... High pressure over the Great Lakes builds eastward through Tuesday. Low pressure passing north of the Great Lakes will aim to lift a warm front through the area during the middle portion of the week. A cold front will approach the region thereafter before stalling in the region as we head into next weekend.
NEAR TERM /THROUGH TONIGHT/... High pressure has migrated over the lower Great Lakes region this afternoon as a cold front sits off the Southeast coast. Locally, a mix of clouds and sun overspreads the CWA as a cold air advection regime as allowed for fair weather cumulus clouds to developed area wide. With a northerly breeze gusting 15 to 20 mph at times, temperatures are hovering in the low to middle 70s with dewpoints quite comfortable in the 40s.
Dry and mostly clear conditions expected to persist overnight as the aforementioned high continues to build eastward into the region. Northerly winds will slacken by this evening, remaining light overnight, as clear and seasonably chilly conditions prevail. Lows by daybreak will drop into the 40s for much of the area, with lower 50s holding on in the cities, while upper 30s will be possible in the higher elevations of the Allegheny Mountains.
SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... The high moves atop the Mid-Atlantic on Monday with continued dry conditions and temperatures still running several degrees below normal in the low to middle 70s. Plenty of sunshine can be expected as light winds trend out of the west northwest. Clouds increase Monday night as we start to warm advect aloft and a weakening shortwave drops southeastward from the Great Lakes. Have low end chance POPs across the Potomac Highlands late Monday night, with a dry forecast elsewhere. Lows Monday night generally in the 50s.
By Tuesday, the surface high shifts off the coast, turning winds more southerly and allowing for an increase in temperatures and moisture. As temperatures rise to near normal levels for early June, dewpoints will tick upwards through the 50s, nearing 60 degrees across central Virginia. While we will be lacking any strong lifting mechanism, a warm front will be approaching to our west southwest. We will continue to advertise a chance of an afternoon shower or storm, mainly along and north of the Potomac River. Surface low pressure and associated shortwave drops southeastward once again from the eastern Great Lakes Tuesday night as we reside on the eastern periphery of an upper level ridge. This could deliver weakening showers/storms sinking southward from Pennsylvania overnight Tuesday, but again, no more than low end chance POPs exists at this time along and north of the Potomac. Lows Tuesday night will be mild in the 60s.
LONG TERM /WEDNESDAY THROUGH SUNDAY/... A warm front will push east of the area Wednesday with temperatures climbing into the 90s. Models show a maximum in sfc to 850 mb dewpoints over the area at 18Z. With all the the heat and humidity, there will be a concern for t-storms. Forcing over our area does not look particularly strong with only weak height falls indicated and no sfc boundaries present, however, models have a strong signal for one or more clusters of t-storms over ern OH and PA Wed afternoon, which would likely be severe given presence of strong westerlies (50+kt at 500 mb over PA). Outflows or cold pools generated by upstream convection may serve as trigger for additional/new convection over the area. In summary, significant uncertainty remains with respect to strength and timing of any convection Wed afternoon/night.
The front will be slow to clear the area Thu before it washes out Fri. Risk of showers/t-storms will persist Thu, especially over central Virginia. Another front is expected to cross the area Sat. The quality of moisture return ahead of this front remains uncertain this far out, but there seems to be some consensus for improving wx/drying conditions toward the end of this week or the beginning of next week.