Tag Archives: high pressure

NYC Weather Update – Feb 18, 2020

NYC, Rain, Weather Update, , , , , ,

Cloudy day with light rain possible to start the forecast period. Skies clear for the remainder of the week behind this storm as high pressure builds. Temperatures will dip into the 30s for a brief stretch as well before rebounding back to above normal levels in the mid to upper-40s. Looking ahead into next week, above normal temperature trend is very likely to continue.

Rest of today – Light rain possible today with a warm front passing nearby and a cold front following behind that. However, the bulk of the moisture with this storm system appears to be focused south of the region, so not expecting any heavy rainfall totals. Otherwise, mostly cloudy with highs in the upper-40s. Overnight lows around 40°F with gradual clearing towards daybreak.

Weather Prediction Center surface forecast for 7PM Tuesday.

Wednesday – mostly sunny with high temperatures in the low-40s, about average for this time of year. Winds turn to the northwest behind the cold front, which will facilitate cold air advection. Overnight lows in the mid-20s as a result with high pressure building.

Thursday – cold start to the day will likewise mean a cooler high temperature in the mid-30s with mostly sunny skies. High pressure continues to exert its influence. Overnight lows once again quite cold in the low-20s.

Climate Prediction Center temperature outlook for Feb 23-27, showing greater than 90% probability of above normal temperatures for much of the Northeast.

Friday – this pattern continues with high temperatures Friday reaching into the mid-30s under mostly sunny skies. Overnight Friday into Saturday, the high pressure finally starts moving east in earnest. Lows will range in the upper-20s.

NYC Weather Update – Feb 11, 2020

NYC, Rain, Snow, Weather Update, , , , , ,

Light rain today will fall today. This will be followed by a brief spell of sunny skies and calm weather Wednesday. Another storm system impacts the area Thursday, bringing some mixed precipitation and rain. On the back side of this system, a drastic drop in temperatures will take place going into the weekend. This will be the coldest air mass we’ve seen in many weeks with lows in the teens.

Rest of today – Light rain in the morning and cloudy. High temperatures in the upper-40s. Overnight lows in the mid-30s with gradual clearing.

Weather Prediction Center surface forecast for 7AM Wednesday

Wednesday – high pressure briefly builds in with high temperatures in the mid-40s. Mixed precipitation could begin later in the day as the next storm system approaches. Overnight lows in the upper-30s with increasing mixed precipitation then transitions to rain.

Thursday – A warm up takes place with a warm front and southerly flow overnight. High temperatures reach into the mid-50s with rain ending in the morning/early afternoon. Much cooler temperatures overnight with lows around 30°F once the cold front of this storm system moves through.

GFS model 1000-500 mb precipitation and thickness valid 5PM Friday. Note the large area of Canadian high pressure centered over Indiana.

Friday – strong Canadian high pressure builds behind the cold front mentioned above. A much colder air mass will accompany this high, with temperatures Friday only in the low-30s. The real chill takes place overnight, with lows dropping into the mid-teens as Arctic air keeps pumping in!

NYC Weekend Weather – Feb 7, 2020

NYC, Rain, Storms, Weather Update, Weekend, , , , , , , ,

We start this weekend with a high wind warning as a strong low pressure center passing overhead. A much colder air mass will be on the heels of this passing storm. A brief calm Saturday spell punctuates an otherwise active pattern with another storm approaching to start next week. High temperatures during this time will generally be at or above normal (~40°F) with a big warmup by Monday.

Rest of today – high temperatures have already peaked in the mid-50s but the remainder of the day will see a continuing fall in temperatures through the 40s and 30s as strong cold air advection kicks in. This is due to a potent low pressure system (972 mb and strengthening) passing overhead. The tight pressure gradient around this low, in addition to a well-mixed layer forming with winds aloft at 50 knots mixing down will yield very strong winds. A high wind warning is in effect this afternoon when sustained winds could easily be in the 30-40 mph range with gusts exceeding 60 mph in places. Winds will abate overnight as the low exits northeast, temperatures will keep falling all the way into the upper-20s with cold air advection driven by winds from the northwest continuing.

