WEATHERAmerica Newsletter, Saturday, October 18, 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)

 

ISOLATED Severe Thunderstorms

(Microbursts, Large Hail, Isolated Tornadoes)

N FL....W GA....E AL....C, E TN....C, E KY....W VA....WV....W PA....OH....Lower MI....C, E ON....Far W QC

 

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

 

Scattered Locations In

N FL....W GA....E AL....C, E TN....C, E KY....W VA....WV....W PA....OH....Lower MI....C, E ON....Far W QC

(QPF 1 - 3")

Isolated Locations In

BC....WA....OR....N CA....N NV....ID....W MT....NW WY

(QPF 1 - 3")

 

WINTER WEATHER POTENTIAL

(potential for Moderate Icing, Snow 2 - 4" or more, and/or temperatures below 10 deg F)

 

Scattered Locations In

BC....WA....OR....N CA....N NV....ID....W MT....NW WY

(Snow; Above 4000 Feet; 4 - 24")

Isolated Locations In

N AB....N SK

(Snow; 4 - 8")

Isolated Locatkions In

W ON

(Snow; In Squalls; 4 - 8")

GLOBAL WEATHER SUMMARY

(a review of important weather features around the world)

 

IODC

ECMWF; METEOBLUE; EUMETSAT

 

The stubborn heat ridge is about to collapse.

 Agreed, it took a while. But most of the numerical model data takes the Persia/Arabian heat ridge down completely after October 25. The cooler air that has been noted across Anatolia, the Caucasus and Trans-Caspian will creep slowly southward, perhaps reaching Kuwait and the Persian Gulf coastline before the end of the month. The temperatures are still in the "pleasant" range, with no Arctic air likely to arrive anytime soon below 35 N Latitude. Thunderstorm potential should become more apparent in the 6-10 day range through the Middle East, Iran, and Pakistan.

 

HIMAWARI 8

JTWC; METEOBLUE; Kochi University

 

The small, somewhat disorganized storm exiting Luzon may briefly become a typhoon, but ultimately head west and break up over central Vietnam and Laos in early week. Contrary to online rumors, the Madden-Julian Oscillation is not associated with this disturbance, as the MJO is reforming over the Indian Ocean after a long period of being incoherent. The attachment to the westerlies and tropical forcing is so far west as to not be an aid in amplifying the polar westerlies, which suggests that there is little potential for a deep polar or Arctic air mass formation and advance into the lower 48 states before October 28. But afterwards the organization of the tropical convection may be altered.

There are still cold frontal penetrations moving through Australia and New Zealand, despite the lateness in the year and looming presence of increased heat from the equatorial regions. That said, much of the eastern half of the subcontinent looks very warm. Thunderstorm threats will grow along the Australian populated Pacific coastline by late in the new week.

 

GOES WEST

METEOBLUE; NOAA/NESDIS

 

There is a disturbance below Mexico which still conceivably crosses the Isthmus of Tehuantepec into the Bay of Campeche. This impulse seems to have been forgotten by prediction sources, but a circulation is plainly visible. Otherwise, the Pacific shoreline of the Mexican Riviera will see the brunt of more heavy rain and thunderstorms, a common occurrence over the past four months.

In another recurring pattern, the Gulf of Alaska vortex is again being followed by another gyre from the Aleutian Islands. Cold air inclusion will be somewhat limited, but enough mPk values advance to present some below normal temperatures through most of central and southern Canada. The key to the progression of large storms from the northern Pacific Ocean is to build snowpack across the American West and the Prairie Provinces.

 

GOES EAST

NOAA/NESDIS

 

The large gale center well south of Newfoundland may become a subtropical storm, with impacts on the fisheries in the Grand Banks and Flemish Cap. The greater concern is the tropical wave complex over and to the right of the Windward Islands. This feature could intensify, sagging below a westerly shear signature in the Caribbean Sea. There is a fair chance for organization into a low-latitude hurricane, and impacts in the Greater Antilles or the Eastern Seaboard cannot (yet) be ruled out. Thunderstorms from the Great Lakes into northeast Texas ahead of a weak cold front may still present problems with energy and transportation into Appalachia on October 19.

Note the powerful cold front moving from Argentina into southern Brazil. I can see another such mPk boundary well west of Chile, which may curtail chances for warming in the southern half of the continent. There are convective impulses across the areas close to the coastline of the Caribbean Sea, but the vast middle along and below the Amazon Valley remain hot and dry.

 

METEOSAT

ECMWF; METEOBLUE; EUMETSAT

 

Europe continues to settle into a semizonal flow signature from the northern Atlantic Ocean. Embedded storms in the polar westerlies may create opportunities for heavy rain and wind across the British Isles and later into Germany and Scandinavia. But pleasantly warm temperatures continue along the Mediterranean Sea, perhaps disturbed by thunderstorms in a rare tropical moisture fetch out of the Canary Islands.

Africa is mostly warm-to-hot, except in the southern third of the continent where a cold front has made strides moving east. Cold fronts have reached the Malagasy Republic, a relatively rare event. The ITCZ is still active and capable of triggering thunderstorms from Djibouti to the Cape Verde Islands. But soon the "CV" hurricane season will be shutting down as shearing westerlies drop in latitude into the equatorial Atlantic Ocean.