FXUS63 KLMK 241515
AFDLMK
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
1015 AM EST THU DEC 24 2009
...FORECAST UPDATE...
FORECAST MODEL TIME HEIGHT PROFILES CONTINUE TO INDICATE DRY AIR
INTRUDING INTO THE LOWER LEVELS OF THE ATMOSPHERE ON A SOUTHEAST
FLOW THIS AFTERNOON. FOR THIS REASON WE WILL CUT BACK ON POPS AND
EVEN WHERE RAIN DOES OCCUR IT WILL BE LIGHT.
TEMPERATURES HAVE BEEN SLOW TO RISE THIS MORNING AND WE WILL CUT
BACK ON HIGHS ACROSS THE NORTHERN PORTION OF THE FORECAST AREA THIS
AFTERNOON AS A WARM FRONT WILL REMAIN SOUTH OF THAT AREA.
.SHORT TERM (TODAY AND TONIGHT)...
LOW PRESSURE DEVELOPING NEAR DALLAS AT 07Z WILL CONTINUE TO SPIN UP
AS IT MOVES TO LITTLE ROCK TODAY AND PEORIA TONIGHT. AS THIS STORM
SYSTEM INTENSIFIES IT WILL BRING WARM...WINDY...WET WEATHER TO
SOUTHERN INDIANA AND CENTRAL KENTUCKY THIS CHRISTMAS EVE.
RAIN: LIGHT RAIN SHOWERS WILL BE RATHER WIDELY SCATTERED THIS
MORNING AND WILL BE CONCENTRATED WEST OF INTERSTATE 65. AS THE
AFTERNOON PROGRESSES THE SHOWERS WILL BECOME MORE WIDESPREAD IN THE
WEST AND CHANCES OF GETTING WET IN THE EAST WILL INCREASE THOUGH
COVERAGE THERE SHOULD REMAIN SPOTTY. THEN TONIGHT AN AREA OF
WIDESPREAD RAIN WILL SWEEP ACROSS THE ENTIRE REGION BRINGING
EVERYBODY MEASURABLE RAINFALL AS A WARM FRONT PUSHES THROUGH FROM
SOUTHWEST TO NORTHEAST. PRECIPITATION AMOUNTS TODAY WILL RANGE FROM
AROUND A QUARTER INCH IN THE FAR WEST TO A FEW HUNDREDTHS IN THE FAR
EAST. PRECIPITABLE WATER NUMBERS WILL BE NEAR AN
INCH TODAY AND AROUND AN INCH TONIGHT...ABOUT TWO STANDARD
DEVIATIONS FROM NORMAL FOR LATE DECEMBER. TONIGHT GENERAL AMOUNTS OF
1/3 TO 3/4 INCH CAN BE EXPECTED...WITH LOCALLY HEAVIER AMOUNTS.
HOWEVER RAINFALL TOTALS WILL REMAIN WELL BELOW FLASH FLOOD GUIDANCE.
CONVECTION: INSTABILITY WILL REMAIN QUITE WEAK THROUGH THIS EVENT.
HOWEVER VALUES OF CAPE AND TOTAL TOTALS SUGGEST A STRAY RUMBLE OF
THUNDER WILL BE POSSIBLE IN THE WEST BY LATE THIS AFTERNOON AND JUST
ABOUT ANYWHERE TONIGHT.
WINDS: WINDS WILL BE FROM THE EAST/SOUTHEAST TODAY INTO THIS
EVENING...AND THEN TURN TO THE SOUTH WITH THE PASSAGE OF THE WARM
FRONT OVERNIGHT. WINDS WILL APPROACH WIND ADVISORY CRITERIA THIS
AFTERNOON...BUT SHOULD REMAIN JUST BELOW ADVISORY LEVELS (AT LEAST
30 MPH SUSTAINED FOR AN HOUR AND/OR GUSTS TO 40 MPH). HOWEVER IT
WILL BE CLOSE THIS AFTERNOON ESPECIALLY IN THE SOUTHWEST AND IF WE
CAN REALIZE ANY SUNSHINE OR ROBUST CONVECTION THEN SOME STRONGER
WINDS MAY BE ABLE TO MIX DOWN TO THE SURFACE. BETTER CHANCES FOR
ADVISORY LEVEL WINDS WILL COME TONIGHT AS A LOW LEVEL JET CRANKS UP
OVERHEAD WITH NEARLY 60MPH WINDS POSSIBLE JUST A COUPLE THOUSAND
FEET OFF THE SURFACE. CONFIDENCE IN GROUND-LEVEL ADVISORY CRITERIA
WINDS NOT HIGH ENOUGH AT THIS TIME TO ISSUE A SECOND PERIOD ADVISORY
SO WILL LET DAY SHIFT ASSESS THE SITUATION FURTHER.
TEMPERATURES: WITH WARM AIR COMING IN AND TEMPERATURES STARTING THE
DAY QUITE WARM WILL HAVE HIGHS TODAY GENERALLY IN THE 50S DESPITE
RAIN AND CLOUDS. TONIGHT TEMPERATURES WILL STAY NEARLY STEADY OR
POSSIBLY RISE A DEGREE OR TWO BEFORE STARTING TO DROP THROUGH THE
40S TOWARDS MORNING.
THANKS TO PAH AND JKL FOR COORD.
