Alert archive / Pennsylvania / Mesoscale Discussions in 2004
Mesoscale Discussion 1663
The Storm Prediction Center issued this mesoscale discussion at Jul 14, 2004, 12:06 PM EDT for 41 counties in Pennsylvania. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Jul 14, 2004, 12:06 PM EDT (16:06 UTC)
- Expired
- Jul 14, 2004, 2:30 PM EDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
All 41 counties
Adams County, PA, Allegheny County, PA, Armstrong County, PA, Bedford County, PA, Blair County, PA, Butler County, PA, Cambria County, PA, Cameron County, PA, Centre County, PA, Clarion County, PA, Clearfield County, PA, Clinton County, PA, Columbia County, PA, Cumberland County, PA, Dauphin County, PA, Elk County, PA, Forest County, PA, Franklin County, PA, Fulton County, PA, Huntingdon County, PA, Indiana County, PA, Jefferson County, PA, Juniata County, PA, Lancaster County, PA, Lawrence County, PA, Lebanon County, PA, Lycoming County, PA, McKean County, PA, Mifflin County, PA, Montour County, PA, Northumberland County, PA, Perry County, PA, Potter County, PA, Schuylkill County, PA, Snyder County, PA, Somerset County, PA, Tioga County, PA, Union County, PA, Venango County, PA, Westmoreland County, PA, York County, PA
The radar
The State College radar (KCCX), 41 km from the middle of the area, began a volume at 16:05 UTC, the scan nearest the moment this went out.
Open the radar archive at this moment
The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.
The watches that followed
Watches SPC issued over any of the same counties within four hours of this discussion.
The nearest sounding before it
Pittsburgh, PA (KPIT), launched 12:00Z, 4.1 hours before the alert went out and 146 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 940 J/kg
- Mixed-layer CIN
- -69 J/kg
- Mixed-layer LCL
- 792 m above ground
- 0-6 km bulk shear
- 27 kt
- 0-1 km storm-relative helicity
- 49 m²/s²
- 0-3 km storm-relative helicity
- 73 m²/s²
- Significant tornado parameter
- 0.2
- Supercell composite
- 0.9
The text
As transmitted, in the capitals the NWS used until 2016.
790 ACUS11 KWNS 141606 SWOMCD SPC MCD 141606 PAZ000-MDZ000-141830- MESOSCALE DISCUSSION 1663 NWS STORM PREDICTION CENTER NORMAN OK 1106 AM CDT WED JUL 14 2004 AREAS AFFECTED...CNTRL PA CONCERNING...SEVERE THUNDERSTORM POTENTIAL VALID 141606Z - 141830Z ISOLD TO WIDELY SCATTERED SEVERE STORMS MAY DEVELOP ACROSS PARTS OF CNTRL/WRN PA OVER THE NEXT 1-3 HOURS. OVERALL ORGANIZED STORM COVERAGE IS UNCERTAIN AT THIS POINT BASED ON SOMEWHAT MARGINAL SHEAR. HOWEVER...A WATCH MAY BE NEEDED OVER PARTS OF THE AREA. NARROW WARM SECTOR WAS DEVELOPING ACROSS PORTIONS OF CNTRL PA WITH LATEST MLCAPE ESTIMATED AROUND 1000 J/KG. MEANWHILE...UPPER TROUGH AND ASSOCIATED COLD FRONT WERE MAKING STEADY EWD PROGRESS ACROSS WRN PA WITH A TRAILING WIND SHIFT/CONVERGENCE AXIS EXTENDING FROM NERN OH INTO NWRN PA. TSTMS HAVE BEEN DEVELOPING ALONG THE POST FRONTAL WIND SHIFT LINE ACROSS NWRN PA OVER THE PAST COUPLE OF HOURS WITH VIL/REFLECTIVITY VALUES SLOWLY INCREASING. GIVEN MOIST AIRMASS AND MODEST INSTABILITY IN THE PRESENCE OF STRONG LARGE SCALE FORCING AND SOMEWHAT MARGINAL DEEP LAYER SHEAR OF 25-30KT...SITUATION APPEARS SUPPORTIVE OF A FEW SUPERCELLS OR ORGANIZED MULTICELL STORMS. THIS POTENTIAL SHOULD CONTINUE TO INCREASE INTO THE AFTERNOON WITH A FEW HAIL AND/OR WIND REPORTS POSSIBLE. STORMS DEVELOPING EWD AND CROSSING THE WARM FRONT MAY ENCOUNTER MORE ENHANCED LOW LEVEL SHEAR AND ACQUIRE SUPERCELL CHARACTERISTICS. IF WIDESPREAD SEVERE WEATHER POTENTIAL BECOMES MORE CERTAIN...A WATCH WOULD BE NEEDED. ..CARBIN.. 07/14/2004 ...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT... ATTN...WFO...PHI...BGM...CTP...LWX...PBZ... 39757928 40187976 40508022 40918050 41557969 41787925 41907880 41977830 41847729 41407647 40507607 39887617 39747700 39717841
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 14, 1:15 PM EDT | Severe Thunderstorm Watch | SPC | Adams, Bedford, Berks, Blair, Carbon, Centre and 27 more | 6 hr |
| Jul 14, 3:16 PM EDT | Mesoscale Discussion | SPC | Susquehanna, Wayne, Wyoming | 89 min |
| Jul 14, 3:40 PM EDT | Mesoscale Discussion | SPC | Adams, Bedford, Berks, Blair, Carbon, Centre and 28 more | 95 min |
Nearby
Mesoscale Discussions in Pennsylvania, 2004Every mesoscale discussion in 2004
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.