FXUS62 KGSP 121034

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
634 AM EDT Mon Apr 12 2021

High pressure remains over our region through today, leading to
drier conditions. Another cold front will likely cross the area
during the middle of the week, possibly bringing more rain to the
area Wednesday. Drier and cooler air returns Thursday and continues
into the weekend.


As of 630 am: Boundary layer flow will be relatively stout from the
W/NW today across the area today, south of an elongated deep trough
extending from the Great Lakes through the Mid-Atlantic, and east of a
central Conus surface ridge. Once insolation increases later this
morning, surface winds will increase to 10 to 20 mph with occasional
higher gusts. The combination of increasing thickness values and
downslope flow will result in a notable warming over yesterday`s
max temps...generally by 5-10 degrees, with widespread 80s expected
across the Piedmont. Meanwhile, surface dewpoints will remain in the
30s into the lower 40s in most areas, yielding minimum RH in the
20-30% range. Fuel moisture is still in the process of drying out
from the weekend rainfall, but the low RH and gusty winds will
increase the fire danger this afternoon. Nevertheless, forecast
parameters don`t seem to quite align to warrant a Fire Danger
Statement for today. Relaxing winds, mostly clear skies, and low
dewpoints should allow for a fairly large diurnal temp range
tonight, but mins are still forecast to be a couple of degrees above


As of 230 AM Monday: A deep gyre of an upper low will inch east
through the Great Lakes mid-week. Accelerated deep layer west to
southwest flow will persist under this feature, possibly driving a
cold front through the region late Wednesday or more likely
Wednesday night. A leading shortwave will support increasing clouds
on Tuesday with perhaps a shower or two surviving into the mountains
late in the day. Better rain chances with perhaps embedded thunder
is a bit more likely with deeper forcing and a bit more moisture
with the front itself. Meager instability and the best shear lagging
behind the front would favor garden variety thunderstorms over
anything severe. Rainfall amounts with this progressive and moisture
starved system probably won`t amount to much, keeping the area under
the relatively dry regime that could fuel fire concerns in the
extended period. Temperatures will remain above normal through the
period despite increasing clouds followed by shower activity.


As of 235 AM Monday: Considerable uncertainty continued during the
extended, especially for this upcoming weekend. It appears that
broad but relatively flat troughing will remain atop this region
heading into this weekend with zonal flow blocking any meaningful
moist return from the Gulf of Mexico. High pressure is expected to
build in behind our mid-week system. This will support cool, dry and
mostly clear conditions. With little in the way of additional
rainfall expected with the mid-week system, fire weather concerns
may increase as downsloping breezy northwesterly flow has to
potential to support min humidity in the 20s if not lower for places
east of the mountains Thursday and possibly Friday afternoon. In
fact the latest guidance has trended stronger wind wind during this
period and may even approach our wind advisory threshold for the
northern mountains during it`s peak. The cool and dry air mass may
support frost development across sheltered mountain and northern
foothill locals. Another likely moisture starved cold front is
progged to push through the area this weekend, providing a
reinforcing shot of dry and cool continental air. In collaboration
with neighboring WFOs, trended PoPs downward over the weekend but
still maintain at least a slight chance for showers as the latest
EURO has maintained a slightly more moist and amplified system.


At KCLT and Elsewhere: VFR/mostly SKC conditions will prevail
through the period. Light SW or light/vrbl winds are expected to
increase to 10-15 kts and turn toward the west (except NW at KAVL)
later this morning and continue into the evening. Most sites should
experience gusts of around 20 kts this afternoon. Winds will likely
become light W/NW at most sites by mid/late evening, turning toward
the N/NE Tue morning while remaining light.

Outlook: VFR conds will prevail early on this week. Rain chances and
restrictions will likely return Wednesday as a cold front crosses
the area. Drier conditions redevelop for the end of the week.

Confidence Table...

            10-16Z        16-22Z        22-04Z        04-06Z
KCLT       High 100%     High 100%     High 100%     High 100%
KGSP       High 100%     High 100%     High 100%     High 100%
KAVL       High 100%     High 100%     High 100%     High 100%
KHKY       High 100%     High 100%     High 100%     High 100%
KGMU       High 100%     High 100%     High 100%     High 100%
KAND       High 100%     High 100%     High 100%     High 100%

The percentage reflects the number of guidance members agreeing
with the scheduled TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables are available at
the following link:





LONG TERM...Munroe

NWS GSP Office Area Forecast Discussion