Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 262354
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
654 PM CDT TUE MAY 26 2015

.SHORT TERM...(TONIGHT THROUGH WEDNESDAY)
ISSUED AT 245 PM CDT TUE MAY 26 2015

UPPER LEVEL SHORTWAVE TROUGH/SFC LOW LIFTING NORTHEAST/EAST ACROSS
WI THIS AFTERNOON...AND WILL CONTINUE THEIR SLOW JAUNT TOWARD THE
EASTERN GREAT LAKES TONIGHT/EARLY WED. DEFORMATION/FRONTOGENETICALLY
FUELED REGION OF MAINLY SHOWERS NORTH-WEST OF THE SFC LOW WILL LIFT
NORTHEAST...WITH THE MESO MODELS KEEPING MUCH OF THE FORECAST AREA
NORTH OF I-90 ON THE WET SIDE THROUGH AT LEAST 06Z.

THE DRY DAY THAT WEDNESDAY PROMISED IS NOT LOOKING AS CLEAR CUT
ANYMORE. THE UPPER LEVEL TROUGH AXIS IS SLATED TO REST FROM
NORTHEAST WI INTO THE SOUTHERN PART OF THE BADGER STATE AT
12Z...WHILE A WEAKER PIECE OF ENERGY SLIDES DOWN ACROSS NORTHEAST
WI...INTO THE BASE OF THE TROUGH. THE MEAN TROUGH WILL SLIP OFF TO
THE EAST...BUT THE OTHER PIECE OF ENERGY SLIDES DOWN DURING THE
AFTERNOON - BRINGING SOME LOW LEVEL WARM ADVECTION WITH IT. THE NAM
AND GFS BUILD AS MUCH AS 2 K J/KG OF SBCAPE ACROSS WESTERN/CENTRAL
WI WED AFTERNOON...OUTSIDE OF THE DEPARTING RAIN/CLOUD SHIELD.
ENOUGH LIFT/SATURATION WITH THE SHORTWAVE THAT SOME ASSOCIATED
SHOWER/STORM CHANCES WILL BE NEEDED FOR AT LEAST THE I-94 CORRIDOR
TOMORROW AFTERNOON. POINTS WEST OF THERE SHOULD SEE AMPLE SUN...AND
SOME WARM...SUMMER-LIKE TEMPS AROUND 80.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 245 PM CDT TUE MAY 26 2015

MODELS REMAIN IN GOOD AGREEMENT WITH PROGRESSIVE ZONAL FLOW A LOFT
USHERING IN VARIOUS SHORTWAVE TROUGHS/RIDGES THROUGH THE EARLY PART
OF NEXT WEEK.

ONE TROUGH IS SLATED TO MOVE WEST-EAST ACROSS CANADA THIS
WEEK...WITH THE TROUGH AXIS/BULK OF UPPER LEVEL ENERGY SWINGING
NORTH OF THE UPPER MISSISSIPPI RIVER VALLEY FRIDAY NIGHT. ITS
ASSOCIATED SFC LOW IS WELL AHEAD OF THE TROUGH...BUT IT WILL DRAG A
COLD FRONT SOUTHWEST ACROSS THE REGION...LINKING UP WITH ANOTHER
LOW/TROUGH COMBO ACROSS THE SOUTHERN PLAINS. THE GFS BUILDS 2000+
J/KG OF SBCAPE FRI AFTERNOON AHEAD OF THE FRONT...WITH THE BULK OF
THE WIND SHEAR ALONG AND POST THE FRONT. BOTH THE EC AND GFS SUGGEST
A PERKY LINE OF CONVECTION IS POSSIBLE LATE FRI AFTERNOON/EVENING.
THAT SAID...SOME MORNING PCPN ALSO APPEARS PROBABLE FRIDAY...AND
WITH CLOUD COVER A QUESTION MARK...HOW MUCH INSTABILITY COULD DEVELOP
IS VERY UNCERTAIN. IT IS A TIME FRAME TO WATCH THOUGH...AS THERE IS
SOME POTENTIAL FOR STRONG-POSSIBLY SEVERE STORMS.

LATEST GFS RUN HAS NOW COME MORE IN LINE WITH THE EC THINKING FOR
SAT. BOTH SAG THAT FRONT SOUTH BY SAT MORNING...BUT THE GFS HAD
REMAINED ADAMANT WITH SLIPPING AN UPPER LEVEL SHORTWAVE ACROSS THE
REGION SAT MORNING...RIDING WEST-EAST NORTH OF THE SFC FRONT. THIS
WOULD RESULT IN A WET MORNING FOR MOST OF THE FORECAST AREA. NOW
TRENDS IN BOTH MODELS - PLUS THE GEM - ARE DRY. WILL PAINT THE
FORECAST THIS WAY.

THE WEEKEND IS LOOKING DRY...BUT RELATIVELY COOL WITH 850 MB TEMPS
GOING FROM 14 C AT 00Z SAT TO 6 C BY 00Z SUN.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 651 PM CDT TUE MAY 26 2015

A DRY SLOT IS MOVING NORTHWARD IN THE TAF SITES. AS THIS OCCURS...
EXPECT THE SHOWERS AND RAIN TO BECOME MORE SCATTERED BY 27.0130Z.
THIS WILL ALSO KEEP THE CEILINGS AROUND 2500 FEET AT KRST AND 3000
FEET AT KLSE. WILL HAVE TO WATCH CEILINGS BETWEEN 27.08Z AND
27.11Z AT KRST BECAUSE BOTH THE SIMULATED SATELLITE AND SOUNDINGS
SUGGESTS IFR/LIFR CEILINGS DURING THIS TIME. SUBSIDENCE IN THE
WAKE OF THE SYSTEM WILL CAUSE CLEARING AT BOTH TAF SITES AFTER
27.14Z.

&&

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

$$

SHORT TERM...RIECK
LONG TERM....RIECK
AVIATION...BOYNE



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