Area Forecast Discussion Wed, 22 May 2013 20:25:09 +0600

FXUS64 KJAN 230225 AAA
AFDJAN

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JACKSON MS
925 PM CDT WED MAY 22 2013

.UPDATE...
REGIONAL 00Z SOUNDING ANALYSIS INDICATES MID/UPPER LEVELS DRYING TO 
THE WEST AND CLOUDS HAVE BEGUN TO CLEAR ACROSS MOST OF THE REGION. 
SLIGHTLY MODIFIED SKY COVER GRIDS TO ACCOUNT FOR FASTER CLEARING OF 
CLOUDS. REMOVED POPS FOR TONIGHT AS ISOLATED ACTIVITY HAS WANED AND 
MOVED OUT OF THE REGION. TEMPERATURES WERE SLIGHTLY COOLER AND 
ADJUSTED HOURLY TEMP/DEWPOINT GRIDS CLOSER TO LAV. MID/UPPER LEVEL 
DRYING...LIGHT SURFACE WINDS...DECENT RADIATIONAL COOLING AND RECENT 
RAINFALL WILL AID IN SOME AREAS OF PATCHY DENSE FOG. THE MOST LIKELY 
AREA FOR SOME PATCHY DENSE FOG WILL EXIST MAINLY ALONG AND SOUTHEAST 
OF THE NATCHEZ TRACE CORRIDOR THEN LIFT AROUND 14-15Z. WILL HOLD OFF 
ON DENSE FOG ADVISORY UNTIL MORE CERTAINTY ON FOG ACTUALLY DEVELOPING
AND WHERE IT WOULD DEVELOP. REST OF THE FORECAST IS ON TRACK.

THURSDAY AFTERNOON TO EVENING

THE REGION WILL STAY SITUATED UNDER NORTHWESTERLY FLOW ALOFT AND A 
WEAK S/WV MAY AID IN SOME POSSIBLE THUNDERSTORM ACTIVITY TOMORROW IN 
VICINITY OF THE LINGERING FRONTAL BOUNDARY. STEEP LAPSE RATES AND 
VERTICAL TOTALS APPROACHING 28-30 COULD SUPPORT SOME ROBUST 
THUNDERSTORM DEVELOPMENT. HOWEVER...THERE IS STILL SOME UNCERTAINTY 
IF ANYTHING WILL DEVELOP. WILL WAIT FOR NEW GUIDANCE TO SEE IF IT 
RESOLVES ANY DEVELOPMENT. /DC/

&&

.AVIATION...QUIET EVENING ACROSS THE REGION WITH VFR CONDITIONS 
PREVAILING. THINKING IS THAT SOME OF THE CWA WILL SEE FOG 
DEVELOPMENT (MAINLY S/SE AREAS) AND WILL HAVE CONDITIONS DROPPING TO 
MVFR THEN IFR AT HBG/MEI. CONDITIONS SHOULD IMPROVE QUICKLY AND WILL 
TREND TAFS TO VFR AROUND 14Z. /CME/

&&

.PREV DISCUSSION... /ISSUED 409 PM CDT WED MAY 22 2013/ 

TONIGHT THROUGH THURSDAY NIGHT...

DESTABILIZATION WAS INSUFFICIENT FOR GETTING SUBSTANTIAL
SHOWER/THUNDERSTORM ACTIVITY THIS AFTERNOON IN THE WAKE OF THE
MORNING CONVECIVE SYSTEM. RAIN CHANCES WILL CONTINUE TO DECREASE
TONIGHT INTO THURSDAY AS HEIGHTS RISE AND DRYING TAKES PLACE IN THE
MID/UPPER LEVELS. THE PRIMARY CONCERN FOR LATE TONIGHT INTO EARLY
THURSDAY MORNING WILL BE FOG DEVELOPMENT AS SKIES CLEAR OUT IN THE
PRESENCE OF A SHALLOW MOIST BOUNDARY LAYER WITH LIGHT SURFACE WINDS.
WE HAVE INCLUDED THE POSSIBILITY FOR PATCHY AREAS OF DENSE FOG IN THE
HWO/GRAPHICS FOR NOW. 

