Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/05/17

Area Forecast Discussion
National Weather Service State College PA
1004 PM EDT Sat Nov 4 2017 .SYNOPSIS... A warm front will lift northward through the region Sunday followed by a strong cold front on Monday. After a wet day on Monday, a ridge of high pressure will build across the region for the middle of next week with colder temperatures. A much stronger cold front will move in by next Friday, as a large high pressure system from the northern plains with abnormally cold air builds eastward on Friday. && .NEAR TERM /UNTIL 8 AM SUNDAY MORNING/... The area of rain has blossomed as expected as it moved into the sern cos. Still, many locations have picked up only one or two tenths of an inch of rainfall. A few spots around the Harrisburg metro are closer to a third of an inch. It is tapering off there as forcing/weak LLjet moves off to the east. Bright band on radar around 9kft makes it look worse/heavier than it really is. It is that time of year when the melting layer starts to rear it`s head. Have called the precip for much of the rest of the night drizzle as the vertical extent of moisture is not that deep - generally less than 5kft. Also, the veering low level wind profile should make a broad area of upglide into the central mtns. Temps should move little with lots of clouds and mainly southerly flow. Prev... Rain sliding through on time, but overall, it is very light and few restrictions are being seen at local airports. The rain will slow down a bit and redevelop over the SE half of the area as SWrly flow increases in the cloud layer. Prev Prev... The nose of the surface high that extends from southern New England down into the Mid Atlantic states is retreating off to the east, paving the way for increasing moisture snaking in from the southwest. The nearest rain is over the panhandle of WV making slow but steady progress northward. This will likely be the rain we experience over southern and central PA over the next 8-12 hours, before more rain associated with the warm advection associated with advancing warm front enters from the NW. The HRRR takes the bulk of rain through my southern zones through late evening before bringing new showers into the NW around or shortly after midnight. It all points to a fairly high POP but low QPF forecast overnight. Overnight lows in the 40s will actually be quite mild for early November, averaging a couple of degrees either side of 10 deg warmer than normal. && .SHORT TERM /8 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/... The best chance of rain Sunday will be over about the northern half of the region Sunday as the warm front tries to erode the cool air damming wedge in place over the Central Mountains. As the warm air aloft begins to mix down, we will likely see some breaks develop in the clouds across the Laurel Highlands. Elsewhere, cold air damming will hold in the low ceilings, but spotty light rain and drizzle is likely to abate by afternoon, when model soundings show layer of moisture becoming quite shallow. Model blended guidance supports high temps Sunday between 60-65F over most of the forecast area, about 5-10 deg above normal. && .LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... Models been showing a cold front moving in Monday, bringing another round of showers to the area Sunday Night and Monday. I did slow down the back edge of the showers on Monday. Left mention of thunder in. SPC day 2 has a large area of higher storm potential for Sunday just to the west of our area. Not seeing a deep low or height falls, but PW values come up some, and LLJ in place. Another factor is EML, given southwest flow of abnormally warm air across the southern plains. Thus support for thunder. I did up QPF to the northwest, to fit better with the models and other offices. Fast moving waves at 50 mb could bring a shower toward southern PA, later Tuesday. A strong cold front moves in by Friday, may be very little QPF. Main thing will be a brief window for lake effect, but the main response may be more off Ontario than Erie. Did not bring lows next Saturday Night up as much as the superblend, given how strong the high is. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... 0040Z Radar has light reflectivity`s moving into central PA with MVFR cigs at AOO. Light rain has started at the southern TAF sites. Have adjusted timing of the onset of the restrictions and as the strong flow aloft has stalled have either dropped LLWS from the southeast TAFs. As the warm front enters in overnight into tomorrow, the moisture will continue to stream through into the region. Expecting cigs and vsbys to progressively get worse. IFR is possible at the central and western TAF sites around 06Z and around LNS by 13Z. Drizzle and IFR cigs remain persistent through Sunday morning with just gradual improvement over the south and southwest by midday into the afternoon. Northern half will likely hang on to restrictions all day. Outlook... Mon...Widespread MVFR/IFR with a cold front. Thunderstorms are possible as well. Tue...Mainly VFR. Wed-Thu...No sig wx. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...La Corte/Martin NEAR TERM...Dangelo/La Corte SHORT TERM...La Corte LONG TERM...Martin AVIATION...Ceru
