Area Forecast Discussion
Issued by NWS Jackson, KY

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000
FXUS63 KJKL 291926
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
326 PM EDT SUN MAR 29 2015

.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 325 PM EDT SUN MAR 29 2015

HIGH PRESSURE IS NOW SHIFTING SE OF THE REGION...WITH THE CENTER
NEARING THE ATLANTIC COAST. AS THIS HIGH CONTINUES TO DEPART...DRY
AIR WILL CONTINUE TO HOLD ON THOUGH WINDS HAVE SHIFTED TO A MORE
SRLY DIRECTION ALLOWING FOR SLIGHTLY WARMER TEMPS TO BEGIN ADVECTING
IN. DEW POINTS WILL SLOWLY RESPOND...BUT CRITICAL RH VALUES IN THE
MID TEENS IN SOME LOCATIONS...WILL LIKELY CONTINUE FOR A FEW MORE
HOURS. BY LATE THIS AFTERNOON AND INTO THIS EVENING...AN UPPER LEVEL
SHORTWAVE WILL MOVE EAST ACROSS THE UPPER MISSISSIPPI RIVER
VALLEY...PULLING A COLD FRONTAL BOUNDARY ACROSS THE STATE. EXPECT
THIS COLD FRONT TO TRAVERSE EASTERN KY BETWEEN 6 AND 12Z TONIGHT.

AS THIS FRONTAL BOUNDARY APPROACHES...HIGHER DEW POINTS WILL SLOWLY
WORK IN...AS WILL UPPER LEVEL CLOUDS. HOWEVER...STILL IN THE MINDSET
THAT THE AMOUNT OF DRY AIR IN THE BOUNDARY LAYER ACROSS THE AREA
WILL BE HARD TO OVERCOME AS THE PRECIP MAKES IT INTO THE AREA.
DESPITE MODELS PAINTING A LARGE AREA OF QPF OVER THE CWA QUICKLY
...EXPECT THINGS TO BE SLOW TO START UP...BEFORE FILLING IN AROUND
6Z AND AFTER. EVEN THEN...WHILE POP COVERAGE WILL BE LIKELY TO
DEFINITE...QPF WILL REMAIN LIGHT. STILL EXPECTING ONLY BETWEEN 0.1
AND 0.2 INCHES OF RAIN THROUGH MONDAY MORNING. ONCE THE UPPER LEVEL
SHORTWAVE AND COLD FRONT EXIT THE REGION AFTER 12Z...ANOTHER BURST
OF DRY NW AIR WILL PULL INTO THE REGION AND DRY THINGS BACK OUT
AGAIN. FORTUNATELY...CONSIDERING THAT THE ORIGIN OF THE AIR MASS
BEHIND THIS FRONT IS PACIFIC IN NATURE...TEMPERATURES WILL TURN OUT
TO BE WARMER BEHIND THE SYSTEM THAN AHEAD. STAYED FAIRLY CLOSE TO
THE BLEND OF MODEL SOLUTIONS AND GUIDANCE FOR POPS AND TEMPS.

WITH A WARMER HIGH PRESSURE AIRMASS IN PLACE...AND WINDS SHIFTING TO
A MORE SRLY DIRECTION OVERNIGHT...EXPECT TEMPERATURES TO CONTINUE TO
BE MILD DURING THE OVERNIGHT HOURS MONDAY NIGHT INTO TUESDAY
MORNING. ONLY EXPECTING A FEW DEGREES LOWER THAN TEMPS TONIGHT
...GENERALLY IN THE UPPER 30S. MORE SEASONABLE TEMPERATURES WILL
FINALLY MAKE IT BACK INTO THE REGION AS WE HEAD INTO TUESDAY.

.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)
ISSUED AT 440 AM EDT SUN MAR 29 2015

THE RECENT GFS AND ECMWF RUNS ARE GENERALLY GOOD AGREEMENT TROUGH
THE PERIOD. THE PERIOD IS EXPECTED TO BEGIN WITH A WESTERN US RIDGE
EXTENDING NORTH INTO THE CANADIAN ROCKIES AND EASTERN AK...WITH A
TROUGH FROM THE PLAINS INTO EASTERN CANADA AND THE EASTERN US.
THE AXIS OF THIS TROUGH IS EXPECTED TO EXTEND FROM NORTHERN CANADA
SOUTH INTO THE NORTHEASTERN STATES AND THEN SOUTH TO THE EAST OF
FL. AN UPPER LEVEL LOW IS PROJECTED TO BE TO THE WEST OF THE BAJA
OF CALIFORNIA AT THAT TIME AS WILL A TROUGH EXTENDING FROM THE
GULF OF AK SOUTH ACROSS PORTIONS OF THE EASTERN PACIFIC TO THE
WEST OF THE US AND CANADIAN COAST.

