Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/10/21

Area Forecast Discussion
National Weather Service La Crosse WI
1030 PM CDT Fri Jul 9 2021 .SHORT TERM...(This evening through Saturday) Issued at 233 PM CDT Fri Jul 9 2021 Main focus is on rain/thunderstorm potential into Saturday. Scattered showers/storms have been developing across southern MN within an elevated frontal zone as a weak shortwave trough passes. Late this afternoon into tonight, expect the primary instability axis to remain south and west of the area with some modest MUCAPE encroaching on southwestern portions of the area. Confidence isn`t very high on how convection will evolve into tonight. In general, though, think additional convection will ramp up along the nose of low-level jet/moisture transport this evening. Although guidance varies on the strength of the moisture transport, generally the nose of the low-level jet is should focus across central IA with storms quickly progressing southward into the instability axis. With the surface-based instability and steeper mid-level lapse rates relegated to areas farther southwest, not expecting much for a severe weather threat, but could not rule out some hail/gusty winds with any storms, especially across northeast IA. Expect the greatest risk for heavy rainfall to be south of the area, but any storms could produce high rain rates and locally heavy rainfall if storms train over the same area. A surface low is expected to move towards the Mid-MS Valley on Saturday ahead of the deepening upper trough. Overall there appears to be a trend for at least some showers to spread across at least southern parts of the region on Saturday with shortwave energy lifting across the area downstream from the main trough and mid- level deformation. Instability looks quite limited north of the surface low so thunder chances should be low. If the cloudier/showery solution holds, some locations could remain in the 60s for highs. .LONG TERM...(Saturday night through Friday) Issued at 233 PM CDT Fri Jul 9 2021 The potential for additional rain across the southern part of the area through the weekend and into early next week still looks to be in flux with plenty of uncertainty involved. Water vapor satellite imagery shows a couple of short wave troughs topping the western Conus ridge today. The first wave will slide through tonight and is expected to be responsible for the severe weather outbreak to the south of the local area. The second wave will then slide into the region late tonight into Saturday and is expected to have an upper level low develop with it over the Missouri River Valley. This scenario is generally agreed upon by the models but with some subtle differences in the placement of where the upper level low will be. These differences in turn impact how far north any associated rainfall may be. Give the uncertainty of where the upper level low may actually be, the rain chances will have to cover the most pessimistic outcome, which comes from the 09.12Z GFS which shows the potential for rain over much of the area from Sunday into Monday. The rain chances could possibly even extend into Tuesday depending of how fast (or slowly) the systems lifts out of the region. If this does occur, it should primarily just be showers as there looks to be little potential for CAPE development thus keeping the thunder threat pretty low. There looks to be another good shot at some widespread rains by the middle of next week. An upper level low should be moving across southern Canada with the trough extending south over the Upper Midwest. An embedded short wave trough in the mean long wave trough should help to generate showers and storms Wednesday and Wednesday night. It`s too early to know what the severe threat might be with this activity. The 09.00Z ECMWF would suggest the best CAPE stays to the south of the area with the deep layer shear also staying primarily to the south. The models are again showing differences in the timing of when this system may clear out of the region which will means the rain chances will persist in the forecast through the end of the next week. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) Issued at 1030 PM CDT Fri Jul 9 2021 Cigs: challenging forecast with cutoff upper level low hanging around the region, likely just south of the TAF sites. The MVFR/VFR line of clouds will be close as a result, with latest RAP holding it just south of KLSE but touching KRST. HRRR suggestive of the same thing. Improvement trending then for the evening. Not a ton of confidence here, but will follow these trends for now. WX/vsby: bulk of associated shra/ts with this system looks to hold just to the south. Could run into isold/sct convection around I-90 sat afternoon, but not a lot of agreement in the short term will keep dry for now and add if probabilities increase. Winds: east mostly 10 kts or less through the day Sat, looking to become more northeast/north later Sat night. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ SHORT TERM...JM LONG TERM...04 AVIATION...Rieck
Area Forecast Discussion
National Weather Service Bismarck ND
959 PM CDT Fri Jul 9 2021 .UPDATE... Issued at 957 PM CDT Fri Jul 9 2021 Around 830 PM CDT this evening, an isolated shower produced a funnel cloud in north central Mountrail County. With the loss of diurnal heating contributing to weakening low level lapse rates, atmospheric conditions are no longer expected to support the development of funnel clouds. Forecast expectations on both the coverage and intensity of showers and storms through the night have greatly decreased since previous updates. Convection has been much more sparse so far this evening, and lightning has been nearly non-existent within the state. It appears that 00Z guidance is catching onto these trends. Notably, the local maxima of the 00Z HREF probability- matched mean QPF from 00-12Z are less than 50 percent of their values from the previous run. Furthermore, the 00Z Bismarck RAOB only sampled 1.15 inches precipitable water. While Bismarck is displaced to the west of the PWAT maximum, this value is still around one to two tenths of an inch lower than what is being simulated by the 00Z RAP and SPC Mesoanalysis. Taking all this evidence into consideration, we have removed the mention of heavy rain from the forecast. We will maintain the mentions of isolated to scattered showers along with isolated thunderstorms, but probabilities have been trended down. Lastly, the mention of patchy fog was expanded based on the latest RAP guidance. UPDATE Issued at 717 PM CDT Fri Jul 9 2021 Overall, only minor adjustments were made to the forecast with this update. Scattered showers have shown a slight increasing trend over the past few hours from north central North Dakota into the James River Valley. Despite the presence of 1000-1500 J/kg MLCAPE with little to no MLCIN, poor mid level lapse rates appear to be a detriment to the lightning potential. Therefore, we have limited the mention of thunderstorms to isolated this evening through tonight. The focus for scattered shower and isolated thunderstorm activity is still expected to pivot over south central North Dakota tonight, mainly along and east of the Missouri River. Precipitable water as high as 1.5 inches, warm cloud layer depth greater than 3000 m, and slow storm motions will promote a heavy rain potential with any shower or storm. However, due to the scattered nature of the convection, the risk of heavy rain will be highly localized, as can be inferred by 12Z HREF QPF output. Patchy fog was added to the forecast for parts of western and central North Dakota late tonight into Saturday morning. This potential is supported by a moisture-rich boundary layer with light winds. Recent runs of the RAP were utilized to depict the placement of the fog mention. && .SHORT TERM...(This evening through Saturday) Issued at 230 PM CDT Fri Jul 9 2021 Forecast highlights in the short term period will be chances for showers and thunderstorms through Sat morning. Currently, mid level circulation remains evident on satellite imagery over southwest/south central North Dakota. Area of associated showers persists over south central ND into portions of the James River Valley. Extensive area of clouds also persists across much of western and central ND, which has effectively cut daytime high temperature potential by several degrees. Another mid level trough will set up across the region later today into tonight, resulting in another round of scattered showers/storms from eastern Montana through central ND developing later this afternoon and evening. Elevated atmospheric moisture (PWATs 1.5 to 1.75") coupled with the mid level forcing and slow storm motion will keep a threat for locally heavy rain over portions of central North Dakota, so will maintain this wording in products. .LONG TERM...(Saturday night through Friday) Issued at 230 PM CDT Fri Jul 9 2021 Seasonal temperatures and periodic chances for showers/storms highlights the long term period. Surface high pressure builds across the Dakotas on Saturday, with lingering chances for showers across the southwest and south central areas of North Dakota. Highs will range in the 80s as we will see more sunshine compared to previous days. Upper level ridge builds across the Northern Plains for Sunday, resulting in warm and dry weather for the region. Thereafter, we will be under a quasi-zonal flow regime Monday through the end of the week, where we will see, on average, seasonal temperatures and periodic chances for showers and storms as several embedded waves move through aloft within the flow. Extended models then strongly suggest a ridge of high pressure building across the western CONUS and Rocky Mountains, which would support a trend towards hot and dry weather as we near the last week and a half of July. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 957 PM CDT Fri Jul 9 2021 Scattered showers are possible across much of western and central North Dakota this evening through tonight, ending from north to south by Saturday afternoon. The highest probability of showers is at KJMS this evening, shifting to KBIS overnight. Ceilings are likely to remain at VFR levels under showers, but visibility reductions to MVFR or IFR levels are possible. Lightning cannot be ruled out, but its probability is quite low. Additionally, patchy fog may develop later tonight, with the highest potential at KDIK. Outside of showers and fog, VFR conditions are expected with light and variable winds. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Hollan SHORT TERM...NH LONG TERM...NH AVIATION...Hollan
Area Forecast Discussion
National Weather Service Boise ID
831 PM MDT Fri Jul 9 2021 .DISCUSSION...Increasing heat and smoke through the weekend. The heat will be due to amplification of the upper ridge in the Great Basin. The smoke will come in from two main fires, one near Klamath Falls in south-central Oregon, and the other northwest of Reno (in northeast California). With southwesterly flow aloft the HRRR smoke model takes the Oregon smoke across Baker County, the central Idaho mountains, and the Camas Prairie, while the California smoke drifts over Idaho south of the Snake River. That leaves the least smoke in Malheur County/OR and the Treasure Valley through Saturday night. Skies will become smoky or at least hazy everywhere and should take a degree or two off high temps vs highs if the sky could stay clear. Even so, Saturday will become about 10 degrees hotter than today, and Sunday another couple degrees hotter than Saturday, and an Excessive Heat Warning will be in effect from Saturday afternoon until Monday evening in all zones except the Owyhee Mountains, west- central Idaho Mountains, and Camas Prairie. No updates for now. && .AVIATION...VFR. Smoke layers from wildfires will reduce visibilities at times. Surface winds: generally southeast 5-15 kts. Winds aloft at 10k feet MSL: west 10-20 kts. Density altitudes will remain high due to hot temperatures. Sunday Outlook...VFR. Smoke layers from wildfires will reduce visibilities at times. Breezy northwest winds in the afternoon. Density altitudes will remain high due to hot temperatures. && .PREV DISCUSSION... SHORT TERM...Tonight through Sunday night...Upper level ridging will expand over the region on Saturday, bringing warmer temperatures. We are surrounded by wildfire smoke at this time, so do not expect conditions to improve over the short term as winds aloft begin to weaken and shift to the southwest. Temperatures are expected to warm around 10 degrees on Saturday and a few more degrees on Sunday with record highs possible. Smoke will make the temperature forecast tricky, which may lead to slightly cooler temperatures. Temperatures should still reach 100 in the lower valleys and the Excessive Heat Warning will remain from Saturday afternoon through Monday afternoon. No precipitation expected in the short term. LONG TERM...Monday through Friday...Abnormally warm and dry conditions are expected throughout the week as high pressure remains locked in over the southwestern US. The ridge will flatten somewhat, allowing for westerly flow to move over the Pacific Northwest, but dry conditions are expected to persist. Wildfire smoke could become an increasing threat during the period. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...Excessive Heat Warning from noon Saturday to 9 PM MDT Monday IDZ012>016-030-033. OR...Excessive Heat Warning from noon MDT /11 AM PDT/ Saturday to 9 PM MDT /8 PM PDT/ Monday ORZ061>064. && $$ DISCUSSION...LC AVIATION.....ST PREV SHORT TERM...KA PREV LONG TERM....MC
Area Forecast Discussion
National Weather Service Caribou ME