Area Forecast Discussion
National Weather Service Hastings NE
653 PM CDT Sat Nov 4 2017 .SHORT TERM...(This evening through Sunday) Issued at 241 PM CDT Sat Nov 4 2017 Plenty of mid level cloud cover continues to stream across the region this afternoon as most of the low level stratus from this morning has eroded. This has allowed for a few sun breaks in spots...along with allowing temperatures to climb into the lower 50s the past hour or so. As a result...did tweak afternoon temps upward a bit as originally this forecaster was a bit too pessimistic with low cloud cover for today. For tonight...there is a bit of uncertainty with the forecast as with lots of mid level cloud cover across the area this afternoon...have a difficult time seeing a rapid fall off in temperatures overnight ahead of an approaching cold front...which if realized...could potentially allow some fog to form. Despite this low potential...short term models such as the HRRR are indicating there could be the development of widespread dense fog across the local area during the late night through overnight hours ahead of the approaching front. Because of this...thought it was prudent to at least add patchy fog to the forecast generally south of highway 6...with a rapid erosion of any fog that does develop as the aforementioned cold front tracks south across the local area. In addition...while there is only a week signal in model think there is a potential for at least some sprinkles across our north with forcing from the also added this low end probability to the forecast. What is more certain is that a mostly cloudy and blustery day is anticipated across the local area Sunday. With lots of low level stratus around and strong cold air advection...should see afternoon temps struggle to climb out of the mid 40s...with most locations seeing readings 10 or more degrees below this afternoons highs. In addition...gusty northerly winds will filter in behind the front...making for a relatively unpleasant day across the region tomorrow. .LONG TERM...(Sunday night through Saturday) Issued at 241 PM CDT Sat Nov 4 2017 Generally below normal temperatures along with a few small chances for precipitation are expected through the extended periods. Tuesday appears to be the coldest day of the extended periods behind another cold front...when temperatures are not forecast to climb out of the 30s and a weak disturbance could bring some light snow showers to the local area. That said...the better moisture at this time appears to be focused to our west...and only light snowfall amounts...from a dusting to less than an inch...are anticipated across the local area from the late Monday night through late Tuesday night period. Cool air will then linger across the local area for several days...with a potential warming to near seasonal norms late in the period as a transitory ridge is forecast to slide across the plains late in the week...with another chance for some light precipitation possible next weekend. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Sunday) Issued at 649 PM CDT Sat Nov 4 2017 Main issue will be a cold front moving in tonight. Just before the cold front passes through, we could see some lowering visibility, but confidence is not high if this will happen, and if it does, how low, and how long would be another big question. It appears that lower visibility may be more likely to the south of the terminals. Introduction of MVFR ceilings are expected with the arrival of the cold front. Wind will be a bit gusty with the cold front passage as well overnight. && .GID WATCHES/WARNINGS/ADVISORIES... NE...None. KS...None. && $$ SHORT TERM...Rossi LONG TERM...Rossi AVIATION...Heinlein
Area Forecast Discussion
National Weather Service Green Bay WI
