FXUS63 KMKX 060933
AFDMKX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
333 AM CST SUN DEC 6 2009
.DISCUSSION...FORECAST FOCUS REMAINS ON THE 2 SNOW EVENTS...TONIGHT
INTO MONDAY AND THEN THE POTENTIAL BIGGIE TUESDAY INTO WEDNESDAY.
TODAY- CONFIDENCE...MEDIUM
UPPER RIDGE POPS UP ACROSS THE CWA IN ADVANCE OF THE NEXT SYSTEM.
WEAK NE/SW ORINTED TROUGH DRIFTING THROUGH CWA. WEAK
FRONTOGENETICAL/ISENTROPIC ASCENT CONTINUES TO SHOW UP IN THE FAR
SOUTHERN CWA THIS AFTERNOON TCONSENSUS OF MODELS KEEPS MEASURABLE
SOUTHWEST OF CWA. WILL TREND TOWARDS SLIGHTLY COOLER 3 HOURLY MOS
TEMPS.
TONIGHT AND MONDAY- CONFIDENCE...LOW TO MEDIUM
OPEN WAVE APPROACHES WITH INCREASING UPPER DIVERGENCE ASSOCIATED
WITH LEFT FRONT EXIT REGION OF JET TO THE SOUTH. THIS DIVERGENCE
MAXES OUT AROUND 6Z. ISENTROPIC LIFT IS QUITE WEAK AND ACTUALLY
SHOWS SOME HIGHER CONDENSATION PRESSURE DEFICITS IN THE SOUTHEAST
WITH BETTER SATURATION NORTH. THE GFS FITS THIS PATTERN IN THE QPF
WITH VALUES RANGING FROM NEAR 0.25 INCH IN SHEBOYGAN TO NOTHING IN
KENOSHA. THE NAM IS A MORE UNIFORM 0.15 INCH FOR MUCH OF THE CWA.
LOOKING AT THE 1000-500 MILLIBAR THICKNESSES AND COBB PLUS SURFACE
TEMPERATURES WILL STICK WITH THE 17:1 RATIO FOR THIS SYSTEM. SO
THE 2 TO 4 INCH IDEA IS STILL HARD TO ARGUE WITH...WITH SOME LOWER
AMOUNTS POSSIBLE IN THE FAR SOUTHEAST. INTERESTINGLY THE MAV MOS
HAS NO LIKELY POPS ANYWHERE IN THE CWA FOR THIS EVENT. THE STRICT
SNOWFALL CRITERIA FOR ADVISORY NOT BEING MET WITH THE 2 TO 4
IDEA...HOWEVER AN ADVISORY MAY EVENTUALLY BE NEEDED FOR THE
MONDAY MORNING COMMUTE TIMEFRAME.
TUESDAY THROUGH WEDNESDAY- CONFIDENCE...LOW
WELL THE 00Z ECMWF HAS THROWN A TEMPORARY CURVEBALL WITH A MUCH
WARMER/NORTHWEST TRACK OF THE SURFACE LOW. 543DM THICKNESSES ARE
WRAPPED NORTHWEST BACK INTO THE CWA WITH THE 850 MILLIBAR ZERO
LINE INTO THE SOUTHEAST CORNER. HOWEVER NOT READY TO JUMP ON ONE
RUN TO INTRODUCE A MIX AS THE CANADIAN STILL SHOWING ALL SNOW AND
THE GFS HAS ALSO BEEN VERY CONSISTENT WITH A FAVORABLE LOW TRACK
FOR ALL SNOW. ALSO ECMWF 700 MILLIBAR LOW AND SOUTHWARD
POSITIONING OF MAIN DYNAMICS SUGGEST A MORE SOUTHERN SURFACE LOW
STILL POSSIBLE FROM THE ECMWF IN FUTURE RUNS. THIS FAR OUT WOULD
STILL EXPECT AT LEAST SOME VARIABILITY. HOWEVER HPC BLENDED
FIELDS GOING WITH A 50/50 OF GFS/ECMWF WHICH WOULD GIVE GREATER
CONFIDENCE TO THE ALL SNOW IDEA. GFS/HPC SHOWING 0.80 LIQUID WHILE
THE ECMWF INDICATING ABOUT 1.10 INCH OF LIQUID. THIS SYSTEM WILL
HAVE NO SHORTAGE OF MOISTURE AS IT LIFTS NORTHEAST TOWARDS US.
BLOWING/DRIFTING COULD BECOME A SUBSTANTIAL PROBLEM WITH
IMPRESSIVELY TIGHT GRADIENT ON BACK SIDE OF LOW IN THE COLD
ADVECTION REGIME. DISCUSSED THE WATCH SITUATION WITH SURROUNDING
OFFICES BUT CONSENSUS IS TO HOLD OFF...AT LEAST FOR NOW...BUT
LIKELY TO COME IN THE NOT TOO DISTANT FUTURE.
THURSDAY- CONFIDENCE...LOW
STRONG LOW LIFTS NORTHEAST AWAY FROM THE AREA BUT GRADIENT STILL
FAIRLY TIGHT. LIGHT QPF GENERATED BY GFS WITH ECMWF MORE THE DRY
LOOK. ECMWF SHOWING 925 TEMPS -16 TO -19C WITH 850 TEMPS AROUND
-22C. HIGHS COULD STRUGGLE TO MAKE THE TEENS AND POSSIBLY SOME BELOW
ZERO TEMPS THURSDAY NIGHT WITH FRESH SNOWCOVER. WIND CHILL ISSUES
NOT OUT OF THE QUESTION EITHER.
&&
.AVIATION...CURRENT OVC VFR CIGS TO YIELD TO SCT-BKN THIS MRNG. CAN
NOT COMPLETELY RULE OUT LINGERING VFR CLOUDS WITH WK LOW LEVEL
CONVERGENCE ALONG SFC TROUGH AND LINGERING MOISTURE. EXPC MVFR AND
POSSIBLY IFR CIGS/VSBYS SPREADING IN LATER TNGT ASSOCIATED WITH SNOW
EVENT. AXIS OF HEAVIEST SNOW EXPCD NORTH OF KENW AT THIS TIME.
&&
.MARINE...WEAK SURFACE TROF OVER CENTRAL WI WL MOV SLOWLY SWD ACROSS
NEARSHORE TODAY RESULTING IN DIMINISHING SW WNDS TURNING TO THE
NNE. WNDS WL LKLY DMSH TO LGT/VRBL IN SOUTH TNGT. WITH LOW PRES
MOVG ALG SFC TROF LATER TNGT INTO MON...WNDS TO RMN VRBL
TNGT...TURNING TO THE N TO NW ONCE SFC LOW PASSES TO THE EAST MON
AFTN. GALE FORCE WNDS POSSIBLE WED INTO THU WITH DEEP LOW PRES.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
SHORT/LONG TERM...PC
AVIATION/MARINE...MBK
