Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 08/10/12


AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1149 PM EDT THU AUG 09 2012 .Forecast Update... Issued at 1145 PM EDT Thu Aug 9 2012 Updated the forecast to adjust POPs a bit. The 0Z NAM seems to have the best handle on convection this evening. Convection over central IN right around the sfc low should continue to move east over the next 2-4 hrs and may develop a bit further south into our southern Indiana counties. However, these storms should struggle to reach severe levels given the lack of forcing further removed from the front and main upper level wave as well as lack of instability due to storms early this evening. The next area of focus looks to be southern IL as wind shear profiles increase with the upper shortwave dropping south through IL and into western KY through the early morning hours. SPC mesoanalysis indicates good moisture convergence along the sfc front over southern IL with some isld-sct cells noted over western IL to southeast MO. DCAPE values are at a relative max over southern IL and western KY. Would expect new convection to develop over southern IL over the next 2-4 hours, initially push SSE, and then pivot more easterly into our area during the pre-dawn hours and as the shortwave pivots aloft. This will probably be our best chance for strong to severe convection overnight. Forecast confidence in this occurring is low to medium given model inconsistencies and banking on convection developing over southern IL. && .Short Term (Tonight through Friday Night)... Issued at 331 PM EDT Thu Aug 9 2012 ...Active Period of Weather Expected This Afternoon and Tonight... Fairly active period of weather is shaping up for the Ohio Valley this afternoon and tonight. In the near term, mid-level shortwave combined with surface temperatures hitting convective temperatures has resulted in convection firing across the region. Several areas of convection are occurring across the area. The first is an organizing line near the I-75 corridor in our eastern sections. This is being forced by the aforementioned mid-level wave and by diurnal heating. This activity will continue to head east and into WFO JKL`s area over the next hour or so. Further west, a well defined residual outflow boundary was located along our border with WFO IND. This boundary extends from northern Dubois county NE to Jefferson County. Convection is firing along this boundary due to strong moisture convergence and diurnal heating. This activity should head east-southeast over the next few hours. Finally additional convection is firing also over west KY. Based on the latest runs of the LMK WRF and 4km HRRR runs, this activity should also head east-southeast and may impact our far southwestern counties later this afternoon. Based on RUC proximity soundings, this afternoon`s convective activity is likely to remain in the pulse variety with damaging winds, torrential rains and intense CG lightning being the main threats. Latest deterministic and ensemble model runs seem to be showing some forecast convergence with the forecast for later this evening and overnight. First mid-level trough will scoot east this evening while a secondary and more potent mid-level trough dropping down into the Ohio Valley late tonight. As this wave drops south, surface cyclone near KSTL will shift northeast while associated surface cold drags behind. Strong mid-level height falls will result in widespread synoptic scale lift across the region late tonight. This combined with forcing along the front should result in a secondary line of convection developing to our northwest and slide southeast overnight. Despite this line moving through during an instability minimum, the upper level dynamics appear to be strong enough to support convection despite the meager instability. Current thinking is that a convective line will generate along the I-70 corridor and then drop southeast overnight. The line will likely be strong to possibly severe especially to our northwest. However, as the line heads southeast, it is possible that line may weaken a bit as it slides through KY. Convection should be pushing through southern Indiana in the 04-06Z time frame and then through KY in the 06-11Z time frame. Have gone ahead and bumped up PoPs for the overnight period. Lows will remain mild with temperatures falling into the lower-mid 60s in the northwest and mid-upper 60s elsewhere. For Friday, the main forecast change here is that a lot more cloud cover will be likely during the morning hours. Latest model time-height model cross sections show plenty of low-level moisture lingering behind the frontal boundary as it pushes through. Thus, mostly cloudy skies seem very likely in the morning followed by progressive clearing during the afternoon and into the evening hours. Highs tomorrow will be quite cool compared to what we`ve seen over the last few months. We should see readings in the upper 70s in the east with upper 70s to lower 80s in the central and west. Lows Friday night will be quite comfortable with lows in the mid-upper 50s. .Long Term (Saturday through Thursday)... Issued at 315 PM EDT Thu Aug 9 2012 ...Mostly Sunny, Dry, and Cool Weekend Ahead... A vertically stacked unseasonably far south and strong closed low will begin to slowly fill over Lake Huron Saturday. This system will slowly weaken and slowly lift north towards St. James Bay by late Sunday. In its wake, it will leave residual troughing across the western Great Lakes and the upper Midwest. By early Saturday, the occluded front related to this upper low will already have moved well east of the Commonwealth. Much drier and cooler air originating in Canada, will have overspread the state by dawn Saturday. Expect mostly clear skies and relatively cool temperatures for the upcoming weekend. Dewpoints will likely fall into the lower 50s by Saturday afternoon. Highs will struggle to exceed 80 on Saturday with highs on Sunday warming just a few degrees into the lower 80s. Overnight lows early Sunday will quite likely reach into the upper 50s, with perhaps our urban areas remaining near 60. A broad longwave trough will remain centered roughly over the Great Lakes during the early portion of next week. This will ensure no repeat of the excessively hot temperatures of early August anytime soon. Both the latest GFS and the ECMWF show a disturbance sliding southeast towards the base of this longwave trough Monday and Tuesday. This system will approach the Commonwealth by late Monday. At the surface, this system will likely aid in the formation of a weak surface trough that may serve as a focus for convection beginning late Monday, possibly continuing through the bulk of Tuesday. Will introduce a chance of storms for the later half of Monday, extending through Tuesday. Temperatures will warm a bit within the Monday through Thursday time period. However, even by Wednesday through Friday, temperatures will not exceed our seasonal mid-August averages with highs remaining in the upper 80s to around 90 && .Aviation (00Z TAF issuance)... Issued at 709 PM EDT Thu Aug 9 2012 Convection continues across the forecast area this evening. An east-west outflow boundary is roughly located along I-64 in southern Indiana and Kentucky. Two areas of convection are located along this boundary...the western cluster is centered over near KHNB while the eastern one is located northeast of KLEX. In general, convection should wind down temporarily over the next few hours as instability wanes. The terminals should generally see VFR conditions this evening. Secondary upper level wave and associated cold front are currently located to our northwest up north of I-70. Regional radars show an expanding area of convection across central IL and IN. This convection is progged to move east-southeast and will affect primarily the KSDF and KLEX terminals later tonight...most likely after 10/04Z. Convection reaching the KBWG area is much more uncertain as many of the 18Z numerical model runs weaken the line of convection as it heads through KY. For now have gone a little more optimistic at KBWG and plan on carrying only VCTS for the overnight period. It still looks like we`ll have plenty of low clouds in the morning with low end MVFR cigs during the morning hours. Progressive clearing looks to take place after 10/15Z. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...NONE. KY...NONE. $$ Update...........AMS Short Term.......MJ Long Term........JSD Aviation.........MJ
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
850 PM EDT THU AUG 09 2012 .Forecast Update... Issued at 845 PM EDT Thu Aug 9 2012 Convection across the area has decreased in intensity for now. However, steady rains with an occasional t-storm continue over Dubois County, IN in the Huntingburg area. Although no flooding has been reported from sources in that area, this could be a location to watch overnight for flooding issues along with other areas over southern Indiana and the Bluegrass that had flood advisories/warnings out earlier this evening. As for convection tonight, the main upper low was pushing south into the upper Midwest as of 0Z with a sfc cold front stretching from west central IN to southeast MO to northern TX. A strengthening sfc low was noted across west central IN where the strongest convection has been firing over the last few hours. The sfc low is still progged to strengthen and move northeast overnight with the cold front push ESE into our area after midnight. Ongoing convection to our NW should move into our area after midnight according the local LMKARW model which is handling convection the best today. However, strength of that convection is in question due to earlier t-storms over the area. Convection may become more elevated has it gets into southern Indiana where a shallow stable layer and less atmospheric instability exist. However, some portions of central KY that did not receive convection this evening are still unstable with effective 30-40 kt shear and good moisture convergence noted over western KY. Another factor to consider in the equation is the strength of the overall synoptic system which is impressive for this time of year and we will be seeing better bulk shear values move into our area later tonight as the sfc front and trough move through the region. Therefore cannot rule out strong to severe storms for late tonight, however, conditions look less favorable in areas that saw storms this evening. Will continue to monitor upstream trends this evening and adjust the forecast as necessary. Prime time for storms tonight would be after midnight through about 8 am EDT across our area. && .Short Term (Tonight through Friday Night)... Issued at 331 PM EDT Thu Aug 9 2012 ...Active Period of Weather Expected This Afternoon and Tonight... Fairly active period of weather is shaping up for the Ohio Valley this afternoon and tonight. In the near term, mid-level shortwave combined with surface temperatures hitting convective temperatures has resulted in convection firing across the region. Several areas of convection are occurring across the area. The first is an organizing line near the I-75 corridor in our eastern sections. This is being forced by the aforementioned mid-level wave and by diurnal heating. This activity will continue to head east and into WFO JKL`s area over the next hour or so. Further west, a well defined residual outflow boundary was located along our border with WFO IND. This boundary extends from northern Dubois county NE to Jefferson County. Convection is firing along this boundary due to strong moisture convergence and diurnal heating. This activity should head east-southeast over the next few hours. Finally additional convection is firing also over west KY. Based on the latest runs of the LMK WRF and 4km HRRR runs, this activity should also head east-southeast and may impact our far southwestern counties later this afternoon. Based on RUC proximity soundings, this afternoon`s convective activity is likely to remain in the pulse variety with damaging winds, torrential rains and intense CG lightning being the main threats. Latest deterministic and ensemble model runs seem to be showing some forecast convergence with the forecast for later this evening and overnight. First mid-level trough will scoot east this evening while a secondary and more potent mid-level trough dropping down into the Ohio Valley late tonight. As this wave drops south, surface cyclone near KSTL will shift northeast while associated surface cold drags behind. Strong mid-level height falls will result in widespread synoptic scale lift across the region late tonight. This combined with forcing along the front should result in a secondary line of convection developing to our northwest and slide southeast overnight. Despite this line moving through during an instability minimum, the upper level dynamics appear to be strong enough to support convection despite the meager instability. Current thinking is that a convective line will generate along the I-70 corridor and then drop southeast overnight. The line will likely be strong to possibly severe especially to our northwest. However, as the line heads southeast, it is possible that line may weaken a bit as it slides through KY. Convection should be pushing through southern Indiana in the 04-06Z time frame and then through KY in the 06-11Z time frame. Have gone ahead and bumped up PoPs for the overnight period. Lows will remain mild with temperatures falling into the lower-mid 60s in the northwest and mid-upper 60s elsewhere. For Friday, the main forecast change here is that a lot more cloud cover will be likely during the morning hours. Latest model time-height model cross sections show plenty of low-level moisture lingering behind the frontal boundary as it pushes through. Thus, mostly cloudy skies seem very likely in the morning followed by progressive clearing during the afternoon and into the evening hours. Highs tomorrow will be quite cool compared to what we`ve seen over the last few months. We should see readings in the upper 70s in the east with upper 70s to lower 80s in the central and west. Lows Friday night will be quite comfortable with lows in the mid-upper 50s. .Long Term (Saturday through Thursday)... Issued at 315 PM EDT Thu Aug 9 2012 ...Mostly Sunny, Dry, and Cool Weekend Ahead... A vertically stacked unseasonably far south and strong closed low will begin to slowly fill over Lake Huron Saturday. This system will slowly weaken and slowly lift north towards St. James Bay by late Sunday. In its wake, it will leave residual troughing across the western Great Lakes and the upper Midwest. By early Saturday, the occluded front related to this upper low will already have moved well east of the Commonwealth. Much drier and cooler air originating in Canada, will have overspread the state by dawn Saturday. Expect mostly clear skies and relatively cool temperatures for the upcoming weekend. Dewpoints will likely fall into the lower 50s by Saturday afternoon. Highs will struggle to exceed 80 on Saturday with highs on Sunday warming just a few degrees into the lower 80s. Overnight lows early Sunday will quite likely reach into the upper 50s, with perhaps our urban areas remaining near 60. A broad longwave trough will remain centered roughly over the Great Lakes during the early portion of next week. This will ensure no repeat of the excessively hot temperatures of early August anytime soon. Both the latest GFS and the ECMWF show a disturbance sliding southeast towards the base of this longwave trough Monday and Tuesday. This system will approach the Commonwealth by late Monday. At the surface, this system will likely aid in the formation of a weak surface trough that may serve as a focus for convection beginning late Monday, possibly continuing through the bulk of Tuesday. Will introduce a chance of storms for the later half of Monday, extending through Tuesday. Temperatures will warm a bit within the Monday through Thursday time period. However, even by Wednesday through Friday, temperatures will not exceed our seasonal mid-August averages with highs remaining in the upper 80s to around 90 && .Aviation (00Z TAF issuance)... Issued at 709 PM EDT Thu Aug 9 2012 Convection continues across the forecast area this evening. An east-west outflow boundary is roughly located along I-64 in southern Indiana and Kentucky. Two areas of convection are located along this boundary...the western cluster is centered over near KHNB while the eastern one is located northeast of KLEX. In general, convection should wind down temporarily over the next few hours as instability wanes. The terminals should generally see VFR conditions this evening. Secondary upper level wave and associated cold front are currently located to our northwest up north of I-70. Regional radars show an expanding area of convection across central IL and IN. This convection is progged to move east-southeast and will affect primarily the KSDF and KLEX terminals later tonight...most likely after 10/04Z. Convection reaching the KBWG area is much more uncertain as many of the 18Z numerical model runs weaken the line of convection as it heads through KY. For now have gone a little more optimistic at KBWG and plan on carrying only VCTS for the overnight period. It still looks like we`ll have plenty of low clouds in the morning with low end MVFR cigs during the morning hours. Progressive clearing looks to take place after 10/15Z. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...NONE. KY...NONE. $$ Update...........AMS Short Term.......MJ Long Term........JSD Aviation.........MJ
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
709 PM EDT THU AUG 09 2012 ...Updated Aviation Discussion... .Short Term (Tonight through Friday Night)... Issued at 331 PM EDT Thu Aug 9 2012 ...Active Period of Weather Expected This Afternoon and Tonight... Fairly active period of weather is shaping up for the Ohio Valley this afternoon and tonight. In the near term, mid-level shortwave combined with surface temperatures hitting convective temperatures has resulted in convection firing across the region. Several areas of convection are occurring across the area. The first is an organizing line near the I-75 corridor in our eastern sections. This is being forced by the aforementioned mid-level wave and by diurnal heating. This activity will continue to head east and into WFO JKL`s area over the next hour or so. Further west, a well defined residual outflow boundary was located along our border with WFO IND. This boundary extends from northern Dubois county NE to Jefferson County. Convection is firing along this boundary due to strong moisture convergence and diurnal heating. This activity should head east-southeast over the next few hours. Finally additional convection is firing also over west KY. Based on the latest runs of the LMK WRF and 4km HRRR runs, this activity should also head east-southeast and may impact our far southwestern counties later this afternoon. Based on RUC proximity soundings, this afternoon`s convective activity is likely to remain in the pulse variety with damaging winds, torrential rains and intense CG lightning being the main threats. Latest deterministic and ensemble model runs seem to be showing some forecast convergence with the forecast for later this evening and overnight. First mid-level trough will scoot east this evening while a secondary and more potent mid-level trough dropping down into the Ohio Valley late tonight. As this wave drops south, surface cyclone near KSTL will shift northeast while associated surface cold drags behind. Strong mid-level height falls will result in widespread synoptic scale lift across the region late tonight. This combined with forcing along the front should result in a secondary line of convection developing to our northwest and slide southeast overnight. Despite this line moving through during an instability minimum, the upper level dynamics appear to be strong enough to support convection despite the meager instability. Current thinking is that a convective line will generate along the I-70 corridor and then drop southeast overnight. The line will likely be strong to possibly severe especially to our northwest. However, as the line heads southeast, it is possible that line may weaken a bit as it slides through KY. Convection should be pushing through southern Indiana in the 04-06Z time frame and then through KY in the 06-11Z time frame. Have gone ahead and bumped up PoPs for the overnight period. Lows will remain mild with temperatures falling into the lower-mid 60s in the northwest and mid-upper 60s elsewhere. For Friday, the main forecast change here is that a lot more cloud cover will be likely during the morning hours. Latest model time-height model cross sections show plenty of low-level moisture lingering behind the frontal boundary as it pushes through. Thus, mostly cloudy skies seem very likely in the morning followed by progressive clearing during the afternoon and into the evening hours. Highs tomorrow will be quite cool compared to what we`ve seen over the last few months. We should see readings in the upper 70s in the east with upper 70s to lower 80s in the central and west. Lows Friday night will be quite comfortable with lows in the mid-upper 50s. .Long Term (Saturday through Thursday)... Issued at 315 AM EDT Thu Aug 9 2012 ...Mostly Sunny, Dry, and Cool Weekend Ahead... A vertically stacked unseasonably far south and strong closed low will begin to slowly fill over Lake Huron Saturday. This system will slowly weaken and slowly lift north towards St. James Bay by late Sunday. In its wake, it will leave residual troughing across the western Great Lakes and the upper Midwest. By early Saturday, the occluded front related to this upper low will already have moved well east of the Commonwealth. Much drier and cooler air originating in Canada, will have overspread the state by dawn Saturday. Expect mostly clear skies and relatively cool temperatures for the upcoming weekend. Dewpoints will likely fall into the lower 50s by Saturday afternoon. Highs will struggle to exceed 80 on Saturday with highs on Sunday warming just a few degrees into the lower 80s. Overnight lows early Sunday will quite likely reach into the upper 50s, with perhaps our urban areas remaining near 60. A broad longwave trough will remain centered roughly over the Great Lakes during the early portion of next week. This will ensure no repeat of the excessively hot temperatures of early August anytime soon. Both the latest GFS and the ECMWF show a disturbance sliding southeast towards the base of this longwave trough Monday and Tuesday. This system will approach the Commonwealth by late Monday. At the surface, this system will likely aid in the formation of a weak surface trough that may serve as a focus for convection beginning late Monday, possibly continuing through the bulk of Tuesday. Will introduce a chance of storms for the later half of Monday, extending through Tuesday. Temperatures will warm a bit within the Monday through Thursday time period. However, even by Wednesday through Friday, temperatures will not exceed our seasonal mid-August averages with highs remaining in the upper 80s to around 90 && .Aviation (00Z TAF issuance)... Issued at 709 PM EDT Thu Aug 9 2012 Convection continues across the forecast area this evening. An east-west outflow boundary is roughly located along I-64 in southern Indiana and Kentucky. Two areas of convection are located along this boundary...the western cluster is centered over near KHNB while the eastern one is located northeast of KLEX. In general, convection should wind down temporarily over the next few hours as instability wanes. The terminals should generally see VFR conditions this evening. Secondary upper level wave and associated cold front are currently located to our northwest up north of I-70. Regional radars show an expanding area of convection across central IL and IN. This convection is progged to move east-southeast and will affect primarily the KSDF and KLEX terminals later tonight...most likely after 10/04Z. Convection reaching the KBWG area is much more uncertain as many of the 18Z numerical model runs weaken the line of convection as it heads through KY. For now have gone a little more optimistic at KBWG and plan on carrying only VCTS for the overnight period. It still looks like we`ll have plenty of low clouds in the morning with low end MVFR cigs during the morning hours. Progressive clearing looks to take place after 10/15Z. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...NONE. KY...NONE. $$ Short Term.......MJ Long Term........JSD Aviation.........MJ
AREA FORECAST DISCUSSION
NWS CARIBOU ME
102 AM EDT WED AUG 8 2012 .SYNOPSIS... HIGH PRESSURE WILL MOVE EAST OF THE AREA TONIGHT. A WEAK FRONTAL BOUNDARY WILL APPROACH FROM THE NORTHWEST ON WEDNESDAY AND STALL OVER THE AREA THROUGH LATE WEEK. && .NEAR TERM /THROUGH TODAY/... 1 AM UPDATE...ADJUSTED SKY GRID TO ACCOUNT FOR LATEST SATELLITE TREND. 10 PM UPDATE...TWEAKED TEMPERATURES TO MATCH THE LATEST TRENDS. RADAR SHOWING SOME SHOWERS MOVE NE ACROSS QUEBEC. RUC HAS SOME OF THESE SHOWERS SKIRTING NORTHERN AND NWRN AREAS OVERNIGHT INTO EARLY MORNING. LATEST FCST HAS THIS HANDLED WELL. PREVIOUS DISCUSSION... TONIGHT WILL REMAIN MOSTLY CLEAR IN SOUTHERN AND SOUTHEAST AREAS. SOME CLOUDS WILL GRADUALLY INCREASE ACROSS THE NORTHWEST AS A WEAK COLD FRONT SLOWLY APPROACHES FROM QUEBEC. SOME SHOWERS MAY AFFECT FAR NORTHWESTERN AREAS LATE TONIGHT OR WEDNESDAY MORNING. AS THE FRONT NEARS WEDNESDAY AFTERNOON SOME THUNDERSTORMS WILL BE POSSIBLE. THE BEST CHANCES FOR THUNDERSTORMS WEDNESDAY AFTERNOON WILL BE OVER FAR NORTHWESTERN AREAS NEAR THE FRONTAL BOUNDARY WHERE SOME CONVERGENCE WILL OFFER SUPPORT FOR THUNDERSTORM ACTIVITY. BOTH THE NAM AND GFS ARE FORECASTING CAPES NEAR 300 J/KG. CAPES AROUND 300 CAN SUPPORT SOME CONVECTION BUT ARE LIKELY TOO WEAK TO SUPPORT ANYTHING SEVERE. TEMPS TONIGHT WILL RANGE FROM THE MID 50S EAST WHERE SKIES WILL BE MOSTLY CLEAR TO NEAR 60 NORTHWEST WHERE SOME CLOUD COVER WILL LIMIT COOLING. TEMPS ON WEDNESDAY WILL BE IN THE LOW 80S IN MOST AREAS. && .SHORT TERM /TONIGHT THROUGH 6 PM THURSDAY/... A WEAK AREA OF LOW PRESSURE AND AN ASSOCIATED COLD FRONT WILL MOVE ACROSS THE REGION WEDNESDAY NIGHT BRINGING SOME SHOWERS AND THUNDERSTORMS MAINLY TO THE NORTHERN HALF OF THE REGION. AS ABUNDANT LOW LEVEL MOISTURE IS DRAWN NORTH ON SOUTHERLY WINDS AHEAD OF THE FRONT THIS WILL RESULT IN FOG DEVELOPMENT OVER DOWNEAST AREAS. THE FRONT STALLS ACROSS THE REGION ON THURSDAY RESULTING IN CONSIDERABLE CLOUDINESS WITH ADDITIONAL SHOWERS AND THUNDERSTORMS. THE NAM DEPICTS CAPE VALUES EXCEEDING 1000 J/KG BY THE AFTERNOON WITH 0-6 KM SHEAR VALUES EXCEEDING 40 KNOTS. HOWEVER CLOUD COVER WILL ACT TO LIMIT THE POTENTIAL FOR SEVERE STORMS AS IT LIMITS HEATING. HAVE GONE WITH UPPER 70S NORTH AND LOW 80S SOUTH. ANY CONVECTION WILL WIND DOWN THURSDAY EVENING. HAVE MAINTAINED SHOWERS THROUGH THE NIGHT WITH THE FRONT STALLING DOWN EAST. LOWS WILL BE IN THE LOW TO MID 60S IN THE RATHER HUMID AIR MASS. MODELS BEGIN TO DIVERGE HEADING INTO FRIDAY. LOW PRESSURE LOOKS TO DEVELOP FRIDAY IN THE OHIO VALLEY WITH A SHIELD OF RAIN EXTENDING NORTH AND EAST FROM THIS SYSTEM ALONG THE FRONT. THE NAM AND THE ECMWF ARE FAIRLY AGGRESSIVE BRINGING STEADIER AND HEAVIER PRECIPITATION INTO THE REGION DURING THE DAY COMPARED TO THE GFS AND ESPECIALLY THE GEM GLOBAL. AT THIS POINT OPTED TO KEEP IN CHANCE POPS OVER MOST OF THE CWA WITH A SMALL AREA OF LIKELY POPS NUDGING INTO AREAS JUST WEST OF BANGOR BY LATE DAY. && .LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/... LOW PRESSURE WILL INTENSIFY ACROSS THE MID ATLANTIC REGION FRIDAY NIGHT WITH HIGH PRESSURE LOCATED NORTH OF THE REGION. THE LOW THEN SLOWLY LIFTS NORTH SATURDAY...WHILE HIGH PRESSURE MOVES NORTHEAST. UNCERTAINTY STILL EXISTS REGARDING HOW QUICKLY RAIN IS ABLE TO EXPAND ACROSS THE FORECAST AREA FRIDAY NIGHT THROUGH SATURDAY. HIGH PRESSURE TO THE NORTHEAST SHOULD HELP SUPPLY LOW LEVEL DRY AIR WHICH COULD SLOW THE EXPANSION OF RAIN ACROSS THE REGION. EXPECT THE BEST CHANCES OF RAIN WILL REMAIN ACROSS SOUTHWEST PORTIONS OF THE FORECAST AREA FRIDAY NIGHT THROUGH EARLY SATURDAY. THE RAIN SHOULD THEN EXPAND ACROSS THE REGION THROUGH THE REMAINDER OF SATURDAY. THE LOW WILL LIFT NORTH SATURDAY NIGHT THROUGH SUNDAY...DRAWING AN OCCLUDED FRONT ACROSS THE FORECAST AREA. RAIN IS EXPECTED ACROSS THE ENTIRE REGION SATURDAY NIGHT THROUGH EARLY SUNDAY IN ADVANCE OF THE OCCLUSION...WITH PRECIPITATION THEN TAPERING TO SHOWERS IN THE WAKE OF THE OCCLUSION LATER SUNDAY. THE LOW WILL LIFT NORTH OF THE REGION MONDAY...WITH A SLIGHT CHANCE OF SHOWERS LINGERING ACROSS NORTHERN AREAS. A COLD FRONT WILL APPROACH LATER TUESDAY BRINGING A CHANCE OF SHOWERS AND THUNDERSTORMS TO MOSTLY NORTHERN AREAS DURING THE AFTERNOON. TEMPERATURES SHOULD BE AT SLIGHTLY BELOW NORMAL LEVELS SATURDAY/SUNDAY...WITH NEAR NORMAL LEVEL TEMPERATURES EXPECTED MONDAY/TUESDAY. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... NEAR TERM: SOME PATCHY FOG MAY AFFECT DOWNEAST AREAS LATE TONIGHT. OTHERWISE...VFR CONDITIONS ARE EXPECTED ACROSS THE AREA THROUGH WEDNESDAY. SHORT TERM: IFR LIKELY TO DEVELOP WEDNESDAY NIGHT SOUTH OF HUL AND MLT WITH STRATUS AND FOG. THIS WILL CONTINUE INTO EARLY THURSDAY MORNING. VFR FOR LATER THURSDAY MORNING INTO THE EVENING OUTSIDE OF THUNDERSTORMS. FOG AND STRATUS REAPPEARS THURSDAY NIGHT FOR ALL TERMINALS AND MAY BE VERY SLOW TO LIFT FRIDAY MORNING...ESPECIALLY DOWNEAST. LOW PRESSURE ARRIVES BY LATE DAY TO PROVIDE PREDOMINANT IFR FOR ALL SITES DUE TO LOW CLOUDS AND RAIN. CONDITIONS FRIDAY NIGHT THROUGH SATURDAY WILL BE DEPENDENT ON HOW QUICKLY RAIN IS ABLE TO EXPAND ACROSS THE REGION. HOWEVER...MVFR/IFR CONDITIONS ARE POSSIBLE FRIDAY NIGHT INTO SATURDAY WITH A MORE RAPID EXPANSION OF THE RAIN. MVFR/IFR CONDITIONS ARE THEN EXPECTED SATURDAY NIGHT INTO SUNDAY. && .MARINE... NEAR TERM: WINDS AND SEAS ARE EXPECTED TO REMAIN BELOW SCA TONIGHT AND WEDNESDAY. SHORT TERM: FOG IS EXPECTED WEDNESDAY NIGHT AND WILL REMAIN A FACTOR IN THE FORECAST THROUGH FRIDAY. CONDITIONS ARE EXPECTED TO BE BELOW SMALL CRAFT ADVISORY LEVELS WEDNESDAY NIGHT THROUGH FRIDAY. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...NONE. MARINE...NONE. && $$ NEAR TERM...HEWITT/RUNYAN
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
250 PM EDT WED AUG 8 2012 .SYNOPSIS... INCREASING HUMIDITY, PLUS A CANADIAN COLD FRONT MOVING SOUTHWARD TOWARD LAKE ERIE, MAY SPARK SCATTERED THUNDERSTORMS THIS AFTERNOON AND EVENING AND AGAIN LATE THURSDAY ACROSS THE UPPER OHIO VALLEY. LOW PRESSURE, COMING EAST FROM MINNESOTA, WILL JOIN THE COLD FRONT AND BRING MORE NUMEROUS SHOWERS AND THUNDERSTORMS FRIDAY. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... RECENT RADAR DATA NOW SHOWS A BAND OF SCATTERED THUNDERSTORMS DEVELOPING ALONG THE LAKE ERIE BREEZE FRONT. WITH SURFACE DEW POINTS HAVING INCREASED INTO THE 60 TO 65 RANGE ACROSS NORTHERN OHIO AND THE PENNSYLVANIA I-80 CORRIDOR, EXPECT THESE STORMS TO EXPAND IN COVERAGE AND MOVE SOUTHEASTWARD INTO EAST CENTRAL OHIO AND WEST CENTRAL PENNSYLVANIA BEFORE 6 PM, A SCENARIO PREDICTED BY RECENT HRRR MODEL OUTPUT. STORM INTENSITY WILL NEED MONITORED AS SPC CONTINUES TO PROJECT SOME SEVERE POTENTIAL. SREF MODEL OUTPUT SUPPORTS THIS IDEA AS IT SHOWS INSTABILITY CAN PEAK ABOVE 1500 J/KG AND VERTICAL WIND SHEAR MAY REACH 30 KTS. FORECASTED HIGH TEMPERATURES IN THE 85 TO 90 RANGE, BUT SUCH HIGHS COULD BE REDUCED IF THUNDERSTORMS PASS THROUGH AN AREA PRIOR TO 5 PM. AFTER DARK, NOCTURNAL COOLING WILL DISSIPATE CONVECTIVE INSTABILITY. PATCHY RIVER VALLEY FOG CAN AGAIN DEVELOP AS IT HAS ON PREVIOUS NIGHTS, AN IDEA SUPPORTED BY RECENT GFS LAMP OUTPUT. FORECASTED LOW TEMPERATURES USING A BLEND OF RECENT NAM AND GFS MOS. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/... RECENT SREF MODEL OUTPUT, WITH DETAILS FROM THE NAM, SHOW THE COLD FRONT WILL BECOME STALLED, IN A WEST TO EAST ORIENTATION, ACROSS THE UPPER OHIO VALLEY THURSDAY. EXPECT BANDS OF SCATTERED THUNDERSTORMS TO DEVELOP DAYTIME THURSDAY, DUE TO LOW LEVEL CONVERGENCE IN ADVANCE OF A LOW PRESSURE CENTER COMING EAST FROM MINNESOTA AND IOWA. SPC HAS MAINTAINED A SLIGHT RISK OF SEVERE THUNDERSTORMS THURSDAY AFTERNOON INTO EARLY FRIDAY, WHICH IS SUPPORTED BY SREF MODEL OUTPUT PROJECTIONS OF INSTABILITY, CAPE 2000+ J/KG, AND VERTICAL WIND SHEAR, EFFECTIVE BULK SHEAR 25 KTS. EXPECT SHOWERS AND THUNDERSTORMS TO BE LIKELY FRIDAY DAYTIME AND EARLY EVENING WITH THE NORTHEAST PASSAGE OF THE DEEPENING LOW PRESSURE CENTER. CONCUR WITH HPC THAT WIDESPREAD RAIN AMOUNTS CAN EXCEED 0.50 INCHES, IF NOT 1 INCH. AS THE LOW PRESSURE CENTER MOVES NORTHWARD PAST LAKE ERIE LATE FRIDAY NIGHT AND DAYTIME SATURDAY, EXPECT WRAP-AROUND SHOWERS TO DECREASE IN COVERAGE. DUE TO THE PROSPECTS FOR SHOWERS AND ACCOMPANYING CLOUDINESS, CONCURRED WITH GFS AND NAM MOS IN FORECASTING HIGHS THURSDAY NOT AS WARM AS WEDNESDAY AND THEN COOLER THAN NORMAL FRIDAY. CLOUDS AT NIGHT AND HUMID CONDITIONS WILL KEEP LOWS WARMER THAN NORMAL THURSDAY NIGHT. LOWS FRIDAY NIGHT AND HIGHS SATURDAY CAN BE SLIGHTLY COOLER THAN NORMAL DUE TO COOLER AIR ALOFT. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... WRAPAROUND PRECIPITATION SHOULD BE SHIFTING TO THE NORTHEAST BY SATURDAY NIGHT...AND HAVE REMOVED PRECIPITATION AFTER MIDNIGHT. 00Z GFS SEEMS TO BE AN OUTLIER IN SHOWING DIURNAL PRECIPITATION FOR NEXT WEEK. OTHER MODEL CONSENSUS KEEPS HIGH PRESSURE THROUGH THE PERIOD...AND HAVE STUCK WITH THIS DRY DEPICTION. SUNDAY AND MONDAY SHOULD CONTINUE THE TREND OF SLIGHTLY BELOW NORMAL TEMPERATURES, WITH A SLIGHT RISE IN HIGHS ON TUESDAY AND WEDNESDAY. && .AVIATION /19Z WEDNESDAY THROUGH MONDAY/... WEAK FRONT WILL APPROACH THE REGION AND BECOME STATIONARY OVERNIGHT. THE FRONT OR A LAKE BREEZE BOUNDARY OFF LAKE ERIE COULD SPAWN SOME SCATTERED SHOWERS/THUNDERSTORMS DURING THE AFTERNOON AND EARLY EVENING HOURS. CONFIDENCE IS STILL NOT HIGH ENOUGH IN ANY SINGLE LOCATION TO BE SPECIFIC ABOUT TAF MENTION. OVERNIGHT...ALL GUIDANCE SUGGESTS A DROP TO AT LEAST MVFR VISIBILITY...IF NOT LOWER. ALTHOUGH WINDS SHOULD DROP TO 2-3 KTS OVERNIGHT...THINK THAT THE POSSIBILITY FOR FOG WILL BE DEPENDENT ON WHERE SHOWERS OCCUR DURING THE AFTERNOON. FOR NOW...WILL ADD MVFR VISIBILITIES AND ALLOW LATER TAF ISSUANCES TO DECIDE IF IFR VISIBILITIES ARE REQUIRED IN FORECAST. MID LEVEL CLOUDS WILL MOVE IN ON THURSDAY...WITH SCATTERED SHOWERS/STORMS EXPECTED BY THE AFTERNOON AGAIN. .OUTLOOK...THURSDAY NIGHT THROUGH MONDAY... RESTRICTIONS CAN BE EXPECTED IN WIDESPREAD SHOWERS AND THUNDERSTORMS FRIDAY AND FRIDAY NIGHT...WITH MORE ISOLATED COVERAGE EXPECTED SATURDAY AND SATURDAY NIGHT. SUNDAY SHOULD SEE A RETURN TO VFR CONDITIONS. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
246 PM EDT WED AUG 8 2012 .SYNOPSIS... INCREASING HUMIDITY, PLUS A CANADIAN COLD FRONT MOVING SOUTHWARD TOWARD LAKE ERIE, MAY SPARK SCATTERED THUNDERSTORMS THIS AFTERNOON AND EVENING AND AGAIN LATE THURSDAY ACROSS THE UPPER OHIO VALLEY. LOW PRESSURE, COMING EAST FROM MINNESOTA, WILL JOIN THE COLD FRONT AND BRING MORE NUMEROUS SHOWERS AND THUNDERSTORMS FRIDAY. && .NEAR TERM /THROUGH TONIGHT/... RECENT RADAR DATA NOW SHOWS A BAND OF SCATTERED THUNDERSTORMS DEVELOPING ALONG THE LAKE ERIE BREEZE FRONT. WITH SURFACE DEW POINTS HAVING INCREASED INTO THE 60 TO 65 RANGE ACROSS NORTHERN OHIO AND THE PENNSYLVANIA I-80 CORRIDOR, EXPECT THESE STORMS TO EXPAND IN COVERAGE AND MOVE SOUTHEASTWARD INTO EAST CENTRAL OHIO AND WEST CENTRAL PENNSYLVANIA BEFORE 6 PM, A SCENARIO PREDICTED BY RECENT HRRR MODEL OUTPUT. STORM INTENSITY WILL NEED MONITORED AS SPC CONTINUES TO PROJECT SOME SEVERE POTENTIAL. SREF MODEL OUTPUT SUPPORTS THIS IDEA AS IT SHOWS INSTABILITY CAN PEAK ABOVE 1500 J/KG AND VERTICAL WIND SHEAR MAY REACH 30 KTS. FORECASTED HIGH TEMPERATURES IN THE 85 TO 90 RANGE, BUT SUCH HIGHS COULD BE REDUCED IF THUNDERSTORMS PASS THROUGH AN AREA PRIOR TO 5 PM. AFTER DARK, NOCTURNAL COOLING WILL DISSIPATE CONVECTIVE INSTABILITY. PATCHY RIVER VALLEY FOG CAN AGAIN DEVELOP AS IT HAS ON PREVIOUS NIGHTS, AN IDEA SUPPORTED BY RECENT GFS LAMP OUTPUT. FORECASTED LOW TEMPERATURES USING A BLEND OF RECENT NAM AND GFS MOS. && .SHORT TERM /THURSDAY THROUGH SATURDAY/... RECENT SREF MODEL OUTPUT, WITH DETAILS FROM THE NAM, SHOW THE COLD FRONT WILL BECOME STALLED, IN A WEST TO EAST ORIENTATION, ACROSS THE UPPER OHIO VALLEY THURSDAY. EXPECT BANDS OF SCATTERED THUNDERSTORMS TO DEVELOP DAYTIME THURSDAY, DUE TO LOW LEVEL CONVERGENCE IN ADVANCE OF A LOW PRESSURE CENTER COMING EAST FROM MINNESOTA AND IOWA. SPC HAS MAINTAINED A SLIGHT RISK OF SEVERE THUNDERSTORMS THURSDAY AFTERNOON INTO EARLY FRIDAY, WHICH IS SUPPORTED BY SREF MODEL OUTPUT PROJECTIONS OF INSTABILITY, CAPE 2000+ J/KG, AND VERTICAL WIND SHEAR, EFFECTIVE BULK SHEAR 25 KTS. EXPECT SHOWERS AND THUNDERSTORMS TO BE LIKELY FRIDAY DAYTIME AND EARLY EVENING WITH THE NORTHEAST PASSAGE OF THE DEEPENING LOW PRESSURE CENTER. CONCUR WITH HPC THAT WIDESPREAD RAIN AMOUNTS CAN EXCEED 0.50 INCHES, IF NOT 1 INCH. AS THE LOW PRESSURE CENTER MOVES NORTHWARD PAST LAKE ERIE LATE FRIDAY NIGHT AND DAYTIME SATURDAY, EXPECT WRAP-AROUND SHOWERS TO DECREASE IN COVERAGE. DUE TO THE PROSPECTS FOR SHOWERS AND ACCOMPANYING CLOUDINESS, CONCURRED WITH GFS AND NAM MOS IN FORECASTING HIGHS THURSDAY NOT AS WARM AS WEDNESDAY AND THEN COOLER THAN NORMAL FRIDAY. CLOUDS AT NIGHT AND HUMID CONDITIONS WILL KEEP LOWS WARMER THAN NORMAL THURSDAY NIGHT. LOWS FRIDAY NIGHT AND HIGHS SATURDAY CAN BE SLIGHTLY COOLER THAN NORMAL DUE TO COOLER AIR ALOFT. && .LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/... WRAPAROUND PRECIPITATION SHOULD BE SHIFTING TO THE NORTHEAST BY SATURDAY NIGHT...AND HAVE REMOVED PRECIPITATION AFTER MIDNIGHT. 00Z GFS SEEMS TO BE AN OUTLIER IN SHOWING DIURNAL PRECIPITATION FOR NEXT WEEK. OTHER MODEL CONSENSUS KEEPS HIGH PRESSURE THROUGH THE PERIOD...AND HAVE STUCK WITH THIS DRY DEPICTION. SUNDAY AND MONDAY SHOULD CONTINUE THE TREND OF SLIGHTLY BELOW NORMAL TEMPERATURES, WITH A SLIGHT RISE IN HIGHS ON TUESDAY. && .AVIATION /19Z WEDNESDAY THROUGH MONDAY/... WEAK FRONT WILL APPROACH THE REGION AND BECOME STATIONARY OVERNIGHT. THE FRONT OR A LAKE BREEZE BOUNDARY OFF LAKE ERIE COULD SPAWN SOME SCATTERED SHOWERS/THUNDERSTORMS DURING THE AFTERNOON AND EARLY EVENING HOURS. CONFIDENCE IS STILL NOT HIGH ENOUGH IN ANY SINGLE LOCATION TO BE SPECIFIC ABOUT TAF MENTION. OVERNIGHT...ALL GUIDANCE SUGGESTS A DROP TO AT LEAST MVFR VISIBILITY...IF NOT LOWER. ALTHOUGH WINDS SHOULD DROP TO 2-3 KTS OVERNIGHT...THINK THAT THE POSSIBILITY FOR FOG WILL BE DEPENDENT ON WHERE SHOWERS OCCUR DURING THE AFTERNOON. FOR NOW...WILL ADD MVFR VISIBILITIES AND ALLOW LATER TAF ISSUANCES TO DECIDE IF IFR VISIBILITIES ARE REQUIRED IN FORECAST. MID LEVEL CLOUDS WILL MOVE IN ON THURSDAY...WITH SCATTERED SHOWERS/STORMS EXPECTED BY THE AFTERNOON AGAIN. .OUTLOOK...THURSDAY NIGHT THROUGH SUNDAY... RESTRICTIONS CAN BE EXPECTED IN WIDESPREAD SHOWERS AND THUNDERSTORMS FRIDAY AND FRIDAY NIGHT...WITH MORE ISOLATED COVERAGE EXPECTED SATURDAY AND SATURDAY NIGHT. SUNDAY SHOULD SEE A RETURN TO VFR CONDITIONS. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1132 AM EDT WED AUG 8 2012 .SYNOPSIS...INCREASING HUMIDITY, PLUS A CANADIAN COLD FRONT MOVING SOUTHWARD TOWARD LAKE ERIE, MAY SPARK SCATTERED THUNDERSTORMS THIS AFTERNOON AND EVENING AND AGAIN LATE THURSDAY ACROSS THE UPPER OHIO VALLEY. LOW PRESSURE, COMING EAST FROM MINNESOTA, WILL JOIN THE COLD FRONT AND BRING MORE NUMEROUS SHOWERS AND THUNDERSTORMS FRIDAY. && .NEAR TERM /THROUGH TONIGHT/... ALTHOUGH SATELLITE DATA AND NAM MODEL PROFILES SHOW SKIES WILL STAY MAINLY SUNNY INTO EARLY AFTERNOON. NAM MODEL PROFILES COMBINED WITH HRRR AND WRF-NMM MODEL OUTPUT, COUPLED WITH RECENT RADAR DATA, SUGGEST ONCE SURFACE TEMPERATURES REACH THE MID 80S, CUMULONIMBUS AND THUNDERSTORMS CAN DEVELOP. HRRR MODEL OUTPUT SPECIFICALLY SHOWS A BAND OF THESE SCATTERED THUNDERSTORMS CAN MOVE SOUTHEASTWARD ACROSS MUCH OF THE UPPER OHIO VALLEY THROUGH EARLY EVENING. STORM INTENSITY WILL NEED MONITORED AS SPC HAS INDICATED SOME SEVERE POTENTIAL. SREF MODEL OUTPUT SUPPORTS THIS IDEA AS IT SHOWS INSTABILITY CAN PEAK ABOVE 1500 J/KG AND VERTICAL WIND SHEAR MAY REACH 30 KTS. FORECASTED HIGH TEMPERATURES IN THE 85 TO 90 RANGE, BUT THESE COULD BE REDUCED IF THUNDERSTORMS PASS THROUGH AN AREA PRIOR TO 5 PM. AFTER DARK, NOCTURNAL COOLING WILL DISSIPATE CONVECTIVE INSTABILITY. PATCHY RIVER VALLEY FOG CAN AGAIN DEVELOP AS IT HAS ON PREVIOUS NIGHTS, AN IDEA SUPPORTED BY RECENT GFS LAMP OUTPUT. FORECASTED LOW TEMPERATURES USING A BLEND OF RECENT NAM AND GFS MOS. && .SHORT TERM /THURSDAY THROUGH FRIDAY/... COLD FRONT WILL BECOME STALLED IN A WEST TO EAST ORIENTATION ACROSS THE UPPER OHIO VALLEY THURSDAY AS AN EASTBOUND UPPER LEVEL SHORTWAVE TROUGH WILL UP THE RISK FOR SHOWERS/STORMS. THIS NEXT UPPER LEVEL SYSTEM WILL HAVE MORE MOISTURE TO TAP INTO AND HAVE A BIT MORE OF A PUNCH, SO THERE SHOULD BE AT LEAST SCATTERED THUNDERSTORMS THURSDAY AND THURSDAY NIGHT. SPC HAS MAINTAINED A SLIGHT RISK OF SEVERE THUNDERSTORMS THURSDAY AFTERNOON INTO EARLY FRIDAY, WHICH SREF MODEL OUTPUT PROJECTIONS OF INSTABILITY AND VERTICAL WIND SHEAR SUPPORT. A LARGER SYSTEM, BOTH IN THE UPPER LEVELS AND AT THE SFC WILL MOVE THROUGH THE UPPER OHIO VALLEY FRIDAY, MAKING SHOWERS AND THUNDERSTORMS LIKELY. DUE TO THE PROSPECTS FOR SHOWERS AND ACCOMPANYING CLOUDINESS, CONCURRED WITH GFS AND NAM MOS IN FORECASTING HIGHS THURSDAY NOT AS WARM AS WEDNESDAY AND THEN COOLER THAN NORMAL FRIDAY. CLOUDS AT NIGHT AND HUMID CONDITIONS WILL KEEP LOWS WARMER THAN NORMAL. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... BLEND OF RECENT GFS AND ECMWF MODEL OUTPUT SHOWS THE WELL- DEVELOPED LOW PRESSURE SYSTEM MOVING NORTHWARD PAST THE EASTERN GREAT LAKES THIS WEEKEND. THIS CAN MAINTAIN WRAP-AROUND SHOWERS ACROSS THE UPPER OHIO VALLEY AT LEAST THROUGH SATURDAY WITH THE TREND FOR DRIER CONDITIONS BY SUNDAY. HIGH PRESSURE COMING EAST FROM THE PLAINS SHOULD PROVIDE A DRY PERIOD MONDAY AND PERHAPS TUESDAY. THE EFFECTS OF COOLER TEMPERATURE ALOFT AND INSTABILITY CLOUDS AND SHOWERS WILL PROVIDE COOLER THAN NORMAL TEMPERATURES THIS WEEKEND. LESS CLOUDS MONDAY AND TUESDAY SHOULD ALLOW DAYTIME TEMPERATURES REBOUND TO VALUES NEAR OR SLIGHTLY WARMER THAN NORMAL, AS INDICATED BY RECENT GFS AND ECMWF MOS. && .AVIATION /15Z WEDNESDAY THROUGH SUNDAY/... VFR WILL BE PREVALENT INTO TONIGHT. HOWEVER A WEAK SYSTEM MOVING EASTWARD THROUGH THE AREA THIS AFTERNOON MAY SPAWN A BAND OF SCATTERED THUNDERSTORM WITH POTENTIAL RESTRICTIONS AND WIND GUSTS OVER 25 MPH. HOWEVER CONFIDENCE REGARDING COVERAGE AND TIMING IS STILL TOO LOW TO INCLUDE MENTION IN ANY TAF. .OUTLOOK...THURSDAY THROUGH SATURDAY... RESTRICTIONS ARE POSSIBLE IN SHOWERS AND THUNDERSTORMS, AND PATCHY EARLY MORNING FOG, INTO THE WEEKEND. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS BILLINGS MT
931 AM MDT WED AUG 8 2012 .SHORT TERM...VALID FOR TDY AND THU... UPDATE TO ZFP AND WRKAFP. A SHORTWAVE WAS SEEN OVER S ID THIS MORNING ON SATELLITE IMAGERY. RADAR SHOWED A BAND OF SHOWERS WITH THE WAVE AS WELL. NEW WRF AND RAP BROUGHT LIFT FROM THE WAVE INTO THE WESTERN MOUNTAINS BY 00Z TONIGHT ALONG WITH SOME PRECIPITATION. KLVM SOUNDING HAD .74 INCHES OF PRECIPITABLE WATER SO SOME MOISTURE WILL BE POSSIBLE WITH THUNDERSTORMS. HAVE ADDED SLIGHT CHANCE POPS TO THE WESTERN MOUNTAINS AND KLVM AREA THIS AFTERNOON. LOW-LEVEL FLOW WILL TURN EASTERLY E OF KBIL THIS AFTERNOON AS SURFACE HIGH OVER S SASKATCHEWAN SLIDES INTO THE DAKOTAS. THIS FLOW WILL CREATE AN INVERSION OVER THE EASTERN ZONES WHICH WILL SLOW TEMPERATURE RISES. THUS HAVE LOWERED MAX TEMPERATURES OVER KMLS AND KBHK AREAS. NO CHANGES TO REMAINDER OF FORECAST. ARTHUR .LONG TERM...VALID FOR FRI...SAT...SUN...MON...TUE... MADE A FEW CHANGES TO THE EXTENDED FORECAST AS DETAILS BECOME MORE VISIBLE AND CONSISTENT. ALTHOUGH LOCATED AT THE APEX OF BROAD UPPER LEVEL RIDGE THROUGH MUCH OF THE PERIOD...FLATTENED FLOW WILL ALLOW FOR THE POTENTIAL FOR A FAIRLY ACTIVE PERIOD WITH REGARD TO PRECIP. THE EXTENDED PERIOD BEGINS FRIDAY AS A A STRONG TROF CRASHES THROUGH THE UPPER LEVEL RIDGE. THIS BRINGS OUR BEST CHANCE OF PRECIPITATION ACROSS THE REGION...AS WELL AS RESULTS IN FLATTENING THE RIDGE FOR THE REMAINDER OF THE PERIOD. THE ONLY NEGATIVE IS THAT IT APPEARS TO BE VERY QUICK MOVING. SPLIT THE 00-12Z SATURDAY GRID TO CLEAR OUT WESTERN ZONES MORE QUICKLY BETWEEN FROM 06-12Z. ALSO TAPERED POPS BACK TO THE EAST FURTHER FOR THE 12Z-00Z SATURDAY GRID AS A RESULT OF QUICKER PACE OF THE SYSTEM. PATTERN REMAINS SOMEWHAT ZONAL THROUGH THE BEGINNING OF NEXT WEEK...WITH SEVERAL WAVES THROUGH THE FLOW. THESE WILL BRING SLIGHT CHANCES FOR PRECIP...BUT NOTHING TERRIBLY ORGANIZED TAKES SHAPE UNTIL LATE TUESDAY INTO WEDNESDAY. MODELS ARE STILL DIFFERING SIGNIFICANTLY ON SPECIFICS OF APPROACHING TROF...BUT FAVOR MAJOR COOL OFF AND A MORE PROLONGED PERIOD OF PRECIP TO END THE EXTENDED PERIOD. HAVE INTRODUCED HIGHS IN THE UPPER 80S AND ABOVE CLIMO TYPE SLIGHT POPS. MODELS SEEM TO SUPPORT MUCH COOLER TEMPS...AND HIGH POPS POTENTIAL...BUT IS STILL FAR IN THE FUTURE...AND SYSTEM STILL TAKING SHAPE. ABOVE NORMAL TEMPERATURES WILL CONTINUE THROUGH THE EXTENDED PERIOD...BUT LOOK LIKE THEY SHOULD BE MODERATED SOMEWHAT...ONLY IN LOW 90S FOR MOST PART...DUE TO FLAT FLOW AND MULTIPLE SHORTWAVES THROUGH THE REGION BRINING CLOUD COVER AND PRECIP. AAG && .AVIATION... MAINLY VFR CONDITIONS ARE EXPECTED ACROSS THE AREA TODAY. A FEW SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP ACROSS WESTERN ZONES...NEAR KLVM...THIS AFTERNOON. FLIGHT CONDITIONS COULD BE LOCALLY LOWERED TO MVFR IN AND AROUND THESE STORMS. A FEW OF THESE STORMS COULD PRODUCE SOME ERRATIC GUSTY WINDS AS WELL AS SOME LOCALIZED MOUNTAIN OBSCURATIONS. CHURCH && .PRELIMINARY POINT TEMP/POPS... TDY THU FRI SAT SUN MON TUE ------------------------------------------------------- BIL 098 064/094 061/092 061/091 060/094 060/093 059/091 0/U 12/T 23/T 41/B 11/B 21/B 12/T LVM 095 056/090 053/088 053/088 052/090 051/088 051/087 2/T 33/T 34/T 41/B 22/T 22/T 22/T HDN 100 062/097 062/095 061/094 061/097 060/096 059/094 0/U 12/T 23/T 41/U 22/T 22/T 12/T MLS 094 067/096 064/094 064/092 062/094 063/096 062/092 0/U 12/T 22/T 41/B 22/T 22/T 22/T 4BQ 096 063/096 063/093 062/092 061/094 061/094 060/093 0/U 11/B 22/T 42/T 22/T 22/T 22/T BHK 091 062/091 061/090 061/088 060/089 060/090 061/089 1/U 11/B 22/T 52/T 22/T 22/T 22/T SHR 095 060/093 058/091 058/089 056/092 057/094 056/090 0/U 01/B 23/T 41/B 22/T 22/T 11/B && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...NONE. WY...NONE. && $$ WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
