PRE-SEASON TROPICAL WEATHER DISCUSSION FORECAST SYNOPSIS…ISSUED 5:05 P.M. EDT…MAY 22, 2016

SEVERE WEATHER RISK: ENHANCED
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)

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Good day everyone!

The SPC has designated an ENHANCED risk for Severe Thunderstorms in the day 1 convective outlook.

SPC DAY 1 CONVECTIVE OUTLOOK
day1otlk_1630

TROPICAL WEATHER OUTLOOK DISCUSSION

First,  satellite imagery indicates another  MCS in the GOMEX this afternoon.  This area does not pose any threat for development.

SSEC GEOSTATIONARY SATELLITE LOOP
latest_east_ir4_conus

NOAA EASTERN U.S. SATELLITE LOOP
jsl-l

RAMSDIS GOES EAST U.S. SATELLITE LOOP
geir404

The 12Z surface analysis map from NHC TAFB indicated 2 tropical waves moving toward the west.  The wave located near 44W is moving at around 15 kts.  A second wave, onshore over the extreme north coast of South America is moving at around 10 knots.  Both of these waves do not display and discernible satellite signature.

12Z NHC TAFB SURFACE ANALYSIS (CLICK FOR LARGER IMAGE)
USA_12Z

Analysis of the global models today indicate the weak coastal low, which has been being shown over the past 5 days or so, is coming to fruition.  Satellite imagery and the TAFB  surface analysis indicate a 1008 mb low is just along, or now sightly off the SE NC coastline.  The primary low associated with this system is moving toward Nova Scotia, and is east of Cape Cod.  The satellite overlay, along with the GFS and ECMWF global models indicate this as what I refer to sometimes as a double barrel low, to become split, with the low off the NC coast becoming the dominant feature.  Based on analysis of the 1000-500 mb thickness charts, this low is forecast to phase with a 500 mb cutoff low, and should remain baroclinic in nature.  At the moment of the most current model runs, winds will be at their worst, east of the center of the low, and are forecast at the moment to approximately 25 knots tops.  I do not foresee any problems right now inland with this, however the possibility of some heavier surf and winds along coastal areas north of the center does exist.

GFS
gfs_mslp_uv10m_conus_10

CMC GGEM
cmc_mslp_uv10m_conus_9

ECMWF
ecm_mslp_uv850_conus_3

Over the past few days, the global models have been hinting at the possibility of a “situational development” anywhere from the extreme western Caribbean, to the north central Bahamas.

Analysis of the global models 12Z runs indicates the models are still trying to “sniff” something out in the day 6-10 time frame in the forecast period..  The only model not indicating development of a low at them moment, is the ECMWF and CMC GGEM.

The GFS develops a low, east of Florida at about day 6 (147 hours), moving it slowly northward off the east coast, while it strengthens slowly.  This low gradually moves inland over Georgia by the 31st of May.  The 1000-500 mb thickness indicates at the moment, that IF this occurs, it doesn’t begin a transition to warm core until it comes inland.  Right now, pressures (1002 mb…29.59 in.) and wind speed indicate this would only be a tropical depression, IF it develops.  The GGEM indicates only a wave in the isobars, however it comes up with a low in the south central Caribbean Sea, north of Panama in 10 days.  Both FIM models are in between the GGEM and GFS, indicating a weak system a little further east of FL. at around the 8 day time mark.

GFS 147, 187, AND 228 HOUR FORECAST MAPS
GFS.147gfs.187

gfs.228
FIM 8
FIM8.wind_10m_f204

FIM 9
FIM.9wind_10m_f204

CMC GGEM 240 HOURS
CMC.240

ECMWF 240 HOURS
ECMWF.240
So, we have the dilemma of “which model is correct”.  After some thought on this, I cannot totally rule out the GFS at this time, as we don’t know how it’s going to perform since the upgrade earlier in the month.  I will say one thing, it did keep up with the ECMWF in forecasting the current low “pattern” off the east coast.  Second, I cannot totally rule it out, as we do see some lowering of pressures over the Cuba area in about day 6-7.

Based on the other models solutions (the slower solution), the GFS “COULD” be an outlier, as the FIM indicate slow development at 8-9 days out, with a low going out to sea.

The CMC GGEM then develops a low over the south central Caribbean.

This could possible be the better of the scenarios, as the ECMWF and ESRL PSD 500 mb anomalies indicate a significant lowering of pressures ate 216-240 hours out in the forecast period, and have been consistent run to run over the past 6 days.  Regardless of which model is correct, I will be monitoring the area where the significant of the pressure drop is indicated.  The GFS does indicate an improvement in the upper level wind pattern, with a weak upper level anticyclone becoming evident off the U.S. east coast at 180 hours out in the forecast period from 12Z today.

ECMWF 500 MB ANOMALY
ecm_z500_anom_conus_11ESRL PSD 500 MB MEAN NORM ANOMALY
z500nanom_f216_usbg

GFS 200 MB STREAMLINE PATTERN 180 HOURS
gfs.200.streamline
Elsewhere, Tropical Storm formation is not expected during the next 7-10 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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4 Responses to PRE-SEASON TROPICAL WEATHER DISCUSSION FORECAST SYNOPSIS…ISSUED 5:05 P.M. EDT…MAY 22, 2016

  1. At this time of the year, with the “Tropical Season” only 10 day away from its “official” start, I find it is comforting to know that our buddy, “Storm”, is on our side and is going to help us understand what may be ahead in the coming weather forecasts.

    With that in mind, I see that it has been about six months since I made a minor, monetary, contribution to keep those forecasts coming. Sorry, “Storm”! I too am on
    Social Security and savings, and find it necessary to budget carefully. With that in mind, I move my mouse to the upper-right part of your screen – and “click”! It was easy and, yes I know – it’s not much, but, I feel, satisfying (At least to me!).

    Thanks for the week-end updates! (Don’t you hate it when those “Lows” start dancing around?

    The Beachbums of Port Aransas.

  2. grannyMS says:

    Thank you, Storm!

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