Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 280400
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1100 PM CDT MON OCT 27 2014

.SHORT TERM...(TONIGHT THOUGH WEDNESDAY)
ISSUED AT 235 PM CDT MON OCT 27 2014

MODELS UNDER-FORECASTED THE AMOUNT OF WARM/MOIST AIR THAT WOULD WORK
INTO THE AREA YESTERDAY...AND AS A RESULT...THE LOW STRATUS AND
AREAS OF DRIZZLE NEVER MANIFESTED. THUS...MORE SUNSHINE TODAY THAN
ORIGINALLY EXPECTED...AND A MILD AND FAIRLY NICE START TO THE WORK
WEEK. HOWEVER...ITS THE LAST DAY OF ABOVE NORMAL TEMPERATURES
FOR AWHILE...SO HOPE YOU GET OUT AND ENJOY IT.

A FEW SHOWERS HAVE DEVELOPED ACROSS WESTERN/NORTHERN IA EARLY THIS
AFTERNOON. SOME 600-700 MB FRONTOGENETIC FORCING AND A BIT OF UPPER
LEVEL ENERGY HAVING A HAND IN THIS...AS IS AROUND 500 J/KG OF
ELEVATED INSTABILITY. SFC OBS INDICATE CIGS ARE ABOVE 12 KFT...BUT
DESPITE A DRY SUB CLOUD LAYER...SOME LIGHT RAIN/SPRINKLES WERE
REACHING THE GROUND. EVEN A FEW STROKES OF LIGHTNING. CURRENT
TRAJECTORIES WOULD BRING THIS ACTIVITY ACROSS WESTERN PORTIONS OF
THE FORECAST AREA...EXITING NORTH AROUND 00Z.

MEANWHILE...A SFC LOW WAS TRACKING ACROSS NORTHEAST IOWA...AND WILL
SHIFT OVER NORTHEAST WI LATER THIS EVENING. THE ACCOMPANYING COLD
FRONT LAYS FARTHER SOUTH OF THE LOW...AND ITS CONVECTIVE POTENTIAL
TONIGHT LOOKS TO BE SOUTH OF THE FORECAST AREA.

THE UPPER LEVEL LOW SLIDES EAST ACROSS NORTHERN PORTIONS OF THE
REGION TUE...EXITING INTO SOUTHEAST CANADA TUE NIGHT. THE SYSTEM/S
SFC LOW LIFTS NORTHEAST...WITH A TROUGH HANGING WEST OF THE LOW
CENTER...ACROSS FAR NORTHERN PORTIONS OF MN. THE QG CONVERGENCE
HOLDS WELL NORTH...AS DOES THE WEAK LOW LEVEL FRONTOGENETIC LIFT.
HOWEVER...THE AREAS IS UNDER 500 MB CYCLONIC FLOW...AND 1000-850 MB
LAPSE RATES ARE AROUND 8 C/KM TUE AFTERNOON. MOISTURE WRAPS AROUND
THE LOW...WITH THE GFS AND NAM SINKING 850 MB SATURATION SOUTH
ACROSS MOST OF MN/WI DURING THE AFTERNOON. WHILE THE MAIN CLOUD
SHIELD LIKELY HOLDS MORE TO THE NORTH...SATURATION AND LAPSE RATES
SHOULD RESULT IN CU FORMATION. WHETHER OR NOT THE CLOUDS ARE DEEP
ENOUGH TO SUPPORT SOME LIGHT RAIN/SPRINKLE PRODUCTION IS IN
QUESTION. BETTER CHANCES WILL LIE TO THE NORTH.

.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 235 PM CDT MON OCT 27 2014

MODELS IN GOOD AGREEMENT WITH NORTHWEST FLOW TAKING OVER FOR THE
LATER HALF OF THE WORK WEEK...CONTINUING TO PUSH COLDER/SEASONABLE
AIR INTO THE REGION. GFS/NAM/ECMWF ALL HINT AT A WEAK PERTURBATION
MOVING ALONG THE FLOW...DROPPING ACROSS THE UPPER MISSISSIPPI RIVER
VALLEY WED NIGHT/THU. SOME WEAK QG CONVERGENCE WITH THIS
FEATURE...ALONG WITH SOME HINTS OF LOW LEVEL WARMING IN THE 850-925
MB LAYER. ITS A WEAK SYSTEM...BUT WOULD SEEM TO HAVE ENOUGH LIFT TO
PRODUCE SOME PCPN IF SATURATION IS GOOD. BUFKIT SOUNDINGS AND RH
FIELDS SUGGEST THAT WILL BE THE PROBLEM...BRINGING THIS SHORTWAVE
THROUGH RELATIVELY DRY. THE BULK OF THE SATURATION IS CONFINED ABOVE
800-700 MB. THAT SAID...SOME MID LEVEL LIGHT SHOWER/SPRINKLE
PRODUCING CLOUDS CAN/T BE RULED OUT. GOING TO KEEP THIS PERIOD DRY
FOR NOW.

A SFC HIGH BUILDS IN FRIDAY...MEANDERING TO THE SOUTHEAST THROUGH
THE WEEKEND. AN UPPER LEVEL RIDGE AXIS SLIDES IN ON SUNDAY.
HOWEVER...SFC WINDS LIKELY WON/T BECOME SOUTHERLY TILL NEXT
WEEK...AT LEAST AT THE CURRENT PACE OF THE HIGH/RIDGE. THIS WILL
KEEP THE REGION UNDER COOL/BELOW NORMAL TEMPERATURES THROUGH THE
WEEKEND.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1100 PM CDT MON OCT 27 2014

THE SURFACE LOW CONTINUES TO MOVE SLOWLY AWAY FROM THE REGION THIS
EVENING. THIS HAS ALLOWED ALL THE RAIN TO CONTINUE MOVING SLOWLY
AWAY FROM THE AREA AS WELL WITH LITTLE TO NO THREAT FOR ANY RAIN
AT EITHER TAF SITE THE REST OF TONIGHT. CEILINGS WILL REMAIN VFR
WHILE SLOWLY CONTINUING TO RISE THROUGH THE NIGHT WITH THE
EASTWARD PROGRESSION OF THE LOW. AN AREA OF GOOD LOW LEVEL LAPSE
RATES BEHIND THE LOW IS ALLOWING A PERIOD OF GUSTY WEST TO
NORTHWEST WINDS TO OCCUR AND THESE SHOULD PERSIST FOR A COUPLE
MORE HOURS AT KRST BEFORE DIMINISHING. NOT SURE THE GUSTS WILL
MATERIALIZE AT KLSE DUE TO THE WESTERN BLUFFS BLOCKING THESE WINDS
FROM GETTING INTO THE VALLEY. THE 28.00Z NAM AND MOST OF THE MESO
MODELS CONTINUE THE TREND OF TAKING THE UPPER LEVEL LOW ACROSS
NORTHERN MINNESOTA AND WISCONSIN TUESDAY AND KEEPING THE SHOWERS
WELL TO THE NORTH...SO HAVE MAINTAINED DRY FORECASTS FOR BOTH TAF
SITES. GOOD LOW LEVEL LAPSE RATES WILL DEVELOP BY MID MORNING AND
WITH PLENTY OF WIND IN THE MIXED LAYER...LOOK FOR A GUSTY WEST
WIND FOR A GOOD SHARE OF THE DAY. THE NAM SUGGESTS THESE GOOD
LAPSE RATES WILL REMAIN IN PLACE INTO THE EVENING TO KEEP THE
GUSTS GOING BUT WITH A BIT OF A DECREASE IN THE SPEEDS.

&&

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

$$

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



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