Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/08/20

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
910 PM CDT Sun Jun 7 2020 .UPDATE... Issued at 910 PM CDT Sun Jun 7 2020 Showers and thunderstorms, some severe, were lifting northeast across the cwa this evening. These will be lifting into north dakota tonight. Made adjustments to pops earlier. UPDATE Issued at 650 PM CDT Sun Jun 7 2020 00z aviation discussion updated below. && .SHORT TERM...(This Evening through Monday Night) Issued at 320 PM CDT Sun Jun 7 2020 Main concern in the near term is the potential for strong to severe thunderstorms late this afternoon and this evening as a cold front tracks across the area and encounter extreme instability. CAPE values of 3000-5000 J/kg will be common late this afternoon into the early evening hours. Bulk shear will increase into the 50 to 65 knot range along and ahead of the front, along with a low level jet increasing into the 50 to 70 knot range. This combination of factors will result in thunderstorm development, which looks to initiate around 22Z between the Missouri River and the James River Valley. The biggest question right now is whether these storms will take more of a northeast track as shown in the HRRR and the ARW, or if they line out and more more easterly as shown by the high resolution NAM and the NMM. There will be a bit of a stronger CAP over the southeastern part of the CWA, so for now, will lean toward the more northeasterly track solution and keep fairly low POPs across the east. Where the storms do develop, conditions will be highly favorable for them to go severe, with gusty winds and large hail the most likely threats. An isolated tornado or two cannot be ruled out due to the strong shear as well. May see some lingering showers across the far northeastern part of the CWA into the overnight hours. The frontal boundary stalls out over the far eastern CWA on Monday, but conditions during the day will be mainly dry with little else to support precipitation. By Monday night however, an upper trough will approach the region and will begin to meet up with the remnants of Tropical Storm Cristobal, and the stalled front looks to then become the focus for rainfall. The uncertain part now is just how far west this precipitation will reach, with some models keeping it east of the James River Valley, and others bringing it as far west as the Leola Hills region. Rainfall amounts in excess of 1 to 1.5 inches cannot be ruled out. Low temperatures tonight will range from the upper 50s northwest to the lower 70s east, with highs on Monday ranging from the mid 70s northwest to the lower 90s east. Lows Monday night will be in the 50s. .LONG TERM...(Tuesday through Sunday) Issued at 320 PM CDT Sun Jun 7 2020 The period begins on Tuesday with the remnant tropical system surging northwards into the Midwest. The storm system, along with a mid level trough passing through the region will bring showers and thunderstorms to the eastern half of the CWA. With a more stable environment, severe weather is not expected on Tuesday. Cooler, dry air will move into the region on Wednesday with boundary layer dew points in the mid 40s. The combination of steep low level lapse rates and some mid level moisture may result in isolated showers, mainly in the eastern CWA. Buffer soundings support gusty winds on Wednesday with a max gust of 30 to 35 knots. The rest of the long term will feature dry conditions with temperatures below, to near normal. Temperatures will be around normal on Saturday and Sunday with highs in the upper 70s, to the low 80s. && .AVIATION...(For the 00Z TAFS through 00Z Monday Evening) Issued at 650 PM CDT Sun Jun 7 2020 Terminals KABR,KATY,KPIR,KMBG Thunderstorms are expected to move from southwest to northeast across the region into the early morning hours. PIR and ABR are expected to be affected with possible MVFR vsbys and ceilings. Otherwise, expect VFR conditions for ATY and MBG for the entire period and after the storms pass, expect VFR conditions at ABR and PIR. ***Construction to improve the taxiway for runway 13 at the KPIR terminal may cause an occasional temporary visibility reduction due to blowing dust (bldu), mainly during daytime hours UFN. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. && $$ UPDATE...Mohr SHORT TERM...Parkin LONG TERM...SD AVIATION...Mohr
Area Forecast Discussion...Updated
National Weather Service Billings MT
