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Potential thunderstorms/svr thunderstorms Thread


tombo82685

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Nothing new here. Showers died out as usual over the Blue Mts. It is so disgusting. For three weeks now, hardly any rain, no severe threats and my yard is turning brown. The mornings consist of crappy stratus covered skies. The sun breaks out, in the early afternoon and looks promising for t-storm development but it falls apart goes to the east of us. It has been a long time since I have seen a weather pattern like this in June. What is really weird is that we are 5-10 degrees hotter than the airport because the sun is out in the afternoon while it has been cloudy and raining at ABE. This has happened many days so far in June. Like yesterday, my thermometer hit 91 degrees and it felt like 91 degrees, My thermometer is usually pretty accurate and is close to ABE reading so my thermometer is not off. I am sure this condition applies to northern Montgomery and eastern Berks counties as well

Hit 90 degrees again today. Sun is out. I see the the weather forecasts are going to hell again for rain chances tomorrow. I hope the moisture and storms in the Tenn Valley can make it this far north before falling apart later tonight. We sure can use the rain. I could have peed more than what we got early this morning.

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Had the chance to observe a multicell complex/struggle today over delaware county. Was golfing at springfield and saw the thunderhead. Impressive looking 1 minute, dying out the next minute. Got a quick rain shower out of it, but not enough to wet the pavement. Anyhow, here's mt. Holly's 814pm thoughts.

A TROUGH ON THE LEE SIDE OF APPALACHIANS LOOKS TO SET UP ACROSS OUR

AREA AND COULD BE THE SOURCE OF LIFT NEEDED TO GET THUNDERSTORMS

GOING IN THE AFTERNOON. VERTICAL SHEAR IS VERY LIMITED AND STORMS

WILL LIKELY BE SLOW MOVERS AND MULTI CELLULAR IN NATURE.

PRECIPITABLE WATERS ALSO BEGIN TO INCREASE AND RISE IN EXCESS OF 2

INCHES BY WEDNESDAY AFTERNOON/EVENING. WHEN PWATS GET OVER 2 INCHES

IN JUNE IT INDICATES A DEPARTURE GREATER THAN 2SD OF NORMAL AND IS A

GOOD INDICATOR THAT DEVELOPING STORMS WILL LIKELY BE EFFICIENT

RAINMAKERS. THEREFORE, THE POTENTIAL FOR FLASH FLOODING WILL ALSO

INCREASE. AS FAR AS FLASH FLOODING GOES, THE MOST PRONE AREAS REMAIN

ACROSS NORTHERN AND CENTRAL NEW JERSEY AND THE SOUTHERN POCONOS.

LATEST GUIDANCE SHOWS THE BULK OF THE PRECIPITATION STAYING OFF TO

OUR NORTH AND WE HAVE DECIDED TO NOT ISSUE A FLOOD WATCH AT THIS

TIME. SHOULD THE PRECIP SHIFT SOUTHWARD, WE WOULD BE MORE AT RISK

AND WATCH MAY BE NEEDED. WE WILL CONTINUE TO MONITOR THIS.

THE INCREASED MOISTURE WILL ALSO RAISE DEWPOINTS INTO THE UPPER 60S

TO LOWER 70S FOR WEDNESDAY AND THURSDAY MAKING IT NOT ONLY HOT OUT

BUT QUITE HUMID AS WELL.

WEDNESDAY NIGHT WE SEE YET ANOTHER SHORTWAVE ROTATE AROUND THE MID

LEVEL RIDGE, KEEPING SHOWERS AND THUNDERSTORMS IN THE FORECAST.

Excellent write up as usual from our local NWS office.

As usual, the CWA has a shot @ activity tomorrow. And as usual, it's going to have to be a now cast event. Not expecting too much in the way of severe wx tomorrow, maybe a warning here and there. But as stressed above, slow moving, high PWAT values will cause localized flash flooding. Also, with water logging, localized downburst with collapsing updrafts ( lack of vertical shear to tilt the updrafts) will be the wind threat.

Thursday and friday look a little better with shear profiles and better thermos, as well as a better lifting mechanism. But lets just take it one day at a time.

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There's actually some good veering in the lower levels tomorrow evening. Uni-directional shear is weak, probably 20 mph at best, but it might be enough to sustain storms for at least a little while. The good veering shows up in the hodographs on the NAM. Both images are for 0z Thursday.

18z NAM:

post-1820-0-60740800-1308710767.png

0z NAM:

post-1820-0-82478400-1308710725.png

The 18z NAM had a line of storms rotating NEWD through Philly, whereas the 0z had a N-S squall line from Philly south through the Delmarva moving EWD. The hail potential is very limited, imo, but I think the tornado potential is somewhat there.

