Brick Tamland Posted September 11, 2015 Share Posted September 11, 2015 I thought instead of cluttering up the fall pattern thread it would be good to have a separate thread for this threat. The latest from RAH. SHORT TERM /SATURDAY AND SATURDAY NIGHT/...AS OF 420 AM FRIDAY...THE MODELS OVERALL REMAIN IN RELATIVELY GOOD AGREEMENT THAT A MID-UPPER TROUGH WILL SHARPEN FROM THE GREAT LAKES TO THE MID-MS VALLEYBY EARLY SAT...BEFORE CLOSING OFF OVER THE OH VALLEY THROUGHSUNDAY...THOUGH TIMING AND AMPLITUDE DIFFERENCES REMAIN. TO ACCOUNTFOR THESE DIFFERENCES AND STILL RELATIVELY LARGE MODEL SPREAD FOR ADAY 2 FORECAST...THE 00Z ECMWF SOLUTION IS PREFERRED AND OFFERS ACOMPROMISE SOLUTION BETWEEN THE FASTER AMERICAN MODELS AND SLOWERCMC AND UKMET. HEIGHT FALLS ALOFT/FORCING FOR ASCENT WILL GRADUALLYINCREASE WITH THE APPROACH OF BOTH THE AMPLIFYING UPPER TROUGH AND ACOUPLED SUB-TROPICAL JET EXIT REGION EMERGING ACROSS THE CAROLINASON SAT. MULTIPLE WEAK AREAS OF LOW PRESSURE WILL CONSEQUENTLYDEVELOP/DEEPEN IN THE LEE OF THE APPALACHIANS - ONE ALONG A WEAKWARM FRONT/LEE TROUGH OVER NORTH-CENTRAL NC...AND ANOTHER ALONG ASECONDARY COLD FRONT INVOF THE NC FOOTHILLS EARLY SAT. LOW PRESSUREWILL THEN CONSOLIDATE AND TRACK NE THROUGH THE MIDDLE ATLANTICSTATES THROUGH SAT NIGHT.ONGOING MORNING CONVECTION WILL BE POSSIBLE IN ASSOCIATION WITH THECLOSE APPROACH OF A LEAD DISTURBANCE/MCV NOW OVER THE MID-MSVALLEY...AHEAD OF BROADER HEIGHT FALLS IN ADVANCE OF THE SYNOPTICTROUGH...AND INVOF A DIFFUSE WARM FRONT LIKELY TO STRETCH NEAR THEVA/NC BORDER EARLY SAT. OTHERWISE...STORMS WILL INCREASE IN COVERAGE--SCATTERED TO NUMEROUS AND IN THE FORM OF BROKEN CLUSTERS/SEMI-DISCRETE MODES-- AHEAD OF AND ALONG THE COLD FRONT DURING THEAFTERNOON AND EVENING...BENEATH STRENGTHENING BACKGROUND FORCINGOUTLINED ABOVE.WHILE THE OVERALL KINEMATICS AND THERMODYNAMICS STILL APPEARFAVORABLE FOR A SEVERE WEATHER EPISODE...CONTINUED LARGER THAN AVGMODEL SPREAD REGARDING THE TIMING AND AMPLITUDE OF THE UPPERTROUGH...AS WELL AS QUESTIONS REGARDING THE DEGREE OF WARM SECTORDESTABILIZATION OWING TO EARLY DAY MULTI-LAYERED CLOUD COVER...LENDHIGHER THAN AVG FORECAST UNCERTAINTY TO THE TIMING/EVOLUTION OFCONVECTION SAT AFT-EVE.IT STILL APPEARS THAT SHEAR VECTORS WILL BE ORIENTED LARGELYPARALLEL TO THE PRIMARY LOW LEVEL BOUNDARIES...WHICH WOULD FAVORQUASI-LINEAR/BROKEN LINE CLUSTER(S) AND SOME SEMI-DISCRETE MODESOWING TO STRENGTHENING DEEP LAYER FLOW...WITH BULK SHEAR VALUES INTHE 35-45 KT RANGE SAT INCREASING WITH TIME INTO THE 40-60 KT RANGEEARLY SAT NIGHT...THOUGH THAT INCREASE MAY BE RENDERED MOOT SINCETHE CONVECTION IS LIKELY TO LARGELY OUTPACE THE STRONGER FLOW ALOFT.ASSOCIATED FORECAST HODOGRAPHS ARE RELATIVELY STRAIGHT...ALBEITLONG...SO ENHANCED LOW LEVEL SHEAR AND ANY CONSEQUENT TORNADO THREATWOULD BE MOST LIKELY INVOF THE WARM FRONT/TRIPLE POINT RETREATINGNORTH THROUGH THE MIDDLE ATLANTIC...WITH AN OTHERWISE PRIMARY THREATOF DAMAGING STRAIGHT LINE WINDS...AND HAIL IN SEMI-DISCRETE(ROTATING) STORMS. Link to comment Share on other sites More sharing options...