839 PM MDT Sun Jun 7 2020 .UPDATE... Thunderstorm activity decreasing in intensity across the area and areas of stratiform precipitation beginning to fill in across south central Montana. Updated forecast to decrease thunderstorm probabilities. borsum && .DISCUSSION... Tonight through Monday night... Early this afternoon have started to see some thunderstorm development in the western zones. There have been some winds with these thunderstorms, but nothing of concern at the moment. The HRRR has not been as aggressive with the 80m winds as it had been on previous runs. However, still expecting strong winds to be the main threat. There could also be some hail, have already had a report of some pea-sized hail in the Beartooth Foothills. These storms should quickly move off through the evening. Overnight and through Monday night, still expecting the mountains to see some accumulating snowfall. Generally this will be above 6000 feet with the highest accumulations of over 6 inches above 8000 feet. This will still impact the Beartooth Pass. The rest of the area will see showers become scattered through the day. Temperatures will be cooler than normal for the whole area. Reimer Tuesday through Sunday... Weak shortwave in northwest flow aloft should have enough forcing for light mainly diurnal showers on Tuesday, especially in the east where coldest air aloft will be in the afternoon, though otherwise we will see drying on this day with precipitable waters falling under a half inch. W-NW winds will be well-mixed and breezy. Look for temps in the 60s. Building ridge from the west will bring a warmer and mostly dry day on Wednesday, but there may yet be enough energy for a few showers over the mountains/foothills. W-NW winds will again be breezy. Expect amplified ridge to bring warmer conditions Thursday through Saturday, with temps returning to the 80s if not lower 90s by the end of the week. As the ridge axis shifts east, southwest flow aloft and increasing high plains moisture will open the door to thunderstorm potential by the weekend. A deeper trof is possible by next Sunday or Monday, but plenty of model uncertainty this far in advance. JKL && .AVIATION... Areas of rain showers across the region with periods of MVFR along the foothills and mountain obscurations. KLVM and KSHR terminal sites with best odds of seeing MVFR. A few isolated thunderstorms possible. borsum && .PRELIMINARY POINT TEMP/POPS... Mon Tue Wed Thu Fri Sat Sun ----------------------------------------------------------- BIL 046/060 044/067 049/072 049/080 054/086 058/085 057/079 97/W 32/W 01/B 00/U 00/B 11/B 23/T LVM 041/055 036/064 045/070 044/079 049/084 053/082 051/073 79/T 40/N 12/T 00/U 01/B 12/T 34/T HDN 046/062 044/067 047/072 047/080 052/089 058/088 058/082 95/W 32/W 01/B 00/U 00/U 01/B 22/T MLS 050/063 046/065 047/070 048/078 052/085 060/085 059/082 94/W 32/W 00/N 00/U 00/U 11/B 22/T 4BQ 048/066 045/064 045/070 047/078 050/086 058/088 057/082 83/W 32/W 00/N 00/U 00/U 01/B 22/T BHK 049/066 044/064 044/069 046/076 048/081 055/082 055/078 72/W 22/W 00/N 00/U 00/U 01/N 22/T SHR 043/064 041/064 042/071 044/078 049/087 056/088 055/081 84/T 42/W 01/B 00/U 00/U 01/B 22/T && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...Winter Weather Advisory in effect until noon MDT Monday for the Beartooth Highway FOR ZONE 67. WY...None. && $$
National Weather Service Hastings NE
1012 PM CDT Sun Jun 7 2020 ...Short Term Update... .UPDATE... Issued at 1012 PM CDT Sun Jun 7 2020 Will defer to oncoming overnight shift to dig into this much deeper and make necessary forecast adjustments, but general trend from some of the latest 00Z models (especially HRRR/NAM12) suggests that the incoming frontal boundary could be slowing enough to focus the vast majority of any Monday late afternoon- evening severe storm potential almost completely to the northwest of our CWA, with the main focus clearly over the WFO LBF domain. Other models still show some pre-sunset potential in our western- northwest counties, so this is not a "sure thing". However, if this slower trend looks to continue, then our overall severe storm messaging for Monday in our HWO/graphics etc. may need to undergo some somewhat-notable changes. Will be interesting to also see if the upcoming Day 1 SPC outlook perhaps trends northwest a bit from the current Day 2 configuration. UPDATE Issued at 556 PM CDT Sun Jun 7 2020 Within the past hour, have updated our routine forecast products and Hazardous Weather Outlook (HWOGID) mainly to address the following: - Strong south winds: Winds today ended up being a bit stronger than expected (especially from our forecast of 24 hrs