Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 09/26/13


AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
740 PM EDT WED SEP 25 2013 .UPDATE (TONIGHT AND THURSDAY)... BELIEVE IT OR NOT...THE SUN ACTUALLY CAME OUT FOR A BRIEF TIME AT THE NWS OFFICE IN RUSKIN THIS EVENING. A WELCOME CHANGE AFTER THE PAST SEVERAL DAYS. ADJUSTED RAIN CHANCES FOR CURRENT CONDITIONS AND LATEST GUIDANCE ENSEMBLE FOR THE REST OF TONIGHT AND THURSDAY...AND ADDED AN EXERCISE CAUTION HEADLINE TO MOST OF THE MARINE AREA THROUGH THE REMAINDER OF THE EVENING. 23Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS AND AMPLIFIED AND COMPLEX UPPER LEVEL PATTERN IN PLACE OVER THE CONUS. AN ENERGETIC LONGWAVE TROUGH COVERS MUCH OF THE INTER-MOUNTAIN WEST BEFORE THE FLOW RIDGES UP OVER THE MID-SECTION OF THE COUNTRY/UPPER MIDWEST. SOUTHERN BRANCH OF DOWNSTREAM SPLIT FLOW THEN CARVES OUT A BROAD TOUGH INTO THE SOUTHEASTERN STATES. WV IMAGERY SHOWS A BROAD EXPANSE OF SUBSIDENCE AND MID/UPPER LEVEL DRY AIR PUSHING EAST AND SOUTHEAST TOWARD THE REGION ON THE BACKSIDE OF THE TROUGH. STILL SEEING A PLUME OF DEEPER MOISTURE OVER THE FL PENINSULA THIS EVENING...HOWEVER GUIDANCE ENSEMBLES ARE IN AGREEMENT THAT THIS DRIER AIR TO OUR NORTH AND WEST WILL BEGIN TO MAKE PROGRESS OVER THE FL PENINSULA DURING THE NEXT 18 - 24 HOURS. AT THE SURFACE...A STALLED FRONTAL BOUNDARY REMAINS NEAR THE I-10 CORRIDOR AND IS PROVIDING THE FOCUS FOR A THIN LINE OF SHOWERS/STORMS MOVING CLOSE TO THE NORTHERN PORTIONS OF LEVY COUNTY. ELSEWHERE...SEEING A GENERALLY DRY EVENING TAKING SHAPE WITH THE EXCEPTION OF A FEW LIGHTER SHOWERS DOWN TOWARD CHARLOTTE/LEE COUNTIES. EVEN FOR THESE FAR SOUTHERN COUNTIES...NOT MUCH IN THE WAY OF MEASURABLE RAINFALL IS EXPECTED THROUGH THE NEXT SEVERAL HOURS AT LEAST. THE APPROACH OF ONE FINAL IMPULSE AND A BROAD/WEAK AREA OF SYNOPTIC SUPPORT MOVING AROUND THE BASE OF THE TROUGH LATER TONIGHT MAY SUPPORT A SCATTERING OF SHOWERS DEVELOPING OVER THE COASTAL WATERS AND PUSHING TOWARD THE COASTAL ZONES. WILL KEEP A 30-40% CHANCE OF SHOWERS IN THE FORECAST LATER TONIGHT FOR THE COAST AND I-75 CORRIDOR...WITH LESSER 20% CHANCES INLAND. HOWEVER...ANY RAIN THAT DOES OCCUR OVERNIGHT WILL BE SPOTTY AND GENERALLY LIGHT DUE TO THE DECREASING COLUMN MOISTURE AND WEAKER DYNAMICS...AS OPPOSED TO THE WIDESPREAD AND HEAVY BANDS EXPERIENCED DURING THE PAST SEVERAL DAYS. THE DRIER AIR WILL CONTINUE ITS MARCH SOUTHWARD DURING THE DAYLIGHT HOURS OF THURSDAY...REPLACING THE DEEP TROPICAL MOISTURE. BEST CHANCES FOR SCATTERED SHOWERS DURING TUESDAY MORNING WILL BE FROM THE I-4 CORRIDOR SOUTHWARD...BUT THIS AREA SHOULD SHRINK EVEN FURTHER SOUTHWARD BY THE SECOND HALF OF THE DAY. ONCE AGAIN...ANY RAINFALL THAT DOES OCCUR SHOULD BE SCATTERED IN NATURE...AND NOT AMOUNT TO MUCH IN TERMS OF ACCUMULATION. THE WORST OF THE RAINFALL FROM THIS EVENT CERTAINLY APPEARS TO BE OVER...AND WE CAN LOOK FORWARD TO SOME BRIGHTER AND DRIER DAYS AHEAD. && .AVIATION... SHRA HAVE ENDED AS A WEAK SURFACE TROUGH BEGINS TO SLIDE SOUTH WITH SOME DRIER AIR BEHIND IT. HOWEVER THERE WILL STILL BE ENOUGH MOISTURE FOR LATE NIGHT/EARLY MORNING MVFR CIGS. TPA/PIE/LAL COULD SEE AN ISOLD SHRA AROUND SUNRISE. PGD/FMY/RSW MAY HAVE A SCT TSRA IN THE AFTERNOON. SW WINDS BECOME WEST THEN NW DURING THU. && .MARINE... A LOCALLY TIGHT GRADIENT ACROSS THE EASTERN GULF IS PROVIDING FOR CAUTIONARY LEVEL WIND CONDITIONS THIS EVENING. HAVE ADDED A EXERCISE CAUTION HEADLINE TO ALL MARINE ZONES WITH THE EXCEPTION OF TAMPA BAY...ALTHOUGH WINDS MAY AT TIMES APPROACH CAUTIONARY LEVELS NEAR THE SKYWAY. THESE ROUGHER CONDITIONS WILL CONTINUE THROUGH AT LEAST THE NEXT SEVERAL HOURS...BUT THEN BEGIN TO SUBSIDE LATER TONIGHT AND ESPECIALLY DURING THURSDAY MORNING. WINDS WILL VEER MORE TO THE NORTHWEST DURING THURSDAY...AND THEN TO THE NORTH AND NORTHEAST THURSDAY NIGHT AND FRIDAY. && .HYDROLOGY... RAINFALL AMOUNTS RANGING FROM 5 TO 8 INCHES SINCE MONDAY HAS CAUSED RIVERS IN PASCO COUNTY SOUTHWARD TO SARASOTA AND CHARLOTTE COUNTIES TO RISE ABOVE FLOOD STAGE. RAIN CHANCES WILL DECREASE OVER THE NEXT FEW DAYS...HOWEVER IT WILL TAKE SEVERAL DAYS FOR THE WATER LEVELS TO FALL BELOW FLOOD STAGE. CHECK THE RIVERS SECTION ON OUR WEBSITE FOR THE LATEST INFO. && .PRELIMINARY POINT TEMPS/POPS... TPA 77 88 74 88 / 40 30 10 10 FMY 76 90 75 91 / 40 40 20 20 GIF 74 90 70 87 / 20 30 10 10 SRQ 79 89 75 89 / 40 30 10 10 BKV 73 90 68 88 / 30 20 10 10 SPG 79 88 77 88 / 40 30 10 10 && .TBW WATCHES/WARNINGS/ADVISORIES... FL...RIP CURRENT RISK THROUGH THURSDAY EVENING FOR CHARLOTTE- HILLSBOROUGH-LEE-MANATEE-PINELLAS-SARASOTA. GULF WATERS...NONE. && $$ UPDATE/MARINE...MROCZKA AVIATION...RUDE HYDROLOGY...WYNN
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1007 PM CDT WED SEP 25 2013 .DISCUSSION... 849 PM CDT NO MAJOR CHANGES MADE TO THE GOING FORECAST WITH TWEAKS TO HOURLY TRENDS THE ONLY ADJUSTMENTS NEEDED. WINDS WILL CONTINUE TO EASE AND BECOME LIGHT AND VARIABLE WITH A TREND TOWARDS EAST-SOUTHEAST OVERNIGHT. WILL CONTINUE WITH PATCHY FOG MENTION...WITH THE GREATEST LIKELIHOOD IN LOW LYING AREAS. OVERALL EXPECT CONDITIONS SIMILAR TO LAST NIGHT. MDB //PREV DISCUSSION... 253 PM CDT STRETCH OF QUIET WEATHER WILL ROUND OUT THE REMAINDER OF THE WEEK...THEN A BRIEF WINDOW OF SHOWERS AND POSSIBLY THUNDERSTORMS WILL IMPACT THE REGION AS A COLD FRONT SWEEPS ACROSS THE AREA LATE SATURDAY AND SATURDAY NIGHT. REST OF TODAY AND TONIGHT... HIGH PRESSURE REMAINS IN CONTROL THIS AFTERNOON CENTERED OVER THE NORTHERN GREAT LAKES REGION WITH RIDGING EXTENDING SOUTHWEST INTO THE MID MISSOURI VALLEY. ALOFT...A 110KT JET MAX IS ANALYZED OVER THE INTERMOUNTAIN WEST...ROUNDING THE BASE OF A LONGWAVE TROUGH WHICH IS CENTERED OVER THE PACIFIC NORTHWEST REGION. FLAT RIDGING IS IN PLACE FARTHER EAST ACROSS THE MISSISSIPPI VALLEY. A CHANNEL OF DRIER MIDLEVEL AIR IS NOTED ON WATER VAPOR IMAGERY...ADVECTING OVERHEAD IN THE WAKE A CLOSED UPPER LOW MOVING EAST ACROSS THE MID APPALACHIAN RANGE. THIS AREA OF SUBSIDENCE AND DRIER AIR HAS HELPED TO KEEP SKIES MOSTLY SUNNY THIS AFTERNOON...AND WILL KEEP SKIES CLEAR OVERNIGHT. TEMPERATURES SHOULD ONCE AGAIN RADIATE WELL NEAR THE RIDGE AXIS...AND MAY SEE SOME FOG DEVELOPMENT... PARTICULARLY IN LOW LYING AREAS OR TYPICAL FOG PRONE AREAS. THURSDAY AND FRIDAY... AFOREMENTIONED JET STREAK OVER THE INTERMOUNTAIN WEST WILL LIFT NORTHEAST ACROSS THE PLAINS STATES THURSDAY AND FRIDAY WITH THE LONGWAVE RIDGE AMPLIFYING OVER THE MISSISSIPPI VALLEY. AT THE SURFACE...LOW PRESSURE WILL DEEPEN AS IT LIFTS FROM THE NORTHERN PLAINS THURSDAY INTO THE CANADIAN PRAIRIES ON FRIDAY WITH SOUTHERLY FLOW INCREASING LOCALLY. H85 TEMPS AROUND 12C TODAY WILL WARM TO AROUND 15C THURSDAY AFTERNOON...AND 16C FRIDAY AFTERNOON. LATE SEPTEMBER AND EARLY OCTOBER UPPER AIR CLIMATOLOGY INDICATES MEAN TEMPERATURES IN THE LOW TO MID 80S GIVEN THE UPPER AIR PROFILE...WHICH IS ABOVE ALL GUIDANCE. EVEN THE GEM AND ECMWF WHICH TEND TO PERFORM WELL WITH TEMPERATURES UNDER A THERMAL RIDGE WERE SEVERAL DEGREES COOLER. BLENDED TOWARDS THE GEMNH WHICH WAS AMONGST THE WARMEST GUIDANCE AND THEN TRENDED UP SLIGHTLY FROM THERE. WITH DRY ANTECEDENT CONDITIONS...LITTLE SIGNAL FOR CLOUD COVER OUTSIDE OF AM FOG...SEE LITTLE REASON TO BE SO FAR ON THE COOL SIDE OF THE CLIMATOLOGICAL MEAN. THE ONLY EXCEPTION WILL BE ALONG THE LAKE SHORE IN ILLINOIS WHERE TEMPERATURES WILL STAY COOLER WITH ONSHORE FLOW. SATURDAY AND SUNDAY... UPPER AIR PATTERN BEGINS TO BUCKLE AS THE WEST COAST TROUGH LIFTS ENE ACROSS THE UPPER MIDWEST ON SATURDAY. A STRONG RESPONSE IS NOTED AT THE SURFACE PER GFS AND VERY END OF THE NAM RUN AS LOW PRESSURE DEEPENS FROM AROUND 1000 MB FRIDAY NIGHT OVER THE UPPER MIDWEST...TO AROUND 980 MB LATE SATURDAY NIGHT AS IT MOVES OVER HUDSON BAY. THE ECMWF INDICATES A LESS ORGANIZED/DEEP LOW DEVELOPING...WITH A SLIGHTLY MORE SOUTHERLY TRACK. EITHER WAY...STRONGEST PRESSURE FALLS OCCUR WELL NORTH OF THE LOCAL CWA...BUT STILL EXPECT BREEZY SOUTHERLY WINDS SATURDAY WITH GUSTS AROUND 30 MPH POSSIBLE...MAYBE EVEN STRONGER IF THE NCEP GUIDANCE IS ON THE RIGHT TRACK WITH THE DEEPER LOW. MODELS CONTINUE TO HONE IN ON TIMING FRONTAL PASSAGE AND ARE IN DECENT AGREEMENT SHOWING THE FRONT ENTERING THE NORTHWEST CWA SATURDAY EVENING...EXITING THE EASTERN CWA EARLY SUNDAY MORNING. FORECAST SOUNDINGS INDICATE PRETTY POOR MIDLEVEL LAPSE RATES AND LITTLE IF ANY INSTABILITY ALONG AND JUST AHEAD OF THE FRONT...SO EXPECT THE THUNDER THREAT TO BE PRETTY LOW WITH THIS SYSTEM...BUT MOST AREAS SHOULD SEE RAIN WITH THE FRONT. MONDAY THROUGH WEDNESDAY... PATTERN APPEARS ZONAL AND PROGRESSIVE THROUGH NEXT WEEK. HIGH PRESSURE WILL BUILD EAST ACROSS THE CWA MONDAY WITH RETURN FLOW TUESDAY ALLOWING TEMPERATURES TO RETURN TO ABOVE NORMAL CONDITIONS. MODELS IN AGREEMENT THAT ANOTHER FRONT WILL SWEEP ACROSS THE REGION MIDWEEK...THOUGH TIMING AND STRENGTH OF THE SYSTEM THIS FAR OUT IS STILL QUESTIONABLE. DEUBELBEISS && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 03Z... * NONE. MDB //DISCUSSION...UPDATED 00Z... HIGH PRESSURE REMAINS CENTERED OVER EASTERN CANADA WITH NORTHEAST WINDS BEGINNING TO DIMINISH NOW THAT SUNSET IS APPROACHING. WILL MONITOR FOR POSSIBLE FOG DEVELOPMENT OVERNIGHT BUT EXPECT CONDITIONS SIMILAR TO LAST NIGHT WITH SOME MVFR VSBY DEVELOPING AT RFD/DPA. WINDS WILL TURN EAST-SOUTHEAST TO SOUTHEAST AND INCREASE TO NEAR 10 KT THURSDAY MORNING. THE LAKE MAY HELP TO TURN WINDS A BIT MORE EASTERLY AT ORD/MDW BY MID AFTERNOON AND GYY MAY SEE AN EAST-NORTHEAST DIRECTION DEVELOP. WINDS WILL THEN DIMINISH WITH SUNSET AND TREND BACK SOUTHEAST LATER THURSDAY EVENING. ANY MORNING VSBY REDUCTION WILL DISSIPATE LEAVING VFR CONDITIONS. MDB //ORD AND MDW CONFIDENCE...UPDATED 03Z... * HIGH CONFIDENCE ALL ELEMENTS. MDB //OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z... FRIDAY...DRY/VFR. SATURDAY...GUSTY SOUTHERLY WINDS POSSIBLE. CHANCE OF SHRA/TSRA LATE AFTERNOON...LIKELY SATURDAY NIGHT. SUNDAY THROUGH TUESDAY...DRY/VFR. MDB && .MARINE... 302 PM CDT A PERSISTENT LARGE AREA OF HIGH PRESSURE CENTERED OVER THE NORTHERN GREAT LAKES WILL BEGIN TO SLOWLY MOVE EAST THURSDAY AND FRIDAY AS IT STRENGTHENS A BIT MORE. LOW PRESSURE DEVELOPING OVER THE CENTRAL ROCKIES IS EXPECTED TO MOVE OUT INTO THE NORTHERN PLAINS THURSDAY AND CONTINUE INTO MANITOBA THURSDAY NIGHT AND FRIDAY. ANOTHER LOW WILL DEVELOP OVER THE CENTRAL PLAINS THURSDAY NIGHT. THIS LOW WILL THEN ELONGATE INTO A TROUGH OF LOW PRESSURE WITH AN ASSOCIATED COLD FRONT EXTENDING FROM MINNESOTA SOUTHWEST INTO COLORADO. THIS SYSTEM WILL SLOWLY TRACK ACROSS THE PLAINS FRIDAY AND SATURDAY...WITH THE COLD FRONT MOVING ACROSS THE LAKE SATURDAY NIGHT. KREIN && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
