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000
FXUS63 KGRB 260338
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
938 PM CST SUN JAN 25 2015

UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE
AND NEW INFORMATION ADDED TO UPDATE SECTION

.UPDATE...
ISSUED AT 928 PM CST SUN JAN 25 2015

MAIN CHG TO THE FCST THIS EVENING WAS TO ADJUST PCPN TIMING BASED
ON THE LATEST GUIDANCE. SNOW MAY TAKE A BIT LONGER TO GET STARTED
IN THE E THAN EARLIER EXPECTED. IT ALSO APPEARS THERE COULD BE A
FAIRLY FAVORABLE SET-UP FOR LAKE-EFFECT OVER ERN WI AS THE EVENT
WINDS DOWN MONDAY NIGHT. INSTABILITY WL BE SUFFICIENT WITH 850 MB
TEMPS OF -10C TO -12C. IT ALSO APPEARS A WELL DEFINED SFC TROF WL
LINGER NNWD NEAR THE LAKESHORE...WITH ENHANCED CONVERGENCE BTWN
ELY FLOW OVER THE LAKE AND NLY FLOW A FEW COUNTIES INLAND.

MID-LVL MOISTURE SHIFTG EWD AND WARMER TEMPS STILL SUPPORT A CHC
OF FZDZ OVER C/N-C WI AS THE SNOW DIMINSHES LATER MON AFTN-MON
EVENING. BUT THE FZDZ WOULD BE FALLING ON TOP OF THE SNOW...SO THE
IMPACT IS NOT EXPECTED TO BE NEARLY AS GREAT AS WHEN FZDZ FALLS ON
BARE GROUND/ROADS. SITN DOES NOT SEEM WORTHY OF HEADLINE AT THIS
POINT...BUT MIDNIGHT SHIFT CAN REASSES AND ISSUE ONE IF LATER DATA
LOOK MORE OMINOUS.
&&

.SHORT TERM...TONIGHT AND MONDAY
ISSUED AT 253 PM CST SUN JAN 25 2015

THE LATEST RAP ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW ARCTIC HIGH
PRESSURE BUILDING SOUTHWARD OVER LAKE SUPERIOR EARLY THIS
AFTERNOON.  A FEW POCKETS OF STRATO-CU REMAIN OVER THE FORECAST
AREA...BUT MAJORITY OF LOCATIONS HAVE CLEARED OUT.  WILL SEE A SHORT
PERIOD OF MOSTLY CLEAR SKIES THIS AFTERNOON...THEN AN AREA OF
THINNING ALTO-CUMULUS WILL MOVE SOUTHEAST ACROSS NORTHERN
WISCONSIN.  LOOKING FARTHER UPSTREAM...THE NEXT CLIPPER SYSTEM IS
MOVING SOUTHEAST INTO THE LAKE WINNIPEG REGION...AND POISED TO
ARRIVE LATE TONIGHT INTO MONDAY MORNING.  SNOWFALL POTENTIAL WITH
THIS SYSTEM IS THE MAIN FORECAST CONCERN.

TONIGHT...LINGERING AREAS OF STRATO-CU OVER CENTRAL AND NORTHEAST
WISCONSIN WILL BE FADING BY SUNSET AS INCOMING ARCTIC HIGH AND VERY
DRY AIR OVERWHELM THE LOW LEVEL MOISTURE.  POCKET OF MID-CLOUDS WILL
BE MOVING ACROSS THE FORECAST AREA AT THE START OF THE EVENING BUT
THINKING THESE CLOUDS WILL THIN/DIMINISH AS SUBSIDENCE INCREASES.
IF THIS OCCURS...THIS WILL LEAVE A FEW HOUR WINDOW FOR GOOD
RADIATIONAL COOLING OVER N-C WISCONSIN UNTIL CLOUDS INCREASE AGAIN
LATE IN THE EVENING.  WILL DROP LOW TEMPS ACROSS N-C WISCONSIN AND
THEN SHOW RISING TEMPS AFTER MIDNIGHT.  THE NEXT ALBERTA CLIPPER
WILL MAKE QUICK PROGRESS TONIGHT AND REACH THE BOUNDARY WATERS OF
NORTHERN MINNESOTA BY 12Z MON.  WARM ADVECTION AHEAD OF THE CLIPPER
WILL CAUSE MID AND HIGH CLOUDS TO LOWER OVERNIGHT...WITH A CHANCE OF
SNOW ARRIVING OVER N-C WISCONSIN BETWEEN 09-12Z.  UNCERTAINTY IS
RATHER HIGH WITH LOW TEMPS ACROSS N-C WISCONSIN...BUT WENT BELOW
GUIDANCE WITH LOWS RANGING FROM THE LOWER SINGLE DIGITS ABOVE ZERO
NORTH TO AROUND 10 ABOVE SOUTH.

