Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 260850
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
350 AM CDT SUN JUL 26 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 350 AM CDT SUN JUL 26 2015

EARLY THIS MORNING...A CONVECTIVE COMPLEX ACROSS SOUTH-CENTRAL MN
INTO NORTHWEST IA WILL TRACK EAST-SOUTHEAST IMPACTING AREAS
PRIMARILY WEST OF THE MS RIVER. THE STRONGEST STORMS WITHIN THIS
COMPLEX ARE ACROSS WEST-CENTRAL IA NEAR THE HIGHEST MID-LEVEL
MOISTURE TRANSPORT AND SURFACE WARM FRONT. FARTHER NORTH...SEVERE
THUNDERSTORMS ARE NOT EXPECTED ACROSS THE FORECAST AREA WITH THE
PRIMARY THREATS BEING BRIEF HEAVY RAIN AND LIGHTNING. THESE
THUNDERSTORMS SHOULD BE OUT OF THE AREA NO LATER THAN NOON...BUT
SOME CONVECTIVE RE-DEVELOPMENT IS POSSIBLE MAINLY WEST OF THE
RIVER THIS AFTERNOON. WILL KEEP 20 TO 30 POPS FOR THIS AREA...BUT
SEVERE WEATHER IS NOT EXPECTED.

925 HPA TEMPERATURES TODAY RISE 1 TO 2 CELSIUS COMPARED TO
YESTERDAY...SO EXPECT AFTERNOON HIGHS IN THE MID TO UPPER 80S WITH
SOME 90 DEGREE READINGS ACROSS WESTERN WI. BOUNDARY LAYER MIXES TO
NEAR 700 HPA BY MID-AFTERNOON EAST OF THE MS RIVER AND THIS SHOULD
PROMOTE DRYING AT THE SURFACE WITH RELATIVE HUMIDITY BRIEFLY
DIPPING BELOW 40 PERCENT. LIGHT SOUTH-SOUTHEAST WINDS WILL
CONTINUE THROUGH THE DAY. TONIGHT WILL BE WARM BUT DRY WITH LOW
TEMPERATURES FROM THE MID 60S TO NEAR 70 DEGREES.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 350 AM CDT SUN JUL 26 2015

THERMAL PROFILE CHANGES LITTLE ON MONDAY...BUT NEAR SURFACE MOISTURE
CONTINUES TO INCREASE WITH DEWPOINTS RISING INTO THE LOWER 70S. WITH
AFTERNOON HIGHS AGAIN IN THE UPPER 80S TO NEAR 90 DEGREES...MUCAPE
EASILY RISES INTO THE 2000 TO 4000 J/KG RANGE. HOWEVER...PRIMARY
MID-LEVEL MOISTURE TRANSPORT IS WELL WEST OF THE FORECAST AREA AND
A WEAK SURFACE BOUNDARY REMAINS ACROSS IA. AS A RESULT...WILL KEEP
DRY FORECAST FOR MONDAY...ALTHOUGH IT WILL BE MUGGY WITH HEAT
INDICES RISING INTO THE MID 90S.

SURFACE WARM FRONT FINALLY BEGINS TO LIFT NORTHWARD MONDAY NIGHT
INTO TUESDAY MORNING IN RESPONSE TO APPROACHING EASTERN PACIFIC
TROUGH. MODELS SHOW A 40 TO 50 KT 850 HPA NOCTURNAL JET MONDAY
NIGHT IN THE VICINITY OF THE FRONT ACROSS CENTRAL MN. WITH THIS
SET-UP WITHIN A MOIST/UNSTABLE AIR MASS...SOME KIND OF CONVECTIVE
COMPLEX IS LIKELY BUT ITS TIMING AND LOCATION ARE UNCERTAIN. AT
THIS TIME...WILL KEEP HIGHEST CHANCE POPS MONDAY NIGHT INTO
TUESDAY ACROSS THE NORTHWEST HALF OF THE FORECAST AREA.

