Severe Weather Discussion for February 6 – 12, 2012

Posted on February 6, 2012 by Brett LaBare
Severe Weather Discussion for February 6 – 12, 2012.
Issued:  02/05/2012.
Highlights:
-  Showers are possible across the southeast 2/3rds of the state on Tuesday.  Snow is possible in the northwest and the panhandle.  Significant impacts are not expected.
-  Additional rain changes exist for Thursday and Friday, best potential will be in southern Oklahoma.
-  Temperatures will be in the mid 50s Monday, mid 40s Tuesday, low 40s on Wednesday, upper 40s Thursday – Friday, low 50s Saturday and upper 50s Sunday.
Probabilities:
-  Severe Thunderstorms in Oklahoma:  < 5%
-  Storm Chase:  < 5%
-  Winter Precip:  10%
Discussion:
Persistent western U.S. ridge will continue this week in a quasi rex block.  Weakening closed low, which undercut said ridge, will shift slowly eastward as it dampens.  While moisture is limited across the region, there should be enough to generate some light precipitation across the region.  Temperatures will be cold enough in the northwest for snow with rain elsewhere.  Another closed low will undercut the ridge and end up heading through Mexico by mid week.  Another upper system is progged to round the top of the ridge and dive southward and phase with the closed low over Mexico.  Not sure this will be the case, but the GFS seems to think it is a good idea.  ECMWF drops the circulation of the Gulf but either way, precip chances look slim but not zero.  Large closed low over eastern Canada seems to keep a steady supply of cool air moving into the region.  As such, temperatures will be lower this week than the past few but also much closer to normal.
Overall a quiet week is in-store for the region.  Models want to break down the western U.S. ridge later in the forecast period but I’m not convinced of that solution given how long the ridge has been around.
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Severe Weather Discussion for January 30 – February 5, 2012

Posted on January 29, 2012 by Brett LaBare
Severe Weather Discussion for January 30 – February 5, 2012.
Issued:  01/29/2012.
Highlights:
-  Showers and a few thunderstorms are possible in eastern Oklahoma Tuesday afternoon and evening.  And again, Friday, although central Oklahoma may see some showers.  Snow maybe possible next weekend, but low confidence right now.
-  Temperatures will be in the mid 60s on Monday, upper 60s Tuesday, upper 50s Wednesday, mid 50s Thursday, low 50s Friday, near 40F Saturday, and low 40s Sunday.
Probabilities:
-  Severe Thunderstorms in Oklahoma:  5%
-  Storm Chase:  < 5%
-  Winter Precip:  15%
Discussion:
Zonal flow will continue for a few days before the CONUS pattern significantly amplifies.  Models are in decent agreement through 72 hours and then exhibit unusual disparity beyond that point.  Seemingly this is due to the forthcoming pattern change, which the models rarely handle well.  To that end, the forecast beyond Thursday is low confidence and high bust potential.
Shortwave trof will translate across the region on Tuesday in progressive zonal flow.  Said trof will induce a surface low, which is progged to drag at least low 50s dewpoints into the state by Tuesday afternoon.  Degree of heating and moisture return will provide at least a small opportunity for thunderstorms.  In general, showers are the more likely type.  Location of moisture return points to eastern Oklahoma being the primary area for any rain.  After Tuesday a weak Pacific cold front moves through, knocking highs down a little.  18z GFS is more robust with cooling for Wednesday, so this is reflected in my temps.
Upper system then forms near or just west of the region by Friday.  Models differ greatly on the development of this system along with subsequent movement and impacts.  Moisture availability remains high in the Gulf through much of the week, such that any system that can tap it will provide precipitation.  Persistence would argue for all rain no mater what, but climatology argues for snow chances.  So, that is the difficulty of forecasting this week.  The ECMWF’s pattern would seemingly favor snow next Saturday, to which I’ll just have to wait and see.  Special discussions may be required if a snow threat develops, hence the 15% chance.  It is a gamble, but we’ll see.
Went above MOS Monday/Tuesday, then with Wednesday/Thursday and below the remainder of the week.  As noted above, potential for colder temperatures Saturday and Sunday but I think the going numbers are cold enough for now.
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Severe Weather Discussion for January 23 – 29, 2012

