Alert archive / New Hampshire / Flash Flood Warnings in 2021

Flash Flood Warning 2, NWS Gray, ME

June 8, 2021Hillsborough County, New Hampshire

NWS Gray, ME issued this flash flood warning at Jun 8, 2021, 3:30 PM EDT for Hillsborough County, New Hampshire. It was in force for 2 hr. 2 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Jun 8, 2021, 3:30 PM EDT (19:30 UTC)
Expired: Jun 8, 2021, 5:50 PM EDT
In force: 2 hr
Issued by: NWS Gray, ME
Area: Storm-based polygon
Flood severity: None

County Hillsborough County, NH

The radar

The Boston radar (KBOX), 92 km from the middle of the area, began a volume at 19:31 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.

What was reported inside it

Time	Report	Where	Remark
Jun 8, 4:00 PM EDT	FLASH FLOOD	1 Sse Nashua, NH	APPROX TIME. TWITTER REPORT PLUS CALLED LOCAL BUSINESS TO VERIFY SEVERAL INCHES OF WATER OVER NORTHEASTERN BLVD AT MURPHY DRIVE. HAS SINCE CLEARED UP.
Jun 8, 4:28 PM EDT	HEAVY RAIN 1.2	1 Ese Nashua, NH	AS OF 4:25 PM. BULK OF AMOUNT FELL IN 30 MINUTES BETWEEN 3:15 AND 3:45.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Gray, ME (KGYX), launched 12:00Z, 7.5 hours before the alert went out and 157 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: 36 J/kg
Mixed-layer CIN: -174 J/kg
Mixed-layer LCL: 1529 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: 20 m²/s²
0-3 km storm-relative helicity: 33 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

979 
WGUS51 KGYX 081930
FFWGYX
NHC011-090030-
/O.NEW.KGYX.FF.W.0002.210608T1930Z-210609T0030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Gray ME
330 PM EDT Tue Jun 8 2021

The National Weather Service in Gray has issued a

* Flash Flood Warning for...
  Southeastern Hillsborough County in southern New Hampshire...

* Until 830 PM EDT.

* At 330 PM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 2 inches of rain 
  have fallen. Additional rainfall amounts of 1 to 2.5 inches are 
  possible in the warned area. Flash flooding is ongoing or expected 
  to begin shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar and automated gauges.

  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...
  Nashua, Merrimack, Salem, Milford, Amherst, Litchfield, Hollis, 
  Hudson, and Pelham.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Be aware of your surroundings and do not drive on flooded roads.

&&

LAT...LON 4271 7167 4282 7165 4279 7137 4278 7136
      4278 7135 4277 7135 4276 7126 4274 7125
      4270 7129

FLASH FLOOD...RADAR INDICATED

$$

MEC

1 follow-up statement

416 
WGUS71 KGYX 082150
FFSGYX

Flash Flood Statement
National Weather Service Gray ME
550 PM EDT Tue Jun 8 2021

NHC011-082200-
/O.CAN.KGYX.FF.W.0002.000000T0000Z-210609T0030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Hillsborough NH-
550 PM EDT Tue Jun 8 2021

...FLASH FLOOD WARNING FOR SOUTHEASTERN HILLSBOROUGH COUNTY HAS BEEN 
REPLACED WITH A FLOOD ADVISORY...

Heavy rain has moved out of the area but additional light to 
occasionally moderate rainfall is expected through the evening.

LAT...LON 4271 7167 4282 7165 4279 7137 4278 7136
      4278 7135 4277 7135 4276 7126 4274 7125
      4270 7129

$$

Tubbs

The office that day

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

Issued	Product	Office	Counties	Lasted
Jun 8, 3:14 PM EDT	Flash Flood Warning	GYX	Cheshire, Hillsborough	2 hr
Jun 8, 3:24 PM EDT	Flash Flood Watch	GYX	Cheshire, Hillsborough	6 hr
Jun 8, 3:53 PM EDT	Flash Flood Warning	GYX	Cheshire	5 hr
Jun 8, 4:52 PM EDT	Special Weather Statement	GYX	Strafford	38 min
Jun 8, 4:53 PM EDT	Special Weather Statement	GYX	Cheshire	37 min
Jun 8, 4:56 PM EDT	Special Weather Statement	GYX	Merrimack	34 min
Jun 8, 5:15 PM EDT	Special Weather Statement	GYX	Cheshire	45 min
Jun 8, 5:50 PM EDT	Areal Flood Advisory	GYX	Hillsborough	3 hr
Jun 8, 6:24 PM EDT	Areal Flood Advisory	GYX	Merrimack, Rockingham, Strafford	115 min

Nearby

Flash Flood Warnings in New Hampshire, 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.