The SI Weather
23Apr/14Wed

7:00 AM | Much cooler today with strong NW winds; another night with lows not far from the freezing mark

6-Day Forecast

Today

Partly-to-mostly sunny, windy and much cooler than yesterday, gusts up to 40 mph or so, highs in the upper 50’s

Tonight

Mostly clear, breezy and downright cold, lows not far from freezing by morning with possible patchy frost late

Thursday

Mostly sunny, still quite breezy and on the cool side, low 60’s

Thursday Night

Mostly clear, chilly, upper 30’s

Friday

Mostly cloudy, breezy, milder, chance for a few showers, mid-to-upper 60’s

Saturday

Partly sunny, breezy, mild, maybe a shower, upper 60’s

Sunday

Mostly sunny, breezy, cooler, low 60's

Monday

Increasing clouds, cool, chance for showers at night, low 60’s

Discussion

The big weather story of the day will be the strong NW winds that can gust up to 40 mph or so at times. These winds will flood the Mid-Atlantic region with a much cooler air mass compared to yesterday following the passage of a strong cold frontal system late yesterday that brought with it numerous showers and thunderstorms. Temperatures will hold in the 50’s this afternoon despite some sunshine along with those stiff NW winds and low temperatures by early tomorrow morning will once again approach the freezing mark in many areas. It’ll continue on the cool side on Thursday, but milder conditions are likely at the end of the work week and during the beginning of the upcoming weekend before it turns cooler again early next week.

Looking ahead and to put it simply - next week is looking ugly. A large-scale upper level trough will set up shop in the eastern U.S. by the middle-to-latter part of next week and this will lead to an extended period of cool and unsettled weather with the threat for rain over several days. In fact, it'll likely be cold enough later next week in parts of the central/northern Plains and Upper Midwest for some more late season snow to fall in those areas during next week's cool and unsettled weather pattern.

Video

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23Apr/14Wed

7:00 AM | Much cooler today with strong NW winds

6-Day Forecast

Today

Partly sunny, windy and much cooler, gusts up to 40 mph or so, highs in the upper 50’s

Tonight

Partly cloudy, windy and cold, lows in the upper 30's by morning

Thursday

Mostly sunny, still quite breezy and on the cool side, low 60’s

Thursday Night

Mostly clear, chilly, near 40

Friday

Mostly cloudy, breezy, a bit milder, chance for a few showers, mid 60’s

Saturday

Partly sunny, breezy, mild, maybe a shower, mid-to-upper 60’s

Sunday

Mainly sunny, breezy, cooler, near 60

Monday

Partly sunny, cool, chance for showers at night, low 60’s

Discussion

The big weather story of the day will be the strong NW winds that can gust up to 40 mph or so at times. These winds will flood the Mid-Atlantic region with a much cooler air mass compared to yesterday following the passage of a strong cold frontal system late yesterday that brought with it numerous showers and thunderstorms. Temperatures will hold in the 50’s this afternoon despite some sunshine along with those stiff NW winds and low temperatures by early tomorrow morning will once again bottom out in the 30's in many areas. It’ll continue on the cool side on Thursday, but milder conditions are likely at the end of the work week and during the beginning of the upcoming weekend before it turns cooler again early next week.

Looking ahead and to put it simply - next week is looking ugly. A large-scale upper level trough will set up shop in the eastern U.S. by the middle-to-latter part of next week and this will lead to an extended period of cool and unsettled weather with the threat for rain over several days. In fact, it'll likely be cold enough later next week in parts of the central/northern Plains and Upper Midwest for some more late season snow to fall in those areas during next week's cool and unsettled weather pattern.