AS THE WEEK PROGRESSES THE PATTERN WILL HAVE A ZONAL FLAVOR WITH THE
TROUGH OVER EASTERN CANADA AND NORTHEASTERN STATES BECOMING MORE
BROAD AND THE RIDGE INITIALLY OVER THE WEST COAST SHIFTING TO THE
PLAINS BY MIDWEEK. MEANWHILE...THE TROUGH INITIALLY WEST OF THE BAJA
OF CALIFORNIA IS EXPECTED TO GET KICKED INTO THE SOUTHERN PLAINS
BY THE TROUGH WORKING INTO THE WESTERN US. THIS BY WED
EVENING...THE 0Z GFS AND 0Z CONSENSUS IS FOR RIDGE AXIS TO HAVE
MOVED TO THE LOWER OH VALLEY TO GREAT LAKES WITH SOME MODEL
VARIABILITY WITH THE SHORTWAVE MOVING FROM THE SOUTHERN PLAINS
INTO THE MS VALLEY REGION. AT THAT POINT...HEIGHTS ARE EXPECTED TO
BE FALLING OVER THE PLAINS REGION. WED NIGHT INTO THU...THE
SHORTWAVE RIDGE AXIS IS PROJECTED TO HAVE SHIFTED FURTHER EAST AND
NORTHEAST FROM THE MID ATLANTIC STATES NORTH INTO ONTARIO AND
QUEBEC WITH UNCERTAINTY INCREASING IN THE STRENGTH OF THE TROUGH
MOVING AT THAT POINT FROM THE PLAINS TOWARD THE MS VALLEY REGION
AND WESTERN GREAT LAKES. THE MODEL CONSENSUS FROM THE 0Z GFS AND
0Z ECMWF IS FOR THE SHORTWAVE TROUGH TO GENERALLY PASS SOUTH OF
EASTERN KY ACROSS THE SOUTHEASTERN STATES...BUT UPPER LEVEL FLOW
BECOMING MORE WESTERLY TO SOUTHWESTERLY BY LATE THU INTO THU NIGHT
AS THE 500 MB TROUGH APPROACHES LEADING TO A WARMER AND MORE MOIST
AIR MASS MOVING IN. THE CONSENSUS IS ALSO FOR THE TROUGH TO MOVE
FURTHER EAST INTO ONTARIO AND QUEBEC AS WELL AS THE GREAT LAKES
AND NEAR THE OH VALLEY REGION BY THE END OF THE PERIOD. JUST
BEYOND THE PERIOD...A RIDGE IS EXPECTED ACROSS THE ROCKIES WITH
EASTERN CANADIAN TO EASTERN CONUS TROUGHING.

