869
FXUS63 KDTX 121647
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1247 PM EDT Mon Aug 12 2024

.KEY MESSAGES...

- Seasonable temperatures through the mid week period.

- Isolated showers possible today and Tuesday.

- Rain chances increase Friday into the weekend.

&&

.AVIATION...

SE Mi remains on the eastern fringe of broad Midwest high pressure
this afternoon. Cooler air still over the region gets a boost from a
mid level wave and daytime heating for production of VFR cumulus. An
isolated shower is also possible nearby the terminal corridor but
with low predictability for any specific location. High pressure
then builds more strongly overhead tonight and Tuesday. A brief
period of ground fog is possible around sunrise leading up to
another round of afternoon VFR instability cumulus.

For DTW/D21 Convection... The weather pattern does not support
thunderstorms today through Tuesday.

DTW THRESHOLD PROBABILITIES...

*  Low for cigs at or below 5000 ft this afternoon and evening.

&&

.PREV DISCUSSION...
Issued at 310 AM EDT Mon Aug 12 2024

DISCUSSION...

Mid level cyclonic flow gradually relents today, as height falls
associated with a seasonably strong closed low over Quebec finally
release eastward. General transition toward confluent mid level
northwest flow atop weak high pressure suggests a higher degree of
stability will exist across the column today. With that, daytime
heating offers a window for shallow instability to emerge, with a
couple hundred joules of CAPE targeted for the late day period. This
may prove sufficient to yield isolated showers, highlighted
primarily along the US 23 corridor given a noted weak signal of
convergence. Plausible nothing develops as moisture quality remains
lean within a moderately mixed profile. Temperatures take step
upward within the backdrop of an increasing upper height field. Late
day readings arriving closer to average, with humidity remaining
manageable.

Conditions largely a carbon copy for Tuesday. Loosely organized high
pressure beneath persistent northwest flow ensures thermal advection
remains muted, maintaining a seasonable mid August thermal profile.
Potential for a modest uptick in larger scale vertical motion as
shortwave energy works through the great lakes offers slightly
greater convective shower potential during the peak heating cycle.
Still not a great signal overall across short range model guidance,
but the underlying thermodynamic profile again affords a weakly
unstable profile as lapse rates steepen diurnally. Forecast maintains
an isolated mention attm.

Upper ridging takes control for the Wed-Thu window. No significant
weather noted this period given depth of stability within this
environment. An increase in the upper height field portends
additional moderation of the existing airmass, but still no evidence
of a more sizable warming trend with low level flow still backed to
the southeast and cloud cover likely an increasing issue by
Thursday. Attention Thursday night into Friday turns to an initial
period of forced ascent and accompanying moisture advection
associated with an organizing height fall center propagating toward
the upper great lakes. Improving confidence evident within the model
solution space for a meaningful response locally during this
timeframe, offering an increasing probability for shower and
thunderstorm production within the background of concentrated ascent
above 850 mb. Potentially unsettled conditions heading into the
weekend, as pv consolidates into a more organized low nearby and
engages an increasingly moist and weakly unstable profile during
this time. Positioning and downstream pace of the governing large
scale features will dictate the scope and timing of any prospective
convective episodes.

MARINE...

High pressure will continue to build northward across the region
today pushing the last bit of influence from the Quebec low out of
the Great Lakes. More stable conditions with ridging aloft and at
the surface should produce favorable marine conditions across the
waters through mid week with max wind gusts mostly below 10 knots
and minimal wave heights.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...None.
Lake St Clair...None.
Michigan waters of Lake Erie...None.
&&

$$

AVIATION.....BT
DISCUSSION...MR
MARINE.......MR


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