Here is todays thunderstorm and convection outlook issued by The Storm Prediction Center in Norman, Oklahoma.... DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1124 AM CDT FRI AUG 01 2014 VALID 011630Z - 021200Z ...NO SVR TSTM AREAS FORECAST... ...SUMMARY... THUNDERSTORMS...INCLUDING SOME WITH A MARGINAL SEVERE THREAT...WILL OCCUR OVER THE UPPER MISSISSIPPI VALLEY AND GREAT LAKES...WESTERN SOUTH DAKOTA INTO NEBRASKA...AND FROM PARTS OF GEORGIA INTO THE CAROLINAS. ...SYNOPTIC SETUP... LITTLE CHANGE TO AMPLIFIED WRN RIDGE/ERN TROUGH PATTERN EXPECTED THROUGH SAT. BROAD ERN TROUGH EXTENDING SSW FROM SLOWLY-PROGRESSIVE JAMES BAY LOW WILL PERSIST OVER THE OH AND MS VLYS. WITHIN THE TROUGH...ONE LOW-AMPLITUDE/ELONGATED IMPULSE NOW OVER GA AND THE SRN APPALACHIANS WILL SHEAR NNE ACROSS THE CAROLINAS TO THE MID-ATLANTIC CST LATER TODAY/TNGT...WHILE UPSTREAM DISTURBANCE NOW OVER MN CONTINUES SE INTO THE MID MS VLY. FARTHER W...SATELLITE SHOWS SEVERAL DISTURBANCES TOPPING THE WRN RIDGE. THE ONE NOW IN ORE SHOULD DRIFT NEWD AND WEAKEN...WHILE LOOSELY-ORGANIZED FEATURE IN SRN SK/NE MT CONTINUES ESE INTO THE WRN DAKOTAS. FEATURES WILL REMAIN VERY WEAK AT THE SFC. SHALLOW SW-NE BOUNDARY MARKING THE NWRN FRINGE OF WRN ATLANTIC/CARIBBEAN AIR...NOW STALLED ALONG THE SRN NC CST...SHOULD DRIFT A BIT INLAND ACROSS FAR ERN NC AND FAR SERN VA TODAY/TNGT IN RESPONSE TO APPROACHING UPR IMPULSE. OTHERWISE...POORLY-DEFINED LEE TROUGH WILL REMAIN QSTNRY OVER THE NRN HIGH PLNS. ...GA/CNTRL-ERN CAROLINAS INTO SE VA TODAY/TNGT... NUMEROUS SHOWERS AND WDLY SCTD TSTMS ARE EXPECTED OVER THE PIEDMONT/CSTL PLN OF GA...THE CAROLINAS...AND SE VA THROUGH EARLY SAT. ACTIVITY WILL BE FOSTERED BY ASCENT DOWNSTREAM FROM SHEARING UPR IMPULSE AND RICH MOISTURE /ESPECIALLY ALONG THE CST...WHERE PW WILL REMAIN AOA 2 INCHES/. MODEST SFC HEATING AND TIMING OF UPR IMPULSE SUGGEST COVERAGE/INTENSITY MAY PEAK LATER THIS AFTN INTO TNGT OVER ERN NC AND SE VA. LOW-LVL LAPSE RATES WILL REMAIN WEAK OVER MUCH OF THE REGION GIVEN EXISTING CLOUDS/RAIN. BUT A CORRIDOR OF ENHANCED LOW-LVL DIRECTIONAL SHEAR...SAMPLED ATTM BY THE MHX VWP...WILL PERSIST NEAR AFOREMENTIONED FRONT. AS THAT BOUNDARY DRIFTS A BIT NWWD LATER TODAY...AND AS BAND OF SLIGHTLY STRONGER 700-500 MB FLOW/ASCENT OVERSPREAD REGION AHEAD OF UPR DISTURBANCE...A FEW SHOWERS/STORMS MAY ACQUIRE LOW-LVL ROTATION GIVEN CONFLUENT/LOW LCL/MOISTURE-RICH ENVIRONMENT. RELATIVELY WEAK BACKGROUND PRESSURE FIELD SHOULD KEEP LOW-LVL WINDS...AND MAGNITUDE OF DIRECTIONAL SHEAR...FAIRLY MODEST. BUT SOME POTENTIAL WILL EXIST FOR OCCASIONAL STORM-SCALE VORTICITY/CONVERGENCE AUGMENTATION. THUS...THERE WILL BE A CONDITIONAL RISK FOR A COUPLE TORNADOES...EVEN THOUGH THE OVERALL THREAT STILL APPEARS TOO DISORGANIZED/ISOLD/TRANSIENT TO WARRANT AN OUTLOOK UPGRADE ATTM. IF AN UPGRADE TO SLGT RISK WERE TO BE REQUIRED LATER TODAY...IT MOST LIKELY WOULD BE FOR FAR ERN/NERN NC. FARTHER W/SW...WHERE SFC HEATING WILL BE SOMEWHAT GREATER...PRECIP-LOADING MAY YIELD A DMGG GUST OR TWO ALONG SECONDARY WIND SHIFT LINE MOVING E ACROSS CNTRL NC...CNTRL/ERN SC...AND ERN GA THIS AFTN. ...UPR MS VLY THIS AFTN... STRONG SFC HEATING WILL OCCUR TODAY BENEATH MN UPR IMPULSE AS IT CONTINUES SEWD INTO PARTS OF WI/IL AND IA...SUPPORTING WDLY SCTD AFTN TSTM DEVELOPMENT IN ZONE OF WEAK LOW-LVL CONVERGENCE/MODEST MOISTURE. MID-LVL LAPSE RATES WILL BE FAIRLY STEEP...SUGGESTING POTENTIAL FOR HAIL IN STRONGER UPDRAFTS. BUT WEAK SHEAR SHOULD KEEP ANY SVR THREAT TRANSIENT/ISOLD. ...NRN PLNS THIS AFTN/EVE... MID-LVL LAPSE RATES/ASCENT WILL INCREASE OVER WRN PARTS OF THE NRN PLNS TODAY...DOWNSTREAM FROM SK/MT UPR TROUGH. COUPLED WITH STRONG SFC HEATING...MODEST LOW-LVL MOISTURE /PW .75-1.00 INCH/...AND WEAK UPLIFT ALONG LEE TROUGH/TERRAIN...SETUP MAY YIELD WDLY SCTD AFTN STORMS CAPABLE OF STRONG GUSTS AND PERHAPS HAIL GIVEN INVERTED-V SUB CLOUD LAYER THERMODYNAMIC PROFILES.
Posted on: Fri, 01 Aug 2014 18:38:38 +0000