Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 271719

Area Forecast Discussion
National Weather Service Gaylord MI
119 PM EDT FRI MAY 27 2016

Issued at 1133 AM EDT Fri May 27 2016

Upper level ridge axis extends thru the Great Lakes region late
this morning. Surface pattern and thus surface winds are rather
weak and ill-defined attm. Dissipation of dense fog has had to
rely solely on diurnal mixing...which has happened for the most
part. Latest vsbl satellite does show a couple of small areas of
linger fog...but vsbys are quickly improving. Temps have already
popped into the mid 70s to around 80 degrees across much of Nrn
Lwr Michigan...but remain in the 60s across Ern Upr Michigan where
the fog has lingered the longest.

Looking upstream across Wisconsin and Illinois...a few areas of
convection continue to fire and gradually push northward thru
these states. Strengthening low level jet poking into Srn
Wisconsin is providing some added support and moisture transport
to ongoing convection over that region. NAM12...RAP13 and latest
HRRR all redevelop convection over our SW cwa to varying degrees
with slight differences in timing this afternoon. Convection then
spread N/NE thru much of our CWA...especially across Nrn Lwr
Michigan...during late afternoon and early evening. NAM boosts
MUCAPES to around 2000 J/kg this afternoon...while the RAP only
shows around 1500 J/kg for the afternoon. Speed shear actually
diminishes later this afternoon and evening as upper level winds
weaken and low level winds actually strengthen as the eastern edge
of the low level jet leans into Michigan. Going forecast is
handling the situation well...introducing chance pops across our
SW CWA after 18Z and then spreading chances northward thru much
of Nrn Lwr michigan after 21Z. An isold strong/svr storms is once
again not out of the question later this afternoon and evening
during peak diurnal instability combined with some modest shear.


.SHORT TERM...(Today and tonight)
Issued at 339 AM EDT Fri May 27 2016

High impact weather potential: dense fog northern sections this
morning. Isolated svr t-storms again possible in northern lower
this afternoon/evening.

Front has lifted north of eastern upper (noting 60f dew points even
ene of the Sault). Front is progged to settle back into northern
Chippewa Co early this morning (aided by the cold waters of
Superior), then hang out there thru the upcoming day. Our airmass is
largely unchanged from yesterday (if anything we should be a touch
warmer today). However, something of a 500mb shortwave ridge
develops over our heads today, embedded in the broad sw flow aloft.
Will this pose an obstacle to seeing deep convection? Not really.

Today...fog/stratus has become extensive near and north of M-68,
and a dense fog advisory has been posted in response. Far northern
lower mi should start to break up shortly after 8 am, eastern
upper will likely take a couple of hours longer. To the south,
ground fog is present but much thinner, and will burn off quickly
as cloud cover is limited otherwise.

Presently we are in a lull re: low-level southerly flow and
associated warm/moist advection. Currently our 1000-850mb winds
are westerly. That will change during the day, with winds backing
south this morning and increasing this afternoon. 1000-850mb winds
will increase to near 25kt over central Lake MI by late in the
day; that area sits at the nose of the developing low level jet.

Cirrus from upstream convection continues to thin as it tries to
push into northern MI. Don`t anticipate any obstacles (south of
M-68) to strong diurnal heating and another toasty day. Temps
will warm into low/mid 80s in much of northern lower, and into the
70s in eastern upper. Some warming will be seen in the 700-500mb
layer aloft, but this will be insufficient to keep a lid on
things. The Nam is again too juicy down low, and is thus overly
unstable (and consequently a little too fast to develop/expand
convection). Instability will be higher downstate, where dew
points are in the low/mid 60s. This juicier air will creep
northward with time, especially into nw lower MI in the afternoon
where southerly flow is a bit stronger. Mlcapes will reach the
1-1.5k j/kg in nw lower MI this afternoon, and eventually n
central lower and down by Saginaw Bay toward evening. Will keep
the morning/early afternoon dry, then prog sct TSRA after 2 pm,
starting in nw lower and expanding n and e with time. Will not
bring pops quite as far north as the Sault, nor quite as far east
as APN.

