Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 232300
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
700 PM EDT Wed Aug 23 2017

.NEAR TERM...(Tonight through Thursday)
Issued at 249 PM EDT Wed Aug 23 2017

...Unseasonably Cool Temperatures Continue...

High Impact Weather Potential:  Minimal

Pattern Forecast: Deepening short wave trough/closed low spinning
across northeast Ontario and the adjacent Great Lakes...with
northern Michigan to the cool side of the polar jet axis. Pieces of
shortwave energy continue to pinwheel around parent upper low.

Another weak shortwave sliding across northern/eastern parts of the
area late this afternoon, possibly producing a few sprinkles or
light showers.  Drier air arrives this evening, with another surge
of moisture and renewed cold air advection kicking in toward
Thursday morning with the arrival of another shortwave trough. Low
level flow will gradually veer more northerly with time, possibly
bringing some lake induced sprinkles/light showers to coastal Lake
Michigan and Lake Huron.  We will likely keep enough of a gradient
with surface high still well upstream to prevent temperatures from
really bottoming out. Nevertheless, a fairly chilly night with
widespread lows in the 40s.  Will keep Lake Michigan beach hazards
going through early evening due mainly to residual wave
action.

Another shortwave slides southward through the base of the upper
trough on Thursday, bringing with it another uptick in mid level
moisture and possibly a few sprinkles/light showers.  Plenty of over-
lake instability still in place, but low level flow will be mainly
north, which is not a terribly good direction for much lake effect
induced precipitation across northern Michigan. Morning clouds
will give way to at least partial sunshine as any lake processes
become diurnally disrupted and some of the mid level moisture with
the shortwave mixes out. 850mb thermal trough positioned across
northern Michigan resulting in another unusually cool August day -
widespread highs in the 60s with a few readings near 70 closer to
Saginaw Bay. The gradient will be weaker and winds should be
lighter as high pressure nudges closer to the Great Lakes.

&&

.SHORT TERM...(Thursday night through Saturday)
Issued at 249 PM EDT Wed Aug 23 2017

...Days slowly getting warmer but nights are still chilly...

High impact weather potential...patchy frost Thu night in usual
cold spots of interior northern lower MI.

Large/cool high pressure will set up shop over MI to end the work
week and start the weekend. This will keep our wx very quiet...with
one exception (below). Cloud cover will be minimal thru most of this
period. Perhaps some lingering cu/altocu remnants in southern
sections to start Thu evening. Also perhaps some mid/high clouds
from warm advection upstream drifting into western sections late
Saturday. Otherwise, a cool/dry airmass in place, with no precip
threats, light winds, and large diurnal temp swings. Pretty nice
days, all things considered.

The one wx possibility is frost. Guidance has been trending slowly
cooler. The usual interior cold spots (GOV/PLN) are now seeing some
mid 30s from the MET/MAV numbers Thu night (and not much better Fri
night). This is likely better guidance than the national model
blend, which simply doesn`t go cold enough on nights like these.
Will push the forecast closer to MOS numbers in northern lower MI.
This necessitates adding patchy frost to the grids in the usual
coldest locales of northern lower MI. Given this is a little early
for this sort of thing, will also add a frost mention to the HWO.

Min temps mid 30s to mid 40s. Max temps around 70f Fri, another 2-4f
warmer Sat.

.LONG TERM...(Saturday night through Wednesday)
Issued at 249 PM EDT Wed Aug 23 2017

Although high pressure will be over the Great Lakes region, an upper
level disturbance just to the west will usher in associated moisture
that could trigger mostly diurnal showers each day of the week.
There is low confidence, especially the second half of this period,
as models are drastically different...possibly the tropical storm in
the Gulf messing up the progressive pattern as the models slow down
the upper level trough and even develop a cut-off low over the
western Great Lakes region. Have a feeling the long term forecast
will be changing from day to day quite a bit. Daytime temperatures
will be in the low 70s Sunday and then moderate a bit each day until
we hit the mid to upper 70s by Tuesday. Lows will be in the mid 40s
to low 50s Sunday morning and then warm into the 50s for the
remainder of the period.

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 700 PM EDT Wed Aug 23 2017

Lingering cyclonic flow...wrap-around low level moisture and
over-lake instability will continue to produce sct/bkn lake
enhanced low VFR clouds across Northern Michigan tonight into
Thursday. N/NW winds will remain AOB 10 kts thru the forecast
period.

&&

.MARINE...
Issued at 249 PM EDT Wed Aug 23 2017

Winds gradually subside tonight as high pressure moves closer to the
area.  Lake effect clouds/isolated showers possible closer to the
coasts as flow veers more northerly.  A slightly chance of a
waterspout late tonight into early Thursday, especially Northern
Lake Huron.  High pressure will bring much lighter winds and
eventually warmer temperatures for the end of the week into the
weekend.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...BEACH HAZARDS STATEMENT until 8 PM EDT this evening for MIZ016-
     019>021-025-031.
LH...SMALL CRAFT ADVISORY until 8 PM EDT this evening for LHZ345>349.
LM...SMALL CRAFT ADVISORY until 8 PM EDT this evening for LMZ323-341-
     342-344>346.
LS...SMALL CRAFT ADVISORY until 8 PM EDT this evening for LSZ321-322.
&&

$$

NEAR TERM...JK
SHORT TERM...JZ
LONG TERM...TL
AVIATION...MR
MARINE...JK



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