Weather Prediction

Currently:

10 am:
Philip, SD:
Temp: 73F, Dewpoint: 66F
Wind: SW 6 mph
Clear Skies

Frontal boundary already 1/3 of the way through most of ND, lagging back to NE/SD/WY border location. The boundary is a clear wind shift, but temperatures and dewpoints do not drop substantially behind it. Actually, currently the temperatures are warmest behind the front in SW Montana (mid-80s). The current satellite shows high level, and a few mid level, clouds out ahead of the boundary in western SD, ND, and into WY/NE. These high level clouds should keep temperatures down a bit today as compared to the previous forecast. Definitely lower than the 99F the NWS was forecasting.

Today:

Cloudiness, which wasn't forecasted well by the models yesterday, looks to help keep temperatures down. There isn't a single 80F temperature in all of SD or ND, which is similar to this time yesterday. At 10 am yesterday Philip was 76F, 3 degrees warmer. However, today 850 mb temperatures are much warmer, and yesterday had 3 hours of flatline temperatures. So, if a 2 degree warming for the three hours had occur, 94F looks easy. 850 mb temps are highest at 2/3 pm before the boundary comes through Philip at 29C, or supportive of 37C/98F. This is down from the possible 103F from yesterday. With the cloudiness, cooler starting temperature, and frontal boundary moving through at 2 pm ish, the high temperature should have difficulty maxing out at 98F, so will go with a few degrees cooler and 95F. Still a very hot day. If any convection develops with the front, we could see even cooler temperatures, closer to 90, if an anvil or storm travels directly over Philip. There shouldn't be much rainfall in Philip today as the CIN will stay up, reducing the chance of a thunderstorm, but it could still happen. 20% chance. (My forecast yesterday: 96F; NWS: yesterday: 99F, today: 96F)

Tonight:

This is the fun forecast, with some models predicting rainfall, and some not. The SPC seems confident in a few thunderstorms developing in the WY mountains and Black Hills into the evening. The storms could produce a nocturnal MCS and travel out into the plains within the flow aloft. These storms look to be initiated by the higher terrain and a Theta-e axis, decent CAPE (500-1000 J/kg), and eroding CIN by 00Z. Dewpoints will be 50-55F in WY to 65F in central SD. These dewpoint temperatures should slowly decrease through the night in the Philip area, with any rain dropping the temperature quickly towards the dewpoint, if not a bit lower as the dewpoint temperature continues its drop behind the frontal boundary. Rainfall looks to be fairly likely south of Philip, but not to the north. In other words, Philip will be right on the boundary between precipitation and none. Thus, a 40% chance of precip tonight, and 0.05 inches forecasted. With a northerly wind at 5-10 mph, dewpoints slowly dropping to near 60F by morning (per MOS), and ETA/GFS MOS forecasting 65/64F respectively, it looks like the low should be in the lower to mid-60s. I will go with 63F tonight, consistent with the lower end trend throughout the last two weeks. (NWS: 63F)

Tomorrow:
The SPC has put out another slight risk chance of severe weather, but mainly for NW WY for hail. Dewpoints will stay up in NW WY, but fall sharply in SW MT. This will lead to a little dryline in the WY/MT border region. CAPE will increase to 500 J/kg with an uncapped environment in NW WY. Add in terrain forcing and a few storms should develop. Helicity values will be between 50-150, supportive of some twisting in the atmosphere, and possible super cell structures. However, the Philip area will be capped and have no CAPE, thus reducing the possibilities that the storms should hold together into the evening and travel out into the plains before nightfall. Thus, Philip only really has a minimal chance of an evening storm outside of lingering showers in the morning from the nocturnal MCS. I say no rain. As for temperatures, some lingering high level cirrus should travel into the area as convection develops over the higher terrain to the west, but other than this, temperatures should approach 850 mb temp (23C) potential, which is 31C/88F. ETA/GFS MOS say 92/88F, and NAM RAW is 91F. With a little bit of cloud, it might hold the temperature down a degree, so 87F. (NWS: 92F)