Severe Weather Discussion for April 20 – 26, 2015.

Severe Weather Discussion for April 20 – 26, 2015.
Issued: 04/19/2015.

Highlights:

– Severe thunderstorms are possible Tuesday, Wednesday and Friday. There is a chance of thunderstorms Thursday, but severe weather potential looks lower than the other two days.

– Temperatures will be in the upper 60s Monday – Tuesday, upper 70s Wednesday, mid 70s Thursday, near 80F Friday and mid 70s Saturday – Sunday.

Probabilities:

– Severe Thunderstorms: 35%
– Storm Chase: 50%

Discussion:

Southern stream shortwave trof currently over Oklahoma will move east-northeast and phase with northern stream system. This will create a large closed low over the Great Lakes by the middle of this week. Shortwave ridging will dominate just west of the state, with this area in between the Great Lakes low and the shortwave ridge Tuesday-Thursday. South winds are expected to turn as the cold front moves off allowing moisture turn on Tuesday. Thunderstorms are possible on Tuesday with SPC having a small slight risk in SW OK for severe thunderstorms. The threat appears limited but some large hail is certainly possible. Winds are decent on Wednesday and moisture should improve. Models have backed off on pushing moisture way south and now bring 60F + dewpoints back into the state on Wednesday. As such, there is a threat for severe thunderstorms Wednesday afternoon across a large part of Oklahoma. The threat looks to be hail at this point, but additional threats could develop as we get a better idea of atmospheric evolution that day.

Atmosphere becomes progressive on Thursday with Great Lakes system shifting east and southwest US system ejecting northeast towards Oklahoma. EC/GFS agree that SW US system will move across Oklahoma on Friday with impressive winds speeds aloft. The unknown issues are surface moisture and temperature. Currently the EC develops decent CAPE across much of Oklahoma but only a narrow tongue of good moisture. Either way, Friday does have potential to be a higher impact severe weather day and will be monitored. This also has the best chase potential, as long as the threat stays in western Oklahoma. Upper system moves slowly by on Saturday and Sunday. These days look pleasant and rain free ATTM.

Not sure numbers are that good, but don’t agree with models or NWS. So, I’ll just let them ride, Friday may be too high but then again we’ll see what happens.

Verification:

OKC Temps for 04/13 – 04/19 –

My Numbers: mid 60s, low 60s, low 70s, mid 70s, low 70s, low 70s and low 70s.
NWS Numbers: mid 60s, low 60s, low 70s, mid 70s, low 70s, low 70s and 70F.
Actual: 69F, 57F, 71F, 78F, 75F, 78F and 69F.

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