Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 241800
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
200 PM EDT TUE MAY 24 2016

LATEST UPDATE...
Hydro

.SYNOPSIS...
Issued at 330 AM EDT Tue May 24 2016

High pressure will slip away from the region today but should
provide one more dry day. A persistent southerly flow of air will
bring very warm and humid conditions for the mid to late week period
along with a daily risk of showers and thunderstorms.

&&

.SHORT TERM...(Today through Thursday)
Issued at 330 AM EDT Tue May 24 2016

The sfc front remains to our west today and will be the primary
focus for convection. Will have a dry fcst with the exception of low
chance pops north of mkg late in the day as the front gets a bit
closer. Otherwise the stable southwest flow off lake michigan,
lack of any focus for convection, and capes of only a few hundred
joules support a dry fcst.

Even tonight as the front comes into the area the coverage of rain
should be minimal as diurnal component is lost, and will carry only
low chance pops. Actually the sfc front weakens overhead and becomes
rather ill-defined, then begins to rebound north as a warm front on
Wednesday. Better instability is progged on Wednesday with sfc based
capes near 2000 J/KG. However it`s unclear if the warm front will
still be in our area or will have lifted into nrn lower mi. Diurnal
convection should tend to favor the sfc convergence along this
boundary.

The best chance of showers and storms in the short term period is on
Wednesday night as a shortwave and 40 kt low level jet impact
the area. Will carry likely pops during this time. After this
activity moves out of the area Thursday morning, some scattered
diurnal convection could re-fire east of the lake breeze front in the
afternoon.

.LONG TERM...(Thursday night through Monday)
Issued at 330 AM EDT Tue May 24 2016

Little change to the extended portion of the forecast.  The area
will remain warmer than normal, but periodic rains will be possible.

Upper ridging will still prevail over the eastern U.S. through the
weekend and into next week. This will continue to pump a warm and
moist air mass into the Great Lakes. This will keep daytime temps in
the upper 70s to mid 80s each day.  There should also be a period
from Thursday Night into Saturday where we should be rather humid,
with dew points expected to be in the 60s.

Showers and thunderstorms will be a possibility however through the
period.  The best chance of pcpn seems to be Friday and Saturday
when a northward moving low level jet sets up over the western Great
Lakes.  This will put Lower Michigan in an area of low level
convergence that will work with instability across the area.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 134 PM EDT Tue May 24 2016

The moisture will be gradually increasing through the period.
Showers and thunderstorms are expected to develop over in WI this
afternoon and evening. As they shift east...they are expected to
weaken. Thus I will only feature a VCSH for KMKG tonight. VFR
clouds will spread into the remainder of the taf sites through the
night. A small risk for fog exists tonight and Wednesday morning.
With Lake MI cold...fog could begin forming as the moist airmass
moves in. This risk will grow as the go through the remainder of
the week. For now...forecasted surface dewpoints into Wednesday
morning do not look high enough to support widespread fog near
KMKG. That could change by Thursday morning.


&&

.MARINE...
Issued at 330 AM EDT Tue May 24 2016

Arrival of higher dew points over the cool lake michigan waters may
lead to areas of dense marine fog as we go through the week. Winds
and waves are expected to remain below advisory criteria in the
short term.


&&

.HYDROLOGY...
Issued at 152 PM EDT Tue May 24 2016

Periodic showers and thunderstorms will move through the region
especially Wednesday night, Friday and Saturday. However, overall
rainfall amounts will likely be variable across the area. Some
locations may pick up well over an inch of rain through the
weekend, while other places much less. A good portion of the more
widespread rainfall could occur Wednesday night as a warm front
lifts through. Thursday and beyond will feature some diurnally
driven convection that could produce locally heavy rainfall...but
basin average rainfall is not expected to be excessive. Smaller
creeks and rivers could be susceptible to quick rises given this
setup. Main stem river flooding does not look likely.

&&

.GRR Watches/Warnings/Advisories...
MI...None.
LM...None.
&&

$$

SYNOPSIS...Meade
SHORT TERM...Meade
LONG TERM...JK
AVIATION...MJS
HYDROLOGY...Hoving
MARINE...Meade



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