Area Forecast Discussion
Issued by NWS Jackson, KY

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000
FXUS63 KJKL 021214
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
714 AM EST MON MAR 2 2015

.UPDATE...
ISSUED AT 658 AM EST MON MAR 2 2015

UPDATED THE HOURLY GRIDS THROUGH 14Z THIS MORNING TO ADD IN SOME
PATCHY DRIZZLE. THE PRECIPITATION HAS BEEN A BIT SLOWER TO EXIT
THE AREA THAN THE FORECAST HAD BEEN CALLING FOR...SO THE UPDATE
WAS NECESSARY. ALSO...THERE HAVE BEEN A FEW REPORTS OF A LIGHT
GLAZE OF ICE ON CARS AND OTHER ELEVATED SURFACES AROUND THE
AREA...INCLUDING SOME AREA ROADS. SLICK ROADS WILL BE A
POSSIBILITY FOR AREAS THE RECEIVED RAIN OVERNIGHT AND THAT ARE
BELOW FREEZING. TEMPERATURES SHOULD BE WARM ENOUGH BY 9 OR 10 AM
FOR ANY SLICKS ON AREAS TO HAVE MELTED AND CLEARED UP.

&&

.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 305 AM EST MON MAR 2 2015

AN AREA OF LIGHT RAIN SHOWERS WILL CONTINUE TO MOVE ACROSS THE
AREA EARLY THIS MORNING ALONG AN EASTWARD ADVANCING COLD FRONT.
THE FRONT IS EXPECTED TO MOVE FAIRLY SLOWLY...SO THE RAIN
ACCOMPANYING IT IS FORECAST TO LAST THROUGH 11 OR 12Z THIS
MORNING. AREAS OF FOG WILL CONTINUE BE AN ISSUE THROUGH EARLY
THIS MORNING AS WELL. THE PRECIP AND FOG SHOULD BE GONE BY BETWEEN
12 AND 13Z. ONCE THE FRONT HAS MOVED OFF WELL TO OUR
EAST...EASTERN KENTUCKY SHOULD REMAIN PRECIPITATION THROUGH LATE
THIS EVENING. OUR NEXT ROUND OF ACTIVE WEATHER WILL BEGIN TO
AFFECT THE AREA LATE MONDAY NIGHT INTO TUESDAY AS A WEAK IMPULSE
THAT IS FORECAST TO MOVE OUT OF THE SOUTHERN PLAINS...PHASES WITH
A LARGE SCALE UPPER TROUGH THAT IS EXPECTED TO MOVE OUT OF THE
CENTRAL ROCKYS AND ACROSS THE NORTHERN PLAINS AND GREAT LAKES
REGION. THE SOUTHERN SYSTEM WILL EVENTUALLY MORPH INTO A WARM
FRONT AS IT BEGINS TO MERGE WITH THE NORTHERN SYSTEM. AS THIS
BOUNDARY MOVES NORTH ACROSS CENTRAL AND EASTERN KENTUCKY...LIGHT
RAIN IS EXPECTED TO BREAK OUT ALONG IT. AT THE ONSET OF THE
EVENT...WARM MOIST AIR ALOFT WILL PUSH ACROSS AND NORTH OF THE
FRONT...OVERRIDING COLD AIR AT THE SURFACE. FREEZING
RAIN...SLEET...AND PERHAPS EVEN SOME SNOW WILL BE POSSIBLE AS THE
RAIN FALLS INTO THE COLD AIR BELOW. THE GOOD NEWS IS THAT THE WARM
FRONT SHOULD MOVE THROUGH THE AREA QUICKLY ENOUGH TO PREVENT ANY
SIGNIFICANT ICE ACCUMULATIONS FROM OCCURRING. THE WARM FRONT IS
THEN PROGGED TO STALL JUST TO OUR NORTH. AFTER THIS HAPPENS...A
WAVE OF LOW PRESSURE WILL FORM ALONG THE BOUNDARY AND BEGIN
PUSHING THE BOUNDARY EASTWARD. THIS WILL ALLOW COLD AIR FROM THE
NORTHERN AND CENTRAL PLAINS TO ALSO BEGIN PUSHING
EAST...TRANSFORMING THE BOUNDARY INTO A POTENT COLD FRONT.
WIDESPREAD RAIN WILL ACCOMPANY THE COLD FRONT AS IT MOVES SLOWLY
EAST ACROSS THE OHIO AND TENNESSEE VALLEYS. THE RAIN COULD BE
HEAVY AT TIMES AND COULD LEAD TO FLOODING PROBLEMS ACROSS THE
AREA. AREAS PARTICULARLY PRONE TO FLOODING WILL BE THE
KENTUCKY...CUMBERLAND...AND BIG SANDY RIVER BASINS...WHOSE
HEADWATER AREAS STILL HAVE A GOOD DEAL OF SNOW COVER IN PLACE.
ENOUGH SNOW HAS ALREADY MELTED ACROSS EASTERN KENTUCKY TO CAUSE
THE GROUND TO BE COMPLETELY SATURATED. ANY ADDITIONAL RAINFALL
THAT OCCURS OVER THE NEXT FEW DAYS WILL RUNOFF ALMOST IMMEDIATELY
INTO AREA CREEKS...STREAMS...AND RIVERS. THIS SITUATION WILL NEED
TO MONITORED CLOSELY.

