1650  EDT   JULY 29

Don  looks a little better    this  afternoon.   Nothing  great but   it is clearly   STILL a    TD– tropical depression or bare minimal tropical storm.   Its clear that  DON will not  make it to   Minimal category   1   Hurricane  before landfall .

1000  EDT  JULY  28

DON  looks  lile  crap this morning.  NHC says that it has several centers and none of them had become the dominant one and whenever   that is the case you always have a row the weak  disorganized system.  It  is possible that Don might collapse over the next 6-10  hours…  But if it survives conditions should improve as it approaches the Southern Texas Coast.

1730   EDT   JULY   27

The recon   found a  really   strong  system…  mean sea level pressure  (MSLP)   of 1006 MB and  Max  flight  winds   45 knots  with  Gust to  57 knots.   I dont  know for certain that  NHC will  upgrade this  system  directly to  Tropical  storm  status  at  5pm… but they  should.  Especially given that  this baby  is only  60-72  hours away  from landfall… and the    Hurricane  models  are increasing   this system to  strong   TS   threshold…. and   a few  Hurricane  models  show a  borderline   Min Cate 1   cane at  impact.

The  Forecast  has NOT  changed. The     SEVERE biased  GFDL   model should  be ignored  because that Model has a  strong  NORTH or Poleward  Bias. The   SYNOPTIC  situation  clearly shows  that  there is little chance of   Tropical storm DON  making  landfall   above  Galveston Bay/ Houston.    The  GFS and GFDL  models  once again show the  WEAKEST       ” dome”  over the southest states of any of the   Models  and  because   they  do…  DON  turns    to the NW  much  sooner… and hence an impact   at Galveston Bay.

1400 PM   EDT  JULY 27

 Tropical  Disturbance  90L is  now RAPIDLY   developing … that much  is  clear from the  Midday  IR and  VIS`  satellite  picture.  There is a  pool  of 90 degree F  sea surface temps  in the   Yucatan Channel  that is  also   having some sort of impact.  The recon is  on its  way  and   I would  be stunned if  they did  NOT  find a   Tropical  Depression   later on today.

1900  EDT   JULY  26

We finally have a significant tropical system to focus on here at the end of July.  This system has been  designated  90L by the tropical prediction center (NHC).  As you can see from the satellite pictures this is a fairly well organized system which have developed significantly in last 24 HRS has moved into the western and northwestern portions of the Caribbean Sea.

       
This feature has the potential to develop into a tropical storm and I suppose IF…  if there were to rapidly develop over the next 36 hours it might even make hurricane strength but the odds of strongly against   that happening.  Some of the hurricane model intensity forecast do show in approaching the borderline threshold… which  you can see  here. 

The forecast itself with regard to this potential tropical cyclone is interesting and it shows why one must take a look of the overall pattern as opposed to  JUST  using hurricane models.  Here is the latest forecast package regarding the hurricane models– the 18z JULY 26.  As you can see most of the models are taking this system into far southern Texas and that area certainly could use the rain!!

     
Interestingly for most of the past 90 days there   has been a monster dome in the jet stream centered over Texas and Oklahoma.  This dome of course is one reasons why they have had such an extreme drought over that portion of the nation and  the drought has been sustaining the dome itself so the two features —  the dome and the drought– are locked in some sort of bizarre symbiotic relationship .

The point here is that for the first portion of summer and  probably for most of the 2ND  hald of the Summer and  Autumn the drought and the dome over Texas and Oklahoma is going to prevent most of the tropical cyclone activity in the Gulf of Mexico from hitting Texas.  Anything that moves thru the Western Gulf of Mexico will probably be deflected by this huge dome and be forced to turn its west southwest or even southwest into northern or Central Mexico south of Brownsville.  But at this particular time the pattern has the dome breaking down. 

Over the next few days the dome was going to redevelop over the southeast states –which will cause our region to turn quite hot for three of four days.  But more importantly if tropical disturbance  90L   were to to develop it sets up a pathway for the  90L to follow the dome’s  SW periphery and turn WNW  into the Gulf of Mexico and perhaps make a landfall of north of Brownsville TX.     We can see how this might develop by taking a look of the GFS model at 500 MB  at  36  hrs and  72  hrs and 96  hrs. 