  [top] Area Forecast Discussion National Weather Service Lincoln IL 908 PM CDT Wed Sep 25 2013 .DISCUSSION... ISSUED 900 PM CDT Wed Sep 25 2013 Mostly clear skies and light E-NE winds will provide favorable radiational cooling conditions tonight. Fog potential will be higher south of I-70, but we can not rule out some light ground fog forming north of there as well. We are not expecting the fog to significantly affect travel, with vis reduction down to maybe 3-4 miles at the lowest point toward sunrise tomorrow. We will continue to mention fog in the south and monitor dewpoint depressions across the north where they currently are 10-15F. Forecast lows are projected to end up close to the 02z/9pm dewpoints, so fog potential is there. Low temps appear reasonable based on dewpoints this afternoon during peak mixing, so no big changes were needed there. Besides a few cumulus clouds tomorrow around 5k ft, another pleasant day is in store for Thursday. Sky grids look good, as do the remainder of the grids over the next 12-24 hrs. No formal update will be needed this evening. Shimon && .AVIATION... ISSUED 637 PM CDT Wed Sep 25 2013 High surface pressure will build into Illinois tonight and tomorrow as a weak low departs toward the East Coast. Ridging aloft will occur over the next 24 hours, helping to provide mostly clear skies through this taf period. The main concern will be some patchy ground fog that may bring mvfr vis to the terminal sites between 11z and 14z. A 3 hour tempo group was added to all tafs for that time period. Upstream dewpoints are in the mid 40s to the northeast, but airmass changes will slow tonight, leaving slightly higher dewpoints in central Illinois. That will set the stage for some fog to develop as favorable radiational cooling conditions allow air temps to drop close to the dewpoint late tonight. Forecast soundings from the NAM and RUC show a shallow low level saturation, lending some confidence in at least a tempo group for mvfr vis. Winds will start our light northeast, then become southeast tomorrow as the ridge axis passes east of Illinois and influences from low pressure in the plains affect the sfc wind pattern. Shimon && .PREV DISCUSSION... ISSUED 308 PM CDT Wed Sep 25 2013 A progressive and high amplitude upper level pattern will give way to more of a semi-zonal flow by late in the weekend into early next week. This pattern will result in temperatures above normal for the rest of the week. Our next chance for much needed rainfall is expected as the pattern transitions to more of a zonal flow due to an upper trough quickly lifts across the upper Midwest later Saturday. From about Tuesday and beyond, the medium range models diverge significantly in their upper level patterns and associated temperature fields. SHORT TERM...Tonight through Friday night Some lingering low level moisture, a light easterly flow and a more extensive cu field in southeast IL this afternoon will set the stage for patchy fog mainly south of I-70 overnight. Forecast NAM soundings indicate a stronger inversion and a bit more low level moisture and fog in southeast IL as opposed to central IL, where only a few spots of very shallow ground fog are possible. From Thursday through Friday, high pressure centered in Quebec will have ridging extend back into the Midwest. Aloft, upper level ridging/heights will build, allowing warm conditions to return. The result of this will be a mostly sunny sky with above normal temperatures in the lower to middle 80s. LONG TERM...Saturday through Wednesday The models are in pretty good agreement regarding the timing of an ejecting trough from the southwest U.S. and its associated cold front. It still appears that the vast majority of the rain will be along and behind the cold front. The NAM is the quickest model with the advancing rain chances, with the GFS, Canadian and European a bit slower. Prefer the slightly slow solutions with the rain along and west of the IL River valley later Saturday afternoon, and moving into the rest of central and eastern IL Saturday evening. The models also agree the rain is not expected to persist very long, with areas west of I-57 ending by daybreak Sunday, and then ending in eastern IL Sunday morning. Instability is expected to be quite limited with this system, so the best chances for thunderstorms will be in west central IL Sat afternoon, with more isolated thunderstorms Sat night and early Sunday. A brief cool down toward more normal temperatures for late September is anticipated behind the cold front Sunday and Monday as high pressure covers the Midwest. By Tuesday though, the European and GFS have very different ideas about our upper level pattern and low level temperature fields. The GFS has more of a light semi-zonal flow aloft with cooler temperatures, while the European tries to build an upper level ridge as it depicts a more vigorous trough digging into the southwestern states. The GFS is showing more run to run consistency with its solution, while the European 12z run is the first one to show these warmer temperatures and stronger ridging in the Midwest. Thus, will be more conservative with temperatures for Tuesday and Wednesday, but still go a few degrees above normal. Neither model is indicating much of a potential for precipitation Monday through Wednesday in central or southeast IL, so will keep the forecast dry for that period. Miller && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
654 PM CDT WED SEP 25 2013 .DISCUSSION... 253 PM CDT STRETCH OF QUIET WEATHER WILL ROUND OUT THE REMAINDER OF THE WEEK...THEN A BRIEF WINDOW OF SHOWERS AND POSSIBLY THUNDERSTORMS WILL IMPACT THE REGION AS A COLD FRONT SWEEPS ACROSS THE AREA LATE SATURDAY AND SATURDAY NIGHT. REST OF TODAY AND TONIGHT... HIGH PRESSURE REMAINS IN CONTROL THIS AFTERNOON CENTERED OVER THE NORTHERN GREAT LAKES REGION WITH RIDGING EXTENDING SOUTHWEST INTO THE MID MISSOURI VALLEY. ALOFT...A 110KT JET MAX IS ANALYZED OVER THE INTERMOUNTAIN WEST...ROUNDING THE BASE OF A LONGWAVE TROUGH WHICH IS CENTERED OVER THE PACIFIC NORTHWEST REGION. FLAT RIDGING IS IN PLACE FARTHER EAST ACROSS THE MISSISSIPPI VALLEY. A CHANNEL OF DRIER MIDLEVEL AIR IS NOTED ON WATER VAPOR IMAGERY...ADVECTING OVERHEAD IN THE WAKE A CLOSED UPPER LOW MOVING EAST ACROSS THE MID APPALACHIAN RANGE. THIS AREA OF SUBSIDENCE AND DRIER AIR HAS HELPED TO KEEP SKIES MOSTLY SUNNY THIS AFTERNOON...AND WILL KEEP SKIES CLEAR OVERNIGHT. TEMPERATURES SHOULD ONCE AGAIN RADIATE WELL NEAR THE RIDGE AXIS...AND MAY SEE SOME FOG DEVELOPMENT... PARTICULARLY IN LOW LYING AREAS OR TYPICAL FOG PRONE AREAS. THURSDAY AND FRIDAY... AFOREMENTIONED JET STREAK OVER THE INTERMOUNTAIN WEST WILL LIFT NORTHEAST ACROSS THE PLAINS STATES THURSDAY AND FRIDAY WITH THE LONGWAVE RIDGE AMPLIFYING OVER THE MISSISSIPPI VALLEY. AT THE SURFACE...LOW PRESSURE WILL DEEPEN AS IT LIFTS FROM THE NORTHERN PLAINS THURSDAY INTO THE CANADIAN PRAIRIES ON FRIDAY WITH SOUTHERLY FLOW INCREASING LOCALLY. H85 TEMPS AROUND 12C TODAY WILL WARM TO AROUND 15C THURSDAY AFTERNOON...AND 16C FRIDAY AFTERNOON. LATE SEPTEMBER AND EARLY OCTOBER UPPER AIR CLIMATOLOGY INDICATES MEAN TEMPERATURES IN THE LOW TO MID 80S GIVEN THE UPPER AIR PROFILE...WHICH IS ABOVE ALL GUIDANCE. EVEN THE GEM AND ECMWF WHICH TEND TO PERFORM WELL WITH TEMPERATURES UNDER A THERMAL RIDGE WERE SEVERAL DEGREES COOLER. BLENDED TOWARDS THE GEMNH WHICH WAS AMONGST THE WARMEST GUIDANCE AND THEN TRENDED UP SLIGHTLY FROM THERE. WITH DRY ANTECEDENT CONDITIONS...LITTLE SIGNAL FOR CLOUD COVER OUTSIDE OF AM FOG...SEE LITTLE REASON TO BE SO FAR ON THE COOL SIDE OF THE CLIMATOLOGICAL MEAN. THE ONLY EXCEPTION WILL BE ALONG THE LAKE SHORE IN ILLINOIS WHERE TEMPERATURES WILL STAY COOLER WITH ONSHORE FLOW. SATURDAY AND SUNDAY... UPPER AIR PATTERN BEGINS TO BUCKLE AS THE WEST COAST TROUGH LIFTS ENE ACROSS THE UPPER MIDWEST ON SATURDAY. A STRONG RESPONSE IS NOTED AT THE SURFACE PER GFS AND VERY END OF THE NAM RUN AS LOW PRESSURE DEEPENS FROM AROUND 1000 MB FRIDAY NIGHT OVER THE UPPER MIDWEST...TO AROUND 980 MB LATE SATURDAY NIGHT AS IT MOVES OVER HUDSON BAY. THE ECMWF INDICATES A LESS ORGANIZED/DEEP LOW DEVELOPING...WITH A SLIGHTLY MORE SOUTHERLY TRACK. EITHER WAY...STRONGEST PRESSURE FALLS OCCUR WELL NORTH OF THE LOCAL CWA...BUT STILL EXPECT BREEZY SOUTHERLY WINDS SATURDAY WITH GUSTS AROUND 30 MPH POSSIBLE...MAYBE EVEN STRONGER IF THE NCEP GUIDANCE IS ON THE RIGHT TRACK WITH THE DEEPER LOW. MODELS CONTINUE TO HONE IN ON TIMING FRONTAL PASSAGE AND ARE IN DECENT AGREEMENT SHOWING THE FRONT ENTERING THE NORTHWEST CWA SATURDAY EVENING...EXITING THE EASTERN CWA EARLY SUNDAY MORNING. FORECAST SOUNDINGS INDICATE PRETTY POOR MIDLEVEL LAPSE RATES AND LITTLE IF ANY INSTABILITY ALONG AND JUST AHEAD OF THE FRONT...SO EXPECT THE THUNDER THREAT TO BE PRETTY LOW WITH THIS SYSTEM...BUT MOST AREAS SHOULD SEE RAIN WITH THE FRONT. MONDAY THROUGH WEDNESDAY... PATTERN APPEARS ZONAL AND PROGRESSIVE THROUGH NEXT WEEK. HIGH PRESSURE WILL BUILD EAST ACROSS THE CWA MONDAY WITH RETURN FLOW TUESDAY ALLOWING TEMPERATURES TO RETURN TO ABOVE NORMAL CONDITIONS. MODELS IN AGREEMENT THAT ANOTHER FRONT WILL SWEEP ACROSS THE REGION MIDWEEK...THOUGH TIMING AND STRENGTH OF THE SYSTEM THIS FAR OUT IS STILL QUESTIONABLE. DEUBELBEISS && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 00Z... * NONE. MDB //DISCUSSION...UPDATED 00Z... HIGH PRESSURE REMAINS CENTERED OVER EASTERN CANADA WITH NORTHEAST WINDS BEGINNING TO DIMINISH NOW THAT SUNSET IS APPROACHING. WILL MONITOR FOR POSSIBLE FOG DEVELOPMENT OVERNIGHT BUT EXPECT CONDITIONS SIMILAR TO LAST NIGHT WITH SOME MVFR VSBY DEVELOPING AT RFD/DPA. WINDS WILL TURN EAST-SOUTHEAST TO SOUTHEAST AND INCREASE TO NEAR 10 KT THURSDAY MORNING. THE LAKE MAY HELP TO TURN WINDS A BIT MORE EASTERLY AT ORD/MDW BY MID AFTERNOON AND GYY MAY SEE AN EAST-NORTHEAST DIRECTION DEVELOP. WINDS WILL THEN DIMINISH WITH SUNSET AND TREND BACK SOUTHEAST LATER THURSDAY EVENING. ANY MORNING VSBY REDUCTION WILL DISSIPATE LEAVING VFR CONDITIONS. MDB //ORD AND MDW CONFIDENCE...UPDATED 00Z... * HIGH CONFIDENCE ALL ELEMENTS. MDB //OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z... FRIDAY...DRY/VFR. SATURDAY...GUSTY SOUTHERLY WINDS POSSIBLE. CHANCE OF SHRA/TSRA LATE AFTERNOON...LIKELY SATURDAY NIGHT. SUNDAY THROUGH TUESDAY...DRY/VFR. MDB && .MARINE... 