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000
FXUS63 KGRB 041215
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
615 AM CST WED DEC 4 2013

UPDATED AVIATION PORTION FOR 12Z TAF ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND THURSDAY
ISSUED AT 427 AM CST WED DEC 4 2013

FOCUS IS ON PCPN TYPES AND AMOUNTS TODAY...THEN FALLING
TEMPERATURES TONIGHT AND THU.

MODELS ARE IN BETTER AGREEMENT TONIGHT...USED A BLEND...LEANING A
BIT MORE ON ECMWF FOR THIS PERIOD. MADE EARLIER CHANGE TO
HEADLINES WITH ISSUANCE OF WINTER WEATHER ADVISORY FOR CENTRAL WI
AS TEMPERATURES NOT MOVING ABOVE FREEZING...ACTUALLY DROPPED. LIGHT
PCPN CONTINUES TO LIFT NORTH INTO CWA. CALLS TO PORTAGE AND WOOD
COUNTIES INDICATED ICING ISSUES ON ROADS. LOOKING FOR
TEMPERATURES TO MOVE ABOVE FREEZING MID MORNING.

RADAR MOSAIC SHOWING AREA OF SNOW MAKING BEELINE FOR NORTH CENTRAL
WI THIS MORNING WITH RAP BRINGING IT INTO CWA AROUND 6AM.
TEMPERATURE PROFILES SUGGEST MOSTLY SNOW OVER NORTHERN WI THROUGH
18Z...THEN START TO MIX...LIMITING SNOW TOTALS. STILL LOOKING FOR
5 TO 7 INCHES WESTERN AREAS OF VILAS...SO WILL KEEP WARNING AS IS. NO
CHANGES PLANNED FOR CURRENT HEADLINES. TO THE SOUTH...INCREASING
DEW POINTS OVER FRESH SNOW FROM PREVIOUS EVENING TO LEAD TO DENSE
FOG FORMATION...MAINLY EAST CENTRAL. MODELS A BIT FAST BRINGING
MOISTURE NORTH...SO PUSHED BACK TIMING IN GRIDS. WILL PLAY WATCH
AND SEE A BIT LONGER BEFORE ISSUING ANY HEADLINE GIVEN NUMBER OF
HEADLINES OUT RIGHT NOW.

STRONG COLD FRONT TO MOVE THROUGH TONIGHT...WITH WED MIN/THU MAX
AROUND 12Z THU. USED NON DIURNAL TREND FOR TEMPS FALLING THROUGH
THE DAY. APPARENT TEMPS ONLY IN SINGLE DIGITS ABOVE OR BELOW ZERO
FOR MUCH OF THU. BACKED OFF A BIT ON POPS FOR LAKE EFFECT SNOWS
FAR NORTH THU WITH WINDS TOO WESTERLY IN DIRECTION.

.LONG TERM...THURSDAY NIGHT THROUGH TUESDAY
ISSUED AT 427 AM CST WED DEC 4 2013

MDLS CONT TO ADVERTISE AN AMPLIFIED MEAN FLOW THAT CONSISTED OF AN
ALASKA UPR RDG...A DEEP POSITIVE-TILTED LONGWAVE TROF FROM NRN
CANADA TO THE SW CONUS AND UPR RIDGING FROM FLORIDA INTO THE WRN
ATLANTIC. THIS PATTERN TO HOLD STEADY THRU THE UPCOMING WEEKEND
BEFORE THE ALASKA RDG BREAKS DOWN AND THE UPR TROF SHIFTS INTO THE
CNTRL CONUS BY THE END OF THE FCST PERIOD. A DRY AND VERY COLD AIR
MASS TO DEVELOP OVER NE WI THRU SAT NGT BEFORE THE NEXT SYSTEM IN
THE SW FLOW ALOFT ARRIVES LATE SUNDAY INTO MON. ANOTHER SURGE OF
ARCTIC AIR TO THEN OVERSPREAD THE REGION FOR THE MIDDLE OF NEXT
WEEK WITH TEMPS 20 TO 30 DEGS BELOW NORMAL.

