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000
FXUS63 KGRB 081013
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
413 AM CST SUN DEC 8 2013

FORECAST DISCUSSION FOR ROUTINE MORNING FORECAST ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND MONDAY
ISSUED AT 412 AM CST SUN DEC 8 2013

NO REAL CHANGE TO SNOWFALL TOTALS...THOUGH HAVE SPED UP TIMING OF
ADVISORIES. LIGHT SNOW NOW SPREADING INTO SOUTHWEST WI...EXPECTED
TO START IN WOOD COUNTY AROUND 12Z. EXPECT VERY LIGHT AT
BEGINNING...WITH MORE MODERATE SNOW THIS AFTERNOON. HAVE CANCELLED
WIND CHILL ADVISORY WITH THIS ISSUANCE AS WINDS CALM AND CLOUDS
HAVE MOVED IN. FEW AREAS...RHI/ANTIGO SAW WIND CHILLS BELOW -20
DEG FOR A TIME. MANITOWISH WATERS/LAND O LAKES JUST TANKED TO -23/-22 DEGS.

LOW PRESSURE TO LIFT NORTHEAST OUT OF COLORADO TODAY PASSING
THROUGH LOWER LAKES OVERNIGHT. MAIN FORCING WILL BE
LOW-LEVEL WARM ADVECTION AND WEAK DIVERGENCE WITH UPPER JET...
UPPER-LEVEL QG FORCING WITH SHORTWAVE TO MOVE THROUGH OVERNIGHT.
CONTINUE TO SEE LIFT THROUGH FAVORABLE DENDRITIC ICE GROWTH
REGION. GIVEN EXPECTED HIGH SNOW TO LIQUID RATIO EXPECT TO SEE
FLUFFY SNOW PILE UP. HAVE TRIMMED A BIT BACK FROM THE NORTH AS
MODELS POINT TO BETTER DYNAMICS SOUTH TONIGHT.

HRRR SUGGEST CONVERGENCE ALONG LAKE/LAKE BAND FORMATION OVER
SOUTHERN LAKE MI THIS MORNING BETWEEN MKE AND SBM. THIS MAKES
SENSE GIVEN CURRENT WIND FIELDS. AS OVERALL FLOW SHIFTS TO THE
EAST SOUTHEAST BAND WEAKENS AND MOVES NORTH INTO
MANITOWOC/KEWAUNEE AND EVENTUALLY DOOR COUNTIES. CONTINUED LOCALLY
HIGHER WORDING FOR LAKESHORE COUNTIES.

SNOW WILL BE EXITING BY 12Z MONDAY. ANOTHER SHOT OF COLDER AIR TO
MOVE IN BY MON AFTERNOON BEHIND TROF MOVING THROUGH CANADA. WINDS
TO PICK UP OUT OF THE WEST. GIVEN LIGHT NATURE OF SNOW WILL CONTINUE
PREVIOUS SHIFTS BLOWING SNOW THOUGHTS.

.LONG TERM...MONDAY NIGHT THROUGH SATURDAY
ISSUED AT 412 AM CST SUN DEC 8 2013

THE WELL-ADVERTISED AMPLIFIED MEAN FLOW AT THE START OF THE PERIOD
IS STILL EXPECTED TO FLATTEN TOWARD THE END OF THE WORK WEEK...THEN
BEGIN TO RE-AMPLIFY NEXT WEEKEND. MORE RIDGING WEST/TROFFING EAST...
THUS TEMPS TO REMAIN BELOW NORMAL BY VARYING DEGS (COLDEST MID-WEEK
AND THEN NOT AS COLD AIR ARRIVES LATE). PCPN CHCS TIED TO THREE
SEPARATE WEAK SYSTEMS...HOWEVER MINIMAL ACCUMULATIONS ARE EXPECTED.

WEAK SFC RDG SLIDES ACROSS WI MON NGT AND WL BRIEFLY ALLOW FOR
SKIES TO BECOME PARTLY CLOUDY. HOWEVER...MDLS ARE CONSISTENT IN
SENDING A SMALL BUT COMPACT SHORTWAVE TROF E-SE TOWARD WRN LAKE
SUPERIOR BY 12Z TUE. CLOUDS WL INCREASE ONCE AGAIN AND THERE IS
SUFFICIENT MID-LEVEL FORCING TO GENERATE LIGHT SNOW WHICH IS
EXPECTED TO APPROACH N-CNTRL WI TOWARD DAYBREAK. DESPITE THE CLOUD
INCREASE...TEMPS WL STILL BE ABLE TO DROP TO VERY COLD LEVELS WITH
BELOW ZERO READINGS AWAY FROM LAKE MI. MAY NEED TO LOOK AT WIND
CHILL HEADLINES AS READINGS SURPASS -20 DEGS.

THIS WEAK SYSTEM TO QUICKLY MOVE ACROSS NRN SECTIONS OF THE GREAT
LAKES ON TUE AND BRING A SMALL CHC OF LIGHT SNOW MAINLY TO NRN WI.
ACCUMULATION NUMBERS CONT TO LOOK MINIMAL DUE TO A LACK OF DEEP
MOISTURE...THUS NOTHING MORE THAN AN INCH TOTAL (LOCATED NEAR THE
MI BORDER) WITH LESSER AMOUNTS FARTHER SOUTH. MAX TEMPS TO ONLY
REACH THE UPR SINGLE DIGITS/TEENS (AROUND 20 DEGS BELOW NORMAL).

