June 22, 2024

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ENHANCED SEVERE WEATHER RISK SYNOPSIS…ISSUED APR. 18, 2024…10:50 A.M. EDT

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Disclaimer:  This is not affiliated with the National Hurricane Center, Hurricane Hunters, Storm Prediction Center, or National Weather Service.  ALL forecasts herein are the result of my analysis, (to which you will see me at times, insert excerpts from various agencies due to the nature of the importance of the information) and I am solely responsible for the content.  As ALWAYS, follow the National Hurricane Center, National Weather Service, and your local Emergency Management officials for emergency decisions.  In addition, this is strictly a FORECAST OFFICE.  I CANNOT make decisions regarding travel plans, etc.  My purpose, is to provide you the information, based solely on information I analyze, and the accuracy of the information at hand of the time of analysis, so you may make informed decisions.
(T. F. “Storm” Walsh)

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I will reiterate, my forecasts are based on the available information at the time of analysis, and are only as accurate as the information analyzed and the solutions provided.

The outlined maps you were used to seeing from my F5 DATA software, are no longer around and operational.  This means I have lost quite a bit of data to analyze but I will try to make the severe weather forecasts as accurate and understandable as possible.
https://www.spc.noaa.gov/new/images/SPC_outlook_final_updated.png
CATEGORICAL OUTLOOK CONVERSION TABLE FOR DAY 1 OUTLOOKS
image002day1.conv

The Storm Prediction Center (SPC), has issued an ENHANCED risk of severe thunderstorms: MAINLY THIS AFTERNOON INTO EARLY TONIGHT FOR PARTS OF THE MID MS AND LOWER OH VALLEYS…

…SPC SUMMARY…
Damaging gusts to 70 mph, large hail in excess of 2 inches in diameter, and a couple of tornadoes are expected mainly this afternoon into early tonight across the middle Mississippi and lower Ohio Valleys. More isolated large hail and damaging winds will be possible farther south from northern Mississippi and Arkansas into central Texas.

SPC DAY 1 SEVERE THUNDERSTORM OUTLOOK MAPS (first image linked to current SPC outlook.  Click for any updated outlook maps)
day1otlk_1300
TORNADO PROBABILITY
day1probotlk_1300_torn
Probability of a tornado within 25 miles of a point. 

HAIL PROBABILITY
day1probotlk_1300_hail
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.
DAMAGING THUNDERSTORM WINDS PROBABILITY
day1probotlk_1300_wind
Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point.
Based on my analysis of the current outlook, CIPS, NAM 3km, and SPC SREF forecast models, information derived from forecast indices indicate all severe threats are probable.  Based on the complexity of the forecast, I highly recommend reading the outlook text.  The highest threat at time of analysis appears to be tornado activity, significant hail, and damaging wind gusts.  Tornadoes will be a threat mainly within the ENHANCED and a portion of the surrounding SLIGHT risk area.  The peak of the intensity, time of initiation, and peak of the forecast indices, mainly over the ENHANCED risk area should be between 1:00 p.m. – 7:00 p.m. CDT.  Based on analyzed forecast CAPE values, lifted index values, and moderate to steep mid level lapse rates, combined with what appears to be borderline moderate deep layer shear, should produce significant hail over the SPC hatched areas.  Once again, we have a setup similar to yesterday.  Indices posted are for the ENHANCED outline for the Ohio Valley region.  While the forecast STP indices appear to extend further south toward the Arkansas and Texas outline, analyzed SRH values over the Arkansas and Texas areas were very low (0-1km SRH <100 ms2/ms2 and 0-3km SRH <250 ms2/ms2), thus I’m suspecting this is why a tornado outline of only 2% was issued.  Tornadoes for both regions should remain on the weak end.  Based on analyzed MLCAPE values for both the Ohio valley region and over the Texas outline, lifted index, and borderline moderate deep layer shear, significant hail ranging from 1.5 – 2.5 inches should be expected.   The following were the forecast parameters and indices analyzed this morning, and pertain to the ENHANCED risk area.  Bear in mind, indices recorded below are at the time of peak intensity.  Indices meanings can be accessed further on in the synopsis:
SBCAPE: 2000 – 3000 j/kg-1
MLCAPE: 1500 –3000 j/kg-1 (2500 – 3500+ for TX)
MUCAPE: 2500 – 3000 j/kg-1
SRH 0 -1 km: <150 – 150 m2/s2
SRH 0 -3 km: 150 – 200 m2/s2
SRH EFFECTIVE: 150 – 200 m2/s2

