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Area forecast discussion 
National Weather Service Gaylord Michigan
126 PM EDT Sat Jul 4 2015

Update...
issued at 119 PM EDT Sat Jul 4 2015

Diurnal cumulus fields beginning to grow and still expecting a few
showers/thunderstorms to develop over southeast parts of the area this
afternoon. Otherwise...current forecast on track with few changes
anticipated.

Update issued at 1019 am EDT Sat Jul 4 2015

Marine fog/stratus beginning to mix out over parts of eastern
upper this morning. This trend should continue over the next 1-2
hours with a good deal of sunshine expected over all of eastern
upper by early afternoon. Elsewhere...mostly sunny skies across
northern lower /albeit a bit smoky/. Expecting some diurnal cumulus
development this afternoon...especially southern/eastern areas.
High resolution short range models continue to show pop-up
showers/thunderstorms east of I-75 and south of Alpena this afternoon.
Very skinny MLCAPES of 750-1000 j/kg over this area with no
shear...so no severe weather expected. Will leave low probability of precipitation in
that part of the area for this afternoon and early evening.
Overall...a very nice July 4th weatherwise across northern
Michigan with near normal highs in the 70s to lower 80s.

Update issued at 736 am EDT Sat Jul 4 2015

Updates made to account for marine fog/stratus deck that is making
steady inroads into eastern Upper Michigan. Locally dense fog was added
to the hazard weather outlook. Stratus likely has another 1-2 hours of
expansion before the sun GOES to work on it...after which it will
quickly erode (except perhaps along the immediate Superior
shoreline).

&&

Near term...(today through tonight)
issued at 330 am EDT Sat Jul 4 2015

High impact weather potential...scattered T-storms middle-afternoon
to middle-evening southeast sections.

High pressure has been displaced slightly southward to Southern
Lower Michigan. 1005mb low pressure is moving east from the southern tip
of James Bay. Several troughs emanate from this low...one moving
across eastern Upper Michigan and just east of grb. The primary thermal-
moisture boundary extends roughly along the South Shore of Superior.
The last of the diurnal rain showers ended between midnight and 2
am...though a healthy amount of middle clouds remain over northern
lower Michigan. Potential for diurnal convection is again the main
concern.

Today...cold front will gradually slip south across northern lower
Michigan. Good agreement among NAM/rap13 runs that a wave will develop
along the front by middle-afternoon over the southeast quarter of the forecast
area. This wave forms thanks to a ripple in the northwest flow
aloft...combined with Land-Lake thermal responses to heating. But
will localized convergence in the southeast result in convection? The NAM
and NSSL WRF aggressively argue yes...the rap no. The NAM is
overdone when it comes to it/S surface parcel (as is common)...78/59
is more reasonable than 82/62. But even after making that
adjustment...21z MLCAPE should reach near 1100j/kg. Warmer temperatures
above 640mb results in a fairly skinny cape (li -1/-2)...but not
warm enough to impose a cap. Given lake breezes will serve as a
trigger...am reasonably confident that some spotty convection will
occur in southeast sections. Will go with a scattered pop after 19z/3 PM...S of
apn and near/east of htl. Wind fields up to 700mb are less than
15kt...so shear and severe potential is not impressive.

Elsewhere...a partly to mostly sunny 4th is expected. Highs will
range through the 70s to near 80f.

Tonight...shra/tsra chances will linger into middle-evening in the far
southeast...parts of Iosco/Arenac/Standish counties. However...northwest surface
winds/cool advection will be established very shortly after 00z.
Will keep things dry after 02z/10pm. Spotty surface based convection
should fire late this afternoon in northern WI...but this activity
will not be able to cross chilly Lake Michigan this evening. Could see
some residual cloud cover reach northwest lower Michigan...but otherwise skies
will clear tonight. Min temperatures will range through the 50s.

&&

Short term...(sunday through Monday night)
issued at 330 am EDT Sat Jul 4 2015

High impact weather: none

Forecast challenge: frontal passage Monday.

(7/5)sunday...the system in the plains begins to deepen, allowing
the cold front to stall. There were warning signs the last few days
that this would happen. The high moves east of the upper Great Lakes
and allows the moisture and warmth to build S the return flow get
going. Looks like a good portion, or maybe even most of north Michigan
will get into the lower 80s. Overnight, the front approaches the
upper Great Lakes, but the surface low begins to move up the front. So
that the front lies on a line from the southern tip of James Bay
down to kmsp. This holds the system up by about 6-12 hours into
Monday.

(7/6)monday...again, the models have had to hold the system up as
the surface low continues to deepen and head up across Lake Superior.
Once it does, then the cold front begins to rush into the forecast
area, around 00z. Of course, as the surface low and the 500 mb shortwave
continue NE, the front does have the momentum, but looks like it
loses its dynamic lift. The front looks to be through the forecast
area overnight, to early Tuesday morning.

&&

Long term...(tuesday through friday)
issued at 330 am EDT Sat Jul 4 2015

Extended (tuesday through friday)...think that the gfs's faster
progression with the system by 18z looks better as the wave lifts
out of the upper Great Lakes and into Quebec. High pressure builds
into the region and looks to keep the region dry through at least
Thursday morning. Thursday and Friday, the models are at odds with
the GFS bringing rain through the region, while the European model (ecmwf) is dry. So
far the consensus is for slight chance pops, so really, it beginning
to look dry through the end of the week.

&&

Aviation...(for the 18z tafs through 18z Sunday afternoon)
issued at 119 PM EDT Sat Jul 4 2015

A few rain showers/thunderstorms and rain possible this afternoon over NE lower Michigan...south
of apn. So no trouble anticipated at taf sites. Hazy conditions
/mainly due to smoke from Canadian fires/...with diurnal cumulus
developing over inland areas. Areas of fog after midnight
tonight...with IFR visibilities possible at pln/mbl. After early morning
fog dissipates...VFR conditions expected on Sunday with light
winds.

&&

Marine...
issued at 330 am EDT Sat Jul 4 2015

High pressure centered over Southern Lower Michigan will maintain weak
winds and waves through tonight. Small craft advisories are not
anticipated. Scattered PM T-storms are expected today in NE lower
Michigan...south of Alpena. Some of these could bring brief gusty winds
to the nearshore waters.



&&

Apx watches/warnings/advisories...
Michigan...none.
LH...none.
Lm...none.
Ls...none.
&&

$$

Update...keysor
near term...jaz
short term...jsl
long term...jsl
aviation...keysor
marine...jaz

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