Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/21/18

Area Forecast Discussion
National Weather Service Binghamton NY
935 PM EDT Mon Aug 20 2018 .SYNOPSIS... Low pressure will move west of the area Tuesday into Wednesday bringing showers and isolated thunderstorms to the area late Tuesday and early Wednesday. High pressure with drier air will move in for the end of the week. && .NEAR TERM /THROUGH TUESDAY/... With the late evening update we made some adjustments to the sky cover based on ongoing conditions. Also temperatures have fallen off fairly quickly as well the last couple of hours and were adjusted slightly with both evening updates. However, the forecast in large part remains on track with the previous discussion below. Low over NE Indiana Tuesday morning races northeast as it deepens, to southern Quebec by Wednesday morning. Ahead of the system, Atlantic moisture with marine layer is drawn north into the area bringing low level moisture and low clouds later tonight into Tuesday. Upper level warm front pushes through late Tuesday and should generate some light showers. Models have backed off on the heavier rains forecast as they weaken the convection as it runs east. Part is due to the lack of any low level instability, and mid level dry air. Behind that, a cold front races east in the early morning hours Wednesday. Again the models have backed off on the QPF amounts with only marginal instability and the upper jet support passing well to the north and west. With the late evening update, we also delayed the onset of precipitation into the morning given the latest HRRR, RAP and RGEM now hold off any rain chances getting into the Finger Lakes till late morning. && .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY/... 3 am update... A cold front will be racing east of our region with a broad mid- level trough over the region on Wednesday. Modeled soundings do show some steeping of the low-level lapse rates with the northwest flow pattern also contributing a little bit of moisture as well. These factors may lead to a few additional spotty showers throughout the day. The main story will be the northwest winds behind the front with the potential for a few northwest wind gusts around 20 mph in the afternoon hours. With a mostly cloudy and northwest flow, highs will struggle to get well into the 70`s. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... Wednesday night through Friday night: High pressure from Canada will build into the region Wednesday night and Thursday resulting in a period of much needed dry and refreshing weather across the region. Northwest winds will gradually decrease as the high builds in. Highs should be in the 70`s with lows in the 50`s. With favorable conditions for radiational cooling with the high overhead Friday morning a few spots may actually fall into the upper 40`s for morning lows. Some patchy fog is possible Friday morning as well. High pressure slowly starts to move out Saturday, with one last dry day expected. Morning lows are expected to fall into the upper 50s/low 60s and highs generally reach in the mid to upper 70s and low 80s. Saturday night, our area starts to get into the return flow behind a surface high, and a surface low and associated mid-level trough move through Ontario and Quebec. This results in increasing clouds and chances for showers Saturday night. The Euro continues to be the outlier, bringing this feature through more quickly with showers beginning as early as Saturday afternoon. For Sunday and Monday, warmer and more moist air works in with S/SW flow near the surface. Weak waves continue to pass through, with mainly westerly flow aloft, and lingering chances for showers both days. Thunder will be possible during the afternoon and evening hours owing to better instability. With PWATs in the 1-1.5in. range, a heavy downpour is not out of the question - and with little shear to speak of, slow- moving cells could be a concern. However, there is little forcing apart from any weak shortwaves, so this isn`t looking like a widespread heavy rain event. Lows generally will be in the low/mid 60s Sunday morning, with highs likely in the upper 70s and low 80s. Continued warming Monday should bring in lows in the mid/upper 60s and highs in the low/mid 80s as dewpoints increase into the 60s and low 70s. && .AVIATION /02Z TUESDAY THROUGH SATURDAY/... A southeast flow overnight will bring low level moisture into most of the terminals. For all terminals but KSYR, ceilings will lower into the MVFR/Alternate Required category between 03Z-09Z. The restricted ceilings will remain through the morning hours then a warm front during the afternoon will produce MVFR/Alternate Required showers at all terminals. E/SE winds overnight at 5-8 knots. S/SE winds developing by late morning Tuesday at 8-12 knots with gusts around 18 knots. Outlook... Tuesday night into Wednesday...Restrictions probable in showers and thunderstorms. Wednesday afternoon through Saturday...VFR. Early morning fog possible, especially KELM. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...None. NY...None. && $$ SYNOPSIS...DGM NEAR TERM...DGM/MWG SHORT TERM...MWG LONG TERM...HLC/MWG AVIATION...RRM
Area Forecast Discussion
National Weather Service Bismarck ND
957 PM CDT Mon Aug 20 2018 .UPDATE... Issued at 952 PM CDT Mon Aug 20 2018 Decreased lows into the lower 40s north of US Highway 2 where skies will clear late tonight. Also increased PoPs across the southwest and south central for the overnight per the 00 UTC CAM suite and upstream radar trends across Montana. UPDATE Issued at 637 PM CDT Mon Aug 20 2018 Little change with this forecast update. Expect rain showers to spread into southwest North Dakota between 02-04 UTC from southeast Montana with a series of impulses that will phase overnight with a northern stream shortwave. && .SHORT TERM...(This evening through Tuesday) Issued at 222 PM CDT Mon Aug 20 2018 The return of smoky skies and continued cool conditions highlights the short term forecast. Regarding the smoke: The vertically integrated smoke product, from the latest iterations of the RAP and ESRL HRRR Smoke models, suggest that smoke will continue to be on the increase from the west today, and spread east through tonight, likely lasting until at least daybreak Tuesday when the model forecasts some clearing of smoke from north to south. Today North Dakota was between 3 upper level low pressure systems: the first an upper level low over Hudson Bay, keeping broad cyclonic flow across south central Canada and Northern North Dakota; the second a closed low over the mid-Mississippi Valley; and the third upper level trough over the western/central US Rockies. Upper level impulses emerging from the western/central US Rockies trough were moving east across Montana and Wyoming today. This was associated with the shower activity seen on regional radars over MT/WY. Tonight a shortwave in the northwest flow aloft over south central Canada will track southeast across North Dakota. As this occurs, upper level impulses emerging from the western/central US Rockies trough continue moving east across Wyoming and South Dakota, clipping far southern North Dakota. The short term high res and global models agree putting scattered showers and thunderstorms across southwestern North Dakota tonight, moving southeast out of our area during the morning hours on Tuesday. Meanwhile at the surface: A large cool and dry high pressure system was centered over Alberta and Saskatchewan, with a narrow axis extending south across the western Dakotas and eastern MT/WY. Clear skies, light winds, and dry air combined to bring low temperatures ranging from 35F to the mid 40s across most of western and central North Dakota. Tonight the high pressure system is forecast to move southeast into eastern Montana and the Dakotas. Increasing clouds are forecast from west to east tonight, especially across the southern counties, associated with the upper level impulses and aforementioned chances of showers. Thus expecting widespread lows in the 40s again across western and central North Dakota, with some upper 30s possible across portions of the north under clearing skies. Slightly warmer Tuesday, with highs mainly in the 70s. .LONG TERM...(Tuesday night through Monday) Issued at 222 PM CDT Mon Aug 20 2018 The west coast trough begins to close off and meander slowly east Tuesday night and Wednesday, keeping a weak upper level ridge over our area. The large surface high pressure drifts southeastward, with return southerly flow becoming established over our area on Wednesday. This will allow a gradual warmup through the week, with high temperatures as high as 80 by Thursday. Thursday: The upper level Rockies closed low will finally make its way to the northern plains by Thursday, bringing chances for showers and thunderstorms across the area by the afternoon hours. Decent instability will likely be available, with moderate 0-6km shear up to 30 knots possible. At this time the Storm Prediction Center is targeting eastern SD/NE for possible severe storms, but some strong storms over the eastern half of North Dakota cannot be ruled out Thursday afternoon and evening. After the upper low kicks out of the region on Friday, the pattern looks to become a bit more progressive, with models in agreement of a fast zonal flow transition, leading to a deepening trough across the western US by the end of the weekend. Periodic chances of showers and thunderstorms will be possible across the region over the weekend, but the global models do not seem to have a solid handle of the fine scale details at the moment. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 952 PM CDT Mon Aug 20 2018 Rain will continue to spread across southwest and south central North Dakota through the night, decreasing after 09 UTC. A few embedded MVFR visibilities are possible within the heavier rain showers. KDIK is the most likely terminal to be impacted. KBIS will be on the northern fringe of the rain showers. Otherwise, VFR conditions are forecast for the 00 UTC TAF cycle across western and central North Dakota with surface high pressure. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...PA SHORT TERM...JV LONG TERM...JV AVIATION...PA
Area Forecast Discussion
National Weather Service Denver/Boulder CO