  • Weather Prediction Center surface forecast for 1 PM today. Note the tight packing of isobars around the 972 mb low pressure center moving just north of the area.
  • NAM model’s forecast sounding for 1PM today. Very strong unidirectional wind profile is indicated, with winds just above the surface in excess of 50 knots. A well-mixed layer is evident as well up to about 850 mb where winds look to range between 55-65 knots. This should allow strong gusts and sustained winds to make it to the surface.

Saturday – high pressure builds in briefly, and should yield a mostly sunny day. With overnight lows in the upper-20s, high temperatures will be decidedly colder around 40°F. Overnight lows remain on the cold side around 30°F.

Sunday – clouds increase with high temperatures in low-40s as the next frontal system approaches. Winds will shift to the south. There is a chance for rain/snow mix then rain during the day. Overnight lows in the mid-30s.

Monday – prolonged southerly flow will help kick temperatures up to the low-50s as the frontal system slows in its approach. This will also bring prolonged chances for rain. Overnight lows in the upper-30s.

NYC Weekend Weather – Jan 31, 2020

NYC, Rain, Weather Update, Weekend, , , , , , , ,

Rain to start this weekend leads to a dramatic pattern change with anomalous ridging taking place by late in the forecast period. Temperatures throughout the period range from a few degrees above normal in the mid-40s to the mid-50s by Monday. The warmth continues into the middle of next week.

Rest of today – mostly cloudy with high temperatures in the mid-40s. A relatively weak coastal low will develop and move towards our area overnight. The best chances for rain are in the early overnight hours. Overnight lows in the mid-30s.

Saturday – rain chances will diminish quite a bit as the core of the low continues exiting to the northeast. Mostly cloudy with high temperatures in the mid-40s. Overnight lows in the the mid-30s. Some snow could mix in overnight as lingering chances for precipitation continue.

Sunday – things will dry out as the low continues to distance itself from us. Mostly sunny with high temperatures in the mid-40s. Overnight lows in the upper-30s.

Monday – the synoptic scale pattern shifts as strong ridging at the mid-levels occurs. This will translate to warm high temperatures in the mid-50s on Monday with mostly sunny skies and southerly flow. Overnight lows in the mid-40s.

NYC Weekend Weather – Jan 16, 2020

NYC, Rain, Snow, Weather Update, Weekend, , , , , , ,

This weekend coming up will see a dramatic contrast from last weekend’s record-breaking warmth. Temperatures during the next few days will be average to below normal. Overnight lows in the low-20s for this period. A “warm up” will happen as we enter the warm sector of a passing storm Saturday going into Sunday, but reinforcing cold air arrives to start next week.

Rest of today – partly sunny with strong northwesterly winds. Temperatures will drop from around 50ºF into the low in the mid-20s overnight. A trough extending west from a departing area of low pressure that’s bringing the strong winds may touch off some rain.

Friday – a cold, sunny day with high temperatures starting off in the low-20s and only expected to reach 30ºF under the continuing influence of northwesterly winds .

Saturday – a large storm system will move through. Temperatures starting off in the low-20s will warm into the upper-30s with southerly flow ahead of the main cold front associated with this low. Thermal profiles will support snow to start, with a light accumulation possible before temperatures warm enough at the coast to transition to all rain overnight. Overnight lows aren’t expected to move much, dropping into the mid-30s.

  • GFS model 500 mb height anomalies for 7AM Monday
  • GFS model 300 mb heights and winds for 7AM Monday – the orientation of the jets stream mirrors the position of 500 mb height anomalies

Sunday – improving conditions with high temperatures in the upper-30s and partly cloudy skies. Overnight lows in the low-20s as a second and stronger blast of Arctic air flows in behind Saturday’s storm.

