|Dew Point:||17.6°F (-8.0°C)|
|Sea Level Pressure:||28.56" (966.9 mb)|
SunnyHigh: 66 Low: 52
RainHigh: 58 Low: 38
Mostly SunnyHigh: 51 Low: 38
SunnyHigh: 57 Low: 40
SunnyHigh: 62 Low: 49
Sunny, with a high near 66. South wind around 9 mph.
A chance of rain after 5am. Partly cloudy, with a low around 52. South wind around 9 mph. Chance of precipitation is 40%. New rainfall amounts less than a tenth of an inch possible.
Rain. Mostly cloudy, with a high near 58. Southwest wind 7 to 14 mph, with gusts as high as 23 mph. Chance of precipitation is 90%. New rainfall amounts between a quarter and half of an inch possible.
A chance of rain before 8pm. Partly cloudy, with a low around 38. West wind 13 to 16 mph, with gusts as high as 24 mph. Chance of precipitation is 30%. New rainfall amounts less than a tenth of an inch possible.
Mostly sunny, with a high near 51. Northwest wind 13 to 17 mph, with gusts as high as 30 mph.
Partly cloudy, with a low around 38.
Sunny, with a high near 57.
Mostly clear, with a low around 40.
Sunny, with a high near 62.
... High pressure will move offshore tonight. A strong surface low pressure system will develop and move across the Ohio Valley on Wednesday, then re- develop over southeastern Virginia, before moving up the east coast towards New England Wednesday night into Thursday. High pressure returns Friday into the weekend.
NEAR TERM /THROUGH TONIGHT/... High pressure will move offshore this evening. Anticipate light south winds this evening and mid-high level clouds spilling north overnight. However, guidance consensus keeps the area dry through dawn. Even the ECMWF has backed off, although its still further northeast than its counterparts. Am keeping chance PoPs from W99-CHO at daybreak to account for this timing spread.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... Deep mid/upper level low pressure and its surface reflection will rotate through the Great Lakes Wednesday, sending a cold front toward the forecast area. Meanwhile, southern stream energy will instigate secondary low pressure ejecting into the Atlantic. As the mid level trough tilts negatively, energy will transfer offshore. Deep cyclogenesis will result. While there is still spread with respect to which stream will dominate, for Maryland and Virginia there is good consensus that rainfall will begin during the morning hours, and the cold front will cross during the afternoon. Instability will be negligible but non- zero. However, there is plenty of shear and strong baroclinic forcing. Believe the best opportunity for rain will come within a few hours of frontal passage...which will likely be during the afternoon. Model sounding do reveal 40-50 kt of winds around 5000 ft aloft, but the air mass will be saturated and an inversion will be present between 925-850 mb. Mixing will be poor. Some gusty winds may accompany fropa. Still have categorical PoPs emphasizing the best timing. Have chance rain lingering into Wednesday evening along I-95, only to account for timing differences. The actual end of precip should be rather sharp.
Behind the front, concerns will switch to wind, temperatures, and upslope precipitation. Temperatures at 850 mb will turn subzero across the board soon after midnight early Thursday morning. Consequently have lowered low temps Thursday and Friday morning. Momentum transfer generally not that great at night, but believe there will be more than enough air mass change to keep gusts going through the night. Am uncertain about the valleys, but gusty winds should hit the ridge tops through the night. Not sure if this will be Wind Advisory threshold winds or just a breezy night. Have increased gusts but kept winds sub Advisory for now. Still have 12-24 hours to monitor.
The wind direction and temperatures will be upslope favorable, and have increased mountain PoPs. Have mention of accumulating snow across the Appalachian ridge tops, but warm ground and only marginal thermal profiles should keep it to an inch or two. Unlike the NAM BUFKIT output, am not forecasting accumulating snow during Thursday afternoon (although flakes may fall).
LONG TERM /FRIDAY THROUGH TUESDAY/... High pressure will be overhead Friday and Saturday leading to sunny skies and dry conditions. Temperatures will be chilly at night with lows in the 30s/40s, and near to slightly below normal during the day, with highs in the 60s.
The surface high will then slide offshore on Sunday with southwesterly return flow developing. This will usher in increasing warmth, to be followed by increasing moisture. There remains uncertainty in the evolution of a system that ejects northeastward from the Plains and into the Great Lakes, and the potential southern stream system that may originate in the Gulf. 15/00z ECMWF brings in precipitation as early as Sunday, while 15/12z GFS/CMC hold off until Monday. Either way, rain chances will be increasing late in the weekend and especially early next week as the systems move northeastward. The cold front associated with the primary system looks to move through the area on Tuesday. Temperatures will skew above normal, although actual highs will be dependent on amount of rain. Will show low 70s Sunday-Tuesday.