Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/28/18

Area Forecast Discussion...Updated
National Weather Service Billings MT
843 PM MDT Fri Apr 27 2018 .UPDATE... No changes needed to the going forecast. Convection over KBOI`s area this evening was well-depicted by the HRRR, and was being driven by difluence and jet divergence ahead of the SW OR/N CA Pacific low, and by orographics. Models either dissipate the convection or keep it over ID. HRRR dissipated it. Some convection will redevelop over the western mountains Saturday morning as dynamics move over this area. Forecast has some PoPs over the high peaks of the Beartooths/Absarokas in the morning. These PoPs may need to be expanded if models start showing more QPF. Dry forecast for tonight looked fine. Low-level jet will turn winds in the E to the SE, and increase their speeds a bit overnight. Expect mainly clear skies overnight. Temperatures were in good shape given observed temperature and dew points and expected trends overnight. Arthur && .SHORT TERM...valid for Sat and Sun... Strong high pressure aloft will bring continued dry and warm weather through tomorrow. As ridge axis shifts east, thermal low will move to south central MT, bringing what will be the warmest day yet of 2018 for our western and central cwa, including Billings which should see its first taste of 80 degrees. Sheridan should push the mid 80s. Height falls and backed SW flow aloft will open the door to isolated showers/tstm potential across our western mountains and foothills by late Saturday. Low levels across our west will be dry and well-mixed, and forcing will be weak, so will keep coverage at isolated, though could see some erratic surface wind gusts near any weak storms that develop. Eastern areas will see increasing boundary layer moisture, but air mass will be capped w/ increasing SE winds. Far eastern areas from Baker to Ekalaka will see gusts of 35-45 mph tomorrow. Shortwave and west-to-east passage of a weak cold front will keep the risk of showers going through the night and Sunday morning across the western two-thirds of our forecast area. Latest models are a little more aggressive w/ the surface front, so have expanded pops further east by late Saturday night. Better potential for showers and thunderstorms is Sunday afternoon and evening as a stronger shortwave lifts through WY, ahead of a fairly deep upper low over ID. Likely pops across the region look good and will keep this forecast going. As for the potential for strong storms, eastward passage of surface front will result in NW surface winds and decreased instability across our western and central areas. It looks as if greatest chance of strong storms is in our east in vicinity of surface trof, and this is something to watch as we get closer to Sunday. Shear and instability, along with PV lifting thru WY at a favorable time of day, could support a few severe storms if the surface trof is slow to exit into the Dakotas. Regardless of this, Sunday will be an active day of weather and anyone with outdoor plans should take note. Temps on Sunday will be warmest in our far east, maybe near 80 degrees, and post-frontal/cooler in our west (mid 60s to lower 70s). Chance of precip will continue through Sunday night as upper trof to our west moves slowly east. Freezing levels will fall slowly during this time and elevations above 7kft could see some snow accumulation by early Monday. JKL .LONG TERM...valid for Mon...Tue...Wed...Thu...Fri... An unsettled weather pattern will persist through the middle of the coming week as an upper trough and associated low dominate the weather over the western US. A weak shortwave looks to lift into the region on Monday spreading precipitation across the area Monday into Monday night. While the precipitation looks to remain mainly rain at the lower elevations, snow accumulations across the higher elevations look possible. Heading into Tuesday, general troughiness continues, with models digging a cutoff low over the desert southwest and dropping another shortwave into the area out of the northwest. This will continue shower chances over the area for Tuesday, possibly into Wednesday. Uncertainty remains high for this time frame as models continue to struggle with placement and timing of waves and associated precipitation. High pressure then looks to build over the region Thursday into Friday diminishing shower chances. High temperatures will range from the 50s to lower 60s through midweek with the unsettled weather pattern, potentially warming back into the 70s by Friday as high pressure builds back over the region. Low temperatures in the 30s can be expected most nights/mornings. STP && .AVIATION... Strong high pressure aloft will bring continued VFR flight conditions tonight and Saturday. Southeast winds will increase in far southeast MT, with gusts of 30-40 kts at KBHK tomorrow. Expect isolated showers and thunderstorms across western areas by late Saturday. TWH/JKL && .PRELIMINARY POINT TEMP/POPS... Sat Sun Mon Tue Wed Thu Fri ----------------------------------------------------------- BIL 046/082 053/071 043/056 038/057 037/057 037/063 040/071 00/U 26/T 64/W 33/W 32/W 11/B 11/B LVM 041/080 045/065 037/052 034/054 034/053 032/059 034/066 02/T 35/T 54/W 44/W 33/W 11/B 11/B HDN 042/084 052/074 044/058 038/058 037/059 037/063 040/071 00/U 26/T 75/W 43/W 22/W 11/B 11/B MLS 044/079 052/075 047/058 038/055 036/059 037/062 040/070 00/N 12/T 64/W 33/W 12/W 11/B 11/U 4BQ 043/077 054/075 046/057 039/054 037/056 037/058 039/068 00/N 13/T 64/W 43/W 12/W 21/B 11/U BHK 039/071 048/077 046/060 036/052 033/057 035/059 037/067 00/N 02/T 63/W 33/W 11/B 11/B 11/U SHR 043/083 051/072 042/054 037/054 037/053 034/057 036/065 00/U 26/T 66/W 53/W 23/W 21/B 11/U && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...None. WY...None. && $$
