FXUS64 KJAN 290949
AFDJAN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
349 AM CST SUN NOV 29 2009
.SHORT TERM...(TODAY THROUGH MONDAY NIGHT)...
THE PRIMARY WEATHER CONCERN WILL BE OUR CHANCE OF SHOWERS WITH A
COLD FRONT FOR THE TODAY TO MONDAY TIME RANGE. ALSO IF ANY
INSTABILITY WILL BE WITH THIS SYSTEM FOR ANY KIND OF CONVECTION.
LATEST SATELLITE IMAGERY SHOWED A FLAT UPPER RIDGE EXTENDING OVER
THE ARKLAMISS REGION WITH LOWER TO HIGHER LEVEL CLOUDS. A SHORT WAVE
WAS NOTED ACROSS THE REGION. WE WERE UNDER THE INFLUENCE OF WESTERLY
FLOW ALOFT. SURFACE HIGH PRESSURE WAS CENTERED OVER THE SOUTHERN GEORGIA
AND NORTHERN FLORIDA.
FOR TODAY THROUGH TONIGHT...THE SREF...EUROPEAN...NAM...GFS AND
UKMET HAVE REMAINED GENERALLY CONSISTENT IN THE TIMING OF THE RAIN AS WELL AS
THE FRONTAL PASSAGE. THE LOCAL WRF AND NATIONAL WRF SHOWS SHOWERS
WITH THE AID OF ISENTROPIC LIFT DEVELOPING THIS MORNING OVER THE DELTA
AND WESTERN AREAS FOR THIS MORNING. THE ACTIVITY WILL SPREAD ACROSS
MAINLY THE NORTHWEST HALF OF THE REGION DURING THIS AFTERNOON. THE
COLD FRONT WILL BEGIN TO ENTER THE REGION BY THIS EVENING. NET ISENTROPIC
LIFT AND GENERAL OMEGA WILL INCREASE ALONG THE FRONTAL BOUNDARY AND
BEHIND IT. LOCAL WRF AND NATIONAL WRF SHOWS A BAND OF MODERATE TO
LOCALLY HEAVY SHOWERS MOVING THROUGH THE REGION OVERNIGHT AROUND THE
FRONTAL BOUNDARY. INSTABILITY WILL CONTINUE TO BE RATHER WEAK WITH THIS
SYSTEM. AS FAR AS TEMPS ARE CONCERN WENT CLOSE TO MOS GUIDANCE WITH HIGHS
FROM THE MIDDLE TO UPPER 60S. SREF...MAV AND MOS GUIDANCE LOOKED A
LITTLE WARM. FOR TONIGHT WITH THE FRONTAL PASSAGE LOWS WILL RANGE
FROM THE UPPER 40S NORTH TO THE MIDDLE 50S SOUTHEAST. WENT
CLOSE MAV GUIDANCE. MOS LOOKED A LITTLE COOL WITH THE CLOUDS AND
SHOWERS...WHILE THE NAM AND SREF WAS A LITTLE WARM IN THE SOUTH.
AS FAR AS POPS ARE CONCERN WENT CLOSE TO MAV POPS FOR SCATTERED COVERAGE
ACROSS THE NORTHWEST HALF. FOR TONIGHT WENT ABOVE HIGH MAV POPS FOR
THE FRONTAL PASSAGE TO GET SOME GROUND ON MAV GUIDANCE.
