Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 280452
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1152 PM CDT SAT JUN 27 2015

.SHORT TERM...(TONIGHT THROUGH TUESDAY)
ISSUED AT 250 PM CDT SAT JUN 27 2015

GOOD MODEL CONSENSUS WITH DROPPING AN UPPER LEVEL SHORTWAVE TROUGH
OUT OF SOUTHERN CANADA TO ACROSS THE UPPER MISSISSIPPI RIVER VALLEY
OVERNIGHT. DECENT QG CONVERGENCE THROUGH THE LAYERS WITH THE
FEATURE...FAVORING MN/IA. SWATH OF 925-700 MB LEADS THE SHORTWAVE
IN...ALSO TAKING A MORE MN-IA TRACK. UPPER LEVEL JET STREAK WILL
ENHANCE THE AVAILABLE LIFT. AT THE SFC...AN ASSOCIATED NORTH-SOUTH
RUNNING FRONTAL BOUNDARY MOVES ACROSS EASTERN MN/IA BY 18Z SUN. NO
TAP TO GULF MOISTURE...BUT SOME 850 MB MOISTURE TRANSPORT - ALBEIT
FROM THE NORTHWEST - COMES WITH THE SHORTWAVE...WHILE PWS APPROACH
1.5 INCHES. CERTAINLY ENOUGH SATURATION TO FUEL THE LIKELY
SHOWER/STORMS CHANCES.

AS FOR ANY SEVERE RISK...THE GFS/NAM CONTINUE TO BUILD A THIN RIDGE
OF ABOUT 1500 SBCAPE ALONG/AHEAD OF THE FRONT. HOWEVER...THIS IS CO-
LOCATED WITH WHAT IS EXPECTED TO BE AN ACTIVE REGION OF
SHOWERS/STORMS. ITS UNCERTAIN WHETHER THESE VALUES ARE REALISTIC
GIVEN THIS LIKELIHOOD. WHATEVER INSTABILITY DOES DEVELOP WILL
ENHANCE THE COVERAGE...BUT BUFKIT SOUNDINGS PAINT A REALLY SKINNY
PROFILE TO THE CAPE...AND NOT SUPPORTIVE OF STRONG UPDRAFTS. SHEAR
IS ALSO MEAGER...MOSTLY IN THE 0-3KM LAYER AND AROUND 20 KTS.
THUS...SEVERE RISK LOOKS VERY LOW.

THE SHORTWAVE TROUGH WILL TAKE A RIGHT TURN EAST TOWARD THE EASTERN
GREAT LAKES AFTER IT SLIDES ACROSS THE FORECAST AREA...BUT ANOTHER
WEAKER RIPPLE FOLLOWS IN ITS WAKE FOR MONDAY. SBCAPES CLIMB TO
AROUND 1000 J/KG FOR THE AFTERNOON...WITH FAVORABLE LOW LEVEL LAPSE
RATES. SHOULD BE ENOUGH TO FIRE SCATTERED SHOWERS/STORMS...MOSTLY
AFTERNOON/EVENING. A SFC TROUGH COULD LINK THE SFC LOW FROM THE
SUNDAY CONVECTION WITH THE SFC LOW WITH THIS NEXT RIPPLE IN THE
FLOW. IF SO...THE BOUNDARY WOULD PROVIDE ANOTHER FOCUS FOR
SHOWER/STORMS DEVELOPMENT...WHICH COULD LINGER LONGER INTO MONDAY
NIGHT.

FOR TUESDAY...HIGH PRESSURE WILL BUILD IN FROM THE NORTH...AND LOOKS
TO BRING A MOSTLY DRY AND SUNNY DAY TO A BULK OF THE REGION. THAT
SAID...A COUPLE THINGS TO WATCH. FIRST IS HOW QUICKLY THE MONDAY
SYSTEM EXITS. IF ITS A BIT SLOWER...SOME RAIN CHANCES COULD LINGER
ACROSS THE FAR SOUTH/EAST. MEANWHILE...ANOTHER SHORTWAVE TROUGH
COULD STREAK IN FROM THE NORTHWEST LATER IN THE DAY. THE NAM FAVORS
SPINNING THIS ACROSS THE FORECAST AREA...WHILE THE GFS/EC KEEP IT TO
THE WEST. SIDING WITH THE GFS/EC IN THIS STEAD.

