Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 311749
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
149 PM EDT TUE MAY 31 2016

.SHORT TERM...(Today and tonight)
Issued at 427 AM EDT TUE MAY 31 2016

00Z raobs/latest wv imagery and RAP analysis show a shrtwv rdg axis
over the wrn Great Lks to the E of a fairly vigorous shrtwv moving E
thru the nrn Plains. Despite the presence of this rdg axis and dry
air shown on the 00z INL/GRB raobs, there have been some isold
showers over the far wrn CWA in Gogebic and Ontonagon Counties
associated with axis of some h85 fgen/h85-7 theta-e advctn in that
area well ahead of the shrtwv to the W. Except for some patchy hi
clds over nrn Lk Sup, skies farther to the E are generally moclr
deeper into the dry airmass associated with sfc rdg axis extending
fm hi pres center over Hudson Bay into the Upr MI. Looking farther
to the W, there is a much more wdsprd area of showers/TS over the W
half of MN under warm conveyor belt mstr ribbon ahead of the nrn
Plains shrtwv.

Today...Some of the hier res models show the isold showers over the
far W early this mrng moving as far NE as the Keweenaw and even near
Marquette by 12z as axis of h85-7 fgen shifts slowly in that
direction. But since the h85-7 mstr advctn is progged to fade slowly
as the band moves toward the core of the drier air, expect any isold
showers early this mrng to be confined to just the far W. The
showers over the far W are likely to begin to increase in coverage
later this mrng as axis of deeper mstr associated with warm conveyor
belt to the W pushes into that area. But the guidance is fairly
consistent on showing a fairly sharp ern edge to the pcpn shield fm
about the Keweenaw to Iron County that wl be maintained by more
persistent llvl dry air related to sfc-h925 ESE winds on wrn flank
of only slowly retreating sfc rdg axis held in place by rising upr
hgts to the E of slowly moving shrtwv in the nrn plains. Expect
incrsg mid/hi clds in this area with the arrival of some hier lvl
mstr. These clds wl hold down max temps. The far E wl be warmest
with max temps at least close to 70 as that area wl see more
sunshine.

Tonight...As the shrtwv moves slowly to the E and hgts fall slowly
over the CWA, the warm conveyor belt mstr ribbon is fcst to edge
slowly to the E as well. Incrsg upr dvgc/h85-7 mstr transport/deep
lyr qvector cnvgc with pwats incrsg up to about 1.5 inches /about
200 pct of normal/ wl support arrival of likely/categorical pops
over the W half. But there wl be a sharp ern edge to these hier pops
with lingering llvl dry air and weaker forcing over the ern CWA
closer to slowly departing rdg axis. Despite the deep moistening/
sharp dynamics, model fcst SSIs/unimpressive lapse rates support no
more than a shc of TS even under the deeper mstr/axis of hier pops.
With the clds/increasing mstr and steady S winds, tngt wl be much
warmer than early this mrng with lo temps probably not falling much
blo 60 in the downslope areas near Lk Sup over the W half of the
CWA.

.LONG TERM...(Wednesday through Monday)
Issued at 427 AM EDT TUE MAY 31 2016

Trending cooler with several chances for rain over the next week.

Wednesday: A mid-level low over the northern Plains early this
morning will drift eastward through the remainder of the week,
passing just north of Lake Superior on Thursday. A narrow band of
showers forced by an embedded trough axis swinging around the low
will be ongoing across western Upper MI Wednesday morning. Expect
coverage to increase as the band spreads eastward across central
Upper MI by the afternoon as the right entrance of a developing
upper jet streak interacts with the trough axis and increasing low-
level moisture. The band should then clear the far east around
midnight Wednesday into Thursday. Marginal mid-level lapse rates
will lead to negligible instability, so chances of thunder will be
extremely small with this band of showers.

After the showers clear, mid-level drying across the west and
central will produce clearing skies that will allow the low-levels
to recover by Wednesday afternoon. The main axis of the
aforementioned trough may generate a few showers, but the amount of
instability generated will again be negligible under marginal mid-
level lapse rates.

Also of note Wednesday will be a LLJ of up to 45kts as low as 2kft
AGL across the east. Strong low-level stability under a stout
inversion will likely prevent most of this wind from being realized
at the SFC.

Thursday: Cooler conditions are expected Thursday under the passing
mid-level trough/low. A diurnally enhanced deck of strato-cumulus
will develop, but shallow cloud depths under a low inversion should
limit precip to just some sprinkles inland during the afternoon.

Friday through Monday: Guidance continues to trend toward a cool and
unsettled weekend as a transition to deep troughing begins across
eastern North America. After a chilly Thursday night, mid-level
ridging will bring dry conditions for Friday. A clipper system will
then dive SE into the Upper MS Valley Friday night, bringing with it
a chance for showers, especially for the west half. The low will
drift eastward across the region through Sunday, resulting in
continued chances of showers through the weekend. There may be a
period of some clearing on Saturday just ahead of the main low to
generate enough instability for some thunderstorms, but left them
out of the forecast for now. By Monday, the low should move far
enough east to limit showers to just the east half.
&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 149 PM EDT TUE MAY 31 2016

Lingering low-level dry air will ensure vfr conditions continue this
aftn at KCMX/KSAW. Vfr conditions should continue at KIWD as well,
but if passing shra affect the terminal, there may be some brief
mvfr conditions. As a more consolidated ribbon of shra slowly
spreads e across the area tonight/Wed morning ahead of a cold front,
expect conditions to deteriorate to at least mvfr at all terminals,
with some ifr as well. With an upslope southerly wind Wed morning,
KSAW is most likely to see ifr conditions. Behind the ribbon of
shra, KIWD/KCMX should break out to vfr Wed morning/early aftn. LLWS
will be possible tonight at KCMX/KSAW.
&&

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 427 AM EDT TUE MAY 31 2016

Expect NE winds today between hi pres over Hudson Bay and
approaching lo pres in the northern plains to peak as hi as 30 kts
over the western lake, where the gradient will be sharpest and
terrain funneling will accentuate the NE winds. Not out of the
question there could be a few gale force gusts to 35 kts in that
area. Expect the winds to veer toward the S later tonight into Wed,
when the lo pres will move into Ontario. Stronger SE to S winds up
to 30 kts tonight into Wed morning over mainly the E half will
diminish thru the day as a weaker gradient develops overhead.
Although the air over Lake Superior is dry now, expect fog to
develop W to E late today thru Wed as rain showers overspread the
area and the increasing SE to S flow advects more moisture into the
Upper Lakes. After the cold front associated with the low moving
thru Ontario passes Wed night into Thu, W winds up to 20-25 kts will
drag drier air over the Lake and dissipate the fog. Hi pres building
over the western Lakes late Thu into Fri will then bring a period of
light winds/quiet weather. More showers may arrive with the next lo
pres on Sat, but right now winds look to be no hier than about 20
kts.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&

$$

SHORT TERM...KC
LONG TERM...Kluber
AVIATION...Rolfson
MARINE...KC


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