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
FXUS63 KGRR 192230

Area Forecast Discussion
National Weather Service Grand Rapids MI
630 PM EDT Wed Oct 19 2016


Issued at 630 PM EDT Wed Oct 19 2016

Light rain will spread northeast into southern lower Michigan
tonight as a low pressure system, developing in the Ohio Valley
early tonight heads toward northeast Ohio by mid morning Thursday.
Rain will be rather persistent south of a line from Lansing to
Kalamazoo Thursday morning. Locations between there and I-96 may
see a little light rain but no significant rain is expected north
of I-96.

Colder air will be filtering into the area from the north through
the end of the week and this weekend. This cold air will bring the
potential for some lake effect rain showers along the coastal
communities for Thursday and Friday.

The weather will dry out for the weekend and continue into early
next week. Moderating temperatures can be expected also early next


.SHORT TERM...(This evening through Friday night)
Issued at 319 PM EDT Wed Oct 19 2016

Our attention in the short term is on the rain chances with the
system scooting by to our south, and lake effect rain chances behind
the system for late Thu into Fri.

We are seeing some mid level cloud cover developing overhead this
afternoon across the mid portion of the cwfa. This is coming via mid-
level fgen in response to the rrq of the upper jet streak to our NE.
The air below about 15k ft is still fairly dry, and not allowing
any of the moisture to reach the ground.

We will see rain chances increase this evening and overnight across
the SE portion of the area. The current mid level fgen will be
moving out, but we will see moisture return ahead of the short wave
across the Central Plains try to make it`s way toward the area. The
stalled out front that the sfc wave will move along will remain well
south of the area. This will allow for drier air to be drawn down
from the north, and limit the northward advancement of the rain. The
rain will then gradually move out on Thu as the sfc wave gets
pushed out of the area.

Colder air will then be drawn down in the wake of the system for Thu
night and Friday. The upper wave actually amplifies a bit and holds
over the region. The cold pool aloft and cyclonic flow will allow
for sufficiently cold enough air to move in to bring some chances of
lake effect rain showers. H850 temps are expected to drop down to
around -2 to -4c producing delta t`s approaching 20c. The flow is
generally expected to be from the NNW, keeping most of the rain
showers along the coastal counties. Inland areas could actually see
some frost Thu night as they very well could clear out with the NNW

Rain showers should tend to diminish late Fri/Fri night. The upper
wave will lose control of it`s hold over the area at that time, and
ridging will start to build in. There could be another night of
frost inland.

.LONG TERM...(Saturday through Wednesday)
Issued at 319 PM EDT Wed Oct 19 2016

A mid level ridge will build in from the northwest on Saturday. This
system will act to diminish any risk for precipitation.  As this
feature moves east of MI...a strengthening and deepening southwest
flow will develop.  So a brief warming trend is forecasted going
into Sunday.  Above normal temperatures are forecasted for Sunday.

A mid level wave will move in from the northwest on Sunday.  Most of
the lift and deeper moisture is forecasted to stay north of the CWA.
Thus the risk for rain remains low at this time.  On the backside of
this system...cold air advection returns.  Thus the region is
forecasted to fall back closer to normal temperatures.

A big west coast low pressure system moves into the Rockies by the
middle part of next week.  This will support deeper ridging here in
the Great Lakes Region.  A warm front will be sent northward through
MI Tuesday afternoon into Wednesday.  Thus some showers will be


.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 630 PM EDT Wed Oct 19 2016

For the most part expect VFR conditions to prevail at MKG and GRR
through Thursday evening. Light rain is likely to reach LAN, AZO
and BTL between 06z and 12z. In the JXN area the rain may be
a little heavier during the mid morning hours of Thursday.
JXN will likely have IFR conditions during the mid morning hours
of Thursday. LAN, AZO and BTL are a little more questionable but
at this point it appears the northeast winds at low to mid levels
will bring enough moisture off Lake Huron, so that combined with
the light rain, MVFR conditons area more than possible Thursday

All of this should clear out later in the day Thursday as the
storm system pulls out of the area bringing drier air from the


Issued at 319 PM EDT Wed Oct 19 2016

Winds will pick up late tonight, and more so on Thursday after
relatively light winds today. There may be enough of a wind Thu into
Fri that a Small Craft Advisory may be needed. This wind will
generally be from the NNW.

Another hazard that is possible later this week will be the threat
of waterspouts. The upper system coming over the area will produce
some lake effect rain showers, some of which could have some


Issued at 319 PM EDT Wed Oct 19 2016

Despite rivers running above normal to well above normal through
much of Southwest Lower Michigan, improvement is expected to
continue for a majority of the sites. The lingering question this
afternoon is in the far southeastern corner of the forecast area,
near Jackson. Rainfall tonight into Thursday has the potential to
total between 0.25-0.50 of an inch. These amounts are fairly run-of-
the-mill, but given recent ground saturation, results closer to 0.50
of an inch may lead to within bank rises in that area, especially on
small streams.

Aside from the rainfall mention tonight into Thursday, the next 5-7
days is void of any large impact events. Flooding is not anticipated.




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