Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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641
FXUS63 KGRR 231914
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
315 PM EDT FRI SEP 23 2016

LATEST UPDATE...
Synopsis/Short Term/Long Term/Marine

.SYNOPSIS...
Issued at 315 PM EDT Fri Sep 23 2016

Fair weather will return tonight through Saturday and most of Sunday
with seasonably mild temperatures. A cold front will bring rain and
perhaps a few thunderstorms Sunday night into early Monday. A cooler
airmass will move in behind the front from Monday night
through Wednesday.

&&

.SHORT TERM...(This evening through Sunday night)
Issued at 315 PM EDT Fri Sep 23 2016

Primary short term fcst concerns involve timing rain into our fcst
area Sunday night.

An isolated light rain shower or sprinkle is still possible into
this evening mainly along the I-94 corridor closer to the nearly
stationary frontal boundary that extends across far northern IN/OH.
Otherwise quite a bit of cloud cover will linger overnight and some
patchy fog may develop during the early morning hours Saturday.

High pressure anchored to the northeast of our region will bring
fair weather Satuday through most of Sunday. It will be seasonably
mild in spite of easterly winds Saturday with high temperatures
reaching the middle 60s to lower 70s. It will be a bit milder Sunday
as winds veer to the southeast to south. This in conjunction with
some sun will help to boost max temps into the lower to middle 70s.

The cold front approaching from the west will bring rain showers
Sunday evening that will become more widespread late Sunday night.
Convective potential late Sunday night is fairly low due largely to
frontal timing and weak instability.

.LONG TERM...(Monday through Friday)
Issued at 315 PM EDT Fri Sep 23 2016

Models are in decent agreement in showing the cold front moving east
of the forecast area Monday morning.  Less of a risk for
thunderstorms exists as the main instability axis will be ahead of
this front.  With a post frontal airmass moving in during the day on
Monday the highest potential for measurable rain will be in the
morning.

Some differences show up for Monday night into Tuesday.  The GFS
wraps around considerably more moisture behind the departing system.
This occurs partly because the GFS is much cooler and the lakes add
moisture to this low pressure system.  The new High Res Euro is
still dry as it is not as cool and it keeps the low further north.
Will hold onto the low risk for showers Monday night into Tuesday
given the spread in the models.

Ridging moves in for Wednesday into Friday.  Thus any risk for rain
looks minimal.  A moderating trend to the temperatures will occur as
the ridge builds east for the end of the week.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 115 PM EDT Fri Sep 23 2016

IFR impacts are forecasted to diminish as we go through the
afternoon as the low level humidity will decrease. MVFR is
expected to persist any drying will be limited. There will be some
showers around...mainly for KAZO and KBTL this afternoon. While
some instability will build...the risk for thunderstorms was too
low to include in the forecast.

I have added IFR conditions to the tonight forecast for many TAF
sites. The low level moisture increases again tonight. This could
lead to a period of low clouds and fog. Any fog or low clouds will
lift during Saturday morning.


&&

.MARINE...
Issued at 315 PM EDT Fri Sep 23 2016

Northeast to east winds in the 5 to 15 kt range through Saturday
will result in minimal wave heights mainly in the 1 to 2 foot
range. Winds will veer to the se to south and strengthen somewhat on
Sunday out ahead of an approaching cold front. This will result in
building wave heights to at least 2 to 4 feet and potential for
wave heights to flirt with small craft criteria by Sunday
afternoon.

&&

.HYDROLOGY...
Issued at 1032 AM EDT Fri Sep 23 2016

Hydro concerns are minimal through the weekend, as little rain is
expected and river levels are around normal for the time of year.
Showers and thunderstorms are expected Sunday into Monday night with
additional rain possible Tuesday into Wednesday. Around 1 inch of
rain is expected and therefore rivers and streams should remain
below bankfull through the week.

&&

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

$$

SYNOPSIS...Laurens
SHORT TERM...Laurens
LONG TERM...MJS
AVIATION...MJS
HYDROLOGY...63
MARINE...Laurens



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