302 PM CDT A PERSISTENT LARGE AREA OF HIGH PRESSURE CENTERED OVER THE NORTHERN GREAT LAKES WILL BEGIN TO SLOWLY MOVE EAST THURSDAY AND FRIDAY AS IT STRENGTHENS A BIT MORE. LOW PRESSURE DEVELOPING OVER THE CENTRAL ROCKIES IS EXPECTED TO MOVE OUT INTO THE NORTHERN PLAINS THURSDAY AND CONTINUE INTO MANITOBA THURSDAY NIGHT AND FRIDAY. ANOTHER LOW WILL DEVELOP OVER THE CENTRAL PLAINS THURSDAY NIGHT. THIS LOW WILL THEN ELONGATE INTO A TROUGH OF LOW PRESSURE WITH AN ASSOCIATED COLD FRONT EXTENDING FROM MINNESOTA SOUTHWEST INTO COLORADO. THIS SYSTEM WILL SLOWLY TRACK ACROSS THE PLAINS FRIDAY AND SATURDAY...WITH THE COLD FRONT MOVING ACROSS THE LAKE SATURDAY NIGHT. KREIN && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion National Weather Service Lincoln IL 637 PM CDT Wed Sep 25 2013 .DISCUSSION... ISSUED 308 PM CDT Wed Sep 25 2013 A progressive and high amplitude upper level pattern will give way to more of a semi-zonal flow by late in the weekend into early next week. This pattern will result in temperatures above normal for the rest of the week. Our next chance for much needed rainfall is expected as the pattern transitions to more of a zonal flow due to an upper trough quickly lifts across the upper Midwest later Saturday. From about Tuesday and beyond, the medium range models diverge significantly in their upper level patterns and associated temperature fields. SHORT TERM...Tonight through Friday night Some lingering low level moisture, a light easterly flow and a more extensive cu field in southeast IL this afternoon will set the stage for patchy fog mainly south of I-70 overnight. Forecast NAM soundings indicate a stronger inversion and a bit more low level moisture and fog in southeast IL as opposed to central IL, where only a few spots of very shallow ground fog are possible. From Thursday through Friday, high pressure centered in Quebec will have ridging extend back into the Midwest. Aloft, upper level ridging/heights will build, allowing warm conditions to return. The result of this will be a mostly sunny sky with above normal temperatures in the lower to middle 80s. LONG TERM...Saturday through Wednesday The models are in pretty good agreement regarding the timing of an ejecting trough from the southwest U.S. and its associated cold front. It still appears that the vast majority of the rain will be along and behind the cold front. The NAM is the quickest model with the advancing rain chances, with the GFS, Canadian and European a bit slower. Prefer the slightly slow solutions with the rain along and west of the IL River valley later Saturday afternoon, and moving into the rest of central and eastern IL Saturday evening. The models also agree the rain is not expected to persist very long, with areas west of I-57 ending by daybreak Sunday, and then ending in eastern IL Sunday morning. Instability is expected to be quite limited with this system, so the best chances for thunderstorms will be in west central IL Sat afternoon, with more isolated thunderstorms Sat night and early Sunday. A brief cool down toward more normal temperatures for late September is anticipated behind the cold front Sunday and Monday as high pressure covers the Midwest. By Tuesday though, the European and GFS have very different ideas about our upper level pattern and low level temperature fields. The GFS has more of a light semi-zonal flow aloft with cooler temperatures, while the European tries to build an upper level ridge as it depicts a more vigorous trough digging into the southwestern states. The GFS is showing more run to run consistency with its solution, while the European 12z run is the first one to show these warmer temperatures and stronger ridging in the Midwest. Thus, will be more conservative with temperatures for Tuesday and Wednesday, but still go a few degrees above normal. Neither model is indicating much of a potential for precipitation Monday through Wednesday in central or southeast IL, so will keep the forecast dry for that period. Miller && .AVIATION... ISSUED 637 PM CDT Wed Sep 25 2013 High surface pressure will build into Illinois tonight and tomorrow as a weak low departs toward the East Coast. Ridging aloft will occur over the next 24 hours, helping to provide mostly clear skies through this taf period. The main concern will be some patchy ground fog that may bring mvfr vis to the terminal sites between 11z and 14z. A 3 hour tempo group was added to all tafs for that time period. Upstream dewpoints are in the mid 40s to the northeast, but airmass changes will slow tonight, leaving slightly higher dewpoints in central Illinois. That will set the stage for some fog to develop as favorable radiational cooling conditions allow air temps to drop close to the dewpoint late tonight. Forecast soundings from the NAM and RUC show a shallow low level saturation, lending some confidence in at least a tempo group for mvfr vis. Winds will start our light northeast, then become southeast tomorrow as the ridge axis passes east of Illinois and influences from low pressure in the plains affect the sfc wind pattern. Shimon && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1234 PM CDT WED SEP 25 2013 .DISCUSSION... 350 AM CDT FORECAST CONCERNS CONTINUE TO FOCUS ON QUIET WEATHER WITH A GRADUAL WARMING TREND THROUGH THE END OF THE WEEK...SHIFTING TO TIMING OF COLD FRONT LATE SATURDAY-EARLY SUNDAY AND ASSOCIATED PRECIPITATION CHANCES. ONLY MODEST COOLING EXPECTED BEHIND THE WEEKEND COLD FRONT HOWEVER...WITH TEMPERATURES EXPECTED TO RISE ABOVE NORMAL EARLY NEXT WEEK TO CLOSE OUT SEPTEMBER AND START OCTOBER. SHORT TERM...TODAY THROUGH FRIDAY NIGHT. SURFACE HIGH PRESSURE REMAINS TO OUR NORTHEAST THIS MORNING ACROSS THE NORTHERN AND CENTRAL GREAT LAKES REGION. TO THE SOUTH...AN AREA OF LOW PRESSURE WAS DRIFTING SOUTHEAST ACROSS THE LOWER MISSOURI AND MISSISSIPPI VALLEYS IN ASSOCIATION WITH THE CLOSED MID-LEVEL CIRCULATION OVER SOUTHEAST MISSOURI. AS ANTICIPATED...EASTERLY LOW LEVEL FLOW FROM THE HIGH TO OUR NORTHEAST WAS CONTINUING TO MAINTAIN DRY ADVECTION...WHILE PATCHY MID/HIGH CLOUDS WERE SPREADING ACROSS THE SOUTHERN AND EASTERN PARTS OF THE CWA AROUND THE CYCLONIC CIRCULATION TO OUR SOUTH. LIGHT/CALM WINDS AND SMALL TEMPERATURE-DEW POINT DEPRESSIONS WERE RESULTING IN SOME SHALLOW FOG FORMATION MAINLY WEST OF CHICAGO...WHERE SKIES WERE MAINLY CLEAR AND SURFACE PRESSURE GRADIENT WAS A LITTLE WEAKER. THE UPPER LOW OVER THE LOWER MISSOURI VALLEY WILL MOVE ACROSS THE SOUTHERN TIP OF ILLINOIS THIS MORNING...AND OFF ACROSS THE OHIO VALLEY AND CENTRAL APPALACHIANS TO THE MID-ATLANTIC REGION THROUGH TONIGHT. PATCHY CLOUD COVER WILL CONTINUE TO AFFECT MAINLY THE EAST AND SOUTHEAST PARTS OF THE CWA TODAY AS THE UPPER DISTURBANCE PULLS SLOWLY AWAY...WITH ANY PRECIPITATION REMAINING WELL SOUTH OF THE FORECAST AREA. A LARGE...HIGHLY AMPLIFIED UPPER TROUGH DEVELOPING OVER THE WESTERN CONUS WILL HELP INDUCE RE-DEVELOPMENT OF AN EQUALLY HIGH AMPLITUDE UPPER RIDGE ACROSS THE MISSISSIPPI VALLEY AND WESTERN LAKES REGION TONIGHT AND THURSDAY IN THE WAKE OF THE DEPARTING UPPER LOW. THIS WILL HELP RE-ESTABLISH THE SURFACE RIDGE AXIS FROM THE MID-MISSISSIPPI VALLEY NORTHEAST INTO QUEBEC...MAINTAINING MOSTLY CLEAR SKIES AND EAST-NORTHEAST FLOW WHICH WILL GRADUALLY SHIFT MORE SOUTH-SOUTHEAST THROUGH FRIDAY AS THE UPPER/SURFACE RIDGE AXES DRIFT EAST. THIS WILL ALLOW FOR A SLOW BUT STEADY WARMING TREND TO CONTINUE THROUGH FRIDAY...THOUGH IMPEDED ACROSS NORTHEAST ILLINOIS BY ONSHORE FLOW OFF THE LAKE. TRUE LAKE-COOLING WILL DECREASE A BIT THURSDAY AND MORESO FRIDAY AS SURFACE WIND BECOMES MORE SOUTHEAST. MODELS ARE IN GENERALLY GOOD AGREEMENT THERMALLY...SUPPORTING HIGHS IN THE 70S TODAY AND THURSDAY (THOUGH APPROACHING 80 SOUTH/SOUTHWEST) AND IN THE LOWER 80S MOST AREAS AWAY FROM LAKE MICHIGAN FRIDAY. NIGHTS WILL REMAIN SEASONABLY COOL INITIALLY WITH UPPER 40S AND LOWER 50S FOR LOWS...MODERATING TO MID/UPPER 50S BY FRIDAY MORNING. MID-TERM...SATURDAY/SUNDAY. MODEL GUIDANCE CONTINUES TO ADJUST TIMING OF COLD FRONT OVER THE WEEKEND...WITH RECENT RUNS HAVING SPED UP THE PROGRESSION A BIT SINCE YESTERDAY. 00Z ECMWF THE MOST RECENT TO TREND TOWARD AN EARLIER ARRIVAL OF THE COLD FRONT...SOMETIME SATURDAY EVENING ACROSS NORTHERN IL...AND EXITING NORTHWEST INDIANA EARLY SUNDAY. THIS MOVES UP THE ARRIVAL AND DEPARTURE OF RAIN/SHOWER CHANCES AS WELL...TO SATURDAY AFTERNOON/NIGHT IN THE FAR WEST AND FOR SATURDAY NIGHT AND SUNDAY MORNING IN THE EAST. RECENT MODEL CONSENSUS HAS THE CWA DRY SUNDAY AFTERNOON. STRONG FORCING DEPICTED WITH APPROACH OF UPPER TROUGH AND LOW LEVEL FRONTAL ZONE...ALONG WITH NARROW BAND OF DEEPER MOISTURE (PWATS IN EXCESS OF 1.8 INCHES PER GFS RUNS) RETURNING ALONG THE FRONT SUPPORTS A DECENT CHANCE OF RAIN/SHOWERS WITH THE FRONTAL PASSAGE. LAPSE RATES CONTINUE TO LOOK MEAGER...WITH VERY WEAK/SKINNY CAPE PROFILES SUGGESTING ONLY ISOLATED THUNDER POTENTIAL. SATURDAY CONTINUES TO HAVE THE POTENTIAL TO BE IN THE 80S CWA-WIDE...AS THERMAL RIDGE AHEAD OF THE FRONT SPREADS ACROSS THE AREA AND SOUTH-SOUTHWEST WINDS OVERCOME ANY SIGNIFICANT LAKE COOLING. INCREASING CLOUD COVER WITH BE THE MAIN ISSUE FIGHTING AGAINST THE TEMP CLIMB HOWEVER AND ADDS COMPLEXITY AND LOWER CONFIDENCE TO THE MAX TEMP FORECAST SATURDAY AFTERNOON. WEAK HIGH PRESSURE THEN DEVELOPS IN THE WAKE OF THE COLD FRONT SUNDAY AFTERNOON AND SUNDAY NIGHT...THOUGH AIR BEHIND THE FRONT IS NOT SIGNIFICANTLY COOLER. TEMPS EXPECTED RIGHT AROUND NORMAL (UPPER 60S TO LOWER 70S) SUNDAY. LONG TERM...MONDAY/TUESDAY. LONG RANGE MODELS TREND THE UPPER FLOW MORE ZONAL BEHIND THE WEEKEND TROUGH. WEAK SURFACE HIGH SLIDES OFF TO THE EAST OF THE AREA MONDAY/TUESDAY...ALLOWING A GRADUAL RETURN TO SOUTHEAST AND THEN SOUTH LOW LEVEL FLOW. BOTH GFS/ECMWF INDICATE A TROUGH DEVELOPING ACROSS THE CANADIAN PRAIRIES/NORTHERN PLAINS...WHICH INCREASES SOUTH RETURN FLOW AND WARM ADVECTION. TEMPS LOOK TO CLIMB BACK ABOVE NORMAL MONDAY AND TUESDAY...BACK WELL INTO THE 70S IF NOT A FEW 80S AGAIN BY TUESDAY TO START OCTOBER ON A WARM NOTE. RATZER && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * NONE. JEE //DISCUSSION...UPDATED 18Z... HIGH PRESSURE REMAINS NE OF THE REGION WITH A STRENGTHENING LOW OVER THE ROCKIES. THE HIGH WILL REMAIN RELATIVELY STATIONARY WITH CLEAR SKIES EXPECTED TONIGHT AND THROUGH THE REST OF THE PERIOD. WITH CONDITIONS SIMILAR TO YESTERDAY...EXPECTING MVFR FOG DEVELOPMENT AT DPA AND RFD AGAIN TONIGHT. WITH NO RAIN IN THE PAST 5 DAYS...NOT EXPECTING FOG THICKER THAN MVFR. WINDS WILL REMAIN OUT OF THE E THROUGH THIS EVENING AND THEN BECOMING LIGHT AND VARIABLE OVERNIGHT. EXPECTING E TO SE WINDS TO DEVELOP THURSDAY MORNING WITH SPEEDS ARND 10 KT LATE IN THE MORNING. A LAKE BREEZE IS EXPECTED TOMORROW AND WINDS AT ORD...MDW...AND DPA WILL TURN EAST BEHIND IT. EXPECTING N WINDS AT GYY BEHIND THE LAKE BREEZE. JEE //ORD AND MDW CONFIDENCE...UPDATED 18Z... * MEDIUM CONFIDENCE IN TIMING OF LAKE BREEZE TOMORROW. * HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS. JEE //OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z... * THURSDAY NIGHT THROUGH FRIDAY NIGHT...DRY/VFR. * SATURDAY...GUSTY SOUTHERLY WINDS POSSIBLE. CHANCE OF SHRA/TSRA LATE. * SATURDAY NIGHT...CHANCE OF SHRA/TSRA. * SUNDAY THROUGH TUESDAY...DRY/VFR. && .MARINE... 