Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/25/17

Area Forecast Discussion
National Weather Service State College PA
1026 PM EDT Thu Aug 24 2017 .SYNOPSIS... A large area of Canadian high pressure will build southeast and bring us a several day string of mainly dry and comfortably cool weather with low humidity right into early next week. The lone exception to these dry conditions will be late this afternoon through the first half of tonight. Scattered showers will develop this afternoon across the Alleghenies of northern and western Pennsylvania, and last into early tonight across much of central and northwestern pennsylvania as a potent upper disturbance, represented by colder than normal air aloft passes overhead. && .NEAR TERM /THROUGH FRIDAY/... Adjusted POPS up some, mainly to the east. Showers holding together, given cold air aloft and rather strong dynamics. Earlier discussion below. Mid afternoon visible imagery shows heating of the higher terrain of northern and western PA helping to expand a dual bkn-ovc layer of cu and higher based strato/altocu. As temps aloft gradually cool isolated to scattered -shra are expected in the 21Z Thu through 04Z Friday period as far SE as a KMRB to KSEG and KAVP line. The primary feature that we`re focusing on that will help to focus afternoon and evening convection and greatest concentration of bkn-ovc ceilings will be a distinct NW/SE tongue of higher theta-e air at 850-700 mb that was wrapping around a low-mid level mesoscale trough across Eastern Ohio, and extended from near KPBZ to KLBE and KCBE at 1830Z. Latest RAP and HRRR continues to show the highest Sfc based cape of a few to svrl hundred J/kg of cape in this area and some light qpf-locally 1-2 tenths of rainfall from an organized area of light to moderate showers and possibly a few low-topped tsra as the left exit region of an 80 kt 300 mb jetlet approaches from central/southern Ohio. The relatively cold cloud tops could lead to some small hail pellets in the possible/taller storms - especially across Cambria and Somerset counties. Collaborated with WFOs LWX and PBZ to raise previous chc pops to likely and even categorical late today through 04Z Friday across our southwest zones near KJST/KAOO...with high chc-low likely in the band from near KBFD to KUNV and just west of KTHV. Little more than some sprinkles or perhaps a brief shower should fall east of a KMDT to KIPT line. Current temps in the mid-upper 60s across the northern and western mtns, and mainly low to mid 70s in the central and southern valleys are within a deg F or two either side of forecast highs, and are about 5 to 10F below normal over most of the area. Areas of bkn strato cu and alto cu lingering into the early-mid morning hours Friday as another upper trough arrives will keep temps tonight a few to several deg F milder than last night. Some clearing before daybreak across the NW mtns combine with very light winds and a large air/water delta T will support areas of 1/2-2SM valley fog across northern PA. && .SHORT TERM /FRIDAY NIGHT THROUGH 6 PM FRIDAY/... Friday may start out mostly cloudy in the east as the aforementioned second upper vort max crosses that region. However, clearing will spread in from the west and the remainder of the CWA should see just scattered clouds through much of the day as high pressure builds in. There could be a few short periods of bkn high based cu/strato cu across the nrn and western mtns in the afternoon as anomalously cool air aloft lingers over the state. Max temps on Fri will be very similar to today (Thursday). && .LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/... An extended period of refreshingly cool, pleasant and dry weather will continue through the upcoming weekend as high pressure remains in control of the weather pattern over the northeast quarter of the CONUS. It will feel more like early fall than late summer. A few spots in north-central PA could see morning lows dip into the upper 30s over the weekend. Global models suggest isolated, terrain-induced convection may be possible within return flow along the spine of the central Appalachians over the weekend. However, ensemble means favor a continuation of the mainly dry and seasonably cool pattern through early next week, as upper level ridging out West the supports mean troughing downstream over the Northeast. Recent medium range model and ensemble runs depict a more unsettled pattern developing by the end of the month. An upper level low is projected to drop into the OH Valley, with a frontal boundary and plume of deep moisture situated off the Southeast coast. Latest NHC 5-day outlook has increased the probability of tropical/subtropical cyclone formation to 40% with a trough of low pressure currently near the Florida peninsula - projected to drift north-northeast over the western Atlantic and merge with the aforementioned frontal zone. The enhanced moisture return/influx ahead of the upper low may favor an increase in POPs late in the period. For now, model guidance keeps the remnants of Harvey over the Lower MS Valley to start the month of September. Beyond that, will need to monitor the system as it should begin to lift northeast but it`s still way to early to speculate on any potential impacts. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... Showers continue to stream through central PA this evening. The highest concentration of showers at 01Z is along the southern half. As such have included TEMPO groups at JST and AOO between 00Z to 02Z. Latest HRRR shows these showers should continue through the first half of the overnight periods. With decent instability provided by the approaching trough and moist unstable air through the low levels, these showers should continue as they move to the east. Weak flow through the low and mid levels will keep these showers slow moving. As there is a cap aloft along with dry air, am not to concerned with thunder. As these showers move to the east along with dropping temperatures MVFR cigs and vsbys at MDT and LNS are possible. As such have added TEMPO groups and restrictions accordingly. These showers should move through between 06Z to 09Z. The cloudiness overnight could preclude the return of any fog overnight though it should return to the usual valley locations up north late tonight through shortly after sunrise Friday, as some clearing occurs with light wind and very cool temps with large air/water temp spreads. Any borderline MVFR strato cu early Friday across the eastern half of the state will improve to SCT-bkn035-050 by late morning. .OUTLOOK... Fri-Tue...Patchy AM fog possible, mainly across northern Pa. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Lambert NEAR TERM...Lambert/Martin SHORT TERM...Lambert LONG TERM...Steinbugl AVIATION...Lambert/Ceru
Area Forecast Discussion
National Weather Service Cheyenne WY
933 PM MDT Thu Aug 24 2017 .UPDATE... Issued at 933 PM MDT Thu Aug 24 2017 A quick update to the forecast this evening to refine late evening precip chances based on current trends. Latest radar images show the only area of convection that remains is near the Torrington and Scottsbluff areas. HRRR output shows convection lingering until 3 AM for areas in the Panhandle, so have adjusted precipitation accordingly. No additional changes were necessary. && .SHORT TERM...(This evening through Saturday) Issued at 307 PM MDT Thu Aug 24 2017 Some showers and a few storms noted over parts of the CWA early this afternoon, most concentrated over Kimball county and the Snowy range area. Movement is generally east rather slowly. Expect this to persist into this evening over these area with other activity expected to develop over east-central Wy into the Panhandle as a weak impulse nears the area. Convection may persist into the night over parts of the Panhandle as some WAA develops so have kept some pops going in that area. Good instability exists but shear weak so a few stronger storms possible for brief periods of time into this evening. No significant changes seen Friday through Saturday with warm afternoons both days. An upper high will build over the 4 corners region Friday and hold into the weekend. Mainly dry Friday with less instability seen though a bit of convection may develop as another weak impulse traverses the area. Better instability should return to mainly the Panhandle Saturday as some lee troughing develops and allows for some moisture return and another weak impulse drops southeast over the high plains at that time. .LONG TERM...