Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 010449
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1149 PM CDT MON AUG 31 2015

.SHORT TERM...(TONIGHT AND TUESDAY)
ISSUED AT 224 PM CDT MON AUG 31 2015

BROAD SOUTH TO SOUTHWEST FLOW ACROSS AREA HAS BEEN MOISTENING LOWER
LAYER UP SO BESIDES 70 PLUS SURFACE DEW POINTS MAKING ANOTHER
APPEARANCE...ALSO BATTLING AREAS OF STRATUS FROM OVERNIGHT INVERSION
THAT IS SLOW TO BREAK. EVEN DIURNAL CUMULUS IS OBSCURED BY
ATMOSPHERIC SMOKE MAKING FOR OVERALL POOR DEFINITION TO SKY COVER TO
START THE WEEK.

PASSING SHORT WAVE TROUGH ACROSS MANITOBA IS DRAGGING FRONT OR
TROUGH INTO NORTHERN MINNESOTA...BUT OUR AREA WILL REMAIN IN
SOUTHWEST FLOW INTO TUESDAY. SOME MODEL GUIDANCE TRYING TO GENERATE
SMALL AREAS OF RAIN AHEAD OF THIS BOUNDARY BUT PLAN ON KEEPING DRY
FORECAST GOING.

MAIN ISSUE TONIGHT IS WHETHER ADDITIONAL STRATUS WILL FORM. SEEMS TO
BE CONSISTENT SIGNAL IN SHORT TERM MODEL OF INVERSION STRENGTHENING
AGAIN TONIGHT ALONG WITH ANOTHER SURGE OF LOWER LEVEL MOISTURE.
STRATUS COULD BE TRANSIENT THOUGH...MAINLY IMPACTING NORTHWEST
HALF OF AREA BEFORE EXITING TUESDAY MORNING. CONFIDENCE IS MEDIUM
SO WHILE SKY COVER BUMPED UP...DID NOT COMPLETELY CARRY OVERCAST
ALL NIGHT. GRADIENT TONIGHT SHOULD LIMIT FOG SOMEWHAT SO DO NOT
EXPECT A FULL RECURRENCE OF THIS MORNING.

A FEW DEGREES WARMER ON TUESDAY AS WELL FOR WARM AND MUGGY START OF
SCHOOL FOR MANY.

.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 224 PM CDT MON AUG 31 2015

AMPLIFICATION OF FLOW WILL HIGHLIGHT MEDIUM/LONG RANGE AS MEAN
TROUGH DIGS INTO WESTERN U.S. AND LARGE RIDGE DOMINATES SOUTHERN
PLAINS INTO GREAT LAKES. MAIN PROBLEM IS WHEN TO START RAIN THREAT
AS WEAK IMPULSES CROSS RIDGE INTO NORTHERN MIDWEST.

SOME TIMING DIFFERENCES BUT SEVERAL MODELS HINT AT FIRST SHORT WAVE
EJECTING INTO CORNBELT LATE TUESDAY NIGHT...WITH SUBTLE RAIN RISKS
BY WEDNESDAY ALREADY. THIS IS ON NOSE OF LOW LEVEL MOISTURE
TRANSPORT. EVEN SOME HINTS THAT LEFT OVER BOUNDARIES COULD GENERATE
MORE CONVECTION INTO THURSDAY BUT CONFIDENCE REMAINS RELATIVELY LOW
SO WILL KEEP RAIN CHANCES LOW AT THIS POINT.

THIS ONLY SETS UP FOR SEVERAL MORE WAVES POSSIBLE AS UPPER
TROUGH/LOW BUILDS INTO WESTERN U.S. BY LATE WEEK. COULD SEE RAIN
THREATS ON AND OFF FRIDAY NIGHT INTO THE WEEKEND...ESPECIALLY NORTH
AND WESTERN AREAS AS RIDGE BUILDS STRONG TO THE SOUTHEAST. TOO EARLY
FOR A LOT OF DETAIL YET BUT OVERALL RAIN CHANCES SEEM HIGHER THIS
WEEKEND THAN THIS WEEK LEADING UP TO IT.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1148 PM CDT MON AUG 31 2015

CONFIDENCE IS LOW ON HOW THE NEXT SEVERAL HOURS WILL EVOLVE.
OBSERVATIONS SHOW A FAIRLY WIDESPREAD MVFR FOG HAS SETUP OVER THE
REGION IN SOUTHERLY FLOW...WITH ISOLATED IFR FOG. THERE IS SOME
MOISTURE EXTENDING FROM ABOUT KEAU TO KALO AND WEST THAT IS
FORMING A SCT050 DECK AROUND THE AREA AS WELL.

OVER THE NEXT HOURS THE MODEL GUIDANCE WOULD SUGGEST THAT
CLOUDS/FOG WILL FORM GENERALLY IN THE MOIST AXIS. THUS HAVE
BROUGHT CONDITIONS INTO IFR AT KRST MORE IN THE MOIST PLUME...AND
MVFR AT KLSE.

WITH SOME DRYING WORKING IN FROM THE SOUTHWEST...CONDITIONS SHOULD
IMPROVE RAPIDLY DURING THE EARLY MORNING HOURS.

&&

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

$$

SHORT TERM...SHEA
LONG TERM...SHEA
AVIATION...BAUMGARDT



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