Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 020825
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
325 AM CDT MON MAY 2 2016

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 325 AM CDT MON MAY 2 2016

CHALLENGES TODAY WILL BE CLOUD TRENDS/TEMPERATURES AND THEN
SHOWER/THUNDERSTORM CHANCES LATE TUESDAY. GOOD MODEL AGREEMENT
AMONG THE 02.00Z RUNS AND WILL FOLLOW A BLENDED APPROACH.

FOR TODAY...A SHORT-WAVE ACROSS SOUTHERN MANITOBA WILL DROP SOUTH
ACROSS THE EASTERN DAKOTAS...KEEPING PRECIP WELL WEST OF THE
FORECAST AREA. CLOSER TO HOME...RAP/GFS/NAM BUFKIT SOUNDINGS SHOW
CONVECTIVE TEMPERATURES BEING REACHED THIS AFTERNOON ALLOWING
PARTLY SUNNY SKIES THIS MORNING TO EVENTUALLY FILL-IN WITH BROKEN
THERMAL CUMULUS. COULD SEE SOME SPRINKLES FROM THIS CLOUD DECK
GIVEN HRRR SIMULATED REFLECTIVITY OUTPUT...BUT WITH SURFACE HIGH
PRESSURE AND WINDS 10 KTS OR LESS UP TO AT LEAST 500 HPA...NOT
EXPECTING ANY MEANINGFUL SHOWER ACTIVITY. FOR NOW...WILL KEEP
FORECAST DRY...BUT SPRINKLES MAY NEED TO BE ADDED LATER TODAY.
EXPECT HIGHS TODAY IN THE LOWER 60S.

THERMAL CUMULUS TO DISSIPATE AFTER SUNSET WITH MOSTLY CLEAR SKIES
OVERNIGHT. WITH LIGHT SOUTHWEST WIND...OVERNIGHT LOWS WILL DROP
INTO THE LOWER 40S.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 325 AM CDT MON MAY 2 2016

SUNNY SKIES TUESDAY MORNING WILL GRADUALLY GIVE WAY TO INCREASING
CLOUDS FROM NORTH TO SOUTH AHEAD OF AN APPROACHING COLD FRONT.
AHEAD OF THE FRONT...925 HPA TEMPERATURES RISE TO BETWEEN +13 AND
+15 CELSIUS RESULTING IN AFTERNOON HIGHS FROM THE MID 60S ACROSS
NORTH CENTRAL WI TO AROUND 70 DEGREES ALONG AND SOUTH OF I-90.
BOUNDARY LAYER ALSO DEEPENS TO AROUND 800 HPA WITH ROUGHLY 25 TO
30 KTS TO MIX TO THE SURFACE. SURFACE WINDS WILL BE STRONGEST WEST
OF THE MS RIVER...GUSTING AT TIMES TO 30 MPH OR MORE. ELSEWHERE...
EXPECT WESTERLY WINDS FROM 15 TO 20 MPH WITH OCCASIONAL GUSTS TO
25 MPH.

ATTENTION THEN TURNS TO SHOWER/THUNDERSTORM CHANCES LATE TUESDAY
AFTERNOON/EVENING AS A COLD FRONT MOVES QUICKLY ACROSS THE
FORECAST AREA. CONVERGENCE ALONG THE FRONT...COMBINED WITH UPPER
LEVEL DIFFLUENT SUPPORT FROM THE LEFT EXIT REGION OF 100 KT 300
HPA JET STREAK WILL RESULT IN A BAND OF SHOWERS PROGRESSING FROM
NORTH TO SOUTH. AS A RESULT...INCREASED POPS TO 80 PERCENT LATE
TUESDAY AFTERNOON/EVENING. BUFKIT SOUNDINGS SHOW 100-200 J/KG OF
ELEVATED CAPE WITH FRONTAL PASSAGE...SO A FEW EMBEDDED
THUNDERSTORMS ARE ALSO POSSIBLE. SEVERE WEATHER IS NOT EXPECTED
WITH THE PRIMARY THREATS BEING LIGHTNING AND PERHAPS SOME GUSTY
WINDS TO 40 MPH WITH INVERTED-V SOUNDING IN THE BOUNDARY LAYER.

WEDNESDAY THROUGH FRIDAY WILL BE MOSTLY SUNNY AND DRY AS SURFACE
HIGH PRESSURE DOMINATES THE REGIONAL WEATHER PATTERN. WITH A
COOLER WEDNESDAY (HIGHS UPPER 50S/60S) IN THE WAKE OF TUESDAY
NIGHT/S FRONTAL PASSAGE...TEMPERATURES WILL RISE EACH DAY FOR THE
LATTER HALF OF THE WEEK. HIGHS BY FRIDAY WILL REACH WELL INTO THE
70S AS A HIGHLY AMPLIFIED 500 HPA RIDGE SLIDES EASTWARD ACROSS
THE CONUS.

SHOWER AND THUNDERSTORM CHANCES RETURN FOR THE WEEKEND AS A
PACIFIC TROUGH TOPS THE RIDGE FROM THE NORTH AND A FOUR CORNERS
CLOSED LOW BEGINS TO LIFT NORTHEASTWARD. ENOUGH MODEL DIFFERENCES
AT THIS POINT TO KEEP CHANCE POPS GOING. TEMPERATURES LIKELY TO
RANGE FROM THE MID 60S TO MID 70S.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1120 PM CDT SUN MAY 1 2016

MOSTLY SKC/SCT FROM I-90 NORTH...BUT TO THE SOUTH BKN VFR CIGS HAVE
PERSISTED...AND MAY THROUGH THE NIGHT. SCT-BKN CIGS SHOULD RETURN
FOR THE TAF SITES TOWARD 18Z MONDAY AS CYCLONIC FLOW A LOFT AND
STEEP LOW LEVEL LAPSE RATES FAVOR CU DEVELOPMENT. DON/T THINK -SHRA
ARE A THREAT AT THIS TIME. WINDS LOOK TO STAY LIGHT THANKS TO A
SAGGY PRESSURE GRADIENT...WITH DIRECTION VARIABLE BETWEEN NORTHWEST-
NORTHEAST...THEN MORE VRBL AT NIGHT.

&&

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

$$

SHORT TERM...ROGERS
LONG TERM...ROGERS
AVIATION...RIECK


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