.LONG TERM (FRIDAY - THURSDAY)...
CHRISTMAS DAY - MONDAY...
AT 12Z CHRISTMAS DAY...THE AFOREMENTIONED LOW PRESSURE SYSTEM WILL
BE OVER WESTERN ILLINOIS. THE SYSTEM WILL PUSH IT/S COLD FRONT
THROUGH OUR FORECAST AREA (FA) BETWEEN 10Z TO 14Z CHRISTMAS
MORNING. WE/LL SEE DECLINING RAIN CHANCES THROUGHOUT THE DAY ON
CHRISTMAS AS WE GET DRY SLOTTED. THEN LIGHT LOW LEVEL MOISTURE
SPINNING AROUND THE UPPER LEVEL LOW WILL WORK IT/S WAY BACK INTO THE
AREA CHRISTMAS NIGHT PROVIDING US WITH FLURRIES. TEMPS ON CHRISTMAS
WILL BE TRICKY WITH THE FROPA IN THE MORNING. WE SHOULD SEE QUITE A
GRADIENT IN HIGH TEMPS FROM THE LOW 40S IN WEST CENTRAL KY/SW
INDIANA TO UPPER 40S IN THE CENTRAL KY/BLUEGRASS/SE INDIANA. HIGH
TEMPS WILL OCCUR IN THE MORNING WITH TEMPERATURES FALLING THROUGHOUT
THE REST OF THE DAY INTO THE 30S BY EVENING. IN ADDITION...WE/LL
SEE A WINDY CHRISTMAS DAY WITH GUSTS UP TO AROUND 35-40 MPH IN THE
MORNING AND THEN DECLINING TO AROUND 30 MPH DURING THE AFTERNOON
HOURS.
THE UPPER LEVEL LOW WITH THIS LOW PRESSURE SYSTEM WILL SIT AND SPIN
OVER NORTHERN ILLINOIS/SOUTHERN WISCONSIN ON SATURDAY/FIRST PART OF
SUNDAY AND THEN MOVE EAST SUNDAY NIGHT. THIS LOW WILL PUSH
MULTIPLE VORTICITY WAVES ACROSS THE MIDWEST PROVIDING US FOR
FLURRIES OR LIGHT SNOW SHOWERS SAT-MON. ALTHOUGH THESE WAVES ARE A
BIT DIFFICULT TO TIME...THE BEST CHANCE FOR LIGHT SNOW MAINLY ACROSS
OUR NORTHERN FA WOULD BE SATURDAY NIGHT AND SUNDAY.
HIGH TEMPS FOR SAT-MON LOOK TO BE IN THE 30S WITH LOWS IN THE 20S.
THE REST OF THE FORECAST REMAINS UNCHANGED. THE PREVIOUS DISCUSSION
IS AS FOLLOWS:
TUESDAY - WEDNESDAY...
AN UPPER LEVEL RIDGE WILL MOVE INTO THE REGION TUESDAY AHEAD OF
ANOTHER LOW PRESSURE SYSTEM IN THE SOUTHERN PLAINS AND BRING WARMER
TEMPERATURES TO CENTRAL KY AND SOUTHERN IN. MOISTURE WILL INCREASE
ON SOUTHWEST FLOW AND SKIES WILL ONCE AGAIN BECOME OVERCAST BY
TUESDAY NIGHT BUT EXPECT CONDITIONS TO REMAIN DRY AT THIS TIME.
&&
.AVIATION (12Z TAF ISSUANCE)...
LOW PRESSURE INTENSIFYING NEAR TYLER TEXAS EARLY THIS MORNING WILL
DEEPEN DRAMATICALLY AS IT HEADS TO LITTLE ROCK TODAY...QUINCY
ILLINOIS TONIGHT..AND CEDAR RAPIDS IOWA BY MIDDAY FRIDAY. SCATTERED
SHOWERS WILL BE FOUND AROUND THE AREA THIS MORNING AS BRISK
SOUTH/SOUTHEAST WINDS BRING GULF MOISTURE NORTHWARD. SHOWERS WILL
BECOME MORE WIDESPREAD TONIGHT AS THE LOW NEARS...AND THEN SHOULD
SCATTER BACK OUT CHRISTMAS MORNING AS SOME DRY SLOTTING MOVES IN.
OVERALL...CONDITIONS SHOULD STAY VFR OTHER THAN PERHAPS SOME VERY
BRIEF MVFR CIGS/VSBYS IN QUICKLY PASSING SHOWERS.
WILL HAVE LLWS IN THE TAFS FOR TONIGHT WITH THE MODELS PROGGING VERY
STRONG WINDS JUST OFF THE SURFACE. GFS AND MESONAM HAVE 0.5KM WINDS
THIS EVENING MOSTLY IN THE 50-60KT RANGE. THE STRONG WINDS ALOFT
SHOULD DIMINISH TOWARDS CHRISTMAS MORNING...BUT WINDS WILL CONTINUE
TO BE GUSTY. EAST/SOUTHEAST WINDS TODAY WILL SHIFT TO THE
SOUTH/SOUTHWEST EARLY CHRISTMAS MORNING WITH THE PASSAGE OF A WARM
FRONT
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
UPDATE.........JA
SHORT TERM.....13
LONG TERM......AML
AVIATION.......13
