textproduct: Columbia

WHAT HAS CHANGED

Updated aviation for the 12Z TAFs.

KEY MESSAGES

- 1. Near record temperatures possible by Friday before cold front moves through, bringing temperatures closer to normal this weekend. Temperatures then warm again into next week.

- 2. Fire weather concerns are expected this weekend behind the cold front, especially Saturday, with very dry air and breezy winds moving in.

DISCUSSION

KEY MESSAGE 1: Near record temperatures possible by Friday before cold front moves through, bringing temperatures closer to normal this weekend. Temperatures then warm again into next week.

500mb height rises ramp up today and Friday on the order of 2-4 dm/12hr as the upper ridge centered over the Southern Plains expands eastward. This along with warming 850 mb temperatures should yield highs that break into the low 80s this afternoon before warming further Friday. The EC EFI continues to show values above 0.90 across the area for temperatures Friday, displaying the anomalous warmth that moves in as 850 mb temperatures reach the NAEFS 99th percentile. The most recent NBM run and MOS guidance continues to indicate high temperatures that reach/exceed record values with temperatures in the upper 80s to lower 90s. The current forecast of 89F at CAE and 90F at AGS would break the record of 88F at both sites. Attention then turns to the strong cold front that is expected to move in late Friday evening into early Saturday. Not much has changed with this front as EC Ensemble and GEFS mean solutions show PWAT's reaching 150-180% of normal ahead of this with slight chance PoP's across the Pee Dee mainly late Friday. Behind this front, solid ensemble agreement remains that robust high pressure originating from Canada moves in, bringing much cooler and drier air into the FA. This surface high is expected to be near the NAEFS climatological max and temperatures over the weekend are expected to be just below normal to near normal. This surface high is expected to shift offshore early in the week with the region then becoming centered under a upper ridge. This feature should bring a familiar pattern with continued dry conditions and temperatures that warm through the end of the forecast period.

KEY MESSAGE 2: Fire weather concerns are expected this weekend behind the cold front, especially Saturday, with very dry air and breezy winds moving in.

Minimal change is seen in the outlook behind the strong cold front as very dry air is expected to surge into the region starting Friday night. There is solid model consensus that dewpoints originally in the upper 50s to lower 60s ahead of the front will crash into the low to mid 20s by Saturday afternoon with a tight surface pressure gradient as the surface high discussed in Key Message #1 moves closer. The strongest northeasterly gusts appear to move in overnight Friday, continuing into early Saturday afternoon before diminishing the remainder of the day. Forecast soundings and ensemble guidance continue to indicate gusts to 25-30 mph will be possible in the aforementioned window where an isolated gust pushing 35 mph cannot be ruled out. As dew points quickly fall, RH values Saturday afternoon should bottom out near 20%, possibly a bit lower in some spots. Due to this, confidence continues to increase in elevated fire weather concerns Saturday. The main uncertainty is how long the strongest winds will linger as there may not be a "perfect" overlap of the lowest RH values and strongest winds, but either way hazardous conditions conducive for fire spread will be in place. SPC has maintained an area highlighting the FA for critical fire weather conditions on their latest fire weather outlook for Saturday.

The main shift in guidance comes Sunday, where winds are expected to become more easterly to southeasterly, aiding in bringing slightly higher moisture to the area. Despite slightly greater moisture content and much weaker winds, minimum RH values could still near critical levels mainly in the northern FA so caution will still need to be taken for any activity that could spark a fire.

AVIATION /12Z THURSDAY THROUGH MONDAY/

VFR Conditions Expected Today....

High pressure is centered off the Northeastern US coast, with the ridge axis stretching southwest and across the forecast area this morning. After starting off mainly light and variable, winds on the back side of the surface ridge will increase while shifting to a southerly direction this morning, bringing some moisture inland. As expected, mid-level cloudiness has prevented restrictions at the terminals thus the TEMPO groups have been removed with the 12Z update. SCT to BKN decks should transition to more SCT decks as the day goes on.

EXTENDED AVIATION OUTLOOK...Mainly VFR conditions are expected into the weekend, even as a cold front moves through Friday night. This will usher in another reinforcing cool and dry air mass for the weekend. Some gusty winds are possible Saturday behind the front.

CAE WATCHES/WARNINGS/ADVISORIES

SC...None. GA...None.