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 THU OCT 2 2014

.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 325 AM CDT THU OCT 2 2014

IMMEDIATE CONCERNS INCLUDE FOG THIS MORNING AND INCOMING RAIN.

SURFACE MAP EARLY THIS MORNING HAS A WEAK TROUGH EXTENDING N-S
ACROSS MN/IA. WEAKLY CONVERGENT AND VERY DAMP LOWER BOUNDARY LAYER
HAS LED TO SOME AREAS OF DENSE FOG ACROSS PORTIONS OF NORTHEAST
IA/SOUTHEAST MN AND WEST CENTRAL WI. AS A RESULT...A DENSE FOG
ADVISORY IS IN EFFECT UNTIL 10 AM.

OTHERWISE...WATER VAPOR AND RAP 500MB ANALYSIS SHOWING A DEEPENING
LONG WAVE BASICALLY ALONG THE SPINE OF THE ROCKY MOUNTAINS. AT THE
SURFACE...CYCLOGENESIS WAS TAKING PLACE OVER THE TX/OK PANHANDLE.
LIFT AHEAD OF THIS TROUGH AND SURFACE LOW WAS PRODUCING SCATTERED
SHOWERS AN THUNDERSTORMS ACROSS THE PLAINS/MID-MISSISSIPPI RIVER
VALLEY REGION. OVER THE LOCAL AR X FORECAST AREA...BESIDES THE
FOG...SKIES WERE MOSTLY CLOUDY WITH TEMPERATURES IN THE 50S TO THE
LOWER 60S.

FOR TODAY...WILL BE WATCHING THE LOW OVER THE TX/OK PANHANDLE LIFT
NORTHEAST IN MO BY NOON AND NORTHERN IL BY EARLY THIS EVENING. AS
THIS OCCURS...850 MB MOISTURE TRANSPORT/850-500MB FRONTOGENESIS AND
ISENTROPIC LIFT WILL ALL COMBINE FORCES TO SPREAD SHOWERS AND
ISOLATED THUNDERSTORMS INTO THE AREA... BECOMING MORE WIDESPREAD IN
THE AFTERNOON. OTHERWISE...EXPECT HIGHS TO TOP OFF IN THE MIDDLE 60S
TO THE LOWER 70S.

FOR TONIGHT...THE LOW WILL CONTINUE TO LIFT NORTHEAST ACROSS EASTERN
WI. THIS PUTS ARX FORECAST AREA UNDER FAIRLY STRONG 850-500MB
FRONTOGENETIC BAND IN THE 00-06Z TIME FRAME. THIS IS EXPECTED TO
DRIVE WIDESPREAD MODERATE RAINFALL WITH AMOUNTS LIKELY RANGING FROM
1/4 TO 1/2 INCH. THEN AFTER MIDNIGHT...PLAN ON RAIN TAPERING OFF
FROM WEST TO EAST AS THE LOW PULLS INTO EASTERN LAKE SUPERIOR.
STRENGTHENING PRESSURE GRADIENT ACROSS THE AREA IN THE WAKE OF THE
LOW WILL PRODUCE INCREASING NORTHWEST WINDS THROUGH THE OVERNIGHT
HOURS. COLD AIR ADVECTION WILL DROP TEMPERATURES INTO THE MIDDLE 40S
TO AROUND THE 50 DEGREE MARK.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 325 AM CDT THU OCT 2 2014

GUSTY NORTHWEST WINDS WILL OVERSPREAD THE AREA IN THE WAKE OF
DEEPENING SURFACE LOW PULLING INTO EASTERN ONTARIO. PLAN ON
SUSTAINED WIND SPEEDS IN THE 15 TO 25 MPH RANGE WITH GUSTS 25 TO 35
MPH. PV-ADVECTION ASSOCIATED WITH INCOMING MID-LEVEL LOW WILL ALSO
PRODUCE A CHANCE OF SHOWERS MAINLY EAST OF THE MISSISSIPPI RIVER.
COLDER TEMPERATURES/GUSTY NORTHWEST WINDS/RAIN SHOWERS WILL ALL
COMBINE FOR A PRETTY RAW DAY.

AS THE MID-LEVEL LOW ROTATES SOUTHEAST ACROSS THE AREA SATURDAY
NIGHT...LOOKING FOR SCATTERED SHOWERS TO RESULT. AS TEMPERATURES
COOL INTO THE MID/UPPER 30S LATER IN THE NIGHT...THERE IS THE
POSSIBILITY OF A FEW SNOW FLAKES MIXING IN AT TIMES. RAIN SHOWERS
WILL STILL BE POSSIBLE ON SATURDAY MAINLY EAST OF THE MISSISSIPPI
RIVER IN COLD CYCLONIC FLOW. OTHERWISE...ANOTHER RAW AUTUMN DAY ON
TAP AS HIGHS ONLY TOP OFF IN THE MIDDLE/UPPER 40S. CONTINUED COLD
AIR ADVECTION SATURDAY NIGHT WILL DROP TEMPERATURES NEAR THE
FREEZING MARK FOR A GOOD PART OF THE AREA.

LONG WAVE TROUGH/CLOSED LOW WILL LINGER ACROSS THE REGION THROUGH
MONDAY FOR BELOW NORMAL TEMPERATURES. AN EMBEDDED SHORTWAVE TROUGH
LOOKS TO MAKE PASSAGE ACROSS THE AREA ON MONDAY FOR A CHANCE OF
SHOWERS. OTHERWISE...PLAN ON HIGHS SUNDAY AND MONDAY IN THE MIDDLE
40S TO THE MIDDLE 50S WITH OVERNIGHT LOWS IN THE 30S.

FOR TUESDAY AND WEDNESDAY...THE CLOSED LOW FILLS AND LIFTS NORTHEAST
INTO CANADA WITH HEIGHTS BUILDING IN FROM THE WEST. THIS IS EXPECTED
TO PRODUCE A SLOW MODERATION IN TEMPERATURES WITH HIGHS IN THE
50S/FEW LOWER 60S TUESDAY...AND IN THE 60S WEDNESDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1138 PM CDT WED OCT 1 2014

CONFIDENCE INCREASING FOR WIDESPREAD DENSE FOG AT TAF AIRFIELDS
GIVEN SATURATED NEAR SURFACE LAYER...CLEARING SKIES ALOFT AND VERY
LIGHT WIND. EXPECT FOG TO RAPIDLY DEVELOP BETWEEN 02.08Z TO 02.10Z
WITH VISIBILITY DROPPING BELOW 1/4SM AND CEILINGS FROM 100 TO 200
FT AGL. FOG TO GRADUALLY DISSIPATE BETWEEN 02.15Z AND 02.16Z
BEFORE MVFR/IFR CONDITIONS PERSIST THROUGH THE AFTERNOON AND INTO
THE EVENING WITH RAIN SHOWERS INCREASING FROM SOUTHWEST TO
NORTHEAST AS A STRONG LOW PRESSURE SYSTEM MOVES ACROSS THE REGION.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...DENSE FOG ADVISORY UNTIL 10 AM CDT THURSDAY FOR WIZ032.

MN...DENSE FOG ADVISORY UNTIL 10 AM CDT THURSDAY FOR MNZ079-086>088-
     094-095.

IA...DENSE FOG ADVISORY UNTIL 10 AM CDT THURSDAY FOR IAZ008-009-018-
     019.

&&

$$

SHORT TERM...DAS
LONG TERM...DAS
AVIATION...ROGERS


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