Flash Flood Warning 20, NWS Memphis, TN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEMPHIS TN
640 AM CDT SAT APR 27 2013

.DISCUSSION...

UPDATED FOR 12Z AVIATION DISCUSSION

&&

.PREV DISCUSSION... /ISSUED 416 AM CDT SAT APR 27 2013/

DISCUSSION...
LOTS OF RAIN ON THE RADAR THIS MORNING...BUT NOTHING APPROACHING
STRONG OR SEVERE LEVELS. IF THERE IS ANY EXISTING THREAT FROM THE
CURRENT STORMS...OTHER THAN LIGHTNING...IT WOULD BE LOCALIZED
FLOODING. PORTIONS OF NORTHWEST TENNESSEE...NORTHEAST ARKANSAS AND
THE MISSOURI BOOTHEEL HAVE ALREADY RECEIVED OVER 2.5 INCHES OF RAIN
OVER THE PAST 12 HOURS OR SO. ADDITIONAL RAINFALL COULD RESULT IN
FLOODING PROBLEMS ALONG LOW WATER CROSSINGS AND OTHER FLOOD PRONE
AREAS. THREE HOUR FLASH FLOOD GUIDANCE INDICATES THAT MOST AREAS
THAT HAVE ALREADY RECEIVED HEAVY RAINFALL CAN HANDEL ANOTHER 1-2
INCHES OF RAIN IN A 3 HOUR TIME PERIOD BEFORE ANY WIDESPREAD
PROBLEMS ARE EXPECTED. DUAL POL INSTANTANEOUS RAINFALL RATES
INDICATE RAINFALL RATES ARE UP TO 2 INCHES PER HOUR...BUT THESE
EXCESSIVE RATES SHOULD NOT LAST FOR ANY PROLONGED PERIOD OF TIME
AT ANY GIVEN LOCATION. WILL CONTINUE TO MONITOR THE FLOOD
POTENTIAL...AND ADD IT AS A THREAT IN THE HWO...BUT DO NOT ANTICIPATE
THE NEED FOR A FLASH FLOOD WATCH AT THIS TIME.

RAIN AND THUNDERSTORMS WILL CONTINUE TODAY...ALL OF THE MIDSOUTH
CAN EXPECT TO EXPERIENCE THUNDERSTORMS TODAY INTO THE OVERNIGHT
HOURS. THE SEVERE POTENTIAL LOOKS MARGINAL...GREATEST ACROSS
NORTHERN MISSISSIPPI. ALOFT...WE REMAIN IN A SPLIT FLOW PATTERN
WITH A POSITIVELY TILTED TROUGH MOVING TO THE EAST ACROSS THE
AREA. NO SIGNIFICANT DYNAMIC ENERGY IS IN PLACE TO SUPPORT
WIDESPREAD SEVERE WEATHER. ABOUT ALL WE CAN SEE IN THE UPPER
LEVELS IS 60-70 KTS OR FAIRLY UNIDIRECTIONAL FLOW AND ONLY
30-50KTS AT THE MID AND LOW LEVELS. AT THE SURFACE..A WARM FRONT
WILL LIFT TO THE NORTH ACROSS THE MIDSOUTH ALLOWING A DEEP WARM
AIRMASS TO BUILD OVER THE REGION. DEW POINTS WILL SURGE INTO THE
UPPER 50S OR LOW 60S BY THIS AFTERNOON. A SURFACE LOW IS EXPECTED
TO TRACK ACROSS EAST ARKANSAS AND ACROSS THE MISSOURI BOOTHEEL THIS
AFTERNOON...LIKELY ENHANCING SHEAR NEAR ITS TRACK...BUT OVERALL
SHEAR PROFILES DO NOT LOOK IMPRESSIVE. ADDITIONALLY...GUIDANCE
INSTABILITY PARAMETERS ARE LIKELY EXAGGERATED. IT DOES NOT LOOK
LIKELY THAT WE WILL BE ABLE TO WARM SIGNIFICANTLY TODAY UNDER
DENSE CLOUD COVER AND WITH ONGOING PRECIPITATION. NORTH
MISSISSIPPI LIKELY STANDS THE GREATEST CHANCE OF APPROACHING
GUIDANCE FORECAST CAPE VALUES IN EXCESS OF 1200J/KG...BUT THAT IS
ONLY IF THERE IS A FEW BREAKS IN THE CLOUD COVER TO ALLOW SURFACE
WARMING. WARM ADVECTION IS NOT LIKELY GOING TO BE ENOUGH TO WARM
TEMPERATURES IN THE MIDDLE 70S. WILL ADVERTISE A LOW END SLIGHT
RISK FOR SEVERE STORMS ACROSS NORTH MISSISSIPPI AND GENERAL
STRONG THUNDERSTORMS ELSEWHERE. THE ONLY FLY IN THE OINTMENT
FARTHER NORTH FOR SEVERE WEATHER WILL BE THE POTENTIAL FOR
LOCALIZED SHEAR ENHANCEMENT NEAR THE SURFACE LOW. HOWEVER...AT
THIS TIME...THINK THAT THREAT IS LOW ENOUGH TO STICK WITH ONLY
STRONG WORDING.

