Area Forecast Discussion
Issued by NWS Gaylord, MI

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305
FXUS63 KAPX 241709
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
109 PM EDT Mon Jul 24 2017

.UPDATE...
Issued at 1009 AM EDT Mon Jul 24 2017

Strong high pressure continues to build into the Western Great
Lakes region late this morning in the wake of low pressure moving
toward New England. Weakening cyclonic flow lingering back over
Michigan is still producing some low level cloud cover across
portions of Lower Michigan...but this residual cloud cover is
quickly dissipating/moving out giving way to strengthening
subsidence and low level drying. This diminishing cloud trend will
continue from NW to SE during the afternoon...with our entire CWA
becoming mostly sunny by late afternoon. With ongoing CAA...high
temps will only reach into the lower 70s with noticeably less
humid conditions.

&&

.NEAR TERM...(Today through Tonight)
Issued at 329 AM EDT Mon Jul 24 2017

...Dry weather returns to start the work week...

High Impact Weather Potential...none.

Pattern Synopsis/Forecast...Overnight upper air/satellite/surface
map analysis reveals short wave trough axis working across Lake
Huron...attending surface low pressure in western New York state.
Deformation/wrap around cloud cover and some light precip
stretches up through southern Ontario/northern Lake Huron and
continues to skirt the far eastern reaches of NE lower Michigan
early this morning with -RA reported at APN for the last several
hours and drizzle and OSC. Outside of the light rain/drizzle...a
narrow corridor of stratus stretches across northern lower
Michigan and into Wisconsin. Dry air is pressing in from the
north...and has largely cleared out the upper peninsula.

Primary Forecast Concerns...minimal. Clearing trend today...lows
tonight.

Short wave trough will exit through the eastern lakes region today
replaced by upstream short wave ridging/surface high pressure
building into the upper Midwest this morning. Probably have
several more hours of very light rain/drizzle along the Lake
Huron shoreline...which should end by mid to late morning. Stratus
across northern lower Michigan will be slower...but eventually
high pressure/dry air/daytime heating and mixing will thin out the
clouds as we get into the afternoon.

Mainly clear and cool tonight with high pressure settling
overhead. Have lowered inherited forecast low temps a few
degrees...largely upper 40s to lower 50s with a few mid 40s for
the cold spots. But...wouldn`t be surprised to see a few low 40
degree readings Tuesday morning.

&&

.SHORT TERM...(Tuesday through Wednesday)
Issued at 329 AM EDT Mon Jul 24 2017

...Drying out, then Severe potential?...

High Impact Weather Potential...There is a chance for severe
thunderstorms on Wednesday.

Pattern Synopsis/Forecast...High pressure will continue its
dominance over the Upper Great Lakes for one more day. However, it
will begin its slide to the east during the day, which allows the
next system to push into the region overnight. It doesn`t look like
rain gets into the forecast area, until 09z/Wed as the cold front
moves over the Upper Peninsula. There is also a strong jet streak at
500 mb with 50+ knots that continues at least over 40 knots through
the day and in the RRQ. By 18z, the cold front and sfc trough is
just getting to W Lake Superior with the thunderstorms moving into E
Upper. The front continues south and east, with the expectation that
the warm, moist air will be out in front adding to the instability
through the afternoon and early evening. Wednesday night, the front
continues south out of the forecast area.

Primary Forecast concerns...There is a small concern with the min RH
on Tuesday, as it is currently progged to fall into the lower to mid
30% range for the afternoon, would fall below 30%. That would be an
elevated fire danger situation, although not a major one as the we
do not get below the critical threshold for the RH.

The other concern is the severe potential. Looking at the GFS
soundings the CAPE and Shear look marginal. Also, even though the
storms move through in the afternoon, sounding look like they have a
rather deep moisture layer that would indicate cloud cover. This may
be a limiting factor for the instability. So have moderate
confidence that severe weather is possible.

.LONG TERM...(Wednesday night through Sunday)
Issued at 329 AM EDT Mon Jul 24 2017

...High pressure looks to dominate the next week...

High Impact Weather Potential...Elevated fire weather conditions
possible for Friday, Saturday, and Sunday but that is probably a low
chance probability.

Extended (Thursday through Sunday)... High pressure builds into the
Upper Great Lakes, during the day on Thursday, forcing the showers
out of the region by the end of the day. Then for Friday through
Sunday, High pressure dominates keeping the afternoons dry and warm
with the high temperatures running around normal(upper 70s to lower
80s) through the weekend. The GFS has a weak cold front that moves
in to produce showers Sunday, but the other models don`t so will
continue with the dry forecast for now.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 109 PM EDT Mon Jul 24 2017

VFR conditions are expected at all Northern Lower Michigan TAF
sites through Tuesday as strong high pressure and dry air thru the
column remain overhead. Northerly winds at 10 to 15 kts will
become light/calm tonight...and then become southerly on Tuesday
AOB 10 kts.

&&

.MARINE...
Issued at 329 AM EDT Mon Jul 24 2017

A period of stronger NE winds will be felt on the lakes this
morning and into the afternoon...particularly on the Lake Huron
side. Winds will diminish through the day however...and become
light tonight through Tuesday. Winds will increase from the south
Tuesday night in advance of our next weather system for midweek.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...BEACH HAZARDS STATEMENT until 5 PM EDT this afternoon for MIZ018-
     024-030-036-042.
LH...SMALL CRAFT ADVISORY until 5 PM EDT this afternoon for LHZ348-
     349.
LM...SMALL CRAFT ADVISORY until 5 PM EDT this afternoon for LMZ323-
     344>346.
LS...NONE.
&&

$$

UPDATE...MR
NEAR TERM...BA
SHORT TERM...JL
LONG TERM...JL
AVIATION...MR
MARINE...BA



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