Synopsis:
The polar jet and subtropical jet merge over eastern PA, allowing a surface high to set up under the sinking air. During the course of the week, a series of short-waves will change the upper air pattern from zonal to trough. The shortwaves responsible occur on: Today in upstate NY, tomorrow night (Mon) in MD & VA, Tuesday night into Wednesday (snow over PA), and Thursday AM (clouds over MD & VA). The trough takes shape on Friday while the NE US is under a high pressure system. In the long-range, a nor'easter heads out to sea on Sunday... something to watch.
Between each shortwave, high pressure is not to far away - situated in the mid-Mississippi River Valley.
Models Used: At the advice of the HPC, we used a 12Z ECMWF & GFS blend to account for the blocking. We went with MOS most of the time, except for Wednesday (GFS 2-m Temp). Once the four-day includes Saturday night through Monday AM, the use of the model outputs (2-m Temp) is highly recommended.
Short-term:
A confluent pattern has set-up: the northern branch of the jet stream is heading SE into the southern branch of the jet stream, which turns from a NE trajectory to an Eastbound trajectory. This sets up a confluent pattern - think of the three rivers in Pittsburgh: it's the same here - with definite sinking air over eastern PA and much of NJ. A series of shortwaves will make their way along the southern branch... creating a zonal flow and then a trough. One of those is currently affecting upstate NY.
The next shortwave will create clouds and drizzle south of the State in parts of MD, VA and NC.
Shortwave number 3 will bring a wintry mix to the State on Wednesday: from the wee hours into the early evening.
Long-term:
The last shortwave will bring clouds to parts of MD, VA, and NC from sunrise 'til noon on Thursday.
The high pressure will head north then east during the forecast period. The high that will settle near southern VT & NH during the end of the week will be moderately strong. The low - developing near Savannah, GA - will head NNE and then turn toward the NE as it passes Cape Hatteras.
High goes from 1022 mb to 1030 mb heading ENE while the Low goes from 1004 to 994 mb as it heads up the coast. It is far in advance, but (1) the long-range models predicted this scenario last week (over2 weeks out)!!! and (2) it could trend westward (toward the coast) over the course of the week.
-Jaron Breen
The polar jet and subtropical jet merge over eastern PA, allowing a surface high to set up under the sinking air. During the course of the week, a series of short-waves will change the upper air pattern from zonal to trough. The shortwaves responsible occur on: Today in upstate NY, tomorrow night (Mon) in MD & VA, Tuesday night into Wednesday (snow over PA), and Thursday AM (clouds over MD & VA). The trough takes shape on Friday while the NE US is under a high pressure system. In the long-range, a nor'easter heads out to sea on Sunday... something to watch.
Between each shortwave, high pressure is not to far away - situated in the mid-Mississippi River Valley.
Models Used: At the advice of the HPC, we used a 12Z ECMWF & GFS blend to account for the blocking. We went with MOS most of the time, except for Wednesday (GFS 2-m Temp). Once the four-day includes Saturday night through Monday AM, the use of the model outputs (2-m Temp) is highly recommended.
Short-term:
A confluent pattern has set-up: the northern branch of the jet stream is heading SE into the southern branch of the jet stream, which turns from a NE trajectory to an Eastbound trajectory. This sets up a confluent pattern - think of the three rivers in Pittsburgh: it's the same here - with definite sinking air over eastern PA and much of NJ. A series of shortwaves will make their way along the southern branch... creating a zonal flow and then a trough. One of those is currently affecting upstate NY.
The next shortwave will create clouds and drizzle south of the State in parts of MD, VA and NC.
Shortwave number 3 will bring a wintry mix to the State on Wednesday: from the wee hours into the early evening.
Long-term:
The last shortwave will bring clouds to parts of MD, VA, and NC from sunrise 'til noon on Thursday.
The high pressure will head north then east during the forecast period. The high that will settle near southern VT & NH during the end of the week will be moderately strong. The low - developing near Savannah, GA - will head NNE and then turn toward the NE as it passes Cape Hatteras.
High goes from 1022 mb to 1030 mb heading ENE while the Low goes from 1004 to 994 mb as it heads up the coast. It is far in advance, but (1) the long-range models predicted this scenario last week (over2 weeks out)!!! and (2) it could trend westward (toward the coast) over the course of the week.
-Jaron Breen
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