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TTAA00 KNHC 191449
HURRICANE NORA DISCUSSION NUMBER  13
NATIONAL WEATHER SERVICE MIAMI FL
8 AM PDT FRI SEP 19 1997
 
DEEP CONVECTION HAS BECOME NEARLY NON-EXISTENT IN THE NORTHWEST
SEMICIRCLE AND THE CENTER...WHILE EASY TO LOCATE...DOES NOT APPEAR
QUITE AS WELL-FORMED THIS MORNING.  DVORAK CLASSIFICATIONS HAVE
DROPPED OFF A LITTLE AND THE INITIAL WIND SPEED IS NOW ESTIMATED TO
BE 85 KT.  AS NOTED IS THE PREVIOUS DISCUSSION...IT IS POSSIBLE THAT
THIS WEAKENING IS RELATED TO THE PROLONGED SLOW MOVEMENT OF
NORA...KEEPING THE HURRICANE OVER RELATIVELY COOL UPWELLED WATERS.
THE HURRICANE REMAINS NEARLY STATIONARY.
 
THE UPPER LOW TO OVER THE BAY OF CAMPECHE HAS MOVED A LITTLE
NORTHWARD DURING THE PAST 24 HOURS.  A DRY ANTICYCLONE AND RIDGE ARE
ORIENTED FROM WSW TO ENE TO THE NORTH OF NORA.
 
ONCE AGAIN THE INITIALIZATIONS OF THE MRF AND AVN ARE SUSPECT.  THE
00Z MRF AND 06Z AVN CONTAIN NORA AND A SECOND...UNSUBSTANTIATED
VORTEX...TO THE SOUTHWEST OF THE HURRICANE.  ON A BROADER
SCALE...THE MODELS SHOW THE HIGH CENTER MOVING TOWARD THE EAST OVER
THE NEXT 72 HOURS.  THEY ALSO SHOW A WEAKNESS OR CUT-OFF LOW STAYING
BEHIND THE WEST COAST TROUGH...TO THE WEST OF BAJA CALIFORNIA.  THE
MRF MOVES THE COMBINED MODEL REAL/SPURIOUS CIRCULATION SLOWLY TOWARD
THE NORTHWEST BETWEEN THESE FEATURES.  THE OFFICIAL FORECAST AND
TRACK MODELS...NOGAPS AND THE UKMET IN GENERAL ALSO SHOW NORA
GRADUALLY APPROACHING THE SOUTHERN PART OF BAJA CALIFORNIA.  GIVEN
THAT THE HURRICANE IS CURRENTLY STATIONARY AND THAT UPPER-LEVEL LOWS
ARE NOT OFTEN CORRECTLY FORECAST...THE LONG-TERM TRACK OF NORA
REMAINS UNCERTAIN.

NORA COULD RESTRENGTHEN WHEN IT MOVES AWAY FROM THE LOCAL COOL POOL
OF UPWELLED WATERS. 
 
RAPPAPORT
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     19/1500Z 14.4N 104.1W    85 KTS
12HR VT     20/0000Z 14.7N 104.3W    85 KTS
24HR VT     20/1200Z 15.6N 105.1W    90 KTS
36HR VT     21/0000Z 16.9N 106.2W    90 KTS
48HR VT     21/1200Z 17.8N 107J.1W    90 KTS
72HR VT     22/1200Z 19.5N 108.5W    90 KTS