168 FXUS63 KMKX 250542 AAB AFDMKX AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI 1142 PM CST THU JAN 24 2013 .UPDATE...NO CHANGE FROM PREVIOUS ISSUANCE AREA 00Z RAOBS SHOWING THE VERY DRY LAYER...DEW POINT DEPRESSIONS ON THE ORDER OF 30C IN THE 850-800MB LAYER...THAT HAVE BEEN PREVENTING MUCH IN THE WAY OF GROUND TRUTH BELOW THE 15 TO 20 DBZ RETURNS WITH THE INITIAL WAA ALL THE WAY BACK TO CENTRAL MN. SNOW REPORTS HAVE BEEN LIMITED TO NRN MN AND NW WI. LATEST 01Z RAP AND NEW 00Z NAM SHOW THE DRY LAYER AROUND 850 MB WILL BE TOUGH TO SATURATE OVER THE CWA UNTIL AFTER 09Z...WITH REDUCED QPF AMOUNTS. 23Z HRRR DOES NOT BRING ANY QPF INTO THE CWA FOR THIS EVENT. RAP AND NAM SOUNDINGS DO EVENTUALLY SATURATE. REDUCED QPF AND THUS SNOW AMOUNTS ACROSS THE CWA...BUT STILL WORRIED ABOUT HIGH SNOW TO LIQUID RATIOS WITH THE DEPTH OF OF THE SATURATED DENDRITIC GROWTH ZONE...WITH SPC PROBABILITY OF 200 MB OR MORE AROUND 90 PCT ACROSS THE FAR NORTH AND 50 PCT DOWN TO THE IL BORDER IN THE ERN CWA. THE DEEP DGZ IS BEING SHOWN ON RAP SOUNDINGS IN THE EAST WITH DECENT OMEGA...SO ONLY REDUCED THE AMOUNTS BY 1/2 INCH TO 1 INCH FOR NOW. AVIATION/06Z TAFS/... WITH DELAY IN ONSET OF SNOW PLAN ON KEEPING VFR CONDITIONS AT TAF SITES UNTIL 09Z AT KMSN AND 10Z-11Z EAST...THEN MVFR WITH EXPECTED START OF STEADY LIGHT SNOW. WILL KEEP THE PERIOD OF IFR VSBYS AT ERN SITES BETWEEN 15Z AND 18-19Z AS DEEP SNOW GROWTH ZONE COINCIDENT WITH LIFT BRINGS POTENTIAL OF HIGH SNOW TO LIQUID RATIOS. SNOW BEGINS TO TAPER OFF FROM WEST TO EAST AFTER 18Z...THOUGH MVFR CIGS AND VERY LIGHT SNOW OR FLURRIES WILL CONTINUE UNTIL THE COLD FRONT CLEARS THE CWA AROUND 00Z. SOUNDINGS ALSO SUPPORT WIND GUSTS OF 20 TO 25 KTS AT ERN SITES AND AROUND 20 KTS AT KMSN BY MID TO LATE MORNING...THEN DIMINISHING BEHIND THE FRONT EARLY IN THE EVENING. MARINE... KEPT START TIME TO SMALL CRAFT ADVISORY ...THOUGH A FEW GUSTS HAVE REACHED 24-25 KNOTS AT KENOSHA AND POINTS SOUTH...DO NOT EXPECT FREQUENT CRITERIA LEVEL GUSTS TO KICK IN UNTIL 09Z AND WILL BE MAINLY NORTH OF MILWAUKEE. NEXT SHIFT WILL HAVE TO MONITOR FOR EITHER TO EXTEND THE AREA TO BE COVERED BY THE ADVISORY...OR START EARLIER IF WINDS CLIMB. PREV DISCUSSION... /ISSUED 410 PM CST THU JAN 24 2013/ SHORT TERM... TONIGHT AND FRIDAY...FORECAST CONFIDENCE...MEDIUM TO HIGH WILL SEE SOME LAKE EFFECT JUST BRUSH THE LAKE SHORE INTO THE EVENING. NOT REALLY EXPECTING MUCH MORE THAN FLURRIES. BIGGER