Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 170726

Area Forecast Discussion
National Weather Service Grand Rapids MI
226 AM EST Fri Feb 17 2017

Synopsis/Short Term/Long Term/Marine

Issued at 226 AM EST Fri Feb 17 2017

Unseasonably warm temperatures will persist well into next week with
highs commonly in the 50s, which is 15 to 20 degrees above normal
for this time of year. After a dry weekend, rain chances return
for Monday night and Tuesday.


.SHORT TERM...(Today through Sunday)
Issued at 226 AM EST Fri Feb 17 2017

Main concern through the period is fog developing early Saturday
morning with increasing dewpoints streaming into the area,
particularly farther north where residual snowpack may exist. Have
introduced patchy fog in the forecast but this could overperform and
perhaps last well into the day Saturday, which could also result in
highs below the currently advertised upper 40s for the US-10 region.
As noted in the marine discussion below, there also is some concern
for fog along the immediate lakeshore during this time.

.LONG TERM...(Sunday night through Thursday)
Issued at 226 AM EST Fri Feb 17 2017

Surface and upper ridging continues to build over SW MI leading to
quiet weather Monday and well above normal temps.  Monday and
Tuesday look like the warmest days with highs in the 50s.  However
as the ridge drifts east, the rain chances will return late Monday
night into Tuesday.  Decent agreement in the models showing a cold
front should come through Tuesday afternoon which would favor most
of the rain coming Tuesday morning.

The pattern becomes more zonal and progressive late in the long
term.  This should bring another cold front through the region Wed
night.  This front should have a better push of cool air behind it.
So it should become less warm, Wed night and Thu, but still a bit
above normal.


.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1204 AM EST Fri Feb 17 2017

VFR conditions are expected for the bulk of the next 24 hours with
just mid and high clouds over the region. Southerly winds will
increase by mid/late Friday morning and hold around 10 knots into
the evening.

There could be some fog that develops late Friday night as higher
dew points move into the area. Somewhat questionable how this
plays out since we expect the wind will stay up. This may reduce
the amount of fog development, however will put some MVFR in the
LAN TAF after 03Z Friday night for starters.


Issued at 226 AM EST Fri Feb 17 2017

Primary concern is potential for marine fog Saturday morning into
Saturday as more humid air streams across Lake Michigan. GLERL GLCFS
advertises the cooler nearshore water temperatures to remain in the
upper 30s - similar to forecast dewpoints - so would not rule out
some fog. Onshore flow would also impact the immediate lakeshore
with reduced visibilities.


Issued at 239 PM EST Thu Feb 16 2017

River streamflows are running near to much above normal for mid
February. Fortunately, river levels are slowly falling in the areas
affected by nuisance flooding last week. The next chance for rain
will be on Tuesday, but amounts do not look significant enough to be
a concern.




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