Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/16/19

National Weather Service Wakefield VA
957 PM EDT Wed May 15 2019 .SYNOPSIS... High pressure slides off the Southeast coast overnight. A weak cold front approaches from the north and clips the coast early Thursday morning. High pressure prevails off the Southeast coast Friday through the weekend...bringing unseasonably hot conditions. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... As of 955 PM EDT Wednesday... Upper air analysis reveals an upper level trough over Atlantic Canada this evening. At the surface, weak high pressure is centered just offshore of the Southeast CONUS, with low pressure now well offshore of Nova Scotia. Sky has become partly cloudy inland after a clear to mainly clear start this evening. Temperatures have fallen off into the 50s to near 60 degrees along the lower eastern shore. To the north, showers in association with a weak trough will drop SE across the northern mid-Atlantic late tonight/early Thu, and this will result in increasing mid and high clouds overnight, especially N. Forecast low temperatures tonight range from the upper 40s/around 50F from the Piedmont into interior s-central VA/NE NC, with low/mid 50s Nrn Neck to Ern Shore (with more cloud cover) and over coastal SE VA/NE NC. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/... As of 345 PM EDT Wednesday... The aforementioned trough digs off the Mid-Atlantic coast 12-15z Thursday, and a weak cold front clips the Delmarva. Moisture is limited, so PoPs are aob 20%, but CAMs do depict sct quick moving showers moving across the MD Ern Shore Thursday morning. The flow aloft will remain NW Thursday, and the low- level flow will briefly become WNW or NW behind the front, before becoming SW by aftn. Forecast high temperatures range from around 80F inland W of the Bay, to the low/mid 70s toward the coast. High pressure settles off the Southeast coast Thursday night into Friday with a warming trend continuing. 850mb temperatures rise to near 15C Friday along with low-level WSW flow. This should result in much warmer (or even hot) temperatures, with current forecast highs in the mid/upper 80s, with some readings around 90F possible, and slightly cooler along the immediate Atlantic coast. There could be some residual cloud cover in NW flow aloft (mainly N), and some isolated convection is possible (mainly along sea/bay breeze boundaries). A weak front drops across the Delmarva Friday night, and some showers/tstms could accompany this boundary in NW flow aloft. However, Pops are only 20-30% at this time. Very warm Friday night with low temperatures in the mid 60s to around 70F. Remaining very warm Saturday, with highs in the upper 80s to near 90F inland W of the Bay. An onshore component to the will will result in highs in the upper 70s to low 80s over the Ern Shore, and low/mid 80s for the wrn shore of the Bay and coastal SE VA/NE NC. Isolated showers/tstms may develop along sea/bay breeze boundaries Saturday aftn. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... As of 330 PM EDT Tuesday... Sub-tropical ridge remains over/in the vicinity of the region as a potent upper level low moves through the Plains/Midwest before moving towards the western Great Lakes. This upper level low slides well north of the region Monday into Tuesday, bringing a trailing shortwave across the region. The trough moves offshore on Tuesday and the upper ridge likely rebuilds over the region by the middle of next week. A few lingering showers or thunderstorms will be possible across mainly the northern half of the region Saturday night, but do expect mainly dry conditions for all of the region on Sunday. The 12Z GFS shows 850 temps at around 17-19 C Sunday and with the upper ridge in control, fully expect a very warm to hot day. Temperatures Sunday likely climb into the upper 80s to lower 90s for much of the area. Low temperatures Sunday night will also be mild with reading in the upper 60s. Showers and thunderstorms may impact the region on Monday with the trough moving through the region. Very warm conditions continue into next week as the ridge rebuilds over the area, expect highs to generally range in mid to upper 80s and lows in the 60s. && .AVIATION /02Z THURSDAY THROUGH MONDAY/... As of 750 PM EDT Wednesday... High pressure slides off the coast through late tonight and Thursday bringing continued VFR conditions to the region. A weak cold front clips the DelMarVa late tonight into Thursday morning. This will bring some SCT-BKN mid-clouds, mainly from RIC-SBY, along with a very minimal chc of a shower (aob 20%) at SBY after 11z/early Thursday morning. The wind will be aob 10kt, with the direction shifting from NW to SW early this evening, then briefly becoming W or NW behind the front Thursday morning, before shifting back to SW by aftn. Outlook: Surface high pressure prevails off the Southeast coast Friday through Monday bringing VFR conditions. There is a minimal chc (20-30%) of showers/tstms late Friday aftn/evening and again late Saturday aftn/evening, mainly from RIC-SBY. && .MARINE... As of 345 PM EDT Wednesday... Afternoon sfc analysis shows high pressure centered over the Southeast US, with low pressure centered over wrn Quebec. The associated sfc trough extends SW into the Great Lakes. WV satellite shows an upper shortwave tracking NW toward the nrn Great Lakes. Winds over the bay/rivers are mainly W-SW at ~10 kt, but winds along the Atlantic coast are more variable. Seas are around 3 ft, while waves on the bay are 1-2 ft. The aforementioned shortwave/sfc low continue to track SE toward the Northeast US tonight as high pressure moves off the Southeast US coast. As this happens, the pressure gradient will tighten over the waters. Model consensus is forecasting winds to increase slightly tonight before peaking at just above 15 knots over most areas between 06-12z Thu. A few gusts to 20 kt are likely at the typical elevated sites late tonight. Seas will be in the 3-4 ft range tonight, while waves on the bay remain around 2 ft. The 12z/15 GFS (as well as the past few HRRR runs) show a 3-6 hour period of marginal SCA conditions over the Ches Bay. However, most of the other 12z models (including the WRF- ARW and WRF-NMM) do not suggest SCAs. Therefore, confidence in SCA conditions occurring is less than 50%, so will not issue any headlines with this forecast package. Winds become W-NW behind a weak boundary by late Thu AM. Winds turn more SSE by Thu evening and increase to ~10 kt. Winds become SSW then SW on Fri and increase to near 15 kt in spots as high pressure remains anchored off the Southeast coast and low pressure tracks through ern Canada. The trailing cold front may pass through the nrn waters early Sat AM. Regardless, sub-SCA conditions will prevail from Thu-Sat attm. && .TIDES/COASTAL FLOODING... As of 345 PM EDT Wednesday... Tidal anomalies in the Ches Bay have fallen to 0.5-0.8 ft in most areas. Water levels at Mobjack Bay and Bishop`s Head are forecast to crest right are forecast to crest right around minor flood thresholds during the upcoming high tide, but all other sites will remain below flood stage. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...None. && $$ SYNOPSIS...AJZ NEAR TERM...AJZ/MAM SHORT TERM...AJZ/ALB LONG TERM...AJB AVIATION...AJZ/MAM MARINE...ERI TIDES/COASTAL FLOODING...
