Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/19/20

Area Forecast Discussion
National Weather Service Bismarck ND
906 PM CDT Mon May 18 2020 .UPDATE... Issued at 854 PM CDT Mon May 18 2020 Will allow the Wind Advisory to expire. Winds at Williston have diminished to around 20 mph with gusts to 35 mph (below advisory criteria) at 9 PM CST and are the strongest in western ND this hour. It will remain breezy through the night across western and central ND, but winds will remain below advisory criteria. We bumped up sky cover a little, otherwise no significant changes for the late evening update. UPDATE Issued at 639 PM CDT Mon May 18 2020 Current forecast looks in line so only a few adjustments to sky increase sky cover a bit with thicker cirrus moving over the forecast area. A strong pressure gradient remains over the west and is pushing into the central. The current advisory in the west runs through 8 PM MDT and that looks reasonable. Winds from the Highway 83 corridor west to the current advisory are right near advisory criteria, but we expect these winds to diminish here shortly. Everyone will see breezy winds overnight, but below advisory criteria. && .SHORT TERM...(This evening through Tuesday night) Issued at 251 PM CDT Mon May 18 2020 Warm and breezy conditions are expected on Tuesday with highs nearing 90 degrees F in the west/southwest. There is a very slight chance of thunderstorms in the far west Tuesday evening, with the potential for severe hail if one does form. Aloft, a deep trough was situated over the western US coast with 50 kt 500mb flow extending from the Great Basin through the Northern Rockies. A ridge was parked over the central High Plains through the Upper Mississippi Valley upstream of a closed low centered over Illinois. At the surface a strong pressure gradient was draped north- south through the western Dakotas as pressure falls were ongoing in eastern Montana. Within this surface pressure gradient, southerly winds gusting to around 50 mph were reported this afternoon in far western North Dakota. Though diminished somewhat, breezy winds will continue overnight tonight and tomorrow as the pressure gradient slowly shifts east. Low-mid level flow will be slightly so surface winds shouldn`t be as strong, but still in the 20 to near 30 mph range Tuesday afternoon. Very warm low level temperatures begin to move over the area as well with MOS guidance consistent in producing surface temperatures in the upper 80s to near 90 in the far west. 70s to low 80s can be expected elsewhere. Tuesday afternoon and evening, ongoing southerly low level flow is expected to advect dew points in the 50s to around 60 in the southwest/west portions of the state. Coincident with the warming 850-700mb air mass and the development of a potent elevated mixed layer, a capped atmosphere with increasing MUCAPE will be in place by Tuesday evening. Though the 12Z GFS/NAM produce a subtle impulse out of the main trough in the evening, there is little evidence in forecast soundings of enough low to mid level moistening to overcome the capping inversion. On the conditional potential that a thunderstorm does form Tuesday evening, lapse rates and deep layer flow may be enough to produce a severe hail threat. .LONG TERM...(Wednesday through Monday) Issued at 251 PM CDT Mon May 18 2020 Chances for showers and thunderstorms increase Wednesday afternoon/evening in far western North Dakota with a potential for severe weather and heavy rainfall. Generally the best chances for thunderstorms will be further west into Montana. Almost daily chances for showers and thunderstorm fill out the rest of the long term forecast. Wednesday, the main trough is forecast to track northeastward out of the Intermountain West and the Northern Rockies. In response, surface cyclogenesis will occur over eastern Montana, Wyoming, and the western Dakotas. With a continued poleward flux of boundary layer moisture expected along the surface trough and ongoing mid- level lapse rate advection, a corridor of 1000-2000 J/kg of MLCAPE is expected to develop Wednesday afternoon. Greatest instability and forcing for ascent should be focused generally along and in the near- vicinity of the surface trough axis and frontal boundary, making the potential of severe convection in North Dakota uncertain as 12Z guidance keeps the surface trough axis in eastern Montana through most of the night. Additionally, deep layer shear will be in question with the 12Z GFS/ECMWF producing only 25-35 kts of effective bulk shear along our west as the bulk of the better mid- level flow should be kept further west. In either scenario, mostly unidirectional southerly flow along the frontal boundary should promote upscale growth or messy convective modes Wednesday evening...further decreasing confidence in a more widespread severe potential. At the time it looks as if the the greatest severe potential will be for the very far west portions of the state on the condition of initially discrete storms in a modest but adequate supercell environment. This applies as well to the general eastward extent of precipitation in the forecast with best chances kept to the west. Lastly, there will be the additional threat of very heavy rainfall with these potential thunderstorms given anomalously high precipitable water values in the west shown on NAEFS guidance (in the 90th to near climatological max). Another shortwave enters the broad trough from the northwest coast on Thursday, keeping a mean troughing pattern over the west/northwest CONUS through the rest of the week. Embedded perturbations in southwest flow over the Northern Plains keeps persistent daily chances for showers/thunderstorms for the remainder of the forecast period with somewhat cooler but seasonable temperatures expected. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 854 PM CDT Mon May 18 2020 LLWS was added to KMOT and KBIS around the 06-12 UTC timeframe. Otherwise VFR conditions expected through the forecast period with only mid and high clouds and a moderate to strong southeast flow. 00Z RAP soundings continue to indicate winds around 50 knots at Minot and Bismarck after midnight. No changes to current TAFs. Previous Discussion... The 19 May 00 UTC Bismarck sounding indicates strong southeast flow aloft. This seems to match up better with the current RAP guidance better than the NAM or GFS. The latest RAP forecast soundings show winds aloft increase tonight to around 50 knots out of the south southeast at Bismarck and Minot after midnight. Even though surface winds are nearly the same direction, this still gives 30 to 40 knots of shear. We did allow for surface winds to drop off to around 15 knots. If surface winds do not drop off, we probably won`t have enough shear, just some turbulence through 2000 ft. Will continue to monitor this evening for the 06Z TAFS. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...TWH SHORT TERM...AE LONG TERM...AE AVIATION...TWH
Area Forecast Discussion
National Weather Service Denver/Boulder CO
812 PM MDT Mon May 18 2020 .UPDATE... Issued at 812 PM MDT Mon May 18 2020 Some cumulus congestus clouds formed to the southwest of Denver early this evening. Radar didn`t pick up much for echos. This likely had a little virga and localized gusty winds. The activity will decrease in the next couple hours. Gusty southeast winds to 40 mph are expected to linger through the evening and then decrease across the eastern plains. Enough wind should prevail overnight to produce mild overnight lows. Made a few tweaks to winds and sky coverage to line up with current conditions, otherwise no other changes were made to the forecast. && .SHORT TERM...(This evening through Tuesday) Issued at 328 PM MDT Mon May 18 2020 Temperatures have warmed quickly this afternoon with DIA reaching 88 by 245pm. The HRRR still produces showers over the Denver metro this evening but considering the lack of almost any cloud development over the mountains and foothills this afternoon, I doubt those showers will occur. Therefore, PoPs were kept below 10 percent this evening. Tonight, there could be some hazy conditions as moisture creeps in from the east but fog is not expected to develop. Some low clouds are possible mainly across the far eastern plains closer to Kansas and Nebraska. A large trough continues pushing eastward toward Colorado on Tuesday although the strongest mid to upper level winds will not enter the state until Wednesday. With 700 mb temperatures approaching 16-17 degrees C, high temperatures will race toward 90 degrees F over the Denver metro and the South Platte River Valley. Current, the forecast is 89 at DIA as the presence of cloud cover and scattered showers and storms may keep the temperature down just a tad. However, the record high of 90 degrees in Denver could be tied or broken. High lapse rates with near dry adiabatic temperatures to around 500 mb will lead to high-based showers and storms developing in the afternoon. Considering the inverted-V soundings all the way up to 500 mb, these showers and storms will likely produce dry microbursts with strong to severe wind gusts up to 60 mph. These showers and storms could produce small hail which should remain below severe limits across our forecast area. The only exception would be across the northern half of Weld and Larimer Counties as better instability will exist there. The dry and windy conditions will create critical fire danger as well and that is discussed in the fire weather section below. .LONG TERM...(Tuesday night through Monday) Issued at 328 PM MDT Mon May 18 2020 Warm and active weather will continue on Wednesday as a high amplitude upper air pattern remains over the western United States. Moderate southwesterly flow aloft will continue downstream from an upper low over Idaho. At the surface, a low pressure trough along the foothills will help to induce southeasterly low level flow which will be drawing gulf moisture into the region. Daytime heating and wind shear profiles should be sufficient for strong afternoon thunderstorms to develop on the plains. A weak cold front moving over the plains Thursday morning, in the wake of Wednesday evening`s convection should be enough to reduce the threat of thunderstorms as afternoon highs only reach the lower 70s. Heading into the weekend, temperatures are expected to warm again to slightly warmer than normal. Afternoon instability each day should allow for widely scattered thunderstorm activity to develop. The latter half of the weekend will be cooler again, but medium range models show a variety of solutions for the start of next week, so no more details can be given now. Most precipitation over the next several days should be on the plains, so it should have little impact in the ongoing melt-out of the winter snowpack. Mountain streams will see increased flows, but channels will have plenty of capacity to handle the flow. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 812 PM MDT Mon May 18 2020 VFR conditions will continue through Tuesday. Winds will stay more south to southeast compared to drainage tonight. Gusts to 30 knots will continue through 05Z before decreasing. Elevated showers and storms will be more numerous tomorrow afternoon. With inverted-V soundings that reach up to near 500mb, these showers and storms will be capable of producing very strong to potentially severe wind gusts. Ceilings and visibilities should not be reduced much in these showers and storms. Expect this convection to occur after 21Z Tuesday. && .FIRE WEATHER... Issued at 328 PM MDT Mon May 18 2020 Moderate to strong south-southwesterly flow will be over the forecast area on Tuesday with surface wind gusts as high as 35-40 mph. Relative humidities will drop to the low teens across South Park, the southern Front Range Foothills, the Palmer Divide, and the Denver metro. This combination of dry and windy conditions will lead to critical fire weather conditions across these areas. In addition, showers and storms could create strong to severe wind gusts up to 60 mph with very little rainfall which will increase the fire danger further. Overall, these conditions are somewhat marginal to issue a Red Flag Warning but the fact that a fire started in the southern foothills today has lead me to issues one. The Red Flag Warning will be in effect from noon to 8pm tomorrow for South Park, the southern Front Range foothills, and the Palmer Divide. A Red Flag Warning was not issued over the Denver metro since fuels are in green-up and not conducive for rapid fire growth. && .BOU WATCHES/WARNINGS/ADVISORIES... Red Flag Warning from noon to 8 PM MDT Tuesday for COZ214-216- 241. && $$ UPDATE...Meier SHORT TERM...Danielson LONG TERM...Dankers AVIATION...Meier FIRE WEATHER...Danielson
Area Forecast Discussion
National Weather Service Duluth MN
1048 PM CDT Mon May 18 2020 .SHORT TERM...(This evening through Tuesday night) Issued at 249 PM CDT Mon May 18 2020 Windy conditions with critical fire weather across portions of northeast Minnesota this afternoon and evening highlight the short term forecast. See the fire weather section below for details on critical fire weather conditions that will continue for portions of northeast Minnesota into early this evening. Strong northeast to easterly winds across the Northland will continue into the early evening north of deep low pressure across Illinois. Momentum transfer has been very efficient thus far this afternoon from the Brainerd and Walker areas northeast into the Twin Ports and the Iron Range with peak gusts of 30-40kts. 17Z RAP soundings favor a very slow decrease in the mixed layer momentum through the afternoon and early evening, thus, peak gusts over 30kts are likely to continue into the early evening. On Tuesday, a surface ridge axis will support east to southeast surface winds across the Northland favoring highs in the 50s and 60s near Lake Superior with onshore flow, and 70s elsewhere far enough from the influence of the lake with plentiful sunshine. .LONG TERM...(Wednesday through Monday) Issued at 249 PM CDT Mon May 18 2020 A warming trend through the extended with chances for thunderstorms late this week and into the weekend highlight the extended forecast. The 12 UTC global suite favors an upper level ridge building across the central CONUS into mid week, transitioning to a high over low blocking pattern, and eventual southwest flow aloft across the Upper Midwest late this weekend and weekend. This all favors a warming trend to widespread highs in the 70s, and maybe a few 80s, this week with increasing chances for thunderstorms Friday and into the weekend with impulses likely to be embedded in southwest flow aloft. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 655 PM CDT Mon May 18 2020 As high pressure moves into the region, mostly clear skies and VFR conditions will continue this evening and into Tuesday. Winds will be breezy at the surface this evening with LLWS about 2000 feet agl possible at HYR in the overnight hours. There is also a chance for LLWS near DLH and BRD from midnight to 7 AM CDT; however, there was quite a bit of variation between models of the wind shear strength and timing. Thus decided not to add LLWS to DLH and BRD yet and see how winds progress over this evening. High pressure continues on Tuesday with VFR conditions and west/northwesterly winds 10 to 15 knots with stronger winds near DLH. && .MARINE... Issued at 1035 PM CDT Mon May 18 2020 Breezy conditions are again likely across western Lake Superior on Tuesday before winds begin to decrease on Wednesday. As high pressure continues to move into the region, winds and waves will diminish overnight before increasing again early Tuesday morning. Northeasterly