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Area forecast discussion 
National Weather Service Grand Rapids Michigan
330 PM EDT Friday Aug 22 2014

Latest update...
synopsis/short term/long term/Hydro/marine

issued at 330 PM EDT Friday Aug 22 2014

Warm and humid weather will prevail through at least the middle part
of next week. The hottest days will be Monday and Tuesday when highs
may reach 90 degrees with heat indices as high as the middle to upper
90s. Precipitation chances will be very low over the next several
days with only an isolated shower or storm possible in the afternoon
and early evening hours.


Short term...(this evening through Sunday night)
issued at 330 PM EDT Friday Aug 22 2014

Not a whole lot of change expected synoptically over the weekend
with the surface warm front remaining south of Michigan. Moist/light low level
easterly flow with surface dew points near 70 should promote considerable
stratus/fog at night into the morning hours. 800 mb temperatures dont change
much either with continued east/southeast flow... implying similar high temperatures
of mainly 80 to 85 although a bit warmer than that SW of GRR
especially Sunday.

Will keep the forecast dry on Saturday despite the possibility of an
isolated shower or two. The probability is really only around 10
percent. Height rises and developing upper ridge/subsidence...
particularly on Sunday... should tend to suppress convective
development over the weekend.

In the near term... thick stratus deck continues to hang tough today
over much of the area even at middle afternoon. Instability remains
limited with ml convective available potential energy below 1000 j/kg and its been difficult
generating any diurnal convection. Have maintained a 20 pop through
middle evening should the stratus break soon... although it seems the
only available trigger would be convergence along the lake breeze
front which also has had a hard time developing today.

Long term...(monday through friday)
issued at 330 PM EDT Friday Aug 22 2014

No major changes needed to the long term portion of the forecast. The
beginning of next week looks very warm and humid. Upper ridging is
expected to start out the week overhead...and gradually get
flattened by the upper trough lifting NE out of the plains states.
We continue to think that there is a very small chance of a shower or
storm on Monday...however plenty of capping is present of forecast
soundings with a warm nose present aloft.

The chance of rain will gradually increase then into mid-week...looking
to peak around the Wednesday-Wednesday night time frame right now. We will see a
cold front drop south into the area on Tuesday. There does not look to
be much fanfare initially with this front as it is weakening with
the upper support remaining well north of the area. The best chance of
rain will come as the front will be stalled out by Wednesday...and another
trough moves trough bringing a wave along the front. Quite a bit of
moisture will be heavy rain potential will have to be

The thinking right now is that we should dry out and cool off for
the end of next week. The previous model runs have been showing the
trough moving through and pushing the front well south of the area.
Some uncertainty has cropped up as the new European model (ecmwf) has closed off the
upper low and brings an additional wave in and associated precipitation for
the end of the week. We tend to think for now that the European model (ecmwf) is
showing its bias of over-amplifying systems too much. We have left
Thursday and Friday dry for now...and will monitor the latest trends with
this trough/low.


Aviation...(for the 18z tafs through 18z Saturday afternoon)
issued at 144 PM EDT Friday Aug 22 2014

Main issue for aviation interests for the next 24 hours will be
low clouds and fog. Fog from earlier has diminished across most
of the area...however plenty of low clouds remain. The low clouds
have generally lifted into the MVFR category...and should lift and
mix out more this afternoon as late August sunshine works on the
soupy air mass. The clouds have limited the convective potential
this afternoon...however some showers still could pop this
afternoon as the clouds thin out. We have put in vcsh to account
for this.

We expect that fog and/or stratus will redevelop overnight tonight
with light winds and the air mass remaining moist. We have hit the
fog/stratus hard...bringing conditions down at least into the LIFR
category. It will slowly dissipate on Saturday late in the
morning/early in the afternoon.


issued at 330 PM EDT Friday Aug 22 2014

Very moist air mass and light winds will make fog patches and hazy
conditions a possibility on Lake Michigan through the weekend.
Visibilities may be greatly reduced at times in dense fog patches.


issued at 330 PM EDT Friday Aug 22 2014

There are no Hydro concerns at this time.


GRR watches/warnings/advisories...


short term...Meade
long term...njj

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