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Area forecast discussion 
National Weather Service Gaylord Michigan
149 PM EDT Wednesday Aug 27 2014

Synopsis...
issued at 358 am EDT Wednesday Aug 27 2014

Clouds and a few sprinkles this morning will fade by late morning
and afternoon...with a plethora of sunshine developing for northern
Michigan. High pressure then settles in for tonight and Thursday
with chilly overnight temperatures. Skies do increase in cloudiness
Thursday...before periodic rain spreads in over much of northern
Michigan for Friday through Saturday night.

&&

Short term...(today through tonight)
issued at 1257 am EDT Wednesday Aug 27 2014

..clouds and a few sprinkles early then sunshine...

Impacts: none.

Current weather and synoptic pattern:

Surface cold front well south and east of US over the eastern Great
Lakes...through Detroit and back through central Illinois. All the
moisture and instability resides along and ahead of this front. Northern
Michigan is within a much drier air mass with area VAD wind profiles
showing northwest flow...and surface winds weakening at 5mph or less. Skies
have cleared last evening with good radiational cooling able to work
on some of the bl moisture that did not mix out totally yesterday
afternoon. As a result...patchy stratus and fog was fairly common.
Further upstream...things were playing out as planned...with
Canadian shortwave trough becoming more defined...with a nice middle
level jet and pocket of weak-moderate 800 mb-500 mb -divq working in over
the top of an area of surface high pressure and dry low level air in the
upper Mississippi Valley. Pockets/band of sprinkles were reaching
ground along/left of the middle level jet.

Synoptic pattern/weather evolution:

The low level will be trying to dry further through the night in the
nearly flow at 800 mb...and have to believe that any stratus will likely
fade with time into daybreak. Could continue to see some patchy
rather insignificant fog in the lowest lying areas where temperatures are
coolest (into the upper 40s). Battling that...will be increased middle
and upper level clouds out ahead of the shortwave trough...which
will overtake most of northern Michigan by daybreak and through middle
morning. Also can not argue with some sprinkles likely affecting
eastern upper and areas mainly along and north of M-32 in northern lower.

This trough and deeper middle and upper level moisture exit by late
morning...with another surge of deeper drier air and subsidence
settling in for the afternoon and nighttime hours. Any chance for
sprinkles will end with plenty of sunshine expected. Remnant bl
moisture will be minimal...but some scattered flat cumulus is likely
to pop up in developing lake breezes across NE lower and interior
eastern upper. Less across eastern upper as the low level air mass
will be drier there. This cumulus fades with evening...and skies
will be clear for a good chunk of the night. Maybe some higher level
cirrus arrives late tonight across Great Bay/Cadillac/Manistee areas
ahead of an approaching vorticity maxima ejected from a weak closed
low in the Central Plains. This will be the feature that brings the
more meaningful weather to US late this work week and this upcoming
weekend.

Highs today ranging from the middle 60s in eastern upper...to the
lower half of the 70s Cadillac to Alpena and areas south. Lows
tonight ought to be quite chilly with good radiational cooling with
surface high directly overhead. Not expecting the bl to mix out greatly
with the inversion overhead. However...a good 25-30 degree diurnal
spread should result in lows in the upper 30s to lower half of the
40s (even many Lakeshore areas where land breezes set up).

Long term...(thursday through tuesday)
issued at 358 am EDT Wednesday Aug 27 2014

Overview...as with any zonal-ish pattern, the long term can be
highly changeable. This is case is no exception as the fast 500 mb
flow has produced changes in the forecast. So the basic overview has
the shallow 500 mb "cutoff" low that slowly moving from the Desert
Southwest to the Central Plains before being absorbed by the 500 mb
flow over the upper Great Lakes on Saturday. Then it looks like
there may be a break on Sunday, before the next 500 mb wave moves
into the region on Monday. The Tuesday forecast will be up in the
air as the slightly more amplified European model (ecmwf) is looks to have another
break while the GFS brings round after round of showers. So the
forecast will look like this...

(8/28)thursday/Thursday night...as was thought the models have been
backing off the timing of the showers/rain over the region as the
500 mb shortwave ridge looks a little more amplified answer the surface
high looks like it keep the return flow out of Michigan until
Thursday night. Models are going with a straight, overrunning rain
scenario with the showalter index showing that elevated thunder is
unlikely as the low moves into the upper Great Lakes.

(8/29)friday/Friday night...models are in good agreement that the
overrunning rain is most likely as the southerly surface flow pushes
into the 30 knot 500 mb jet streak. While there is good upward
motion for the rain would like to see a stronger jet (40+ knots) to
help get the middle level instability (showalter index 0c to -1c) to
produce elevated thunder. This system looks more like a "fall type"
system. It's a bit of a toss up on how the overnight evolves. The
NAM would pushing things through as a cold front which would say
maybe some thunder. The GFS still shows the end of the overrunning
rain. The European model (ecmwf) is showing some instability as the first wave moves
out and the surface low approaches the upper Great Lakes. The European model (ecmwf)
shows -2 to -4c showalter index and k index in the lower 30s. Put in
the slight chance of thunder as the NAM/European model (ecmwf) look right. However,
won't be surprised if there is no thunder.

Extended (saturday through tuesday)...(8/30)saturday...as the surface
low moves through the forecast area, will continue the storms as the
forecast area is in the warm sector. (8/31)sunday...we get on the
back side of the low. So it looks like we get into the wrap around
moisture that will continue the rain showers over the forecast area
in the morning. Looks like we could have a dry period in the
afternoon and evening as we get between two systems. (9/1)labor
day...where we were looking at down playing the rain on Monday, it
has now returned as a surface low spins up and moves in Ontario, with a
50 to 60 knot 500 mb jet pushing into the state. This will kick off
thunderstorms as the system moves into the region. Timing is a
little up in the air as the GFS brings it in during the morning, and
the European model (ecmwf) brings it in during the afternoon. (9/2)tuesday...the 500
mb jet sets up over Michigan on the GFS. While we could get a few
hours reprieve, it looks like another 50 to 60 knot jet streak moves
over the state. The GFS is warm with 850 mb temperatures around 16c.
However, the European model (ecmwf) is dry in the middle to upper levels (700-500 mb
layer rh<20%) and we weakly cold advect at the surface. Will go with the
chance of thunder for now.

&&

Aviation...(for the 18z tafs through 18z Thursday afternoon)
issued at 145 PM EDT Wednesday Aug 27 2014

Weak short wave continues to move away from the region leaving
instability driven cumulus clouds (but still VFR cigs). These
clouds will quickly dissipate later this afternoon as surface high
pressure builds in. Meanwhile...somewhat gusty northwest winds
will diminish early this evening. So mainly clear skies and calm
winds expected tonight. Lake breezes with just a few clouds
expected to develop Thursday. Bottom line...no weather issues through the
taf period.

&&

Marine...
issued at 1257 am EDT Wednesday Aug 27 2014

Incoming disturbance aloft will tighten the pressure gradient a bit
across Northern Lake Huron/straits for gusts to 20 knots today...but
incoming surface high pressure will bring winds down more significantly
heading into tonight. This high pressure lingers through Thursday
before winds turn more southeast/south Friday in advance of weak low
pressure and a warm front. This will spread rain across a good
portion of the nearshores Friday-Saturday night...exiting Sunday. No
wind concerns over this time frame.



&&

Apx watches/warnings/advisories...
Michigan...none.
LH...none.
Lm...none.
Ls...none.

&&

$$

Synopsis...smd
short term...smd
long term...jl
aviation...as
marine...smd

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