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Area forecast discussion 
National Weather Service Grand Rapids Michigan
656 am EST Thursday Nov 26 2015

Latest update...

issued at 326 am EST Thursday Nov 26 2015

A rainy Thanksgiving day is expected as showers continue to develop
along a cold front that is slowly moving toward lower Michigan.
Showers will continue into Friday before ending late in the day as
mixed light rain and snow showers. Temperatures will cool into the
middle 30s by Saturday before warming into the 40s Sunday.


Short term...(today through saturday)
issued at 326 am EST Thursday Nov 26 2015

Forecast concerns deal with precipitation chances through Friday.

Regional radar shows showers continuing to move northeast from the
Missouri Valley into lower Michigan. A 40-50kt low level jet is drawing
moisture northward from the Gulf of Mexico where it's interacting with the
slow moving frontal boundary that stretches from Western Lake
Superior southwest to northwest Missouri. Good convergence along the
boundary is resulting in steady shower development. Short range
models show a couple of waves moving north along the boundary which
will tend to slow the eastward progression a bit. As a result we/re
looking at around 24-30 hours of rain showers. Rainfall accumulation
will be heaviest northwest of a Muskegon to Baldwin line with over
an inch possible. The least amount will be over the far southeast
around Jackson with around a half inch. The cold front will pass
across the County Warning Area Friday morning. As colder air flow south behind
it...lingering precipitation will turn to mixed rain/snow showers. This isn't
a strong shot of cold air however and snowfall accumulations are not

Saturday and Sunday look dry as high pressure over Iowa/Minnesota
builds into lower Michigan.

Long term...(saturday night through wednesday)
issued at 326 am EST Thursday Nov 26 2015

Continued to follow the European model (ecmwf) tonight as it has remained consistent
through the long term period. Each model run of the GFS seems to
trend more toward the European model (ecmwf) in regard to the more significant
features. The Canadian is close to the European model (ecmwf) in evolution of the
pattern. The GFS while not far off in regard to mass fields lags
just a bit as it plays catch up.

The main weather feature of note in the long term is the upper low
which is currently located over the Great Basin in the west. In the
beginning of the long term...over the weekend...the low moves into
the plains. It is not until early next week that this system moves
into the Great Lakes and brings US sensible weather. So...have a dry
forecast Saturday night into Monday morning with seasonable

On Monday brought rain showers in during the afternoon. Feel this
may be a tad early...but it is collaborated with neighboring
offices. The best chance for precipitation with this system is
Monday night into Tuesday as the upper low moves overhead. Rain
showers Monday night will mix with and change over to snow Tuesday
afternoon and Tuesday night. Precipitation does not look to be heavy
with the system. We could see a period of lake effect snow Tuesday
night into Wednesday as some deeper moisture swings through our
area. At this point though nothing that looks too significant.

Bottom line...a quiet weekend followed by a more active weather
pattern early next week. Temperatures will be seasonable.


Aviation...(for the 12z tafs through 12z Friday morning)
issued at 655 am EST Thursday Nov 26 2015

Conditions range from VFR in the far south along I-94...with IFR
conditions already invading places like kmkg and kgrr. The general
thinking is conditions will gradually lower today from northwest
to southeast...which is the trend in the 12z tafs. A caveat though
is some of the forecast models are trying to lift the rainfall
northward today...drying US out a bit this afternoon. At this
point opted to continue the downward trend in aviation conditions
through the day with rain persisting.

Tonight...conditions should lower further with all areas becoming
IFR as the cold front the rain is associated with draws near from
the north.

It will be a windy 24 hour taf period as southerly winds today
gust into the 20-30 knot range. Tonight winds will shift around to
the west and northwest with time.

Bottom line...conditions trending into IFR at all taf sites over
the course of the next 24 hours.


issued at 326 am EST Thursday Nov 26 2015

Extended the Small Craft Advisory through Friday night based on wave heights at or above 3
feet. Gusty south winds will become northwesterly Friday and cold air
advection will cause waves to remain hazardous to small craft.


issued at 1150 am EST Wednesday Nov 25 2015

The focus continues to be on the anticipated rainfall late
tonight through addition to the snowmelt in the
hardest hit locations from saturdays snowfall.

Expectations for the upcoming rainfall have been fairly
consistent with a spread in totals...from about 0.75 inches in
the southeast (jackson) to around 1.50 inches in the northwest
(ludington). Though rainfall and snowmelt will cause within bank
rises on streams and rivers...the greatest potential for near or
above bankfull levels exists in the southeastern third of the County Warning Area.
Namely...the Maple River at Maple Rapids and Sycamore Creek at
Holt...are forecast to crest slightly above action state.

For now...the revise serving its purpose as some question still
lingers in the speed of the snowmelt and rate at which the rain
will fall. Some reports have reflected that about half the snow
depth has been consumed by melting in the last 24-48 hours. At
this rate...much of the feedback may gradually make into rivers
sparing any greater concern. It will continue to be monitored as
rainfall is realized through Friday.


GRR watches/warnings/advisories...
Lm...Small Craft Advisory until 6 am EST Saturday for lmz844>849.



short term...04
long term...Duke

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