Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 141833
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
133 PM EST Tue Feb 14 2017

LATEST UPDATE...
Hydro

.SYNOPSIS...
Issued at 328 AM EST Tue Feb 14 2017

A storm system tracking southeast through central Ontario today
will push a cold front through the area this evening. It will
be significantly warmer than normal today with may areas having
highs above 40 degrees. Expect rain showers later this afternoon
just ahead of the front. Those showers will change to light snow
showers behind the front this evening. Snow accumulations tonight
will limited at best. It will be colder tonight but still warmer
than normal, with lows mostly in the 20s. Light snow showers are
expected Wednesday and Wednesday night but accumulations will be
mostly an inch or less. highs will be near 30s. High pressure
moves through the area Thursday ending the snow showers. Highs
should be near freezing.

A strong warm front moves through the area Friday and that will
bring much warmer than normal temperatures through a good part of
next week. Highs will be in the 50s for the most part and lows
from the mid 30s to mid 40s. Rain showers are possible by early
next week.

&&

.UPDATE...
Issued at 1050 AM EST Tue Feb 14 2017

After coordination with APX to the north, will issue a winter
weather advisory (hopefully before 1 pm) valid overnight chiefly
for northern counties for what will likely be greatly reduced
visibilities in blowing snow of the fluffy lake effect variety.
Although accumulations shouldn`t be great, they could be enough to
aid in icing of roads as temperatures fall into the lower to mid
20s overnight.

One of the major factors of this decision is the similarity to
what was experienced last weekend with its slightly more extreme
conditions. Last weekend`s analog has also been a factor in the
slight uptick in forecast snow amounts in general.

There is some question about how far south to extend the
advisory, because driving conditions could also be impacted by
temperatures dropping below freezing combined by the antecedent
precipitation this afternoon and evening advertised by some
convection allowing models.

&&

.SHORT TERM...(Today through Thursday)
Issued at 328 AM EST Tue Feb 14 2017

We are tracking the potential for showers ahead and with the cold
front late this afternoon and evening then snow showers and
flurries tonight through Wednesday night.

As with yesterday, there is typically deeper mixing ahead of a
cold front, today will be no different. That will allow it to
warm into the lower to mid 40s over the central and southern parts
of our forecast area. Nearly all of our high res models show a
band of showers with the cold front this evening. Given the
strength of the upper wave diving south and that we have the exit
region of a 135 knot jet core to help the cause in thinking most
areas will see the showers this evening.

Wednesday we are in the deep cold air with cyclonicly curved low
level winds and inversion heights on the GFS are near 6000 ft.
The lake is around 2c while 850 temps fall to near -15c so the air
will be cold enough for lake enhanced snow showers. All of our
models area forecasting some QPF and it has been my experience
when they do that it will snow. This is also supported by the CIPS
analogs and NCAR ensembles with have 60 to 70 pct 1 hour pops
over most of our CWA Wednesday. As I wrote yesterday, this will
not be a big snow event but THERE WILL BE SNOW SHOWERS west of
US-131 most of the day Wednesday.

The jet core moves east of the CWA Thursday morning so that will
end the snow showers but the surface warm front does not get
through the area till Friday morning so temperatures should for
the most part be below freezing from midnight tonight through
Friday morning.

My bottom line is warm today with showers this evening, colder
with snow showers Wednesday then partly cloudy and cold Thursday.

.LONG TERM...(Thursday night through Monday)
Issued at 328 AM EST Tue Feb 14 2017

We are looking potentially record breaking warmth for this coming
weekend and early next week, with mainly dry conditions expected
through the period.

The only chance of pcpn we have in the long term portion of the
forecast is right at the beginning on Thu. Lake effect expected mid-
week will be ending, and an elevated warm front will be pushing
through as the cold air will be moving out.

We still expect to see a progressive warm up from Fri right on
through next Mon. We will see a fairly amplified ridge slowly push
toward the area through Sat as troughing occurs out west. There are
indications that a short wave could beat the ridge down briefly and
try to push a cold front into the area. A westerly low level flow
may temper temperatures a little on Sat with flow off of the
cooler lake.

We look to see more warming take place then Sun and Mon with
temperatures pushing close to record levels in the lower 60s. The
upper ridge will be reinforced as additional energy dives in across
the Western U.S.. This warming will be assisted by the low level
flow becoming more srly and not off of the lake. The reinforcement of
the ridge should also keep pcpn from moving in across the area.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1225 PM EST Tue Feb 14 2017

Latest satellite imagery and surface observations show layer of
mid and high clouds spreading into Michigan this morning...with
lower clouds indicated across northern and central Michigan.
Expect lower clouds to spread/develop south as surface low moves
from western to southern Ontario this afternoon into tonight.

KMKG reported ceiling of 1800 ft AGL in the past hour. Initially
thought this would be a temporary concern...but ASOS data suggests
that it will persist this afternoon. Should see a slight increase
in ceiling height to around 2500 ft later this afternoon. Low
clouds also developing in the KGRR area...so will add the MVFR
ceiling there as well. Other TAF sites will not see lower ceilings
until later this afternoon.

Precipitation will spread from northwest to southeast later this
afternoon through the end of the forecast period. While rain
should be the primary type initially...expect a mix and then a
change to all snow this evening as colder air filters in.

A gusty west to northwest wind will also continue throughout the
period with the strongest gusts...near 30 kts...around 00z.

&&

.MARINE...
Issued at 328 AM EST Tue Feb 14 2017

After conferring with near by offices we decided to go with a
gale warning tonight. The models support the idea of gales with
the front as it passed through the area. At any one point, the
gales will last less than 3 hours but since it takes most of the
night to get the front south of the state I have the gale warning
all night.

&&

.HYDROLOGY...
Issued at 133 PM EST Tue Feb 14 2017

River levels continue above normal, but minor flooding has come to
an end. Little precipitation is expected through the week and
temperatures will be above normal, so river levels should fall into
next week.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Winter Weather Advisory from 7 PM this evening to 9 AM EST
     Wednesday for MIZ037>040-043>046-050>052-056>059-064>066-
     071>073.

LM...Small Craft Advisory until 7 PM EST this evening for LMZ844>849.

     Gale Warning from 7 PM this evening to 7 AM EST Wednesday for
     LMZ844>849.

&&

$$

UPDATE...TJT
SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM...JAM
AVIATION...MWS
HYDROLOGY...63
MARINE...WDM



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