Severe Weather Discussion for February 4 – 10, 2013

Severe Weather Discussion for February 4 – 10, 2013.
Issued:  02/03/2013.
Highlights:
–  Showers are expected across parts of the eastern half of Oklahoma Monday morning.  Amounts will be AOB 0.25 inches.
–  Additional showers and maybe a thunderstorm are expected Wednesday afternoon into Thursday across much of Oklahoma.
–  Severe thunderstorms are possible Saturday and Sunday, but more likely another run of showers and thunderstorms.
–  Temperatures will be in the upper 50s Monday, low 60s Tuesday-Wednesday, upper 50s Thursday – Friday, and mid 60s Saturday – Sunday.
Probabilities:
–  Severe Thunderstorms in Oklahoma:  20%
Discussion:
Models pointing to more rain chances across the state this week as northwest flow gives way to a southwest U.S. closed low.  Some differences among the medium range models exist for later in the week.
Before this time, a wave moving southeast in mean northwest flow will produce some showers across eastern Oklahoma Monday morning.  This activity will clear out after sunrise with dry conditions through Wednesday afternoon.  Late Wednesday a weak southern stream shortwave trof will move into the region and produce another round of showers and thunderstorms.  18z NAM shows some elevated CAPE so a boomer or two seems like a good bet.  This activity continues into Thursday, as a cold front moves through the state, after which time the system translate east of the region. There isn’t much cold air associated with the front, so temperatures won’t respond too much.
Closed low settles into the SW U.S. by Friday and slowly moves towards the region.  Recent models runs have slowed this system and the 18z GFS looks a little more realistic.  It also seems to fit with the 12z EC although the latter is more open and a few hour more progressive.  Either way, decent rain chances should accompany this system with another chance for severe thunderstorms.  GFS shows CAPE values @1000 J/kg but rain cooled air is also a concern.  So, the significance of the event is rather iffy right now and GFS is also much lower on moisture than last Tuesday.  This is due in-part to Thursday’s cold front, which pushes moisture to the Gulf.  Time of year would argue for limited moisture return, so we’ll see just how much can get back up here.  Either way, enough confidence exists for a D6-D7 forecast to put in severe chances.  SPC has noted the potential but don’t think they’re going to risk the state right now since a moderate doesn’t seem likely.  Now, if the system slows even more, a moderate could be in the offering as it ejects on Sunday.  Another consideration is the difference between the EC and GFS re open wave and closed low.
Temperatures are going to be tricky this week and plenty of potential to get burned.  Didn’t get too fancy, either way temperatures will remain above normal.
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