(Saturday night through Thursday) Issued at 307 PM MDT Thu Aug 24 2017 Convection in the Nebraska Panhandle should quickly dissipate going into Saturday evening, then we will probably see a fairly extended dry pattern through midweek next week as upper ridging builds in from the southwest pushing the shortwave track north of our area with dry northwesterly flow pushing down across eastern Wyoming and western Nebraska. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 638 PM MDT Thu Aug 24 2017 Only concern to aviation ops tonight will be evening convection. Coverage has been very limited across the region, so expect little if any impact. That said did include VCTS at KCYS, KAIA, KSNY, and a TEMPO TS group at KCDR. Although these storms will be possible over the next few hours, expect them to dissipate by 03z or so. Otherwise, expect VFR conditions overnight. && .FIRE WEATHER... Issued at 307 PM MDT Thu Aug 24 2017 Mainly dry and warm weather will be over the area through the weekend with high pressure in the upper atmosphere being the main controlling factor. Some isolated convection possible from time to time mainly around the mtns but other weather factors expected to be non-critical. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ UPDATE...CAH SHORT TERM...RE LONG TERM...JG AVIATION...CAH FIRE WEATHER...RE
Area Forecast Discussion
National Weather Service Green Bay WI
1044 PM CDT Thu Aug 24 2017 Updated aviation portion for 06Z TAF issuance .SHORT TERM...Tonight and Friday Issued at 240 PM CDT Thu Aug 24 2017 The latest RAP analysis and satellite/radar imagery show high pressure stretching from northwest Ontario to the western Great Lakes early this afternoon. Behind a departing shortwave, diurnal cu popped up by late morning over eastern WI aided by weak moisture fluxes off Lake Michigan and Green Bay. Though return flow continues over the Plains, forecast concerns revolve around temps tonight as high pressure remains over the area. Tonight and Friday...High pressure will be centered directly over the region tonight, leading to clear skies and light winds. Pwats will be on par with todays 12z readings, and will not have the cloud cover to hold up temps at all. As a result, think temps will be a degree or two colder over northern WI, so will issue a frost advisory for Vilas, Forest, and Florence counties. The surface high will shift slightly to the east on Friday and allow for deeper moisture to shift north across Minnesota and western Wisconsin. The eastern edge of this deeper moisture will likely reach into central WI during the afternoon, which should lead to a higher coverage of cu. Any precip chances should remain to the west of the region, however. Highs will be a couple degrees warmer than todays readings. .LONG TERM...Friday Night Through Thursday Issued at 240 PM CDT Thu Aug 24 2017 Focus in the long term will be on precipitation timing Friday evening through the weekend, along with lingering chances early next week. Showers should be confined to western Wisconsin late Friday afternoon. There are some model timing difference on when/if precipitation will reach the western forecast area (Vilas County south through Waushara County) Friday evening, but overall trends show low level moisture and WAA and the RRQ of a weak upper jet passing by Friday evening through Friday night. Therefore, kept a chance of showers in the far west. High pressure influence will still keep the eastern forecast area dry during this time. Rain chances slowly spread east Saturday afternoon and evening as the main low pressure system moves closer. Rain becomes more likely Saturday night into Sunday as the mid-level shortwave approaches northern Wisconsin. Medium range models are in general agreement that this energy stalls out over Wisconsin Sunday into Monday, and then dives south later Monday. This will result in periodic shower chances through Monday. PWats are around 1.50 inches at times Sunday, which is about half an inch above climatology normals. Did raise QPF values slightly on Saturday night/Sunday morning as some heavier rain is possible at times. Thunderstorm potential looks minimal as instability is not overly impressive. MUCAPES are mainly around 200 to 500 J/kg Sunday afternoon, so a few isolated thunderstorms are not out of the question. On Monday, any thunder would likely be confined to east- central Wisconsin as a small amount of instability lingers around there. Beyond Monday, the rest of the week looks quieter. Some afternoon showers are possible Tuesday, and a quick moving shortwave will bring a chance of showers Wednesday afternoon and evening, but the majority of the time will be dry. High temperatures will be cooler than normal through Monday, and then near normal for the rest of the period. Lows will be slightly below normal on Saturday morning, then fairly mild for late August. && .AVIATION...for 06Z TAF Issuance Issued at 1034 PM CDT Thu Aug 24 2017 Canadian high pressure will bring VFR flight conditions to most of the region through the TAF period, with the possible exception of patchy ground fog late tonight over north central WI. Mostly clear skies and light winds are expected through the period. && .GRB WATCHES/WARNINGS/ADVISORIES... Frost Advisory until 7 AM CDT Friday for WIZ005-011-012. && $$ SHORT TERM.....MPC LONG TERM......KLB AVIATION.......Kurimski
Area Forecast Discussion
National Weather Service Wilmington NC
1004 PM EDT Thu Aug 24 2017 .SYNOPSIS... A stalled front will bring scattered showers and storms tonight, but canadian high pressure will bring cool temperatures and dry weather this weekend on increasing northeast winds. We will be watching the tropics for possible development of low pressure off the Southeast coast early next week which could bring rainfall back into the forecast as early as Monday and Tuesday. && .NEAR TERM /THROUGH FRIDAY/... As of 1000 PM Thursday...Mainly due to convection across the Pee Dee Region, the front has been pushed well south of Marion and Florence, SC and is moving into Williamsburg county now. East to northeast winds now reported at FLO and MAO are proof of this. Along the coast we haven`t had any impetus (yet) to get the front moving and it remains stalled across southern New Hanover and Brunswick counties in North Carolina. A broad swath of northeasterly winds across the Outer Banks and the Crystal Coast should begin to push the boundary southward within the next couple of hours, with no significant changes to the previous wind forecast needed. Showers and t-storms are concentrated in an impressive cluster near the Florence-Williamsburg border now. These should move southward to the Santee River over the next few hours. Plenty of elevated instability within a humid airmass behind the front is creating scattered slow-moving showers all across SE North Carolina and Horry County, SC. It`s possible these clusters could grow into locally heavy rainmakers over the next few hours as they meander within slow, generally convergent low-level winds surrounding the front. Although my areal QPF across this region is a one-quarter to one-third of an inch, undoubtedly there will be a few spots that pick up 2 inches or more in the next few hours. Discussion from 730 PM follows... The surface front extends from roughly Southport, NC across northern Horry County, SC to near Marion and Florence, then southwestward into a weak surface low near Augusta, GA along the Savannah River. A rather impressive area of convection that developed earlier this afternoon near and north of Fayetteville, NC is probably associated with convergence along the frontal surface at 850 mb which is sliding southward. Mid-level