Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 222333
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
633 PM CDT MON SEP 22 2014

.SHORT TERM...(TONIGHT)
ISSUED AT 240 PM CDT MON SEP 22 2014

WEAK SURFACE TROUGH SPARKED A BAND OF FAIR WEATHER CU ACROSS
CENTRAL. THESE WILL DIE OFF QUICKLY AROUND SUNSET. HIGH PRESSURE TO
THE SOUTH AND A LIGHT WIND FIELD SETS THE STAGE FOR SOME VALLEY FOG
IN THE RIVER VALLEYS.

.LONG TERM...(TUESDAY THROUGH MONDAY)
ISSUED AT 240 PM CDT MON SEP 22 2014

MODELS REMAIN IN VERY GOOD AGREEMENT WITH AMPLIFYING AN UPPER LEVEL
RIDGE ACROSS THE CENTRAL U.S. THIS WEEK. NAEFS 500 MB HEIGHT
ANOMALIES INTO THE WEEKEND AVERAGE +2-3 ACROSS THE NORTHERN PLAINS-
UPPER MISSISSIPPI RIVER VALLEY. MEANWHILE...850 MB TEMP ANOMALIES
HOVER FROM 0-1...NOT RECORD TERRITORY...BUT CERTAINLY SUGGEST ABOVE
NORMAL TEMPERATURES INTO THE WEEKEND. ALL IN ALL...LOOKS LIKE A
FABULOUS EARLY FALL WEEK/WEEKEND WITH WARM TEMPERATURES AND DRY
CONDITIONS.

THAT SAID...IT MAY NOT BE COMPLETELY DRY. YESTERDAY...MODELS WERE
MOVING A SHORTWAVE TROUGH FROM THE WEST COAST...ACROSS THE
NORTHERN/CENTRAL PLAINS TUE/WED. SOLUTIONS THEN SUGGESTED THIS BIT
OF UPPER LEVEL ENERGY WOULD SPLIT...WITH A PIECE MOVING INTO
NORTHERN MN AND SOUTHERN CANADA...AND THE SOUTHERN PIECE
RETROGRADING BACK TO THE WEST. THIS WOULD HAVE LEFT THE LOCAL
FORECAST AREA DRY.

LATEST MODEL RUNS TREND BACK TO A PREVIOUS ECMWF SOLUTION WHICH KEPT
THE SHORTWAVE TOGETHER...AND SPUN IT ACROSS THE REGION. LITTLE IF
ANY FRONTOGENETIC CONVERGENCE WITH THE FEATURE...BUT WEAK WARM AIR
ADVECTION AND MOISTURE TRANSPORT WOULD HELP FUEL SCATTERED RAIN
SHOWERS. MOST OF THIS WOULD HOLD WEST OF THE MISSISSIPPI RIVER. THE
STRONG RIDGE EVENTUALLY KILLS THE FEATURE AS IT TRIES TO WORK
FARTHER EAST...AND KICKS IT BACK WEST AS IT DIES OUT. HAVE HAD A DRY
FORECAST GOING FOR THE WED/WED NIGHT PORTION OF THE FORECAST...WITH
ONLY SMALL CHANCES IN THE FAR WEST TUE NIGHT. GOING TO HOLD THIS FOR
NOW. HOWEVER...SMALL CHANCES MAY HAVE TO BE EXPANDED EAST FOR
WED/WED NIGHT IF TRENDS CONTINUE TO SUGGEST THE SHORTWAVE WILL HOLD
TOGETHER AS IT MOVES IN.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 633 PM CDT MON SEP 22 2014

RIVER VALLEY FOG EXPECTED AT KLSE OVERNIGHT THANKS TO RIDGE OF
HIGH PRESSURE NEARBY AND FORECAST TEMP/DEWPOINT SPREADS WITHIN 5
DEGREES OVERNIGHT. MODEL SOUNDINGS SHOW LAYER OF 10+ KT WINDS
BETWEEN 500 AND 2000 FT...BUT THIS SEEMS OVERDONE. OVERALL THE
FORECAST CONFIDENCE FOR DENSE FOG IS ABOVE AVERAGE AND HAVE
TRENDED FORECAST THAT WAY. SIMILAR TO THIS PAST
MORNING...EXPECTING A LONG PERIOD OF 1/4SM AND VV002 CEILINGS FROM
11-14Z. OTHERWISE...SUNNY SKIES AND LIGHT WINDS FOR TUESDAY FOR
EXCELLENT VFR CONDITIONS AT BOTH KLSE AND KRST.

&&

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

$$

SHORT TERM...RIECK
LONG TERM....RIECK
AVIATION...ZT



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