Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 151743

Area Forecast Discussion
National Weather Service Grand Rapids MI
143 PM EDT Sat Oct 15 2016


Issued at 330 AM EDT Sat Oct 15 2016

A front will meander across the region the next few days bringing
periodic showers and a few thunderstorms. Today will be dry as a
cold front approaches from the west. Showers and storms will be
numerous overnight as the boundary presses into the area from the
north. The front stalls in the area on Sunday before lifting back
north as a warm front Sunday night and Monday. Showers and storms
will gradually diminish from Sunday into Monday as the front works
back northward. It will be mild this weekend into early next week as
winds will be southerly.


Issued at 1019 AM EDT Sat Oct 15 2016

Updated to add a small craft advisory to the St Joseph to South
Haven marine zone and also increased cloud cover grids based on
latest satellite and neph analysis trends.


.SHORT TERM...(Today through Monday)
Issued at 330 AM EDT Sat Oct 15 2016

Ascertaining chances for showers and thunderstorms was the main
focus of the short term. An oscillating front will be the forcing
mechanism for the showers and storms.

Today looks to be dry as the front will still be upstream. The
concern today is the extent of lower clouds. Models are suggesting
we will see a good deal of clouds through the morning and early
afternoon hours at least. Partly sunny to mostly cloudy skies today
with mild readings in the mid to upper 60s.

Tonight will likely be the period in the short term with the highest
chances for showers/storms. Have 70-90 pct pops tonight in many
areas as moisture transport increases. Instability does not look all
that great (1000 J/KG CAPE values or lower). Thinking we will see
some embedded storms but any severe threat looks very low.

Sunday the boundary hangs up and showers and storms will persist,
especially in the morning. Clouds will continue to be in place
across the area which will limit high temps to around 70.

Sunday night and Monday the front lifts north as a warm front and
takes the bulk of the precipitation with it. If we can clear out
some on Monday we may make a run at 80 degrees with southerly flow.

.LONG TERM...(Monday night through Friday)
Issued at 330 AM EDT Sat Oct 15 2016

The ECMWF has trended quicker with the mid week front, now showing
it coming through Monday night.  However the GFS and it`s ensembles
still favors a Tuesday evening front.  Will maintain the consistent
thoughts on the front and monitor the changing ECMWF.  Even so, the
front continues to seem to lack deep moisture so rain chances Monday
night and Tuesday will remain low in the forecast.

Temps will cool behind the front, but it looks like this will be a
gradual process each day through mid and late week.  The upper flow
behind the front remains rather zonal through Wed, so expect a more
gradual trend rather then a sudden drop in temps Wed into Thu.  An
easterly flow around high pressure to our NW should keep the area
dry Tuesday night through Wednesday night.

The models differ Thu into Fri with the timing of the next upper
trough.  This timing will not only impact temps, but also how much
Gulf moisture we may be able to tap into.  At this point it appears
much of the moisture should hold to the east, over the Appalachian
chain. Guidance is showing pcpn chances in this time frame, but this
may be limited this far west, so we will continue to monitor. Expect
with the approach of the upper trough that we will continue to see
cooler temps each of Thu and Fri.  After mid and upper 70s on
Tuesday we should cool to the low to mid 50s for highs on Friday.


.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 143 PM EDT Sat Oct 15 2016

Conditions have improved a bit this afternoon after the widespread
IFR this morning. Southwest winds gusting to 20 knots will continue
which will limit the potential for any fog through this evening.
Areas IFR and LIFR conditions are expected later tonight and into
Sunday morning as low clouds, fog and drizzle expands across Lower


Issued at 330 AM EDT Sat Oct 15 2016

Decided to expand the Small Craft Advisory one zone further south,
so it is not in effect from South Haven northward to Manistee. In
addition, the time was extended to 15z Sunday morning.

The strongest winds will be over the lake today and tonight, before
subsiding some into Sunday. Waves of SCA height spread into the
South Haven to Holland zone both today and tonight, so the extension
in area to the south looks good. Waves in the northern zones will
likely peak in the 5 to 8 foot range.

After a brief respite on the lake Sunday into Sunday night, waves
ramp up once again on Monday.


Issued at 1146 AM EDT Sat Oct 15 2016

River levels are running above normal for this time of year in the
upper half of the Grand basin, including Hastings, Ionia, and
points upstream. Basin average rainfall amounts approaching one
inch are possible Saturday night through Sunday in a portion of
the area. The typically flood-prone points of tributaries in the
upper half of the Grand River basin may deal with rises to above
bankfull if widespread greater than one inch of rain is received,
but this is not the most likely scenario.


LM...Small Craft Advisory until 11 AM EDT Sunday for LMZ844>849.



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