Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 232305
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
605 PM CDT WED JUL 23 2014

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 316 PM CDT WED JUL 23 2014

MAIN FORECAST CONCERNS IN THE SHORT TERM ARE ON VALLEY FOG
POTENTIAL AND LOW TEMPERATURES TONIGHT.

HIGH PRESSURE WILL BUILD INTO THE FORECAST AREA THIS EVENING AND
TONIGHT PROVIDING MOSTLY CLEAR SKIES AND COOL OVERNIGHT
TEMPERATURES. THE CLEAR SKIES AND COOL TEMPERATURES WILL SET THE
STAGE FOR AREAS OF FOG ALONG VALLEY LOCATIONS AND ACROSS CENTRAL
WISCONSIN CRANBERRY COUNTRY. AFTER THE FOG BURNS OFF THURSDAY
MORNING PLAN ON MOSTLY SUNNY SKIES ACROSS THE AREA WITH HIGH
PRESSURE IN CONTROL. WITH SOME LINGERING LOW LEVEL MOISTURE WILL
LIKELY SEE A FEW TO POSSIBLY SCATTERED CUMULUS CLOUDS AROUND. LOOK
FOR HIGH TEMPERATURES TO RANGE FROM THE MID 70S TO AROUND 80.
WINDS WILL SWING AROUND TO THE SOUTH TOMORROW AFTERNOON INTO
TOMORROW EVENING AS THE HIGH SLIDES EAST AND LOW PRESSURE
APPROACHES FROM DAKOTAS.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 316 PM CDT WED JUL 23 2014

THE LOW IS EXPECTED TO SLIDE SOUTHEAST THURSDAY NIGHT INTO FRIDAY
MORNING. 850 MB MOISTURE TRANSPORT FOCUSES INTO THE AREAS ALONG AND
WEST OF THE MISSISSIPPI RIVER THURSDAY NIGHT INTO FRIDAY MORNING. A
THUNDERSTORM COMPLEX LOOKS TO DEVELOP OVER EASTERN NORTH DAKOTA
THURSDAY EVENING THEN IS EXPECTED TO PUSH SOUTHEAST INTO THE UPPER
MISSISSIPPI RIVER VALLEY...WITH ADDITIONAL SHOWERS AND STORMS FIRING
AHEAD OF IT LATE IN THE NIGHT ON THE NOSE OF A STRENGTHENING LOW
LEVEL JET. THERE IS FAIRLY GOOD MODEL AGREEMENT THAT SHOWERS AND
STORMS WILL IMPACT SOUTHEAST MINNESOTA...NORTHEAST IOWA...AND
PORTIONS OF SOUTHWEST WISCONSIN LATE THURSDAY NIGHT INTO FRIDAY
MORNING. 0-3 KM MUCAPE VALUES LOOK TO RANGE FROM 1200 TO 2000 J/KG
LATE THURSDAY NIGHT INTO EARLY SATURDAY MORNING WITH 0-3 KM BULK
SHEAR VALUES OF 30 TO 45 KTS. THIS COULD SUPPORT THE POTENTIAL FOR
A FEW STRONG TO PERHAPS SEVERE THUNDERSTORMS. ALSO...PRECIPITABLE
WATER VALUES ARE FAIRLY HEALTHY RANGING FROM 1.5 TO 1.8. THE
PRECIPITABLE WATER VALUES COMBINED WITH WARM CLOUD DEPTHS OF 4 KM
SUGGEST THE STORMS WOULD BE EFFICIENT RAIN PRODUCERS AND MAY CAUSE
SOME CONCERNS ESPECIALLY IN URBAN AREAS. WITH THE RECENT DRY
WEATHER OVER THE REGION THE SOILS WOULD BE ABLE TO TAKE SOME RAIN
SO ANY HYDROLOGY CONCERNS WOULD HINGE ON PRECIPITATION RATE. WILL
HAVE TO KEEP A VERY CLOSE EYE ON THIS SYSTEM.

CHANCES FOR SHOWERS AND STORMS LINGER FRIDAY INTO FRIDAY NIGHT BUT
THEN WE SHOULD SEE A BREAK IN THE ACTIVITY ON SATURDAY AHEAD OF A
POTENT TROUGH DIVING SOUTH OUT OF CANADA. SATURDAY WILL BE A
SEASONABLY WARM DAY WITH HIGHS IN THE 80S. DEW POINTS IN THE MID
TO UPPER 60S WILL MAKE IT FEEL A LITTLE ON THE MUGGY SIDE BUT
OVERALL IS SHOULD BE A RATHER NICE LATE JULY DAY. THE TROUGH THEN
DIVES INTO THE UPPER MISSISSIPPI RIVER VALLEY SATURDAY NIGHT INTO
SUNDAY BRINGING SHOWERS AND THUNDERSTORMS TO THE AREA. A TROUGH
THEN SETS UP ACROSS THE REGION EARLY NEXT WEEK WITH TEMPERATURES
EXPECTED TO BE BELOW NORMAL. HIGHS ON MONDAY WILL BE RATHER
PLEASANT...RANGING FROM THE LOWER TO MIDDLE 70S. WEAK DISTURBANCES
MOVING THROUGH THE REGION IN THE NORTHERLY FLOW WILL BRING SLIGHT
CHANCES FOR SHOWERS AND STORMS TOWARDS THE MIDDLE PART OF THE
WEEK.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 605 PM CDT WED JUL 23 2014

DRY AIR ASSOCIATED WITH HIGH PRESSURE BUILDING INTO THE TAF SITES
THIS EVENING WILL GENERALLY ALLOW VFR CONDITIONS TO CONTINUE
THROUGH THURSDAY. HOWEVER...THERE IS CONCERN FOR VALLEY
FOG/STRATUS AT LSE...RESULTING FROM GOOD RADIATIONAL COOLING
CONDITIONS TONIGHT. THOSE ITEMS GOING AGAINST IT INCLUDE A
FAIRLY LARGE TEMPERATURE/DEWPOINT SPREAD AS OF 23Z OF 23F...THE
SHORTER LENGTH OF NIGHT COMPARED TO THE TYPICAL VALLEY FOG TIME IN
AUGUST/SEPTEMBER...AND LACK OF RAIN OVER THE PAST 10 DAYS. THESE
NEGATIVE ITEMS MAY PROMOTE MORE OF A STRATUS DECK VS FOG.
THEREFORE...ONLY CHANGE FROM THE 18Z LSE TAF WAS TO INCLUDE A BKN
LIFR CEILING IN THE 11-13Z TEMPO GROUP.

&&

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

$$

SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION...AJ


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