winds are stronger than one might expect in August which has increased 0-6 km bulk shear values to around 30 knots. With modest CAPE values of 1000-2000 J/kg latest mesoanalysis is showing some bullseyes of Bulk Richardson numbers of 40-60 which may explain some of the brief supercellular signs one cell displayed earlier in Dillon County, SC. The HRRR has been performing quite well the past few days, (certainly better than the 18Z NAM today) and appears to have initialized well on its past few runs. The latest run shows the current convective cluster sagging southward into the Myrtle Beach area between 930-1100 PM. Forecast PoPs were raised to 60-100 percent near and along the path of this cluster through late evening. The surface front should pick up some southward momentum overnight and move offshore and south of the Santee River. This won`t clear us out as the shallow slope of the frontal surface will maintain mass convergence and unstable conditions aloft, particularly across coastal South Carolina and near Cape Fear. Scattered showers could continue across these areas through late tonight. No significant changes were made to forecast lows: 70 to lower 70s for most areas, except some upper 60s across interior SE North Carolina. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/... As of 300 PM Thursday...Temperatures will run a bit below climo through the period as high pressure wedges in from the northeast behind an offshore stalled frontal boundary. Sky cover is probably the trickiest part of the forecast. These wedges can be quite cloudy even though mid levels should dry adequately. There will be an inland/coastal gradient in moisture, highest along the coast due to the offshore boundary. Similarly it`ll be tough to rule out a sprinkle in those areas but measurable rainfall seems very unlikely. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... As of 300 PM Thursday...A stationary front will be located well offshore and S of the area Sun with an area of low pressure positioned on the front, but well offshore. High pressure will be ridging across the Carolinas from New England. A broad area of disturbed weather to our S continues to be monitored and a tropical system may begin to take shape early next week. The longer range models that do try to develop the system, do not indicate much in the way of vertical depth. Much too early to say what impacts, if any, will be felt on land across the eastern Carolinas. Will show dry weather continuing into Sun and then show increasing POPs Mon and Tue, highest along and near the coast. The rainfall forecast does hinge to a large degree on low pressure development, or not, off the Southeast coast and the interaction of this low with the front. Otherwise, high pressure to our N will take on a wedge configuration for a time, keeping temps near or below normal. Highs will be in the mid 80s with some locations only in the lower 80s early in the week, especially along the coast. Lows will be in the mid 60s to near 70 for much of the week, trending higher at the end of the period. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... As of 00Z...The surface front lies in between ILM and CRE along the coast of the Carolinas and extends westward to very near FLO. A line of showers and thunderstorms extending from LBT to FLO should move southward over the next couple of hours, affecting the CRE and MYR airports as soon as 02Z. MVFR conditions may drop briefly to IFR, especially at LBT where the heaviest storms are currently located at 00Z. Although the surface front should move southward late tonight, the shallow slope of the frontal surface aloft should maintain an environment suitable for the redevelopment of scattered convective showers across coastal South Carolina and perhaps coastal North Carolina through most of the night. Drier air building southward after daybreak Friday should lessen the potential we`ll see convective showers or storms develop. VFR conditions should prevail. Extended Outlook...MVFR ceilings could linger, especially near the coast Friday evening. VFR through the weekend. Showers may increase beginning Monday as a coastal low passes well offshore. && .MARINE... NEAR TERM /THROUGH FRIDAY/... As of 1000 PM Thursday...The front has moved very little over the next few hours, however the appearance of a broad swath of northeasterly winds over the Outer Banks and the Crystal Coast region means the front should begin to move southward within the next couple of hours. Radar reveals scattered showers developing near and just north of this front, and I see no reason why more showers and perhaps thunderstorms won`t develop through the night as the front dips southward. High moisture content of the atmosphere means these showers and storms will drop heavy rainfall with significant visibility restrictions expected for mariners. Discussion from 730 PM follows... The surface front has actually returned northward over the past several hours, roughly extending across Kure Beach, NC just north of Cape Fear. Virtually all model guidance indicates this northward drift should end shortly with the front returning southward overnight, passing through the coastal waters and south of the Santee River by daybreak Friday. This should turn the southerly winds in place across most of our forecast area northerly to northeasterly, but wind speeds should remain generally 10 knots. A line of showers with some gusty winds across the Interstate 95 corridor is sagging southeastward and should make it into the Myrtle Beach area around 1000 PM this evening. Model show this convective activity will likely be joined by new showers and embedded thunderstorms throughout the night, especially south of Cape Fear. SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/... As of 300 PM Thursday...Some pretty unsettled weather on tap for not only the short term but well beyond as well. Northeasterly gradient winds in place as high pressure noses in behind the offshore stalled frontal boundary. The strength of the gradient will be affected by the highly uncertain fate of low pressure that will develop over Florida and start moving northeast. This low may be tropical, baroclinic, or a hybrid, its thermal structure but one thing lending to the uncertainty. Currently its development seemingly hindered by the outflow from the rapidly intensifying Harvey. Regardless the system will lead to Advisory-worthy wind and seas from Saturday on. LONG TERM /SUNDAY THROUGH TUESDAY/... As of 300 PM Thursday...Persistent and brisk NE winds will likely require a Small Craft Advisory for a good portion if not all of the period. The rather tight pressure gradient will be the result of strong high pressure ridging down into the Carolinas from the N and an offshore front and area of low pressure. Will be watching the tropics early next week for the possible development of tropical low pressure off the Southeast U.S. coastal waters. NE winds will be around 25 kt Sun into Mon and may linger longer or even strengthen depending on any future tropical development. Seas will be 5 to 7 ft and perhaps up to 8 ft. Seas too may build higher depending on any future tropical development. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...RJD NEAR TERM...TRA SHORT TERM...MBB LONG TERM...RJD AVIATION...TRA
Area Forecast Discussion
National Weather Service Wilmington OH
