Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 241719
AFDAPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
1219 PM EST WED DEC 24 2014

.UPDATE...
ISSUED AT 1215 PM EST WED DEC 24 2014

THERE IS OVERWHELMING MODEL CONSENSUS OF A FARTHER EAST MOVEMENT
OF SURFACE LOW. THEREFORE...QPF IS NOT EXPECTED TO BE QUITE AS
ROBUST. AS A RESULT...HAVE TWEAKED SNOW ACCUMULATION AMOUNTS DOWN
A SMIDGEN.

UPDATE ISSUED AT 1025 AM EST WED DEC 24 2014

MODELS HAVE PRETTY MUCH SETTLED ON A FARTHER EAST TRACK OF THE
SURFACE LOW...PASSING EAST OF THE THUMB. THIS LEADS TO A COUPLE
MORE QUESTIONS...AS IF WE DIDN`T HAVE ENOUGH ALREADY. EXPECT A
QUICKER CHANGE OVER TO SNOW THAN PREVIOUSLY ADVERTISED FOR THE
LAKE HURON SHORELINE COUNTIES WITH A FEW INCHES OF ACCUMULATION
NOW POSSIBLE. THEREFORE...WENT AHEAD AND EXPANDED THE WINTER
WEATHER ADVISORY OUT THERE AS WELL (TO BEGIN AT 8 PM). IN
ADDITION...MAY HAVE TO ADJUST HEAVIER AXIS OF QPF A LITTLE FARTHER
EAST. THE HEAVIEST SNOW IS STILL EXPECTED ACROSS THE HIGHER
TERRAIN OF NORTHWEST LOWER.

&&

.NEAR TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 420 AM EST WED DEC 24 2014

HIGH IMPACT WEATHER POTENTIAL: HIGH CONFIDENCE NOW FOR A STRIPE OF
ACCUMULATING SNOW ACROSS NORTHERN MICHIGAN. LOWER CONFIDENCE IN THE
EXACT SPOTS THIS WILL OCCUR...BUT LATEST TRENDS CONTINUE TO SUGGEST
PARTS OF NORTHWEST LOWER AND FAR EASTERN UPPER MICHIGAN WILL BE
IMPACTED...WITH THE GREATEST IMPACT LIKELY OVER THE HIGHER TERRAIN
WHERE TEMPERATURES WILL BE JUST A DEGREE OR TWO COLDER. WET AND
HEAVY NATURE OF THE SNOW...COMBINED WITH THE POTENTIAL FOR BANDED
LOCALIZED ENHANCED ACCUMULATION AND WINDY CONDITIONS WEDNESDAY NIGHT
COULD LEAD TO SOME DOWNED TREES AND POWER OUTAGES.

HANG ONTO YOUR HATS - HERE WE GO! MUCH-ADVERTISED STORM EVENT FOR
THE PAST 7 DAYS IS WELL ON ITS WAY TO TAKING SHAPE...WITH OUR
INITIAL WEAKER SURFACE LOW MEANDERING OVER THE WESTERN LAKES AND
GRADUALLY FILLING...WHILE A STRONG MID CONUS TROUGH CONTINUES TO
SLOWLY AMPLIFY ON THE HEELS OF A 130 KNOT JET CORE SLICING DOWN THE
HIGH PLAINS. PRIMARY SHORTWAVE WE HAVE BEEN FOLLOWING FOR SOME TIME
IS JUST NOW ROUNDING THE BASE OF THAT TROUGH...WITH INCREASING UPPER
DIVERGENCE/JET FORCING SUPPORTING SURFACE CYCLOGENESIS OVER
MISSISSIPPI AS OF 04Z. QUITE THE MOISTURE PLUME WITH THIS SECONDARY
SYSTEM...WITH PWAT VALUES ABOVE 1.5 INCHES DOWN ALONG THE GULF...
SUPPORTING SEVERAL REPORTS OF SEVERE WEATHER/TORNADOES DOWN THAT WAY
(VERY SAD TO HEAR ABOUT EARLIER FATALITIES)...WHILE UP THIS WAY...
PASSAGE OF EARLIER PRECIP-FORCING OCCLUDED FRONTAL BOUNDARY IS NOW
ALLOWING FOR THE BRIEF ARRIVAL OF DRIER AIR. THAT HAS SCOURED OUT
LOW CLOUDS AS WE SIT IN THE "WARM" SECTOR OF THE OCCLUDING CYCLONE
TO OUR WEST...BUT WITH SOUPY CONDITIONS FAVORING SOME RATHER DENSE
FOG IN SPOTS THANKS TO BOUNDARY LAYER COOLING AND WET GROUND.

