Area Forecast Discussion
Issued by NWS Jackson, KY

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000
FXUS63 KJKL 280850 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JACKSON KY
350 AM EST WED JAN 28 2015

.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 350 AM EST WED JAN 28 2015

08Z SFC ANALYSIS SHOWS HIGH PRESSURE MOVING THROUGH THE OHIO VALLEY.
THIS HIGH IS PROVIDING A DECENT NIGHT OF RADIATIONAL COOLING FOR THE
VAST MAJORITY OF THE AREA WITH THE ONLY EXCEPTION FOUND IN FAR
EASTERN PARTS OF THE STATE WHERE NORTHEAST LOW LEVEL FLOW IS KEEPING
SOME STRATUS AROUND. IN FACT...A FEW SNOW SHOWERS HAVE BEEN FALLING
OUT OF THESE AS SEEN IN THE KPBX OBS AND THE RADAR IMAGES FROM RLX.
IN THE CLEAR AREAS TEMPERATURES HAVE BEEN FALLING STEADILY WITH THE
RIDGES AND THE VALLEYS LEADING THE PACK...THOUGH AS THE NIGHT HAS
WORN ON THE DEEPER VALLEYS HAVE DROPPED THE FURTHEST...WHILE THE MORE
OPEN LOCATIONS HAVE BEEN LAGGING...THUS FAR. READINGS AT 3 AM VARY
FROM THE MID TEENS ON THE RIDGES AND THOSE SHELTERED VALLEYS WHILE
LOWER 20S ARE FOUND IN MORE OPEN PLACES LIKE SME AND LOZ AS WELL AS
SOUTHERN VALLEYS OF EKQ AND 1A6. DEWPOINTS...MEANWHILE...ARE
GENERALLY IN THE MID TEENS TO NEAR 10 ABOVE AS WINDS REMAIN LIGHT...
GENERALLY FROM THE NORTH TO NORTHEAST.

THE MODELS ARE IN PRETTY GOOD AGREEMENT ALOFT FOR THE SHORT TERM
PORTION OF THE FORECAST AS THEY ALL DEPICT THE RETREAT OF THE DEEP
NORTHEAST TROUGH AND WITH IT THE ENERGY STREAM THAT RAN FROM NNW TO
SSE OVER OUR EASTERN BORDER. BRIEF RIDGING WILL FOLLOW INTO THURSDAY
MORNING FOR KENTUCKY THOUGH ANOTHER DEVELOPING TROUGH WILL BE
TRAILING QUICKLY BEHIND THESE HIGHER HEIGHTS. THIS TROUGH SLIPS INTO
THE SOUTHERN OHIO VALLEY BY MIDDAY THURSDAY WITH A COUPLE OF BATCHES
OF TRAILING ENERGY THAT WILL EVENTUALLY FORM A DEEPER TROUGH FOR THE
NORTHEAST COAST BY WEEK/S END. GIVEN THE MODEL SIMILARITIES IN THE
SHORT TERM...HAVE FAVORED A BLENDED SOLUTION WITH A LEAN TOWARD THE
NAM12 FOR WX DETAILS ON THURSDAY.

SENSIBLE WEATHER WILL FEATURE A CHILLY START TO THE DAY WITH SOME
SINGLE DIGITS POSSIBLE AT DAWN. PLENTY OF SUNSHINE WILL ALLOW
READINGS TO CLIMB SMARTLY INTO THE MID 30S IN THE NORTH AND LOWER 40S
SOUTH EVEN AS HIGH CLOUDS START TO ARRIVE AHEAD OF THE NEXT CLIPPER
SYSTEM. THESE HIGH CLOUDS...AND WINDS STARTING TO REACT TO THE SFC
LOW...WILL LIKELY NOT PREVENT A DECENT DROP OFF IN TEMPERATURES
FOLLOWING SUNSET FOR THE BULK OF THE AREA TONIGHT. EXPECT THE
EASTERN VALLEYS TO FALL OFF THE FURTHEST AND BE THE LAST TO ENGAGE
WITH THE INCREASING SOUTHERN SFC FLOW...WAITING UNTIL CLOSER TOWARDS
DAWN TO BREAK THEIR TEMPERATURE FALL AND START TO RISE. MEANWHILE...
RIDGES AND MORE OPEN LOCATIONS IN THE WEST WILL ONLY SLOWLY DROP OFF
THROUGH THE FIRST PART OF THE NIGHT. EXPECT THE THICKENING CLOUDS AND
INCREASING SOUTHERN WINDS TO ALLOW TEMPS TO CLIMB IN THE HOURS BEFORE
DAWN MOST PLACES ALONG WITH RISING DEWPOINTS. PCPN CHANCES SHOULD
ARRIVE FROM NORTHWEST TO SOUTHEAST DURING THURSDAY MORNING WITH
PLACES LIKELY WARMING QUICK ENOUGH TO PREVENT A MIX AT THE ONSET.
THIS WILL STILL NEED TO BE WATCHED BUT AT THIS POINT IS NOT ENOUGH
OF A CONCERN TO HIGHLIGHT IN THE GRIDS...ZONES...OR HWO. AS THE SFC
LOW PASSES TO THE NORTH LATER THURSDAY...ITS FRONT WILL PUSH THROUGH
A BAND OF RAIN FOR MOST OF THE AREA THAT AFTERNOON. COLDER AIR DOES
FOLLOW ON WEST TO NORTHWEST WINDS FOR LATE IN THE AFTERNOON AND INTO
THE EVENING THURSDAY. AS A RESULT...SOME SNOW MAY MIX IN WITH THE
LINGERING RAIN BY 00Z FRIDAY IN THE NORTHWEST PARTS OF THE AREA.
HAVE ADDED A MIX FOR THIS IN THE WX GRIDS TOWARDS THE END OF THE
SHORT TERM PERIOD.

