Area Forecast Discussion
Issued by NWS Jackson, MS

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FXUS64 KJAN 021100
AFDJAN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
500 AM CST MON MAR 2 2015

.DISCUSSION...

TODAY THROUGH TUESDAY...

MOST OF THE ARKLAMISS IS OFF TO A FOGGY START THIS MORNING. A
PERSISTENT WEDGE OF SHALLOW COOL AIR OVER THE DELTA IS REMAINING
ANCHORED IN SPITE OF STRONG WARM ADVECTION ALOFT. THE PATTERN ISN`T
CONDUCIVE FOR MUCH EASTWARD PROGRESSION OF THE COOLER/MIXED AIR INTO
CENTRAL/EASTERN MS...AND THIS IS ALLOWING FOG WITH AREAS OF DENSE FOG
TO PERSIST. HAVE ISSUED A DENSE FOG ADVISORY ACCORDINGLY THROUGH MID
MORNING.

EXPECT SUFFICIENT MIXING/HEATING FOR THE FOG TO DIMINISH LATER THIS
MORNING...BUT A SHOWERY PATTERN WILL CONTINUE TODAY WITH PLENTY OF
LOW CLOUDS/DRIZZLE OUTSIDE OF SHOWER ACTIVITY. CONVECTIVE
INSTABILITY IS WEAK AND LARGE SCALE ASCENT IS BROAD AND
UNFOCUSED...BUT PRECIPITABLE WATER VALUES IN EXCESS OF 1.5 INCHES
WILL PROMOTE EFFICIENT RAINFALL AND LOCALLY HEAVY DOWNPOURS WILL
CONTINUE TO BE A POSSIBILITY.

AS WE GO INTO TONIGHT AND TUESDAY...A SFC-BASED WARM SECTOR WILL
ENVELOP THE ARKLAMISS AHEAD OF THE APPROACHING WRN CONUS TROUGH.
ANOTHER ROUND OF FOG IS EXPECTED LATER TONIGHT INTO EARLY TUESDAY.
EXPECT RAIN CHANCES TO DECREASE WHILE TEMPERATURES WARM UP WITH
HIGHS GETTING WELL INTO THE 70S TUESDAY. /EC/

LONG TERM (WEDNESDAY THROUGH SUNDAY)...FOCUS IN THE EXTENDED
CONTINUES TO BE ON A STRONG COLD FRONT BRINGING SHARPLY COLDER AIR
INTO THE REGION LATE WEDNESDAY INTO THURSDAY AND THE POTENTIAL FOR
CORRESPONDING WINTER WEATHER.

THE PERIOD WILL BEGIN WITH AN UPPER TROUGH EXTENDING FROM THE UPPER
PLAINS THROUGH THE SOUTHWEST CONUS...WITH A DOWNSTREAM AMPLIFYING
JET STREAK EXTENDING FROM THE LOWER PLAINS ACROSS THE GREAT LAKES
REGION. AT THE SURFACE...A STRONG COLD FRONT WILL BE SITUATED FROM
THE TN VALLEY WSWWARD THROUGH NORTH MS TO THE ARKLATEX ON WED
MORNING. THIS FRONT WILL SURGE SOUTHWARD THROUGH THE DAY...BRINGING
AN ABRUPT AIRMASS CHANGE ALONG WITH IT. THERE CONTINUE TO BE TIMING
INCONSISTENCIES AMONG AVAILABLE GUIDANCE...WITH THE GFS PRESENTING A
FASTER SOLUTION AND THE EURO/NAM/CMC/UKMET SLOWER ONES. ONCE AGAIN
WE FAVORED SOMETHING IN BETWEEN BUT A BIT CLOSER TO THE SLOWER
SOLUTIONS. DURING THE DAY THERE IS SOME POTENTIAL FOR THUNDERSTORMS
OVER THE SOUTHERN HALF OF THE AREA MAINLY DURING THE AFTERNOON GIVEN
PROGGED SBCAPES AS HIGH AS AROUND 1000 J/KG.

BEHIND THE FRONT...A DRASTIC TEMPERATURE DROP...ON THE ORDER OF
30-40 DEGREES IN SIX HOURS...WILL OCCUR BEGINNING WITH THE UPPER
DELTA IN THE LATE AFTERNOON...THEN ALONG THE NATCHEZ TRACE AFTER
DARK AND OVER THE SOUTHEAST DURING THE LATE NIGHT AND EARLY MORNING.
WITH THE STRONG UPPER JET MAX REMAINING NORTHWEST OF THE AREA...THIS
WILL CONTINUE TO PROMOTE LARGE SCALE LIFT AND POST FRONTAL PRECIP.
OF COURSE THE INITIAL SURGE OF COLD AIR WILL BE IN A SHALLOW NEAR
SURFACE LAYER...WITH A WARM NOSE OF ABOVE FREEZING TEMPS PERSISTING
IN THE 650-900 MB LAYER...WHICH WOULD TRANSLATE INTO FREEZING RAIN
OR SLEET POTENTIAL. NOW THAT RECENT SREF RUNS EXTEND INTO THIS TIME
FRAME...WE HAVE SEEN THE PAST FEW RUNS FAVOR A SUBSTANTIAL PROPORTION
OF SLEET ALONG WITH THE FREEZING RAIN OWING TO A RELATIVELY DEEP AND
COLD NEAR SURFACE SUBFREEZING LAYER. FORECAST SOUNDINGS SUPPORT THIS
IDEA AS WELL.

