000
FXUS63 KGRB 031024
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
424 AM CST TUE DEC 3 2013

FORECAST DISCUSSION FOR ROUTINE MORNING FORECAST ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND WEDNESDAY
ISSUED AT 423 AM CST TUE DEC 3 2013

FORECAST UNCERTAINTY RATHER HIGH ATTM AS MODELS CONTINUE TO WAFFLE
ON TRACK OF LOW PRESSURE WED INTO WED NIGHT.

INITIAL BAND OF SNOW ASSOCIATED WITH WAA/SHORT WAVE MOVING THROUGH
STATE IS CURRENTLY LOCATED OVER NORTHEAST HALF OF CWA. AMOUNTS
FAIRLY CONSISTENT AS BAND MOVED THROUGH...WITH LESSER AMOUNTS IN
THE EAST WITH SLOW START GIVEN INFLUX OF DRIER AIR AND WARMER
TEMPS. MODELS SUPPORT TREND SEEN IN OBSERVATIONS FOR SWITCH OVER
TO DRIZZLE OR FREEZING DRIZZLE AS UPPER MOISTURE MOVES OUT.
TEMPERATURES THROUGHOUT CWA JUST BELOW OR JUST ABOVE
FREEZING. AS DRIZZLE FALLING ON SNOW AND SURFACES NEAR FREEZING
IMPACTS EXPECTED TO BE MINIMAL. CURRENT SPS/FORECAST COVERS.

ATTENTION ON NEXT ROUND THIS EVENING AND AGAIN LATER WED. DEEPER
MOISTURE TO RETURN LATE THIS AFTERNOON AS WEAK WAVE MOVES TO
SOUTH OF REGION COMBINED WITH CONTINUED WAA TO LEAD TO HIGH POPS
FOR PCPN. TEMP PROFILES SUGGEST MAINLY LIGHT SNOW...THOUGH LOW
LEVEL/SFC TEMPS SOUTH AND EAST WOULD POINT TO RAIN OR MIX.

MAIN LOW TO LIFT NORTHEAST OUT OF IOWA ON WED. AGAIN TRACK IS VERY
UNCERTAIN WITH UKMET AND LATEST EC SHIFTING FURTHER WEST. NCEP
MODELS OUTLIERS WITH FASTER SPEED AND OR FURTHER EAST TRACK. TEMP
PROFILE ON EC SUGGESTS RAIN MIXING IN OVER NORTH CENTRAL. WITH
UNCERTAINTY AM NOT COMFORTABLE WITH ADDING ANY HEADLINES ATTM.
HAVE GONE CONSERVATIVE WITH AMOUNTS WED AFTERNOON...WHICH WOULD
LIKELY LEAD TO ADVISORY CONDITIONS.

.LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY
ISSUED AT 423 AM CST TUE DEC 3 2013

MEAN FLOW THRU THE UPCOMING WEEKEND TO BE DOMINATED BY A POSITIVE-
TILTED LONGWAVE TROF FROM CNTRL CANADA TO THE SW CONUS WITH UPR
RIDGING OVER THE SE CONUS. THIS PATTERN WOULD KEEP A SW FLOW ALOFT
OVER WI WITH ONE SYSTEM JUST EXITING THE GREAT LAKES AND A
POTENTIAL FOR TWO OTHER SYSTEMS TO POSSIBLY IMPACT OUR WEATHER
LATE IN THE WEEK/EARLY NEXT WEEK. THE OTHER MAIN ISSUE IS THE
ARCTIC INTRUSION WHICH MAY BE DELAYED BY A DAY DEPENDING ON WHICH
MDL YOU BUT INTO. NEVERTHELESS...TEMPS WL DIP TO VALUES NOT SEEN
OVER NE WI SINCE MID-FEBRUARY.

UNCERTAINTIES REGARDING THE TRACK OF THE SFC LOW CONT INTO WED NGT
AS THE SHORT-TERM MDLS DISAGREE NOT ONLY ON THE TRACK...BUT ALSO
THE FORWARD SPEED. NAM/GFS ON THE FAST SIDE WHILE THE GEM/UKMET/
ECMWF ON THE SLOW SIDE. TRENDS HAVE BEEN THAT THE SFC LOW WL
EVENTUALLY TRACK THRU THE HEART OF WI (FROM SW THRU NE WI)...SO WL
HEDGE THE FCST IN THAT DIRECTION. FAVOR THE SLOWER MOVEMENT AS
WELL DUE TO HI PRES ACROSS SE CANADA ACTING AS AN INITIAL BLOCK...
THUS MAY NEED TO CARRY A RAIN/SNOW OR EVEN ALL RAIN INTO WED
EVENING BEFORE THE CDFNT BLASTS THRU AND SWITCHES EVERYTHING TO
ALL SNOW. MAY ALSO NEED TO RAISE POPS/SNOW AMOUNTS ACROSS THE
NORTH AS A SLOWER MOVEMENT WOULD KEEP FAVORABLE LIFT/FORCING
LONGER THAN ORIGINALLY THOUGHT. CAN EASILY SEE AN ADDITIONAL 2 TO
4 INCHES OF SNOW OVER THE NORTH...BUT DUE TO THE UNCERTAINTY STILL
IN PLAY...WL HOLD OFF ON ANY HEADLINE. HAVE KEPT MIN TEMPS ON THE
WARMER SIDE OF GUIDANCE DUE TO THE SLOWER MOVEMENT OVERALL WITH
THE COLDEST OF THE INCOMING AIR MASS STILL WELL TO OUR WEST.

