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fxus63 kmqt 191139 
afdmqt

Area forecast discussion
National Weather Service Marquette Michigan
739 am EDT Fri Jul 19 2019

Short term...(today and tonight)
issued at 416 am EDT Friday Jul 19 2019

..hot and humid today with chances for severe thunderstorms tonight...

Rather uncomfortable pre-dawn temperatures were observed across the
Upper Peninsula this morning, with temperatures in the upper 60s to
mid to upper 70s. A few areas of fog did develop this morning, but
overall the majority of the more impactful fog remained over Lake
Superior. Outside of a narrow branch of storms moving east-northeast
just across the border in Wisconsin, a complex of thunderstorms dove
southeast across southern Wisconsin early this morning. With pre-
dawn temperatures already 5 to 10 degrees away from our typical day-
time highs for this time of year, today certainly is going to be a
hot day across the area. The main weather concerns for today/tonight
are the heat and humidity expected to build throughout the day and
then chances for a complex of severe storms rolling across the Upper
Peninsula this evening and overnight.

First, the expected heat and humidity. Today will be a hot day
across the area with temperatures pushing well into the upper 80s
and lower 90s, with mid to perhaps even upper 90s in a few spots. As
for the humidity levels, high-res and medium range guidance are
picking up on drier air aloft mixing down, mainly across the west
and north central later this afternoon. Based on 00z soundings
upstream of the area and low- to mid-level water vapor imagery
showing significant mid-level drying (around 850-600mb per CIMSS
GOES weighting functions) moving into the area, this diurnal mixing
and dry does seem feasible across the west. This drying will mix out
some of the humidity, but it also may allow temperatures to warm
even more then currently forecast. The truly, uncomfortable and
oppressive humidity is expected to persist along and north of Lake
Michigan. Did opt to issue an Special Weather Statement for the hot and humid conditions
expected today as we will bump up against heat advisory criteria at
times later today.

Next comes the potential for severe storms later this evening and
into the overnight hours. Low pressure developing in the Lee of The
Rockies will shift eastward into the upper Mississippi/Great Lakes
region this evening and overnight. Its associated warm front will
push into far southern and south central Upper Michigan tonight,
bifurcating the oppressive humidity to the south and slightly less
humid air to the north. This front looks like it will serve as the
mechanism for convection to anchor to later today/tonight. With the
best moisture expected along the Wisconsin border and across the
south central into eastern parts of Upper Michigan, thinking that is
going to be the prime area for severe weather chances. There is
still quite a bit of uncertainty in how far north convection will
get. Along and south of the warm front, it does look like a volatile
environment will setup this evening into the overnight hours as cape
values approaching and/or exceed 2500+ j/kg and deep-layer shear of
45 to 55 knots develops. With shear oriented quasi-parallel to the
warm front, initially any isolated convection will have the
capability of all severe weather hazards. As cold pools merge
convection is expected to grow upscale into an MCS, all hazards will
still be possible, but with a higher emphasis on damaging winds.

Long term...(saturday through thursday)
issued at 448 am EDT Friday Jul 19 2019

Models suggest that the quasi-zonal pattern will amplify from this
weekend into next week as a ridge builds from the SW Continental U.S. Into
Alberta/Saskatchewan with a downstream trough from Quebec into the
eastern Continental U.S.. the resulting NW flow through the northern Great
Lakes will bring seasonably cooler and drier air into Upper
Michigan.

Saturday and Saturday night, the expected mesoscale convective system moving through or near
Upper Michigan Friday night will help push the frontal boundary
farther south from Upper Michigan. Even with another shortwave
likely moving toward the area, the cams, which keep additional
convection mainly through WI and possibly southern Upper Michigan,
seem more reasonable. However, the potential remains for some
shra and a few tsra even into the north. Max temps will depend on
the amount of convective debris and clearing into the afternoon,
but should still reach the upper 70s to around 80. Drier air will
also begin to spread through Upper Michigan with dewpoints
dropping into the 50s. Any remaining shra/tsra over the south
during the evening will diminish or exit to the south and east
overnight.

Sun-Mon, dry weather will prevail as sfc high pressure builds
eastward from the northern plains. Comfortable July weather is
expected with highs in the mid 70s and lows in the upper 40s to
lower 50s. Dewpoints will also drop into the upper 40s.

Tue-Thu, expect increasing temps as the high settles toward the Ohio
Valley with westerly low level flow also bringing warmer air and
slightly more moisture. Any weak shortwaves in the NW mid/upper
level flow could trigger some isold/sct shra/tsra by Wed/Thu. With
limited coverage or upper level forcing, mainly dry conditions will
still prevail through the week.
&&

Aviation...(for the 12z tafs through 12z Saturday morning)
issued at 739 am EDT Friday Jul 19 2019

Shallow ground fog has impacted kiwd/ksaw this morning, but this is
not expected to persist now that the sun has come up. Ksaw has
observed IFR ceilings, expect this to continue until the low-level
moisture mixes out later this morning. Today will be a hot day
across all terminals, chance for thunderstorms this evening.
Confidence wasn't high enough to go with prevailing tsra, but will
let the day shift take a closer look and see how upstream convection
may impact our chances later this evening/tonight. However, did try
to time out the best chances for each terminal with mentions of thunderstorms in the vicinity
later this evening/tonight at ksaw/kiwd.
&&

Marine...(for the 4 am Lake Superior forecast issuance)
issued at 416 am EDT Friday Jul 19 2019

Fog is expected to persist through at least today across much of the
lake, especially the north central and east. Winds will approach 20
knots today, and then will remain below 20 knots through the rest of
the forecast. Thunderstorms are possible this evening across the far
western parts of the Lake, A few could be strong to severe with hail
and gusty winds.
&&

MQT watches/warnings/advisories...
Upper Michigan...
none.
Lake Superior...
dense fog advisory until 8 PM EDT this evening for lsz263-264-
266-267.

Lake Michigan...
none.
&&

$$

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