Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
FXUS63 KDTX 281951
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
351 PM EDT THU JUL 28 2016
Very muddled pattern over the Great Lakes today. Large closed 500mb
low over northern Quebec has a trough axis extending southwest
through the western Lakes. In the meantime Large surface high
pressure centered over Manitoba has surface pressure axis extending
into lower Michigan under the low axis. This is producing broad
northeast flow into the area advecting drier boundary layer air. A
diffuse frontal boundary around 850mb that produced showers across
this area earlier in the day is settling southward with just broken
to scattered clouds.
Challenge with forecast is chances and coverage for any precip the
rest of today through Saturday. Cu build up this afternoon has been
suppressed by drier more stable northeast flow and cirrus passing
overhead from the south. Cape values range from a 100 joules in the
Thumb to around 1k along the Ohio border were dew points remain in
the upper 60s. Weak warm air advection in the mid levels has also
been providing weak capping. Most convection today around the lakes
has been occuring from lake breezes off of lake Michigan. Moderately
strong northeast flow has eliminated lake breeze boundaries over the
area today. Will still carry small to slight chc the rest of this
afternoon and evening for convection...mainly western and southern
parts of forecast area as any meso convergence could Early break
Tonight through Saturday night models indicate weak pv maxes to
eject out of trough axis to the west from time to time. Different
models show different strength, timing and location of pv maxes
ejecting out so will carry small chance all locations through
period. Instability will remain on the low side with best and
deepest moisture across the western and southern periphery of the
forecast area. Highs will be several degrees lower then todays
Friday and Saturday as northeast flow will remain.
On Sunday, heights will begin to rise slightly as the broad trough
axis shifts east. This will promote a mainly dry forecast, although
with lack of a strong subsidence signal can`t rule out a diurnal
shower/storm or two. More concerted height rises occur Monday
through Wednesday, which will result in a warming trend from the
near-normal values on Sunday. Moisture advection looks to stay out
to the west until at least mid-week, favoring a dry forecast locally.
Small craft advisories remain in effect for persistent fresh onshore
flow and elevated wave heights in the nearshore zones of Lake Huron
through Friday. Maximum wave heights in excess of 6 feet will be
found in the southern basin where fetch will be greatest. Moderate
east to northeast flow will continue through the weekend.
Issued at 1149 AM EDT Thu Jul 28 2016
Wind will persist out of the easterly to northeasterly quadrants
through the remainder of the forecast period. The exception may be
just a few hours this evening when a a combination of weak upstream
pressure falls and lake influences may veer wind to southeasterly in
the Detroit area. Ceilings will remain VFR with just a low chance
for a thunderstorm not worthy of a mention in the TAF, especially
due to the expected quasi-stationary nature of any tstorms that do
develop. In addition, cirrus canopy calls into question the
potential for destabilization to occur to begin with. Best potential
remains south and west of the SE Michigan airports.
For DTW...Primary aviation concern is noise abatement due to
northeast wind. Generally expecting wind to hold out of the NE above
7 knots through the day, perhaps veering to SE for a brief period
this evening. Slightly stronger NE wind expected on Friday. Second
concern is cigs around 5kft, which some guidance hints at this
morning. Cirrus canopy casts serious doubt on both cig and tstorm
potential, so will leave both out of the 18z TAF.
//DTW Threshold Probabilities...
* Low for tstorms impacting kdtw.
* Low for cig aob 5kft.
MI...Beach Hazards Statement until midnight EDT tonight FOR MIZ048-049-
Lake Huron...Small Craft Advisory until 10 PM EDT Friday FOR LHZ421-422-441>443.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
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