Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/10/17

Area Forecast Discussion
National Weather Service Denver/Boulder CO
628 PM MDT Tue May 9 2017 .UPDATE... Issued at 625 PM MDT Tue May 9 2017 Updated evening forecast grids to better resolve convection firing along a convergence line that radar has been showing sitting nearly stationary east-southeast of the Denver metro area past couple of hours. Strongest storm going up just southeast of KDEN has should some sign of turning northwestward and therefore may pass over the airport and northeast metro area in the next several minutes. May see a brief moderate shower and gusty winds at KDEN as it passes by. Otherwise not much else as mesoscale models show this storm activity tracking northeast rest of the evening and eventually collapsing into light showery precip on the plains. I`ve also removed mention of heavy rainfall tonight as the environment doesn`t look all that supportive for that...but still quite abit of moisture around. That said, should see skies fill and cloud bases lower after midnight as winds gradually turn north-northeast with arrival of a cold front in the denver area around 10z tonight. && .SHORT TERM...(This evening through Wednesday) Issued at 354 PM MDT Tue May 9 2017 The low pressure system centered over southern Arizona continues to drive moist southerly flow into CO. Coupled with a deformation zone developing over northern CO, there is a chance for widespread showers overnight in the CWA. The threat for severe weather has significantly decreased over the region this afternoon with the low- level cloud cover hindering convection. Main threat this afternoon into the evening is heavy rain but some small hail is still possible as sufficient CAPE and shear should remain, with highest values east of the urban corridor extending northeast into the plains. Models indicate that PW values could exceed 1 inch in some areas across the eastern portion of the CWA. This is above the 90th percentile for this time of year. This abnormally high PW will increase the threat for heavy rain, although large uncertainty exists as to where development will occur. NAM and GFS are trying to develop an MCS that moves from southern Colorado tonight north into NE CO by morning, favoring higher QPF in the area. RAP and HRRR are more reluctant to develop this feature and thus have lower QPF amounts. Nevertheless, wherever convection does develop, difluence and lower wind speeds aloft will produce slow-moving storms that could produce locally heavier amounts from 0.25-0.75 in/hour. Tomorrow, the large storm system over AZ will continue to move northeast but the low-pressure center will remain south of CO through the afternoon. Southerly moisture transport and a developing frontal boundary will be dominant factors in producing a higher chance for widespread showers throughout the day. Again, a fair amount of uncertainty exists in the forecast as models are disagreeing on where the front will develop as well as trough placement aloft and upper-level divergence. In addition, forecast soundings at this time indicate mid-level drying, which would reduce the chance for heavy precipitation. Northerly surface flow and cloud cover should keep high temperatures across the plains in the mid- to upper 50s, which is about 10 degrees below the climatological average. In the higher elevations, high temperatures will be in the upper 30s to lower 40s. Right now, snow levels are around 11,000 feet but are expected to drop to 9000-10,000 ft tomorrow in the northern foothills with some area receiving 3-7 inches of snow over the next 24 hours. .LONG TERM...(Wednesday night through Tuesday) Issued at 354 PM MDT Tue May 9 2017 Wednesday night through Thursday the slowly moving cutoff low should make it to the Oklahoma and Texas Panhandles by the afternoon, resulting in a continuation of moist upslope flow and synoptic scale lift through midday. Highest pops will be Wednesday night then taper off after sunrise. The models differ on the progression of the trough, with the ECMWF being more progressive and absorbing the trough into the NW flow by Thursday afternoon. NAM and Canadian models are slowest moving the low across N. Oklahoma Thursday afternoon...GFS is in between. Despite model differences feel the mountains and I-25 urban corridor will be dry from midday and on, while further east across the far eastern Plains the rain should exit by mid to late afternoon. Temperatures across the Plains will remain on the cool side given the remaining moisture, northeast upslope, and expected cloud cover, with temps in the upper 50s to low 60s expected across the Plains. The mountains should warm significantly compared to Wednesday given warm advection at 700 mb as the ridge approaches...700 mb temps over the mountains warm 5-7 degC over Wednesday so expect highs Thursday in the 50s and 60s. On Friday the storm is well east of the area and a ridge axis sets up directly over Colorado by Friday afternoon. Warm and dry area wide with temps in the mid 70s across the Plains and 60s and 70s in the mountains and foothills. On Saturday the ridge axis shifts east putting Colorado in southwest flow, and downsloping will boost Plains temperatures into the low 80s. Mountains temps will be similar to Friday`s readings. Some of the models generate mountain showers/thunderstorms Saturday afternoon so have including a slight chance of diurnal thunderstorms there. Do not expect rain to reach the surface east of the mountains. Sunday and Monday southwest flow continues across the state as a series of Pacific storms carves out a long wave trough across the Great Basin. Several short wave troughs rotate around the long wave trough. At this time the models indicate dry conditions state wide on Sunday as there is very little moisture to work with given trajectories from off the coast of Baja CA. Given the source of the air and lack of good moisture...warm, above average temperatures area-wide will continue Sunday and Monday. General agreement among the long range models that one of the short wave troughs brushes the northern half of the state Monday, which results in a chance of showers and thunderstorms for the northern mountains. Snow levels look to remain above 9kft Sunday and Monday. