Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 201729
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1229 PM CDT MON APR 20 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 406 AM CDT MON APR 20 2015

MAIN FORECAST CONCERNS ARE ON STRONG NORTHWEST WINDS TODAY AND RAIN
CHANCES THROUGH THE DAY. FOCUS THEN TURNS TO ANOTHER DAY OF WINDY
CONDITIONS ON TUESDAY WITH ADDITIONAL CHANCES FOR RAIN SHOWERS.

RAIN WAS ONGOING ACROSS THE FORECAST AREA THIS MORNING AS LOW
PRESSURE LIFTED NORTH ACROSS LAKE MICHIGAN. MEANWHILE AN UPPER
TROUGH WAS DIGGING INTO THE UPPER MISSISSIPPI RIVER VALLEY.
900-700 MB FRONTOGENESIS WILL GRADUALLY WEAKEN AND SHIFT EAST
TODAY AS THE SURFACE LOW CONTINUES LIFTING NORTH ACROSS EASTERN
LAKE SUPERIOR TODAY. A TIGHT PRESSURE GRADIENT AND STEEP LAPSE
RATES ACROSS THE FORECAST AREA WILL RESULT IN WINDY CONDITIONS
TODAY WITH NORTHWEST WINDS 20 TO 25 MPH WITH GUSTS APPROACHING 40
MPH AT TIMES. THE OPEN WIND PRONE AREAS OF SOUTHEAST MINNESOTA AND
NORTHEAST COULD JUST TOUCH WIND ADVISORY CRITERIA TODAY. HAVE HELD
OFF ON ISSUING A WIND ADVISORY WITH WINDS FORECAST TO STAY JUST
BELOW CRITERIA. WILL HAVE TO KEEP A VERY CLOSE EYE ON THE WINDS
TODAY. ISOLATED TO SCATTERED SHOWERS LOOK TO DEVELOP THIS
AFTERNOON AS LAPSE RATES STEEPEN. IT WILL BE COOLER TODAY WITH
HIGHS ONLY MAKING IT INTO MID TO UPPER 40S ACROSS MUCH OF THE
FORECAST AREA. THE TROUGH CLOSES INTO AN UPPER LOW ACROSS THE
WESTERN GREAT LAKES TONIGHT AND A LOBE OF VORTICITY ROTATES AROUND
THE LOW AND ACROSS THE FORECAST AREA GENERATING ADDITIONAL RAIN
SHOWERS WITH THE POTENTIAL TO SEE SOME SNOW MIX IN AT TIMES. THE
SNOW WILL BE CONFINED MAINLY ACROSS NORTHERN SECTIONS OF THE
FORECAST AREA...GENERALLY NORTH OF INTERSTATE 90. NOT EXPECTING
ANY SIGNIFICANT ACCUMULATIONS AT THIS TIME.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 406 AM CDT MON APR 20 2015

ANOTHER COOL AND WINDY DAY IS IN STORE FOR THE REGION ON TUESDAY AS
AN ADDITIONAL PIECE OF ENERGY ROTATES AROUND THE LOW. WINDS WILL
ONCE AGAIN INCREASE TO 20 TO 25 MPH WITH GUSTS APPROACHING 40 MPH
AT TIMES. RAIN SHOWERS ARE LIKELY ON TUESDAY...ESPECIALLY ALONG
AND NORTHEAST OF THE INTERSTATE 94 CORRIDOR. CHANCES FOR RAIN AND
SNOW SHOWERS LINGER ACROSS NORTHERN WISCONSIN TUESDAY NIGHT INTO
WEDNESDAY THEN SURFACE HIGH PRESSURE BUILDS IN THURSDAY THROUGH
FRIDAY WITH DRY AND QUIET WEATHER EXPECTED. FORECAST CONFIDENCE
STARTS TO DROP BY SATURDAY NIGHT AS THE ECMWF AND GFS START TO
DIVERGE. THE ECMWF IS SHOWING RIDGING BUILDING INTO THE WESTERN
GREAT LAKES WHILE THE GFS KEEPS NORTHWEST FLOW ACROSS THE REGION.
WILL HAVE TO KEEP A CLOSE EYE ON THIS TIMEFRAME OVER THE NEXT
SEVERAL MODEL RUNS. IF THE ECMWF SOLUTION HOLDS IT COULD BE A
RATHER PLEASANT DAY ON SUNDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1229 PM CDT MON APR 20 2015

MAIN AVIATION CONCERNS ARE MVFR CONDITIONS AND WINDS AT BOTH RST AND
LSE TAF SITES. THE REGION WILL REMAIN UNDER THE INFLUENCE OF LOW
PRESSURE OVER THE GREAT LAKES REGION AND SOUTHERN ONTARIO THROUGH
THE TAF PERIOD. LATEST VISIBLE SATELLITE IMAGERY SHOWS STRATUS DECK
COVERING THE ENTIRE GREAT LAKES REGION WITH THE LATEST METARS
REPORTING CEILING HEIGHTS IN THE MVFR RANGE. THE 20.12Z GFS/NAM
SUGGEST LOW LEVEL MOISTURE/STRATUS DECK TO WRAP AROUND THE LOW
PRESSURE AND INTO THE TAF SITES THROUGH THE PERIOD. WITH FILTERING
OF SUN THROUGH THE STRATUS DECK THIS AFTERNOON...CEILING HEIGHTS
MAY RISE INTO THE VFR RANGE. AS THE SUN SETS THIS EVENING...CEILINGS
MAY LOWER BACK INTO THE MVFR RANGE. PREVIOUS TAFS HAVE GOOD TREND
ON THIS AND WILL FOLLOW WITH MINOR ADJUSTMENTS TO TIMING.

WITH A TIGHT PRESSURE GRADIENT ACROSS THE AREA. NORTHWEST WINDS WILL
CONTINUE TO BE SUSTAINED AT 20 TO 25 KNOTS WITH GUSTS TO NEAR 25 TO
30 KNOTS THIS AFTERNOON INTO TUESDAY AT BOTH RST/LSE TAF
SITES.

&&

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

$$

SHORT TERM...WETENKAMP
LONG TERM....WETENKAMP
AVIATION...DTJ



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