(EXTRACTED FROM FXUS63 KDTX 240153)
Low pressure moves from northern Illinois through central Lower
Michigan and carries a pattern of showers across the region tonight.
Upstream observations support a continued mention of MVFR visibility
with the showers and then MVFR ceiling along and behind the trailing
cold front overnight and Thursday morning. Gusty southwest wind once
again today subsides quickly with sunset which opens a few hours of
LLWS south of the low track mainly across the PTK to DTW corridor
until just before or with passage of the cold front. The wind shifts
NW post front with a few hours of gusts near 20 kts while lingering
MVFR ceiling climbs into VFR by late morning. Clouds tend to scatter
during Thursday afternoon as high pressure builds in from the west.
DTW THRESHOLD PROBABILITIES...
* High for ceiling 5000 ft or less Thursday morning. Moderate
Issued at 327 PM EDT Wed Oct 23 2019
The stacked low has shifted northward and is now centered over
northern Ontario. The initial trough has rotated east of area
allowing a low amplitude shortwave ridge to slide through while the
broad surface ridge across the eastern conus noses into the region.
The dry airmass and good boundary layer mixing has kept breezy
southwest winds across the area with mainly clear skies.
There is a low pressure system currently over the central Plains
developing on the nose of a jet max digging through the backside of
the broad upper level trough. This will get picked up by the next
trough axis rotating around the stacked low and steered through Mid
MI tonight providing a period of rain. Models have been fairly
consistent with this system, with the jet increasing aloft entering
the confluent zone while a 40-50 kt low level jet lifts into MI.
This excites a band of fgen within the leading arm of warm advection
which looks to lift through the Saginaw Valley and Thumb primarily.
Could get some light activity as this forcing lifts north into
position but highest confidence remains north of I69. Minor
adjustments to current POP grids to continue to refine the narrow
band of forcing.
Cold front will get pulled through Thursday morning allowing high
pressure to build back across the region for the end of the week.
Longwave trough will be setting up over the Plains which will
prevent colder air from moving into the region resulting in a
continuation of the current near neutral temperature advection
pattern with WSW flow. This will be aided by mostly cloudy
conditions until the trough can push east later on Friday. Max temps
will remain in the 50s through this time.
A quiet day is in store for Saturday as elongated high pressure
centered over New England extends westward into the Great Lakes and
results in light easterly low-level flow locally. High clouds will
increase through the day as low pressure organizes over the lower
Ohio Valley, but any precip should hold off until the evening hours
as very dry mid-levels will take time to saturate with meager
forcing before around 00z. Mid-range model consensus depicts a 40-50
kt LLJ developing Saturday night but has the best forcing and WAA
(and resultant higher PoPs/QPF) displaced just to our east. The
subtropical origin of the incoming air mass will result in
seasonably high PWATs and potential for heavy rain if this forcing
shifts more to the west.
The midlevel shortwave responsible for the surface low pressure
moving into the Great Lakes Saturday night will weaken as it lifts
toward Lake Ontario by Sunday afternoon. However, depending on the
track of the low, a decent chance exists for some showers on Sunday
as deformation forcing wraps around the backside. Longwave troughing
over the Canadian Prairie will keep deep southwest flow over our
region with the jet stream just to our north and west through the
early week. Diffuse high pressure at the surface looks to keep rain
chances at bay during this period. The GFS is currently more
aggressive with a shortwave swinging around this trough and brings
shower chances as early as Monday night, but will lean more with the
Euro/Canadian solutions that have a slower progression and bring
higher rain chances in for the Tuesday to Wednesday period.
Southwest winds gradually diminish over the course of the evening
and overnight period as the pressure gradient slowly weakens with a
ridge of high pressure moving in this evening and weak low pressure
quickly sliding through Lake Huron tonight. Impacts will be minimal
with this low pressure, with just light showers across Lake Huron
late tonight into early Thursday. Gusts up to Small Craft Advisory
criteria may persist over the next few hours this afternoon, but are
not expected to be widespread or long-lived and will thus allow the
current advisories to drop off with this forecast issuance. The Low
Water Advisory will however remain in effect into tonight for the
Michigan waters of Lake Erie. High pressure will begin to ridge into
the area from the west for the late week period which will keep a
fresh westerly wind in place over northern Lake Huron through
Thursday; lighter winds and waves will result elsewhere.
02:58 UTC |
07:58 PM Pacific |
08:58 PM Mountain |
09:58 PM Central |
10:58 PM Eastern