HURRICANE DOLLY

Radar loop of Hurricane Dolly

Hurricane Dolly has become the second hurricane of the 2008 hurricane season. Dolly is barely a hurricane, and is still struggling to build a complete eyewall. Visible satellite loops show an eye developing, and heavy thunderstorm activity continues to increase near the core of the storm. Dolly has good upper-level outflow to the west and north, but restricted on the south side, where an upper level low pressure system is still interfering. Maximum surface winds measured by the SFMR instrument on the current Hurricane Hunter aircraft inside Dolly were 74 mph (65 kt), measured at 4:17 pm EDT. Brownsville, Texas long-range radar shows the eyewall is complete on Dolly's west side, but is struggling to get established on the east side. Radar estimated rainfall amounts of 1/10 of an inch have fallen on the Texas/Mexico coast so far, thanks to the outermost spiral bands of Dolly.


The intensification potential for Dolly remains high, but until Dolly can form a full eyewall, it won't be able to take full advantage of the favorable environment. Wind shear over Dolly is about five knots, and is expected to remain below ten knots over the next two days. An upper level high pressure system is moving into place over the storm, which should enhance Dolly's upper-level outflow and allow more rapid intensification. Dolly is over waters of 29°C. The waters cool to about 28°C by midnight tonight as Dolly approaches the coast and passes over a cool ocean eddy. The depth of the warm waters Dolly is over has decreased, and the Tropical Cyclone Heat Potential has fallen from about 40 to 20 kJ/cm**2. This decreases the potential of rapid intensification. Our skill in making intensity forecasts is poor, but it currently appears that Dolly only has enough time to intensify into a Category 1 hurricane. A Category 2 hurricane still a possibility, though. The track forecast
The track forecast has changed little since this morning, with the various computer models predicting pretty much the same behavior as they did 12 hours ago. Four models are predicting a landfall in northeastern Mexico--the UKMET, ECMWF, NOGAPS, and GFS--and two models are predicting a Texas landfall--the GFDL (just north of Brownsville) and the HWRF (near Corpus Christi). Dolly could come ashore anywhere within the cone of uncertainty, and one should not assume the storm will track down the "skinny black line" NHC has drawn through their official forecast. The timing of Dolly's landfall, as predicted by the computer models, will be anywhere from 8 am - 10 pm Wednesday. However, the GFS and ECMWF hint that Dolly may stall out right by the coast Wednesday, and some slow and erratic motion is possible tomorrow before the storm finally comes ashore.
SOURCE

From NOAA
500 PM EDT TUE JUL 22 2008

DOLLY IS BEING CLOSELY MONITORED BY THE NWS RADAR FROM
BROWNSVILLE...NOAA BUOYS..SATELLITE AND VERY IMPORTANTLY...BY AN
AIR FORCE HURRICANE HUNTER AIRCRAFT. THE RADAR IS MEASURING 75
KNOTS AT ABOUT 20 THOUSAND FEET AND SHOW NUMEROUS RAINBANDS ALREADY
APPROACHING THE COASTS OF NORTHEAST MEXICO AND SOUTHERN TEXAS.
DVORAK ESTIMATES SUGGEST THAT DOLLY IS A HURRICANE AND WIND DATA
JUST RECEIVED FROM THE RECONNAISSANCE AIRCRAFT HAVE CONFIRMED IT.
INITIAL INTENSITY IS 65 KNOTS. WITH THE PREVAILING LOW
SHEAR...DOLLY IS FORECAST TO REACH THE COAST A LITTLE BIT STRONGER.

DOLLY IS MOVING TOWARD THE NORTHWEST OR 305 DEGREES AT 9 KNOTS.
THIS GENERAL TRACK SHOULD CONTINUE FOR THE NEXT 24 HOURS WITH A
SMALL DECREASE IN FORWARD SPEED. ON THIS TRACK...THE CORE OF DOLLY
SHOULD BE NEAR THE US/MEXICO BORDER WITHIN THE WARNING AREA ON
WEDNESDAY. DOLLY IS LARGE CYCLONE AND TROPICAL STORM FORCE WINDS
WILL BEGIN TO AFFECT THE AREA TONIGHT. AFTER LANDFALL...DOLLY
SHOULD TURN MORE TO WEST AS A SUBTROPICAL RIDGE BUILDS TO THE NORTH
OF THE CYCLONE. MOST OF THE TRACK MODELS ARE IN GOOD AGREEMENT
BRINGING THE CORE OF DOLLY INLAND IN ABOUT 24 HOURS. IT SHOULD BE
RE-EMPHASIZED THAT...DUE TO THE INHERENT UNCERTAINTIES...ONE MUST
NOT FOCUS ON THE EXACT LANDFALL POINT IN THIS FORECAST.

