Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
FXUS63 KDTX 280649
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
249 AM EDT SAT MAY 28 2016
Upper level ridge over the Eastern CONUS will amplify into this
evening as low pressure opens and lift NNE from the central plains
to the upper Mississippi Valley. Heights build slightly over the
region due to this amplification, so expect warm/humid conditions to
persist. High temperatures should reach the mid/upper 80s in most
locations with heat indices a couple of degree warmer than that as
surface dew points hold in the middle 60s throughout the day.
The 00z model consensus suggest there will be a better chance of
showers and thunderstorms across the area from early afternoon into
early this evening. That said, most of the forcing mechanisms
associated with the low pressure system to the west will, indeed,
remain west of the region. This suggests a strong diurnal component
to convective activity, which should be rather disorganized given a
decided lack of any substantial focusing/forcing. This supports a
time window centered on the afternoon hours with a general 40 to 50
percent chance of precipitation as scattered showers/thunderstorms
evolve across lower Michigan with the warm/humid air mass in place.
As this low pressure system continues northeast into the northern
Great Lakes on Sunday, a weak cold front will progress west to east
into the area and provide another chance of scattered to perhaps
numerous showers/thunderstorms during the afternoon/early evening
hours. Activity may be a bit better organized as the cold front
provides additional convergence/lift to focus a moderately unstable
atmosphere. However, bulk shear values remain rather low per model
forecasts (perhaps 20 knots in the 0-6 km layer), so convective
organization may still be rather iffy and generally multi-cellular
in nature. Still, with moderate instability in place and at least
some degree of focus, suspect a few stronger storms will be possible
over lower Michigan even if overall coverage remains AOB 50 percent.
Surface high pressure will build west to east through the area in
the wake of this cold front early next week, providing generally dry
weather. Temperatures will still be on the warm side, 80-85 degrees
away from the immediate Great Lakes shoreline, but lower humidity
values will make for more comfortable conditions and cooler nights
as low temperatures fall into the mid 50s to lower 60s.
Humidity will begin to build again to some extent by the Wednesday
and Thursday time frame as broad southwest flow once again becomes
establish in advance of next organizing low pressure over the plain
states. The chance of scattered showers or thunderstorms will also
return to the area with the approach of this next system with cooler
and drier conditions likely heading into next weekend once this low
pressure system passes to the east/northeast and an amplifying upper
level trough within the northern stream allow a more substantial
surface high pressure system to build SE into the area from Canada.
Areas of dense fog will remain likely over much of Lake Huron
through Saturday night as a warm and humid airmass continues to
reside over the cold lake waters. Otherwise...winds will turn more
southerly and increase slightly today into tonight as low pressure
lifts just west of the Great Lakes. The warm airmass over the area
will continue to support a chance for showers and thunderstorms
through Sunday night. The best coverage of showers and thunderstorms
is expected late Sunday and early Sunday night as a cold front moves
across the region. A few of these storms may be strong or even
severe. Winds will turn westerly behind the cold front for Memorial
Day. A drier airmass should also end the threat for thunderstorms.
Issued at 1157 PM EDT Fri May 27 2016
SE Michigan terminals will remain largely east of the main corridor
of thunderstorm activity through this TAF period. There will
continue to be a lower probability of development, particularly
across MBS/FNT Saturday afternoon. However, uncertainty in both
coverage and timing will preclude any defined mention at this stage.
Otherwise simply residual mid/high cloud for tonight, with some
renewed high based cu for the daylight period Saturday. Winds to
maintain a southerly component through the period. This gradient
will limit fog potential tonight, brief MVFR conditions at worst.
//DTW Threshold Probabilities...
* Moderate for ceiling at or below 5000 FT on Saturday
* Low for thunderstorms affecting DTW/D21 airspace through Saturday
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
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