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Area forecast discussion 
National Weather Service Grand Rapids Michigan
732 am EDT Friday Aug 22 2014

Latest update...

issued at 323 am EDT Friday Aug 22 2014

A warm weekend is in store with morning fog and some scattered
thunderstorms today and dry weather expected Saturday and Sunday.
Monday will be hot with highs in the upper 80s to near 90. A cold
front moves in for middle week with much cooler temperatures for the
end of the week and lower humidity.


Short term...(today through sunday)
issued at 323 am EDT Friday Aug 22 2014

Precipitation chances and fog will be the main items to address in the
short term. Overall...precipitation coverage looks to be scattered today
and have dropped probability of precipitation for Saturday and Sunday altogether...though a
few pop up showers are not out of the question on Saturday.

Areas of fog are likely through about 13z today given abundant low
level moisture and largely calm winds. Low stratus will likely
extend into the morning hours and have kept a rather cloudy forecast
in through middle day. Many areas will stay mostly cloudy for the
entire day. Precipitation wise...have gone with a scattered wording to
showers and thunderstorms during the day mainly near and south of
I-96 with just isolated activity north of there. Plenty of
instability is in place near/south of I-96 with sb cape values over
1000 j/kg and lifted index values around -3 with halfway decent middle
level lapse rates between 7c/km and 8c/km. Dew points will continue
to hover in the low 70s. Perhaps some source of lift will evolve
during the day with light easterly winds across the central County Warning Area
converging with light and variable winds across the Lakeshore
counties and Lake Michigan. But this activity won't be widespread
and thus have probability of precipitation no higher than 40% across the far south including
azo and jxn.

I would envision Saturday and Sunday being completely dry for the
County Warning Area outside of a few pop up showers on Saturday. This threat is
probably low enough to omit from the forecast. The h500 ridge should
be almost directly overhead by 12z Sunday. As this progresses
in...we will be capped and unable to form convection. The hot
temperatures won't arrive by Sunday it appears. H850 and surface winds
stay east-southeasterly Saturday and Sunday...preventing the real
warmth from getting into SW lower Michigan. Most locations stay in the low
80s for highs today and Saturday while the middle 80s work their way in
for Sunday.

Long term...(sunday night through thursday)
issued at 323 am EDT Friday Aug 22 2014

Long term begins with a very middle Summer looking upper ridge
overhead. The ridge breaks down into middle week as the system lifting
northeast through the plains in the short term crests the ridge and
dampens it with time. What this means for hot and humid to
begin the long term Sunday night into Tuesday...with the weather
becoming more active middle next week. Around 90 looks plausible for
highs both Monday and Tuesday.

Showers and storms will be most numerous from Tuesday night through
Wednesday night when a frontal boundary is forecast to move through
the area. Some of the precipitation may linger into Thursday as the
boundary slides south of the area.

Do not see much in the way of precipitation Sunday night into Monday
with the mean ridge position overhead. Chances for showers and
storms (20/30 pct) will creep in from the northwest Monday night
into Tuesday...but feel the better chances will hold off into middle

The GFS is more ambitious in bringing troughing into the area
towards the end of the forecast period and therefore cooling things
down quite a bit. Am a bit more in favor of the less amplified European model (ecmwf)
out at this range in the forecast.


Aviation...(for the 12z tafs through 12z Saturday morning)
issued at 732 am EDT Friday Aug 22 2014

Main aviation concern the next 24 hours is low stratus ceilings
and fog. Widespread stratus and fog are draped across the taf sites
this morning with some sites reporting vlifr conditions. Expect a
slow improvement through the course of the morning...but it will
take much of...if not all of the morning to really improve
conditions. VFR weather though may not settle in until middle
afternoon if at all. A bit concerned about MVFR ceilings hanging
on all day.

This evening...MVFR ceilings should gradually expand again to all
taf sites with the potential of ceilings and visibilities dropping
to IFR levels or below once again. Kept the tafs a bit more brief
and did not provide siginificant detail overnight...but we could
be looking at a repeat of this morning (widespread LIFR/vlifr).

There is a chance of showers and storms this afternoon and
evening...but the chances are not great. Left any mention of
precipitation out for now and will let the 18z taf forecaster
take another look.


issued at 323 am EDT Friday Aug 22 2014

Marine fog will be the primary problem for mariners now through
the weekend it appears. Very humid conditions over a still Cool
Lake Michigan along with mainly light winds will be conducive to
areas of fog. Wave action will be minimal through the weekend.


issued at 323 am EDT Friday Aug 22 2014

Significant precipitation is not expected for the next several
days. Scattered thunderstorms today are not anticipated to produce
heavy rainfall amounts on average.


GRR watches/warnings/advisories...


short term...Hoving
long term...Duke

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