TONIGHT...ANY SEVERE THREAT WILL DIMINISH AND A WEAKENING COLD
FRONT WILL GRADUALLY SHIFT ACROSS THE MIDSOUTH. THE AIRMASS BEHIND
THE FRONT IS NOT A LOT DIFFERENT THAN AHEAD OF IT...BUT WINDS WILL
SHIFT FROM THE WEST TO NORTHWEST MARKING ITS PASSAGE. TEMPERATURES
SUNDAY MAY EVEN BE WARMER TOMORROW THAN TODAY AS THE RESULT OF
MORE SUNSHINE...ESPECIALLY IN EAST ARKANSAS. MUCH OF NORTH
MISSISSIPPI AND WEST TENNESSEE...NEAR THE ALABAMA STATE LINE AND
TENNESSEE RIVER WILL REMAIN CLOUDY. A FEW SHOWERS MAY ALSO LINGER
IN EASTERN PORTIONS OF NORTH MISSISSIPPI...BUT NO STORMS ARE
EXPECTED TO BE SEVERE.

MONDAY THROUGH MIDWEEK SHOULD BE MOSTLY DRY AND WARM. HIGHS WILL
APPROACH THE MIDDLE 80S BY WEDNESDAY AS RIDGE BUILDS OVER THE
MIDSOUTH AND SHIFTS TO THE EAST. BY MIDDAY WEDNESDAY RETURN FLOW
WILL SETUP ACROSS THE MIDSOUTH...AND THE CHANCE FOR A FEW SHOWERS
WILL RETURN TO THE FORECAST. GUIDANCE WINDS ARE PRETTY IMPRESSIVE
THURSDAY AFTERNOON INTO FRIDAY...FEATURING SUSTAINED SPEEDS IN THE
MIDDLE 20S AS A DEEP TROUGH DIGS OVER THE PLAINS. THERE IS
CONSIDERABLE DISAGREEMENT IN GUIDANCE THURSDAY INTO THE WEEKEND.
THE GFS HAS A MORE PROGRESSIVE SOLUTION WHILE THE ECMWF KEEPS A
DEEP CUTOFF LOW OVER THE SOUTHERN PLAINS FOR SEVERAL DAYS. BOTH
MODELS FEATURE A SIGNIFICANT TROUGH...WHICH COULD PUT US BACK IN
RECORD LOW TEMPERATURE TERRITORY TOWARD THE END OF THE FORECAST
PERIOD. PORTIONS OF THE MIDSOUTH COULD SEE A LATE SPRING/EARLY MAY
FROST FRIDAY AND OR SATURDAY MORNING.