ISSUE WILL BE WIDESPREAD SNOWFALL TONIGHT INTO FRIDAY. HIGH CONFIDENCE IN ACCUMULATING SNOW ACROSS THE FORECAST AREA. MAIN PROBLEMS ARE TIMING OF THE SNOW AND AMOUNTS. THE NAM AND GFS CONTINUE TO CHEW ON A LOT OF DRY AIR THIS EVENING INTO EARLY TONIGHT...WHILE THE ECMWF AND CANADIAN SATURATE A LOT FASTER. LEANED TOWARD THE SLOWER SOLUTIONS BASED ON SHORT TERM MESO MODELS LOOKING SIMILAR TO THE NAM. LIQUID TO SNOW RATIOS ARE THE OTHER ISSUE. SOUNDINGS ARE SHOWING A VERY DEEP DENDRITE GROWTH LAYER...AS DEEP AS 350 MB IN THE NORTH. WITH 1000-500 MB THICKNESS VALUES IN THE 520S AND AND TEMPERATURES IN THE TEENS...EXPECTING VERY HIGH SNOW RATIOS. TOOK THEM AS HIGH 25 TO 1 IN THE NORTH...BUT WOULD NOT BE SURPRISED IF THEY GET EVEN HIGHER. ENDED UP WITH SIMILAR STORM TOTAL SNOW AMOUNTS AS PREVIOUS FORECAST...RANGING FROM 1 TO 2 INCHES IN THE SOUTHWEST FORECAST AREA TO 3 TO 4 IN THE NORTHEAST. THOUGHT ABOUT A WINTER WEATHER ADVISORY IN THE NORTHEAST...BUT WINDS STAY UNDER CONTROL WHILE THE SNOW IS FALLING...AND AMOUNTS ARE GENERALLY BORDERLINE FOR AN ADVISORY. MAY CAUSE A FEW ISSUES FOR THE MORNING COMMUTE...ESPECIALLY IN THE EAST WHERE THE SNOW WILL HANG ON LATER INTO THE MORNING. WIDESPREAD SNOW WILL WIND DOWN TOMORROW MORNING...WITH SNOW SHOWERS POSSIBLY LINGERING INTO THE AFTERNOON...ESPECIALLY IN THE NORTHEAST. LOOKS LIKE HIGHS ACTUALLY BACK NEAR NORMAL TOMORROW. FRIDAY NIGHT THROUGH MONDAY...FORECAST CONFIDENCE MEDIUM BRISK NWLY WINDS AND COLD ADVECTION IN THE WAKE OF LOW PRESSURE MOVING EAST ACROSS THE GREAT LAKES WILL RETURN AN ARCTIC AIRMASS TO THE REGION FOR FRI NT. STEEP LOW LEVEL LAPSE RATES IN THE EARLY EVENING COULD MAINTAIN FLURRIES OR LIGHT SNOW SHOWERS IN ERN WI BEFORE CLEARING ARRIVES LATER IN THE EVENING. A 1030 MB POLAR HIGH WILL PROGRESS EWD ACROSS SRN WI SAT INTO EARLY SAT EVENING WITH LARGE SCALE RIDGING OVER THE PLAINS IN RESP0NSE TO AN UPSTREAM UPPER TROUGH IN THE PACIFIC NW AND A SHORTWAVE TROUGH MOVING INTO THE DESERT SW. THE SHORTWAVE TROUGH OVER THE DESERT SW WILL THEN LIFT NEWD AND EITHER TRACK INTO SRN WI OR REMAIN JUST TO THE SOUTH. THE ASSOCIATED PRESSURE TROUGH/WARM FRONT WILL PRODUCE A GOOD BAND OF PCPN BUT MODELS DIFFER ON PLACEMENT OF IT...SOME KEEPING THE MAIN AREA TO THE SOUTH. KEPT POPS IN THE 40-60 PERCENT RANGE FOR NOW. EITHER WAY...PCPN TYPE LOOKS MIXY. THERE COULD BE A BRIEF PERIOD OF TOTAL COLUMN SATURATION LEADING TO SNOW BUT DRIER AIR ALOFT AND A