1135 PM EDT Fri Jul 9 2021 .SYNOPSIS... Post Tropical Storm Elsa will track along the Downeast coast this evening and move into the Maritimes early Saturday. High pressure will cross the region Sunday through Monday. A warm front will approach Tuesday then cross the region Wednesday. && .NEAR TERM /THROUGH SATURDAY/... 942 PM Update: Took down Flash Flood Watch and the last Flood Advisory. Rain will be ending in eastern Aroostook County in the next two hours and the heaviest rain has moved out of the area. Prev Disc: Post Tropical Elsa will track near the Gulf of Maine/ Downeast coast this evening and overnight. Main hazards remain heavy rainfall along the coast, Downeast, and Southern Aroostook tonight. Additionally, there is a threat for a few higher wind gusts this evening, particularly along the saturated ground along the coast and central Washington County. High surf continues along the coast through Sat morning. For rain, much of the guidance continues to show the risk for flash flooding as Elsa pivots along the coast. This is based on WPC/RFC flash flood guidance as well as QPF. MRMS based CREST has been increasing across southern Maine as the main pivot point wraps around a large swath of synoptic rainfall currently falling up to 1" an hour. While Downeast is certainly a focus for this evening into tonight, the area with the most persistent rainfall through the afternoon has been from Southern Aroostook to just south of Greenville. As this band pivots through, also may see flash flood risk increase in this already moist surface soil. New wind headlines were issued to account for Elsa`s transition into a post tropical cyclone. The main concern was a band of stronger northerly winds wrapping around the center as it departs to NB. NAMnest and HRRR have shown this fairly consistently for runs today, bringing up to 40mph gusts from the NNW into central Washington County and coastal Hancock. Given the large amount of moisture wrapping around and into drier air on the back side, some of these gusts may show momentum transfer during transition. The Advisory was issued primarily for impacts due to recent saturated soil, seasonal dry conditions, and a quick wind shift from east to north this evening. Fog continues this evening as Elsa pulls away, becoming less dense towards Sat morning. Precip will cut off after midnight as well, with only a few remaining showers across far eastern Maine. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... High pressure will cross the region Saturday night through early Sunday with mostly clear skies. A cold front will then begin to approach northern Maine later Sunday afternoon with a chance of afternoon showers/thunderstorms across northern areas, with partly sunny skies Downeast. The cold front begins to cross the region Sunday night, reaching Downeast areas late. Could still have a chance of showers/thunderstorms across northern areas Sunday evening. Otherwise, expect decreasing shower chances with the loss of diurnal heating while the front moves south overnight. The front will cross the Gulf of Maine Monday then stall. High pressure will build across the region in the wake of the front Monday with mostly/partly sunny skies. Temperatures will be at near normal levels Sunday/Monday. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... High pressure will cross the region Monday night then begin to exit across the Maritimes Tuesday. Expect mostly clear skies Monday night. The stalled frontal boundary will start to move back north in the form of a warm front with the return flow around high pressure Tuesday. Expect increasing clouds Tuesday. Could also have the chance of an afternoon shower/thunderstorm. The warm front crosses the region Wednesday with a chance of showers/thunderstorms. Warm, humid conditions are expected Thursday and Friday along with a chance of mostly afternoon and evening showers/thunderstorms with diurnal heating. An approaching cold front could also help support thunderstorm chances Friday. Near normal level temperatures are expected Tuesday/Wednesday. Slightly above normal level temperatures are expected Thursday/Friday. && .AVIATION /04Z SATURDAY THROUGH WEDNESDAY/... NEAR TERM: VFR/MVFR from PQI to FVE will fall to MVFR with a brief period of IFR cigs due to steady rain. MVFR at HUL will fall to IFR this evening. All northern sites improve to MVFR by 06z with VFR by 09z. Winds light and variable becoming N 5-15kts after 03z. Southern sites IFR/LIFR with rain and fog will improve to MVFR cigs after 03z with improvement to VFR by 06z. BCFG will be possible through daybreak which may cause brief IFR conditions. E-NE winds 10-20kts early will shift N-NW 10-20kts with some gusts to 35kts at BHB possible this evening. LLWS is possible at BHB this evening. VFR expected all sites Saturday with N-NW winds 5-10kts. SHORT TERM: Saturday night...VFR. Light winds. Sunday... Generally VFR. However, variable conditions possible across northern areas late with any showers/thunderstorms. Southwest winds around 10 knots. Sunday night...Variable conditions with any showers/thunderstorms. Otherwise, VFR. Light winds. Monday/Monday night...VFR. Northwest/north winds around 10 knots Monday. Variable winds 5 to 10 knots Monday night. Tuesday...Variable conditions with any showers/thunderstorms. Otherwise, VFR. South/southeast winds 10 to 15 knots. Tuesday night/Wednesday..Variable conditions with any showers/thunderstorms, also with any fog Downeast. Otherwise, VFR. South/southeast winds 10 to 15 knots. && .MARINE... NEAR TERM: Wind gusts increase to Gale across the eastern waters this evening and overnight. Overall, easterly winds will be strong ahead of Elsa`s approach, lighter as circulation passes through the waters, then increasing once again from the WNW. Expect a few gusts up to 35 kt in the Small Craft Adv area, with these WNW winds, but more brief than the eastern Gale. Wave heights build this evening 7 to 10 ft with high surf along the coast. SCA level wave heights continue through Saturday decreasing to 3 to 4 ft. SHORT TERM: Winds/seas below small craft advisory levels Saturday night through Monday. Patchy fog Saturday night. Could have a slight chance of showers later Sunday night. && .HYDROLOGY... Current forecasts still bring storm totals of 2.5 - 4.0 inches, with locally higher expected. These totals combined with the intense rates will cause the threat for flash flooding in the Watch area. Upstream observations indicate conditions favorable for flash flooding that is expected to move into the region late this afternoon and evening. Rivers, especially small streams, are expected to rapidly rise, with major rvrs little flood risk due to prior low flow levels. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...High Surf Advisory until 2 PM EDT Saturday for MEZ029-030. Wind Advisory until 3 AM EDT Saturday for MEZ017-029-030. MARINE...Small Craft Advisory until 2 AM EDT Saturday for ANZ051-052. Gale Warning until 2 AM EDT Saturday for ANZ050. && $$ Near Term...VJN Short Term...Norcross Long Term...Norcross Aviation...VJN/Norcross Marine...VJN/Norcross Hydrology...
Area Forecast Discussion
National Weather Service Cheyenne WY
832 PM MDT Fri Jul 9 2021 .UPDATE... Issued at 831 PM MDT Fri Jul 9 2021 Upon coordination with the Storm Prediction Center, we have extended the Severe Thunderstorm Watch until 11 PM. UPDATE Issued at 738 PM MDT Fri Jul 9 2021 Grids have been updated as the Red Flag Warning will expire at 8 PM. Also adjusted the thunderstorm chances for the rest of the evening. && .SHORT TERM...(This evening through Saturday) Issued at 148 PM MDT Fri Jul 9 2021 Current radar imagery indicates storms developing east of the Laramie Range, with pea size hail reported and heavy rain. Both HiRes models have been fairly consistent with the overall convection development and storm motion, with the HRRR being highly favored in the forecast update. Will likely see a severe weather watch put in place over the next hour. Strong to severe storms are possible through midnight tonight, with the 1833z Ft Collins sounding indicating good directional shear, 2700 J/kg of CAPE, and 49kt of 0-6 shear. Main threats today include strong supercell storms producing large hail, flash flooding, and strong winds. However, cannot rule out a tornado or two with a favorable environments. Main changes from the early morning forecast has the second wave of convection looking much less impressive. Will need to monitor through the night to determine any additional watches needed after 9pm MDT. As we move into the early morning hours tomorrow, a cold frontal boundary is expected to continue digging towards the south. Showers and Thunderstorms are possible to continue through the early morning hours, primarily east of I-25. Otherwise, Saturday will cool down to the high 70s to low 80s behind the cold front, with some gusty winds around 20 to 25 knots, and precipitation chances significantly dwindling. .LONG TERM...(Sunday through Thursday) Issued at 411 AM MDT Fri Jul 9 2021 Key Messages: 1) Sunday will be the start of a brief warming trend into Monday with above normal temperatures and elevated fire weather conditions these two days. 2) Temperatures will drop back a few degrees Tuesday thru Friday with increased afternoon shower/storm chances. Pattern favors chances of at least isolated strong to severe storms during this period so stay tuned next week. Weather Discussion: Following the brief cool down Saturday as the closed H5 low departs east, shortwave ridging will shift east across WY in its wake Sunday and Monday. Sunday will likely be the driest of the week as 0.3" to 0.6" PWATs range west to east under subsident dynamics. Monday will be the warmest of the period as H7 temperatures range from +14C east to +20C west. Mid to upper 90s are likely in the lower elevations of the High Plains and NE Panhandle, with low 90s elsewhere. Winds will be light through the atmospheric column overall and should preclude the need for fire headlines. However, minimum relative humidity vales will fall into the teens Sunday and moreso Monday for elevated to near-critical fire weather. By Tuesday, a shortwave trough is advertised to come ashore and swing across the Pacific NW to Montana mid-week. H5 pattern will flatten in-between the trough north to the lower amplitude ridge south - allowing embedded impulses to traverse the region for local lift enhancement. Tuesday - Friday looks to be an active period of diurnal showers/storms. Nuances of timing and available moisture plus resultant instability will need to be monitored for strong to severe storm potential. Likely Marginal severe risk categories through much of next week with possibly of a few Slight Risk days. Stay tuned through next week on day to day hazards and timing. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 521 PM MDT Fri Jul 9 2021 Wyoming TAFS...VFR at Rawlins and Laramie. Wind gusts to 48 knots at Rawlins, and 33 knots at Laramie, until 02Z. VFR at Cheyenne until 06Z, then MVFR until 13Z, then VFR. Thunderstorms in the vicinity until 02Z. Wind gusts to 25 knots from 02Z to 06Z, and to 22 knots after 13Z Saturday. Nebraska TAFS...VFR, with occasional MVFR in thunderstorms producing wind gusts to 45 knots until 06Z. Thunderstorms in the vicinity from 06Z to 14Z. Wind gusts to 26 knots until 06Z, then to 25 knots after 15Z Saturday. && .FIRE WEATHER... Issued at 148 PM MDT Fri Jul 9 2021 Above normal temperatures recorded today with humidities in the low teens across Carbon and Albany counties and westerly winds gusting to 35 MPH ahead of a frontal passage. Some shower and thunderstorm activity possible with the frontal passage, which will ease fire weather concerns as we go into the evening. Saturday will be the coolest day with higher humidity and weaker winds, but that relief is short-lived as temperatures warm back up to well above normal with humidity dropping to 12 to 20% Sunday into early next week. Looking at next week, Monday, Thursday, and Friday appear to be the days wit elevated to near- critical fire weather conditions with humidity below 15% and winds gusting near 25 MPH for Carbon and Albany counties. As a few shortwaves pass through the region, afternoon thunderstorms are possible Tuesday through Thursday, especially for far eastern Wyoming and the Nebraska panhandle. Any fire weather headlines will be evaluated closer to the dates. && .HYDROLOGY... Issued at 148 PM MDT Fri Jul 9 2021 Flash Flood potential on the Mullen burn scar through next Monday will be be none to limited. Risks will increase next Tuesday through Friday as more showers and storms become possible across the mountains. Storms today will be too far east and then after a cooler drier day Saturday, warm and dry conditions occur Sunday and Monday. Additional disturbances will occur Tuesday and beyond to support more activity and higher moisture content. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ UPDATE...RUBIN SHORT TERM...MD LONG TERM...JSA AVIATION...RUBIN FIRE WEATHER...JSA/MD HYDROLOGY...JSA
Area Forecast Discussion
National Weather Service Des Moines IA
