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000
FXUS64 KJAN 081525 AAA
AFDJAN

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JACKSON MS
925 AM CST SUN DEC 8 2013

.UPDATE...
SW FLOW ALOFT IS MOVING DEEPER MOISTURE INTO THE REGION. MOISTURE IS
INCREASING DUE TO WAA/ISENTROPIC LIFT AT 295-305K AND UPPER JET
DYNAMICS OVER THE REGION. THE INCREASED LIFT AND PWATS INCREASING TO
1.3-1.4 INCHES IN REGIONAL 12Z SOUNDINGS WILL AID IN GOOD EFFICIENT
RAINFALL THIS AFTERNOON. ENDED THE FREEZING RAIN ADVISORY AS PRECIP
HAS MOVED OUT OF THE DELTA AND WILL NOT LIKELY MOVE BACK IN THIS
REGION UNTIL CLOSER TO 16-18Z...WHICH IS WHEN TEMPS WILL BE ABOVE
FREEZING. DECREASED POPS IN THE NW BUT LEFT CHANCE POPS UNTIL 17Z.
ALSO ADDED SLIGHT CHANCE THUNDER IN THE S AS SOME ELEVATED
INSTABILITY EXISTS. HIGHS TEMPS TODAY LOOK ON TRACK AND NO CHANGES
WERE MADE.  ONLY MADE SLIGHT CHANGES TO HOURLY TEMPS/DEWPOINTS
ACCORDING TO CURRENT TRENDS. REST OF THE FORECAST IS ON TRACK. /DC/

&&

.AVIATION...MOST TAF SITES WERE STILL REPORTING LIFR CEILINGS THIS
MORNING BUT MODEL SOUNDINGS SUGGEST THAT CEILINGS WILL SLOWLY RISE
TO BETWEEN 500-1000FT BY NOON AND CONTINUE THROUGH THIS EVENING SO
IFR CONDITIONS ARE STILL EXPECTED TO PREVAIL THROUGH TONIGHT. LOCAL
RADAR SHOWED A BAND OF RAIN ACROSS THE SE HALF OF THE AREA AT 15Z
AND ELEVATED INSTABILITY WILL LEAD TO A FEW TSTMS SE OF A LINE FROM
HEZ-JAN-MEI TODAY. THE RAIN WILL BECOME WIDESPREAD THIS AFTERNOON
LEADING TO VISIBILITY REDUCTIONS AT TIMES...BUT WORST RESTRICTIONS
WILL BE DUE TO THE LOW CEILINGS. A WEAK COLD FRONT WILL MOVE ACROSS
THE AREA TONIGHT AND BRING IMPROVED CONDITIONS TO GLH AND GWO TOWARD
12Z BUT LIGHT RAIN AND IFR/LIFR CONDITIONS WILL CONTINUE CNTRL AND
SOUTH. /22/

&&

.PREV DISCUSSION... /ISSUED 447 AM CST SUN DEC 8 2013/

..LIGHT ICING STILL POSSIBLE FOR PORTIONS OF THE ARKLAMISS DELTA
THIS MORNING...

SHORT TERM...PLUME OF HIGH MOISTURE (1.75 TO 2 INCH PRECIPITABLE
WATER VALUES) IS PUSHING NORTH THROUGH THE CENTRAL GULF OF MEXICO
THIS MORNING WHILE LIGHT PRECIP GRADUALLY INCREASES OVER THE BULK OF
THE FORECAST AREA. ISENTROPIC OVERRUNNING PROCESSES IN THE LOWER TO
MIDDLE LAYERS OF THE TROPOSPHERE WILL PRIMARILY DRIVE PRECIPITATION
DEVELOPMENT SINCE THE COLD WEDGE OF LOW LEVEL AIR EMANATING FROM ICE
AND SNOW FIELDS TO OUR NORTHWEST CONTINUES TO PUSH SOUTHEAST AND
UNDERCUT MUCH WARMER AIR SEVERAL THOUSAND FEET ABOVE THE GROUND. IT
DOES LOOK LIKE COLD ADVECTION IN THE BOUNDARY LAYER WILL BE DROPPING
OFF QUITE CONSIDERABLY TODAY...WHICH WILL ALLOW BIG INVERSIONS TO
RELAX A BIT AND SURFACE TEMPERATURES TO MODERATE OVER YESTERDAY`S
EXTREMELY CHILLY READINGS. THAT SAID...TEMPS OVER MANY AREAS (MAINLY
NORTHWEST OF THE NATCHEZ TRACE) EARLY THIS MORNING ARE RUNNING RIGHT
ABOUT AT FREEZING AND AT LEAST A FEW PATCHES OF LIGHT ICING ON
ELEVATED SURFACES IS A POSSIBILITY. BEST ICING POTENTIAL WILL LIKELY
REMAIN FURTHER INTO THE ARKLAMISS DELTA (WHERE A FREEZING RAIN
ADVISORY WILL BE IN EFFECT) UNTIL 8 TO 10 AM WHEN TEMPERATURES
SHOULD FINALLY GET ENTIRELY ABOVE FREEZING. BUT EVEN IN THE ADVISORY
ANY ICING SHOULD BE LESS THAN A TENTH OF AN INCH IN GENERAL AND THE
LARGEST IMPACTS WILL ON BE TRAVEL ACROSS BRIDGES AND ELEVATED
SURFACES.