ago), with numerous official/unofficial stations reporting peak gusts in the 45-55 MPH range, and even a few sites (including Ord airport) falling BARELY shy of official High Wind Warning criteria with a 57 MPH gust. Although we have opted against a formal/short-fuse High Wind Warning in our western counties given that the likelihood of anything more than a rogue/isolated 58+ MPH gust seems quite low from here on out, the HWO text was beefed up to reflect the potential for "near-severe" gusts up to around 55 MPH. Although it will remain noticeably breezy/windy right on through the night with gusts commonly 30+ MPH even past midnight, the potential for widespread strong gusts of 45+ MPH should drop off near/after sunset. - Patchy blowing dust: Going hand in hand with the strong winds, we have heard of at least patchy blowing dust/reduced visibility today within our coverage area (CWA) this afternoon, especially near open/recently- worked fields. While very localized areas could certainly be experiencing greatly-reduced visibility, we have opted against a formal Blowing Dust Advisory due to the fact that visibility issues/impacts do not seem very widespread. However, have added "patchy blowing dust" to the routine forecast CWA-wide through 10 PM, and also introduced a mention of potential visibility reductions in blowing dust to our HWO. && .SHORT TERM...(This evening through Monday) Issued at 302 PM CDT Sun Jun 7 2020 Main issue in the short term will be timing of possible precip for Monday afternoon/night. Cirrus stuck around a bit longer during the day today and did seem to knock temps down a tad. Some ACCAS showing up on satellite, and I would not be surprised if we got a sprinkle or two from these high based features. Not much consequence from these. Another night of warm air advection, with a breeze, with some decoupling involved. For Monday, the cold front approaches slowly from the northwest, and our temperatures should boost into the 90s once again for highs. Could be some compressional warming just ahead of the front, but some mid-level sky cover could help to tamp temps from full potential. Wide display from models for timing, placement, and amount of precip. The experimental HRRR is clearly the outlier for how slow the cold front/precip makes it to the east, and pretty much holds off on our CWA from getting precip into overnight Monday night. The rest of the models are more liberal with eastward progress, and as I think that the experimental HRRR could be on to something, especially considering Cristobal heading north from the Gulf, I cannot completely buy into it. I did take a bit of a compromise there. .LONG TERM...(Monday night through Sunday) Issued at 302 PM CDT Sun Jun 7 2020 We could get some training of cells develop by Monday night, especially our northern CWA where better support will be. It is actually looking like a better chance of localized flooding may be toward Tuesday in the post-frontal regime with elevated convection. I expect quite a bit of wind with strong cold air advection, socked in with stratus and plenty of rain. Elevated convection could push the already strong wind gusts to close to 50 mph, perhaps. Temps may struggle to hit 70s for much of the CWA. I went closer to CONSMOS wind speeds over the initialized NBM with the anomalously strong cold air advection for this time of year. As far as severe potential for Saturday afternoon/evening. Severe parameters certainly support any convection that develops along and ahead of the front. The limiting factor for us will be timing. By the time much of the convection reaches our CWA, much of the severe potential will likely decrease, turning the main hazard into isolated/localized flooding later into Monday night. By Wednesday we finally dry out behind the front and upper level ridging should warm us up by late in the long term, especially toward the weekend, and perhaps a bit more than our forecast. