Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/10/17

Area Forecast Discussion
National Weather Service Dodge City KS
607 PM CDT Sun Jul 9 2017 ...UPDATE TO AVIATION... .SHORT TERM...(This evening through Monday) Issued at 206 PM CDT Sun Jul 9 2017 Broad surface high pressure both at the surface and aloft will drive the sensible weather this weekend. The short term updates this morning mainly keeping pace with the temperature curve of the HRRR model, being slightly warmer through the I-70 corridor, not as hot near EHA/LBL. Temperatures were already into the 90s before 18Z across the west central Kansas counties. Will continue the HRRR`s temperature trend heading through the evening hours, however it is too quick to lower dew points. No convective concerns for at least the next 48 hours with such warm temperatures aloft and generally subsident pattern. Models have even warmer temperatures heading into Monday and the entire area is likely to reach 100 degrees or warmer Monday afternoon. .LONG TERM...(Monday night through Sunday) Issued at 206 PM CDT Sun Jul 9 2017 The hot and dry pattern looks to continue through the entire normal work week. The GFS shows a surface convergence zone developing across west central/nw Kansas by late Tuesday, but again, the mid level temperatures look to warm for any kind of organized development for the DDC area. Temperatures making it to the century mark are likely through the middle part of the week. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 607 PM CDT Sun Jul 9 2017 VFR conditions will prevail at all TAF sites through early Monday afternoon. South winds 10 to 20kt will persist across southwest and central Kansas through Monday afternoon as a lee side trough of low pressure remains anchored across eastern Colorado. && .PRELIMINARY POINT TEMPS/POPS... DDC 71 100 72 101 / 0 0 0 0 GCK 68 100 70 103 / 0 0 0 10 EHA 70 99 69 99 / 0 0 0 0 LBL 71 101 70 101 / 0 0 0 0 HYS 74 103 72 102 / 0 0 0 0 P28 72 99 73 100 / 0 0 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Russell LONG TERM...Russell AVIATION...JJohnson
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
855 PM CDT Sun Jul 9 2017 .UPDATE... /ADDED ISOLATED EVENING POPS NW/ A pair of outflow boundaries careening south toward South Central TX have been generating a few showers and storms in their wakes over West Central and East Central TX. They are moving into a more stable air mass but will also bring a boost in low level dew points as seen at the Brenham AWOS and in HRRR forecasts. Not much rain is expected with the short-lived post-outflow boundary activity, and will follow the hrrr/rap suggestion that all the showers should dissipate by around 04z. Will update the grids to extend chances by another hour over the east and add a sliver of rain chances for a couple hours over the Southern Edwards Plateau. The rest of the forecast remains on track. && .PREV DISCUSSION... /ISSUED 645 PM CDT Sun Jul 9 2017/ AVIATION.../00Z TAF CYCLE/ Mostly dissipating SHRA and TSRA is ongoing just north of KAUS as of 2345Z. However, there is a low-level outflow boundary slowly shifting south that will likely cause a brief north wind shift at 5 to 10 knots at KAUS from 00-01/02Z as it did for KEDC. The remaining SHRA will dissipate through the next hour across south-central Texas. Another line of TSRA exists near San Angelo but that should not make it to KDRT and dissipate across the Edwards Plateau through the evening hours. VFR conditions are expected through the period with predominantly south winds near 10-14 knots. A few gusts to near 20 knots will be likely for KDRT Monday afternoon. PREV DISCUSSION... /ISSUED 307 PM CDT Sun Jul 9 2017/ SHORT TERM (Tonight through Monday Night)... IR and visible satellite images are revealing storm intensity on the rise as cloud top temperatures reach the lower -60C to lower -70C. This activity will continue this afternoon and early evening across central Texas and part of the Hill Country as an upper level shear axis moves to the south into the Hill Country and an outflow boundary from yesterday`s convection sits between the Hill Country and the escarpment. Any strong storm that does manage to develop has the potential for small hail, frequent lightning strikes and localized heavy rains. Rainfall amounts will generally range from few hundredths to one quarter inch with isolated spots getting one to two inches (if storms stall over same area through the period). Once the daytime heating comes to an end, storms are expected to diminish and come to an end between 8 or 9 pm this evening. The rest of the night into Monday morning is expected to remain dry. Overnight lows will range from the lower 70s across the Hill Country to the mid 70s elsewhere. For Monday, expect mostly sunny skies over most areas across South Central Texas with the exception of the far eastern counties. Partly to mostly cloudy skies are expected across the eastern counties mainly in the afternoon. There is a slight chance for rain as the sea breeze moves into the coastal Plains area. Overall daytime temperatures are expected to reach the mid to upper 90s. LONG TERM (Tuesday through Sunday)... A relative dry weather forecast period is anticipated for the first part of the week as the sub-tropical upper level ridge takes control over the local weather. The upper level ridge is forecast to weaken as an upper level inverted trough moves into our area from the east, resulting in an increase of moisture and rain chances for Thursday and Friday. Medium-range models guidance at the moment have different solutions for the upcoming weekend and decided to go with lower end PoPs until they get a better agreeable signal on the extended part of the forecast. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 75 97 76 97 76 / 20 20 - 10 - Austin Bergstrom Intl Airport 74 97 75 96 75 / 20 20 - 10 - New Braunfels Muni Airport 73 97 73 96 74 / 10 - 10 10 - Burnet Muni Airport 73 96 73 95 73 / 20 20 - 10 10 Del Rio Intl Airport 74 99 75 99 76 / 0 0 0 0 10 Georgetown Muni Airport 74 96 75 95 75 / 20 20 20 20 10 Hondo Muni Airport 72 99 73 99 74 / 0 0 0 - - San Marcos Muni Airport 74 97 74 96 75 / 20 10 - 10 - La Grange - Fayette Regional 75 96 76 95 76 / 20 20 10 20 10 San Antonio Intl Airport 75 98 75 97 76 / - - - 10 - Stinson Muni Airport 74 99 74 97 75 / - - 0 10 - && .EWX WATCHES/WARNINGS/ADVISORIES... None. && $$ Mesoscale/Aviation...Allen Synoptic/Grids...Oaks Public Service/Data Collection...33
