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(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
    Thursday afternoon.
    
    PREV DISCUSSION...
    Issued at 327 PM EDT Wed Oct 23 2019
    
    DISCUSSION...
    
    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.
    
    MARINE...
    
    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.