Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Gaylord Michigan
618 PM EST Wednesday Dec 24 2014

Near term...(this evening through tonight)
issued at 400 PM EST Wednesday Dec 24 2014

At 2 PM...994 mb low pressure was centered somewhere in the vicinity
of Findlay Ohio and Detroit. Apx and surrounding radars showed
pockets of higher reflectivities stretching from northern parts of
Indiana and Ohio into northern Michigan. The area of low pressure
will continue to track northeast across Eastern Lake Huron later
this evening. This track which is much farther east than model
guidance over the last several days (plus a little faster) will
likely keep the highest quantitative precipitation forecast just off to our east. Plus precipitation
will take its time changing over to all snow in most cases (except
for over the interior where this has already occurred)...not to
mention that the precipitation is taking a while getting its act
together. This all leads to an overall lowering of snowfall
accumulations...generally 1 to perhaps 3 inches across eastern upper
and the Lake Michigan shoreline counties...3 to maybe 5 inches
across the higher terrain of northwest lower and 2 to possibly 4
inches near the Lake Huron shoreline. Current advisories will remain
posted due to the wet and heavy nature of the snow in combination
with the fact that there are a lot of Holiday travelers out there
(plus I do not want to downplay this too much because roads will
likely still become slippery in some areas). Temperatures only
dropping off into the upper 20s and lower 30s for lows.


Short term...(thursday through saturday)
issued at 400 PM EST Wednesday Dec 24 2014

..periodic precipitation chances for the Holiday weekend...

High impact weather potential: some patchy freezing drizzle
Thursday morning especially higher terrain. Some light
accumulations of snow expected eastern upper/far northern lower
Friday night into Saturday.

Pattern synopsis/forecast: Pacific dominant split flow across North
America this Christmas evening...with all eyes on southern branch short
wave trough moving through the Mississippi Valley. Additional short
wave energy was moving onshore along the West Coast...with a strong
Pacific jet extending from Japan east across the date line. Surface
analysis shows a north-south oriented front ahead of the Mississippi
Valley short wave trough with low pressure organizing along it over
the Ohio Valley. Coldest air was stuck up across the Canadian high
latitudes. Surge of deep layer moisture along the front...
precipitable water values 200-300+ percent of normal from the
eastern Gulf all the way to the upper Great Lakes.

Tonight's system expected to be over the lower lakes at the start of
the short term portion of the forecast Christmas morning...while
eastern Pacific short wave energy moves into the Great Basin. This
in turn will push a low amplitude short wave ridge into the
Midwest/Great Lakes...with broad anticyclonic flow aloft expected
for Friday. Heading into the weekend...forecast concern will be
focused on western trough and possibility of some short wave energy
getting kicked northeast. But a slower trend is preferred which
will keep the bulk of the troughing well west of the area through
Saturday. Height falls moving into the west will push a cold front
into the Midwest Thursday night/Friday...then across Michigan Friday

Primary forecast concerns: tonight's snowfall should be done by
Christmas morning...potential for a middle level deformation/
frontogenetic snow band to set up across northern portions of the
forecast area for Christmas night. Friday looks quiet...then with
middle level troughing pushing into the Midwest Saturday may be looking
at another round of snow or possibly some mixed precipitation to
start the weekend.

Christmas day (thursday) through Saturday...synoptic precipitation
expected to be done by Thursday morning...still plenty of clouds
around upstream so anticipating an overcast day overall. Can't rule
out the possibility of patchy drizzle/freezing drizzle especially
during the morning with a moist boundary layer with steeper lapse
rates...favored across upslope areas. Christmas afternoon
temperatures expected to be 5-10 degrees above average for the
Holiday...with highs middle-upper 30s expected. Chance for more
synoptically driven precipitation heading into Thursday night along
an east-west axis that will right now looks to impact eastern upper
and far northern lower...not looking like a huge deal at this point
and will probably be pretty modest with probability of precipitation.

Friday looks mainly cloudy at this point but precipitation chances
look pretty minimal...temperatures once again expected to be in the
30s. Weak cold front likely to push east into northern Michigan
Friday night...ahead of middle level short wave troughing moving into
the Midwest. Deeper moisture/forcing spreading in from the west may
be enough to push some precipitation into the forecast area during
the pre-dawn hours of Saturday...mostly in the form of snow but
there is some uncertainty along the southern edge about the
possibility of a mix or rain.

Better threat for precipitation will be forcing
strengthens and some potential for decent low level frontogenetic
forcing...likely probabilities seem reasonable across all of
northern Michigan. Precipitation type issues will come into play
along/south of M-72 though exact rain/snow line is in flux. Will
plan for more snow across eastern upper and far northern lower with
an inch or so accumulation to start.


Long term...(saturday night through wednesday)
issued at 400 PM EST Wednesday Dec 24 2014

Pattern looks to remain active with some weaker disturbances coming
through the region behind the larger Christmas time system. This
will result in chances for snow throughout the extended
period...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 as colder air moves in.
Temperatures will start near normal in the upper 20s and slowly cool
through the period with below normal highs in the upper teens and
low 20s to ring in the New Year. Lows will follow suit starting the
period above normal in the low 20s cooling to single digits by the
end of the period.


Aviation...(for the 00z tafs through 00z Thursday evening)
issued at 617 PM EST Wednesday Dec 24 2014

Widespread mix of rain and snow will change to all snow this
evening...and then diminish to freezing drizzle overnight as low
pressure tracks NE away from Michigan. IFR condition will
gradually improve to MVFR tonight. Mainly dry weather and MVFR
ceilings are expected for Christmas day. Northwest winds will strengthen to
15 to 25 kts tonight and shift to the west/SW for Christmas day.


Apx watches/warnings/advisories...
Michigan...Winter Weather Advisory until 7 am EST Thursday for miz016>019-

Winter Weather Advisory until 7 am EST Thursday for miz024-030-

LH...Small Craft Advisory until 5 PM EST Thursday for lhz345-346-349.

Gale Warning until 11 am EST Thursday for lhz347-348.

Lm...Small Craft Advisory until 5 PM EST Thursday for lmz323-341-342-

Ls...Small Craft Advisory until 5 PM EST Thursday for lsz321-322.



Near term...Sullivan
short term...jpb
long term...alm

National Weather Service Glossary of Abbreviations