The SI Weather
15Apr/14Tue

7:00 AM | **After two of the warmest days so far this spring, significantly colder air moves in late today; could even see a bit of sleet or snow early tonight in suburban locations**

6-Day Forecast

Today

Periods of rain, heavy at times, maybe a thunderstorm or two mixed in, windy, mild this morning with temperatures not far from 70 degrees, but they will drop sharply later this afternoon

Tonight

Cloudy, windy and becoming much colder, lingering rain showers could even mix with or change to sleet and/or snow before ending, lows by morning near 30 degrees

Wednesday

Mostly sunny, windy and very chilly for this time of year, near 50

Wednesday Night

Mostly clear, cold, patchy frost towards morning in suburban locations, lows near freezing

Thursday

Mainly sunny, a chilly start and then a bit milder in the afternoon, upper 50’s

Friday

Mostly cloudy, chilly, upper 50’s

Saturday

Partly sunny, breezy, mild, chance of showers, low 60’s

Sunday

Partly sunny, mild, low 60’s

Discussion

After the two warmest days of the spring so far on Sunday and Monday, big changes are on the way for the eastern part of the country. An impressive cold front is moving west-to-east this morning towards the east coast and it will bring a significant rainfall to the Mid-Atlantic region along with persistently strong winds and isolated thunderstorms. The front will usher in much colder air to region by the end of the day and there is a chance that it will get cold enough for lingering rain showers to mix with or change to sleet and/or snow this evening with the greatest chance for this possible changeover in the western and northern suburbs. Temperatures by tomorrow morning will be below freezing in most Mid-Atlantic locations and patchy frost is likely early Thursday morning. This late season cold shot will be quite widespread with well below normal temperatures by tomorrow extending from Canada all the way down to the Deep South.

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14Apr/14Mon

2:00 PM | Much colder air pours into the region tomorrow night

Discussion

The latest observations show temperatures that are way above normal for this time of year in the Mid-Atlantic I-95 corridor with 80 degrees at Reagan National Airport in DC, 76 degrees in Philly, and 72 degrees at Central Park in New York City. Despite the impressive warmth of today in this region, there is actually an outside chance that sleet and/or snow are seen in these same locations tomorrow evening as much colder air pours into the area.

A powerful cold front will be moving from west-to-east towards the east coast on Tuesday and this will result in some dramatic temperatures drops behind the front as well as some significant differences across the frontal boundary zone. For example, during the mid-day hours on Tuesday, temperatures may be close to the 70 degree mark in southeastern Pennsylvania while, at the same time, they are in the 20’s in the northwestern part of the state. This frontal system will be accompanied by significant rainfall (1-2 inches) in DC, Philly and New York City along with persistently strong winds and there can be a few thunderstorms mixed into the picture.

As the colder air pours in early tomorrow night behind the passage of the frontal system, lingering rain showers can mix with or change to sleet and/or snow - even into the big cities along the I-95 corridor - but the greatest chance for this changeover to occur before the precipitation ends will be in the western and northern suburbs. In the interior, higher elevation regions of the Northeast U.S., there can even be a few inches of slushy snow later tomorrow (e.g. Appalachian Mountains). By Wednesday morning, temperatures will be at or below freezing throughout the Mid-Atlantic region and patchy frost will be possible early Thursday morning and perhaps even early Friday morning. Temperatures will then modify noticeably by the weekend.

One final note: there is a total lunar eclipse early tomorrow morning, but clouds are very likely to obscure the view in the Mid-Atlantic region; however, there will be another chance in September.

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14Apr/14Mon

7:00 AM | Another day near 80 degrees then dramatically colder by mid-week

6-Day Forecast

Today

Some sun followed by clouds, still quite warm, windy, highs near 80 degrees

Tonight

Cloudy, mild, showers likely late, temperatures only dropping to the low 60’s for overnight lows

Tuesday

Periods of rain, heavy at times, maybe a thunderstorm, windy, warm early in the day in the upper 60's, but temperatures will drop during the afternoon hours

Tuesday Night

Mostly cloudy, lingering rain showers that could even mix with or change to sleet and/or snow before ending, much colder late, windy, low 30’s

Wednesday

Partly sunny, breezy, very chilly for this time of year, near 50; patchy frost possible late at night

Thursday

Patchy frost possible early; otherwise, mostly sunny skies, still chilly, mid 50’s

Friday

Partly sunny, breezy, milder, near 60

Saturday

Mostly cloudy, breezy, mild, chance for showers, low 60’s

Discussion

The warmest weather of the spring so far in the Mid-Atlantic region will soon be replaced by a very chilly air mass for this time of year. That transition from the warmth to chill will be accompanied by a significant rain event on Tuesday as the leading edge of the colder air (i.e., cold front) slides towards the east coast. This next cold shot will become quite widespread as the colder air will spill all the way from Canada to the Deep South. Furthermore, there could be enough cold air intrusion into the eastern states to cause a changeover to sleet and/or snow in some of the interior, higher elevations of the Northeast U.S. (e.g., Appalachian Mountains) and it is not totally out of the question that the rain mixes with or changes to sleet and/or snow in the I-95 corridor before ending later tomorrow night. Overnight low temperatures will indeed drop to near or below the freezing mark in much of the Mid-Atlantic region during the mid-week time frame with patchy frost possible. The chill will continue in the Mid-Atlantic region into Thursday, but it'll turn milder late this week with the threat of showers returning by Saturday. One final note: unfortunately, it looks like it'll be cloudy early tomorrow morning for the viewing of the total lunar eclipse here in the Mid-Atlantic region, but there will be another chance in September.

Video

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11Apr/14Fri

7:00 AM | Warmest weather yet for Sunday and Monday, but significant rainfall on Tuesday ushers in a much cooler air mass

6-Day Forecast

Today

Mostly cloudy, breezy, quite mild, chance for a shower or two, but mainly rain-free, highs in the mid 70's

Tonight

Cloudy, mild, showers likely, lows near 50 degrees

Saturday

Early morning clouds give way to sunshine, mild, near 70

Saturday Night

Partly cloudy, comfortable, low 50’s

Sunday

Mostly sunny, quite mild, near 85 degrees

Monday

Becoming mostly cloudy, breezy, quite mild, chance for rain at night, upper 70’s

Tuesday

Periods of rain, breezy and turning cooler late, near 60

Wednesday

Partly sunny, breezy, much cooler and quite chilly for this time of year, low 50’s

Discussion

A cold frontal system will approach the region today giving us the chance for a shower or two, but much of the time will be rain-free. The front slows down some tonight as it grudgingly works its way through the region and the result will be a continuation of the shower threat for much of the night. The good news is that the front - and its associated clouds and showers - should move away from the region early tomorrow and this will set us up for a rather nice weekend. In fact, the warmest weather yet this spring will arrive on Sunday and continue into Monday before a significant cool down takes place later Tuesday and Wednesday. That cool down will be preceded by a strong cold front and significant rainfall is likely here late Monday night and Tuesday as the colder air mass arrives into the Mid-Atlantic region. This next cold shot will be quite widespread with the cold air plunging all the way down into the Deep South. Furthermore, snow is quite likely to break out late Tuesday in some of the interior, higher elevation locations of the Northeast U.S. (e.g., Appalachians). Unfortunately, the timing of the early week cold front is likely to greatly reduce our chances in the Mid-Atlantic region of observing the total lunar eclipse set for early Tuesday morning. The chilly weather that begins late Tuesday following the passage of the strong cold front will likely continue through Thursday, but then a warm up should then take place in the region in time for the Easter weekend.

Video

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