Image Department Meteorology
Meteorology_Home Weather_Server News/Seminars
People
Research
Academics Application Contact_Us

Hawaiian_Weather
US_Mainland_Weather
Tropical_Weather
Satellite_Imagery
Radar_Imagery
Marine
Numerical_Models
LAPS
Forecasts
Observations
Archive
Links Disclaimer
Space
SOEST_Home
University_of_Hawaii_Home

 859 
 WTNT45 KNHC 262035
 TCDAT5
 TROPICAL STORM DANNY DISCUSSION NUMBER   2
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL052009
 500 PM EDT WED AUG 26 2009
  
 SATELLITE IMAGERY AND REPORTS FROM AN AIR FORCE RESERVE HURRICANE
 HUNTER AIRCRAFT INDICATE THAT DANNY IS VERY DISORGANIZED AT THIS
 TIME.  THERE IS NO ORGANIZED CONVECTION NEAR THE CENTER...AND THE
 STRONGEST WINDS ARE IN A BAND 100-150 N MI FROM THE CENTER OVER THE
 NORTHERN SEMICIRCLE.  THE AIRCRAFT REPORTED 1500 FT FLIGHT-LEVEL
 WINDS OF 49 KT AND ESTIMATED SURFACE WINDS OF 40-45 KT FROM THE
 SFMR.  BASED ON THIS...THE INITIAL INTENSITY REMAINS 40 KT.  THE
 AIRCRAFT JUST REPORTED A CENTRAL PRESSURE OF 1007 MB.
  
 THE INITIAL MOTION IS A SOMEWHAT UNCERTAIN 300/10...UNCERTAIN
 BECAUSE THE STORM SEEMS TO BE DECELERATING...AND THE CENTER MAY BE
 OCCASIONALLY RE-FORMING DUE TO CONVECTIVE BURSTS.  THERE IS NO
 CHANGE TO THE PREVIOUS FORECAST REASONING.  DANNY IS NORTH OF A
 MID/UPPER-LEVEL LOW CENTERED OVER HISPANIOLA AND SOUTHWEST OF A
 MID/UPPER-LEVEL RIDGE CENTER EAST OF BERMUDA.  THIS PATTERN SHOULD
 STEER DANNY GENERALLY NORTHWESTWARD FOR THE NEXT 24 HR OR SO. 
 AFTER THAT...A MID/UPPER-LEVEL TROUGH SHOULD DEVELOP OVER THE GREAT
 LAKES...WITH A MID/UPPER-LEVEL LOW OVER THE GULF COAST STATES
 MOVING EASTWARD OR NORTHEASTWARD.  THIS EVOLUTION SHOULD CAUSE
 DANNY TO TURN NORTHWARD AND THEN RECURVE INTO THE WESTERLIES. 
 WHILE THE MODELS AGREE ON THE SCENARIO...THERE IS STILL SIGNIFICANT
 UNCERTAINTY AS TO WHAT LAND AREA DANNY MAY AFFECT.  THE ECMWF...
 UKMET...AND CANADIAN MODELS FORECAST THE CENTER TO PASS NEAR CAPE
 HATTERAS AND THEN MAKE LANDFALL IN NEW ENGLAND.  THE GFS AND GFDL
 SHOW THE CENTER PASSING EAST OF HATTERAS AND THEN PASSING NEAR OR
 OVER CAPE COD.  THE HWRF AND NOGAPS...AS WELL AS THE CORRECTED
 CONSENSUS MODELS...SHOW THE CENTER PASSING EAST OF CAPE COD AND
 NEAR OR OVER NOVA SCOTIA.  OVERALL..THE GUIDANCE ENVELOPE HAS
 SHIFTED SLIGHTLY TO THE EAST SINCE THE LAST ADVISORY.  THE NEW
 FORECAST TRACK IS ALSO SHIFTED SLIGHTLY TO THE EAST AND LIES NEAR
 THE MIDDLE OF THE GUIDANCE ENVELOPE.  THE FORECAST TRACK IS ROUGHLY
 PARALLEL TO THE U. S. EAST COAST...AND ANY DEVIATION FROM THE TRACK
 COULD MAKE A LARGE DIFFERENCE IN WHAT AREAS GET IMPACTED BY DANNY. 
 THEREFORE...IT IS IMPORTANT NOT TO FOCUS TOO MUCH ON THE EXACT
 FORECAST TRACK.
  
 THE INTENSITY FORECAST REMAINS PROBLEMATIC.  WATER VAPOR IMAGERY
 SHOWS UPPER-LEVEL LOWS NORTH AND SOUTH OF DANNY CONNECTED BY A
 CYCLONIC SHEAR AXIS.  THIS IS NOT A IDEAL PATTERN FOR
 STRENGTHENING...AND IT MAY TAKE 24 HR OR MORE FOR THE ENVIRONMENT
 TO BECOME MORE FAVORABLE.  IN ADDITION...THE CURRENT STRUCTURE OF
 THE STORM FAVORS SLOW STRENGTHENING AT BEST.  BASED ON THIS...THE
 INTENSITY FORECAST CALLS FOR SLOW STRENGTHENING FOR THE FIRST
 36 HR.  IT THEN SHOWS A FASTER STRENGTHENING FROM 36-48 HR AS
 CONDITIONS BECOME MORE FAVORABLE.  AFTER 48 HR...STRONG UPPER-LEVEL
 SOUTHWESTERLY WINDS ASSOCIATED WITH THE EASTERN U. S. TROUGHS ARE
 EXPECTED TO CAUSE INCREASED SHEAR AND INITIATE EXTRATROPICAL
 TRANSITION...WHICH COULD START BEFORE DANNY REACHES THE LATITUDE OF
 NEW ENGLAND.  THE INTENSITY FORECAST CALLS FOR DANNY TO REACH 65 KT
 IN 72 HR...THEN BECOME EXTRATROPICAL BY 96 HR.  THE INTENSITY
 FORECAST IS IN BEST AGREEMENT WITH THE SHIPS AND LGEM MODELS. 
 HOWEVER...IT REMAINS WEAKER THAN THE FORECASTS OF THE GFDL AND
 HWRF.
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      26/2100Z 25.2N  71.2W    40 KT
  12HR VT     27/0600Z 26.0N  72.5W    40 KT
  24HR VT     27/1800Z 27.1N  73.8W    45 KT
  36HR VT     28/0600Z 28.7N  74.5W    50 KT
  48HR VT     28/1800Z 31.1N  74.5W    60 KT
  72HR VT     29/1800Z 38.5N  71.5W    65 KT
  96HR VT     30/1800Z 47.5N  63.5W    60 KT...EXTRATROPICAL
 120HR VT     31/1800Z 53.1N  48.0W    45 KT...EXTRATROPICAL
  
 $$
 FORECASTER BEVEN
  
 
Return to the Tropical Systems Page for DANNY

Back to main Tropical Weather page




This page is maintained voluntarily by the MKWC and the UHMET faculty, staff, and students.
It was last modified on: Thu, Jul 23 2020 - 2003 UTC
Send comments to: Ryan Lyman