FXUS63 KAPX 031131
AFDAPX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
631 AM EST THU DEC 3 2009
.SYNOPSIS.../ISSUED AT 423 AM/
A STORM SYSTEM THAT ORIGINATED OVER THE GULF TUESDAY...WILL LIFT
NORTH ALONG THE ATLANTIC COAST TONIGHT AND THURSDAY...BEFORE
ROTATING BACK INTO QUEBEC FRIDAY.
SNOW SHOWERS WILL BECOME DOMINATE OVER THE NORTHERN GREAT LAKES...
THURSDAY THROUGH THE WEEKEND...IN RESPONSE TO COLDER AIR FILTERING
INTO THE STATE...ON THE BACK SIDE OF THE ATLANTIC STORM SYSTEM.
ADAM
&&
.SHORT TERM.../ISSUED AT 423 AM/...TODAY
THINGS WORKING OUT PRETTY MUCH AS ANTICIPATED AS DEFORMATION/TROWEL
DRIVEN LIGHT PRECIPITATION SHIELD HAS OVERSPREAD MUCH OF NORTHERN
LOWER MICHIGAN EARLY THIS MORNING AS PARENT MID LEVEL WAVE AND
SURFACE LOW PASS OFF TO OUR SOUTHEAST. HOWEVER...CAA HAS BEEN
SOMEWHAT DELAYED... RESULTING IN RAIN HANGING ON LONGER THAN
ANTICIPATED OVER OUR SOUTHEAST COUNTIES...CUTTING FURTHER INTO
ALREADY FORECAST LIGHT SNOW ACCUMULATIONS. MAIN SHOW FOR THE NEXT
SEVERAL DAYS IS DEEP TROUGH AXIS...AND ACCOMPANYING COLD POOL
(NEGATIVE LOW TO MID TEENS AT 850MB PER REGIONAL SOUNDING ANALYSIS)
...DIGGING INTO THE WESTERN LAKES THIS MORNING. THIS WILL QUICKLY
SET THE STAGE FOR OUR FIRST SIGNIFICANT LAKE EFFECT SNOW EVENT OF
THIS WINTER SEASON (OH...ONLY ABOUT 2 WEEKS LATE). FORECAST CONCERNS
CENTER ON SUCH...SPECIFICALLY TEMPORAL AND SPATIAL RESOLUTION OF
LAKE INDUCED SNOWS THROUGH THIS WEEKEND...AND SUBSEQUENT HEADLINE
POSSIBILITIES.
TODAY...IN TYPICAL NORTHERN MICHIGAN WINTER-TIME TRADITION...KINDA
THE CALM BEFORE THE STORM AS CURRENT STORM EXITS THIS MORNING.
LINGERING SYNOPTIC DRIVEN SNOW SHIELD (SHOULD BE ALL SNOW BY
MORNING...PERHAPS A MIXTURE FAR SOUTHEAST) WILL CONTINUE TO PULL OFF
TO THE EAST THIS MORNING...WITH ANY ADDITIONAL LIGHT ACCUMULATIONS
REMAINING UNDER AN INCH. LAKE MORPHOLOGY A LITTLE HARDER TO
DISCERN...ESPECIALLY EARLY THIS MORNING...AS OUR RADAR HAS BEEN OUT
OF COMMISSION SINCE YESTERDAY (TECHS WORKING ON THE ISSUE NOW).
BASED OF MQT RADAR SHOWING LIGHT ACTIVITY ALREADY COMING OFF LAKE
SUPERIOR AND RUC ANALYSIS SHOWING NORTHERN LAKE MICHIGAN 850MB
TEMPERATURES DROPPING INTO THE UPPER SINGLE DIGITS BELOW ZERO BY
12Z...WOULD EXPECT AT LEAST SOME LAKE CONVECTION TO FIRE EARLY THIS
MORNING...TARGETING FAVORED NORTH FLOW AREAS NEAR GRAND TRAVERSE BAY
AND POINTS SOUTHWEST. WINDS STEADILY BACK THROUGH THE DAY...