Isopycnic Posted September 11, 2015 Share Posted September 11, 2015 Oh hail yes!HAZARDOUS WEATHER OUTLOOKNATIONAL WEATHER SERVICE RALEIGH NC601 AM EDT FRI SEP 11 2015NCZ007>011-021>028-038>043-073>078-083>086-088-089-121015-PERSON-GRANVILLE-VANCE-WARREN-HALIFAX-FORSYTH-GUILFORD-ALAMANCE-ORANGE-DURHAM-FRANKLIN-NASH-EDGECOMBE-DAVIDSON-RANDOLPH-CHATHAM-WAKE-JOHNSTON-WILSON-STANLY-MONTGOMERY-MOORE-LEE-HARNETT-WAYNE-ANSON-RICHMOND-SCOTLAND-HOKE-CUMBERLAND-SAMPSON-601 AM EDT FRI SEP 11 2015THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL NORTH CAROLINA..DAY ONE...TODAY AND TONIGHT.HAZARDOUS WEATHER IS NOT EXPECTED AT THIS TIME..DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.LOW PRESSURE WILL DEVELOP OVER NC LATER TONIGHT AND SATURDAY...THEN GET SWEPT NORTHEASTWARD WITH THE PASSAGE OF A STRONG COLDFRONT LATE SATURDAY AND SATURDAY NIGHT. SEVERE THUNDERSTORMS WILLBE POSSIBLE AHEAD OF AND ALONG THE COLD FRONT SATURDAY AFTERNOONAND EVENING. DAMAGING STRAIGHT LINE WINDS WILL POSE THE PRIMARYHAZARD...WITH A SECONDARY THREAT OF LARGE HAIL..SPOTTER INFORMATION STATEMENT...SPOTTER ACTIVATION MAY BE NEEDED.$$ Link to comment Share on other sites More sharing options...
Isopycnic Posted September 11, 2015 Share Posted September 11, 2015 Tonight A chance of showers and thunderstorms before 11pm, then a slight chance of showers. Mostly cloudy, with a low around 67. Calm wind. Chance of precipitation is 30%. Saturday A chance of showers and thunderstorms, mainly after 1pm. Mostly cloudy, with a high near 84. Light and variable wind becoming southwest 5 to 10 mph in the afternoon. Chance of precipitation is 50%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms. Saturday Night Showers and thunderstorms likely before 2am, then a slight chance of showers. Mostly cloudy, with a low around 61. Northwest wind around 5 mph. Chance of precipitation is 60%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms. Link to comment Share on other sites More sharing options...
downeastnc Posted September 11, 2015 Share Posted September 11, 2015 Nam 4K for tomorrow afternoon Link to comment Share on other sites More sharing options...
SN_Lover Posted September 11, 2015 Share Posted September 11, 2015 You know it's been a horrible severe weather year when a thread is started for a marginal severe weather probability.... Link to comment Share on other sites More sharing options...
downeastnc Posted September 11, 2015 Share Posted September 11, 2015 I would expect to see that upgraded if the modeled threat is still there this evening.......the dynamics involved could produce some really nasty stuff but as usual there are sevel things that have to go the right way and they are most likely waiting to see how the models handle that today before upgrading I could see them going for a small area of enhanced over central and eastern NC for tomorrow afternoon even if the timing is able to work out. Link to comment Share on other sites More sharing options...
