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 232009
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
309 PM CDT SAT AUG 23 2014

.SHORT TERM...(TONIGHT THROUGH SUNDAY NIGHT)
ISSUED AT 309 PM CDT SAT AUG 23 2014

SHORT TERM MAIN CONCERN IS INCREASING HEAT SUNDAY.

WATER VAPOR/RAP 500MB ANALYSIS THIS AFTERNOON HAVE A MID-LEVEL
SHORTWAVE AND ASSOCIATED BAND OF SHOWERS/THUNDERSTORMS PER RADAR
MOSAIC ROTATING THROUGH SOUTHWEST WI/NORTHERN IL. CLOUD COVER AND
SCATTERED PRECIPITATION KEEP TEMPERATURES IN THE 70S...BUT WITH VERY
HUMID AIRMASS IN PLACE...FEELING MORE LIKE THE 80S.

FOR TONIGHT...LOW PRESSURE MOVING NORTHEAST OUT OF THE CENTRAL HIGH
PLAINS INTO THE NORTHERN PLAINS WILL DRAG A WARM FRONT NORTHWARD
THROUGH THE REGION. STILL A CHANCE OF A FEW SHOWERS AND
THUNDERSTORMS ALONG THE FRONTAL BOUNDARY...MAINLY ALONG/NORTHEAST OF
I-94 AS EASTERN FLANK OF 850MB MOISTURE TRANSPORT IMPINGES UPON IT.
OTHERWISE...WILL LIKELY SEE SOME STRATUS DEVELOPMENT TONIGHT IN
MOIST SOUTHERLY FLOW. ANY DENSE FOG POTENTIAL LOOKS MINIMAL AT THIS
POINT GIVEN STRENGTHENING SOUTHERLY FLOW TO KEEP THE LOWER BOUNDARY
LAYER SOMEWHAT MIXED. LOOK FOR LOWS TONIGHT IN THE MID/UPPER 60S
ACROSS CENTRAL WI...AND LOWER 70S ELSEWHERE.

LOOKS LIKE THE HEAT IS ON FOR SUNDAY AS WE WILL BE IN THE
WARM/CAPPED WARM SECTOR OF THE NORTHER PLAINS LOW. NAM STILL SHOWING
925MB TEMPERATURES IN THE 28-30C RANGE WEST OF THE MISSISSIPPI AND 25-
28C RANGE ACROSS THE EAST. AFTER SOME INITIAL MORNING
STRATUS...EXPECTING SUNSHINE AND THIS HOT SOUTHERLY FLOW TO PUSH
HIGHS INTO THE MID/UPPER 80S ACROSS CENTRAL WI...AND IN THE LOWER
90S IN THE WI RIVER VALLEY AND AREAS ALONG AND WEST OF THE
MISSISSIPPI RIVER. WITH DEW POINTS IN THE 70-75 DEGREE
RANGE...LOOKING AT HEAT INDICES IN THE 95 TO 105 DEGREE RANGE. AFTER
COLLABORATION WITH SURROUNDING OFFICES AND CRITERIA
CONSIDERATIONS...WILL HOLD OFF ON HEAT HEADLINE FOR NOW AND WILL
CONTINUE TO CONVEY CONCERN VIA OUR HAZARDOUS WEATHER OUTLOOK
AND WEATHER STORY/GRAPHIC PRODUCTS.

A COLD FRONT WILL THEN PUSH INTO THE AREA SUNDAY NIGHT FOR THE
LIKELIHOOD OF THUNDERSTORMS. CANNOT RULE OUT A SEVERE CHANCE GIVEN
HIGHER CAPE ENVIRONMENT AND SUFFICIENT 0-3KM BULK SHEAR IN THE 20-
30KT RANGE. WILL HAVE TO KEEP A CLOSE EYE ON THIS.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 309 PM CDT SAT AUG 23 2014

MEDIUM RANGE MODELS REMAIN IN PRETTY GOOD AGREEMENT WITH FRONTAL
BOUNDARY LINGERING ACROSS THE REGION THROUGH AT LEAST THURSDAY.
MODELS SHOW SEVERAL MID-LEVEL IMPULSES WORKING ON THIS FRONTAL
BOUNDARY FOR CONTINUED SHOWER/THUNDERSTORM CHANCES. WITH PRECIPITABLE
WATER VALUES REMAINING IN THE 1.5-2 INCH RANGE...WILL HAVE TO KEEP
AN EYE ON REPETITIVE CONVECTION POTENTIAL/POSSIBLE LOCALIZED
FLOODING. OTHERWISE...WITH CLOUD COVER AND GOOD CHANCES OF SHOWERS
AND STORMS...PLAN ON HIGH TEMPERATURES STARING OFF IN THE 80-90
DEGREE RANGE MONDAY...COOLING INTO THE LOWER/MIDDLE 70S BY THURSDAY.

SOME TIMING DIFFERENCES THEN ARISE BETWEEN THE GFS AND ECMWF FOR
FRIDAY AND SATURDAY. BOTH MODELS MOVE A MORE VIGOROUS MID-LEVEL
TROUGH THE REGION. GFS IS MUCH FASTER/PROGRESSIVE WITH THIS FEATURE
COMPERED TO THE ECMWF. AT THIS POINT...WILL TAKE A CONSENSUS
APPROACH WHICH YIELDS SMALLER-END SHOWER/THUNDERSTORM CHANCES WITH
HIGHS IN THE 70S.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1201 PM CDT SAT AUG 23 2014

THE SHOWERS AND STORMS CONTINUE TO ADVANCE NORTHEAST ACROSS THE
AREA BUT ARE NOW SHOWING A DIMINISHING TREND. EXPECT THAT THESE
WILL BE PAST KRST BY 18Z BUT WILL LINGER INTO THE EARLY AFTERNOON
WITH SOME MVFR CONDITIONS AT KLSE. ONCE THESE MOVE
THROUGH...EXPECT THAT BOTH SITES WILL HAVE VFR CONDITIONS AS A
WARM FRONT APPROACHES AND THEN MOVES THROUGH SWINGING THE WINDS
AROUND TO THE SOUTHEAST. HOWEVER...NO DECREASE IN THE LOW LEVEL
HUMIDITY LEVELS WILL OCCUR WHICH SHOULD PRESENT THE POSSIBILITY OF
IFR CEILINGS WITH LOW STRATUS AGAIN TONIGHT. THE FORECAST
SOUNDINGS FROM THE 23.12Z NAM AND 23.15Z RAP BOTH INDICATING THE
STRATUS SHOULD FORM AND HAVE INCLUDED IT IN BOTH FORECASTS. NOT
OVERLY CONCERNED ABOUT FOG FOR TONIGHT AS BOTH THE SURFACE WINDS
AND WINDS JUST ABOVE THE SURFACE SHOULD BE TOO STRONG WITH TOO
MIXING TO ALLOW IT TO FORM.

&&

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

$$

SHORT TERM...DAS
LONG TERM....DAS
AVIATION...04



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