TEMPERATURES DURING THE SHORT TERM WILL START OUT QUITE A BIT
BELOW NORMAL...WITH TODAYS HIGHS EXPECTED TO TOP OUT IN THE LOW TO
MID 40S ACROSS THE AREA. TONIGHTS TEMPERATURES WILL NOT COOL OFF
NEARLY AS MUCH AS WE HAVE SEEN THE PAST SEVERAL NIGHTS...AS WINDS
WILL EVENTUALLY SHIFT THE SOUTHEAST...LEADING TO DOWNSLOPE WARMING
IN OUR EAST AND ALLOWING FOR WARM AIR ADVECTION AT THE SURFACE.
THE MAIN PUSH OF WARM AIR IS EXPECTED TO TAKE PLACE DURING THE DAY
ON TUESDAY...AS WINDS SHIFT TO THE SOUTH AND BEGIN ADVECTING WARM
AIR DIRECTLY OFF THE GULF OF MEXICO INTO THE REGION. HIGHS ON
TUESDAY COULD EASILY MAX OUT IN THE MID TO UPPER 50S AREA WIDE.

.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 430 AM EST MON MAR 2 2015

THE EXTENDED FORECAST PERIOD BEGINS ON TUESDAY NIGHT WITH A
RATHER ACTIVE AND HIGH AMPLITUDE PATTERN IN PLACE. UNDERWAY AND
ALREADY IMPACTING THE OH VALLEY AT THIS TIME FRAME IS AN
ENLONGATED LONGWAVE TROUGH OVER THE CENTRAL CONUS WITH THE TROUGH
AXIS EXTENDING SOUTHWEST INTO THE FOUR CORNERS REGION WHERE A
CLOSED LOW LIES ENTRENCHED OVER THE BAJA REGION. DURING THIS
TIME...A STRONG AN ACTIVE JET CORE EXTENDS FROM OVER THE SOUTHWEST
TO THE GREAT LAKES REGION WITH THE HIGHEST SPEEDS WITH THE JET MAX
OVER THE WESTERN GREAT LAKES OF 140 TO 160 KNOTS. HEADING INTO THE
DAY ON WEDNESDAY...THE MENTIONED LOW OVER THE BAJA EJECTS INTO THE
SOUTHERN PLAINS WHILE THE ENLONGATED TROUGH MOVES THROUGH THE
CENTRAL CONUS. THE DEVELOPED LIFT AND DYNAMICS OVER THE MS VALLEY
AND INTO THE OH VALLEY IS QUITE SUBSTANTIAL AT THIS TIME AS THE
MID AND UPPER LEVEL FLOW TAKE A SOUTHWEST TO NORTHEAST TRAJECTORY.
THIS SETS THE STAGE FOR PRETTY EFFICIENT RAINFALL AT ONSET OF THE
FIRST SYSTEM INTO TUESDAY NIGHT AND THROUGH THE DAY ON WEDNESDAY
AND THEN ANOTHER POSSIBLE WINTER STORM LIKE EVENT INTO MID WEEK.
THIS UNFORTUNATELY EXACERBATES THE CONCERN FOR FLOODING IN
CONJUNCTION WITH THE SNOWMELT AND POSSIBLY EVEN MORE SNOW ON TOP
OF THAT.

