2000 EDT   5  JULY   STARDATE  201207.05

Back at the end of JUNE I made a post about the potential for the severe drought   in  the Midwest  and Deep South …which has  now spread to much of the country… coming to an end  sometime after the July 4 holiday.  Or at  least being significantly diminished.  The bases of that forecast was to a  large degree made on the  projected movement  of the current MJO.  On  JUNE 23  the MJO was on Phase 1 …  moving through Phase 2.  In   late JUNE and  early JULY ….Phase 2 favors a hot and dry pattern for the Midwest.   But  I  thought the MJO  would reach  Phase 3  after JULY 5  — in  the  month of JULY  Phase 3  favors above normal rainfall across most of the Midwest and the Northeast.
That weekend  of JUNE 22-23-24   with the MJO in phase 1   there were some areas of moderate rain in the Midwest .   However the  MJO  in Phase   2  stalled  at the end of the month and  into  early July which meant a prolonged interval of more hot and dry conditions over the Pains …the Midwest …and the East Coast.  As all of us have seen over the last several days that is indeed exactly what the weather pattern has reflected– worsening drought and more extreme heat with many many locations seeing day after day of 95-105°  max temperatures.  This image shows the current MJO phase  over the last 40 days out we can clearly see it move through Phase 1   and  2 .   Notice that all around JUNE 23  the  MJO    did a  ” stall”    or  little  loop which slow down its progression through phase 2 and into phase 3.   Thus my forecast for a wetter  and somewhat cooler  pattern    was going to be delayed.

However  the  new MJO forecast  Models do show that the current  MJO   is  going to make it into phase 3 pretty shortly…. and as I have stated that is significant  because    Phase  3  in the month of July  strongly correlates to a  wet pattern over the Midwest and the East Coast.    Here we have the  MJO   forecasts  from the   ECWMF    the Ukmet  and the   euro ensembles.    That being said many of these models then  EITHER        A)  weaken the MJO impulse and drop it into the “circle of death”      ( which represents the weakening of  the MJO impulse to the point where it no longer impacts the weather patters)      or    B)  RETOGRADE  the MJO  back into   Phase 2.

However  the MJO doesn’t seem to want to cooperate   with the forecast models.  Over the past several days the various models used to forecast the MJO  have been consistently showing  this  retrogression   yet the MJO  keeps moving forward and closer and closer to phase 3.
But decides  the MJO …there  is more and more evidence showing that the delayed El Nino event is finally beginning to Kick in.  This image shows the    current SOI values   (SOI   is a index  used   to  assess atmospheric  and ocean water  temperatures that bring about either a   El Nino  La Nina  or  Neutral conditions).  Whenever the 30 day average  of the SOI  drops below the value of  -8.0  El Nino conditions always develop.  The current  value is   -12.9 so as you can see we are past the threshold by a significant amount.

Interestingly .. if you look at the SOI  chart  you will see that during March and April  it  seemed  that  the SOI   was dropping steadily and that by the time we reached the early Summer  the   El Nino would be under way.  Indeed many seasonal forecast were premised on that idea.    However in  MAY 2012  the SOI  had a “spike”   which drove the  SPI  values  briefly back into positive territory.  This delay the onset of El Nino conditions and allow the  current pattern from the Winter and Spring to continue into the early Summer….  which aggravated the developing drought conditions  and that in turn enhance the   very warm pattern   of the  Winter  and  Spring into an   very hot one for the  first half of the summer of 2012.
In addition    ocean where temperatures  in the ENSO  regions  are rapidly warming  which is another strong sign that the  El Nino is beginning to  kick in.

If we focus a little closer to home…  We can see the current atmosphere a pattern over North America.  This image represents the European model from Thursday afternoon and we can clearly see the enormous heat dome covering the Plains  and the Midwest.

However important changes are going to take place starting this weekend which will drive the heat dome back to the West coast.  If you have any friends  or relatives   on  the West Coast they have had a pretty cool Spring and early Summer but that is  about to change.  The development of a large upper low over Eastern Canada will begin to cause the pattern to change this weekend.  This Upper Low will establish   a deep trough in the jet stream over the Great Lakes/ Midwest and  the  Northeast   which will force the   Heat Dome   back into the West coast and the Rockies .   This development of a major trough to form in the jet stream over the Great Lakes  and    eastern Canada  will drive  a pretty strong  surface  cold front   from North to South JULY  7-8-9   reaching into the Gulf coast states and the southeast by JULY  9.

As the cold front drive south it piles up the hot temperatures so that the day before the cold front arrives …many areas  over the  the lower Middle Atlantic states could be the hottest  temps we seen in many years.  It is possible that the all time high does temperature on record in Richmond could fall !  The NAM  Model on Thursday afternoon   is forecasting a Max temperature on Saturday of 107°temperatures and as you can see many areas   see temps of 105+ over  VA   and NC.

By July 9 the cold  front is going to stall along the Gulf coast and over the Southeast states and it will become a focusing mechanism for developing a lot of rain …   NEXT WEEK   July  8-15 …  for areas that really need it –   MS  AL  TN   GA  SC  NC  southern VA  and far southern WVA.  Some of the rain will probably get into northern  VA    as well as    central and eastern    MD  DE and southern NJ at times.. but  the vast majority of the widespread significant or heavy rains will fall over the  Deep south …into southern Virginia .

This first image shows the  12z GFS   from JULY 5…   in the 6-10 day with a map on the LEFT  being the operational Run — note the  6.46″  bulls eye over  northwest   SC and  southwest  NC in the    high terrain.   The map on the right   is the GFS ensemble mean  rainfall forecast.

This next image shows the rainfall forecast  from the 12z GFS Thursday afternoon run  for the 11-15 day   time frame . Once more the map on the left side is the operational GFS run and the map on the right side is the GFS  ensemble run.   As you can see both models/ map show additional significant rain over the Tennessee Valley and the Middle Atlantic states but also we see good rains getting into portions of the drought areas in the Midwest.

Finally here is the 18Z  GFS   ENSEMBLE model  runs… for the  6-10 day on the left and the 11-15 day on the  right.  The 18z GFS is even wetter across the deep south into North Carolina central and Eastern Virginia Eastern Maryland into Southern New Jersey with a large area of 2-4″  rains.    Again in the 11-15  day the front is still  bringing  good rains to the  Middle Atlan tic and the   Midwest areas.

  SUMMARY  even though the next two days  are going   to be very tough for everybody and the Midwest …the Deep South and the East Coast  …the  Heat Wave  IS going to come to an end.  The pattern shift starts this weekend.  Next week  over all of the Middle Atlantic — but a specially over the lower Middle Atlantic  ( VA MD DE)   and all Southeast  states  (NC    SC  GA) and Gulf coast  states ( LA  MS  AL    southern TN)   will feature  above normal rainfall and cooler temperatures because of the overcast skies and the numerous large areas of showers and thunderstorms .  Many areas will see as much as 5 inches a rain over a five day but some of the locations over higher terrain— such as    Northern GA   far eastern TN  western  NC    southwest  VA   could see  up to 8 inches.  The Midwest will see temps   in the 80s  as will the Northern Middle Atlantic and New England states.