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National Weather Service Gaylord Michigan
1148 PM EDT Thursday Aug 28 2014

issued at 354 PM EDT Thursday Aug 28 2014

High pressure over northern Michigan will continue to provide
seasonable conditions this afternoon before slowly moving toward the
East Coast tonight. Low pressure from the Central Plains will move
into to the Great Lakes region Friday through Saturday
night...bringing periods of rain and embedded thunderstorms with
potentially heavy rainfall.

Conditions quiet down for Sunday...before another front and
unsettled weather arrives Monday. High pressure and quieter weather
is then expected to build into the Great Lakes.


issued at 938 PM EDT Thursday Aug 28 2014

High clouds continue to expand into northern Michigan...with some middle
clouds and virga making inroads into northwest lower Michigan. -Ra has moved
into NE WI...including mtw. Radar trends are in agreement with the
going forecast for -ra reaching mbl toward or just after
06z/2am...and slowly expanding east and north. However...upstream radar
trends (and short-term model guidance) are slowing things down
along the north fringe of the precipitation shield. Have thus slowed down
precipitation onset in eastern upper and tip of the mitt counties...with
only a chance of -ra in western Mackinac by 12z/8am. No big
changes to readings will stabilize during the overnight


Short term...(this evening through tonight)
issued at 354 PM EDT Thursday Aug 28 2014

..not as cool tonight with rain possible late...

High impact weather potential: none tonight.

High pressure over the region this afternoon will shift off to our
east later tonight allowing a storm system in the plains to approach
from the west. Any daytime instability driven cumulus clouds will
dissipate late this afternoon allowing for decent radiational
cooling conditions early tonight (despite increasing high level
cloudiness) out ahead of incoming system. However...tightening south
southeasterly gradient and increasing and thickening clouds
overnight should put a lid on falling temperatures. Did drop
forecast lows by a couple of degrees which now range from the upper
40s to middle 50s. Meanwhile...moisture will slowly increase
overnight (precipitable waters approaching 1.5 inches by 12z fri)
allowing for showers to approach from the southwest and eventually
moisten the column enough to reach the ground by around daybreak
across far western zones...and bring a chance for showers across
central zones while eastern zones likely remain dry.

Long term...(friday through thursday)
issued at 354 PM EDT Thursday Aug 28 2014

..heavy rainfall possibilities to start the Holiday weekend...

Tight/low amplitude flow pattern in place around the northern hemisphere
today with a progressive flow across the higher latitudes. Broad
ridging persists across the central/Southern Plains where a very
warm/moist airmass has set-up from the central/Southern Plains to the
Gulf Coast states. Meanwhile...high pressure is sitting across the
Great Lakes today bringing US decent weather for now. Upstream...
slow moving pseudo-cutoff low pressure system now moving through the
Central Plains today with a stalled front draped from the Central
Plains through the Ohio Valley.

Forecast overview...Central Plains system will get slowly drawn
northeastward up across the Great Lakes aided by a northern stream low
pressure system/cold front and upper jet core moving into and across
eastern Canada. Strong low level jet accompanying this feature will
pull very moisture rich air (theta-east plume with precipitable water values in
excess of 1.5 inches) up through the Great Lakes along and ahead of
the cold front that will then slowly advance across northern Michigan
through Saturday night...while slow moving short wave takes it/S
time lifting up through the region along the front. The end result
will be several rounds of rainfall out of this system and an axis of
heavier rainfall aligned parallel with the incoming slow moving
front impacting the upper Midwest and northern Great Lakes region. Of
course biggest forecast challenge is determining just where that
heavy rainfall axis will ultimately set-up which still has quite a
bit of uncertainty particularly since it involves convection.
Guidance consensus trends in the last day have shifted that focus
just a bit northwestward with the axis of heavy rainfall largely out
of lower Michigan at this juncture. This forecast will nudge toward
that idea with some subtle shifts in pop/quantitative precipitation forecast values. But given the
very moist airmass/slow moving front and prolonged rainfall...
potential is certainly there for some areas to receive greater than
2 inches of rainfall through Saturday night across the far northern part
of this County Warning Area.