604 PM CDT THU AUG 9 2012 .AVIATION...00Z TAFS FOR KOMA...KLNK AND KOFK. COULD BE SCATTERED CUMULUS CLOUDS AND GUSTS FROM THE NORTH UP TO ABOUT 18KTS THROUGH 01Z...THEN VFR CONDITIONS AFTER THAT WITH CLOUDS DISSIPATING. COULD SEE SOME MVFR FOG OVERNIGHT...ESPECIALLY AT KOFK AND KOMA FROM ABOUT 10-14Z. NORTHEAST WINDS AROUND 8KTS AFTER THAT THROUGH THE REMAINDER OF FRIDAY WITH CUMULUS DEVELOPING AGAIN AROUND 5000 FEET DEWALD && .PREV DISCUSSION... /ISSUED 305 PM CDT THU AUG 9 2012/ DISCUSSION... TEMPERATURES WILL PROVIDE THE PRIMARY FORECAST CHALLENGES THROUGH FRIDAY NIGHT...THEN ATTENTION SHIFTS MORE TOWARD PRECIPITATION CHANCES OVER THE WEEKEND. MAIN FEATURES FROM THE 12Z UPPER AIR CHARTS THIS MORNING SHOWED THE FOLLOWING. AT 300 MB...JETSTREAM CURVED NORTHEAST ACROSS THE PACIFIC NORTHWEST INTO THE NORTHERN PLAINS...THEN TURNED SOUTHEAST INTO THE OHIO VALLEY. A JET MAX OF AROUND 100 KNOTS WAS NOTED OVER MINNESOTA. AT 500 MB...A RATHER IMPRESSIVE CLOSED LOW WAS OVER NORTHEAST MINNESOTA WITH 12 HOUR HEIGHT FALLS OF 70 METERS NOTED AT KINL. THE CENTER OF A MID LEVEL RIDGE WAS OVER THE FOUR CORNERS REGION. COOLER AIR WAS PUSHING DOWN FROM MINNESOTA AND THE EASTERN DAKOTAS AT 700 MB AND 850 MB. SURFACE ANALYSIS EARLY THIS AFTERNOON INDICATED A RIDGE OF COOL HIGH PRESSURE EXTENDING FROM ONTARIO AND MANITOBA DOWN INTO THE NORTHERN AND WESTERN PLAINS. WINDS WERE MAINLY FROM THE NORTH OVER THE LOCAL AREA. THAT SURFACE RIDGE WILL BUILD EASTWARD ACROSS THE FORECAST AREA TONIGHT THROUGH FRIDAY NIGHT...WITH SEASONABLE TEMPERATURES AND DRY CONDITIONS. EXPECT SOME PATCHY FOG TONIGHT AS WINDS DECREASE... ESPECIALLY IN PARTS OF OUR CENTRAL AND EASTERN ZONES WHERE SPOTTY RAIN FELL YESTERDAY AND TUESDAY. EXPECT THAT TO BURN OFF QUICKLY FRIDAY...IF IT DEVELOPS...WITH SCATTERED CUMULUS MOST AREAS BY THE AFTERNOON. HIGHS FRIDAY WILL BE IN THE 80S...CLOSE TO NAM MOS. RETURN FLOW STRENGTHENS LATE FRIDAY NIGHT INTO SATURDAY AND MODELS ARE IN GENERAL AGREEMENT WITH LARGE SCALE PATTERN. THEY SHOW SOME 850-700 MB THETA E ADVECTION SPREADING FROM WEST TO EAST ON SATURDAY. LARGE SCALE FORCING SEEMS WEAK AT BEST...SO KEPT POPS ONLY AT 20 PERCENT AND TRIED TO CONFINE THOSE TO NORTHEAST NEBRASKA SATURDAY. A MODEST SHORTWAVE TROUGH DOES MOVE ACROSS THE PLAINS FOR SATURDAY NIGHT/EARLY SUNDAY...AND THIS IS PROBABLY OUR BEST CHANCE FOR THUNDERSTORMS. THE 12Z GFS SEEMED WAY TOO GENEROUS WITH QPF AND ITS OUTPUT WAS GENERALLY NOT USED. FAVORED A BLEND OF THE NAM AND ECMWF FOR NOW...BUT SHOULD BE ABLE TO ADJUST THINGS MORE AS WE GET CLOSER WITH 4 KM NAM AND HRRR MODELS. LINGERED SOME LOW POPS INTO SUNDAY BASED ON CURRENT MODEL TIMING OF FORCING. OTHERWISE...LOOK FOR DEAMPLIFICATION OF THE 500 MB PATTERN THROUGH THE WEEKEND AND INTO EARLY NEXT WEEK AS RIDGE SHIFTS FROM THE FOUR CORNERS REGION TO THE SOUTHERN PLAINS. AS HEIGHTS INCREASE BY MID WEEK...HIGHS IN THE 90S WILL BECOME COMMON AGAIN. MILLER && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$
AREA FORECAST DISCUSSION
NWS BUFFALO NY
702 PM EDT THU AUG 9 2012 .SYNOPSIS... AN UNUSUALLY STRONG LOW PRESSURE SYSTEM FOR MID AUGUST WILL TRACK FROM THE OHIO VALLEY TO LAKE ERIE TONIGHT...BEFORE SLOWLY LIFTING NORTHEAST ACROSS ONTARIO AND QUEBEC FRIDAY THROUGH SUNDAY. THIS SYSTEM SHOULD BRING SOME MUCH NEEDED RAINFALL TO THE REGION TONIGHT THROUGH SATURDAY MORNING...WITH SOME LAKE EFFECT RAIN SHOWERS THEN POSSIBLY AFFECTING AREAS DOWNWIND OF THE LAKES SATURDAY NIGHT AND SUNDAY. && .NEAR TERM /THROUGH FRIDAY/... THROUGH EARLY EVENING...THE MOST SIGNIFICANT SHOWERS AND THUNDERSTORMS HAVE LARGELY STEERED CLEAR OF OUR CWA IN WESTERN NEW YORK. THIS IS LIKELY TO CHANGE...AS RADAR TRENDS AND THE LATEST HRRR RUNS SUGGESTS HEAVY RAIN WILL STREAM UP A BOUNDARY EXTENDING FROM SW-NE FROM EASTERN OHIO...TO NORTHWESTERN NEW YORK...TO WEST- CENTRAL NEW YORK. FOLLOWING THIS TREND...EXPECT THE GREATEST POTENTIAL FOR HEAVY RAIN WILL BE IN CATTARAUGUS/ALLEGHENY/LIVINGSTON COUNTIES. WHILE STORMS SHOULD GRADUALLY WEAKEN WITH THE LOSS OF DAYTIME HEATING...GIVEN THE UPPER FLOW IS PARALLEL TO THE DEVELOPING LINE...CAN SEE THE POTENTIALLY FOR LOCALLY HEAVY RAINFALL IN EXCESS OF TWO INCHES IN THIS REGION. THIS COULD POSE A THREAT FOR FLASH FLOODING IF THE HRRR FORECAST PANS OUT. UPDATE INCLUDES MENTION OF HEAVY RAINFALL IN THESE COUNTIES...AND PERHAPS IN COUNTIES NEARBY THIS EXPANDING FINGER OF MOISTURE. OTHERWISE...A MORE STRATI-FORM AREA OF SHOWERS ACROSS WESTERN LAKE ONTARIO WILL DRIFT TO THE NORTHEAST. THIS MAY EXPAND AND CLIP WESTERN NEW YORK...BUT FEEL QPFS WITH THIS SHOULD LARGELY BE ON THE LIGHT SIDE COMPARED TO STORMS EXPANDING INTO THE SOUTHERN TIER. AFTER THAT...ACTIVITY SHOULD BECOME MORE WIDESPREAD...BUT ALSO MORE STRATIFORM AS THE MAIN SURFACE WAVE LIFTS NORTHEAST INTO LAKE ERIE...WITH STRENGTHENING WARM AIR ADVECTION AND JET DYNAMICS OUT AHEAD OF THE LOW HELPING TO FORCE THE DEVELOPMENT OF MORE WIDESPREAD SHOWERS ACROSS THE AREA...ALONG WITH SOME EMBEDDED THUNDER GIVEN THE CONTINUED PRESENCE OF ELEVATED INSTABILITY. WILL HAVE POPS INCREASING TO THE LIKELY AND CATEGORICAL RANGES DURING THIS TIME FRAME...WITH THE HIGHEST PRECIP CHANCES FOCUSED NORTH OF THE WARM FRONT...OR ACROSS FAR WESTERN NEW YORK...PORTIONS OF THE GENESEE VALLEY...AND NORTH COUNTRY. DURING THE COURSE OF FRIDAY...THE SURFACE LOW WILL LIFT NORTH INTO SOUTHERN ONTARIO...WITH ITS ASSOCIATED WARM FRONT/BELT OF WARM ADVECTIVE PRECIP GRADUALLY SHIFTING NORTH INTO ONTARIO AND THE SAINT LAWRENCE VALLEY WITH TIME. AT THE SAME TIME...ITS TRAILING COLD FRONT WILL SLIDE EAST INTO FAR WESTERN NEW YORK. COUPLED WITH HEIGHT FALLS AND AN INCREASINGLY DIFFLUENT FLOW ALOFT ASSOCIATED WITH THE APPROACHING PARENT UPPER LEVEL LOW...THIS FEATURE WILL LIKELY SET OFF ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS THAT WILL WORK ACROSS THE AREA FROM WEST TO EAST FRIDAY AFTERNOON. NEEDLESS TO SAY...ALL OF THIS WILL RESULT IN RATHER HIGH PRECIPITATION CHANCES CONTINUING RIGHT THROUGH FRIDAY...WITH A MIX OF HIGH LIKELY TO CATEGORICAL POPS AGAIN IN THE FORECAST. IN TERMS OF SEVERE WEATHER POTENTIAL...THIS SHOULD REMAIN RELATIVELY LOW THIS EVENING WITH THE AREA OF THE GREATEST INSTABILITY REMAINING LARGELY TO OUR SOUTH AND EAST...THOUGH WE WILL STILL NEED TO KEEP AN EYE ON ANY ADDITIONAL CONVECTION THAT POPS ALONG OUR SOUTHEASTERN PERIPHERY. LIKEWISE...DIMINISHING SURFACE-BASED AND MIXED-LAYER INSTABILITY AFTER SUNSET WILL ALSO RESULT IN THE SEVERE WEATHER PROBABILITIES REMAINING VERY LOW TONIGHT. AS FOR FRIDAY...FAIRLY PERSISTENT CLOUD COVER AND MORNING/EARLY AFTERNOON SHOWER ACTIVITY SHOULD HELP TO HOLD INSTABILITY LEVELS DOWN IN ADVANCE OF THE APPROACHING COLD FRONT...WHICH SHOULD HELP TO AGAIN LEAD TO A REDUCED SEVERE RISK. THIS SAID...WE WILL AGAIN NEED TO KEEP AN EYE ACROSS FAR SOUTHERN PORTIONS OF THE AREA FOR ANY BREAKS/POCKETS OF BETTER HEATING THAT COULD LEAD TO LOCALIZED STRONGER CONVECTIVE DEVELOPMENT...ESPECIALLY GIVEN THE PRESENCE OF A MID LEVEL JET ENCROACHING FROM THE SOUTH. AS FOR RAINFALL AMOUNTS...IF CURRENT MODEL PROJECTIONS HOLD TRUE...A CONSENSUS OF THE NAM/GFS/ECMWF AND HPC GUIDANCE SUGGESTS THE POTENTIAL FOR AS MUCH AS ONE TO ONE AND A HALF INCHES OR RAIN THROUGH FRIDAY...WITH THE HIGHEST AMOUNTS MOST LIKELY ACROSS NORTHERN SECTIONS...AND THE LOWEST AMOUNTS MORE PROBABLE ACROSS INTERIOR PORTIONS OF THE SOUTHERN TIER/FINGER LAKES. GIVEN THE DRY WEATHER OF THIS SUMMER...SUCH RAINFALL IS LIKELY TO BE LARGELY BENEFICIAL AND NOT LIKELY TO CAUSE WIDESPREAD FLOODING CONCERNS... THOUGH HIGHLY LOCALIZED FLOODING ISSUES WOULD STILL BE POSSIBLE WITHIN INDIVIDUAL STORMS/STRONGER CONVECTIVE ELEMENTS. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/... SHORT TERM MODELS REMAINING CONSISTENT IN SHOWING A DEEP DRY SLOT SURGING INTO THE REGION ON THE EASTERN SIDE OF THE HIGHLY ANOMALOUS UPPER CIRCULATION. THIS SHOULD EFFECTIVELY DIMINISH THE STEADIEST PRECIPITATION FROM WEST TO EAST FRIDAY NIGHT THROUGH SATURDAY. HOWEVER...WRAP AROUND MOISTURE BEGINS TO WORK INTO WESTERN SECTIONS DURING THE DAY SATURDAY...EVENTUALLY PUSHING THROUGH EASTERN SECTIONS BY SATURDAY NIGHT. THE POTENTIAL FOR LAKE EFFECT/ENHANCED RAINS BECOME INTERESTING SATURDAY NIGHT INTO EARLY SUNDAY... ESPECIALLY OFF LAKE ERIE AS 850 MB DELTA T VALUES NEAR 15C WITH WELL ALIGNED WEST SOUTHWEST TRAJECTORIES. && .LONG TERM /MONDAY THROUGH THURSDAY/... LATEST MEDIUM RANGE MODELS AND ENSEMBLES IN FAIR AGREEMENT THROUGH THE PERIOD WHICH IS BASICALLY TO SUGGEST BROAD UPPER LEVEL TROUGHING ACROSS THE NORTHEAST CONUS...ALTHOUGH THE PERIOD WILL START WITH A PERIOD OF RIDGING. THE WEAK RIDGING ALOFT AND AT THE SURFACE WILL PROVIDE DRY CONDITIONS FOR MONDAY. THIS LOOKS TO BE JUST A BRIEF PERIOD AS ADDITIONAL SHORT WAVE ENERGY DROPS THROUGH THE BROAD TROUGH BY EARLY TUESDAY WITH A RENEWED THREAT FOR CONVECTION LATE MONDAY NIGHT AND TUESDAY. ADDITIONAL CHANCES FOR CONVECTION WILL DEVELOP ALONG AND AHEAD OF THE SURFACE COLD FRONT DROPPING DOWN ACROSS THE REGION LATE TUESDAY NIGHT AND WEDNESDAY. HIGH PRESSURE NOSING DOWN IN WAKE OF THE FRONT SHOULD BRING DRIER CONDITIONS FOR THURSDAY. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... AREA RADARS SHOWING SCATTERED POCKETS OF RAIN SHOWERS CONTINUING TO MOVE NORTHEASTWARD THROUGH PORTIONS OF WESTERN AND NORTHERN NEW YORK THIS AFTERNOON. AN AREA OF CLEARING WILL BRIEFLY MOVE INTO WESTERN AND NORTHERN NEW YORK DURING THE MID TO LATE AFTERNOON HOURS PROVIDING MAINLY VFR CONDITIONS...HOWEVER THIS ADDITIONAL HEATING WILL TEND TO MAKE THINGS A BIT MORE UNSTABLE AND POSSIBLY LEAD TO THE DEVELOPMENT OF SOME ISOLATED THUNDERSTORM ACTIVITY. CIGS WILL THEN THICKEN AND LOWER AGAIN LATER THIS EVENING. VFR CONDITIONS ARE EXPECTED THROUGH THE EVENING...THEN POSSIBLY GOING MVFR AT TIMES DURING THE OVERNIGHT HOURS. STEADIER RAIN/MVFR CONDITIONS AFTER 06Z WILL TAPER OFF TO SCATTERED SHOWERS LATER IN THE MORNING/EARLY AFTERNOON. OUTLOOK... FRIDAY NIGHT...MVFR IN SCATTERED SHOWERS. SATURDAY...VFR/MVFR IN SCATTERED SHOWERS. SUNDAY...MAINLY VFR. MONDAY...VFR. TUESDAY...VFR...CHANCE OF SHOWERS. && .MARINE... AN UNUSUALLY STRONG LOW PRESSURE SYSTEM FOR MID AUGUST WILL TRACK FROM THE OHIO VALLEY TO LAKE ERIE TONIGHT...BEFORE SLOWLY LIFTING NORTHEAST ACROSS ONTARIO AND QUEBEC FRIDAY THROUGH SUNDAY. THIS SYSTEM WILL KEEP UNSETTLED WEATHER ACROSS THE LOWER LAKES REGION THROUGH THE UPCOMING WEEKEND. IN TERMS OF WINDS AND WAVES...A MORE NORTHWESTERLY TRACK OF THE LOW COMPARED TO EARLIER PROJECTIONS WILL LEAD TO A SOMEWHAT WEAKER EASTERLY TO NORTHEASTERLY FLOW ON LAKE ONTARIO LATER TONIGHT AND FRIDAY MORNING...WHICH SHOULD RESULT IN CONDITIONS REMAINING BELOW SMALL CRAFT ADVISORY CRITERIA THROUGH THAT TIME. WINDS WILL THEN VEER TO SOUTHERLY ON FRIDAY FOLLOWING THE PASSAGE OF A WARM FRONT...BEFORE TURNING SOUTHWESTERLY AND STRENGTHENING FRIDAY NIGHT AND SATURDAY IN THE WAKE OF A COLD FRONT. COUPLED WITH THE ARRIVAL OF COOLER AIR ALOFT...THIS MAY LEAD TO ADVISORY-LEVEL CONDITIONS DEVELOPING ACROSS PORTIONS OF THE LAKES FRIDAY NIGHT AND SATURDAY. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...NONE. && $$ SYNOPSIS...JJR NEAR TERM...APFFEL/JJR SHORT TERM...TMA LONG TERM...TMA AVIATION...JM/SMITH MARINE...JJR
AREA FORECAST DISCUSSION
NWS BUFFALO NY
543 PM EDT WED AUG 8 2012 .SYNOPSIS... A WEAK COLD FRONT WILL MOVE ACROSS OUR AREA BY EARLY THIS EVENING...WITH SCATTERED SHOWERS AND THUNDERSTORMS ACCOMPANYING ITS PASSAGE. MAINLY DRY WEATHER WILL THEN FOLLOW THE FRONT TONIGHT... BEFORE LOW PRESSURE LIFTS NORTHEAST FROM THE OHIO VALLEY THURSDAY AND FRIDAY AND BRINGS INCREASINGLY UNSETTLED CONDITIONS. && .NEAR TERM /THROUGH THURSDAY/... AS OF 2100Z...A SLOW MOVING FRONTAL BOUNDARY WAS JUST SOUTH OF A BUFFALO TO ROCHESTER TO WATERTOWN LINE. THIS CAN BE SEEN BOTH WITH SURFACE OBSERVATIONS...AND THE BOUNDARY SHOWS UP VERY NICELY ON THE MONTAGUE RADAR. THIS FRONT COMBINED WITH LAKE BREEZES HAS SPAWNED SOME SHOWERS AND THUNDERSTORMS OUT AHEAD OF THE BOUNDARY. THE HRRR CAPTURES THIS QUITE WELL...AND SUGGESTS A WEAKENING TREND AS THESE CELLS MOVE TO THE EAST AT ABOUT 20 MPH. GRIDS AND ZONES WERE UPDATED TO REFLECT THE LATEST RADAR TRENDS. FOLLOWING THE PASSAGE OF THE FRONT...THE LOSS OF BOTH LOW LEVEL CONVERGENCE AND DAYTIME HEATING SHOULD BRING AN END TO THE PRECIP DURING THE EARLY TO MID EVENING HOURS...WITH GENERALLY DRY WEATHER THEN EXPECTED TO FOLLOW FOR THE BALANCE OF THE NIGHT. WITH SCATTERED LOWER CLOUDS REMAINING IN PLACE AND MID AND HIGH CLOUDS INCREASING OVERNIGHT IN ADVANCE OF THE NEXT LOW...AT THIS POINT DO NOT EXPECT FOG TO BE A SIGNIFICANT FORECAST CONCERN OVERNIGHT. ON THURSDAY...CLOUDS WILL CONTINUE TO INCREASE AND THICKEN ACROSS THE AREA FROM SOUTHWEST TO NORTHEAST AS UPPER TROUGHING TAKES SHAPE ACROSS THE GREAT LAKES...AND AN ATTENDANT SURFACE LOW DEVELOPS AND LIFTS NORTHEAST ACROSS THE OHIO VALLEY. WITH DIURNAL HEATING...THE FRONTAL BOUNDARY STALLED OUT JUST TO OUR SOUTH MAY BECOME THE FOCUS FOR ANOTHER ROUND OF SCATTERED CONVECTION ACROSS THE SOUTHERN TIER AND FINGER LAKES DURING THE AFTERNOON...BEFORE THE MAIN SURFACE WAVE DRAWS CLOSE ENOUGH TO BRING INCREASING SHOWER/THUNDERSTORM CHANCES TO THE REST OF THE REGION LATER IN THE DAY. WILL CONTINUE TO INDICATE A NORTHEAST-SOUTHWEST GRADIENT IN PRECIP CHANCES ACROSS THE REGION TOMORROW AFTERNOON...RANGING FROM SLIGHT CHANCE/LOW CHANCE ACROSS THE SAINT LAWRENCE VALLEY AND NORTH COUNTRY...TO HIGH CHANCE ACROSS THE SOUTHERN TIER AND FAR WESTERN NEW YORK. WITH THE BEST INSTABILITY REMAINING ALONG AND SOUTH OF THE FRONT AND ANY STRONGER WIND FIELDS ALOFT REMAINING TO ITS NORTH...AT THIS POINT OUR SEVERE WEATHER POTENTIAL FOR TOMORROW AFTERNOON LOOKS TO BE RELATIVELY LOW. AS FOR TEMPERATURES...READINGS WILL AGAIN BE A LITTLE MILDER TONIGHT THAN LAST NIGHT...WITH LOWS RANGING FROM THE UPPER 50S/NEAR 60 ACROSS INTERIOR PORTIONS OF THE SOUTHERN TIER AND NORTH COUNTRY TO THE MID 60S ACROSS THE LAKE PLAINS. WITH 850 MB TEMPS OF +14C TO +16C AND INCREASING CLOUD COVER/PRECIP CHANCES THEN EXPECTED ON THURSDAY...DAYTIME HIGHS SHOULD RANGE FROM THE LOWER TO MID 80S IN MOST LOCATIONS. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/... MUCH NEEDED BENEFICIAL RAINS CONTINUING TO LOOK PROMISING DURING THE THURSDAY NIGHT THROUGH FRIDAY NIGHT TIME FRAME...AS POTENT UPPER LEVEL LOW DROPS THROUGH THE GREAT LAKES. NAM/CANADIAN/GFS ALL ON BOARD IN CONTINUING TO DEVELOP INCREASING RAIN AREA...ALONG WITH SOME EMBEDDED STRONGER CONVECTION WITH THE INCREASING MID LEVEL FRONTOGENESIS AND SUBSTANTIAL HEIGHT FALLS TAKING PLACE. PRECIPITATION PATTERN LOOKS TO BECOME EVEN MORE FOCUSED LATE THURSDAY NIGHT AND FRIDAY. THE LOW/MID LEVEL BAROCLINIC ZONE EXTENDING ACROSS NEW YORK STATE WILL UNDERGO SIGNIFICANT FRONTOGENESIS AND DEEPEN IN RESPONSE TO INCREASING UPPER LEVEL DIVERGENCE AND INTENSE LARGE SCALE ASCENT JUST AHEAD OF THE PV ANOMALY...ALLOWING RAIN/EMBEDDED THUNDER TO INCREASE IN COVERAGE/INTENSITY. PLACEMENT OF HEAVIEST PRECIPITATION AXIS WILL BE A TOUGH CALL WITH STILL SOME MODEL DISCREPANCIES IN THE EXACT TRACK OF THE UPPER LEVEL LOW AND SUBSEQUENT SURFACE WAVE...AS WELL AS A MODEL AGREEMENT OF THE PRESENCE OF A SHARP DRY SLOT NOSING INTO A PORTION OF THE AREA. PRECIPITABLE WATER VALUES ACROSS THE ENTIRE AREA WILL BE RUNNING IN THE 1.5 TO 1.75 INCH RANGE. EXPECTATIONS ARE THAT A GENERAL WIDESPREAD 0.75 TO 1.25 INCHES OF RAIN WILL OCCUR...WITH HEAVIER AMOUNTS NEARING 2 INCHES VERY POSSIBLE ACROSS EASTERN SECTIONS OF THE AREA WHERE MODELS DO NOT PLACE ANY SIGNIFICANT DRY SLOTTING. THE STEADIEST PRECIPITATION SHOULD DROP OF FRIDAY NIGHT AND SATURDAY AS DEEP DRY SLOT WORKS INTO THE AREA BEHIND THE LOW AS IT PUSHES INTO ONTARIO. HOWEVER...WRAP AROUND MOISTURE BEGINS TO WORK INTO WESTERN SECTIONS DURING THE DAY SATURDAY...EVENTUALLY PUSHING THROUGH EASTERN SECTIONS BY SATURDAY NIGHT. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... HEIGHTS BEGIN TO RISE IN THE WAKE OF THE UPPER LOW FOR THE SECOND HALF OF THE WEEKEND. A LINGERING CYCLONIC FLOW OVER EASTERN SECTIONS OF THE AREA COULD TOUCH OFF A FEW SHOWERS...OTHERWISE THE OVERALL TREND IS TO DRY THINGS OUT FROM WEST TO EAST. HEIGHTS CONTINUING TO RISE THROUGH MID WEEK. FOR THE MOST PART EXPECT DRY WEATHER... ALTHOUGH GLOBAL MODELS SUGGESTING A COUPLE OF WEAK SHORT WAVES CROSSING THE REGION IN THE NORTHWEST FLOW ALOFT. HOWEVER...THESE MODELS DIFFER IN INTENSITY AND TRACK OF THE INDIVIDUAL WAVE WAND CONFIDENCE IS LOW THAT MUCH ACTIVITY WILL BE GENERATED...OTHER THAN SOME SPOTTY DIURNALLY DRIVEN CONVECTION. && .AVIATION /21Z WEDNESDAY THROUGH MONDAY/... AS OF 2100Z...THE SLOW-MOVING COLD FRONTAL BOUNDARY IS DRAPED ACROSS THE LOWER GREAT LAKES AND FAR WESTERN NEW YORK. THE FRONT IS ALREADY THROUGH ALL TAF LOCATIONS...WITH A MINIMAL CHANCE FOR THUNDERSTORMS FOR THE REMAINDER OF THE EVENING. ONCE THE FRONT PASSES THROUGH THE AREA...EXPECT A GRADUAL INCREASE IN MID AND HIGH LEVEL CLOUDINESS EXPECTED OVERNIGHT. COUPLED WITH LINGERING SCATTERED LOWER VFR CLOUDS...THESE SHOULD HELP REDUCE THE RISK OF FOG OVERNIGHT. ON THURSDAY...CLOUD COVER WILL CONTINUE TO THICKEN ACROSS THE AREA THROUGH THE DAY IN ADVANCE OF LOW PRESSURE LIFTING NORTHEAST ACROSS THE OHIO VALLEY. EXPECT THE MORNING TO BE LARGELY DRY...WITH CONVECTIVE CHANCES THEN SLOWLY INCREASING DURING THE AFTERNOON AS THE LOW APPROACHES THE AREA AND DAYTIME INSTABILITY DEVELOPS. AS THE BULK OF ANY PRECIP WILL BE SCATTERED INITIALLY AND SHOULD HOLD OFF UNTIL CLOSE TO OR AFTER 18Z...FOR NOW HAVE ELECTED TO LEAVE THE TAFS DRY LATE IN THE PERIOD. OUTLOOK... THURSDAY NIGHT AND FRIDAY...IFR/MVFR IN RAIN WITH SCATTERED THUNDERSTORMS. SATURDAY...VFR/MVFR WITH A CHANCE OF SHOWERS AND THUNDERSTORMS. SUNDAY...MAINLY VFR. MONDAY...VFR. && .MARINE... A WEAK COLD FRONT WILL MOVE FINISH CROSSING THE LOWER LAKES BY EARLY THIS EVENING... WITH SCATTERED SHOWERS AND THUNDERSTORMS ACCOMPANYING ITS PASSAGE. MAINLY DRY WEATHER WILL THEN FOLLOW THE FRONT TONIGHT...BEFORE LOW PRESSURE LIFTS NORTHEAST FROM THE OHIO VALLEY THURSDAY AND FRIDAY AND BRINGS INCREASINGLY UNSETTLED CONDITIONS...INCLUDING THE THREAT OF SCATTERED THUNDERSTORMS. IN TERMS OF WINDS AND WAVES...GENERALLY LIGHT TO MODEST WINDS TO CONTINUE THROUGH THURSDAY...WITH WAVES REMAINING UNDER 2 FEET. AFTER THAT TIME...A STRENGTHENING NORTH TO NORTHEASTERLY FLOW WILL BRING A RISK OF ADVISORY LEVEL WINDS AND WAVES TO WESTERN LAKE ONTARIO BY FRIDAY MORNING. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...NONE. && $$ SYNOPSIS...JJR NEAR TERM...APFFEL/JJR SHORT TERM...TMA LONG TERM...TMA AVIATION...JJR MARINE...JJR
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1050 PM EDT THU AUG 9 2012 .SYNOPSIS... A TROUGH OF LOW PRESSURE OVER THE PIEDMONT THIS AFTERNOON THROUGH FRIDAY WILL GIVE WAY TO A COLD FRONT ON SATURDAY. HIGH PRESSURE WILL BUILD INTO THE AREA EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1045 PM THURSDAY...CONTINUED MAIN DILEMMA FOR THE OVERNIGHT PERIOD WILL BE THE TIMING AND COVERAGE OF THE CONVECTIVE ACTIVITY APPROACHING FROM THE SOUTHWEST. VARIOUS MODEL BUFR SOUNDINGS INDICATE AN INCREASE IN MOISTURE THIS EVENING AND OVERNIGHT VIA PWS REBOUNDING BACK OVER 2+ INCHES. WEAK MID LEVEL SHEARED VORT AND AN UPPER LEVEL JET MAX TO TRACK NE ACROSS THE CAROLINAS TONIGHT...WITH THE RIGHT REAR QUADRANT OF THIS UPPER JET AND SOURCE OF UPPER LEVEL DIVERGENCE TO PUSH ACROSS OR AFFECT THE FA MAINLY AFTER MIDNIGHT TONIGHT. THE RR QUAD WILL BE A FAVORED AREA OF UVVS AND AS A RESULT WILL INCREASE POPS TO GOOD CHANCE OR POSSIBLY LIKELY LEADING TO BUT MAINLY OCCURRING AFTER MIDNIGHT TONIGHT. THE DAYS HEATING COMBINED WITH DYNAMICS ALOFT HAS HELPED CONVECTION REACH SVR CRITERIA WELL UPSTREAM FROM THE FA. THE DAYS INSOLATION WILL BE DONE-WITH BY THE TIME THE BULK OF THE PCPN PUSHES TO/ACROSS THE ILM CWA LATER TONIGHT...AND AS A RESULT DO NOT ANTICIPATE PULSING SVR ACTIVITY. HOWEVER...DO LIKE THE HEAVY RAIN/GUSTY WINDS TO SUFFIX AFTER THE MENTIONING OF THE CONVECTION OVERNIGHT. EXPECT 20-30 MPH STORM MOTIONS...WHICH SHOULD HELP LOWER THE FLOOD POTENTIAL. HOWEVER...IF ACTIVITY BEGINS TO TRAIN...THEN WILL HAVE TO REVISIT THE FLOOD ISSUE. AS FOR MIN TEMPS...WILL STAY ON THE HIGHER SIDE OF MOS GUIDANCE DUE TO SKIES HAVING CLOUDED UP ALONG WITH THE POTENTIAL MORNING OCCURRENCE OF PCPN. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 2 PM THURSDAY...AN AMPLIFYING H5 TROUGH...APPROACHING COLD FRONT AND PRECIPITABLE WATER SURGING ABOVE 2 INCHES WILL RESULT IN AN UNSETTLED SHORT TERM PERIOD. THE FRONT IS EXPECTED TO STALL IN THE VICINITY AS IT BECOMES ORIENTED WITH THE FLOW ALOFT. THUS THE FORECAST INDICATES CHANCE TO LIKELY POPS THROUGH SATURDAY NIGHT. FAVORED THE COOLER MET NUMBERS EACH DAY GIVEN THE EXPECTED CLOUD COVER. THE CLOUD COVER COULD ALSO LIMIT DEEPER CONVECTION FROM DEVELOPING...HOWEVER HEATING WILL LIKELY LEAD TO AT LEAST MODERATE INSTABILITY. && .LONG TERM /SUNDAY THROUGH THURSDAY/... AS OF 2 PM THURSDAY...COLD FRONT WILL BE MOVING OFFSHORE WHILE DISSIPATING AT THE START OF THE PERIOD. THIS WILL BRING AN END TO PRECIP THROUGH SUNDAY AFTN AS DRIER AND COOLER AIR WORKS IN BEHIND THIS BOUNDARY. FORECAST SOUNDINGS SUGGEST CLEARING WILL OCCUR RAPIDLY DURING SUNDAY...BUT EVEN WITH AMPLE SUNSHINE...TEMPS WILL STRUGGLE TO CLIMO AS SOME COOL ADVECTION OCCURS THROUGH MAX HEATING. EXPECT TEMPS AT OR JUST BELOW 90 SUNDAY WITH MINS FALLING TO NEAR 70. UPPER TROUGH WEAKENS AND SPINS OFF TO THE NORTHEAST AS SUBTLE RIDGING DEVELOPS ACROSS THE SOUTHEAST. RISING 1000-500MB THICKNESSES AND WARMING MID-LEVEL TEMPS WILL COMBINE WITH DRY W/NW FLOW TO PREVENT WIDESPREAD CONVECTION MON EVEN WITH SLIGHTLY STEEPENED ML LAPSE RATES. MOISTURE RETURN IS SLOW TO DEVELOP TUESDAY...BUT SOME GUIDANCE INDICATING THAT A COASTAL TROUGH MAY HELP SPREAD SOME MOISTURE TOWARDS THE COAST AND WILL BUMP POP TO CHC TUESDAY...ACROSS THE EAST. TEMPS WILL REMAIN AROUND CLIMO...A FEW DEGREES EITHER SIDE OF 90 AND 70. FOR THE MID/LATE WEEK...BROAD TROUGHING REMAINS ACROSS THE EAST WHILE WEAK IMPULSES MAY SPAWN AFTERNOON STORMS EACH DAY. HOWEVER...WITH MID LEVEL DRY AIR PERSISTING...CONVECTION WILL BE CAPPED AT SCHC/SILENT THIS FAR OUT IN TIME. A REINFORCING SHOT OF COOL/DRY AIR MAY PUSH THROUGH THURSDAY AS UPPER VORT MOVES ACROSS NEW ENGLAND WHICH WILL HELP KEEP TEMPS RIGHT AROUND CLIMO THROUGH THE END OF THE PERIOD. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... AS OF 00Z...EXPECT TSRA AT FLO/MYR/CRE AND RW AT LBT AROUND 04Z AS PRECIP MOVES IN FROM THE SW. CONFIDENCE IN TIMING NOT REAL HIGH. PRECIP MOVS NE W/BEST CHC TSRA NR ILM 09Z. TEMPO MVFR LIKELY WITH PRECIP. WILL NOT INCLUDE IFR DUE TO SCT NATURE OF ACTIVITY...BUT SHORT TERM IFR PSBL IF CELL MOVES OVR A TERM. AT FLO/LBT MVFR CIGS/VSBYS IN BR 08-09Z. PRECIP RE-DEVELOPS BTWN COAST TERMS AND INLAND TERMS BY 18Z. MOD CONFIDENCE TEMPO IFR/TS PSBL MAINLY COAST TERMS 18-00Z AS SHORT WAVE MOVS THROUGH. LOW CONFIDENCE TS AT FLO/LBT 18-00Z. EXTENDED OUTLOOK...CHANCE OF MORNING MVFR VSBYS IN BR WITH A CHANCE OF SHOWERS AND THUNDERSTORMS THROUGH SUNDAY. VFR MONDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 1045 PM THURSDAY...PROGGED SFC PRESSURE PATTERN AND TIGHTENING GRADIENT...WILL YIELD WINDS FROM SSW-SW THIS EVENING AND OVERNIGHT...ALONG WITH SPEEDS INCREASING FROM AROUND 15 KT...EXCEPT 15-20 KT FOR THE ILM NC WATERS. SIGNIFICANT SEAS ...MAINLY FROM WIND DRIVEN 3-5 SECOND PERIOD WAVES...WILL BUILD TO 3 TO 5 FT NORTH OF LITTLE RIVER INLET...AND 2 TO 4 FT SOUTH OF THE INLET. SEAS ARE EXPECTED TO BUILD TO 4 TO 6 FT FOR THE ILM NC WATERS FRIDAY...WITH SW WINDS 15-20 KT. STILL NOT ALL THAT CONFIDENT AT THE MOMENT WITH REGARD TO RAISING A SCA/SCEC. IF DATA FROM TONIGHTS 00Z EARLY MODEL RUNS INDICATE THIS INCREASED SCA POTENTIAL...MAY GO AHEAD AND ISSUE A SCA OR SCEC AT THE LATE NIGHT UPDATE. SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 2 PM THURSDAY...SOUTH-SOUTHWEST FETCH WILL BE IN PLACE THROUGH THE BULK OF THE SHORT TERM PERIOD. IT APPEARS THE PRESSURE GRADIENT WILL BE AT ITS GREATEST LATE FRIDAY AFTERNOON INTO THE EVENING. THE FLOW WILL FINALLY BEGIN TO WEAKEN SATURDAY NIGHT WITH THE FRONT IN THE VICINITY. SEAS MAY REACH MARGINAL SMALL CRAFT THRESHOLDS BY FRIDAY EVENING...WITH EXERCISE CAUTION CONDITIONS EXPECTED DURING THE MAJORITY OF THE PERIOD. LONG TERM /SUNDAY THROUGH TUESDAY/... AS OF 2 PM THURSDAY...PREDOMINANT SW FLOW TO PERSIST THROUGH THE EXTENDED AS BERMUDA HIGH RIDGES IN FROM THE EAST. A FAIRLY WEAK PRESSURE GRADIENT WILL EXIST HOWEVER...SO WINDS WILL BE AROUND 10 KTS OR LESS THROUGH MUCH OF THE PERIOD. THE LIGHT WINDS WILL PRODUCE A 2-3FT/5SEC SW WIND CHOP WHICH WILL COMBINE WITH A 2FT/9SEC SE SWELL TO PRODUCE OVERALL WAVE HEIGHTS OF 2-3 FT. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ NEAR TERM...DOUGH SHORT TERM...STEVE LONG TERM...JOSH AVIATION...JOSHUA
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
655 PM EDT THU AUG 9 2012 .SYNOPSIS... A TROUGH OF LOW PRESSURE OVER THE PIEDMONT THIS AFTERNOON THROUGH FRIDAY WILL GIVE WAY TO A COLD FRONT ON SATURDAY. HIGH PRESSURE WILL BUILD INTO THE AREA EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 645 PM THURSDAY...MAIN DILEMMA FOR THE TONIGHT PERIOD WILL BE THE TIMING AND COVERAGE OF THE CONVECTIVE ACTIVITY APPROACHING FROM THE SOUTHWEST. VARIOUS MODEL BUFR SOUNDINGS INDICATE AN INCREASE IN MOISTURE THIS EVENING AND OVERNIGHT VIA PWS REBOUNDING BACK OVER 2+ INCHES. WEAK MID LEVEL SHEARED VORT AND AN UPPER LEVEL JET MAX TO TRACK NE ACROSS THE CAROLINAS TONIGHT...WITH THE RIGHT REAR QUADRANT OF THIS UPPER JET AND SOURCE OF UPPER LEVEL DIVERGENCE TO PUSH ACROSS OR AFFECT THE FA MAINLY AFTER MIDNIGHT TONIGHT. THE RR QUAD WILL BE A FAVORED AREA OF UVVS AND AS A RESULT WILL INCREASE POPS TO GOOD CHANCE OR POSSIBLY LIKELY LEADING TO BUT MAINLY OCCURRING AFTER MIDNIGHT TONIGHT. THE DAYS HEATING COMBINED WITH DYNAMICS ALOFT HAS HELPED CONVECTION REACH SVR CRITERIA WELL UPSTREAM FROM THE FA. THE DAYS INSOLATION WILL BE DONE-WITH BY THE TIME THE BULK OF THE PCPN PUSHES TO/ACROSS THE ILM CWA LATER TONIGHT...AND AS A RESULT DO NOT ANTICIPATE PULSING SVR ACTIVITY. HOWEVER DO LIKE THE HEAVY RAIN/GUSTY WINDS TO SUFFIX AFTER THE MENTIONING OF CONVECTION OVERNIGHT. EXPECT 10-15 MPH STORM MOTIONS...WHICH SHOULD HELP LOWER THE FLOOD POTENTIAL. HOWEVER...IF ACTIVITY BEGINS TO TRAIN...THEN WILL HAVE TO REVISIT THE FLOODING ISSUE. AS FOR MIN TEMPS...WILL STAY ON THE HIGHER SIDE OF MOS GUIDANCE DUE TO SKIES CLOUDING UP ALONG WITH THE OCCURRENCE OF PCPN. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 2 PM THURSDAY...AN AMPLIFYING H5 TROUGH...APPROACHING COLD FRONT AND PRECIPITABLE WATER SURGING ABOVE 2 INCHES WILL RESULT IN AN UNSETTLED SHORT TERM PERIOD. THE FRONT IS EXPECTED TO STALL IN THE VICINITY AS IT BECOMES ORIENTED WITH THE FLOW ALOFT. THUS THE FORECAST INDICATES CHANCE TO LIKELY POPS THROUGH SATURDAY NIGHT. FAVORED THE COOLER MET NUMBERS EACH DAY GIVEN THE EXPECTED CLOUD COVER. THE CLOUD COVER COULD ALSO LIMIT DEEPER CONVECTION FROM DEVELOPING...HOWEVER HEATING WILL LIKELY LEAD TO AT LEAST MODERATE INSTABILITY. && .LONG TERM /SUNDAY THROUGH THURSDAY/... AS OF 2 PM THURSDAY...COLD FRONT WILL BE MOVING OFFSHORE WHILE DISSIPATING AT THE START OF THE PERIOD. THIS WILL BRING AN END TO PRECIP THROUGH SUNDAY AFTN AS DRIER AND COOLER AIR WORKS IN BEHIND THIS BOUNDARY. FORECAST SOUNDINGS SUGGEST CLEARING WILL OCCUR RAPIDLY DURING SUNDAY...BUT EVEN WITH AMPLE SUNSHINE...TEMPS WILL STRUGGLE TO CLIMO AS SOME COOL ADVECTION OCCURS THROUGH MAX HEATING. EXPECT TEMPS AT OR JUST BELOW 90 SUNDAY WITH MINS FALLING TO NEAR 70. UPPER TROUGH WEAKENS AND SPINS OFF TO THE NORTHEAST AS SUBTLE RIDGING DEVELOPS ACROSS THE SOUTHEAST. RISING 1000-500MB THICKNESSES AND WARMING MID-LEVEL TEMPS WILL COMBINE WITH DRY W/NW FLOW TO PREVENT WIDESPREAD CONVECTION MON EVEN WITH SLIGHTLY STEEPENED ML LAPSE RATES. MOISTURE RETURN IS SLOW TO DEVELOP TUESDAY...BUT SOME GUIDANCE INDICATING THAT A COASTAL TROUGH MAY HELP SPREAD SOME MOISTURE TOWARDS THE COAST AND WILL BUMP POP TO CHC TUESDAY...ACROSS THE EAST. TEMPS WILL REMAIN AROUND CLIMO...A FEW DEGREES EITHER SIDE OF 90 AND 70. FOR THE MID/LATE WEEK...BROAD TROUGHING REMAINS ACROSS THE EAST WHILE WEAK IMPULSES MAY SPAWN AFTERNOON STORMS EACH DAY. HOWEVER...WITH MID LEVEL DRY AIR PERSISTING...CONVECTION WILL BE CAPPED AT SCHC/SILENT THIS FAR OUT IN TIME. A REINFORCING SHOT OF COOL/DRY AIR MAY PUSH THROUGH THURSDAY AS UPPER VORT MOVES ACROSS NEW ENGLAND WHICH WILL HELP KEEP TEMPS RIGHT AROUND CLIMO THROUGH THE END OF THE PERIOD. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... AS OF 00Z...EXPECT TSRA AT FLO/MYR/CRE AND RW AT LBT AROUND 04Z AS PRECIP MOVES IN FROM THE SW. CONFIDENCE IN TIMING NOT REAL HIGH. PRECIP MOVS NE W/BEST CHC TSRA NR ILM 09Z. TEMPO MVFR LIKELY WITH PRECIP. WILL NOT INCLUDE IFR DUE TO SCT NATURE OF ACTIVITY...BUT SHORT TERM IFR PSBL IF CELL MOVES OVR A TERM. AT FLO/LBT MVFR CIGS/VSBYS IN BR 08-09Z. PRECIP RE-DEVELOPS BTWN COAST TERMS AND INLAND TERMS BY 18Z. MOD CONFIDENCE TEMPO IFR/TS PSBL MAINLY COAST TERMS 18-00Z AS SHORT WAVE MOVS THROUGH. LOW CONFIDENCE TS AT FLO/LBT 18-00Z. EXTENDED OUTLOOK...CHANCE OF MORNING MVFR VSBYS IN BR WITH A CHANCE OF SHOWERS AND THUNDERSTORMS THROUGH SUNDAY. VFR MONDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 645 PM THURSDAY...PROGGED SFC PRESSURE PATTERN AND TIGHTENING GRADIENT...WILL PRODUCE WINDS VEERING TO THE SSW-SW THIS EVENING AND OVERNIGHT...ALONG WITH SPEEDS INCREASING TO AROUND 15 KT...EXCEPT 15-20 KT FOR THE ILM NC WATERS...AFTER MIDNIGHT. SIGNIFICANT SEAS ...MAINLY FROM WIND DRIVEN 3-5 SECOND PERIOD WAVES...WILL BUILD TO 3 TO 5 FT NORTH OF LITTLE RIVER INLET...AND 2 TO 4 FT SOUTH OF THE INLET. SEAS ARE EXPECTED TO BUILD TO 4 TO 6 FT FOR THE ILM NC WATERS FRIDAY...WITH SW WINDS 15-20 KT. STILL NOT ALL THAT CONFIDENT AT THE MOMENT WITH REGARD TO RAISING A SCA/SCEC. IF DATA FROM TONIGHTS 00Z EARLY MODEL RUNS INDICATE THIS INCREASED SCA POTENTIAL...MAY GO AHEAD AND ISSUE A SCA OR SCEC AT THE LATE NIGHT UPDATE. SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 2 PM THURSDAY...SOUTH-SOUTHWEST FETCH WILL BE IN PLACE THROUGH THE BULK OF THE SHORT TERM PERIOD. IT APPEARS THE PRESSURE GRADIENT WILL BE AT ITS GREATEST LATE FRIDAY AFTERNOON INTO THE EVENING. THE FLOW WILL FINALLY BEGIN TO WEAKEN SATURDAY NIGHT WITH THE FRONT IN THE VICINITY. SEAS MAY REACH MARGINAL SMALL CRAFT THRESHOLDS BY FRIDAY EVENING...WITH EXERCISE CAUTION CONDITIONS EXPECTED DURING THE MAJORITY OF THE PERIOD. LONG TERM /SUNDAY THROUGH TUESDAY/... AS OF 2 PM THURSDAY...PREDOMINANT SW FLOW TO PERSIST THROUGH THE EXTENDED AS BERMUDA HIGH RIDGES IN FROM THE EAST. A FAIRLY WEAK PRESSURE GRADIENT WILL EXIST HOWEVER...SO WINDS WILL BE AROUND 10 KTS OR LESS THROUGH MUCH OF THE PERIOD. THE LIGHT WINDS WILL PRODUCE A 2-3FT/5SEC SW WIND CHOP WHICH WILL COMBINE WITH A 2FT/9SEC SE SWELL TO PRODUCE OVERALL WAVE HEIGHTS OF 2-3 FT. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ NEAR TERM...DOUGH SHORT TERM...STEVEP LONG TERM...JOSHW AVIATION...MIKER
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
610 PM EDT WED AUG 8 2012 .SYNOPSIS... SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE THROUGH THE EVENING. ONLY WIDELY SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED THURSDAY WITH BETTER CHANCES EXPECTED FRIDAY. A COLD FRONT WILL ALLOW THE CHANCE OF STORMS TO CONTINUE ON SATURDAY. HIGH PRESSURE WILL BUILD INTO THE AREA EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 6:00 PM WEDNESDAY...HAVE FIRED OUT A QUICK UPDATE TO GO WITH CATEGORICAL POPS FOR NORTHWESTERN COUNTIES AS CONVECTION APPEARS TO BE ORGANIZING. HRRR HAS THE ACTIVITY CAPTURED WELL AND MAINTAINS IT FOR SEVERAL HOURS. DAYTIME HEATING HAS ALLOWED THE TEMPERATURES TO RISE TO THE UPPER 80S IN THESE AREAS PROVIDING AMPLE SURFACE BASED INSTABILITY. HRRR/1800 UTC GFS AND NAM SHOW THIS WILL BE ALL THE ACTIVITY AND THEREFORE REMOVED POPS FOR THE REMAINDER OF THE AREA AFTER AROUND 0400 UTC. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 3 PM WEDNESDAY...THE NEXT H5 TROUGH WILL DEVELOP ACROSS THE MS VALLEY THU AS AN UPPER LOW DIVES SOUTH FROM THE WESTERN GREAT LAKES REGION. THE RESULT WILL BE A HIGHLY AMPLIFIED/ANOMALOUS TROUGH ALOFT OVER THE EASTERN UNITED STATES BY FRIDAY. THE TROUGH WILL PUSH A COLD FRONT TOWARD THE FORECAST AREA LATE FRIDAY. THE PRECIPITABLE WATER WILL ALSO INCREASE TO 2+INCHES FRIDAY AHEAD OF THE FRONT ALONG WITH SUFFICIENT INSTABILITY THE BETTER BET FOR TSTMS DURING THE SHORT TERM PERIOD WILL BE FRIDAY. CURRENTLY THE FORECAST AREA IS IN A SLIGHT RISK FOR SEVERE TSTMS FRIDAY...BUT ULTIMATELY IT MAY DEPEND ON THE AMOUNT OF CLOUD COVER WHICH COULD IMPEDE DESTABILIZATION. OTHERWISE...FAVORED A BLEND OF MAV/MET NUMBERS EACH PERIOD. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... AS OF 3 PM WEDNESDAY...IN A PATTERN MORE COMMONLY SEEN IN NOVEMBER THAN MID-AUGUST...A HIGHLY ANOMALOUS 500MB TROUGH SPINS ACROSS THE GREAT LAKES BEFORE ROTATING OFF TO THE NORTHEAST DURING THE EARLY PART OF THE WEEK. AS THIS TROUGH SLOWLY SPINS AWAY...IT DRAGS A COLD FRONT ACROSS THE AREA. GUIDANCE IN DECENT AGREEMENT ON TIMING OF THIS FRONT...AND EXPECT FROPA TO OCCUR VERY EARLY SUNDAY. MOST SIGNIFICANT WEATHER OF THE EXTENDED WILL OCCUR SATURDAY AS FRONT PUSHES ACROSS THE AREA...DISPLACING THE WARM SECTOR AIRMASS. ATTM SPC HAS NO PORTION OF OUR REGION OUTLOOKED IN DAY 4...BUT WOULD NOT BE SURPRISED IF A SLIGHT RISK OR SEE TEXT IS INTRODUCED WITH LATER UPDATES AS FRONT WORKS INTO A MODERATELY UNSTABLE AIRMASS WITH DECENT NEARLY UNIDIRECTIONAL SHEAR AND HIGH PWATS. ADDITIONALLY...GFS/EURO SHOW STRONG PVA ASSOCIATED WITH A VORT LOBE ALONG THE FRONT AND DIFFLUENCE IN THE RIGHT ENTRANCE REGION TO A 90KT 300MB JET. ALL THESE TOGETHER SUGGEST SCATTERED TO WIDESPREAD THUNDERSTORMS SATURDAY...WITH THE POTENTIAL FOR ISOLATED DAMAGING WIND GUSTS. THE LIMITING FACTOR MAY BE INCREASED CLOUD COVER FROM CONVECTIVE DEBRIS FRIDAY...BUT THIS IS STILL YET TO BE SEEN. WILL KEEP INHERITED LIKELY POP SATURDAY...WANING TO SCHC BY SUNDAY MORNING AS FRONT MOVES OFFSHORE. TEMPS SATURDAY WILL BE RIGHT AROUND CLIMO...90/70. DRIER AIR BEHIND THE FRONT COMBINED WITH SLIGHTLY INCREASED 500MB HEIGHTS WILL CAUSE A SIGNIFICANT DECREASE IN TSTM CHANCES SUN-TUE. STILL...WITH TEMPS AROUND 90 AND SLIGHTLY ENHANCED LAPSE RATES DUE TO BROAD EAST-COAST TROUGHING...ANY DAY COULD FEATURE ISOLATED DIURNAL CONVECTION. WILL KEEP POP BELOW MENTIONABLE SUN/MON BEFORE MOISTURE RETURN INCREASES WITH RETURN OF BERMUDA HIGH TUE/WED. TEMPS THROUGH THE WEEK WILL BE NEAR NORMAL FOR MID AUGUST. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... AS OF 18Z...SOME LIGHT SHOWERS WILL PERSISTS FOR THE FIRST COUPLE OF HOURS ALONG THE COAST. THEY SHOULD HAVE LITTLE AVIATION IMPACT. LOOK FOR VFR CONDITIONS THROUGH THE AFTERNOON HOURS...WITH ISOLATED SHOWERS POSSIBLE. LIGHT WINDS TONIGHT WITH SCATTERING SKIES. GIVEN THOSE CONDITIONS...ALONG WITH GOOD LOW LEVEL MOISTURE...EXPECT IFR FOG TO EMERGE AFTER 08Z. IT IS POSSIBLE IT COULD BECOME DENSE...BUT WILL STAY WITH IFR AT THIS TIME. THURSDAY...MORNING FOG SHOULD MIX OUT BY 13Z WITH VFR CONDITIONS EXPECTED. LIGHT NORTHWEST FLOW BEHIND THE DEEP MOISTURE EXITING THE REGION. EXTENDED OUTLOOK...CHANCE OF MORNING MVFR VSBYS IN BR WITH A CHANCE OF SHOWERS AND THUNDERSTORMS EACH DAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 6:00 PM WEDNESDAY...NO CHANGES TO COASTAL WATERS FORECAST WITH THE EVENING UPDATE. SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 3 PM WEDNESDAY...LIGHT WESTERLY FLOW THURSDAY MORNING WILL BACK TO A SOUTHERLY DIRECTION DURING THE DAY AND INCREASE INTO THE 10-15 KT RANGE. SOUTH TO SOUTHWEST FLOW WILL PREVAIL THURSDAY NIGHT AND LINGER AROUND 15 KT FRIDAY. SPEEDS COULD REACH 15-20 KT FRIDAY NIGHT AHEAD OF A COLD FRONT. THE SOUTH TO SOUTHWEST FETCH WILL ALLOW SEAS TO BUILD TO EXERCISE CAUTION LEVELS DURING THE PERIOD...AND WILL BE HIGHEST DURING FRIDAY NIGHT LONG TERM /SATURDAY THROUGH MONDAY/... AS OF 3 PM WEDNESDAY...SW FLOW THROUGH THE PERIOD...BUT WILL BE STRONGEST SATURDAY AS COLD FRONT APPROACHES FROM THE WEST. AS THIS FRONT WORKS TOWARDS THE COAST...PRESSURE GRADIENT TIGHTENS...AND WINDS WILL BE AROUND 15 KTS SATURDAY. GRADIENT WILL EASE AS FRONT MOVES TO THE WATERS AND DISSIPATES BY EARLY SUNDAY...BECOMING 10 KTS OR LESS SUNDAY AND MONDAY...STILL FROM THE SW. A WEAK SE SWELL WILL EXIST THROUGH THE EXTENDED...BUT SIGNIFICANT WAVE HEIGHTS WILL BE DRIVEN ALMOST EXCLUSIVELY BY THE WIND. 3-5 FT SEAS SATURDAY WILL DECREASE THROUGH SUNDAY...BECOMING 2-3 FT LATE SUNDAY AND MONDAY. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ NEAR TERM...15 SHORT TERM...SRP LONG TERM...JDW AVIATION...DL/HAWKINS
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
946 PM EDT THU AUG 9 2012 .SYNOPSIS... STRONG COLD FRONT FOR AUGUST PASSES LATE FRIDAY. HIGH PRESSURE BUILDS IN THIS WEEKEND WITH COOLER TEMPERATURES. && .NEAR TERM /THROUGH FRIDAY/... THE MID LEVEL 500 MB VORT MAX INDICATED BY RADAR STRUCTURE W OF PKB AT 01Z. RAP MDL HAS THE AXIS PASSING THRU NRN CNTRL WV AND ACRS NRN WV MTNS BY 05Z. SO RADAR COVERAGE INCREASING ACROSS CNTRL AND NRN WV COUNTIES AFTER 01Z...SHOULD SEE A DECREASING TREND 04Z TO 06Z. STILL HAVE INCREASING COVERAGE AGAIN IN MID OHIO VALLEY 09Z TO 12Z. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/... FRONTAL BOUNDARY WILL CROSS CWA FRI EVENING WITH SOME SHRA AND PERHAPS A RUMBLE OF THUNDER...AS UPR TROF SETTLES IN OVER LWR GREAT LAKES HEADING INTO WEEKEND. CARRIED LOW CHC POPS WITH THIS WITH DRYING AFTER MIDNIGHT AS DRY SLOT WORKS IN FROM W. LOOKS LIKE UPR COLD POOL ASSOCIATED CLDS WILL TEND TO STAY NORTH OF AREA AS COLUMN DRIES OUT FOR WEEKEND WITH JUST SOME DIURNALLY DRIVE STRATOCU BOTH DAYS. GUIDANCE HAS COME UP WITH MAXT NUMBERS FOR THIS WEEKEND. THIS MAKES SENSE WITH CORE OF UPR COLD POOL NEVER REALLY MAKING IT THIS FAR S WITH GENERALLY W TO WSW LLVL FLOW. THUS WILL BUMP UP NUMBERS A TICK OR TWO MAINLY OUTSIDE OF THE MTNS. WILL GO WITH COOLER NUMBERS FOR LOWS WITH GENERALLY LIGHT FLOW UNDER SFC HIGH...ALLOWING FOR BETTER RADIATIONAL COOLING. && .LONG TERM /MONDAY THROUGH THURSDAY/... EXTENDED WILL FEATURE UPR TROF REINFORCED EARLY NEXT WEEK AS GENERALLY NW FLOW ALOFT CONTINUES. OVERALL ATMOS REMAINS ON DRY SIDE...HOWEVER UPR DISTURBANCE MAY BRING A FEW MAINLY AFTN SHRA OR STORMS TUE OR WED. UPR TROF LOOKS TO PULL OUT TOWARD WEEKS END...REPLACED BY BUILDING HEIGHTS AND WARMER TEMPS. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... REMAINING OUT AHEAD OF THE SYNOPTIC SUPPORT AND COLD FRONT THROUGH MOST OF THIS TAF FORECAST PERIOD. DO NOT EXPECT WEAK LOW PRESSURE AND ASSOCIATED COLD FRONT TO PASS TRI STATE AROUND HTS UNTIL 21Z FRIDAY TO 00Z SATURDAY. OUT AHEAD OF THIS FEATURE...INDIVIDUAL BANDS OF CONVECTION WILL FORM IN THE MID LEVEL SUPPORT. EXPECTING WEAKENING CONVECTION IN SOUTHEAST OHIO DURING THE 03Z TO 06Z...WHILE CREEPING INTO NORTHWESTERN WEST VIRGINIA. MEANWHILE...SEPARATE AREA OF SHOWERS AND THUNDERSTORMS THURSDAY EVENING MAY HOLD TOGETHER AS IT MOVES UP THE MOUNTAINOUS COUNTIES OF WEST VIRGINIA FROM THE SSW. FIGURING A LULL IN COVERAGE 04Z TO 08Z...WITH CONVECTION INCREASING IN SOUTHEAST OHIO AGAIN BY THE PREDAWN HOURS. OVERNIGHT...CEILINGS 2 TO 4 THSD FT BKN AND VSBY NEAR 3 MILES IN CONVECTION OTHERWISE CEILINGS MOSTLY 6 TO 10 THSD FT BKN AND VSBY AOA 5 MILES. SOME LOCAL VALLEY FOG POSSIBLE IN DEEPER VALLEYS OF SOUTHERN WEST VIRGINIA AND IN THE MOUNTAINS MAY LOWER VSBY NEAR 3 MILES 06Z TO 12Z. LOW LEVEL FLOW INCREASING DURING THE DAY ON FRIDAY. EXPECTING CU AT 2 TO 4 THSD FT BKN AND VSBY OCCASIONALLY NEAR 3 MILES IN SHOWERS AND THUNDERSTORMS. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z SATURDAY... FORECAST CONFIDENCE: LOW. ALTERNATE SCENARIOS: TIMING THE INDIVIDUAL BANDS OF CONVECTION BY THE PREDAWN HOURS INTO THE DAY ON FRIDAY COULD BE FASTER AND SHORTER DURATIONS THAN INDICATED IN TAFS. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. DATE FRI 08/10/12 UTC 1HRLY 02 03 04 05 06 07 08 09 10 11 12 13 EDT 1HRLY 22 23 00 01 02 03 04 05 06 07 08 09 CRW CONSISTENCY H H H H H H H H H H H H HTS CONSISTENCY H H H H H H H H H L H H BKW CONSISTENCY H H H H H H H H H H H H EKN CONSISTENCY H H H H H H H M M M M M PKB CONSISTENCY H H H H H H H H H H H H CKB CONSISTENCY H H H H H H H H H H H H AFTER 00Z SATURDAY... IFR CONDITIONS POSSIBLE UNDER HEAVIEST SHOWERS/TSRA FRIDAY. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...30/26 NEAR TERM...KTB SHORT TERM...30 LONG TERM...30 AVIATION...KTB
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
818 PM EDT THU AUG 9 2012 .SYNOPSIS... STRONG COLD FRONT FOR AUGUST PASSES LATE FRIDAY. HIGH PRESSURE BUILDS IN THIS WEEKEND WITH COOLER TEMPERATURES. && .NEAR TERM /THROUGH FRIDAY/... AS EXPECTED...THE CONVECTION FORMED IN OHIO ALONG THE BOUNDARY AND IS SLOWLY CREEPING TOWARD THE MID OHIO VALLEY AND THE OHIO RIVER. YET...WE THOUGHT THE SOUTHERN RAIN WOULD SURVIVE INTO CENTRAL WV...BUT WEAKENED CONSIDERABLY IN SOUTHERN WV. YET...EVEN WHEN WE THOUGHT IT WAS FALLING APART...A NEW THUNDERSTORM FORMED NEAR OCEANA IN WYOMING COUNTY AT SUNSET. WAS MUCH SLOWER IN INCREASING POPS TONIGHT IN NORTH CENTRAL WV...FROM CKB INTO THE MOUNTAINS AROUND EKN. ONE VORT MAX ON THE RAP LIFTS NE THRU PKB AROUND 02Z INTO WRN PA BY 04Z. WILL TRY TO SPEED UP POPS INCREASING BEFORE DAWN IN SOUTHEAST OHIO AND THE OHIO RIVER. BUT HAVE LOW CONFIDENCE ON TIMING THE INITIAL BANDS ON FRIDAY. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/... FRONTAL BOUNDARY WILL CROSS CWA FRI EVENING WITH SOME SHRA AND PERHAPS A RUMBLE OF THUNDER...AS UPR TROF SETTLES IN OVER LWR GREAT LAKES HEADING INTO WEEKEND. CARRIED LOW CHC POPS WITH THIS WITH DRYING AFTER MIDNIGHT AS DRY SLOT WORKS IN FROM W. LOOKS LIKE UPR COLD POOL ASSOCIATED CLDS WILL TEND TO STAY NORTH OF AREA AS COLUMN DRIES OUT FOR WEEKEND WITH JUST SOME DIURNALLY DRIVE STRATOCU BOTH DAYS. GUIDANCE HAS COME UP WITH MAXT NUMBERS FOR THIS WEEKEND. THIS MAKES SENSE WITH CORE OF UPR COLD POOL NEVER REALLY MAKING IT THIS FAR S WITH GENERALLY W TO WSW LLVL FLOW. THUS WILL BUMP UP NUMBERS A TICK OR TWO MAINLY OUTSIDE OF THE MTNS. WILL GO WITH COOLER NUMBERS FOR LOWS WITH GENERALLY LIGHT FLOW UNDER SFC HIGH...ALLOWING FOR BETTER RADIATIONAL COOLING. && .LONG TERM /MONDAY THROUGH THURSDAY/... EXTENDED WILL FEATURE UPR TROF REINFORCED EARLY NEXT WEEK AS GENERALLY NW FLOW ALOFT CONTINUES. OVERALL ATMOS REMAINS ON DRY SIDE...HOWEVER UPR DISTURBANCE MAY BRING A FEW MAINLY AFTN SHRA OR STORMS TUE OR WED. UPR TROF LOOKS TO PULL OUT TOWARD WEEKS END...REPLACED BY BUILDING HEIGHTS AND WARMER TEMPS. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... REMAINING OUT AHEAD OF THE SYNOPTIC SUPPORT AND COLD FRONT THROUGH MOST OF THIS TAF FORECAST PERIOD. DO NOT EXPECT WEAK LOW PRESSURE AND ASSOCIATED COLD FRONT TO PASS TRI STATE AROUND HTS UNTIL 21Z FRIDAY TO 00Z SATURDAY. OUT AHEAD OF THIS FEATURE...INDIVIDUAL BANDS OF CONVECTION WILL FORM IN THE MID LEVEL SUPPORT. EXPECTING WEAKENING CONVECTION IN SOUTHEAST OHIO DURING THE 03Z TO 06Z...WHILE CREEPING INTO NORTHWESTERN WEST VIRGINIA. MEANWHILE...SEPARATE AREA OF SHOWERS AND THUNDERSTORMS THURSDAY EVENING MAY HOLD TOGETHER AS IT MOVES UP THE MOUNTAINOUS COUNTIES OF WEST VIRGINIA FROM THE SSW. FIGURING A LULL IN COVERAGE 04Z TO 08Z...WITH CONVECTION INCREASING IN SOUTHEAST OHIO AGAIN BY THE PREDAWN HOURS. OVERNIGHT...CEILINGS 2 TO 4 THSD FT BKN AND VSBY NEAR 3 MILES IN CONVECTION OTHERWISE CEILINGS MOSTLY 6 TO 10 THSD FT BKN AND VSBY AOA 5 MILES. SOME LOCAL VALLEY FOG POSSIBLE IN DEEPER VALLEYS OF SOUTHERN WEST VIRGINIA AND IN THE MOUNTAINS MAY LOWER VSBY NEAR 3 MILES 06Z TO 12Z. LOW LEVEL FLOW INCREASING DURING THE DAY ON FRIDAY. EXPECTING CU AT 2 TO 4 THSD FT BKN AND VSBY OCCASIONALLY NEAR 3 MILES IN SHOWERS AND THUNDERSTORMS. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z SATURDAY... FORECAST CONFIDENCE: LOW. ALTERNATE SCENARIOS: TIMING THE INDIVIDUAL BANDS OF CONVECTION BY THE PREDAWN HOURS INTO THE DAY ON FRIDAY COULD BE FASTER AND SHORTER DURATIONS THAN INDICATED IN TAFS. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. DATE FRI 08/10/12 UTC 1HRLY 00 01 02 03 04 05 06 07 08 09 10 11 EDT 1HRLY 20 21 22 23 00 01 02 03 04 05 06 07 CRW CONSISTENCY H H H H H H H H H H H H HTS CONSISTENCY H H H H H H H H H H H L BKW CONSISTENCY M H H H H H H H H H H H EKN CONSISTENCY H H H H H H H H H M M M PKB CONSISTENCY M H H H H H H H H H H H CKB CONSISTENCY H H H H H H H H H H H H AFTER 00Z SATURDAY... IFR CONDITIONS POSSIBLE UNDER HEAVIEST SHOWERS/TSRA FRIDAY. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...30/26 NEAR TERM...KTB SHORT TERM...30 LONG TERM...30 AVIATION...KTB
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
