Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 181756
AFDAPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
1256 PM EST THU DEC 18 2014

.UPDATE...
ISSUED AT 1036 AM EST THU DEC 18 2014

ON THE CURRENT SURFACE WEATHER MAP...1032 MB HIGH PRESSURE WAS
CENTERED ACROSS SOUTHWEST ONTARIO. VISIBLE SATELLITE IMAGERY AND
SURFACE OBSERVATIONS INDICATE THAT STRATUS DECK STILL COVERING
MUCH OF NORTHERN LOWER EXCEPT FOR THE TIP OF THE MITT. SO DESPITE
INCREASING RIDGING AT THE SURFACE AND ALOFT AND DRIER AIR
ADVECTING IN FROM THE NORTH...CLOUDS ARE EXPECTED TO BE SLOW TO
DISSIPATE ACROSS NORTHERN LOWER THIS AFTERNOON. THIS IS HANDLEDWELL
BY CURRENT FORECAST BUT WILL CONTINUE TO MONITOR TRENDS AND TWEAK
AS NECESSARY. MEANWHILE...IT WILL REMAIN MAINLY CLEAR ACROSS
EASTERN UPPER. WILL TRIM OFF A COUPLE OF DEGREES FROM HIGHS FOR
SOUTHEAST ZONES DUE TO THE THICK CLOUD COVER DOWN THAT WAY.

&&

.NEAR TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 212 AM EST THU DEC 18 2014

...SUNSHINE...

SYNOPTIC PATTERN AND OBSERVATIONS:

UPPER AND SFC LOWS ARE IN NEW ENGLAND EARLY THIS MORNING...WITH WEAK
FLOW/MID LEVEL RIDGING SLOWLY WORKING IN OVER NRN MICHIGAN. STRONG
COMPRESSIONAL WARMING/DRYING HAS ALREADY SCOURED OUT MUCH OF THE
MOISTURE THAT HAS BEEN LINGERING BACK ALONG RESIDUAL LOW TO MID
LEVEL TROUGHING. THIS SQUASHED THE SNOWS AROUND MIDNIGHT...AND ONLY
LEFT SOME WEAK/VERY LIGHT LAKE EFFECT IN NNW/NORTH FLOW REGIMES. WE
ARE EVEN SEEING THIS SNOW GET SEVERELY WEAKENED OVER THE LAST FEW
HOURS. THE STRONGEST PUSH OF THE DRIER AIR IS RIGHT INTO NRN
MICHIGAN...AND IS SEEN VIA LATEST SATELLITE...WITH CLEARING ALREADY
PUNCHING THROUGH EASTERN UPPER AND EVEN PARTS OF FAR NRN LOWER. THIS
IS IN CONTRAST TO WISCONSIN AND PARTS OF FAR WESTERN UPPER WHERE THE
STRATUS IS ACTUALLY EXPANDING WEST/NW OVERNIGHT. THE CLEARING SKIES
AND WEAKENING WINDS HAVE ALLOWED TEMPERATURES TO FALL INTO THE TEENS
ACROSS IN EASTERN UPPER.

SYNOPTIC PATTERN EVOLUTION AND ASSOCIATED WEATHER:

NOT MUCH TO TALK ABOUT. THE LOWER LEVEL TROUGHING/CONVERGENCE SLOWLY
DROPS SOUTH TODAY...WHILE MID LEVEL RIDGING AND STRONGER SFC HIGH
PRESSURE NEARS. LATEST SATELLITE AND DATA SUGGEST NOTHING TO STOP
THIS STRONGER PUSH OF DRYING AIR. THUS...SKIES WILL CLEAR THROUGH
THE DAY. THIS WILL TAKE LONGEST IN THE NORTHERLY FLOW REGIMES WHERE
CONTINUED OVERLAKE INSTABILITY HELP FEED OFF THE LAKES. THAT
SAID...WEAKENING WINDS THROUGH THE DAY WILL CONTINUALLY MINIMIZE ANY
MOISTURE FLUX OFF THE WATER. CLEAR SKIES FOR THE NIGHT...WITH EVEN
THE NORTHERLY FLOW REGIMES SEEING MOSTLY CLEAR CONDITIONS. THE LIGHT
WINDS AND CLEAR SKIES WILL ALLOW TEMPERATURES TO FALL INTO THE
SINGLE DIGITS TO TEENS ACROSS PRETTY MUCH ALL OF NRN MICHIGAN.

