Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 271927

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
327 PM EDT FRI MAY 27 2016


Warm weather looks to carry through the weekend...with highs in the
80s and dew pts in the 60s.

Narrow ribbon of moisture/850-700 mb theta-e lifting north through
southeast Michigan between 21-3Z but within the backdrop of rising
500 mb temps/upper level ridging...which calls into question amount
of activity we will see. None-the-less, latest mesoscale
analysis(18z) indicates mlcapes nearing 1000 j/kg across Tri-Cities
region (north of I-69)...and still will need to be leary of an
isolated severe cell if activity goes up by early evening
hours...with over 30 knots of 0-6 km of bulk shear leftover and
high values of downdraft cape (in excess of 1000 j/kg) in place.

The large and strong upper level wave/low over the southern plains
will be the focus for our weather this weekend. Tomorrow, the
squeeze play will be on with the ridge to our east, as strong
southerly upper level flow setting up over the Ohio valley extending
to Gulf Coast States...allowing for upper level PV filaments to race
off to the north and converge on Michigan. One such piece of energy
(seen on dynamic tropopause) along the coast of Georgia/northern
Florida progged to break off and advance north toward southeast
Michigan late in the day. With the expected moderate diurnal
instability generated (mlcapes around 1000 j/kg once again)...this
feature should be just enough to trigger activity as moisture axis
(pw values around 1.75 inches) from the west also overspreads the
area...and planning on carrying high scattered activity into the
evening hours as height falls also begin to take place with the
Southern Plains wave/trough moving into the Western Great Lakes
Saturday Night. The trough axis will slide east into the Central
Great Lakes on Sunday, but there are big question marks on amount of
moisture left over as cold front slides through during peak heating.
The NAM is indicating 1000-850 mb capes of 2000-3000 j/kg...which
would support a severe risk. However...not sure we can count on
surface dew pts in the upper 60s at 21z. The Canadian model is
much drier...while GFS is a bit closer to the NAM. In any event,
based on the 00z euro, high scattered pops remain in order, but
severe chances look low/isolated at this point.

The condensed version...there will be varying chances of
showers/thunderstorms throughout the extended period.

Sunday night and Monday...a high pressure ridge will begin to build
over the Great Lakes region from the west giving the area somewhat
of a break from precip on Memorial Day. There still remains a slight
chance for some scattered showers on Memorial Day, though most areas
should be spared. Weak disturbances appear in the ridge on Tuesday...
ahead of the next weather system . This combined with the
continuation of above average high temperatures...could result in
some widely scattered showers Tuesday afternoon/evening. The next
low pressure system looks to be over SE MI by Wednesday afternoon.
Rain chances will bump up a bit through early Saturday morning as
the system pushes through area.



Areas of dense fog are likely to impact portions of Lake Huron
through the rest of the day today and into Saturday as a result of
the humid air coming in contact with the cold lake waters. Light and
variable winds today will transition toward light southerly winds on
Saturday as weak low pressure organizes across the upper Mississippi
Valley. This low pressure system will drift across the northern
Great Lakes on Sunday and will drag an associated cold front across
the region Sunday night. This system will provide a chance for
thunderstorms Sunday and Sunday night, while the passage of the
surface front supports a veering of the winds from SSW to west by


Issued at 1259 PM EDT Fri May 27 2016


The potential for late day thunderstorms once again is the main
aviation concern. The latest regional Radar loop shows some loosely
organized showers/thunderstorms lifting into far SW lower Mi and
south cntl Lake Mi. This area of convection is occurring within a
ribbon of higher low-mid level moisture and will lift northward into
the Saginaw Valley region late this afternoon. There will also be
some added low level convergence associated with a sfc trough draped
across the Saginaw Valley, enhanced by lake breeze convergence. Thus
the terminal with the highest potential for seeing late day
thunderstorms is MBS. Instability will be less farther south. Depth
of mid level dry air is also greater farther south and east of MBS.
So the MBS and possibly FNT TAFs only will carry a chance of late
day thunderstorms. The rest of the terminals may however see a
brief light rain shower late in the day as this mid level moist
plume lifts north. There will be another potential for
thunderstorms overnight, again with the better chances at MBS.
This will be the result of another influx of low to mid level
moisture within a weakly unstable environment. At this time,
chances of overnight thunderstorms appear too low to include in
the terminals.

FOR DTW...The depth of mid level dry air over metro Detroit and weak
daytime instability suggests the better chances for late
afternoon/evening thunderstorms will be well north of metro Airport.

//DTW Threshold Probabilities...

* Low for ceiling at or below 5000 FT this afternoon and evening.

* Low for thunderstorms affecting DTW/D21 airspace this
  afternoon through tonight.


Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.



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