Area Forecast Discussion
Issued by NWS Gaylord, MI

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000
FXUS63 KAPX 190753
AFDAPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
253 AM EST FRI DEC 19 2014

.NEAR TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 240 AM EST FRI DEC 19 2014

...SUNSHINE BUT THE RETURN OF STRATUS FOR SOME...

SYNOPTIC PATTERN AND OBSERVATIONS:

EARLY THIS MORNING...A VERY WAVY UPPER AIR PATTERN ACROSS THE
CONUS...WITH A TROUGH/RIDGE/TROUGH/RIDGE/TROUGH SPANNING FROM THE
WEST COAST TO THE EAST COAST. THE GREAT LAKES IS UNDERNEATH ONE OF
THOSE RIDGES...WITH NO FORCING AND JUST A WEAK NORTHERLY FLOW
TRYING DESPERATELY TO PUSH THE REMAINING STRATUS FURTHER SOUTH OF
THE M-55 CORRIDOR...BUT IT IS SEEMINGLY GETTING HUNG UP IN
MISSAUKEE COUNTY. A MORE IMPRESSIVE PUSH OF DRY AIR WAS SEEN
EARLIER IN UPPER MICHIGAN AND NE WISCONSIN...BUT LATEST SATELLITE
IMAGERY IN PARTS OF WESTERN UPPER IS NOW SHOWING SOME MOISTURE
FLUX OFF THE WATER...FORMING INTO STRATUS OVER THE COLDER GROUND.
THE STRATUS NEVER GOT SCOURED OUT ACROSS FAR WESTERN
WISCONSIN...AND COOLING OF THE BL/WEAKER S/SE FLOW ON THE BACKSIDE
OF SFC HIGH PRESSURE IN THE WESTERN GREAT LAKES...HAS ALLOWED A
NORTH AND NW EXPANSION INTO FAR SW ONTARIO AND THE DAKOTAS. THIS
IS OCCURRING OUT AHEAD OF A VERY WEAK SFC TROUGH WHICH EXTENDS
SOUTHWARD THROUGH THE LEE OF THE ROCKIES. STRATUS WAS ALSO
WIDESPREAD AHEAD OF THIS TROUGH...ALL THE WAY DOWN INTO TEXAS.

FORECAST CHALLENGE: EVOLUTION OF THE STRATUS.

SYNOPTIC PATTERN EVOLUTION AND ASSOCIATED WEATHER:

SFC HIGH PRESSURE WILL SETTLE INTO NRN MICHIGAN TODAY AND REMAINS
OVER US FOR MOST OF TONIGHT. THE WEAK RIDGING ALOFT DOES EXIT
EAST...WHILE A CENTRAL PLAINS TROUGH WORKS INTO THE MID AND UPPER
MISSISSIPPI VALLEY. A WEAK NORTHERLY FLOW IN THE STRATUS/CLOUD LAYER
OUGHT TO CONTINUE TO RESULT IN A VERY SLOW SOUTHWARD DRIVE OF THE
STRATUS. THUS...A SUNNY DAY EXPECTED TODAY. WINDS BECOME NEAR CALM
IN THE CLOUD LAYER HEADING INTO THE EVENING WHEN BL COOLING COULD
TRY AND EXPAND THE STRATUS BACK INTO THE FRANKFORT/MANISTEE AND M-55
CORRIDOR). ALSO...THROUGH TONIGHT...AS THE SFC HIGH EXITS EAST...WE
GET INTO MORE OF A SW FLOW IN THAT SAME CLOUD LAYER. A BIG PLAYER IN
THIS WILL BE HOW MUCH STRATUS WILL BE OVER LAKE MICHIGAN...BUT THIS
WILL LEAVE PORTIONS OF THE NW LOWER LAKESHORES IN A THREAT ZONE FOR
THE RETURN OF STRATUS LATER TONIGHT. OFFSETTING THIS...WOULD BE LAND
BREEZES...SO THE THOUGHT IS THAT THE GREATER PROBABILITY WILL BE FOR
CLOUDS TO REMAIN OFFSHORE. THEN AGAIN...FORECASTING EXACT LOCATIONS
OF CLOUDS...IS A RATHER DAUNTING TASK.

AREAS ALONG AND EAST OF U.S. 131 AND MOST OF EASTERN UPPER EXPECTED
TO REMAIN CLEAR. HIGHS IN THE UPPER 20S AND LOWER 30S WITH LOWS
ANYWHERE FROM THE NEGATIVE SINGLE DIGITS IN THE LOWEST LYING
AREAS...TO THE TEENS (OR HIGHER?) WHERE STRATUS COMES BACK.

