889
AWUS01 KWNH 092005
FFGMPD
ALZ000-MSZ000-LAZ000-100100-
MESOSCALE PRECIPITATION DISCUSSION 0009
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
304 PM EST FRI JAN 09 2026
AREAS AFFECTED...SOUTH-CENTRAL LA INTO SOUTH-CENTRAL MS AND
WESTERN/CENTRAL AL
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY
VALID 092003Z - 100100Z
SUMMARY...RELATIVELY NARROW AXES (OR A SINGLE AXIS) OF HEAVY RAIN
APPEAR LIKELY TO MAINTAIN AN INCREASED FLASH FLOOD POTENTIAL INTO
THE EARLY EVENING FROM SOUTH-CENTRAL LA INTO SOUTH-CENTRAL MS AND
WESTERN/CENTRAL AL. 2 TO 4 INCHES AND AREAS OF FLASH FLOODING WILL
BE LIKELY WITHIN PORTIONS OF THIS CORRIDOR WITH LOCALLY HIGHER
RAIN TOTALS POSSIBLE.
DISCUSSION...RADAR IMAGERY FROM 1945Z SHOWED A PERSISTENT AXIS OF
MODERATE TO HEAVY RAIN FROM NEAR THE SOUTHEASTERN LA/MS BORDER
INTO SOUTH-CENTRAL MS AND WESTERN AL WHICH HAS BEEN IN ROUGHLY THE
SAME LOCATION OVER THE PAST 3-4 HOURS. EMBEDDED HOURLY RAINFALL
HAS BEEN OBSERVED IN THE 1-2 INCH RANGE AT TIMES AND ROUGHLY 2 TO
4 INCHES HAVE FALLEN FROM NEAR BATON ROUGE INTO SOUTH-CENTRAL MS
AS FAR EAST AS WAYNESBORO, MS SINCE EARLY THIS MORNING. A
COMBINATION OF RAIN-COOLED OUTFLOW AND A SLIGHTLY ELEVATED AXIS OF
CONVERGENCE LOCATED WITHIN 925-850 MB LAYER HAVE HELPED TO FOCUS
THESE AREAS OF HEAVY RAIN OVER THE PAST FEW HOURS WHERE MLCAPE HAS
INCREASED INTO THE 500-1500 J/KG RANGE FROM THE SOUTHERN MS/AL
BORDER TOWARD LAKE PONTCHARTRAIN (VIA SPC MESOANALYSIS DATA).
ADDITIONAL RAINFALL WAS OCCURRING FARTHER NORTH IN AL ALONG THE
ELEVATED CONVERGENCE AXIS WHERE 2 TO 3 INCHES WAS REPORTED OVER
THE PAST 6 HOURS, BUT A LACK OF INSTABILITY HAS TEMPERED RAINFALL
RATES ACROSS NORTHERN LOCATIONS. RADAR IMAGERY ALSO SHOWED
ADDITIONAL THUNDERSTORMS BUILDING OVER THE I-10 CORRIDOR OF
SOUTH-CENTRAL LA, ROOTED NEAR THE SURFACE WITHIN WEAKER/MORE
SUBTLE AXES OF NEAR SURFACE CONVERGENCE.
RAP FORECAST GUIDANCE SUGGESTS AN INFLECTION POINT ALONG THE
CONVERGENCE AXIS (CURRENTLY OVER THE SOUTH-CENTRAL MS/AL BORDER)
WILL ADVANCE NORTHEASTWARD IN THE SHORT TERM WHILE THE AXIS OF
CONVERGENCE TO ITS WEST LIFTS SLIGHTLY NORTH. MEANWHILE, THE WSW
TO ENE ORIENTED OUTFLOW BOUNDARY IN PLACE OVER SOUTH-CENTRAL MS IS
LIKELY TO CONTINUE TO SERVE AS A FOCUS FOR ADDITIONAL THUNDERSTORM
DEVELOPMENT. THEREFORE, EXPECTATIONS ARE FOR CONTINUED
THUNDERSTORMS OVER THE REGION THROUGH EARLY EVENING, INITIATING
ALONG AND JUST NORTH OF THE SURFACE OUTFLOW AND FARTHER NORTH ON
ELEVATED CONVERGENCE WITH TRAINING VIA MEAN MOVEMENT OFF TOWARD
THE ENE. EMBEDDED SHORT TERM TRAINING MAY ALSO OCCUR WITH THE
THUNDERSTORMS MOVING NORTHWARD THROUGH SOUTH-CENTRAL LA.
HOURLY RAINFALL OF 1 TO 2 INCHES, BUT LOCALIZED HOURLY RAINFALL IN
EXCESS OF 2 INCHES IS EXPECTED THROUGH EARLY EVENING FROM SOUTHERN
PORTIONS OF THE LOWER MISSISSIPPI VALLEY INTO WESTERN/CENTRAL AL.
THE BETTER INSTABILITY IS FORECAST TO REMAIN SITUATED WEST OF THE
MS/AL BORDER BUT POCKETS OF LOCALLY HIGHER INSTABILITY INTO
PORTIONS OF AL MAY ALSO SUPPORT FLASH FLOODING TO THE EAST AS
WELL. GIVEN DRY ANTECEDENT CONDITIONS LEADING UP TO THIS EVENT,
FLASH FLOODING POTENTIAL WILL BE GREATEST OVER URBAN AREAS AND
WHERE HEAVY RAIN HAS FALLEN OVER THE PAST 12 HOURS.
OTTO
..PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...BMX...JAN...LCH...LIX...MOB...
ATTN...RFC...ALR...ORN...NWC...
LAT...LON 33568684 33488628 33168594 32648596 32198649
31858711 31258872 30868957 30379076 30359177
30639220 31179203 31969105 32449012 32698924
33208778
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