Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/07/18

Area Forecast Discussion...UPDATED
National Weather Service Albuquerque NM
542 PM MDT Thu Sep 6 2018 .AVIATION... 00Z TAF CYCLE VFR conditions are currently in place over most of northern and central New Mexico early this evening, the exception being where stronger showers and storms are producing temporary downpours with lowered ceilings/visibility. Showers and thunderstorms are expected to continue increasing across central New Mexico through the evening with low confidence on shower characteristics after midnight. High resolution forecast models indicate showers and storms will slowly translate eastward into the eastern half of the state through dawn Friday with some scattered areas of low clouds and MVFR/IFR ceilings surrounding. Drier air is expected to infiltrate western New Mexico on Friday, limiting afternoon storm chances while scattered to numerous storms remain possible in the eastern half. 52 && .PREV DISCUSSION...315 PM MDT Thu Sep 6 2018... .SYNOPSIS... Scattered to occasionally numerous showers and thunderstorms, some with locally heavy rain, are expected tonight through Friday. Drier air and upper level high pressure will work into western New Mexico later Friday and over the state Saturday and Sunday, reducing the number and areal coverage of showers and thunderstorms. Over the weekend any showers and storms that develop may be focused over and near the central mountain chain and northeast New Mexico. High temperatures will be cooler than normal through Saturday before warming to above average next week. && .DISCUSSION... A quiet afternoon so far on the radar with storms mostly along the boundary of thinner/thicker cloud cover, and a few over the northern higher terrain. Models again not in very good agreement even during the next 6-12 hours. Latest HRRR indicates convection diminishing by midnight, but has what appears a weak surface boundary pushing into northeast New Mexico late this evening/after midnight, similar to the NAM12. However, the NAM12 develops some precipitation along and behind this boundary as it sags into the northeast and east central plains late this evening and overnight while the HRRR is dry. Slanted the pop forecast towards the NAM12, but confidence isn`t supremely high. Warming and drying trend from the west Friday and into the weekend is still in the forecast. Models do suggest a disturbance crossing north central and northeast New Mexico Saturday will produce some meager precipitation. The disturbance forecast to clip the same part of New Mexico Sunday/Sunday night is now forecast to be more vigorous, and may generate showers and storms over a larger portion of the north central and northeast, and may even spread into the east central Sunday night. Made some adjustments to the pop/wx grids for this. Early to mid next week, models indicate the upper ridge over the Southwest U.S. may be flatter, then is shunted to the east of New Mexico. The ECMWF has fallen into line with this idea, so there may be some moisture that leaks into western and central New Mexico mid to late next week. && .FIRE WEATHER... Showers and thunderstorms have developed across western NM where clouds cleared and more destabilization has occurred after last nights rainfall. As clouds across central and eastern NM continue to diminish this afternoon, additional thunderstorm development will be possible, though overall, it will not be as widespread as yesterday. Good to excellent RH recoveries are likely again tonight. On Friday, the upper level high will begin to nudge eastward into western NM. This will limit convection across the west, though eastern NM will remain active. The upper high will continue to expand eastward over the weekend, and drier air will continue to filter in behind it. This will lower minimum humidity values each day, with sub-15% humidities likely across the northwest plateau by Sunday. A few storms will remain possible both days, though there will be a significant downtick. Nonetheless, a weak shortwave will clip NE NM on Sunday which may spark a few strong storms there. Monday will be very similar to Sunday, and by Tuesday, the upper level ridge will be centered over NM. Thereafter, models are suggesting the upper high will elongate from NM northeast toward the Great Lakes as a trough moves into the western CONUS. Some modest moisture may creep northward allowing for a slight uptick in thunderstorm coverage toward the end of next week. Poor ventilation rates remain likely across eastern NM and portions of the Rio Grande Valley Friday and Saturday. 