Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 270123
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
923 PM EDT Mon Sep 26 2016

.UPDATE...
Issued at 923 PM EDT Mon Sep 26 2016

Blustery and damp night in the w to wsw lake effect belts. There
will be relative upticks and lulls in shower activity as vort
maxes come thru. However, there isn`t much of a lull between the
current uptick and the next one seen just east of ESC. The above
notwithstanding, conditions will be rather steady-state tonight.
Winds will diminish just a touch during the overnight, as the
surface low nearing far northern Superior fills a couple of mb.

Have been a few lightning strikes downstate and over Lake Huron
this evening. Anticipate steepening lapse rates as the stacked low
edges closer, and will maintain a slight chance of thunder where
pops are highest.

&&

.SHORT TERM...(This evening and overnight)
Issued at 311 PM EDT Mon Sep 26 2016

High impact weather potential: A few thunderstorms possible
through Tuesday. No severe weather. Waterspout potential increasing
tonight into Tuesday.

Pattern synopsis and forecast:

Sfc low pressure spinning in Ontario underneath it`s parent cut off
upper low. Cold advection has been well underway via strong/gusty
SW/WSW winds. Air temperatures over the Great Lakes has become cold
enough for the rapid development of lake effect rain showers. The
advection of deeper lower level moisture from Wisconsin has allowed
these showers to expand in coverage across a good chunk of NW lower,
as well as some more spottier light showers into the higher terrain
of interior lower. Well away from the lake effect flow regimes,
nearer to Saginaw Bay, there has been at least some breaks in the
overcast. Temperatures are quite cool with readings in the middle
50s to lower 60s.

The upper level low pressure will slowly spin southward through
Tuesday, advecting deeper and deeper moisture into nrn Michigan
while air temperatures over the Great Lakes remain +3 to +4C. The
deeper moisture and forcing tied more so to several individual
vorticity maxima wrapping in overhead. Bottom line, periods of showers
can be expected, and without question, this will more so be the case
in the SW/WSW flow regimes for which the 1000-850mb winds remain
fairly locked. Convective cloud depths over the Great Lakes will
vary over time, but will be more than sufficient for the chance for
waterspouts. Lake generated instability shows 200-600j/kg of CAPE
extending into the mid levels for at least the possibility of a
rumble of thunder in some of the better/stronger showers. Windy,
damp and raw in the showers with less gustiness Tuesday.

Temperatures will not swing too much, no more than 10 degrees for
most locales. Lows in the upper 40s to lower 50s tonight and an even
cooler day tomorrow in the middle 50s to lower 60s.

.LONG TERM...(Tuesday through Monday)
Issued at 311 PM EDT Mon Sep 26 2016

High impact weather potential: Slight chance of thunder Tuesday
night.

Pattern synopsis/Expected evolution: Northern Michigan`s sensible
weather over the next 5-7 days hinges on an upper-level low clearly
visible on water vapor imagery spinning near the the Arrowhead of
Minnesota this afternoon. As ridging builds off the East Coast, said
upper level low will drop south over the Great lakes early this
week, into the Ohio Valley by mid-late week, and then is expected to
retrograde back north toward the state of Michigan once again next
week. As a result, a rather unsettled period of weather is expected
with near to slightly cooler than normal temperatures, generally
lots of clouds, and occasional showery periods.

Tue night - Wednesday: Numerous rain showers are expected to
continue Tuesday night as our closed upper low treks from near Green
Bay to Chicago overnight. Despite an unfavorable low-level wind
pattern as the low sinks off to our southwest, over-lake instability
should be ample with delta Ts around 16 C, aiding to promote
additional lake-driven showers (especially across eastern areas).
Wouldn`t be shocked if a couple rumbles of thunder across the area
continued Tue night, but a lack of instability should limit the
convective coverage. As Wednesday wears on, shower coverage is
expected to diminish as the system continues its southern trend,
becoming centered near Indianapolis by Wed evening. Will continue to
carry the highest PoPs south of M-72 on Wednesday, tapering north.
Overall, a fall-like day with highs topping out in the upper 50s to
low 60s area-wide.

Wednesday night - Thursday: Fairly decent model consensus through
the end of the period with the closed circulation centered over the
Ohio River Valley on Thursday. With lingering spokes of moisture
pinwheeling around the periphery of the low, will continue slight
chance PoPs through Thursday, mainly along and east of I-75. With an
ENE fetch across Lake Huron and delta Ts toeing the proverbial 13 C
line, wouldn`t be all too shocked to see the best shower coverage
across eastern/southeastern zones, so at this point will hedge the
highest PoPs in that direction.

MG

Models are all in pretty good agreement with keeping a pesky cutoff
upper level low bobbing over the area through the extended period.
The low sinks as far south as the Ohio river on Friday...but nearly
all solutions show it retrograding back north by Sunday. Should this
occur...we can kiss any hopes of clearing/drying for the weekend
goodbye. By Monday, hopes are the low will begin to fill in and edge
eastward...leaving Monday as possibly the only day we see some
sunshine begin to break through.  But that`s a long way off yet.
Temperatures through the extended period are shaping up to run right
along with climo.

KAB

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 734 PM EDT Mon Sep 26 2016

Mainly VFR, but MVFR at times in SHRA.

Low pressure just north of Superior will continue to bring cool
and relatively moist air into the region. Lake effect clouds and
rain showers will persist in nw lower thru this forecast. VFR
conditions will still prevail most of the time, but TVC/MBL and
especially PLN could dip into MVFR territory briefly (at just
about any time).

Ongoing gusty sw to w winds will diminish slightly tonight and
Tuesday.


&&

.MARINE...
Issued at 311 PM EDT Mon Sep 26 2016

Cold air advection has blasted into the Great Lakes via strong and
gusty SW/WSW winds after a cold frontal passage. Very unstable
overlake conditions are now present, and lake effect rain showers
have developed. These showers will further expand in coverage and
intensity through Tuesday night as deeper moisture and an upper low
slowly move overhead. The upper low may exit far enough south late
this work week for somewhat better conditions out there, but the
idea is for this low to come right back overhead, or close by, this
weekend for similar dreary conditions

Gale force wind gusts across much of the NW lower nearshore waters
will gradually fade through the late night hours, and remain in
advisory speeds for Tuesday in almost all waters.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...SMALL CRAFT ADVISORY until 6 PM EDT Tuesday for LHZ345>349.

LM...SMALL CRAFT ADVISORY until 6 PM EDT Tuesday for LMZ341.

     GALE WARNING until 5 AM EDT Tuesday for LMZ323-342-344>346.

LS...SMALL CRAFT ADVISORY until 6 PM EDT Tuesday for LSZ321-322.

&&

$$

UPDATE...JZ
SHORT TERM...Dickson
LONG TERM...Gillen/KAB
AVIATION...JZ
MARINE...Dickson



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