textproduct: Columbia

WHAT HAS CHANGED

Morning low temperatures Saturday have trended slightly warmer. Aviation discussion updated for the 12z TAF issuance.

KEY MESSAGES

- 1. Frost/Freeze headlines could be needed this weekend, especially Sunday morning.

- 2. A front will bring mostly dry and breezy conditions today.

DISCUSSION

Key Message 1: Frost/Freeze headlines could be needed this weekend, especially Sunday morning.

A secondary front is still expected to pass tonight, ushering in a much drier and colder airmass with dewpoints falling into the 30s Friday. Persistent CAA should bring much cooler than normal temperatures Friday, through the weekend, and into early next week. High temperatures each day through Tuesday should remain in the mid to upper 50s but frost and freeze headlines could be needed this weekend. Winds are forecast to remain a bit elevated into Saturday morning, thus lows have trended slightly warmer, in the mid to upper 30s. This setup, where winds remain elevated post frontal passage, typically produces lows warmer than guidance shows. There is increasing confidence across deterministic and AI global ensembles that lows Sunday morning should dip into the low 30s, with multiple locations dropping to freezing, especially across the northern FA. The main question is how far the surface high is displaced to our northwest, but even solutions keeping it further northwest in the LREF cluster analysis still have portions of the CWA falling to freezing. Due to this, the need for frost or freeze headlines will be evaluated over the coming forecast packages. Additional nights with lows into the 30s are expected early next week.

Key Message 2: A front will bring mostly dry and breezy conditions today.

The southern stream shortwave previously discussed is moving through the region this morning supporting a broken line of showers moving across the Southeast. The initial cold front is positioned in western TN, extending toward northern MS with the deepening northern shortwave digging into the western TN Valley. These features will continue progressing eastward through the morning hours, with the front pushing through the CWA later today. Overall, there is a chance for some sprinkles this morning but measurable rainfall is unlikely.

The surface pressure gradient is expected to continue tightening through the morning and afternoon hours as the front pushes through and the surface low drifts into the Mid-Atlantic. At the same time, enhanced kinematics associated with the digging shortwave should bring a 35-40 kt LLJ that gradually weakens through the day, but should aid in mixing down gusts in the 25-30 mph range after the inversion breaks later this morning. This could yield isolated gusts reaching Lake Wind Advisory criteria across area Lakes, especially those susceptible to a westerly fetch, but have decided to hold off on the product due to the expected isolated nature. Westerly winds should gradually weaken this evening and tonight.

AVIATION /12Z THURSDAY THROUGH MONDAY/

Expecting a continuation of VFR the next 24 hours with a period of low level wind shear ending around 14Z.

Satellite imagery and surface observations indicate clear skies with a few passing high clouds. A strong low- level jet is expected to continue over the area ahead of the approaching front. The CAE VAD Profile still indicates LLWS of 35 knots at about 2kft from the west. Surface winds are from the S/SW around 4-7 kts. Once the inversion breaks around 14z Thursday, stronger winds will mix to the surface, and WLY winds will increase to 10-15 kts with gusts 20-25 kts increasingly common at all terminals. Given mixing in the boundary layer, no fog concerns tonight. The frontal boundary passage tomorrow should be mostly dry, so very low chances for precip continue. Towards the end of the period, winds shift to the NW.

EXTENDED AVIATION OUTLOOK...Dry air will likely prevent widespread restrictions through the extended. Gusty winds expected again into Friday as a cold front passes, but not as strong as Thursday.

CAE WATCHES/WARNINGS/ADVISORIES

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