Area Forecast Discussion
Issued by NWS Gaylord, MI

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000
FXUS63 KAPX 291510
AFDAPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
1010 AM EST MON DEC 29 2014

.UPDATE...
ISSUED AT 1010 AM EST MON DEC 29 2014

LARGE EXPANSE OF HIGH PRESSURE IS NOSING OUT OF SW CANADA ACROSS
THE NRN PLAINS AND INTO THE GREAT LAKES THIS MORNING...ALONG WITH
SOME FAIRLY DRY AIR POISED TO SPREAD INTO THE REGION LATER
TODAY/TONIGHT. BUT MEANWHILE...LOCALIZED ANALYSIS REVEALS LAKE
AGGREGATE TROUGHING STRETCHING FROM E/SE LAKE SUPERIOR INTO NRN
LAKE HURON. 12Z APX SOUNDING AND GUIDANCE FORECASTS REVEALING A
MUCH COLDER PROFILE IN THE LOWER LEVELS WITH H8 TEMPS IN -16C TO
-20C DESCENDING INTO NRN MICHIGAN (-17C AT APX THIS MORNING) AND
INVERSION HEIGHT SITTING JUST ABOVE 850 MB. PLENTY ENOUGH
INSTABILITY AND CONVECTIVE DEPTH SLICING THROUGH THE DGZ TO GET
SOME BETTER LAKE EFFECT SNOWS GOING OVERNIGHT AND THIS MORNING
DESPITE THE LACK OF SYNOPTIC SUPPORT. THUS...HAVE HAD REPORTS OF
3 TO 4 INCHES OF FLUFFY LES IN NRN CHIPPEWA COUNTY OVERNIGHT.

TODAY/TONIGHT...SOME RESPECTABLE LAKE EFFECT SNOWS CONTINUE AT
THIS HOUR ACROSS CHIPPEWA COUNTY AND HAVE BECOME BETTER ORGANIZED
ACROSS NW LOWER MICHIGAN AS WELL...AS THAT COLDER AIR HAS BEEN
DESCENDING INTO THE REGION. BECAUSE OF THAT...HAVE INCREASED
POPS/SNOW AMOUNT FORECASTS FOR THE SNOW BELTS OF EASTERN UPPER AND
NW LOWER MICHIGAN TODAY. PER GUIDANCE FORECASTS...LOWER LEVELS
STILL EXPECTED TO DRY OUT THIS AFTERNOON AND ESPECIALLY THIS
EVENING WHICH SHOULD TEND TO WEAKEN ONGOING LAKE EFFECT.

THAT SAID...I REMAIN A BIT CONCERNED ABOUT EASTERN UPPER MICHIGAN
AS HIGH RESOLUTION GUIDANCE SUGGESTS A REDEVELOPMENT/STRENGTHENING
OF LAKE AGGREGATE TROUGHING ACROSS SE LAKE SUPERIOR INTO NRN LAKE
HURON TONIGHT. BEEFED UP LOW LEVEL CONVERGENCE...HIGHER INVERSION
HEIGHTS AND A FAVORABLE THERMAL PROFILE WITH CONVECTION CONTINUING
TO SLICE THROUGH THE DGZ MAY CONTINUE TO ADD UP FLUFFY ADVISORY
LEVEL SNOW ACCUMULATIONS THROUGH TUESDAY.

&&

.NEAR TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 258 AM EST MON DEC 29 2014

...MOSTLY LIGHT LAKE INDUCED SNOWS TO CONTINUE...

HIGH IMPACT WEATHER POTENTIAL: SIMPLY NOT MUCH. STILL LOOKING AT
SOME LIGHT SNOW ACCUMULATIONS...PARTICULARLY ACROSS THE EASTERN UPPER
SNOW BELTS.

PATTERN SYNOPSIS/ANTICIPATED EVOLUTION: MUCH ADVERTISED RETURN TO A
COLDER WEATHER PATTERN WELL UPON US...COURTESY OF AN INCREASINGLY
AMPLIFIED N AMERICA PATTERN FEATURING PROMINENT FAR EAST PACIFIC
RIDGING AND SUBSEQUENT BROAD TROUGHING LAYING OUT ACROSS MUCH OF THE
CONUS. WHILE INITIAL SURGE OF COLD AIR HAS BEEN SOMEWHAT
MUTED...MUCH MORE IMPRESSIVE SURGE OF MODIFIED ARCTIC AIR ABOUT
READY TO MAKE ITS PRESENCE FELT HEADING THROUGH THE MID WEEK PERIOD.
SIMPLE MAGNITUDE OF COOLING AND STILL WIDE OPEN GREAT LAKES
RESULTING IN RATHER WIDESPREAD LIGHT SNOW SHOWER AND FLURRIES...THE
INTENSITY OF WHICH HAS BEEN GREATLY REGULATED BY LIMITED SYNOPTIC
SUPPORT AND AN OVERALL DRY AIRMASS. DESPITE FURTHER COOLING...
OVERALL FLAVOR OF THE FORECAST CHANGES LITTLE IN THE COMING
DAYS...WITH PERSISTENT MOSTLY LIGHT LAKE SNOWS TARGETING THE
TRADITIONAL SNOW BELTS.

