Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 311718
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1218 PM CDT TUE MAR 31 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 311 AM CDT TUE MAR 31 2015

AFTER DENSE FOG THIS MORNING ACROSS PORTIONS OF SOUTHWEST INTO
CENTRAL WISCONSIN...MAIN FORECAST CONCERN IS ON SHOWER AND
THUNDERSTORM CHANCES LATE WEDNESDAY AFTERNOON THROUGH EARLY THURSDAY
MORNING.

KEEPING A CLOSE EYE ON DENSE FOG DEVELOPING ACROSS PORTIONS OF
SOUTHWEST INTO CENTRAL WISCONSIN...PARTICULARLY FOR THOSE AREAS THAT
RECEIVED RAINFALL YESTERDAY WHICH HELPED BOOST AVAILABLE LOW
LEVEL MOISTURE FOR FOG FORMATION. HAVE ISSUED A DENSE FOG
ADVISORY THROUGH 10 AM FOR THESE AREAS WITH VISIBILITIES EXPECTED
TO FALL TO 1/4 MILE OR LESS AT TIMES. WHERE TEMPERATURES ARE BELOW
FREEZING THE FOG MAY FREEZE TO SOME ROAD SURFACES CREATING
SLIPPERY TRAVEL CONDITIONS.

AFTER THE EARLY MORNING FOG...WILL BE WATCHING LOW PRESSURE DROPPING
SOUTHEAST OUT OF SOUTHWEST ONTARIO...ACROSS LAKE SUPERIOR AND
INTO EASTERN WISCONSIN BY LATE THIS AFTERNOON INTO EARLY  THIS
EVENING. PRECIPITATION WITH THIS FEATURE SHOULD STAY WELL
NORTHEAST OF THE FORECAST AREA. WE SHOULD SEE GOOD MIXING TODAY
WITH A DROP IN DEW POINTS  THIS AFTERNOON AND AN INCREASE IN
WINDS AS WE MIX OUT TO 4000 TO 5000 FT. WE SHOULD SEE AFTERNOON
RELATIVE HUMIDITY VALUES DROP INTO THE MID TO LOWER 30S ACROSS
CENTRAL WISCONSIN AS THIS DEEPER MIXING OCCURS. ALSO...WINDS WILL
INCREASE TO 13 TO 15 MPH WITH GUSTS IN THE 20 TO 25 MPH HOUR
RANGE. WEAK HIGH PRESSURE SLIDES EAST OF THE REGION TONIGHT AS THE
PRESSURE GRADIENT STARTS TO INCREASE WEST OF THE MISSISSIPPI RIVER
AS A TROUGH APPROACHES FROM THE NORTHERN ROCKIES. THE TROUGH WILL
HELP DRIVE A COLD FRONT SOUTHEAST INTO THE REGION ON WEDNESDAY.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 311 AM CDT TUE MAR 31 2015

