Area Forecast Discussion
Issued by NWS Jackson, KY

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000
FXUS63 KJKL 261842
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
242 PM EDT SAT JUL 26 2014

.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 242 PM EDT SAT JUL 26 2014

DYNAMIC SITUATION UNFOLDING OVER THE NEXT 24 TO 36 HOURS AS A DEEP
TROUGH ALOFT DIVES INTO THE OHIO VALLEY. A STRONG COLD FRONT WILL
DROP SOUTHEAST INTO THE REGION SUPPLANTING WHAT WILL BECOME A VERY
WARM AND VERY MOIST AIRMASS IN PLACE ACROSS OUR REGION. THIS
COMBINATION OF A SPRING-TIME SETUP ALOFT COMBINED WITH SUMMER-TIME
HEAT AND HUMIDITY WILL CREATE CONDITIONS FAVORABLE FOR A SIGNIFICANT
SEVERE WEATHER OUTBREAK ON SUNDAY.

MODELS CONTINUE TO INDICATE A THUNDERSTORM COMPLEX WILL ORGANIZE TO
OUR WEST THIS AFTERNOON AND EVENING. THIS APPEARS TO BE HAPPENING
OVER MISSOURI AT THIS TIME. THESE STORMS SHOULD MARCH EASTWARD INTO
THE OVERNIGHT HOURS LIKELY ENDING UP SOMEWHERE OVER SOUTHERN INDIANA
AND NORTHERN KENTUCKY BY OR SHORTLY AFTER MIDNIGHT. THIS COMPLEX
SHOULD BE WEAKENING AS IT ENTERS OUR FORECAST AREA AFTER
MIDNIGHT...BUT CANNOT RULE OUT THE THREAT FOR DAMAGING WINDS AS IT
CROSSES THE REGION. THIS THREAT WOULD BE GREATEST FROM JKL AND
POINTS TO THE NORTH.

THE GREATER SEVERE WEATHER THREAT CONTINUES TO BE THE ANTICIPATED
SECOND ROUND OF THUNDERSTORMS EXPECTED TO ERUPT OVER US OR JUST TO
OUR NORTH SUNDAY AFTERNOON. PROVIDED EARLY MORNING CONVECTION GETS
OUT OF THE WAY IN TIME AND ATMOSPHERE DESTABILIZES AS PROJECTED...
THESE STORMS COULD BE QUITE STRONG. SOUNDINGS TOMORROW AFTERNOON ARE
IMPRESSIVE. STORM RELATIVE HELICITY VALUES EXCEED 300 M2/S2 COMBINED
WITH CAPE PROGGED TO EXCEED 3000 J/KG AND LCLS AROUND 3000 FT MSL.
IF THESE CONDITIONS VERIFY...A RARE JULY TORNADO OUTBREAK COULD
OCCUR. STILL...LOTS OF UNCERTAINTY WITH HOW TONIGHTS ACTIVITY WILL
PAN OUT AND HOW THIS WILL AFFECT OUR CONDITIONS ON SUNDAY BUT WILL
CONTINUE TO PLAY UP THE SEVERE WEATHER POTENTIAL IN OUR SUITE OF
PRODUCTS.

IN ADDITION TO THE SEVERE WEATHER CONCERNS...ISOLATED FLASH FLOODING
IS A CONCERN PRIMARILY ON SUNDAY. MOISTURE POOLING IN ADVANCE OF THE
FRONT WILL PUSH SURFACE DEWPOINTS INTO THE LOW TO MID 70S AND PWATS
WILL JUMP TO 1.75 INCHES AND ABOVE. STORM MOTIONS LOOK FAST ENOUGH
TO PRECLUDE A WIDESPREAD FLASH FLOODING THREAT...BUT AGAIN THAT WILL
DEPEND LARGELY ON HOW PRIMED WE GET BY TONIGHTS CONVECTION. NO FLASH
FLOOD WATCH WILL BE ISSUED AT THIS TIME...BUT THAT MAY NEED TO BE
REVISITED SHOULD THE INITIAL ROUND OF CONVECTION SATURATE THE GROUND
TONIGHT.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 242 PM EDT SAT JUL 26 2014