721 PM CDT Fri Jul 9 2021 .DISCUSSION.../Tonight through Friday/ Issued at 353 PM CDT Fri Jul 9 2021 Forecast Highlights -Severe storms and heavy rain possible tonight -Cool and rainy weather over the weekend into Monday Tonight into Saturday morning...Outflow boundary from large supercell earlier today has drifted into western and southwest parts of the forecast area and remains clearly evident via visible satellite and base reflectivity. This could become a trigger mechanism for additional convection later this afternoon and evening. The atmosphere is certainly primed for additional severe weather across the western and southern portions of the forecast area. Surface based CAPE has increased to around 5000 J/kg in southwest Iowa with the gradient setting up from around Denison southeast to Lamoni. Cap has eroded with 700mb temp around 10C and fairly steep lapse rates have developed over the west. Shear is strong, 0-6km shear around 50 knots and effective shear even higher. Low level shear, at least the 0-1km shear, is only around 10 knots but latest HRRR and RAP soundings suggest a bit higher later this afternoon and evening. The Bunkers right-moving supercell motion is southeast and if any storms initiate along the aforementioned outflow boundary, they should follow this motion which lines up well with the instability gradient. Challenging to believe any of the hires models as they did not perform well with the large hail producer today. Nonetheless, the latest NAMNest does suggest development along the outflow boundary by around 00z and confidence is increasing this scenario will pan out. Timing might be a bit later for redevelopment, but agree with the location in the vicinity of the outflow. Storm mode is likely supercell with initiation with hail and damaging wind and possibly tornado or two with the amount of low level helicity and effective helicity. Expect storms to quickly combine and develop into a more of a bowing segment as it moves southeast into Missouri. Another round of storms is possible with a strong shortwave causing convection over the high plains of Nebraska and this convection looks to reach the CWA by the overnight hours towards Saturday morning. Low confidence this MCS holds together and/or remains severe as it depends how favorable the atmosphere in southwest Iowa is going be after the potential convection in the same location this evening. Certainly heavy rain is a threat with PW as high as 2.00 to 2.25 inches across the south and decent moisture transport into the state. Given the uncertainty if the MCS will roll into southern Iowa or northern Missouri, kept the Flash Flood Watch confined to the southeast for now. Saturday into Monday...the surface and upper level low pressure stalls over the region into Monday providing additional rain chances and cooler weather through the weekend. Severe weather potential remains low with the lack of significant instability over the weekend. Tuesday through Friday...the upper low finally gets kicked eastward with the upper level ridge over the southwest expanding east. A cold front and strong upper level low looks to push thorugh the region Wednesday night into Thursday. && .AVIATION.../For the 00Z TAFS through 00Z Saturday evening/ Issued at 720 PM CDT Fri Jul 9 2021 Primary concern for TAFs this cycle was trying to time overnight convection. While severe thunderstorm potential continues for the next few hours, confidence is highest in greatest thunderstorm coverage occurring in the 03-12z timeframe across central and southern Iowa. Any severe weather threat this evening will transition to flooding concerns overnight. Coverage will be less at KFOD, KMCW, KALO, and better at KDSM and KALO. Convection lingers but gradually decreases in coverage during the day on Saturday. && .DMX WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch through Saturday morning for IAZ085-086- 095>097. && $$ DISCUSSION...Podrazik AVIATION...Hahn
Area Forecast Discussion
National Weather Service Grand Forks ND
649 PM CDT Fri Jul 9 2021 .UPDATE... Issued at 649 PM CDT Fri Jul 9 2021 Surface high pressure is holding over the western Great Lakes while a low pressure system is expected to scoop just south of the tri-state area... through eastern NE, through the overnight period into Saturday morning. Deep convection which earlier tracked through western and central ND, should dissipate in northeast SD according to recent HRRR guidance, though various CAMS keep some convection into the far southern RRV and adjacent portions of westcentral MN into early evening. An updated Aviation Discussion is attached below. && .SHORT TERM...(This evening through Saturday night) Issued at 259 PM CDT Fri Jul 9 2021 Any rain chances in our western counties tonight then temperatures will be the main issues for the period. Several weak shortwave troughs continue to dig through the region, mostly following a central ND to SD/MN track. There continues to be some shower activity in south central ND thanks to one of the weak shortwaves, although with MU CAPE values of 500 J/kg at best the strength of the convection has remained fairly weak. CAMs have the showers and thunderstorms over central ND slowly moving southeastward this evening, clipping some of our western counties. Most recent radar loop seems to be trending more towards the drier HRRR rather than some of the wetter CAMs. However, can`t completely rule out a bit of rain moving into our west, so kept some 20-50 POPs going. The main shortwave digging down through SD tonight will strengthen and cut off to our southeast Saturday into Saturday night. Weak surface high pressure and dry conditions will set in by afternoon as the system pulls further away from our CWA. Temps will be a bit warmer and more firmly in the 80s with more sunshine on Saturday. .LONG TERM...(Sunday through Friday) Issued at 259 PM CDT Fri Jul 9 2021 Widespread hazardous weather in the long term period is currently not expected. That being said, there is a chance for perhaps some thunderstorms around the Monday-Tuesday timeframe with an assoc cold fropa, as well as a greater than 30 percent chance for temperatures above 90 degrees. Upper ridging will build into the region from the west Sunday allowing temperatures to near and break 90 for most. After Sunday, heights decrease as a trough moves through Canada with perhaps a smaller system moving through the Central Plains into the Upper Midwest. This trough pushes a cold front or inverted surface trough through the Dakotas into the Upper Midwest around Monday and Tuesday. This forcing mechanism should allow for some convection. There isn`t a great signal for very robust convection at this time due to an expected lack of appreciable instability and generally weak forcing/kinematic regime aloft. This may change some as time nears, but current guidance suggests convection to remain on the weaker side. Getting into mid to late next week, heights will be back on the rise as a ridge is anticipated to again build over the intermountain West. This increases chances for near or above 90 degree temps late in the week. This is depicted nicely in ensemble means and NBM probabilities. This increase in heat content and chance to be on the periphery of the upper ridge may bring chances for storms back into the forecast late next week, although details remain far from clear at this time. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 649 PM CDT Fri Jul 9 2021 Expect VFR and light winds across the FA, throughout the forecast period. Generally fair skies with light and variable winds will extend from northeast ND, across the Red River corridor, and across all of northwest MN. Areas of mid level cigs and southeast winds to 10kts are mainly along and west of a RUG-BAC-BWP line, and will steadily shift southward and eventually out of southeast ND through 10z. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. $$ UPDATE...Gust SHORT TERM...JR LONG TERM...CJ AVIATION...Gust
Area Forecast Discussion
National Weather Service Flagstaff AZ
146 PM MST Fri Jul 9 2021 .SYNOPSIS...High pressure remains in control through the weekend, delivering hot daytime temperatures through Sunday. A slight increase in monsoonal moisture will take place over the weekend, however showers and storms are expected to remain isolated to the Mogollon Rim. More significant moisture looks to return next week, with greater chances for showers and thunderstorms. && .DISCUSSION...Scattered showers and thunderstorms have develop across the the Mogollon Rim, Chuska Mountains and Black Mesa this afternoon. Activity over the far northeast is expected to diminish within the next few hours. Latest HRRR guidance has activity over the Mogollon Rim increasing over the next couple of hours, with a line of thunderstorms moving off the Rim into this evening. Much of the activity should diminish around 8pm, with only a few light showers and storms remaining through 10pm over southern Yavapai and Gila counties. Primary threats will be strong gusty outflow winds and brief heavy rainfall, a few of the stronger storms also have the potential to produce some small hail. The strong ridge over the southwest will remain in place through the weekend, with heights maximize over northern Arizona on Saturday. As a result, hot temperatures are expected to continue over the area, with Saturday being the warmest day. Excessive Heat Warnings remain in effect for the lower elevations of Yavapai County as well as the Grand Canyon. Much of the showers and thunderstorm activity this weekend will be suppressed with the stable air mass in place, however slight chance for showers and storms will exist along the Mogollon Rim and higher terrain during the afternoon hours. For the start of next week, the ridge begins to degrade and wobble around the southwestern United States. Monsoonal moisture beings to surge northward into Arizona, bringing the chance for more widespread showers and thunderstorms for much of the upcoming week. Much of the EPS members, and to a lesser extent the GEFS members, are in agreement with an increase in moisture into northern Arizona. Cooler, more seasonable temperatures and light winds are also expected for next week. && .AVIATION...For the 00Z package...VFR conditions are expected to prevail for much of the period. Local MVFR conditions will be possible in showers and thunderstorms mainly along and south of a KGCN-KFLG-KSOW line. More isolated showers and storms will be possible after 20Z Saturday. Gusty and erratic winds will be possible in and around thunderstorms. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Isolated showers and thunderstorms are expected Saturday and Sunday, mainly along the Mogollon Rim and south. Primary hazards will be strong gusty outflow winds, brief heavy rainfall, and lightning. Temperatures are expected to remain hot along with light northwest/north winds. Monday through Wednesday...Shower and thunderstorms chances increase each afternoon areawide for the start of next week. Cooler more seasonable temperatures and light winds are also expected. && .FGZ WATCHES/WARNINGS/ADVISORIES... Excessive Heat Warning until 8 PM MST Saturday FOR AZZ037. Excessive Heat Warning until 8 PM MST Sunday FOR AZZ005-006. && $$ PUBLIC...Humphreys AVIATION...Humphreys FIRE WEATHER...Humphreys For Northern Arizona weather information visit
National Weather Service Hastings NE
625 PM CDT Fri Jul 9 2021 .DISCUSSION...(This evening through Friday) Issued at 500 PM CDT Fri Jul 9 2021 Main forecast concern is the potential for severe thunderstorms tonight and Saturday and ongoing hot/humid conditions. Uncomfortably hot and humid conditions have come to fruition this afternoon across the entire area, with some areas even climbing into the dangerously hot and humid range with heat indices near 105F. The highest HI`s are across north central KS, but even some areas further N from GRI to JYR are near 105F, owing to weaker mixing and strong evapotranspiration. One could argue conditions are actually worse along I-80 than north central KS due to much lighter wind speeds. Luckily, though, this is a one day ordeal, as much cooler conditions arrive behind a cold front tonight. The ongoing Heat Advisory is on track to expire at 01Z this eve. Severe thunderstorms are forecast to become an increasingly greater concern by mid to late evening and continue into the overnight. Will start by saying the overall severe threat has seemingly increased compared to 24 hrs ago, and there is some concern that at least portions of the CWA could see significantly high wind gusts of 70+ MPH. The main change from last couple of forecasts is that instability has trended higher, and further W. For example, HRRR MLCAPE for the LXN area at 00Z this eve has trended from 2000-2500 J/kg on yesterday`s 12Z and 18Z HRRR, to over 3500 J/kg on latest HRRR runs. This seems reasonable given Tds that have held firm in the low 70s, even around LXN where models progged Tds to fall into the low 60s by aftn. The higher instability values also extend further W into central and western Neb. This should make it easier for activity in the W Panhandle now to organize into a forward propagating MCS and maintain it`s intensity as it moves E thru the late eve and overnight. Shear is not lacking, and is actually quite impressive for July as a 50-60kt H5 speed max overspreads the instability axis. Magnitude of instability and shear now argue for a decent potential of sig severe, but this will also depend on how convective activity evolves W of here this eve. HRRR and NAMNest simulated reflectivity and sfc wind gust output have suggested a trend towards a more organized event, and more linear, which are usually good signals for at least localized significant wind gusts. Don`t want to discount the hail potential, either, but this will largely depend on storm mode. Some embedded supercells within a broader line are certainly possible. Also, forecast 0-3km shear vector magnitude and orientation, along with rich low level moisture, suggest some brief QLCS spin-ups can`t be ruled out either. Quick storm motions are expected, which should keep the heavy rain potential fairly low. One area to watch would be from Ord to Geneva as these areas received rainfall last night, but overall, most of the area has been dry of late. A more likely hydro scenario would be short- lived urban issues due to brief but torrential downpours. Model MUCAPE progs suggest the first round will scour much of the area of its instability prior to 06Z, but just enough CAPE may linger to combine with additional vort lobes, continued strong effective deep layer shear, and lowering freezing levels to keep a hail threat going a few hrs longer. Saturday continues to look like a messy day with off and on scattered tstms possible pretty much everywhere and at any time as several vort lobes rotate into the deepening trough over IA/MO. Much cooler mid level temps will essentially leave the entire area uncapped to any sort of sfc heating, so may see an uptick on convective coverage/intensity as early as 16Z to 18Z. 1-2K J/kg of CAPE and 25-30kt of deep layer shear may be enough to support some iso pulse-type marginally severe tstms (nickel-quarter size hail) given seasonably low WBZ levels, esp across roughly S half of CWA. Lgtn and hvy downpours (PWATs linger near 1.5" and tall, skinny CAPE) will likely be greatest concern for those with outdoor plans. Expect decr coverage/intensity thru the eve as daytime heating fades. Highs will be much cooler and range from mid 70s N, to mid 80s S. Sunday continues to look like the best day of the weekend. Models are still a bit mixed with regards to position of upper low and thus how far W moisture will wrap around. Have some slgt chc PoPs lingering over E third of CWA thru the AM, and may need to extend into PM hrs if trends from 15Z RAP and 18Z GFS continue, but NAM and EC are drier. Regardless, overall pcpn chcs are much lower Sun compared to Sat and Sun will still be pleasant with highs in the 70s/80s and low humidity. Wind will start off the day on the breezy side (so may even be a bit chilly in the AM), then gradually decline thru the aftn and esp eve. Little time spend on the extended periods. Mon and Tue are still mainly dry with highs climbing from the 80s into the 90s. Pattern may turn unsettled for middle to later portions of next week, but confidence on details are low attm. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Sunday) Issued at 619 PM CDT Fri Jul 9 2021 Main forecast concern for this period will come mid-late evening, as thunderstorm activity is expected to be pushing in from the WNW. Still some uncertainties with the exact timing, have the strongest winds coming through between 04-06Z. Currently have a tempo group with 45KT gusts at both places, but higher gusts certainly not out of the question. Through the rest of the overnight hours and into Saturday, plenty of uncertainties remain, as the potential for at least scattered showers and thunderstorms continues. Felt that the early-mid morning and mid-late afternoon hours had the better chances for precip, so kept a VCTS mention going during those times. Otherwise, once the main push of storms comes through later this evening, have winds NWrly in nature, but confidence in just how winds evolve is not high. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...Heat Advisory until 8 PM CDT this evening for KSZ005>007-017>019. && $$ DISCUSSION...Thies AVIATION...ADP
Area Forecast Discussion
National Weather Service Gray ME
1048 PM EDT Fri Jul 9 2021 .SYNOPSIS... Tropical Storm Elsa will cross the Gulf of ME today. Very heavy rain is still possible across the region with potential for flash flooding, especially in areas along and just inland of the coast. Some gusty winds are possible along the coast along with large breaking waves. The remnants of the tropical storm will depart the region tonight with seasonable temperatures and dry weather expected this weekend. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... 1030 PM Update... Significant updates to the forecast were made earlier this evening with package update. The steady, heavy rain associated with Post Tropical Cyclone Elsa has shifted out of the region per latest radar imagery. In its wake, scattered showers will continue to develop. The precipitation over northern areas has diminished, while showers continue near the Massachusetts state line, similar to the latest HRRR. Over 4 inches of rain fell in a few spots today, mainly along and near the coastline. The significant rainfall totals will allow local tributaries to remain high throughout the night despite the dry antecedent conditions. Made minor tweaks to temperature, dew point and wind forecasts in the near term portion of the forecast. Patchy to areas of fog may develop during the night per the latest HREF ensemble mean with plenty of low level moisture remaining in place. Update... Have updated the forecast to remove the flood watches from western portions of the forecast area. Prev Disc... Elsa will accelerate northeastward through the Gulf of Maine this evening with the back edge of the rain soon to clear east of New Hampshire. Moderate to heavy rain will continue south of the mountains in Maine with a focus along the Mid- Coast. Here expect rainfall rates around 1 inch per hour through about 7 PM. The back edge of the rain will clear Maine zones from west to east and should be east of the area before sunset. Latest satellite imagery shows some clearing skies over upstate New York with partial clearing expected across southern New Hampshire early this evening with some clearing over southern Maine late this evening. Mesoscale guidance suggest there will be burst of north to northwest winds behind Elsa`s remnants with gusts to 20 mph this evening. Mid level trough axis will still be to our west through the first part of tonight. Partial clearing over upstate New York has allowed the atmosphere to destabilize leading to scattered convection. Latest RAP analysis suggests that partial clearing into New Hampshire this evening with lead to about 500 J/kg of SBCAPE to develop before sunset. This will bring slight chances for scattered convective showers to develop in the wake of Elsa. Latest mesoscale guidance suggests that these showers or thundershowers will be weak and short lived, but cannot rule out additional precipitation chances across the area through late this evening after Elsa has cleared the area. Later tonight some decaying convection is expected to track across southern New England possibly scraping along southern areas. Have kept slight chances for showers here overnight and early Saturday morning along with areas of patchy fog across much of the area tonight. Lows tonight will range from the mid 50s north to mid 60s south. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/... High pressure builds into the area Saturday while cyclonic flow remains aloft. A mostly dry day is expected, although cyclonic flow aloft may lead to a stray afternoon shower. Skies will be partly to mostly sunny with highs in the 70s. High pressure continues to build over the area Saturday night for mostly clear skies and lows into the 50s to near 60F across southern New Hampshire. && .LONG TERM /SUNDAY THROUGH FRIDAY/... The East Coast upper level ridge begins to reestablish itself rather quickly to start out the extended forecast. The Euro ensemble mean continues to show rapid height rises at H5 on Sunday along and off the Eastern Seaboard. Meanwhile, a long wave trough will approach from the Plain States which will be blocked and cutoff by early next week. Some moisture will attempt to rotate around the periphery of the upper level ridge, allowing for a chance for showers in our region. This will mainly be over southern section of the forecast area. By Tuesday, 12Z guidance suggests the closed low will begin to open up and move east. This will allow for scattered showers across New Hampshire and western Maine. Sufficient instability may allow for a few thunderstorms as well. This wet pattern will continue late in the work week as another trough crosses the forecast area. && .AVIATION /02Z SATURDAY THROUGH WEDNESDAY/... Short Term...VFR conditions at KHIE and KLEB are expected to drop to IFR tonight in lowering cigs and reduced vsby in BR or fog. IFR conditions at KCON and KMHT may briefly improve to VFR this evening before dropping to IFR overnight in lower cigs and reduced vsby in BR or fog. IFR/LIFR conditions are expected to continue overnight at remaining terminals. Conditions improve to VFR at all terminals Saturday morning and lasts through Saturday night. Long Term...Ceilings begin to lower Sunday into Monday over southern sections, namely southernmost New Hampshire in close proximity to a warm front. Some IFR conditions will develop in showers and any scattered thunderstorms mainly during the afternoon and evening hours Tuesday and Wednesday. Patchy fog will locally lower visibilities during the night as moisture levels will remain high. Mostly VFR conditions on Thursday or Friday. However, there may be an afternoon thunderstorm as well during this period. && .MARINE... Short Term...SCAs have been extended for the outer waters for most of the day on Saturday mainly due to high seas. Long Term...Both winds and seas will remain below SCA thresholds through the period. && .HYDROLOGY... The steady, heavy precipitation has shifted east of our region. Will continue to monitor some of the smaller tributaries across the region as water levels will remain high. Drier air enters the region overnight and on Saturday. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...High Surf Advisory until 11 AM EDT Saturday for MEZ023>028. NH...High Surf Advisory until 11 AM EDT Saturday for NHZ014. MARINE...Small Craft Advisory until 5 PM EDT Saturday for ANZ150-152- 154. && $$ NEAR/SHORT AND LONG TERM...Cannon
Area Forecast Discussion
National Weather Service North Platte NE
629 PM CDT Fri Jul 9 2021 .SHORT TERM...(This evening through Saturday night) Issued at 321 PM CDT Fri Jul 9 2021 Obvious trigger for severe storm development is moving through WY this afternoon. Storm activity is firing on the Laramie Range and moving east and southeast. The Bunkers storm motion in the NAM and RAP models backed by the HRRR and NAMdng models suggests a southeast storm motion toward Interstate 80. Meanwhile, the model consensus however suggested activity would develop on the Pine Ridge and move through the Sandhills. This could still happen given the developing cumulus field in that area. Given the very strong shear, 0-6km and 0-8km of 50 kts to 75 kts, very large hail is the concern where ever storms develop. The NAM soundings also show a pocket of dry air forming in the low to midlevels of the atmosphere which would support strong winds, perhaps coincident with the hail. Such was the case across wrn SD Thursday evening with an isolated storm which produced 2"+ hail and 60 to 70 mph winds. The very strong shear which results in Bulk Richardson number of 50 or less across wrn Nebraska could limit the severe storm coverage to isolated coverage with one or two discrete storms, but this is difficult to predict. The severe weather parameters, including an increase in CAPE, suggest upscale growth near and east of highway 83 this evening. SPC suggested a 2 percent tornado risk across wrn Nebraska and this is based on a very modest warm sector opening up across the Cheyenne divide and perhaps parts of the Pine Ridge as suggested the RAP model. The low level vorticity along the warm front combined with stretching caused by daytime heating could potentially support tornado development. There is also the prospect of a second or third round of thunderstorms developing late this evening and overnight before all of the storms exit east by 12z Saturday. A check on the elevated instability in the NAM and RAP soundings, suggests the potential for a few additional severe storms capable of large hail. The elevated CAPE in these models varies from over 3000 J/KG in the RAP to less than 2000 J/KG in the NAM. This instability and the very strong shear is concerning. Thus, the potential for early evening severe weather is obvious but the prospect of overnight severe weather is uncertain. The models are in very good agreement forming a cut-off low across Iowa Saturday. The NAM shows elevated instability along and east of highway 83; around 1000 J/KG of CAPE which should support thunderstorms with the potential for small-subsevere hail. The loss of daytime heating Saturday evening should cause most of the this rain activity to dissipate. The thunderstorm forecast tonight uses the short term model blend plus the HRRR and NAMdng. This forecast attempts to drive the thunderstorm chances south toward and south of Interstate 80 as suggested by the HRRR and NAMdng. The short term model blend is farther north across the Sandhills. The short term model blend was the basis for the shower and thunderstorm chances across ncntl Nebraska Saturday. This rain is associated with cold air aloft from the developing upper level low across Iowa. .LONG TERM...(Sunday through Friday) Issued at 321 PM CDT Fri Jul 9 2021 The next chance for organized thunderstorms development appears to be Tuesday night but the models have slowed the arrival of an upper level disturbance moving through the nrn Plains by perhaps 6 hours. This disturbance would present the best thunderstorm chances Tuesday evening and overnight across SD and nrn Nebraska. Winds aloft at h500mb-300mb increase to 30 to 50kts, dew points rise into the lower 60s and the GFS suggested precipitable water around 1 inch ahead of the storms. Chance POPs are in place for this system with the best rain chance across nrn Nebraska. Otherwise, the forecast is dry except for isolated thunderstorm chances. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 629 PM CDT Fri Jul 9 2021 The main weather concern over the next day will be the potential for thunderstorms across all of western and north central Nebraska. Thunderstorm development is currently ongoing across the Panhandle and will track south and east over the remainder of the evening and overnight. Some of these storms will have the potential for very large hail, damaging winds, and locally heavy rainfall. Visibility restrictions will likely occur at both sites this evening. Rain showers will continue into Saturday morning with some patchy fog as well. Additional restrictions down to 4 miles may be possible due to fog. Conditions will slowly improve by Saturday afternoon returning to VFR at KLBF by late afternoon. Ceilings remain near 4000 feet at KVTN through the afternoon. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...CDC LONG TERM...CDC AVIATION...Kulik