THIS PATTERN WILL BRING AT LEAST SOMEWHAT CHANGEABLE WEATHER DUE TO
THE QUASI ZONAL PATTERN. EARLY IN THE PERIOD...WEAK SFC HIGH
PRESSURE IS EXPECTED TO BE CENTERED OVER THE MIDDLE TN TO CENTRAL KY
REGION...WHICH MOVES INTO THE SOUTHEASTERN STATES ON MON NIGHT INTO
TUE. MEANWHILE A NORTHERN STREAM COLD FRONT SHOULD DROP SOUTH OF THE
GREAT LAKES AND INTO THE OH VALLEY REGION.ON TUE INTO TUE
NIGHT...BUT BE RATHER MOISTURE STARVED AT THAT POINT WITH HIGH
PRESSURE OVER THE GREAT LAKES AND NORTHEAST NOSING INTO THE AREA FOR
A TIME. MEANWHILE...AS A LOW PRESSURE SYSTEM DEVELOPS AND TRACKS
RATHER QUICKLY NEAR THE US CANADIAN BORDER TO JUST NORTH OF LAKE
SUPERIOR FROM WED INTO WED NIGHT...A WARM FRONT SHOULD LIFT NORTH
ACROSS EASTERN KY. THIS WILL PUT THE REGION IN THE WARM SECTOR FOR
THU INTO FRI...WITH ANTHER WAVE DEVELOPING ALONG THE FRONT AND
TRACKING FROM THE PLAINS TO MID MS VALLEY REGION THU INTO EARLY
FRIDAY AND THEN FURTHER NORTHEAST WHICH MAY SLOW DOWN THE EASTWARD
PROGRESS OF THE COLD FRONT ASSOCIATED AS THE TROUGH GRADUALLY MOVES
INTO THE EASTERN CONUS AROUND THE END OF THE PERIOD. DURING THIS
PERIOD...FROM LATE WED NIGHT INTO SATURDAY THERE WILL BE A CHANCE
FOR SHOWERS. THE CHANCES WILL BE HIGHEST FROM THURSDAY NIGHT INTO
FRIDAY NIGHT. MODEL GUIDANCE SUGGESTS THERE COULD BE TWO PERIODS
WHERE PRECIPITATION CHANCES POSSIBLY MAX OUT...FROM THU NIGHT INTO
EARLY ON FRIDAY AND THEN LATE FRIDAY INTO FRIDAY EVENING. THE FIRST
ROUND WOULD BE WITH SOME INSENTROPIC LIFT AND POSSIBLY SOME JET
INTERACTION AND THE SECOND ROUND NEAR AND AFTER THE COLD FRONTAL
PASSAGE AND POSSIBLE INTERACTION WITH SOME UPPER JET DYNAMICS.
MOISTURE INCREASES SUCH THAT THUNDER HAS BEEN INCLUDED FROM THURSDAY
INTO FRIDAY...BUT CHANCES ARE PROBABLY BEST THU NIGHT AS WINDS
THROUGH THE COLUMN INCREASE AND WITH PW INCREASING SOME GOOD RAINERS
AND POSSIBLY A STRONG STORM OR TWO. CHANCES MAY ALSO PEAK AT SOME
POINT ON FRIDAY...PENDING THE TIMING OF THE FRONTAL PASSAGE.

THERE SHOULD BE A GRADUAL MODERATING TREND FROM TUE INTO THU OR FRI
AS 850 MB TEMPS CLIMB FROM NOT FAR FROM 0C AT PRESENT TO 10 TO 12C
BY THU INTO FRIDAY. A DROP IN 850 MB TEMPS SHOULD DROP AS THE TROUGH
MOVES IN LATE NEXT WEEK WITH THE CURRENT MODEL CONSENSUS ONLY DOWN
TO AROUND -5C...BUT THERE IS UNCERTAINTY AND TIME WILL TELL.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 149 PM EDT SUN MAR 29 2015

HIGH PRESSURE IS CURRENTLY EXITING TO THE SE OF THE REGION...WITH
RETURN FLOW HAVING SHIFTED WINDS TO A MORE SRLY DIRECTION
GENERALLY LESS THAN 10 KNOTS. DEW POINTS WILL REMAIN QUITE LOW
THROUGH THE DAY...WITH MOSTLY CLEAR SKIES EXPECTED...AND THE
POTENTIAL FOR A FEW GUSTS IN THE 15KT RANGE. BY LATE THIS
AFTERNOON/EVENING...A COLD FRONT WILL APPROACH KY FROM THE
WEST...BRINGING AN INCREASE IN CLOUD COVER ACROSS EASTERN KY FROM
NW TO SE. LATEST FORECAST SOUNDINGS ARE SHOWING A QUICK DECREASE
IN CIGS FROM VFR TO MVFR BETWEEN 0 AND 2Z THIS EVENING...AND
POTENTIALLY DOWN TO IFR AS THE RAIN SETS IN OVERNIGHT. RAIN SHOULD
BE QUITE LIGHT IN NATURE...WITH LITTLE EXPECTED IN THE WAY OF VIS
RESTRICTIONS /GENERALLY MVFR OR HIGHER/...THOUGH SOME FOG MAY
DEVELOP AND LINGER INTO THE MORNING HOURS. EXPECT CIGS TO SLOWLY
MIX BACK OUT TO VFR AFTER 12Z TOMORROW.


&&

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

$$

SHORT TERM...JMW
LONG TERM...JP
AVIATION...JMW


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