Northeast Oregon in SLIGHT RISK area today

The Storm Prediction Center has extreme NE Oregon in a “slight risk” area for severe thunderstorms this afternoon/evening.

http://www.spc.noaa.gov/products/outlook/day1otlk.html

day1otlk_1630
This is due to the cool upper-level disturbance moving across the Pacific Northwest producing great lift and shear in the atmosphere.  It’ll be tough to get anything other than a rumble or flash of lightning anywhere west of a Hermiston to Bend line.  But with better lift in Wallowa County and possibly Union/Baker counties some storms may get organized enough to produce strong/damaging wind.  It’s far more likely across northern Idaho and Montana this evening though.  Here is a snippet from their discussion:

...STEEP MID LEVEL LAPSE RATES AND LOW LEVEL DIABATIC HEATING FROM ERN OREGON ACROSS THE NRN ROCKIES AHEAD OF THE ADVANCING COLD FRONT WILL RESULT IN A DEEP SURFACE-BASED MIXED LAYER WITH CAPE REACHING 300-500 J/KG.  CONSENSUS MODEL GUIDANCE INCLUDING CONVECTION-ALLOWING MODELS INDICATE WIDELY SCATTERED HIGH-BASED STORMS WILL DEVELOP ALONG A CORRIDOR FROM NERN OREGON INTO WRN MT DURING THE 21-00Z PERIOD...WITH ACTIVITY SPREADING ENEWD INTO TONIGHT.  STRONG DEEP LAYER SHEAR WILL ENHANCE STORM ORGANIZATION WITH POTENTIAL FOR A FEW BOWING SEGMENTS OR SUPERCELLS TO OCCUR WITH STRONGER STORMSCAPABLE OF PRODUCING DAMAGING WIND GUSTS OR MARGINALLY SEVERE HAIL. 

What is a "severe thunderstorm?".  
Here's the official definition from the SPC folks:  The term severe thunderstorm refers to a thunderstorm producing hail that is at least quarter size, 1 inch in diameter or larger, and/or wind gusts to 58 mph or greater, and/or a tornado. Although lightning can be deadly, the NWS doesn't use it to define a severe thunderstorm. If it did, every thnderstorm would be severe, by definition. Also, excessive rainfall may lead to deadly flash flooding, but heavy rain is not a severe criterion either. The flood threat is handled through a separate set of watches and warnings from your local NWS forecast office.

West of the Cascades we’ll just see some vigorous showers (brief downpours, possible flash of lightning/rumble of thunder) through this evening since most of the action here is to our north up in Washington.  What a change though!  I was just thinking the other day how little of the cold showers & sunbreaks weather we’ve seen since March.

I’ll blog later about the coming payback time…I mean payback for all the warm and dry weather the past three weeks!

Chief Meteorologist Mark Nelsen

28 Responses to Northeast Oregon in SLIGHT RISK area today

  1. LongtimeLurker says:

    I love how the humidity was blown out of here! Much more comfortable this afternoon.

  2. Tyler Mode in Battle Ground says:

    Peak wind of 27 mph here. Peak rainfall rate of 1.49″ with a downpour around 2 pm.

    It’s amazing watching how much the trees can bend without actually breaking.

  3. pappoose in scappoose says:

    NATIONAL WEATHER SERVICE PORTLAND OR
    300 PM PDT MON MAY 13 2013

    SHORT TERM…A LOOP OF VISIBLE SATELLITE IMAGERY SHOWS AN UPPER LEVEL LOW PRESSURE MOVING NORTHEASTWARD INTO THE OLYMPIC PENINSULA. A
    LOOSE LINE OF CONVECTION HAS DEVELOPED ALONG THE LEADING EDGE OF A MID LEVEL VORT MAX SWINGING NORTHEASTWARD UNDERNEATH THE AFOREMENTIONED UPPER LEVEL LOW PRESSURE. INSTABILITY GENERALLY
    REMAINS DEEPEST OVER WASHINGTON SO LIGHTNING HAS BEEN PRIMARILY CONFINED TO THE VERY NORTHERN PORTION OF OUR CWA. WITH THAT SAID…A STRIKE DID OCCUR NEAR WOODLAND WASHINGTON AND A SPOTTER REPORTED HEARING THUNDER IN SE PDX. SOME ADDITIONAL CONVECTION WILL LIKELY FIRE BEHIND THIS INITIAL LINE AS THE LOWER ATMOSPHERE DESTABILIZES
    ONCE AGAIN UNDER MORE SUNSHINE. AS A RESULT…ANOTHER ROUND OR TWO OF INTENSE SHOWERS AND ISOLATED THUNDERSTORMS WILL BE POSSIBLE…PARTICULARLY ACROSS OUR FAR NORTHERN ZONES.

  4. WEATHERDAN says:

    Partly sunny and 68 here in Salem. No precip yesterday and only .02 today. So far not much payback just normal May weather. Enjoying the very nice spring. Next two weeks looks mild with some light precip. But no supercool or superwet weather either.

  5. pappoose in scappoose says:

    Wander on down here, you Donkeys!

  6. amy says:

    Albany,Or has some wind, with some small branches down. Feels nice to me though.

  7. *BoringOregon* says:

    Wow, the weather channel just said a Severe Thunderstorm Watch for eastern Oregon golf ball size hail !!

  8. David B. says:

    Thunderstorm just starting on Bainbridge Island (about 5 miles west of Downtown Seattle).

  9. just had that downpour roll through. that dark red blob on radar. took some video, uploading to youtube now. impressive.

  10. *BoringOregon* says:

    40% chance is better the 0% :).

  11. Jordan (Raleigh Hills, 420') says:

    Feels like thunderstorms outside! Something awfully heavy just popped up NW of Kelso. Lookin pretty fierce to me!

  12. Timmy_Supercell (Klamath Falls @ 4200') says:

    It looks like part of the description is cut off in the middle..

    And finally a slight risk! A bit more common in NE Oregon but west of the cascades we seldom see these.

  13. PaulO says:

    Thanks Mark looking forward to the payback 🙂

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