Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 290252
AFDARX

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

.UPDATE...
ISSUED AT 852 PM CST WED JAN 28 2015

HAVE BEEN WATCHING KMPX RADAR THIS EVENING AND THE CLASSIC DZ
ERUPTION. MPING...SURFACE...AND SOCIAL MEDIA REPORTS ALL CONFIRM
THAT FZDZ/DZ IS WIDESPREAD OVER THE MPX FORECAST AREA THIS
EVENING...WITH A THE EXCEPTION YET OF WEST CENTRAL WI. EXPECT THIS
AIR MASS TO CONTINUE SOUTHEAST OVERNIGHT AND DZ/FZDZ TO MOVE IN.
I-94 AND NORTH STILL HAS ALL ROAD AND AIR TEMPERATURES BELOW 32 SO
THE ICING THERE WILL BE MOST WIDESPREAD. BUT IT WILL ONLY BE A
LIGHT GLAZE. WITH ROAD AND AIR TEMPERATURES SO CLOSE TO 32F IN
NWRN FORECAST AREA...AND INCOMING ECHO...THOUGHT IT WAS PRUDENT TO
EXPAND THE FREEZING RAIN ADVISORY. AIR MASS AND LIFT JUST ADVECTS
INTO THAT AREA. DONT THINK THE EXPANDED ADVISORY AREA WILL SEE AS
WIDESPREAD OF A LIGHT ICE GLAZE BECAUSE OF SOME ABOVE FREEZING
READINGS...BUT AREAS WILL GET SO SLICK SO QUICK /I TRADEMARK
THAT/ THAT IT SEEMS PRUDENT.

TAKING A WAIT AND SEE APPROACH WITH AREAS FURTHER SOUTH OF THE
CURRENT ADVISORY. MAINLY WANT TO SEE THE TEMPERATURES...AND
WIDESPREAD NATURE TO THE WEATHER IN THE ADVISORY PRIOR TO
EXPANDING. DEWPOINTS ARE IN UPPER 20S OVER MUCH OF FORECAST AREA
LEADING TO A WET-BULB BELOW FREEZING WITH PRECIPITATION.

TO TV MEDIA...WILL TRY MY BEST TO MAKE THE CALL ON THE ADVISORY
EXPANSION PRIOR TO 10 PM NEWS.
&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 605 PM CST WED JAN 28 2015

SEE AVIATION SECTION BELOW FOR SHORT TERM UPDATE INFO.

.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 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 605 PM CST WED JAN 28 2015

SOME CLEARING HAS MOVED IN FROM THE SOUTHEAST LATE THIS AFTERNOON.
THE AIR MASS MOVING IN FROM THE SOUTHEAST IS DRIER WITH LOWER
DEWPOINTS. THIS WILL CAUSE A DELAY TO LOW CIGS/VSBYS AT THE TAF
SITES OF SEVERAL HOURS AND THUS HAVE MOVED THE TIMING BACK 2 HOURS
WITH THE RECENT 00Z TAF ISSUANCE FOR KLSE AND KRST. VFR
CONDITIONS MAY MOVE INTO KRST FOR A PERIOD OF TIME THIS EVENING
PRIOR TO BOUNDARY LAYER SATURATION OCCURRING AND LOWER
CIGS/VSBYS.

STRONG SURFACE LOW PRESSURE WILL CONTINUE TO MOVE EAST OUT OF IOWA
TOWARD CHICAGO. A TROUGH EXTENDS NORTHWARD INTO MINNESOTA AND THIS
WILL PROVIDE A FOCAL POINT FOR IFR CONDITIONS. THIS WILL MOVE
EAST OVERNIGHT AND SHOULD ADVECT THE AIR MASS CONDITIONS EAST INTO
THE TAF SITES. HOWEVER...CONFIDENCE IS LOW ON HOW FAST THIS WILL
OCCUR WITH DRIER AIR STREAM MOVING IN OVER THE PAST HOURS FROM
EASTERN WI. FURTHER TAF UPDATES MAY BE NEEDED.

WITH TEMPERATURES NOW 33F AND 36F AT KRST AND KLSE
RESPECTIVELY...THE PRECIPITATION TYPE WOULD BE DZ SHOULD IT OCCUR
LATER THIS EVENING. HOWEVER...ONLY A FEW DEGREES OF FALL ARE
NEEDED AT KRST TO GET SOME ICING. DRIER AIR FLOW AND THINNER
CLOUDS COULD PROMOTE A BIT MORE ICING CHANCE SHOULD DZ OCCUR...AS
TEMPERATURES COULD FALL A BIT MORE WITH LESS CLOUD...THEN WITH
ANY DZ ONSET /COOL TO BELOW FREEZING WET-BULB/. EVEN KLSE WILL
HAVE TO BE WATCHED TONIGHT AS 00Z 36F/23F TEMPERATURE/DEWPOINT MEANS
WETBULB TEMPERATURES WILL BE BELOW FREEZING. SO SATURATION WILL
BE A BATTLE IN LOW LEVELS DUE TO DRY AIR...BUT IF IT WINS...COULD


&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...FREEZING RAIN ADVISORY UNTIL 6 AM CST THURSDAY FOR WIZ017-029-
     032>034-042>044.

MN...FREEZING RAIN ADVISORY UNTIL 6 AM CST THURSDAY FOR MNZ079-
     086>088.

IA...NONE.
&&

$$

UPDATE...BAUMGARDT
SHORT TERM...BAUMGARDT
LONG TERM...BOYNE
AVIATION...BAUMGARDT


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