Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 012342
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
642 PM CDT MON JUN 1 2015

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 251 PM CDT MON JUN 1 2015

THE FOCUS WILL BE ON THE RAIN CHANCES TOWARD THE END OF THE
PERIOD.

HIGH PRESSURE CENTERED OVER LAKE SUPERIOR INTO ONTARIO WILL
REMAIN NEARLY STATIONARY THROUGH TUESDAY. THIS WILL MAINTAIN THE
DRY WEATHER WITH MOSTLY CLEAR SKIES FOR ANOTHER DAY. THE HIGH WILL
START TO SLOWLY MOVE AWAY FROM THE AREA TUESDAY NIGHT AND FULLY
MOVE OFF WEDNESDAY. THE HIGH WILL MOVE OFF AS THE NEXT STORM
SYSTEM STARTS TO APPROACH THE AREA FROM THE WEST. THE UPPER LEVEL
RIDGE AXIS WILL START TO GET FLATTENED TUESDAY WHICH WILL ALLOW A
SHORT WAVE TROUGH TO COME ACROSS THE UPPER MIDWEST WEDNESDAY AND
WEDNESDAY NIGHT. THE 01.12Z GFS SUGGESTS THIS WAVE WILL BE ABLE TO
PRODUCE SOME WEAK PV ADVECTION IN THE 500-300 MB LAYER AS IT COMES
ACROSS THE AREA. AS THIS WAVE MOVES IN...IT WILL PUSH A WEAK COLD
FRONT TOWARD THE AREA. THE WARM AIR ADVECTION AHEAD OF THE FRONT
IS EXPECTED TO PRODUCE 1 TO 3 UBAR/S OF UP GLIDE ON THE 305K
ISENTROPIC SURFACE. THE FRONTOGENESIS LOOKS TO BE WEAK WITH THIS
FRONT...BUT THE COMBINATION OF THE FORCING SIGNALS SHOULD BE
ENOUGH TO PRODUCE SOME SCATTERED CONVECTION ACROSS THE AREA. AT
THIS POINT...FEEL THE FORCING IS TOO WEAK TO GO MUCH ABOVE A 50
PERCENT RAIN CHANCE. WILL START TO BRING THE RAIN CHANCES INTO THE
WESTERN SECTIONS FOR LATE TUESDAY NIGHT AND THEN SPREAD THEM
ACROSS THEM EAST TO COVER ALL BUT THE FAR SOUTHEASTERN SECTIONS BY
WEDNESDAY AFTERNOON. THE SEVERE CHANCES WITH THIS ACTIVITY LOOKS
TO BE PRETTY LIMITED. THE BEST CAPE AXIS WILL REMAIN TO THE WEST
OF THE AREA CLOSER TO THE FRONT WITH THE FAR WESTERN SECTIONS
MAYBE HAVING AROUND 500 J/KG OF ML CAPE WEDNESDAY AFTERNOON. THE
SHEAR LOOKS TO BE LACKING THOUGH WITH ONLY 20 TO 25 KNOTS EXPECTED
IN THE 0-6KM LAYER.

.LONG TERM...(THURSDAY THROUGH MONDAY)
ISSUED AT 251 PM CDT MON JUN 1 2015

THE FIRST SHORT WAVE TROUGH WILL MOVE OUT OF THE REGION EARLY
THURSDAY TO BE QUICKLY FOLLOWED BY ANOTHER AND STRONGER WAVE. THE
GENERAL MODEL CONSENSUS AT THIS TIME IS FOR THIS WAVE TO COME UP
FROM THE SOUTHWEST AND TO BE INTENSIFYING AS IT COMES INTO THE
LOCAL AREA. THE PV ADVECTION IN THE 500-300 MB LAYER LOOKS TO BE A
LITTLE BETTER WITH THE GFS SUGGESTING THIS TO BE WEAK TO MODERATE
IN STRENGTH. THE SURFACE BOUNDARY THAT COMES IN WITH THE WAVE
WEDNESDAY WILL STILL BE HANGING AROUND THE AREA BUT AGAIN...THE
FRONTOGENESIS LOOKS TO BE PRETTY WEAK ALONG THIS BOUNDARY.
AGAIN...EXPECT THIS WILL BE ENOUGH TO PRODUCE SCATTERED CONVECTION
ACROSS THE AREA. THE SEVERE CHANCES COULD BE A LITTLE BIT BETTER
FOR THURSDAY AS THE MODELS SUGGEST THE CAPE AXIS SHOULD BE RIGHT
OVER THE AREA. STILL SOME UNCERTAINTY ON JUST HOW MUCH CAPE THERE
WILL BE WHICH WILL DEPEND ON IF OR HOW LONG OF A BREAK THERE WOULD
BE AFTER THE RAIN WEDNESDAY NIGHT. THE 01.12Z NAM SUGGEST UP TO
1500 J/KG OF SB CAPE COULD BE IN PLACE THURSDAY AFTERNOON...BUT
THE GFS IS NOT NEARLY AS ROBUST WITH 1000 J/KG OR LESS OF MU CAPE.
EITHER WAY...SHEAR WILL AGAIN BE AN ISSUE WITH 0-6KM SHEAR
EXPECTED TO BE 20 KNOTS OR LESS. THE RAIN CHANCES WILL CONTINUE
FRIDAY WITH THE SURFACE BOUNDARY STILL HANGING AROUND THE AREA
UNTIL THE SHORT WAVE TROUGH FINALLY MOVES OFF INTO THE OHIO RIVER
VALLEY. THE BOUNDARY WILL GET PUSHED OUT OF THE AREA WITH THIS
WAVE WHICH WILL ALLOW HIGH PRESSURE TO BUILD IN AND PROVIDE WHAT
SHOULD BE A DRY SATURDAY. ANOTHER SHORT WAVE TROUGH WILL QUICKLY
APPROACH IN THE NORTHERN STREAM RETURNING THE RAIN CHANCES BACK
TO THE AREA FOR SATURDAY NIGHT INTO MONDAY.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 642 PM CDT MON JUN 1 2015

SCATTERED HIGH CLOUDS FROM CONVECTION OVER THE ROCKIES WILL
CONTINUE TO SPILL INTO THE RIDGE OVER THE UPPER MISSISSIPPI RIVER
VALLEY. SUSTAINED SOUTHEAST AND SOUTH WINDS WILL REMAIN AROUND
10 KNOTS FOR MUCH OF THE TIME PERIOD. WITH DIURNAL HEATING ON
TUESDAY AFTERNOON...THE WINDS WILL GUST TO AROUND 20 KNOTS ON
TUESDAY AFTERNOON AT KRST.

&&

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

$$

SHORT TERM...04
LONG TERM...04
AVIATION...BOYNE



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