Posted on January 23, 2012 by Brett LaBare
Severe Weather Discussion for January 23 – 29, 2012.
Issued:  01/22/2012.
Highlights:
-  Showers are possible Tuesday into Wednesday, best chance is southern Oklahoma.
-  Temperatures will be in the upper 50s Monday, mid 50s Tuesday, upper 40s Wednesday, mid 50s Thursday, low 60s Friday, low 50s Saturday, and mid 50s Sunday.
Probabilities:
-  Severe Thunderstorms in Oklahoma:  < 5%
-  Storm Chase:  < 5%
-  Winter Precip:  < 5%
Discussion:
Powerful shortwave trof passing over Oklahoma this evening will continue moving east and then northeast the next few days.  Significant severe weather event underway across Arkansas and points east this evening.  NWS Little Rock issuing tornado warnings referencing large damaging tornadoes.  A Pacific cold front has moved into Oklahoma this evening and is progressing rapidly southeast as the surface low translates northeast away from the state.  Very warm temperatures today will become mild mid-winter temperatures on Monday in wake of the cold front.
Models consistent on develop a southwest U.S. closed low in the split flow across the U.S.  Said low show lumber slowly across Texas through Thursday and eventually get absorbed into the mean flow as a longwave trof develops across the northeast U.S.  Presence of 70F dewpoints in the Gulf, even in the wake of the current system, should provide plentiful moisture for the expected closed low Tuesday/Wednesday.  Model QPF values appear high for Oklahoma, especially the NAM.  The GFS is more reasonable and likely captures the expected areal extent of the rainfall.  Closed low leaves the region late Thursday with little in the way of impacts beyond then.  A cold front is expected to move through the region as the northeast system takes shape.  This will cool things off for the weekend.  For now, haven’t gotten aggressive on temperatures since winter 2011/12 has been mild so far.  At this point, GFS shows no Arctic intrusions through the remainder of January.
GFS temps look good and ECMWF agrees an the basic points of the forecast.
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Severe Weather Discussion for December 26, 2011 – January 1, 2012

Posted on December 27, 2011 by Brett LaBare
Severe Weather Discussion for December 26, 2011 – January 1, 2012.
Issued:  12/26/2011.
Highlights:
-  Temperatures will be in the upper 40s Monday, mid 50s Tuesday, upper 50s Wednesday, near 60F Thursday, and low 60s Friday-Saturday, and mid 50s Sunday.
-  Happy New Year!
Probabilities:
-  Severe Thunderstorms in Oklahoma:  < 5%
-  Storm Chase:  < 5%
-  Winter Precip:  < 5%
Discussion:
Beautiful early winter week ahead for Oklahoma with temperatures a little above normal area wide.  Upper low that has been wobbling in west Texas the past few days is slowly lifting eastward and will be out of the region by late Tuesday.  After that the flow goes zonal with little in the way of impacts in Oklahoma.  Models show a few wind shifts nearby, but nothing significant.  ECMWF does show an eastern U.S. longwave trof developing just beyond this forecast period.  This would seemingly cool things off significantly if cold air builds in Canada.  At this time, precipitation looks nil across the region so all POPs zero through Sunday. GFS is a few days later regarding the eastern U.S. trof, so we’ll see.  Luckily I don’t have to make a call at this point.  However, Sunday could see a cool-off.
Went with GFS MOS through Saturday and then below on Sunday which seems in-keeping with forecasts to the northeast.
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Severe Weather Discussion for December 19 – 25, 2011

