Area Forecast Discussion
Issued by NWS Marquette, MI

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
FXUS63 KMQT 240820

Area Forecast Discussion
National Weather Service Marquette MI
420 AM EDT Mon Jul 24 2017

.SHORT TERM...(Today and tonight)
Issued at 413 AM EDT MON JUL 24 2017

No significant weather both on land or water through tonight. High
pressure of 1018mb centered near Duluth MN slides across Upper
Michigan and Wisconsin through this aftn and becomes centered over
eastern U.P. and northern Lower Michigan tonight. Dry airmass and
mixing with the high should dissipate stratus and fog over far
west U.P. shortly after sunrise. No real clouds are then expected
the rest of the day. Northerly winds off Lake Superior will
persist over the eastern forecast area but west will see lighter
winds and developing lake breezes late morning/early aftn. After
the chilly conditions on Sunday (except scntrl vcnty of IMT to
MNM), it will be *much* warmer today. High temperatures will
climb into the upper 70s inland west and into the low to mid 70s
inland central and east and also near Lk Michigan. Coolest
readings in the upper 60s will be where the onshore winds persist
all day near Lk Superior.

High pressure/light winds over the east tonight and skies will
remain clear. With that setup went for lows in the 40s inland
central and east. Temperatures will be in the 50s elsewhere,
warmest over far west with developing return flow there. Could be
some patchy fog overnight inland east.

.LONG TERM...(Tuesday through Sunday)
Issued at 344 AM EDT MON JUL 24 2017

The main concern through the extended will be the arrival of a cold
front late Tuesday through Wednesday, with the possibility of a few
strong to severe storms. Otherwise, the latter half of the week and
the first half of the weekend should remain dry as high pressure
takes over behind the exiting cold front. Towards the end of the
weekend, another trailing cold front is progged to move across Upper

Ahead of the cold front there is some uncertainty in how warm 850mb
temperatures will get, for the most part models are ranging between
15 and 20C. This warm air advection coupled with increasing gradient
flow from the south-southwest will allow downsloping to aid in the
warming. Therefore, have continued the trend of bumping temperatures
up a bit, especially across the west and central portions of Upper
Michigan. Winds should increase throughout the day as the pressure
gradient builds ahead of the approaching cold front, so confidence
in any lake breezes developing along Lake Superior are rather low at
this time. Therefore, currently thinking that any storms that do
develop Tuesday afternoon/evening should be confined mostly to the
western portions of the area once the 900-800mb moisture transport
starts to ramp up. A few storms in the evening may be strong to
severe, but it looks like the better instability will not arrive
until the overnight hours as the deeper moisture lifts across the
area. Therefore, Tuesday night with the medium range models
suggesting upwards of 1000-200 J/kg of MUCAPE with moisture
transport streaming across the area wouldn`t be surprised if a few
storms remain strong to marginally severe. As we progress into the
early morning hours on Wednesday, the 1-7km shear really starts to
drop off, from around 30-40 knots to maybe 15-20 knots; therefore,
while showers and storms will continue to push east across Upper
Michigan, the intensity of the convection should begin to wane. On
Wednesday, things get a bit more complicated as ongoing showers and
storms and their resulting cloud cover may inhibit the amount of
diurnal instability that develops during the afternoon hours. It
isn`t out of the question that convection strengthens in the
afternoon as it tries to become more surface based, but it seems
more plausible that storms may just pulse up and down. If storms can
become surface based in the afternoon, with 0-6km shear increasing
to around 40-50 knots, we would be looking at a high shear, low CAPE
day where some rotating updrafts may be able to sustain themselves.

The front is expected to push southeast of the area Wednesday night
into Thursday as a post-frontal dry and stable air mass drops south
from Canada and high pressure begins to take over through the first
half of the weekend. Cold air advection doesn`t look terribly strong
behind the exiting cold front, so afternoon insolation should be
more than enough to modify temperatures nicely during the afternoon
hours each day. The latter half of the weekend a weak cold front
will push south across the area. Confidence at this time is not high
as to whether or not we will see any precipitation out of the front.

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1222 AM EDT MON JUL 24 2017

Low level moisture and light winds has resulted in dense fog and
VLIFR conditions already setting up at IWD. Expect little
improvement through the night but should see quick improvement
after sunrise this morning. Skies have cleared out at CMX and SAW
this evening. Could be some fog at both sites as radiational
cooling will be substantial enough to allow fog to form as high
pressure builds over the area. LIFR vsby of a 1/2sm to 1sm are
possible at both sites. Any low clouds and fog at CMX and SAW
should diminish quickly after sunrise this morning. &&

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 413 AM EDT MON JUL 24 2017

Winds will be 15 knots or less through Tuesday morning with high
pressure overhead. The next chance for stronger winds from the south
to southwest over 20 kts will be Tuesday afternoon into Wednesday
morning over eastern sections as a low pressure trough crosses the
region. Otherwise, winds this week will be 15 kts or less.

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


LONG TERM...Ritzman
MARINE...JLA is the U.S. government's official web portal to all federal, state and local government web resources and services.