WEATHERAmerica Newsletter, Saturday, July 12, 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)

W, N TX....S, E OK....N, C OK....C, S MO....S IL....KY....TN....W NC....W VA....WV....E OH....PA....NY....W NJ....DE....MD....DC

Some Thunderstorms May APPROACH Severe Limits

FL....Coastal GA, SC, NC 

Some Thunderstorms May APPROACH Severe Limits

N, C QC

Some thunderstorms May APPROACH Severe Limits

E BC....W AB

Some Thunderstorms May APPROACH Severe Limits

C CO....C NM

 

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

 

Scattered Locations In

W, N TX....S, E OK....N, C OK....C, S MO....S IL....KY....TN....W NC....W VA....WV....E OH....PA....NY....W NJ....DE....MD....DC

(QPF 1 - 4")

Isolated Locations In

FL....Coastal GA, SC, NC

(QPF 1 - 3")

Scattered Locations In

Far N ON....N, C QC

(QPF 1 - 3")

Isolated Locations In

C CO....C NM

(QPF 1 - 3")

 

EXCESSIVE HEAT RISK

(Potential For Temperature To Exceed 95 deg F)

 

Scattered Locations In

S AB....S BC....WA....OR....CA....AZ...NV....ID....MT....WY....CO....NM....TX....OK....KS....NE....SD....S ND....SW MN....W IA....MO....AR....LA....MS....Al....TN....KY....WV....S, C OH....PA

C, E NY....NJ....DE....MD....DC....VA....NC....SC....GA....FL

GLOBAL WEATHER SUMMARY

(a review of important weather features around the world)

 

IODC

ECMWF; METEOBLUE; EUMETSAT

 

Mesoscale upper air disturbances are a tease. Scattered showers and thunderstorms may pop up, but not last long.

A small dent in the vast heat ridge complex covering an area from northern Africa to Pakistan has allowed a surface trough, with cumulus and cumulonimbus attached, to enable a small drop in readings across parts of Iran. Thunderstorms need an energy and temperature differential zone to be meaningful, which in this case is simply not present. The impulse will ride out into Afghanistan and western Pakistan on Sunday, allowing for a complete rebuild of the subtropical high. A "worse than before" scenario is promised by all of the numerical models, to the point where the core of the heat ridge may be over or near Tehran on July 22, with a circulation spread from Turkey on the west to below Ulaanbaatar Mongolia on the east.

In plain language, more chances for extreme temperatures are in order for the entirety of the Middle East, Persia, and steppes/deserts of Central Asia through the rest of the month. And more harsh dryness and temperatures are likely into the first week of September in this part of the world.

 

HIMAWARI 8

METEOBLUE; Kochi University

 

The Madden-Julian Oscillation is in two wave clusters. One convective group is between Sri Lanka and Sumatra, and may be the start of a Phase 2 MJO percolation. The other, much larger impulse, bordering on the synoptic scale, covers Phases 5 into 7. There is some potential for a tropical cyclone formation, but so far connection to the polar westerlies is marginal, not interacting with the broad storm sequence over the Aleutian Islands and Gulf of Alaska. That lack of linkage favors a larger heat ridge over the U.S. such as proposed by the ECMWF panels. The Asian monsoon is strong over India but fragmented in China, the Korean Peninsula and Japan.

 

GOES WEST

NOAA/NESDIS

 

There is diminished tropical cyclone potential with the ITCZ impulses progressing westward beneath Central America. But further development cannot be ruled out. The monsoonal moisture fetch through Mexico is also weaker, but should start to increase and build toward the American Southwest on Sunday and Monday. Of larger concern is the Gulf of Alaska Low and its sibling structures across the Aleutian Islands, which will move eastward over top of the Sonoran heat ridge through southern Canada and the northern tier states adjacent to the International Border. Most of the forecast guidance takes the subtropical high eastward toward the Great Plains and merges with the Bermuda High. If so, the monsoon could increase rapidly through the Desert and Intermountain Regions.

 

GOES EAST

NOAA/NESDIS

 

There are plenty of upper weakness and frontal structures across central and eastern North America that are preventing a major heat blast from occurring. The near term sees Mexican monsoonal moisture from becoming entrenches in the Southwest (which should be happening now) and instead turning through Texas and into the Great Plains. Hence flooding and thunderstorm threats are still mentioned in Texas and the Midwest. It is only a matter of time before the Sonoran and Bermudan subtropical highs undergo expansion, and then the tropical impulses from the ITCZ will follow deep mean easterlies into the major islands, Florida and the Gulf of Mexico. You can also see a developing cold low in Nunavut AR which could have impacts in Canada and places in the northern tier states of the USA.

South American imagery has that still-active ITCZ, with convective circulation embedded from Colombia into Africa. There is still potential for a tropical cyclone below Central America and Mexico. Much of Brazil is drier, but temperatures and dewpoints will rise as a powerful storm sequence off the coast of Chile progresses into Paraguay, Uruguay, and Argentina. That system could bring a return to heavy rain and immense amounts of mountain snowfall.

 

METEOSAT

ECMWF; METEOBLUE; EUMETSAT

 

It is probably inevitable that Europe gets into a short to medium heat wave in the 6-10 day period, what with the strong Saharan heat ridge nudging into the Mediterranean Sea and a broad cutoff low at 500MB over the northern Atlantic Ocean. But a closed disturbance and cold pool in Germany and Poland is suppressing warmth in central sections of the subcontinent, and will later go on and keep much of Russia in near to below normal temperatures. But the southern European nations and Asia Minor are in for more hot weather through at least the remainder of July.

Now we must watch the ITCZ waves in Africa, as conditions upstream (lighter winds, more upper ridging, water warmers) are looking favorable for tropical cyclone development. The large impulse west of the Cape Verde Islands is riddled with dry air and dust. But note that convective circulation in Niger and Nigeria (and the two others approaching from the Nile Headwaters and the Horn Of Africa). Riding underneath a broad subtropical high, chances for a named storm are increasing near the Lesser Antilles in about ten days. The Saharan and Kalahari ridge complex keep the northern and southern African nations hot and dry (with the exception of a cold frontal passage in the vicinity of Gqeberha and Durban).