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000
FXUS64 KJAN 070259 AAA
AFDJAN

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JACKSON MS
859 PM CST FRI DEC 6 2013

.UPDATE...THE COLD FRONT FINALLY MADE ITS WAY THROUGH THE PINE BELT
EARLIER THIS EVENING. IN ADDITION MOST OF THE RAIN HAS PUSHED
EASTWARD OUT OF THE AREA...WITH RADAR NOW SHOWING ONLY LIGHT SHOWERS
BETWEEN COLLINS AND MERIDIAN/DE KALB AT THIS TIME. WITH MEASURABLE
PRECIP NOW WELL OUT OF THE FREEZING RAIN ADVISORY AREA...THE
ADVISORY HAS BEEN ALLOWED TO EXPIRE. THERE ARE STILL A FEW UPSTREAM
OBS INDICATING PATCHES OF VERY LIGHT FREEZING RAIN ACROSS
ARKANSAS...BUT THIS WOULD BE UNLIKELY TO CAUSE ANY ADDITIONAL
SIGNIFICANT IMPACT.

LOOKING AHEAD TO THE OVERNIGHT...FORECAST SOUNDINGS CONTINUE TO SHOW
A VERY SATURATED LAYER BETWEEN ABOUT 850 MB AND 975 MB (THE EXACT
LAYER VARIES DEPENDING ON MODEL OR LOCATION OF CHOICE) WHICH IS
INDICATIVE OF DRIZZLE POTENTIAL. HOWEVER LITTLE IF ANY LIFT IS
FORECAST DURING THE SAME TIME PERIOD. 295K ISENTROPIC ANALYSIS
DEPICTS FLOW PARALLEL TO THE ISOBARS...WHILE ANALYSIS AT HIGHER
LEVELS INDICATES SINKING AIR. 21Z SREF P-TYPE PROBABILITIES STILL
SHOW SOME POTENTIAL FOR FREEZING DRIZZLE...ALBEIT LOWER
PROBABILITIES THAN PREVIOUS RUNS.

GIVEN THIS INFORMATION...WILL MAINTAIN MENTION OF PATCHY LIGHT
FREEZING DRIZZLE GENERALLY ALONG AND NORTH OF THE NATCHEZ TRACE
DURING THE LATE OVERNIGHT PERIOD. BECAUSE PRECIP IS EXPECTED TO BE
VERY LIGHT IN NATURE AND CONTINUED NORTHERLY WINDS WILL HELP KEEP
SURFACES DRY...TRAVEL IMPACTS APPEAR TO BE UNLIKELY AT THIS TIME. WE
WILL CONTINUE TO MONITOR THE SITUATION THROUGH THE OVERNIGHT AND
MAKE ANY ADJUSTMENTS AS NECESSARY.

OTHERWISE...HOURLY TEMPS WERE UPDATED TO SHOW A QUICKER PROGRESSION
OF COLD AIR INTO THE SE PART OF THE CWA THAN PREVIOUSLY ANTICIPATED.
NO OTHER NOTABLE ADJUSTMENTS WILL BE MADE. /DL/

&&

.AVIATION...MAIN BATCH OF PRECIPITATION OVER EASTERN MISSISSIPPI AT
THE MOMENT RESULTING IN IFR CONDITIONS...SHOULD BE EAST OF THE AREA
BY 07/04Z WITH MVFR CEILINGS PREVAILING AT ALL TAF SITES THEREAFTER.
WINDS WILL INCREASE TO NEAR 15 KNOTS WITH PERIODIC GUSTS UP TO 25
KNOTS MAINLY AFTER 07/04Z./26/

&&

.DISCUSSION... /ISSUED AT 354 PM CST FRI DEC 6 2013/
SHORT TERM...
MUCH OF SATURDAY IS A LULL IN BETWEEN PRECIPITATION WAVES WITH
CLOUDY...BREEZY AND COLD CONDITIONS. TEMPS WILL LIKELY STRUGGLE TO
GET ABOVE FREEZING IN THE DELTA AS ARCTIC HIGH BUILDS IN AND
NORTHERLY WINDS CONTINUE OFF EXTENSIVE SNOW/ICE PACK THAT HAS BEEN
LAID DOWN TO OUR NW. WIND CHILL READINGS COULD BE NEAR ADVISORY
CRITERIA OF SINGLE DIGITS FOR A FEW HOURS SAT AM. GIVEN CURRENT
SMALL AREAL EXTENT AND BRIEF DURATION OF THOSE VALUES WILL NOT ISSUE
ADVISORY AT THIS POINT...BUT NEEDLESS TO SAY...IT IS GOING TO BE
VERY COLD. COULD BE A LITTLE LIGHT RAIN OR DRIZZLE AT TIMES...BUT
WILL KEEP POPS LOW. THINGS WILL BEGIN TO CHANGE AS FAR AS
PRECIPITATION POTENTIAL LATE IN THE DAY AND INTO SAT NIGHT AS LOW
LEVEL FLOW BACKS AND SUBSTANTIAL UPGLIDE ON 285-295K ISENTROPIC
SURFACES DEVELOPS OVER WESTERN AREAS. MODELS ARE ACTUALLY IN QUITE
GOOD AGREEMENT IN BREAKING OUT LIGHT PRECIPITATION OVER MUCH OF THE
NORTHWEST HALF OF THE AREA INTO SAT NIGHT...WITH THERMAL PROFILES
STRONGLY SUPPORTING FREEZING RAIN...ESPECIALLY NW OF A LINE FROM
RAYVILLE LA....TO GRENADA MS. SREF ALSO HAS HIGH PROBS FOR
MEASURABLE FZRA OVER OUR EXTREME NW AREAS...AND HAVE JUST WENT WITH
-FZRA AS PREDOMINANT PRECIP TYPE IN THIS AREA. BUFFER AREA FROM THERE
EAST TO JUST WEST OF THE TRACE SHOWING -RA OR -FZRA...JUST -RA
ELSEWHERE. WHILE CONFIDENCE IS RELATIVELY HIGH ON FZRA POTENTIAL IN
THE DELTA...AT THIS POINT AMOUNTS LOOK PRETTY LIGHT...AND PROBABILITY
OF REACHING WARNING CRITERIA APPEARS RATHER LOW. THIS IS ALSO
SUPPORTED BY WPC WINTER WEATHER PROBABILITIES WHICH HAVE NEAR 90 PCT
FOR .01" OF ICING...BUT ONLY ABOUT 5-10 PCT FOR .25". HENCE WILL NOT
GO WITH ANY KIND OF WATCH AT THIS POINT BUT RATHER HIGHLIGHT THE
POTENTIAL FOR TRAVEL ISSUES WITH HWO...GRAPHICAST AND STATEMENTS. IF
LATER FORECASTS SUPPORT HIGHER QPF...COULD STILL NEED A WATCH LATER
TONIGHT OR SAT.

