Area Forecast Discussion
Issued by NWS Gaylord, MI

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000
FXUS63 KAPX 262302
AFDAPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
602 PM EST WED NOV 26 2014

.SYNOPSIS...
ISSUED AT 557 PM EST WED NOV 26 2014

ANOTHER SHOT OF ARCTIC AIR ALONG WITH SNOW SHOWERS WILL MOVE IN
TONIGHT INTO THANKSGIVING DAY. MILDER AIR TRYING TO OVERRUN THE COLD
AIR FRIDAY INTO FRIDAY NIGHT WILL LIKELY BRING MORE SNOW SHOWERS TO
THE REGION. MILD CONDITIONS ARE THEN EXPECTED SATURDAY OUT AHEAD OF
YET ANOTHER SHOT OF COLD AIR THAT IS DUE IN ON SUNDAY.

&&

.SHORT TERM...(THIS EVENING THROUGH TONIGHT)
ISSUED AT 401 PM EST WED NOV 26 2014

HIGH IMPACT WEATHER POTENTIAL: LOCALIZED HEAVY SNOW ACCUMULATIONS
OVER PARTS OF NORTHEAST LOWER...AND A BURST OF HEAVY SNOW EXPECTED
FOR MUCH OF EASTERN UPPER/NORTHWEST LOWER TOWARD MORNING AS AN
ARCTIC COLD FRONT ARRIVES.

MESOSCALE MADNESS ON THE GREAT LAKES AT THE MOMENT...COURTESY OF A
VERY LIGHT FLOW REGIME IN PLACE AS LOW LEVEL RIDGING IS DRAPED FROM
QUEBEC BACK THROUGH LOWER MICHIGAN. THAT LIGHT FLOW COUPLED WITH
NATURAL THERMALLY-INDUCED OVER-WATER TROUGH DEVELOPMENT AND ENHANCED
LOCAL CONVERGENCE AXES VIA EARLIER LAND BREEZE CIRCULATIONS HAS LED
TO NUMEROUS POCKETS OF LOCALIZED HEAVIER SNOW SHOWERS OVER THE PAST
FEW HOURS. REALLY HARD TO GET A FULL FEELING FOR JUST HOW WIDESPREAD
THE SNOW SHOWERS/MESOSCALE VORTICES ARE AS WE ARE OVERSHOOTING MUCH
OF THE ACTION ON RADAR...BUT HI-RES SHORT TERM GUIDANCE HAS BEEN
QUITE THE HELP IN ATTEMPTING TO FIGURE OUT JUST WHERE THESE THINGS
MAY LIE. ONE BAND OF NOTE STRETCHES FROM NORTHERN LAKE HURON UP THE
ST. MARYS RIVER INTO SOO...WITH VISBY REDUCTIONS TO AROUND 1SM AT
TIMES SUGGESTING SOME ACCUMULATION IS ONGOING. ANOTHER BAND LIES UP
THE SPINE OF LAKE MICHIGAN INTO WESTERN MACKINAC AND LUCE
COUNTIES...WHILE A MYRIAD OF FLURRIES CONTINUE ACROSS MUCH OF
NORTHERN LOWER...COURTESY OF A CLOUD DECK SITTING SQUARELY IN THE
DGZ.

