Area Forecast Discussion (AFD)
Issued by Huntsville, AL (HUN)
677 FXUS64 KHUN 162357 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 657 PM CDT Mon Jul 16 2018 .UPDATE... For 00Z TAFS. && .NEAR TERM...(Tonight) Issued at 248 PM CDT Mon Jul 16 2018 Rainfall has just about cleared out of the area as the earlier swath of showers/tstms continues to move into parts of east TN/north GA. There may not be adequate time for the airmass to recover enough for additional showers/tstms to develop thru the remaining afternoon hrs although the prob cannot be completely ruled out. Additional upper waves are forming upstream over AR, although whether these hold together or the trajectory brings them closer to the cntrl TN Valley area later tonight remains to be seen. For now, will maintain sct showers/tstms in the forecast this evening pending what course these disturbances actually take. If the wx across the area actually stays more quiet, some light fog is then possible overnight given the rainfall that occurred earlier today. The fog could certainly be more locally dense in the sheltered/valley locations and near bodies of water as is usually the case. This remains somewhat uncertain though and is not in the forecast at this point, but may need to be added later this evening. Temps should trend near seasonal heading into the overnight hrs, with lows mainly in the lower 70s for most areas. .SHORT TERM...(Tuesday through Wednesday night) Issued at 248 PM CDT Mon Jul 16 2018 Latest model suites are still hinting at a cold front dropping into the area out of the NW Tue and Tue night. This boundary should serve as a focus for additional sct showers/tstms into the day Tue, and continuing into the evening hrs Tue night. Little in the way of cooler air though is xpcted with this oncoming front, as afternoon temps Tue are still xpcted to climb toward the 90F mark. However, overnight lows going into early Wed may at least be a few degrees cooler with the frontal passage, with temps falling into the upper 60s/around 70F. Some slightly drier air may then filter into the area from the north in the wake of the front on Wed, bringing perhaps a temporary break in showers/tstms. The exception may be the far SW corner of the local area where slightly better convergence will be in place near the stalled frontal boundary. Unfortunately, no such break is xpcted with afternoon temps, with highs again around 90F for most locations. .LONG TERM...(Thursday through Sunday) Issued at 248 PM CDT Mon Jul 16 2018 An unsettled pattern will continue late this week into the weekend as a large, subtropical ridge deepens over the Southwest and a broad upper-trough develops over the Great Lakes and Northeast. This will place much of the Deep South, including the Tennessee Valley under prevailing northwest flow aloft. After a mostly dry day Thursday, the through will amplify and a stronger piece of energy move from the Northern Plains into the Ohio Valley. This feature will force another weak front into (or very near) the area on Friday, setting the stage for an active day on Friday and Saturday -- as this feature will serve as a focus for scattered to numerous showers and thunderstorms. With sufficient instability and at least some appreciable wind shear in place, the potential for some organized convection will exist along and ahead of this boundary. Given the continued very moist environment in place across the region, heavy rainfall and localized flooding issues will continue to exist with any of the activity later this week. Both the GFS, ECMWF, and Canadian model suites all generally show this upper-trough sinking SE into the Southern Appalachians and Carolinas Sunday into early next week -- taking the front with it. This would cut back on the precipitation chances late this weekend to more isolated to scattered thunderstorm activity, and yield some partial clearing. However, northerly flow would also help to maintain seasonable to slightly below temperatures in the upper 80s to lower 90s during this time period as well. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 656 PM CDT Mon Jul 16 2018 A rogue storm or two cannot be ruled out thru 01-02Z, but odds are too low to include. Otherwise, VFR conditions are expected thru 07-08Z, before giving way to fog formation at both KHSV and KMSL. Confidence is high in MVFR visibility, and even high enough in IFR to include a 3-4 hour TEMPO group at both KHSV and KMSL. Guidance hints at LIFR conditions but confidence is NOT high enough to include at this time. Any fog will take an hour or two to dissipate with VFR conditions resuming by mid- morning at the latest. There is a low chance that thunderstorms could form along a cold front over MO/AR and push SE into the area around/shortly after daybreak, but confidence is far too low to include at this time. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ NEAR TERM...09 SHORT TERM...09 LONG TERM...AMP.24 AVIATION...BCC For more information please visit our website at weather.gov/huntsville.