A POSSIBLE FLY-IN-THE-OINTMENT HAS APPEARED FOR TUE NGT AS THE
MDLS NOW BRING A SFC WAVE ALOGN A CDFNT STRETCHED ACROSS THE SRN
SECTIONS OF THE GREAT LAKES/MIDWEST. WHILE THE VAST MAJORITY OF
LIGHT SNOW WILL PASS TO OUR SOUTH...THE NRN EXTENT OF THE PCPN
COULD REACH CNTRL/E-CNTRL WI...THUS HAVE ADDED A SLGT CHC POP TO
COMPENSATE WITH SCATTERED FLURRIES FARTHER NORTH. ANOTHER SURGE OF
ARCTIC AIR TO HAVE SETTLED OVER WI TUE NGT WITH 8H TEMPS AS LOW AS
-24C OVER NRN WI. THIS COULD SEND MIN TEMPS DOWN INTO THE DOUBLE
DIGITS BELOW ZERO ACROSS N-CNTRL WI...TO NEAR ZERO CLOSE TO LAKE
MI. IF WIND SPEEDS CAN REMAIN STRONG ENUF THRU THE NGT...WE COULD
AGAIN BE LOOKING AT WIND CHILL HEADLINES.

THIS LITTLE SNOW THREAT IS EXPECTED TO QUICKLY SHIFT EAST WED
MORNING AS THE NEXT ARCTIC SFC HI MOVES ACROSS THE NRN/CNTRL
PLAINS TOWARD THE UPR MS VALLEY/MIDWEST. SKEIS SHOULD BECOME AT
LEAST PARTLY CLOUDY (IF NOT MOSTLY SUNNY)...BUT TEMPS WL NOT
RESPOND MUCH AS THE ARCTIC AIR MASS TO BE LOCKED IN OVER THE GREAT
LAKES. MAX TEMPS MAY BE LUCKY JUST TO REACH ZERO OVER N-CNTRL
WI...WHILE THE REST OF THE FCST AREA TO ONLY REACH THE SINGLE
DIGITS ABOVE ZERO.

WED NGT IS NOW LOOKING LIKE THE COLDEST NGT DURING THIS ARCTIC
OUTBREAK WITH THE NRN EDGE OF THE SFC RDG REACHING INTO WI...
THEREBY BRINGING LIGHTER WINDS TO THE AREA. MAY NEED TO LOWER
TEMPS BY AT LEAST A FEW DEGS AND WOULD NOT BE SURPRISED TO SEE
READINGS APPROACH -20 DEGS OVER N-CNTRL WI. ANOTHER VERY WEAK
SYSTEM IS FCST TO SLIDE THRU THE MEAN W-NW FLOW ALOFT ACROSS WI ON
THU...BUT MOISTURE APPEARS TO BE VERY LIMITED...THEREFORE HAVE
OPTED TO ONLY MENTION A CHC OF FLURRIES FOR NOW.

THE FINAL WEAK SYSTEM THAT COULD IMPACT NE WI IS PROGGED TO ARRIVE
LATE THU NGT THRU FRI. THIS SYSTEM APPEARS TO HAVE BETTER MOISTURE
AVAILABILITY...THUS LOW END CHC POPS ARE NECESSARY. THE MEAN FLOW
BY FRI SHOULD HAVE DE-AMPLIFIED ENUF TO ALLOW AT LEAST SOME
MODERATION IN TEMPS AS THE AIR MASS WOULD BE MORE OF PACIFIC
ORIGIN THAN ARCTIC. MAX TEMPS ON FRI COULD ACTUALLY GET INTO THE
20S WHICHI WHILE STILL BELOW NORMAL...WL BE AT LEAST CLOSER TO
NORMAL. DO NOT HAVE A GOOD FEEL FOR NEXT SAT AS THE LONG RANGE
MDLS BEGIN TO HAVE SERIOUS ISSUES WITH THE TIMING OF VARIOUS
FEATURES MOVING THRU THE CHANGING MEAN FLOW.
&&

.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1046 PM CST SAT DEC 7 2013

VFR MID LEVEL CLOUDS WILL INCREASE FROM WEST TO EAST
OVERNIGHT. A DEVELOPING STORM SYSTEM WILL TRACK OVER THE REGION
SUNDAY INTO SUNDAY NIGHT...MVFR VSBYS AND CIGS DUE TO SNOW WILL
SPREAD FROM SOUTHWEST TO NORTHEAST SUNDAY AND CONTINUE INTO
SUNDAY NIGHT. SCATTERED IFR CIGS AND VSBYS DUE TO MODERATE SNOW
MAY OCCUR LATE SUNDAY AFTERNOON INTO SUNDAY EVENING.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 9 AM THIS MORNING TO 6 AM CST
MONDAY FOR WIZ005-010-011-018>021-030-031-035>040-045-048>050-
074.

WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 6 AM CST
MONDAY FOR WIZ012-013-022-073.
&&

$$

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