... A cold front will cross our area from the northwest on this morning, with cool and very dry high pressure spreading over the region for Friday and Saturday. Low pressure with abundant moisture is expected to affect our region on Sunday and Monday before high pressure returns by the middle of next week.
NEAR TERM /THROUGH TONIGHT/... As of 1150 AM Thursday: Aside from minor adjustments made to temperatures/winds, no major changes were needed with this update as the near term forecast remains on track. A Red Flag Warning and Wind Advisory remain in effect for portions of the area through this evening. A Special Weather Statement remains in effect for portions of the NC Piedmont and northeast Georgia regarding the increased fire danger for this afternoon. Current temperatures are in the low to mid 70s, slightly cooler across the mountains.
Previous discussion: Heights will steadily fall as an upper shortwave crosses the region this morning and pushes a cold front across the fcst area, with dry Canadian high pressure spreading over the region in its wake. Expect low-lvl winds to turn WLY to NWLY behind the front and become quite gusty. Deep mixing today will tap into stronger winds aloft generating wind gusts likely reaching Advisory level over the higher terrain. Thus, a Wind Advisory has been issued from 10am until 8pm today for the Northern Mtns including Madison and Buncombe Counties. The deep mixing will also lead to significant drying during the day with RH values likely approaching fire danger criteria over much of the fcst area. Highs will be near normal across the mountains and up to 10 degrees above normal over the lower terrain. The considerably cooler air won't advect into the area until later tonight and tomorrow.
SHORT TERM /FRIDAY THROUGH SATURDAY/... As of 111 am Thursday: All of our weather concerns are of the non-precipitating variety for the end of the week. We should be under a cool and dry NW flow aloft that supports a large continental sfc high building in Friday and moving past on Saturday. Actually, it will be very dry on Friday, with afternoon RH making it down at least into the low 20 pct range, and probably down into the teens. Some residual winds aloft should be able to mix down into the early afternoon, meaning that we will probably have Fire Weather concerns thru the afternoon, possibly Red Flag conditions in some locations. Temps will be well below normal under a sunny bright sky. The sfc high should be located overhead at daybreak Saturday, providing for excellent radiational cooling conditions that will allow for temps to fall down into the mid/upper 30s across the area east of the mtns, with freezing temps over the higher terrain. This raises the strong possibility of frost across at least the NC foothills and NW Piedmont, but right now the fcst keeps temps above 32F outside the mtns. We will continue to monitor this situation as well. We should see some rebound in temps on Saturday as the high moves off to the east, while high clouds begin to stream in from the SW ahead of the next weather system in the afternoon.
LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... As of 1224 AM Thursday: The hits just keep on coming through the first part of the medium range. The model guidance has not substantially changed with the overall plan that would have a srn stream system getting picked up and kicked out to the northeast on Saturday night/Sunday/Sunday night, with the same timing differences noted in previous model cycles. The important details remain murky. Either way, still a good bet that moisture return will be well underway Saturday evening with precip spreading up from the southwest in the pre-dawn hours. Once the moisture comes in, it should do so with a vengeance as the Gulf will be wide open. The GFS suggests PW climbing above 1.5 inches which is well above the top end of the sounding climatology, so needless to say this system looks wet. Both models suggest a heavy rain threat on Sunday/Sunday night as all manner of strong forcing and deep moisture is brought to bear, with the potential for a few inches widespread across the region. Fortunately, it has been fairly dry in the last week or two so perhaps some of this can be tolerated. The chance of severe thunderstorms looks to be on an increasing trend, which is also worrisome, with the guidance now suggesting the passage of a triple-point sfc low over the srn Appalachians during peak heating on Sunday in the case of the GFS. If that were to happen, it would be less likely that any weak wedge or cool pool would be able to hold on, which could expose the area east of the mtns to at least a high shear/low CAPE environment if not more. We will continue to monitor this potential over the next day or two. This system should exit quickly late Sunday night/Monday morning, so precip chances diminish then. We might get one above normal day before the long-wave upper trof to our west allows for a cooler high pressure air mass to start building in to bring us back down below normal. Confidence is really stretched thin beyond that, with a weak system sheared out and caught up in the fast cyclonic flow that would come through Tuesday or Wednesday. Looks like less of a chance of high elevation snow in this cycle. Thursday should be dry again with temps slightly below normal.