FXUS63 KDLH 101016 AAA
AFDDLH
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE DULUTH MN
416 AM CST THU DEC 10 2009
.SHORT TERM...TODAY THROUGH FRIDAY NIGHT...
MAJOR WINTER STORM HAS EXITED THE GREAT LAKES REGION EARLY THIS
MORNING..AND IS SLOWLY LOSING ITS LINGERING EFFECTS ON THE WRN
LAKES AREA. SFC PRESSURE GRADIENT IS SLOWLY RELAXING..WITH MAIN
EFFECT ON WINDS NOW CONFINED TO THE OPEN WATERS OF WRN LK SUPERIOR
WHERE SPEEDS ARE STILL SUSTAINED AT 20-25 KTS. THERE ARE FOUR PRIMARY
CONCERNS IN THE SHORT TERM: 1) DIMINISHING LAKE EFFECT SNOW
SHOWERS ACROSS ASHLAND/IRON COUNTIES THIS MORNING 2) WIND CHILLS
THIS MORNING 3) REDEVELOPMENT AND ORGANIZATION OF WSW/ENE ORIENTED
LAKE EFFECT SNOW BAND TONIGHT FROM OFFSHORE OF DULUTH TO THE TIP
OF THE BAYFIELD PENINSULA AND 4) WIND CHILLS TONIGHT AND FRIDAY MORNING.
KDLH RADAR IS STIL REVEALING CONVECTIVE ECHO TOPS TO 9 KFT THIS
MORNING EAST OF THE APOSTLE ISLANDS..AND THERE IS STILL A RATHER
STRONG LOW LEVEL MASS CONVERGENCE SIGNAL EVIDENT AROUND SAXON
HARBOR. HOWEVER..ALL AVAILABLE SHORT RANGE GUIDANCE INDICATES THAT
WINDS WILL CONTINUE TO BACK WITH TIME THIS MORNING TO A MORE WRLY
DIRECTION. THIS SHUD ACT TO FINALLY SHUT DOWN THE LK EFFECT
MACHINE OVER THE GOGEBIC RANGE. ANOTHER 1 TO MAYBE 3 INCHES IS
POSSIBLE THIS MORNING..BUT CONSIDERING WHAT THEY HAVE EXPERIENCED
IN THE PAST 36 HOURS..THIS IS REALLY NOTHING. THEREFORE..WE HAVE
OPTED TO DISCONTINUE THE WINTER STORM WARNING.
WIND CHILL VALUES ARE MARGINAL THIS MORNING..WITH MOST READINGS
CURRENTLY IN THE -20 TO -25 RANGE..JUST ABOVE ADV THRESHOLDS.
HOWEVER..WE STILL HAVE A FEW HOURS OF COOLING TO GO..AND WINDS
SHUD STAY IN THE 5-10 MPH RANGE. THUS..SEEING AS HOW THIS IS THE
COLDEST MORNING OF THE YEAR THUS FAR..WE/LL LET THE ADVISORY RIDE
THRU 10 AM FOR THE AREAS ACROSS MN WHERE IT IS IN EFFECT. WIND
CHILL VALUES ALSO APPEAR TO BE A CONCERN TONIGHT..WITH W/SW WINDS
FROM 5-10 MPH AND SIMILAR TEMPS..IF NOT A FEW DEGREES COLDER IN
SOME LOCALES. HOWEVER..WIND CHILLS WILL BE RIGHT NEAR THRESHOLD
VALUES..AND INSTEAD OF ISSUING A NEW ADVISORY FOR TONIGHT AT THIS
TIME FOR A LOWER CONFIDENCE EVENT AND HAVING TWO ADVISORIES
OUT..WE WILL ALLOW THE DAY SHIFT TO EVALUATE FURTHER ON THE NEED
FOR A WIND CHILL ADVISORY TONIGHT/FRIDAY MORNING.
FINALLY..ALMOST ALL AVAILABLE SHORT RANGE MODEL GUIDANCE BACKS
WINDS TO A 250-260 DIRECTION OVER MUCH OF THE AREA AND WRN LK
SUPERIOR BY LATE THIS AFTERNOON. SUCH A CHANGE IN LOW LEVEL FLOW
TRAJECTORIES WILL BASICALLY DOUBLE THE FETCH LENGTH FOR THE TIP OF
THE BAYFIELD PENINSULA /TWO HARBORS TO THE APOSTLES VERSUS DULUTH
TO THE APOSTLES/. WITHIN ABOUT 3-6 HOURS OF THIS FETCH CHANGE..
