... High pressure sticks around into early Saturday leading to dry conditions. Hot temps can be expected outside the mountains today and tomorrow. Potential Tropical Cyclone Three will track north out of the Gulf of Mexico this weekend increasing shower and thunderstorm chances. As Potential Tropical Cyclone Three tracks northeast across the southeastern United States, shower and thunderstorm chances continue into Monday. Tuesday a cold front tracks in from the west keeping shower and thunderstorm chances around.
NEAR TERM /THROUGH SATURDAY/... As of 950 PM: Not seeing the need for much change in the overnight fcst grids. High pressure continues to be the main player overnight and winds will become weak within steep sfc-based inversions. A decaying MCS across the middle Ohio Valley will be moving into increasingly stable air as it approaches the Appalachians over the next few hrs, and it is presently not expected to reach the CWA. Thin cirrus bands surrounding Potential Tropical Cyclone Three will advance into the area tonight; there remains time for the storm to be classified as a TC before making landfall later tonight and then moving ashore. This afternoon we initiated the first steps of tropical cyclone ops, although the notable threat at this time remains mainly hydrologic, along with a small risk of TC tornadoes.
Despite the thin cirrus seen overnight, after two briefly foggy mornings in the Little TN Valley, think it is reasonable to expect some fog there given the moisture return and still decent radiational cooling. Outer bands of rain will begin to impinge upon the FA Sat afternoon with the best chance of -shra/tstm activity occurring across the mtns due to enhanced mechanical lift. Chances look a bit better than previously forecast, in light of the expected lapse rates aloft and better confidence that LCLs/CCLs will be low enough for initiation. Revised PoPs are generally 5-10% higher. Mixing will remain good Sat and low-level gusts will once again develop during the afternoon. Max temps will be a little tricky as more widespread cloudiness is possible west, but for now have highs right arnd normal levels across the area.
SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... As of 2:00 PM Friday: A potential tropical low will be tracking northeastward across the Deep South Saturday night. This low will track out of the Deep South into NE GA and the Carolinas Sunday. This low will lead to an influx of tropical moisture across the CWA Saturday night into Sunday leading to increased cloud cover as well as shower and thunderstorm chances increasing from the SW to the NE. In response, high temps will be several degrees below normal Sunday. Global models are coming into better agreement and are all now showing a northeastward track across the Deep South and the Carolinas during the short term period. However, models are still not in agreement in regards to the exact timing, strength, and track of this system.The 12z NAM and ECMWF agree with keeping a closed low level center as the low tracks across the region. The NAM is the most northern solution of the models and has the low tracking right over our FA. The ECMWF, Canadian, and GFS still show the center of the low just to our southeast. The 12z GFS continues trending weaker having the low open up into a trough. The amount of QPF that falls across the CWA will rely heavily on the intensity and track of this low. Currently the GFS, ECMWF, and Canadian have a very limited QPF response across the NC mtns. The Canadian and ECMWF have the higher QPF response confined to the SC Upstate and portions of the NC Piedmont. Since the NAM takes the low directly over the CWA, this would give the entire area CWA a good chance to see some QPF from this system. Despite better model agreement compared to the last few days, forecast confidence remains low on the track and intensity of this low, leading to low forecast confidence in the potential rainfall totals. The WPC currently has nearly the entire CWA in a slight risk for excessive rainfall on Sunday. The SPC has the portions of our far SE counties in a marginal risk on Sunday. Therefore, isolated severe wx along with hydro issues are impacts we could see from this low. Make sure to stay updated with the latest forecast information regarding this low in the coming days. Sunday night into early Monday morning this low should track NE out of our FA. Highs Monday will be a couple of degrees above normal. A cold front will approach from the west towards the end of the period increasing shower and thunderstorm chances again, especially for the mountains.
LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... As of 2:30 PM Friday: A cold front will approach from the west at the start of the forecast period leading to increased shower and thunderstorm coverage early next week. Meanwhile a high pressure system will track east across the southern United States throughout the extended period. The cold front should be just west of the mtns Tuesday morning with high pressure building in behind it. The timing of this cold front varies across the global models. The GFS currently has the FROPA tracking into the CWA Tuesday morning and exiting early Wednesday. The Canadian shows a similar solution, however it is slightly slower. The ECMWF has the front tracking into the FA Tuesday morning and stalling across the SE FA early Wednesday before tracking out late Wednesday afternoon. Depending on what time the front pushes through, severe wx could be possible, especially during peak daytime heating. The ECMWF, GFS, and Canadian show decent shear values from 25 to 35 knots around 18z. GFS soundings show SBCAPE values ranging from 500 to 1,000 J/kg across portions of the NC Piedmont and SC Upstate. This front should track east while high pressure builds in Wednesday night Thursday. Wednesday night into early Thursday morning should remain dry, therefore have no mention of PoPs during this time. Thursday into Friday a slight chance to chance for PoPs enters back into the forecast as high pressure is expected to track off the NE CONUS while a shortwave approaches the CWA. High temps through the extended period should remain a few degrees below climo.