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[Printable]
650
FXUS64 KMEG 231130
AFDMEG

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEMPHIS TN
530 AM CST SUN NOV 23 2014

.UPDATE...

UPDATED FOR 12Z AVIATION DISCUSSION BELOW.

&&

.PREV DISCUSSION... /ISSUED 438 AM CST SUN NOV 23 2014/

EARLY THIS MORNING...A MESOSCALE CONVECTIVE SYSTEM WAS MOVING
EASTWARD ALONG THE NORTHWEST GULF AHEAD OF A STRONG UPPER LEVEL
TROUGH. MOST OF THE MIDSOUTH REMAINED RAIN FREE WITH JUST SOME
PATCHY LIGHT RAIN. A WEAK FRONT EXTENDED ACROSS NORTHEAST AR AND THE
MO BOOTHEEL. SOUTHEAST WINDS WERE PUSHING MILDER AIR INTO THE AREA
TO THE SOUTHEAST OF THE FRONT WITH SOME TEMPERATURES NEAR THE 60
DEGREE MARK.

THE UPPER LEVEL TROUGH WILL MOVE EAST NORTHEASTWARD ACROSS THE
MIDSOUTH TODAY WITH A STRENGTHENING SURFACE LOW TO OUR WEST. THE GFS
INDICATES A 987 MB LOW OVER SOUTHWEST MO AT SUNSET WHILE THE ECMWF
HAS THE PRESSURE AT 992 MB. MODELS ARE STILL SHOWING WIDESPREAD
SHOWERS MOVING QUICKLY INTO THE MIDSOUTH FROM THE SOUTHWEST TODAY.
THE HRRR MODEL INDICATES THAT THE ENTIRE FORECAST AREA WILL HAVE
SOME RAIN BY NOON THAT WILL THEN PERSIST INTO THE AFTERNOON BEFORE
DIMINISHING FROM THE SOUTHWEST. SHOWERS WILL HELP TO HOLD
TEMPERATURES DOWN. THIS INITIAL UPPER LEVEL TROUGH IS FORECAST TO BE
MOVING TO THE NORTHEAST OF THE REGION BY 6 PM. PRECIPITABLE WATER
VALUES WILL CLIMB TO AROUND 1.5 INCHES TODAY AS SOUTHERLY WINDS
SURFACE AND ALOFT TAP INTO GULF MOISTURE. WILL CONTINUE TO MENTION
THE THREAT OF LOCALLY HEAVY RAINFALL IN THE HAZARDOUS WEATHER
OUTLOOK WITH SOME HEAVY DOWNPOURS. MOST SPOTS ARE EXPECTED TO PICK
UP AROUND AN INCH OF RAIN BUT SOME LOCATIONS MAY SEE 1 1/2 INCHES.
INSTABILITY WILL BE MARGINAL AT BEST WITH THIS SYSTEM FOR MOST OF
OUR AREA. HOWEVER...MODELS DO INDICATE SOME ELEVATED INSTABILITY AND
MAYBE A LITTLE SURFACE BASED INSTABILITY DEVELOPING OVER NORTHEAST
AR AND THE MO BOOTHEEL LATE THIS AFTERNOON AND EVENING. THIS WILL BE
AHEAD OF THE SURFACE LOW OVER MO AND A COLD FRONT TRAILING TO THE
SOUTH. IN ADDITION...DIFFLUENCE ALOFT DEVELOPS OVER THE REGION AHEAD
OF A TRAILING UPPER LEVEL TROUGH. WILL MENTION A FEW STRONG
THUNDERSTORMS FOR THIS AREA LATE THIS AFTERNOON AND EARLY EVENING
WITH STRONG GUSTY WINDS AND SMALL HAIL POSSIBLE...ALTHOUGH A
LIMITING FACTOR WILL BE THAT SURFACE DEW POINTS WILL STRUGGLE TO
EVEN REACH THE 60 DEGREE MARK.

