WEATHERAmerica Newsletter, WEATHER HAZARDS And GLOBAL SATELLITE IMAGERY; Saturday, July 26, 2025

[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

(Large Hail, Microbursts, Isolated Tornadoes)

N KY....S IL....C, S IN....OH....PA....NY....NJ....DE....MD....DC.....VA....WV

SCATTERED Severe Thunderstorms

(Large Hail, Microbursts, Isolated Tornadoes)

C, S AB....C, S SK....C, S MB....ON/MN Boundary Waters

Some Thunderstorms May APPROACH Severe Limits

C, E QC....Labrador

Some Thunderstorms May APPROACH Severe Limits

N CA....NV....AZ...UT....ID....MT....WY....CO....NM

 

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

 

Scattered Locations In

N KY....S IL....C, S IN....OH....PA....NY....NJ....DE....MD....DC.....VA....WV

(QPF 1 - 4")

Isolated Locations In

C, S AB....C, S SK....C, S MB....ON/MN Boundary Waters

(QPF 1 - 3")

Isolated Locations In

C, E QC....Labrador

(QPF 1 - 2")

Isolated Locations In

N CA....NV....AZ...UT....ID....MT....WY....CO....NM

(QPF 1 - 2")

 

EXCESSIVE HEAT RISK

(Potential For Temperature To Exceed 95 deg F)

 

Scattered Locations In

AZ....C, E NV....C, S ID....UT....WY....C, S MT....S ND....SD....NE....KS....OK....TX....LA....AR....MO....IA....MN....WI....IL....IN....OH....MI....ON Peninsula....C, S NY....NJ....PA....DE

MD....DC....VA....WV....KY....TN....MS....AL....FL....GA....SC....NC

GLOBAL WEATHER SUMMARY

(a review of important weather features around the world)

 

IODC

ECMWF; METEOBLUE; EUMETSAT

 

Unrelenting heat and drought. That sums up the weather for southwestern Asia nicely, doesn't it?

We are technically past the peak of summer (July 23), but it will take a long while to get rid of the heat ridge complex which has been set up over Iran and Saudi Arabia. Climatology for an event like this, which has been normal for the past seven years, would dictate that the pattern or something similar will hold until the second week of September. Around that time, the shortwaves moving across Europe into lower Siberia should deviate to lower latitudes, resulting in a cold frontal approach and thunderstorms around and below 35 N Latitude. If you review the model forecasts for the subtropical high, the core of the very dirty subtropical high looks to remain over central and northern Iran. Only when the center of high pressure relocates to the Arabian Peninsula will the Levant and Persia see cooler air, and the Central Asian Republics have the cool, dry nights that are typical for autumn in the Taklamakan and Gobi Deserts.

 

HIMAWARI 8

METEOBLUE; Kochi University

 

The tropical disturbances over the western Pacific Basin look a lot more serious on satellite imagery than is actually the case in apparent weather. The only candidate to actually become a typhoon is Tropical Storm Kronos, and that circulation should stay well east of Japan as a Category 1 storm. No impacts on the westerlies are projected by the various forecast equations, so downstream effects in North America should be minimal. The splintered Madden-Julian Oscillation has a presence in Phases 2, 6, and 1, which weakens the South Asian monsoon signal while promoting heavy rains across Indochina and Indonesia.

A strong cold front has moved across Australia, with colder air and some instability-related precipitation. New Zealand and Oceania will experience colder temperatures as well. Note the new trough and frontal structure approaching the subcontinent from the southern Indian Ocean.

 

GOES WEST

NOAA/NESDIS

 

There are two features on the GOES WEST image which portend some very turbulent times across the lower 48 states. One is the Phase 1 Madden-Julian Oscillation wave along the Equator from below Hawaii to the Galapagos Islands, which is accompanied by a Rossby wave southwest of Mexico. This disturbed area will enhance heat ridge development in the south central states while also supplying energy and moisture to any tropical waves coming into the Caribbean Sea and Gulf of Mexico. Also see the Gulf of Alaska Low, which is itself linked to a large Aleutian Low and trough. This cyclonic circulation may nullify the Hudson Bay gyre that brings cold air through much of the eastern 2/3 of Canada. There will be no ridge formation in the Northwest Territories and Nunavut AR due to the progression of the westerlies associated with the Alaskan disturbances, which in theory should keep the very cool cPk values above 35 N Latitude, if not further north.

 

GOES EAST

METEOBLUE; NOAA/NESDIS

 

This is the time of the year when we see an increase in tropical cyclone development. The disturbance in the Lesser Antilles is encountering dry/dusty air and some westerly shear aloft, but has a decent chance of growth as it progresses through the Caribbean Sea and possibly into the Gulf of Mexico. Model guidance shows a weakness in Louisiana at 500MB in the 6-10 day range, which is likely where the system, if it survives, will move to.

There is a trans-ridge gap between the Sonoran and Bermudan subtropical highs, which is why the obscenely high relative humidity covers the eastern half of the lower 48 states. Monsoonal moisture has, once again, largely been deviated away from the Desert and Intermountain Regions, and instead to the right of the Rocky Mountains. The vast conjoined heat ridge will start to break apart during the middle of the new week. Thunderstorms along the northern rim of the anticyclone could provide torrential rain and severe weather along and above the Interstate 70 corridor.

Note how dramatically the weather across Chile and Argentina has changed. The Antarctic vortex in the southeastern Pacific Basin has already ejected two strong cold fronts, one of which is bringing heavy rain and polar air into far southern Brazil. The Itcz has lifted northward, exposing the northern half of South America to hot and humid air.

 

METEOSAT

ECMWF; METEOBLUE; EUMETSAT

 

The heat of summer is, for now at least, suppressed across the European subcontinent. The broad North Atlantic trough will move slowly eastward, lowering temperatures while triggering showers and thunderstorms in and about the Danube River watershed. Note that Spain and Portugal will largely remain much warmer than normal, due to nearness of the Saharan heat ridge covering northern Africa. Some of the numerical model guidance builds a heat ridge over France around August 4-5, which may return the unpleasant warmth to the British Isles and interior of Europe.

The ITCZ remains active, with four standing tropical waves from the Cape Verde Islands to Eritrea. The heavy rainfall seen this summer may lurch northward a bit into the Sahel. But most of the nations in the equatorial zone will continue to have excessive moisture and cases of flooding rainfall. The space below the Congo River into South Africa is for the most part warm and dry, but some of the colder oceanic values are reaching as far up as Zimbabwe.