Area Forecast Discussion
National Weather Service Hastings NE
734 PM CDT Sun Jul 9 2017 .UPDATE... Issued at 729 PM CDT Sun Jul 9 2017 Updated the forecast this evening to increase the chance of thunderstorms significantly in our northern CWA to around 50 percent near Ord, citing the storms that have held together to the north and heading south. There seems to be a decent cold pool helping to propagate these storms south, and along with the developing low- level jet tonight, this could help maintain storms longer than previously thought, and there is an outside chance we could still have some remnants of the storm a bit past midnight. There could be an isolated severe storm in our north, but support for this wanes after sunset. && .SHORT TERM...(This evening through Monday) Issued at 309 PM CDT Sun Jul 9 2017 Firstly, scattered thunderstorms across the northern Sandhills may approach the area after 0Z. Models have mostly killed off this activity before it makes it here, but the last few ones of the HRRR and HRRRX bring it into Valley and Greeley county areas. Therefore, I included a slight chance in these areas. Tonight into tomorrow morning, a cold front reinforced by outflow from the aforementioned storms will move southward across the area for tomorrow. Tomorrow afternoon, a few models, namely the NAMnest and some of the NCAR WRF ensemble members, are developing convection along the I-80 corridor in response to this front. On the other hand the NAM/GFS/ECMWF don`t output any QPF, and soundings look pretty capped. If something does develop, it could be marginally severe thanks to 1500-2000J of CAPE and ~30 kts of 0-6km bulk shear. All that being said, I wouldn`t be surprised if something isolated develops, but the areal coverage and potential are just too low to include at this point. The other point of interest for tomorrow is the heat. Model guidance has lowered temperatures noticably for tomorrow as the front looks to push a little farther south than previously expected. There will probably be a pretty large temperature spread across our CWA, with highs struggling to reach the low 90s near Ord, and blasting into the low 100s in Kansas. .LONG TERM...(Monday night through Sunday) Issued at 309 PM CDT Sun Jul 9 2017 Precipitation chances return to northern parts of the forecast area for Monday night as an upper level wave through the area. The timing of this feature would have develop in western Nebraska during the late afternoon and track into central and north-central Nebraska overnight. In the presence of an 850mb low-level jet, there will be enough instability that a marginal severe threat exists with this activity as well. On Tuesday, a tightening pressure gradient will make for breezier conditions across much of the forecast area. This will help make the heat feel a bit more bearable. This is a good thing, as highs are still expected to be in the upper 90s to low 100s. Tuesday night will bring most of the area a better chance for rain and thunderstorms as we will have decent low and mid-level convergence along a stalled front aided by a strong low-level jet. Thunderstorm chances continue through Wednesday as the aforementioned front sags southward. This will also keep temperatures a few degrees cooler on Wednesday. Thursday through Saturday, the weather pattern looks to remain pretty stagnant in zonal flow, with daily chances for thunderstorms and highs in the low to mid 90s. The GFS shows us moving back into more northwesterly flow Saturday into Sunday, possibly bringing us a bit cooler air late next weekend into the following week. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Monday) Issued at 657 PM CDT Sun Jul 9 2017 Biggest issue will be low-level wind shear when the low-level jet develops and increases overnight. Thunderstorm activity to the north should die out before it would arrive, as much of it is diurnally driven. && .GID WATCHES/WARNINGS/ADVISORIES... NE...None. KS...None. && $$ UPDATE...Heinlein SHORT TERM...Mangels LONG TERM...Mangels AVIATION...Heinlein
Area Forecast Discussion
National Weather Service Wilmington NC
958 PM EDT Sun Jul 9 2017 .SYNOPSIS... A weak cold front will stall across the area through Monday, enhancing the risk for thunderstorms and excessive rainfall. The front will slowly dissipate Tuesday as the Bermuda ridge builds back across the Carolinas. The Bermuda ridge and Piedmont trough will produce typical summertime heat and humidity and afternoon and evening thunderstorms Wednesday through Friday. Heat index values mid to late week will approach 105 degrees. A cold front will approach Saturday with cooler temperatures and better rain chances. && .NEAR TERM /THROUGH MONDAY/... As of 945 PM Sunday...Over the past two hours the heaviest rainfall has shifted south to a line from Conway into northern Williamsburg County. This is quite fortunate since radar storm- total rainfall amounts were exceeding 5 inches in spots. The mesonet station in Green Sea, SC (Northern Horry County) has received 4.18 inches today which is roughly 10-20 percent higher than either dual-pol or legacy radar products indicated. A recent chat with the WPC Metwatch forecaster was fruitful and revealed some additional reasoning about ongoing rainfall this evening. Most notably, a right-entrance region of a jet streak located off the Mid-Atlantic coast sits across the eastern Carolinas. The upper divergence within this "acceleration lane" aloft is helping support upward vertical motion even as ongoing convective processes stabilize the boundary layer. Outflow boundaries have continued to focus new convection and are also contributing to aberrant cell motion which has had a considerable backbuilding/upstream component through the evening. On this latest update, I have focused the remaining heavy rain threat across Conway, Brittons Neck, and Lake City southward to the Santee River for the next 3 hours. New convection developing back across the Sandhills is moving little, and may feed eastward toward Florence and Dillon after midnight. The RAP model is outperforming the HRRR significantly this evening. Discussion from 800 PM follows... Another update to the forecast to increase rainfall forecasts to an additional 3+ inches in the area from Tabor City southward across Conway and into northern portions of Georgetown and Williamsburg Counties. I contemplated a short- term Flash Flood Watch, but