Category Archives: Climate

NYC Midweek Weather Update – Mar 5, 2014

Just a quick update on the weather for NYC for the rest of the work week into the weekend. It’s finally going to be a quiet weather week for us after what’s been an cold and snowy February.

Tonight, a slight chance of flurries, and a cold night with fairly good conditions for radiational cooling, lows dropping into the low 20s in the city and teens in the interior. Wind chills in the single digits for Thursday morning.

Thursday – high pressure will prevail and bring sunny skies, but still a cold day with highs in the low 30s. Clouds will increase during the day with another slight chance for snow during the night into Friday morning.

Friday – cloudy with temps warming to the low 40s. As the high pressure center moves offshore, winds will shift to the west.

Saturday – increasingly warm with temps near 50 especially in coastal areas due to a northeast wind off of the relatively warmer ocean waters. A storm system will pass well to our south and east, so no precipitation is expected.

Sunday – slightly cooler with highs in the low 40s and a increasing wind from the north.

Our local NWS forecast office put together a great graphic that shows how this past February stacks up climatologically. Check it out:

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NYC Weekend Weather Update & CA Storms – Feb 27, 2014

First up for the NYC area is a bitterly cold end to the work week.

A reinforcing arctic cold front is set to push through the area during the day today, perhaps spurring a few scattered moderate-heavy snow showers. Accumulation, if any, should be light. Behind this frontal boundary, a west wind between 15-20mph will usher in some of the coldest low temps we’ve seen in recent weeks. Lows in the city are forecast to be in the low teens, with zero to single digits in the interior. Wind chill values tomorrow morning will hover around zero.

Friday will be a sunny day with high pressure moving in. Despite the sunshine, temps will struggle into the 20s across the region.

Saturday, a weak frontal system moves through, but with dry atmospheric conditions, little if any snow is expected. Highs will be in the low-mid 30s.

Sunday-Monday, a prolonged winter weather event is forecast. The storm system currently impacting the west coast (see below) will move over the interior of the country, reorganize, and strengthen over the Midwest. This will lead to a stalled cold front draping across our region with multiple low pressure centers to slide along this front. One of these is forecast to develop into a potentially significant coastal storm. Models are coming into agreement that this storm center could pass close to the 40N 70W benchmark sweet spot.

The duration of the storm, starting Sunday night through Monday night means that it could result in significant snowfall, even with possible mixing in with sleet/rain near the coast during the day Monday. Still too early to tell how much snow – will keep monitoring the situation. High temps on Sunday will be in the mid 30s, then drop back into the low 30s for Monday.

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Too much of a good thing for California?

As I noted in earlier posts, and as has been broadcast by the media, California remains in the grips of a crippling drought. A strong pacific storm system is spinning up multiple bands of heavy precipitation during the end of this week. While that is some good news for the drought, the intensity of the rainfall could lead to mudslides, and localized flooding. The best news out of this storm is that elevations over 7000′ are expected to pick up as much as 1-3′ of snow, adding to a paltry snowpack thus far. Check out the graphic from the San Diego NWS station for a look at the heavy rain fall totals expected (5-7″ in higher elevations near the coast with south facing slopes!).

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NYC Weather, Relief for CA, A Stormy Monday for NY? – Feb 25, 2014

Keeping eyes peeled on the forecast for Monday, when the next strong storm system is forecast to arrive.

First, there’s some good news for our friends out west. As you can see in this first image, the GFS model is showing a storm system originating in the Pacific bringing areas of moderate to heavy rain over the weekend for California, which is currently in the grips of an historic drought. As the storm center approaches the coast, a strong cold front will swing from south to north through the state. This frontal boundary will spark thunderstorm and rain which should bring mild relief, with 1-2″ of rain forecast for coastal and valley areas, and 2-4″ up to 6″ for south-facing mountain slopes. In addition, heavy snow could fall in the higher elevations of the coastal ranges and Sierra. Welcome news for an area of the country that’s in need of moisture.

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After the storm exits the western US, it is forecast to reorganize over the plains and Midwest, then track into our area. Right now, it’s still to early to say with certainty whether the intensity of the precipitation this storm brings, and whether it will be all snow, a mix, or even mostly rain. Will keep you all updated.