PRIMARY FORECAST CHALLENGES/CONCERNS: LAKE EFFECT SNOW
COVERAGE...LOCATION...AND AMOUNTS TODAY AND TONIGHT.

DETAILS: A RATHER PURE LAKE EFFECT PATTERN WILL PERSIST THROUGH
TONIGHT. SYNOPTIC SUPPORT WILL REMAIN MINIMAL...CONFIRMED BY
UPSTREAM SATELLITE/SURFACE ANALYSIS SHOWING PLENTY OF DRY AIR SET TO
ROTATE SOUTHEAST ACROSS THE LAKES.

LAKE SUPERIOR: MATURATION OF LAKE AGGREGATE TROUGHING AND SIMPLE 150+
MILE FETCH LENGTH WILL DEFINITELY HELP THE SNOW PRODUCING CAUSE FOR
THE SNOW BELTS OF EASTERN UPPER MICHIGAN. DESPITE DURATION OF LAKE
MODIFICATION...CONVECTIVE BOUNDARY LAYER DEPTH REMAINS
LIMITED...GENERALLY AT OR BELOW 5 KFT. WHILE INVERSION LEVEL
TEMPERATURES ACTUALLY BECOME TOO COLD FOR DENDRITIC FLAKE GROWTH
...ENTIRE CLOUD DEPTH AND WEAK OMEGA PROFILE DO NOT...SUGGESTING
REASONABLY HIGH SNOW/LIQUID RATIOS TO CONTINUE. FLOW PATTERN REMAINS
LARGELY ROCK-STEADY OUT OF THE WNW...WITH SNOW SHOWERS REMAINING
MOST PERSISTENT ALONG AND NORTH OF THE M-28 CORRIDOR. ALL
TOLD...COULD SEE ANOTHER 2 TO 5 INCHES IN THE FAMED SNOW BELTS OF
NORTHERN CHIPPEWA COUNTY (INCLUDING SAULT STE MARIE) BY SUNRISE
TUESDAY...WITH PERHAPS SOME LOCALLY HIGHER AMOUNTS POSSIBLE SIMPLY
DUE TO PERSISTENCE OF ACTIVITY.

LAKE MICHIGAN: MUCH OF THE THERMODYNAMIC/KINEMATIC PROFILES OFF
NORTHERN LAKE MICHIGAN JUST DOWNRIGHT HOSTILE THROUGH THE
PERIOD...WITH NO SOURCE OF FOCUSED LOW LEVEL CONVERGENCE TO OFFSET
SHORT FETCH LENGTH...NO LARGE SCALE MOISTURE CONTRIBUTION...AND A
CONVECTIVE BOUNDARY LAYER EXPECTED TO REMAIN SUB 4KFT. CLOUD BEARING
LAYER WITHIN THE DGZ AND SIMPLE MAGNITUDE OF WATER/AIR TEMPERATURE
DIFFERENCE SHOULD KEEP SOME VERY LIGHT ACTIVITY TARGETING THE WNW-NW
FLOW FAVORED AREAS. REALLY STARTING TO THINK THIS WILL ESSENTIALLY
BE A NON-EVENT FOR NORTHWEST LOWER...WITH WIDESPREAD
FLURRIES/INTERMITTENT VERY LIGHT SNOW SHOWERS BRINGING LITTLE IN THE
WAY OF ANY DECENT ACCUMULATION. WILL FURTHER LOWER ALREADY MINOR
INHERITED SNOWFALL AMOUNTS...THINKING THOSE AREAS TARGETED BY THE
MOST PERSISTENT SNOW SHOWERS WILL SEE LITTLE MORE THAN A DUSTING BY
TUESDAY MORNING.

