300
FXUS64 KJAN 200217 AAA
AFDJAN
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JACKSON MS
917 PM CDT SUN MAY 19 2013
UPDATE
OVERALL QUIET NIGHT TONIGHT AS SHORTWAVE RIDGING AND HIGH PRESSURE
WILL KEEP THE REGION DRY TONIGHT. THE STRONG UPPER TROUGH OVER THE
CENTRAL PLAINS WILL GRADUALLY PROPAGATE TO THE EAST AND SOME OF THE
CONVECTIVE HIGH CLOUDS WILL MOVE IN THE NORTHWESTERN AREAS OVERNIGHT
TONIGHT. HAD TO MODIFY SKY GRIDS AS MOST OF THE REGION HAS CLEARED
FROM CLOUDS FROM EARLIER AS SHORTWAVE RIDGE AXIS MOVES THROUGH THE
REGION. THERE WILL BE THE POTENTIAL FOR SOME LOW STRATUS/PATCHY FOG
DUE TO CAPPED LOW LEVEL MOISTURE...CLEAR SKIES AND LIGHT WINDS.
HOWEVER...LOW LEVEL FLOW PER MODEL SOUNDINGS LOOK STRONG ENOUGH TO
LIMIT FOG POTENTIAL AND FAVOR MORE STRATUS DEVELOPMENT. SREF PROBS
WERE REALLY HIGHLIGHTING AREAS ALONG AND SOUTH OF I-20 CORRIDOR FOR
LOW CLOUDS/PATCHY FOG. TEMPS OVERNIGHT LOOK GOOD. REST OF THE
FORECAST IS ON TRACK. /DC/
AVIATION
THE PRIMARY AVIATION CONCERN FOR LATER TONIGHT INTO
MONDAY MORNING WILL BE AN EPISODE OF MVFR/IFR CATEGORY STRATUS...AND
PERHAPS SOME FOG...IMPACTING MOST TAF SITES IN SOUTHERLY LOW-LEVEL
FLOW. EXPECT CEILINGS AND ANY FOG TO LIFT AND BREAK UP BY MID TO
LATE MONDAY MORNING WITH VFR CONDITIONS THEN PREVAILING THROUGH
MONDAY EVENING. /EC/
PREV DISCUSSION
/ISSUED 325 PM CDT SUN MAY 19 2013/
SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT...
THE PRIMARY CONCERNS WILL BE THE POTENTIAL FOR A FEW STRONG TO
SEVERE STORMS FOR TUESDAY AFTERNOON AND NIGHT WITH THE RISK OF
QUARTER SIZED HAIL...LOCALLY HEAVY RAINFALL AND SOME GUSTY WINDS. ALSO AN
ISOLATED STORM IN THE SOUTH HALF FOR THE REST OF THE AFTERNOON ALONG
WITH POPS AND TEMPS.
LATEST SATELLITE IMAGERY SHOWED THE REGION UNDER THE INFLUENCE OF A
SHORTWAVE RIDGE WITH WEAK MOISTURE CONVERGENCE...WHICH WAS BEING
FLANKED BY A STRONG UPPER TROUGH OVER THE PLAINS AND SHORT WAVE
TROUGHING OVER THE SOUTHEAST US. SKIES WERE PARTLY CLOUDY OVER THE REGION
FOR THIS AFTERNOON WITH HIGH DEBRIS CLOUDS COMING FROM THE PLAINS
STORM SYSTEM. SO FAR THE RADAR HAS BEEN CLEAR...BUT THERE IS STILL
THE SLIM CHANCE OF AN ISOLATED POSSIBLY STRONG STORM ACROSS THE
SOUTH HALF FOR THE REST OF THE AFTERNOON WITH INSTABILITY AND SOME
MOISTURE TRANSPORT IN PLACE.
FOR TONIGHT...THE UPPER PLAINS SYSTEM WILL CREEP SLOWLY TOWARD THE REGION
AS UPPER SHORT WAVE RIDGING AXIS MOVES EAST OF THE REGION BY EARLY
MONDAY. ONCE AGAIN LOW LEVEL BOUNDARY LAYER MOISTURE WILL INCREASE WITH
SOUTHERLY FLOW. THIS WILL ALLOW ANOTHER ROUND OF STRATUS ALONG WITH SOME
PATCHY SHALLOW FOG TO DEVELOP AFTER MIDNIGHT. BELIEVE THAT THE LOW
LEVEL FLOW WILL HINDER ANY SIGNIFICANT FOG DEVELOPMENT...DESPITE MODELS
FAVORING SOME FOG POTENTIAL. IT WILL BE ANOTHER MUGGY NIGHT WITH
LOWS FROM THE MID 60S TO AROUND 70. MOS AND MAV GUIDANCE LOOKED A
LITTLE COOL WITH THE LOW LEVEL BOUNDARY MOISTURE IN PLACE. SO WENT
WITH MILDER GFS GUIDANCE.
FOR MONDAY AND MONDAY NIGHT...THE STRATUS WILL LIFT BY LATE MORNING.
