Area Forecast Discussion
Issued by NWS Jackson, MS

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FXUS64 KJAN 251625 AAA
AFDJAN

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JACKSON MS
1025 AM CST THU DEC 25 2014

.DISCUSSION...QUIET CHRISTMAS DAY ON TAP WITH LOTS OF SUNSHINE AND
SEASONAL CONDITIONS EXPECTED. MOST OF THE FORECAST IS ON TRACK...BUT
DID UP TEMPS A BIT TO FIT WITH THE SITUATION OF FULL SUN AND RETURN
FLOW DEVELOPING WHICH HAS YIELDED A TAD WARMER TEMPS THAN WHAT SOME
BLENDED GUIDANCE HAS SHOWN LATELY. /CME/

&&

.AVIATION...VFR CONDITIONS WILL PREVAIL THIS TAF PERIOD. WITH THE
RETURN FLOW BECOMING MORE ESTABLISHED LATE IN THE PERIOD...LOOK FOR
AN INCREASE IN LOW STRATUS AROUND OR AFTER SUNRISE FRIDAY. /SW/

&&

.PREV DISCUSSION... /ISSUED 351 AM CST THU DEC 25 2014/

DISCUSSION...CHRISTMAS DAY THROUGH FRIDAY NIGHT...MERRY CHRISTMAS
FROM THE MIDNIGHT SHIFT HERE AT NWS JACKSON! LOOK FOR A NICE
CHRISTMAS DAY ACROSS THE REGION AS HIGH PRESSURE AT THE SURFACE
BUILDS THROUGH THE LOWER MISSISSIPPI RIVER VALLEY. AFTER A CHILLY
START THIS MORNING...HIGHS WILL WARM INTO THE 50S UNDER SUNNY SKIES.
SOUTHERLY FLOW OVER THE AREA TODAY WILL ALLOW FOR SLIGHTLY WARMER
OVERNIGHT LOWS... RANGING FROM THE MID 30S TO AROUND 40 UNDER MOSTLY
CLEAR SKIES.

CONDITIONS WILL CONTINUE TO WARM FRIDAY AND FRIDAY NIGHT UNDER
PERSISTENT LOWER AND MID-LEVEL SOUTHERLY FLOW.  THE COMBINATION OF
AN APPROACHING MID/UPPER TROUGH FROM THE WEST AND INCREASING WARM
ADVECTION...WITH RESULT IN INCREASING CLOUDS AND RAIN CHANCES FROM
LATE FRIDAY AFTERNOON THROUGH FRIDAY NIGHT.  HIGHS FRIDAY WILL RANGE
FROM THE UPPER 50S TO MIDDLE 60S.  LOWS FRIDAY NIGHT WILL BE ON THE
MILD SIDE AS THEY ONLY RANGE FROM THE MID 40S TO UPPER 50S. /19/

SATURDAY THROUGH THURSDAY...AT THE ONSET OF THE PERIOD MID LEVEL
FLOW WILL HAVE ALREADY BEEN AMPLIFIED BY WAVE MOVING OUT OF THE PAC
NW INTO THE SOUTHERN ROCKIES. MOIST LOW LEVEL SOUTHERLY FLOW WILL BE
ONGOING AS SURFACE HIGH HAS SHIFTED TO THE EAST COAST. MEANWHILE...
DEEP SW FLOW ALOFT WILL HAVE ALREADY TAPPED INTO THE HIGH PW AIR
(VALUES AROUND 1.75) POISED OVER THE NW GULF OF MEXICO. ALL OF THIS
ACTING AS A PRELUDE TO ISENTROPIC RAINS BREAKING OUT OVER THE AREA.

RETREATING BAROCLINIC ZONE AHEAD OF SURFACE COLD FRONT OVER AR/LA
SATURDAY LOOKS TO ALLOW WARM SECTOR AND MID 60 DEWPOINTS TO SURGE AS
FAR NORTH AS THE HIGHWAY 84 CORRIDOR SATURDAY AFTERNOON INTO
SATURDAY NIGHT. WHILE NEAR MOIST ADIABATIC LAPSE RATES ARE NOT THAT
IMPRESSIVE...ML CAPES OF 300-500 J/KG ARE MORE THAN ADEQUATE FOR
THUNDER. GFS/ECMWF HAVING DIFFICULTIES FORECASTING 0-3KM SRH WITH
CONSIDERABLE DIFFERENCES BETWEEN THE TWO. HOWEVER...THEY ARE IN
AGREEMENT WITH DEEP LAYER SHEAR VALUES VALUES OF AROUND 50 KNOTS
OVER THE WARM SECTOR. WHILE THERE ARE POSITIVES AND NEGATIVES FOR
ORGANIZED CONVECTION...FEEL THERE IS ENOUGH OF A SIGNAL IN THE MODEL
DATA TO POSE A LIMITED THREAT OVER SOUTHERN SECTIONS OF THE CWA.

WHILE SURFACE COLD FRONT WILL HAVE MOVED OUT OF THE AREA BY SUNDAY
NIGHT...SW FLOW ALOFT WILL CONTINUE THE ANAFRONTAL ISENTROPIC RAIN
REGIME UNTIL MID LEVEL SHORT WAVE CAN PASS MONDAY AFTERNOON.
MEANWHILE...STRONG WAVE WILL BE DIGGING SOUTH THROUGH THE WESTERN US
AND CREATE A FAST PACED ZONAL FLOW OVER THE SOUTHERN CONUS. AS THE
MID LEVEL SYSTEM MOVES INTO THE FOUR CORNERS BY WEDNESDAY/
THURSDAY...ISENTROPIC RAINS LOOK TO BREAK OUT AGAIN OVER THE
REGION. /26/

&&


.PRELIMINARY POINT TEMPS/POPS...
JACKSON       57  37  61  53 /   0   0  13  43
MERIDIAN      56  33  60  48 /   0   0  13  35
VICKSBURG     58  37  62  54 /   0   0  14  45
HATTIESBURG   57  37  62  53 /   0   0  12  44
NATCHEZ       58  42  63  57 /   0   0  24  61
GREENVILLE    56  37  60  51 /   0   0  12  38
GREENWOOD     57  37  60  51 /   0   0  12  33

&&

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

$$

CME/SW/19/26/




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