TROPICAL STORM GRACE FORECAST SYNOPSIS…ISSUED SEP. 06, 2015…11:10 A.M. EDT

TROPICAL STORM FORMATION: GRACE

ALL forecasts contained on this site,  are based on my analysis and knowledge of various forecast tools, including information contained in NHC products, and are not copies from any other entity.

*NOTE: In the TROPICAL STORM FORMATION line above, probabilities are for during the next 5 day period.  My personal probability will be listed as either NONE, MONITORING or PROBABLE.  This does not necessarily mean something will develop, but that certain forecast conditions are likely to be present, favoring development.  Once NHC products become available, then the appropriate probability and percentage will be used.

Please refer to the link for the Storm Prediction Center in the box at the top of the page, just below the Hurricane Hunter graphics.

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Current Storm Total for 2015:

TOTAL STORMS: 7
HURRICANES: 2
INTENSE HURRICANES: 1
U.S. LANDFALLS: 2

StormW’s Seasonal Forecast:

TOTAL STORMS:             8
HURRICANES:                   3
INTENSE HURRICANES: 1

Good day everyone!

Tropical Storm GRACE continues to move toward the west, with estimated sustained winds of 45 mph.  As of the 5:00 a.m. advisory, the following was available on Tropical Storm GRACE:

11:00 AM AST Sun Sep 6
Location: 12.9°N 29.9°W
Moving: W at 14 mph
Min pressure: 1004 mb/29.65 in
Max sustained: 45 mph

HURREVAC NHC TRACK MAPS
HURREVAC.GRACE

HURREVAC.GRACE72

Based on satellite loop images, and current steering layer mean, GRACE is moving toward the west, on the southern periphery of the subtropical ridge.  Based on my analysis of the current steering layers forecast maps, I concur with the NHC forecast in that GRACE should continue on the west, to just north of west track during the next 72-96 hours.  Thereafter, a weakness/break in the subtropical ridge is forecast near 65W, which would allow GRACE to ensue a more WNW track.  However, past day 5, forecast steering suggests the ridge to begin to fill and expand more toward the west, at which time there could be a bend back toward the left.  This will remain to be seen, as this is stepping beyond the bounds of reliable steering accuracy, however would coincide with a weaker system moving more toward the west, and is reflected in the 12Z Dynamic Model guidance TVCN track.

GRACE FLOATER SATELLITE LOOP IMAGERY
avn0grace-lalo

METEOSAT 4 CIRA GRACE FLOATER LOOP IMAGERY
tropical_met_4km_ir4_floater

tropical_met_4km_visir2_floater

CURRENT LAYER MEAN STEERING
wg8dlm2

ATCF 12Z DYNAMIC MODEL GUIDANCE
GRACE 12Z DYNAMIC GUIDANCE
GRACE continues to have convection wax and wane near her center, which would tend to lend credence to still some dry air ingestion.  Close up water vapor loop imagery tends to verify this, as well as the presence of a stratocumlus cloud deck to her north, indicating stable dry air.

GRACE FLOATER WATER VAPOR LOOP
wv0grace-lalo

Satellite loop imagery tends to show a fairly tight core, and some slight banding features becoming a little more prominent over the last few hours.

The most recent available shear map indicates GRACE to be on the western periphery of an upper level anticyclone.  The current flow is still providing some outflow aloft, with the strongest outflow channel being located on the southern portion of the storm.

CIMSS GRACE SHEAR MAP
tccaptureshear

The current wind shear forecast continues to call for upper level winds to improve, with the upper level anticyclone developing over GRACE, and maintaining itself for approximately the next 48 – 60 hours.  Zonal shear, based on the forecast, should remain low up until that point.  Thereafter, should GRACE remain on track, SWLY shear is forecast to begin to develop.  This should begin to weaken GRACE.  The SWLY shear is forecast to remain in place well past the forecast period, which would indicate a decent probability of GRACE’s demise later in the period.  Based on this shear forecast, I concur with the current NHC intensity forecast.  I believe the slow strengthening will be attributed more to drier air, vice upper level winds.

GFS ZONAL SHEAR MAP
850200ushear9
NHC INTENSITY FORECAST

INIT 06/1500Z 12.9N 29.9W 40 KT 45 MPH
12H 07/0000Z 13.0N 32.0W 45 KT 50 MPH
24H 07/1200Z 13.3N 34.7W 50 KT 60 MPH
36H 08/0000Z 13.6N 37.4W 55 KT 65 MPH
48H 08/1200Z 13.8N 40.1W 55 KT 65 MPH
72H 09/1200Z 14.3N 45.3W 50 KT 60 MPH
96H 10/1200Z 15.0N 50.5W 40 KT 45 MPH
120H 11/1200Z 15.5N 55.5W 35 KT 40 MPH

I will continue to monitor GRACE for any significant changes.

Elsewhere, I will be monitoring a tropical wave exiting the African coast, south of where GRACE entered the Atlantic.  This feature currently has an  upper level anticyclone over it, and upper level winds are forecast to remain somewhat favorable for the next 3 days.  We’ll have to see what happens as this hits the ocean, as there doesn’t appear to be as much convection or moisture with it.

EUMETSAT SATELLITE LOOP IMAGERY
EUMETSAT_MSG_IR108Color-westernAfrica

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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2 Responses to TROPICAL STORM GRACE FORECAST SYNOPSIS…ISSUED SEP. 06, 2015…11:10 A.M. EDT

  1. Elliot Lisak says:

    Good Afternoon Storm,

    Who said it was going to be a quiet, booring and uneventful season. I think by the time we get done we will definitely beat your Seasonal Forecast. How long will the high stay in place in the Atlantic and how powerful will the High. Secondly will the shear at its current levels stay around for the balance of this season …..

    Thank you for taking the time to explain todays forecast.

    Best Regards for a restful and peaceful Labor Day Weekend,

    elliot

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