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Weather While Traveling in Mexico – Feb 25, 2019

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In lieu of an early week forecast this week, I’m opting to share some observations about weather I experienced in Mexico last week while on vacation. I stayed in Isla Mujeres, a small island located about 13 miles off the coast of Cancun. Temperatures were of course quite warm. It was also unusually windy for this time of year down there, though nothing quite like the windy weather NYC experienced today with some peak winds recorded at over 50 mph nearing 60 mph.

KJFK 250551Z 27022G38KT 10SM FEW070 06/M05 A2953 RMK AO2 PK WND 27049/0504 SLP998 T00611050 10083 20061 53017 $

KLGA 251351Z 28020G42KT 10SM SCT065 03/M11 A2970 RMK AO2 PK WND 27050/1331 SLP058 VIRGA W-N T00281106 $

METAR READINGS FROM JFK and LGA showing peak winds of 56 mph and 58 mph respectively recorded at 12:04AM and 8:31AM respectively todaY

I’m only just getting adjusted back to cold temperatures, and am not looking forward to snow possibly falling Wednesday night and another storm bringing wintry precipitation Friday. On the bright side, we are now only about 3 weeks off from the vernal equinox and the start of spring!

On the Servicio Meteorológico Nacional (SMN) – National Meterological Service of Mexico

Since I was going to be in Mexico, I started checking out the Mexican government’s weather service page. Check out the surface analysis below that’s overlaid on what looks like a GOES East image from last Thursday (02/21/2019).

Click to enlarge this surface analysis from the Mexican SMN

Unlike our own National Weather Service, the SMN numbers frontal systems that move through Mexico. Notice the stationary front in the center of the image is labeled as “Frente No. 38” (Front #38) and you can see “Frente Frio No. 40” (Cold Front #40) crossing from southern California into northern Baja California in the upper left corner of the image. They also number their winter storms. The “B” (representing a low pressure center) over Nevada is labeled as “Octava Tormenta Invernal” (Eighth Winter Storm). “Corriente en Chorro Polar” (polar jet stream), “Corriente en Chorro Subtropical” (subtropical jet stream) are familiar features to us, which we seen streaking across the northwest and central portions of Mexico respectively. A “Corriente de Bajo Nivel” (low-level jet) is seen flowing from the east towards the Yucatan. Here’s a translation of the text in the lower left panel:

Systems affecting Mexico
The Eighth Winter Storm over the southwestern US combined with cold front #40 in northwestern Mexico will favor showers with some strong storms, very cold temperatures, and wind gusts over 60 km/h in the northwest and northern Republic, and also the potential for snow or sleet in mountainous areas of Baja California, Sonora, and Chihuahua, extending gradually towards Durango. Front #38 with stationary characteristics extends over the western Gulf of Mexico and will generate clouds with isolated rain in the eastern and northeastern parts of the country.

Servicio Meteorológico Nacional of mexico

Synotpic Conditions – the Tropical Big Picture

The consistent breezy south-southeasterly winds I felt on Isla Mujeres were tied to that low-level jet (LLJ) pictured above. This LLJ enhanced the general easterly trade winds in the area. This was a result of the influence of a high anchored over the Western Atlantic, and a low over northern Colombia pictured in the OPC surface analysis below (issued Friday 2/22 02:35Z) “funneling” the winds.

In this analysis of the Western Atlantic from NOAA’s Ocean Prediction Center, you can see that a broad high pressure center was anchored near Bermuda. Meanwhile, a low sat over northern Colombia. The clockwise flow around the high and counterclockwise flow around the low in proximity to each other act to enhance the easterly trade winds found in the tropics.

A sounding from Philip Goldson International Airport near Belize City (the closest sounding station I could find to Cancun) showed clear evidence of a well-mixed layer from the surface to just about 900 mb. It felt like in Cancun, this mixed layer extended a bit further up into the 850 mb level where the LLJ sat because the winds were stronger.

