Tag Archives: meteorology

NYC Weekend Weather & West Coast Storm – Dec 2, 2014

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It’s been a up and down week for weather in NYC, with Monday starting out in the mid-60s, then a colder mid-week that featured some mixed precipitation and rain. The end of this week will feature rain and slightly warmer temperatures by Saturday, then a return to colder conditions Sunday into next week. I’m also going to point out some of the spectacular weather brought on by a huge Pacific storm that hit California this week.

Thursday – the remainder of today will be pleasant and sunny, though cold with high temps only in the low 40s.

Friday – clouds will begin to build overnight tonight ahead of the a storm system moving in from the Southern Plains to the Ohio Valley. There is a small chance for scattered showers, otherwise expecting a cloudy day with highs in the mid-40s.

Saturday – rain should overspread the area by Friday night into Saturday. This storm system will be drawing on energy and moisture from the Pacific storm that slammed California earlier this week (discussed below). Combined with influx of Gulf moisture, this setup favors a moderate to at times heavy rain event for Saturday. Temperatures will rise steadily ahead of this storm system as it pushes warm air up. High temperatures Saturday should reach into the mid-50s despite rain and clouds.

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GFS model output for overnight Friday into Saturday

Sunday – rain should end overnight Saturday, and high pressure from Canada should quickly build in behind this storm system. The positioning of this high pressure, along with the exiting low, will make for a tight pressure gradient, which should allow for stiff northwest winds perhaps in the 15-25mph range. Temperatures will drop back into the low 40s with the arrival the colder Canadian air.

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GFS model output for Sunday night

Monday – the storm system from Saturday will move offshore, but it appears from model runs that there’s some chance the storm lingers. As the high pressure from Sunday moves off to the northeast, the clockwise flow behind it may draw this offshore area of low pressure back into the area. This could lead to some rain on Monday. It’ll be a mostly cloudy day otherwise with highs in the low 40s.

Pacific Storm Slams California

Earlier this week, California got slammed by a very strong Pacific low. This storm brought on furious rains that dropped 1″+ in many areas of Northern California, with totals as high as 3-4″ in spots near the Coast Range and Sierra, as well as further south in the mountains east of San Diego. These totals represent more rainfall than had fallen in many of these areas all of last year.

You can see from the map below which overlays drought conditions (the deeper the red, the more extreme the drought, with the darkest red representing extreme/record-breaking drought) with rainfall totals from yesterday. You’ll see that much of the heaviest rain did fall over regions worst affected by drought. Sadly, though this is a case of too much of a good thing, as much of this desperately needed rainfall occurred so quickly, it will simply runoff back into the ocean.

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Map of California with drought condition layer (reds/oranges), and rainfall totals from yesterday

NYC Weather – Pre-Thanksgiving Storm Back On

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It’s hard to believe now, with air temperatures still hovering around 60 at this hour on Monday, that by Wednesday, our entire region could be looking at accumulating snow! Over the weekend, it has become clear through progressive model runs that the mid-week storm that on Friday looked like it would miss us, is tracking to hit us on Wednesday, leading to a high impact storm just in time for the busiest travel day of the year. We’re talking the whole package: wind, rain, and snow.

Tuesday – we continue to stay in the warm sector of a low pressure system that will be exiting to our northeast through Quebec. Cloud cover will be minimal and we should see temperatures hold around the 60 degree mark.

Wednesday – a complex weather situation develops as a coastal low that forms offshore of the Georgia/Florida border Tuesday makes its way up the Northeast coast. Temperature profiles seem to be pointing towards a mostly snow event (the first big snow storm for the region). With the cold front pushing through late Tuesday, temperatures Wednesday will likely peak in the morning around 40 and start to drop slowly through the day as precipitation moves in across the area, generally from southwest to northeast. Wind will start to pick up, first from the southeast, then east and gradually becoming northeast between 25-35mph.nam-hires_namer_048_1000_850_thick

The tricky part about this forecast is that there is still enough uncertainty in the storm track for there to be some last minute changes. As it currently stands, the center of the strengthening coast low is forecast to move on top of or just west of the 40ºN 70ºW benchmark, a scenario that favors a high-impact nor’easter type event for our region. Winter storm watches are already up over much of the interior Northeast. In these areas, we are looking at anywhere from 4-10″+ (depending on where the heaviest band sets up). Along the coast, under the current forecast track and methodology, it is looking like enough rain mixes in during the day Wednesday to keep snow accumulations from topping 5-6″.

