TROPICAL WEATHER FORECAST SYNOPSIS…ISSUED AUG. 08, 2016…4:30 P.M. EDT

TROPICAL CYCLONE FORMATION: NONE

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(T. F. “Storm” Walsh III)

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CURRENT 2016 ATLANTIC TROPICAL CYCLONE TOTALS:

TOTAL STORMS: 5
HURRICANES: 2
INTENSE HURRICANES: 0
U.S.LANDFALLS: 2

StormW’s Seasonal Hurricane Forecast:
TOTAL STORMS: 13-15
HURRICANES: 6-7
INTENSE HURRICANES: 3-4

Good day everyone!

Dr. Phil Klotzbach issued his Aug. 04, 2016 Tropical Atlantic Seasonal Hurricane update.  His thinking is unchanged from July 01.  Dr. Klotzbach still indicates 15 named storms, 6 hurricanes, and 2 intense hurricanes (including Alex through Earl).

THE TROPICAL METEOROLOGY PROJECT CSU
http://tropical.colostate.edu/

Based on my uncertainty at the moment regarding further SAL outbreaks, I have decreased my seasonal forecast slightly.

The area of low pressure that was associated with a surface trof moved onshore over the eastern FL. Panhandle early yesterday.  The actual low is now centered over central Georgia.  Current steering indicates a south to north flow at the moment, which coincides with the northward slow motion of that low.  However, visible and RGB satellite loop imagery indicates the low may now be starting to move slowly westward, which would be the beginning of the semi-cyclonic loop I spoke of, based on forecast steering layers maps.  This westward motion is in my forecast, based on current forecast steering, which would begin to push rain with it, and may be the reasoning behind the WPC and global models QPF as of earlier this morning.

GOMEX SATELLITE LOOP IMAGERY
avn-lgomex

rgb-lGOMEX

The NHC has dropped this from the TWO, as no further development is expected.  However, I am not totally certain at the present that this whole thunderstorm complex may be feeding back on itself.  Visible and RGB satellite loop imagery in the last 2 frames of the loop, seems to display some mid level rotation over the FL. Big Bend area.  Though probably only temporary, I am going to continue to look at this area, as there is a diffluent flow over the area at the moment, upper level divergence has increased somewhat over the past 6 hours, and an outflow channel has been established on the eastern periphery of the thunderstorm complex.

WPC QPF MAPS 5 AND 7 DAY
p120i

p168i
The area of disturbed weather east of FL. near 70W, has been waxing and waning in convection since early this morning. The NHC has also dropped this area from the TWO.  Analysis of the current zonal wind shear forecast indicates upper level winds to become more conducive in about 6-12 hours.  However, this window of improved upper level winds is only forecast to last about 6-8 hours.  Based on this, I am not expecting development out of this, but will keep an eye on it out of respect for the amount of TPW associated with the area.

EAST COAST SATELLITE LOOP IMAGERY
avn-leastus

CIMSS MIMIC-TPW LOOP
latest72hrs
Current motion appears to be toward the NNW.  Now, here is where motion gets tricky…Depending on whether this increases or decreases forward speed will determine where this area will wind up.  Based on the update forecast steering maps, the ridge is forecast to push toward the west.  So, I have two scenarios I will lay out…this either begins to move more toward the north over the next 12-18 hours, which would most likely for a re-curve.  Should this continue to move toward the NNW without any change by then, this area could cross around SC/NC in about 36 hours.

Elsewhere, the tropics are once again quiet.  The wave that was close to the African coast, has pretty much become discernible, as the TPW surge that appeared in the MIMIC-TPW loop yesterday, has been slammed by some drier air moving SE from the extreme NW coast of Africa, near the Canary islands (see TPW loop above).

METEOSAT LOOP IMAGERY
avn-lmeteosat

Dust this season for some reason has seemed (at least in my opinion) to be more prevalent.  The current NASA Aerosol/Dust forecast continues to display dust in the 5-10 day forecast.  Having read most of the article I posted yesterday regarding the role of the SAL, analysis of this product doesn’t indicate very heavy amounts of particulates south of 12N, and indicating some breaks in the dust near the African coast.  I will post the article link again, to which you may wish to read as it’s a very interesting article.  So, at the particular moment, I have some uncertainty as to whether or not this dust forecast will be too detrimental as we enter the ramp up period according to climatology.  My reasoning behind this is, both information from NASA and the GFS global model indicate some pretty moderate TPW values forecast or the same 5-10 day period (approx.).  Again, remember the TPW Earl was embedded in.  If you remember, Earl began as a wave in the EATL and traversed the entire Atlantic basin without incident, and pretty much void of any convection.  However, catching up to and becoming embedded in the TPW area we witnessed (in my previous forecasts), the wave eventually slowed enough and came under favorable upper level and OHC conditions.  Albeit we did note dry air surrounding pretty much the western and northern periphery, the TPW content allowed for Earl to work with enough moisture to prevent dry air intrusion.  Based on that premise, I do not believe we can count the season as “out”.  With that, here are two thoughts on this…I’m either going to be right, or I’m gonna bust.  I have provided links for you, to have a better understanding of what TPW (Total Precipitable Water) is:

ATMOSPHERIC WATER VAPOR
http://www.remss.com/measurements/atmospheric-water-vapor

PW (from the Weather Prediction…Haby Hints):

1. What is PW?

PW stands for Precipitable Water. It is a parameter which gives the amount of moisture in the troposphere.