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There's actually some good veering in the lower levels tomorrow evening. Uni-directional shear is weak, probably 20 mph at best, but it might be enough to sustain storms for at least a little while. The good veering shows up in the hodographs on the NAM. Both images are for 0z Thursday.

18z NAM:

post-1820-0-60740800-1308710767.png

0z NAM:

post-1820-0-82478400-1308710725.png

The 18z NAM had a line of storms rotating NEWD through Philly, whereas the 0z had a N-S squall line from Philly south through the Delmarva moving EWD. The hail potential is very limited, imo, but I think the tornado potential is somewhat there.

I feel like i've posted more on this thread than there's been comments in the last 2 days :whistle: lol. Thanks for contributing.

NAM_218_2011062200_F21_40.0000N_75.5000W.png

Def a concern for a brief tornado threat around 18z to 0z

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I think we might see a 5% tor from SPC either at 06z or 12z

My guess is we get reintroduced into the SLGT risk, 5% tor, 5% hail, 15% wind

I'd say thats a safe bet. But if the convection out to our west leaves any cloud debris in the morning, it's bound to change.. Gotta love mesodynamics!

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Those storms from Tn Valley might just make it here by 4 am this morning. I am crossing my figures for training thunderstorms. We need the rain.

by the looks of the radar Tennessee can keep their storms, we've got our own showers and storms popping up in York County down through the Delmarva

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Back in the slight risk for tomorrow. 2/15/15.

..CNTRL APPALACHIAN MTNS/MID-ATLANTIC

AN UPPER-LEVEL RIDGE WILL MOVE EWD INTO THE NRN APPALACHIAN MTNS AS

AN UPPER-LEVEL TROUGH APPROACHES THE REGION FROM THE SOUTHWEST. ON

THE WRN EDGE OF THE UPPER-LEVEL RIDGE... AN AXIS OF MODERATE TO

STRONG INSTABILITY IS FORECAST TO DEVELOP FROM WCNTRL PA SSEWD INTO

MD AND ERN VA. THUNDERSTORMS SHOULD INITIATE IN THE HIGHER TERRAIN

OF THE CNTRL APPALACHIAN MTNS AND MOVE EWD ACROSS THE INSTABILITY

AXIS THIS AFTERNOON. FORECAST SOUNDINGS ALONG THIS CORRIDOR AT 21Z

SHOW MLCAPE VALUES IN THE 2000 TO 3000 J/KG RANGE ALONG WITH 40 TO

45 KT OF DEEP LAYER SHEAR. ALTHOUGH THIS SHOULD BE SUFFICIENT FOR

SUPERCELLS AND ISOLATED LARGE HAIL...CONVECTION MAY TEND TO LINE

OUT. THIS WOULD FAVOR WIND DAMAGE AS THE GREATER THREAT THIS

AFTERNOON IN THE MID-ATLANTIC REGION.

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Big area on Day 2 also.

..UPSTATE NY SWWD TO TN

UPPER LOW WILL MIGRATE SLOWLY EWD ACROSS THE GREAT LAKES DURING THE

DAY2 PERIOD WITH THE PRIMARY TROUGH AXIS EXPECTED TO EXTEND SWD

ALONG THE IND/IL BORDER INTO WRN TN BY MID DAY. AHEAD OF THE TROUGH

MODELS CONTINUE TO SUGGEST MODERATE SWLY FLOW ALOFT WILL EXTEND

ACROSS MOST OF THE WARM SECTOR WITH DEEP LAYER SHEAR...SFC-6KM

VALUES ON THE ORDER OF 30-35KT...EXPECTED TO PROVIDE ORGANIZATIONAL

POTENTIAL FOR THE STRONGEST UPDRAFTS.

NEITHER THE NAM OR GFS ARE PARTICULARLY AGGRESSIVE IN DESTABILIZING

THE PRE-FRONTAL AIR MASS AS CURRENTLY DELINEATED BY SLGT RISK.

HOWEVER...BOTH SUGGEST BOUNDARY LAYER LAPSE RATES WILL STEEPEN

RAPIDLY BY 18Z ALONG THE SPINE OF THE APPALACHIANS THUS SUFFICIENT

BUOYANCY SHOULD EXIST FOR ROBUST UPDRAFTS GIVEN THE DEEP LAYER

SHEAR. AT THIS TIME IT APPEARS GUSTY WINDS AND HAIL ARE THE PRIMARY

SEVERE THREATS.

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SPC put us back in a SLGT for tomorrow, 2% tor, 15% wind, 15% hail

they mentioned right in the disco though...

FORECAST SOUNDINGS ALONG THIS CORRIDOR AT 21Z SHOW MLCAPE VALUES IN THE 2000 TO 3000 J/KG RANGE ALONG WITH 40 TO 45 KT OF DEEP LAYER SHEAR. ALTHOUGH THIS SHOULD BE SUFFICIENT FOR SUPERCELLS AND ISOLATED LARGE HAIL...CONVECTION MAY TEND TO LINE OUT. THIS WOULD FAVOR WIND DAMAGE AS THE GREATER THREAT THIS AFTERNOON IN THE MID-ATLANTIC REGION.