MONDAY...LOW PRESSURE WILL CONTINUE TO MOVE SOUTHEAST AND WEAKEN AS
IT MOVES INTO NORTHWEST WISCONSIN BY 00Z. DECENT MID-LEVEL FGEN WILL
ACCOMPANY THE WARM ADVECTION OVER CENTRAL WISCONSIN DURING THE
MORNING BUT WILL GRADUALLY WEAKEN AS IT MOVES INTO EASTERN WISCONSIN
IN THE AFTERNOON.  WITH SNOW RATIOS AROUND 15 TO 1...NORTH-CENTRAL
AND CENTRAL WISCONSIN COULD SEE AROUND 2 INCHES OF ACCUMULATION BY
THE END OF THE DAY WHILE EASTERN WISCONSIN SHOULD SEE AROUND AN INCH
OR LESS.  THE SNOW MAY ALSO MIX WITH FREEZING DRIZZLE OVER CENTRAL
WISCONSIN BY LATE IN THE AFTERNOON AS MID-LEVEL MOISTURE BEGINS TO
PEEL OUT.  WILL INCREASE PRECIP CHANCES SUBSTANTIALLY.  HIGHS
RETURNING TO THE 20S AS WINDS SHIFT TO THE SOUTH.

.LONG TERM...MONDAY NIGHT THROUGH SUNDAY
ISSUED AT 253 PM CST SUN JAN 25 2015

NORTHWEST UPPER FLOW WILL CONTINUE THOUGH AT LEAST
THE END OF THIS WEEK. WEAK CLIPPER SYSTEMS WILL MOVE THROUGH
MONDAY NIGHT AND AGAIN WEDNESDAY NIGHT AND THURSDAY AND AGAIN
SATURDAY. THE MIDWEEK CLIPPER SYSTEM PROBABLY HAS THE BEST CHANCE
OF PRODUCING MORE THAN AN INCH OR TWO OF SNOW DEPENDING ON HOW
MUCH PHASING THERE IS WITH SOUTHERN STREAM JET ENERGY PASSING BY
TO THE SOUTH.

THERE IS ALSO LIMITED MOISTURE WITH ALL THREE SYSTEMS SO DO NOT
EXPECT ANY BIG SNOWS THIS WEEK. UPPER HEIGHTS BUILD THROUGH MID
WEEK DESPITE THE FLOW BEING NORTHWEST. THIS SHOULD RESULT IN ABOVE
NORMAL TEMPERATURES. COLDER AIR WILL ARRIVE LATER THIS WEEK WITH
THE POSSIBILITY OF REAL ARCTIC AIR SUNDAY OR MONDAY OF THE
FOLLOWING WEEK.
&&

.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 928 PM CST SUN JAN 25 2015

NO SIG CHCS TO AVN FCST WITH THE 06Z TAFS. PATCH OF MID CLDS WL
CONT TO SHIFT OFF TO THE SE...BUT WL BE REPLACED BY MUCH MORE
EXPANSIVE CLD DECK THAT WL LOWER WITH TIME. SNOW AHEAD OF INCOMING
SYSTEM LOOKS TO START IN THE 14Z-18Z TIME FRAME W AND 16Z-20Z IN
THE E...WITH PERHAPS SOME SHSN OFF LAKE MICHIGAN WORKING WWD INTO
LAKESHORE AREAS EARLIER. EXPECT MAINLY IFR VSBYS WITH THE SNOW
BAND ON MONDAY.
&&

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

$$

UPDATE.........SKOWRONSKI
SHORT TERM.....MPC
LONG TERM......RDM
AVIATION.......SKOWRONSKI