Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/17/17

Area Forecast Discussion
National Weather Service Cheyenne WY
516 PM MDT Sat Sep 16 2017 .SHORT TERM...(This evening through Monday night) Issued at 200 PM MDT Sat Sep 16 2017 Upper trough swinging across northern Wy into the northern plains now with energy clipping the north part of the CWA and setting off some showers. Expect these to move eastward for the rest of the afternoon before ending. A cool surface high will settle over the northern plains tonight and with clear skies should see a chilly night. Min temps Sunday morning should get close to freezing over parts of the northern and western CWA so have opted to post a frost advy for those typically cool areas for later tonight into Sunday morning. Warmer temps make their return Sunday as the surface high moves into the central plains and southerly winds set up over the CWA. An impulse will move across the area late Sunday and set off some showers and a few storms mainly east of the mtns Sunday afternoon with activity moving across the Panhandle Sunday evening. Warm and dry Monday with lee troughing over the high plains. Rather breezy over western areas both Sunday and monday afternoon. .LONG TERM...(Tuesday through Saturday) Issued at 200 PM MDT Sat Sep 16 2017 A closed low over southwest Canada will remain nearly stationary through the period. A series of upper troughs will impact the Intermountain West, Rockies and High Plains. These systems and a couple of cold frontal passages will maintain a showery pattern through the week. Best opportunity for thunder will be Tuesday afternoon with the first cold front moving through the CWA. It will be quite breezy along and west of the Laramie Range Tuesday with westerly winds gusting to 40 mph. Highest mountain elevations could see a couple of inches of snow Tuesday night and Thursday night. High Temperatures Tuesday through Thursday slightly above seasonal normals, then cool to slightly below normal Friday and Saturday after the second cold front. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 514 PM MDT Sat Sep 16 2017 Some concern with the return of stratus tonight, but it will be more patchy than what we saw last night. Best locations using latest HRRR would be KAIA and possibly KCYS. Trended TAFs for these two airports. Will see what later HRRR output shows before introducing more widespread IFR. Windy again Sunday. && .FIRE WEATHER... Issued at 200 PM MDT Sat Sep 16 2017 A cool night is expected tonight with some frost in low-lying areas, mainly over western and northern districts. Warmer conditions will return Sunday into early next week with dry weather for the most part. A disturbance should set off some showers and a few storms east of the mountains late Sunday into Sunday evening. Breezy conditions will also occur over western districts both Sunday and Monday afternoon but minimum humidities should stay generally above 25 percent both days. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...Frost Advisory from 2 AM to 8 AM MDT Sunday for WYZ101-102-105- 109-115. NE...None. && $$ SHORT TERM...RE LONG TERM...MAJ AVIATION...GCC FIRE WEATHER...RE
Area Forecast Discussion
National Weather Service Dodge City KS
626 PM CDT Sat Sep 16 2017 ...Updated Aviation... .SHORT TERM...(This evening through Sunday) Issued at 100 PM CDT Sat Sep 16 2017 Quite a difference in the models this afternoon concerning possibilities for convection across south central Kansas. The HRRR has really only been supported by the WRF-NMM and has been consistent run after run today supporting a cluster of thunderstorms initiating near the cold front-dryline intersection in northwest OK, and moving quickly northeast over the areas of Comanche Barber Pratt and Stafford counties between 4 and 7 pm. There is about 30kts of 0-6 km bulk shear, and and LHP value in the lowest bin (still thinking half dollar or slighlty larger size hail for max size), and possibility of locally severe wind gusts. Several of the other CAM`s fail to produce convection across our local counties. As the boundary spreads south later tonight, low level stratiform clouds will redevelop and overspread much of the area by early Sunday morning. The trend of the low level cloudiness will be one of the forecast challenges for Sunday temperatures, as winds remain light easterly and upslope under a surface high pressure ridge. It could remain cloudy all day over the entire forecast area. .LONG TERM...