I'm not sure I see how this logically follows, since he first mentions shear sufficient for supercells, but then says convection will line out without giving a reason. although i don't think we have enough shear to maintain supercells tomorrow in the first place

note: time-sensitive link, too lazy to save and upload

day1probotlk_1200_torn.gif

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Make that 3 days of Slight Risk now.

DAY 3 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

0216 AM CDT WED JUN 22 2011

VALID 241200Z - 251200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM WY...SEWD ACROSS THE CNTRL

PLAINS INTO THE TN VALLEY...EXTENDING NEWD INTO THE MIDDLE ATLANTIC

AND ERN NY...

...SYNOPSIS...

A MEANDERING ZONE OF POTENTIAL FOR SEVERE THUNDERSTORMS WILL EXTEND

FROM WY...SEWD ACROSS THE CNTRL PLAINS INTO THE TN VALLEY BEFORE

ARCING NEWD INTO SRN NY. THIS ZONE OF POTENTIAL ORGANIZATION IS

ALONG THE SRN FRINGES OF STRONGER FLOW ALOFT WHERE SUFFICIENT

INSTABILITY WILL EXIST FOR DEEP CONVECTION.

...NY INTO THE MIDDLE ATLANTIC...

SLOW MOVING UPPER TROUGH WILL EASE INTO THE ERN GREAT LAKES/OH

VALLEY FRIDAY. LATEST MODEL GUIDANCE SUGGEST MUCH OF THE MIDDLE

ATLANTIC INTO ERN NY WILL DESTABILIZE SUFFICIENTLY FOR ROBUST

THUNDERSTORM ACTIVITY WITHIN FLOW REGIME SEEMINGLY FAVORABLE FOR AT

LEAST ORGANIZED MULTI-CELL UPDRAFTS AND EVEN A FEW SUPERCELLS.

GREATEST SHEAR/BUOYANCY SHOULD BE NOTED ACROSS THE DELMARVA INTO

SERN VA AND THIS MAY BE WHERE MORE CONCENTRATED SEVERE IS ULTIMATELY

OBSERVED.

..DARROW.. 06/22/2011

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I had some nice storms lastnight not a direct hit, but enough of one to get some Lightning filmed from it. Barely any sleep overnight. But it was worth it. Thanks Ryan for the Alert call. But i might have gotten some decent spider lightning. Then this morning i got up earlier then my alarm and saw a cell in NE MD into New Castle De, had been putting some lightning down but died as it got into SE PA, But i did take a nice double rainbow shot that it gave me as a present. Then had some road ponding heavy rains this morning on the way into work.

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Another excellent write up by mt holly:

Near term:

BEHIND THE FRONT DEWPOINTS INCREASE INTO THE MID-70S IN SOME SPOTS

AND WINDS TURN MORE TOWARDS THE SOUTH-SOUTHWEST. AHEAD OF THE FRONT

SKIES SHOULD REMAIN BROKEN TO POSSIBLY OVERCAST WHICH WILL REALLY

DAMPEN ANY CHANCES AT SEVERE CONVECTION. THINKING AT THE MOMENT IS

THAT ACROSS THE SOUTH, PHILADELPHIA SOUTH, WE SHOULD BE ABLE TO

BREAK OUT ENOUGH TODAY TO ALLOW MORE INTENSE HEATING TO TAKE PLACE

COUPLED WITH A LEE-SIDE TROUGH FORMATION AND LOW-LEVEL MOISTURE

CONVERGENCE TO INCREASE OUR CHANCES AT IGNITING DEEP CONVECTION.

PWATS INCREASE ABOVE 2 INCHES LEAVING ANY STORM WITH THE POTENTIAL

TO DROP AN COPIOUS AMOUNT OF RAIN IN A SHORT TIME. BULK SHEAR LOOKS

TO BE RIGHT ON THE CUSP OF SUPER-CELLULAR AT ABOUT 25 KNOTS SO THERE

COULD BE SOME SPINNERS TODAY. TODAYS MAIN THREAT LOOKS TO BE HAIL

AND WET-MICRO BURSTS, BUT AS IT HAS BEEN SAID MANY TIMES TO ME, WITH

SUPERCELLS, ANYTHING GOES (THANKS HAYES!).