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Tuesday) Issued at 721 PM CDT Sun Jun 7 2020 General overview: Although there is the slightest chance of thunderstorm activity trying to get underway toward the extreme end of this valid period (around 00Z Tuesday), this is actually a fairly high-confidence forecast regarding expected dry weather/VFR visibility, and medium-high confidence forecast for VFR ceiling. Overall, the greatest aviation issue remains strong southerly winds, both at the surface and slightly above it, with low level wind shear (LLWS) developing again overnight. Read on for more element- specific details... Winds (including LLWS): At the surface, especially these first 6-9 hours will be fairly windy, with southerly sustained speeds commonly 25-30KT/gusts 35-40KT. Although still quite breezy, speeds during the latter half of the period will tone down a bit, with sustained southerly speeds averaging closer to 20KT/gusts mainly under 30KT. As for LLWS tonight, although the actual magnitude of shear will be somewhat modest (around 30KT) due to the continued gusty surface winds, a formal LLWS inclusion is certainly justified given that speeds within roughly the lowest 1,500 ft. will average a solid 50-55KT from the south, especially during the 03-12Z time frame. Ceiling trends: Although have maintained VFR throughout (and with high confidence through at least the first 12 hours), there are hints that a low- end VFR ceiling (perhaps flirting with high-end MVFR briefly) could materialize at times especially Monday afternoon, so this bears watching. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...Pfannkuch SHORT TERM...Heinlein LONG TERM...Heinlein AVIATION...Pfannkuch
Area Forecast Discussion
National Weather Service North Platte NE
623 PM CDT Sun Jun 7 2020 .UPDATE... Issued at 351 PM CDT Sun Jun 7 2020 Wind gusts to around 60 miles per hour have occurred at Imperial, North Platte and Broken Bow. This is about 10 mph faster than the HRRR model predicted this morning. Strong gusts should continue to sunset and a high wind warning is now in effect for parts of southwest and central Nebraska. && .SHORT TERM...(This evening through Monday night) Issued at 327 PM CDT Sun Jun 7 2020 A reasonably strong cap is in place this afternoon across wrn and ncntl Nebraska but a few of the CAMs indicate a brief but intense period of storm development late this afternoon. With the loss of daytime heating this evening, the cap will strengthen and the models show the storms quickly dissipating. SPC asked for a 20z LBF upper air sounding to determine the strength of the cap which would dictate the potential for severe weather. If any of the vaulting towers this afternoon can build down through the cap layer and tap into the boundary layer moisture, 50kt winds at h500mb and MLCAPE between 2500 and 3000J/KG would support supercells. No other convection is expected tonight or Monday morning. An anomalous upper low featuring -30C temperatures at h500mb has moved into the Pacific Northwest. The upper low will move east tonight and drive a Pacific cold front into cntl Nebraska Monday afternoon. The front and the upper low will be the basis for a combined severe weather/flood threat late Monday afternoon through Tuesday morning affecting the eastern Sandhills, southwest and ncntl Nebraska. Precipitable water in the models increases to between 1.5 and 2.0 inches supporting the heavy rain threat which will occur along and north of the front. The models show about a 50 mile wide swath of heavy rain behind the front Monday night with totals around 4 inches. WPC suggested slow moving storms, warm cloud precipitation processes, storm training and back building will contribute to the flood threat Monday night. Along and ahead of the front, SPC suggested a tornado threat late Monday afternoon and Monday evening. Wind damage and large hail would be possible west or behind the front. A flood watch is in place for Custer county Monday night. Recent heavy rainfall in this area has pushed 3-hr flood guidance below 2 inches in many areas. The location of the front, which could be as far east as Norfolk to McCook or as far west as Imperial to O`Neill, will dictate the location of the tornado threats and there is about a 50 or 70 mile spread in the models east and west with the location of the highest rainfall amounts. .LONG TERM...(Tuesday through Sunday) Issued at 327 PM CDT Sun Jun 7 2020 An upper level trof will move across wrn and ncntl Nebraska Tuesday. Moisture wrapped around a closed h700mb low moving through Nebraska is the basis for ocassional showers throughout the day. The h700mb low and the moisture will exit the region Tuesday night. Dry weather is in place Wednesday through Saturday. The models are in reasonably good agreement showing another upper low/trof moving through the wrn U.S. next Sunday. This would be the next chance for thunderstorm development. