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000
FXUS63 KLMK 101440
AFDLMK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
940 AM EST WED FEB 10 2010

...FORECAST UPDATE...

DYNAMICALLY...LOOKS LIKE AREA SHOULD SEE SNOW COVERAGE
DECREASING...YET STILL HAVE SOME LIGHT SNOW SHOWERS GENERALLY SOUTH
OF A LINE FROM LOUISVILLE TO DANVILLE. STILL HAVE A PLUME OF
MOISTURE COMING SOUTH ACROSS INDIANA THAT LIKELY WILL CLIP THE
BLUEGRASS REGION WITH MORE SNOWS THIS AFTERNOON. WILL CONTINUE THE
SPECIAL WEATHER STATEMENT FOR ALL AREAS SOUTH OF THE CURRENT WINTER
WEATHER ADVISORY. GUSTY WINDS WILL CONTINUE TO BRING BLOWING SNOW
ACROSS THE REGION...BUT SO FAR VISIBILITIES ARE NOT TOO BAD IN OUR
REGION...SEE EASTERN KY FOR THE WORST VSBY`S.

TEMPERATURES HAVE PROBABLY PEAKED WITH READINGS IN THE UPPER 20S AND
EXPECT STEADY OR SLOWLY DROPPING TEMPERATURES FOR THE REST OF THE
DAY. CYCLONIC FLOW TO OUR NORTH AND EAST SHOULD KEEP CLOUDS IN FOR
MOST REGIONS...THOUGH THE SW CWA HAS THE BEST CHANCE TO HAVE SOME
SUN POKE THROUGH THE CLOUDS THIS AFTERNOON.

.SHORT TERM (TODAY AND TONIGHT)...

A RIDGE OF HIGH PRESSURE STRETCHING FROM THE CANADIAN ARCHIPELAGO TO
CENTRAL AMERICA WILL SLOWLY BUILD IN FROM THE WEST DURING THE SHORT
TERM. MEANWHILE LOW PRESSURE WILL BE BOMBING OFF THE EAST COAST. IN
BETWEEN...WE WILL EXPERIENCE BLUSTERY CONDITIONS WITH WNW WINDS OF
15 TO 25 MPH AND GUSTS TO 35 MPH TODAY. WINDS WILL RELAX TONIGHT AS
THE HIGH MOVES IN.

CLOUDS WILL CONTINUE TO PLAGUE THE REGION ALONG WITH SCATTERED SNOW
SHOWERS TODAY NEAR THE BACKSIDE OF A STRONG UPPER LOW. THE MOST
WIDESPREAD SNOW SHOWERS WILL BE OVER THE BLUE GRASS...INCLUDING THE
LEXINGTON AREA. A QUICK INCH OF SNOW WILL BE POSSIBLE WITH THE
HEAVIER SHOWERS.

THE HEAVY WET SNOW THAT FELL YESTERDAY MORNING HAS NOT REALLY BEEN
BLOWING AROUND VERY MUCH DESPITE THE BRISK WINDS. HOWEVER THE LIGHT
SNOW THAT HAS FALLEN OVERNIGHT AND IS PREDICTED FOR TODAY WILL BE
MUCH DRIER AND MORE POWDERY...SO FEEL THAT SOME BLOWING AND DRIFTING
WILL BE POSSIBLE TODAY AND WILL KEEP IN THE FORECAST.

AS FOR TEMPERATURES...AT FIRST BLUSH IT SEEMS THAT THE MERCURY
SHOULDN/T RISE MUCH TODAY GIVEN THE CLOUDS...SNOW BOTH ON THE GROUND
AND IN THE AIR...AND THE CALENDAR READING FEBRUARY. HOWEVER A LOOK
AT REGIONAL TEMPERATURES EARLY THIS MORNING SHOWS THAT ALTHOUGH THE
LMK CWFA IS IN THE LOWER AND MIDDLE TEENS...LOCATIONS IN ILLINOIS
AND MISSOURI ARE IN THE MIDDLE 20S. THIS WARMER AIR WILL SWEEP IN
THIS MORNING AND WILL BRING OUR TEMPERATURES UP SEVERAL DEGREES. THE
TEMPERATURE AT THE WEATHER OFFICE HAD ALREADY RISEN ABOUT A DEGREE
BETWEEN 2AM AND 3AM. THE NAM12 NUMBERS LOOK GOOD FOR HIGHS
TODAY...WHICH ARE STILL ON THE COOL SIDE OF THE GUIDANCE ENVELOPE.
THOSE BLUSTERY WINDS WILL PRODUCE WIND CHILLS IN THE SINGLE DIGITS.

TECHNICALLY MOST LOCATIONS WILL NOT MEET STRICT ACCUMULATION
CRITERIA FOR THE WINTER WEATHER ADVISORY THAT HAS BEEN POSTED.
HOWEVER BETWEEN WHAT SNOW SHOWERS THAT DO DEVELOP PLUS ANY BLOWING
AND DRIFTING SNOW...THE GUSTY WINDS...AND COLD WIND CHILLS...WILL
KEEP THE ADVISORY GOING.

THANKS TO JKL FOR COORD.

.LONG TERM (THURSDAY - TUESDAY)...

