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FXUS63 KGRB 040428
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1028 PM CST TUE MAR 3 2015

UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE

.SHORT TERM...TONIGHT AND WEDNESDAY
ISSUED AT 258 PM CST TUE MAR 3 2015

PRECIPITATION DIMINISHING QUICKLY THIS AFTERNOON...THEREFORE WILL
CANCEL THE WINTER WEATHER ADVISORY WITH THE AFTERNOON PACKAGE BY
3 PM. OTHERWISE...MUCH COLDER WEATHER WILL BE THE MAIN STORY
LATE TONIGHT AND WEDNESDAY. WIND CHILL WILL BE AROUND 20 BELOW
ZERO ACROSS NORTH-CENTRAL WISCONSIN LATE TONIGHT AND EARLY WEDNESDAY
MORNING. DECIDED TO ISSUE A SPECIAL WEATHER STATEMENT SINCE IT
WILL ONLY REACH CRITERIA FOR A FEW HOURS. CLOUDS WILL BE ON THE
DECREASE LATER TONIGHT...WITH SKIES BECOMING MOSTLY CLEAR OR EVEN
PARTLY CLOUDY AT MANY LOCATIONS.

SOME DIFFERENCES IN THE GUIDANCE VALUES FOR HIGHS WEDNESDAY. SPLIT
THE DIFFERENCE BETWEEN THE COLDER MAV AND THE WARMER MET GUIDANCE...
ALTHOUGH WENT CLOSER TO THE WARMER MET GUIDANCE AT OUR TYPICAL WARMER
SPOTS. CUMULUS FIELD SHOULD DEVELOP ON WEDNESDAY...WITH MORE CLOUDS
ACROSS THE NORTH THAN THE SOUTH.

.LONG TERM...WEDNESDAY NIGHT THROUGH TUESDAY
ISSUED AT 258 PM CST TUE MAR 3 2015

A POSITIVELY TILTED TROUGH AT 500 MB WEDNESDAY NIGHT WILL SLIDE
EAST AND PAIR WITH A RIDGE TENTATIVELY ESTABLISHING ITSELF OVER
THE WEST COAST TO RETURN NORTHWEST FLOW TO THE AREA. THIS WILL
BRING ANOTHER BATCH OF ARCTIC AIR AND MORE BITTERLY COLD
TEMPERATURES FOR THE SECOND HALF OF THE WORK WEEK. THE MIDDLE
ATMOSPHERE IS STILL EXPECTED TO KEEP SOME SEMBLANCE OF SPLIT FLOW
AS THE DISPLACED WESTERN TROUGH MOVES SOUTHEAST. SEVERAL
SHORTWAVES IN THE NORTHERN STREAM MAY IMPACT THE AREA FOR THE
WEEKEND...BUT CONCERNS ABOUT LIFT AND MOISTURE COULD LIMIT
PRECIPITATION POTENTIAL IN WISCONSIN.

