WEATHERAmerica Newsletter, Saturday, December 13, 2025; WEATHER HAZARDS 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)

 

Some Thunderstorms May APPROACH Severe Limits

S FL

Scattered Locations In

BC, WA

(High Winds; Pressure Gradient Derived, Topographically Enhanced

 

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

 

ScatteredIsolated Locations In Locations In

BC, WA Coastline

(QPF 1 - 4")

 

WINTER WEATHER POTENTIAL

(potential for Moderate Icing, Snow 2 - 4" or more, and/or temperatures below 10 deg F)

 

Isolated Locations In

PA....NJ

(Snow; 2 - 4")

Scattered Locations In

N BC....N. C AB....SK....MB....ON....Lower MI....OH....WV,,,,N, C VA....DC....MD....DE....NJ....PA....NY....CT....RI....MA....VT....NH....ME....N NB....QB....NL

(Intense Cold)

GLOBAL WEATHER SUMMARY

(a review of important weather features around the world)

 

IODC

ECMWF; METEOBLUE; EUMETSAT

 

A stormy turn leads to a colder pattern....

A large storm complex crossing the Tigris/Euphrates watershed into Persia will be followed by another shortwave, linking to a moisture pool over Ethiopia and the Red Sea. The numerical models are putting out some impressive amounts of rain and snow, with the latter issue largely enhanced by elevation in the Zagros and Alborz Ranges. Despite the relative warmth on Saturday, this may turn out to be an all-snow event in the Caucasus, Kurdistan, and the Caspian Sea shoreline communities on Tuesday and Wednesday.

Another issue to deal with: the monster Arctic vortex over Siberia, which will link with the southern branch storm progressing out of Turkey and the eastern Mediterranean Sea. Late week could see the freeze line drop all the way into northern Saudi Arabia, Kuwait and the Persian Gulf communities. By December 22, ahead of the next storm in the sequence, some warmth may move through the Middle East and on into the Indus Valley. But with a powerful, stable cAk gyre in northernmost Russia and tendency for a trough complex southward into Iraq, winter has likely only just begun from the Levant into Pakistan and Afghanistan.

 

HIMAWARI 8

METEOBLUE; Kochi University

 

The satellite imagery attached is proof that all of those proclamations about a historic Phase 8 display of the Madden-Julian Oscillation  were just...drivel. The MJO once again is incoherent, with tropical forcing concentrated in two clusters: western Indonesia and the equatorial Indian Ocean and across the Equator from the Marianas Islands throughout Oceania. This structure and position is not favorable for continued widespread coverage of Arctic air across North America. The linkage to the polar westerlies is weak, while the connection with the southern branch is strong enough and will favor a significant storm at some point that crosses Mexico into the south central U.S. The set-up of tropical convection matches the forecast of widespread warmth across the lower 48 states between December 15 and 29. Only after that point would a tendency for cold and more winter precipitation appear. In the meantime, a vicious, long-lived Arctic regime will colver much of Russia through the Central Asian Republics into Iraq and Iran.

Moisture is seen across Australia and New Zealand, as is an Antarctic vortex. This could be a very stormy time in and around the subcontinent, but concern is growing that a heat ridge will ensnare the major population centers along the Pacific shoreline while the Outback and Australian southern points see repeated chances at heavy thunderstorms.

 

GOES WEST

METEOBLUE; NOAA/NESDIS

 

Despite what appears to be a quiet time frame across the USA, the very active eastern Pacific Basin hints otherwise. The sub-Aleutian mAk vortex and Gulf of Alaska gyre are accompanied by a vigorous equatorial moisture axis below Mexico and Central America, enhanced by the MJO out of the central theater of the big ocean. This configuration has a chance at spinning up something special, even though the numerical model impressions are routinely boring. The warmth across the western states will soon migrate to the Great Plains/Texas and points eastward.

 

GOES EAST

NOAA/NESDIS

 

The vast Arctic air mass is anchored by a cAk vortex in northern Hudson Bay. The edge of the cAk domain runs roughly from Oklahoma to the Carolinas, while a small disturbance is developing across East Texas and Louisiana. This impulse will hook up with the thermal boundary, and will pose the chance for a light/moderate snow from middle Appalachia into the Mid-Atlantic region.  Despite the seeming abundance of bitter cold, odds are warmer values will dominate most of the lower 48 states in the near term and medium range.

You can clearly see a temperature transition from the northern Andes Range into Bolivia, Paraguay and Uruguay, with a hot, humid regime across the Amazon River watershed, while a milder, drier air mass is over Chile and Argentina. But also notice the mA vortex impacting the Tierra Del Fuego region, with very cold values and squalls.

 

METEOSAT

ECMWF; METEOBLUE; EUMETSAT

 

The very mild presentation across most of Europe may be altered in the medium range, but not before. Southerly flow across much of the subcontinent is due to an elongated trough complex from the British Isles to Morocco, That process should increase ridging across Scandinavia, which in itself will allow for cold air drainage across much of Russia (while eastern Europe sees more chances for cool weather and precipitation, both frozen and liquid types. Lacking a strong -NAO signature (for now at least), no extreme colder air is likely through most European nations through the next ten days.

Note that the westerlies are now hitting the Equator, with a frontal structure and thunderstorms entering westernmost Africa. Ridging remains strong from Niger through the eastern 2/3 of the Sahara Desert, in a pattern that may soon favor unseasonable cold (possibly in the new year). Convective cells are common across the southern half of the continent, with a rare, well-developed cold front from Zambia into South Africa.