Cold Rain Posted September 11, 2015 Share Posted September 11, 2015 Too much cloud cover will limit instability...again. Link to comment Share on other sites More sharing options...
downeastnc Posted September 11, 2015 Share Posted September 11, 2015 Too much cloud cover will limit instability...again. Maybe so, it might mean the difference from a few severe cells and a lot of them......this time of the year though we start looking for more skinny cape high shear type events, the soundings for tomorrow afternoon are definitely severe storm material, but a lot of sun would really help up the cape, but this event could be driven just by the dynamics but there is a lot of things that can wreck it as well. Link to comment Share on other sites More sharing options...
downeastnc Posted September 11, 2015 Share Posted September 11, 2015 The SPC harps on the cloud cover as the reason they don't go with a higher level as of now anyways ...MID-ATLANTIC REGION AND VICINITY... THOUGH PRECEDING PRECIPITATION/CLOUD COVER WILL LIKELY LIMIT DESTABILIZATION ACROSS MUCH OF THE ERN SEABOARD...COOLING ALOFT AHEAD OF THE ADVANCING UPPER TROUGH MAY SUPPORT SUFFICIENT CAPE FOR LOCAL INTENSIFICATION OF AFTERNOON CONVECTION ACROSS THE MID-ATLANTIC REGION AND POSSIBLY AS FAR S AS NRN NC. THOUGH THIS LACK OF CAPE SHOULD HINDER A MORE SUBSTANTIAL SEVERE RISK...MODERATE FLOW ALOFT AHEAD OF THE ADVANCING UPPER SYSTEM MAY SUPPORT A FEW STRONGER CELLS/CLUSTERS/LINE SEGMENTS -- THE STRONGEST OF WHICH MAY PRODUCE LOCALLY GUSTY WINDS AND PERHAPS MARGINAL HAIL DURING THE AFTERNOON AND EARLY EVENING. Link to comment Share on other sites More sharing options...
Brick Tamland Posted September 11, 2015 Author Share Posted September 11, 2015 I don't recall a year like this one where cloud cover has been the culprit so many times in limiting instability with a severe threat. Link to comment Share on other sites More sharing options...
Solak Posted September 11, 2015 Share Posted September 11, 2015 RAH afternoon AFD WHILE MOST OF CENTRAL NC WILL BE SHROUDED IN CLOUDS/FOG EARLY...SHOULD SEE CLOUDS/FOG LIFT BY MID-LATE MORNING. MAY NOT SEE ENOUGH INSOLATION IN THE WEST TO AID IN MUCH DESTABILIZATION. FARTHER EAST...COULD SEE A FEW HOURS OF INSOLATION...AIDING SFC DESTABILIZATION. THE STRENGTHENING JETS SHOULD PROVIDE AMPLE SHEAR SO CHANCES OF ORGANIZED CONVECTION APPEARS FAIRLY HIGH. EXPECT BROKEN BANDS OF CONVECTION WITH DAMAGING WIND THREAT. CANNOT RULE OUT THE POSSIBILITY OF AN ISOLATED SUPERCELL ...ESPECIALLY IF WEAK SFC TROUGH LIES ACROSS THE AREA. TIMING OF CONVECTION STILL FAVORS THE AFTERNOON-EVENING HOURS WITH CONVECTION HIGHEST IN THE WEST BETWEEN 1 PM AND 8 PM...AND IN THE EAST BETWEEN 3 PM AND 9 PM. MAX TEMPS SATURDAY HIGHLY DEPENDENT ON AMOUNT OF SUN AND WHEN CONVECTION OCCURS. FAVOR HIGH TEMPS NEAR 80 FAR NW TO THE MID 80S EAST-SE.SATURDAY NIGHT...SCATTERED CONVECTION WILL PERSIST IN THE EAST THROUGH THE EVENING AND POSSIBLY INTO THE OVERNIGHT HOURS AS THE SFC FRONT PROGRESSES EAST ACROSS THE PIEDMONT. SHOULD SEE OVERALL DOWNTURN IN SHOWER/STORM INTENSITY AFTER 9-10 PM. Link to comment Share on other sites More sharing options...
Brick Tamland Posted September 11, 2015 Author Share Posted September 11, 2015 Just have to see how long it takes the clouds to break tomorrow. Link to comment Share on other sites More sharing options...
