Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/11/19

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
957 PM EDT Wed Jul 10 2019 .UPDATE... The 00Z DTX sounding tells the story of afternoon and early evening convective potential for SE Michigan. It shows a well mixed boundary layer with generous moisture supply but just not enough to break through the cap in the 800-750 mb layer. A few late developing updrafts made an attempt but quickly dissipated while storms developed more fully to the east where moisture was deeper and much more strongly to the south where surface based instability was greater. For the rest of tonight, thunderstorm potential shifts to the upper level trough and surface cold front moving across the northern and western Great Lakes. A window for storms remains open for SE Michigan as the mid level thermal trough is nudged eastward and replaced by modest cooling aloft. This is proving adequate for continued expansion over northern Lower and for new convection near the south end of Lake Michigan where slightly greater mid level lapse rate overlaps with the MLCAPE axis and stronger SW flow aloft. A secondary surge of low level theta-e ahead of the cold front is expected to maintain moderate elevated instability during the night that could support additional isolated to scattered coverage along and ahead of the cold front. Marginal and conditional is a good way to describe severe potential as storms, if they develop, are limited by the loss of surface based instability while gaining access to a slightly better wind profile. Slightly stronger shear could support a marginal hail risk along with a localized downburst wind gust and locally heavy rainfall before the front exits into Ontario toward sunrise. && .PREV DISCUSSION... Issued at 710 PM EDT Wed Jul 10 2019 AVIATION... Increased convective potential shifts to the cold front advancing from Wisconsin into Lower Michigan tonight. Southward development along the front has been limited so far but a window does remain for activity reaching the MBS to FNT area during late evening and early overnight. Conditions outside of any storms remain VFR upon passage of the initial cold front through early Thursday morning. A trailing pressure trough brings a stronger NW wind shift by late morning through Thursday afternoon. Substantial cumulus coverage is expected in the cooler but still relatively humid air mass into Thursday evening. For DTW... A stray shower or thunderstorm remains possible near the Canadian and Ohio borders through early evening moving eastward and away from DTW. Storms along the cold front also appear to remain north of DTW tonight although new development near the south end of Lake Michigan will be monitored during the evening. DTW THRESHOLD PROBABILITIES... * Low for thunderstorms tonight. * Moderate for ceiling 5000 ft or less Thursday. PREV DISCUSSION... Issued at 351 PM EDT Wed Jul 10 2019 DISCUSSION... Forecast reasoning laid out in previous discussions remains valid going into this afternoon. An instability axis is moving in from the west with latest RAP guidance indicating MLCAPEs of 1500+ J/kg present west of US-23. Weak midlevel capping in place (evidenced by lack of stronger vertical development in the cumulus field) and weak forcing will hinder much convective development, but isolated showers and storms will be possible in the 6-10pm window given the unstable air mass. 0-6km bulk shear of about 15-20 kt is currently in place and will increase to about 30 kt this evening as the low pressure system moves into northern lower Michigan, which will allow for a marginal risk of strong to severe storms. The main threats will be 50-60 mph wind gusts, small hail, and heavy rain given potential PWATs in excess of 1.5 inches. After diurnal support is lost and the boundary layer stabilizes, severe threat diminishes. However, a broken line of showers or storms ahead of the incoming cold front may extend/survive into the Saginaw Valley and Thumb tonight in the 11pm-3am time frame. Dew points in the upper 60s to lower 70s will remain in place much of the night ahead of the cold front. With cold frontal passage late in the overnight period and weak/delayed cold advection, lows will be held in the upper 60s to lower 70s as well. The overall result will be a very muggy night. Tomorrow will be a more comfortable day across the region as cooler and slightly less humid air advects in from the northwest. Mixing depths expand to around 850mb and tap into slightly elevated gradient flow, resulting in a breezy afternoon. 850mb temps around 13-15C will allow for highs to climb into the lower 80s across much of the region and mid 80s in the Detroit urban corridor and south of the glacial ridge. Isolated to widely scattered showers will be possible during the afternoon as the thermal trough passes overhead coincident with a weak surface trough. Lows tomorrow night will fall to around 60 degrees (mid 60s in Metro Detroit) with any lingering showers having tapered off by evening. Quiet weather on Friday as weak height rises move in with a ridge expanding in from the upper Midwest. Surface high pressure will build in from the mid-Mississippi Valley with light northerly flow keeping temperatures seasonable in the 80s with mostly sunny to partly cloudy skies. Saturday morning a low moves south of the Hudson Bay which brings a slight chance for some scattered storms and showers Saturday evening as its weak cold front moves