CONCERNING THE LOWER LEVELS...HIGH PRESSURE CENTERED JUST OFF
SHORE IN THE ATLANTIC NUDGING INTO THE SOUTHERN PORTIONS OF THE
SOUTHEASTERN CONUS THROUGH THE MID WEEK WILL KEEP A NEARLY STALLED
SOUTHWEST TO NORTHEAST ORIENTATION OF A SURPRISINGLY STRONG
GRADIENT SURFACE COLD FRONT. THE DEVELOPMENT OF SEVERAL WAVES IN
THE MID LEVELS ALONG THIS FRONT TUESDAY NIGHT INTO WEDNESDAY AND
THROUGH THURSDAY WILL KEEP A SIGNIFICANT QPF OVER THE AREA. THIS
WILL ONCE AGAIN KEEP FLOODING A THREAT WITH THE AMOUNT OF PRECIP
EXPECTED. AN ADDITIONAL SHOT OF MOISTURE CONTINUES AS THE LAST
WAVE RIDES NORTHEAST ALONG THE FRONT AND THIS FEATURE FINALLY
KICKS THE SURFACE LOW OUT TO SEA BY THURSDAY NIGHT. IT IS WORTH
MENTIONING...THAT THIS PATTERN DOES NOT HAPPEN OFTEN...ESPECIALLY
POSTFRONTAL HEAVY SNOWFALL DURING THE LAST HALF OF THE WINTER
SEASON. HOWEVER...THERE DOES SEEM TO BE SOME CONSISTENCY IN THE
MODELS AND NOW THE NAM AND SREF AS THIS EVENT HAS COME INTO THAT
TIME PERIOD. ENSEMBLE MEANS SHOWN FROM WWD PRODUCTS ARE INDICATING
MUCH MORE IN THE WAY OF SNOW AND HAVE AT LEAST COLLABORATED WITH
WWD TO COME UP WITH SOME SLIGHTLY LOWER SNOW VALUES AND SNOWFALL
FORECASTS ARE IN LINE WITH THOSE TRENDS OF COLLABORATION. ANOTHER
HELPFUL INDICATOR OF AT LEAST THE BLOCKING NEEDED FOR THAT
SOUTHWEST TO NORTHEAST ORIENTATION OF THE NEARLY STALLED FRONT IS
THE ENSEMBLE MEAN OF THE NAO. A SHARP DROP IN VALUES FROM THE NAO
PRODUCT ARE OCCURRING DURING THE TIME OF THIS SYSTEMS SET UP.
WHILE NOT NECESSARILY A SHARP DROP INTO NEGATIVE VALUES...THIS
INDICATION WOULD BE ENOUGH FOR SOME BLOCKING OVER THE ATLANTIC AND
IS ENOUGH TO HAVE SOME CONFIDENCE IN THE QPF AND SNOWFALL VALUES
DISPLAYED IN THE FORECAST. IT IS VERY POSSIBLE TO BE GOING
STRAIGHT FROM A FLOOD CONCERN TO A SNOWFALL CONCERN IN A MATTER OF
24 HOURS.

AS FOR SNOW RATIOS INTO WEDNESDAY NIGHT AND THURSDAY...THERE IS
SOME CONCERN AT ONSET OF THIS SYSTEM THAT SOME WARM AIR ALOFT MAY
CREATE SOME FREEZING PRECIP WHICH WOULD LOWER SNOW TOTALS A BIT.
GIVEN ALL THIS...THE GRADIENT MOVING THROUGH WOULD ENSURE COLD
ENOUGH SURFACE TEMPS AND THEREFORE HAVE GONE WITH A STRONG MENTION
IN THE HWO. QPF VALUES WILL GO FROM 2 TO 2.50 INCHES AND SNOWFALL
IN THE 6 TO 8 INCH RANGE.

THE PATTERN GOES QUITE AFTER THURSDAY WITH SURFACE HIGH PRESSURE
MOVING IN AND A NOTICEABLE LACK OF ARCTIC AIR THAT HAS USUALLY
BEEN FOLLOWING THESE SYSTEMS THIS WINTER...THOUGH STILL BELOW
NORMAL HIGHS FOR FRIDAY. SATURDAY HIGHS FINALLY GET BACK TO NEAR
NORMAL. BY SUNDAY...ANOTHER WAVE DROPPING INTO THE SOUTHERN PLAINS
ASSISTS IN SURFACE LOW DEVELOPMENT AND THIS FEATURE TRACK NORTH
BRINGING ADDITIONAL POSSIBLE WINTER WEATHER TO FAR SOUTHEASTERN
KENTUCKY. OBVIOUSLY...THIS SYSTEM IS WAY TOO FAR OUT TO PIN DOWN
WINTER PRECIP IF ANY. BUT IT DOES CONTINUE TO HIGHLIGHT AN ACTIVE
AND WET PATTERN THROUGH THE EXTENDED.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 714 AM EST MON MAR 2 2015

PREVAILING CONDITIONS WILL VARY FROM LIFR TO MVFR AT THE TAT SITES
EARLY THIS MORNING. LOW CIGS WILL LIKELY PERSIST FOR THE NEXT
COUPLE OF HOURS AS A DEPARTING COLD FRONT DRAGS COLD AIR INTO THE
REGION ON NORTHWEST WINDS. PATCHY FREEZING DRIZZLE WILL BE
POSSIBLE AT JKL AND LOZ FOR THE NEXT COUPLE OF HOURS...AND COULD
LEAD TO A LIGHT GLAZE OF ICE FORMING ON ELEVATED SURFACES AND
OTHER OBJECTS. THE PRECIPITATION SHOULD BE OUT OF THE AREA BY 9
AM. THE LOW CIG WE HAVE BEEN SEEING AROUND THE AREA OVERNIGHT AND
EARLY THIS MORNING SHOULD FINALLY BEING TO IMPROVE BY 14 OR
14Z...AT WHICH TIME MVFR CIGS SHOULD PREVAIL AT THE TAF SITES. THE
CLOUDS SHOULD BE WIDELY SCATTERED BY BETWEEN 15 AND 17Z WITH
MOSTLY MID AND HIGH LEVEL CLOUDS DRIFTING ACROSS THE SKY. ANOTHER
ROUND OF RAIN AND WINTRY PRECIP WILL BE POSSIBLE TOWARD THE END OF
THE TAF PERIOD...FROM ROUGHLY 8Z ONWARD.

&&

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

$$

UPDATE...AR
SHORT TERM...AR
LONG TERM...SHALLENBERGER
AVIATION...AR


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