River Flood Warning 63, NWS Jackson, MS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
330 PM CDT SUN MAY 2 2010

.SHORT TERM...(TONIGHT THROUGH TUESDAY NIGHT)...
THE PRIMARY CONCERN WILL BE FOR ISOLATED SEVERE STORM POTENTIAL FOR THIS
EVENING UNTIL THE FRONTAL BOUNDARY PASSES BY. OF THE SECONDARY
CONCERNS WILL BE THE PASSING SHORT WAVE FOR TUESDAY FOR SOME RAIN
FOLLOWED BY POPS AND TEMPS FOR THE PERIOD.

THE LATEST SATELLITE IMAGERY CONTINUES TO SHOW THE TROPICAL PLUME
OF MOISTURE CONTINUING OVER THE REGION WITH THE FRONTAL BOUNDARY
SLOWLY APPROACHING FROM THE WEST. THIS WAS DUE TO AN UPPER TROUGH
OVER THE PLAINS WHICH WAS COMPOSE OF SEVERAL SHORT WAVES ROTATING
AROUND THE BASE OF IT. AREA RADARS SHOWED THAT MOST OF THE
CONVECTIVE ACTIVITY HAS MOVED EAST OF THE REGION.

FOR TONIGHT EXPECT THE FRONTAL BOUNDARY TO MOVE THROUGH THE REGION. THERE
WILL STILL BE ENOUGH SHEAR AND INSTABILITY FOR SOME ISOLATED SEVERE STORMS
TO DEVELOP UNTIL THE FRONTAL BOUNDARY MOVES THROUGH THE REGION BY EARLY
MONDAY. OUR CHANCES OF RAIN WILL DECREASE FROM WEST TO EAST DURING
THE NIGHT. IT WILL BE A MILD NIGHT WITH LOWS FROM THE MIDDLE 50S WEST
TO THE MIDDLE 60S EAST. WENT CLOSE TO MOS GUIDANCE. DID A BLEND OF
NAM AND MAV GUIDANCE ON POPS WITH THE BEST POPS EAST OF INTERSTATE
55.

FOR MONDAY AND MONDAY NIGHT DRY WEATHER WILL MOVE INTO THE REGION
FROM THE WEST. WE WILL HAVE SOUTHWEST FLOW ALOFT AHEAD OF A WEAK
SHORT WAVE. THIS WILL BRING SOME HIGH CLOUDS TO THE REGION BY MONDAY
NIGHT. WENT CLOSE TO MAV GUIDANCE ON DAYTIME HIGHS WITH READINGS FROM
THE MIDDLE TO UPPER 80S. LOWS MONDAY NIGHT WILL BE FROM THE MIDDLE
50S TO THE LOWER 60S WITH A SLIGHT ADJUSTMENT TO MOS GUIDANCE.

FOR TUESDAY AND TUESDAY NIGHT...OUR WEAK SHORT WAVE WILL PASS THROUGH
THE REGION ON TUESDAY. THERE WILL BE LIMITED INSTABILITY FOR A LOW
CHANCE OF THUNDERSHOWERS ON TUESDAY AS THE SHORT WAVE PASSES THROUGH THE
ARKLAMISS. THIS WILL BE OVER THE SOUTHEAST QUARTER OF THE REGION. BY TUESDAY
NIGHT DRY AIR WILL MOVE BACK INTO THE REGION AFTER THE SHORTWAVE
EXITS THE REGION. AS FAR AS TEMPS ARE CONCERN WENT CLOSE TO MAV GUIDANCE ON
TUESDAYS HIGHS WITH READINGS FROM THE MIDDLE TO UPPER 80S. FOR LOWS
WENT CLOSE TO MOS GUIDANCE WITH READINGS FROM THE MIDDLE 50S TO
LOWER 60S. /17/

