TROPICAL CYCLONE FORMATION: NONE
Disclaimer: This site is not affiliated with the National Hurricane Center, Storm Prediction Center, or National Weather Service. ALL forecasts herein are the result of my analysis, and I am solely responsible for the content.
(T. F. “Storm” Walsh III)
For those who have donated to my site, your help has been greatly appreciated. For those not aware, donations to my site help me offset my personal out of pocket expenses…such as some of the model maps you view on here, are only available due to my subscription to the corresponding site. The F5 Data maps I post, also another out of pocket expense (monthly subscription). Updates to software (weather related), and costs for my domain name are also out of pocket to me. To donate, please click the DONATE button to the right. Any help you provide is immensely appreciated! Although it may seem I am not here and working in support of your donation, I have to work my forecasting time around my ever changing work schedule.
CURRENT 2016 ATLANTIC TROPICAL CYCLONE TOTALS:
TOTAL STORMS: 5
INTENSE HURRICANES: 0
StormW’s Seasonal Hurricane Forecast:
TOTAL STORMS: 13-15
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
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.
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.
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.
CIMSS MIMIC-TPW LOOP
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).
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
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
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
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).
Again, 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.
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