811 PM MDT Mon Aug 20 2018 .UPDATE... Issued at 757 PM MDT Mon Aug 20 2018 Smoke continues along the front range and actually has gotten somewhat worse this evening. latest HRRR Smoke Model continues to show this smoke lingering overnight but should see improvement by Tue morning. As far as pcpn there is quite a bit of activity over Utah this evening which appears to be associated with an upper level jet. This activity will affect nrn areas of the higher terrain after midnight and across lower elevations mainly near the CO-WY towards sunrise. && .SHORT TERM...(This evening through Tuesday) Issued at 252 PM MDT Mon Aug 20 2018 Smoke remained across most of the plains this afternoon, with the most concentrated smoke along the I-25 Corridor where the light easterly flow has banked it up against the Front Range. There has been some improvement late this afternoon with daytime heating and mixing. Higher up, including the foothills above about 7500 feet and across the mountains, the smoke has mixed sufficiently and is relatively thin as a more westerly component takes hold. We`ll still see some smoke/haze around through the night in the lower elevations, but we do expect some improvement by Tuesday morning and especially Tuesday afternoon when more mixing occurs and we get a few showers/storms pushing east across the forecast area. With regard to the precipitation threat, we do expect that to increase across the mountains by midnight and the northern border area thereafter tonight. Those showers will be driven by a passing speed max to our north and mid level moisture advection as noted in the specific humidity progs. There may be an isolated storm or two, and can`t rule out a couple showers/sprinkles on the plains stretching as far south as Denver before daybreak Tuesday. Overall chances for any measurable precipitation appear best over the high country. On Tuesday, a weak cold front will back across the area by early morning with a light upslope component developing. The airmass will become more moist and will destabilize during the course of the afternoon. CAPES are limited to less than a couple hundred J/kg in all but the mountains and Palmer Divide, but there should be enough lift and destabilization to support at least scattered storm development across the high country by early afternoon, with these storms also spreading east across the plains through the mid/late afternoon hours. Have dropped temps a couple degrees for the expected upslope easterly flow behind the front and more clouds than sun tomorrow. .LONG TERM...(Tuesday night through Monday) Issued at 252 PM MDT Mon Aug 20 2018 For Tuesday night into Wednesday the upper ridge will be over NM and TX with SW flow over the state. Models show a disturbance moving through the flow that will bring showers and thunderstorms Tuesday evening into early Wednesday. With the high pressure to the SW and the trough extending into northern CA this will help funnel additional moisture into the Great Basin and Colorado. PW values will be upwards of 1.3 inches by late Tuesday. There will be enough forcing to allow showers to continue into the early morning hours on Wednesday. Best convection, even in the later hours will continue to be closer to the mountains and foothills with more stable atm over the East. Showers will still be able to move over in the evening hours dropping moderate to heavy rain. Conditions will be cloudy Wednesday with cooler temperatures. At this time highs are only projected to get into the mid 70s. Another shortwave is projected to move through late Wednesday with once again having the best instability closer to the mountains and Palmer divide but still not impressive. Conditions over the far eastern plains look to be more stable Wednesday afternoon and evening. Convection will be more over the higher terrain with some storms possible over the Palmer Divide. these storms will be capable of heavy rain, gusty winds and small hail. Temperatures will rebound Thursday into the 80s with 60s in the mountains. The upper level trough will push in Wyoming and just brushing portions of Northern CO. Storms will form over the higher terrain Thursday afternoon with isolated chances over the plains. For Friday and into the weekend the ridge will push North bringing clearing skies and stable conditions Friday with highs reaching into the lower 90s. Saturday, another shortwave will push through with a surface low over the plains. This will bring scattered storms to the higher terrain and help to keep storms at bay until later in the day Saturday over the plains when the atm is able to destabilize. Vort maxes will continue to push through the SW flow as the upper ridge lingers over the southern CONUS bringing increased chances of showers and thunderstorms in the extended. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 757 PM MDT Mon Aug 20 2018 Smoke will continue this evening with visibilities in the 3 to 5 mile range thru midnight at least. It could even linger much of the night but should see gradual improvement towards sunrise. Winds were easterly early this evening but should gradually become more southerly by midnight. Late tonight winds will become light northwest. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...RPK SHORT TERM...Barjenbruch LONG TERM...Bowen AVIATION...RPK
Area Forecast Discussion
National Weather Service Quad Cities IA IL
659 PM CDT Mon Aug 20 2018 ...00z AVIATION UPDATE... .SYNOPSIS... Issued at 215 PM CDT Mon Aug 20 2018 As of 200 PM: A seasonably strong upper level low was located along the Iowa and Missouri border to the south of Des Moines. Bands of scattered showers and isolated thunderstorms were spiraling around the low and affecting parts of eastern Iowa and northwestern Illinois. Instability per the SPC Mesoanalysis has increased to 1000-1500 J/kg of MLCAPE, and with high PWATs near 1.7 inches, the atmosphere is supportive of localized heavy downpours. Across the forecast area, temperatures were in the mid 70s on average, and it was very humid with dewpoints near 70 F. && .SHORT TERM...(This Evening through Tuesday) ISSUED AT 215 PM CDT Mon Aug 20 2018 This Afternoon through Tonight Scattered showers and thunderstorms will continue through this evening. The main impact will be the brief heavy downpours. Monitoring satellite trends through the day, a brief window of clearing is most probably over the eastern and northeast sections of the CWA. Due to moderate low-level shear with 0-1 km values between 15-20 kts, and low LCLs and LFCs, isolated severe storms are possible. The Storm Prediction Center has outlined areas mainly along and north of I-80 for a marginal severe weather threat. If we were to get a few severe storms, the primary risks would be strong wind gusts and brief spin-up tornadoes. Latest HRRR model runs develop the strongest storms over the far east and in the northeast CWA, where there are more significant breaks in the cloud cover. We`ll have to continue to monitor conditions and radar trends through the evening. Additional rainfall will vary considerably across the forecast area, but because of the slow storm motion and high PWATs, isolated locations north of I-80 could pick up another 1-2 inches before it winds down early tonight. Tuesday After residual showers in the morning, dry weather and high pressure return for the afternoon along with seasonable temperatures. Uttech .LONG TERM...(Tuesday Night through Monday) ISSUED AT 215 PM CDT Mon Aug 20 2018 Wednesday and Thursday The high pressure system that begins to move in Tuesday will linger over the Midwest through Thursday. Expect highs in the 70s to near 80F and lows in the 50s. The cool overnight temperatures may lead to shallow fog formation in favored low-lying areas, but did not include fog in the forecast yet. Uttech Friday On Models bring a shortwave through Iowa and Illinois late in the week. The model blend has increased rain chances into the 50-70% range, which would come in the form of scattered showers and isolated thunderstorms. This is not a strong system, so the threat for widespread significant rainfall is low. Hot and humid conditions are likely by next weekend as the mid- level flow becomes southwesterly and forecast 850mb temperatures eclipse 20 C. The model blend has our area in the mid 80s to near 90 F with dewpoints near 70 F -- summer will be in full force heading into the final week of August. There is also a chance for thunderstorms Sunday and Sunday night with a potential shortwave tracking along an instability gradient. Confidence on the details is low this far out. Uttech && .AVIATION...(For the 00Z TAFS through 00Z Tuesday Evening) ISSUED AT 647 PM CDT Mon Aug 20 2018 Showers and a few storms will continue this evening with greatest coverage over northeast Iowa into northwest Illinois possibly impacting CID and DBQ, with more spotty coverage elsewhere. Overnight expect some spotty showers to linger with passage of upper level trough. Cooler and moist ground will aid in lower clouds with MVFR to pockets of IFR CIGs tonight into Tuesday. Winds will turn gusty from north at 10-20+ kts on Tuesday advecting in drier air, which should eventually lift any CIGs into VFR by afternoon. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ SYNOPSIS...Uttech SHORT TERM...Uttech LONG TERM...Uttech AVIATION...McClure
National Weather Service Eureka CA
256 PM PDT Mon Aug 20 2018 .SYNOPSIS...Hot and dry weather Monday afternoon will transition to cooler conditions by midweek. Otherwise, smoke will persist across most of the area through the rest of the week. && .DISCUSSION...Tomorrow marks the transition to a cooler, more seasonable pattern as an upper-level trough moves across the area. High temperatures are expected to be in the mid 80s to mid 90s across the interior with 60s occurring along the coast. In addition, brisk northerly winds will continue to promote upwelling and boundary layer stability, which will maintain stratus along the coast. Current visible satellite imagery shows smoke drifting south from wildfires in British Columbia, Washington, and Oregon. Recent HRRR guidance suggests this smoke will enter our area tonight. Thus, have introduced smoke into the forecast across the northern waters and most of Del Norte county. This area of smoke is forecast to continue drifting south across the remainder of the CWA through Tuesday. Another upper-level trough is forecast to the western U.S. late this weekend into early next week. Slightly cooler temperatures are expected across the interior with this trough, and model guidance is also hinting at a slight chance of rain. && .AVIATION...An extensive field of marine stratus continued to cover North Coast areas, adjacent river valleys and hills into the afternoon. The layer appeared to be slightly deeper today with bases as low as 200-300 feet. An early afternoon PIREP reported tops 1600 feet at CEC. A 1:00 PM VIS SAT picture showed plenty of cloud erosion. However, low CIGS remained persistent even as bases at ACV had lifted a little bit. Therefore, mid-late afternoon improvement to VFR conditions still on track. Stratus will most likely redevelop by mid to late evening with IFR conditions expected to last through the morning hours on Tuesday at both KCEC and KACV. Smoke from nearby wild fires have somewhat impacted KUKI since late morning as UKI`s VIS dipped down into MVFR and may briefly lower to IFR. It is also possible that smoke obscuration could lower CIGS down to MVFR. /TA && .MARINE...The brisk northerly winds and steep seas will continue to gradually subside across the waters as we go through the afternoon and evening. Light to moderate southerly winds will develop along the Mendocino coast by Tuesday morning and across the rest of the waters by Wednesday morning as a broad low pressure center moves offshore. North winds and steep wind waves will increase Thu through Fri. /WCI && .FIRE WEATHER...Gusty offshore flow is expected tonight across interior Del Norte county, with gusts to 30 mph possible across ridge tops. && .EKA WATCHES/WARNINGS/ADVISORIES... CA...None. NORTHWEST CALIFORNIA COASTAL WATERS...Small Craft Advisory until 9 PM PDT this evening for PZZ470-475. Small Craft Advisory until 3 PM PDT this afternoon for PZZ455. && $$ Visit us at Follow us on Facebook and Twitter at: For forecast zone information see the forecast zone map online:
Area Forecast Discussion...UPDATED
National Weather Service Grand Forks ND
