Tropical Storm EMILIA

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TROPICAL STORM EMILIA DISCUSSION NUMBER   5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP062006
800 AM PDT SAT JUL 22 2006
 
DURING THE PAST 6 HOURS...CONVENTIONAL AND MICROWAVE SATELLITE
IMAGERY INDICATE EMILIA HAS EXPERIENCED SOME MODERATE NORTHEASTERLY
SHEAR WHICH HAD DISPLACED THE DEEPEST CONVECTION TO THE SOUTHWEST
OF THE LOW-LEVEL CENTER. HOWEVER...CONVECTION IN THE SOUTHWESTERN
QUADRANT HAS MADE A COMEBACK DURING THE PAST COUPLE OF HOURS...AND
SEVERAL NARROW CONVECTIVE BANDS HAVE ALSO DEVELOPED IN THE
NORTHEASTERN SEMICIRCLE. GIVEN THE RECENT AND EXPECTED CONVECTIVE
REDEVELOPMENT TREND...THE INTENSITY IS BEING HELD AT 35 KT ASSUMING
THAT TROPICAL STORM FORCE WINDS EXIST IN THE SOUTHWESTERN QUADRANT.
 
USING A 12-HOUR TREND...THE INITIAL MOTION IS 335/12. THE ACTUAL
PAST 6-HOUR MOTION HAS BEEN CLOSER TO 15 KT DUE TO EMILIA HAVING
LOST SOME VERTICAL EXTENT WHEN THE CONVECTION BRIEFLY WEAKENED.
HOWEVER...THE VERTICAL SHEAR IS EXPECTED TO DECREASE TO LESS THAN 5
KT BY 24 HOURS...WHICH SHOULD ALLOW MORE CENTRAL CONVECTION AND A
DEEPER VORTEX TO REDEVELOP. THIS SHOULD CAUSE EMILIA TO BE STEERED
MORE WESTWARD BY THE SUBTROPICAL RIDGE LOCATED OVER MEXICO. THE BIG
CONCERN IS EXACTLY WHEN EMILIA WILL BECOME A MORE VERTICALLY DEEP
CYCLONE. IF CENTRAL DEEP CONVECTION DOES NOT REDEVELOP WITHIN THE
NEXT 12 HOURS...THEN A MORE SHALLOW STORM COULD SLIDE TO THE EAST
OF THE OFFICIAL FORECAST TRACK AND MOVE CLOSER TO THE WEST-CENTRAL
MEXICAN COAST... POSSIBLY BRINGING TROPICAL STORM FORCE WINDS VERY
CLOSE TO THAT AREA. THE OFFICIAL FORECAST TRACK IS WELL TO THE
RIGHT OR EAST OF THE PREVIOUS FORECAST...AND IS ALONG THE RIGHT
SIDE OF THE NHC MODEL GUIDANCE ENVELOPE.

THE LOW SHEAR ENVIRONMENT THAT EMILIA IS FORECAST TO MOVE INTO AFTER
24 HOURS WOULD NORMALLY FAVOR SIGNIFICANT INTENSIFICATION. HOWEVER
...LIGHT-MODERATE EAST TO SOUTHEASTERLY 300 MB WINDS ARE FORECAST TO
UNDERCUT THE OTHERWISE FAVORABLE 200 MB OUTFLOW PATTERN...SO ONLY
MODEST STRENGTHENING IS FORECAST...WHICH IS A BLEND OF THE LOWER
GFDL FORECAST AND THE HIGHER SHIPS INTENSITY MODEL FORECAST.
HOWEVER...IF THE 300 MB WIND FLOW REMAINS WEAKER THAN EXPECTED...
THEN EMILIA COULD BECOME A HURRICANE IN 48 HOURS. THE SIZE OF THE
WIND RADII WERE TRIMMED BACK SOMEWHAT SINCE EMILIA HAS NOT YET
INTENSIFIED AND BECOME AS ORGANIZED AS PREVIOUSLY EXPECTED.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      22/1500Z 15.3N 104.6W    35 KT
 12HR VT     23/0000Z 16.4N 105.5W    40 KT
 24HR VT     23/1200Z 17.5N 107.0W    45 KT
 36HR VT     24/0000Z 18.3N 108.2W    50 KT
 48HR VT     24/1200Z 18.9N 109.4W    60 KT
 72HR VT     25/1200Z 20.4N 111.4W    60 KT
 96HR VT     26/1200Z 22.3N 113.8W    50 KT
120HR VT     27/1200Z 24.5N 116.0W    40 KT
 
$$
FORECASTER STEWART
 
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