Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 171912
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
312 PM EDT Mon Apr 17 2017

.NEAR TERM...(Tonight through Tuesday)
Issued at 311 PM EDT Mon Apr 17 2017

High impact weather potential: None.

Pattern synopsis and forecast:

Pretty quiet out there this afternoon. A nearly stationary frontal
boundary has sunk down into far srn lower Michigan, shoved by fairly
light northerly winds on the srn flank of strong high pressure over
James Bay. The flow aloft remains pretty fast, with one shallow and
positively tilted shortwave now crossing nrn Michigan. Forcing was
very weak, but there has been some low to mid level moisture
available for DPVA to squeeze out some very light rain/sprinkles
across nrn lower Michigan. Skies were pretty cloudy everywhere, with
thicker stratus taking a lot longer to mix out north of M-68,
including eastern upper, More mid level clouds were associated areas
south of M-68. There is some downsloping winds out of Ontario, as
well as drier air filtering into eastern upper, and those clouds
were mixing out/dissipating. Temperatures were in the cool mid 30s
where the low clouds are/were, and in the 40s elsewhere.

See no reason why the clouds won`t just keep clearing out across
eastern upper, with the drying feeding southward into nrn lower by
late this afternoon/early evening. Meanwhile the aforementioned
shallow wave aloft will depart by early evening, ending all
sprinkles/light rain. Skies then expected to clear out to a large
degree tonight. This ought to allow temperatures to get pretty
chilly by daybreak. Most guidance kept readings in the lower 30s,
but that 5 degree drop in clear skies and light winds doesn`t make
much sense. The Canadian data suggestion is for lower 20s in many
areas of eastern upper and far nrn lower, with mid 20s to lower 30s
elsewhere in nrn lower. Sided with that data for the minimum
temperatures. These cooler readings are expected, despite sfc ridge
axis heading east and developing a southerly flow overnight.

This southerly flow increases through the day Tuesday, out ahead of
the next approaching low pressure system that will make it into far
western Lake Superior by early Tuesday evening. This will also drive
a warm front into Lake Michigan with moisture advection increasing
on the nose of a fairly potent 45-55kt LLJ. Nice little pocket of
deep layer -divQ seen, but the actual moisture availability isn`t
too great. This ought to be sufficient enough however, to bring
scattered shower activity into Lake Michigan and eastern upper.
possibly scraping NW lower by nightfall. Lapse rates aloft are not
very steep and any form of CAPE is nil. Thunder not to be mentioned.
Highs Tuesday in the low 50s eastern upper to as warm as the low to
mid 60s in the GTV Bay region and along M-55.

&&

.SHORT TERM...(Tuesday night through Thursday)
Issued at 311 PM EDT Mon Apr 17 2017

High Impact Weather Potential...Showers and thunderstorms will be
possible for Tuesday night into Thursday.

Pattern Synopsis/Forecast...Flat 500 mb flow pushes the sfc low
quickly to the east so that by 06z, rain should be ending shortly
after that. The speed max is fairly strong (70+ kts) and has quite
the subsidence in its wake as it moves east with the sfc low. This
allows the day on Wednesday to be dry as sfc high pressure builds
into the N lower, as well as a rise in the 500 mb heights up to
00z/Thu. The next sfc low/500 mb shortwave trough moves into the
Upper Great Lakes after 00z/Thu and begins to move rain into the
region by 06z. GFS has slowed that rain down a bit with the rain
only to the Lake Michigan counties by 06z, and the ECMWF/00 and 12z
showing rain across the entire forecast area. The GFS has rain
across the region by 12z/Thu. The sfc low then cuts across C Lower
Michigan and brings rain to the region through the day.

Primary Forecast Concerns...Will there be heavy rain again. Looking
at the GEFS and SREF plumes for QPF, The best and heaviest rain is
looking like it will be along and south of the M-55 corridor, as the
warm front stalls and the sfc low moves across the state roughly
along that track. The spread of QPF is grouped closest to the mean
which is around 1.00". This could produce issues along the Rifle and
Manistee rivers where they are already running high from the
previous heavy rain from the other day.

&&

.LONG TERM...(Thursday night through Monday)
Issued at 311 PM EDT Mon Apr 17 2017

A departing low pressure system over the western Great Lakes will
continue to generate precip with wrap around moisture, this precip
may then possibly change to a rain/snow mix or even to all snow for
some locales Thursday night into Friday morning as colder air
filters in behind said system. High pressure centered over Hudson
Bay then ridges into the Great Lakes region diminishing cloud cover
and ending any lingering showers throughout the day Friday with
temperatures moderating a bit, reaching into the low to mid 50s
throughout the remainder of the week. Long range models are in good
agreement at another storm system developing on the lee side of the
Rockies, but moving south of the forecast area, with only a possible
grazing of our southern forecast area. This scenario would provide
for nearly precipitation-free weather Friday afternoon and through
the entire extended period.

Low temperatures will be in the 30s.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 645 AM EDT Mon Apr 17 2017

Low MVFR stratus will gradually lift to low VFR cigs by early
afternoon thanks to diurnal mixing. A few showers may develop this
afternoon along and south of M-32 and east of US-131 as daytime
instability begins to interact with a weak moisture-starved trough
slides thru the area today. Skies will clear tonight as high
pressure builds into the region. Winds will be from the N/NW AOB
10 kts thru today and then become light/variable tonight.


&&

.MARINE...
Issued at 311 PM EDT Mon Apr 17 2017

A light northerly/variable flow will gradually turn out of the SE
overnight as a ridge of sfc high pressure departs east. This S/SE
wind increases through Tuesday, remaining pretty swift just above
the water sfc into Thursday night while turning more S/SW with the
passage of a warm front. Despite growing overlake instability, low
end advisory level gusts are expected, along with increasing chances
for seeing showers roll across the Great Lakes Thursday night as the
system cold front pushes through. This will also shift winds out of
the NW into Wednesday morning. Stability will be decreasing in the
cold air advection, but winds do not appear strong enough attm for
any significant advisory level speeds.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...SMALL CRAFT ADVISORY from 8 AM Tuesday to 2 AM EDT Wednesday for
     LHZ345>349.
LM...SMALL CRAFT ADVISORY from 8 AM Tuesday to 2 AM EDT Wednesday for
     LMZ323-341-342-344>346.
LS...SMALL CRAFT ADVISORY from 8 AM Tuesday to 2 AM EDT Wednesday for
     LSZ321-322.
&&

$$

NEAR TERM...SMD
SHORT TERM...JSL
LONG TERM...TJL
AVIATION...MLR
MARINE...SMD



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