Area Forecast Discussion
Issued by NWS La Crosse, WI

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KARX 300502
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1105 PM CST THU JAN 29 2015

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 335 PM CST THU JAN 29 2015

AT 3 PM...A 1004 MB SURFACE LOW WAS LOCATED OVER GEORGIAN BAY.
THIS LOW BROUGHT THE DRIZZLE...FREEZING DRIZZLE...AND SNOW GRAINS
LAST NIGHT AND THIS MORNING. IN ADDITION TO THE PRECIPITATION
WINDS GUSTS UP TO 39 MPH AT ROCHESTER INTERNATIONAL AIRPORT AND
40 MPH AT DECORAH MUNICIPAL AIRPORT LATE THIS MORNING.

THE MAIN FORECAST ISSUE FOR TONIGHT INTO FRIDAY MORNING WILL BE
THE CLOUDS. THE LATEST INFRARED SATELLITE IMAGES SHOWS SOME
PARTIAL CLEARING NORTH OF SAINT CLOUD. A FEW BREAKS IN THE
OVERCAST WERE ALSO NOTED IN SOUTHEAST MINNESOTA...NORTHEAST
IOWA...AND WESTERN WISCONSIN. ONE OF THESE BREAKS MOVED THROUGH
THE LA CROSSE AREA BETWEEN 1 PM AND 2 PM. SOUNDINGS ARE PROVIDING
MIXED MESSAGES ON THE AMOUNT OF MOISTURE TRAPPED BELOW 900 MB.
THE NAM KEEPS QUITE A BIT OF MOISTURE IN THIS LAYER THROUGH
30.12Z. MEANWHILE THE GFS SCATTERS OUT THIS MOISTURE EARLY THIS
EVENING. WITH CYCLONIC FLOW ALOFT THIS EVENING...AM CONCERNED
THAT WHATEVER RESIDUAL LOW LEVEL MOISTURE WHICH EXISTS BELOW THE
SUBSIDENCE INVERSION COULD EXPAND AND FILL IN THE HOLES THAT
CURRENTLY EXIST...THUS TRENDED MORE TOWARD THE NAM THIS EVENING
AND THEN WENT MORE TOWARD THE GFS OVERNIGHT. HOWEVER WILL HAVE TO
WATCH HOW THIS DEVELOPS OVERNIGHT. THESE CLOUDS COULD HAVE AN
IMPACT ON THE LOW TEMPERATURES ON FRIDAY MORNING.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 335 PM CST THU JAN 29 2015

ON FRIDAY NIGHT...THE 29.12Z MODELS ARE IN GOOD AGREEMENT THAT A
SHORT WAVE TROUGH WILL MOVE SOUTHEAST ACROSS NORTHERN MINNESOTA
AND NORTHERN WISCONSIN. BOTH THE GEM AND NAM HAVE THEIR MOISTURE A
BIT FURTHER SOUTH THAN EITHER THE GFS OR ECMWF. AS A RESULT...THEY
HAVE SOME LIGHT SNOW AS FAR SOUTH AS INTERSTATE 94. MEANWHILE THE
GFS AND ECMWF CONTINUE TO SHOW THAT THE 925 MB MOISTURE TRANSPORT
AND SYNOPTIC LIFT WILL REMAIN WELL TO THE NORTH OF THE AREA. SINCE
THE GFS AND ECMWF HAVE BEEN THE MOST CONSISTENT...TRENDED THE
FORECAST TOWARD THEM.

ON SATURDAY NIGHT AND SUNDAY...THE MODELS SHOW THAT ARCTIC COLD
FRONT WILL MOVE SOUTHEAST ACROSS THE AREA. WITH THE MUCH OF
FORCING IN THE SOUTHERN STREAM AND DRY AIR BEING ADVECTED INTO
THE AREA FROM THE NORTH...THE SNOW SWATH CONTINUES TO MOVE FURTHER
AND FURTHER SOUTH WITH EACH DETERMINISTIC MODEL RUN. A QUICK LOOK
AT THE 29.12Z GFS ENSEMBLE MEMBERS SHOWS 11 OUT OF 12 MEMBERS HAVE
THE ACCUMULATING SNOW SOUTH OF INTERSTATE 94. THERE WAS EVEN AT
LEAST 1 RUN OF THE 50 ECMWF THAT HAD ITS SNOW NORTH OF INTERSTATE
90. WITH THE CONSENSUS BEING FURTHER SOUTH...LOWERED OR TOOK OUT
THE PRECIPITATION CHANCES NORTH INTERSTATE 90.

FROM MONDAY NIGHT INTO TUESDAY NIGHT...THE DETERMINISTIC GFS/GEM/
ECMWF HAVE 2 QUICK MOVING LOW PRESSURE SYSTEMS MOVING THROUGH THE
REGION. WHILE THERE IS GOOD AGREEMENT AMONGST THESE MODELS...THE
12 29.12Z GFS ENSEMBLE FAMILY HAVE A WIDE VARIETY OF SOLUTIONS.
MUCH OF THIS HAS TO DEAL WITH HOW FAR NORTH THE ARCTIC COLD FRONT
IS ABLE TO ADVANCE NORTHWARD ON THE BACKSIDE OF THE HIGH. AS A
RESULT...STILL DO NOT HAVE A LOT OF HIGH CONFIDENCE ON THE
LOCATION OF THESE SNOW BANDS.

FROM MONDAY THROUGH THURSDAY...THE BOTH THE CFS VERSION 2 AND
ECMWF SHOW QUITE A BIT OF SPREAD IN THEIR TEMPERATURE FORECAST.
FOR MONDAY AND TUESDAY...THE OPERATIONAL ECMWF IS ON THE WARM SIDE
OF THE ENSEMBLE MEAN. MEANWHILE FOR WEDNESDAY AND THURSDAY... THE
OPERATIONAL ECMWF IS ON THE COLDER SIDE ENSEMBLE MEAN. THE
THURSDAY ECMWF LOW TEMPERATURE IS AMONGST THE LOWEST OF ITS 50
MEMBER ENSEMBLE FAMILY. WITH SUCH UNCERTAINTY...JUST STAYED WITH
THE MODEL CONSENSUS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1105 PM CST THU JAN 29 2015

THE MOSTLY MVFR CLOUD DECK HAS CLEARED KRST...AND WILL LIKELY BE IN
AND OUT AT KLSE UNTIL 09Z OR SO. ANTICIPATE VFR CLOUDS/SKC AFTER
THAT...WITH SOME HIGH/MID LEVEL CLOUDS ON FRI AS UPPER LEVEL
SATURATION SPILLS ACROSS THE UPPER LEVEL RIDGE. COULD SEE A RETURN
TO MVFR CIGS OVERNIGHT FRI AS A SHORTWAVE TROUGH TRACKS ACROSS
NORTHERN PARTS OF THE REGION.

AT THE SFC...HIGH PRESSURE BUILDS IN OVERNIGHT...AND WINDS WILL BE
ON THE DECREASE AS A RESULT. LOOK FOR A SWING FROM NORTHWEST TO
SOUTH LATER FRI MORNING AS THE HIGH CENTER MOVES TO THE SOUTHEAST.

&&

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

$$

SHORT TERM...BOYNE
LONG TERM...BOYNE
AVIATION...RIECK


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.