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 623 PM CDT Sun Jun 7 2020 Wind is the primary aviation weather concern for western and north central Nebraska. Strong southerly winds will continue to gust frequently around 40 kts through sundown, then slowly decrease overnight to where most gusts should subside by 08/12z. However, low level wind shear conditions arise with a 55+ kt southerly jet at 2kft. A cool front begins to work through the region Monday morning, resulting in a wind shift to northwesterly and some gusts above 20 kts again during the afternoon. Another concern, primarily this evening, is scattered thunderstorms in the panhandle and western Sandhills. Brief drops in cigs/visby, along with erratic wind gusts, are possible at KGRN, KVTN, KTIF. && .LBF WATCHES/WARNINGS/ADVISORIES... High Wind Warning until 9 PM CDT /8 PM MDT/ this evening for NEZ038-058-059-069>071. Flood Watch from Monday evening through Tuesday morning for NEZ038. && $$ UPDATE...CDC SHORT TERM...CDC LONG TERM...CDC AVIATION...Snively
Area Forecast Discussion...UPDATED
National Weather Service Miami FL
838 PM EDT Sun Jun 7 2020 .Update... High pressure continues to build into the Florida Peninsula from the Atlantic waters this evening, as Tropical Storm Cristobal continues to move northward through Louisiana. The high will continue to build into the Florida Peninsula tonight bringing in drier air to the region. Therefore, POPs have been removed from most of South Florida for tonight, except for the east coast areas where a few showers could work into this region from the Atlantic waters late tonight on the easterly wind flow. The threat of rip currents have also decreased along the east coast beaches of South Florida this evening, as the wind speeds have fallen below 15 mph. The wind speeds will continue to slowly decrease through the night hours tonight. Therefore, the High Risk of Rip Currents along the east coast beaches of South Florida has been allowed to expire. However, the threat of rip currents will continue along with the coastal flood statement for the west coast beaches of South Florida tonight, due to the westerly swells from Tropical Storm Cristobal. Rest of the forecast looks good at this time and no other changes are planned. && .AVIATION... The winds will remain easterly around 5 to 10 mph tonight over all of the TAF sites with mostly dry conditions. There could be a shower or two over the east coast taf sites late tonight into early Monday morning, but the coverage will be few and far between to put it in the east coast TAF sites at this time. The ceiling and vis will also remain in VFR conditions over all of the TAF sites. && .Prev Discussion... /issued 327 PM EDT Sun Jun 7 2020/ Short Term (Rest of Today-Monday)... Previous Mesoscale Discussion for highly conditional convective potential for this afternoon: There is a conditional risk of a few strong to locally severe thunderstorms developing across portions of South Florida this afternoon into the early evening hours. At this time, it appears that afternoon convection could initiate somewhere across the southern Everglades of South Florida by the early to mid afternoon hours where pockets of cloud clear/thinning are evident in GOES-16 visible imagery loops and horizontal convective rolls (HCRs) are developing. If convection can initiate and withstand the negative effects of enhanced dry-air entrainment in association with an elevated mixed layer (EML) plume across the eastern portions of South Florida, the storms will likely advect northward or northeastward with the mean steering flow. This storm motion could increase residence time of convection within strong surface-based buoyancy. At this time, areas from the interior/Lake Okeechobee region towards Palm Beach County may be at the greatest risk of seeing a few strong to locally severe storms. All convective hazards will be on the table with the more robust convection that may develop today, to include strong to isolated damaging wind gusts, funnel clouds/brief tornados, small hail, and lightning. Once again, these convective hazards are referring to a reasonable-worst-case scenario and are conditional upon the magnitude of mesoscale convergence which will be required to trigger deep moist convection. In the lower-levels, South Florida is under the influence of the western periphery of Atlantic subtropical high pressure and the outer periphery of Tropical Storm Cristobal. This is allowing for enhanced southerly surface flow and rich boundary-layer moisture advection (highlighted by dewpoints in the upper 70s across South Florida). In addition to strengthening surface-based buoyancy associated with the rich boundary-layer moisture, enhanced southerly low- level flow is also