Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 240457
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1157 PM CDT SAT APR 23 2016

.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 329 PM CDT SAT APR 23 2016

AT 3 PM...A SURFACE WARM FRONT WAS LOCATED ALONG INTERSTATE 94.
TEMPERATURES SOUTH OF THIS INTERSTATE WAS IN THE MID AND UPPER
60S. MEANWHILE NORTH OF THIS INTERSTATE...TEMPERATURES RANGED FROM
THE MID 50S TO LOWER 60S.

THE 23.12Z AND 23.18Z MODELS ARE IN GENERAL AGREEMENT THAT THE
WARM FRONT WILL LAY UP JUST NORTH OF INTERSTATE 94 TONIGHT AND
REMAIN THERE THROUGH SUNDAY NIGHT. THIS WILL BE WHERE THE BEST
925 TO 850 MB MOISTURE TRANSPORT AND FRONTOGENESIS WILL BE
LOCATED. AS A RESULT...KEPT THE HIGHEST RAIN CHANCES LOCATED IN
THIS AREA.

WITH THE SURFACE AND MOST UNSTABLE CAPES NOT ARRIVING UNTIL
SUNDAY AFTERNOON...PULLED BACK ON THE THUNDERSTORM CHANCES SOME
AND LIMITED THEM TO NORTH CENTRAL WISCONSIN FOR TONIGHT AND SUNDAY
MORNING. WITH THE COLD FRONT MOVING INTO THE AREA AND LITTLE
CAPPING IN THE WARM SECTOR ON SUNDAY AFTERNOON AND NIGHT...
INCREASED THE THUNDERSTORM CHANCES ACROSS THE ENTIRE AREA.

LIKE THE PAST DAY...THE NAM CONTINUES TO HAVE HIGHEST
SURFACE AND MOST UNSTABLE CAPES FROM SUNDAY AFTERNOON AND NIGHT.
THE NAM HAS CAPES UP TO 1750 J/KG SOUTH OF INTERSTATE 94 ON SUNDAY
AFTERNOON AND EVENING. MEANWHILE THE GFS AND ECMWF ONLY HAVE
SURFACE AND MOST UNSTABLE CAPES UP TO 750 J/KG THROUGH THIS TIME
PERIOD. WHILE THERE IS SOME INSTABILITY...THE MAIN LIMITING
FACTOR FOR SEVERE WEATHER ON SUNDAY AFTERNOON AND EVENING WILL BE
THE SHEAR. THE MODELS CONTINUE TO SHOW THAT THE SHEAR IN THE WARM
SECTOR IS MAINLY CONFINED TO THE 0-3 KM LAYER AND REMAINS AT
30 KNOTS OR LESS. AS A RESULT...THE MAIN STORM MODE LOOKS TO LINE
SEGMENTS. HOWEVER IF THE INSTABILITY ENDS UP BEING A BIT HIGHER
NORTH OF INTERSTATE 94...THERE MAY BE AN ISOLATED ELEVATED
SUPERCELL.

WITH SOUTHERLY WINDS AHEAD OF THE APPROACHING SHORT WAVE TROUGH
AND SURFACE LOW...THE PRECIPITABLE WATER VALUES WILL GRADUALLY
INCREASE FROM 0.7 INCHES AT 24.00Z TO AROUND 1.3 INCHES BY
25.00Z. AS A RESULT...SOME OF THE SHOWERS AND THUNDERSTORMS MAY
PRODUCE BRIEF PERIODS OF HEAVY RAIN.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 329 PM CDT SAT APR 23 2016

ON MONDAY...A LOW PRESSURE AREA AND COLD FRONT WILL MOVE SOUTHEAST
THROUGH THE AREA. THE NAM HAS SURFACE AND MOST UNSTABLE CAPES
CLIMBING UP TO 3000 J/KG SOUTH OF INTERSTATE 90 IN THE EARLY
AFTERNOON. MEANWHILE THE GFS AND ECMWF ONLY HAVE THESE CAPES UP TO
750 J/KG. WHILE THERE IS SOME DISAGREEMENT ON THE CAPES...ALL 3
MODELS INDICATE THAT THERE WILL BE SUFFICIENT SHEAR FOR SUPERCELL
DEVELOPMENT. THIS OF COURSE IS HIGHLY DEPENDENT UPON WHETHER THE
MODELS ARE CORRECT ON SOME INSTABILITY BUILDING AHEAD OF THIS
FRONT. WE WILL HAVE TO WATCH THIS PERIOD CLOSELY.

FROM WEDNESDAY INTO WEDNESDAY NIGHT...A LOW PRESSURE SYSTEM WILL
MOVE SOUTH OF THE FORECAST AREA. WITH THE TRACK OF THIS SYSTEM
BEING A BIT FURTHER SOUTH THAN PREVIOUS RUNS...THE INSTABILITY
ACROSS THE AREA WILL LIKELY BE LESS THAN 250 J/KG. IN ADDITION...
THE DEEP SHEAR WILL BE SOUTH OF INTERSTATE 80. THIS WILL KEEP THE
THREAT OF SEVERE WEATHER SOUTH OF THE FORECAST AREA.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1157 PM CDT SAT APR 23 2016

SCATTERED SHOWERS ARE EXPECTED DURING THE OVERNIGHT HOURS. VFR
CONDITIONS  WILL CONTINUE THROUGH AT LEAST MID AFTERNOON SUNDAY.
PLAN ON INCREASING SOUTH/SOUTHEAST WINDS ON SUNDAY AT 10 TO 17
KTS...GUSTING TO AROUND 25 KTS AT TIMES. THE STRONGEST WINDS WILL
BE AT KRST. SHOWERS AND THUNDERSTORMS WILL MOVE INTO THE AREA
AFTER 00Z. HAVE ADDED VCTS TO THE TAFS FOR THE EVENING HOURS AND
WILL LIKELY HAVE TO GO WITH -TSRA SOON IF FORECAST MODEL TRENDS
CONTINUE.

&&

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

$$

SHORT TERM...BOYNE
LONG TERM...BOYNE
AVIATION...WETENKAMP



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