Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 271426
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
1026 AM EDT Thu Apr 27 2017

.UPDATE...
Issued at 1025 AM EDT Thu Apr 27 2017

Surface low over S Lk MI this morning with front extending north
through the central UP. Showers staying generally west of the
front and low over WI and W UP. Another surface trough extends
from N Lk MI down to the Ohio/IN border where some scattered
showers are breaking out. Entire system moves north today so bulk
of wet weather will miss our area. However, forecast soundings
show some instability east of the surface trough. CAPE values of
100-200 J/kg are forecast. Looks like any preciptitation we get
today will develop along this boundary east of I-75. Otherwise,
just some scattered areas of light rain or showers near Lk MI
closer to the low as it passes by. Strong winds will continue this
afternoon with 50-60kts of low level flow just off the surface.
Winds relax overnight as the low moves away.

&&

.NEAR TERM...(Today through Tonight)
Issued at 313 AM EDT Thu Apr 27 2017

High Impact Weather Potential...Showers and a few thunderstorms thru
early afternoon...with precip chances diminishing thereafter.

Pattern Synopsis/Forecast...Elongated area of low pressure extends
thru Lake Michigan southward thru Illinois to near STL early this
morning. Large area of showers and thunderstorms continue to push
northward along this feature...with the leading edge of this wave of
precip now reaching western sections of our CWA. Majority of low
stratus/fog off of Lake Huron has dissipated per regional obs. Temps
remain quite mild in most locations...holding mainly in the 50s and
even lower 60s in some spots as WAA persists just ahead of the
surface low center.

Latest short term models show 3 waves of precip set to impact our
CWA today into this evening. Area of showers currently moving thru
mainly our western CWA is the first wave. Precip has shown a gradual
diminish in both areal coverage and intensity as it pushes north
thru Lake Michigan into our area...which is no surprise given
diminishing instability as it moves into Northern Michigan. MUCAPES
are struggling to reach 250 J/kg across our CWA during diurnal
instability minimum. As we move into the day...instability will
increase ahead of the low as daytime heating lends a hand. Greatest
instability will be focused across NE Lower Michigan where WAA and
moisture advection will be greatest. Some wind shear will exist...
which may lend to the development of a few organized storms. Thunder
threat will quickly end toward mid/late afternoon with passage of
the low and associated cold front. Thus...high temps will actually
occur by around midday/early afternoon...ranging from the upper 50s
in Eastern Upper Michigan to the upper 60s in NE Lower Michigan.
Temps will slowly diminish during the rest of the afternoon and
early evening as CAA begins.

An area of wrap-around moisture will swing thru mainly northern
sections of our CWA this evening as the surface low center continues
N/NE thru Eastern Ontario to near James Bay by 06Z Friday. A few
showers will linger during the evening for Eastern Upper Michigan
and the Tip of the Mitt. Otherwise...skies will remain mostly cloudy
thru much of the night...with some decrease in clouds from south to
north very late. Temps will be noticeably cooler tonight with
ongoing CAA. Low temps will fall mainly into the 30s.

&&

.SHORT TERM...(Friday through Saturday)
Issued at 313 AM EDT Thu Apr 27 2017

...Cooler; showers returning late Friday...

High impact weather potential...None.

Pattern Synopsis/Forecast...A dry airmass with PWATs around 0.3"
(which is at the lower quartile for late-April at KAPX) will
initially be in place across northern Michigan Friday morning.
Moisture will steadily rise through the day ahead of a weak cold
front that will drop south across the area Friday evening. The front
itself will struggle to generate precip, but shortwave energy
lifting out of the Plains into the Upper Great Lakes will bring a
chance of showers to parts of northern Lower late afternoon into
Friday night. Surface high pressure and rising heights aloft will
allow for dry conditions on Saturday. A cooling trend will be
ongoing for the end of the week with highs Friday in the 40s to low
60s and Saturday in the 40s to mid 50s. With Friday night lows in
the 30s, cannot rule out perhaps a few wet snowflakes mixing in here
and there within the higher interior terrain.

Primary Forecast Concerns...Medium confidence in rain chances late
Friday into Friday night. Recent model runs are still showing some
variance with regard to placement and timing of the showers, but in
general the rain will remain over the Lower Peninsula, with
increasing chances south of M-32 heading towards Saginaw Bay. Other
than perhaps a stray shower along the cold front Friday
afternoon/evening, eastern Upper should remain mostly dry.

.LONG TERM...(Saturday night through Wednesday)
Issued at 313 AM EDT Thu Apr 27 2017

High impact weather potential...Several rounds of widespread
rainfall are likely late Saturday night through Monday. Moderate to
heavy rain and some thunderstorms will be possible Sunday night.

A highly amplified upper level trough just east of the Rockies
Saturday night will lead to the development of a strong system over
the Southern Plains. This potent system will interact with a rich
supply of Gulf moisture as it occludes and lifts into the Upper
Midwest Sunday into Monday. Across northern Michigan, PWATs will
rise above 1" on Sunday, climbing to 1.5" near Saginaw Bay by Monday
morning. As broad WAA, frontogenetic forcing, DPVA, and a vigorous
LLJ all come into play with this moisture rich environment, several
rounds of widespread precipitation will overspread northern Michigan
from late Saturday night through Monday. Of course most of this will
be rain, but Saturday night`s lows in the 30s may again allow for
some wet snowflakes to mix in over the higher interior terrain of
northern Lower. Forecast soundings show strong, deep omega from
Sunday through Monday, particularly Monday morning as the core of
the system moves through. Elevated convection will also allow for
some thunder potential Sunday night into Monday morning, mainly
south of M-72.

Monday night through Tuesday will bring some wrap-around showers
from this system as it gradually departs. A drier airmass will then
settle in towards the middle of next week with temperatures holding
near or just below seasonal normals.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 645 AM EDT Thu Apr 27 2017

Waves of showers and MVFR/IFR conditions will impact Northern
Lower Michigan thru Friday morning as low pressure tracks just
west of our area. Thunderstorms are also possible...but chances
are too small to include in the TAFs for now. S/SE winds will
become SW this afternoon with gusts of 15 to 25 kts expected.


&&

.MARINE...
Issued at 313 AM EDT Thu Apr 27 2017

SCA conditions will continue for all of our nearshore areas today
and this evening as S/SE winds continue to gust to 15 to 25 kts...
and then shift to the W/SW this afternoon and evening as low
pressure slides just to our west. Waves of showers and thunderstorms
will impact much of our area thru early afternoon...diminishing to
scattered showers for the rest of the day and into the evening hours
as CAA kicks in the wake of the departing low.


&&

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

$$

UPDATE...KJF
NEAR TERM...MLR
SHORT TERM...MEK
LONG TERM...MEK
AVIATION...MLR
MARINE...MLR


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