SEVERE THUNDERSTORM SLIGHT RISK FORECAST SYNOPSIS…ISSUED 3:30 P.M. CST…FEB. 19, 2017

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(T. F. “Storm” Walsh III)

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Good day everyone!

The Storm Prediction Center (SPC) has designated the following risk areas regarding Severe Thunderstorms for this afternoon, into tonight:

…THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS A LARGE PART OF CENTRAL TEXAS INTO SOUTHERN OKLAHOMA…

…THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE SOUTHERN PLAINS SURROUNDING THE SLIGHT RISK…

…SUMMARY…
Severe thunderstorms are possible across parts of the southern Plains late today and this evening, developing farther southward across the Texas Hill Country and south Texas tonight. Large hail and sporadic wind damage are possible, and a tornado or two could occur.

SPC DAY 1 CONVECTIVE OUTLOOK MAPS
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From the SPC outlook:

…Synopsis…
A southern-stream upper low presently over the southern Rockies at late morning will gradually progress generally eastward over the next 24 hours, essentially evolving into split streams with one portion approaching the central High Plains and the other overspreading northern Mexico.

…Southern Plains… Ahead of the previously described evolving upper system, near 60F surface dewpoints continue to develop northward, as far north as the Red River vicinity as of 16Z, while middle/upper 60s F surface dewpoints are semi-prevalent along the TX coast and Hill Country. This amplified/meridional large-scale pattern will continue to yield ample higher-level cloud cover, which casts some uncertainty on pockets of stronger heating/destabilization coincident with otherwise moistening boundary layer.

Regardless, indications are that the potential for surface-based thunderstorms should initially be focused late this afternoon/early evening across parts of western North Texas into southwest/south-central OK. Presuming some cloud breaks/modest destabilization, wind profiles/low-level hodographs would support initial supercells potentially including a hail/tornado risk, although with time, flow weakness around 700 mb is suggestive of a messy and more linear mode by early into mid-evening.

Farther south, with the arrival of large-scale forcing for ascent, bands of scattered storms seems likely to increase late this evening into the overnight across the Hill Country and Rio Grande vicinity. Some hail will initially be possible, but damaging winds should be the primary risk given forecast wind profiles.

Based on analysis of forecast sounding data from F5 DATA software from both the RAP and NAM-WRF models, with initial verification of current Mesoanalysis, the forecast sounding data suggests hail and damaging thunderstorm gusts / straight line winds to be the primary threat.  Models suggest the best chance for this activity to be somewhat further east than shown in the SPC outlook outlines.  Hail within the F5 DATA outlines may not wind up being significant, based on lifted indices of -2 to -4, however hail within the SPC outlines could be significant and large, as lifted indices increase to -4 to a small area of -8.  Both model solutions as far as SBCAPE suggest CAPE values ranging from 1000- 2000 j/kg, mainly from 3:00 p.m. CST through early evening.  The following outlines from the RAP and NAM-WRF indicate where the strongest supercells / severe thunderstorms have the best probability of occurring, and the greatest probability of stronger cells producing isolated tornadoes.  Based on current forecast indices, values are not indicating strong tornadoes to occur.  The RAP model outline is indicative for 2:00 p.m. CST, and the NAM-WRF for 3:00 p.m. and 6:00 p.m. through 8:00 p.m.CST

RAP BEST SEVERE/TORNADO PROBABILITY 2:00 P.M. CST
f5data-rap

NAM – WRF BEST SEVERE/TORNADO PROBABILITY 3:00 P.M. CSTf5data-nam-2

NAM – WRF 6:00 P.M. CST
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Residents under mainly the slight risk area should monitor NOAA Weather Radio throughout the afternoon into tonight, and local NWS statements and warnings.

IF A TORNADO WARNING IS ISSUED FOR YOUR AREA…SEEK SHELTER IMMEDIATELY.

As a reminder, ALL of the following graphics are linked to their respective sites.  The graphics will not update automatically on this site.  You must mouse over and click on the graphic for real time updates.  The NWS Hazard and Warning map will provide you current NWS information by clicking on the map, then clicking on your area.

SPC CONVECTIVE WATCHES DISPLAY
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SPC MESOSCALE DISCUSSIONS DISPLAY
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NWS HAZARDS AND WARNINGS DISPLAY
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INTELLICAST NWS DOPPLER RADARusa_none_anim

INTELLICAST NWS DOPPLER RADAR SUMMARY
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Have a blessed day!

T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST /SEVERE WEATHER SPECIALIST
MEMBER WEST CENTRAL FLORIDA AMS
CoCoRAHS OBSERVER

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About palmharborforecastcenter

I am a Tropical Forecast meteorologist, providing hurricane forecasts during the Atlantic Hurricane Season. I retired from the U.S. Coast Guard in July of 2001. Meteorology became my passion in high school, and I have continued my educational background in meteorology since 1996, when I undertook the study of Tropical Meteorology. While working toward my degree, I had to unexpectedly withdraw from college due to my oldest sons medical reasons. I do however, meet the educational criteria of the AMS to be recognized as a meteorologist. Studies include, but are not limited to the Navy Aerographers Mate course, Naval METOC meteorology course, Meteorology 2010 Sophomore level course while attending St. Petersburg College, Clearwater, FL., Basic Forecasting course for operational meteorologists from Rapid WX, meteorology institute, a four month meteorological internship, and extensive research on numerous meteorological topics such as the MJO, NAO, satellite imagery interpretation, etc. I have been forecasting Tropical Weather (Tropical Storms and Hurricanes) since 1996, with my main client being three different Coast Guard Commands.
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