FXUS64 KJAN 281016
AFDJAN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
416 AM CST SAT NOV 28 2009
.SHORT TERM...(TODAY THROUGH SUNDAY NIGHT)...
THE PRIMARY WEATHER CONCERN WILL BE OUR CHANCE OF SHOWERS WITH A COLD
FRONT FOR THE SUNDAY-SUNDAY NIGHT TIME RANGE. ALSO IF ANY INSTABILITY
WILL BE WITH THIS SYSTEM FOR ANY KIND OF CONVECTION.
LATEST SATELLITE IMAGERY SHOWS AN UPPER RIDGE EXTENDING OVER THE
ARKLAMISS REGION WITH MID TO MOSTLY HIGH LEVEL CLOUDS. A SHORT WAVE
WAS APPROACHING THE REGION FROM THE SOUTHERN PLAINS. WE WERE UNDER
THE INFLUENCE OF WESTERLY FLOW ALOFT. SURFACE HIGH PRESSURE WAS
CENTERED OVER THE SOUTHEAST LOUISIANA GULF COAST.
FOR TODAY THROUGH TONIGHT...SURFACE HIGH PRESSURE WILL MOVE EAST OF
THE REGION DURING THE PERIOD AS MID TO MOSTLY HIGH LEVEL CLOUDS
CONTINUE TO MOVE ACROSS THE REGION. WESTERLY FLOW ALOFT WILL
GRADUALLY BECOME SOUTHWESTERLY BY THIS AFTERNOON AS A WEAK SOUTHERN
STREAM SHORTWAVE CROSSES THE REGION. THIS WILL HELP TO KEEP THE MID
TO HIGH LEVEL CLOUDS AROUND. LOOKING AT TEMPS FOR THE DRY PERIOD. FOR
TODAY WITH RETURN FLOW AROUND AND 850 TEMPS PUSHING TOWARD
11C...READINGS SHOULD REBOUND INTO THE LOWER TO UPPER 60S. THIS IS
SUPPORTED BY AFTERNOON READINGS IN THE MID TO UPPER 60S ACROSS THE
ARKLATEX REGION YESTERDAY AFTERNOON...WHICH WILL COME TO OUR REGION
ON TODAY. WENT WITH CURRENT FORECAST...AS MAV...MOS AND ESPECIALLY
NAM GUIDANCE LOOKED TOO COOL. GRANTED WE WILL HAVE SOME HIGH
CLOUDS...BUT BELIEVE THAT THERE WILL BE ENOUGH SUNSHINE TO PUSH TEMPS
WELL INTO THE 60S. FOR SATURDAY NIGHT EXPECT CLOUDS TO GRADUALLY
INCREASE IN COVERAGE AHEAD OF THE APPROACHING SYSTEM COMING FROM THE
PLAINS. WE SHOULD BE ABLE TO REACH FROM NEAR 40 IN THE EAST WITH 40S
TO AROUND 50 ELSEWHERE. WENT CLOSE TO MAV GUIDANCE. MOS AND NAM
GUIDANCE LOOKED A LITTLE COOL WITH THE INCREASE IN CLOUDS OVERNIGHT.