EVENTUALLY BECOMING MORE NORTHWEST THIS AFTERNOON. THIS WILL TARGET
THE TRADITIONAL SNOWBELTS OF NORTHWEST CHIPPEWA COUNTY AND NORTHWEST
LOWER MICHIGAN. DESPITE INCREASINGLY INSTABILITY AS DELTA T/S PUSH
THE UPPER TEENS...STEADILY BACKING WIND FIELD...INITIAL LOW
INVERSION HEIGHTS (SUB 850MB) AND TYPICAL DIURNAL DISRUPTION
(ESPECIALLY GIVEN LACK OF SNOW COVER) SHOULD KEEP SNOW AMOUNTS IN
CHECK TODAY...WITH AMOUNTS AT AN INCH OR LESS. FOR THE REMAINDER OF
THE AREA...SHORTWAVE EJECTING OUT OF THE WESTERN LAKES TROUGH AXIS
ARGUES FOR KEEPING AFTERNOON SNOW SHOWER THREAT ACROSS ALL BUT
EXTREME SOUTHEAST ZONES. TEMPERATURES WILL FALL THROUGHOUT THE
DAY...WITH LATE AFTERNOON READINGS IN THE UPPER 20S TO LOWER
30S...WITH MID 30S REMAINING ACROSS SOUTHEAST ZONES.
MSB
&&
.LONG TERM.../ISSUED AT 423 AM/...TONIGHT AND BEYOND
TONIGHT AND FRIDAY...LAKE INDUCED SNOWS TAKE CENTER STAGE THROUGH
THIS PERIOD IN MAINTENANCE OF VERY GOOD OVER-WATER INSTABILITY
REGIME...WITH INCREASING INVERSION LEVELS AND DEEP MOISTURE ROTATING
BACK ACROSS THE LAKES. NAM-WRF BUFKIT ANALYSIS SHOWS EXCELLENT
PARAMETERS FOR LAKE CONVECTION DEVELOPING QUICKLY TONIGHT...
ESPECIALLY ACROSS NORTHERN LAKE MICHIGAN...AS NEXT SHORTWAVE ROTATES
THROUGH...SPIKING EQUILIBRIUM LEVELS TO NEAR 16KFT AND LAKE INDUCED
CAPE PROFILES NEAR 700 J/KG. INITIALLY SOMEWHAT LESS IMPRESSIVE OVER
EASTERN UPPER MICHIGAN AS BEST MID LEVEL DYNAMICS PASS JUST TO THE
SOUTH TONIGHT...BUT STILL APPRECIABLE AS INVERSION LEVELS STEADILY
INCREASE THROUGH THE NIGHT.
OFF LAKE SUPERIOR...LOW LEVEL CONVERGENCE AXIS FOCUSES INTO ALGER
AND LUCE COUNTY THIS EVENING...EVENTUALLY PIVOTING INTO NORTHWEST
CHIPPEWA COUNTY DURING THE EARLY MORNING HOURS. STILL SOME CONCERN
LIGHT WIND FIELDS MAY LEAD TO DRAINAGE FLOW OFF THE ONTARIO PLATEAU
NORTH OF THE SOO...KEEPING FOCUS WEST OF THE FORECAST AREA. IF BANDS
DO PIVOT INTO THE AREA DURING THE EARLY MORNING...WOULD EXPECT 2 TO
3 INCHES NEAR THE POINT...WITH ONLY THE DELAYED TIMING KEEPING
AMOUNTS SUB-ADVISORY. WINDS CONTINUE TO BACK TO MORE WEST SOUTHWEST
FRIDAY AFTERNOON...DRIVEN THE SNOW BANDS INTO ONTARIO. BEFORE THIS
OCCURS...WOULD EXPECT ANOTHER 2 INCHES OR SO DURING THE
MORNING.
OFF LAKE MICHIGAN...MUCH MORE COMPLEX AS ONGOING AFTERNOON LES
QUICKLY INTENSIFIES THIS EVENING. USING STREAMLINE BOUNDARY LAYER
WIND ANALYSIS AND DIVERGENCE FIELDS...APPEARS HEAVIEST SNOWS WILL
PUSH INTO LEELANAU...BENZIE...AND GRAND TRAVERSE COUNTY THIS
EVENING...PUSHING STEADILY INLAND OVERNIGHT. WHILE BACKING WINDS
SHOULD PREVENT GOOD BANDING STRUCTURES...EXPECTED VIGOROUS
CONVECTION AND LONGEVITY OF SNOWS (SHOULD LAST THROUGH AT LEAST
FRIDAY MORNING) JUSTIFIES ISSUANCE OF FIRST WINTER WEATHER ADVISORY
OF THE SEASON FOR SAID COUNTIES...INCLUDING ANTRIM AND KALKASKA.
