982 FXUS62 KRAH 021911 AFDRAHArea Forecast Discussion National Weather Service Raleigh NC 311 PM EDT Thu Oct 2 2025
.SYNOPSIS... Canadian high pressure will build across the eastern US, then offshore, through the weekend.
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.NEAR TERM /THROUGH TONIGHT/... As of 210 PM Thursday...
A mid/upr-level ridge, and accompanying mid-level high/anticyclone centered in 12Z-observed upr air data over the OH Valley, will progress slowly ewd and across the srn Middle Atlantic tonight. Associated deep dryness, characterized by PWs of generally 0.5" to 0.8" and 50-60% of normal, will remain in place over cntl NC.
At the surface, 1033 mb Canadian high pressure centered this afternoon over the Northeast will become centered over the Middle Atlantic tonight, while continuing to ridge swwd across the Carolinas and Southeast. Initially breezy and occasionally gusty nely surface winds this afternoon over cntl NC will lessen after sunset, then probably fully decouple/calm in all but the Coastal Plain and urban Piedmont overnight.
Mainly clear and mostly calm will favor strong radiational cooling and seasonably cool low temperatures in the mid 40s to lwr 50s, supported by statistical (MOS) guidance that typically outperforms all other in such regimes.
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.SHORT TERM /FRIDAY AND FRIDAY NIGHT/... As of 310 PM Thursday...
Some degree of a Rex blocking pattern will evolve over parts of the ern US into the weekend, as a mid/upr-level trough now digging across the mid MS Valley settles across the lwr MS Valley and cntl Gulf Coast, equatorward/beneath a persistent ridge over the OH Valley and Middle Atlantic.
At the surface, the center of Canadian high pressure will migrate down the Middle Atlantic coast and maintain seasonably mild/cool nely flow over cntl NC.
While deep dryness, characterized by PWs of generally 50-70% of normal, will remain, stratocumulus moisture in nely around the ridge and beneath a couple of low-level temperature inversions, will too - supportive of scattered to areas of broken, diurnal stratocumulus. Skies should otherwise be mostly clear. With little to no change in airmass or proximity of the Canadian high, temperatures should be near to slightly above persistence ones: highs in the 70s and lows in the mid-upr 40s to lwr-mid 50s, with the latter again supported by statistical (MOS) guidance that is favored in such regimes.
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.LONG TERM /SATURDAY THROUGH THURSDAY/... As of 148 PM Thursday...
An anomalous mid-level ridge will re-amplify over eastern Canada Saturday before shifting over the northeast US Sunday into Monday. An upper trough will then move across the Great Lakes/Ohio Valley/northeast US Tuesday into Thursday.
At the sfc, high pressure will remain centered just off the Delmarva Peninsula Saturday, shifting a bit further offshore through Sunday. While flow Saturday will be weak, it will remain a bit more enely in nature. This should keep daytime highs a few degrees cooler (upper 70s to around 80) than Sunday when flow turns more esely and highs reach the lower 80s. Deeper, anomalous moisture should stay south and west of our area promoting a dry weekend. Overnight lows in the mid/upper 50s to lower 60s are expected each night.
Persistent esely flow early next week should enhance moisture flux across our area. Mid-level vorticity associated with remnants of an upper wave over the Deep South may promote scattered showers Monday and Tuesday (especially over the NC/SC border; western and southern Piedmont). Overall though, QPF should be limited early next week. Beyond Tuesday, deterministic and ensemble guidance is surprisingly in good agreement wrt to the timing of the aforementioned upper trough and the eastward progression of an associated cold front. In general, a better chance for widespread pre-frontal rain looks promising later Wednesday through mid-Thursday. It`s a bit too far to get into details, but it is worth noting that guidance currently maximizes mid/upper forcing well to our north. As such, higher QPF may trend north of us as well. Although, some instability may be possible Wednesday afternoon and evening which could enhance rain rates in isolated cells. We`ll continue to monitor as we get closer to middle of next week.
Otherwise, expect highs in the mid/upper 70s to lower 80s during this period. Ensembles/deterministic guidance is also in pretty good agreement pushing the post-frontal cooler airmass into our area by next Thursday. As such, our current forecast suggests highs in the upper 60s/lower 70s (overnight lows in the upper 40s/lower 50s) as possible on Day 8.
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.AVIATION /18Z THURSDAY THROUGH TUESDAY/... As of 145 PM Thursday...
Nely flow, around high pressure over the Middle Atlantic and beneath a couple of low-level temperature inversions, will favor periods of stratocumulus clouds based between 2500-5000 ft AGL - lowest in the morning and highest during the afternoon. The NAM and its higher- resolution Nest version indicate an associated period of MVFR ceilings will be possible from near GSB to FAY Fri morning, which seems plausible given similar, short-lived MVFR ceilings occurrence at INT earlier this morning. Additionally, there is a signal the NAM and other model guidance for areas of fog and low stratus over the nrn NC Piedmont and Southside VA Fri morning, including near and especially northeast of GSO.
Outlook: While persistent high pressure over the Middle Atlantic will favor primarily VFR conditions, associated nely to ely flow around it will favor both periods of stratocumulus based around and just above MVFR range and also a risk of patchy fog, as low-level moisture gradually increases through the weekend. The chance of showers will also gradually increase early to especially mid-next week, ahead of an approaching cold front.
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.RAH WATCHES/WARNINGS/ADVISORIES... None.
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SYNOPSIS...MWS NEAR TERM...MWS SHORT TERM...MWS LONG TERM...Luchetti AVIATION...MWS
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