Area Forecast Discussion
Issued by NWS Huntsville, AL
Issued by NWS Huntsville, AL
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733 FXUS64 KHUN 090850 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 350 AM CDT Thu May 9 2024 ...New NEAR TERM, SHORT TERM, LONG TERM... .NEAR TERM... (Early This Morning and Today) Issued at 330 AM CDT Thu May 9 2024 A mid/upr level shortwave embedded in quasi-zonal flow is instigating shower/thunderstorm development early this morning just to the north and west of the area. The activity is becoming oriented in general W-E fashion, which is concerning for a couple of reasons. First, the activity is oriented parallel to flow direction, leading to training of cells and raising concerns for localized flash flooding given the suitable moist environment (PWATs ~1.5 to 1.7 inches) and ample broad scale ascent. Second, the southern extent of the activity is aligned generally along an old boundary that was draped across the area from previous convection, thus potentially amplifying the low-level shear available. Due to the continuing risk for tornado development, a TOR Watch was just issued at ~300 AM CDT. Otherwise, cold pool development and the potential for localized congealing cold pools will provide a risk for strong/damaging winds along portions of the evolving line of thunderstorms. Some wind gusts in excess of 50 kts have been noted already earlier this morning. This activity will move across the area during the remainder of the morning, perhaps clearing to our ESE around midday. Nevertheless, people should remain aware of this second bout of precipitation moving into the area this morning, in case they`re out and about for clean-up and S&R activities. A break in activity is expected this afternoon and some clearing of clouds are expected to occur, with highs expected to warm mainly in the low/mid 80s across the area. && .SHORT TERM... (Tonight through Sunday) Issued at 330 AM CDT Thu May 9 2024 Another short wave is expected to pass across the region tonight, but the better dynamic lift is expected to be to our south. Isentropic progs indicate some lift/saturation aloft over our area during the evening, and peaking overnight. However, there is disagreement among regional/global models over the degree of saturation in addition to lift/instability. POPs were kept rather low (20s to 30s) for the nighttime period due to the uncertainty with the northern extent of precipitation. A shortwave trough digging southward into the Grt Lakes early this morning will phase with a Northern Plains trough and carve out a broader long wave trough in the eastern CONUS on Friday. As a result a cooler, continental air mass will move into the TN Valley late tonight and Friday. This eastern CONUS trough pattern will tend to be maintained through Sunday, with slightly cooler than normal temperatures through the period. Successive shortwave maxima rotating around the western flank of the parent upr trough could bring a bout or two of increased cloudiness, but chances appear too low for any RA/SHRA to include in the forecast at this time. && .LONG TERM... (Sunday night through Wednesday) Issued at 330 AM CDT Thu May 9 2024 A partially closed upr low in the West CONUS will be ejected eastward as heights begin to fall in the northern Rockies from late Sunday into Monday. Moisture advection/ascent ahead of the pending upr trough could begin to bring rain to the area as early as Monday morning. Instability will increase gradually on Monday, but forecast thermal profiles just appear marginally unstable at this time, limiting updraft strength and severe potential. This trough may become partially closed again as it makes its way eastward across the OH/TN Valley regions, with chances for showers/thunderstorms continuing into Wednesday. && .AVIATION... (06Z TAFS) Issued at 545 AM CDT Thu May 9 2024 A break in activity is occurring at present, but another line of SHRA with embedded TSRA is expected to cross the area towards daybreak. The latest timing given a synthesis of hi-res models and simple advection of current activity to our west indicates movement of this line into KMSL ~10Z and KHSV ~11Z. TAFS will feature IFR ceilings with MVFR vis, although ceiling/vis conditions could LIFR or lower if a heavy cell impacts a TAF site and amendments would be needed. Otherwise, partial clearing is anticipated around 17-19Z, with another possible round of SHRA/TSRA after ~10/0000Z. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...None. TN...None. && $$ NEAR TERM...KDW SHORT TERM....KDW LONG TERM....KDW AVIATION...KDW