858 PM CDT Sat Nov 4 2017 Updated aviation portion for 06Z TAF issuance and new information added to update section .UPDATE... Issued at 845 PM CDT Sat Nov 4 2017 Drizzle will probably diminish overnight as low-level flow veers overnight. But light rain/showers closer to the cold front advancing into the area from the west will likely shift into north-central Wisconsin later tonight. But the main concern is fog formation. Visibilities have been slowly edging down but are still generally AOA 1 1/2 miles across the forecast area. Areas where snow is still on the ground are certainly at risk of having some dense fog, but lower visibilities over southeast Wisconsin could expand north into east-central Wisconsin as well. Plan to handle with an SPS for now, but am ready to post a dense fog advisory if there is a significant downturn in visibilities. && .SHORT TERM...Tonight and Sunday Issued at 233 PM CDT Sat Nov 4 2017 The latest RAP analysis and satellite/radar imagery show a cold front over the northern Plains and high pressure positioned over the east coast. Light showers continue over northeast Wisconsin early this afternoon associated with a weak shortwave moving across the region. These showers should exit later this afternoon. But broad low level warm advection may also lead to drizzle redeveloping. As the front moves towards Wisconsin late tonight, light precip trends and fog potential are the main forecast concerns. Tonight...Low level warm advection will continue across the region, ahead of a cold front that will move across western Wisconsin after midnight. Moisture will remain trapped beneath an inversion, with saturation extending upward into the 850-700mb layer during the evening. Though progged soundings indicate that the top of the saturated layer will lower some this evening, the depth should remain sufficient for widespread overcast conditions with periods of drizzle. Temps should not move very much, so not expecting any freezing drizzle. However, with some snow cover over north-central and far northeast WI and a moist boundary layer, could see dense fog develop late tonight. As the front moves closer to north-central WI late, decent forcing in the left front quad of a jet streak could bring more widespread shower activity. Nearly steady temps tonight in the mid 30s to low 40s. Sunday...The front will continue to move east across north-central and northeast WI. Showers will likely impact north-central WI for this first half of the morning before they lift northeast into the Upper Peninsula. The showers are expected to become more widely scattered as the front moves into eastern WI around midday. With the passage of the front and shifting of the winds to the northwest, should see any fog lift shortly thereafter. Highs ranging from the upper 30s to upper 40s. .LONG TERM...Sunday Night Through Saturday Issued at 233 PM CDT Sat Nov 4 2017 Sunday night and into much of the work week will consist of mainly dry conditions with temperatures below normal levels. Colder air may provide some periods of minor lake effect snows far north. Weak northwest flow or near zonal flow will keep primary weather systems well south and north of the area for at least the first half of the work week. A couple of cold fronts will keep temps chilly along with brief periods of snow shower activity across the far north as winds turn northwest behind the cold fronts. Progs are attempting to focus the first period of lake effect snow showers Sunday night after the Sunday cold front. Another cold front with weak short wave slides over Monday afternoon and evening followed with northwest winds late Monday night into Tuesday. Progs begin to divert for the later half of the week. GFS lifts a warm front north over the state Thursday night into friday while the ECMWF drops another cold front over the state near the same time period. Both solutions provide an overall drier regime through at least Friday, but the forecast temperatures and pcpn type after Thursday remain in the low confidence level. && .AVIATION...for 06Z TAF Issuance Issued at 845 PM CDT Sat Nov 4 2017 The main aviation forecast issue continues to be visibilities and ceilings overnight. Weak WAA will continue to feed moisture into the region the rest of the evening, but flow will eventually veer southwest with will result in a loss of the low-level lift. Plan to stick close to a consensus of the guidance products which have done pretty well thus far this evening. Expect the IFR/LIFR/VLIFR conditions to persist until mid-morning Sunday, then conditions should improve. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE.........Skowronski SHORT TERM.....MPC LONG TERM......TDH AVIATION.......Skowronski
Area Forecast Discussion...UPDATED
National Weather Service San Joaquin Valley - Hanford CA