LARGE ARCTIC HI PRES TO EXTEND FROM BRITISH COLUMBIA SEWD INTO THE
NRN/CNTRL PLAINS THU NGT WITH AN EWD EXTENT REACHING INTO THE
GREAT LAKES. THIS WOULD BRING PARTLY CLOUDY SKIES AND UNSEASONABLY
COLD CONDITIONS TO NE WI WITH TEMPS DROPPING BELOW ZERO OVER NRN/
PARTS OF CNTRL WI...WHILE LAKESHORE AREAS DIP INTO THE UPR SINGLE
DIGITS. ADD IN A WEST WIND AT 10 TO 15 MPH AND WE ARE LOOKING AT
WIND CHILL VALUES RANGING FROM 5 BELOW TO 20 BELOW ZERO BY
DAYBREAK. WL NEED TO WATCH N-CNTRL WI FOR A POSSIBLE WIND CHILL
ADVY IF WINDS CAN REMAIN STRONG ENUF.

QUIET AND VERY COLD CONDITIONS CONT THRU FRI AS THE ARCTIC HI TO
DOMINATE THE MIDDLE OF THE COUNTRY. THIS SFC HI WL KEEP A SYSTEM
MOVING FROM THE DEEP SOUTH TO THE MID-ATLANTIC STATES ADN NOT HAVE
ANY IMPACT ON OUR WEATHER. MAX TEMPS WL NOT GET OUT OF THE SINGLE
DIGITS OVER N-CNTRL WI...WITH TEENS EXPECTED ELSEWHERE. THIS WOULD
BE ABOUT 15 DEGS BELOW NORMAL.

THE ERN FLANK OF THE ARCTIC HI EDGES INTO THE WRN GREAT LAKES
REGION FRI NGT WITH A SLIGHT DIMINISH IN WIND SPEEDS. 8H TEMPS TO
HOVER IN THE -18 TO -20C RANGE AND WITH SKY CONDITIONS OF MOSTLY
CLEAR TO PARTLY CLOUDY...TEMPS WL BE EVEN COLDER THAN THU NGT WITH
READINGS FLIRTING WITH DOUBLE DIGITS BELOW ZERO IN THE NORTH...NEAR
ZERO AROUND THE FOX VALLEY AND AROUND 5 ABOVE ZERO NEAR LAKE MI. WE
COULD AGAIN BE LOOKING AT POSSIBLE WIND CHILL ADVYS ACROSS PARTS OF
NE WI AS VALUES FALL BELOW THE -20 DEG THRESHOLD. THE ARCTIC HI IS
FCST TO STRETCH FROM THE NRN HI PLAINS THRU THE GREAT LAKES ON
SAT...THEREBY PROVIDING FOR ANOTHER MOSTLY SUNNY TO PARTLY CLOUDY
DAY WITH TEMPS WELL BELOW NORMAL. IN FACT...MAX TEMPS WL NOT GET
OUT OF THE SINGLE DIGITS OVER NRN AND CNTRL WI AND ONLY IN THE 10
TO 15 DEG RANGE FOR E-CNTRL WI. THESE VALUES WOULD BE AROUND 20
DEGS BELOW NORMAL.

ATTENTION THEN TURNS TOWARD THE CNTRL CONUS LATE IN THE WEEKEND
WHERE A SYSTEM IS PROGGED TO EJECT NEWD OUT OF THE MAIN LONGWAVE
TROF. CLOUDS TO ALREADY BEGIN TO INCREASE SAT NGT...BUT QUESTIONS
REMAIN AS TO HOW FAST MOISTURE WL BE ABLE TO OVERSPREAD WI WITH
THE INITIAL DRY AIR MASS IN PLACE. EVEN WITH A STEADY INCREASE IN
ISEN LIFT THRU THE DAY...BELIEVE IT WL TAKE MOST OF SUNDAY JUST TO
SATURATE...THUS HAVE KEPT POPS ON THE LOW SIDE WITH A SLIGHT UPTICK
IN TEMPS AS 8H TEMPS `WARM` TO AROUND -14C.

