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000
FXUS63 KGRB 231735
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1135 AM CST MON FEB 23 2015

UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND TUESDAY
ISSUED AT 354 AM CST MON FEB 23 2015

THE COLDEST NIGHT OF THE WINTER SEASON SO FAR WITH LOWS OF 15 TO
35 BELOW ZERO. WILL CONTINUE WIND CHILL ADVISORIES THROUGH THE
MORNING HOURS. WARM ADVECTION WILL PRODUCE RISING TEMPERATURES
TODAY AND TONIGHT BUT IT WILL REMAIN VERY COLD. HIGHS TODAY SHOULD
BE MORE THAN 20 DEGREES BELOW NORMAL FOR THIS TIME OF THE YEAR.
SUNNY SKIES WILL GIVE WAY TO INCREASING HIGH CLOUDS BY EVENING.
STRONG LOW LEVEL JET FORECAST BY THE MODELS OVER EASTERN WISCONSIN
TONIGHT SHOULD PRODUCE GUSTY SURFACE WINDS AND SIGNIFICANT BLOWING
AND DRIFTING SNOW LATE TONIGHT AND TUESDAY. SOME LIGHT WARM
ADVECTION SNOW LIKELY LATE TONIGHT AND TUESDAY BUT AMOUNTS SHOULD
BE LESS THAN AN INCH IN MOST PLACES. TEMPERATURES TUESDAY WILL BE
THE MILDEST OF THE WEEK.

.LONG TERM...TUESDAY NIGHT THROUGH SUNDAY
ISSUED AT 354 AM CST MON FEB 23 2015

MEDIUM RANGE MODELS SHOW THE SHARP RIDGING OVER THE WEST COAST
BREAKING DOWN AND REORGANIZING OVER THE PACIFIC OCEAN EARLY THIS
WEEK. THIS WILL ALLOW FOR A MORE BROAD TROUGH OVER THE EAST...AND
A DEEPER TROUGH TO DIG BACK OVER THE WEST COAST...SETTING UP A
MORE OF A SPLIT FLOW PATTERN TOWARD NEXT WEEKEND. A WARM PUSH OF
AIR WILL ACCOMPANY THIS PATTERN SHIFT...HOWEVER IT IS UNCLEAR HOW
MUCH OF THE WARM AIR WILL MAKE IT INTO WI...AS THE ARCTIC AIR IS
LURKING JUST NORTH OF THE CANADIAN BORDER.

LINGERING LAKE EFFECT SNOW SHOWERS WILL STILL BE POSSIBLE TUESDAY
NIGHT ACROSS NORTH CENTRAL WI...HOWEVER THIS SHOULD BE MINOR WITH
LITTLE ADDITIONAL ACCUMULATIONS AS MUCH OF WESTERN LAKE SUPERIOR
IS NOW ICE COVERED. THE GUSTY WINDS WILL BE DIMINISHING THROUGH
THE EVENING HOURS AS THE PRESSURE GRADIENT LOOSENS...WINDS ALOFT
DECREASE...AND A LOW LEVEL INVERSION DEVELOPS. STILL COULD SEE
SOME BLOWING AND DRIFTING SNOW THROUGH EARLY EVENING.

A WEAK SYSTEM WILL DEVELOP ALONG THE ARCTIC FRONT WELL SW OF THE
AREA MID-WEEK. MODEL CONSENSUS KEEPS ANY SNOW ASSOCIATED WITH THIS
OUT OF THE AREA. HOWEVER...00Z GEM NOW BRUSHES SOME VERY LIGHT QPF
FROM WAUSAU TO GREEN BAY SOUTH. THIS IS LIKELY DUE TO A STRONGER
PIECE OF SHORTWAVE ENERGY...WHICH THE OTHER MODELS DO NOT SHOW.
THIS IS SOMETHING TO KEEP AN EYE ON...BUT AMOUNTS WOULD BE MINOR
EVEN IF THE GEM PANS OUT. WILL STICK WITH THE DRY FORECAST FOR
NOW. OTHERWISE...HIGH PRESSURE BUILDING SOUTH FROM CANADA WILL
EXTEND INTO THE WESTERN GREAT LAKES WEDNESDAY THEN THE HIGH WILL
SPREAD ACROSS THE AREA ON FRIDAY...BRINGING DRY WEATHER.

THE MAIN STORY WILL BE THE FRIGID TEMPS...AS THE CORE OF THE
COLDEST AIR WITH THIS SURGE SPREADS OVER THE AREA ON WEDNESDAY
PM INTO THURSDAY. HIGHS IN THE SINGLE DIGITS TO LOW/MID TEENS ARE
EXPECTED WITH LOWS BELOW ZERO. THE ARCTIC AIR MASS BEGINS TO
MODERATE ON FRIDAY AND ESPECIALLY THIS WEEKEND...BUT STILL LOOK TO
REMAIN BELOW NORMAL.

THE HIGH PRESSURE WILL SLIDE TOWARD THE EASTERN SEABOARD THIS
WEEKEND...AS A TROUGH DIGS OVER THE WEST COAST AND THE FLOW
BECOMES SW. THIS FLOW WILL PUSH IN A SLUG OF MOISTURE FROM THE
SOUTHERN PLAINS FOR THE SECOND HALF OF THE WEEKEND. MODELS IN
AGREEMENT SHOWING THE MOISTURE AND PUSH OF WARMER AIR...HOWEVER
THEY DISAGREE ON HOW FAR NORTH THE WARM AIR WILL GET...AND WHAT
KIND OF STORM WILL DEVELOP. GEM HOLD THE COLD AIR OVER THE GREAT
LAKES AND ANY STORM SYSTEM WELL SOUTH OF THE AREA...WHILE THE GFS
AND ECMWF SHOW SOME PIECES OF ENERGY PUSHING ACROSS THE AREA BY
12Z...SPREADING SNOW ACROSS THE AREA. FOR NOW WILL BUMP UP POPS
FOR SATURDAY NIGHT AND SUNDAY...BUT THIS SYSTEM AND OVERALL
PATTERN WILL LIKELY GO THROUGH SOME CHANGES AS IT GETS CLOSER SO
CONFIDENCE REMAINS LOW ON ANY ONE SOLUTION.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1134 AM CST MON FEB 23 2015

VFR CLEAR EXPECTED THROUGH THE EVENING AS CIRRUS SPREADS
ACROSS THE REGION AHEAD OF THE NEXT CLIPPER. SOUTHWEST WINDS WILL
INCREASE THROUGH THE AFTERNOON AND BECOME STRONG ENOUGH TO PRODUCE
BLOWING AND DRIFTING SNOW THIS EVENING THROUGH TUESDAY MORNING.

LIGHT SNOW WILL ARRIVE FROM NORTHWEST TO SOUTHEAST LATE TONIGHT AND
CONTINUE THROUGH MIDDAY TUESDAY BEFORE DIMINISHING/EXITING. THOUGH
THE SNOW WILL LIKELY DROP VSBYS TO IFR FOR A TIME...SNOW AMOUNTS
SHOULD BE AROUND AN INCH OR LESS IN MOST PLACES. LOW LEVEL WIND
SHEAR POSSIBLE TONIGHT WITH GUSTY SOUTHWEST SURFACE WINDS AND
SOUTHWEST WINDS OF 40 KNOTS AT 1200 FT AGL.

FIELD CREWS MAY BE NEEDED TO CLEAR SNOW DRIFTS FROM
RUNWAYS, TAXIWAYS AND RAMPS TONIGHT.

&&

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

$$

SHORT TERM.....RDM
LONG TERM......BERSCH
AVIATION.......MPC