THIS EXTENDED FORECAST CONTAINS A HIGH DEGREE OF CONFIDENCE IN
TEMPERATURES FOR THE SOUTHEASTERN STATES AND THE LOWER OHIO VALLEY.
IT WILL STAY COLD! THE ARCTIC OSCILLATION...WHICH IS A GOOD
INDICATOR FOR THE PROPENSITY OF ARCTIC AIR TO INVADE THE EASTERN
CONUS IS STRONGLY NEGATIVE. THESE NEGATIVE VALUES OF -4 TO -5
STANDARD DEVIATIONS BELOW THE MEAN ECHO THE PATTERN EARLIER SEEN
DURING THE FIRST TWO WEEKS IN JANUARY...ALTHOUGH TO A LESSER DEGREE.
STRONG 500MB RIDGING IS FORECAST THIS WEEK ACROSS THE FAR NORTHERN
ATLANTIC AND TROUGHING TO ITS SOUTH ACROSS THE CENTRAL ATLANTIC.
THIS PATTERN WILL KEEP THE SUB-TROPICAL JET DISPLACED WELL SOUTH
ACROSS THE GULF OF MEXICO AND FLORIDA AND WILL ALLOW REPEATED ARCTIC
INTRUSIONS INTO THE UPPER MIDWEST AND THE LOWER OHIO VALLEY.

WINDS WILL DIMINISH BY THURSDAY MORNING AS THE PRESSURE GRADIENT
BETWEEN A DEPARTING STORM OFF THE EAST COAST AND CANADIAN HIGH
PRESSURE OVER THE LOWER MISSOURI VALLEY WEAKENS. WITH STRONG
SUBSIDENCE ALOFT...THE ONLY QUESTION WITH RESPECT TO CLOUDS WILL
CONCERN LOW STRATO-CU...WHICH CAN BE PERSISTENT WITHIN COLD CYCLONIC
FLOW THAT WILL BE CENTERED OVER NEW ENGLAND. TIME HEIGHT RH
CROSS-SECTIONS DO INDICATE AT LEAST PARTIAL CLEARING BY THURSDAY
MORNING AND WILL GO WITH PARTLY CLOUDY SKIES BY THURSDAY AFTERNOON.

BY FRIDAY...HIGH PRESSURE WILL MOVE RIGHT OVER THE COMMONWEALTH AND
SO WINDS WILL BECOME LIGHT AND VARIABLE...AND WILL REMAIN THAT
WAY THROUGH SATURDAY. A STORM SYSTEM ASSOCIATED WITH THE SUBTROPICAL
JET IS FORECAST TO MOVE ACROSS THE GULF FRIDAY. HOWEVER...THE LOWER
OHIO VALLEY WILL REMAIN WELL TO THE NORTH OF THIS SYSTEM.

A COUPLE OF NORTHERN STREAM CLIPPER TYPE SYSTEMS ARE FORECAST TO
DROP SOUTH ACROSS THE MIDWEST AND SCOOT EAST ACROSS THE LOWER OHIO
VALLEY THIS WEEKEND. THE FIRST IS FORECAST TO SPREAD PERHAPS SOME
FLURRIES ACROSS THE AREA EARLY SATURDAY. THE SECOND IS MORE POTENT
AND MAY SPREAD ACCUMULATING SNOWS ACROSS THE AREA SUNDAY. BOTH THE
ECMWF AND THE OPERATIONAL GFS ARE IN GOOD AGREEMENT ON THE BASIC
TRACK OF THE 500MB LOW...MOVING IT SOUTHEAST ACROSS THE KENTUCKIANA
REGION SUNDAY AFTERNOON. BOTH OPERATIONAL MODELS GENERATE A THIN
STRIP OF SNOW EXTENDING FROM CENTRAL ILLINOIS THROUGH EASTERN
KENTUCKY SUNDAY. LOOKING AT THE PRECIP PLUMES FROM THE ENSEMBLE
GFS...ALMOST ALL SHOW AT LEAST LIGHT SNOW ACCUMULATIONS SUNDAY.

ONCE THIS SECOND CLIPPER SYSTEM EXITS LATE SUNDAY...REINFORCING
ARCTIC AIR WILL BRING COLD TEMPERATURES FOR MONDAY AND TUESDAY OF
NEXT WEEK.

&&

.AVIATION (12Z TAF ISSUANCE)...

WINDS WILL BE THE MAIN CONCERN FOR AVIATION DURING THIS CHILLY TAF
PERIOD. TODAY WINDS WILL COME FROM THE WNW AROUND 13 TO 18 KNOTS
WITH GUSTS TO AROUND 25 KNOTS. WINDS WILL FINALLY SETTLE DOWN TO
AROUND 10 KNOTS TONIGHT...STILL OUT OF THE WNW...AND BECOME SLOWER
STILL THURSDAY MORNING AT SDF.

THOUGH THERE IS CLEARING OVER NORTHERN ILLINOIS...PREFERRED TO GO
ALONG WITH THE PESSIMISTIC MODEL PROGS SHOWING MVFR STATOCU HANGING
TOUGH THROUGH THE DAY AND INTO TONIGHT GIVEN THE COLD FLOW OFF THE
LAKES AND THE UPPER LOW NOT THAT FAR OFF TO OUR EAST.

OCCASIONAL SNOW SHOWERS MAY BRIEFLY TAKE VSBYS DOWN BELOW VFR...BUT
THEY SHOULD BE THE EXCEPTION TO THE RULE ESPECIALLY AT THE WESTERN
TAF SITES.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...WINTER WEATHER ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR
     KYZ029>043-045>049-055>057-067.

IN...WINTER WEATHER ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR
     INZ076>079-084-090>092.

&&

$$

UPDATE.........RJS
SHORT TERM.....13
LONG TERM......JSD
AVIATION.......13