The increase in low-level winds will actually reduce 0-6km shear
as the afternoon proceeds, from near 40kt at 18z to 20-25kt at
00z. Instability and shear levels both seem to be at, or very
slightly less than, yesterdays values. That would suggest that an
isolated svr threat is once again present. CIPS analogs are much
more impressed with downstate locales, but definitely extend a
risk north into northern lower. This risk will carry into the
evening hours, before heating is lost.

Tonight...low level flow increases as pressure gradient tightens
between high pressure off the east coast and low pressure in the
central plains. This will support multiple clusters of shra/tsra
lifting nne across the mid/upper MS valley and western lakes. We
will be on the eastern portion of the developing warm conveyor
belt and associated convection, and thus pops will decrease
somewhat from w to e. However, still anticipate likely pops or
better just about everywhere, with the OSC/Tawas area the possible
exception. Precip will be moving fairly quickly northward, which
will limit heavy precip potential. And any risk for strong/svr
storms diminishes by overnight as the BL stabilizes.

Min temps upper 50s to mid 60s.

.LONG TERM...(Saturday through Thursday)
Issued at 339 AM EDT Fri May 27 2016

(5/28)Saturday...Models still seem to be handling the details of the
upcoming days poorly. A sfc low in the Midwest will move to the
north into the Upper Mississippi Valley. This looks to move a warm
front north of the forecast area, by 00z. Coupled with the somewhat
diffluent flow at 500 mb over Michigan, will expect that showers and
thunderstorms will break out, mainly after 15z as the warm front
moves north and the sun is able to destabilize the atmosphere. after
00z, it looks like much drier air will move into the region and with
the diurnal heating gone, the showers should diminish. Shear
parameters look to be less than today, so think that the severe
threat should be a little less than the last day or two.

(5/29)Sunday...Models have a decent 500 mb trough bearing down on
the Upper Great Lakes with the decent cold front associated with it.
with the heat and humidity at the sfc and the 500 mb 40-50 knot jet
streak moving into the region, will need to watch the thunderstorms.
If this came through a little later in the afternoon, it would be
more impressive with the added instability. However, the main rain
looks to be done by 21z with some showers following, then cooling
and drying overnight as the 500 mb flow turns more zonal.

Extended (Monday through Thursday)...Monday starts off with zonal
flow across the northern part of the CONUS, which should keep us
dry. Tuesday, however, looks to bring some 500 mb ridging into the
Upper Great Lakes. The only question will be how amplified the ridge
will be. The ECMWF solutions is pretty amplified, with a much deeper
cut off low (500 mb) dropping into the N Plains. The latest GFS is
beginning to trend toward the ECMWF idea, as the 00z run shows a
stronger low than the 18z run did. Which, if this is the case, then
the ridging ahead of the low should become more amplified like the
ECMWF. This would slow down the rain expected Tuesday that the GFS
purports, and speed up the cold frontal passage on Wednesday that
the ECMWF shows. Although, when looking at Thursday the ECMWF is
post frontal and dry, while the GFS is pre-frontal with rain moving
into the region by the afternoon.


.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 119 PM EDT Fri May 27 2016

Scattered showers and thunderstorms will redevelop this
afternoon...initially around MBL and TVC and will then spread N/NE
to PLN and APN later this afternoon and early evening. Areal
coverage of this precip will increase thru the night and into
Saturday as an area of low pressure and associated deep moisture
lift northward into the Wrn Great Lakes region. Winds will remain
generally from the SE under 10 kts tonight...shifting to the south
on Saturday.


Issued at 339 AM EDT Fri May 27 2016

Winds and waves will remain below SCA criteria thru Saturday.
However, southerly winds will increase somewhat tonight,
especially on Lake MI. Things will become a bit on the choppy side
late tonight into early Saturday as a result. Otherwise, marine
fog and stratus will continue to be major issues at times,
especially north of Alpena and Gd Trav Lt. Periodic showers and
t-storms will also be seen, with another round expected this
afternoon thru tonight.


.APX Watches/Warnings/Advisories...


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