Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 282128
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
328 PM CST WED JAN 28 2015

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 328 PM CST WED JAN 28 2015

AT 3 PM...SURFACE LOWS WERE LOCATED OVER NORTHEAST NEBRASKA AND
WEST OF HUDSON BAY. IN BETWEEN THESE 2 LOW PRESSURE SYSTEMS...
A TROUGH EXTENDED SOUTH ACROSS THE EASTERN DAKOTAS. LIKE THE
28.00Z AND 28.06Z MODELS...THE 28.12Z MODELS SHOW THAT THIS TROUGH
WILL MOVE EAST TONIGHT. AS IT APPROACHES...MODERATE TO STRONG
925 MB MOISTURE TRANSPORT DEVELOPS AHEAD OF IT ACROSS NORTHEAST
IOWA AND SOUTHEAST MINNESOTA THIS EVENING AND WESTERN WISCONSIN
TONIGHT. THIS WILL AID IN MOISTENING THE AIR MASS BELOW 800 MB.
SOUNDINGS GENERALLY SHOW THAT THERE IS NO INTRODUCTION OF ICE FROM
ALOFT...THUS KEEPING THE PRECIPITATION IN FORM OF SUPER COOLED
WATER DROPLETS. THERE WERE A FEW -8C SHOWING AT TIMES...SO TOTALLY
CANNOT RULE OUT MAYBE A BIT OF SNOW...BUT NOT ENOUGH TO
ACCUMULATE. WITH THE PRECIPITATION BEING DRIZZLE...THE MAIN
QUESTION WILL BE HOW COLD WILL BE THE SURFACE TEMPERATURES.
FILTERED SUNSHINE SOUTH OF INTERSTATE 90 HAS ALLOWED SURFACE
TEMPERATURES TO WARM INTO THE LOWER AND MID 30S...AND PAVEMENT
TEMPERATURES TO AROUND 40 DEGREES. WITH THE LOSS OF SUNSHINE...THE
PAVEMENT TEMPERATURES WILL QUICKLY FALL. HOWEVER THE SOUTHERLY
WINDS WILL LIKELY KEEP THE TEMPERATURES AT OR ABOVE FREEZING WEST
AND SOUTH OF INTERSTATE 94. AS A RESULT...THE FREEZING DRIZZLE
THREAT THERE LOOKS TO BE SCATTERED. MEANWHILE NORTH AND EAST OF
INTERSTATE 94 SURFACE TEMPERATURES HAVE BEEN SLOW TO WARM. THIS IS
DUE TO THE SOUTHEAST WINDS BLOWING OVER THE SNOW PACK. WITH
TEMPERATURES ALREADY BELOW FREEZING DECIDED TO ISSUE A FREEZING
RAIN ADVISORY FROM 9 AM TO 6 AM FOR THESE AREAS. ONLY A LIGHT
GLAZE IS EXPECTED TO DEVELOP ON UNTREATED ROADS AND SURFACES.

ON THURSDAY MORNING...THE MODELS SHOW THAT A SECOND SHORT WAVE
WILL MOVE QUICKLY EAST ACROSS THE AREA. WITH SOME MODERATE COLD
AIR ADVECTION IN THE WAKE OF THIS TROUGH...THE TEMPERATURES WILL
COOL ENOUGH FOR THERE TO BE A MIX OF LIGHT SNOW AND FREEZING
DRIZZLE/DRIZZLE. LITTLE...IF ANY...ACCUMULATION IS EXPECTED. ALSO
WITH THE SOUNDINGS SHOWING MOISTURE TRAPPED BELOW THE SUBSIDENCE
INVERSION...THE CLOUDS WILL LINGER THROUGH THE MORNING AND SLOWLY
ERODE DURING THE EVENING AS DRIER AIR ADVECTS INTO THE REGION.

FOR THE ENTIRE DAY THURSDAY...THE MODELS SHOW VERY STEEP LOW LEVEL
LAPSE RATES BETWEEN 950 AND 900 MB. THIS WILL ALLOW THE NORTHWEST
WINDS TO GUST INTO THE 25 TO 30 MPH RANGE ACROSS WESTERN
WISCONSIN...AND INTO THE 30 TO 35 MPH RANGE IN SOUTHEAST MINNESOTA
AND NORTHEAST IOWA.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 328 PM CST WED JAN 28 2015

ON FRIDAY NIGHT...A CANADIAN COLD FRONT WILL MOVE QUICKLY
SOUTHEAST ACROSS THE AREA. THE NAM SHOWS THAT THERE WILL BE ENOUGH
SATURATION FOR SOME LIGHT SNOW. MEANWHILE THE OTHER MODELS SHOW
THAT THE BEST LIFT AND SATURATION WILL REMAIN ACROSS NORTHERN
MINNESOTA...NORTHERN WISCONSIN...AND UPPER MICHIGAN. WITH THE
MODEL CONSENSUS...KEPT THE FORECAST DRY FOR NOW.

