MODERATE SEVERE WEATHER THREAT FORECAST SYNOPSIS…PWO ISSUED BY SPC…APR. 26, 2017…1:50 P.M. EDT

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(T. F. “Storm” Walsh III)

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Good day everyone!

The SPC has designated the following severe weather risk areas in the Day 1 Outlook as of the 1630Z issuance:

SPC DAY 1 CONVECTIVE OUTLOOK MAPS


Probability of a tornado within 25 miles of a point.
Hatched Area: 10% or greater probability of EF2 – EF5 tornadoes within 25 miles of a point.

Probability of one inch diameter hail or larger within 25 miles of a point.
Hatched Area: 10% or greater probability of two inch diameter hail or larger within 25 miles of a point.

…THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS OVER PARTS OF SOUTHERN AR AND NORTHERN LA…

…THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM SOUTHEAST MO INTO PARTS OF AR…TN…LA…MS…AND TX…

…THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM SOUTHERN IL INTO THE LOWER MS VALLEY…

…THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER MUCH OF THE MIDDLE AND LOWER MS VALLEY…

...SPC SUMMARY…
Severe thunderstorms are expected across the Lower Mississippi Valley. Tornadoes, large hail, and damaging winds are most probable from northeast Texas across parts of Arkansas and northern Louisiana this afternoon. Isolated severe thunderstorms may extend as far north as Illinois/Indiana this afternoon and evening, and into the central Gulf States during the overnight hours.

…Lower MS Valley… Few changes have been made to the ongoing forecast. A squall line currently extends from south-central MO into northeast TX. Several bowing structures along this line will pose a risk of damaging winds gusts, large hail, and perhaps a QLCS tornado or two this afternoon. The activity will likely spread into southeast MO and western KY/TN by early evening, with a continued severe threat.

Farther south, most model solutions suggest that the capping inversion will slowly weaken this afternoon. This should help to allow a few discrete storms to form in the warm sector ahead of the more organized convective line. Local VAD and forecast hodographs in this region continue to support a risk of supercells capable of tornadoes (some strong) if discrete initiation materializes. Therefore will maintain the MDT risk and 15% tornado forecast. These storms are expected to track northeastward through the evening into western/central MS where damaging winds and isolated tornadoes will remain possible.

Overnight, it is uncertain how far east the organized severe threat will persist. Nevertheless, will make no changes to the eastern extent of the SLGT risk at this time.

A Public Severe Weather Outlook is in effect:

PUBLIC SEVERE WEATHER OUTLOOK

NWS STORM PREDICTION CENTER
NORMAN OK 1142 AM CDT WED APR 26 2017
…Severe thunderstorms expected over parts of the lower Mississippi Valley this afternoon and tonight…

* LOCATIONS...
Central and southern Arkansas Northern Louisiana Northwest Mississippi Northeast Texas

* HAZARDS… Several tornadoes, a few intense Scattered large hail, some baseball size Scattered damaging winds

* SUMMARY… Severe thunderstorms are expected across the Lower Mississippi Valley. Tornadoes, large hail, and damaging winds are most probable from northeast Texas across parts of Arkansas and northern Louisiana this afternoon. Isolated severe thunderstorms may extend as far north as Illinois/Indiana this afternoon and evening, and into the central Gulf States during the overnight hours.

Preparedness actions…
Review your severe weather safety procedures for the possibility of dangerous weather today. Stay tuned to NOAA Weather Radio, weather.gov, or other media for watches and warnings. A tornado watch means that conditions are favorable for tornadoes to form during the next several hours. If a tornado warning is issued for your area, move to a place of safety, ideally in a basement or interior room on the lowest floor of a sturdy building. &&
..Dean.. 04/26/2017

Based on analysis of the SPC outlook, and forecast sounding data provided by the NAM-WRF regional model, via F5 DATA Severe Weather software, output of various severe weather and tornado indices while this situation will occur within the SPC outlines, it is suggested by the model solution that the severe / tornado threat may extend further south.  The following outlines suggest where the greatest probability for severe thunderstorms, tornadoes, and strongest of the severe weather may occur.  Based on various tornado forecast indices, some isolated tornadoes within the stronger supercells may be strong and long track.  Based on the modeling, initiation of the most severe weather should occur shortly, approximately 1:00 p.m. CDT and continue through to approximately 4:00 – 5:00 p.m. CDT.  The modeling suggests thereafter, at approximately 7:00 p.m. CDT, this activity may spread into western / west-central MS.

NAM-WRF 1:00 P.M. CDT SEVERE OUTLINE

NAM WRF 4:00 P.M. CDT SEVERE OUTLINE

NAM-WRF 7:00 P.M. CDT SEVERE OUTLINE

Residents in the outlined SPC MODERATE and ENHANCED risk areas, should monitor NOAA Weather Radio, and local NWS statements for up to date information regarding any necessary actions.

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

The following graphics are linked to their respective sites.  Mouse over and click on the graphics for up to date information.

SPC CONVECTIVE WATCH DISPLAY

SPC MESOSCALE DISCUSSIONS DISPLAY

NWS DOPPLER RADAR SITE MAP

INTELLICAST RADAR SUMMARY (Click local area once map displays to zoom in)

NWS HAZARDS AND WARNINGS DISPLAY (click on graphic, then your area of interest)

I work tomorrow, but intend to have an update for the severe weather forecast for Friday with SPC indicating an ENHANCED risk.

I will probably be updating my 2017 Atlantic Hurricane Season Outlook, and have it posted mid to late May.  ALL the climate models have updated, and if current suggested information is accurate, we may not see El Nino this season, but neutral, warm biased conditions, to possibly an El Nino Modoki.

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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5 Responses to MODERATE SEVERE WEATHER THREAT FORECAST SYNOPSIS…PWO ISSUED BY SPC…APR. 26, 2017…1:50 P.M. EDT

  1. originallt says:

    Thanks, Storm!

  2. Greg Goodman says:

    Thankyou Mr storm for all of your hard work.

  3. dellamom says:

    Thank you, Storm. Prayers to all in harm’s way.

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