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Good day everyone!
I guess I was correct in my assumption of severe weather for portions of the deep south and SE U.S. during the Tue/Wed time frame. I get lucky sometimes. First though, we need to address the Day 1 outlook.
IMPORTANT NOTE: The SPC, at 12:30 p.m. EST, upgraded the risk for Tuesday, Feb. 23, 2016 to a MODERATE risk:
The Storm Prediction Center (SPC) Norman, OK. has designated a SLIGHT risk of Severe Thunderstorms across PORTIONS OF THE RIO GRANDE VALLEY OF TX…
There is a MARGINAL risk across parts of WRN/CENTRAL/SRN TX…
…SUMMARY… NUMEROUS THUNDERSTORMS…SOME WITH LARGE HAIL…ARE EXPECTED ACROSS THE SOUTHERN HIGH PLAINS THIS AFTERNOON AND EVENING…AND ACROSS MUCH OF CENTRAL TEXAS MONDAY NIGHT. ADDITIONALLY…NON-SEVERE THUNDERSTORMS ARE EXPECTED ACROSS THE GULF COAST STATES DURING THE DAY.
Based on analysis of various forecast sounding indices and parameters, the most prominent severe threat should be damaging thunderstorm gusts, and hail. Based on the premise of thunderstorm activity becoming more surface based during the evening, some isolated tornado activity cannot be ruled out. Based on my analysis of various forecast sounding indices from F5 DATA Severe Weather Software, NAM-WRF output related to tornado development, I have extended the tornado threat outline slightly eastward, from what SPC has in the outlook map.
Residents in the risk areas should monitor NOAA Weather Radio, and monitor local NWS and news channels for any statements regarding today’s risk. The following graphics are linked to their respective sites for up to date information. The graphics do not update automatically, so you must mouse over and click on them to retrieve the information.
The SPC has designated an ENHANCED risk of Severe Thunderstorms across portions of SOUTHERN LA/MS/AL AND THE WESTERN FL PANHANDLE…
There is a SLIGHT risk across the UPPER TX COAST TO WESTERN GA AND THE CENTRAL FL PANHANDLE…
There is a MARGINAL risk FROM EASTERN TX TO PARTS OF EASTERN GA AND NORTHERN FL…
...SUMMARY… SEVERE THUNDERSTORMS WITH ALL HAZARDS WILL BE POSSIBLE BEGINNING EARLY TUESDAY IN SOUTHEAST TEXAS AND THEN SPREADING EASTWARD ACROSS LOUISIANA…MISSISSIPPI…ALABAMA AND THE FLORIDA PANHANDLE THROUGH EARLY WEDNESDAY MORNING.
SPC OUTLOOK CATEGORY DESCRIPTIONS
Based on my analysis of the SPC day 2 outlook information, surface and upper air maps, and the most current forecast sounding information from F5 DATA Severe Weather software, using the current NAM-WRF solution, indices reflect pretty much what is contained in the current outlook. There is a very good probability of a severe hail event, as well as numerous tornadoes within the enhanced risk area, although based on current forecast indices, this may not be ruled out over a portion of the slight risk area. Information from a couple of select indices such as the forecast L.I. (Lifted Index) and the EHI (Energy Helicity Index) along with the STP (Significant Tornado Parameter) back up the probabilities. The forecast LI values are -2 to -4 over a majority of the risk area, with isolated areas in the extreme southern portion of the risk areas showing values of -6 to -8.
The STP values are ranging anywhere from 1 to 14 in increments from the northern portion of the area to the southern portions, and EHI values on the order of 1 to 4. STP’s of greater than 1, indicate a much greater increased probability of experiencing the potential of significant tornadoes (EF2-EF5), and EHI values of greater than 3 indicate a probability of strong, long tracked tornadoes could be experienced. However, as of current, this information, along with the maps that follow, should be considered PRELIMINARY as the forecast sounding information will undoubtedly change during the overnight hours, which will reflect a change in forecast soundings, and area coverage. The worst of the severe threat seems to be after early afternoon at the moment, near the beginning of early evening (6:00 p.m. CST?). Initiation however, based on the SPC outlook, could begin early afternoon, sometime after 12:00 noon CST. The outlines reflect where the greatest probability of a significant tornado event could occur.
I am going to try and update in the morning, once the models update with enough information, in which I will be able to analyze the RAP model solution as well.
Have a blessed day!
T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST /SEVERE WEATHER SPECIALIST
MEMBER WEST CENTRAL FLORIDA AMS