CONVECTIVE EVOLUTION TUESDAY MORNING MAY HAVE AN IMPACT ON
TEMPERATURES/HEAT INDICES...AS WELL AS ADDITIONAL THUNDERSTORM
CHANCES LATER IN THE DAY. FOR NOW...GENERAL IDEA THAT
STRENGTHENING CAP WITH 700 HPA TEMPERATURES RISING INTO THE 11 TO
13 CELSIUS RANGE WILL SQUASH ADDITIONAL CONVECTION UNTIL COLD
FRONTAL PASSAGE TUESDAY NIGHT STILL HOLDS. IN THIS SCENARIO...
SURFACE TEMPERATURES RISE INTO THE LOWER 90S TUESDAY AFTERNOON
WITH DEWPOINTS INTO THE MID 70S...RESULTING IN HEAT INDICES ABOVE
100 DEGREES. THUNDERSTORMS SHOULD IGNITE NEAR THE COLD FRONT
TUESDAY NIGHT. SOME OF THESE STORMS COULD BECOME STRONG TO SEVERE
AS DEEP LAYER SHEAR/FORCING FOR ASCENT INCREASES OVERNIGHT.

MUCH COOLER/DRIER AIR MASS MOVES INTO THE REGION WEDNESDAY THROUGH
FRIDAY IN THE WAKE OF TUESDAY NIGHT/S FRONTAL PASSAGE. DAILY HIGHS
WILL RANGE FROM THE UPPER 70S TO LOWER 80S WITH DEWPOINTS
GENERALLY IN THE 50S TO LOWER 60S. DRY CONDITIONS WILL BE THE RULE
THE LATTER HALF OF THE WEEK WITH BROAD SURFACE HIGH PRESSURE
FIRMLY IN CONTROL ACROSS THE NATION/S MID-SECTION.

THE NEXT BEST CHANCE FOR THUNDERSTORMS WILL BE FRIDAY NIGHT INTO
SATURDAY AS WEAK WAVES MOVE THROUGH NORTHWEST FLOW ALOFT. HOWEVER...
MODEL CONSENSUS IS POOR THIS FAR OUT LENDING TO LOW OVERALL
CONFIDENCE FOR PRECIPITATION.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 945 PM CDT SAT JUL 25 2015

CONVECTIVE COMPLEX OVER SD EXPECTED TO CONTINUE/TAKE TURN
SOUTHEAST...PER CORFIDI VECTORS...OVERNIGHT. THIS TRAJECTORY WOULD
KEEP IT WELL WEST OF KLSE...AND MOST MESO MODELS KEEP IT WEST OF
KRST TOO. WILL FOLLOW SUIT AND KEEP FORECAST RAIN FREE FOR NOW.
EXPECT MOSTLY MID/HIGH LEVEL BKN CLOUDS FROM THE FEATURE...WHICH
SHOULD LINGER MUCH OF SUNDAY.

SOME HINTS OF A THREAT FOR RIVER VALLEY FOG AT KLSE FOR SUN
MORNING...BUT A COUPLE THINGS GOING AGAINST IT. FIRST IS THE
MID/HIGH LEVEL CLOUDS EXPECTED OVERNIGHT - INHIBITING RADIATIONAL
COOLING. SECOND IS THE HRRR/RAP/NAM BUFKIT SOUNDINGS ALL INCREASE
THE LOW LEVEL WINDS JUST OFF THE DECK OVERNIGHT. THIS KIND OF
STIRRING DOES NOT PROMOTE DENSE FOG FORMATION. THAT SAID...COULD
STILL SEE A BKN STRATUS DECK DEVELOP...BUT AT THIS TIME...DON/T FEEL
ANY MENTION OF FG OR BKN CIGS ARE WARRANTED FOR KLSE. OBVIOUSLY IT
WILL BE MONITORED AND ADJUSTED IF NEED BE.

&&

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

$$

SHORT TERM...ROGERS
LONG TERM...ROGERS
AVIATION...RIECK



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