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 625 PM MDT Tue May 9 2017 Chance of t-storm with brief moderate rainfall and gusty winds at KDEN now through 0050z. Otherwise, the chance of thunderstorms in the Denver area should gradually diminish through the evening. Overnight, a cold front is forecast to slip south through the metro area around 10z. northerly winds behind the front will usher in lower clouds and light precip. Could see mvfr conditions will lower to IFR conditions after 10z at Denver area airports. && .HYDROLOGY... Issued at 354 PM MDT Tue May 9 2017 There will continue to be heavy rainfall potential from convective storms from today through Wednesday, then more stratiform rainfall late Wednesday night and Thursday. Model QPF is quite varied but still generally in the 1-2 inch rainfall range while GFS showing 2-3 inches of rainfall by late Wednesday. Slow- moving storms that could produce locally heavier amounts from 0.25-0.75 in/hour. At this time based on QPF outputs not expecting any major flooding from rainfall forecasts and current runoff projections through the end of the week. If there are more localized convective rainfall which occurs over similar areas over the next few nights, than those areas may need to be monitored closely. Two areas of concern are over northwestern Adams County, northeastern Elbert, northwestern Lincoln and southern Washington counties, as well as central Weld county near Greeley. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Baker SHORT TERM...Stovern/Kriederman LONG TERM...Schlatter AVIATION...Baker HYDROLOGY...Kriederman
Area Forecast Discussion...Updated
National Weather Service Billings MT
907 PM MDT Tue May 9 2017 .SHORT TERM...valid for Wed and Thu... Minor update to trim precipitation chances over northern and western zones. Still a few showers and working south from near Billings, heading toward the Pryor mountains. HRRR tracks these toward Sheridan in an hour or two. Precipitation over eastern zones really diminishing quickly with sunset so cut back to slight chance. Rest of the forecast on track. Chambers .LONG TERM...valid for Fri...Sat...Sun...Mon...Tue... Ridge axis will be over the forecast area to begin the extended period on Thursday. Currently have high temperatures in the low to mid 80s on Thursday and Friday afternoon while the ridge axis is overhead. This will likely bring about another round of snow melt in the mountains. Widespread flooding is not anticipated, but with higher flows already in place, we`ll likely see some small rises along area rivers and streams this coming weekend as the water works its way downstream. Good model agreement that an upper level low will begin to move into inland portions of the western US over the weekend. As this low drifts east, the ridge axis will be displaced to the east and the cooler and more unsettled weather will return to the region over the weekend. Best rain chances will be over the mountains and western zones (west of Billings and Roundup) on Saturday but then begin to affect central and eastern zones on Sunday and Monday as the low slowly slide eastwards. Temperatures will return into the upper 60s and low 70s by the weekend with increased cloud cover and higher chances for showers and thunderstorms. These seasonable temperatures should also slow the snow melt across area mountains. Looking past the weekend, model ensemble guidance and current outlooks from the CPC keep the weather fairly active across the region with above normal chances for rain and temperatures near average. The confidence in these conditions is above normal given the good agreement in the model ensemble members. Dobbs && .AVIATION... Showers and isolated thunderstorms will gradually diminish across the area this evening. Recent rain will allow fog to develop across portions of far southeast Montana overnight causing local IFR to LIFR cigs and vsbys. VCFG is possible near KMLS overnight, although confidence is low at this time. Elsewhere, VFR will prevail into Wednesday. STP && .PRELIMINARY POINT TEMP/POPS... Wed Thu Fri Sat Sun Mon Tue ----------------------------------------------------------- BIL 045/072 048/080 052/084 052/070 046/067 046/069 047/069 20/U 00/U 10/U 13/T 42/T 32/T 33/T LVM 038/072 043/078 047/080 045/066 039/064 039/066 040/067 00/U 01/U 12/T 23/T 22/T 22/T 33/T HDN 042/073 046/081 050/086 050/075 047/071 047/071 047/073 20/U 00/U 00/U 02/T 31/B 33/T 33/T MLS 044/072 048/080 052/086 053/075 050/071 049/070 050/071 10/U 00/U 00/U 01/U 31/B 35/T 43/T 4BQ 041/069 045/077 048/083 049/076 047/071 047/071 047/074 20/U 00/U 00/U 11/U 31/B 54/T 42/T BHK 039/069 044/075 047/080 046/073 046/068 045/065 046/067 10/U 00/U 00/U 00/U 31/B 44/T 44/T SHR 039/067 041/075 046/082 046/073 044/068 043/068 043/070 20/B 00/U 00/U 12/T 32/T 42/T 32/T && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...None. WY...None. && $$
Area Forecast Discussion
National Weather Service Dodge City KS
710 PM CDT Tue May 9 2017 .UPDATE... Issued at 710 PM CDT Tue May 9 2017 Updated grids through the early morning hours to reflect severe thunderstorm watch in effect for Grant, Hamilton, Kearny, Morton, Stanton and Scott counties through 2 am CDT. Not expecting much activity through 9 pm or so. HRRR solutions have been consistent with a loosly organized squall line arriving on the CO/KS border around 11 pm. HRRR shows the line of showers and storms decreasing in intensity near Garden City and Liberal by 1 am. Linear mode of convection suggests wind gusts of 50-60 mph are the primary threat, although any discrete cells along/ahead of the line may produce up to ping pong ball sized hail. && .SHORT TERM...