(Sunday night through Saturday) Issued at 100 PM CDT Sat Sep 16 2017 Latest 12UTC GFS continues to show weak mid level differential vorticity moving through the downstream flow Sunday night, which may account for additional elevated showers and thunderstorms through the region. Light and variable or even easterly winds Monday should be replaced by south winds as another warm front develops by Monday night. This will setup a hot downslope flow day on Tuesday, where the GFSMOS has 95 degrees at DDC. Both the GFS and EC meet this hot airmass with another cold front on Tuesday night, which should easily knock temperatures back down into the low 80s on Wednesday afternoon. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 623 PM CDT Sat Sep 16 2017 VFR conditions give way to MVFR conditions Sunday morning around 10Z for all the airports. Light east winds leading to upslope flow should keep the lower cloud ceilings in place for the rest of the time period Sunday with a few pockets of light rainshowers. VFR conditions could once again be possible by late in the time period around 22Z. && .PRELIMINARY POINT TEMPS/POPS... DDC 55 77 62 90 / 20 30 30 20 GCK 53 74 60 88 / 20 30 30 10 EHA 51 76 59 89 / 10 20 20 10 LBL 56 78 61 91 / 20 30 30 20 HYS 53 72 61 85 / 20 20 50 20 P28 64 79 65 89 / 40 40 30 30 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Russell LONG TERM...Russell AVIATION...Tatro
Area Forecast Discussion
National Weather Service Des Moines IA
650 PM CDT Sat Sep 16 2017 ...Updated Aviation Discussion... .SHORT TERM.../Tonight through Sunday/ Issued at 330 PM CDT Sat Sep 16 2017 Bottom Line up Front... Severe weather potential from around 4 pm until midnight or so remains the biggest threat. All modes of severe weather are on the table, with large hail and damaging winds being the primary threats, and a few tornadoes being the secondary threat. Synoptic-scale... 19z Non-operational GOES 16 data picking up on two stronger upper lows phased within a longwave trough that digs down through the Four Corners Region. These lows have decent westward tilt with height as the sfc reflection lows are centered over northern Minnesota and eastern Nebraska. The northern sfc low is undoubtedly the stronger of the two lows, as the more southerly low has been losing organization throughout the daytime along its northeasterly trek. Attendant to the northern low is a decently strong cold front that drapes from north to S/SSW and phases with the southern low. As this boundary propagates east and southeast, it will be the main focusing mechanism for the strong to severe potential this evening into the overnight hours... Short-term models starting to lock into placing the boundary south and east of the DMX CWA between 12z and 15z Sun. Resultingly, Sunday afternoon looks much cooler as 850mb temps drop a solid 5C. With scattered cloud cover around, highs in the low to mid 70s seems a plausible forecast. Mesoscale... Showers and storms have been fairly widespread across the CWA throughout the daytime today. CAPE values have been around 500 J/KG, the main limiting factor for the storms reaching severe levels. As expected, HRRR (warm-start) has been outperforming other models... though it still has not perfectly handled storms through today. During peak heating, SPC mesoanalysis showing SBCAPE values reaching 2000 J/KG to 2500 J/KG, so plenty sufficient instability to work with. Meanwhile, Low-level lapse rates very high, reaching 9 C/km...and mid-level lapse rates reaching 7 C/KM suggest hail will be a threat. Fcst soundings have been consistent in showing storms becoming more sfc-based with boundary approaching, making hail a realistic threat. DCAPE values around 1000 J/KG, with fairly unidirectional winds, so damaging winds also a threat. Tornado threat not great, but not non-zero. Between 00z and 03z, In southern/SW Iowa, low-level theta-e difference perks up, phased with higher CAPE values and 0-3km bulk shear vectors flowing close to perpendicular to this CAPE gradient. Hodograph for svr potential looks okay... not great, but not poor. .LONG TERM.../Sunday night through Saturday/ Issued at 330 PM CDT Sat Sep 16 2017 Active early in the week as high pressure moves across southern Minnesota Sunday night then moisture lifts back north late Sunday night into Monday. A strong short wave will arrive during the day on Monday and will lead to increasing showers and thunderstorms and a good chance for widespread precipitation. PWAT values will rise back to above 1.5 inches and near 175 percent of climatology and will bring the potential for rainfall amounts in excess of 1 inch in some areas. High temperatures on Monday will remain cool with highs mainly in the 60s and lower 70s due to the precipitation and clouds. Warmer weather will again return