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FXUS63 KGRR 180550
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
1250 AM EST Mon Feb 18 2019

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 218 PM EST Sun Feb 17 2019

- Occasional snow into tonight with accumulations of 1 to 4 inches

- Continued cold through midweek

- Light snow developing Tuesday night and a wintry mix of
precipitation Wednesday

&&

.DISCUSSION...(This evening through next Sunday)
Issued at 218 PM EST Sun Feb 17 2019

The main challenges deal with the potential impacts from the next
couple of storms.

To start...stronger bands of snow continue to persist around the
region...mainly along and south of Interstate 96. These bands of
snow have been forming in a region of mid level FGEN and steeper
lapse rates up around 700 mb. Trends over the past hour or or so
suggest the lift has been weakening and satellite shows a dry slot
working in from the southwest. So it appears the heavy snow will
continue for another hr or so...then a lull may happen. There is
even a potential for freezing drizzle in the dry slot as the DGZ
becomes unsaturated. Looking upstream though on radar the next
round of precipitation is headed our way from IA. This should
arrive later this afternoon and evening which should impact the
advisory area...especially the southern part of it. I would not
rule out a period of heavy snow returning. The snow winds down
from the north mainly after midnight and through the late night
hours. Impacts still look likely for the morning commute even
through the accumulating snow will be done.

A break in the action is forecasted for Monday into Tuesday with
only some lake effect snow showers. Rather cold temperatures are
expected at night with good radiational cooling and fresh snow on
the ground. We lowered the overnight temperatures as a result.

Next up is the storm system for later Tuesday night into
Wednesday. Guidance has been fairly consistent in showing the risk
for impacts from this storm. The combination of warm and moist
air advection along with upper level diffluence will support an
area of precipitation spreading in and remaining over the region
through much of the day. The onset will feature snow arriving near
of just before the Wednesday morning commute. Then as a warm
layer aloft moves in during the day...a wintry mix looks likely
with a period of freezing rain. Headlines may be needed for the
storm system.

The core of the arctic airmass does shift northeastward away from
the region for the end of the week. That will give us a shot at a
period of above normal temperatures.

Another potential storm system could happen on Sunday. The high
res euro is tracking a stronger wave northeastward through the
region. The low levels look too warm for snow based on this
model. The GFS is further east with this storm and result in it
largely missing us. Either way another shot of cold air pulls in
behind it.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1249 AM EST Mon Feb 18 2019

Light snow is winding down and should be over by mid morning.
Cigs/vsbys will gradually improve through the morning becoming VFR
by afternoon.

&&

.HYDROLOGY...
Issued at 1226 PM EST Sun Feb 17 2019

Ice continue to impact the area around Portland. The weather
pattern will remain colder than normal so we do not expect the ice
to break up any time soon. Elsewhere...we are looking at some very
cold overnight low temperatures the next couple of nights. So
there will likely be some additional ice forming. We will continue
to monitor the situation closely.

A moderating trend is forecasted with the temperatures for the end
of the week. At this time any melting would be rather gradual
based on the current forecasts.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 8 AM EST this morning for
MIZ050>052-056>059-064>067-071>074.

&&

$$

SYNOPSIS...MJS
DISCUSSION...MJS
AVIATION...04
HYDROLOGY...MJS
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