Area Forecast Discussion
National Weather Service La Crosse WI
740 PM CDT Wed May 15 2019 .UPDATE... Issued at 737 PM CDT Wed May 15 2019 Atmospheric signals still look favorable for showers and some thunderstorms to make their way through the area around daybreak. This activity will be the continuation of the convection ongoing across North Dakota. The RAP continues to support the idea of the moisture axis currently along the Missouri river to shift eastward in strong warm advection. The 305K isentropic surface has a sharp gradient in specific humidity moving in and lifting, with some convergence as well. Most unstable CAPEs in latest RAP are in the 500-1000 J/Kg range /parcels lifted from the 750-850mb layer/, but lower values of wind shear will reduce the severe hail potential. CAMs have a pretty consistent message of a broken line of showers and some storms. Watching Thursday afternoon and evening carefully as well for severe storm potential. Latest model trends are moving the frontal boundary further south of the area. A limited window in the late afternoon /4-6pm?/ would exist per latest RAP solutions in the far southern /Grant-Clayton-Fayette/ counties in swrn WI and nern IA before the front slips south. However, the capping inversion may preclude convection altogether until evening. By this time, the storms would develop south of the area. The SPC slight risk of severe storms should shift south if the trend holds. && .SHORT TERM...(Tonight thru Thursday night) Issued at 220 PM CDT Wed May 15 2019 Main short-term fcst concerns are SHRA/TSRA chances late tonight/Thu morning and again late Thu afternoon/Thu night. 18z data analysis had a very weak frontal boundary dropping south across WI/southern MN as weak shortwave energy was dropping SE across the great lakes. Weak high building in behind the front. Boundary doing little more than pool some BL moisture for some cumulus across eastern WI to southern MN. With plenty of sunshine across the region today, mid-day temps around MN/IA/WI near to above normal for a change. Further west/north, low pressure/falling pressures were moving across the Dakotas, in response to a vigorous shortwave moving across southern Saskat. Model runs of 15.12z initialized well. Models in good agreement sliding the Saskat shortwave east into Ont tonight. Behind this feature W-NW flow aloft sets up over the region for Thu/Thu night, this on the east side of mid level ridge axis between a low over Hudson`s Bay and strong troughing digging into the central/southern Rockies. Short-term fcst confidence is on the good side this cycle. Quiet, seasonable spring weather continues this evening with dissipating diurnal cumulus and temps falling into the mid 50s to lower 60s. Shortwave passing north of Lk Superior late tonight/Thu morning drags a cold front to near KDLH-KMSP-KFSD by 12z Thu, then into/across the fcst area Thu. Main round of 850-700mb moisture/ moisture transport and lower level thermo-dynamic forcing progged to precede the front and move across the fcst area in roughly the 09- 15z time-frame. NAM/RAP model soundings show lifting of saturated 850-700mb parcels during this time results in 1200-2400 J/KG CAPE with little to no CIN. All high res/CAMs models now bringing a line of SHRA/TSRA into/across the fcst area 09-15z, well ahead of the sfc front. Have followed a CONs-short blend with a band of higher precip chances moving across the fcst area 09-15z. Once this convection exits, CAMs do little with the actual cold front as it slides across the area Thu. Some small SHRA/TSRA chances across the east/south parts of the fcst area Thu afternoon/evening near the cold front OK for now. Front begins to stall south of the area Thu night. 1K to 2K J/KG MUCAPE pool expected near/south of this boundary afternoon/ night, with an increasing push of moisture northward/over the boundary Thu night. An increase of SHRA/TSRA chances across the south portions of the fcst area Thu night is reasonable. Given the CAPE and an increase of 0-6KM shear, a few strong/severe TSRA would be possible Thu night. See SWODY2 for more details. With what may well end up to be a drier, partly cloudy/mostly sunny afternoon on Thu, blend of guidance highs well into the 70s even some lower 80s looks reasonable. After what is likely to be some morning rainfall and higher dew points around 60F, Thu afternoon may well end up feeling rather summery. .LONG TERM...(Friday through Wednesday) Issued at 220 PM CDT Wed May 15 2019 For Friday thru Saturday night: main fcst concerns are SHRA/TSRA chances and potential rain amounts thru the period with a warm front stuck in the area. 15.12z model runs in good agreement for shortwave ridging to slowly drift across the Upper Midwest this period, ahead of strong troughing slowly moving into the plains by Sat. Falling hgts Sat night as the troughing lifts toward the upper MS valley, but differences on how progressive the troughing is toward the end of this time period. Given the Fri-Sat night fcst depends on the position of a sfc-850mb warm front under shortwave ridging aloft, fcst confidence is average this period. Frontal boundary from late tonight thru Thu night to stall near I-80 by 12z Fri. As low pressure slowly comes east across plains and into IA by 12z Sun, the front remains nearly stationary or lifts slowly north as a warm front. As southerly flow ahead of the sfc-85mb low advects increasing moisture/CAPE northward, the front will be the focus for SHRA/TSRA development much of this period. Just where the front is any particular period will have a large impact on SHRA/TSRA chances across the fcst area. Greatest MUCAPE pool generally progged to remain south of the fcst area, as is the front, held/pushed back to the south at times by successive rounds of SHRA/TSRA. Greater model consistency for the front to be near I-80 Fri/Fri night with higher SHRA/TSRA chances mainly across the south half of the fcst area Fri/Fri evening quite reasonable. Cannot rule out some strong/ potential severe TSRA across the south end of the fcst area Fri afternoon/evening, however with area north of the sfc front, main threat would large hail, and the lightning. See SWODY3 for more details. More uncertainty with the sfc-850mb frontal position for Sat/Sat night owing in part to convection from Fri/Fri night and how quickly the shortwave trough lifts NE. Broader coverage of 40-80% SHRA/TSRA chances Sat/Sat night looking well trended for now. Potential exits for more strong/severe TSRA Sat afternoon/evening, but details of where and threats will depend on the frontal boundary. With what is looking to be plentiful cloud cover Fri/Sat, the blend of guidance highs below normal both days are reasonable. With PW values in the airmass over the area in the 1 to 1.25 inch range (1 to 2 std deviations above normal) much of this period, TSRA will be capable of producing locally heavy rains. This falling on soils still moist from recent rains, delayed green-up/evapo- transpiration increase and streams/rivers still running high/above normal. TSRA with locally heavy rains likely to eventually produce runoff and rises on area streams and rivers. Will once again have to monitor the heavy rain threat closely over the next few days. For Sunday thru Wednesday (days 4 to 7): main fcst concerns this period are continued SHRA/TSRA much of the period and potential for locally heavy rains. Medium range model runs of 15.00z/15.12z in reasonable agreement for a stronger short-wave trough/mid level low to lift thru the mid/ upper MS valley Sun/Sun night. This to be followed by some transient shortwave ridging Mon into Tue, then another shortwave/mid level low lifting into the Upper Midwest Tue night/Wed. As expected, plenty of shortwave timing/detail differences in the day 4-7 time-frame but fcst confidence average this cycle. Plenty of moisture/lift (PWs 1-2 std deviations above normal per NAEFS) to spread across the area Sun/Sun as a sfc-mid level low would be lifting NE across the region. 50-80% SHRA/TSRA chances Sunday, tapering off Sun night looking well trended. Concern will be TSRA capable of producing locally heavy rains on the heels of the potential heavy rains Thu night thru Sat night. By Sun, potential for much of the landscape to once again have saturated soils with heavy rains producing runoff and eventually more river rises. Transient shortwave ridging looking to provide a break from the more widespread precip Mon/Mon night. However next troughing/low into the plains Mon night, to lift NE toward/across the region, already looks to spread increasing moisture/lift and SHRA/TSRA chances back across the area Tue continuing into Wed. Will have to watch this one for the potential of more locally heavy rains. With what is looking to be plenty of cloud cover this period, the blend of guidance highs mostly in the 60s reasonable at this point. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 737 PM CDT Wed May 15 2019 VFR conditions overnight until a period of showers, and possibly thunderstorms, moves through the airfields in the 10-14Z time frame. This could disrupt morning flights however this would depend mainly on the intensity and coverage of the thunderstorms moving through. It does appear a broken line of storms will move through and this would warrant a brief TEMPO group of possibly IFR vsby for heavy rainfall. As confidence increases, the TAFs will be upgraded as needed. After this brief period, VFR is expected. && .HYDROLOGY... Issued at 220 PM CDT Wed May 15 2019 Attention is turning to the potential for a prolonged period of SHRA/TSRA chances starting late tonight/Thu morning continuing into Sunday night. With a rather moist airmass expected to be over the area, potential exists for most TSRA to be heavy rain producers. With soils still moist, locally heavy rains from mainly Friday through Sunday could result in runoff and eventual river rises. If repeated rounds of TSRA occur over a particular river basin, flooding could occur. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ UPDATE...Baumgardt SHORT TERM...RRS LONG TERM....RRS AVIATION...Baumgardt HYDROLOGY....RRS
Area Forecast Discussion
National Weather Service Bismarck ND
