.ANOTHER ROUND OF DENSE BLOWING DUST WILL MOVE ACROSS NORTHERN PINAL COUNTY AND INTO MARICOPA COUNTY...INCLUDING THE PHOENIX AREA...THIS AFTERNOON. AZZ023-190200- /O.EXT.KPSR.DS.W.0007.000000T0000Z-110719T0200Z/ GREATER PHOENIX AREA- INCLUDING THE CITIES OF...BUCKEYE...MESA...PHOENIX 600 PM MST MON JUL 18 2011 ...DUST STORM WARNING NOW IN EFFECT UNTIL 7 PM MST THIS EVENING... THE DUST STORM WARNING IS NOW IN EFFECT UNTIL 7 PM MST THIS EVENING. * AFFECTED AREA: WESTERN PORTIONS OF THE PHOENIX METRO AREA. * LOCATIONS INCLUDE: BUCKEYE...MESA...PHOENIX * TIMING: BLOWING DUST WILL CONTINUE TO OVERSPREAD THE PHOENIX AREA THROUGH 7 PM. * WINDS: SOUTHEAST 30 TO 40 MPH. * VISIBILITY: ONE QUARTER MILE OR LESS. * IMPACTS: DANGEROUS DRIVING CONDITIONS DUE TO SUDDENLY POOR VISIBILITIES. PRECAUTIONARY/PREPAREDNESS ACTIONS... IF YOU ENCOUNTER BLOWING DUST OR BLOWING SAND ON THE ROADWAY OR SEE IT APPROACHING...PULL OFF THE ROAD AS FAR AS POSSIBLE AND PUT YOUR VEHICLE IN PARK. TURN THE LIGHTS ALL THE WAY OFF AND KEEP YOUR FOOT OFF THE BRAKE PEDAL.
Monday, July 18, 2011
July 18: Re-Issued Dust Storm Warning (8:00 PM CDT)- Western Phoenix Metro Area, AZ
July 18 Severe Thunderstorm Mesoanalysis Values
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| Supercell Composite (SCP)- Higher values indicate a higher value for supercells |
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| Energy Helicity Index (EHI)- Spinning motion combined with energy in the atmosphere. Values above 4 are considered dangerous |
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| Significant Tornado Parameter (STP)- Values above 1 indicate potential for tornadic activity. |
We will be watching this cell because we believe it is in an environment dangerously favorable for tornadic motion and severe aspects.
July 18: Dust Storm Warning- Phoenix, AZ
.ANOTHER ROUND OF DENSE BLOWING DUST WILL MOVE ACROSS NORTHERN PINAL COUNTY AND INTO MARICOPA COUNTY...INCLUDING THE PHOENIX AREA...THIS AFTERNOON. AZZ023-028-190100- /O.CON.KPSR.DS.W.0007.000000T0000Z-110719T0100Z/ GREATER PHOENIX AREA-NORTHWEST AND NORTH CENTRAL PINAL COUNTY- INCLUDING THE CITIES OF...MESA...PHOENIX...APACHE JUNCTION... CASA GRANDE...FLORENCE 500 PM MST MON JUL 18 2011 ...DUST STORM WARNING REMAINS IN EFFECT UNTIL 6 PM MST THIS EVENING... A DUST STORM WARNING REMAINS IN EFFECT UNTIL 6 PM MST THIS EVENING. * AFFECTED AREA: NORTHERN PINAL COUNTY AND EASTERN PORTIONS OF THE PHOENIX METRO AREA. * LOCATIONS INCLUDE: MESA...PHOENIX...APACHE JUNCTION...CASA GRANDE...FLORENCE * TIMING: BLOWING DUST WILL CONTINUE TO OVERSPREAD NORTHERN PINAL COUNTY AND THE PHOENIX AREA THROUGH 530 PM WITH LINGERING POOR VISIBILITIES UNTIL ABOUT 6 PM. * WINDS: SOUTHEAST 30 TO 40 MPH. * VISIBILITY: ONE QUARTER MILE OR LESS. * IMPACTS: DANGEROUS DRIVING CONDITIONS DUE TO SUDDENLY POOR VISIBILITIES. PRECAUTIONARY/PREPAREDNESS ACTIONS... IF YOU ENCOUNTER BLOWING DUST OR BLOWING SAND ON THE ROADWAY OR SEE IT APPROACHING...PULL OFF THE ROAD AS FAR AS POSSIBLE AND PUT YOUR VEHICLE IN PARK. TURN THE LIGHTS ALL THE WAY OFF AND KEEP YOUR FOOT OFF THE BRAKE PEDAL.
