Area Forecast Discussion
Issued by NWS Jackson, MS

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000
FXUS64 KJAN 210937
AFDJAN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
437 AM CDT TUE APR 21 2015

...IMPACT FROM A COMPLEX OF THUNDERSTORMS POSSIBLE LATE WEDNESDAY...

.SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT...EARLY MORNING WATER
VAPOR IMAGERY/RAP ANALYSIS SHOWED THE CIRCULATION AROUND A CLOSED
LOW SPINNING OVER THE UPPER MISSISSIPPI VALLEY AND WESTERN GREAT
LAKES REGION. A SHORTWAVE ROUNDING THE BASE OF THE ASSOCIATED LARGE
UPPER LEVEL TROUGH HELP SET OFF A FEW THUNDERSTORMS EARLIER THIS
MORNING OVER THE THE TEXAS PANHANDLE BUT THESE HAVE SINCE
DISSIPATED. THIS SHORTWAVE WILL MOVE OVER OUR CWA TODAY BUT ONLY
PRODUCE A FEW MID AND HIGH LEVEL CLOUDS. DRY WEATHER SHOULD CONTINUE
TODAY AND LAST THROUGH MUCH OF WEDNESDAY MORNING. EARLY MORNING
SURFACE ANALYSIS HAD A 1018MB HIGH CENTERED OVER THE ARKLATEX THAT
WILL BECOME CENTERED OVER OUR CWA THIS MORNING AND CONTINUE SHIFTING
EAST THROUGH WEDNESDAY. THE 00Z TUE JAN SOUNDING HAD A PW BELOW A
HALF INCH AND SURFACE DEW POINTS ARE RUNNING IN THE 40S. ANOTHER
SLIGHTLY COOLER THAN NORMAL AND LOW RELATIVE HUMIDITY DAY IS ON TAP
AS SITES TOP OUT IN THE MID TO UPPER 70S. THE SURFACE HIGH WILL BE
EAST OF OUR CWA TONIGHT LENDING TO A LIGHT RETURN FLOW OVER OUR
REGION. THIS WILL HELP PROVIDE WARMER MORNING LOWS BUT ANOTHER NIGHT
OF COOLER THAN NORMAL TEMPERATURES IS EXPECTED.

WEDNESDAY A SHORTWAVE EJECTING OUT OF THE BASE OF A SECOND CLOSED
LOW SPINNING OVER SOUTHERN CALIFORNIA/ARIZONA WILL HELP DEEPEN A
SURFACE LOW OVER THE SOUTHERN PLAINS THAT WILL STRENGTHEN THE WAA
OVER OUR CWA BY AFTERNOON. THIS COMBINED WITH DAYTIME HEATING WILL
LEAD TO A FEW SHOWERS AND THUNDERSTORMS OVER OUR CWA EARLY IN THE
AFTERNOON. MORE VIGOROUS CONVECTION IS EXPECTED IN VICINITY OF THE
RED RIVER VALLEY THAT MODELS STILL SUGGEST COULD FORM INTO A COMPLEX
OF STORMS AS IT TRACKS EAST SOUTHEAST TOWARD OUR CWA. HIRES MODELS
MOVE THIS ACTIVITY INTO OUR WESTERN ZONES BY LATE AFTERNOON WITH THE
ACTIVITY SPREADING ACROSS THE REMAINDER OF OUR CWA DURING THE
EVENING. SUCH A COMPLEX OF STORMS COULD BRING DAMAGING WINDS AS WELL
AS HAIL AND LOCALLY HEAVY RAINFALL. THE AREA AT GREATEST RISK OF
THESE CONDITIONS REMAINS OUR SOUTHWEST ZONES. /22/

.LONG TERM...THURSDAY THROUGH MONDAY...A STRONG SUBTROPICAL JET WILL
BE ANCHORED ACROSS THE DEEP SOUTH AT THE BEGINNING OF THE PERIOD...
BEGINNING TO RIDGE ACROSS THE LOWER MS VALLEY LATER THURSDAY INTO
FRIDAY. AT THE SURFACE...A FRONT WILL EXTEND GENERALLY FROM WNW TO
ESE BISECTING THE CWA. ISOLATED TO SCATTERED CONVECTION WILL BE
POSSIBLE THURSDAY AIDED BY THE FRONT AND PASSING UPPER DISTURBANCES.
IN THE WARM SECTOR ACROSS THE SOUTHWEST PORTION OF THE AREA THERE IS
POTENTIAL FOR MORE VIGOROUS CONVECTION SHOULD THERE BE SUFFICIENT
INSOLATION DURING THE DAY...BUT THERE REMAINS QUITE A BIT OF
UNCERTAINTY DUE TO THE POTENTIAL FOR LATE WED OVERNIGHT/EARLY THU
MORNING STORMS DISRUPTING THE AIRMASS.

