Alert archive / Arizona / Mesoscale Discussions in 2012

Mesoscale Discussion 271

March 18, 2012Gila County, Arizona

The Storm Prediction Center issued this mesoscale discussion at Mar 18, 2012, 3:47 AM MST for Gila County, Arizona. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued
Mar 18, 2012, 3:47 AM MST (10:47 UTC)
Expired
Mar 18, 2012, 7:15 AM MST
In force
3 hr
Issued by
the Storm Prediction Center

County Gila County, AZ

The radar

The Flagstaff radar (KFSX), 50 km from the middle of the area, began a volume at 10:48 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

Flgstf/Belemont, AZ (KFGZ), launched 00:00Z, 10.8 hours before the alert went out and 123 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-pSkew-T log-p diagram, Flgstf/Belemont, AZ at 00:00Z on 2012-03-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Flgstf/Belemont, AZ at 00:00Z on 2012-03-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 181 square meters per square second.1939587897Sfc1 km3 km6 km9 kmRMLM
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
1412 m above ground
0-6 km bulk shear
33 kt
0-1 km storm-relative helicity
181 m²/s²
0-3 km storm-relative helicity
227 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

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

660 
ACUS11 KWNS 181048
SWOMCD
SPC MCD 181047
AZZ000-181415-

MESOSCALE DISCUSSION 0271
NWS STORM PREDICTION CENTER NORMAN OK
0547 AM CDT SUN MAR 18 2012

AREAS AFFECTED...MOGOLLON RIM AREA OF CNTRL ARIZONA

CONCERNING...HEAVY SNOW

VALID 181047Z - 181415Z

HEAVY SNOW IS EXPECTED TO DEVELOP THIS MORNING...WITH AT LEAST A
COUPLE HOUR PERIOD OF 2+ INCHES PER HOUR RATES POSSIBLE.

A VIGOROUS UPPER TROUGH CONTINUES TO GRADUALLY PROGRESS ACROSS
SOUTHERN CALIFORNIA AND NORTHERN BAJA INTO THE SOUTHERN
PLATEAU...ACCOMPANIED BY STRONG MID-LEVEL COOLING AND FORCING FOR
UPWARD VERTICAL MOTION...AND A COLD FRONT...NOW BEGINNING TO ADVANCE
THROUGH MUCH OF CENTRAL ARIZONA.  LATEST RUC GUIDANCE IS SUGGESTIVE
THAT A WEST SOUTHWESTERLY POST-FRONTAL LOW-LEVEL JET WILL GRADUALLY
NOSE FROM THE LOWER COLORADO VALLEY INTO THE MOGOLLON RIM AREA OF
CENTRAL ARIZONA BETWEEN NOW AND 14-15Z.  AS THIS
OCCURS...STRENGTHENING OROGRAPHIC FORCING FOR ASCENT IN THE PRESENCE
OF SATURATED AND COOLING THERMODYNAMIC PROFILES APPEARS LIKELY TO
ENHANCE PRECIPITATION RATES.  AND NCEP SHORT RANGE ENSEMBLE DATA ARE
INDICATING INCREASING CERTAINTY FOR A PERIOD OF HEAVY SNOW RATES OF
2+ INCHES PER HOUR THIS MORNING BETWEEN PRESCOTT AND PAYSON.  AIDED
BY DYNAMIC COOLING...IT APPEARS THAT SNOW LEVELS COULD FALL AS LOW
3000 FEET TO THE NORTH/NORTHEAST OF THE PHOENIX AREA.

..KERR.. 03/18/2012

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...FGZ...PSR...

LAT...LON   34611231 34701155 34251041 33701048 33681075 33901124
            33961176 34111211 34611231

Nearby

Mesoscale Discussions in Arizona, 2012Every mesoscale discussion in 2012

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.