Posted on December 18, 2011 by Brett LaBare
Severe Weather Discussion for December 19 – 25, 2011.
Issued:  12/18/2011.
*Significant Winter Weather Event for the Panhandle*
-  Blizzard Watch is posted for the Oklahoma panhandle with an upgrade to a Blizzard Warning likely for Monday into Tuesday.  Snowfall totals of 10-12 inches are likely with isolated ares up to 16 inches.
-  Winter Storm Watch is posted for far northwest Oklahoma with 3-6 inches of snow likely Monday into Tuesday.
-  Widespread rain is likely across much of Oklahoma Monday into Tuesday with some areas getting 1-2 inches.
-  A dusting of snow to one inch is possible from Oklahoma City north and west by Tuesday evening.
-  Temperatures will be near 50F Monday, falling on Tuesday into the mid-30s by late afternoon, mid 40s Wednesday – Thursday, near 40F Friday, mid 40s Saturday, and upper 40s Sunday.
-  Winter officially starts on Thursday, but the folks in the panhandle probably don’t care.
-  Merry Christmas to all!
Probabilities:
-  Severe Thunderstorms in Oklahoma:  < 5%
-  Storm Chase:  < 5%
-  Winter Precip:  50%
Discussion:
Wouldn’t be Christmas week in Oklahoma without a blizzard!  Models are in good agreement regarding the evolution of a closed southern stream shortwave low currently south of San Diego.  Said system is expected to drift eastward the next 12-18 hours and then start moving slowly northeast.  Models prog this system to move over the Texas panhandle and western Oklahoma into Kansas.  The general location of the heaviest snow track is well handled by the models.  As such, much of the Texas panhandle, Oklahoma panhandle, and southwest Kansas will get hit with at least 12 inches of snow.  Isolated amounts to 16 inches are also possible.  Elsewhere, a cold rain is expected.  Plenty of moisture is available, so model rainfall totals of 1-2 inches appear reasonable.  This should go a long ways against the current drought.  It will likely remove the D4 from Oklahoma as the panhandle has the only remaining area of D4.  Kept the winter precip at 50% due to the areal coverage of the event, even though it is high-end.
After this system passes, the pattern quiets down some.  There are two other systems progged to move over the region, but none are likely to cause any issues due to lack of moisture.  They will help keep the region cool much of the week.
NAM MOS was used through Wednesday and then undercut the GFS some through the rest of the week.
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Severe Weather Discussion for December 12 – 18, 2011

Posted on December 12, 2011 by Brett LaBare
Severe Weather Discussion for December 12 – 18, 2011.
Issued:  12/11/2011.
Highlights:
-  Severe thunderstorms are possible on Wednesday, showers are possible on Tuesday.
-  Slight chance of rain/freezing rain on Saturday/Sunday.  Best potential for rain is southeast Oklahoma.
-  Temperatures will be in the low 50s Monday, upper 50s Tuesday, low 60s Wednesday, mid 50s Thursday, mid 40s Friday, low 40s Saturday, and upper 30s Sunday.
Probabilities:
-  Severe Thunderstorms in Oklahoma:  20%
-  Storm Chase:  < 5%
-  Winter Precip:  15%
Discussion:
Complex forecast this week with two at least low-end events and potential for a near medium-end event both times.  Model issues make forecasting quite difficult, even for the Wednesday event and certainly for next weekend.
Split flow will continue this week with southern stream systems diving south over California and then ejecting eastward across the region.  Two such systems are expected with the first Wednesday and the next during the weekend.  The first system has been consistently progged by all models to increase moisture across the state with low 60s likely by Wednesday afternoon.  The WAA pattern should result in widespread clouds across the state with heating seemingly minimal.  However, given the trend for 2011, severe weather prevails.  I’m not going to ignore the setup, although the primary threat will be large hail.  Medium-end events can occur in December, I believe it was December 12, 1991, which was a moderate risk.  Although nothing came of it due to high shear and very low thermo but SPC still did a tornado watch.  Upper system passes with little change in airmass.  Temperatures will be a little cooler absence WAA pattern.
Next upper system approaches the region next weekend and the models are in somewhat better agreement.  ECMWF and GFS keep swapping viewpoints with each other.  At this time the GFS’s progression is more typical of what we’ve seen this fall and what is expected next weekend.  The issue becomes the surface pattern, which none of the models seem to handle well.  The 500mb northern jet isn’t well defined and a significant cold air dump doesn’t seem likely.  However, temperatures will be below freezing during precipitation times next Friday-Sunday, such that freezing rain is possible.  Model soundings show the moisture in the lower few thousand feet of the atmosphere with little chance for snow.  At this time do not see a significant winter weather event, but a little of the freezing rain goes a long ways!  This is true for travelers, with minimal sun angle and surface heating.
Both setup will be monitored but at this juncture, special discussions are not anticipated.
Upper system clears the region on Sunday with quiet conditions for a few days.  GFS shows another southern stream system approaching the region around Christmas eve and no I’m not going there.
Followed the NAM somewhat on temperatures.  Wednesday will either be in the low 60s or near record breaking low 70s.  I’m sticking with the low 60s for now.  Beyond Wednesday went with general pattern, which agrees best with OUN and ECMWF.  GFS seems off and a little high in general.
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Severe Weather Discussion for December 5 – 11, 2011

