000
WTNT41 KNHC 300851
TCDAT1
HURRICANE ALEX DISCUSSION NUMBER  19
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL012010
400 AM CDT WED JUN 30 2010
 
ALEX HAS BECOME MUCH BETTER ORGANIZED THIS MORNING BASED ON
WELL-DEFINED BANDING FEATURES WRAPPING INTO THE CENTER AND THE
APPEARANCE OF A SMALL EYE IN INFRARED IMAGERY. AN AIR FORCE RESERVE
UNIT RECONNAISSANCE AIRCRAFT AT 0842Z MEASURED A CENTRAL PRESSURE
961 MB AND 850 MB FLIGHT-LEVEL WINDS OF 82 KT IN THE NORTHEAST
QUADRANT. THE SFMR ABOARD THE PLANE MEASURED A RELIABLE SURFACE
WIND OF 62 KT AND A RAIN-CONTAMINATED PEAK WIND OF 71 KT. THE
DVORAK INTENSITY ESTIMATE FROM BOTH TAFB AND SAB WAS T4.5/77 KT.
THEREFORE...THE INITIAL INTENSITY IS CONSERVATIVELY INCREASED TO 70
KT FOR THIS ADVISORY.
 
ALEX HAS WOBBLED WEST-NORTHWESTWARD OVER THE PAST 6 HOURS...AND EVEN
BRIEFLY STALLED. HOWEVER...TRENDING THROUGH THE SATELLITE AND RECON
FIXES YIELDS AN AVERAGE MOTION OF 290/06. UPPER-AIR OBSERVATIONS AT
00Z INDICATED MODEST 10-30 METER HEIGHT RISES FROM 700-400 MB
ACROSS THE GULF COAST FROM LOUISIANA TO FLORIDA...BUT ALSO TO THE
NORTHWEST AND WEST OF ALEX ACROSS TEXAS MEXICO TO THE WEST. THIS
MEANS ALEX IS EMBEDDED BETWEEN TO RIDGES AND IN A WEAKER STEERING
FLOW REGIME THAT NONE OF THE MODELS PICKED UP ON IN THE SHORT TERM.
HOWEVER...ALL OF THE GLOBAL AND REGIONAL MODELS ARE CONSISTENT ON
BRINGING A MID-LEVEL RIDGE FROM WESTERN NEBRASKA SOUTHEASTWARD TO
THE TENNESSEE VALLEY DURING THE NEXT 48 HOURS...WHICH SHOULD ACT TO
STEER ALEX ON WEST-NORTHWESTWARD TRACK FOR THE NEXT 24 HOURS AND
THEN WESTWARD ACROSS NORTHERN MEXICO AFTER THAT. THERE HAS BEEN AN
INTERESTING CHANGE IN THE 00Z AND 06 MODEL GUIDANCE WITH THE ECMWF
SHIFTING FARTHER NORTHWARD...WHICH MEANS THIS MDOEL HAS GONE FROM
BEING THE PERSISTENT LEFT-MOST OF THE MODELS TO THE RIGHT SIDE OF
THE MODEL SUITE...AND IT NOW HAS A TRACK SIMILAR TO HWRF. THE
OFFICIAL FORECAST TRACK HAS BEEN SHIFTED SLIGHTLY TO THE RIGHT OF
THE PREVIOUS TRACK BASED ON THE MORE NORTHWARD INITIAL POSITION...
AND REMAINS NEAR THE EXTREME RIGHT SIDE OF THE GUIDANCE ENVELOPE
AND NORTH OF THE MODEL CONSENSUS.

VERTICAL SHEAR IS FORECAST TO REMAIN LIGHT UP UNTIL LANDFALL OCCURS
IN ABOUT 24 HOURS. GIVEN THAT ALEX IS ALSO MOVING SLOWLY OVER SOME
OF THE WARMEST UPPER-OCEAN HEAT CONTENT IN THAT REGION OF THE GULF
OF MEXICO...STEADY STRENGTHENING RIGHT UP UNTIL LANDFALL SEEMS
REASONABLE.  HOWEVER...GIVEN THE RELATIVELY LOW CENTRAL PRESSURE
RECENTLY MEASURED BY THE RECON AIRCRAFT...RAPID INTENSIFICATION OF
AT LEAST 30 KT IN 24 HOURS IS A DISTINCT POSSIBILITY. THE OFFICIAL
INTENSITY FORECAST IS A BLEND OF THE LGEM AND SHIPS MODELS.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      30/0900Z 23.3N  95.1W    70 KT
 12HR VT     30/1800Z 23.8N  96.2W    80 KT
 24HR VT     01/0600Z 24.3N  97.7W    85 KT
 36HR VT     01/1800Z 24.5N  99.6W    35 KT...INLAND
 48HR VT     02/0600Z 24.4N 101.7W    20 KT...DISSIPATING INLAND
 72HR VT     03/0600Z...DISSIPATED INLAND
 
$$
FORECASTER STEWART