Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 191742

Area Forecast Discussion
National Weather Service Marquette MI
142 PM EDT THU MAY 19 2016

.SHORT TERM...(Today and tonight)
Issued at 254 AM EDT THU MAY 19 2016

Upper air pattern consists of a closed 500 mb low over New England
with a trough in the southern rockies and a trough in the Pacific
NW. There is also a 500 mb ridge over the upper Great Lakes region
this morning and a shortwave near Lake Winnipeg. This shortwave
nearLake Winnipeg moves into the upper Great Lakes region late

Quiet weather will continue for this forecast period and it will
remain dry. Did not make too many changes to the going forecast.

.LONG TERM...(Friday through Wednesday)
Issued at 430 AM EDT THU MAY 19 2016

Dry/pleasant weather is still on track thru the weekend. Current low
amplitude flow across the conus will amplify in the coming days as a
trof amplifies over the far wrn conus thru Sat. This will force a
building ridge over the Plains States into s central Canada this
weekend. As the ridge amplifies, it will force a shortwave se thru
northern Ontario and into the eastern states Sat/Sun. With shortwave
passing well ne of the fcst area, it should not generate any pcpn
here. The plains ridge will then shift over the western Great Lakes
by Mon as a shortwave lifts out of the western trof. Meanwhile, the
shortwave diving se thru Ontario Sat goes on to aid development of a
trof along the East Coast. With this trof then cutting off from the
main flow and evolving into a closed mid level low near the Mid-
Atlantic Coast, the eastward progress of the ejecting shortwave out
of the western trof will be limited and forced on a track passing nw
of Upper MI, potentially well nw of here. This ejecting energy
offers the first mentionable pcpn chance over the next 7 days (Mon
night/Tue), but given the track of the energy nw of here, the
potential for much needed widespread, decent pcpn appears low.
Another shortwave may eject out of the western trof after the first
wave. If so, a better opportunity of pcpn could materialize midweek.
With a pre full-greenup dry spell underway and with limited
evapotranspiration aiding low relative humidity, fire danger will be
on the increase daily. So, while the weather will be quiet into
early next week, fire weather concerns will be growing. Mon will
likely be the day of greatest concern due to strengthening winds.
Looking farther ahead, CPC and NAEFS 8-14day outlooks point toward
above normal temps being slightly favored for Upper MI, though the
NAEFS is showing some trend away from above normal temps.

Beginning Fri, with 850mb temps similar to today, max temps Fri will
be within a few degrees of what is observed today. While there will
be lake breeze development near Lake Superior, it will be weaker
with less inland push than the lake breeze off Lake Michigan due to
a weak s to sw gradient flow. For days, the GFS has insisted on sct
-shra development over much of Upper MI on Fri, and today`s 00z run
is no different. Some of the other available model guidance indicate
the potential of isold -shra, but not even close to the coverage of
what the GFS has and continues to show. There is some shortwave
energy drifting across the area on Fri, weak remnants of the
shortwave trof currently over Manitoba/ND, but it seems it will be
difficult to get sufficient instability to support -shra given the
early season lack of evapotranspiration and also the lack of any
advection of moisture into the area. Fcst soundings show mid level
capping, and with the expected fcst temps, it would require sfc
dwpts approaching the mid 40s to get passed the cap. That`s
unlikely, so maintained a dry fcst with just a greater coverage of
high based cu. For dwpts, favored the bias corrected regional
Canadian model to drive values down into the low/mid 30s in the
interior during the aftn given the recent pattern for dwpts to be
lower than fcst. This will drop min RH down to 20-30pct.
Fortunately, winds will be on the lighter side. Lake breezes will
result in somewhat higher dwpts near the lakes.

Shortwave drops thru northern and eastern Ontario Sat, and
associated cold front will dissipate as it reaches Lake
Superior/Upper MI. With low levels dry and forcing passing well ne
of here, no pcpn is expected. Again, expect high based diurnal cu,
but probably less coverage than Fri. 850mb temps rise 1-2c from Fri,
so high temps Sat will push solidly into the mid/upper 70s over much
of the area inland from the lakes. For dwpts, favored the lower bias
corrected non NCEP guidance, especially the global Canadian model,
to again drop interior min RH down to the 20-30pct range.

As a low pres trof moves out over the western plains and high pres
slips e on Sun, southerly winds will begin to increase a little, and
850mb temps will rise a degree or two from Sat. Away from Lake
Michigan, this should support highs mostly into the upper 70s,
perhaps reaching 80F at some locations over the w. Once again,
favored the lower bias corrected non NCEP guidance for dwpts,
especially the global Canadian model, to drop interior min RH down
to the 20-30pct range.

On Mon, shortwave that ejects from the western trof will lift ne
toward se Manitoba/northern Ontario. Associated sfc trof will
approach the Upper Mississippi Valley, resulting in tightening pres
gradient over the Upper Great Lakes. With 850mb temps rising to
around 13C, Mon will be the warmest day with highs in the upper
70s/lwr 80s away from Lake Michigan. Once again, favored the lower
bias corrected non NCEP guidance, especially the global Canadian
model, to drop min RH down to the 25-35pct range away from Lake
Michigan. With low RH and winds gusting to 20-30mph, perhaps higher
given 30-40kt winds at 850mb, Mon will be the day of most concern
with regard to fire wx, especially over western Upper MI where winds
will be strongest. Could be some -shra late over the far w.

Approaching sfc trof will weaken as it moves into the Upper Great
Lakes Mon night/Tue as supporting shortwave lifts well n to Hudson
Bay and mid/upper ridge remains over the Great Lakes, being held up
by the closed mid level low drifting up the Mid Atlantic Coast. As a
result, pcpn will likely diminish and perhaps fall apart completely
as the weakening trof arrives. This is reflected in an unfortunate
medium range model trend toward less pcpn for Upper MI. In fact, the
Canadian model has no pcpn for much of the fcst area. For now,
nothing higher than low chc pops will be utilized Mon night/Tue.

Sw upper flow continues Wed. With better moisture over the area and
with the potential of additional shortwave energy to lift ne,
lingered low chc pops.

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 141 PM EDT THU MAY 19 2016

With dry high pressure dominating the Upper Great Lakes region,
expect VFR conditions and light winds at all the TAF sites. Expect
some mid-level high based cumulus this afternoon and again on
Friday afternoon.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 254 AM EDT THU MAY 19 2016

A quiet late spring pattern is expected for Lake Superior for the
remainder of this week as high pressure settles over the Great Lakes
region. Winds will be mostly under 15kt each day. Winds on Monday
will increase to 25 knots ahead of a trough lifting through the
Northern Plains.

Upper Michigan...
Lake Superior...
Lake Michigan...


LONG TERM...Rolfson
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