Area Forecast Discussion
Issued by NWS Huntsville, AL
Issued by NWS Huntsville, AL
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447 FXUS64 KHUN 120625 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 125 AM CDT Wed Jun 12 2024 ...New AVIATION... .NEAR TERM... (Rest of tonight) Issued at 942 PM CDT Tue Jun 11 2024 Winds have decoupled in many areas in northwestern Alabama. Expect this to occur in southern middle Tennessee, as a weak trough axis at the surface moves southeast this evening. As this trough axis shifts further southeast, it should re-enforce very weak advection of slightly drier air into the area as it does so. Models do move this feature back to the north during the morning hours on Wednesday, but not before then. Some thin high clouds can seen in satellite imagery moving northeast through the area, but they are moving quickly northeast and are very thin and high in nature. We are not expecting them to have much impact. This should have little impact on radiational cooling conditions this evening given light winds already, which should continue. Some scattered lower clouds could affect portions of northeastern Alabama towards and after daybreak. However, they should remain scattered at best until around 7 or 8 AM, when they could become more widespread. Temperatures have already dropped into the lower to mid 60s in many locations. The exceptions to this are mainly in the Quad cities areas and locations that still have northerly winds around 5 mph in north central Alabama. Given some dewpoint depressions are already 5 or 6 degrees and good radiational cooling is expected overnight, introduced patchy areas of fog after 2 or 3 AM into the forecast. This could become areas of fog briefly around daybreak, mainly west of the I-65 corridor and in sheltered valley locations. Not expecting dense fog at this time. Overall lowered temperatures and dewpoints slightly overnight. Lows should likely drop into the 51 to 54 degree range west of the I-65 corridor and in a few sheltered valley spots further east. Otherwise, lows in the mid to upper 50s are expected. && .SHORT TERM... (Wednesday through Friday) Issued at 327 PM CDT Tue Jun 11 2024 A dry trend should continue for the remainder of the work week, as the airmass in the aformentioned surface high moderates from a strong June sun. Highs on Wednesday should rise into the mid/upper 80s under generally sunny skies. A warming trend will continue as we near the upcoming weekend, with lows Wed night in the lower 60s. Summer conditions return Thursday with highs rising into lower 90s. Even warmer temperatures are forecast Friday, with highs heating into the low/mid 90s. && .LONG TERM... (Friday night through Monday) Issued at 327 PM CDT Tue Jun 11 2024 Not many changes made with the extended period. A surface high over the eastern CONUS will stagnate even more as we go into the weekend. Strong and warm upper ridging will also build over the region, with 500mb heights rising to and above 590 decameters from Saturday into early next week. This and more sun than clouds will likely create a rather hot weekend. After lows Friday night in the mid 60s to lower 70s, highs Sat will soar into the mid 90s. Even warmer Sunday with highs in the mid/upper 90s. Heat Index values on Sat should rise into the mid 90s to 100, and upper 90s to 105 on Sun. The 105 readings were spotty over parts of NW Alabama. Previous discussion 408 AM... The center of the mid-level high is predicted to become centered directly across the TN Valley by Saturday, with the warming trend continuing as mostly sunny skies during the afternoon will support highs in the mid 90s on Friday and mid/upper 90s on Saturday (but roughly 5-10 degrees cooler both days atop the Cumberland Plateau). Unfortunately, it appears as if low-level moisture will begin to pool ahead of a weakening cold front that will drift southward into the TN Valley before stalling on Friday afternoon/evening as the parent surface low ejects northeastward across Quebec, and the increase in dewpoints will result in heat indices in the 95-99F range Friday and 98-102F range Saturday. The 500-mb high will begin to shift east-northeastward into the NC/VA vicinity on Sunday and Monday, allowing for a gradual increase in deep-layer SSE flow across the TN Valley by early next week. Although this configuration will eventually contribute to gradual moistening of the atmospheric column (and a subsequent increase in clouds and showers) this will likely not occur by Sunday, and highs are forecast to reach the m-u 90s, with heat index values in the 100-105F range. We have indicated a low (20-30%) POP for showers and thunderstorms returning to most of the region Sunday night/Monday, and have indicated lower afternoon temps on Monday as a result of this. However, if the subtropical ridge remains more influential (as indicated by several global models), then the hot/dry pattern may continue for several additional days next week. && .AVIATION... (06Z TAFS) Issued at 125 AM CDT Tue Jun 11 2024 Winds at KHSV and KMSL should become lighter and drop to around 2 or 3 knots after 06Z. Dry air in place at the terminals should keep fog from forming. Winds will pick up and become more north- northeasterly after daybreak around 4 or 5 knots. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...None. TN...None. && $$ NEAR TERM...KTW SHORT TERM....RSB LONG TERM....70 AVIATION...KTW