NYC Weekend Weather – Jan 10, 2020

Climate, NYC, Rain, Weather Update, Weekend, , , , , , , ,

The weather story for this weekend in NYC will be the near record-breaking warmth we’ll have with temps at or above 60°F Saturday and Sunday. A storm system sweeps through overnight going into Sunday, and should clear by Sunday afternoon. Behind this, temperatures will drop back to the upper-40s, which is still almost 10ºF above normal for this time of the year! Enjoy this rare occurrence of near record warmth that isn’t accompanied by a washout.

Rest of today – mostly cloudy with high temperatures in the low-50s. A strong area of high pressure offshore southeast of our area will be steadily pumping warm, moist air into the region. Looking at the chart below, you’ll see southerly winds blowing at large angles across temperature contours that increase going south – this is an ideal set up for persistent warm air advection and will set the stage for the warmth we see this weekend. Overnight lows in the mid-40s. With moisture advecting into the area, we could see areas of fog develop overnight.

GFS 2-meter temperature with contours and 10-meter wind barbs.

Saturday – very mild with temperatures in the low-60s. Mostly cloudy with a southerly breeze and some fog possible. Overnight lows in the mid-50s. Rain chances increase particularly late overnight going into Sunday morning.

Sunday – elevated convection could bring a rumble of thunder Sunday morning, with rain chances peaking in the early morning hours. High temperatures should remain quite mild, in the mid-60s (and possibly higher with downsloping westerly winds for a period with clearing skies, following the passage of a prefrontal trough and before a cold front closes in). Overnight lows dropping into the low-40s – which is actually still above normal for what a daytime high temperature should be this time of year.

NAM high resolution model output of 1000-500 mb thickness, surface pressure, and precipitation valid for 5AM Sunday

Monday – high temperatures similar to Friday near 50ºF, partly sunny skies. Overnight lows in the low-30s.

NYC Weather Update – Jan 7, 2020

NYC, Rain, Snow, Weather Update, , , , , , ,

A quick hitting storm system brings possible light snow to the region overnight into Wednesday. High pressure builds behind this storm, with winds shifting to the northwest bringing a cool down midweek. Another storm approaches towards the end of the week. Ahead of this, temperatures surge back above normal, approaching 60°F, as southwesterly winds instigate warm air advection.

Rest of today – increasing clouds with high temperatures in the mid-40s. A coastal low passes east of the area, bringing some potential for light snow accumulations (1″ or so). Precipitation will start off as rain, though, then transition to snow briefly overnight. Overnight lows drop to around 30°F.

Weather Prediction Center surface forecast for 7PM Tuesday

Wednesday – snowfall may be enhanced by a second fast-moving arctic front. Behind this front, high pressure builds. Decreasing clouds, with winds picking up from the west then veering northwest towards overnight hours. High temperatures in the low-40s. Overnight lows will plummet quickly into the upper-20s with an Arctic air mass and northwesterly flow. Winds may gust above 30 mph during the overnight hours.

Thursday – expecting a calm, bright, sunny day with high temperatures in the low-30s, below normal for this time of year. High pressure will be moving right over us during this time. Overnight lows in the low-30s.

GFS model 500 mb height anomalies for 1AM Friday. Note the strong positive height anomaly over the Northeast, with a corresponding strong negative height anomaly over the Rockies.

Friday – high pressure will move offshore to the east, setting up warm southwesterly return flow between the western periphery of the high and an incoming storm system. High temperatures expected in the upper-40s. Temperatures should in fact warm up overnight, through the upper-40s.

NYC Weekend Weather – Dec 20, 2019

NYC, Weather Update, Weekend, , , , ,

We’ll enjoy a prolonged period of calm weather that should take us through the week of Christmas. Temperatures should warm from below average in the 30s to above average near 50°F by the start of next week. The above average temperature trend looks like it will extend through the week. No white Christmas this year. I’ll be taking some time off and won’t have another update until closer to the new year unless something significant shapes up.

Rest of today – clear conditions with high temperatures already peaking around the low-30s. Overnight lows in the low-20s with an Arctic air mass still hanging around.