&&

.SHORT TERM...(FRIDAY THROUGH SATURDAY NIGHT)
ISSUED AT 246 AM EST THU DEC 18 2014

HIGH IMPACT WEATHER POTENTIAL: NONE

FORECAST CHALLENGES: CLOUD COVER.

OVERVIEW(ANALYSIS AND FORECAST)...SEMI-BLOCKY PATTERN AT 500 MB WITH
THE HIGH OVER THE MIDWEST AND NORTHWEST ONTARIO, AND THE LOWS OVER
THE NORTHERN PLAINS AND NEW ENGLAND. AT THE SFC HIGH PRESSURE IS
OVER THE REGION. THIS BLOCKY PATTERN WILL SLOWLY MOVE TO THE EAST
AND MOVE OVER MICHIGAN THROUGH THE EARLY PART OF THE WEEKEND
(SATURDAY) AND WILL BEGIN TO MOVE EAST OF THE UPPER GREAT LAKES BY
THE END OF THE WEEKEND (SUNDAY).

(12/19)FRIDAY...THE SFC HIGH MOVES OVER THE FORECAST AREA, AND THE
DRY AIR AT 850 MB AND IN THE 700-500 MB LAYER (RH<30% IN BOTH), WILL
EXPECT THAT THERE WILL BE MOSTLY SUNNY SKIES. HOWEVER, THE CAVEAT
HAS BEEN THAT THE MODELS KEEP FLIP-FLOPPING OF MOISTURE TRAPPED
BENEATH THE INVERSION. AT THIS POINT, THE MODELS (GFS, ECMWF, NAM)
ARE ALL SHOWING DRYING IN THE BOUNDARY LAYER, SO WILL HAVE TO SEE IF
THIS HAPPENS. WILL BE OPTIMISTIC WITH THIS. OVERNIGHT MAY BE
PROBLEMATIC, IF THERE IS ANY MOISTURE, WE COULD HAVE ISSUES WITH LOW
STRATUS/FOG IF THERE IS ANY MOISTURE TRAPPED BENEATH THE NOCTURNAL
INVERSION THAT WILL PROBABLY FORM UNDER THE LIGHT WINDS AND INITIALLY
CLEAR SKIES. HOWEVER, WILL CONTINUE THE OPTIMISM.

(12/20)SATURDAY...LOOKS TO BE A CONTINUATION OF WHATEVER HAPPENS
FRIDAY NIGHT AS THE LIGHT FLOW WILL PROBABLY BE TOO WEAK TO SCOUR
ANYTHING OUT THAT DOES FORM FRIDAY NIGHT. OF COURSE IF IT IS MORE
OPTIMISTIC WITH THE MAINLY CLEAR SKIES OVERNIGHT, THEN THE DAY WILL
BE PARTLY TO MOSTLY SUNNY IN THE MORNING WITH HIGH CLOUDS MOVING
INTO THE FORECAST AREA BY THE AFTERNOON. LOWER CLOUDS MOVE INTO THE
REGION OVERNIGHT AS THE NEXT SYSTEM MOVES OUT OF THE PLAINS AND INTO
THE UPPER GREAT LAKES.

&&

.LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 407 PM EST WED DEC 17 2014

SATURDAY NIGHT THROUGH SUNDAY: FAIRLY QUIET DURING THIS PERIOD AS
HIGH PRESSURE GRADUALLY PUSHES TOWARD THE EAST COAST.

