Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 272305
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
605 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 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 605 PM CDT MON OCT 27 2014

AN AREA OF LOW PRESSURE WAS MOVING ACROSS SOUTHWEST WISCONSIN LATE
THIS AFTERNOON. A FEW RADAR ECHOES SHOWING UP IN ASSOCIATION WITH
THIS LOW...BUT VERY LITTLE ACTUALLY BEING REPORTED AT THE SURFACE.
NOT EXPECTING THESE SHOWERS TO UPSCALE MUCH THIS EVENING SO WILL
KEEP BOTH TAF SITES DRY. LOOKING AT THE 27.18Z NAM AND 27.20Z
RAP...KLSE SHOULD HAVE AN ON AND OFF VFR CEILING AROUND 4000 FEET
INTO ABOUT THE MIDDLE OF THE EVENING BEFORE THIS LOWER LEVEL
MOISTURE GETS CLEANED OUT ON THE BACK SIDE OF THE SURFACE LOW. NOT
EXPECTING THIS LOWER MOISTURE TO GET INTO KRST SO A HIGH VFR
CEILING SHOULD PREVAIL THERE. HOWEVER...KRST COULD SEE SOME GUSTY
NORTHWEST WINDS THIS EVENING AS DECENT LOW LEVEL LAPSE RATES
DEVELOP BEHIND THE SURFACE LOW. VFR CEILINGS AND GUSTY WEST WINDS
SHOULD DEVELOP AT BOTH SITES TUESDAY MORNING. A STRONG SHORT WAVE
TROUGH WILL ROTATE AROUND THE UPPER LEVEL LOW THAT WILL BE MOVING
ACROSS NORTHERN MINNESOTA AND WISCONSIN. THIS WILL PROVIDE ENOUGH
FORCING TO GENERATE THE CEILINGS. AT THIS TIME...THE SHOWERS THAT
DEVELOP ON THE SOUTH SIDE OF THE UPPER LEVEL LOW ARE EXPECTED TO
REMAIN TO THE NORTH AND NOT IMPACT EITHER TAF SITE. GOOD LOW
LEVEL LAPSE RATES DEVELOP WITHIN THE MIXED LAYER TUESDAY THAT WILL
PRODUCE SOME GUSTY WEST WINDS.

&&

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

$$

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



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