778
FXUS63 KARX 261201
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
701 AM CDT TUE MAR 26 2019
SHORT TERM
(TODAY AND TONIGHT)
ISSUED AT 305 AM CDT TUE MAR 26 2019
MAIN FORECAST CONCERNS FOR TODAY ARE ON AFTERNOON RELATIVE HUMIDITY
VALUES.
ANOTHER QUIET WEATHER DAY IS EXPECTED ACROSS THE REGION AS HIGH
PRESSURE SLIDES OFF TO THE SOUTHEAST. MOISTURE WILL START TO MAKE A
VERY SLOW RETURN TODAY AS SOUTH/SOUTHWEST WINDS DEVELOP. WILL LIKELY
SEE LOW RELATIVE HUMIDITY VALUES AGAIN TODAY ALONG AND EAST OF THE
MISSISSIPPI RIVER, WHERE READINGS ARE EXPECTED TO DROP INTO THE 15
TO 25 PERCENT RANGE. HAVE LOWERED RH VALUES TODAY, ANTICIPATING THAT
WE SHOULD SEE MIXING TO AROUND 850 MB. OTHERWISE, PLAN ON SOME
PASSING HIGH CLOUDS THROUGH THE DAY. CLOUDS WILL INCREASE TONIGHT AS
SOUTHERLY FLOW ADVECTS STRATUS INTO THE AREA. THE INCREASING WINDS
AND CLOUD COVER SHOULD HELP KEEP LOW TEMPERATURES IN THE 30S.
LONG TERM
(WEDNESDAY THROUGH MONDAY)
ISSUED AT 305 AM CDT TUE MAR 26 2019
AN UPPER SHORTWAVE TROUGH PASSING TO THE NORTH ACROSS CANADA WILL
DRAG A COLD FRONT TOWARDS THE AREA ON WEDNESDAY AND SOUTH OF THE
AREA BY THURSDAY MORNING. AHEAD OF THE FRONT, A THERMAL RIDGE
AXIS WILL NOSE INTO SOUTHERN MN AND WESTERN WI ON WEDNESDAY WITH
925 MB TEMPS PROGGED TO RISE TO 12-15C, WITH HIGHS LIKELY
NEAR OR ABOVE THE 60 DEGREE MARK FOR MUCH OF THE AREA. SOUTHERLY
WINDS WILL BECOME GUSTY WITH A TIGHTENING SURFACE GRADIENT WHILE
MOISTURE TRANSPORT INCREASES WITH STRENGTHENING SOUTHWESTERLY 925-850
MB FLOW.
DESPITE BROAD MODEST MID-LEVEL HEIGHT FALLS/WARM ADVECTION THE
STRONGER SYNOPTIC LIFT WILL REMAIN NORTH OF THE AREA WEDNESDAY INTO
THURSDAY CLOSER TO THE UPPER TROUGH. COULD NOT RULE OUT A SHOWER OR
TWO IN NORTHERN WI ON WEDNESDAY AS A SHORTWAVE SWINGS ACROSS THE
US/CANADIAN BORDER. OTHERWISE, CHANCES ARE LOW FOR MUCH IN THE WAY
OF PRECIP WITH THE FRONTAL PASSAGE, WITH PERHAPS A SHOWER
WEDNESDAY NIGHT OVER NORTHEAST IA/SOUTHWEST WI IF MOISTURE IS DEEP
ENOUGH. AS THE FRONT SINKS SOUTH OF THE REGION THURSDAY, HIGH
PRESSURE WILL APPROACH FROM THE NORTHERN PLAINS WITH LOW-LEVEL
COLD ADVECTION HELPING TO COOL TEMPS DOWN A TOUCH FROM WEDNESDAY.
HOWEVER, WITH LOWS WEDNESDAY NIGHT HOLDING IN THE 30S TO MID 40S,
HIGHS STILL SHOULD REACH THE UPPER 40S TO UPPER 50S.
