TROPICAL DISTURBANCE INVEST 93L FORECAST SYNOPSIS…ISSUED 11:30 A.M. EDT…OCT 21, 2014…WEST CENTRAL FLORIDA HURRICANE AND SEVERE WEATHER FORECAST CENTER

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Good day everyone!

I am still monitoring INVEST 93L in the BOC (Bay Of Campeche) this morning.  As of the 12Z ATCF Guidance report, the following was available on the disturbance:

LOCATION: 19.5N…94.0W
MOVEMENT: E DRIFT
MAX WIND: 35 mph
PRESSURE: 1005 mb / 29.68 in

Over the past 6 hours (from 06Z – 12Z), the estimated pressure has dropped 1 mb, and maximum sustained winds have increased to 35 mph.  The NHC has designated a MEDIUM (50%) probability of INVEST 93L becoming a tropical cyclone during the ext 5 days.

NHC GRAPHICAL TROPICAL WEATHER OUTLOOK

Based on proximity to land, and current wind shear charts, I am reluctant to share the NHC enthusiasm at the moment, albeit it is possible.  Analysis of current vorticity maps tend to indicate this is a shallow system at the moment, and the current mid level wind shear product indicates mid level shear over and close to the center is only 5 kts or less, even though deep layer shear is out of the west on the order of around 30 kts.  So it may be possible we could see some development up to the mid levels of the atmosphere (700 – 500 mb).  Anything above this level will begin to become sheared.  Analysis of current satellite loop imagery indicates albeit the system has become a little better”defined”, shower and thunderstorm activity remain disorganized.

INVEST 93L FLOATER SATELLITE LOOP IMAGES

GOMEX SATELLITE LOOP IMAGERY

Analysis of the current wind shear maps from both the GFS and CMC Global Models indicate upper level winds should remain only slightly conducive, in being the flow aloft is diffluent, which should aid in some sort of ventilation for the system, and is noted in the upper level wind profile in the current CIMSS product, indicating an outflow jet to the north of 93L, and around to the east and southern quadrant of the system.  In about 48 hours, both models indicate upper level winds to become more conducive for some slow development, with an upper level anticyclone forecast to take shape over the Yucatan peninsula, then entering the Yucatan channel.  Based on this premise, I am not really looking for anything different in rate of development on this system, until if and when it emerges into the Yucatan channel.  Right now, based on this analysis, and uncertainty of where exactly the COC may wind up, I have to concur with the majority of the intensity forecast modeling, in keeping this below tropical storm strength.

CIMSS WIND SHEAR

CIMSS UPPER LEVEL WIND PROFILE

12Z INTENSITY FORECAST MODELS
93L intensity
Based on the current steering flow, the current motion of this system really doesn’t make sense.  There is blocking to the north, however based on the weakness in the ridge to the NE, a slow motion more toward the NE should be prevalent, although it may be meandering now, as steering is weak over the area.

CURRENT STEERING

Based on my analysis of the current steering layers forecast maps, I have to agree with the ATCF 12Z Dynamic Track Guidance and the consensus models TVCN / TV15 / TVCC.

Based on the performance of these dynamic models this season, this track is what will most likely occur.  However, the time frame on guidance modeling is out to 96 – 120 hours.

12Z ATCF DYNAMIC MODEL TRACK GUIDANCE
93L DYNAMIC

NOW, here is where a monkey wrench comes into the forecast (No, it couldn’t be a simple system).  Global models indicate if and when this makes it to the Gulf of Honduras (do you remember me mentioning about the front this system is supposed to merge with?) that this system becomes elongated, which is not unheard of, especially in October with a system of this size and nature, with 2 low centers then being evident which is noted in the Global models, and is in the first graphic of each model.  IF this pans out, then we have what appears to be something of a trof split.  The weaker low then gets carried NE by the front.  HOWEVER, models suggest the southern most, stronger center, breaks off, and remains in the W. Caribbean.  2 of the models extending out mid range, the GFS and CMC develop this low, and move it northward.  The GFS sends it across W. Cuba, and then toward S. Florida, but weakening it after crossing Cuba.  The ECMWF does indicate a very small low hanging back, but is much weaker and steers it toward Honduras. The NAVGEM also supports leaving a low behind in the Caribbean.

GFS
GFS1

GFS2
ECMWF
ECMWF1
CMC
CMC1

CMC2
NAVGEM
NAVGEM1

NAVGEM2

Now, I’d appreciate not being bombarded by questions as to whether or not is it going to hit Florida, or the west coast of Florida, or the Panhandle of Florida, or New Orleans, etc., because right now, it’s up in the air as to whether or not this actually occurs…being over 6 days out in the forecast period, if this disturbance even survives interaction with the Yucatan peninsula.

I will continue to monitor the situation closely, but will not have another update until tomorrow.

Elsewhere, a surface low is forecast to swing out off the NEUS coast near Maryland, with a coastal development taking shape in about 18-24 hours.  I will try to incorporate this into the forecast tomorrow.

GFS
GFS3

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
OFFICIAL SKYWARN SPOTTER (ADVANCED)

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