Weather Prediction Center surface forecast for 7AM Saturday

Saturday – the high pressure responsible for the cold, but calm and sunny conditions progresses east and return flow should start taking hold, with winds veering south later in the day. High temperatures should be similar to today in the low-30s. Overnight lows will be warmer than tonight in the upper-20s with milder westerly downsloping flow.

Sunday – high temperatures continue to climb into the mid-40s as more southwesterly flow takes hold. Overnight lows likewise continue a warming trend to about the freezing mark.

  • GFS model output for 500 mb vorticity, wind and heights valid 6AM Tuesday, showing a flat, zonal flow set up
  • Climate Prediction Center temperature outlook for December 25-29, calling for warmer than average temps over much of the Eastern US.

Monday – the warming continues with high temperatures forecast in the upper-40s to near 50°F. Overnight lows in the mid-30s.

Next week, it appears that we’ll be in a mostly zonal (flat westerly flow) regime at the upper-levels. That should help keep things calm and uneventful.

NYC Weather Update – Dec 17, 2019

NYC, Rain, Snow, Weather Update, , , , , , , ,

A soggy and messy start to the week will give way to a blast of Arctic air, leading to an extended period of below normal high temperatures only in the 30s for the most part. Temperatures do look to rebound over the weekend towards more seasonable levels. The next chance for precipitation happens Wednesday as an arctic front, harbinger of these much colder temperatures, crosses the area and brings possible snow squalls.

Rest of today – periods of rain during the day with high temperatures in the mid-30s. Rain tapers off and ends early this evening as the low pressure responsible for the stormy conditions moves off to the east. Overnight lows drop to around 30°F.

GFS model 500 mb height anomalies for Wednesday at 7PM, note the strong negative height anomaly over the Northeastern US and St. Lawrence Valley

Wednesday – should be a mostly sunny day, though as an arctic front hits us late in the day and in the early evening, a few snow squalls/snow bands could hit. These would be brief in nature but could impinge on visibility, making travel difficult. High temperatures should be similar to today in the mid-30s. Overnight lows will plummet quickly into the upper-teens with an Arctic air mass and northwesterly flow.

Thursday – northwesterly flow continues as strong Arctic high pressure builds. This will keep temperatures only in the upper-20s for highs under mostly sunny skies. Overnight lows in the low-20s.

Weather Prediction Center surface forecast for 7AM Friday

Friday – temperatures moderate a little bit, with highs in the low-30s as the high starts moving east. Overnight lows in the low-20s.

NYC Weather Update – Dec 10, 2019

NYC, Weather Update, , , , , ,

Very mild air at the start of the week gives way to a much colder air mass as a cold front finally sweeps through later today. Drenching rains from yesterday should give way to lighter precipitation today, however, with temperatures dropping we could see some light accumulating snow by Wednesday morning. Temperatures will rebound into normal to above normal ranges after a dip into high temperatures in the 30s mid-week.

Rest of today – mostly cloudy with high temperatures peaking in the upper-50s. Long duration southerly flow ahead of an slow moving cold front has brought in a much warmer air mass to the region. Rain chances pick up in the afternoon with the front nearing and continues into the overnight hours with a couple breaks. Behind this front, much colder air rushes in with overnight lows dropping to near freezing. With precipitation continuing, this should allow for a transition to all snow. Light accumulation of around 1″ is possible, though not a lock since the ground has been quite warm for a couple days now with all the rain.

Weather Prediction Center probabilistic forecast for 1″+ accumulation of snow by 7AM Wednesday

Wednesday – snow winding down in the morning. High temperatures in the upper-30s, about 10°F below normal for this time of year. Skies clearing later in the day with overnight lows in the mid-20s.

Thursday – with a chilly start to the day, high temperatures will have a tough time getting out of the low-30s. Mostly sunny otherwise. Overnight lows in the upper-20s.

Friday – high pressure that fills in behind the cold front passing Tuesday and giving us the sunny weather Thursday eventually moves off to the northeast. Onshore flow should help moderate highs into the upper-40s. Rain chances increase with the next storm system – a possible coastal low – moving up overnight. Overnight lows in the mid-40s.