Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 241115
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
715 AM EDT FRI JUN 24 2016

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 311 AM EDT Fri Jun 24 2016

High pressure will being fair weather through Saturday, then a
cold front moves in Saturday night and Sunday with a few showers
and thunderstorms.

&&

.SHORT TERM...(Today through Sunday)
Issued at 311 AM EDT Fri Jun 24 2016

Only forecast challenge in the near term is timing and coverage of
POPs for Saturday night and Sunday. Lowered QPF and will probably
have to eventually lower pops to chance or slight chance since
this appears to be yet another event where there is little forced
ascent via strong sfc convergence and/or favorable upper jet
dynamics, which in this case will be well up in Canada.

Sfc-based instability increases on Sunday as the cold front
pushes into juicy airmass, so there could be some diurnal
enhancement of convection, but this does not appear to be a
widespread rain event given the lack of large scale ascent.

.LONG TERM...(Sunday night through Thursday)
Issued at 311 AM EDT Fri Jun 24 2016

The long term portion of the forecast is looking mostly dry for the
area, with temperatures running around average to a little below
average.

We expect that showers and storms from Sunday should have exited the
CWFA by the beginning of the long term Sunday night. The cold front
will have exited the area, sweeping out the moisture and
instability. Temperatures will not drop significantly behind this
cold front. A secondary cold front dropping through the area on
Monday in the N/NW flow around the large amplitude upper trough will
usher in much cooler temps. Rain chances with this front are very
low with much drier air in place.

Tuesday will be the coolest day of the long term with a nice push of
cool air straight from the N/NE. If any rain would occur in the long
term, it would be on Tuesday. That said, the chances are quite low
at this time with the front moving through on Monday, the supporting
upper trough moving through Monday night, and the continued dry air
in place. About the only hope on Tuesday for a shower would be the
cyclonic nature of the upper flow allowing for a pop up shower with
diurnal heating.

The remainder of the long term then will feature moderating
temperatures and continued dry conditions. The upper trough in place
early in the week will give way to less troughing. Weak long wave
troughing will persist over the Ern portion of the country. NW flow
aloft will keep temps from getting too warm.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
Issued at 715 AM EDT Fri Jun 24 2016

VFR conditions will continue through tonight. Winds will be east
aob 10 knots today.

&&

.MARINE...
Issued at 311 AM EDT Fri Jun 24 2016

Winds and waves will be light today but south winds will increase
on Saturday and waves will begin building Saturday night as
showers and thunderstorms move over Lake Michigan


&&

.HYDROLOGY...
Issued at 310 PM EDT Thu Jun 23 2016

Locally heavy rainfall (an inch or more) fell in far Southern Lower
Michigan through this morning. River levels are still running at to
a little below normal. Main stem river flooding is not expected. An
additional half inch of rain, possible Sunday into Monday, should
also be safely absorbed by the river system.

&&

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

$$

SYNOPSIS...Ostuno
SHORT TERM...Ostuno
LONG TERM...NJJ
AVIATION...Ostuno
HYDROLOGY...63
MARINE...Ostuno



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