Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 281121
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
621 AM CDT SUN SEP 28 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 240 AM CDT SUN SEP 28 2014

A VERY NICE END TO THE WEEKEND AS ANOTHER WARM AND SUNFILLED DAY IS
EXPECTED. 500 MB NAEFS HEIGHT ANOMALIES STILL RUNNING AROUND +1. 850
MB TEMPS GOING TO BE MUCH LIKE YESTERDAY...NEAR 14 C...AND EXPECT
HIGHS TO BE SIMILAR TO SATURDAY/S.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 240 AM CDT SUN SEP 28 2014

WETTER...COOLER PATTERN CHANGE AS THE UPPER LEVEL FLOW BECOMES MORE
ACTIVE AS THE RIDGE BREAKS DOWN AND TROUGHS TAKE AIM ON THE UPPER
MISSISSIPPI RIVER VALLEY.

FIRST FEATURE OF CONCERN IS A SHORTWAVE TROUGH TRACKING SOUTHEAST
ACROSS CANADA. NAM/GFS/ECMWF TRENDS CONTINUE TO DRAG THIS FEATURE
ACROSS THE NORTHERN GREAT LAKES AND OFF TO THE SOUTHEAST MON/MON
NIGHT. A WEST-EAST RUNNING SFC FRONT WILL SAG SOUTHWARD ACROSS THE
REGION WITH THE SHORTWAVE. THERE IS SOME FRONTOGENETIC RESPONSE WITH
THE BOUNDARY...BUT THE GFS WEAKENS WESTERN EXTENT OF THE FRONT AS IT
MOVES UNDER A SHORTWAVE RIDGE JUST WEST OF THE TROUGH. THE NAM HANGS
ONTO A BIT OF FORCING...BUT IS A LITTLE DISJOINTED. MEAGER 850 MB
MOISTURE TRANSPORT POINTS INTO THE TROUGH BUT THE GFS AND NAM BOTH
BUILD ABOUT 500-1000 J/KG OF MUCAPE AHEAD OF THE FRONT. WITH THE
BULK OF THE UPPER LEVEL SUPPORT TO THE EAST...AND RIDGING A LOFT TO
DEAL WITH...FEEL THE WESTERN FLANKS OF THE SFC BOUNDARY WILL HAVE A
HARD TIME SPARKING CONVECTION. IT CAN/T BE COMPLETELY RULED
OUT...BUT WILL KEEP MOST OF THE RAIN CHANCES AROUND THE I-94
CORRIDOR NORTH/EAST WHERE A BETTER MIX OF VARIABLES FOR RAIN
PRODUCTION ARE ANTICIPATED.

MODELS HAVE STAYED REMARKABLY CONSISTENT WITH TAKING A CLOSED 500 MB
LOW OVER THE WEST COAST...LIFTING IT INTO THE NATION/S MID-SECTION
BY 12Z TUE...AND THEN INTO SOUTHERN CANADA BY 12Z WED. MOST OF THE
UPPER LEVEL ENERGY WITH THE TROUGH STAYS ACROSS THE PLAINS...BUT IT
WILL WORK ON THE LEFTOVER SFC FRONT FROM THE PREVIOUS DAY AS IT
SWEEPS IN WITH ITS OWN WARM FRONT. WITH SOME LOW LEVEL MOISTURE
TRANSPORT FOR FUEL...EXPECT A WARM AIR ADVECTIVE/FRONTOGENETIC BAND
OF PCPN TO SWEEP IN FROM THE SOUTHWEST OVERNIGHT TUE...SLIDING
EASTWARD ACROSS THE FORECAST AREA ON WED.

AS THE TROUGH LIFTS NORTH-NORTHEAST INTO CANADA...THE EASTWARD PUSH
OF THE SFC FRONT WILL SLOW. THIS WILL ALLOW FOR A SHORTWAVE TROUGH
SWINGING AROUND THE BACKSIDE OF THE DEPARTING TROUGH TO INTERACT
WITH THE FRONT. MODELS POINT TO CYCLOGENESIS ALONG THE FRONT...WITH
THE NEW SFC LOW TRACKING ACROSS THE GREAT LAKES THU NIGHT. SHOULD
GET ANOTHER ROUND OF WIDESPREAD RAIN THU NIGHT.

WITH THE DEPARTURE OF THE STRONG RIDGE AND THE INTRODUCTION OF RAIN
CHANCES AND MORE CLOUDS...TEMPS ARE EXPECTED TO TAKE A TUMBLE.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 621 AM CDT SUN SEP 28 2014

MAIN CONCERN FOCUSES ON VALLEY FOG/STRATUS THIS MORNING AND
POSSIBLE REPEAT TONIGHT WITH LIGHT WINDS AND MOSTLY CLEAR SKIES.
STILL THINKING THERE WILL BE A WINDOW FROM 12-14Z FOR AREAS OF
DENSE RIVER VALLEY FOG TO SET UP WHICH WILL IMPACT KLSE. LOOK FOR
THIS FOG TO BURN OFF BY 15Z...SETTING UP VFR CONDITIONS FOR THE
REST OF TODAY INTO THE MAJORITY OF TONIGHT. MODELS SUGGESTING
ANOTHER NIGHT OF LIGHT WINDS AND MOSTLY CLEAR SKIES WHICH WILL
LEAD TO AREAS OF RIVER VALLEY FOG/STRATUS ONCE AGAIN. THIS
TIME...FOG NOT EXPECTED TO BE AS DENSE AS THERE WILL BE A
SOUTHWEST WIND AT BLUFFTOP FLOW AT 10-15KT...WHICH WOULD PRODUCE
MORE OF A IFR RIVER VALLEY STRATUS POTENTIAL INSTEAD. AT THIS
POINT...INTRODUCED A 5SM SCT003 MENTION AT KLSE IN THE MONDAY
09-12Z TIME FRAME.

&&

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

$$

SHORT TERM...RIECK
LONG TERM....RIECK
AVIATION...DAS



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