FXUS63 KGRB 261715
AFDGRB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1115 AM CST SAT DEC 26 2009
.UPDATE...THIS AFTERNOON INTO SUNDAY
STORM THAT AFFECT CHRISTMAS TRAVEL JUST WILL NOT GO AWAY. SEVERAL
FACTORS TO DEAL WITH ON THE MORNING/EARLY AFTERNOON UPDATE. SOME
GUIDANCE NOW SUGGESTING THAT ADVISORIES MAY BE NEED TO BE PUSHED
FURTHER WEST AND NORTH OF CURRENT ADVISORIES. ALONG THE LAKESHORE...
FAIRLY DECENT LAKE EFFECT SNOW SHOWERS AFFECTING MANITOWOC INTO
SOUTHERN DOOR COUNTY. DOPPLER RADAR INDICATED AROUND AN INCH PER
HOUR SNOWFALL RATES. AT THIS POINT...THE HEAVIER SNOW SHOWERS
ARE MOVING TO THE NORTH NORTHWEST AT A PRETTY GOOD CLIP.
SLOW MOVING LOW PRESSURE ACROSS SOUTHEAST IOWA IS EXPECTED TO
MOVE NORTHEAST INTO SOUTHEAST WISCONSIN TONIGHT. THE SYSTEM WILL
SPREAD THE SYNOPTIC SNOW WITH THIS SYSTEM ACROSS MUCH OF CENTRAL
AND NORTHEAST WISCONSIN LATER THIS AFTERNOON. LATEST OBSERVATION
OUT OF ROCKFORD INDICATED 4 INCHES OF NEW SNOW THIS MORNING WITH
SYSTEM.
BASED ON RADAR AND SURFACE OBSERVATIONS...WILL NEED TO EXPAND
ADVISORIES NORTH AND WEST. THE QUESTION IS HOW FAR NORTH AND WEST
SINCE THERE ARE DIFFERENCES BETWEEN THE GFS AND WRF. WILL ALSO
NEED TO CONTEMPLATE UPGRADING TO A WARNING ALONG THE LAKESHORE FOR
A COMBO OF LAKE ENHANCEMENT AND SYNOPTIC SNOWS. WILL HOPEFULLY HAVE
NEW ZONES/GRIDS AND ADVISORIES OUT SOMETIME AFTER THE NOON HOUR.
WILL NOT WAIT UNTIL THE 4 PM PACKAGE.
&&
.PREV DISCUSSION...ISSUED AT 608 AM CST SAT DEC 26 2009...
UPDATE...IMPRESSIVE RADAR RETURNS WITH LAKE EFFECT SNOW SHOWERS.
NEAR 50 DBZ NOTED AT 12Z E OF KSUE. IN ADDITION...AREA OF 35 DBZ
ALONG SHORELINE FROM SW OF KEWAUNEE TO PT BEACH STATE FOREST LIKELY
PRODUCING A QUICK INCH OR SO.
AREA OF SNOW ASSOC WITH IA SFC LOW WILL MOVE INTO FCST AREA THIS
AFTN. THUS...ADVISORY ISSUED FOR THE LAKE SHORE COUNTIES...AREA
MOST LIKELY TO SEE 3+ INCHES BETWEEN NOW AND MIDN.
JKL
DISCUSSION ISSUED AT 322 AM CST SAT DEC 26 2009...
SHORT TERM...TODAY THROUGH SATURDAY.
MESOANALYSIS SHOWS SFC LOW JUST S OF KDSM AT 08Z THIS AM...AFTER
MAKING A LOOP AROUND THE STATE OF IA. COLD OCCLUSION FINALLY PUSHED
THRU THE FAR N PART OF FCST AREA AND TEMPS FALLING THERE.
26/00Z AND 26/06Z MODELS SHOW SFC LOW MOVING ACROSS EASTERN WI
NEAR KMTW AND KSBM BY SAT NIGHT. AREA OF STEADIER SNOW WILL MOVE
BACK INTO SE PART OF FCST AREA BY AFTN. BEFORE THAT...HOWEVER...