DEPENDING ON EXACT EVOLUTION OF PRESSURE PATTERN AND EXTENT OF FLOW
COMING OFF THE SNOW/ICE TO OUR N...SUBFREEZING CONDITIONS COULD
LINGER INTO SUN AM ACROSS FAR NW. OTHERWISE...INCREASED LOW LEVEL WAA
SHOULD GET TEMPS ABOVE FREEZING EVERYWHERE BY MIDDAY. ATTENTION WILL
THEN TURN TO HEAVY RAIN POTENTIAL PRIMARILY ALONG SE OF NATCHEZ TRACE
LATE SUN INTO MON. 40-45 KT LOW LEVEL JET WILL REDEVELOP OVER SE
SECTIONS IN RIGHT ENTRANCE REGION OF INTENSE UPPER JET OVER LOWER
GREAT LAKES. THIS WILL FORCE STRONG ISENTROPIC ASCENT AND MOISTURE
TRANSPORT WITH NEAR 335K 850 MB THETA-E AND DECENT ELEVATED
INSTABILITY BEING PULLED UP INTO REGION. MODELS IN PRETTY GOOD
AGREEMENT OF AXIS OF HEAVY RAIN FROM MONTICELLO UP TO S OF
KGTR...WITH ECMWF SHOWING 2-3" AMOUNTS IN 24-36 HOURS LATE SUN INTO
MON. GIVEN GOOD MODEL AGREEMENT AND POTENTIAL FOR LOCALIZED HEAVIER
BANDS GIVEN TRAINING POTENTIAL AND HIGH MOISTURE...HAVE MENTIONED
HEAVY RAIN IN HWO AND INCLUDED IN GRIDS DURING THIS PERIOD.

TEMPERATURES ARE AN EXTREME CHALLENGE GIVEN STRONG BAROCLINICITY
ACROSS AREA WHICH WILL HANG IN THROUGH MONDAY. ESSENTIALLY HAVE
INITIALIZED GRIDS WITH ECMWF GUIDANCE AND MASSAGED AS NEEDED.  /AEG/

LONG TERM...
MONDAY NIGHT INTO TUESDAY MODELS IMPLY YET ANOTHER WAVE OF
PRECIPITATION FOR MON NIGHT INTO TUESDAY...WITH ECMWF A BIT HEAVIER
THAN THE GFS...BUT GFS PULLING MOISTURE BACK FARTHER NW TOWARD THE
DELTA. GIVEN PROXIMITY OF COLD AIR STILL HANGING AROUND...THIS COULD
MEAN YET ANOTHER CHANCE OF SOME WINTRY PRECIPITATION DEPENDING ON HOW
FAR PRECIPITATION MAKES IT NW...AND HOW MUCH COLD AIR DRAINS BACK
INTO AREA GIVEN EXTENSIVE SNOW/ICE PACK NOW TO OUR NW. FOR NOW WILL
NOT INCLUDE THIS IN GRIDS GIVEN LOW PROBABILITY...BUT SOMETHING TO
MONITOR.

MAY SEE A MIDWEEK LULL IN PRECIP CHANCES...BUT AT THIS POINT THIS
LOOKS TO BE SHORT LIVED. STRONG -PNA PATTERN LOOKS TO REMAIN IN
PLACE UFN WITH STRONG RIDGE OVER FL AND DEEP MEAN TROUGHING OVER
WESTERN US. THIS IS LIKELY TO KEEP OVERALL PATTERN ACTIVE INTO
LATTER PART OF NEXT WEEK. /AEG/

&&

.HYDROLOGY...
BAND OF HEAVIER RAIN AND EMBEDDED CONVECTION HAS NOW SHIFTED EAST OF
WHERE THE HEAVIEST RAIN FELL OVERNIGHT AND INTO TODAY OVER THE
DELTA...WHERE A FEW STREAKS OF 2 TO 4 INCHES OF RAIN OCCURRED. WILL
BE MONITORING EXPECTED LOCATION OF HEAVY AMOUNTS EARLY NEXT WEEK.
SOME PARTS OF NE AND EAST CENTRAL MS HAVE HIGHER RIVER FLOWS AND
MORE SATURATED CONDITIONS THAN THE AREAS THAT RECEIVED THE HEAVY RAIN
LAST 24 HOURS...SO DEPENDING ON AMOUNTS/LOCATIONS OF HEAVY RAIN WITH
THIS NEXT PRECIPITATION EVENT...COULD HAVE MORE IN THE WAY OF
PROBLEMS THAN WITH THE ONE ENDING THIS EVENING. /AEG/

&&

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

$$

DL/26/AEG