The Chase Is On

Well, now that the low pressure system has finally begun to fire storms over the Puget Sound, they will be moving North/ North East by this afternoon. Our chase day so far has started off with lighting outside our window and torrential rains that just do not seem to want to go away. As I stated yesterday, the storms of the Central Cascades region will begin to develop from 18z to 19z, so that gives us our time to pack and prepare the vehicle. Because supercells become more likely from 4 to 7pm, we shall be leaving our current location around 3pm.

{SPC Friday Tornado Outlook}

                This morning the SPC had released their severe weather outlook, giving our targeted area a 2% chance of seeing a tornado (and that is as good as it gets throughout the entire nation) within fifteen miles of any given point. This is due to sufficient shear standing at thirty to fifty knots and large CAPE of 1000+ J/km.

{SPC FridaySevere Hail Outlook}



{SPC Friday Severe Wind Outlook}




At this moment the SPC has issued their current mesoscale discusion...

MESOSCALE DISCUSSION 1513
   NWS STORM PREDICTION CENTER NORMAN OK
   1132 AM CDT FRI JUL 20 2012 
   AREAS AFFECTED...PARTS OF NE OREGON/ERN WASHINGTON AND ADJACENT

   IDAHO 

   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

   VALID 201632Z - 201800Z

   PROBABILITY OF WATCH ISSUANCE...60 PERCENT  

   SUMMARY...TRENDS ARE BEING MONITORED FOR AN INCREASING SEVERE THREAT

   THAT COULD REQUIRE A WATCH BY EARLY AFTERNOON.  

   DISCUSSION...MID-LEVEL FLOW STILL APPEARS GENERALLY SUBSIDENT ALONG THE EASTERN FRINGE OF A 50-60 KT SOUTHERLY 500 MB JET STREAK LIFTING THROUGH EASTERN OREGON AND WASHINGTON.  BUT CLEAR TO PARTLY CLOUDY CONDITIONS ARE ALLOWING FOR CONSIDERABLE INSOLATION...AND DESTABILIZATION OF A MOIST BOUNDARY LAYER ACROSS THE WALLOWA/BLUE MOUNTAINS VICINITY NORTHWARD THROUGH MUCH OF THE COLUMBIA BASIN. LATEST OBJECTIVE ANALYSES AND MODEL FORECASTS SUGGEST THAT CAPE IS IN THE PROCESS OF BECOMING MODERATELY LARGE...ON THE ORDER OF 1000 TO 2000 J/KG...AND THIS IS EXPECTED TO BECOME SUPPORTIVE OF VIGOROUS CONVECTIVE DEVELOPMENT AS MID-LEVEL FORCING FOR ASCENT INCREASES AHEAD OF AN UPPER TROUGH BEGINNING TO LIFT NORTHEAST OF THE CASCADES.  GUIDANCE INDICATES STORM DEVELOPMENT MAY INITIATE AS EARLY AS 18-19Z...BEFORE INCREASING IN COVERAGE/INTENSITY DURING THE AFTERNOON.  VERTICAL SHEAR WILL BE MORE THAN SUFFICIENT FOR SUPERCELLS WITH AT LEAST A RISK FOR LARGE HAIL AND LOCALLY DAMAGING WIND GUSTS.  LOW-LEVEL HODOGRAPHS ARE MORE UNCERTAIN...BUT AN ISOLATED TORNADO MAY NOT BE OUT OF THE QUESTION...PARTICULARLY EAST OF THE SURFACE LOW...NEAR/NORTH OF THE YAKIMA VALLEY.