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Area Forecast Discussion
514 FXUS64 KHUN 282303 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 603 PM CDT SAT MAY 28 2016 .UPDATE... For 00Z TAFs. && .DISCUSSION... (Issued 235 PM CDT SAT MAY 28 2016) Latest water vapor imagery shows an upper level low shifting to the north-northeast across the Great Plains, while Tropical Depression 2 makes its way towards the South Carolina coast. In between these two low pressure systems, a convergence axis was located parallel and just east of I-65 over the TN Valley. This, along with an influx of moisture, has allow for showers to continue to develop and move in a northward motion across a narrow axis in eastern Alabama and central TN. Radar trends support short term guidance in that the activity will slowly shift eastward and dissipate towards the evening hours. Meanwhile, extensive dense cirrus was holding across the forecast area, keeping our temperatures several degrees cooler than those yesterday. Thus, the lack of thunderstorm activity. The Great Plains surface low will continue to shift to the north- northeast overnight, sending a series of weak shortwaves through region. Lift will be meager, and with little instability during the day, showers and thunderstorms are not anticipated to develop overnight. Meanwhile, the axis of the upper trough will flatten, leaving zonal flow over the forecast area on Sunday. While the probability of thunderstorm develop remains low, given the uncertainty of mesoscale conditions, have kept in a low 20 pop in the forecast for Sunday afternoon. The greatest chance for thunderstorms, though still isolated in nature, will be across the eastern portion of the forecast area once again, where another convergence zone is forecast to develop and moisture will be greatest. The remainder of the forecast period, through next Friday, remains relatively similar each day. Weak shortwaves will continue to move in the weak zonal flow aloft and any boundaries will provide a focus for convection. Upper level ridging will begin to build in on Tuesday, providing our warmest temperatures over the next 7 days. Meanwhile, an upper level trough will slowly move east of the Rockies by mid week, with a cold front developing south of the surface low. This system will approach the forecast area late Wednesday. As moisture increases ahead of it, thunderstorm chances will also increase, with the highest chances expected Thursday through Friday, as the front moves across the area. With this being so far in the extended, didn`t feel confident enough to add the likely pops and therefore adjusted the pops down by a few percentages. Temperatures late in the extended will be near seasonal and highly dependent on any precip that does occur. 73 && .AVIATION... For 00Z TAFs: A weak upper wave will produce some sct shra/tsra mainly east of the taf sites until arnd 03z. After 03z the shra/tsra activity will dissipate across the TN Valley due to loss of day time heating. Sunday will be similar to today with only a slight chc of shra/tsra. Otherwise expect mainly vfr conditions thru the fcst period for both KMSL and KHSV. 007 && .HUN Watches/Warnings/Advisories... AL...NONE. TN...NONE. && $$ For more information please visit our website at weather.gov/huntsville.