055
FXUS63 KDTX 200822
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
422 AM EDT Mon May 20 2024

.KEY MESSAGES...

- Very warm and muggy conditions continue for the next several days.

- Showers and thunderstorms develop this afternoon with highest
  confidence for broader coverage north of I-69.

- Brief heavy downpours, gusty winds, and small hail are the main
  concerns today, although an isolated storm could approach severe
  wind or hail thresholds.

- Additional storms are possible Tuesday afternoon followed by a line
  of strong to severe storms late Tuesday night which poses the
  greatest threat for 50+ mph gusts.

- One more chance for showers/storms Wednesday before a cooler and
  less humid airmass arrives for the rest of the workweek.

&&

.DISCUSSION...

Shortwave trough shearing off the southern stream jet and coincident
with an MCV over Missouri will continue to progress/decay
northeastward this morning. The convectively augmented wave takes
aim at northern Lake Michigan while another day of anomalous warmth
bears down on Southeast Michigan. In the absence of airmass
modification, expect the combination of afternoon dewpoints in the
low-mid 60s and high temperatures the mid-upper 80s to result in
SBCAPE values of 1750-2250 J/kg, mirroring the previous day`s SPC
mesoanalysis data. While the low-shear/high-CAPE setup drives the
prevailing forecast narrative, some enhancement to shear profiles
arrives later in the day north of I-69 with the approach of the
aforementioned remnant wave. Although surface-based convective
storms are possible across the entire forecast area this afternoon
and evening, locations along/north of M-46 are favored for enhanced
storms given proximity to improved shear profiles and positioning
along the PWAT gradient. This offers the best chance for severe-
adjacent cells. Localized outflow boundaries intersecting pockets of
higher instability may suffice in the production of hail approaching
1 inch in diameter or gusts to 50 mph. Uncertainty exists regarding
the persistence of nocturnal convective activity as elevated
instability lingers until approximately midnight.

Interfacing of the polar and subtropical jets amplifies a speed max
over the central Plains Tuesday. This drives a deepening surface low
into southern Minnesota while the southerly flow within its broad
cyclonic shield pushes the resident surface boundary northward
across the MI/OH border. Dewpoints respond to the ThetaE plume with
most locations crossing into the mid-60s, but forecast soundings
indicate a slightly capped thermodynamic structure given the warm
frontal boundary. Still expect some degree of afternoon convection
as shear vectors improve with ample MUCAPE.

Main event looks to arrive late Tuesday night into Wednesday morning
as the system`s cold front races through Lower Michigan. Potential
exists for an organized QLCS to accelerate through the area ahead of
the front which poses a strong to severe wind threat. Latest SPC
SWODY2 includes a combination of Marginal (1/5) to Slight (2/5) Risk
for isolated to scattered severe events.

The upper level pattern undergoes major adjustments Wednesday as an
energetic low drops into the Pacific Northwest triggering down
stream ridge amplification. An orphaned upper low parked over
Saskatchewan dampens the height rises, but it still unlocks the
stalled eastern Plains jet axis. One more dose of CVA triggers a
secondary convection response Wednesday before the more potent cold
front clears through Wednesday night. Post-frontal conditions should
be noticeably drier and cooler for the latter portion of the
workweek as temperatures and dewpoints drop by roughly 10F and 15F,
respectively.

&&

.MARINE...

Weak winds this morning organize predominantly out of the southeast
today as a warm front lifts across the region in response to low
pressure tracking in from the Midwest. This system brings an
increasing coverage of showers and thunderstorms this evening into
tonight, especially across northern/central Lake Huron closer to
where the center of the low is forecast to track overnight.
Conditions are expected to remain below Small Craft Advisory
criteria, though locally higher winds and waves will be possible
within any thunderstorms. A stronger low develops over the Plains on
Tuesday, lifting into western Lake Superior on Wednesday. Winds
increase out of the south to 20 to 30 knots ahead of the associated
cold front Wednesday, then veer to the west Wednesday night into
Thursday while remaining gusty to around 25 knots. Less humid air
settles in for the late week as high pressure builds in.

&&

.CLIMATE...

Here are the record high temperatures for May 20th through
May 22nd:

May 20th:
Detroit                91 (set in 1977)
Flint                  92 (set in 1934)
Saginaw/Tri-Cities     93 (set in 1977)

May 21st:
Detroit                92 (set in 1977)
Flint                  93 (set in 1921)
Saginaw/Tri-Cities     94 (set in 1977)

May 22nd:
Detroit                90 (set in 1994)
Flint                  91 (set in 1934)
Saginaw/Tri-Cities     89 (set in 1992)

Here are the record high low temperatures for May 20th
through May 22nd:

May 20th:
Detroit                68 (set in 1934)
Flint                  65 (set in 1939)
Saginaw/Tri-Cities     70 (set in 1975)

May 21st:
Detroit                71 (set in 2013)
Flint                  67 (set in 1934)
Saginaw/Tri-Cities     66 (set in 2021)

May 22nd:
Detroit                67 (set in 1941)
Flint                  65 (set in 1977)
Saginaw/Tri-Cities     68 (set in 1977)

&&

.PREV DISCUSSION...
Issued at 1151 PM EDT Sun May 19 2024

AVIATION...

VFR conditions will prevail into early Monday afternoon with just a
short period of minor fog possible early in the morning. Scattered
showers and thunderstorms will be possible from mid/late afternoon
into early evening. Additional activity may also funnel into the
area into Monday night, but confidence in timing/location in low.

For DTW/D21 Convection...Isolated to scattered thunderstorms will be
possible again late Monday afternoon into Monday evening. Strong to
locally severe storms will be possible. While confidence is low in a
storm actually impacting the terminal, the strongest storms will be
capable of gusty winds, hail and very heavy downpours. Storm motion
will be west to east at 30-40 mph.

DTW THRESHOLD PROBABILITIES...

*  Low for thunderstorms after 20z-22z Monday afternoon.


&&

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

$$

DISCUSSION...KGK
MARINE.......TF
CLIMATE......KGK
AVIATION.....DG


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