this event could be over in the next 2-3 hours and will be handled by warnings at this point. Boundary collisions and back-building cell motion continues to dump rain across the same areas, leading to these excessive rainfall totals. Latest dual-pol and legacy radar estimates are between 4-5 inches from the towns of Tabor City, NC to Green Sea, SC. && .SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/... As of 300 PM Sunday...The mid level pattern will become poorly defined across the area through the period, which is quite typical this time of year. Any lingering fronts or boundaries will have all but washed out leaving the standard local or regional features to work with what will still be a very moist airmass as precipitable water values hover near an inch. Guidance does show a decent chance of overnight convection late Monday into early Tuesday with a shortwave moving across from the west. For the day Tuesday the sea breeze and Piedmont trough will be the primary triggers. It appears as of now overnight Tuesday into early Wednesday may see a quiet overnight period, the first in some time as the weak flow is void of any shortwaves. No changes to the temperature forecast which should remain just a notch or two above climatology. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... As of 300 PM Sunday...First half of the extended offers a return to heat and humidity as mid-level ridge expands across the Southeast. The mid-level ridge expands from the east and extends into the Carolinas, beneath which a surface Bermuda-type high strengthens. This will bring hot temperatures back into the region, along with increasing humidity on return flow. Highs on Wednesday will rise into the low 90s most locations away from the immediate beaches, with heat index values climbing over 100. Thu-Fri will be just as warm, and feel even hotter, with heat index values climbing to near 105 both aftns. Scattered diurnal showers and tstms will be possible each aftn as well, but subsidence beneath the ridge and lack of significant mid- level forcing will keep coverage isolated at best. As we head into the wknd, the ridge will amplify across the mountain west driving a longwave trough into the eastern CONUS. This will suppress the ridge locally into the GOM, and cause increasing shower and tstm chances as well as bring cooler, more seasonable, temps to the Carolinas. A cold front will likely sink south into the region at the leading edge of the trough, and then stall across the area. This will create much more unsettled weather to the region with good shower/tstm chances through the wknd. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... As of 00Z...Very heavy thunderstorm activity between Florence, SC and Wilmington, NC is backbuilding southwestward very slowly and poses a threat to the two Myrtle Beach airports (MYR and CRE) through the evening hours. Our latest forecast includes a tempo group of thunderstorms and MVFR conditions developing between 01-05Z at MYR and CRE. If a thunderstorm cell develops directly over one of these airports, expect IFR conditions to develop with visibility measured at less than 1 mile earlier in Whiteville, NC. Less certain is the potential for storms in the vicinity of the ILM airport this evening. Radar trends indicate the heaviest storms may remain off to the southwest. For the FLO airport we`re watching storms advancing northward from the Manning, SC vicinity that could pose a threat by 03Z. Beyond midnight local time, convective activity should concentrate south of Florence and west of the Myrtle Beach airports, potentially expanding again after 09Z as moisture offshore begins to surge inland. Extended Outlook...MVFR/IFR conditions are possible from thunderstorms as a stalled front dissipates across the area Monday night into Tuesday. && .MARINE... NEAR TERM /THROUGH MONDAY/... As of 945 PM Sunday...The coastal waters has thus far escaped much of the rough weather inland this evening. This may be changing as an outflow boundary that just pushed off the coast around Myrtle Beach may spark the development of new storms along coast from Oak Island down across the Grand Strand in the next hour. Outside of thunderstorms the synoptic winds remain from the southwest around 10 knots, with seas 2-3 feet, with little change anticipated overnight. Discussion from 800 PM follows... No significant changes are needed to the forecast. Today`s seabreeze was rather anemic given the weak temperature contrasts across the beaches, and winds are generally less than 15 knots. Wind speeds around 10 knots from the southwest are expected overnight, with variability near thunderstorms may which become more common near the beaches of Myrtle Beach and Cape Fear later this evening. Discussion from 300 PM follows... A weak cold front will slowly dissolve upstream ahead of building western Atlantic ridge. Sustained wind speeds into tonight and though Mon will be 10 to 15 kt. The direction will be S into early this eve, becoming SSW/SW tonight and Mon. Seas will remain about 3 ft throughout. Showers and thunderstorms with heavy rain will become numerous to widespread, especially late tonight and on Mon. SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/... As of 300 PM Sunday...Bermuda High pressure will continue to be the dominant feature across the coastal waters through the short term period. Expect winds from the south/southwest of 10-15 knots through the period. There may be a slight enhancement to just above 15 knots overnight Monday into early Tuesday with the low level jet. Significant seas will be 2-4 feet. LONG TERM /WEDNESDAY THROUGH FRIDAY/... As of 300 PM Sunday...High pressure centered well offshore will expand and ridge back into the Carolinas through the end of the week. This persists SW winds across the waters, with only slow increase in speeds from around 10 kts Wed/Thu to 10-15 kts Friday as the gradient pinches ahead of an approaching cold front from the NW. This front will remain well NW of the waters through the period, but these stronger winds late will create the highest seas of the week on Friday. 3-4 ft seas will be common on Friday with a SW wind wave amplifying in the spectrum, after several days of 2-3 ft thanks to a low amplitude SE swell and SW wind wave earlier int he week. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...JDW NEAR TERM...TRA SHORT TERM...SHK LONG TERM...JDW AVIATION...TRA MARINE...