Tuesday with an area of low pressure developing to the west and a warm front lifts north into Iowa leading to highs back into the 80s. A large upper level low pressure system over southwest Canada will be a big influence on Iowa for mid to late week. This system will drive a strong short wave through the Midwest Wednesday and another brief cool down. The large upper low will help create a deep trough over the western CONUS late this week while a subtropical high amplifies into the Ohio Valley. This will lead to steep southwest flow developing over Iowa and potentially another run at 90 degrees by Friday. Given this flow, current solutions are likely too fast moving the boundary into Iowa through the southwest flow which should stall it to the west. The end of the week should end on a very warm and mostly dry not before a potential stormy next weekend. This type of pattern may be the end of the warm stretch and lead to a transition to more fall like weather. && .AVIATION.../For the 00Z TAFS through 00Z Sunday evening/ Issued at 650 PM CDT Sat Sep 16 2017 MVFR to IFR stratus moving into northern Iowa and will impact FOD and MCW by 02z at the latest. The onset of this stratus deck appears to be around 700-900 feet before improving to 1700-2300 feet. Confident FOD and MCW will see these IFR ceilings but will likely increase to MVFR later this evening. For now, only have MVFR ceilings mentioned at DSM and ALO as lower confidence to mention for timing, but likely move in by around 06-08z. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...Kotenberg LONG TERM...Donavon AVIATION...Podrazik
Area Forecast Discussion
National Weather Service North Platte NE
604 PM CDT Sat Sep 16 2017 .SYNOPSIS... Issued at 315 PM CDT Sat Sep 16 2017 Upper low over eastern MT continues to lift northeast into ND with lead PV anomaly over western SD early this afternoon. Another PV anomaly located across southern WY will also be pulling northeast tonight. At the surface weakening high pressure across NE as pressure falls increase across the western High Plains. Cold front that came through the area last evening now located across central KS into eastern MN, cutting through far southeast NE. Mid level cloudiness atop lower clouds remains across north central NE, with light echoes on radar waning. && .SHORT TERM...(This evening through Sunday) Issued at 315 PM CDT Sat Sep 16 2017 Height rises over the central Rockies behind the exiting upper level low over the northern Plains will induce a more zonal flow over the lee of the Rockies this evening. This will promote surface pressure falls over the High Plains and a resulting return flow prior to advancing high pressure to come later overnight. This will result in upslope flow further west and a mid level warm advection pattern and associated isentropic lift this evening. Mid level cloudiness and isolated to widely scattered rain showers should develop this evening/overnight as per the HRRR. Will include some cloud cover in the western and southwestern portion of the area tonight for this. While not a big deal from a precipitation perspective, the cloud cover should keep the southern portion of the area from dropping into the 30s overnight assuming it happens as expected. This is as a result of surface high pressure dropping south and settles in over the central part of the state early Sunday morning. Recent MOS guidance has warmed overnight lows a few degrees in the south due to cloud cover in the south as discussed, but remains fairly constant further north and west where mid 30s are likely. Patchy frost possible there. Did include patchy frost in the northwestern areas which was also in prev forecast. As previously mentioned area of upper height rises moves in to the northern Plains during the day Sunday broader surface pressure falls develop over the lee of the Rockies. This will set up a return low level flow through the day. Cloud cover is not consisent in the models with more precip shown in the HRRR in the morning, after a cool start. Atmospheric return flow increases during the day and low level moisture returns into the High Plains. This, combined with southwesterly flow aloft will bring an elevated mixed layer and available mid level instability which is indicated by a narrow area of CAPE in the Panhandle by afternoon. Morning precip should weaken and went with a mainly dry forecast after that. .LONG TERM...