WEATHERAmerica Newsletter, Saturday, June 15, 2024; WEATHER EXTREMES and GLOBAL SATELLITE DISCUSSION

[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

SE TX....LA....MS....AL....FL....GA....SC....W NC....TN....S KY....VA Panhandle....S WV

ISOLATED Severe Thunderstorms

(Microbursts, Large Hail, Isolated Tornadoes)

N MN....N WI....N MI....C ON

ISOLATED Severe Thunderstorms

(Microbursts, Large Hail, Tornadoes)

S BC....S AB....S, C SK....MB....NW ON

 

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

 

Isolated Locations In

SE TX....LA....MS....AL....FL....GA....SC....W NC....TN....S KY....VA Panhandle....S WV

(QPF 1 - 2")

 

EXCESSIVE HEAT RISK

(Potential For Temperature To Exceed 95 deg F)

 

Scattered Locations In

C, S CA....C, S NV....AZ...UT....WY....CO....NM....S SD....C, S MN....WI....Lower MI....ON Peninsula....W PA....OH....WV....KY....VA Panhandle

W NC....W, C SC....GA....FL Panhandle....AL....TN....MS....LA....AR....TX....OK....KS....NE

GLOBAL WEATHER SUMMARY

(a review of important weather features around the world)

 

IODC

ECMWF; METEOBLUE; EUMETSAT

 

A spike in the heat ridge over Iraq and Iran next week?

By now most living in the Saharan and Persian theaters realize that the giant heat ridge deployment is part of a seasonal action. We are entering the peak time frame for dominance of the subtropical high, which now covers an area from Algeria on the west to northern India in its eastern extent. Occasionally, there will be bubbles in the ridging which creates a brutal spike in heat. This particular event takes shape over Saudi Arabia, then expands and migrates northward on June 22 - 23 to a core covering the Tigris/Euphrates system and most of Persia. Even the normal seabreeze/orographic/diurnal thunderstorms along the Caspian shoreline and Alborz/Zagros Ranges will stop. The monsoonal moisture bank may give parts of South Asia some needed rainfall in nine or ten days. But most of the observed flow or drift aims the convective output to Indochina, the PRC and the Philippines through Japan.

We still have a long way to go to make it through summer.

 

HIMAWARI 8

METEOBLUE; Kochi University

 

I focus on the strong, but oddly concentrated Asian monsoonal moisture fetch from India and the Bay of Bengal into Indochina and the western Pacific shoreline. Not only does this monsoon, which is stronger due to the increased presence of a La Nina episode, provide for excessive rains along the southern and eastern rim of the continent, but also inputs energy and moisture to the polar westerlies. This jet stream "boost will magnify the chance for extensive heat ridging below the USA/Canada border in coming weeks. This is the source of the strong Gulf Of Alaska Low.

Cooler values are reaching into Australia and New Zealand. A weak cold frontal passage into the Outback may generate some showers, but most of the subcontinent will be dry.

 

GOES WEST

NOAA/NESDIS

 

The two easily identifiable features here are the huge Gulf of Alaska Low, which will draw closer to the Pacific Northwest and eject several strong shortwaves that move through the Prairie Provinces over the course of the next two weeks. Besides rather chilly weather in British Columbia and Washington, the passage of relatively strong cold fronts will mean higher potential for hail and tornado bearing thunderstorms along and above the Canadian border.

You can also make out the subtropical jet stream off of Mexico (and the shortwave to the left of the Baja California Peninsula). As long as this feature is present, chances for significant warm-core cyclogenesis affecting the Gulf Coast and Eastern Seaboard will be limited.

 

GOES EAST

NOAA/NESDIS

 

Because the upper flow over the Gulf of Mexico and western Atlantic Ocean is southwesterly, the argument for tropical cyclone formation is marginal at best. Every impulse that pops up gets sheared apart, even those following the flow path at 500MB. Ridging to the left of the moisture stream will expand and build eastward, which might point any independent mesoscale system westward into Mexico. The major issue here again is the heatwave that seems likely to envelop the eastern half of the USA and Maritime Provinces later in the new week.

The ITCZ is merging with the subtropical trough that covers an area from El Salvador through Venezuela and Guyana. Hence the huge area of intense thunderstorms that will target Panama soon. A cold frontal passage through southern Brazil should lower temperatures and lessen chances for rainfall that have plagued teh region during the austral fall.

 

METEOSAT

ECMWF; METEOBLUE; EUMETSAT

 

The broad, cold upper low across the British Isles is the last in its sequence. Retrogression to the south and west will allow for percolation of the huge Saharan heat ridge to bridge into Europe, with a pronounced warming trend. Many locations in the southern portion of the subcontinent will see hot and humid weather. Thunderstorms may occur with upper air disturbances between June 18 - 25, as mesoscale impulses and cold pools show up on model guidance.

The ITCZ is vividly shown on METEOSAT SEVIRI imagery across central Africa, tucked neatly between the Saharan subtropical high and its counterpart, the Kalahari heat ridge. Even the Sahel is getting into the mTw higher dewpoints. When upper winds turn easterly in 6 to 8 weeks, the disturbances may have a chance to move intact across the equatorial Atlantic Ocean and grow into tropical cyclones upon approach to the islands rimming the Caribbean Sea.