across SE MI. Before the fropa, hot humid air returns to the area with Saturday highs near 90 and dewpoints in the 60`s. Post fropa highs Sunday will be average, in the mid 80`s. Another large ridge of high pressure sets up over the Great Plains and moves over SE MI by Monday bringing a very hot humid airmass. Highs the first half of the next work week will be in the low to mid 90`s and dewpoints in the mid 60`s. Though still uncertain given how far out it is, models are taking the remnants of what is currently Potential Tropical Cyclone Two up the Mississippi valley and over SE MI by Thursday next week which could bring heavy rain to the area if the track pans out. MARINE... Light wind within resident high pressure will continue through today. There is a chance for severe thunderstorms this evening mainly over the southern waters. Light to moderate northwest flow fills in behind the cold front on Thursday. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. Lake Huron...NONE. Lake St Clair...NONE. Michigan waters of Lake Erie...NONE. && $$ UPDATE.......BT AVIATION.....BT DISCUSSION...TF/KDK MARINE.......JVC You can obtain your latest National Weather Service forecasts online at
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
700 PM CDT Wed Jul 10 2019 .SHORT TERM... 1237 PM CDT Through tonight... Thunderstorm chances continue to be the main forecast question, though heat indices around 100 degrees this afternoon may be causing the bigger impacts. Regarding convective trends, most of the latest CAMs have at best some spotty development for the rest of the day into the evening, with the southeast portion of the forecast area most favored. Cumulus development is very sparse across our western half and just upstream of the area so far. This is probably related to the nose of warm air just above 800mb being seen in late morning AMDAR data and reflected in the latest RAP soundings. The RAP shows this cap eroding somewhat but not completely this afternoon, so have held onto a slight chance of storms mainly across our southeast where the cumulus field is more robust and the passing cold front will coincide with the best diurnal support. Expect that anything that does manage to develop this afternoon to wane during the evening and then dry conditions to prevail into tomorrow morning. With dewpoints in the 60s by morning rather than lower 70s like this morning, low temperatures tonight behind the cold front should also be a few degrees cooler than this morning. Lenning && .LONG TERM... 218 PM CDT Thursday through Wednesday... A relatively quiet period is setting up for the long term forecast period. The upper level pattern is transitioning to a broad low amplitude long wave pattern with an upper high parked over the Southern Rockies/Four Corners region and the western extent of the Bermuda high staying east of the Florida Peninsula. Meanwhile, a series of upper troughs will dig through the Eastern Great Lakes and southeastern Canada. Broad wnwly flow aloft will persist from Thursday into early next week. Weak shortwave energy dropping through the wnwly flow aloft may bring a few chances for some showers and thunderstorms, but with the main upper forcing shunted north of the Wisconsin border, and pcpn chances will be low, and likely be glancing the far nrn portions of the CWA. For Thursday and through the weekend, sfc high pressure will also be firmly established across the region, leading to warm, but less humid conditions. By Friday night, a weak cold front from an associated low over northern Ontario will sag southward across the Upper Mississippi River Valley. This weak front may skirt the northern extent of the sfc high pressure. Latest guidance still suggests that the front will stall over or just north of the CWA late Friday night into Saturday, supporting at least small chances of convective activity during this time, mainly for the northern portions of the CWA. Through the weekend and into early next week, a weakness in the upper level flow between the upper ridge over the swrn CONUS and the Bermuda high east of FL may allow a potential tropical system to sneak north into the Lower Mississippi Valley. While there is still considerable uncertainty as to how this system will develop and where it may track, it will need to be watched over the next few days to see if any moisture associated with this system can get into, at least, the southeastern portions of the CWA by the middle of next week. && .AVIATION... For the 00Z TAFs... 700 PM...Forecast concerns include... Isolated thunderstorms this evening...southeast of the terminals. Wind shift to northeast Thursday morning. Mvfr cigs Thursday morning. A weak cool front is moving across the area currently and isolated thunderstorms will be possible southeast of the terminals for the next few hours. Westerly winds will turn northwesterly this evening with gusts into the lower 20kt range possible through sunset. Winds will continue to turn northerly by daybreak and will become northeast Thursday morning. Confidence on timing is only medium and its possible that winds will shift northeast earlier than currently advertised in this forecast. Gusts into the mid/upper teen kt range will be possible Thursday afternoon diminishing Thursday evening. Much of the guidance is suggesting mvfr cigs will develop after sunrise across the area with cigs near 1kft across much of northwest IL. Followed these trends and introduced mvfr cigs with this forecast but confidence on specific heights is low. Cigs should begin to lift by late morning with scattering expected in the afternoon. cms && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...Beach Hazards Statement...INZ001-INZ002...2 PM Thursday to 4 AM Friday. LM...Small Craft Advisory...LMZ743-LMZ744-LMZ745...2 PM Thursday to 4 AM Friday. && $$ 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 Marquette MI