.LONG TERM...(WEDNESDAY THROUGH SATURDAY)
ISSUED AT 250 PM CDT SAT JUN 27 2015

NORTHWEST FLOW REMAINS IN CONTROL OF THE REGION/S WEATHER INTO NEXT
WEEKEND. THE GFS AND ECMWF BRING VARIOUS RIPPLES THROUGH THE
FLOW...ALTHOUGH THERE ARE SOME DIFFERENCES IN PLACEMENT AND TIMING.
THAT/S EXPECTED. THERE IS A GENERAL CONSENSUS IN THEIR LATEST RUNS
THAT THE BETTER RAIN CHANCES MAY SKIRT NORTH/SOUTH OF THE FORECAST
AREA. WEAK INSTABILITY EACH DAY TO TAP INTO...SO ANY BOUNDARY OR
SHORTWAVE SHOULD BE ABLE TO SPARK SOME SHOWER/STORMS. THAT
SAID...ORGANIZED SEVERE WEATHER DOES NOT LOOK LIKELY AT THIS TIME.
IN ADDITION...WHILE CONTINUING SMALL RAIN CHANCES EACH DAY DUE TO
MODEL DIFFERENCES ON WHERE/WHEN ON THE VARIOUS PERTURBATIONS COULD
SLIDE IN...THERE LOOKS TO BE A BETTER CHANCE THAN NOT FOR MOST AREAS
STAYING DRY INTO THE WEEKEND.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1152 PM CDT SAT JUN 27 2015

THE CONVECTION ACROSS MINNESOTA CONTINUES TO ADVANCE SOUTHEAST AND
HAS BEEN SLOWLY WEAKENING AS IT RUNS OUT OF THE BEST INSTABILITY.
WITH THE CURRENT MOVEMENT...EXPECT THIS TO START AFFECTING KRST
AROUND 07Z AND KLSE NEAR 09Z. THE CHANCE FOR THE RAIN SHOULD
PERSIST FOR ABOUT 3 TO 4 HOURS BEFORE IT MOVES PAST THE TAF SITES.
UP STREAM OBSERVATIONS SUGGEST THAT IT SHOULD COME THROUGH WITH
VFR CONDITIONS WITH CEILINGS AT MOST COMING DOWN TO THE 4 TO 5
THOUSAND FOOT RANGE. A BREAK SHOULD THEN OCCUR FOR MOST OF SUNDAY
MORNING BEFORE THE UPPER LEVEL LOW AND SHORT WAVE TROUGH START TO
MOVE OVER THE AREA. AS THIS OCCURS...ADDITIONAL DEVELOPMENT SHOULD
OCCUR. THE 28.00Z CR-NAM NEST...HI-RES ARW AND HI-RES NMM ALL
SUGGEST A LINE OF STORMS FORMING DURING THE AFTERNOON AND MOVING
ACROSS BOTH TAF SITES WHILE THE 28.01Z HRRR KEEPS THE ACTIVITY
WIDELY SCATTERED WITH NO ORGANIZATION. WITH A BIT MORE A BREAK
SUNDAY BEFORE REDEVELOPMENT...THE NAM BUFKIT SOUNDINGS SHOW AROUND
1000 J/KG OF CAPE IN THEM. CONFIDENT THAT THERE WILL BE
REDEVELOPMENT...JUST NOT CONFIDENT IN HOW MUCH WILL OCCUR AND
WHERE SO WILL STAY WITH A VCTS FOR NOW. THIS ACTIVITY SHOULD DIE
OFF EARLY SUNDAY EVENING AS THE SYSTEM MOVES PAST AND THE CAPE
STARTS TO DIMINISH.

&&

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

$$

SHORT TERM...RIECK
LONG TERM....RIECK
AVIATION...04



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