34 && .AVIATION... 18Z TAF CYCLE MVFR to IFR cigs continue across portions of eastern NM late this morning, though will lift throughout the afternoon. Showers and thunderstorms are expected again this aftn, initially over the high terrain before spreading east or southeast onto lower elevations. MVFR cigs/vsbys are possible with heavy rain producing thunderstorms. Most storms will diminish by 03Z, though any lingering storms will favor eastern NM. Clouds should diminish or clear out overnight across western NM but another round of MVFR/IFR cigs are possible across portions of eastern NM overnight, especially across NE NM. 34 && .ABQ WATCHES/WARNINGS/ADVISORIES... None. && $$
Area Forecast Discussion
National Weather Service Bismarck ND
935 PM CDT Thu Sep 6 2018 .UPDATE... Issued at 925 PM CDT Thu Sep 6 2018 Severe convection over eastern Stark and western Morton counties has dissipated. A few thunderstorms remain over south central ND for the next couple hours but as convective inhibition increases and cells move away from the area of greatest instability west of the Missouri, expect a downward trend in intensity. We did extend some slight chance to chance pops from southwest/south central northeast into the James River valley through the late evening. Otherwise no significant changes to the forecast. Scattered convection from the Turtle Mountains into northeast ND will gradually slide southward tonight and may still clip the JMS area with general thunder late tonight. UPDATE Issued at 618 PM CDT Thu Sep 6 2018 Convection in the north central has moved out of the forecast area. Additional convection is now developing over southwest into south central ND. Good instability but and marginal shear in this area could support a few strong to severe storms early this evening with the biggest threat being hail to an inch or so. Updated pops this evening to the convection. Otherwise no significant changes to the going forecast. && .SHORT TERM...(This afternoon through Friday) Issued at 157 PM CDT Thu Sep 6 2018 Chances for showers and thunderstorms north and then into east central North Dakota tonight highlight the short term period. Strong to isolated severe thunderstorms remain a possibility across the north through this evening. Latest water vapor imagery shows a mid level/700mb shortwave now moving into Roosevelt County, MT, which is forecast to shift across northern North Dakota this evening. Latest SPC mesoanalysis still advertises 1000 J/Kg of MU CAPE/most unstable CAPE along with Effective Bulk Shear of 35kt, which is sufficient for strong to isolated severe thunderstorms. Latest radar indicates thunderstorms from Upham to Rugby. Will maintain strong to isolated severe thunderstorm wording within the HWO and weather story. The threat for thunderstorms will sag south tonight, from the Turtle Mountains this evening into the northern James River Valley. This is right along a developing warm frontal boundary with a persistent low level southerly wind flow and associated moisture advection. Thus expect elevated convection as the surface decouples this evening per RAP BUFKIT KJMS sounding. A lack of shortwaves through most of Friday will allow for a dry and warm day south, while the warm front remains nearly stationary until late afternoon/early evening before moving towards the northern border. Highs Friday will be in the 80s; as compared to the north where the warm front will not have quite made it through, and highs there will be in the lower 70s. Additional shortwaves begin migrating into western North Dakota after 00z Saturday, which leads into the Long Term Discussion beginning Friday night below. .LONG TERM...(Friday night through Wednesday) Issued at 157 PM CDT Thu Sep 6 2018 Expect elevated showers and thunderstroms Friday night north, located along and north of the warm front as it shifts into southern Canada. For Saturday, a cold front will move into western North Dakota between 00z and 03z Sunday, then through central ND by around daybreak Sunday, before stalling over the James River Valley. A secondary cold front pushes the initial/stalled front east Sunday night. This scenario sets up showers and thunderstorms across western North Dakota Saturday afternoon and evening, then central ND Saturday night. It would appear the threat for showers and thunderstorms continues Sunday and Sunday night in the James River Valley due to the cold front slowing and stalling Sunday morning. Overall a weak CAPE/Shear environment dominates most of the convection Saturday and Saturday night, then per GFS, increases over the James River Valley late Sunday afternoon/evening. Although strong to possible severe thunderstorms exists with the entire cold frontal movement from west to east late Saturday afternoon through Sunday evening; the favored area for severe weather as of now would be the James River Valley during Sunday afternoon/evening. The secondary cold front sweeps through Sunday night with cooler and drier air arriving Monday. Southwest flow aloft continues through most of next week, which keeps mostly an active pattern in place. