WEATHERAmerica Newsletter, Saturday, October 4, 2025; WEATHER EXTREMES And GLOBAL SATELLITE IMAGERY

[Larry Cosgrove]

WEATHER HAZARDS (During The Next 24 Hours)

 

SEVERE WEATHER OUTLOOK
(potential for tornadoes, damaging winds, and large hail within the next 24 hours)

 

Some Thunderstorms May APPROACH Severe Limits

FL Peninsula

 

HEAVY RAINFALL OUTLOOK
(potential for an inch or more total rainfall within the next 24 hours)

 

Isolated Locations In

FL Peninsula

(QPF 1 - 3")

Isolated Locations In

WY....S MT....S SD....NE Panhandle....N CO

(QPF 1 - 2")

Scattered Locations In

NE ND....S MB....W ON

(QPF 1 - 3"; Changeover To Sleet, Snow Possible Late)

 

EXCESSIVE HEAT RISK

(Potential For Temperature To Exceed 95 deg F)

 

Isolated Locations In

SE AZ....C, S NM....SE CO....SW KS....TX....S LA

Isolated Locations In

C, S FL

GLOBAL WEATHER SUMMARY

(a review of important weather features around the world)

 

IODC

ECMWF; METEOBLUE; EUMETSAT

 

Colder air hovers over Russia and Europe.

If you are ready for an honest-to-goodness polar air mass in the Middle East, Persia, or the Indus Valley, patience is required. Granted it is still quite warm on these forecast panels in southwestern Asia, but all we are lacking for a cool atmosphere change is having the storm track drop below 35 N Latitude.It will probably take a trough now in western Europe to make a push south and east toward the Red Sea and Persian Gulf. The tropical cyclone Shakti will have almost no influence on the 500MB flow and configuration, as it will head toward Pakistan and India breaking up in the process. Notice also how dry the air is across the Levant and Iran, another reminder of the presence of the lingering subtropical high.

 

HIMAWARI 8

METEOBLUE; Kochi University

 

Active tropical pattern, to be sure, over the western Pacific Basin. But few influences on the global circulation pattern.

October normally shows an increase in the 500MB configuration flow. That jump in velocity and curvature is often associated with linkage to the Madden-Julian Oscillation convective plumes, or input from typhoons that follow a route from Phases 6,7, and 8 into a developing sub-Aleutian Low or vortex. This year so far has two monstrous vortices covering an area between the Kamchatka Peninsula and the Alaska Panhandle. But the larger storms are moving west into northern Vietnam, Japan or (eventually) the Philippines. The classic Typhoon Injection Syndrome case was of course 2014, which caused the great Buffalo NY snow debacle and later a very cold fall and winter east of the Rocky Mountains.

The MJO signal is now close to Phases 7 and 8, which, if linked to the polar westerlies, may start a transition to a more amplified upper flow in North America. Notice that the broad cold front coming into Australia and Tasmania is hooked into convection across Indonesia. This vigorous thermal boundary will end the warm temperatures over the subcontinent, and could enhance thunderstorm production over the northern territories as well as in New Zealand.

 

GOES WEST

NOAA/NESDIS

 

There are some years when a La Nina episode gets underway that the eastern Pacific Basin has a more active tropical season than its Atlantic Ocean counterpart. That is the case so far during the 2025 hurricane season, with 9 named storms in the Atlantic realm vs. 18 designations to the left of Central America and Mexico.  If this trend keeps up, a useful winter analog may emerge, likely with a vigorous southern branch jet stream. The same goes for the tendency for recurrent huge cold pools and 500MB gyres below the Aleutian Islands and in the Gulf of Alaska. The systems now organizing and moving eastward from those positions are more typical for -ENSO alignments, and a usually a cold-favoring scenario for the NDJFM semester. Something to look out for as the winter season draws near in the USA and Canada.

 

GOES EAST

NOAA/NESDIS

 

The convection and circulation in the Gulf of Mexico is unlikely to develop, but the large tropical wave exiting the Cape Verde Islands should grow into a hurricane as it tracks toward Puerto Rico later in the new week. Judging by the vast ITCZ, which is bubbling with impulses, the potential for more depressions and named storms for the rest of the month in the Atlantic Basin seems high.

An oncoming trough and frontal structure into the Prairie Provinces and the Pacific Northwest is aiding in warm advection over much of the rest of the lower 48 states for the new week. Thunderstorms may precede this feature across the northern third of the U.S. There may be important convection around Coastal Texas and Louisiana from the aforementioned Gulf Coast/Florida systems as well.

Disturbances along the Amazon Basin continue to progress into Central America, and may organize further into depressions or named storms in the eastern equatorial Pacific Basin. The southern part of the continent still has strong cold frontal progression, but temperature responses will be more moderate as we move through the austral spring.

 

METEOSAT

ECMWF; METEOBLUE; EUMETSAT

 

You may have noticed the tendency for full-latitude, neutral-tilt trough formation across Europe. Indeed, the large storm over the North Aea has energy and moisture associated with the tropical cyclones Humberto and Imelda, which in turn brings gusty winds and locally heavy rains from the British Isles into Spain and southern France. A separate disturbance also brings precipitation to Ukraine and western Russia. Cooler temperatures will expand through the subcontinent in the next ten days.

Northern Africa has largely been bypassed by the polar air mass to its north, and temperatures continue to very warm levels with dryness. The thick ITCZ thunderstorms complexes pose new chances for tropical cyclone formation upon release into the equatorial Atlantic Ocean. Cooler air  covers the southern third of the African continent, especially over South Africa and Mozambique.