Monday, June 30th: Forecast

Currently:

The western United States are in the middle of an upper level ridge, with the Dakotas in the entrance region, resulting in northerly flow at the 500 hPa level. At 850 hPa, the wind shifts to out of the south with the crest of the ridge already east of the western Dakotas. At the surface the winds match up with the 850 hPa level and are out of the south in the western Dakotas. Currently (10 am) the temperature is 74F, 54Fd, and winds SSE at 13 mph in Philip. Skies are clear throughout the Dakotas.

Today:

Learning from yesterday's fiasco with the high temperature, it is important to look at exactly how high mixing will occur. Yesterday mixing was weak with winds only in the 5-8 mph range. Today, with winds already up to 13 mph, it is likely that there will be better mixing. However, RAW NAM and GFS/ETA MOS show wind speeds should decrease in the afternoon. Mixing looks to reach 780 mb. This again would support using 850 mb temperatures for an indication of the maximum temperature (adding 8C to the 850 mb temperature). In the afternoon the 850 mb temp will be 23C, which results in 31C or 88F for the high temperature today. RAW NAM, and the MOS all agree the high will be 91F today. Considering yesterday was right in line with the 850 mb temp potential with clear skies (like today), even with warm MOS temps, it makes sense to stick with the 850 potential at 88F. (NWS: 88F)

Tonight:

Clear skies, once again. However, this time the dewpoint is forecast to be much warmer, in the mid to upper 50s. The MOS have been very good at forecasting low temperatures, unlike the raw, and show the low at 58/57F, close to the dewpoint temp. The RAW NAM is predicting 61F. I will stick close to the MOS, going with the lower number 57F. Tomorrow night the low temperature will start to get more interesting with clouds in the area. The only issue tonight is a strong nocturnal low level just only 500 meters above the surface. If the atmosphere does not decouple, or de-decouples (ha!) then the low might not reach its potential. However, I think this wont happen. So, 57F. (NWS: 59F)

Tomorrow:

This should be the hottest day of the week, along with the first chance of precipitation. GFS/ETA MOS are both forecasting 97F for the high. The RAW NAM is much the same with 96F for the high. There should be some mid-level clouds and possible thunderstorms over the higher terrain as an upslope flow commences and increased dewpoint temperatures. GFS MOS is a bit cooler at 54F dewpoints, but the ETA MOS says 59F. RAW NAM brings the dewpoint down to 50F in the afternoon. This is likely because of the weak winds and possible weak mixing. Either way, 50F dewpoints look likely. I don't think Philip will see any rain tomorrow, but the clouds from convection off of the hills might reduce afternoon temperatures. 850 mb temps are 27C in the afternoon, or supportive of 35F, which is 95F. With clouds in the picture and a 95F maximum, I will go just below this at 93F. I would be very surprised to see highs in the upper 90s tomorrow, but it could be possible if no clouds move in and the 850 temps are off by a degree C. (NWS: 90F)

Next few days:

Upslope convection should increase over the next 2-3 days. Temperatures, on the other hand should decrease before the strong ridge moves overhead into the weekend. Next week should be very warm in the western ridge.