Severe Storms Forecast: 4/19/18

Follow up from yesterday:  no severe reports received.

The Storm Prediction Center (SPC) has issued a Marginal Risk today for parts of western New Mexico, including Rio Rancho (my home!).  There is less than a 2% chance of tornadoes anywhere in the country.  Large hail and damaging winds will be the primary threats from these storms.

Synoptically speaking, the 250 mb NAM chart shows a small but vigorous shortwave trough entering New Mexico from the west.

The 500 mb NAM chart shows strong vorticity lagging behind the trough.  It will only be as far as Arizona when the trough is over New Mexico.

The 700 mb NAM chart shows several pockets of rapidly-rising air over New Mexico by 00 Z.

The 850 mb NAM chart shows no strong thermal advection in either direction.

The surface dewpoints (NAM) show moisture advecting up the Rio Grande River Valley this afternoon.  Notice the spike of green running north.

The NAM shows that Convective Available Potential Energy (CAPE) will be limited.  However, given the time of year and the location, it may be sufficient for severe thunderstorms.

The NAM shows the Supercell Composite is non-zero, particularly just west of the Rio Grande River Valley.

The NAM also shows non-zero Significant Tornado numbers, which is a surprise to me.  On the other hand, shear is good, so if strong storms form and persist, the shear will only increase the possibility of rotating storms.

Overall, I think a few storms are possible and gusty winds will be the primary threat, with some hail possible.  These low CAPE, high shear systems are always a little awkward to predict.  By standard textbook meteorology, storms should not be likely at all with so little CAPE.  However, there is a funny thing at the higher elevations (and latitudes for that matter) where lower CAPE is needed to form storms.  CO, WY, MT, NM, ND, SD, and MN often have severe storms with less than 1000 J/kg of CAPE.  That would be a ho-hum day in TX or OK.

Thank you for reading my forecast.

The upper air soundings and mesoscale analysis plots are from the <a href=”; target=”_blank”>Storm Prediction Center</a> website.
The forecasted upper air soundings are from <a href=”; target=”_blank”></a>.
The surface observation and upper level charts are from <a href=”; target=”_blank”>Unisys Weather</a>.
The satellite data is from <a href=”; target=”_blank”>NASA – MSFC</a>

About highplainschasing

This blog is about my tales in storm chasing. My name is Seth Price and I am an instrumentation instructor at New Mexico Tech. My amateur radio call sign is N3MRA.
This entry was posted in Follow Up, Practicing Concepts, Predictions, Satellite Imagery, Severe Weather and tagged , , , , , , , . Bookmark the permalink.

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