Posted on December 6, 2011 by Brett LaBare
Severe Weather Discussion for December 5 – 11, 2011.
Issued:  12/04/2011.
Highlights:
-  Showers are likely in the southeast part of Oklahoma tonight into Monday.
-  A dusting of snow is possible in western Oklahoma on Monday with flurries elsewhere.  The panhandle stands the best chance of snow with 1-2 inches likely.
-  Temperatures will be in the low 40s Monday, mid 30s Tuesday, low 40s Wednesday, mid 40s Thursday-Saturday, and upper 40s Sunday.
Probabilities:
-  Severe Thunderstorms in Oklahoma:  < 5%
-  Storm Chase:  < 5%
-  Winter Precip:  10%
Discussion:
The great snow storm of 2011 take three appears to be an illusion as all models have converged on higher QPF remaining well south of Oklahoma.   The displacement will also remove the QPF from the colder air, thereby not supporting snow in Oklahoma City or Tulsa.  Snow is likely in the Oklahoma panhandle where a Winter Weather Advisory is posted.
Current system prompting lots of showering activity in Texas and northeast as it shears eastward across the state.  This system will have little influence beyond today as it enters confluent flow and dampens.  Next southern stream shortwave trof will linger over New Mexico, which is progged to bring snow to the Oklahoma panhandle Monday into the evening hours.  This may also bring some snow to western Oklahoma, where a dusting is possible.  Farther east, flurries are about it.  The system will race northeast as the large closed low over northern Canada strengthens and a shortwave trof dives south over Wisconsin/Minnesota by midweek.  The main influence on Oklahoma will be a cold air pump that will continue much of the week.  This will keep temperatures below normal all week, with at least a few days in the 30s.  It will also usher in the coldest morning of the season when temperatures will likely reach the upper teens.  Mid-level pattern starts to flatten out by late week with a warming trend expected across Oklahoma.  No appreciable precipitation is expected after Tuesday across the state.  This would seemingly break the weekly rainfall events we’ve seen for the past month.  On the other hand, these have greatly reduced drought conditions across the eastern half of the state.  GFS does show a shortwave trof moving across Kansas next Sunday.  It does not develop QPF with this system and moisture appears to be lacking at this time.  However, should the system amplify or slow down, moisture may be available when it traverses near the region.  Either way, it is beyond this forecast period.
Generally went below MOS forecasts for the week, very much inline with NWS Norman.  Models are in decent agreement all week on the 500mb pattern.
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Severe Weather Discussion for November 21 – 27, 2011