Area Forecast Discussion
National Weather Service Lincoln IL
830 PM CDT Sun Jul 9 2017 .UPDATE... Issued at 825 PM CDT Sun Jul 9 2017 Warm front slowly lifting northeast across the forecast area this evening coupled with a weak upper level disturbance tracking across eastern Illinois produced some widely scattered thunderstorms. Surface Capes late this afternoon were ranging from 2500-3000 J/Kg and right along and to the east of the warm frontal boundary we have been watching some rather high 0-3km Helicity values along and to the east of I-57. We received a public report of a funnel cloud about 2 miles east of Tilton with a small storm that exhibited low and mid level rotation for several volume scans before it gradually weakened as it tracked into far western Indiana just after 7 pm. The scattered cells to our west were dissipating early this evening and most short term models continue with that idea thru the evening. Severe storms have finally developed over parts of central Minnesota early this evening and it is from that area that we will watch to see how the storms track into the early morning hours. The last few runs of the HRRR model continued to show the strong storms tracking southeast into northeast Iowa and then into northwest Illinois after Midnight, and finally into at least the northern half of the forecast area after 2 or 3 am. The last few model runs have trended slower with the arrival time in our area. Highest POPs will remain across the north late tonight and into Monday morning, and then with numerous mesoscale boundaries left over from the late night convection for storms to refire on again Monday afternoon during peak heating. No major changes made to the grids early this evening, as a result, no ZFP update will be needed at this time. && .SHORT TERM...(This evening through Monday) ISSUED AT 244 PM CDT Sun Jul 9 2017 Main concern for this period will be with convective trends. Convective complex is expected to develop across central Minnesota and dive southeast this evening with an enhanced threat of damaging winds. While the apex of this expected bow echo is projected by most of the high-resolution models to stay to our north, they do suggest at least part of the line moving into northern parts of the CWA overnight. The ARW indicates this could occur as early as 2-3 am, while the HRRR focuses more on the 4-5 am time frame. Any lingering rain from this system should be out of the area by mid to late morning. The atmosphere is expected to have plenty of time to destabilize in the wake of this first cluster of storms, with both the NAM and GFS projecting surface based CAPE`s to rise to over 4,000 J/kg during the afternoon across the northwest half of the forecast area. The incoming cold front and/or the residual outflow boundary from the earlier storms will provide the focus for another line of storms to form across the northern third of the state around mid afternoon, dropping southward. Latest SPC Day2 outlook introduced a slight risk of severe storms for this scenario. .LONG TERM...(Monday night through Sunday) ISSUED AT 244 PM CDT Sun Jul 9 2017 Ongoing concern much of the week will be with the persistent heat, as the warm air mass that has been prevalent over the west half of the U.S. spreads eastward. Current indications are that traditional heat advisory levels (heat index at least 105 degrees) would not necessarily be met, but an advisory could be warranted due to the duration of 100+ degree heat indices. Right now, it appears Thursday provides enough of a question mark due to convective issues to hold off on any advisories, but will continue to hit the issue hard in the Hazardous Weather Outlook. In terms of the convection, a zonal flow will be setting up early this week, with periodic waves riding along it. As such, it will be tough to get any extended rain-free periods, although the rain should not be continuous. Early on, much of the northern and central CWA will see the main focus for this, as any surface boundaries would not have much of a reason to move out of the area. However, by about Thursday, a rebuilding of the western ridge will get the Great Lakes back into more of a northwest flow, which will help Thursday`s front push further south toward the Ohio Valley. As such, PoP trends significantly drop off late in the week. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 545 PM CDT Sun Jul 9 2017 VFR conditions are expected through the forecast period. Main forecast concern will be timing of a complex of storms that will be forming in central Mn in the few hours and then shifting southeast later this evening. Latest high resolution forecast models suggest the timing in our northern TAF sites, including CMI, would be from 08z-10z. The potential with these storms late tonight/Monday morning will be strong shifting winds into the north and northwest along with lower cigs/vsbys in brief heavy rain. At this point, confidence still not that great with respect to the storms reaching SPI and DEC by dawn Monday, so will lean on keeping any mention out at this time. Convection and any restrictions to vsbys and cigs, should move out of our area by late morning on Monday with the potential for storms to redevelop after 20z across the forecast area. Surface winds will be south to southwest tonight at around 10 kts but if storms affect a TAF site, winds will be variable in direction, mainly from the north to northwest, with gusts up to 40kts possible along the surging outflow boundary, especially at PIA and BMI. Away from storms on Monday, surface winds will be southwest at 12 to 17 kts in the afternoon with a few gusts up to 23 kts at times. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Smith SHORT TERM...Geelhart LONG TERM...Geelhart AVIATION...Smith
National Weather Service Jackson KY