2. How is PW determined?

PW is determined by taking all the mass of water vapor in the troposphere and depositing it on the earth’s surface. The depth of moisture that would be on the earth’s surface is the PW value. The mass of water vapor is determined by the dewpoint (saturation mixing ratio) of the air integrated over the troposphere. Higher dewpoints lead to higher PW values, especially if the relatively high dewpoints extend through a significant vertical depth. The scale below gives an indication of the moisture content of the troposphere via PW.

0.50 inches or less = very low moisture content
0.50 to 1.25 inches = low moisture content
1.25 to 1.75 inches = moderate moisture content
1.75 to 2.00 inches = high moisture content
2.00 inches or above = very high moisture content

AMS JOURNAL PAPER ON RE-EVALUATING THE ROLE OF THE SAL
http://journals.ametsoc.org/doi/full/10.1175/2009MWR3135.1

CURRENT SAL PRODUCT FROM CIMSS
truecolZ-1

splitE-1

CURRENT NASA AEROSOL/DUST FORECAST MAPS 5 AND 10 DAY
nasa_dust_atlantic_21
nasa_dust_atlantic_41
NASA CURRENT TPW/PWAT FORECAST MAPS 5 AND 10 DAY
nasa_pwat_nafrica_21

nasa_pwat_nafrica_40

GFS TPW FORECAST 72 HOURS AND 228 HOURS
gfs_pwater_westafr_13

gfs_pwater_westafr_39

The NASA and GFS and ECMWF indicate the sub-tropical ridge to move west, and weaken from 1030 mb to a 1026-1024 mb average within 7-8 days from this morning

NASA MSLP FORECAST
nasa_mslp_atlantic_34
This could be a trigger as we saw previously when the ridge weakened and moved west, in that the easterlies slow down and allow for heat to build and for surface convergence to take place.

With all that said, the early a.m. runs of the GFS and ECMWF indicate a lowering of the 500 mb pressure heights near Africa/CATL in approximately 5-6 days.  GFS also seems interested in the Caribbean.  Albeit the areas do not appear large, the aerial coverage of the height falls are not unlike what Earl looked like when the ECMWF initialized him.  These areas would be indicative of the increase in the TPW.  The ECMWF however does not maintain a closed low, but maintains two tropical waves (I have the wave axis’ in red).

GFS 500 MB NORMALIZED ANOMALIES
gfs_z500_sig_catl_17
gfs_z500_sig_catl_23

gfs_z500_sig_catl_29ECMWF
ecm_z500_anom_catl_5

ecm_z500_anom_catl_7Again, based on rainfall over Africa so far, most systems will most likely come off Africa at a lower level (10-12N), as the current 5 and 10 day total precipitation forecasts indicate rainfall to remain below the Sahel region of Africa. 

ECMWF EPS 5 AND 10 DAY AFRICA RAINFALL TOTALS
eps_tprecip_c_westafr_21

eps_tprecip_c_westafr_41

GFS 5 AND 10 DAY AFRICA RAINFALL TOTALS
gfs_tprecip_westafr_21

gfs_tprecip_westafr_41

Elsewhere, Tropical Storm formation is not expected during the next 5-7 days

T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST /SEVERE WEATHER SPECIALIST
MEMBER WEST CENTRAL FLORIDA AMS
CoCoRAHS OBSERVER

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About palmharborforecastcenter

I am a Tropical Forecast meteorologist, providing hurricane forecasts during the Atlantic Hurricane Season. I retired from the U.S. Coast Guard in July of 2001. Meteorology became my passion in high school, and I have continued my educational background in meteorology since 1996, when I undertook the study of Tropical Meteorology. While working toward my degree, I had to unexpectedly withdraw from college due to my oldest sons medical reasons. I do however, meet the educational criteria of the AMS to be recognized as a meteorologist. Studies include, but are not limited to the Navy Aerographers Mate course, Naval METOC meteorology course, Meteorology 2010 Sophomore level course while attending St. Petersburg College, Clearwater, FL., Basic Forecasting course for operational meteorologists from Rapid WX, meteorology institute, a four month meteorological internship, and extensive research on numerous meteorological topics such as the MJO, NAO, satellite imagery interpretation, etc. I have been forecasting Tropical Weather (Tropical Storms and Hurricanes) since 1996, with my main client being three different Coast Guard Commands.
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2 Responses to TROPICAL WEATHER FORECAST SYNOPSIS…ISSUED AUG. 08, 2016…4:30 P.M. EDT

  1. dellamom says:

    Thank you, Storm, for all your hard work.

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