THERE ARE INDICATIONS IN THE GFS THAT LOW-LEVEL MOISTURE CONVERGENCE
WILL INCREASE ALONG THE LINGERING FRONTAL BOUNDARY LATE THURSDAY
AFTERNOON INTO THURSDAY EVENING. MID LEVEL LAPSE RATES WILL BE STEEP
IN NORTHWEST FLOW ALOFT...BUT VERY WEAK FORCING AND QUESTIONABLE MID-
UPPER LEVEL MOISTURE SHOULD MAKE CONVECTIVE PRECIPITATION DIFFICULT
TO GENERATE. HAVE INTRODUCED SLIGHT THUNDERSTORM CHANCES FOR NOW
GIVEN EXPLICIT TSTM DEVELOPMENT IN SOME OF THE WRF GUIDANCE. /EC/

FRIDAY THROUGH WEDNESDAY...THE AIR MASS WILL DRY AND COOL SOME FRIDAY
AS HIGH PRESSURE BECOMES MORE ESTABLISHED. UPPER RIDGING WILL REMAIN
IN PLACE SATURDAY WITH WEAK TROUGHING FORECAST TO FLATTEN RIDGING FOR
THE AREA SUNDAY. LOW LEVEL SLY FLOW WILL BE IN PLACE AGAIN BY SUNDAY
BUT THE AIR MASS SHOULD REMAIN RELATIVELY DRY. THE EURO BRINGS
SLIGHTLY STRONGER UPPER TROUGHING TO THE REGION SUNDAY WITH
INCREASING MOISTURE FROM THE NW. ITS ALSO MORE INDICATIVE OF AT LEAST
ISOLATED SHOWERS FOR MONDAY...PRIMARILY IN THE NORTH...DEVELOPING
SURFACE TROUGHING INTO NRN AR AND TN WHILE THE GFS KEEPS THESE
FEATURES FARTHER N. THE DRIER GFS SOLUTION WILL BE FOLLOWED FOR NOW
IN THE LONGER RANGE BUT RAIN CHANCES WILL BE ADDED IF IT BEGINS TO
TREND TOWARD THE SLIGHTLY MORE ACTIVE LOOKING EURO.

COLD AIR ADVECTION WILL BE ONGOING EARLY FRIDAY IN THE WAKE OF THE 
SECONDARY BOUNDARY. WILL FOLLOW UNSEASONABLY COOL MEX MOS HIGHS FOR 
FRIDAY AFTERNOON...CUTTING MOS HIGHS SLIGHTLY IN THE FAR SOUTH TO 
THE MID 80S CONSIDERING THE COOLER LOW LEVEL TEMPS ADVERTISED BY THE 
MODELS/FORECAST SOUNDINGS. SIGNIFICANTLY COOLER LOWS ARE FORECAST BY 
MEX MOS FOR SATURDAY MORNING...INCLUDING READINGS IN THE MID 40S 
OVER MUCH OF THE AREA N OF I-20 AND E OF I-55. HAVE ADJUSTED THESE 
SLIGHTLY WARMER MORE IN LINE WITH THE GFS ENSEMBLE AND EURO BUT KEPT 
TEMPS IN THE UPPER 40S/NEAR 50 FOR MANY OF THOSE AREAS FOR NOW. A 
GRADUAL WARMING TREND BEGINS SATURDAY AFTERNOON WITH A RETURN TO 
WARMER TEMPS AND MORE HUMID CONDITIONS FOR SUNDAY INTO EARLY NEXT 
WEEK IN LOW LEVEL SLY FLOW. /03/

&&

.PRELIMINARY POINT TEMPS/POPS...
JACKSON       65  90  64  83 /   0  14  16  10 
MERIDIAN      61  91  61  84 /   4  12  13   4 
VICKSBURG     63  90  64  84 /   0  15  16  12 
HATTIESBURG   64  89  66  88 /   5  14  15   2 
NATCHEZ       66  89  65  83 /   0  17  18   7 
GREENVILLE    63  89  63  77 /   0  15  16  12 
GREENWOOD     62  88  61  78 /   0  13  14   6 

&&

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

$$

DC/CME/EC/03
NWS JAN Area Forecast Discussion

Area Forecast Discussion Wed, 22 May 2013 20:25:09 +0600
