Friday, March 19, 2010

Update of Recent Weather conditions in USA southern plains

Akshay Deoras

Concerning- Heavy snowfall with Winter storm condition in Oklahoma and weak storms in LA,MS

A powerful system is expected to enter Oklahoma shortly causing heavy rains which will convert rain to snow at some places due to approaching cold front.The 850mb forecast models of 00z RUN is showing an intensifying low level jet of 40kt over western Oklahoma.
The overhead low means a winter storm condition with high wind crossing 40miles/hour.
The accumulated rain/snow models is showing significant snowfall of as high as 10" + in still water Oklahoma and 3-5" for Altus,OK. Blowing snow is expected as the winds achieve 33mph in NWSTRN OK,32mph in OKC. NWS HAS ISSUED WINTER STORM WARNING AND WATCHES FOR OKLAHOMA. The temperatures are going to be negative in this region infront of the cfront.
People must undertake all the safety measures.
Meanwhile as Oklahoma will continue with Winter storm, for the 09z,an approaching storm will lash central parts of Texas. These upper level low will fire LLJ with 30kt gusts over parts of Central TX to Upper parts of TX.Helicity index for the lower level shows 200m2,s2 values which will be helpful in rotating the storm. The updrafts will be pretty intense in these regions as the CAPE rises to more than 1000J/kg.
The SKEW-T map shows a OC at the favoured lower levels 650mb which will be helpful in creating the hails. Storms will fire here after the half part of morning. Damaging wind gusts are expected here.The threat for tornadoes however remains 2% with the threat of Hails about 5%. THe EHI<0-1km> is showing high energetic conditions of 2.0 which might create supercells.
The same day,threat for Louisiana and MS valley for thunderstorms decreases as uptil 21z, no lows will move EWDS To the MS Valley. The storms will line up at the pre-frontal activity zone which will slow the condition as analyzed by the NAM.
I bet Texas has a good scope than MS on saturday. At 27z,cyclogenesis at the lower level will strengthen the storm and push the LLJ EWDS.
After 36z, storms will fire in different zone of the southern MS,AL.
The instability remains too less there as the cold front approaches and drops the temperature and the dew point to 40F. Damaging winds are expected at this area as the energetic conditions are very low.
Some storms too will fire in Florida coast but the same lower conditions are there.

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