FXUS63 KGRB 150314
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
914 PM CST MON DEC 14 2009

.UPDATE...LATEST RUC ANALYSIS AND IR/WV/RADAR IMAGERY SHOW LOW
PRESSURE EXITING EASTWARD OVER THE EASTERN GREAT LAKES...AND ARCTIC
HIGH PRESSURE BUILDING SOUTHEAST OVER THE CENTRAL PLAINS. STILL
DEALING WITH WIDESPREAD LIGHT SNOW SHOWERS AND FLURRIES ACROSS
MUCH OF THE FORECAST AREA AS CYCLONIC FLOW AND MID-LEVEL MOISTURE
HAVE BEEN SLOW TO DEPART. STARTING TO SEE SOME CLEARING WORK ITS
WAY INTO WESTERN WISCONSIN...WHICH THEN SHOULD MOVE INTO THE
EASTERN HALF OF THE STATE AFTER MIDNIGHT. HAVE ENDED THE SNOW
SHOWERS AND FLURRIES A BIT EARLIER...ACROSS CENTRAL WISCONSIN
SHORTLY AFTER MIDNIGHT...AND MUCH OF EAST CENTRAL WISCONSIN AFTER
09Z.

FARTHER NORTH...FAVORABLE THERMAL PROFILES AND AMPLE MID-LEVEL
MOISTURE LED TO A BURST OF LAKE EFFECT SNOW OVER VILAS AND ONEIDA
COUNTIES. WERE RECEIVING REPORTS OF AN INCH PER HOUR SNOW ACCUM
RATES EARLIER THIS EVENING ALTHOUGH VSBYS DIDNT REALLY FALL BELOW
1SM. LOCAL LAW ENFORCEMENT IN VILAS COUNTY INDICATED LARGE SNOW
FLAKES TYPICAL OF DENDRITES WHICH ISNT ALL THAT SURPRISING GIVEN
THE THERMAL PROFILE. LATEST 03Z OBS INDICATE THE HEAVIEST SNOW
BANDS ARE SHIFTING TO THE EAST AS VSBYS HAVE IMPROVED AT ARV/RHI/IWD
OVER THE PAST HOUR. STILL DOWN TO 1 3/4SM AT LAND O LAKES...SO
WILL KEEP THE ADVISORY GOING FOR AN HOUR OR TWO LONGER. BUT WITH
CONTINUING BACKING WINDS THIS EVENING...ANTICIPATE ENDING THE
ADVISORY OVER THE NEXT HOUR...POSSIBLY TWO.

TEMPS HAVE BEEN SLOW TO COOL THIS EVENING...AND HAVE SLOWED THE
COOLING CURVE AS A RESULT. TEMPS STILL EXPECTED TO FALL NEAR ZERO OVER
CENTRAL WI LATER TONIGHT...WITH WIND CHILLS IN MINUS 15 TO 20
DEGREE RANGE.

MPC
&&

.PREV DISCUSSION...ISSUED AT 248 PM CST MON DEC 14 2009...

SHORT TERM...TNGT AND TUE. SEVERAL FCST CONCERNS TO DEAL WITH OVR
THE NXT 24 HRS RANGING FROM SNOW SHWRS AND VERY COLD WIND CHILLS
TNGT...TO HOW MUCH TEMPERATURE RECOVERY CAN WE GET ON TUE.

THE 20Z MSAS SFC ANALYSIS SHOWED WEAK LOW PRES OVR SRN LK MI WITH
A CONTINUED E-NE MOVEMENT INTO LWR MI. HI PRES WAS SITUATED OVR
THE NRN PLAINS NOSING SWD INTO THE CNTRL PLAINS. RADAR MOSAIC
INDICATED THE NARROW BAND OF HEAVIER SNOWS JUST EXITING THE SE
CORNER OF THE FCST AREA WITH LIGHT SNOWS/FLURRIES LINGERING BACK
OVR THE NRN HALF OF WI.