936 PM EDT Thu Aug 24 2017 .SYNOPSIS... High pressure and a seasonably cool airmass will be in place across the region through Friday, before it works off to the east over the weekend. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... The only real forecast concern for tonight is with the broken area of 7kft-9kft clouds moving through the northern half of the ILN CWA. Roughly corresponding to around 750mb-700mb, most of the models have tried to dissipate this moisture a little too quickly, though recent HRRR runs have allowed a little more persistence. Overall, still thinking that this will eventually break up and/or dissipate to some extent over the next several hours, but mostly cloudy conditions are expected for a while longer. After looking at several recent model runs for T/Td and comparing to current conditions, the best course of action appeared to be leaving the current forecast essentially unchanged. Surface dewpoints are a little higher in the south, so some river valley fog can be expected on the Ohio / lower Scioto etc. Still expecting lower to middle 50s for min temps, with an outside shot at some upper 40s in the northern CWA if the clouds break up. Previous discussion > H5 s/w will affect the region for the first part of tonight, before it swings east into the Appalachians aft 03Z. This will provide pva and upper lift, which might cause the clouds to linger a little longer than a normal diurnal pattern would suggest. Therefore held onto a little more cloud cover from 00Z- 03Z than previous forecasts. After 00Z, went with mostly clear skies. With the airmass modification and the lingering cloud cover, went with lows in the lower to mid 50s tonight. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... On Friday, the region remains under nw H5 flow, but there doesn`t appear to be any definitive s/w, so while some diurnal cu is expected tomorrow, it shouldn`t be as much as today. The clouds should dissipate tomorrow evening leaving mostly clear skies again. Highs on Friday, should be in the upper 70s to lower 80s. Lows Friday night will be a few degrees warmer, in the upper 50s to lower 60s. && .LONG TERM /SATURDAY THROUGH THURSDAY/... The center of high pressure over the Great Lakes will move off to the east over the weekend, but it will continue to extend/influence our weather with dry conditions. Highs in the 70s on Saturday will warm slightly by Sunday into the upper 70s to the lower 80s. The upper level flow will become amplified across the CONUS as we head into next week. A mean mid level ridge will develop over the western U.S. as an upper level trough digs into the Great Lakes and Ohio Valley, moving very slowly east through mid to late week. This setup will increase the chances for precipitation Monday into Tuesday with the threat lingering into at least Thursday. The threat for thunderstorms will be tied more to the diurnal cycle, especially by Wednesday/Thursday. Temperatures will be slightly below normal for highs and close to normal for lows. Given the amplified pattern, much remains to be seen as to whether the remains of Harvey move northeast into the Ohio Valley region by next weekend. We will continue to monitor. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... Though diurnal cumulus will generally dissipate this evening, some larger stratocumulus patches will likely hold together over the DAY/CMH/LCK TAF sites going into the next 4-8 hours. Winds will become light, but should remain generally out of the north. River valley fog is expected overnight, including IFR conditions at LUK. No significant weather is expected on Friday, with diurnal cumulus and NNE flow at 10 knots or less. OUTLOOK...Thunderstorms are possible Monday into Tuesday. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...JGL/Sites NEAR TERM...Hatzos/Sites SHORT TERM...Sites LONG TERM...Hickman AVIATION...Hatzos
National Weather Service Jackson KY
1044 PM EDT Thu Aug 24 2017 .UPDATE... Issued at 1044 PM EDT THU AUG 24 2017 GOES 16 products showcasing high clouds moving east toward the Lake Cumberland region this hour. Otherwise clear skies are the story tonight, as we remain under the control of surface high pressure to the north. Overall temperatures in the valleys have been cooling quickly with temperatures in the upper 50s and here at JKL we remain at 64 degrees at 0240Z. Models are struggling with temperature trends as usual but the hires ARW had the best trend albeit too low. Only minor changes needed for high clouds and temperature trends. UPDATE Issued at 726 PM EDT THU AUG 24 2017 Minor update to deal with latest obs and trends. Otherwise forecast is on track. && .SHORT TERM...(This evening through Friday night) Issued at 355 PM EDT THU AUG 24 2017 19z sfc analysis shows high pressure over the region. For eastern Kentucky, this has kept temperatures on the cool side of normal today with comfortable humidity levels. Currently, temperatures are running in the mid 70s most places with dewpoints in the mid 50s. Winds have been generally from the northeast at 5 to 10 kts with occasional higher gusts. The models are in good agreement aloft with the longwave pattern affecting the region through the short term. They all agree that the core of the eastern trough through the Great Lakes will shift east and away from the area tonight with heights rebounding and the mid level northwest flow relaxing. This trend continues into Saturday morning as the area will be in between a developing trough to the northwest and the upper levels of `Harvey` well off to the southwest. Given the agreement will favor a general model blend with a lean toward the HRRR and NAM12 for details. Sensible weather will feature capital weather days with plenty of sunshine and cool conditions for mid to late summer. The lower RH will be noted as well in the afternoon. Each night we can expect mostly clear skies and a good radiational cooling environment allowing for moderate ridge to valley temperature splits. Also, look for valley fog to develop and become dense near the rivers toward dawn each morning. Have used the CONSShort as the starting point for most grids with the most significant adjustments made to temps at night to account for the terrain distinctions. As for PoPs, basically zeroed them out in the short term - in line with all guidance. .LONG TERM...(Saturday through Thursday) Issued at 308 PM EDT THU AUG 24 2017 The high pressure ridge will stay across the region through Sunday, keeping eastern Kentucky dry. The weather will turn more unsettled heading into next week although quite a bit of uncertainty remains on what happens with the remnants of Hurricane Harvey. At this point it does looks like a mid level trough will push east across the great lakes Monday and Tuesday, bringing an increased threat of showers and storms to eastern Kentucky. As we head into mid week, models really diverge on scenarios. If the tropical moisture spreads north, then we may keep rain around through much of the week. However, the 12z GFS has the system remain over the Gulf coast states until it weakens and dissipates and never brings that moisture northward. Right now, just too much uncertainty involved to get lost in the details, and will just keep the pops broad brushed through much of the week until confidence can improve. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) ISSUED AT 717 PM EDT THU AUG 24 2017 An area of surface high pressure to our north will remain the controlling factor in the weather through the TAF period. Most of the afternoon CU has dissipated and we are seeing mostly clear skies. These clears skies and high pressure will set the stage for valley fog overnight. The overall affect on TAF sites will be less given the drier air that is advecting into the region, However, did put a MVFR VIS in for SJS/SYM where fog could move into these sites toward dawn from the valley. There will also be some high clouds moving east into the region based on GOES 16 SAT data, but these will remain in the VFR range. Then model soundings suggest a few diurnal CU are possible by Friday afternoon, but the coverage is expected to be lass than today and remain at around 5 kft. The winds will be light out of the NE for the period. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...DJ SHORT TERM...GREIF LONG TERM...KAS AVIATION...DJ
Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