BIGGEST CHALLENGE FOR TONIGHT IS LOCALIZED SNOW ACCUMULATION
POTENTIAL. APPROACH OF OUR NEXT NORTHERN STREAM WAVE AND ASSOCIATED
ARCTIC COLD FRONT WILL HELP FLEX THE EXISTING LAKE AGGREGATE TROUGH
OVER LAKE HURON BACK SOUTHWEST WITH TIME...SETTING UP A LOCALIZED
AXIS OF QUITE STRONG CONVERGENCE FROM THE ST. MARY`S RIVER SOUTHWARD
AND CLIPPING MAINLY EASTERN PARTS OF PRESQUE ISLE/ALPENA/ALCONA
COUNTIES. ALL THE WHILE...WARMER AIR OVER THE WATER WILL ESSENTIALLY
ACT IN THE SAME MANNER AS A TROWAL...HELPING LIFT PARCELS UP THE LOW
LEVEL ISENTROPIC SURFACE AND TIGHTENING A VERY NARROW CORRIDOR OF
LOW LEVEL FGEN ALONG THE LAND/WATER INTERFACE. COUPLE THAT PHYSICAL
PROCESS WITH PLENTIFUL LAKE INSTABILITY AND A DEEPENING DGZ...AND
THERE IS THE POTENTIAL FOR SOME SNEAKY VERY HEAVY ACCUMULATION OVER
PARTS OF SAID AREA ABOVE...CONTINUING INTO TOMORROW AS WELL (SEE
BELOW FOR MORE ON THAT). ACTUALLY SAW A SIMILAR SCENARIO A FEW YEARS
AGO UP ALONG THE ST MARYS RIVER/WHITEFISH BAY INTERFACE WHICH
RESULTED IN ACCUMS IN EXCESS OF 8". THIS ONE CERTAINLY HAS THE
POTENTIAL TO PRODUCE SIMILAR ACCUMULATION...AND WITH THAT IN MIND
AND WITH COORDINATION OF LONG TERM FORECASTER...WILL BE KICKING OUT
AN ADVISORY FOR THE ABOVE-MENTIONED COUNTIES.

MEANWHILE...INCOMING ARCTIC BOUNDARY AND SUBSEQUENT UPTICK IN LOW
LEVEL CONVERGENCE SHOULD "SCOOP UP" ANY MID LAKE BANDING OVER LAKES
SUPERIOR/MICHIGAN AND EFFECTIVELY PUNT IT INLAND AFTER 08Z TONIGHT.
NICE PUSH OF DEEPER LAYER MOISTURE AND UPPER FORCING SHOULD FORCE
SNOW SHOWERS INLAND OVER MUCH OF THE REMAINDER OF EASTERN UPPER AND
NORTHWEST LOWER...WITH ACCUMULATION OF MAYBE 1-2" CLOSER TO THE
LAKESHORES...TAPERING INLAND. ALL IN ALL...A TOUGH FORECAST WITH
LATE NIGHT ADJUSTMENTS MORE THAN LIKELY ONCE WE SEE EXACTLY WHERE
THE BETTER BANDS OF SNOW DECIDE TO SET UP.

.LONG TERM...(THURSDAY THROUGH WEDNESDAY)
ISSUED AT 401 PM EST WED NOV 26 2014

...PERIODIC SNOW CHANCES INTO THE WEEKEND...

HIGH IMPACT WEATHER POTENTIAL: POTENTIAL FOR A PERIOD OF HEAVY SNOW
DURING THE FIRST HALF OF THANKSGIVING DAY ALONG THE US-23 CORRIDOR
BETWEEN ROGERS CITY AND OSCODA.  MORE WIDESPREAD MOSTLY LIGHT SNOW
FOR FRIDAY THROUGH FRIDAY EVENING...SOME ENHANCED SNOWFALL
AMOUNTS POSSIBLE OVER WESTERN MACKINAC COUNTY.

