Tuesday, June 06, 2017

Continued Hot But With Bit Of Chance For Thunderstorms

Have now had three days with high temperatures of 104 F. The current NWS forecast inches those up over 105 F next couple of days. The model forecasts are now indicating some chance of thunderstorms over southeast Arizona tomorrow and Thursday.

Above is 07:00 am MST view of the Catalinas, showing dirty air over the city and some middle cloudiness over the mountains. The 00 UTC GEFS plumes for QPF at the airport (below) indicate that some members are forecasting showers tomorrow/Thursday. Note that the operational GFS (blue) is, however, a wet outlier.

Forecasts here are from the 00 UTC run of the WRF-GFS at Atmo. Composite radar echoes above are forecast at 05:00 pm tomorrow afternoon, while sounding forecast below is valid at 04:00 pm. The surface CAPE indicated is excessive, but mixed layer CAPE is present. Note that cloud bases would be above 600 mb, indicating a potential for strong outflow winds if storms develop. The 10-m wind forecast at bottom is valid at 05:00 pm. 

Since the operational GFS is wet, the best chance for storms will be on mountain flanks, while at low elevations high-based sprinkles may produce local gusty surface winds and perhaps a bit of blowing dust. There may also be dry lightning, contributing to high wildfire dangers.

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