Alert archive / Alaska / Severe Thunderstorm Warnings in 2015

Severe Thunderstorm Warning 2, NWS Anchorage, AK

August 18, 2015

NWS Anchorage, AK issued this severe thunderstorm warning at Aug 18, 2015, 5:14 PM AKDT. It was in force for 46 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Aug 18, 2015, 5:14 PM AKDT (01:14 UTC)
Expired: Aug 18, 2015, 6:00 PM AKDT
In force: 46 min
Issued by: NWS Anchorage, AK
Area: Storm-based polygon

The radar

The Kenai radar (PAHG), 86 km from the middle of the area, began a volume at 01:14 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

Anchorage Iap/Pt. Campbe, (PANC), launched 00:00Z, 1.2 hours before the alert went out and 23 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: 87 J/kg
Mixed-layer CIN: -48 J/kg
Mixed-layer LCL: 1530 m above ground
0-6 km bulk shear: 16 kt
0-1 km storm-relative helicity: 39 m²/s²
0-3 km storm-relative helicity: 104 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.3

Open this sounding in Storm Lab

The text

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

887 
WUAK58 PAFC 190116
SVRAFC
AKZ111-145-190200-
/O.NEW.PAFC.SV.W.0002.150819T0116Z-150819T0200Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE ANCHORAGE AK
514 PM AKDT TUE AUG 18 2015

THE NATIONAL WEATHER SERVICE IN ANCHORAGE HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  SOUTHEASTERN SUSITNA VALLEY IN ALASKA...
  SOUTHWESTERN MATANUSKA VALLEY IN ALASKA...

* UNTIL 600 PM AKDT

* AT 514 PM AKDT...DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM
  CAPABLE OF PRODUCING QUARTER SIZE HAIL. THIS STORM WAS LOCATED 16
  MILES NORTHWEST OF ANCHORAGE INTERNATIONAL AIRPORT...OR 17 MILES
  WEST OF ANCHORAGE...AND MOVING SOUTHEAST AT 10 MPH.

* THIS SEVERE THUNDERSTORM WILL REMAIN OVER SPARSELY POPULATED AREAS
  OF SOUTHEASTERN SUSITNA VALLEY AND SOUTHWESTERN MATANUSKA VALLEY.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

SEVERE THUNDERSTORMS PRODUCE DAMAGING WINDS...DESTRUCTIVE HAIL...
DEADLY LIGHTNING AND VERY HEAVY RAIN. FOR YOUR PROTECTION...MOVE TO
AN INTERIOR ROOM ON THE LOWEST FLOOR OF YOUR HOME OR BUSINESS. HEAVY
RAINS FLOOD ROADS QUICKLY SO DO NOT DRIVE INTO AREAS WHERE WATER
COVERS THE ROAD.

TORRENTIAL RAINFALL IS ALSO OCCURRING WITH THIS STORM...AND MAY LEAD
TO FLASH FLOODING. DO NOT DRIVE YOUR VEHICLE THROUGH FLOODED
ROADWAYS.

&&

LAT...LON 6133 14991 6124 15004 6125 15039 6131 15065
      6134 15068 6141 15060
TIME...MOT...LOC 0114Z 298DEG 10KT 6130 15040 

$$

CASSELL

1 follow-up statement

138 
WWAK58 PAFC 190158
SVSAFC

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE ANCHORAGE AK
555 PM AKDT TUE AUG 18 2015

AKZ111-145-190205-
/O.EXP.PAFC.SV.W.0002.000000T0000Z-150819T0200Z/
SUSITNA VALLEY-MATANUSKA VALLEY-
555 PM AKDT TUE AUG 18 2015

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN SUSITNA VALLEY
AND SOUTHWESTERN MATANUSKA VALLEY WILL EXPIRE AT 600 PM AKDT...
        
THE STORM WHICH PROMPTED THE WARNING HAS MOVED OVER NORTHERN COOK INLET 
14 MILES WEST-NORTHWEST OF ANCHORAGE INTERNATIONAL AIRPORT.
THEREFORE THE WARNING WILL BE ALLOWED TO EXPIRE. HOWEVER SMALL HAIL
AND HEAVY RAIN ARE STILL POSSIBLE WITH THIS THUNDERSTORM OVER NORTHERN
COOK INLET WATERS. FOR THIS REASON A SPECIAL MARINE WARNING IS IN EFFECT 
FOR NORTHERN COOK INLET WEST OF ANCHORAGE.

LAT...LON 6133 14991 6124 15004 6125 15039 6131 15065
      6134 15068 6141 15060
TIME...MOT...LOC 0154Z 298DEG 10KT 6130 15040 

$$

CASSELL

The office that day

Everything else NWS Anchorage, AK issued on the same UTC day.

Issued	Product	Office	Lasted
Aug 18, 5:13 PM AKDT	Special Marine Warning	AFC	32 min
Aug 18, 5:52 PM AKDT	Special Marine Warning	AFC	23 min
Aug 18, 6:15 PM AKDT	Special Marine Warning	AFC	30 min
Aug 19, 3:57 AM AKDT	Small Craft Advisory	AFC	5 days
Aug 19, 3:59 AM AKDT	Small Craft Advisory	AFC	5 days
Aug 19, 3:51 PM AKDT	Small Craft Advisory	AFC	47 hr

Nearby

Severe Thunderstorm Warnings in Alaska, 2015 Every severe thunderstorm warning in 2015

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.