000
FXUS64 KMEG 221147 AAA
AFDMEG

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MEMPHIS TN
647 AM CDT WED MAY 22 2013

.UPDATE...
UPDATED FOR AVIATION.

&&

.PREV DISCUSSION... /ISSUED 509 AM CDT WED MAY 22 2013/

DISCUSSION...09Z SURFACE ANALYSIS PLACES A SURFACE LOW OVER
EASTERN IOWA WITH A TRAILING COLD FRONT EXTENDING SOUTH ACROSS
MISSOURI...ARKANSAS...AND NORTHEAST TEXAS. KNQA WSR-88D RADAR
TRENDS SHOW THE BACK EDGE OF LAST NIGHT/S CONVECTIVE LINE OF
SHOWERS AND THUNDERSTORMS LOCATED JUST EAST OF THE TENNESSEE RIVER
AND INTO ALABAMA EARLY THIS MORNING. TEMPERATURES AS OF 4 AM CDT
ARE IN THE LOWER TO MIDDLE 60S AT MOST LOCATIONS. PRECIPITATION
CHANCES FOR TODAY THROUGH THURSDAY AND AGAIN FOR LATE THIS WEEKEND
INTO EARLY NEXT WEEK ARE THE PRIMARY FORECAST CHALLENGES THIS
MORNING.

SHORT TERM...(TODAY THROUGH FRIDAY)...SHORT TERM MODELS INDICATE
THE COLD FRONT CURRENTLY LOCATED WEST OF THE MISSISSIPPI RIVER
WILL GRADUALLY MOVE EAST ACROSS THE MID SOUTH TODAY. WATER VAPOR
SATELLITE/UPPER AIR PROFILER TRENDS INDICATE ANOTHER SHORTWAVE
EMBEDDED WITHIN THE UPPER LEVEL TROUGH OVER THE OKLAHOMA PANHANDLE
THIS MORNING. THIS UPPER LEVEL SHORTWAVE AND THE COLD FRONT MAY
RESULT IN THE DEVELOPMENT OF SCATTERED SHOWERS AND THUNDERSTORMS
ACROSS THE MID SOUTH TODAY AND ANY RESIDUAL CHANCES EAST OF THE
MISSISSIPPI RIVER THIS AFTERNOON AS INDICATED BY THE LATEST RUC
AND HRRR. UNTIL THE FRONT PASSES THROUGH THE MID SOUTH...A SMALL
POTENTIAL WILL EXIST FOR PERHAPS A STRONG THUNDERSTORM OR TWO OVER
NORTHEAST MISSISSIPPI THIS AFTERNOON AS INSTABILITY INCREASES UP
TO 2000 J/KG AND 700-500 MB LAYER MID LEVEL LAPSE RATES BECOME
MODERATELY STEEP.

ANOTHER MID LEVEL SHORTWAVE TROUGH AND ASSOCIATED COLD FRONT IS
EXPECTED TO MOVE THROUGH THE MID SOUTH ON THURSDAY. AT THIS
TIME...THINK A POTENTIAL FOR ISOLATED THUNDERSTORMS WILL BE
CONFINED MAINLY TO AREAS ALONG THE TENNESSEE RIVER THURSDAY
AFTERNOON. COOLER AND DRIER AIR IS EXPECTED TO BUILD INTO THE MID
SOUTH FOR THURSDAY NIGHT AND FRIDAY WITH LOWS THURSDAY NIGHT IN
THE 50S AND HIGHS ON FRIDAY IN THE 70S.

LONG TERM...(SATURDAY THROUGH TUESDAY)...00Z GFS/ECMWF LONG TERM
MODEL RUNS INDICATE CONTINUE TO DISAGREE FOR THE UPCOMING WEEKEND
INTO EARLY NEXT WEEK AS A WARM FRONT DEVELOPS ACROSS THE LOWER
MISSISSIPPI VALLEY AND A SUBSEQUENT UPPER LEVEL RIDGE BUILDS ACROSS THE
REGION EARLY NEXT WEEK. RECENT ECMWF MODEL RUNS INDICATE THE FRONT
BECOMING QUASI-STATIONARY ACROSS THE MIDDLE/LOWER MISSISSIPPI
VALLEYS AND THE TENNESSEE VALLEY SUNDAY INTO MONDAY WHILE THE GFS
PLACES THE FRONT ACROSS THE UPPER MIDWEST/NORTHERN MISSOURI DURING
THIS TIME FRAME. THE ECMWF SOLUTION SUGGESTS SEVERAL CHANCES FOR
SHOWERS AND THUNDERSTORMS OVER THE MEMORIAL DAY WEEKEND ARE
POSSIBLE BUT HAVE LEANED THE FORECAST TOWARDS THE OPERATIONAL GFS
WHICH HAS THE SUPPORT OF THE GFS ENSEMBLE MEMBERS. CONSEQUENTLY...WILL
CONTINUE TO KEEP FORECAST DRY FOR NOW UNTIL MODELS COME INTO
BETTER AGREEMENT. A RETURN OF MIDDLE TO UPPER 80 TEMPERATURES ARE
EXPECTED ACROSS THE MID SOUTH FOR SUNDAY THROUGH EARLY NEXT WEEK.

CJC

&&

.AVIATION...
12Z TAFS

RAIN HAD EXITED THE MIDSOUTH AT EARLIER THIS MORNING. HIGH CIGS
HAD HELPED KEEP RADIATIONAL FOG AND LOWER CIG FORMATION TO A
MINIMUM PRIOR TO SUNRISE. GOES WATER VAPOR IMAGERY SHOWED A
SECONDARY UPPER DISTURBANCE CENTERED NEAR FSM AT 11Z. THIS FEATURE
WAS MOVING RATHER QUICKLY EAST...WHICH WOULD PRESENT A LIMITED
TIME WINDOW FOR SHRA/ISOLATED TSRA...MAINLY EAST AND SOUTHEAST OF
MEM THIS MORNING.

LATE TONIGHT WILL BE TOUCH AND GO WITH RESPECT TO FOG FORMATION. GFS
LAMP GUIDANCE DROPS OVERNIGHT DEWPOINTS AND KEEPS WINDS UP SUFFICIENTLY
FOR VFR. HOWEVER...IT APPEARS SURFACE WINDS WILL BE SUFFICIENTLY
LIGHT TO DECOUPLE AFTER 06Z...WITH DRIER AIR FROM AN APPROACHING
COLD FRONT NOT LIKELY TO EDGE IN UNTIL AFTER SUNRISE THURSDAY.

PWB

&&

.PRELIMINARY POINT TEMPS/POPS...
MEM  81  63  83  57 /  30  10  10  10
MKL  79  59  80  51 /  40  10  20  10
JBR  80  59  81  53 /  20  10  10  10
TUP  83  60  84  58 /  50  10  10  10

&&

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

$$