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000
FXUS63 KARX 220431
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1131 PM CDT TUE MAY 21 2013

.SHORT TERM...(TONIGHT THROUGH FRIDAY NIGHT)
ISSUED AT 234 PM CDT TUE MAY 21 2013

UPPER LOW WILL HAVE AT LEAST ANOTHER DAY OF IMPACT FOR THE
CENTRAL US. WHILE SEVERE THUNDERSTORM THREAT IS OVER...FOCUS WILL BE
ON RAIN CHANCES UNTIL WE ARE CLEAR OF THIS SYSTEM. IN ADDITION...
MAY HAVE SOME LIMITED FROST /YES...FROST/ TO DEAL WITH LATE IN THE
WEEK.

UPPER LOW CONTINUES TO SPIN ALONG SOUTH DAKOTA AND MINNESOTA BORDER
THIS AFTERNOON. QUASI-STATIONARY MOVEMENT CONTINUES TO FORM
CONVECTION MAINLY ACROSS NORTHERN HALF OF WISCONSIN WHERE SLIGHTLY
HIGHER DEW POINTS ARE CREATING SOME MLCAPE. LOWER DEW POINTS BACK TO
THE SOUTHWEST MAY LIMIT ANY FORMATION GOING INTO THE EVENING.
MEANWHILE COOL CONVEYOR BELT OF PRECIPITATION ALSO WRAPPING AROUND
LOW BACK INTO THE DAKOTAS WITH LIGHT RAIN SHIELD.

WOULD THINK HIGHEST RISK FOR ANY ADDITIONAL SPOTTY SHOWERS GOING
INTO TONIGHT WILL BE NORTH OF INTERSTATE 90 AHEAD OF LOW...
BUT AS UPPER LOW APPROACHES WEDNESDAY...OVERALL RAIN THREAT SHOULD
BE ON THE RISE AREA WIDE. HAVE EVEN INCREASED RAIN CHANCES ON
WEDNESDAY AS UPPER LOW BEGINS TRANSITION INTO MORE OF AN OPEN WAVE
AND WESTERLIES MOVE IT EAST. HIGH TEMPERATURES WILL EVEN BE COOLER
ON WEDNESDAY AS LOW MOVES OVERHEAD. WOULD NOT BE SURPRISED IF SOME
LOCALES MISS THE 60 DEGREE MARK.

SHORT TERM RIDGE BUILDS IN FOR PROMISED COOLER AND DRIER DAY
ON THURSDAY...EVEN AS SUNSHINE PREVAILS. LOCATION OF RIDGE AXIS
EARLY FRIDAY MORNING COULD SETUP A BRIEF FROST THREAT...ESPECIALLY
IN CENTRAL WISCONSIN /FAVORED COOLER SPOTS/ WHERE LOWS COULD REACH
MID 30S.

MEDIUM RANGE GUIDANCE STILL SUGGESTING WARM FRONT RETURN BY END OF
THE WEEK COULD BE ENOUGH TO GENERATE A FEW THUNDERSTORMS BUT QUITE A
BIT OF UNCERTAINTY EXISTS THAT FAR OUT WITH TREND TO BUILD MEAN
UPPER RIDGE OVER NATIONS MID-SECTION THROUGH WEEKEND. SHOULD ALSO BE
A GRADUAL WARMING TREND.

.LONG TERM...(SATURDAY THROUGH TUESDAY)
ISSUED AT 234 PM CDT TUE MAY 21 2013

LOTS OF ATTENTION ON HOLIDAY WEEKEND FORECAST. MEDIUM RANGE GUIDANCE
HAS BEEN HINTING AT BUILDING OF UPPER RIDGE BUT DIFFER IN HANDLING
OF POSSIBLE CONVECTION ALONG WARM FRONT THAT SHOULD EXTEND FROM THE
DAKOTAS INTO ILLINOIS. LAST FEW ECMWF RUNS KEEP DRIER REGIME WITH
MINIMAL RAIN THREATS UNTIL TUESDAY WHEN SHORT WAVE ENERGY EJECTING
OUT OF WESTERN US TROUGH COMES IN. GFS SOLUTIONS KEEP THREAT FOR
RAIN CLOSER TO OUR AREA...BUT EVEN THAT SHOULD NOT TRANSLATE INTO
ALL DAY RAINS.

WOULD NOT BE SURPRISED IF RAIN CHANCES TREND DRIER AS WE GET
CLOSER...BUT FOR NOW WILL KEEP SMALL RAIN THREATS IN FOR THE
WEEKEND. AGAIN...SHOWERS OR STORMS WOULD BE INTERMITTENT AT WORST
WITH A HIGHER THREAT ACROSS IOWA AND LOWER CHANCES INTO NORTH OR
CENTRAL WISCONSIN.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1131 PM CDT TUE MAY 21 2013

THE MAIN FOCUS AT THE TAF SITES IS WITH THE POTENTIAL FOR MVFR TO
IFR FLIGHT CONDITIONS AND RAIN SHOWERS AS A LOW PRESSURE SYSTEM
MOVES THROUGH THE REGION. THIS LOW IS CURRENTLY TO THE NORTHWEST
OF THE REGION BUT IS STARTING TO SINK TO THE SOUTHEAST. ALL OF THE
MVFR TO IFR CEILINGS ARE CURRENTLY TO THE NORTH AND WEST OF THIS
LOW AND ARE EXPECTED TO GET INTO THE REGION LATER WEDNESDAY
MORNING. THE EXACT TIMING OF THAT IS IN DOUBT...BUT RST SHOULD SEE
SOME IFR CEILINGS MOVE IN AROUND DAYBREAK WITH MVFR POSSIBLE INTO
LSE AROUND THE SAME TIME. SOME SHOWERS ARE EXPECTED TO DEVELOP IN
THE MORNING HOURS AS WELL AND LAST THROUGH MUCH OF THE DAY BEFORE
DIMINISHING IN THE EVENING HOURS.

&&

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

$$

SHORT TERM...SHEA
LONG TERM....SHEA
AVIATION...HALBACH