Area Forecast Discussion
National Weather Service Wilmington NC
1045 PM EDT Fri Apr 27 2018 .SYNOPSIS... Weak high pressure will prevail tonight into Sat. A dry cold frontal passage will occur Saturday night, followed by cool Canadian high pressure for Sunday into Monday. The center of the high will drift across the area Tuesday and slowly offshore from the Southeast U.S. Coast during the mid to late week period of next week. This will result in a substantial warm up to occur during the mid to late week period of next week, with continued dry conditions under mainly clear skies. && .NEAR TERM /THROUGH SATURDAY/... As of 830 PM Friday...The sfc based inversion should develop but later this evening or overnight then the usual right after sunset. This due to an active boundary layer. As the sfc pg further relaxes this evening and overnight, winds, especially away from the coast, will eventually decouple. Enough low level moisture remains given current and overnight progged sfc dewpoints. In addition, sfc dewpoint depressions will run 0 to 3 degrees F. All of this is enough to atleast include patchy ground fog for most locations mainly during the pre-dawn Sat hrs. Previous....................................................... As of 300 PM Friday...A beautiful day ongoing across behind this mornings weak low pressure and rain showers. Much drier air advecting overhead noted on WV imagery and evident on visible is combining with weak subsidence and a capping inversion to prevent any showers locally. Despite the HRRR insistence that showers will develop across SE NC this aftn, have kept POP below mentionable as even the Cu field outside looks flat due to dry air entrainment from above. For this reason do not anticipate anything more than maybe 1 isolated shower in Pender County, not worth a POP addition. Otherwise, dry air aloft will eventually win out, and other than some scattered mid-level cloud cover tonight expect mostly clear sky conditions with winds becoming light. As mins fall into the mid and upr 50s, good radiational cooling, light winds, and still a moist ground could support some fog overnight. Text bulletins keep visibility mostly unrestricted, and soundings show only shallow saturation despite favorable low-level hydrolapse rates. Could see some shallow fog overnight, but otherwise do not expect widespread or dense fog. On Saturday, the region enters a warm sector ahead of a cold front which will be on the doorstep Saturday evening. Despite continued broad troughing aloft, WAA on SW winds near the surface will drive temps up towards 80 on Saturday, but have forecast temps slightly below guidance to account for expected diurnal Cu and lowered thicknesses beneath the upper trough, but still a beautiful and dry day forecast for Saturday! && .SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/... As of 300 PM Friday...What a difference a day makes. Although sunshine will be plentiful, Sunday will be much cooler than Saturday. The mid to upper trough will dig down and push a dry cold front through and then finally swing off the coast Sun night. The main shortwave energy will remain north Sat night but should see some passing clouds as front passes through. The pcp water is up to .75 inches Sat night but plummets down to a quarter of an inch or less through Sun. The low level westerly flow will swing around to the NW and N with a dip in 850 temps from 10C Sat eve down near 2C Sun morning. Overall, plenty of cool and dry air will make its way in Sat night into Sun. Temps Sat night will begin to drop in CAA, ending up in the low to mid 50s by daybreak. Late April sunshine will work against the CAA to push temps to near 70, but most of the day will be in the 60s with a cool northerly wind. By Sun night the atmosphere will decouple over most of the area leaving near calm to calm winds overnight. This will combine with clear skies to produce temps down in the 40s most places. && .LONG TERM /MONDAY THROUGH FRIDAY/... As of 300 PM Friday...H5 low over New England will drift farther east during Monday while a ridge axis begins to push east of the MS valley. Overall, this pattern change will result in increasing heights aloft, subsequent warming trend, and a continued lack of support for rainfall. Additional height increases are likely the latter half of the week as a subtropical high builds across the northeast Gulf of Mexico and ridges across the southeastern United States. The precipitable water will only be a half inch or less Monday and Tuesday, gradually increasing to around 1 inch by Friday. While the long term period will start below normal on Monday look for temperatures to get back above normal by Tuesday and each day thereafter through Friday. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... As of 00Z...Mostly VFR conditions expected through the forecast period. With good radiational conditions developing overnight, there is always the threat of MVFR BR. With most guidance pointing to this, I did use prevailing groups for all sites for a couple of hours during the early morning. A little longer for CRE. Extended outlook...VFR. && .MARINE... NEAR TERM /THROUGH SATURDAY/... As of 830 PM Friday...Based on latest buoy reports and trends, included SW gusts up to 20 kt during this evening and then followed previous fcst dropping it back down to the West at 10 kt or less. Significant seas have kept widespread 2 to 3 ft for the overnight with some 4 footers off Cape Fear via latest 41013 reports. These 4 footers will become less apparent as the wind driven wave portions of the seas subsides as previously mentioned. The ESE-SE, 8 to 9 second period swell will continue to very slowly subside but remain the dominant input to the seas. Previous....................................................... As of 300 PM Friday...SW winds will persist across the waters through this evening at 10-15 kts, before easing and veering to the west late as a weak trough pushes offshore. Winds will return to the SW Saturday as flow around the high pressure offshore and ahead of an approaching cold front reaches 10-15 kts, with slightly higher gusts likely within the near shore sea breeze during the aftn. The front will still be well west of the waters by the end of the period so SW winds will persist into Saturday night. A slowly decaying SW wind wave and 8-9 sec 2 ft SE swell will combine through the period to produce the wave spectrum this period. Seas currently of 3-4 ft will fall slowly to around 2 ft late as the wind wave contribution eases. SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/... As of 300 PM Friday...Seas will drop to less than 3 ft through Sat eve in a lighter SW to W flow but a cold front will move through overnight. Winds will swing around to the north behind the front, increasing up to 15 to 20 kts through daybreak Sun. Seas will increase to 3 to 4 ft Sunday morning. The slight surge in northerly winds will diminish through late Sun leaving a NW to N wind around 10 kts. This will allow seas to drop to less than 3 ft by Sun night. LONG TERM /MONDAY THROUGH WEDNESDAY/... As of 3 PM Friday...High pressure will build over the waters during Monday with a period of light and variable winds. The high will be positioned off the SC coast Tuesday through Wednesday with light southwesterly flow prevailing. No issues with seas as they remain 3 ft or less through the period. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...DCH NEAR TERM...DCH/JDW SHORT TERM...RGZ LONG TERM...SRP AVIATION...SHK
Area Forecast Discussion
National Weather Service Lincoln IL
856 PM CDT Fri Apr 27 2018 .UPDATE... Issued at 856 PM CDT Fri Apr 27 2018 Skies remain partly to mostly cloudy this evening and as the cold front and associated light showers/virga continues to move southeast across the CWA. Winds have also started to subside and gusts are fewer and speeds are less. Current forecast has good handle on this so far. Only concern is overnight low temps across the area. Dwpts are in the 30s across the area, but winds of 10-15 mph should keep things mixed enough that overnight lows should not fall down to dwpts. Current forecast lows of upper 30s to lower 40s looks fine. Since forecast is handling current trends good, will not be updating at this time. && .SHORT TERM...(This evening through Saturday) ISSUED AT 250 PM CDT Fri Apr 27 2018 High-based CU field is becoming more robust along an advancing cold front across eastern Iowa/northern Illinois this afternoon. Despite developing radar echoes, have not yet seen any reports of precip reaching the ground. Cloud bases are generally around 10,000ft...similar to what 12z forecast soundings showed. High-res models such as the HRRR have been consistently suggesting widely scattered showers developing along the front late this afternoon into the evening, and based on current satellite/radar trends, have no reason to doubt that. Given the very dry airmass below 800mb, any showers that develop will have the capability of bringing higher momentum air down to the surface via evaporative cooling...potentially producing wind gusts of 30-35mph. Have included slight chance PoPs along/north of a Canton to Bloomington line late this afternoon...then as far south as I-70 this evening before the showers completely dissipate after sunset. The cold front will settle southward into the Ohio River Valley late tonight, allowing a chilly airmass to settle into the region. Low temperatures tonight will range from the upper 30s the middle 40s far south around Lawrenceville. Highs on Saturday will generally remain in the middle to upper 50s. .LONG TERM...