431 PM EDT WED AUG 8 2012 .SYNOPSIS... A WEAK COLD FRONT WILL REMAIN NEARLY STATIONARY ALONG THE OHIO RIVER TONIGHT INTO THURSDAY. A STRONGER COLD FRONT AHEAD OF AN ENERGETIC UPPER LEVEL LOW WILL BRING A ROUND OF SHOWERS AND THUNDERSTORMS TO THE OHIO VALLEY ON THURSDAY NIGHT AND FRIDAY. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... A WEAK COLD FRONT HAD DROPPED SOUTH INTO NORTHERN OHIO AND INDIANA LATE THIS AFTERNOON. THIS AFTERNOON...WIDELY SCATTERED TO SCATTERED SHOWERS AND THUNDERSTORMS HAD DEVELOPED ALONG AND AHEAD OF THE COLD FRONT DUE TO WEAK LOW LEVEL FORCING AND HOT AFTERNOON TEMPERATURES. THIS FRONT WILL CONTINUE TO DROP SOUTH TONIGHT AND BECOME NEARLY STATIONARY NEAR THE OHIO RIVER. THE SHOWER AND THUNDERSTORM ACTIVITY WILL DECREASE THROUGH THE LATE EVENING HOURS. ANOTHER CHANCE OF SHOWERS/THUNDERSTORMS WILL OCCUR IN THE EARLY MORNING HOURS WITH AN UPPER LEVEL SYSTEM. WITH HIGH INSTABILITY ACROSS THE REGION THROUGH THIS EVENING...CAN NOT RULE OUT AN ISOLATED SEVERE THUNDERSTORM. DAMAGING WINDS AND LARGE HAIL WOULD BE THE MAIN THREATS. THE LOWS TONIGHT WILL BE WARMER THAN WEDNESDAY NIGHT WITH LOWS IN THE MID 60S TO AROUND 70. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/... THE WEAK COLD FRONT WILL LAY OUT AS A BOUNDARY ON THURSDAY AND ANOTHER MID LEVEL SHORTWAVE WILL INTERACT WITH IT. THIS WILL BRING A BETTER CHANCE OF THUNDERSTORMS ACROSS THE FORECAST AREA. WILL ALSO SEE A CHANCE OF SEVERE WEATHER WITH THE MAIN THREAT BEING DAMAGING WINDS. LOW PRESSURE WILL RIDE NE ALONG THE BOUNDARY THURSDAY NIGHT IN RESPONSE TO AN UPPER LOW STRENGTHENING OVER THE WESTERN GREAT LAKES AND CROSSING THE NORTHERN OHIO VALLEY BY EARLY FRI. MODELS HANDLE THE TRACK OF THE LOW A LITTLE DIFFERENTLY WHICH WILL IMPACT WHERE GREATEST PRECIPITATION OCCURRS. THE BEST COVERAGE OF SHOWERS/THUNDERSTORMS WILL BE LATE THURSDAY INTO FRIDAY AS THE LOW APPROACHES AND MOVES THROUGH THE OHIO VALLEY REGION. WITH AN INCREASE IN CLOUDS AND PRECIPITATION THURSDAY...THE HIGH TEMEPRATURES WILL BE COOLER THAN TODAY. MOST AREAS WILL SEE HIGHS IN THE 80S EXCEPT AROUND 90 IN THE FAR SE. THE LOWS THURSDAY NIGHT WILL BE IN THE 60S. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... CLOSED UPPER LOW PROGGED TO BE OVER LOWER MICHIGAN AT 12Z FRIDAY WITH SURFACE LOW POSITIONED OVER LAKE ERIE. THIS SYSTEM WILL GRADUALLY PUSH FURTHER NORTHEASTWARD INTO CANADA THROUGH THE FIRST PART OF THE WEEKEND...LEAVING MAINLY DRY AND COOLER CONDITIONS IN ITS WAKE. WENT ON THE COOL SIDE OF GUIDANCE FOR FRIDAY AS CLOUDS... PRECIPITATION...AND NORTHERLY FLOW BEHIND A FRONTAL BOUNDARY WILL KEEP TEMPERATURES DOWN. FORECASTED HIGHS FOR FRIDAY RIGHT NOW ARE ABOUT 10 DEGREES BELOW NORMAL. BOTH THE 00Z AND 12Z ECMWF RUNS HAVE BEEN A LITTLE QUICKER TO PUSH THE SYSTEM OUT OF THE AREA THAN THE LATEST NAM/GFS...SO DECIDED TO KEEP JUST SLIGHT POPS INTO SATURDAY FOR THE FAR NORTHEASTERN CWA. EXPECT A GRADUAL CLEARING SATURDAY AFTERNOON INTO THE OVERNIGHT AS THE LOW PUSHES AWAY. LOWS SATURDAY NIGHT WILL BE COOL AS HIGH PRESSURE BUILDS INTO THE REGION. WINDS WILL BECOME MORE SOUTHERLY BY SUNDAY THE HIGH DRIFTS EAST OF THE REGION. THIS WILL BE THE START OF A WARMING TREND THAT WILL CONTINUE THROUGH THE FIRST PART OF NEXT WEEK WITH TEMPERATURES BACK IN THE 80S. ONLY OTHER FEATURES OF CONCERN FOR THE EXTENDED PERIOD WILL ARRIVE MONDAY INTO MONDAY NIGHT AS THE GFS BRINGS A DECENT SHORTWAVE AND SURFACE LOW THROUGH THE REGION. NEITHER FEATURE HAS BEEN QUITE AS DEVELOPED IN THE PAST TWO ECMWF RUNS AND THUS THE ECMWF HAS BEEN TRENDING DRY. WENT AHEAD AND INTRODUCED SLIGHT POPS FOR THIS PERIOD AS THE PAST FEW GFS RUNS HAVE BEEN CONSISTENT AND THE FEATURES ARE AT LEAST EVIDENT IN THE ECMWF...BUT CONFIDENCE IN PRECIP IS NOT VERY HIGH AT THIS TIME. && .AVIATION /20Z WEDNESDAY THROUGH MONDAY/... CU FIELD IS TRYING TO FILL IN ACROSS THE AREA EARLY THIS AFTERNOON AS WE CONTINUE TO WARM UP AND DESTABILIZE. ML CAPES ARE NOW INTO THE 1500 TO 2000 J/KG RANGE ACROSS MUCH OF THE REGION. AS THE COLD FRONT SAGS SLOWLY SOUTH ACROSS THE REGION THROUGH THIS EVENING...A FEW THUNDERSTORMS MAY POP UP GIVEN THE INSTABILITY AND WEAK LOW LEVEL FORCING. MEANWHILE...REMNANTS FROM EARLIER CONVECTION ARE CONTINUING TO PROGRESS ACROSS ILLINOIS TOWARD WESTERN INDIANA. THE LAST FEW RUNS OF THE RAP HAVE BEEN TRYING TO PIVOT A WEAKENING LINE OF SHOWERS ASSOCIATED WITH THIS UP ACROSS AT LEAST OUR WESTERN AREAS THROUGH EARLY EVENING. GIVEN THE UNCERTAINTY...THINK THE BEST WAY TO COVER THE CHANCE RIGHT NOW IS JUST WITH A VCSH. ANOTHER WEAK MID LEVEL SHORT WAVE WILL THEN PUSH TOWARD THE AREA LATE TONIGHT INTO THURSDAY MORNING. EXPECT THE BEST CHANCE FOR ANY PCPN ASSOCIATED WITH THIS TO BE ACROSS OUR NORTH AND WILL AGAIN COVER WITH A VCSH. A BETTER CHANCE OF SHOWERS AND THUNDERSTORMS WILL THEN DEVELOP OFF TO OUR WEST THROUGH THE AFTERNOON HOURS...POSSIBLY AFFECTING CVG TOWARD THE END OF THEIR TAF PERIOD. .OUTLOOK...THUNDERSTORMS ARE POSSIBLE INTO FRIDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...PARKER NEAR TERM...PARKER SHORT TERM...PARKER LONG TERM...KURZ AVIATION...JGL
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
154 PM EDT WED AUG 8 2012 .SYNOPSIS... A WEAK COLD FRONT WILL CROSS THE REGION TODAY. THIS FRONT WILL REMAIN NEARLY STATIONARY ALONG THE OHIO RIVER TONIGHT INTO THURSDAY. A STRONGER COLD FRONT AHEAD OF AN ENERGETIC UPPER LEVEL LOW WILL BRING A ROUND OF SHOWERS AND THUNDERSTORMS TO THE OHIO VALLEY ON THURSDAY NIGHT AND FRIDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... LOOKS LIKE MAYBE A FEW AC UP ACROSS OUR NORTH BUT FOR THE MOST PART...SKIES ARE MOSTLY CLEAR THIS MORNING. A WEAK COLD FRONT CURRENTLY ACROSS FAR NORTHERN INDIANA AND OHIO...WILL SAG SOUTH INTO OUR AREA THROUGH THIS AFTERNOON. AHEAD OF THE FRONT...WE SHOULD SEE A DECENT WARM UP THROUGH THIS AFTERNOON. TEMPS ARE CURRENTLY RUNNING SEVERAL DEGREES AHEAD OF YESTERDAY AND THE 12Z ILN SOUNDING IS 19 DEGREES AT 850 MB...WHICH IS 3 DEGREES WARMER THAN TUESDAY MORNING. AS A RESULT...EXPECT TEMPERATURES 4 TO MAYBE EVEN 5 DEGREES WARMER THAN WHAT SAW YESTERDAY AFTERNOON...ESPECIALLY ACROSS SOUTHERN PORTIONS OF OUR AREA WHERE BEST LOW LEVEL WAA SHOULD EXIST AHEAD OF THE FRONT. WILL GENERALLY HAVE HIGHS IN THE LOW TO MID 90S. CVG DID GET TO 95 DEGREES YESTERDAY...SO A FEW UPPER 90S ARE NOT OUT OF THE QUESTION ACROSS OUR SOUTHWEST. THE RECORD FOR CVG IS 100 DEGREES AND CMH IS 96...SO WE MAY NOT BE TOO FAR OFF FROM THOSE NUMBERS. MEANWHILE AS WE DESTABILIZE THROUGH THIS AFTERNOON...TOUGH TO RULE OUT A FEW THUNDERSTORMS GIVEN WEAK LOW LEVEL FORCING ALONG THE FRONT. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/... THE WEAK COLD FRONT WILL LAY OUT AS A BOUNDARY ON THURSDAY AND ANOTHER MID LEVEL SHORTWAVE WILL INTERACT WITH IT AND STAND A BETTER CHANCE OF POPPING SOME THUNDERSTORMS OVER THE AREA. THE BOUNDARY WILL SEE LOW PRESSURE RIDE NORTHEAST ALONG IT THURSDAY NIGHT IN RESPONSE TO AN UPPER LOW STRENGTHENING OVER THE WESTERN GREAT LAKES AND CROSSING THE NORTHERN OHIO VALLEY BY EARLY FRIDAY. THE SHOWERS AND THUNDERSTORMS THAT DEVELOP THURSDAY NIGHT IN RESPONSE TO THESE FEATURES WILL BECOME MORE AND MORE LIKELY AS TIME PROGRESSES. TEMPERATURES ON FRIDAY WILL BE MARKEDLY COOLER...UPPER 60S TO LOWER 70S IN A COLD ADVECTION PATTERN AND NOTABLY WETTER IN THE POST-FRONTAL WRAP AROUND MOISTURE. SIGNIFICANTLY COOLER AIR WILL BE OVER THE REGION THIS WEEKEND AS A CUTOFF LOW PROVIDES FOR CLOUDY SKIES AND A CONTINUED COLD PUSH ON NORTHERLY WINDS. && .LONG TERM /SATURDAY THROUGH TUESDAY/... FOR SATURDAY INTO SATURDAY NIGHT...A QUICKER UPR LVL LOW MOTION TO THE NE WAS USED BUT MAY END UP BEING SLOWER THAN CURRENTLY FORECAST DUE TO RECENT MODEL GUIDANCE. HAVE A CHANCE OF SHOWERS DIMINISHING WEST TO EAST THROUGH THIS PERIOD ALONG WITH GRADUAL CLEARING SATURDAY INTO SATURDAY NIGHT. TEMPERATURES ON SATURDAY WILL BE CLOUD DEPENDENT AND HAVE GONE WITH HIGHS IN THE MID TO UPPER 70S. LOWS SATURDAY NIGHT WILL BE COOL AS SURFACE HIGH PRESSURE BUILDS INTO THE REGION. FOR THE REMAINDER OF THE EXTENDED...SUNDAY THROUGH TUESDAY...THE GREAT LAKES AND OHIO VALLEY AREA WILL BE UNDER A NORTHWEST FLOW PATTERN ALOFT. THERE ARE INDICATIONS THAT A FEW WEAK DISTURBANCES WILL RIPPLE SE WITHIN THIS FLOW...BRINGING A SMALL THREAT FOR PCPN. GIVEN THAT THEY APPEAR WEAK ATTM AND TIMING IS DIFFICULT AT BEST AT THIS JUNCTURE...HAVE MAINTAINED A DRY FORECAST ALONG WITH MODIFYING TEMPERATURES AS HEIGHTS AND TEMPERATURES ALOFT RISE THROUGH THE PERIOD. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... CU FIELD IS TRYING TO FILL IN ACROSS THE AREA EARLY THIS AFTERNOON AS WE CONTINUE TO WARM UP AND DESTABILIZE. ML CAPES ARE NOW INTO THE 1500 TO 2000 J/KG RANGE ACROSS MUCH OF THE REGION. AS THE COLD FRONT SAGS SLOWLY SOUTH ACROSS THE REGION THROUGH THIS EVENING...A FEW THUNDERSTORMS MAY POP UP GIVEN THE INSTABILITY AND WEAK LOW LEVEL FORCING. MEANWHILE...REMNANTS FROM EARLIER CONVECTION ARE CONTINUING TO PROGRESS ACROSS ILLINOIS TOWARD WESTERN INDIANA. THE LAST FEW RUNS OF THE RAP HAVE BEEN TRYING TO PIVOT A WEAKENING LINE OF SHOWERS ASSOCIATED WITH THIS UP ACROSS AT LEAST OUR WESTERN AREAS THROUGH EARLY EVENING. GIVEN THE UNCERTAINTY...THINK THE BEST WAY TO COVER THE CHANCE RIGHT NOW IS JUST WITH A VCSH. ANOTHER WEAK MID LEVEL SHORT WAVE WILL THEN PUSH TOWARD THE AREA LATE TONIGHT INTO THURSDAY MORNING. EXPECT THE BEST CHANCE FOR ANY PCPN ASSOCIATED WITH THIS TO BE ACROSS OUR NORTH AND WILL AGAIN COVER WITH A VCSH. A BETTER CHANCE OF SHOWERS AND THUNDERSTORMS WILL THEN DEVELOP OFF TO OUR WEST THROUGH THE AFTERNOON HOURS...POSSIBLY AFFECTING CVG TOWARD THE END OF THEIR TAF PERIOD. .OUTLOOK...THUNDERSTORMS ARE POSSIBLE INTO FRIDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...FRANKS NEAR TERM...JGL SHORT TERM...FRANKS LONG TERM...HICKMAN AVIATION...JGL
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
120 PM EDT WED AUG 8 2012 .SYNOPSIS... A WEAK COLD FRONT JUST NORTH OF LAKE ERIE WILL MOVE SOUTHEAST ACROSS THE LOCAL AREA TODAY AND THEN STALL NEAR THE OHIO RIVER. LOW PRESSURE WILL MOVE UP THE OHIO VALLEY THURSDAY AND FRIDAY. HIGH PRESSURE WILL SLOWLY BUILD OVER THE REGION FROM THE WEST OVER THE WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... COLD FRONT FROM JUST NORTH OF BUF TO JUST SOUTH OF TOL. FORECAST LOOKS REASONABLE. MADE MINOR ADJUSTMENTS TO THE TIMING OF THE CLOUD COVER FOR UPDATE. PREVIOUS...THE COLD FRONT IS ON TRACK TO MOVE SE ACROSS THE AREA TODAY. SOME SHOWERS AND EVEN SOME LIGHTNING OCCURRED EARLIER IN THE NIGHT ALONG THE FRONT ACROSS LOWER MICHIGAN. LATEST HRRR AND CONVECTIVE SREF CONTINUE TO SUGGEST THAT ISOLATED TO SCATTERED SHOWERS AND STORMS WILL DEVELOP ALONG THE FRONT LATER TODAY. BEST CHANCES FOR THIS WILL BE IN THE EAST THIS AFTERNOON. HAVE GONE WITH A 20 TO 30 POP MOST AREAS. CLOUDS WILL COME AND GO TODAY BUT BY LATE AFTERNOON SKIES SHOULD BE MAINLY PARTLY CLOUDY. HIGH TEMPS WILL BE A DEGREE OR TWO COOLER THAN TUESDAY. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/... ACTIVE WEATHER IS EXPECTED DURING THE PERIOD AS AN UPPER LOW GETS SET UP OVER THE EASTERN CONUS. THE MODELS NOW ARE FAIRLY SIMILAR WITH THE MAIN FEATURES. LOW PRESSURE IS EXPECTED TO MOVE UP THE OHIO VALLEY TONIGHT AND FRIDAY WITH THE LOW EVENTUALLY CROSSING WESTERN PA. MODELS SHOWING GOOD ISENTROPIC LIFT WITH PWAT VALUES EVENTUALLY REACHING 1.75 INCHES. INSTABILITY WILL INCREASE TONIGHT AND THURSDAY AS DEWPOINTS SURGE INTO THE UPPER 60S. A FEW STRONG TO SEVERE STORMS ARE LIKELY LATE THURSDAY AS THE LOW PASSES. SHEAR WILL BE ENHANCED ALONG THE FRONT STRETCHING NE FROM THE LOW. THAT IS LIKELY WHERE ANY SEVERE WEATHER WILL OCCUR. WRAP AROUND MOISTURE BEHIND THE LOW WILL KEEP SHOWERS GOING THROUGH MIDDAY SATURDAY ALL AREAS AND IN THE EAST ON SATURDAY NIGHT. 850 MB TEMPS DIP TO PLUS 8 OR 10 SATURDAY DEPENDING ON WHICH MODEL YOU BELIEVE. EITHER WAY COLD AIR ADVECTION CLOUDS AND SHOWERS WILL BE LIKELY TO THE EAST OF KCLE. EXPECT MUCH OF THE AREA TO SEE AN INCH OR MORE OR RAIN THURSDAY THROUGH FRIDAY. TEMPS DURING THE PERIOD WILL BE BELOW NORMAL FOR A CHANGE. && .LONG TERM /SUNDAY THROUGH TUESDAY/... MODELS CONTINUING TO HANDLE STRONG UPPER TROUGH OVER THE AREA WELL WITH GFS AND ECMWF MOVING IT OFF TO THE EAST ON SUNDAY WITH SFC HIGH PRESSURE BUILDING INTO THE AREA. GOING INTO EARLY NEXT WEEK MADE LITTLE CHANGES OVERALL TO THE FORECAST WITH 00Z ECMWF SHOWING BROAD UPPER TROUGH MOVING ACROSS THE AREA WHILE GFS ALSO BRINGING UPPER TROUGH OVER THE AREA BUT A BIT STRONGER WITH SFC LOW PRESSURE DEVELOPING OVER THE MID MISSISSIPPI VALLEY. FOR NOW WILL CONTINUE TO LEAN TOWARD THE ECMWF WITH MAINLY DRY CONDITIONS...BUT HAVE CONTINUE WITH MORE CLOUDINESS ACROSS THE AREA DURING THIS TIME. WITH NO STRONG TEMP ADVECTION MODERATED TEMPS FOR SUNDAY WITH THE TROUGH DEPARTING BUT OTHERWISE KEPT THEM NEAR NORMAL FOR EARLY NEXT WEEK. && .AVIATION /18Z WEDNESDAY THROUGH SUNDAY/... A WEAK COLD FRONT WILL BECOME STATIONARY OVER THE CENTRAL PORTION OF OHIO THIS EVENING. THIS BOUNDARY MAY CAUSE ENOUGH LOW LEVEL CONVERGENCE TO CAUSE A COUPLE THUNDERSTORMS TO DEVELOP OVER NE OHIO INTO NW PA. ONLY HAVE MENTIONED VICINITY THUNDER FOR THE KYNG TAF AT THIS TIME. HOWEVER WILL WATCH INLAND LOCATIONS FURTHER WEST THROUGH THE AFTERNOON. UNCERTAINTY AS WE APPROACH SUNRISE IS THE AMOUNT OF MVFR FOG THAT CAN DEVELOP WITH THE OVERALL INCREASE IN LIFT AS THE UPPER LEVEL TROUGH ARRIVES. AT THIS POINT DID NOT INTRODUCE ANY INTO THE TAF SITES BUT IF IT CAN OCCUR IT MAY BE ACROSS THE WESTERN TAF SITES. BELIEVE THERE WILL ALSO BE SOME SHOWERS THAT DRIFT INTO THE WEST ABOUT THE SAME TIME AS THE MVFR VISIBILITIES. SO FAR HAVE ONLY INTRODUCED A VICINITY SHOWER WITH UNCERTAINTY ON HOW FAST IT WILL MOVE INTO NW OHIO. THERE WILL EVENTUALLY BE A THREAT OF THUNDERSTORMS AS WE HEAT THE SURFACE INTO THE EARLY AFTERNOON. .OUTLOOK...PERIODS OF NON VFR POSSIBLE THURSDAY AND FRIDAY. NON VFR POSSIBLE SATURDAY ACROSS NE OHIO INTO NW PA. && .MARINE... A WEAK COLD FRONT WILL MOVE ACROSS THE LAKE TODAY BUT SHOULD CAUSE ANY SIGNIFICANT WEATHER OTHER THAN THE WIND SHIFT FROM SOUTHWEST TO NORTH TONIGHT. THE SIGNIFICANT WEATHER ISSUE FOR THE LAKE WILL BEGIN THURSDAY AS A STRONG UPPER TROUGH MOVES TOWARD THE LAKE AND SFC LOW PRESSURE INTENSIFIES OVER THE OHIO VALLEY...THEN MOVES TO THE NORTHEAST FRIDAY. NORTHEAST FLOW WILL INCREASE THROUGH THURSDAY WITH WINDS RANGING 20 KNOTS OR GREATER BY THURSDAY NIGHT AND CONTINUING THROUGH FRIDAY NIGHT. WINDS WILL SLOWLY DIMINISH THROUGH SATURDAY. HIGH PRESSURE WILL BUILD OVER THE LAKE ON SUNDAY. SMALL CRAFT ADVISORY CONDITIONS APPEAR LIKELY BEGINNING THURSDAY NIGHT AND CONTINUING THROUGH AT LEAST SATURDAY MORNING. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...NONE. PA...NONE. MARINE...NONE. && $$ SYNOPSIS...KUBINA NEAR TERM...DJB/KUBINA SHORT TERM...KUBINA LONG TERM...ABE AVIATION...MULLEN MARINE...ABE
AREA FORECAST DISCUSSION...UPDATED
NWS CLEVELAND OH
909 AM EDT WED AUG 8 2012 .SYNOPSIS... A WEAK COLD FRONT JUST NORTH OF LAKE ERIE WILL MOVE SOUTHEAST ACROSS THE LOCAL AREA TODAY AND THEN STALL NEAR THE OHIO RIVER. LOW PRESSURE WILL MOVE UP THE OHIO VALLEY THURSDAY AND FRIDAY. HIGH PRESSURE WILL SLOWLY BUILD OVER THE REGION FROM THE WEST OVER THE WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... COLD FRONT FROM JUST NORTH OF BUF TO JUST SOUTH OF TOL. FORECAST LOOKS REASONABLE. MADE MINOR ADJUSTMENTS TO THE TIMING OF THE CLOUD COVER FOR UPDATE. PREVIOUS...THE COLD FRONT IS ON TRACK TO MOVE SE ACROSS THE AREA TODAY. SOME SHOWERS AND EVEN SOME LIGHTNING OCCURRED EARLIER IN THE NIGHT ALONG THE FRONT ACROSS LOWER MICHIGAN. LATEST HRRR AND CONVECTIVE SREF CONTINUE TO SUGGEST THAT ISOLATED TO SCATTERED SHOWERS AND STORMS WILL DEVELOP ALONG THE FRONT LATER TODAY. BEST CHANCES FOR THIS WILL BE IN THE EAST THIS AFTERNOON. HAVE GONE WITH A 20 TO 30 POP MOST AREAS. CLOUDS WILL COME AND GO TODAY BUT BY LATE AFTERNOON SKIES SHOULD BE MAINLY PARTLY CLOUDY. HIGH TEMPS WILL BE A DEGREE OR TWO COOLER THAN TUESDAY. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/... ACTIVE WEATHER IS EXPECTED DURING THE PERIOD AS AN UPPER LOW GETS SET UP OVER THE EASTERN CONUS. THE MODELS NOW ARE FAIRLY SIMILAR WITH THE MAIN FEATURES. LOW PRESSURE IS EXPECTED TO MOVE UP THE OHIO VALLEY TONIGHT AND FRIDAY WITH THE LOW EVENTUALLY CROSSING WESTERN PA. MODELS SHOWING GOOD ISENTROPIC LIFT WITH PWAT VALUES EVENTUALLY REACHING 1.75 INCHES. INSTABILITY WILL INCREASE TONIGHT AND THURSDAY AS DEWPOINTS SURGE INTO THE UPPER 60S. A FEW STRONG TO SEVERE STORMS ARE LIKELY LATE THURSDAY AS THE LOW PASSES. SHEAR WILL BE ENHANCED ALONG THE FRONT STRETCHING NE FROM THE LOW. THAT IS LIKELY WHERE ANY SEVERE WEATHER WILL OCCUR. WRAP AROUND MOISTURE BEHIND THE LOW WILL KEEP SHOWERS GOING THROUGH MIDDAY SATURDAY ALL AREAS AND IN THE EAST ON SATURDAY NIGHT. 850 MB TEMPS DIP TO PLUS 8 OR 10 SATURDAY DEPENDING ON WHICH MODEL YOU BELIEVE. EITHER WAY COLD AIR ADVECTION CLOUDS AND SHOWERS WILL BE LIKELY TO THE EAST OF KCLE. EXPECT MUCH OF THE AREA TO SEE AN INCH OR MORE OR RAIN THURSDAY THROUGH FRIDAY. TEMPS DURING THE PERIOD WILL BE BELOW NORMAL FOR A CHANGE. && .LONG TERM /SUNDAY THROUGH TUESDAY/... MODELS CONTINUING TO HANDLE STRONG UPPER TROUGH OVER THE AREA WELL WITH GFS AND ECMWF MOVING IT OFF TO THE EAST ON SUNDAY WITH SFC HIGH PRESSURE BUILDING INTO THE AREA. GOING INTO EARLY NEXT WEEK MADE LITTLE CHANGES OVERALL TO THE FORECAST WITH 00Z ECMWF SHOWING BROAD UPPER TROUGH MOVING ACROSS THE AREA WHILE GFS ALSO BRINGING UPPER TROUGH OVER THE AREA BUT A BIT STRONGER WITH SFC LOW PRESSURE DEVELOPING OVER THE MID MISSISSIPPI VALLEY. FOR NOW WILL CONTINUE TO LEAN TOWARD THE ECMWF WITH MAINLY DRY CONDITIONS...BUT HAVE CONTINUE WITH MORE CLOUDINESS ACROSS THE AREA DURING THIS TIME. WITH NO STRONG TEMP ADVECTION MODERATED TEMPS FOR SUNDAY WITH THE TROUGH DEPARTING BUT OTHERWISE KEPT THEM NEAR NORMAL FOR EARLY NEXT WEEK. && .AVIATION /13Z WEDNESDAY THROUGH SUNDAY/... A WEAK COLD FRONT FROM LAKE ERIE ACROSS SRN MI WILL CONTINUE MOVING SOUTH OVER NRN OH TODAY. SATELLITE SHOWING SOME CLOUDS ALONG THE FRONT SO WENT WITH SCT-BKN 060-080 ACROSS SITES. MODELS SHOWING THE POSSIBILITY OF SOME SHRA DEVELOPING ALONG THE FRONT LATER THIS MORNING AND INTO THE AFTERNOON...BUT FOR LOCATIONS SUCH AS TOL-CLE THINKING THAT ANY DEVELOPMENT WOULD OCCUR SOUTH OF THOSE SITES. OVERALL GIVEN LOW PROBABILITIES DID MENTION SOME VCSH AT SEVERAL SITES INCLUDING FDY-MFD-CAK-YNG. TOO LOW CONF AT ERI TO INCLUDE VCSH. ALSO...GIVEN SUCH ISOLATED PROBABILITIES WILL HOLD OFF ON THUNDER AT SITES. SOUTHWEST WINDS SHIFTING W THEN NORTHERLY THROUGH TODAY WITH FROPA. HIGH CLOUDS WILL QUICKLY BUILD IN FROM THE WEST LATE TODAY AND THROUGH TONIGHT WITH NEXT WEATHER SYSTEM. CIGS LOWER TOWARD 10K FT LATER TONIGHT WITH MAINLY NE FLOW DEVELOPING. POSSIBLE MVFR VIS DEVELOPING BUT LATE IN PERIOD SO WILL LET NEXT SHIFT EVALUATE PROBABILITY OF THAT. .OUTLOOK...PERIODS OF NON VFR POSSIBLE THURSDAY AND FRIDAY ACROSS ALL SITES. NON VFR POSSIBLE SATURDAY ACROSS EASTERN SITES. && .MARINE... A WEAK COLD FRONT WILL MOVE ACROSS THE LAKE TODAY BUT SHOULD CAUSE ANY SIGNIFICANT WEATHER OTHER THAN THE WIND SHIFT FROM SOUTHWEST TO NORTH TONIGHT. THE SIGNIFICANT WEATHER ISSUE FOR THE LAKE WILL BEGIN THURSDAY AS A STRONG UPPER TROUGH MOVES TOWARD THE LAKE AND SFC LOW PRESSURE INTENSIFIES OVER THE OHIO VALLEY...THEN MOVES TO THE NORTHEAST FRIDAY. NORTHEAST FLOW WILL INCREASE THROUGH THURSDAY WITH WINDS RANGING 20 KNOTS OR GREATER BY THURSDAY NIGHT AND CONTINUING THROUGH FRIDAY NIGHT. WINDS WILL SLOWLY DIMINISH THROUGH SATURDAY. HIGH PRESSURE WILL BUILD OVER THE LAKE ON SUNDAY. SMALL CRAFT ADVISORY CONDITIONS APPEAR LIKELY BEGINNING THURSDAY NIGHT AND CONTINUING THROUGH AT LEAST SATURDAY MORNING. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...NONE. PA...NONE. MARINE...NONE. && $$ SYNOPSIS...KUBINA NEAR TERM...DJB/KUBINA SHORT TERM...KUBINA LONG TERM...ABE AVIATION...ABE MARINE...ABE
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
729 AM EDT WED AUG 8 2012 .SYNOPSIS... A WEAK COLD FRONT JUST NORTH OF LAKE ERIE WILL MOVE SOUTHEAST ACROSS THE LOCAL AREA TODAY AND THEN STALL NEAR THE OHIO RIVER. LOW PRESSURE WILL MOVE UP THE OHIO VALLEY THURSDAY AND FRIDAY. HIGH PRESSURE WILL SLOWLY BUILD OVER THE REGION FROM THE WEST OVER THE WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... UPDATE ALREADY OUT. THE LATEST HRRR NOW SHOWING SCATTERED STORMS DEVELOPING ALONG THE COLD FRONT THIS AFTERNOON. HAVE RAISED PRECIP CHANCES SLIGHTLY OVER THE SE 1/3 OF THE AREA. MINOR ADJUSTMENTS TO THE SKY COVER AS WELL. PREVIOUS...THE COLD FRONT IS ON TRACK TO MOVE SE ACROSS THE AREA TODAY. SOME SHOWERS AND EVEN SOME LIGHTNING OCCURRED EARLIER IN THE NIGHT ALONG THE FRONT ACROSS LOWER MICHIGAN. LATEST HRRR AND CONVECTIVE SREF CONTINUE TO SUGGEST THAT ISOLATED TO SCATTERED SHOWERS AND STORMS WILL DEVELOP ALONG THE FRONT LATER TODAY. BEST CHANCES FOR THIS WILL BE IN THE EAST THIS AFTERNOON. HAVE GONE WITH A 20 TO 30 POP MOST AREAS. CLOUDS WILL COME AND GO TODAY BUT BY LATE AFTERNOON SKIES SHOULD BE MAINLY PARTLY CLOUDY. HIGH TEMPS WILL BE A DEGREE OR TWO COOLER THAN TUESDAY. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/... ACTIVE WEATHER IS EXPECTED DURING THE PERIOD AS AN UPPER LOW GETS SET UP OVER THE EASTERN CONUS. THE MODELS NOW ARE FAIRLY SIMILAR WITH THE MAIN FEATURES. LOW PRESSURE IS EXPECTED TO MOVE UP THE OHIO VALLEY TONIGHT AND FRIDAY WITH THE LOW EVENTUALLY CROSSING WESTERN PA. MODELS SHOWING GOOD ISENTROPIC LIFT WITH PWAT VALUES EVENTUALLY REACHING 1.75 INCHES. INSTABILITY WILL INCREASE TONIGHT AND THURSDAY AS DEWPOINTS SURGE INTO THE UPPER 60S. A FEW STRONG TO SEVERE STORMS ARE LIKELY LATE THURSDAY AS THE LOW PASSES. SHEAR WILL BE ENHANCED ALONG THE FRONT STRETCHING NE FROM THE LOW. THAT IS LIKELY WHERE ANY SEVERE WEATHER WILL OCCUR. WRAP AROUND MOISTURE BEHIND THE LOW WILL KEEP SHOWERS GOING THROUGH MIDDAY SATURDAY ALL AREAS AND IN THE EAST ON SATURDAY NIGHT. 850 MB TEMPS DIP TO PLUS 8 OR 10 SATURDAY DEPENDING ON WHICH MODEL YOU BELIEVE. EITHER WAY COLD AIR ADVECTION CLOUDS AND SHOWERS WILL BE LIKELY TO THE EAST OF KCLE. EXPECT MUCH OF THE AREA TO SEE AN INCH OR MORE OR RAIN THURSDAY THROUGH FRIDAY. TEMPS DURING THE PERIOD WILL BE BELOW NORMAL FOR A CHANGE. && .LONG TERM /SUNDAY THROUGH TUESDAY/... MODELS CONTINUING TO HANDLE STRONG UPPER TROUGH OVER THE AREA WELL WITH GFS AND ECMWF MOVING IT OFF TO THE EAST ON SUNDAY WITH SFC HIGH PRESSURE BUILDING INTO THE AREA. GOING INTO EARLY NEXT WEEK MADE LITTLE CHANGES OVERALL TO THE FORECAST WITH 00Z ECMWF SHOWING BROAD UPPER TROUGH MOVING ACROSS THE AREA WHILE GFS ALSO BRINGING UPPER TROUGH OVER THE AREA BUT A BIT STRONGER WITH SFC LOW PRESSURE DEVELOPING OVER THE MID MISSISSIPPI VALLEY. FOR NOW WILL CONTINUE TO LEAN TOWARD THE ECMWF WITH MAINLY DRY CONDITIONS...BUT HAVE CONTINUE WITH MORE CLOUDINESS ACROSS THE AREA DURING THIS TIME. WITH NO STRONG TEMP ADVECTION MODERATED TEMPS FOR SUNDAY WITH THE TROUGH DEPARTING BUT OTHERWISE KEPT THEM NEAR NORMAL FOR EARLY NEXT WEEK. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... A WEAK COLD FRONT FROM LAKE ERIE ACROSS SRN MI WILL CONTINUE MOVING SOUTH OVER NRN OH TODAY. SATELLITE SHOWING SOME CLOUDS ALONG THE FRONT SO WENT WITH SCT-BKN 060-080 ACROSS SITES. MODELS SHOWING THE POSSIBILITY OF SOME SHRA DEVELOPING ALONG THE FRONT LATER THIS MORNING AND INTO THE AFTERNOON...BUT FOR LOCATIONS SUCH AS TOL-CLE THINKING THAT ANY DEVELOPMENT WOULD OCCUR SOUTH OF THOSE SITES. OVERALL GIVEN LOW PROBABILITIES DID MENTION SOME VCSH AT SEVERAL SITES INCLUDING FDY-MFD-CAK-YNG. TOO LOW CONF AT ERI TO INCLUDE VCSH. ALSO...GIVEN SUCH ISOLATED PROBABILITIES WILL HOLD OFF ON THUNDER AT SITES. SOUTHWEST WINDS SHIFTING W THEN NORTHERLY THROUGH TODAY WITH FROPA. HIGH CLOUDS WILL QUICKLY BUILD IN FROM THE WEST LATE TODAY AND THROUGH TONIGHT WITH NEXT WEATHER SYSTEM. CIGS LOWER TOWARD 10K FT LATER TONIGHT WITH MAINLY NE FLOW DEVELOPING. POSSIBLE MVFR VIS DEVELOPING BUT LATE IN PERIOD SO WILL LET NEXT SHIFT EVALUATE PROBABILITY OF THAT. .OUTLOOK...PERIODS OF NON VFR POSSIBLE THURSDAY AND FRIDAY ACROSS ALL SITES. NON VFR POSSIBLE SATURDAY ACROSS EASTERN SITES. && .MARINE... A WEAK COLD FRONT WILL MOVE ACROSS THE LAKE TODAY BUT SHOULD CAUSE ANY SIGNIFICANT WEATHER OTHER THAN THE WIND SHIFT FROM SOUTHWEST TO NORTH TONIGHT. THE SIGNIFICANT WEATHER ISSUE FOR THE LAKE WILL BEGIN THURSDAY AS A STRONG UPPER TROUGH MOVES TOWARD THE LAKE AND SFC LOW PRESSURE INTENSIFIES OVER THE OHIO VALLEY...THEN MOVES TO THE NORTHEAST FRIDAY. NORTHEAST FLOW WILL INCREASE THROUGH THURSDAY WITH WINDS RANGING 20 KNOTS OR GREATER BY THURSDAY NIGHT AND CONTINUING THROUGH FRIDAY NIGHT. WINDS WILL SLOWLY DIMINISH THROUGH SATURDAY. HIGH PRESSURE WILL BUILD OVER THE LAKE ON SUNDAY. SMALL CRAFT ADVISORY CONDITIONS APPEAR LIKELY BEGINNING THURSDAY NIGHT AND CONTINUING THROUGH AT LEAST SATURDAY MORNING. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...NONE. PA...NONE. MARINE...NONE. && $$ SYNOPSIS...KUBINA NEAR TERM...KUBINA SHORT TERM...KUBINA LONG TERM...ABE AVIATION...ABE MARINE...ABE
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
627 AM EDT WED AUG 8 2012 .SYNOPSIS... A WEAK COLD FRONT JUST NORTH OF LAKE ERIE WILL MOVE SOUTHEAST ACROSS THE LOCAL AREA TODAY AND THEN STALL NEAR THE OHIO RIVER. LOW PRESSURE WILL MOVE UP THE OHIO VALLEY THURSDAY AND FRIDAY. HIGH PRESSURE WILL SLOWLY BUILD OVER THE REGION FROM THE WEST OVER THE WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... UPDATE ALREADY OUT. THE LATEST HRRR NOW SHOWING SCATTERED STORMS DEVELOPING ALONG THE COLD FRONT THIS AFTERNOON. HAVE RAISED PRECIP CHANCES SLIGHTLY OVER THE SE 1/3 OF THE AREA. MINOR ADJUSTMENTS TO THE SKY COVER AS WELL. PREVIOUS...THE COLD FRONT IS ON TRACK TO MOVE SE ACROSS THE AREA TODAY. SOME SHOWERS AND EVEN SOME LIGHTNING OCCURRED EARLIER IN THE NIGHT ALONG THE FRONT ACROSS LOWER MICHIGAN. LATEST HRRR AND CONVECTIVE SREF CONTINUE TO SUGGEST THAT ISOLATED TO SCATTERED SHOWERS AND STORMS WILL DEVELOP ALONG THE FRONT LATER TODAY. BEST CHANCES FOR THIS WILL BE IN THE EAST THIS AFTERNOON. HAVE GONE WITH A 20 TO 30 POP MOST AREAS. CLOUDS WILL COME AND GO TODAY BUT BY LATE AFTERNOON SKIES SHOULD BE MAINLY PARTLY CLOUDY. HIGH TEMPS WILL BE A DEGREE OR TWO COOLER THAN TUESDAY. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/... ACTIVE WEATHER IS EXPECTED DURING THE PERIOD AS AN UPPER LOW GETS SET UP OVER THE EASTERN CONUS. THE MODELS NOW ARE FAIRLY SIMILAR WITH THE MAIN FEATURES. LOW PRESSURE IS EXPECTED TO MOVE UP THE OHIO VALLEY TONIGHT AND FRIDAY WITH THE LOW EVENTUALLY CROSSING WESTERN PA. MODELS SHOWING GOOD ISENTROPIC LIFT WITH PWAT VALUES EVENTUALLY REACHING 1.75 INCHES. INSTABILITY WILL INCREASE TONIGHT AND THURSDAY AS DEWPOINTS SURGE INTO THE UPPER 60S. A FEW STRONG TO SEVERE STORMS ARE LIKELY LATE THURSDAY AS THE LOW PASSES. SHEAR WILL BE ENHANCED ALONG THE FRONT STRETCHING NE FROM THE LOW. THAT IS LIKELY WHERE ANY SEVERE WEATHER WILL OCCUR. WRAP AROUND MOISTURE BEHIND THE LOW WILL KEEP SHOWERS GOING THROUGH MIDDAY SATURDAY ALL AREAS AND IN THE EAST ON SATURDAY NIGHT. 850 MB TEMPS DIP TO PLUS 8 OR 10 SATURDAY DEPENDING ON WHICH MODEL YOU BELIEVE. EITHER WAY COLD AIR ADVECTION CLOUDS AND SHOWERS WILL BE LIKELY TO THE EAST OF KCLE. EXPECT MUCH OF THE AREA TO SEE AN INCH OR MORE OR RAIN THURSDAY THROUGH FRIDAY. TEMPS DURING THE PERIOD WILL BE BELOW NORMAL FOR A CHANGE. && .LONG TERM /SUNDAY THROUGH TUESDAY/... MODELS CONTINUING TO HANDLE STRONG UPPER TROUGH OVER THE AREA WELL WITH GFS AND ECMWF MOVING IT OFF TO THE EAST ON SUNDAY WITH SFC HIGH PRESSURE BUILDING INTO THE AREA. GOING INTO EARLY NEXT WEEK MADE LITTLE CHANGES OVERALL TO THE FORECAST WITH 00Z ECMWF SHOWING BROAD UPPER TROUGH MOVING ACROSS THE AREA WHILE GFS ALSO BRINGING UPPER TROUGH OVER THE AREA BUT A BIT STRONGER WITH SFC LOW PRESSURE DEVELOPING OVER THE MID MISSISSIPPI VALLEY. FOR NOW WILL CONTINUE TO LEAN TOWARD THE ECMWF WITH MAINLY DRY CONDITIONS...BUT HAVE CONTINUE WITH MORE CLOUDINESS ACROSS THE AREA DURING THIS TIME. WITH NO STRONG TEMP ADVECTION MODERATED TEMPS FOR SUNDAY WITH THE TROUGH DEPARTING BUT OTHERWISE KEPT THEM NEAR NORMAL FOR EARLY NEXT WEEK. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... A WEAK COLD FRONT N OF LAKE ERI ACROSS SRN MI WILL CONTINUE TO SLOWLY MOVE SOUTH ACROSS SITES THROUGH TODAY. RADAR SHOWING ONE ISOL SHRA MOVING INTO NW OH SO WILL HAVE TO WATCH TOL...BUT NOT THINKING MUCH FOR IMPACT. OTHERWISE EXPECTING SOME CLOUDS TO DEVELOP LATER THIS MORNING AND AFTN ACROSS NRN OH AHEAD OF THE FRONT. THERE MAY BE SOME ISOL SHRA WITH IT BUT NOT CONFIDENT ON OCCURRENCE OR TIMING AT ANY PARTICULAR SITES. AT THIS TIME WOULD THINK MFD-CAK-YNG WOULD HAVE BEST CHANCE FOR SHRA THIS AFTN. SOUTH WINDS WILL GRADUALLY TURN NORTH AFTER FROPA THROUGH TODAY. .OUTLOOK...PERIODS OF NON VFR POSSIBLE THURSDAY AND FRIDAY ACROSS ALL SITES. NON VFR POSSIBLE SATURDAY ACROSS EASTERN SITES. && .MARINE... A WEAK COLD FRONT WILL MOVE ACROSS THE LAKE TODAY BUT SHOULD CAUSE ANY SIGNIFICANT WEATHER OTHER THAN THE WIND SHIFT FROM SOUTHWEST TO NORTH TONIGHT. THE SIGNIFICANT WEATHER ISSUE FOR THE LAKE WILL BEGIN THURSDAY AS A STRONG UPPER TROUGH MOVES TOWARD THE LAKE AND SFC LOW PRESSURE INTENSIFIES OVER THE OHIO VALLEY...THEN MOVES TO THE NORTHEAST FRIDAY. NORTHEAST FLOW WILL INCREASE THROUGH THURSDAY WITH WINDS RANGING 20 KNOTS OR GREATER BY THURSDAY NIGHT AND CONTINUING THROUGH FRIDAY NIGHT. WINDS WILL SLOWLY DIMINISH THROUGH SATURDAY. HIGH PRESSURE WILL BUILD OVER THE LAKE ON SUNDAY. SMALL CRAFT ADVISORY CONDITIONS APPEAR LIKELY BEGINNING THURSDAY NIGHT AND CONTINUING THROUGH AT LEAST SATURDAY MORNING. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...NONE. PA...NONE. MARINE...NONE. && $$ SYNOPSIS...KUBINA NEAR TERM...KUBINA SHORT TERM...KUBINA LONG TERM...ABE AVIATION...ABE MARINE...ABE
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
339 AM EDT WED AUG 8 2012 .SYNOPSIS... A WEAK COLD FRONT JUST NORTH OF LAKE ERIE WILL MOVE SOUTHEAST ACROSS THE LOCAL AREA TODAY AND THEN STALL NEAR THE OHIO RIVER. LOW PRESSURE WILL MOVE UP THE OHIO VALLEY TONIGHT AND FRIDAY. HIGH PRESSURE WILL SLOWLY BUILD OVER THE REGION FROM THE WEST OVER THE WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... THE COLD FRONT IS ON TRACK TO MOVE SE ACROSS THE AREA TODAY. SOME SHOWERS AND EVEN SOME LIGHTNING OCCURRED EARLIER IN THE NIGHT ALONG THE FRONT ACROSS LOWER MICHIGAN. LATEST HRRR AND CONVECTIVE SREF CONTINUE TO SUGGEST THAT ISOLATED TO SCATTERED SHOWERS AND STORMS WILL DEVELOP ALONG THE FRONT LATER TODAY. BEST CHANCES FOR THIS WILL BE IN THE EAST THIS AFTERNOON. HAVE GONE WITH A 20 TO 30 POP MOST AREAS. CLOUDS WILL COME AND GO TODAY BUT BY LATE AFTERNOON SKIES SHOULD BE MAINLY PARTLY CLOUDY. HIGH TEMPS WILL BE A DEGREE OR TWO COOLER THAN TUESDAY. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/... ACTIVE WEATHER IS EXPECTED DURING THE PERIOD AS AN UPPER LOW GETS SET UP OVER THE EASTERN CONUS. THE MODELS NOW ARE FAIRLY SIMILAR WITH THE MAIN FEATURES. LOW PRESSURE IS EXPECTED TO MOVE UP THE OHIO VALLEY TONIGHT AND FRIDAY WITH THE LOW EVENTUALLY CROSSING WESTERN PA. MODELS SHOWING GOOD ISENTROPIC LIFT WITH PWAT VALUES EVENTUALLY REACHING 1.75 INCHES. INSTABILITY WILL INCREASE TONIGHT AND THURSDAY AS DEWPOINTS SURGE INTO THE UPPER 60S. A FEW STRONG TO SEVERE STORMS ARE LIKELY LATE THURSDAY AS THE LOW PASSES. SHEAR WILL BE ENHANCED ALONG THE FRONT STRETCHING NE FROM THE LOW. THAT IS LIKELY WHERE ANY SEVERE WEATHER WILL OCCUR. WRAP AROUND MOISTURE BEHIND THE LOW WILL KEEP SHOWERS GOING THROUGH MIDDAY SATURDAY ALL AREAS AND IN THE EAST ON SATURDAY NIGHT. 850 MB TEMPS DIP TO PLUS 8 OR 10 SATURDAY DEPENDING ON WHICH MODEL YOU BELIEVE. EITHER WAY COLD AIR ADVECTION CLOUDS AND SHOWERS WILL BE LIKELY TO THE EAST OF KCLE. EXPECT MUCH OF THE AREA TO SEE AN INCH OR MORE OR RAIN THURSDAY THROUGH FRIDAY. TEMPS DURING THE PERIOD WILL BE BELOW NORMAL FOR A CHANGE. && .LONG TERM /SUNDAY THROUGH TUESDAY/... MODELS CONTINUING TO HANDLE STRONG UPPER TROUGH OVER THE AREA WELL WITH GFS AND ECMWF MOVING IT OFF TO THE EAST ON SUNDAY WITH SFC HIGH PRESSURE BUILDING INTO THE AREA. GOING INTO EARLY NEXT WEEK MADE LITTLE CHANGES OVERALL TO THE FORECAST WITH 00Z ECMWF SHOWING BROAD UPPER TROUGH MOVING ACROSS THE AREA WHILE GFS ALSO BRINGING UPPER TROUGH OVER THE AREA BUT A BIT STRONGER WITH SFC LOW PRESSURE DEVELOPING OVER THE MID MISSISSIPPI VALLEY. FOR NOW WILL CONTINUE TO LEAN TOWARD THE ECMWF WITH MAINLY DRY CONDITIONS...BUT HAVE CONTINUE WITH MORE CLOUDINESS ACROSS THE AREA DURING THIS TIME. WITH NO STRONG TEMP ADVECTION MODERATED TEMPS FOR SUNDAY WITH THE TROUGH DEPARTING BUT OTHERWISE KEPT THEM NEAR NORMAL FOR EARLY NEXT WEEK. && .AVIATION /08Z WEDNESDAY THROUGH SUNDAY/... A WEAK COLD FRONT N OF LAKE ERI ACROSS SRN MI WILL CONTINUE TO SLOWLY MOVE SOUTH ACROSS SITES THROUGH TODAY. RADAR SHOWING ONE ISOL SHRA MOVING INTO NW OH SO WILL HAVE TO WATCH TOL...BUT NOT THINKING MUCH FOR IMPACT. OTHERWISE EXPECTING SOME CLOUDS TO DEVELOP LATER THIS MORNING AND AFTN ACROSS NRN OH AHEAD OF THE FRONT. THERE MAY BE SOME ISOL SHRA WITH IT BUT NOT CONFIDENT ON OCCURRENCE OR TIMING AT ANY PARTICULAR SITES. AT THIS TIME WOULD THINK MFD-CAK-YNG WOULD HAVE BEST CHANCE FOR SHRA THIS AFTN. SOUTH WINDS WILL GRADUALLY TURN NORTH AFTER FROPA THROUGH TODAY. .OUTLOOK...PERIODS OF NON VFR POSSIBLE THURSDAY AND FRIDAY ACROSS ALL SITES. NON VFR POSSIBLE SATURDAY ACROSS EASTERN SITES. && .MARINE... A WEAK COLD FRONT WILL MOVE ACROSS THE LAKE TODAY BUT SHOULD CAUSE ANY SIGNIFICANT WEATHER OTHER THAN THE WIND SHIFT FROM SOUTHWEST TO NORTH TONIGHT. THE SIGNIFICANT WEATHER ISSUE FOR THE LAKE WILL BEGIN THURSDAY AS A STRONG UPPER TROUGH MOVES TOWARD THE LAKE AND SFC LOW PRESSURE INTENSIFIES OVER THE OHIO VALLEY...THEN MOVES TO THE NORTHEAST FRIDAY. NORTHEAST FLOW WILL INCREASE THROUGH THURSDAY WITH WINDS RANGING 20 KNOTS OR GREATER BY THURSDAY NIGHT AND CONTINUING THROUGH FRIDAY NIGHT. WINDS WILL SLOWLY DIMINISH THROUGH SATURDAY. HIGH PRESSURE WILL BUILD OVER THE LAKE ON SUNDAY. SMALL CRAFT ADVISORY CONDITIONS APPEAR LIKELY BEGINNING THURSDAY NIGHT AND CONTINUING THROUGH AT LEAST SATURDAY MORNING. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...NONE. PA...NONE. MARINE...NONE. && $$ SYNOPSIS...KUBINA NEAR TERM...KUBINA SHORT TERM...KUBINA LONG TERM...ABE AVIATION...ABE MARINE...ABE
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
157 AM EDT WED AUG 8 2012 .SYNOPSIS... HIGH PRESSURE CENTERED OVER THE OHIO VALLEY WILL CONTINUE THE DRY WEATHER OVERNIGHT TONIGHT. A WEAK COLD FRONT UNDERNEATH A MID LEVEL DISTURBANCE WILL SLIP DOWN FROM THE NORTH ON WEDNESDAY AND REMAIN NEAR THE OHIO RIVER THROUGH THURSDAY. A STRONG UPPER LOW WILL MOVE INTO THE OHIO VALLEY REGION THURSDAY NIGHT AND FRIDAY INCREASING THE CHANCE FOR PRECIPITATION. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... HIGH PRESSURE WILL BRING MOSTLY CLEAR SKIES TO OUR AREA TO START THE OVERNIGHT PERIOD. A WEAK DISTURBANCE APPROACHING THE NORTHERN ZONES LATE TONIGHT MAY BRING SOME SCATTERED LOW AND MID LEVEL CLOUDS ACROSS THOSE ZONES. THE HRRR AND RAP TRY TO PRODUCE ISOLATED SHOWERS WITH THIS FEATURE AROUND DAYBREAK. HAVE HELD OFF ON ANY MENTIONABLE CHANCES FOR PRECIP AS THE NORTHERN ZONES HAVE DEWPOINTS GENERALLY IN THE UPPER 50S...SO ANYTHING THAT DOES DEVELOP WILL PROBABLY NOT HAVE PRECIP REACH THE SURFACE. TEMPERATURES HAVE BEEN SLOW TO DROP OFF ACROSS MOST OF THE SOUTHWEST...AND DAYTON...WILMINGTON...AND COLUMBUS METRO AREA. HAVE THEREFORE TWEAKED UP OVERNIGHT LOWS IN THESE AREAS. ALSO OF NOTE IS THE UPPER 60S DEWPOINTS THAT HAVE FOUND THEIR WAY INTO OUR AREA BETWEEN THE EASTERN CINCINNATI METRO AREA AND PORTSMOUTH. THIS COULD BE A PRECURSOR TO FOG DEVELOPMENT LATER TONIGHT ESPECIALLY ACROSS THE RIVER VALLEYS. && .SHORT TERM /6 AM THIS MORNING THROUGH THURSDAY NIGHT/... A WEAK COLD FRONT WILL DROP SOUTH INTO THE REGION ON WEDNESDAY. THERE IS LITTLE SUPPORT FOR CONVECTION BUT IT WILL BRING A SLIGHT CHANCE TO PARTS OF THE FA. THE FRONT WILL BECOME NEARLY STATIONARY NEAR THE OHIO RIVER. TEMPERATURES ON WEDNESDAY WILL WARM UP COMPARED TO TODAY AS WWA TAKES OVER AHEAD OF THE NEXT STRONG UPPER LEVEL TROF. EXPECT TEMPERATURES IN THE MID 90S SOUTH TO UPPER 80S EXTREME NORTH. BOTH ECMWF AND GFS HAVE A LOW DEVELOPING SW ALONG THE FRONT AND MOVING INTO THE REGION THURSDAY/THURSDAY NIGHT. THE MODELS DIFFER THOUGH ON STRENGTH AND EXACT PLACEMENT OF THE LOW WHICH WILL ULTIMATELY EFFECT PRECIPITATION LOCATION AND AMOUNTS. HAVE CHANCE POPS THURSDAY INCREASING THEM TO LIKELY THURSDAY NIGHT AS DEEPER UPPER LEVEL TROF APPROACHES FORECAST AREA. THE HIGH TEMPERATURES WILL BE A FEW DEGREES COOLER ON THURSDAY WITH AN INCREASE IN CLOUDS. THE LOW TEMPERATURES WILL BE IN THE MID TO UPPER 60S WEDNESDAY NIGHT AND THURSDAY NIGHT. && .LONG TERM /FRIDAY THROUGH TUESDAY/... MODELS CONTINUE TO HAVE DIFFICULTY RESOLVING THE TIMING AND STRENGTH OF DIGGING S/WV TROF INTO THE GREAT LAKES ON FRIDAY AND HOW LONG IT LINGERS INTO THE FIRST PART OF THE UPCOMING WEEKEND. ATTM...HAVE USED A BLEND OF THE 00Z ECMWF AND NCEP HPC GUIDANCE IN WHICH SFC LOW PRESSURE IS MORE SUBDUED AND RIPPLES ALONG OLD FRONTAL BOUNDARY ALONG THE OHIO RIVER ON FRIDAY. THIS SOLUTION CALLS FOR LIKELY POPS AND TEMPERATURES ON THE COOLER SIDE DUE TO CLOUDS...PCPN...AND SOME LOCATIONS UNDER THE INFLUENCE OF A NORTHERLY FLOW ON THE BACK SIDE OF THE LOW. HOWEVER...IT MUST BE NOTED THAT THE NEW 12Z ECMWF IS GIVING INDICATIONS SIMILAR TO THE 12Z GFS THAT PERHAPS THE SFC LOW WILL DEEPEN AND TRACK FARTHER NW ALONG I-71. THIS LATTER SOLUTION WOULD BRING A SHARPER TEMPERATURE GRADIENT TO THE REGION AND COULD POSE A SMALL RISK OF SEVERE WEATHER TO AREAS LOCATED SE OF THE LOW TRACK. HOPEFULLY...LATER MODEL RUNS WILL RESOLVE THIS DILEMMA...BUT MODELS TEND TO HAVE DIFFICULTY IN DIGGING AND DEVELOPING CLOSED MID LEVEL CIRCULATIONS. FOR FRIDAY NIGHT NIGHT INTO SATURDAY NIGHT...AGAIN...A QUICKER UPR LVL LOW MOTION TO THE NE WAS USED BUT MAY END UP BEING SLOWER THAN CURRENTLY FORECAST DUE TO RECENT MODEL GUIDANCE. HAVE A CHANCE OF SHOWERS DIMINISHING WEST TO EAST THROUGH THIS PERIOD ALONG WITH GRADUAL CLEARING SATURDAY INTO SATURDAY NIGHT. TEMPERATURES ON SATURDAY WILL BE CLOUD DEPENDENT AND HAVE GONE WITH HIGHS IN THE MID TO UPPER 70S. LOWS SATURDAY NIGHT WILL BE COOL AS SURFACE HIGH PRESSURE BUILDS INTO THE REGION. FOR THE REMAINDER OF THE EXTENDED...SUNDAY THROUGH TUESDAY...THE GREAT LAKES AND OHIO VALLEY AREA WILL BE UNDER A NORTHWEST FLOW PATTERN ALOFT. THERE ARE INDICATIONS THAT A FEW WEAK DISTURBANCES WILL RIPPLE SE WITHIN THIS FLOW...BRINGING A SMALL THREAT FOR PCPN. GIVEN THAT THEY APPEAR WEAK ATTM AND TIMING IS DIFFICULT AT BEST AT THIS JUNCTURE...HAVE MAINTAINED A DRY FORECAST ALONG WITH MODIFYING TEMPERATURES AS HEIGHTS AND TEMPERATURES ALOFT RISE THROUGH THE PERIOD. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... SEEING SOME 8K FT AC DEVELOPING ACROSS THE MIAMI AND WHITEWATER VALLEYS. THIS IS EXPECTED TO GRADUALLY WORK EWD OVERNIGHT. KEPT THESE CLDS SCT FOR THE OVERNIGHT. MVFR AND POSSIBLE SOME IFR FOG ARE POSSIBLE UNTIL 12Z AT ILN AND LUK. WEAK CDFNT WORKS INTO THE FA TODAY. MOISTURE IS RATHER LIMITED...SO ONLY EXPECT CLDS DEVELOPMENT WITH THE FNTL LIFT. MODELS ARE SUGGESTING THAT THE BEST CLDS COVER WILL BE DURING THE LATE AFTN ALONG FRONT WHEN IT REACH AN ARC FROM CMH-PMH-CVG. WENT A WITH A BROKEN AC DECK AT CVG/LUK...BUT LEFT THE CLDS SCT AT THE OTHER TAFS. UPPER LEVEL MOISTURE WILL BEGIN TO INCREASE AFT 00Z AHEAD OF A STRONGER SYSTEM THAT IS DIGGING INTO THE MS VALLEY. .OUTLOOK...THUNDERSTORMS ARE POSSIBLE ON THURSDAY AND FRIDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...PARKER NEAR TERM...LATTO SHORT TERM...PARKER LONG TERM...HICKMAN AVIATION...SITES
AREA FORECAST DISCUSSION
NWS TULSA OK
343 PM CDT WED AUG 8 2012 .DISCUSSION... ONGOING CONVECTION WILL MAINTAIN A RISK OF DAMAGING DOWNBURST WINDS ACROSS SE OK AND WESTERN AR INTO SUNSET...WITH ATTENTION THEN TURNING TO EXPANDING CONVECTION ACROSS THE CENTRAL PLAINS. THIS CONVECTION WILL BE FORCED BY A RESPECTABLE MID LEVEL WAVE FOR EARLY AUGUST...AND LIKELY DEVELOP SOUTH AND EASTWARD AFTER SUNSET. GIVEN THE DEEPLY MIXED AND NOT-YET OVERTURNED BOUNDARY LAYER IN PLACE ACROSS NE OK...THE CONVECTION WILL HAVE A GOOD CHANCE OF DEVELOPING INTO THE REGION. THE SOUTHWARD EXTENT SHOULD BE LIMITED BY THE ONGOING CONVECTION AND ITS EFFECTS ON STABILIZING THE BOUNDARY LAYER. THIS SCENARIO IS LARGELY SUPPORTED BY THE 18Z NAM AND HRRR OUTPUT. THE COLD FRONT ASSOCIATED WITH THE PASSING WAVE WILL MOVE INTO NE OK BY SUNRISE THURSDAY...AND THROUGH MUCH OF THE FORECAST AREA BY SUNSET THURSDAY. STORM CHANCES WILL RESIDE ALONG AND SOUTH OF THE BOUNDARY PRIMARILY DURING THE AFTERNOON HOURS ON THURSDAY. NOTICEABLY DRIER AND COOLER AIR WILL FOLLOW THE FRONT AND BRING TEMPS NEAR NORMAL FRIDAY AND SATURDAY. RAINFALL FOOTPRINTS...OR LACK THEREOF...MAY LARGELY AFFECT THE DEGREE OF COOLING GIVEN THE VERY WARM GROUND TEMPS AND LACK OF CLOUD COVER BEHIND THE FRONT. UPPER RIDGING WILL ATTEMPT TO EXPAND BACK EASTWARD OVER THE WEEKEND...THOUGH IT LOOKS TO BE SUPPRESSED FURTHER SOUTH AND NOT HAVE AS STRONG AS INFLUENCE AS RECENTLY. SOUTHERN PERIPHERY OF A PASSING WAVE MAY SUPPORT PRECIP LATE SUNDAY INTO MONDAY...OTHERWISE NO SIGNIFICANT PRECIP CHANCES ARE NOTED UNTIL POSSIBLY JUST BEYOND THIS FORECAST TIME FRAME. && .PRELIMINARY POINT TEMPS/POPS... TUL 75 100 69 92 / 30 0 10 0 FSM 78 104 70 93 / 30 20 10 0 MLC 74 103 69 94 / 30 20 10 0 BVO 69 99 64 92 / 30 0 10 0 FYV 67 97 64 87 / 40 10 10 0 BYV 70 95 66 85 / 50 10 10 0 MKO 73 102 69 93 / 40 0 10 0 MIO 71 97 68 88 / 40 0 10 0 F10 75 102 70 93 / 30 10 10 0 HHW 75 103 73 95 / 30 30 10 0 && .TSA WATCHES/WARNINGS/ADVISORIES... OK...NONE. AR...NONE. && $$ LONG TERM....07
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1112 AM EDT WED AUG 8 2012 .SYNOPSIS... A BROAD UPPER LEVEL TROUGH OVER THE EASTERN U.S. WILL UNDERGO SIGNIFICANT AMPLIFICATION THROUGH THE END OF THE WEEK. THIS FEATURE AND ITS ASSOCIATED FRONTAL SYSTEM WILL BRING RAIN AND THUNDERSTORMS TO THE AREA INTO THE FIRST PART OF THE WEEKEND. FAIR WEATHER SHOULD RETURN BY LATE IN THE WEEKEND OR EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... WEAK FRONTAL BOUNDARY ACROSS NW PA WILL BE FOCUS OF SCATTERED CONVECTION THIS AFTERNOON. ANY STORMS THAT DO FORM WILL DRIFT SOUTHEAST ACROSS THE CWA. AFTERNOON CAPES WILL BE MARGINAL AND SHEAR WEAK...THOUGH LATEST HRRR RUNS DEVELOP CONVECTION. WILL RAISE POPS SLIGHTLY IN NW ZONES TO ACCOUNT FOR THIS. STILL NOT EXPECTING MUCH MORE THEN PULSE STORMS. ANOTHER BOUNDARY SE OF PA WILL BE CLOSE ENOUGH TO SE ZONES TO BRING A CHANCE OF AFTERNOON CONVECTION...BUT LACK OF TRIGGER AND WARMER MID LEVEL TEMPS SUGGESTS NOTHING MORE THAN AN ISOLD PULSE STORM. OVERALL CONVECTIVE CVRG SHOULD BE LIMITED AND CAPPED POPS AT 30 PCT. THE WEAK FRONT WILL SETTLE SLOWLY SEWD NEAR I-80 OVERNIGHT. A FEW SHOWERS OR TSTMS MAY STILL LINGER NEAR THE DIFFUSE FRONT...BUT THE LOSS OF HEATING/INSTABILITY SHOULD AFFORD A DRY NIGHT IN MOST LOCATIONS. HI/LO TEMPS THIS PD WILL AVG A FEW TO SEVERAL DEGS ABV NORMAL. && .SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/... SIGNIFICANT AMPLIFICATION OF THE ERN TROUGH IS EXPECTED TO BEGIN THIS PERIOD...AS POTENT S/W AND ATTENDANT MID-LVL JET DROP SEWD INTO THE GRT LKS AND MID MS VLY. AT THE SFC...THE BAROCLINIC/FRONTAL ZONE SHOULD BECOME MORE DEFINED IN TIME WITH ONE OR MORE SFC WAVES DEVELOPING IN THE OH VLY. THE ERN PORTION OF THE WAVY FNTL BNDRY SHOULD REMAIN Q-STNRY OVR CENTRAL PA THRU THURS NIGHT. SPC HAS MAINTAINED THE SLIGHT RISK FOR ALL OF THE CWA FOR D2. THE SLIGHTLY ELEVATED SVR THREAT..WHEN COMPARED TO THE D1 SEE TEXT... IS SUPPORTED BY STRONGER DEEP LYR FORCING/HEIGHT FALLS AND WINDS ALOFT. 1500-2000 J/KG OF ML CAPE AND FAIRLY STEEP MID-LVL LAPSE RATES SHOULD ALSO ENHANCE DMGG WIND THREAT VIA LOOSELY ORGANIZED MULTI-CELL CLUSTERS. THE WELL-DEFINED POS TILT S/W TROUGH WILL ROTATE EWD THRU THE MIDWEST TWD THE UPPER OH VLY BY THE END OF THE PD. MDL DATA SHOWS AN AXIS OF MOD-HVY RNFL SETTING UP ALONG SEWD ADVANCING FNTL ZONE JUST DOWNWIND OF THE LWR GRT LKS. INC SWLY FLOW AHEAD OF DEEPENING SFC WAVE EJECTING NEWD THRU THE OH VLY SHOULD DRAW HI PWATS NEWD INTO NW PA. FAVORABLE UPPER JET DYNAMICS AND STRONG LLVL CONVERGENCE SHOULD SUPPORT 0.50-1 INCH QPF AXIS OVR THIS REGION AND HAVE INCREASED POPS INTO THE LOW CATG RANGE. A NON-GFS SOLUTION IS PREFERRED WITH THIS SYSTEM. && .LONG TERM /FRIDAY THROUGH TUESDAY/... THE ANOMALOUS MID-UPPER TROUGH IS FORECAST TO EVOLVE INTO A CLOSED LOW INVOF LWR MI ON FRIDAY...AND THEN LIFT SLOWLY NWD ACRS THE LWR GRT LKS INTO SRN ONT ON SAT BEFORE ACCELERATING INTO QUEBEC ON SUNDAY. CONCERNING THE H5 LOW POSITION...THE GFS IS A NRN OUTLIER WITH THIS SYSTEM AND THE 00Z GEFS AND 12Z ECENS MEAN SUPPORT A MORE SOUTHERLY/SLOWER SOLUTION ALOFT PER THE REMAINING DETERMINISTIC GLOBAL MODEL CONSENSUS -- 00Z UKMET/CANADIAN/ECMWF. SEVERAL WEAK WAVES OF LOW PRES IN THE OH VLY WILL CONSOLIDATE INTO ONE MAIN SFC LOW INVOF LAKE ERIE EARLY FRI BEFORE OCCLUDING NWWD OVR THE LWR LKS TWD LAKE HURON BY SATURDAY. THE WARM FRONT ATTENDANT TO THE SFC LOW WILL LIFT NEWD THRU PA INTO NEW ENGLAND WHILE THE TRAILING COLD FRONT PIVOTS EWD ACRS THE UPPER OH VLY AND PUSHES SLOWLY EWD THRU CENTRAL PA. A SSW-NNE ORIENTED MOD-HVY QPF AXIS SHOULD BE ONGOING AT THE START OF THE PERIOD ACRS NW PA NEAR SFC LOW TRACK. GENERALLY LIGHTER BASIN-AVG QPF AMTS...MORE CONVECTIVE IN NATURE... ARE ANTICIPATED FURTHER TO THE EAST ACRS THE CENTRAL MTNS AND SUSQ VLY LATER FRIDAY AND INTO FRI NGT ALONG/AHEAD OF THE COLD FRONT. STRONG JET DYNAMICS AND FRONTAL LIFT/CONVERGENCE COULD PRODUCE HVY RNFL RATES WITH PLENTY OF DEEP LYR MSTR AVAILABLE. FOLLOWED HPC PRETTY CLOSELY FOR QPF AMTS WHICH RANGE FROM 1-1.5 INCHES OVR THE NW MTNS TO 0.25-0.50 IN THE LWR SUSQ VLY FOR THE 24HR PD ENDING 00Z SAT. IN ADDITION TO POSSIBLE HVY RAINS...A SVR WEATHER THREAT SHOULD ALSO UNFOLD AHEAD OF THE COLD FRONT IN THE VERY MOIST WARM SECTOR. SPC HAS EXPANDED THE D3 SLIGHT RISK TO ENCOMPASS NEARLY ALL OF THE CWA EAST OF THE ALLEGHENY FRONT. THERE WILL BE A SOMEWHAT CONDITIONAL DMGG WIND THREAT AS STRONG WARMING OCCURS IN CLOUD-BREAKS AND CONTRIBUTES TO POTENTIAL MODERATE INSTABILITY. ANOTHER SCENARIO TO CONSIDER IS THE DEVELOPMENT OF A SECONDARY TRIPLE POINT LOW E OF THE APPLCHNS...WHICH MAY ACT TO ENHANCE LOW LEVEL SHEAR INVOF WARM FRONTAL ZONE NEAR SE PA. BROAD CYC FLOW ALOFT WILL OVERSPREAD THE REGION SAT INTO EARLY SUNDAY WHICH SHOULD ALLOW FOR SCT SHOWER/ISOLD TSTM ACTIVITY. THERE ALSO APPEARS TO BE A DEFORMATION ZONE WHICH COULD SPREAD WRAP- AROUND PCPN INTO THE AREA ON THE BACKSIDE OF THE DEPARTING SYS. PCPN SHOULD COME TO AN END ON SUNDAY AS THE SYSTEM BEGINS TO ACCELERATE NWD. A PERIOD OF FAIR AND FAIRLY UNEVENTFUL WEATHER WILL LKLY FOLLOW INTO EARLY NEXT WEEK AS THE WESTERLIES RELAX TO A QUASI-ZONAL ORIENTATION. && .AVIATION /15Z WEDNESDAY THROUGH SUNDAY/... A WEAKENING COLD FRONT MAY SPARK OFF SOME SCATTERED SHOWERS/STORMS OVER THE NWRN HALF OF THE FCST AREA LATE IN THE DAY...BUT CONFIDENCE IS LOW AS THE FORCING WILL BE WEAK AND PWATS WILL BE NOMINAL. OUTLOOK... THU...VFR WITH SCT SHRA/TSRA POSS AFTN/NIGHT. FRI-SAT...MAINLY VFR BUT RESTRICTIONS LIKELY IN TSRA/SHRA. SUN...SCATTERED SHOWERS/THUNDERSTORMS. RESTRICTIONS POSSIBLE. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...STEINBUGL NEAR TERM...ROSS SHORT TERM...STEINBUGL LONG TERM...STEINBUGL AVIATION...ROSS