THE AXIS OF THE SOUTHERN PLAINS TROUGH WILL PUSH DOWN INTO THE
SOUTHERN PLAINS AS LOW LEVEL INFLOW INCREASES ACROSS THE REGION. THE
SPC WRF TRIES TO SHOW SOME CONVECTION ACROSS THE DELTA WHILE ALL THE
OTHER MODELS AND WRF GUIDANCE WERE GENERALLY CLEAR. THINK THAT THE
CAP WILL HINDER ANY DEVELOPMENT DURING THE DAY. PUT THE BEST LOW DRY
POPS IN THE WEST. FOR MONDAY NIGHT 500 MB HEIGHTS WILL START TO
GRADUALLY LOWER FROM THE NORTHWEST. PUT IN SLIGHT TEEN POPS FOR
CONVECTION IN THE NORTHWEST AFTER MIDNIGHT. JUST IN CASE THERE WOULD
BE AN OUTFLOW BOUNDARY COMING FROM THE STORMS TO THE NORTHWEST.
EXPECT ANOTHER ROUND OF STRATUS...BUT ONCE AGAIN THE LOW LEVEL FLOW
WILL HINDER ANY SIGNIFICANT FOG DEVELOPMENT AFTER MIDNIGHT...DESPITE
MODEL PROGS. HIGHS ON MONDAY WILL BE FROM THE UPPER 80S TO AROUND
90. LOWS WILL BE FROM THE MID 60S TO THE LOWER 70S. WENT WITH GMOS
GUIDANCE ON HIGHS AND ONCE AGAIN MILDER GFS GUIDANCE ON LOWS.
FOR TUESDAY AND TUESDAY NIGHT...500 MB HEIGHTS WILL DROP FROM THE
NORTHWEST DURING THE PERIOD AS THE UPPER TROUGH AXIS PUSHES TOWARD
THE LOWER MISSISSIPPI VALLEY REGION. OUR CHANCES OF CONVECTION WILL
GRADUALLY INCREASE ACROSS THE REGION DURING THE PERIOD. THERE WILL
BE ENOUGH INSTABILITY AND LIMITED JET DYNAMICS FOR A FEW STRONG TO
SEVERE STORMS FOR TUESDAY AFTERNOON AND NIGHT. PWATS WILL INCREASE
TO AROUND 1.7 INCHES(LOCALLY HEAVY RAINFALL). THE BULK SHEAR WILL
NOT BE IMPRESSIVE WITH THIS SYSTEM THROUGH MOST OF TUESDAY NIGHT. A
MIDLEVEL JET OF AROUND 50 KNOTS WILL MOVE ACROSS THE DELTA REGION
FOR TUESDAY NIGHT. CAPES WILL BE FROM 1500 TO 3500 J/KG...SHOWALTERS
-3 TO -7. AN MCS WILL MOVE ACROSS THE REGION DURING THE PERIOD FROM
THE NORTHWEST TUESDAY AFTERNOON AND NIGHT. SO AS FAR AS TEMPS ARE
CONCERN HIGHS WILL BE FROM THE MID TO UPPER 80S. LOWS WILL BE FROM
THE MID 60S TO AROUND 70S. WENT CLOSE TO GMOS GUIDANCE ON HIGHS AND
MILDER GFS GUIDANCE ON LOWS. FOR POPS WENT CLOSE TO MAV GUIDANCE./17/
/PREVIOUS DISCUSSION...
LONG TERM...WEDNESDAY THROUGH SUNDAY...THE WEAKENING UPPER LEVEL
TROUGH WILL SWING ACROSS OUR CWA WEDNESDAY BUT MODELS HAVE BACKED
OFF ON ANY FROPA IN OUR CWA AS THE FRONT FIZZLES NORTH OF OUR AREA.
OVERALL...THERMODYNAMIC PARAMETERS LOOK LESS FAVORABLE FOR SEVERE
WEATHER WEDNESDAY INTO THURSDAY BUT WL STILL HAVE A WARM MOIST
AIRMASS IN PLACE WITH RATHER STEEP MID LEVEL LAPSE RATES SO A FEW
STRONG STORMS WILL BE HARD TO RULE OUT. THE UPPER TROUGH AXIS WILL
BE EAST OF OUR CWA THURSDAY BUT NORTHWEST FLOW ALOFT WILL CONTINUE
OVER OUR CWA THROUGH SATURDAY. ALTHOUGH MOST OF THE CONVECTION WILL
SHOULD SHOW A DISTINCT DIURNAL TREND...MODELS INDICATE DISTURBANCES
ALOFT IN THE NW FLOW MAY SET OFF SOME CONVECTION OVER NIGHT THURSDAY
AND FRIDAY NIGHTS. IN ADDITION...BOTH GFS AND ECMWF SHOW A SURFACE
HIGH DROPPING OVER THE GREAT LAKES REGION FRIDAY NIGHT THAT MAY PUSH
A WEAK BACKDOOR COLD FRONT INTO OUR CWA SATURDAY. RIDGING SURFACE
AND ALOFT IS EXPECTED TO BUILD OVER OUR REGION SUNDAY RESULTING IN
DRY WEATHER. /22/17/
PRELIMINARY POINT TEMPS/POPS
JACKSON 68 90 67 89 / 5 10 7 10
MERIDIAN 67 92 66 90 / 5 8 6 8
VICKSBURG 70 89 71 89 / 5 11 8 15
HATTIESBURG 69 91 67 90 / 8 8 7 8
NATCHEZ 70 89 71 88 / 7 11 10 18
GREENVILLE 69 89 71 88 / 4 11 17 29
GREENWOOD 69 91 68 88 / 4 10 13 19
JAN WATCHES/WARNINGS/ADVISORIES
MS...NONE.
LA...NONE.
AR...NONE.
DC/EC/17/22
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page