811 PM EDT Wed Jul 10 2019 .UPDATE... Issued at 322 PM EDT WED JUL 10 2019 Still a tricky forecast this afternoon. A few showers developed along what appears to be an enhanced Lake Michigan breeze boundary pushed all the way up to Lake Superior by prevailing southerlies. An additional light shower popped up near Ironwood in the last hour in the neighborhood of enhanced 925mb fgen. None of these have been able to sustain any strength to the updrafts as of yet. Now, after 19Z, a few cells are becoming more organized just north of the Pictured Rocks. The main event is still expected to get going after 4pm EDT, increasing in coverage and intensity into the early evening and then moving out east of Luce County by about 10pm. Coverage will likely be better over the northern tier of counties than further south owing to stronger forcing, and will still be scattered at best rather than widespread. In fact most CAMs are indicating better coverage over eastern Lake Superior than the UP. Mixing down of dry air has led to steep low level lapse rates over the central UP, but this has allowed ample dry air to mix down there and thus an instability minima exists over MQT, Iron, and Dickinson Counties. It does appear that the best deep layer shear will be a little out ahead of the forcing through this event, but may still maximize at around 40 kts. Thus, a rotating updraft is still not out of the question, but is not exactly likely. Low level shear is weak in a 0-1km sense, but picks up to 30-35 kts for 0-3km. With some south and even southeasterly component to the 5-10 knot sfc winds out in the east, still can`t completely rule out a brief spin up east of a Marquette to Iron Mountain line. More likely hazards will be isolated large hail and some gusty winds with any stronger cells that do develop. Some lingering isolated drizzle or light showers are likely to stick around through tonight over the north where onshore/upslope flow will keep the lower levels moist before drier air can fully filter in behind the front. Marine fog over Lake Superior will also stick around this evening, perhaps pushing south towards the shoreline ahead of the front, and then gradually dissipate as this drier air moves in. && .SHORT TERM...(This afternoon through Thursday evening) Issued at 1138 AM EDT WED JUL 10 2019 ...STRONG TO SEVERE THUNDERSTORMS POSSIBLE MAINLY FROM MARQUETTE AND DICKINSON COUNTY EASTWARD AFTER 4PM EDT... Lingering low clouds over Schoolcraft and Luce Counties this morning have exited, and skies across the Upper Peninsula have been partly cloudy through the day with only daytime cumulus. The warm front has already pushed through the region with even 15Z readings of 81/66 at IMT and 79/71 at MNM. At IMT, those dew points have already started to mix downwards thanks to relatively dry air aloft. Per RAP analysis, the sfc low was located north of Isle Royal late this morning and it is expected to pick up the pace northeastward this afternoon. The cold front, located out over the arrowhead of MN at 15Z, will continue it`s trek across the area relatively quickly through this evening. 12Z GRB sounding matched up pretty well with the NAM fcast, with a near sfc inversion and a number of smaller ones up the column. These should mix out by about 18Z. CAMs have trended later with convective initiation, and the expectation is for most of the activity to be centered along and east of a line from about Iron Mountain to Big Bay. West of there, some scattered showers and an isolated thunderstorm or two are possible, but better parameters for strong to severe storms will be to the east. HRRR seems to be underdoing both instability and shear in relation to most other CAMS and SREF members, and thus the depiction of model reflectivity is a bit more cellular than expected. A plume of 1500- 2000 J/kg SBCAPE over the east this afternoon seems likely, and isolated pockets of slightly higher values cannot be ruled out. This, in combination with 50 kts bulk shear per RAP analysis, will allow for the possibility of robust convection. East of Munising to Escanaba looks to be where the best chance for low level southerlies early on, with strong southwesterlies aloft, and thus rotating updrafts remain possible for at least the first couple hours before storms grow upscale into a more linear configuration. More likely hazards will be brief heavy downpours as well as the potential for large hail (supported by WBZ heights near 9-9.5 kft and at least some dry air aloft for entrainment) and gusty winds (supported by the aforementioned dry air and DCAPE values per RAP soundings near 1200 J/kg). Storms are expected to exit the region by about 03Z. .LONG TERM...