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Area Forecast Discussion
286 FXUS64 KHUN 242330 AAA AFDHUN Area Forecast Discussion...UPDATED National Weather Service Huntsville AL 630 PM CDT FRI JUN 24 2016 .UPDATE... For 00Z TAFs. && .DISCUSSION... (Issued 324 PM CDT FRI JUN 24 2016) The 20z surface and satellite analysis indicated that temps were ranging from the mid to upper 80s across northeast Alabama and in southern middle Tennessee, to the lower 90s in northwest Alabama. The latest few IR/Visible satellite images indicated that there was still a decent amount of low to mid clouds across the region in the wake of the dissipated showers/storms along the weakening frontal boundary near the forecast area. The short term models are in decent agreement through early Saturday involving the forecast area being generally dry and very warm. The RAP/Hi-Res and HRRR models all dissipate any left over showers/storms by this mid evening and have dropped any mention of precip especially after the 02z time frame tonight. Will continue with the current trending of keeping temps, dew point temps and heat index values in generally in the 105-110 degree range for Saturday and Sunday afternoon. Will continue the heat advisory for the forecast area and have highlighted the high heat index values for the area via social media, forecast and on web site. Have also trimmed back the precip chances into the slight chance category for Saturday, as forecast soundings indicate a little more of a cap for Saturday. Expect slightly increased pops for Sunday east of Interstate 65 due to the combination of orographic effects and also a weak piece of short wave energy moving through northeast Alabama by the time of peak heating. The GFS/Ecmwf models are in decent agreement involving the timing of the weak cold front that is progged to move into the lower Ohio valley by 06z Monday. The cold front is then expected to sink southeastward into middle Tennessee by Monday afternoon and into the forecast area by late Monday afternoon/Monday evening. Will continue with higher chance pops across the forecast area due to the timing of the system moving into the region during peak heating, expected CAPE values around 2K, PWAT values around two inches and lifted indices approaching moderate instability values. Will linger lessening chances of showers/storms across the forecast area into Tuesday. By Wednesday, the GFS model is more pronounced with a southern push involving drier and cooler air in the wake of the cold front, as opposed to the lesser amount of cooler air expected by the ECMWF model. Have gone with a temp compromise at this point between the GFS and ECMWF model solutions for Wednesday and Thursday due to uncertainty of the southward progression of the cold front. With more of a southwesterly low level flow setting up by Thursday afternoon, have for now kept in a slight chance afternoon pop for the forecast area. By late Thursday and into Friday, the models are differing with respects to the southward movement of the next cold front out of the lower Ohio valley and into the forecast area. Will maintain a chance pop on Friday as the system moves into the region. TT && .AVIATION... For 00Z TAFs: VFR conds prevail for now at both main terminals. Weakening area of tsra out of srn mid TN moving into ne AL should remain clr of the airports, although an outflow boundary diving swd may tempo impact KHSV between 00-01Z resulting in brief gusty winds out of the n. Otherwise, weak frontal boundary moving swd into the area Sat will result in additional shra/tsra mainly during the afternoon hrs. Conds at the two main terminals may briefly drop into the MVFR cat in/near any shra/tsra. 09 && .HUN Watches/Warnings/Advisories... AL...Heat Advisory from 10 AM Saturday to 4 AM CDT Monday for ALZ001>010- 016. TN...Heat Advisory from 10 AM Saturday to 4 AM CDT Monday for TNZ076-096- 097. && $$ For more information please visit our website at weather.gov/huntsville.