507
FXUS64 KMEG 282137
AFDMEG
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEMPHIS TN
337 PM CST MON NOV 28 2022
..NEW DISCUSSION
DISCUSSION
(THIS EVENING THROUGH NEXT SUNDAY)
ISSUED AT 336 PM CST MON NOV 28 2022
A POTENTIAL HIGH-END SEVERE WEATHER EVENT REMAINS ON TRACK TO
IMPACT THE MIDSOUTH ON TUESDAY AND TUESDAY NIGHT. TORNADOES, A
FEW STRONG AND LONG-LIVED, WILL BE POSSIBLE.
LOW LEVEL MOISTURE AND INSTABILITY WILL SURGE NORTH THROUGH THE
LOWER MS RIVER VALLEY TUESDAY MORNING, IN ADVANCE OF A DEEPENING
UPPER LEVEL LONGWAVE TROF OVER THE GREAT PLAINS. INITIAL ROUND OF
LATE MORNING/EARLY AFTERNOON STORMS WILL LIKELY ROOT IN AN ELEVATED
LAYER, ASSOCIATED WITH A 925MB WARM FRONT SURGING NORTH FROM THE
ARKLAMISS. THESE STORMS WILL LIKELY PRESENT A MARGINAL SEVERE
THREAT IN THE EARLY AFTERNOON, WITH MIDLEVEL LAPSE RATES OF 6.5
C/KM ACCOMPANYING MUCAPE BELOW 300 J/KG.
THE POTENTIAL FOR STORMS TO BECOME ROOTED IN A NEAR-SURFACE LAYER
WILL INCREASE MID TO LATE AFTERNOON, AIDED BY MODEST SURFACE
HEATING AND DEWPOINTS RAPIDLY WARMING INTO THE MID/UPPER 60S.
DURING THIS PERIOD, CONVECTION-ALLOWING MODEL (CAM) CONSENSUS
DEPICTS 850MB WIND INCREASING FROM 40 TO 60 KTS, ELONGATING
HODOGRAPHS AND INCREASING 0-3KM HELICITY TO VALUES IN EXCESS OF
500 M2/S2.
UNCERTAINTY REMAINS REGARDING THE EXTENT AND TIMING OF LOW LEVEL
INVERSION EROSION IN THE ABSENCE OF STRONG SURFACE HEATING. THIS
WILL LARGELY DETERMINE THE NORTHWARD EXTENT OF THE TORNADO THREAT
IN THE LATE AFTERNOON, PRIOR TO STEEP MIDLEVEL HEIGHT FALLS.
WHILE SOME UNCERTAINTY REMAINS REGARDING THE ONSET TIMING OF
SURFACE-BASED CONVECTION AND ASSOCIATED TORNADO THREAT, THE
PARAMETER SPACE WILL BECOME QUITE CONCERNING BY EARLY TUESDAY
EVENING, AIDED BY CAPE IN EXCESS OF 1000 J/KG AND STEEP HEIGHT
FALLS AND STRONGLY BOWED HODOGRAPHS. LOW LCLS (CLOUD BASES) AND
STORM MOVEMENT IN EXCESS OF 60 MPH WILL MAKE FOR PARTICULARLY
DANGEROUS CONVECTIVE ENVIRONMENT, WHERE TORNADIC STORMS APPEAR TO
ARRIVE SUDDENLY, PRECEDED BY LITTLE IF ANY VISUAL OR AUDIBLE
NOTICE. DEFINITELY A TIME TO KEEP A WEATHER RADIO WITH BATTERY
BACKUP AND A FULLY-CHARGED CELL PHONE NEARBY.
BEYOND TUESDAY'S SEVERE EVENT, GENERALLY QUIET WEATHER IS
FORECAST FROM THROUGH THE UPCOMING WEEKEND, UNDER FAST ZONAL FLOW
ALOFT. A NORTHERN BRANCH UPPER LOW WILL PASS THROUGH THE GREAT
LAKES ON ON SATURDAY, MODESTLY DEPRESSING MIDLEVEL HEIGHTS OVER
THE MIDSOUTH AND AIDING THE PASSAGE OF A PACIFIC COLD FRONT. A FEW
SHOWERS WILL ACCOMPANY THE FRONTAL PASSAGE, WITH ONLY LIMITED
CHANCES FOR THUNDER.
PWB
AVIATION
(18Z TAFS)
ISSUED AT 1138 AM CST MON NOV 28 2022
CLEAR SKIES AND SOUTHEAST WINDS AT 08-10KTS ARE EXPECTED THROUGH
THIS EVENING. BY NIGHTFALL, EXPECT A HIGH DECK OF CLOUDS TO MOVE
IN AND FOR WINDS TO SLOW TO 03-05KTS. EXPECT RAPIDLY CHANGING
CONDITIONS STARTING TOMORROW AS A STRONG COLD FRONT MOVES CLOSER
TO THE REGION. THERE IS POTENTIAL FOR 40KT WIND SHEAR DEVELOPMENT
AT JBR OVERNIGHT AS A LOW LEVEL JET MOVES OVER THE REGION.
FOR NOW, THE LLJ LOOKS TO STAY WEST OF MEM, SO LEFT THIS OUT OF
TAF FOR NOW. HOWEVER, THERE IS POTENTIAL FOR THE LLJ TO MOVE
SLIGHTLY EAST. GUIDANCES CONTINUE TO SUGGEST THE DEVELOPMENT OF
SHOWERS ACROSS MOST SITES BY LATE MORNING IN ADDITION TO MVFR
CIGS.
ANS
MEG WATCHES/WARNINGS/ADVISORIES
AR...NONE.
MO...NONE.
MS...NONE.
TN...NONE.
PUBLIC FORECAST...PWB
AVIATION...ANS
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