246 FXUS62 KRAH 221929 AFDRAHArea Forecast Discussion National Weather Service Raleigh NC 329 PM EDT Mon Sep 22 2025
.SYNOPSIS... High pressure will continue to extend across the Middle Atlantic today, then weaken and merge with a larger high near Bermuda through mid-week.
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.NEAR TERM /THROUGH TONIGHT/... As of 325 PM Monday...
Dry tranquil weather will prevail across central NC through tonight. 500 mb analysis depicts a shortwave off the GA/SC coast which is resulting in some convection that is largely offshore. This disturbance will move NE, spreading some scattered to broken mid and high clouds into central NC this afternoon through tonight, especially in the east. Given ample stability and dry air in the low levels and a surface ridge extending SW down the northern Mid- Atlantic coast into the eastern Carolinas, no precipitation is expected. Dew points have mixed out into the 50s at many spots this afternoon with all the dry air just above the surface, and the latest forecast reflects this trend and relies heavily on high-res guidance for dew points. The ridge axis shifting eastward has turned the low-level flow to a more E/SE direction instead of NE, helping high temperatures reach near or a degree or two higher than yesterday, mostly lower-to-mid-80s (maybe upper-80s near the SC border).
Forecast soundings and winds going very light to calm from a relaxed surface pressure gradient indicate patchy fog is possible again tonight, locally dense, mainly over the Sandhills and Coastal Plain near the surface ridge axis. However, the presence of mid and high clouds there could be a limiting factor, especially if they hang around longer than expected, as guidance has clouds thinning out overnight. Furthermore, based on the relatively isolated nature of fog the last few mornings, and backing off of low visibilities on the latest HRRR runs, confidence in widespread dense fog is low. Forecast lows are again in the upper-50s to lower-60s.
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.SHORT TERM /TUESDAY AND TUESDAY NIGHT/... As of 1240 PM Monday...
A short wave trough passing across the Ohio Valley may extend far enough south, that when coupled with afternoon instability and localized lift via the Piedmont trough... could result in a few stray showers/tstms across our NW Triad zones Tuesday afternoon and evening. Elsewhere and farther east across central NC, fair weather is expected due to the lingering ridge and slightly drier airmass. Temps will continue to run above average for this time of year, and perhaps a couple deg warmer than today. Highs in the mid 80s north and northwest to around 90 south and southeast. Lows Tuesday night in the 60s.
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.LONG TERM /WEDNESDAY THROUGH MONDAY/... As of 100 PM Monday...
An upper level low will be over the Great Lakes Wednesday morning with an associated surface low across the Central Plains. Can`t rule out a couple of showers Wednesday or Wednesday night across the northern half of the forecast area, but the more likely chance for rain will begin Thursday afternoon along and west of US-1. Rain is likely across all locations Thursday night and Friday. There`s a bit of model disagreement as to how quickly rain will move out - the 00Z ECMWF dries things out pretty quickly Friday night, while the 12Z GFS keeps a chance of showers through the weekend. The official forecast keeps a 40-50% chance of showers Friday night, a 30-40% chance of showers Saturday, then a 20% chance of showers Saturday night and Sunday.
Hazards: Considering the slow movement of the system, there is a marginal risk (level 1 of 4) of flash flooding Thursday along and west of US-1, then across all locations on Friday. Despite the dry conditions recently, the storm motion will likely be along the front itself, meaning that storms could repeatedly move across the same area. In addition, while there is a slight chance of thunderstorms on Thursday and Saturday, the most likely day for thunderstorms will be Friday as that will be the day with the greatest instability. Considering the strength of the accompanying upper level system, Friday could have some strong to severe thunderstorms, although the Storm Prediction Center currently does not include any locations in their outlooks past Wednesday.
Temperatures: Wednesday should be the warmest day out of the next seven, with highs ranging from the mid 80s to the low 90s. Highs will drop a few degrees each day with additional cloud cover and chances for rain, with highs on Saturday/Sunday around 80 and in the 70s on Monday. Lows will mostly be in the 60s, with some upper 50s across the north Saturday and Sunday nights.
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.AVIATION /18Z MONDAY THROUGH SATURDAY/... As of 150 PM Monday...
24-hour TAF period: Unlike yesterday, skies cleared quickly this morning across central NC, with VFR prevailing at all sites. VFR and dry weather will continue everywhere through this evening. An upper disturbance will bring a shield of mid and high clouds to central NC, especially east, from this afternoon through tonight. There may also be some redevelopment of patchy shallow fog and very low stratus late tonight and early tomorrow morning, mainly in the east (including RWI and FAY). With the 12z HRRR and HREF probabilities slightly backing off on fog compared to previous runs, the lack of its widespread development the last few mornings, and the possibility of some mid and high clouds lingering overnight in the east, confidence in widespread dense fog occurring tonight is low. So went with TEMPO groups for fog instead of prevailing lines at RWI and FAY, and expect any would quickly dissipate after sunrise. Winds will veer from E/NE now to SW by tomorrow morning, remaining light (7 kts or less).
Outlook: Areas of stratus and fog will be possible again Wed and Thu mornings, mainly at and east of RWI and FAY. Showers/storms are expected to reach INT/GSO with isolated coverage late Tue afternoon- evening and with scattered coverage Wed afternoon-night. Their probability of occurrence will increase and overspread the west on Thu and all of cntl NC Thu night and Fri, with associated flight restrictions. Scattered showers may linger into the upcoming weekend, as a slow-moving trough aloft and surface cold front approach our region.
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.RAH WATCHES/WARNINGS/ADVISORIES... None.
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SYNOPSIS...MWS NEAR TERM...Danco SHORT TERM...np LONG TERM...Green AVIATION...Danco/MWS
NWS RAH Office Area Forecast Discussion