COULD SEE AMOUNTS APPROACH A HALF A FOOT BY MIDDAY FRIDAY IN THESE
AREAS. CONVERGENCE SIGNATURE WEAKENS LATER TONIGHT AND FRIDAY AS
SNOWS ADVANCE INLAND...SOMEWHAT LIMITING THE ACCUMULATION POTENTIAL.
BY LATER FRIDAY...WINDS GO WSW...TARGETING THE TIP OF THE MITT
COUNTIES FOR THE HEAVIEST SNOWS...ALTHOUGH DIURNAL DISRUPTION SHOULD
PREVENT SIGNIFICANT ACCUMULATIONS.
AWAY FROM THE TRADITIONAL LAKE ZONES...GOOD MOISTURE AND STEEP LOW
LEVEL LAPSE RATES SHOULD ALLOW FOR GOOD SNOW SHOWER COVERAGE
FRIDAY.
FRIDAY NIGHT AND BEYOND...WSW TO SW FLOW LOCKS IN FRIDAY NIGHT
THROUGH AT LEAST SATURDAY...KEEPING THE TIP OF THE MITT AND PARTS OF
SOUTH-EASTERN UPPER MICHIGAN UNDER THE GUN. PARAMETERS REMAIN
STEAD-FAST...WITH HIGH INVERSION LEVELS...ABUNDANT MOISTURE...AND
GOOD OVER-WATER INSTABILITY. COUPLE THIS WITH EXCELLENT FETCH LENGTH
IN SUCH A FLOW...AND HEAVY ACCUMULATIONS CONTINUE TO LOOK LIKELY FOR
THIS AREA. THOUGHT HARD ABOUT ISSUING A WATCH...BUT GIVEN COMPLEXITY
OF INITIAL EVENT TONIGHT AND FRIDAY...WILL DEFER THAT DECISION TO
LATER SHIFTS. OTHERWISE...LIGHTER LAKE SNOWS SHOULD CONTINUE TO
TARGET AREAS ALONG AND WEST OF THE US-131 CORRIDOR. INHERITED GRIDS
ALREADY HAD ALL OF THIS WELL HANDLED...WITH ONLY CHANGE TO BUMP SNOW
AMOUNTS UP SOME IN TIP OF MITT COUNTIES. COOL CONDITIONS AND CHANCES
FOR ADDITIONAL SNOW CONTINUE INTO THE START OF THE NEXT WORK WEEK.
MSB
&&
.MARINE.../ISSUED AT 423 AM/
SCA/S WILL CONTINUE ALL NEARSHORE WATERS AS GUSTY NORTH TO
NORTHWEST WINDS SLOWLY SUBSIDE TODAY WITH LOW PRESSURE PULLING OFF
TO THE NORTHEAST. BRIEF BREAK IN THE ACTION EXPECTED THIS EVENING
BEFORE WINDS BECOME GUSTY WEST TO WEST SOUTHWEST LATE TONIGHT AND
FRIDAY. WILL LIKELY NEED ADDITIONAL ADVISORIES FOR THIS PERIOD.
MSB
&&
.AVIATION.../ISSUED AT 629 AM/...VALID FOR 12Z TAFS
MVFR DOMINATED FORECAST UNDER LOW CLOUD FIELD AS REMNANT
MOISTURE FROM A DEPARTING STORM SYSTEM INTERACTS WITH INCREASINGLY
FAVORABLE LAKE PROCESSES. LINGERING SNOW THIS MORNING WILL TRANSITION
TO LAKE EFFECT SNOW SHOWERS...ESPECIALLY TARGETING KTVC FOR REDUCED
VISIBILITIES. GUSTY NORTH TO NORTHWEST WINDS TODAY WILL DECREASE IN
SPEED AS THEY BACK WESTERLY LATER TONIGHT. SNOW SHOWERS WILL
INCREASE IN INTENSITY THIS EVENING NEAR KTVC...WITH SNOW SHOWERS
MOVING NORTH TOWARDS KPLN LATER TONIGHT.
MSB
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO NOON EST
FRIDAY FOR MIZ020-021-025>027.
LM...SMALL CRAFT ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR LMZ323-
341-342-344>346.
LH...SMALL CRAFT ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR
LHZ345>349.
LS...SMALL CRAFT ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR LSZ321-
322.
&&
$$