BY MIDDAY TO AFTERNOON THE AFOREMENTIONED GULF MOISTURE PLUME WILL
BE CLOSE ENOUGH TO START RAMPING UP PRECIPITATION RATES ACROSS AT
LEAST THE SOUTHEASTERN TWO-THIRDS OF THE FORECAST AREA. MODELS
SUGGESTS PERHAPS ENOUGH INSTABILITY ALOFT TO FUEL SOME EMBEDDED
THUNDERSTORMS IN THE RAIN SHIELD ALONG AND SOUTHEAST OF THE NATCHEZ
TRACE AND ANY THUNDERSTORMS COULD SIGNIFICANTLY INCREASE RAINFALL
RATES...ALTHOUGH A WIDESPREAD FLOODING SITUATION IS NOT EXPECTED TO
DEVELOP WITH THIS ROUND OF RAINFALL.

EXPECTING THE WAVE COMING OUT OF THE TROUGH AXIS STILL TO OUR WEST
TO BE TRANSITIONING SLOWLY TO OUR EAST LATE TONIGHT THROUGH EARLY
MONDAY. THIS SHOULD GRADUALLY TAPER BACK RAINFALL FROM NORTHWEST TO
SOUTHEAST OVER THIS PERIOD...ALTHOUGH EVEN IN THE ARKLAMISS DELTA IT
MAY HARD TO GET RID OF DRIZZLE. AS SURFACE WINDS SWITCH BACK AROUND
TO THE NORTH THERE IS A NON-ZERO CHANCE THAT TEMPS COULD TREND BACK
COLD ENOUGH BY EARLY MONDAY MORNING IN PORTIONS OF THE ARKLAMISS
DELTA TO WORRY ABOUT LIGHT FREEZING RAIN AGAIN BRIEFLY. THIS IS
SOMETHING WE WILL MONITOR...BUT DOES NOT SEEM LIKE ENOUGH OF A
THREAT TO MENTION IN THE HWO AT THIS JUNCTURE. MEANWHILE...TEMPS
WILL BELOW NORMAL WITH THE CHILLIEST AIR AGAIN REMAINING CONFINED TO
THE ARKLAMISS DELTA.

THE PREVIOUSLY STAGNANT TROUGH AXIS TO OUR WEST FINALLY LOOKS TO BE
PHASING...WEAKENING...AND MOVING BY MONDAY NIGHT. THIS IS SOMEWHAT
TAKEN AS A WHOLE...BUT NOT SO GOOD FOR WEATHER MONDAY NIGHT WHEN
PRECIPITATION SHOULD SPILL BACK IN FROM THE SOUTHWEST. WILL HAVE TO
CONTINUE TO WATCH OUT FOR HEAVY RAINFALL THIS PERIOD IN SOUTHEASTERN
ZONES SINCE GROUNDS THERE SHOULD BE QUITE SATURATED AND CREEKS AND
STREAMS ALREADY HIGH. WILL ALSO HAVE TO WATCH FOR POTENTIAL OF
ANOTHER BRUSH WITH ICING IN THE ARKLAMISS DELTA AS TEMPERATURES HAVE
A CHANCE AT TRENDING JUST COLD ENOUGH LATE IN THE NIGHT BEFORE
PRECIP ENDS. LATEST THINKING IS THAT THIS POTENTIAL ALSO DOES NOT
LOOK TO BE A HUGE DEAL. /BB/

LONG TERM...TUESDAY THROUGH SUNDAY...THE UNSETTLED WEATHER PATTERN
THAT HAS CHARACTERIZED THE SHORT TERM FORECAST WILL TAKE A LITTLE
BREAK IN THE LONG TERM.