HEADING INTO FRIDAY...GUIDANCE SHOWS A MORE ROBUST SIGNAL FOR
ORGANIZED CONVECTION AS UPPER TROUGHING BUILDS OVER THE SOUTHWESTERN
CONUS AND A STRONG SHORTWAVE CROSSES THE PLAINS TOWARD THE MID MS
VALLEY. LARGE SCALE FORCING FOR ASCENT WILL EXIST IN THE RIGHT REAR
QUADRANT OF AN UPPER JET MAX EXTENDING FROM THE OHIO VALLEY TOWARD
THE ATLANTIC COAST...AND LOW AND MID LEVEL FORCING WILL INCREASE
OVER THE AREA THROUGH FRIDAY NIGHT. AT THE SURFACE...QUALITY
MOISTURE WILL ADVECT INTO THE WARM SECTOR THROUGH THE DAY WITH
GUIDANCE DEPICTING 70+ DEWPOINTS IN THIS AREA. AT THIS POINT...
CONVECTION WOULD APPEAR TO BE MOST LIKELY FROM FRIDAY AFTERNOON INTO
THE NIGHT. THOUGH THERE COULD ALSO BE REDEVELOPMENT OVER S/E PARTS
OF THE AREA SATURDAY BEFORE THE FRONT FINALLY PUSHES THROUGH BY
EVENING. WHILE IT IS STILL TOO SOON TO NARROW DOWN SPECIFICS...FEEL
THIS IS ENOUGH TO WARRANT INTRODUCING A LIMITED SEVERE TSTORM THREAT
TO HWO/GRAPHICS TO GENERALLY THE SOUTHWEST HALF OF THE AREA...WHERE
THERE IS GREATER CONFIDENCE IN BETTER INSTABILITY/LAPSE RATES...FOR
FRIDAY/FRIDAY NIGHT.

IT STILL APPEARS THAT WE WILL SEE A BREAK IN RAIN CHANCES LASTING
FROM LATER SATURDAY INTO SUNDAY AS A SURFACE RIDGE BUILDS IN.
LOOKING AHEAD TO EARLY NEXT WEEK...THERE IS MUCH POORER MODEL
AGREEMENT. WHILE THE GFS REMAINS GENERALLY DRIER...THE EURO SHOWS
RAIN RETURNING BY MONDAY. /DL/

&&

.AVIATION...ONLY A FEW HIGH CLOUDS WERE NOTED ON SATELLITE IMAGERY
STREAMING OVER SOUTHERN MS AS VFR CONDITIONS WERE BEING OBSERVED AT
ALL TAF SITES OVERNIGHT. VFR CONDITIONS ARE EXPECTED TO PREVAIL
THROUGH THIS EVENING AS HIGH PRESSURE SHIFTS EAST ACROSS THE AREA
TODAY. LIGHT AND VARIABLE WINDS WILL RESULT. MODELS SUGGEST SOME
MVFR/IFR VSBY RESTRICTIONS IN THE SOUTH WEDNESDAY MORNING. /22/

&&

.PRELIMINARY POINT TEMPS/POPS...
JACKSON       76  54  82  62 /   3   4  18  38
MERIDIAN      76  50  82  61 /   3   3  13  37
VICKSBURG     77  54  82  63 /   4   4  29  59
HATTIESBURG   79  54  82  65 /   3   2  12  37
NATCHEZ       76  56  82  65 /   3   4  27  61
GREENVILLE    75  54  78  61 /   6   5  37  61
GREENWOOD     75  52  79  59 /   5   5  28  46

&&

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

$$

22/DL/22



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