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
1011 PM CDT THU AUG 9 2012 .UPDATE... OTHER THAN THE ISOL CONVECTION OVER WESTERN MIDDLE TN...NOT MUCH GOING ON. BOUNDARY STILL LOCATED A GOOD DISTANCE TO OUR NW. NUMERICAL POPS ARE QUITE LOW THROUGH 12Z. HRRR NOW SHOWING SOME REDEVELOPMENT WITH THE FRONTAL BOUNDARY AFT 08Z OR SO. PRESSURE RISES ARE FAIRLY STRONG NORTH OF THE FRONTAL BOUNDARY. THUS...BOUNDARY SHOULD STILL BE ON THE APPROACH THROUGH 12Z. WILL GO AHEAD AND LOWER POPS TO THE 30-40 PERCENT RANGE FOR THE DURATION. HRRR DOES MAKE A COMEBACK WITH THE CONVECTION BUT PRIMARILY IS SERVING AS THE LONE MODEL...AND EVEN IF THE HRRR PANS OUT...THE ACTIVITY DOES NOT LOOK ALL THAT ORGANIZED. FOR THE UPDATE WILL LOWER POPS. UPDATE OUT SHORTLY. && .PREV DISCUSSION... /ISSUED 703 PM CDT THU AUG 9 2012/ UPDATE...FOR 06Z AVIATION DISCUSSION. AVIATION...06Z AVIATION DISCUSSION. UNCERTAINTIES...SFC FRONTAL MOVEMENT IMPACTS. CONVECTION TO OUR NW AHEAD OF FRONT MAINLY DISSIPATED...AND WITH AN OVERALL DRIER AIRMASS IN PLACE ACROSS THE MID STATE PER MORNING`S CONVECTION...PCPN CHANCES SLIGHT AT BEST THRU 10/10Z AND WILL NOT MENTION. AS SFC FRONT MOVES CLOSER/EVENTUALLY THRU CKV/BNA...EXPECT SOME MOISTURE POOLING IN ITS VICINITY...MENTIONED MVFR FOG/CEILINGS...TEMPO IFR CSV...BUT EVEN WITH POSSIBLE SHORT WAVE PASSAGE IN UPPER LEVEL FLOW AIDING...JUST DOUBT WITH ANY DIURNAL INFLUENCES NOT YET ESTABLISHED...PCPN WILL OCCUR. FRONT SHOULD BE W OF CSV THRU AROUND 10/18Z...AND BELIEVE WITH DIURNAL INFLUENCES KICKING IN...THAT CB/VCTS TSTM CSV APPROPRIATE. PREV DISCUSSION.../ISSUED 602 PM CDT THU AUG 9 2012/ UPDATE... NOT IMPRESSED WITH THE CHANCES FOR CONVECTION OVERNIGHT. ONLY BULLISH TRENDS I SEE ARE WITH THE WRF AND THE FROPA WHICH IS EXPECTED AT 12Z. OTW...UPPER DYNAMICS LOOKING WEAK WITH AN OVERALL DECREASE IN MOISTURE DEPTH FROM 00Z TO 06Z. HRRR SHOWS ZILCH THROUGH 6Z AND UPPER DIVERGENCE QUITE WEAK THROUGH 12Z ON THE GFS AND NAM. I WILL GO AHEAD AND UPDATE GRIDS AD KNOCK POPS DOWN PRIOR TO 06Z. AFT 06Z...WILL KEEP THE LIKELY POPS GOING ACROSS THE NORTH BUT THIS MAY NEED A DOWNWARD YANK AS WELL LATER IN THIS SHIFT. REMAINDER OF FCST LOOKS TO BE IN GOOD SHAPE. NO MENTION OF FOG CURRENTLY AND I SEE NO REASON TO ADD ANY AS TOVERS REMAIN NEAR TO ABOVE 0. MIN TEMP FCST LOOKS TO BE IN GOOD SHAPE. UPDATE OUT SHORTLY. PREV DISCUSSION.../ISSUED 340 PM CDT THU AUG 9 2012/ SHORT TERM...SHOWERS AND CLOUDS THAT STILL LINGERED ALONG THE CUMBERLAND PLATEAU AT MID-AFTERNOON WERE HELPING TO PRODUCE A SIGNIFICANT TEMPERATURE GRADIENT ACROSS THE MID STATE. AT 300 PM...TEMPERATURES RANGED FROM THE UPPER 60S AT CSV TO THE UPPER 80S OVER OUR MOST WESTERN COUNTIES. WITH SHOWERS DEPARTING OUR AREA, FROM THE PLATEAU, WE NOW TURN OUR EYES TO THE WEST, WHERE NEW THUNDERSTORMS WERE POPPING UP IN THE AFTERNOON HEAT, OVER SOUTHWESTERN KENTUCKY. THESE STORMS WERE ALSO OCCURRING ALONG THE EDGE OF A BAND OF MID-T0-UPPER LEVEL DRYING THAT EXTENDED FROM SOUTHERN PARTS OF INDIANA AND ILLINOIS, ACROSS SOUTHEAST MISSOURI INTO CENTRAL ARKANSAS. WITH THE POSSIBILITY OF DRY AIR ENTRAINMENT AT THE MID LEVELS, EXPECT SOME GUSTY DOWNBURSTS TO BE POSSIBLE WITH THESE STORMS AS THEY ADVANCE INTO NORTHWESTERN MIDDLE TENNESSEE LATE THIS AFTERNOON AND EVENING. AFTER THE INITIAL CONVECTION THIS EVENING, THAT DEVELOPS MAINLY OVER THE NORTHWEST, BELIEVE WE WILL SEE MORE THUNDERSTORM DEVELOPMENT LATER TONIGHT, AS UPPER TROUGH DEEPENS OVER THE OHIO RIVER VALLEY, ENERGIZING THE SLEEPY STATIONARY FRONT JUST WEST OF PADUCAH, AND BRINGING IT EASTWARD AS A COLD FRONT. EXPECT THE COLD FRONT TO BE NEAR A BWG-BNA-WAYNESBORO LINE BY 12Z FRIDAY, PUSHING TO NR A MSL-LIVINGSTON LINE BY 18Z, AND OFF THE CUMBERLAND PLATEAU BY LATE FRIDAY AFTERNOON. SPC HAS ALL OF OUR AREA IN A SLIGHT RISK FOR SEVERE THUNDERSTORMS THROUGH 12Z FRIDAY, AS THE FRONT PUSHES IN, AND EXPECT TO SEE SIMILAR STORMS TO THE ONES WE HAD THIS MORNING...VERY WET AND JUICY (WITH TORRENTIAL DOWNPOURS) ALONG WITH THE POSSIBILITY FOR STRONG, GUSTY DOWNBURST WINDS. EXPECT SHOWERS AND STORMS TO FINALLY PUSH EAST OF THE MID STATE FRIDAY EVENING, WITH SEVERAL DAYS OF DRY AND AUTUMN-LIKE CONDITIONS TO FOLLOW OVER THE WEEKEND. EXPECT AFTERNOON DEW POINTS IN THE 50S BOTH SATURDAY AND SUNDAY, WITH DAYTIME HIGHS MAINLY IN THE MIDDLE 80S. MANY PLACES WILL LIKELY SEE LOW TEMPERATURES DROP INTO THE MID TO UPPER 50S SUNDAY MORNING. LONG TERM...AFTER OUR DRY SPELL OVER THE WEEKEND, EXPECT NORTHWEST FLOW TO BECOME MORE ZONAL, WITH TWO OR THREE UPPER LEVEL SHORTWAVES LIKELY TO TRAVERSE THE AREA NEXT WEEK. THE TIMING OF THESE IMPULSES, OF COURSE, IS VERY DIFFICULT. IT`S ALSO DIFFICULT TO KNOW HOW MUCH SHRA/TSRA ACTIVITY EACH ONE WITH BRING WITH IT. THEREFORE, HAVE PAINTED POPS WITH A BROAD BRUSH FOR MOST OF NEXT WEEK, WITH A 20% POP MAKING REPEATED ONSTAGE APPEARANCES. TEMPERATURES WILL WARM BACK TO AROUND 90 DEGREES OR IN THE LOWER 90S FOR AREAS WEST OF THE CUMBERLAND PLATEAU, WITH TEMPS FORECAST TO BE MAINLY IN THE MIDDLE 80S ALONG THE PLATEAU ITSELF. && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 21
AREA FORECAST DISCUSSION
NWS MEMPHIS TN
857 PM CDT THU AUG 9 2012 .UPDATE... DO NOT FEEL LIKE CHANCES FOR STRONG TO SEVERE THUNDERSTORMS ARE VERY HIGH TONIGHT...BUT WITH A FRONT MOVING THROUGH IN MIDDLE AUGUST NOT TOTALLY COMFORTABLE WITH REMOVING IT ALL TOGETHER. LOWERED POPS A BIT. TEMPERATURES LOOK ON TRACK. && .PREV DISCUSSION... /ISSUED 639 PM CDT THU AUG 9 2012/ DISCUSSION... /ISSUED 304 PM CDT THU AUG 9 2012/ SKIES ARE MOSTLY SUNNY THIS AFTERNOON ACROSS MUCH OF THE FORECAST AREA WITH TEMPERATURES RANGING FROM THE MID 80S TO MID 90S. THE AREA OF RAIN THAT WAS OVER PARTS OF NORTH MISSISSIPPI THIS MORNING HAS PUSHED SOUTH. COLD FRONT CURRENTLY EXTENDS FROM EASTERN OHIO THROUGH SOUTHEAST MISSOURI AND INTO THE TEXAS PANHANDLE. A COUPLE OF THUNDERSTORMS HAVE DEVELOPED AHEAD OF THE FRONT OVER WESTERN KENTUCKY AND ARE TRACKING SOUTHEAST TOWARD THE FORECAST AREA. THE COLD FRONT WILL CONTINUE TO TRACK SOUTHEAST TONIGHT WITH SOME ADDITIONAL SCATTERED THUNDERSTORMS EXPECTED TO DEVELOP AHEAD OF THE FRONT. THE FRONT WILL STILL BE OVER NORTH MISSISSIPPI FRIDAY MORNING SO SOME ADDITIONAL SCATTERED THUNDERSTORMS WILL BE POSSIBLE MAINLY OVER AREA SOUTH OF INTERSTATE 40. BEHIND THE FRONT COOLER AND DRIER AIR WILL FILTER INTO THE REGION. TEMPERATURES WILL BE MUCH COOLER WITH HIGHS ONLY IN THE 80S TO AROUND 90. BY FRIDAY NIGHT...THE FRONT WILL BE WELL SOUTH OF THE REGION ENDING THE THREAT OF RAIN. WITH DRIER AIR IN PLACE TEMPERATURES WILL COOL OFF SOME WITH SOME LOCATIONS IN WEST TENNESSEE DROPPING BELOW 60 DEGREES BY SATURDAY MORNING. THE WEEKEND LOOKS TO BE QUITE PLEASANT AS HIGH PRESSURE REMAINS IN PLACE. DRY WEATHER WILL CONTINUE FOR BOTH SATURDAY AND SUNDAY WITH TEMPERATURES MAINLY BELOW NORMAL BOTH DAYS. BY MONDAY...A WEAK COLD FRONT WILL BE APPROACHING THE REGION WITH SOME SCATTERED THUNDERSTORMS POSSIBLE AHEAD OF THE FRONT. THE FRONT WILL CONTINUE TO MOVE SLOWLY SOUTHEAST MONDAY NIGHT AND TUESDAY WITH MORE SCATTERED THUNDERSTORMS POSSIBLE FROM MONDAY NIGHT THROUGH TUESDAY NIGHT. HIGH PRESSURE WILL BRIEFLY BUILD INTO THE REGION ON WEDNESDAY BRINGING A BRIEF END TO THE THREAT OF RAIN. BY WEDNESDAY NIGHT THE COLD FRONT WILL LIFT BACK NORTH AS A WARM FRONT BRINGING A CHANCE OF MORE THUNDERSTORMS FOR WEDNESDAY NIGHT AND MUCH OF THURSDAY. ARS AVIATION... 00Z TAF SET COLD FRONT STILL LOCATED BACK TO THE NORTHWEST BUT LOWER DEWPOINTS HAVE WORKED INTO MUCH OF THE CWA THUS BEGINNING TO HAVE DOUBTS ON TSRA DEVELOPMENT THIS EVENING ALONG THE FRONT. LATEST HRRR RUN DOESN/T SHOW ANYTHING DEVELOPING AND THE NEW NAM SHOWS STUFF DEVELOPING NOT UNTIL THE FRONT IS SOUTH AND EAST OF MEMPHIS. FOR NOW WILL REMOVE MENTION OF VCTS AT KJBR BUT WILL LEAVE VCTS WORDING AT OTHER TAF SITES. SOUTHWEST WINDS AROUND 8-10 KTS WITH HIGHER GUSTS AT TIMES EXPECTED AHEAD OF THE FRONT. WINDS WILL SWITCH TO THE NORTHWEST AND EVENTUALLY TO THE NORTH BEHIND THE FRONT. KRM && .AVIATION... && .PRELIMINARY POINT TEMPS/POPS... MEM 74 87 67 88 / 20 20 10 0 MKL 69 84 59 86 / 30 20 0 0 JBR 71 87 64 89 / 10 10 0 0 TUP 72 89 65 88 / 30 30 10 0 && .MEG WATCHES/WARNINGS/ADVISORIES... AR...NONE. MO...NONE. MS...NONE. TN...NONE. && $$
AREA FORECAST DISCUSSION...UPDATED
NWS NASHVILLE TN
703 PM CDT THU AUG 9 2012 .UPDATE...FOR 06Z AVIATION DISCUSSION. && .AVIATION...06Z AVIATION DISCUSSION. UNCERTAINTIES...SFC FRONTAL MOVEMENT IMPACTS. CONVECTION TO OUR NW AHEAD OF FRONT MAINLY DISSIPATED...AND WITH AN OVERALL DRIER AIRMASS IN PLACE ACROSS THE MID STATE PER MORNING`S CONVECTION...PCPN CHANCES SLIGHT AT BEST THRU 10/10Z AND WILL NOT MENTION. AS SFC FRONT MOVES CLOSER/EVENTUALLY THRU CKV/BNA...EXPECT SOME MOISTURE POOLING IN ITS VICINITY...MENTIONED MVFR FOG/CEILINGS...TEMPO IFR CSV...BUT EVEN WITH POSSIBLE SHORT WAVE PASSAGE IN UPPER LEVEL FLOW AIDING...JUST DOUBT WITH ANY DIURNAL INFLUENCES NOT YET ESTABLISHED...PCPN WILL OCCUR. FRONT SHOULD BE W OF CSV THRU AROUND 10/18Z...AND BELIEVE WITH DIURNAL INFLUENCES KICKING IN...THAT CB/VCTS TSTM CSV APPROPRIATE. && .PREV DISCUSSION.../ISSUED 602 PM CDT THU AUG 9 2012/ UPDATE... NOT IMPRESSED WITH THE CHANCES FOR CONVECTION OVERNIGHT. ONLY BULLISH TRENDS I SEE ARE WITH THE WRF AND THE FROPA WHICH IS EXPECTED AT 12Z. OTW...UPPER DYNAMICS LOOKING WEAK WITH AN OVERALL DECREASE IN MOISTURE DEPTH FROM 00Z TO 06Z. HRRR SHOWS ZILCH THROUGH 6Z AND UPPER DIVERGENCE QUITE WEAK THROUGH 12Z ON THE GFS AND NAM. I WILL GO AHEAD AND UPDATE GRIDS AD KNOCK POPS DOWN PRIOR TO 06Z. AFT 06Z...WILL KEEP THE LIKELY POPS GOING ACROSS THE NORTH BUT THIS MAY NEED A DOWNWARD YANK AS WELL LATER IN THIS SHIFT. REMAINDER OF FCST LOOKS TO BE IN GOOD SHAPE. NO MENTION OF FOG CURRENTLY AND I SEE NO REASON TO ADD ANY AS TOVERS REMAIN NEAR TO ABOVE 0. MIN TEMP FCST LOOKS TO BE IN GOOD SHAPE. UPDATE OUT SHORTLY. PREV DISCUSSION.../ISSUED 340 PM CDT THU AUG 9 2012/ SHORT TERM...SHOWERS AND CLOUDS THAT STILL LINGERED ALONG THE CUMBERLAND PLATEAU AT MID-AFTERNOON WERE HELPING TO PRODUCE A SIGNIFICANT TEMPERATURE GRADIENT ACROSS THE MID STATE. AT 300 PM...TEMPERATURES RANGED FROM THE UPPER 60S AT CSV TO THE UPPER 80S OVER OUR MOST WESTERN COUNTIES. WITH SHOWERS DEPARTING OUR AREA, FROM THE PLATEAU, WE NOW TURN OUR EYES TO THE WEST, WHERE NEW THUNDERSTORMS WERE POPPING UP IN THE AFTERNOON HEAT, OVER SOUTHWESTERN KENTUCKY. THESE STORMS WERE ALSO OCCURRING ALONG THE EDGE OF A BAND OF MID-T0-UPPER LEVEL DRYING THAT EXTENDED FROM SOUTHERN PARTS OF INDIANA AND ILLINOIS, ACROSS SOUTHEAST MISSOURI INTO CENTRAL ARKANSAS. WITH THE POSSIBILITY OF DRY AIR ENTRAINMENT AT THE MID LEVELS, EXPECT SOME GUSTY DOWNBURSTS TO BE POSSIBLE WITH THESE STORMS AS THEY ADVANCE INTO NORTHWESTERN MIDDLE TENNESSEE LATE THIS AFTERNOON AND EVENING. AFTER THE INITIAL CONVECTION THIS EVENING, THAT DEVELOPS MAINLY OVER THE NORTHWEST, BELIEVE WE WILL SEE MORE THUNDERSTORM DEVELOPMENT LATER TONIGHT, AS UPPER TROUGH DEEPENS OVER THE OHIO RIVER VALLEY, ENERGIZING THE SLEEPY STATIONARY FRONT JUST WEST OF PADUCAH, AND BRINGING IT EASTWARD AS A COLD FRONT. EXPECT THE COLD FRONT TO BE NEAR A BWG-BNA-WAYNESBORO LINE BY 12Z FRIDAY, PUSHING TO NR A MSL-LIVINGSTON LINE BY 18Z, AND OFF THE CUMBERLAND PLATEAU BY LATE FRIDAY AFTERNOON. SPC HAS ALL OF OUR AREA IN A SLIGHT RISK FOR SEVERE THUNDERSTORMS THROUGH 12Z FRIDAY, AS THE FRONT PUSHES IN, AND EXPECT TO SEE SIMILAR STORMS TO THE ONES WE HAD THIS MORNING...VERY WET AND JUICY (WITH TORRENTIAL DOWNPOURS) ALONG WITH THE POSSIBILITY FOR STRONG, GUSTY DOWNBURST WINDS. EXPECT SHOWERS AND STORMS TO FINALLY PUSH EAST OF THE MID STATE FRIDAY EVENING, WITH SEVERAL DAYS OF DRY AND AUTUMN-LIKE CONDITIONS TO FOLLOW OVER THE WEEKEND. EXPECT AFTERNOON DEW POINTS IN THE 50S BOTH SATURDAY AND SUNDAY, WITH DAYTIME HIGHS MAINLY IN THE MIDDLE 80S. MANY PLACES WILL LIKELY SEE LOW TEMPERATURES DROP INTO THE MID TO UPPER 50S SUNDAY MORNING. LONG TERM...AFTER OUR DRY SPELL OVER THE WEEKEND, EXPECT NORTHWEST FLOW TO BECOME MORE ZONAL, WITH TWO OR THREE UPPER LEVEL SHORTWAVES LIKELY TO TRAVERSE THE AREA NEXT WEEK. THE TIMING OF THESE IMPULSES, OF COURSE, IS VERY DIFFICULT. IT`S ALSO DIFFICULT TO KNOW HOW MUCH SHRA/TSRA ACTIVITY EACH ONE WITH BRING WITH IT. THEREFORE, HAVE PAINTED POPS WITH A BROAD BRUSH FOR MOST OF NEXT WEEK, WITH A 20% POP MAKING REPEATED ONSTAGE APPEARANCES. TEMPERATURES WILL WARM BACK TO AROUND 90 DEGREES OR IN THE LOWER 90S FOR AREAS WEST OF THE CUMBERLAND PLATEAU, WITH TEMPS FORECAST TO BE MAINLY IN THE MIDDLE 80S ALONG THE PLATEAU ITSELF. && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 31
AREA FORECAST DISCUSSION
NWS MEMPHIS TN
639 PM CDT THU AUG 9 2012 .DISCUSSION... /ISSUED 304 PM CDT THU AUG 9 2012/ SKIES ARE MOSTLY SUNNY THIS AFTERNOON ACROSS MUCH OF THE FORECAST AREA WITH TEMPERATURES RANGING FROM THE MID 80S TO MID 90S. THE AREA OF RAIN THAT WAS OVER PARTS OF NORTH MISSISSIPPI THIS MORNING HAS PUSHED SOUTH. COLD FRONT CURRENTLY EXTENDS FROM EASTERN OHIO THROUGH SOUTHEAST MISSOURI AND INTO THE TEXAS PANHANDLE. A COUPLE OF THUNDERSTORMS HAVE DEVELOPED AHEAD OF THE FRONT OVER WESTERN KENTUCKY AND ARE TRACKING SOUTHEAST TOWARD THE FORECAST AREA. THE COLD FRONT WILL CONTINUE TO TRACK SOUTHEAST TONIGHT WITH SOME ADDITIONAL SCATTERED THUNDERSTORMS EXPECTED TO DEVELOP AHEAD OF THE FRONT. THE FRONT WILL STILL BE OVER NORTH MISSISSIPPI FRIDAY MORNING SO SOME ADDITIONAL SCATTERED THUNDERSTORMS WILL BE POSSIBLE MAINLY OVER AREA SOUTH OF INTERSTATE 40. BEHIND THE FRONT COOLER AND DRIER AIR WILL FILTER INTO THE REGION. TEMPERATURES WILL BE MUCH COOLER WITH HIGHS ONLY IN THE 80S TO AROUND 90. BY FRIDAY NIGHT...THE FRONT WILL BE WELL SOUTH OF THE REGION ENDING THE THREAT OF RAIN. WITH DRIER AIR IN PLACE TEMPERATURES WILL COOL OFF SOME WITH SOME LOCATIONS IN WEST TENNESSEE DROPPING BELOW 60 DEGREES BY SATURDAY MORNING. THE WEEKEND LOOKS TO BE QUITE PLEASANT AS HIGH PRESSURE REMAINS IN PLACE. DRY WEATHER WILL CONTINUE FOR BOTH SATURDAY AND SUNDAY WITH TEMPERATURES MAINLY BELOW NORMAL BOTH DAYS. BY MONDAY...A WEAK COLD FRONT WILL BE APPROACHING THE REGION WITH SOME SCATTERED THUNDERSTORMS POSSIBLE AHEAD OF THE FRONT. THE FRONT WILL CONTINUE TO MOVE SLOWLY SOUTHEAST MONDAY NIGHT AND TUESDAY WITH MORE SCATTERED THUNDERSTORMS POSSIBLE FROM MONDAY NIGHT THROUGH TUESDAY NIGHT. HIGH PRESSURE WILL BRIEFLY BUILD INTO THE REGION ON WEDNESDAY BRINGING A BRIEF END TO THE THREAT OF RAIN. BY WEDNESDAY NIGHT THE COLD FRONT WILL LIFT BACK NORTH AS A WARM FRONT BRINGING A CHANCE OF MORE THUNDERSTORMS FOR WEDNESDAY NIGHT AND MUCH OF THURSDAY. ARS && .AVIATION... 00Z TAF SET COLD FRONT STILL LOCATED BACK TO THE NORTHWEST BUT LOWER DEWPOINTS HAVE WORKED INTO MUCH OF THE CWA THUS BEGINNING TO HAVE DOUBTS ON TSRA DEVELOPMENT THIS EVENING ALONG THE FRONT. LATEST HRRR RUN DOESN/T SHOW ANYTHING DEVELOPING AND THE NEW NAM SHOWS STUFF DEVELOPING NOT UNTIL THE FRONT IS SOUTH AND EAST OF MEMPHIS. FOR NOW WILL REMOVE MENTION OF VCTS AT KJBR BUT WILL LEAVE VCTS WORDING AT OTHER TAF SITES. SOUTHWEST WINDS AROUND 8-10 KTS WITH HIGHER GUSTS AT TIMES EXPECTED AHEAD OF THE FRONT. WINDS WILL SWITCH TO THE NORTHWEST AND EVENTUALLY TO THE NORTH BEHIND THE FRONT. KRM && && .PRELIMINARY POINT TEMPS/POPS... MEM 74 87 67 88 / 30 20 10 0 MKL 69 84 59 86 / 40 20 0 0 JBR 71 87 64 89 / 20 10 0 0 TUP 72 89 65 88 / 40 30 10 0 && .MEG WATCHES/WARNINGS/ADVISORIES... AR...NONE. MO...NONE. MS...NONE. TN...NONE. && $$
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
602 PM CDT THU AUG 9 2012 .UPDATE... NOT IMPRESSED WITH THE CHANCES FOR CONVECTION OVERNIGHT. ONLY BULLISH TRENDS I SEE ARE WITH THE WRF AND THE FROPA WHICH IS EXPECTED AT 12Z. OTW...UPPER DYNAMICS LOOKING WEAK WITH AN OVERALL DECREASE IN MOISTURE DEPTH FROM 00Z TO 06Z. HRRR SHOWS ZILCH THROUGH 6Z AND UPPER DIVERGENCE QUITE WEAK THROUGH 12Z ON THE GFS AND NAM. I WILL GO AHEAD AND UPDATE GRIDS AD KNOCK POPS DOWN PRIOR TO 06Z. AFT 06Z...WILL KEEP THE LIKELY POPS GOING ACROSS THE NORTH BUT THIS MAY NEED A DOWNWARD YANK AS WELL LATER IN THIS SHIFT. REMAINDER OF FCST LOOKS TO BE IN GOOD SHAPE. NO MENTION OF FOG CURRENTLY AND I SEE NO REASON TO ADD ANY AS TOVERS REMAIN NEAR TO ABOVE 0. MIN TEMP FCST LOOKS TO BE IN GOOD SHAPE. UPDATE OUT SHORTLY. && .PREV DISCUSSION... /ISSUED 340 PM CDT THU AUG 9 2012/ SHORT TERM...SHOWERS AND CLOUDS THAT STILL LINGERED ALONG THE CUMBERLAND PLATEAU AT MID-AFTERNOON WERE HELPING TO PRODUCE A SIGNIFICANT TEMPERATURE GRADIENT ACROSS THE MID STATE. AT 300 PM...TEMPERATURES RANGED FROM THE UPPER 60S AT CSV TO THE UPPER 80S OVER OUR MOST WESTERN COUNTIES. WITH SHOWERS DEPARTING OUR AREA, FROM THE PLATEAU, WE NOW TURN OUR EYES TO THE WEST, WHERE NEW THUNDERSTORMS WERE POPPING UP IN THE AFTERNOON HEAT, OVER SOUTHWESTERN KENTUCKY. THESE STORMS WERE ALSO OCCURRING ALONG THE EDGE OF A BAND OF MID-T0-UPPER LEVEL DRYING THAT EXTENDED FROM SOUTHERN PARTS OF INDIANA AND ILLINOIS, ACROSS SOUTHEAST MISSOURI INTO CENTRAL ARKANSAS. WITH THE POSSIBILITY OF DRY AIR ENTRAINMENT AT THE MID LEVELS, EXPECT SOME GUSTY DOWNBURSTS TO BE POSSIBLE WITH THESE STORMS AS THEY ADVANCE INTO NORTHWESTERN MIDDLE TENNESSEE LATE THIS AFTERNOON AND EVENING. AFTER THE INITIAL CONVECTION THIS EVENING, THAT DEVELOPS MAINLY OVER THE NORTHWEST, BELIEVE WE WILL SEE MORE THUNDERSTORM DEVELOPMENT LATER TONIGHT, AS UPPER TROUGH DEEPENS OVER THE OHIO RIVER VALLEY, ENERGIZING THE SLEEPY STATIONARY FRONT JUST WEST OF PADUCAH, AND BRINGING IT EASTWARD AS A COLD FRONT. EXPECT THE COLD FRONT TO BE NEAR A BWG-BNA-WAYNESBORO LINE BY 12Z FRIDAY, PUSHING TO NR A MSL-LIVINGSTON LINE BY 18Z, AND OFF THE CUMBERLAND PLATEAU BY LATE FRIDAY AFTERNOON. SPC HAS ALL OF OUR AREA IN A SLIGHT RISK FOR SEVERE THUNDERSTORMS THROUGH 12Z FRIDAY, AS THE FRONT PUSHES IN, AND EXPECT TO SEE SIMILAR STORMS TO THE ONES WE HAD THIS MORNING...VERY WET AND JUICY (WITH TORRENTIAL DOWNPOURS) ALONG WITH THE POSSIBILITY FOR STRONG, GUSTY DOWNBURST WINDS. EXPECT SHOWERS AND STORMS TO FINALLY PUSH EAST OF THE MID STATE FRIDAY EVENING, WITH SEVERAL DAYS OF DRY AND AUTUMN-LIKE CONDITIONS TO FOLLOW OVER THE WEEKEND. EXPECT AFTERNOON DEW POINTS IN THE 50S BOTH SATURDAY AND SUNDAY, WITH DAYTIME HIGHS MAINLY IN THE MIDDLE 80S. MANY PLACES WILL LIKELY SEE LOW TEMPERATURES DROP INTO THE MID TO UPPER 50S SUNDAY MORNING. LONG TERM...AFTER OUR DRY SPELL OVER THE WEEKEND, EXPECT NORTHWEST FLOW TO BECOME MORE ZONAL, WITH TWO OR THREE UPPER LEVEL SHORTWAVES LIKELY TO TRAVERSE THE AREA NEXT WEEK. THE TIMING OF THESE IMPULSES, OF COURSE, IS VERY DIFFICULT. IT`S ALSO DIFFICULT TO KNOW HOW MUCH SHRA/TSRA ACTIVITY EACH ONE WITH BRING WITH IT. THEREFORE, HAVE PAINTED POPS WITH A BROAD BRUSH FOR MOST OF NEXT WEEK, WITH A 20% POP MAKING REPEATED ONSTAGE APPEARANCES. TEMPERATURES WILL WARM BACK TO AROUND 90 DEGREES OR IN THE LOWER 90S FOR AREAS WEST OF THE CUMBERLAND PLATEAU, WITH TEMPS FORECAST TO BE MAINLY IN THE MIDDLE 80S ALONG THE PLATEAU ITSELF. && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 21
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
359 PM CDT WED AUG 8 2012 .SHORT TERM... SHOWERS AND THUNDERSTORMS ARE DEVELOPING ACROSS THE HEARTLAND AND CONCHO VALLEY THIS AFTERNOON. THIS ACTIVITY IS DEVELOPING IN ASSOCIATION WITH LIFT FROM A WEAK SHORT WAVE THAT IS OVERSPREADING THE AREA FROM THE NORTH. LATEST HRRR SEEMS TO BE DOING A DECENT JOB SO FAR AND INDICATES ADDITIONAL DEVELOPMENT ACROSS THE SOUTHERN HALF OF THE FORECAST AREA THROUGH EARLY EVENING. WILL MAINTAIN 30 POPS SOUTH AND SLIGHT CHANCE POPS NORTH ACROSS THE BIG COUNTRY THROUGH THE EVENING HOURS. MAY STILL SEE SOME LINGERING ACTIVITY ALONG THE I-10 CORRIDOR THROUGH LATE EVENING BUT MOST OF THE CONVECTION SHOULD DISSIPATE AFTER SUNEST. THE MAIN THREAT FROM THUNDERSTORMS WILL BE LOCALLY HEAVY RAINFALL...GUSTY WINDS AND DANGEROUS CLOUD TO GROUND LIGHTNING. DRIER AIR WILL FILTER INTO THE AREA FROM THE NORTH LATER TONIGHT AND THURSDAY. THIS WILL RESULT IN DRY AND HOT CONDITIONS ACROSS THE AREA WITH AFTERNOON HIGHS AROUND THE CENTURY MARK. CANNOT RULE OUT AN ISOLATED STORM OR TWO ACROSS SOUTHEAST SECTIONS THURSDAY AFTERNOON SO KEPT ISOLATED MENTION OVER THIS AREA. .LONG TERM... AS AN UPPER TROUGH AND LOW DROP SOUTHEAST ACROSS THE LOWER GREAT LAKES REGION...TRAILING PORTION OF ASSOCIATED COLD FRONT WILL MOVE SOUTH INTO THE BIG COUNTRY THURSDAY NIGHT... AND ACROSS THE REST OF WEST CENTRAL TEXAS ON FRIDAY. THIS PORTION OF THE FRONT WILL BE WEAK HOWEVER...WITH THE MAIN ADVECTION OF COOLER AIR EXPECTED TO BE TO THE NORTHEAST OF OUR AREA. WITH WEAK SURFACE CONVERGENCE AND A DRIER AIRMASS PROGGED...RAIN CHANCES LOOK LOOK TOO SMALL INCLUDE IN OUR AREA WITH THE ARRIVAL/PASSAGE OF THIS FRONT. TEMPERATURES WILL BE SLIGHTLY COOLER ACROSS THE BIG COUNTRY...WHERE HIGHS FRIDAY ARE EXPECTED TO BE IN THE MID/UPPER 90S. THE UPPER HIGH WILL BE CENTERED OVER NEW MEXICO DURING THE WEEKEND. GIVEN ITS PROXIMITY...HOT AND DRY CONDITIONS CAN BE EXPECTED FOR WEST CENTRAL TEXAS. THE WARMEST READINGS ARE EXPECTED SUNDAY...WHEN HIGHS SHOULD RANGE FROM 100-105 DEGREES AREAWIDE. LITTLE CHANGE IS INDICATED WITH THIS PATTERN THROUGH AT LEAST EARLY NEXT WEEK. THE 12Z GFS AND ECMWF SHOW A WEAKENING WITH THIS HIGH BY NEXT TUESDAY OR WEDNESDAY...WITH THE GFS BRINGING A DISTURBANCE NORTH-NORTHEAST FROM THE LOWER RIO GRANDE VALLEY INTO CENTRAL AND EASTERN TEXAS. GIVEN THAT THIS IS LATE DAY 6 AND DAY 7...LEANING AT THIS TIME TOWARD PERSISTENCE WITH THE FORECAST. && .PRELIMINARY POINT TEMPS/POPS... ABILENE 74 101 72 97 70 / 20 10 10 5 5 SAN ANGELO 74 101 73 101 70 / 30 20 10 10 5 JUNCTION 73 97 72 101 70 / 30 20 10 10 5 && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 24/19
AREA FORECAST DISCUSSION...UPDATED
NWS SAN ANGELO TX
212 PM CDT WED AUG 8 2012 .UPDATE... MADE A QUICK UPDATE TO THE FORECAST FOR THIS AFTERNOON AND EVENING TO INCREASE POPS TO 30 PERCENT ACROSS THE SOUTHERN HALF OF THE FORECAST AREA. && .DISCUSSION... SEVERAL WEAK OUTFLOW BOUNDARIES LEFT OVER FROM LAST NIGHT WILL LINGER ACROSS THE AREA AND WILL BE A FOCUS FOR CONVECTIVE DEVELOPMENT THIS AFTERNOON. LIFT WILL ALSO INCREASE ACROSS THE AREA THIS AFTERNOON AS A WEAK SHORT WAVE DROPS SOUTH FROM NORTHWEST TEXAS. LATEST HRRR SHOWS CONVECTION DEVELOPING ACROSS THE HEARTLAND AND CONCHO VALLEY BY 20Z AND ALREADY STARTING TO SEE SOME NEW CELLS DEVELOP OVER BROWN AND COLEMAN COUNTIES. LATEST NAM/RUC ALSO INDICATING CONVECTIVE DEVELOPMENT IN A SIMILAR FASHION. CONFIDENCE HAS INCREASED TO RAISE POPS TO 30 PERCENT ACROSS THE SOUTHERN TWO THIRDS OF THE CWA THROUGH THE EVENING HOURS....WITH CONVECTION DIMINISHING LATER THIS EVENING. UPDATED PRODUCTS WERE SENT. && .PREV DISCUSSION... /ISSUED 1255 PM CDT WED AUG 8 2012/ DISCUSSION... SEE 18Z AVIATION DISCUSSION BELOW. AVIATION... MAIN CHALLENGE THIS FORECAST CYCLE WILL BE CONVECTIVE CHANCES ACROSS THE SOUTHERN TAF SITES THIS AFTERNOON. EXPECT PREDOMINANTLY VFR FOR THE TERMINALS THE NEXT 24 HOURS BUT SCATTERED CONVECTION IS EXPECTED TO DEVELOP MAINLY SOUTH OF THE KABI TERMINAL AFTER 20Z. INCLUDED VCTS FOR ALL TERMINALS EXCEPT KABI THIS AFTERNOON UNTIL 01Z. VISIBILITY AND CIGS WILL BE LOWER WITH ANY CONVECTION THAT OCCURS AND WILL MAKE NECESSARY AMENDMENTS IF NEEDED. LIGHT WINDS WILL CONTINUE THE NEXT 24 HOURS WITH SPEEDS AT OR BELOW 10 KT. PREV DISCUSSION... /ISSUED 623 AM CDT WED AUG 8 2012/ DISCUSSION... AVIATION DISCUSSION FOLLOWS. AVIATION... ISOLATED SHOWERS AND THUNDERSTORMS MAY THREATEN THE KABI... KSJT...AND KBBD TERMINALS THROUGH TODAY. A NIGHT TIME COMPLEX OF STORMS MAY APPROACH THE KABI TERMINAL TONIGHT AFTER MIDNIGHT AND BRING GUSTY NORTH WINDS OF 30 TO 40KTS. STRONG DOWNBURST WINDS IN EXCESS OF 45KTS MIGHT ACCOMPANY ANY OF THE STORMS THAT DEVELOP THIS AFTERNOON AND EVENING. HAVE LEFT OUT MENTION OF WINDS AND TSTORMS IN TAF BECAUSE OF THEIR ISOLATED NATURE. SATELLITE SHOWS A MESOSCALE CONVECTIVE VORTEX NEAR HASKELL THAT WAS SLIDING SOUTH AND WAS PRODUCING A FEW SHOWERS. SHOWERS OR THUNDERSTORMS COULD FORM NEAR THIS FEATURE AS IT TRACKS SOUTH. PREV DISCUSSION... /ISSUED 338 AM CDT WED AUG 8 2012/ SHORT TERM... IMPACTS...GUSTY NORTH WINDS 20 TO 25 MPH...AND ISOLATED LIGHTNING STRIKES THROUGH 9 AM NORTH OF A LINE FROM MARY NEAL TO CROSS PLAINS. ISOLATED DAMAGING WIND GUSTS AND CLOUD TO GROUND LIGHTNING STRIKES THIS AFTERNOON ANYWHERE IN WEST CENTRAL TEXAS. GUSTY NORTH WINDS OF 35 TO 45 MPH AGAIN TONIGHT MAINLY NORTH OF I20. HOT TEMPERATURES ABOVE 100 ACROSS A LARGE PART OF THE WEST CENTRAL TEXAS. DISCUSSION...AT 08Z...THE LEADING EDGE OF AN OUTFLOW BOUNDARY STRETCHED FROM ROBY TO ANSON TO ALBANY AND WAS MOVING SOUTH NEAR 30 MPH. BASED ON THE WEST TEXAS MESONET DATA...WIND GUSTED TO NEAR 39 MPH AT HASKELL AT 0720Z. MOSTLY SHOWERS AND AN ISOLATED THUNDERSTORM CONTINUED TO DEVELOP BEHIND THE BOUNDARY. THE DIURNAL LOW LEVEL JET OF 25 TO 30 KTS ALONG WITH HIGHER DIURNAL CAPE VALUES NEAR 1000 J/KG WERE SUSTAINING THESE STORMS BEHIND THE BOUNDARY. DECIDED TO GO WITH THE HIGHEST POPS NEAR 25 PERCENT ALONG AND NORTH OF INTERSTATE 20 AND THEN 20 POPS SOUTH OF I20. THIS COMPLEX OF STORMS SHOULD CONTINUE BEFORE DIMINISHING AROUND 900 AM AS THE LOW LEVEL JET WEAKENS. THE AFOREMENTIONED OUTFLOW BOUNDARY MAY ALSO SERVE AS A TRIGGER FOR THUNDERSTORMS TO FORM THIS AFTERNOON. CONTINUED 20 POPS FOR MOST OF THE AREA TODAY. WENT WITH HOTTEST TEMPERATURES ACROSS THE SOUTH AND SLIGHTLY COOLER IN THE RAIN COOLED AIR TO THE NORTH. EXPECT A REPEAT PERFORMANCE LATE TONIGHT AS SHOWERS AND THUNDERSTORMS DEVELOP IN THE NORTHWEST FLOW ACROSS THE TEXAS PANHANDLE AND THEN MOVE SOUTH DURING THE NIGHT. FOR TONIGHT...WENT WITH CHC POPS ACROSS THE BIG COUNTRY AND 20 POPS SOUTH. LONG TERM... MODELS HAVE THE 500MB HIGH CENTERED OVER THE FOUR CORNERS AREA THURSDAY MORNING WITH THE NAM MOVING A SHORT WAVE DISTURBANCE EMBEDDED IN THE NORTHERN FLOW ALOFT SOUTH THROUGH THE FORECAST AREA DURING THE ON THURSDAY. THE NAM THEN MOVES A WEAK COLD FRONT THROUGH THE AREA DURING THE DAY ON FRIDAY. THE GFS BRINGS THE COLD FRONT THROUGH THE CWA EARLIER...DURING THE DAY ON THURSDAY. WILL CONTINUE THE SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS DURING THE DAY ON THURSDAY AND INTO THURSDAY EVENING. SHOULD SEE FRIDAY AND SATURDAY AFTERNOON HIGHS A DEGREE OR TWO COOLER IN THE WAKE OF THE COLD FRONT. THE UPPER HIGH WILL BUILD EAST FOR THE REMAINDER OF THE EXTENDED WITH AFTERNOON HIGHS WARMING A FEW DEGREES BEGINNING SUNDAY. WITH THE EXPANDING UPPER RIDGE OVER THE FORECAST...THE OUTLOOK THROUGH THE REMAINDER OF THE EXTENDED WILL BE HOT AN DRY. && .PRELIMINARY POINT TEMPS/POPS... ABILENE 99 75 100 72 97 / 20 20 10 10 5 SAN ANGELO 101 75 102 73 101 / 30 30 20 20 10 JUNCTION 102 74 103 72 101 / 20 30 20 20 10 && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 99/99
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
100 PM EDT WED AUG 8 2012 .SYNOPSIS... A STATIONARY FRONT ACROSS THE MOUNTAINS WILL GRADUALLY DISSIPATE TODAY AS WEAK HIGH PRESSURE SLIDES EAST INTO THE REGION BY TONIGHT BEFORE WEAKENING ON THURSDAY. A STRONG COLD FRONT WILL SWEEP ACROSS THE REGION FRIDAY INTO FRIDAY EVENING...BRINGING ANOTHER ROUND OF SHOWERS AND STORMS...SOME POTENTIALLY STRONG. COOLER AND DRIER WEATHER IS EXPECTED BEHIND THE FRONT OVER THE WEEKEND INTO EARLY NEXT WEEK AS HIGH PRESSURE BUILDS INTO THE REGION. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1255 PM ED WEDNESDAY... ISOALTED TO SCATTERED SHOWERS AND STORMS HAVE DEVELOPED OVER THE PAST 30 MINUTES GENERALLY ALONG AND EAST OF A LINE FROM WILKES COUNTY NC TO APPOMATTOX COUNTY VA. ANTICIPATE THIS AREA TO BE THE FOCUS FOR ADDITIONAL SHOWERS AND STORMS AS THE AFTERNOON PROGRESSES. CANNOT RULE OUT VERY ISOLATED COVERAGE WEST OF THIS REGION. HAVE MADE ADJUSTMENTS TO THE HOURLY TEMPERATURE...DEW POINT...WINDS AND SKY COVER BASED UPON THE CURRENT OBSERVATIONS AND EXPECTED TRENDS THIS AFTERNOON. THIS PROMPTED AN INCREASE IN THE FORECAST HIGH TEMPERATURES BY TWO TO THREE DEGREES ACROSS THE VIRGINIA PIEDMONT. AS OF 952 AM EDT WEDNESDAY... SURFACE OBSERVATIONS AND VISIBLE SATELLITE IMAGERY INDICATES A FEW POCKETS OF LINGERING FOG IN SOME OF THE MOUNTAIN VALLEYS. HOWEVER...ANTICIPATE THAT BY 1100 AM EDT...MOST OR ALL OF THIS LINGERING FOG WILL HAVE DISSIPATED. PRECIPITATION HAS BEEN LIMITED TO JUST A FEW ISOLATED SHOWERS ACROSS PARTS OF BUCKINGHAM COUNTY VIRGINIA. ANTICIPATE LIMITED...IF ANY COVERAGE...THROUGH NOON BEFORE COVERAGE INCREASES NEAR THE NC/VA BORDER. NO OTHER SIGNIFICANT CHANGES. THE HOURLY TEMPERATURE...DEW POINT...WIND AND SKY COVER GRIDS HAVE BEEN TWEAKED TO REFLECT THE LATEST OBSERVATIONS AND EXPECTED TRENDS INTO THE EARLY AFTERNOON. AS OF 230 AM EDT WEDNESDAY... WEAK SURFACE BOUNDARY ACROSS THE MOUNTAINS WILL GRADUALLY FADE TODAY AS A MID LEVEL WAVE PASSES TO THE EAST BY AFTERNOON AND DRIER AIR ALOFT PER VAPOR LOOP ADVECTS IN FROM THE NW. HOWEVER THE LOW LEVELS WILL REMAIN RATHER MOIST AND GIVEN ANOTHER SUBTLE S/W PUSHING ACROSS THE WEST LATER ON CANT TOTALLY RULE OUT ADDED ISOLATED CONVECTION...ESPCLY BLUE RIDGE AND POINTS EAST...MAINLY SOUTH OF HIGHWAY 460 WHERE BOUNDARY LAYER MOISTURE/INSTABILITY WILL BE BETTER. LATEST LOCAL GUIDANCE AS WELL AS THE SPC WRF AND GFS HINT AT THIS WITH A FEW TSRA CLUSTERS DEVELOPING SW SECTIONS ALONG THE BLUE RIDGE PER DIFF HEATING UNDER WEAK THETA-E RIDGING...AND THEN OUT EAST JUST AHEAD OF WHAT WAS LEFT OF THE OLD FRONT. AGAIN GIVEN WEAK STEERING AND LOCAL CONVERGENCE/OUTFLOW COULD ALLOW FOR STORMS TO POP UP AND DUMP HEAVY RAINFALL BUT NOT THINKING MUCH MORE COVERAGE THAN CHANCE TO ISOLATED POPS TODAY. OTRW EXPECTING A GRADUAL RETURN TO MORE SUNSHINE AS THE HIGH/MID LEVEL CLOUD DECK ERODES AND SHIFTS NE WITH THE PASSAGE OF THE WAVE TO THE EAST THIS MORNING. THINK CLOUDS WILL LIMIT FOG FROM BECOMING TOO WIDESPREAD EXCEPT PERHAPS THE FAR WEST SO WILL KEEP MENTION PENDING RELEASE COVERAGE. WARM START AND SLIGHT 85H WARMING UNDER A WEAK WEST/NW TRAJECTORY ALOFT SHOULD PUSH TEMPS TO AROUND 90 EAST AND WELL INTO THE 80S WEST SO BUMPED UP CLOSER TO THE MAV VALUES TODAY. ANY CONVECTION SHOULD QUICKLY FADE WITH LOSS OF HEATING THIS EVENING GIVEN LACK OF SUPPORT...WITH MAINLY CLEAR SKIES AFTER MIDNIGHT AS WE SLIDE IN BETWEEN THE DEEP MOISTURE LOBE TO THE SE AND THE NEXT UPSTREAM 5H TROF. THUS WILL CARRY SOME ISOLATED EVENING POPS MAINLY SOUTH/EAST THEN GO DRY WITH PERHAPS SOME PATCHY FOG UNDER WEAK HIGH PRESSURE LATE. THIS SHOULD ALSO ALLOW LOW TEMPS TO DROP CLOSER TO THE COOLER MAV FOR THE MOST PART WITH RANGE FROM AROUND 60 VALLEYS TO UPPER 60S SE AND RIDGES. && .SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/... AS OF 430 AM EDT WEDNESDAY... ACTIVE WEATHER WILL BEGIN THE SHORT TERM PERIODS AS THE UPPER FLOW AMPLIFIES ACROSS THE U.S...FEATURING A DEEPENING NEGATIVELY TILTED UPPER TROUGH FROM THE GREAT LAKES TOWARD THE MID-ATLANTIC THU-FRI. THE POPS AND SEVERE THREAT FOR THU SOMEWHAT QUESTIONABLE...BUT A MORE DEFINITE POSSIBILITY FOR FRI AS THE ENTIRE SYSTEM SHIFTS ACROSS THE CWA. NORMALLY SUCH A PATTERN WOULD SUGGEST A HIGH THREAT OF SEVERE WX ACROSS THE REGION...ESPECIALLY FRI. HOWEVER...EXTENSIVE CLOUD COVER AND MORNING SHRA FRI WILL LIKELY LIMIT HEATING...WITH THE GREATER LIKELIHOOD FOR SEVERE PROBABLY FOCUSED ACROSS THE PIEDMONT AND TOWARD THE COASTAL PLAIN FRI AFTERNOON/EVENING. AT THIS POINT...HAVE ONLY MENTIONED GUSTY WINDS AND LOCALLY HEAVY RAIN. SPC HAS OUTLOOKED THE WESTERN SECTIONS ON DAY2 AND THE ENTIRE CWA ON DAY3...BUT AGAIN FEEL MAIN THREAT ON DAY3 SHOULD BE EAST OF THE BLUE RIDGE. MODEL AND HPC QPF NOT OVERLY IMPRESSIVE AND INDICATIVE OF A SKIP OVER EFFECT OF THE HEAVIEST PRECIPITATION AS AFOREMENTIONED TOWARD EASTERN VA/NC. NONETHELESS...WITH FAIRLY WIDESPREAD HEAVY RAIN ACROSS THE MOUNTAIN AREAS DURING THE PAST COUPLE OF WEEKS...LATER SHIFTS WILL NEED TO EVALUATE THE ISSUANCE OF AN FFA WEST OF THE BLUE RIDGE WHERE 1HR FFG VALUES GENERALLY LESS THAN 2 INCHES. WITH REFERENCE TO POP TIMING...ENOUGH FORCING APPEARS EVIDENT COMBINED WITH PRE-SYSTEM HEATING TO SUPPORT GOOD CHC POPS EAST TO LIKELY POPS WEST BY FRI EVENING. WILL HAVE LIKELY POPS TO ALL AREAS FRI...WHICH MAY WELL BECOME CATEGORICAL WITH LATER FORECASTS. 850MB TEMPS NEAR +20C ACROSS THE PIEDMONT REGION THU WILL STILL SUPPORT WELL ABOVE NORMAL TEMPS IN THE LOW TO MID 90S EAST OF THE BLUE RIDGE...WITH MOSTLY 80S TO THE WEST...EXCEPT 70S IN THE MOUNTAINS ABOVE 3000 FT. EXTENSIVE CLOUD COVER AND SHRA/TSRA FRI SHOULD HOLD TEMPS TO THE 70S IN THE MOUNTAINS TO 80S EAST OF THE BLUE RIDGE. LATEST MODELS HAVE COME INTO BETTER AGREEMENT IN PUSHING THE MAIN UPPER TROUGH EAST OF THE REGION BY EARLY SAT...WHICH SHOULD TAKE THE BULK OF THE PCPN WITH IT. HOWEVER...THE PARENT...RATHER DEEP UPPER LOW FOR MID-AUGUST...WILL SWEEP THROUGH CENTRAL PA SAT AND COULD PROMOTE ENOUGH LIFT IN UPSLOPE AREAS OF WV/N VA TO SUPPORT ISOLD -SHRA DURING DAYTIME HEATING...THUS HAVE INCLUDED SLIGHT CHC POPS ACCORDINGLY. 850MB TEMPS DROP TO THE LOWEST LEVELS SEEN IN OVER TWO MONTHS...WITH +10C ACROSS ALL EXCEPT THE PIEDMONT BY 12Z SAT. THIS SHOULD ALLOW FOR SOME RATHER REFRESHING HIGHS IN THE 70S WEST OF THE BLUE RIDGE AND 80S EAST...WITH DEWPOINTS DROPPING INTO THE 50S WEST OF THE BLUE RIDGE AND 60S ACROSS THE PIEDMONT. && .LONG TERM /SUNDAY THROUGH TUESDAY/... AS OF 430 AM EDT WEDNESDAY... HAVE NOT MADE ANY SIGNIFICANT CHANGES TO THE LONG TERM AT THIS TIME. IT APPEARS THAT A RATHER UNSETTLED WEATHER PATTERN WILL REMAIN IN PLACE THROUGHOUT THE EXTENDED AS A SERIES OF NW FLOW DISTURBANCES TRACK ACROSS THE REGION. THE ECMWF/GFS ARE AT ODDS WITH RESPECT TO THE AMPLIFICATION OF THE NEXT UPPER TROUGH TOWARD THE MIDDLE OF NEXT WEEK... WITH THE GFS FAVORING A FLATTER...MORE ZONAL FLOW. AT ANY RATE...IT APPEARS THAT AT LEAST CHC POPS FOR SHRA/TSRA WILL CONTINUE THROUGHOUT THE EXTENDED WITH TEMPS RETURNING BACK TO AOA NORMAL LEVELS. LOW-LEVEL MOISTURE WILL ALSO BE INCREASING...RESULTING IN INCREASINGLY MORE HUMID CONDITIONS AS WELL. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... AS OF 645 AM EDT WEDNESDAY... EXTENSIVE MID AND HIGH CLOUD CANOPY ASSOCIATED WITH WAVE/UPPER JET CONTINUES TO SLOWLY PUSH EAST AND SHOULD EXIT THE AREA BY MID MORNING IF NOT SOONER. MAY SEE A FEW ADDED SHRA DEVELOP OVER THE SW THIS MORNING BUT MOSTLY SOUTH OF THE TAF SITES. OTRW FOG THE MAIN CONCERN AGAIN EARLY THIS MORNING WITH AREAS OF IFR/LIFR IN THE VALLEYS/ALONG THE WESTERN RIDGES...PRIMARILY KLWB/KBLF AND KBCB IN THE WEST AND KLYH IN THE EAST. MAY STILL SEE A BRIEF PERIOD OF MVFR IN FOG AT KDAN OTRW VFR AROUND KROA. SHOULD SEE MOST OF THE FOG/STRATUS ERODE BY 14Z...10AM WITH ONLY KLWB LIKELY HANGING ONTO POCKETS OF LOWER VSBYS A WHILE LONGER. ONCE THE FOG FADES AND THE MID DECK EXITS SHOULD SEE MAINLY VFR FOR MOST OF THE DAY WITH SCTD-BKN 4-6K FT CU FIELDS. ISOLATED CONVECTION AGAIN POSSIBLE ESPCLY IN SPOTS ALONG THE BLUE RIDGE AND OUT EAST SO INCLUDED A VCTS MENTION FROM KROA EAST BASED ON THE LATEST HRRR MODEL WHICH SHOWS A FEW CLUSTERS DEVELOPING FROM NW NC INTO THE VA PIEDMONT BY MID AFTERNOON. ELSW WILL LEAVE OUT FOR NOW GIVEN ISOLATED NATURE. AGAIN EXPECT ANY STORMS TO DIMINISH WITH LOSS OF HEATING FOLLOWED BY MAINLY CLEAR SKIES WITH ANOTHER ROUND OF MVFR/IFR FOG ESPCLY VALLEYS GIVEN LESS CLOUD COVER OVERNIGHT. PROXIMITY OF THE OLD FRONT AND TROPICAL AIRMASS JUST TO THE SOUTH... WHICH WILL BEGIN A NORTHWARD RETURN BY LATE WEEK...WILL MAINTAIN A DAILY THREAT FOR PATCHY FLIGHT RESTRICTIONS IN VICINITY OF MAINLY DIURNALLY DRIVEN SHOWERS/STORMS FOR MUCH OF THE REST OF THE WEEK...WITH A CONTINUED THREAT FOR RESTRICTIONS INTO THE OVERNIGHT PERIODS WHERE FOG DEVELOPS. MORE WIDESPREAD SHRA/TSRA LIKELY BY WEEKS END AHEAD OF A STRONGER COLD FRONT THAT LOOKS TO DIVE THRU THE REGION FRIDAY INTO FRIDAY NIGHT. IMPROVING CONDITIONS TO VFR LIKELY BEHIND THE FRONT ESPCLY ACROSS THE EAST FOR THE WEEKEND. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...JH NEAR TERM...DS/JH SHORT TERM...RAB LONG TERM...PH/RAB AVIATION...DS/JH/KM
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
957 AM EDT WED AUG 8 2012 .SYNOPSIS... A STATIONARY FRONT ACROSS THE MOUNTAINS WILL GRADUALLY DISSIPATE TODAY AS WEAK HIGH PRESSURE SLIDES EAST INTO THE REGION BY TONIGHT BEFORE WEAKENING ON THURSDAY. A STRONG COLD FRONT WILL SWEEP ACROSS THE REGION FRIDAY INTO FRIDAY EVENING...BRINGING ANOTHER ROUND OF SHOWERS AND STORMS...SOME POTENTIALLY STRONG. COOLER AND DRIER WEATHER IS EXPECTED BEHIND THE FRONT OVER THE WEEKEND INTO EARLY NEXT WEEK AS HIGH PRESSURE BUILDS INTO THE REGION. && .NEAR TERM /THROUGH TONIGHT/... AS OF 952 AM EDT WEDNESDAY... SURFACE OBSERVATIONS AND VISIBLE SATELLITE IMAGERY INDICATES A FEW POCKETS OF LINGERING FOG IN SOME OF THE MOUNTAIN VALLEYS. HOWEVER...ANTICIPATE THAT BY 1100 AM EDT...MOST OR ALL OF THIS LINGERING FOG WILL HAVE DISSIPATED. PRECIPITATION HAS BEEN LIMITED TO JUST A FEW ISOLATED SHOWERS ACROSS PARTS OF BUCKINGHAM COUNTY VIRGINIA. ANTICIPATE LIMITED...IF ANY COVERAGE...THROUGH NOON BEFORE COVERAGE INCREASES NEAR THE NC/VA BORDER. NO OTHER SIGNIFICANT CHANGES. THE HOURLY TEMPERATURE...DEW POINT...WIND AND SKY COVER GRIDS HAVE BEEN TWEAKED TO REFLECT THE LATEST OBSERVATIONS AND EXPECTED TRENDS INTO THE EARLY AFTERNOON. AS OF 230 AM EDT WEDNESDAY... WEAK SURFACE BOUNDARY ACROSS THE MOUNTAINS WILL GRADUALLY FADE TODAY AS A MID LEVEL WAVE PASSES TO THE EAST BY AFTERNOON AND DRIER AIR ALOFT PER VAPOR LOOP ADVECTS IN FROM THE NW. HOWEVER THE LOW LEVELS WILL REMAIN RATHER MOIST AND GIVEN ANOTHER SUBTLE S/W PUSHING ACROSS THE WEST LATER ON CANT TOTALLY RULE OUT ADDED ISOLATED CONVECTION...ESPCLY BLUE RIDGE AND POINTS EAST...MAINLY SOUTH OF HIGHWAY 460 WHERE BOUNDARY LAYER MOISTURE/INSTABILITY WILL BE BETTER. LATEST LOCAL GUIDANCE AS WELL AS THE SPC WRF AND GFS HINT AT THIS WITH A FEW TSRA CLUSTERS DEVELOPING SW SECTIONS ALONG THE BLUE RIDGE PER DIFF HEATING UNDER WEAK THETA-E RIDGING...AND THEN OUT EAST JUST AHEAD OF WHAT WAS LEFT OF THE OLD FRONT. AGAIN GIVEN WEAK STEERING AND LOCAL CONVERGENCE/OUTFLOW COULD ALLOW FOR STORMS TO POP UP AND DUMP HEAVY RAINFALL BUT NOT THINKING MUCH MORE COVERAGE THAN CHANCE TO ISOLATED POPS TODAY. OTRW EXPECTING A GRADUAL RETURN TO MORE SUNSHINE AS THE HIGH/MID LEVEL CLOUD DECK ERODES AND SHIFTS NE WITH THE PASSAGE OF THE WAVE TO THE EAST THIS MORNING. THINK CLOUDS WILL LIMIT FOG FROM BECOMING TOO WIDESPREAD EXCEPT PERHAPS THE FAR WEST SO WILL KEEP MENTION PENDING RELEASE COVERAGE. WARM START AND SLIGHT 85H WARMING UNDER A WEAK WEST/NW TRAJECTORY ALOFT SHOULD PUSH TEMPS TO AROUND 90 EAST AND WELL INTO THE 80S WEST SO BUMPED UP CLOSER TO THE MAV VALUES TODAY. ANY CONVECTION SHOULD QUICKLY FADE WITH LOSS OF HEATING THIS EVENING GIVEN LACK OF SUPPORT...WITH MAINLY CLEAR SKIES AFTER MIDNIGHT AS WE SLIDE IN BETWEEN THE DEEP MOISTURE LOBE TO THE SE AND THE NEXT UPSTREAM 5H TROF. THUS WILL CARRY SOME ISOLATED EVENING POPS MAINLY SOUTH/EAST THEN GO DRY WITH PERHAPS SOME PATCHY FOG UNDER WEAK HIGH PRESSURE LATE. THIS SHOULD ALSO ALLOW LOW TEMPS TO DROP CLOSER TO THE COOLER MAV FOR THE MOST PART WITH RANGE FROM AROUND 60 VALLEYS TO UPPER 60S SE AND RIDGES. && .SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/... AS OF 430 AM EDT WEDNESDAY... ACTIVE WEATHER WILL BEGIN THE SHORT TERM PERIODS AS THE UPPER FLOW AMPLIFIES ACROSS THE U.S...FEATURING A DEEPENING NEGATIVELY TILTED UPPER TROUGH FROM THE GREAT LAKES TOWARD THE MID-ATLANTIC THU-FRI. THE POPS AND SEVERE THREAT FOR THU SOMEWHAT QUESTIONABLE...BUT A MORE DEFINITE POSSIBILITY FOR FRI AS THE ENTIRE SYSTEM SHIFTS ACROSS THE CWA. NORMALLY SUCH A PATTERN WOULD SUGGEST A HIGH THREAT OF SEVERE WX ACROSS THE REGION...ESPECIALLY FRI. HOWEVER...EXTENSIVE CLOUD COVER AND MORNING SHRA FRI WILL LIKELY LIMIT HEATING...WITH THE GREATER LIKELIHOOD FOR SEVERE PROBABLY FOCUSED ACROSS THE PIEDMONT AND TOWARD THE COASTAL PLAIN FRI AFTERNOON/EVENING. AT THIS POINT...HAVE ONLY MENTIONED GUSTY WINDS AND LOCALLY HEAVY RAIN. SPC HAS OUTLOOKED THE WESTERN SECTIONS ON DAY2 AND THE ENTIRE CWA ON DAY3...BUT AGAIN FEEL MAIN THREAT ON DAY3 SHOULD BE EAST OF THE BLUE RIDGE. MODEL AND HPC QPF NOT OVERLY IMPRESSIVE AND INDICATIVE OF A SKIP OVER EFFECT OF THE HEAVIEST PRECIPITATION AS AFOREMENTIONED TOWARD EASTERN VA/NC. NONETHELESS...WITH FAIRLY WIDESPREAD HEAVY RAIN ACROSS THE MOUNTAIN AREAS DURING THE PAST COUPLE OF WEEKS...LATER SHIFTS WILL NEED TO EVALUATE THE ISSUANCE OF AN FFA WEST OF THE BLUE RIDGE WHERE 1HR FFG VALUES GENERALLY LESS THAN 2 INCHES. WITH REFERENCE TO POP TIMING...ENOUGH FORCING APPEARS EVIDENT COMBINED WITH PRE-SYSTEM HEATING TO SUPPORT GOOD CHC POPS EAST TO LIKELY POPS WEST BY FRI EVENING. WILL HAVE LIKELY POPS TO ALL AREAS FRI...WHICH MAY WELL BECOME CATEGORICAL WITH LATER FORECASTS. 850MB TEMPS NEAR +20C ACROSS THE PIEDMONT REGION THU WILL STILL SUPPORT WELL ABOVE NORMAL TEMPS IN THE LOW TO MID 90S EAST OF THE BLUE RIDGE...WITH MOSTLY 80S TO THE WEST...EXCEPT 70S IN THE MOUNTAINS ABOVE 3000 FT. EXTENSIVE CLOUD COVER AND SHRA/TSRA FRI SHOULD HOLD TEMPS TO THE 70S IN THE MOUNTAINS TO 80S EAST OF THE BLUE RIDGE. LATEST MODELS HAVE COME INTO BETTER AGREEMENT IN PUSHING THE MAIN UPPER TROUGH EAST OF THE REGION BY EARLY SAT...WHICH SHOULD TAKE THE BULK OF THE PCPN WITH IT. HOWEVER...THE PARENT...RATHER DEEP UPPER LOW FOR MID-AUGUST...WILL SWEEP THROUGH CENTRAL PA SAT AND COULD PROMOTE ENOUGH LIFT IN UPSLOPE AREAS OF WV/N VA TO SUPPORT ISOLD -SHRA DURING DAYTIME HEATING...THUS HAVE INCLUDED SLIGHT CHC POPS ACCORDINGLY. 850MB TEMPS DROP TO THE LOWEST LEVELS SEEN IN OVER TWO MONTHS...WITH +10C ACROSS ALL EXCEPT THE PIEDMONT BY 12Z SAT. THIS SHOULD ALLOW FOR SOME RATHER REFRESHING HIGHS IN THE 70S WEST OF THE BLUE RIDGE AND 80S EAST...WITH DEWPOINTS DROPPING INTO THE 50S WEST OF THE BLUE RIDGE AND 60S ACROSS THE PIEDMONT. && .LONG TERM /SUNDAY THROUGH TUESDAY/... AS OF 430 AM EDT WEDNESDAY... HAVE NOT MADE ANY SIGNIFICANT CHANGES TO THE LONG TERM AT THIS TIME. IT APPEARS THAT A RATHER UNSETTLED WEATHER PATTERN WILL REMAIN IN PLACE THROUGHOUT THE EXTENDED AS A SERIES OF NW FLOW DISTURBANCES TRACK ACROSS THE REGION. THE ECMWF/GFS ARE AT ODDS WITH RESPECT TO THE AMPLIFICATION OF THE NEXT UPPER TROUGH TOWARD THE MIDDLE OF NEXT WEEK... WITH THE GFS FAVORING A FLATTER...MORE ZONAL FLOW. AT ANY RATE...IT APPEARS THAT AT LEAST CHC POPS FOR SHRA/TSRA WILL CONTINUE THROUGHOUT THE EXTENDED WITH TEMPS RETURNING BACK TO AOA NORMAL LEVELS. LOW-LEVEL MOISTURE WILL ALSO BE INCREASING...RESULTING IN INCREASINGLY MORE HUMID CONDITIONS AS WELL. && .AVIATION /14Z WEDNESDAY THROUGH SUNDAY/... AS OF 645 AM EDT WEDNESDAY... EXTENSIVE MID AND HIGH CLOUD CANOPY ASSOCIATED WITH WAVE/UPPER JET CONTINUES TO SLOWLY PUSH EAST AND SHOULD EXIT THE AREA BY MID MORNING IF NOT SOONER. MAY SEE A FEW ADDED SHRA DEVELOP OVER THE SW THIS MORNING BUT MOSTLY SOUTH OF THE TAF SITES. OTRW FOG THE MAIN CONCERN AGAIN EARLY THIS MORNING WITH AREAS OF IFR/LIFR IN THE VALLEYS/ALONG THE WESTERN RIDGES...PRIMARILY KLWB/KBLF AND KBCB IN THE WEST AND KLYH IN THE EAST. MAY STILL SEE A BRIEF PERIOD OF MVFR IN FOG AT KDAN OTRW VFR AROUND KROA. SHOULD SEE MOST OF THE FOG/STRATUS ERODE BY 14Z...10AM WITH ONLY KLWB LIKELY HANGING ONTO POCKETS OF LOWER VSBYS A WHILE LONGER. ONCE THE FOG FADES AND THE MID DECK EXITS SHOULD SEE MAINLY VFR FOR MOST OF THE DAY WITH SCTD-BKN 4-6K FT CU FIELDS. ISOLATED CONVECTION AGAIN POSSIBLE ESPCLY IN SPOTS ALONG THE BLUE RIDGE AND OUT EAST SO INCLUDED A VCTS MENTION FROM KROA EAST BASED ON THE LATEST HRRR MODEL WHICH SHOWS A FEW CLUSTERS DEVELOPING FROM NW NC INTO THE VA PIEDMONT BY MID AFTERNOON. ELSW WILL LEAVE OUT FOR NOW GIVEN ISOLATED NATURE. AGAIN EXPECT ANY STORMS TO DIMINISH WITH LOSS OF HEATING FOLLOWED BY MAINLY CLEAR SKIES WITH ANOTHER ROUND OF MVFR/IFR FOG ESPCLY VALLEYS GIVEN LESS CLOUD COVER OVERNIGHT. PROXIMITY OF THE OLD FRONT AND TROPICAL AIRMASS JUST TO THE SOUTH... WHICH WILL BEGIN A NORTHWARD RETURN BY LATE WEEK...WILL MAINTAIN A DAILY THREAT FOR PATCHY FLIGHT RESTRICTIONS IN VICINITY OF MAINLY DIURNALLY DRIVEN SHOWERS/STORMS FOR MUCH OF THE REST OF THE WEEK...WITH A CONTINUED THREAT FOR RESTRICTIONS INTO THE OVERNIGHT PERIODS WHERE FOG DEVELOPS. MORE WIDESPREAD SHRA/TSRA LIKELY BY WEEKS END AHEAD OF A STRONGER COLD FRONT THAT LOOKS TO DIVE THRU THE REGION FRIDAY INTO FRIDAY NIGHT. IMPROVING CONDITIONS TO VFR LIKELY BEHIND THE FRONT ESPCLY ACROSS THE EAST FOR THE WEEKEND. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...JH NEAR TERM...DS/JH SHORT TERM...RAB LONG TERM...PH/RAB AVIATION...DS/JH/KM
