CIMSS Satellite Blog

Tropical Storm Bertha became the Atlantic Basin’s second tropical storm on 03 July 2008. GOES-12 IR images and QuikSCAT and ASCAT satellite winds (above) from the CIMSS Tropical Cyclones site on following day (04 July 2008) showed some bursts of convection, and verified the presence of tropical storm force winds. The CIMSS wind shear product (below) indicated that Bertha  existed in an environment of low wind shear, which was favorable for continued intensification.

Meanwhile, on the previous day (03 July 2008), the afternoon MODIS visible image and Land Surface Temperature product (below)  showed mostly cloud-free conditions and very hot temperatures across much of the Desert Southwest region of the United States. Death Valley in California reached a high temperature of 122º F, the hottest day so far this summer season (121º F had been reached at that located a few times in June 2008); other high temperatures in the region that day included 118º F at Bullhead City, Arizona and 115º F at Laughlin, Nevada. While the MODIS LST values were generally about 20-30º F higher than the actual air temperatures that were measured in instrument shelters about 5 feet off the ground,  the LST product is still useful for depicting where the hottest areas might be (since the coverage of stations that report air temperature is somewhat sparse).

While the Atlantic Ocean tropical cyclone season has been relatively quiet thus far, the Eastern Pacific Ocean was showing some signs of activity in late June 2008. Products from the CIMSS Tropical Cyclones site such as AMSU brightness temperature (above) and Satellite Consensus (SATCON) tropical cyclone intensity estimates (below) were useful to forecasters at the National Hurricane Center, as noted in their Tropical Storm Boris discussion from 29 June 2008:

TROPICAL STORM BORIS DISCUSSION NUMBER 13
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL

800 PM PDT SUN JUN 29 2008

THE RAGGED EYE VISIBLE EARLIER HAS BEEN OBSCURED BY NEW CONVECTION NEAR THE CENTER…ALTHOUGH EXCELLENT BANDING ALOFT IS APPARENT IN AN AMSU PASS AT 0045 UTC. THE ADVISORY INTENSITY OF 60 KT IS A BLEND OF SUBJECTIVE DVORAK ESTIMATES OF 55 KT FROM TAFB AND SAB…A CIMSS ADT OF 65 KT…AND A CIMSS AMSU ESTIMATE OF 66 KT.

Not far to the west of Boris, Tropical Storm Cristina was also present over the Eastern Pacific Ocean. ASCAT satellite wind vectors were helpful in verifying the intensity of Cristina, as seen in on GOES-11 visible and IR imagery with ASCAT data superimposed (below).

A 30 June 2008 National Hurricane Center discussion for Tropical Storm Cristina also noted

TROPICAL STORM CRISTINA DISCUSSION NUMBER 11
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL

200 AM PDT MON JUN 30 2008

THE CLOUD PATTERN ASSOCIATED WITH CRISTINA HAS BECOME LESS ORGANIZED OVER THE PAST SEVERAL HOURS. THERE IS A RATHER SHARP EDGE TO THE HIGH CLOUD MASS OVER THE EASTERN SIDE OF THE SYSTEM…INDICATIVE OF EASTERLY VERTICAL SHEAR. THIS SHEAR IS AT LEAST PARTIALLY DUE TO THE UPPER-LEVEL OUTFLOW FROM TROPICAL STORM BORIS LOCATED NOT FAR TO CRISTINA’S EAST.

This sharp eastern cloud edge was quite evident on GOES-11 IR imagery (below), which also displays the CIMSS wind shear product.

One factor influencing the lack of organized tropical storm activity in the Atlantic so far this season may have been the persistent Saharan Air Layer and airborne African dust that was frequently observed over the tropical Atlantic basin during the month of June 2008 — note the presence of significantly lower MIMIC Total Precipitable Water (TPW) values during the 27-30 June 2008 period (below) within the 10-20º N latitude band over the Atlantic Ocean, compared to the much higher TPW values over tropical East Pacific where Tropical Storms Boris and Cristina were seen. One impact of such a high amount of African dust may be the cooler than normal Sea Surface Temperatures across the tropical Atlantic, which would be a negative factor for tropical cyclone formation.

Just 11 days after deadly Cyclone Nargis made its devastating landfall in Myanmar (also known as Burma), Meteosat-7 IR imagery from the CIMSS Tropical Cyclones site (above) showed a new tropical disturbance that was moving northwestward across the Irawaddy Delta region of Myanmar on 13 May 2008. The Joint Typhoon Warning Center issued the following Tropical Cyclone Formation Alert at 20:30 UTC:

WTIO21 PGTW 132030
MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE FORMATION ALERT//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN 150 NM EITHER SIDE OF A LINE FROM 16.5N 96.1E TO 19.4N 92.1E WITHIN THE NEXT 12 TO 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY ISSUANCE OF NUMBERED TROPICAL CYCLONE WARNINGS AT THIS TIME. WINDS IN THE AREA ARE ESTIMATED TO BE 25 TO 30 KNOTS. METSAT IMAGERY AT 131800Z INDICATES THAT A CIRCULATION CENTER IS LOCATED NEAR 16.7N 95.7E. THE SYSTEM IS MOVING WEST-NORTHWESTWARD AT 06 KNOTS.
2. REMARKS: RECENT ANIMATED INFRARED SATELLITE IMAGERY AND A 121210Z SSMI MICROWAVE IMAGE INDICATE PRONOUNCED LOW-LEVEL CYCLONIC TURNING OF CONVECTION AT THE WESTERN END OF THE MONSOON TROUGH. HOWEVER, MORE RECENTLY, CONVECTION HAS WANED SOMEWHAT IN RESPONSE TO LAND INTERACTION. THE CIRCULATION CENTER IS CURRENTLY TRANSITING
GENERALLY NORTHWESTWARD ACROSS THE YANGON DELTA REGION OF MYANMAR. OBSERVATIONS FROM YANGON AS OF 131300Z, SUPPORT A 25 TO 30 KNOT CIRCULATION WITH SEA LEVEL PRESSURES NEAR 1000 MB (3 MB PRESSURE FALLS OVER THE PAST 24 HOURS) AND SUSTAINED WINDS AT 10 KNOTS GUSTING TO 20 KNOTS OUT OF THE NORTHEAST. A PARTIAL 130301Z ASCAT
IMAGE ALSO INDICATES STRONG WESTERLIES TO THE SOUTH OF THE CENTER WITH SUSTAINED EASTERLIES TO THE NORTH, FURTHER PROOF OF CYCLONIC TURNING. THE CENTER CURRENTLY LIES UNDER LOW VERTICAL WIND SHEAR JUST SOUTH OF THE SUBTROPICAL RIDGE AXIS WITH FAVORABLE SOUTHWESTERLY DIFFLUENCE ALOFT. THOUGH THE DISTURBANCE IS CURRENTLY OVER LAND, MINIMAL DEGRADATION OF THE LOW LEVEL IS EXPECTED DUE TO THE LOW LYING TOPOGRAPHY AND FAIRLY QUICK TRANSIT
OVER THE LOW-LYING COASTAL REGION OF SOUTHERN MYANMAR. EMERGENCE INTO THE BAY OF BENGAL IS EXPECTED WITHIN THE NEXT 12 TO 18 HOURS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 25 TO 30 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1000 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS GOOD WITH THE ONLY LIMITATION BEING TEMPORARY LAND INTERACTION.

CIMSS satellite-derived atmospheric motion vectors and products (below) indicated that the upper-tropospheric winds, divergence, and deep layer shear were all relatively weak  over the region at that time.