Severe weather discussion – April 7-13

Severe Weather Discussion for April 7 – 13, 2014.
Issued:  04/06/2014.
 
Highlights:
 
–  Showers are likely on Monday across Oklahoma, overall rainfall amounts will be low.
 
–  A few thunderstorms are possible on Saturday across western Oklahoma.  A severe thunderstorm is possible.
 
–  Severe thunderstorms are possible on Sunday across central/eastern Oklahoma.
 
–  Temperatures will be in the low 60s Monday-Tuesday, mid 70s Wednesday, mid 80s Thursday, low 80s Friday-Saturday, and upper 70s Sunday.
 
Probabilities:
 
–  Severe Thunderstorms:  25%
–  Storm Chase:  15%
 
Discussion:
 
Current upper system will impact the region through Monday as multiple waves move through.  By Tuesday, the upper system will be gone and mid-level ridging is expected.  Dewpoints are low across the region due to the system on Thursday.  As such, precipitation amounts will be on the low side.  However, given the ongoing drought, we’ll take what we can get.
 
Mid-level ridging will dominate the region through Friday.  Beyond Friday, models agree that a southern stream closed low will move onshore in the southwest US early Saturday.  12z EC forecasts this system to open up and eject east-northeast into the region on Sunday.  The GFS is a little slower and much farther south.  It also keeps the low closed longer than the EC.  Both models are seemingly correct, however this week I’ll side with the EC.  This has been the ongoing pattern this season.  Current upper system will clear tropical moisture from the Gulf and as such, only modified moisture return is expected on Saturday.  Models do show more robust moisture return on Sunday but not what we had last Thursday.  Despite this, a few thunderstorms are possible on Saturday across western OK near developing dryline.  Residual shortwave ridging will likely keep storms limited.  Models do indicate a thunderstorms or two along the dryline Saturday afternoon.  Time of year does favor a few severe thunderstorms. 
 
Upper system approaches Oklahoma on Sunday and is shown by the EC to shift east of the state by late Sunday.  This isn’t exactly favorable for sever thunderstorms, but a timing change of only a few hours could increase severe weather chances.  EC winds are favorable for organized severe thunderstorms and right now the most likely area is eastern OK.  I added central into the discussion since a timing change is possible.  If the GFS is correct, a day similar to today is likely with cloudy, cool and rainy conditions. 
 
First guess at number is close to going NWS and models, changed Monday.  I left Sunday in the upper 70s, since seemingly it is possible should the cold front slow down.  Either way, beyond Sunday the incoming cold front will knock temperatures back down below normal for a few days.  Models indicate some freezing temperatures in Oklahoma in 7-9 days.  In other news, 242 days without a tornado in Oklahoma and Monday makes eight months. Still 50 or so days from the record, but since 1950 only 10-11 years with no tornadoes Jan-Mar.  The latest tornado for a given year is April 26th.  I don’t see us making that date, but we’ll see.
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