Thomas is an avid weather enthusiast, landscaper and organic gardener. This blog is dedicated to Northeast and tropical weather forecasting. Enjoy!
By: sullivanweather , 2:37 PM GMT on November 18, 2012
Current watches, warnings and advisories.
Current watches, warning and advisories issued by the National Weather Service. Courtesy of NOAA.
East Coast IR satellite image.
Stunning late-autumn weather will continue right through the Thanksgiving holiday for most locales across the Northeast thanks to a sprawling high pressure ridge axis draped across eastern North America. Aside from thin high cloudiness due to the passage of a couple very weak ripples in the jet, skies will tend to be mostly sunny right through Thanksgiving with temperatures running several degrees above seasonal norms. A significant cold frontal passage will take place Black Friday which should bring the coldest weather of the season in its wake and perhaps the first significant lake effect event for the Snow Belt region over the weekend. As we head into the last week of November a strong omega ridge is forecast to develop at high latitudes over the Dateline and slowly retrograde toward eastern Siberia. This pattern should draw down a significant chunk of arctic air building over Alaska and Northwestern Canada into the Rocky Mountain region as downstream troughing digs in the western United States, spawning a strong winter storm over the Plains by midweek. Ahead of this trough broad southwesterly flow should develop across the eastern half of the country, bringing a warming trend to the Northeast region for the first half of the week. However, the second half of the week looks stormy as the Plains storm moves in.
Mostly sunny skies and frosty lawns will greet Northeast residents this Sunday morning. Temperatures will begin the day in the 20's across much of the interior with mainly 30's along the coastal plain. The urban centers are in the low 40's, with Philadelphia checking in at 41°F for the start of the Philadelphia marathon this morning. Sunny skies will quickly warm temperatures through the morning into the early afternoon, with low to mid 50's expected for highs along the coastal plain up to southern New England, west of the Appalachians and across the Great Lakes plain and most interior valleys. At elevations higher than 1000' temperatures should remain in the mid to upper 40's. High clouds will start to spread across southeastern Pennsylvania and southern New Jersey during the afternoon as low pressure develops off the coast. Mainly clear skies, dry air, and light winds will continue through this evening across the interior allowing temperatures to plummet once again into the 20's overnight. Along the coastal plain, however, a thickening layer of high clouds will slow the temperature fall some with lows in the upper 30's to low 40's.
Not much in the way of changes for Monday with sunny skies continuing to reign across the interior and high clouds persisting along the coast to start the day. A weak disturbance will approach from the west during the afternoon spreading high cloudiness into the interior as well but temperatures will once again reach into the low to mid 50's along the coastal plain, lake plain and interior valleys with 40's at higher elevations across the interior. High clouds continue to move into the region Monday night helping to keep temperatures several degrees warmer than nights prior. Expect lows in the upper 20's to low 30's across the interior with upper 30's to low 40's along the coastal plain.
More in the way of cloud cover over the region on Tuesday as the weak upper trough passes trough. This will keep temperatures a bit lower than today or Monday but they will still run several degrees above normal for latter November. The weak trough will make its way off the coast Tuesday night with thinning clouds as the night progresses. Low temperatures will once again fall into the 20's across most of the interior with upper 30's to low 40's for the coastal plain.
Clouds will continue to abate on Wednesday for most locales as sunny skies return for the biggest travel day of the year. The lone exception will be along the immediate coasts of southern New England to Long Island where a piece of energy rotating around the offshore low pressure will keep skies mostly cloudy. Otherwise it will be a splendid day with temperatures approaching 60°F west of the Appalachians around Pittsburgh. Highs in the 50's will be seen along the coastal plain and much of the interior aside from central/northern New England. These highs will be about 8-12 degrees above normal for this time of year. Thanksgiving is likely to be a carbon copy of Wednesday, though with the system offshore finally pulling away all areas should see mostly sunny skies. With the clear skies and light winds expected nighttime temperature should fall close to normal Wednesday night but remain several degrees warmer than average Thursday night as moisture increases over the region ahead of an approaching trough.
Our run of fabulous weather will be coming to an end after Friday as a potent but moisture-starved shortwave trough moves into the region from the Great Lakes. Southwesterly flow ahead of the trough on Friday will pump one final push of fairly warm air into the Northeast, with highs expected to climb into the low 60's for many of the lower elevation areas outside of central/northern New England and even here temperatures should reach into the 50's. By the afternoon hours a strong cold front associated with this trough will reach the western half of the region. Though moisture is lacking, fairly strong dynamics will force a narrow line of showers along this boundary and there even cloud be a rumble of thunder along the I-90 corridor from Buffalo to Syracuse on south to north-central Pennsylvania. The core of the mid/upper disturbance will curl north into Canada, leaving little forcing for any precipitation east of the Appalachians down to the southern coastal plain. But as the front pulls offshore it will start to draw Atlantic moisture into eastern New England Friday night, bringing a steadier rainfall to eastern Massachusetts, New Hampshire and Maine which should end as snow showers away from the coast behind the front. As low pressure wraps up over eastern Canada and much colder air flows into the Northeast, the cold cyclonic flow will promote the development of lake effect snows downwind of Lake Erie and Ontario. Trajectory at this time appears to be between 300-310° which should favor the Syracuse region and areas to the southeast of there off Lake Ontario. Off Lake Erie areas southwest of Buffalo and down the spine of the Alleghenies to the Laurel Highlands will be favored although a few streamers off Georgian Bay may make their down into the Niagara Frontier and the Buffalo region. Flow will start to turn anti-cyclonic by Sunday which should shut down the lake effect machine to close out the weekend. The coldest air of the season for the Northeast by far will arrive this weekend. Temperatures may not climb above freezing for much of the higher terrain of the Northeast and areas within the lake effect snow bands. Elsewhere across the interior high temperatures will be in the 30's with upper teens to low 20's at night. Along the coastal plain highs should make it to the low 40's with upper 20's to low 30's at night. A brisk wind Saturday and Saturday night will add an extra bite to the air and wind chills could drop into the single digits across the interior Saturday night.
Radar: Northeast Region Loop
Radar loop of the Northeast region. Courtesy of Weather Underground.
Sea-surface temperatures off the Northeast Coast. Courtesy of NOAA.
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