FINALLY...AFTER SO MUCH MODEL TURMOIL THE PAST FEW DAYS...CONFIDENCE
IS QUITE HIGH ON THE FINAL TRACK OF OUR SURFACE LOW. INCREASING
UPPER SUPPORT WILL CONTINUE TO FAVOR DEEPENING AS THE SYSTEM LIFTS
TO A POSITION FROM NEAR TOLEDO AT MID AFTERNOON TO THE THUMB THROUGH
LATE EVENING...AND THEN ON INTO WESTERN ONTARIO/WESTERN QUEBEC BY
CHRISTMAS MORNING. THIS STORM TRACK IS A CLASSIC ONE FOR MANY
NORTHERN MICHIGAN WINTER WEATHER ENTHUSIASTS...THOUGH THE ONLY THING
TRULY LACKING THIS GO AROUND IS A COLDER AIRMASS. INSTEAD...WE ARE
STUCK WITH MARGINAL CONDITIONS AND WILL HAVE TO RELY ON DYNAMICAL
PROCESSES TO REALLY HELP COOL DOWN THE ATMOSPHERE FOR SNOW POTENTIAL.

WITH THAT SAID...ALL SIGNS ARE A GO FOR RAPID CLOSING OFF OF THE MID
LEVEL CYCLONE...FAVORING ELONGATING LOW/MID LEVEL DEFORMATION
FORCING EXPANDING UP THROUGH NORTHERN MICHIGAN THIS MORNING. IN
FACT...ALREADY SEEING THE FIRST HINTS OF THIS WITH MID LEVEL RETURNS
SHOWING UP. GIVEN THE WARMER BOUNDARY LAYER WELL INTACT EARLY THIS
MORNING...SUSPECT THE FIRST PERIODS OF PRECIP WILL LIKELY FALL AS
RAIN FOR ALL AREAS...UP UNTIL THE POINT THAT VERY STRONG SLOPED
FRONTOGENETICAL FORCING AXIS ROLLS UP INTO THIS REGION THROUGH THE
AFTERNOON. EXPECTED TRACK OF NEARLY STACKED SYSTEM SUGGESTS A
TURNING OF THE 850-700MB FLOW MORE NORTHERLY AFTER 18Z...HELPING
DRAG IN SUFFICIENTLY COOLER AIR ALOFT TO ERADICATE THE INITIAL WARM
NOSE OVER THE HIGHER TERRAIN AND PARTS OF THE EASTERN U.P./NORTHWEST
LOWER...ALL WHILE THAT SAME FLOW WILL TAP "WARMER" AIR WRAPPING IN
AHEAD OF THE STORM FOR EASTERN AREAS. COUPLE THAT SETUP WITH
ADDITIONAL COOLING VIA INTENSE UPWARD VERTICAL MOTION AND HAVE TO
BELIEVE BASED ON HISTORY THAT WE WILL SEE PRECIP RAPIDLY SWITCH TO
SNOW...DESPITE WHAT MAY BE LINGERING WARMER BOUNDARY LAYER TEMPS OF
33-35F. HIGHER TERRAIN SHOULD ALSO PLAY INTO THAT...WITH TEMPS JUST
A SHADE COOLER IN THE 31-32F RANGE...SUGGESTIVE THAT OUR HEAVIEST
ACCUMULATION MAY WELL LINE UP WITH THE SPINE OF HIGHEST ELEVATION.

