Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 071143
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
643 AM CDT MON JUL 7 2014

.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 250 AM CDT MON JUL 7 2014

IMMEDIATE CONCERN IS ON ANOTHER ROUND OF POTENTIALLY SEVERE STORMS
THIS AFTERNOON INTO THE EVENING.

BIG PICTURE WATER VAPOR IMAGERY SHOWS BROAD CYCLONIC FLOW ACROSS THE
NORTHERN TIER OF THE CONUS. SEVERAL EMBEDDED MID-LEVEL TROUGHS OF
NOTE...TROUGH NUMBER 1 MOVING SOUTHEAST OF THE AREA WITH A LINE OF
STORMS ACROSS NORTHERN IL INTO NORTHERN MO. TROUGH NUMBER 2 MOVING
ACROSS ND INTO WESTERN MN WITH A CLUSTER OF THUNDERSTORMS ASSOCIATED
WITH IT. AND...TROUGH NUMBER 3 DEEPENING ACROSS SOUTHERN
ALBERTA/NORTHERN MT. CLOSER TO HOME...SURFACE MAP HAS A SURFACE COLD
FRONT EXTENDING FROM EASTERN UPPER MI THROUGH SOUTHEAST WI...INTO
CENTRAL IA.

FOR TODAY...MODELS SHOW THE ND/MN TROUGH DAMPENING OUT THIS MORNING
AS THE WAVE OVER ALBERTA/MT CATCHES UP AND BECOMES THE DOMINANT MID-
LEVEL TROUGH BY THIS AFTERNOON. WARM AIR ADVECTION/ISENTROPIC LIFT
IN THE 850-700MB LAYER AHEAD OF THIS WAVE WILL BE SUFFICIENT FOR
SCATTERED SHRA/TS ACROSS MN...EVENTUALLY GETTING INTO OUR AREA BY
THIS AFTERNOON.

BY LATER THIS AFTERNOON AND INTO THE EVENING...PLAN ON THE TROUGH
AND A SURFACE COLD FRONT TO PUSH INTO THE AREA FOR AN UPTICK IN
THUNDERSTORM ACTIVITY. NAM INDICATING 0-3KM MUCAPE IN THE 2500-
3500J/KG RANGE WITH 0-1KM MLCAPE IN THE 1000-1500J/KG RANGE ALONG
WITH INCREASING 0-6KM SHEAR AS UPPER/MID LEVEL JET CORE NOSES IN.
THIS CAPE SEEMS A BIT HIGH GIVEN INVERTED-V/LOWER LEVEL MIXING LOOK
ENVIRONMENT IN THE BUFKIT SOUNDINGS. NAM/GFS INDICATING 0-6KM BULK
SHEAR INCREASING INTO THE 40-60KT RANGE IN THE 00-03Z TIME FRAME AS
THE FRONT PUSHES THROUGH. BOTTOM LINE...POTENTIAL IS THERE FOR A FEW
SUPERCELLS/BOWING LINE SEGMENTS AND ANOTHER ROUND OF POTENTIALLY
SEVERE THUNDERSTORMS FOR THE AREA BY LATER THIS AFTERNOON INTO THE
EVENING. SEVERE THREATS INCLUDE DAMAGING WIND...LARGE HAIL...AND AN
ISOLATED TORNADO OR TWO. HIGHEST SEVERE THREAT TIME APPEARS TO BE
BETWEEN 4 AND 10 PM.

LOOK FOR THE COLD FRONT AND BULK OF THIS THUNDERSTORM ACTIVITY TO
CLEAR THE AREA AFTER MIDNIGHT.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 250 AM CDT MON JUL 7 2014

FOR TUESDAY...LINGERING COOLER CYCLONIC FLOW ALOFT AND FAIRLY STEEP
LOW-MID LEVEL LAPSE RATE SHOULD BE SUFFICIENT FOR SCATTERED SHRA/TS
ACTIVITY...MAINLY ALONG AND EAST OF THE MISSISSIPPI RIVER. LOOK FOR
HIGHS IN THE 70S.

HIGH PRESSURE RIDGE BUILDS OVER THE AREA WEDNESDAY THROUGH THURSDAY
FOR A PERIOD OF DRY/PLEASANT WEATHER. LOOK FOR HIGHS BOTH DAYS IN
THE 70S...MAYBE A FEW LOWER 80S GOING INTO THURSDAY.

FOR THURSDAY NIGHT INTO FRIDAY...GFS/ECMWF SHOW ANOTHER SIGNIFICANT
MID-LEVEL TROUGH COMING DOWN FROM THE NORTHERN PLAINS INTO THE UPPER
MISSISSIPPI RIVER VALLEY FOR THE POTENTIAL OF AN MCS.

CYCLONIC/NORTHWEST FLOW ALOFT BECOMES DOMINANT FOR SATURDAY AND
SUNDAY  ALONG WITH A COUPLE EMBEDDED WAVES. TIMING A BIT DIFFICULT
TO NAIL DOWN AT THIS POINT...SO CONSENSUS POPS YIELD SMALLER-END
SHOWER/THUNDER CHANCES. OTHERWISE...LOOKS LIKE SLIGHTLY BELOW NORMAL
TEMPERATURES WITH HIGHS IN THE UPPER 70S/LOWER 80S.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 642 AM CDT MON JUL 7 2014

A WEATHER SYSTEM MOVING IN FROM THE DAKOTAS WILL WORK TOGETHER
WITH SOME INSTABILITY BUILDING IN THE AFTERNOON TO PROVIDE
SCATTERED COVERAGE OF SHOWERS AND THUNDERSTORMS. SOME OF THESE MAY
BE STRONGER. TIMING RIGHT NOW IS OF LOWER CONFIDENCE BUT THERE
SHOULD BE A WAVE OF SHOWERS/STORMS LATER IN THE AFTERNOON...THEN
POSSIBLY A WINDOW OF 2-3 HOURS BEFORE COVERAGE BEGINS TO INCREASE
AGAIN. DID NOT BUILD THIS BREAK INTO THE TAFS.

SOME OF THE STORMS COULD PROVIDE GUSTY WINDS TO 60 KTS. THE
WEATHER AND COLD FRONT SHIFT EAST AFTER 06Z WITH WHAT APPEARS TO
BE A LINGERING MVFR CLOUD DECK FOR A PERIOD.

&&

.HYDROLOGY...
ISSUED AT 250 AM CDT MON JUL 7 2014

THE MISSISSIPPI RIVER CONTINUES TO FALL. IN FACT...WE ARE EXPECTING
ALL THE RIVER FORECAST POINTS WITHIN THE ARX FORECAST AREA TO FALL
BELOW FLOOD STAGE BY THURSDAY FROM NORTH TO SOUTH. PERIODIC RAIN IS
FORECAST OVER THE NEXT FEW DAYS...BUT IT APPEARS THIS RAINFALL WILL
NOT BE ENOUGH TO HAVE A SIGNIFICANT IMPACT ON THE MISSISSIPPI...OR
ITS TRIBUTARIES FOR THAT MATTER. FOR THE CURRENT AND FORECAST RIVER
LEVELS...SEE OUR INTERNET PAGE AT WWW.WEATHER.GOV/LACROSSE.

&&

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

$$

LONG TERM...DAS
AVIATION...BAUMGARDT
HYDROLOGY...DAS


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