TROPICAL DISTURBANCE INVEST 95L FORECAST SYNOPSIS…ISSUED JUL. 16, 2017…4:05 P.M. EDT

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(T. F. “Storm” Walsh III)

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STORM W’s SEASONAL HURRICANE FORECAST
TOTAL STORMS: 14-16
HURRICANES:       6-8
MAJ. HURRICANES: 3-4

CURRENT TOTALS
STORMS: 3
HURRICANES: 0
MAJ. HURRICANES: 0

U.S. LANDFALLS: 1

Good day all!

A Tropical Wave located approximately 1000 miles ESE of the Windward Islands has been designated INVEST 95L by the ATCF and NHC.  The NHC has designated a MEDIUM (40%) probability of cyclone development over the next 5 days. 

NHC 5 DAY GRAPHICAL TWO

As of the 1800Z ATCF BTK product, the following was available on INVEST 95L:

2:00 PM AST Sun Jul 16
LOCATION: 10.5N…45.9W
MOVEMENT: W 16 mph

PRESSURE: 1011 mb / 29.85 in
MAX SUSTAINED WIND: 25 mph

INVEST 95L FLOATER SATELLITE LOOP

CATL WATER VAPOR LOOP (CLICK IMAGE)

Based on my analysis of the latest available current wind shear product from CIMSS, INVEST 95L is in an area where wind shear values are relatively weak.  Albeit the pattern is currently lacking an upper level anti-cyclone, conditions are marginal to somewhat favorable, as an upper level low positioned NE of the wave, is aiding in evacuating air in the upper levels, as noted by a northern outflow channel or “jet” north of the wave.  The resultant upper level flow is causing limited divergence aloft.

INVEST 95L WIND SHEAR MAP

INVEST 95L UPPER LEVEL WIND PATTERN FROM CIMSS

Based on the current wind shear forecast from the GFS, upper level winds may become a little more conducive during the next 24 hours or so, developing somewhat of a small, upper level anticyclone over the wave as it approaches the Windward Islands.  Based on this, there may be a small window of opportunity for some slow development over the next 48 hours, as the upper level winds remain somewhat favorable.  There is currently a good TPW signature associated with the disturbance, and although drier air is seen north of the system, high TPW values and with the disturbance approaching an area of more OHC (Ocean Heat Content), it may be able to fight off most of the drier air. 

INVEST 95L TPW MAP

INVEST 95L OHC MAP FROM CIMSS

So, this system does have some factors in its favor for at least the next 48 hours.  At around 72 hours in the forecast period from 12Z, upper level winds are forecast to become unfavorable for any further chance of development, as it stands right now, based on the premise of increasing wind shear.

GFS WIND SHEAR FORECAST

The GFS and ECMWF do not develop this wave, with the (you guessed it) CMC indicating a tropical storm as it enters the southern Caribbean.  Model Intensity guidance (SHIP and DSHP) bring INVEST 95L to CAT 1 hurricane status in 72 hours, and the LGEM indicates a weak tropical storm.  Based on my analysis, I am more inline with the LGEM, IF forecast data is accurate.  Personally (unless conditions change for a more favorable outlook) I feel we may see only a tropical depression to minimal tropical storm at best, (based on current forecast conditions).  But, we’ll see how future conditions pan out.  Both track and intensity guidance at this time, should be considered preliminary at best, until models have a better defined system to work with.

18Z ATCF INTENSITY GUIDANCE

INVEST 95L is currently south of the subtropical ridge which is moderately strong at the moment, and is in a strong westerly flow, hence current movement.  I expect this motion to continue during the next 36 hours, with a possibility of the INVEST gaining somewhat of a small northward component due to a current weakness in the ridge located north of Hispaniola/Cuba, which is forecast to remain for the next 36 hours.  Soon thereafter, the ridge axis shifts more toward the west, and the pattern takes on a more negative NAO type pattern, with a ridge building in north of Puerto Rico, and another center more toward the Eastern Atlantic.  The resultant flow SHOULD continue to send the system westward, and is most likely what current model guidance is picking up on.  As I stated, I believe the wave could lift slightly more northward over the next 36 hours, but then resume a more westerly component.

INVEST 95L CURRENT STEERING LAYER (CLICK FOR LARGER IMAGE)

18Z DYNAMIC MODEL TRACK GUIDANCE (CLICK FOR LARGER IMAGE)

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

Have a blessed day!
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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6 Responses to TROPICAL DISTURBANCE INVEST 95L FORECAST SYNOPSIS…ISSUED JUL. 16, 2017…4:05 P.M. EDT

  1. dellamom says:

    Thank you, Storm. And just a reminder that we in coastal areas don’t need a TD, TS, or H for trouble; even a relatively minor system sitting off the coast and moving slowly can have us sitting on roofs and traveling by boat. I’m glad we have you to get information to us in understandable terms.

  2. greg goodman says:

    mr storm thankyou for the update.Mr storm do you think this is a trend for systems developing east of the islands?Seems like we have had quiet more activity this year than this same time last year.

    • Well, I think it can be attributed to the fact we are in ENSO Modoki conditions. Earlier this month and in June, we were mainly in a neutral to negative NAO as well (weaker sub-tropical ridge), so things were able to organize easier. As far as Jul, activity really hasn’t been that great. No named systems as of yet, which was the case last season.

  3. javier says:

    so going same history as other td in area?

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