(This evening through Wednesday) Issued at 237 PM CDT Tue May 9 2017 A couple of isolated showers have developed in the more robust updrafts over the rapidly developing cu field across southwest Kansas this afternoon. However the more numerous showers are relegated to the higher terrain area of NM/CO/TX and OK panhandles. surface upslope. Ongoing convection across the southern Rockies into the southern Colorado front range will be the primary source for convection affecting western Kansas later tonight and possibly in the overnight timeframe. Models vary considerably between the HRRR and NAM with respect to convection. The HRRR would drive storm clusters north tying into the the surface front/surface low pressure region across northwest Kansas after 02 UTC. The recent NAM runs split the area between the convective sources, holding off storm chances until Wednesday morning after 12z, associated with the southern Plains elevated convection. Additionally, the NAM develops an Elkhart surface low tied to a dryline southward across the Panhandles by the afternoon hours on Wednesday. The greatest risk from severe should be associated with this late day potential of storm developing in the far southwest, with hail greater than 2 inches, damaging wind and tornado potential. .LONG TERM...(Wednesday night through Tuesday) Issued at 237 PM CDT Tue May 9 2017 The upper low now over southern Arizona will lift into the southern High Plains Wednesday night. This should place our area in the cold conveyor belt region of the synoptic storm, with cold advection and north winds, and chances for rain showers heading through Thursday evening. This may relegates most of the area to the 60s on Thursday at most, or even cooler 50s following the much cooler NAM and ECMWF. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 600 PM CDT Tue May 9 2017 Concerns this TAF forecast period are convection and MVFR stratus. Thunderstorms across SE Colorado and NE New Mexico at 23z will progress slowly eastward into SW KS overnight. Followed the latest HRRR solution closely, which depicts a loosely organized squall line arriving on the KS/CO border around 04z, near LBL and GCK around 06z, with remnant -SHRA near DDC through about 09z. Gusty outflow winds to 40 kts may occur with the more organized line segments. MVFR stratus cigs are expected at DDC, LBL and P28 during the 06-12z Wed timeframe. Kept cigs in the VFR category at HYS and GCK. South winds near 10 kts will prevail overnight outside of convection. After 15z Wed, SE winds of 15-25 kts expected at all airports. && .PRELIMINARY POINT TEMPS/POPS... DDC 59 78 53 67 / 40 40 50 40 GCK 57 77 51 63 / 60 50 50 50 EHA 54 75 48 63 / 60 50 30 30 LBL 56 77 50 66 / 60 50 40 30 HYS 60 78 54 63 / 20 50 70 50 P28 61 80 56 73 / 30 50 40 40 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Turner SHORT TERM...Russell LONG TERM...Russell AVIATION...Turner
Area Forecast Discussion...UPDATED
National Weather Service Fort Worth TX
948 PM CDT Tue May 9 2017 .UPDATE... The previous forecast is in good shape. The only changes made were to adjust first period hourly temperature/dewpoints and to bump up the winds a little for tomorrow based on the latest model runs. && .AVIATION... /ISSUED 659 PM CDT Tue May 9 2017/ Isolated showers mainly southeast of a KTPL-KF44 line will dissipate by 03z and are not expected to affect the TAF sites. VFR conditions are expected this evening. Expect MVFR ceilings to spread north overnight tonight reaching KACT around 07z and the Metroplex sites around 08z. Ceilings should lower into the IFR category at KACT around 08z and hang in through 18z and may be in the Metroplex during the 13z to 16z period. There will be a low chance of showers and thunderstorms Wednesday afternoon and evening, but the chances at the TAF sites is too to include at this time. 58 && .PREV DISCUSSION... /ISSUED 343 PM CDT Tue May 9 2017/ Several days of southerly low-level winds have finally managed to advect richer moisture across Texas, with dewpoints this hour running in the lower 60s near the Red River, and the upper 60s to near 70 across our southern counties. Showers and thunderstorms have been developing across the Texas Hill Country, on the eastern periphery of a low-level theta-e ridge amidst a region of lingering warm advection. Thus far, convection has remained quite tame, and is likely still feeling the effects of lingering dry and warm air in the mid-levels based on latest RAP point soundings. Given limited forcing for ascent (the parent upper-low is still well off to the west and dropping into Sonora, Mexico), overall shower/storm coverage should remain isolated to scattered this afternoon, with the greatest coverage expected generally south of a Lampasas to Palestine line. Any lingering activity will then gradually fizzle this evening with the loss of daytime heating. Given the presence of lingering dry and warm mid-level air, the threat for any strong or severe storms remains quite low at this juncture. As the aformentioned upper level low pinwheels into New Mexico this evening, additional showers and thunderstorms are expected to develop well to our west. These will eventually congeal into an MCS that will track towards the Texas Big Country overnight. The current anticipation is that these storms will gradually wane as they encounter increasing nocturnal inhibition and a veering low- level wind field. However, it`s possible that this decaying activity lays down an outflow boundary that may play a role in our convective chances on Wednesday. The upper low will finally begin to emerge across the Texas Panhandle on Wednesday, and this added impetus will allow a surface dryline to mix just west of our CWA during the afternoon. The combination of this dryline and any remnant outflow from overnight storms could serve as foci for convective development perhaps as early as late-morning as the eastern fringes of ascent from the low approach. Deep layer shear values approaching 40-50 kts combined with a moderately unstable atmosphere with MLCAPEs approaching 1500 J/kg and steep mid-level lapse rates of 7.5-8.5 C/km mean storms will pose a risk for large hail and strong wind gusts. The tornado threat appears LOW and will largely be tempered by weaker flow in the 0-1 km layer. That said, the presence of backed surface winds and the presence of at least limited 0-1 km SRH suggest this potential is not zero. Indications of lingering warm and dry air aloft near the 700 mb layer do also throw a complicating factor into the forecast for Wednesday, as this may tend to limit storm coverage/severity. As a result, we`ll carry 20-30% PoPs (highest along and west of I-35/35W) given this lingering uncertainty. Storms should