(Thursday night through Wednesday) Issued at 220 PM EDT WED JUL 10 2019 Not to many changes in the extended with fluctuating temperatures, with highs in the 70s on cooler days and 80s on warmer days, through the end of the week and throughout the weekend a couple of cold fronts push across the area. Upper-level ridging is progged to build in next week and push over the eastern half of the CONUS, placing us under persistent warm air advection and the return of persistent above-normal heat. While we will remain on the northern periphery of the ridging, it still looks like we will get back into an active period of weather as shortwaves crests the upper-level ridge. While it is certainly too far out to talk specifics, we could be looking at decent chances for MCSs rolling across the region. Models have trended a bit cooler and breezier on Thursday behind the exiting cold front. Didn`t make too many changes to the forecast other then bumping up the sustained and gust wind fields. Given the onshore flow east of Marquette, it certainly looks like tomorrow we will see a moderate to high swim risk along the beaches of Lake Superior for Marquette and Alger County. Temperatures look borderline as they should be a bit cooler near the shoreline; however, with models also trending dry with clearing earlier in the morning hours near the shoreline a beach hazards statement may be required. Winds will relax overnight Thursday as high pressure moves overhead. This also will lead to a pleasant night with overnight lows dropping into the mid to upper 40s inland, and 50s near the Great Lakes. On Friday, shortwave energy tracking east across the Dakotas will traverses the Upper Great Lakes, pushing another cold front across the region. Ahead of this cold front, it will get warm and humid yet again, with daytime highs in the 80s, except downwind of Lake Michigan where 70s will prevail. With the main axis of deeper moisture and return flow shifting east across the area Friday afternoon, depending on how early morning convection plays out, medium-range models are showing the potential for thunderstorms that afternoon and evening. With increasing moisture throughout the day, the GFS and NAM show an axis of 1500-2000+ J/kg of SBCAPE. The instability coupled with boundary perpendicular deep-layer shear of 30-40 knots, is cause for concern for the potential for severe thunderstorms. Given the subtle nature of the shortwave, thinking any thunderstorm activity should be more isolated/scattered in nature, which would increased chances of updrafts maintaining better organization/strength. Given the environment in place, large hail and damaging winds look to be the main hazards. Cannot rule out a tornado if any boundaries develop locally; however, low-level shear and surfaces winds veering westerly are not favorable for tornadic activity. Much of the upcoming weekend looks nice as another area of high pressure drops south across the area. Saturday will be the coolest day of the weekend behind the departing cold front. However, Sunday the main area high pressure starts to shift southeast of the region and we will find ourselves back under warm/moisture return flow. As high pressure continues to push eastward and upper-level ridging builds across the central CONUS through the early/middle parts of next week, this will push us back into a hot and humid spell. As we remain on the northern-edge of the upper-level ridging Sunday through next week, this will put us in the potential zone for MCS activity. However, this far out there is still a lot of uncertainty in regards to where and when the best chances for precipitation and thunderstorms will be late weekend/next week. To make things more complicated in the extended, tropical activity well to our south will certainly have an impacted on the overall pattern and play a role in making next weeks forecast a bit more complicated until we get closer. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 809 PM EDT WED JUL 10 2019 Isolated showers are possible near KSAW through 03z. Otherwise, MVFR cigs are expected overnight as low level moisture moves in overnight behind a cold front moving through Upper Michigan. VFR conditions will return by mid to late Thursday morning as drier air setttles across the area. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 219 PM EDT WED JUL 10 2019 Areas of fog have been observed on the lake today over primarily locations 30+ miles north of Upper Michigan, which is expected to gradually dissipate this evening and tonight as a cold front brings a cooler, drier air mass to the region. Strong thunderstorms are possible across eastern Lake Superior late this afternoon and evening. Hail and strong winds are the primary threats. Winds have come down this afternoon over the lake, but the cold front coming across tonight will cause winds to increase out of the west and then northwest, gusting in the 20 to 25 knots range, with some gusts up to 30 knots across higher platforms. Winds will diminish tomorrow evening, but may reach up to 25 knots again on Friday from the west to northwest as another weak cold front passes across Lake Superior. After Friday, winds should remain below 20 knots. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ UPDATE...KCW SHORT TERM...KCW LONG TERM...Ritzman AVIATION...JLB MARINE...KCW
Area Forecast Discussion
National Weather Service Phoenix AZ