940 PM CDT Wed May 15 2019 .UPDATE... Issued at 940 PM CDT Wed May 15 2019 The severe threat is ending with the onset of boundary layer cooling and related increases in MLCIN. Otherwise, a surface cold front is crossing northwestern ND as of 02 UTC with significant surface pressure rises on the order of 3-5 mb/3 hour in its wake. This cold front will surge southeast overnight and will be through all of western and central ND by 12 UTC. Northwest surface winds in the wake of the front are stronger than anticipated by either the official forecast or model simulations to this point, so given observed trends and anticipated isallobaric responses to surface pressure rises we increased winds significantly overnight, with the highest speeds in northwest and north central ND where low- level lapse rates will be steepest during passage of the pressure rise bubble through about 06 UTC. Near-advisory speeds will occur along and north of Highway 2 the next few hours. Further south, low-level stability will be higher when the frontal passage takes place, but forecast soundings still suggest sufficient low-level mixing for breezy conditions. Finally, we also added a chance of showers to southwest ND after about 06 UTC in respect to the weakening convection upstream in southern MT, which appears to be associated with a weak shortwave impulse and related DCVA cresting the mean central U.S. 500 mb ridge. UPDATE Issued at 802 PM CDT Wed May 15 2019 Another quick update to clear Wells and Kidder Counties from the Severe Thunderstorm Watch since they are now behind the sustained convection/supercells that continue propagating east-southeast. UPDATE Issued at 704 PM CDT Wed May 15 2019 Quick update to clear additional counties -- including Morton and Burleigh and Bismarck/Mandan -- from the Severe Thunderstorm Watch in the wake of the shift to west-northwest winds. A severe threat continues downstream of the pair of discrete supercells centered on northern Stutsman and northeastern Emmons Counties as of 00 UTC. Storm coverage is likely to remain scattered in nature with weak background forcing, residual capping, and orientation of the deep-layer wind fields to the surface trough, as previously mentioned. Moreover, expect the severe threat to wane by mid evening as the boundary layer cools, resulting in increasing MLCIN, given the lack of richer low-level moisture. UPDATE Issued at 606 PM CDT Wed May 15 2019 The focus of this update was clearing western portions of the Severe Thunderstorm Watch in areas which are now behind the pre- frontal trough/wind shift. Severe-storm potential continues along and ahead of that feature in south central ND into the James River valley where surface dewpoints in the lower 50s F are contributing to 1000 to perhaps 1500 J/kg of MLCAPE. RAP analyses are slightly overestimating boundary layer moisture content compared to the observed trends, which may be contributing to a bit more residual capping and less bouyancy than objective analyses suggest. Still, effective shear magnitudes on the order of 40 kt are supportive of mesocyclones, and perpendicular orientation of deep-layer wind fields to the north-south-oriented surface trough along with the residual capping is resulting in a discrete mode. Thus, large hail up to golf ball size will likely be the most prominent hazard with isolated, high-based supercells the next few hours, followed by potential damaging winds. Large boundary layer theta-e deficits and associated MLLCL heights on the order of 1500 m AGL will keep the tornado threat negligible. UPDATE Issued at 358 PM CDT Wed May 15 2019 This update to include a severe thunderstorm watch in effect until 10 pm cdt for much of central North Dakota. The watch is along and east of a line from Velva and Towner in McHenry Garrison, New Salem, Elgin and Sioux County. This includes the Mandan and Bismarck areas, and the Jamestown area as well. && .SHORT TERM...(This evening through Thursday) Issued at 322 PM CDT Wed May 15 2019 Severe thunderstorm potential this afternoon and evening highlights the short term forecast. Currently, a north-south oriented surface trough extended from south central Saskatchewan to near Stanley to near Dickinson to near Hettinger. Strong and gusty southerly winds of 20 to 30 mph with gusts to 35-40 mph were ahead of the trough. Meanwhile a surface cold front extended from the Saskatchewan low southwestward across central Montana. An upper level shortwave associated with these features was moving east across south central Canada. An area of scattered to isolated showers/virga associated with the upper level shortwave continued moving east across north central North Dakota. We do expect thunderstorms to develop along/ahead of the surface trough as it tracks east across the state. Short term high resolution models have consistently depicted thunderstorm development to begin between 3pm-4pm in a line from near Dickinson/Hettinger to near Minot and Bottineau, then continue to develop as this line moves east. Most models show thunderstorms reaching Rugby/Bismarck-Mandan by 5pm-7pm, then near Jamestown/Ashley around 8pm-9pm and exiting the southern James Valley by around 10pm. We launched a weather balloon at 19z today...and it indicates at Bismarck there was a fairly good cap/inversion around 7000 feet elevation of 12.7C. We will need to wait until the surface trough for enough forcing to overcome this cap. Plenty of CAPE ahead of the trough (1000-2000 J/kg) as per SPC mesoanalysis. Models are indicating the thunderstorms mainly right along the trough, where forcing from low levels is greater. Effective bulk shear values of 40-45 knots over central North Dakota seen on SPC mesoscale analysis. Risk of severe storms extends from Minot to near Dickinson and eastward. Tonight a large area of cold air associated with a large Canadian high pressure system begins moving into North Dakota tonight behind the aforementioned cold front. On Thursday, cold air continues pushing into the state behind northerly and northeasterly winds as the southern extend of a large cool Canadian high pressure system extends across North Dakota into South Dakota. Much cooler Thursday with highs reaching only into the mid and upper 50s north to the upper 60s far southwest. .LONG TERM...(Thursday night through Wednesday) Issued at 322 PM CDT Wed May 15 2019 A significant pattern shift to below normal temperatures and above average precipitation highlights the extended forecast. The aforementioned large surface Canadian high pressure system remains entrenched across central Canada Thursday night through much of the weekend. Meanwhile, an upper level longwave trough over the west coast Thursday moves gradually eastward into the Rockies, expanding into the Plains Friday, with the first closed low of the system lifting northeastward into the Great Lakes by Monday. This scenario will bring cooler, cloudy weather to North Dakota, with widespread chances of rain showers. The best chances of widespread rain Friday looks to be western and southern ND, with the best day for widespread rain across our area on Saturday. Models are suggesting rainfall totals of 0.5" to 1.25" across western and central North Dakota Friday through Sunday night. Another closed low in the overall western longwave trough develops over the 4-corners area Monday, moving east into the central Plains Tuesday and lifting northward into the Dakotas/Minnesota Wednesday. This keeps the cooler, cloudy weather over North Dakota through mid- week. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 940 PM CDT Wed May 15 2019 A cold front will move southeast across the area overnight with a shift to northwest winds, which will gust to around 35 kt in the northwest and north central parts of ND, and which will be breezy at times late tonight in the south, as well. VFR conditions will generally prevail through Thursday afternoon, but there remains a chance of MVFR ceilings developing behind the cold front. If lower ceilings develop, they could impact KMOT, KJMS, and KMOT from late tonight into Thursday morning. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...CJS SHORT TERM...JV LONG TERM...JV AVIATION...CJS
National Weather Service Burlington VT
912 PM EDT Wed May 15 2019 .SYNOPSIS... After a few showers overnight, quieter weather returns on Thursday with clouds beginning to break during the afternoon hours. Another round of showers are on tap for Friday followed by near normal temperatures and drier weather over the weekend. The beginning of next week looks a bit unsettled with rainfall moving back into the region. && .NEAR TERM /THROUGH THURSDAY NIGHT/... As of 912 PM EDT Wednesday...Based off recent radar and observational trends, have cut back on PoPs considerably across the area for the remainder of the evening and overnight hours. This is in close agreement with latest HRRR output and only lower end chance values will be offered accordingly with additional QPF ranging from zero to a few hundredths as best forcing from shortwave passage has set up generally south and west of our area. The rest of the forecast remains on track with variably cloudy skies, light winds and low temperatures in the upper 30s to mid 40s. Have a great night. Prior discussion... Thursday looks to be another nice day across the region. In fact, it`s looking like temperatures will run 2 to 5 degrees warmer on Thursday than today with even more breaks in the afternoon hours. There may be some lingering showers at higher elevations as northwesterly flow aloft may help incite a few upslope showers across the Adirondack and Green Mountains. By the afternoon hours, mid-level heights will begin increasing which will help stabilize the atmosphere and bring an end to any additional upslope shower activity. Cloud cover will once again build back into the region Thursday night ahead of yet another shortwave taking aim at the North Country. && .