The week at a glance
This should be a fairly quiet week across Central Appalachia.
Clouds left behind by the departing coastal storm may linger Monday, particularly across western Pennsylvania and the mountains. Patchy valley fog is also possible during the first few mornings of the week.
Tuesday through Thursday should be dry and increasingly warm. Thursday looks like the warmest day, with highs near 80 around Pittsburgh and well into the 80s in parts of West Virginia and western Maryland. Humidity will remain low enough to prevent a significant heat hazard.
A front may bring scattered showers beginning Thursday night or Friday. Rain chances could linger into the weekend, but forecast confidence drops considerably after Thursday. At this point, neither severe weather nor heavy rainfall appears likely.
Full technical briefing
Seven-day forecast for Central Appalachia
This outlook covers western Pennsylvania, eastern Ohio, northern West Virginia, western Maryland and nearby portions of Central Appalachia.
| Day | Expected pattern | Main concern | What CAWA should do |
|---|---|---|---|
| Monday, Sept. 28 | Mostly dry with lingering clouds | Early fog and low ceilings; isolated ridge drizzle | Check valley visibility before the morning update |
| Tuesday, Sept. 29 | Dry and seasonable | Patchy morning valley fog | Routine monitoring is enough |
| Wednesday, Sept. 30 | Sunny and warmer | No significant hazard expected | Routine monitoring is enough |
| Thursday, Oct. 1 | Warmest day of the week | Unseasonable warmth; showers possible late | Watch the front’s timing Thursday evening |
| Friday, Oct. 2 | Scattered showers possible | Wet roads; low-confidence storm chance | Keep coverage flexible rather than planning a full operation |
| Saturday, Oct. 3 | Front may remain nearby | Scattered showers; cooler temperatures | Check whether rain is clearing from northwest to southeast |
| Sunday, Oct. 4 | Uncertain frontal position | Additional showers possible | Reassess after the late-week system becomes better sampled |
Monday: Clouds and pockets of fog
The coastal storm responsible for the weekend’s clouds and wind will continue pulling away. Most of the region should remain dry, although a little drizzle or an upslope shower could linger along the Laurel Highlands and the higher terrain of northern West Virginia and western Maryland.
Low clouds may be stubborn around western Pennsylvania. NWS Pittsburgh indicates a 40–60% chance that IFR ceilings linger into Monday morning at several aviation locations. Patchy valley fog is also possible, especially where skies clear and winds become light.
No land-based watches, warnings or advisories were in effect for the Pittsburgh, Cleveland or Charleston forecast areas Sunday afternoon.
Check webcams and visibility observations in the river valleys before posting the morning forecast. Conditions should gradually improve during the day. NWS Pittsburgh forecast discussion forecast.weather.gov
Tuesday: Quiet and seasonable
High pressure takes control Tuesday. Afternoon temperatures should generally reach the lower and middle 70s across eastern Ohio and western Pennsylvania, with somewhat warmer readings farther south.
Fog may redevelop before sunrise in the sheltered valleys of West Virginia and western Pennsylvania. NWS Charleston expects any dense valley fog to lift quickly after sunrise.
Routine monitoring is enough once the morning fog clears. NWS Charleston forecast discussion forecast.weather.gov
Wednesday: Warmer, with plenty of dry weather
Upper-level ridging will build across the eastern United States, allowing temperatures to climb. Most lower elevations should reach the middle or upper 70s, with lower 80s possible in parts of West Virginia.
Dry air and weak forcing should prevent meaningful shower development. No organized hazardous weather is evident.
Routine monitoring is enough. If fog forms early, it should be confined mainly to the usual sheltered valleys.
Sources: NWS Cleveland forecast discussion, NWS Baltimore/Washington forecast discussion forecast.weather.gov
Thursday: Warmest day of the week
Thursday should be the warmest day across most of the coverage area. NWS Pittsburgh places the probability of reaching at least 80 degrees between 50% and 80% across most lower elevations south of Interstate 80. Western Maryland may reach the middle 80s, while parts of the West Virginia lowlands could also climb well into the 80s.