FRIDAY INTO SATURDAY, AN AMPLIFYING UPPER TROUGH DIGGING SOUTHWARD
INTO THE UPPER MIDWEST WILL INTERACT WITH A SHORTWAVE TROUGH COMING
OUT OF THE PLAINS. OVERALL, THERE'S PRETTY GOOD MODEL AGREEMENT
THAT A SURFACE CYCLONE WILL RIDE NORTHEAST ALONG THE MID-LEVEL
BAROCLINIC ZONE FROM THE SOUTHERN PLAINS INTO THE LOWER GREAT
LAKES. MODEL CONSENSUS WOULD STILL FAVOR AREAS SOUTH OF I-90 FOR
THE HIGHER PRECIP CHANCES FRIDAY INTO EARLY SATURDAY (AND HIGHEST
AMOUNTS SOUTH OF THE AREA). HOWEVER, THERE REMAINS SOME MODEL
SPREAD IN THE PLACEMENT OF THE LOW/NORTHWARD EXTENT OF PRECIP,
LARGELY DUE TO DIFFERENCES IN THE DEGREE OF PHASING BETWEEN THE
NORTHERN/STREAM WAVES. THE 26.00Z ECMWF CONTINUES TO SHOW A BIT
MORE PHASING THAN THE GFS, AND CONSEQUENTLY IS STRONGER/FARTHER
NORTH WITH THE SYSTEM. ON THE NORTHERN PERIPHERY OF THE SYSTEM,
THERE MAY BE ENOUGH COLD AIR IN PLACE FOR SOME SNOW, ESPECIALLY
FRIDAY NIGHT. WITH THE SPLIT FLOW NATURE OF THE SYSTEM, CONFIDENCE
IN DETAILS IS TEMPERED THOUGH AT THIS TIME RANGE.
AFTER THIS SYSTEM EXITS ON SATURDAY HIGH PRESSURE WILL BUILD IN
UNDER NORTHWEST FLOW ALOFT THROUGH THE WEEKEND WITH COOL HIGH TEMPS
IN THE 30S AND 40S.
AVIATION
(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 701 AM CDT TUE MAR 26 2019
VFR CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD. HIGH CLOUDS
WILL MOVE ACROSS THE REGION TODAY THEN WE WILL SEE AN INCREASE IN
LOWER CLOUDS FROM THE SOUTHWEST TONIGHT INTO WEDNESDAY MORNING.
CLOUD BASES LOOK TO REMAIN VFR BUT CANNOT RULE OUT SOME MVFR
CEILINGS AT TIMES AT KRST. LLWS IS EXPECTED LATE TONIGHT INTO
WEDNESDAY MORNING AS WINDS INCREASE INTO THE 35 TO 45 KT RANGE
AT 2 KFT.
FIRE WEATHER
ISSUED AT 305 AM CDT TUE MAR 26 2019
THE DRIER AIRMASS GRADUALLY SHIFTS SOUTHEAST OF THE REGION TODAY,
BUT EXPECT ANOTHER DAY OF LOW RELATIVE HUMIDITY. PLAN ON AFTERNOON
RH VALUES FALLING INTO THE 15 TO 25 PERCENT RANGE ALONG AND EAST OF
THE MISSISSIPPI RIVER. SOUTH/SOUTHWEST WINDS ARE EXPECTED TO INCREASE
TO 10 TO 20 MPH WITH GUSTS TO AROUND 30 MPH ON WEDNESDAY.
HOWEVER, MOISTURE RETURNS TO THE AREA LATE TONIGHT INTO WEDNESDAY
SO MIN RH VALUES ON WEDNESDAY SHOULD BE IN THE 40 TO 50 PERCENT
RANGE. IF THE MOISTURE DOESN'T RETURN TO CENTRAL WISCONSIN, WE
COULD SEE MIN RH VALUES DROP INTO THE 30S OR POSSIBLY THE UPPER
20S.
HYDROLOGY
ISSUED AT 305 AM CDT TUE MAR 26 2019
RIVER LEVELS WILL CONTINUE TO RISE THROUGH LATE WEEK AND THEREAFTER
ALONG THE MISSISSIPPI WITH GENERALLY MINOR TO MODERATE FLOODING
EXPECTED THROUGH THE WEEKEND. WITH CONTINUED SNOWMELT RUNOFF, MINOR
TO MODERATE FLOODING WILL PERSIST ON SEVERAL MS RIVER TRIBUTARIES IN
WISCONSIN, GENERALLY NORTH OF INTERSTATE 90 OVER THE NEXT FEW
DAYS, WITH RIVER LEVELS EXPECTED TO SLOWLY FALL THROUGH LATE WEEK.
MOSTLY DRY WEATHER IS FORECAST THROUGH THURSDAY, WITH THE NEXT
SYSTEM FRIDAY INTO SATURDAY FORECAST TO BRING PRECIP TO AREAS
MAINLY NEAR OR SOUTH OF I-90, WITH THE HEAVIEST PRECIP AMOUNTS
CURRENTLY EXPECTED MAINLY SOUTH OF THE AREA.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
SHORT TERM...WETENKAMP
LONG TERM...JM
AVIATION...WETENKAMP
FIRE WEATHER...WETENKAMP
HYDROLOGY...JM
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