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
731 AM EDT WED AUG 8 2012 .SYNOPSIS... A STATIONARY FRONT ACROSS THE MOUNTAINS WILL GRADUALLY DISSIPATE TODAY AS WEAK HIGH PRESSURE SLIDES EAST INTO THE REGION BY TONIGHT BEFORE WEAKENING ON THURSDAY. A STRONG COLD FRONT WILL SWEEP ACROSS THE REGION FRIDAY INTO FRIDAY EVENING...BRINGING ANOTHER ROUND OF SHOWERS AND STORMS...SOME POTENTIALLY STRONG. COOLER AND DRIER WEATHER IS EXPECTED BEHIND THE FRONT OVER THE WEEKEND INTO EARLY NEXT WEEK AS HIGH PRESSURE BUILDS INTO THE REGION. && .NEAR TERM /THROUGH TONIGHT/... AS OF 230 AM EDT WEDNESDAY... WEAK SURFACE BOUNDARY ACROSS THE MOUNTAINS WILL GRADUALLY FADE TODAY AS A MID LEVEL WAVE PASSES TO THE EAST BY AFTERNOON AND DRIER AIR ALOFT PER VAPOR LOOP ADVECTS IN FROM THE NW. HOWEVER THE LOW LEVELS WILL REMAIN RATHER MOIST AND GIVEN ANOTHER SUBTLE S/W PUSHING ACROSS THE WEST LATER ON CANT TOTALLY RULE OUT ADDED ISOLATED CONVECTION...ESPCLY BLUE RIDGE AND POINTS EAST...MAINLY SOUTH OF HIGHWAY 460 WHERE BOUNDARY LAYER MOISTURE/INSTABILITY WILL BE BETTER. LATEST LOCAL GUIDANCE AS WELL AS THE SPC WRF AND GFS HINT AT THIS WITH A FEW TSRA CLUSTERS DEVELOPING SW SECTIONS ALONG THE BLUE RIDGE PER DIFF HEATING UNDER WEAK THETA-E RIDGING...AND THEN OUT EAST JUST AHEAD OF WHAT WAS LEFT OF THE OLD FRONT. AGAIN GIVEN WEAK STEERING AND LOCAL CONVERGENCE/OUTFLOW COULD ALLOW FOR STORMS TO POP UP AND DUMP HEAVY RAINFALL BUT NOT THINKING MUCH MORE COVERAGE THAN CHANCE TO ISOLATED POPS TODAY. OTRW EXPECTING A GRADUAL RETURN TO MORE SUNSHINE AS THE HIGH/MID LEVEL CLOUD DECK ERODES AND SHIFTS NE WITH THE PASSAGE OF THE WAVE TO THE EAST THIS MORNING. THINK CLOUDS WILL LIMIT FOG FROM BECOMING TOO WIDESPREAD EXCEPT PERHAPS THE FAR WEST SO WILL KEEP MENTION PENDING RELEASE COVERAGE. WARM START AND SLIGHT 85H WARMING UNDER A WEAK WEST/NW TRAJECTORY ALOFT SHOULD PUSH TEMPS TO AROUND 90 EAST AND WELL INTO THE 80S WEST SO BUMPED UP CLOSER TO THE MAV VALUES TODAY. ANY CONVECTION SHOULD QUICKLY FADE WITH LOSS OF HEATING THIS EVENING GIVEN LACK OF SUPPORT...WITH MAINLY CLEAR SKIES AFTER MIDNIGHT AS WE SLIDE IN BETWEEN THE DEEP MOISTURE LOBE TO THE SE AND THE NEXT UPSTREAM 5H TROF. THUS WILL CARRY SOME ISOLATED EVENING POPS MAINLY SOUTH/EAST THEN GO DRY WITH PERHAPS SOME PATCHY FOG UNDER WEAK HIGH PRESSURE LATE. THIS SHOULD ALSO ALLOW LOW TEMPS TO DROP CLOSER TO THE COOLER MAV FOR THE MOST PART WITH RANGE FROM AROUND 60 VALLEYS TO UPPER 60S SE AND RIDGES. && .SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/... AS OF 430 AM EDT WEDNESDAY... ACTIVE WEATHER WILL BEGIN THE SHORT TERM PERIODS AS THE UPPER FLOW AMPLIFIES ACROSS THE U.S...FEATURING A DEEPENING NEGATIVELY TILTED UPPER TROUGH FROM THE GREAT LAKES TOWARD THE MID-ATLANTIC THU-FRI. THE POPS AND SEVERE THREAT FOR THU SOMEWHAT QUESTIONABLE...BUT A MORE DEFINITE POSSIBILITY FOR FRI AS THE ENTIRE SYSTEM SHIFTS ACROSS THE CWA. NORMALLY SUCH A PATTERN WOULD SUGGEST A HIGH THREAT OF SEVERE WX ACROSS THE REGION...ESPECIALLY FRI. HOWEVER...EXTENSIVE CLOUD COVER AND MORNING SHRA FRI WILL LIKELY LIMIT HEATING...WITH THE GREATER LIKELIHOOD FOR SEVERE PROBABLY FOCUSED ACROSS THE PIEDMONT AND TOWARD THE COASTAL PLAIN FRI AFTERNOON/EVENING. AT THIS POINT...HAVE ONLY MENTIONED GUSTY WINDS AND LOCALLY HEAVY RAIN. SPC HAS OUTLOOKED THE WESTERN SECTIONS ON DAY2 AND THE ENTIRE CWA ON DAY3...BUT AGAIN FEEL MAIN THREAT ON DAY3 SHOULD BE EAST OF THE BLUE RIDGE. MODEL AND HPC QPF NOT OVERLY IMPRESSIVE AND INDICATIVE OF A SKIP OVER EFFECT OF THE HEAVIEST PRECIPITATION AS AFOREMENTIONED TOWARD EASTERN VA/NC. NONETHELESS...WITH FAIRLY WIDESPREAD HEAVY RAIN ACROSS THE MOUNTAIN AREAS DURING THE PAST COUPLE OF WEEKS...LATER SHIFTS WILL NEED TO EVALUATE THE ISSUANCE OF AN FFA WEST OF THE BLUE RIDGE WHERE 1HR FFG VALUES GENERALLY LESS THAN 2 INCHES. WITH REFERENCE TO POP TIMING...ENOUGH FORCING APPEARS EVIDENT COMBINED WITH PRE-SYSTEM HEATING TO SUPPORT GOOD CHC POPS EAST TO LIKELY POPS WEST BY FRI EVENING. WILL HAVE LIKELY POPS TO ALL AREAS FRI...WHICH MAY WELL BECOME CATEGORICAL WITH LATER FORECASTS. 850MB TEMPS NEAR +20C ACROSS THE PIEDMONT REGION THU WILL STILL SUPPORT WELL ABOVE NORMAL TEMPS IN THE LOW TO MID 90S EAST OF THE BLUE RIDGE...WITH MOSTLY 80S TO THE WEST...EXCEPT 70S IN THE MOUNTAINS ABOVE 3000 FT. EXTENSIVE CLOUD COVER AND SHRA/TSRA FRI SHOULD HOLD TEMPS TO THE 70S IN THE MOUNTAINS TO 80S EAST OF THE BLUE RIDGE. LATEST MODELS HAVE COME INTO BETTER AGREEMENT IN PUSHING THE MAIN UPPER TROUGH EAST OF THE REGION BY EARLY SAT...WHICH SHOULD TAKE THE BULK OF THE PCPN WITH IT. HOWEVER...THE PARENT...RATHER DEEP UPPER LOW FOR MID-AUGUST...WILL SWEEP THROUGH CENTRAL PA SAT AND COULD PROMOTE ENOUGH LIFT IN UPSLOPE AREAS OF WV/N VA TO SUPPORT ISOLD -SHRA DURING DAYTIME HEATING...THUS HAVE INCLUDED SLIGHT CHC POPS ACCORDINGLY. 850MB TEMPS DROP TO THE LOWEST LEVELS SEEN IN OVER TWO MONTHS...WITH +10C ACROSS ALL EXCEPT THE PIEDMONT BY 12Z SAT. THIS SHOULD ALLOW FOR SOME RATHER REFRESHING HIGHS IN THE 70S WEST OF THE BLUE RIDGE AND 80S EAST...WITH DEWPOINTS DROPPING INTO THE 50S WEST OF THE BLUE RIDGE AND 60S ACROSS THE PIEDMONT. && .LONG TERM /SUNDAY THROUGH TUESDAY/... AS OF 430 AM EDT WEDNESDAY... HAVE NOT MADE ANY SIGNIFICANT CHANGES TO THE LONG TERM AT THIS TIME. IT APPEARS THAT A RATHER UNSETTLED WEATHER PATTERN WILL REMAIN IN PLACE THROUGHOUT THE EXTENDED AS A SERIES OF NW FLOW DISTURBANCES TRACK ACROSS THE REGION. THE ECMWF/GFS ARE AT ODDS WITH RESPECT TO THE AMPLIFICATION OF THE NEXT UPPER TROUGH TOWARD THE MIDDLE OF NEXT WEEK... WITH THE GFS FAVORING A FLATTER...MORE ZONAL FLOW. AT ANY RATE...IT APPEARS THAT AT LEAST CHC POPS FOR SHRA/TSRA WILL CONTINUE THROUGHOUT THE EXTENDED WITH TEMPS RETURNING BACK TO AOA NORMAL LEVELS. LOW-LEVEL MOISTURE WILL ALSO BE INCREASING...RESULTING IN INCREASINGLY MORE HUMID CONDITIONS AS WELL. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... AS OF 645 AM EDT WEDNESDAY... EXTENSIVE MID AND HIGH CLOUD CANOPY ASSOCIATED WITH WAVE/UPPER JET CONTINUES TO SLOWLY PUSH EAST AND SHOULD EXIT THE AREA BY MID MORNING IF NOT SOONER. MAY SEE A FEW ADDED SHRA DEVELOP OVER THE SW THIS MORNING BUT MOSTLY SOUTH OF THE TAF SITES. OTRW FOG THE MAIN CONCERN AGAIN EARLY THIS MORNING WITH AREAS OF IFR/LIFR IN THE VALLEYS/ALONG THE WESTERN RIDGES...PRIMARILY KLWB/KBLF AND KBCB IN THE WEST AND KLYH IN THE EAST. MAY STILL SEE A BRIEF PERIOD OF MVFR IN FOG AT KDAN OTRW VFR AROUND KROA. SHOULD SEE MOST OF THE FOG/STRATUS ERODE BY 14Z...10AM WITH ONLY KLWB LIKELY HANGING ONTO POCKETS OF LOWER VSBYS A WHILE LONGER. ONCE THE FOG FADES AND THE MID DECK EXITS SHOULD SEE MAINLY VFR FOR MOST OF THE DAY WITH SCTD-BKN 4-6K FT CU FIELDS. ISOLATED CONVECTION AGAIN POSSIBLE ESPCLY IN SPOTS ALONG THE BLUE RIDGE AND OUT EAST SO INCLUDED A VCTS MENTION FROM KROA EAST BASED ON THE LATEST HRRR MODEL WHICH SHOWS A FEW CLUSTERS DEVELOPING FROM NW NC INTO THE VA PIEDMONT BY MID AFTERNOON. ELSW WILL LEAVE OUT FOR NOW GIVEN ISOLATED NATURE. AGAIN EXPECT ANY STORMS TO DIMINISH WITH LOSS OF HEATING FOLLOWED BY MAINLY CLEAR SKIES WITH ANOTHER ROUND OF MVFR/IFR FOG ESPCLY VALLEYS GIVEN LESS CLOUD COVER OVERNIGHT. PROXIMITY OF THE OLD FRONT AND TROPICAL AIRMASS JUST TO THE SOUTH... WHICH WILL BEGIN A NORTHWARD RETURN BY LATE WEEK...WILL MAINTAIN A DAILY THREAT FOR PATCHY FLIGHT RESTRICTIONS IN VICINITY OF MAINLY DIURNALLY DRIVEN SHOWERS/STORMS FOR MUCH OF THE REST OF THE WEEK...WITH A CONTINUED THREAT FOR RESTRICTIONS INTO THE OVERNIGHT PERIODS WHERE FOG DEVELOPS. MORE WIDESPREAD SHRA/TSRA LIKELY BY WEEKS END AHEAD OF A STRONGER COLD FRONT THAT LOOKS TO DIVE THRU THE REGION FRIDAY INTO FRIDAY NIGHT. IMPROVING CONDITIONS TO VFR LIKELY BEHIND THE FRONT ESPCLY ACROSS THE EAST FOR THE WEEKEND. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...JH NEAR TERM...JH SHORT TERM...RAB LONG TERM...PH/RAB AVIATION...DS/JH/KM
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
126 AM EDT WED AUG 8 2012 .SYNOPSIS... A PERIOD OF UNSETTLED WEATHER WILL CONTINUE THIS WEEK AS A FRONTAL BOUNDARY OSCILLATES ACROSS THE MID ATLANTIC REGION. A STRONG COLD FRONT WILL SWEEP ACROSS THE REGION ON FRIDAY...BRINGING A GENEROUS COVERAGE OF SHOWERS AND STORMS...SOME POTENTIALLY STRONG. COOLER AND DRIER WEATHER IS EXPECTED BY THE START OF THE NEXT WEEK AS HIGH PRESSURE BUILDS INTO THE REGION. && .NEAR TERM /THROUGH TODAY/... AS OF 1000 PM EDT TUESDAY... THE FRONTAL BOUNDARY PER LATEST MSAS THETA-E/LI GRADIENT LIES FROM ERN KY ENE INTO CENTRAL VA. SHOWERS AND STORMS REMAIN ISOLATED AT BEST WITH BEST CONCENTRATION ACROSS THE NC FOOTHILLS. STORM MOVEMENT HAS BEEN ALL OVER THE PLACE WITH A WEAK FLOW. 00Z SOUNDINGS FROM RNK/GSO SHOW STORM MOTION OF 3 KNOTS OR LESS. LUCKILY HAVE NOT HAD STORMS LINGERING OVER ONE AREA TOO LONG AS THEY TEND TO FADE AFTER AN HOUR. WILL SEE A WEAKENING TREND TO THE ACTIVITY OVERNIGHT AND THINK A SLOW PUSH SOUTHEAST OF THE THETA-E RIDGE WILL KEEP AT LEAST A LOW CHANCE/SLIGHT CHANCE POPS AROUND ALL NIGHT FROM SOUTHSIDE VA/NW NC PIEDMONT WEST TO THE GRAYSON HIGHLANDS/NC MTNS. THE OTHER ISSUE TONIGHT WILL BE FOG AND HOW DENSE WILL IT GET. THE DENSE CANOPY OF CIRROSTRATUS CONTINUES ACROSS THE ENTIRE FORECAST AREA. MODELS SHOW DRIER AIR SNEAKING INTO THE MTNS AFTER 09Z...SO WILL SEE SOME CLEARING. WILL HAVE TO WATCH SFC OBS AND SAT TRENDS FOR POTENTIAL DENSE FOG ADVISORY. SOME SCHOOLS IN NC ARE STARTING IN THE MORNING SO FOG WILL CAUSE A PROBLEM THERE POTENTIALLY. WILL KEEP THE MENTION IN HWO FOR NOW. RAISED TEMPS/DEWPOINTS UP A DEGREE OR TWO OVERNIGHT MAINLY EAST OF THE NEW RIVER VALLEY WHERE THINK MORE CLOUDS ARE GOING TO LINGER THROUGH WED MORNING. PREVIOUS VALID DISCUSSION... ON WEDNESDAY...WE EXPECT ANOTHER DAY COMPARABLE TO TODAY AS FAR AS PRECIPITATION COVERAGE THANKS TO THE FRONT JUST TO OUR SOUTH. HOWEVER...WITH HIGH PRESSURE NOSING SOUTH...CLOUD COVER SHOULD BE LESS...AND A SLIGHTLY STRONGER CAP SHOULD MEAN THE ISOLATED SHOWERS SHOULD BE EVEN MORE ISOLATED. DESPITE THE FRONT BEING FARTHER TO OUR SOUTH...MORE SUNSHINE SHOULD YIELD HIGH TEMPERATURES ON WEDNESDAY ABOUT THREE TO FIVE DEGREES WARMER THAN TODAY. && .SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/... AS OF 242 PM EDT TUESDAY... CHANCES FOR THUNDERSTORMS WILL INCREASE THROUGH THE SHORT TERM PERIOD AS AN UPPER LEVEL TROF AMPLIFIES OVER THE GREAT LAKES AND INTO THE OHIO VALLEY BY FRIDAY. IN ADVANCE OF THIS SYSTEM...TEMPERATURES SHOULD WARM TOWARD THE WARMER NAM MOS VALUES ON THURSDAY AS THE LOW LEVEL THERMAL RIDGE NOSES INTO OUR AREA. BEST CHANCES FOR THUNDERSTORMS ON THURSDAY WILL BE IN THE WEST AS A LEAD SHORT WAVE (OVERDONE BY THE GFS) APPROACHES OUR AREA AND INTERACTS WITH A MODERATELY UNSTABLE AIRMASS. KEPT POPS IN THE EASTERN PORTION OF THE FORECAST AREA ON THURSDAY AS WEAK LOW LEVEL CONVERGENCE ALONG A LEE-SIDE TROF SHOULD GENERATE SCATTERED CONVECTION. THIS CONVECTION MAY LINGER A FEW HOURS BEYOND SUNDOWN THURSDAY NIGHT WITH SUPPORT FROM THE WEAK UPPER LEVEL WAVE MOVING THROUGH. THE TREND OF THE MODELS FOR FRIDAY`S SYSTEM HAS BEEN TO SLOW ITS EASTWARD PROGRESS SLIGHTLY. BY 00Z (8 PM EDT) SATURDAY...MOST MODELS SHOW THE COLD FRONT STILL WEST OF OUR FORECAST AREA. THE POTENTIAL EXISTS FOR STRONG TO SEVERE STORMS TO ERUPT IN ADVANCE OF THIS SYSTEM AS THE AREA COMES UNDER THE INFLUENCE OF THE RR QUAD OF AN UPPER LEVEL JET ROTATING AROUND THE EASTERN SIDE OF THE APPROACHING SHORT WAVE TROF. THE BIGGEST QUESTION CONCERNING THE POTENTIAL FOR SEVERE WEATHER WILL BE THE INSTABILITY. CLOUDS ON FRIDAY SHOULD KEEP HIGH TEMPS BELOW THURSDAY`S EXPECTED HIGHS AND MAY KEEP INSTABILITY DOWN. THE GFS CRAVEN SIG SVR PARAMETER FORECAST KEEPS THE HIGHEST POTENTIAL FOR SEVERE WEATHER TO OUR SOUTHEAST...WHERE INSTABILITY IS FORECAST TO BE HIGHER. CONSIDERING THE STRENGTH OF THIS UPPER LEVEL SYSTEM...WILL KEEP MENTION OF SVR WX IN THE HWO...ALONG WITH THE THREAT FOR HEAVY RAIN WITH PWATS EXPECTED TO EXCEED 2 INCHES IN THE EAST. && .LONG TERM /SATURDAY THROUGH TUESDAY/... AS OF 242 PM EDT TUESDAY... THE LONG RANGE MODELS ARE IN GOOD AGREEMENT THAT THE EASTERN U.S. REMAINS UNDER THE INFLUENCE OF AN UPPER TROF THAT DE-AMPLIFIES WITH TIME. AHEAD OF THE UPPER TROF...A STRONG COLD FRONT WILL SWEEP THROUGH FRIDAY NIGHT. THE 00Z ECMWF HOLDS MORE UPPER LEVEL ENERGY ON THE WEST SIDE OF THE UPPER TROF AND KEEPS PRECIP LINGERING IN THE FAR EASTERN PORTION OF OUR FORECAST AREA ON SATURDAY. SO WE HAVE DELAYED THE ENDING TIME OF THE PRECIP UNTIL MIDDAY SATURDAY. OTHERWISE...UPSLOPE RAIN SHOWERS CAN BE EXPECTED UNDER THE TROF AXIS AND LOW LEVEL NORTHWEST WINDS. DRIER...COOLER AND LESS HUMID AIR WILL INVADE THE REGION LATE SATURDAY INTO SUNDAY. THE GEFS SHOWS 850MB TEMPS BY 18Z SATURDAY WILL BE 1-2 STANDARD DEVIATIONS BELOW NORMAL. SO...LEANED TOWARD THE COOLER ECMWF VALUES FOR TEMPS SATURDAY NIGHT THROUGH SUNDAY NIGHT. TEMPERATURES WILL GRADUALLY WARM MONDAY AND TUESDAY AS THE UPPER LEVEL TROF RELAXES...BUT INDIVIDUAL SHORT WAVES MOVING THROUGH AN UPPER LEVEL NORTHWEST FLOW COMBINED WITH A WEAK SOUTHEAST FLOW WILL GENERATE AFTERNOON SHOWERS AND STORMS. && .AVIATION /05Z WEDNESDAY THROUGH SUNDAY/... AS OF 100 AM EDT WEDNESDAY... EXTENSIVE MID AND HIGH CLOUD CANOPY ASSOCIATED WITH WAVE/UPPER JET PERSISTS ACROSS THE REGION TONIGHT WITH SOME LOWER STRATO-CU CIGS ALONG THE WESTERN SLOPES ON THE EDGE OF THE CLOUD SHIELD. MAY SEE A FEW ADDED SHRA DEVELOP OVER THE WEST THRU DAWN OTRW THE MAIN CONCERN WITH FOG COVERAGE GIVEN LIMITED COOLING DUE TO CLOUD COVER. THINK ONCE THIS BACKEDGE CLEARS SE WVA WILL SEE KBLF/KLWB DROP TO MVFR/IFR...WITH LIFR AT KLWB IN THE NEXT FEW HOURS. THUS DELAYED ONSET OF LOWER VSBYS BY A COUPLE OF HOURS IN THE WEST INCLUDING KBCB WHICH MAY NOT DROP TO MVFR UNTIL JUST BEFORE DAWN. APPEARS THE CLOUD SHIELD MAY HOLD FOR MUCH OF THE OVERNIGHT FROM KROA EASTWARD WHICH WOULD CURTAIL MUCH FOG TO MAINLY SPOTTY COVERAGE IN THE LOWER SPOTS BY MORNING. THEREFORE ALSO CUT BACK ON FOG AT BOTH KDAN/KLYH UNTIL VERY LATE AND ONLY WENT WITH A BRIEF PERIOD OF MVFR FOR NOW. EXPECT ANY FOG OR LOW CIGS TO ERODE BY MID MORNING EXCEPT MAY HANG IN A BIT LONGER IN THE VALLEY AROUND KLWB. ELSW SHOULD SEE MAINLY VFR FOR MOST OF THE DAY WITH SCTD-BKN 4-6K FT CU FIELDS. ISOLATED CONVECTION AGAIN POSSIBLE ESPCLY IN SPOTS ALONG THE BLUE RIDGE AND OUT EAST BUT JUST TOO IFFY TO INCLUDE MENTION IN ANY TAF LOCATION AT THIS POINT. PROXIMITY OF OLD FRONT AND TROPICAL AIRMASS JUST TO THE SOUTH... WHICH WILL BEGIN A NORTHWARD RETURN BY LATE WEEK...WILL MAINTAIN A DAILY THREAT FOR PATCHY FLIGHT RESTRICTIONS IN VICINITY OF MAINLY DIURNALLY DRIVEN SHOWERS/STORMS FOR MUCH OF THE REST OF THE WEEK...WITH A CONTINUED THREAT FOR RESTRICTIONS INTO THE OVERNIGHT PERIODS WHERE FOG DEVELOPS. MORE WIDESPREAD SHRA/TSRA LIKELY BY WEEKS END AHEAD OF A STRONGER COLD FRONT THAT LOOKS TO DIVE THRU THE REGION FRIDAY INTO FRIDAY NIGHT. IMPROVING CONDITIONS TO VFR LIKELY BEHIND THE FRONT ESPCLY ACROSS THE EAST FOR THE WEEKEND. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...DS NEAR TERM...DS/WP SHORT TERM...PH LONG TERM...PH AVIATION...DS/JH/KM
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
931 PM CDT THU AUG 9 2012 .UPDATE...SHOWERS AND THUNDERSTORMS WILL CONTINUE TO DIMINISH OVER WESTERN CWA THROUGH THE LATE EVENING AS VIGOROUS MID-LEVEL WAVE SLIDES SOUTH OF THE REGION. FOCUS WILL THEN BE IN THE EAST WHERE INCREASING LOW LEVEL CONVERGENCE AROUND DEEPENING LOW PRESSURE OVER THE NORTHERN OHIO VALLEY AND LAKE ENHANCEMENT WILL RESULT IN SCATTERED TO NUMEROUS SHOWERS AND ISOLATED THUNDERSTORMS IN THE EAST THROUGH THE LATE NIGHT. WITH INCREASING LOW LEVEL MIXING AND EXPECTED SCT-BKN MID LEVEL CLOUDS...EXPECT ANY SIGNIFICANT FOG TO REMAIN CONFINED TO WI RIVER VALLEY OF FAR WESTERN CWA LATE TONIGHT. THERMAL TROUGH SETS UP OVER SOUTHERN WISCONSIN OVERNIGHT AND SEEING SOME SOUTHWEST MOVEMENT OF MID-CLOUDS OVER NRN WI FROM LATEST IR IMAGES. && .AVIATION/06Z TAFS/...SCATTERED TO NUMEROUS SHOWERS AND ISOLATED THUNDERSTORMS WILL CONTINUE TO CAUSE CIGS TO FLIRT WITH MVFR AT TIMES OVER EASTERN TAF SITES TONIGHT. CLOUDS AND LOW LEVEL MIXING ARE EXPECTED TO PREVENT SIGNIFICANT FOG SO WL HOLD OUT OF TAFS FOR NOW. CLEARING SKIES EXPECTED ON FRI. && .MARINE...TIGHTENING PRESSURE GRADIENT ASSOCIATED WITH DEEPENING LOW PRESSURE OVER THE CENTRAL GREAT LAKES OVERNIGHT ALONG WITH VERY STEEP LOW LEVEL LAPSE RATES WILL ALLOW WIND GUSTS TO 35 KNOTS TO REACH THE LAKE SURFACE LATE TONIGHT THROUGH FRIDAY. BESIDES LATEST NAM SHOWING POTENTIAL FOR GALES ALONG WITH LATEST RAP AND ARW MESOSCALE MODELS. THREAT FOR WATERSPOUTS WILL CONTINUE UNTIL LATE TONIGHT. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...SMALL CRAFT ADVISORY UNTIL 4 AM CDT FRIDAY FOR LMZ643>646. GALE WARNING FROM 4 AM TO 6 PM CDT FRIDAY FOR LMZ643>646. && $$ MBK
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
301 AM MDT FRI AUG 10 2012 .SHORT TERM...(TODAY THROUGH SATURDAY) ISSUED AT 300 AM MDT FRI AUG 10 2012 MODELS CONTINUE TO SHOW EMBEDDED WAVES IN THE MOIST FLOW WHICH COMBINING WITH AFTERNOON HEATING WILL BE THE FORCING MECHANISMS FOR CONVECTION TODAY. RUC13 SHOWS THE BEST DYNAMICS MOVING ACROSS THE EASTERN UTAH THIS MORNING INTO WEST-CENTRAL COLORADO BY THIS AFTERNOON. EXPECT ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS TO DEVELOP ACROSS THE ENTIRE FORECAST AREA...WITH THE BEST CHANCE OF LOCALLY HEAVY RAIN ACROSS SOUTHERN AND EXTENDING NORTH ACROSS CENTRAL SECTIONS TODAY. GUSTY OUTFLOW WINDS TO 50 MPH ARE ALSO POSSIBLE NEAR STORMS ESPECIALLY ACROSS CENTRAL AND NORTHERN SECTIONS. MORE ENERGETIC TROF MOVING INTO THE PACIFIC NORTHWEST LATE THIS EVENING WILL BE PUSHING ACROSS THE NORTHERN ROCKIES BY THIS TIME TOMORROW NIGHT. AS IT DOES SO THE UPPER HIGH WILL BE SUPPRESSED SOUTH OF THE 4 CORNERS REGION AND BRINGING IN SOME STRONGER WESTERLY FLOW AS THE GRADIENT TIGHTENS. THE GOES DERIVED SATELLITE IMAGERY THIS MORNING IS SHOWING GOOD MOISTURE OVER SOUTHERN CALIFORNIA/SOUTHERN NEVADA AND THE 320K MOISTURE TRANSPORT VECTS SHOW THIS MOISTURE BEING PULLED INTO OUR CWA AS IT GETS CAUGHT UP IN THE FASTER WESTERLIES. THERE IS NO DISTINCT OR STRONG FORCING FOR ASCENT EVIDENT IN THE SHORT TERM MODELS OVERNIGHT. HOWEVER BOTH GFS/NAM SHOW PWATS SURGING THROUGH THE EARLY MORNING HOURS AND POT VORT MOVING ALONG THE NORTHERN BORDER AS UPPER JET MAX APPROACHES SO THINK THERE WILL BE SOME LINGERING CONVECTION TO DEAL WITH AND BOOSTED POPS SLIGHTLY AND FAVORED ACROSS THE NORTHERN 1/3 OF THE CWA. WITH MOISTURE IN PLACE SATURDAY ADDED DYNAMICS FROM AN UPPER LEVEL SPEED MAX MOVING OVER NORTHERN COLORADO SHOULD LEAD TO ANOTHER ACTIVE DAY...THOUGH MODELS ARE A LITTLE DIFFERENT ON TIMING AND COVERAGE. NAM SOLN PVU FIELDS SHOW THE SHORT WAVE ENERGY DIPPING INTO NORTHERN COLORADO EARLY IN THE DAY AS IT HAS A STRONGER SYSTEM OVER THE NORTHERN ROCKIES...GFS NOT DEEPENING THE SYSTEM QUITE AS MUCH AND KEEPS ANY SHORT WAVE FORCING JUST NORTH OF OUR BORDER. BY AFTERNOON HOWEVER BOTH MODELS HAVE UPPER LEVEL DIVERGENCE OVER OUR CENTRAL CWA AND WEAK SUBSIDENCE FILTERING INTO THE NORTH. THE INHERITED POPS FOR SATURDAY COVERED THIS WELL AND MADE JUST A FEW TWEAKS UPWARD WITH SLIGHT HIGHER CONFIDENCE. STILL CHANCE OF HEAVY RAINFALL BUT STORM MOTIONS WILL BE ON THE INCREASE WHICH MAY ENHANCE THE OUTFLOW WIND THREAT. TEMPERATURES SHOWING DIVERGING TREND IN GUIDANCE WITH NAM LOWERING DUE TO BEING MORE ACTIVE. USED A BLEND BUT GAVE MORE WEIGHT TO THE WARMER GUIDANCE ATTM. .LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY) ISSUED AT 300 AM MDT FRI AUG 10 2012 AS THE FLOW BECOME MORE NORTHWESTERLY IN THE WAKE OF THE NORTHERN SYSTEM DRIER AIR LOOKS TO FILTER INTO THE CWA SATURDAY NIGHT WITH PWATS KNOCKING BACK TO UNDER .75 OVER ALL BUT THE FAR SOUTHWESTERN PORTION OF THE CWA. THIS SHOULD ALLOW CONVECTION TO TAPER OFF OVERNIGHT AND LEAD TO COOLER LOW TEMPERATURES. THIS DRY AIR WILL BE IN PLACE FOR ONLY A SHORT TIME AS PWATS LOOK TO REBOUND BY LATE SUNDAY AS THE UPPER HIGH CENTERS OVER THE SOUTHERN HIGH PLAINS. WITH A LATE MOISTURE PUSH SOME STORMS MAY MAKE IT INTO THE VALLEYS BUT FOR THE MOST PART THINK MOST STORM WILL BE MORE ROOTED TO THE TERRAIN. NOT MUCH CHANGE IN THE WEATHER PATTERN INTO THE EXTENDED PERIOD...WITH SOUTHERLY MOIST FLOW CONTINUING INTO THE EARLY WORK WEEK WITH A CHANCE OF AFTERNOON AND EVENING THUNDERSTORMS EXPECTED EACH DAY THROUGH WEDNESDAY. MODELS ARE HINTING AT THE RIDGE BUILDING TO OUR WEST BY THURSDAY WHICH WOULD GENERATE SLIGHTLY DRIER CONDITIONS BY LATE IN THE WEEK WITH A DECREASING THREAT OF SHOWERS AND THUNDERSTORMS. EXPECT SEASONABLY WARM TEMPERATURES THROUGH THE EXTENDED PERIOD. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY NIGHT) ISSUED AT 300 AM MDT FRI AUG 10 2012 INCREASED MOISTURE COMBINED WITH A WEAK DISTURBANCE MOVING OVER THE NORTHERN HALF OF THE FORECAST AREA WILL CONTINUE TO BRING ISOLATED SHOWERS AND A STRAY THUNDERSTORM DURING THE REMAINDER OF THE NIGHT. HOWEVER...EXPECT MVFR CONDITIONS THROUGH THIS MORNING. DIURNAL HEATING COMBINED WITH INCREASING MOISTURE WILL BRING ANOTHER ROUND OF SCATTERED SHOWERS AND THUNDERSTORMS THIS AFTERNOON WHICH WILL CONTINUE INTO THE EVENING HOURS. STORMS WILL INITIALLY FORM OVER THE HIGHER TERRAIN RESULTING IN AREAS OF MOUNTAIN OBSCURATION AND WIND GUSTS TO 45 MPH. STORMS WILL IMPACT LOWER ELEVATIONS AFTER 20Z BRINGING ISOLATED MVFR CIGS AND VSBY TO AIRPORTS ACROSS THE AREA...ESPECIALLY THOSE IN CLOSE PROXIMITY TO MOUNTAINOUS TERRAIN. GUSTY OUTFLOW WINDS TO 50 MPH WILL ALSO BE A MAIN CONCERN. SHOWERS AND EMBEDDED THUNDERSTORMS WILL DECREASE IN AREAL COVERAGE AND INTENSITY AFTER SUNSET. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...NONE. UT...NONE. && $$ SHORT TERM...15/MPM LONG TERM...MPM AVIATION...MPM
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
559 AM EDT FRI AUG 10 2012 .SYNOPSIS... A SLOW MOVING COLD FRONT WILL APPROACH THE FORECAST AREA FROM THE NORTHWEST THROUGH TONIGHT. THE FRONT WILL BECOME DIFFUSE SATURDAY. && .NEAR TERM /THROUGH TODAY/... MOISTURE WILL BE HIGH AHEAD OF THE SLOW MOVING COLD FRONT TODAY. EXPECT NUMEROUS SHOWERS AND THUNDERSTORMS MAINLY ASSOCIATED WITH THE H85 JET. THE RAP AND NAM INDICATE THE JET WILL MAINLY AFFECT THE FORECAST AREA EARLY TODAY. HOWEVER...CONTINUED HIGH MOISTURE AHEAD OF THE FRONT AND DIURNAL HEATING SUPPORTS ADDITIONAL SHOWERS AND THUNDERSTORMS LATER TODAY. LEANED TOWARD THE HIGHER GUIDANCE POPS. CLOUDINESS SHOULD LIMIT INSTABILITY. THE NAM/S FORECAST OF WEAK INSTABILITY APPEARS REASONABLE. IF SIGNIFICANT BREAKS AND STRONG HEATING DOES OCCUR THEN THERE WILL BE ENOUGH SHEAR FOR A FEW SEVERE THUNDERSTORMS. THE NAM SHOWS H85 WINDS NEAR 30 KNOTS MAINLY EARLY TODAY. BOTH THE NAM AND GFS SHOW RAINFALL AMOUNTS LESS THAN ONE-QUARTER OF AN INCH AND THESE GENERAL VALUES MAY BE CORRECT SINCE THE H85 JET MAXIMUM SHOULD BE NORTHEAST OF THE FORECAST AREA WHICH SHOULD LIMIT CONVERGENCE. HOWEVER...THERE WILL BE A THREAT OF VERY HEAVY RAIN BECAUSE OF PRECIPITABLE WATER VALUES AROUND 2 INCHES. ALSO...EXPECT 1000-500 MB THICKNESSES NEAR 574 WHICH IS THE PREFERRED VALUE FOR HEAVY RAIN IN AUGUST. USED THE GUIDANCE CONSENSUS FOR THE TEMPERATURE FORECAST. && .SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/... MOISTURE AND CONVERGENCE ASSOCIATED WITH THE SLOW MOVING FRONT SUPPORTS SHOWERS AND THUNDERSTORMS TONIGHT. HOWEVER...INSTABILITY SHOULD BE LIMITED BY PREVIOUS CONVECTION AND DIURNAL COOLING. FORECASTED POPS OF LIKELY EARLY AND CHANCE LATE. THE NAM AND GFS SHOW THE FRONT LINGERING NEAR THE FORECAST AREA SATURDAY AND SATURDAY NIGHT BUT DEEPER MOISTURE APPEARS TO SHIFT A LITTLE EAST OF THE FORECAST AREA SATURDAY. THE NAM AND GFS MOS SUPPORT CHANCE POPS. USED THE GUIDANCE CONSENSUS FOR THE TEMPERATURE FORECAST THROUGH THE PERIOD. && .LONG TERM /SUNDAY THROUGH THURSDAY/... THE GFS SHOWS RIDGING TO THE SOUTH WITH LEE-SIDE TROUGHING IN THE FORECAST AREA DURING MUCH OF THE EXTENDED PERIOD. THE PATTERN SUPPORTS MAINLY DIURNAL SCATTERED THUNDERSTORMS. THE GFS ENSEMBLE MEANS SUPPORT SLIGHT CHANCE OF CHANCE POPS. EXPECT TEMPERATURES NEAR CLIMATOLOGY WITH LOWS IN THE LOWER 70S AND HIGHS IN THE LOWERS 90S. && .AVIATION /09Z FRIDAY THROUGH TUESDAY/... LOW LEVEL JET AFFECTING THE AREA TODAY. SOUTH WIND 5-10 KT THIS MORNING WILL FAVOR STRATUS CLOUDS RATHER THAN DENSE FOG. GUIDANCE HAVE COME INTO AGREEMENT WITH LIFR/IFR CIGS ACROSS THE TAF SITES THROUGH 14-15Z. SO CONFIDENCE IS HIGH. COULD EVEN SEE A FEW SHOWERS EARLY THIS MORNING. EXPECT IMPROVING CONDITIONS BY 15Z-16Z. SOUTHWEST WINDS INCREASING TO 10-15KT BY MIDDAY WITH GUSTS NEAR 20 KNOTS. WIDESPREAD SHOWERS AND THUNDERSTORMS EXPECTED AGAIN THIS AFTERNOON INTO TONIGHT. EXTENDED AVIATION OUTLOOK...A COLD FRONT WILL MOVE THROUGH THE REGION SATURDAY THROUGH SUNDAY. AN UNSETTLED WEATHER WILL PERSIST THROUGH EARLY SUNDAY...WITH PERIODS OF SHOWERS AND THUNDERSTORMS. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
253 AM EDT FRI AUG 10 2012 .SYNOPSIS... A SLOW MOVING COLD FRONT WILL APPROACH THE FORECAST AREA FROM THE NORTHWEST THROUGH TONIGHT. THE FRONT WILL BECOME DIFFUSE SATURDAY. && .NEAR TERM /THROUGH TODAY/... MOISTURE WILL BE HIGH AHEAD OF THE SLOW MOVING COLD FRONT TODAY. EXPECT NUMEROUS SHOWERS AND THUNDERSTORMS MAINLY ASSOCIATED WITH THE H85 JET. THE RAP AND NAM INDICATE THE JET WILL MAINLY AFFECT THE FORECAST AREA EARLY TODAY. HOWEVER...CONTINUED HIGH MOISTURE AHEAD OF THE FRONT AND DIURNAL HEATING SUPPORTS ADDITIONAL SHOWERS AND THUNDERSTORMS LATER TODAY. LEANED TOWARD THE HIGHER GUIDANCE POPS. CLOUDINESS SHOULD LIMIT INSTABILITY. THE NAM/S FORECAST OF WEAK INSTABILITY APPEARS REASONABLE. IF SIGNIFICANT BREAKS AND STRONG HEATING DOES OCCUR THEN THERE WILL BE ENOUGH SHEAR FOR A FEW SEVERE THUNDERSTORMS. THE NAM SHOWS H85 WINDS NEAR 30 KNOTS MAINLY EARLY TODAY. BOTH THE NAM AND GFS SHOW RAINFALL AMOUNTS LESS THAN ONE-QUARTER OF AN INCH AND THESE GENERAL VALUES MAY BE CORRECT SINCE THE H85 JET MAXIMUM SHOULD BE NORTHEAST OF THE FORECAST AREA WHICH SHOULD LIMIT CONVERGENCE. HOWEVER...THERE WILL BE A THREAT OF VERY HEAVY RAIN BECAUSE OF PRECIPITABLE WATER VALUES AROUND 2 INCHES. ALSO...EXPECT 1000-500 MB THICKNESSES NEAR 574 WHICH IS THE PREFERRED VALUE FOR HEAVY RAIN IN AUGUST. USED THE GUIDANCE CONSENSUS FOR THE TEMPERATURE FORECAST. && .SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/... MOISTURE AND CONVERGENCE ASSOCIATED WITH THE SLOW MOVING FRONT SUPPORTS SHOWERS AND THUNDERSTORMS TONIGHT. HOWEVER...INSTABILITY SHOULD BE LIMITED BY PREVIOUS CONVECTION AND DIURNAL COOLING. FORECASTED POPS OF LIKELY EARLY AND CHANCE LATE. THE NAM AND GFS SHOW THE FRONT LINGERING NEAR THE FORECAST AREA SATURDAY AND SATURDAY NIGHT BUT DEEPER MOISTURE APPEARS TO SHIFT A LITTLE EAST OF THE FORECAST AREA SATURDAY. THE NAM AND GFS MOS SUPPORT CHANCE POPS. USED THE GUIDANCE CONSENSUS FOR THE TEMPERATURE FORECAST THROUGH THE PERIOD. && .LONG TERM /SUNDAY THROUGH THURSDAY/... THE GFS SHOWS RIDGING TO THE SOUTH WITH LEE-SIDE TROUGHING IN THE FORECAST AREA DURING MUCH OF THE EXTENDED PERIOD. THE PATTERN SUPPORTS MAINLY DIURNAL SCATTERED THUNDERSTORMS. THE GFS ENSEMBLE MEANS SUPPORT SLIGHT CHANCE OF CHANCE POPS. EXPECT TEMPERATURES NEAR CLIMATOLOGY WITH LOWS IN THE LOWER 70S AND HIGHS IN THE LOWERS 90S. && .AVIATION /07Z FRIDAY THROUGH TUESDAY/... LOW LEVEL JET AFFECTING THE AREA TODAY. SOUTH WIND 5-10 KT THIS MORNING WILL FAVOR STRATUS CLOUDS RATHER THAN FOG. GUIDANCE HAVE COME INTO AGREEMENT WITH LIFR/IFR CIGS ACROSS THE TAF SITES THROUGH 14-15Z. SO CONFIDENCE IS HIGH. COULD EVEN SEE A FEW SHOWERS EARLY THIS MORNING. EXPECT IMPROVING CONDITIONS BY 15Z-16Z. SOUTHWEST WINDS INCREASING TO 10-15KT BY MIDDAY WITH GUSTS NEAR 20 KNOTS. WIDESPREAD SHOWERS AND THUNDERSTORMS EXPECTED AGAIN THIS AFTERNOON INTO TONIGHT. EXTENDED AVIATION OUTLOOK...AN UNSETTLED WEATHER WILL PERSIST THROUGH SUNDAY. A COLD FRONT WILL MOVE SLOWLY THROUGH THE REGION FRIDAY THROUGH SUNDAY...THEREBY HOLDING A GOOD CHANCE FOR CONVECTION. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
305 AM CDT FRI AUG 10 2012 .DISCUSSION... ISSUED 305 AM CDT FRI AUG 10 2012 SHORT TERM...TODAY THROUGH SUNDAY UNSEASONABLY DEEP UPPER-LEVEL LOW WILL CONTINUE TO SPIN OVER THE GREAT LAKES TODAY. POCKET OF VERY COLD AIR ALOFT CHARACTERIZED BY 500MB TEMPS OF -14 TO -16C WILL PRODUCE ENOUGH DAYTIME INSTABILITY TO TRIGGER PLENTY OF DIURNAL CLOUDINESS AND EVEN A FEW ISOLATED SHOWERS ALONG THE ILLINOIS/INDIANA BORDER. TIGHTENING PRESSURE GRADIENT BETWEEN DEVELOPING SURFACE LOW OVER THE OHIO RIVER VALLEY AND APPROACHING HIGH ACROSS THE PLAINS WILL CREATE GUSTY NORTHERLY WINDS...WITH FORECAST SOUNDINGS SUGGESTING GUSTS TO AROUND 25 MPH. THANKS TO THE BRISK NORTHERLY FLOW AND PARTIAL CLOUD COVER...HIGH TEMPS WILL REMAIN BELOW NORMAL FOR THIS TIME OF YEAR IN THE MIDDLE TO UPPER 70S. SKIES WILL CLEAR AND WINDS WILL DIMINISH TONIGHT...ALLOWING EXCELLENT RADIATIONAL COOLING CONDITIONS TO DEVELOP. OVERNIGHT LOW TEMPERATURES WILL GENERALLY DROP INTO THE MIDDLE TO UPPER 50S...WITH A FEW FAVORED LOCATIONS DIPPING INTO THE LOWER 50S. PLENTY OF SUNSHINE AND CONTINUED COOL WEATHER WILL CONTINUE INTO SATURDAY...WITH AIRMASS MODIFICATION PRODUCING HIGHS AROUND 80 DEGREES. MODELS CONTINUE TO ADVERTISE NEXT SHORT-WAVE APPROACHING FROM THE NORTHWEST BY LATE SUNDAY. GIVEN DRY AIRMASS AND SLIGHTLY SLOWER ARRIVAL OF WAVE...WILL KEEP PRECIP CHANCES OUT OF THE FORECAST THROUGH THE DAY SUNDAY. STRONGER SYNOPTIC LIFT WILL ARRIVE WITH THE WAVE BY SUNDAY NIGHT...SO WILL INTRODUCE A CHANCE FOR SHOWERS/STORMS AT THAT TIME. LONG TERM...MONDAY THROUGH THURSDAY SCATTERED SHOWERS/STORMS WILL LINGER INTO MONDAY...BEFORE WAVE PUSHES EAST OF THE REGION AND DRY WEATHER RETURNS MONDAY NIGHT AND TUESDAY. UPPER HEIGHTS WILL BEGIN TO RISE IN THE WAKE OF THE SYSTEM...ALTHOUGH LATEST MODEL RUNS DO NOT BUILD RIDGING INTO THE MIDWEST QUITE AS AGGRESSIVELY AS PREVIOUS RUNS. WILL SEE A DEFINITE WARMING TREND NEXT WEEK...HOWEVER HAVE TEMPERED THE READINGS A BIT...WITH HIGHS ONLY BACK INTO THE UPPER 80S BY WEDNESDAY. MODELS STILL SHOWING SOME TIMING DISCREPANCIES WITH NEXT APPROACHING WAVE...BUT CONSENSUS BRINGS IT INTO THE AREA WEDNESDAY NIGHT/THURSDAY. GIVEN PROJECTED STRENGTH OF FEATURE AND EXPECTED SUPPLY OF AVAILABLE MOISTURE...THINK CHANCE POPS FOR SHOWERS/STORMS ARE WARRANTED AT THAT TIME. BARNES && .AVIATION... ISSUED 1145 PM CDT THU AUG 9 2012 MAIN CONCERN IS WITH TIMING FOR POTENTIAL MVFR/IFR CEILINGS. LARGE UPPER LOW CURRENTLY CENTERED JUST NORTH OF KORD AND WILL MOVE INTO NORTHERN INDIANA BEFORE SUNRISE. SATELLITE AND SURFACE OBS SHOWING AN INCREASE IN MVFR CONDITIONS NEAR/NORTH OF THIS LOW...AND THIS WILL BE SWINGING SOUTHWARD ACROSS ILLINOIS OVER THE NEXT FEW HOURS. LATEST GUIDANCE FROM THE RAP MODEL SUGGESTING THESE LOWER CEILINGS WILL PUSH INTO CENTRAL ILLINOIS FROM THE NORTHEAST... SO WILL BEGIN WITH THE LOWER CEILINGS NEAR KBMI/KCMI AT THE START OF THE TAF PERIOD WITH SOME TEMPO VFR CONDITIONS THROUGH ABOUT 08Z. THE REMAINDER OF THE TAFS SHOULD SEE CLOUDS LOWERING TO 1000-2000 FEET BEGINNING AROUND 08Z...ALTHOUGH SOME BREAKS IN THE CLOUDS WILL STILL BE POSSIBLE. A STEADIER BREAK-UP OF THE CLOUDS IS EXPECTED TO DEVELOP SHORTLY AFTER SUNRISE...AS THE LOW PULLS EAST OF THE REGION. VFR CONDITIONS SHOULD PREVAIL BY LATE MORNING. NORTH WINDS SHOULD PICK UP SOME ON FRIDAY...AS CLOUDS DECREASE AND ALLOW FOR SOME MIXING TO TAKE PLACE FROM AROUND 5000 FEET. MAY SEE SOME GUSTS OF 15-20 KNOTS IN A FEW AREAS DURING THE MIDDAY AND AFTERNOON HOURS. WINDS WILL DIMINISH TOWARD SUNSET. GEELHART && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1146 PM CDT THU AUG 9 2012 .DISCUSSION... ISSUED 833 PM CDT THU AUG 9 2012 STRONGEST CONVECTION WHICH PRODUCED SEVERE WEATHER REPORTS FROM BLOOMINGTON TO PARIS EASTWARD HAS PUSHED INTO INDIANA...BUT SOME SHOWERS AND THUNDERSTORMS LINGER OVER CENTRAL AND SOUTHEAST ILLINOIS. MANY OF THESE WERE ALONG AN OUTFLOW BOUNDARY...WHICH WAS IN AN ARCH FROM FULTON COUNTY TO EFFINGHAM...THEN NORTHEAST TO NEAR DANVILLE. MESOANALYSIS SHOWING SOME AREAS OF CAPES ABOVE 1000 J/KG LINGERING OVER CENTRAL AND SOUTHEAST ILLINOIS. HOWEVER... THE WINDOW OF OPPORTUNITY FOR ADDITIONAL SEVERE WEATHER IS NARROWING...AS ANOTHER BOUNDARY DROPS SOUTH FROM NORTHERN ILLINOIS AND LOWERS TEMPERATURES INTO THE 60S. THE CLEARING THAT HAS BEEN OCCURRING OVER THE CWA WILL FILL BACK IN AGAIN...AS A LARGE UPPER LOW DROPS SOUTH OUT OF WISCONSIN. HAVE SENT SOME ZONE/GRID UPDATES FOR THE LATEST CONVECTIVE TRENDS...AND SOME MINOR ADJUSTMENTS TO THE HOURLY TEMPERATURES. OVERALL LOWS FOR TONIGHT STILL LOOK GOOD. GEELHART && .AVIATION... ISSUED 1145 PM CDT THU AUG 9 2012 MAIN CONCERN IS WITH TIMING FOR POTENTIAL MVFR/IFR CEILINGS. LARGE UPPER LOW CURRENTLY CENTERED JUST NORTH OF KORD AND WILL MOVE INTO NORTHERN INDIANA BEFORE SUNRISE. SATELLITE AND SURFACE OBS SHOWING AN INCREASE IN MVFR CONDITIONS NEAR/NORTH OF THIS LOW...AND THIS WILL BE SWINGING SOUTHWARD ACROSS ILLINOIS OVER THE NEXT FEW HOURS. LATEST GUIDANCE FROM THE RAP MODEL SUGGESTING THESE LOWER CEILINGS WILL PUSH INTO CENTRAL ILLINOIS FROM THE NORTHEAST... SO WILL BEGIN WITH THE LOWER CEILINGS NEAR KBMI/KCMI AT THE START OF THE TAF PERIOD WITH SOME TEMPO VFR CONDITIONS THROUGH ABOUT 08Z. THE REMAINDER OF THE TAFS SHOULD SEE CLOUDS LOWERING TO 1000-2000 FEET BEGINNING AROUND 08Z...ALTHOUGH SOME BREAKS IN THE CLOUDS WILL STILL BE POSSIBLE. A STEADIER BREAK-UP OF THE CLOUDS IS EXPECTED TO DEVELOP SHORTLY AFTER SUNRISE...AS THE LOW PULLS EAST OF THE REGION. VFR CONDITIONS SHOULD PREVAIL BY LATE MORNING. NORTH WINDS SHOULD PICK UP SOME ON FRIDAY...AS CLOUDS DECREASE AND ALLOW FOR SOME MIXING TO TAKE PLACE FROM AROUND 5000 FEET. MAY SEE SOME GUSTS OF 15-20 KNOTS IN A FEW AREAS DURING THE MIDDAY AND AFTERNOON HOURS. WINDS WILL DIMINISH TOWARD SUNSET. GEELHART && .PREV DISCUSSION... ISSUED 300 PM CDT THU AUG 9 2012 INITIAL CONCERN IS WITH CHANCES FOR SEVERE STORMS LATE THIS AFTERNOON AND THIS EVENING. NEXT HIGHLIGHTS WILL BE THE COOLER AIRMASS FOR THE WEEKEND FOLLOWED BY A COUPLE OF CHANCES FOR RAIN SUNDAY NIGHT INTO MONDAY AND WEDNESDAY NIGHT INTO THURSDAY. OUR CURRENT WEATHER IS BEING DRIVEN BY WEAK CYCLOGENESIS THAT APPEARS TO BE CENTERED JUST NORTH OF PEORIA...ALONG A SURFACE TROUGH EXTENDING NORTH FROM LOW PRESSURE IN SOUTHERN IL. THAT LOW WAS LOCATED ALONG A STATIONARY FRONT THAT EXTENDED ROUGHLY ALONG THE OHIO RIVER VALLEY AND SOUTHWEST INTO OKLAHOMA. ALOFT...A WELL DEVELOPED TROUGH ACROSS THE GREAT LAKES WAS BEING REINFORCED BY A CLOSED LOW AT 500MB DROPPING SOUTH FROM NW WISCONSIN TOWARD NORTHERN IL. A NORTH-SOUTH ORIENTED 115 KT 300MB JET MAX WAS POSITIONED JUST WEST OF THE 500MB LOW...AND ROTATING SOUTH AND EAST AROUND THE UPPER TROUGH. MODELS ARE HAVING A DIFFICULT TIME CATCHING UP WITH THE WEAK SURFACE PRESSURE PATTERN THAT IS BEGIN EASILY ALTERED BY STORM OUTFLOWS/GUST FRONTS/COLD POOLS. IN GENERAL...WE DECIDED TO LEAN MORE CLOSELY WITH THE 00Z ECMWF. SHORT TERM...TONIGHT THROUGH SUNDAY. SOME FILTERED SUNSHINE HAS HELPED THE AIRMASS DESTABILIZE EARLY THIS AFTERNOON. SFC BASED CAPES HAVE CLIMBED TO AROUND 1500 J/KG WITH MU CAPES OF 2000 J/KG JUST EAST OF THE SFC CYCLOGENESIS NEAR PEORIA. EFFECTIVE SHEAR HAS INCREASED TO AROUND 25 TO 30KT. THAT HAS HELPED A FEW STORMS DEVELOP UNDER THE LOW NW OF PEORIA. VERTICAL DEVELOPMENT OF THOSE STORMS HAVE REMAINED IN CHECK SO FAR...WITH STORM TOPS AROUND 30K FT. ENOUGH OF A DRY LAYER BELOW 700MB WILL ALLOW FOR SOME ENHANCED DOWNBURST POTENTIAL WITH ANY STRONGER STORMS...AND THE FREEZING LEVEL DOWN AROUND 12K FT WILL BE MORE FAVORABLE FOR HAIL PRODUCTION. WE WILL MONITOR STORM PROGRESS AND DEVELOPMENT CLOSELY FOR AN INTENSIFICATION...BUT THE BETTER CHANCES FOR SEVERE STORMS APPEARS TO BE IN OUR EAST AND SOUTHEAST COUNTIES CLOSER TO THE STATIONARY FRONT AND SURFACE LOW IN SOUTHERN ILLINOIS. THE DY1 SLIGHT RISK WAS EXPANDED WESTWARD AT 17Z TO INCLUDE ALL BUT OUR FAR W-NW COUNTIES...SO WILL NOT RULE OUT SEVERE CHANCES AS FAR WEST AS THE ILLINOIS RIVER. WE WILL KEEP HIGH CHANCE POPS FOR EVERYWHERE THE REST OF THE AFTERNOON AND ACROSS THE EASTERN HALF THIS EVENING...AS THE WEAK SURFACE LOW NEAR PEORIA SLIDES EAST-SOUTHEAST TOWARD INDIANA. AFTER MIDNIGHT...ANY LINGERING SHOWERS/STORMS SHOULD BE CONFINED TO OUR COUNTIES EAST OF I-57. THE COLD POOL ALOFT WILL BE REINFORCED BY THE PASSAGE OF THE CLOSED LOW ACROSS NE ILLINOIS LATER TONIGHT AND FRIDAY. THE UPPER LOW IS THEN EXPECTED TO ROTATE BACK NORTHEAST INTO THE CENTRAL GREAT LAKES AND LINGER THERE SATURDAY BEFORE LIFTING NORTHEAST INTO ONTARIO SAT NIGHT. THAT SCENARIO WILL PUT CENTRAL ILLINOIS IN A COOL NORTHWEST FLOW ALOFT...WITH WEAK SURFACE HIGH PRESSURE HELPING TO PROVIDE DRY CONDITIONS FRIDAY INTO SUNDAY. BELOW NORMAL HIGHS ARE EXPECTED FRIDAY THROUGH SUNDAY. FRIDAY WILL BE THE COLDEST DAY WITH HIGHS ONLY IN THE UPPER 70S...THEN HIGHS WILL CLIMB INTO THE LOWER 80S FOR SAT AND SUN. THE ECMWF AND GFS BOTH SHOW A WEAK SFC LOW EJECTING FROM THE PLAINS ACROSS MISSOURI ON SUNDAY...POSSIBLY BRINGING A CHANCE OF RAIN WEST OF I-55 SUNDAY AFTERNOON. WE DECIDED TO INTRODUCE SLIGHT CHANCE POPS SUNDAY...THEN INCREASE TO CHANCE POPS SUNDAY NIGHT AS THE LOW REACHES WESTERN IL AND THE 500MB TROUGH DROPS SOUTHEAST INTO NORTHERN IL. A FEW STORMS MAY DEVELOP SUNDAY NIGHT DUE TO THE STEEP LAPSE RATES IN THE COLD POOL ALOFT. LONG TERM...MONDAY THROUGH THURSDAY WE HELD ONTO SLIGHT CHANCE POPS ON MONDAY BEFORE THE SURFACE TROUGH DISSIPATES AND THE UPPER TROUGH SLIDES EAST OF IL. A REINFORCING PUSH OF COLDER AIR ALOFT WILL HELP TO KEEP LOWS SLIGHTLY BELOW NORMAL AGAIN ON MONDAY...IN THE LOW TO MID 80S. WEAK SURFACE RIDGING SHOULD GIVE US BETTER CHANCES OF REMAINING DRY AGAIN MONDAY NIGHT THROUGH WEDNESDAY. HOWEVER...THE NORTHWEST FLOW ALOFT ALWAYS LEAVES THE DOOR OPEN FOR AN UNRESOLVED SHORTWAVE TO SLIP INTO THE AREA AND KICK OFF A FEW SHOWERS/STORMS. FOR NOW...WE KEPT THE FORECAST DRY UNTIL A MORE PROMINENT WEATHER DISTURBANCE IS FORECAST TO ARRIVE WED NIGHT AND THURSDAY. SOME WEAK SOUTHERLY FLOW DEVELOPING ON WED SHOULD HELP HIGH TEMPS RETURN TO THE UPPER 80S BOTH WED AND THURS. SHIMON && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS DES MOINES IA
404 AM CDT FRI AUG 10 2012 .SHORT TERM /TONIGHT/... MAIN FOCUS TODAY WILL BE ON CLOUD COVER AND TEMPERATURES FOR THE NEAR TERM. CWA TO REMAIN BENEATH CYCLONIC FLOW ALOFT...WITH WEAK CAA EXPECTED THROUGHOUT THE DAY. SOME LOW LEVEL MOISTURE RESULTING IN AN AREA OF LOW STRATUS CONTINUES TO DEVELOP OFF TO THE NORTHEAST OF THE CWA...WITH MODEL PROGGING THIS AREA OF STRATUS TO CONTINUE TO SPREAD/ADVECT INTO THE NORTHERN/EASTERN HALF OF THE CWA THROUGH SUNRISE. HRRR MODEL AND GOES-R WRF FORECAST BOTH HANDLING THE DEVELOPMENT OF THIS STRATUS WELL AND HAVE TAILORED SKY GRIDS TOWARD THE MODEL/SATELLITE PRODUCT TRENDS. EXPECT STRATUS TO LIFT/BREAK UP TOWARD MID/LATE MORNING ACROSS THE AREA...WITH RESULTANT MID LEVEL CU FIELD POSSIBLE. OTHERWISE MUCH DRIER TO MOVE INTO THE CWA WITH DEWPOINTS EXPECTED TO CONTINUE TO DROP TO AROUND 50 POSSIBLY EVEN INTO THE 40S WITH DRIER AIR MIXING DOWN AND ADVECTING INTO THE CWA IN NORTHERLY FLOW. WITH THE CAA...EXPECT TEMPS TO BE A FEW DEGREES COOLER THAN YESTERDAY WITH HIGHS MAINLY IN THE UPPER 70S TO AROUND 80. .LONG TERM /TONIGHT THROUGH THURSDAY/... CANADIAN HIGH PRESSURE MOVING INTO THE NORTHERN PLAINS EARLY THIS MORNING WITH TEMPERATURES DIPPING INTO THE LOW TO MID 40S OVER THE SOUTHEAST QUADRANT. THIS SYSTEM WILL SETTLE SOUTH TODAY AND BE STRETCHED OVER MUCH OF THE CENTRAL AND NORTHERN PLAINS TONIGHT. WHILE SOME MODIFICATION OF TEMPERATURES IS EXPECTED...SHOULD HAVE OVERNIGHT LOWS TONIGHT TOUCHING THE MID 40S AT A FEW LOCATIONS ACROSS THE NORTH AND INTO THE LOW TO MID 50S ELSEWHERE. THE CLOSED UPPER LOW THAT AFFECTED THE AREA ON THURSDAY WILL BE SHIFTING SLOWLY NORTHEAST ACROSS THE CENTRAL GREAT LAKES THROUGH MID DAY SATURDAY BEFORE GAINING STEAM SATURDAY NIGHT AS ANOTHER CLOSED UPPER LOW MOVES INTO CENTRAL CANADA. THIS WILL ALLOW A TRANSITION TO A MORE PROGRESSIVE NORTHWEST FLOW THAT WILL PERSIST THROUGH MUCH OF THE EXTENDED. A FAIRLY SIGNIFICANT SYSTEM WILL ARRIVE OVER THE PACIFIC NW LATE TODAY THEN MOVE ACROSS THE ROCKIES AND PRODUCE LEE SIDE CYCLOGENESIS INTO SATURDAY. SATURDAY WILL BE ANOTHER PLEASANT DAY AND EXPECT TEMPERATURES TO BE NEAR THE HIGH END OF GUIDANCE WITH DRY SFC AIR HEATING UP EFFICIENTLY. MID LEVEL THETA-E ADVECTION WILL COMMENCE SATURDAY NIGHT WITH THE INITIAL WAVE BEING SPENT ON MID LEVEL SATURATION. GULF MOISTURE WILL BREAK FREE AND BEGIN TO STREAM NORTHWARD SATURDAY NIGHT AS WELL WITH THE MOISTURE ADVECTION ARRIVING LATE AIDED BY AN INCREASING LOW LEVEL JET APPROACHING 40 KTS. THE COMBINATION OF THE MULTI LEVEL KINEMATICS AND THERMODYNAMICS WILL RESULT IN A DEEPLY FORCED SYSTEM WITH SHOWERS AND THUNDERSTORMS ARRIVING OVER THE WEST AFTER MIDNIGHT. ADDITIONAL CHANCES WILL CONTINUE SUNDAY AND SUNDAY NIGHT WITH AS THE SECOND SEGMENT OF THE UPPER LEVEL SYSTEM ARRIVES ALONG WITH THE SFC LOW REFLECTION. GENERAL AGREEMENT DEVELOPING THAT THE SFC LOW WILL SHIFT EAST ACROSS SOUTHERN IA AND WOULD ALLOW A PORTION OF THE WARM SECTOR TO LIFT INTO THE STATE. HIGH VARIABILITY POSSIBLE WITH HIGH TEMPERATURES ON SUNDAY WHERE HIGHS COULD STRUGGLE IN THE 60S UNDER INCREASING CLOUDS AND MORE PROLONGED PRECIPITATION WHILE RISING WELL INTO THE 80S SOUTH WHERE SOME SUN COULD BE POSSIBLE. THIS COULD LEAD TO AN AREA OF SFC BASED THUNDERSTORMS AND AN AREA WITH SEVERE POTENTIAL. PRECIPITATION CHANCES CONTINUE OVER MAINLY THE EAST SUNDAY EVENING BEFORE ENDING. THE REMAINDER OF THE EXTENDED IS HIGHLIGHTED BY SEVERAL IMPULSES RIPPLING THROUGH THE NW FLOW WHILE A DEEP UPPER LEVEL LOW DROPS INTO ALBERTA AND MANITOBA BY MID WEEK. OVERALL TIMING BECOMES DIFFICULT UNDER THESE SITUATIONS BUT GENERAL CONSENSUS IS A WEAK WAVE ARRIVING TUE NIGHT INTO WED WITH A MORE SIGNIFICANT SYSTEM IMPACTING THE AREA TOWARD THE END OF THE PERIOD AS ENERGY ASSOCIATED THE SOUTHERN CANADA SYSTEM ARRIVES. && .AVIATION...10/06 HIGH PRESSURE FROM CENTRAL ONT INTO SWRN NEBRASKA WILL BUILD SOUTH INTO IOWA THROUGH THE PERIOD. VFR CONDITIONS ARE EXPECTED FOR THE MORT PART WITH A NE-NLY FLOW OVER THE SITES. SOME FOG IS POSSIBLE AROUND SUNRISE OVER THE NORTH WHERE WINDS WILL LIGHTEN UP AND IN THE EAST WHERE SHOWERS MOVED THROUGH IN THE EVENING. TIMEFRAME IS 10Z-14Z. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...BEERENDS LONG TERM...DONAVON AVIATION...MS AUG 12