Posted on November 21, 2011 by Brett LaBare
Severe Weather Discussion for November 21 – 27, 2011.
Issued:  11/20/2011.
Highlights;
-  Severe thunderstorms are possible in southeast Oklahoma on Monday.  Primary threats are large hail and damaging winds, but a few tornadoes seems probable. Widespread showers and thunderstorms are likely elsewhere.
-  Thunderstorms, maybe a severe one or two, are possible Friday across the eastern 1/3rd of Oklahoma.  Primary threat is large hail.
-  Temperatures will be in the mid 40s on Monday, near 60F Tuesday, mid 60s Wednesday, upper  60s Thursday – Friday, mid 50s Saturday, and near 60F Sunday.
- Happy Thanksgiving!
Probabilities:
-  Severe Thunderstorms in Oklahoma:  15%
-  Storm Chase:  < 5%
-  Winter Precip:  5%
Discussion:
Southern stream shortwave trof will move into the region late Monday and move across during the afternoon hours.  A synoptic cold front is currently held up over north Texas this evening with mid/upper 60s dewpoints to its south.  To the north, temperatures are commonly in the 40s.  As the upper system approaches, the boundary is expected to drift northward, allowing for warm/moist air to shift northward into southeast Oklahoma.  Models disagree as to how far north the warm front will move, but for now I am siding with the farther north NAM.  Where ever the front ends up, severe thunderstorms are likely near and to the south of this feature.  Favorable shear will pose a tornado threat.  Isentropic lift will increase in earnest Monday afternoon, allowing for numerous showers and thunderstorms across much of Oklahoma.  Beneficial rainfall looks on-tap for eastern Oklahoma where a flash flood watch is currently posted.  Given that some of these areas are in a D0-D1 drought, some parts of Oklahoma maybe cleared of drought conditions.  After the system passes early Tuesday, a cool day is expected with a warming trend through Friday.  Models are in good agreement with this pattern and Thanksgiving is likely to be very pleasant across Oklahoma and Texas.
Next system moves towards the region late Thursday into Friday.  18z GFS took a radical departure from prior runs and the 12z ECMWF.  It cannot be ignored given that the prog valid 126hrs is similar to the current incoming system.  There are differences in the overall forecast from this change but nothing significant.  The main change was to move rain changes back west and add thunder for eastern Oklahoma.  Models indicate decent moisture return, dewpoints in the 50s, ahead of the dryline and eventually cold front.  Currently there seems decent potential for eastern Oklahoma/Texas to pick up another 1/2 to 1 inch of rainfall.    Systems moves on by for a cool Saturday and Sunday across Oklahoma.
Followed NAM for temperatures through Tuesday and then the GFS in-general through Sunday.  12z NAM has mid 40s tomorrow and given expected isentropic lift/clouds, see no reason to disagree.  OUN followed the same.  SPC outlook for tomorrow also looks good.
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Severe Weather Discussion for November 14 – 20, 2011

Posted on November 13, 2011 by Brett LaBare
Severe Weather Discussion for November 14 – 20, 2011.
Issued:  11/13/2011.
Highlights:
-  Showers and a few thunderstorms are possible on Monday, primarily in southeast Oklahoma.
-  Severe thunderstorms are possible in western Oklahoma on Sunday.
-  Temperatures will be in the low 70s Monday, near 70F Tuesday, mid 50s Wednesday, near 60F Thursday, mid 60s Friday, near 70F Saturday, low 70s Sunday.
Probabilities:
-  Severe Thunderstorms in Oklahoma:  25%
-  Storm Chase:  10%
-  Winter Precip;  < 5%
Discussion:
After a very active start last week, this week will be much more quiet.  Northern stream medium-wavelength trof will translate into the central U.S. on Monday as it picks up a closed southern stream low in Mexico.  The latter system will move across Texas on Monday, allowing for much needed rain.  For the most part, Oklahoma will miss out on this system, but southeast sections are likely to see some rain from it.
A cold front will follow the northern stream system late Tuesday, ending several days of warm temperatures across the state.  Wednesday and Thursday will be cool with a warm-up into the weekend.  ECMWF/GFS are in decent agreement regarding the development and progression of a southwest U.S. medium wavelength trof by next week.  The main question will be how fast this system moves east towards Oklahoma.  GFS was too progressive with the system last week and could be again this week.  Although the GFS’s solution is certainly favorable for severe weather.  The last frame of the ECMWF seemed to indicate the upper system would continue to dig southward will the GFS had already turned it east.  Either way, moisture return and upper flow will be sufficient for severe thunderstorms whether it be Sunday or Monday.  Question would be heating as that isn’t a given this time of year.  I went ahead and put in severe for western Oklahoma on Sunday, so we’ll see how it all develops.  GFS has a dryline on the TX/OK border at 6pm Sunday with at least low 60s dewpoints across the state.  Wind speed and shear are both more than adequate for severe thunderstorms.  Again, this is one model and seven days out, so the story may indeed change.
MOS numbers look acceptable this week with minimal tweaking.
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Severe Weather Discussion for November 7 – 13, 2011.

