Area Forecast Discussion
Issued by NWS Huntsville, AL
Issued by NWS Huntsville, AL
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773 FXUS64 KHUN 202256 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 556 PM CDT Thu Jun 20 2024 ...New AVIATION... .NEAR TERM... (Tonight) Issued at 316 PM CDT Thu Jun 20 2024 A fairly widespread cumulus deck has kept temperatures a bit cooler than expected so far today. Temperatures currently are in the upper 80s to around 90 degrees. Models hint that this cumulus field might lessen in coverage around 4 PM. This could allow highs to still reach the 92 to 94 degree range in some locations. This cumulus field should dissipate quickly after sunset, as a large area of high pressure to our northeast continues to build southwest into the area. This will allow for very light if not calm winds to develop tonight. This should allow for good radiational cooling conditions. Thus, went slightly below guidance for lows tonight. Not going too far below guidance for lows given a weak pre-frontal trough axis may be able to focus an axis of higher low level moisture into the center of the ridge south into the area near and west of the I-65 corridor. Some lows in the mid to upper 60s seem reasonable near and east of the I-65 corridor. Elsewhere, expect lows to drop only into the upper 60s to lower 70s. For now, fog was left out of the forecast overnight. && .SHORT TERM... (Friday through Sunday) Issued at 316 PM CDT Thu Jun 20 2024 The big forecast feature will continue to the be the large area of high pressure that settles southwest into the Tennessee Valley through the weekend. A couple models to show some 700 mb and 300 mb higher relative humidity values, possibly associated with some cloud cover near the pre-frontal trough axis mentioned earlier that doesn`t move much. Otherwise, we would likely be looking at more widespread upper 90s Friday through Sunday. Also, the ridge itself will slowly weaken as the center of it shifts further southeast through that period. Having said that, widespread lower to mid 90s still look probable with some upper 90s possible by Sunday. With dewpoints in the 65 to 70 degree range, heat index values will likely climb above 100 degrees, but just shy of 105 degrees. Still be aware and careful if working outdoors and stay hydrated. If this cloud cover does not pan out, then temperatures could be a few degrees warmer than the current forecast. This would likely push heat index values into Advisory criteria if this occurs. && .LONG TERM... (Sunday night through Thursday) Issued at 316 PM CDT Thu Jun 20 2024 Latest extended range models indicate that this area of high pressure continues to shift WSW and centered across AZ/NM at the by Sunday night. Latest guidance shows precipitation ahead of an approaching front staying north of the area until the evening hours on Sunday. However, enough cloud cover may make it into the area in the mid/late afternoon hours to produce enough cloud cover to keep highs a bit lower than previously thought. Highs should still make it into the 95 to 98 degree range in most locations. Low chance PoP (20-30%) was kept in the forecast starting Sunday evening as the front moves into the area. This front weakens and slows down on Monday morning. Despite that kept a 20 PoP in the forecast on Monday. Due to expected cloud cover expect highs to be tempered slightly, but still should reach the lower to mid 90s. With a more moisture boundary layer with the front still departing the area, heat index values may reach 105 degrees in a few more locations. During the period from Tuesday-Wednesday, guidance suggests that the frontal boundary will begin to lift northeastward in response to another northern stream trough and related surface low moving eastward across Ontario/Quebec. The introduction of light SW flow/richer low-level moisture, coupled with less influence from the subtropical ridge aloft, should allow for a greater coverage of afternoon/evening showers and storms both days, along with slightly cooler afternoon high temperatures. && .AVIATION... (00Z TAFS) Issued at 556 PM CDT Thu Jun 20 2024 VFR conditions will prevail at both terminals for the duration of the TAF period. The scattered lower cloud deck will erode as the sun sets with clear skies and light and variable winds developing overnight through the day tomorrow. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...None. TN...None. && $$ NEAR TERM...KTW SHORT TERM....KTW LONG TERM....KTW AVIATION...RAD