FXUS63 KMKX 040929
AFDMKX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
329 AM CST FRI DEC 4 2009
.DISCUSSION...THE MAIN FORECAST CONCERNS AT THE MOMENT ARE SHAPING
UP TO BE SUNDAY NIGHT INTO MONDAY AND TUESDAY THROUGH AT LEAST TUESDAY
NIGHT.
TODAY- CONFIDENCE...MEDIUM
32 UNIT VORT MAX THAT DEPOSITED THE FOCUSED SNOW BAND ACROSS
SOUTHERN WI SHIFTING TO THE EAST THIS MORNING. HOWEVER UPPER FLOW
ALMOST STRAIGHT FROM THE NORTH WITH ANOTHER VORT...18 UNITS DIVING
SOUTH TOWARDS MN. IN BETWEEN THERE IS A WEAK 700/800 WAVE GENERATING
A CONTINUATION OF LIGHT SNOW SHOWERS/FLURRIES EXTENDING NORTHWEST TO
MSP PER 88-D MOSAIC. MAY MENTION EARLY SNOW SHOWERS OTHERWISE
FLURRIES. WITH 850 COLD POOL AND CLOUD COVER...EXPECT TEMPS TO BE AT
LEAST CLOSER TO COOLER NAM MOS VALUES.
TONIGHT- CONFIDENCE...LOW TO MEDIUM
UPPER LOW PROGGD TO CARVE OUT TROUGH ACROSS WI WITH THE LOW BECOMING
CENTERED NEAR WESTERN LAKE SUPERIOR. WEAK DIFFERENTIAL CYCLONIC
VORTICITY ADVECTION INTO THE AREA...THOUGH MAIN VORT ACTION LOOKS TO
BE CLOSER TO UPPER LOW CENTER WITH A WEAKER VORT SWEEPING THROUGH
EASTERN IOWA INTO NORTHERN ILLINOIS. NONE OF THE MODELS ARE
PICKING UP ON ANY QPF. WILL CERTAINLY HAVE SOME FLURRIES
MENTIONED...BUT LEAVE OUT MENTION OF ANY SNOW SHOWERS.
SATURDAY- CONFIDENCE...MEDIUM
NAM AND GFS BOTH SHOW 850 WARM AIR ADVECTION WITH WEAK TROUGH
DEVELOPING IN THE PLAINS. 280K ISENTROPIC PLOT SHOWS A SLUG OF
ADIABATIC OMEGA WITH SOME REASONABLY LOWER CONDENSATION PRESSURE
DEFICITS...THOUGH OVERALL LOOK TO SOUNDING IS A DRY ONE. WILL LEAVE
DRY FORECAST INTACT WITH SINGLE DIGIT MOS POPS AND SURROUNDING
OFFICES WITH THE DRY LOOK AS WELL.
SUNDAY- CONFIDENCE...MEDIUM
GFS AND ECMWF ON THE SAME PAGE WITH RESPECT TO FASTER FRONTAL SPEED.
850 FRONT LAGGING A BIT...BUT ECMWF AND GFS BOTH IMPLY A WEAK
SURFACE FROPA. UPPER LEVEL RIDGING NOTED AHEAD OF THE NEXT STORM
SYSTEM.
SUNDAY NIGHT AND MONDAY- CONFIDENCE...LOW
DECENT UPPER SHORTWAVE APPROACHES WITH NICE NEGATIVE TILT THOUGH NO
REAL CLOSED CIRCULATION ABOVE 850 MILLIBARS...AND THE OVERALL
SURFACE CIRCULATION FAIRLY WEAK. NAM IS THE MOST AGGRESSIVE WITH
ROBUST QPF NUMBERS. WILL STEER LOWER THAN THE NAM THIS FAR OUT AND
SIDE WITH A GFS/SREF/ECMWF/HPC BLEND. WILL GO WITH A FIRST GUESS OF
1-3 INCHES.
TUESDAY AND TUESDAY NIGHT- CONFIDENCE...LOW
BY FAR THE BIGGEST STORM POTENTIAL. ONE TO WATCH AS MODELS HAVE BEEN
FAIRLY CONSISTENT BRINGING A STORM INTO THE MIDWEST. LOTS OF DETAILS
YET TO GET IRONED OUT WITH RESPECT TO THE STORM TRACK AND PRECIP
TYPES. GETTING SOME IMPRESSIVE SIGNALS FROM THE INGREDIENTS PLOTS
AND ALSO GETTING DECENT VV IN THE SNOW GROWTH REGION. THIS MAY END
UP NEEDING A WATCH/WARNING IN ALL OR PART OF THE CWA AS TIME DRAWS
CLOSER. FIRST VERY PRELIMINARY SWING AT AMOUNTS IS 4-8 INCHES...BUT
AGAIN...LOTS TO SORT OUT AND TRACK RIGHT NOW IS TENDING TO FAVOR THE
NORTH AND NW PART OF THE CWA WITH SOME WARM AIR WRAP-IN OFF THE LAKE
POTENTIALLY CUTTING DOWN AMOUNTS THERE. STAY TUNED ON THIS ONE.
&&
.AVIATION...SOME CLEARING HAS OCCURRED EARLY THIS MORNING ACROSS THE
SOUTHEAST BUT THIS IS DUE TO THE SUBSIDENCE/DRYING ASSOCIATED WITH
THE DEPARTING MID LEVEL SHORT WAVE. LARGE SHIELD OF CLOUDS ROTATING
IN AND STRADDLING THE MVFR/VFR THRESHOLD OF 3KFT SHOULD OVERSPREAD
THE ENTIRE AREA THIS MORNING. COLD AIR ALOFT WILL GENERATE STEEP LOW
LEVEL LAPSE RATES TODAY AND INTO THE EVENING...AND THIS SHOULD ALSO
LEAD TO FLURRIES ON AND OFF FOR MUCH OF THE DAY. WEAK RIDGING PUSHES
IN TONIGHT INTO SATURDAY AND WOULD EXPECT THE STRATUS TO EVENTUALLY
SCOUR...BUT THIS IS AT THE END OF THE TAF PERIOD.
&&
.MARINE...CONDITIONS WILL BE APPROACHING SMALL CRAFT ADVISORY LEVELS
TODAY INTO TONIGHT AS THE PRESSURE GRADIENT TIGHTS ACROSS THE AREA.
HOWEVER...IT APPEARS WINDS WILL STAY JUST BELOW THRESHOLD AND DUE TO
THE OFF SHORE NATURE OF THE WIND...WAVES WILL LIKELY STAY BELOW
CRITERIA AS WELL. ANY SMALL BOATS OUT THERE SHOULD STILL EXERCISE
CAUTION.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
SHORT/LONG TERM...COLLAR
AVIATION/MARINE...DAVIS