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 925 PM CDT Thu Sep 6 2018 VFR conditions expected this forecast period. Convection is firing east of KDIK and could move into KBIS aerodrome this evening. Added a period of VCTS at KBIS. Convection in the north central to northeast could also drop south to near KJMS. Elsewhere convection is not expected. Added a mention of LLWS at KBIS 09-14 UTC. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...TWH SHORT TERM...KS LONG TERM...KS AVIATION...TWH
Area Forecast Discussion
National Weather Service Denver/Boulder CO
758 PM MDT Thu Sep 6 2018 .UPDATE... Issued at 757 PM MDT Thu Sep 6 2018 Showers and thunderstorms have moved south over the Palmer Divide of over the eastern plains. Removed the mention for showers and storms for most of the Urban Corridor for tonight. Skies will continue to clear this evening, leading to good radiational cooling and fog. Expect many areas to see fog by sunrise with visibility falling below a quarter mile in places. && .SHORT TERM...(This evening through Friday) Issued at 315 PM MDT Thu Sep 6 2018 Interaction between a weak upper-level weather disturbance and a moist, marginally unstable atmosphere will result in scattered to numerous showers and thunderstorms over and along the Front Range through mid-evening tonight. The strongest storms are expected to form along a Denver vorticity convergence zone (DVCZ) which has remained nearly stationary from northern Teller County to south central Weld County. Convection has quickly developed along this boundary within the past hour with multiple CBs now evident on GOES-16 visible sat imagery. RAP and HRRR presently indicate a narrow ribbon of relatively high MLCAPE, upwards of a 1000 J/Kg, over the southern end of this boundary. The band of t-storms presently moving off the Front Range should interact with the convective updrafts along the DVCZ within the next hour to potentially produce even stronger and slower moving storms cells capable of 1-2 inch per hour rainfall rates. Cells roughly south of I-70 could possibly produce 1.5-2.5 inches in a short period, potentially causing flash flooding. This convection is expected to drift east-southeast through the evening ending up in Lincoln County by midnight, if not before. Later tonight, the influx of drier mid-level air on the back side of the exiting upper trough will resulting in clearing. However, this clearing will allow radiational cooling to form areas of fog on the plains by dawn. Areas in the thicker fog could see visibilities as low as a quarter mile, and possibly a few sprinkles. Friday looks drier and slightly warmer on the back side of the departing trough with the flow aloft turning northwesterly. However, there will be enough moisture around to combine with daytime heating to produce widely scattered late day t-storms mostly over the higher elevations. Temperatures during the next 24 hour will remain a few degs F below average for the date. .LONG TERM...(Friday night through Thursday) Issued at 315 PM MDT Thu Sep 6 2018 The main trend through the weekend and middle of next week is for a warming and drying for Colorado. Initially, Broad high pressure aloft will be building into Colorado for the weekend with a light to moderate west to northwest flow aloft. There will still be enough moisture and limited instability for isolated late day showers and thunderstorms. By early next week an upper trof will develop over the Pacific Northwest which will result in a drier, southwest flow over Colorado. This will result in even drier and warmer conditions, especially from next Tuesday through Thursday. Extended guidance through this period is showing temperatures back close to 90s on the plains with little if any storms for any of the area. 700mb temperatures climb into the +14 to +17c next week which support these very warm temperatures. Pretty typical conditions for a normally dry September, but temperatures will be above normal for this time of year. Precipitable water trends will be down to around a half of an inch or less during the dry period. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 757 PM MDT Thu Sep 6 2018 Showers and thunderstorms have moved southeast of the Denver area, ending the chance for precipitation. Added a tempo for quarter mile visibility and fog late tonight and Friday morning, 11-14Z. With many short term models showing fog, later forecasts may need to keep in the forecast longer. Expect low clouds to linger until around 18Z once the fog lifts. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Meier SHORT TERM...Danielson LONG TERM...Entrekin AVIATION...Meier
