Overnight Forecast Discussion: April 11, 2012

Overnight Hotspot: Southern Plains
Some severe weather may be ongoing, especially in Texas, as a few frontal boundaries intersect in the state and combine to make for a messy, stormy situation.

Rockies
The mountains will be full of messy weather, with snow in the mountains, rain in lower elevations and some mixing precipitation in between.

West Coast
On the coast, rain will be plentiful overnight, but mountain snows will once again be present, especially in northern California.

Northeast
Some spotty rain showers are likely. No severe weather is expected.

Thunderstorm Outlook for Multi-Day Severe Weather Threat

Latest Information
As of now, indications are for a storm system to shift eastward and into the Plains. As this happens, a warm front already extended out ahead of the storm system will shift northward. At the same time, a cold front located west will move east and intercept the dry line in western Texas.
Due to several factors, including a sharp moisture gradient, high shearing levels and moderate instability, this situation has the potential to induce some intense or even tornadic severe thunderstorms.

Here is the thunderstorm outlook, valid April 12-16.

Key
Yellow: Thunderstorms possible.
Orange: Stronger thunderstorms possible- some may become severe.
Red: Severe thunderstorms likely- a few clusters or several single cells are likely.
Pink: Intense severe weather likely- supercells and/or several intense storm clusters likely.
Blue: Catastrophic severe weather likely. Total destruction of some areas likely.

For those wondering:
Models used for this graphic: GFS, HPC Graphics, ECMWF, SPC SREF
(Models are labeled in order of most influence from left to right.)

Forecast Discussion: April 11, 2012

Hotspot of the Day: South Plains
A low pressure system will be ejecting eastward with a stationary front extending through Texas and along the Gulf Coast. This front will be the focus for severe weather today. Showers and thunderstorms are expected to also form along the trough extending from New Mexico north through Colorado and Wyoming. Both of these areas will have showers and storms to deal with, but it looks like the trough will be the one dealing with severe weather, with damaging winds and hail being the main threats.

West Coast
A storm system now onshore the US will be putting down massive amounts of rain and storms at lower elevations and snow in higher elevations. Some stronger storms are possible with this event today. Snow accumulations may exceed 1 foot above 7000 feet, and 12 inches or under below 7000 feet.

Northeast
An offshore storm system will be putting down rain and snow showers throughout the region today. However, little to no accumulation appears to be expected.

North Plains
A storm system in the region and a warm front out ahead of the system will make for very windy conditions in the Dakotas and east Montana today. This may provoke fire danger.

Southwest
With rain moving through the area in the Southwest, eastern areas of the Southwest will be dry, despite a long trough moving east followed by a cold front. I would anticipate some clouds due to the presence of these disturbances.

East Coast Covered in Red Flag Warnings

The East Coast is currently covered in Red Flag warnings as a lack of rain and windy conditions make for  a rising wildfire danger.

I have heard several reports of wildfires over the last week or so.

If you are near this region and hear of a wildfire close to your area, don't take chances- If it may not hit you, collect several buckets of water around your house to use if the flames get too close. If the fire gets too close for comfort, evacuate immediately. Red Flag Warnings are nothing to mess with.

-Andrew

Early Next Week May Get Interesting

Indications are showing up on the GFS that Monday of next week may get very interesting. Here's why.
As I have been preaching, there is a severe weather risk for Saturday of this upcoming weekend. However, this comes as a major storm system is still in the Rockies mountains. On Monday, this strong storm system will eject east and likely make a big splash, weather wise.

Here's the jet stream forecast for hour 138, or Monday at about 1:00 AM CDT. At that point, the system will be moving east, and the jet stream at 300mb will be screaming along at over 100 knots- a strength usually seen with the worse side of the tornado outbreaks spectrum.
The system does appear to be positively tilted, meaning not as much instability will be present as there could be. However, considering the same system will still be positively tilted this Saturday and risks have already been put out, it may or may not be a substantial player in this situation.

Here's the instability forecast for hour 138- the same timeframe as the image above. At this point, instability is mainly confined to south Texas, where values over 2500 j/kg reside. Farther north, instability as high as 1500 j/kg appears in the works. Now, if there was more instability this situation could get much more intense. However, with limited instability, it won't be devastating.

This is surface to 500mb shear, which is commonly used as an indicator for tornadoes. In this image, we see shearing values above 80 knots, which honestly is a pretty high value. These values are typically reserved for more intense tornadoes. However, with lower instability than what is sufficient, tornadoes that may form may not be as strong as they 'could be'.

6 hour precipitation charts reflect how intense things could get in west Missouri and northeast Oklahoma for this event. These would be serious thunderstorms judging by shear, instability and precipitation as seen above. Below is the area I think people should be 'on watch' for this event.

-Andrew