AS FOR ACCUMULATION POTENTIAL...PLENTY OF GULF MOISTURE WRAPPING
INTO THIS SYSTEM IS A CAUSE FOR CONCERN...AS IS ITS RAPIDLY
OCCLUDING NATURE. SUCH SYSTEMS OFTEN OVER-PRODUCE IN A NARROW STRIPE
FROM WHAT IS EXPECTED...AND HAVE INCREASING CONCERNS ABOUT A NARROW
BUT VERY HEAVY STRIPE OF SNOWS ADVANCING OVER PARTS OF THE AREA. NAM
GUIDANCE IS ESPECIALLY TROUBLING...WITH QPF VALUES IN EXCESS OF 1.2
INCHES NOT OUT OF THE REALM OF POSSIBILITY...THOUGH NOT OVERLY
LIKELY EITHER. BULK OF 00Z GUIDANCE TRENDED A SHADE EAST WITH THE
SURFACE LOW TRACK...WHICH OF COURSE TUGS THE BEST PRECIP POTENTIAL
IN THAT DIRECTION AS WELL...THOUGH WITH THE MID LEVEL LOW CLOSING
OFF OVERHEAD...IT MAY NOT BE AS FAR EAST AS THE 00Z SUITE WOULD
SUGGEST. NEVERTHELESS...COUPLE THE FGEN-DRIVEN STRIPE OF HEAVY
PRECIP WILL A TERRAIN COMPONENT...AND HAVE TO AT LEAST ACKNOWLEDGE
THE POTENTIAL FOR SOME SPOTS TO PICK UP LOCALIZED WARNING LEVEL
SNOWS. IN ADDITION...OMEGA SIGNATURES CONTINUE TO BE DECENT...WITH
DEEP LAYER OMEGA BISECTING A DEEPER -12C TO -18C WEDGE OF COLD AIR
ALOFT...SUPPORTING OF ENHANCED DENDRITIC GROWTH POTENTIAL DESPITE
WARMER PROFILES BELOW. AS IF THAT`S NOT ENOUGH... TIME HEIGHTS HAVE
FOR SEVERAL DAYS SUGGESTED AN INTRUSION OF NEGATIVE THETA-E LAPSE
RATES IN THE 800-600MB LAYER...GIVING AT LEAST THE POSSIBILITY SOME
THUNDER COULD BE THROWN INTO THE MIX.

NOW...WHAT TO DO WITH HEADLINES? SHOULD MENTION THAT CONFIDENCE
ISN`T AS HIGH AS I WOULD LIKE EVEN AT THIS RANGE...BUT GUT FEELING
IS TO DOWNGRADE MUCH OF THE WATCH TO AN ADVISORY...HITTING THE
WORDING HARDEST OVER THE HIGH TERRAIN (4 TO AS MUCH AS 8 INCHES).
NOT REALLY SO SURE EASTERN UPPER WILL GET TO ADVISORY LEVELS WITH A
SHARP WESTWARD CUTOFF TO PRECIP. WILL THUS FOREGO ANY HEADLINE UP
THAT WAY...WITH UP TO 3-4" OVER FAR EASTERN SPOTS. IN A SIMILAR
VEIN...WILL DROP ANY HEADLINES FROM LEELANAU DOWN TO MANISTEE COUNTY
AS THOSE SPOTS AGAIN LIE ON THE WESTERN FRINGE OF EXPECTED BETTER
PRECIP...AND A SLOWER TRANSITION NEAR THE COAST WILL REALLY CUT DOWN
ON ANY ACCUMULATION. WILL ALSO TACK ON AN EASTWARD TIER OF COUNTIES
TO THE ADVISORY AS THE ABOVE-MENTIONED LAST MINUTE EASTWARD SHIFT
WOULD SUPPORT A FASTER TRANSITION EAST OF I-75. IT SHOULD BE
MENTIONED THAT OF COURSE ANY LAST MINUTE WOBBLES WILL MEAN POSSIBLE
HEADLINE/ACCUMULATION CHANGES...AND IT`S NOT ENTIRELY IMPOSSIBLE FOR
A NARROW STRIPE OF WARNING-LEVEL SNOWS TO IMPACT PARTS OF THE I-75
CORRIDOR.

&&

.SHORT TERM...(THURSDAY THROUGH FRIDAY NIGHT)
ISSUED AT 420 AM EST WED DEC 24 2014

...UNSETTLED WEATHER INTO THE WEEKEND...TURNING COLD NEXT WEEK...

PATTERN OVERVIEW AND FORECAST: THREE-WAVE LONG WAVE PATTERN IN PLACE
ACROSS THE NRN HEMISPHERE THIS MORNING WITH A DEEPENING LONG WAVE
TROUGH AXIS ACROSS THE CENTRAL CONUS AND LONG WAVE RIDGING IN PLACE
IN THE EASTERN PACIFIC INTO THE WEST COAST OF NOAM. LONG WAVE
PATTERN LOOKING TO UNDERGO STRONG AMPLIFICATION OVER THE NEXT
SEVERAL DAYS AS SHARP RIDGING REDEVELOPS JUST OFF THE WEST COAST AND
DEEP LONG WAVE TROUGHING DEVELOPS ACROSS CENTRAL AND EASTERN CANADA
INTO THE GREAT LAKES. THIS SIGNALS A RETURN TO FAIRLY COLD
CONDITIONS FROM THE PLAINS TO GREAT LAKES IN THE 5 TO 10 DAY TIME
FRAME AND DAYTIME TEMPS DIPPING BACK INTO THE TEENS TO 20S BY MID
NEXT WEEK.