627 PM CDT Thu Aug 24 2017 .SYNOPSIS... Issued at 321 PM CDT Thu Aug 24 2017 H5 analysis this morning had high pressure over the Bahamas, as well as Baja California. In between these highs, hurricane Harvey was beginning to show up on the latest H5 chart and was centered about 300 miles southeast of Corpus Christi Texas. Further north, a trough of low pressure extended from Quebec south into the Mid Atlantic. Upstream of this trough, a shortwave trough of low pressure was present over western Wisconsin with a secondary wave noted over nern Missouri. Ridging was west of the trough, and extended from Montana north into Nunavut Canada. Across the intermountain west, very weak mid level flow was present with numerous weak shortwaves noted. As of 12z this morning, shortwaves were noted over northern Utah, eastern Utah, western New Mexico and Idaho. Across western and north central Nebraska, a weak disturbance was lifting across the area and has led to abundant mid level cloudiness this afternoon. Some light rain showers and evening an embedded thunderstorm or two has occurred this morning and into the early afternoon hours. && .SHORT TERM...(This evening through Friday) Issued at 321 PM CDT Thu Aug 24 2017 Precipitation chances over the next 24 hours are the main forecasting concern. Low level moisture has definitely increased across the area over the last 24 hours as dew points were in the upper 50s and 60s across western and north central Nebraska. Fcst cape this afternoon is expected to reach 2000 to 3000 J/KG from southwest into central and northeastern Nebraska. At the surface, a weak convergent zone was present from near O`Neill, to Broken Bow to north of North Platte, to the sern Nebraska Panhandle. As the upper level wave, currently over western Colorado, crosses the Rockies this afternoon, am expecting thunderstorms to fire across the high plains of Colorado and Sern Wyoming late this afternoon. As this feature lifts into eastern Colorado, there will be an increased threat for showers and thunderstorms this evening. At this time, am expecting the best chances for thunderstorms INVOF the low level convergence zone from swrn into northeastern portions of the forecast area. In these areas, the inherited forecast had the highest pops left the forecast as is, decreasing pops in the north central and northwestern zones. Deep layer shear this evening is fairly meager on the order of 20 to 25 KTS so there will only be a meager threat for severe storms. However, with PWATS in the 1.0 to 1.5 inch range along the boundary, heavy rain could be an issue this evening. Overnight, convection will push east, exiting the area after midnight. Overnight tonight into Friday morning, the short range model solutions lift the surface boundary north into South Dakota. Am expecting fairly early thunderstorm initiation Friday afternoon as there is little or no cap present by 21z. Will favor the highest pops in the north INVOF the surface boundary. .LONG TERM...(Friday night through Thursday) Issued at 321 PM CDT Thu Aug 24 2017 Mid range...Friday night into Sunday: The threat for thunderstorms will continue Friday night into Sunday as a couple of weak upper level disturbances traverse, South Dakota and Nebraska. Thunderstorms are expected to be ongoing across South Dakota and northern Nebraska Friday evening. This activity will shift into eastern Nebraska overnight. On Saturday a second upper level disturbance will track from the Panhandle into central Nebraska with increased chances for thunderstorms Saturday afternoon and evening. This will be followed by one final weak disturbance on Sunday. Sunday night through Thursday: A pattern shift will begin to take shape late Sunday into next week. A broad ridge of high pressure will build across the western CONUS. This will place the forecast area in due north mid level flow, which will greatly limit any pcpn chances. Highs will generally be seasonal as the warmest air will reside off to the west of the forecast area. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 627 PM CDT Thu Aug 24 2017 The forecast follows the HRRR model but with low confidence as all of the rapid refresh models have been struggling predicting storm development and evolution. The good news is none of the models except the RAP show VFR conditions but it is possible MVFR cigs will develop in the wake of tonight`s thunderstorm activity. At some point this evening, the thunderstorms should begin to grow upscale toward I-80 and S/Ncntl Neb and become numerous. The storm activity should last most of the night and exit the region around 12z Friday. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Buttler SHORT TERM...Buttler LONG TERM...Buttler AVIATION...CDC
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
922 PM EDT Thu Aug 24 2017 .SYNOPSIS... A stalled front near the North Carolina/South Carolina border will move little overnight. Strong high pressure will build in from the north Friday through Sunday. An area of low pressure is forecast to develop along the stalled frontal boundary off the Florida coast Sunday and slowly lift northeast along the Southeast coast early next week. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... As of 920 PM Thursday...Cooler E/NE flow prevails across eastern NC in wake of the cold front which crossed the area this morning. With the loss of diurnal heating, widely scattered shower activity over our area has dissipated this evening. The HRRR and NSSL WRF do indicate convection developing mainly offshore of the SE coast overnight as a weak low moves along the stalled front offshore. If this activity does develop it should remain mainly offshore so will indicate more of drying trend inland and north with only slight chance PoPs SE coast. The drier airmass in place across the region will lead to cooler low temps with readings in the mid/upper 60s northern and central CWA with lower 70s closer to the coast. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/... As of 255 PM Thursday...High pressure will ridge south from the Great Lakes Friday with an NE/ENE flow regime across eastern NC. Temperatures and especially dewpoints will be a little below normal for Friday with highs in the low/mid 80s and dewpoints over all of the CWA in the mid/upper 60s. Model time-sections should drying in the boundary layer and very dry air above 700 mb, but deep moisture linger in the 850-700 mb layer, so would expect to see scattered to broken clouds at times on Friday && .LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/... As of 250 PM Thur...Below normal temps expected this weekend and through most of next week. Unsettled conditions are expected along the coast this weekend, while it will be mostly dry inland. More widespread rainy conditions are likely next week as we continue to watch for the possible development of a tropical low along the SE coast, though much uncertainty remains regarding this system. Friday Night through Sunday...Strong high pressure will build behind a cold front that is expected to stall in the vicinity of the Gulf Stream. Still, widely scattered showers will possible along the coast, while further inland it should be mostly dry. Low level thickness values, and NE flow, support below normal temps with highs in the upper 70s to mid 80s and overnight lows in the low/mid 60s inland and mid 60s/70 degrees along the coast. Monday through Thursday...Models continue to show possible tropical low development along the stalled frontal boundary off the SE coast this weekend into the middle of next week. Much uncertainty remains on how this system will evolve, given how far out in time, and varying model solutions/lack of run to run consistency. Low is forecast to strengthen off the FL coast Sat night and Sun, slowly lifting NE Mon through Wed. Looking at the 12z guidance suite, the CMC is still the strongest and brings the system closest to the NC coast, while the ECMWF and GFS offer a weaker solution, and are slightly further off the coast. More widespread precip is possible Monday onward, but will keep chance PoPs with so much uncertainty still to be resolved. High temps through the period, generally in the upper 70s to low 80s, with overnight lows 60-70 degrees. && .AVIATION /01Z FRIDAY THROUGH TUESDAY/... Short Term /through Friday/... As of 655 PM Thursday...Main question is whether ceilings will lover from current VFR with high Cirrus clouds and scattered high based Cumulus currently across the area. Although the low level flow is out a favorable