Posted on November 6, 2011 by Brett LaBare
Severe Weather Discussion for November 7 – 13, 2011.
Issued:  11/06/2011.
Highlights:
-  Severe thunderstorms are likely Monday afternoon and evening mainly in western and parts of central Oklahoma.  Primary threats are destructive wind, large hail, and a few tornadoes.  SPC indicates the potential for a strong tornado.  Given the current Day 2 outlook, a moderate risk may be in the offering tomorrow.
-  Severe thunderstorms are possible Tuesday morning and afternoon across central and eastern Oklahoma.  Destructive wind and large hail are the primary threats, with continued potential for a few tornadoes.
-  Slight chance of showers on Saturday, better chance of widespread showers and some thunderstorms on Sunday.
-  Temperatures will be near 70F Monday – Tuesday, upper 50s Wednesday, low 60s Thursday, mid 60s Friday, upper 60s Saturday, and mid 60s Sunday.
Probabilities:
-  Severe Thunderstorms in Oklahoma:  50%
-  Storm Chase:  < 5%
-  Winter Precip:  < 5%
Discussion:
Interesting setup for Monday as a late season severe weather episode appears to be on-tap.  Models are in good agreement on the overall setup of a shortwave trof ejecting eastward across the state late Monday into Tuesday.  Decent moisture, characterized by surface dewpoints in the low 60s will move northward through Oklahoma during the overnight hours into Monday.  The big question for severe thunderstorms on Monday continues to be the potential of widespread rainfall.  18z NAM has continued the trend of reducing morning rainfall and increasing instability parameters Monday afternoon.  As is always the case, it is a gamble as to which scenario will verify.  For now, the potential is in-place for severe thunderstorms on Monday with concerns of an active severe weather day, especially given time of year.  SPC has issued a slight risk with 30% and 10% hatched areas for much of western and parts of central Oklahoma.  This is reasonable and see no reason to deviate.  Setup has some similarities to February 10, 2009, so will be interesting to see how this plays out.  One big difference is the dryline will be near I-27 Monday afternoon.  Either way, thunderstorm development is likely Monday afternoon and storms will progress rapidly eastward during the late afternoon and evening hours.  Very strong jet streaks aloft will create potential for destructive winds while speed/directional shear will create an environment favorable for large hail.  SPC is also targeting a strong tornado threat, mainly in the area of SW OK/NW TX given expected better moisture and heating.  18z NAM does develop some QPF near OKC Monday afternoon, but not sure the reason for it.  If storms develop overnight, then outflow boundaries will be a player on Monday.
Beyond Monday, the upper system will be moving across Oklahoma on Tuesday with a dryline moving east of I-35 by early afternoon.  NAM/GFS are at odds but the NAM has shifted eastward, closer to the GFS position of a dryline near OK/AR border at 00z (6pm).  As such, parts of eastern Oklahoma will be in a severe threat on Tuesday, but the significance is muddied due to expected convection on Monday.
Upper trough then exits the area with a cold front moving across Oklahoma late Tuesday.  Wednesday-Friday will be mild and dry, with a warming trend Thursday and Friday.  GFS and ECMWF both forecast another shortwave trof to dig into the mean longwave trof position over the western U.S. by Saturday.  A weak shortwave trof will eject eastward on Saturday and may influence Oklahoma late in the day.  Models have no QPF for this time period, but I added POPs anyway given warm advection regime that is likely to setup as mid 50s dewpoints move through north Texas.
A stronger shortwave trof will eject eastward on Sunday, which should lead to widespread showers and thunderstorms across the state.  ECMWF is a little slower but the overall trend is the same.  There is the potential for most of the rainfall to occur just beyond this forecast period.  A severe weather threat may develop given temperatures in the upper 60s and dewpoints in the low 60s.  Indeed the GFS has 1000 J/Kg CAPE values across western Oklahoma.  For now, I’m going to leave the severe chances low.  GFS winds are very strong with 200MB 120-140kts and 500mb 70-80kts.  We’ll see what comes of it, but next Sunday is likely to be windy at the very least.
Temperatures, oh boy these can be fun.  I went with near 70F Monday and Tuesday given expected location of surface features and that the cold front on Tuesday may be late in the afternoon.  As such, a warmup behind the dryline appears likely.  Wednesday will be cool with a warming trend into Saturday.  Sunday is rough since I’m thinking showers will be widespread and keep temperatures down, I went with mid 60s. Severe probability is set to moderate risk for Monday and Tuesday.  If this was October or April/May, we’d be chasing tomorrow but time of year doesn’t support it for us.
I must say, it is quite nice to have a western U.S. longwave trof, been too long!
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Severe Weather Discussion for October 17 – 23, 2011