SYSTEM SNOWS CONT TO WIND DOWN LATE THIS AFTERNOON AS THE SFC LOW
HEADS TOWARD SRN LK HURON/SE CORNER OF ONTARIO. MORE ATTN TO BE
FOCUSED TO OUR NW WHERE A NRN STREAM SHRTWV TROF IS FCST TO
QUICKLY DROP SE INTO THE WRN GREAT LKS AFT MIDNGT. A RATHER
IMPRESSIVE SHRTWV AT THE BASE OF THE TROF WL REACH NW WI BY
DAYBREAK WITH STG Q-G FORCING. PBLM FOR PCPN IS THAT THE AIRMASS
GETS VERY DRY OVRNGT...THUS MAKING IT HARD FOR SNOW ACCUMULATIONS.
NONETHELESS...HAVE MENTIONED SCT SNOW SHWRS OR FLURRIES THRU THE
NGT FOR ALMOST THE ENTIRE FCST AREA. ONLY EXCEPTION COULD BE CNTRL
WI WHERE SNOW WOULD BE MORE ISOLATED. ANY ACCUMULATIONS WOULD BE
AROUND A HALF-INCH...THUS NOT THAT BIG OF A DEAL. COLDER AIR LAGS
JUST A BIT BEHIND THE DEPARTED SYSTEM AND IS NOT EXPECTED TO
ARRIVE TIL LATE TNGT. COLDEST READINGS PLACED OVR WRN SECTIONS OF
THE FCST AREA (SUB-ZERO)...WHILE LKSHR AREAS TO REMAIN IN THE LWR
TEENS. COMBINE THESE COLD TEMPS WITH W-NW WNDS OF 10 TO 15 MPH...
WL PRODUCE SUB-ZERO WIND CHILL VALUES. IN FACT...PARTS OF CNTRL WI
COULD SEE WIND CHILLS DROP CLOSE TO -20 DEGS. WL NOT ISSUE ANY
HEADLINES FOR THIS...BUT MENTION IN EITHER A SPS OR HWO.

SHRTWV TROF/EMBEDDED SHRTWV ZIP THRU WI TUE MORNING AND HAVE OPTED
TO KEEP DRY CONDITIONS AS A VERY DRY AND VERY COLD AIRMASS MOVS
INTO THE RGN. HARD TO SEE TEMPS BEING ABLE TO MAKE MUCH OF A
RECOVERY WITH INITIAL CAA SURGE IN THE MORNING. HAVE LIMITED THE
DIURNAL RISE TO A 5 TO 10 DEG RANGE WITH MOST LOCATIONS IN THE HI
SINGLE DIGITS OR LWR TEENS. THERE MIGHT BE A LINGERING SNOW SHWR
FOR VILAS CNTY...BUT TRAJS ARE NOT FAVORABLE FOR MUCH LK EFFECT.

LONG TERM...WEDNESDAY NIGHT THROUGH NEXT MONDAY. 

PATTERN DOMINATED BY BLOCKING HIGH OVER THE GREENLAND/ICELAND
REGION AND BUILDING RIDGE OVER THE WEST COAST. THAT LEAVES
TROUGHING OVER CENTRAL PORTION OF THE U.S. WEAK SYSTEMS MOVING
THROUGH NORTHWEST FLOW OVER AREA MAY GIVE US CHANCE FOR LIGHT SNOW
OR FLURRIES FROM TIME TO TIME BUT NO SIGNIFICANT SYSTEM SEEN FOR
EXTENDED AT THIS TIME. TRYING TO TIME THESE WEAK SYSTEMS TO BE PROBLEM.

CANADIAN HIGH PRESSURE TO CONTINUE TEMP TRENDS WELL BELOW NORM
EARLY IN PERIOD...MODERATING BACK TO NEAR NORMAL LEVELS ON
THURSDAY. BY THE WEEKEND...NORTHWEST FLOW SETS UP OFF LAKE
SUPERIOR FOR EXTENDED PERIOD OF LAKE EFFECT. HEAVIEST SEEN TO BE
FROM SAT NIGHT INTO SUNDAY WITH INVERSION HEIGHTS NEAR 5K AND LAKE
INDUCED CAPE VALUES AROUND 500/MODERATE INSTABILITY.

AVIATION...MVFR CONDITIONS ARE EXPECTED TO IMPROVE TO VFR THIS
EVENING. VFR CONDITIONS SHOULD MAINLY PREVAIL OVRNGT...ALTHO SCT
SNOW SHWRS MAY LWR EITHER CIGS OR VSBYS BACK TO MVFR FOR A SHORT
TIME AS A SHRTWV TROF MOVS THRU. HI PRES TO BUILD INTO THE RGN ON
TUE WITH VFR CIGS/VSBYS EXPECTED.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
LAKE EFFECT SNOW ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR WIZ005.

&&

$$