&&

.SHORT TERM...(SATURDAY THROUGH SUNDAY NIGHT)
ISSUED AT 240 AM EST FRI DEC 19 2014

HIGH IMPACT WEATHER POTENTIAL: NOTHING WIDESPREAD. A TOUCH OF
FREEZING DRIZZLE IS POSSIBLE SATURDAY NIGHT BUT CONFIDENCE IS VERY
LOW...LOW ENOUGH TO PRECLUDE ANY MENTION.

AN OVERALL QUITE BENIGN FORECAST FOR LATE DECEMBER AS WE PUSH
THROUGH THE WEEKEND - CERTAINLY SOMETHING THAT CAN`T OFTEN BE SAID
AROUND THESE PARTS APPROACHING THE CHRISTMAS HOLIDAY. THE BASIC
UPPER PATTERN LOOKS AWFULLY SIMILAR TO THAT SEEN FOR SOME TIME OVER
THE PAST FEW WEEKS...WITH AN OVERALL PACIFIC-DOMINATED FLAVOR TO THE
FLOW REGIME BUT A FEW WEAKISH/WIGGLY TROUGHS THROWN IN FOR FUN.
AFTER ALL...IT IS WINTER TIME. ONE OF THOSE SUCH FEATURES IS PROGGED
TO RESIDE ACROSS THE GREAT LAKES THROUGH MUCH OF THE WEEKEND...BUT
WITH CERTAINLY NO MAJOR COLD AIR INTACT...AS ALL OF THAT REMAINS
BOTTLED UP ON THE OTHER SIDE OF THE GLOBE. AT THE SURFACE...FAIRLY
ROBUST AND ELONGATED LOW LEVEL RIDGING WILL ENCOMPASS MUCH OF
SOUTHEAST CANADA THROUGH THE WEEKEND...WITH SAID RIDGING EXTENDING
BACK SOUTHWESTWARD THROUGH THE GREAT LAKES/OHIO VALLEY ON
SATURDAY...STEADILY MARCHING EASTWARD FOR SUNDAY AS DEEPER UPPER
TROUGHING BEGINS TO TAKE SHAPE OVER THE NORTHERN PLAINS.

FROM A SENSIBLE WEATHER PERSPECTIVE...THE MAIN CHALLENGE WILL BE
CLOUD EVOLUTION...AS OUR LOW LEVEL FLOW GOES FROM BEING VERY WEAK
SATURDAY MORNING TO STRENGTHENING SOUTH/SOUTHWESTERLY RETURN FLOW
INTO SATURDAY NIGHT AND SUNDAY. SATELLITE PICS OVER THE PAST FEW
DAYS ARE QUITE TELLING ALL THROUGHOUT THE REGION...WITH WIDESPREAD
LOW STRATUS PREVALENT ALL THE WAY BACK THROUGH THE PLAINS STATES AND
DOWN INTO THE SOUTHEAST CONUS AS WELL. THAT SETUP IS OF COURSE
COURTESY OF STUCK MOISTURE BENEATH A VERY SHARP/SHALLOW INVERSION -
TRULY A HALLMARK OF PACIFIC DOMINATED FLOW OVER THE LOWER 48. DON`T
SEE ANY BIG CHANGES OVER THE COMING FEW DAYS...WITH EXPECTED
DEVELOPING RETURN FLOW BASICALLY GRABBING A HOLD OF EXISTING
STRATUS AND HELPING LIFT IT BACK NORTHWARD INTO SATURDAY AND
ESPECIALLY SATURDAY NIGHT...WITH SOME MARGINAL LAKE INSTABILITY
ALSO HELPING THE PROCESS. EASTWARD EXTENT OF LOWER STRATUS INTO
NORTHEAST LOWER MAY BE HELD IN CHECK THROUGH MUCH OF SATURDAY AS
WE FIGHT THE WELL- ENTRENCHED WEDGE OF LOWER LEVEL DRY AIR...BUT
THINK ALL AREAS SHOULD BE RETURNED TO A CLOUDY SCENARIO BY LATER
SATURDAY NIGHT AND MOST DEFINITELY BY SUNDAY.

