Previous Day
Another bust in and around the Tucson area. This time, it was 7 out of 8 runs from the 0Z to 12Z initializations. The only one that got it 'right' was the 12Z WRFRR as it had only limited activity everywhere, including north of Phoenix. This is the worst I've seen the model perform with what I though have been quite good initializations
I continue to be suspect the moisture profile from Guaymas as this morning it's again over 1/2 inch above any of the surrounding Suominet stations. The symptom is that the model runs have Tucson too moist in the afternoons. It might be because of Guaymas or for some other reason. Below is a IPW example from the day before yesterday. (black observed)
Initializations
As I mentioned above, there is a big wet bias in all the 12Z initializations around Hermosillo/Guaymas. The 12Z RR is especially bad not only in NW Mexico but also in New Mexico.
Here's the Guaymas sounding from this morning. It's likely the sondes are old as Guaymas hasn't launched regularly in 2 years.
A MCS is decaying west of Hermosillo while scattered clouds and a few showers across SE Arizona. Observed temperatures are quite close to observed thus there is little impact from that activity. The NAM had no clouds over much of the state while the RR and the GFS had some. In any case, it is a non-issue.
The 500mb high centers are NW of Vegas and near El-Paso and no larger scale cyclonic circulations were noted. A MCV is moving out over the GofC from the overnight Sonoran MCV. The initializations look fine. Normally I'd say that the initial conditions look good, but with the unknown situation at Guaymas, and the past runs, model confidence for southern Arizona is low.
Day 1, July 26
Moisture remains moderate across the state. Interesting to see how west eastern NM is also which may keep the typically dry easterly winds across western NM fairly moist.
Mid-level air is fairly warm with -5 to -6C around the area and steering winds continue to be light and variable with only weak easterly flow across southern Arizona. Looks like another day with scattered high elevation storms that don't move much and produce very heavy rain.
CAPE is forecast to be much less today across the state as moisture has decreased slightly and temperatures have increased aloft.
Only isolated to scattered activity over the usual locations this afternoon.
Limited or no activity in Tucson or Phoenix with a forecast skew-t like this: limited CAPE, fairly shallow PBL, and weak mid level winds.
The model runs are forecasting a few storms over the higher elevations around Tucson this evening. My guess is that this may be overdone.
Day 2, July 27
The situation with the weak steering flow finally improves as the high center moves north putting much of Arizona in NE flow of 10 to 20 knots. Mid-level air is still quite warm. So some good, some bad.
The low-level flow becomes more complex as up on the plateau of NE Arizona, drying NE winds are present. However, moisture continues to remain about the same over much of the rest of the state as a weak surge is underway. The backdoor dryline over NE Arizona may act as a convergence line helping to initiate convection on top of the typical diurnal pattern there. So two positives so far.
CAPE is forecast to be in the moderate range across much of southeastern Arizona. This is likely to be the active area tomorrow.
The general idea is scattered deep convection forms over the White Mountains and over the Gila Mountains of western NM and moves to the SW. Outflows move ahead of storms and force additional deep convection, with this mechanism repeating allowing the line to move faster than the mid-level steering. An Arizona version of a tropical squall line.
By late afternoon, scattered storms move into SE Arizona with Tucson being on the edge of the activity.
Areas of very strong winds are likely due to the large inverted V profile.
There is a slight chance that few areas of deep convection also form in the Phoenix area tomorrow evening.
Another bust in and around the Tucson area. This time, it was 7 out of 8 runs from the 0Z to 12Z initializations. The only one that got it 'right' was the 12Z WRFRR as it had only limited activity everywhere, including north of Phoenix. This is the worst I've seen the model perform with what I though have been quite good initializations
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| 12Z WRFRR |
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| 12Z WRFNAM |
I continue to be suspect the moisture profile from Guaymas as this morning it's again over 1/2 inch above any of the surrounding Suominet stations. The symptom is that the model runs have Tucson too moist in the afternoons. It might be because of Guaymas or for some other reason. Below is a IPW example from the day before yesterday. (black observed)
Initializations
As I mentioned above, there is a big wet bias in all the 12Z initializations around Hermosillo/Guaymas. The 12Z RR is especially bad not only in NW Mexico but also in New Mexico.
Here's the Guaymas sounding from this morning. It's likely the sondes are old as Guaymas hasn't launched regularly in 2 years.
A MCS is decaying west of Hermosillo while scattered clouds and a few showers across SE Arizona. Observed temperatures are quite close to observed thus there is little impact from that activity. The NAM had no clouds over much of the state while the RR and the GFS had some. In any case, it is a non-issue.
The 500mb high centers are NW of Vegas and near El-Paso and no larger scale cyclonic circulations were noted. A MCV is moving out over the GofC from the overnight Sonoran MCV. The initializations look fine. Normally I'd say that the initial conditions look good, but with the unknown situation at Guaymas, and the past runs, model confidence for southern Arizona is low.
Day 1, July 26
Moisture remains moderate across the state. Interesting to see how west eastern NM is also which may keep the typically dry easterly winds across western NM fairly moist.
Mid-level air is fairly warm with -5 to -6C around the area and steering winds continue to be light and variable with only weak easterly flow across southern Arizona. Looks like another day with scattered high elevation storms that don't move much and produce very heavy rain.
CAPE is forecast to be much less today across the state as moisture has decreased slightly and temperatures have increased aloft.
Only isolated to scattered activity over the usual locations this afternoon.
Day 2, July 27
The situation with the weak steering flow finally improves as the high center moves north putting much of Arizona in NE flow of 10 to 20 knots. Mid-level air is still quite warm. So some good, some bad.
The low-level flow becomes more complex as up on the plateau of NE Arizona, drying NE winds are present. However, moisture continues to remain about the same over much of the rest of the state as a weak surge is underway. The backdoor dryline over NE Arizona may act as a convergence line helping to initiate convection on top of the typical diurnal pattern there. So two positives so far.
CAPE is forecast to be in the moderate range across much of southeastern Arizona. This is likely to be the active area tomorrow.
By late afternoon, scattered storms move into SE Arizona with Tucson being on the edge of the activity.
Areas of very strong winds are likely due to the large inverted V profile.
There is a slight chance that few areas of deep convection also form in the Phoenix area tomorrow evening.
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