Loc: Beautiful Honolulu Hawaii
Cosme Waning, for Now
Thu Jul 19 2007 09:06 AM
Cosme has crossed over 140W and the NHC in Miami has handed over responsibility to the Central Pacific Hurricane Center (CPHC) in Honolulu.
Meanwhile, Cosme has been downgraded to Depression status, as cooler SST's and persistent shear have apparently taken their toll on this system.
After several small, short lived convective bursts in the SE and SW quads the past 12 hours or so, it appears that Cosme is waning as I write this, about 1am HST.
However, I wouldn't shut the book quite yet, as the next few days might be interesting.
From the latest (11pm HST) advisory package from the CPHC:
"COSME IS STILL SHOWING SIGNS OF LIFE ...
OVER THE PAST 6 HOURS AN AREA OF COLD CLOUDS ON THE SOUTHEAST SIDE OF COSME HAS EXPANDED AND COVERED THE CENTER. THAT MADE IT MORE DIFFICULT TO PINPOINT THE CENTER ON CONVENTIONAL INFRARED IMAGERY...BUT MICROWAVE IMAGERY SHOWED THE CENTER NICELY ... THERE WAS ALSO A NICE QUIKSCAT PASS (WHICH) SHOWED 30 KT WINDS EXTENDING AS MUCH AS 90 NM NORTHWEST OF THE CENTER."
But since this advisory, convection has again waned, but it may yet again flare and pulse during the overnight hours (Hawaii time) during the diurnal convective max cycle.
And if we do get a good burst near and over the LLC that persists, in spite of the shear, then central pressure may again drop and an upgrade might be in the works.
"WHILE THE TRACK HAS BEEN VERY CONSISTENT...FORECASTING THE INTENSITY REMAINS MORE UNCERTAIN. COSME CONTINUES TO MOVE OVER FAIRLY COOL WATER...ABOUT 77 DEGREES FAHRENHEIT...BUT THE SYSTEM HAS SHOWN SIGNS OF INTENSIFICATION ... WE KEPT THE INITIAL INTENSITY UNCHANGED AT 30 KT...
BUT IF THE CONVECTION NEAR THE CENTER PERSISTS OVER THE NEXT SIX HOURS IT IS *LIKELY* WE WOULD TAKE COSME BACK UP TO TROPICAL STORM INTENSITY ON THE NEXT BULLETIN."
But it's really touch-and-go and much depends on the ability of the convection to sustain itself and the system as a whole.
"COSME SHOULD REMAIN OVER RELATIVELY COOL WATER WITH FAIRLY LOW SHEAR OVER THE NEXT 48 HOURS...SO IF THE SYSTEM DOES LOSE ALL IT/S CONVECTION DURING THAT PERIOD...IT MAY WELL BECOME TOO WEAK TO HAVE MUCH CHANCE TO RE-INTENSIFY."
And on the flip side of the coin:
"IF COSME MANAGES TO KEEP SOME CONVECTION (AS IT MOVES WEST) ...IT WILL START MOVING BACK OVER WARMER WATER. IF SHEAR REMAINS WEAK ENOUGH AT THAT POINT...COSME MIGHT WELL RE-INTENSIFY."
It's hard to predict exactly what will happen to Cosme in the next day or two, hence:
"THESE UNCERTAINTIES KEEP OUR CONFIDENCE IN THE INTENSITY FORECAST RATHER LOW."
Looks like it could go either way. I wouldn't be too suprised to see it fizzle altogether, as it's happened so often in the past. But I've also seen a few depressions (and even remnants) flare up and regenerate as they approach warmer waters near the Islands.
(IMAGE OF COSMES' PROJECTED PATH TOWARDS AND JUST SOUTH OF THE HAWAIIAN ISLANDS)
And finally, a word from the good folks at the NWS forecast office in Honolulu, in their latest synoptic discussion (seperate from the official CPHC advisory discussion above) ...
"THE REEMERGENCE OF DEEP CONVECTION WITHIN TROPICAL DEPRESSION COSME NEEDS TO BE OF CONCERN TO THOSE WHO ARE MONITORING ITS PROGRESS. IF THESE THUNDERSTORMS PERSIST...COSME MAY HAVE A CHANCE TO REINTENSIFY LATER TONIGHT OR THURSDAY.
REGARDLESS OF ITS CURRENT OR FORECAST INTENSITY...ALL RESIDENTS IN THE STATE OF HAWAII NEED TO CLOSELY FOLLOW FUTURE ADVISORIES ON COSME.
EVEN IF THIS TROPICAL SYSTEM PASSES BY THE ISLANDS AS A WEAK LOW...THE PRESSURE GRADIENT BETWEEN THIS LOW AND HIGH PRESSURE TO THE NORTH WILL BE CAPABLE OF INCREASING WINDS TO SPEEDS NEAR OR ABOVE THE WIND ADVISORY THRESHOLD OVER LAND. THESE WINDS COULD BE ESPECIALLY STRONG OVER SOME OF THE HIGHER TERRAIN ON THE BIG ISLAND...AND POSSIBLY ON MAUI. (Orographically enhanced winds, something Floridians never have to think about!)
FLOOD WATCHES MAY ALSO BE REQUIRED FOR PARTS OF THE STATE AS THE MOISTURE PLUME FROM COSME MOVES UP FROM THE TROPICS."
Hmmm..... Just a quick check of the IR loop before submitting this post reveals a new flare-up of strong thunderstorms in a tight, band-like formation on the WEST side of the LLC. Have a look and follow along with the convective trends, as they will make or break the future of Cosme.
Sorry to be making such lengthy posts, but there does seem to be increasing interest in Cosme as she approaches the Islands. Hope they've been interesting and informative.
PS: Thanks for your replies. It's great to get others' perspectives on the situation, as well. Keep 'em coming!