(Saturday night through Friday) ISSUED AT 250 PM CDT Fri Apr 27 2018 As has been advertised for the past few days, the coldest period of the entire forecast will be coming up Saturday night as a 1028mb high builds into Illinois. Winds will become light/variable and skies will be clear, allowing excellent radiational cooling conditions to develop. Resulting low temperatures will bottom out in the lower to middle 30s, with areas of frost likely developing. If trends continue, a Frost Advisory will eventually be needed for parts or all of the KILX CWA Saturday night into early Sunday morning. After one more cool day on Sunday, high pressure will shift east of the region and southerly winds will bring a marked warming trend next week. High temperatures will soar well into the 70s on Monday...then will climb into the upper 70s and lower 80s by Tuesday and Wednesday. Meanwhile, a deep upper trough will dig across the western CONUS...then will slowly begin ejecting eastward as the week progresses. Latest trends suggest this process will take place in several phases and will be slightly slower than previously thought. The first wave and its associated rain chances will arrive Tuesday night into Wednesday: however, model consensus suggests that the best rain chances will hold off until Thursday/Thursday night as a significant portion of the western trough pushes eastward into the Midwest. Have therefore kept PoPs in the chance category through Wednesday...before increasing to high chance/likely late Wednesday night through Thursday night. After that, a cold front will slowly settle into the Ohio River Valley by Friday, shifting the best rain chances off to the E/SE at that time. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 630 PM CDT Fri Apr 27 2018 VFR conditions will prevail at all TAF sites next 24hrs. Broken AC around 8-9kft will move across the sites this evening, ending first at PIA, then BMI and then around 4z at SPI/DEC/CMI. Then clear skies to scattered clouds expected remainder of the night and into the early morning hours. Then scattered AC around 10kft will move back into the area during the morning hours and will continue into the afternoon. Winds will be quite gusty this evening with possible showers so have higher winds gusting to over 25kts this evening with VCSH. Once showers moves out and sunsets, winds will decrease some out of the northwest. Winds become northerly tomorrow but with speeds of only 10-15kts. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Auten SHORT TERM...Barnes LONG TERM...Barnes AVIATION...Auten
Area Forecast Discussion
National Weather Service Mount Holly NJ
929 PM EDT Fri Apr 27 2018 .SYNOPSIS... Several low pressure systems will move into the northeast this weekend and combine into one and remain across New England through early next week. A cold front is expected Saturday, with additional surface troughs Sunday into Tuesday. High pressure across the Mid Mississippi and Ohio Valley Sunday will build to our south Monday, before shifting offshore of the Carolinas Monday night where it remains through Thursday of next week. A cold front is forecast to approach the east coast next Friday. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... With the 930 PM update, made some adjustments to weather and PoP for later tonight. The area of showers and thunderstorms in central PA continues to show organization in two separate lines. It should weaken some as it gets closer to our area; much of our area did not clear out before sunset, therefore, we are starting out with lower temperatures as compared to central PA and thus lower instability. None the less, there is some elevated instability in RAP model soundings at 06Z enough to support isolated thunderstorms. These showers are associated with a leading mid and upper level short wave trough that is expected to lift northeast over PA overnight. The wind should become light and variable overnight as the weak surface low departs our region. The lingering low level moisture is expected to manifest itself in the form of low clouds and areas of fog. We did see some clearing, though low clouds are starting to build back in. If this trend continues, this could be more of a low stratus event, but given dew point depressions already less than 5 degrees F for many sites, did not have enough confidence to reduce the mention of fog across the area. Minimum temperatures are forecast to range from the middle 40s to the lower 50s in much of southeastern Pennsylvania, New Jersey, Delaware and northeastern Maryland. Lows should be in the lower 40s in the Poconos and in far northern New Jersey. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/... The sky should become mostly sunny over much of our region on Saturday morning after any lingering low clouds and fog lift and dissipate. However, clouds should be on the increase again during the afternoon as a cold front approaches from the west. The wind is expected to be from the southwest around 10 mph. The cold front is forecast to begin moving into eastern Pennsylvania toward evening. We have mentioned the potential for rain showers as the boundary nears. The southwest flow should result in slightly above normal daytime temperatures. Highs will favor the upper 60s and lower 70s in much of our region. Readings should not get above the lower and middle 60s in the elevated terrain up north. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... On Sunday high pressure will be moving out of the Mid Mississippi Valley and across the Tennessee River Valley, before shifting across the southern Applachians and offshore of the Carolinas Monday. Meanwhile, low pressure will remain across New England. This will keep our area under the influence of a west to northwest flow, with a couple of weak surface troughs and short wave/vorticity impulses moving across the area both Sunday and Monday. Most of the area will remain dry with the passage of the surface troughs. However, an area of enhanced low-mid moisture will slide across portions of northeast Pennsylvania and northern New Jersey, which could lead to a chance of isolated showers. Gusty conditions are expected to develop both Sunday and Monday with winds gusting 20-30 mph at times. The high will remain to our south Tuesday into Wednesday, keeping dry conditions in the forecast. Winds could remain gusty at times, but likely not as gusty as Sunday or Monday; generally 15-25 mph. Late in the week a cold front is expected to move toward the area from the west. Right now it looks like the front will not make it fully into the area Thursday, but more likely Friday. There will be a chance of isolated showers starting Wednesday night through Friday as multiple short wave/vorticity impulses will be sliding across the area. However, the most likely period for showers is Friday with the passage of the actual cold front. After an up and down forecast to the temperatures Saturday and Sunday, a warming trend will begin Monday and continue through the upcoming week. Temperatures in the 80s are forecast for the end of the week from Wednesday through Friday. && .AVIATION /02Z SATURDAY THROUGH WEDNESDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Tonight...High confidence that the wind will be light and variable through the overnight period. However, for the remainder of the forecast elements, have low confidence. First, ceilings will be between MVFR and VFR through the evening hours. Timing of changes between MVFR and VFR is uncertain. After midnight, expect a round of fog and possibly low clouds to lower conditions to IFR at most places, though LIFR is also possible. May have a better idea in the next few hours as we monitor temperature and dew point trends after sunset. Saturday...VFR after early morning low clouds and fog. Southwest wind 6 to 10 knots. Showers arriving from the west very late in the afternoon. Moderate confidence in most aspects of the forecast, but low confidence in the return to VFR conditions. OUTLOOK... Saturday night-Wednesday...VFR. Gusty west to northwest winds 20-25 knots Sunday and Monday. Gusty west to southwest winds 15-20 knots Tuesday and Wednesday. && .MARINE... Winds and seas are expected to remain below small craft advisory conditions tonight and Saturday. A cold front is forecast to approach from the west on Saturday. Wind speeds are expected to remain less than 15 knots with gusts not exceeding 20 knots. OUTLOOK... Saturday night...Conditions expected to remain below advisory levels. Sunday-Monday...Winds may approach Small Craft Advisory levels on Sunday into Monday. Monday night-Wednesday...Conditions expected to remain below advisory levels. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...None. && $$ Synopsis...Robertson Near Term...Iovino/Johnson Short Term...Iovino Long Term...Robertson Aviation...Iovino/Johnson/Robertson Marine...Iovino/Johnson/Robertson
Area Forecast Discussion
National Weather Service Pocatello ID
206 PM MDT Fri Apr 27 2018 .SHORT TERM...Tonight through Monday afternoon. Low pressure disturbance to our west has a embedded disturbance rotating through California and Nevada, part of which may sneak into southern Idaho late this afternoon and this evening with a slight chance of thunderstorms that could move into the Sawtooth Mountains. The GFS and the RAP both have an indication of some limited moisture after midnight tonight moving towards Pocatello and then onto Palisades by Saturday morning. Looks like high level moisture and late hour so chose to not include any showers with that patch of clouds. The high pressure ridge slips east as the low moves inland, we remain under southerly flow and should stay on the warm side, a little more cloud cover and cooler air aloft. Late Saturday afternoon and evening we could fall under the influence of a spoke of energy rotating around that low. Kept a slight chance of thunderstorms in the forecast for the Central Mountains, Snake Plain, and Eastern Highlands as it is real hard to pin point the activity. Overnight Saturday and through Sunday, the bulk of the disturbance moves across Idaho. Moisture deepens and even snow levels