MY 2021 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #46 (Weekend Edition)
*******Note that forecasts and outlooks in this post are NOT the official forecast from the National Hurricane Center (NHC). They are my own detailed views on the Atlantic tropics based on current observations and latest computer model runs. As such do not make decisions based on my posts...consult news media...watches and warnings from your local weather office...and any evacuation orders issued by local governments to make the most informed and best decisions. Visit the NHC website hurricanes.gov (hurricanes dot gov) for the latest watches/warnings and official forecasts on active tropical cyclones.**********
...SATURDAY JULY 10 2021 11:11 PM EDT...
Satellite image as of 0000Z. Areas of interest circled in yellow are not mentioned in the NHC tropical weather outlook. Areas circled in a green dashed line are in the NHC 5-day tropical weather outlook. Areas circled in a solid green line are in the NHC 2-day tropical weather outlook:
NHC TAFB Surface Analysis 1800Z:
GFS Model Upper-Level Winds 1800Z:
See remnants of Elsa section below for an update on the remnant frontal cyclone of the former tropical storm. See area of interest #1 section for information on the northwest Atlantic low pressure recently added into the NHC tropical weather outlook at 8 PM EDT.
REMNANTS OF ELSA...The remnant frontal cyclone of what was Tropical Storm Elsa continues moving rapidly northeast and has recently entered the far North Atlantic after crossing Newfoundland and southern Labrador. The vigorous frontal cyclone remains supported by the divergence zone of the upper trough approaching from eastern North America…resulting in an ongoing area of gusty winds and sea swells southeast of the center where the cyclonic circulation of the storm is aided by it’s fast northeast speed. This area of gusty winds recently passed over Newfoundland. The southeast corner of Newfoundland (St John’s and vicinity) is still seeing gusty winds from the trailing southwest edge of Elsa’s remnant frontal cyclone which should wind down over the next couple of hours. With impact to land coming to an end and Elsa no longer a tropical cyclone…this is my final statement on Elsa on this blog. (Normally I would have made my final blog statement on Elsa yesterday when it lost tropical characteristics…however because I am on vacation I do not have frequent access to update the special messages on the home page of this site to provide updates on Elsa’s remnants impacts to land.)
Here are some of the strongest Environment Canada (weather.gc.ca) station reports of wind (mph) generated by Elsa over southern Labrador and Newfoundland over the last several hours (value in kph kept in parenthesis):
**Mary’s Harbour NL…sustained 9 (15) (17:30 local time)
**St Anthony NL…sustained 21 (35)…gust 28 (45) (13:30 local time)
**Badger NL…sustained 12 (19)..gust 23 (37) (18:30 local time)
**St John’s NL…sustained 21 (34)…gust 50 (81) (16:30 local time)
AREA OF INTEREST #1…Satellite imagery of quickly organizing frontal low pressure in the northwest Atlantic taken at 1801Z…left is true-color…right is colorized infrared…small circulation of low pressure circled in red:
Over the last day or so…a cold front trailing from Elsa formed over the northwest Atlantic while supported by the eastern divergence zone of the upper trough over eastern North America…essentially an elongated area of low surface pressure separating the cool air associated with the upper trough and warm air associated with nearby upper ridging to the east. Other than a thunderstorm complex along the front that occurred offshore of North Carolina for a period of time on Friday…the thunderstorm activity along the front has been insignificant. So when the NHC in their tropical weather outlook highlighted an ordinary linear band of showers and thunderstorms along the front and near 42.5N-61W earlier this evening at 8 PM EDT…it was a bit of a head-scratcher as to why until rewinding the satellite imagery to around 1800Z earlier this afternoon (a sample of that imagery is shown above). Satellite imagery around that time revealed a small low pressure spin offshore of Nova Scotia with some tropical character and somewhat organized thunderstorms that seemed to also be ventilated by the anticyclonic outflow of the nearby upper ridging to the east. This occurred near the north edge of the warm Gulf Stream waters…however as of late the thunderstorm activity has pulsed downward into the now weaker linear band we see on satellite pictures as this small low pressure spin moves northeast into cooler water while steered by the deep-layer southwesterly flow between the Atlantic surface ridge and upper trough. Therefore I assign 0% odds of tropical cyclone formation…especially as the upper air temps are too warm to support instability for thunderstorms over the cooler water. This is my planned final statement on this system on this blog unless it continues to be mentioned in the NHC outlook by my next update.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (0000Z Jul 12)…0% chance of tropical cyclone formation (east-southeast of Newfoundland near 42N-49W)