march eastward, encroaching on the I-35 corridor during the mid to late afternoon, before diminishing in coverage/intensity during the evening as they outpace the better ascent and encounter increasing inhibition. We`ll continue to show low precipitation chances across our western counties overnight Wednesday as activity may continue near the dryline. On Thursday, latest indications are that the dryline may actually begin to mix into our northwestern counties before inhibition erodes sufficiently to allow the next round of storms to fire during the afternoon. As a result, we`ve pared back PoPs Thursday afternoon to locations east of a Comanche to Mineral Wells to Bowie line. The thermodynamic/kinematic environment will once again support severe thunderstorms with a large hail and downburst wind threat as DCAPE increases past 1000 J/kg. The propensity for surface winds to veer ahead of the approaching dryline/cold front will once again help temper the overall tornado threat, but we`ll need to keep an eye on any localized backing to the flow, which simply cannot be pinpointed this far our. Activity will come to an end for us on Thursday night as a cold front sweeps through the region, leading to yet another nice weekend. Southerly flow will be quick to return, however, and by early next week, low precipitation chances will begin to return to portions of North and Central Texas. Carlaw && .PRELIMINARY POINT TEMPS/POPS... Dallas-Ft. Worth 69 82 70 86 64 / 10 20 20 40 30 Waco 69 83 70 85 63 / 20 20 20 30 20 Paris 65 81 66 80 62 / 5 20 10 60 60 Denton 67 80 68 85 61 / 10 30 20 40 20 McKinney 66 80 68 84 62 / 10 20 10 50 40 Dallas 69 82 71 87 65 / 10 20 10 50 30 Terrell 66 81 68 84 63 / 10 20 10 60 40 Corsicana 68 84 69 84 64 / 20 20 10 50 30 Temple 69 84 69 85 64 / 20 20 20 30 20 Mineral Wells 67 80 65 87 60 / 10 30 20 20 10 && .FWD WATCHES/WARNINGS/ADVISORIES... None. && $$
Area Forecast Discussion
National Weather Service Goodland KS
516 PM MDT Tue May 9 2017 .SHORT TERM...(This afternoon through Wednesday) Issued at 240 PM MDT Tue May 9 2017 Closed upper low is still centered near the Arizona/Mexico border with diffluent southwest flow over the Southern Plains extending into the Central Rockies and Central High Plains. A stalled front is beginning to lift north as a warm front wind is now orientated just south of Interstate 70. This afternoon-Tonight: Shortwave trough currently rotating around eastern periphery of closed low will continue to move over eastern Colorado with large scale ascent and deep plume of moisture spreading towards our CWA. Thunderstorm activity should initially be in eastern Colorado, though I can`t rule out isolated activity along frontal zone (hinted at by some short range guidance). Models continue to favor increasing coverage from the west, with propagating eastward along frontal zone (likely dependent on cold pool development). Deep shear is already in place with effective shear values shown by RAP in the 40kt+ range. Instability is still building and this may be the biggest question mark for most of our CWA due to impacts of cloud cover. Models are showing max CAPE values in excess of 1500 J/KG by 6 PM MDT which is adequate, but trends haven`t matched up yet. Another consideration is potential for enhanced low level shear along frontal zone that could support tornado development (particularly in our west), but this still seems conditional on more discreet cells in this region (current trend is towards clusters. Early in the event (over eastern Colorado) we may see thunderstorms training and this could support a better chance for flash flooding. Storm motions are generally going to be 30kt or higher, so flood threat will be more localized and limited to early part of the event tonight. Wednesday: Models show a region of subsidence/dry slot shifting over our CWA during the morning hours before large scale ascent overspreads our CWA during the afternoon. Expect shower and thunderstorm coverage to increase across the area through the afternoon. Front will push back south shifting main axis of instability with it, but we may still see a limited severe threat with lingering elevated instability. A greater concern will be the slow storm motions and potential for back building of thunderstorms that could create a better threat for flash flooding than today. .LONG TERM...(Wednesday night through Tuesday) Issued at 220 PM MDT Tue May 9 2017 Thunderstorms and rain will start off the extended period due to a closed low pressure system continuing its way northeast towards the CWA. Wednesday night will likely be the ideal time for storms to develop as instability is the best. But, as the overnight hours progress the instability factors start to diminish and most of the precipitation turns to rain (with isolated lightning possible). Thursday, the closed low shifts east before moving over the CWA and skirts to the south of the area. This will keep most of the instability to the south and continue rain chances over the area (will not rule out isolated non-severe storms though). The rain is expected to diminish through the afternoon from northwest to southeast as the low moves southeast. By the end of the day, a ridge is expected to move into the region from the west. Friday through the weekend will primarily be dry due to the ridge sitting over the CWA. By the end of the weekend southwest flow will start to push into the region and bring moisture into the area. This is due to a trough developing over the Pacific Northwest. Monday will be a day to keep an eye on due to an upper level shortwave trough looking to move through the trough and over the region. This could potentially bring thunderstorm chances to portions of the area (current guidance is showing along and north of Interstate 70). Tuesday looks to dry out again with that shortwave moving northeast of the region. Temperatures during the period will be in the 50s/60s on Thursday due to the region being on the back side of that trough. Friday will increase into to the 70s. The weekend through Tuesday will be in the 80s, with Tuesday seeing some decreasing temperatures along the northwest portion of the region. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 454 PM MDT Tue May 9 2017 Main issue will be the expected storms spreading east across the forecast area this evening and overnight behind the advancing cold front. There maybe enough elevated instability for the severe threat to continue past 6z. KGLD would have the most prolonged window for severe storms. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...DR LONG TERM...CLT AVIATION...JTL
