Area Forecast Discussion
Issued by NWS Grand Rapids, MI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
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

000
FXUS63 KGRR 161738
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
138 PM EDT Sun Jul 16 2017

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 330 AM EDT Sun Jul 16 2017

A cold front will drop south through the state today bringing with
it some scattered showers and thunderstorms. Showers and storms will
be most numerous this afternoon in the far south and southeast parts
of the Lower Peninsula. High pressure will build in tonight and the
first part of the work week. Dry weather is forecast from tonight
through Tuesday.

&&

.SHORT TERM...(Today through Tuesday)
Issued at 330 AM EDT Sun Jul 16 2017

Main concern in the short term pertains to the chances for showers
and storms today as a cold front progresses south through the
forecast area. The remainder of the short term will feature high
pressure which will bring fair weather.

The cold front is situated from Northeast Lower Michigan to near
Ludington at 07z. By 18z, the front should be in or exiting the CWA
to the south. Feel our best chances for showers and storms will be
along and ahead of the front, so cannot see much more than isolated
to scattered development. The HRRR experimental and the NAMnest both
show similar evolutions. The best activity this afternoon looks to
develop to our south and east. The upper trough will be overhead
this afternoon however so cannot rule out an isolated shower or
thunderstorm this afternoon over the east and south. Have chances
for precipitation in the 20-40 percent range for the most part.

After today, quiet weather is a result of high pressure that will be
situated over the area. Time/height RH progs and plan view layer RH
procedures both show mainly clear to at worst partly cloudy skies
from tonight through Tuesday. Overall, temperatures will be close to
normals for this time of year in the short term.

.LONG TERM...(Tuesday night through Saturday)
Issued at 330 AM EDT Sun Jul 16 2017

The zonal flow pattern will continue through much of the week before
the upper flow becomes somewhat northwesterly by the weekend. A cold
front is progd to move through Wednesday night and Thursday. Both
the ecmwf and gfs show quite a bit of pcpn during this time. The
extra boost in pcpn likely is from a short wave that interacts with
the front Thursday. Both models show this so confidence is medium at
this point that we`ll see some showers/storms toward the end of the
week. High pressure briefly builds in Thursday night and early
friday before the front moves north as a warm front. Again both
models show this warm front to be active and so we may see more
showers/storms Friday night into Saturday.

Temperatures will be fairly summer-like with highs in the lower to
mid 80s and dewpoints in the 60s, which will make the air feel
humid.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 136 PM EDT Sun Jul 16 2017

Ceilings in the 1500 to 2500 foot range will persist early this
afternoon across southern central Lower Michigan before clouds
scatter out later this afternoon. Then VFR conditions should
prevail into Monday afternoon. Winds will be north around 10 knots
today and northeast around 5 knots tonight.

&&

.MARINE...
Issued at 330 AM EDT Sun Jul 16 2017

North winds will increase behind the cold front today into the 10 to
20 knot range with gusts at times over the water to around 25 knots.
Waves will build into the 3 to 5 foot range today. Maintained both
the Small Craft Advisory and the Beach Hazard Statement from today
into tonight. The waves build this morning up near the points and
the remainder of the marine zones to the south this afternoon.
Dangerous swim conditions will develop today, especially on the
north sides of north piers. High pressure will bring a quiet period
on the lake from late tonight through Tuesday morning.


&&

.HYDROLOGY...
Issued at 330 PM EDT Sat Jul 15 2017

Streamflow on a few rivers has returned to normal levels, while the
majority continue to run above normal. Almost all rivers in the
forecast area are falling or beginning to fall.

Little has changed in the forecast with scattered storms possible
tonight into Sunday. This will result in rainfall amounts generally
less than one-quarter of an inch. There is the possibility that a
storm or two could be strong. In the event a strong storm does
develop, localized amounts may be higher.

In the bigger picture, precipitation amounts over the next week do
not look all that concerning. No flooding is expected at this time.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement through late tonight for MIZ037-043-050-
     056-064-071.

LM...Small Craft Advisory until 4 AM EDT Monday for LMZ844>849.

&&

$$

SYNOPSIS...Duke
SHORT TERM...Duke
LONG TERM...04
AVIATION...Ostuno
HYDROLOGY...JAM
MARINE...Duke



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