310 AM...A LARGE AREA OF WEAK HIGH PRESSURE OVER MUCH OF THE GREAT LAKES WILL SLOWLY DRIFT EAST AND STRENGTHEN OVER THE NEXT FEW DAYS AS IT MERGES WITH STRONG HIGH PRESSURE MOVING SOUTH ACROSS QUEBEC. THE GRADIENT WILL REMAIN FAIRLY LIGHT OVER ALL BUT THE SOUTH END OF THE LAKE THROUGH FRIDAY. A SLIGHTLY STRONGER GRADIENT WILL DEVELOP OVER THE SOUTH THIRD OR SO OF THE LAKE LATER TODAY INTO THIS EVENING AND WHILE SPEEDS WILL LIKELY REMAIN 10-20KTS OVER THE NEXT 24-36 HOURS...THIS TIME PERIOD COULD BE MORE IN THE 15-20KT RANGE. WINDS TURN BACK SOUTHEASTERLY THURSDAY NIGHT AND MORE SOUTHERLY INTO FRIDAY NIGHT WHEN SPEEDS BEGIN TO INCREASE. THE GRADIENT WILL TIGHTEN FRIDAY NIGHT INTO SATURDAY AHEAD OF AN APPROACHING COLD FRONT AND THE TIMING OF THIS FRONT HAS VARIED OVER THE PAST FEW DAYS AND NOW HAS SPED UP WITH A FRONTAL PASSAGE SATURDAY NIGHT ACROSS LAKE MICHIGAN. SOUTHERLY WINDS 15-25KTS AHEAD OF THE FRONT APPEAR ON TRACK WITH SOME HIGHER GUSTS POSSIBLE... ESPECIALLY OVER THE NORTHERN PART OF THE LAKE. WINDS WILL LIKELY SHIFT WEST/NORTHWEST BEHIND THE FRONT AND COULD BE SOMEWHAT STRONG BEHIND THE FRONT...BUT DURATION OF STRONGER WINDS LOOKS TO BE BRIEF WITH HIGH PRESSURE QUICKLY BUILDING INTO THE WESTERN LAKES REGION SUNDAY AFTERNOON/EVENING. CMS && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion National Weather Service Lincoln IL 1224 PM CDT Wed Sep 25 2013 .DISCUSSION... ISSUED 1040 AM CDT Wed Sep 25 2013 Latest surface analysis shows 1009mb low centered over northwest Tennessee. Most of the clouds and showers associated with this feature have been confined to Kentucky this morning, however both the HRRR and NAM suggest isolated showers may develop as far north as southern Illinois this afternoon. Diurnal cloud cover has not yet begun to develop, but CU-rule indicates SCT-BKN clouds developing across the southern half of the KILX CWA. Given proximity to lingering low pressure system and presence of slightly more humid airmass with dewpoints in the upper 50s/lower 60s, will maintain slight chance for showers along/south of I-70 through the afternoon. Elsewhere, expect mostly sunny and dry conditions. High temps will be a degree or two warmer than yesterday, generally reaching the upper 70s and lower 80s. Barnes && .AVIATION... ISSUED 1224 PM CDT Wed Sep 25 2013 VFR conditions will prevail through the entire 18z TAF period. SCT Cu will develop across the area this afternoon, primarily along and southeast of a KBMI to KSPI line. This diurnal cloud cover will dissipate prior to sunset, followed by clear skies tonight into Thursday morning. Winds will be northeasterly at 5 to 10kt this afternoon, then will veer to southeasterly on Thursday as high pressure drifts off to the east. Barnes && .PREV DISCUSSION... ISSUED 235 AM CDT Wed Sep 25 2013 Upper low continues to slowly weaken as it moves southeast, and was located just west of Effingham early this morning. Earlier showers and scattered thunderstorms have largely diminished in our area, with radar mosaics showing them continuing in southeast Missouri. Skies mainly partly cloudy west of I-55, with areas to the east under a small but concentrated patch of clouds associated with the upper low. The main forecast challenge remains with the cold front this weekend, and associated rain chances. SHORT TERM...TODAY THROUGH FRIDAY... Will hang on to some slight chance PoPs for the southeast this morning as the remnants of the upper low depart. Most of the model hint at some residual PoPs along the Missouri/Illinois border lingering into this afternoon due to a weak ribbon of energy, but will keep our forecast dry after noon. Otherwise, high pressure over the Great Lakes will control our weather late tonight into Friday. Narrow upper ridge axis overhead will keep mostly clear conditions, with highs mainly in the lower 80s. LONG TERM...SATURDAY THROUGH TUESDAY... Deep upper trough over the western U.S. to flatten out late this week as it moves into the Plains. Models have begun to pick up a bit of speed with this feature as it moves toward the Midwest, with the GFS the most aggressive. Have included some slight chances along the Illinois River Valley Saturday afternoon, but currently appears that the main show will be Saturday night. Have increased rain chances to around 60% across the west half of the CWA, and may need to do this across the east if model trends continue. Currently think most of the rain should be out of the forecast area by midday, with perhaps a few showers lingering south of I-70 into early afternoon. The fly in the ointment may be with a developing low moving northward along the East Coast Saturday night and Sunday. This low may slow the progression of the front a bit, but it currently looks like the front should be east of us before it begins to slow down. Zonal flow sets up for early in the week, with dry weather for Monday and Tuesday. Next rain chance would be toward midweek as a wave moves along the Canadian border, but there is still some uncertainty in that solution. Geelhart && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1252 PM EDT TUE SEP 24 2013 .UPDATE... THE AVIATION SECTION HAS BEEN UPDATED BELOW && .SYNOPSIS... ISSUED AT 313 AM EDT TUE SEP 24 2013 AN UPPER LEVEL LOW ACCOMPANIED BY A SURFACE LOW WILL MOVE THROUGH THE OHIO VALLEY TONIGHT AND WEDNESDAY BRINGING A CHANCE FOR RAIN TO THE AREA. HIGH PRESSURE AND DRY CONDITIONS WILL THEN PERSIST THROUGH THE FIRST HALF OF THE WEEKEND...UNTIL A COLD FRONT BRINGS ANOTHER CHANCE FOR RAIN SATURDAY NIGHT INTO SUNDAY NIGHT. ABOVE AVERAGE TEMPERATURES WILL GIVE WAY TO NEAR AVERAGE READINGS BY SUNDAY. && .NEAR TERM /REST OF TODAY/... ISSUED AT 956 AM EDT TUE SEP 24 2013 .UPDATE... CURRENT FORECAST IS ON TRACK AND NO UPDATES ARE PLANNED AT THIS TIME. ONLY CHANGE TO THE GRIDS WAS TO TWEAK HIGH UP A DEGREE SOUTHWEST AS RAP HAD TEMPERATURES THERE NEAR 80 LATER TODAY. .PREVIOUS NEAR TERM DISCUSSION FOLLOWS... A DRY EASTERLY FLOW WILL CONTINUE ACROSS THE FORECAST AREA DURING THE DAY WITH HIGH PRESSURE OFF TO THE NORTHEAST. THIS WILL KEEP LOW LEVELS PRETTY DRY. MEANWHILE...MID AND HIGH CLOUDS WILL INCREASE THIS AFTERNOON AS AN UPPER SYSTEM AND SURFACE LOW BEGIN THEIR APPROACH. FORCING REMAINS TO THE WEST OF THE AREA UNTIL VERY LATE IN THE TODAY PERIOD. LOW LEVELS REMAIN QUITE DRY THOUGH...SO FEEL THAT ANY CHANCES FOR RAIN ACROSS THE FAR SOUTHWEST FORECAST AREA ARE TOO LOW TO MENTION. WILL CONTINUE WITH A DRY FORECAST ALL AREAS TODAY. A BLEND OF MODEL TEMPERATURES LOOKS GOOD GIVEN EXPECTED CONDITIONS...AND THIS ENDS UP PRETTY CLOSE TO MAV MOS. && .SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/... ISSUED AT 313 AM EDT TUE SEP 24 2013 FOCUS IS ON CHANCES FOR RAIN EARLY IN THE PERIOD. WITH THE BIG PICTURE MODELS ARE CLOSE ENOUGH. HOWEVER NAM LOOKS TO OVERDO LOW LEVEL MOISTURE AS SEEN IN ITS HIGHER DEWPOINT FORECAST. THIS DOESN/T LOOK REASONABLE GIVEN AN EASTERLY COMPONENT TO THE WINDS ACROSS THE AREA THROUGH THE PERIOD. WENT CLOSER TO GFS/ECMWF UNLESS NOTED BELOW. THE SURFACE LOW WILL WEAKEN AS IT MOVES SOUTHWEST OF THE AREA TONIGHT AND WEDNESDAY. MOST OF THE FORCING WILL BE ALOFT WITH THE UPPER LOW. HOWEVER MODEL TIME SECTIONS SHOW THAT BEST MOISTURE DOESN/T LINE UP WITH BEST LIFT. MODEL REFLECTIVITY FORECASTS FROM THE NCEP AND NSSL WRF SHOW LITTLE RAINFALL WITH THE SYSTEM AS WELL. THUS CONFIDENCE FOR GETTING MEASURABLE RAIN IS LOW. WILL UNDERCUT MOS POPS AND GO SLIGHT CHANCE TO LOW CHANCE POPS ACROSS THE SOUTHERN FORECAST AREA TONIGHT INTO WEDNESDAY. INSTABILITY IS MEAGER AT BEST SO WILL CONTINUE TO LEAVE OUT THUNDER MENTION. UPPER RIDGING AND SURFACE HIGH PRESSURE WILL THEN BUILD INTO THE AREA FOR THE REMAINDER OF THE SHORT TERM PROVIDING MOSTLY CLEAR SKIES AND DRY CONDITIONS. FOR TEMPERATURES...GENERALLY STUCK WITH A BLEND OF MODELS...WHICH ENDS UP NOT TOO FAR OFF FROM MAV MOS. && .LONG TERM /FRIDAY THROUGH MONDAY/... ISSUED AT 243 AM EDT TUE SEP 24 2013 RIDGING ALOFT AND A STRONG SURFACE HIGH PRESSURE RIDGE WILL REMAIN THE MAIN INFLUENCES ON WEATHER OVER THE OHIO VALLEY FRIDAY THROUGH THE FIRST HALF OF THE WEEKEND. WARM DRY WEATHER WILL CONTINUE ACROSS THE REGION...HIGHLIGHTED BY MAINLY CLEAR SKIES AND TEMPS IN THE UPPER 70S AND LOWER 80S FRIDAY AND SATURDAY. EXTENDED MODEL GUIDANCE HAS CONTINUED TO SLOW THE APPROACH AND ARRIVAL OF A COLD FRONT...WITH THE ECMWF...OP GFS AND GFS ENSEMBLE MEAN ALL FAVORING BULK OF THE PRECIP COMING SUNDAY AS THE FRONT SWINGS INTO THE OHIO VALLEY. FAVOR THE SLOWER SOLUTION CONSIDERING THE OVERALL STRENGTH OF THE RIDGING ALOFT AND SURFACE HIGH...AND THE TENDENCY FOR MODELS TO UNDERESTIMATE THAT STRENGTH AND BREAK DOWN RIDGING TOO QUICKLY THIS FAR OUT. HAVE CUT BACK ON ALLBLEND POPS SUBSTANTIALLY FOR SATURDAY NIGHT...KEEPING ONLY LOW CHANCE POPS OVER THE NORTHERN WABASH VALLEY. WILL CONTINUE WITH 40-50 POPS SUNDAY WITH POPS DIMINISHING FROM WEST TO EAST SUNDAY NIGHT AS THE FRONT SHIFTS EAST. WITH LITTLE INSTABILITY ACCOMPANYING THE BOUNDARY...WILL ONLY CARRY ISOLATED THUNDER ON SUNDAY. HIGH PRESSURE WILL RETURN TO BEGIN NEXT WEEK. HIGH TEMPS ARE LIKELY TO FALL BACK INTO THE UPPER 60S AND LOWER 70S FOR MONDAY AND TUESDAY AS COLD ADVECTION DEVELOPS IN WAKE OF THE FRONTAL PASSAGE. && .AVIATION /DISCUSSION FOR THE 24/1800Z TAF ISSUANCE/... ISSUED AT 1242 PM EDT TUE SEP 24 2013 VFR CONDITIONS ARE EXPECTED TO BE THE PREDOMINANT FLIGHT CATEGORY FOR MAJORITY OF TAF PERIOD. THE ONLY EXCEPTION WILL BE AT KHUF AND KBMG LATE IN TAF PERIOD WHERE CONDITIONS WILL BE CLOSE TO THE VFR/MVFR MARK AS AN UPPER LEVEL WAVE TRIGGERS LIGHT RAIN SHOWERS. INCLUDED MENTION OF VCSH AT KBMG AND KHUF TOMORROW MORNING...BUT CONFIDENCE IS LOW DUE TO LACK OF MOISTURE. WINDS WILL START OUT SOUTHEASTERLY AT BEGINNING OF TAF PERIOD AND BACK SLIGHTLY TO THE EAST/NORTHEAST THROUGH THE COURSE OF THE PERIOD. SUSTAINED SPEEDS WILL RANGE BETWEEN 4 TO 8 KTS. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS...50 NEAR TERM...50/JH SHORT TERM...50 LONG TERM....RYAN AVIATION...TDUD VISIT US AT HTTP://WWW.WEATHER.GOV/IND FOLLOW US ON TWITTER AND YOUTUBE AT: WWW.TWITTER.COM/NWSINDIANAPOLIS WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1013 AM EDT TUE SEP 24 2013 .UPDATE... THE AVIATION SECTION HAS BEEN UPDATED BELOW && .SYNOPSIS... ISSUED AT 313 AM EDT TUE SEP 24 2013 AN UPPER LEVEL LOW ACCOMPANIED BY A SURFACE LOW WILL MOVE THROUGH THE OHIO VALLEY TONIGHT AND WEDNESDAY BRINGING A CHANCE FOR RAIN TO THE AREA. HIGH PRESSURE AND DRY CONDITIONS WILL THEN PERSIST THROUGH THE FIRST HALF OF THE WEEKEND...UNTIL A COLD FRONT BRINGS ANOTHER CHANCE FOR RAIN SATURDAY NIGHT INTO SUNDAY NIGHT. ABOVE AVERAGE TEMPERATURES WILL GIVE WAY TO NEAR AVERAGE READINGS BY SUNDAY. && .NEAR TERM /REST OF TODAY/... ISSUED AT 956 AM EDT TUE SEP 24 2013 .UPDATE... CURRENT FORECAST IS ON TRACK AND NO UPDATES ARE PLANNED AT THIS TIME. ONLY CHANGE TO THE GRIDS WAS TO TWEAK HIGH UP A DEGREE SOUTHWEST AS RAP HAD TEMPERATURES THERE NEAR 80 LATER TODAY. .PREVIOUS NEAR TERM DISCUSSION FOLLOWS... A DRY EASTERLY FLOW WILL CONTINUE ACROSS THE FORECAST AREA DURING THE DAY WITH HIGH PRESSURE OFF TO THE NORTHEAST. THIS WILL KEEP LOW LEVELS PRETTY DRY. MEANWHILE...MID AND HIGH CLOUDS WILL INCREASE THIS AFTERNOON AS AN UPPER SYSTEM AND SURFACE LOW BEGIN THEIR APPROACH. FORCING REMAINS TO THE WEST OF THE AREA UNTIL VERY LATE IN THE TODAY PERIOD. LOW LEVELS REMAIN QUITE DRY THOUGH...SO FEEL THAT ANY CHANCES FOR RAIN ACROSS THE FAR SOUTHWEST FORECAST AREA ARE TOO LOW TO MENTION. WILL CONTINUE WITH A DRY FORECAST ALL AREAS TODAY. A BLEND OF MODEL TEMPERATURES LOOKS GOOD GIVEN EXPECTED CONDITIONS...AND THIS ENDS UP PRETTY CLOSE TO MAV MOS. && .SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/... ISSUED AT 313 AM EDT TUE SEP 24 2013 FOCUS IS ON CHANCES FOR RAIN EARLY IN THE PERIOD. WITH THE BIG PICTURE MODELS ARE CLOSE ENOUGH. HOWEVER NAM LOOKS TO OVERDO LOW LEVEL MOISTURE AS SEEN IN ITS HIGHER DEWPOINT FORECAST. THIS DOESN/T LOOK REASONABLE GIVEN AN EASTERLY COMPONENT TO THE WINDS ACROSS THE AREA THROUGH THE PERIOD. WENT CLOSER TO GFS/ECMWF UNLESS NOTED BELOW. THE SURFACE LOW WILL WEAKEN AS IT MOVES SOUTHWEST OF THE AREA TONIGHT AND WEDNESDAY. MOST OF THE FORCING WILL BE ALOFT WITH THE UPPER LOW. HOWEVER MODEL TIME SECTIONS SHOW THAT BEST MOISTURE DOESN/T LINE UP WITH BEST LIFT. MODEL REFLECTIVITY FORECASTS FROM THE NCEP AND NSSL WRF SHOW LITTLE RAINFALL WITH THE SYSTEM AS WELL. THUS CONFIDENCE FOR GETTING MEASURABLE RAIN IS LOW. WILL UNDERCUT MOS POPS AND GO SLIGHT CHANCE TO LOW CHANCE POPS ACROSS THE SOUTHERN FORECAST AREA TONIGHT INTO WEDNESDAY. INSTABILITY IS MEAGER AT BEST SO WILL CONTINUE TO LEAVE OUT THUNDER