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Spartman

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  1. It's going to be one of those weeks that the sun will be in much shorter supply. The upcoming weekend doesn't look great, either. The only day we'll have any luck getting sun over the next several days will be Thanksgiving. Overall, a pretty dreary Thanksgiving week ahead, with a few days of rain and some days of suicide weather.

  2. IND AFD:
     

    .Long Term...(Saturday night through Friday)
    Issued at 259 PM EDT Fri Sep 22 2023
    
    A developing tropical low pressure system just southeast of the
    Carolinas is forecast to move northward onshore later today. This
    system should then slowly slide northward along the Atlantic
    seaboard and slow down. As it does so, it will largely prevent
    systems to our west from freely advancing eastward. As such,
    subsidence between the two will lead to relatively quiet conditions
    this weekend.
    
    Surface flow will primarily be influenced by the tropical system
    with surface winds out of the east or northeast beginning Saturday.
    This should allow for some weak cold air advection leading to a
    reduction in high temperatures through the period. Expect highs in
    the mid 70s for most locations as opposed to the lower 80s we are
    seeing today. Less-than-ideal radiative cooling conditions may help
    moderate low temperatures a bit and limit morning fog potential.
    
    Clouds begin to increase late Saturday and into Sunday as a west
    coast trough ejects into the Plains. Most guidance stalls and
    eventually breaks down the trough before it reaches Indiana.
    However, guidance is trending in the direction of a weak cut-off low
    developing from the dying trough and drifting eastward. Moisture
    appears limited with continued east/northeasterly flow at the
    surface, but enough forcing may be present for some isolated showers
    or thundershowers. As such, slight chance PoPs are introduced from
    Tuesday onward. Ensemble guidance is is better agreement with the
    formation of the weak cut-off low than its subsequent evolution.
    Forecast uncertainty therefore increases late in the week.
    
    Despite differences in guidance regarding the departure of the
    aforementioned upper-low...enough agreement exists for increased
    confidence in quieter weather by Friday/next weekend.

    Meanwhile, the ILN AFD:
     

    .LONG TERM /SUNDAY THROUGH FRIDAY/...
    Complex long-term period as the combination of the low pressure (TC
    Ophelia) and weak upper-level disturbances to the west meander over
    the Ohio Valley and surrounding regions through the entire period.
    Zooming out and examining the longwave pattern over North America
    reveals a longwave ridge axis extending well north over Hudson Bay
    late this weekend into early next week. This is largely due to a
    longwave trough becoming established over the northwest CONUS and
    western Canada. While there are uncertainties in the exact location
    of the feature, ensemble guidance (WPC clusters) are fairly
    confident in a closed or cut-off low becoming established over the
    region through midweek, before eventually evolving into a more
    classic Rex Block pattern (Ridge to the north with low to the south)
    by the end of the week.
    
    Due to the general weakness of the overall pattern described above,
    confidence is high that the Ohio Valley region will avoid widespread
    hazardous weather through the period. However, it does not appear
    the period will be rainfall free as has been the case for much of
    September. After the remnants of TC Ophelia dissipates, the
    breakdown of the circulation allows for the below normal PWAT
    anomalies to be replaced by above normal values. The values are not
    significantly high, but it does point to a likely day-to-day weather
    change, especially through midweek. Conditions are expected to be
    more cloudy, with occasional rain shower chances across the area.
    Expect high temperatures to be limited into the 70s due to these
    conditions.
    
    The high confidence regarding the overall pattern doesn`t result in
    high confidence for the daily rainfall forecast. This will be
    largely dependent on the location of the closed/cut-off upper low
    that eventually organized. At this time, the best chances are for
    Wednesday and Thursday, with ensemble guidance in agreement of a
    consolidated upper low in place. Over the next few days, the
    evolution of the pattern will continue, with chance of rainfall
    fluctuating up and down throughout much of next week.

     

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