DUE TO THE SLOW MOTION AT LANDFALL...DOLLY COULD DUMP VERY HEAVY
RAINS IN THE AREA.

Tropical storm Dolly update

500 PM EDT MON JUL 21 2008

THE STRUCTURE OF DOLLY APPEARS TO BE UNDERGOING VERY GRADUAL
CHANGES. THE OUTERMOST CONVECTIVE BANDS HAVE BEEN WEAKENING
TODAY...WHILE CONVECTION HAS BEEN SLOWLY ON THE INCREASE NEAR THE
CIRCULATION CENTER. THE RADIUS OF MAXIMUM WINDS IS NOW MUCH
SMALLER...AS DETERMINED FROM STEPPED-FREQUENCY MICROWAVE RADIOMETER
DATA THAT RECENTLY INDICATED A MAXIMUM SURFACE WIND OF 45 KT ABOUT
45 N MI NORTHEAST OF THE CENTER. DOLLY IS HEADED TOWARD A RELATIVE
MAXIMUM IN OCEAN HEAT CONTENT...AND IT IS BENEATH A LARGE
UPPER-LEVEL ANTICYCLONE THAT COVERS NEARLY THE ENTIRE GULF OF
MEXICO. IT SEEMS TO BE TAKING A WHILE...HOWEVER...FOR AN INNER
CORE TO BEGIN TO TAKE SHAPE...SO IT IS RATHER UNCERTAIN HOW MUCH
DOLLY WILL TAKE ADVANTAGE OF ITS ENVIRONMENT. ALL OF THE INTENSITY
MODELS FORECAST AN UPWARD INTENSITY TREND UNTIL FINAL
LANDFALL...BUT THEY DO NOT AGREE ON THE AMOUNT OF STRENGTHENING.
THE SHIPS AND LGEM MODELS FORECAST ABOUT 65 KT IN 48 HOURS...WHILE
THE GFDL IS A LITTLE HIGHER AT 75-80 KT. SINCE THE ENVIRONMENT
APPEARS SO CONDUCIVE FOR STRENGTHENING...THE OFFICIAL FORECAST
AGAIN LEANS TOWARD THE HIGHER GFDL SOLUTION. ANOTHER COMPLICATION
IN THE INTENSITY FORECAST IS NOT KNOWING EXACTLY HOW FAST DOLLY
WILL REACH THE COAST. IF IT MAKES LANDFALL SOONER THAN THE
OFFICIAL TRACK INDICATES...IT MIGHT RUN OUT OF TIME TO REACH THE
OFFICIAL FORECAST PEAK INTENSITY. BUT IF THE OPPOSITE
OCCURS...DOLLY WOULD HAVE A LITTLE MORE TIME OVER THE WARM WATERS.

DOLLY CONTINUES TO MOVE QUICKLY...AND THE INITIAL MOTION ESTIMATE
REMAINS 300/16. WHILE IT IS A LITTLE UNNERVING TO OBSERVE THIS FAST
MOTION AND FORECAST THE CENTER OF DOLLY TO TAKE A COUPLE OF DAYS TO
REACH THE COAST...ALL OF THE DYNAMICAL MODELS INSIST THAT THE
FORWARD SPEED WILL BE ABOUT HALF ITS CURRENT VALUE BY TOMORROW
NIGHT. THE MODELS AGREE SURPRISINGLY WELL ON THE SLOW-DOWN...SO
THE OFFICIAL TRACK FORECAST...IN TERMS OF FORWARD SPEED...IS RIGHT
IN LINE WITH THE MODEL CONSENSUS. THE MODELS DO NOT GO INLAND IN
EXACTLY THE SAME LOCATIONS...HOWEVER. THE GFS AND UKMET FORECAST
DOLLY TO CROSS THE COAST OF NORTHEASTERN MEXICO...WHILE THE GFDL
AND HWRF TRACKS GO INTO SOUTHERN TEXAS. THE OFFICIAL TRACK
FORECAST IS A LITTLE NORTH OF THE CONSENSUS...GIVING RESPECT TO THE
AGREEMENT BETWEEN THE NWS HURRICANE MODELS...THE GFDL AND HWRF.
THIS NEW TRACK IS NOT MEANINGFULLY DIFFERENT THAN THE PREVIOUS
ONE...EXCEPT TO BE A LITTLE FASTER. IT IS AGAIN IMPORTANT TO
EMPHASIZE THAT...WITH RELIABLE MODELS ON BOTH SIDES OF THE OFFICIAL
TRACK...ONE SHOULD NOT FOCUS ON THE EXACT LANDFALL LOCATION IMPLIED
BY THE OFFICIAL TRACK.