DID NOT WANT TO RAISE ANY FLASH FLOOD HEADLINES SINCE CURRENT

THINKING HAS MOST OF THE SEVERE CONVECTION WILL STAY SOUTH OF THE

LOWEST FFG ACROSS OUR NORTHERN ZONES. THE ATMOSPHERE MAY HAVE

TIPPED ITS HAND TO US TONIGHT IN REGARDS TO CONVECTIVE MODE AND

POSITIONING, WHERE THE THETA-E RIDGING SETS UP..ACROSS THE

SOUTHERN HALF OF THE CWA.-- End Changed Discussion --

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MESOSCALE DISCUSSION 1357

NWS STORM PREDICTION CENTER NORMAN OK

0103 PM CDT WED JUN 22 2011

AREAS AFFECTED...ERN PA/MD/VA

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 221803Z - 222000Z

STORMS ARE EXPECTED TO INCREASE IN COVERAGE AND INTENSITY THROUGH

THE AFTERNOON AS DIURNAL DESTABILIZATION OCCURS. CONVECTIVE TRENDS

WILL BE MONITORED FOR A POSSIBLE WW.

STORMS ARE CURRENTLY FORMING OVER THE HIGHER TERRAIN OF PA WITH MORE

DEVELOPMENT EXPECTED FARTHER SOUTH INTO VA LATER THIS AFTERNOON OVER

THE TERRAIN AND INVOF LEE SURFACE TROUGH. WITH SURFACE DEWPOINTS

AROUND 70F...THE ATMOSPHERE WILL BECOME MODERATELY UNSTABLE WITH

MLCAPE VALUES AOA 1000 J/KG. AS THE UPPER LOW SLOWLY APPROACHES

FROM THE WEST...DEEP-LAYER SHEAR WILL REMAIN AROUND 30-35

KTS...WHICH WILL BE SUFFICIENT FOR STORM ORGANIZATION. GIVEN THE

RELATIVELY WEAK LAPSE RATES...THE GREATEST SEVERE THREAT APPEARS TO

BE DAMAGING WINDS...ESPECIALLY AS STORMS MATURE AND COLD POOLS MERGE

IN THE PRESENCE OF FAVORABLE LOW-LEVEL SHEAR /I.E. 0-3 KM SHEAR

AROUND 30 KTS PER AREA VWP DATA/.

..JIRAK.. 06/22/2011

post-1201-0-26200100-1308767350.gif

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BULLETIN - EAS ACTIVATION REQUESTED

SEVERE THUNDERSTORM WARNING

NATIONAL WEATHER SERVICE MOUNT HOLLY NJ

253 PM EDT WED JUN 22 2011

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...

BUCKS COUNTY IN SOUTHEAST PENNSYLVANIA...

MONTGOMERY COUNTY IN SOUTHEAST PENNSYLVANIA...

NORTHERN PHILADELPHIA COUNTY IN SOUTHEAST PENNSYLVANIA...

* UNTIL 400 PM EDT

* AT 251 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A

SEVERE THUNDERSTORM CAPABLE OF PRODUCING QUARTER SIZE HAIL...AND

DAMAGING WINDS IN EXCESS OF 60 MPH. THIS STORM WAS LOCATED NEAR

COLLEGEVILLE...OR 20 MILES NORTHEAST OF WEST CHESTER...AND MOVING

EAST AT 25 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...

LANSDALE...HATFIELD AND SOUDERTON AROUND 310 PM EDT...

FRICKS AROUND 320 PM EDT...

CHALFONT AROUND 325 PM EDT...

DOYLESTOWN AND HATBORO AROUND 335 PM EDT...

IVYLAND AROUND 340 PM EDT...

RICHBORO AROUND 350 PM EDT...

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BULLETIN - EAS ACTIVATION REQUESTED

SEVERE THUNDERSTORM WARNING

NATIONAL WEATHER SERVICE MOUNT HOLLY NJ

307 PM EDT WED JUN 22 2011

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...

SOUTHEASTERN BURLINGTON COUNTY IN SOUTHERN NEW JERSEY...

OCEAN COUNTY IN SOUTHERN NEW JERSEY...

* UNTIL 400 PM EDT

* AT 303 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A

SEVERE THUNDERSTORM CAPABLE OF PRODUCING QUARTER SIZE HAIL...AND

DAMAGING WINDS IN EXCESS OF 60 MPH. THIS STORM WAS LOCATED NEAR

BATSTO...OR 24 MILES NORTHEAST OF VINELAND...AND MOVING NORTHEAST

AT 20 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...

8 MILES NORTHWEST OF WADING RIVER AROUND 315 PM EDT...

PENN STATE FOREST AROUND 335 PM EDT...

CHATSWORTH AROUND 340 PM EDT...

6 MILES NORTHWEST OF WARREN GROVE AROUND 350 PM EDT...

OLD HALFWAY AROUND 355 PM EDT...

BAMBER LAKE...6 MILES NORTHWEST OF BROOKVILLE...8 MILES SOUTH OF

CEDAR GLEN LAKES AND 8 MILES SOUTH OF WHITING AROUND 400 PM EDT...

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