(Sunday night through Saturday) Issued at 315 PM CDT Sat Sep 16 2017 An active week ahead as a large upper level trough digs south through the western portions of the United states. Our region will remain on the eastern periphery of the upper trough with southwest flow aloft to dominate for the first half of the week, then a more south-southwest flow aloft for the second half of the week as the trough digs farther south into the southwest U.S. The first chance for rain will be Sunday night into Monday morning. Strong mid level warm air advection and increasingly moist southerly low level jet, will lead to significant destabilization in the mid levels of the atmosphere. Looks like a decent set up for elevated thunderstorm development, and have this covered in the forecast with some fairly decent pops. Another shot for rain enters the picture late Tuesday afternoon and Tuesday night. This looks most likely for northern Nebraska, which will be in closer proximity to a decent wave moving across the Dakotas. SPC continues to highlight northern Nebraska for potential severe during this time. Moisture, instability and shear look decent and agree some stronger storms are possible and will highlight in the Hazardous Weather Outlook. A cold front will scour out the moisture for Wednesday through Thursday night and expect dry conditions during this time. For Friday into the weekend, rain/thunder chances will increase, as both quality low level moisture and upper level dynamics become favorable for precipitation development. Certainly could be some stronger storms as dew points rise into the 60s and south-southwest flow aloft increases as the upper trough approaches from the west. Temperature wise, it is looking like a fairly warm week, with highs ranging from the mid 70s to mid 80s. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 556 PM CDT Sat Sep 16 2017 Some increase in mid level cloudiness is expected across the area toward sunrise Sunday morning, otherwise mainly clear skies are expected this evening. An isolated shower is possible along and south of interstate 80 Sunday morning. Winds will be light with VFR all areas. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Stoppkotte SHORT TERM...Stoppkotte LONG TERM...Taylor AVIATION...Taylor
Area Forecast Discussion...UPDATED
National Weather Service Lubbock TX
915 PM CDT Sat Sep 16 2017 .UPDATE... The weather has quieted down across the forecast area as of 9 pm. There is still a small t-storm complex in the northern Rolling Plains and far southeast Texas Panhandle that will be mainly impacting Childress and northern Cottle Counties through about 10 pm. We also have another batch of showers and t-storms moving E-NE out of east-central NM into the western South Plains, This activity has some lightning associated with it, but it should remain on the disorganized/weak side as it moves into a lower instability environment farther to the east. Later tonight, we could see additional shower and t-storm activity approach the forecast area from the southwest as the next shortwave in the southwest flow aloft edges toward the region. Right now, an isolated mention in the forecast seems lke it will suffice. && .PREV DISCUSSION... /issued 643 PM CDT Sat Sep 16 2017/ AVIATION... Thunderstorms are roaming near/over all three terminals to kick off the TAF cycle. Storms over KLBB should quickly shift east of the terminal, though they could persist another 1-3 hours at KPVW and KCDS. Expect gusty and erratic winds and brief heavy rain (and associated reduced visibilities) with the strongest cores. More isolated showers and thunderstorms will be possible late tonight into Sunday morning, with scattered redevelop Sunday afternoon. Timing and coverage of convection beyond this evening`s round is uncertain and has been excluded from the TAFs at this time. Outside of any storm influences VFR and relatively light (though somewhat variable) winds will be the rule. PREV DISCUSSION... /issued 341 PM CDT Sat Sep 16 2017/ DISCUSSION... Unsettled SW flow aloft looks on track for another round of isolated to scattered storms later today and overnight. Water vapor imagery indicated a narrow dark axis (subsidence) extending from near El Paso northeast to Amarillo, which aligns well with the northern terminus of an upper jet. This jet coincides nicely with a surface trough and ample surface heating (0-3 km lapse rates as steep as 10*C) which has brewed SBCAPEs of 500-1000 J/kg thus far. Agitated cumulus have blossomed along this axis of strong heating, with maturation to storms noted near Levelland as of 310 PM. Greater coverage of storms in Lea County, NM could prove to be the bigger show locally as 20-30 knots of steering flow sends this activity into the South Plains through the evening. Feeling is the HRRR remains overblown with coverage of precip, but the overall scenario of