Good day everyone!
Looks like an active week for severe weather, especially this upcoming weekend, which will be discussed later in this synopsis.
The SPC (Storm Prediction Center) has issued a SLIGHT risk of Severe Thunderstorms for portions of NWRN WY…SERN ID…SWRN MT…
The main threat for today should be damaging straight line winds, with the secondary threat in the form of some hail. Having looked at some parameters this morning, I am not expecting anything that significant…however residents in the risk area should monitor this situation for isolated damaging hail.
As we get into the day 2 outlook, the severe threat becomes a little more robust in coverage and likelihood of stronger storms and isolated tornadoes, with a good probability of significant severe weather within a moderate sized area of the risk outline .
The SPC has issued a SLIGHT risk of Severe Thunderstorms ACROSS THE CENTRAL AND SOUTHERN PLAINS…
At this time, based on analysis of early morning information provided by the GFS and NAM – WRF through F5 DATA Severe Weather Software, the most likely probability for isolated tornadic activity may occur within the outlined area, where SWEAT values could attain 400+…please refer to the severe weather indices chart regarding SWEAT values.
SEVERE WEATHER INDICES LINK
I will try to have an update on this in the morning.
Based on information contained in the SPC Day 4 – 8 Severe Weather Outlook, a SIGNIFICANT SEVERE WEATHER EVENT IS FORECAST FOR SATURDAY / SUNDAY.
SPC DAY 5 AND 6 TEXT DISCUSSION
DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0345 AM CDT TUE APR 22 2014
VALID 251200Z – 301200Z …
DISCUSSION… …SIGNIFICANT MULTI-DAY SEVERE EVENT EXPECTED ACROSS THE SOUTH CENTRAL U.S. SATURDAY AND SUNDAY…STRONG TORNADOES ARE POSSIBLE…
22/00Z ECMWF IS EXHIBITING REASONABLE RUN-TO-RUN CONSISTENCY OVER THE LAST FEW DAYS WITH THE GFS NOW TRENDING TOWARD ECMWF SOLUTIONS. THIS FORECAST IS HEAVILY WEIGHTED TOWARD THE ECMWF.
EARLIER CONCERNS REGARDING A POLAR FRONT UNDERCUTTING STRONG SWLY FLOW ALOFT OVER THE SRN PLAINS ARE LESSENING. WHILE UPPER BLOCK OVER CNTRL CANADA WILL ULTIMATELY FORCE A DOMINANT SFC ANTICYCLONE INTO THE MIDDLE OF THE CONUS…IT APPEARS THE LEADING EDGE OF THIS AIR MASS SHOULD STRUGGLE TO ADVANCE MUCH SOUTH OF I-70 OVER KS/MO THIS WEEKEND.
STRONG MID-LEVEL SPEED MAX IS FORECAST TO DIG SEWD INTO THE LOWER CO RIVER VALLEY SATURDAY WITH UPPER DIFFLUENCE EXPECTED ACROSS THE PLAINS AS FAR SOUTH AS WEST TX AT 27/00Z. THIS EVOLUTION WILL ALLOW SUBSTANTIAL MOISTURE TO ADVANCE POLEWARD ACROSS THE SRN PLAINS WHERE PW VALUES SHOULD EASILY APPROACH 1.25 INCHES AS SFC DEW POINTS CLIMB THROUGH THE MID-UPPER 60S ACROSS A BROAD WARM SECTOR. LATEST THINKING IS MODERATE-EXTREME INSTABILITY SHOULD DEVELOP ALONG ERN PLUME OF STEEP LAPSE RATES FROM WCNTRL TX…NWD INTO SCNTRL KS SATURDAY WHERE MUCAPE COULD APPROACH 4000 J/KG. IF THERMODYNAMIC ENVIRONMENT EVOLVES AS LATEST GUIDANCE SUGGESTS THEN POTENTIALLY SIGNIFICANT SUPERCELL DEVELOPMENT WITH VERY LARGE HAIL AND TORNADOES CAN BE EXPECTED. CONVECTION SHOULD INITIATE ALONG DRYLINE FROM SWRN TX…NWD INTO WRN KS SATURDAY THEN REDEVELOP AGAIN SUNDAY FROM SERN KS…SWD INTO CNTRL TX AS MID-LEVEL SPEED MAX EJECTS INTO THE SRN PLAINS. SEVERE TSTMS SHOULD SPREAD INTO THE MS VALLEY BY EARLY MONDAY. ORGANIZED SEVERE MAY CONTINUE INTO THE DAY7 PERIOD BUT SUBSTANTIAL CONVECTION DURING THE DAY5-6 TIME FRAME COULD POTENTIALLY DISRUPT THERMODYNAMIC ENVIRONMENT…THUS CONFIDENCE IS NOT AS HIGH…
The following parameters could change, as the forecast is out to 120 hours in the period…but as it stands at the moment, should the current forecast severe weather indices materialize, this event has the potential to evolve into a PDS (Particularly Dangerous Situation), and could even become DEADLY. Just to give some current forecast values, I have chosen just three at this time, and these values could approach, or attain the level posted, which are indicative of very significant severe weather:
SBCAPE: 2000 – 4000 j/kg
MLCAPE: 1500 – 3000 j/kg
SWEAT INDEX: 450 – 525
Once again, being 120 hours out in the period, these values could change…IF they pan out…severe weather could become every significant, with strong, long track tornadoes.
I will continue to monitor this possible event, and will try to update as much as possible on this situation.
The following graphics are linked so you may click on them for up to date information…PLEASE USE THEM!
Have a blessed day!
T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST / SEVERE WEATHER SPECIALIST
MEMBER WEST CENTRAL FLORIDA AMS
OFFICIAL SKYWARN SPOTTER (ADVANCED)