Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 021455
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
955 AM CDT THU OCT 2 2014

.UPDATE...DENSE FOG THIS MORNING
ISSUED AT 955 AM CDT THU OCT 2 2014

DENSE FOG ADVISORY HAS BEEN EXTENDED FOR SOUTHEAST MN AND BUFFALO
COUNTY IN WISCONSIN AS CONDITIONS HAVE BEEN SLOW TO IMPROVE THIS
MORNING. SOUNDINGS SHOW STEEP LOW LEVEL INVERSION CONTINUING
THROUGH NOON AND WITH TROUGH AXIS RIGHT THROUGH THE
REGION...LITTLE MIXING EXPECTED TO HELP BREAK THINGS UP.

FOR NORTHEAST IOWA...OBSERVATIONS AND CALLS TO PARTNER GROUPS
INDICATE THAT CONDITIONS HAVE IMPROVED SUCH THAT THE ADVISORY CAN
BE ALLOWED TO EXPIRE.

&&

.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 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 630 AM CDT THU OCT 2 2014

A LOT OF CHALLENGES IN THE FORECAST THROUGH TONIGHT.

FOR VSBYS...SUB 1/2SM FG HAS DEVELOPED ACROSS A PORTION OF
MN/IA...BUT THERE HAS BEEN SOME FLUCTUATION IN THE VSBYS AS
EVIDENCED BY OBSERVATIONS. FEEL IT WILL BE MORE 1/4SM THAN NOT AT
KRST FOR THE EARLY MORNING...SO WILL STICK WITH THAT. GUIDANCE AND
BUFKIT SOUNDINGS SUGGEST SOME IMPROVEMENT BY LATE MORNING...ALTHOUGH
KRST MAY ONLY IMPROVE TO MVFR AT BEST. KLSE HAS AVOIDED THE LOWER
VSBYS...ALTHOUGH OBSERVATIONS SURROUNDING THE SITE HAVE AT LEAST
LOWERED TO MVFR. CONFIDENCE SHAKY WHEN/IF KLSE VSBYS WILL DROP. WILL
LEAN ON THE TRENDS WHICH HAVE KEPT THEM MOSTLY P6SM.

-SHRA WILL MOVE IN LATER TODAY...WITH MOST MESO MODELS SUGGESTING
CLOSER TO 20Z. THEY ALSO WOULD TAKE THE PCPN EAST IN THE 04-06Z
WINDOW. WILL USE THIS TIMING.

A LOT OF CIGS IN THE LIFR/IFR CATEGORIES EARLY THIS MORNING...AND
EXPECT ONLY SMALL DIURNAL IMPROVEMENT THROUGH THE DAY. DON/T SEE VFR
RIGHT NOW...THOUGH COULD OCCUR LATER TONIGHT. AS THE SYSTEM MOVES
OFF TO THE EAST RH FIELDS POINT TO A DECREASE IN THE SATURATION FOR
A SHORT PERIOD OF TIME...WITH MORE MOISTURE ROLLING BACK IN FRIDAY.
SEE SOME POTENTIAL FOR A FEW HOURS OF SCT CLOUDS...BUT WILL HOLD OFF
ON THAT FOR NOW. WILL INSTEAD BUMP CIGS UP...ALTHOUGH KEEP KRST AT
MVFR FOR THE MOMENT.

A LOT OF COMPLEXITY TO THE FORECAST INTO TONIGHT. ANTICIPATE
UPDATES.


&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...DENSE FOG ADVISORY UNTIL NOON CDT TODAY FOR WIZ032.

MN...DENSE FOG ADVISORY UNTIL NOON CDT TODAY FOR MNZ079-086>088-094-
     095.

IA...NONE.
&&

$$

UPDATE...ZT
SHORT TERM...DAS
LONG TERM....DAS
AVIATION.....RIECK


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