easterly direction, I`m not really seeing a strong signal in any of the guidance for either fog or low ceilings overnight. Thus will issue a VFR forecast and indicate scattered MVFR clouds late. Friday diurnal heating is expected to promote widespread Stratocumulus clouds with VFR bases. Long Term /Friday Night through Tuesday/... As of 320 PM Thur...Predominant VFR conditions expected through most of the period. Rain showers and isolated thunderstorms will be possible Monday and Tuesday with the best chances closer to the coast. This could lead to some brief sub-VFR conditions. && .MARINE... Short Term /Tonight and Friday/... As of 920 PM Thursday...High pressure building into the waters will continue to produce NE/E flow 10 to 15 kts with occasional gusts to 20 kt through Friday. Seas are expected to remain 3-4 feet through Friday. Long Term /Friday Night through Tuesday/... As of 325 PM Thur...Strong winds and dangerous seas expected to develop this weekend and continue into next week, with the potential for tropical low development along the southeast coast. Strong high pressure will build in from the north Friday through Sunday. Models continue to show the potential for tropical low development along the stalled frontal boundary off the SE coast this weekend into early next week. There is still quite a bit of uncertainty given how far out in time and the varying model solutions and lack of run to run consistency. Winds initially ENE 15- 20 kts will increase Saturday night, becoming NE 20-25 kts. Winds continue to be NE/ENE 20-25 kts through Tuesday, with 25-30 kts possible across the central waters Monday night. Seas will initially be 3-5 ft Saturday, but will quickly build to 4-6 ft across the central and southern waters Saturday night. All coastal waters will build to 5-8 ft Sunday afternoon, and then 6-10 ft Monday, with the highest seas over the outer central waters. Seas will begin to calm some on Tuesday dropping to 6-9 ft. Given the uncertainty on how this system will evolve, mariners should continue to monitor the forecast over the next several days. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...Beach Hazards Statement from 8 AM EDT Friday through Friday evening for NCZ095-098-103-104. MARINE...None. && $$ SYNOPSIS...JME/CTC NEAR TERM...JME/CTC SHORT TERM...CTC LONG TERM...SGK AVIATION...JME/CTC/SGK MARINE...JME/CTC/SGK
Area Forecast Discussion
National Weather Service New York NY
1050 PM EDT Thu Aug 24 2017 .SYNOPSIS... Canadian high pressure will gradually build through Saturday, and dominate into Monday and perhaps Monday night. Offshore low pressure to the south may impact the area Tuesday into Wednesday, especially along the coast, while the high remains to the north and west. A weak cold front will approach on Thursday. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... Radiational cooling proving to be efficient this evening just like the previous evening for some locations. Clouds have been minimal across much of the region and with light winds once again, has led to the efficient radiational cooling. Temperatures have not lowered as much where there has been more clouds. The radiational cooling will be mitigated though overnight when clouds increase from the west with the passage of the shortwave. Overall, just some slight adjustments with temperatures and dewpoints with otherwise no other remarkable changes made. Surface high pressure builds across the Great Lakes region tonight. Aloft, shortwave and associated PVA passes overhead overnight. Enough dry air along with low/mid level moisture expected to be rather shallow should preclude any rain from reaching the ground for our area, although a few late night sprinkles are possible. An isolated shower cannot be ruled out. The HRRR model indicates some light shower activity towards daybreak Friday just missing the forecast region to the SW. Cool air remains in place, but broken clouds should prevent ideal radiational cooling, thus resulting in lows from the low 50s in rural and interior locations to the mid 60s near NYC Metro. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY/... Initial shortwave passes Friday morning, with overall trough remaining across the northeast. Surface high pressure builds east across New England through this time frame providing dry conditions. However, with center of high pressure still well north and west of the region and with a cold pool lingering aloft, the daytime surface warming will initiate development of diurnal cumulus clouds. Bufkit indicates these clouds between 6-9kft to become scattered to broken coverage in the afternoon and could linger along the coastal sections into Friday evening. However, think with the loss of daytime heating Friday night, the trend will be for generally clearing skies with the loss of diurnal instability. Clear skies still expected on Saturday too with the center of high pressure moving within closer proximity of the region. Temps look to remain at or below average. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... A large high pressure system covering much of eastern North America should continue to dominate through at least Monday, possibly into Monday night. Temperatures during this time will run a few degrees below average, more so at night given radiational cooling under mostly clear skies and fairly light winds. Uncertainty then increases quite a bit as a very complex scenario develops, with a weak omega block developing from the northern Plains eastward to the Canadian maritimes, and presence of a developing low of uncertain characteristics along the Southeast coast. GFS/ECMWF show this low remaining well out at sea and looking more baroclinic or subtropical in nature, with no more than a moderate ENE flow developing mainly along the coast, while the last couple of runs of the GEMnh offer more concern for a potential tropical impact or close call. That latter solution, while an outlier as have been most longer range GEMnh forecasts of tropical development this season, would be plausible if the low remained completely tropical in nature and separate from a frontal boundary to its north, and if the upper high over the western Atlantic phased with that of the omega block over the Northeast and inhibited out-to-sea progress. That said, even if the low were to be more baroclinic in nature, past experience has often shown that offshore lows forecast by the global models often take tracks closer to the coast in the presence of blocking and/or an upper trough to the west. With all that in mind, have forecast increasing ENE winds mainly along the coast and low chance PoP for Tue night into Wed, and anticipate at least a high risk of rip currents during this time if not high surf. For any potential tropical development of this system, please refer to NHC outlooks. This low should pass off to the east by Thursday, with a return to near average temperatures as a weak cold front approaches from the NW. && .AVIATION /03Z FRIDAY THROUGH TUESDAY/... A vigorous shortwave passes through late tonight with little impact except some increasing cloud cover. High pressure then builds in across the region Friday into Friday night. VFR thru the TAF period. SHRA/TSRA over central PA this evening are expected to dissipate as they approach the NYC/NJ metro terminals late tonight/early Fri morning. SCT-BKN cu development likely at 5 to 7 kft Fri afternoon. Light N/NW winds Friday morning, likely back to the W for south coastal terminals during the afternoon. Low prob for S/SSW sea breeze development at KJFK/KISP Fri aft, with moderate potential for SW sea breeze at KBDR/KGON. NY Metro Enhanced Aviation Weather Support... Detailed information...including hourly TAF wind component fcsts can be found at: http:/ KJFK TAF Comments: Low prob of southerly sea breeze Fri afternoon. Occasional W/WNW gusts 15 to 20 kt possible in the afternoon. KLGA TAF Comments: Occasional NW gusts 15 to 20 kt likely in the afternoon. KEWR TAF Comments: Occasional WNW gusts 15 to 20 kt likely in the afternoon. KTEB TAF Comments: No unscheduled amendments are expected. KHPN TAF Comments: No unscheduled amendments are expected. KISP TAF Comments: Low prob of SSW sea breeze Fri afternoon. .OUTLOOK FOR 06Z SATURDAY THROUGH TUESDAY... .Saturday Night-Tuesday...VFR. E/NE winds. && .MARINE... High pressure builds across the waters through Saturday. Winds remain rather light through the period, with a predominate N to NW flow expected tonight and Friday, then NE/E Saturday. The development of afternoon troughs may result in winds shifting for a time both Friday and Saturday. Ocean seas expected to remain 3 ft or less, with 1 ft or less across non ocean waters through Saturday. With high pressure to the north and low pressure to the south, ENE flow should increase early next week. SCA conditions, first in the form of hazardous seas, are possible on the ocean waters as early as Sunday night, and appear more likely Mon into Tue. Wind gusts up to 25 kt are also likely on the ocean on Tue. && .HYDROLOGY... No hydrologic impacts are expected through early next week. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...Goodman/PW NEAR TERM...JM/PW SHORT TERM...JM/PW LONG TERM...Goodman AVIATION...NV MARINE...Goodman/PW HYDROLOGY...Goodman/PW
