Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 200446
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1146 PM CDT SUN OCT 19 2014

.SHORT TERM...(THIS AFTERNOON THROUGH MONDAY)
ISSUED AT 310 PM CDT SUN OCT 19 2014

SURFACE ANALYSIS SHOWING A WARM FRONT RUNNING NORTH-SOUTH THROUGH
CENTRAL MN INTO A DEEPENING SURFACE LOW NEAR KINL. THE FRONT THEN
EXTENDS NORTHWEST TO LAKE WINNIPEG AS A STATIONARY FRONT WITH COLD
AIR EAST. THE SURFACE CYCLONE IS MOST CLOSELY ASSOCIATED WITH THE
STRONGEST SHORTWAVE TROUGH SOUTH OF LAKE WINNIPEG WHERE
TROPOPAUSE FOLDS DOWN TO NEARLY 750 MB /PER RAP ANALYSIS/...PRETTY
IMPRESSIVE. WATER VAPOR IMAGERY SHOWS WEAKER TROUGH ENERGY MOVING
THROUGH WISCONSIN AT THIS TIME WITH SHORTWAVE TROUGH CURL IN
NORTH-CENTRAL WI 20Z. THE MAIN WATER VAPOR SIGNAL IS VERY DRY AIR
BEHIND THIS FIRST TROUGH...NOT MAKING IT EASY FOR FOR THE STRONGER
LAKE WINNIPEG TROUGH TO CREATE PRECIPITATION ALONE WITHOUT LOW-
LEVEL HELP. MOST OF THE PRECIPITATION WITH THIS SYSTEM IN SRN
CANADA IS EAST OF THE FRONT AND CYCLONE IN VERY LOW CLOUD. THIS
ENTIRE SYSTEM WAS SHIFTING SOUTHEAST TOWARD THE CENTRAL GREAT
LAKES.

WILL BE CLEARING THE SPRINKLES IN THE FORECAST EAST IN THE NEXT
HOURS...AND CLEARING SKIES AS THE WI SHORTWAVE TROUGH PASSES. AIR
MASS IS VERY DRY IN THIS FORCING /PER KMPX AND KGRB 12Z
RAOBS/...BUT SOME STEEPER LAPSE RATES AROUND 7-7.5C/KM IN MID-
LEVELS IS CAUSING 10KFT SHOWERS TO DEVELOP. ONLY HIT AND MISS
SPRINKLES HITTING THE GROUND.

WARM FRONT WILL CONTINUE TO SHIFT IN THIS EVENING AND CYCLONE
WILL PASS THROUGH THRU GREAT LAKES OVERNIGHT. QG FORCING ALOFT
INCREASES OVERNIGHT WITH THE LAKE WINNIPEG SHORTWAVE TROUGH...BUT
THE MORE SUBSTANTIAL DEEPER LIFT REMAINS CLOSER TO THE SURFACE
CYCLONE TRACK - MORE FOR THE NRN GREAT LAKES. AIR MASS IN PLACE
WITH THE FORCING COMING OVER THE FORECAST AREA SUGGESTS NO
WEATHER.

COLD AIR PUSH DIVES INTO WISCONSIN AND GREAT LAKES POST-LOW ON
MONDAY..BRINGING LOWER OVERCAST WITH IT. THE FRONT WILL LIE UP
THROUGH WESTERN WISCONSIN WITH LOWER CLOUDS AND SOME VERY LOW CAPE
EAST OF THE FRONT ACROSS WI. THERE MAY BE SOME SPRINKLES AROUND
NRN-ERN WI MONDAY...HAVE NOT ADD THOSE TO THE FORECAST HOWEVER.

.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)
ISSUED AT 310 PM CDT SUN OCT 19 2014

MONDAY NIGHT-WEDNESDAY...RIDGE BUILDING WILL DOMINATE THIS PERIOD
WITH CLEARING SKIES MONDAY NIGHT. SOME RIVER VALLEY FOG IS
POSSIBLE WEDNESDAY MORNING...BUT SOME SUGGESTION OF WINDS AT THE
TOP OF THE BOUNDARY LAYER COULD BE LIMITING. WILL ADD PATCHY RIVER
VALLEY FOG TO FORECAST FOR NOW.

WEDNESDAY NIGHT THROUGH SATURDAY...
PREDICTABILITY TAKES A NOTICEABLE DROP AFTER WEDNESDAY AS SEEN IN
THE SPREAD OF DETERMINISTIC MODEL GUIDANCE. IN THE LONG WAVE
PATTERN...COMPLEX READJUSTMENT IS OCCURRING IN THIS PERIOD WITH A
A DEEP CLOSED LOW OVER THE EASTERN U.S. AND CENTRAL RIDGING.

WILL CONTINUE TO USE A BLENDED DETERMINISTIC FORECAST FOR RAIN
CHANCES FOR WEDNESDAY NIGHT AND THURSDAY AS IT APPEARS THE
CONSENSUS CONTINUES FOR A SOUTHERLY RETURN FLOW OF MOISTURE AND
SOME WEAK FORCING. SMALL RAIN CHANCES IN THE 30 PERCENT RANGE FOR
NOW ON WED NIGHT AND THURSDAY ARE CONTINUED UNTIL MORE CONFIDENCE
CAN BE BUILT IN THE SIGNAL.
&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1146 PM CDT SUN OCT 19 2014

A COLD FRONT WILL CONTINUE TO PUSH ACROSS THE AREA EARLY IN THE
PERIOD...WITH WINDS BECOMING NORTHWEST TO NORTH FOR LATE TONIGHT...
MONDAY AND MONDAY EVENING. WIND SPEEDS MOSTLY 6-12KTS WITH WITH
DIURNAL WARMING/MIXING ALLOWING FOR SOME 20KT GUSTS AT KRST DURING
THE EARLY/MID AFTERNOON HOURS. QUIET/SKC VFR CONDITIONS THRU 14Z
THIS MORNING. CYCLONIC FLOW WRAPPING ACROSS THE GREAT LAKES WILL
SPREAD SOME LOWER LEVEL MOISTURE/CLOUDS SOUTH ACROSS THE AREA MON...
MAINLY ALONG/EAST OF THE MS RIVER. LEFT KRST WITH SCT STRATO-CU
CLOUDS MON WHILE KLSE LOOKS TO HAVE MORE OF A BKN-SCT VFR CLOUD DECK
MUCH OF MON. SIGNAL FOR THIS MOISTURE TO THIN WITH SOME STRONGER 925-
700MB SUBSIDENCE TO SPREAD ACROSS THE AREA MON EVENING. WILL SCATTER
OUT THE CLOUDS AT KLSE AFTER 23Z FOR NOW...BUT GIVEN WEAK CYCLONIC
925MB FLOW AND PLENTY OF CLOUDS/MOISTURE UPSTREAM ACROSS ONTARIO...
AND A STRONG INVERSION NEAR 850MB...CONFIDENCE IN A QUICK DECREASE
OF CLOUDS MON EVENING IS AVERAGE AT BEST.

&&

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

$$

SHORT TERM...BAUMGARDT
LONG TERM....BAUMGARDT
AVIATION.....RRS


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