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000
FXUS64 KHUN 172242 AAA
AFDHUN

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE HUNTSVILLE AL
542 PM CDT MON JUN 17 2013

.UPDATE...
FOR 00Z TAFS

&&

.DISCUSSION...
/ISSUED 403 PM CDT MON JUN 17 2013/
QUITE AN ACTIVE WEATHER DAY CONTINUES ACROSS THE TENNESSEE VALLEY
THIS AFTERNOON AS AN OUTFLOW BOUNDARY FROM REMNANT CONVECTION OVER
CENTRAL MS CONTINUES PUSHING NORTHEASTWARD ACROSS THE CWA. A FEW
STRONG TO SEVERE STORMS OCCURRED, MAINLY WITH A DAMAGING WIND THREAT.
IN ADDITION, VERY HEAVY RAINFALL ALSO ACCOMPANIED THESE STORMS AS
THEY TRAVERSED THE AREA, WITH A FEW INSTANCES OF NUISANCE/FLASH
FLOODING REPORTED. ALL OF THIS ACTIVITY IS IN RESPONSE TO A 500MB
DISTURBANCE PUSHING ACROSS THE REGION THIS AFTN, AHEAD OF ANOTHER
DISTURBANCE JUST WEST OF THE MS RIVER. THESE AREAS OF CONVECTION ARE
CURRENTLY NOTED ON WATER VAPOR SATELLITE IMAGERY AND RAP H5 ANALYSIS.
BEHIND THE SECOND DISTURBANCE IS A MUCH STRONGER DISTURBANCE/OPEN
UPPER LEVEL WAVE CURRENTLY MEANDERING EASTWARD ACROSS AR/MO. THIS
SYSTEM IS EXPECTED TO REDEVELOP A LARGE CLUSTER OF THUNDERSTORMS
WHICH IS PROGGED TO ARRIVE AROUND OR SLIGHTLY BEFORE 12Z TOMORROW
MORNING.

A FEW STRONG TO SEVERE STORMS ARE POSSIBLE FROM EARLY TOMORROW
THROUGH EARLY AFTERNOON AS THE STRONGEST OF THE PARADE OF DISTURBANCES
PUSHES ACROSS THE AREA. WHILE WIND SHEAR IS NOT IMPRESSIVE WITH THIS
SYSTEM, THERE WILL BE ENOUGH FORCING IN PLACE TO WARRANT A STRONG TO
DAMAGING WIND THREAT. ADD TO THAT AMPLE MOISTURE IN PLACE (WITH
DEWPOINTS IN THE UPPER 60S TO LOWER 70S, PWAT VALUES APPROACHING 150%
OF NORMAL, AND A NEARLY SATURATED VERTICAL PROFILE ON SOUNDINGS), AND
VERY HEAVY RAINFALL IS ALSO EXPECTED. RAIN RATES OF 2-4" PER HOUR
WERE OBSERVED EARLIER TODAY, AND WITH THE STRONGER DISTURBANCE
EXPECTED TOMORROW, AM LEANING TOWARD THE HIGHER RANGE OF THIS. FOR
THIS REASON, "HEAVY RAINFALL" WAS OFFICIALLY ADDED TO THE GRIDS
THROUGH LATE TUESDAY NIGHT. THIS SCENARIO (PLUS TRAINING CELLS) MAY
LEAD TO INSTANCES OF FLASH FLOODING AND POSSIBLY EVEN RIVER/CREEK
FLOODING ACROSS THE AREA TOMORROW. THIS THREAT WILL CONTINUE TO BE
MONITORED AS SOIL MOISTURE CONDITIONS CONTINUE TO MOISTEN WITH EVERY
ROUND OF ADDITIONAL RAINFALL.

OTHERWISE, FOR THE REMAINDER OF THE FORECAST, THE WEAK COLD FRONT
WILL PUSH THROUGH THE AREA FINALLY ENDING THE SHOWER/STORM THREAT
LATE TUESDAY NIGHT. GFS/ECMWF/NAM MODEL OUTPUT SHOWS THIS ABRUPT END
TO THE CONVECTION (ENDING AS SHOWERS LATE ON TUESDAY). WITH THE DRIER
AIR FILTERING INTO THE AREA, MORNING LOWS THURSDAY WILL BOTTOM OUT
IN THE LOWER TO MIDDLE 60S. AN UPPER HIGH WILL STRENGTHEN OVER THE
SOUTHERN PLAINS LATER THIS WEEK, TRANSLATING TO WARM/DRY CONDITIONS
FOR WEDNESDAY AND THURSDAY. MORE UPPER LEVEL DISTURBANCES WILL RIDE
AROUND THE EASTERN PERIPHERY OF THE UPPER RIDGE TO THE WEST, BRINGING
THE CHANCE FOR AT LEAST ISOLATED SHOWERS AND STORMS FRIDAY AND
SATURDAY. THE WEATHER PATTERN WILL FINALLY TRANSITION MORE INTO A
SUMMERTIME REGIME BY EARLY NEXT WEEK, WITH MORE DIURNALLY DRIVEN
CONVECTION DEVELOPING IN THE AFTERNOON AND DISSIPATING WITH SUNSET
EACH EVENING.

