Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 212038
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
238 PM CST FRI NOV 21 2014

FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE

.SHORT TERM...TONIGHT AND SATURDAY
ISSUED AT 237 PM CST FRI NOV 21 2014

PLENTY OF POTENTIAL FCST PITFALLS OVER THE NEXT 24 HOURS AS THE
SURGE OF WARMER AIR LEADS TO PCPN TYPE ISSUES LATE TNGT THRU SAT
MORNING. PART OF THE PROBLEM IS THAT EVEN THO TEMPS WL FINALLY GET
ABOVE THE FREEZING MARK ON SAT...ROAD TEMPS ARE STILL BELOW
FREEZING...THUS LEADING TO ICY SPOTS AND TRAVEL PROBLEMS.

THE 20Z MSAS SFC ANALYSIS INDICATED A STRONG AREA OF HI PRES
CENTERED OVER SRN OHIO...SENDING S-SW WINDS INTO WI AND ALLOWING
TEMPS TO FINALLY BEGIN TOWARD. STRONG LOW PRES NEAR LAKE WINNIPEG
COUPLED WITH THE OHIO HI PRES...WAS PRODUCING GUSTY WINDS ACROSS
NE WI. WHILE THE WARMER AIR ALOFT WAS GENERATING SOME MID CLOUDS
OVER THE WRN GREAT LAKES...ATTENTION IS FOCUSED OVER THE MID-MS
VALLEY WHERE THE LEADING EDGE OF LOW CLOUDS/TRAILING PCPN WAS
LOCATED. THIS AREA CLOUDS/PCPN WAS MAKING A BEE-LINE TOWARD THE
GREAT LAKES AND SHOULD ARRIVE LATER THIS EVENING.

AN INCREASING SW LOW-LEVEL JET (TO 50 KTS) WL QUICKLY TRANSPORT
THIS WARM/MOIST GULF AIR TOWARD WI TNGT. INITIALLY...FCST
SOUNDINGS AND TIME SECTIONS CONT TO SHOW A VERY DRY AIR MASS OVER
WI...THUS EXPECT TO SEE JUST THE INCREASE IN CLOUDS THIS EVENING.
AFTER MIDNGT...ENUF WAA AND SATURATION OF THE LOWER LEVELS OF THE
ATMOSPHERE WL OCCUR TO ALLOW PCPN TO DEVELOP FROM SW TO NE ACROSS
THE FCST AREA. A STUBBORN DRY LAYER ALOFT (AROUND 10K FT) WL
PREVENT ICE FROM BEING INTRODUCED INTO THE CLOUD...THEREFORE WITH
A SUPERCOOLED LAYER EXPECTED...WE SHOULD SEE FREEZING DRIZZLE
DEVELOP OVER NE WI. THE BEST LIKELIHOOD OF A MORE WIDESPREAD
FREEZING DRIZZLE EVENT (OR FREEZING RAIN) WOULD BE E-CNTRL WI
WHERE THE LIFT IS THE STRONGEST. CONFIDENT ENUF NOW TO ISSUE A
FREEZING RAIN ADVY SOUTH OF A LINE FROM WAUTOMA TO KEWAUNEE AND
WL ISSUE A SPS FOR THE REST OF NE WI STATING THE POTENTIAL FOR
SLICK ROADS/SIDEWALKS LATE TNGT INTO SAT MORNING. MIN TEMPS SHOULD
OCCUR EARLY THIS EVENING WITH READINGS SLOWLY RISING THRU THE NGT.

FREEZING RAIN OR FREEZING DRZL WL CONT INTO SAT MORNING AND
GRADUALLY CHANGEOVER TO LIGHT RAIN OR DRZL LATE SAT MORNING/EARLY
SAT AFTERNOON AS WARMER AIR FINALLY REACHES THE SFC. THE PCPN IN
GENERAL SHOULD DIMINISH FROM WEST TO EAST AS THE BEST LIFT SHIFTS
EAST AND THE LOW-LEVEL JET WEAKENS. TEMPS ARE FCST TO REACH NORMAL
LEAVELS FOR THE FIRST TIME SINCE NOVEMBER 10TH WITH READINGS
RANGING FROM THE MID 30S N-CNTRL WI...TO AROUND 40 DEGS E-CNTRL
WI.