Sounding taken above Philip Goldson International Airport near Belize City at 7PM Feb. 20, 2019, showing a well-mixed boundary layer representative of the area around the Yucatan Peninsula during these few days

By way of brief explanation, well-mixed layers like the one shown above provide favorable conditions for faster moving winds aloft to transfer their momemtum downwards, in this case all the way to the surface. It shouldn’t be a surprise that a deep well-mixed layer also existed today over NYC – enabling the strong winds aloft to mix down, leading to some very strong winds and gusts.

Sounding from Upton, NY for at 7AM Feb. 25, 2019, showing a deep well-mixed layer down to the surface from around 800 mb with strong winds 35-50 knots through most of this layer

Aside from the winds, the weather followed a pretty standard tropical pattern with clouds building in the afternoon and isolated showers. Despite how flat the Yucatan Peninusla is, it nevertheless provides at least some small potential for lift and convergence for air flowing off the Caribbean Sea. This is because there’s actually a significant difference in frictional properties of land and water, which makes sense since the surface of the ocean is considerably “smoother” than the corresponding forested Yucatan. One other notable trait was that the base of rain clouds in the area took on a distinctively blue hue, which I imagine was a reflection of the characteristically blue waters of the Caribbean Sea.

NYC Weather Update – Jan 21, 2019

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What ended up being a rain storm for NYC yesterday has brought along the coldest air of the year in its wake. The bitter Arctic chill won’t last long, with temperatures on an upwards trend through the mid-week period as another storm approaches. By Thursday, temperatures in the upper-40s will feel like summer compared to the frigid start today. Beyond that, temperatures look to cool off again into next weekend, but it appears to be a dry weekend ahead.

Rest of today (MLK Jr. Day) – overnight lows in the city were in the single digits, and despite lots of sun, the Arctic high in control over the area will limit any significant warming. High temperatures are expected to be in the mid-teens with blustery northwest winds making wind chills feel below zero. Overnight lows dip back into the low-teens, but winds should abate somewhat as the core of the Arctic high moves closer to us and the pressure gradient relaxes.

Tuesday – much warmer than today, by about double, but still cold with high temperatures in the upper-20s. Sunny skies expected with high pressure still in control. Not much change in temperatures overnight into Wednesday as the next storm system brings a warm front to the area.

Weather Prediction Center surface forecast valid 7AM Wednesday

Wednesday – temperatures in the low-40s as we get in the warm sector of an approaching low centered over the Great Lakes. Temperature profiles should support all rain, though there could be some mixing early Wednesday as precipitation starts. Overnight lows again don’t budge much. More rain is expected going into Thursday.

Thursday – long duration rain event continues, with temperatures in the upper-40s and mostly cloudy skies when it’s not raining.

NYC Weekend Weather – Sept 7, 2018

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Cooler temperatures are finally upon us after a very hot and humid week. However, the cooler weather also brings a prolonged period of cloudy conditions, with chances for showers each day this weekend. Rain chances continue into the beginning of next week with a storm system approaching. Long-term, we look towards the tropics, as Tropical Storm Florence continues to have the potential for bringing some impacts to the area.

Rest of today – overcast, with much cooler high temperatures in the mid-70s. Chances for showers, especially later in the day.

Saturday – cloudy with high temperatures remain cool in the low-mid 70s with northeasterly onshore flow behind a cold front draped west-east south of us. This front (which passed through yesterday) will become stationary. Multiple impulses of energy will run along this boundary and allow for continued slight chances of showers.

Sunday – yet another cool, cloudy day with chances for rain. High temperatures around 70°F.

Monday – the stationary front stalled out south of us will return north as a warm front. As this happens, chances for rain increase, along with temperatures rising back into the mid-upper 70s.

Will Tropical Storm Florence Impact the East Coast?

Tropical Storm Florence has been active over the eastern and central North Atlantic for over a week now. Within the last few days, Florence underwent a rapid intensification that brought it up to Category 3 status, making it the first major hurricane of the 2018 Atlantic hurricane season. Subsequently, it has weakened to a tropical storm under relentless strong shear. However, it is expected to reintensify into a major hurricane once shear subsides. Worrying trends in the track forecast for Florence continue to allow for the possibility of landfall on the East Coast, or at the very least, substantial coastal impacts like dangerous surf and beach erosion. However, the National Hurricane Center continues to note that there is considerable uncertainty to the track forecast for Florence, such that it is still too early to determine what effects it will have on the East Coast. This storm will warrant careful observation over the coming days and I will have subsequent updates on it.

