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).
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
Servicio Meteorológico Nacional of 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.
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.
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.
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.
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.