Area Forecast Discussion
Issued by NWS Greer, SC
Issued by NWS Greer, SC
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709 FXUS62 KGSP 200547 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 147 AM EDT Thu Jun 20 2024 .SYNOPSIS... High pressure atop the region will suppress any storms from developing this week until moisture returns on Saturday. A heat wave gets underway on Friday and remains hot through the start of next week. A weak cold front approaches from the north early next week but is expected to stall out then dissipate. && .NEAR TERM /THROUGH TODAY/... As of 1:35 AM Thursday: An elongated stripe of thick cirrus continues to linger over our western zones, with more sct cirrus extending well east of the main stripe. These clouds will likely slow radiational cooling somewhat over the next few hrs, but they should sct out as the overnight/morning wears on. They could also limit the amount of patchy fog that develops over the mtn valleys. We shall see. Otherwise, the upper anticyclone and attendant ridge will remain west-through-north of the forecast area, with deep easterly flow expected through much of the period. The low level flow is expected to weaken tomorrow, as surface high sags south and weakens across the western Atlantic...and a weak easterly wave approaches the Southeast Coast. This should result in a slight warm-up of 1-2 degrees on Thursday afternoon. Min temps will otherwise again fall to near-normal levels thanks to the relatively dry airmass. Said air mass will continue to limit diurnal instability to meager- at-most levels, with little-to-no chance of afternoon/evening convection through the period. && .SHORT TERM /TONIGHT THROUGH SATURDAY/... As of 142 PM EDT Wednesday: The week should end with typical summer heat that starts to build into the weekend. A breakdown of sorts in the large eastern upper anticyclone should be complete by Friday, with one center migrating to the TN Valley region and other offshore, separated by a weakness brought on by a weak easterly wave that runs into the Southeast Coast. Although this might suggest some increase in precip potential, especially Saturday, the model guidance keeps that potential near the coast, in part because of how strong the cap remains in place across our region through Saturday, even over the higher terrain. The upshot is that we stay relatively dry as sfc high pressure lingers over the region. That makes the high temps the main concern, although merely normal on Friday, but then creeping up a few degrees above normal into the middle 90s in places east of the mtns. Be that as it may, the humidity will not be high enough to raise the heat index more than a deg or two above the air temp, so no big problems yet. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... As of 222 PM EDT Wednesday: The second half of the weekend looks like a quick transition aloft as the old upper anticyclone to our west breaks down further and the center retrogrades to the Southwest on Sunday, while in its place a cyclonic flow aloft is introduced by a northern stream system moving across the Great Lakes to eastern Canada/New England through Monday. At a minimum, the pattern shift favors a return to at least climo precip probs starting on Monday, but the mid-upper troffiness lingers into the middle of the week, suggesting less of a diurnal dependence to the convection and more potential for a shower/storm at any time of the day. The expectation is for the region to finally get into a more pulse-severe type regime. A thermal ridge will remain, allowing temps to climb about five degrees above normal each day, while an increase in the humidity will finally allow the heat index to climb upwards toward more uncomfortable values, but perhaps not yet into Heat Advisory range. Because this should be our first real hot weather of the season, it still warrants a mention in the HWO east of the mountains. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... At KCLT and elsewhere: Expect VFR conditions to continue thru the 06z taf period across our area. Some patchy mtn valley fog may form again overnight and into the morning, but it`s not expected to affect KAVL, however it cannot be entirely ruled out. Otherwise, I expect little change in the synoptic pattern for Thursday with dry high pressure in control. The shield of bkn cirrus currently over our area will gradually sct thru the morning with another round of sct VFR clouds expected this afternoon and evening. Winds will remain light to calm at most sites thru the morning and then pick up from the ENE outside of the mtns for the aftn/evening. At KAVL, winds will pick up from the SE this aftn/evening. Outlook: An expansive upper ridge will keep things mostly dry with VFR conditions thru Friday. Mtn valley fog and/or low stratus will be possible each morning. Isolated diurnal convection will be possible over the mtns on Saturday, with a return to more sct convection across the region Sunday and Monday. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...DEO NEAR TERM...ARK/JPT SHORT TERM...PM LONG TERM...PM AVIATION...JPT