Weekly Severe Weather Discussion

Severe Weather Discussion for February 5 – 11, 2007.
Valid: 02/05/2007.

Highlights:

– Above normal temperatures today and tomorrow. Below normal temperatures Wednesday – Sunday.

– Very slight chance of freezing drizzle Wednesday night and snow Saturday.

Probabilities:

– Severe Thunderstorms in Oklahoma: < 5%
– Storm Chase: < 5%
– Winter Precip: 15%

Discussion:

Days until storm season: 38

Well, I should apologize to the over-sized rat, for calling him an over-sized rat and taunting his forecasting skills. Today was an awesome day and tomorrow should be even nicer. These are rare days in Oklahoma for February, but I'll take them.

12z GFS/ECMWF are in decent agreement that split flow will continue this week with de-amplification of the atmosphere across the lower 48. Farther northwest the very strong northern stream ridge will continue to produce cross-polar flow, reloading western/central Canada with cold air. This pattern will remain in place this week. Models are odds on how long this pattern will last, but prior experience dictates the strong blocking ridge should remain in-place through this week. We may see a weakening of this pattern mid/late next week.

What this means for my region is more moderate temperatures as the lower 48 flow will not be as amplified and the bulk of the cold air going east, as it did this weekend. That being what screwed me on the latter part of my forecast from last week.

Now, this doesn't mean there isn't some fun to be had around here. Active southern jet stream will continue to produce weak and progressive shortwave trofs. These may combine at any point with a Canadian cold front to produce winter precip. Current thinking from the NWS (and I see no reason to disagree) is Wednesday night into Thursday and again on Saturday. GFS dewpoint plot shows 50F dewpoints just south of the Red River Wednesday night. This would help lead to freezing drizzle, per the forecast; which should be about it given weak dynamic lift. Another such system will move into the region late Saturday and may actually produce some snow. Over all, coverage and intensity isn't even to go over 15%, although a little freezing drizzle/rain goes a long way as I experienced last Wednesday on my way home. Current normal is 51F and temperatures will be in the 30s and low 40s after Tuesday.

12z GFS indicates a stronger southern stream shortwave trof moving into the region around Monday. Dewpoints should be in the 55-60F range given that the Gulf has been worked over the past few weeks and some of the moisture may have modified Canadian air with it. GFS has a narrow area of 500-750 J/Kg CAPE along the dryline Monday afternoon. Deep convection would likely be very scattered given the rather forced nature of the event. However, severe thunderstorms would certainly be possible north Texas into south Oklahoma given co-location of PVA, UVV's, and jet streaks to assist in lift across a large area. Most likely setup will yield widespread convection developing during the late morning hours on Monday as omega fields indicate lift in this region. Low-end severe thunderstorms are possible as forced convection develops with the approach of the upper system. It is certainly a sign that severe weather season is approaching.


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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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