THE SYSTEM LIFTS INTO SE CANADA ON THU AND PULLS COLDER AIR INTO
WI...ALTHO THE BITTERLY COLD AIR TO REMAIN OVER THE PLAINS AS THE
ARCTIC HI PRES TO BUILD MORE SOUTH THAN EAST OVER THE CNTRL CONUS.
EXPECT MAINLY DRY CONDITIONS OVER A VAST MAJORITY OF NE WI WITH
ONLY VILAS CNTY POTENTIALLY SEEING A FEW SNOW SHWRS AS THE COLDER
AIR MASS MOVES OVER LAKE SUPERIOR. WINDS TO HAVE TOO MUCH OF A
WESTERLY COMPONENT...THUS KEEPING MOST OF THE SNOW NORTH OF THE MI
BORDER. DO NOT ANTICIPATE MUCH OF AN UPWARD RISE IN TEMPS ON THU
AND MAY ACTUALLY SEE READINGS EITHER STEADY OR EVEN SLOWLY FALL.

DRY AND COLD CONDITIONS TO PREVAIL OVER THE REGION THU NGT AS THE
ARCTIC HI SETTLES INTO THE NRN ROCKIES...BUT EXTENDS EWD INTO THE
MIDWEST. THE MAIN PCPN BAND TO SET-UP FROM TX TO THE MID-ATLANTIC
STATES ALONG THE NOW-STALLED CDFNT. CRUX OF THE COLDEST AIR TO
STILL BE LOCATED TO OUR WEST...SO HAVE RAISED MIN TEMPS A COUPLE
OF DEGS. ENUF DRY AIR SHOULD BE ADVECTED INTO WI THRU FRI TO KEEP
THAT AREA OF PCPN TO OUR SOUTH AND EAST...THUS CONTINUED DRY AND
COLD CONDITIONS FOR NE WI AS THE ARCTIC HI PUSHES INTO THE PLAINS
AND EXTENDS EWD INTO THE WRN GREAT LAKES. MAX TEMPS TO BE A GOOD
15 TO 20 DEGS BELOW NORMAL FOR EARLY DEC.

THE ARCTIC HI PUSHES INTO THE UPR MS VALLEY/MIDWEST FRI NGT WITH
8H TEMPS OVER WI DROPPING TO AROUND -20C BY 12Z SAT. DESPITE
BOUNDARY LAYER WINDS REMAINING AROUND 20 KTS THRU THE NGT...THE
SHEER DEPTH OF THE ARCTIC AIR WL ALLOW MIN TEMPS TO FALL INTO THE
MID-SINGLE DIGITS ABOVE ZERO NEAR LAKE MI...TO AROUND 10 BELOW
ZERO OVER N-CNTRL WI (IF NOT 10 TO 15 BELOW ZERO IN THE TYPICAL
COLD SPOTS). AS THE SFC HI REACHES THE WRN GREAT LAKES ON SAT...
WINDS WL DIMINISH BUT TEMPS WL STRUGGLE ONLY INTO THE SINGLE
DIGITS ABOVE ZERO NORTH...10 TO 15 DEGS ACROSS E-CNTRL WI.

MDLS ARE STILL SHOWING A NEW SYSTEM (UPR TROF) DIGGING ACROSS THE
SW CONUS SAT NGT...BUT THEN DISAGREE WHEN THIS SYSTEM WL EJECT
NEWD AND POTENTIALLY IMPACT A LARGE PART OF THE CNTRL CONUS ON
SUNDAY. WHILE THE GEM HOLDS THE UPR TROF IN PLACE...THE GFS AND
ECMWF EJECT THIS UPR TROF INTO THE CNTRL/SRN PLAINS ON SUNDAY WITH
AN INITIAL SMALL CHC OF ISEN LIFT-INDUCED LIGHT SNOW OVER THE FCST
AREA. THE MDL DIFFERENCES BECOME MORE EXAGERATED HEADED INTO
SUNDAY NGT WITH THE ECMWF BRINGING MEASURABLE SNOW TO THE GREAT
LAKES AS A SFC LOW LIFTS TOWARD LWR MI. MEANWHILE...THE GFS TAKES
A MORE SRN ROUTE BY TAKING THE SFC LOW THRU THE TN VALLEY AND
HARDLY BRINGS ANY SNOW TO NE WI. HARD TO HAVE ANY CONFIDENCE IN
ANY PARTICULAR MDL AT THIS POINT...ESPECIALLY AFTER ALL THE
DISTRESS HANDLING THE BIG SYSTEM CURRENTLY AFFECTING THE REGION.
PREFER TO FOLLOW THE CONSENSUS SOLUTION WHICH ESSENTIALLY SPLITS
THE MDLS AND BRINGS A CHC POP TO NE WI SUNDAY NGT. A SLIGHT WARM-
UP IN TEMPS EXPECTED ON SUNDAY WITH MORE COLD AIR ARRIVING FOR
MON.
&&

.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1043 PM CST MON DEC 2 2013

EXPECT CIGS TO SETTLE INTO IFR/LIFR RANGE ONCE MAIN PCPN BAND
PUSHES THROUGH TNGT/TOMORROW MORNING. SOME QUESTION ON IF/WHEN
ANOTHER BAND OF PCPN WL DEVELOP. INTRODUCED THE POSSIBILITY WITH
PROB30 LATE IN THE TAFS. IT WOULD LIKELY BE SN N...AND RN/SN MIX
S.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR WIZ005-010.
&&

$$

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