Posted on October 17, 2011 by Brett LaBare
Severe Weather Discussion for October 17 – 23, 2011.
Issued:  10/16/2011.
Highlights:
-  One or two severe thunderstorms are possible tomorrow afternoon, primarily in far south-central and southeast Oklahoma.  Otherwise, thunderstorms are possible across the southeast quarter of the state.  Slight chance of showers on Sunday.
-  Temperatures will be in the low 80s Monday, mid 60s Tuesday, low 60s Wednesday, upper 60s Thursday, low 70s Friday, upper 70s Saturday and Sunday.
-  NHC is watching a system near the Yucatan, giving a 50% chance of development.
Probabilities:
-  Severe thunderstorms in Oklahoma:  5%
-  Storm Chase:  < 5%
-  Tropical Development:  10%
Discussion:
Models are in good agreement through the period on the general weather pattern.  A southern stream shortwave trof will move southeast across the state and help form a large eastern U.S. longwave trof.  Initial closed low over the eastern Canada will open and move east as the longwave trof matures and closes off by late Wednesday.  As the eastern Canada closed low spins, a decent chunk of cool air will head southeast into the region.  Frontal passage is expected Monday afternoon across the state.  Some low-level moisture, around 60F dewpoints, will move into the state.  Warm temperatures and a strong cap will battle each other for storm initiation.  Given the expected warm temperatures and CAPE values around 750 J/Kg, one or two severe thunderstorms cannot be ruled out.
Cold front will then move southward thru Texas by Tuesday afternoon, ushering in a cool day across Oklahoma.  A shortwave trof will dive southward on the backside of the long wave trof late Tuesday resulting in a reinforcing surge of cool air.  As such, Wednesday temperatures will likely be a little cooler than Tuesday.  After Wednesday, a warming trend will start, with temperatures finishing the forecast period above average over the weekend.  All POPs zero after frontal passage late Monday until Sunday.  GFS trof for Sunday may be a one run wonder, but can’t hurt to put in token POPs for Sunday.  If POPs do verify, temperature may be a little high.  All in all, a pleasant fall week looks like a good bet.
Went with NAM tomorrow on high temperature, although not quite as warm.  GFS appears too cool.  Beyond Monday, GFS numbers look find and didn’t make many changes.
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Severe Weather Discussion for September 12 – 18, 2011

Posted on September 11, 2011 by Brett LaBare

Severe Weather Discussion for September 12 – 18, 2011.
Issued:  09/11/2011.

Highlights:

-  Showers and thunderstorms are possible Wednesday through Friday.  Slight chance of showers Saturday and Sunday.

-  Temperatures will be in the mid-90s Monday-Tuesday, mid-80s Wednesday, mid-70s Thursday, upper 70s Friday, and low 80s Saturday-Sunday.

Probabilities:

-  Severe Thunderstorms in Oklahoma:  5%
-  Storm Chase:  < 5%
-  Tropical Development:  15%

Discussion:

Models are in good agreement with the overall pattern this week, oddly so given the somewhat weak influences in the area.  The stories this week are warmth, a cool front, then a cold front, and then maybe just maybe some rain.

Upper ridge will remain over the region through Tuesday resulting in a spike in temperatures both days.  This has a northern stream shortwave trof curves out a larger trof in the northeast.  The initial shortwave trof will push a cool front into the state, which should stall in southern sections.  By Thursday a closed low translates into the mean longwave position resulting in a stronger cold front into the region.  The latter of these boundaries will be in-place as a weak shortwave trof moves eastward towards the region.  This should provide a favorable upslope pattern with southerly winds in Texas.  The GFS is very excited about precipitation on Thursday showing 1-2 inches across a large part of Oklahoma.  No doubt this would be welcomed rainfall and far more than received over the past few months.  However, impacts from Nate do worry me as it has modified the southern Gulf and some trajectories.  While I do think rain is likely Thursday, I’m hopeful the GFS is correct.  It hasn’t been all that consistent with amounts, so we’ll see.  Southwest trof weakens and shortwave trof moves across the northern U.S. which may result in a weak cool front late in the week.  For now, not gonna worry about that one.

