Area Forecast Discussion
Issued by NWS Gaylord, MI

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385
FXUS63 KAPX 191035
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
635 AM EDT Sat Aug 19 2017

.NEAR TERM...(Today through Tonight)
Issued at 245 AM EDT Sat Aug 19 2017

High impact weather potential: A thunderstorm in lake breeze
convergence today?

Pattern synopsis and forecast:

Upper level troughing was directly overhead early this morning,
while more pronounced ridging was over the nrn plains. At the sfc,
low pressure was in western Quebec and was continuing to track east,
but low level cyclonic convergence/sfc troughing was still stubborn
to depart. This has resulted in a prolonged period of low level
clouds and spits of light rain across nrn Michigan. In addition, mid
and upper level clouds were also pushing into the region, associated
with the upper level troughing. All this cloud has kept temperatures
from falling, remaining in the upper 50s to lower 60s most areas.

Not much going on in weather today through tonight. Can certainly
see mostly cloudy skies through at least a portion of the morning
hours past daybreak, as well as spits of light rain. With the
further eastward progression of the sfc low, passing upper trough,
and incoming higher pressure, skies will gradually allow some sun to
appear. Believe that low level moisture is still plenty enough to
result in a decent coverage of cumulus, especially in interior
eastern upper and far NE lower where lake breeze convergence is
expected. In addition, modifying RUC/GFS fcst soundings, 200-600j/kg
of MLCAPE is revealed. Can see maybe some isolated showers with an
outside shot at a weak/garden-variety thunderstorm in these areas.
Of course, we have to get the warming today from the sun.

Other showers may be able to drift down into NW lower this evening,
generated from lake breezes in far NE WI/central upper. Not much in
the way of help aloft in sustaining any precipitation, but there is
at least some indication of weak vorticity in the NW flow aloft.
Plus, the lakes are relatively warm with some BL instability holding
through evening. Otherwise, skies will decrease in clouds overnight,
with only some higher level cloud possible.

High today in the middle 70s most areas with lows in the upper 50s
and lower 60s tonight.

&&

.SHORT TERM...(Sunday through Monday)
Issued at 245 AM EDT Sat Aug 19 2017

High Impact Weather Potential: Minimal.

Pattern Forecast: Low amplitude ridging on Sunday gives way to
increasingly unsettled weather early next week with a frontal
boundary sliding into the Great Lakes.

Primary forecast challenge:  Shower and thunderstorm chances Sunday
night into Monday.

Fairly quiet weather during the daylight hours on Sunday with return
low level flow developing as high pressure slowly slides to the
southeast of the area.  This will push warmer H8 air into the Great
Lakes, with high temperatures into the 80s in many areas. Upstream
trough/frontal boundary sags toward the western lakes/upper Michigan
Sunday night. Moisture pooling in vicinity of the boundary, with
theta-e axis folding southward through upper Michigan and toward the
Straits. With modestly steep mid level lapse rates and increasing
amounts of deep layer moisture, showers/storms will become more
numerous over upper Michigan and northwest lower Michigan.

Front remains draped across northern lower Michigan on Monday (sorry
eclipse viewers), with plenty of clouds and scattered showers/storms
with additional ripples of shortwave energy riding along it.  A warm
and humid day, with dewpoints well into the 60s (possibly
approaching 70 degrees over southwest parts of the area).  Despite
the clouds/pcpn...temperatures still into the 80s in many areas.

Eclipse viewing forecast...Not very good for much of northern
Michigan with frontal boundary in the area bringing mostly cloudy
skies.  The best viewing in the state likely over southeast Michigan
where less clouds are expected.

.LONG TERM...(Monday night through Friday)
Issued at 245 AM EDT Sat Aug 19 2017

Frontal boundary and weak surface low will push through the Great
Lakes Monday night into Tuesday.  There are still some question
marks between the models as to the speed of the frontal boundary and
the strength of the surface reflection riding along it.  Will carry
high rain chances Monday night into Tuesday (especially northern
lower), with locally heavy rain a possibility given deep layer
moisture in place (PWATs nearing 2 inches).  Another shot of very
cool late summer air takes hold for the middle and end of the week.
There could even be some lows in the 30s in the typically cooler
locations for the end of the week under ideal radiational cooling
conditions.  A few showers still likely on Wednesday, with drier
conditions expected for the end of the week.

&&

.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 632 AM EDT Sat Aug 19 2017

Low pressure will track eastward from Quebec, further from nrn
Michigan. taking low level cyclonic flow and the deeper low level
moisture. Light rains have already ended and the MVFR CIGS are
lifting. Still expecting SCT-BKN cumulus today with slight chance
for a shower near/south of APN. There is also a chance for a few
showers to roll across Lake Michigan and into NW lower this
evening, possibly impacting mainly TVC. Skies clear to some
degree heading into tonight, but there will likely be some higher
level clouds at times.

Westerly winds generally under 10kts will tend to go more SW then
calm through the night.

&&

.MARINE...
Issued at 245 AM EDT Sat Aug 19 2017

Low pressure in western Quebec will press eastward today, being
replaced by higher pressure through tonight and into Sunday. A slow
moving cold front will then press into Lake Superior Sunday and
Sunday night. Remnant gusty westerly flow with some low end advisory
gusts through daybreak in and around Presque Isle Light, will
gradually swing around more southerly while weakening later today
and tonight. Light southerly flow increases through the day Sunday
and Sunday night, but no advisories expected at this time.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...SMALL CRAFT ADVISORY until 11 AM EDT this morning for LHZ347-348.
LM...NONE.
LS...NONE.
&&

$$

NEAR TERM...SMD
SHORT TERM...JK
LONG TERM...JK
AVIATION...SMD
MARINE...SMD



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