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June 2012 Severe Weather/Convection Discussion


earthlight

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It seems as if we do not generally receive severe storms when we are coming out of a heat wave. Instead, we fare way better when the temperatures are in the 80s or 70s. Also, whenever the area is expecting more than a half-inch of rain during the expected "severe" weather day, it dooms our chances of getting organized severe storms. The heavy rain probably creates too much convective debris in the afternoon with those unimpressive cirrostratus clouds instead of explosive cumulus clouds.

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The steep low level lapse rates should help out for the severe wind gust potential in the strongest cells today.

Another threat is going to be flash flooding with PW's topping 1.8 inches under the areas of strongest convection.

We may also see a very high total of lightning strikes per hour under this type of set up.

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The steep low level lapse rates should help out for the severe wind gust potential in the strongest cells today.

Another threat is going to be flash flooding with PW's topping 1.8 inches under the areas of strongest convection.

We may also see a very high total of lightning strikes per hour under this type of set up.

About what time this afternoon should we expect storms to be in and about the NYC area? Is this an early afternoon or evening thing?

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About what time this afternoon should we expect storms to be in and about the NYC area? Is this an early afternoon or evening thing?

The cap is weak. Convection could get on by early this afternoon and become widespread into this evening. With low shear, high PWATS and low mid-level instability, I think main threats are torrential rains and some wet microbursts.

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The cap is weak. Convection could get on by early this afternoon and become widespread into this evening. With low shear, high PWATS and low mid-level instability, I think main threats are torrential rains and some wet microbursts.

You're thinking slow moving storms then?

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The cap is weak. Convection could get on by early this afternoon and become widespread into this evening. With low shear, high PWATS and low mid-level instability, I think main threats are torrential rains and some wet microbursts.

Winds are a legit threat.

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35k+ effective bulk shear is moving into the area, SBCAPE is already surging over 1500 J/KG, mid-level lapse rates are improving and low level lapse rates are high. Overall I think a fairly good setup for us.

Skies have cleared here in Ramsey and we have hazy sunshine. Not a single cloud in the sky.

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You would usually want these clouds out of the way to get some sun before the weak forcing arrives..but we're plenty unstable and especially with such a weak cap, we should be ok.

http://www.meteo.psu.edu/~gadomski/SAT_PA/anim8vis.html

The SPC WRF didn't have the storms getting going until 20z and impacting the area until 21-22z anyway, so we still have plenty of time.

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You would usually want these clouds out of the way to get some sun before the weak forcing arrives..but we're plenty unstable and especially with such a weak cap, we should be ok.

http://www.meteo.psu.edu/~gadomski/SAT_PA/anim8vis.html

The SPC WRF didn't have the storms getting going until 20z and impacting the area until 21-22z anyway, so we still have plenty of time.

Sun is out and has been for a while for many espeixally nj and ct where threat is greatest.

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You would usually want these clouds out of the way to get some sun before the weak forcing arrives..but we're plenty unstable and especially with such a weak cap, we should be ok.

http://www.meteo.psu...A/anim8vis.html

The SPC WRF didn't have the storms getting going until 20z and impacting the area until 21-22z anyway, so we still have plenty of time.

The 12Z HRRR has coverage in NE PA really exploding the next 2 hours or so.

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You would usually want these clouds out of the way to get some sun before the weak forcing arrives..but we're plenty unstable and especially with such a weak cap, we should be ok.

http://www.meteo.psu...A/anim8vis.html

The SPC WRF didn't have the storms getting going until 20z and impacting the area until 21-22z anyway, so we still have plenty of time.

youre not thinking anything earlier than that? im thinking pre-frontal stuff where those clouds are at..already a few shwsr have popped up along it...and agree with the weak forcing doing the job, we already saw a t-storm pop up along the jersey shore from a sea breeze.

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mcd1239.gif

MESOSCALE DISCUSSION 1239

NWS STORM PREDICTION CENTER NORMAN OK

1118 AM CDT FRI JUN 22 2012

AREAS AFFECTED...PORTIONS NRN/ERN VA...CENTRAL/ERN PA...SWRN NEW

ENGLAND...SRN NY...DE...MD...NJ...DC.

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 221618Z - 221845Z

PROBABILITY OF WATCH ISSUANCE...60 PERCENT

SUMMARY...SVR THREAT FCST TO INCREASE FROM MULTICELLULAR

CONVECTION...OF DISCRETE...CLUSTERED AND QUASI-LINEAR

CHARACTER...DEVELOPING THROUGH MID-AFTERNOON AND MOVING OVER THIS

AREA. MAIN CONCERN IS DAMAGING GUSTS.

