Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 171911
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
211 PM EST Sat Nov 17 2018

LATEST UPDATE...
Synopsis/Discussion/Marine/Hydro

.SYNOPSIS...
Issued at 211 PM EST Sat Nov 17 2018

No major changes were made to the forecast, but the most potentially-
impactful/interesting elements are as follows:

- A light rain/snow mix may continue south of I-94 through early
Sunday morning with minimal impacts expected
- Two clipper systems will impact Lower Michigan late Monday night
through Wednesday morning, though Thanksgiving travel impacts appear
unlikely at this time.
- Warmer temperatures are expected Friday and Saturday with rain
  chances increasing during the latter.

&&

.DISCUSSION...(This evening through next Saturday)
Issued at 211 PM EST Sat Nov 17 2018

Radar returns associated with light snow have been fading quickly
this afternoon as the low-level lift (what little there was) scoots
south of I-94. Looking north, a few light lake effect snow
showers/flurries that developed in a Lake-Superior modified airmass
over Lake Michigan continue to drift over areas mainly north of US-
10. All in all, not much in the way of impactful weather is
happening today across Lower Michigan which is a welcome change
after an active week.

Forecast model guidance suggests that weak frontogenetical forcing
will persist on and off this afternoon through early Sunday morning
south of I-94, leading to a continuation of low-end PoPs for periods
of non-impactful light snow of flurries (though light rain may mix
with snow this afternoon given both dry and dew point temperatures
have warmed above the 32 degree mark). The lake-effect snow showers
up north will fade this evening but there is a signal that western
portions of Mason and Oceana counties may pick up a dusting
overnight under more persistent showers.

Attention will then turn to two clipper systems expected to bring
periods of light snow to Lower Michigan early next week/before
Thanksgiving. The first system will pass through Monday night and
into Tuesday with the second on its heels Tuesday night and into
Wednesday morning. Both have the potential to drop a quick dusting
to half inch of snow north of I-96 with perhaps a few inches north
of US-10. At this point, the daylight hours of both Tuesday and
Wednesday look to be dry but those planning to travel (especially
north) are strongly encouraged to stay up to date on the forecast as
it doesn`t take much snow to cause a travel headache.

The much anticipated "warm-up" is still on track but a bit later
than in previous forecasts. While Thanksgiving day will stay on the
cool side with highs in the mid 30s, the warmer temperatures will
arrive Friday and Saturday with highs in the mid to upper 40s (50
not out of question). Precipitation chances (liquid this time) will
increase Saturday as a rather deep but short-wavelength trough
swings through the Great lakes. It`s also worth noting that there
continues to be a strong signal that the clouds will break from mid-
afternoon Thanksgiving Day through mid afternoon Black
Friday...perfect to soak up the sun during an after-meal walk or
shopping outside.

Ensemble forecasts from both the GEFS and ECMWF suggests a typical
early-winter pattern will return to the Great Lakes for the end of
November with seasonable temperatures and periodic chances for
frozen precipitation.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1153 AM EST Sat Nov 17 2018

Light snow and associated IFR visibilities (1-3 miles) will end
from northwest to southeast this afternoon, with MKG/GRR/LAN
starting off with 6 mile or greater visibility at the beginning of
the TAF period and AZO/BTL/JXN following by 21Z/4PM EST. Ceilings
will be slower to recover, with MKG/GRR/LAN reaching 3500 ft or
so by mid afternoon. At JXN/BTL/AZO, MVFR ceilings of 2000 ft or
so are expected to persist through much of the TAF period with
very light rain and snow (e.g. no expected visibility
restrictions) continuing on and off through as late as 12Z/7AM EST
Sunday. Toward the very end of the TAF period, ceilings will rise
considerably to VFR/15000 ft or above from northwest to
southeast. Winds will be light (at or below 5 knots) through the
entire TAF period starting northerly this afternoon, becoming
variable during the overnight hours, and turning westerly Sunday
morning.

Light to moderate aircraft icing will be possible within a layer
from 3000 to 9000 ft at all TAF sites (but possibly as high as
13000 ft at AZO/BTl/JXN) through the entire TAF period.

&&

.MARINE...
Issued at 211 PM EST Sat Nov 17 2018

Winds and waves will be relatively calm through the weekend and
early next week.  Tuesday night and Wednesday, winds and waves will
increase leading to hazardous conditions to small crafts.  After a
brief reprieve Thursday, conditions will once again become hazardous
by late week.

&&

.HYDROLOGY...
Issued at 211 PM EST Sat Nov 17 2018

There are no hydrologic concerns through the next week as episodes
of rain and snow look light.

The threat for ice jams remains near zero through the next week as
daily average temperatures remain above 20 degrees. Warmer weather
is expected towards the end of next week.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...None.
&&

$$

SYNOPSIS...Borchardt
DISCUSSION...Borchardt
AVIATION...Borchardt
HYDROLOGY...HLO
MARINE...Borchardt


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