Area Forecast Discussion
Issued by NWS La Crosse, WI

Home | Current Version | Previous Version | Text Only | 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 281720
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1220 PM 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 SUN-FILLED 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 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1220 PM CDT SUN SEP 28 2014

GOOD VFR CONDITIONS THIS AFTERNOON/EVENING WITH LIGHT SOUTH TO
SOUTHWEST WINDS AND FEW TO SCT 4K-5K FT DIURNAL CUMULUS DURING THE
PEAK HEATING HOURS THIS AFTERNOON. LIGHT SFC-925MB WINDS AND CLEAR
SKIES TONIGHT AGAIN SET THE STAGE FOR RADIATIONAL VALLEY FOG.
HOWEVER...A COLD FRONT APPROACHING FROM THE NORTH SENDS THE BOUNDARY
LAYER WINDS AROUND TO THE WEST LATE TONIGHT. THESE WINDS AND FALLING
PRESSURES AHEAD OF THE FRONT NOT ALL THAT FAVORABLE FOR THE LATE
NIGHT/EARLY MORNING BR/FG. REMOVED THE BR MENTION FROM KRST BUT DID
LEAVE A 5SM BR AT KLSE IN THE 09Z-1430Z PERIOD WITH VARIABLE WINDS
IN THE MS VALLEY DURING THAT TIME. FRONT LOOKS TO SAG THRU THE TAF
SITES AROUND MID MORNING MON...WITH LIGHT NORTHWEST WINDS AND A BKN
4K-5K FT STRATO-CU DECK TO FOLLOW BEHIND IT.

&&

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

$$

SHORT TERM...RIECK
LONG TERM....RIECK
AVIATION.....RRS



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