TROPICAL STORM FORMATION: IDA
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.
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Current Storm Total for 2015:
TOTAL STORMS: 9
INTENSE HURRICANES: 1
U.S. LANDFALLS: 2
StormW’s Seasonal Forecast:
TOTAL STORMS: 8
INTENSE HURRICANES: 1
Good day everyone!
Tropical Storm IDA has strengthened slightly overnight. As of the 5:00 a.m. advisory from the NHC, the following was available on IDA:
5:00 AM AST Mon Sep 21
Location: 19.8°N 47.3°W
Moving: NNW at 8 mph
Min pressure: 1003 mb / 29.62 in
Max sustained: 50 mph
Analysis of satellite loop imagery indicates IDA has become much better organized overnight, with a CDO feature now present, with banding features now present in the satellite signature. Careful, close analysis of various channels does indicate what is conveyed in the NHC forecast discussion, in that the LLC is still slightly displaced on the western portion of the CDO. Cloud tops had cooled to -80C earlier, and appear to be holding at approximately -60 to -70C at the moment.
Based on the current wind shear products, and the expansion of the CDO feature, it appears IDA could be on a slow strengthening trend, and mixing out the dry air located to her west. One prominent dry slot is noted on here western side, and it will remain to be seen if she can mix out any dry air intrusion. Current TPW and OHC values would tend to indicate she may stand a decent chance at accomplishing this. The most recent wind shear product from CIMSS does indicate that vertical shear has decreased to less than 20 kts, and may be on the order of only 12-15 kts. The mid level shear map indicates mid level shear to be 5 knots or less. One will even note what appears to be the beginning of an upper level anticyclone trying to establish itself over IDA, as noted in water vapor imagery, and upper level winds graphics.
Based on analysis of forecast wind shear products, wind shear should begin to increase to over 15 knots within 36 hours. Based on this premise, IDA should continue some strengthening during the next 24 hours, followed by some weakening thereafter as shear increases. This fits in exactly with the NHC forecast discussion, which I will post the link, as Stacey Stewart has written an excellent discussion.
WIND SHEAR FORECAST
http://ruc.noaa.gov/hfip/tcdiag/tcdiag.php?stm=10L.2015 (go to left column shr_mag)
200 MB STREAMLINE FORECAST
NHC FORECAST DISCUSSION
Based on my analysis of the current wind shear forecast products, shear is expected to decrease again after 72 hours, with the 200 mb streamline forecast indicating the presence of a developing upper level anticyclone. Based on this, and once again, inline with the NHC discussion, I have to concur with the intensity forecast at the moment, in that IDA could have a slim shot at becoming a minimal CATEGORY 1 Hurricane within the next 5-6 days. Of course, bear in mind, this is if all the parameters mentioned pan out. I am a little hesitant on the CAT 1 solution, as the consensus of the more accurate intensity models keep her just slightly below hurricane strength. However, Stewart is one of the better forecasters at the NHC.
IDA continues to move toward the NNW, and I expect this motion to continue, at least through today. Based on analysis of the forecast steering layers maps, steering currents are forecast to collapse, and IDA should become quasi-stationary out into the 72 hour forecast frame. Soon thereafter, IDA should resume a more northward motion, and possibly begin to re-curve. I concur with the NHC forecast track, which lies pretty much with the dynamic model consensus tracks.
I will continue to monitor IDA for any significant changes to the forecast pattern.
Elsewhere, the three major global models have been consistent, and appear to be coming together a little better on the solution of a large low pressure area developing near the Yucatan to BOC by late this weekend, into early next week. The GFS and ECMWF, look almost remarkably alike in their solutions in this mornings analysis, in that both tend to indicate this low to begin as a large, and weak low, then eventually consolidating into a smaller system, with possible subtropical development, becoming a minimal subtropical or tropical storm (1001 mb). Both of these models have almost the same track solution The CMC is weaker, and further left with its track. Please note, that intensity and track is only preliminary at the moment, until we can actually see a definite development, and what forecast conditions look like from that point in time. The forecast 200 mb streamline pattern does however indicate conditions could support subtropical development, with the development of a northern upper level outflow jet. I will be monitoring the area beginning this weekend, and will update when time allows.
Have a blessed day!
T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST /SEVERE WEATHER SPECIALIST
MEMBER WEST CENTRAL FLORIDA AMS