950 PM CDT Mon Aug 20 2018 .UPDATE... Issued at 950 PM CDT Mon Aug 20 2018 Weak radar returns over central ND into the Devils Lake basin are mainly mid level clouds and are not expected to reach the ground with dry lower levels and a 15 to 20 degree dew point depression. UPDATE Issued at 713 PM CDT Mon Aug 20 2018 No significant changes needed in the ongoing short term forecast. A mild evening with fair skies and decreasing winds is ahead. && .SHORT TERM...(This evening through Tuesday) Issued at 303 PM CDT Mon Aug 20 2018 Expect generally fair skies and a light northerly flow to persist into the evening... with winds diminishing after nightfall. and overnight periods. Overnight low temperatures should settle into the upper 40s near the CanAm border and lower 50s near the South Dakota border. Meanwhile...upper level winds will be approaching from the west and bringing a fresh batch of smokey air into and across the area overnight... with the Canadian and HRRR smoke models keeping most of that particulate suspended aloft overnight and pushing out of the area early on Tuesday. We will monitor those conditions along with the ND Dept. of Health and MN PCA and update Air Quality bulletins through the day as needed. Otherwise...the current seasonably cool, dry, and fairly clean near surface airmass should stay with us into Tuesday... with light northwest boundary layer winds increasing by midday. High temperatures are expected to rise into the lower to middle 70s across the area. .LONG TERM...(Tuesday night through Monday) Issued at 303 PM CDT Mon Aug 20 2018 Tuesday night into Wednesday night mid-level ridging will continue to build into the Northern Plains while northwest flow shifts east towards northern Minnesota and the Great Lakes Region. Quiet weather is expected through this period as temperatures gradually warm into the lower 80s alongside mostly dry conditions. By Thursday, an upper-level trough and corresponding mid-level closed circulation will approach from the west bringing out next chance for precipitation in the area. In general, model guidance continues to favor a stronger precipitation signal in the southern Red River Valley while more forecast uncertainty persists for areas further north. As far as the severe potential, deep layer shear still appears to be on the weak end, however modest instability may have the potential to support a few stronger updrafts. The more pressing focus will be on higher precipitable water values on the order of 1 to 1.5 inches that may bring concerns for localized heavy rain. By Saturday into late Sunday, a secondary frontal passage will bring additional potential for rain for the area, however model consistency continues to place the bulk of the precipitation north of the international border. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 713 PM CDT Mon Aug 20 2018 VFR conditions are expected throughout the TAF period. North winds will weaken diurnally this evening, turning to the northwest and increasing again Tuesday morning. Mid level clouds will build in from western ND this evening, developing ceilings but remaining VFR. Smoke from Canadian wildfires streaming overhead may cause impacts through tonight and early Tuesday but is expected to have little to no impact at the surface for eastern ND and northwest MN. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. && $$ UPDATE...BP SHORT TERM...Gust LONG TERM...Lee/Honor AVIATION...BP
Area Forecast Discussion
National Weather Service Grand Junction CO
549 PM MDT Mon Aug 20 2018 .SHORT TERM...(Tonight through Tuesday night) Issued at 302 PM MDT Mon Aug 20 2018 As mentioned in the previous discussion, a shift in the pattern will bring a surge of subtropical moisture to the area. Specifically, a mid-level low over the Pacific Northwest will cause the quasi-permanent mid-level high to shift eastward tonight allowing moisture to move northeastward from the Mexican Plateau. Some of this moisture arrives later in the day, and when combined with a disturbance moving along the northern UT&CO/WY border will generate and sustain showers and embedded thunderstorms through the night, mainly north of the I-70 corridor. In addition, experimental HRRR smoke model suggests that smoke over the area will decrease later tonight. Moisture levels will continue to rise on Tuesday as the mid-level high retreats farther east, recentering over the southern Plains by midday. In response, precipitable water (PW) levels are expected to rise to near 1.25 inches in the Four Corners region to 0.85 to 1 inch elsewhere. Divergence associated with the jet just north of the forecast area and possibly a weak disturbance in the southwesterly flow is projected to generate numerous showers and thunderstorms over the higher terrain. That said, clouds should fill in early in the day limiting warming thereby inhibiting storm strength, and the area could see more quasi-stratiform rain. With moisture levels near an inch PW, cannot rule out localized heavy rain, but don`t believe threat rises to the level warranting a Flash Flood Watch. Shower/thunderstorm activity is expected to linger Tuesday night as weak upper level lift works on deep, lingering subtropical moisture. Temperatures will be relatively mild Tuesday night as moisture and clouds limit the escape of long wave radiation. .LONG TERM...(Wednesday through Monday) Issued at 302 PM MDT Mon Aug 20 2018 Monsoon moisture will continue to feed scattered to numerous showers and thunderstorms Wednesday. However, the mid-level low over the Pacific Northwest pushes eastward Wednesday night into Thursday ushering drier air into the area in its wake Thursday afternoon. Concurrently, the high over the southern Plains spreads back to the west disrupting the influx of subtropical moisture from the Mexican Plateau. As a result, the region will revert back diurnally driven showers and thunderstorms over the mountains each afternoon and evening with the southern mountains favored. Temperatures during the latter part of the week into this weekend will be close to seasonal norms. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 548 PM MDT Mon Aug 20 2018 Scattered showers are producing gusty winds at the KCNY, KVEL, and northern Colorado TAF sites this evening, and will continue to linger over the next few hours. A surge of moisture from the southwest tomorrow afternoon will lower CIGs and bring the threat of showers and thunderstorms back to the region. The hazy, smoky conditions will begin to lift as southwesterly flow takes over. VFR conditions will last through the period at all TAF sites. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && $$ SHORT TERM...NL LONG TERM...NL AVIATION...MMS/JPF
Area Forecast Discussion
National Weather Service Grand Rapids MI
958 PM EDT Mon Aug 20 2018 LATEST UPDATE... Update .SYNOPSIS... Issued at 237 PM EDT Mon Aug 20 2018 Showers and a few thunderstorms will move over the area this evening as a system approaches the area. Severe weather is not likely, however some localized gusty winds or a brief isolated weak tornado is possible south of a line from South Haven to Kalamazoo. Showers and a few storms will gradually taper off on Tuesday into Tuesday night. Drier and cooler weather will be found behind the system on Wednesday. Temperatures will warm back up again this weekend and could approach 90 degrees. There will be a chance of rain, although most of the time it will be dry. && .UPDATE... Issued at 958 PM EDT Mon Aug 20 2018 Although we have remained mostly rain free this evening due to dry air fending off incoming showers, the latest short term guidance continues to produce widespread 0.5 to 1 inch of rain later tonight and Tuesday. PWATs are progged to rise to around 1.75 inches from south to north as the system lifts northeast, so look for showers and sct`d tstms to fill in after midnight once the upper low/trough gets closer. Will have only low chance pops through midnight, then rising to 70 pct or more after midnight. Latest RAP guidance has MLCapes near 1000 J/KG making it up to the I-94 corridor after midnight, along with 0-3KM shear around 25 kts. That still points to a very low chance of a brief/weak spin-up, but the loss of any diurnal updraft contribution will make it difficult. SPC has removed our area from the MRGL risk. && .SHORT TERM...(This evening through Wednesday night) Issued at 237 PM EDT Mon Aug 20 2018 Our main concern in the short term is on convection trends through Tuesday, and any severe weather chances. Most of the area should not see severe weather, although the chance is not zero across the far SW corner of the area. Initial line of showers and storms trying to make their way into the area this afternoon are having a tough time advancing too far north and east initially. This is due to the dry air in place below about 20k ft. We do expect the better support and moisture with the front to bring pcpn in through mid-evening. As mentioned above, most of the area should not see severe weather tonight with the warm sector staying just south of the area and instability being of the elevated variety. The only concern, which is a small one, is down toward the far SW corner of the CWFA which will be close to the triple point and warm sector. There seems to be a small window of opportunity where some left over diurnal sfc based instability could coincide with some turning of the wind in the vertical near the front, to possibly allow for a wind gust or a spin up along the front. This would be possible until mid-evening. Locally heavy downpours will remain a threat with pwats approaching 2 inches tonight and Tue. The front will bring the initial wave of rain, and then the occluding low will bring additional rain overnight tonight and Tuesday morning. Some elevated instability will keep thunder chances possible. Showers and storms should become more scattered as the sfc low moves out, but the upper wave still has yet to move through. The favored area for additional showers and storms will be across the east, with a stabilizing flow off of Lake Michigan. A lingering shower will possible off of Lake Michigan Tue evening as another short wave moves through. We should see drier conditions move in for Wed and Wed night. Even though another short wave moves through from the NW, moisture will be quite limited by that time. .LONG TERM...(Thursday through Monday) Issued at 237 PM EDT Mon Aug 20 2018 Fair weather under sfc ridging and rising heights expected through the latter half of the week, with some warm advection showers arriving Friday evening and continuing into Saturday as short wave trough axis moves through. Showers should be tapering off Sunday in flat upper ridging. Temperatures will warm over the weekend as a sharp western CONUS trough results in heights building across the Great Lakes. A weak shortwave trough shears out as it tops the ridge on Monday and brings a low chance of showers. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 757 PM EDT Mon Aug 20 2018 VFR conditions this evening will trend down to predominantly MVFR overnight as showers and tstms increase in coverage with the approach of a low pressure system. Ocnl IFR conditions are also possible overnight where heavier showers occur. MVFR conditions are expected for much of Tuesday, with some morning IFR possible as the sfc low tracks through. Improvement toward VFR should occur late in the day as the low pulls away and showers end, but winds will be increasing from the north- northwest. && .MARINE... Issued at 350 PM EDT Mon Aug 20 2018 Kept continuity with the previous forecast and surrounding offices with the idea of having a Small Craft Advisory for this event, although there certainly could be gusts to gale force at times. The main messaging will be the dangers not only to boaters and swimmers but those walking on piers. The current high lake levels mean that waves over 5 feet, which are expected Tuesday afternoon into Wednesday morning, are capable of washing over piers and taking any sightseers out there with them. We will continue to message this via social media. Waves and winds decrease Wednesday and the expiration time of the SCA was unchanged. && .HYDROLOGY... Issued at 237 PM EDT Mon Aug 20 2018 Locally heavy rainfall will be possible with showers and storms through Tuesday. Precipitable water values will be approaching 2.00 inches through then. We expect that the higher values will not be widespread. This leads us to believe that widespread flooding will not be a problem. Localized areas could see some issues if some training of showers/storms occurs. The limited coverage of recent rainfall, and ongoing drought conditions will help to mitigate flooding potential a bit. Once we get to Tuesday afternoon, we should at least a brief break before the next batch of rain comes in && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Beach Hazards Statement from Tuesday afternoon through Wednesday evening for MIZ056-064-071. Beach Hazards Statement from Tuesday morning through Wednesday afternoon for MIZ037-043-050. LM...Small Craft Advisory from 11 AM Tuesday to 2 PM EDT Wednesday for LMZ847>849. Small Craft Advisory from 2 PM Tuesday to 8 PM EDT Wednesday for LMZ844>846. && $$ UPDATE...Meade SYNOPSIS...NJJ SHORT TERM...NJJ LONG TERM...Ostuno AVIATION...Meade HYDROLOGY...NJJ MARINE...Ostuno
Area Forecast Discussion
National Weather Service Huntsville AL
