645
FXUS64 KMEG 181745 AAA
AFDMEG
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MEMPHIS TN
1145 AM CST WED DEC 18 2024
..NEW AVIATION
UPDATE
ISSUED AT 1000 AM CST WED DEC 18 2024
SHOWERS CONTINUE TO IMPACT AREAS SOUTH OF I-40 THIS MORNING WITH
THE MOST ROBUST CONVECTION CURRENTLY LOCATED OVER NORTHERN
ALABAMA. EXPECT SHOWERS TO LINGER THROUGH THE AFTERNOON. THE
FLOOD WATCH HAS BEEN CANCELLED DUE TO THE BULK OF PRECIPITATION
MOVING OUT OF THE AREA OF CONCERN. TEMPERATURES WILL GRADUALLY
DECREASE BEHIND THIS MORNING'S FRONTAL PASSAGE WITH OVERNIGHT LOWS
DIVING INTO THE LOW AND MID 30S.
ANS
SYNOPSIS
ISSUED AT 320 AM CST WED DEC 18 2024
STORMS, SOME STRONG TO SEVERE, WILL MOVE THROUGH THE MID-SOUTH
THIS MORNING ALONG A COLD FRONT. BY TOMORROW, WEATHER WILL COOL
DOWN BEHIND THE FRONT, BEGINNING A COOLING TREND FOR THE REST OF
THE WEEK. LOWS WILL FALL BACK INTO THE 20S THIS WEEKEND.
HIGH AND LOW TEMPERATURES ARE EXPECTED TO WARM AGAIN BY THE
MIDDLE OF NEXT WEEK.
DISCUSSION
(TODAY THROUGH TUESDAY)
ISSUED AT 320 AM CST WED DEC 18 2024
A COLD FRONT IS CURRENTLY MOVING INTO THE REGION AHEAD OF A
DEEPENING SHORTWAVE TROUGH OVER THE CENTRAL CONUS. TO THE EAST, A
WARM FRONT CURRENTLY SITS OVER SOUTH MISSOURI INTO KENTUCKY. ALONG
THESE FRONTS, ELEVATED INSTABILITY HAS ALLOWED DISORGANIZED
CONVECTION TO FORM THIS MORNING. WITH TIME, THIS CONVECTION WILL
MOVE EAST, BRINGING SHOWERS AND STORMS THIS MORNING THAT WILL MOVE
THROUGH THE REGION TODAY.
STORM STRUCTURE AND INTENSITY STILL APPEARS TO BE
MARGINAL/DISORGANIZED WITH THIS LINE AS IT TRAVERSES THE REGION
TODAY. FORECAST HREF/RAP SOUNDINGS DISPLAY A MODESTLY UNSTABLE
ENVIRONMENT OVER WEST TENNESSEE THIS MORNING OF 750 - 1000 J/KG
MUCAPE AND EFFECTIVE SHEAR OF 30 - 40 KNOTS FROM THE WEST.
HODOGRAPHS DO DISPLAY DECENT 0-1 AND 0-3 KM SRH (~200 M2/S2), BUT
SURFACE INSTABILITY IS LIKELY TO REMAIN LIMITED BELOW 250 J/KG
WITH A STOUT SURFACE INVERSION, HAMPERING ANY TORNADO THREAT.
OVERALL, EXPECT A LINE OF STORMS TO MOVE THROUGH THIS MORNING AND
AFTERNOON WITH DAMAGING WINDS AND HAIL BEING THE PRIMARY THREATS.
ANOTHER ASPECT OF THIS FRONTAL PASSAGE IS THE AMOUNT OF RAIN THAT
WILL FALL OVER NORTHERN PORTIONS OF THE CWA. TRAINING STORMS
ALONG THIS LINE COULD PRODUCE RAIN RATES OF UP TO AN INCH PER
HOUR. LATEST HREF/HRRR GUIDANCE PRODUCE A SWATH OF 1-2 INCHES OF
RAINFALL ACROSS WEST TENNESSEE THROUGH TODAY WITHIN THESE AREAS.
WITH SATURATED SOILS FROM RECENT RAINS, SOME STREAMS COULD RISE
QUICKLY WITHIN HEAVIER BOUTS OF RAINFALL. THEREFORE, A FLOOD WATCH
IS CURRENTLY IN EFFECT THROUGH 18Z TODAY.
THE COLD FRONT WILL EVENTUALLY PASS TO OUR SOUTH TONIGHT,
ADVECTING COLDER AIR IN AS THE SHORTWAVE TROUGH EXITS TO OUR EAST. THE
UPPER PATTERN BECOMES MUCH MORE NORTHWESTERLY THROUGH THE END OF
THE WEEK SUPPORTING A SUBSEQUENT REINFORCING COLD FRONTAL PASSAGE
FRIDAY. BY SATURDAY, LOWS DROP TO BELOW 30 WITH HIGHS IN THE 40S,
LASTING THROUGH MONDAY. ENSEMBLES ARE IN GOOD AGREEMENT THAT
UPPER NORTHWESTERLIES WILL GIVE WAY TO A ZONAL, PROGRESSIVE
PATTERN CONTAINING A SERIES OF SHORTWAVES AND A GENERAL WARM-UP BY
MID-WEEK. HOWEVER, CONFIDENCE STILL REMAINS LOW REGARDING THE
DEPICTION OF SURFACE FEATURES THAT WILL BE CRITICAL TO DETERMINING
OUR IMPACTS.
AVIATION
(18Z TAFS)
ISSUED AT 1145 AM CST WED DEC 18 2024
A FEW MORE HOURS OF SHRA REMAIN AT TUP, BEFORE LIFTING OUT WITH A
PROGRESSIVE COLD FRONT. GUSTY NORTH POST FRONTAL WINDS WILL
OTHERWISE PREVAIL AREAWIDE.
PRIMARY FORECAST CONCERN REMAINS POST-FRONTAL CIGS. GOES VISIBLE
IMAGERY SHOWED AN AREA OF CLEARING OVER SOUTHERN MO LATE THIS
MORNING. ABOUT 100 MILES NORTH, AN MVFR DECK WAS DROPPING SOUTH
INTO CENTRAL MO. RESIDUAL MOISTURE IN THE CLEARING AREA MAY FILL
BACK IN AS MVFR CIGS, AS THIS AIRMASS MOVES INTO THE MIDSOUTH
TONIGHT.
LOW LEVEL PRESSURE GRADIENT WILL EASE TONIGHT AS HIGH PRESSURE
SETTLES IN BY 12Z. EXPECT LIMITED SURFACE WIND IMPACTS FOR LATE
EVENING AND OVERNIGHT OPERATIONS AT MEM.
PWB
MEG WATCHES/WARNINGS/ADVISORIES
AR...NONE.
MO...NONE.
MS...NONE.
TN...NONE.
PUBLIC FORECAST...JAB
AVIATION...PWB
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