358 PM MST Wed Jul 10 2019 .UPDATE...Updated Aviation Discussion... && .SYNOPSIS... The Monsoon High will be the predominant weather feature through next week, resulting in a continuation of the above normal temperatures. Moisture will also steadily increase, resulting in a threat of isolated storms each afternoon through next week, particularly from Phoenix north and eastward. && .DISCUSSION... Streamline analysis clearly depicts anticyclonic flow across the Desert Southwest associated with the Monsoon High building northward through New Mexico. Further west, a vort max is evident across central Arizona, which is helping to transport richer moisture northward. Latest surface observations indicate that temperatures and dewpoints in particular are several degrees higher than they were this time yesterday. Meanwhile, temperatures in the mid-levels are relatively cool, owing to the presence of the vort max and corresponding inverted trough. PSR sounding climatology suggests this morning`s 500 mb temperature of -10 deg C is near the all-time record low. Mid-level lapse rates are consequently quite steep, which is supporting a CU field across the Mogollon Rim. Given the limited moisture, only isolated showers are likely across the higher terrain. Latest HRRR indicates any light showers that develop this afternoon will lift northward, with no impact across the lower deserts. Latest NAM-WRF simulated satellite imagery suggests that broken cloudiness will overspread the region Thursday and Friday as PWATs steadily climb above 1.0 inches. This will certainly affect insolation and the NBM MaxT has trended 1 to 2 degrees cooler than previous runs. Although the forecast high temperature for Phoenix is 111 degrees, the ECMWF and GEFS ensembles are exhibiting relatively high variability, suggesting that if there are enough breaks in the clouds, the temperature could potentially climb a few degrees higher. The persistent clouds will linger into Friday morning, resulting in well above normal temperatures overnight when people are anticipating a reprieve from the heat. Bottom line is that the Excessive Heat Warning will continue through Saturday evening for most lower desert locations. The cloudiness will also inhibit instability Thursday and hi-res CAMs suggest that only a sprinkle or perhaps an isolated shower will be possible. Less clouds are likely for Friday, resulting in somewhat more CAPE in the afternoon and an increased threat of showers and thunderstorms. Conditions will also be favorable for a dust storm south and east of Phoenix. && .PREVIOUS DISCUSSION... In addition to the continued heat Saturday, there will be a continued increase in the chances for convection over south-central Arizona. While PWAT and CAPE continue to climb and are elevated over the western deserts, low levels look to be too dry to support any significant storms and thus POPs out west will stay in single digits. We raised POPs a bit for south-central and have slight chances for storms south and east of Phoenix. Of course, dust storm potential will also climb over the deserts. For the rest of the forecast period, Sunday through Tuesday, we will remain in a somewhat low grade monsoon pattern; the upper high will remain near or a bit south of the 4 corners area keeping a general southerly steering flow in place and moisture will remain modest. CAPE values will also be modest with highest values east of the lower Colorado River Valley. Steering flow actually starts to turn more to the south/southwest by Tuesday further confining storms that develop to south-central Arizona and mainly high terrain locations east of Phoenix. With moisture still only at moderate levels we will see high temperatures remain elevated each day with hotter deserts running around 110 and just below heat warning thresholds. && .AVIATION...Updated at 2300 UTC South-Central Arizona including KPHX, KIWA, KSDL, and KDVT: Westerly winds will remain breezy at times through early evening, diminishing some after sunset but remaining out of the west through at least midnight. Winds at KPHX should stay out of the west through the overnight with only a brief period of easterly winds early Thu morning. Clouds will be increasing tonight, but generally above 15K feet. Some pockets of virga are also possible mostly south and southwest of the metro early Thursday morning. West winds Thu afternoon will again be gusty at times. Southeast California/Southwest Arizona including KIPL and KBLH: No aviation impacts through the TAF period with mostly clear skies. Winds will follow typical diurnal trends with speeds generally less than 10 kts. Periodic afternoon breeziness will occur at KBLH with gusts mostly around 15 kts. Aviation Discussion not updated for amended TAFs. && .FIRE WEATHER... Saturday through Wednesday: Above normal temperatures and humidity will persist through next week. Isolated storms will be possible each day, particularly across the higher terrain of Arizona. However, the chance for wetting rains will be somewhat lower. Winds will generally be light, except in the vicinity of thunderstorms. && .SPOTTER INFORMATION STATEMENT... Spotters should follow standard reporting procedures. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...Excessive Heat Warning from 10 AM Thursday to 8 PM MST Saturday for AZZ537-540-542>544-546-548-550-551-556. Excessive Heat Warning from 10 AM to 8 PM MST Friday for AZZ532- 534-536-538-539. CA...Excessive Heat Warning from 10 AM to 8 PM PDT Friday for CAZ565- 567. && $$ DISCUSSION...Hirsch PREVIOUS DISCUSSION...CB AVIATION...Kuhlman FIRE WEATHER...Hirsch
Area Forecast Discussion
National Weather Service Pueblo CO