GULF MOISTURE WILL STREAM NORTHWARD AHEAD OF THE FRONT BRINGING DEW
POINT VALUES INTO THE MID 50S JUST AHEAD OF THE  FRONT ACROSS
PORTIONS OF SOUTHERN MINNESOTA AND NORTHERN IOWA BY LATE
WEDNESDAY AFTERNOON. THESE HIGHER DEW POINTS  WONT MAKE INTO THE
FORECAST AREA UNTIL LATE WEDNESDAY AFTERNOON INTO WEDNESDAY
EVENING SO EXPECTING DEW POINTS TO MIX OUT INTO THE 30S BY EARLY
WEDNESDAY AFTERNOON. ALSO...WITH THE LATER ARRIVAL OF THE FRONT WE
SHOULD SEE TEMPERATURES WARM WELL INTO THE UPPER 60S TO LOWER 70S.
THESE WARM TEMPERATURES...LOWER DEW POINTS...AND BREEZY SOUTH
WINDS OF 15 TO 24 MPH COULD CREATE SOME FIRE WEATHER CONCERNS.
WILL HAVE TO KEEP A VERY CLOSE EYE ON MOISTURE RETURN WEDNESDAY
AFTERNOON. HAVE INCREASES HIGH TEMPERATURES A FEW DEGREE AND
DROPPED DEW POINTS. LOOK FOR MINIMUM RELATIVE HUMIDITY VALUES TO
FALL INTO THE LOWER 30S AND POSSIBLY THE UPPER 20S IF DEEPER
MIXING OCCURS. MOISTURE WILL RAPIDLY INCREASE LATE WEDNESDAY
AFTERNOON INTO WEDNESDAY EVENING AS THE COLD FRONT ADVANCES
EASTWARD. 0-1 KM MUCAPE VALUES CLIMB TO 500 TO 1000 J/KG NEAR AND
JUST WEST OF THE I- 35 CORRIDOR LATE WEDNESDAY AFTERNOON. THESE
CAPE VALUES COMBINED WITH 0-6 KM BULK SHEAR VALUES OF 30 TO 40 KTS
SUGGEST THE POTENTIAL FOR A FEW STRONG TO SEVERE STORMS ALONG THE
FRONT. CAPE REALLY WANES IN THE EVENING AS THE FRONT PUSHES INTO
SOUTHEAST MINNESOTA AND NORTHEAST IOWA SO STORM SHOULD GENERALLY
BE ON A WEAKENING TREND AS THEY MOVE IN. SHOWERS AND STORMS WILL
SPREAD ACROSS THE AREA WEDNESDAY NIGHT AND CONTINUE INTO THE
OVERNIGHT HOURS BEFORE EXITING THURSDAY MORNING. NOT EXPECTING
SEVERE WEATHER AT THIS TIME BUT WILL HAVE TO KEEP A CLOSE EYE ON
THE STORMS THAT FIRE NEAR AND WEST OF THE I-35 CORRIDOR TO SEE IF
THEY CAN HOLD TOGETHER AS THEY PUSH EAST INTO THE FORECAST AREA.
THE ENTIRE FORECAST AREA WILL LIKELY SEE RAIN OUT OF THIS SYSTEM
WIT LOCATIONS ACROSS NORTHEAST IOWA INTO FAR SOUTHWEST WISCONSIN
SEEING THE MOST. RAINFALL AMOUNTS COULD APPROACH AN INCH ACROSS
THESE AREAS. THE FRONT FINALLY EXITS THE REGION BY LATE THURSDAY
MORNING TAKING ANY LINGERING SHOWERS WITH IT. COOLER AIR RETURNS
ON FRIDAY AS 850 MB TEMPS FALL TO -4 TO -7 C. PLAN ON HIGHS ON
FRIDAY RANGING FROM THE LOWER 40S OVER NORTH CENTRAL WISCONSIN TO
THE MID TO UPPER 40S ELSEWHERE. FLOW THEN TRANSITIONS TO ZONAL
FLOW FOR THE WEEKEND INTO EARLY NEXT WEEK AND WE HANG RIGHT IN THE
BAROCLINIC ZONE. A FEW WEAK SHORTWAVES MOVE THROUGH THE REGION
SATURDAY INTO SUNDAY POSSIBLY GENERATING LIGHT RAIN OR
SNOW...DEPENDING ON THE TIMING OF THE WEAK SYSTEMS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1218 PM CDT TUE MAR 31 2015

MAIN CONCERN GOING THROUGH WEDNESDAY MORNING WILL BE GUSTY SOUTH
WINDS AFTER DAYBREAK. THIS WILL BE AHEAD OF A STRONG LOW PRESSURE
SYSTEM MOVING INTO THE NORTHERN PLAINS. PLAN ON SOUTH WINDS
PICKING UP AROUND 25KT GUSTING TO NEAR 35KT AT KRST AND 15KT
GUSTING NEAR 25KT AT KLSE. APPEARS THERE WILL BE SOME MID- LEVEL
CLOUDS WITH BASES AOA 15KFT AFTER 14Z...SO VFR THROUGH THE PERIOD.
LOOKING FURTHER...SHOWERS AND THUNDERSTORMS ARE EXPECTED TO FORM
AHEAD OF A COLD FRONT BY LATE WEDNESDAY AFTERNOON...AFFECTING
KRST/KLSE TAF SITES WEDNESDAY EVENING. MORE DETAIL WILL BE PUT
INTO THIS WITH THE 01.00/01.06Z TAF ISSUANCES.

&&

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

$$

SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION...DAS



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