TROPICAL DEPRESSION EMILY / TROPICAL WEATHER OUTLOOK FORECAST SYNOPSIS…ISSUED AUG. 01, 2017…1:15 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: 5
HURRICANES: 0
MAJ. HURRICANES: 0

U.S. LANDFALLS: 2

UPDATE…2:00 P.M. EDT:

The NHC has added the CATL tropical wave to the GTWO:

NHC 5 DAY GRAPHICAL TROPICAL WEATHER OUTLOOK

Good day all!

Ok.  Wasn’t able to update yesterday, as I had to work. A lot to go over, so I am going to try to not make this very graphics intense.

The area of low pressure (INVEST 98L) that had formed along the front in the GOMEX late on JUL 30, was designated Tropical Storm EMILY early yesterday morning.  I know some of my subscribers were concerned for my safety, and I appreciate that!  However, EMILY came ashore late yesterday morning over Anna Maria Island, which is south of my area.  The map shows Tarpon Springs (where I forecast from), and Anna Maria Island.

WEST CENTRAL FLORIDA MAP

Yesterday evening, I had posted on Facebook, as to WHY did the NHC name this as a Tropical Storm.  My reasoning was, analysis of various surface analysis maps seemed to indicate this low was still involved with the front, and riding along it.  So, this made me question as to why it was named, being the criteria for a tropical or sub-tropical system, by definition, is a NON FRONTAL feature: Subtropical Cyclone: A non-frontal low-pressure system that has characteristics of both tropical and extratropical cyclones. Like tropical cyclones, they are non-frontal, synoptic-scale cyclones that originate over tropical or subtropical waters, and have a closed surface wind circulation about a well-defined center.

SURFACE ANALYSIS MAPS FROM YESTERDAY

I took the time to perform further research this morning, prior to analysis.  Based on this research, the NHC was correct in the naming of EMILY.  Information accessed revealed that the low was “warm core”. You’ll note in the graphic, warmer temperatures where the “center” in located

AMSU DATA (Red line indicates approx. center of the storm)

Archived satellite imagery did indicate, that EMILY was most likely centered just north of the frontal boundary as she approached the FL. west central coastline.  First image is when development began (white arrows indicate the front).  Second image indicates EMILY near landfall (red box).

Having appeared to be within the front however, it was my thought, along with the 20-25 kts of NW shear, that is was being maintained by baroclinic processes.  So, in my last forecast, it appeared that tropical development may not occur prior to landfall, or even organized development.  If you remember, the NHC also had a low probability of 30% assigned to it for cyclone development over the 5 day period.  Once again, this reiterates what you hear me preach, that conditions can change very quickly.  So, my take on what we wound up with, is a quick developing tropical system.  The wind shear mentioned, is most likely why EMILY did not get any stronger than what she did prior to landfall.

With that said, as of the 11:00 a.m. EDT advisory from the NHC, the following was available on Tropical Depression EMILY:

11:00 AM EDT Tue Aug 1
Location: 29.3°N 78.9°W
Moving: NE at 14 mph
Min pressure: 1011 mb / 29.85 in
Max sustained: 30 mph

HURREVAC NHC TRACKING MAP

Satellite imagery indicates the center of EMILY is exposed to the SE of any convection.  It is noted however that convection appears to be flaring up near the center.  Based on the current wind shear forecast, I am not expecting EMILY to re-attain TS status, however vertical shear is expected to remain in the 10-15 knot range, and if convection continues to build and persist during the next 12 hours, there could be some slight strengthening.  This is reflected in the NHC intensity forecast.

EMILY SATELLITE IMAGERY (CLICK FOR LOOP)

NHC INTENSITY FORECAST
INIT 01/1500Z 29.3N 78.9W 25 KT 30 MPH

12H 02/0000Z 30.4N 77.5W 30 KT 35 MPH
24H 02/1200Z 32.1N 75.1W 30 KT 35 MPH
36H 03/0000Z 33.9N 72.0W 30 KT 35 MPH…POST-TROP/EXTRATROP
48H 03/1200Z 35.3N 68.8W 30 KT 35 MPH…POST-TROP/EXTRATROP
72H 04/1200Z 37.6N 62.2W 30 KT 35 MPH…POST-TROP/EXTRATROP
96H 05/1200Z 39.0N 55.5W 30 KT 35 MPH…POST-TROP/EXTRATROP
120H 06/1200Z…DISSIPATED

Based on my analysis of current and forecast steering maps, and zonal wind shear forecast, I concur with the NHC forecast track which is within the dynamic guidance and I concur intensity scheme.