30/SIRMON

&&

.AVIATION...
12Z TAF CYCLE

CEILINGS WILL LOWER TO MVFR/IFR LEVELS THIS MORNING AND REMAIN
THERE FOR MOST OF THE FORECAST PERIOD WITH SOME BRIEF PERIODS WHEN
CEILINGS RETURN TO VFR LEVELS. PERIODS OF SHOWERS AND THUNDERSTORMS
WILL OCCUR THROUGH MOST OF THE FORECAST PERIOD WITH LOWER
VISIBILITIES AT TIMES DUE TO THE RAIN. WINDS WILL BE MAINLY FROM
THE SOUTH AROUND 10 KNOTS FOR MUCH OF THE FORECAST PERIOD.

ARS

&&

.PRELIMINARY POINT TEMPS/POPS...
MEM  71  58  72  54 / 100  60  30  10
MKL  68  57  71  50 / 100  70  30  10
JBR  68  55  70  49 / 100  50  20   0
TUP  73  62  73  54 / 100  70  60  20

&&

.MEG WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
MO...NONE.
MS...NONE.
TN...NONE.
&&

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE MEMPHIS TN
334 AM CDT SAT APR 27 2013

ARZ008-009-017-018-026>028-035-036-048-049-058-MOZ113-115-
MSZ001>017-020>024-TNZ001>004-019>021-048>055-088>092-281030-
ALCORN-BENTON MS-CALHOUN-CARROLL-CHESTER-CHICKASAW-CLAY-COAHOMA-
CRAIGHEAD-CRITTENDEN-CROCKETT-CROSS-DESOTO-DECATUR-DUNKLIN-DYER-
FAYETTE-GIBSON-GREENE-HARDEMAN-HARDIN-HAYWOOD-HENDERSON-HENRY-
ITAWAMBA-LAFAYETTE-LAKE-LAUDERDALE-LAWRENCE-LEE AR-LEE MS-MADISON-
MARSHALL-MCNAIRY-MISSISSIPPI-MONROE-OBION-PANOLA-PEMISCOT-
PHILLIPS-POINSETT-PONTOTOC-PRENTISS-QUITMAN-RANDOLPH-SHELBY-
ST. FRANCIS-TALLAHATCHIE-TATE-TIPPAH-TIPTON-TISHOMINGO-TUNICA-
UNION-WEAKLEY-YALOBUSHA-
334 AM CDT SAT APR 27 2013

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF EAST ARKANSAS...
THE MISSOURI BOOTHEEL...NORTH MISSISSIPPI...AND WEST TENNESSEE.

.DAY ONE...TODAY AND TONIGHT

A FEW STRONG TO PERHAPS SEVERE THUNDERSTORMS ARE POSSIBLE INTO THIS
EVENING...PREDOMINANTLY SOUTH OF I-40. DAMAGING WINDS AND PERHAPS
LARGE HAIL WILL BE THE PREDOMINANT THREATS FOR ANY THUNDERSTORMS
THAT REACH SEVERE LIMITS.

IN ADDITION...LOCALIZED FLASH FLOODING FROM HEAVY RAINFALL IS ALSO
POSSIBLE. AREA RIVERS AND OTHER WATERWAYS WILL LIKELY EXPERIENCE
RISES AS AS WELL.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED INTO THIS EVENING IN SUPPORT OF
SEVERE WEATHER OPERATIONS.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MEMPHIS TN
617 AM CDT SAT APR 27 2013

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0615 AM     FLASH FLOOD      BRIGHTON                35.48N 89.74W
04/27/2013                   TIPTON             TN   LAW ENFORCEMENT

            8-10 INCHES OF WATER OVER OLD HWY 51 NEAR BRIGHTON
            ELEMENTARY SCHOOL. OTHER ROADS IN TIPTON COUNTY ALSO HAVE
            SEVERAL INCHES WATER OVER THEM.

&&

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PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MEMPHIS TN
752 AM CDT SAT APR 27 2013

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0750 AM     FLASH FLOOD      JACKSON                 35.63N 88.83W
04/27/2013                   MADISON            TN   TRAINED SPOTTER

            A STREET AND NORTH KENTUCKY STREET IMPASSABLE

&&

CDG