EC1:  All things being equal  East Coast hurricanes (hereafter known as   "EC")  will travel along the coast or just off shore (when traveling south to north).   The East Coast  -- as defined by the  area NORTH of Jacksonville FL -- landfalling hurricanes generally fall into three distinct types.

1. Minor Impacts-- Generally Tropical Storms, category 1 & 2 hurricanes that stay off shore  or provide a glancing blow 
   (Felix 1995... Emily 1993... YES I know Emily was a Cat 3 Hurricane).
2. Moderate Impacts  such as Floyd 1999... Bob 1991  as well as large Hurricanes that at one point posed a Major threat but
   for whatever reason  the Threat did not materialize.  (Gloria 1985.. Belle 1976).
3. Major Impacts  such as Donna  1960... Hazel 1954... Diane 1955... Connie 1955... Edna 1954...  and the New England
   Hurricane of 1938 .

EC2. The "BENCHMARK"  for East Coast  Hurricanes  is referred to as 25 N latitude  & 60 West Longitude. In some respects this is similar to the Benchmark for SECL  (Significant East Coast Lows) in the cold months that have to pass near 40 Degrees North & 70 Degrees West.

• Since 1945 ...  73% of all Tropical cyclones  ( Tropical  storms and   Hurricanes)  that pass SOUTH & WEST of the "Benchmark"   either make landfall  on the  East coast  ( N of  Jacksonville) or pass within 200 miles of the coast. 

EC4:  What has distinguished  the well known   Infamous East Coast Hurricanes  is NOT  the  Intensity of the TC  but  a set of SPECIFIC  synoptic scale  (large scale) features  that appear over the   Eastern US and  the Northwest Atlantic Ocean.   All the well known infamous  Hurricanes  of the 30s  40s 50s and early  60s   featured  these specific set of synoptic conditions.

EC5   ALL  EC hurricanes can and DO fall part rather quickly if the forward or Northward speed is under 35 mph.  The slow   forward speed enables the large circulation of a TC  along or Just off the EC to  entrain large amounts of  Dry air which can result in  rapid weakening. Recall Floyd... Gloria... Belle. This  rapid weakening  (and in some cases outright Collapse) of the  TC on the East Coast  is  almost always  missed by  TPC and   other   forecasters

EC6:  For MODERATE  and  MAJOR EC Hurricanes,  the eye should pass WEST of Cape Hatteras through the Pamlico and/or Albermarle sounds.  In almost all cases the passage of the Eye passing East of Cape Hatteras NC means that the Middle Atlantic Coast -- Defined as the area  from Virginia Beach VA - Ocean City MD  - Cape May  NJ - Atlantic City - NYC -- will NOT  experience  true hurricane  conditions.  However a  MODERATE /  MAJOR  impact is still POSSIBLE for  Eastern New England with the eye passage EAST of Cape Hatteras NC..

EC7: . All MAJOR Impact EC hurricanes  have historically featured  two important aspects. The forward speed which has always been 40 MPH or greater  and the Hurricane gets pulled inland by a trough over the Ohio/ and/or Tennessee Valleys.

EC8: . To pull a hurricane inland and create the "IDEAL  inland   track"  for an EC Major Hurricane, there must be something to pull or drive the system inland. In nearly all cases of  the   MAJOR  impact EC Hurricane :

• There  is often a deep Trough  WEST of the Appalachian Mountains  or about   80 degrees Longitude.  IDEALLY Trough axis should be about 85 degrees W. Longitude but this may depend on the size and amplitude of the trough. 

• The  trough should be  of significant size and amplitude so that the Base of the trough reaches as far south as 33-34 degrees   North…preferably as far South as 31-32 degrees N Latitude.   IDEALLY the trough Base should feature a 582 Mb height line south of the Tenn. – Alabama border and

• The timing of the trough.   Once the hurricane reaches the area  WEST of 75 Longitude … and between 25 and 30 North latitude … for a MAJOR EC hurricane… The trough axis should

• The trough should have a Low at 700  MB and 500 MB level that either already exists before the time of landfall or develops within 24 hours of landfall.

• The further south the 700/500 Mb Low is the more likely the chance  that the EC TC will get pull into  trough..