745 PM EDT Sun Jul 9 2017 .UPDATE... Issued at 720 PM EDT SUN JUL 9 2017 Did an update to the grids through the rest of the evening. Mainly adjusted the Sky and added the latest T/Td obs and trends. These have been sent to the NDFD and web servers. && .SHORT TERM...(This evening through Monday night) Issued at 440 PM EDT SUN JUL 9 2017 20z sfc analysis shows high pressure in control of the weather across eastern Kentucky making for plenty of sunshine, comfortable humidity levels, and pleasant afternoon temperatures in the upper 70s and lower 80s. Fair weather cu is found locally through far eastern parts of the area with other high clouds impacting the region as they work southeast through the Ohio Valley from northern Illinois and Indiana. Meanwhile, winds are light and variable with dewpoints running in the mid to upper 50s. The models are in good agreement aloft through the short term portion of the forecast. They all depict several notable shortwaves rotating through the deep eastern trough over the region. A weak one is exiting to the east of Kentucky this afternoon with a more substantial one passing to the north by 18z Monday. Another one will follow on its heels approaching the area by 12z Tuesday. Despite the small scale nature of these features the models have them similarly represented lending some confidence to their individual wx details. Given the model agreement will favor a general blend with significant deference given to the higher resolution HRRR and NAM12 specifics. Sensible weather will feature a quiet night with mostly clear skies through the bulk of it. This will lead to patchy valley fog forming again late tonight along with another decent ridge to valley temperature split. Owing to dewpoints falling into the upper 50s most places this afternoon have allowed the temps to fall a bit more than CONSShort and MOS. Towards dawn we will have to watch for potential outflow driven convection impacting our northern zones per the latest HRRR and NAM12. The threat will linger through the day as boundaries will likely settle south into our area generally north of the the Mountain Parkway. Moisture and warmth will build up during the day, as well, fueling the storm potential for those northern locations. For Monday night, we still could see a mild ridge to valley difference as the diurnal clouds diminish but milder conditions and higher dewpoints will limit the temperature drop off. There will be another threat of showers or a storm late at night from the northwest, but likely not until after dawn - again just affecting our northern counties. Look for some patchy fog in the valleys through dawn Tuesday, as well. Used the CONSShort as the starting point for all the grids with adjustments tonight and, to a lesser extent, Monday night for ridge and valley distinctions. Also, tweaked the blended guidance PoP grids to allow for more of a lingering threat of convection through the day Monday, mainly in the northeast. .LONG TERM...(Tuesday through Sunday) Issued at 400 PM EDT SUN JUL 9 2017 As the period starts, we should be positioned near the southern edge of the prevailing westerlies aloft, with a surface ridge over the southeast CONUS. A cold front is expected to be heading south into the Ohio Valley. With the flow being zonal, the front will lose momentum as it approaches. Models show some discrepancy as to how far south it will make it, with the NAM being most progressive, and the ECMWF the least. In light of the various scenarios, the southern part of the area was kept dry, with low POPs in our northern counties Tuesday into Tuesday night. A low pressure system tracking east over the Great Lakes region on Wednesday should draw the front back north, leaving us without any significant features to support precip. Mid-upper levels are expected to be fairly dry, with the deeper tropical moisture to our south. That being the case, it`s a dry forecast area wide at this point for Wednesday and Wednesday night. Models show a cold front dropping south into our area Thursday and Friday, trailing from the departing aforementioned storm system. A synoptic scale upper trough is also expected to amplify over the eastern CONUS late in the week. Models disagree on how deep the trough becomes and how effectively we dry out behind this front, as well as the potential for another cold front on Sunday. However, there is enough overlap in their solutions to focus the highest POP on Thursday night at this point. Much lower POPs have been use from Friday night trough the weekend, pending better agreement in the models as the time period draws closer. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) ISSUED AT 745 PM EDT SUN JUL 9 2017 For the bulk of the TAF period VFR conditions will prevail at all sites. However, some patchy fog may affect SME towards dawn and a tempo for BR was continued in its TAF. Will also need to watch for any lower clouds, or even the potential for a shower or storm, intruding from the north Monday morning at SYM as an cluster of convection could be passing by through southern Ohio per the latest NAM12 and now HRRR solution. Will monitor this threat and address it as needed in future updates. Winds will be light and variable through the period - outside of any stray storms. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GREIF SHORT TERM...GREIF LONG TERM...HAL AVIATION...GREIF
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
923 PM CDT Sun Jul 9 2017 .UPDATE... 923 PM CDT Evening Update... Convection had taken a bit longer to initiate over western/central MN late this afternoon/early this evening than earlier CAM guidance had depicted. Not surprisingly, the overall trend in HRRR runs (and new 00Z NAM) has been to slow the southeastward evolution of evolving MCS a bit later tonight, to beyond 2-3 am. Some runs do depict some convective development ahead of the main line however, with warm advection wing elevated storms depicted over parts of northeast IL, southeast WI or Lake MI. Very late night diurnal timing perhaps supports a lower overall severe threat, and SPC has trimmed the enhanced risk out of the cwa to the northwest. Still, development of low level jet should aid in spreading reservoir of 2000-3000 J/kg MUCAPEs across the region within region of 40-50 kt effective bulk shear, which should still support a severe potential for hail and isolated damaging wind from stronger cores and with the eventual arrival of the linear MCS late tonight/early Mon AM. Overall messaging remains similar other than the slightly later timing and slightly lower widespread severe threat. Otherwise, a couple of isolated storms over southeast cwa had shown some intensification with mid-level rotation earlier, though these are weakening now after sunset. Have made updates to hourly pop/wx grids based on radar trends in our southeast this evening, and