AGAIN USED THE BCCONSSHORT AS A STARTING POINT FOR TEMPERATURES...
DEWPOINTS...AND WINDS THROUGH THIS EVENING AND THE SUPERBLEND
THEREAFTER. DID MAKE SOME FAIRLY SUBSTANTIVE...TERRAIN BASED...
ADJUSTMENTS TO HOURLY AND MINIMUM TEMPERATURES...AS WELL AS WINDS...
TONIGHT AHEAD OF THE INBOUND FRONTAL SYSTEM. AS FOR POPS...ENDED UP
CLOSE TO A COMBINATION OF THE MAV AND MET NUMBERS THROUGH THE DAY
THURSDAY...THOUGH WITH ADDED TIMING DETAILS IN THE SPATIAL COVERAGE
OF THE POP/WX GRIDS DURING THE AFTERNOON...IN PARTICULAR.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 446 PM EST TUE JAN 27 2015

THERE ARE TWO WEATHER SYSTEMS OF CONCERN TO AFFECT THE REGION DURING
THE PERIOD. ONE FROM THURSDAY INTO FRIDAY...AND ANOTHER FROM LATE
SATURDAY NIGHT INTO MONDAY. THERE IS DECENT MODEL AGREEMENT FOR THE
FIRST SYSTEM. FOR THE SECOND SYSTEM...WHILE THE MODELS AGREE ON IT
COMING INTO BEING...THERE IS A GOOD DEAL OF VARIATION IN ITS TRACK.

THE FIRST SYSTEM IS A COLD FRONT WITH A PARENT LOW PASSING WELL TO
OUR NORTH. PRECIP MAY OCCUR IN THE WARM AIR ADVECTION AHEAD OF THE
FRONT...AS WELL AS ALONG THE FRONT...AND IN THE LINGERING LOW LEVEL
MOISTURE AND STEEP LAPSE RATES WITH UPSLOPE FLOW BEHIND THE FRONT.
PRECIP WILL LIKELY TAKE THE FORM OF RAIN SHOWERS ALONG AND AHEAD OF
THE FRONT. THERE IS A VERY SMALL CHANCE FOR SOME WINTERY PRECIP IN
OUR NW COUNTIES EARLY IN THE DAY THURSDAY...BUT THE PROBABILITY
APPEARS TOO LOW TO WARRANT MENTION AT THIS POINT. ONCE THE LOW LEVELS
CHILL ENOUGH...ANY LINGERING PRECIP SHOULD GO OVER TO SNOW SHOWERS ON
THURSDAY NIGHT.

THE SURFACE LOW WITH THE SECOND SYSTEM IS EXPECTED TO TRACK FURTHER
SOUTH...BUT EXACTLY HOW FAR SOUTH IS THE BIG QUESTION. THE 12Z ECMWF
IS FURTHER SOUTH WITH THE SUPPORTING UPPER LEVEL IMPULSE WHEN
COMPARED TO THE GFS...RESULTING IN ITS SURFACE LOW BEING FURTHER
SOUTH. THE ECMWF SURFACE LOW TRACK IS ENE ACROSS THE JKL FORECAST
AREA...WHILE THE 12Z GFS TAKES IT EAST ACROSS IN AND OH.
INTERESTINGLY...THE 12Z GFS ENSEMBLE MEAN IS MUCH FURTHER SOUTH...
WITH THE LOW TRACKING FROM LOUISIANA TO THE CAROLINA. THE TRACK WILL
HAVE A VERY LARGE IMPACT ON TEMPERATURES AND PRECIP TYPE. THE
NORTHERN TRACK WOULD LEAVE US WITH MAINLY RAIN IN THE MAIN BATCH OF
PRECIP...WHILE THE SOUTHERN TRACK OF THE GFS ENSEMBLE WOULD BRING
SIGNIFICANT SNOW. HAVE USED A MODEL COMPROMISE WHICH IS CLOSE TO THE
ECMWF. THIS GIVES SOME POTENTIAL FOR SNOW AT THE ONSET...WITH A
CHANGE TO RAIN...AND THEN BACK TO SNOW AS THE SYSTEM DEPARTS.
HOWEVER...IT IS A LOW CONFIDENCE FORECAST FOR TEMPS AND PRECIP
TYPE...AND THE SYSTEM BEARS WATCHING.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 115 AM EST WED JAN 28 2015

ASIDE FROM SOME LOW CLOUDS OVER SJS...SKC CONDITIONS WILL PREVAIL
THROUGH THE REST OF THE NIGHT BEFORE HIGH CLOUDS START TO PUSH IN
FROM THE WEST AHEAD OF THE NEXT CLIPPER. WINDS THROUGH THE PERIOD
WILL BE GENERALLY LIGHT FROM THE NORTH TO NORTHEAST INITIALLY THEN
SWITCHING AROUND TO THE SOUTH BY MIDDAY WEDNESDAY.

&&

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

$$

SHORT TERM...GREIF
LONG TERM...HAL
AVIATION...GREIF





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