July 18 Storm Update
It's looking like there's certainly some spinning that will be happening in the atmosphere in the Chicagoland area, as well as a lot of energy available to any storms.
However, it's seeming to be that models are conflicting on whether storms will enter the Chicagoland area. The Rapid Refresh model has indicated for at least the last 6 model runs that storms will arrive in that area between 7-10 PM CDT.
A few other sources either don't introduce storms to the area or do so at a very late hour ( 1 AM).
At this time, I would rather introduce a chance of thunderstorms for the area tonight. We will see what happens.
However, it's seeming to be that models are conflicting on whether storms will enter the Chicagoland area. The Rapid Refresh model has indicated for at least the last 6 model runs that storms will arrive in that area between 7-10 PM CDT.
A few other sources either don't introduce storms to the area or do so at a very late hour ( 1 AM).
At this time, I would rather introduce a chance of thunderstorms for the area tonight. We will see what happens.
Tonight's Storms to hit at 5 PM in Chicago
Although the overall threat for severe weather has lowered slightly, especially tornado-wise, any storms that do come through the Chicagoland area will likely hit beginning at 5 pm.
Using the Rapid Refresh (see below), I was able to pinpoint when these elevated storms will move through.
When the model shows a dark green in a cluster, it usually verifies to be yellow and red on radar reflectivity instead of dark green.
Using the 5 pm mark, I also gathered images of EHI (Spinning motion in the atmosphere combined with energy) and CAPE (instability) at that 5 pm mark.
Both images indicate a rambunctious and possibly tornadic atmosphere.
We will provide updates as needed, but keep in mind- this can change in an instant.
These storms have started to look more westerly than originally seen.
Using the Rapid Refresh (see below), I was able to pinpoint when these elevated storms will move through.
Using the 5 pm mark, I also gathered images of EHI (Spinning motion in the atmosphere combined with energy) and CAPE (instability) at that 5 pm mark.
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| EHI (Potentially tornadic storms at 1 unit and above) |
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| CAPE (Severe thunderstorm threshold at 2000) |
We will provide updates as needed, but keep in mind- this can change in an instant.
These storms have started to look more westerly than originally seen.
July 18 Severe Weather Discussion- Conditional Storm Action Day
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| Today's Hail Outlook |
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| Today's Tornado Outlook |
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| Today's Wind outlook |
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| Overall Severe Risk |
Thunderstorms ongoing this morning will provide the base for thunderstorms this afternoon on the remnant outflow boundaries, presence of cold front and weak warm air advection.
Vorticity Generation Potential is a parameter that indicates spinning updrafts, or spinning columns of rising air that create thunderstorms. Normally, the air naturally spins horizontally in the atmosphere. When these updrafts rise up, they tilt the natural rising air on its side, providing vertical spinning air for tornadoes.
Looking at models, the VGP parameter increases as the day goes on. While it does weaken into the noon hours, it is still substantial that the threat remains.
A better model to look at for spinning air is the EHI, or Energy Helicity Index. EHI's will increase in the area in question (South WI/North IL) as the days go on.
This is more worrying than the VGP. Well, I guess the VGP and EHI combined are more worrisome. But with the EHI at such a high level forecast, one can only wonder if tornadoes are possible. Below s just one of the images of EHI forecast.
The EHI is combined of both Helicity AND Energy. The Energy is the CAPE values.
Below is an image of CAPE at 3 PM CDT today.
With the spinning and energy in place, it seems that the stage is set for tornadoes.
There's just one issue- Storm Relative Helicity, a parameter that goes into the EHI, will be low. Very low in the areas mentioned.
There is still potential for tornadoes despite this setback, so we will be on the StormWatch all day.
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