Area Forecast Discussion
National Weather Service Billings MT
830 PM MDT Thu Sep 6 2018 .UPDATE... No update for the inherited short term forecast, with isolated showers in the west and extreme southeast. AAG && .SHORT TERM...valid for Fri and Sat... Low amplitude ridge exists over the region, with a weak shortwave approaching from central ID. Some convection has developed over our mountains but nothing has spread across the foothills yet. Latest HRRR runs have trended weaker w/ thunderstorm activity over the next six hours, and this is in line w/ this morning`s HREF. That being said, dew points are seasonably high and thunderstorms developed over the high terrain sooner than models had suggested. So, feel some activity will spread off our western foothills by this evening as ascent from shortwave moves into south central MT. Erratic/gusty winds are possible near any storms, so keep a heads up if you have outdoor plans this evening. Another weaker shortwave will move into the area Friday. Timing of this energy is such that we`ll see drier west winds across our western areas by afternoon (though isold storms are expected over the mountains and foothills), and better chance of storms will be in our east where surface trof meets southeasterly flow and higher moisture. Stronger shortwave arrives Saturday bringing a better chance of showers and thunderstorms. Initial PV axis actually reaches our area early and should see some morning showers around. Shear is limited but could see a stronger storm in our east by Saturday afternoon. Looks like scattered activity for western/central areas by evening, with increasing pwats and what should be wetter storms overall. Scattered pops are warranted for Saturday evening, with some activity persisting across our east overnight as a Pacific front moves thru the cwa. Temperatures will remain above normal the next two days. Some locations will see 90 degrees Friday. Saturday should be just slightly cooler ahead of the Saturday night frontal passage. JKL .LONG TERM...valid for Sun...Mon...Tue...Wed...Thu... Models are in good agreement to end the week through the middle of next week but diverge toward late next week. A zonal flow pattern will be in place over the forecast area Sunday and Monday. Some slight ridging builds Monday in response to an upper low and trough approaching the Pacific northwest. Models keep this upper low fairly stationary with a slight movement south along the Washington coast through Wednesday before moving inland Thursday with a second low approaching the Pacific northwest coast by Thursday. This will result in a southwest flow aloft across our forecast area Tuesday into Thursday. Pieces of energy will eject from this upper low and get entrained within the flow aloft. However, models take this energy across north central Montana and keep it out of our area with the exception of our far western edge of our forecast area from Park to Wheatland Counties. The forecast overall looks to be mainly dry for most areas with temperatures around normal for this time of year, with normal right now being 78 degrees. Hooley && .AVIATION... VFR flight conditions will prevail through Friday. An isolated thunderstorm will remain possible until 06Z, possibly bringing erratic/gusty winds to KLVM/K3HT/KBIL. JKL/Reimer && .PRELIMINARY POINT TEMP/POPS... Fri Sat Sun Mon Tue Wed Thu ----------------------------------------------------------- BIL 057/088 059/084 055/076 050/084 051/080 050/076 050/076 20/U 12/T 31/B 10/U 00/U 11/U 11/B LVM 049/088 052/083 047/074 042/082 043/079 043/075 043/074 21/U 13/T 31/B 10/U 00/U 11/B 11/B HDN 053/090 053/085 053/076 048/085 049/082 048/079 048/079 20/U 12/T 31/B 10/U 00/U 01/U 11/B MLS 057/091 059/087 056/077 051/085 053/083 051/078 052/077 00/B 11/B 21/B 11/U 00/U 01/B 11/B 4BQ 056/090 058/088 053/079 050/085 053/084 051/081 050/078 10/U 21/B 21/B 10/U 00/U 00/U 00/U BHK 054/089 056/086 053/078 048/081 052/083 048/078 049/075 20/U 22/T 21/B 00/U 00/U 00/B 00/U SHR 050/090 052/085 049/075 046/084 047/083 046/077 047/079 21/U 12/T 31/U 10/U 00/U 00/U 00/U && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...None. WY...None. && $$
