Area Forecast Discussion
Issued by NWS Gaylord, MI

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000
FXUS63 KAPX 182337
AFDAPX

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

.NEAR TERM...(THIS EVENING THROUGH TONIGHT)
ISSUED AT 310 PM 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 CONTINUES TO EVER SO
SLOWLY ERODE FROM THE NORTH. HOWEVER...THE STRATUS HAS BEEN A BIT
MORE STUBBORN TO EXIT ACROSS NORTHEAST LOWER. THE CLEARING TREND IS
EXPECTED TO CONTINUE THROUGH THE REMAINDER OF THE AFTERNOON DUE TO
DRY AIR ADVECTION AT LOW LEVELS WITH MAINLY CLEAR SKIES ACROSS THE
ENTIRE FORECAST AREA THIS EVENING AND OVERNIGHT. SO WITH FAIRLY
LIGHT NORTHERLY WINDS...MOSTLY CLEAR SKIES AND FRESH SNOW COVER
TEMPERATURES SHOULD DROP OFF FAIRLY WELL. LOWS EXPECTED TO RANGE
FROM THE SINGLE DIGITS ABOVE ZERO NORTH TO THE TEENS NEAR THE LAKE
SHORES.

&&

.SHORT TERM...(FRIDAY THROUGH SUNDAY)
ISSUED AT 310 PM EST THU DEC 18 2014

HIGH IMPACT WEATHER POTENTIAL:  SOME FREEZING DRIZZLE/FOG POTENTIAL
BEGINNING SATURDAY AND CONTINUING THROUGH SUNDAY.  OTHERWISE...NIL.

PATTERN:  SURFACE HIGH PRESSURE RIDGE BEGINS THE PERIOD OVERHEAD
FRIDAY MOVING EAST TO A POSITION OVER NEW ENGLAND/EASTERN CANADA BY
LATE SUNDAY.  THUS A WARM ADVECTION SETUP DEVELOPS THROUGH THE
WEEKEND...WITH INCREASING LLEVEL MOISTURE IN THE PRESENCE OF THE
DEPARTING RIDGE.

PWATS ARE QUITE PALTRY /0.10-0.15"/ TO START THE PERIOD WITH DRY
AIRMASS SUGGESTING PLENTY OF SUN FOR FRIDAY BEFORE INCREASING
MOISTURE PORTENDS A STRATUS THREAT THROUGH THE WEEKEND.  AM WORRIED
THAT WE/RE LOOKING AT A SITUATION SOMEWHAT LIKE LAST WEEKEND WITH
MUCH MORE IN THE WAY OF CLOUDS THAN SUN. THROUGH SATURDAY...MOISTURE
IS TOO SHALLOW FOR ANYTHING BUT CLOUDINESS...BUT AS IT DEEPENS
SATURDAY NIGHT-SUNDAY...HAVE TO WORRY ABOUT PRECIPITATION POTENTIAL.
THERE IS SOME SUPPORT FOR ASCENT AT MID LEVELS WITH A SERIES OF WEAK
NORTHERN STREAM SHORTWAVES. CAN/T RULE OUT SOME DRIZZLE/FREEZING
DRIZZLE POTENTIAL BY SATURDAY NIGHT...BEFORE DEEPER MOISTURE ON
SUNDAY SUGGESTS THAT IF ANYTHING FALLS FROM THE SKY...IT WOULD
LIKELY TAKE THE FORM OF A FEW SNOW SHOWERS.  WILL INTRODUCE A CHANCE
FOR FREEZING DRIZZLE POTENTIAL OVER THE HIGH TERRAIN SATURDAY NIGHT
WITH A LOW SHSN CHANCE SATURDAY.

TEMPERATURES: ORIGINAL AIRMASS IS POLAR...NOT ARCTIC IN NATURE...SO
DESPITE WHAT WILL LIKELY BE A COLD MORNING FRIDAY /WITH CLEAR SKIES-
LIGHT WINDS/ AND PERHAPS SATURDAY AS THE CLOUDS ARRIVE...HIGH
TEMPERATURES SHOULD MAKE A RUN AT FREEZING OR A LITTLE HIGHER.

&&

.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 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 635 PM EST THU DEC 18 2014

VFR.

AREA OF MVFR CIGS NOW SITS JUST S AND E OF APN/TVC/MBL...HAVING
CLEARED OUT OF APN WITHIN THE PAST HOUR OR SO. IT SHOULD CONTINUE
TO SLOWLY MOVE SOUTHWARD...AS HIGH PRESSURE LOOMS ACROSS
WI/WESTERN UPPER MI/SUPERIOR. SKIES WILL BE MOSTLY CLEAR THRU THE
FORECAST. WINDS WILL BE LIGHT FROM THE NORTH.

&&

.MARINE...
ISSUED AT 310 PM EST THU DEC 18 2014

NORTHERLY WINDS WILL CONTINUE TO DIMINISH TONIGHT AS HIGH PRESSURE
BUILDS IN FROM THE NORTHWEST. THIS AREA OF HIGH PRESSURE WILL KEEP
WINDS BELOW ADVISORY LEVELS THROUGH THE WEEKEND WITH NO
PRECIPITATION EXPECTED.


&&

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

$$

NEAR TERM...SULLIVAN
SHORT TERM...ARNOTT
LONG TERM...ARNOTT
AVIATION...JAZ
MARINE...SULLIVAN



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