Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 021042
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
642 AM EDT THU JUL 2 2015

.UPDATE...
ISSUED AT 642 AM EDT THU JUL 2 2015

A DECENT RAIN SHIELD IS CURRENTLY MOVING INTO THE WESTERN PORTION
OF THE CWA. UPDATED POPS TO BETTER REFLECT ONGOING CONDITIONS AND
LIKELY TRENDS THROUGH THE MORNING HOURS. THIS WILL INCLUDE
WIDESPREAD RAIN ACROSS MUCH OF THE SOUTHWESTERN CWA...WHICH HAS
ALREADY RECEIVED A LARGE AMOUNT OF RAIN OVER THE LAST COUPLE DAYS.
GIVEN THE ALREADY SATURATED SOILS...AND ONE HOUR FLASH FLOOD
GUIDANCE AN INCH OR LESS IN SOME LOCATIONS...WENT AHEAD AND
ISSUED AN HOUR URBAN AND SMALL STREAM ADVISORY FOR ANY RAINS THAT
IMPACT THIS AREA OVER THE NEXT FEW HOURS. LUCKILY...IT SEEMS AS
THOUGH THIS FIRST LINE OF SHOWERS IS WEAKENING AS IT MOVES INTO
THE AREA...BUT EXPECT THEM TO START INTENSIFYING AS THE SUN STARTS
WARMING THINGS UP THIS MORNING. ALSO UPDATED THE NEAR-TERM
FORECAST FOR TEMPS...DEW POINTS...AND WINDS WITH THE LATEST
OBSERVATIONAL DATA.

&&

.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 323 AM EDT THU JUL 2 2015

AS OF 3 AM...LINGERING EVENING CONVECTION OVER THE CWA IS CONTINUING
TO DISSIPATE AS BEST ENERGY TURNS ITS ATTENTION TO THE MCS STILL
OVER MISSOURI...WHICH IS NOW GENERATING SCATTERED SHOWERS AND
THUNDERSTORMS OUT AHEAD OF IT. THESE SHOWERS AND THUNDERSTORMS ARE
CURRENTLY MAKING IT INTO WESTERN AND CENTRAL KY/TN AND WILL
LIKELY MAKE IT INTO OUR SOUTHERN CWA OVER THE NEXT HOUR OR SO.
GIVEN THE HIGH AMOUNT OF RAIN THIS AREA OF OUR CWA HAS SEEN OVER
THE LAST COUPLE OF DAYS...AND THE VERY LOW FFG AS OF 0Z
7/02...EXPECT THAT FLOODING CONCERNS WILL LIKELY START ARISING IN
THIS AREA JUST BEFORE DAWN AND CONTINUE THROUGH THE MORNING...AND
EVEN THROUGH MUCH OF THE DAY. AN UPPER LEVEL SHORTWAVE WILL
CONTINUE TO SHIFT ESE TODAY...PULLING THE MCS WITH IT. EXPECT THE
HEART OF THE MCS TO BE OVER WESTERN KY AND SOUTHERN IL BY 12Z
TODAY...WITH A COLD POOL DRIVEN OUTFLOW PULLING HEIGHTENED CHANCES
FOR SHOWERS AND THUNDERSTORMS INTO EASTERN KY. THE MCS WILL
CONTINUE TO SHIFT ACROSS THE STATE THROUGH THE DAY FOLLOWING AN
SHORTWAVE AS IT ROUNDS AN UPPER LEVEL LONGWAVE TROUGH. AS IT
SHIFTS EASTWARD...IT WILL BECOME MORE COLD POOL DRIVEN ONCE MORE
WITH MULTIPLE OUTFLOWS LIKELY CREATING THEIR OWN MEANS FOR
MULTIPLE AREAS OF CONVECTION.

DESPITE WIDESPREAD HEAVY RAIN THROUGH THE DAY AND INTO THE
OVERNIGHT HOURS...WPC AND OTHER MODELS ARE STILL PEGGING THE
SOUTHERN HALF OF THE CWA WITH THE HIGHEST QPF AMOUNTS. AS
MENTIONED ABOVE...THIS IS THE SAME AREA THAT HAS ALREADY BEEN HARD
HIT...SO EXPECT AN ACTIVE DAY AND OVERNIGHT PERIOD AS ANY RAIN
THAT OCCURS WILL LIKELY RESULT IN RUNOFF. WILL KEEP WITH CURRENT
FF WATCH...AS THIS SEEMS TO LINE UP WELL WITH LATEST GUIDANCE AND
WPC QPF FORECAST.

THERE IS SOME DISCREPANCIES IN THE ECMWF AND THE NAM12 LATE TONIGHT
AS THE MCS REACHES THE FAR EASTERN EXTENT OF THE CWA. THE NAM SHOWS A
BROADER SURFACE LOW PRESSURE SYSTEM FORMING AND KEEPS MULTIPLE
HEAVIER WAVES OF PRECIP OVER SOUTHERN AND EASTERN KY THROUGH 12Z
FRIDAY. MEANWHILE...THE ECMWF HAS A SLIGHTLY WEAKER BUT MORE
CENTRALIZED LOW...AND PULLS MOST OF THE MOISTURE OUT OF THE STATE
WITH THE EXCEPTION OF FAR EASTERN KY BY THIS SAME TIME.
REGARDLESS...EXPECT THERE WILL BE SOME DEGREE OF RAIN POTENTIAL
CENTERED OVER OUR CWA...WHICH WARRANTED KEEPING LIKELY AND ABOVE
POPS ACROSS MUCH OF THE CWA THROUGH THE NIGHT.

