... High pressure through early Thursday night. Next system approaches Friday.
NEAR TERM /THROUGH TONIGHT/... As of 135 AM Wednesday...
Quieter weather in the near term in between systems with surface high pressure the overall dominant player for the middle Ohio Valley and central Appalachians. Weak cold front drops in from the northwest, but will not amount to much other than a barely noticeable pressure minimum and scattered to broken mid level clouds 18Z-00Z Thursday. Will also see a reinforcement of the thermal trough at 850mb, quickly followed by warm air advection off the surface through 12Z Thursday. Flow aloft turns zonal. A challenge to the forecast will be whether or not to keep/increase clouds during the passage of the thermal trough with the aforementioned front over the northeastern zones.
SHORT TERM /THURSDAY THROUGH FRIDAY/... As of 943 PM Tuesday...
Reduced threat of freezing rain and sleet for Thursday night and Friday morning for the eastern and northern CWA. Guidance indicates the threat should be briefer in duration than what was previously expected.
As of 246 PM Tuesday...
Surface high pressure will drift across the region Wednesday night and shift quickly towards the northeast US by late Thursday. This feature will promote dry conditions across the area Thursday with highs in the mid/low 40s, just a few degrees below normal for this time of the year.
Cloud cover will be on the increase Thursday night ahead of mid level shortwave energy that will move across the southern US. This will lead to cyclogenesis in the northern Gulf Coast region, and eventually a coastal low will lift northward along the southeast coast on Friday. This will contribute to precipitation chances increasing across our area from south to north throughout the day. As precipitation initially arrives Friday morning, the aforementioned surface high in the northeast US will wedge down along the eastern slopes of the mountains, providing a shallow layer of sub-freezing air at the surface as WAA increases aloft. Thus, thermal profiles could be favorable for a period of freezing rain Friday morning, particularly across southeastern areas of the CWA. In addition, snow/sleet is possible at the onset of precipitation in the mountains Friday morning. However, by Friday afternoon, low-level cold air will scour out and precipitation will transition to rain across the region.
LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... As of 246 PM Tuesday...
By Friday night, the aforementioned coastal system will pass east of the area and continue to move towards southern New England by Saturday afternoon, strengthening as it does so. Due to a combination of additional shortwave energy moving across the Great Lakes and moisture wrapping around the coastal system, additional precipitation will continue into Saturday with rain expected area-wide during the day. Precipitation is then expected to transition to snow Saturday night into Sunday as surface temperatures cool. As the coastal system continues to lift to the NNE into eastern Canada, the flow aloft across our area becomes more favorable for a period of upslope precipitation Sunday afternoon. Drier air is then expected to bring an end to any upslope precipitation by Sunday evening.
Any break in precipitation activity across the area is expected to be short-lived as models indicate that a low pressure system will develop near the lower Mississippi Valley on Monday. This system is expected to bring another round of rain and/or snow across the area Monday into Tuesday, but models disagree on the track/timing of the system for now. Thus, have stuck with central guidance on PoPs for now until better model agreement occurs.