Alert archive / Maine / Tornado Watches in 2002

Tornado Watch 490

July 4, 200216 counties in Maine; 7 counties in New Hampshire

The Storm Prediction Center issued this tornado watch at Jul 4, 2002, 12:00 PM EDT for 16 counties in Maine; 7 counties in New Hampshire. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued: Jul 4, 2002, 12:00 PM EDT (16:00 UTC)
Expired: Jul 4, 2002, 6:00 PM EDT
In force: 6 hr
Issued by: the Storm Prediction Center

All 23 counties

Androscoggin County, ME, Aroostook County, ME, Cumberland County, ME, Franklin County, ME, Hancock County, ME, Kennebec County, ME, Knox County, ME, Lincoln County, ME, Oxford County, ME, Penobscot County, ME, Piscataquis County, ME, Sagadahoc County, ME, Somerset County, ME, Waldo County, ME, Washington County, ME, York County, ME, Belknap County, NH, Carroll County, NH, Coos County, NH, Grafton County, NH, Merrimack County, NH, Strafford County, NH, Sullivan County, NH

The radar

The Portland,ME radar (KGYX), 113 km from the middle of the area, began a volume at 16:01 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.

Warnings issued inside it

10 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

Issued	Product	Office	Counties	Lasted
Jul 4, 12:10 PM EDT	Tornado Warning	CAR	Aroostook	50 min
Jul 4, 12:38 PM EDT	Tornado Warning	CAR	Aroostook	22 min
Jul 4, 12:58 PM EDT	Severe Thunderstorm Warning	CAR	Aroostook	32 min
Jul 4, 1:32 PM EDT	Severe Thunderstorm Warning	CAR	Aroostook	58 min
Jul 4, 3:18 PM EDT	Severe Thunderstorm Warning	CAR	Aroostook, Piscataquis	57 min
Jul 4, 3:38 PM EDT	Tornado Warning	CAR	Aroostook	52 min
Jul 4, 4:30 PM EDT	Severe Thunderstorm Warning	CAR	Aroostook	45 min
Jul 4, 5:03 PM EDT	Severe Thunderstorm Warning	GYX	Somerset	27 min
Jul 4, 5:13 PM EDT	Severe Thunderstorm Warning	CAR	Penobscot	47 min
Jul 4, 5:32 PM EDT	Severe Thunderstorm Warning	CAR	Washington	43 min

The nearest sounding before it

Gray, ME (KGYX), launched 12:00Z, 4.0 hours before the alert went out and 113 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.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 2495 J/kg
Mixed-layer CIN: -69 J/kg
Mixed-layer LCL: 1276 m above ground
0-6 km bulk shear: 26 kt
0-1 km storm-relative helicity: 8 m²/s²
0-3 km storm-relative helicity: 37 m²/s²
Significant tornado parameter: 0.3
Supercell composite: 2.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

000 
WWUS20 KWNS 041603
SEL0  
SPC WW 041556
MEZ000-NHZ000-042200-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 490
STORM PREDICTION CENTER NORMAN OK
1156 AM EDT THU JUL 4 2002

THE STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF

   MAINE                              
   CENTRAL AND NORTHERN NEW HAMPSHIRE                      

EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM NOON EDT UNTIL
600 PM EDT.

TORNADOES...HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS
TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE TORNADO WATCH AREA IS ALONG AND 100 STATUTE MILES EAST AND WEST
OF A LINE FROM 35 MILES SOUTH SOUTHWEST OF PORTLAND MAINE TO 40
MILES NORTH OF CARIBOU MAINE.

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH AREA. 
PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR THREATENING
WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE
WARNINGS.

DISCUSSION...THUNDERSTORMS EXPECTED TO DEVELOP UPSTREAM ACROSS
PARTS OF UPSTATE NY/VT AND QUEBEC SHOULD SPREAD E ACROSS WW THIS
AFTERNOON...WHERE AMPLE SHEAR/INSTABILITY WILL BE PRESENT FOR
SUPERCELLS.  MAIN SEVERE THREATS WILL BE LARGE HAIL AND HIGH WINDS
WITH BOWING STORMS.  BUT WEAK LOW LEVEL CONVERGENCE FIELD /WHICH
MAY DELAY ASSUMPTION OF A LINEAR STORM MODE/...HIGH SURFACE
DEWPOINTS AND SOMEWHAT BACKED FLOW OVER ERN ME SUGGEST AN
ADDITIONAL THREAT FOR TORNADOES. 

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 2 INCHES.  EXTREME TURBULENCE AND SURFACE WIND
GUSTS TO 60 KNOTS.  A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550. 
MEAN STORM MOTION VECTOR 29035.

...CORFIDI

430,0723 472,0700 472,0655 430,0683

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 4, 6:00 PM EDT	Severe Thunderstorm Watch	SPC	Androscoggin, Cumberland, Hancock, Kennebec, Lincoln, Oxford and 5 more	6 hr

Nearby

Tornado Watches in Maine, 2002 Tornado Watches in New Hampshire, 2002 Every tornado watch in 2002

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.