Area Forecast Discussion
Issued by NWS La Crosse, WI

Home | Current Version | Previous Version | Text Only | 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 271135
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
635 AM CDT FRI MAR 27 2015

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 343 AM CDT FRI MAR 27 2015

PRETTY QUIET WEATHER WILL RESIDE OVER THE REGION FOR TODAY AND
SATURDAY. HIGH PRESSURE AT THE SURFACE...CENTERED OVER THE UPPER
MIDWEST THIS MORNING...WILL DRIFT EAST/SOUTHEAST AND BE PARKED
OVER THE GREAT LAKES THROUGH SATURDAY. WITH THE HIGH OVER THE
REGION...THE SHORT WAVE TROUGH THAT COMES ACROSS TODAY WILL HAVE
LITTLE IMPACT AS THE SURFACE LOW WILL BE DEFLECTED WELL TO THE
WEST. THIS WILL SERVE TO KEEP THE PRECIPITATION WITH THIS SYSTEM
OVER WESTERN IOWA AND WELL AWAY FROM THE LOCAL REGION.

THIS AREA OF HIGH PRESSURE WILL GET SHOVED INTO THE OHIO RIVER
VALLEY SATURDAY NIGHT AHEAD OF THE NEXT SYSTEM. A STRONG PACIFIC
SHORT WAVE TROUGH IS EXPECTED TO COME ON SHORE TODAY WITH THE
SOUTHERN PART OF THE WAVE WORKING EAST ACROSS THE NORTHERN ROCKIES
WHILE THE NORTHERN PART OF THE WAVE MOVES INTO CENTRAL CANADA.
THESE TWO WAVES WILL THEN APPROACH THE REGION FROM THE WEST AND
NORTHWEST SATURDAY NIGHT AND MOVE ACROSS SUNDAY BEFORE PHASING
BACK INTO ONE WAVE EAST OF THE AREA. THIS IS EXPECTED TO PRODUCE
STRONG PV ADVECTION IN THE 500-300 MB LAYER AND MODERATE QG
CONVERGENCE IN A DEEP LAYER FROM 1000-300 MB LATE SATURDAY NIGHT
INTO SUNDAY MORNING. THE AREA SHOULD SEE SOME JET DYNAMICS
PROVIDE SOME ADDITIONAL LIFT AS THE LEFT EXIT REGION OF THE JET
MOVES OVER THE REGION. IN THE LOW LEVELS...THE COLD FRONT IS
EXPECTED TO MOVE ACROSS THE AREA SUNDAY MORNING WITH SOME WEAK
FRONTOGENESIS IN THE 850-500 MB LAYER. AHEAD OF THE COLD FRONT
SUNDAY MORNING...UP TO 4 UBAR/S OF UP GLIDE IS SHOWN BY THE 27.00Z
GFS ON THE 290K SURFACE. THERE APPEARS TO BE AMPLE FORCING FOR
PRECIPITATION TO OCCUR ACROSS THE AREA WITH THE BEST CHANCES
SUNDAY MORNING ALONG AND AHEAD OF THE COLD FRONT AND WILL HAVE 60
TO 80 PERCENT CHANCE FROM SOUTH TO NORTH. UNFORTUNATELY...IT LOOKS
LIKE PRECIPITATION TYPES WILL BE A CONCERN WITH THIS SYSTEM. THE
GFS ALONG WITH THE 27.00Z NAM AND ECMWF ALL SHOW AN ELEVATED WARM
LAYER ALOFT AHEAD OF THE COLD FRONT. THE NAM AND GFS BOTH SUGGEST
THE ONLY TIME ICE WILL BE PRESENT IN THE CLOUDS IS NEAR THE COLD
FRONT WHEN THE FORCING IS THE STRONGEST TO CREATE THE DEEPEST
SATURATION. WITH SURFACE TEMPERATURES CURRENTLY EXPECTED TO DIP
BELOW FREEZING SATURDAY NIGHT...THIS MEANS THAT BOTH SOME FREEZING
DRIZZLE AND SLEET WILL BE POSSIBLE UNTIL SURFACE TEMPERATURES WARM
ABOVE FREEZING SUNDAY MORNING AND THE WARM LAYER ALOFT COOLS. THIS
CHANGE OVER TO ALL RAIN SHOULD OCCUR FOR MOST OF THE AREA BY THE
MIDDLE OF SUNDAY MORNING WITH JUST SOME LIGHT RAIN EXPECTED FOR
THE REST OF THE DAY.

.LONG TERM...(SUNDAY NIGHT THROUGH THURSDAY)
ISSUED AT 343 AM CDT FRI MAR 27 2015

THE NORTHWEST FLOW ALOFT WILL CONTINUE INTO NEXT WEEK BUT WITH
DIFFERENCES BETWEEN THE GFS AND ECMWF ON THE TRACK OF THE NEXT
SHORT WAVE TROUGH. THE ECMWF BRINGS THIS ACROSS THE UPPER MIDWEST
MONDAY AND MONDAY NIGHT WHILE THE GFS TAKES IT NORTH OF THE GREAT
LAKES. THESE DIFFERENT TRACKS RESULT IN THE ECMWF PRODUCING SOME
PRECIPITATION ACROSS THE AREA WHILE THE GFS IS DRY AND WILL CARRY
SOME 20 TO 30 PERCENT CHANCES TO COVER THESE DIFFERENCES. THE NEXT
SYSTEM HAS SIMILAR DIFFERENCES IN THE UPPER LEVELS BUT THIS TIME
THE ECMWF HAS THE FARTHER NORTH TRACK. BOTH MODELS DO PRODUCE
PRECIPITATION ACROSS THE AREA WITH A COLD FRONT PASSAGE WEDNESDAY
AND WILL HAVE 30 TO 50 PERCENT CHANCES WITH THIS SYSTEM.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 634 AM CDT FRI MAR 27 2015

VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD. HIGH
PRESSURE BUILDS INTO THE UPPER MISSISSIPPI RIVER VALLEY TODAY AND
WILL REMAIN IN CONTROL THROUGH TONIGHT. A FEW CUMULUS COULD
DEVELOP TODAY WITH CLOUD BASES AROUND 3KFT. WINDS WILL BE
LIGHT...GENERALLY AT 5 KTS OR LESS.

&&

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

$$

SHORT TERM...04
LONG TERM...04
AVIATION...WETENKAMP



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