Video

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23Apr/14Wed

7:00 AM | Much cooler today with strong NW winds; 30′s again for lows in the overnight hours

6-Day Forecast

Today

Mostly sunny, windy and much cooler than yesterday, gusts up to 40 mph, highs in the low 60’s

Tonight

Mostly clear, breezy and cold, lows in the mid-to-upper 30’s

Thursday

Mostly sunny, still quite breezy and on the cool side, mid-to-upper 60’s

Thursday Night

Mostly clear, chilly, mid 40’s

Friday

Mainly cloudy, breezy, milder, chance for a few showers, low 70's

Saturday

Mainly sunny, breezy, quite mild, mid 70’s

Sunday

Mostly sunny, breezy, cooler, low-to-mid 60's

Monday

Mostly cloudy, cool, chance for showers at night, low 60’s

Discussion

The big weather story of the day will be the strong NW winds that can gust up to 40 mph or so at times. These winds will flood the Mid-Atlantic region with a much cooler air mass compared to yesterday following the passage of a strong cold frontal system late yesterday that brought with it numerous showers and thunderstorms. Temperatures will struggle to pass 60 degrees this afternoon despite some sunshine along with those stiff NW winds and low temperatures by early tomorrow morning will once again bottom out in the 30's in most areas. It’ll continue on the cool side on Thursday, but milder conditions are likely at the end of the work week and during the beginning of the upcoming weekend before it turns cooler again early next week.

Looking ahead and to put it simply - next week is looking ugly. A large-scale upper level trough will set up shop in the eastern U.S. by the middle-to-latter part of next week and this will lead to an extended period of cool and unsettled weather with the threat for rain over several days. In fact, it'll likely be cold enough later next week in parts of the central/northern Plains and Upper Midwest for some more late season snow to fall in those areas during next week's cool and unsettled weather pattern.

Video

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22Apr/14Tue

11:50 AM | El Nino likely on the way, but odds are against a “super” one

ENSO_fcsts
[computer model forecasts courtesy International Research Institute at Columbia University]

Discussion

Summary
El Nino, which refers to warmer-than-normal waters in the central and eastern tropical Pacific Ocean, can have an important effect on global weather patterns; especially, if it develops into what is commonly referred to as a “super” El Nino. In fact, we have had “super” El Nino’s in the tropical Pacific Ocean in the not too distant past (e.g., 1997-1998, 1982-1983) which caused global temperatures to spike to well above normal levels for a sustained period of time. Indeed, there are numerous signs that an El Nino is likely to develop this summer in the tropical Pacific Ocean and continue into the fall season and it is likely to have an impact on the upcoming tropical season in the Atlantic Basin. Many are suggesting that this potential El Nino will evolve into a “super” El Nino; however, I believe the odds are against that and I provide some of the reasoning in this discussion and also in the video (below).

Reasoning against a "super" El Nino
Several dynamical computer forecast models tend to develop an El Nino during the summer months in the tropical Pacific Ocean, but then project it to level out or even weaken as we approach the late fall and upcoming winter season. One model in particular that I track from Japan called the JAMSTEC has a pretty good track record with respect to El Nino forecasting and while it does predict an El Nino to develop during the summer months and continues it through the fall season, it then tends to weaken it heading into the upcoming winter season. Also, if one looks at the recent history of the “multivariate El Nino Southern Oscillation (ENSO) index”, it is generally the case that “super” El Nino’s tend to follow relatively warm periods with weak El Nino conditions in the tropical Pacific Ocean whereas weaker El Nino’s tend to follow relatively cold periods (i.e., La Nina conditions). The last few years have in fact been dominated by La Nina (cold) conditions in the tropical Pacific Ocean which is supporting evidence that a “super” El Nino is less likely to form. Finally, another important index that meteorologists track with regard to the state of the tropical Pacific Ocean is called the Southern Oscillation Index (SOI). This index gives an indication of the development and intensity of El Nino or La Nina events in the tropical Pacific Ocean and it is calculated using the pressure differences between Tahiti and Darwin. If there are negative values of the SOI then this can be indicative of upcoming El Nino episodes. A “long-lasting and sharply negative” SOI value can be a useful predictor of a very strong or “super” El Nino. Currently, the SOI values that we are observing are nowhere near the values experienced during or just preceding the “super” El Nino years of 1982-1983 and 1997-1998.

Potential winter implications
One final note, the difference between a weak and “super” El Nino can be huge when it comes to impact on winter weather in the Northeast US. An ongoing “super” El Nino next winter would increase the odds of a warm winter in the Northeast US whereas a weaker El Nino - especially one based in the central tropical Pacific Ocean - can still allow for a cold and snowy winter (more on that outlook at a later time).

Video

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