555 PM MDT Wed Jul 10 2019 .UPDATE... Issued at 549 PM MDT Wed Jul 10 2019 Ran a quick update to bring in the latest observations and adjust precipitation chances for this evening. The latest high-res model solutions develop isolated activity over the Sangre de Cristo range through sunset, with more isolated activity developing over a pocket of higher instability over Baca County. Mozley && .SHORT TERM...(This evening through Thursday) Issued at 343 PM MDT Wed Jul 10 2019 Tonight and Tomorrow: Upper level high pressure system is currently centered over southwestern Colorado and northwestern New Mexico. Any isolated convection that developed over the mountains will dissipate by sundown as downslope flow stabilizes the atmosphere. The surface flow over the plains is from the southeast, which will advect some moisture originating from the Gulf of Mexico over the eastern plains. That moisture plume will be responsible for an increased chance at an isolated thunderstorm that may develops over the Wet Mountains this evening. The HRRR model trends are consistent in developing a thunderstorm over the Wet Mountains and for the storm to propagate along the theta-e ribbon south towards New Mexico. The GFS is in agreement in that outcome as well. The NAM has isolated thunderstorms along the main theta-e plume, but there is no organized convection. The European model has no convection during the overnight hours, whatsoever. The weather grids will have isolated POPs over the lower Arkansas River Valley and will have QPF. If the thunderstorm develops, it will be out of Pueblo`s CWA by morning. The higher dew points will increase the minimum temperature overnight over the plains. So expect low temperatures over the plains to be in the mid-to-upper 60s, the mountain valleys in the upper 40s to lower 50s, and the mountains in the upper 30s to low 40s. The upper level ridge remains over Colorado tomorrow, which will slowly bring Pacific based moisture towards the region. The added moisture combined with diurnal winds up the mountains will spark scattered (as compared to isolated the day before) thunderstorms over the mountains. PW values, though higher than the previous day, are still relatively low, which will put a limit on how liquid will fall and how strong the storms will be. The "La Junta low" will develop over the plains tomorrow afternoon, creating a moisture boundary east of La Junta. CAPE values east of the moisture boundary will be around 2500-3000 J/kg, but bulk shear values are less that 30 kts. The only lifting mechanism that seems to be around is the upslope flow towards the Palmer Divide. An isolated thunderstorm may develop along that boundary, but it is anticipated to be a pulse thunderstorm, meaning that the storm will be brief but may produce isolated gusts up to 60 mph and hail larger than quarters. .LONG TERM...(Thursday night through Wednesday) Issued at 343 PM MDT Wed Jul 10 2019 Recent forecast model soundings, PV analysis and computer simulations indicate that varying degrees of upper level ridging will impact southern Colorado during the balance of the longer term. In addition, projected increased atmospheric moisture in combination with occasional weak upper impulses and surface northerly surges will allow for elevated precipitation chances at times during the balance of the longer term. At this time, it appears that the highest potential for more widespread shower and thunderstorm coverage(including the potential for locally heavy storms, capable of producing localized flooding, including but not limited to recent burn scars) should be realized this weekend and possibly continue into next week(with the latest GFS solution signaling more aggressive storm activity than the recent EC solution). Overall, near to above seasonal mid-July maximum and minimum temperatures are anticipated over the majority of the CWA during the balance of the longer term with warmest conditions anticipated Thursday and Friday(with maximum temperatures challenging 100F over select southeastern Colorado plains locations) and then again by next Wednesday. Finally, generally low-grade gradient winds are projected during the balance of the longer term over southern Colorado. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 343 PM MDT Wed Jul 10 2019 VFR conditions are expected for KALS, KCOS, and KPUB throughout the forecast period. There is a chance for an isolated thunderstorms to develop over the Wet Mountains and travel in the vicinity of KPUB during the overnight hours. Scattered thunderstorms are anticipated over the higher elevations, so thunderstorms will be in the vicinity of all of the forecast points. If a thunderstorm does develop over KALS, KCOS, and KPUB, expect locally heavy rainfall which would lower visibility and erratic and gusty winds. && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...MOZLEY
Area Forecast Discussion
National Weather Service Blacksburg VA