.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY
ISSUED AT 237 PM CST FRI NOV 21 2014

STRONG STORM EXPECTED TO MOVE ACROSS THE REGION LATE IN THE WEEKEND
INTO MONDAY...THEN TURNING MUCH COLDER BY THE MIDDLE TO END OF NEXT
WEEK.

MODELS CONTINUE TO SURGE THE WARM AIR NORTHWARD SATURDAY NIGHT WITH
TEMPERATURES EVEN ACROSS THE FAR NORTH APPROACHING 40. WILL STILL
HAVE FREEZING DRIZZLE OR LIGHT FREEZING RAIN. THE GROUND IS UNUSUALLY
COLD FOR THIS TIME OF YEAR DUE TO THE RECENT COLD SNAP. THE MILD
AIR WILL BE IN PLACE ACROSS THE ENTIRE REGION ON SUNDAY. AREAS OF
FOG WILL DEVELOP LATE SATURDAY NIGHT AND CONTINUE INTO SUNDAY
EVENING. HIGHS WILL BE MAINLY IN THE 40S.

FOR SUNDAY NIGHT/MONDAY MORNING...MODELS CONTINUE THE SLOWER TREND
OF CHANGING THE PRECIPITATION OVER TO ALL SNOW...AND WOULD NOT OCCUR
UNTIL AFTER 12Z ALONG THE LAKESHORE. TEMPERATURES ON MONDAY WILL FALL
THROUGH THE DAY WITH OCCASIONAL LIGHT SNOW OR FLURRIES. THERE IS STILL
POTENTIAL FOR A SIGNIFICANT LAKE EFFECT SNOW ACCUMULATION ACROSS NORTHWEST
VILAS COUNTY MONDAY AFTERNOON INTO MONDAY NIGHT ON TOP OF THE SYNOPTIC
SNOW. TOO EARLY TO DETERMINE AMOUNTS UNTIL BETTER HANDLE ON 850MB WINDS
OFF THE LAKE. CONTINUED CHANCES FOR SNOW INTO TUESDAY AS SYSTEM
PULLS AWAY.

MODELS CONTINUE TO SHOW CLIPPER SYSTEM MOVING ACROSS THE REGION ON
WEDNESDAY. ECMWF HAD A MORE SUBSTANTIAL SYSTEM FOR THIS PERIOD...BUT
HAS BACKED OFF. THE CANADIAN ON THE OTHER HAND IS MORE BULLISH AND
SIMILAR TO THE PREVIOUS ECMWF RUN. WILL NOT MENTION IN THE HAZARDOUS
WEATHER OUTLOOK DUE TO THE LARGE UNCERTAINTY ON THE IMPACTS THIS
SYSTEM WOULD HAVE AT THE MOMENT. VERY COLD FOR THURSDAY INTO FRIDAY...
ALTHOUGH NEW ECMWF MODEL WOULD INDICATE THIS WOULD BE A BRIEF SHOT OF
ARCTIC AIR AS 850MB TEMPERATURES WARM RAPIDLY BY FRIDAY AFTERNOON.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1155 AM CST FRI NOV 21 2014

VFR CONDITIONS EXPECTED INTO THE EVENING HOURS AS AN AREA OF HI
PRES MOVES FARTHER AWAY FROM WI. AN INCREASING SW LOW-LEVEL JET
(UP TO 50 KTS) WL QUICKLY TRANSPORT WARMER/MORE MOIST AIR INTO WI
TNGT. EXPECT TO SEE A MVFR STRATUS DECK OVERSPREAD NE WI AFTER 03Z
WITH FREEZING RAIN/DRIZZLE ARRIVING SHORTLY THEREAFTER. CIGS ARE
EXPECTED TO DROP TO IFR CONDITIONS LATE TNGT INTO SAT MORNING WITH
THE FREEZING RAIN/DRIZZLE GRADUALLY CHANGING TO LIGHT RAIN OR
DRIZZLE AS WARMER AIR CONTS TO GET PUMPED INTO THE REGION. THESE
STRONG SW WINDS HAVE ALSO PROMPTED THE NEED TO MENTION LLWS IN ALL
TAF SITES FOR TNGT.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
FREEZING RAIN ADVISORY FROM 11 PM THIS EVENING TO 10 AM CST
SATURDAY FOR WIZ038>040-045-048>050.
&&

$$

SHORT TERM.....KALLAS
LONG TERM......ECKBERG
AVIATION.......AK






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