Area Forecast Discussion
Issued by NWS La Crosse, WI

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
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 44 45 46 47 48 49 50

000
FXUS63 KARX 310435
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1125 PM CDT SUN AUG 30 2015

.SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 248 PM CDT SUN AUG 30 2015

VISIBLE SATELLITE EARLY THIS AFTERNOON SHOWS THE LOW CLOUDS OVER
THE AREA ARE BREAKING UP/CLEARING OUT MUCH QUICKER THAN WHAT
OCCURRED SATURDAY AFTERNOON. WITH THESE TRENDS...EXPECT THAT MOST
IF NOT ALL OF THE AREA WILL BECOME MOSTLY CLEAR THIS EVENING. THE
CONCERN THEN BECOMES WHETHER ANY FOG OR LOW CLOUDS WILL FORM AGAIN
OVERNIGHT. THE 30.12Z NAM FORECAST SOUNDINGS AGAIN SHOW SATURATION
OCCURRING AT THE SURFACE FOR THE VALLEY SITES. HOWEVER...THE WINDS
JUST ABOVE THE SURFACE ARE EXPECTED TO BE BLOWING PRETTY GOOD WITH
THE NAM SHOWING BETWEEN 20 AND 25 KNOTS AROUND 1500 FEET. THIS
SHOULD TEND TO KEEP THE FOG FROM FORMING BUT LEAD TO ANOTHER LOW
CLOUD DECK. NOT SURE HOW EXPANSIVE THE CLOUD DECK WILL BE SO FOR
NOW WILL INCREASE THE CLOUDS INTO THE 40 TO 50 PERCENT RANGE AND
LET THE EVENING SHIFT ADJUST AS NEEDED.

DAYTIME TEMPERATURES STILL LOOK LIKE THEY WILL BE ABOVE NORMAL TO
START THE WEEK. THE LOW LEVEL RIDGE AXIS WILL SLIP INTO THE OHIO
RIVER VALLEY WHICH WILL SET UP A SOUTHWEST FLOW OVER THE REGION.
925 MB TEMPERATURES ARE EXPECTED TO WARM TO AROUND 25C MONDAY AND
THEN COULD REACH THE 27C TO 29C RANGE TUESDAY. AT THE
SURFACE...HIGHS MONDAY SHOULD RANGE FROM THE LOWER TO MIDDLE 80S
WITH SOME UPPER 80S POSSIBLE IN THE VALLEYS AND LOOK FOR MIDDLE TO
UPPER 80S TUESDAY WITH LOWER 90S IN THE VALLEYS.

THERE LOOKS TO BE A SMALL THREAT FOR SOME RAIN TUESDAY NIGHT. A
WEAK SHORT WAVE TROUGH IS FORECAST TO COME ACROSS THE REGION...BUT
THE 30.12Z GFS SHOWS VERY LITTLE HEIGHT FALLS WITH THIS FEATURE.
A DISSIPATING SURFACE TROUGH SHOULD DRIFT INTO THE WESTERN PARTS
OF THE FORECAST AREA WITH SOME WEAK MOISTURE TRANSPORT OCCURRING
INTO THIS BOUNDARY AHEAD OF THE SHORT WAVE TROUGH. FORECAST
SOUNDINGS FOR KRST FROM THE GFS DO NOT INDICATE MUCH MOISTURE IN
THE COLUMN AND WHAT IS THERE IS ABOVE 10000 FEET. WILL CARRY JUST
A VERY SMALL CHANCE FOR SOME RAIN ACROSS THE WESTERN SECTIONS
FOR LATE TUESDAY NIGHT.

.LONG TERM...(WEDNESDAY THROUGH SUNDAY)
ISSUED AT 248 PM CDT SUN AUG 30 2015

VERY LITTLE PATTERN CHANGE IS EXPECTED TO OCCUR THROUGH THE UP
COMING WEEKEND. THE UPPER LEVEL RIDGE IS EXPECTED TO REMAIN
ANCHORED FROM THE LOWER MISSISSIPPI RIVER VALLEY THROUGH THE OHIO
RIVER VALLEY INTO THE NORTHEAST PART OF THE COUNTRY. THE LONG WAVE
TROUGH WILL TRY TO MOVE SLOWLY EAST FROM THE PACIFIC COAST INTO
THE CANADIAN ROCKIES AND PACIFIC NORTHWEST. THIS WILL MAINTAIN THE
SOUTHWEST FLOW ALOFT OVER THE UPPER MIDWEST WITH THE POSSIBILITY
OF SHORT WAVE TROUGHS COMING OUT OF THE LONG WAVE TROUGH AND
ACROSS THE REGION. THIS FAR OUT IN TIME...IT WILL BE EXTREMELY
DIFFICULT TO TIME ANY OF THESE WEAK WAVES SO WILL STICK WITH THE
MODEL CONSENSUS GRIDS AND SHOW SOME LOW RAIN CHANCES EACH DAY.
SOME HINTS THAT THERE COULD BE A BETTER CHANCE OF RAIN FOR THE UP
COMING WEEKEND IF A SURFACE BOUNDARY CAN WORK INTO THE AREA LIKE
THE GFS IS TRYING TO SHOW...BUT THE 30.12Z ECMWF SUGGESTS THIS
BOUNDARY COULD STAY TO THE WEST OF THE AREA.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1125 PM CDT SUN AUG 30 2015

LIGHT SFC WINDS...HIGH PRESSURE IN THE VICINITY...AND T/TD SPREAD
AROUND 2 F AT LATE EVENING ALL SUPPORT DENSE FOG IN THE RIVER VALLEY
AT KLSE. HOWEVER...THE DEPTH OF THE LIGHT WIND LAYER DOES NOT.
BUFKIT HRRR/RAP/NAM SOUNDINGS ALL POINT TO 10+ KTS OF WIND WITHIN A
COUPLE HUNDRED FEET OF THE SURFACE. THIS STIRRING GENERALLY
PRECLUDES DENSE FOG FORMATION IN THE VALLEY - OR AT LEAST ITS
ABILITY TO SPREAD. IN ADDITION...IT CAN WORK AGAINST A LOW STRATUS
LAYER DEVELOPING. HOWEVER...WITH WIDESPREAD LOW LEVEL SATURATION
ACROSS THE REGION...MVFR BR IS CERTAINLY POSSIBLE...AT KLSE AND
KRST.

AS FOR CIGS...HRRR/RAP INCREASE THE LOW SATURATION ACROSS THE
SOUTH...WHICH COULD MANIFEST AS LOW STRATUS AND/OR THICK FOG. LATEST
RUNS KEEP THIS STRATUS/FOG THREAT SOUTH OF THE TAF SITES...AND WILL
HAVE THE FORECAST FOLLOW SUIT.

IT WILL BE ANOTHER EARLY MORNING OF CLOSELY FOLLOWING
OBS/TRENDS...WITH UPDATES MADE IF NEEDED.

&&

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

$$

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


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