WEATHERAmerica Newsletter, Saturday, August 23, 2025; WEATHER HAZARDS And GLOBAL WEATHER SUMMARY

[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)

AL....GA....W SC....W NC....E TN....W VA....WV....W, C PA....W, C NY....C, QC....Labrador

Some Thunderstorms May APPROACH Severe Limits

S FL

SCATTERED Severe Thunderstorms 

(Microbursts, Large Hail, Isolated Tornadoes)

CO....W, C NE....W, C KS....NW OK

Some Thunderstorms May APPROACH Severe Limits

NM....AZ....S CA Deserts....NV....UT....S WY

 

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

 

Isolated Locations In

S FL

(QPF 1 - 4")

Scattered Locations In

CO....W, C NE....W, C KS....NW OK

(QPF 1 - 3")

Isolated Locations In

NM....AZ....S CA Deserts....NV....UT....S WY

(QPF 1 - 2")

Isolated Locations In

C, E ON....N QC

(QPF 1 - 2")

Isolated Locations In

AL....GA....W SC....W NC....E TN....W VA....WV....W, C PA....W, C NY....C, QC....Labrador

(QPF 1 - 2")

 

EXCESSIVE HEAT RISK

(Potential For Temperature To Exceed 95 deg F)

 

Scattered Locations In

S BC....WA....OR....CA....AZ....NV....ID....W MT....W, C WY....UT....CO....SW KS....C, S OK....NM....TX....SW AR....LA....C, S MS....C, S AL....FL....S GA

GLOBAL WEATHER SUMMARY

(a review of important weather features around the world)

 

IODC

ECMWF; METEOBLUE; EUMETSAT

 

There is hope.

That simple phrase is meant to tell residents of the Levant and Iran that the brutal, unrelenting heat will likely ease in about two or three weeks. I have noticed that the 500MB forecasts across Eurasia feature very large tyroughs at 500MB, with embedded cold lows. Progression of these features will eventually crease and break the ridge complex now situated over southwestern Asia. But the process takes time. You will notice increased thunderstorm chances in Anatolia and the Caucasus, moisture from the lower Red Sea coming farther north, and cold frontal penetrations through northern portions of Iraq and Persia in Week 2, and thereafter slightly more moist atmospheric profiles from the Tigris/Euphrates watersheds eastward to the Indus Valley. But until the "easing time" (after September 8), it is still a case of many overheated locations praying for rain and north winds. 

The process takes time.

 

HIMAWARI 8

METEOBLUE; Kochi University

 

The scattershot structure of the Madden-Julian Oscillation is ripe for tropical cyclone development, as evidenced by Typhoon Kajiki approaching central Vietnam. But a likely more important system is forming east of the Philippines. This larger circulation looks to target the central and northern portion of the archipelago, and then head into either Taiwan or southeastern mainland China. The Asian monsoon appears to be weakening, although important precipitation will likely continue over Indochina into the east Asian coastline during the next couple of weeks.

Strong cold fronts are still progressing through Australia, Oceania, and New Zealand. Another frontal structure will sweep across the subcontinent in the new week, with showers and thunderstorms and a sharp drop in temperature from the Outback into the eastern Australian urban areas.

 

GOES WEST

NHC; METEOBLUE; NOAA/NESDIS

 

I am not so much concerned about the disorganized tropical wave below southern Mexico, since its chances of developing into a threat to the Mexican coastal resorts seems minimal with its westward trajectory. But the monsoonal moisture pool over our southern neighbor is important, as much of the higher dewpoint field will be drawn northward through the Desert and Intermountain region, bringing potential for intense diurnal/orographic thunderstorms. This action will weaken the vast heat ridge across the West, forcing the anticyclone to higher latitudes in a +PNA ridge configuration. This is, in effect, the reasoning behind the cool advection east of the Rocky Mountains over the next four days. The Gulf of Alaska Low and Aleutian Low combinant feature will probably eject several more disturbance into the Pacific Northwest around and after Labor Day, breaking down the pattern now taking shape across North America.

 

GOES EAST

NHC; METEOBLUE; NOAA/NESDIS

 

Tropical Storm Fernand is southeast of Bermuda, and headed for open water and likely dissolution in about 5 days from now. The tropical wave approaching the Lesser Antilles should reach depression or named storm status, but may encounter southwest shearing flow over the Caribbean Sea.

Keep your eye on the weak frontal structure across the Gulf Coast and offshore of the Southeast, which may spin up a convective circulation as it produces thunderstorms along the Interstate 10 and 95 corridors. The strongest cold front of the summer so far is now moving into the Heartland and Midwest, and will create opportunities for severe weather as it pushes south and east during the next 48 hours.

Talking about strong cold fronts, take a look at that cP boundary stretching from Bolivia into Uruguay and southernmost Brazil. Another strong cold vortex and front in the southern Pacific Ocean will approach Chile in early week.

 

METEOSAT SEVIRI

ECMWF; METEOBLUE; EUMETSAT

 

Autumn is trying hard to move into Europe. The impressive polar westerlies, with embedded large storms (one of which is the former Hurricane Erin), will have an increased presence across Eurasia over the next three weeks. In time, the associated troughs will wipe out the high heat over the Mediterranean countries, and start the process of wearing down the Saharan/Persian heat ridge complex. Thunderstorms will herald the arrival of the polar air masses across the European subcontinent, with ever-deeper closed 500MB lows progressing from the British Isles into Russia. The hottest readings will continue to be from the Iberian Peninsula into Asia Minor.

The ITCZ is still alive and kicking across central Africa. The Saharan air layer is weakening the large impulse over the Cape Verde Islands, but the other disturbances in the equatorial moisture pipeline are still dumping extremely heavy rain and intense thunderstorms all the way fromYemen into Sierra Leone. Northern and southern Africa remain mostly quite dry and warmer than normal.