WEDNESDAY NIGHT AND THURSDAY...
THE NEWEST ARCTIC AIR MASS TO INVADE THE GREAT LAKES ARE FORECAST
BY NAEFS TO BRING 850 MB TEMPS TO THE -20 TO -25C RANGE AND BELOW
THE 3RD PERCENTILE...SETTING THE STAGE FOR ANOTHER NIGHT OF
SUBZERO LOWS. HOW LOW TEMPERATURES AND WIND CHILLS CAN GO WILL BE
DETERMINED BY CLOUD COVER AND WIND SPEEDS AS SURFACE HIGH PRESSURE
COMES TO DOMINATE THE AREA. WITH MOST OF THE MOISTURE ADVECTED
INTO THE AREA EARLIER THIS WEEK EXPECTED TO BE SHUNTED EAST ALONG
WITH THE DEPARTING LOW...WEDNESDAY NIGHT SHOULD SEE
CLEARING...PARTICULARLY TOWARDS DAYBREAK. THERE MAY BE SOME LAKE
EFFECT CLOUDS AND LINGERING SNOW SHOWERS IN FAR NORTH CENTRAL
WISCONSIN...BUT THE ICE COVER ON LAKE SUPERIOR SHOULD CUT DOWN ON
THE EFFECTIVENESS OF ANY LAKE EFFECT GENERATION.
THEREFORE...ANTICIPATE A VERY COLD NIGHT WITH SUBZERO LOWS TO
RETURN TO THE AREA. THE BIGGER QUESTION IS THE STATUS OF THE
WINDS. CALM WINDS WOULD PROVIDE FOR LOWER AIR TEMPERATURES...BUT
WOULD PRECLUDE ANY NEED FOR A WIND CHILL ADVISORY. ON THE FLIP
SIDE...ENOUGH WINDS WOULD ARREST TEMPERATURES FALLS TO SOME
EXTENT...BUT WOULD MAKE THE NEED FOR A WIND CHILL ADVISORY MUCH
MORE LIKELY. THE MODELS CURRENTLY KEEP THE SURFACE HIGH RELATIVELY
CLOSE TO THE AREA CREATING A WEAKER PRESSURE GRADIENT...AND THERE
IS A TENDENCY FOR WINDS IN THE COLDEST AREA TO GO SLACK. WITH
THIS...AM OPTING FOR COLDER LOWS AND HOLDING OFF ON ANY HEADLINES.
REGARDLESS...IT WILL BE VERY COLD AND IT WOULD NOT TAKE MUCH OF AN
INCREASE IN WINDS TO MAKE WIND CHILL HEADLINES A NECESSITY.

THE SURFACE HIGH SLIDING BY THROUGH ILLINOIS THURSDAY WILL BE THE
DOMINANT WEATHER FEATURE...KEEPING SKIES MOSTLY SUNNY AND WITH
LIGHT WINDS BACKING FROM NORTHWEST EARLY TO SOUTHWEST LATER IN
THE DAY. THOUGH THE EMERGENCE OF SOUTHWEST WINDS WILL BEGIN
ADVECTION OF WARM AIR...IT WILL BE WEAK AND THE COLD START MEANS
HIGH TEMPERATURES IN THE LOWER TEENS AND ON THE ORDER OF 20
DEGREES BELOW NORMAL. LOWS THURSDAY NIGHT WILL BE NOTABLY WARMER
THAN WEDNESDAY NIGHT...BUT WILL AGAIN BE DOWN AROUND THE ZERO MARK
AND WELL BELOW NORMAL.

FRIDAY THROUGH MONDAY...
THE SURFACE HIGH CONTINUES ON INTO THE OHIO VALLEY AND THE FIRST
OF A SERIES OF SHORTWAVES MOVING THROUGH THE BROAD NORTHERN STREAM
TROUGH WILL TIGHTEN THE PRESSURE GRADIENT AND BOOST SOUTHWEST
WINDS. THE STRONGER SW WINDS WILL BOLSTER WARM AIR
ADVECTION...BRING MODERATION IN LOW LEVEL TEMPS...AND INCREASE LOW
LEVEL MOISTURE. INDEED...THURSDAY NIGHT LOWS ARE EXPECTED TO BE
RELATIVELY EARLY IN THE NIGHT WITH RISING TEMPERATURES THAT WILL
CARRY FRIDAY HIGHS TO LEVELS APPROACHING SEASONAL NORMS.

THIS LEAD SHORTWAVE AND INCREASE IN MOISTURE WILL AT LEAST BRING
AN INCREASE IN CLOUDINESS FRIDAY INTO SATURDAY. PRECIPITATION IS
A MUCH DICIER PROPOSITION. THE GEM IS VERY AGGRESSIVE WITH THIS
STRING OF SHORTWAVES AND DOES BRING LIGHT SNOW ACROSS THE AREA
FRIDAY NIGHT AND SATURDAY MORNING. HOWEVER...THE REST OF THE
GUIDANCE DOWNPLAYS THE POTENTIAL FOR LIFT IN THIS AREA AND KEEPS
SNOW FAR TO OUR NORTHEAST.

