textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

Updated for a new Aviation Discussion.

KEY MESSAGES

1. Near-critical fire weather conditions are expected this afternoon away from the TN border, making outdoor burning dangerous. 2. Temperatures warm throughout the week and into the weekend, with a cold front increasing rain and possible thunderstorm chances across the area early Thursday into Friday.

DISCUSSION

Key message 1: Near-critical fire weather conditions are expected this afternoon away from the TN border, making outdoor burning dangerous.

Now that the NW flow snow machine has tapered off to flurries at daybreak, our attention turns to the fire weather situation this afternoon as near-critical low RH spreads through most of the CWA. Northeast Georgia counties dip into the 15-20% range with slightly higher RH ranges of 20-25% elsewhere. Given the snowfall at the NC/TN border, this should help decrease the fire risks, but outside of that location, fuels remain dry. Winds are slow to veer southwesterly by this afternoon. Gusts of 10 to 15 mph are expected. The best overlap of wind and low RH is expected over northeast GA, so a Fire Danger Statement was issued in those zones for the afternoon. Further coordination with land management agencies could result in an expansion of the Increased Fire Danger SPS.

Winds begin to steadily increase from the southwest tonight, slowly increasing moisture into the region. Gusts of 20 to 30 mph are possible across much of the area during Wednesday afternoon. Humidity is expected to increase during this time, increasing RH into the 30-45% range. Fuel moisture should remain low and temperatures increase, so fire danger is expected to remain a bit elevated into mid-week.

Key message 2: Temperatures warm throughout the week and into the weekend, with a cold front increasing rain and possible thunderstorm chances across the area early Thursday into Friday.

Guidance continues to signal for a short wave trough swinging through the area by the end of the week, increasing shower and possibly thunderstorm chances. By Thursday, guidance has diverged from previous runs and has showers and potential thunderstorms developing along a baroclinic zone over the CWA. The previous runs showed a stronger surface low and the latest data from both the EURO and GFS weaken the low and FROPA. Prefrontal showers look to start early on Thursday before the front swings through Thursday night and into Friday morning, but this could change. As of the current trends, the likelihood of this system bringing at least 1" of rainfall remains in the 60-70% range, mainly for the far western NC mountains. As far as thunderstorm potential, one limiting factor at this point is timing of the front moving through overnight. However, with showers developing throughout the daytime, there is a 30-40% chance of at least 100 J/kg of sbCAPE during peak heating time primarily across the northeast GA locations. Overnight, instability remains very low to nonexistent. Looking at model soundings only keeps the confidence very low for severe thunderstorm chances. Analysis shows almost a unidirectional westerly wind profile, little to no instability and very weak surface/midlevel lapse rates. Cannot rule out a rumble of thunder or higher convective rain rates, but this will continue to be monitored.

As for temperatures, the warming trend continues from Tuesday onward. Surface winds return to more of a southerly flow, advecting plenty of moisture back into the southeast ahead of the front. Above, gradual height rises contribute to the warming temps. Expect 60s for most of the week and into the 70s for the weekend.

AVIATION /12Z TUESDAY THROUGH SATURDAY/

At KCLT and elsewhere: Still dealing with a plume of MVFR-level stratocu blowing up the French Broad Valley to KAVL at this hour, but satellite imagery continues to show the low clouds shrinking as the NW flow weakens. Should become VFR by mid-morning, but with extensive high level clouds as orographic cirrus has developed downwind of the mtns. Otherwise, VFR at all terminals through the period. Wind has diminished quite a bit since midnight, and will be light/var in some spots, before a switch to SW around midday as the sfc high center moves past to our south. Wind will become gusty again late this evening as the pressure gradient increases ahead of the next system.

Outlook: Quiet weather returns to the region thru Wednesday. Another low pressure system will approach the area on Thursday, bringing showers and associated restrictions.

GSP WATCHES/WARNINGS/ADVISORIES

GA...INCREASED FIRE DANGER from noon EST today through this evening for GAZ010-017-018-026-028-029. NC...None. SC...None.