754 PM CDT Mon Aug 20 2018 .NEAR TERM...(Tonight) Issued at 754 PM CDT Mon Aug 20 2018 The airmass over north AL has greatly stabilized after earlier thunderstorms and rain-cooled air over central AL has begun to advect northward. This can be seen in the CAPE/theta-e fields. A larger scale outflow boundary from the central AL convection was noted on KGWX moving northwest into Lawrence and southeast Franklin County. Obviously, supercell convection over northern MS is being monitored closely feeding off very high ML-CAPE of 2000-3000 j/kg and effective deep layer shear of 30-35kt. It will be interesting to see how the outflow boundary interacts positively or negatively on the strength of the supercells in northeast MS. This activity will likely reach far northwest AL between 02-04Z in some form, and has been consistently forecast by the HRRR in doing so. However, the HRRR trends are also consistently weakening the convection rapidly between 04-08Z, likely not reaching most of our southeast forecast area, roughly southeast of BGF-HSV- Bankhead NF. The severity of the thunderstorms may give our western 3 counties a threat of damaging wind. Have adjusted overnight PoP to lower values in our southeast counties based on these trends. .SHORT TERM...(Tuesday through Wednesday night) Issued at 334 PM CDT Mon Aug 20 2018 Short term guidance suggests that the mid-level trough axis will cross the TN Valley region tomorrow morning, with flow aloft veering to north-northwest and increasing throughout the day. At the surface, a Pacific cold front should spread rapidly eastward through all but perhaps the southeastern counties by 18Z, with gusty west- southwesterly low-level flow developing in its wake. Any lingering deeper convection is expected to end rather quickly around or shortly after sunrise over northeast AL, although isolated light showers will be possible region-wide throughout the morning prior to the arrival of the Pacific front. Strengthening subsidence aloft will promote rapid drying of the column in the wake of the front, but lower clouds could potentially be slow to erode and for this reason we have forecasted max temps close to values from today. A northwest flow aloft will persist across the region for the remainder of the short term period, as latest NWP guidance indicates that the region will remain along the northeastern periphery of a strong subtropical ridge centered across eastern NM/western TX. Although a few weak mid-level disturbances will travel southeastward across the region in this regime, lift will be too weak to support development of precipitation based on the anticipated vertical moisture profile. A modified Canadian surface ridge will migrate eastward from the central High Plains into the OH Valley, with low- level flow gradually veering from northwest to northeast by Wednesday night. Although dewpoints will drop considerably, lows Thursday morning may not reach their full potential due to an increase in high clouds and elevated surface flow. .LONG TERM...(Thursday through Sunday) Issued at 334 PM CDT Mon Aug 20 2018 The center of the subtropical ridge is expected to build eastward across TX and into the lower MS Valley from Thursday through Friday, with northwest flow aloft diminishing with time. In the lower-levels east-southeasterly winds will begin to increase Friday morning as a strengthening surface ridge builds southward in the lee of the southern Appalachians. However, before this occurs, we anticipate strong radiational cooling on Thursday night, with lows predicted to range from the upper 50s in the northeast to the lower 60s elsewhere. Limited northward return of boundary layer moisture may promote a few showers and thunderstorms in the southeast on Friday afternoon, with a slight to low chance of afternoon convection expected on both Saturday and Sunday. However, as a result of strengthening subsidence beneath the building anticyclone aloft, we expect the coverage to be rather limited. Both max/min temperatures should warm steadily over the course of the weekend, with highs ranging from the upper 80s in the east to the lower 90s elsewhere. Unfortunately, as dewpoints slowly rise back into the lower 70s, Heat Index values will once again be in the 95-100 degree range for much of the region Saturday and Sunday. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 625 PM CDT Mon Aug 20 2018 Currently VFR conditions are prevailing across most of north AL/southern middle TN. Expect this to continue until showers and thunderstorms over N MS/W TN move east over next several hours. These storms could be strong to marginally severe mainly over NW AL (close to KMSL) with wind gusts up to 50 kts possible around the 03Z-05Z time frame. Have included a TEMPO group at KMSL for this potential but have not included the wind gusts yet due to coverage uncertainty. These storms should weaken as they approach north central AL/Southern middle TN. Then, anticipate IFR to MFR cigs to rapidly follow the storms until 15Z with wind gusts up to 20kts possible with prevailing westerly winds. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ NEAR TERM...17 SHORT TERM...70/DD LONG TERM...70/DD AVIATION...SL.77 For more information please visit our website at
Area Forecast Discussion
National Weather Service Wilmington NC
950 PM EDT Mon Aug 20 2018 .SYNOPSIS... Bermuda High will continue spreading warm and moist air over the region into Wednesday. Shower and thunderstorm chances will increase Tuesday and Wednesday, prior to a cold front crossing the region Wednesday night. Canadian high pressure will build in behind the front, bringing a drier and slightly cooler airmass for the end of the week and start of next week. && .NEAR TERM /THROUGH TUESDAY/... As of 900 PM Monday...Mid to upper trough extending down from the Upper Great Lakes down almost the full length of the Mississippi River will traverse slowly eastward overnight. At the same time, upper level ridging still holding on right up along the Southeast coast. This has helped to limit convection so far today over local area, with best convective activity in convergence along and ahead of front draped near the VA/NC border and near trough inland. Basically, aside from some fading sea breeze convection, area was only left with an isolated storm or two with more widespread activity mainly north of forecast area. Some debris clouds from convection just to our north will continue to stream across the area overnight. Models continue to show some shortwave energy rotating around longer wave trough, so can not completely rule out an isolated shwr/tstms overnight, but with loss of heating will leave coverage isolated at best. Continued hot and humid air mass with temps once again in the mid 70s for overnight lows most places. Previous discussion: Despite deep layer saturation seen in today`s 12Z RAOBs convection continues to be hard to come by. Granted there is little to no deep layer ascent but the fact that even surface forcing is not generating meaningful rainfall indicates that the the shortwave ridge currently crossing the area and the weak lapse rates in place are dominating. There is however some decent agreement with major guidance that this changes overnight at least for the coast as the WRF in particular shows a strong convective signal. Area- wide low chance POPs warranted tomorrow with some higher values over far interior zones where some southwesterly flow may start to impinge upon the area. && .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... As of 3 PM Monday...A pair of shortwaves will move through the Great Lakes and across New England this week. A thin axis of vorticity trailing well south of the first shortwave will move across the eastern Carolinas Tuesday night. Enough moisture and instability should be present that scattered showers and thunderstorms will persist along and ahead of the vort lobe. Confidence that we`ll see storms is increased seeing that that we`ll have the right-entrance region of a south-to-north 250 mb jet max overhead Tuesday night. 0-6 km shear around 20 kt should support weakly organized multicells, with overall cell motion toward the northeast at 25 mph. Behind the departing vorticity aloft, much drier mid-level air will overspread the eastern Carolinas Wednesday. While lapse rates will continue to be steep enough to support convection, all that dry air and unfavorable jet structure aloft has led me to trim PoPs back to 20-30 percent inland and only 40 percent in the seabreeze-enhanced area near the coast. It`s worth noting the GFS and ECMWF are considerably drier than the NAM with moisture through the 800-600 mb layer Wednesday, but all models show 0-6 km bulk shear values remaining good for this time of year. If we do get storms, the dry air aloft will get entrained into downdrafts enhancing the potential of strong, gusty winds. SPC has a small "marginal" risk area for the eastern Carolinas for this potential. As the second shortwave moves across New England Wednesday night, a cold front extending southward through the Mid-Atlantic will move into, and likely through, the eastern Carolinas late. Yes, this appears to be a true frontal passage with a wind shift and advection of modestly drier air beginning before sunrise Thursday. && .LONG TERM /THURSDAY THROUGH MONDAY/... As of 3 PM Monday...Cold front will be off the coast as the period begins. High pressure building in from the northwest is quickly moved east by progressive flow aloft. Lingering moisture along the coast Thu might support some isolated diurnal convection Thu afternoon/evening. Mid-level pattern transitions to flattened 5h ridge for the end of the week and start of next week. Weak coastal trough develops Fri night into Sat as the surface high drifts off the New England coast. The trough tries to move onshore but the combination of building mid-level ridge coupled with consolidation of the surface high over western NC and eastern TN keeps the trough at bay until it washes out, later in the weekend. Remnants of the trough combined with the sea breeze could lead to an increase in diurnal convection Sat through Mon. Following the passage of the cold front temperatures will run below climo through the weekend, rising to around climo as the period ends. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... As of 00Z...Convection hanging in there, mainly over North Carolina and a couple of counties in South Carolina. The HRRR has convection continuing through around 04-05Z. A secondary batch of showers is possible at the coastal terminals toward morning. Light southwest flow overnight. Tuesday, time height showers a reasonable amount of moisture and we should see convection breaking out once again around midday. Winds will become gusty by mid to late morning. Extended Outlook...TSTMS becoming more numerous, possibly strong to severe from Tuesday evening through Wednesday morning, as storm motion increases. Frontal passage occurs early Thursday with a drying trend and VFR conditions Thursday and Friday, and low level winds NNE-NE. && .MARINE... NEAR TERM /THROUGH TUESDAY/... As of 900 PM Monday...Southwesterly flow to continue through the period. The sea breeze has been making the coastal winds stronger than those further offshore according to buoy data. The gradient will tighten slightly heading into tomorrow but mostly over land. Wind and seas over the water will more or less stay steady state/unchanged. SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... As of 3 PM Monday...The Bermuda high will retreat farther off the coast this week. Low pressure moving through New England will drag a cold front southward and actually through the coastal Carolinas late Wednesday night. It appears this will be a true frontal passage with an actual wind shift expected before daybreak Thursday. Before the front arrives, breezy southwest winds 15 to occasionally 20 knots are expected, maintaining seas of 3-4 feet. The best chance of thunderstorms appears to be Tuesday night as an upper level disturbance moves across the area, then perhaps again Wednesday afternoon is storms can form within a rather dry airmass aloft. LONG TERM /THURSDAY THROUGH SATURDAY/... As of 3 PM Monday...High pressure building in behind the cold front will maintain northerly flow over the waters Thu. Northeast surge arrives Thu night with winds increasing to a solid 15 kt. Northeast flow remains on the high end of the 10 to 15 range Fri as gradient remains pinched. Gradient starts to relax Fri night as the center of the high shifts northeast and flow becomes more onshore for Sat. Seas 2 to 3 ft at the start of the period build to a solid 3 ft Thu night and Fri before dropping closer to 2 ft late Fri night and Sat as wind speeds decrease. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ NEAR TERM...MBB/RGZ SHORT TERM...TRA LONG TERM...III AVIATION...DL