IN THE SHORTER TERM...DEEP SHORT WAVE TROUGH AND STRONG SHORT WAVE
ENERGY IS NOW LIFTING OUT OF THE GULF COAST THIS MORNING...WHICH OF
COURSE WILL BRING US OUR CHRISTMAS EVE/DAY SNOW EVENT. UPSTREAM...
ANOTHER STRONG WAVE NOTED COMING ONSHORE IN THE PAC NW THIS MORNING.
THIS NEXT SYSTEM WILL DIG INTO THE PLAINS OVER THE NEXT 1 TO 2
DAYS...BEFORE ULTIMATELY OPENING UP AND ADVANCING THROUGH THE GREAT
LAKES LATE IN THE WEEK INTO THE WEEKEND.

CHRISTMAS DAY/NIGHT...POTENT PHASING SHORT WAVE AND ATTENDING SFC
LOW/DEFORMATION PRECIP WILL ALREADY HAVE EXITED QUICKLY NORTHEAST
THROUGH WESTERN QUEBEC BY CHRISTMAS MORNING...WITH SFC RIDGING/
SUBTLE SHORT WAVE RIDGING NOSING INTO THE REGION THROUGH THE DAY.
COULD BE A LITTLE LAKE INDUCED LIGHT SNOW SHOWERS HANGING BACK
ACROSS EASTERN UPPER/NW LOWER MICHIGAN EARLY THURSDAY MORNING AS LOW
LEVEL TEMPS BRIEFLY COOL JUST ENOUGH TO SUPPORT LAKE EFFECT.
ALSO...SOME HINT OF A LOW-MID LEVEL CONFLUENT FLOW AXIS AND SOME
VERY LIGHT NUISANCE SNOW/FLURRIES MIGHT TRY TO NOSE INTO THE WESTERN
GREAT LAKES LATER IN THE DAY...BEFORE PIVOTING UP INTO THE UPPER
GREAT LAKES BY FRIDAY. BUT OTHERWISE...MAINLY CLOUDY SKIES WILL BE
THE RULE THROUGH MUCH OF THE DAY AND THURSDAY NIGHT WITH DAYTIME
TEMPS IN THE MIDDLE 30S AND LOWS IN THE UPPER 20S TO LOWER 30S.

FRIDAY...AFOREMENTIONED PACIFIC SHORT WAVE DIGS INTO THE SW CONUS ON
FRIDAY HELPING TO PUMP UP DOWNSTREAM RIDGING ACROSS THE EASTERN
CONUS AND KICK SOME SLIGHTLY WARMER AIR INTO THE STATE. MIGHT EVEN
SEE A LITTLE BIT OF THINNING CLOUD COVER LATER THURSDAY NIGHT INTO
FRIDAY AS THAT WARMER/DRIER AIR MAKES IT/S WAY NORTHWARD. BUT
OVERALL DRY WEATHER WILL CONTINUE TO PREVAIL THROUGH THE DAY FRIDAY
INTO FRIDAY EVENING.

FRIDAY NIGHT INTO SATURDAY...SHORT WAVE ENERGY FORECAST TO EJECT
OUT OF THE SW CONUS AND ROCKET NE UP THROUGH THE WESTERN GREAT
LAKES...RESULTING INTO ANOTHER DEEPENING LOW PRESSURE SYSTEM THAT
TRACKS THROUGH THE REGION. APPEARS LIKELY THAT WE SEE ANOTHER
BATCH OF PRECIP SLIDE UP THROUGH THE REGION LATE FRIDAY NIGHT INTO
SATURDAY. BUT...WITH THERMAL RIDGING UP INTO THE STATE...PRECIP
TYPE MAY ONCE AGAIN BE AN ISSUE FRIDAY NIGHT AND THERMAL PROFILES
SUGGEST A TRANSITION TO MORE IN THE WAY OF LIQUID (RAIN OR
FREEZING RAIN POSSIBILITIES) HEADING TOWARD SAGINAW BAY. OF
COURSE...THAT/S STILL A FEW DAYS OUT AND WE CAN DEAL WITH THE
DETAILS AT A LATER TIME. FOR NOW...HAVE JUST A RAIN/SNOW MIX IN
THE FORECAST FOR PARTS OF NRN LOWER MICHIGAN FRIDAY NIGHT BEFORE
TRANSITIONING BACK TO SNOW ON SATURDAY AS COLDER AIR BLEEDS BACK
INTO REGION.