winds 10 to 20 knots with gusts up to 25 knots, and waves 3 to 5 feet will affect the North Shore from Grand Marais to the Twin Ports, as well as the South Shore. A Small Craft Advisory is in effect from 8 AM to 9 PM CDT on Tuesday. Depending on how strong the winds get the Advisory might need to be extended further towards Grand Portage Monday afternoon. By Wednesday, winds begin to calm with northeasterly winds 5 to 10 knots. && .FIRE WEATHER... Issued at 249 PM CDT Mon May 18 2020 A Red Flag Warning remains in effect until 7 PM CDT from the Walker and Brainerd areas northeast through the Iron Range of central St. Louis county. Strong easterly winds sustained at 15 to 20 mph with gusts to near 30 mph at times, relative humidity of 20 to 25 percent, and high temperatures in the 70s will combine with dry fuels to create critical fire weather conditions this afternoon and early evening. && .PRELIMINARY POINT TEMPS/POPS... DLH 43 61 44 69 / 0 0 0 0 INL 43 77 49 79 / 0 0 0 0 BRD 44 70 52 76 / 0 0 0 0 HYR 46 73 49 78 / 0 0 0 0 ASX 41 62 44 73 / 0 0 0 0 && .DLH WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. LS...Small Craft Advisory from 8 AM to 9 PM CDT Tuesday for LSZ121- 141>148. && $$ SHORT TERM...PA LONG TERM...PA AVIATION...KL/BJH FIRE WEATHER...PA MARINE...KL/BJH
Area Forecast Discussion
National Weather Service North Platte NE
815 PM CDT Mon May 18 2020 .UPDATE... Issued at 815 PM CDT Mon May 18 2020 Sky cover was increased tonight after midnight especially across central and eastern areas. The latest RAP and NAM models are forecasting stratus to develop later tonight and last until mid morning Tuesday. The remainder of the forecast remains unchanged. && .SHORT TERM...(This evening through Tuesday night) Issued at 255 PM CDT Mon May 18 2020 Ridging and mid-level height rises continue to dominate the weather pattern across central and western Nebraska as quiet weather continues towards mid-week. Morning stratus across much of central Nebraska is starting to dissipate as low-level winds veer and warm- air advection increases across the area. Winds will remain generally out of the south through the next few days, helping to advect better moisture in the area that`ll set the stage for periodic rain and thunderstorm chances, mainly covered in the Long Term discussion. For the rest of Monday, dry conditions are expected as the area falls between the troughing in the west and east. Temperatures will generally remain at or above normal for mid-May standards with lows falling into the 40s and 50s, or generally around 5 degrees above climatological lows. Winds off the surface will increase tonight as mid-level heights compress and a modest low-level jet develops. Strongest winds will remain west of Highway 83 where occasional gusts of up to 20 mph will be possible overnight. Dry conditions are again expected for most if not all locations on Tuesday as shortwave ridging peaks over the area during the daytime hours. Mid-level moisture advection may lead to redeveloping stratus across portions of the area, particularly the eastern half of the CWA. This may help to limit daytime heating slightly, though temperatures are anticipated to be warmer than what was seen Monday. High temperatures will range from the mid 70s in the east to low 80s in the west. Breezy south winds will be prevalent for areas west of Highway 83, where gusts may be as high as 25 mph. With the continued push of better moisture into the Panhandle region, dew points look to climb into the mid to upper 50s. This combined with the warm temperatures should lead to some modest instability developing with MLCAPE values of 1500-2000 j/kg with 0-6km BWD values in the 25-35 knot range. Conditions will be supportive of strong to severe thunderstorms further west from the local area, the question is how far east does activity make it if at all. Shear vectors and corfidi vectors while initially look to steer any high plains activity into the local area during the afternoon, will make a sharp turn more south to north during the evening hours and so confidence in storm threat to the local area is low at this time. Though unlikely, should a storm form earlier in the afternoon the threat to the Deuel/Garden/Sheridan Counties line would increase. Since this outcome doesn`t appear likely, have decided to remove what little PoPs there were Tuesday evening. Another low-level jet is expected to develop Tuesday night and is anticipated to be stronger than the previous night`s. This in combination with better low-level moisture and increasing temperatures at h85, should see an even warmer morning on Wednesday with low temperatures in the 50s for all. Occasional wind gusts overnight could once again approach 20 mph. .LONG TERM...