| SPC Severe Weather Event has been posted at SPC for this storm. The 15Z HPC surface analysis shows a warm front pushing over the Delmarva peninsula into PA and NJ. We will be in the warm sector by midafternoon. SPC Mesoscale Discussion #330 is reproduced below. |  |
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| MESOSCALE DISCUSSION 0330 NWS STORM PREDICTION CENTER NORMAN OK 0453 PM CDT SUN MAR 29 2009 AREAS AFFECTED...EXTREME ERN PA...WRN NJ...NRN DE AND EXTREME NERN MD CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY VALID 292153Z - 292330Z  |
SVR THREAT WILL EXIST ACROSS EXTREME ERN PA...NJ...NRN DE AND NERN MD FOR A FEW MORE HOURS. DMGG WIND GUSTS AND LARGE HAIL ARE LIKELY...BUT A TORNADO RISK CANNOT BE RULED OUT SOUTH OF A LINE FROM KPTW-KDYL SWD TO INCLUDE ALL OF THE PHL METRO AREA. BKN LINE OF TSTMS...INCLUDING SUPERCELLS...CONTINUES TO ORGANIZE FROM AVOCA SWD TO BALTIMORE. INTENSE CELL THAT PRODUCED SVR WIND GUSTS IN READING HAS MOVED N OF THE WRMFNT BUT WILL AFFECT KABE-KUKT REGION NEWD INTO NRN NJ AND PERHAPS WRN LONG ISLAND WITH A LARGE HAIL THREAT FOR A FEW MORE HOURS. FARTHER S...THERE SEEMS TO BE AN INCREASING THREAT FOR SUPERCELLS AND TORNADOES INVOF THE WRMFNT/SFC LOW ACROSS THE PHL METRO AREA WHERE 2-HRLY PRESSURE FALLS WERE IN EXCESS OF 3 MB. HERE...STORMS DEVELOPING OVER CHESTER COUNTY SWD INTO NERN MD WILL LIKELY MOVE ENE WITHIN THE CAPE AXIS TOWARD PHL. THESE STORMS WILL HAVE AVAILABILITY TO THE STRONGEST STORM RELATIVE HELICITY AND POTENTIAL FOR TORNADOES AS THEY CROSS THE WRMFNT. AFTER COORDINATION WITH THE MOUNT HOLLY OFFICE...A SVR WEATHER WATCH WILL NOT BE ISSUED. HOWEVER...THERE WILL NEED TO BE A HEIGHTENED AWARENESS FOR THE POTENTIAL FOR SVR WEATHER...INCLUDING TORNADOES IN THE PHL METRO AREA FROM 2230-00Z. AT LEAST ISOLD LARGE HAIL/DMGG WIND THREATS WILL EXTEND ENE INTO MUCH OF NJ THROUGH MID-EVENING. |
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| 2245Z (1845 EDT) Last KDIX report prior to 1 hour period with no data. Cells are still relatively discrete, but radial velocity data is unremarkable. The storms are moving quickly, so we pack up and get ready to go. |  |
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| 2311Z (1911EDT) Looking SW. CB tops are visible above low clouds preceding squall line. No radar data is available, and the sun is too low for satellite imagery to be revealing. Stay put and watch. |  |
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| 2323Z (1923 EDT) Shelf cloud is clearly visible, with nice sculpted effect. At present, conclude that we are out of position if this is a supercell--watching the forward flank of the approaching storm |  |
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| 2323Z Panoramic view of multi-tiered shelf cloud. View is approximately 90-100 degrees. |  |
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| 2324Z (1924 EDT) The speed of this storm is evident in the changes that have occurred in the minute since the last panoramic sequence was shot. |  |
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| 2324Z panoramic view |  |
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| 2326Z (1926 EDT) Lasy shot before packing up. The winds have shifted to the west as the gust front has reached us. Thunder is audible and lightning dimly visible in the gloom beneath the cloud base. |  |
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| 19:28:14 EDT. Just prior to rolling up window and heading out. No tripod--steady camera agains window and hope for the best in this ~1 sec exposure. |  |
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| 19:28:54 EDT. Can't resist one more shot. We head east looking to get ahead of the storm and pick up the rear flank if possible. At this point, however, there is little reason to expect we will be able to reach it: daylight is fading and it looks like a linear structure as far as the eye can see. |  |
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| Rain begins as we hit the road, and we remain in rain for the next 20 minutes. We catch sight of a wall cloud in the distance and spot a definite (if unimposing) inflow band but the treeline prevents getting good pictures. At right: video stills of the wall cloud, shot from the moving car by Spencer. |  |
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| By the time we reach Allentown, visibility is about 50 yards in very heavy rain and hail. |  |
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| By 2354Z, we are out of the hail and heavy rain and heading home. This is the first useful radar data from KDIX since 2245Z. |  |