Tag Archives: prefrontal trough

NYC Weekend Weather – Jun 26, 2020

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A warm and potentially stormy start to the weekend on tap with Storm Prediction Center placing the area under slight risk for severe weather Saturday. Temperatures during this period in the upper-80s. Weather improves on Sunday behind a cold front. Next week, a lingering upper low may bring daily chances for rain in the afternoons.

This afternoon – mostly sunny with a high in the mid-80s. Overnight lows in the low-70s with increasing clouds towards daybreak.

  • Weather Prediction Center surface forecast for 8PM Saturday
  • Storm Prediction Center convective outlook for Saturday, showing the region under slight risk for severe weather.

Saturday – a warm front pushes through early in the morning and some showers could accompany this. Mostly cloudy with high temperatures in the upper-80s. A cold front is forecast to push through later, with a prefrontal trough ahead of it. These will serve as the loci for more organized convective activity. Thunderstorms forming in the warm sector behind the early warm front passage may be able to attain severe limits. The main threat is from damaging winds. Overnight lows in the mid-70s with rain chances diminishing early.

Sunday – despite the cold front passage, temperatures stay largely similar to Saturday in the upper-80s due to downsloping winds from the west. With an upper low lingering, isolated, diurnally driven thunderstorms may pop up in the late afternoon, mostly sunny otherwise. Overnight lows in the low-70s.

Monday – mostly sunny though a chance for afternoon pop up showers or thunderstorms persists. High temperatures remain warm in the upper-80s. Overnight lows in the low-70s. Below, you’ll see GFS forecasts for this upper low continuing to influence our weather going into next week. The tangible impacts for this will be continued chances of scattered showers and thunderstorms for much of the week until this upper low finally gets picked back up by primary westerly steering currents and moves offshore.

GFS model 500 mb height and wind. You can see evidence of a persistent upper low that drifts south, then gets cutoff from main steering currents, and remains largely stationary, even retrograding west during next week over the Northeast.

NYC Weekend Weather – Jan 31, 2020

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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 10, 2020

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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.