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Area forecast discussion 
National Weather Service Grand Rapids Michigan
721 am EST Monday Nov 24 2014

Latest update...

issued at 330 am EST Monday Nov 24 2014

Rain ongoing early this morning will diminish a bit in coverage
and intensity this morning. Intervals of rain will continue
through middle afternoon across the area before all rain changes to
snow fairly rapidly late this afternoon into early this evening.
Snow will accumulate across the area from tonight through
Tuesday...with the highest amounts occurring to the northwest
toward Ludington.

We will see a break in the snow from late Tuesday night into
Wednesday before snow showers will become possible once again.
There will be at least a chance of snow for Thanksgiving and into
the weekend...however no significant snowfall is expected later
this week. A moderation in temperatures and precipitation changing
over to rain will be possible next weekend.


Short term...(today through Tuesday night)
issued at 330 am EST Monday Nov 24 2014

We have issued a Wind Advisory for this afternoon and early
evening for roughly the southeast half of the forecast area. A Winter Weather
Advisory has been issued for roughly the northwest half of the area for
late this afternoon through the day on Tuesday.

Steady rain continues to fall across the area early this morning
with the dry slot trying to make it into the forecast area from the
south. We are seeing the moderate rain that fell last evening shift
out of the area as the core of the low level jet ahead of the low shifts east
of the area. The dry slot should stay just south of the County warning forecast area
border...keeping periods of rain/showers moving through the area
today. The area of showers moving across southern Illinois as of 08z this
morning will be the last of the widespread rain for the area that
will move through late this morning and into the afternoon hours.

The winds are light right now across the area...but will increase
late this morning/early this afternoon across the southeast portion of the
County warning forecast area. The band of showers across southern Illinois is with a surface wave that will
move up into the area. Once this wave moves by...the cold air
advection will commence as the stronger gradient moves in. Models
indicate that 40 knots or so around 2k feet will be very able to be
mixed down with the good mixing due to the cold air advection.

We will see all rain change over to snow fairly quickly from SW to
NE after 21z and almost across the entire area toward 00z. We will
see the band of precipitation coming up ahead of the southern Illinois wave move north
and almost become stationary across the northwest half of the County warning forecast area. This
occurs initially with an initial deformation band from the upper
wave coming in from the SW. We will then see the next short wave
with the parent trough rotate in across the area and favor the northwest
counties once again. By this will be snowing and will

This snow will affect the northwest half of the County warning forecast area from this evening into
early Tuesday afternoon when a third short wave moves through in the
same fashion. We are looking at a prolonged light snow event with
some enhancement at times due to a SW flow off of the Lake. Delta
T/S will be in the teens and moisture will be quite deep over the
area. What will keep this from being a more significant event will
be an inversion that fluctuates from 5-8k feet. This will limit the
lake enhancement from becoming too strong...but some locally heavier
amounts will still be possible. Some upslope flow across the hills
of central lower could also help totals a bit. Some blowing and
drifting will be possible toward the Lakeshore where winds will be a
little stronger.

As the main upper trough finally pulls out Tuesday afternoon...we will
see snow showers diminish. There could be some decent bands move
through GRR Tuesday morning as the flow becomes more west-northwest before
everything ends late Tuesday. Amounts will be lower toward GRR...however
the Tuesday morning commute could be impacted.

Long term...(wednesday through sunday)
issued at 330 am EST Monday Nov 24 2014

Other than the possibility of some light lake effect snow
accumulations on Thanksgiving day... confidence is increasing that
minimal travel impacts will occur over the upcoming Holiday period.

Models have trended much farther south will the clipper low on
Wednesday and Wednesday night so the synoptic snow potential with
that system now looks quite low.

800 mb air around -15c is still prognosticated to come into the area via
northwest winds on Thanksgiving day. Conditions look favorable for
lake effect snow for about 12 hours as 500 mb shortwave pivots
through... so a few inches of accumulation still appears possible
near and west and Highway 131. Surface ridging and warm advection
arrives Thursday night and the lake effect should diminish at that

After Thanksgiving day... the upper flow GOES flat/zonal with 100 knots
Pacific jet shooting across the northern Continental U.S.. this pattern will lead to
milder temperatures developing across SW Michigan toward the end of the
week with only a small chance for light snow or mixed light rain and

Latest 00z guidance now shows a rather strong warm advection pattern
on Saturday ahead of a northern plains low... so we may need to boost
highs into the 40s if this trend remains. That same system drags a
cold front through on Saturday night or early Sunday as it moves
east... but not much quantitative precipitation forecast along the front and strong surface ridging
developing behind it on Sunday.


Aviation...(for the 12z tafs through 12z Tuesday morning)
issued at 720 am EST Monday Nov 24 2014

Widespread IFR conditions with rain showers continuing this
morning. Snow developing at mkg and GRR after 21z keeping
conditions IFR into tonight. Some improvement to MVFR possible
this afternoon/evening south and east of GRR. Cant rule out a
thunderstorm this afternoon south and east of GRR but was not confident
enough to put in the tafs.

Big increase in southwesterly winds expected this afternoon...
with gusts to 40 kts possible especially south and east of GRR.
Those winds are expected diminish later this evening but should
still continue to gust to 25 kts overnight.


issued at 430 am EST Monday Nov 24 2014

A significant increase in winds from the west southwest is
anticipated today as a deepening low pressure system moves
northeast through the Great Lakes region. Gales will develop south
of Pentwater later this morning and continue through this evening
before gradually diminishing late tonight as the low pulls away.
Waves will build to as high as 12 feet during the peak of the
event later today.


issued at 430 am EST Monday Nov 24 2014

Widespread rainfall amounts of 1.00 to 1.50 have already occurred
and up to another 0.50 is still possible today. Many of the smaller
tributaries such as the Macatawa river at Zeeland and plaster creek
in Grand Rapids have shown significant rises overnight due to the
rain... suggesting some impacts are possible this morning with
water over roads/parking lots in spots. Plenty of standing water
will be noticeable as well today in any low lying or poor drainage

On the larger rivers/tributaries... river flood advisories have
been issued for expected bankfull stages at the following
locations: the Looking Glass river at Eagle... Sycamore Creek at
Holt... the Flat River at Smyrna... and the Rogue River at

Based on the rainfall that has already fallen... additional river
advisories for bankfull stages will likely be needed later this
morning for at least the following locations: the pere Marquette at
Scottville... the White River at Whitehall... and Maple River at
Maple Rapids... the Thornapple at Hastings... and the Grand River at
Ionia. The response at these locations is more delayed than the
above locations... with bankfull stages probably not occurring
until 1-3 days from now.

No rivers are expected to reach their flood stages at this
point... but this will need to be closely monitored over the next
24 hours as rainfall has been a little more than expected with a
bit more to come... and all the snow pack has melted.


GRR watches/warnings/advisories...
Michigan...Wind Advisory until 10 PM EST this evening for miz052-058-059-

Winter Weather Advisory from 4 PM this afternoon to 4 PM EST
Tuesday for miz037>040-043>046-050-051-056-057.

Lm...Small Craft Advisory until 7 am EST Tuesday for lmz849.

Gale Warning until 7 am EST Tuesday for lmz844>848.



short term...njj
long term...Meade

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