WEATHERAmerica Newsletter, Saturday, September 6, 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)

 

Some Thunderstorms May APPROACH Severe Limits

S CA....AZ....NM....W, C TX....OK Panhandle....CO....E UT....WY....W, C MT....ID....OR....WA....BC

ISOLATED Severe Thunderstorms

(Microbursts, Large Hail, Isolated Tornadoes/Waterspouts)

FL Peninsula....Coastal, GA, SC, NC, VA. MD, DE....NJ....S NY....CT....RI....MA....VT....NH....Coastal ME....NB....PEI....NS....Newfoundland

 

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

 

Isolated Locations In

FL Peninsula....Coastal, GA, SC, NC, VA. MD, DE....NJ....S NY....CT....RI....MA....VT....NH....Coastal ME....NB....PEI....NS....Newfoundland

(QPF 1 - 2")

Isolated Locations In

S CA....AZ....NM....W, C TX....OK Panhandle....CO....E UT....WY....W, C MT....ID....OR....WA....BC

(QPF 1 - 2")

 

EXCESSIVE HEAT RISK

(Potential For Temperature To Exceed 95 deg F)

 

Scattered Locations In

S, C CA....NV....ID....UT....AZ....NM....W TX....OK Panhandle....Far W KS....NE Panhandle....W SD....S MT....WY....CO

GLOBAL WEATHER SUMMARY

(a review of important weather features around the world)

 

IODC

ECMWF; METEOBLUE; EUMETSAT

 

Turkey holds the key to the ongoing pattern change.

Using the Black Sea as a moisture source, the series of disturbances and frontal structures will likely inundate Thrace and Anatolia with heavy thunderstorms over the next ten days. This rainfall is an important player, and notifier, of ending the widespread torturous heat across the Middle East, Iran and Pakistan, since the cooler values behind the front and moisture will make gradual inroads southward, ultimately cracking the long-standing heat ridge complex.

But the process takes time. The passage of a cold pocket and upper low through southern Russia may enable the boundary to finally reach, or surpass, the Kurdistan and Alborz Ranges within a week or so. The next arc of the cP boundary will most likely be through Mesopotamia and the Zagros Mountains in Week 2, and then northern Saudi Arabia, Kuwait and the Persian Gulf in the third week of this month. As always, the UAE and central Arabian Peninsula will continue to roast until after October 1.

But the core of the message is that "help is on its way...."

 

HIMAWARI 8

METEOBLUE; Kochi University

 

The Asian monsoonal axis has been replaced, more or less, by a Madden-Julian Oscillation wave in Phases 2 and 3. This is important as the direction of energy and moisture will now be in the tropics, and not the polar westerlies. Which in turn should slow down cold air mass penetrations in North America as well as central and eastern Asia. Typhoon potential will be more limited in the western pacific theater, but one or two disturbances could acquire a name that would impact the Philippines, Taiwan, the Korean Peninsula, and Japanese Archipelago.

Note that Australia has resumed its sequence of Antarctic cold frontal passages, The southeastern portion of the subcontinent could see high elevation snowfall and record cold, and progress into New Zealand a few days thereafter.

 

GOES WEST

NOAA/NESDIS

 

The still well-formed Hurricane Kiko poses a threat, most likely as a tropical storm, to the Big Island Of Hawaii within 72 hours. The lack of shear in the environment envelope has allowed Kiko to maintain intensity and formation over marginally cooler waters. The Kiko circulation may reach Oahu before recurving to the northeast as it gets picked up, and sheared apart, by the polar westerlies.

Note that after all this time in the summer season, we still see an Aleutian + Gulf of Alaska Low formation. The storm complex pumps up -EPO and +PNA ridging, which then triggers polar air mass intrusions through the central and eastern half of North America. But when the recombinant low ejects shortwaves out into the Pacific Northwest and the Prairie Provinces, the cold gets evacuated in a hurry. This 500MB configuration gives us a few clues as to how the 2025-26 winter season will turn out. And to be honest, it gives snow and cold lovers most anywhere in the lower 48 states some hope that

the DJF trimester will be at least normal, if not excessive, with negative temperature and positive precipitation anomalies.

 

GOES EAST

NHC; METEOBLUE; NOAA/NESDIS

 

Forecasting tropical cyclone potential this season has been difficult, to be sure. While the ITCZ has been hyperactive with incredible amounts of rainfall in equatorial Africa, most impulses within the discontinuity have fallen apart with no impacts on the western side of the Atlantic Basin. The exceptions to this ongoing trend, Barry and Erin, still were viewed as minimal outside of flooding rain and wave generation. The presence of areas of dry, dusty and hot air ejected out of the Sahara Desert have mostly nullified current and recent past convective circulation. The National Hurricane Center has essentially voided chances of development for impulses between the Cape Verde Islands and the Greater Antilles, this coming after excitement about wind and rain threats to the island chains in the new week. It may be premature, however, to cancel the whole SON period, since the arrival of the westerlies across northern Africa may stop the cTw regime from becoming enmeshed into some of the monster waves moving west from the Horn Of Africa.

The deep polar air mass has two cold fronts associated with its progression through North America. Note the cold upper low over James Bay, a rarity for early September. The remnants of Hurricane Lorena in New Mexico have linked with the second thermal boundary, and could trigger widespread heavy rain and severe weather in Texas and Louisiana on Sunday night into Monday.

One powerful trough and cold front is exiting southern Brazil, while another (much larger) mPk air mass is offshore of Chile and likely to move across the southern third of South America. Most of the northern two-thirds of the continent are hot, humid with a strong cluster of convection over Colombia through Ecuador and Peru.

 

METEOSAT

ECMWF; METEOBLUE; EUMETSAT

 

For the most part, it is time to let go of the notion that heat is still a prominent issue in the forecast for Europe. While there almost certainly will be spikes of hotter air across the Mediterranean countries (courtesy of nearby Saharan Heat ridge), cold frontal progression will serve as a limiting factor in generating cooling demand across much of the European subcontinent. As can be seen on satellite images, cold pools and southward advance of mP air is becoming routine. Thunderstorms may be quite strong from France into Eastern Europe and Asia Minor, with a very cool period setting up over Ukraine and southern Russia.

There may be very cold values in the southern Atlantic Ocean, but Africa on the whole remains quite warm, unlike South America and Australia. There are four giant ITCZ waves from Djibouti to Dakar, and one offshore of the Cape Verde Islands. It remains to be seen if a genuine tropical cyclone threat will emerge anytime soon in the Atlantic Basin.