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000
FXUS63 KGRB 231727
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1127 AM CST FRI JAN 23 2015

UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND SATURDAY
ISSUED AT 408 AM CST FRI JAN 23 2015

PCPN TRENDS/TYPE WILL BE THE MAIN FCST CONCERN.

TOUGH FCST TODAY...DUE TO A DRY WEDGE IN THE 850-700 MB LAYER...
AND A WEAK WARM LAYER ALOFT (CURRENTLY OVER FAR NORTHERN WI) THAT
WILL SAG SOUTH ACROSS THE REGION DURING THE DAY. A WINTRY MIX OF
PCPN HAS BEEN FALLING OVER NORTHERN MN EARLY THIS MORNING...BUT
HAS BEEN UNABLE TO WORK ITS WAY INTO NORTH CENTRAL WI DUE TO
LINGERING DRY AIR. AT LEAST A BRIEF PERIOD OF SATURATION SHOULD
OCCUR OVER NORTH CENTRAL AND FAR NORTHEAST WISCONSIN THIS MORNING
AND EARLY AFTERNOON...AS A S/W TROF AND THE RRQ OF AN UPPER JET
IMPACT THE REGION. HOWEVER...A DEEPER DRY LAYER AND WEAKER FORCING
OVER CENTRAL AND EAST CENTRAL WI WILL LEAD TO SLOWER PCPN
DEVELOPMENT AND LESS QPF. HAVE ADJUSTED POP TRENDS TO SLOW DOWN
THE PCPN ARRIVAL IN OUR SOUTHERN COUNTIES UNTIL THIS AFTERNOON...
AND IT IS POSSIBLE THAT MEASURABLE PCPN MAY NOT MAKE IT TO OUR
SOUTHERN CWA BORDER. PCPN TYPE SHOULD INITIALLY BE MAINLY
SNOW/SLEET...WITH TEMPERATURES IN THE WARM LAYER ONLY 0 TO +2 C.
THE WARM LAYER ALOFT SHOULD ERODE BY MID TO LATE AFTERNOON...AND
TEMPERATURES SHOULD RISE TO A LITTLE ABOVE FREEZING...SO PCPN
IS EXPECTED TO TRANSITION TO A LIGHT RAIN/SNOW MIX. HIGH
TEMPERATURES SHOULD BE IN THE 30S.

SOME PATCHY FREEZING DRIZZLE MAY LINGER INTO THE EARLY EVENING
AS REMAINING PCPN TAPERS OFF. NW FLOW OFF LAKE SUPERIOR MAY
PROVIDE ENOUGH MOISTURE TO CONTINUE A THREAT OF FZDZ IN FAR
NC WI OVERNIGHT. CLOUDS WILL KEEP TEMPS FROM DROPPING OFF MUCH...
WITH LOWS EXPECTED TO REMAIN IN THE 25 TO 30 RANGE.

ON SATURDAY...PATCHY FZDZ OR FLURRIES SHOULD CONTINUE IN FAR
NC WI...WITH MOSTLY CLOUDY SKIES ANTICIPATED ELSEWHERE. HIGHS
WILL BE IN THE 30S.

.LONG TERM...SATURDAY NIGHT THROUGH THURSDAY
ISSUED AT 408 AM CST FRI JAN 23 2015

SAME OLD STORY AS 500MB RIDGE ACROSS WESTERN NORTH AMERICA AND
EASTERN NORTH AMERICAN TROUGH WILL DOMINATE THE WEATHER PATTERN
DURING THE PERIOD. RIDGE WILL FLATTEN SOME EARLY NEXT WEEK...
THEN BUILD AGAIN AND RETROGRADE BY THE END OF THE WORK WEEK
AS EAST COAST TROUGH DEEPENS. THIS SHIFT IN THE PATTERN WILL
OPEN THE DOOR FOR THE TRUE ARCTIC AIR TO PLUNGE SOUTHWARD INTO
THE GREAT LAKES REGION LATE NEXT WEEK INTO THE WEEKEND OF
JAN 31/FEB 1.

