Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 250734
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
230 AM CDT MON AUG 25 2014

.SHORT TERM...(TODAY)
ISSUED AT 230 AM CDT MON AUG 25 2014

A COLD FRONT WAS SLIDING EASTWARD ACROSS THE REGION EARLY THIS
MORNING. LOW LEVEL MOISTURE TRANSPORT WAS FEEDING STORM
PRODUCTION...WITH AN AXIS OF 3K J/KG MUCAPE HELPING THE STORMS
ALONG. THE STORMS WILL PERSIST FOR A FEW HOURS PAST
DAYBREAK...FOCUSING MORE INTO NORTHEAST IA/SOUTHWEST WI WHERE THE
NOSE OF THE MOISTURE TRANSPORT WILL CO-LOCATE WITH UPGLIDE ON THE
305-315 K ISENTROPIC SFCS. RAP13/HRRR/HOPWRF MODEL RUNS PUSH THE
SHOWERS/STORMS EAST OF THE FORECAST AREA BY 15Z.

LATER IN THE AFTERNOON...SHOWERS AND STORMS COULD REDEVELOP ALONG
THE SAGGING BOUNDARY...BUT LIKELY EAST/SOUTH OF THE FORECAST AREA.

.LONG TERM...(TONIGHT THROUGH SUNDAY)
ISSUED AT 230 AM CDT MON AUG 25 2014

STILL LOOKING LIKE A PROLONGED PERIOD OF RAIN CHANCES...ALTHOUGH
LATEST MODEL SOLUTIONS HAVE SHIFTED THE HIGHER CHANCES SOUTHWARD.
KEY PLAYERS INCLUDE...

1) SURFACE FRONT. THE COLD FRONT THAT SLIDES ACROSS THE REGION TODAY
WILL EXTEND FROM NORTHEAST WI INTO SOUTHERN IA LATE
TONIGHT...GRADUALLY TAKING UP A MORE WEST-EAST ORIENTATION ACROSS
SOUTHERN IA/NORTHERN-CENTRAL ILL ON TUE. WITH THE UPPER LEVEL FLOW
WEAK AND MOSTLY ZONAL TO BROAD RIDGING...NOT A LOT OF IMPETUS FOR
THE FRONT TO MOVE. IT SHOULD FINALLY GET A PUSH EAST/SOUTHEAST
TOWARD THE UPCOMING WEEKEND AS AN UPPER LEVEL SHORTWAVE TROUGH
TRACKS EAST ACROSS THE CENTRAL PLAINS.

2) LOW LEVEL JET/MOISTURE TRANSPORT. NAM/GFS FOCUS THE NOSE OF THE
850 MB JET AND MAIN PUSH OF THE LOW LEVEL MOISTURE INTO EASTERN
NEB/WESTERN IA TONIGHT...TUE AND WED NIGHTS. EXPECT MCS ACTIVITY IN
THESE REGIONS...TRACKING EAST AROUND/ALONG THE SURFACE FRONT.

3) INSTABILITY AND WIND SHEAR. AFTERNOON SBCAPES IN EXCESS OF 4K
J/KG ALONG AND SOUTH OF THE BOUNDARY EXPECTED THROUGH THE WEEK.
INSTABILITY WEAKER AND ELEVATED NORTH OF THERE...WITH NOT ALL THAT
MUCH INDICATED VIA BUFKIT SOUNDINGS.

FOR WIND SHEAR...THE DEEPEST AND STRONGEST CONTINUES TO LIE IN THE
COLD AIR WELL NORTH OF THE FRONT...DISPLACED FROM THE FAVORABLE
INSTABILITY.

THE LIKELY RESULT FROM THIS IS THAT THE THREAT FOR ORGANIZED SEVERE
WEATHER IN THE FORM OF LARGE HAIL AND DAMAGING WINDS WILL BE
LIMITED. CERTAINLY COULD SEE A FEW STRONG TO POSSIBLY SEVERE STORMS
OVER THE NEXT FEW DAYS...BUT CURRENT SCENARIO DOESN/T SUPPORT A
SIGNIFICANT THREAT. HOWEVER...THERE COULD STILL BE HEAVY RAIN
IMPACTS. MORE ON THAT IN THE HYDROLOGY SECTION BELOW.

OVERALL...MOST OF THE RAIN THREAT WILL BE FOR NORTHEAST IA-SOUTHWEST
WI TONIGHT INTO WED NIGHT. THE RAIN CHANCES RETURN FOR THE ENTIRE
FORECAST AREA LATE WED NIGHT INTO FRIDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1051 PM CDT SUN AUG 24 2014

SHOWERS AND THUNDERSTORMS ARE LIKELY OVERNIGHT INTO MONDAY MORNING
AHEAD OF A COLD FRONT THAT CURRENTLY IS IN EASTERN MINNESOTA/CENTRAL
IOWA. A HIGHLY UNSTABLE AIR MASS AHEAD OF THIS FRONT SHOULD HELP TO
KEEP THIS LINE OF DEVELOPING THUNDERSTORMS GOING AS THEY TRACK TO
THE EAST OVERNIGHT WITH VISIBILITY LIKELY DROPPING DOWN TO IFR FOR A
BRIEF PERIOD. WINDS WILL THEN SHIFT AROUND TO THE WEST THIS
AFTERNOON ON INTO MONDAY NIGHT AS THE FRONT SLOWLY SHIFTS TO THE
EAST.

&&

.HYDROLOGY...
ISSUED AT 230 AM CDT MON AUG 25 2014

WARM CLOUD DEPTHS REMAIN IN THE 3.5-4KFT RANGE THROUGH THE WORK
WEEK...WITH PWS GENERALLY FROM 1.5 TO AS MUCH AS 2 INCHES. FAVORABLE
FOR EFFICIENT RAIN PRODUCERS. THE WEST-EAST RUNNING STATIONARY FRONT
MEANS TRAINING STORMS...AND COULD RESULT IN ROUNDS OF STORMS ACROSS
THE SAME LOCATIONS. WHERE THE BOUNDARY LIES IS KEY TO THE HEAVY RAIN
THREAT. LATEST MODEL SOLUTIONS HAVE SHIFTED IT A BIT FARTHER
SOUTH...TAKING THE MAIN AXIS FOR HEAVY RAIN SOUTH. HOWEVER...KICKER
SHORTWAVE FOR THU WILL FIRE SHOWERS/STORMS...AND HEAVY RAIN WOULD BE
LIKELY LOCALLY. OVERALL...THE THREAT FOR RIVER RISES AND FLASH
FLOODING FROM TRAINING STORMS/REPEATED ROUNDS OF RAINFALL LOOKS A
BIT LESS. STILL...NOT CONVINCED THERE IS NO THREAT AND TRENDS WILL
HAVE TO BE WATCHED THROUGH THE WEEK.

&&

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

$$

SHORT TERM...RIECK
LONG TERM....RIECK
AVIATION.....HALBACH
HYDROLOGY....RIECK



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