905 PM EDT Wed Jul 10 2019 .SYNOPSIS... A cold front will approach from the west overnight into Friday. This front should push south of the Mid Atlantic by this weekend as high pressure builds overhead. Hot and humid weather should continue into early next week. && .NEAR TERM /THROUGH THURSDAY/... As of 900 PM EDT Wednesday... Isolated slow moving convection continuing in spots this evening, mainly north of Roanoke and across the southwest mountains into NC. This in association with lingering instability and a quick return in deeper moisture per high Pwats off evening soundings. Latest HRRR seems to have the best handle on current coverage with some isolated showers persisting into the overnight off residual outflow. Thus leaving in 20ish pops espcly mountains into the overnight after current showers fade, while boosting fog where heavier rain did occur earlier on. Lows to remain muggy given so much moisture around with eastern locations likely staying above 70 with mid/upper 60s west. Previous discussion as of 230 PM EDT Wednesday... Showers and thunderstorms will continue to slowly develop during the remainder of this afternoon. However, instability has only increased somewhat due to peristent cloud cover left over from a retreating cool wedge. The atmosphere should gradually destabilize with time, but weak steering currents will not allow much organization of any convection. DCAPE exceeds 1,000 J/kg due to notable dry air aloft in the model soundings. Thus, if any storms can obtain some vertical depth later this evening, there could be a threat of gusty winds. Precipitable water values near 1.50 inches also indicates some heavy rainfall may be possible in the stronger storms. Tonight should remain quite humid with dewpoints staying in the mid 60s to the lower 70s. Any convection from the evening should taper off before midnight. Patchy fog was included in the forecast along some river valleys for early Thursday morning, but most locations will probably witness just low clouds. The threat for heavy rainfall and severe will be more notable during tomorrow afternoon with high temperatures expected to be a few degrees warmer compared to today. CAPE during Thursday will likely reach 1,500-2,000 J/kg, and an approaching cold front from the Ohio River Valley should provide more synoptic lift to increase the coverage and organization of the storms. Damaging winds and localized flooding from heavy rain will be the main threats. However, confidence is too low to provide more refined location details other than mentioning that the greatest severe threat appears to be north of Route 460. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/... As of 215 PM EDT Wednesday... There will be lingering convection as we head into Thursday evening with front slowing down with another upper vort moving across the central Appalachians. The front will be east of us by Friday morning with lingering upslope showers possible. The front will linger south of the VA/NC border into Friday, while another area of shortwave energy passes across. The models showing at least fair 40-50 percent chance of showers/storms Friday across our southern area, with high pressure keeping the northeast CWA dry. Drier air should push across the region by Saturday, although the front stays situated from the Gulf Coast stats into eastern NC while TC Barry enters the lower MS Valley. May see just enough buckling in the flow and moisture advection across the mountains to keep chance pops in Saturday in the southwest. Temps will stay elevated despite front as not much change in low level thicknesses though RH drops off Saturday. Confidence is medium on how far south the front goes and chance of storms especially Saturday. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... As of 130 PM EDT Wednesday... The forecast will center on the track of what is expected to be Tropical Storm, possibly Hurricane Barry. Numerous models are close in general direction of this storm, with it situated across the mid- lower MS Valley next week, while weakening. Meanwhile, 500 trough is situated over the northeast U.S. with broad ridge over the southeast. Some differences by day 7-Wed with GFS allowing for Barry to picked up by the westerlies and shifted east toward KY, while the Ecmwf keeps the remnants further west across mid MS valley with a stronger ridge in the southeast. Ensembles showing a blend of these two. For our area, will see less threat of storms although a back door front edges close to the area Sunday-Monday, models have backed off on rain chances, mainly diurnal widely scattered threat. Will remain very warm to hot and humid and mainly dry through the period. Confidence is medium on track of Barry and impact on our area. && .AVIATION /01Z THURSDAY THROUGH MONDAY/... As of 645 PM EDT Wednesday... Conditions should remain mostly VFR through this evening, but the potential for MVFR exists from lingering cloud cover and a chance for showers and thunderstorms mainly along/west of the Blue Ridge. However given very isolated coverage attm, will only keep a VCTS mention around KLWB/KBCB and KROA into this evening. Winds should stay light from the south to southwest this evening into the overnight. Tonight a combination of damp ground and a humid atmosphere will make low clouds and/or patchy fog a good possibility. The best chance for IFR resides at KLWB, while MVFR could occur at other valley locations but likely wont include elsewhere at this point at other sites. KROA has the highest confidence of staying VFR through the night. Conditions should recover to VFR for all sites during Thursday, but showers and thunderstorms could impact aviation concerns during the afternoon as a cold front approaches from the northwest. Appears could see convection develop in the KBLF-KLWB corridor by midday and elsewhere during the afternoon. Models also suggest some lighter showers during the morning across the mountains so something to watch. Therefore given the high probability of all sites seeing showers/storms have included a prevailing shower and/or VCTS mention Thursday afternoon with at least brief MVFR or worse possible into the early evening. .Extended Aviation Discussion... A cold front should cross overhead during Thursday night. MVFR conditions may accompany the showers and thunderstorms before the convection decreases toward early Friday morning. Some showers could linger into Friday before drier air arrives by Friday night. High pressure should arrive and maintain control to provide overall VFR through the weekend into Monday. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...PW NEAR TERM...JH/PW SHORT TERM...WP LONG TERM...WP AVIATION...JH/PW
