Synopsis:
A warm front will bring in the wintry mix tonight into tomorrow. A warm-up will commence for Tuesday before an arctic front brings rain and perhaps a few strong thunderstorms on Wednesday afternoon. A rapid cool-down will follow for the end of the work week into the weekend bringing lake-effect snow to the northwestern parts before another storm threatens for the weekend.
Models Used: 18Z GFS, 00Z NAM & Hi-Res NAM, 01Z HRRR
Monday - Wintry Mix:
The 546-DM 500-1000-mb thickness line looks to be the snow-to-freezing-rain line, and the 32°F isotherm will be the rain-to-freezing-rain line. The freezing line will arrive a few hours after the 546-line arrives, and those times are:
Pittsburgh around 2:30 (546) & 5:00 (32F) AM
State College around 8:00 (546) & 11:00 (32F) AM
Scranton around 11:00 AM (546) & 2:30 PM (32F).
The precipitation will last about eight hours for most locations, but a little longer for the Laurel Highlands. Accumulations of snow & sleet will be around one or two inches (locally 3") with ice accumulations of a coating to 1/10" in most of PA (except for interior parts of the northwest and north-central zones where they'll see 1/4" of ice!). Travel will be VERY treacherous.
Tuesday - Warm-Up:
Temperatures at 850-mb will be 8°C, which is about 25-30 degrees Celsius higher than they were on Tuesday. For State College, the surface temperature using the DALR (9.8°C per km) translates to about 65-66 degrees Fahrenheit at the surface. Nice! But there are consequences to the warm-up: a cold front will not only bring rain, but also thunderstorms (some strong) to many areas on Wednesday. Models are also hinting at scattered shower activity for the day on Tuesday due to some instability.
Wednesday - Thunderstorms:
The cold front will arrive in Western PA for the early afternoon hours, and have passed through the Commonwealth around midnight. As the front passes, temperatures at 850 mb will drop as much as 1°C per hour! With those temperature profiles occurring at the peak heating of the day, most of southern and western PA will see intense thunderstorms with heavy rain and gusty winds.
End of Week - Cool-Down & Lake-Effect Snow:
The northwest flow and temperatures at 850 mb returning to the -15 to -20 degree Celsius mark will lead to lake-effect snows across the northern and western areas of the state.
-Jaron Breen
A warm front will bring in the wintry mix tonight into tomorrow. A warm-up will commence for Tuesday before an arctic front brings rain and perhaps a few strong thunderstorms on Wednesday afternoon. A rapid cool-down will follow for the end of the work week into the weekend bringing lake-effect snow to the northwestern parts before another storm threatens for the weekend.
Models Used: 18Z GFS, 00Z NAM & Hi-Res NAM, 01Z HRRR
Monday - Wintry Mix:
The 546-DM 500-1000-mb thickness line looks to be the snow-to-freezing-rain line, and the 32°F isotherm will be the rain-to-freezing-rain line. The freezing line will arrive a few hours after the 546-line arrives, and those times are:
Pittsburgh around 2:30 (546) & 5:00 (32F) AM
State College around 8:00 (546) & 11:00 (32F) AM
Scranton around 11:00 AM (546) & 2:30 PM (32F).
The precipitation will last about eight hours for most locations, but a little longer for the Laurel Highlands. Accumulations of snow & sleet will be around one or two inches (locally 3") with ice accumulations of a coating to 1/10" in most of PA (except for interior parts of the northwest and north-central zones where they'll see 1/4" of ice!). Travel will be VERY treacherous.
Tuesday - Warm-Up:
Temperatures at 850-mb will be 8°C, which is about 25-30 degrees Celsius higher than they were on Tuesday. For State College, the surface temperature using the DALR (9.8°C per km) translates to about 65-66 degrees Fahrenheit at the surface. Nice! But there are consequences to the warm-up: a cold front will not only bring rain, but also thunderstorms (some strong) to many areas on Wednesday. Models are also hinting at scattered shower activity for the day on Tuesday due to some instability.
Wednesday - Thunderstorms:
The cold front will arrive in Western PA for the early afternoon hours, and have passed through the Commonwealth around midnight. As the front passes, temperatures at 850 mb will drop as much as 1°C per hour! With those temperature profiles occurring at the peak heating of the day, most of southern and western PA will see intense thunderstorms with heavy rain and gusty winds.
End of Week - Cool-Down & Lake-Effect Snow:
The northwest flow and temperatures at 850 mb returning to the -15 to -20 degree Celsius mark will lead to lake-effect snows across the northern and western areas of the state.
-Jaron Breen
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