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1256 AM EDT FRI AUG 10 2012 ...Updated Aviation Discussion... .Forecast Update... Issued at 1145 PM EDT Thu Aug 9 2012 Updated the forecast to adjust POPs a bit. The 0Z NAM seems to have the best handle on convection this evening. Convection over central IN right around the sfc low should continue to move east over the next 2-4 hrs and may develop a bit further south into our southern Indiana counties. However, these storms should struggle to reach severe levels given the lack of forcing further removed from the front and main upper level wave as well as lack of instability due to storms early this evening. The next area of focus looks to be southern IL as wind shear profiles increase with the upper shortwave dropping south through IL and into western KY through the early morning hours. SPC mesoanalysis indicates good moisture convergence along the sfc front over southern IL with some isld-sct cells noted over western IL to southeast MO. DCAPE values are at a relative max over southern IL and western KY. Would expect new convection to develop over southern IL over the next 2-4 hours, initially push SSE, and then pivot more easterly into our area during the pre-dawn hours and as the shortwave pivots aloft. This will probably be our best chance for strong to severe convection overnight. Forecast confidence in this occurring is low to medium given model inconsistencies and banking on convection developing over southern IL. && .Short Term (Tonight through Friday Night)... Issued at 331 PM EDT Thu Aug 9 2012 ...Active Period of Weather Expected This Afternoon and Tonight... Fairly active period of weather is shaping up for the Ohio Valley this afternoon and tonight. In the near term, mid-level shortwave combined with surface temperatures hitting convective temperatures has resulted in convection firing across the region. Several areas of convection are occurring across the area. The first is an organizing line near the I-75 corridor in our eastern sections. This is being forced by the aforementioned mid-level wave and by diurnal heating. This activity will continue to head east and into WFO JKL`s area over the next hour or so. Further west, a well defined residual outflow boundary was located along our border with WFO IND. This boundary extends from northern Dubois county NE to Jefferson County. Convection is firing along this boundary due to strong moisture convergence and diurnal heating. This activity should head east-southeast over the next few hours. Finally additional convection is firing also over west KY. Based on the latest runs of the LMK WRF and 4km HRRR runs, this activity should also head east-southeast and may impact our far southwestern counties later this afternoon. Based on RUC proximity soundings, this afternoon`s convective activity is likely to remain in the pulse variety with damaging winds, torrential rains and intense CG lightning being the main threats. Latest deterministic and ensemble model runs seem to be showing some forecast convergence with the forecast for later this evening and overnight. First mid-level trough will scoot east this evening while a secondary and more potent mid-level trough dropping down into the Ohio Valley late tonight. As this wave drops south, surface cyclone near KSTL will shift northeast while associated surface cold drags behind. Strong mid-level height falls will result in widespread synoptic scale lift across the region late tonight. This combined with forcing along the front should result in a secondary line of convection developing to our northwest and slide southeast overnight. Despite this line moving through during an instability minimum, the upper level dynamics appear to be strong enough to support convection despite the meager instability. Current thinking is that a convective line will generate along the I-70 corridor and then drop southeast overnight. The line will likely be strong to possibly severe especially to our northwest. However, as the line heads southeast, it is possible that line may weaken a bit as it slides through KY. Convection should be pushing through southern Indiana in the 04-06Z time frame and then through KY in the 06-11Z time frame. Have gone ahead and bumped up PoPs for the overnight period. Lows will remain mild with temperatures falling into the lower-mid 60s in the northwest and mid-upper 60s elsewhere. For Friday, the main forecast change here is that a lot more cloud cover will be likely during the morning hours. Latest model time-height model cross sections show plenty of low-level moisture lingering behind the frontal boundary as it pushes through. Thus, mostly cloudy skies seem very likely in the morning followed by progressive clearing during the afternoon and into the evening hours. Highs tomorrow will be quite cool compared to what we`ve seen over the last few months. We should see readings in the upper 70s in the east with upper 70s to lower 80s in the central and west. Lows Friday night will be quite comfortable with lows in the mid-upper 50s. .Long Term (Saturday through Thursday)... Issued at 315 PM EDT Thu Aug 9 2012 ...Mostly Sunny, Dry, and Cool Weekend Ahead... A vertically stacked unseasonably far south and strong closed low will begin to slowly fill over Lake Huron Saturday. This system will slowly weaken and slowly lift north towards St. James Bay by late Sunday. In its wake, it will leave residual troughing across the western Great Lakes and the upper Midwest. By early Saturday, the occluded front related to this upper low will already have moved well east of the Commonwealth. Much drier and cooler air originating in Canada, will have overspread the state by dawn Saturday. Expect mostly clear skies and relatively cool temperatures for the upcoming weekend. Dewpoints will likely fall into the lower 50s by Saturday afternoon. Highs will struggle to exceed 80 on Saturday with highs on Sunday warming just a few degrees into the lower 80s. Overnight lows early Sunday will quite likely reach into the upper 50s, with perhaps our urban areas remaining near 60. A broad longwave trough will remain centered roughly over the Great Lakes during the early portion of next week. This will ensure no repeat of the excessively hot temperatures of early August anytime soon. Both the latest GFS and the ECMWF show a disturbance sliding southeast towards the base of this longwave trough Monday and Tuesday. This system will approach the Commonwealth by late Monday. At the surface, this system will likely aid in the formation of a weak surface trough that may serve as a focus for convection beginning late Monday, possibly continuing through the bulk of Tuesday. Will introduce a chance of storms for the later half of Monday, extending through Tuesday. Temperatures will warm a bit within the Monday through Thursday time period. However, even by Wednesday through Friday, temperatures will not exceed our seasonal mid-August averages with highs remaining in the upper 80s to around 90 && .Aviation (06Z TAF issuance)... Issued at 1255 AM EDT Fri Aug 10 2012 Main focus overnight will be convective chances ahead of a cold frontal passage. Currently, frontal boundary appears to be oriented along, but just north of the Ohio River and will remain nearly stationary for a few more hours. Then, a potent upper level wave will swing through the area toward dawn, helping to usher the surface front through. Chances for showers and storms will continue until this passage occurs later this morning, with the best chance of a storm at SDF. Am not confident enough to go with a prevailing thunder group at this time so will leave VCTS/CB mention until 7 AM EDT. Frontal boundary looks to move through the TAF sites sometime between 6 AM and 11 AM with a brief potential for low MVFR or IFR ceilings. Surface winds will also veer to westerly and then northwesterly through the end of the forecast period with the passage. Speeds should generally be around 10 mph. Ceilings should improve through midday and the afternoon, however at least MVFR stratocu will again be possible overnight tonight. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...NONE. KY...NONE. $$ Update...........AMS Short Term.......MJ Long Term........JSD Aviation.........BJS
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1132 PM CDT THU AUG 9 2012 .AVIATION...06Z TAFS FOR KOMA...KLNK AND KOFK. LIGHT NORTHEAST WINDS WILL CONTINUE OVERNIGHT WITH CLEAR SKIES. COULD BE SOME MVFR FOG AT KOMA/KOFK FROM ABOUT 10-14Z. NORTHEAST WINDS AROUND 8KTS AFTER THAT THROUGH THE REMAINDER OF FRIDAY WITH CUMULUS CLOUDS DEVELOPING AGAIN AROUND 5000 FEET BY LATE MORNING THROUGH THE AFTERNOON. DEWALD && .PREV DISCUSSION... /ISSUED 305 PM CDT THU AUG 9 2012/ DISCUSSION... TEMPERATURES WILL PROVIDE THE PRIMARY FORECAST CHALLENGES THROUGH FRIDAY NIGHT...THEN ATTENTION SHIFTS MORE TOWARD PRECIPITATION CHANCES OVER THE WEEKEND. MAIN FEATURES FROM THE 12Z UPPER AIR CHARTS THIS MORNING SHOWED THE FOLLOWING. AT 300 MB...JETSTREAM CURVED NORTHEAST ACROSS THE PACIFIC NORTHWEST INTO THE NORTHERN PLAINS...THEN TURNED SOUTHEAST INTO THE OHIO VALLEY. A JET MAX OF AROUND 100 KNOTS WAS NOTED OVER MINNESOTA. AT 500 MB...A RATHER IMPRESSIVE CLOSED LOW WAS OVER NORTHEAST MINNESOTA WITH 12 HOUR HEIGHT FALLS OF 70 METERS NOTED AT KINL. THE CENTER OF A MID LEVEL RIDGE WAS OVER THE FOUR CORNERS REGION. COOLER AIR WAS PUSHING DOWN FROM MINNESOTA AND THE EASTERN DAKOTAS AT 700 MB AND 850 MB. SURFACE ANALYSIS EARLY THIS AFTERNOON INDICATED A RIDGE OF COOL HIGH PRESSURE EXTENDING FROM ONTARIO AND MANITOBA DOWN INTO THE NORTHERN AND WESTERN PLAINS. WINDS WERE MAINLY FROM THE NORTH OVER THE LOCAL AREA. THAT SURFACE RIDGE WILL BUILD EASTWARD ACROSS THE FORECAST AREA TONIGHT THROUGH FRIDAY NIGHT...WITH SEASONABLE TEMPERATURES AND DRY CONDITIONS. EXPECT SOME PATCHY FOG TONIGHT AS WINDS DECREASE... ESPECIALLY IN PARTS OF OUR CENTRAL AND EASTERN ZONES WHERE SPOTTY RAIN FELL YESTERDAY AND TUESDAY. EXPECT THAT TO BURN OFF QUICKLY FRIDAY...IF IT DEVELOPS...WITH SCATTERED CUMULUS MOST AREAS BY THE AFTERNOON. HIGHS FRIDAY WILL BE IN THE 80S...CLOSE TO NAM MOS. RETURN FLOW STRENGTHENS LATE FRIDAY NIGHT INTO SATURDAY AND MODELS ARE IN GENERAL AGREEMENT WITH LARGE SCALE PATTERN. THEY SHOW SOME 850-700 MB THETA E ADVECTION SPREADING FROM WEST TO EAST ON SATURDAY. LARGE SCALE FORCING SEEMS WEAK AT BEST...SO KEPT POPS ONLY AT 20 PERCENT AND TRIED TO CONFINE THOSE TO NORTHEAST NEBRASKA SATURDAY. A MODEST SHORTWAVE TROUGH DOES MOVE ACROSS THE PLAINS FOR SATURDAY NIGHT/EARLY SUNDAY...AND THIS IS PROBABLY OUR BEST CHANCE FOR THUNDERSTORMS. THE 12Z GFS SEEMED WAY TOO GENEROUS WITH QPF AND ITS OUTPUT WAS GENERALLY NOT USED. FAVORED A BLEND OF THE NAM AND ECMWF FOR NOW...BUT SHOULD BE ABLE TO ADJUST THINGS MORE AS WE GET CLOSER WITH 4 KM NAM AND HRRR MODELS. LINGERED SOME LOW POPS INTO SUNDAY BASED ON CURRENT MODEL TIMING OF FORCING. OTHERWISE...LOOK FOR DEAMPLIFICATION OF THE 500 MB PATTERN THROUGH THE WEEKEND AND INTO EARLY NEXT WEEK AS RIDGE SHIFTS FROM THE FOUR CORNERS REGION TO THE SOUTHERN PLAINS. AS HEIGHTS INCREASE BY MID WEEK...HIGHS IN THE 90S WILL BECOME COMMON AGAIN. MILLER && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
153 AM EDT FRI AUG 10 2012 .SYNOPSIS... A TROUGH OF LOW PRESSURE OVER THE PIEDMONT THIS AFTERNOON THROUGH FRIDAY WILL GIVE WAY TO A COLD FRONT ON SATURDAY. HIGH PRESSURE WILL BUILD INTO THE AREA EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1045 PM THURSDAY...CONTINUED MAIN DILEMMA FOR THE OVERNIGHT PERIOD WILL BE THE TIMING AND COVERAGE OF THE CONVECTIVE ACTIVITY APPROACHING FROM THE SOUTHWEST. VARIOUS MODEL BUFR SOUNDINGS INDICATE AN INCREASE IN MOISTURE THIS EVENING AND OVERNIGHT VIA PWS REBOUNDING BACK OVER 2+ INCHES. WEAK MID LEVEL SHEARED VORT AND AN UPPER LEVEL JET MAX TO TRACK NE ACROSS THE CAROLINAS TONIGHT...WITH THE RIGHT REAR QUADRANT OF THIS UPPER JET AND SOURCE OF UPPER LEVEL DIVERGENCE TO PUSH ACROSS OR AFFECT THE FA MAINLY AFTER MIDNIGHT TONIGHT. THE RR QUAD WILL BE A FAVORED AREA OF UVVS AND AS A RESULT WILL INCREASE POPS TO GOOD CHANCE OR POSSIBLY LIKELY LEADING TO BUT MAINLY OCCURRING AFTER MIDNIGHT TONIGHT. THE DAYS HEATING COMBINED WITH DYNAMICS ALOFT HAS HELPED CONVECTION REACH SVR CRITERIA WELL UPSTREAM FROM THE FA. THE DAYS INSOLATION WILL BE DONE-WITH BY THE TIME THE BULK OF THE PCPN PUSHES TO/ACROSS THE ILM CWA LATER TONIGHT...AND AS A RESULT DO NOT ANTICIPATE PULSING SVR ACTIVITY. HOWEVER...DO LIKE THE HEAVY RAIN/GUSTY WINDS TO SUFFIX AFTER THE MENTIONING OF THE CONVECTION OVERNIGHT. EXPECT 20-30 MPH STORM MOTIONS...WHICH SHOULD HELP LOWER THE FLOOD POTENTIAL. HOWEVER...IF ACTIVITY BEGINS TO TRAIN...THEN WILL HAVE TO REVISIT THE FLOOD ISSUE. AS FOR MIN TEMPS...WILL STAY ON THE HIGHER SIDE OF MOS GUIDANCE DUE TO SKIES HAVING CLOUDED UP ALONG WITH THE POTENTIAL MORNING OCCURRENCE OF PCPN. && .SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/... AS OF 2 PM THURSDAY...AN AMPLIFYING H5 TROUGH...APPROACHING COLD FRONT AND PRECIPITABLE WATER SURGING ABOVE 2 INCHES WILL RESULT IN AN UNSETTLED SHORT TERM PERIOD. THE FRONT IS EXPECTED TO STALL IN THE VICINITY AS IT BECOMES ORIENTED WITH THE FLOW ALOFT. THUS THE FORECAST INDICATES CHANCE TO LIKELY POPS THROUGH SATURDAY NIGHT. FAVORED THE COOLER MET NUMBERS EACH DAY GIVEN THE EXPECTED CLOUD COVER. THE CLOUD COVER COULD ALSO LIMIT DEEPER CONVECTION FROM DEVELOPING...HOWEVER HEATING WILL LIKELY LEAD TO AT LEAST MODERATE INSTABILITY. && .LONG TERM /SUNDAY THROUGH THURSDAY/... AS OF 2 PM THURSDAY...COLD FRONT WILL BE MOVING OFFSHORE WHILE DISSIPATING AT THE START OF THE PERIOD. THIS WILL BRING AN END TO PRECIP THROUGH SUNDAY AFTN AS DRIER AND COOLER AIR WORKS IN BEHIND THIS BOUNDARY. FORECAST SOUNDINGS SUGGEST CLEARING WILL OCCUR RAPIDLY DURING SUNDAY...BUT EVEN WITH AMPLE SUNSHINE...TEMPS WILL STRUGGLE TO CLIMO AS SOME COOL ADVECTION OCCURS THROUGH MAX HEATING. EXPECT TEMPS AT OR JUST BELOW 90 SUNDAY WITH MINS FALLING TO NEAR 70. UPPER TROUGH WEAKENS AND SPINS OFF TO THE NORTHEAST AS SUBTLE RIDGING DEVELOPS ACROSS THE SOUTHEAST. RISING 1000-500MB THICKNESSES AND WARMING MID-LEVEL TEMPS WILL COMBINE WITH DRY W/NW FLOW TO PREVENT WIDESPREAD CONVECTION MON EVEN WITH SLIGHTLY STEEPENED ML LAPSE RATES. MOISTURE RETURN IS SLOW TO DEVELOP TUESDAY...BUT SOME GUIDANCE INDICATING THAT A COASTAL TROUGH MAY HELP SPREAD SOME MOISTURE TOWARDS THE COAST AND WILL BUMP POP TO CHC TUESDAY...ACROSS THE EAST. TEMPS WILL REMAIN AROUND CLIMO...A FEW DEGREES EITHER SIDE OF 90 AND 70. FOR THE MID/LATE WEEK...BROAD TROUGHING REMAINS ACROSS THE EAST WHILE WEAK IMPULSES MAY SPAWN AFTERNOON STORMS EACH DAY. HOWEVER...WITH MID LEVEL DRY AIR PERSISTING...CONVECTION WILL BE CAPPED AT SCHC/SILENT THIS FAR OUT IN TIME. A REINFORCING SHOT OF COOL/DRY AIR MAY PUSH THROUGH THURSDAY AS UPPER VORT MOVES ACROSS NEW ENGLAND WHICH WILL HELP KEEP TEMPS RIGHT AROUND CLIMO THROUGH THE END OF THE PERIOD. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... AS OF 06Z...EXPECT VCTS AT ILM UNTIL AROUND 07Z. PRECIP ENDS BUT REDEVELOPS COAST TERMS AFT 08Z-09Z. AT FLO/LBT TEMPO MVFR CIGS/VSBYS IN BR 08-12Z. CONFIDENCE IN TIMING OF BR OR RW NOT REAL HIGH. TEMPO MVFR LIKELY WITH PRECIP...BUT WILL NOT INCLUDE IFR DUE TO SCT NATURE OF ACTIVITY ALTHOUGH SHORT TERM IFR PSBL IF CELL MOVES OVR A COAST TERM. AS A SHORT WAVE APPROACHES PRECIP RE-DEVLPS BTWN COAST TERMS AND INLAND TERMS BY 18Z...BUT CONFIDENCE LOW DUE TO SUBSIDENCE BEHIND THIS MORNINGS ACTIVITY. IF DEVELOPMENT OCCURS IFR/TS WILL OCCUR MAINLY COAST TERMS 18-00Z. LOW CONFIDENCE TS AT FLO/LBT 18-00Z. EXTENDED OUTLOOK...CHANCE OF MORNING MVFR VSBYS IN BR WITH A CHANCE OF SHOWERS AND THUNDERSTORMS THROUGH SUNDAY. VFR MONDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 1045 PM THURSDAY...PROGGED SFC PRESSURE PATTERN AND TIGHTENING GRADIENT...WILL YIELD WINDS FROM SSW-SW THIS EVENING AND OVERNIGHT...ALONG WITH SPEEDS INCREASING FROM AROUND 15 KT...EXCEPT 15-20 KT FOR THE ILM NC WATERS. SIGNIFICANT SEAS ...MAINLY FROM WIND DRIVEN 3-5 SECOND PERIOD WAVES...WILL BUILD TO 3 TO 5 FT NORTH OF LITTLE RIVER INLET...AND 2 TO 4 FT SOUTH OF THE INLET. SEAS ARE EXPECTED TO BUILD TO 4 TO 6 FT FOR THE ILM NC WATERS FRIDAY...WITH SW WINDS 15-20 KT. STILL NOT ALL THAT CONFIDENT AT THE MOMENT WITH REGARD TO RAISING A SCA/SCEC. IF DATA FROM TONIGHTS 00Z EARLY MODEL RUNS INDICATE THIS INCREASED SCA POTENTIAL...MAY GO AHEAD AND ISSUE A SCA OR SCEC AT THE LATE NIGHT UPDATE. SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 2 PM THURSDAY...SOUTH-SOUTHWEST FETCH WILL BE IN PLACE THROUGH THE BULK OF THE SHORT TERM PERIOD. IT APPEARS THE PRESSURE GRADIENT WILL BE AT ITS GREATEST LATE FRIDAY AFTERNOON INTO THE EVENING. THE FLOW WILL FINALLY BEGIN TO WEAKEN SATURDAY NIGHT WITH THE FRONT IN THE VICINITY. SEAS MAY REACH MARGINAL SMALL CRAFT THRESHOLDS BY FRIDAY EVENING...WITH EXERCISE CAUTION CONDITIONS EXPECTED DURING THE MAJORITY OF THE PERIOD. LONG TERM /SUNDAY THROUGH TUESDAY/... AS OF 2 PM THURSDAY...PREDOMINANT SW FLOW TO PERSIST THROUGH THE EXTENDED AS BERMUDA HIGH RIDGES IN FROM THE EAST. A FAIRLY WEAK PRESSURE GRADIENT WILL EXIST HOWEVER...SO WINDS WILL BE AROUND 10 KTS OR LESS THROUGH MUCH OF THE PERIOD. THE LIGHT WINDS WILL PRODUCE A 2-3FT/5SEC SW WIND CHOP WHICH WILL COMBINE WITH A 2FT/9SEC SE SWELL TO PRODUCE OVERALL WAVE HEIGHTS OF 2-3 FT. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY FROM 6 AM THIS MORNING TO 9 AM EDT SATURDAY FOR AMZ250-252. && $$ AVIATION...MRR
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
601 AM EDT FRI AUG 10 2012 .SYNOPSIS... A SLOW MOVING COLD FRONT WILL APPROACH THE FORECAST AREA FROM THE NORTHWEST THROUGH TONIGHT. THE FRONT WILL BECOME DIFFUSE SATURDAY. && .NEAR TERM /THROUGH TODAY/... MOISTURE WILL BE HIGH AHEAD OF THE SLOW MOVING COLD FRONT TODAY. EXPECT NUMEROUS SHOWERS AND THUNDERSTORMS MAINLY ASSOCIATED WITH THE H85 JET. THE RAP AND NAM INDICATE THE JET WILL MAINLY AFFECT THE FORECAST AREA EARLY TODAY. HOWEVER...CONTINUED HIGH MOISTURE AHEAD OF THE FRONT AND DIURNAL HEATING SUPPORTS ADDITIONAL SHOWERS AND THUNDERSTORMS LATER TODAY. LEANED TOWARD THE HIGHER GUIDANCE POPS. CLOUDINESS SHOULD LIMIT INSTABILITY. THE NAM/S FORECAST OF WEAK INSTABILITY APPEARS REASONABLE. IF SIGNIFICANT BREAKS AND STRONG HEATING DOES OCCUR THEN THERE WILL BE ENOUGH SHEAR FOR A FEW SEVERE THUNDERSTORMS. THE NAM SHOWS H85 WINDS NEAR 30 KNOTS MAINLY EARLY TODAY. BOTH THE NAM AND GFS SHOW RAINFALL AMOUNTS LESS THAN ONE- QUARTER OF AN INCH AND THESE GENERAL VALUES MAY BE CORRECT SINCE THE H85 JET MAXIMUM SHOULD BE NORTHEAST OF THE FORECAST AREA WHICH SHOULD LIMIT CONVERGENCE. HOWEVER...THERE WILL BE A THREAT OF VERY HEAVY RAIN BECAUSE OF PRECIPITABLE WATER VALUES AROUND 2 INCHES. ALSO...EXPECT 1000-500 MB THICKNESSES NEAR 574 WHICH IS THE PREFERRED VALUE FOR HEAVY RAIN IN AUGUST. USED THE GUIDANCE CONSENSUS FOR THE TEMPERATURE FORECAST. && .SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/... MOISTURE AND CONVERGENCE ASSOCIATED WITH THE SLOW MOVING FRONT SUPPORTS SHOWERS AND THUNDERSTORMS TONIGHT. HOWEVER...INSTABILITY SHOULD BE LIMITED BY PREVIOUS CONVECTION AND DIURNAL COOLING. FORECASTED POPS OF LIKELY EARLY AND CHANCE LATE. THE NAM AND GFS SHOW THE FRONT LINGERING NEAR THE FORECAST AREA SATURDAY AND SATURDAY NIGHT BUT DEEPER MOISTURE APPEARS TO SHIFT A LITTLE EAST OF THE FORECAST AREA SATURDAY. THE NAM AND GFS MOS SUPPORT CHANCE POPS. USED THE GUIDANCE CONSENSUS FOR THE TEMPERATURE FORECAST THROUGH THE PERIOD. && .LONG TERM /SUNDAY THROUGH THURSDAY/... THE GFS SHOWS RIDGING TO THE SOUTH WITH LEE-SIDE TROUGHING IN THE FORECAST AREA DURING MUCH OF THE EXTENDED PERIOD. THE PATTERN SUPPORTS MAINLY DIURNAL SCATTERED THUNDERSTORMS. THE GFS ENSEMBLE MEANS SUPPORT SLIGHT CHANCE OF CHANCE POPS. EXPECT TEMPERATURES NEAR CLIMATOLOGY WITH LOWS IN THE LOWER 70S AND HIGHS IN THE LOWERS 90S. && .AVIATION /10Z FRIDAY THROUGH TUESDAY/... LOW LEVEL JET AFFECTING THE AREA TODAY. SOUTH WIND 5-10 KT THIS MORNING WILL FAVOR STRATUS CLOUDS RATHER THAN FOG. GUIDANCE HAVE COME INTO AGREEMENT WITH LIFR/IFR CIGS ACROSS THE TAF SITES THROUGH 14-15Z. SO CONFIDENCE IS HIGH. COULD EVEN SEE A FEW SHOWERS EARLY THIS MORNING. EXPECT IMPROVING CONDITIONS BY 15Z-16Z. SOUTHWEST WINDS INCREASING TO 10-15KT BY MIDDAY WITH GUSTS NEAR 20 KNOTS. WIDESPREAD SHOWERS AND THUNDERSTORMS EXPECTED AGAIN THIS AFTERNOON INTO TONIGHT. EXTENDED AVIATION OUTLOOK...AN UNSETTLED WEATHER WILL PERSIST THROUGH SUNDAY. A COLD FRONT WILL MOVE SLOWLY THROUGH THE REGION FRIDAY THROUGH SUNDAY...THEREBY HOLDING A GOOD CHANCE FOR CONVECTION. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$
AREA FORECAST DISCUSSION...UPDATED
NWS NASHVILLE TN
1158 PM CDT THU AUG 9 2012 .UPDATE...FOR 06Z AVIATION DISCUSSION. && .AVIATION...06Z AVIATION DISCUSSION. UNCERTAINTIES...SFC FRONTAL MOVEMENT IMPACTS. AS SFC FRONT MOVES CLOSER/EVENTUALLY THRU CKV/BNA...EXPECT SOME MOISTURE POOLING IN ITS VICINITY...MENTIONED MVFR FOG/CEILINGS...TEMPO IFR CSV...BUT EVEN WITH POSSIBLE SHORT WAVE PASSAGE IN UPPER LEVEL FLOW AIDING... WILL JUST MENTION VCSH AT CKV/BNA. FRONT SHOULD BE W OF CSV THRU AROUND 10/18Z...AND BELIEVE WITH DIURNAL INFLUENCES KICKING IN... THAT CB/VCTS TSTM CSV APPROPRIATE. A DRYING AIRMASS SHOULD ESTABLISH ITSELF ACROSS THE MID STATE BY 11/00Z TO SUPPORT SKC CONDITIONS. && .PREV DISCUSSION.../ISSUED 1011 PM CDT THU AUG 9 2012/ UPDATE... OTHER THAN THE ISOL CONVECTION OVER WESTERN MIDDLE TN...NOT MUCH GOING ON. BOUNDARY STILL LOCATED A GOOD DISTANCE TO OUR NW. NUMERICAL POPS ARE QUITE LOW THROUGH 12Z. HRRR NOW SHOWING SOME REDEVELOPMENT WITH THE FRONTAL BOUNDARY AFT 08Z OR SO. PRESSURE RISES ARE FAIRLY STRONG NORTH OF THE FRONTAL BOUNDARY. THUS...BOUNDARY SHOULD STILL BE ON THE APPROACH THROUGH 12Z. WILL GO AHEAD AND LOWER POPS TO THE 30-40 PERCENT RANGE FOR THE DURATION. HRRR DOES MAKE A COMEBACK WITH THE CONVECTION BUT PRIMARILY IS SERVING AS THE LONE MODEL...AND EVEN IF THE HRRR PANS OUT...THE ACTIVITY DOES NOT LOOK ALL THAT ORGANIZED. FOR THE UPDATE WILL LOWER POPS. UPDATE OUT SHORTLY. PREV DISCUSSION.../ISSUED 703 PM CDT THU AUG 9 2012/ UPDATE...FOR 00Z AVIATION DISCUSSION. AVIATION...00Z AVIATION DISCUSSION. UNCERTAINTIES...SFC FRONTAL MOVEMENT IMPACTS. CONVECTION TO OUR NW AHEAD OF FRONT MAINLY DISSIPATED...AND WITH AN OVERALL DRIER AIRMASS IN PLACE ACROSS THE MID STATE PER MORNING`S CONVECTION...PCPN CHANCES SLIGHT AT BEST THRU 10/10Z AND WILL NOT MENTION. AS SFC FRONT MOVES CLOSER/EVENTUALLY THRU CKV/BNA...EXPECT SOME MOISTURE POOLING IN ITS VICINITY...MENTIONED MVFR FOG/CEILINGS...TEMPO IFR CSV...BUT EVEN WITH POSSIBLE SHORT WAVE PASSAGE IN UPPER LEVEL FLOW AIDING...JUST DOUBT WITH ANY DIURNAL INFLUENCES NOT YET ESTABLISHED...PCPN WILL OCCUR. FRONT SHOULD BE W OF CSV THRU AROUND 10/18Z...AND BELIEVE WITH DIURNAL INFLUENCES KICKING IN...THAT CB/VCTS TSTM CSV APPROPRIATE. PREV DISCUSSION.../ISSUED 602 PM CDT THU AUG 9 2012/ UPDATE... NOT IMPRESSED WITH THE CHANCES FOR CONVECTION OVERNIGHT. ONLY BULLISH TRENDS I SEE ARE WITH THE WRF AND THE FROPA WHICH IS EXPECTED AT 12Z. OTW...UPPER DYNAMICS LOOKING WEAK WITH AN OVERALL DECREASE IN MOISTURE DEPTH FROM 00Z TO 06Z. HRRR SHOWS ZILCH THROUGH 6Z AND UPPER DIVERGENCE QUITE WEAK THROUGH 12Z ON THE GFS AND NAM. I WILL GO AHEAD AND UPDATE GRIDS AD KNOCK POPS DOWN PRIOR TO 06Z. AFT 06Z...WILL KEEP THE LIKELY POPS GOING ACROSS THE NORTH BUT THIS MAY NEED A DOWNWARD YANK AS WELL LATER IN THIS SHIFT. REMAINDER OF FCST LOOKS TO BE IN GOOD SHAPE. NO MENTION OF FOG CURRENTLY AND I SEE NO REASON TO ADD ANY AS TOVERS REMAIN NEAR TO ABOVE 0. MIN TEMP FCST LOOKS TO BE IN GOOD SHAPE. UPDATE OUT SHORTLY. PREV DISCUSSION.../ISSUED 340 PM CDT THU AUG 9 2012/ SHORT TERM...SHOWERS AND CLOUDS THAT STILL LINGERED ALONG THE CUMBERLAND PLATEAU AT MID-AFTERNOON WERE HELPING TO PRODUCE A SIGNIFICANT TEMPERATURE GRADIENT ACROSS THE MID STATE. AT 300 PM...TEMPERATURES RANGED FROM THE UPPER 60S AT CSV TO THE UPPER 80S OVER OUR MOST WESTERN COUNTIES. WITH SHOWERS DEPARTING OUR AREA, FROM THE PLATEAU, WE NOW TURN OUR EYES TO THE WEST, WHERE NEW THUNDERSTORMS WERE POPPING UP IN THE AFTERNOON HEAT, OVER SOUTHWESTERN KENTUCKY. THESE STORMS WERE ALSO OCCURRING ALONG THE EDGE OF A BAND OF MID-T0-UPPER LEVEL DRYING THAT EXTENDED FROM SOUTHERN PARTS OF INDIANA AND ILLINOIS, ACROSS SOUTHEAST MISSOURI INTO CENTRAL ARKANSAS. WITH THE POSSIBILITY OF DRY AIR ENTRAINMENT AT THE MID LEVELS, EXPECT SOME GUSTY DOWNBURSTS TO BE POSSIBLE WITH THESE STORMS AS THEY ADVANCE INTO NORTHWESTERN MIDDLE TENNESSEE LATE THIS AFTERNOON AND EVENING. AFTER THE INITIAL CONVECTION THIS EVENING, THAT DEVELOPS MAINLY OVER THE NORTHWEST, BELIEVE WE WILL SEE MORE THUNDERSTORM DEVELOPMENT LATER TONIGHT, AS UPPER TROUGH DEEPENS OVER THE OHIO RIVER VALLEY, ENERGIZING THE SLEEPY STATIONARY FRONT JUST WEST OF PADUCAH, AND BRINGING IT EASTWARD AS A COLD FRONT. EXPECT THE COLD FRONT TO BE NEAR A BWG-BNA-WAYNESBORO LINE BY 12Z FRIDAY, PUSHING TO NR A MSL-LIVINGSTON LINE BY 18Z, AND OFF THE CUMBERLAND PLATEAU BY LATE FRIDAY AFTERNOON. SPC HAS ALL OF OUR AREA IN A SLIGHT RISK FOR SEVERE THUNDERSTORMS THROUGH 12Z FRIDAY, AS THE FRONT PUSHES IN, AND EXPECT TO SEE SIMILAR STORMS TO THE ONES WE HAD THIS MORNING...VERY WET AND JUICY (WITH TORRENTIAL DOWNPOURS) ALONG WITH THE POSSIBILITY FOR STRONG, GUSTY DOWNBURST WINDS. EXPECT SHOWERS AND STORMS TO FINALLY PUSH EAST OF THE MID STATE FRIDAY EVENING, WITH SEVERAL DAYS OF DRY AND AUTUMN-LIKE CONDITIONS TO FOLLOW OVER THE WEEKEND. EXPECT AFTERNOON DEW POINTS IN THE 50S BOTH SATURDAY AND SUNDAY, WITH DAYTIME HIGHS MAINLY IN THE MIDDLE 80S. MANY PLACES WILL LIKELY SEE LOW TEMPERATURES DROP INTO THE MID TO UPPER 50S SUNDAY MORNING. LONG TERM...AFTER OUR DRY SPELL OVER THE WEEKEND, EXPECT NORTHWEST FLOW TO BECOME MORE ZONAL, WITH TWO OR THREE UPPER LEVEL SHORTWAVES LIKELY TO TRAVERSE THE AREA NEXT WEEK. THE TIMING OF THESE IMPULSES, OF COURSE, IS VERY DIFFICULT. IT`S ALSO DIFFICULT TO KNOW HOW MUCH SHRA/TSRA ACTIVITY EACH ONE WITH BRING WITH IT. THEREFORE, HAVE PAINTED POPS WITH A BROAD BRUSH FOR MOST OF NEXT WEEK, WITH A 20% POP MAKING REPEATED ONSTAGE APPEARANCES. TEMPERATURES WILL WARM BACK TO AROUND 90 DEGREES OR IN THE LOWER 90S FOR AREAS WEST OF THE CUMBERLAND PLATEAU, WITH TEMPS FORECAST TO BE MAINLY IN THE MIDDLE 80S ALONG THE PLATEAU ITSELF. && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 31
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
345 AM EDT FRI AUG 10 2012 .SYNOPSIS... A STRONG UPPER LEVEL TROUGH WILL PASS INTO THE GREAT LAKES TODAY...DRAGGING A COLD FRONT ACROSS THE REGION THIS EVENING. THIS WILL RESULT IN ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND EVENING...WITH A FEW STORMS BECOMING STRONG TO SEVERE. ONCE THE COLD FRONT MOVES EAST OF THE AREA LATE TONIGHT...HIGH PRESSURE WILL BUILD IN...BRINGING COOLER AND DRIER AIR IN FOR THE REMAINDER OF THE WEEKEND AND THE EARLY PART OF NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 315 AM EDT FRIDAY... MAIN CONCERN TODAY WITH THE DEGREE OF POSSIBLE RENEWED CONVECTION LATER ON AS THE UPPER LOW TO THE NW PROPELS A STRONG COLD FRONT TO ALONG THE WESTERN SLOPES THIS EVENING AND EAST OF THE BLUE RIDGE OVERNIGHT. AGAIN ONE OF THE MAIN FACTORS IS WITH JUST HOW MUCH DEEP INSTABILITY CAN BE GENERATED THIS AFTERNOON IN THE WAKE OF THE CURRENT MVC THAT WILL EXIT THE CWA BY DAYBREAK. THIS FEATURE AND ITS CONVECTION HAVE BASICALLY REMOVED ANY LINGERING CAPE FROM THU EVENING AND WILL NEED A PERIOD OF STRONG HEATING TO REGENERATE ENOUGH INSTABILITY FOR A MORE WIDESPREAD SEVERE THREAT. LATEST FCST SOUNDINGS DO SHOW WIND FIELDS STRENGTHENING/BACKING ALOFT AHEAD OF THE UPSTREAM TROF THRU THIS EVENING SUGGESTING POTENTIAL FOR BANDS OF DEEPER CONVECTION THAT MAY EVENTUALLY LINE UP ESPCLY OUT EAST BY THIS EVENING. HOWEVER LATEST MODELS REMAIN SPREAD ACROSS THE BOARD WITH TIMING AND LOCATION ISSUES OF PRE- FRONTAL LIFT PER SLOWNESS IN INITIALIZING WITH THE CURRENT REMNANT MCS ATTM. APPEARS BEST SOLUTION IS TO LEAN TOWARD THE LATEST HRRR AND GO WITH DEVELOPMENT OF MULTICELLULAR BANDS OVER THE MOUNTAINS BY EARLY AFTERNOON PER UNIDIRECTIONAL FLOW AND THETA-E RIDGING...WITH THIS COVERAGE OR ANOTHER LINE GRADUALLY ORGANIZING UPON HEADING EAST INTO BETTER INSTABILITY OUT EAST THRU EARLY EVENING. THIS AGAIN BASED ON AT LEAST SOME HEATING AS SUGGESTED BY THE LATEST NAM WHICH BREAKS OPEN THE MID DECK LATER THIS MORNING AHEAD OF THE BOUNDARY. THUS HAVE ADJUSTED POPS TO REFLECT A BREAK IN COVERAGE PER WEAK SUBSIDENCE IN BEHIND THE PASSING VORT EARLY THIS MORNING...INCREASING TO LIKELY/CAT POPS WEST EARLY/MID AFTERNOON...THEN TRANSLATING EAST INTO EARLY THIS EVENING. THINK COVERAGE MOVING ENOUGH TO PRECLUDE A FLASH FLOOD WATCH BUT CERTAINLY A WIND THREAT GIVEN DECENT FCST DCAPES WHICH WILL COVER IN THE HWO PER SWODY1 SLIGHT RISK. WILL STAY ON THE WARM SIDE OF MOS TEMPS TODAY AS THINKING SOME INSOLATION BUT IF CLOUDS HOLD AND CONVECTION FASTER THEN HIGH BUST POTENTIAL REMAINS. EXPECT MAIN AXIS OF CONVECTION TO BE EAST OF THE MOUNTAINS THIS EVENING AND MAY TAKE SOME TIME TO EXIT THE PIEDMONT AS ANOTHER WEAK IMPULSE RIDES UP THE FRONT. THINK SEVERE POTENTIAL LIMITED BEHIND THE INIT WAVE OF STORMS BUT LINGERING HEAVY RAIN THREAT COULD PERSIST WHILE SHOWERS BECOME WIDELY SCATTERED OR END BEHIND THE BOUNDARY OVER THE MOUNTAINS OVERNIGHT. THEREFORE DID DECREASE POPS A BIT FASTER WEST THINKING CONVECTION WILL HELP TAKE DEEP MOISTURE TO THE EAST LATE...BUT LIKELY STILL LOTS OF CLOUDS AS THE UPPER FLOW REMAINS SW AND PARALLEL TO THE SFC FRONT. MAIN PUSH OF 85H COOL ADVECTION WILL STILL BE WEST OF THE BLUE RIDGE LATE TONIGHT SO KEEPING TEMPS WARMER OUT EAST AND NOT QUITE AS COOL MOUNTAINS PER CLOUD COVER. OTRW RANGE OF LOWS FROM AROUND 60 FAR WEST TO 65-70 SE LOOKS BEST. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 300 AM EDT FRIDAY... SHORTWAVE PIVOTS ACROSS THE CENTRAL APPALACHIANS SATURDAY AFTERNOON. THIS WILL KEEP THE THREAT OF SHOWERS AND ISOLATED THUNDERSTORMS GOING IN THE EAST WITH COOL POOL ALOFT. 8H TEMPS COOL TO +14C...SO WITH SOME CLOUD COVER FROM THE COLDER AIR ALOFT...EXPECT HIGHS CLOSE TO THE ADJMETBC WITH READINGS FROM THE MID 70S IN THE MOUNTAINS TO THE MID 80S IN THE SOUTHEAST. DRIER AIR WILL FINALLY WORKS IN FROM THE NORTHWEST SATURDAY NIGHT INTO SUNDAY WITH DEWPOINTS DROPPING INTO THE UPPER 40S/LOWER 50S IN THE HIGHER ELEVATIONS WITH MID 50S VALLEYS. THE PIEDMONT COULD SEE SOME 50S DEWPOINTS BUT HARD TO DISPLACE THE HUMID AIRMASS ACROSS THE CAROLINAS AS THE FLOW ALOFT STAYS WSW. PLAYED LOW TEMPERATURES SATURDAY NIGHT FROM THE LOWER 50S IN THE MOUNTAINS TO THE LOWER 60S IN THE EAST. ON SUNDAY...TEMPERATURES MODERATE WITH WSW FLOW AND MORE SUNSHINE. HEIGHTS/8H TEMPERATURES INCREASE AGAIN...HIGHS SUNDAY RETURNING TO AROUND 80 DEGREES IN THE MOUNTAINS TO THE UPPER 80S IN THE SOUTHEAST. LEANED TOWARDS THE ECMWFBC FOR SUNDAY NIGHT LOW TEMPERATURES WITH VALUES FROM THE MID 50S IN THE WEST TO THE MID 60S IN THE EAST. && .LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 400 PM EDT THURSDAY... DRIER AIRMASS WILL BE DISPLACED DURING THIS PERIOD AS THE FRONT FROM THE SHORT TERM PERIOD STALLS ACROSS THE CAROLINAS/TN VALLEY THEN SHIFTS SLOWLY NORTH BY TUESDAY AS ANOTHER WAVE OF LOW PRESSURE SHIFTS ACROSS IT FROM THE LOWER MISSOURI VALLEY INTO THE VA TIDEWATER FROM MON-TUE. THIS FRONT WILL BE CLOSE ENOUGH THAT SHOWER/TSRA CHANCES INCREASE AGAIN BY TUESDAY. ONCE THE SHORTWAVE/ASSOCIATED SFC LOW PASS TUESDAY AFTERNOON...WEAK HIGH PRESSURE WILL PUSH THE FRONT BACK SOUTH INTO THE GA/SC BY WEDNESDAY AND THE AIRMASS DRIES OUT SOME...BUT THE UPPER TROUGH IS NOT AS DEEP AS THIS WEEKENDS. OVERALL...THE TEMPS NEXT WEEK WILL AVERAGE 80S/LOWER 90S FOR HIGHS AND 60S FOR LOWS. && .AVIATION /08Z FRIDAY THROUGH TUESDAY/... AS OF 105 AM EDT FRIDAY... AXIS OF CONVECTION CONTINUES TO WORK NE JUST EAST OF THE BLUE RIDGE ATTM AND EXPECT THIS COVERAGE TO AFFECT KDAN AND KLYH FOR A FEW MORE HOURS WITH MVFR/IFR CONDITIONS. ELSW A FEW ADDED ISOLATED SHRA POSSIBLE OVERNIGHT OTRW LOOKING AT MAINLY VFR BEFORE FOG FORMATION SETS IN PENDING JUST HOW FAST THE MID DECK CANOPY ERODES BY DAYBREAK. APPEARS THE NORMALLY FOGGY LOCATIONS SUCH AS KLWB WILL SEE IFR/LIFR BY DAWN WITH MVFR/IFR POSSIBLE AT KBCB. EASTERN AREAS MAY ALSO SEE SOME MVFR FOG DEVELOP IN THE WAKE OF THE CURRENT SHRA/TSRA SO INCLUDING SOME LOWER VSBYS/CIGS EARLY FRIDAY. SHOWER AND THUNDERSTORMS WILL INCREASE LATE FRIDAY MORNING AND EARLY AFTERNOON AS A DEEP UPPER LEVEL TROUGH APPROACHES THE AREA...WITH AN ASSOCIATED COLD FRONT ENTERING THE WESTERN PART OF THE FORECAST AREA TOWARD THE END OF THE TAF PERIOD. WILL BE LOOKING AT A FEW STRONG STORMS TO START THE AFTERNOON...AND EXPECT THAT THESE STORMS WILL FORM INTO A LINE OR TWO JUST AHEAD OF THE COLD FRONT AS IT ENTERS THE PIEDMONT REGION DURING EARLY EVENING. THUNDERSTORM ACTIVITY IS EXPECTED TO END ACROSS THE AREA AS THE FRONT EXITS TO THE EAST DURING LATE EVENING...AT WHICH POINT DRIER AIR ASSOCIATED WITH HIGH PRESSURE WILL RESULT IN VFR CONDITIONS HEADING INTO THE EARLY PART ON NEXT WEEK. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...JH/NF NEAR TERM...JH SHORT TERM...KK LONG TERM...WP AVIATION...JH/KM/NF
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
445 AM PDT FRI AUG 10 2012 ...UPDATED AVIATION DISCUSSION... .SYNOPSIS... A HOT AIR MASS WILL REMAIN IN PLACE THROUGH THE WEEKEND DUE TO HIGH PRESSURE OVER THE REGION. ISOLATED THUNDERSTORMS ARE POSSIBLE FOR THE VENTURA AND LOS ANGELES COUNTY MOUNTAINS AND ANTELOPE VALLEY AS MONSOONAL MOISTURE OVER THE AREA. A TROUGH OF LOW PRESSURE IS EXPECTED TO COOL TEMPERATURES CLOSER TO NORMAL EARLY NEXT WEEK. && .SHORT TERM (TODAY-SUNDAY)... STRONG HIGH PRESSURE ALOFT REMAINS OVER THE REGION THIS MORNING AS SOUTHEAST FLOW ALOFT ESTABLISHES. AT THE SURFACE...A THERMAL TROUGH REMAIN OFFSHORE SOUTH OF POINT CONCEPTION AND IS SHIFT ONSHORE NORTH OF POINT CONCEPTION. WITH THE SURFACE TROUGH OFFSHORE...ANOTHER HOT DAY IS ON TAP SOUTH OF POINT CONCEPTION. NORTH OF POINT CONCEPTION...INCREASING ONSHORE GRADIENTS SHOULD PROVIDE SOME COOLING TODAY. AN EXCESSIVE HEAT WARNING REMAINS IN EFFECT FOR THE LOS ANGELES AND VENTURA COUNTY VALLEYS AND MOUNTAINS AND THE SANTA BARBARA COUNTY MOUNTAINS THROUGH THIS EVENING. HEAT INDEX VALUES WILL BE NEAR DANGEROUS LEVELS AGAIN TODAY OVER THESE AREAS. THE MAIN CONCERN FOR THE TEMPERATURE FORECAST IS THE INCREASING MID-LEVEL MOISTURE OCCURRING THIS MORNING. SOME COOLING CLOUD TOPS ARE OCCURRING THIS MORNING AND THE CLOUD MASS IS EXPANDING OVER THE AREA THIS MORNING. THIS COULD BE THE MAIN PROBLEM FOR TODAY BEING THE WARMEST DAY OF THE WEEK AS PREVIOUSLY ADVERTISED. IN ADDITION...SURFACE GRADIENTS TRENDS ARE STARTING TO REVERSE AND BECOME MORE STRONGLY ONSHORE. WITH THESE TWO FACTORS IN MIND...TEMPERATURES WERE COOLED SLIGHTLY AS THE AIR MASS COULD COOL SLIGHTLY AS A RESULT. THE CLOUD MASS OVER LOS ANGELES COUNTY THIS MORNING IS BEING MONITORED CLOSELY WITH MODEL SOLUTIONS HANDLING THE MOISTURE REASONABLY...BUT THE THERMAL PATTERN ALOFT SEEMS QUESTIONABLE. GOES SATELLITE IMAGERY PLACES CLOUDS TOPS BETWEEN 20 AND 30 KFT THIS MORNING WITH CLOUD TOPS COOLING...YET MODEL SOLUTIONS ALL INDICATE TEMPERATURES INCREASING ALOFT. SOME CONCERN IS PLACED WITH CLOUD MASS POSSIBLY BECOMING CONVECTIVE AS THE MORNING PROGRESSES AND POPS NEEDING TO BE ADDED FOR THE COASTS AND VALLEYS FOR TODAY. RAP MODEL SOLUTIONS SUGGEST SOME MID-LEVEL CAPE DEVELOPING LATER THIS MORNING AND SOME POSITIVE OMEGA OCCURRING IN THE LOWER LEVELS OF THE ATMOSPHERE. FOR NOW...THE BEST APPROACH IS TO MONITOR THE SITUATION FOR THE POSSIBILITY OF SHOWERS DEVELOPING THEN UPDATE AS NECESSARY. THE AIR MASS WILL CONTINUE TO MOISTEN THROUGH THE WEEKEND AND COOL AS A MONSOONAL FLOW PATTERN MATURES OVER THE AREA. THE CHANCES FOR SHOWERS AND THUNDERSTORMS WILL INCREASE SLIGHTLY FOR SATURDAY AS MOISTURE INCREASES OVER THE AREA. THE HEAT WAVE WILL SEE SOME REPRIEVE BUT IT WILL REMAIN QUITE WARM UNTIL SOUTHWEST FLOW ALOFT ESTABLISHES OVER THE AREA EARLY NEXT WEEK. .LONG TERM (MONDAY-THURSDAY)... SOUTHWEST FLOW ALOFT SHOULD ESTABLISH OVER THE AREA BETWEEN SUNDAY AND MONDAY AND BRING A COOLER AND DRIER AIR MASS TO THE AREA. ONSHORE FLOW SHOULD INCREASE AND ALLOW FOR A STRONGER SEA BREEZE EACH DAY...WITH A COOLING TREND PERSISTING INTO THURSDAY. SOME LOWER VALLEY INTRUSION OF THE MARINE LAYER CLOUDS IS POSSIBLE BETWEEN MONDAY NIGHT AND THURSDAY. && .AVIATION...10/1145Z. HIGH CONFIDENCE FOR VFR CONDITIONS ARE EXPECTED AT ALL INLAND TERMINALS. AT COASTAL TERMINALS SOUTH OF POINT CONCEPTION...THERE IS A 30 PERCENT CHANCE OF LIFR CONDITIONS AT COASTAL TERMINALS BETWEEN 12Z AND 16Z. NORTH OF POINT CONCEPTION...VLIFR TO LIFR CONDITIONS WILL PERSIST THROUGH AT LEAST 14Z...THEN GRADUALLY IMPROVE TO VFR THROUGH 17Z. KLAX...VFR CONDITIONS ARE EXPECTED THROUGHOUT THE PERIOD. THERE IS A 20 PERCENT CHANCE OF VLIFR TO LIFR CONDITIONS BETWEEN 12Z AND 15Z. KBUR...VFR CONDITIONS ARE EXPECTED THROUGHOUT THE PERIOD WITH NO WIND ISSUES. && .LOX WATCHES/WARNINGS/ADVISORIES... EXCESSIVE HEAT WARNING (SEE LAXNPWLOX). SMALL CRAFT ADVISORY (SEE LAXMWWLOX). SPECIAL WEATHER STATEMENT (SEE LAXSPSLOX). && $$ PUBLIC...HALL AVIATION...CK SYNOPSIS...B/HALL WWW.WEATHER.GOV/LOSANGELES
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
421 AM PDT FRI AUG 10 2012 .SYNOPSIS... A HOT AIR MASS WILL REMAIN IN PLACE THROUGH THE WEEKEND DUE TO HIGH PRESSURE OVER THE REGION. ISOLATED THUNDERSTORMS ARE POSSIBLE FOR THE VENTURA AND LOS ANGELES COUNTY MOUNTAINS AND ANTELOPE VALLEY AS MONSOONAL MOISTURE OVER THE AREA. A TROUGH OF LOW PRESSURE IS EXPECTED TO COOL TEMPERATURES CLOSER TO NORMAL EARLY NEXT WEEK. && .SHORT TERM (TODAY-SUNDAY)... STRONG HIGH PRESSURE ALOFT REMAINS OVER THE REGION THIS MORNING AS SOUTHEAST FLOW ALOFT ESTABLISHES. AT THE SURFACE...A THERMAL TROUGH REMAIN OFFSHORE SOUTH OF POINT CONCEPTION AND IS SHIFT ONSHORE NORTH OF POINT CONCEPTION. WITH THE SURFACE TROUGH OFFSHORE...ANOTHER HOT DAY IS ON TAP SOUTH OF POINT CONCEPTION. NORTH OF POINT CONCEPTION...INCREASING ONSHORE GRADIENTS SHOULD PROVIDE SOME COOLING TODAY. AN EXCESSIVE HEAT WARNING REMAINS IN EFFECT FOR THE LOS ANGELES AND VENTURA COUNTY VALLEYS AND MOUNTAINS AND THE SANTA BARBARA COUNTY MOUNTAINS THROUGH THIS EVENING. HEAT INDEX VALUES WILL BE NEAR DANGEROUS LEVELS AGAIN TODAY OVER THESE AREAS. THE MAIN CONCERN FOR THE TEMPERATURE FORECAST IS THE INCREASING MID-LEVEL MOISTURE OCCURRING THIS MORNING. SOME COOLING CLOUD TOPS ARE OCCURRING THIS MORNING AND THE CLOUD MASS IS EXPANDING OVER THE AREA THIS MORNING. THIS COULD BE THE MAIN PROBLEM FOR TODAY BEING THE WARMEST DAY OF THE WEEK AS PREVIOUSLY ADVERTISED. IN ADDITION...SURFACE GRADIENTS TRENDS ARE STARTING TO REVERSE AND BECOME MORE STRONGLY ONSHORE. WITH THESE TWO FACTORS IN MIND...TEMPERATURES WERE COOLED SLIGHTLY AS THE AIR MASS COULD COOL SLIGHTLY AS A RESULT. THE CLOUD MASS OVER LOS ANGELES COUNTY THIS MORNING IS BEING MONITORED CLOSELY WITH MODEL SOLUTIONS HANDLING THE MOISTURE REASONABLY...BUT THE THERMAL PATTERN ALOFT SEEMS QUESTIONABLE. GOES SATELLITE IMAGERY PLACES CLOUDS TOPS BETWEEN 20 AND 30 KFT THIS MORNING WITH CLOUD TOPS COOLING...YET MODEL SOLUTIONS ALL INDICATE TEMPERATURES INCREASING ALOFT. SOME CONCERN IS PLACED WITH CLOUD MASS POSSIBLY BECOMING CONVECTIVE AS THE MORNING PROGRESSES AND POPS NEEDING TO BE ADDED FOR THE COASTS AND VALLEYS FOR TODAY. RAP MODEL SOLUTIONS SUGGEST SOME MID-LEVEL CAPE DEVELOPING LATER THIS MORNING AND SOME POSITIVE OMEGA OCCURRING IN THE LOWER LEVELS OF THE ATMOSPHERE. FOR NOW...THE BEST APPROACH IS TO MONITOR THE SITUATION FOR THE POSSIBILITY OF SHOWERS DEVELOPING THEN UPDATE AS NECESSARY. THE AIR MASS WILL CONTINUE TO MOISTEN THROUGH THE WEEKEND AND COOL AS A MONSOONAL FLOW PATTERN MATURES OVER THE AREA. THE CHANCES FOR SHOWERS AND THUNDERSTORMS WILL INCREASE SLIGHTLY FOR SATURDAY AS MOISTURE INCREASES OVER THE AREA. THE HEAT WAVE WILL SEE SOME REPRIEVE BUT IT WILL REMAIN QUITE WARM UNTIL SOUTHWEST FLOW ALOFT ESTABLISHES OVER THE AREA EARLY NEXT WEEK. .LONG TERM (MONDAY-THURSDAY)... SOUTHWEST FLOW ALOFT SHOULD ESTABLISH OVER THE AREA BETWEEN SUNDAY AND MONDAY AND BRING A COOLER AND DRIER AIR MASS TO THE AREA. ONSHORE FLOW SHOULD INCREASE AND ALLOW FOR A STRONGER SEA BREEZE EACH DAY...WITH A COOLING TREND PERSISTING INTO THURSDAY. SOME LOWER VALLEY INTRUSION OF THE MARINE LAYER CLOUDS IS POSSIBLE BETWEEN MONDAY NIGHT AND THURSDAY. && .AVIATION...10/0625Z. VFR CONDITIONS ARE EXPECTED AT ALL INLAND TERMINALS. AT COASTAL TEMRINALS SOUTH OF POINT CONCEPTION...THERE IS A CHANCE OF LIFR CONDITIONS AT COASTAL TERMINALS BETWEEN 08Z AND 16Z. NORTH OF POINT CONCEPTION...VLIFR TO LIFR CONDITIONS WILL PERSIST THROUGH AT LEAST 14Z...THEN GRADUALLY IMPROVE TO VFR THROUGH 17Z. KLAX...VFR CONDITIONS ARE EXPECTED THROUGHOUT THE PERIOD. THERE IS A 20 PERCENT CHANCE OF VLIFR TO LIFR CONDITIONS BETWEEN 12Z AND 15Z. KBUR...VFR CONDITIONS ARE EXPECTED THROUGHOUT THE PERIOD WITH NO WIND ISSUES. && .LOX WATCHES/WARNINGS/ADVISORIES... EXCESSIVE HEAT WARNING (SEE LAXNPWLOX). SMALL CRAFT ADVISORY (SEE LAXMWWLOX). SPECIAL WEATHER STATEMENT (SEE LAXSPSLOX). && $$ PUBLIC...HALL AVIATION...HALL/KAPLAN SYNOPSIS...B/HALL WWW.WEATHER.GOV/LOSANGELES
AREA FORECAST DISCUSSION
NWS TAUNTON MA
1015 AM EDT FRI AUG 10 2012 .SYNOPSIS... LOW PRESSURE PASSING WEST OF NEW ENGLAND BRINGS A HIGH LIKELIHOOD OF SHOWERS/THUNDERSTORMS TODAY THROUGH SATURDAY. SOME OF THE THUNDERSTORMS MAY CONTAIN VERY HEAVY DOWNPOURS IN THE TROPICAL AIR MASS. A FEW THUNDERSTORMS MAY ALSO PRODUCE STRONG WIND GUSTS. DRIER AND LESS HUMID AIR RETURNS FOR LATE THIS WEEKEND INTO EARLY NEXT WEEK. ANOTHER LOW PRESSURE WITH ASSOCIATED WARM AND COLD FRONTS WILL IMPACT OUR REGION DURING THE MIDDLE OF NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 10 AM UPDATE... WATCHING THE SITUATION CLOSELY. S NEW ENGLAND ENVELOPED IN A VERY TROPICAL AIRMASS AT THE SFC WITH DWPTS IN THE LOW 70S. LATEST SATELLITE EXHIBITS A FEW BREAKS IN THE MID-LVL CLOUDS...BUT BENEATH WE ARE ALREADY SEEING N-S CLOUD STREETS INDICATIVE OF AN UNSTABLE ENVIRONMENT. SPC MESOANALYSIS HIGHLIGHTS INCREASING INSTABILITY OF 1-2K J/KG ACROSS THE RGN...BUT THE BETTER 0-6 KM BULK SHEAR LAGS. WHILE LIKELY SHOWERS AND THUNDERSTORMS WILL INCREASE IN AREAL CONVERAGE WITH THE HEATING OF THE DAY...THE BETTER THREAT FOR SEVERE WX AND HEAVY RAINS MAY NOT BE UNTIL LATER THIS AFTN INTO EVNG SUBSEQUENT WITH A SHRTWV DISTURBANCE AND BETTER DEEP LYR SHEAR /30-40 KTS/ ROUNDING THRU THE BROADER TROF /PRESENTLY THE SHRTWV IS LOCATED ACROSS THE CAROLINA RGN...LIFTING NEWD AND INVIGORATING ACTIVITY OVER THE DELMARVA PENINSULA/. MID-LVL LAPSE RATES APPEAR MARGINAL TODAY. ITS IMPORTANT TO NOTE THAT ANY STORMS WITHIN THE VERY MOIST AND TROPICAL AIRMASS WILL HAVE THE POSSIBILITY OF DROPPING AN INCH OF RAIN IN 30 MINUTES OR LESS. PWATS ADVERTISED VIA SPC MESOANALYSIS ALREADY THIS MORNING ARE AROUND 1.75 INCHES AND ANTICIPATING AN INCREASE TOWARDS THE LATER HALF OF THE DAY ALONG AND AHEAD OF THE ROUNDING SHRTWV DISTURBANCE. BUT THERE IS SOME MID-LVL DRYING CONSEQUENTIAL FROM AIR FLOW ORIGINATING FROM THE W ATLANTIC RIDGE /SEE THE 12Z UPR AIR ANALYSIS FROM CHATHAM AND NEW YORK VERSUS ALBANY/. SUCH DRYING MAY IMPACT PWATS. STILL DO NOT BELIEVE THE FLOOD THREAT WILL BE LESSENED. SO SUMMARIZING...WITH THE SEVERE WX THREAT EXPECTING GUSTY WINDS AND PSBL LARGE HAIL WITH A FEW OF THE STORMS. AS FOR FLOODING... ANTICIPATE HEAVY RAINS WITHIN A SHORT PD OF TIME RESULTING IN URBAN AND SMALL STREAM IMPACTS. STORMS LIKELY TO TRAIN ACROSS RGNS RESULTING IN ROUNDS OF HEAVY RAINS. OTHERWISE...SHORT-RANGE MDL SOLNS ARE NOT IMPRESSIVELY HANDLING THE MORNING SITUATION WELL...THE 0Z CANADIAN/ECMWF ARE SEEMINGLY DOING A GOOD JOB. THE MESO-RUC AND HRRR ARE SHOWING SOME ISSUES WITH THE MORNING ACTIVITY. ALL FCST MDLS DO TREND AN AREA OF HEAVY RAIN PROGRESSING NEWD FROM THE MID-ATLANTIC INTO S NEW ENGLAND COLLOCATED WITH THE MAIN SHRTWV WITH IMPINGING S/SWLY LOW-MID LVL LLJ TO THE REAR. THE EXACT LOCALE OF HEAVIEST RAINS IS STILL UNDER SCRUTINY...BUT IT LOOKS LIKE HEAVY RAIN AND POTENTIAL FLOODING WILL CONTINUE OVRNGT INTO THE MORNING PD. TEMPS WILL BE A TAD COOLER /80 TO 85F/ THAN PREVIOUS DAYS AS CLOUD COVER WILL BE THE MAIN FACTOR. HOWEVER DEWPOINTS ARE STILL WELL INTO THE LOW 70 ALLOWING THE ATMOSPHERE TO BE QUITE MUGGY. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/... FRIDAY NIGHT... EXPECT CONVECTION TO CONTINUE PAST SUNSET AS THERE IS SOME ELEVATED INSTABILITY ACROSS THE AREA. STORM STRUCTURE HOWEVER WILL BE MORE OF A CLUSTER WITH POSSIBLE BOWING SEGMENTS...DEEPENING ON THE AMOUNT OF HEATING DURING THE DAY. WINDS WILL BACK TO THE SOUTHWEST BY THE EVENING HOURS BLOCKING THE TROPICAL FEED FOR THE WESTERN ZONES. MAIN FOCUS FOR THE OVERNIGHT PERIOD IS THE WARM FRONT THAT DEVELOPS ACROSS THE MID-ATLANTIC IN WHICH WILL MOVE ACROSS SNE OVERNIGHT. EXPECT A LLJ TO DEVELOP BEHIND THE FRONT AND THIS COMBINED WITH SAID FRONT AND HIGH PWATS BELIEVE A GOOD SOAKING WILL TAKE PLACE. APPEARS THAT THE EASTERN PORTION OF THE REGION WILL SEE THE HIGHEST AMOUNTS OF QPF AS PWATS ARE NEAR 2.5 INCHES. EXPECT PRECIP WITH PERHAPS EMBEDDED THUNDER WILL CONTINUE WELL INTO OVERNIGHT PERIOD AND MOVE IN A MORE SOUTH TO NORTH MANNER. IF ANY STORMS DEVELOP ALONG THE FRONT THEN THE POTENTIAL FOR HEAVY DOWNPOURS AND FLASH FLOODING SHOULD BE EXPECTED. SATURDAY... UPPER LEVEL LOW OVER THE GREAT LAKES WILL CONTINUE TO DRIFT NORTHWARD INTO QUEBEC. THIS WILL PUSH A COLD FRONT ACROSS WESTERN NEW ENGLAND. BELIEVE SHOWERS WILL CONTINUE INTO SATURDAY BUT EXACT PLACEMENT IS A LITTLE UNCERTAIN. BELIEVE THE WEST HALF OF THE AREA HAS THE BEST CHANCE SINCE THEY ARE CLOSER TO THE FRONT. THE POTENTIAL FOR STRONG OR SEVERE STORMS IS LIMITED ONCE AGAIN TO THE AMOUNT OF DAYTIME HEATING. BELIEVE STRONG STORMS AREA LIKELY WITH GUSTY WINDS AND HEAVY RAIN BEING THE MAIN FOCUS. STORM STRUCTURE SHOULD BE MORE MULTI-CELLULAR IN NATURE AND SHOULD EXPECT A LEAST SOME STRONG STORMS. HOWEVER THE POTENTIAL OF SEVERE IS NOT OUT OF THE QUESTION AS BULK SHEAR VALUES ARE 30KTS WITH MARGINAL LAPSE RATES. TEMPS WILL CREEP BACK INTO THE MID TO UPPER 80S AS 850MB TEMPS ARE BETWEEN 16-18C . MUGGY CONDITIONS ARE EXPECTED AS DEWS ARE IN THE LOW 70S. SATURDAY ALSO LOOKS A TAD ON THE BREEZY SIDE AS SOUTHERLY WINDS LOOK TO GUST NEAR 20 MPH ALONG THE SOUTH COAST. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... BIG PICTURE... SERIES OF SHORT WAVE TROFS AMPLIFY WHAT LOOKS TO BE A MEAN LONG WAVE TROF POSITION JUST W OF NEW ENGLAND. THE AMPLITUDE AND POSITIONING OF THESE SHORT WAVE TROFS PROVIDE A FOCUS FOR CONVECTION AS WELL AS OPEN THE DOOR TO TROPICAL MOISTURE. HAVE LEFT OVER SHOWERS AND TSTMS SAT EVENING AND THEN ANOTHER BOUT WITH A WARM FRONT LATE TUE AND COLD FRONT WED AFTERNOON AND EVE. STILL ANOTHER BOUT OF CONVECTION AND TROPICAL MOISTURE POSSIBLE AT THE END OF THE WEEK. SAT NIGHT...LEFT OVER SHOWERS AND EMBEDDED TSTMS MAY PERSIST MUCH OF THE EVENING IN THE EAST. POTENTIAL REMAINS FOR SOME TSTMS TO PRODUCE VERY HEAVY DOWNPOURS IN EASTERN SECTIONS WHERE PWATS REMAIN NEAR OR ABOVE 2 INCHES. SUN...THINK IT WILL BE DRY. TEMPS SHOULD REBOUND TO MID 80S WITH MOSTLY SUNNY SKIES. SUN NIGHT THRU MON NIGHT...LOOKS TO BE DRY. MON HIGH TEMP SHOULD AGAIN BE IN THE MID 80S FOR MOST LOCATIONS...WHILE THE LOWER DEWPOINTS ALLOW FOR COOLER OVERNIGHT TEMPS. TUE/TUE NIGHT...WARMER AND MORE HUMID AIR BEGINS TO RETURN LATE TUE. RISK OF SHOWERS/TSTMS WITH WARM FRONT LATE TUE INTO TUE NIGHT. ALTHOUGH SOME DIFFERENCES IN TIMING AND PRECISE CONFIGURATION...ECMWF AND GFS PAINT A SIMILAR PICTURE. HAVE CHANCE POPS FOR LATE TUE AFTERNOON INTO TUE NIGHT. WED...DIFFERENCES IN THE MODELS BUT ALL SUGGEST THAT A FAIRLY PRONOUNCED SHORT WAVE TROF AND SURFACE COLD FRONT WILL MOVE THROUGH WED AFTERNOON WITH AN AIR MASS OF WEAK TO MODERATE INSTABILITY. HAVE CHANCE POPS IN THE GRIDS. THU...LOOKS TO BE DRY WITH TEMPERATURES NEAR OR SLIGHTLY ABOVE NORMAL. && .AVIATION /14Z FRIDAY THROUGH TUESDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT MODERATE...30 PERCENT TO 60 PERCENT HIGH...GREATER THAN 60 PERCENT OVERVIEW...MODERATE CONFIDENCE. MVFR/IFR IN FOG AND STRATUS DEVELOPMENT THROUGH THE MORNING HOURS. BECOMING MAINLY VFR MOST LOCATIONS BETWEEN 13Z AND 15Z WITH AREAS OF MVFR/IFR CONDITIONS IN TSRA/SHRA BECOMING MORE NUMEROUS DURING THE AFTERNOON AND PERSISTING INTO SATURDAY. KBOS TAF...MODERATE CONFIDENCE. IFR CIG SHOULD IMPROVE AROUND OR SHORTLY AFT 13Z. SCT SHRA/TSRA LIKELY THIS AFTERNOON LASTING INTO SATURDAY WITH FREQUENT PERIODS OF MVFR CIGS/VSBYS AND A FEW BRIEF PERIODS OF IFR CIGS/VSBYS. KBDL TAF...MODERATE CONFIDENCE. MVFR CIG IN STRATUS EXPECTED TO IMPROVE TO VFR BETWEEN 13Z AND 14Z BUT INCREASING PERIODS OF MVFR CIGS/VSBYS IN TSRA/SHRA LATE THIS MORNING AND AFTERNOON. SCT TSRA/SHRA PERSTING INTO SATURDAY. CONFIDENCE ON TIMING LOW. OUTLOOK...SATURDAY NIGHT THROUGH TUESDAY... SAT NIGHT...LOW TO MODERATE CONFIDENCE. WIDESPREAD AREAS OF MVFR CIGS AND VSBYS IN SHOWERS AND EMBEDDED TSTMS. RAIN SHOULD END W TO E. SUN THROUGH TUE MORNING...HIGH CONFIDENCE OF VFR. TUE AFTERNOON/EVENING...MODERATE TO HIGH CONFIDENCE. MOSTLY VFR EXCEPT FOR MVFR CIGS/VSBYS IN ANY SHOWERS/TSTMS. && .MARINE... MODERATE TO HIGH CONFIDENCE. EXPECT SOUTH TO SOUTHWEST WINDS AND SEAS TO REMAIN BELOW SCA CRITERIA FOR TODAY. SHOWERS AND THUNDERSTORMS LIKELY ON THE WATERS THIS AFTERNOON THROUGH TONIGHT. A WARM FRONT WILL LIFT OVER THE WATERS DURING THE OVERNIGHT HOURS AIDING IN SEAS TO DEVELOP OVER 5 FT. HAVE ISSUED A SCA ALONG THE SOUTHERN WATERS WHERE 5FT SEAS ARE MOST LIKELY. LOW TO MODERATE PROBABILITY OF PATCHY...POSSIBLY DENSE...FOG DEVELOPING ON THE SOUTHERN WATERS TONIGHT. OUTLOOK...SATURDAY NIGHT THROUGH TUESDAY... MODERATE TO HIGH CONFIDENCE. SEAS OF 5 TO 6 FT LIKELY ACROSS EXPOSED SOUTH COAST WATERS THROUGH MOST OF SUNDAY BEFORE GRADUALLY SUBSIDING SUN NIGHT. TSTMS SAT EVENING MAY CONTAIN LOCALLY STRONG WIND GUSTS. QUIET WEATHER EXPECTED MONDAY THROUGH AT LEAST MOST OF TUE. && .HYDROLOGY... STRONG CHANCE OF LOCALIZED STREET FLOODING TONIGHT AND SAT WITH POSSIBILITY OF HIGHLY LOCALIZED FLASH FLOODING. AFTER COORDINATION WITH ADJACENT OFFICES...DECIDED TO HOLD OFF ON A FLASH FLOOD WATCH FOR NOW. SEE A RISK OF A TROPICAL FEED AIDED BY A LOW LEVEL JET IN AT LEAST A MARGINALLY UNSTABLE AIR MASS LATE TODAY THROUGH SATURDAY. BEST DYNAMICS REMAIN WELL W AND N OF REGION...BUT COULD ENCOUNTER SERIOUSLY EXCESSIVE RAINFALL IN ANY MESOSCALE BANDS THAT MAY SET UP. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 8 PM EDT SATURDAY FOR ANZ235-237-255-256. && $$ SYNOPSIS...DUNTEN/THOMPSON NEAR TERM...SIPPRELL/DUNTEN/THOMPSON SHORT TERM...DUNTEN LONG TERM...THOMPSON AVIATION...DUNTEN/THOMPSON MARINE...DUNTEN/THOMPSON HYDROLOGY...WFO STAFF
