Severe Weather Discussion 2009-3-4

Severe Weather Discussion for March 23, 2009.
Valid: 03/23/2009.

Highlights:

– Active severe weather day is expected this afternoon and evening.
Tornadoes, large hail, and damaging winds are all possible. Isolated
severe thunderstorms this afternoon and early evening will pose the
greatest severe weather threat. But mid-evening a squall line is
expected to develop with damaging winds the primary threat.

– Severe thunderstorms are possible on Wednesday with the threat
limited to isolated large hail.

– Severe thunderstorms are possible on Friday for the eastern half of
Oklahoma, another medium-end event may be in store, but need to get
past today first.

– Fire danger is extreme in western Oklahoma where a Red Flag Warning
is posted.

Discussion:

No change to prior forecast reasoning. Models continue to get a
handle on the copious amounts of moisture spreading into the region.
Only Beaumont has a pressure greater than 1016mb and that is only
1016.1mb. With low/mid 60s dewpoints in the Gulf, rapid moisture
return continues across Texas and Oklahoma. 17z surface analysis
shows upper 50s/low 60s across much of Texas with generally mid/upper
50s in Oklahoma. While 60F won't be here in time, we'll be very close
to that number. As such, moisture is not expected to be a major
limiting factor.

Widespread stratus continues across south-central thru northeast
Oklahoma. This is limiting surface heating with temperatures in the
low/mid 60s. However, recent Mesonet solar radiation maps indicate
the cloud cover is thinning, especially on the western edge. Would
expect to see the western half of Oklahoma stratus free by 1pm.
Farther west, an impressive dryline has taken shape just inside the
TX/OK border. Upper 50s are present to the east of this feature with
only a small area of 22F or less in northwest Oklahoma. Mesonet wind
fields show best convergence in the western part of the state and a
line from Watonga to Enid. Temperatures are responding quite nicely
with western ares in the mid/upper 70s and central sections in the
mid/upper 60s. Expect to see quite a bit more warming as the
afternoon sun continues.

17z CAPE map shows 1500 J/Kg in a small wind of northwest Texas into
SW OK. 1000 J/Kg up to I-40 just west of Watonga. This area should
grow during the next few hours as heating occurs to the east once the
stratus deck goes away.

Still think storms will develop between 4-6pm in western Oklahoma,
along the dryline. Only a few storms are expected. A squall line
should develop later in the evening and move across Oklahoma.

I like the Watonga/Weatherford area and this fits nicely with the
thermo fields from 17z. Also, the models (RUC/NAM/GFS) all hit on
something near Clinton developing around 5pm.

Probabilities:

None for this issuance.

Chase Status:

Level 4 – heading out around 3pm for Watogna/Weatherford.

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About Putnam Reiter

Putnam has been storm chasing since 1990 and is a co-founder of Hook-Echo.com. For his day job, Putnam works in emergency management for information technology.
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