PATTERN SYNOPSIS/FORECAST: DEEP LONG WAVE TROUGH ENTRENCHED OVER
NORTH AMERICA...WITH ANOTHER LONG WAVE TROUGH OVER EASTERN ASIA
CUTTING THE NORTHERN HEMISPHERE NEATLY IN HALF.  BIT OF A REX BLOCK
LOOK TO THINGS OVER THE PACIFIC BETWEEN 140-160W.  SPLIT IN THE
NORTH AMERICAN MEAN TROUGH WITH A PAIR OF SHORT WAVE TROUGHS MOVING
THROUGH THE SOUTHERN BRANCH...ONE OVER THE MID MISSISSIPPI VALLEY
AND A SECOND SWINGING THROUGH THE SOUTHEASTERN U.S. AND CAUSING
MISCHIEF ALONG THE EAST COAST DURING PRIME PRE-THANKSGIVING TRAVEL
TIME.  BROAD POSITIVE TILT SHORT WAVE TROUGH IN THE NORTHERN BRANCH
EXTENDS FROM HUDSON BAY INTO NORTH DAKOTA/MINNESOTA.  SURFACE LOW
PRESSURE CENTERS ASSOCIATED WITH THE SOUTHERN BRANCH WAVES OVER
SOUTHEAST IOWA AND ALONG THE CAROLINA COAST.  SLOW MOVING FRONT
ASSOCIATED WITH NORTHERN STREAM WAVE ACROSS NORTHERN ONTARIO/LAKE
SUPERIOR/NORTHERN MINNESOTA WITH A 1036MB ARCTIC HIGH OVER CENTRAL
CANADA ASSOCIATED WITH SOME BRUTALLY COLD TEMPERATURES (TEENS AND
20S BELOW ZERO ACROSS SASKATCHEWAN/MANITOBA/NORTHWEST ONTARIO).
COMBINATION OF NORTHERN BRANCH WAVE OVER ONTARIO AND SOUTHERN BRANCH
FEATURE OVER IOWA IS SPREADING SNOW ACROSS MUCH OF THE MIDWEST AND
PARTS OF THE UPPER LAKES REGION.

NORTHERN BRANCH SHORT WAVE TROUGH WILL CROSS MICHIGAN THANKSGIVING
MORNING...WITH THERMAL TROUGHING ARRIVING BEHIND THIS FEATURE.  THIS
WILL BE FOLLOWED QUICKLY BY LOW/MID LEVEL WARM ADVECTION THURSDAY
NIGHT/FRIDAY AS SURFACE RIDGING MOVES THROUGH THE UPPER LAKES AND
UPPER LEVEL FLOW TRENDS TOWARD A FLATTER LOOK WITH LOW AMPLITUDE
RIDGING SPREADING INTO THE CENTRAL U.S..  THIS ALLOWS FOR MORE OF A
PACIFIC ORIGIN AIR MASS SPREADING ACROSS THE COUNTRY FOR THE LATTER
HALF OF THE HOLIDAY WEEKEND.

PRIMARY FORECAST CONCERNS (NEAR TERM): VARYING SNOW CHANCES BETWEEN
SHORT WAVE PASSAGE THURSDAY MORNING...FOLLOWED BY AFTERNOON COLD
ADVECTION/LAKE CONVECTION INTO THURSDAY NIGHT...THEN WARM ADVECTION
MORE WIDESPREAD SNOWFALL EXPECTED FRIDAY.