AS ALWAYS IN SUCH CASES...CLOUD COVERAGE REMAINS A FORMIDABLE
CHALLENGE...ESPECIALLY AWAY FROM THE LAKE BELTS (SEE YESTERDAY`S
SURPRISE CLEARING DURING THE MORNING). STILL THINKING MORE CLOUDS
THAN SUN...WITH LAKE INDUCED MOISTURE HAVING A HARD TIME MIXING OUT
UNDER SUBSIDENCE INVERSION. AS FOR TEMPERATURES...EXPECT HIGHS TODAY
MOSTLY IN THE LOWER AND MIDDLE 20S...WITH LOWS TONIGHT GENERALLY IN
THE TEENS.

&&

.SHORT TERM...(TUESDAY THROUGH WEDNESDAY NIGHT)
ISSUED AT 258 AM EST MON DEC 29 2014

TUESDAY AND WEDNESDAY...STRONG SURFACE RIDGE AXIS OVER MICHIGAN AT
12Z TUESDAY WILL SLOWLY DROP SOUTH INTO THE OHIO VALLEY BY TUESDAY
NIGHT. AS THE SURFACE HIGH BUILDS FURTHER SOUTH INTO THE SE US...
BROAD UPPER LEVEL TROUGHING WILL DIG INTO THE GREAT LAKES REGION.
THIS PATTERN EVOLUTION WILL SERVE TO REINFORCE THE COLD AIRMASS
OVERHEAD...MAINTAINING 850 MB TEMPS A FEW DEGREES EITHER SIDE OF -20
C FOR TUESDAY AND WEDNESDAY. DESPITE ABUNDANT OVER-LAKE
INSTABILITY...LAKE SNOW ACCUMULATION POTENTIAL WILL BE LIMITED BY
RELATIVELY LOW INVERSION HEIGHTS OF 4-5 KFT AND VIRTUALLY NO
MOISTURE AVAILABLE ABOVE THE INVERSION FOR ENHANCEMENT. W/NW WINDS
TUESDAY WILL SHIFT TO THE WEST LATE TUESDAY NIGHT AND THEN TO THE
W/SW ON WEDNESDAY AHEAD OF A WAVE SWINGING THRU THE BASE OF THE
BROAD UPPER LEVEL TROUGH. THUS...THE TYPICAL SNOWBELT REGIONS OF ERN
UPR AND NW/N CENTRAL LWR MICHIGAN WILL CONTINUE TO BE TARGETED FOR
THE HIGHEST POPS AND GREATEST POTENTIAL OF ACCUMULATIONS. NEW SNOW
ACCUMULATIONS WILL CONTINUE TO BE LIGHT...EXPECTING AN INCH OR LESS
FOR EACH FORECAST PERIOD THRU WEDNESDAY. HIGH TEMPS BOTH TUESDAY AND
WEDNESDAY WILL ONLY WARM INTO THE TEENS...WITH LOW TEMPERATURES BOTH
NIGHTS IN THE SINGLE DIGITS ABOVE ZERO TO THE LOW TO MID TEENS.

&&

.LONG TERM...(THURSDAY THROUGH SUNDAY)
ISSUED AT 258 AM EST MON DEC 29 2014

BROAD UPPER LEVEL TROUGHING WILL REMAIN IN
PLACE ACROSS THE GREAT LAKES REGION LATE THIS WEEK AND THRU THE
WEEKEND. OVER-LAKE INSTABILITY WILL BE MORE THAN SUFFICIENT FOR
CONTINUED LAKE SNOW PRODUCTION...PERIODICALLY ENHANCED BY A SERIES
OF SHORT WAVES RIDING THRU THE BASE OF THE BROAD TROUGH. HIGH TEMPS
WILL BE MAINLY IN THE 20S THRU THIS TIME PERIOD...WITH OVERNIGHT
LOWS GENERALLY IN THE TEENS.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 603 AM EST MON DEC 29 2014

LOW VFR/HIGH MVFR CIGS WILL HOLD OVER THE REGION THRU TUESDAY
MORNING AS LIGHT LAKE EFFECT SNOW SHOWERS/FLURRIES CONTINUE TO
STREAM INTO FAR NRN AND NW LWR MICHIGAN. OVERALL VSBYS WILL REMAIN
VFR THRU THE PERIOD...BUT MAY BRIEFLY DROP TO MVFR WITHIN SOME
SNOW SHOWERS. WINDS WILL REMAIN FROM THE NW BELOW 10 KTS.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR LHZ347-
     348.

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

$$

UPDATE...ADAM
NEAR TERM...MSB
SHORT TERM...MLR
LONG TERM...MLR
AVIATION...MLR



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