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
739 AM EDT FRI AUG 10 2012 .SYNOPSIS... A SLOW MOVING COLD FRONT WILL APPROACH THE FORECAST AREA FROM THE NORTHWEST THROUGH TONIGHT. THE FRONT WILL BECOME DIFFUSE SATURDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... MOISTURE WILL BE HIGH AHEAD OF THE SLOW MOVING COLD FRONT TODAY. EXPECT NUMEROUS SHOWERS AND THUNDERSTORMS MAINLY ASSOCIATED WITH THE H85 JET. THE RAP AND NAM INDICATE THE JET WILL MAINLY AFFECT THE FORECAST AREA EARLY TODAY. HOWEVER...CONTINUED HIGH MOISTURE AHEAD OF THE FRONT AND DIURNAL HEATING SUPPORTS ADDITIONAL SHOWERS AND THUNDERSTORMS LATER TODAY. LEANED TOWARD THE HIGHER GUIDANCE POPS. CLOUDINESS SHOULD LIMIT INSTABILITY. THE NAM/S FORECAST OF WEAK INSTABILITY APPEARS REASONABLE. IF SIGNIFICANT BREAKS AND STRONG HEATING DOES OCCUR THEN THERE WILL BE ENOUGH SHEAR FOR A FEW SEVERE THUNDERSTORMS. THE NAM SHOWS H85 WINDS NEAR 30 KNOTS MAINLY EARLY TODAY. BOTH THE NAM AND GFS SHOW RAINFALL AMOUNTS LESS THAN ONE- QUARTER OF AN INCH AND THESE GENERAL VALUES MAY BE CORRECT SINCE THE H85 JET MAXIMUM SHOULD BE NORTHEAST OF THE FORECAST AREA WHICH SHOULD LIMIT CONVERGENCE. HOWEVER...THERE WILL BE A THREAT OF VERY HEAVY RAIN BECAUSE OF PRECIPITABLE WATER VALUES AROUND 2 INCHES. ALSO...EXPECT 1000-500 MB THICKNESSES NEAR 574 WHICH IS THE PREFERRED VALUE FOR HEAVY RAIN IN AUGUST. USED THE GUIDANCE CONSENSUS FOR THE TEMPERATURE FORECAST. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/... MOISTURE AND CONVERGENCE ASSOCIATED WITH THE SLOW MOVING FRONT SUPPORTS SHOWERS AND THUNDERSTORMS TONIGHT. HOWEVER...INSTABILITY SHOULD BE LIMITED BY PREVIOUS CONVECTION AND DIURNAL COOLING. FORECASTED POPS OF LIKELY EARLY AND CHANCE LATE. THE NAM AND GFS SHOW THE FRONT LINGERING NEAR THE FORECAST AREA SATURDAY AND SATURDAY NIGHT BUT DEEPER MOISTURE APPEARS TO SHIFT A LITTLE EAST OF THE FORECAST AREA SATURDAY. THE NAM AND GFS MOS SUPPORT CHANCE POPS. USED THE GUIDANCE CONSENSUS FOR THE TEMPERATURE FORECAST THROUGH THE PERIOD. && .LONG TERM /SUNDAY THROUGH THURSDAY/... THE GFS SHOWS RIDGING TO THE SOUTH WITH LEE-SIDE TROUGHING IN THE FORECAST AREA DURING MUCH OF THE EXTENDED PERIOD. THE PATTERN SUPPORTS MAINLY DIURNAL SCATTERED THUNDERSTORMS. THE GFS ENSEMBLE MEANS SUPPORT SLIGHT CHANCE OF CHANCE POPS. EXPECT TEMPERATURES NEAR CLIMATOLOGY WITH LOWS IN THE LOWER 70S AND HIGHS IN THE LOWERS 90S. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/... LOW LEVEL JET AFFECTING THE AREA TODAY. LIFR/IFR CIGS ACROSS THE TAF SITES WILL LIFT TO MVFR THROUGH 14Z. COULD EVEN SEE A FEW SHOWERS EARLY THIS MORNING. EXPECT IMPROVING CONDITIONS BY 15Z-16Z. SOUTHWEST WINDS INCREASING TO 10-15KT BY MIDDAY WITH GUSTS NEAR 20 KNOTS. WIDESPREAD SHOWERS AND THUNDERSTORMS EXPECTED AGAIN THIS AFTERNOON INTO TONIGHT. EXTENDED AVIATION OUTLOOK...AN UNSETTLED WEATHER WILL PERSIST THROUGH SUNDAY. A COLD FRONT WILL MOVE SLOWLY THROUGH THE REGION FRIDAY THROUGH SUNDAY...THEREBY HOLDING A GOOD CHANCE FOR CONVECTION. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$ 07
AREA FORECAST DISCUSSION
NWS DES MOINES IA
620 AM CDT FRI AUG 10 2012 .SHORT TERM /TONIGHT/... MAIN FOCUS TODAY WILL BE ON CLOUD COVER AND TEMPERATURES FOR THE NEAR TERM. CWA TO REMAIN BENEATH CYCLONIC FLOW ALOFT...WITH WEAK CAA EXPECTED THROUGHOUT THE DAY. SOME LOW LEVEL MOISTURE RESULTING IN AN AREA OF LOW STRATUS CONTINUES TO DEVELOP OFF TO THE NORTHEAST OF THE CWA...WITH MODEL PROGGING THIS AREA OF STRATUS TO CONTINUE TO SPREAD/ADVECT INTO THE NORTHERN/EASTERN HALF OF THE CWA THROUGH SUNRISE. HRRR MODEL AND GOES-R WRF FORECAST BOTH HANDLING THE DEVELOPMENT OF THIS STRATUS WELL AND HAVE TAILORED SKY GRIDS TOWARD THE MODEL/SATELLITE PRODUCT TRENDS. EXPECT STRATUS TO LIFT/BREAK UP TOWARD MID/LATE MORNING ACROSS THE AREA...WITH RESULTANT MID LEVEL CU FIELD POSSIBLE. OTHERWISE MUCH DRIER TO MOVE INTO THE CWA WITH DEWPOINTS EXPECTED TO CONTINUE TO DROP TO AROUND 50 POSSIBLY EVEN INTO THE 40S WITH DRIER AIR MIXING DOWN AND ADVECTING INTO THE CWA IN NORTHERLY FLOW. WITH THE CAA...EXPECT TEMPS TO BE A FEW DEGREES COOLER THAN YESTERDAY WITH HIGHS MAINLY IN THE UPPER 70S TO AROUND 80. .LONG TERM /TONIGHT THROUGH THURSDAY/... CANADIAN HIGH PRESSURE MOVING INTO THE NORTHERN PLAINS EARLY THIS MORNING WITH TEMPERATURES DIPPING INTO THE LOW TO MID 40S OVER THE SOUTHEAST QUADRANT. THIS SYSTEM WILL SETTLE SOUTH TODAY AND BE STRETCHED OVER MUCH OF THE CENTRAL AND NORTHERN PLAINS TONIGHT. WHILE SOME MODIFICATION OF TEMPERATURES IS EXPECTED...SHOULD HAVE OVERNIGHT LOWS TONIGHT TOUCHING THE MID 40S AT A FEW LOCATIONS ACROSS THE NORTH AND INTO THE LOW TO MID 50S ELSEWHERE. THE CLOSED UPPER LOW THAT AFFECTED THE AREA ON THURSDAY WILL BE SHIFTING SLOWLY NORTHEAST ACROSS THE CENTRAL GREAT LAKES THROUGH MID DAY SATURDAY BEFORE GAINING STEAM SATURDAY NIGHT AS ANOTHER CLOSED UPPER LOW MOVES INTO CENTRAL CANADA. THIS WILL ALLOW A TRANSITION TO A MORE PROGRESSIVE NORTHWEST FLOW THAT WILL PERSIST THROUGH MUCH OF THE EXTENDED. A FAIRLY SIGNIFICANT SYSTEM WILL ARRIVE OVER THE PACIFIC NW LATE TODAY THEN MOVE ACROSS THE ROCKIES AND PRODUCE LEE SIDE CYCLOGENESIS INTO SATURDAY. SATURDAY WILL BE ANOTHER PLEASANT DAY AND EXPECT TEMPERATURES TO BE NEAR THE HIGH END OF GUIDANCE WITH DRY SFC AIR HEATING UP EFFICIENTLY. MID LEVEL THETA-E ADVECTION WILL COMMENCE SATURDAY NIGHT WITH THE INITIAL WAVE BEING SPENT ON MID LEVEL SATURATION. GULF MOISTURE WILL BREAK FREE AND BEGIN TO STREAM NORTHWARD SATURDAY NIGHT AS WELL WITH THE MOISTURE ADVECTION ARRIVING LATE AIDED BY AN INCREASING LOW LEVEL JET APPROACHING 40 KTS. THE COMBINATION OF THE MULTI LEVEL KINEMATICS AND THERMODYNAMICS WILL RESULT IN A DEEPLY FORCED SYSTEM WITH SHOWERS AND THUNDERSTORMS ARRIVING OVER THE WEST AFTER MIDNIGHT. ADDITIONAL CHANCES WILL CONTINUE SUNDAY AND SUNDAY NIGHT WITH AS THE SECOND SEGMENT OF THE UPPER LEVEL SYSTEM ARRIVES ALONG WITH THE SFC LOW REFLECTION. GENERAL AGREEMENT DEVELOPING THAT THE SFC LOW WILL SHIFT EAST ACROSS SOUTHERN IA AND WOULD ALLOW A PORTION OF THE WARM SECTOR TO LIFT INTO THE STATE. HIGH VARIABILITY POSSIBLE WITH HIGH TEMPERATURES ON SUNDAY WHERE HIGHS COULD STRUGGLE IN THE 60S UNDER INCREASING CLOUDS AND MORE PROLONGED PRECIPITATION WHILE RISING WELL INTO THE 80S SOUTH WHERE SOME SUN COULD BE POSSIBLE. THIS COULD LEAD TO AN AREA OF SFC BASED THUNDERSTORMS AND AN AREA WITH SEVERE POTENTIAL. PRECIPITATION CHANCES CONTINUE OVER MAINLY THE EAST SUNDAY EVENING BEFORE ENDING. THE REMAINDER OF THE EXTENDED IS HIGHLIGHTED BY SEVERAL IMPULSES RIPPLING THROUGH THE NW FLOW WHILE A DEEP UPPER LEVEL LOW DROPS INTO ALBERTA AND MANITOBA BY MID WEEK. OVERALL TIMING BECOMES DIFFICULT UNDER THESE SITUATIONS BUT GENERAL CONSENSUS IS A WEAK WAVE ARRIVING TUE NIGHT INTO WED WITH A MORE SIGNIFICANT SYSTEM IMPACTING THE AREA TOWARD THE END OF THE PERIOD AS ENERGY ASSOCIATED THE SOUTHERN CANADA SYSTEM ARRIVES. && .AVIATION...10/12Z SOME LOW STRATUS IMPACTING NORTHERN TAF SITES INITIALLY SHOULD LIFT INTO A SCT-BKN VFR CU DECK BY LATE MORNING. NORTHERLY TO NORTHEASTERLY WINDS EXPECTED THROUGH THE PERIOD...MAY HAVE SOME GUSTS BY LATE MORNING INTO THE AFTERNOON HOURS. MAINLY VFR CONDITIONS EXPECTED BEYOND 15Z AT ALL TAF SITES. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...BEERENDS LONG TERM...DONAVON AVIATION...BEERENDS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1030 AM EDT FRI AUG 10 2012 .SYNOPSIS... A STRONG COLD FRONT WILL APPROACH OUR REGION FROM THE WEST TODAY AND TONIGHT...THEN CROSS CENTRAL NORTH CAROLINA SATURDAY AND SATURDAY NIGHT. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1030 AM FRIDAY... SKIES ARE OVERCAST WITH WIDESPREAD STRATUS THIS MORNING..BETWEEN AN UPPER DISTURBANCE AND ASSOCIATED PRECIP DEPARTING TO THE NORTHEAST...AND TWO MORE APPROACHING FROM BOTH THE NORTHWEST AND SOUTHWEST LATER TODAY. A FEW LIGHT SHOWERS ARE MOVING THROUGH THE PIEDMONT THIS MORNING...BUT OVERALL THERE IS A LULL ACROSS THE CAROLINAS BETWEEN THE AFOREMENTIONED UPPER FEATURES. AN UPPER LOW/SURFACE CYCLONE HAVE NOW DEVELOPED OVER THE GREAT LAKES AND THE ASSOCIATED COLD FRONT EXTENDS SOUTH THROUGH OH/KY/TN....WITH A STREAM OF 2 INCH PWS ACROSS THE NC/SC PIEDMONT AND COASTAL PLAIN. A LINE OF PREFRONTAL CONVECTION IS CURRENTLY MOVING THROUGH EASTERN TN AND WV...BUT THE DEEP LAYER FLOW IS FORECAST TO BECOME MORE SOUTHWESTERLY AS THE UPPER TROUGH CONTINUES TO DEEPEN... AND THE PROGRESSION OF CONVECTIVE LINE SHOULD SLOW AS IT CROSSES THE MOUNTAINS THIS MORNING. IN FACT... HRRR FORECASTS SHOW A LINE OF CONVECTION MOVING INTO THE WESTERN PIEDMONT CLOSER TO 00Z. MEANWHILE...THE AFOREMENTIONED DISTURBANCE NEAR THE GULF COAST SHOULD BE DRAWN NORTH-NORTHEASTWARD...APPROACHING THE SOUTHERN CWA BY 00Z. WHILE A FEW SHOWERS AND STORMS WILL BE POSSIBLE THROUGH MID AFTERNOON WITH WEAK DISTURBANCES IN THE MOIST SOUTHWESTERLY FLOW ALOFT...WE SHOULD BE ABLE TO PUSH MORE SIGNIFICANT POPS BACK UNTIL AFTER 21-22Z. CONCERNING THE SEVERE THREAT THROUGH THIS EVENING...IT APPEARS THE WIDESPREAD STRATUS MAY LINGER THROUGH MIDDAY...WITH MORNING PIREPS CONTINUING TO REPORT 3K FT DEPTH TO THE STRATUS. VISIBLE IMAGERY SHOWS MORE PROMINENT BREAKS IN THE CLOUDS OVER WESTERN NC AND OVER THE COASTAL PLAIN. THUS...TWO INSTABILITY AXES MAY DEVELOP IN THESE REGIONS...AND MODELS SUGGEST 1500 J/KG OR MORE OF MLCAPE POSSIBLE..WITH VALUES AROUND 1000 J/KG OVER THE PIEDMONT. STRONGER DEEP LAYER SHEAR WILL BE LOCATED WEST OF THE MOUNTAINS FOR MOST OF THE DAY...ALTHOUGH THE MID LEVEL HEIGHT GRADIENT WILL BEGIN TO STRENGTHEN THIS EVENING...AND THE RAP SHOWS 25-35KT OF 0-6KM BULK SHEAR DEVELOPING OVER THE WESTERN PIEDMONT. TO THE EAST...WHERE DEEP LAYER FLOW IS A BIT WEAKER...MORE LIKE 20-25KT OF DEEP BULK SHEAR...MORNING RAOBS SUGGEST A BELT OF 30KT 925-850MB FLOW EXISTS AND THE SPC MESOANALYSIS CURRENTLY SHOWS AN AXIS OF 20KT 0-1KM SHEAR OVER THE COASTAL PLAIN. SO WHILE DEEP SHEAR MAY NOT SUPPORT SUPERCELLULAR ACTIVITY... IT IS POSSIBLE THAT A FEW CLUSTERS OF STORMS OR EVEN DISCRETE CELLS WITH WEAK ROTATION COULD DEVELOP THIS EVENING. THIS IS ALL SIGNIFICANTLY DEPENDENT ON OUR DIURNAL DESTABILIZATION AND WHETHER OR NOT CONVECTION CAN HOLD TOGETHER SINCE THE MAIN FORCING MECHANISMS WILL NOT ARRIVE UNTIL CLOSER TO 00Z. OTHERWISE...HAVE MADE SOME MINOR ADJUSTMENTS TO AFTERNOON HIGHS...WITH SLIGHTLY HIGHER VALUES OVER THE EASTERN AND WESTERN AREAS...BUT GENERALLY 84-87 SHOULD STILL BE ATTAINABLE IF BREAKS IN CLOUDS DEVELOP BY MID AFTERNOON. -SMITH TONIGHT...SW FLOW WILL DEEPEN OVER CENTRAL NC IN RESPONSE TO AMPLIFYING TROUGH OVER THE EASTERN LAKES-OH VALLEY. THIS SUGGEST A THREAT FOR SHOWERS-STORMS TO TRAIN REPEATEDLY ACROSS THE SAME LOCATIONS. SINCE FLOW WILL BE TAPPING AN AIR MASS WITH A VERY HIGH MOISTURE CONTENT OVER THE NORTHERN GULF...COULD SEE A MODERATE FLASH FLOOD THREAT DEVELOP OVER CENTRAL NC OVERNIGHT. MODEL GUIDANCE DEPICT BEST LIFT ALOFT IN ASSOCIATION WITH THE UPPER JET WHILE LIFT BELOW 700MB WEAK AT BEST. THUS PLAN TO HAVE POPS NO HIGHER THAN 70-80 PERCENT OVER THE WEST HALF OVERNIGHT...TRENDING TO NEAR 60 PERCENT SE (WHICH MAY BE GENEROUS). TEMPS TODAY DEPENDENT ON THE AMOUNT OF SUN THAT OCCURS. EXPECT CONDITIONS TODAY SIMILAR TO THE PAST FEW DAYS WHERE MAX TEMPS IN THE MID 80S COMMON. MIN TEMPS TONIGHT UPPER 60S TO LOWER 70S. && .SHORT TERM /SATURDAY AND SATURDAY NIGHT/... AS OF 315 AM FRIDAY... SATURDAY...EXPECT SCATTERED CONVECTION TO BE ONGOING ACROSS CENTRAL NC SATURDAY MORNING. AS AIR MASS BECOMES MARGINALLY UNSTABLE IN THE AFTERNOON AND SURFACE COLD FRONT ENTERS THE MOUNTAINS...SHOULD SEE AN UPTICK IN CONVECTIVE COVERAGE IN THE AFTERNOON. BULK SHEAR VALUES 30-35KTS ACROSS THE ENTIRE FORECAST AREA SUGGEST DECENT POTENTIAL FOR ORGANIZED STORMS IN THE FORM OF BROKEN LINE SEGMENTS THOUGH INSTABILITY MAY BE LACKING FOR SEVERE STORMS DUE TO LIMITED INSOLATION CAUSED BY CONSIDERABLE CLOUDINESS AND SCATTERED SHOWERS. IF PARTIAL SUN OCCURS IN THE LATE MORNING INTO THE AFTERNOON...PROBABILITY FOR SEVERE STORMS WILL INCREASE EXPONENTIALLY. AGAIN...DUE TO TAP OF TROPICAL MOISTURE AND DEEP SW FLOW...COULD SEE SHOWERS-STORMS TRAIN NEWD ACROSS THE REGION...LEADING TO POSSIBLE FLASH FLOODING EPISODE. MAX TEMPS MAINLY IN THE MID 80S THOUGH IF SHOWERS MORE WIDESPREAD...COULD SEE MAX TEMPS 3-5 DEGREES COOLER...ESPECIALLY WEST HALF. WITH PASSAGE OF LOW-MID TROUGH SATURDAY EVENING IN THE WEST...EXPECT CHANCES FOR CONVECTION TO BEGIN TO DECREASE IN THIS REGION. MEANWHILE DECENT CHANCES FOR SCATTERED SHOWERS-STORMS SHOULD PERSIST THROUGH MIDNIGHT IN THE EAST. MIN TEMPS MID 60S NW TO NEAR 70-LOWER 70S SE. && .LONG TERM /SUNDAY THROUGH THURSDAY/... AS OF 245 AM FRIDAY... MID/UPPER LOW EXPECTED TO BE CENTERED INVOF THE NORTHERN GREAT LAKES REGION AND NEAR THE ONTARIO/QUEBEC BORDER 12Z SUNDAY IS EXPECTED TO CONTINUING LIFTING NNE ON SUNDAY. THIS WILL RESULT IN FLOW ALOFT ACROSS CENTRAL NC BECOMING MORE WESTERLY WITH DRIER AIR ALOFT CONTINUING TO FILTER INTO THE AREA. AT THE SURFACE THE WEAK FRONT IS EXPECTED TO WASHOUT/DISSIPATE ACROSS THE AREA ON SUNDAY INTO MONDAY. GIVEN THIS ALONG WITH THE DEPARTURE OF THE FORCING ALOFT AND MOIST AIR ALOFT... EXPECTED GENERALLY DRY CONDITIONS ON SUNDAY INTO MONDAY (OUTSIDE OF POSSIBLE A FEW LINGERING SHOWERS/STORMS ACROSS THE FAR EAST ON SUNDAY... SLIGHT CHANCE AT BEST THOUGH). CHANCE FOR POPS ARE EXPECTED TO INCREASE BY TUESDAY INTO TUESDAY NIGHT/PERHAPS LINGERING INTO WEDNESDAY/THURSDAY AS A LOW AMPLITUDE S/W TROUGH AND ASSOCIATED WEAK COLD FRONT/SURFACE TROUGH MOVE ACROSS THE AREA. GIVEN TIMING AND SOME STRENGTH DIFFERENCES WILL CONTINUE TO ONLY GO WITH A LOW END CHANCE POPS FOR TUESDAY/TUESDAY EVENING... WITH DIURNAL SLIGHT CHANCE POPS FOR WEDNESDAY INTO THURSDAY WITH THE REMNANT LINGERING SURFACE TROUGH. HIGH TEMPS DURING THE PERIOD ARE EXPECTED TO GENERALLY BE IN THE UPPER 80S TO LOWER 90S... WITH LOWS GENERALLY RANGING FROM THE UPPER 60S TO LOWER 70S (WITH MAYBE SOME LOW TEMPS IN THE LOWER TO MID 60S IN THE RURAL LOCATIONS AND NORTHWEST PIEDMONT ON MONDAY MORNING). && .AVIATION /12Z FRIDAY THROUGH TUESDAY/... AS OF 707 AM FRIDAY... LOW CLOUDS HAVE DEVELOP OVER MOST OF CENTRAL NC EARLY THIS MORNING IN WAKE OF THE SHOWERS AND SCATTERED T-STORMS THAT CROSSED THE WESTERN COUNTIES OVERNIGHT. CEILINGS IN THE IFR/LOW END MVFR RANGE. CEILINGS SHOULD GRADUALLY LIFT TOT HE HIGH END MVFR/LOW END VFR BY LATE MORNING. ANY FOG ACROSS THE REGION SHOULD BE SPOTTY AND DIMINISH BY MID MORNING (IF NOT SOONER). WHILE ISOLATED SHOWERS POSSIBLE THROUGH EARLY AFTERNOON...EXPECT CONVECTION TO GROW IN COVERAGE AND INTENSITY BY MID AFTERNOON...PARTICULARLY IN THE VICINITY OF KFAY AND KRWI WHERE INITIAL MID LEVEL TROUGH WILL RESIDE. IN THE NW PIEDMONT INCLUDING THE TRIAD TERMINALS...BETTER CONVECTIVE PROBABILITIES MAY HOLD OFF UNTIL EVENING AS A MID LEVEL TROUGH APPROACHES FROM THE NW. THIS FEATURE MAY SUSTAIN SCATTERED CONVECTION IN VICINITY OF KINT AND KGSO WELL INTO THE NIGHT. EXPECT EPISODES OF SCATTERED SHOWERS AND T-STORMS ACROSS CENTRAL NC SATURDAY INTO SATURDAY EVENING WITH ASSOCIATED MVFR CONDITIONS. AT THIS TIME...IT APPEARS THE HEAVIER SHOWERS AND STORMS WILL OCCUR SATURDAY AFTERNOON ALONG AND EAST OF HIGHWAY 1. DRIER MORE STABLE AIR WILL GRADUALLY OVERSPREAD CENTRAL NC LATE SATURDAY NIGHT INTO SUNDAY LEADING TO IMPROVING AVIATION CONDITIONS. MAINLY VFR CONDITIONS EXPECTED MONDAY INTO TUESDAY. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...WSS NEAR TERM...WSS SHORT TERM...WSS LONG TERM...BSD AVIATION...WSS
AREA FORECAST DISCUSSION
NWS BISMARCK ND
927 AM CDT FRI AUG 10 2012 .DISCUSSION...LATEST VISIBLE SATELLITE IMAGERY ALONG WITH REGIONAL RADAR SHOWS A COUPLE SHORTWAVES APPROACHING/PROPAGATING THROUGH WESTERN NORTH DAKOTA. THE FIRST WAS SEEN NEAR WATFORD CITY WITH AN ISOLATED SHOWER IN FAR EASTERN DUNN COUNTY...WHICH HAS WEAKENED AND DISSIPATED. A MORE SUBSTANTIAL AREA OF SHOWERS AND ISOLATED THUNDERSTORMS WAS NOTED FROM GLASGOW SOUTH TO BILLINGS ASSOCIATED WITH A SECOND SHORTWAVE. LATEST RADAR TRENDS SHOW SOME WEAKENING AND THE LATEST HRRR MODEL HAS THIS AREA REACHING THE WESTERN BORDER BY AROUND 18Z AND THEN INTO OUR SOUTHWEST ZONES THIS AFTERNOON...BUT IN A MUCH WEAKER STATE THAN CURRENT. THIS WILL BRING QUITE A BIT OF CLOUDINESS TO THE WEST LATER THIS MORNING AND HAVE INCREASED CLOUD COVERAGE TO ACCOUNT FOR THIS. MAY HAVE TO LOWER HIGH TEMPERATURES IN WEST IF CLOUDS REMAIN MOST OF THE AFTERNOON. REST OF FORECAST REMAINS ON TRACK WITH SATURDAY BECOMING INCREASING WET ACROSS WESTERN AND CENTRAL NORTH DAKOTA WITH UPWARDS OF NEAR/AROUND AN INCH POSSIBLE IN MANY LOCALES. && .AVIATION...SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS IN EASTERN MONTANA CONTINUE TO MOVE TOWARD THE WESTERN NORTH DAKOTA BORDER. INDICATIONS ARE THIS AREA WILL WEAKEN INTO A SCATTERED SHOWER REGIME THROUGH THE MORNING...HOWEVER WILL MONITOR THE TRENDS AND MAY HAVE TO ADD A VCSH/VCTS IN KISN AND/OR KDIK IF THE AREA HOLDS TOGETHER. OTHERWISE SHOWERS AND STORMS ARE EXPECTED TO INCREASE IN COVERAGE AFTER 00Z TONIGHT...WITH MAIN IMPACTS AT KISN/KDIK THROUGH 12Z SATURDAY. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION...KS AVIATION...RK
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
1201 PM EDT FRI AUG 10 2012 .SYNOPSIS... A STRONG UPPER LEVEL TROUGH WILL CROSS OVER THE GREAT LAKES TODAY...AND PUSH A COLD FRONT ACROSS THE MID ATLANTIC. THIS FRONT WILL TRIGGER NUMEROUS SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND EVENING...WITH A FEW STORMS POSSIBLY BECOMING STRONG TO SEVERE. ONCE THE COLD FRONT DEPARTS LATER TONIGHT INTO SATURDAY...HIGH PRESSURE WILL ARRIVE TO PROVIDE COOLER AND DRIER CONDITIONS FOR THE REST OF THIS WEEKEND INTO EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1200 PM EDT FRIDAY... THE SHOWERS OVER WEST VIRGINIA ARE STILL PRESENT BUT GRADUALLY DECAYING. NEW DEVELOPMENT OF SHOWERS AND THUNDERSTORMS HAS BEEN DELAYED A FEW HOURS TOWARD THE MID AFTERNOON AND EVENING...AS INSTABILITY IS CURRENTLY STILL LACKING. THE THREAT FOR SEVERE WEATHER TODAY CONTINUES TO DIMINISH DUE TO CLOUD COVER REMAINING QUITE THICK OVER THE AREA...BUT SOME SUNSHINE IS PEEKING THROUGH ALONG THE BLUE RIDGE. MINOR TWEAKS WERE MADE TO THE POPS AND TEMPERATURES TO ACCOUNT FOR THE RECENT TRENDS ON RADAR AND SATELLITE. ALSO...WINDS WERE BUMPED UPWARD DUE TO ROANOKE AND DANVILLE BOTH OBSERVING A GUSTY SOUTHWEST WIND DEVELOPING...WHICH SHOULD CONTINUE THROUGH THE AFTERNOON. AS OF 1015 AM EDT FRIDAY... DUE TO THE DEPARTING BAND OF SHOWERS AND THUNDERSTORMS FROM LAST NIGHT...AND ANOTHER SMALL BAND OF SHOWERS CROSSING OVER SOUTHEAST WEST VIRGINIA AT THIS MOMENT...THERE WILL BE LOTS OF CLOUD COVER TO ERODE OVER THE AREA FOR ANY SIGNIFICANT RISK OF SEVERE WEATHER. THE SMALL BAND OF SHOWERS OVER WEST VIRGINIA WILL GRADUALLY DISSIPATE AS IT CROSSES THE BLUE RIDGE IN A FEW HOURS. RECOVERING THE INSTABILITY WILL BE THE KEY FOR TODAY. LAPSE RATES IN THE 12Z RNK SOUNDING ARE NOT IMPRESSIVE...BUT WITH ENOUGH DAYTIME HEATING AND DYNAMICAL SUPPORT AS THE SURFACE COLD FRONT DRAWS CLOSER...THERE SHOULD BE SUFFICIENT SUPPORT FOR THE GROWTH OF NUMEROUS SHOWERS AND THUNDERSTORMS LATER THIS AFTERNOON. IF ANY OF THESE STORMS BECOME STRONG TO SEVERE...DAMAGING WINDS AND HEAVY RAIN WILL BE THE PRIMARY THREATS. SINCE CLOUD COVER AND BANDS OF CONVECTION WILL BE ONGOING THROUGHOUT THE DAY...THE TEMPERATURE FORECAST IS QUITE PROBLEMATIC. AT THIS TIME...TEMPERATURES WERE BUMPED UPWARD FOR HIGHS WEST OF THE BLUE RIDGE DUE TO SOME BREAKS IN THE CLOUDS. OTHER AREAS WERE KEPT CLOSE TO THE PREVIOUS FORECAST AND MOS GUIDANCE...WITH HIGHS IN THE MID TO UPPER 70S WEST OF THE BLUE RIDGE...AND LOWER TO MID 80S IN THE PIEDMONT. WITH REGARDS TO POPS...A SMALL AREA OF LIKELY CHANCES WERE UTILIZED TO ACCOUNT FOR THE DECAYING BAND OF SHOWERS OVER WEST VIRGINIA THIS MORNING. LIKELY POPS WEST OF THE BLUE RIDGE...AND CATEGORICAL POPS OVER THE PIEDMONT WERE PLACED THIS AFTERNOON AND EVENING...AS THERE SHOULD BE BANDED CONVECTION FORMING ALONG AND WEST OF THE BLUE RIDGE...AND BECOMING MORE ORGANIZED AS IT HEADS EASTWARD. AS OF 315 AM EDT FRIDAY... MAIN CONCERN TODAY WITH THE DEGREE OF POSSIBLE RENEWED CONVECTION LATER ON AS THE UPPER LOW TO THE NW PROPELS A STRONG COLD FRONT TO ALONG THE WESTERN SLOPES THIS EVENING AND EAST OF THE BLUE RIDGE OVERNIGHT. AGAIN ONE OF THE MAIN FACTORS IS WITH JUST HOW MUCH DEEP INSTABILITY CAN BE GENERATED THIS AFTERNOON IN THE WAKE OF THE CURRENT MVC THAT WILL EXIT THE CWA BY DAYBREAK. THIS FEATURE AND ITS CONVECTION HAVE BASICALLY REMOVED ANY LINGERING CAPE FROM THU EVENING AND WILL NEED A PERIOD OF STRONG HEATING TO REGENERATE ENOUGH INSTABILITY FOR A MORE WIDESPREAD SEVERE THREAT. LATEST FCST SOUNDINGS DO SHOW WIND FIELDS STRENGTHENING/BACKING ALOFT AHEAD OF THE UPSTREAM TROF THRU THIS EVENING SUGGESTING POTENTIAL FOR BANDS OF DEEPER CONVECTION THAT MAY EVENTUALLY LINE UP ESPCLY OUT EAST BY THIS EVENING. HOWEVER LATEST MODELS REMAIN SPREAD ACROSS THE BOARD WITH TIMING AND LOCATION ISSUES OF PRE- FRONTAL LIFT PER SLOWNESS IN INITIALIZING WITH THE CURRENT REMNANT MCS ATTM. APPEARS BEST SOLUTION IS TO LEAN TOWARD THE LATEST HRRR AND GO WITH DEVELOPMENT OF MULTICELLULAR BANDS OVER THE MOUNTAINS BY EARLY AFTERNOON PER UNIDIRECTIONAL FLOW AND THETA-E RIDGING...WITH THIS COVERAGE OR ANOTHER LINE GRADUALLY ORGANIZING UPON HEADING EAST INTO BETTER INSTABILITY OUT EAST THRU EARLY EVENING. THIS AGAIN BASED ON AT LEAST SOME HEATING AS SUGGESTED BY THE LATEST NAM WHICH BREAKS OPEN THE MID DECK LATER THIS MORNING AHEAD OF THE BOUNDARY. THUS HAVE ADJUSTED POPS TO REFLECT A BREAK IN COVERAGE PER WEAK SUBSIDENCE IN BEHIND THE PASSING VORT EARLY THIS MORNING...INCREASING TO LIKELY/CAT POPS WEST EARLY/MID AFTERNOON...THEN TRANSLATING EAST INTO EARLY THIS EVENING. THINK COVERAGE MOVING ENOUGH TO PRECLUDE A FLASH FLOOD WATCH BUT CERTAINLY A WIND THREAT GIVEN DECENT FCST DCAPES WHICH WILL COVER IN THE HWO PER SWODY1 SLIGHT RISK. WILL STAY ON THE WARM SIDE OF MOS TEMPS TODAY AS THINKING SOME INSOLATION BUT IF CLOUDS HOLD AND CONVECTION FASTER THEN HIGH BUST POTENTIAL REMAINS. EXPECT MAIN AXIS OF CONVECTION TO BE EAST OF THE MOUNTAINS THIS EVENING AND MAY TAKE SOME TIME TO EXIT THE PIEDMONT AS ANOTHER WEAK IMPULSE RIDES UP THE FRONT. THINK SEVERE POTENTIAL LIMITED BEHIND THE INIT WAVE OF STORMS BUT LINGERING HEAVY RAIN THREAT COULD PERSIST WHILE SHOWERS BECOME WIDELY SCATTERED OR END BEHIND THE BOUNDARY OVER THE MOUNTAINS OVERNIGHT. THEREFORE DID DECREASE POPS A BIT FASTER WEST THINKING CONVECTION WILL HELP TAKE DEEP MOISTURE TO THE EAST LATE...BUT LIKELY STILL LOTS OF CLOUDS AS THE UPPER FLOW REMAINS SW AND PARALLEL TO THE SFC FRONT. MAIN PUSH OF 85H COOL ADVECTION WILL STILL BE WEST OF THE BLUE RIDGE LATE TONIGHT SO KEEPING TEMPS WARMER OUT EAST AND NOT QUITE AS COOL MOUNTAINS PER CLOUD COVER. OTRW RANGE OF LOWS FROM AROUND 60 FAR WEST TO 65-70 SE LOOKS BEST. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 300 AM EDT FRIDAY... SHORTWAVE PIVOTS ACROSS THE CENTRAL APPALACHIANS SATURDAY AFTERNOON. THIS WILL KEEP THE THREAT OF SHOWERS AND ISOLATED THUNDERSTORMS GOING IN THE EAST WITH COOL POOL ALOFT. 8H TEMPS COOL TO +14C...SO WITH SOME CLOUD COVER FROM THE COLDER AIR ALOFT...EXPECT HIGHS CLOSE TO THE ADJMETBC WITH READINGS FROM THE MID 70S IN THE MOUNTAINS TO THE MID 80S IN THE SOUTHEAST. DRIER AIR WILL FINALLY WORKS IN FROM THE NORTHWEST SATURDAY NIGHT INTO SUNDAY WITH DEWPOINTS DROPPING INTO THE UPPER 40S/LOWER 50S IN THE HIGHER ELEVATIONS WITH MID 50S VALLEYS. THE PIEDMONT COULD SEE SOME 50S DEWPOINTS BUT HARD TO DISPLACE THE HUMID AIRMASS ACROSS THE CAROLINAS AS THE FLOW ALOFT STAYS WSW. PLAYED LOW TEMPERATURES SATURDAY NIGHT FROM THE LOWER 50S IN THE MOUNTAINS TO THE LOWER 60S IN THE EAST. ON SUNDAY...TEMPERATURES MODERATE WITH WSW FLOW AND MORE SUNSHINE. HEIGHTS/8H TEMPERATURES INCREASE AGAIN...HIGHS SUNDAY RETURNING TO AROUND 80 DEGREES IN THE MOUNTAINS TO THE UPPER 80S IN THE SOUTHEAST. LEANED TOWARDS THE ECMWFBC FOR SUNDAY NIGHT LOW TEMPERATURES WITH VALUES FROM THE MID 50S IN THE WEST TO THE MID 60S IN THE EAST. && .LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 400 PM EDT THURSDAY... DRIER AIRMASS WILL BE DISPLACED DURING THIS PERIOD AS THE FRONT FROM THE SHORT TERM PERIOD STALLS ACROSS THE CAROLINAS/TN VALLEY THEN SHIFTS SLOWLY NORTH BY TUESDAY AS ANOTHER WAVE OF LOW PRESSURE SHIFTS ACROSS IT FROM THE LOWER MISSOURI VALLEY INTO THE VA TIDEWATER FROM MON-TUE. THIS FRONT WILL BE CLOSE ENOUGH THAT SHOWER/TSRA CHANCES INCREASE AGAIN BY TUESDAY. ONCE THE SHORTWAVE/ASSOCIATED SFC LOW PASS TUESDAY AFTERNOON...WEAK HIGH PRESSURE WILL PUSH THE FRONT BACK SOUTH INTO THE GA/SC BY WEDNESDAY AND THE AIRMASS DRIES OUT SOME...BUT THE UPPER TROUGH IS NOT AS DEEP AS THIS WEEKENDS. OVERALL...THE TEMPS NEXT WEEK WILL AVERAGE 80S/LOWER 90S FOR HIGHS AND 60S FOR LOWS. && .AVIATION /16Z FRIDAY THROUGH TUESDAY/... AS OF 650 AM EDT FRIDAY... INITIAL AREA OF LEFTOVER SHOWERS FROM EARLIER MCS SLOWLY FADING ACROSS THE EAST AND SHOULD ONLY AFFECT KLYH DURING THE NEXT HOUR OR TWO. OTRW LOOKING AT MAINLY MVFR CIGS THRU MID MORNING WITH PERIODS OF IFR INCLUDING PATCHY FOG ESPCLY VALLEYS AND AROUND KDAN/KLYH. NEXT BAND OF DEVELOPING CONVECTION NOW WEST OF THE MOUNTAINS LOOKS TO ARRIVE ACROSS SE WVA AROUND MID MORNING BEFORE WEAKENING. THUS WILL INCLUDE A VCSH AT KBLF/KLWB AND SHOW CIGS LIFTING INTO VFR LEVELS ELSW BY LATE MORNING OR MIDDAY AS SW FLOW STARTS TO MIX THINGS OUT. JUST HOW FAR EAST THIS BROKEN BAND OF SHRA/TSRA MAKES IT IFFY GIVEN RATHER STABLE CONDITIONS SO WILL HOLD OFF PUSHING COVERAGE EASTWARD FOR NOW. HOWEVER EXPECT TO SEE MORE SHOWERS AND THUNDERSTORMS TAKE SHAPE AHEAD OF THE UPSTREAM COLD FRONT LATE THIS MORNING INTO THE AFTERNOON AS A DEEP UPPER LEVEL TROUGH APPROACHES THE AREA. WILL BE LOOKING AT A FEW STRONG STORMS TO START THE AFTERNOON...AND EXPECT THAT THESE STORMS WILL FORM INTO A LINE OR TWO JUST AHEAD OF THE COLD FRONT AS IT ENTERS THE PIEDMONT REGION DURING EARLY EVENING. THESE STORMS WILL BE CAPABLE OF PRODUCING STRONG WINDS ALONG WITH PERIODIC MVFR/IFR THIS AFTERNOON. THEREFORE GIVEN EXPECTED COVERAGE WILL INCLUDE CONVECTIVE MENTION AS PREVAILING FROM WEST TO EAST STARTING THIS AFTERNOON. THUNDERSTORM ACTIVITY IS EXPECTED TO END ACROSS THE AREA AS THE FRONT EXITS TO THE EAST DURING LATE EVENING...AT WHICH POINT DRIER AIR ASSOCIATED WITH HIGH PRESSURE WILL RESULT IN VFR CONDITIONS HEADING INTO THE EARLY PART OF NEXT WEEK. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...PW NEAR TERM...JH/PW SHORT TERM...KK LONG TERM...WP AVIATION...JH/KM/NF
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
703 AM EDT FRI AUG 10 2012 .SYNOPSIS... A STRONG UPPER LEVEL TROUGH WILL PASS INTO THE GREAT LAKES TODAY...DRAGGING A COLD FRONT ACROSS THE REGION THIS EVENING. THIS WILL RESULT IN ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND EVENING...WITH A FEW STORMS BECOMING STRONG TO SEVERE. ONCE THE COLD FRONT MOVES EAST OF THE AREA LATE TONIGHT...HIGH PRESSURE WILL BUILD IN...BRINGING COOLER AND DRIER AIR IN FOR THE REMAINDER OF THE WEEKEND AND THE EARLY PART OF NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 315 AM EDT FRIDAY... MAIN CONCERN TODAY WITH THE DEGREE OF POSSIBLE RENEWED CONVECTION LATER ON AS THE UPPER LOW TO THE NW PROPELS A STRONG COLD FRONT TO ALONG THE WESTERN SLOPES THIS EVENING AND EAST OF THE BLUE RIDGE OVERNIGHT. AGAIN ONE OF THE MAIN FACTORS IS WITH JUST HOW MUCH DEEP INSTABILITY CAN BE GENERATED THIS AFTERNOON IN THE WAKE OF THE CURRENT MVC THAT WILL EXIT THE CWA BY DAYBREAK. THIS FEATURE AND ITS CONVECTION HAVE BASICALLY REMOVED ANY LINGERING CAPE FROM THU EVENING AND WILL NEED A PERIOD OF STRONG HEATING TO REGENERATE ENOUGH INSTABILITY FOR A MORE WIDESPREAD SEVERE THREAT. LATEST FCST SOUNDINGS DO SHOW WIND FIELDS STRENGTHENING/BACKING ALOFT AHEAD OF THE UPSTREAM TROF THRU THIS EVENING SUGGESTING POTENTIAL FOR BANDS OF DEEPER CONVECTION THAT MAY EVENTUALLY LINE UP ESPCLY OUT EAST BY THIS EVENING. HOWEVER LATEST MODELS REMAIN SPREAD ACROSS THE BOARD WITH TIMING AND LOCATION ISSUES OF PRE- FRONTAL LIFT PER SLOWNESS IN INITIALIZING WITH THE CURRENT REMNANT MCS ATTM. APPEARS BEST SOLUTION IS TO LEAN TOWARD THE LATEST HRRR AND GO WITH DEVELOPMENT OF MULTICELLULAR BANDS OVER THE MOUNTAINS BY EARLY AFTERNOON PER UNIDIRECTIONAL FLOW AND THETA-E RIDGING...WITH THIS COVERAGE OR ANOTHER LINE GRADUALLY ORGANIZING UPON HEADING EAST INTO BETTER INSTABILITY OUT EAST THRU EARLY EVENING. THIS AGAIN BASED ON AT LEAST SOME HEATING AS SUGGESTED BY THE LATEST NAM WHICH BREAKS OPEN THE MID DECK LATER THIS MORNING AHEAD OF THE BOUNDARY. THUS HAVE ADJUSTED POPS TO REFLECT A BREAK IN COVERAGE PER WEAK SUBSIDENCE IN BEHIND THE PASSING VORT EARLY THIS MORNING...INCREASING TO LIKELY/CAT POPS WEST EARLY/MID AFTERNOON...THEN TRANSLATING EAST INTO EARLY THIS EVENING. THINK COVERAGE MOVING ENOUGH TO PRECLUDE A FLASH FLOOD WATCH BUT CERTAINLY A WIND THREAT GIVEN DECENT FCST DCAPES WHICH WILL COVER IN THE HWO PER SWODY1 SLIGHT RISK. WILL STAY ON THE WARM SIDE OF MOS TEMPS TODAY AS THINKING SOME INSOLATION BUT IF CLOUDS HOLD AND CONVECTION FASTER THEN HIGH BUST POTENTIAL REMAINS. EXPECT MAIN AXIS OF CONVECTION TO BE EAST OF THE MOUNTAINS THIS EVENING AND MAY TAKE SOME TIME TO EXIT THE PIEDMONT AS ANOTHER WEAK IMPULSE RIDES UP THE FRONT. THINK SEVERE POTENTIAL LIMITED BEHIND THE INIT WAVE OF STORMS BUT LINGERING HEAVY RAIN THREAT COULD PERSIST WHILE SHOWERS BECOME WIDELY SCATTERED OR END BEHIND THE BOUNDARY OVER THE MOUNTAINS OVERNIGHT. THEREFORE DID DECREASE POPS A BIT FASTER WEST THINKING CONVECTION WILL HELP TAKE DEEP MOISTURE TO THE EAST LATE...BUT LIKELY STILL LOTS OF CLOUDS AS THE UPPER FLOW REMAINS SW AND PARALLEL TO THE SFC FRONT. MAIN PUSH OF 85H COOL ADVECTION WILL STILL BE WEST OF THE BLUE RIDGE LATE TONIGHT SO KEEPING TEMPS WARMER OUT EAST AND NOT QUITE AS COOL MOUNTAINS PER CLOUD COVER. OTRW RANGE OF LOWS FROM AROUND 60 FAR WEST TO 65-70 SE LOOKS BEST. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 300 AM EDT FRIDAY... SHORTWAVE PIVOTS ACROSS THE CENTRAL APPALACHIANS SATURDAY AFTERNOON. THIS WILL KEEP THE THREAT OF SHOWERS AND ISOLATED THUNDERSTORMS GOING IN THE EAST WITH COOL POOL ALOFT. 8H TEMPS COOL TO +14C...SO WITH SOME CLOUD COVER FROM THE COLDER AIR ALOFT...EXPECT HIGHS CLOSE TO THE ADJMETBC WITH READINGS FROM THE MID 70S IN THE MOUNTAINS TO THE MID 80S IN THE SOUTHEAST. DRIER AIR WILL FINALLY WORKS IN FROM THE NORTHWEST SATURDAY NIGHT INTO SUNDAY WITH DEWPOINTS DROPPING INTO THE UPPER 40S/LOWER 50S IN THE HIGHER ELEVATIONS WITH MID 50S VALLEYS. THE PIEDMONT COULD SEE SOME 50S DEWPOINTS BUT HARD TO DISPLACE THE HUMID AIRMASS ACROSS THE CAROLINAS AS THE FLOW ALOFT STAYS WSW. PLAYED LOW TEMPERATURES SATURDAY NIGHT FROM THE LOWER 50S IN THE MOUNTAINS TO THE LOWER 60S IN THE EAST. ON SUNDAY...TEMPERATURES MODERATE WITH WSW FLOW AND MORE SUNSHINE. HEIGHTS/8H TEMPERATURES INCREASE AGAIN...HIGHS SUNDAY RETURNING TO AROUND 80 DEGREES IN THE MOUNTAINS TO THE UPPER 80S IN THE SOUTHEAST. LEANED TOWARDS THE ECMWFBC FOR SUNDAY NIGHT LOW TEMPERATURES WITH VALUES FROM THE MID 50S IN THE WEST TO THE MID 60S IN THE EAST. && .LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 400 PM EDT THURSDAY... DRIER AIRMASS WILL BE DISPLACED DURING THIS PERIOD AS THE FRONT FROM THE SHORT TERM PERIOD STALLS ACROSS THE CAROLINAS/TN VALLEY THEN SHIFTS SLOWLY NORTH BY TUESDAY AS ANOTHER WAVE OF LOW PRESSURE SHIFTS ACROSS IT FROM THE LOWER MISSOURI VALLEY INTO THE VA TIDEWATER FROM MON-TUE. THIS FRONT WILL BE CLOSE ENOUGH THAT SHOWER/TSRA CHANCES INCREASE AGAIN BY TUESDAY. ONCE THE SHORTWAVE/ASSOCIATED SFC LOW PASS TUESDAY AFTERNOON...WEAK HIGH PRESSURE WILL PUSH THE FRONT BACK SOUTH INTO THE GA/SC BY WEDNESDAY AND THE AIRMASS DRIES OUT SOME...BUT THE UPPER TROUGH IS NOT AS DEEP AS THIS WEEKENDS. OVERALL...THE TEMPS NEXT WEEK WILL AVERAGE 80S/LOWER 90S FOR HIGHS AND 60S FOR LOWS. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/... AS OF 650 AM EDT FRIDAY... INITIAL AREA OF LEFTOVER SHOWERS FROM EARLIER MCS SLOWLY FADING ACROSS THE EAST AND SHOULD ONLY AFFECT KLYH DURING THE NEXT HOUR OR TWO. OTRW LOOKING AT MAINLY MVFR CIGS THRU MID MORNING WITH PERIODS OF IFR INCLUDING PATCHY FOG ESPCLY VALLEYS AND AROUND KDAN/KLYH. NEXT BAND OF DEVELOPING CONVECTION NOW WEST OF THE MOUNTAINS LOOKS TO ARRIVE ACROSS SE WVA AROUND MID MORNING BEFORE WEAKENING. THUS WILL INCLUDE A VCSH AT KBLF/KLWB AND SHOW CIGS LIFTING INTO VFR LEVELS ELSW BY LATE MORNING OR MIDDAY AS SW FLOW STARTS TO MIX THINGS OUT. JUST HOW FAR EAST THIS BROKEN BAND OF SHRA/TSRA MAKES IT IFFY GIVEN RATHER STABLE CONDITIONS SO WILL HOLD OFF PUSHING COVERAGE EASTWARD FOR NOW. HOWEVER EXPECT TO SEE MORE SHOWERS AND THUNDERSTORMS TAKE SHAPE AHEAD OF THE UPSTREAM COLD FRONT LATE THIS MORNING INTO THE AFTERNOON AS A DEEP UPPER LEVEL TROUGH APPROACHES THE AREA. WILL BE LOOKING AT A FEW STRONG STORMS TO START THE AFTERNOON...AND EXPECT THAT THESE STORMS WILL FORM INTO A LINE OR TWO JUST AHEAD OF THE COLD FRONT AS IT ENTERS THE PIEDMONT REGION DURING EARLY EVENING. THESE STORMS WILL BE CAPABLE OF PRODUCING STRONG WINDS ALONG WITH PERIODIC MVFR/IFR THIS AFTERNOON. THEREFORE GIVEN EXPECTED COVERAGE WILL INCLUDE CONVECTIVE MENTION AS PREVAILING FROM WEST TO EAST STARTING THIS AFTERNOON. THUNDERSTORM ACTIVITY IS EXPECTED TO END ACROSS THE AREA AS THE FRONT EXITS TO THE EAST DURING LATE EVENING...AT WHICH POINT DRIER AIR ASSOCIATED WITH HIGH PRESSURE WILL RESULT IN VFR CONDITIONS HEADING INTO THE EARLY PART OF NEXT WEEK. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...JH/NF NEAR TERM...JH SHORT TERM...KK LONG TERM...WP AVIATION...JH/KM/NF
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1028 AM MDT FRI AUG 10 2012 .SHORT TERM...(TODAY THROUGH SATURDAY) ISSUED AT 300 AM MDT FRI AUG 10 2012 MODELS CONTINUE TO SHOW EMBEDDED WAVES IN THE MOIST FLOW WHICH COMBINING WITH AFTERNOON HEATING WILL BE THE FORCING MECHANISMS FOR CONVECTION TODAY. RUC13 SHOWS THE BEST DYNAMICS MOVING ACROSS THE EASTERN UTAH THIS MORNING INTO WEST-CENTRAL COLORADO BY THIS AFTERNOON. EXPECT ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS TO DEVELOP ACROSS THE ENTIRE FORECAST AREA...WITH THE BEST CHANCE OF LOCALLY HEAVY RAIN ACROSS SOUTHERN AND EXTENDING NORTH ACROSS CENTRAL SECTIONS TODAY. GUSTY OUTFLOW WINDS TO 50 MPH ARE ALSO POSSIBLE NEAR STORMS ESPECIALLY ACROSS CENTRAL AND NORTHERN SECTIONS. MORE ENERGETIC TROF MOVING INTO THE PACIFIC NORTHWEST LATE THIS EVENING WILL BE PUSHING ACROSS THE NORTHERN ROCKIES BY THIS TIME TOMORROW NIGHT. AS IT DOES SO THE UPPER HIGH WILL BE SUPPRESSED SOUTH OF THE 4 CORNERS REGION AND BRINGING IN SOME STRONGER WESTERLY FLOW AS THE GRADIENT TIGHTENS. THE GOES DERIVED SATELLITE IMAGERY THIS MORNING IS SHOWING GOOD MOISTURE OVER SOUTHERN CALIFORNIA/SOUTHERN NEVADA AND THE 320K MOISTURE TRANSPORT VECTS SHOW THIS MOISTURE BEING PULLED INTO OUR CWA AS IT GETS CAUGHT UP IN THE FASTER WESTERLIES. THERE IS NO DISTINCT OR STRONG FORCING FOR ASCENT EVIDENT IN THE SHORT TERM MODELS OVERNIGHT. HOWEVER BOTH GFS/NAM SHOW PWATS SURGING THROUGH THE EARLY MORNING HOURS AND POT VORT MOVING ALONG THE NORTHERN BORDER AS UPPER JET MAX APPROACHES SO THINK THERE WILL BE SOME LINGERING CONVECTION TO DEAL WITH AND BOOSTED POPS SLIGHTLY AND FAVORED ACROSS THE NORTHERN 1/3 OF THE CWA. WITH MOISTURE IN PLACE SATURDAY ADDED DYNAMICS FROM AN UPPER LEVEL SPEED MAX MOVING OVER NORTHERN COLORADO SHOULD LEAD TO ANOTHER ACTIVE DAY...THOUGH MODELS ARE A LITTLE DIFFERENT ON TIMING AND COVERAGE. NAM SOLN PVU FIELDS SHOW THE SHORT WAVE ENERGY DIPPING INTO NORTHERN COLORADO EARLY IN THE DAY AS IT HAS A STRONGER SYSTEM OVER THE NORTHERN ROCKIES...GFS NOT DEEPENING THE SYSTEM QUITE AS MUCH AND KEEPS ANY SHORT WAVE FORCING JUST NORTH OF OUR BORDER. BY AFTERNOON HOWEVER BOTH MODELS HAVE UPPER LEVEL DIVERGENCE OVER OUR CENTRAL CWA AND WEAK SUBSIDENCE FILTERING INTO THE NORTH. THE INHERITED POPS FOR SATURDAY COVERED THIS WELL AND MADE JUST A FEW TWEAKS UPWARD WITH SLIGHT HIGHER CONFIDENCE. STILL CHANCE OF HEAVY RAINFALL BUT STORM MOTIONS WILL BE ON THE INCREASE WHICH MAY ENHANCE THE OUTFLOW WIND THREAT. TEMPERATURES SHOWING DIVERGING TREND IN GUIDANCE WITH NAM LOWERING DUE TO BEING MORE ACTIVE. USED A BLEND BUT GAVE MORE WEIGHT TO THE WARMER GUIDANCE ATTM. .LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY) ISSUED AT 300 AM MDT FRI AUG 10 2012 AS THE FLOW BECOME MORE NORTHWESTERLY IN THE WAKE OF THE NORTHERN SYSTEM DRIER AIR LOOKS TO FILTER INTO THE CWA SATURDAY NIGHT WITH PWATS KNOCKING BACK TO UNDER .75 OVER ALL BUT THE FAR SOUTHWESTERN PORTION OF THE CWA. THIS SHOULD ALLOW CONVECTION TO TAPER OFF OVERNIGHT AND LEAD TO COOLER LOW TEMPERATURES. THIS DRY AIR WILL BE IN PLACE FOR ONLY A SHORT TIME AS PWATS LOOK TO REBOUND BY LATE SUNDAY AS THE UPPER HIGH CENTERS OVER THE SOUTHERN HIGH PLAINS. WITH A LATE MOISTURE PUSH SOME STORMS MAY MAKE IT INTO THE VALLEYS BUT FOR THE MOST PART THINK MOST STORM WILL BE MORE ROOTED TO THE TERRAIN. NOT MUCH CHANGE IN THE WEATHER PATTERN INTO THE EXTENDED PERIOD...WITH SOUTHERLY MOIST FLOW CONTINUING INTO THE EARLY WORK WEEK WITH A CHANCE OF AFTERNOON AND EVENING THUNDERSTORMS EXPECTED EACH DAY THROUGH WEDNESDAY. MODELS ARE HINTING AT THE RIDGE BUILDING TO OUR WEST BY THURSDAY WHICH WOULD GENERATE SLIGHTLY DRIER CONDITIONS BY LATE IN THE WEEK WITH A DECREASING THREAT OF SHOWERS AND THUNDERSTORMS. EXPECT SEASONABLY WARM TEMPERATURES THROUGH THE EXTENDED PERIOD. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 1028 AM MDT FRI AUG 10 2012 EXPECT OCCASIONAL MVFR CONDITIONS AT KEGE AND KASE THIS AFTERNOON AND EVENING AS SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS DEVELOP OVER AND NEAR THE MOUNTAINS. LOCAL HEAVY RAIN IS POSSIBLE ALONG WITH WIND GUSTS TO 45 MPH. THUNDERSTORMS WILL AFFECT THE VALLEYS AFTER 20Z. THE GREATEST AREAL COVERAGE OF SHOWERS AND THUNDERSTORMS WILL BE OVER SOUTHWEST CO AND SOUTHEAST UT. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...NONE. UT...NONE. && $$ SHORT TERM...15/MPM LONG TERM...MPM AVIATION...CC
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1221 PM CDT FRI AUG 10 2012 ...UPDATED AVIATION DISCUSSION... .SHORT TERM /TODAY/... MAIN FOCUS TODAY WILL BE ON CLOUD COVER AND TEMPERATURES FOR THE NEAR TERM. CWA TO REMAIN BENEATH CYCLONIC FLOW ALOFT...WITH WEAK CAA EXPECTED THROUGHOUT THE DAY. SOME LOW LEVEL MOISTURE RESULTING IN AN AREA OF LOW STRATUS CONTINUES TO DEVELOP OFF TO THE NORTHEAST OF THE CWA...WITH MODEL PROGGING THIS AREA OF STRATUS TO CONTINUE TO SPREAD/ADVECT INTO THE NORTHERN/EASTERN HALF OF THE CWA THROUGH SUNRISE. HRRR MODEL AND GOES-R WRF FORECAST BOTH HANDLING THE DEVELOPMENT OF THIS STRATUS WELL AND HAVE TAILORED SKY GRIDS TOWARD THE MODEL/SATELLITE PRODUCT TRENDS. EXPECT STRATUS TO LIFT/BREAK UP TOWARD MID/LATE MORNING ACROSS THE AREA...WITH RESULTANT MID LEVEL CU FIELD POSSIBLE. OTHERWISE MUCH DRIER TO MOVE INTO THE CWA WITH DEWPOINTS EXPECTED TO CONTINUE TO DROP TO AROUND 50 POSSIBLY EVEN INTO THE 40S WITH DRIER AIR MIXING DOWN AND ADVECTING INTO THE CWA IN NORTHERLY FLOW. WITH THE CAA...EXPECT TEMPS TO BE A FEW DEGREES COOLER THAN YESTERDAY WITH HIGHS MAINLY IN THE UPPER 70S TO AROUND 80. .LONG TERM /TONIGHT THROUGH THURSDAY/... CANADIAN HIGH PRESSURE MOVING INTO THE NORTHERN PLAINS EARLY THIS MORNING WITH TEMPERATURES DIPPING INTO THE LOW TO MID 40S OVER THE SOUTHEAST QUADRANT. THIS SYSTEM WILL SETTLE SOUTH TODAY AND BE STRETCHED OVER MUCH OF THE CENTRAL AND NORTHERN PLAINS TONIGHT. WHILE SOME MODIFICATION OF TEMPERATURES IS EXPECTED...SHOULD HAVE OVERNIGHT LOWS TONIGHT TOUCHING THE MID 40S AT A FEW LOCATIONS ACROSS THE NORTH AND INTO THE LOW TO MID 50S ELSEWHERE. THE CLOSED UPPER LOW THAT AFFECTED THE AREA ON THURSDAY WILL BE SHIFTING SLOWLY NORTHEAST ACROSS THE CENTRAL GREAT LAKES THROUGH MID DAY SATURDAY BEFORE GAINING STEAM SATURDAY NIGHT AS ANOTHER CLOSED UPPER LOW MOVES INTO CENTRAL CANADA. THIS WILL ALLOW A TRANSITION TO A MORE PROGRESSIVE NORTHWEST FLOW THAT WILL PERSIST THROUGH MUCH OF THE EXTENDED. A FAIRLY SIGNIFICANT SYSTEM WILL ARRIVE OVER THE PACIFIC NW LATE TODAY THEN MOVE ACROSS THE ROCKIES AND PRODUCE LEE SIDE CYCLOGENESIS INTO SATURDAY. SATURDAY WILL BE ANOTHER PLEASANT DAY AND EXPECT TEMPERATURES TO BE NEAR THE HIGH END OF GUIDANCE WITH DRY SFC AIR HEATING UP EFFICIENTLY. MID LEVEL THETA-E ADVECTION WILL COMMENCE SATURDAY NIGHT WITH THE INITIAL WAVE BEING SPENT ON MID LEVEL SATURATION. GULF MOISTURE WILL BREAK FREE AND BEGIN TO STREAM NORTHWARD SATURDAY NIGHT AS WELL WITH THE MOISTURE ADVECTION ARRIVING LATE AIDED BY AN INCREASING LOW LEVEL JET APPROACHING 40 KTS. THE COMBINATION OF THE MULTI LEVEL KINEMATICS AND THERMODYNAMICS WILL RESULT IN A DEEPLY FORCED SYSTEM WITH SHOWERS AND THUNDERSTORMS ARRIVING OVER THE WEST AFTER MIDNIGHT. ADDITIONAL CHANCES WILL CONTINUE SUNDAY AND SUNDAY NIGHT WITH AS THE SECOND SEGMENT OF THE UPPER LEVEL SYSTEM ARRIVES ALONG WITH THE SFC LOW REFLECTION. GENERAL AGREEMENT DEVELOPING THAT THE SFC LOW WILL SHIFT EAST ACROSS SOUTHERN IA AND WOULD ALLOW A PORTION OF THE WARM SECTOR TO LIFT INTO THE STATE. HIGH VARIABILITY POSSIBLE WITH HIGH TEMPERATURES ON SUNDAY WHERE HIGHS COULD STRUGGLE IN THE 60S UNDER INCREASING CLOUDS AND MORE PROLONGED PRECIPITATION WHILE RISING WELL INTO THE 80S SOUTH WHERE SOME SUN COULD BE POSSIBLE. THIS COULD LEAD TO AN AREA OF SFC BASED THUNDERSTORMS AND AN AREA WITH SEVERE POTENTIAL. PRECIPITATION CHANCES CONTINUE OVER MAINLY THE EAST SUNDAY EVENING BEFORE ENDING. THE REMAINDER OF THE EXTENDED IS HIGHLIGHTED BY SEVERAL IMPULSES RIPPLING THROUGH THE NW FLOW WHILE A DEEP UPPER LEVEL LOW DROPS INTO ALBERTA AND MANITOBA BY MID WEEK. OVERALL TIMING BECOMES DIFFICULT UNDER THESE SITUATIONS BUT GENERAL CONSENSUS IS A WEAK WAVE ARRIVING TUE NIGHT INTO WED WITH A MORE SIGNIFICANT SYSTEM IMPACTING THE AREA TOWARD THE END OF THE PERIOD AS ENERGY ASSOCIATED THE SOUTHERN CANADA SYSTEM ARRIVES. && .AVIATION...10/18Z BAND OF MVFR AND IFR STRATUS WHICH AFFECTED SITES EARLY THIS MORNING WILL CONTINUE TO DIMINISH...LIFTING TO VFR CEILINGS. WINDS WILL BE GUSTY IN THE AFTERNOON BUT WILL DIMINISH NEAR 00Z. HIGH PRESSURE WILL PUSH INTO REGION...WITH WINDS REMAINING PRIMARILY FROM THE NORTH...AND CEILINGS WILL REMAIN VFR THROUGH REMAINDER OF PERIOD. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...BEERENDS LONG TERM...DONAVON AVIATION...AWB
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
