Area Forecast Discussion
Issued by NWS Grand Rapids, MI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
612
FXUS63 KGRR 050444
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
1144 PM EST Sun Dec 4 2016

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 314 PM EST Sun Dec 4 2016

Light to, at times moderate, snow will continue through late
tonight. Generally 1 to 3 inches of accumulation is expected, but
areas west of US-131 could see 3-4 inches (on grass). Temperatures
in the low to mid 30s this afternoon and evening should keep roads
mostly wet, but slushy, slick conditions are very possible under
moderate snowfall rates and tonight as temperature gradually cool
slightly. Quiet weather is expected on Monday, before light rain
and snow chances return to the area on Tuesday.

A significant weather pattern shift will bring much colder air
into Lower Michigan Wednesday through Saturday. Lake-effect snow
is expected, and several inches of snow is likely across the
western forecast area. Highs in the upper 20s to around 30 will be
common late this week into the weekend, with lows in the teens to
lower 20s.

&&

.SHORT TERM...(This evening through Tuesday night)
Issued at 314 PM EST Sun Dec 4 2016

Snow has begun across most of Southwest Lower Michigan and will
continue before winding down from west to east between 10 pm and 1
am tonight. Upstream radar trends and snowfall reports have
boosted confidence in areas west of US-131 seeing 3-4 inches by
late tonight. The 1-3 inch forecast continues for areas further
east. As of 230 pm, radar indicates a few areas of moderate snow
along the lakeshore, including in Ludington and Holland. Moderate
snow was also noted in northeast Illinois. Roads may become slick
with slush late this afternoon and evening, particularly bridges
and overpasses.

Surface temperatures that were around 36-37 degrees at precip
onset have since wet-bulbed to 32-34 degrees in steady snowfall.
Temperatures in the low 30s will be common away from Lake Michigan
late tonight into Monday morning, with mid 30s readings right
along the lakeshore. The inland areas especially will likely see
some slick road conditions during the Monday morning commute.

Otherwise, Monday`s weather looks fairly quiet with mostly cloudy
skies. Highs will be in the upper 30s to low 40s.

Shortwave ridging builds into the western Great Lakes on Monday,
providing the tranquil weather. The ridge axis pushes east of
Lower Michigan Monday night and surface high pressure tracks from
West Virginia to New York. Precip chances return Tuesday, mainly
south of a South Haven to Lansing line. A deep upper low drops
into Northern Plains by Tuesday night, while a potent mid-level
wave occludes over Ontario. Meanwhile, a southern stream system
tracks from the Ohio Valley to the northeast. The northern extent
of southern stream deformation may bring some light precip to the
southern/southeastern CWA. The northern stream system pushes a
weak cold front through late Tuesday, but moisture is lacking.
Precip type is uncertain during this time frame for whatever light
precip does occur. Some light snow would be possible early
Tuesday, transitioning to a mix and then all rain in the
afternoon.

.LONG TERM...(Wednesday through Sunday)
Issued at 314 PM EST Sun Dec 4 2016

Forecast issues in the extended are mostly focused on coverage of
lake effect snow Wednesday night through Saturday as cold settles
in. Expect several inches of snow across the western zones in
generally west to northwest flow regime during that time frame.

Light snow should begin Wednesday evening as push of cold air
arrives, but the heavier snows should hold off until arctic front
moves through later Thursday into Friday. Inversion heights are
expected to be above the DGZ during this time and then begin to
lower later Friday as upper trough axis shifts east.

By Saturday, the lake effect snow showers will be decreasing but we
will have to watch a shortwave trough moving across the northern
Plains. This will have the potential for a sfc cyclone and some
synoptic snows by Saturday night into Sunday in warm air advection
pattern.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1130 PM EST Sun Dec 4 2016

A mix of mainly mvfr/ifr conditions will continue overnight due to
extensive low clouds and lingering light snow showers and
flurries. These conditions will linger Monday morning due to
lingering low cloud cover and possibly some patchy fog.

Conditions will then improve to vfr Monday afternoon as low clouds
move out and dissipate. Conditions will then remain vfr through
Monday evening.

&&

.MARINE...
Issued at 314 PM EST Sun Dec 4 2016

Waves will build to 2 to 4 feet late tonight as westerly winds
increase to 15 to 25 knots. 2 to 4 foot waves will persist into
Monday. These waves should gradually subside to 1 to 3 feet south
of Holland on Monday. North of Holland, marine conditions will
remain marginally hazardous for smaller craft through Monday
night.


&&

.HYDROLOGY...
Issued at 1219 PM EST Sun Dec 4 2016

The Maple River advisory at Maple Rapids continues with a bit of
question, due to the recent drop in river levels. Trends will need
to be monitored to reconsider this headline this evening. All of
this depends on total precipitation amounts, which are expected to
come in the form of snow today and should not exceed one-quarter
of an inch over south-central Lower Michigan.

Monday should be dry with light precipitation amounts through the
middle of the week. The later half of the week could introduce
another quarter inch or so of precipitation when lake effect snow
kicks in. Much of that should stay confined to locations along
and west of highway 131.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...Small Craft Advisory until 11 AM EST Monday for LMZ844>849.

&&

$$

SYNOPSIS...EBW
SHORT TERM...EBW
LONG TERM...Ostuno
AVIATION...Laurens
HYDROLOGY...JAM
MARINE...EBW



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.