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000
FXUS64 KMEG 171739 AAC
AFDMEG

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MEMPHIS TN
1239 PM CDT FRI MAY 17 2013

.UPDATE...  /ISSUED 1006 AM CDT FRI MAY 17 2013/

SKIES REMAIN CLOUDY OVER MUCH OF THE FORECAST AREA THIS MORNING
WITH TEMPERATURES RANGING FROM THE MID 60S TO LOWER 70S. THE BULK
OF THE RAIN THAT IS FALLING IS OVER EASTERN SECTIONS OF THE
FORECAST AREA. WHILE THERE WILL PROBABLY BE SOME ADDITIONAL
SHOWERS AND THUNDERSTORMS THIS AFTERNOON COVERAGE WILL NOT BE AS
WIDESPREAD OVER WESTERN SECTIONS OF THE FORECAST AREA. HAVE
LOWERED POPS OVER THE WEST FOR THIS AFTERNOON. WHILE TEMPERATURES
HAVE NOT WARMED MUCH SINCE THIS MORNING DUE TO CLOUD COVER AND
RAIN...THERE MAY BE SOME BREAKS IN THE CLOUDS THIS AFTERNOON WHICH
WOULD ALLOW TEMPERATURES TO WARM UP QUICKLY SO WILL NOT MAKE ANY
ADJUSTMENT TO HIGHS AT THIS TIME.

ARS

&&

.PREV DISCUSSION... /ISSUED 440 AM CDT FRI MAY 17 2013/

AN UPPER LEVEL LOW PRESSURE SYSTEM POSITIONED OVER NORTHEAST
ARKANSAS EARLY THIS MORNING WILL CONTINUE TO LIFT NORTHEASTWARD
TODAY. AT THE SURFACE...A 1010MB LOW PRESSURE SYSTEM IN THE
VICINITY OF LITTLE ROCK ARKANSAS WILL ALSO LIFT TO THE NORTHEAST
THROUGH THE DAY. NUMEROUS SHOWERS AND THUNDERSTORMS HAVE DEVELOPED
IN ADVANCE OF THE SURFACE LOW OVER WESTERN PORTIONS OF THE MID
SOUTH AS OF 09Z. THIS ACTIVITY SHOULD CONTINUE TO MOVE NORTHEAST
THROUGH THE MORNING HOURS WITH ADDITIONAL DEVELOPMENT POSSIBLE
THROUGH THE DAY. PLAN TO CONTINUE WITH LIKELY WORDING THROUGH THE
DAY AT ALL LOCATIONS.

SURFACE WINDS IN ADVANCE OF THE SURFACE LOW WILL REMAIN BACKED
WITH DECENT VEERING PROFILES THROUGH THE LOWER AND MIDDLE LEVELS
OF THE ATMOSPHERE. A MID LEVEL JET STREAK ON THE ORDER OF 30-40
KTS WAS SAMPLED FROM 00Z SOUNDINGS AT KLZK...KSHV...AND KJAN.
THIS MID LEVEL JET WILL MAINTAIN A NORTHWESTERLY COMPONENT AND IS
FORECAST TO SPREAD EASTWARD ACROSS SOUTHERN PORTIONS OF THE MID
SOUTH TODAY. DEEP LAYER SHEAR PROFILES ACROSS AREAS SOUTH OF
INTERSTATE 40 SHOULD REMAIN AROUND 30 KTS THROUGH THE
DAY...ALTHOUGH LOW LEVEL SPEED SHEAR SHOULD REMAIN MEAGER. THIS
AMOUNT OF SHEAR WOULD BE SUPPORTIVE OF SOME STORM ORGANIZATION AND
AT LEAST A MARGINAL SEVERE THUNDERSTORM THREAT. A HIGHER LEVEL OF
UNCERTAINTY REMAINS THIS MORNING WITH REGARD TO THE POTENTIAL
SEVERE WEATHER THREAT AS IT WILL BE PREDICATED ON THE DEGREE OF
INSTABILITY THAT CAN DEVELOP. WIDESPREAD CLOUD COVER AND ONGOING
CONVECTION AND EXPECTED RENEWED DEVELOPMENT COULD LIMIT OVERALL
HEATING EVEN AS DEWPOINTS RISE INTO THE MID AND UPPER 60S. THIS
COMPLEX PATTERN MAKES THE POTENTIAL FOR SEVERE STORMS QUITE
UNCERTAIN AND OVERALL CONFIDENCE REMAINS LOW AT THIS TIME. PLAN TO
CONTINUE WITH THE IDEA THAT A FEW STORMS COULD APPROACH SEVERE
LIMITS OVER SOUTHERN AREAS...ESPECIALLY SINCE MUCH OF THE MODEL
GUIDANCE SUPPORTS AFTERNOON SBCAPE VALUES OVER THESE LOCATIONS
BETWEEN 1000-1500 J/KG. CURRENTLY STILL THINK THAT THESE VALUES
MAY BE OVERDONE BY THE MODEL GUIDANCE AND THAT ANY SEVERE WEATHER
THREAT WILL REMAIN ISOLATED. LATER SHIFTS WILL CONTINUE TO MONITOR
THIS POTENTIAL THROUGH THE DAY AND PROVIDE UPDATES AS NECESSARY.