Area Forecast Discussion...Updated
National Weather Service Saint Louis MO
1057 PM CDT Fri Jul 9 2021 .UPDATE... Issued at 1057 PM CDT Fri Jul 9 2021 Although severe thunderstorms have been the primary concern so far this evening, this threat will be joined by/transition to flash flooding overnight into Saturday morning. Recent convective trends suggest that, in addition to the current Flash Flood Watch area, flash flooding will be possible in central MO as back building and training of thunderstorms becomes increasingly likely along the western flank of the MCS currently surging southward across the CWA. There is also potential for the maturing upstream MCS across eastern NE to traverse this area Saturday morning. As such, the Flash Flood Watch has been expanded to include portions of central MO and has been extended in time until 18z Saturday. Pfahler && .SHORT TERM... (Through Late Saturday Night) Issued at 354 PM CDT Fri Jul 9 2021 The synoptic setup this evening reminds me a bit of July 19, 2006 or June 28, 2018...although there are differences which may mitigate some of the worst of those two events. First, while there is a lot of CAPE available for convection to feed on this evening (2000-3500 J/Kg) MUCAPE, there isn`t as much as was available on either of the other cases. Second, I believe the 0-3km and 0-6km shear values were stronger in both of the previous cases. All that being said, I don`t think the MCS tonight will be as strong as in the older cases, but there still certainly a threat for winds of 60-70 mph, large hail, and a few tornadoes with the 0-1km shear rising to around 20-25kts after 04Z. There remains some question on timing and the exact track of the MCS. The most likely scenario is that storms over Iowa will strengthen as the low level jet strengthens this evening. Discrete convection should congeal into an MCS as the storms interact with one another, and the resulting MCS will dive southeast, paralleling the Mississippi River. In fact, the outflow boundary left from the supercell that went through Des Moines earlier may be where storms initiate on the low level jet. With that in mind, the most likely timing for severe convection will be from late evening into the early overnight hours...maybe 02Z to 08Z. The severe threat will likely transition to a flash flood threat after 06-08Z. WPC QPF shows 2+ inches of rainfall across parts of northeast Missouri and west central Illinois through Saturday morning, and there will almost certainly be higher amounts in locations that get more than one heavy thunderstorm. Saturday`s convection will depend heavily on what ultimately happens tonight. Present indications are that after tonight`s MCS exits the region, there will be enough diurnal heating and destabilization for another round of severe thunderstorms...mainly along and south of I- 70 during the afternoon and evening. Deep layer shear isn`t that impressive at 25-30kts, but RAP forecast SBCAPE values climb back up above 3000 J/Kg over southeast Missouri Saturday afternoon. The initial round of thunderstorms on Saturday afternoon/evening will likely stabilize the atmosphere enough to limit the severe threat, but showers and storms will likely continue overnight as a strong upstream shortwave dips into the lower Missouri Valley and cuts off over northwest Missouri. Carney .LONG TERM... (Sunday through Next Friday) Issued at 354 PM CDT Fri Jul 9 2021 Briefly for Sunday through next Friday... Medium range guidance shows the cut off low over northwest Missouri spinning in place until Monday when it begins opening up and drifting east-northeast. Scattered showers and thunderstorms will likely continue across the area at least through Monday while this low is in the vicinity. Temperatures Sunday and Monday are expected to be below normal with highs struggling to reach the mid 70s to low 80s across most of the area. The pattern becomes more zonal by late Tuesday in the wake of the low with a weak upper level trough developing over the Midwest by late Wednesday. This pattern will keep unsettled weather and a chance for thunderstorms each day through the end of the period. Temperatures should also warm back up toward seasonal normals as the pattern becomes zonal by late Tuesday. Carney && .AVIATION... (For the 00z TAFs through 00z Saturday Evening) Issued at 658 PM CDT Fri Jul 9 2021 Thunderstorms remain the primary concern through this TAF period, with their evolution and resulting timing still considerably uncertain. Latest expectation is for thunderstorms to develop across IA and northern MO this evening and move southeastward near the Mississippi River overnight into early Saturday morning, leading to greatest chance of impacts at KUIN and St. Louis metro terminals. These impacts include heavy rainfall reducing visibilities and strong wind gusts. Timing of these thunderstorms will likely need to be fine tuned by amendments as convective evolution becomes more clear over the next few hours. Showers, possibly a thunderstorm, could linger into Saturday morning along with formation of MVFR stratus over all terminals for at least a period during the morning. The southern edge of stratus will likely erode by afternoon with improvement to VFR flight conditions anticipated at KCOU, KJEF, and St. Louis metro terminals. Showers and thunderstorms are expected to redevelop Saturday afternoon, with the lowest chances of precipitation at KUIN reflected by only mention of VCSH at this juncture. Pfahler && .PRELIMINARY POINT TEMPS/POPS... Saint Louis 70 83 69 82 / 80 90 90 70 Quincy 68 77 66 75 / 80 80 80 70 Columbia 71 82 66 76 / 70 80 80 60 Jefferson City 72 84 68 78 / 50 80 90 60 Salem 67 84 69 83 / 60 90 90 80 Farmington 69 86 66 83 / 50 90 90 70 && .LSX WATCHES/WARNINGS/ADVISORIES... MO...Flash Flood Watch through Saturday afternoon for Audrain MO- Boone MO-Callaway MO-Cole MO-Gasconade MO-Knox MO-Lewis MO- Lincoln MO-Marion MO-Moniteau MO-Monroe MO-Montgomery MO- Osage MO-Pike MO-Ralls MO-Shelby MO-Warren MO. IL...Flash Flood Watch through Saturday afternoon for Adams IL-Brown IL-Pike IL. && $$ WFO LSX
Area Forecast Discussion
National Weather Service Memphis TN
935 PM CDT Fri Jul 9 2021 .UPDATE... Convection continues to die off in the region due to the loss of daytime heating. Don`t expect much coverage during the overnight period, but will continue to keep an eye on convection that is occurring across Northern Missouri. Latest HRRR shows this convection staying to the north of the Mid-South through the remainder of the night. Will keep chance POPS near the AR/MO and KY/TN state borders in case the convection gets further south than anticipated. Made some minor temperature and sky conditions tweaks as well. KRM && .DISCUSSION... /issued 256 PM CDT Fri Jul 9 2021/ Thunderstorms with heavy rainfall dot the area this afternoon most numerous near a weak surface boundary. These storms are expected to continue with localized flash flooding possible into the evening hours. Looking for convection to wane for Saturday before an upper low moves into the center of the country. This feature will force more numerous storms across the region Saturday night and Sunday. Our forecast area is outlooked for excessive rainfall and severe weather over this time period. A flash flood watch may be needed. Later forecasts will better address the time and location of the heaviest rainfall potential and the need for a watch. The upper low lifts out by mid-week, leading to a progressive westerly flow across the northern tier of the US. Temperatures will rebound while the threat for diurnal storms continues. Temperatures due to the convection are tricky. Max temperature readings under the upper low will hold in the 80s Sunday into early next week. Belles && .AVIATION... SHRAs/TSRAs have lifted north. Leftover light rain invof KMEM is quickly dissipating. Expect VFR conds overnight. Could see some SHRAs develop as the LLJ increases later tonight but confidence is low. SW winds will increase Sat AM to 10-14 kts with higher gusts...mainly across the Delta. Expect scattered SHRAs/TSRAs to develop with surface heating by Sat aftn. SJM && && .MEG WATCHES/WARNINGS/ADVISORIES... AR...None. MO...None. MS...None. TN...None. && $$
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
655 PM CDT Fri Jul 9 2021 .UPDATE... Issued at 655 PM CDT Fri Jul 9 2021 Precip in south central MN diminished quickly during the late afternoon, but the next round looks to be developing in northeastern SD and southeastern ND now. This should clip west central into south central MN late tonight into Saturday morning, with other potential for some development as well. Also updated for aviation discussion below. && .SHORT TERM...(This evening through Saturday night) Issued at 323 PM CDT Fri Jul 9 2021 A fairly robust line of showers and thunderstorms oriented northwest to southeast across south central MN is being supported by modest moisture advection/convergence and an elongated ribbon of vorticity across the Upper Midwest. Radar estimates 2 to 3 inches have fallen in some locations south and west of Mankato and there could be some minor flooding during the next couple hours. The intensity seems to be waning somewhat, so no Flash Flood Watches are being issued. This area of convection will slide to the southeast through the rest of the afternoon, likely organizing into a severe MCS across Iowa this evening. Convective development is a bit uncertain north of the MCS tonight. Consistency between CAM runs has been poor but the HRRR is not handling the current convection well at all. There does seem to be a trend toward a wetter solution along and west of the Mississippi River overnight into Saturday, particularly with the global models. A mid level trough will dig and become more negatively-tilted late tonight across the Upper Midwest, with a deformation zone developing north of the mid level low across central/southern MN. Pwats remaining in the 1.5-1.75 inch range, along with some modest CAPE and some low level forcing should allow additional convection to develop overnight. The Iowa MCS will dive southeast into eastern MO quickly later this evening and should leave little or no impact on subsequent development here. PoPs have been increased to high chance/low likely range west of the MS River. The showers and storms will be slow moving and could result in locally heavy rainfall. The upper low will continue to dig and eventually cut itself off from the prevailing flow late Saturday. It will sag south slowly through the day and take the deep moisture with it, resulting in diminishing PoPs from north to south into Saturday evening. .LONG TERM...(Sunday through Friday) Issued at 323 PM CDT Fri Jul 9 2021 Mainly dry weather is expected for the latter half of the weekend and into early next week, as any precipitation remains tied to the cutoff low south of the area over the mid-Mississippi valley. Light rain associated with the northern edge of the precipitation shield could briefly reach into the I-90 corridor Sunday and portions of west-central Minnesota Monday as the system begins to depart eastwards, but dry weather is expected overall. Dry easterly flow to the north of the surface low will keep temperatures seasonable and dew points comfortable, with highs in the upper 70s to low 80s generally expected. Widespread precipitation chances return midweek, as most models depict a shortwave tracking along the international border into the region. While most guidance has a system midweek, there remains a good deal of uncertainty remaining the timing and track of this system, including whether precipitation is favored over northern or southern portions of Minnesota and WI. Will stick with the general 20-30% PoPs from the NBM Tuesday through Thursday given the model discrepancies, although much of that time frame will likely remain dry. GEFS/EPS ensemble anomalies do not show much in the way of precipitable water anomalies next week, so any precipitation we get would likely be of the beneficial variety with widespread heavy rain or flooding appearing unlikely. Temperatures and dew points will increase midweek as low-level southerly flow develops, highs in the mid to upper 80s and dew points approaching 70 look likely. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 655 PM CDT Fri Jul 9 2021 Main issue is the possibility of MVFR ceilings later tonight and Saturday. East to southeast winds will prevail as a surface low in Nebraska moves into Iowa Saturday morning. MVFR conditions now in northwest Iowa will likely expand into southwest and south central MN. Said ceilings may develop farther and north, but it is rather uncertain whether MVFR will reach TAF sites from KAXN to KMSP and KEAU. If it does, it would likely occur for only a few hours. Otherwise, showers and storms in northeastern SD at this time may reach southwest and south central MN late tonight. KMSP...Kept a few hours of MVFR ceilings Saturday morning, currently from 10Z-15Z. This is uncertain, but it would be the favorable time for expansion of any MVFR from south central MN per short term models. Otherwise, think showers Saturday morning will remain southwest of KMSP, but this will need to be watched. /OUTLOOK FOR KMSP/ Sun...VFR. Wind NE 5-10kts. Mon...VFR. Slight chance MVFR/SHRA. Wind NE 5-10 kts. Tue...VFR. Slight chance MVFR/SHRA. Wind SW 5-10 kts. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...None. WI...None. && $$ UPDATE...TDK SHORT TERM...Borghoff LONG TERM...ETA AVIATION...TDK