FOR FRIDAY...ANY LINGERING MOISTURE ACROSS THE STATE WILL LIKELY
RESULT IN A RESPARKING OF SCT TO NUMEROUS SHOWERS AND THUNDERSTORMS
DURING THE DAYTIME HOURS DUE TO PEAK HEATING AND INTERACTION WITH A
STALLED FRONTAL BOUNDARY PASSING THROUGH THE STATE /ATTACHED TO
THE DEPARTING LOW/. WHILE CONVECTION WILL GENERALLY BE IN AND
AROUND THE AREA OF THE BOUNDARY...EXPECT COVERAGE TO INCLUDE A
WIDE AREA ACROSS MOST OF THE STATE AND AREAS SE. ONE THING TO
NOTE...HOWEVER...IS THAT MODEL SOUNDINGS ARE SHOWING A LARGE
INFLUX OF DRY AIR IN THE MID AND UPPER LEVELS AFTER THE
SHORTWAVE/MCS/AND SURFACE LOW PASS THROUGH. THIS WILL KEEP MOST
MOISTURE CONFINED TO A SHALLOW LLVL LAYER. LATEST NAM12 FORECAST
SOUNDINGS ARE ALSO SHOWING AN INVERSION AT ALL TAF SITES JUST
ABOVE THIS MOIST LAYER. WITH THIS IN MIND...EXPECT STRONG TO
SEVERE STORM POTENTIAL TO BE VERY LIMITED WITH THIS INVERSION IN
PLACE...AND ANY SHOWERS TO BE MUCH LIGHTER IN NATURE WITH LOWER
QPF VALUES. THIS CORRELATES WELL WITH THE END OF THE WATCH PERIOD
AS WELL.

.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 455 AM EDT THU JUL 2 2015

AN WAVERING FRONTAL BOUNDARY IS EXPECTED TO SINK SLOWLY SOUTHWARD
FROM THE REGION DURING THE PERIOD. ITS PROXIMITY WILL SUPPORT A
CONTINUING POSSIBILITY OF SHOWERS AND THUNDERSTORMS. HOWEVER...
ENOUGH DRIER AIR MAY MAKE IT INTO THE REGION TO LOWER THE POP
SUNDAY THROUGH MONDAY...BEFORE ANOTHER WEAKENING COLD FRONT MOVING
IN FROM THE NORTHWEST BRINGS AN INCREASE IN THE POP TUESDAY AND
WEDNESDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 142 AM EDT THU JUL 2 2015

WHILE MOST SHOWERS AND THUNDERSTORMS HAVE DISSIPATED ACROSS
EASTERN KY...ANOTHER AREA OF HEAVY RAIN AND THUNDERSTORMS
ASSOCIATED WITH A MCS JUST MOVING INTO THE MISSISSIPPI RIVER
VALLEY IS MAKING ITS WAY ACROSS CENTRAL KY AND TN...AND SHOULD
BEGIN IMPACTING THE EASTERN PORTION OF THE STATE OVER THE NEXT FEW
HOURS. WENT AHEAD AND KEPT MENTION OF VCSH THROUGH THE REST OF THE
NIGHT...THOUGH MAY NEED TO UPDATE TAF IF ANY ONE LOCATION IS
EXPECTED TO SEE RAIN FOR A PROLONGED PERIOD OF TIME. DESPITE LOW
CLOUD COVER /GENERALLY IFR/...THERE IS ENOUGH MOISTURE THAT FOG IS
STILL POPPING UP AT TAF SITES AS WELL. UNFORTUNATELY...THE VIS
WILL LIKELY FLUCTUATE THROUGHOUT THE NIGHT UNDER A TRUE PATCHY
DENSE FOG ENVIRONMENT...SO TRIED TO GEAR TAF TOWARD WORST
CONDITIONS EXPECTED. AS THE MCS CONTINUES TO APPROACH FROM THE
WEST...EXPECT NUMEROUS SHOWERS AND THUNDERSTORMS BY DAYBREAK AND
THROUGH THE DAY TOMORROW. VIS AND CIGS WILL LIKELY BE DEPENDENT ON
ANY PASSING STORMS...BUT GENERAL CONDITIONS SHOULD LIE SOMEWHERE
BETWEEN IFR AND MVFR DUE TO THE LOW CLOUD DECK EXPECTED TO BE IN
PLACE. BY TOMORROW NIGHT...ANY RESIDUAL MOISTURE WILL LIKELY LEAD
TO FOG ONCE MORE...DESPITE LINGERING LOW CIGS AND SHOWERS. OUTSIDE
OF ANY STORMS...WINDS WILL BE LIGHT THROUGH THE PERIOD...AT AROUND
5 KTS OR LESS OVERNIGHT AND 10 KNOTS OR LESS DURING THE DAY...AND
GENERALLY FROM THE SOUTHWEST.


&&

.JKL WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH THROUGH FRIDAY MORNING FOR KYZ068-069-079-080-
083>088-114>118.

&&

$$

UPDATE...JMW
SHORT TERM...JMW
LONG TERM...HAL
AVIATION...JMW


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