... Dry and warm high pressure remains over our area today. Low pressure moves east from the Gulf across Florida on Tuesday as a weak cold front crosses our area. Dry and colder Canadian high pressure settles across the region Wednesday through Friday. A low pressure system moves up the Atlantic coast Saturday as a cold front crosses the area from the northwest.
NEAR TERM /THROUGH TONIGHT/... 900 AM Update...Fcst remains in good shape. Mountain wave Ci has scattered out to an extent as upstream moisture dwindles, but widely scattered Ci still in place. No major changes this update cycle.
A split flow pattern begins the period as a srn stream s/w crosses the Deep South and combines with a deepening mlvl trof from the north. This srn wave will attenuate thru the period and instigate weak cyclogenesis across the nw/rn GOM overnight, however, the main sensible weather impact for the FA will be increasing mid/upper clouds from the southwest during the latter part of the period. The NAM is more aggressive with moistening the column than the GFS, yet still expect decent opaque cloudiness to hold min temps on the higher side of guidance, esp across the srn half of the FA. The mlvl flow remains generally w/ly during the period, which will maintain a lee trof and sw/ly winds outside the mtns during the day. Not a great gust potential day as the BL flow remains on the weak side, yet occasional low-end gusts are possible across the Upstate and the mtn valleys. Colder than normal temps will begin the day...but modest insol combined with sw/ly sfc flow will enable temps to reach normal levels across all areas.
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... As of 130 AM EST Monday: Northern and southern streams remain out of phase on Tuesday with a Gulf low well to our south and a Great Lakes low well to our north. A weak cold front trailing the northern wave crosses the area Tuesday with some weak northwest flow and shallow upslope moisture in its wake. There will still be enough moisture and mechanical lift form isolated light, elevation dependent rain/snow showers along the TN border. No significant accumulation is expected. Cold high pressure builds in for Wednesday. Highs Tuesday look to be near normal across the mountains and up to 5 degrees above normal elsewhere. Lows Tuesday night around 5 degrees below normal for the mountains and near normal elsewhere. Highs cool to 5 to 10 degrees below normal Wednesday with lows around 10 degrees below normal Wednesday night.
LONG TERM /THURSDAY THROUGH SUNDAY/... As of 250 AM EST Monday: Agreement in the overall forecast pattern but detail differences remain lending to a low confidence forecast. Short wave energy digs a deep trough over the eastern CONUS Friday which moves east Saturday with nearly zonal flow by Sunday. The operational runs of the models favor High pressure over the area Thursday eroding as cyclogenesis takes place off the Carolina coast Friday. The low moves up the coast Friday night as a cold front crosses the area. Cold high pressure builds in on Saturday which moves east on Sunday. These runs show the low forming closer to the coast with some moisture pulled back westward, but the bulk of the moisture would come in ahead of the front with some lingering NW flow moisture across the mountains. The GFS and ECMWF are very similar with mainly light rain outside of the mountains with elevation dependent rain/snow across the mountains leading to accums of a couple of inches across the higher elevations. The Canadian is very similar with its pattern but the low is even closer to the coast with more precip and colder temps across our area. The GFS ensemble mean is on the wetter and colder side, but the individual members are all over the place with a very wide spread in solutions keeping uncertainty high and confidence low. The model blend forecast is similar to the operational GFS and ECMWF, so the forecast trends strongly that direction. Obviously, everyone will need to keep abreast of the latest forecasts as things can and will likely change as the event nears. Temps look to be below normal through most of the period, but rising to near normal Sunday.