FOR SUNDAY INTO SUNDAY NIGHT. THE SREF...EUROPEAN...NAM...GFS AND
UKMET HAVE REMAINED CONSISTENT IN SLOWING THE RAIN TIMING FOR
MAINLY SUNDAY NIGHT WITH THE FRONTAL SYSTEM AND ASSOCIATED SHORT
WAVE. MODELS STILL SHOW THAT THE INSTABILITY WITH THIS SYSTEM WILL
BE QUITE WEAK. IN THE ISENTROPIC DEPARTMENT THERE WILL BE SOME
PRETTY GOOD ISENTROPIC LIFT...SOME ISENTROPIC NET OMEGA...SOME GOOD
GENERAL INCREASING OMEGA AHEAD AND BEHIND THE FRONT. PRECIPITABLE
WATER WILL INCREASE TO APPROACHING 1.5 INCHES. THIS SHOULD PROVIDE
SOME PRETTY GOOD RAIN COVERAGE FOR SUNDAY NIGHT. MOS POPS LOOKED A
LITTLE HIGH FOR SUNDAY...SO CUT BACK ON POPS FOR SUNDAY. WENT CLOSE
TO MOS HIGH POPS FOR SUNDAY NIGHT. AS FAR AS TEMPS ARE CONCERN 850
TEMPS WILL BE IN THE 9-10C RANGE. SO TEMPS WILL BE IN MIDDLE 60S TO
LOWER 70S. WENT CLOSE TO MOS GUIDANCE. MAV GUIDANCE LOOKED A LITTLE
COOL. FOR SUNDAY NIGHT WITH THE FRONT COMING THROUGH TEMPS WILL
RANGE FROM THE UPPER 40 TO THE MIDDLE 50S. WENT CLOSE TO MAV
GUIDANCE. MOS AND NAM GUIDANCE LOOKED A LITTLE COOL. /17/
.LONG TERM...(MONDAY THROUGH SATURDAY)...
COLD FRONT TRAVERSING THE REGION MONDAY WILL CONTINUE TO SLIDE TO
THE SOUTHEAST THROUGH THE MORNING HOURS AND EXIT THE CWA IN THE
AFTERNOON. NORTHERLY WINDS WILL INCREASE BEHIND THE FRONT AND WILL
LIKELY NEED A LAKE WIND ADVISORY FOR AREA LAKES AFTER FROPA. MEX POPS
LOOKED GOOD MON KEEPING LIKELY WORDING FOR MOST OF THE AREA AND A
CHANCE OF RAIN FOR THE NORTHWESTERN TIER COUNTIES. LOW LEVEL
WARM/MOIST ADVECTION AHEAD OF THE FRONT STRUGGLES TO DEVELOP ANY
SIGNIFICANT INSTABILITY DUE TO THE DRY BL CONDITIONS PRESENT ALONG
THE GULF COAST...AS WELL AS OVER THE NORTHERN GULF AND WILL MAINTAIN
ZERO THUNDER CHANCES IN THE FORECAST THROUGH MONDAY.
FROM HERE THE FORECAST CONCERN IS CENTERED ON SFC LOW PRESSURE IN
THE WESTERN GULF DEVELOPING MONDAY NIGHT ALONG THE FRONTAL
BOUNDARY...AHEAD OF AN APPROACHING SRN STREAM S/WV...AND THE
ASSOCIATED HEAVY RAIN AND THUNDER CHANCES FOR THE ARKLAMISS THROUGH
WEDNESDAY. GFS/ECMWF/GEFS ARE IN DECENT AGREEMENT WITH THE
DEVELOPMENT OF THE LOW LATE MONDAY OUT OVER THE WESTERN GULF. FROM
HERE THE GUIDANCE DIFFERS A BIT AS THE GFS/00Z OUTRUNS ITS ENSEMBLE
MEAN AS WELL AS THE ECMWF/00Z WITH THE PROGRESSION OF THIS SYSTEM.
GFS ADVANCES THE UPPER LOW INTO CENTRAL LA BY 12Z WED...WITH THE
ECMWF KEEPING THE UPPER LOW BACK OVER THE FORT WORTH AREA 12Z WED.