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/... As of 314 PM EDT Wednesday...Light rain will continue to overspread the North Country Friday morning as a warm front moves through. Precipitation will turn more showery in nature during the afternoon as a cold front quickly follows. Total QPF from early Friday morning through early Friday night will generally be in the tenth to quarter inch range, with the highest amounts expected over the southern Greens and the Adirondacks, and the lower amounts expected further north towards the International Border. Although the forecast area will be within the warm sector of the system during the day Friday, cloud cover will prevent temperatures from reaching their full potential Friday afternoon. Highs will be in the upper 50s to lower 60s, although any areas that see breaks in clouds have the potential to overachieve on daytime highs. Precipitation will end Friday evening through early Friday night, followed by the arrival of drier, colder air air from the northwest. As subsidence builds overnight, mid- and upper-level clouds will quickly clear out. However, models continue to indicate some low-level moisture will linger through the night, trapped beneath a building subsidence inversion. This is especially true from the Champlain Valley eastward through Vermont, where low clouds will keep overnight lows in the low to mid 40s. Further west however, drier air will work into the lower levels, allowing temperatures to drop into the upper 30s/low 40s. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... As of 314 PM EDT Wednesday...Saturday looks to be dry at this point - a brief reprieve from the showery conditions that continue to dominate our weather. Highs will be in the low to mid 60s (still slightly below climatological norms). However, any lingering low clouds from early Saturday morning will quickly burn off, giving way to mainly sunny skies with just some high clouds moving in from the west. After a dry night Saturday night with lows again in the low to mid 40s, a warm front will move through Sunday and bring increasing chances for some spotty showers through the morning. There will likely be a break in precipitation sometime Sunday afternoon into Sunday evening as forcing wanes over the region. However, showers move back in Sunday night as another frontal system moves into the area. Monday through Tuesday will continue to feature unsettled weather as an upper-level trough slowly rotates through the northeastern U.S. Looking into the middle of next week, the upper-level pattern begins to amplify as ridging builds over the East Coast ahead of a deep trough digging into the Plains. Under this pattern, we could finally warm to at-or-above normal temperatures mid-week. However, despite the warmer temperatures, there aren`t any signs of a prolonged dry period in the forecast as the steering flow will continue to direct disturbances up and over the ridge and through the North Country. && .AVIATION /01Z THURSDAY THROUGH MONDAY/... Through 00Z Friday...VFR ceilings currently, with light showers in the area. Vicinity showers clear out earliest at KPBG and KBTV about 03Z, and latest at KSLK and KRUT about 15Z. Mainly VFR ceilings expected across KBTV, KPBG, and KMPV with the remaining terminals falling to 1500-3000ft agl ceilings beyond 03Z, and then lifting between 12Z-15Z. Visibilities generally unrestricted, but a few showers could bring KSLK to 4 to 6 SM at times until 04Z. Northwest to west-northwest winds of 5 kts will become light and terrain-driven tonight. Winds increase to 5 to 10 kts beyond 15Z with directions generally ranging southwest to northwest, with KPBG out of the northeast from lake influence. Outlook... Thursday Night: VFR. Chance SHRA. Friday: Mainly MVFR, with areas VFR possible. Chance RA, Chance SHRA. Friday Night: Mainly VFR, with local MVFR possible. Slight chance SHRA. Saturday: VFR. NO SIG WX. Saturday Night: VFR. Chance SHRA. Sunday: Mainly VFR, with local MVFR possible. Chance SHRA. Sunday Night: Mainly VFR, with areas MVFR possible. Chance SHRA. Monday: Mainly MVFR, with local IFR possible. Likely SHRA. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Clay NEAR TERM...Clay/JMG SHORT TERM...RSD LONG TERM...RSD AVIATION...Haynes
Area Forecast Discussion
National Weather Service Charleston SC
918 PM EDT Wed May 15 2019 .SYNOPSIS... High pressure will be the dominant weather feature into next week. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... Thicker mid-level cloud cover associated with an approaching shortwave is moving in quicker and is a bit more expansive than anticipated. Adjusted sky cover to reflect the latest RAP and GOES-E satellite trends. Also adjusted overnight lows slightly. The rest of the forecast is on track. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/... A warming trend is expected through the period with no mentionable chances for rainfall. A mid and upper level ridge will start the period centered to the west of the region, then gradually shift eastward over the area by late week/early weekend. At the surface, a ridge of high pressure will remain east over the Atlantic. This will result in low level southwest flow over the land, with a resultant sea breeze/southerly winds near the coast each afternoon. Model soundings and cross sections show only minimal moisture. Thus, have continued to keep PoPs below 15% through the period. Temperatures will continue to trend upward. High temperatures in the mid 80s inland and lower 80s closer to the coast on Thursday, then upper 80s to around 90 inland Friday and Saturday, except a little cooler near the coast. Lows in the lower to mid 60s Thursday night away from the coast, then mid to upper 60s Friday night. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... Deep layered high pressure will persist through early next week, providing continued quiet weather. Large scale subsidence will keep rain chances below 15%, however an isolated diurnally-driven shower is not out of the question. Temperatures will be several degrees above normal through the period. && .AVIATION /01Z THURSDAY THROUGH MONDAY/... VFR. Extended Aviation Outlook: VFR conditions expected to prevail into early next week at both KCHS and KSAV. && .MARINE... Tonight: High pressure will persist with generally light winds about 10 kt or less from the south/southeast. Seas mainly 2-3 ft, highest near the Gulf Stream. Thursday through Monday: High pressure is expected to remain centered just east of the waters through early next week. This will result in low level south- southwest winds. The pressure gradient increases a bit Thursday night through Friday, with sustained winds reaching closer to 15 knots, especially over the SC waters. Winds are expected to back to southerly near the coast each afternoon due to a resultant sea breeze. Otherwise, winds and seas generally 15 knots or less and sea 2 to 3 feet. && .TIDES/COASTAL FLOODING... Elevated tide cycles are expected through late week as astronomical influences increase from the upcoming full moon. Evening high tides could approach or exceed Coastal Flood Advisory levels along mainly the South Carolina coast through this weekend. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$
Area Forecast Discussion
National Weather Service State College PA
1026 PM EDT Wed May 15 2019 .SYNOPSIS... A weak cold front will drift south across the region overnight, and move off to the southeast tomorrow. Otherwise, the unseasonably cool weather pattern we`ve been in will gradually moderate through the weekend. Scattered showers will continue to threaten almost daily as a frontal boundary meanders north and south across Pennsylvania. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... A band of disorganized showers is moving through the Central Mountains as of 10PM. It`s troublesome that the HRRR doesn`t really see these showers, but they do look like they are fading as they move into a fairly dry airmass. The biggest question is what follows after midnight. The latest HRRR and the old HREF both bring additional showers down out of the Gr Lakes, but as yet there is not much rain upstream. At worst it seems shower coverage will be scattered for the most part as the rain traverses the region. Falling heights aloft and steepening lapse rates mean we cannot rule out a rumble of thunder. Right now the confidence is too low to include in the forecast however. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/... Thursday...a weak bubble of high pressure at the sfc and aloft will slide over the region and bring a mix of sun and clouds with similar high temps in the 60s to low 70s and slightly lower wind speeds. POPS will be minimal, but a brief stray shower is still possible across the high terrain over Northern PA. && .LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/... The weather pattern remains unsettled through Monday, with the most likely periods for rain on Friday and sometime early next week. However, scattered showers cannot be ruled out over the weekend. A stretch of dry weather is possible Tuesday into Wednesday. T-storms appear to target parts of western and southwestern PA late Thursday night through Friday. This area lies near a quasi stationary frontal zone and instability corridor extending from IA/IL through OH/WV. SPC D3 MRGL risk clips far southwest PA. There is still some uncertainty with how the boundary may influence temperatures over the weekend, but the general trend is warmer to the upside. An increase in humidity should also accompany the expanding warmth with dewpoints fcst to reach the 60s across south central PA. && .AVIATION /03Z THURSDAY THROUGH MONDAY/... A cold front moving SE across the NW Mtns and sweeping across the state will bring periods of bkn-ovc strato cu and some isolated to scattered -SHRA. Rainfall amounts will average a few to several hundredths of an inch of rainfall. Overall, expect VFR to dominate through Thursday. Winds will slacken as the inversion takes hold. As the inversion breaks around 15Z tomorrow the winds will be mainly from the West to NW at 8-12 kts with gusts into the Upper teens tomorrow. .Outlook... Thu...Early AM low cigs possible NW Mtns. Fri...No sig wx expected. Sat...AM low cigs possible N Mtns. Isolated PM tsra impacts possible. Sun...Periods of MVFR with the chance of showers. Mon && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...La Corte NEAR TERM...La Corte SHORT TERM...Lambert LONG TERM...Steinbugl AVIATION...Lambert/Ceru
Area Forecast Discussion
National Weather Service Des Moines IA
