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000
FXUS63 KAPX 291915
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
315 PM EDT Thu Sep 29 2016

.SHORT TERM...(This evening and overnight)
Issued at 312 PM EDT Thu Sep 29 2016

Upper level low that has plagued Great Lakes weather for the last
few days continues to sit and spins across the lower Ohio Valley
this afternoon. Deep Atlantic moisture feed within warm conveyor
belt of this system bringing some decent rains to our neighbors to
our south, with rainfall amounts this morning in excess of 3 inches
for parts of southeast Michigan. Up this way, deep northeast flow
continues to bring in plenty of lower level dry air, which has
greatly hindered any northward advance of that southern Michigan
rain shield (and brought sun-filled skies to eastern upper
Michigan). Based off simple radar extrapolation, it does look like a
few light showers will impact areas down closer to Saginaw Bay yet
this afternoon.

Difficult rain forecast heading through tonight and Friday as that
upper level system only makes slow progress back north. That
Atlantic moisture plume attempts to do the same, although persistent
dry northeast flow will have plenty to say on just how far north it
advances. Pretty stout h8-h7 theta-e advection does occur overnight
into Friday over northern lower, although better forcing per passing
vort lobes rotating around parent system largely remains off to our
south. Given trends/simple persistence, gotta believe the better
rains stay to our south for the next 24 hours or so, waiting to make
a more definitive northward shift Friday night. Still do believe
some lighter activity will slide into parts of northern lower
tonight and Friday, especially along and south of the M-55 corridor.
Will trend inherited pops accordingly, with a rather sharp south to
north delineation. Now, with all that said, this will have to be
closely monitoried, as rainfall rates could be locally heavy with
efficient rain processes and definite hints of training shower
activity (see Detroit this morning). Current thought is this heavier
rain axis will remain just off to our south.

.LONG TERM...(Friday through Thursday)
Issued at 312 PM EDT Thu Sep 29 2016

Synoptic pattern: Vertically stacked upper low over the Ohio Valley
will meander its way northward through southern Michigan this
weekend under the influence of increasing westerlies.   This will
result in a rather cloudy and unsettled weekend, with periodic rain
chances.

Model guidance in very good agreement Friday night through the
weekend in lifting upper low northward into Michigan.  The
challenging part of the forecast is in the details of precipitation
associated with circulation center, as models continue to struggle
to resolve embedded shortwaves. Most widespread rain potential
Friday night should be across the southern half of the area (mainly
south of M-55) within H8-H7 theta-e axis, with lesser rain the
further the north you go where the influence of dry easterly flow
will be greater.

Plenty of question marks for the weekend with regard to how wet
things will be.  850mb theta-e ridge shifts north through the
weekend, but is not necessarily reflected in the model QPF.
Certainly some showers around on Saturday, although wonder whether
drier east flow will continue to influence the coverage of
precipitation.  Deeper moisture (H8-H5) pushes northward into more
of the area later Saturday night into Sunday as surface/upper
feature moves toward the Thumb region.  This may bring a better
chance of rain to more of the area - although confidence is not that
high.  Temperatures near seasonable levels, with highs generally in
the 60s.

JK

Monday through Thursday...will continue with well above normal
temperatures along with mainly dry conditions through the period.

At upper lvls...A nearly cutoff upper low over the ern lakes Sunday
night will exit east Monday...while a second upper low organizes and
digs into the west coast. A 500mb upper ridge will increase across
the Great Lakes and Ohio Valley through midweek...as the west coast
upper low pushes into the Plains. Mid lvl temps in this pattern...
show 850mb temps around 8c through Tuesday...warming to around 12c
Wednesday and Thursday. This pattern will continue above normal
temperatures across northern Michigan through the period...warming
from the mid 60s Monday to the lower 70s by Wednesday.

At the surface...an area of high pressure centered near Hudson Bay
to begin the week will slowly sink south into the north Atlantic by
mid-week...while a system over the Rockies Monday becomes better
organized and lifts into the wrn Great Lakes Thursday. This pattern
will generate some sun and mainly dry conds over nrn Mi through
midweek...while the chance of rain showers increases slightly
Thursday.

SWR

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 138 PM EDT Thu Sep 29 2016

Stubborn, partially lake induced MVFR stcu field starting to
slowly dissipate. This trend should continue, although weak lake
processes will likely keep MVFR cigs in KAPN for several more
hours. Afterwards, moisture rotating in from the south will bring
an additional VFR/MVFR cloud deck overnight, with even perhaps
some light rain reaching KMBL by morning. Additional MVFR cigs and
light rain continues Friday morning. Gust northeast winds expected
through this taf cycle.

&&

.MARINE...
Issued at 312 PM EDT Thu Sep 29 2016

Gusty northeast winds and choppy waves to continue across
much of Lake Michigan and Lake Huron through Friday evening.
Northeast winds will begin to subside some heading through later
Friday night on into the start of the weekend. All inherited
advisories will remain.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...SMALL CRAFT ADVISORY until 5 PM EDT Friday for LHZ347>349.

LM...SMALL CRAFT ADVISORY until 5 PM EDT Friday for LMZ323-342-
     344>346.

LS...NONE.
&&

$$

SHORT TERM...MSB
LONG TERM...SWR/Keysor
AVIATION...MSB
MARINE...MSB