Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 110420
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1120 PM CDT THU JUL 10 2014

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 337 PM CDT THU JUL 10 2014

A SHORTWAVE TROUGH WILL MOVE ACROSS SOUTHERN MINNESOTA/NORTHERN
IOWA THIS EVENING AND EDGE INTO WESTERN SECTIONS OF THE FORECAST
AREA AROUND 00Z. THIS WAVE WILL BRING ISOLATED SHOWERS AND MAYBE A
COUPLE OF THUNDERSTORMS TO THESE AREAS AS IT MOVES IN. THIS
ACTIVITY SHOULD APPROACH THE MISSISSIPPI RIVER LATE THIS EVENING
INTO THE OVERNIGHT HOURS AND WILL INCREASE IN COVERAGE AS 850 MB
MOISTURE TRANSPORT EDGES INTO THE FORECAST AREA. INSTABILITY IS
LIMITED SO HAVE HELD THUNDERSTORM COVERAGE TO ISOLATED UNTIL
FRIDAY MORNING. FORECAST MODELS JUST AREN/T DOING THAT GREAT OF A
JOB HANDLING THIS SHORTWAVE. MESOSCALE MODELS SEEM TO HAVE A
BETTER HANDLE ON THIS WAVE SO HAVE LEANED TOWARDS THEM FOR
PRECIPITATION CHANCES LATE TONIGHT INTO FRIDAY. STRONGER 850 MB
MOISTURE TRANSPORT MOVES INTO THE AREA LATE TOMORROW MORNING INTO
THE AFTERNOON HOURS SO THIS IS WHEN WE SHOULD SEE SCATTERED
SHOWERS AND THUNDERSTORMS ACROSS MUCH OF THE FORECAST AREA. A WEAK
FRONTAL BOUNDARY THEN SAGS SOUTH INTO THE REGION LATE FRIDAY
AFTERNOON INTO FRIDAY NIGHT.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 337 PM CDT THU JUL 10 2014

THE BOUNDARY SETTLES IN FRIDAY NIGHT INTO EARLY SATURDAY MORNING
WITH A VERY BAGGY PRESSURE GRADIENT OVER THE FORECAST AREA. THIS
WEAK GRADIENT COMBINED WITH THE EXPECTED RAIN ON FRIDAY ALONG WITH
DEWPOINTS CLIMBING INTO THE MID TO UPPER 60S WILL SET THE STAGE
FOR FOG DEVELOPMENT. THERE IS SIGNALS IN THE SREF/ARW/NMM FOR
DENSE FOG OVER PORTIONS OF THE FORECAST AREA. IF THESE TRENDS
CONTINUE...FOG COVERAGE WILL NEED TO BE INCREASED AND THERE WOULD
BE THE POTENTIAL TO SEE DENSE FOG. WILL HAVE TO KEEP A VERY CLOSE
EYE ON THIS. THE BOUNDARY THEN EDGES SOUTH SATURDAY AFTERNOON INTO
NORTHEAST IOWA/FAR SOUTHWEST WISCONSIN. AFTERNOON 0-3 KM MUCAPE
VALUES CLIMB INTO THE 1500-1700 J/KG RANGE. 0-6 KM BULK SHEAR
ISN/T ALL THAT GREAT SATURDAY AFTERNOON...RANGING FROM 25 TO 35
KTS. HOWEVER...THERE COULD BE SLIGHTLY STRONGER SHEAR SOUTH OF
INTERSTATE 90 WHERE A SHORTWAVE COULD BE A LITTLER STRONGER THAN
WHAT FORECAST MODELS ARE SUGGESTING. THE MAIN WARM FRONT LOOKS TO
BE POSITIONED OVER CENTRAL IOWA INTO NORTHERN ILLINOIS. THIS AREA
COULD SEE BETTER SHEAR FOR SUPERCELLS AND POSSIBLY SOME TORNADOES
NEAR THE FRONT. ACROSS THE LOCAL AREA...PULSE SEVERE STORMS LOOK
TO BE THE MAIN HAZARD WITH LARGE HAIL AND POSSIBLY DAMAGING WINDS.
LOCALLY HEAVY RAINFALL MAY ALSO BE A CONCERN.