CURRENTLY WE BELIEVE THE MOST LIKELY ORIENTATION OF IMPACTS IN OUR
FORECAST AREA WILL BE MORE FROM SOUTHWEST TO NORTHEAST. SHALLOW COLD
AIRMASSES TEND TO SURGE MOST READILY ACROSS THE FLAT DELTA AREA...BUT
TAKE A BIT LONGER FARTHER EAST OUTSIDE OF THE DELTA. THIS WOULD ALLOW
FOR A LONGER PERIOD OF WINTRY PRECIPITATION GENERALLY NORTHWEST OF
THE NATCHEZ TRACE. UPDATED FORECAST WILL REFLECT A TRANSITION TO
WINTRY MIX IN THE DELTA BY LATE AFTERNOON...WITH POSSIBLE FROZEN
PRECIP DOWN TO ROUGHLY THE NATCHEZ TRACE BY 06Z AND DOWN TO A
BROOKHAVEN TO MERIDIAN CORRIDOR AROUND DAYBREAK. A TRANSITION TO SNOW
IS QUITE POSSIBLE IN THE DELTA BEFORE PRECIP ENDS THU MORNING AS THE
MID LEVEL WARM NOSE GRADUALLY ERODES. RIGHT NOW IT APPEARS THAT OVER
THE SOUTHEAST HALF OF THE AREA...ANY WINTRY PRECIP WOULD BE BRIEF
ENOUGH FOR IMPACTS TO BE UNLIKELY ESPECIALLY GIVEN THAT GROUND TEMPS
WILL BE RELATIVELY WARM. PRECIP IS EXPECTED TO BE OUT OF THE ENTIRE
AREA BY NOON THURSDAY. STRONG COLD ADVECTION WILL CONTINUE THROUGH
THE DAY...AND TEMPS WILL STRUGGLE TO GET OUT OF THE 30S ACROSS MOST
OF THE AREA...WITH SOME OF OUR NORTHERN COUNTIES STRUGGLING TO GET
ABOVE FREEZING.

NO MAJOR CHANGES ARE PLANNED FOR CURRENT OUTLOOK GRAPHICS. ASIDE
FROM CONTINUING TO MENTION WINTER WEATHER POTENTIAL IN THE HWO...WE
WILL ALSO POST A WINTER STORM OUTLOOK SPS FOR THE AREAS WHERE WE
HAVE THE HIGHEST CONFIDENCE IN IMPACTS FROM THIS SYSTEM...INCLUDING
MOST OF THE DELTA.

FOR THE REMAINDER OF THE WEEK...COLD HIGH PRESSURE WILL BUILD IN
OVER THE CENTRAL AND EASTERN CONUS...WHICH WILL LIMIT PRECIP CHANCES
THROUGH MOST OF THE PERIOD. THE EURO CONTINUES TO TEASE THE SOUTHERN
HALF OF THE AREA WITH PRECIP CHANCES HEADING INTO THE WEEKEND...
WHILE THE GFS REMAINS DRY. FOR NOW WE WILL CARRY LOWER END RAIN
CHANCES FROM FRIDAY NIGHT THROUGH SUNDAY. /DL/

&&

.AVIATION...

VERY POOR FLYING CONDITIONS CONTINUE EARLY THIS MORNING WITH
WIDESPREAD LIFR/IFR RESTRICTIONS DUE TO LOW STRATUS/FOG/DRIZZLE AND
SHOWER ACTIVITY. CONDITIONS WILL SLOWLY IMPROVE MID/LATE MORNING AS
CIGS LIFT SOME...BUT EXPECT FOG TO RETURN TONIGHT. /EC/

&&

.PRELIMINARY POINT TEMPS/POPS...
JACKSON       58  54  72  63 /  80  45  42  43
MERIDIAN      61  53  76  62 /  80  52  35  37
VICKSBURG     52  49  74  63 /  80  40  42  47
HATTIESBURG   70  59  76  63 /  80  34  28  26
NATCHEZ       56  53  75  64 /  80  38  42  34
GREENVILLE    45  43  68  56 /  80  41  45  74
GREENWOOD     49  47  70  60 /  80  48  45  65

&&

.JAN WATCHES/WARNINGS/ADVISORIES...
MS...DENSE FOG ADVISORY UNTIL 10 AM CST THIS MORNING FOR MSZ026>033-
     036>039-042>066-072>074.

LA...DENSE FOG ADVISORY UNTIL 10 AM CST THIS MORNING FOR LAZ016-
     023>026.

AR...NONE.

&&

$$

EC/DL




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