Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 192329
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
729 PM EDT MON SEP 19 2016

.SHORT TERM...(This evening and overnight)
Issued at 411 PM EDT Mon Sep 19 2016

Near term:

High impact weather potential: Marginal risk for severe
thunderstorms into this evening across much of northern lower.

Pattern synopsis and forecast:

A cold front is pushing into the region with its associated
showers and storms, developed at peak heating within a narrow
corridor of better low level moisture (dew points in the low to
mid 60s). Also helping were steep lapse rates aloft and and some
now analyzed pockets of upper divergence under a 120+kt jet.
Further upstream, much drier air is seen working across Lake
Superior and nrn WI, were skies have quickly cleared.

This forcing will be crossing us a bit more quickly that
previously thought with all storms weakening and likely
dissipating into the evening. Scattered light rains will drift
across eastern upper Michigan as they are out of the threat for
thunder. The storms have in fact, not been as strong, despite
modest instability of 500 to 750j/kg and 0-6km bulk shear of near
50kts. This was thought to possibly tap 50kt winds in the mid
levels for a marginal risk of damaging winds, but that hasn`t
happened at this point.

The skies will clear pretty quickly through the night with the much
drier air settling in more quickly as well. This dry air will
stick around through Tuesday with only some possible cirrus later
in the day.

Lows tonight in the mid 50s most locales and highs through the 70s
Tuesday.

.LONG TERM...(Tuesday through Monday)
Issued at 411 PM EDT Mon Sep 19 2016

High Impact Weather: heavy rain possible, but not likely Wednesday
night into Thursday.

(9/20)Tuesday night...High pressure begins to move east allowing the
return flow to begin and the warm front and moisture pooling along
it to move into Lower Michigan. At the same time, there is a 70 knot
jet core in Lake Superior with the RRQ going into E Upper by 12z. At
this point it looks fairly dry in the lower part of the model
soundings. So will continue the dry weather through the night.

(9/21)Wednesday...the models begin to moisten the mid levels, on the
soundings, especially around 850 mb and from about 600 mb and up.
This begins to allow the chances of rain to start, and increase
through the day, especially in E Upper. The GFS is much farther
south than the ECMWF with the same basic solution, but moves north
to the ECMWF idea by the evening, while the ECWMF brings rain south.
The main concern is that there could be training echoes along the
warm front as the winds from 850 mb through almost 400mb are uniform
in speed, and unidirectional through 300 mb. The PWs are around
1.5"+ through the night as well. So will have to watch this closely.
While while it is possible, again this isn`t a the most likely idea
so will go with a good steady rain, with embedded thunder
occasionally.

(9/22)Thursday...The rain continues into the day along the fast 500
mb flow and the warm front that is hung up around the Straits.
Although, the rain chances should begin to lessen as the warm front
begins to move north, and the drier air in the warm sector begins to
move into the forecast area.

As said before, will need to watch this one as we get closer to the
day. This has a sneaky look to it, but the confidence level is low
at this point for getting anything that would cause any flood
issues. This could just turn into a system that moved into the
region a few weeks ago, and didn`t do much in the way of rain, even
with record PWs for N MI.

JSL

Friday through Monday

Models agree on a broad area of troughiness over the Great Lakes
region with a narrow ribbon of deeper moisture running west to east
across the northern Great Lakes. However, they differ on timing with
a large area of surface high pressure and accompanied dry air
pushing precipitation chances south. The GFS has the dry air over
all of northern Michigan for much of Saturday and through early
Sunday afternoon, while the ECMWF has only eastern upper and
portions of northeast lower precipitation-free through early Sunday.
Regardless of which scenario plays out, a low pressure system
develops over the northern Plains, increasing cloudiness Sunday
afternoon and then returning precipitation chances late Sunday
through Monday as said system deepens as it moves over the northern
Great Lakes region. Highs will be in the mid to upper 60s (still a
bit above average for this time of the year), while overnight lows
will generally be in the mid to upper 40s.

TJL

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 729 PM EDT Mon Sep 19 2016

Showers ending this evening, then VFR.

A cold front is crossing northern lower MI this evening.
Associated shower activity will move off to the east and/or
diminish over the next several hours. Quiet wx after that, as high
pressure builds into the central/southern lakes region by Tuesday
morning.

Current sw winds will become light westerly tonight, and a bit
gusty from the west on Tuesday.

&&

.MARINE...
Issued at 411 PM EDT Mon Sep 19 2016

Scattered showers and thunderstorms along a cold front will cross
the region this evening and gusty advisory level winds will taper
off. The gradient picks back up again as winds shift more out of
the west later tonight. Advisories have been extended into Tuesday
for many of the northern nearshore waters, before higher pressure
weakens the gradient from south to north through the day. The
weaker gradient holds in place while a developing system brings a
potential extended period of rain from late Wednesday into Friday.


&&

.APX Watches/Warnings/Advisories...
MI...NONE.
LH...SMALL CRAFT ADVISORY until 5 PM EDT Tuesday for LHZ345>347.

     SMALL CRAFT ADVISORY until 5 AM EDT Tuesday for LHZ348-349.

LM...SMALL CRAFT ADVISORY until 5 PM EDT Tuesday for LMZ341-342.

     SMALL CRAFT ADVISORY until 5 AM EDT Tuesday for LMZ323-344>346.

LS...SMALL CRAFT ADVISORY until 5 PM EDT Tuesday for LSZ321-322.

&&

$$

SHORT TERM...Dickson
LONG TERM...JSL/TJL
AVIATION...JZ
MARINE...Dickson



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