Area Forecast Discussion
National Weather Service Indianapolis IN
1155 PM EDT Tue May 9 2017 .UPDATE... The Aviation section has been updated below. && .SYNOPSIS... Issued at 208 PM EDT Tue May 9 2017 A weak area of Low pressure will exit Central Indiana this evening. In its wake...a frontal boundary will be left across Indiana...and this will be the focus for weather over the next several days. Mainly dry weather is expected tonight as weak high pressure arrives in the area along with the lingering front. Much of Wednesday should remain dry across Central Indiana...however as the day progresses...chances for showers and storms will increase. Daytime heating along with the arrival of an upper level disturbance on Wednesday Night is expected to lead to more rain. The front will continue to linger across Central Indiana through Friday...bringing occasional showers or storms to the area through the end of the work week. High pressure is expected to arrive this weekend...bringing a return of dry weather and near normal temperatures. && .NEAR TERM /Today/... Issued at 1002 PM EDT Tue May 9 2017 Going forecast in fairly good shape. Did remove remainder of pops and thunder for the night as no signs of development noted. Made minor adjustment to increase temp gradient overnight across the quasistationary boundary. Will leave fog mention as patchy as HRRR visibilities are not very aggressive at all with fog overnight, and ongoing stratus north of the boundary may limit the fog development, but the outside potential will remain for some dense fog near daybreak Wednesday. Previous discussion follows. Issued at 208 PM EDT Tue May 9 2017 Surface analysis early this afternoon shows an area of weak low pressure over Central Illinois. A warm front extended southeast from the low across Central Indiana. Large difference were found on each side of the seen with temps in the 50s at Muncie and Indianapolis...and 60s and 70s on the south side at Bloomington...Terre Haute and Vincennes. The morning showers and storms appear to have all but ended...except for a quickly departing showers near Greensburg and North Vernon. Main forecast challenge tonight will be pops. GFS suggests the surface front will remain along and near I-74. Aloft...minimal forcing appears to prevail as ridging builds aloft. Time heights and forecast soundings show saturated lower levels along and near the front tonight...but with minimal forcing. Mid and upper levels appear dry beneath the ridging aloft. Thus confidence for precip will be low. However given the available lower level moisture along the front and weak lower level convergence expected...some very light rain or drizzle cannot be ruled out...but confidence for measurable precip is low. Furthermore...fog overnight...particularly on the north side of the front will be expected...given the ample moisture and weak winds. Given the expected clouds...will trend low warmer than a blend. && .SHORT TERM /Wednesday through Friday/... Issued at 208 PM EDT Tue May 9 2017 Similar features remain in place on Wednesday morning as compared to the overnight period. Plenty of lower level moisture remains present amid minimal forcing. Thus will expect a slow burn off of morning clouds and fog...and again. Better forcing begins to arrive on Wednesday afternoon as the GFS suggest a short wave arriving in the late afternoon. Forecast soundings suggest convective temps in the upper 70s which should be reached on the warm side of the front...and elevated convection appears possible near the front above the surface inversion. Thus will trend pops upward during the late afternoon hours as more organized forcing along with daytime heating. A blend on temps will work well. Highest confidence for precip during this period will be Wednesday Night as best short wave dynamics arrive aloft...riding the ridge. With the surface front providing lower level convergence and force soundings showing deep saturation...again...confidence is high. Thus will trend pops higher on Wednesday night. Again...given the expected clouds and rain will trend lows at or above the blend. GFS and NAM suggest more upper level dynamics poised to push across Indiana on Thursday through Friday. The upper low over the western plains continues to suggest short wave energy will be ejected from the system and stream across Indiana...providing lift. Meanwhile in the lower levels...little will have changed. The frontal boundary looks to remain across Indiana...providing a focus for development and lower level convergence. Thus periods of showers and storms appear quite reasonable on Thursday through Friday. Forecast soundings continue to suggest deep saturation through the period with pwats ranging from 1.25 to 1.50. Although this should not be as heavy as previous rains...the long duration of the precip and possible isolated heavier rains could result in additional flooding over Indiana`s already saturated grounds. Thus through the period we will continue to trend pops highs...highs cooler than the blend and lows warmer. As just stated...will be watching closely the progression of these systems for flooding threats. && .LONG TERM /Friday Night through Tuesday/... Issued at 233 PM EDT Tue May 9 2017 The blocky upper level pattern that has dominated the weather across the lower 48 so far this month is showing no signs of breaking...just yet. With that being said...a subtle shift in positioning of the dual upper lows over the western and eastern parts of the country will lead to a change in weather across the Ohio Valley and central Indiana for the weekend trending towards primarily dry and more seasonable for mid May. The front responsible for the unsettled weather this week will be departing away from the region late Friday with a surface high pressure ridge predominantly in control for the