This is unseasonably warm, but it does not currently qualify as a meaningful heat hazard. Dew points are expected to remain near or below the lower 60s, and NWS Pittsburgh places the chance of moderate-or-greater heat impacts at 10% or less.
A front approaching from the west may bring showers into eastern Ohio late Thursday or Thursday night. Timing remains uncertain, with recent guidance trending slower.
Watch the front’s progress Thursday evening. There is no reason yet to prepare heat alerts or active storm coverage. NWS Pittsburgh forecast discussion forecast.weather.gov
Friday: Scattered showers, but limited hazards
The front should bring scattered showers into more of the region Friday. Rainfall is expected to remain modest: NWS Pittsburgh places the chance of exceeding half an inch during any 24-hour period below 40%.
Severe-weather potential also appears muted because instability should be weak. A rumble of thunder cannot be ruled out, but current official local guidance does not identify an organized damaging-wind, hail or tornado threat.
Confidence is moderate that some rain occurs, but low on its exact timing and coverage. Keep coverage flexible and avoid presenting Friday as a washout this far in advance.
Saturday and Sunday: Forecast confidence drops
The weekend depends on how quickly the front moves through the Appalachians. Scattered showers may linger, especially over West Virginia and western Maryland, while eastern Ohio and western Pennsylvania could begin drying sooner.
NWS Charleston notes substantial model-to-model and run-to-run differences after Thursday. NWS Baltimore/Washington likewise says temperatures and rain chances hinge on how far south the front advances.
No official severe-weather or excessive-rainfall signal is identified at this range. Check Saturday morning whether conditions are clearing from northwest to southeast, then reassess Sunday rather than carrying an outdated broad rain message through the entire weekend. forecast.weather.gov
Operational meteorology and communication updates
WPC’s Probabilistic Precipitation Portal becomes operational this week
Status: Operational transition scheduled around October 1
WPC’s Probabilistic Precipitation Portal is scheduled to transition from experimental to operational status around October 1. The portal displays the probability of exceeding selectable precipitation amounts during the next 72 hours, along with ranges of plausible totals.
For CAWA, its best use is helping explain uncertainty when deterministic rainfall maps disagree or when narrow heavy-rain corridors are possible. It may be especially useful for deciding whether public messaging should emphasize a likely general rainfall or a lower-probability, higher-impact outcome.
If CAWA uses its graphics publicly, always include:
- The rainfall threshold being shown
- The probability of exceeding that threshold
- The valid period
- A reminder that the probability is not a predicted coverage percentage
Bookmark and begin testing the NWS Probabilistic Precipitation Portal. wpc.ncep.noaa.gov
RRFS and REFS implementation is one week away
Status: Scheduled implementation October 6
NCEP remains scheduled to implement RRFS and REFS on October 6. Operational production of NAM, NAM Nest, SREF, HREF, HiresW and NAM MOS is expected to end with that transition.
This is now an immediate data-continuity issue. Any CAWA dashboard, spreadsheet, downloader or forecasting workflow using the retiring datasets should have a tested replacement before next week’s briefing.
The field names and statistical construction of REFS products are not necessarily identical to similarly named HREF fields. Avoid swapping URLs while assuming the resulting probabilities mean exactly the same thing.
Source: NWS RRFS and REFS implementation notice
CAP comment period has closed
Status: Proposal remains under consideration
The initial NWS comment period concerning a possible transition from VTEC-centered alert dissemination to Common Alerting Protocol messages closed September 21.
No final implementation decision or transition schedule is identified at this time. CAWA should continue supporting its current alert workflow while documenting any dependence on raw VTEC strings.
Do not remove VTEC processing based solely on the proposal. Wait for a formal NWS decision, technical documentation and implementation schedule.
Source: NWS CAP transition information weather.gov
No other consequential national change identified
No additional NWS, SPC, WPC, NCEP, MRMS or AWIPS change with a clear operational impact on CAWA was identified since the previous briefing.
The primary work items remain the October 1 precipitation-portal transition and the much larger October 6 RRFS/REFS implementation and legacy-model retirement.
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