drop by Sunday to near 6000 feet, then rebounds by afternoon with highs in the 50s. Best snow should be in the Central Mountains with 1 to 4 inches possible and most of that on the upper elevations. What ever shows up below 7000 feet will not last long. RS .LONG TERM...Monday night through Friday. Showers continue into Tuesday as a trough remains over the state, with a new low carving itself out to our southwest. At this point, trying to get into details would be futile as the amount of showers and precipitation varies among the models. It will remain pretty cool across the board with snow levels in the general 6000-7000ft range. The low shifts east on Wednesday, but close enough to keep showers going with a better chance east of I-15. Confidence is low enough right now to not go terribly high with the chance of rain or snow. That storm will finally move far enough east by the end of next week to dry things out PERHAPS. The ECMWF wants to set up a stronger blocking pattern over the West, keeping us dry by then. The GFS has a ridge but weaker in comparison and allows limited moisture for a few showers and thunderstorms. We followed with a blended forecast that keeps isolated development over the central mountains and along the Montana border. Keyes && .AVIATION...The question over the next 24 hours is how extensive will shower and thunderstorm coverage will be across eastern Idaho. Higher resolution models seem to indicate that any real threat will be isolated tonight from around Twin Falls through the central mountains. There MIGHT be a few showers/storms that develop farther east but that could be stretching it, and we end up with just some mid level clouds. We did keep VCTS for a few hours this evening at KSUN based on current trends. We DON`T have it for any other TAF sites but that could change based on what happens this evening and tonight. For Saturday, it looks like there are two potential areas for showers and storms with a dry slot over the Snake Plain. The first is over the central mountains to south of KBYI. At the moment, it looks like VCTS would be warranted in the afternoon at KBYI and potentially KSUN. For the latter, trends point toward most of this staying to the north and west. Therefore, we left it out...for now. The other area would be in the eastern highlands, affecting KDIJ at some point for at least VCTS. We have dry air in place at the surface, so we are looking at a potential gusty wind threat through tomorrow with convection. Otherwise, VFR weather is anticipated. Keyes && .PIH WATCHES/WARNINGS/ADVISORIES...None. && $$
Area Forecast Discussion
National Weather Service Phoenix AZ
855 PM MST Fri Apr 27 2018 .SYNOPSIS... Very warm conditions will continue through the weekend with widespread high temperatures in the mid to upper 90s at lower elevations. A slight chance for thunderstorms will exist across southern Gila County on Friday and Saturday afternoon, but most locations will not see measurable rainfall. A distinct cooling trend will occur for at least the first half of next week, with a slight chance of showers possible on Tuesday into early Wednesday morning. Breezy winds will be possible on Sunday and Monday, with stronger wind gusts on Tuesday. && .DISCUSSION... At 8 pm this evening, a large upper low could be seen spinning just off the Pacific northwest coast allowing the high pressure ridge over the desert southwest to shift east; 00z plot data showed the ridge axis near the New Mexico border. Ahead of the approaching low, dry southwest flow aloft was spreading into the western deserts and IR imagery showed generally clear skies from Phoenix west into far SE CA. East of Phoenix, flow was more south/southeast and modest amounts of mid level moisture had advected into the higher terrain allowing high based cumulus to form over portions of southern Gila county as well as the eastern mountains. So far no high based storms or lightning strikes were noted over the high terrain east of Phoenix despite the modest mid level instability present. High temp today in Phoenix reached 100 degrees under sunny skies and this should be the last day where high temperatures threaten the triple digit mark; the low to our west will gradually push inland and drop heights leading to a substantial cooling trend that will eventually drop deserts highs to around 80 by the early to middle part of next week. For the rest of tonight expect the clouds to our east to continue to dissipate while skies remain genly clear from Phoenix westward. Current forecasts look to be in good shape and no updates are needed. .PREVIOUS DISCUSSION... Temperatures have once again climbed into the 90s for most areas with a few spots in the Colorado River valley near 100 degrees as Central Arizona and southeast California remains under a mid-to- upper level ridge of high pressure. Some parts of Phoenix will reach 100 today as skies continue to remain clear with relatively strong subsidence. Clouds continue to develop over the higher terrain in Gila County where cooler temperatures generally in the 80s are in place along a dissipating back door cold