Area Forecast Discussion
Issued by NWS La Crosse, WI

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS63 KARX 170846
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
246 AM CST MON NOV 17 2014

.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 246 AM CST MON NOV 17 2014

THE FIRST CONCERN IN THE FORECAST IS WITH THE WINDS TODAY AND THE
POTENTIAL FOR DRIFTING/BLOWING SNOW ALONG WITH SOME FALLING SNOW.
THE UPPER LEVEL LOW OVER SOUTHWEST ONTARIO WILL DRIFT SOUTHEAST
TODAY OVER THE NORTHERN GREAT LAKES. THIS WILL ALLOW A SHORT WAVE
TROUGH ON THE SOUTHWEST SIDE OF THE LOW TO ROTATE ACROSS THE
REGION THIS MORNING. THIS WAVE LOOKS TO BE FAIRLY CHANNELED IN THE
UPPER LEVEL FLOW AND AS A RESULT SHOULD ONLY PRODUCE SOME WEAK PV
ADVECTION IN THE 500-300 MB LAYER. HOWEVER...THE FORCING FROM THIS
WAVE COMBINED WITH THE STRONG CYCLONIC FLOW SHOULD BE ENOUGH TO
HELP GENERATE SOME LIGHT SNOW SHOWERS ACROSS MUCH OF THE AREA BY
MID TO LATE MORNING. THESE SHOULD THEN CONTINUE THROUGH MUCH OF
THE AFTERNOON WITH NEW ACCUMULATIONS OF A HALF INCH OR LESS. AT
THE SURFACE...A TIGHT PRESSURE GRADIENT WILL BE OVER THE REGION ON
THE SOUTHWEST SIDE OF THE SURFACE LOW THAT WILL BE OVER SOUTHERN
ONTARIO. BUFKIT SOUNDINGS FROM BOTH THE 17.00Z NAM AND GFS
SUGGEST LOW LEVEL LAPSE RATES OF 7 TO 7.5 C/KM WILL EXTEND UP
THROUGH ABOUT 800 OR 750 MB BY THE AFTERNOON. HOWEVER...NOT A LOT
OF SUBSIDENCE LOOKS TO RESIDE IN THIS LAYER TO HELP PUSH THE
STRONGER WINDS ALOFT DOWN TO THE SURFACE...SO EXPECTING THE WIND
GUSTS TODAY TO MAINLY BE IN THE MID TO UPPER 20 KNOT RANGE AND
THIS SHOULD BE ENOUGH TO MOVE AROUND THE LIGHT FLUFFY SNOW ACROSS
THE WESTERN SECTIONS OF THE AREA. THIS MOVING SNOW MAY CREATE SOME
ICY SPOTS WHERE IT MOVES ACROSS ROADS AND COMBINED WITH THE
FALLING SNOW...COULD BRIEFLY PRODUCE SOME LOWER VISIBILITIES.
BASED ON THESE EXPECTED CONDITIONS...WILL CONTINUE THE WINTER
WEATHER ADVISORY ACROSS THE WESTERN SECTIONS FOR TODAY.

THE NEXT FORECAST PROBLEM IS WITH THE SNOW CHANCES FOR TUESDAY
NIGHT INTO WEDNESDAY MORNING. THE REGION WILL REMAIN UNDER
NORTHWEST FLOW ALOFT WHICH WILL ALLOW A FAST MOVING AND RELATIVELY
STRONG SHORT WAVE TROUGH TO MOVE OUT OF CENTRAL CANADA AND ACROSS
THE UPPER MIDWEST. THIS WAVE LOOKS LIKE IT SHOULD PRODUCE WEAK TO
MODERATE PV ADVECTION IN THE 500-300 MB LAYER ALONG WITH MODERATE
QG CONVERGENCE IN THE 1000-500 MB LAYER. RIGHT NOW...THE MODELS
ARE IN GOOD AGREEMENT OF DROPPING THE SURFACE LOW ACROSS WESTERN
WISCONSIN LATE TUESDAY NIGHT INTO WEDNESDAY MORNING. WITH THIS
TRACK OF THE SURFACE LOW AND THE FORCING FROM THE SHORT WAVE
TROUGH...WOULD EXPECT TO SEE A BAND OF LIGHT SNOW FALL MAINLY OVER
WISCONSIN AND RAISED THE SNOW CHANCES INTO THE 50 TO 60 PERCENT
RANGE WITH ACCUMULATIONS AROUND AN INCH POSSIBLE.