Area Forecast Discussion
National Weather Service Grand Forks ND
959 PM CDT Thu Sep 6 2018 .UPDATE... Issued at 957 PM CDT Thu Sep 6 2018 850-700 mb frontogensis continues in band from Cando to Thief River Falls this evening and region is area of surface confluence with high to the north and northeast winds and southeast winds with low to the southwest. Mid level moisture will continue near this frontogenesis zone along with 850-700 mb warm advection. Thus would expect continued shower and t-storm activity in this band the next several hours though it should begin to wane later tonight. Also a few t-storms/showers near Bismarck is moving east and may hold together into parts of SE ND later tonight but coverage is small and not in a favorable mid level frontogenesis region. Continued to have higher pops Cando-GFK-TVF-BJI til past 06z. && .SHORT TERM...(This afternoon through Friday) Issued at 339 PM CDT Thu Sep 6 2018 A stalled frontal zone/conference zone just northwest of DVL has acted as focus for thunderstorm initiation with WAA riding along this baroclinic zone aloft. There have been some surprisingly robust (however marginal) updrafts despite limited instability advertised by RAP analysis (MU CAPE 500 J/KG). Effective shear near 30kt could be helping support the elevated (pulsy) updrafts, with marginal severe hail risk. Trend should be for any strong to marginally severe storms to decrease in intensity as they spread eastward of instability axis. Strong signal on CAMs supports moderate shower activity at times along/north of Highway 2, with redevelopment possible into southeast ND late tonight. So, while there is a substantial dry layer below 800 MB, there may be enough instability/forcing to support higher PoPs and I trended forecast in this direction. Focus for any redevelop should tend to be due to WAA withing SE flow overriding stalled frontal zone through the night, which would match trend for activity to redevelop in central ND toward SE ND. By Friday most activity should weaken (though a few sprinkles or light showers still can`t be ruled out through the afternoon). Regarding temperatures: Moderation of the air mass over our region has already been underway. Cloud cover tonight will also limit radiation cooling, so overnight lows should generally remain 50F or warmer. Dependent on clearing Fri we should see highs in the middle 70s (a little cooler where cloud cover holds on). .LONG TERM...(Friday night through Thursday) Issued at 339 PM CDT Thu Sep 6 2018 00Z Sat - 00Z Mon Warm advection precip is forecast for Fri night and early Sat mainly north of Hwy 2 as upper level ridge ridge shifts east and low level jet responds. Winds were increased a bit throughout this entire period. Short wave over the eastern Pacific will move into the Northern Plains by Sun and bring a threat for thunderstorms Sat night into Sun. Sun night - Thu Long wave pattern goes from zonal to more of a southwest flow aloft. Should make for a more active weather pattern. Split flow aloft consolidates. Long wave trough off the West Coast will sharpen through the period. Long wave trough remains over northern Canada. Mid level cap and 700 hpa theta-e axis will shift east across the area Tue. Storms will be possible north of the cap is expected for next Tue. Similar event is expected for Wed night but farther north in the northern Red River Valley. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 703 PM CDT Thu Sep 6 2018 Cloud bases remain quite high in the 6-10k agl range. So VFR in that aspect and also vsbys. But area of rain and a few storms will affect esp GFK area thru the evening. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. && $$ UPDATE...Riddle SHORT TERM...DJR LONG TERM...JH AVIATION...Riddle
National Weather Service Jackson KY