809 PM PDT Sat Nov 4 2017 .SYNOPSIS... Weakening cold front will move through the area overnight. Light precipitation is expected into Sunday morning. Clearing and drier conditions are expected through next week. A cold front is expected to approach the region on Thursday night bringing another chance of precipitation. Gradual clearing next weekend. && .DISCUSSION... Regional radar and satellite imagery shows a few isolated light showers as the front slides south across CENCAL overnight. HRRR and new NAM12 guidance is dry across most of the area with clouds and a few isolated showers in the Sierra overnight into Sunday morning. We have cancelled the Winter Storm Warning and lowered POPS and QPF. Temps are looking good at this time and we are not seeing any issues with the wind forecast. && .PREV DISCUSSION... /issued 403 PM PDT Sat Nov 4 2017/ DISCUSSION... A weakening frontal system continues to slide slowly south, nearing northern portions of our area. Just a few light sprinkles have been detected so far across the central California interior today. Precipitation along the frontal zone has been decreasing over time as the front gradually weakens. Short-range hi-res models illustrate this trend, maintaining mainly light precipitation across the area, though still at least some locally moderate snowfall accumulations in the higher elevations around the Yosemite vicinity. With travel impacts still possible in this area, the winter weather highlight for there continues. Models continue to generally wash out the front as it moves through the region tonight. Just some light upslope showers lingering in the south end through Sunday evening in continued cyclonic flow. Dry and warming conditions are then progged into Wednesday under shortwave ridging with temperatures climbing to around climo. Models are coming in better agreement with the next low pressure system approaching from the Northeast Pacific Thursday. Models have not been consistent with the timing and intensity of this system, but it looks like another chance for showers spreading south across the area Thursday with a few showers lingering into Friday. At this time, confidence in precipitation amounts is low, but snow levels look like they will be above 8000 feet. Timing and precipitation amounts with this system will be further refined with additional model runs. && .AVIATION... Areas of MVFR can be expected in the foothills and higher elevations of the Sierra during the next 24 hours with local IFR and mountain obscurations in precipitation. VFR conditions will prevail elsewhere across the central California interior through 12z Sunday. && .AIR QUALITY ISSUES... None. && .CERTAINTY... The level of certainty for days 1 and 2 is medium. The level of certainty for days 3 through 7 is high. Certainty levels include low...medium...and high. Please visit for additional information an/or to provide feedback. && .HNX Watches/Warnings/Advisories... NONE. && $$ public...JDB avn/fw...MV prev discussion...JEB synopsis...JDB
Area Forecast Discussion
National Weather Service Marquette MI
743 PM EDT Sat Nov 4 2017 .SHORT TERM...(This evening through Sunday) Issued at 329 PM EDT SAT NOV 4 2017 Water vapor imagery and RAP analysis show a trof over sw Canada into the nw CONUS with a rather vigorous looking shortwave over southern Saskatchewan. Downstream, wsw flow extends toward the Upper Great Lakes. Shortwave that aided snowfall last night/early this morning is tracking across Lower MI. Pcpn associated with that feature has departed, leaving behind low clouds and some spotty -dz/-ra across the fcst area. During the short term, attention turns to the shortwave currently over southern Saskatchewan. This wave will track ene, reaching northern Ontario on Sun with associated cold front crossing the fcst area during the morning thru mid aftn. Persistent waa/isentropic ascent ahead of the shortwave should maintain some spotty -ra/-dz tonight. Where se winds veering s are upsloping across central Upper MI, fog may become locally dense. Deepening moisture profile and some increase of deep layer forcing should support a modest increase in -ra coverage from w to e late tonight/Sun morning along/ahead of the cold front as it sweeps across the area. As was the case yesterday, it appears roughly the nw half of the fcst area will see best coverage of -ra under more favorable positioning of the upper jet. Pcpn will quickly end with fropa, though there is some question as to whether there will be enough lingering low-level moisture within post-frontal upslope wnw flow to produce some light pcpn over the w. With a steady drop in sfc dwpts behind front this aftn over the western Dakotas and points w per sfc obs along with rather vigorous caa to weaken/lift inversion, don`t think there will be any upslope pcpn across the w as some model guidance indicates. By 00z, 850mb temps will be down to -8 to -10C over western Lake Superior, providing a lake-850mb delta-T of at least 15C. While this would be sufficient to begin LES, inverted-V temp/dwpt profile in the boundary layer by that time along with shallow cloud depth per fcst soundings suggests LES is unlikely to develop before 00z Mon. Temps tonight will remain steady or perhaps rise a degree or two. Temps over the e should reach the mid 40s on Sun prior to fropa while temps over the w will fall from morning highs in the mid/upper 30s. .LONG TERM...