EMILY DYNAMIC GUIDANCE

I will continue to monitor EMILY for any significant changes during the next 48 hours.

Elsewhere, I am still following the tropical wave located in the CATL today.

CATL SATELLITE LOOP

Based on analysis of forecast zonal wind shear, there could be a slight probability for this wave to become slightly better organized during the next 48-72 hours, before it begins to hit some westerly wind shear as it moves close to the Caribbean Sea.  For some reason, wind shear over the Caribbean has been averaging above climatology so far this season.  I had not really expected this, in a non El Nino season.  Some drier air is noted to the NE of this wave, however water vapor imagery indicates there could be enough moisture to help fight the dry air.  The wave does have an excellent TPW signature.  Although this wave is not mentioned in the NHC Tropical Weather Outlook, I will continue to monitor this wave for any significant changes in the pattern.

GFS ZONAL SHEAR FORECAST

CARIBBEAN WIND SHEAR GRAPH

ATLANTIC MID AND UPPER LEVEL WATER VAPOR

Ok.  I know folks are still concerned in that the “active season” theory may bust.  I could be wrong, but I’m not willing to bet on a bust, at least not yet.  We are beginning to move into the period where “climatology” begins to ramp up.  Now, some of the parameters I’ve (we’ve…for my various weather enthusiasts) monitoring, as far as favored conditions for an increase in tropical activity in the Atlantic, have been waxing and waning, however for the most part, still indicate favorable conditions ahead.  Depending on which MJO (Madden Julian Oscillation) forecast you want to go with, as there is slight discrepancies in the modeling, along with the same for the current CCKW (Convectively Coupled Kelvin Wave) forecast, they pretty much show some improving conditions around the second week of this month.  IF the current 200 mb Vertical Velocity Potential Anomalies forecast is correct, and the above MJO predictions pan out, I would not expect a decent upturn in activity until probably within the Aug. 10 -15 time period.  As I stated in one of my previous forecasts, I read an article from the AMETSOC regarding the increase in cyclogenesis potential as it relates to the MJO.  If memory serves me correctly, there is a 5 day lag time from when the MJO enters a region, until enhanced convective activity occurs.  Long story short, I just cannot buy not seeing an increase in activity, given the SST anomaly pattern we are in, the NAO forecast to remain negative over the next 2 weeks, and the recent NINO 3.4 update showing continued neutral conditions.  In fact, based on the trend for the NINO 3.4 region, I did some analysis with the Oceanic Nino Index, which brought another analog year into play, the closest being 2001…which produced 15 named storms, 9 hurricanes, and 4 major hurricanes.

CURRENT SST ANOMALIES

NAO FORECAST

NINO 3.4 FORECAST (CLICK IMAGE)

MJO FORECASTS FROM VARIOUS MODELING

CCKW FORECAST (VARIOUS)

200 MB VERTICAL VELOCITY POTENTIAL ANOMALIES CURRENT AND FORECAST

You will notice, vertical shear has been below climatology over the MDR.  However, vertical instability has been well below climatology.  This may be changing, based on the current trend.

TROPICAL ATLANTIC WIND SHEAR TIMELINE

TROPICAL ATLANTIC VERTICAL INSTABILITY

Even though Global Models do not really indicate any development, they do indicate a lowering of MSLP pressure anomalies over VARIOUS locations the Atlantic during the next 10 days.  CMC shows a low developing off Africa.

ECMWF

GFS


CMC

Elsewhere…I am not expecting tropical storm development during the next 5-7days.

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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4 Responses to TROPICAL DEPRESSION EMILY / TROPICAL WEATHER OUTLOOK FORECAST SYNOPSIS…ISSUED AUG. 01, 2017…1:15 P.M. EDT

  1. Greg Goodman says:

    Mr Storm I have a question.I think I remember you saying the steering pattern changes every 2 weeks. What does that mean for the united states as for as landfalls as for as tropical system’s

    • I haven’t really looked much. I’ll have a look tomorrow out to 6 days and see what the pattern looks like. Generally, when the NAO is not too negative, there’s a tendency for storms to travel more to the west.

  2. Mac says:

    Thanks Storm. Based on the news reporting, it looks as though the Tampa to Fort Meyers area got most of the heavy weather. Glad it mostly missed you.

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