Area Forecast Discussion
National Weather Service Mount Holly NJ
930 PM EDT Thu Aug 24 2017 .SYNOPSIS... Canadian high pressure will build southward into the region through this weekend before progressing offshore around the middle of next week. This high will bring a period of dry and seasonably cool weather to the Mid-Atlantic through at least the beginning of next week. A tropical or subtropical low is expected to develop east of the Florida coast this weekend and lift slowly northeastward off the East Coast next week. At this time, the system is expected to remain well southeast of the area. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... Dirunal cu has dissipated with loss of daytime heating. As a result, strong radaitional cooling conditions have developed due to the combination of clear skies and light to calm winds. Temps across much of the forecast area have dropped into the mid 60s, but some parts of NJ are down into the low 60s, and the Poconos have dropped into the 50s. Can expect temps to drop off several more degrees through this evening. H5 trough with strong shortwaves moving through western NY and PA and will pass through the region after midnight tonight. This will bring a BKN-OVC mid-deck with the approach and passage of that trough. HRRR continues to bring precip through the region during the overnight hours, but this seems overdone compared to the 18Z NAM/18Z GFS/12Z ECMWF. 18Z CMC-GDPS has some light precip as well, but the overall trend is to keep things generally dry. Will carry isolated showers/sprinkles across the Lehigh and Delaware Valleys, mainly from after midnight through the pre- dawn hours of Friday. When the clouds return later tonight, temps should hold steady or slowly rise. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/... Partly to mostly sunny. Seasonable. Max temps 1 to 5 degrees below normal. 850 temps maybe 1C less than today so temps 1 to 2F cooler than what occurred on Thursday. Light northwest winds except seabreezes developing on the coast. A couple of models show isolated light shower potential but now, we are not forecasting any sprinkle activity since we`re unsure where it might occur, if at all. This forecast was a 50 50 blend of the 12z/24 GFS/NAM MOS. && .LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/... An extended period with fair weather will continue in the long term. High pressure will remain in control of the weather as it slides across southern Canada and then off into the Atlantic early next week. The models are in general agreement with the above situation. The GFS model is showing some light precip near the shore areas Saturday with the low level flow being onshore at that time. I don`t feel confident enough with this attm to raise pops into the slgt chc range. Cloud cover across the coastal areas was increased however. Temperatures will be a couple degrees below normal for late August, overall pleasant for this time of year. Next week, the onshore flow with the retreating high and an upper trough developing across the east U.S. will result in increasing chcs for clouds and showers. We therefore have continued with the slight chc or low chc pops for most areas at those times. A sub- tropical low over the east coast towards the middle of next week, should remain far enough away to keep any significant showers activity out of our CWA. This will be something to watch however. Temperatures are expected to stay near seasonal norms, with more humidity however. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Tonight...VFR. BKN-OVC deck at 9000 feet will spread into the region after midnight tonight. A few sprinkles or light rain showers are possible, mainly at KABE/KRDG and possibly KILG. LGT/VRB winds. Friday...VFR. Sct-bkn aoa 6000 ft. Light northwest winds with max gusts 15 kt. An afternoon wind shift to southeast is possible at ACY. Outlook... Fri night thru Tuesday...A prolonged period of VFR conditions expected with high pressure across the area. A few low clouds near the shore possible Saturday. Winds mostly under 10 knots. && .MARINE... Winds and seas are expected to remain below small craft advisory conditions through Friday. Outlook... Friday night through Sunday...Winds and seas below advisory criteria. Fair weather. Sunday night through Tuesday...SCA seas developing on the ocean Sunday night and Monday then persisting into Tuesday. Sub-SCA seas over Delaware Bay. Mostly fair weather expected. Rip Currents... There is a Low risk for the development of dangerous rip currents at NJ and DE ocean beaches on Friday. However, with late day sea breezes developing, the shift to a S to SE wind may result in a localized moderate risk for the development of dangerous rip currents, mainly at NJ ocean beaches late in the day. Confidence is low at this time, so will keep the forecast risk at Low. Low does not mean NO risk! Please be smart selecting where you swim. Safety requires a flotation device available nearby and preferably swimming within sight of a lifeguard. Also...not only are we hearing stories of bacteria here and there along the NJ coast, but we were informed of a few Man O War stings. So even in this outstanding weather pattern, follow the advice of local officials regarding your swim zones. IF anyone is seeking advice for choosing swim days along the NJ and DE coasts...the next couple of days should be potentially nicer versus next week (bacteria and Man o Wars issues excluded) Next week, the swimming safety and comfort is expected to diminish as noted below. Early next week...the risk for the formation of dangerous rip currents should increase to at least moderate. Atlantic waters will become rough and more difficult to manage for swimmers because of increasing easterly swells and persistent onshore flow in association with the high re-centering to our north and some sort of low pressure system moving northeast, off of the southeast coast of the United States. The result, the building of an 8 second easterly swell...possibly to 7 feet or so by Monday or Tuesday, at least along the southern NJ and DE coasts. && .CLIMATE... Barring unforeseen rain, the period thru next Monday could potentially be only our second rain-free stretch that spans at least five days in what has otherwise been a very wet summer. June 8-13, was the other 5+ day dry stretch this summer, was technically not rain free as MPO reported 0.01 inches of rain on both 10 June and 13 June. The last time all eight of our climate sites have not recorded any measurable rainfall for at least five consecutive days was March 2-6, 2017 (honorable mentions: 15-19 May except for 0.02 inches at MPO on 15 May and the previously mentioned 8-13 June period). && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...None. && $$ Synopsis...CMS Near Term...Drag/MPS Short Term...Drag Long Term...O`Hara Aviation...Drag/MPS/O`Hara Marine...Drag/MPS/O`Hara Climate...
