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000
FXUS64 KJAN 191457 AAA
AFDJAN

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JACKSON MS
957 AM CDT SUN MAY 19 2013

.UPDATE...LATEST SATELLITE IMAGERY SHOWED THE REGION UNDER THE
INFLUENCE OF A SHORTWAVE RIDGE WITH WEAK MOISTURE CONVERGENCE...WHICH WAS
BEING FLANKED BY A STRONG UPPER TROUGH OVER THE PLAINS AND SHORT
WAVE TROUGHING OVER THE SOUTHEAST US. STRATUS WAS NOTED OVER THE
REGION THIS MORNING...WHICH WILL LIFT FOR THIS AFTERNOON FOR PARTLY
CLOUDY SKIES WITH HIGH DEBRIS CLOUDS COMING FROM THE PLAINS SYSTEM.
AREA SOUNDINGS SHOWED GOOD LAPSE RATES ACROSS THE REGION OF AROUND
8C...WITH CAPES AROUND 2000...WITH GOOD DRYING FROM 900 TO AROUND
500 MB ABOVE THE LOW LEVEL MOIST BOUNDARY LAYER. DCAPES ACROSS THE
SOUTH WERE AROUND 1200 WITH COLD POOL HEIGHT AT 598 MB AT 61F. PWATS
WERE GENERALLY AROUND 1.2 INCHES . LATEST NAM SHOWS CAPE EXCEEDING 3000
J/KG WITH SHOWALTER INDEX AROUND -6 CENTERING ACROSS THE SOUTHWEST.
A FEW WRF MODELS WERE SHOWING SOME ISOLATED SHOWERS AND
THUNDERSTORMS ACROSS THE SOUTH HALF FOR THIS AFTERNOON WITH THE SPC
WRF SHOWING AN ISOLATED STRONG STORM IN THE SOUTHWEST. LATEST RUC/NAM SHOWS
SOME LOW LEVEL MOISTURE CONVERGENCE AT THE 1000-850 MB LEVEL FOR
THIS AFTERNOON...MAINLY ALONG AND WEST OF THE MS RIVER. THERE IS THE
POTENTIAL OF ONE OR MAYBE TWO STORMS ACROSS THE SOUTH HALF WITH SOME
POTENTIAL TO BE ON THE STRONG SIDE. WILL HOLD OFF ON MENTIONING THAT
IN THE HWO SINCE THE POTENTIAL FOR DEVELOPMENT IS ON THE SLIM SIDE.
SO HAVE PUT IN TEEN POPS ACROSS THE SOUTH HALF FOR THIS AFTERNOON.
WILL MONITOR FOR ANY DEVELOPMENT AND RECONSIDER THE HWO FOR LATER.
OTHERWISE HAVE ADJUSTED THE SKY GRIDS WITH THE LATEST 12Z NAM
GUIDANCE FOR A LITTLE MORE CLOUD COVER FOR PARTLY CLOUDY SKIES.
CURRENT HIGHS IN THE MID TO UPPER 80S LOOKS TO BE ON TRACK./17/

./PREVIOUS DISCUSSION...343 AM CDT SUN MAY 19 2013

.SHORT TERM...TONIGHT THROUGH MONDAY NIGHT...
SATELLITE AND OBSERVATIONS INDICATE STRATUS BUILDING INTO THE AREA
FROM THE SE THIS MORNING...WHILE SOME HIGH CLOUDS ALSO STREAM IN FROM
UPSTREAM CONVECTION OVER THE PLAINS. LATE SPRING HUMIDITY IS
PREVALENT WITH DEWPOINTS IN THE UPPER 60S TO NEAR 70.

EXPECT AREAS OF STRATUS TO CONTINUE TO OVERSPREAD REGION EARLY THIS
MORNING...AND THEN GRADUALLY GIVE WAY TO A MIX OF SUN...CUMULUS AND
HIGH CLOUDS THROUGH THE DAY. NORTHERN PERIPHERY OF AN UPPER
DISTURBANCE CURRENTLY ALONG UPPER TEXAS COAST PER WATER VAPOR IS
EXPECTED TO SKIRT ACROSS SOUTHERN PARTS OF FORECAST AREA THIS
AFTERNOON. CAPPING IS FORECAST BY THE MODELS TO HOLD TODAY...BUT
SOME CONCERN THAT COMBINATION OF DAYTIME HEATING AND SOME VERTICAL
MOTION ASSOCIATED WITH THE WAVE COULD ERODE CAPPING ENOUGH FOR AN
ISOLATED STORM OR TWO TO DEVELOP IN SOUTHERN AREAS. SUPPORT FOR THIS IN
THE MODELS IS PRETTY SLIM THOUGH...WITH ONLY SPC 4 KM WRF SHOWING ANY
DEVELOPMENT WITH OTHER NATIONAL/LOCAL HIGH RES AND GLOBAL MODELS ALL
DRY. FOR NOW WILL LEAVE ANY MENTION OF POPS OUT OF FORECAST...BUT
WILL NOTE THAT IF BY CHANCE ANYTHING WERE TO DEVELOP IT COULD BE
STRONG GIVEN MODEL FORECASTS OF STEEP LAPSE RATES AND MLCAPE VALUES
NEAR 3000 J/KG. GUIDANCE TEMPERATURES LOOK REASONABLE TODAY.

TONIGHT AND MON NIGHT SHOULD PRETTY MUCH BE A REPEAT OF THIS MORNING
WITH STRATUS INCREASING FROM THE SOUTH AND HIGH LEVEL CONVECTIVE
DEBRIS LIKELY INCREASING FROM THE W/NW. COMBINATION OF CLOUDS AND
DEWPOINTS IN 65 TO 70 DEGREE RANGE WOULD SEEM TO SUPPORT MINS A FEW
DEGREES ABOVE GFS MOS.

