Synopsis:
We are between low pressure over Maine and high pressure over Missouri, creating windy conditions until the end of the work week. For tomorrow through Thursday, a series of upper-level disturbances will touch off a few showers (sometimes wintry late-night). On Thursday and Friday, the wind will die down and temperatures will begin to recover as the high heads east throughout the week.
Models Used: 12Z NAM & GFS (watch out for their fast tendencies); MOS is ok, but adjust values a few degrees downward.
Short-term - Windy, Cool and Unsettled:
Advection of upper-level vorticity maxima will be the cause of the wet pattern. The jet stream's trough axis goes through PA and 1000-500-mb thicknesses are well below 540 Dm. Forecast soundings (thickness lines and isotherms will not work) indicate that the freezing altitude at night will be 900 mb (over State College), the surface temperature only 3°C, & Relative humidity will be close to 100% from 625 mb to the surface. The snow should change back to rain after sunrise.
Long-range - Transition to Warmer and Drier:
The jet stream will retreat northward and thicknesses will begin to recover as high pressure builds in from the eastern Plains late-week. The sun will return Thursday late-PM and clear skies appear to dominate through the weekend. The jet stream's ridge axis will be over PA on Saturday; the 540-Dm thickness line will be in southern Canada again. Temperatures should return to the 60s on Friday.
- Jaron Breen
We are between low pressure over Maine and high pressure over Missouri, creating windy conditions until the end of the work week. For tomorrow through Thursday, a series of upper-level disturbances will touch off a few showers (sometimes wintry late-night). On Thursday and Friday, the wind will die down and temperatures will begin to recover as the high heads east throughout the week.
Models Used: 12Z NAM & GFS (watch out for their fast tendencies); MOS is ok, but adjust values a few degrees downward.
Short-term - Windy, Cool and Unsettled:
Advection of upper-level vorticity maxima will be the cause of the wet pattern. The jet stream's trough axis goes through PA and 1000-500-mb thicknesses are well below 540 Dm. Forecast soundings (thickness lines and isotherms will not work) indicate that the freezing altitude at night will be 900 mb (over State College), the surface temperature only 3°C, & Relative humidity will be close to 100% from 625 mb to the surface. The snow should change back to rain after sunrise.
Long-range - Transition to Warmer and Drier:
The jet stream will retreat northward and thicknesses will begin to recover as high pressure builds in from the eastern Plains late-week. The sun will return Thursday late-PM and clear skies appear to dominate through the weekend. The jet stream's ridge axis will be over PA on Saturday; the 540-Dm thickness line will be in southern Canada again. Temperatures should return to the 60s on Friday.
- Jaron Breen
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