(Wednesday through Monday) Issued at 255 PM CDT Mon May 18 2020 Beginning 12z Wednesday. The long awaited trough from the west will begin its approach during the daytime Wednesday. Height falls will begin early and persist through the daytime hours. Temperatures will be warm again with highs generally in the upper 70s, or 5-8 degrees above normal. Moisture advection across the western tier of counties will reintroduce partly to mostly cloudy skies by the afternoon. A strong vort max will pivot across the eastern periphery of what will by then be a negative tilt trough centered over the northern Rockies. This, working in concert with a surface cool front expected to take shape during the day, will be the focus for scattered rain and thunderstorms during the late afternoon and evening. Have slowed down the arrival of precipitation slightly locally owing to a strong capping inversion and timing of the greatest forcing for ascent. As a result, only have Slight Chance PoPs along and west of a Lewellen to Gordon line prior to 00z Thursday. Temperatures at h7 will be in the low teens, which is leading to strong CIN. What storms that do form on the High Plains will likely be moving north to north- northeast due to the highly amplified flow with shear vectors and corfidi vectors all oriented south to north. Believe the strong to severe thunderstorm threat to be rather limited locally as instability drops off significantly the further east you get with nearly 2000 j/kg of MUCAPE along the western border or Garden County to less than 1000 j/kg east of Highway 61. Do believe some eastward progression of convection is expected late Wednesday into early Thursday, however, due to the surface boundary moving east with time but no strong to severe weather is expected overnight. The frontal boundary will likely stall across the area on Thursday and serve as the focus yet again for rain and thunderstorm development during the day. A second vort max rotating around the parent trough across the northern Rockies will be the source for forcing as divergence aloft increases during the day. How far east this frontal boundary makes it will play a large role in where the greatest PoPs will be and thus the greatest QPF falls. For now, have Likely PoPs along and east of a North Platte to Ainsworth line but adjustments in the coming days will be likely. High temperatures Thursday are medium confidence at best with general highs in the 70s expected. The extended forecast remains active as troughing continues in the west with additional disturbances moving through the area and an unimpeded flow from the Gulf of Mexico. Temperatures heading into the weekend look to be above normal with 70s and 80s expected Friday and Saturday but falling to the 60s and 70s for Sunday and Memorial Day. Right now, the holiday weekend appears to be fairly active across the region but long, appreciable breaks are likely locally with the best rain/thunderstorm chances on Saturday. High pressure works in the start the following week with an anomalous disturbance churning over Texas but cutting off local moisture sources and keeping forcing for ascent out of the area. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 634 PM CDT Mon May 18 2020 Main aviation concern will be the development of IFR ceilings late tonight. IFR ceilings are forecast to develop in central Nebraska including KBBW and expand westward to include a BKN004 ceiling at the KLBF terminal by 11Z and lasting until at least 13Z. Latest mesoscale models indicate stratus development, with the westward extend still in question. IFR ceilings may also include KVTN, and have included a SCT004 12Z-15Z. Further refinement is likely with the next scheduled TAF issuance at 06Z. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Roberg SHORT TERM...Jurgensen LONG TERM...Jurgensen AVIATION...Roberg
East Central Florida Forecast Discussion
National Weather Service Melbourne FL
924 PM EDT Mon May 18 2020 .DISCUSSION... Currently-Overnight...Showers and a few storms ascd with diurnal heating and large scale instability across the region will move offshore the Treasure Coast over the next couple of hours. The recently updated forecast keeps isold/sct chcs possible during the overnight, mainly due to shortwave axis which will move across the state overnight. stronger jet level winds combined with suitable moisture and UL temp profile may lead to onset of some additional convection overnight, esp across the south, where HRRR guid suggests some re-development overnight. Tuesday...As the UL wave shifts east of the area by Tuesday morning, models have drier air moving in, which will gradually end rain chances across north central Florida. However, sufficient moisture and instability to the south, ahead of a weak surface trough may lead to additional scattered showers and storms into the late morning and afternoon, especially across Okeechobee County and the Treasure Coast. A few stronger storms may still be possible with this activity, before it shifts offshore by the evening, with rain chances then ending across the area. && .AVIATION... Will keep a low shower chance overnight most of area, with mention of showers across southern sites primarily VRB-FPR-SUA. A dry slot in the mid levels will work in north of a KISM-KTIX line on Tuesday substantially lowering rain chances with mainly VFR conds. Expect SCT SHRA/TSRA in the KVRB-KSUA corridor Tue afternoon. && .MARINE... Tonight...Main boating concern will be with a few stronger storms that may still push offshore through midnight, south of Sebastian Inlet. Otherwise winds will be out of the S/SW around 10-15 knots with seas 2-4 feet. && .MLB WATCHES/WARNINGS/ADVISORIES... FL...None. AM...None. && $$ JP/JC