Greetings all, What a difference a week makes. Last week we were describing snowfall at 5,500 feet and this week our precipitation map has painted in many of the dry spots thanks to moisture that got entrained from what was Pacific Hurricane, “Bob”. Our colleagues in wildland fire in the southeastern U.S. refer to these kinds of weather systems as, “Rain with a name”. In other words tropical moisture such as the anomalous event we experienced over the past 5 days can really be a game changer – at least for awhile. (1) NWS Observed 7-Day Precipitation. That storm pumped moisture through the southwest U.S. and Great Basin before an upper-level low pressure system tapped into it last weekend. It churned over the Northern Rockies for four days with easterly winds bringing over seven inches of upslope rain to the Continental Divide in west-central Montana. There was even some snow that closed the Beartooth Highway in southwest Montana’s PSA 9 on Monday 6/18. On top of the generous precipitation we received the first week in June, we further mitigated dry fuels in North Dakota as well, which has helped with the ongoing drought conditions there. (2) US Drought Monitor. At the lowest extreme, the areas in north Idaho and northwest Montana only received a quarter to one half inch of precipitation this week and the fuels charts continue to show near-record dryness there. Much cooler temperatures were recorded this week across the region, with the exception of eastern North Dakota. (3) Departure from Normal Temperature. It was slightly warmer-than average there, but further west, it was well-below seasonal conditions in south-central Montana. Another wide swing of conditions is expected for the remainder of this week with a back-and-forth of ridge/trough/ridge through this weekend. Severe weather with heavy rain, gusty winds, and large hail is expected with a robust shortwave trough in southwest Montana late tomorrow afternoon. Otherwise, beneficial wetting rains are going to help matters in the Idaho Panhandle tomorrow. We should start to settle into a more southwesterly flow regime by late Sunday and early next week. That will continue to bring showers and thunderstorms to the Northern Rockies Geographic Area, however, it will also respond to high pressure that will build from the central Rockies through the Dakotas. We may see a sharp temperature contrast developing from west to east with warmth on the plains, according to NOAA’s Climate Prediction Center. This could even start drying out soils and fuels over North Dakota in earnest after the soggy start to the month . (4) GFS Predicted Soil Moisture Anomaly for the week of 20-27 June. It’ll be tough to beat out those precipitation totals for the preceding two weeks. The Weather Prediction Center is calling for the driest areas to remain the Idaho Panhandle, northern Montana, and most of North Dakota. (5) WPC 7-Day QPF ending on 28 une. Cheers for Now. Next week we’ll share some great photos from the roof of the NRGA. Coleen

NRGA Weather-Climate Update

Wednesday 20 June, 2018

Rain with a name “Bob”

1) NWS Observed 7-Day Precipitation, Ending 0600 MDT 20 June

2) US Drought Monitor, Issued 0800 MDT 14 June

3) NOAA 7 – Day Surface Temperature Anomalies (F)

4) GFS Predicted Soil Moisture Anomaly 20 June

5) Weather Prediction Center 7-Day Quantative Precipitation Forecast, Valid 20 to 28 June

Coleen Haskell Meteorologist, Predictive Services USFS – Northern Rockies Coordination Center 5765 West Broadway, Missoula, MT 59808 (406) 329-4875