(Sunday night through Saturday) Issued at 315 PM EDT SAT NOV 4 2017 Overall, there will be chances for lake effect snow showers, primarily in the west wind snow belts, and cooler than normal temperatures through the first half of the week. Towards the middle/end of next week, the upper-level pattern becomes more active across the region as flow becomes more progressive across the CONUS. Monday and Tuesday: Primarily zonal flow across the Upper Great Lakes will keep us predominately in west-northwesterly flow. This will promote below normal temperatures with lake effect snow chances beginning early Monday and lingering through Tuesday in the west and northwest wind snow belts. Tuesday night through early parts of next weekend: Tuesday night into Wednesday, 850mb temperatures will warm in response to a shortwave digging south across the Upper Great Lakes. This should allow lingering lake effect snow to diminish; however, a trailing cold front associated with a low pressure system progged to track towards/across the Hudson Bay area will drop south across the area Wednesday into Thursday. There is quite a bit of uncertainty across the medium-range models in regards to the strength the system, and thus the colder air behind this system and overall track of post- frontal high pressure. Therefore, confidence in how precipitation chances will unfold, along with temperatures, late Wednesday through Thursday are low. The ECMWF is much stronger with this system, thus allowing for a stronger post-frontal surface high and the potential for some of the coldest temperatures of the season. Whereas, the GFS continues to revert back towards its warmer, less amplified solution advertised a few days ago, which would keep our temperatures more seasonal. The Canadian is similar to the GFS; therefore, tending to lean towards the GFS/Canadian solutions at this time. Friday through Saturday, all of the medium-range models are advertising another shortwave trough tracking across the Upper Great Lakes. However, they diverge fairly significantly in regards to the strength of the upper-level energy, and thus the timing and track of its associated surface low. Given the highly amplified pattern suggested by the ECMWF, it is much slower with the arrival of this system. The GFS essentially splits the difference between the faster Canadian and slow ECMWF solutions. Even though there is considerable uncertainty, it does look like at least some locations across Upper Michigan should see additional precipitation chances to round out the week. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 734 PM EDT SAT NOV 4 2017 Conditions in low stratus will remain at airfield landing minimums at KSAW through much of tonight. IFR conditions will mostly prevail at KIWD and KCMX thru tonight. Some -ra/-dz is expected at times with an increasing chance of rain at the western TAF sites overnight. Passage of a cold front Sun morning will result in improving conditions to MVFR at all terminals. The post- frontal westerly winds will become gusty to at least 25kt at KCMX. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 329 PM EDT SAT NOV 4 2017 Ahead of an approaching cold front, expect se to s winds of generally 20-30kt across Lake Superior tonight. There may be a few gale force gusts to 35kt over eastern Lake Superior this evening. Cold front will sweep across the area late tonight/Sun. In its wake, expect w to nw winds up to 30kt across much of Lake Superior with a few hrs of gale force gusts possible late aftn/evening across the e half of the lake. Mon/Tue, winds will be mostly in the 15-25kt range, though there will be a period of lighter winds for part of Tue. Winds will increase back to mostly 20-30kt Tue night thru Thu. Could be a period of gales for portions of Wed/Thu ahead of and in the wake of a cold front that passes. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...Rolfson LONG TERM...Ritzman AVIATION...Voss MARINE...Rolfson
Area Forecast Discussion
National Weather Service San Francisco Bay Area
