FXUS63 KMKX 050935
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
335 AM CST SAT DEC 5 2009

.DISCUSSION...FORECAST FOCUS SQUARELY ON THE 2 SNOW EVENTS...SUNDAY 
NIGHT INTO MONDAY AND THEN LATER TUESDAY INTO WEDNESDAY.

TODAY- CONFIDENCE...LOW TO MEDIUM
WATER VAPOR/RUC COMBO SHOWS SHORTWAVE ACROSS IOWA...19 
UNITS...SHIFTING SOUTHEAST. WEAK SURFACE RIDGE INTO SOUTHERN WI
GIVING WAY TO DEVELOPING WARM AIR ADVECTION PATTERN. THIS TYPE OF
PATTERN HAS ME WORRIED FOR CLEARING OUT A CLOUD COVER...ALTHOUGH
HARD TO ARGUE WITH UPSTREAM TRENDS AT THE MOMENT. IN FACT LOW
LEVEL RH PROGS ARE HANDLING THE ONGOING CLOUD SHIELD PRETTY WELL
AND THE PROGS DO BRING THIS BACK EDGE THROUGH. INTERESTING POCKET
OF 700 MILLIBAR OMEGA THAT DEVELOPS LATER ON WITH SOME INCREASE IN
700 RH AS WELL.

TONIGHT- CONFIDENCE...LOW
ELONGATED SHEAR VORTICITY WITHIN BROAD WEAKLY CYCLONIC FLOW. POCKET 
OF 700 LIFT/MOIST SHIFTS EAST OF THE AREA. LOOKING AT 285K SEEING 
FOCUSED AREA OF ADIABATIC OMEGA WITH LOWER CONDENSATION PRESSURE 
DEFICITS ACROSS THE NORTHERN CWA. INGREDIENTS PLOTS ALSO HINTING AT 
SOME QPV WITH OVERLAP OF QVECTOR CONVERGENCE AND EPV. SURFACE 
TROUGH AXIS MOVES INTO THE CWA. MODEL QPF KEEPS EVERYTHING NORTH 
EXCEPT FOR THE WRF20 AND WILL STICK WITH THE DRY FORECAST. GUID POPS 
SHOWING SOME SLIGHT POTENTIAL IN THE NORTH AND WILL INTRODUCE A 
SLIGHT CHANCE OF SNOW SHOWERS IN THE NORTH FOR NOW.

SUNDAY- CONFIDENCE...LOW TO MEDIUM
UPPER RIDGE POPS UP ACROSS THE CWA IN ADVANCE OF THE NEXT SYSTEM. 
925 TEMPS MODIFY BUT MAY BE OFFSET BY MORE CLOUD COVER. TEMPS WILL 
BE TRICKY. GFS DEVELOPS A NARROW RIBBON OF LIGHT QPF NEAR THE WI/IL 
BORDER IN THE AFTERNOON IN RESPONSE TO LOWER CONDENSATION PRESSURE 
DEFICTS BUT OMEGA APPEARS WEAK. WITH THIS AND THE SURFACE TROUGH IN 
THE AREA WILL OPT TO ADD IN SOME FLURRIES AT THIS POINT. OVERALL THOUGH
WILL LEAN TOWARDS THE DRIER LOOK OF ECMWF/HPC/NAM/CANADIAN.

SUNDAY NIGHT AND MONDAY- CONFIDENCE...LOW
OPEN AND IMPRESSIVE NEGATIVE TILT SHORTWAVE APPROACHES THE AREA. 
JET DYNAMICS ARE FAVORABLE WITH 250 MILLIBAR LEFT EXIT REGION 
CREATING FAVORABLE UPPER DIVERGENCE ACROSS SOUTHERN WI. LOOKING AT 
1000-500 MILLIBAR THICKNESSES AND COBB PLUS SURFACE TEMPERATURES 
WILL GO WITH AROUND A 17:1 RATIO FOR THIS SYSTEM. AVERAGE QPF 
AMOUNTS ARE AROUND 0.20 INCH...SO A GOOD 2 TO 4 INCHES SEEMS 
REASONABLE. VERTICAL MOTION MAX WITHIN DENDRIDIC GROWTH ZONE ADDS 
CONCERN AND ALSO TIMING SUPPORTS A POTENTIAL IMPACT TO THE MONDAY 
MORNING RUSH...SO ADVISORY MAY BE NEEDED.

TUESDAY THROUGH WEDNESDAY- CONFIDENCE...LOW
GFS/ECMWF AND CANADIAN ARE IN DECENT AGREEMENT WITH EACH OTHER. 
INTERNAL CONSISTENCY IS THERE AS WELL. OVERALL FOLLOWING ECMWF PER 
HPC'S INPUT AND THIS FAR OUT...WOULD PREFER TO LEAN IN THAT 
DIRECTION. THE ECMWF TRACK OF THE SURFACE LOW IS A LITTLE FURTHER 
SOUTH THAN IDEAL AND 850 LOW IS SOUTH AND MORE BROAD HOWEVER THE 
POSITION OF THE 700 MILLIBAR LOW CENTER IS FAVORABLE. THIS FAR 
OUT...LOTS CAN STILL CHANGE. RAISED POPS TUESDAY NIGHT AND WEDNESDAY 
BUT NO REAL TINKERING WITH SNOW AMOUNTS FOR NOW. WITH TIGHT GRADIENT 
EVOLVING ACROSS THE CWA ON BACK SIDE OF LOW INTRODUCED BLOWING SNOW. 
HARD TO NOT SEE THIS ENDING UP AS A WATCH/WARNING EVENT.

&&

.AVIATION...PATCHY SC REDEVELOPMENT NOTED LAST SEVERAL HOURS OVER 
PARTS OF ERN IA WITH LINGERING LOW LEVEL MOISTURE AND MIXING.  STILL 
A FEW FLURRIES GETTING SHAKEN OUT AS WELL. STILL EXPECT GRADUAL 
CLEARING TODAY AS DRIER AIR WORKS IN FROM THE WEST.  ANY CLEARING WL 
BE SHORT LIVED HWVR AS VFR CLDS TO RETURN TNGT IN STRONG WARM AIR 
ADVECTION.  ENOUGH MID LEVEL MOISTURE RETURN AND FORCING TO CAUSE 
ISOLD TO SCT -SHSN BUT NOT ENUF CONFIDENCE AT THIS POINT TO PUT IN 
TAFS.  

&&

.MARINE...DESPITE STEEP LOW LEVEL LAPSE RATES TODAY...EXPECT WINDS 
TO REMAIN BELOW SMALL CRAFT ADVY LEVELS OVER NEARSHORE AS PRESSURE 
GRADIENT TIGHTENS A BIT AHEAD OF DEVELOPING PLAINS LOW PRESSURE 
TROUGH.  A FEW GUSTS MAY EXCEED 20KTS.  LAKE TEMP ESTIMATED TO BE 
AROUND 6C FROM GREAT LAKES COASTAL FORECAST SYSTEM. INCREASING LOW 
LEVEL WINDS TNGT TO 20 TO 30KTS JUST OFF SURFACE MAY BE ABLE TO MIX 
DOWN TO LAKE SURFACE DUE TO STEEP LAPSE RATE IN THE VERY LOW 
LEVELS.  WILL HOLD OFF ON SMALL CRAFT ADVY AT THIS POINT...BUT WL 
NEED TO WATCH CLOSELY TODAY.  SMALL CRAFT CONDITIONS WILL AGAIN BE 
APPROACHED ON BACKSIDE OF LOW PRESSURE ON MONDAY. 

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&

$$
SHORT/LONG TERM...PC
AVIATION/MARINE...MBK