Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus63 kgrr 140526 

Area forecast discussion
National Weather Service Grand Rapids Michigan
1226 am EST Sat Dec 14 2019

Latest update...

issued at 155 PM EST Fri Dec 13 2019

* some fog possible tonight

* drizzle and freezing drizzle possible on Saturday

* wintry mix may lead to slick spots on roads Saturday afternoon
through Sunday morning

* light snow possible early next week


Discussion...(this evening through next friday)
issued at 155 PM EST Fri Dec 13 2019

The main challenges over the forecast period deals with the
potential for impacts.

Tonight there could some fog around the area. Temperatures will be
near freezing. Thus a risk for a few icy spots exists. One
limiting factor will be the cloud cover from the wave of low
pressure lifting up the Appalachians. That shield of clouds will
exist over much of the County Warning Area for at least part of the night.

On Saturday and more so into Saturday night...light precipitation
will be around. Temperatures during the day are forecasted to
rise above freezing...thus little or no impact is projected during
the day. As we go through the late afternoon hours into the the
evening...the temperatures are likely to fall below freezing. Mid
level height falls occur as a trough digs Down. Lake moisture
could feed into this system as it tracks through the Great Lakes
region. Initially the dgz looks unsaturated later Saturday
afternoon into the the first half of the night. Then it is
forecasted to become barely saturated. All this points to a risk
for a variety of light wintry precipitation types. Given the
potential for below freezing temperatures we could see some

For Monday into Tuesday...guidance continues to track an area of
low pressure up the Ohio Valley. Southern parts of the County Warning Area from
Kalamazoo to near Jackson are shown to be on the northwest fringes
of the snow shield. Most model solutions keep the axis of heavier
snow across Indiana and Ohio. We will feature relatively high pops
for southern parts of the County Warning Area with light accumulations. We will
need to monitor the system closely as a northward shift in the
track could put more snow into our region. Following the passage
of this storm system...a temporary surge of Arctic air moves in.
This will increase the lake effect snow which could lead to some
travel impacts for the area along and west of a Big Rapids to
Battle Creek line.


Aviation...(for the 06z tafs through 06z Saturday night)
issued at 1226 am EST Sat Dec 14 2019

VFR ceilings should continue for much of the overnight hours
before we see MVFR begin to move in near mid-morning. IFR is then
expected to develop later in the late morning to afternoon.
Meanwhile patchy fog will be possible into the morning. Icing is
possible in the cloud layer along with flurries and/or drizzle at
times in the afternoon.


issued at 155 PM EST Fri Dec 13 2019

The pressure gradient will remain relatively weak through tonight
which will act to keep the wave heights low. Then Saturday and
more so Saturday night a northwest wind will develop and
strengthen. We may need marine headlines to account for the wind
and wave action. The potential for hazardous condition may exist
into Sunday.

Another storm system early next week will be followed by the
arrival of another Arctic airmass. Hazardous weather conditions
will likely persist/redevelop.


issued at 711 PM EST Fri Dec 13 2019

River levels across most of west Michigan remain significantly
higher than normal for this time of year, but are slowly trending
down. The Maple River at Maple Rapids is still hovering around
bankfull, but is following the trend of the other rivers with a slow

Of note, a small freezeup ice jam on the Muskegon river between Big
Rapids and Rogers dam continues to cause minor flooding to several
streets and a few homes in the area. Limited reports suggest water
levels have been mostly steady today. Water levels around ice jams
are wildly unpredictable, so some fluctuations both up and down can
be expected over the next few days, but the overall trend should be
slowly downward as warmer temperatures are limiting the growth of
new ice that can come down the river and reinforce the ice jam.


GRR watches/warnings/advisories...


National Weather Service Glossary of Abbreviations