storms tracking NE and focusing near the aforementioned surface trough appears very plausible. Healthy DCAPE of nearly 1500 J/kg will favor microbursts with some of the stronger cores, which was addressed well in the midnight shift`s HWO. With no real upper trough evident overnight, convection may not wane much at all after midnight thanks to the lingering upper jet. SW flow aloft will veer a bit more W-SW on Sunday as an elongated ridge retrogrades from the Gulf to South TX. Upshot of this is that the mid-level moist axis, surface trough, and upper jet should all be nudged farther north into the Panhandle, but remain close enough to warrant additional PoPs for much of our region. By Monday, drier westerly flow should vaporize a large extent of the elevated moisture plume and serve to ratchet high temps up. This warming looks most pronounced on Tuesday as most of the CWA resides west of a surface trough/weak dryline complete with 15-20 mph downslope winds. Max temps were edged higher Tuesday, but could see some respectable cooling by Wednesday as a dry cold front dives south. This front will be tied to a lead trough ejecting from a longwave trough poised to dominate much of the western CONUS by late next week. Barring some conditional PoPs along the trough/dryline Tuesday in our Low Rolling Plains` counties, the more definitive push of deeper moisture should evolve by Thursday and beyond as the upper flow trends more meridional ahead of the digging trough to our west. GEFS members exhibit surprisingly good clustering with this regime which is befitting of high chance PoPs regionally for Friday and Saturday, along with cooler high temps. && .LUB WATCHES/WARNINGS/ADVISORIES... None. && $$ 23/33
Area Forecast Discussion
National Weather Service Portland OR
840 PM PDT Sat Sep 16 2017 .SYNOPSIS...A change in the weather looms Sunday as a series of troughs of low pressure originating in the Bering Sea and Gulf of Alaska move across the Pacific Northwest. A cold front will move across the region Sunday afternoon and evening bringing the first batch of rain. Additional systems behind this front will keep rain chances going through at least mid week. Cooler air will accompany the change in weather, with snow levels lowering in the Cascades. && .SHORT TERM...Tonight through Tuesday...The forecast remains on track this evening so no changes were necessary. Previous discussion (from 302 PM this afternoon) follows...Thermal induced surface trough was over the Willamette Valley Sat afternoon, with a shortwave trough of low pres aloft nearing the coast. A progressive pattern will push the upper trough across this evening, with the surface trough moving east of the Cascades. Surface ridging pushing up behind the trough will bring a weak sw onshore flow tonight. Flow at both surface and aloft becomes more westerly Sun, bringing an increase in moisture in the low to mid levels, and consequently an increase in clouds. This should finally clean out the lingering smoky air mass stuck in the inland valleys. An upper low pressure system originating in the Bering Sea will move down off the BC coast and then inland over southern BC Sun and Mon. This will push a cold front se across the forecast area Sun afternoon and evening. With the onshore flow, models agree on good low and mid level moisture accompanying the front, which looks sufficient to carry likely to categorical pops for Sun afternoon and evening. Once the initial cold front moves through, a cooler air mass moves in for Mon and Tue. Cooling aloft comes in comparatively quickly, resulting in destabilization of the air mass Mon. A series of shortwaves rotating around the digging upper low will keep a threat of showers going through Tue, while continuing westerly low level flow adds an orographic component. GFS forecast soundings suggest sufficient instability for a threat of thunder Mon afternoon, while NAM is less optimistic. With an expectation of plenty of low level clouds, prefer to leave out any threat for thunder from the forecast at this time. Model soundings indicate the unstable layer becoming shallower Mon night and Tue, reflecting a diminished threat for thunder, although a continued low level unstable layer still favorable for showers. Snow levels dropping during the day Mon potentially drop to 6K ft or a little lower. Late Tue there is not great agreement on the track or intensity, but both GFS and EC suggest a surface low approaching the WA coast. Isentropic lift in warm air advection ahead of the low likely spreads onto the coast late in the day Tue, likely turning precipitation more stratiform. As the pattern