GF 1: Hurricanes that pass SOUTH of Puerto Rico AND have a heading less when 300 degrees   ( 260  270  275  285 degrees) are MAINLY  Caribbean storms... and possibly Gulf of Mexico / South Florida.        

GF2: IF these Hurricanes   (that pass SOUTH of Puerto Rico AND have a heading less when 300 degrees) do indeed become EAST COAST Hurricanes... they rarely become      Moderate or Major  EC   TC impacts  (i.e. David 1979 and Emily 1988).  This is b/c in order for a Caribbean basin TC to   move  into position to affect the  EC it has to cross  Cuba   and/ or  Hispanola.

GF3:  Caribbean tropical cyclones (TC) -- that have a heading  between 260 and 280 degrees do not undergo significant intensification.  This is due to the proximity of the circulation to northern portions of South America which is quite detrimental.  Alama  1974    Joan 1988   Fifi 1974    Carmen 1974. 

  On the other hand  TC  that cross the 60th Longitude  & South of 15 degrees N. Latitude with a 285 - 310 degree  are NOT  affected by the limiting affect of the northern coast of S. America  (Allen 1980 ) and are much more likely to  intensify.

GF4: Conversely Hurricanes that pass south of Puerto Rico But North of  15 degrees Latitude  and are heading 275 to 300 and pass the length of the Caribbean basin often (not always) become category 3 4 or 5 hurricanes.  Gilbert 1988  and Georges 1998 are good examples.

GF5:  Hurricanes which have a satellite picture that show elongated mass to one side often  turn in the direction or alignment of the Clouds mass within 24 hr. In other words…. If satellite pictures show the mass of a westward traveling tropical cyclone elongated to the NW then the Hurricane is likely (8 times out of 10) to turn that way.

GF6: Anticyclones (a ridge of HIGH pressure) at 500 to 200 Mb that located 0 to 70 degrees ( N...NNE...NE...ENE) with respect to the TC  are OFTEN a SIGN  that rapid intensification MAY   occur  ( often.. sign.. may... NOT will).

GF7:  When anticipating a turn of a hurricane... check the winds UPSTREAM of the system. When Hurricane or  synoptic models forecast a TC to turn because of... lets say West winds at 500 MB at 35-45 knots… check this against real time data as the TC approaches. Less wind or winds from a different direction from what the model forecasts is a sign that the forecasted/anticipated turn is not going to happen OR  develop much slower (a ‘wider turn’).

GF8:  The deeper or sharper the trough axis.... the faster & sharper the TC  will turn – i.e. recurvature.  Broad or more shallow troughs often   mean that the TC recurvature  will be slower and take it  more time to affect a change in direction… so expect a slower turn.

GF8:  Troughs that show "separation" or "bagginess"  in the height lines at the Base of the  trough often lead to TC forecasting nightmares. If the trough's base has widely spaced height lines ("bagginess")    with an approaching moderate or large hurricane, then the trough MAY miss the system entirely OR only turn it for a few hours. This bagginess often is found at the base of the trough near 25 or 30 N.Latitude and often involves the standard 594... 588... and 582 Dm height lines.    THIS IS OFTEN MISSED BY HURRICANE AND SYNOPTIC MODELS DUE TO INCOMPLETE UNDERSTANDING OF TC AND MID LATITUDE TROUGHS ON A SYNOPTIC LEVEL

GF9: The base of the trough or trough axis should be with 10 degrees Latitude of the TC to affect re-curvature  (11 degrees Latitude with Tropical Storm).   Larger hurricanes are more resistant to making sharp turns taking a longer time and distance to make them. One of the best ways of determining whether the base of the trough is close enough to the TC is use of water vapor satellite pictures and the movement of the CMB --curbed moisture band (the Black area right behind the bright white areas along a cold front…)

GF10: When a TC is nearing a trough  and is STILL south of 40 degrees N latitude... Once the trough axis is to the NORTH of a TC... IF the TC  has not yet turned to 010 degree or more (for example a heading of  020 degrees...  030 degrees....  045 degrees etc.)... then look for and anticipate hurricane to turn back to the LEFT after the troughs axis has passed East of the TC. 

That is it for now. As time permits I will use maps and diagrams --some from historical events and some not. Let me know what you think.

DH Tolleris
Wxrisk.com