Alert archive / New Hampshire / Flash Flood Warnings in 2021

Flash Flood Warning 4, NWS Gray, ME

July 9, 20214 counties in New Hampshire; York County, Maine

NWS Gray, ME issued this flash flood warning at Jul 9, 2021, 1:01 PM EDT for 4 counties in New Hampshire; York County, Maine. It was in force for 4 hr. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Jul 9, 2021, 1:01 PM EDT (17:01 UTC)
Expired: Jul 9, 2021, 5:02 PM EDT
In force: 4 hr
Issued by: NWS Gray, ME
Area: Storm-based polygon
Flood severity: None

Counties York County, ME, Hillsborough County, NH, Merrimack County, NH, Rockingham County, NH, Strafford County, NH

The radar

The Boston radar (KBOX), 102 km from the middle of the area, began a volume at 17:00 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 nearest sounding before it

Gray, ME (KGYX), launched 12:00Z, 5.0 hours before the alert went out and 130 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 638 m above ground
0-6 km bulk shear: 32 kt
0-1 km storm-relative helicity: 101 m²/s²
0-3 km storm-relative helicity: 384 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.2

Open this sounding in Storm Lab

The text

As transmitted.

356 
WGUS51 KGYX 091701
FFWGYX
MEC031-NHC011-013-015-017-100100-
/O.NEW.KGYX.FF.W.0004.210709T1701Z-210710T0100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Gray ME
101 PM EDT Fri Jul 9 2021

The National Weather Service in Gray has issued a

* Flash Flood Warning for...
  Southwestern York County in southwestern Maine...
  Southeastern Merrimack County in central New Hampshire...
  Southern Strafford County in central New Hampshire...
  Eastern Hillsborough County in southern New Hampshire...
  Rockingham County in southern New Hampshire...

* Until 900 PM EDT Friday.

* At 101 PM EDT, Doppler radar indicated heavy rain across the 
  warned area. Between 1 and 2 inches of rain have fallen. 
  Additional rainfall amounts of 1 to 2 inches are possible in the 
  warned area. Flash flooding is expected to begin shortly.

  HAZARD...Flash flooding caused by heavy rain.

  SOURCE...Radar.

  IMPACT...Flash flooding of small creeks and streams, urban
           areas, highways, streets and underpasses as well as
           other poor drainage and low-lying areas.

* Some locations that will experience flash flooding include...
  Manchester, Nashua, Concord, Derry, Rochester, Merrimack, 
  Portsmouth, Hampton, Durham, and Exeter.

This includes the following Rec locations...
	Hampton BeachYork Beach.

This includes the following highways...
	Interstate 95 in New Hampshire between mile markers 0 and 16.
	Interstate 93 between mile markers 1 and 42.
	Interstate 89 between mile markers 0 and 12.
	Interstate 95 between mile markers 1 and 14.
	Interstate 293 between mile markers 1 and 11.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

Flooding is occurring or is imminent. It is important to know where 
you are relative to streams, rivers, or creeks which can become 
killers in heavy rains. Campers and hikers should avoid streams or 
creeks.

&&

LAT...LON 4272 7175 4327 7173 4325 7057 4313 7056
      4298 7070 4286 7076 4283 7079 4283 7081
      4288 7082 4287 7082 4286 7085 4289 7092
      4286 7103 4281 7107 4282 7113 4281 7117
      4279 7119 4274 7118 4274 7125 4270 7129

FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL...2-3 INCHES IN 1 HOUR

$$

SJ

2 follow-up statements

904 
WGUS71 KGYX 092001
FFSGYX

Flash Flood Statement
National Weather Service Gray ME
401 PM EDT Fri Jul 9 2021

MEC031-NHC011-013-015-017-100100-
/O.CON.KGYX.FF.W.0004.000000T0000Z-210710T0100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
York ME-Hillsborough NH-Merrimack NH-Rockingham NH-Strafford NH-
401 PM EDT Fri Jul 9 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 9 PM EDT THIS EVENING 
FOR SOUTHWESTERN YORK, SOUTHEASTERN MERRIMACK, SOUTHERN STRAFFORD, 
EASTERN HILLSBOROUGH, AND ROCKINGHAM COUNTIES...

At 401 PM EDT, Rain is beginning to diminish across the warning 
area. Runoff from earlier showers will continue to cause small 
streams and creeks to rise with ongoing flooding into the evening 
hours.

HAZARD...Flash flooding caused by heavy rain.

SOURCE...Radar.

IMPACT...Flash flooding of small creeks and streams, urban areas,
         highways, streets and underpasses as well as other poor
         drainage and low-lying areas.

Some locations that will experience flash flooding include...
  Manchester, Nashua, Concord, Derry, Rochester, Merrimack, 
  Portsmouth, Hampton, Durham, and Exeter.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.



&&

LAT...LON 4272 7175 4327 7173 4325 7057 4313 7056
      4298 7070 4286 7076 4283 7079 4283 7081
      4288 7082 4287 7082 4286 7085 4289 7092
      4286 7103 4281 7107 4282 7113 4281 7117
      4279 7119 4274 7118 4274 7125 4270 7129

FLASH FLOOD...RADAR INDICATED

$$

SJ

743 
WGUS71 KGYX 092102
FFSGYX

Flash Flood Statement
National Weather Service Gray ME
502 PM EDT Fri Jul 9 2021

MEC031-NHC011-013-015-017-092112-
/O.CAN.KGYX.FF.W.0004.000000T0000Z-210710T0100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
York ME-Hillsborough NH-Merrimack NH-Rockingham NH-Strafford NH-
502 PM EDT Fri Jul 9 2021

...FLASH FLOOD WARNING IS CANCELLED FOR SOUTHWESTERN YORK, 
SOUTHEASTERN MERRIMACK, SOUTHERN STRAFFORD, EASTERN HILLSBOROUGH, 
AND ROCKINGHAM COUNTIES...

The heavy rain has ended. No additional flooding is expected to pose 
a threat. Please continue to heed remaining road closures.



LAT...LON 4272 7175 4327 7173 4325 7057 4313 7056
      4298 7070 4286 7076 4283 7079 4283 7081
      4288 7082 4287 7082 4286 7085 4289 7092
      4286 7103 4281 7107 4282 7113 4281 7117
      4279 7119 4274 7118 4274 7125 4270 7129

$$

SJ

The office that day

Everything else NWS Gray, ME issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 9, 1:10 PM EDT	Flash Flood Warning	GYX	Strafford	4 hr
Jul 9, 3:15 PM EDT	Areal Flood Advisory	GYX	Carroll, Coos, Strafford	3 hr
Jul 9, 3:36 AM EDT	Small Craft Advisory	GYX		35 hr
Jul 9, 6:27 PM EDT	Areal Flood Advisory	GYX	Cumberland, Kennebec, Knox, Lincoln, Sagadahoc, Somerset and 1 more	3 hr

Nearby

Flash Flood Warnings in New Hampshire, 2021 Flash Flood Warnings in Maine, 2021 Every flash flood warning in 2021

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.