FXUS63 KDLH 240622
AFDDLH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
1222 AM CST THU DEC 24 2009
.AVIATION.../06Z TAF ISSUANCE/
SNOW HAS MOVED INTO NW WI...AND MUCH OF CTR MN AS OF 6Z. CIGS AND
VSBYS QUICKLY DROP TO THE IFR AND LIFR RANGE FROM SOUTH TO NORTH...AS
MAJOR WINTER STORM BEGINS TO AFFECT THE REGION. THE SNOW WILL BE
HEAVIEST IN THE EARLY MORNING HOURS...WITH A BREAK LATE THUR
MORNING INTO THE AFTERNOON...BEFORE ANOTHER ROUND OF HEAVIER SNOW
MOVES INTO NE MN AND NW WI AROUND 00Z FRI. WINDS WILL BE NORTHEAST
AND GUSTY...ESP AT KDLH WHERE BLSN IS LIKELY THROUGH MUCH OF THE
TAF PD.
LONKA
&&
.PREV DISCUSSION... /ISSUED 858 PM CST WED DEC 23 2009/
UPDATE...
DECREASED POPS THIS EVENING, SMOOTHED SNOW DISTRIBUTION, AND GAVE
SNOW TO EVERYONE LATE TONIGHT. INCREASED WINDS ALONG THE LAKE
SHORE. RAISED TEMPERATURES A LITTLE FOR THE NEXT FEW PERIODS.
DISCUSSION...
THE FINE-RESOLUTION GRID MODELS HAVE BEEN VERY CONSISTANT
AND...AS IT TURNS OUT CORRECT ABOUT SNOW DISTRIBUTION AS THIS
STORM APPROACHES. THE NAM...LAMP...AND RUC ALL BRING ACCUMULATING
SNOW TO THE EDGE OF OUR FORECAST AREA AT 06Z TONIGHT...TO DULUTH
AT 09Z AND SPREAD IT FITFULLY NORTHWARD AT 12Z WITH EVERYBODY
GETTING IT AT 15Z. IMPROBABLY HIGH WINDS...ESPECIALLY ON GRID
MODELS...ARE TURNING OUT TO BE STILL TOO LOW AROUND THE BIG
LAKE...GALE FORCE GUSTS HAVE ALREADY BEEN SHOWING UP ON THE BUOYS
AND AROUND DOWNTOWN DULUTH FOR A WHILE. THAT BLIZZARD WARNING IS
LOOKING LIKE A NO-BRAINER...WE HOPE WE AREN/T FORCED TO SPREAD IT
EVEN FURTHER LATER ON. THE MODELS HAVE BEEN UP AND DOWN WITH
PRECIP AMOUNTS...THERE ARE A NUMBER OF FACTERS. THERE IS NO DEEP
ORGANIZED DYNAMIC FORCING...BUT PLENTY OF STRONG OROGRAPHICS ALONG
THE COASTLINE...THE NAM LOOKS REAL CONVINCING HERE. THE COLUMN IS
QUITE WARM AT MID AND HIGH LEVELS FOR THIS TIME OF YEAR...AND THE
WHOLE PATTERN HAS FALL/SPRING OVERTONES RATHER THAN WINTER.
THUS...THE COLUMN WILL BE ABLE TO HOLD QUITE A BIT OF DEEP
TROPICAL MOISTURE THAT IS FLOODING IN FROM THE CARIBBEAN
SEA...THROUGH THE WESTERN GULF...AND UP TOWARD OUR AREA. WE ARE
FINDING OURSELVES IMPRESSED WITH THE MORE EXTREME-LOOKING NAM
DURING THE NEXT 48 HOURS...THEIR MODELING OF THE OROGRAPHICS
AROUND THE LAKE LOOK GOOD. RIGHT NOW...ALL THE MODELS ARE BACK TO
SLOWLY INCREASING PRECIPITATION AMOUNTS. COLUMN STRETCHING AND
THE SHEER MASS OF SNOW FALLING INTO THE LOWER PARTS OF THE COLUMN
AND MECHANICAL UPGLIDE OF PARCELS ARE APT TO KEEP IT MOSTLY OR ALL
SNOW EVEN OVER MOST OF NORTHWEST WI...EVEN WITH STRONG WARM AND
MOISTURE ADVECTION CONTINUING.
PREV DISCUSSION... /ISSUED 237 PM CST WED DEC 23 2009/
SHORT TERM...TONIGHT THROUGH SATURDAY...
