Download FFECTIVE THIS MONDAY NIGHT FROM 630 PM UNTIL MIDNIGHT

FFECTIVE THIS MONDAY NIGHT FROM 630 PM UNTIL MIDNIGHT MDT.
HAIL TO 1.5 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.
THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 5 STATUTE MILES EAST AND WEST OF A LINE FROM 65 MILES NORTH OF GOODLAND KANSAS
TO 40 MILES SOUTH OF GOODLAND KANSAS. FOR A
COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE
UPDATE (WOUS64 KWNS WOU1).
REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH AREA. PERSONS IN
THESE AREAS SHOULD BE ON THE LOOKOUT FOR TREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE WARNINGS. SEVERE
THUNDERSTORMS CAN AND OCCASIONALLY DO PRODUCE TORNADOES.
OTHER WATCH INFORMATION...CONTINUE...WW 540...
DISCUSSION...MCS WITH A HISTORY OF DAMAGING WINDS CONTINUES TO ORGANIZE THIS EVENING OVER THE HIGH PLAINS OF NERN CO WITHIN A STEEP LAPSE RATE
ENVIRONMENT WITH MLCAPE OF 1000-2000 J/KG. GIVEN THE 40 KT MIDLEVEL FLOW OBSERVED BY 00Z DENVER SOUNDING AND ELY LOW-LEVEL WINDS...KINEMATIC
ENVIRONMENT WILL BE SUPPORTIVE OF FORWARD PROPAGATION OF MCS WITH THE THREAT FOR DAMAGING WINDS SPREADING EWD ACROSS THE WATCH AREA.
AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND A LOFT TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60 KNOTS. A FEW
CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM MOTION VECTOR 27030.
This storm currently forming over the Kansas region has the potential to produce most of the
severe storms we are able to see in the U.S. this time of the year. Going over a description of
how each storm is formed it is interesting to point out that one or more of the hazardous storms
features or elements is required to form another part of the storm. They build off each other and
as the elements presents themselves more fully the storm will typically become more severe in
nature.
The first element mentioned in this storm is the 1.5” hail that will be raining down for the sky.
Hail forms as a result of the strong updrafts common in severe weather systems. When a
strong convective cell forms, warm air rises and cool air sinks. If there is a sufficient amount of
supercooled water, accumulation of ice can begin in the clouds.
Rising air will often reach a point in the atmosphere that is below freezing (hence, ice will form).
The ice is suspended in the air by the strong updrafts and will later fall back down. This process
will occur over and over adding layer upon layer to the hailstone. If you cut a hailstone in half,
you would see alternating concentric layers inside it. As the hail falls, it may melt to varying
degrees only to be picked up again and carried high into the atmosphere to re-freeze. Therefore,
very large hailstones form with many repeated cycles.
The SPC then goes in to talk about the wind gusts up to 70 MPH and the Thunderstorm that is
forming. In order to form a thunderstorm, charges are separated when ice crystals rebound off
hail. Charge separation appears to require strong updrafts which carry water droplets upward,
supercooling them to between -10 and -40 °C (14 and -40 °F). These water droplets collide with
ice crystals to form a soft ice-water mixture called hail. Collisions between ice crystals and hail
pellets usually results in positive charge being transferred to the ice crystals, and negative charge
to the hail.
Updrafts drive the less heavy ice crystals upwards, causing the cloud top to accumulate
increasing positive charge. Gravity causes the heavier negatively charged hail to fall toward the
middle and lower portions of the cloud, building up an increasing negative charge. Charge
separation and accumulation continue until the electrical potential becomes sufficient to initiate a
lightning discharge, which occurs when the distribution of positive and negative charges forms a
sufficiently strong electric field.
It then goes on to talk about the potential risk and formation of a tornado. A tornado begins in a
severe thunderstorm called a supercell. A supercell can last longer than a regular thunderstorm.
The same property that keeps the storm going also produces most tornadoes. The wind coming
into the storm starts to swirl and forms a funnel. The air in the funnel spins faster and faster and
creates a very low pressure area which sucks more air (and possibly objects) into it.
The severe thunderstorms which produce tornadoes form where cold dry polar air meets warm
moist tropical air. This is most common in a section of the United States called “Tornado Alley”.
Also, the atmosphere needs to be very unstable as is the case with this storm.
We can see in the doppler image the most of the precipitation/reflectivity in the clouds is
moderate. There are however pockets of extreme precipitation that are not visible on the satellite
image. Although satellite does not give us a good indication of the severity of a storm in terms of
what it is putting out, we are able to see its formation and when it could potentially reach its
maximum severity and what path it will follow.