DISCUSSION...TSTMS ARE FCST TO DEVELOP IN AT LEAST TWO PRIMARY

SWATHS OR BANDS...

1. NEAR AND E OF DIFFERENTIAL HEATING ZONE...ASSOCIATED WITH

LOW-MIDDLE LEVEL CLOUD BAND NOW EVIDENT ON VIS IMAGERY FROM ERN PA

SWWD ACROSS VA/WV BORDER REGION. ANY SUCH TSTMS WILL POSE EARLIEST

SVR RISK FROM TIDEWATER AREA NEWD OVER COASTAL MID-ATLC AND SRN NEW

ENGLAND.

2. ALONG/AHEAD OF SFC COLD FRONT...INITIALLY OVER HIGHER TERRAIN OF

CENTRAL PA INTO NRN WV. FRONT PRECEDES POSITIVELY TILTED MID-UPPER

TROUGH BY ABOUT 100-150 NM USING MOISTURE CHANNEL IMAGERY...BUT WITH

SOME LARGE-SCALE ASCENT EVIDENT OVER FRONTAL ZONE. THESE FEATURES

WILL SHIFT EWD OVER MID-ATLC REGION THIS AFTERNOON.

16Z SFC ANALYSIS SHOWED COLD FRONT FROM NRN NY SWWD ACROSS

CENTRAL/SWRN PA AND WRN WV. SFC TROUGH WITH WEAK EMBEDDED LOWS WAS

EVIDENT PARALLEL TO COLD FRONT AND FARTHER E...EXTENDING FROM SERN

VA NNEWD OVER SRN CHESAPEAKE BAY AND ERN NJ TO RI AND ERN

MA...INTERSECTING WARM FRONT JUST OFFSHORE NH. WARM FRONT EXTENDED

NNEWD FROM THERE OVER MAINE. TROUGH APPEARS COLLOCATED WITH SEA

BREEZE BOUNDARY OVER ERN NJ...AND A COUPLE OF TSTMS ALREADY HAVE

DEVELOPED THERE.

MODIFIED IAD/APG/WAL/OKX RAOBS SUGGEST PREFRONTAL BOUNDARY LAYER

SHOULD MIX VIGOROUSLY ACROSS MUCH OF NEAR-COASTAL CORRIDOR IN

RESPONSE TO CONTINUED STG SFC DIABATIC HEATING. SIMILAR PROCESS

SHOULD OCCUR BEHIND AFOREMENTIONED PREFRONTAL CLOUD BAND. RESULT

WOULD BE POCKETS OF REDUCED SFC DEW POINTS...AT BASE OF INVERTED-V

THERMODYNAMIC PROFILE FEATURING NEARLY DRY-ADIABATIC LOW-LEVEL LAPSE

RATES. YET MOISTURE WILL REMAIN SUFFICIENT EVEN IN THOSE RELATIVELY

DRY AREAS TO OFFSET MODEST MIDLEVEL LAPSE RATES AND KEEP AT LEAST

MRGL BUOYANCY OVER REGION. GIVEN HORIZONTALLY INHOMOGENEOUS NATURE

OF EXPECTED MIXING/MOISTURE FIELDS...MLCAPE WILL VARY GREATLY WITH

VALUES RANGING FROM 500-2500 J/KG...TRENDING INVERSELY WITH STRENGTH

OF VERTICAL MIXING. 30-35 KT EFFECTIVE SHEAR MAGNITUDES SUPPORT

SOME ORGANIZATION TO MULTICELL MODES...AND POTENTIAL FOR SMALL BOWS

WITH LOCALLY ENHANCED COLD-POOL FORCING.

..EDWARDS/WEISS.. 06/22/2012

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Might be some re-generation going on near the Delaware River...it looks like some of those updrafts might get going again. The boundary near the GSP is dominating right now though, beautiful outflow on the high-resolution KDIX radar from the storm near Toms River.

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I'd definitely watch that batch carefully, just west of Flemington. If some new updrafts can get going just east of the light rain over Allentown, they could hold together and progress eastward towards Northeast NJ and NYC. 30-40kts of 0-6km/effective bulk shear in place.

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I'd definitely watch that batch carefully, just west of Flemington. If some new updrafts can get going just east of the light rain over Allentown, they could hold together and progress eastward towards Northeast NJ and NYC. 30-40kts of 0-6km/effective bulk shear in place.

Where?

shr6.gif

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I was gonna say, lol. You got my hopes up for a minute! :P

Mine were too -- the SREF mean had been lagging the best shear behind the forcing for a few days, so I was surprised to see that earlier this morning. But it seems to have come back down to earth a bit now.

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