AN UNSEASONABLY DEEP TROUGH DIVES INTO THE REGION LATE SUNDAY
INTO MONDAY NIGHT. THERE IS THE POTENTIAL TO SEE SOME STRONGER TO
POSSIBLY SEVERE STORMS SUNDAY AFTERNOON WITH STRONGER SHEAR OVER
THE REGION. HOWEVER...INSTABILITY WILL BE A MAJOR LIMITING FACTOR.
THE COLDEST AIR WILL SETTLE IN FOR TUESDAY WHEN 850 MB
STANDARDIZED ANOMALIES FALL INTO THE -1.5 TO -2.0 RANGE. TUESDAY
WILL LIKELY BE A DAY FOR RECORD COLD HIGH TEMPERATURES. SEE
CLIMATE SECTION BELOW. TEMPERATURES LOOK TO MODERATE A BIT IN THE
WAKE OF THIS TROUGH WEDNESDAY INTO THURSDAY...WITH HIGHS CLIMBING
BACK INTO THE 70S.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1120 PM CDT THU JUL 10 2014

REGIONAL RADARS CONTINUE TO SHOW SOME LIGHT SHOWERS MOVING TOWARD
THE AREA BUT SURFACE OBSERVATIONS SHOW LITTLE IF ANYTHING IS
HITTING THE GROUND AND WHAT IS...IS NOTHING MORE THAN SHOWERS.
THESE SHOWERS ARE IN ASSOCIATION WITH A SHORT WAVE TROUGH MOVING
ACROSS NORTHERN MINNESOTA. THE 11.02Z HRRR SHOWS THE MAIN AREA OF
SHOWERS PASSING NORTH OF THE REGION WITH THE SHORT WAVE TROUGH
WITH JUST THE SPRINKLES COMING THROUGH OVERNIGHT AND WILL CONTINUE
TO SHOW A VCSH FOR THIS ACTIVITY WITH VFR CEILINGS. MORE
CONVECTION HAS FORMED OVER NEBRASKA AHEAD OF THE NEXT SHORT WAVE
TROUGH. THIS WAVE IS SHOWN BY THE 11.00Z NAM TO SLIDE SOUTH OF THE
AREA ACROSS IOWA BUT THE ACTIVITY MAY DISSIPATE AS IT APPROACHES.
BOTH THE HRRR AND NAM SHOW THIS HAPPENING AS THE ACTIVITY MOVES
OUT OF THE CAPE AXIS. WITH THIS ACTIVITY EXPECTED TO MISS THE
AREA...WILL DROP THE VCSH BY MID MORNING WHEN THE GRADIENT BECOMES
TIGHT ENOUGH AND THE MIXING GETS GOING TO PRODUCE SOME GUSTY SOUTH
WINDS. LOOK FOR THESE GUSTS TO DIMINISH EARLY FRIDAY EVENING AS
THE LOW LEVEL INVERSION DEVELOPS AND CUTS OFF THE MIXING.

&&

.CLIMATE...
ISSUED AT 337 PM CDT THU JUL 10 2014

RECORD COOL HIGH TEMPERATURES ARE POSSIBLE ON TUESDAY AS AN
UNSEASONABLY COLD AIRMASS SETTLES OVER THE UPPER MISSISSIPPI
RIVER VALLEY. FORECAST HIGH TEMPERATURES FOR TUESDAY ARE 65 AT
ROCHESTER AND 66 AT LA CROSSE. THESE TEMPERATURES WOULD BREAK THE
RECORD LOWEST HIGH TEMPERATURES FOR JULY 15TH. THE OLD RECORDS ARE
68 AT LA CROSSE SET BACK IN 1962 AND 67 AT ROCHESTER ALSO SET
BACK IN 1962.

&&

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

$$

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


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