evolves, from the cold front late Sun, to a showery air mass Mon, to a stratiform rain event late Tue, the prospects for heavier rainfall causing flooding on this summers burn scars in the Cascades increase. With burn scars in steep terrain having a low threshold for handling substantial rainfall, the possibility for needing some sort of flash flood watch or warning specifically for those areas will increase in the coming days. .LONG TERM...No Changes. Previous discussion follows...Tuesday night through Saturday...No Changes. Previous discussion follows...Active weather pattern continues through the week, with another possibly wetter system coming in Tuesday night into Wednesday. The GFS suggests an atmospheric river targeting NW Oregon and SW Washington Tuesday night into Wednesday with precipitable water values around 1" to 1.5" approaching the coast with the warm front Tuesday afternoon. The ECMWF also suggests a good slug of moisture Tuesday night into Wednesday, increasing confidence in heavy rainfall during this period. Rain transitions to showers behind the cold front midday Wednesday, with cool and showery conditions continuing into Thursday. Showers will be tapering off by Friday as a ridge of high pressure builds in for next weekend. Snow levels will drop down to around 5000-6000 ft behind the cold front on Monday, with our first chance for accumulating snow up in the High Cascades. Snow levels look to rise back up to around 7000-8000 ft with the warm front on Tuesday night into Wednesday, but come back down to 5000-6000 ft Wednesday afternoon behind the cold front, for another chance for snow in the High Cascades. High temperatures drop below normal through much of this week with this active, cooler weather pattern. Temps not expected to get back up near normal until next weekend with the ridge building in. -McCoy && .AVIATION...Smoke resulted in areas of MVFR visibilities this evening for the Willamette Valley and Columbia River Gorge with local IFR visibilities. The smoke should improve a little the next few hours. West winds along the coast will slowly make its way inland tonight and eliminate smoke restrictions for the interior valleys. The HRRR smoke forecast suggests that the smoke should clear the Willamette Valley by 4 AM Monday morning. Stratus is starting to fill in along the coast this evening with IFR CIGS at KONP. A deeper marine layer should deepen the stratus and push it inland late tonight through Sunday morning. A cold front will bring rain and gusty south winds to the coast late Sunday morning or early afternoon with MVFR to IFR cigs. The inland stratus should lift in the afternoon as the front nears with rain impacting inland areas late Sunday afternoon. Expect initially VFR conditions with the inland rain with brief MVFR with the front passage in the evening. KPDX AND APPROACHES...Smoke will gradually improve VSBYS this evening. The HRRR model forecasts the smoke will move east of the airport around 9z (1 AM) Sunday. Stratus is likely Sunday morning, but VFR conditions should continue. South winds will increase Sunday with rain expected around 4 PM. MVFR conditions possible Sunday evening with the frontal passage. ~TJ && .MARINE...Light onshore winds across the waters this evening as weak high pressure moves over the waters. The winds will back to the south late tonight and Sunday morning as a cold front approaches the waters. South winds will increase Sunday morning with small craft advisory winds expected Sunday afternoon and evening with the frontal passage. Fresh swell will build sea heights during this time. Onshore winds will follow the front Sunday night and persist through Monday morning. A low pressure off of the B.C. coast moves south Monday afternoon tightening the surface pressure gradient over the waters, and providing another chance for small craft advisory winds Monday afternoon and night. A larger long-period swell builds Monday night with wave heights likely building into the teens. South winds return Tuesday afternoon or night as the next front approaches. The models are coming in better agreement on the parent low and the possibility for Gales Tuesday night into Wednesday. The seas may push into the upper teens Wednesday. ~TJ && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...Small Craft Advisory for winds from noon to 7 PM PDT Sunday for Coastal waters from Cape Shoalwater WA to Florence OR out to 60 NM. && $$ Interact with us via social media: This discussion is for Northwest Oregon and Southwest Washington from the Cascade crest to 60 nautical miles offshore. This area is commonly referred to as the forecast area.