Rammasun Nears South China – Atlantic Remains ‘Quiet’ As Record Cold / Heat Affect US

(By Steve Gregory - Substituting for Dr. Masters who is on Vacation.)

Deadly Typhoon Rammasun is located about 440NM NW of Manila heading towards the South China Island of Hainan (population of 9 million). Latest satellite imagery estimates indicate the central pressure is near 955mb, with Max sustained winds of 80Kts. Over the last 6 hours, both IR and water vapor imagery has shown a significant improvement in the convective banding structure and a clearing out of the eye – both indicative of re-intensification.



Figure 1: Latest Enhanced IR image of Rammasun clearly shows a well defined eye within a more symmetrical imagery signature. Banding is evident with extremely cold cloud tops to the North/Northeast of the center.

Until last night, official and model forecasts pointed towards a re-intensification of Rammasun to a solid CAT 3 or Cat 4 prior to reaching Hainan. However, despite the significant improvement in the satellite signature, most forecast models have trimmed the intensity forecast to a strong CAT 2 or minimal CAT 3 within 12 hours, with a slow weakening thereafter. Model projections call for a strong CAT 1 or low end CAT 2 by the time the storm makes landfall along the north coast of the Island near Haikou around 10Z on Friday due to its interaction with land and somewhat cooler SST’s near the South China coast.

The China Meteorological Administration has issued a "orange warning for typhoon" for the provinces of Hainan, Guangdong, and Guangxi, all in southern China. The three provinces have a combined population of over 150 million people. An orange warning is the second-highest level in China's four-tier warning system. Once the cyclone passes by Hainan, the storm is expected to make its final landfall in extreme northern Vietnam with Tropical Storm strength winds. (Note: Vietnam's National Center for Hydro-Meteorological Forecasting has also issued a typhoon warning for portions of northern Vietnam.)



Figure 2: The latest available JTWCTrack forecast for Rassmasun shows the cyclone passing across the northern coast of Hainan as a CAT 2 Typhoon between 06Z and 18Z Friday.

Meanwhile, up on deck is TD#10 which has formed near 10N / 135E with estimated max winds of 30Kts. Imagery indicates the system is essentially stationary, with a slight westward drift noted over the last 12 hours. As late as yesterday, most of the reliable forecast models had forecast this system to become a strong Typhoon over the next 3-5 days with a slow forward acceleration towards the WNW and then NW towards Taiwan. However, the last 4 global model forecast cycles have dramatically changed, with most models now depicting a weak Tropical storm development. Nonetheless, latest official forecasts still call for the development of a CAT 1 typhoon over the weekend, with a track that continues to take aim on Taiwan. This forecast appears to be the most likely scenario based on the most recent SAT imagery.



Figure 3: The above NEXSAT image from last night shows both Rammasun and what is now, TD #10



Figure 4: Track/Intensity forecast for TD #10 shows the cyclone intensifying to CAT 1 as it approaches Taiwan on Tuesday. However, please note that the latest GFS model run does NOT forecast this system to intensify; contrary to yesterday’s model runs calling for a significant typhoon.

TROPICAL ATLANTIC

The Tropical Atlantic remains quiet – but there are continuing signs that conditions are trending towards a more ‘seasonal’ environment, as the first relatively significant Tropical wave emerges off the west African coast – and one that isn’t embedded in the Saharan Air Layer (SAL)! Deep convection is associated with the tropical wave – though the latest animated SAT imagery indicates relatively weak Vorticity associated with this system.

In general, Water Vapor imagery shows a general moistening across the CARIB eastward to the African coast – though wind shear, while falling off during the past few days, remains relatively high across much of the CARIB. In addition, with SST’s still slightly below normal, an overall stable environment persists across much of the CARIB eastward to the African coast. Bottom line: no cyclone formation is expected during the next 7 days



Figure 5: The most significant tropical wave is shown emerging off the West African coast earlier this morning, with waves clearly seen over the central Tropical Atlantic and a more complex wave structure approaching the eastern CARIB. These latter waves MAY may manage to bring some well needed showers to portions of the CARIB over the weekend and next week.




Figure 6: Strong and deep convection associated with the Tropical Wave near the African coast, with minor, but significant convection observed with the central AT and near CARIB waves.




Figure 7: The SAL is well north of the tropical wave off the African coast – the first time this has happened this summer; reflecting the typical intra-seasonal trend that typically begins by late JUL.




Figure 8: This derived image depicts total precipitable water – with somewhat greater totals now shown extending across the deep tropics from just east of the CARIB to the African coast, while some ‘moistening’ of the atmosphere noted over the CARIB as well.



Figure 9: The 850mb Vorticity analysis over the eastern ATL shows a minimal VORT structure associated with the wave that has just emerged off the African coast – while also indicating a far more significant VORT signature associated with the next tropical wave expected to reach the coast late FRI.

RECORDS FALL ACROSS THE NATION

The major upper level TROF that dug southward over the eastern US during the past few days has brought unseasonably ‘cold’ air to much of the central and eastern US during the last couple of days, while the persistent western ridge has led to numerous record highs, especially to the PAC NW northward into portions of western Canada. At the same time, severe drought conditions continue across much of the west, with numerous wild fires in the PAC NW.

Some notable Record Lows reported over the past 2 days include:

Springfield, IL: 52ᵒ
Ottumwa , IA: 49ᵒ
International Falls, MN: 39ᵒ
Little Rock, AR: 62ᵒ
St. Joseph, MO: 51ᵒ
Norfolk, NE: 47ᵒ
Lincoln, NE: 48ᵒ
Moline, IL: 52ᵒ
Mobile, AL: 64ᵒ
Pensacola, FL 66ᵒ

Some Record Low ‘MAX’ Temps on Tuesday:

Goodland, KS: 62ᵒ
Appleton, WI 66ᵒ
Rhinelander, WI 62ᵒ

Some Record Highs:

Moses Lake, OR: 106ᵒ
Pendleton, OR: 105ᵒ
Seattle, WA: 89ᵒ
Yakima, WA: 101ᵒ
Redmond, WA: 100ᵒ
Hanford, WA: 105ᵒ
Pasco, WA: 109ᵒ

Record High ‘MIN’ Temp:

Elko, NV: 71ᵒ - (Also the second warmest Low ever recorded!

And to round it all out – an amazing RAINFALL Record of 0.85” was set yesterday at Tonopah, Nevada.

Steve Gregory