WARM LAYER COULD THEN RESULT IN FREEZING RAIN...FREEZING DRIZZLE...AND SLEET. PUT IN LIGHT ICE AND SNOW ACCUMULATION INTO SUNDAY FCST. THIS WOULD CONTINUE SUN NT AND POSSIBLY LINGER INTO MONDAY ALTHOUGH TEMPS MAY WARM ABOVE FREEZING...MEANING RAIN FOR PCPN TYPE. TEMPS EXPECTED TO GRADUALLY WARM THROUGH THIS PERIOD WITH HIGHS ABOVE FREEZING FOR MONDAY. LONG TERM... TUESDAY THROUGH THURSDAY...FORECAST CONFIDENCE LOW TO MEDIUM MODELS DIFFER ON STRENGTH AND PLACEMENT OF CYCLOGENESIS FROM THE PLAINS NEWD INTO ONTARIO CANADA FOR MON NT THROUGH WED...THUS THE LOWER CONFIDENCE. GIVEN THE TRACK IS TO THE WEST AND NORTH STILL WENT MILD WITH CHANCES OF RAIN THROUGH TUE. A STRONG COLD FRONT WILL THEN SWEEP THROUGH THE STATE TUE NT WITH RAIN CHANGING TO SNOW. BRISK NWLY WINDS AND COLD ADVECTION WILL PREVAIL INTO WED WITH A POLAR AIRMASS RETURNING. HIGH PRESSURE TO THEN SETTLE OVER THE REGION ON THU WITH BELOW NORMAL TEMPS EXPECTED. AVIATION/00Z TAFS/... MID AND HIGH LEVEL CLOUDS WILL KEEP SKIES MAINLY OVERCAST THROUGH THE REMAINDER OF THE DAY. WILL CONTINUE TO SEE CIGS NEAR MVFR LATE THIS AFTERNOON IN THE SOUTHEAST AS LAKE EFFECT SNOW SHOWERS BRUSH THE LAKE SHORE. STILL NOT EXPECTING MUCH IN THE WAY OF ACCUMULATION...IF ANYTHING AT ALL. OTHERWISE...DRY WEATHER AND VFR CONDITIONS WILL PREVAIL THROUGH THE EVENING HOURS. WILL SEE DETERIORATING CONDITIONS AFTER MIDNIGHT...AS WIDESPREAD SNOWFALL MOVES INTO THE AREA. MVFR CONDITIONS ARE LIKELY...WITH POSSIBLY LOWER VSBYS IN ANY AREAS OF MODERATE SNOWFALL. THE WIDESPREAD SNOWFALL WILL WIND DOWN FRIDAY MORNING...THOUGH COULD SEE A FEW SNOW SHOWERS LINGER INTO THE AFTERNOON. WILL LIKELY SEE MVFR CIGS LINGER THOUGH MUCH OF THE DAY TOMORROW. MARINE... WILL LET CURRENT SMALL CRAFT ADVISORY EXPIRE AT SCHEDULED 22Z TIME. LATEST WEBCAMS AND WAVE MODEL SHOW WAVES GENERALLY BELOW 4 FEET NOW. SOUTH WINDS WILL PICK UP TONIGHT...WITH WAVES LIKELY EXCEEDING 4 FEET NORTH OF PORT WASHINGTON. WILL THUS ISSUE ANOTHER SMALL CRAFT ADVISORY FOR LATE TONIGHT INTO FRIDAY AFTERNOON FOR THE NORTHERN MARINE ZONE. WINDS WILL BE CLOSE TO SMALL CRAFT ADVISORY ACROSS THE NEARSHORE WATERS LATER FRIDAY INTO FRIDAY NIGHT. SEEMS TOO BORDERLINE FOR AN ADVISORY AT THIS TIME THOUGH. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...SMALL CRAFT ADVISORY FROM 3 AM TO 4 PM CST FRIDAY FOR LMZ643. && $$ UPDATE...REM TONIGHT/FRIDAY AND AVIATION/MARINE...DDV FRIDAY NIGHT THROUGH THURSDAY...GEHRING