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Really Cool Graphic – Tornado Tracks from 1950-2013 Mapped

Just a super interesting graphic that the Storm Prediction Center put together using GIS data. What you’re seeing is a graphical representation of the track of each tornado that’s impacted the continental United States from 1950-2013. Notice the density in Tornado Alley, a region of the country where geography is conducive to the large scale weather patterns that produce tornadoes. Also, check out the general trend of a northeast vector to the tornado tracks. Lastly, note that although tornadoes are considerably less common in the Northeast, they still do occur with some frequency.

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NYC Weather Update, Looking Ahead & the Arctic Oscillation (AO) – Feb 20, 2014

A strong frontal system that’s currently pushing its way into the Central Plains will be arriving in our area Friday, bringing showers, potential thunderstorms, and much warmer temps. Currently, the storm system is impacting a wide swath of terrain. Blizzard warnings up for most of the state of Iowa, and heavy snow is expected across Wisconsin and Minnesota.

Though this storm will weaken somewhat before it hits our area, it should nonetheless bring widespread rain showers with the possibility for a strong thunderstorm and wind gusts up to 50mph. Temps tomorrow will range in the mid 50s with a warm front passing over tonight and southwest winds pumping in warmer air ahead of the cold front tomorrow. Timing of the cold front passage looks to be in the late morning/early afternoon. Rain showers/thundershowers could band together and form a continuous line with some embedded stronger thunderstorms. Chances of  strong thunderstorms are slim, though. As you can see below, the Storm Prediction Center in Norman, OK, placed the far reaches of southern New Jersey in its outlook for severe weather.

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Once the cold front passes, temps will regress back to average over the weekend, with temps on Saturday expected to top out around 50 under mostly sunny skies, and highs on Sunday in the mid 40s. Our reprieve from the cold will be short, however, as a reinforcing cold front will pass on Sunday, opening the door to a longer term trend of colder and below average temperatures.

You might be wondering why this has been such a cold winter for the Northeast. Well, something called the Arctic Oscillation (AO) is a contributing factor. The AO is a measure of the strength of the arctic jet stream. When the AO is positive, it means the arctic jet is strengthening. When negative, the AO signals a weakening in the arctic jet. Negative readings on the AO index generally correspond with colder surface temperatures. Why? When the arctic jet is speeding up and growing stronger, it keeps the coldest air trapped around the polar regions. When the arctic jet slows down, it allows this colder air mass to move southward, shifting the jet along with it. In extreme cases, it can even allow polar vortexes to take unusual orientations.

If you take a look at the AO Index bar graph below, you can note that the AO index was indeed negative during the latest outbreaks of bitter cold temperatures in our region.
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I bring this up because the forecast for the next 7 days indicates a return to a negative AO regime, which should lead to colder temperatures through the week. This won’t be as bad as other cold spells, since the angle of the sun is about what it would be for early October, and the days are getting longer, allowing for more daytime heating. Currently forecast highs in the Monday-Wednesday timeframe are all just under freezing for NYC.

There are some slight chances for precipitation Tuesday, but the next significant storm system looks like it will impact the area around Wednesday. Given the temperature trend, this storm should fall as mostly snow, so we’ll see how subsequent forecasts turn out on storm track and available precipitable water.

Active Weather Pattern to Bring Relief to Drought Stricken West

Weather Prediction Center’s medium range forecast

 

Over the past couple of months, exceptional drought conditions have developed over large portions of the western UnitedStates caused by prolonged periods without measurable precipitation. It was not long ago that parts of California were literally on fire.

This past week, West Coast folks finally got some relief as rain and snow fell over portions of the Pacific Northwest and California, including the Cascades and the Sierra. As of today, winter storm warnings and advisories are up for much of the same region. The snow will be critical especially for the Central Valley of California. Annual snowmelt from the Sierra feeds the rivers and streams that farmers depend on to grow the abundant veggies and fruits that we get to enjoy across the nation.

This active weather pattern will continue for the west coast, with another area of low pressure forecast to slide southeast from the northeastern Pacific Ocean by Tuesday (see above). However, the long-term drought outlook still calls for persistence or deterioration. Either way, people out on the west coast are probably happy to see any precipitation.