INVEST 92L / TROPICAL WEATHER OUTLOOK FORECAST SYNOPSIS…ISSUED AUG. 05, 2021…11:40 A.M. EDT

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(T. F. “Storm” Walsh)

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Greetings to everyone!
Please be aware, even though I do not post every night, rest assured I am continuously monitoring various areas for any significant weather.  I will be taking Sundays off (family time), unless we have active systems that may be posing a threat (i.e. Tropical, Winter Weather, Coastal Storms, etc.).
STORM WALSH PRE-SEASON FORECAST
TOTAL NAMED STORMS: 17 – 20
TOTAL HURRICANES :        7 – 9
MAJOR HURRICANES:       4 – 5

AVERAGE HURRICANE SEASON:
TOTAL NAMED STORMS: 14
TOTAL HURRICANES:         7
MAJOR HURRICANES:       3

2021 SEASON TOTALS:
TOTAL NAMED STORMS: 5
TOTAL HURRICANES:       1
MAJOR HURRICANES:     0

TOTAL U. S. LANDFALLS: 3

The following is the list of storm names for the 2021 Atlantic Hurricane Season:
Ana Bill Claudette Danny Elsa Fred Grace Henri Ida Julian Kate Larry
Mindy Nicholas Odette Peter Rose Sam Teresa Victor Wanda
As a storm becomes named, I will be marking it in bold red to keep track of the activity for this Atlantic season.

Please note..when we are dealing with multiple systems, they will be listed in order as to the greatest threat to land or the U. S. , to the least threat.

Analysis of satellite loop imagery this morning indicates a tropical wave exiting the African coast.  The NHC has this in the 5 day graphical tropical weather outlook, along with another area in the CATL that was near 45W this morning.  However, the current initialization of the African feature (now designated INVEST 92L), is a little confusing, as ASCAT data doesn’t indicate the circulation to be close to the coast, but rather a little further west.  This may lead to a center relocation, but will remain to be seen.  Another possibility is the ASCAT may reflect what was 91L, however the ATCF website has dropped 91L, no longer issuing guidance, even though it is showing up on some guidance maps.  ASCAT was current as of 1300Z (9:00 a.m. EDT) this morning.  Let’s give this about 24 hours and actually see what happens.  ASCAT data did not indicate any circulation near 45W.  Visible satellite loop imagery indicated this particular area is under a very stable environment based on stratocumulus clouds over the area.  One thing you will notice, water vapor imagery still shows a large area of dry air (orange color) over a portion of the Atlantic, however the area of the MDR from 30W, eastward to over Africa has moistened up.  This is most likely attributed to the MJO continuing to move toward phase 1.
NHC 5 DAY GRAPHICAL TROPICAL WEATHER OUTLOOK (GTWO)LINKED
two_atl_5d0
two_atl_5d1
WEATHERNERDS SATELLITE ANIMATIONS
27029889IR
WATER VAPOR LOOP
27029889WV
VISIBLE SATELLITE IMAGE (YELLOW AREA OF NHC MAP)
GOES16_1km_vis_202108051405_7.00_26.25_-65.25_-32.75_vis1_ltng16_hgwy_warn_latlon_weathernerds
1300Z ASCAT PASS
WMBas124

AS of the 12Z ATCF BTK report, the following was available on INVEST 92L:
8:00 AM EDT Thu Aug 05

Location: 11.5°N 10.5°W
Moving: W at 22 mph
Min pressure: 1013 mb / 29.91 in
Max sustained: 25 mph

INVEST 92L is currently moving toward the west.  Based on forecast steering analysis, I expect a general westward, to just north of due west motion to continue for the next 48- 72 hours.  Thereafter, it appears at the moment that a weakness develops in the subtropical ridge, and a more WNW motion ensues, eventually becoming NW.  This could allow INVEST 92L to recurve.  Right now, I tend to agree with this scenario, however given that the system is not organized and has just been initialized, guidance this early should be considered low confidence.

The NHC is currently designating a MEDIUM (60%) probability of INVEST 92L developing into a cyclone during the next 5 days.  Based on my analysis of forecast wind shear maps, and forecast upper level moisture, and given the current uncertainty of where exactly the center is located, and where exactly it will be located in 24 – 36 hours, I feel this probability may be a little generous.  Wind shear and upper level forecast winds indicate a breif period where upper level winds may become slightly more favorable, but remain marginal at the moment in the forecast.  The zonal wind shear forecast currently indicates easterly shear may affect the system over the next 5 days.  The 200 mb streamlines forecast does not indicate any real type of outflow per se during the next 5 days.  Analysis of TPW and forecast relative humidity values does indicate high TPW for surface moisture, however forecast RH values at 500 mb indicates dry air may be a problem at this level as the 500 mb forecast map indicates dry air intrusion.  Based on this, I am going to monitor INVEST 92L and the area ahead of it for any changes to forecast atmospheric conditions during the next 24 – 36 hours, before making a solid forecast on development or future strength.  As of now, I have a little lower confidence in short term development, and the ECMWF and GFS do not really indicate development at the moment.  Even though the MJO is swinging in a favorable direction, and vertical instability continues to increase over the MDR, we are just not quite there yet, but the stage is being set.
CURRENT VERTICAL INSTABILITY (BLACK LINE INDICATES CLIMATOLOGY)
ts_al_tat_THDV
ECMWF AND GFS MSLP NORMALIZED ANOMALIES ANIMATION
ecmwf-deterministic-exatl-mslp_norm_anom-1628121600-1628121600-1628726400-40
gfs-deterministic-exatl-mslp_norm_anom-1628143200-1628143200-1628748000-40
TPW FORECAST
ecmwf-deterministic-exatl-pwat-1628121600-1628121600-1628748000-40
500 MB RH FORECAST
ecmwf-deterministic-exatl-rh500-1628121600-1628121600-1628726400-40
The area in yellow on the NHC map may encounter a more favorable upper level environment as it approaches the Lesser Antilles, however as stated, the atmosphere appears to be stable (lack of vertical growth.  I will be monitoring this as well during the next 5 days, just in case any significant changes occur.

Analysis this morning of various MJO and CHI200 forecast products indicates August should be a busy period, right up and into the first week of September.  The JMA CHI200 update this morning indicates the MJO (phase 2) is forecast to remain over the Atlantic basin all month.  The last graphic is the 28 day mean for the CHI 200 anomalies.  Again, blues indciate upward motion at the 200 mb level (favorable), and orange / red indicate downward motion, sinking air (unfavorable)
JMA CHI 200 FORECAST 07 – 13 AUG.
jma.1
14 – 20 AUG
jma.2
21 AUG – 03 SEP
jma.3
28 DAY MEAN
jma.4
The following is the ECMWF EPS MEAN CHI200 forecast:
ECMWF EPS CHI200 FORECAST
eps_chi200_anomaly_globe_2021080500_MEAN_120
eps_chi200_anomaly_globe_2021080500_MEAN_240
eps_chi200_anomaly_globe_2021080500_MEAN_360
FILTERED CHI200 ANOMALIES FORECAST BASED ON GFS
twc_globe_mjo_vp200
Current MJO phase space diagrams forecast indicates the MJO signal becoming stronger, with the JMA indicating a stall into phase 2 through mid Aug.
JMA PHASE SPACE DIAGRAM FORECAST
JMAN_phase_51m_full
ECMWF
ECMF_phase_51m_full
ECMWF BIAS CORRECTED
ECMF_phase_MANOM_51m_full
You may direct any questions by contacting me personally, ANYTIME, at: [email protected]

Have a blessed day!

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

Africa

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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