NEAR TERM (THURSDAY/FRIDAY/SATURDAY): SNOW SHOULD BE ONGOING AT
DAYBREAK THANKSGIVING MORNING...THOUGH EXPECT THE SYNOPTIC PORTION
OF THIS TO WIND DOWN FROM WEST TO EAST AS THE MORNING PROGRESSES.
ALTHOUGH OVERALL ACCUMULATIONS FROM THIS PART OF THE SYSTEM EXPECTED
TO BE ON THE LIGHT SIDE...CONCERNED ABOUT COUNTIES ADJACENT TO LAKE
HURON WITH THE POSSIBILITY OF SOME FOCUSED CONVERGENCE ALONG A COLD
FRONT DROPPING INTO LOWER MICHIGAN OVERNIGHT.  POTENTIAL EXISTS FOR
MESOSCALE ENHANCEMENT OF SNOWFALL RATES DUE TO LAKE INDUCED
CONVECTION ALONG AND NEAR THIS BOUNDARY...POSSIBLY DUE TO
DEVELOPMENT OF A LOW LEVEL CIRCULATION THAT WILL "SPIN" HEAVIER SNOW
BACK INTO NORTHEAST LOWER.  DETERMINING EXACTLY WHERE THIS POTENTIAL
"SNOW FLASH FLOOD" EVENT SETS UP IS THE TRICK...AS ANYWHERE ALONG
THE US-23 CORRIDOR FROM CHEBOYGAN DOWN TO TAWAS CITY WILL BE
SUSCEPTIBLE THOUGH PREFERENCE RIGHT NOW IS TO FOCUS BEST POTENTIAL
ON THE STRETCH BETWEEN ROGERS CITY AND OSCODA WITH 2-6 INCHES IN
GENERAL WITH HIGHER AMOUNTS EXPECTED TO BE MORE LOCALIZED AND MAY
FOCUS MORE ON THE US-23 CORRIDOR ITSELF.  GIVEN POTENTIAL FOR TRAVEL
HEADACHES FOR FOLKS TRYING TO GET GOING THANKSGIVING MORNING...AN
INITIAL ADVISORY FOR PRESQUE ISLE/ALPENA/ALCONA COUNTIES WILL BE
ISSUED...HOLDING OFF ON IOSCO COUNTY FOR NOW AS THIS WILL BE MORE OF
A SECOND PERIOD PROBLEM AND WILL HAVE SOME TIME TO EVALUATE HOW
SNOWFALL IS EVOLVING TOMORROW MORNING.  MAY ALSO SEE SOME HEAVIER
SNOWFALL CLIP EXTREME SOUTHEAST UPPER/DRUMMOND ISLAND AS WELL AS
TAIL END OF STRONGER CONVERGENCE AXIS MAY REACH THIS FAR NORTH.
REMAINDER OF THE FORECAST AREA LIKELY TO SEE AN INCH OR LESS OF
SNOWFALL DURING THE MORNING...THOUGH COULD BE A LITTLE MORE OVER
NORTHWEST LOW WITH FLOW OFF LAKE MICHIGAN.  SO AFTER ALL THAT...
STILL NEED TO DEAL WITH THE REST OF THE DAY.  THIS SHOULD CONSIST
MORE PURE LAKE CONVECTION WITHIN A 320-330 FLOW REGIME...LOOKS TO BE
FAIRLY SHALLOW WITH INVERSION HEIGHTS NEAR OR BELOW 850MB WITH
SYNOPTIC DRYING/SUBSIDENCE OVERSPREADING THE FORECAST AREA.  SO
DON`T ANTICIPATE LAKE SNOWS WILL GET TOO OUT OF HAND HEADING INTO
THURSDAY AFTERNOON/EVENING...WITH LOW LEVEL WINDS WEAKENING/BACKING
DURING THE NIGHT.

WARM ADVECTION MID/HIGH CLOUDS WILL SPREAD ACROSS NORTHERN MICHIGAN
DURING THE EARLY MORNING HOURS OF FRIDAY...WITH SNOW EXPECTED TO
COMMENCE FROM WEST TO EAST DURING THE MORNING/EARLY AFTERNOON ONCE
INITIALLY DRY LOWER LAYERS SATURATE.  A GENERAL 1-3 INCHES EXPECTED
FRIDAY THROUGH FRIDAY EVENING...WITH SOUTHERLY FLOW OFF LAKE
MICHIGAN LIKELY ENHANCING AMOUNTS OVER WESTERN MACKINAC COUNTY (2-5
INCHES).  MID LEVELS FORECAST TO DRY OUT DURING THE EARLY MORNING
HOURS SATURDAY...SO SNOW MAY TAPER OFF TO JUST FLURRIES OR A PERIOD
OF FREEZING DRIZZLE.

SATURDAY MAY SEE ANOTHER ROUND OF WARM ADVECTION DRIVEN PRECIP...BUT
WARMING TEMPERATURES MAY ALSO LEAD TO THE POSSIBILITY OF SOME RAIN
ESPECIALLY ACROSS NORTHERN LOWER WITH TEMPERATURES RISING INTO THE
30S.

JPB

EXTENDED RANGE: SATURDAY NIGHT: THE MAIN ISSUE REVOLVES AROUND IF
ANY AND WHAT TYPE OF PRECIP MIGHT FALL EARLY SATURDAY EVENING
ACROSS THE TIP OF THE MITT INTO EASTERN UPPER BEFORE H8 TEMPS RISE
ABOVE 0C CWA-WIDE BY 06Z SUNDAY...LEADING TO ANY MIXED PRECIP
CHANGING OVER TO ALL RAIN SHOWERS.