FOR MONDAY AND MONDAY NIGHT...THE COLD FRONT WILL EXIT THE REGION BY
EARLY MONDAY MORNING. THE BULK OF THE SHOWERS WILL BE ON MONDAY
MORNING. AS WE GET INTO THE AFTERNOON THE ISENTROPIC LIFT BEHIND THE
FRONT WILL BEGIN TO DECREASE AS SHOWERS WILL DECREASE IN COVERAGE
FROM THE NORTH. FOR MONDAY NIGHT THE ISOLATED SHOWERS WILL BE CONFINED
IN THE EARLY EVENING ACROSS THE FAR SOUTHERN PORTION OF THE ARKLAMISS
REGION BEFORE DEPARTING BY MID EVENING. AS FAR AS TEMPS ARE CONCERN FOR
MONDAY WENT CLOSE TO MAV GUIDANCE WITH HIGHS FROM THE LOW-MID 50S
NORTH TO THE LOWER 60S SOUTH. OTHER GUIDANCE LOOKED GENERALLY CLOSE
TO THESE NUMBERS. FOR MONDAY NIGHT WENT WITH THE SLIGHTLY COOLER
MOS GUIDANCE WITH LOWS FROM THE MIDDLE 30S TO LOWER 40S. AS FAR AS
POPS ARE CONCERN WENT CLOSE TO MAV GUIDANCE FOR MONDAY MORNING...THEN
GRADUALLY REDUCED POPS FOR MONDAY AFTERNOON. FOR MONDAY NIGHT WENT WITH
LOW EARLY EVENING MAV POPS ACROSS THE FAR SOUTH./17/
.LONG TERM...TUESDAY THROUGH SUNDAY...A WET PATTERN FOR THE
EARLY PART OF THE EXTENDED FOR THE ARKLAMISS. COLD FRONT MOVED
THROUGH THE ARKLAMISS ON MONDAY AND HIGH PRESSURE FILTERS IN FOR THE
FIRST PART OF TUESDAY. AS THIS IS OCCURING...555DM MID LEVEL LOW
SYSTEM IS CHURNING ACROSS THE RIO GRANDE VALLEY. AHEAD OF THIS
SYSTEM...REFLECTION AT THE SFC IN THE FORM OF A 1007-1010MB LOW IS
LOCATED JUST OFF THE SOUTH CENTRAL TEXAS COAST ALONG PREVIOUS FRONTAL
BOUNDARY. AS THE MID LEVEL LOW BEGINS TO PROGRESS TO THE EAST...THE
SFC LOW MOVES EAST AS WELL. MODELS DIFFER IN THE TIMING AND PLACEMENT
OF THIS SFC LOW. BY 00Z WED. THE GFS HAS THE LOW JUST SOUTH OF NEW
ORLEANS WHEREAS THE ECMWF SHOWS IT STILL ALONG THE TEXAS COAST AND
SIMILAR SOLUTIONS TO THE ECMWF ARE ADVERTISED BY THE NAM AND SREF.
THIS SHOULD LEAVE MOST OF THE REGION FAIRLY DRY ON TUESDAY. THERE
COULD BE SOME LIGHT RAIN BEGINNING ON TUESDAY AFTERNOON DUE TO
ISENTROPIC LIFT ACROSS THE SOUTH AND HAVE INCLUDED SOME POPS IN
DURING THIS TIME PERIOD BUT LEFT NORTHERN SECTIONS DRY.
TIMING AND PLACEMENT DIFFERENCES BETWEEN MODELS LEAVE MUCH
UNCERTAINTY WITH MOST OF THE EXTENDED BUT IT LOOKS LIKE MOST OF THE
ARKLAMISS WILL SEE SOME RAIN WITH WED LOOKING TO BE THE WETTEST DAY.
MODELS INDICATE THAT THE HEAVIER/BULK OF THE RAIN WILL OCCUR
GENERALLY ALONG AND SOUTHEAST OF THE NATCHEZ TRACE WITH LESSER
AMOUNTS ACROSS THE MS DELTA. BY WED. MORNING...THE ECMWF AND OTHER
MODELS CONTINUE TO SHOW THE SFC LOW JUST TO OUR SOUTHWEST WITH THE
GFS FASTER WITH THE LOW ACROSS NW FL/S AL WITH THE MID LEVEL LOW
STILL ACROSS EAST CENTRAL TEXAS.
BY WED. NIGHT....THE BULK OF THE RAIN SHOULD MOVE OFF TO LOCATIONS
MUCH FARTHER EAST OF THE CWA AS THE MID LEVEL LOW ENTERS OUR REGION.
LINGERING LIGHT RAIN COULD AFFECT THE CWA THROUGH THURS. MORNING AND
HAVE TAPERED THIS FOR THE EAST/NORTHEAST WITH ONLY SLIGHT CHANCES IN
THE WEST PRIOR TO MIDNIGHT AND LEAVING ONLY SLIGHT CHANCES IN THE
EAST/NORTHEAST THROUGH DAYBREAK. CONDITIONS SHOULD REMAIN FAIRLY DRY
BEGINNING DURING THE DAY THURSDAY THROUGH MOST OF THE REST OF THE
PERIOD.