THE COLD FRONT WILL MOVE QUICKLY THROUGH THE MIDSOUTH TONIGHT WITH A
CONTINUED CHANCE OF SHOWERS ACROSS THE AREA. THE BEST CHANCE WILL BE
FROM PORTIONS OF NORTHEAST AR AND THE MO BOOTHEEL INTO PORTIONS OF
NORTHWEST TN WHERE THE BEST UPPER LEVEL DYNAMICS WILL OCCUR WITH
THE SECONDARY UPPER LEVEL TROUGH. WINDS WILL INCREASE AND TURN TO
THE SOUTHWEST AND WEST TONIGHT INTO MONDAY. FOR NOW...HAVE THE WIND
SPEEDS JUST SHY OF NEEDING A WIND ADVISORY FOR A LARGE SECTION OF
THE AREA. WILL ADD TO THE HAZARDOUS WEATHER OUTLOOK THAT A WIND
ADVISORY MAY BECOME NECESSARY. NORTHEAST MS LOOKS TO BE THE AREA
LEAST LIKELY TO NEED A WIND ADVISORY.

COOLER AND DRIER AIR WILL SPREAD INTO THE AREA MONDAY ON BREEZY
WESTERLY WINDS. SKIES WILL BECOME PARTLY TO MOSTLY SUNNY.
TEMPERATURES WILL ONCE AGAIN DROP TO BELOW NORMAL LEVELS AND
CONTINUE THAT WAY FOR AT LEAST A FEW DAYS. KEPT THE FORECAST
PRECIPITATION FREE THROUGH SATURDAY. THE GFS DOES INDICATE A WEAK
CLIPPER TYPE SYSTEM MOVING ACROSS THE AREA WEDNESDAY BUT MOISTURE
LOOKS LIMITED WITH MAINLY JUST AN INCREASE IN MIDDLE LEVEL CLOUDS
EXPECTED.

THE ECMWF AND GFS ARE SIGNIFICANTLY DIFFERENT BEGINNING THANKSGIVING
DAY. THE ECMWF SHOWS MODIFIED ARCTIC AIR SLOWLY PUSHING INTO THE
AREA FROM THE NORTH THURSDAY AFTERNOON THROUGH SATURDAY. THE GFS
PUSHES THE COLD HIGH TO THE EAST WITH WINDS TURNING TO THE SOUTH
ACROSS THE MIDSOUTH. THIS RESULTS IN HUGH DIFFERENCES IN
TEMPERATURES FOR THE REGION...ALTHOUGH CHANCES FOR PRECIPITATION
LOOK SMALL WITH EITHER SCENARIO. FOR NOW...KEPT CLOSE TO THE
EARLIER FORECAST EXCEPT BLENDED THE TEMPERATURES A LITTLE BETTER
WITH SURROUNDING OFFICES.

JCL

.AVIATION...

12Z TAF CYCLE

CIGS WILL CONTINUE TO LOWER EARLY THIS MORNING TO MVFR CONDITIONS
AS A LARGE SHIELD OF RAINFALL APPROACHES FROM THE SOUTHWEST.
MODERATE RAINFALL WILL OVERSPREAD ALL TERMINALS BY
14/15Z...DEPENDING ON THE TERMINAL. INTERMITTENT IFR CONDITIONS
ARE LIKELY AS CIGS CONTINUE TO LOWER IN PRECIP. A GOOD SIGNAL
EXISTS FOR LOWERED VISBYS AS WELL...ESPECIALLY AT TUP WHERE BETTER
LOW LEVEL MOISTURE IS ALREADY IN PLACE. FOR THIS REASON...HAVE
INSERTED BR AT ALL TERMINALS THROUGH 00Z.  BEST CHANCE FOR
THUNDERSTORMS EXISTS AT MKL AND TUP THROUGH THE EARLY
AFTERNOON. ATMOSPHERIC INSTABILITY AT MEM AND JBR DOES NOT LOOK
SUPPORTIVE OF THUNDER MENTION AT THIS TIME...BUT WILL WATCH TRENDS
THROUGH THE MORNING. SLOWLY RAISE CIGS AFTER 03-06Z AT ALL
TERMINALS AS WINDS INCREASE DRAMATICALLY FROM THE WEST WITH COLD
FRONTAL PASSAGE. THIS WILL OCCUR EARLIER AT WESTERN TERMINALS AND
LATER AT EASTERN TERMINALS. WINDS COULD GUST TOWARD 30KTS BEHIND
THE FRONT.

TVT

&&

.MEG WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
MO...NONE.
MS...NONE.
TN...NONE.
&&

$$




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