SEVERE THUNDERSTORM WARNING ISSUED

SKYWARN UK SEVERE WEATHER WARNING #026
ISSUED: 1500UTC FRIDAY 18TH JULY
SKYWARN UK SEVERE THUNDERSTORM WARNING NO:26 ISSUED AT 1500UTC FRIDAY 18th JULY 2014.

VALID FROM 1800UTC FRIDAY 18TH JULY 2014 TO 1200UTC SUNDAY 20TH JULY 2014

SKYWARN UK FORECASTS THE POTENTIAL FOR SEVERE WEATHER AS FOLLOWS: TORRENTIAL RAIN, FLASH FLOODING, THUNDERSTORMS WITH REGULAR C-G LIGHTNING ALSO THE POTENTIAL FOR SUPERCELL DEVELOPMENT. THIS WARNING COVERS THE MAJORITY OF THE UK BUT IN PARTICULAR THE SOUTHERN HOME COUNTIES, SOUTHEAST ENGLAND, THE MIDLANDS, EAST ANGLIA AND LINCOLNSHIRE. CIN MAY WELL INHIBIT STORM INITIATION IN THE FAR EAST OF EAST ANGLIA.

DISCUSSION:
THERE IS NOW GOOD MODEL AND PARTNER AGENCY CONFIDENCE IN THE POSSIBILITY OF SEVERE WEATHER THROUGHOUT THE PERIOD. A WARM, MOIST AND UNSTABLE AIRMASS WILL EXTEND INTO SOUTHERN COASTAL REGIONS OF ENGLAND LATE FRIDAY AFTERNOON AND EXTEND FURTHER NORTH AND EAST DURING THE EVENING FROM A TROUGH ASSOCIATED WITH THE COMPLEX LOW OVER THE UK AND NEAR CONTINENT. CAPE OF OVER 1500j/Kg WITH LI VALUES OF -2 TO -5 IS MODELLED OVER A WIDE AREA. OVERNIGHT FRIDAY AND INTO SATURDAY MORNING FURTHER ELEVATED PLUME DESTABILISATION WILL OCCUR AND IF UPDRAFTS ARE STRONG ENOUGH STORMS WILL INITIATE CLOSER TO THE SURFACE. DURING SATURDAY THIS COULD BRING A WIDESPREAD RISK OF TORRENTIAL RAIN WITH FLASH FLOODING. THERE IS ALSO A POSSIBILITY OF LARGE HAIL ANYWHERE WITHIN THE WARNING AREA. SOME OF THESE AREAS COULD WELL SEE DAMAGING WIND GUSTS DURING ANY STORMS. THERE IS ALSO POTENTIAL FOR SUPERCELL DEVELOPMENT GIVEN THE DIRECTIONAL SHEAR AND CAPE VALUES . THIS IS AN EXTREMELY VOLATILE SITUATION AND THIS WARNING MAY BE UPDATED TO INCLUDE OTHER AREAS. PLEASE MONITOR ALL WEATHER AND TRAVEL INFORMATION AS NECESSARY AS THERE IS A SIGNIFICANT RISK OF DISRUPTION.

SPOTTER ACTIVATION IS REQUESTED AND SPOTTERS ARE REQUESTED TO REPORT ALL FACTORS EXCEEDING ACTIVATION CRITERIA.