FROM SATURDAY AFTERNOON INTO SUNDAY...THE MODELS ARE NOW SHOWING
THAT THE SHORT WAVE FROM FRIDAY NIGHT WILL PUSH THE FRONT FAR
ENOUGH SOUTH THAT MUCH OF THE SNOW ASSOCIATED WITH THIS SYSTEM
WILL REMAIN SOUTH AND WEST OF THE FORECAST AREA. THE ONLY MODEL
STILL SHOWING ADVISORY SNOW IS THE GEM. BOTH THE GFS AND ECMWF
HAVE SIGNIFICANTLY SHIFTED MUCH OF THE SNOW SOUTH INTO THE MID
MISSISSIPPI RIVER VALLEY. SINCE THIS IS A RELATIVELY NEW
DEVELOPMENT...STILL KEPT THE SNOW CHANCES IN THE MODEL CONSENSUS
FOR SATURDAY NIGHT AND SUNDAY...BUT REMOVED THEM FOR SATURDAY
AFTERNOON. IF THIS TREND CONTINUES...FUTURE SHIFTS CAN TAKE THEM
OUT OR LOWER THESE SNOW CHANCES FURTHER.

TEMPERATURES FOR EARLY NEXT WEEK...LOOK TO BE MUCH COLDER WITH
HIGH TEMPERATURES IN THE SINGLE DIGITS AND TEENS...AND LOW
TEMPERATURES ON EITHER SIDE OF ZERO.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1142 AM CST WED JAN 28 2015

MAIN AVIATION CONCERNS IS THE POSSIBILITY OF FREEZING DRIZZLE THIS
EVENING INTO TONIGHT AT BOTH RST AND LSE TAF SITES...AND
LIFR/IFR/MVFR CONDITIONS AT THE TAF SITES THROUGH THE TAF PERIOD.
SURFACE LOW TRACKS INTO SOUTHERN IOWA AND NORTHERN ILLINOIS
TONIGHT. THE LATEST 28.12Z NAM/GFS AND 28.15Z RAP ARE INDICATING
SURFACE TEMPERATURES WILL BE TRICKY THIS EVENING INTO TONIGHT...AS
WARM AIR ADVECTS INTO BOTH TAF SITES THIS AFTERNOON. THE MODELS
SUGGEST TEMPERATURES WILL HOVER AROUND THE FREEZING MARK AND
ABOVE FREEZING THIS EVENING INTO TONIGHT. WITH ENOUGH LIFT AND
THE NEAR SURFACE BOUNDARY LAYER MOIST...PRECIPITATION TYPE WILL BE
ALL LIQUID AND DEPENDING ON TEMPERATURES...THERE IS POTENTIAL FOR
PATCHY FREEZING DRIZZLE TO OCCUR AT BOTH RST AND LSE TAF SITES
FROM 02Z THURSDAY INTO 12Z THURSDAY. AT THIS TIME...WITH THE
FREEZING DRIZZLE EXPECTED TO BE PATCHY...DID NOT INTRODUCE INTO
THE TAFS.

NEXT CONCERN ARE LIFR/IFR/MVFR CONDITIONS AT BOTH TAF SITES THROUGH
THE TAF PERIOD. LOW LEVEL MOISTURE WILL CONTINUE TO LINGER OVER MUCH
OF THE REGION THIS AFTERNOON INTO THURSDAY. CEILINGS WILL HOVER IN
THE LIFR AND IFR CONDITIONS AT RST...AS CEILINGS CURRENTLY BELOW 500
FEET AND RISE INTO THE 500-1000 FEET RANGE LATE THIS AFTERNOON.
THEN...AS SURFACE LOW IN SOUTHERN IOWA AND SUNSET CEILINGS WILL
LOWER BELOW 500 FEET THIS EVENING. AT THE LSE TAF SITE CEILINGS
WILL LOWER INTO THE 500-1000 FEET RANGE AROUND 02Z AND RISE BACK
INTO THE MVFR RANGE AROUND 09Z THURSDAY. WITH SURFACE LOW/FRONT
PASSAGE BETWEEN 09-12Z THURSDAY...PRESSURE GRADIENT TIGHTENS ON
THE BACKSIDE AND NORTHWEST WINDS INCREASE. HAVE INTRODUCE WIND
GUST OF 27 KNOTS AT RST TAF SITE AND 23 KNOTS AT LSE TAF SITE AT
12Z THURSDAY.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...FREEZING RAIN ADVISORY FROM 9 PM THIS EVENING TO 6 AM CST
     THURSDAY FOR WIZ017-029-034-042>044.

MN...NONE.
IA...NONE.
&&

$$

SHORT TERM...BOYNE
LONG TERM...BOYNE
AVIATION...DTJ



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