Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 271935
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
235 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 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1215 PM CDT MON OCT 27 2014

CONTINUED WITH A VFR FORECAST THROUGH THE PERIOD. LOW CLOUDS/STRATUS
CONTINUE TO LOOK LIKE A NO-SHOW...EXCEPT FOR SOME SCT DIURNALLY
DRIVEN STRATO-CU IN THE 4K-5K FT RANGE LATER THIS AFTERNOON/EARLY
THIS EVENING. SFC-MID LEVEL LOW/TROUGH SLIDES ACROSS THE AREA
TONIGHT...WITH INCREASING NORTHWEST FLOW/DEEPER SUBSIDENCE SCOURING
OUT MUCH OF THE MOISTURE. GRADIENT TIGHTENS WITH STEEP LOW LEVEL
LAPSE RATES FOR MIXING...WITH WEST TO NORTHWEST WINDS INCREASING
INTO THE 10-15KT RANGE LATER TONIGHT...THEN IN THE 15-20KT G25KT
RANGE WITH STEEP LOW LEVEL LAPSE RATES FOR LATER TUE MORNING/
AFTERNOON. THE NORTHWEST FLOW EVENTUALLY WRAPS SOME OF THE MOISTURE
BEHIND THE DEPARTING SYSTEM SOUTH/SOUTHEAST ACROSS THE AREA FOR
LATER TUE MORNING/AFTERNOON. SOUNDINGS AND X-SECTIONS SHOWING THIS
TO BE IN THE 4K-5K FT RANGE WHEN IT REACHES THE TAF SITES.


&&

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

$$

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



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