SUNDAY NIGHT THROUGH WEDNESDAY: GOOD AGREEMENT THAT A WEAK WAVE OF
LOW PRESSURE WILL BEGIN TO DIVE SOUTHEASTWARD OUT OF
CANADA...BECOMING CENTERED OVER THE DAKOTAS SUNDAY NIGHT. AS THIS
FEATURE DOES SO...THERE IS A SLIGHT CHANCE WE SEE A SHOT OF LIGHT
WARM AIR ADVECTION SNOW LATE SUNDAY NIGHT INTO EARLY MONDAY MORNING
OVER THE NORTHWESTERN THIRD OF THE CWA...BUT NOT MUCH EXPECTED IN
THE WAY OF IMPACTS AS SNOW AMOUNTS WOULD REMAIN MINOR.

MORE IMPRESSIVELY DURING THE DAY ON MONDAY...A 160-180 KT PACIFIC JET
BEGINS TO DIVE FROM THE PACIFIC NORTHWEST INTO THE CENTRAL
ROCKIES...AIDING IN DIGGING AN IMPRESSIVE TROUGH INTO THE SOUTHERN
CONUS BY TUESDAY MORNING. AS ENERGY ROUNDS THE BASE OF THE TROUGH
TUESDAY NIGHT...THE TROUGH BECOMES NEGATIVELY TILTED BY WEDNESDAY
MORNING AND CONTINUES TO STRENGTHEN AS REFLECTED BY THE DEEPENING
~970 MB SURFACE LOW MOVING FROM THE OHIO VALLEY INTO THE THUMB/FAR
SOUTHERN ONTARIO DURING THE DAY ON WEDNESDAY.

IN TERMS OF LOCAL IMPACTS...THERE IS FAIRLY DECENT AGREEMENT THAT
DESPITE TIMING DIFFERENCES IN TERMS OF THE PRECIP ARRIVAL THAT 850
MB TEMPERATURES WILL REMAIN BELOW 0C FOR MUCH OF THE EVENT.
HOWEVER...PRECIP COULD FALL AS RAIN FOR A PORTION OF THE EVENT AS
925 MB AND SFC TEMPS REMAIN ABOVE FREEZING BEFORE THE LOW PUSHES
NORTH WELL INTO CANADA ALLOWING FOR COLD AIR TO SURGE INTO THE AREA.
THIS PUSH OF COLD AIR MAY NOT OCCUR IN FULL FORCE UNTIL TOWARD THE
VERY TAIL END OF THE PERIOD & BEYOND. WITH THIS BEING SAID AND
FAIRLY GOOD MODEL CONSISTENCY OF A DEVELOPING SYSTEM OVER THE
EASTERN HALF OF THE CONUS...SMALL DEVIATIONS TO THE TRACK AND
OVERALL EVOLUTION OF THIS SYSTEM CAN AND WILL RESULT IN LARGE
CHANGES TO THE SENSIBLE WEATHER FELT ACROSS THE CWA. DEFINITELY
SOMETHING TO KEEP AN EYE ON AS WE HEAD INTO THE HOLIDAY TRAVEL
TIME FRAME.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1242 PM EST THU DEC 18 2014

CLEARING CONTINUES TO WORK ITS WAY DOWN FROM THE NORTH (PLN IN THE
CLEAR)...THOUGH CLOUDS ARE HAVING A HARDER TIME MOVING OUT OF
APN. CLEARING SHOULD REACH TVC AND MBL OVER THE NEXT HOUR OR TWO
FOLLOWED BY APN. AFTER THAT VFR CONDITIONS EXPECTED FOR THE
REMAINDER OF THE TAF PERIOD.

&&

.MARINE...
ISSUED AT 212 AM EST THU DEC 18 2014

BASED ON AREA OBSERVATIONS...ALL ADVISORY LEVEL GUSTS HAVE
ENDED...AND AS NORTHERLY WINDS WEAKEN THROUGH THE DAY WITH INCOMING
SFC HIGH PRESSURE...THERE WILL BE NO MARINE ISSUES. WINDS REMAIN
WELL BELOW ADVISORY LEVELS THROUGH THE WEEKEND...WITH ALSO NO
PRECIPITATION EXPECTED.


&&

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

$$

UPDATE...SULLIVAN
NEAR TERM...SMD
SHORT TERM...JSL
LONG TERM...GILLEN
AVIATION...SULLIVAN
MARINE...SMD



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