MENTION. UPPER RIDGING AND SURFACE HIGH PRESSURE WILL THEN BUILD INTO THE AREA FOR THE REMAINDER OF THE SHORT TERM PROVIDING MOSTLY CLEAR SKIES AND DRY CONDITIONS. FOR TEMPERATURES...GENERALLY STUCK WITH A BLEND OF MODELS...WHICH ENDS UP NOT TOO FAR OFF FROM MAV MOS. && .LONG TERM /FRIDAY THROUGH MONDAY/... ISSUED AT 243 AM EDT TUE SEP 24 2013 RIDGING ALOFT AND A STRONG SURFACE HIGH PRESSURE RIDGE WILL REMAIN THE MAIN INFLUENCES ON WEATHER OVER THE OHIO VALLEY FRIDAY THROUGH THE FIRST HALF OF THE WEEKEND. WARM DRY WEATHER WILL CONTINUE ACROSS THE REGION...HIGHLIGHTED BY MAINLY CLEAR SKIES AND TEMPS IN THE UPPER 70S AND LOWER 80S FRIDAY AND SATURDAY. EXTENDED MODEL GUIDANCE HAS CONTINUED TO SLOW THE APPROACH AND ARRIVAL OF A COLD FRONT...WITH THE ECMWF...OP GFS AND GFS ENSEMBLE MEAN ALL FAVORING BULK OF THE PRECIP COMING SUNDAY AS THE FRONT SWINGS INTO THE OHIO VALLEY. FAVOR THE SLOWER SOLUTION CONSIDERING THE OVERALL STRENGTH OF THE RIDGING ALOFT AND SURFACE HIGH...AND THE TENDENCY FOR MODELS TO UNDERESTIMATE THAT STRENGTH AND BREAK DOWN RIDGING TOO QUICKLY THIS FAR OUT. HAVE CUT BACK ON ALLBLEND POPS SUBSTANTIALLY FOR SATURDAY NIGHT...KEEPING ONLY LOW CHANCE POPS OVER THE NORTHERN WABASH VALLEY. WILL CONTINUE WITH 40-50 POPS SUNDAY WITH POPS DIMINISHING FROM WEST TO EAST SUNDAY NIGHT AS THE FRONT SHIFTS EAST. WITH LITTLE INSTABILITY ACCOMPANYING THE BOUNDARY...WILL ONLY CARRY ISOLATED THUNDER ON SUNDAY. HIGH PRESSURE WILL RETURN TO BEGIN NEXT WEEK. HIGH TEMPS ARE LIKELY TO FALL BACK INTO THE UPPER 60S AND LOWER 70S FOR MONDAY AND TUESDAY AS COLD ADVECTION DEVELOPS IN WAKE OF THE FRONTAL PASSAGE. && .AVIATION /DISCUSSION FOR THE 24/1500Z TAF UPDATE/... ISSUED AT 1011 AM EDT TUE SEP 24 2013 UPDATE... NO CHANGES. PREVIOUS DISCUSSION... VFR CONDITIONS EXPECTED THROUGHOUT THE FORECAST PERIOD. CLEAR SKIES EARLY THIS MORNING WITH LIGHT EASTERLY FLOW. HAVE NOTICED AN INCREASE IN STRATOCU ACROSS THE LOWER OHIO VALLEY OVER THE LAST COUPLE HOURS AS THE UPPER WAVE APPROACHING FROM THE WEST BEGINS TO INTERACT WITH MOISTURE LIFTING NORTH OUT OF THE LOWER MISSISSIPPI VALLEY. EXPECT THIS TREND TO CONTINUE WITH A GRADUAL INCREASE IN CLOUDS ACROSS THE OHIO VALLEY INTO THE AFTERNOON AS THE UPPER WAVE NEARS THE REGION. WITH THAT BEING SAID...BELIEVE BULK OF THE MODEL DATA THIS MORNING IS OVERDOING MOISTURE ADVECTION INTO CENTRAL INDIANA LATER TODAY. MODEL SOUNDINGS SHOWING AN ABUNDANCE OF DRY AIR AND DEEP SUBSIDENCE WHICH WILL BE DIFFICULT TO BUDGE WITH PERSISTENT LOW LEVEL EASTERLY FLOW. EXPECT SCATTERED VFR CU/STRATOCU TO EXPAND NORTH BY MIDDAY WITH MID LEVEL CLOUDS INCREASING BY LATE AFTERNOON AS WELL. CLOUD COVERAGE WILL INCREASE FURTHER TONIGHT AS THE UPPER WAVE MOVES INTO THE REGION. NOT ENTIRELY CONVINCED THAT THE BOUNDARY LAYER WILL COMPLETELY MOISTEN...WITH THE PREDOMINANT DECK LIKELY TO BE IN THE MID LEVELS WHERE MOISTURE WILL BE MORE PREVALENT. COULD SEE A FEW SHOWERS...ESPECIALLY AT KBMG AND POSSIBLY AT KHUF. COVERAGE TOO SPARSE TO INCLUDE A MENTION IN THE FORECASTS AT THIS TIME. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS...50 NEAR TERM...50/JH SHORT TERM...50 LONG TERM....RYAN AVIATION...RYAN/TDUD VISIT US AT HTTP://WWW.WEATHER.GOV/IND FOLLOW US ON TWITTER AND YOUTUBE AT: WWW.TWITTER.COM/NWSINDIANAPOLIS WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
956 AM EDT TUE SEP 24 2013 .UPDATE... NEAR TERM FOR THE REST OF TODAY HAS BEEN UPDATED BELOW. && .SYNOPSIS... ISSUED AT 313 AM EDT TUE SEP 24 2013 AN UPPER LEVEL LOW ACCOMPANIED BY A SURFACE LOW WILL MOVE THROUGH THE OHIO VALLEY TONIGHT AND WEDNESDAY BRINGING A CHANCE FOR RAIN TO THE AREA. HIGH PRESSURE AND DRY CONDITIONS WILL THEN PERSIST THROUGH THE FIRST HALF OF THE WEEKEND...UNTIL A COLD FRONT BRINGS ANOTHER CHANCE FOR RAIN SATURDAY NIGHT INTO SUNDAY NIGHT. ABOVE AVERAGE TEMPERATURES WILL GIVE WAY TO NEAR AVERAGE READINGS BY SUNDAY. && .NEAR TERM /REST OF TODAY/... ISSUED AT 956 AM EDT TUE SEP 24 2013 .UPDATE... CURRENT FORECAST IS ON TRACK AND NO UPDATES ARE PLANNED AT THIS TIME. ONLY CHANGE TO THE GRIDS WAS TO TWEAK HIGH UP A DEGREE SOUTHWEST AS RAP HAD TEMPERATURES THERE NEAR 80 LATER TODAY. .PREVIOUS NEAR TERM DISCUSSION FOLLOWS... A DRY EASTERLY FLOW WILL CONTINUE ACROSS THE FORECAST AREA DURING THE DAY WITH HIGH PRESSURE OFF TO THE NORTHEAST. THIS WILL KEEP LOW LEVELS PRETTY DRY. MEANWHILE...MID AND HIGH CLOUDS WILL INCREASE THIS AFTERNOON AS AN UPPER SYSTEM AND SURFACE LOW BEGIN THEIR APPROACH. FORCING REMAINS TO THE WEST OF THE AREA UNTIL VERY LATE IN THE TODAY PERIOD. LOW LEVELS REMAIN QUITE DRY THOUGH...SO FEEL THAT ANY CHANCES FOR RAIN ACROSS THE FAR SOUTHWEST FORECAST AREA ARE TOO LOW TO MENTION. WILL CONTINUE WITH A DRY FORECAST ALL AREAS TODAY. A BLEND OF MODEL TEMPERATURES LOOKS GOOD GIVEN EXPECTED CONDITIONS...AND THIS ENDS UP PRETTY CLOSE TO MAV MOS. && .SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/... ISSUED AT 313 AM EDT TUE SEP 24 2013 FOCUS IS ON CHANCES FOR RAIN EARLY IN THE PERIOD. WITH THE BIG PICTURE MODELS ARE CLOSE ENOUGH. HOWEVER NAM LOOKS TO OVERDO LOW LEVEL MOISTURE AS SEEN IN ITS HIGHER DEWPOINT FORECAST. THIS DOESN/T LOOK REASONABLE GIVEN AN EASTERLY COMPONENT TO THE WINDS ACROSS THE AREA THROUGH THE PERIOD. WENT CLOSER TO GFS/ECMWF UNLESS NOTED BELOW. THE SURFACE LOW WILL WEAKEN AS IT MOVES SOUTHWEST OF THE AREA TONIGHT AND WEDNESDAY. MOST OF THE FORCING WILL BE ALOFT WITH THE UPPER LOW. HOWEVER MODEL TIME SECTIONS SHOW THAT BEST MOISTURE DOESN/T LINE UP WITH BEST LIFT. MODEL REFLECTIVITY FORECASTS FROM THE NCEP AND NSSL WRF SHOW LITTLE RAINFALL WITH THE SYSTEM AS WELL. THUS CONFIDENCE FOR GETTING MEASURABLE RAIN IS LOW. WILL UNDERCUT MOS POPS AND GO SLIGHT CHANCE TO LOW CHANCE POPS ACROSS THE SOUTHERN FORECAST AREA TONIGHT INTO WEDNESDAY. INSTABILITY IS MEAGER AT BEST SO WILL CONTINUE TO LEAVE OUT THUNDER MENTION. UPPER RIDGING AND SURFACE HIGH PRESSURE WILL THEN BUILD INTO THE AREA FOR THE REMAINDER OF THE SHORT TERM PROVIDING MOSTLY CLEAR SKIES AND DRY CONDITIONS. FOR TEMPERATURES...GENERALLY STUCK WITH A BLEND OF MODELS...WHICH ENDS UP NOT TOO FAR OFF FROM MAV MOS. && .LONG TERM /FRIDAY THROUGH MONDAY/... ISSUED AT 243 AM EDT TUE SEP 24 2013 RIDGING ALOFT AND A STRONG SURFACE HIGH PRESSURE RIDGE WILL REMAIN THE MAIN INFLUENCES ON WEATHER OVER THE OHIO VALLEY FRIDAY THROUGH THE FIRST HALF OF THE WEEKEND. WARM DRY WEATHER WILL CONTINUE ACROSS THE REGION...HIGHLIGHTED BY MAINLY CLEAR SKIES AND TEMPS IN THE UPPER 70S AND LOWER 80S FRIDAY AND SATURDAY. EXTENDED MODEL GUIDANCE HAS CONTINUED TO SLOW THE APPROACH AND ARRIVAL OF A COLD FRONT...WITH THE ECMWF...OP GFS AND GFS ENSEMBLE MEAN ALL FAVORING BULK OF THE PRECIP COMING SUNDAY AS THE FRONT SWINGS INTO THE OHIO VALLEY. FAVOR THE SLOWER SOLUTION CONSIDERING THE OVERALL STRENGTH OF THE RIDGING ALOFT AND SURFACE HIGH...AND THE TENDENCY FOR MODELS TO UNDERESTIMATE THAT STRENGTH AND BREAK DOWN RIDGING TOO QUICKLY THIS FAR OUT. HAVE CUT BACK ON ALLBLEND POPS SUBSTANTIALLY FOR SATURDAY NIGHT...KEEPING ONLY LOW CHANCE POPS OVER THE NORTHERN WABASH VALLEY. WILL CONTINUE WITH 40-50 POPS SUNDAY WITH POPS DIMINISHING FROM WEST TO EAST SUNDAY NIGHT AS THE FRONT SHIFTS EAST. WITH LITTLE INSTABILITY ACCOMPANYING THE BOUNDARY...WILL ONLY CARRY ISOLATED THUNDER ON SUNDAY. HIGH PRESSURE WILL RETURN TO BEGIN NEXT WEEK. HIGH TEMPS ARE LIKELY TO FALL BACK INTO THE UPPER 60S AND LOWER 70S FOR MONDAY AND TUESDAY AS COLD ADVECTION DEVELOPS IN WAKE OF THE FRONTAL PASSAGE. && .AVIATION /DISCUSSION FOR 241200Z TAF ISSUANCE/... ISSUED AT 603 AM EDT TUE SEP 24 2013 VFR CONDITIONS EXPECTED THROUGHOUT THE FORECAST PERIOD. CLEAR SKIES EARLY THIS MORNING WITH LIGHT EASTERLY FLOW. HAVE NOTICED AN INCREASE IN STRATOCU ACROSS THE LOWER OHIO VALLEY OVER THE LAST COUPLE HOURS AS THE UPPER WAVE APPROACHING FROM THE WEST BEGINS TO INTERACT WITH MOISTURE LIFTING NORTH OUT OF THE LOWER MISSISSIPPI VALLEY. EXPECT THIS TREND TO CONTINUE WITH A GRADUAL INCREASE IN CLOUDS ACROSS THE OHIO VALLEY INTO THE AFTERNOON AS THE UPPER WAVE NEARS THE REGION. WITH THAT BEING SAID...BELIEVE BULK OF THE MODEL DATA THIS MORNING IS OVERDOING MOISTURE ADVECTION INTO CENTRAL INDIANA LATER TODAY. MODEL SOUNDINGS SHOWING AN ABUNDANCE OF DRY AIR AND DEEP SUBSIDENCE WHICH WILL BE DIFFICULT TO BUDGE WITH PERSISTENT LOW LEVEL EASTERLY FLOW. EXPECT SCATTERED VFR CU/STRATOCU TO EXPAND NORTH BY MIDDAY WITH MID LEVEL CLOUDS INCREASING BY LATE AFTERNOON AS WELL. CLOUD COVERAGE WILL INCREASE FURTHER TONIGHT AS THE UPPER WAVE MOVES INTO THE REGION. NOT ENTIRELY CONVINCED THAT THE BOUNDARY LAYER WILL COMPLETELY MOISTEN...WITH THE PREDOMINANT DECK LIKELY TO BE IN THE MID LEVELS WHERE MOISTURE WILL BE MORE PREVALENT. COULD SEE A FEW SHOWERS...ESPECIALLY AT KBMG AND POSSIBLY AT KHUF. COVERAGE TOO SPARSE TO INCLUDE A MENTION IN THE FORECASTS AT THIS TIME. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS...50 NEAR TERM...50/JH SHORT TERM...50 LONG TERM....RYAN AVIATION...RYAN VISIT US AT HTTP://WWW.WEATHER.GOV/IND FOLLOW US ON TWITTER AND YOUTUBE AT: WWW.TWITTER.COM/NWSINDIANAPOLIS WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1146 PM MDT MON SEP 23 2013 .UPDATE... ISSUED AT 707 PM MDT MON SEP 23 2013 UPDATED TO EXPIRE THE WIND ADVISORY AND HIGH WIND WARNING ACROSS THE FORECAST AREA. THE WINDS SHOULD CONTINUE TO DIMINISH ACROSS THE REGION OVERNIGHT AND THROUGH THE DAY ON TUESDAY AS THE LOW PRESSURE AREA MOVES EAST AND IS REPLACED BY HIGH PRESSURE. && .SHORT TERM...(THIS EVENING THROUGH TUESDAY) ISSUED AT 239 PM MDT MON SEP 23 2013 UPPER FLOW WILL BE NORTHWEST TONIGHT AND TUESDAY AS THE UPPER LOW MOVES NORTHEAST INTO IOWA. SURFACE HIGH PRESSURE WILL MOVE INTO THE CENTRAL PLAINS. AS THE UPPER LOW LIFTS OUTS THIS EVENING ANY REMAINING SHOWERS WILL EXIT THE FA. SUBSIDENCE WILL FOLLOW AND CONTINUE THROUGH TUESDAY. OTHER THAN SOME SLIGHT CHANCE POPS EARLY THIS EVENING, POPS WILL BE NIL FOR THE REMAINDER OF THIS PART OF THE FORECAST. HRRR AND RUC MODELS INDICATE STRONG WINDS WILL CONTINUE UNTIL AROUND 01Z. PLAN TO CONTINUE HIGH WIND WARNING AND WIND ADVISORY UNTIL 01Z TUESDAY. GUSTY NORTHWEST WIND WILL DECREASE AROUND SUNSET. MIN TEMPERATURES WILL BE COOL TONIGHT WITH READINGS RANGING FROM THE MID 40S IN EASTERN COLORADO TO AROUND 50 IN THE EASTERN FA. MAX TEMPERATURES TUESDAY WILL WARM INTO THE MID/UPPER 70S. .LONG TERM...