weekend. Extended model consensus still favoring low pressure tracking through the Great lakes late Saturday into Sunday associated with another piece of energy aloft diving into the eastern trough. Recent trends have been shifting primary impacts from this feature more north and east of the forecast area with only a small chance for a shower Saturday night over northeast counties. The amplifying upper low setting up over New England will help to spin up a deep surface low off the northeast coast by early next week. Central Indiana and the Ohio Valley will remain far enough west for little to no impact from this system...other than maintaining a blocky pattern that will last for much of next week with only small chances for rain through the middle of next week. Low level thermals are supportive of more normal temperatures for this time of year with highs likely to be in the 70s for most throughout the extended. With cyclonic flow present...dewpoints will be lower than average keeping humidities low as well. Enjoy this brief reprieve as signs do exist on the horizon for a shift back to a more active pattern by late next week as the western trough kicks east and the stagnant upper level pattern begins to break down. && .AVIATION /Discussion for the 10/06Z TAFs/... Issued at 1155 PM EDT Tue May 9 2017 VFR initially will give way to MVFR at most sites and perhaps some IFR at IND and LAF as a quasistationary front remains in the area overnight into Wednesday. Ample low level moisture is in place with a sharp low level inversion expected to develop overnight north of the boundary. Sites likely to be along and north of the boundary (IND and LAF) will be most likely to see IFR. HUF and BMG will likely see some brief MVFR at best. Winds will be low confidence particularly in proximity to the boundary, and will likely be variable at many if not most of the sites overnight. Conditions will show some improvement from mid morning on tomorrow. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS...Puma NEAR TERM...Puma/NIELD SHORT TERM...Puma LONG TERM...Ryan AVIATION...NIELD
Area Forecast Discussion
National Weather Service Riverton WY
330 PM MDT Tue May 9 2017 .SHORT TERM...(This evening through Friday) Issued at 200 PM MDT Tue May 9 2017 Thunderstorms have developed early this afternoon, as expected, from YNP into the western mountains, and are now moving off the higher terrain to the valleys and basins to the lee of the mountains. Brief heavy rain, small hail, and gusty wind can be expected with the storms as they continue this afternoon, and potentially remain through the mid evening hours. The HRRR continues to forecast some larger stronger clusters developing off the Washakie Needles, southern end of the Bighorn Mountains, and central Sweetwater county, then moving ENE. Will watch those areas for hazardous conditions if necessary. As the shortwave trough drops southeastward over NE WY overnight, appears that an area of showers will develop after 9pm and bring light to moderate rain mainly to Johnson and Natrona counties, through 3 to 6am. Anticipating some areas of patchy fog given the low and mid-level moisture in the area, along with some clearing out by 6am as ridging starts to develop. Then conditions should improve after 9am Wednesday as the high pressure builds to our west over Idaho. Wednesday will thus see mostly clear skies with slightly warmer temperatures and a north-northeast wind as the main upper level low traverse northern NM. Thursday will see the ridge axis move overhead, although 700mb temps only look to reach the 4 to 8C range allowing surface temps to reach 70 to 80 across the lower elevations. As the ridge axis moves to the WY/NE/SD border on Friday and strengthens, western and central WY should see an increase in southerly flow along with lightly warmer temperatures. Some isolated thunderstorms may develop Friday afternoon over the Tetons and northward into YNP as another large trough sets up over the Pacific Northwest. .LONG TERM...(Friday night through Tuesday) Issued at 200 PM MDT Tue May 9 2017 The extended forecast starts with a strong ridge axis to our east and a large low pressure system in the Pacific Northwest. The initial surge of a shortwave trough with moisture appears to mainly impact eastern Idaho into SW MT Friday into Friday night, with a slight chance of showers and thunderstorms across far western WY. Saturday looks to be a continuation of this pattern as the low makes little movement to the east, although cloud cover over western WY should decrease the temps some. The wind should increase to 15-20 mph as well on Saturday. The main energy wave off the trough swings SW-NE into MT on Sunday. At this time, the model guidance does not indicate much convective activity for WY. The resulting pattern on Sunday night into Monday though is for some moisture to be drawn into WY from both the south and the east, and bringing showers and thunderstorms to much of the state. The PacNW trough then moves SE over Oregon on Tuesday, increasing the chances for showers and thunderstorms across western WY. The GFS and ECMWF are surprisingly in fairly decent agreement for much of the period, so it looks likely we`ll continue with another active weather period for the later part of the weekend into next week. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 330 PM MDT Tue May 9 2017 Scattered showers and thunderstorms will continue late this afternoon into the evenings hours, with the storms expected to diminish by 03-04Z Wed. The stronger storms will produce brief heavy rain, small hail, and wind gusts of 35-40 kts. MVFR to IFR conditions possible under and around the storms. Rain showers are expected to develop across central WY and move southeast after 06Z Wed, mainly impacting KCPR through 12Z Wed. Most higher terrain across northern and central WY will be partially obscured through 15Z Wed. Several terminals will see patchy fog during the early morning hours due to good low level moisture and some clearing skies as high pressure starts to build in. The local fog should dissipate after 15Z Wed, with mostly clear skies expected Wednesday at all sites. Winds will mostly be N NE Wednesday with some stronger gusts around KRKS