12

&&

.AVIATION...
FOR 00Z TAFS... CLUSTER OF SHRA AND TSRA, SOME WITH GUSTY WINDS, FQT
LIGHTNING AND +RA WILL OCCUR IN THE KHSV VCNTY OVER THE NEXT 1-2
HOURS. BRIEF IFR VSBYS AND MVFR CIGS ARE PSBL. NEAR TERM
REDEVELOPMENT OF SHRA AND TSRA AT KMSL IS A BIT LESS CERTAIN THIS
EVENING. OVERNIGHT, A COMPLEX OF TSRA WILL DEVELOP OVER NRN MS AND
WRN TN AND PUSH EASTWARD AS AN UPPER LEVEL DISTURBANCE APPROACHES.
BEST ESTIMATE OF TIMING OF ARRIVAL WILL BE 03-06Z AT KMSL AND 05-08Z
AT KHSV. TEMPORARY MVFR CONDS IN +RA ARE QUITE PSBL AGAIN, AND SOME
IFR CANNOT BE RULED OUT. A COLD FRONT WILL DROP INTO THE AREA LATE
TUESDAY WITH YET ANOTHER ROUND OF POSSIBLE SHRA AND TSRA.

AK

&&

.PREV DISCUSSION...
/ISSUED 403 PM CDT MON JUN 17 2013/
QUITE AN ACTIVE WEATHER DAY CONTINUES ACROSS THE TENNESSEE VALLEY
THIS AFTERNOON AS AN OUTFLOW BOUNDARY FROM REMNANT CONVECTION OVER
CENTRAL MS CONTINUES PUSHING NORTHEASTWARD ACROSS THE CWA. A FEW
STRONG TO SEVERE STORMS OCCURRED, MAINLY WITH A DAMAGING WIND THREAT.
IN ADDITION, VERY HEAVY RAINFALL ALSO ACCOMPANIED THESE STORMS AS
THEY TRAVERSED THE AREA, WITH A FEW INSTANCES OF NUISANCE/FLASH
FLOODING REPORTED. ALL OF THIS ACTIVITY IS IN RESPONSE TO A 500MB
DISTURBANCE PUSHING ACROSS THE REGION THIS AFTN, AHEAD OF ANOTHER
DISTURBANCE JUST WEST OF THE MS RIVER. THESE AREAS OF CONVECTION ARE
CURRENTLY NOTED ON WATER VAPOR SATELLITE IMAGERY AND RAP H5 ANALYSIS.
BEHIND THE SECOND DISTURBANCE IS A MUCH STRONGER DISTURBANCE/OPEN
UPPER LEVEL WAVE CURRENTLY MEANDERING EASTWARD ACROSS AR/MO. THIS
SYSTEM IS EXPECTED TO REDEVELOP A LARGE CLUSTER OF THUNDERSTORMS
WHICH IS PROGGED TO ARRIVE AROUND OR SLIGHTLY BEFORE 12Z TOMORROW
MORNING.

A FEW STRONG TO SEVERE STORMS ARE POSSIBLE FROM EARLY TOMORROW
THROUGH EARLY AFTERNOON AS THE STRONGEST OF THE PARADE OF DISTURBANCES
PUSHES ACROSS THE AREA. WHILE WIND SHEAR IS NOT IMPRESSIVE WITH THIS
SYSTEM, THERE WILL BE ENOUGH FORCING IN PLACE TO WARRANT A STRONG TO
DAMAGING WIND THREAT. ADD TO THAT AMPLE MOISTURE IN PLACE (WITH
DEWPOINTS IN THE UPPER 60S TO LOWER 70S, PWAT VALUES APPROACHING 150%
OF NORMAL, AND A NEARLY SATURATED VERTICAL PROFILE ON SOUNDINGS), AND
VERY HEAVY RAINFALL IS ALSO EXPECTED. RAIN RATES OF 2-4" PER HOUR
WERE OBSERVED EARLIER TODAY, AND WITH THE STRONGER DISTURBANCE
EXPECTED TOMORROW, AM LEANING TOWARD THE HIGHER RANGE OF THIS. FOR
THIS REASON, "HEAVY RAINFALL" WAS OFFICIALLY ADDED TO THE GRIDS
THROUGH LATE TUESDAY NIGHT. THIS SCENARIO (PLUS TRAINING CELLS) MAY
LEAD TO INSTANCES OF FLASH FLOODING AND POSSIBLY EVEN RIVER/CREEK
FLOODING ACROSS THE AREA TOMORROW. THIS THREAT WILL CONTINUE TO BE
MONITORED AS SOIL MOISTURE CONDITIONS CONTINUE TO MOISTEN WITH EVERY
ROUND OF ADDITIONAL RAINFALL.

OTHERWISE, FOR THE REMAINDER OF THE FORECAST, THE WEAK COLD FRONT
WILL PUSH THROUGH THE AREA FINALLY ENDING THE SHOWER/STORM THREAT
LATE TUESDAY NIGHT. GFS/ECMWF/NAM MODEL OUTPUT SHOWS THIS ABRUPT END
TO THE CONVECTION (ENDING AS SHOWERS LATE ON TUESDAY). WITH THE DRIER
AIR FILTERING INTO THE AREA, MORNING LOWS THURSDAY WILL BOTTOM OUT
IN THE LOWER TO MIDDLE 60S. AN UPPER HIGH WILL STRENGTHEN OVER THE
SOUTHERN PLAINS LATER THIS WEEK, TRANSLATING TO WARM/DRY CONDITIONS
FOR WEDNESDAY AND THURSDAY. MORE UPPER LEVEL DISTURBANCES WILL RIDE
AROUND THE EASTERN PERIPHERY OF THE UPPER RIDGE TO THE WEST, BRINGING
THE CHANCE FOR AT LEAST ISOLATED SHOWERS AND STORMS FRIDAY AND
SATURDAY. THE WEATHER PATTERN WILL FINALLY TRANSITION MORE INTO A
SUMMERTIME REGIME BY EARLY NEXT WEEK, WITH MORE DIURNALLY DRIVEN
CONVECTION DEVELOPING IN THE AFTERNOON AND DISSIPATING WITH SUNSET
EACH EVENING.

12

&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
TN...NONE.
&&

$$

FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE
AT WEATHER.GOV/HUNTSVILLE.