FXUS63 KGRB 232207
AFDGRB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
407 PM CST WED DEC 23 2009
.SHORT TERM...TONIGHT THROUGH THURSDAY. LEFT EXIT REGION OF 500MB
JET STREAK APPROACHES THE AREA TONIGHT AND INDUCES VERTICAL
MOTION. THIS COMBINED WITH STRONG LOW LEVEL WARM ADVECTION SHOULD
PRODUCE A FEW INCHES OF SNOW OVER THE SOUTHERN HALF OF THE FORECAST
AREA. 850 MB AND BOUNDARY LAYER TEMPERATURES SHOULD STAY BELOW 0C
SO EXPECT MAINLY SNOW TONIGHT. THERE COULD BE SOME SLEET MIXED IN
THURSDAY AFTERNOON AS ELEVATED WARM LAYER APPROACHES...AND THERE
COULD BE A LITTLE RAIN THURSDAY AFTERNOON ALONG THE LAKE MICHIGAN
SHORE.
.LONG TERM...THU NGT THRU NXT WED. LRG STORM TO IMPACT NE WI THRU
SAT NGT BEFORE WEAKENING AND SLIDING EAST TOWARD THE LATTER HALF
OF THE WEEKEND. WL SEE MIXED PCPN FINALLY TRANSITION TO ALL SNOW
BY FRI AFTERNOON AS COLDER AIR WRAPS INTO WI AROUND THE STORM.
STILL APRS THAT CNTRL/FAR NE WI TO SEE THE MOST SNOW WITH BLUSTERY
CONDITIONS THRU XMAS DAY. OTHER THAN THE PASSAGE OF A WEAK CDFNT
NXT MON NGT/TUE...THE FIRST PART OF NXT WEEK LOOKS QUIET WITH NEAR
SEASONAL TEMPS.
STILL A LOT OF QSTNS WITH REGARDS TO PCPN TYPE THU NGT AS MDLS
HAVE ENUF DIFFERENCES TO CAUSE MAJOR HEADACHES. AT THE CENTER OF
THE PBLM IS THE PHASING THAT TAKES PLACE BETWEEN THE MAIN SYSTEM
AND A NRN STREAM SHRTWV TROF DIGGING SE INTO THE CNTRL PLAINS.
EXACTLY HOW THESE TWO FEATURES INTERACT WL DETERMINE THE RAIN/SNOW
LINE AND WHERE THE HEAVIER SNOW WL OCCUR. THE NAM STILL APRS TO
PULL TOO MUCH WARM AIR INTO NE WI...WHILE THE GFS APRS TOO FAR
SOUTH WITH THE SYSTEM THUS TOO COLD ALOFT. HAVE FOLLOWED THE 09Z
SREF AS A GOOD COMPROMISE WHICH BRINGS ALL SNOW TO N-CNTRL WI...
A MIX OF FREEZING RAIN/SLEET/SNOW FROM CNTRL TO FAR NE WI AND THEN
PRIMARILY ALL RAIN TO E-CNTRL WI.
THE TWO WEATHER FEATURES CONSOLIDATE OVR CNTRL IA ON FRI WITH A
POTENT LOOKING SHRTWV LIFTING NWD INTO WI DURING THE DAY. THIS
INCREASED FORCING PLUS THE NWD ROTATING OCCLUDED FNT INTO SRN WI
WL HELP DVLP AN INCREASE IN QPF ACROSS THE FCST AREA ESP FROM
CNTRL TO FAR FAR NE SECTIONS OF THE STATE. PCPN TYPE CONTS TO BE
THE MAIN FCST PBLM ESP FRI MORNING BEFORE COLDER AIR WRAPS INTO
THE AREA FROM THE SOUTH AND SWITCHES ANY LIQUID TO ALL FROZEN. IN
FACT...FCST SNDNGS SHOW AN INFLUX OF DRY AIR ALOFT IN THE
AFTERNOON WHICH WOULD LEAD TO AREAS OF FRZ DRZL WITH THE SNOW. FOR
NOW...PREFER TO MENTION MAINLY SNOW (MIXED WITH A LITTLE SLEET)
N-CNTRL...A HODGE-PODGE OF SNOW/SLEET CNTRL -> FAR NE WI...RAIN/SNOW
MIX E-CNTRL AND ALL RAIN AT THE LKSHR IN THE MORNING.
THAT INFLUX OF DRIER AIR ALOFT GRADUALLY MOISTENS BACK UP FRI
NGT...THUS AFT SOME AREAS OF FRZ DRZL FRI EVENING...PCPN TYPE
SHOULD GO BACK TO ALL LGT SNOW AROUND THE MIDNGT HR. OTHERWISE...
