Aviation Forecasts Discussions (AFD) INFO

(EXTRACTED FROM FXUS64 KFWD 160037)


    /00Z TAFs/
    
    VFR through Saturday with south flow returning. Rain begins
    late Saturday with the potential for IFR conditions.
    
    A surface ridge axis will slip across the TAF sites this evening,
    and the light southerly flow now across West Texas will invade the
    I-35 corridor. Aloft, a strongly sheared upper trough is resulting
    in moderate-to-severe turbulence FL150-250. This should abate as
    the feature is stretched into a col. Cirrus will spread northward,
    but VFR conditions will prevail into Saturday afternoon.
    
    As the upper low currently over the Mexican state of Sinaloa
    heads toward the Trans-Pecos on Saturday, southwesterly flow aloft
    will pull moisture from the tropical Pacific across the eastern
    half of Texas. With increasing south winds at the surface, the
    rich low-level moisture still in place across South Texas will
    surge northward, arriving in North and Central Texas late in the
    day on Saturday. Widespread showers will cross the Rio Grande and
    spread across the TAF sites by Saturday evening. Mesoscale
    guidance seems a bit fast with the arrival of the precipitation,
    but its onset will likely be sudden. This will mean a rapid
    transition to MVFR ceilings and intermittent rain. Lapse rates
    within the precipitation-bearing layer still appear too weak to
    support thunder. If the rain is nearly continuous, conditions may
    deteriorate more quickly than the current TAF advertises, and IFR
    ceilings may prevail during the mid to late evening hours. A
    strong surge of mid-level dry air should abruptly shut off the
    rain Saturday night, perhaps in the 06-09Z (midnight-3am CST) time
    frame.
    
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