have slowed up pop increase from MN storms a couple of hours. Otherwise, forecast appears generally on track. Ratzer && .SHORT TERM... 200 PM CDT Through Mid-day Monday... Afternoon satellite pictures reflect the surface analysis of increasing low level moisture which is advecting in from the southwest this afternoon. A cumulus field is blossoming along and ahead of this moisture gradient. Instability has build significantly in this area, but there has been limited forcing to this point. There is some weak forcing passing through in the northwest flow aloft that look to kick off a few largely isolated to maybe widely scattered showers and or storms south and west of the Chicago metro area. DCAPE will increase ahead of this wave such that gusty winds, brief heavy downpours are possible, with CAPE in the hail layer but somewhat weak shear indicating a lower hail concern. Focus will shift to the overnight hours. Temperatures will fall initially but will slow the decline this evening and increasing humidity will continue its northeastward progress into northeast IL and northwest IL. This will maintain instability out ahead of an upper level disturbance across the Upper Midwest. Earlier forecast soundings depict an impressive wind field aloft ahead of this disturbance. The low level wind field being from the southwest and increasing overnight will also maintain ample instability ahead of the wave. Short term guidance has been in relatively good agreement in developing a complex of thunderstorms across central MN this afternoon. There is also good agreement this system will likely evolve into a line of storms, with the main hazard being damaging winds, though some hail and heavy rain may also occur. The main timing will be after 12-1 am across north central IL, and spreading to the Chicago area around 2-3 am or so before continuing to the southeast. The main push of the line will be through the remainder of the area by 7 am. SPC outlook has expanded the Enhanced risk (or locally highest risk) across north central IL. The main upper wave does pass along our northern tier which would limit the upper support for the MCS farther southeast, but the Slight risk does extend through most of the Chicago area, thus expect at least some scattered stronger winds farther south, as the MCS parameters remain favorable at least into portions of northern IL for the expansion of the severe concerns, with most areas expected to get in on at least some thunder activity during the overnight hours, lingering a bit longer into the morning rush across northwest Indiana. There should be a lull in activity in wake of the MCS, but guidance does shift winds back to SW and indicates atmospheric recoveries will set the stage for more thunderstorms for some areas later in the day. More discussion on this portion of the forecast to come, but a Slight risk has been added for the southern third of the area at this point (I-80 corridor southward) KMD && .LONG TERM... 237 PM CDT Monday Afternoon through Sunday... An increasingly muggy air mass over the area Monday afternoon will be undergoing recovery after the aforementioned MCS. Surface low pressure around 1006 mb is expected to be located in the IA/IL border area by mid-afternoon, though a fair amount of uncertainty on the latitude of this feature, which along with solar insolation will determine how far north air mass recovery will occur. Southwest surface winds ahead of the low gusting to 25 mph should advect an increasingly buoyant air mass up to and even north of the outflow boundary(ies) from the morning convection, with dew points in the lower to mid 70s and temperatures probably to bounce back into the mid to upper 80s areawide (assuming onshore morning flow turns back offshore). Even lower 90s, with head index around 100, could spread into the southern/southwestern forecast area. Model guidance shows fair spread on placement and re-initiation time of convection, but it does generally agree on storm development in a west-southwest to east-northeast corridor associated with the outflow/modulated frontal boundary across the forecast area during the mid-afternoon through early evening. At least scattered storms focused on this convergence make sense with convective temperatures in the upper 80s especially if a subtle mid level short wave moves over the area as advertised by a majority of guidance. The axis most favored for late day redevelopment would be along or slightly north of the northern edge of the current SPC Day 2 Slight Risk. High values of MLCAPE of 2000-3500 J/kg and modest deep layer shear of 25-35 kt would support organized storms, with ample amount of that shear in the 1-3 km layer, supporting some rotating updrafts aiding in large hail. Even significant (larger than golf ball size) hail would seem possible with any supercell storms that can develop during or shortly after peak heating, assuming the model handle on the environment south of the outflow affected region is correct. Storm motion should be substantially slower than the late tonight activity, warranting concerns for heavy rainfall and localized flash flooding given rich column moisture. Any storms that do develop should evolve slowly southeast, possibly with some multi-cell induced cold pools. By Tuesday morning this should be draped along/near the southern CWA edge. Guidance spread is large on how quickly this front progresses north and how active it is on Tuesday and Tuesday night. Spread chances of storms back north. As an upper trough digs into eastern Canada during midweek, surface low pressure around 1006 mb will move east into the Great Lakes on Wednesday, with its warm sector likely maximized over the area that day, supporting lower to mid 90s. Associated instability ahead of the system cold front will support a regional risk of scattered strong to severe storms given the fast-paced mid-level winds. Global guidance and the GFS ensemble agree that the rich low- level theta-e air will be shunted south by Thursday, though possibly not very far so certainly within the envelope of uncertainty that the southern forecast area could have continued storm chances late in the week. Slightly less active northwest flow forecast though may support a less active period from then into next weekend. MTF && .AVIATION... For the 00Z TAFs... 634 pm...Main