Shawn Posted September 11, 2015 Share Posted September 11, 2015 I think this is going to verify here: AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE COLUMBIA SC 240 PM EDT FRI SEP 11 2015 THE NAM DEPICTS MODERATE INSTABILITY FOR SATURDAY AFTERNOON...HOWEVER DIURNAL HEATING MAY BE LIMITED DUE TO CLOUD COVER. SREF PROBABILITIES INDICATE THAT SB CAPE WILL MOST LIKELY BE BETWEEN 500 TO 1000 J/KG. INCREASED DEEP LAYER SHEAR VALUES RANGING FROM 20 TO 30 KTS MAY ALLOW FOR SOME STORM ORGANIZATION. STRONG STORMS ARE POSSIBLE WITH COOLING MID-LEVELS AHEAD OF THE FRONT BUT COVERAGE MAY BE LIMITED WITH ONLY SHALLOW MOISTURE AVAILABLE. Link to comment Share on other sites More sharing options...
calm_days Posted September 11, 2015 Share Posted September 11, 2015 I don't recall a year like this one where cloud cover has been the culprit so many times in limiting instability with a severe threat. This summer has been one with very limited pop-up storm activity also, as well as mesoscale complexes. My memory can be a bit inaccurate but it seems like haze and southeast US pop-up storms have both been on hiatus for a few years now. Link to comment Share on other sites More sharing options...
downeastnc Posted September 12, 2015 Share Posted September 12, 2015 Not as much weather around tonight as they thought maybe and it might help increase the amount of sun tomorrow for a lot of places NAM 4K still aggressive with it Link to comment Share on other sites More sharing options...
Solak Posted September 12, 2015 Share Posted September 12, 2015 This summer has been one with very limited pop-up storm activity also, as well as mesoscale complexes. My memory can be a bit inaccurate but it seems like haze and southeast US pop-up storms have both been on hiatus for a few years now. I don't recall the all to familiar "This afternoon, hazy, hot and humid, with a high of...." in quite a while. Link to comment Share on other sites More sharing options...
Brick Tamland Posted September 12, 2015 Author Share Posted September 12, 2015 Mostly overcast here now, but the sun is trying to peek theough. Just have to wait and see when the clouds burn off. Link to comment Share on other sites More sharing options...
downeastnc Posted September 12, 2015 Share Posted September 12, 2015 The batch of showers moving this way are gonna hit right around peek heating and are exactly the kind of thing that is going to hinder the storms this afternoon. Link to comment Share on other sites More sharing options...
AJF0602 Posted September 12, 2015 Share Posted September 12, 2015 We've had some shine down here at the coast but now mostly cloudy, the timing does suck fot this initial band. Link to comment Share on other sites More sharing options...
oldlogin Posted September 12, 2015 Share Posted September 12, 2015 LC123-121445- /O.CON.KTAE.TO.W.0024.000000T0000Z-150912T1445Z/ TAYLOR FL- 1022 AM EDT SAT SEP 12 2015 ...A TORNADO WARNING REMAINS IN EFFECT UNTIL 1045 AM EDT FOR NORTHEASTERN TAYLOR COUNTY... AT 1022 AM EDT...DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO. THIS DANGEROUS STORM WAS LOCATED OVER PERRY...MOVING NORTHEAST AT 25 MPH. LOCATIONS IMPACTED INCLUDE... PERRY...BUCELL JUNCTION...PERRY-FOLEY AIRPORT...FOLEY AND FENHOLLOWAY. Link to comment Share on other sites More sharing options...
shaggy Posted September 12, 2015 Share Posted September 12, 2015 Not impressed with todays chances when I see a big slug of rain moving into the area this early in the day. Link to comment Share on other sites More sharing options...
Cold Rain Posted September 12, 2015 Share Posted September 12, 2015 The batch of showers moving this way are gonna hit right around peek heating and are exactly the kind of thing that is going to hinder the storms this afternoon. It's the new normal. Link to comment Share on other sites More sharing options...
Brick Tamland Posted September 12, 2015 Author Share Posted September 12, 2015 Maybe the stuff this morning will go through and it will clear up some so it gets more humid and unstable this afternoon. Either that or it will make things more stable. Just seems this scenario had happened over and over this year to keep the severe storms down. Link to comment Share on other sites More sharing options...
Brick Tamland Posted September 12, 2015 Author Share Posted September 12, 2015 It's the new normal. So true. Just crazy how much it has happened this year when there is a chance of severe storms. Link to comment Share on other sites More sharing options...