SCT SNOW SHOWERS MOVING OFF LAKE MICHIGAN AND WILL AFFECT THE FAR
ERN PART OF FCST AREA. MODEL SOUNDINGS INDICATE SOME LAKE-INDUCED
CAPE WITH MODERATELY FAVORABLE AIR/LAKE DELTA T AND WINDS.
SYNOPTIC LIFT ASSOC WITH UPPER SYSTEM ALSO FAVORABLE. THINKING 1-2
INCHES ACROSS FOX VALLEY N THROUGH HWY 141 CORRIDOR. A COUPLE OF
INCHES MORE POSSIBLE IN LAKESHORE COUNTIES. WILL HOLD OFF ON
ADVISORY FOR NOW...BUT LAKESHORE COUNTIES WILL HAVE TO BE
MONITORED AS ACCUMS COULD APPROACH 3-4 INCHES IN SPOTS.
HIGH TEMP FCST TODAY TWEAKED A BIT GIVEN CURRENT CONDITIONS...BUT
NO SIGNIFICANT CHANGES MADE. MINS TNGT AND MAX SUNDAY CHANGED
LITTLE FROM PREV FCST.
LONG TERM...SUNDAY NIGHT THROUGH FRIDAY.
TWO MAIN CONCERNS DURING THIS PART OF THE FORECAST ARE THE
DEPARTURE OF THE CURRENT SYSTEM AND ARRIVAL OF A CLIPPER SYSTEM
LATER IN THE WEEK.
MEDIUM RANGE MODELS HAD A CLOSED 500MB LOW CENTERED AROUND
SOUTHERN LOWER MICHIGAN AND A SURFACE TROUGH FROM NORTHERN QUEBEC
TO NORTHERN LAKE MICHIGAN AT 00Z MONDAY. NORTHERLY FLOW OF COLD
AIR ON THE BACK SIDE OF THESE DEPARTING FEATURES SHOULD RESULT IN
ENOUGH INSTABILITY AND FAVORABLE WIND DIRECTION FOR SOME LAKE
EFFECT SNOW SHOWERS IN THE SNOWBELT REGION...ALONG WITH A CHANCE
OF FLURRIES FOR THE REST OF THE AREA. SOME CLEARING IS LIKELY FOR
MONDAY NIGHT AS A SURFACE HIGH AND AN UPPER RIDGE SLOWLY MAKE
THEIR WAY TOWARD THE REGION. TIMING OF THE CLIPPER SYSTEM THAT
WILL BRING THE NEXT CHANCE OF SNOW TO THE AREA IS STILL A BIT
UNCERTAIN RIGHT NOW...BUT GRIDS HAVE SLIGHT CHANCE POPS GOING FOR
WEDNESDAY AND CHANCE POPS IN THE EAST ON WEDNESDAY NIGHT. NOT THE
GREATEST OF CONFIDENCE IN THIS TIMING BUT LATER SHIFTS CAN ADJUST
THINGS BASED ON NEWER MODEL DATA.
DID NOT REALLY MAKE MAJOR CHANGES TO MAX AND MIN TEMPERATURES
DURING THE EARLY HALF OF THE WEEK. EXPECT COLDER LOWS AS WINDS
DECREASE AND SKIES START TO CLEAR ONCE THE CURRENT SYSTEM STARTS
MOVING AWAY FROM THE STATE.
AVIATION...MVFR CONDITIONS WILL CONTINUE AT MOST PLACES THROUGH
THE DAY...THOUGH THERE IS A TEMP BREAK IN THE LOWER CLOUDS
AFFECTING SOUTHERN AIRPORTS (AUW/CWA/GRB) VERY EARLY THIS AM. OCNL
IFR WITH LOWER CIGS AND VSBY ASSOCIATED WITH SNOW SHOWERS. BEST
CHANCE IN FAR EASTERN PART OF FORECAST AREA ASSOCIATED WITH LAKE
ENHANCED SNOWS.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR WIZ022-
040-050.
&&
$$
ECKBERG