L. I.: -4 to -7
STP: 1 – 3
SCP: 2 – 8
0 -6 km SHEAR: 35 – 40 kts
EFF. SHEAR: 30 – 35 kts
MID LEVEL LAPSE RATE: 6.5 – 7.0C (7.5 – 8.0C TX region)
DEWPOINT: 60F – 70F (70F – 74F TX region)
EHI: 1.8 – 2.9
TOTAL TOTALS INDEX: 49 – 50C
K INDEX: 26 – 32C
SWEAT INDEX:
350 – 425

STP ( Significant Tornado Parameter) EXPLAINED:
A majority of significant tornadoes (EF2 or greater damage) have been associated with STP values greater than 1, while most non-tornadic supercells have been associated with values less than 1 in a large sample of RAP analysis proximity soundings.

SCP (Supercell Composite Parameter) EXPLAINED:
A multiple ingredient, composite index that includes effective storm-relative helicity (ESRH, based on Bunkers right supercell motion), most unstable parcel CAPE (muCAPE) and convective inhibition (muCIN), and effective bulk wind difference (EBWD). Each ingredient is normalized to supercell “threshold” values, and larger values of SCP denote greater “overlap” in the three supercell ingredients. Only positive values of SCP are displayed, which correspond to environments favoring right-moving (cyclonic) supercells.

SWEAT INDEX
Screenshot 2024-03-30 at 09-30-56 SWEAT Index

The following are the SCP (Supercell Composite Parameter) and STP (Significant Tornado Parameter) forecast maps from the NAM model.  Generally, the higher the values and brighter the color, indicates a greater probability of strong thunderstorm and tornadic activity over an area:
NAM 3KM SCP FORECAST (1:00 p.m. 18 APR.  – MIDNIGHT CDT 19 APR.)
nam-nest-central-supercell_comp-1713420000-1713463200-1713502800-80
NAM 3KM STP FORECAST
(1:00 p.m. 18 APR. – MIDNIGHT CDT 19 APR.)
nam-nest-central-sig_tor-1713420000-1713463200-1713502800-80

SPC SREF SIGNIFICANT TORNADO PARAMETER >1 FORECAST 21Z
SREF_prob_sigtor_1__f012
This is from the 00Z update from NADOCAST.  Click on the image for the updates page.  Once there, click on the time on the left (i.e. 12Z), then scroll to this (i.e. nadocast_2022_models_conus_sig_tornado_abs_calib_20240418_t00z_f12-35.png)
nadocast_2022_models_conus_sig_tornado_abs_calib_20240418_t00z_f12-35
Please use the following maps, which should update automatically, for Mesoscale Discussions and Convective Watches.  You may have to refresh your browser, or click on the graphics.  I have provided the SPC homepage link below, so you may get the updated information regarding any changes to the outlook:
SPC MESOSCALE DISCUSSIONS (CLICK IMAGE FOR UPDATES)
Valid MD Image
SPC CONVECTIVE WATCHES (CLICK IMAGE FOR UPDATES)
Valid WW Image
IF A TORNADO WARNING IS ISSUED FOR YOUR AREA, IMMEDIATELY TAKE STURDY
AND SAFE SHELTER

The following sites will explain most of the severe weather and tornado values listed above, and will give you an idea of what to expect:
ENVIRONMENTAL INDICES AND PARAMETERS NWS
https://www.weather.gov/lmk/indices

THE WEATHER PREDICTION
http://www.theweatherprediction.com/severe/indices/

SPC HOMEPAGE LINK
https://www.spc.noaa.gov/classic.html

The following NWS Watch / Warning map will provide local NWS information for your area.  Click the image, then once it refreshes, click on your area of interest to view any special weather statements, hazards or advisories for your area.
NWS WATCH / WARNING DISPLAY (LINKED…CLICK MAP, THEN YOUR AREA)

NWS DOPPLER RADAR LOOP (LINKED, CLICK RADAR MAP)
canvas.radr_.us_
RAP RADAR (CLICK IMAGE THEN GO TO LOOP DURATION AND PICK LENGTH OF LOOP, THEN CLICK RADAR SITE)
CARIBBEAN RADAR (CLICK IMAGE TO ACCESS ANIMATION)
radar_comp_Eng
You may direct any questions by contacting me personally, ANYTIME, at: twalsh22000@yahoo.com

Have a blessed day!

T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST /SEVERE WEATHER SPECIALIST

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.

palmharborforecastcenter

2024-04-18 14:43:09

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