Area Forecast Discussion
National Weather Service Pueblo CO
346 PM MDT Thu Aug 24 2017 .SHORT TERM...(This evening through Friday) Issued at 346 PM MDT Thu Aug 24 2017 Upper wave pushing across CO today, with area of sct tsra moving slowly eastward across the mountains at mid-afternoon. While persistent high level cloud deck has limited instability somewhat across the region, CAPE has still pushed into the 1000-1500 J/KG range along and east of the mountains, with some briefly vigorous updrafts noted on radar since 20z. Main limiting factor for storm strength and coverage today and tonight is very weak wind shear, with 0-6km values running 20kts or less across the region. Forecast for the remainder of the afternoon and evening follows the HRRR and NAM fairly closely, with sct storms pushing gradually eastward from the mountains across the plains, before storms diminish toward KS border by midnight. Suppose one or two storms could be briefly strong, with heavy rain and small hail possible. Models not quite as enthused about storms over the far eastern tier of counties as runs earlier this morning, so will nudge pops downward along the KS border somewhat for this evening. Skies clear overnight as wave pushes east, leaving seasonably cool temps in its wake by early Fri morning. Expect a downturn in convection across the area Fri as air mass dries slightly and weak subsidence develops across the region. Mountains will still see isolated storms, but will keep most lower elevations dry as convection stays close to the higher terrain. With less cloud cover, max temps should creep upward a few degf, especially along and east of the mountains. .LONG TERM...(Friday night through next Thursday) Issued at 346 PM MDT Thu Aug 24 2017 A relatively tranquil longer term forecast is in the offing(outside of a later Sunday into Monday time-frame) in combination with above average temperatures. Primary longer term meteorological concerns for the forecast district continue to be temperatures and pops. Latest longer range forecast model soundings, computer simulations and PV analysis still suggest that upper ridging centered near the 4-Corners Saturday shifts over Nevada and Utah from Sunday into Wednesday in advance of relocating to near the 4-Corners region again by next Thursday. Also, varying degrees of eastern Colorado lee-side troughing is still anticipated from Friday evening into Saturday night in advance of a north-northeasterly surface surge moving across the forecast district Sunday. Then, next round of eastern Colorado lee-side surface troughing is projected to develop from later Monday into next Thursday. The combination of the relatively moist north-northeasterly surface surge on Sunday in addition to passing upper disturbances from later Sunday into Monday will allowed enhanced precipitation chances over sections of the forecast district during this time-frame, otherwise generally low-grade pops in combination with above seasonal temperatures are anticipated during the balance of the longer term over the majority of the forecast district. Also, latest temperature trends still continue to suggest that minimum and maximum temperatures during the longer term should generally run at or above late August climatological averages over the forecast district with warmest conditions anticipated Saturday and Wednesday. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 346 PM MDT Thu Aug 24 2017 VFR conditions expected at COS, PUB and ALS terminals over the next 24 hours. Mountain convection will spread slowly eastward for the remainder of the afternoon and into the evening, and will carry a VCTS at all terminals from 21-22z through about 03Z this evening. Brief MVFR conditions and small hail will be possible with stronger storms along and east of I-25 into the evening. Storms gradually end toward midnight, with clearing skies overnight. Much less in the way of tsra over the region on Friday, and will likely keep convection out of all tafs for Fri afternoon, with just a few mountain storms expected. && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$
Area Forecast Discussion
National Weather Service Tucson AZ
858 PM MST Thu Aug 24 2017 .SYNOPSIS...A low grade monsoon pattern will prevail into the middle of next week. Adequate moisture will produce isolated to scattered mainly afternoon and evening thunderstorms, with the greatest coverage east of Tucson. Daytime temperatures will be near or slightly above seasonal normals. && .DISCUSSION...We`ve dried out a bit over the past 24 hours, with the 00Z KTWC sounding down to 1.2 inches, and satellite estimates continuing that trend (suggesting values near or below 1 inch for much of SE AZ). Surface dew points are down 5 to 10 degrees as well (generally in the 50s outside of border areas). Deeper moisture not far away in Sonora and Chihuahua, and we`ll see an ebb and flow of moisture fluctuations over the next several days. Likely low-grade monsoon thunderstorm coverage most days, favoring mountains. Please see the previous discussion below for details. && .AVIATION...Valid thru 26/06Z. Clearing overnight. Some isolated storms possible on Friday although they should favor the higher terrain areas. Otherwise, VFR conditions with surface wind variable in direction, mainly less than 12 kts. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Isolated to scattered mainly afternoon and evening thunderstorms will occur into next week. Thunderstorm coverage will fluctuate daily but locales east of Tucson will generally be favored. 20-foot winds will generally exhibit an easterly component starting Friday, but will mainly remain below 15 mph. && .PREV DISCUSSION...Latest runs of the HRRR as well as UA WRFs and other convective allowing models suggest it should be a quiet night across the lower elevations. Hard to argue against that theory based on the flat cu visible on area webcams. Much of the same is forecast on Friday as GFS/NAM/ECMWF all indicate slightly drier air in the deserts as compared to today. With weak anticyclonic flow forecast in the mid levels, even cu may struggle to develop tomorrow afternoon west of Tucson. Mountain showers and storms will once again be possible although nowhere near as widespread as what was seen Wednesday. Looking into the weekend and beyond reveals a large scale shift of the mid level high to our north, with northeasterly flow forecast across the area through the middle of next week. In theory this pattern should be conducive for shower and storm development but BL moisture isn`t nearly as high as it could be with mean mixing ratios only forecast to reach 5-6 g/kg. Consequently afternoon MLCAPES are only forecast to reach less than 500 J/kg. Granted this is still several days away but it looks to be a relatively low grade monsoon pattern all the way through the end of next week. As for temps, look for at or slightly above normal readings every day through the end of next week. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && $$ Meyer/Leins Visit us on Facebook...Twitter...YouTube...and at