FXUS63 KGRB 100329
AFDGRB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
929 PM CST WED DEC 9 2009
.UPDATE...NO BIG CHANGES MADE TO THE REST OF THE FORECAST FOR
TONIGHT AND WILL LEAVE CURRENT HEADLINES IN TACT. BACK EDGE OF THE
COMMA HEAD AND DEEP MOISTURE IS NOW MOVING ACROSS WESTERN
WISCONSIN WITH WIDESPREAD LIGHT SNOW SHOWERS/FLURRIES CONTINUING
WITHIN IT. TIMING TOOL AND LATEST 00Z NAM INDICATES DEPARTURE OF
THIS DEEPER MOISTURE BETWEEN 09Z AND 12Z...WHICH THE INHERITED
FORECAST HANDLES WELL. WITH THE WINDS AND CLOUD
COVER...TEMPERATURES ARE A COUPLE DEGREES WARMER THAN THE PREVIOUS
FORECAST OVER CENTRAL WISCONSIN. STILL THOUGH...ZERO DEGREE
TEMPERATURES HAVE MOVED INTO EASTERN MINNESOTA...AND THAT AIRMASS
SHOULD REACH CENTRAL WISCONSIN BY 12Z. THATS CLOSE ENOUGH FOR ME
TO KEEP THE CURRENT WIND CHILL ADVISORY AS IS. THOUGH DO THINK IT
WILL BE TOUGH FOR EASTERN SHAWANO...OUTAGAMIE...AND WINNEBAGO
COUNTIES TO REACH -20 DEGREE WIND CHILLS BY MORNING. PROBABLY -15F
WIND CHILLS WILL BE MORE LIKE IT...BUT WONT SPLIT HAIRS OVER THIS
AS THIS DIFFERENCE WILL BE HARDLY PERCEPTIBLE.
FARTHER NORTH ACROSS VILAS...OBSERVATIONS AT IRONWOOD HAVE SHOWN
SUSTAINED VSBYS BETWEEN 3/4-1 1/2SM THIS EVENING. LNL AND ARV
VSBYS HAVE BOUNCED AROUND A LITTLE MORE. MADE A CALL TO LOCAL LAW
ENFORCEMENT WHICH INDICATED ANOTHER INCH OR TWO OF SNOW HAS FALLEN
SINCE 6PM. WILL LET THE WARNING PROCEED AS PLANNED UNTIL 06Z.
AFTER 06Z...850MB TEMPERATURES FALL COLDER THAN THE DENDRITIC
GROWTH ZONE AND WINDS WILL BACK AROUND MORE TOWARDS THE WNW. BOTH
VARIABLES WILL CAUSE A DECREASE IN SNOW ACCUMULATIONS OVER VILAS.
WILL MAKE A LAST MINUTE CALL CLOSER TO MIDNIGHT AS TO WHETHER TO
LET THE HEADLINE EXPIRE OR POSSIBLY EXTEND IT.
UPDATED ZONES OUT SHORTLY.
MPC
&&
.PREV DISCUSSION...ISSUED AT 801 PM CST WED DEC 9 2009...
UPDATE...SNOWFALL INTENSITIES HAVE IMPROVED THIS EVENING ALONG
THE LAKE MICHIGAN SHORELINE. MOST VISIBILITIES HAVE RISEN TO
GREATER THAN 2 MILES...ALTHOUGH BRIEF POCKETS OF MODERATE SNOW
SHOWERS MAY REDUCE VISIBILITIES TO 1 MILE TEMPORARILY. LITTLE TO NO
ADDITIONAL ACCUMULATION IS EXPECTED SO WILL CANCEL THE SNOW AND
BLOWING SNOW ADVISORY. WINDS WILL STILL BE GUSTY FOR THE REST OF
THE NIGHT WITH GUSTS TO 30 MPH STILL POSSIBLE THROUGH 12Z
THU...AND SOME MINOR BLOWING AND DRIFTING SNOW WILL OCCUR.
WILL TAKE A LOOK AT THE HEADLINES LINGERING ACROSS VILAS COUNTY AND
THE WIND CHILL ADVISORY OVER THE NEXT HOUR.
MPC
DISCUSSION ISSUED AT 308 PM CST WED DEC 9 2009...