AN ANOMALOUS LARGE AND DEEP UPPER TROUGH WILL PERSIST OVER THE
EASTERN CONUS THROUGH THE PERIOD. THE SURFACE COLD FRONT MARKING THE
LEADING EDGE OF THE UNSEASONABLY COOL AIR MASS UNDER THE TROUGH WILL
BE WELL TO OUR SOUTHEAST ALREADY AS THE PERIOD STARTS...BUT RESIDUAL
LOW LEVEL MOISTURE WILL STILL BE MIXING VERTICALLY INTO THE NEW AIR
MASS AS COOLING ALOFT OCCURS. THIS MAY RESULT IN A FEW SHOWERS OR
THUNDERSTORMS MONDAY AFTERNOON OR EVENING...ESPECIALLY IN OUR NE
COUNTIES WHERE COOLER MID LEVEL TEMPS ARE EXPECTED.

ON TUESDAY...DRIER SURFACE AIR AND A MID LEVEL CAP SHOULD KEEP
CONVECTIVE CURRENTS BELOW ABOUT 10K FEET. SOME LIQUID COULD STILL
TRY TO FALL OUT OF THE CLOUDS...BUT WITH LIMITED CLOUD DEPTH AND
DRIER AIR...WILL ONLY MENTION SPRINKLES IN THE FORECAST.

A COOL AND DRY AIR MASS FIRMLY IN PLACE...COUPLED WITH A CESSATION OF
COOLING ALOFT...WILL ALLOW FOR MAINLY CLEAR SKIES FROM TUESDAY NIGHT
THROUGH THURSDAY NIGHT. NEAR RECORD LOW TEMPS WILL BE A POSSIBILITY.

AS THE HIGHLY AMPLIFIED UPPER TROUGH WEAKENS AT THE END OF THE
WEEK...MODELS AGREE ON ITS AXIS RETROGRADING TO THE WEST AS A LOW
CLOSES OFF. WITH THE LOW/TROUGH AXIS SLIPPING TO OUR WEST...WE WILL
RETURN TO ITS EAST SIDE WHICH IS SYNOPTICALLY MORE FAVORABLE FOR
PRECIP. FLOW FROM THE GULF OF MEXICO WILL STILL BE CUT OFF AND LOW
LEVEL MOISTURE WILL BE SLOW TO INCREASE...SO WILL ONLY USE LOW POPS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 146 PM EDT SAT JUL 26 2014

VFR CONDITIONS ARE ANTICIPATED THROUGH THE FIRST HALF OF THE TAF
PERIOD WITH LIGHT WINDS.

AFTER MIDNIGHT TONIGHT...A COMPLEX OF THUNDERSTORMS WILL LIKELY PUSH
EASTWARD TOWARD THE AREA FROM THE WEST. DETAILS ARE STILL
UNCERTAIN...BUT THE GREATEST THREAT FOR A DIRECT IMPACT FROM THESE
STORMS LIES FROM JKL...SJS AND POINTS TO THE NORTH WHERE A PERIOD OF
AT LEAST MVFR CONDITIONS ARE LIKELY BETWEEN 07Z AND 11Z. THERE IS A
SLIGHT RISK THAT THESE STORMS WILL BE SEVERE CONTAINING DAMAGING
WIND GUSTS. TO THE SOUTH...THERE IS A SMALLER THREAT FOR A DIRECT
IMPACT AND WILL SIMPLY ADVERTISE A GENERIC VCTS MENTION IN THE TAFS
FOR LOZ AND SME. ONCE THE FIRST ROUND OF THUNDERSTORMS PASSES
THROUGH...THERE WILL LIKELY BE A LULL IN THE SHOWER AND THUNDERSTORM
ACTIVITY BEFORE ANOTHER ROUND MOVES THROUGH SUNDAY AFTERNOON AND
EVENING. THIS SECOND ROUND WILL CARRY A GREATER RISK OF SEVERE
WEATHER.

SOUTHWEST WINDS WILL INCREASE ALOFT THROUGH THE NIGHT...BUT REMAIN
BELOW LLWS THRESHOLDS. THESE WINDS WILL SURFACE DURING THE DAY ON
SUNDAY WITH GUSTS UP TO 20 KTS LIKELY AFTER 15Z.


&&

.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...ABE
LONG TERM...HAL
AVIATION...ABE




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