.LONG TERM...(WEDNESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 246 AM CST MON NOV 17 2014

HIGH PRESSURE LOOKS TO SETTLE IN OVER THE REGION WEDNESDAY NIGHT
AND MAINTAIN ITSELF INTO THE START OF THE WEEKEND. WITH THE HIGH
OVER THE AREA...THE UPPER LEVEL FLOW PATTERN IS EXPECTED TO BECOME
ZONAL AND THEN TURN SOUTHWEST AS A SYSTEM COMES OUT OF THE
SOUTHERN ROCKIES. AS THIS SYSTEM EJECTS OUT OF THE SOUTHWEST...A
SURFACE LOW SHOULD TRACK NORTH/NORTHEAST FROM TEXAS TOWARD THE
GREAT LAKES. CURRENT INDICATIONS ARE THAT THIS SYSTEM WILL BRING
ENOUGH WARM AIR WITH IT TO PUSH TEMPERATURES INTO THE UPPER 30S
FOR SUNDAY ALLOWING MOST OF THE PRECIPITATION TO FALL AS
RAIN...WITH THE POSSIBILITY OF SOME MIXED PRECIPITATION UNTIL THE
WARM AIR ARRIVES. BASED ON THE GFS SOUNDINGS...THERE MAY NOT BE
ANY ICE PRESENT IN THE CLOUDS WHICH COULD ALLOW FROM SOME FREEZING
RAIN...BUT THE 17.00Z ECMWF WOULD INDICATE ICE WOULD BE PRESENT IN
THE CLOUDS...SO FOR NOW...WILL STAY WITH RAIN OR SNOW.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1134 PM CST SUN NOV 16 2014

CONDITIONS FOR THE MOST PART AROUND THE TAF SITES AS WELL AS IN
THE DAKOTAS AND MN ARE IN THE VFR RANGE...IN THE WAKE OF A COLD
FRONT PASSING THROUGH THE TAF SITES. THERE ARE A FEW ISOLATED
POCKETS OF MVFR STRATUS...MAINLY IN NORTHERN MN. ANTICIPATING
CONDITIONS TO STAY VFR EARLY THIS MORNING...THEN AN MVFR DECK
DEVELOP AROUND OR SHORTLY AFTER 12Z AT BOTH TAF SITES AS THE
AIRMASS BEGINS TO DESTABILIZE. BY 14Z...SOME SNOW SHOWERS SHOULD
GET GOING...AND WITH NORTHWEST WINDS INCREASING TO 15-20 KT WITH
GUSTS OF 20-30 KT...BLOWING SNOW APPEARS LIKELY TO OCCUR AT RST.
THAT BLOWING SNOW SHOULD REDUCE VISIBILITIES TO MVFR...AND
POSSIBLY BRIEFLY IFR AT TIMES BUT PINNING WHEN IS UNCERTAIN AT
THIS TIME. CEILINGS AND VISIBILITIES SHOULD BOTH IMPROVE LATE IN
THE DAY DUE TO LOSS OF DAYTIME HEATING. HAVE KEPT MVFR TO VFR
CEILINGS GOING INTO THE EVENING HOURS...THOUGH ITS ENTIRELY
POSSIBLE THE CLOUDS DISSIPATE TOO WITH LOSS OF HEATING. THE
AFOREMENTIONED WINDS DO LOOK TO PERSIST THROUGH THE EVENING...
THOUGH...AS ARCTIC AIR CONTINUES TO FLOW INTO THE TAF SITES WITH A
TIGHT PRESSURE GRADIENT IN PLACE.


&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...WINTER WEATHER ADVISORY FROM 6 AM THIS MORNING TO 6 PM CST THIS
     EVENING FOR MNZ086-087-094-095.

IA...WINTER WEATHER ADVISORY FROM 6 AM THIS MORNING TO 6 PM CST THIS
     EVENING FOR IAZ008-009-018-019.

&&

$$

SHORT TERM...04
LONG TERM...04
AVIATION...AJ



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.