THE NEARLY VERTICALLY STACKED SYSTEM REMAINS PARKED OVR CNTRL IA
WITH PIECES OF SHRTWV ENERGY ROTATING AROUND THRU WI. HAVE KEPT
THE LIKELY POPS WITH AN ADDL INCH OR TWO OF ACCUMULATION PSBL.
THE STORM BECOMES VERTICALLY STACKED AND BEGINS TO SLOWLY WEAKEN
OVR E-CNTRL IA ON SAT...BUT OBVIOUSLY WELL WITHIN PROXIMITY TO NE
WI TO KEEP LGT SNOW IN THE FCST. DO NOT ANTICIPATE ANY MAJOR QPF
AMTS AS GULF MSTR TO HAVE LONG SHIFTED EAST TOWARD THE EAST COAST.
THAT BEING SAID...EXPECT ANOTHER INCH OR TWO OF ACCUMULATION OVR
MOST OF THE FCST AREA. WE WL HAVE TO WATCH THE LKSHR COUNTIES AS A
S-SE WND MAY BRING A BIT OF LK ENHANCEMENT INTO THE PICTURE WITH
8H TEMPS DOWN TO -11C. LGT SNOW TO PERSIST RIGHT THRU SAT NGT AS
THE STORM BEGINS TO FINALLY MAKE AN EWD MOV. THE WEAKENING TREND
CONTS...THUS ADDL SNOW ACCUMULATIONS SHOULD BE MINIMAL (MAYBE
ANOTHER INCH?). NE WI TO GET ON THE BACKSIDE OF THE STORM BY
SUNDAY LEADING TO MORE OF A LGT SNOW SHWR/FLURRY TYPE OF WEATHER.
HAVE RAISED POPS TO CHC WITH HIGHER VALUES EAST WHERE LINGERING
CYCLONIC FLOW EXISTS.
SPLIT FLOW ACROSS THE CONUS TO START THE WORK WEEK WITH MORE
ACTIVE SRN STREAM FOCUSED OVR THE SW CONUS AND WEAKER NRN STREAM
DIVING SE FROM CNTRL CANADA THRU THE GREAT LKS. A CDFNT DROPS
SOUTH TOWARD NRN SECTIONS OF THE GREAT LKS ON MON...BUT NOT HAVE
ANY AFFECT ON US YET. HI PRES OVR THE CNTRL PLAINS WL SEND ENUF
DRY AIR INTO WI TO GO WITH MAINLY DRY CONDITIONS. THERE COULD BE A
FEW LK EFFECT SNOW SHWRS FOR VILAS COUNTY...HOWEVER 8H TEMPS ARE
NOT THAT COLD SO ANY SNOW WL BE LGT. DO NOT ANTICIPATE ANY PCPN
WITH THE FROPA MON NGT AS MSTR IS SEVERELY LACKING. INSTEAD...WL
WATCH UPR HGTS BUILD INTO THE RGN AS AN UPR RDG APPROACHES. HI
PRES AT THE SFC TO DOMINATE THE ERN THIRD OF THE CONUS THRU TUE...
SO DRY CONDITIONS TO PREVAIL WITH TEMPS CLOSE TO NORMAL. PLENTY OF
QSTNS THEN FOR WED AS MDLS DISAGREE WITH THE DEPTH OF THE NXT
SYSTEM COMING OUT OF THE PLAINS. TOO MUCH OF A DIFFERENCE TO GET A
GOOD HANDLE ON...THUS FOLLOWED HPC'S PREFERENCE OF THE ECMWF WHICH
COULD BRING SOME LGT SNOW INTO NE WI ON WED.
&&
.AVIATION...SNOW WILL BE ARRIVING IN CENTRAL AND EAST CENTRAL
WISCONSIN TONIGHT. MVFR CIGS WILL GRADUALLY LOWER TO IFR ALONG
WITH IFR VSBYS IN SNOW. MVFR CIGS EXPECTED IN NORTHERN WISCONSIN
OVERNIGHT BUT SNOW AND IFR CONDITIONS WILL MOVE INTO THAT AREA
DURING THE DAY.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM CST
THURSDAY FOR WIZ038>040-048>050.
WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 PM CST FRIDAY
FOR WIZ020-030-031-035>037-045.
WINTER STORM WARNING FROM 6 PM THURSDAY TO 6 PM CST FRIDAY FOR
WIZ011>013-018-019-021.
WINTER WEATHER ADVISORY FROM 6 PM THURSDAY TO 6 PM CST FRIDAY
FOR WIZ005-010-073-074.
&&
$$
RDM/KALLAS