644 PM CDT Wed May 15 2019 ...Aviation Update... .DISCUSSION.../Tonight through Wednesday/ Issued at 339 PM CDT Wed May 15 2019 Synoptic Overview: Ridging over the Plains and Midwest will keep the weather quiet this afternoon. Short-wave trough over southern British Columbia and Alberta to move eastward which will increase activity Thursday and Friday across the Upper Midwest. Deeper trough currently out over the Pacific to make landfall along the western CONUS in the next 24- 36 hours. This will promote broad southwesterly flow toward the end of the week and through the weekend. Trough eventually becomes negatively tilted, which will lead to the potential for the ingredients to come together for active severe weather day(s) across the CWA through early next week. Today through Thursday Night: Ridge will continue to dominate for most of the day. Southerly surface flow will continue to promote WAA into the region, and the moisture content of the airmass will be on the rise. This will also bring in SBCAPE just under 1000 J/kg for most of Iowa and a little above 1000 J/kg MUCAPE, primarily in western Iowa into this evening. This could bring just enough lift through the area of 60 degree dewpoints to generate a few rain showers and isolated thunderstorms, primarily for western and northern Iowa. WSW 30 kt LLJ will kick in after Midnight tonight and continue into the early morning hours on Thursday. If rain showers have not utilized all the energy by early morning Thursday, new initiation going up with the LLJ present may result in a few stronger thunderstorms that produce hail and gusty winds. The overall threat of this is very conditional though, and of the CAMs the HRRR is really the only one favoring convection of any consequence as of this current forecast issuance. For the rest of the afternoon on Thursday, low-level flow remains southwesterly with healthy WAA into the region. This will continue to push temperatures into the upper 80s. Through the early afternoon hours on Thursday, POPs will remain relatively low but there is a non-zero chance for a rain shower or short lived thunderstorm. Then POPs increase later into the evening as the warm front develops and to drags across the area. Thursday Night, rapid height falls will start over the Plains which will aid in intensifying surface cyclogenesis over the High Plains. Surface trough will have a rather broad extent across the Plains into much of the Upper Midwest. In addition, airmass will become unstable across the CWA Thursday Night with 0-3km CAPE pushing 2000 J/kg. Lapse rates also look to be rather healthy ~7.5 K/km. Coupled with a 30-40 kt LLJ to introduce decent vertical wind shear, there is potential for a few strong to severe storms to develop and organize resulting in hail and gusty winds. Greatest chances right now look for this occur north of U.S. Highway 34. SPC has now included portions of central and northern Iowa in a slight risk with the 1730z D2 SWO. Friday: Trough will continue to push across the Front Range becoming negatively tilted. 12z guidance continues to favor surface cyclone deepening as it sits underneath an area of upper-level divergence. While favorable jet streak and associated ageostrophic motions remain more over the central Plains (central KS to central NE), warm front will continue sit over Iowa. This will provide a few things for severe weather potential on Friday, especially in western Iowa: First, warm-moist airmass continues to remain in place, and insolation will provide even more fuel for further instability (though questionable if it will be enough to break a cap). Secondly, the warm boundary could provide enough vorticity to aid in getting updrafts to develop rotation. However, there is some conflict amongst 12z guidance with this forecast issuance. This mainly is due to the placement of the warm front on Friday late into the afternoon. GFS/ECMWF keep the defined warm front further north, north of the U.S. Hwy. 20 corridor while the NAM allows the warm front to sag further south along the Interstate 80 corridor. For the severe weather environment, this is impacting where exactly the unstable airmass will lie. GFS/ECMWF favor bringing SBCAPE over 3500 J/kg further north than the NAM. Regardless of the positioning, there will be a lot of instability for thunderstorm potential on Friday (though must remain aware of the potential for a strong cap). The other factor will be a source of low-level vorticity available along the warm front. Overall though, effective bulk shear will not be hard to come by to aid organized convection. As the larger trough that is driving this pattern Friday and beyond comes ashore and is better sampled, guidance should provide a more consistent solution. By tomorrow afternoon, HREF and NCAR Ensemble may be able to help address some of the uncertainty with Friday`s forecast. Extended: Active weather pattern will continue throughout the weekend as trough continues to move eastward. GFS and ECMWF keep the trough negatively titled as it moves across upper Midwest. Beyond Friday it is difficult to point out exact threats from this weather pattern but severe weather is still very much possible. The extent of it will largely depend on what happens Friday with lingering cloud cover and how quickly the atmosphere would be able to recover. Regardless, it most certainly will be wet through much of the weekend with the large synoptic scale features in this weather pattern. Weak ridge develops by Monday which will provide a brief dry period but another trough comes ashore and by Tuesday brings active weather back to the area. Long term guidance depicts the potential for another potent low pressure system by the middle of next week. As is usually the case in the extended, timing and intensity differences between models is considerable at this point. More details regarding the activity on Tuesday will be known over the weekend. && .AVIATION.../For the 00Z TAFS through 00Z Thursday evening/ Issued at 635 PM CDT Wed May 15 2019 VFR conditions expected to continue through majority of the period. Potential for a overnight storms continues to exist, but confidence remains limited and have kept mentions out at this time. Timing would be after midnight for northwest, around 4am into central, and 7am for southeast. As storms show their hand in the Dakotas this evening, TAFs will be updated accordingly. && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION...Krull AVIATION...Curtis
Area Forecast Discussion...UPDATED
National Weather Service Grand Forks ND
1003 PM CDT Wed May 15 2019 .UPDATE... Issued at 1002 PM CDT Wed May 15 2019 Environment in the southern Red River Valley will remain favorable for isolated severe thunderstorms with potential for large hail and damaging wind gusts for the next hour or two due to the continued presence of strong effective shear coupled with weak elevated instability and dew points in the upper 40s to mid 50s. However, as storms move into northwest MN, stronger stability and very dry lower levels combine with weaker effective shear quasi- parallel with the line to yield a weakening complex of storms. Due to diminishing severe threat, will let watch expire. Overnight, rapid pressure rises and strong northwest winds behind the cold front will yield breezy to windy conditions with gusts up to 40 mph expected for early Thursday morning. This increase in winds is already developing across northwest ND so increased forecast winds to reflect this. UPDATE Issued at 704 PM CDT Wed May 15 2019 Environment across eastern ND remains favorable for discrete severe thunderstorms with effective bulk shear of 40-60 kts perpendicular to the line. Limiting factor over the RRV in the next few hours will be instability, which stronger (moderate) over the James River/DVL basin and drops off quickly toward the RRV. However, discrete supercells may be able to maintain strength into a more stable environment as sunlight remains for the next hour or two. Will be considering expanding watch slightly eastward to account for favorable shear, especially in northern valley. Storms in SC ND continue to progress into a favorable environment but will still have a few hours before tracking into far SE ND. && .SHORT TERM...(This evening through Thursday) Issued at 340 PM CDT Wed May 15 2019 Earlier this afternoon, an updated SPC SWODY1 Outlook has a Slight Risk for severe thunderstorms over most of central and eastern ND, to most of east-central into southeast ND, including the Fargo-Moorhead area, for the evening period. A Severe Thunderstorm Watch is now in effect until 10pm for a good portion of central ND, which includes much of the Devils Lake Basin, from Ramsey through Benson and Eddy Counties. While the 12z NAM12 and recent RAP hourly updates still favor a northcentral ND trigger area for mid to late afternoon... the HRRR models and HopWRF continue keying on potential late afternoon supercell formation along a BIS-JMS track...eventually spreading into southeast ND. As per previous discussions, the current surface dewpoints are quite dry eastern ND... with corridor of 50+ dewpoints limited to central ND attm. Boundary layer and mid level moisture advection will be keys to overall storm extent through the late afternoon and early evening. Blayer shear helicity seems quite viable so at least a few strong to severe supercells seems reasonable. During the evening and overnight periods, a stout low level jet should continue to provide some moisture convergence above any near surface stabilized areas, so that scattered elevated convection is expected to persist through the red River Valley and into northwest through west central MN... though overall severe threat will be quite limited. Following cold frontal passage overnight... moderate northerly blayer flow and steady subsident drying should produce mainly sunny skies but cooler conditions for Thursday. .LONG TERM...(Thursday night through Wednesday) Issued at 340 PM CDT Wed May 15 2019 An active pattern is the main story of the long term period with two round of precipitation expected. Friday through Sunday... A upper level trough is expected to move into the central part of the CONUS this weekend. This will lead to a wet period in the Northern Plains. Deterministic model guidance agrees on the general pattern, but still differs significantly on the details. The amounts of moisture that different model guidance brings up into eastern North Dakota and northern Minnesota differs with ECMWF being generally wetter and the GFS dryer. Regardless of these differences there remains a good chance of greater than an inch or rain in the southern Red River Valley. The greatest chances for over an inch have gone south now and the Fargo-Moorhead area may see less than previously thought. The main surface low will track southeast of the area leading wrap around precipitation to last into Sunday night. NAEFS and GEFS M-Climate continue to suggest that the greatest anomaly is to our south in South Dakota and southern Minnesota. So it is trending away from an anomalously high precipitable water and therefore high rainfall. Monday through Wednesday... Monday is looking like a dryer day with a possible break in the rain chances before another round of precipitation is expected to start on Tuesday. There is not a lot of certainty yet on this period as deterministic models become rather dispersive. There is a general signal though for an upper level low to approach the Northern Plains and provide support for another round of rain. Both the ECMWF and GFS both have a surface low approach the area, but have different timing and QPF with their different dynamics present in the upper levels of the atmosphere. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 625 PM CDT Wed May 15 2019 Just before 00z and ahead of a N-S cold front across central ND, a line of isolated strong to severe thunderstorms extends from Langdon to DVL to just SE of BIS. This line of SHRA and TSRA will move east into eastern ND this evening, affecting DVL around 00z then GFK, TVF, and FAR 03-06z with occasional MVFR cigs. Otherwise, low VFR conditions and wind gusts in the 20-30 kt range expected at TAF sites early this evening, along with scattered showers north of BJI, moving east into north central MN. On Thursday morning behind the front, winds will turn northerly and an area of MVFR cigs is expected to develop. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. && $$ UPDATE...BP SHORT TERM...Gust LONG TERM...NC AVIATION...BP
Area Forecast Discussion
National Weather Service Hastings NE
946 PM CDT Wed May 15 2019 .UPDATE... Issued at 942 PM CDT Wed May 15 2019 Made minor tweaks to tonight`s forecast, mainly to extend slgt chc POPs later into overnight and extend a little further E. There are two areas of ongoing convection W of the CWA: one near and SSW of MCK, and another from LBF to TIF. The S area is pretty disorganized, in an area of very weak shear, and has exhibited some warming cld tops over past hr. This area may limp into Furnas Co 04-06Z, and perhaps Phillips and Rooks counties as well, as it weakens. The northern area has a little more shear to work with, but even here, effective bulk shear is only around 25-30kt. Feel the last few runs of HRRR are too aggressive with tstm developmnt in the Sandhills overnight, but given still cooling cld tops to ongoing convection and incr low level jet, have trended the forecast towards at least some convection lingering later into the overnight. Think the main issue to watch will be gusty winds from dying convection as MCK recently recorded a 53mph gust shortly before 02Z behind a gust front and under weakening shwrs. Forecast soundings also support this with fairly dry atmosphere in lowest 3km or so. With that said, will maintain sub-severe wording in HWO from previous shift as think limited shear/upper support will limit organization. && .SHORT TERM...(This evening through Thursday night) Issued at 456 PM CDT Wed May 15 2019 Apologize for the late issuance, but there is A LOT of weather/potential weather going on over the next week as a whole and wanted to give it at least some "justice" content- wise... Focusing solely on these first 36 hours in this section, the 3 main forecast concerns and/or question marks include: 1) While the chances are low overall, and severe storms appear fairly unlikely, could at least a few/isolated storms sneak into mainly our western CWA this evening? 2) Just how warm/hot will Thursday get? Confidence is high that it will be the warmest day of 2019-so-far in most of our coverage area (CWA), and in fact Grand Island/Hastings could threaten record highs for May 16th (current records are Grand Island 92 in 1997/1939...Hastings 94 in 1927). 3) While most folks` severe storm attention is fixated on Friday, we can`t ignore a small chance of severe storms mainly in our northern CWA Thursday evening, where a Marginal Risk has been extended slightly southward compared to 12 hours ago. Taking a quick look at the current/recent weather scene as of 4PM: In the wake of a few rather-unexpected severe storms overnight in southern portions of our Nebraska zones, the vast majority of the daylight hours have been dry, sunny and seasonably-warm, with high temps on track to top out mainly 85-89, and perhaps our far southwest tagging 90. Dewpoints are still mainly in the 50s, keeping things from feeling overly-humid. In the big picture of the mid- upper levels, water vapor satellite and short- term model data reveal broad west- northwest flow overhead, with our region residing under broad ridging aloft, well-downstream from a large- scale trough centered off the Pacific Coast. At the surface, south- southeast winds have been a bit breezy this afternoon, with sustained speeds commonly 10-15 MPH/gusts 20-25 MPH. Now looking ahead forecast-wise through the next 3 forecast periods... This evening-tonight: Will admit right off the bat, confidence is slightly-shaky after seeing how last night played out. That being said, still feel that the vast majority of the CWA probably stays dry and storm-free, given an overall lack of forcing aloft and the fact that low-mid level convergence is weaker than last night. That being said, have opted to maintain a slight chance (20 percent) of thunderstorms mainly within the western 1/3 of the CWA this evening (mainly 9 PM-1 AM), just in case some of the activity getting underway well to our west manages to eventually drift into our domain. Models such as the HRRR depict this possibility, but it seems over- aggressive too. There is perhaps also a non-zero chance for a few showers/storms to pop up near our far northeast edge this evening as well (as suggested by the GFS), but this seem more like a 10 percent chance, and thus is not in the official forecast at this time. Any storms that might affect our CWA tonight are not expected to be severe, but as evidenced last night, we are getting into that time of year when occasional "surprises" can happen. Otherwise tonight, breezes will average 5-15 MPH, with direction generally shifting from more southeasterly to more southwesterly with time. Low temps look to be similar to last night, mainly upper 50s-low 60s. Thursday daytime (through around 7 PM): Have maintained a dry forecast, as the main story through the day looks to be the overall-hottest day of 2019-so-far. Winds will again prevail southerly, and will be fairly breezy in southern/southeast zones with gusts of 20-30 MPH likely, while especially northwest zones will see lighter speeds (mainly sustained 5-15 MPH with less gustiness). During the afternoon, a weak cold front will slip southward through northern Nebraska, likely barely entering our far northern zones (Ord area) by late afternoon/early evening, and its presence marked by light easterly breezes. If anything, nudged up high temps 1-2 degrees, with most areas expected to top out 91-95 (although the far north would end up cooler if the front sags in faster/farther south than expected). Dewpoints should prevail in the 50s again during the afternoon, keeping humidity/heat index values in check. Thursday evening-night (after 7 PM): Although only 24-36 hours away, the "exact details" of storm development still contain some question marks. To make a long story short though, at least slight chances for storms have been expanded a bit farther south than previous forecast, but still mainly focused within the northern 1/4 and western 1/4 of the CWA, in closest proximity to subtle disturbances moving in from the southwest, and also the aforementioned frontal boundary draped across our northern CWA. Agree with SPC in extending the formal Marginal Risk down to around I-80, but storm coverage in our CWA could be fairly minimal, with the majority of "action" focused at least slightly to our north. Could be a close call either way. Main threat with any severe storms looks to be hail to around golf ball size/wind gusts to around 60 MPH. While the main threat of any severe should wane by midnight or so, would not be surprised to see at least isolated/rogue activity continue through the night, perhaps even south of I-80 where the official forecast is currently dry. Low temps are aimed quite mild by mid-May standards, with most areas holding up in the mid-upper 60s, but as cool as near-60 far north and west-central. .LONG TERM...(Friday daytime through Wednesday) Issued at 456 PM CDT Wed May 15 2019 General overview of this 6-day period: 1) While the main focus of this entire time frame for most reading this is probably on the currently Enhanced Risk (category 3 of 5) of severe storms for Friday afternoon-evening, will admit right up front that with this still being 48 hours away, this discussion will not go into much detail on the "finer details". Per our latest Hazardous Weather Outlook (HWOGID), there is a real possibility that at least a few storms mainly in the northwest 1/2 of our CWA could produce very large hail to around baseball size, damaging winds and maybe even a few tornadoes, but this is far from looking like a classic "tornado outbreak" setup as well. It`s getting closer, but we`re gonna have to wait another 24+ hours to really get a handle on the finer mesoscale details that could "make or break" this from being a fairly "standard" severe weather event versus a "higher end" one. See below for a bit more. 2) Assuming timing of upper air/surface features does not start slowing between now and then, the severe storm risk for Saturday (which once looked fairly favorable for our CWA) continues to decrease, with the main instability axis now expected to focus at least slightly to our east-through-southeast by afternoon peak heating. That being said, will still need to watch our far east- southeast zones for at least a few strong storms, especially if timing of the main cold front does slow a bit. 3) With so much attention on severe storm possibilities Thursday- Saturday, it`s hardly worth even going into possible severe storm risks for next week. Compared to a few days ago, however, most days next week have trended cooler (in some cases notably so), thus in theory diminishing any severe storm threat that once looked more favorable for days such as Monday. That being said, it is May after all, and for example the latest