THE GEFS SHOWS MORE SUPPORT FOR THE ECMWF SOLUTION MAKING FOR LOWER
CONFIDENCE IN THE GFS. FOR NOW...WILL GRADUALLY REINTRODUCE POPS
MONDAY NIGHT BUT NOT QUITE AS FAST AS GFS SUGGESTS BASED ON THE
PREFERRED SLOWER SOLUTION. RAIN CHANCES WILL CONTINUE INCREASING FROM
SOUTH TO NORTH THROUGH THE DAY TUESDAY AS THE SFC LOW TRACKS TOWARD
THE GULF COAST. HAVE INTRODUCED SOME THUNDER CHANCES STARTING OVER
WESTERN AREAS TUESDAY NIGHT AS WARM/MOIST AIR IS LIFTED OVER THE BL
AHEAD OF THE LOW(MODELS INDICATE A SWATH OF 200-400J/KG MUCAPE
SLIDING ACROSS NORTHERN AREAS)...COMBINED WITH APPROACHING DEEP LAYER
LIFT/STRENGTHENING JET SUPPORT IN ADVANCE OF THE UPPER S/WV. WILL
KEEP THUNDER CHANCES ACROSS NORTHERN AND EVENTUALLY NORTHEASTERN
ZONES THROUGH THE MORNING HOURS WEDNESDAY BEFORE COOL/DRY ADVECTION
DEVELOPS ACROSS THE ARKLAMISS IN WAKE OF THE LOW THAT HAS NOW PASSED
EAST OF THE AREA. ONE ITEM OF NOTE IS THE DISCREPANCY BETWEEN THE
GFS/ECMWF WITH REGARDS TO RAIN TOTALS WITH THIS SYSTEM. THE MORE
PROGRESSIVE GFS POSITIONS A SWATH OF 4 TO 6IN OF RAIN WELL EAST OF
OUR CWA WHILE THE ECMWF/00Z SHOWS A SWATH OF 4 TO 5IN FALLING OVER
FAR SOUTHEASTERN AREAS OF THE ARKLAMISS BY 12Z WED. CONSIDERING THE
UNCERTAINTY IN THE TRACK OF THE LOW AT THIS POINT WILL FORGO MENTION
OF HEAVY RAIN IN THE HWO. THIS WILL BE MONITORED AS THE SITUATION
EVOLVES.
RAIN CHANCES WILL TAPER OFF WEDNESDAY AFTERNOON INTO THE EVENING AS
THE LOW MOVES EAST BUT DID NOT DECREASE RAIN CHANCES QUITE AS FAST
AS THE GFS SUGGESTS WITH SLIGHT CHANCE POPS CARRIED OVER
NORTHEASTERN ZONES INTO WEDNESDAY EVENING. FROM HERE MODELS
GENERALLY AGREE COLD HIGH PRESSURE WILL SETTLE OVER THE REGION FOR
THE REMAINDER OF THE WEEK KEEPING RAIN CHANCES OUT...AND BELOW
NORMAL TEMPS IN THE FORECAST THROUGH SATURDAY.
MEX TEMPS LOOKED REASONABLE THROUGH THE PERIOD ALTHOUGH SOME
ADJUSTMENTS TOWARD MEN GUID WERE MADE LATE IN THE WEEK. /BK/
&&
.AVIATION...VFR CONDITIONS WILL CONTINUE THROUGH THE PERIOD AS HIGH
PRESSURE PREVAILS OVER THE AREA WITH HIGH THIN CLOUDS AROUND FOR
TODAY. THE SURFACE HIGH WILL MOVE EAST OF THE REGION. THIS WILL HELP
CLOUDS TO INCREASE AT THE 6-8KFT LEVEL FOR SATURDAY NIGHT. WINDS WILL
BE OUT OF THE SOUTH AT AROUND 6-8KTS FOR TODAY AND 3-5KTS FOR
TONIGHT./17/
&&
.PRELIMINARY POINT TEMPS/POPS...
JACKSON 65 46 69 51 / 0 6 14 66
MERIDIAN 66 40 68 52 / 0 4 13 50
VICKSBURG 66 49 70 52 / 1 9 16 75
HATTIESBURG 67 43 72 53 / 0 3 12 26
NATCHEZ 66 49 71 54 / 2 5 15 66
GREENVILLE 64 48 64 48 / 2 11 24 88
GREENWOOD 66 45 65 48 / 0 8 20 84
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...NONE.
LA...NONE.
AR...NONE.
&&
$$
17/BK