FOR THURS-FRI. THE LARGER SCALE TROUGH SWINGS ON THROUGH AND COLD
HIGH PRESSURE RESUMES AT THE SURFACE. MODELS DIFFER ONCE AGAIN PAST
THIS POINT. THE GFS QUICKLY MOVES THE SFC HIGH OFF TO THE EAST WITH
SOUTHERLY FLOW RETURNING LATE FRIDAY INTO SATURDAY AND THE ECMWF
DOES NOT MOVE THE UPPER TROUGH THROUGH AS FAST AND LINGERS NORTHERLY
FLOW. WITH THE ECMWF THE RETURN FLOW AND EASTWARD PUSH OF THE HIGH
DOES NOT OCCUR UNTIL LATE SUNDAY. GFS WANTED TO BRING RAIN CHANCES
BACK WITH THE NEXT SYSTEM BY SATURDAY BUT HAVE OPTED TO KEEP THESE
OUT OF THE FORECAST UNTIL THERE IS A LITTLE BETTER AGREEMENT.
OVERALL...TRIED TO STAY CLOSE TO MAV/MEX NUMBERS GIVEN UNCERTAINTIES
IN THE EXTENDED. HOWEVER...DID INCREASE POPS FOR TUES-WED IN THE
SOUTH WHERE THE BETTER POTENTIAL FOR RAIN EXISTS AND CUT NORTHERN
POPS DOWN SOME. TRIED TO FOLLOW THE SLIGHTLY SLOWER TIMING OF THE
ECMWF/SREF WHICH WAS ALSO A LITTLE WETTER. TEMPS LOOKED GOOD AND
LITTLE ADJ NECESSARY. /28/
&&
.AVIATION...GENERALLY VFR CONDITIONS ARE EXPECTED THIS MORNING
WITH CEILINGS FROM 7-11KFT...THOUGH SOME PATCHY FOG COULD IMPACT
SOUTHEAST MISSISSIPPI INCLUDING KHBG FROM 29/1000 UNTIL 29/1300
UTC...WHICH WOULD RESULT IN VISIBILITIES FALLING TO THE MVFR
CATEGORY. RELATIVELY LOW CONFIDENCE EXISTS IN THE FOG FORECAST DUE
TO THE POTENTIAL FOR LINGERING CLOUD COVERAGE. FOR DURING THE DAY
SUNDAY...SOUTHERLY WINDS WILL INCREASE TO 5 TO 10 KT...AS SURFACE
LOW PRESSURE AND AN ASSOCIATED COLD FRONT APPROACH THE AREA. AHEAD
OF THE FRONT...SCATTERED SHOWERS ARE EXPECTED THROUGH THE DAY TODAY
MAINLY ALONG AND NORTHWEST OF THE NATCHEZ TRACE PARKWAY...WHERE
CEILINGS WILL FALL TO THE MVFR CATEGORY. THE COVERAGE OF SHOWERS AND
LOWERED CEILINGS WILL EXPAND ACROSS THE ENTIRE AREA SUNDAY NIGHT AS
THE FRONT MOVES THROUGH. THE RAIN WILL BE LIGHT TO MODERATE IN
INTENSITY...WITH VISIBILITIES OCCASIONALLY REDUCED TO MVFR NEAR THE
MODERATE RAIN. FOR MONDAY THE RAINS WILL DECREASE FROM THE NORTH AS
WE PUSH INTO THE AFTERNOON HOURS./17/
&&
.PRELIMINARY POINT TEMPS/POPS...
JACKSON 68 53 57 40 / 27 89 61 7
MERIDIAN 67 51 59 39 / 16 73 66 8
VICKSBURG 69 52 57 41 / 35 100 54 6
HATTIESBURG 71 54 64 43 / 8 45 54 17
NATCHEZ 70 53 57 41 / 23 86 62 18
GREENVILLE 64 48 55 39 / 53 100 31 5
GREENWOOD 64 49 55 37 / 48 100 41 5
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...NONE.
LA...NONE.
AR...NONE.
&&
$$
17/28/