Area Forecast Discussion
National Weather Service Spokane WA
348 PM PDT Fri Jul 9 2021 .SYNOPSIS... The region will remain dry into next week with periods of breezy winds at times. Temperatures will climb back into the upper 90s and low 100s by Saturday, and remain above normal well into next week. && .DISCUSSION... Tonight through Sunday night: The weather will be dominated by hot, dry and occasionally breezy conditions. There will also be some smoke mixed in, which could reduce visibility over some of the eastern third of WA and the ID Panhandle. First high pressure has been building in through today and it will be damped later tonight into this weekend by a couple shortwave troughs moving in from the Pacific. (The first is approaching the Vancouver Island/northwest WA). Look for some afternoon cumulus around the mountains, but little risk for precipitation. Milder air pumping in ahead of these features will bring some hot weather, especially Saturday. A heat advisory remains in place for Saturday for a good portion of the CWA. It cools a little bit on Sunday, but not by much. Winds will be on the rise with these passing features as well, largely for Saturday afternoon and evening and again Sunday afternoon and evening. Gusts in the 15-30 mph range will be possible. Combined with some low RH values this will lead to some fire weather concerns near the Cascade gaps. (See the Fire Weather section below for details on the Red Flag Warning.) Before those winds pick up and as that first trough is approaching, winds will turn more southeast to easterly tonight into early Saturday. This is projected to draw smoke near the Blue Mountain and Camas Prairie wildfires over more of our region. HRRR and other model guidance is in decent agreement in this evolution. However the bigger threat of reduced visibility (less than 6 miles) will be closer to the wildfires: such as the Blue Mountains, L-C Valley. Camas Prairie and into the Palouse. But it is also expected to spread toward northeast WA and northern Panhandle, though the first north you travel they less the coverage is expected to be. The winds start to return to a more westerly flow later Saturday into Saturday night. So for most of the area, the smoke is not expected to be a long lasting thing. The exception will be closer to the wildfires, i.e. near and east of the Blue Mountains and lower ID Panhandle. /Cote` Monday through Thursday: From a big picture standpoint, the Northwest will be under primarily zonal flow aloft this week with a few shallow shortwaves passing through. Monday afternoon and evening may bring showers and thunderstorms to our northern zones and especially the northern Cascades. Tuesday, Wednesday, and potentially Thursday bring additional shower and thunderstorm chances for much of the area with highest chances near the mountains. A lot of our area probably won`t see a wetting rain this week, but breezy winds are in store for Wednesday and Thursday. Otherwise, temperatures will generally reach into the 90s with low 100s possible in the Moses Lake area and Okanogan and LC Valleys. Thursday temperatures possibly cool to the upper 80s but likely remain in the 90s for the warmer spots. Skies will be mostly clear for the majority of the week except for areas impacted by wildfire smoke. Wednesday and Thursday are of concern for increased fire danger due to breezy winds and fire starts from lightning. RC && .AVIATION... 00Z TAFS: Mostly dry and VFR conditions with high pressure building in. The main caveat will be wildfire smoke. Wildfires near toward the lower ID Panhandle and Blue Mountains is expected to expand later today into Saturday, potentially bringing MVFR conditions near KLWS and KPUW. Closer to the fires themselves some IFR vis are possible. Some is expected to push toward KGEG/KSFF/KCOE toward Saturday morning, but the potential that it will drop visibility to MVFR conditions is not certain. Winds start to pick up Saturday afternoon. RC/Cote` && .FIRE WEATHER... Critical fire weather conditions from wind and low humidity are expected in the lee of the Cascades late Saturday afternoon into Saturday evening. Temperatures on Saturday will warm into the upper 90s to lower 100s while humidity levels dip near 10 percent. Northwest winds will increase in the afternoon and become strong near or shortly after 5PM. The winds will be capable of rapidly spreading any existing or new ignitions. Gusty winds will also fan out on to the Waterville Plateau, Saddle Mountains, and into the Moses Lake Area in the evening resulting in westerly wind gusts up to 30 mph. && .PRELIMINARY POINT TEMPS/POPS... Spokane 60 97 60 95 61 96 / 0 0 0 0 0 0 Coeur d`Alene 57 96 59 93 59 95 / 0 0 0 0 0 0 Pullman 56 94 55 91 55 92 / 0 0 0 0 0 0 Lewiston 64 104 67 101 65 102 / 0 0 0 0 0 0 Colville 54 97 55 96 55 97 / 0 0 0 0 0 0 Sandpoint 52 93 53 92 54 92 / 0 0 0 0 0 0 Kellogg 63 93 64 90 63 92 / 0 0 0 0 0 0 Moses Lake 59 100 59 98 60 99 / 0 0 0 0 0 0 Wenatchee 68 98 64 96 65 98 / 0 0 0 0 0 0 Omak 63 101 63 99 65 101 / 0 0 0 0 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...Heat Advisory from 11 AM to 8 PM PDT Saturday for Lewis and Southern Nez Perce Counties-Lewiston Area. WA...Heat Advisory from 11 AM to 8 PM PDT Saturday for Lower Garfield and Asotin Counties-Moses Lake Area-Northeast Blue Mountains-Okanogan Valley-Spokane Area-Upper Columbia Basin- Washington Palouse. Red Flag Warning from 2 PM to 11 PM PDT Saturday for East Washington Central Cascade Valleys (Zone 677)-East Washington South Central Cascade Valleys (Zone 676). && $$
Area Forecast Discussion
National Weather Service Norman OK
1053 PM CDT Fri Jul 9 2021 ...New AVIATION... .SHORT TERM... (This evening through Saturday) Issued at 328 PM CDT Fri Jul 9 2021 An isolated shower or two may affect SE portions of the fa this afternoon but the current forecast remains dry (below 15% chance). Models show showers and storms moving across portions of KS tonight. Can not completely rule out some of this activity sneaking into parts of far northern OK early Saturday, but will keep the forecast dry for now. Breezy S to SW winds are expected again Saturday ahead of a cold front. A surface boundary is expected to start coming through northern Oklahoma Saturday afternoon with a lagging upper level system during the evening/overnight hours. Both ample moisture and instability could potentially result in severe thunderstorms across much of our area. Expecting the surface boundary trailing along an elongated area of low surface pressure extending from eastern Kansas into Iowa. All models begin pushing the boundary into northern Oklahoma early Saturday afternoon. Ahead of this system under hot sunny skies, diurnal heating along the surface boundary may erode the inversion cap across northern Oklahoma as the afternoon progresses, while so far the models maintain the cap across the rest of our forecast area at least through Saturday afternoon. With surface based CAPE values of 2000-3000 J/kg, moderate to strong instability could result in severe convection developing toward late afternoon across northern Oklahoma should the cap break, which would be likely with the surface boundary coming through. DCAPE values would be sufficient for damaging wind gusts along with large hail would be the two severe hazards. The consensus from the latest CAMs run starts breaking out convection toward late afternoon across northern Oklahoma, with both the HRRR & NAM Nest members being the most aggressive. As a result, will maintain POPs across northern Oklahoma for Saturday afternoon. However, will need to monitor the timing of the surface boundary into our north as well as the afternoon cap strength across the rest of our area, especially across central Oklahoma. && .LONG TERM... (Saturday night through next Thursday) Issued at 328 PM CDT Fri Jul 9 2021 By Saturday evening, the upper low across the Central Plains/Midwest will start digging a positively tilted trough into the Southern Plain, as our northwest flow aloft will be increasing. Models start to differ with the location of the surface boundary/front, with the NAM & Canadian NH bringing it down into central Oklahoma along the I-40 corridor, while the GFS & ECMWF keep it hung up and stretched across northern Oklahoma. With the upper trough and surface boundary in place, will expect to see convection become more widespread through the evening hours. The severe risk will remain even ahead of the front where moderate elevated instability from steep mid-level lapse rates could result in strong to severe fast moving high-based storms. However, expecting the severe risk to be the highest near the surface front across central and northern Oklahoma with the more slower moving cells. Large hail and severe wind gusts will remain the primary hazards. However, with PW values approaching 2-inches across northeastern Oklahoma, can`t rule out an additional hazard of flash and river flooding from heavy rainfall across eastcentral through southeast Oklahoma. After midnight into the early morning hours of Sunday, expecting northern Oklahoma to be dry with the storm POPs generally east and south of the I-44 corridor where the front should be. With strong ridging persisting across the western U.S. and Eastern Seaboard, long-range models block the upper low across the Midwest, maintaining troughing across the central U.S. including the Southern Plains into Monday. With the surface boundary lingering across our south along with some mid-level vorticity disturbances rounding through the trough, will restrict low POPs across southeast and far southern Oklahoma and north Texas for Sunday, although not expecting any of these storms to be severe. Although the surface boundary should be washed out by Monday, additional mid-level disturbances will keep low POPs across our far south for one more day. By Tuesday, expecting the ridge across western Oklahoma to build further east across our area maintaining dry conditions. However, we`ll start seeing a strong return of south winds under the ridge and start warming up more seasonably average into the lower to mid- 90s. By mid-week, the ridge starts breaking down with weak troughing coming down from the north. As a result, could see storms return across our north through the latter half of next week. && .AVIATION... (06Z TAFS) Issued at 1051 PM CDT Fri Jul 9 2021 Still expect MVFR stratus late tonight thru Saturday morning for most terminals. Wind speeds will remain around 10 to 15 kt from the south overnight, and then shift slightly to the SSW and eventually northwesterly behind a cold front Sat night. Thunderstorms will accompany the front after 21Z through the overnight Sat, especially across central and northern OK. && .UPPER AIR... Issued at 1207 PM CDT Fri Jul 9 2021 An Upper Air flight is currently planned for 12Z and 20Z Saturday along with 0Z Sunday. && .PRELIMINARY POINT TEMPS/POPS... Oklahoma City OK 90 72 90 69 / 0 0 10 60 Hobart OK 93 72 94 69 / 0 0 10 40 Wichita Falls TX 92 73 95 72 / 10 0 0 50 Gage OK 96 73 93 66 / 0 0 20 10 Ponca City OK 93 73 89 66 / 10 10 60 40 Durant OK 90 74 91 74 / 10 0 10 70 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...None. TX...None. && $$ SHORT TERM...10 LONG TERM....68 AVIATION...03
Area Forecast Discussion...UPDATE
National Weather Service Portland OR
808 PM PDT Fri Jul 9 2021 Updated Aviation and Marine discussions .SYNOPSIS...Persistent upper high pressure near the Four Corners area will move slowly west through the weekend, while onshore flow at the surface keeps the max temperatures moderated. Readings will continue to be 5 to 10 degrees warmer than normal for mid-July, with dry conditions expected for the next week. An upper low will begin to slowly press down from the Gulf of Alaska to cool temperatures back down towards normal for mid-week next week. && .SHORT TERM...This evening through Monday...Many of the models are in consensus that the shortwave ridge, which brought warmer-than- average temperatures across most of the CWA today, will be meandering east in advance of a weak impulse that is expected to cross the region late this evening. While this area of 500mb positive vorticity is not going to lead to CWA-wide precipitation, it will promote an increased pressure gradient oriented to favor onshore flow. This will form a decent flux of marine stratus both along the coast and well into the Willamette Valley (through the Gorge and Coast Range terrain gaps). In addition, the potential for light drizzle along the coast is nonzero where the RAP and NAM are actually depicting a small amount of QPF. At this time, elected to leave the mention of drizzle out of the forecast as some forecast soundings suggest the marine layer will be relatively shallow at less than 2500 feet. This will be a point of consideration for possible adjustments to the forecast in future shifts. Tomorrow will be another warm day largely thanks to a slightly weaker marine push overnight tonight compared with yesterday. High temperatures will not be quite as warm as today with highs generally 2-5 degrees (F) cooler as the ridge`s axis will have shifted east of our area. Westerly gusts to 25-30 mph are very possible along the central Oregon coast, southern Willamette Valley downwind of Coast Range gaps, and along the Columbia River Gorge (especially east of Troutdale). Similar to Saturday, Sunday will feature morning stratus and will be several degrees warmer than normal under weak ridging/zonal upper-level flow. Will likely see afternoon breezy winds. -Bumgardner .LONG TERM...Monday through Friday...The deterministic GFS and CMC portray a kink in the predominantly zonal flow aloft rippling across our area Monday, while the ECMWF has the feature further