Area Forecast Discussion
Issued by NWS La Crosse, WI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43
000
FXUS63 KARX 231740
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1240 PM CDT SAT APR 23 2016

.SHORT TERM...(TODAY THROUGH MONDAY NIGHT)
ISSUED AT 316 AM CDT SAT APR 23 2016

PLENTY OF ACTIVE WEATHER POTENTIAL TO LOOK AT OVER THE NEXT FEW
DAYS...BUT FOR THE MOST PART...THE START OF THE WEEKEND TODAY LOOKS
PRETTY QUIET. A NICE COOL MORNING UNDERWAY OUT THERE WITH HIGH
PRESSURE NOSING DOWN INTO THE AREA FROM NEAR JAMES BAY...AND MAINLY
CLEAR SKIES/LIGHT WINDS SETTING THE STAGE FOR THE USUAL COOLER
BOG/LOW LYING AREAS OF THE EASTERN CWA TO TAKE A DIP DOWN INTO THE
UPPER 20S/LOWER 30S...WITH THE ONGOING FROST ADVISORY IN GOOD SHAPE
THROUGH 8 AM. HOWEVER...BIG CHANGES ARE AFOOT TO OUR WEST EARLY THIS
MORNING...WITH QUITE THE UPPER TROUGH PLOWING THROUGH THE WESTERN
CONUS...AND DOWNSTREAM HEIGHT FALLS ALREADY SETTING THE STAGE FOR
LEE CYCLONE DEVELOPMENT ACROSS EASTERN MONTANA. THAT LOW IS EXPECTED
TO REDEVELOP EASTWARD INTO SOUTH DAKOTA WITH TIME WHILE ALSO
STRENGTHENING...LIFTING A SURFACE AND ELEVATED WARM FRONT NORTH IN
OUR DIRECTION RIGHT ON THROUGH THE WEEKEND. DEEPENING SOUTHERLY FLOW
REGIME IN ADVANCE OF THE UPPER AND SURFACE LOW WILL STRENGTHEN
MOISTURE TRANSPORT INTO SAID WARM FRONT...LIKELY DELIVERING SEVERAL
ROUNDS OF SHOWERS AND STORMS ACROSS THE AREA. THE BIGGEST CHALLENGE
THROUGH THE FORECAST PERIOD REMAINS THE TIMING/PLACEMENT OF SAID
PRECIP...AS WELL AS AT LEAST SOME POTENTIAL FOR SEVERE STORMS...
PARTICULARLY SUNDAY NIGHT INTO MONDAY.

FIRST THINGS FIRST...NO BIG ISSUES FOR TODAY...THOUGH WILL HAVE TO
WATCH CONTINUED NORTHWARD EXPANSION OF FOG/STRATUS FROM IOWA WITHIN
RETURNING BOUNDARY LAYER MOISTURE. CAN ENVISION THIS (ESPECIALLY
STRATUS) BEING A PESKY ISSUE FOR THE MORNING HOURS BUT WITH TEMPS
RECOVERING THROUGH THE 60S THIS AFTERNOON WITH THICKENING MID AND
HIGH CLOUDS. CRANKING LOW LEVEL JET POINTING INTO THE REGION THIS
EVENING INTO TONIGHT SHOULD GET BALL ROLLING WITH SOME ELEVATED
CONVECTIVE DEVELOPMENT...WITH THE BEST MASS CONVERGENCE PROGGED TO
LAY OUT JUST TO OUR NORTH ACROSS NORTHERN WISCONSIN...THOUGH WILL
HAVE TO WATCH JUST WHERE THAT ELEVATED BOUNDARY LAYS OUT. ELEVATED
INSTABILITY IS NOTHING TOO IMPRESSIVE...WITH UP TO 500 J/KG AND
DECREASING QUICKLY WITH SOUTHEAST EXTENT THANKS TO STRONG CAPPING
HANGING TIGHT UP AROUND 750 MB. AS SUCH...WE MAY ULTIMATELY NOT SEE
A WHOLE LOT MORE THAN AN AGITATED ACCAS FIELD DOWN INTO NORTHEAST
IOWA AND FAR SOUTHERN WISCONSIN WITH MUCH BETTER COVERAGE UP INTO
CENTRAL WISCONSIN.

LOSS OF LOW LEVEL JET FORCING INTO SUNDAY MORNING MAY PUT THE KIBOSH
ON ANY ADDITIONAL PRECIP WITH A LACK OF ANY FORCING MECHANISMS...
WITH FOCUS SHIFTING TO THE AFTERNOON AND INTO SUNDAY NIGHT AS THE
UPPER LOW MAKES ITS APPROACH. LOOKING LIKE A PERIOD OF MODEST HEIGHT
FALLS/MID LEVEL DIFLUENCE WILL OVERSPREAD THE AREA FROM ABOUT 21Z
ONWARD THROUGH THE NIGHT...IN CONJUNCTION WITH ANOTHER GOOD PUSH OF
MOISTURE TRANSPORT TO DRIVE ANOTHER ROUND OF SHOWERS AND STORMS.
GOOD POOLED 900-800MB MOISTURE NEAR AN ELEVATED WARM FRONT SHOULD
DELIVER UPWARDS OF 500-1000 J/KG ELEVATED CAPE PER FORECAST RAOBS.
STILL SOME QUESTION ABOUT THE DEGREE OF EFFECTIVE SHEAR DURING THIS
STRETCH...WITH THE NAM/GFS A LITTLE DIFFERENT ON PLACEMENT/STRENGTH
OF THE UPPER WAVE AND PRECEDING MID LEVEL JET. HOWEVER...WITH
EXCELLENT AGREEMENT THAT THE SURFACE WARM FRONT/BACKED FLOW REGIME
WILL LIFT TO THE VICINITY OF THE I-90 CORRIDOR AND HINTS OF
EFFECTIVE SHEAR 30-40 KNOTS...WILL REALLY HAVE TO WATCH THE SUNDAY
AFTERNOON PERIOD FOR AT LEAST SOME SEVERE POTENTIAL.