657 PM PDT Sat Nov 4 2017 .SYNOPSIS...A few lingering showers this afternoon as a weak surface cold front passes through the Bay Area. Next front moves into the North Bay Sunday evening with another chance of light rain. The front will fall apart as it reaches the Golden Gate and any rain chances end by sunrise Monday. Dry Monday and Tuesday. Increasing clouds Wednesday with a chance of rain by Wednesday night and Thursday as a stronger front arrives. Long range trends continue to look unsettled, especially from Interstate 80 northward. && of 01:46 PM PDT Saturday...The cold front that moved into the Bay Area last night continues to move slowly southward as it begins to fall apart/wash out. Despite its weakening, lingering showers continue to impact parts of the East and South Bay. Farther north skies are actually clearing with some sunshine over the North Bay. Based on latest trends and most recent run of the HRRR will keep a few lingering showers before completely drying out with clearing overnight. Given the clearing skies up north temperatures will dip into the 30s in some locations by Sunday morning. Much drier conditions are expected on Sunday and trended forecast in the that direction. However, models have been advertising another weak front Sunday afternoon and Sunday night entering the North Bay. There are definitely differences with the GFS and EC remaining drying, but the NAM still holds on to some chances. Therefore, will keep the best chance for the North Bay and only a slight chance south to Santa Cruz. Dry weather returns by Monday afternoon through Tuesday. The break will be short lived as medium range models have been indicating an active pattern midweek with wet weather returning to the Bay Area. 12Z models bring rain back to the North Bay early Wednesday then spreading it southward through the day. Additional rain is expected again on Thursday and possibly into Friday. A lot of fine tuning will be done between now and then, but initial rainfall totals look decent with 0.5-1" for the North Bay and lesser amounts southward for the Wednesday system. && .AVIATION...As of 6:57 PM PDT Saturday...Drier air has arrived in most spots per 24 hour check on dewpoint temps, however residual moisture in the lower levels of the atmosphere is causing BKN-OVC cigs at 2,500-7,000 feet from the South and East Bay areas to the north Central Coast. The 850 mb to 300 mb layer relative humidity will steadily decrease area-wide, reaching 20-30% overnight thus improving outgoing radiative cooling. A patch or two of valley fog is possible by morning, including KSTS IFR is forecast Sunday morning. 925 mb cold air advection will be ongoing with an additional 1C-5C cooling into early Sunday morning before turning neutral during the day Sunday thus a marine inversion is not forecast to return in the near term. However, without the marine inversion it`s still possible cigs temporarily trend toward patchy IFR over the coastal waters and along the immediate coast at times late tonight. The 850 mb 0C isotherm is forecast to reach the Monterey Bay area Sunday, expect a lowering freezing level to near 5,000 feet then modifying temperatures arrive late Sunday into Monday. Vicinity of KSFO...W-NW winds near 15 knots til 04z this evening becoming light W later this evening. Tempo BKN cig 12z-16z Sunday otherwise VFR tonight and Sunday. SFO Bridge Approach...Similar to KSFO. Monterey Bay Terminals...MVFR/VFR cigs tonight, tempo IFR cigs and visibilities are possible by midnight into early Sunday morning. 00z tafs indicate BKN MVFR cigs Sunday with a possibility they trend back to VFR Sunday morning. Boundary layer RH increases again over the Monterey Bay Sunday afternoon and evening. For 06z taf issuance may decide to forecast BKN-OVC cloud coverage through Sunday. 850 mb 0C isotherm arrives Sunday morning thus lowering freezing levels prior to some modification in temps late Sunday into Monday. && of 4:42 PM PDT Saturday...A cold front slowly moving to the south will continue to dissipate through the evening. Behind it, seas will gradually subside through Sunday. A second weak cold front will arrive late on Sunday into Monday. && .MTR WATCHES/WARNINGS/ADVISORIES... .Tngt...None. $$ PUBLIC FORECAST: MM AVIATION: Canepa MARINE: Bell Visit us at Follow us on Facebook, Twitter, and YouTube at:
Area Forecast Discussion
National Weather Service Nashville TN
711 PM CDT Sat Nov 4 2017 .UPDATE... FOR EVENING DISCUSSION. && .DISCUSSION... Went ahead and did an early update to the forecast this evening as some showers are continuing across Hickman, Williamson, and Maury Counties. This activity appears to be forming ahead of a very weak shortwave aloft approaching the Tennessee River per water vapor imagery and latest model data. HRRR suggests this activity will continue for another couple of hours before falling apart, with the rest of the night dry although some patchy fog is anticipated, which could be locally dense in some areas. Added a slight chance pop to all zones through 03Z to account for current showers, and started patchy fog earlier in the evening as dewpoint depressions are already low in western counties. Also tweaked low temperatures for tonight but nothing significant. An unusually warm and windy day for early November is on tap for tomorrow with likely record breaking warmth so get out and enjoy it! && .AVIATION... 