north. Depending on the timing of the feature, this could favor an enhanced marine push to yield more stratus and hence cooler high temperatures Tuesday. There is also a chance for drizzle on Monday but decided to leave out of the forecast at this time due to a lack of model agreement in both the timing and strength of the feature. By Tuesday models begin diverging significantly. The GFS shows a shortwave ridge attempting to build between the exiting trough and another incoming shortwave trough. The CMC has a similar shortwave ridge amplifying just to our east in central and eastern Oregon/Washington, and the second shortwave trough crossing our area Tuesday afternoon. The ECMWF has our area in southwest flow with a stronger, and a larger-scale upper level cutoff low spinning far to our northwest in the eastern Gulf of Alaska. Thankfully, these discrepancies are relatively minor, with most solutions from the WPC`s cluster analysis suggesting a generally zonal synoptic-scale weather pattern across the PacNW. While uncertainty is high at this time for the end of the long-term period, the probability of consequential precipitation appears low. -Bumgardner && .AVIATION...At 0300Z satellite imagery shows SKC conditions across most of the forecast area while IFR marine stratus along the coastline is beginning to push back onshore. Expect VFR conditions to prevail for inland area through at least 08Z Saturday. High resolution model low cloud guidance shows marine stratus pushing up the Columbia River in Cowlitz County overnight with about a 50 to 60 percent chance IFR to low-end MVFR cigs develop in portions of the Willamette Valley between 12Z and 14Z, primarily in the Portland metro area east of Interstate 5 and also between KEUG and KS12. IFR stratus will deepen at coastal areas this evening then spread into the coastal valleys overnight. Areas from KONP to K6S2 may remain IFR through 19Z Sat. Brief VFR conditions may be possible along the coast by Sat afternoon but will likely be mixed with low end MVFR stratus. For detailed regional Pac NW aviation weather information, go online to: KPDX AND APPROACHES...VFR to prevail through at least 12Z Sat. There is about a 50 percent chance low-end MVFR conditions develop at the terminal and vicinity around 13Z Sat. VFR conditions are expected again by 17Z Sat. /DDH && .MARINE...The typical summer regime continues for the next several days. Surface high pressure will remain anchored over the eastern Pacific. A thermally-induced surface trough will reside along the north California and south Oregon waters for the next several days. This results in northerly wind over the coastal waters, strongest during the afternoon and evening hours each day. The latest model guidance suggests wind gusts to 25 kt over the central and northern waters through late tonight. There looks to be a brief break in small craft advisory level wind speeds Saturday morning. The 12Z model guidance shows 25 kt gusts developing over PZZ255 and PZZ275 by early Sat afternoon and then spreading into the south half of PZZ270 around mid-afternoon. Will issue a new round of small craft advisories with this forecast. The 12Z models suggest wind speeds ramp up a little more Sunday afternoon, with small craft advisory conditions covering a larger portion of PZZ270. Gusts 25-30 kt expected over a majority of the waters Sun afternoon through early Mon. The strongest gusts will be in PZZ255 and PZZ275. Wind speeds ease Tuesday night and Wednesday as the pressure difference weakens and the marine layer deepens. Wave heights will remain below 10 feet for the next several days. There will be a considerable wind wave or fresh swell component, with a low-amplitude but long-period background southwest swell. The fresh swell component builds into the 5 to 7 foot range around the middle of next week. Weishaar/DDH && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...Small Craft Advisory until 11 PM PDT this evening for Coastal waters from Cascade Head to Florence OR out 10 NM-Waters from Cape Shoalwater WA to Cascade Head OR from 10 to 60 NM. Small Craft Advisory from 2 PM Saturday to 2 AM PDT Sunday for Coastal waters from Cascade Head to Florence OR out 10 NM- Waters from Cape Shoalwater WA to Cascade Head OR from 10 to 60 NM. Small Craft Advisory until 3 AM PDT Saturday for Waters from Cascade Head to Florence OR from 10 to 60 NM. Small Craft Advisory from noon Saturday to 5 AM PDT Sunday for Waters from Cascade Head to Florence OR from 10 to 60 NM. && $$ Interact with us via social media:
National Weather Service Raleigh NC
945 PM EDT Fri Jul 9 2021 .SYNOPSIS... A trough of low pressure will move offshore tonight. This will be followed by drier weather overnight into Saturday. A more typical summer-like pattern is expected from Sunday into next week with near normal temperatures and chances of afternoon thunderstorms. && .NEAR TERM /THROUGH TONIGHT/... As of 945 PM Friday... The line of showers/storms was pushing offshore with plenty of high and mid cloudiness left behind over central and western NC. THe latest satellite data indicated the high clouds were thinning and scattered from the west. Upstream, there continued to be partly cloudy skies, thus our forecast will likely become partly cloudy in all areas overnight. Probabilities of some ground fog are higher in the central and east where the soils are wet. However, the scattered clouds and slightly drier air in the lower and mid levels working in from the west - northwest should keep the fog from being widespread. Lows were dropped a bit in the NW given this information (with upper 60s there) ranging into the lower to mid 70s SE. Previous update at issued 545 PM today... We have had several Severe Thunderstorm Warnings this afternoon into the early evening. These storms have been producing marginal severe winds (highest reports in the 45 mph range). These winds combined with the saturated ground have topped more trees than would normally have fallen in a less saturated period. Most of the instability is now along and south/east of the numerous outflow boundaries, mainly along and ahead of the initial line of storms now extending from Laurinburg to Fort Bragg to Smithfield and Wilson. The storms over Raleigh are elevated and in the rain cooled air and producing heavy rain and winds to 30 mph. Another line along a wind shift boundary over the NW Foothills may organized for a few hours as it moves into portions of the Triad. These should remain below severe limits (gusts to 40-45) and in a area that had less rain yesterday. Previous discussion as of 208 PM Friday... Early afternoon water vapor and vis satellite imagery reveal an approaching longwave trough along the Appalachian Mtns, with a developing cu field across the central Piedmont. Showers and thunderstorms have re-developed within the lee trough across western NC and VA, and have expanded in coverage as they`ve descended from the higher terrain into an environment supportive of deep convection. Latest SPC/RAP mesoanalysis suggests around 1500 J/KG of ML instability across the region with upwards of 2000 J/KG across the Sandhills. Surface dewpoints ahead of the approaching trough remain in the mid 70s in the wake of TS Elsa and while PW`s are lower than they were yesterday, they are still above normal for early July around 1.7 inches. Last few runs of the HRRR as well as the 12Z HREF have captured current convective trends quite well, indicating a broken line of convection moving through the area between now and 00-02Z with intensification taking place as the storms move just east of the Triad into the axis of peak instability. While the overall severe threat is low (owed primarily to weak deep shear only around 15- 20kts), the strongest storms will be capable of gusty winds that could approach severe limits. As the convection continues moving east into the late afternoon, instability will eventually wane with the loss of daytime heating and the line should begin dissipating as it makes its way through the Coastal Plain. Brief periods of heavy rain will also accompany the line but should not lead to significant flooding issues. Following the convective line, the longwave trough will drag a boundary (or a very weak front, if you can even call it that) through the area this evening. Some hi-res guidance is indicating some secondary development along this boundary but the atmosphere should be sufficiently overturned by that point to keep anything from lasting too long. Thus I will keep the forecast dry this evening. Temperatures and dewpoints tonight behind the boundary will be very similar to what was seen this morning. Lows bottoming out in the lower 70s with dewpoints thereabouts as well. Patchy fog is possible tonight especially in locations that see rainfall this afternoon but not an idealized setup for widespread dense fog. && .SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/... As of 100 PM Friday... Saturday will start off dry with large scale subsidence across the Piedmont. Meanwhile, an upper low will move from the upper Midwest into IA/MO Saturday afternoon, pushing a weak boundary through through the OH valley and into western VA/NC in the process. Forecast profiles do not look overly supportive of precipitation tomorrow given dry air and subsidence aloft but a few isolated showers could develop east of the mountains within the lee trough during the afternoon hours. Very low PoPs look more than sufficient for tomorrow afternoon with dry weather forecast for the evening/overnight hours. Temps will be within a degree or two of normal with highs around 90, lows in the lower 70s. && .LONG TERM /SUNDAY THROUGH FRIDAY/... As of 345 PM Friday... The extended period will generally feature a typical summertime pattern for central NC, with diurnal showers and storms each afternoon and evening, quickly dissipating after sunset, and no real frontal passages to speak of. The best chance of showers and storms comes on Sunday, thanks to deep moist southerly return flow off the Atlantic around both an upper low centered over IA/MO and a western Atlantic ridge. The 12z GFS has precipitable water values near or in excess of 2 inches over much of the area. Thus have chance POPs in the east increasing to likely in the west where the best moisture and instability will be. 0-6 km flow still looks too weak for any organized severe storm threat. As the center of the Bermuda high drifts farther west closer to our region, subsidence and weaker moisture advection will then result in decreasing shower and storm chances through midweek. Chance POPs on Monday give way to the lowest POPs of the period on Tuesday and Wednesday (slight to low chance), again highest in the western Piedmont which will be farthest from the center of the ridge. The GFS and its ensembles are farther west with the Atlantic ridge and thus especially dry compared to the ECMWF. By Thursday and Friday, as the next upper trough and associated cold front move through the Upper Midwest, they will act to weaken the ridge and push it SE, with a strengthening lee surface trough over the Piedmont. Thus shower and storm chances should begin to increase again, but POPs stay around 30-40% as there will continue to be a lack of any forcing mechanisms. High temperatures will be close to normal through the period (upper- 80s to lower-90s), with Tuesday and Wednesday likely being the warmest days due to less clouds/precip. Enough clouds and moisture will be around to keep lows near to slightly above normal, in the upper-60s to lower-70s. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... As of 835 PM Friday... A return to VFR conditions was spreading east across the region as the thunderstorms have moved to our SE. There is a possibility of some patchy MVFR fog (RDU,RWI,FAY) late tonight. Any fog that develops will mix out quickly after sunrise. Outlook: Looking ahead, Saturday will see a weak boundary lifting north through the area but with large scale subsidence aloft, it looks to be a mostly dry day at the TAF sites. Sunday onward will see a typical summerlike pattern with VFR conditions and periods of sub-VFR diurnally driven convection. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Badgett/Leins NEAR TERM...Kren/Badgett SHORT TERM...Leins LONG TERM...Danco AVIATION...Badgett/Leins
Area Forecast Discussion
National Weather Service Reno NV