acting to locally elongate low-level hodographs, allowing for modest stream-wise vorticity across South Florida. In the mid-levels, dry air has worked into the region (potentially associated with the aforementioned EML. The EML may have advected across the eastern portions of South Florida throughout the day yesterday and has acted to locally steepen maximum mid-level lapse rates to an impressive 7.7 C/km (per todays 12Z MFL RAOB). While the dry air aloft will enhance the negative effects of dry-air- entrainment on convective updrafts, the steep mid-level lapse rates will allow for enhanced upward parcel accelerations in updrafts, acting to offset the negative effects of the dry-layer aloft and precipitation loading. The EML may be associated with a subtle Saharan Air Layer (SAL) that was evident in GOES-16 True Color imagery to the SE of South Florida. These mid-level lapse rates may begin to advect out of the region through the day today, which is being depicted in current RAP mesoscale analysis. This would greatly reduce the risk of stronger wind gusts and hail development today. In the upper-levels, a closed 300-200mb high pressure is situated over Cuba. The is allowing for enhanced southwesterly to westerly flow aloft, and helping to provide weak, albeit some synoptic ascent in the form of differential divergence across South Florida. Deep-layer shear is currently on the order of 25 to 30 knots, which will help to organize convection and separate updrafts and downdrafts. As previously mentioned, low-level shear is also enhanced today across South Florida, highlighted by 0-3km SRH of 120 m2/s2 from todays 12Z MFL RAOB. If 0-3 km lapse rates are able to locally steepen in association with pockets of surface heating today and mesoscale convergence can become enhanced, this could increase the realization of stronger convection today. There is plenty of uncertainty regarding the initiation and maintenance of deep moist convection this afternoon. Any convection that does develop should diminsh after sunset with a generally dry overnight period. A warm and muggy night across the region with cloud cover continuing to allow temps not to cool very much overnight. Monday: As we move into Monday, mid-upper level ridging with a southeasterly wind flow. However, overall flow will be lighter as the gradient decreases with Cristobal weakening after landfall and continuing to move northward. Therefore, sea breezes will be the main forcing for convection. There is a moisture tail from TS Cristobal that allows the mid-levels to moisten compared to todays drier air and the presence of EML/SAL dissipated. This combination will allow allow better coverage of storms. Temperatures will remain in the upper 80s to low 90s, with dew points in the upper 70s, it will feel like near 100 degrees with the muggy humid weather continuing. Long Term (Tuesday through end of the week)... The aforementioned mid-upper level ridging and building sfc high will allow flow to become more easterly as we move towards the middle part of the week. Another surge of tropical moisture moves into the region on Wednesday with precipitable water levels around 2 inches. Although, still a typical summertime sea breeze convective pattern better overall coverage is expected on Wednesday, with highest coverage over the Lake Okeechobee and interior regions given the flow regime. As we move towards the end of the work week we get some relief from with some drier air moving into the mid-upper levels. A upper level trough almost TUTT like moves in from the western Atlantic helping to dry out the mid-upper levels as can be seen on model soundings down to 1.5 inches or less. This will help lower overall coverage and rain chances across South Florida as we end the work week. High temperatures throughout the long term will generally range from the mid to upper 80s, with low 90s across SW Florida. High humidity will keep max heat indices in the mid to upper 90s to low-mid 100s. Marine... Scattered showers and storms across the area the next few days. Southerly winds will gradually become easterly as high pressure builds across the region. Gulf marine conditions will gradually improve as swell, seas and winds begin to diminish as TS Cristobal makes landfall and moves north. Aviation (18Z TAFs)... Primarily VFR conditions expected through the TAF period. Lingering MVFR cigs from earlier have mostly lifted. Convective coverage remains limited so far this afternoon, though isolated development remains possible across interior South Florida