CLIPPER SYSTEM FOR SATURDAY NIGHT/SUNDAY STILL PROBLEMATIC IN
WHERE AXIS OF HEAVIEST SNOWS WOULD OCCUR. ECMWF HAS TRENDED
SOUTH COMPARED TO THE CANADIAN AND WRF MODEL. GFS MODEL HAS COME
IN CLOSER TO THE ECMWF QPF SOLUTION...THUS WILL SHIFT THE AXIS
OF THE HEAVIEST SNOWFALL TOTALS INTO CENTRAL WISCONSIN. GFS
ENSEMBLE MEMBERS ALSO SUPPORTED MORE CONFIDENCE IN THE SOUTHERN
SOLUTION. ALSO...EASTERLY FLOW OFF THE CANADIAN HIGH PRESSURE SYSTEM
TO THE NORTH OF THE STATE MAY REALLY LIMIT TOTALS ACROSS THE FAR
NORTHEAST PORTION OF WISCONSIN. THESE TRENDS WERE REFLECTED IN THE
SNOW CHANCES ACROSS THE REGION ALONG WITH QPF/SNOWFALL TOTALS.
HOWEVER...IF WRF/CANADIAN ARE CORRECT...POPS/SNOWFALL TOTALS
WOULD NEED TO BE SIGNIFICANTLY INCREASED ACROSS THE NORTHEAST HALF
OF THE FORECAST AREA. COLDER AND DRIER AIR WILL WORK INTO THE
REGION ON SUNDAY...BRINGING AN END TO ANY SNOW CHANCES FROM NORTH
TO SOUTH.

ANOTHER WEAK SYSTEM WILL DROP SOUTHEAST INTO THE AREA...BRINGING
A CHANCE OF LIGHT SNOW MONDAY AFTERNOON AND MONDAY NIGHT. IT IS
ALSO POSSIBLE THAT SOME LIGHT LAKE EFFECT SNOW SHOWERS OR FLURRIES
ARE POSSIBLE ALONG THE LAKE MICHIGAN SHORELINE AT SOME POINT DURING
THIS PERIOD. ON WEDNESDAY...IT WILL BECOME BLUSTERY OR WINDY AHEAD
OF APPROACHING COLD FRONT. PER COORDINATION WITH SURROUNDING OFFICES...
RAISED MAX TEMPERATURES ON THIS DAY. THE TRUE ARCTIC FRONT WILL MOVE
INTO NORTHERN WISCONSIN FRIDAY AFTERNOON...AND THEN SOUTH OF THE
AREA BY SATURDAY AFTERNOON. ARCTIC AIR WILL BE FIRMLY IN PLACE BY
THE WEEKEND OF JAN 31/FEB 1.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1127 AM CST FRI JAN 23 2015

A BAND OF LIGHT SNOW...POSSIBLY MIXED WITH SLEET...WILL BE MOVING
ACROSS CENTRAL AND NORTHEAST WISCONSIN THIS AFTERNOON.  VSBYS MAY
BRIEFLY FALL TO MVFR BUT AM NOT CONFIDENT TO INCLUDE IN TAFS AT THE
MOMENT.  ANY LIGHT PRECIP WILL HAVE EXITED THE TAFS SITES BY
00Z...THEN MVFR STRATUS IS EXPECTED TO MOVE SOUTHEAST ACROSS THE TAF
SITES THIS EVENING.  SOME UNCERTAINTY IN REGARDS TO HOW SOON THIS
STRATUS WILL ARRIVE AS THE LATEST MODEL RUNS ARE QUITE AGGRESSIVE
WITH THE FORWARD MOTION OF THE STRATUS WHICH DOES NOT QUITE MATCH
OBSERVATIONS.  WILL INCLUDE A SHORT PERIOD OF SCT CONDITIONS BEFORE
THE MVFR STRATUS ARRIVES.  ONCE IT DOES...BKN TO OVC CONDITIONS ARE
EXPECTED TO REMAIN THROUGH THE DURATION OF THE FORECAST.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM.....KIECKBUSCH
LONG TERM......ECKBERG
AVIATION.......MPC