Good morning and happy Friday! High pressure slides just offshore with a return southerly flow into the Northeast states today. This flow will help temperatures to moderate a bit as the morning goes on, but sunshine will begin to fade behind increasing clouds. A low pressure system approaches with a warm front moving east from the Ohio Valley into the Northeast states, signaling the approach of a transient storm system today.
The high pressure we mentioned should keep the I-95 major cities dry, but some light snow is expected over parts of Northern PA, Upstate New York and into New England this afternoon and early tonight as the warm front passes through. Be prepared for some slippery roads with light snow accumulations possible in these areas. Otherwise, mostly cloudy skies remain stagnant throughout the Northeast for the rest of the night. Temperatures will hold steady or slowly rise from daytime highs late tonight as warm-air advection increases.
Temperatures will continue to moderate to above normal levels in the Northeast this weekend with a deeper southwesterly flow. Highs each day will be in the lower to middle 50s. Unsettled and wetter weather is likely over the weekend, as a frontal zone associated with a large trough slowly approaches from the west. Cloud cover will likely dominate again with any sunshine being limited on Saturday. Some rain showers or drizzle may begin developing during the afternoon and evening hours.
Then, multiple waves of low of pressure moving northward along the frontal zone will cause periods of rain later Saturday night and Sunday. Some locally heavy rainfall between 1” to 3” is possible from the Mid Atlantic through New England with a strong low-level southwesterly jet and highly anomalous precipitable water values for this time of year. This may lead to some localized flooding in poor drainage or low-lying areas.
Periods of rain could still continue into Sunday night and early Monday before the frontal zone begins moving offshore. Overall – a really dreary weekend. High pressure builds in behind the front, with colder and drier weather returning later Monday and Tuesday. With that said, the progressive pattern will continue, with zonal heights or ridging returning to the Northeast, allowing for temperatures to moderate for a few days again later next week.
As we look ahead towards the end of February and March, high-latitude blocking and Eastern Pacific ridging develops and begins forcing the tropospheric polar vortex south into Hudson Bay and Southeast Canada. This will allow for lower heights and a baroclinic zone (temperature gradient) in between, with some ridging remaining over the Southern US. All of this adds up to the suggested potential for increasing winter weather threats from the Midwest to the Northeast as the end of February approaches.
Stay tuned for additional updates through the weekend with more thoughts and discussion on the pattern moving forward.