We are still in peak tropical season, although Maria seems to be the last thing spinning for now.  We’ll see if another system develops this week.  Not sure what we’ll get after Nate sitting in the Gulf for several days.

MOS was pretty good on temperatures and did not deviate all that much.  Very dry ground may still encourage odd temperature swings, but don’t see much of that this week.

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Severe Weather Discussion for August 29 – September 4, 2011

Posted on August 29, 2011 by Brett LaBare

Severe Weather Discussion for August 29 – September 4, 2011.
Issued:  08/28/2011.

Highlights:

-  Showers and thunderstorms are possible Monday-Thursday, with a decent chance Friday-Sunday.

-  Temperatures will be near 104F Monday, 102F Tuesday-Thursday, and mid 90s Friday-Saturday.

Probabilities:

-  Severe Thunderstorms in Oklahoma:  10%
-  Storm Chase:  < 5%
-  Tropical Development:  30%

Discussion:

Now that Irene is making a graceful exit from the northeast U.S., life as we know it can get back to normal.  Maybe even a decent TV show or something, although I’ll be avoiding Cantore Stories for now.

Models are similar in continuing the persistence and rather irritating ridge to our west.  OKC reached 108F today, blowing away the prior high of 103F and giving OKC day 56 of 100F temperature.  Appears that several more are on the way before a “cool” down.  However, despite typical weather this time of year, the cool down may not be driving by the mid-latitudes but a tropical system moving northward into Texas and potentially southern Oklahoma.  The increase in moisture associated with this system, along with lift should be enough for showers and thunderstorms across the region later in the week.  The system is due in around Thursday/Friday.  This should also keep temperatures from reaching 100F in OKC.  The ridge also looks to weaken, so lower heights may also help.  Between now and then, status quo seems the rule.  No reason to get fancy with temperatures as near 100F looks likely through Thursday, with the ridge placed to the west of OK and heights 591dm and above.  Storms are ongoing in western Oklahoma and as has been the case much of the summer, can’t rule out development through the week.  However, the best chance will be late this week as the tropical system moves into the region.

Went with NAM temps through Wednesday and GFS through Friday.  I kept temps up a little this weekend given recent trends of a cool bias.

Tropical development remains up as there is another system just west of Africa.

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Severe Weather Discussion for July 18 – 24, 2011

Posted on July 17, 2011 by Brett LaBare

Severe Weather Discussion for July 18 – 24, 2011.
Issued:  07/17/2011.

Highlights:

-  A few thunderstorms are possible most any day this week, although better chances appear Friday-Sunday.  Severe chances are low, but not zero.

-  Temperatures will be in the 102-105F range Monday-Sunday.

Probabilities:

-  Severe Thunderstorms in Oklahoma:  5%
-  Storm Chase:  < 5%
-  Tropical Development:  15%

Discussion:

Little change to the going forecast this week.  Despite 500mb heights of 596dm, temperatures in OKC have struggled to reach 100F.  Upper ridge is forecast to weaken some and shift northeast later in the week as a medium wavelength trof develops to the west.  This trof will do little for the region with the main influence southerly flow on the west side of the ridge.  A few easterly waves look to move near the region with the best potential later in the week for rainfall.  However, even that is low but POPs are still warranted.

Climatological temperature max occurs today through August 13th, so the heat will remain and this is also a given per very dry ground.  Latest drought monitor shows much of western OK in a D4 and all of Oklahoma in a drought, the majority D1 – D4.  OKC has reached or exceeded 100F 27 times this year, now 23 away from the record set in 1980.  The current consecutive days is 5, with the record 22.  GFS still hasn’t gotten a clue and is ignored.  The ensembles seem to be catching on but the operational GFS is still out to lunch.  NAM/ECMWF have performed well and will stay with them on temperatures.  I didn’t get too fancy this week, as I don’t see much of a spread during the week.  Potential for thunderstorms Saturday-Sunday may be enough to shave a few degrees off like last Tuesday/Wednesday.

Tropics got active as we have TS Bret.  I went with 15% as it will be around this week but is not a threat to the U.S. at this point.

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Joplin Tornado – Before and After

Posted on July 12, 2011 by Brett LaBare

Quite an amazing video.

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