forecast concern is thunderstorms early Monday morning and again Monday afternoon. Thunderstorms are expected to develop over central MN over the next few hours and quickly spreading southeast late this evening reaching the terminals during the predawn hours Monday morning. Confidence on timing is only medium so maintained timing from previous forecast. Some tweaks to timing are possible with the 03z tafs. These storms are likely to have a wind shift/outflow with them...shifting winds to the north/northwest. Behind this line of thunderstorms...winds will likely be erratic for a few hours... possibly starting east or southeast then turning back southwest by mid morning Monday. A weak area of low pressure will move across the area Monday afternoon into Monday evening and is likely to trigger additional thunderstorm development across northeast IL and over southern Lake Michigan in the mid/late afternoon. Confidence is only medium on location and timing but opted to change mention to tempo with this forecast. These thunderstorms are expected to push an outflow/wind shift to the northeast across the Chicago terminals during the late afternoon. Confidence is high for a wind shift to the northeast...but timing will need to be adjusted as trends emerge later Monday. Once these thunderstorms move east/southeast of the terminals...the rest of Monday evening is expected to be dry. Southwest winds may remain in the 10-15kt range this evening turning more southerly ahead of the storms. In between storms on Monday...southwesterly winds may become gusty for a time and then turn more westerly or northwesterly before the shift to the northeast noted above. Behind the first line of storms Monday morning...there could be a period of mvfr cigs and possibly some light fog. And behind the second line of storms Monday afternoon into Monday evening... there could be a better chance for mvfr cigs especially into Monday night as the surface low departs with moist low levels and light winds. cms && .MARINE... 251 PM CDT The concerns with the Lake Michigan forecast are 1.) likely thunderstorms over the southern part of the lake late tonight into early Monday morning and 2.) winds shifting north on Monday. Southerly winds will continue for a bulk of tonight, with storms expected to develop across Minnesota and track across southern Wisconsin and northern Illinois. Southern Lake Michigan may only get a glancing blow with these storms, however they should be gusty nonetheless, and could have some gusts over 35 kt including in the Illinois and Indiana nearshore between 3 am and 7 am. Behind these storms, the winds will briefly shift northwest over the southern part of the lake, before probably some variability mid to late morning. As a front drops south across the lake on Monday winds will turn north for good, likely from north to south. The frontal boundary will retreat north Tuesday night into Wednesday ahead of low pressure which will move east across the central part of the lake midday to later Wednesday. MTF && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...None. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSCHICAGO WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
1039 PM EDT Sun Jul 9 2017 .SYNOPSIS... An inland surface trough and the Bermuda High will be the main features for this week. A cold front will approach from the northwest next weekend. && .NEAR TERM /UNTIL 7 AM MONDAY MORNING/... As of 1030 pm Sun...Thunderstorms from earlier tonight have weakened or moved out of our area. The latest HRRR continues to have a good handle on the overnight and will let our forecast stand. After a lull the next few hours, an area of showers with thunder now southwest of Wilmington will gradually spread northeast and impact especially coastal areas. Precip chances will drop off especially the farther inland you live. Lows range from the lower 70s well inland to upper 70s Outer Banks. && .SHORT TERM /7 AM MONDAY MORNING THROUGH 6 PM MONDAY/... As of 3 pm Sun...In place of the dissipated front, the typical mid-state surface trof sets up once again with the Bermuda High offshore. With deeper moisture axis and short wave shear axis lingering across area, models continue to indicate scattered to broken coverage of convective activity with greatest coverage along the coast and keeping POPs mainly in 30-50% range. && .LONG TERM /MONDAY NIGHT THROUGH SUNDAY/... As of 330 PM Sunday...Guidance remains in good agreement and continuity during period with return to more zonal flow aloft midweek followed by troughing and cold frontal intrusion Friday-Sunday. Only significant change to previous forecast was to drop POPs Wed night with all models indicating no precip. Monday night through Tuesday night...Mean upper trough over the eastern CONUS will gradually weaken during period with stalled surface boundary dissipating across area. With deeper moisture axis and short wave shear axis persisting across area, models continue to indicate scattered to broken coverage of convective activity with greatest coverage along the coast and keeping POPs mainly in 30-50% range. Temps near normal Monday night, then a couple degrees warmer Tuesday with building heights. Wednesday through Thursday...Models continue to show ridging/zonal flow for Wed-Thu resulting in return of offshore high/inland trough pattern, leading to warmer temps and less coverage of convective activity. POPs will reflect typical 20% coast and 30 to 40% inland during the day and slight chance at night. Thicknesses peak this period around 1420-1430m supporting highs in the mid 90s inland and upper 80s to around 90 along the coast. Heat indices are expected to reach 100-105 each afternoon. Friday through Saturday...Shortwave energy digs across the Great Lakes and across the mid-Atlantic States late in the week with an attendant cold front approaching the region from the northwest which will bring increased chance of tstms all zones for Friday into Saturday. Latest GFS and ECMWF in general agreement that front will move into area Saturday and then quickly wash out Sunday. Temps expected to be a couple degrees cooler with highs around 90 inland to mid to upper 80s coast. && .AVIATION /03Z MONDAY THROUGH FRIDAY/... Short Term /thru Mon/... As of 740 pm Sunday...Generally VFR through the forecast period outside of