WEAKISH LOW LEVEL THERMAL/MOISTURE ADVECTION COMBINED WITH SOME LAKE
PROCESSES COULD AT LEAST PROVIDE A SMALL SHOT AT SOME FREEZING
DRIZZLE FOR SATURDAY NIGHT AS THE CLOUD DECK REMAINS WARMER THAN -6C
AND LIGHT SOUTH/SOUTHWESTERLY FLOW BUMPS UP AGAINST THE HIGHER
TERRAIN AREAS. HOWEVER...GIVEN THE VERY THIN NATURE OF THE
CLOUDS...GENERALLY HELD BELOW 925MB...CONFIDENCE IS MORE THAN LOW
ENOUGH TO PRECLUDE ANY MENTION.

OTHERWISE...OUR NEXT SHOT AT SOME LIGHT PRECIP SHOULD HOLD OFF UNTIL
LATER SUNDAY WITH THE NORTHEASTWARD EJECTION OF A WEAK SHORTWAVE
FROM MISSOURI INTO THE NORTHERN LAKES. BURGEONING AXIS OF DEEPER
LAYER WARM ADVECTION ASCENT SHOULD ACCOMPANY THIS FEATURE...
MAXIMIZED ACROSS NORTHERN WI AND THE WESTERN U.P. IN THE PROXIMITY
OF ENHANCED UPPER SUPPORT AS WELL...WHILE NORTHERN MICHIGAN FIGHTS
ENTRAINED DRYNESS ABOVE 800MB FOR QUITE A WHILE. THAT`S NOT TO SAY
WE WON`T GET INTO A BRIEF PERIOD OF SOME LIGHT SNOW (THAT`S MOST
LIKELY INTO THE TIP OF THE MITT AND EASTERN U.P. COUNTIES) BUT NOT
LOOKING LIKE A BIG DEAL AT ALL FOR MUCH OF THE AREA...WITH ANY
ACCUMULATION UNDER AN INCH...HELD IN CHECK BY BOTH WEAKER FORCING
AND WARM THERMAL PROFILES.

&&

.LONG TERM...(SUNDAY NIGHT THROUGH THURSDAY)
ISSUED AT 310 PM EST THU DEC 18 2014

HIGH IMPACT WEATHER POTENTIAL:  SIGNIFICANT STORM POSSIBLE TUESDAY-
THURSDAY.

LOTS OF ATTENTION ALREADY BEING PAID TO THE TRAVEL PERIOD AROUND
CHRISTMAS DAY WITH BROAD AGREEMENT OVER THE PAST FEW DAYS OF A
SIGNIFICANT STORM SYSTEM OVER THE NORTHEASTERN QUARTER OF THE
COUNTRY.  THE BEST AGREEMENT IN PROBABILISTIC GUIDANCE COMES WITH
DEVELOPING PRIMARY LOW AS CENTRAL NOAM TROUGH DIGS ON MONDAY-TUESDAY
WITH THIS SURFACE LOW MOVING GENERALLY IN THE DIRECTION OF THE GREAT
LAKES REGION.  MUCH LESS AGREEMENT SURROUNDS THE DEVELOPMENT OF A
SECONDARY SYSTEM FOR WEDNESDAY-THURSDAY...WITH RECENT FORECAST
TRACKS RANGING FROM NEW ENGLAND...TO THE EASTERN LAKES...THE LATTER
OF THESE OF COURSE SUPPORTING A SIGNIFICANT SNOW/WIND EVENT.

ENSEMBLE SENSITIVITY ANALYSIS /FROM SUNY STONYBROOK CSTAR PROJECT/
POINTS TO DIFFERENCES IN THE WEEKEND AMPLIFICATION OF THE PATTERN IN
THE CPAC AS THE PRIMARY DRIVER OF DOWNSTREAM SPREAD IN THE GEFS WITH
REGARDS TO THIS SYSTEM...SO EXPECT THAT WE/LL HAVE SOME INCREASED
CLUSTERING/CONFIDENCE ONCE THIS AMPLIFICATION OCCURS.

RECENT TRENDS:  THE GUIDANCE ENVELOPE HAS SHIFTED AWAY FROM THE
MONSTER LOW OVER LAKE HURON THAT WAS QUITE WELL-AGREED UPON
YESTERDAY AT THIS TIME.  INSTEAD...THE TREND HAS BEEN TO HAVE TRIPLE-
POINT LOW DEVELOPMENT OVER EITHER THE OHIO VALLEY /GFS-GGEM/ OR
ALONG THE MID ATLANTIC COAST /ECMWF/ TO RIDE NORTH...STRENGTHENING
RAPIDLY OVER THE EASTERN GREAT LAKES REGION. THIS DOESN/T SHED
MUCH NEW LIGHT ON THE HEAVY SNOW/NO HEAVY SNOW QUESTION...AND WITH
THE UNCERTAINTY MENTIONED ABOVE...WILL HAVE TO WAIT FOR MORE MODEL
CYCLES BEFORE SIGNIFICANTLY TRENDING FORECAST. LIKELY POPS
CERTAINLY WARRANTED FOR MUCH OF THE PERIOD.