Area Forecast Discussion
National Weather Service Lincoln IL
901 PM CDT Mon Aug 20 2018 .UPDATE... Issued at 901 PM CDT Mon Aug 20 2018 For the most part, the current forecast looks fine. Severe weather threat has diminished considerably across the CWA and all that is left is isolated to scattered showers and storms. Will be adjusting pops to account for current trend seen on the radar across the area. Winds will remain light and variable as well given the proximity of the sfc low. Update should be out shortly. && .SHORT TERM...(This evening through Tuesday) ISSUED AT 300 PM CDT Mon Aug 20 2018 19z/2pm surface analysis shows warm front north of the I-74 corridor, with scattered thunderstorms noted in the vicinity of the boundary across the far northern KILX CWA from near Bradford to Lexington. Front and its associated convection will lift into northern Illinois over the next 1-2 hours...leaving behind a warm/humid airmass with only isolated storms across central Illinois through late afternoon. Meanwhile, thunderstorms are increasing in coverage and intensity upstream across southeast Missouri into southwest Illinois. This activity is firing ahead of an advancing cold front within a moderately unstable/sheared airmass characterized by SBCAPES of 2500-3500J/kg and 0-6km bulk shear of 30kt. Based on radar trends and consistent HRRR output, it appears the storms will spread northeastward across the E/SE CWA mainly along/east of a Taylorville to Champaign line between 22z/5pm and 02z/9pm. Strong to potentially severe storms with damaging wind gusts will be possible. Have therefore carried likely PoPs across this area late this afternoon through mid- evening. Further west, areal coverage of convection will be considerably less, so have only gone with chance PoPs across the central/western CWA. Main push of convection will exit into Indiana by late evening, followed by a few lingering showers through the overnight hours. Much cooler weather will be on tap for Tuesday: however, with upper trough axis just east of the area over Indiana and weakly cyclonic flow persisting, cannot rule out a few showers. High temperatures will be in the upper 70s. .LONG TERM...(Tuesday night through Monday) ISSUED AT 300 PM CDT Mon Aug 20 2018 High pressure will bring cooler/drier weather into central Illinois for Wednesday and Thursday with highs in the middle to upper 70s and lows in the middle to upper 50s both days. As the high departs, a short-wave trough noted on latest water vapor imagery over Idaho will begin to approach from the northwest on Friday. 12z Aug 20 GFS/ECMWF are in excellent agreement with one another...with both models suggesting rain chances arriving along/west of the Illinois River late Thursday night...then spreading across the remainder of the area Friday/Friday night. Once the short-wave passes, upper heights will rise in earnest over the weekend as a pronounced upper ridge builds over the mid- Mississippi River Valley. As a result, temperatures will climb into the upper 80s and lower 90s Saturday through Monday. Models are hinting at potential MCS development over Minnesota/northern Iowa Sunday night which could possibly spill into north-central Illinois Monday morning. It is still too early to pin down the details with this scenario, but will feature low chance PoPs across the north on Monday to handle this. Main story this weekend through much of next week will be the a prolonged period of summerlike weather will develop. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 650 PM CDT Mon Aug 20 2018 VFR conditions are expected to start the evening, except at CMI where a storm will move through the area over the next hour. Then broken cigs at all sites are expected this evening. Widely scattered showers are around but will be keeping out of the sites until it appears the precip will get to the sites...and then will amend. Once this area of scattered precip moves out of the area tonight, lower clouds in the MVFR to IFR category will develop over the area overnight and into the morning hours. With cyclonic flow still over the sites tomorrow and cooler temps with lots of low level moisture, expecting MVFR cigs during the morning hours at all sites, along with VCSH. Winds will be variable through the period. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Auten SHORT TERM...Barnes LONG TERM...Barnes AVIATION...Auten
Area Forecast Discussion
National Weather Service Indianapolis IN
1146 PM EDT Mon Aug 20 2018 .UPDATE... The AVIATION Section has been updated below. && .SYNOPSIS... Issued at 237 PM EDT Mon Aug 20 2018 Low pressure over Iowa and Missouri is expected to push to Michigan and Indiana by Tuesday morning. This will bring showers and isolated thunderstorms to Indiana tonight. A cold front associated with the low is expected to push across the state on Tuesday. This will bring a chance for another round of precipitation on Tuesday before dry air begins to arrive on late Tuesday afternoon. Cooler and dry high pressure will arrive across Central Indiana Wednesday and provide dry weather for the rest of the work week. Showers look to return to the area on Friday night as another frontal system pushes into the Ohio valley. Showers chances look to linger across Indiana through the weekend. && .NEAR TERM /Tonight/... Issued at 851 PM EDT Mon Aug 20 2018 Mid level vorticity lobe currently arcing from eastern Illinois into far western Kentucky is expected to move into the western border zones over the next hour or so. Convection may increase in coverage over the next few hours as this feature moves into the area, and interacts with some enhanced flow at 850mb. Appears the highest threat for precipitation for the rest of the night will be between about 210200Z-210900Z, coinciding with the passage of the upper air feature. Deep layer shear remains marginally favorable for strong to severe storms for the balance of the night. Previous discussion follows. Surface analysis early this afternoon shows deep low pressure in place across southern Iowa. A warm front extended eastward from the low across Illinois to Central Indiana. Radar shows a wave of showers ahead of the warm front. Dew point temperatures across the area remained very the lower 70s. Water vapor showed an upper low was found across MO/IA. A plume of tropical moisture was streaming across the Deep south...through the Ohio valley and into the low. The GFS and NAM suggest this low pressure system will trek northeast toward lower Michigan tonight...keeping cyclonic flow across Central Indiana tonight. Forecast soundings again show good lift arriving across the forecast area tonight with good low and mid level moisture. HRRR suggests a wave of precipitation pushing across Indiana after 02Z. Forecast soundings suggest deep saturation overnight as this deep low passes to the north. Thus will trend nearly toward categorical pops tonight...particularly across the northwest where best forcing and dynamics will be best. Given the expected clouds and rain will trend low at or above the forecast builder blends. && .SHORT TERM /Tuesday through Thursday/... Issued at 237 PM EDT Mon Aug 20 2018 An Active weather morning will be expected on tuesday with a slow transition toward quiet and drier weather on Tuesday afternoon and Tuesday Night. Models suggest the upper trough axis and an associated cold front will push across the area early in the morning. Models show best forcing exiting the area prior to 12Z and moisture slowly decreasing through the day as the flow becomes more northwesterly. Forecast soundings show drying within the column as the afternoon progresses. Thus will start with some morning pops across the forecast area and trend lower as the day progresses...eventually dry by late in the day. Given the expected change in air mass will stick close to the forecast builder highs. The GFS shows strong mid level ridging over the upper midwest diving southward toward Indiana on Tuesday Night. This strong ridge axis and large high pressure system is expected slowly advect eastward into the Ohio Valley through Thursday. Forecast soundings. Forecast soundings on Tuesday night through Thursday show a very dry column...with a good mid level inversion. Thus only partly cloudy skies will be expected. Will stick close to the forecast builder blends on temperatures. && .LONG TERM /Thursday night through Monday/... Issued at 210 PM EDT Mon Aug 20 2018 Models in fair agreement and will be followed. A couple shots at rain and storms this period along with a return to quite humid and much warmer weather by the weekend. Surface high pressure that drops humidity across the region midweek moves east returning southerly flow Friday onward. Current upper trough in the Pacific NW will open up and track into our region Friday/Saturday bringing a chance for showers and storms late Friday, exiting late Saturday. A continuation of southerly flow will return dewpoints to the 70s for the weekend and heat indices well into the 90s. Diurnal heating in the renewed tropical airmass may trigger a shower or storm during peak heating Sunday into Monday. Blended temperature forecasts looked reasonable and were followed with a return from normal temperatures Friday to well above normal for the weekend and Monday. && .AVIATION /Discussion for the 210600Z TAFS/... Issued at 1145 PM EDT Mon Aug 20 2018 Mid level vorticity lobe currently moving through the area, combined with 25 kts of enhanced flow at 850mb, should allow for scattered convection in the vicinity of the terminals for the balance of the night. Convective threat should taper off after about 210900Z as the upper feature lifts off to the northeast. Brief IFR visibility restrictions and gusty shifting winds in and near the heavier cells. CB bases around 020. Otherwise, expecting low cloud development 008-012 towards sunrise in the wake of the mid level feature as the air mass stabilizes. These ceilings will probably linger into the mid to late morning hours. Surface winds 170-200 degrees at 5-9 kts overnight will gradually veer to 24-260 degrees at 9-13 kts by midday Tuesday. && .IND WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...Puma NEAR TERM...Puma/JAS SHORT TERM...Puma LONG TERM....Tucek AVIATION...JAS
Area Forecast Discussion
National Weather Service Midland/Odessa TX
552 PM CDT Mon Aug 20 2018 .DISCUSSION... Aviation concerns are below. && .AVIATION... Aside from thunderstorms affecting KFST through 21/01Z, VFR will prevail at all area terminals tonight and Tuesday. Winds will veer around to the southeast or south tonight/Tuesday morning, but generally be around 10kt. && .PREV DISCUSSION... /issued 206 PM CDT Mon Aug 20 2018/ The aforementioned cold front has pushed into the Trans Pecos with less unstable conditions noted across the PB/SE NM. Best SB instability is focused across the Trans Pecos where insolation has been good most all day and in Lower Trans Pecos where dewpoints are high - U60s! Visible imagery shows an MCV tracking s from the far wrn PB. HRRR initiates scattered storms across the Trans Pecos which could persist until early evening, heavy rain and downburst winds are the main concern. Visible imagery also shows TCU bubbling from the srn PB into the Trans Pecos. We made some changes to PoPs for remainder of afternoon and early evening to shift higher PoPs farther s. After this evening the chance for rain markedly decreases as the ridge to the w builds e resulting in a gradual but noticeable hotter trend. By Fri PM 7h temperatures across most all of the CWFA are >12C and near 30C at 85h, thus triple digit highs are likely ahead. The center of the anticyclone will be e over the weekend and high temps may back off a couple of degrees, but temperatures still well above normal. Depending on how far e and how long the ridge stays e will determine whether or not SHRA/TSRA will creep into the wrn CWFA next week. && .PRELIMINARY POINT TEMPS/POPS... Big Spring 74 97 75 98 / 0 10 0 0 Carlsbad 71 96 71 96 / 10 10 0 0 Dryden 74 98 74 98 / 20 10 0 0 Fort Stockton 71 95 71 96 / 20 10 0 0 Guadalupe Pass 67 90 67 90 / 10 10 0 0 Hobbs 68 94 69 94 / 0 10 0 0 Marfa 61 90 62 89 / 20 10 0 0 Midland Intl Airport 74 97 74 98 / 10 10 0 0 Odessa 74 97 74 98 / 10 10 0 0 Wink 74 98 73 99 / 10 10 0 0 && .MAF WATCHES/WARNINGS/ADVISORIES... NM...None. TX...None. && $$ 99/99/
