Cooler risks, Harvey concerns over the next week

A wonderful Tuesday morning to you, and thank you for joining us for our daily morning roundup. If you haven’t checked your email box for the latest details, we will (as always) lay them out in an understandable post-based format here. Today we’re jumping straight into discussion regarding the cooler risks in the weather pattern over the Central United States as well heightened tropical risks across the Western Gulf of Mexico late week and into the weekend.

The cooler risks across the Central United States have been well discussed for several days now, but are finally beginning to come to fruition as troughing begins to develop in Canada and sinks towards the Northern Great Plains. A low pressure system will help to advect cooler air behind its path into the aforementioned regions during the middle of the week, leading to the first “shot” of colder air into the United States.

Northern Plains owns the cooler air first

The most notable area of cooler air will come across the Northern Plains states during the middle part of the week, starting Wednesday morning. A trough currently positioned over the International Border near North Dakota will sink southeastward. At the surface, this will tug colder than normal air into the Dakotas, Minnesota, Wisconsin and Iowa. The anomalous air looks particularly impressive on Wednesday morning.

coldwow

The NAM guidance suite and grid is forecasting low temperatures well into the 40’s across a swath of Minnesota, Iowa, and Wisconsin. With ideal radiational cooling conditions occurring and much colder than normal air residing at about 5000 feet, the potential for these numbers to be realized appears legitimate. The outside potential exists for some frost in the very Northern, higher elevation portions of Minnesota on Wednesday morning as well.

This cooler air will gradually and slowly manifest itself across the Great Lakes region  as whole during the week ahead, particularly during the overnight periods. Low temperatures in the 40’s appear to be quite common, even across much of the AG Belt by Thursday morning, as the colder air aloft spreads eastward and radiational cooling conditions at the surface remain ideal.

The larger-scale, mid level hemispheric height pattern will support the continuation of this overall theme. A +PNA will aid in the development of a ridge over the West Coast, which is expected to strengthen and remain modulated by La Nina-esq tropical forcing. Meanwhile, high latitude blocking in Canada will continue to send cooler air southward to be realized at the surface as disturbances and troughs dig into the Central United States.

Tropical threat may evolve late week as Harvey restrengthens

 

 

GEFS model showing precipitation forecasts in the 99th percentile late this week and weekend.

GEFS model showing precipitation forecasts in the 99th percentile late this week and weekend.

You may have noticed a Tropical Weather Bulletin in your inbox (clients). Over the past 24-48 hours, the open wave remnants of Tropical Storm Harvey have gradually tracked into the Western Caribbean. Most notably, however, they have remained intact when viewed from a birds eye, non-mesoscale pattern view. This is important, as the overall steering currents and low level/mesoscale pattern will eventually restructure to support the strengthening of the system once again as it emerges into the Western Gulf of Mexico later this week.

While forecast models remain somewhat skeptical of development, confidence is increasing given the synoptic-scale support. A large anticyclone, presence of very warm sea surface temperatures in the Western Gulf of Mexico, relatively low shear and favorable steering/organizational currents in the atmosphere will support the strengthening of Harvey late-week. Tropical moisture will likely surge northwestward into the Western Gulf towards the coastal areas of Mexico and Texas as well.

Exactly where the storm tracks remains the main question. A further north track with some interaction with a trough over Texas could send the center of the reformed storm into Texas, while a further south/slower track could send the storm towards the Mexican coast line. Either way, tropical-related impacts appear increasingly likely for the Western Gulf of Mexico states late week and this weekend.

hazardmap_harvey

Interests along the Western Gulf Shores should pay very close attention to the forecast over the next 24 to 48 hours. The restrengthening of the system could prove hazardous for a large area with threats for torrential flooding rains, strong winds, and coastal impacts from surge and wave heights. Stay tuned for further updates in the next 24 hours from our team.

For now, enjoy your Tuesday and we look forward to touching base with you this evening for our PM update and daily recap!