120 PM PDT Fri Jul 9 2021 .SYNOPSIS... Dangerous levels of heat are forecast for this weekend into early next week. Be sure to hydrate and limit outdoor activity during the afternoon hours. A few afternoon and evening thunderstorms are expected south of Highway 50 for the next few days. Smoke from the Beckwourth Complex fire will affect portions of extreme eastern California and western Nevada through at least the weekend. && .DISCUSSION... No appreciable changes to the forecast over the next week. The long-advertised very hot temperatures are imminent (and already started days ago out in Lovelock, Fallon, and Hawthorne) with today starting the ramp up to the peak temperatures expected between Saturday and Monday. Heat * High pressure peaking at 598-600 DM heights will build over CA/NV this weekend. These heights correlate to impressive heat for the region with 100 to 109 for lower valleys and upper 80s to mid 90s for mountain communities expected. At this time, reaching Reno`s all-time high of 108 only has about a 10-20% chance of happening with 700 mb temperatures in models peaking at near 19C (corresponds to 105-106). In any case, 105 versus 108 is unlikely to make much difference as it is still memorably hot! Best advice is to limit outdoor activities, stay hydrated, and check on those that are more susceptible to heat related issues. Knowing the signs of heat illness could save a life. Temperatures are expected to start easing down for the middle to latter portion of next week (to within a few degrees of average) as high pressure weakens with low pressure impinging on the Pacific Northwest. Thunderstorms * Isolated coverage is expected for Mono, southern Lyon, and Mineral counties each afternoon through at least Monday. Saturday could have more expansive coverage as far north as I-80 between the Virginia Range and Highway 95/Fallon. Gusty outflows 40-50 mph and lightning will be primary threats from storms. Storm chances may wane by Tuesday-Wednesday as stronger westerly flow pushes convergence for storms away from western NV and the eastern Sierra. Air Quality * Smoke associated with ongoing fires, like the Beckwourth Complex and Tennant Fire, will continue to stream across the region. Output from the HRRR smoke simulations still show increased chances that smoke from the Beckwourth Complex will settle farther southward than the last couple of days. This puts the Reno Metro in the area for at least some haze over the next day or so with some periodic degradation of air quality possible. However, the worst conditions will be in proximity to the Beckwourth Complex such as in Doyle and for areas east of there out towards Lovelock and Fallon. Eastern Modoc County and the Surprise Valley are likely see some decreases to air quality as well from the Tennant Fire. && .AVIATION... Very hot temperatures continue this weekend and into next week with density altitude concerns, particularly for smaller aircraft. The Sugar Fire within the Beckwourth Complex in Plumas County continues to burn actively with denser smoke expected in the morning hours through the Doyle-Pyramid Lake areas becoming more diffuse into Pershing and northern Churchill Counties. HRRR runs are even indicating a period Saturday morning from approximately 12z-16z where smoke may make it to around KRNO, but it doesn`t look overly dense. Mixing during the daytime hours will bring improved visibility outside of the areas immediately around the fire; however, slantwise visibility may still be slightly restricted. General haze is possible elsewhere due to other wildfires burning in the west. Afternoon westerly winds today and Saturday will generally be lighter than usual with peak afternoon gusts in the 15-20 kt range. We`ll see winds return to "usual" levels Sunday with gusts to around 25 kts and then there is potential for a slight uptick for the early part of next week. Isolated thunderstorms are possible this and Saturday afternoon/evening (approx 20z-03z), primarily near and south of I-80. Storms initiating in the Eastern Sierra may march north along the Pine Nut Range before being shifted east as the afternoon westerly winds kick in. Storms have the potential to bring localized heavier rain with lowering CIGS/VIS and terrain obscuration. The greatest concern, however, will be gusty and erratic outflow winds (40+ kts) from any storms that do develop. Outflows may travel well away from the parent thunderstorm and kick up dust across the west central Nevada Basin and Range. -Dawn && .FIRE WEATHER... * Hot-unstable conditions favor plume dominated fires which may lead to extreme fire behavior and rotating smoke columns for active fires through Monday. * Afternoon and evening thunderstorms possible today through Tuesday for the Eastern Sierra and Sierra Front into central Nevada. High pressure over the Desert Southwest and much of Nevada will lead to an extended period of hot-dry-unstable conditions into early next week. Minimum RH will remain in the single digits with poor recoveries overnight. This requires a heightened fire weather awareness over the next few days. Winds... Lighter than usual westerly afternoon winds are anticipated today and Saturday with peak gusts mainly in the 15-25 mph range. We`ll see more of a typical zephyr Sunday with speeds about 5-8 mph stronger. Further uptick in wind speeds are looking probable the early part of next week as the ridge diminishes a bit. The one exception to the lighter winds today and Saturday will be thunderstorm outflows. More details on that below. Thunderstorms & Active Fire Instability... A weak moisture push today and Saturday will lead to increasing thunderstorm chances, but storm chances will also be somewhat limited by the building ridge and subsidence aloft. Therefore, coverage should remain rather isolated and storms may not grow enough vertically to produce copious amounts of lightning with LALs in the 2-3 range as a general rule. Storms will be slow moving and with increased moisture could produce decent rainfall under storm cores. Of course, there is still a risk of a wet/dry hybrid situation with dry strikes igniting new fires. These storms have the potential to produce strong outflow winds in excess of 45 mph given the hot & dry surface conditions. Outflows may travel a significant distance away from the parent storm, with a 5-10% chance of affecting the Beckwourth Complex this or Saturday evening. Otherwise, activity looks to remain near and south of I-80, initiating in the Eastern Sierra before marching north along the Pine Nut Range. Storms will shift east after 4-5 pm as westerly winds kick in. The heat, instability, and some increase in mid-level moisture will help promote pyrocumulus development over active fires; opening the door for pyrocumulus column collapses. A few storms could linger into the start of next week, but coverage does look to decrease. -Dawn && .REV Watches/Warnings/Advisories... NV...Excessive Heat Warning until 9 PM PDT Monday NVZ001-004. Excessive Heat Warning from noon Saturday to 9 PM PDT Monday NVZ003-005. CA...Excessive Heat Warning from noon Saturday to 9 PM PDT Monday CAZ070-071. && $$ For more information from the National Weather Service visit...
Area Forecast Discussion
National Weather Service Blacksburg VA
959 PM EDT Fri Jul 9 2021 .SYNOPSIS... Drier air will filter in tonight. The chance for showers and thunderstorms return late tomorrow as a warm front arrives. The daily precipitation chances continue, but will mainly affect areas along and west of the Blue Ridge by Monday and Tuesday. A western Atlantic ridge builds back into the southeast by midweek. && .NEAR TERM /THROUGH SATURDAY/... As of 959 PM EDT Friday... ...Lowering humidity and clearing skies tonight with drier conditions settling in Saturday... Our weak frontal boundary from earlier this evening continues to move off to our east across eastern Virginia and North Carolina.High pressure over the Great Lakes region continues to slowly slide south into the Ohio River Valley ushering in lowering humidity, clearing skies, and calm winds overnight into the first half of Saturday. The combination of clear skies, light winds, and low level moisture in areas where showers may have passed through will lend it`s hand to a few pockets of patchy valley fog heading into Saturday morning. Highest confidence for fog looks to be across the Greenbrier Valley, North Carolina Piedmont, and Virginia Southside per latest guidance from both the HRRR and NAMnest. As for temperatures, expect lows to drop into the upper 50s and low 60s west of the Blue Ridge with low to mid 60s out east. Humidity will also drop off making for a relatively comfortable Saturday morning whether your out for a jog or at the local farmers market. Mostly sunny skies will be noted in most locations with cumulus likely to build up with the peak heating of the day along and west of the Blue Ridge. An isolated shower or storm can be expected in these locations, but per current 18Z guidance from NAMnest, GFS, and the latest NBM the bulk of any convective activity looks to remain well to our west across western West Virginia and eastern Kentucky where better forcing can be found along our next frontal boundary lifting in. High temperatures Saturday afternoon will range from the upper 70s in the mountains to lower 90s across the Piedmont. By Saturday evening, our warm frontal boundary will start to lift in as low pressure meanders over the central Plains region. Enough dry air should remain in place from high pressure to the north to hold any shower or storm activity west of the Blue Ridge. As a result, 30 percent PoPs will remain across our southern West Virginia counties where the best bet for convective activity remains. Once again coverage will be isolated to scattered at best. Storm coverage will decrease with the loss of heating heading into the overnight hours. Confidence remains high in the near term period on temperatures and precipitation chances. Moderate confidence in regards to fog. As of 730 PM EDT Friday... The afternoon convection associated with the prefrontal trough has pushed south and east of our area. This is supported by the HRRR,HiResw-ARW and NAMnest. Skies will begin to clear tonight as cumulus diminishes with the loss of solar heating. The combination of light winds and low level moisture will result in patchy fog overnight especially where it rained earlier and in the river valleys. The Greenbrier valley has the best chance for fog overnight. Adjusted temperatures utilizing the latest surface obs, their trends and blended in the NBM for this evening into tonight. Low temperatures overnight will be mild with readings from the mid 50s in the mountains to mid 60s in the piedmont. Low pressure moving through the central Plains Saturday will push will push a warm front north across our region. Scattered showers and thunderstorms will develop during the afternoon mainly in the west. High temperatures Saturday will range from the upper 70s in the mountains to the lower 90s in the piedmont. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/... As of 1250 PM EDT Friday... Daily chances of showers and storms with some strong storms possible Sunday into Sunday night... The forecast area Saturday night into Sunday night will be positioned about half way between the center of an upper high located off the coast of the Carolinas and a deepening upper low that will settle over the mid-Mississippi Valley. The location of these two features will help allow our region to experience increase moisture flow off the Gulf of Mexico all the while good surface heating takes place during the daylight hours. The Storm Prediction Center`s Day 3 Convective Outlook places a Marginal Risk of severe weather across mainly central and western parts of the region Sunday into Sunday night in association with expected convection. The heightened concern for severe weather potential coincides with a shortwave trough rounding the base of the mid-Mississippi Valley and heading northeast towards, or potentially across, parts of the southern Appalachians. Monday into Monday night, the relative positions of the upper low and upper high stay about the same except for some retrograde of the upper high towards the coast. Showers and storms will again be possible during the afternoon and evening, but with perhaps a bit less coverage as compared to Sunday. A slightly stronger cap aloft with the closer proximity of the upper high is to blame. Temperatures during this portion of the forecast are expected to be near, or slightly above, normal for this time of year. Confidence in the above weather scenario is moderate to high. && .LONG TERM /TUESDAY THROUGH FRIDAY/... As of 1210 PM EDT Friday... Through the period at or above normal temps with daily chances of afternoon/evening showers/storms mainly across the mountains... During this portion of the forecast high pressure will remain anchored off the coast of the Carolinas. This will help maintain a southwest flow across the region, tapping the Gulf of Mexico. This moisture will advect into the region. The degree to which there will be an upper level trough across the Ohio Valley will vary, with Tuesday, and then again on Friday, the time frame where the region may have a bit more upper level dynamics involved for the development of any showers and storms. Outside those two days, diurnal and differential heating will be the primary feature to help initiate convection, and the strength of the upper level high`s cap across the area will limit coverage. The best coverage is expected to be over the mountains, farther away from the center of the upper high, and closer to any influence a central U.S. upper trough may provide. Temperatures through the period are expected to at or slightly above normal. Confidence in the above weather scenario is moderate to high. && .AVIATION /02Z SATURDAY THROUGH WEDNESDAY/... As of 821 PM EDT Friday... The convection with the surface trough has pushed south and east of our region this evening. As high pressure builds south from the Great Lakes, drier air will filter in our region this evening into tonight. Afternoon cumulus will dissipate with the loss of solar heating this evening. This will allow skies to clear tonight. With winds becoming light and variable tonight, patchy fog will develop overnight. The taf sites with the best chances for fog are KLWB, and perhaps KBCB which received rain today. Sct to BKN VFR cumulus will develop Saturday afternoon into Saturday evening. Isolated MVFR storms are possible in the western mountains. Average confidence for wind, ceilings and visibility. Extended Aviation Discussion... Moisture increases Saturday evening into Saturday night on back side of surface ridge of high pressure and ahead of the next slowly approaching frontal system. Afternoon and evening MVFR shower and thunderstorm chances increase each day from Sunday into Monday. Some of the storms on Sunday in the mountains could be strong. For Tuesday and Wednesday, thunderstorms will be more confined to the mountains.The unsettled weather will continue for Thursday. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...ET/SH NEAR TERM...ET/KK SHORT TERM...DS LONG TERM...DS AVIATION...KK/SH