Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 230943
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
540 AM CDT SAT AUG 23 2014

.UPDATED
ISSUED AT 540 AM CDT SAT AUG 23 2014

AREAS OF DENSE FOG HAVE DEVELOPED AGAIN EARLY THIS MORNING...MOSTLY
ACROSS CENTRAL PORTIONS OF WI. OBSERVATIONS AND CALLS TO AREA LAW
ENFORCEMENT INDICATE THAT THE THICK FOG IS WIDESPREAD...WITH A LOT
OF 1/4 MILE VISIBILITIES. HAVE ISSUED A DENSE FOG ADVISORY THROUGH
10 AM TO ACCOUNT FOR THE RELATED THREATS. POCKETS OF DENSE FOG ARE
LOCATED ACROSS THE REST OF THE FORECAST AREA...BUT DOES NOT APPEAR
TO BE WIDESPREAD AT THE MOMENT. WILL MONITOR AND EXPAND ADV IF
NECESSARY.

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 330 AM CDT SAT AUG 23 2014

SFC BOUNDARY LIES...MORE OR LESS...WEST EAST ACROSS SOUTHERN IA INTO
CENTRAL ILL EARLY THIS MORNING. AN UPPER LEVEL TROUGH WILL LIFT
NORTHEAST ACROSS THE NORTHERN PLAINS TODAY...AND SHOULD HELP GIVE
THIS BOUNDARY A SHOVE NORTH. MEANWHILE...THERE ARE SUGGESTIONS IN
THE MESO MODELS THAT AN MCV ASSOCIATED WITH THE CURRENT CONVECTION
OVER NEB WOULD TAKE NORTHEAST TRACK TODAY...AND COULD SERVE AS A
FOCUS FOR SHOWER/STORMS DEVELOP AS IT AND THE BOUNDARY SLIDE
NORTH/NORTHEAST ACROSS THE REGION.

HEAT AND HUMIDITY WILL ROUND OUT THE WEEKEND...AND HEAT ADVISORIES
LOOK LIKELY FOR PORTIONS OF THE REGION. 850 MB SREF TEMP ANOMALIES
AROUND +1.5 FOR SUNDAY WHILE 950 MB TEMPS ARE EXPECTED TO WARM TO 26-
28 C. HIGHS SHOULD REACH 90 ACROSS MUCH OF THE FORECAST AREA. ADD IN
DEW POINTS IN THE LOWER 70S AND AFTERNOON HEAT INDICES SHOULD REACH
100 FOR A LARGE PORTION OF THE FORECAST AREA.

.LONG TERM...(MONDAY THROUGH FRIDAY)
ISSUED AT 330 AM CDT SAT AUG 23 2014

MODELS IN PRETTY GOOD AGREEMENT WITH THE OVERALL PATTERN THROUGH
THE MIDDLE PART OF THE NEW WORK WEEK.

SOLUTIONS SUGGEST AN UPPER LEVEL SHORTWAVE WILL TRACK OUT OF THE
CENTRAL ROCKIES...ACROSS THE NORTHERN PLAINS AND INTO SOUTHERN
CANADA SUNDAY NIGHT. ITS ASSOCIATED SFC COLD FRONT WILL DRAG ACROSS
THE REGION LATE SUNDAY NIGHT INTO MONDAY...WITH THE SOUTHERN EXTENT
LIKELY LINGERING IN A SOUTHWEST-NORTHEAST ORIENTATION OVER THE
REGION. RIPPLES IN THE UPPER LEVEL FLOW WILL KICK OUT OF THE MEAN
TROUGH...AND WORK ON THIS BOUNDARY MON-TUE. THIS NEXT TROUGH THEN
SLIDES ACROSS THE UPPER MISSISSIPPI RIVER VALLEY WED
NIGHT/THU...CONTINUING TO WORK ON THAT SFC BOUNDARY...BUT ALSO
PUSHING IT EAST/SOUTHEAST AS THE SYSTEM EXITS INTO THE EASTERN GREAT
LAKES ON THU NIGHT.