ECMWF would suggest that a day such as Tuesday may need watched for a sneaky "cold core" type severe setup, despite somewhat cooler temps. A TON of uncertainty here. 4) No matter how severe (or not) storms over the next week are, there are plenty of rain chances in the forecast on several days/night. Cumulative 7-day rainfall expectations (including the short term periods) are currently expected to range from 1.50-2.50" across most of the CWA as a GENERAL average, with localized higher amounts certainly likely. In other words, an overall wet-week forthcoming. With the main points covered, will finish with some rather brief day-to-day comments... Friday-Fri night: Clearly our main focus for severe storm potential, especially in our western/northern zones thanks to a potent combo of mixed-layer CAPE generally around 3000 J/kg and deep layer shear of 30-40 knots and increasing low-level shear with time. Latest NAMNest clearly suggests a few supercells could track from southwest-to- northeast across parts of our CWA late afternoon-evening, with perhaps more of a linear severe threat overnight as the cold front pushes in. Cannot rule out a tornado risk, but large hail perhaps up to around baseball size should be the MAIN threat. High temps mainly mid-upper 80s. Sat-Sat night: As mentioned, the severe threat continues trending down, but bears watching especially far east-southeast. Cooling trend underway with highs mainly 70s. Sunday-Sunday night: Despite rain chances in the latest forecast, the vast majority of this 24 hours is looking rather dry, as we reside "in between" systems. Cooler still with highs only in the low-mid 60s for most. Monday-Tuesday: The next strong/large-scale trough approaches and moves in, giving us several rain chances. Severe storm threat perhaps tempered by cooler temps, as both days have trended down at least 4-6 degrees from previous forecast, with highs mainly only 60s. Wednesday: Very preliminarily, this looks like a mostly dry day with temps rebounding to around 70. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Thursday) Issued at 643 PM CDT Wed May 15 2019 Significant wx: Low level wind shear tonight. Tonight: VFR. May see some weakening convection arrive from the W in the 04Z to 06Z time frame. Confidence is too low to go anything other than VCTS at this time for EAR, with weaker VCSH for GRI. A 45-50kt low level jet atop sfc winds around 10kt should result in low-level wind shear at both terminals from around 06Z to 12Z. Confidence: Medium. Thursday: VFR. Quiet aviation conditions expected with only sparse high clds expected along with Srly sfc winds around 10-12kt. Confidence: High. && .GID WATCHES/WARNINGS/ADVISORIES... NE...None. KS...None. && $$ UPDATE...Thies SHORT TERM...Pfannkuch LONG TERM...Pfannkuch AVIATION...Thies
Area Forecast Discussion
National Weather Service North Platte NE
633 PM CDT Wed May 15 2019 .SYNOPSIS... Issued at 318 PM CDT Wed May 15 2019 H5 analysis this morning had a broad ridge of high pressure extending from eastern New Mexico, north into south central Canada. Downstream of this feature, a closed low was located over southern Maine with a trough of low pressure extending south toward Bermuda. West of the ridge, a deep trough of low pressure extended from the Gulf of Alaska south into the eastern Pacific. Highly amplified flow was noted along the west coast of the CONUS this morning with south southwest to north northeast flow extending from central California north into eastern Washington. Within this flow, a nice shortwave was noted over northwestern Montana with a second shortwave noted over southern Idaho. Across the Central Plains this morning, a shortwave was located over sern Nebraska. This was the remnants of convection which tracked through portions of western and north central Nebraska overnight. Current WV imagery has another weak shortwave over central into eastern Wyoming. At the surface, A warm front extended from sern Montana into western South Dakota then central Nebraska. East of this feature, winds were easterly and southeasterly, while west of the front, winds had a westerly component and were generally from the south or south southwest. Skies were mainly clear this afternoon and 2 PM CDT temperatures were in the lower to middle 80s. && .SHORT TERM...(This evening through Thursday night) Issued at 318 PM CDT Wed May 15 2019 Thunderstorm chances will be the main forecast challenge in the short term, followed by temperatures Thursday. For tonight: The weak upper level disturbance, currently over eastern Wyoming, will approach the panhandle early this evening. Steep lapse rates will be in place across the panhandle and western Sandhills with a well mixed environment. Isolated thunderstorms will track east of the panhandle this evening and are not expected to make it into eastern portions of the forecast area overnight. This is supported by the latest HRRR and 4KM NAM solns which end precipitation by late evening. For Thursday: Ongoing thunderstorms across the eastern Dakotas into Minnesota, will force a weak back door cool front into northern portions of the forecast area Thursday morning. This quasi-stationary boundary will then stall across northern portions of the forecast area by mid afternoon Thursday. North of the front, highs will reach the lower to middle 80s, while south of the front, highs will reach the 90s, with some middle 90s possible across the far southwestern forecast area. There were some fire weather concerns for Thursday afternoon earlier in the week, given the expected minimum RH around 15 percent. Low pressure will be anchored over nern Colorado into swrn Nebraska with a dryline extending from the low into western Kansas. INVOF The dryline/sfc low, sfc winds will be light tomorrow afternoon, so the threat for strong winds is minimal attm which will limit any critical fire weather threat. By Thursday night, the west coast trough will transition through the Sierra Nevada range, emerging onto the high desert of Nevada. A lead disturbance will lift from Colorado into western Nebraska Thursday evening. Initially, the CAP will remain strong through the afternoon hours, with weakening noted around 00z Friday. Thunderstorms should initiate off the higher terrain of nern Colorado lifting into western Nebraska during the evening hours. ATTM, am not very concerned about initiation along the dryline Thursday afternoon/evening as the cap is strong and temps aloft warm. With this in mind, will paint the highest pops across the west and in the north INVOF the frontal boundary. As for the severe threat, wind shear is favorable, for large hail and damaging winds. There will be a minor tornado threat, however INVOF the front, with backed low level winds. However, with the bulk of convection along the front not anticipated until evening, thinking the tornado threat may be fairly minimal given the expected timing along the front. .LONG TERM...(Friday through Wednesday) Issued at 318 PM CDT Wed May 15 2019 An active weather pattern will continue into the extended periods beginning on Friday. A good setup exists Friday afternoon for severe storms across a large chunk of western and north central Nebraska. The location will be highly dependent on where the cold front and dryline set up Friday afternoon. Based on the latest forecast model trends, the cold front will make it just about to Interstate 80 Friday afternoon. A dry line will become anchored from the front, south across western Lincoln into Hayes County. By 21z Friday afternoon, the cap appears to be completely eroded, so initiation appears to be in the 4-6PM CDT time frame and basically just to the west of North Platte. As this convection lifts north into the cool front where low level helicities are maximized, there is the threat for tornadoes. The initial severe threat however, will be very large hail given the very steep mid level lapse rates and forecast CAPE north of 3500 J/KG. One word of caution here: Where the front/dryline will set up on Friday is still yet to be determined and thunderstorms Thursday night will weigh heavily on the location of greatest threat for severe storms Friday. Persons should closely monitor the latest forecasts and severe outlooks as the location of greatest threat could change. After Friday, a fairly active pattern will continue across the central CONUS as a broad trough of low pressure remains entrenched across the intermountain west. The severe threat however, should remain east of the area with the warmer temps and better moisture. Temperatures will be below normal during the remainder of the forecast period with wetter than normal conditions expected. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 622 PM CDT Wed May 15 2019 VFR conditions over the next 24 hours, however isolated thunderstorms possible this evening through the overnight. Have left the mention of thunderstorms out of the TAF as confidence is low in any thunderstorms making it into KVTN or KLBF areas but an isolated chance is still possible. Winds will shift from the south southwest this evening to the northeast by Thursday morning. Winds will shift again across southwest Nebraska late afternoon to the east southeast. There is another chance of thunderstorms Thursday late afternoon into the evening, however the best chance for scattered thunderstorm development across north central and southwest Nebraska at this time appears to be in the evening hours, outside of the 24 hour period. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Buttler SHORT TERM...Buttler LONG TERM...Buttler AVIATION...Gomez
Area Forecast Discussion...CORRECTED
National Weather Service Chicago/Romeoville, IL