NYC Weather Update – Sep 4, 2018

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A brief break in the heat over the weekend has led back into another warm spell to begin this week. This latest blast of heat will be short-lived as a backdoor cold front sweeps through tomorrow, followed by another, stronger cold front later this week. Temperatures for the upcoming weekend will once again be comfortable, seasonable to below average. In the tropics, things are starting to get busy with tropical storms Florence and Gordon active and another tropical wave poised to become a tropical cyclone off the coast of Africa. Gordon will make landfall overnight on the Gulf Coast east of New Orleans.

Rest of today – hot and humid with temperatures in the low-90s, mostly sunny skies.

Wednesday – cooler, though still warm with high temperatures in the upper-80s and partly sunny skies. A backdoor cold front will bring cooling onshore southeasterly breezes that help keep a lid on temperatures.

Thursday – temperatures rise back a couple degrees into the low-90s ahead of an approaching cold front from the northwest. The warm air ahead of the cold front could help set the stage for a few scattered strong thunderstorms as the front passes through.

Friday – temperatures cool off quite a bit into the low-80s under mostly cloudy skies. Chance of showers during the day with the cold front lingering south of the area.

Tropics Heating Up

We have 2 active tropical cyclones (Florence, Gordon), and another incipient one in the Atlantic Basin. Tropical Storm Gordon could strengthen into a hurricane before landfall on the Gulf Coast between Mississippi/Alabama overnight into Wednesday. Heavy rain could induce flash flooding in southern portions of these states. The immediate coastline will be at risk of storm surge flooding. Florence doesn’t pose an threat to land. The disturbance shown below that’s furthest east is a tropical wave that’s just emerged off the coast of Africa. This is worth watching as it has a high chance of becoming a tropical cyclone and its eventual track could pose a threat to portions of the Lesser Antilles.

NYC Weather Update – Aug 27, 2018

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The dog days of summer arrive in full force this week before we close out the month of August. With a strong Bermuda high in place well southeast and secondary high pressure in the area, we will see a heat wave take place from today into Thursday. Several days of hot, humid weather are on tap until a cold front moves through Thursday, bringing the potential for strong thunderstorms and much cooler air in its wake.

Rest of today – hot, though not quite as humid as it will be later this week. High temperatures in the low-90s with mostly sunny skies expected.

Tuesday – even hotter, and more humid than today with high temperatures in the mid-90s with sunny skies.

Wednesday – yet another hot, oppressively humid day with high temperatures in the mid-90s. Both Tuesday and Wednesday should see heat index values above 100°F due to high dew point values as well.

Thursday – a cold front is forecast to push through the area Thursday. Along and ahead of this front, we are expecting the chance for some scattered strong to severe thunderstorms given the ample moisture available and hot temperatures. Temperatures will still be hot, in the low-90s, before this frontal boundary passes through. Behind this cold front, temperatures will be 10-15°F cooler Friday into the weekend.

 

NYC Weather Update – Jul 23, 2018

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Wet weather this weekend continues into much of this week as we settle into a pattern favoring rain chances every day. Tropical moisture remains firmly entrenched in the region due to an anomalously strong upper trough and deep layered southerly flow. A strong high pressure center over the western North Atlantic will block the progress of frontal boundaries until next weekend when we finally get a break from the wet weather.

Rest of today – mostly cloudy, high temperatures in the low-80s. Chances for scattered showers throughout the remainder of the day and into the overnight hours.

Tuesday – mostly cloudy, high temperatures again in the low-80s. Lower chances for rain than the rest of the week due to the high pressure mentioned above retrograding west. This should keep things largely dry.