this afternoon. Expect brief bouts of MVFR to IFR cigs/vis in and around any of the stronger storms that may develop today. Beach Forecast... There is a high risk of rip currents at all South Florida beaches through this evening. A high risk of rip currents will remain at the Gulf coast beaches through at least Monday, as swell and surf from TS Cristobal gradually diminishes. Coastal Flooding: With the full moon, the concern of minor coastal flooding continues through the weekend. For the Gulf coast, swell from Cristobal will combine with the higher-than-normal high tides to create the potential for minor coastal flooding. && .Preliminary Point Temps/PoPs... West Palm Beach 77 89 76 88 / 10 20 10 30 Fort Lauderdale 80 87 78 87 / 10 20 10 30 Miami 79 89 77 88 / 10 20 10 30 Naples 78 89 76 89 / 10 20 10 30 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...High Rip Current Risk through Monday evening for FLZ069. AM...None. GM...Small Craft Advisory until 10 AM EDT Monday for GMZ656-657-676. && Update...54/BNB Marine...33/Kelly Aviation...54/BNB Beach Forecast...54/BNB Short Term...33/Kelly Long Term...33/Kelly
Area Forecast Discussion
National Weather Service Blacksburg VA
1046 PM EDT Sun Jun 7 2020 .SYNOPSIS... High pressure keeps the area drier with lower humidity into Monday. As the flow turns around Tuesday look for increasing moisture. A front arrives midweek with our next threat of showers and storms. && .NEAR TERM /THROUGH MONDAY/... As of 1045 PM EDT Sunday... Temperatures still running several degrees cooler than anticipated, so lowered them again. The overnight lows still look good, it was mainly the hourly T grids that were just not trending down quick enough in this currently dry surface air mass. In the southwest part of the CWA, small light rain showers have been popping up in the Watauga/Wilkes county area. This has been consistently shown by the HRRR and the NAMNest simulated radar progs and also coincides with an area of easterly wind and surface moisture convergence. Dewpoints transition from the lower 60s across northern Watauga and Wilkes to the lower 70s near the southern border of these counties. These same models show this precipitation expanding northeastward along the Blue Ridge overnight, but confidence in this occurring is low at this point, but will need to be watched. Bottomline, clouds were increased in northwest NC through the night/morning hours and also pops were brought up to slight change for -SHRA from TNB to MWK and UKF over the next few hours. As of 800 PM EDT Sunday... Only some minor tweaks to the T, Td, Pop, Sky, Wx, and Wind grids this hour. Temps were running just a bit warmer than anticipated, but not make any changes to the overnight lows at this time, only the readings over the next 3-4 hours. Pops seemed a bit high across the southwest part of the CWA leaning toward the NAM Nest, which does not seem to be verifying well per latest radar and satellite. There is a significant dewpoint discontinuity near the I-40 corridor, just south of our CWA border, where 70+ dewpoints exist, while dewpoints in our NC counties are mostly in the lower 60s. The drier air to the north should continue to spread south into central NC overnight. On the contrary, easterly flow will set up as high pressure moves off the New England coast. This could cause an increase in clouds and possibly sprinkles or light showers in the NW NC mountains early Monday, but leaning against that idea for now. As of 133 PM EDT Sunday... Keeping it dry through tonight, though some higher res models are trying to develops showers along our southern forecast area this afternoon into tonight along frontal boundary and lingering higher pwats. Sprinkles/isolated showers not out of the question mainly south of U.S. 421 from Watauga to Yadkin county. Otherwise, expect a drier airmass into Monday though still warm. An inverted trough/warm front tries to make it to the mountains of NC/VA Monday. Allowed for isolated showers/storms across the High Country into southern Wilkes, but at the same time we will be under the upper ridge, and forecast soundings suggest capping in place until dusk, so confidence is low on any development. Should be close to normal for lows tonight, ranging from around 60 in the piedmont, to lower to mid 50s in the mountains, with even some 40s in the far western valleys. Monday temperatures still warm with highs in the 80s. Humidity tries to creep up in the afternoon, especially south of the the VA/NC border. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/... As of 230 PM EDT Sunday... Upper ridge elongated from eastern Ohio Valley to the southeast will break down through Wednesday as trough digs across the center of the country, while remnants of Cristobal head north west of the MS River. Moisture on the backside of the surface high with a warm front moving north across the TN Valley and southern Appalachians will increase this period, so after a brief respite from the muggies, we return to humid airmass by Tuesday. Showers and storms will be mainly confined to the southern Appalachains Monday night, then should see an uptick in coverage Tuesday mainly from southern WV to the NC mountain/foothills ahead of the warm front. We will be fully in the warm sector Tuesday night/Wednesday ahead of the cold front and with flow turning more southwest will see better threat of showers and storms by Wednesday afternoon at least west of the foothills into the mountains, then the front edges east to the piedmont Wed night, though difference in model speeds suggest keeping at least a good chance of showers/storms around into the evening/early overnight especially east of the mountains. Forecast confidence is high early on, then below average for pops Wednesday-Wed night, as far as timing. && .LONG TERM /THURSDAY THROUGH SUNDAY/... As of 1120 AM EDT Sunday... Broad upper trough will be situated from southern Canada south into the TN valley. Models in general agreement that Wednesdays front should be east of us Thursday, but upper ridge and weaker flow off the coast may slow it down enough to keep shower chances in for at least the piedmont. Overall. mainly a trough along/west of us in the upper levels, into Friday, but differences in models show up late Friday with the GFS closing off a low over Michigan, while the ECM keeps the trough progressive. Hence the GFS showing another front with shower threat Friday afternoon into Saturday as the closed low sticks around over the Ohio Valley. The ensemble mean does not show this, and is more line with the operational Euro. As such will keep it dry Friday, but even the shortwave per Euro Saturday may be enough to spark showers in the heating of the day so leaned toward a slight/low chance pops. By Sunday, both the GFS and Euro have the upper trough axis situated over our area, with the GFS still showing the closed low over the mid-Atlantic while the Euro is further north over southwest Quebec. With trough axis overhead, shower chances are possible with better chance with the frontal boundary east of our area. Temperatures this period will be closer to normal and humidity levels will also be tolerable most of the time, especially in the mountains. Given the discrepancies in the models especially Friday-Saturday, forecast confidence is average on precip chances. && .AVIATION /03Z MONDAY THROUGH FRIDAY/... As of 800 PM EDT Sunday... VFR conditions are expected to prevail through much of the TAF valid period. The exceptions will be the limited potential for MVFR in fog at LWB early Monday and MVFR clouds morning and again late afternoon around TNB and the far southwest part of the CWA. Otherwise, look for mostly clear skies across the CWA except the far southwest where developing easterly/northeasterly flow could result in increasing MVFR clouds late tonight and Monday, say from TNB to MJK. Otherwise, a dry air mass should keep skies clear to partly cloudy (few to sct cu) through the TAF valid period. Winds will be NNW west of the Blue Ridge to NE east of the Blue Ridge overnight at speeds of 4-8 mph, becoming NE-SE Monday morning at speeds of 5-10 mph, with low end gusts possible mainly east of the Blue Ridge by late morning. /Confidence Levels in Forecast Parameters/ Ceilings - Moderate to High, Visibility - High, Winds - Moderate to High. /Thunderstorm Threat TAF Valid Period/ None. Extended Aviation Discussion... MVFR conditions are expected to develop across the NW NC mountains Monday evening and into far southwest VA around MJK and toward MWK/HLX. As moist easterly flow continues and the trail of moisture associated with the remnants of T.S. Cristobal track through the Midwest, look for increasing amounts of MVFR ceilings spreading north and northeast through the CWA Tue-Wed. Scattered showers/thunderstorms return to the west/mountains Tuesday with showers/thunderstorms likely on Wednesday as a front moves in from the west combined with moisture from Cristobal. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...WP NEAR TERM...RAB/WP SHORT TERM...WP LONG TERM...WP AVIATION...RAB/WP