&&

.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
ISSUED AT 415 PM EST TUE DEC 23 2014

PATTERN LOOKS TO REMAIN ACTIVE WITH SOME WEAKER DISTURBANCES COMING
THROUGH THE REGION BEHIND THE LARGER CHRISTMAS TIME SYSTEM. CHANCES
FOR SNOW THROUGHOUT THE EXTENDED PERIOD FROM THESE
DISTURBANCES...WITH A WEAKENING LOW FROM THE LEE OF THE ROCKIES OVER
THE WEEKEND...A CLIPPER SYSTEM COMING THROUGH EARLY IN THE WEEK AND
CHANCES FOR LAKE EFFECT SNOWS BEHIND THAT. FRIDAY EVENING INTO
SATURDAY WILL SEE RAIN CHANGING TO SNOW FOR MOST OF NORTHERN LOWER
AS ABOVE FREEZING AFTERNOON TEMPERATURES COOL BELOW FREEZING. WHILE
SATURDAY HIGHS WILL BE ABOVE NORMAL IN THE MID 30S...THE REMAINDER
OF THE PERIOD WILL SEE HIGHS IN THE LOW 20S. OVERNIGHT LOWS ON
FRIDAY WILL ALSO BE ABOVE NORMAL IN THE LOW 30S...THAT TOO WILL
CHANGE AS WE GET BACK TO MORE NORMAL LOWS IN THE TEENS FOR THE REST
OF THE PERIOD.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 655 AM EST WED DEC 24 2014

LOW PRESSURE SYSTEM WILL ROCKET N/NE UP THROUGH THE CENTRAL GREAT
LAKES REGION OVER THE NEXT 12 TO 18 HOURS...PASSING UP THROUGH
LAKE HURON. AXIS OF PRECIPITATION WILL LIFT UP INTO THE REGION
THROUGH THE MORNING HOURS AND BECOME HEAVIEST THIS AFTERNOON
THROUGH THIS EVENING. HOWEVER...PRECIP TYPE WILL BE PROBLEMATIC.
INITIALLY... MAINLY RAIN IS EXPECTED AT THE TERMINAL SITES
THROUGH THIS MORNING. BUT PRECIP WILL BEGIN TO CHANGE OVER TO SNOW
AT TVC/MBL/PLN BETWEEN 18Z AND 22Z THIS AFTERNOON...AND AFTER 02Z
AT APN. SEVERAL INCHES OF WET SNOW WILL IMPACT THE TERMINAL SITES
THROUGH THIS EVENING.

SNOWFALL WINDS DOWN QUICKLY LATE THIS EVENING AND OVERNIGHT AND
MAY END IN A PERIOD OF LIGHT DRIZZLE OR FREEZING DRIZZLE.

WINDS...LIGHT THROUGH THE DAY. BUT WINDS WILL CRANK UP LATE THIS
AFTERNOON THROUGH TONIGHT FROM THE N/NW WITH GUSTS AROUND 25 KNOTS
THROUGH TONIGHT.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...WINTER WEATHER ADVISORY UNTIL 7 AM EST THURSDAY FOR MIZ016>019-
     021>023-026>029-032>034.

     WINTER WEATHER ADVISORY FROM 8 PM THIS EVENING TO 7 AM EST
     THURSDAY FOR MIZ024-030-035-036-041-042.

LH...SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 11 AM EST
     THURSDAY FOR LHZ345-346.

     GALE WARNING FROM 7 PM THIS EVENING TO 11 AM EST THURSDAY FOR
     LHZ347>349.

LM...SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 11 AM EST
     THURSDAY FOR LMZ323-341.

     SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 5 PM EST THURSDAY
     FOR LMZ342-344>346.

LS...SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 11 AM EST
     THURSDAY FOR LSZ321-322.

&&

$$

UPDATE...SULLIVAN
NEAR TERM...LAWRENCE
SHORT TERM...ADAM
LONG TERM...ALM
AVIATION...ADAM



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