Brick Tamland Posted September 12, 2015 Author Share Posted September 12, 2015 Looks like easy of US 1 is going to have the best chance of severe storms. Just too much cloud covered here again. NEAR TERM /THROUGH TONIGHT/... AS OF 1050 AM SATURDAY... AS ELUDED TO IN EARLIER FORECAST DISCUSSION...BETTER PARAMETERS FOR STRONG/SEVERE CONVECTION WILL BASICALLY BE CONFINED TO AREAS ALONG AND EAST OF HIGHWAY 1...AND MORE SO OVER SECTIONS OF OUR COASTAL PLAIN AND SANDHILLS (I-95 CORRIDOR). LATEST VISIBLE IMAGERY DEPICTS A THINNING OF THE CLOUD COVER ALONG AND EAST OF I-95. WITH THE THICKER CLOUDINESS (PER AIRCRAFT REPORTS) OVER THE PIEDMONT...SHOULD SEE A DIFFERENTIAL HEATING BOUNDARY NEAR OR EAST OF HIGHWAY 1. THIS BOUNDARY LIKELY TO SHARPEN WITH THE APPROACH OF THE 850-700MB TROUGH LATER THIS AFTERNOON. EAST OF THIS BOUNDARY DESTABILIZATION SHOULD BE SUFFICIENT TO SUPPORT THE INITIATION/MAINTENANCE OF SCATTERED CONVECTION LATER THIS AFTERNOON. EFFECTIVE BULK SHEAR VALUES 30- 40KTS PROJECTED FOR THIS REGION AS WELL. ENOUGH PARAMETERS IN PLACE TO SUGGEST AN INCREASE LIKELIHOOD FOR ORGANIZED CONVECTION IN THE FORM OF CONVECTIVE LINES WITH PRIMARY SEVERE WEATHER HAZARD OF STRONG/DAMAGING WIND GUSTS. CAVEAT TO THIS IS THAT AN AREA OF MOSTLY STRATIFORM LIGHT RAIN IS LIFTING ACROSS THE EASTERN SANDHILLS AND SOUTHERN COASTAL PLAIN AT 14Z. THIS AREA OF LIGHT PRECIP WILL INITIALLY STABILIZE THE NEAR SURFACE AIR MASS...DELAYING CONVECTIVE INITIATION. WHILE LATEST WRF/HRRR GUIDANCE SUGGEST CONVECTION FIRING BY 1-2 PM...THIS MAY BE TOO EARLY BASED ON CURRENT PRECIP SHIELD ACROSS THE SE. CONVECTION MAY NOT FIRE UNTIL CLOSER TO 3-4 PM IF PARTIAL SUNSHINE OCCURS. ACROSS THE BULK OF THE PIEDMONT...EXTENSIVE CLOUDINESS IS INHIBITING INSOLATION AND ASSOCIATED LOW LEVEL DESTABILIZATION. THE APPROACH OF THE AMPLIFYING S/W TO OUR WEST WILL AID TO DESTABILIZE THE ATMOSPHERE ALOFT BY LATE AFTERNOON-EARLY EVENING BUT UNCERTAIN IF THE LOW LEVELS WILL DESTABILIZE ENOUGH TO SUPPORT ANYTHING MORE THAN SCATTERED SHOWERS AND ISOLATED/NON-SEVERE STORMS. FOR NOW WILL MAINTAIN POP FIELD FROM PREVIOUS FORECAST OF DECENT CHANCE WEST TO LIKELY POPS EAST. MAY REFINE THE HWO TO HIGHLIGHT THE BEST CHANCE OF A SEVERE STORM OVER THE EASTERN COUNTIES. Link to comment Share on other sites More sharing options...
AJF0602 Posted September 12, 2015 Share Posted September 12, 2015 The sun popped out here in jville and the radar responded, big storms now around town, with the clouds thinning out it may get interesting later. Link to comment Share on other sites More sharing options...
Brick Tamland Posted September 12, 2015 Author Share Posted September 12, 2015 Yeah, just all depends on the sun popping out. Don't think it is going to happen here. Like Cold Rain said, the new normal this year. Looks like once again the storms I got Thursday night are going to be better than anything I get today when there is talk of severe weather. Link to comment Share on other sites More sharing options...
Isopycnic Posted September 12, 2015 Share Posted September 12, 2015 Small showers and storms are starting to pop over the western piedmont Link to comment Share on other sites More sharing options...
Solak Posted September 12, 2015 Share Posted September 12, 2015 Still got some of us in the 'marginal risk'... Link to comment Share on other sites More sharing options...
yotaman Posted September 12, 2015 Share Posted September 12, 2015 Had a very fast moving storm come thru about 30 minutes ago. No lightning but had 30 to 40 mph winds with intense rain. picked up .48" in about 15 minutes. Sun is back out. Link to comment Share on other sites More sharing options...
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