Again the storm track could change, and if the track moves slightly to the east, the heavier snow could hit the city, along with some colder air. Regardless, this does not bode well for people who are doing last-minute traveling for Thanksgiving. I would expect widespread flight delays, while traffic conditions on the road could deteriorate quickly especially later in the day with temperatures dropping and snow beginning to stick.

Thursday – Thanksgiving Day itself looks like it will be OK for the parade, and other activities. The coastal storm will have pulled to our northeast, and any lingering effects should clear up early. Temperatures will be around the 40 degree mark in the city, which means that snow which accumulates will not melt all that quickly.

Friday – will be the coldest day of the holiday stretch, with temperatures only in the mid-30s. Areas of snow that have melted during Thursday could re-freeze.

The remainder of the holiday weekend looks good so far, with no major precipitation anticipated until Sunday/Monday.

 

 

 

 

 

 

Stunning Satellite Images – Lake Effect Snow

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In my previous post, I discussed the ongoing epic and record breaking lake effect snowstorm that’s absolutely pummeled areas of the Great Lakes snowbelts, with the Tug Hill Plateau area south of Buffalo the worst affected. Snowfall totals yesterday were already approaching 6 feet, and this morning, the snow continues to pile up. Check out this series of satellite images and accompanying analysis. These images are simply stunning in how clearly they demonstrate the powerful effects of lake effect snow.

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Satellite image of the Great Lakes captured by Geostationary Operational Environmental Satellite. You can clearly see bands of lake effect snow streaming across the entire region.

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Weather Prediction Center’s analysis of current surface conditions – note the low pressure center over extreme NE Ontario/SW Quebec

A close up of Lakes Erie and Ontario – luckily for these folks, winds will finally begin shifting tomorrow as that low pulls away and winds shift from ideal direction for long fetches across the lakes to the northwest.

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NYC Weekend Weather – Return of the Polar Vortex? – Jul 11, 2014

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You may have heard from media reports that the dreaded polar vortex is set to make a return to the Eastern US during the middle of the coming week. I’ll discuss that in detail below. First, for the weekend forecast:

Today & Saturday – a very pleasant couple of days in the wake of the cold front that finally pushed through our area yesterday. You can feel a marked drop in humidity, and temperatures are much more comfortable. Saturday, high temperatures should top out in the mid 80s in NYC.

Sunday – a chance for afternoon thunderstorms and a high in the mid 80s, chance of rain increasing through out the day into the overnight hours.

Polar Vortex?

Forecast models are in good agreement that beginning Tuesday into most of the rest of next week, an upper air vortex (see below, the trough with an inclosed region surrounded by the blue arrows) will drop into the Midwest and Northeast from the northern regions of Canada. This vortex can be technically referred to as a polar vortex, a term that instantly revives media hype about how cold it will be. But keep in mind, during the summer, polar regions heat up as well, so even the coldest polar airmass and vortexes are much milder than their winter counterparts. Furthermore, the influence of the sun is quite strong as we just passed the summer solstice, so the sun is sitting at a very high angle each day and is highly effective at heating the air quickly. Hence, temperatures are expected to be much below normal for some areas, but we’re not talking about snow or ice.

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Upper air forecast from GFS for Monday, 8PM EDT, 500mb absolute vorticity.

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Next Week

There will be a good deal of energy traveling with the polar vortex, so we’re expecting a somewhat disturbed pattern of weather for the beginning of next week. Tuesday & Wednesday will see the best chances for rain and thunderstorms with a cold front approaching us from the west. Before the cold front, we’ll still see temperatures in the mid to upper 80s with a chance for thunderstorms Monday. Once the cold front passes, we’ll be right in the mix with the “polar” air mass, so our high temperatures will drop into the low 80s, and overnight lows will drop into the upper 60s for the latter part of the week.
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