THINGS ARE STARTING TO EVOLVE A BIT MORE RAPIDLY THIS AFTERNOON AS
DEEP UPPER TROF OVER THE WRN EMERGES ONTO THE PLAINS WITH SFC LOW
DEVELOPMENT NOW UNDERWAY ACROSS TEXAS. LEAD S/W TROF ASSOCIATED
WITH STRONG WARM ADVECTION AND 40-50 KT LLJ AS WELL AS AN
EXPANDING PRECIP SHIELD PER KMPX/KARX/KDMX RADARS TO OUR SOUTH IS
PROGRESSING STEADILY NORTHWARD..ALONG WITH SOME FREEZING DRIZZLE
ALONG THE NRN PERIPHERY OF THE PRECIP SHIELD. SNOW SHUD EXPAND NWD
INTO THE SRN CWA THIS EVENING AND THEN ACROSS THE REMAINDER OF NRN
MN/NW WI LATE TONIGHT AND TOMORROW MORNING. SNOWFALL AMOUNTS FROM
3 TO 6 INCHES ARE EXPECTED WITH THE LEAD S/W TROF.
DURING THE DAY TOMORROW..UPPER DISTURBANCE DIVING SEWD FROM
MONTANA WILL PHASE IN WITH PRIMARY PV LOBE TRANSLATING EASTWARD
ACROSS THE SRN ROCKIES..RESULTING IN STRONG SFC LOW DEVELOPMENT IN
THE MID MS VALLEY AREA. THIS LOW WILL THEN LIFT NWD INTO IOWA/SRN
MN WHILE STRENGTHENING AND RESULTING IN THE PRIMARY LOBE OF STRONG
LIFT AND HEAVY SNOWFALL RATES LIFTING NWD INTO NRN MN/NW WI
TOMORROW AFTERNOON INTO MIDDAY CHRISTMAS. THERE MAY BE A 3-6 HOUR
BREAK SOMETIME DURING THE DAY TOMORROW..BEFORE PRIMARY LOBE OF
STRONG FORCING FOR UVM MOVES NORTHWARD. THE PEAK OF THE STORM IS
EXPECTED TO BE FROM LATE THRUSDAY AFTERNOON THRU ABOUT MIDDAY OR
SOMETIME DURING THE AFTERNOON ON CHRISTMAS.
LATEST SFC ANALYSIS SHOWS UPPER 40S DEWPOINT ALREADY AS FAR NORTH
AS STL..AND UPPER 60S DEWPOINTS ON SHORE IN THE GULF COAST REGION.
THUS..THIS STORM WILL HAVE COPIOUS AMOUNTS OF MOISTURE TO WORK
WITH.. AND 1-2 INCH/HOUR SNOWFALL RATES WILL BE COMMON DURING THE
PEAK OF THE STORM. IN ADDITION..VERY STRONG SFC PRESSURE GRADIENT
WILL COMBINE WITH UNSTABLE CONDITIONS OVER THE LAKE AND REDUCED
FRICTION TO PRODUCE 20-40 MPH WINDS WITH HIGHER GUSTS IN AREAS
ADJACENT TO LK SUPERIOR. WE HAVE UPGRADED SRN LAKE.. SRN ST
LOUIS.. CARLTON AND DOUGLAS COUNTIES TO A BLIZZARD WARNING FOR
THIS REASON. RATHER THAN HAVE A WINTER STORM WARNING AND BLIZZARD
WARNING IN EFFECT FOR THE SAME LOCATION AT DIFFERENT TIMES..WE
OPTED TO KEEP IT SIMPLE AND JUST UPGRADE THE ENTIRE TIME PERIOD.
STORM TOTALS COULD EASILY TOP 20 INCHES ALONG AND JUST WEST OF THE
I35 CORRIDOR. WE STILL ARE PERHAPS A BIT CONSERVATIVE ON THE
SNOWFALL AMOUNTS.
LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY...
MODELS IN GENERAL AGREEMENT IN THE LONG TERM WITH DEPARTURE OF
MAJOR WINTER STORM. WE STILL ANTICIPATE SOME LINGERING LIGHT SNOW
BUT WITH LOW QPF/SNOW AMOUNTS ON SATURDAY. LINGERING SFC TROF
EXPECTED TO REMAIN OVER WESTERN LAKE SUPERIOR UNTIL 29/00Z
TUESDAY. WILL HAVE MENTION OF LES SHOWERS UNTIL THEN. SFC HIGH
INFLUENCES THE FA INTO WEDNESDAY.
&&
.POINT TEMPS/POPS...
DLH 26 23 28 17 / 100 100 100 90
INL 24 20 25 14 / 100 100 100 90
BRD 27 24 28 16 / 100 100 100 90
HYR 31 28 32 17 / 100 100 100 70
ASX 31 28 31 19 / 100 100 100 70
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...WINTER STORM WARNING UNTIL 6 AM CST SATURDAY FOR MNZ033-034-036-
038.
WINTER STORM WARNING FROM 6 AM THIS MORNING TO 6 AM CST SATURDAY
FOR MNZ010>012-018-019-021-025-026-035.
BLIZZARD WARNING FROM 6 AM THIS MORNING TO 6 AM CST SATURDAY FOR
MNZ020-037.
WI...WINTER STORM WARNING UNTIL 6 AM CST SATURDAY FOR WIZ006-007.
WINTER STORM WARNING FROM 6 AM THIS MORNING TO 6 AM CST SATURDAY
FOR WIZ002>004-008-009.
BLIZZARD WARNING FROM 6 AM THIS MORNING TO 6 AM CST SATURDAY FOR
WIZ001.
LS...SMALL CRAFT ADVISORY UNTIL 6 PM CST THIS EVENING FOR LSZ121-
140>148.
GALE WARNING FROM 6 PM THIS EVENING TO 6 PM CST FRIDAY FOR
LSZ121-140>148.
&&
$$