SHORT TERM...TONIGHT AND THURSDAY. THE AFFECTS OF INTENSE WINTER
STORM CONTINUE TO DIMINISH FAIRLY QUICKLY THIS AFTERNOON AS THE
SYSTEM LIFTS NORTHEAST OF LOWER MICHIGAN. LATEST OBSERVATIONS
SUPPORT ENDING THE BLIZZARD HEADLINE AND WINTER STORM WARNING AT
ROUTINE ZONE ISSUANCE THIS AFTERNOON. HAVE BEEN MONITORING VSBYS
ACROSS THE REGION THIS AFTERNOON AND LOWEST VSBYS REMAIN OVER THE
OPEN AREAS OF SRN MN AND IOWA THIS AFTERNOON WHERE THE BEST
SURFACE PRESSURE CHANGE COUPLET EXTENDS FROM EASTERN IA TO UPPER
MICHIGAN. OTHERWISE CRITERIA FOR A BLOWING SNOW HEADLINE OF 1/2
MILE VSBYS ALSO NOT BEING MET AS WELL SO WILL JUST END ALL
HEADLINES...WITH THE EXCEPTION OF LES ACTIVITY OVER VILAS COUNTY.
FOR LAKE SHORE COUNTIES WILL LOWER HEADLINE TO SNOW AND BLOWING
SNOW DUE TO LINGERING SNOW AS PER RADAR AND POTENTIAL WIND GUSTS.
EVENING SHIFT MAY WANT TO END EARLIER THAN THE MIDNIGHT ENDING AT
THIS TIME. FOR THE REST OF THE AREA WILL HANDLE WITH AN SPS FOR
THE EVENING RUSH HOUR.
FOR LATER TONIGHT INTO THURSDAY...ATTENTION TURNS TO COLD SURGE OF
AIR. WILL ISSUE A WC ADVISORY FOR PARTS OF CENTRAL AND EAST
CENTRAL WI DUE TO COMBO OF HIGHER WIND SPEEDS IN THE OPEN AREAS AND
TEMPS FALLING TO NEAR ZERO. IT WILL BE CLOSE BUT BEING THE FIRST
WIND CHILL EVENT OR NEAR EVENT OF THE SEASON WILL ISSUE IT.
TEMPS WILL NOT RESPOND MUCH ON THURSDAY DUE TO ONGOING CAA. CLOUDS
ASSOCIATED WITH LARGE DEFORMATION AREA MAY BE SLOW TO DEPART LATE
TONIGHT INTO THURSDAY AND IN ADDITION MID RH IS ALREADY INCREASING
IN THE AFTERNOON IN THE FAST WEST FLOW. USUALLY MODELS OVERDUE
CLOUD COVERAGE IN CAA PATTERNS...BUT NOT SURE THIS IS THE CASE
THIS TIME.
LONG TERM...THURSDAY NIGHT THROUGH FRIDAY
A WEAK DISTURBANCE WILL MOVE SOUTHEAST INTO THE AREA THURSDAY
NIGHT INTO FRIDAY MORNING. THIS SYSTEM MAY BRING A FEW FLURRIES
AS IT PASS THROUGH THE AREA. DID ADD FLURRIES TO THE FORECAST
FOR THURSDAY NIGHT AND FRIDAY.
ATTENTION TURNS TO LATER IN THE WEEKEND AS MODELS HAVE SIGNIFICANT
DIFFERENCES IN SOLUTIONS FOR SUNDAY NIGHT AND MONDAY. THE ECMWF IS
MORE AGGRESSIVE WITH THE SYSTEM AND WOULD BRING AN ACCUMULATING
SNOWFALL TO THE REGION SUNDAY NIGHT AND MONDAY. THE 00Z CANADIAN
MODEL RUN LAST NIGHT HAD A WEAK FEATURE DURING THIS TIME PERIOD...
BUT HAS BACKED OFF ON THE 12Z RUN THIS MORNING. THE GFS HAS A WEAKER
SYSTEM...BUT PUSHES IT THROUGH THE REGION SATURDAY NIGHT INTO SUNDAY
MORNING. WITH SUCH DIFFERENCES...WILL CONTINUE WITH THE CURRENT FORECAST
UNTIL MODELS CONVERGE ON A SOLUTION.
BELOW NORMAL TEMPERATURES WILL CONTINUE INTO THE WEEKEND.
TEMPERATURES SHOULD MODERATE SOME EARLY NEXT WEEK BEFORE THE
NEXT INTRUSION OF ARCTIC AIR MOVES INTO THE CENTRAL UNITED STATES
BY THE MIDDLE OF NEXT WEEK. MODELS DIFFERENCES NOTED BETWEEN THE
GFS AND ECMWF. PLENTY OF TIME TO SORT OUT THE DETAILS.
AVIATION...MVFR CIGS AND VSBYS WILL LINGER THIS EVENING OVER
MOST LOCATIONS AND WILL IMPROVE TO MAINLY VFR CONDITIONS LATE
TONIGHT INTO THURSDAY.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
WIND CHILL ADVISORY FROM 3 AM TO 10 AM CST THURSDAY FOR WIZ030-
031-035>038-045-048-049.
WINTER STORM WARNING UNTIL MIDNIGHT CST TONIGHT FOR WIZ005.
&&
$$