Wednesday – best chance for sustained bouts of heavy rain as a cold front approaches from the west but stalls out and dissipates. High temperatures in the low-80s with mostly cloudy skies again. Flash flooding could be a concern given the atmospheric water content and the southerly steering currents parallel to the frontal boundary, favoring training of storms hitting the same area repeatedly.

Thursday – yet another day with the chance for showers and thunderstorms, high temperatures in the mid-80s and mostly cloudy.

NYC Weather Update – Jun 25, 2018

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This week starts off with a string of pleasant, dry conditions with Canadian high pressure in control. Temperatures will be a bit below normal due to the cool influence of this continental Canadian air mass. We get a chance for some rain mid-week, then temperature start warming up. Looking ahead, we could be seeing an extended period of 90°F+ temperatures starting the end of this week.

Rest of today – mostly sunny, high temperatures around 80°F.

Tuesday – another great day with high temperatures just about 80°F and lots of sun.

Wednesday – increasing clouds as the next storm system approaches the region. High temperatures again about 80°F.

Thursday – overnight into Thursday, rain chances start to pick up as a warm front approaches the area from the southwest. This will lead to chances for showers and thunderstorms, which will continue into Thursday. High temperatures will remain around the 80°F.

NYC Weather – Jun 12, 2018

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A mostly dry, and pleasant week is in store for us. We will see a steady warming trend, with the only real chance for wet weather happening Wednesday accompanying the passage of a warm front and cold front. Great weather lasts right into the weekend.

Rest of today – cool and sunny with high temperatures below normal in the low-70s due to the influence of easterly onshore winds.

Wednesday – a warm front will approach from the southwest. Ahead of that frontal boundary, we could see chances for mainly stratiform showery rain during the late morning hours. Behind this warm front, expect a humid feeling high in the low-80s with mostly cloudy skies until the arrival of the trailing cold front. This second frontal boundary has a better chance to fire off a few thunderstorms, which could be locally strong, late in the evening and into the overnight hours.

Thursday – high pressure returns and gives us a nice sunny day of high temperatures in the low-80s with westerly winds bringing in warmer air from the interior.

Friday – slightly cooler in the upper-70s to around 80ºF but lots of sun again with high pressure staying in control but shifting east.

NYC Weather Update – May 21, 2018

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We start this week off with above average warmth, which will only be punctuated by one day of cooler, wetter weather tomorrow. High pressure returns from Wednesday through the end of the week, bringing us more sunny weather, as well as temperatures gradually increasing to the low-80s by the end of the week. Looking ahead towards Memorial Day weekend, Saturday looks to be the best day, with some rain chances Sunday and Monday.

Rest of today – mostly sunny, with high temperatures in the upper-70s.

Tuesday – a weak disturbance will move through the area along with a warm front. This will yield rain chances later in the day, with the potential for heavy downpours in stronger storms that develop. With cloud cover and rain, temperatures will be significantly cooler, in the upper-60s.

Wednesday – behind this warm frontal passage Tuesday, temperatures should rebound into the upper-70s on Wednesday with mostly sunny skies.

Thursday – a cold front will push through going into Thursday but high pressure will build quickly and this is anticipated to be a dry frontal passage. Temperatures should remain decently mild with highs in the low-70s and mostly sunny skies.

NYC Weekend Weather – Apr 27, 2018

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A wet end to the week will lead to a better first half of the weekend. Showers could occur again on Sunday, but we’ll once again dry out to start next week. A big shift in weather patterns will take place next week with a dramatically warmer air mass to move into the region. Summer-like temperatures in the low-80s by late next week will be a possibility.

Rest of today – cloudy with high temperatures in the upper-50s and rain. Rain beginning this morning, but tapering off in NYC by late afternoon around 4PM, just before the evening rush. Given the set up of winds from the south flowing over a warm front pushing though, some elevated thunderstorms are possible today.

Saturday – nice day on tap with mostly sunny skies and temperatures into upper-60s. Clouds increase late with the chance of scattered showers increasing overnight as a cold front passes through.

Sunday – lingering rain chance early, with conditions improving later and clouds diminishing. Cooler with highs in the upper-50s in the wake of the cold front above.