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
1035 PM EDT Mon Aug 20 2018 .SYNOPSIS... A weak cold front near the northern sections will lift north tonight and Tuesday. Another cold front will move through the area late Wednesday night and Thursday, then stall off the coast into next weekend. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... As of 1030 PM Monday...Only minor adjustments to overnight forecast with highest POPs over NW sections next few hours as current activity moves NE with some mid-level warm front action. Latest HRRR and NAM12 support scattered activity possible across most of area 2 AM-8AM thus 40-50% POPs all areas that period. Minor adjustments for convective debris cloud cover into overnight. Temps on track. /Previous discussion/ As of 240 PM Mon...Convection beginning to increase over the region and expect good coverage into the evening given moist unstable air over the region. Locally gusty winds and very heavy rain a good bet with stronger storms. Instab will diminish a bit overnight but mdls show decent coverage of shra/tsra cont...kept good chc in most areas with again threat for locally very heavy rain...poor drainage flooding. Lows in the 70s. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/... As of 240 PM Mon...Sct to numerous shra and storms expected again with little change in airmass. Mid lvl flow is a bit stronger Tue as short wave crosses well to the NW. If get enough heating and instab could have a cpl severe storms and as usual the threat for heavy rain in spots. Cont with likely pops inland to chc closer to coast in the aftn with highs mostly 85 to 90. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... As of 3 AM Mon...Unsettled for the first part of the week, then a cold front will push through the area Wednesday night and Thursday with drier air moving into the area and precip chances becoming more isolated to widely scattered. Tuesday Night and Wednesday...Surface low will continue to strengthen and move through the Great Lakes as attendant cold front approaches from the west. PWATs climb to around 2.3 inches Tuesday evening, with 0-6 km shear increasing to 20-30 kt. Isolated strong to severe storms with damaging wind gusts and locally heavy rainfall will be possible in the evening. Scattered showers and storms will continue Wed, though heavy rain threat expected to wane as airmass becomes much drier aloft. Highs in the mid to upper 80s, with lows in the 70s. Wednesday night through Sunday...A cold front will push through the area Wednesday night and Thursday, then likely stall off the coast into the weekend as strong high pressure builds in from the north. A much drier and more pleasant airmass will move into the area. Expect precip chances to diminish as well, though will continue sc/low chance pops along the coast near axis of better moisture. Expect temps below normal, with highs in the low to mid 80s and overnight lows in the 60s to low 70s. Some guidance has lows dropping into the upper 50s to low 60s inland Fri and Sat mornings. Upper ridge will strengthen over the area late weekend into early next week as surface high remains centered just to the west. Temps will gradually warm with precip chances returning to near climo. && .AVIATION /03Z TUESDAY THROUGH SATURDAY/... Short Term /through 00Z Wed/... As of 800 PM Monday...Cluster of tstms with sub-VFR conditions is in between TAF sites but will likely spread NE and affect mainly KISO and KPGV next 1-3 hours. Scattered convective threat will continue all sites through the night but will handle mainly with VCSH. Otherwise, VFR expected into overnight hours with some sub-VFR CIGs/VSBYs possible around sunrise. Mainly VFR again during the day Tuesday with scattered shower threat in morning and tstm threat in afternoon. Long Term /Tuesday night through Friday/... As of 3 AM Mon...Scattered to numerous showers and storms will produce sub-VFR conditions at times Tuesday night and Wednesday, best chances during the afternoon and evening hours. A cold front will push through the area Wednesday night and Thursday, with a drier airmass moving in behind it for late week. && .MARINE... Short Term /through Tue/... As of 1030 PM changes with update. /Previous discussion/ As of 240 PM Mon...Weak front near nrn tier will lift N tonight with pred SW flow 5 to 15 kt N and 10 to 20 kt S. Gradient begins to tighten Tue ahead of approaching cold front and SSW winds will increase to 15 to 20 kts with gusts approaching 25 kts late. Seas will be in the 2 to 4 foot range tonight building to 3 to 5 feet Tue. Long Term /Tuesday night through Friday/... As of 3 AM Mon...SCA conditions likely late Tue night into Wed. Gradient conts to tighten Tue night and Wed, with SW winds increasing to 15-25 kt and seas building to 3-6 ft. SCA conditions likely to develop across the waters and Pamlico Sound late Tue night and Wed. A cold front is likely to push through the waters Thursday then stall off the coast into the weekend. Winds will shift becoming NE/E 5-15 kt Thu, and then move easterly 10-15 kt Fri with seas 2-4 ft. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...None. MARINE...None. && $$ SYNOPSIS...RF NEAR TERM...RF/JBM SHORT TERM...RF LONG TERM...CQD AVIATION...RF/JBM/CQD MARINE...RF/JBM/CQD
Area Forecast Discussion...CORRECTED FORMATTING
National Weather Service Twin Cities/Chanhassen MN
722 PM CDT Mon Aug 20 2018 .SHORT TERM...(This evening through Tuesday) Issued at 248 PM CDT Mon Aug 20 2018 Main concern is overall convective trends overnight and possible stratus/fog development after midnight. Latest SPC mesoanalysis showing an area of MLCAPES around 1000J/kg moving across a small portion of east central MN. This continues to wrap southeast in overall forecast through about 00z or so. HRRR trends have continued to show widely scattered development in this area through, although coverage is decreasing. Otherwise, progression of the upper low and its attendant rain shield has been slow to lift into southern MN and appears to be as far north as it will be for the event. Will have to trim PoPs over a portion of southern MN. Overall, it appears the precipitation threat will end by 03z. Following that, clouds will linger and models continue to trend stratus/fog development over the eastern portion of the cwa overnight. SREF probabilities for low clouds where greater that 90% again with lower probabilities for lower visibility. Will mention patch fog for now. An area of smoke is rotating s-sw over the area and with mixing this afternoon, some of the smoke has reached the ground. THis may continue into TUesday as well. The MPCA issued an Air Quality Alert earlier and continued through 9pm Tuesday over much of central/southern MN. For Tuesday, the latest models have trended another weak short wave dropping in behind this latest upper low. This will bring in some clouds and perhaps a small threat of isolated showers to central MN Tuesday afternoon. At the moment we will go dry with deeper moisture lacking and rather weak instability. && .LONG TERM...(Tuesday night through Monday) Issued at 248 PM CDT Mon Aug 20 2018 Westerly flow aloft develops for the remainder of the week and results in dry and mild conditions through Thursday as surface high pressure builds across the central CONUS. High temperatures will mostly range from 75-80 degrees on Wednesday and Thursday. Late Thursday and Friday both GFS and ECMWF models continue to advertise the progression of a healthy mid-level shortwave across the Upper Midwest. Temporal progs have trended slightly slower with this feature, but still look to impact the area with showers and thunderstorms in the Thursday night through Friday time frame. Have retained likely (60-70 percent) POPS. Saturday currently looks to be our break day between systems, although we look to see warmth and humidity building back slightly as high temps moderate into the mid 80s and dewpoints creep into the 70s ahead of a High Plains trough. Some weak mid-level energy and low level warm air advection are progged for Sunday into Monday, so low precipitation chances have been included then as well. Model solutions are still highly variable over the weekend with regard to where synoptic features setup, so confidence is still low at this point. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 722 PM CDT Mon Aug 20 2018 Scattered showers continue across eastern MN and WI early this evening, but they should diminish in the next few hours. VFR conditions expected for most of the evening, but smoke and light fog may begin reducing visibilities to MVFR levels late this evening. MVFR/IFR stratus will develop across areas near and east of RWF and STC overnight, and lift by Tuesday afternoon. KMSP...Light showers persist for the next hour or two, then dry for the rest of the period. MVFR conditions are expected to arrive sometime around 09Z overnight. /OUTLOOK FOR KMSP/ Thu...VFR with TSRA possible overnight. Wind SW 10-15 kts. Fri...Chc MVFR/TSRA. Wind SE at 10G20 kts. Sat...Chc MVFR early. Wind S 5 kts. && .MPX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. && $$ SHORT TERM...DWE LONG TERM...LS AVIATION...BORGHOFF
Area Forecast Discussion
National Weather Service Phoenix AZ
218 PM MST Mon Aug 20 2018 .UPDATE...Updated Fire Weather Discussion. && .SYNOPSIS... Substantial moisture returns to the region this evening bringing a chance of showers and thunderstorms to all areas of south-central AZ tonight through Tuesday. The upper level flow pattern then shifts to the southwest on Wednesday bringing some drying and lower grade monsoon conditions Thursday and Friday. Storm chances will remain across portions of south-central Arizona during this period but will mostly be focused across the higher terrain north and east of Phoenix. && .DISCUSSION... A look at the upper level pattern this afternoon reveals high pressure is currently moving over eastern Arizona and into New Mexico. This is acting to shift our steering flow to the southeast which is already allowing moisture from Mexico to stream into our area. The 12Z sounding from Phoenix today shows PWs are already up 0.5 inches from just 12 hours ago while the upper level 700 mb flow has shifted to the southeast. There is excellent agreement between mesoscale models that deep convection will begin over southern AZ/northern Sonora this afternoon, aided by the increase in moisture, and then subsequently send an outflow boundary to the north towards Phoenix around 8 pm this evening. New convection could fire off on this outflow as it moves northwest but should also weaken as it does so. The reasoning here lies within the increasing CIN to the north with about 100 J/kg forecast around Phoenix this evening. Several runs from the HRRR model did show convection making it into Phoenix this evening, however, this model remains an outlier. So while storms are unlikely for the metro, they are certainly not out of the question. A secondary wave of convection will quickly follow tonight associated with a shortwave rotating up through Mexico. Nearly all models show some activity