Cover story of today: #Henri has been "hooked" up by an upper-level cutoff low over the eastern US and started to accelerate north, "starburst" outflow pattern heralds a last chance for intensification. Earlier this morning, the Central Cold Cover (CCC) having trapped #Henri for so long finally came to dissipation. As upper-level SW winds from the cutoff flushed toward #Henri and (briefly) mitigated shear problem, the storm took on new appearance and started to form a real core.

https://twitter.com/Minghao_Zhou/status/1428641110558232577

The persistent & very cold cloud tops in #Henri is actually a dubious sign and bad news. In fact, #Henri may have been plagued with such pattern and have halted intensification. 1/n The Dvorak TC analysis technique may refer to such phenomenon as the development of a "Central Cold Cover", or CCC. It's characterized by persistent and enormously large cirrus canopy coverage with no well-defined curved bands or eye appearance.

#Henri (learned today that it's not supposed to be pronounced as "Henry) currently still has its outflow blocked by upper-level NE winds. It can be seen from the loop that the low-level cloud curvatures are out to the NW while upper-level circulation center is tilted to the SE… In sketch terms:

Historical hurricane analog for #Grace.. let's see if it'll drop further south in the Bay of Campeche 👀 Update: #Grace has entered the Bay of Campeche.

Archived content: sketch of how extreme rainfall in Zhengzhou, China was related to (1) moisture transport enhanced by the monsoon gyre, (2) deepening upper-level trough, and (3) leeward inverted trough and upslope flow. 1/n #Henan province has seen 837 stations with 24 hour rainfall amount of 100mm+ (~4"+), 195 stations above 250mm+ (~10"+), with the bullseye centered over the state capital of #Zhengzhou, which was submerged under widespread 400~600mm totals.

ECMWF ensembles showing the Fujiwhara effect between Typhoon #Cempaka 🌼 and Typhoon #Infa 🎆 as the two storms were forecasted to move around each other 🌀 That is one big monsoon gyre circulation over the northwest Pacific, formed by converging easterly trade winds and westerly monsoons. It gave birth to #Cempaka and #Infa. It might give birth to more typhoons.

Typhoon #Cempaka rapidly intensifying while drifting slowly offshore of Guangdong Province, China (#Cempaka name meaning: a type of tree with fragrant flowers 🌼 name origin: Malaysia) #Cempaka has reached 65 kts, 977 hPa per JTWC and 38 m/s, 965 hPa per CMA, despite initial expectations to remain a tropical storm. The land-sea surface friction contrast has caused #Cempaka's most intense convection to locate in the SW quadrant with a slightly elliptic eye.