AS ONE WOULD EXPECT THIS FAR OUT...THE MDLS ARE TRYING TO ZERO IN
ON THE TRACK OF THE STRENGTHENING AREA OF LOW PRES WHICH WL LIFT
NE TOWARD/INTO THE GREAT LAKES SUNDAY NGT. THE EXACT TRACK WL BE
CRUCIAL WHETHER NE WI SEES JUST LIGHT SNOW OR AN APPRECIABLE
ACCUMULATION WARRANTING A HEADLINE. HAVE RAISED POPS INTO THE HI
CHC CATEGORY FOR CNTRL WI AND LIKELY FOR ERN WI BASED ON THE MDLS
MOVING THE SFC LOW TOWARD ERN SECTIONS OF THE GREAT LAKES. WL NEED
TO WATCH THIS SYSTEM IN THE COMING DAYS AS ANY CHANGE IN STORM
TRACK WOULD AFFECT ACCUMULATION NUMBERS. THE SNOW SHOULD END MON
MORNING AS THE SFC LOW QUICKLY LIFTS NE INTO SE CANADA. ANY
ADDITIONAL ACCUMULATIONS APPEAR TO BE MINOR AT THIS POINT. THE
OTHER STORY FOR MON WL BE THE ONSET OF THE NEXT ARCTIC SURGE AS 8H
TEMPS CRASH THRU THE DAY. TEMPS MAY EASILY BE STEADY OR SLOWLY
FALL WITH LATE DAY TEMPS ALREADY DOWN INTO THE SINGLE DIGITS AND
TEENS.

THE COLDER AIR OF THE WINTER SEASON TO THEN SWEEP ACROSS THE GREAT
LAKES REGION MON NGT INTO TUE WITH 8H TEMPS PLUMMETING TO AS LOW
AS -26C. TOO MUCH OF A WESTERLY COMPONENT TO THE WIND TO BRING
LAKE EFFECT SNOWS INTO NRN WI...THUS AT LEAST A DRY FCST IS
ANTICIPATED. EXACTLY HOW COLD WE GET WL BE DETERMINED BY THE
EXTENT OF THE SNOW COVER OVER THE FCST AREA. BY TUE MORNING...SUB-
ZERO TEMPS COULD COVER ALL BUT THE LAKESHORE AREAS WITH MAX TEMPS
ON TUE PERHAPS NOT GETTING ABOVE ZERO OVER N-CNTRL WI.
&&

.AVIATION...FOR 12Z TAF ISSUANCE
ISSUED AT 544 AM CST WED DEC 4 2013

GENERALLY POOR FLIGHT CONDITIONS EXPECTED INTO THIS EVENING WITH
SNOW OR A WINTRY MIX NORTH AND FOG SOUTH. LIGHT FREEZING PCPN WILL
AFFECT CENTRAL TAF SITES THROUGH THE MORNING...THOUGH SURFACE
TEMPERATURES ARE EXPECTED TO CLIMB TO ABOVE FREEZING MID MORNING.
BRISK WESTERLY WINDS EXPECTED BEHIND SYSTEM THIS EVENING AND
OVERNIGHT...WITH VISBYS/CIGS IMPROVING.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR
WIZ010>012.

WINTER WEATHER ADVISORY UNTIL 9 AM CST THIS MORNING FOR WIZ020-
021-030-031-035>037-045.

WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR WIZ018-019.

WINTER STORM WARNING UNTIL MIDNIGHT CST TONIGHT FOR WIZ005.
&&

$$

SHORT TERM.....TE
LONG TERM......KALLAS
AVIATION.......TE