overnight in south-central AZ, however, there are differences in timing and location. Some solutions point to weak overnight convection beginning as early as midnight to as late as 5-8 AM Tuesday morning. At this point, convection will most likely be centered over Maricopa County Tuesday morning but it is not out of the question for this area to shift a bit west or east as it rotates through. One thing to note is that moisture will be high, between 1.75 and 2.0 inches, so whatever does develop will be very efficient at producing heavy rain. Although, the GFS shows the steering flow around 10 to 20 kts so flash flooding should remain isolated and not widespread. Depending on how Tuesday morning plays out will largely influence what will happen in the afternoon. Several models show considerable cloudiness over our area from the morning through much of the afternoon. This will undoubtedly put a damper on afternoon convection with storms being confined to the higher elevations and locations that do clear out early enough. The aforementioned upper level high will continue shifting eastward on Wednesday with our flow aloft turning solely out of the southwest. This will bring drier air into the region, but we should still have sufficient moisture for afternoon and evening storms mostly across the high terrain north and east of Phoenix. Similar conditions are seen for Thursday and Friday. Temperatures will remain fairly steady through the rest of the week as 500mb heights lower from 594dm on Wednesday to 588dm on Saturday. These lower heights are due to a developing Pacific low well off the California coast. Though it is around a week away, both the GFS and European show a more significant Pacific trough digging southeastward into the Pacific Northwest early next week. This will definitely be something to watch for the middle part of next week. && .AVIATION... South-Central Arizona including KPHX, KIWA, and KSDL: As we transition back into a little more active storm regime, expect a chance of showers and storms in the region beginning tonight around 04Z and continuing on and off through Tuesday afternoon. Expect periodic episodes of gusty southwesterly to southeasterly outflow winds beginning tonight around 04Z with gusts of 20-28kt. Nighttime visibilities may also be temporarily reduced to 3-5sm in areas of blowing dust from the south, although not to the extent of including them in the TAFs. Expect BKN-OVC decks from 8-10kft on Tuesday morning near 15Z with thunderstorms in the vicinity. For this afternoon no impacts are expected with breezy westerly winds at 6-12kt gusting to 15-18kt. Otherwise skies will be partly cloudy FEW-SCT decks at 10-16kft and BKN high clouds near 20- 25kft. Southeast California/Southwest Arizona including KIPL and KBLH: Expect moderate to very breezy southerly winds at KBLH near 10-15kt with gusts to 22-27kt through most of the period. The winds at KIPL will favor the southeast to south near 7-12kt. Skies will be mostly clear with FEW-SCT high clouds near 20kft. Aviation Discussion not updated for amended TAFs. && .FIRE WEATHER... Thursday through Monday : As Monsoon conditions continue expect the best chances for thunderstorms to be focused over the high terrain areas north and east of Phoenix along with continued slight chances of storms over the lower deserts. Max temperatures are expected a little below normal through the period. Min RH values across SE CA will stay in the mid to upper teens and above or well above 20 percent elsewhere. Overnight recover will be fair across SE CA and good to excellent elsewhere. Expect typically breezy upslope winds each afternoon. $$ && .SPOTTER INFORMATION STATEMENT... Spotters should follow standard reporting procedures. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ DISCUSSION...Wilson/Kuhlman AVIATION...Sawtelle FIRE WEATHER...Sawtelle
Area Forecast Discussion
National Weather Service Pueblo CO
332 PM MDT Mon Aug 20 2018 .SHORT TERM...(This evening through Tuesday) Issued at 332 PM MDT Mon Aug 20 2018 ...Smoke then Storms... Main weather feature today has been the smoke. It`s really hard to tell exactly where all the smoke is coming from because there are so many fires over the western U.S. and Canada that have all merged into one massive smoke layer over the western U.S. In any event, smoke modeling shows the smoke holding on through this evening and then moving off to the east, in large part, as monsoonal moisture and disturbances begin to move in from the west. There may still be some smoke around late tonight and Tuesday but it should be a lot less. On Tuesday, we turn our attention to an influx of monsoonal moisture and disturbances that may produce some severe weather across parts of the plains Tuesday afternoon. Models have been pretty consistent on this so confidence is increasing. Also increasing, is the shear forecast off of the models. The 12z run of the 12 km NAM now has 45 to 50 kts of bulk shear across much of the plains east of the I-25 corridor, and now, also, along the Palmer Divide. The convective allowing high-res models are sending lots of convection east across the forecast area Tuesday. One round of convection moves across the mountains, Pikes Peak Region and Palmer Divide during the morning into the early afternoon hours. Then, additional, more intense convection moves across the mountains and plains during the mid and late afternoon hours. Shear values are greatest across the plains east of the I-25 corridor and also along the Palmer Divide. So, these would be the areas to watch for the greatest severe potential. In particular, the HRRR and NAM NEST are targeting Las Animas and Baca Counties and to some extent Bent, Prowers and Kiowa Counties for the greatest potential for severe weather. There are even indications of a convergence zone setting up along the Palmer Divide that could help develop a supercell along or north of the Palmer late Tuesday afternoon. The axis of maximum CAPE (2000-3000 J/kg) during the afternoon will be over eastern Las Animas and Baca Counties at 21z. By 00Z, the axis stretches northward and extends into northeast El Paso County, where values range from 500-1000 J/kg. So, there is certainly enough CAPE for deep, strong convection across the southeast plains. The amount of CAPE across northern El Paso County is not exceptional but it is still sufficient for strong to severe convection, especially if the shear is there. All severe weather types will be possible from storms tomorrow, including the possibility of a tornado, particularly across Las Animas and Baca Counties, where high-res models are showing the best updraft helicity tracks. An additional concern Tuesday will be for flash flooding on burn scars. While storms should be easterly moving at 15-25 mph Tuesday, a strong storm over a burn scar could still cause flash flooding. .LONG TERM...(Tuesday night through Monday) Issued at 332 PM MDT Mon Aug 20 2018 ...Active weather continues Tuesday night through Wednesday... Tuesday night-Wednesday night...Lastest models in good agreement of keeping an active weather pattern across the area through the day Wednesday, with monsoonal moisture embedded within west to southwest flow aloft, combines with a broad upper trough progged to translate across the Rockies through the period. Models continue to support widespread showers and storms ongoing over and near the higher terrain Tuesday afternoon, with storms spreading east across the far Southeast plains evening, where a weak surface low and boundary moving southeast through the evening, will help spread low level moisture westward back across the I-25 Corridor overnight. This boundary will also support the potential for severe storms through the evening, with large hail, damaging winds and even a tornado possible, especially across portions of Las Animas, Bent, Prowers and Baca Counties. With moist upslope flow expected across the Plains overnight, along with tail end of embedded shortwave ejecting across the Rockies, will keep isolated to scattered pops in place across the area overnight. Could see a brief lull in activity early Wedensday morning, before the next ejecting wave starts to move into western Colorado, with more scattered storms expected to develop over the higher terrain late Wednesday morning, spreading east across the immediate adjacent plains through the afternoon hours and across the far southeast Plains once again Wednesday evening, as said wave translates into the High Plains. Westerly steering flow of 20 to 30 kts will limit flash flooding, however, with the ample atmospheric moisture in place, and the possibility of training storms, will need to watch for flash flooding on area burn scars through this period. Temperatures through the period look to be near to well below normal, with highs Wednesday in the mid 60s to mid 70s across the Plains. Thursday-Friday...Drier air progged to move across the area within moderate westerly flow aloft across the state, as last piece of energy translates across the Rockies Thursday, pushing the monsoonal moisture plume well south and east of the area. Best chances of showers and storms to be across the ContDvd Thursday afternoon, with lesser coverage of storms expected areawide on Friday. Temperatures look to warm back to near seasonal levels through Friday. Saturday-Monday...West to southwest flow aloft progged across the region through the weekend and into early next week, with upper high pressure across the Southern High Plains starts to spread monsoonal moisture back across the Rockies. Best available moisture looks to be along and west of the ContDvd, keeping the best chances of precipitation over the higher terrain into early next week. Temperatures this weekend look to be at and above seasonal levels, with highs in the mid 80s to mid 90s across the lower elevations, and mainly in the 60s and 70s across the higher terrain. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 332 PM MDT Mon Aug 20 2018 Generally dry across the flight area through tonight. There could be a spotty evening shower or storm over the higher terrain but any such occurrence should be highly localized. Tuesday morning, monsoon moisture will increase from the west leading to the development of a few showers and storms along the Continental Divide. Tuesday afternoon, monsoonal moisture and disturbances will track from west to east across the flight area, triggering scattered showers and thunderstorms. A few severe thunderstorms will be possible across the plains Tuesday afternoon with primary threats of large hail, damaging winds and possibly a tornado. Otherwise, storm threats will include lightning, wind gusts to around 50 mph, small hail and locally heavy rain. The KCOS, KPUB and KALS terminals should all see VFR conditions through 18z Tuesday. After 18z, thunderstorms will be possible at each of the sites through the afternoon. Generally dry across the flight area through tonight. There could be a spotty evening shower or storm over the higher terrain but any such occurrence should be highly localized. Tuesday morning, monsoon moisture will increase from the west leading to the development of a few showers and storms along the Continental Divide. Tuesday afternoon, monsoonal moisture and disturbances will track from west to east across the flight area, triggering scattered showers and thunderstorms. A few severe thunderstorms will be possible across the plains Tuesday afternoon with primary threats of large hail, damaging winds and possibly a tornado. Otherwise, storm threats will include lightning, wind gusts to around 50 mph, small hail and locally heavy rain. The KCOS, KPUB and KALS terminals should all see VFR conditions through 18z Tuesday. After 18z, thunderstorms will be possible at each of the sites through the afternoon. && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...LW LONG TERM...MW AVIATION...LW
Area Forecast Discussion...CORRECTED
National Weather Service Charleston WV
