Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 310329
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
1129 PM EDT SAT JUL 30 2016

.UPDATE...
Issued at 1044 PM EDT Sat Jul 30 2016

Pesky low level circulation remains across southern lower
Michigan into Ohio with an associated deformation axis cutting
across southern/central lower Michigan. Small scale embedded wave
has been swinging northward up through the thumb this evening and
pushing an enhanced batch of showers through Saginaw Bay and now
skirting the Huron coast around Standish/Au Gres and Tawas.

Rest of tonight: Precip chances and coverage are the biggest
forecast challenge. Small scale embedded wave looking to drift
northward along the Huron coast over the next few hours and will
bring some rain to the far SE/E counties. Lower levels of the
atmosphere currently remain on the drier side which may limit
coverage/amounts, although weak winds/slow moving showers could
lead to some localized decent amounts. But I have nudged up pops
over that part of the CWA. Meanwhile, aforementioned circulation
over southern lower Michigan will tighten up a bit and migrate
northeastward into the Saginaw Bay area by morning, pushing
deformation axis up into northern lower Michigan. Suspect we may
see additional showers expand up into northern lower Michigan
later tonight into Sunday and I have expanded pops accordingly.

Precip amounts are another matter. A bit disconcerting that recent
NAM guidance runs have continued to develop some rather strong
low level convergence and resulting slow moving showers/heftier
QPF bullseyes up into interior northern lower Michigan overnight
into Sunday. Something that we have certainly seen from this pesky
system further south over the last few days. It remains to be
seen whether or not that will actually occur as our airmass this
far north is not nearly as moist as downstate, although PWATS
will be increasing heading into Sunday. But we will have to remain
vigilant for any sneaky heavy rainfall over the next 12 to 18 hours
or so.

&&

.SHORT TERM...(This evening and overnight)
Issued at 326 PM EDT Sat Jul 30 2016

High impact weather potential: Minimal.

Pattern synopsis/expected evolution: Kinda a convoluted mid level
pattern out there early this afternoon, with a multiple of low
amplitude waves embedded in what otherwise is broad Great Lakes
centered troughing. Area of deformation tied to one such wave has
been kicking off bands of slow moving showers and thunderstorms
across southern Michigan, some of which have produced locally very
heavy rainfall. Some of this moisture is making a slow, but
steady, move north, with mainly cloudy skies now found along and
south of the M-55 corridor. Mostly to partly sunny skies are the
rule across the remainder of the area, made that way by dry east
flow rotating around high pressure centered just to our northeast.

Some subtle changes to occur overnight, with that southern Michigan
wave rotating northeast into Lake Huron by Sunday morning, all-the-
while a more subtle and much more moisture starved wave pivots into
northern Lake Michigan. Not much at all expected with the latter,
while the former looks to bring at least some shower threat to parts
of northeast lower Michigan.

Primary forecast concerns/challenges: Cloud trends and light shower
evolution tonight.

Details: Per simple satellite trends and low/mid level moisture
analysis, expect clouds to continue to rotate north, with much of
northern lower Michigan likely becoming mostly cloudy by morning.
Aggressive dry air feed expected to continue for our friends north
of the big bridge, keeping them mainly clear. As mentioned, that
southern wave and attendant weak deformation axis slides northeast,
impacting northeast lower through the overnight. Forcing is
limited, and deep layer moisture profiles remain disjointed.
Instability is also nearly non-existent, with limited lapse rates
through the mid- levels. Now, with all that said, do expect some
light showers to rotate slow northeast, cutting across northeast
lower (likely remaining east of US-27). Overall coverage should
remain limited, with rainfall amounts remaining generally light.

Those increasing clouds will keep temperatures a few degrees
warmer than those observed this past morning, with overnight lows
ranging from the middle 50s to lower 60s.

.LONG TERM...(Sunday through Saturday)
Issued at 326 PM EDT Sat Jul 30 2016

IMPACTS: Minimal through mid-week

PATTERN SYNOPSIS/EXPECTED EVOLUTION: (Sunday through Tuesday) Sunday
morning, split flow continues from WI through Ontario with ridging
building in the SW dampened by a cutoff moving through British
Columbia/Alberta. A stationary front spans across much of the CONUS,
with broad surface high pressure from the Great Lakes through New
England. Shortwave ridging will build through mid-week, ahead of the
cutoff low moving through Canada.

MAIN FORECAST CHALLENGES/CONCERNS: Pretty quiet through Tuesday.
Issues with moisture availability for shower chances Sunday.

ASSOCIATED WEATHER:

Sunday...As high pressure builds in, the pressure gradient will
weaken resulting in lighter winds. This should help in lake breeze
development off Lake Michigan in the afternoon. Have been wondering
if any shower development would take place along the lake breeze
boundary. Recent GFS runs seem to be favoring some precip on the
west side of the state. Thinking that it may be a bit aggressive
with moisture and too quick to saturate. Starting to see hints of
the moisture sticking around in previously drier guidance as well
however. Will continue with scattered showers early in the morning
in the SE portion of CWA where best moisture resides, but add the
chance for some scattered showers on the west side of the state as
there may just be enough moisture for the afternoon heating and lake
breeze boundary to force a few showers. Temperatures will run near
to slightly above normal as the height rises just begin to build
into the area.

Monday and Tuesday...Height rises will continue to build over the
region as the shortwave ridging moves in from the west. With surface
high pressure still present and the H5 ridge folding overhead, both
days should remain precip free. Temperatures will continue to warm
both days, climbing through the 80s with some areas seeing mid and
upper 80s on Tuesday.

ALM

Extended: (Tuesday night through Saturday)

The extended period will begin with a cold front associated with a
low pressure system over Hudson Bay passing through the Great Lakes
region. This cold front along with some return flow ahead of it will
provide chances of rain and thunder Tuesday night through Wednesday.
Models differ on timing of the next system and accompanying upper-
level troughing Thursday. Could be dry most of the day Thursday or
precipitation begins early Thursday afternoon...depending on which
model you look at. After Thursday evening though...the models are in
fairly good agreement that troughing will remain over the region,
with several shortwaves and ample moisture to develop periods of
rain and thunder throughout the remaining period. Although pops are
in every day of the extended forecast, by no means will it be a
washout. There will be partly to mostly cloudy skies with periods of
rain/thunder here and there throughout the period. Daytime
temperatures will warm into the 80s and even reaching in the low 90s
Thursday, while the nights will remain warm and humid, only dropping
into the mid to upper 60s.

TJL

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1129 PM EDT Sat Jul 30 2016

...A period of MVFR cigs overnight into Sunday...

Very slow moving weak low pressure system over Ohio will push
cloud cover and some showers up into northern lower Michigan
tonight through Sunday. Cigs will lower to low VFR tonight and
possibly into the MVFR category at TVC/MBL late overnight through
Sunday morning. APN/PLN should remain VFR. Cloud cover will slowly
thin and lift Sunday afternoon back to VFR conditions by late in
the day.

Light easterly winds will increase to near 10 knots again on
Sunday.

&&

.MARINE...
Issued at 326 PM EDT Sat Jul 30 2016

Marginally gusty east to northeast winds will continue into
the overnight. East to northeast wind continue through Sunday,
decreasing some heading through the day. Pressure gradient becomes
just light enough to perhaps allow localized lake breeze development
by Sunday afternoon. Light winds are expected to persist through the
beginning of the work week.


&&

.APX Watches/Warnings/Advisories...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&

$$

UPDATE...Adam
SHORT TERM...MSB
LONG TERM...TJL/Mayhew
AVIATION...Adam
MARINE...MSB



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