textproduct: Columbia

WHAT HAS CHANGED

Minimal change to Key Message. Aviation discussion updated for 06z TAFs.

KEY MESSAGES

- 1. Thunderstorms expected each day through the weekend with seasonable temperatures. Drier conditions and warming temperatures are expected to start next week.

DISCUSSION

KEY MESSAGE 1: Thunderstorms expected each day through the weekend with seasonable temperatures. Drier conditions and warming temperatures are expected to start next week.

There has not been much change in the forecast with the latest round of model guidance. PWAT's remain between 1.80-2.0" across the FA early this morning with a few spotty showers in portions of the CSRA. Regional WV imagery reveals troughing setting up over the eastern CONUS with a shortwave moving through the southern Tennessee Valley. Overall, a fairly similar day to yesterday is expected with seasonable temperatures and scattered diurnal convection as MLCAPE values near 2000 J/kg. The severe risk is low, but it is worth noting RAP/HRRR/RRFS soundings indicate near 30 kts of cloud layer shear should be in place this afternoon as enhanced mid/upper level flows moves in. This could allow a few storms to sustain themselves and bring a low end risk for a couple strong to damaging wind gusts or an instance of sub-severe hail given slightly lower than normal freezing levels. localized flash flooding will be possible as well with efficient rain rates expected in convection.

Much of the same is expected Friday, except a front nearing the area through the day could aid in bringing a more focused area for convection during the afternoon/evening, especially toward the northern parts of the FA. A couple strong to severe storms will be possible once again as effective shear values near 20-25 kts with another shortwave moving in. Temperatures likely remain near normal through the weekend as the region now finds itself on the western periphery of the upper trough, but diurnal convection is expected each day. A bit of a pattern shift is then expected early next week as a strong ridge currently over the western US slides eastward, strengthening toward the NAEFS 97.5th percentile. This feature should bring lower rain chances, but temperatures 5-8 degrees above normal could be possible as seen in NBM IQR ranges. Returning heat indices above 100F could be possible as well with LREF probabilities between 50-60% by Tuesday.

AVIATION /06Z THURSDAY THROUGH MONDAY/

Restrictions associated with fog/stratus are expected to develop overnight into the morning. Additional restrictions from afternoon convection will be possible Thursday afternoon/evening.

Radar showing minimal to no rain at issuance time, but can not completely rule out an isolated shower overnight at any location. Bigger issue though is the expected development of low stratus and fog. With plenty of low-level moisture in place from earlier rainfall across the area, light winds, and somewhat clear skies, expecting to see initial development of low-stratus, which is currently beginning to show up on satellite. This will become rather widespread, with ifr ceilings impacting all taf locations by 08z. Guidance also shows the potential for period of ifr/lifr visibilities towards morning, and will handle that with tempo groups for now around sunrise. Ifr restrictions will last through 14z, then improving to mvfr, before finally back to vfr by 17z. Scattered convection is once again expected by the early afternoon, most likely between 17z through 23z or even slightly later. Activity should be diminishing by 02z, with isolated showers still possible through midnight again.

EXTENDED AVIATION OUTLOOK... Restrictions possible from showers and thunderstorms each afternoon through this weekend.

CAE WATCHES/WARNINGS/ADVISORIES

SC...None. GA...None.