918 PM EDT Mon Aug 20 2018 .SYNOPSIS... A warm front lifts north tonight, followed by one or more cold fronts Tuesday. Cool, moist, low level northwest flow on Wednesday. High pressure Thursday and Friday. && .NEAR TERM /THROUGH TUESDAY/... As of 830 PM Monday... Updated forecast to lower PoP per radar and satellite trends upstream across eastern KY. Only expect isolated light showers overnight. Removed thunder as well through 12Z Tuesday, except over portions of southeast OH. Allowed for periods of clearing despite for few mid to upper level clouds passing through. If this clearing materializes, dense river valley fog could develop overnight. Added some fog in weather grids. As of 230 PM Monday... Multiple cold fronts associated with this system approach and cross Tuesday, with showers and thunderstorms. The early timing of more numerous showers and thunderstorms, even during the overnight hours over the middle Ohio Valley, will limit instability Tuesday, even as bulk shear increases. The associated upper level crosses late Tuesday, but the last of the cold fronts is progged to possibly lag behind the short wave. If we could get heating at some point Tuesday afternoon, then associated upper level cooling may be sufficient to convert the increased bulk shear for strong to severe thunderstorms. A warm, muggy night is on tap tonight, as the warm front pushes through, and then temperatures on Tuesday will be largely dependent upon the timing of rounds of showers and thunderstorms coming through. && .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... As of 250 PM Monday... Surface low to move across the Great Lakes with cold front at the surface Tuesday evening. Forecast area will be located in the warmer and moist unstable air ahead of frontal passage. Moderate instability and low-level shear, especially in vicinity of front will allow a few strong thunderstorms to develop. Main impacts will be damaging winds as mid level flow increases through the day. A mid level post frontal trough will traverse on Wednesday, bringing another round of precipitation. After that, surface high pressure build in with ridging taking place by Thursday. && .LONG TERM /THURSDAY THROUGH MONDAY/... As of 250 PM Monday... Mid level flow becomes more zonal into the weekend with 5H trough lifting north of the Great Lakes. Followed central guidance with some tweaks for Wednesday night as blends where a little tardy in clearing precipitation east of the region. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... As of 807 PM Monday... Visible satellite imagery show mostly clear skies downstream across northeast KY, with few mid to upper level clouds passing by before sunset. Depending on the cloud cover, as areas of clearing could produce enough radiational cooling, together with weak BL winds, IFR dense fog formation could be possible, mainly along the river valleys overnight. Otherwise, MVFR ceilings could linger across the northeast mountains, and VFR conditions should prevail elsewhere. This thinking is contrary to all guidance that shows plenty of clouds, showers and storms tonight, except for the high resolution model HRRR which brings dry conditions. So confidence is medium counting with my gut feelings. The probability of pcpn has been lowered. Removed thunder from TAF tonight as can not find any substantial forcing mechanism to sustain strong updrafts. An approaching low pressure system will adopt the old frontal boundary south of the area, and produce a warm front that should lift slowly north into our northern sections by 12Z Tuesday. Showers and thunderstorms will become more numerous Tuesday, as a cold front approaches from the west. The lower atmosphere could decouple to produce light to calm winds overnight. Winds will become south to southwest on Tuesday, becoming gusty during the afternoon along thunderstorms. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z WEDNESDAY... FORECAST CONFIDENCE: Medium. ALTERNATE SCENARIOS: Coverage of storms could vary on Tuesday. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. DATE TUE 08/21/18 UTC 1HRLY 00 01 02 03 04 05 06 07 08 09 10 11 EDT 1HRLY 20 21 22 23 00 01 02 03 04 05 06 07 CRW CONSISTENCY H H H H H H H M M L L M HTS CONSISTENCY H H H H H H H H H H H H BKW CONSISTENCY H H H H H M M M H H H H EKN CONSISTENCY H H H H M M L L L L L L PKB CONSISTENCY H H H H H H H M H H H M CKB CONSISTENCY H H H H H H H H H H H H AFTER 00Z WEDNESDAY... IFR in showers and thunderstorms possible Tuesday night, and in stratus overnight Tuesday night into Wednesday morning.. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...JSH/RPY/TRM NEAR TERM...TRM/ARJ SHORT TERM...KMC LONG TERM...KMC AVIATION...ARJ
Area Forecast Discussion
National Weather Service Blacksburg VA
943 PM EDT Mon Aug 20 2018 .SYNOPSIS... There will be a good chance of showers and thunderstorms across the Appalachians and central mid Atlantic region until a cold front moves through Tuesday night. A large area of high pressure will then build in from the midwest and bring much drier and pleasant conditions to the region for the end of the workweek. && .NEAR TERM /THROUGH TUESDAY/... As of 940 PM EDT Monday... Flash Flood Watch will remain in effect through 6AM. Band of showers and thunderstorms across North Carolina continued to move northeast this evening. Short term models suggest this feature will continue through at least 2AM but may be weakening after midnight. Still the potential for localized high rainfall rates so no changes to the Flash Flood Watch at this time. Only minor adjustments to overnight lows. Low pressure moving up into the Great Lakes will push a cold front into the region from the west Tuesday. Indications are that effects of the wedge will continue to produce enough shear for organized convection while the dynamic environment results in enhanced lift and surface based instability increases. This should generate robust convection with some severe thunderstorms possible through early tomorrow evening. There will also be a continued threat for heavy rainfall but will wait to see where heavy rain falls tonight before determining if any additional flash flood watches are necessary. Conditions tonight will remain on the mild and muggy side while highs Tuesday will be close to normal. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/... As of 320 PM EDT Monday... In terms of highlights, strong to severe thunderstorms will in all likelihood still be marching eastward across the Piedmont very early in the short-term period (early Tuesday night). A more spatially limited convective threat may exist on Wednesday afternoon, preceding a significant air mass change toward cooler and drier weather that settles in late Wednesday night into the rest of the week. Convection in association with a pre-frontal surface trough, tied to filling surface cyclone in the St. Lawrence River Valley and parent deamplifying shortwave trough, should be progressing east across the foothills/Piedmont region by mid-evening Tuesday. Storms may still be on the strong side through this period, but should be exiting rather quickly east. The passage of this trough isn`t likely to result in much change in terms of temps or humidity level, but it will shift winds to the west allowing for some clearing into the overnight. The exception is in the west slopes of the Appalachians where some residual low clouds/stratus project to linger. Lows mainly in the 60s, warmest further east. We`ll then await the passage of the primary cold front/850 mb thermal gradient. This front appears to clear the western mountains/Blue Ridge by early afternoon with little fanfare ahead of it. Across the VA/NC Piedmont and Southside though, heating of a continued rather moist air mass per the NAM should result in about 1500-2000 J/kg of surface-based CAPE, along with favorable west- southwest deep-layer shear vector magnitudes around 35 to 40 kts. GFS on the other hand clocks in CAPE values about half as much. Though I think storm coverage is more isolated to widely scattered at best within an area from Yadkinville to Lynchburg east, it wouldn`t surprise me if one or two become strong in this corridor, particularly if the level of instability more closely follows the NAM. Only real impact in the west is lowering dewpoints and increasing northwest winds/gusts by afternoon due to pressure rises and deeper mixing. May see gusts approach 30 mph at times in the mountains late afternoon. Clearing and dry advection anticipated for overnight. More variation in highs Wednesday with clouds/stratus leading to cooler low 70s in the far west into southeast WV, to the mid/upper 80s as one progresses eastward into the foothills and Piedmont/Southside. Should see good radiational cooling Wednesday night with lows in the 50s to low 60s. Thursday really is a top-notch day areawide as sprawling high pressure area builds to our north with upper-level ridge in place. 850 mb temps take a tumble into the upper single digits to low teens, with surface dewpoints falling in lockstep into the 40s/mid 50s. This should prove to be a much more refreshing change compared to the soupy air we`ve been stuck in the last couple days. Plentiful sun should support highs largely in the 70s to low 80s. Clear skies anticipated for Thursday night as well, and a better potential for radiation fog as winds will be lighter than prior nights. Lows Thursday night should be in the 50s, and may approach the mid/upper 40s in the sheltered mountain valleys in far southwest VA. Overall forecast confidence is moderate, though higher confidence for Thursday. && .LONG TERM /FRIDAY THROUGH MONDAY/... As of 320 PM EDT Monday... Friday is pretty much a carbon copy of Thursday, as high pressure centered over Cape Cod/southern New England will extend a ridge along or just east of the Appalachians. Only real nuanced changes are that surface winds become more easterly and 850 mb temperatures are a degree warmer than Thursday. Pattern then begins to undergo some change into the weekend and early next week. Much of the weekend should be dry, but during the weekend longer-range forecast guidance build a large ridge associated with warmer temperatures which will eventually settle across the mid-Mississippi Valley. The period of more comfortable and cooler weather should then change to a more typical summer regime with daily chances for showers and thunderstorms. Temperatures should tend to be below normal initially, but by Sunday into early next week temperatures will then trend above normal along with an increase in humidity levels. && .AVIATION /02Z TUESDAY THROUGH SATURDAY/... As of 740 PM EDT Monday... Band of showers and thunderstorms moving northeast out of western and central North Carolina is expected to reach KDAN, KROA and KBCB after 03Z/11PM. HRRR and WRFarw had similar timing of this precipitation. Low confidence if there will still be thunder at that time and heavy rain producing MVFR to IFR visibilities is much more likely. Also overnight, stratus will redevelop with IFR to LIFR ceilings after midnight. Average confidence on timing of when ceilings will lower. Ceilings will remain low until well after sunrise. Similar to Monday, it may take most of the morning for KROA and KLYH to improve. But with a cold front approaching and southwest surface and low level winds increasing, conditions will return to VFR in the afternoon. Showers and thunderstorms along the front may impact KBLF and KLWB after 18Z. Lower confidence about the timing of the storms reaching the other area TAF sites before 00Z. Extended Discussion... High pressure will build in Wednesday and will be overhead by Thursday. VFR conditions are expected with this cooler and drier air mass through Friday. MVFR to IFR fog is possible for a few hours each night along and near the typical river valleys, especially west of the Blue Ridge. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...Flash Flood Watch until 6 AM EDT Tuesday for VAZ014>017-022- 032-033-043-044-058. NC...Flash Flood Watch until 6 AM EDT Tuesday for NCZ001>006- 018>020. WV...None. && $$ SYNOPSIS...MBS NEAR TERM...AMS/MBS SHORT TERM...AL LONG TERM...AL AVIATION...AMS/MBS