The SI Weather
30Jul/14Wed

7:00 AM | Comfortable conditions continue around here with a downright cool start to the day

6-Day Forecast

Today

Mainly sunny, pleasant, highs near 80 degrees

Tonight

Partly cloudy, comfortably cool, lows by morning in the upper 50’s

Thursday

Mostly sunny, still quite comfortable, low 80’s

Thursday Night

Partly cloudy, cool, near 60

Friday

Partly sunny, more humid, chance for a couple of showers and possibly a thunderstorm, low 80’s

Saturday

Mostly cloudy, cooler-than-normal, chance for a couple of showers and possibly a thunderstorm, near 80

Sunday

Mostly cloudy, still cooler-than-normal, chance for showers and thunderstorms, low 80’s

Monday

Partly sunny, warm, humid, chance for showers and thunderstorms, low-to-mid 80’s

Discussion

Our spectacular late July weather continues today with low humidity values and although it will be a tad warmer than yesterday, temperatures will remain below normal for this time of year. High pressure in control of our weather will move off the Northeast US coastline by the end of the week and the return flow of air on its backside will promote increasing humidity in the area as an ocean flow of air develops.

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29Jul/14Tue

7:00 AM | A comfortable air mass is now in control

6-Day Forecast

Today

Partly sunny, pleasant, an isolated shower cannot be ruled out, highs in the upper 70’s

Tonight

Mostly clear, comfortably cool, lows by morning in the mid-to-upper 50’s

Wednesday

Mostly sunny, a tad warmer, but still below-normal for this time of year, near 80

Wednesday Night

Mostly cloudy, cool, upper 50’s

Thursday

Mostly sunny, pleasant, low 80’s

Friday

Partly sunny, more humid, chance for a shower or thunderstorm, low 80’s

Saturday

Mostly cloudy, humid, still below-normal temperatures, chance for a couple of showers and a thunderstorm, near 80

Sunday

Mostly cloudy, still cooler-than-normal, chance for showers and thunderstorms, low 80's

Discussion

A strong cold front passed through the region yesterday paving the way for a stretch of very comfortable weather conditions. Temperatures today will have a hard time escaping the 70’s in much of the Mid-Atlantic region and the below-normal temperatures will continue through much of the week. Humidity levels will also be way down for the next couple of days, but will increase at the end of the week as an ocean flow develops.

Video

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28Jul/14Mon

7:00 AM | Another spectacular low-humidity air mass for this time of year moves into the region

6-Day Forecast

Today

A mix of clouds and sun, not as warm or as humid as yesterday, chance for an additional shower or thunderstorm this afternoon, highs close to 80 degrees

Tonight

Partly cloudy, comfortable, lows by morning in the upper 50’s

Tuesday

Mostly sunny, pleasantly cool for this time of year, upper 70’s

Tuesday Night

Mostly clear, quite cool, mid 50’s

Wednesday

Partly sunny, still cool, cannot rule out an afternoon shower or two, near 80

Thursday

Mostly sunny, nice, low 80’s

Friday

Partly sunny, more humid, chance for a shower or thunderstorm, near 80

Saturday

Mostly cloudy, still cooler-than-normal, chance for a shower or thunderstorm, near 80

Discussion

Powerful thunderstorms pounded the Mid-Atlantic region in the overnight hours ahead of an approaching cold front and that frontal system will works its way through the region later today. The frontal passage will usher in another spectacular air mass for this time of year with low humidity values and comfortable temperatures. The cooler air, anchored by strong Canadian high pressure and below-normal for this time of year, will become quite noticeable later tonight and it should stay quite comfortable for the next few days.

Video

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27Jul/14Sun

12:45 PM | **Could be a wild night in the Mid-Atlantic region**

GFS
[GFS computer model forecast map at 300 mb for later tonight showing an impressive jet streak and upper level wave]

Discussion

The combination of a vigorous upper level wave, impressive jet streak and developing low pressure will generate a wild scene tonight throughout the Mid-Atlantic region with numerous showers and thunderstorms from early evening through late tonight. Some of the thunderstorms will reach severe limits with torrential rainfall, damaging wind gusts, possible hail and even isolated tornadoes. The greatest chance for severe weather tonight will likely be from the eastern part of the Ohio Valley eastward to the Appalachian Mountains, but severe weather potential exists as well into the I-95 corridor from DC-to-Philly-to-New York City.

The timetable for the shower and thunderstorm threat is approximately from 8pm to 3am. All of this activity is associated with an usually strong and widespread cold air outbreak for this time of year that will bring spectacular weather to the Mid-Atlantic region from Tuesday through the rest of the week, but we may have to pay a price before we get there.

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