National Weather Service Raw Text Product

606 
FXUS63 KGRR 200258
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
958 PM EST Tue Feb 19 2019

LATEST UPDATE...
Update

.SYNOPSIS...
Issued at 237 PM EST Tue Feb 19 2019

- Snow changing to light freezing rain Wednesday

- No as cold end of the week into the weekend

- Windy with rain to snow over the weekend into early next week

&&

.UPDATE...
Issued at 957 PM EST Tue Feb 19 2019

Based on the latest HRRR/Nam guidance which are quicker developing
the incoming precip, will move up the start time of the advisory 
to 5 am along the I-94 corridor and to 7 am over the rest of the 
area. No other changes needed. WSW update coming soon.

&&

.DISCUSSION...(This evening through next Tuesday)
Issued at 237 PM EST Tue Feb 19 2019

The main weather challenges deal with the potential impacts
through the period.

Guidance has been fairly consistent in drawing up an area of
precipitation from the south Wednesday morning. Generating the
precipitation will be an elevated warm front that advects through
the area. Mid level height falls occur later Wednesday as the mid
level low tracks through the Western Great Lakes region 
supporting additional precipitation then. Initially the soundings 
support a snow onset but a mid level dry slot moves in quickly 
and transitions the type to mainly liquid. With surface 
temperatures forecasted to remain below freezing for much of the 
period...freezing rain/drizzle look likely to happen. Only a light
coating of ice is expected with most locations seeing a tenth of 
an inch or less. Still this is expected to yield impacts...mainly 
in the form of slippery conditions on untreated surfaces. The main
forcing pulls out during the evening allowing for a diminishing 
trend to the precipitation. There is some potential for the 
freezing drizzle to linger past midnight for parts of the 
region...but confidence it low on that happening. We have issued a
Winter Weather Advisory for this system Wednesday into Wednesday 
evening...which may need to be extended if confidence grows on the
precipitation lingering past midnight.

A break in the action is forecasted Thursday into the start of
Saturday. We may see above normal temperatures for a change. The
next storm system will be rolling in over the weekend though.

Warm air advection strengthens Saturday into Saturday night.
Overall this next system looks relatively warmer...so it should
primarily be a rain event for much of the region. The main impact
may very well be the wind. This is because the pressure gradient
tightens up considerably on the backside of the departing storm
Sunday. The High Res Euro is supporting better than 40 knots of
wind which would bring down some limbs. The GFS is considerably
less with the wind...thus some uncertainty exists on the
potential. We will need to monitor the thunder potential with some
models showing elevated instability moving in. As the colder air 
wraps into the departing storm...a transition to snow is expected 
Sunday afternoon into the evening. This could eventually lead to 
impacts as the surface temperatures fall to near freezing during 
the evening.

Lastly a third storm system is shown by the models to track in
from the west on Tuesday. At this time this system is forecasted
to be a colder storm with soundings supporting snow. There is some
potential for travel impacts given the risk for snow and surface
temperatures potentially below freezing.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 715 PM EST Tue Feb 19 2019

VFR weather will prevail most of tonight but expect a rapid 
transition to MVFR/IFR from south to north toward 12Z Wed as snow
spreads in quickly from the south. The snow will transition to 
light freezing rain/drizzle by midday, with IFR becoming more 
widespread/persistent as the day wears on. Winds will increase 
out of the east-southeast to 10-20 kts by daybreak Wed, with some 
higher gusts possible. 


&&

.HYDROLOGY...
Issued at 237 PM EST Tue Feb 19 2019

High temperatures will rise above freezing during the middle and end 
of this week, causing some snow to melt. We will also see two 
precipitation events through the weekend, although amounts with the 
first event will be very light. A wintry mix will spread into the 
area Wednesday, with some light rain possible south of I-96 before 
precipitation tapers off or changes to snow overnight. A mix of rain 
and snow is then expected late Saturday and Sunday, with rain 
amounts potentially reaching between one-quarter and one-half inch. 
The combination of melting snow and rain will cause water levels to 
rise through the weekend and into early next week, putting some of 
the smaller rivers and streams at bankfull stage. No flooding is 
currently expected. 

There continues to be a major ice jam causing ongoing flooding in 
the City of Portland. Water levels there will continue to fluctuate 
up and down in response to shifting and changing ice conditions over 
the next few days. Ice jams in other locations are still possible. 

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 7 AM to 10 PM EST Wednesday for 
MIZ037>040-043>046-050>052-056>059-064>067.

Winter Weather Advisory from 5 AM to 7 PM EST Wednesday for 
MIZ071>074.

&&

$$

UPDATE...Meade
SYNOPSIS...MJS
DISCUSSION...MJS
AVIATION...Meade
HYDROLOGY...HLO