Friday...first bout of rainfall looking to develop and spread up
into northern Michigan Friday morning as initial Theta-E plume gets
shoved up into the region. Again...latest guidance consensus
suggests the strongest portion of the low level jet forcing/
qg-upward support and highest rain chances will initially align from
Wisconsin up across Upper Michigan on Friday with rain chances/
amounts quickly diminishing across northern lower Michigan toward Saginaw
Bay. This forecast will feature a bit of a northwestward shift in
probability of precipitation/quantitative precipitation forecast over previous forecasts which again may be the trend for
this event.

Friday night...initial warm/moisture surge complete by Friday night
and much of lower Michigan may find itself on the drier side of
things as incoming cold front slowly advances through western Upper
Michigan while short wave rides up along the front. Certainly
appears that the main focus for precipitation and highest rain
chances/highest amounts will line up in the vicinity of the front
across Upper Michigan and perhaps just down into northwest lower Michigan/
tip of the mitt...with diminished chances across northern lower Michigan
toward Saginaw Bay.

Saturday and Saturday night...short wave trough/attending surface low
and slow moving front finally slides across northern Michigan during the
day Saturday bringing more rain chances to the north and increased
rain chances for the southern part of the County Warning Area. Will stick with
categorical rain chances for the entire County Warning Area during the day with
precipitation tapering off Saturday night as the front slowly clears the

Sunday...shaping up to be the better day overall across northern Michigan
for this Holiday weekend. Short wave continues northeast into Canada
while intervening surface high pressure and wedge of drier air move
across the western Great Lakes. Lingering moisture/daytime heating
could spark a few showers during the day but I think the chances are
looking less and less and plan to go with a dry forecast.

Labor Day...unfortunately comes round two just in time for Labor Day
and all the associated festivities. Second short wave trough and
attending surface cold front makes it/S way across the northern plains and
into the Great Lakes region pulling another axis of higher dewpoint
air into the region before frontal passage later in the day Monday. Timing is
everything of course and right now...guidance timing suggests precipitation
doesn/T develop in the area until later Monday morning and into the
afternoon which would be good news for the bridge walk. But that is
four days out and will not get cute with forecast timing at this
point and those participating in the bridge walk should plan on
bringing rain gear.

Tuesday through Thursday...a nearly zonal flow pattern reestablishes
across the Continental U.S. To wrap up the extended part of the forecast...with
broad weak high pressure across the Great Lakes. An overall dry
stretch of weather through this time with temperatures warming back
to around normal.


Aviation...(for the 06z tafs through 06z Friday night)
issued at 1147 PM EDT Thursday Aug 28 2014

Light rain Friday morning/midday. Mainly VFR.

High pressure presently over southern Ontario Michigan will move east.
Moisture will quickly surge northward into the region behind the
high. -Ra is expected to arrive at all taf sites Friday
morning...and will diminish after several hours. Small chance for
MVFR ceilings...especially toward the tail end of the rainy
period...but for now the tafs will contain only VFR conditions.

Light winds tonight...a bit of a southeast to S breeze Friday.


issued at 354 PM EDT Thursday Aug 28 2014

Marine...surface high pressure exits east tonight...ahead of low
pressure and a warm front lifting toward the western Great Lakes.
Southerly winds do increase...while over lake instability weakens.
Conditions then turn increasingly stable over the lakes Friday into
Friday night while low level winds ramp up more significantly.
Foresee some gusts to around 20 knots or so developing and there is
a chance that some Small Craft Advisory winds to develop Friday into
Friday night across all nearshores...especially Lake Michigan and
Whitefish Bay. A frontal boundary and weaker pressure gradient
expected to move in Saturday into Saturday night.

Rain and a chance for thunderstorms are likely Friday into Friday
night...and likely into Saturday as well.


Apx watches/warnings/advisories...



long term...Adam

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