(TUESDAY NIGHT THROUGH MONDAY) ISSUED AT 239 PM MDT MON SEP 23 2013 A BRIEF PERIOD OF SHORTWAVE RIDGING WILL CONTINUE TUESDAY NIGHT INTO WEDNESDAY...LEADING TO DRY WEATHER. AS STATED ABOVE...BRIEF IS THE KEY WORD AS THE NEXT LARGE TROUGH OF LOW PRESSURE DEVELOPS OVER THE WESTERN UNITED STATES AND HEADS EAST. AHEAD OF THE UPPER LEVEL TROUGH...A WARMING TREND IS FORECAST UNDER A WARM AIR ADVECTION REGIME OF SOUTH WINDS. HIGH TEMPERATURES ARE EXPECTED TO CLIMB INTO THE MID 80S ON WEDNESDAY AND MID TO UPPER 80S...POSSIBLY NEAR 90...ON THURSDAY. ALSO...PRESSURE GRADIENTS ARE EXPECTED TO TIGHTEN ON WEDNESDAY WHICH WILL RESULT IN A PERIOD OF BREEZY TO POSSIBLY WINDY CONDITIONS DURING THE DAY AND EARLY EVENING. A LEE TROUGH IS INDICATED BY MODELS TO MOVE IN ON THURSDAY...BRINGING A WIND SHIFT AND COOLER TEMPERATURES TO NORTHEAST COLORADO. AHEAD OF THE LEE TROUGH...IT IS POSSIBLE A FEW SHOWERS...POSSIBLY A THUNDERSTORM...COULD DEVELOP FOR THURSDAY AFTERNOON AND THURSDAY NIGHT. AS THE UPPER LEVEL TROUGH EJECTS ACROSS THE NORTHERN PLAINS...A COLD FRONT WILL BE FORCED DOWN ACROSS THE TRI-STATE AREA. THERE ARE SOME LARGE TIMING DIFFERENCES BETWEEN MODELS AT THE PRESENT TIME...LEADING TO WIND AND TEMPERATURE FIELDS LACKING IN AGREEMENT AS WELL. THEREFORE...DID NOT STRAY TOO MUCH FROM THE MIDDLE GROUND OF THE MODELS FOR THIS NEXT SYSTEM. THE MIDDLE GROUND PLACES FRONTAL PASSAGE EARLY IN THE DAY ON FRIDAY. EITHER WAY...THERE WILL BE A GOOD CHANCE FOR SHOWERS AND POSSIBLY A FEW RUMBLES OF THUNDER FOR FRIDAY NIGHT BEHIND THE FRONT. A FEW ISOLATED SHOWERS AND STORMS ARE POSSIBLE AHEAD OF THE FRONT BUT THE MAJORITY OF THE ACTIVITY SHOULD STAY TO THE SOUTHEAST WHERE INSTABILITY IS PROJECTED TO BE HIGHER. IN ADDITION...TEMPERATURES COOL DRAMATICALLY AGAIN BEHIND THE COLD FRONT. HIGH TEMPERATURES ON FRIDAY WILL RANGE FROM THE LOW 60S TO THE UPPER 70S FROM NORTHWEST TO SOUTHEAST. COOL...NEAR TO JUST BELOW NORMAL TEMPERATURES WILL CONTINUE INTO THE WEEKEND AS SURFACE HIGH PRESSURE BUILDS IN FROM THE WEST. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT) ISSUED AT 1132 PM MDT MON SEP 23 2013 A FEW LOWER CLOUDS WITH OCCASIONAL MVFR CEILINGS CIRCULATING AROUND THE LOW PRESSURE CENTER OVER SOUTH CENTRAL NEBRASKA MAY MOVE THROUGH THE MCK TAF AREA BETWEEN 06Z-07Z...BUT SHOULD MOVE OUT OF THE AREA QUICKLY FOR CLEAR SKIES AND VFR CONDITIONS THROUGH THE REMAINDER OF THE TAF PERIOD AS THE LOW CENTER CONTINUES TO MOVE EAST AND IS REPLACED BY HIGH PRESSURE. GLD WILL START OUT AND REMAIN VFR THROUGH THE PERIOD. GLD WILL FLIRT WITH LLWS WITH NORTH NORTHWEST WINDS OF 30-50KTS WITHIN ABOUT 1K FT OFF THE SURFACE...BUT EXPECT WINDS AT THE SURFACE AND ALOFT TO DECREASE THROUGH THE NIGHT AT BOTH MCK AND GLD WITH THE DECREASING PRESSURE GRADIENT AS THE LOW MOVES OUT OF THE REGION. WINDS AFTER 18Z WILL BECOME LIGHT AND VARIABLE AND TURN TO THE SOUTHEAST AFTER 03Z AS A LEE TROUGH BEGINS TO DEEPEN ALONG THE FRONT RANGE. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...LOCKHART SHORT TERM...FS LONG TERM...RRH AVIATION...LOCKHART
AREA FORECAST DISCUSSION
NWS SHREVEPORT LA
1058 AM CDT TUE SEP 24 2013 .DISCUSSION... PRETTY STRAIGHT FORWARD BACK EDGE OF CLOUDS DRAPED FROM SE AR...ACROSS NE/CEN LA AND DEEP E TX. AS FOR THE MORNING RAINFALL...WE SEE THE BACK EDGE FROM JENA...TO JUST SOUTH OF KISATCHIE. THE NAM 12Z IS DRY FOR THE REST OF THE DAY AND WOULD TEND TO AGREE...BUT RAP DOES KEEP A SLIGHT BIT OF QPF OVER THE AFORE MENTIONED CLOUD AREAS INTO THE MID AFTERNOON AS A SECONDARY SHARP TROUGH DROPS QUICKLY INTO PLAY DUE TO THE NEGATIVE TILT OF THE PARENT VORT OVER MO. IT/S INITIAL AXIS THAT DEVELOPED ALL OF THIS MORNING/S RAIN IS LOCATED FROM MEMPHIS...TO VICKSBURG...TO LUFKIN. THIS SECOND PUSH EXTENDS FROM NW AR INTO SE OK AND WILL SCOUR ANY REMAINING MOISTURE SHORTLY. CLEARLY...THERE IS NOT MUCH MOISTURE IN THE MID OR UPPER LEVELS...BUT SFC TDS REMAIN HIGH OVER OUR SE QUAD THROUGH THE AFTERNOON WITH STRONGER SFC WINDS NOW OVER OKC KNOCKING ON OUR NW DOOR. A SPOTTY CU FIELD MAY BE REVEALED LATER THIS AFTERNOON. WE HAVE MADE SOME ADJUSTMENTS TO HIGHS CONSIDERING CURRENT READINGS...AND IN THE LIGHT WIND ENVIRONMENT SHOULD TACK ON ANOTHER 10 DEGREES OR SO BY MID AFTERNOON AHEAD OF ANY MIXING LOW LEVEL WINDS. THE SLIGHT CHANCE OF ADDITIONAL SHOWERS OR ISOLATED THUNDERSTORMS COULD END BEFORE OUR NEXT PRODUCT ISSUANCE. /24/ && .AVIATION... MAINLY VFR FLIGHT CONDITIONS EXPECTED DURING THE UPCOMING 24 HOUR TAF PERIOD ENDING 25/18Z. NORTHWEST WINDS UP TO 10 KNOTS TODAY TO DIMINISH TO AROUND 5 KNOTS OVERNIGHT AND INCREASE SLIGHTLY TO 5 TO 10 KNOTS ON WEDNESDAY. /05/ && .PREV DISCUSSION... /ISSUED 601 AM CDT TUE SEP 24 2013/ DISCUSSION... CURRENT RADAR COVERAGE WARRANTS A QUICK UPDATE TO RAISE POPS ACROSS N CENTRAL LA/SRN AR FOR TODAY. WITH RADAR TRENDS ON THE UPTICK...LIKELY POPS SEEM TO BE A GOOD FIT. EXPECT THAT COVERAGE WILL BEGIN DECREASING THIS AFTERNOON...AS THE UPPER LOW MOVES EWD AWAY FROM THE REGION. UPDATED PRODUCTS ALREADY OUT. /12/ PREV DISCUSSION... /ISSUED 338 AM CDT TUE SEP 24 2013/ DISCUSSION... MOISTURE FROM A SFC LOW IN THE COASTAL BEND REGION OF THE WRN GULF IS INTERACTING WITH A NEGATIVELY TILTED UPPER TROF MOVING ACROSS THE PLAINS THIS MORNING...PRODUCING SHOWERS AND ISOLD THUNDERSTORMS ACROSS THE ERN HALF OF THE REGION. MODELS A BIT MORE AGGRESSIVE THIS RUN WITH PRECIP FOR THESE AREAS TODAY...AND HAVE ADJUSTED UPWARDS ACCORDINGLY...ESPECIALLY ACROSS N CENTRAL LA. UPPER TROF IS FCST TO PUSH EWD TODAY...WITH RAIN ENDING BY THIS EVENING. UPPER RIDGE WILL MOVE BACK OVHD BY MID WEEK...KEEPING US DRY AND ABOVE NORMAL TEMP-WISE THROUGH FRIDAY...AHEAD OF ANOTHER DISTURBANCE AND COLD FRONT SWEEPING ACROSS THE PLAINS. TIMING OF THE ARRIVAL OF THE FRONT AND ASSOCIATED CONVECTION DIFFERS BETWEEN THE GFS AND EURO...WITH THE EURO BRINGING IT IN A LITTLE EARLIER. AT ANY RATE...BOTH MODELS SHOW DECENT QPF WITH THE FRONT AS EARLY AS SATURDAY AFTERNOON...AND CONTINUING THROUGH AT LEAST THE FIRST HALF OF MONDAY. HAVE PRETTY MUCH STUCK WITH THE ONGOING CONSERVATIVE POPS FOR THIS TIMEFRAME DUE TO THE UNCERTAINTY IN TIMING. IN THE WAKE OF THE FRONT...TEMPS ARE EXPECTED TO RETURN TO NEAR OR JUST BELOW NORMAL FOR SUNDAY THROUGH THE END OF THE PD. /12/ AVIATION... MOSTLY VFR FLIGHT WEATHER EXPECTED DURING THE UPCOMING 24 HOUR TAF PERIOD ENDING 25/12Z. HOWEVER...EARLY IN PERIOD THROUGH 18Z... EXPECT SOME MARGINAL FLIGHT CONDITIONS FROM DEEP EAST TEXAS INTO NORTH LOUISIANA DUE TO SCATTERED CONVECTION. CIGS AREA WIDE THIS MORNING WILL RUN AROUND 5 KFT...HOWEVER IN THE CONVECTIVE AREA EXPECT OCCASIONAL CIGS 1 TO 3 KFT WITH VSBYS 3 TO 5 MI IN RAIN AND FOG. ALSO...POCKETS OF TURBULENCE COULD BE AN ISSUE FROM ISOLATED TSTMS. AFTER 18Z...CLEAR SKIES SHOULD RETURN TO MOST OF EAST TEXAS...SOUTHEAST OKLAHOMA AND ADJACENT SOUTHWEST ARKANSAS WITH IMPROVING CIGS FARTHER EAST BY 25/00Z. /14/ && .PRELIMINARY POINT TEMPS/POPS... SHV 92 62 91 65 92 / 10 10 10 10 10 MLU 89 63 89 64 91 / 30 10 10 10 10 DEQ 87 58 88 59 90 / 10 10 10 10 10 TXK 89 61 87 62 89 / 10 10 10 10 10 ELD 89 60 88 61 89 / 20 10 10 10 10 TYR 90 61 90 64 93 / 10 10 10 10 10 GGG 91 59 89 62 92 / 10 10 10 10 10 LFK 93 62 92 63 94 / 10 10 10 10 10 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...NONE. LA...NONE. OK...NONE. TX...NONE. && $$ 24/05
AREA FORECAST DISCUSSION...UPDATED
NWS BALTIMORE MD/WASHINGTON DC
939 PM EDT WED SEP 25 2013 .SYNOPSIS... AN UPPER LOW FROM THE OHIO VALLEY WILL MOVE THROUGH THE MID- ATLANTIC STATES TONIGHT. SURFACE HIGH PRESSURE BUILDS IN THURSDAY THROUGH THE WEEKEND WHILE A STORM SYSTEM DEVELOPS OFF THE COAST. A COLD FRONT WILL PASS THROUGH THE REGION EARLY NEXT WEEK. && .NEAR TERM /THROUGH THURSDAY/... AN AIRMASS CHANGE AFTER THE LAST FEW DAYS OF SOLID HIGH PRESSURE AND DRY/SEASONAL WX. AN UPPER LOW SWINGING OVER THE AREA FROM THE OHIO VLY WILL CONTINUE ON TOWARD THE COAST OVERNIGHT...W/ LITTLE MORE THAN SOME SCATTERED SHOWERS OVER THE SWRN PORTIONS OF THE CWA AND BATCHES OF CIRRUS FOR THE REST OF THE AREA. ONLY A FEW AREAS OF PRECIP WRAPPED AROUND THE UPPER LOW AND MAINLY ACROSS THE SOUTHEAST QUADRANT OF THE LOW. THE BULK OF THIS ACTIVITY SLIDING ACROSS THE CAROLINAS AND INTO CNTRL/SRN VA. THE WEAK SFC LOW DRIFTING OVER SRN WV INTO SRN VA WILL CAUSE THE PRECIP BATCH OUR OUR SWRN ZONES TO PIVOT SOUTH OF THE KCHO AREA AND CONTINUE ON TOWARD THE VA TIDEWATER INTO OVERNIGHT. HRRR SHOWING A SMALL SLICE OF THIS ACTIVITY PIVOTING ALSO OVER PARTS OF THE N CNTRL AV PIEDMONT - ORANGE/SPOTSV/CULPR/KG COS. THE REMAINDER OF CWA WILL BE DRY W/ ONLY PASSING CIRRUS AND SOME MID CLOUD DECKS. THIS WILL KEEP MUCH OF THE FOG FROM THE PREV COUPLE OF NIGHTS FROM DEVELOPING OTHER THAN A FEW TYPICAL FOG- PRONE AREAS OF THE POTOMAC HIGHLAND VLYS AND POTOMAC RVR VLY WHERE CLOUDS MAY CLEAR OUT EARLIER. MODIFIED AN INCREASE SOME POCKETS OF THE MIN T GRID...ESPEC OVER THE MTNS WHERE THE OVERHEAD CLOUD DECKS WILL MODERATE SOME OF THE LOWER TEMPS SEEN OVER THE PAST COUPLE NIGHTS. && .SHORT TERM /THURSDAY NIGHT/... THE UPPER LOW WILL BE NEAR KRIC THU MRNG. HI CLOUDS WILL CLEAR FROM NW TO SE THU MRNG BEHIND THE EXITING LOW. FCST SOUNDINGS LOOK MORE FAVORABLE FOR DEVELOPMENT OF A DIURNAL CU FIELD THAN IN RECENT DAYS. LGT NELY WINDS WITH MAX TEMPS IN 70S. HIGHS NEAR 80F POSSIBLE WITH THE WARMER URBAN HEAT ISLAND IN DC AND BALTIMORE. SFC HIPRES BUILDS IN THU NGT. THE PRESSURE SURGE LOOKS RATHER WEAK...SO BOUNDARY LAYER DECOUPLING IN SHELTERED VLYS WITH FOG DEVELOPMENT LIKELY. MIN TEMPS RANGE FROM THE UPPER 30S ON THE WEST SIDE OF THE ALLEGHENY FRONT TO UPPER 50S IN THE CITIES AND NEAR THE BAY. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... AN UPPER-LEVEL RIDGE WILL BUILD OVERHEAD FRIDAY AND SATURDAY AND A SURFACE RIDGE WILL ALSO REMAIN OVERHEAD FROM HIGH PRESSURE OVER NEW ENGLAND. THE SUBSIDENCE FROM THESE SYSTEMS WILL CAUSE MORE DRY AND SEASONABLE CONDITIONS. A BKN STRATOCU DECK MAY REMAIN OVER THE AREA FRIDAY DUE TO MOISTURE FROM A NORTHEAST FLOW OFF THE OCEAN. A COLD FRONT WILL APPROACH THE AREA SUNDAY...BUT DRY CONDITIONS WILL PERSIST. THE COLD FRONT WILL MOVE THROUGH THE AREA EARLY NEXT WEEK. A FEW SHOWERS ARE POSSIBLE...BUT ANY PRECIPITATION WILL BE LIGHT SINCE LITTLE MOISTURE WILL BE ASSOCIATED WITH THE BOUNDARY. HIGH PRESSURE WILL RETURN FOR THE MIDDLE OF NEXT WEEK. LOW PRESSURE WILL DEVELOP WELL OFF THE MID-ATLANTIC COAST THIS WEEKEND AND IT IS EXPECTED TO TRACK NORTHWARD LATER SUNDAY INTO EARLY NEXT WEEK. LATEST GUIDANCE CONTINUES TO KEEP THIS SYSTEM OUT TO SEA...BUT THIS WILL HAVE TO BE MONITORED CLOSELY OVER THE NEXT FEW DAYS. SHOULD THE SYSTEM TRACK FURTHER WEST CLOSER TO THE COAST...THEN THIS WILL HAVE A SIGNIFICANT IMPACT ON THE FORECAST SUNDAY INTO EARLY NEXT WEEK. && .AVIATION /01Z THURSDAY THROUGH MONDAY/... HI CLOUDS OVER THE AREA PROVIDES CAUSE FOR UNCERTAINTY WITH EXTENT OF FOG DEVELOPMENT...LEANING TOWARD VFR VSBYS OVERNIGHT FOR KCHO AND KMRB OVERNIGHT. OTHERWISE VFR THRU THU WITH MAINLY HI CLOUDS. AN ISO SPRINKLE POSSIBLE IN VC OF CHO THIS EVE. LGT N-NE FLOW 5 KT OR LESS THRU TNGT. SCT CU FIELD AROUND 5 KFT THU AFTN. VFR CONDITIONS ARE EXPECTED MOST OF THE TIME THU NGT THROUGH THE WEEKEND. HOWEVER...AREAS OF FOG/BR ARE EXPECTED DURING THE EARLY MORNING HOURS EACH DAY. THIS MAY RESULT IN PERIODS OF MVFR/IFR VSBYS. && .MARINE... GENERALLY NELY WINDS UNDER 10 KT THRU THU NGT WITH HIPRES IN CONTROL. THE PASSAGE OF AN UPPER LOW WILL PROVIDE LITTLE IMPACT TO BOATERS. HIGH PRESSURE WILL REMAIN OVER THE WATERS FRI THROUGH THE WEEKEND. LOW PRESSURE WILL DEVELOP OVER THE ATLANTIC THIS WEEKEND. THIS SYSTEM SHOULD REMAIN OUT TO SEA...BUT IT WILL HAVE TO BE MONITORED CLOSELY OVER THE NEXT SEVERAL DAYS. SCA WIND GUSTS ARE POSSIBLE FRIDAY THROUGH THE WEEKEND SHOULD IT TRACK CLOSER TO THE COAST THAN EXPECTED. A COLD FRONT WILL PASS THROUGH THE WATERS EARLY NEXT WEEK. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ UPDATE...GMS PREV DISCUSSION...JRK/BJL
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