MOST GUIDANCE IS INSISTENT THAT A NEW LK EFFECT SNOW BAND WILL
DEVELOP ORGANIZE FROM OFFSHORE OF DULUTH..ACROSS THE NRN BAYFIELD
PENINSULA AND EWD TO HOUGHTON MICHIGAN..WITH THIS BAND PERSISTING
IN SOME FORM RIGHT ON INTO SATURDAY. OBVIOUSLY..A SMALL ERROR IN
WIND DIRECTION /SUCH AS THE ENE WIND DIRECTION ERROR IN THE DULUTH
AREA ON TUE NIGHT/ CAN HAVE VERY LARGE IMPACT ON SNOW AMOUNTS. BUT
GIVEN THAT THE MASS FIELDS SUPPORT THIS IDEA..OUR CONFIDENCE IN
HOISTING A NEW LK EFFECT SNOW ADVISORY FOR NRN BAYFIELD COUNTY IS
HIGH ENUF. THE BAND SHUD BECOME BEST ORGANIZED TONIGHT AND FRI
MORNING..SO WE OPTED TO START THE ADVISORY AT 6 PM THIS EVENING.
&&
.LONG TERM...SATURDAY THROUGH WEDNESDAY...
MODELS ARE IN GENERAL AGREEMENT THAT A BRIEF PERIOD OF WARM AIR
ADVECTION WILL OCCUR SAT/SUN IN RESPONSE TO TEMPORARY BACKING OF
MID LVL FLOW. LOW CONFIDENCE ON PLACEMENT/TIMING OF SNOW FLURRIES
OR LIGHT SNOW AS MDLS DIFFER ON SATURATION OF LOW LEVELS. MDLS
DEPICT A SFC BDRY PUSHING NORTH INTO CWA SATURDAY. LATEST GUIDANCE
EC/GFS SUGGESTS SIGNIFICANT WARMUP...MORE SO THAN IN EXISTING
FCST. GIVEN TIME OF YEAR...TENACITY OF SHALLOW ARCTIC AIR...AND
MDL BIASES WITH COLD AIR MASSES...WILL NOT JUMP ON BIG WARMING
YET. AS BOUNDARY ROTATES ACROSS CWA SUNDAY...IT APPEARS ENOUGH
CONVERGENCE IN BOUNDARYLAYER OCCURS TO WARRANT INCREASE IN POPS AT
THAT TIME. THIS SNOW WILL INCREASE SUN NIGHT/MONDAY WITH MODELS
CONVERGING ON INCREASING LIFT/QPF AT THAT TIME. HAVE INCREASED
POPS BUT MAY NEED MORE WITH NEXT UPDATE. MONDAY WILL FEATURE YET
ANOTHER PUSH OF COLD AIR. MAY SEE SOME REDEVELOPMENT OF LES MONDAY
NIGHT/TUESDAY ALONG WISC SNOWBELT.
&&
.AVIATION...
IFR CIGS AT HIB WHERE SOME -SN MAY LINGER UNTIL 12Z. OTHERWISE...
MVFR CONDITIONS AT HYR THROUGH 06Z/11. REMAINDER OF TERMINALS
SHOULD MAINTAIN VFR THROUGH PERIOD.
&&
.POINT TEMPS/POPS...
DLH 2 -5 6 -4 / 10 10 10 30
INL 1 -12 1 -15 / 10 10 10 30
BRD 3 -6 9 -3 / 10 10 10 20
HYR 3 -8 6 -10 / 10 10 10 20
ASX 6 -5 6 -5 / 20 10 10 30
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...WIND CHILL ADVISORY UNTIL 10 AM CST THIS MORNING FOR MNZ010>012-
018>021-025-026-033>037.
WI...LAKE EFFECT SNOW ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST
FRIDAY FOR WIZ002.
LS...SMALL CRAFT ADVISORY UNTIL MIDNIGHT CST FRIDAY NIGHT FOR LSZ121-
146>148.
&&
$$
MILLER/CANNON
