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NYC Weekend Weather (Brooklyn Half Marathon) – May 14, 2015

Rain, Thunderstorms, Weather Update, Weekend, , , , , , , , , , ,

This week ends off with pleasant, sunny, dry weather, and temperatures slightly above average in the low 70s. We get a chance at some much needed rain (there were actually brush fires yesterday, giving you an idea how dry it’s been), but the unfortunate part is that the rain will likely occur in periods on Saturday. Sunday will be better, as it doesn’t look like the rain sticks around that long.

Rest of today – a gorgeous spring day with high pressure in control, yielding a cloud-free and seasonable day with highs in the low 70s.

High pressure firmly entrenched over us today and tomorrow.
High pressure firmly entrenched over the region today and tomorrow.

Friday – expecting more of the same during the day, mostly sunny and mild with temperatures topping out again in the low 70s. Later Friday night, there could be a few showers and thunderstorms that develop as an approaching frontal system nears the area.

Saturday – lingering showers and maybe a thunderstorm or two in the morning, but it does not appear the entire day will be a washout. We’ll be in the warm sector which should allow for temperatures to approach 80 or slightly higher, depending on the cloud cover situation in the afternoon hours. Sadly, I know this is not what all you runners that are going to be doing the Brooklyn Half Marathon want to hear.

North American Model high resolution output for Saturday at 11AM, showing the possibility of showers.
North American Model high resolution output for Saturday at 11AM, showing the possibility of showers.

Sunday – at this point, it appears Sunday will be dry, with more clouds than sun, and temperatures remaining warm in the upper-70s. A blocking high pressure center over the Gulf of Maine should be enough to prevent rain from entering the area. gfs_namer_108_1000_850_thick

Monday – the high pressure depicted above will retreat eastward a bit, which would allow for a better chance of rain later Monday evening/night into Tuesday. During the day, conditions should be dry with partly sunny skies and a high near 70.

NYC Weekend Weather Update – May 16, 2014

Flooding, NYC, Rain, Thunderstorms, Weather Update, Weekend, , , , , , , , , , ,

First for weather headline that will be dominating today: the storm system that is set to bring us heavy, potentially flooding rain later today and into the overnight hours. Currently, temperatures in our area are generally in the mid-upper 60s with a strong south to southeasterly wind. This is leading to an influx deep moisture ahead of the approaching cold front. We are firmly entrenched in what meteorologists refer to as a warm sector. This will provide the necessary conditions for heavy rain and some possible embedded thunderstorms to form later.

NOAA NCEP surface analysis as of 9AM EDT. Note the cold front sitting just off to our west with an elongated area of moderate to heavy rain.
NOAA NCEP surface analysis as of 9AM EDT. Note the cold front sitting just off to our west with an elongated area of moderate to heavy rain.

Based on the latest output from GFS and NAM models, it would appear the heaviest of the rain will arrive in our area during the PM rush and last through the evening into the early morning hours. So, if you’re going to be heading out this evening, grab an umbrella and appropriate rain gear.

NCEP's forecast for quantitative precipitation totals over the next 24 hours.
NCEP’s forecast for quantitative precipitation totals over the next 24 hours.

One of the major hazards with this storm is flash flooding and flooding in general. Because a high amount of precipitation is anticipated to fall in a relatively short time window, flash flooding is a real concern especially in urban areas and small streams. This will make for a sloppy and slow evening commute. The flip side of the fast moving nature of this storm system is that it should clear the area fairly quickly, meaning that you runners out there should have slightly better conditions than previously forecast for the start and duration of the Brooklyn Half Marathon.

NAM high resolution model output showing the cold front and storm system to have pushed through our area by about 5AM EDT
NAM high resolution model output showing the cold front and storm system to have pushed through our area by about 5AM EDT

Saturday after the cold front passes through and the rains subside, we should be looking at gradually clearing skies and slightly above average temperatures in the low 70s.

Sunday through Tuesday – we will be compensated for this rainy Friday by a string of days with fair conditions and seasonable temperatures. A high pressure center will form and camp out over our area, preventing any bad weather from impacting us. As such, temperatures should be nearly steady each day during this period in the upper 60s to low 70s with mostly sunny skies.

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NYC Weather Update & BK Half Marathon – May 14, 2014

Flooding, NYC, Rain, Storms, Thunderstorms, Weather Update, Weekend, , , , , , , , , , , ,

We’ve been fortunate that a persistent high pressure off of Nova Scotia has been stalling the arrive of a storm system earlier forecast to bring showers during the midweek period.

Our luck is about to run out, however, as the low pressure center and associated frontal boundaries will finally make their approach over the NYC area.

Thursday – overnight, a warm front is projected to pass through our area, bringing along a chance of drizzle, and the possibility for dense fog tomorrow morning as lower levels of the atmosphere become saturated with the coming southerly flow. Once the warm front passes over us, we will see a noticeable increase in temperatures, with highs forecast to be in the mid-upper 70s and possibly low 80s in interior portions of the region. Although the probability is low, there could be a couple showers and stray thunderstorms as well.

Friday – as the cold front associated with the low pressure center below draws closer, chance of precipitation will increase steadily during the course of the day. To start off, lighter showery precipitation should move in during the morning and early afternoon hours. Thereafter, heavier precipitation, and possibly thunderstorms, will move in especially during the evening and overnight hours. Due to the ground being somewhat saturated from the last round of rain we got, there could be some flash flooding in the heaviest down pours. Temperatures will be a bit cooler than Thursday in the upper 60s to around 70.

L and H correspond to approximate locations of surface low and high pressure centers. Notice the strength (high amplitude) of the associated upper trough and ridge
L and H correspond to approximate locations of surface low and high pressure centers. Notice the strength (high amplitude) of the associated upper trough and ridge

Saturday (BK Half Marathon Race Day) – good news for you runners out there as it appears the weather will cooperate for race day. The pesky slow-moving frontal boundary responsible for the rain on Friday will finally clear the area early Saturday morning, just in time for the start of the race. There may be some light showers early, but once the front clears conditions should start to improve. I would estimate start time temperature to be in the low 60s, with a high temperature forecast to be in the low 70s.

Simulated radar image from the North American Model (NAM)
Simulated radar image from the North American Model (NAM) for Saturday at 8AM EDT

Sunday – a return to nice weather as the cold front has passed through and high pressure builds in temporarily. Partly cloudy with a high in the low 70s.