200 PM EDT TUE SEP 24 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 336 AM EDT TUE SEP 24 2013 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW AN UPR RDG OVER THE GREAT LKS BTWN A CLOSED LO OVER THE CNDN MARITIMES AND A LARGER SCALE TROF OFF THE W COAST. SFC HI PRES UNDER THE SLOWLY BLDG UPR RDG IN THE GREAT LKS EXTENDS FM QUEBEC SWWD TO NEAR THE SAULT. WITH THE LARGER SCALE SUBSIDENCE AND BONE DRY MID LVLS ABV THE SUBSIDENCE INVRN SHOWN AT H9 ON THE 00Z GRB RAOB...SKIES ARE CURRENTLY MOCLR. ALTHOUGH A LLVL SE FLOW IS PRESENT OVER NRN LK MI ON THE WRN FLANK OF THE SFC RDG AXIS LIKE YESTERDAY MRNG...THERE IS SO FAR NO LO CLD SHOWING UP OVER NRN LK MI DUE TO PRESENCE OF WARMER/DRIER AIR BLO A LOWER INVRN BASE THAN WAS PRESENT 24 HRS AGO. SFC TEMPS HAVE STILL DIPPED AS LO AS THE 30S AT SOME OF THE COLD SPOTS OVER THE INTERIOR SCENTRAL AND E UNDER A FLATTER PRES GRADIENT CLOSER TO THE RDG AXIS. A SHARPER PRES GRADIENT/STRONGER SW FLOW IS RESTRICTING THE DIURNAL TEMP DROP OVER THE W AND NCENTRAL NEAR LK SUP. LOOKING FARTHER TO THE W...A FAIRLY VIGOROUS NEGATIVELY TILTED SHRTWV IS PRESENT OVER THE CENTRAL PLAINS AND LIFTING ENEWD E OF THE WRN TROF. PCPN AND EVEN MUCH IN THE WAY OF CLDS IN ADVANCE OF THIS FEATURE AND ACCOMPANYING SFC LO IN NEBRASKA ARE LIMITED BY VERY DRY AIR SHOWN ON NEARBY 00Z RAOBS. MAIN FCST CONCERNS IN THE SHORT TERM ARE POTENTIAL LO CLDS NEAR LK MI AND TEMPS. WITH CLOSED LO SPINNING OVER THE CNDN MARITIMES...THE PATTERN WL REMAIN NEARLY STAGNANT THRU TNGT. WITH THE UPR RDG REMAINING NEARLY STNRY OVER THE GREAT LKS...SHRTWV MOVING E THRU THE PLAINS IS PROGGED TO WEAKEN AND PASS WELL TO THE S OF UPR MI AND HAVE NO IMPACT ON THE CWA. TODAY...ALTHOUGH NO CLDS HAVE FORMED AS OF 06Z...SOME OF THE SHORTER TERM MODELS HINT SOME LK EFFECT LO CLDS WL FORM OVER NRN LK MI AND THE SE CWA THRU SUNRISE AIDED BY NOCTURNAL COOLING OF SHALLOW SUB INVRN LYR. ON THE OTHER HAND...SOME OF THE HIER RESOLUTION GUIDANCE THAT HAS HAD A GOOD TRACK RECORD WITH THIS LO CLD IN RECENT DAYS... SPECIFICALLY THE 00Z LOCAL WRF-ARW MODEL AND SOME RAPID UPDATE MODELS...SHOW LIMITED LK EFFECT LO CLDS. GIVEN THE WARMER TEMPS OBSVD AT THE INVRN BASE...SUSPECT FOG RELATED TO RADIATION COOLING OVER LAND WL BE MORE LIKELY AT LEAST OVER THE INTERIOR SCENTRAL AND E. SO ADDED SOME FOG/LO CLD IN THIS AREA INTO MID MRNG. WITH LOWER SUN ANGLE...SOME LO CLD MIGHT LINGER INTO EARLY AFTN BEFORE BURNING OFF. OVER THE W...ABUNDANT SUNSHINE IN THE PRESENCE OF H85 TEMPS NEAR 12Z WL BOOST MAX TEMPS INTO THE 70S AWAY FM THE INFLUENCE OF LK SUP IN LLVL E-SE FLOW. AREAS OVER THE E AND SCENTRAL WL BE COOLER... ESPECIALLY IF ANY LO CLDS THAT FORM ARE MORE EXTENSIVE AND LINGER LONGER. TNGT...WITH A WEAKER PRES GRADIENT TNGT AS THE SFC HI PRES RDG EXPANDS A BIT TO THE W AND MID LVL DRY AIR/PWAT NEAR 0.50 INCH LINGERING...TENDED TOWARD THE LO END OF GUIDANCE FOR MIN TEMPS UNDER MOCLR SKIES. EXPECT SOME FOG TO DVLP UNDER THESE CONDITIONS WITH LENGTHENING DARKNESS. THERE MAY ALSO BE SOME FROST AT SOME OF THE INTERIOR COLDER LOCATIONS... BUT THE EXPECTED COVERAGE SHOULD NOT BE ENUF TO JUSTIFY A FROST ADVY. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 336 AM EDT TUE SEP 24 2013 THE SECOND HALF OF THE WORK WEEK WILL SEE THE AREA REMAINING UNDER THE INFLUENCE OF THE UPPER RIDGE OVER THE GREAT LAKES AND ONTARIO AND A SURFACE HIGH STATIONED OVER EASTERN ONTARIO AND WESTERN QUEBEC. THIS SETUP WILL CONTINUE WARM AND DRY CONDITIONS OVER THE U.P. THROUGH FRIDAY. WILL CONTINUE THE MOSTLY SUNNY IDEA FOR THE FORECAST WITH HIGHS IN THE UPPER 60S AND LOWER 70S EACH DAY. FOR THE WEEKEND...THE UPPER TROUGH CURRENTLY APPROACHING THE PACIFIC NORTHWEST WILL BEGIN TO MOVE OUT OF THE ROCKIES ON FRIDAY AND THROUGH THE UPPER GREAT LAKES REGION THIS WEEKEND. LATEST GFS/CANADIAN RUNS HAVE TRENDED TOWARDS THE SLOWER ECMWF RUN AND WILL CONTINUE TO TREND THE POP FORECASTS TOWARDS THAT SLOWER SOLUTION. THAT SEEMS REASONABLE WITH THE STRONG RIDGE OVER OUR AREA AND THE SLOW TO EXIT LOW DEPARTING THE CANADIAN MARITIMES. NOW INSTEAD OF THE FRONT AND UPPER TROUGH MOVING THROUGH FRIDAY NIGHT AND SATURDAY (AS SHOWN THE LAST COUPLE OF NIGHTS)...THEY LOOK TO MOVE ACROSS THE AREA SATURDAY NIGHT INTO SUNDAY. THERE COULD STILL BE SOME SHOWERS OVER WESTERN LAKE SUPERIOR AND POTENTIALLY WESTERN UPPER MICHIGAN FRIDAY NIGHT INTO SATURDAY...ASSOCIATED WITH AN AREA OF FGEN ALONG THE ELONGATED SURFACE TROUGH THAT IS SETUP OVER THE MN ARROWHEAD. THUS...WILL KEEP AT LEAST SOME SLIGHT CHANCE POPS OVER THE WESTERN THIRD OF THE CWA FOR FRIDAY NIGHT INTO SATURDAY BEFORE TRANSITIONING IT ACROSS THE REST OF THE CWA. WITH THE LATEST TRENDS...THERE COULD BE A DECENT SOAKING RAIN FOR THE WESTERN CWA DUE TO SLOW EASTWARD MOVEMENT AND SOUTHWESTERLY FLOW AHEAD OF THE TROUGH. THAT AREA HAS BEEN DRY THIS MONTH...SO IT WILL BE MUCH NEEDED. FINALLY...OPTED TO REMOVE THUNDER FROM ALL BUT FAR WESTERN LAKE SUPERIOR (FRIDAY AFTERNOON/EVENING) AS SHOWALTERS CONTINUE TO LOOK MARGINAL WITH VERY LIMITED MUCAPE VALUES (LESS THAN 150 J/KG). MODELS DIFFERENCES GROW HEADING INTO NEXT WEEK...AS THE ECMWF/CANADIAN CONTINUE TO REINFORCE THE UPPER TROUGH IN THE UPPER GREAT LAKES. MEANWHILE...THE 18Z GFS WAS VERY PROGRESSIVE AND THE 00Z GFS IS HALFWAY BETWEEN THE PREVIOUS RUN AND THE ECMWF/CANADIAN/GFS-ENS. LATE ARRIVING 00Z ECMWF HAS MOVED IN A SLIGHTLY DIFFERENT DIRECTION...WITH WEAK RIDGING BEFORE ANOTHER WAVE ON TUESDAY. THUS...WILL JUST GO WITH A SILENT 20 POP. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON) ISSUED AT 159 PM EDT TUE SEP 24 2013 VFR CONDITIONS ARE EXPECTED INTO THIS EVENING AT ALL SITES AS HIGH PRESSURE REMAINS IN CONTROL. THE MAIN CONCERN IN THIS PERIOD WILL BE FOG DEVELOPMENT AT SAW...AND POSSIBLY CMX OVERNIGHT. IWD SHOULD REMAIN VFR WITH LIGHT DOWNSLOPING S WINDS. PERSISTENT CONDITIONS FROM LAST NIGHT INTO TONIGHT AND CALM WINDS UNDER HIGH PRESSURE WILL LEAD TO RADIATIONAL FOG DEVELOPMENT ACROSS CENTRAL UPPER MI OVERNIGHT. LIGHT SE UPSLOPE FLOW WILL ALSO ASSIST DEVELOPMENT AT SAW. CURRENTLY HAVE SAW FORECAST TO REACH THE LIFR-VLIFR THRESHOLD LATE TONIGHT INTO WEDNESDAY MORNING...THOUGH WOULD NOT BE SURPRISED IF VLIFR/LANDING MIN CONDITIONS ARE OBSERVED FOR SEVERAL HOURS BEFORE 12Z. AS FOR CMX...SOME BRIEF GROUND FOG DEVELOPMENT MAY BEGIN VERY LATE TONIGHT AS WAS SEEN EARLY THIS MORNING...BUT EXPECTATION IS THAT MVFR CONDITIONS TO POSSIBLY IFR CONDITIONS WILL OCCUR. FOG/LOW STRATUS TOOK A BIT OF TIME TO MIX OUT THIS MORNING...AND DO NOT SEE WHY THAT WILL NOT BE THE CASE WEDNESDAY MORNING. HAVE INTRODUCED A SLOW IMPROVING TREND AT SAW THROUGH 18Z. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 336 AM EDT TUE SEP 24 2013 WITH RELATIVELY WEAK PRES GRADIENT OVER THE UPPER GREAT LAKES... EXPECT WINDS INTO FRI TO REMAIN UNDER 20 KTS. THE APPROACH OF A COLD FRONT TOWARD SAT AND SHARPENING PRES GRADIENT MAY LEAD TO A BIT STRONGER S WINDS UP TO 20-25 KTS. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...KC LONG TERM...SRF AVIATION...KLUBER MARINE...KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
729 AM EDT TUE SEP 24 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 336 AM EDT TUE SEP 24 2013 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW AN UPR RDG OVER THE GREAT LKS BTWN A CLOSED LO OVER THE CNDN MARITIMES AND A LARGER SCALE TROF OFF THE W COAST. SFC HI PRES UNDER THE SLOWLY BLDG UPR RDG IN THE GREAT LKS EXTENDS FM QUEBEC SWWD TO NEAR THE SAULT. WITH THE LARGER SCALE SUBSIDENCE AND BONE DRY MID LVLS ABV THE SUBSIDENCE INVRN SHOWN AT H9 ON THE 00Z GRB RAOB...SKIES ARE CURRENTLY MOCLR. ALTHOUGH A LLVL SE FLOW IS PRESENT OVER NRN LK MI ON THE WRN FLANK OF THE SFC RDG AXIS LIKE YESTERDAY MRNG...THERE IS SO FAR NO LO CLD SHOWING UP OVER NRN LK MI DUE TO PRESENCE OF WARMER/DRIER AIR BLO A LOWER INVRN BASE THAN WAS PRESENT 24 HRS AGO. SFC TEMPS HAVE STILL DIPPED AS LO AS THE 30S AT SOME OF THE COLD SPOTS OVER THE INTERIOR SCENTRAL AND E UNDER A FLATTER PRES GRADIENT CLOSER TO THE RDG AXIS. A SHARPER PRES GRADIENT/STRONGER SW FLOW IS RESTRICTING THE DIURNAL TEMP DROP OVER THE W AND NCENTRAL NEAR LK SUP. LOOKING FARTHER TO THE W...A FAIRLY VIGOROUS NEGATIVELY TILTED SHRTWV IS PRESENT OVER THE CENTRAL PLAINS AND LIFTING ENEWD E OF THE WRN TROF. PCPN AND EVEN MUCH IN THE WAY OF CLDS IN ADVANCE OF THIS FEATURE AND ACCOMPANYING SFC LO IN NEBRASKA ARE LIMITED BY VERY DRY AIR SHOWN ON NEARBY 00Z RAOBS. MAIN FCST CONCERNS IN THE SHORT TERM ARE POTENTIAL LO CLDS NEAR LK MI AND TEMPS. WITH CLOSED LO SPINNING OVER THE CNDN MARITIMES...THE PATTERN WL REMAIN NEARLY STAGNANT THRU TNGT. WITH THE UPR RDG REMAINING NEARLY STNRY OVER THE GREAT LKS...SHRTWV MOVING E THRU THE PLAINS IS PROGGED TO WEAKEN AND PASS WELL TO THE S OF UPR MI AND HAVE NO IMPACT ON THE CWA. TODAY...ALTHOUGH NO CLDS HAVE FORMED AS OF 06Z...SOME OF THE SHORTER TERM MODELS HINT SOME LK EFFECT LO CLDS WL FORM OVER NRN LK MI AND THE SE CWA THRU SUNRISE AIDED BY NOCTURNAL COOLING OF SHALLOW SUB INVRN LYR. ON THE OTHER HAND...SOME OF THE HIER RESOLUTION GUIDANCE THAT HAS HAD A GOOD TRACK RECORD WITH THIS LO CLD IN RECENT DAYS... SPECIFICALLY THE 00Z LOCAL WRF-ARW MODEL AND SOME RAPID UPDATE MODELS...SHOW LIMITED LK EFFECT LO CLDS. GIVEN THE WARMER TEMPS OBSVD AT THE INVRN BASE...SUSPECT FOG RELATED TO RADIATION COOLING OVER LAND WL BE MORE LIKELY AT LEAST OVER THE INTERIOR SCENTRAL AND E. SO ADDED SOME FOG/LO CLD IN THIS AREA INTO MID MRNG. WITH LOWER SUN ANGLE...SOME LO CLD MIGHT LINGER INTO EARLY AFTN BEFORE BURNING OFF. OVER THE W...ABUNDANT SUNSHINE IN THE PRESENCE OF H85 TEMPS NEAR 12Z WL BOOST MAX TEMPS INTO THE 70S AWAY FM THE INFLUENCE OF LK SUP IN LLVL E-SE FLOW. AREAS OVER THE E AND SCENTRAL WL BE COOLER... ESPECIALLY IF ANY LO CLDS THAT FORM ARE MORE EXTENSIVE AND LINGER LONGER. TNGT...WITH A WEAKER PRES GRADIENT TNGT AS THE SFC HI PRES RDG EXPANDS A BIT TO THE W AND MID LVL DRY AIR/PWAT NEAR 0.50 INCH LINGERING...TENDED TOWARD THE LO END OF GUIDANCE FOR MIN TEMPS UNDER MOCLR SKIES. EXPECT SOME FOG TO DVLP UNDER THESE CONDITIONS WITH LENGTHENING DARKNESS. THERE MAY ALSO BE SOME FROST AT SOME OF THE INTERIOR COLDER LOCATIONS... BUT THE EXPECTED COVERAGE SHOULD NOT BE ENUF TO JUSTIFY A FROST ADVY. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 336 AM EDT TUE SEP 24 2013 THE SECOND HALF OF THE WORK WEEK WILL SEE THE AREA REMAINING UNDER THE INFLUENCE OF THE UPPER RIDGE OVER THE GREAT LAKES AND ONTARIO AND A SURFACE HIGH STATIONED OVER EASTERN ONTARIO AND WESTERN QUEBEC. THIS SETUP WILL CONTINUE WARM AND DRY CONDITIONS OVER THE U.P. THROUGH FRIDAY. WILL CONTINUE THE MOSTLY SUNNY IDEA FOR THE FORECAST WITH HIGHS IN THE UPPER 60S AND LOWER 70S EACH DAY. FOR THE WEEKEND...THE UPPER TROUGH CURRENTLY APPROACHING THE PACIFIC NORTHWEST WILL BEGIN TO MOVE OUT OF THE ROCKIES ON FRIDAY AND THROUGH THE UPPER GREAT LAKES REGION THIS WEEKEND. LATEST GFS/CANADIAN RUNS HAVE TRENDED TOWARDS THE SLOWER ECMWF RUN AND WILL CONTINUE TO TREND THE POP FORECASTS TOWARDS THAT SLOWER SOLUTION. THAT SEEMS REASONABLE WITH THE STRONG RIDGE OVER OUR AREA AND THE SLOW TO EXIT LOW DEPARTING THE CANADIAN MARITIMES. NOW INSTEAD OF THE FRONT AND UPPER TROUGH MOVING THROUGH FRIDAY NIGHT AND SATURDAY (AS SHOWN THE LAST COUPLE OF NIGHTS)...THEY LOOK TO MOVE ACROSS THE AREA SATURDAY NIGHT INTO SUNDAY. THERE COULD STILL BE SOME SHOWERS OVER WESTERN LAKE SUPERIOR AND POTENTIALLY WESTERN UPPER MICHIGAN FRIDAY NIGHT INTO SATURDAY...ASSOCIATED WITH AN AREA OF FGEN ALONG THE ELONGATED SURFACE TROUGH THAT IS SETUP OVER THE MN ARROWHEAD. THUS...WILL KEEP AT LEAST SOME SLIGHT CHANCE POPS OVER THE WESTERN THIRD OF THE CWA FOR FRIDAY NIGHT INTO SATURDAY BEFORE TRANSITIONING IT ACROSS THE REST OF THE CWA. WITH THE LATEST TRENDS...THERE COULD BE A DECENT SOAKING RAIN FOR THE WESTERN CWA DUE TO SLOW EASTWARD MOVEMENT AND SOUTHWESTERLY FLOW AHEAD OF THE TROUGH. THAT AREA HAS BEEN DRY THIS MONTH...SO IT WILL BE MUCH NEEDED. FINALLY...OPTED TO REMOVE THUNDER FROM ALL BUT FAR WESTERN LAKE SUPERIOR (FRIDAY AFTERNOON/EVENING) AS SHOWALTERS CONTINUE TO LOOK MARGINAL WITH VERY LIMITED MUCAPE VALUES (LESS THAN 150 J/KG). MODELS DIFFERENCES GROW HEADING INTO NEXT WEEK...AS THE ECMWF/CANADIAN CONTINUE TO REINFORCE THE UPPER TROUGH IN THE UPPER GREAT LAKES. MEANWHILE...THE 18Z GFS WAS VERY PROGRESSIVE AND THE 00Z GFS IS HALFWAY BETWEEN THE PREVIOUS RUN AND THE ECMWF/CANADIAN/GFS-ENS. LATE ARRIVING 00Z ECMWF HAS MOVED IN A SLIGHTLY DIFFERENT DIRECTION...WITH WEAK RIDGING BEFORE ANOTHER WAVE ON TUESDAY. THUS...WILL JUST GO WITH A SILENT 20 POP. