SPC Day 1 Fire Weather Outlook

SPC Day 1 Fire Weather Outlook
DAY 1 FIRE WEATHER OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0229 AM CDT SAT AUG 18 2012 VALID 181200Z - 191200Z ...CRITICAL FIRE WEATHER AREA FOR NERN CA...NWRN NV...CNTRL/ERN ORE... ...SYNOPSIS... AN UPPER TROUGH CENTERED OVER HUDSON BAY WILL REMAIN STAGNANT OVER THE ERN HALF OF THE NATION...WHILE A BREAK DOWN OF THE RIDGE OCCURS TO THE WEST. THE THREAT OF LIGHTNING-BASED IGNITIONS WILL INCREASE ACROSS PORTIONS OF THE NORTHWEST AS THIS OCCURS. MEANWHILE AT THE SURFACE...A FRONT WILL REMAIN NEARLY STATIONARY ACROSS THE MID ATLANTIC...THE SOUTHEAST AND SRN PLAINS. ...NERN CA...NWRN NV...CNTRL/ERN ORE... NOCTURNAL CONVECTION IS ONGOING AS OF 07Z ACROSS COASTAL NRN CA NWD INTO S CNTRL ORE. THE ONGOING CONVECTION APPEARS TO BE ASSOCIATED WITH A SERIES OF VORTICITY MAXIMA ROTATING NWD AHEAD OF A PARENT OFFSHORE LOW...WITH ONE NOTED ON 07Z WV IMAGERY OVER CNTRL CA AND ANOTHER ACROSS S CNTRL ORE. AN ADDITIONAL AREA OF IMPLIED ASCENT IS NOTED ALONG THE PACIFIC NORTHWEST COAST. ALTHOUGH SOME CONVECTIVE DEBRIS FROM DECAYING THUNDERSTORMS MAY HINDER GREATER DAYTIME SURFACE HEATING ACROSS PORTIONS OF CNTRL ORE...BREAKS IN THE CLOUDS WILL LIKELY BE SUFFICIENT ENOUGH FOR DESTABILIZATION AND ANOTHER ROUND OF THUNDERSTORMS TO OCCUR. CURRENT FORECASTS SUGGEST THAT THE AFOREMENTIONED VORT LOCATED ACROSS CNTRL CA WILL BE THE PRIMARY INITIATOR OF AFTERNOON/EVENING CONVECTION...PARTICULARLY ACROSS THE HIGHER TERRAIN OF NRN CA AND ORE...WHERE ABUNDANT LIGHTNING IS POSSIBLE...AS WELL AS WETTING RAINFALL. HOWEVER...EAST OF THE CASCADES...THE PRECEDING HOT AND DRY WEATHER WILL MAINTAIN A DRY SUBCLOUD LAYER...LEADING TO A GREATER CONCERN FOR LIGHTNING-BASED IGNITIONS AND GUSTY WINDS AS STORMS PROGRESS NEWD THROUGH CNTRL ORE. FARTHER E...ALTHOUGH A DRIER AIR MASS AND MEAGER INSTABILITY OVER ERN ORE/SWRN ID MAY LIMIT COVERAGE OF STORMS...ISOLATED DRY STORMS CANNOT BE RULED OUT. NOCTURNAL CONVECTION WILL ONCE AGAIN BE POSSIBLE AS HEIGHTS CONTINUE TO FALL OVERNIGHT. ...CNTRL/ERN WA... 00Z SLE SOUNDING SHOWS MOISTURE ALREADY INCREASING ALONG THE COAST...WITH A MEASURED PWAT VALUE OF 1.18 INCH. ALTHOUGH LIGHTNING WILL LIKELY OCCUR ALONG AND W OF THE CASCADES...WETTING RAIN IS ANTICIPATED WITH THE ACTIVITY. E OF THE CASCADES...LIGHT UPSLOPE LOW-LEVEL SELYS WILL LIKELY CONTRIBUTE TO THE DEVELOPMENT OF A FEW DRIER THUNDERSTORMS...WITH ADDITIONAL STORMS POSSIBLE ALONG A THERMAL TROUGH OVER THE COLUMBIA BASIN. HOWEVER...THE GREATEST HEIGHT FALLS ARE EXPECTED OVERNIGHT...SUPPORTING A THREAT OF NOCTURNAL CONVECTION...PARTICULARLY WITH ANY ONGOING ACTIVITY PROGRESSING NWD OUT OF CNTRL ORE. BY THAT TIME...PWATS WILL HAVE INCREASED TO NEAR 0.75 TO 1 INCH...LEADING TO ONLY A NARROW TEMPORAL THREAT OF DRIER STORMS. ..HURLBUT.. 08/18/2012 ...PLEASE SEE WWW.SPC.NOAA.GOV/FIRE FOR GRAPHIC PRODUCT... Read more

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