Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 281733
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1233 PM CDT MON JUL 28 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 316 AM CDT MON JUL 28 2014

MAIN FORECAST CONCERNS ARE CLOUD TRENDS TODAY.

LATEST INFRARED SATELLITE IMAGERY INDICATING STRATOCUMULUS CLOUDS
OVER MUCH OF MINNESOTA/EASTERN DAKOTAS AND MOSTLY CLEAR SKIES OVER
MUCH OF WISCONSIN. THIS CORRELATES WELL WITH THE LATEST 28.03Z RAP
850MB RELATIVE HUMIDITY FIELD AND THE 850MB 28.00Z UPPER AIR
ANALYSIS.

TODAY THE 28.00Z NAM/GFS AND 28.03Z RAP DIFFER ON THE EXTENT OF THE
850MB MOISTURE...WHERE THE NAM IS MORE WIDESPREAD AND THE GFS IS
LESS EXTENSIVE. THE LATEST 28.03Z RAP APPEARS TO HANDLE THE EXTENT
OF THE CLOUDS/MOISTURE BETTER AND HAVE TRENDED SKY COVER CLOSER TO
THIS FOR TODAY. THIS SUGGEST THE CLOUDS WILL DIMINISH ACROSS
SOUTHEAST MINNESOTA AND NORTHEAST IOWA EARLY THIS AFTERNOON.

SKIES SHOULD BE MOSTLY CLEAR TONIGHT ACROSS MUCH OF THE FORECAST AREA
...AS MODELS SHOW 850MB MOISTURE ERODES/ADVECTS SOUTH OF FORECAST
AREA.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 316 AM CDT MON JUL 28 2014

TUESDAY AND WEDNESDAY...REGION REMAINS UNDER THE INFLUENCE OF THE
UPPER LEVEL TROUGH OVER THE EASTERN UNITED STATES. THE 28.00Z
GFS/NAM/ECMWF SHOW A COUPLE OF WEAK IMPULSES TO TRACK OVER THE
EASTERN PARTS OF THE FORECAST AREA. THE 28.00Z GFS/NAM BUFKIT
SOUNDINGS EAST OF THE MISSISSIPPI RIVER INDICATE CAPE OF 300 TO
AROUND 350 J/KG BY 21Z TUESDAY AND COMBINED WITH STEEP LOW LEVEL
RATES OF 8-9 C/KM AND ATMOSPHERE COLUMN UNCAPPED...EXPECT SCATTERED
SHOWERS AND ISOLATED THUNDERSTORMS TO DEVELOP EAST OF THE
MISSISSIPPI RIVER LATE TUESDAY MORNING INTO THE AFTERNOON HOURS.

WITH LESS MOISTURE AND MUCH OF THE FORECAST AREA REMAINS CAPPED
PER BUFKIT SOUNDINGS...ANY SHOWERS AND ISOLATED THUNDERSTORMS
WILL BE FOCUSED OVER THE EXTREME EASTERN PARTS OF THE FORECAST
AREA WEDNESDAY AFTERNOON.

THURSDAY INTO SUNDAY...MAIN FORECAST CONCERNS ARE THE DIURNALLY
DRIVEN SHOWERS/ISOLATED THUNDERSTORM POSSIBILITIES THROUGH THE
PERIOD. THE 28.00Z GFS/ECMWF/GEM CONTINUE TO DIFFER ON STRENGTH OF
WEAK SHORTWAVE TROUGHS EMBEDDED IN THE NORTHERLY FLOW ALOFT. THE
28.00Z GEM/GFS IS MORE AMPLIFIED WITH SHORTWAVE TROUGH ON FRIDAY
THAN THE ECMWF. HENCE...PRODUCE HIGHER AMOUNTS OF QPF ACROSS MUCH OF
THE FORECAST AREA. DUE TO THE STRENGTH ISSUES WITH WEAK
IMPULSES...CONFIDENCE IN FORECAST WITH PRECIPITATION CHANCES
THURSDAY INTO SATURDAY REMAIN LOW. TEMPERATURES THROUGH MUCH OF
THIS PERIOD WILL REMAIN SLIGHTLY BELOW NORMAL...AS THE AREA
REMAINS UNDER COOL NORTHERLY FLOW ALOFT.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1233 PM CDT MON JUL 28 2014

VFR CONDITIONS EXPECTED AT KRST/KLSE THROUGH THE PERIOD WITH
NORTHERLY FLOW BOTH AT THE SURFACE AND ALOFT. DIURNAL CUMULUS
WITH BASES 5 TO 7 KFT WILL SCATTER OUT THIS EVENING...BUT THEN A
WEAK UPPER LEVEL WEATHER SYSTEM WILL DIP SOUTH BY 06Z. NOT
EXPECTING ANY SHOWERS WITH THIS FEATURE BUT WILL LIKELY BRING MORE
SCATTERED MID LEVEL CLOUDS. FOR TUESDAY...A MORE VIGOROUS SYSTEM
MOVES THROUGH AND IS EXPECTED TO GENERATE SHOWERS/STORMS AFTER
18Z. THE GREATER FORCING AND DYNAMICS LOOK TO BE EAST OF KRST/KLSE
BUT A SHOWER/STORM MENTION MAY BE NECESSARY FOR THE NEXT TAF
CYCLE AT KLSE.

&&

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

$$

SHORT TERM...DTJ
LONG TERM....DTJ
AVIATION.....ZT



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