WEATHERAmerica Newsletter, Sunday, December 15, 2024; GLOBAL WEATHER SATELLITE IMAGERY

[Larry Cosgrove]

GLOBAL WEATHER SUMMARY

(a review of important weather features around the world)

 

IODC

ECMWF; METEOBLUE; EUMETSAT

 

Although cold spells are occasionally getting below 35 N Latitude, the main emphasis on Arctic intrusions will continue to be over Russia and the Central Asian Republics. If the longer term forecast models are to be trusted, the concentration of Arctic gto produce important snowfall values will drift to Siberia, Mongolia, and Manchuria as well as the northern half of North America. A shortwave in the upper flow should have enough moisture to produce important snowfall over Turkey into the Caucasus and parts of Iran in the 6-10 day period. Since the energy and amplification of the jet stream configuration is confined (mostly) to vortex and trough formation from the Gulf of Bothnia into Kazakhstan, chances for significant precipitation and major temperature drops will vary from the vicinity of the Black and Caspian Seas southward to the Nile Valley into the vicinity of the Persian Gulf.

 

HIMAWARI 8

METEOBLUE; Kochi University

 

I show a depiction of the Maritime Continent and Southeast Asia to get a glimpse of the Madden-Julian Oscillation, which is totally incoherent and waiting on an intensification and relocation in Phases 6,7, and 8. Most connective emphasis now is with the subtropical jet stream that is pulsing into Mexico. Note the lack of a strong linkage to the polar westerlies and Arctic vortex nearing the Aleutian Islands. In order to produce widespread cold advection into the eastern two-thirds of North America, the MJO must congeal into one larger impulse and link with the northern branch near the International Dateline. Then the "boosted" mAk vortex must sit between Alaska and Hawaii, pumping up a -EPO ridge complex favorable for cold drainage out of the Arctic Circle.

Australia is generally warm/hot with abundant thunderstorms, with the usual alignment of wet North to dry South somewhat inverted. Further east in Oceania and New Zealand, cold frontal passages are bringing occasional squalls and suppressing temperatures.

 

GOES WEST

NOAA/NESDIS

 

The three-pronged storm sequence in the polar jet stream jumps out at you. These disturbances will remain quite deep, and I think keep temperatures across the southern half of Canada down as snowfall rates remain high under periodic flow from Alaska and the North Pole. This current set-up is not favorable for extensive extreme cold, but rather pocketed intrusions of cA diversion that follow a mean storm track from Colorado to New England. Conversely, arguments for long-lasting "blow torch" warming seem very unlikely. The snow line could descend as low as 40 N Latitude, and sleet/freezing rain potential in the Midwest and the (mainly interior) Northeast will be higher than for similar time frames in previous years.

 

GOES EAST

NOAA/NESDIS

 

A significant storm and cold front is slowing down from Ontario southward to Texas, Whereas Canada is mostly snow-covered and warmer temperature forecasts have continually come up short, the southern reaches of the USA have experienced periods of moderation (and in the case of Texas, bouts of record high readings), The boundary may get hung up on Sunday and Monday with the addition of a triple point (cT/mT/cPk) in the south central states. This may lead to some potential for severe weather and heavy rainfall reaching into the Ohio Valley and the Mid-Atlantic.

It is a hotter prediction in Chile and Argentina, with a frontal structure and attendant thunderstorm venet slowly moving into the southern Atlantic Ocean. Northern and central portions of South America are seeing typical diurnal convection with (of course) sweltering afternoon highs with extreme maximum dewpoints.

 

METEOSAT

ECMWF; METEOBLUE; EUMETSAT

 

Westerlies continue across the European subcontinent, keeping the Arctic air over Scandinavia and Russia. One noteworthy aspect of this pattern has been the flexing of the Saharan ridge complex, which has eliminated the subtropical jet stream (which earlier in the season was responsible for torrential rains and cold intrusions into the Mediterranean countries) and reversed colder temperature trends. There will be significant storms in northeastern Europe, and vortex genesis will be a constant issue for the northern Russian Oblasts.

The presence of an upper level low over Chad and the Central African Republic will depress night temperatures in most of the Sahel and central Sahara Desert. All of the equatorial moisture is being diverted southward, with diurnal thunderstorms from the Congo Basin into Mozambique. Note the dryness in South Africa and Angola, as well as Cyclone Chido approaching Nacala,Mozambique (and likely to produce needed rainfall on a track that will lead to dissipation over Zambia).