1016 PM EDT Thu Sep 6 2018 .UPDATE... Issued at 949 PM EDT THU SEP 6 2018 Convection is showing an overall decline, but is slower to fade than was expected. The HRRR suggests that the thunderstorms regenerating in southeast KY presently will also fade away over the next few hours. In the mean time, have extended the mention of rain in the forecast for a while longer. && .SHORT TERM...(This evening through Friday night) Issued at 300 PM EDT THU SEP 6 2018 The remnants of the tropical system reside over Arkansas this afternoon. Per water vapor imagery. An area of deformation extends along the spine of the Appalachians. This has led to very little shear and very slow shower and storm movement today. The lack of shear has really limited stronger activity today and thus, we haven`t had a big issue with heavy rain today. Will maintain a small chance of shower and a few storms into the evening, but once we lose instability, we should see everything die down much like the past several evenings. This will lead to some more river valley fog tonight. Could see locally dense fog down in the southwest areas where the rain has fallen today. By tomorrow, a cold front will stall just north of the Ohio river. This should focus the best shower and storm chances to our north. However, enough moisture and instability remains that we should see another round of isolated shower and storm activity. This activity should die off once more as we lose instability tomorrow evening with another night of valley fog for Friday night. As it stands right now, showers and storms should erode enough in time for Friday night festivities. .LONG TERM...(Saturday through Thursday) Issued at 425 PM EDT THU SEP 6 2018 No significant changes to the extended. Models continue to exhibit good agreement in solutions with respect to the overall pattern and sequence of events. Remnants of Gordan and the potential for heavy rain continue to be the focus of the forecast. In general models have trended slightly slower with solutions and sequence of events through the extended. Gordon will phase with an approaching shortwave trough moving eastward from the Plains Friday night through Saturday. Gordon should complete the process of transitioning into a subtropical system by Saturday night and then make a more aggressive move northeast through the Midwest and Great Lakes Region by the start of the new week. Additional shortwave energy moving in from the west will tend to reinforce some of the troughiness across the Ohio and Tenn Valley and may slow progress of a surface frontal boundary through eastern Kentucky until early to mid-week, or the Tue-Wed time frame. The ECMWF, Canadian, GFS, and Parallel GFS (FV3) are showing signs of narrowing on solutions with respect to Florence, which now bring the system towards the Mid-Atlantic region by Thursday. Three of the four solutions bring Florence at least briefly on shore somewhere between North Carolina and Long Island by the end of the period or just beyond the extended window. Only the FV3 keeps Florence off shore (just). Sensible weather features an unsettled weather pattern with the potential of heavy rain across at least a portion of our forecast area. Areas most likely at threat will be roughly along and north of a line from Mount Vernon to Sandy Hook, where between 2 and 3.5 inches of rainfall will be possible. PWATs will climb to between 1.7 and 2 inches with a surface frontal zone across the region providing a focus for convection. This could set the stage for repeated rounds of showers and thunderstorms for our more northwestern zones. With respect to timing, Saturday night through Monday appears to be the main window of concern, where the bulk of rainfall could take place. Some uncertainty still exists in the exact track, timing, and evolution of this system through the region. In addition, with the main event still 5th period or further out, decided to reissue and fine tune the ESF for now. However, would not be surprised if a watch were issued within the next forecast cycle or two. Again, at this time areas most likely to be affected are our northeastern zones. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) ISSUED AT 916 PM EDT THU SEP 6 2018 Scattered showers and thunderstorms were ongoing over the region this evening, but the overall trend will be for a decrease in activity, with most of it expected to fade away by around 05Z. Generally quiet weather is then expected until more showers and thunderstorms develop during the day on Friday. Any of the thunderstorms could bring IFR or worse conditions. At this time, KSYM is the only TAF site where there is enough confidence to make a mention of VCTS in the forecast on Friday. In addition to the precip, fog is again expected in valleys tonight into Friday morning. It may spread beyond valleys, especially where significant rain occurred on Thursday evening. In the TAFs, have allowed visibility restrictions to some extent at all TAF sites, but confidence is low. Outside of fog and precip, mainly VFR conditions are expected. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...HAL SHORT TERM...KAS LONG TERM...RAY AVIATION...HAL