COULD SEE ANOTHER SMALL POTENTIAL FOR SOME SEVERE ON MONDAY AS THE
UPPER LOW AND SURFACE WAVE WORK THROUGH AREA THOUGH CONFIDENCE IN
THE DETAILS AT THIS JUNCTURE REMAINS LOW AS THERE WILL NO DOUBT BE
SOME CONVECTIVE CONTAMINATION TO WARM FRONT PLACEMENT BY MONDAY
MORNING. OUTSIDE OF THE OUTLIER NAM SOLUTION...DEEP SHEAR AROUND 30
KNOTS AND ENHANCED LOW LEVEL SHEAR NEAR THE WARM FRONT (WHEREVER
THAT ENDS UP) COULD LEAD TO SOME LINE SEGMENTS IN ADVANCE OF THE
ENCROACHING COLD FRONT...BUT IT`S A MATTER OF AVAILABLE INSTABILITY.
ON THE OTHER HAND...SHOULD THE SLOWER NAM SOLUTION HOLD TRUE...A
MORE ROBUST SUPERCELL THREAT COULD BE PRESENT...THOUGH AGAIN THIS
REMAINS AN OUTLIER SOLUTION FOR THE MOMENT. LOOKING MUCH COOLER WITH
SOME SHOWERS BY MONDAY NIGHT AS THE STORM THREAT ENDS AND SOME
SHALLOW BUT CHILLY AIR SPREADS SOUTH THROUGH THE AREA.

.LONG TERM...(TUESDAY THROUGH FRIDAY)
ISSUED AT 316 AM CDT SAT APR 23 2016

LET THE ACTIVE WEATHER CONTINUE. FOR THE MOMENT...LOOKING DRY AND
ON THE COOLER SIDE FOR TUESDAY/TUESDAY NIGHT AS RATHER STRONG
HUDSON BAY RIDGING WORKS INTO THE AREA. IN FACT...THERE COULD BE
ANOTHER FROST THREAT IN SOME AREAS WITH SOME VERY DRY AIR
ARRIVING. HOWEVER...THAT HIGH LOOKS TO QUICKLY DEPART INTO MIDWEEK
WITH THE NEXT WESTERN UPPER TROUGH LIFTING THROUGH THE CENTRAL
PLAINS AND DRIVING ANOTHER LOW PRESSURE SYSTEM NEARBY. CONFIDENCE
ON THE EXACT DETAILS REMAINS LOW AT THIS POINT...BUT PER GUIDANCE
TRENDS THE PAST FEW DAYS...IT APPEARS WE WILL BE IN FOR ANOTHER
BOUT OF RAIN LATER WEDNESDAY INTO THURSDAY...WITH THUNDER ALSO
QUITE POSSIBLE PENDING THE DEGREE OF INSTABILITY THIS FAR NORTH.
CAN`T TOTALLY RULE OUT A SEVERE THREAT AT SOME POINT
EITHER...THOUGH THE BETTER RISK FOR THAT APPEARS TO BE FROM THE
SOUTHERN PLAINS THROUGH THE MID MISS VALLEY...WHILE WE MAY
ULTIMATELY END UP WELL NORTH OF THE SURFACE WARM FRONT AND
POTENTIALLY ON THE COOL SIDE TEMPERATURE-WISE. PLENTY OF TIME TO
WATCH THOSE DETAILS UNFOLD OVER THE COMING DAYS...WITH MORE THAN
ENOUGH ACTION TO DEAL WITH OVER THE NEXT HANDFUL OF DAYS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1240 PM CDT SAT APR 23 2016

VFR CONDITIONS WILL BE THE RULE AT KRST/KLSE THROUGH 24.18Z WITH
PERIODS OF AFTERNOON CUMULUS IN THE 3000 TO 4000 FT AGL LAYER...
GIVING WAY TO INCREASING MID-LEVEL CLOUDS THIS EVENING AND
OVERNIGHT. ANY SHOWER ACTIVITY TONIGHT IS EXPECTED TO REMAIN
MAINLY NORTH OF I-94...KEEPING TAF AIRFIELDS DRY. SOUTHERLY WINDS
WILL CONTINUE...GUSTING INTO THE MID 20 KT RANGE AT KRST THROUGH
THE AFTERNOON. EXPECT A STRONG LOW-LEVEL JET TO DEVELOP TONIGHT
ACROSS EASTERN SD INTO CENTRAL MN...SO ADDED A WIND SHEAR
COMPONENT AT KRST FROM 24.05Z TO 24.13Z WITH UP TO 45 KTS AROUND
1500 FT AGL.

&&

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

$$

SHORT TERM...LAWRENCE
LONG TERM...LAWRENCE
AVIATION...ROGERS



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.