00Z TAF DISCUSSION. A couple showers developed at TAF issuance time about 30 miles SW of BNA. These should weaken but could approach BNA very briefly around 0130Z. Otherwise, mostly BKN clouds will gradually become more widespread and lower tonight. MVFR ceilings will become common between 06Z and 09Z...and continue through most of Sunday. Patchy fog also possible at all TAF sites for several hours leading up to sunrise Sunday. Expect light south winds to continue overnight and then increase and become a tad gusty by around 15Z Sunday. Winds will stay up the rest of the day on Sunday as surface pressure gradient tightens in advance of the slow-moving MS/OH Valley cold front. That front should not move into Middle TN until beyond the current TAF cycle... probably Sunday night or Monday. && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION......Shamburger AVIATION........49
Area Forecast Discussion
National Weather Service Phoenix AZ
339 PM MST Sat Nov 4 2017 .SYNOPSIS... The region will remain situated between strong high pressure centered over Mexico and strong low pressure centered near the Pacific Northwest. A series of weak upper disturbances will move across the region during the workweek bringing periods of cloudiness. There will also be a slight chance of showers over higher terrain areas of Arizona on Tuesday. Seasonal high temperatures can be expected the first half next week with a little bit of warming during the latter half of the week. && .DISCUSSION... A band of isolated weak showers that tracked across Maricopa County earlier today has shifted into Gila County early this afternoon but has largely dissipated. Cloud cover has also decreased but a deck of scattered to broken mid cloud persists over much of south-central AZ including metro Phoenix. The slow dissipation of cloudiness may be aided by the approach of the southern end of a system that is mainly tracking far to the north. RAP also indicates a more subtle impulse ahead of that which could be a factor as well. Expect less cloudiness on Sunday but with some subtle cool advection, max temps will not be any warmer than today. On Monday and Tuesday, a weak upper low (currently off the southern California coast within a split in the Westerlies) will weaken and move eastward in response to a much more potent system moving through the far northeast Pacific. Meanwhile, a short wave trough evolving out of the northern Rockies and Great Basin will also acquire a stronger positive tilt, with a glancing influence across the Four Corners and Southwest potentially resulting in a few showers Tuesday (primarily over northern and eastern portions of Arizona). All in all, precipitation chances look quite low throughout the forecast period for our CWA, but increased cloudiness is a good bet on Monday and Tuesday. In the extended period, the large-scale pattern will remain quite progressive, with transient shortwave ridging building across the Southwest into late next week and bringing a minor warming trend. However, the heat will have a hard time building as another upstream system approaches the Western CONUS into next weekend. && .AVIATION... South-Central Arizona including KPHX, KIWA, and KSDL: A lingering batch of shallow mid clouds (bases AOA FL100) will linger through the afternoon before slowly dissipating. Surface winds will maintain a westerly component through the afternoon before trending to typical nocturnal patterns after 06Z. Winds aloft (through most of the troposphere) will remain westerly. Southeast California/Southwest Arizona including KIPL and KBLH: Mostly clear skies will continue the rest of the day and overnight with only some very minor high clouds. Southwest and west surface winds will be favored the rest of the day and evening with some minor gustiness possible (more noticeable over the Imperial Valley this evening). Aviation discussion not updated for amended TAFs. && .FIRE WEATHER... Monday through Friday: Moist westerly flow aloft combined with a weak weather disturbance is expected to keep humidities somewhat elevated across the districts during the Monday-Wednesday period, with even a slight chance for wetting rains over the higher terrain north and east of Phoenix during the late Monday-Wednesday period. Somewhat drier conditions and mainly clear skies to return on Thursday and Friday as weak high pressure moves eastward across the region. Minimum humidities it the 20-35 percent range Monday- Wednesday to fall into the 15-30 percent range on Thursday and Friday, with good overnight recoveries. Near-normal temperatures on Monday and Tuesday to become slightly above normal during the Wednesday-Friday period. && .SPOTTER INFORMATION STATEMENT... Spotters should follow standard reporting procedures. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ Visit us on Facebook, Twitter, and at DISCUSSION...AJ/Rogers AVIATION...AJ FIRE WEATHER...Percha