Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 220944
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
344 AM CST MON DEC 22 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 344 AM CST MON DEC 22 2014

THE MAIN FOCUS IN THE SHORT TERM IS ON THE PRECIPITATION CHANCES
AND TYPES.

CURRENTLY...BROAD TROUGHING ALOFT IS ENTERING THE REGION FROM THE
WEST AS SOUTHERLY LOW LEVEL FLOW CONTINUES TO BRING WARMER AIR UP
ACROSS THE EASTERN PLAINS/MISSISSIPPI RIVER REGION. A WEST TO EAST
BAND OF PRECIPITATION IS QUICKLY MOVING INTO NORTHERN WISCONSIN IN
ASSOCIATION WITH A 700MB TROUGH/WARM FRONT. IN THE WAKE OF THIS
700MB TROUGH THERE IS NOT MUCH OF A FOCUS FOR ANY LIFT...SO
PRECIPITATION HAS BEEN RATHER LIMITED TO JUST SOME SCATTERED
LIGHT RAIN SHOWERS/DRIZZLE.

THIS IS EXPECTED TO BE THE TREND THROUGH THE REST OF THIS MORNING
BEFORE A 500MB SHORT WAVE TROUGH CURRENTLY IN ARKANSAS LIFTS NORTH
INTO THE REGION THIS AFTERNOON. THIS TROUGH SHOULD PROVIDE SOME
BETTER FOCUS FOR PRECIPITATION TO BECOME MORE
WIDESPREAD...PARTICULARLY IN NORTHEAST IOWA TO SOUTHERN WISCONSIN.
OVERALL TRENDS IN THE 22.00Z MODELS ARE TO BE SLOWER WITH THE
PRECIPITATION ARRIVING. THIS PRECIPITATION SHOULD DEVELOP ACROSS
THE REGION AS THE DAY PROGRESSES...BUT LIKELY LIGHTER FURTHER TO
THE NORTHWEST. PRECIPITATION TYPE IS ANOTHER ISSUE AS MUCH OF THE
THERMAL PROFILE IS HUGGING THE 0C LINE. SURFACE TEMPERATURES WILL
LIKELY GUIDE THE TRANSITION FROM RAIN TO SNOW...WHICH ADDS SOME
EXTRA UNCERTAINTY TO THIS FORECAST. WHETHER THE CHANGE OVER OCCURS
AT 34F OR 32F WILL MAKE A DIFFERENCE IN SNOW ACCUMULATIONS
TONIGHT. PRECIPITATION AMOUNTS ARE FORECAST TO BE RELATIVELY LIGHT
IN THE AREAS WHERE SNOW IS THE MAIN PRECIPITATION TYPE...SO ONLY
HAVE ABOUT A HALF INCH TO AN INCH OF ACCUMULATION TONIGHT IN A
BAND ARCING FROM NORTH CENTRAL IOWA UP THROUGH SOUTHEAST MINNESOTA
AND THEN OVER TO NORTH CENTRAL WISCONSIN.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 344 AM CST MON DEC 22 2014

THE HEAVIEST PRECIPITATION WITH THIS SYSTEM IS EXPECTED TO COME IN
TUESDAY MORNING AS THE MID LEVEL CLOSED LOW AND SURFACE LOW ENTER
THE REGION FROM THE SOUTH. AGAIN...THE CHANGE OVER FROM RAIN TO
SNOW IS GOING TO BE VERY TRICKY AND WILL AFFECT HOW MUCH SNOW
ACCUMULATES. LIQUID TO SNOW RATIOS WILL BE ON THE LOWER
SIDE...9:1...OF CLIMATOLOGY WITH THIS EVENT DUE TO THE WARM
PROFILE LINGERING NEAR 0C. CURRENTLY HAVE THE HIGHEST SNOW
ACCUMULATIONS OF AROUND 3 TO 5 INCHES IN NORTH CENTRAL WISCONSIN
WHERE COLDER AIR SHOULD KEEP THE MAIN PRECIPITATION TYPE AS SNOW
THROUGH MUCH OF THE EVENT. DUE TO THESE ACCUMULATIONS ON TUESDAY
PLAN TO GO WITH A WINTER WEATHER ADVISORY FOR TAYLOR COUNTY STARTING
THIS EVENING AND RUNNING THROUGH TUESDAY AFTERNOON PENDING
COLLABORATION WITH NEIGHBORING OFFICES.

BEYOND THIS...WEDNESDAY IS NOW LOOKING TO BE MORE ON THE DRY SIDE
WITH THE SYSTEM CLEARING OUT FASTER THAN PREVIOUSLY FORECAST.
850MB TEMPERATURES REALLY ARE NOT THAT MUCH COLDER ON THE BACK
SIDE OF THIS SYSTEM...SO DO NOT EXPECT MUCH OF A DROP OFF GOING
THROUGH THE CHRISTMAS HOLIDAY. THE NEXT FEATURE OF NOTE IS WITH
THE LOW PRESSURE SYSTEM/MID LEVEL TROUGH THAT COMES THROUGH ON
FRIDAY WHICH IS NOW TRENDING MUCH FURTHER NORTH THAN PREVIOUSLY
FORECAST...WHICH MEANS LESS OF AN IMPACT FOR OUR REGION.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1025 PM CST SUN DEC 21 2014

THE SOUTHERLY FLOW OF MOISTURE CONTINUES INTO THE TAF SITES...
RESULTING IN LIFR CEILINGS AT RST AND MVFR CEILINGS AT LSE.
VISIBILITIES HAVE BEEN BETTER THAN THE PAST FEW DAYS...
THOUGH...MVFR TO VFR. CONDITIONS LOOK TO LOWER SOME FOR THE EARLY
MORNING HOURS WITH THE AID OF NIGHTTIME COOLING...BUT THEN SHOULD
SLIGHTLY IMPROVE LATE IN THE MORNING WITH DAYTIME MIXING. AT THIS
TIME CONDITIONS APPEAR TO STAY STATUS QUO THEN THROUGH THE REST OF
THE DAY AS LIGHT RAIN GRADUALLY MOVES INTO THE SITES. SOME
LOWERING OF THE VISIBILITY TO IFR IS POSSIBLE AT RST IN THE
EVENING...DUE TO THE RAIN SWITCHING OVER TO SNOW FROM COOLER AIR
COMING IN.

REGARDING WINDS...EXPECT 10-20 KT WINDS TO PERSIST OVERNIGHT DUE
TO A TIGHT PRESSURE GRADIENT IN PLACE. ONSET OF DAYTIME MIXING
SHOULD CAUSE 20-25 KT GUSTS TO RETURN AT RST...WHICH THEN
DIMINISH LATE. DID NOT INCLUDE GUSTS AT LSE AS GRADIENT IS A
LITTLE WEAKER. WINDS LOOK TO BACK EASTERLY IN THE EVENING AND
DIMINISH AS LOW PRESSURE BEGINS TO MARCH NORTH TOWARDS THE AREA
FROM MISSOURI.


&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&

$$

SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...AJ



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