THE BEST POTENTIAL FOR SNOWFALL IS LIKELY THE LATTER PART OF THE
WEEKEND AS ANOTHER SHORTWAVE TRACKS ANOTHER MODEST CLIPPER TOWARDS
THE AREA. THE GEM IS BY FAR THE MOST AGGRESSIVE WITH A MUCH
STRONGER SHORTWAVE DRIVING A STRONGER SURFACE LOW FARTHER SOUTH
THAN OTHER MODELS. THE GFS IS CONSIDERABLY WEAKER WITH BOTH OF
THESE FEATURES...WHILE THE EURO FALLS SOMEWHAT IN BETWEEN AS A BIT
OF A COMPROMISE. IN ANY CASE...JET STREAKS IN THE UPPER ATMOSPHERE
DO APPEAR TO SET UP MUCH MORE FAVORABLY THAN WITH THE LEAD
SYSTEM...MAKING THE IDEA OF SNOW MORE PALATABLE FOR SUNDAY. THE
GEM SEEMS TOO AGGRESSIVE WITH THESE FEATURES ALOFT...SO THE
FORECAST NOW LEANS TO THE EURO/GFS AND KEEPS POPS RELATIVELY LOW.

FINALLY...EARLY NEXT WEEK WILL BRING A THIRD SHORTWAVE THROUGH THE
UPPER PATTERN AND ONE LAST SHOT AT UNSETTLED WEATHER. AT THIS
RANGE...DETAILS ARE SKETCHY. LIKE PREVIOUS WAVES...THE CANADIAN IS
MUCH MORE AGGRESSIVE...BRINGING A DECENT JET STRUCTURE AND SOME
FRONTOGENESIS TO NORTHEAST WISCONSIN TO HELP PROVIDE THE LIFT FOR
MORE LIGHT SNOW. THE GFS AND EURO ARE MORE PESSIMISTIC...KEEPING
THE BEST JET STRUCTURE LARGELY TO OUR NORTH. ADDITIONALLY...THERE
MAY BE SOME QUESTION ABOUT THE AVAILABLE MOISTURE WITH THE
PROGRESSIVE NATURE OF THESE CLIPPERS RESTRICTING THE DURATION OF
SOUTHWEST WINDS. IT IS WORTH NOTING THAT THE GFS SHOWS SOME LIGHT
SNOW IN THE FAR NORTH...SO EVEN THE MORE PESSIMISTIC MODELS DO
NOT COMPLETELY DISMISS THE IDEA. WILL KEEP SOME SLIGHT CHANCE POPS
IN OUR AREA IN DEFERENCE TO THE CANADIAN...BUT WILL KEEP THE BEST
CHANCE FOR SNOW TO OUR NORTH.

THROUGH ALL THIS...THE PROGRESSIVE PATTERN AND ABSENCE OF A
RENEWED ARCTIC SURGE WILL KEEP TEMPERATURES FROM PLUMMETING
AGAIN...INSTEAD STAYING NEAR NORMAL. INDEED...TEMPERATURES MAY
EVEN START TO BECOME SLIGHTLY ABOVE NORMAL NEXT WEEK.
&&

.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1025 PM CST TUE MAR 3 2015

ARCTIC AIR NOW SURGING BACK INTO THE FCST AREA. STILL SOME
LINGERING LOW CLDS...BUT THOSE SHOULD DECR AS THE COLDER AND DRIER
AIR BECOMES ESTABLISHED ACRS THE AREA. EXPECT GENERALLY GOOD
FLIGHT CONDITIONS...THOUGH SFC WINDS WILL BE A LITTLE GUSTY
TOMORROW.
&&

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

$$

SHORT TERM.....ECKBERG
LONG TERM......LUCHS
AVIATION.......SKOWRONSKI