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(T. F. “Storm” Walsh III)
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Good day everyone!
This is my only available forecast day. I work tomorrow, have an outpatient procedure Wed., then back to work Thu-Sat.
The SPC has designated the following severe weather risk areas in the Day 1 Outlook as of the 1300Z issuance:
…THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE HIGH PLAINS…
…THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS DEEP SOUTH TEXAS…
Very isolated severe thunderstorms with hail and strong wind gusts are expected across parts of the High Plains and south Texas mainly this afternoon and evening.
Based on the analysis of the outlook, and forecast sounding data from F5 DATA using the current RAP model run, severe thunderstorms should be isolated. Based on the forecast soundings, indices support the SPC forecast. The tornado threat should be minimal, with more focus on damaging straight-line winds and hail. Looking at some of the severe parameters, the RAP model suggests the chance for severe weather may extend through west central Texas, sometime this afternoon, which is outlined in the following map.
F5 DATA RAP MODEL 3:00 P.M. CDT
Indices however, indicate the best probability for isolated supercells and possible isolated tornadoes to occur, will lie within the outlined areas in the SPC outlook maps.
Residents in the outlined SPC risk areas, should monitor NOAA Weather Radio, and local NWS statements for up to date information regarding any necessary actions.
IF A TORNADO WARNING IS ISSUED FOR YOUR AREA…SEEK SHELTER IMMEDIATELY!
The following graphics are linked to their respective sites. Mouse over and click on the graphics for up to date information.
An ongoing storm (gale) has been designated INVEST 91L and information is being disseminated through ATCF. This appears to be the area I mentioned earlier last week, which was forecast to open into a trof, and be kicked out. Obviously since my last synopsis on the area, conditions have changed. As of the 12Z ATCF BTK report, the following was available on INVEST 91L:
8:00 PM EDT Mon Apr 17
Location: 32.7°N; 64.8°W
Movement: Nearly stationary
Min pressure: 986 mb/29.12 in
Max sustained: Near 60 mph
Based on my analysis of current information, there appears to be very minimal convection on the west side of this system. This system is currently baroclinic in nature, and based on analysis of the 06Z TAFB Surface analysis map, this low is associated with a cold occlusion.
Albeit wind shear over the system is only 15 kts, and is forecast to become less favorable, then back to favorable after 48 hours, drier air surrounds the outer periphery of the system, SST’s over the area do not support sub-tropical transition, very low levels of TPW (Total Precipitable Water) are indicated, along with zero OHC (Oceanic Heat Content). The upper level wind pattern is counter-clockwise over the system, in which a low can deepen, however it becomes a very slow process, as opposed to having a clockwise flow aloft.
CIMSS 91L WIND SHEAR PATTERN
CIMSS 91L SST
CIMSS 91L TPW
CIMSS 91L DRY AIR
CIMSS UPPER LEVEL WINDS
IF this takes on sub-tropical characteristics, and becomes a sub-tropical entity, I will be very surprised.
Analysis of current and forecast steering tends to indicate this low should meander about during the next 72 to possibly 96 hours, performing a cyclonic loop, and should slowly weaken and begin to move off slowly to the ENE thereafter. Shipping interests may wish to monitor the progress of this system over the next 4-5 days.
Elsewhere, Tropical Storm formation is not expected.
Have a blessed day!
T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST /SEVERE WEATHER SPECIALIST
MEMBER WEST CENTRAL FLORIDA AMS