717 PM CDT Wed May 15 2019 .SHORT TERM... 254 PM CDT Through Thursday night... Looks like a fairly complicated weather scenario will occur across our region on Thursday, with subtle mesoscale features playing a pivotal role in the temporal and spatial evolution of our convective chances. A threat for strong to severe thunderstorms exists, primarily late Thursday afternoon and into the evening hours followed by a threat for some flash flooding on a localized basis Thursday night and into Friday morning. For the remainder of the day all looks to stay quiet. We`ve managed to mix into some moisture just off the deck and the result has been a splotchy cumulus field. Vertical development remains limited across our region, with a few radar echoes appearing within a more develop Cu field across southern/central Wisconsin within an axis of slightly greater mid-level moisture. Looks like any precipitation chances across our CWA will remain under 5-10% through the rest of the afternoon hours. A weak lake breeze has pushed inland which will keep the immediate lake shore areas in the upper 50s and lower 60s, while low to mid 70s prevail inland. Our main disturbance of interest is currently translating across northern Montana and into North Dakota as a notable darkening in GOES16 mid-level water vapor loops. This shortwave will begin to ignite showers and storms across the Upper Midwest through the evening hours and this activity is expected to track south and eastward overnight. Around daybreak on Thursday a complex of showers and storms should be diving into central and southern Wisconsin. What happens from there remains a bit unclear. While an expansive EML plume will be gradually pivoting overhead through Thursday morning, incrementally steepening mid-level lapse rates overhead, forecast soundings across northern Illinois through the mid-late morning hours don`t appear all that favorable for the maintenance of a robust area of convection as 925-850 mb flow quickly veers and weakens. This combined with still limited overall instability casts a good deal of doubt on the more aggressive CAM solutions. Still, with plenty of members of the NCAR Ensemble and a few from this morning`s HREF indicating storms holding together down towards the I- 88 corridor, have painted some low PoPs and thunder chances across the northern half of the CWA through the morning hours as a result. Don`t currently expect much in the way of a severe threat with this activity, but the fact that the 18z HRRR continues to show some robust updrafts is a bit concerning. Could certainly be some gusty winds exhausted by the decaying complex as well as some small hail with this morning activity. In addition, as some additional moisture is pumped northward overnight, there`s a potential that some patchy fog develops mainly east and south of I-57. Instability will build quickly through the daytime hours on Thursday as the aforementioned EML plume--characterized by extremely steep 8 to 8.5 C/km lapse rates in the 800-600 mb layer--advects overhead. Combined with heating and dewpoints increasing into the mid and upper 60s, MLCAPE values will probably approach 1500-2500 J/kg during the afternoon and early evening. Forecast soundings still appear capped through the afternoon hours with +14 to +15 C air at 750 mb. However, guidance remains in pretty good agreement that the combination of heating, moistening of the boundary layer, and increasing surface convergence with the approach of a cold front will be sufficient to ignite additional showers and thunderstorms during the late afternoon and early evening hours. Effective deep layer shear values around 30-35 kts would support supercells and with such high CAPE present in the hail growth zone and extremely steep mid-level lapse rates, large hail may be the initial primary threat (perhaps to the size of golfballs or slightly larger with the strongest updrafts based on SHIP values pushing 1.5-2. Where this initial convective development takes place remains uncertain, as it`s conceivable the previously-mentioned morning complex lays down an outflow boundary that could focus activity farther south than currently advertised. At this juncture, it looks like the most favored area for robust storm development would initially take place near and north of the I-88 corridor with activity quickly congealing into a line and sagging southward through the evening and overnight hours. As this occurs, the severe threat may transition to more of a strong and gusty wind scenario as activity gradually diminishes in intensity. Overall think the tornado threat appears low given /1/ limited potential for near-surface inflow parcels into the evening hours as the boundary layer begins to decouple and /2/ fairly weak low-level wind fields. The primary weather threat may start to transition mainly to locally heavy rainfall through the late evening and overnight hours as upwind Corfidi Vectors orienting parallel to the initiating frontal boundary and decreasing to 10 kts or less. We`d be a bit more concerned about a higher-magnitude flash flood threat if the low- level flow were a bit higher as this pattern loosely resembles a Maddox frontal flash flood set up. Extended hi-res guidance continues to suggest there may be just enough of a tendency for convection to form a migratory cold pool to keep the threat for widespread flash flooding lower as convectively-reinforced outflow continually sags southward through the overnight hours. Still, the potential exists for pockets of 2"+ of rainfall into Friday morning which could certainly result in some isolated instances of flash flooding. Carlaw && .LONG TERM... 326 PM CDT Friday through Wednesday... Period continuing to look active with several periods of likely shower and thunderstorm development. This begins at the start of the period on Friday, with additional showers/thunderstorms likely. Boundary which will move through the area late Thursday night into Friday will continue to sag south during the day on Friday, and likely setup somewhere across central/east central IL into central IN. Cooler conditions are expected north of this boundary, over much of the CWA, on Friday. However, persistent southerly low/mid level flow will continue to usher in elevated instability overhead. Guidance indicating that upstream mid level energy will ride mid/upper level ridge towards the area Thursday night into Friday. This focus, right along the boundary, should help to develop additional storms, which will likely move east towards the CWA during the day Friday. Will need to monitor the potential for additional rainfall, as well as at least some isolated stronger storms. Surface based instability will likely be limited north of this boundary, but there will likely be enough elevated instability to support some stronger thunderstorm development and a hail risk. Focus for thunderstorm development should begin to drift to the north into Wisconsin Friday night, as the ridge continues to build across the region. By Saturday morning, surface boundary will be trying to lift north with some guidance showing this boundary moving well into Wisconsin by Saturday morning. I do wonder if this is a bit aggressive, and think the front may hang up somewhere across northern IL during the day Saturday. With either scenario, drier conditions are appearing probable Saturday morning. This changes by Saturday afternoon into the evening when thunderstorm chances increase once again. If this boundary does indeed hang up across northern IL, then additional focus for more organized thunderstorm development will be present along with focus for additional heavy rainfall Saturday night. The highly amplified pattern is expected to usher in a deep and negatively tilted upper level trough and deepening surface low on Sunday, with widespread thunderstorm chances returning to the area. Another period to monitor for additional rainfall and the threat of severe weather, given the strength of this system. Maybe a little bit of a lull in the activity on Monday, but expect thunderstorm chances to increase once again Tuesday into Wednesday as the pattern will remain highly active. This will be another period to monitor for additional strong/severe thunderstorm potential. Rodriguez && .AVIATION... For the 00Z TAFs... The lake breeze developed as expected this afternoon and made it through MDW but never got to ORD. It now has started retreating so winds that did turn east should go back to a southwesterly direction, perhaps with a southerly component for a while. After quiet conditions overnight, winds increase from a southwesterly direction tomorrow and usher increased moisture into the area. This will begin to support multiple periods of showers and thunderstorms...with timing somewhat uncertain. The first round appears to move through around mid to late morning but could be in a dissipating stage, so thunder is emphasized more toward RFD and showers are mentioned at the other terminals. Toward evening the first of several additional rounds of storms starts to approach the area. These could persist for most of Thursday night, off and on. One wildcard is how widespread the daytime round of activity may end up being. If it ends up being more potent than presently expected, this could produce considerable impacts during the day and hinder or slow the later development, whereas presently the more significant activity is expected to arrive in the evening. The evening is also the period of concern for hail and strong winds, with heavy rain an additional possibility if multiple rounds of storms track across the same location repeatedly. Lenning && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...None. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSCHICAGO WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion
National Weather Service Melbourne FL
808 PM EDT Wed May 15 2019 .UPDATE... Weather conditions have settled for east central FL late this afternoon with the only presence of clouds streaming across the area. From Orange to Lake and Volusia, water vapor depicts dry air over them while low and high clouds are still from Osceola to Martin counties. Local Doppler radars are not showing any precipitation over our forecast area even though HRRR is showing some shower development to the east of Lake in the next few hours. A slight chance for showers was kept for Lake and cleared for the rest of the counties except for Treasure Coast and Okeechobee due to a slight presence of moisture over the area that could trigger a light shower this evening. However, chances will come down after midnight, with partly cloudy expected for the second part of the night. No other changes were made to the forecast. && .AVIATION... VFR conditions expected through the night and on Thursday with light easterly winds. Isolated development of showers can be possible for KFPR-KSUA in the afternoon. && .MARINE... East light to gentle breezes will prevail overnight across the east central Atlantic waters with seas 2 to 3 feet. && .MLB WATCHES/WARNINGS/ADVISORIES... FL...None. AM...None. && $$ Negron/Weitlich