Area Forecast Discussion...UPDATED
National Weather Service Shreveport LA
1028 PM CDT Wed Jul 10 2019 .UPDATE... The strongest convection has exited the forecast area to the southwest into Central Texas. However, additional showers and thunderstorms are developing across Northern and Central Louisiana along an outflow boundary that is moving south and southeast across the area. This new convection will likely persist through the overnight hours, but intensity and coverage should gradually diminish. PoPs were updated to account for this. The storms helped to cool several locations below the forecast low temperatures, particularly along and north of Interstate 30. Temperatures will likely hold steady, possibly even warm a degree or two in these areas through the overnight hours. Updated text products will be sent shortly. CN && .PREV DISCUSSION... /issued 659 PM CDT Wed Jul 10 2019/ AVIATION... For the 11/00z TAFs, a line of strong to severe convection will progress southward across the area early in the period. These storms should very slowly weaken by 11/06z. Most of the TAF sites will be affected, but the latest model guidance suggests the convection will greatly diminish before reaching KLFK. Otherwise, VFR conditions should prevail. More scattered convection is possible after 11/16z, mainly across Louisiana and East Texas south of Interstate 20. CN PREV DISCUSSION... /issued 417 PM CDT Wed Jul 10 2019/ SHORT TERM... This evening, the HRRR indicates that isolated thunderstorms will continue to develop in an environment with strong instability (SBCAPE 3000-5000 J/kg) and abundant moisture (PWATs near 2 inches) this afternoon into the evening. As the weak cold front approaches from the north, lingering convection and outflow from upstream convection will help increase chances of showers and thunderstorms this evening for locations along the I-20 corridor and northward. Showers and thunderstorms will mostly diminish tonight with chances decreasing to a slight chance overnight. Remnant clouds from earlier thunderstorms along with cirrus continuing to filter in ahead of the tropical system should keep skies partly to mostly cloudy. The chance of showers and thunderstorms will increase again tomorrow afternoon with daytime heating. With the lingering frontal boundary there is the potential for locally heavy rainfall thunderstorms. For temps, another oppressively hot afternoon is expected tomorrow with highs in the mid 90s and heat indices warming into the 105 to 110 degree range. With this in mind, a Heat Advisory remains in place for everywhere except Red River and McCurtain counties through tomorrow. Tonight and tomorrow night, lows will be in the mid to upper 70s. /04-Woodrum/ LONG TERM... The National Hurricane Center commenced advisories on Potential Tropical Cyclone Two at 10 am CDT this Wednesday morning. For information concerning this developing system, please refer to the discussions and graphics from the NHC. For Friday, with the forecast, strengthening, tropical system in the northern Gulf of Mexico, SCT TSTMS begin to affect central LA and deep E TX as the outer bands of the tropical system spread N into LA. The tropical system is then forecast by NHC to slowly move NW through WRN LA, and center over extreme NW LA by Monday morning shortly after daybreak. This scenario results in unsettled weather into at least the middle of next week with SCT to numerous showers and TSTMS. A deep tropical moisture airmass would of course result in the potential for flash flooding issues. The main threat of heavy rainfall will be over the eastern semicircle of the circulation. Fortunately, this July commenced with typical very warm conditions with only scanty rainfall. This trend allowed antecedent soil moisture conditions to dry and area rivers, bayous, and lakes to recede after our rather wet winter and springtime of 2019. In any case, our dryer than normal spell that began this July will end this weekend into the middle of next week. As for winds with this system, the NHC currently forecasts a hurricane to be inland in SW LA during Sunday morning just after daybreak. By Monday morning, NHC then forecasts a tropical depression over extreme NA LA. Current thinking is that tropical storm force winds during Sunday afternoon may affect our southern sections of our southern parishes: Natchitoches, Grant LaSalle, and possibly Sabine. Have blended our SFC winds for this weekend with the wind forecasts from LCH. /VIII/. && .PRELIMINARY POINT TEMPS/POPS... SHV 76 94 76 92 / 40 30 10 30 MLU 78 94 76 92 / 40 30 30 40 DEQ 73 94 71 92 / 50 20 0 0 TXK 73 92 73 90 / 60 20 10 10 ELD 76 94 74 90 / 40 20 10 30 TYR 73 93 74 92 / 40 20 10 10 GGG 76 94 75 92 / 40 30 10 20 LFK 77 94 77 93 / 20 40 20 30 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...Heat Advisory until 7 PM CDT Thursday for ARZ070>073. LA...Heat Advisory until 7 PM CDT Thursday for LAZ001>006-010>014- 017>022. OK...None. TX...Heat Advisory until 7 PM CDT Thursday for TXZ097-108>112-124>126- 136>138-149>153-165>167. && $$ 09/20