WEATHERAmerica Newsletter, Saturday, September 20, 2025; WEATHER HAZARDS And GLOBAL SATELLITE IMAGES

[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 TX....OK....C, E KS....MO....IL....KY....IN....W OH....MI....C ON

 

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

 

Isolated Locations In

AZ....E NV....UT....W CO....W, S WY....ID....SW MT

(QPF 1 - 2")

Scattered Locations In

N TX....OK....C, E KS....MO....IL....KY....IN....W OH....MI....C ON

(QPF 1 - 4")

Isolated Locations In

WA....S BC

(QPF 1 - 2")

 

EXCESSIVE HEAT RISK

(Potential For Temperature To Exceed 95 deg F)

 

Isolated Locations In

S CA Deserts....NV....UT....C, S WY....CO....NM....TX....W, C OK....W KS....W NE

Isolated Locations In

C, S FL

GLOBAL WEATHER SUMMARY

(a review of important weather features around the world)

 

IODC

ECMWF; METEOBLUE; EUMETSAT

 

The slow, torturous end to summer heat continues.

Nobody said that the process of losing heat would be sudden across the Middle East, Iran, and Central Asia. What is happening is that the series of large storms moving along in a semizonal flow through Eurasia is  slowly driving polar air masses further and further south. The heat ridge complex straddling Persia into Pakistan is eroded with every pulse progressing west to east in the polar jet stream, producing significant rain and thunderstorms in a belt comprising Turkey, the Caucasus, the Caspian Sea shoreline, and the Central Asian Republics. Saudi Arabia, the Persian Gulf and United Arab Emirates will not see significant temperature drops until the second half of October. But just consider that when the front comes through, the refreshing air mass in Turkmenistan and Ukraine will be coming to visit the Levant eastward through the Indus River watershed.

Just give the process time to work!

 

HIMAWARI 8

METEOBLUE; Kochi University

 

A disturbing aspect of the forecast in the Indian and western/central Pacific Ocean is the sudden increase in tropical cyclone activity. The typhoons Ragasa and Neoguri are quite strong, with well-defined eyes and abundant moisture draw. There are also five other candidate tropical waves in this theater. But be sure to note that none of these systems seem to be a contributor of energy and moisture to the polar westerlies, and therefore are unlikely to alter tghe upper flow in North America. There is a remnant of monsoonal moisture across eastern Asia, and the likelihood of cooler air following the southwest flow by next weekend.

A powerful cold front has pushed into northern Australia. Thus boundary will stall and trigger heavy thunderstorms in the equatorial sections of the subcontinent. The strongest part of the frontal structure is currently targeting New Zealand and Oceania.

 

GOES WEST

NHC; METEOBLUE; NOAA/NESDIS

 

Another tropical cyclone will form south of Mexico shortly, and most model guidance suggests perhaps another two such storms will impact the Mexican Riviera before heading westward below Cabo San Lucas. The early presence of a Central American gyre is somewhat of a puzzlement during a La Nina episode, and could foretell a major precipitation event in Texas and much of the Dixie states. The Deep Gulf Of Alaska Low is close to vortex status, and is linked to energy over the Aleutian Islands. That would likely mean a pumping up of a heat ridge over the eastern half of the continent which will not break down until the first week of October.

 

GOES EAST

NHC; METEOBLUE; NOAA/NESDIS

 

Tropical Storm Gabrielle remains very disorganized due to shearing influences and dry air entrainment. Most projections from NHC suggest that the system will become a Category 2 hurricane as it passes east of Bermuda in the near term. Other "Cape Verde" impulses moving off of equatorial Africa may grow into depressions and named storms within the following ten days. Those disturbances may have a better chance at intensification and emerging as a threat to larger population centers, as increased ridging seems probable across the western Atlantic Basin.

The broad mean trough or weakness across the center of North America will generate opportunities for heavy to severe thunderstorms from Texas and the Great Plains into the Ohio Valley. There is a fair chance this precipitation could linger before moving into Appalachia and the Eastern Seaboard later in the new week. Hot air may overtake the pattern from west to east in the medium range.

South America is a study in contrasts. Hot and humid weather with diurnal thunderstorms occur across the northern half of the continent. But impressive cold fronts continue to progress form the Pacific Ocean into the southern Atlantic Ocean. Argentina into southern Brazil has cool, wet weather while Chile has cases of dry air with record cold.

 

METEOSAT SEVERI

ECMWF; METEOBLUE; EUMETSAT

 

Summer weather is ending across Europe, with the progression of strong troughs and upper lows through the subcontinent. Thunderstorm threats will mostly be from France into Germany and Poland, later involving the Ukraine and Turkey. Each passage of the impulses in the polar westerlies should push the warmer values out, and there may be some cases of below normal temperatures above 45 N Latitude.

The Saharan heat ridge is still alive and well, and covers the northern third of Africa. The ITCZ is active from Yemen through the equatorial regions. Cooler air has overtaken much of the southern portion of the African continent. There are four possible cold frontal passages below the Congo Basin into South Africa.