LONG TERM...(WEDNESDAY THROUGH SUNDAY)...A DRY STRETCH OF WEATHER
CAN BE EXPECTED WEDNESDAY THROUGH FRIDAY AS ZONAL FLOW ALOFT
COMBINES WITH SURFACE HIGH PRESSURE CENTERED OVER THE CAROLINAS.
THIS WILL LEAVE THE ARKLAMISS IN SOUTHERLY LOW LEVEL FLOW ALLOWING
WARM GULF AIR TO SURGE NORTH THROUGH THE END OF THE WEEK. A COLD
FRONT IS PROGGED TO CROSS THE REGION FRIDAY NIGHT BRINGING A RETURN
OF SHOWERS AND THUNDERSTORMS. NOT OVERLY EXCITED ABOUT WIDESPREAD
SEVERE POTENTIAL AT THIS TIME AS BEST DYNAMICS APPEAR TO BE CONFINED
WELL TO THE NORTH. WITH THAT SAID...0-6 KM SHEAR OF 40-50KTS COUPLED
WITH SFC BASED BUOYANCY OF 1500-2000J/KG IS CERTAINLY CAPABLE OF
PRODUCING RIGOROUS CONVECTION IF LIFT ALONG THE FRONT CAN BREAK THE
MEAGER 30-70J/KG SFC BASED CIN THAT WILL BE IN PLACE. PRIMARY
THREATS FOR ANY STORMS THAT DO DEVELOP WILL BE LARGE HAIL AND GUSTY
WINDS...WITH A MUCH LOWER RISK FOR TORNADOES.

SHOWER AND THUNDERSTORM CHANCES LOOK TO DIMINISH SLIGHTLY SATURDAY
AFTERNOON INTO SATURDAY NIGHT AS THE BOUNDARY PUSHES SOUTH HOWEVER
BOTH GFS/ECMWF SHOW SHOWERS RETURNING SUNDAY AS SOUTHERLY FLOW AND
ISENTROPIC LIFT ABOVE 900MB RETURN TO THE REGION. RELATIVELY WEAK
LAPSE RATES SHOULD KEEP THUNDER SOMEWHAT LIMITED ALTHOUGH ELEVATED
CONVECTION IS NOT OUT OF THE QUESTION AND WILL KEEP THUNDER
MENTIONED IN THE FORECAST AT THIS TIME.

AS FOR TEMPS...ABOVE NORMAL AFTERNOON HIGHS CAN BE EXPECTED THROUGH
THURSDAY HOWEVER GFS MOS LOOKED A LITTLE OVERZEALOUS TUESDAY AND
WEDNESDAY AND DID KNOCK GFS MOS HIGHS A DEGREE OR TWO AT A COUPLE
SPOTS DURING THIS TIME. HIGHS LOOK TO DROP BACK TO NEAR NORMAL
FRIDAY THROUGH SUNDAY BEHIND THE FRONT. OVERNIGHT LOWS NEXT WEEK
WILL ALSO BE RUNNING ABOVE NORMAL UNTIL THE WEEKEND WHEN A RETURN TO
NEAR NORMAL IS EXPECTED. /BK/

&&

.AVIATION...AREAS OF MVFR-VFR CEILINGS ACROSS THE AREA.
CIGS/VISIBILITIES WILL BE REDUCED TO IFR/LIFR AT TIMES IN RAIN AS LOCALLY
HEAVY RAINFALL OCCURS WITH SOME OF THE STORMS. BREEZY SSE WINDS OF
12-18KTS WITH GUSTS TO 22KTS ARE EXPECTED UNTIL EARLY EVENING WHEN
THEY DIE DOWN TO 10KTS OR SO AS THE STRONGER GRADIENT WINDS MOVE TO
NERN MS.VFR CONDITIONS WILL DEVELOP FROM WEST TO EAST BEHIND THE
WEAK BOUNDARY AS IT MOVES ACROSS THE REGION OVERNIGHT. PATCHY FOG
WILL DEVELOP ACROSS THE REGION AFTER 10Z OVER THE EAST AND SOUTHEAST
AND WILL LIFT BY 14Z./17/

&&

.PRELIMINARY POINT TEMPS/POPS...
JACKSON       63  87  58  88 /  37   7   8  16
MERIDIAN      65  89  55  88 /  66  11   8  25
VICKSBURG     60  87  58  88 /  22   7   8  13
HATTIESBURG   67  89  62  89 /  60  12  13  27
NATCHEZ       61  86  59  85 /  21   1   9  13
GREENVILLE    60  87  59  87 /  21   8   6  12
GREENWOOD     59  86  55  88 /  23   8   7  12

&&

.JAN WATCHES/WARNINGS/ADVISORIES...
MS...FLASH FLOOD WATCH THROUGH THIS EVENING FOR MSZ018-019-025>042.

LA...FLASH FLOOD WATCH THROUGH THIS EVENING FOR LAZ007>009.

AR...FLASH FLOOD WATCH THROUGH THIS EVENING FOR ARZ074-075.

&&