up to 20 kts. && .FIRE WEATHER... Issued AT 200 PM MDT Tue May 9 2017 Weak low pressure is swinging southeastward today, along with a large system over AZ and NM, bringing low- and mid-level moisture and some instability to WY. Thunderstorms and showers have already started this afternoon and are expected to continue through 8-9pm tonight, with some of the storms producing brief heavy rain, small hail, and gusty outflow wind. Some stronger storms may traverse the southern Bighorn Basin, southern Johnson county, and eastern Sweetwater county. Some rain showers are also likely overnight over central WY before moving into SE WY. Wednesday will see clearing skies late in the morning and afternoon, with temps increasing over northern WY with RHs decreasing, but southern WY will see slightly cooler temps and higher RHs due to the large low system to the south. Thursday will be warmer and drier statewide, relatively light wind. Friday will see warm temps and stronger wind. && .RIW WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...McDonald LONG TERM...McDonald AVIATION...McDonald FIRE WEATHER...McDonald
Area Forecast Discussion
National Weather Service Blacksburg VA
924 PM EDT Tue May 9 2017 .SYNOPSIS... A warm front will continue to make very slow northeastward progress tonight, eventually stalling overnight. The front and weak disturbances acting on it will serve as the focus for active weather through the rest of the workweek. Several opportunities for showers and thunderstorms through that period, with the wettest conditions expected on Thursday and Friday. A return to a drier weather pattern is expected for the weekend. && .NEAR TERM /THROUGH WEDNESDAY/... As of 915 PM EDT Tuesday... Multiple bands of showers and stronger thunderstorms continue to evolve northeast across the region ahead of a stalled boundary across the southwest this evening. Latest soundings show much of this more of an elevated nature per multiple inversions while aided by strong directional shear aloft. This basically over a more stable layer heading east of the I-77 corridor where thinking more of a heavy rain threat at least over the next few hours. Thus have upped pops across the region given translation of convection from southwest to northeast via bands ahead of the boundary that should lift a bit more into the area late. Latest HRRR suggests that coverage should finally fade a bit after midnight as energy aloft pivots over the ridge but appears will still be a band of showers around central zones through daybreak. Otherwise only small tweaks to the going temps overnight with moisture on the increase per muggy dewpoints and PWATS over an inch off soundings this evening. Previous discussion as of 336 PM EDT Tuesday... Northwest to southeast oriented surface warm front continues to bisect the forecast area, extending from southeast IN southeastward into the NC Piedmont area. Complex mid-level pattern exists with upper low centered over northern New England and mid-level ridge over the mid-Mississippi Valley; gradient between the two synoptic features implies a fast belt of mid-level northwest flow across the central Appalachians. While earlier rain showers this morning have dwindled, upstream regional radar shows a re-development of steadier showers and embedded thunderstorms over northeast KY into the Cincinnati area, with lighter showers in more stable air across central WV. For the rest of the afternoon/tonight: Warm front will continue to progress very slowly northeast through overnight. How far northeast the front ultimately makes it is still in some question, especially with rain falling into the cool side of the boundary. Through the afternoon and early evening, expect ongoing rain to progress into an area roughly bounded between I-64 and I-77. High-resolution guidance consensus suggests ongoing thunderstorms in eastern KY may brush areas west of I-77, but likely in a weakened state as instability is quite low in this area, at or below 1000 J/kg MUCAPE per SPC mesoanalysis. Later tonight and overnight, rain should be primarily focused northeast of I-77. This should be a decent rainfall but not thinking this would cause any significant issues. Shown lows in the upper 40s to low 50s along the I-64 corridor, mid 50s for the central VA piedmont, Roanoke and New River Valleys, and the mid/upper 50s for the NC Piedmont, southern Blue Ridge and Mountain Empire region in VA. For Wednesday: A low-confidence forecast with details heavily contingent on the position of the warm front and on any mid- level vorticity maxes that rotate around the mid-level ridge. Current indications are that the warm front will have lifted far enough northeast to allow a warm sector to extend from central WV southeastward into northeast NC, with cooler/cloudier conditions northeast from that line. Steep low to mid-level lapse rates are likely in the warm sector with Showalter indices likely in the -1 to -3C range, resulting in MUCAPES on the order of 1500-2000 J/kg on the bullish NAM. In a capped air mass and without any significant source of larger-scale lift, could only go with slight to low Chance PoP wording for Wednesday afternoon. 3-km NAM and the WRFs only depict isolated coverage tomorrow afternoon and mainly along and south of a Blacksburg to Danville line. Present SPC outlook for Day 2 shows General thunder with the extreme eastern extent of the 5% severe/Marginal Risk area extending on the VA/KY border. Cloud- cooled upper 60s to mid 70s forecast along and north of route 460, with mid/upper 70s to low 80s in the warm sector. