810 FXUS63 KLBF 072326 AAA AFDLBF Area Forecast Discussion...UPDATED National Weather Service North Platte NE 626 PM CDT Fri Jun 7 2019 .SYNOPSIS... Issued at 322 PM CDT Fri Jun 7 2019 H5 analysis from earlier this morning had a closed low over Arkansas with a trough extending south into the northern Gulf of Mexico. A second area of low pressure was located over southwestern British Columbia with a trough extending south into northern California. HT falls of 50 to 100 meters in association with this trough were most pronounced from northern California to Washington and east to Idaho and Montana. East of this feature, broad southwesterly flow extended from southern California into south central Canada. Just east of this southwesterly flow, a ridge of high pressure was located from eastern Nebraska, north into western Ontario Canada. At the surface: Low pressure was located over northern North Dakota. A cold front extended south southwest of the low into north central Wyoming. Further south, a surface trough of low pressure extended from eastern Wyoming into sern Colorado. Winds east of the surface trough were southerly this afternoon and were gusting in the 15 to 25 MPH range. Under mostly clear skies, 2 PM CDT temperatures ranged from 82 at Ainsworth to 90 at Valentine. && .SHORT TERM...(This evening through Saturday night) Issued at 322 PM CDT Fri Jun 7 2019 A couple of rounds of convection highlight the near term forecast challenges. For tonight: Showers and thunderstorms, which initiated over the higher terrain of northeastern Colorado and sern Wyoming, will drift to the northeast into the Nebraska Panhandle this evening. As this activity moves east, it will encounter a stable environment with very weak winds and warm temperatures aloft. The LBF sounding from this morning had 8 KTS of sfc to 6KM shear and H5 temps of -9C. These temperatures are more typical of mid to late July VS. early June. AS this activity approaches the western Sandhills this evening, it will encounter the weak shear and warm temperature aloft environment, significantly weakening and diminishing convection. Through mid evening, we could see a strong storm or two in the eastern panhandle counties where shear is stronger (ie. 20-30 KTS), however, not anticipating much in the way of storms east of highway 61. That being said, went ahead and trimmed pops confining them to the western third of the forecast area. The forecast focus shifts to a cold frontal passage, and the threat for thunderstorms Saturday and Saturday night. The models have come into much better agreement with the frontal timing today. The general consensus is for a slower frontal passage which will approach a Valentine to Big Springs line by 18z Saturday. Moisture will pool ahead of the front with dew points reaching the lower to middle 60s Saturday afternoon, from Ogallala to Bassett and points east. With surface heating and the approaching cold front, thunderstorms will initiate mid afternoon INVOF the front. Steepening lapse rates along a corridor from Bassett to Imperial and North Platte will facilitate quick development of storms. Though shear is not overly strong around IE. 30 KTS, the steep lapse rates would favor a decent strong wind threat. The wind threat has support from the expected linear nature of storms along the front. Hail will be a secondary severe threat with wind being the primary threat. With this morning's new model run, SB CAPES have increased from pvs. model runs and now are running 2500-3500J/KG over swrn Nebraska at 21z Saturday. With the increased CAPES and slower frontal timing, am not surprised about the upgrade to slight risk for severe storms with the 1730Z SPC day 2 outlook. The cold front will exit the forecast area by mid evening shifting the severe threat east, however the threat for thunderstorms will continue into the overnight hours as the main upper level trough pushes into western Nebraska overnight. One final note, heavy rain appears to be a threat along the front. PWAT's are running around 1.5 inches along and ahead of the front with a forecast PWAT of 1.35 inches for North Platte at 18z Saturday. This forecast is well above the mean PWAT of 0.88 inches for June 8th. .LONG TERM...(Sunday through Friday) Issued at 322 PM CDT Fri Jun 7 2019 Drier conditions will settle in Sunday afternoon as the mid level trough of low pressure transitions east of the area. Highs pressure will build into the region Sunday night and with dry air in place, lows will be very cool across the forecast area. In fact, the latest MET and EC guidance have a mention of mid to upper 30s in the west and northwest Monday morning with MET guidance of 38 degrees for North Platte and Valentine. FWIW, the record lows for Valentine and North Platte are 37 and 38 degrees respectively Monday morning. Have trended lows cooler for Monday and am now forecasting around 40 for North Platte and lower 40s for Valentine. An upper level trough will traverse the central and northern plains Tuesday into Tuesday night. This will bring a threat for showers and thunderstorms back to the forecast area. Ridging aloft will build back into the Rockies and plains midweek with mainly dry conditions expected through the end of the work week. Highs will be well below normal with readings in the lower 70s to begin the week and mid to upper 70s toward the end of the week. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 626 PM CDT Fri Jun 7 2019 The thunderstorms across the Panhandle and northeast Colorado are expected to weaken as they move east through western Nebraska tonight. By 06z tonight, a line of sprinkles or light showers could be located along or near highway 83. The activity will continue moving east through ncntl Nebraska 06z-12z Saturday. New storm development is expected 18z-00z along and east of a line from KVTN-KIML. This activity could become fairly widespread 21z-00z Saturday afternoon. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Buttler SHORT TERM...Buttler LONG TERM...Buttler AVIATION...CDC