AS THE UPPER LOW MOVES FURTHER NORTHEAST AND DEAMPLIFIES TONIGHT
THE GREATEST CONVECTIVE CHANCES SHOULD SHIFT TO EASTERN SECTIONS
OF THE MID SOUTH. WARM AND HUMID CONDITIONS SHOULD REMAIN IN
PLACE OVERNIGHT.

UPPER LEVEL RIDGING WILL BEGIN TO BUILD EASTWARD INTO WESTERN
PORTIONS OF THE MID SOUTH ON SATURDAY WITH LINGERING TROUGHING
OVER EASTERN SECTIONS. STRONG DAYTIME HEATING WITH TEMPERATURES
RISING INTO THE MID AND UPPER 80S COMBINED WITH DEWPOINTS NEARING
70 DEGREES AND WEAK CAPPING SHOULD RESULT IN THE DEVELOPMENT OF
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS BY SATURDAY
AFTERNOON. THE HIGHEST CHANCES SHOULD REMAIN ACROSS EASTERN
PORTIONS OF THE AREA WHERE THERE IS THE HIGHEST CONFIDENCE FOR CAP
EROSION. MODERATE TO STRONG INSTABILITY WITH SBCAPES IN EXCESS OF
2500 J/KG...LI/S BETWEEN -6C AND -10C...MID LEVEL LAPSE RATES IN
EXCESS OF 7.0 C/KM...COMBINED WITH WEAK DEEP LAYER SHEAR MAY
SUPPORT A FEW PULSE SEVERE STORMS SATURDAY AFTERNOON AND EARLY EVENING.
CONVECTION SHOULD WANE THROUGH THE EVENING HOURS WITH LOSS OF
DAYTIME HEATING.

THE UPPER RIDGE WILL STRENGTHEN FURTHER AND SPREAD EAST ON SUNDAY
BRINGING MAINLY DRY AND INCREASINGLY HOT WEATHER TO THE AREA.
HIGH TEMPERATURES NEARING 90 DEGREES COMBINED WITH UPPER 60S
DEWPOINTS SHOULD MAKE FOR THE HOTTEST DAY SO FAR THIS YEAR. THE
VERY WARM...HUMID...AND DRY WEATHER SHOULD PERSIST THROUGH NEXT
MONDAY.

ANOTHER MID LEVEL SHORTWAVE TROUGH AND ASSOCIATED COLD FRONT WILL
IMPACT THE WEATHER BY NEXT TUESDAY AND WEDNESDAY WITH INCREASING
CHANCES FOR SHOWERS AND THUNDERSTORMS. AS THE SHORTWAVE LIFTS OUT
TO THE NORTHEAST ON THURSDAY...EXPECT THE ASSOCIATED SURFACE FRONT
TO WASH OUT ACROSS THE AREA. UPPER RIDGING SHOULD REBUILD BY THE
END OF NEXT WEEK WITH A RETURN TO DRY WEATHER AND SEASONABLY WARM
TEMPERATURES.

JLH

&&

.AVIATION...

18Z TAF CYCLE (17/18Z-18/18Z)

COMPLICATED FORECAST THIS TAF CYCLE WITH QUITE A BIT OF UNCERTAINTY.
SHOWERS AND FEW THUNDERSTORMS ASSOCIATED WITH AN UPPER LEVEL
DISTURBANCE WILL MOVE EAST OF THE AREA THIS AFTERNOON...AFFECTING
KMKL AND KTUP THROUGH MID-AFTERNOON. IFR CONDITIONS GRADUALLY
IMPROVING FROM THE WEST TO MVFR...THEN BECOMING VFR EARLY THIS
EVENING. WITH LINGERING MOISTURE AND LIGHT WINDS...THINK
CONDITIONS WILL DETERIORATE ONCE AGAIN TO IFR ACROSS THE AREA
AFTER 18/05Z...THEN IMPROVE TO MVFR BY 18Z/14Z AND VFR AROUND
18/16Z. WINDS THIS AFTERNOON S-SW 6-9 KTS. WINDS LIGHT TONIGHT...THEN
S-SW 5-7 KTS AFTER 18/13Z.

JCL

&&

.PRELIMINARY POINT TEMPS/POPS...
MEM  80  69  88  72 /  70  20  20  10
MKL  77  65  84  68 /  70  50  30  20
JBR  78  66  87  69 /  70  20  20  10
TUP  80  67  85  69 /  70  50  30  20

&&

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

$$