       
In addition over the past 24 hours MSLP  have fallen significantly over the Northern Gulf of Mexico.

Longer term the over all atmosphere across the equatorial regions and the subtropical regions are about to move into a much more favorable pattern.  This image from CPC  shows 200 MB  Vertical Velocities. 

 Without getting too technical the  BROWN areas shows   “sinking air“   and conditions which are hostile to tropical cyclone development  …  while the GREEN  areas show rising motion which enhances the potential of any tropical disturbance into becoming a tropical cyclone.  In this image the features move from left to right so as you can see right now over the Gulf of Mexico the Caribbean and the tropical Atlantic  is in  BROWN areas  or the sinking year.   But as you can see… coming in from the Pacific and even as far west as China …there is a large expanse of area rising motion which is represented by the GREEN  regions.  Over the next week this energy will begin to move into the Gulf of Mexico and Western Caribbean and then rapidly spread into the entire tropical Atlantic region at the same time as the counter moves into August. 

Do not be surprised if we see a significant burst of activity in the tropical Atlantic during the first two weeks of August.  La cities

MMS11

31  OCT   2010  1155 EDT/ 1555  Z

Just like the overall pattern across the northeast US  has become rather stormy with intervals of rather tranquil weather in between  during  OCT   2010…  we  are seeing a similar  sort of pattern over western and central Europe.

We actually end up seeing this sort of thing fairly often.    Just like on  the West coast where the weather is often the exact opposite is on the east coast…  we see the same sort of thing between the East coast of the  CONUS  and Western / central  Europe.  There is a specific reason for that  – it is  not just weather coincidence.

 The West coast  is  3000- 3300 miles away and that  just happens  to be  most  common  distance between  the wavelenghts   of   Ridges and  troughs at that latitude in  the   world.   This is also  the case   betwen the East coast and   western  half of Europe.

Over the past few weeks   there  have been a  number of significant troughs ….some of them quite deep in terms of amplitude over Western Europe  which has provided for significant rains.    But these   longwave   troughs have been so deep that the southern end or southern base of the trough have separated from the main flow. This results in   a closed   500 MB  Low  that is   ” cutoff”    from  the main flow.    Over the past few  weeks this  has been happening  alot   Spain  & western   Mediterranean.   This  500 MB low then  meanders across western and central Mediterranean into the southern Balkans  and Turkey.

This means  that the Ukraine  and    southwest Russia  which is still trying to recover from a deadly heat and drought of the past summer   has not   been seeing   good  rains. Indeed  that IS  the case  with this current system.    The Sunday   weather maps  hvae a  deep 500   short  wave trough  with a fairly strong area of low pressure southwest of Cornwall   England that is approaching the Bay of Biscay inland  at 981  MB.     This system over the next two or three days ….will drop through France and and into the central Mediterranean while the northern end  the jet stream is carrying in the next strong system well north of Scotland  and  headed towards  Norway.

The Low that moves into the Mediterranean Monday & Tuesday  is much weaker than the Low  coming into Norway so has a result   the  Northern Jet stream   leaves the southern Low behind .  If the Southern System were to continue to move east it could provide some rain into the southern portions of the Ukraine and into  sw  Russia but the model data clearly shows that does not happen.  The weak   Mediterranean low meanders over the eastern Mediterranean and then finally falls apart.

  Far more important however it is the the depiction of a monster storm for inland and Western  Europe   NOV  7-8.  The 0z  Euro has this Low at  953 mb over far southwest England on the evening of the  11/8. 

Why does the European model developed  this system into a  monster  North  Atlantic    storm  that  reaches   category 3 hurricane intensity ?

The KEY  appears to be a the development of the    coastal storm over the East coast  of the   CONUS   and the monster trough  in the   Jet stream  NOV  5-6-7  and hurricane Tomas.   The deep East coast trough causes a strong ridge to form in the western and Central Atlantic Ocean but that ridge is fed  or  enhanced  by the heat  from  hurricane Tomas as it moves into the western portions of the north Atlantic after day 6-7.      This  Super powerful ridge in the north Atlantic builds towards the southern tip of  Greenland which forces the next piece of energy in the polar jet to drop rapidly the southeast towards Ireland and England as it undergoes rapid intensification.  

  This results in the     European   model   developing   this      super  Bomb    Low for western European  UK Low.