MONDAY SHOULD BE SIMILAR TO TODAY. MODELS SHOW AXIS OF HIGHEST PW AND
LOWEST CINH ACROSS WESTERN AREAS MON AFTERNOON. FOR NOW EXPECT THAT
BUILDING HEIGHTS AND CAPPING WILL WIN OUT EVEN HERE...AND WILL LEAVE
POPS OUT OF FORECAST. GUIDANCE TEMPERATURES ACCEPTED.  /08/

.LONG TERM...TUESDAY THROUGH SUNDAY...BY TUESDAY MORNING THE NEARLY
STACKED LOW WILL BE OVER THE CENTRAL PLAINS WITH A SHORTWAVE
ROUNDING ITS BASE OVER THE SOUTHERN PLAINS. SHORTWAVE RIDGING ALOFT
AND SURFACE RIDGING FROM THE EAST WILL STILL BE DOMINANT ACROSS OUR
CWA TUESDAY MORNING BUT HEIGHTS WILL BE FALLING AS THE UPPER TROUGH
DRAWS CLOSER. A RATHER WARM AND HUMID DAY IS EXPECTED AS
TEMPERATURES TOP OUT IN THE UPPER 80S. ALONG AND WEST OF THE
MISSISSIPPI RIVER PWS ARE EXPECTED TO EXCEED AN INCH AND A HALF WITH
LOWER 70 DEGREE SURFACE DEW POINTS. DAYTIME HEATING SHOULD LEAD TO
AFTERNOON AND EVENING CONVECTION IN OUR WESTERN ZONES WHILE
CONVECTION REMAINS MORE INHIBITED EAST. WITH MLCAPES ABOVE
2000J/KG...7.5C/KM MID LEVEL LAPSE RATES AND VERTICAL TOTALS
29-30...A FEW STRONG TO SEVERE HAIL PRODUCING STORMS WILL BE
POSSIBLE. TUESDAY NIGHT INTO WEDNESDAY THE LOW WILL LIFT NE AND
WEAKEN OVER THE UPPER MISSISSIPPI RIVER VALLEY. THE WEAKENING UPPER
LEVEL TROUGH WILL SWING ACROSS OUR CWA WEDNESDAY BUT MODELS HAVE
BACKED OFF ON ANY FROPA IN OUR CWA AS THE FRONT FIZZLES NORTH OF OUR
AREA. OVERALL...THERMODYNAMIC PARAMETERS LOOK LESS FAVORABLE FOR
SEVERE WEATHER WEDNESDAY INTO THURSDAY BUT WL STILL HAVE A WARM MOIST
AIRMASS IN PLACE WITH RATHER STEEP MID LEVEL LAPSE RATES SO A FEW
STRONG STORMS WILL BE HARD TO RULE OUT. THE UPPER TROUGH AXIS WILL BE
EAST OF OUR CWA THURSDAY BUT NORTHWEST FLOW ALOFT WILL CONTINUE OVER
OUR CWA THROUGH SATURDAY. ALTHOUGH MOST OF THE CONVECTION WILL SHOULD
SHOW A DISTINCT DIURNAL TREND...MODELS INDICATE DISTURBANCES ALOFT IN
THE NW FLOW MAY SET OFF SOME CONVECTION OVER NIGHT THURSDAY AND
FRIDAY NIGHTS. IN ADDITION...BOTH GFS AND ECMWF SHOW A SURFACE HIGH
DROPPING OVER THE GREAT LAKES REGION FRIDAY NIGHT THAT MAY PUSH A
WEAK BACKDOOR COLD FRONT INTO OUR CWA SATURDAY. RIDGING SURFACE AND
ALOFT IS EXPECTED TO BUILD OVER OUR REGION SUNDAY RESULTING IN DRY
WEATHER. /22/

&&

.AVIATION...REMAINING STRATUS/BR SHOULD GRADUALLY MIX OUT/BURN OFF
THROUGH THE REMAINDER OF THE MORNING...WITH A MIX OF CUMULUS AT
030-040 AND SOME CIRRUS EXPECTED IN THE AFTERNOON. WINDS WILL BE
FROM THE SOUTH AND GUSTY AT TIMES...PARTICULARLY IN THE DELTA AS
25-35 KT 925 MB FLOW MIXES OUT. THERE COULD BE AN ISOLATED STORM OR
TWO DEVELOPING IN THE AFTERNOON ALONG AND SOUTH OF I-20...BUT THE
CHANCES OF ANY IMPACT TO AVIATION OPERATIONS IN THE AERODROME IS
VERY MINIMAL. GENERALLY EXPECT A REPEAT AS FAR AS STRATUS
DEVELOPMENT FOR TONIGHT AS WE ARE SEEING THIS MORNING.  /BB/

&&

.PRELIMINARY POINT TEMPS/POPS...
JACKSON       89  70  89  70 /  16   4   8   9
MERIDIAN      88  68  90  66 /  16   4   7   8
VICKSBURG     89  70  90  70 /  16   5   9  10
HATTIESBURG   88  70  89  68 /  20   4   9   6
NATCHEZ       89  71  88  70 /  18   4  10   7
GREENVILLE    90  71  89  70 /  10   6   9  11
GREENWOOD     89  70  89  69 /  10   6   9  10

&&

.JAN WATCHES/WARNINGS/ADVISORIES...
MS...NONE.
LA...NONE.
AR...NONE.
&&

$$

17/BB/08/22