Area forecast discussion National Weather Service Bismarck ND 649 am CDT Wednesday Jun 19 2013 Update... issued at 647 am CDT Wednesday Jun 19 2013 No significant changes to previous forecast. Still uncertainty as to potential for convection to development this afternoon within initial warm air advection. Convection spreading into the west/north is a better bet for late tonight. && Short term...(today and tonight) issued at 351 am CDT Wednesday Jun 19 2013 There are multiple concerns for the short term period including thunderstorms / severe weather possibilities...and the potential for a Wind Advisory in the southwest. A warm front located from central Montana into eastern Wyoming is expected to lift north today into tonight. The boundary is expected to be located from northeast Montana into south central North Dakota by early Thursday morning. Increasing 850 mb warm air advection associated with the warm front and an increasing low level jet should provide support for a few thunderstorms later this afternoon into tonight. The latest 4km WRF-nmm suggests thunderstorms could begin in parts of central North Dakota this afternoon before increasing in coverage later this evening. Another concern is that thunderstorms which develop later today across across parts of central and eastern Montana will move into western North Dakota tonight in the form of an mesoscale convective system. MLCAPE values of 1500-2500 j/kg are shown by the 19.00z NAM this afternoon into tonight across much of central and western North Dakota. Deep layer shear will increase tonight in concert with the low level jet...which should help enhance the severe weather threat. Will focus the main severe weather potential in the grids across western North Dakota as per the latest day 1 outlook from the Storm Prediction Center. However...if storms develop this afternoon in parts of central North Dakota as per the 4km WRF- nmm...those too have potential to be strong to severe. Heavy rain could accompany the thunderstorms...especially tonight...as precipitable water values increase to near 1.75 inches in the northwest part of the state tonight. In addition to the thunderstorm concerns for today / tonight...another issue will be the potential for advisory level winds today in the southwest part of the state. Forecast soundings suggest mixing will be deep with near 40 kts of wind available at 800 mb. The latest GFS numerical guidance for Baker Montana forecasts sustained wind speeds near 29 kts...so after coordination with weather forecast office Rapid City have opted to issue a Wind Advisory in parts of southwest North Dakota for today into this evening. Long term...(thursday through tuesday) issued at 351 am CDT Wednesday Jun 19 2013 The main forecast issues through the long term period are severe weather potential and timing issues through Friday. Strong to potentially severe storms from an organized storm cluster may persist across northern counties Thursday morning. Otherwise...storm re-intensification is expected during the afternoon/evening hours along a strong moisture convergence axis with dewpoints in the upper 60s and precipitable water values approaching 2 inches. Isolated flash flooding will be a concern...along with hail/damaging wind threat...especially along and east of Highway 83. Continue to favor slower European model (ecmwf)/GFS solutions regarding higher probability of precipitation across the east for Thursday night. The timing issues persist into Friday...and again have leaned toward more widespread storms per the European model (ecmwf). Total rainfall amounts of 1 to 2 inches...isolated higher...will be possible across the north through Friday night. The closed upper low across the Pacific northwest is expected to finally move through the northern plains over the weekend...supporting additional rounds of showers and thunderstorms. Near seasonal temperatures are expected through the weekend...followed by some warming early next week. && Aviation...(for the 12z tafs through 12z Thursday morning) issued at 647 am CDT Wednesday Jun 19 2013 VFR ceilings and visibilities will prevail to start the forecast...with a veil of high clouds across the region. Winds are expected to increase this morning...with the strongest winds developing at kdik where gusts to near 35 kts are possible this afternoon. The chance of thunderstorms will increase...especially after 20.00z as a warm front moves into the region. Will carry prob30 groups this evening into tonight to account for the thunderstorm possibilities. && Bis watches/warnings/advisories... Wind Advisory from 9 am this morning to 9 PM MDT this evening for ndz031>033-040-041-043-044. && $$ Update/long term...rp Kinney short term/aviation...ck