868
FXUS63 KDTX 091750
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
150 PM EDT Thu May 9 2024

.KEY MESSAGES...

- Cooler temperatures (50s to low 60s) hold through Saturday before
returning to at or above normal Sunday.

- Next chance of showers and thunderstorms comes Saturday with the
passage of a compact low pressure system. Severe weather is not
expected.

- Another chance of showers and thunderstorms comes Monday as a cold
front drops through the area.

&&

.AVIATION...

Low pressure is moving across the Ohio Valley this afternoon with an
area of rainfall on the north end now moving across Lower Michigan.
Rainfall will mainly impact PTK and the metro terminals. Northeasterly
wind to around 10 knots is present across Michigan with a high
pressure to the north helping pump in some drier lower level air.
This should keep hold predominately VFR conditions through today with
occasional MVFR conditions via lower CIGS or brief reduction VSBY
under any heavier shower. Will maintain VFR in TAFs and amened if a
better more prolonged MVFR signal develops. Rain clears out this
evening with any lower cloud largely clearing out tonight. Winds turn
more northerly for tonight with a return of lower VFR clouds by
tomorrow morning/afternoon supported by a cooler airmass settling
over the state.

For DTW/D21 Convection... Instability holds south of the state with
no observation of lightning thus far in southeast Michigan.
Thunderstorms remain unexpected through this afternoon and early
evening.

DTW THRESHOLD PROBABILITIES...

* Moderate in ceilings aob 5000 feet this afternoon and evening.

&&

.PREV DISCUSSION...
Issued at 305 AM EDT Thu May 9 2024

DISCUSSION...

Cold advection through the day today. The 00z APX raob indicated a 6
C temperature at 850 MB with a northeast wind. Low level northeast
winds will only increase and deepen (reaching 700 MB) through the
day, as 850 MB temps progged to reach 3-4 C over southeast Michigan,
which is still supportive of lower 60s. However, the cooler marine
layer off Lake Huron and thicker clouds and rain showers (south)
should lead to slightly cooler temps. The farther south trend
continued with the 00z NAM/regional GEM/RAP with the upper level
wave coming out of the Midwest. The corresponding 850 MB frontal
boundary now progged to reside over Central Indiana/Ohio with the
700 MB FGEN/shear axis not getting much past the southern Michigan
border. Will be going dry for M-46 northward, with pops then
increasing as one heads toward the southern Michigan border.

Positive tilted 500 MB trough axis to clear the State 9-12z Friday,
with short lived ridging building in during the daytime hours.
Still, the airmass starts out rather chilly (mins 40-45), 850 MB
temps around 1 C, and would not be shocked if isolated light showers
developed with the steepening diurnal low level lapse rates and some
modest cape (<100 J/kg) centered around freezing level. Ultimately,
will carry the silent 14 pop.

The next upper level wave is progged to move through far southern
Lower Michigan Saturday morning. This system is compact but robust
with the 500 MB low closing off at 547 DAM as the strong upper level
PV wraps around, and forcing looks to be maximized along and south
of M-59, as the 850-700 MB Theta-e ridge axis pivots and then sinks
south. Showers appear just about a done deal for southern two thirds
of the CWA, barring the system diving even farther south than
currently indicated. With the strong lift advertised over southern
areas and the showalter nearing zero, a slight chance of
thunderstorms also appears warranted. Conservative forecast for now
would indicated rainfall amounts near half an inch.

Good warm advection pattern kicks in for the end of the weekend, but
will have to be leery of the warm front activating and generating
showers and possible thunderstorms, best chance north of M-46. 850
MB temps reaching 10-12 C will allow for a warm Monday (70s), with
the timing and strength of a cold front being watched for potential
convection generation.

MARINE...

Low pressure tracks across the Ohio Valley today, with rain showers
flaring up along an elevated warm front through the morning. Shower
activity generally holds south of Harbor Beach. Easterly winds today
remain light which keeps wave heights aob 4 feet despite the onshore
component. Winds then veer to the northwest by early Friday morning
as high pressure attempts to build in from the north, leading to
drier conditions on Friday. This will be short-lived as the next low
pressure system traverses the broader troughing pattern aloft to
bring another round of rain chances for Saturday followed by high
pressure on Sunday.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...None.
Lake St Clair...None.
Michigan waters of Lake Erie...Small Craft Advisory until 10 PM EDT this evening for LEZ444.

&&

$$

AVIATION.....AA
DISCUSSION...SF
MARINE.......MV


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