THE BEGINNING OF THE PERIOD WILL BE INTERESTING AS PRECIPITATION
WILL BE OCCURRING OVER PORTIONS OF THE CWA. MODELS STILL INDICATE
THAT THERE IS POTENTIAL FOR SOME OF THIS TO BE FREEZING RAIN IN THE
DELTA AND HAVE INCLUDED THIS IN THE GRIDS FOR A FEW HOURS IN THE
MORNING HERE. FOR THE REMAINDER OF THE CWA...THERE SHOULD NOT BE
FREEZING RAIN ISSUES AS TEMPERATURES WILL BE WARM ENOUGH AND
CONTINUE TO REMAIN ABOVE FREEZING.  THIS RAIN WILL CONTINUE TO MOVE
TO THE SOUTH AND EAST THROUGH THE DAY. THE NAM DRIES THE CWA OUT
VERY QUICKLY WHILE THE GFS AND ECMWF ARE A BIT SLOWER AND PUSH THE
RAIN OUT THROUGH THE AFTERNOON. AS THIS OCCURS...A 1037MB SFC HIGH
WILL PUSH INTO THE REGION FROM THE NORTH AND WILL INFLUENCE OUR
WEATHER FOR THE MIDDLE PORTIONS OF THE WEEK. THIS HIGH WILL TAKE
RESIDENCE OVER IOWA AND TRACK TO THE EAST THROUGH THURSDAY. THIS
WILL ALLOW MUCH DRIER AIR TO FILTER INTO THE REGION AS PW VALUES
DROP BELOW 1 INCH...AND EVEN 0.5 INCHES IN SOME NORTHERN LOCATIONS.
ALSO DURING THIS TIME...THE UPPER PATTERN BECOMES A BIT LESS
SOUTHWESTERLY AND UPPER RIDGING ACTUALLY OCCURS ABOVE US FOR A SHORT
TIME AT THE END OF THE WEEK.

THIS RIDGING WILL BE SHORT-LIVED AS ANOTHER SYSTEM IS DEVELOPING OUT
IN THE WESTERN CONUS. MOISTURE WILL RETURN TO THE REGION FRIDAY INTO
SATURDAY AS PW VALUES RETURN TO 1.3 TO 1.5 INCHES. THE SFC HIGH
MOVES OFF TO THE EAST AND ANOTHER STRONGER TROUGH DIGS ACROSS NEW
MEXICO AND TEXAS. RAIN BEGINS TO OVERSPREAD THE REGION AHEAD OF
THIS...AND A DEVELOPING SFC LOW. MODELS CONTINUE TO HAVE ISSUES WITH
REGARD TO THE TIMING OF THIS NEXT SYSTEM. THE GFS CONTINUES TO SHOW
THE TROUGH MOVING THROUGH ON SUNDAY BEHIND A SFC LOW THAT DEVELOPS
ALONG AND MOVES ACROSS THE GULF COAST. THE ECMWF CONTINUES TO BE
SLOWER GIVEN THE DEVELOPMENT OF A STRONGER TROUGH THAT DIGS FURTHER
SOUTH INTO NORTHERN MEXICO BEFORE EJECTING EASTWARD. THE SFC LOW IN
THE ECMWF CONTINUES TO PULL FURTHER NORTH THAN THE GFS...THIS TIME
MOVING ACROSS THE ARKLAMISS GENERALLY ALONG THE NATCHEZ TRACE
CORRIDOR. EITHER WAY...BOTH SOLUTIONS SHOULD BRING SOME RAIN TO THE
REGION.

TEMPERATURES CONTINUE TO BE A STRUGGLE THROUGH PORTIONS OF THE
FORECAST GIVEN CLOUDS AND RAIN. HOWEVER...IT LOOKS LIKE WE WILL
START THE PERIOD OFF COOL AND GRADUALLY WARM THROUGH THE WEEK AHEAD
OF THE WEEKEND SYSTEM. TEMPERATURES WILL BE NEAR OR SLIGHTLY BELOW
CLIMATE NORMALS. /28/

&&

.PRELIMINARY POINT TEMPS/POPS...
JACKSON       44  42  51  40 / 100  89  54  83
MERIDIAN      48  45  52  42 / 100  97  75  75
VICKSBURG     40  39  49  38 /  91  68  40  88
HATTIESBURG   51  50  58  45 /  84  80  58  56
NATCHEZ       41  41  51  38 /  94  77  49  84
GREENVILLE    37  35  44  32 /  77  53  22  67
GREENWOOD     40  37  47  33 /  92  69  32  72

&&

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

$$

DC/22/BB/28