THERE ARE SOME DISCREPANCIES IN THE MODELS WITH PLACEMENT...TIMING
AND STRENGTH OF THIS TROUGH...BUT THE TRENDS ARE SIMILAR AND ALL
POINT TO SEVERAL DAYS WITH RAIN CHANCES.

NOT OVERLY STRONG...BUT FAIRLY PERSISTENT FETCH OF 850 MB MOISTURE
TRANSPORT INTO THE REGION FOR THE EARLY PART OF THE UPCOMING WEEK.
WARM CLOUD DEPTHS CONTINUE TO HOVER NEAR 4 KFT WHILE PWS RANGE FROM
1.5 TO 1.75 INCHES. SO...HEAVY RAIN WOULD BE LIKELY WITH ANY
THUNDERSTORMS...ESPECIALLY THE STRONGER ONES.

AS FOR SEVERE POTENTIAL...AFTERNOON SBCAPES PROGGED FROM 2000-3000
J/KG PER THE GFS INTO WED...MOSTLY AROUND AND SOUTH OF THE SFC
BOUNDARY. HOWEVER...WITH LOW/MID LEVEL WARMING PERSISTING...AND 700
MB TEMPS AROUND 10 C...THERE WILL BE A CAP TO DEAL WITH...AND SOME
OF THIS LOW LEVEL INSTABILITY WILL NOT BE REALIZED. BUFKIT SOUNDINGS
INDICATE THIS TOO. THE DEEPER...STRONGER SHEAR IS EXPECTED TO BE
WELL INTO THE COLD AIR NORTH OF THE BOUNDARY...DISPLACED FROM THE
STRONGER INSTABILITY. THERE IS SOME OVERLAP...SO SOME ENHANCED
UPDRAFTS COULD BE SUPPORTED. OVERALL...NOT SURE THERE IS A TIME
PERIOD THAT STANDS OUT FOR AN ORGANIZED SEVERE THREAT AT THIS TIME.
THERE CERTAINLY COULD BE SOME SEVERE TO MARGINAL SEVERE
STORMS...PERHAPS MORE PULSEY IN NATURE. MUCH DEPENDS ON
BOUNDARY/SHORTWAVE INTERACTION AND TIME OF DAY. LOOK FOR UPDATES IN
THE HWO FOR THE LATEST THOUGHTS ON THE DAY TO DAY SEVERE POTENTIAL.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT
1147 PM CDT FRI AUG 22 2014

THE MAIN FOCUS IS ON THE POTENTIAL FOR FOG TONIGHT AND HOW MUCH THE
EXPANSIVE HIGH LEVEL CLOUD COVER WILL HOLD THE FOG BACK FROM
FORMING. THIS WIDESPREAD CLOUD COVER HAS KEPT TEMPERATURES FROM
FALLING MUCH THIS EVENING...BUT DEW POINT DEPRESSIONS REMAIN FAIRLY
LOW...SO AM EXPECTING THAT THE FOG WILL STILL FORM...JUST LATER THAN
PREVIOUSLY THOUGHT. SHOULD THE CLOUD COVER REMAIN AS THICK AS IT
CURRENTLY IS...THEN THERE MAY BE MORE CONCERNS THAT THE FOG DOES NOT
DEVELOP. DUE TO THIS UNCERTAINTY...BACKED OFF ON THE 1/4SM FOG AND
UPPED CONDITIONS A BIT. BEYOND THE FOG...QUESTIONS REMAIN ABOUT THE
NEXT ROUND OF CONVECTION THAT COULD COME THROUGH IN THE AFTERNOON AS
A LEAD IMPULSE MOVES INTO THE REGION. A BRIEF PERIOD OF
SHOWERS/STORMS WILL BE POSSIBLE WHICH COULD CAUSE CONDITIONS TO DROP
BACK DOWN TO MVFR/IFR.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...DENSE FOG ADVISORY UNTIL 10 AM CDT THIS MORNING FOR WIZ017-029-
     034-042>044-053>055-061.

MN...NONE.
IA...NONE.
&&

$$
UPDATE.......RIECK
SHORT TERM...RIECK
LONG TERM....RIECK
AVIATION.....HALBACH



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