front. Additional daytime heating and increasing MUCAPE values above 100 J/kg may allow for a few isolated thunderstorms to develop there late this afternoon into the evening hours, but most hi-res models including the HRRR keep this activity well northeast or just south of our area. Any thunderstorm that does develop will most likely not produce measurable rainfall, but there is a threat of lightning that could initiate wildfires. Thunderstorm chances still appear to peak tomorrow afternoon for locations northeast of our region, but most hi-res models suggest this activity will be northeast of Gila County. However, global models continue to suggest the potential for measurable QPF over far northeast Gila County, and MUCAPE values will be a little higher tomorrow with greater moisture in place. Thus, we have retained the mention of thunderstorms over this area, with the biggest hazard remaining lightning strikes with a low chance of measurable rainfall. Temperatures tomorrow may be a little cooler tomorrow with this slight increase in moisture, but a more substantial 3-5 degree cooling will occur on Sunday as the ridge weakens further and heights fall ahead of a slowly digging trough centered over the Pacific Northwest. Temperatures will decrease to near or slightly below normal by Monday as a vorticity maximum breaks off and rapidly digs along the California coast and a dissipating front moves into western Arizona. Global models show this low becoming cutoff along the southern CA-AZ border on Tuesday, with dynamic forcing associated with this cold core possibly triggering isolated thunderstorms over higher terrain in southeast California. This trough should lift northeast over Arizona Tuesday night into Wednesday morning, which should allow for some shower activity at higher elevations with perhaps some isolated showers into the I-10 corridor as weak SW-NE isentropic ascent overspreads the region. Thus, we have increased POPs closer to 15-20 percent for the Phoenix metro with 20-30 POPs further northeast and below 10 percent further west. This forecast is dependent on the low tracking directly over or just west of the region with enough moisture aloft, with an eastward deviation making measurable rainfall more unlikely. At the current moment, we only have a few hundredths of an inch of rain well northeast of the Phoenix metro, but models trending even cooler continues to look more likely. Breezy winds will be possible on Sunday and Monday, with stronger wind gusts in excess of 30 mph at higher elevations possible on Tuesday mainly due to dynamic forcing from the low. Temperatures for Tuesday and Wednesday were decreased a few degrees from the previous forecast. Temperatures are close to the previous forecast for the second half of next week as the model ensemble exhibits considerable spread in whether or not a more progressive pattern will occur or additional shortwaves will break off from the main flow and push through the region. For now, we sided with the more progressive pattern shown by the GFS, leading to a fairly rapid warmup in temperatures closer to climatological normals. && .AVIATION... South-Central Arizona including KPHX, KIWA, and KSDL: Expect skies in the greater Phoenix area to remain genly clear until Saturday afternoon when another round of high-baed cumulus will develop over the higher terrain off to our east. Should any storms develop over the mountains tomorrow afternoon/evening, we do not expect any outflow winds or dust to reach into the Phoenix area or affect the terminals. Winds next 24 hours will follow typical diurnal tendencies, with potential for some afternoon southwest gusts tomorrow reaching into the teens or low 20s. Southeast California/Southwest Arizona including KIPL and KBLH: Upper low approaching from the west will provide dry southwest flow aloft and result in genly clear skies through Saturday evening. Expect winds to favor the west at KIPL next 24 hours, with gusts to around 25kt thru midnight tonight and again tomorrow late afternoon and evening. Winds to favor the south to southwest at KBLH with some gusts also expected Saturday afternoon. Do not expect any blowing dust with the gustiness. Aviation Discussion not updated for amended TAFs. && .FIRE WEATHER... Monday through Friday: Breezy to windy conditions will impact the districts Monday and Tuesday with the strongest gusty winds of 20 to 35 mph Tuesday afternoon. Cooler than average temperatures along with modestly increased moisture values will keep humidity values elevated slightly above critical thresholds. Afternoon minimum humidity values will generally fall in a 15 to 25% range during the first half of the week, falling to a 10-15% range by the end of the week. Overnight recovery will generally be good. Wind speeds will decrease substantially later in the week as temperatures warm back up near and above the seasonal normal. && .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to follow standard reporting procedures. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ DISCUSSION...CB PREVIOUS DISCUSSION...Deemer AVIATION...CB FIRE WEATHER...AJ