SUNDAY THROUGH MONDAY: ANY "WARM" AIR SUNDAY MORNING (LOWER 40S LOOK
LIKE A GOOD BET ACROSS FAR SOUTHEASTERN COUNTIES) GETS SHUNTED
EASTWARD SUNDAY AFTERNOON/EVENING WITH THE PASSAGE OF A STRONG COLD
FRONT LEADING TO H8 TEMPS FALLING TO -10 TO -20C BY MONDAY MORNING.
WITH THE COLD AIR COMES A WINDOW MONDAY MORNING THROUGH MONDAY
EVENING FOR ADDITIONAL ACCUMULATING LAKE EFFECT SNOW CHANCES IN
THE NORTHWEST FLOW LAKE EFFECT BELTS.

MONDAY NIGHT THROUGH WEDNESDAY: HIGH PRESSURE CONTINUES TO APPROACH
FROM THE WEST MONDAY EVENING RESULTING IN A MORE TRANSIENT 1000-850
MB FLOW...WHICH SHOULD EFFECTIVELY BRING ANY NOTEWORTHY LAKE SNOWS
TO AN END MONDAY EVENING. ANOTHER WEAK WAVE IS POSSIBLE TOWARD THE
TUESDAY NIGHT-WEDNESDAY TIME FRAME WITH ITS CURRENT PATH
PROVIDING LIGHT SNOW CHANCES TO AT LEAST PART OF THE AREA.

GILLEN

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 557 PM EST WED NOV 26 2014

ALREADY SEEING SCATTERED LAKE EFFECT SNOW HEADING INLAND TOWARD KAPN THIS
EVENING...WHICH COULD POTENTIALLY BRING PERIODS OF IFR/LIFR CONDITIONS
IN HEAVIER SNOWS LATER TONIGHT. CONFIDENCE ON LIFR REMAINS LOW AS SUCH
RESTRICTIONS WILL LIKELY REMAIN VERY LOCALIZED. NONE THE LESS...A FEW
INCHES OF ACCUMULATION POSSIBLE IN THAT AREA WITH MVFR/IFR LIKELY.

FOR THE REMAINDER OF THE TAF SITES: A COLD FRONT IS EXPECTED TO CROSS
THE AREA TONIGHT...BRINGING A ROUND OF SNOWFALL AND MVFR/IFR CONDITIONS
THROUGH TOMORROW MORNING. AN INCH OR TWO OF ACCUMULATION WILL BE POSSIBLE
AS THE SNOW COULD BRIEFLY FALL HEAVY AT TIMES TONIGHT (PRIMARY BETWEEN 07Z
AND 14Z). WINDS WILL ALSO BECOME GUSTY TOWARD SUNRISE THURSDAY...WHICH MAY
LEAD TO SOME OF THAT SNOW BLOWING AROUND. THE STEADIEST SNOW WILL TAPER
BY MIDDAY BEFORE TRANSITIONSTO A FEW ADDITIONAL LAKE EFFECT SNOW SHOWERS
FOR THE AFTERNOON.

&&

.MARINE...
ISSUED AT 401 PM EST WED NOV 26 2014

WEAK GRADIENT ACROSS THE UPPER LAKES THIS AFTERNOON WILL GIVE WAY TO
A MORE ORGANIZED NORTH-NORTHWEST WIND FLOW FOR THURSDAY.  INCREASED
THREAT FOR SMALL CRAFT CONDITIONS WITHIN MOST NEARSHORE ZONES
STARTING THURSDAY MORNING.  WINDS WILL SUBSIDE THURSDAY NIGHT INTO
FRIDAY AS A SURFACE RIDGE CROSSES THE STATE...WITH INCREASING WINDS
FROM THE SOUTH DEVELOPING DURING THE DAY FRIDAY.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 1 PM EST
     THURSDAY FOR MIZ018-024-030.

LH...NONE.
LM...NONE.
LS...NONE.
&&

$$

SYNOPSIS...GILLEN
SHORT TERM...LAWRENCE
LONG TERM...JPB/GILLEN
AVIATION...GILLEN
MARINE...JPB



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