450 PM EDT FRI AUG 10 2012 .Forecast Update... Issued at 445 PM EDT Fri Aug 10 2012 Updated the forecast to include 20-30% chance of rain showers over southern Indiana and north central Kentucky this evening. A line of showers moving south across Indiana was noted on radar early this evening, and it looks like the line will hold together into at least northern portions of the area. The 17Z HRRR depicts this line well and shows it dissipating around sunset with the lack of heating/instability. && .Short Term (Today through Saturday)... Issued at 307 PM EDT Fri Aug 10 2012 Surface cold has now cleared our forecast area. Cooler and somewhat drier air continues to mix in from the northwest. The colder air aloft has resulted in steep low-level lapse rates which is resulting in a fairly extensive area of stratocumulus. The stratocu should hang around for the next few hours and then begin to dissipate after sunset. Regional radars do show a few light showers/sprinkles to our north along the I-70 corridor. These will continue to move south and may clip a few of our northern Indiana counties this afternoon before they also dissipate after sunset. Temperatures will likely top off this afternoon in the upper 70s to the lower 80s and then slide off back into the 60s later this evening. For the overnight period, latest suite of model data continue to show plenty of cool air advection across the region. Model-time height cross sections show some low-level moisture lingering across the northeast sections of the forecast area. Probably will see a gradient clouds across the region with mostly clear skies across the west/southwest with partly cloudy skies across the northeast/Bluegrass. As for low temps, we`ll likely see temperatures fall into the mid-upper 50s in the north with upper 50s to the lower 60s in the south. We generally weighted temps closer to the weighted model consensus which has statistically done well. Saturday looks to be a pleasant day across the Ohio Valley with partly to mostly sunny skies as deep northwesterly flow continues across the region. Temperatures will be quite comfortable with highs in the upper 70s in the east with lower 80s in the central and western sections. Mostly clear skies are expected for Saturday Night with lows generally in the mid-upper 50s. .Long Term (Sunday through Friday)... Issued at 300 PM EDT Fri Aug 10 2012 A distinct pattern change will be fully in place by early this weekend. A broad longwave trough is forecast to lie over the upper midwest and the Great Lakes, with ridging pushed farther west across the Intermountain West. No excessive heat or bouts with high humidity are expected for basically the next week as rich Gulf moisture is forecast to remain across the southern states. On Sunday, the deep cyclone now over eastern Michigan is expected to slowly move northeast into Quebec. At the same time, another compact 500mb low will slide southeast across the Missouri Valley. Both the NAM and the GFS forecast weak low pressure to develop over Illinois Monday afternoon and move east across the Commonwealth overnight. Although this system will lack any robust moisture return, upper air divergence associated with the front exit region of the upper jet may provide enough upper air support for scattered thunderstorms during the late Monday through early Tuesday period. High temperatures will warm a bit from Sunday through Monday, with Monday`s highs in the mid to upper 80s expected to nearly match the climatological normal for mid-August. The ECMWF is nearly alone in its forecast of scattered showers on Wednesday. The preferred GFS depicts the Lower Ohio Valley within a a dry northerly flow on the backside of a departing system over western New England. Expect a cooldown once again beginning Tuesday afternoon, with mild temperatures continuing through Thursday. A deep cyclone forecast north of the upper midwest on Thursday will bring a cold front and a chance of storms for late Thursday and Friday. && .Aviation (18Z TAF issuance)... Issued at 104 PM EDT Fri Aug 10 2012 Surface cold front has passed through the terminals this morning. Fairly thick deck of cold air stratocumulus is trailing behind the front and will lead to cigs that remain above VFR thresholds. Northwest winds of 8-10kts will be possible this afternoon at KSDF and KLEX...a gust of 15-17kts will be possible at times. Further south at KBWG, the gradient is a little weaker so only northwesterly winds of 5-8kts is expected. VFR conditions are expected this evening and through much of the overnight hours. There is potential for more low clouds to move back into the region tonight along with the possible development of some patchy fog. KLEX and KBWG seem to be most susceptible to the patchy fog threat with a period of MVFR visibilities being possible between 11/07-13Z. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...NONE. KY...NONE. $$ Update...........AMS Short Term.......MJ Long Term........JSD Aviation.........MJ
AREA FORECAST DISCUSSION
NWS CARIBOU ME
253 PM EDT FRI AUG 10 2012 .SYNOPSIS... A STATIONARY FRONT NEAR THE COAST WILL GRADUALLY MOVE NORTH ACROSS THE REGION AS A WARM FRONT TODAY AND TONIGHT. LOW PRESSURE WILL PASS TO THE WEST OF THE STATE SATURDAY. && .NEAR TERM /THROUGH SATURDAY/... STRONG LOW PRESSURE IS EXPECTED TO MOVE THROUGH THE GREAT LAKES TONIGHT INTO SATURDAY. EXPECT HEAVIER PRECIPITATION ACROSS THE NORTH TONIGHT IN ADVANCE OF PRIMARY LOW THEN FOCUS WILL SHIFT TO COAST SATURDAY AS SECONDARY WAVE DEVELOPS ALONG COAST. FOR POPS HAVE USE THE RUC13 INTO EARLY EVENING THEN TRANSITION OF GFS LATER IN EVENING THEN TO MODEL BLEND OF THE NAM12...GFS40...SREF...CMCREG AND ECMWF. WILL ALSO BLEND THE SAME GUIDANCE FOR QPF EXCEPT USE THE NAM80. WILL MAKE SOME MANUAL ADJUSTMENTS TO SMOOTH PRECIPITATION AREAS. FOR TEMPERATURE AND DEW POINT USED GMOS AND WILL ADJUST MAXIMUM TEMPERATURE A FEW DEGREES HIGHER SATURDAY. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... A CLOSED H5 LOW OVER SOUTHERN QUEBEC OPENS UP AND LIFTS INTO THE NORTHERN CANADIAN MARITIMES. A DISTURBANCE ROTATING AROUND THE H5 LOW COULD BE THE TRIGGER FOR SUNDAY AFTERNOON AND EVENING THUNDERSTORMS. WEATHER CONDITIONS IMPROVE SUNDAY NIGHT AND MONDAY AS THE LOW MOVES TO THE NORTHEAST OF MAINE. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... THE EXTENDED MODELS ARE CONTINUE TO DISAGREE ON A SYSTEM MOVING THROUGH THE MID-WEST AT THE START OF THE PERIOD...HOWEVER ARE IN GOOD GENERAL AGREEMENT ELSEWHERE THROUGH MOST OF THE PERIOD. THE GFS IS SHOWING A LOW PRESSURE SYSTEM OVER ERN QUEBEC WITH ITS FRONT WRAPPED AROUND THE LOW THROUGH NRN ME...THEN OUT ACROSS THE MARITIMES. A WEAK HIGH PRESSURE RIDGE BUILDING NORTH ALONG THE ATLANTIC COAST STATES. A LOW PRESSURE SYSTEM OVER THE SE OF JAMES BAY...WITH A FRONTAL SYSTEM EXTENDING SOUTH THROUGH THE LAKE MICHIGAN...TO A SECOND LOW OVER CHICAGO...THEN SOUTH TO ERN TEXAS. THE ECMWF HAS THE LOW OVER SRN JAMES BAY...A LOW OVER ST LOUIS...ANOTHER OVR ERN TEXAS...IT DOESN`T SUPPORT THE FRONTAL SYSTEM TROUGH THE GREAT LAKES TO ST LOUIS. THE GFS SHOW BETTER UPPER LEVEL SUPPORT WITH A SHORTWAVE DIGGING SOUTH TO NRN LA. THE ECMWF DIGS THE SHRTWV TO SRN MO. TUESDAY MORNING THE GFS DEEPENS THE LOW OVER CHICAGO AND MOVES IT EAST TO DETROIT. MAINTAINS THE FRONT EXTENDING SOUTH TO WRN LA WITH A COUPLE MINOR LOWS. THE ECMWF SHOWS SOME DEVELOPMENT OF THE LOW OVER ST LOUIS...MAINTAINS IT NEARLY STATIONARY. THIS TREND CONTINUE TO TUESDAY EVENING...THE GFS DEEPENS THE LOW FARTHER AND MOVES IT EAST TO THE ERN GREAT LAKES REGION. THE SHORTWAVE TO NRN FL. THE GFS ALSO SHOWING GOOD COLD AIR ALOFT TO SUPPORT THE SFC DEVELOPMENT. THE ECMWF CONTINUE TO SHOW DEVELOPMENT OF THE SYSTEM...NOT TO THE EXTEND OF THE GFS. SHORT WAVE SUPPORT HAS NO SIGNIFICANT CHANGE FROM PREVIOUS. BY WEDNESDAY MORNING THE CONTRAST CONTINUES. THE GFS FURTHER DEEPENS THE LOW OVER THE ERN GREAT LAKES. THE FROTN EXTENDING THROUGH SRN NEW ENGLAND TO A SECOND LOW OVER DELMARVA. A DEEP SHORT WAVE EXTENDING TO NRN FL...THE UPPER RIDGE BUILDING TO SRN HUDSON BAY. THE ECMWF CONTINUE TO SHOW A DISORGANIZED SYSTEM MOVING THROUGH NEW ENGLAND. THE SHORTWAVE TROUGH FILLING....AND NO SIGNIFICANT RIDGE. BOTH MODELS ARE SHOWING A NEW LOW MOVING INTO WRN PLAINS FROM CANADA TO NRN TX. THROUGH THURSDAY EVENING THE GFS MAINTAINS THE LOW OVR THE ERN GREAT LAKES MOVES IT EAST TO SOUTHCOAST...THE SFC AND 500MB LOW VERTICALLY STACKED. A SHARP UPR LVL RIDGE THROUGH THE CNTRL GREAT LAKES. THE NEW LOW EAST TO SRN HUDSON BAY...ITS FRONT SOUTH TO NRN TX. THE ECMWF CONTINUE TO SHOW A DISORGANIZED SYSTEM WITH THE LOW MOVING EAST THROUGH QUEBEC INTO THE WRN MARITIMES BY THURSDAY EVENING. THE NEW LOW THE SAME AS THE GFS. BY END OF PERIOD. THE GFS MAINTAINS THE COLD LOW IN THE GULF OF MAINE...THE ECMWF CONTINUES THE COLD LOW IN THE WRN MARITIMES. THE NEW LOW ON BOTH MODELS OVR SRN HUDSON BAY...WITH A COLD FRONT EXTENDING SOUTH THROUGH THE CNTRL GREAT LAKES. THRU KY...AR...INTO TX. BOTH MODELS SHOW MINOR LOWS ALONG THE BOUNDARY. THE GFS AND ECMWF CONTINUE TO DISAGREE ON THE FIRST SYSTEM...TODAY THERE WAS A MORE PRONOUNCED DIFFERENCES IN THE UPPER LEVEL GUIDANCE THAN IN PREVIOUS RUNS. LOADED GMOS WITH MINOR SMOOTHING OF THE SKY AND POP GRIDS. ADJUSTED POPS DOWN WHERE CLOUD COVER DID NOT SUPPORT PCPN. LOADED NAWAVE 4 FOR SEAS IN THE COASTAL WATERS. PLUS 25 PERCENT TO WNDS FOR GUST OVR COASTAL WATERS...15 PERCENT OVER LAND. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... NEAR TERM: EXPECT IFR CONDITIONS DUE TO LOW CEILINGS NORTH AND LOW CEILING AND FOGS SOUTH. SHORT TERM: IFR/MVFR CIGS AND VSBYS WILL BE POSSIBLE AT TAF SITES SATURDAY NIGHT...EARLY SUNDAY MORNING AND AGAIN SUNDAY NIGHT IN SHOWERS...THUNDERSTORMS AND PATCHY FOG. && .MARINE... NEAR TERM: HAVE BLENDED THE NAM12 AND GFS40 FOR WIND GRIDS THEN REDUCED BLENDED VALUE BY 20 PERCENT TO ADJUST FOR STRONG MARINE LAYER OVER COLDER SEA SURFACE TEMPERATURE. FOR WAVES: SOUTHERLY FETCH AREA TO DEVELOP THIS EVENING SOUTH AND EAST OF NEW ENGLAND. EXPECT THIS AREA TO RESULT IN SOUTHERLY WAVE GROUP 170/7 SECONDS BASE ON WNA SPECTRAL. THINK WNA OVER ESTIMATING THIS GROUP WITH SURFACE WIND TOO HIGH. SECONDARY LONG PERIOD WAVE GROUP FROM 140/9 SECONDS 1-2 FEET VALID BASED ON SPECTRAL DENSITY FROM 44027. WILL USE SWAN/NAM WAVES AND REDUCE BY 1 FOOT THROUGH PERIOD. SHORT TERM: WINDS AND WAVES ARE EXPECTED TO REMAIN BELOW SCA CRITERIA SUNDAY AND MONDAY. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...NONE. MARINE...NONE. && $$ NEAR TERM...MIGNONE SHORT TERM...OKULSKI LONG TERM...NORTON AVIATION...MIGNONE MARINE...MIGNONE/OKULSKI
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
414 PM EDT FRI AUG 10 2012 .SHORT TERM...(THIS EVENING THROUGH SATURDAY) ISSUED AT 410 PM EDT FRI AUG 10 2012 WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL LOW OVER SE LOWER MI. AN EXTENSIVE PCPN SHIELD PERSISTED ON THE NW FLANK OF THE LOW ASSOCIATED WITH THE STRONGER 800-700 MB FGEN/DEFORMATION. TONIGHT...SATELLITE TRENDS AND MODELS KEEP ANY PCPN ASSOCIATED WITH THE SFC/MID LEVEL LOW EAST OF THE CWA.SFC HIGH PRES RIDGE WILL DRIFT E TOWARD UPPER MI TONIGHT...BUT ONLY CLOSE ENOUGH FOR JUST THE FAR W TO SEE LIGHT/CALM WIND AND GOOD RADIATIONAL COOLING CONDITIONS. PWAT VALUES OVER THE WEST FALL INTO THE 0.30 TO 0.50 INCH RANGE. A TIGHTER PRES GRADIENT TO THE EAST WILL MAINTAIN STRONG ENOUGH BNDRY LAYER WINDS TO KEEP TEMPS FROM FALLING OFF AS MUCH. SOME MID OR HIGH CLOUDS OVER THE E WILL ALSO LIMIT TEMP DROP. GUIDANCE TEMPS WERE REASONABLE WITH TEMPS FALLING OFF INTO THE LOWER 40S INLAND WEST...ESPECIALLY IN USUAL COLD SPOTS. SATURDAY...AS THE LOW LIFTS SLOWLY TO THE NE THROUGH SRN ONTARIO...NRLY WINDS WILL ONLY GRADUALLY DIMINISH. WITH 850 MB TEMPS AROUND 9C...MAX READINGS INTO THE LOWER TO MID 70S ARE EXPECTED. FCST SOUNDINGS AND DEEPER MIXING SHOW POTENTIAL FOR DEWPOINTS TO DRAMATICALLY(AOB 40)INLAND. SO...ADJUSTED DEWPOINTS TOWARD LOWER END NAM GUIDANCE WITH AT LEAST LOWER 40S WITH MIN RH VALUES AOB 35 PCT. A HIGH RISK OF RIP CURRENTS REMAINS TONIGHT INTO SATURDAY. .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY) ISSUED AT 410 PM EDT FRI AUG 10 2012 THE LATE SUMMER PATTERN WILL BE IN FULL SWING THROUGH THE LONG TERM AS DEEP TROUGHING SLOWLY DEVELOPS OVER EASTERN CANADA. AS A RESULT...A SIGNIFICANT COOL-DOWN LATE NEXT WEEK IS APPEARING MORE LIKELY WITH EACH PASSING DAY. SATURDAY NIGHT THROUGH MONDAY...THE STACKED CLOSED LOW THAT IS BRINGING HEAVY PRECIPITATION TO PORTIONS OF LOWER MI TODAY WILL CONTINUE DRIFTING NORTHEAST THROUGH SATURDAY...EVENTUALLY REACHING GEORGIAN BAY BY 00Z SUNDAY. BOTH THE NAM AND GFS CONTINUE TO INDICATE AN ENHANCED BAND OF H7 DEFORMATION PUSHING NW INTO FAR EASTERN UPPER MI...WITH THE NAM BEING THE MOST AGGRESSIVE. BUT GIVEN THAT THE NAM HAS OVERDONE MOISTURE WITH THIS SYSTEM AND THAT THERE WILL BE SIGNIFICANT DRY AIR IN PLACE ABOVE 800 MB...DO NOT THINK ANY PRECIP WILL MAKE IT INTO THE CWA. A BRIEF SHORTWAVE RIDGE WILL THEN MOVE ACROSS THE AREA LATE SATURDAY NIGHT INTO SUNDAY AND BRING MOSTLY CLEAR SKIES. SOME HIGH CLOUDS MAY REMAIN OVER THE EAST HALF AS A RESULT OF THE LEFT ENTRANCE TO A WEAK UPPER JET ON THE BACKSIDE OF THE DEPARTING MID-LEVEL LOW. TEMPS COULD FALL A DECENT AMOUNT ACROSS THE INTERIOR WEST HALF WITH LIGHT WINDS...VERY DRY AIR...AND MINIMAL CLOUD COVER. HAVE DROPPED TEMPS INTO THE LOWER FOR SOME OF THE NORMAL COLD SPOTS. AS MENTIONED IN THE PREVIOUS FORECAST...IT APPEARS A CONVECTIVELY INDUCED SHORTWAVE WILL DEVELOP SATURDAY NIGHT ACROSS THE NORTHERN PLAINS. THIS WAVE IS PROGGED TO ERODE THE RIDGE AND MOVE SOUTHEAST INTO SOUTHERN MN/NORTHERN IA BY 00Z MONDAY. MEANWHILE...A LARGER MID-LEVEL TROUGH OVER NORTHERN SASKATCHEWAN AT 00Z SUNDAY WILL MOVE TO THE EAST THROUGH THE WEEKEND...REACHING FAR NORTHERN QUEBEC BY 18Z MONDAY. AN EXTENSION OF THIS TROUGH AND AN ASSOCIATED COLD FRONT SHOULD TRACK ACROSS THE CWA MONDAY AS IT PICKS UP THE SHORTWAVE IN THE UPPER MISSISSIPPI VALLEY. THE ECMWF HAS TRENDED MUCH FASTER WITH THE TROUGH OVER THE PAST FEW RUNS...WHILE THE GFS HAS ACTUALLY SLOWED THE TROUGH. FOR NOW...WILL STICK WITH THE IDEA THAT IT WILL COME THROUGH SOMETIME ON MONDAY...BEGINNING WITH THE WEST IN THE MORNING AND ENDING WITH THE EAST IN THE LATE AFTERNOON. THE TROUGH WILL BE STARVED OF LOW-LEVEL MOISTURE AS THE CONVECTIVE COMPLEX TO THE SOUTH SHOULD PREVENT MOST NORTHWARD FLOW OF MOISTURE. SOME SUNSHINE WILL MAKE IT THROUGH THE CLOUDS...ALLOWING SBCAPE VALUES TO REACH A FEW HUNDRED J/KG. EXTRA LIFTING SUPPORT FROM WEAK LAKE BREEZES WILL LIKELY ALLOW SOME ISOLATED TO SCATTERED SHOWERS AND A FEW THUNDERSTORMS TO DEVELOP INLAND...MAINLY IN THE AFTERNOON. THIS ACTIVITY WILL SPREAD EASTWARD ALONG THE FRONT BEFORE CLEARING OUT EARLY MONDAY EVENING. DEW POINTS WILL BE A CONCERN ON SUNDAY WITH ABUNDANT SUNSHINE AND A SHARP TRANSITION TO DRY AIR ABOVE THE MIXED LAYER. FORECAST H8 DEW POINTS ARE AROUND 8C...BUT QUICKLY DROP TO -10 TO -20C BY H7. WINDS WILL BE LIGHT THOUGH...SO DECENT ENTRAINMENT OF THE DRY AIR MAY BE LIMITED. WILL LOWER DEW POINTS TO THE UPPER 40S INTERIOR WEST IN THE AFTERNOON. MONDAY NIGHT THROUGH WEDNESDAY...A MID-LEVEL RIDGE WILL BEGIN TO BUILD IN FROM THE WEST MONDAY NIGHT AND BRING MOSTLY CLEAR SKIES THROUGH WEDNESDAY. POPS WERE REMOVED WEDNESDAY AS THE ECMWF...WHICH HAD POPS IN THE FORECAST YESTERDAY...HAS LINED UP WITH THE GFS IN SHARPENING THE RIDGE AND KEEPING THE AREA DRY. MORE ABUNDANT MIXING DAYS COULD BE IN STORE TUESDAY AND WEDNESDAY AS VERY DRY AIR REMAINS ABOVE THE MIXED LAYER. WEDNESDAY WILL BE OF MORE CONCERN AS TEMPERATURES WILL RISE TO AROUND 80 AND DEW POINTS WILL POSSIBLY FALL WELL INTO THE 50S. AS OF NOW...FORECAST MIN RH VALUES WILL BE IN THE LOW 40S FOR THE INTERIOR WEST. HOWEVER...MIXING MAY BE EVEN MORE AGGRESSIVE THAN CURRENTLY FORECAST...SO RH VALUES MAY FALL INTO THE 30S. WINDS WILL REMAIN RATHER LIGHT...LESS THAN 15 MPH...SO FIRE WX CONCERNS ARE LIMITED RIGHT NOW. WEDNESDAY NIGHT AND FRIDAY...A SIGNIFICANT CHANGE IN THE WEATHER PATTERN APPEARS TO BE IN THE MAKING WEDNESDAY NIGHT. A SHORTWAVE TROUGH CURRENTLY OVER THE GULF OF ALASKA WILL MOVE EAST THROUGH THE SOUTHERN CANADIAN PROVINCES THROUGH THE WEEKEND WHILE PICKING UP ENERGY AND MUCH COOLER H8 AIR FROM A POLAR VORTEX WEST OF GREENLAND. GUIDANCE IS RATHER CONSISTENT WITH THE HANDLING OF THIS TROUGH THROUGH WEDNESDAY NIGHT...BUT SOLUTIONS BEGIN TO DIVERGE BY THURSDAY. THE ECMWF AND GEM BRING THE TROUGH NORTHEASTWARD MUCH QUICKER THAN THE GFS. THE ECMWF THEN TRIES TO DEVELOP A CLOSED LOW OVER THE CWA ON FRIDAY...RESULTING IN PLENTY OF RAIN. SOLUTIONS ARE MUCH TOO INCONSISTENT AND DIVERGENT AT THIS POINT TO MAKE ANY SENSE OF TIMING AND PRECIP...BUT ALL STILL HINT AT A MUCH COOLER END TO THE WEEK...WITH HIGHS POSSIBLY AROUND 60 IN SOME PLACES ON FRIDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 159 PM EDT FRI AUG 10 2012 MVFR CEILINGS AT KSAW WITH UPSLOPE WINDS WILL GIVE WAY TO VFR CONDITONS DURING THE AFTERNOON WHEN BNDRY LAYER DRYING BECOMES MORE SIGNIFICANT. OTHERWISE...VFR CONDITIONS WILL PREVAIL FOR THE REST OF THE FCST PERIOD. WINDS WILL BE GUSTY TODAY...ESPECIALLY AT KSAW WHERE GUSTS TO AROUND 25KT ARE EXPECTED DUE TO FAVORABLE WIND DIRECTION AND CLOSER PROXIMITY TO DEPARTING SYSTEM. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 410 PM EDT FRI AUG 10 2012 EXPECT THE STRONGEST WINDS DURING THE FCST PERIOD TO OCCUR TONIGHT THROUGH SAT UNDER RELATIVELY TIGHT PRES GRADIENT BTWN LOW PRES DRIFTING NNE INTO SRN ONTARIO AND HIGH PRES DRIFTING E TOWARD THE UPPER LAKES. CLOSER TO APPROACHING HIGH...WINDS WILL BE LIGHTEST OVER WRN LAKE SUPERIOR... GENERALLY 10-20KT. OVER THE E...NNE WINDS WILL BE MOSTLY IN THE 15-25KT RANGE. WINDS WILL SLOWLY DIMINISH TONIGHT INTO SAT...BUT WINDS WILL REMAIN AOA 20 KT OVER ERN LAKE SUPERIOR TIL LATE SAT. WINDS SUN THRU TUE WILL BE MOSTLY 15KT OR LESS AS ONLY WEAK SYSTEMS AFFECT THE AREA. A FALL-LIKE LOW PRESSURE SYSTEM AND FRONT MOVING THROUGH LAKE SUPERIOR THURSDAY INTO FRIDAY COULD BRING STRONGER NW WINDS INTO THE 20-30 KT RANGE. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLB LONG TERM...TK AVIATION...JLB MARINE...JLB
AREA FORECAST DISCUSSION
NWS RALEIGH NC
206 PM EDT FRI AUG 10 2012 .SYNOPSIS... A STRONG COLD FRONT WILL APPROACH OUR REGION FROM THE WEST TODAY AND TONIGHT...THEN CROSS CENTRAL NORTH CAROLINA SATURDAY AND SATURDAY NIGHT. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1030 AM FRIDAY... SKIES ARE OVERCAST WITH WIDESPREAD STRATUS THIS MORNING..BETWEEN AN UPPER DISTURBANCE AND ASSOCIATED PRECIP DEPARTING TO THE NORTHEAST...AND TWO MORE APPROACHING FROM BOTH THE NORTHWEST AND SOUTHWEST LATER TODAY. A FEW LIGHT SHOWERS ARE MOVING THROUGH THE PIEDMONT THIS MORNING...BUT OVERALL THERE IS A LULL ACROSS THE CAROLINAS BETWEEN THE AFOREMENTIONED UPPER FEATURES. AN UPPER LOW/SURFACE CYCLONE HAVE NOW DEVELOPED OVER THE GREAT LAKES AND THE ASSOCIATED COLD FRONT EXTENDS SOUTH THROUGH OH/KY/TN....WITH A STREAM OF 2 INCH PWS ACROSS THE NC/SC PIEDMONT AND COASTAL PLAIN. A LINE OF PREFRONTAL CONVECTION IS CURRENTLY MOVING THROUGH EASTERN TN AND WV...BUT THE DEEP LAYER FLOW IS FORECAST TO BECOME MORE SOUTHWESTERLY AS THE UPPER TROUGH CONTINUES TO DEEPEN... AND THE PROGRESSION OF CONVECTIVE LINE SHOULD SLOW AS IT CROSSES THE MOUNTAINS THIS MORNING. IN FACT... HRRR FORECASTS SHOW A LINE OF CONVECTION MOVING INTO THE WESTERN PIEDMONT CLOSER TO 00Z. MEANWHILE...THE AFOREMENTIONED DISTURBANCE NEAR THE GULF COAST SHOULD BE DRAWN NORTH-NORTHEASTWARD...APPROACHING THE SOUTHERN CWA BY 00Z. WHILE A FEW SHOWERS AND STORMS WILL BE POSSIBLE THROUGH MID AFTERNOON WITH WEAK DISTURBANCES IN THE MOIST SOUTHWESTERLY FLOW ALOFT...WE SHOULD BE ABLE TO PUSH MORE SIGNIFICANT POPS BACK UNTIL AFTER 21-22Z. CONCERNING THE SEVERE THREAT THROUGH THIS EVENING...IT APPEARS THE WIDESPREAD STRATUS MAY LINGER THROUGH MIDDAY...WITH MORNING PIREPS CONTINUING TO REPORT 3K FT DEPTH TO THE STRATUS. VISIBLE IMAGERY SHOWS MORE PROMINENT BREAKS IN THE CLOUDS OVER WESTERN NC AND OVER THE COASTAL PLAIN. THUS...TWO INSTABILITY AXES MAY DEVELOP IN THESE REGIONS...AND MODELS SUGGEST 1500 J/KG OR MORE OF MLCAPE POSSIBLE..WITH VALUES AROUND 1000 J/KG OVER THE PIEDMONT. STRONGER DEEP LAYER SHEAR WILL BE LOCATED WEST OF THE MOUNTAINS FOR MOST OF THE DAY...ALTHOUGH THE MID LEVEL HEIGHT GRADIENT WILL BEGIN TO STRENGTHEN THIS EVENING...AND THE RAP SHOWS 25-35KT OF 0-6KM BULK SHEAR DEVELOPING OVER THE WESTERN PIEDMONT. TO THE EAST...WHERE DEEP LAYER FLOW IS A BIT WEAKER...MORE LIKE 20-25KT OF DEEP BULK SHEAR...MORNING RAOBS SUGGEST A BELT OF 30KT 925-850MB FLOW EXISTS AND THE SPC MESOANALYSIS CURRENTLY SHOWS AN AXIS OF 20KT 0-1KM SHEAR OVER THE COASTAL PLAIN. SO WHILE DEEP SHEAR MAY NOT SUPPORT SUPERCELLULAR ACTIVITY... IT IS POSSIBLE THAT A FEW CLUSTERS OF STORMS OR EVEN DISCRETE CELLS WITH WEAK ROTATION COULD DEVELOP THIS EVENING. THIS IS ALL SIGNIFICANTLY DEPENDENT ON OUR DIURNAL DESTABILIZATION AND WHETHER OR NOT CONVECTION CAN HOLD TOGETHER SINCE THE MAIN FORCING MECHANISMS WILL NOT ARRIVE UNTIL CLOSER TO 00Z. OTHERWISE...HAVE MADE SOME MINOR ADJUSTMENTS TO AFTERNOON HIGHS...WITH SLIGHTLY HIGHER VALUES OVER THE EASTERN AND WESTERN AREAS...BUT GENERALLY 84-87 SHOULD STILL BE ATTAINABLE IF BREAKS IN CLOUDS DEVELOP BY MID AFTERNOON. -SMITH TONIGHT...SW FLOW WILL DEEPEN OVER CENTRAL NC IN RESPONSE TO AMPLIFYING TROUGH OVER THE EASTERN LAKES-OH VALLEY. THIS SUGGEST A THREAT FOR SHOWERS-STORMS TO TRAIN REPEATEDLY ACROSS THE SAME LOCATIONS. SINCE FLOW WILL BE TAPPING AN AIR MASS WITH A VERY HIGH MOISTURE CONTENT OVER THE NORTHERN GULF...COULD SEE A MODERATE FLASH FLOOD THREAT DEVELOP OVER CENTRAL NC OVERNIGHT. MODEL GUIDANCE DEPICT BEST LIFT ALOFT IN ASSOCIATION WITH THE UPPER JET WHILE LIFT BELOW 700MB WEAK AT BEST. THUS PLAN TO HAVE POPS NO HIGHER THAN 70-80 PERCENT OVER THE WEST HALF OVERNIGHT...TRENDING TO NEAR 60 PERCENT SE (WHICH MAY BE GENEROUS). TEMPS TODAY DEPENDENT ON THE AMOUNT OF SUN THAT OCCURS. EXPECT CONDITIONS TODAY SIMILAR TO THE PAST FEW DAYS WHERE MAX TEMPS IN THE MID 80S COMMON. MIN TEMPS TONIGHT UPPER 60S TO LOWER 70S. && .SHORT TERM /SATURDAY AND SATURDAY NIGHT/... AS OF 315 AM FRIDAY... SATURDAY...EXPECT SCATTERED CONVECTION TO BE ONGOING ACROSS CENTRAL NC SATURDAY MORNING. AS AIR MASS BECOMES MARGINALLY UNSTABLE IN THE AFTERNOON AND SURFACE COLD FRONT ENTERS THE MOUNTAINS...SHOULD SEE AN UPTICK IN CONVECTIVE COVERAGE IN THE AFTERNOON. BULK SHEAR VALUES 30-35KTS ACROSS THE ENTIRE FORECAST AREA SUGGEST DECENT POTENTIAL FOR ORGANIZED STORMS IN THE FORM OF BROKEN LINE SEGMENTS THOUGH INSTABILITY MAY BE LACKING FOR SEVERE STORMS DUE TO LIMITED INSOLATION CAUSED BY CONSIDERABLE CLOUDINESS AND SCATTERED SHOWERS. IF PARTIAL SUN OCCURS IN THE LATE MORNING INTO THE AFTERNOON...PROBABILITY FOR SEVERE STORMS WILL INCREASE EXPONENTIALLY. AGAIN...DUE TO TAP OF TROPICAL MOISTURE AND DEEP SW FLOW...COULD SEE SHOWERS-STORMS TRAIN NEWD ACROSS THE REGION...LEADING TO POSSIBLE FLASH FLOODING EPISODE. MAX TEMPS MAINLY IN THE MID 80S THOUGH IF SHOWERS MORE WIDESPREAD...COULD SEE MAX TEMPS 3-5 DEGREES COOLER...ESPECIALLY WEST HALF. WITH PASSAGE OF LOW-MID TROUGH SATURDAY EVENING IN THE WEST...EXPECT CHANCES FOR CONVECTION TO BEGIN TO DECREASE IN THIS REGION. MEANWHILE DECENT CHANCES FOR SCATTERED SHOWERS-STORMS SHOULD PERSIST THROUGH MIDNIGHT IN THE EAST. MIN TEMPS MID 60S NW TO NEAR 70-LOWER 70S SE. && .LONG TERM /SUNDAY THROUGH THURSDAY/... AS OF 245 AM FRIDAY... MID/UPPER LOW EXPECTED TO BE CENTERED INVOF THE NORTHERN GREAT LAKES REGION AND NEAR THE ONTARIO/QUEBEC BORDER 12Z SUNDAY IS EXPECTED TO CONTINUING LIFTING NNE ON SUNDAY. THIS WILL RESULT IN FLOW ALOFT ACROSS CENTRAL NC BECOMING MORE WESTERLY WITH DRIER AIR ALOFT CONTINUING TO FILTER INTO THE AREA. AT THE SURFACE THE WEAK FRONT IS EXPECTED TO WASHOUT/DISSIPATE ACROSS THE AREA ON SUNDAY INTO MONDAY. GIVEN THIS ALONG WITH THE DEPARTURE OF THE FORCING ALOFT AND MOIST AIR ALOFT... EXPECTED GENERALLY DRY CONDITIONS ON SUNDAY INTO MONDAY (OUTSIDE OF POSSIBLE A FEW LINGERING SHOWERS/STORMS ACROSS THE FAR EAST ON SUNDAY... SLIGHT CHANCE AT BEST THOUGH). CHANCE FOR POPS ARE EXPECTED TO INCREASE BY TUESDAY INTO TUESDAY NIGHT/PERHAPS LINGERING INTO WEDNESDAY/THURSDAY AS A LOW AMPLITUDE S/W TROUGH AND ASSOCIATED WEAK COLD FRONT/SURFACE TROUGH MOVE ACROSS THE AREA. GIVEN TIMING AND SOME STRENGTH DIFFERENCES WILL CONTINUE TO ONLY GO WITH A LOW END CHANCE POPS FOR TUESDAY/TUESDAY EVENING... WITH DIURNAL SLIGHT CHANCE POPS FOR WEDNESDAY INTO THURSDAY WITH THE REMNANT LINGERING SURFACE TROUGH. HIGH TEMPS DURING THE PERIOD ARE EXPECTED TO GENERALLY BE IN THE UPPER 80S TO LOWER 90S... WITH LOWS GENERALLY RANGING FROM THE UPPER 60S TO LOWER 70S (WITH MAYBE SOME LOW TEMPS IN THE LOWER TO MID 60S IN THE RURAL LOCATIONS AND NORTHWEST PIEDMONT ON MONDAY MORNING). && .AVIATION /18Z FRIDAY THROUGH TUESDAY/... AS OF 200 PM FRIDAY... LINGERING MVFR CEILINGS ACROSS CENTRAL NC WILL CONTINUE TO THIN OUT AND IMPROVE TO VFR BY 19 TO 20Z. AIRMASS WILL THEN DESTABILIZE...SUPPORTING SCATTERED SHOWERS AND STORMS BETWEEN 20 TO 24Z...PARTICULARLY IN THE VICINITY OF KFAY AND KRWI WHERE LEAD SHORTWAVE DISTURBANCE RESIDES. CONVECTIVE MIXING WILL ALSO RESULT IN OCCASIONAL BREEZY SWLY WINDS BETWEEN 15 TO 18KTS. A SFC FRONT WILL PUSH EAST OF THE MTNS BETWEEN 03Z-06Z TONIGHT. WESTERN PORTIONS OF THE FORECAST AREA...INCLUDING THE TRIAD TERMINALS...ARE EXPECTED TO SEE BETTER CONVECTIVE RAIN CHANCES WITH THE APPROACH OF THE FRONT. THE FRONT WILL THEN MOVE SLOWLY THROUGH THE AREA SATURDAY AND SATURDAY EVENING. EXPECT BANDS OF SHOWERS AND T-STORMS ACROSS CENTRAL NC THROUGH 18Z SATURDAY WITH ASSOCIATED MVFR CONDITIONS. DRIER MORE STABLE AIR WILL GRADUALLY OVERSPREAD CENTRAL NC LATE SATURDAY NIGHT INTO SUNDAY LEADING TO IMPROVING AVIATION CONDITIONS. MAINLY VFR CONDITIONS EXPECTED MONDAY INTO TUESDAY. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...WSS NEAR TERM...WSS/SMITH SHORT TERM...WSS LONG TERM...BSD AVIATION...CBL
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
537 PM EDT FRI AUG 10 2012 .SYNOPSIS... A COLD FRONT WILL APPROACH FROM THE WEST THIS AFTERNOON AND SHOULD GET HUNG UP ACROSS THE MOUNTAINS TONIGHT. THE FRONT IS EXPECTED TO PUSH THROUGH LATE SATURDAY AND THEN SOUTH OF THE AREA ON SUNDAY. HIGH PRESSURE WILL MOVE IN FOR THE EARLY PART OF NEXT WEEK. MEANWHILE ANOTHER FRONT WILL APPROACH THE AREA BY MID WEEK. && .NEAR TERM /THROUGH SATURDAY/... AS OF 530 PM...A STRONG STORM HAS MOVED INTO RABUN COUNTY...AND A LINE OF CONVECTION IS ORGANIZING OVER THE GREAT VALLEY OF TN. HOWEVER...NOT MUCH IS HAPPENING OVER THE ERN FOOTHILLS AND PIEDMONT ZONES ATTM AND I/VE CUT BACK POPS IN THOSE LOCATIONS FOR THE NEXT COUPLE HOURS. THERE CONTINUES TO BE GOOD MODEL AGREEMENT THAT CONVECTION WILL BECOME MORE WIDESPREAD THROUGH BOTH AN MCS MOVING INTO THE NC MTNS AND CONVECTION DEVELOPING IN STRENGTHENING LLVL CONVERGENCE ACROSS THE FOOTHILLS LATER THIS EVENING. AND THIS IS REFLECTED WELL IN THE GRIDS. AS OF MID AFTERNOON...VISIBLE SATELLITE IMAGERY SHOWS LOW CONVECTIVE CLOUDS SCATTERING SUFFICIENTLY E OF THE BLUE RIDGE TO ALLOW HEATING THAT HAS RAISED SFC-BASED CAPE INTO THE 1500-2000 J/KG RANGE ON THE LAPS ANALYSIS. SHOWER ACTIVITY HAS DEVELOPED OVER THE CLT METRO AREA AND ALONG THE BLUE RIDGE...WITH MORE ACTIVITY CLOSER TO THE FRONT OVER THE CUMBERLAND PLATEAU. EXPECT SHOWERS AND STORMS TO CONTINUE DEVELOPING AND BECOMING MORE NUMEROUS...MAINLY OVER THE MTNS AND FOOTHILLS...THROUGH THE LATE AFTERNOON. SEVERE WEATHER REMAINS A CONCERN WITH SOME DRY AIR ABOVE 500 MB...ALTHO IN GENERAL THE SOUNDINGS DO NOT LOOK AS FAVORABLE AS YESTERDAY. OVER THE NEXT 24 HOURS OR SO...THE MODELS ARE IN GOOD AGREEMENT WITH THE EVOLUTION OF WEATHER FEATURES...AND IN PARTICULAR SHOW THE AXIS OF THE UPPER TROF AND THE UPPER JET REMAINING TO OUR WEST. THIS WILL ACT TO KEEP THE SURFACE FRONT HUNG UP PROBABLY OVER THE MTNS THROUGH SATURDAY AFTERNOON. THE TREND...THEREFORE...IS TO HOLD ON TO MORE OF A CHANCE OF SHOWER/TSTM ACTIVITY OVER A LARGER PART OF THE FCST AREA THROUGH 00Z SUNDAY. THE THREAT OF SEVERE STORMS WILL SLOWLY INCREASE AS BUOYANCY AND DCAPE SLOWLY BECOME MORE FAVORABLE...WITH JUST ENOUGH SHEAR TO PERHAPS ORGANIZE STORMS EARLY THIS EVENING. THE 4KM WRF DEVELOPS A LINE OF STORMS OFF THE BLUE RIDGE AROUND 23Z WHILE THE HRRR BRINGS THE LINE OF STORMS ACROSS TN AND INTO THE NC MTNS AROUND THAT TIME. ABUNDANT LOW LEVEL MOISTURE AND ENUF UPPER FORCING WILL EXIST TO WARRANT A LIKELY POP INTO THE EVENING HOURS. WILL KEEP POP IN THE CHANCE RANGE OVERNIGHT AS ADDITIONAL STORMS COULD REDEVELOP AT ANY TIME WITH THE SITUATION REMAINING UNCHANGED. TEMPS WILL REMAIN MILD. ON SATURDAY...EXPECT THE FRONT TO BE HUNG UP OVER THE MTNS AT SUNRISE. UNLESS EXTENSIVE CONVECTIVE DEBRIS PREVENTS IT...CONVECTION SHOULD RE-FIRE EARLY IN THE DAY CLOSE TO THE FRONT AS IT DID TO OUR WEST THIS PAST MORNING. UPPER DIVERGENCE...DPVA...AND PLENTY OF MOISTURE SUGGEST ANOTHER POP IN THE LIKELY RANGE BY AFTERNOON OVER THE PIEDMONT...AND A CHANCE UP TO THE BLUE RIDGE. A GUIDANCE BLEND WAS USED FOR HIGH TEMPS. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... AT 200 PM EDT FRIDAY...12Z GFS AND NAM STILL SOMEWHAT AT ODDS AS TO HOW FAST THE FRONTAL BAND OF DEEP LAYER MOISTURE AND PRECIP WILL EXIT THE FORECAST AREA OVER THE EAST. THE NAM STIL IS FASTER AND HAS THE DEEP LAYER FRONTAL MOISTURE EAST OF THE AREA BY 00Z SUN...WHILE THE GFS IS CONSIDERABLY SLOWER AND WETTER. THE SREF APPEARS TO CONTINUE TO BE A GOOD COMPROMISE FOR THE SOLUTION. THE SREF KEEPS PRECIP CHANCES OVER THE EASTERN MOST PART OF THE FORECAST AREA EARLY ON SAT NIGHT...AND THEN MOVES THE MOISTURE/PRECIP EAST BY MIDNIGHT. WILL ALSO SCATTER AND CLEAR THE CLOUDS FROM NW TO SE SAT NIGHT. HIGH PRESSURE BUILDS OVER THE AREA ON SUN WHICH SHOULD PRODUCE A VERY NICE DAY WITH DEWPOINTS MIXING OUT INTO THE 50S OVER THE MOUNTAINS AND LOW 60S ELSEWHERE. THE HIGH SHIFTS EAST OF THE AREA ON MONDAY...BUT ITS LINGERING INFLUENCE SHOULD ALLOW FOR ANOTHER DRY DAY ON MONDAY. TEMPS ARE EXPECTED TO BE SLIGHTLY BELOW CLIMO ON SUN AND NEAR CLIMO ON MON. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... AT 130 PM EDT FRIDAY...A SOMEWHAT PROGRESSIVE PATTERN APPEARS TO BE IN STORE DURING THE MEDIUM RANGE. THE UPPER AIR PATTERN WILL GENERALLY FEATURE A MEAN TROUGH OVER THE EASTERN U.S. WITH INDICATIONS FROM THE LATEST 12Z GFS OF BUILDING HEIGHTS TOWARD THE END OF NEXT WEEK OVER THE EAST. LATEST HPC/GFS GUIDANCE SUGGESTS A WEAK COLD FRONT WILL CROSS THE REGION ON TUE ALONG WITH SCATTERED CONVECTION. THE GFS DRIVES THE FRONT SE OF THE AREA BY WED WITH HIGH PRESSURE BUILDING IN THROUGH THU. THUS ONLY CLIMO TYPE POPS FOR AFTERNOON CONVECTION IN THE MOUNTAINS WED AND THU. ANOTHER FRONT APPROACHES THE AREA ON FRI AND PER HPC WILL FORECAST CHANCE TYPE POPS. TEMPS SHOULD BE NEAR CLIMO THROUGH THE PERIOD. && .AVIATION /22Z FRIDAY THROUGH WEDNESDAY/... AT KCLT...SCATTERED SHOWERS DEVELOPING RAPIDLY OVER THE WRN PIEDMONT WHILE CLOUD BASES REMAIN MVFR. THIS SHOULD CONTINUE WITH A SLOW RISE IN THE LCL THROUGH EARLY AFTERNOON...SUCH THAT CONDITIONS SHOULD BECOME VFR BY 20Z. LOW CLOUDS WILL CONTINUE...HOWEVER...THROUGH THE REST OF THE DAYLIGHT HOURS GIVEN THE PLENTIFUL LOW LEVEL MOISTURE. THE LATEST GUIDANCE SUGGESTS THE BEST CHANCE FOR ANOTHER ROUND OF THUNDERSTORMS WILL BE EARLY THIS EVENING. THERE IS ENUF FORCING TO SUGGEST THAT STORMS ARE LIKELY...SO THE TARGET WINDOW OF 01Z TO 04Z HAS BEEN ESTABLISHED. SOME SHOWERS COULD CONTINUE OVERNIGHT WITH THE ACTUAL FRONT HUNG UP TO THE WEST. LOW CLOUDS SHOULD RETURN LATE TONIGHT...RESULTING IN AT LEAST AN MVFR CEILING AFTER 11Z. MORE LOW CLOUDS ARE POSSIBLE AGAIN SATURDAY MORNING WITH THE FRONT HUNG UP OVER THE MTNS. ELSEWHERE...LOW CLOUDS CONTINUE TO SCATTER OUT EARLY THIS EVENING... WHICH WILL FINALLY ALLOW FOR SOME DESTABILIZATION. SHOWERS WILL CONTINUE TO DEVELOP ACROSS THE MTNS THROUGH 22Z AND THEN PUSH EAST THROUGH THE EARLY EVENING. RETURN TO LOW MVFR/IFR CIGS TONIGHT AS FRONT SLOWS...IFR VSBY POSSIBLY MAINLY ACROSS KHKY AND KAVL WHERE DRY AIR ALOFT WORKS IN. OUTLOOK...A COLD FRONT WILL SLOWLY CROSS THE AREA LATE SATURDAY... WITH DRIER HIGH PRES BUILDING IN FROM THE W THE LATTER HALF OF THE WEEKEND. WEAK HIGH PRESSURE WILL LINGER THROUGH EARLY NEXT WEEK. AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)... WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...PM NEAR TERM...MCAVOY SHORT TERM...LG LONG TERM...LG AVIATION...PM
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
241 PM EDT FRI AUG 10 2012 .SYNOPSIS... A COLD FRONT WILL APPROACH FROM THE WEST THIS AFTERNOON AND SHOULD GET HUNG UP ACROSS THE MOUNTAINS TONIGHT. THE FRONT IS EXPECTED TO PUSH THROUGH LATE SATURDAY AND THEN SOUTH OF THE AREA ON SUNDAY. HIGH PRESSURE WILL MOVE IN FOR THE EARLY PART OF NEXT WEEK. MEANWHILE ANOTHER FRONT WILL APPROACH THE AREA BY MID WEEK. && .NEAR TERM /THROUGH SATURDAY/... AS OF MID AFTERNOON...VISIBLE SATELLITE IMAGERY SHOWS LOW CONVECTIVE CLOUDS SCATTERING SUFFICIENTLY E OF THE BLUE RIDGE TO ALLOW HEATING THAT HAS RAISED SFC-BASED CAPE INTO THE 1500-2000 J/KG RANGE ON THE LAPS ANALYSIS. SHOWER ACTIVITY HAS DEVELOPED OVER THE CLT METRO AREA AND ALONG THE BLUE RIDGE...WITH MORE ACTIVITY CLOSER TO THE FRONT OVER THE CUMBERLAND PLATEAU. EXPECT SHOWERS AND STORMS TO CONTINUE DEVELOPING AND BECOMING MORE NUMEROUS...MAINLY OVER THE MTNS AND FOOTHILLS...THROUGH THE LATE AFTERNOON. SEVERE WEATHER REMAINS A CONCERN WITH SOME DRY AIR ABOVE 500 MB...ALTHO IN GENERAL THE SOUNDINGS DO NOT LOOK AS FAVORABLE AS YESTERDAY. OVER THE NEXT 24 HOURS OR SO...THE MODELS ARE IN GOOD AGREEMENT WITH THE EVOLUTION OF WEATHER FEATURES...AND IN PARTICULAR SHOW THE AXIS OF THE UPPER TROF AND THE UPPER JET REMAINING TO OUR WEST. THIS WILL ACT TO KEEP THE SURFACE FRONT HUNG UP PROBABLY OVER THE MTNS THROUGH SATURDAY AFTERNOON. THE TREND...THEREFORE...IS TO HOLD ON TO MORE OF A CHANCE OF SHOWER/TSTM ACTIVITY OVER A LARGER PART OF THE FCST AREA THROUGH 00Z SUNDAY. THE THREAT OF SEVERE STORMS WILL SLOWLY INCREASE AS BUOYANCY AND DCAPE SLOWLY BECOME MORE FAVORABLE...WITH JUST ENOUGH SHEAR TO PERHAPS ORGANIZE STORMS EARLY THIS EVENING. THE 4KM WRF DEVELOPS A LINE OF STORMS OFF THE BLUE RIDGE AROUND 23Z WHILE THE HRRR BRINGS THE LINE OF STORMS ACROSS TN AND INTO THE NC MTNS AROUND THAT TIME. ABUNDANT LOW LEVEL MOISTURE AND ENUF UPPER FORCING WILL EXIST TO WARRANT A LIKELY POP INTO THE EVENING HOURS. WILL KEEP POP IN THE CHANCE RANGE OVERNIGHT AS ADDITIONAL STORMS COULD REDEVELOP AT ANY TIME WITH THE SITUATION REMAINING UNCHANGED. TEMPS WILL REMAIN MILD. ON SATURDAY...EXPECT THE FRONT TO BE HUNG UP OVER THE MTNS AT SUNRISE. UNLESS EXTENSIVE CONVECTIVE DEBRIS PREVENTS IT...CONVECTION SHOULD RE-FIRE EARLY IN THE DAY CLOSE TO THE FRONT AS IT DID TO OUR WEST THIS PAST MORNING. UPPER DIVERGENCE...DPVA...AND PLENTY OF MOISTURE SUGGEST ANOTHER POP IN THE LIKELY RANGE BY AFTERNOON OVER THE PIEDMONT...AND A CHANCE UP TO THE BLUE RIDGE. A GUIDANCE BLEND WAS USED FOR HIGH TEMPS. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... AT 200 PM EDT FRIDAY...12Z GFS AND NAM STILL SOMEWHAT AT ODDS AS TO HOW FAST THE FRONTAL BAND OF DEEP LAYER MOISTURE AND PRECIP WILL EXIT THE FORECAST AREA OVER THE EAST. THE NAM STIL IS FASTER AND HAS THE DEEP LAYER FRONTAL MOISTURE EAST OF THE AREA BY 00Z SUN...WHILE THE GFS IS CONSIDERABLY SLOWER AND WETTER. THE SREF APPEARS TO CONTINUE TO BE A GOOD COMPROMISE FOR THE SOLUTION. THE SREF KEEPS PRECIP CHANCES OVER THE EASTERN MOST PART OF THE FORECAST AREA EARLY ON SAT NIGHT...AND THEN MOVES THE MOISTURE/PRECIP EAST BY MIDNIGHT. WILL ALSO SCATTER AND CLEAR THE CLOUDS FROM NW TO SE SAT NIGHT. HIGH PRESSURE BUILDS OVER THE AREA ON SUN WHICH SHOULD PRODUCE A VERY NICE DAY WITH DEWPOINTS MIXING OUT INTO THE 50S OVER THE MOUNTAINS AND LOW 60S ELSEWHERE. THE HIGH SHIFTS EAST OF THE AREA ON MONDAY...BUT ITS LINGERING INFLUENCE SHOULD ALLOW FOR ANOTHER DRY DAY ON MONDAY. TEMPS ARE EXPECTED TO BE SLIGHTLY BELOW CLIMO ON SUN AND NEAR CLIMO ON MON. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... AT 130 PM EDT FRIDAY...A SOMEWHAT PROGRESSIVE PATTERN APPEARS TO BE IN STORE DURING THE MEDIUM RANGE. THE UPPER AIR PATTERN WILL GENERALLY FEATURE A MEAN TROUGH OVER THE EASTERN U.S. WITH INDICATIONS FROM THE LATEST 12Z GFS OF BUILDING HEIGHTS TOWARD THE END OF NEXT WEEK OVER THE EAST. LATEST HPC/GFS GUIDANCE SUGGESTS A WEAK COLD FRONT WILL CROSS THE REGION ON TUE ALONG WITH SCATTERED CONVECTION. THE GFS DRIVES THE FRONT SE OF THE AREA BY WED WITH HIGH PRESSURE BUILDING IN THROUGH THU. THUS ONLY CLIMO TYPE POPS FOR AFTERNOON CONVECTION IN THE MOUNTAINS WED AND THU. ANOTHER FRONT APPROACHES THE AREA ON FRI AND PER HPC WILL FORECAST CHANCE TYPE POPS. TEMPS SHOULD BE NEAR CLIMO THROUGH THE PERIOD. && .AVIATION /19Z FRIDAY THROUGH WEDNESDAY/... AT KCLT...SCATTERED SHOWERS DEVELOPING RAPIDLY OVER THE WRN PIEDMONT WHILE CLOUD BASES REMAIN MVFR. THIS SHOULD CONTINUE WITH A SLOW RISE IN THE LCL THROUGH EARLY AFTERNOON...SUCH THAT CONDITIONS SHOULD BECOME VFR BY 20Z. LOW CLOUDS WILL CONTINUE...HOWEVER...THROUGH THE REST OF THE DAYLIGHT HOURS GIVEN THE PLENTIFUL LOW LEVEL MOISTURE. THE LATEST GUIDANCE SUGGESTS THE BEST CHANCE FOR ANOTHER ROUND OF THUNDERSTORMS WILL BE EARLY THIS EVENING. THERE IS ENUF FORCING TO SUGGEST THAT STORMS ARE LIKELY...SO THE TARGET WINDOW OF 01Z TO 04Z HAS BEEN ESTABLISHED. SOME SHOWERS COULD CONTINUE OVERNIGHT WITH THE ACTUAL FRONT HUNG UP TO THE WEST. LOW CLOUDS SHOULD RETURN LATE TONIGHT...RESULTING IN AT LEAST AN MVFR CEILING AFTER 11Z. MORE LOW CLOUDS ARE POSSIBLE AGAIN SATURDAY MORNING WITH THE FRONT HUNG UP OVER THE MTNS. ELSEWHERE...LOW CLOUDS CONTINUE TO SCATTER OUT EARLY THIS EVENING... WHICH WILL FINALLY ALLOW FOR SOME DESTABILIZATION. SHOWERS WILL CONTINUE TO DEVELOP ACROSS THE MTNS THROUGH 22Z AND THEN PUSH EAST THROUGH THE EARLY EVENING. RETURN TO LOW MVFR/IFR CIGS TONIGHT AS FRONT SLOWS...IFR VSBY POSSIBLY MAINLY ACROSS KHKY AND KAVL WHERE DRY AIR ALOFT WORKS IN. OUTLOOK...A COLD FRONT WILL SLOWLY CROSS THE AREA LATE SATURDAY... WITH DRIER HIGH PRES BUILDING IN FROM THE W THE LATTER HALF OF THE WEEKEND. WEAK HIGH PRESSURE WILL LINGER THROUGH EARLY NEXT WEEK. AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)... WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...PM NEAR TERM...PM SHORT TERM...LG LONG TERM...LG AVIATION...PM
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
202 PM EDT FRI AUG 10 2012 .SYNOPSIS... A STRONG UPPER LEVEL TROUGH WILL CROSS OVER THE GREAT LAKES TODAY...AND PUSH A COLD FRONT ACROSS THE MID ATLANTIC. THIS FRONT WILL TRIGGER NUMEROUS SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND EVENING...WITH A FEW STORMS POSSIBLY BECOMING STRONG TO SEVERE. ONCE THE COLD FRONT DEPARTS LATER TONIGHT INTO SATURDAY...HIGH PRESSURE WILL ARRIVE TO PROVIDE COOLER AND DRIER CONDITIONS FOR THE REST OF THIS WEEKEND INTO EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1200 PM EDT FRIDAY... THE SHOWERS OVER WEST VIRGINIA ARE STILL PRESENT BUT GRADUALLY DECAYING. NEW DEVELOPMENT OF SHOWERS AND THUNDERSTORMS HAS BEEN DELAYED A FEW HOURS TOWARD THE MID AFTERNOON AND EVENING...AS INSTABILITY IS CURRENTLY STILL LACKING. THE THREAT FOR SEVERE WEATHER TODAY CONTINUES TO DIMINISH DUE TO CLOUD COVER REMAINING QUITE THICK OVER THE AREA...BUT SOME SUNSHINE IS PEEKING THROUGH ALONG THE BLUE RIDGE. MINOR TWEAKS WERE MADE TO THE POPS AND TEMPERATURES TO ACCOUNT FOR THE RECENT TRENDS ON RADAR AND SATELLITE. ALSO...WINDS WERE BUMPED UPWARD DUE TO ROANOKE AND DANVILLE BOTH OBSERVING A GUSTY SOUTHWEST WIND DEVELOPING...WHICH SHOULD CONTINUE THROUGH THE AFTERNOON. AS OF 1015 AM EDT FRIDAY... DUE TO THE DEPARTING BAND OF SHOWERS AND THUNDERSTORMS FROM LAST NIGHT...AND ANOTHER SMALL BAND OF SHOWERS CROSSING OVER SOUTHEAST WEST VIRGINIA AT THIS MOMENT...THERE WILL BE LOTS OF CLOUD COVER TO ERODE OVER THE AREA FOR ANY SIGNIFICANT RISK OF SEVERE WEATHER. THE SMALL BAND OF SHOWERS OVER WEST VIRGINIA WILL GRADUALLY DISSIPATE AS IT CROSSES THE BLUE RIDGE IN A FEW HOURS. RECOVERING THE INSTABILITY WILL BE THE KEY FOR TODAY. LAPSE RATES IN THE 12Z RNK SOUNDING ARE NOT IMPRESSIVE...BUT WITH ENOUGH DAYTIME HEATING AND DYNAMICAL SUPPORT AS THE SURFACE COLD FRONT DRAWS CLOSER...THERE SHOULD BE SUFFICIENT SUPPORT FOR THE GROWTH OF NUMEROUS SHOWERS AND THUNDERSTORMS LATER THIS AFTERNOON. IF ANY OF THESE STORMS BECOME STRONG TO SEVERE...DAMAGING WINDS AND HEAVY RAIN WILL BE THE PRIMARY THREATS. SINCE CLOUD COVER AND BANDS OF CONVECTION WILL BE ONGOING THROUGHOUT THE DAY...THE TEMPERATURE FORECAST IS QUITE PROBLEMATIC. AT THIS TIME...TEMPERATURES WERE BUMPED UPWARD FOR HIGHS WEST OF THE BLUE RIDGE DUE TO SOME BREAKS IN THE CLOUDS. OTHER AREAS WERE KEPT CLOSE TO THE PREVIOUS FORECAST AND MOS GUIDANCE...WITH HIGHS IN THE MID TO UPPER 70S WEST OF THE BLUE RIDGE...AND LOWER TO MID 80S IN THE PIEDMONT. WITH REGARDS TO POPS...A SMALL AREA OF LIKELY CHANCES WERE UTILIZED TO ACCOUNT FOR THE DECAYING BAND OF SHOWERS OVER WEST VIRGINIA THIS MORNING. LIKELY POPS WEST OF THE BLUE RIDGE...AND CATEGORICAL POPS OVER THE PIEDMONT WERE PLACED THIS AFTERNOON AND EVENING...AS THERE SHOULD BE BANDED CONVECTION FORMING ALONG AND WEST OF THE BLUE RIDGE...AND BECOMING MORE ORGANIZED AS IT HEADS EASTWARD. AS OF 315 AM EDT FRIDAY... MAIN CONCERN TODAY WITH THE DEGREE OF POSSIBLE RENEWED CONVECTION LATER ON AS THE UPPER LOW TO THE NW PROPELS A STRONG COLD FRONT TO ALONG THE WESTERN SLOPES THIS EVENING AND EAST OF THE BLUE RIDGE OVERNIGHT. AGAIN ONE OF THE MAIN FACTORS IS WITH JUST HOW MUCH DEEP INSTABILITY CAN BE GENERATED THIS AFTERNOON IN THE WAKE OF THE CURRENT MVC THAT WILL EXIT THE CWA BY DAYBREAK. THIS FEATURE AND ITS CONVECTION HAVE BASICALLY REMOVED ANY LINGERING CAPE FROM THU EVENING AND WILL NEED A PERIOD OF STRONG HEATING TO REGENERATE ENOUGH INSTABILITY FOR A MORE WIDESPREAD SEVERE THREAT. LATEST FCST SOUNDINGS DO SHOW WIND FIELDS STRENGTHENING/BACKING ALOFT AHEAD OF THE UPSTREAM TROF THRU THIS EVENING SUGGESTING POTENTIAL FOR BANDS OF DEEPER CONVECTION THAT MAY EVENTUALLY LINE UP ESPCLY OUT EAST BY THIS EVENING. HOWEVER LATEST MODELS REMAIN SPREAD ACROSS THE BOARD WITH TIMING AND LOCATION ISSUES OF PRE- FRONTAL LIFT PER SLOWNESS IN INITIALIZING WITH THE CURRENT REMNANT MCS ATTM. APPEARS BEST SOLUTION IS TO LEAN TOWARD THE LATEST HRRR AND GO WITH DEVELOPMENT OF MULTICELLULAR BANDS OVER THE MOUNTAINS BY EARLY AFTERNOON PER UNIDIRECTIONAL FLOW AND THETA-E RIDGING...WITH THIS COVERAGE OR ANOTHER LINE GRADUALLY ORGANIZING UPON HEADING EAST INTO BETTER INSTABILITY OUT EAST THRU EARLY EVENING. THIS AGAIN BASED ON AT LEAST SOME HEATING AS SUGGESTED BY THE LATEST NAM WHICH BREAKS OPEN THE MID DECK LATER THIS MORNING AHEAD OF THE BOUNDARY. THUS HAVE ADJUSTED POPS TO REFLECT A BREAK IN COVERAGE PER WEAK SUBSIDENCE IN BEHIND THE PASSING VORT EARLY THIS MORNING...INCREASING TO LIKELY/CAT POPS WEST EARLY/MID AFTERNOON...THEN TRANSLATING EAST INTO EARLY THIS EVENING. THINK COVERAGE MOVING ENOUGH TO PRECLUDE A FLASH FLOOD WATCH BUT CERTAINLY A WIND THREAT GIVEN DECENT FCST DCAPES WHICH WILL COVER IN THE HWO PER SWODY1 SLIGHT RISK. WILL STAY ON THE WARM SIDE OF MOS TEMPS TODAY AS THINKING SOME INSOLATION BUT IF CLOUDS HOLD AND CONVECTION FASTER THEN HIGH BUST POTENTIAL REMAINS. EXPECT MAIN AXIS OF CONVECTION TO BE EAST OF THE MOUNTAINS THIS EVENING AND MAY TAKE SOME TIME TO EXIT THE PIEDMONT AS ANOTHER WEAK IMPULSE RIDES UP THE FRONT. THINK SEVERE POTENTIAL LIMITED BEHIND THE INIT WAVE OF STORMS BUT LINGERING HEAVY RAIN THREAT COULD PERSIST WHILE SHOWERS BECOME WIDELY SCATTERED OR END BEHIND THE BOUNDARY OVER THE MOUNTAINS OVERNIGHT. THEREFORE DID DECREASE POPS A BIT FASTER WEST THINKING CONVECTION WILL HELP TAKE DEEP MOISTURE TO THE EAST LATE...BUT LIKELY STILL LOTS OF CLOUDS AS THE UPPER FLOW REMAINS SW AND PARALLEL TO THE SFC FRONT. MAIN PUSH OF 85H COOL ADVECTION WILL STILL BE WEST OF THE BLUE RIDGE LATE TONIGHT SO KEEPING TEMPS WARMER OUT EAST AND NOT QUITE AS COOL MOUNTAINS PER CLOUD COVER. OTRW RANGE OF LOWS FROM AROUND 60 FAR WEST TO 65-70 SE LOOKS BEST. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 300 AM EDT FRIDAY... SHORTWAVE PIVOTS ACROSS THE CENTRAL APPALACHIANS SATURDAY AFTERNOON. THIS WILL KEEP THE THREAT OF SHOWERS AND ISOLATED THUNDERSTORMS GOING IN THE EAST WITH COOL POOL ALOFT. 8H TEMPS COOL TO +14C...SO WITH SOME CLOUD COVER FROM THE COLDER AIR ALOFT...EXPECT HIGHS CLOSE TO THE ADJMETBC WITH READINGS FROM THE MID 70S IN THE MOUNTAINS TO THE MID 80S IN THE SOUTHEAST. DRIER AIR WILL FINALLY WORKS IN FROM THE NORTHWEST SATURDAY NIGHT INTO SUNDAY WITH DEWPOINTS DROPPING INTO THE UPPER 40S/LOWER 50S IN THE HIGHER ELEVATIONS WITH MID 50S VALLEYS. THE PIEDMONT COULD SEE SOME 50S DEWPOINTS BUT HARD TO DISPLACE THE HUMID AIRMASS ACROSS THE CAROLINAS AS THE FLOW ALOFT STAYS WSW. PLAYED LOW TEMPERATURES SATURDAY NIGHT FROM THE LOWER 50S IN THE MOUNTAINS TO THE LOWER 60S IN THE EAST. ON SUNDAY...TEMPERATURES MODERATE WITH WSW FLOW AND MORE SUNSHINE. HEIGHTS/8H TEMPERATURES INCREASE AGAIN...HIGHS SUNDAY RETURNING TO AROUND 80 DEGREES IN THE MOUNTAINS TO THE UPPER 80S IN THE SOUTHEAST. LEANED TOWARDS THE ECMWFBC FOR SUNDAY NIGHT LOW TEMPERATURES WITH VALUES FROM THE MID 50S IN THE WEST TO THE MID 60S IN THE EAST. && .LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 400 PM EDT THURSDAY... DRIER AIRMASS WILL BE DISPLACED DURING THIS PERIOD AS THE FRONT FROM THE SHORT TERM PERIOD STALLS ACROSS THE CAROLINAS/TN VALLEY THEN SHIFTS SLOWLY NORTH BY TUESDAY AS ANOTHER WAVE OF LOW PRESSURE SHIFTS ACROSS IT FROM THE LOWER MISSOURI VALLEY INTO THE VA TIDEWATER FROM MON-TUE. THIS FRONT WILL BE CLOSE ENOUGH THAT SHOWER/TSRA CHANCES INCREASE AGAIN BY TUESDAY. ONCE THE SHORTWAVE/ASSOCIATED SFC LOW PASS TUESDAY AFTERNOON...WEAK HIGH PRESSURE WILL PUSH THE FRONT BACK SOUTH INTO THE GA/SC BY WEDNESDAY AND THE AIRMASS DRIES OUT SOME...BUT THE UPPER TROUGH IS NOT AS DEEP AS THIS WEEKENDS. OVERALL...THE TEMPS NEXT WEEK WILL AVERAGE 80S/LOWER 90S FOR HIGHS AND 60S FOR LOWS. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... AS OF 200 PM EDT FRIDAY... CEILINGS HAVE LIFTED BACK UP TO VFR THIS AFTERNOON...WITH THE EXCEPTION OF MVFR CEILINGS STILL PERSISTING IN BLF. BROKEN LINES OF SHOWERS AND THUNDERSTORMS ARE DEVELOPING OVER KENTUCKY AND TENNESSEE...AND ARE EXPECTED TO CONTINUE MOVING EASTWARD ALONG THE ADVANCING SURFACE FRONT. A FEW SHOWERS ARE ALSO POPPING UP OVER WEST VIRGINIA AHEAD OF THE FRONT. THUS...THUNDERSTORMS WERE KEPT IN ALL THE TAFS. THE TIMING OF THE CONVECTION HAS SLOWED DOWN SEVERAL HOURS FROM THE PREVIOUS FORECAST. THE TIME RANGE BETWEEN 20Z AND 03Z NOW SEEMS MOST FAVORABLE FOR THUNDERSTORMS. ONCE THE PRECIPITATION SUBSIDES TONIGHT...THE MOIST GROUND WILL PROVIDE THE POTENTIAL FOR SOME MVFR FOG IN BLF AND BCB. LWB IS MOST LIKELY TO DROP TO LIFR WHEN THE WINDS TURN CALM OVERNIGHT. MEANWHILE...TOO MUCH LOW CLOUD COVER WILL IMPEDE FURTHER FOG DEVELOPMENT TO THE EAST. BY SATURDAY MORNING...A DRIER AIR MASS BEHIND THE FRONT WILL MOVE INTO THE AREA...AND PROMPT A RETURN TO VFR CONDITIONS. HIGH PRESSURE WILL PROVIDE GOOD FLYING WEATHER THROUGH THE REMAINDER OF THIS WEEKEND INTO EARLY NEXT WEEK. ANOTHER DISTURBANCE WILL PROVIDE THE NEXT CHANCE OF ISOLATED SHOWERS AND THUNDERSTORMS BY TUESDAY AND WEDNESDAY. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...PW NEAR TERM...JH/PW SHORT TERM...KK LONG TERM...WP AVIATION...PW