AS MENTIONED IN THE SHORT TERM SECTION...THE ANTECEDENT AIRMASS WILL
NOT BE ALL THAT COLD...SO WITH A POTENTIAL SUB 1000 MB LOW WEST OF
LAKE MICHIGAN...HAVE SOME CONCERNS ABOUT PTYPE (RAIN OR
SNOW...LIKELY LITTLE-NO MIX) AS PRECIPITATION ARRIVES TUESDAY (WITH
MONDAY LOOKING QUIET AND SEASONABLY MILD).  EVEN WITHOUT SIGNIFICANT
SECONDARY DEVELOPMENT CLOSE TO THE GREAT LAKES REGION...A TRANSITION
TO LAKE ENHANCED SNOW SHOWERS LOOKS LIKELY FOR THE WEDNESDAY-
THURSDAY PERIOD...BUT WITH SOME QUESTION AS TO ROBUSTNESS OF THE
LAKE RESPONSE GIVEN LITTLE/NO ARCTIC AIR BEHIND THIS SYSTEM
/AT LEAST THROUGH THE END OF THE WEEK/.  SO...ACCUMULATING SNOW WITH
SOME TRAVEL IMPACTS IS LIKELY TO END THIS FORECAST PERIOD AND WILL
ADD THIS TO THE AFTERNOON HAZARDOUS WEATHER OUTLOOK. A WHITE
CHRISTMAS DOES APPEAR LIKELY FOR MUCH...IF NOT ALL OF THE CWA.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1244 AM EST FRI DEC 19 2014

...WATCHING THE MVFR STRATUS...

LIGHT NORTHERLY DRY AIR ADVECTION OUGHT TO KEEP THE LAST OF THE
STRATUS AWAY FROM MBL/TVC FOR THE REMAINDER OF THE NIGHT AND
TODAY. WINDS WILL BE CALM AT THE SFC TONIGHT...WITH AN EASTERLY
LAND BREEZE 3KTS AT MBL...BUT THE STRATUS LAYER FLOW THROUGH THE
NIGHT TURNS MORE SW. DEPENDING ON THE EXTENT/LOCATION AND OVERALL
EVOLUTION OF THE STRATUS...THE NW LOWER COAST...ESPECIALLY TVC/MBL
COULD SEE THE STRATUS WORK ITS WAY BACK INTO THE AIRPORTS. THIS IS
A DAUNTING TASK TO KNOW FOR SURE...SO WENT WITH A SCT MENTION FOR
NOW.


&&

.MARINE...
ISSUED AT 240 AM EST FRI DEC 19 2014

SFC HIGH PRESSURE TODAY...DRIFTS ACROSS THE REGION TONIGHT. A LIGHT
NORTHERLY FLOW BECOMES MORE CALM/VARIABLE LATER TODAY AND THIS
EVENING...THEN HAS A SLIGHT S/SW KICK TO IT ACROSS LAKE MICHIGAN
WHICH MAY DRAW IN SOME STRATUS. THIS LIGHT SW FLOW SPREADS OVER ALL
NEARSHORES SATURDAY NIGHT AND INTO SUNDAY...WITH STRATUS EVERYWHERE
BY MID DAY SUNDAY. NO PRECIPITATION THROUGH THE WEEKEND...WITH
CHANCES INCREASING MON...WITH LIKELY RAIN OR SNOWS TUE-WED.

ALSO...THERE IS POTENTIAL...BUT WITH LOTS OF UNCERTAINTY
INVOLVED...FOR A STRONG STORM SYSTEM IN THE WEDNESDAY TO CHRISTMAS
TIME FRAME. THIS IS A VERY EARLY LOOK...BUT GALE FORCE WINDS
(POSSIBLY STRONGER) ARE POSSIBLE.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&

$$

NEAR TERM...SMD
SHORT TERM...LAWRENCE
LONG TERM...ARNOTT
AVIATION...SMD
MARINE...SMD


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