Oct 17, 2013 2000 UTC Day 1 Convective Outlook | |||||||||
Updated: Thu Oct 17 20:00:43 UTC 2013 ( | ) | |||||||||
Probabilistic to Categorical Outlook Conversion Table |
Categorical Graphic | |||||||||
---|---|---|---|---|---|---|---|---|---|
Probabilistic Tornado Graphic | |||||||||
Probability of a tornado within 25 miles of a point. Hatched Area: 10% or greater probability of EF2 - EF5 tornadoes within 25 miles of a point. |
|||||||||
Probabilistic Damaging Wind Graphic | |||||||||
Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point. Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point. |
|||||||||
Probabilistic Large Hail Graphic | |||||||||
Probability of hail 1" or larger within 25 miles of a point. Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point. |
|||||||||
| |||||||||
SPC AC 171956 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0256 PM CDT THU OCT 17 2013 VALID 172000Z - 181200Z ...NO SVR TSTM AREAS FORECAST... ...DISCUSSION... NO SUBSTANTIAL CHANGES ARE BEING MADE TO THE PRIOR FORECAST ATTM...ASIDE FROM SHRINKING MOST THUNDER AREAS. A NARROW BAND OF LOW-TOPPED CONVECTION IS ONGOING ATTM FROM WRN PA SSWWD INTO SRN WV/FAR WRN VA...AND THE LINE WILL CONTINUE SHIFTING EWD WITH TIME AS THE FRONT AND ASSOCIATED UPPER VORT MAX ADVANCE. WHILE DESTABILIZATION AHEAD OF THE FRONTAL CONVECTION HAS BEEN MINIMAL...STRENGTH OF FLOW ALOFT MAY STILL PERMIT A FEW STRONGER GUSTS TO OCCUR LOCALLY AS THE CONVECTION PASSES FROM W-E THROUGH THE END OF THE PERIOD. ..GOSS.. 10/17/2013 .PREV DISCUSSION... /ISSUED 1109 AM CDT THU OCT 17 2013/ ...SYNOPSIS... A BROAD CYCLONIC FLOW REGIME WILL BE MAINTAINED OVER THE CONUS WITH A BELT OF STRONG MID AND UPPER-LEVEL FLOW STRETCHING FROM THE CNTRL/SRN PLAINS THROUGH THE NORTHEAST AND MID ATLANTIC STATES. EMBEDDED WITHIN THIS HIGHER MOMENTUM AIR STREAM...A SHORT-WAVE TROUGH OVER THE MIDWEST WILL TRANSLATE NEWD INTO THE ST. LAWRENCE VALLEY BY 18/12Z. OTHER MORE PROMINENT VORTICITY MAXIMA WILL TRACK FROM THE NRN PLAINS INTO UPPER GREAT LAKES...AND FROM THE NRN INTER-MOUNTAIN REGION TO CNTRL/SRN ROCKIES DURING THE D1 PERIOD. IN THE LOW LEVELS...A SURFACE CYCLONE ASSOCIATED WITH THE MIDWEST SHORT-WAVE TROUGH WILL DEEPEN WHILE DEVELOPING NEWD FROM THE CNTRL APPALACHIANS THROUGH CNTRL PA LATE THIS AFTERNOON BEFORE REACHING MAINE EARLY FRI. MEANWHILE...A TRAILING COLD FRONT WILL ADVANCE EWD/SEWD TO OFF THE MID ATLANTIC COAST. ...CNTRL APPALACHIANS TO NEW ENGLAND THIS AFTERNOON INTO TONIGHT... BOTH FORCING FOR ASCENT AND VERTICAL SHEAR WILL INCREASE WITH THE APPROACH OF THE MIDWEST/OH VALLEY SHORT-WAVE TROUGH. HOWEVER... MORNING VISIBLE SATELLITE IMAGERY INDICATES AN EXPANSIVE CLOUD SHIELD ATTENDING THIS SYSTEM WHICH WILL PROGRESSIVELY OVERSPREAD THE REGION TODAY...LIMITING THE DEGREE OF AIR MASS DESTABILIZATION AHEAD OF THE COLD FRONT. LATEST CONVECTION-ALLOWING MODEL GUIDANCE SUGGESTS THAT A LOW-TOPPED CONVECTIVE BAND --WITH A FEW EMBEDDED TSTMS-- WILL BECOME INCREASINGLY POSSIBLE BY LATE AFTERNOON OR EARLY EVENING FROM CNTRL/ERN PA INTO NRN VA AS THE STRONGER FORCING FOR ASCENT/DCVA ASSOCIATED WITH THE SHORT-WAVE TROUGH LINKS WITH THE FRONTAL UPLIFT. SHOULD SUFFICIENT DESTABILIZATION OCCUR TO SUPPORT SURFACE-BASED STORM DEVELOPMENT...THE DOWNWARD MOMENTUM TRANSFER OF AN INCREASINGLY STRONG TROPOSPHERIC WIND FIELD MAY PROMOTE LOCALLY STRONG WIND GUSTS WITH THE CONVECTIVE BAND. ...CNTRL/ERN GULF COAST THIS AFTERNOON... ISOLATED TO WIDELY SCATTERED TSTMS WILL BE POSSIBLE THIS AFTERNOON ALONG AND AHEAD OF THE COLD FRONT WHERE SEASONABLY MOIST CONDITIONS WILL YIELD MLCAPE OF 500-1000 J/KG. WHILE A STRONG STORM OR TWO IS POSSIBLE...MARGINAL AMOUNTS OF INSTABILITY AND VERTICAL SHEAR WILL PRECLUDE SEVERE WEATHER POTENTIAL. ...CNTRL/SRN PLAINS TONIGHT... THE SEWD PROGRESSION OF A SHORT-WAVE TROUGH THROUGH THE CNTRL PLAINS WILL CONTRIBUTE TO THE ENHANCEMENT OF A NOCTURNAL LLJ AND THE POLEWARD RETURN OF A PARTIALLY MODIFIED AIR MASS THROUGH THE SRN HIGH PLAINS. THIS MOISTURE RETURN WILL OCCUR BENEATH A PLUME OF STEEP MIDLEVEL LAPSE RATES...BOOSTING MUCAPE TO 500-1000 J/KG. ISOLATED TO WIDELY SCATTERED ELEVATED TSTMS WILL BECOME INCREASINGLY POSSIBLE WITHIN THIS REGIME IN THE 18/09-12Z TIME FRAME AS FORCING FOR ASCENT IS ENHANCED BY WAA/ISENTROPIC AT THE TERMINUS OF THE LLJ. NO SEVERE WEATHER IS EXPECTED. CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z |