WARNINGS WILL LIKELY BE REQUIRED FOR PORTIONS OF THE HURRICANE AND
TROPICAL STORM WATCH AREAS LATER TONIGHT.

Hello Dolly!!

DOLLY HEADING TOWARD THE YUCATAN PENINSULA...

A TROPICAL STORM WARNING IS IN EFFECT FOR THE YUCATAN PENINSULA OF
MEXICO FROM THE BORDER WITH BELIZE TO CAMPECHE MEXICO. A TROPICAL
STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE EXPECTED
WITHIN THE WARNING AREA WITHIN THE NEXT 24 HOURS.

A TROPICAL STORM WATCH IS IN EFFECT FOR THE COAST OF BELIZE FROM
BELIZE CITY NORTHWARD TO THE BORDER WITH MEXICO. A TROPICAL STORM
WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE POSSIBLE WITHIN THE
WATCH AREA...IN THIS CASE WITHIN THE NEXT 12 TO 24 HOURS.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA...INCLUDING POSSIBLE
INLAND WATCHES AND WARNINGS...PLEASE MONITOR PRODUCTS ISSUED
BY YOUR LOCAL WEATHER OFFICE.

AT 500 PM EDT...2100Z...THE CENTER OF TROPICAL STORM DOLLY WAS
LOCATED NEAR LATITUDE 18.9 NORTH...LONGITUDE 85.0 WEST OR ABOUT 220
MILES...350 KM...EAST OF CHETUMAL MEXICO AND ABOUT 165 MILES...265
KM...SOUTHEAST OF COZUMEL MEXICO.

DOLLY IS MOVING TOWARD THE NORTHWEST NEAR 14 MPH...22 KM/HR. A
NORTHWESTWARD OR WEST-NORTHWESTWARD MOTION IS FORECAST DURING THE
NEXT COUPLE OF DAYS...WITH A GRADUAL DECREASE IN FORWARD SPEED
EXPECTED BY TUESDAY. ON THIS TRACK...THE CENTER OF DOLLY WILL MOVE
ACROSS THE YUCATAN PENINSULA OF MEXICO TONIGHT...EMERGE OVER THE
SOUTHERN GULF OF MEXICO ON MONDAY...AND MOVE INTO THE SOUTHWESTERN
GULF ON TUESDAY.

DATA FROM AN AIR FORCE RECONNAISSANCE AIRCRAFT INDICATE THAT MAXIMUM
SUSTAINED WINDS REMAIN NEAR 45 MPH...75 KM/HR...WITH HIGHER
GUSTS. SLIGHT STRENGTHENING IS POSSIBLE TONIGHT BEFORE DOLLY
REACHES THE YUCATAN PENINSULA. GRADUAL STRENGTHENING IS FORECAST
ON MONDAY AND TUESDAY AFTER DOLLY EMERGES OVER THE SOUTHERN GULF OF
MEXICO.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 175 MILES...280 KM
FROM THE CENTER. DOLLY COULD PRODUCE WINDS NEAR TROPICAL STORM
FORCE...ESPECIALLY IN GUSTS...OVER THE WESTERN TIP OF CUBA TONIGHT.

THE MINIMUM CENTRAL PRESSURE RECENTLY REPORTED BY THE RECONNAISSANCE
AIRCRAFT WAS 1008 MB...29.77 INCHES.

DOLLY IS EXPECTED TO PRODUCE RAINFALL OF 4 TO 6 INCHES ACROSS THE
NORTHERN YUCATAN PENINSULA OF MEXICO AND WESTERN CUBA...WITH
ISOLATED MAXIMUM AMOUNTS UP TO 10 INCHES. AN ADDITIONAL 2 TO 4
INCHES IS EXPECTED IN THE CAYMAN ISLANDS...WITH A STORM TOTAL OF UP
TO 8 INCHES.

REPEATING THE 500 PM EDT POSITION...18.9 N...85.0 W. MOVEMENT
TOWARD...NORTHWEST NEAR 14 MPH. MAXIMUM SUSTAINED WINDS...45 MPH.
MINIMUM CENTRAL PRESSURE...1008 MB.

AN INTERMEDIATE ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE
CENTER AT 800 PM EDT FOLLOWED BY THE NEXT COMPLETE ADVISORY AT 1100
PM EDT.