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/... As of 336 PM EDT Tuesday... During this portion of the forecast, we anticipate the frontal boundary that will have been stalled across the region to make headway northward as a warm front. This will be in response to a strengthening upper level ridge immediately upstream across the Lower Ohio Valley. Not much more than twelve to eighteen hours after this shift north of the baroclinic zone will we be watching for another change in our overall pattern. The closed upper low/trough that was across the Central Plains states will start arriving in the Lower Ohio Valley by Friday. This feature will add increased jet dynamics across the area during the day Friday, and then cross the region Friday night. The result of this transition will be a trend for the best coverage of precipitation to be across the northern and eastern sections of the region by Thursday night. This will be a shift north from the expected scenario on Wednesday night of the precipitation bisecting the region along a NW-SE orientation. Friday into Friday night, the degree of coverage of precipitation will be on the increase with the best coverage first across the western half of the area, but spread eastward during the afternoon and evening hours. Please reference the HYDROLOGY section of this discussion for details on expected rainfall and hydrologic concerns. Temperatures during this portion of the forecast will have daily fluctuations a little above to a little below normal for this time of year. && .LONG TERM /SATURDAY THROUGH TUESDAY/... As of 336 PM EDT Tuesday... On Saturday, the trough axis of the upper low and associated cold front will be heading east of the region. Lingering scattered showers are expected during the day. By Saturday night the upper low is expected to be over the western Atlantic just off the New Jersey coast, centered around 38 N latitude and progress farther eastward heading into Monday. Concurrently, a broad upper ridge will develop from Texas to the Dakotas. This pattern will again place our area within a northwest flow regime. Weak disturbances within this flow may allow for some isolated upslope showers across parts of southeast West Virginia Sunday into Monday. By Tuesday, the axis of the ridge is progged to have shifted east, and be centered closer to our region. However, a shortwave trough within the northern jetstream is expected to push through the top of the ridge and suppress the ridge southward. Isolated convection is expected this day, not from upslope conditions, rather from diurnal and differential heating across the mountains. Temperatures during this portion of the forecast will be near or slightly below normal for the weekend, but trend to readings five to ten degrees above normal by Tuesday. && .AVIATION /01Z WEDNESDAY THROUGH SUNDAY/... As of 745 PM EDT Tuesday... Low confidence in specifics, medium/high confidence in trends through the TAf period. A warm front will remain draped across the region through the period. As is typical of a warm front dynamic forcing is vague but there is a good amount of shear across the boundary. Expect showers/storms through the early part of the TAF period to slide along the front with a gradual decrease overnight. This will allow cigs to descend and settle in at IFR with some fog developing as well. Cigs will lift as fog dissipates Wednesday morning. Convective cap will be present tomorrow to help suppress convection, though something may be able to fire along the boundary during the afternoon as heating helps erode the cap. However, meso guidance is generally dry so will leave TAFs dry through the latter portion of the valid period but the situation will bear watching. Winds will generally be light. Extended Aviation Discussion... A nw-se oriented frontal boundary will remain situated over or very near the region through Saturday. Expect daily chances of showers, and some thunderstorms. Areal coverage and timing of thunderstorms remain low-confidence and heavily dependent on developments further northwest. Additional prolonged periods of sub-VFR conditions are also forecast as upper level disturbances move along this boundary providing for enhanced coverage and heavier precipitation. A stronger upper low will pass over or just south of the area Friday into Saturday. Once this system passes to the east, there will be a trend towards improving conditions heading into the weekend. Confidence levels are moderate to high on the general nature of the above discussion. && .HYDROLOGY... As of 336 PM EDT Tuesday... Precipitation totals during the Wednesday night through Friday night part of the forecast will be greatest across roughly that portion of our area west of Interstate-81 and north of Route 460. By early Saturday morning rainfall totals averaging 2.00 to 2.25 inches are expected. The remaining portions of southwest Virginia and parts of north central North Carolina are expected to receive amounts more on the order of 1.33 to 2.00 inches. The Northern Mountains and Foothills of North Carolina will receive amounts more in the range of 0.75 to 1.33 inches. For all of these locations, half of this precipitation is expected to fall during the time period of Thursday through Thursday night. As the days progress, we will monitor where rain fell, how much fell, and how comparable it has been to the flash flood guidance as provided by the appropriate River Forecast Centers. The Weather Prediction Center has already posted an Excessive Rainfall Outlook for the Thursday and Thursday night time frame for the region. The area outline above with the expected highest totals in approximately the same area WPC has a slight chance for excessive rain, or 5 to 10 percent chance for rainfall exceeding flash flood guidance, with a marginal chance, or 2 to 5 percent chance of exceeding flash flood guidance, for the remainder of the region. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...AL/JH NEAR TERM...AL/JH SHORT TERM...DS/RAB LONG TERM...DS AVIATION...AL/MBS HYDROLOGY...DS
Area Forecast Discussion
National Weather Service Tulsa OK
823 PM CDT Tue May 9 2017 ...UPDATE... .DISCUSSION... Convection along the TX/NM border will make slow progress east overnight. Latest HRRR output suggests activity will be in a weakened state and may hold off until after 3-4 am (if it makes it at all). Have tweaked/delayed PoPs some after 06z otherwise forecast is in good shape. && .PRELIMINARY POINT TEMPS/POPS... TUL 67 82 64 79 / 30 40 40 60 FSM 66 86 66 81 / 10 20 40 60 MLC 65 80 65 81 / 10 30 30 50 BVO 63 81 62 78 / 30 40 40 60 FYV 62 81 63 76 / 10 20 40 70 BYV 63 83 63 76 / 10 30 40 70 MKO 64 81 64 79 / 20 40 40 60 MIO 63 81 63 78 / 30 40 40 60 F10 65 79 64 80 / 20 40 40 50 HHW 65 80 66 80 / 10 20 20 60 && .TSA WATCHES/WARNINGS/ADVISORIES... OK...None. AR...None. && $$ SHORT TERM...18 LONG TERM....99