convection. Included some brief IFR at KISO over the next hour with storms to the southwest of the terminal now. As this area of storms dies down after 03Z, expect mainly VFR overnight with higher chances for thunderstorms closer to the coast. There should be enough high cloudiness around tonight to preclude most fog/stratus but a few patches may occur if clouds thin again early in the morning, but not enough confidence to include at this time. Thunderstorms are again possible all terminals from mid morning on Monday. Long Term /Monday night through Friday/... As of 330 PM Sunday...Pred VFR conditions at the terminals expected through the long term, but there will bouts of sub VFR conditions in showers/thunderstorms. There will also be occasional sub-VFR conditions during the early morning hours with the threat for stratus and/or fog. && .MARINE... Short Term /thru Mon/ As of 1030 pm Sun...Latest obs show waves 2 to 3 feet and southwest winds 10 to 15 kts, with our forecast in good shape. Mostly light winds and seas through the short term with the Bermuda High the main feature. Southwest winds will average 5-10 knots on the rivers, and 10-15 knots on the coastal waters with seas averaging 2-4 feet. Long Term /Monday night through Friday/... As of 330 PM Sunday...Surface pattern will return to offshore high and inland trough pattern through rest of week. Expect S/SW winds around 10-20 kt and seas generally around 2 to 4 ft but could build up to 5 ft at times across the outer coastal waters. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...None. MARINE...None. && $$ SYNOPSIS...HSA NEAR TERM...EH/HSA SHORT TERM...HSA LONG TERM...JBM AVIATION...JBM/EH/HSA MARINE...JBM/HSA
Area Forecast Discussion
National Weather Service Omaha/Valley NE
623 PM CDT Sun Jul 9 2017 .SHORT TERM...(Tonight through Wednesday) Issued at 330 PM CDT Sun Jul 9 2017 Forecast concerns will primarily be temperatures/oppressive heat for parts of the area/if a heat advisory is needed/frontal location and clouds too...then if/where any storms may develop. The latest visible satellite imagery shows the bulk of the cloudiness over the Upper Mississippi Valley in the warm air advection zone/mid-level omega/area north of the surface warm front. The 12Z upper air maps showed 20-40m ht falls over the Norther Plains and this area east of the h7 10deg C isotherm. At h85...low pressure was over North Dakota with a 45kt h85 jet. Locally our sounding had a pwat of 1.24 inches and elevated instability above 750mb. 20Z surface metars highlight surface low pressure over north central South Dakota with a couple of pre-frontal troughs and progressive drying/lower dewpoints. Locally temperatures were in the 90s with dewpoints in the 60s to lower 70s...however in central Nebraska the dewpoints were in the 50s and in the 30s and 40s for the Nebraska Panhandle. temperatures had warmed to 108 degrees at VTN with a northwest wind gusting to 20kts. The focus for thunderstorms tonight and Monday will be where the forcing and the moisture/instability will be most prevalent and this will be over the Upper Mississippi Valley into the Great Lakes and Ohio River Valley as the upper level jet drives shortwave energy through the h5 trof. SPC has an enhanced are for severe weather as storms develop near the surface low and is pulled high cape (5000j/kg) and northeast of the 8.5+ steep mid level lapse rates/50kts effective bulk shear vectors. Locally...ridging will develop over the Western High Plains aloft, however cooling will take place at h85 and at the surface...although this will be modified. Although cannot rule out a few isolated storms as a few showers and thunderstorms from the Black Hills/northern Nebraska tend to dissipate as they head toward the local cwa or later tonight with energy dropping south across Iowa. The CAMs are mainly dry save for the more recent HRRR lat holds on to precip toward Neligh/Albion/Columbus. The 12Z NAM12 hints at some isolated activity near SUX Monday morning along with the Canadian/SREF and the NAM/Canadian/EC/SREF/ARW/NMM have a signal near the MO/KS border Monday at 00Z. The 18Z hints at some activity similar to the more recent HRRR through 03Z this evening. Will match up with GID to include a small pop early this evening. A stronger signal Monday night with the boundary lifting north into late Monday into Tuesday. The temperature forecast for Monday has a large bust potential and will be difficult as it will depends on how strong the push is with the storm system/storms to our east and how much cloudiness develops behind the front. MOS guidance is in the 80s at KOFK and in the 80s with the MET guidance for OMA and 94 with the MAV guidance. Dropped highs across the northern parts of the forecast area, however held highs near the KS/MO border in the 95 to 100 degree range. With moist dewpoints, this pushed them into a heat advisory where heat index values of 105 t0 110 are expected. The night shift can further refine this, however in coord with TOP/EAX will issue a heat advisory for Monday. The front will be a focus for storms Monday afternoon along with the passage of a weak weather disturbance, thus for now did include chance for storms near the KS/MO border. With moisture pooled in this area and mid level warm advection and shortwave lift, overnight thunderstorms will be possible and these would continue Wednesday. .LONG TERM...(Wednesday night through Sunday) Issued at 330 PM CDT Sun Jul 9 2017 The extended has the mid tropospheric ridge anchored over the western U.S. and varying solutions as to the eastward extend of the ridge. Spotty precipitation is still in the forecast Wednesday night through Saturday...with cooler highs in the 80s for the weekend. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 622 PM CDT Sun Jul 9 2017 VFR conditions are expected through the TAF cycle, with unrestricted visibility and mid- to high-level clouds. South winds will slacken and become southwesterly this evening. Low-level wind shear is possible tonight at all sites, but particularly at KOMA/KLNK. Winds will become light and variable/shifting from Monday morning through the day. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...Heat Advisory from noon to 8 PM CDT Monday for NEZ088>093. IA...None. && $$ SHORT TERM...Zapotocny LONG TERM...Zapotocny AVIATION...Mayes