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING) ISSUED AT 728 AM EDT TUE SEP 24 2013 LO CLDS THIS MRNG AT SAW ASSOCIATED WITH AN UPSLOPE SSE FLOW ARND STNRY HI PRES IN SE CANADA WL SLOWLY DSPT BY THIS AFTN WITH DAYTIME HEATING/MIXING. SINCE IWD/CMX ARE DOMINATED BY A DOWNSLOPE S WIND COMPONENT...THESE LOCATIONS WL EXPERIENCE VFR CONDITIONS THRU THE DAY. MORE FOG/IFR CONDITIONS WL DVLP AT SAW TNGT WITH MOCLR SKIES/ LGT WINDS AS SFC HI PRES EXPANDS WWD BACK INTO THE UPR LKS. SOME FOG MAY ALSO IMPACT CMX...BUT A BIT STRONGER S WIND EXPECTED AT IWD SHOULD KEEP THAT LOCATION FOG FREE. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 336 AM EDT TUE SEP 24 2013 WITH RELATIVELY WEAK PRES GRADIENT OVER THE UPPER GREAT LAKES... EXPECT WINDS INTO FRI TO REMAIN UNDER 20 KTS. THE APPROACH OF A COLD FRONT TOWARD SAT AND SHARPENING PRES GRADIENT MAY LEAD TO A BIT STRONGER S WINDS UP TO 20-25 KTS. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...KC LONG TERM...SRF AVIATION...KC MARINE...KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
337 AM EDT TUE SEP 24 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 336 AM EDT TUE SEP 24 2013 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW AN UPR RDG OVER THE GREAT LKS BTWN A CLOSED LO OVER THE CNDN MARITIMES AND A LARGER SCALE TROF OFF THE W COAST. SFC HI PRES UNDER THE SLOWLY BLDG UPR RDG IN THE GREAT LKS EXTENDS FM QUEBEC SWWD TO NEAR THE SAULT. WITH THE LARGER SCALE SUBSIDENCE AND BONE DRY MID LVLS ABV THE SUBSIDENCE INVRN SHOWN AT H9 ON THE 00Z GRB RAOB...SKIES ARE CURRENTLY MOCLR. ALTHOUGH A LLVL SE FLOW IS PRESENT OVER NRN LK MI ON THE WRN FLANK OF THE SFC RDG AXIS LIKE YESTERDAY MRNG...THERE IS SO FAR NO LO CLD SHOWING UP OVER NRN LK MI DUE TO PRESENCE OF WARMER/DRIER AIR BLO A LOWER INVRN BASE THAN WAS PRESENT 24 HRS AGO. SFC TEMPS HAVE STILL DIPPED AS LO AS THE 30S AT SOME OF THE COLD SPOTS OVER THE INTERIOR SCENTRAL AND E UNDER A FLATTER PRES GRADIENT CLOSER TO THE RDG AXIS. A SHARPER PRES GRADIENT/STRONGER SW FLOW IS RESTRICTING THE DIURNAL TEMP DROP OVER THE W AND NCENTRAL NEAR LK SUP. LOOKING FARTHER TO THE W...A FAIRLY VIGOROUS NEGATIVELY TILTED SHRTWV IS PRESENT OVER THE CENTRAL PLAINS AND LIFTING ENEWD E OF THE WRN TROF. PCPN AND EVEN MUCH IN THE WAY OF CLDS IN ADVANCE OF THIS FEATURE AND ACCOMPANYING SFC LO IN NEBRASKA ARE LIMITED BY VERY DRY AIR SHOWN ON NEARBY 00Z RAOBS. MAIN FCST CONCERNS IN THE SHORT TERM ARE POTENTIAL LO CLDS NEAR LK MI AND TEMPS. WITH CLOSED LO SPINNING OVER THE CNDN MARITIMES...THE PATTERN WL REMAIN NEARLY STAGNANT THRU TNGT. WITH THE UPR RDG REMAINING NEARLY STNRY OVER THE GREAT LKS...SHRTWV MOVING E THRU THE PLAINS IS PROGGED TO WEAKEN AND PASS WELL TO THE S OF UPR MI AND HAVE NO IMPACT ON THE CWA. TODAY...ALTHOUGH NO CLDS HAVE FORMED AS OF 06Z...SOME OF THE SHORTER TERM MODELS HINT SOME LK EFFECT LO CLDS WL FORM OVER NRN LK MI AND THE SE CWA THRU SUNRISE AIDED BY NOCTURNAL COOLING OF SHALLOW SUB INVRN LYR. ON THE OTHER HAND...SOME OF THE HIER RESOLUTION GUIDANCE THAT HAS HAD A GOOD TRACK RECORD WITH THIS LO CLD IN RECENT DAYS... SPECIFICALLY THE 00Z LOCAL WRF-ARW MODEL AND SOME RAPID UPDATE MODELS...SHOW LIMITED LK EFFECT LO CLDS. GIVEN THE WARMER TEMPS OBSVD AT THE INVRN BASE...SUSPECT FOG RELATED TO RADIATION COOLING OVER LAND WL BE MORE LIKELY AT LEAST OVER THE INTERIOR SCENTRAL AND E. SO ADDED SOME FOG/LO CLD IN THIS AREA INTO MID MRNG. WITH LOWER SUN ANGLE...SOME LO CLD MIGHT LINGER INTO EARLY AFTN BEFORE BURNING OFF. OVER THE W...ABUNDANT SUNSHINE IN THE PRESENCE OF H85 TEMPS NEAR 12Z WL BOOST MAX TEMPS INTO THE 70S AWAY FM THE INFLUENCE OF LK SUP IN LLVL E-SE FLOW. AREAS OVER THE E AND SCENTRAL WL BE COOLER... ESPECIALLY IF ANY LO CLDS THAT FORM ARE MORE EXTENSIVE AND LINGER LONGER. TNGT...WITH A WEAKER PRES GRADIENT TNGT AS THE SFC HI PRES RDG EXPANDS A BIT TO THE W AND MID LVL DRY AIR/PWAT NEAR 0.50 INCH LINGERING...TENDED TOWARD THE LO END OF GUIDANCE FOR MIN TEMPS UNDER MOCLR SKIES. EXPECT SOME FOG TO DVLP UNDER THESE CONDITIONS WITH LENGTHENING DARKNESS. THERE MAY ALSO BE SOME FROST AT SOME OF THE INTERIOR COLDER LOCATIONS... BUT THE EXPECTED COVERAGE SHOULD NOT BE ENUF TO JUSTIFY A FROST ADVY. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 336 AM EDT TUE SEP 24 2013 THE SECOND HALF OF THE WORK WEEK WILL SEE THE AREA REMAINING UNDER THE INFLUENCE OF THE UPPER RIDGE OVER THE GREAT LAKES AND ONTARIO AND A SURFACE HIGH STATIONED OVER EASTERN ONTARIO AND WESTERN QUEBEC. THIS SETUP WILL CONTINUE WARM AND DRY CONDITIONS OVER THE U.P. THROUGH FRIDAY. WILL CONTINUE THE MOSTLY SUNNY IDEA FOR THE FORECAST WITH HIGHS IN THE UPPER 60S AND LOWER 70S EACH DAY. FOR THE WEEKEND...THE UPPER TROUGH CURRENTLY APPROACHING THE PACIFIC NORTHWEST WILL BEGIN TO MOVE OUT OF THE ROCKIES ON FRIDAY AND THROUGH THE UPPER GREAT LAKES REGION THIS WEEKEND. LATEST GFS/CANADIAN RUNS HAVE TRENDED TOWARDS THE SLOWER ECMWF RUN AND WILL CONTINUE TO TREND THE POP FORECASTS TOWARDS THAT SLOWER SOLUTION. THAT SEEMS REASONABLE WITH THE STRONG RIDGE OVER OUR AREA AND THE SLOW TO EXIT LOW DEPARTING THE CANADIAN MARITIMES. NOW INSTEAD OF THE FRONT AND UPPER TROUGH MOVING THROUGH FRIDAY NIGHT AND SATURDAY (AS SHOWN THE LAST COUPLE OF NIGHTS)...THEY LOOK TO MOVE ACROSS THE AREA SATURDAY NIGHT INTO SUNDAY. THERE COULD STILL BE SOME SHOWERS OVER WESTERN LAKE SUPERIOR AND POTENTIALLY WESTERN UPPER MICHIGAN FRIDAY NIGHT INTO SATURDAY...ASSOCIATED WITH AN AREA OF FGEN ALONG THE ELONGATED SURFACE TROUGH THAT IS SETUP OVER THE MN ARROWHEAD. THUS...WILL KEEP AT LEAST SOME SLIGHT CHANCE POPS OVER THE WESTERN THIRD OF THE CWA FOR FRIDAY NIGHT INTO SATURDAY BEFORE TRANSITIONING IT ACROSS THE REST OF THE CWA. WITH THE LATEST TRENDS...THERE COULD BE A DECENT SOAKING RAIN FOR THE WESTERN CWA DUE TO SLOW EASTWARD MOVEMENT AND SOUTHWESTERLY FLOW AHEAD OF THE TROUGH. THAT AREA HAS BEEN DRY THIS MONTH...SO IT WILL BE MUCH NEEDED. FINALLY...OPTED TO REMOVE THUNDER FROM ALL BUT FAR WESTERN LAKE SUPERIOR (FRIDAY AFTERNOON/EVENING) AS SHOWALTERS CONTINUE TO LOOK MARGINAL WITH VERY LIMITED MUCAPE VALUES (LESS THAN 150 J/KG). MODELS DIFFERENCES GROW HEADING INTO NEXT WEEK...AS THE ECMWF/CANADIAN CONTINUE TO REINFORCE THE UPPER TROUGH IN THE UPPER GREAT LAKES. MEANWHILE...THE 18Z GFS WAS VERY PROGRESSIVE AND THE 00Z GFS IS HALFWAY BETWEEN THE PREVIOUS RUN AND THE ECMWF/CANADIAN/GFS-ENS. LATE ARRIVING 00Z ECMWF HAS MOVED IN A SLIGHTLY DIFFERENT DIRECTION...WITH WEAK RIDGING BEFORE ANOTHER WAVE ON TUESDAY. THUS...WILL JUST GO WITH A SILENT 20 POP. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT) ISSUED AT 130 AM EDT TUE SEP 24 2013 VFR CONDITIONS SHOULD PREVAIL AT KIWD/KCMX/KSAW THRU THIS FCST PERIOD UNDER A GENERALLY DRY AIR MASS ASSOCIATED WITH HIGH PRES OVER ONTARIO/WRN QUEBEC. AT THIS POINT...NOT ANTICIPATING LOW CLOUDS TO FORM AT KSAW LATE TONIGHT UNDER SSE UPSLOPE FLOW OFF LAKE MICHIGAN SINCE CURRENT DWPTS OVER NRN LAKE MICHIGAN AREN`T SIGNIFICANTLY HIGHER THAN FORECAST MIN TEMPS OVERNIGHT. COULD SEE AN EASTERLY LAKE BREEZE DEVELOP MID TUE AFTERNOON AT KCMX WITH SFC RDG NOSING IN FROM THE EAST. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 336 AM EDT TUE SEP 24 2013 WITH RELATIVELY WEAK PRES GRADIENT OVER THE UPPER GREAT LAKES... EXPECT WINDS INTO FRI TO REMAIN UNDER 20 KTS. THE APPROACH OF A COLD FRONT TOWARD SAT AND SHARPENING PRES GRADIENT MAY LEAD TO A BIT STRONGER S WINDS UP TO 20-25 KTS. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...KC LONG TERM...SRF AVIATION...VOSS MARINE...KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
130 AM EDT TUE SEP 24 2013 .SHORT TERM...(THIS EVENING THROUGH TUESDAY) ISSUED AT 405 PM EDT MON SEP 23 2013 WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A MID LEVEL RIDGE OVER THE WRN GREAT LAKES. UPSTREAM...A WELL-DEFINED MID LEVEL LOW WAS LIFTING NE THRU WRN NEBRASKA. ALTHOUGH THE SFC HIGH PRES RIDGE IS EAST OF THE AREA...EXTENDING FROM JAMES BAY TO LAKE HURON...STUBBORN STRATOCU REMAINS DOWNWIND OF LAKE MICHIGAN...THOUGH THERE ARE SIGNS THAT COVERAGE IS STARTING TO SHRINK DUE TO A COMBINATION OF FALLING INVERSION HEIGHTS (PER RAOBS TRENDS) AND DAYTIME HEATING MIXING OUT LOW-LEVEL MOISTURE. WARMING AIR MASS IS ALSO DIMINISHING THE LAKE COMPONENT TO CLOUD COVER. ABUNDANT SUNSHINE HAS HELPED TO RAISE TEMPS INTO MID 60S THIS AFTN OVER THE W HALF OF UPPER MI. ALTHOUGH A WELL-DEFINED SHORTWAVE IS OVER THE WRN PLAINS...SHORT TERM AND THE NEXT SEVERAL DAYS WILL BE QUIET WEATHER WISE. MAIN FCST CONCERN WILL BE CLOUD COVER. WITH STRATOCU COVERAGE NEAR LAKE MICHIGAN SHOWING SIGNS OF SHRINKING...THERE IS HOPE THAT THE CLOUDS WILL CONTINUE TO DISSIPATE AND NOT REDEVELOP/EXPAND TONIGHT... ESPECIALLY SINCE INVERSION BASE TEMPS OVER NRN LAKE MICHIGAN WILL BE A COUPLE OF C HIGHER TONIGHT THAN LAST NIGHT. HOWEVER...SINCE TRAJECTORIES LEAD SSE BACK TO THE STRATOCU/MOISTURE FIELD OVER SRN LWR MI/NRN OH...STRATOCU PROBABLY WON`T CLEAR OUT FOR THE ENTIRE NIGHT. THERE MAY BE A PERIOD THIS EVENING WHEN MUCH OF THE CLOUD COVER DISSIPATES...BUT EXPECT SOME INCREASE IN STRATOCU AGAIN OVERNIGHT GIVEN UPSTREAM CLOUD COVER/MOISTURE AS MENTIONED AND DUE TO LAND BREEZE CONVERGENCE DEVELOPING OVER LAKE MICHIGAN. CLOUDS SHOULDN`T BE AS EXTENSIVE LATE TONIGHT/TUE MORNING AS EARLIER TODAY. AS FOR TEMPS...GENERALLY FAVORED THE LOW END OF GUIDANCE WITH PRECIPITABLE WATER 50-60PCT OF NORMAL AND WEAKER PRES GRADIENT/LOW-LEVEL WINDS LATER TONIGHT THAN EARLY THIS MORNING. WITH MINS DOWN INTO THE MID 30S IN THE INTERIOR...EXPECT PATCHY FROST OVERNIGHT. MODELS ARE IN GOOD AGREEMENT TAKING THE CURRENTLY WELL-DEFINED MID LOW OVER NEBRASKA E INTO THE MID MISSISSIPPI VALLEY TUE AND WEAKENING IT AS IT CUTS INTO THE MID LEVEL RIDGE. FEATURE WILL HAVE NO AFFECT ON THE WEATHER HERE TUE AS DRY AIR LINGERS OVER THE AREA. AS WITH TONIGHT...MAIN CONCERN TUE WILL BE STRATOCU NEAR LAKE MI. STRATOCU DOWNWIND OF THE LAKE MAY BRIEFLY EXPAND WESTWARD FOR A COUPLE OF HRS TUE MORNING AS DAYTIME HEATING WORKS ON LOW-LEVEL MOISTURE...BUT THERE SHOULD BE A SOMEWHAT QUICKER EROSION OF THE CLOUDS FROM INLAND TOWARD THE LAKE THAN TODAY. OTHER THAN THE CLOUD ISSUE...TUE IS SHAPING UP TO BE A NICE AUTUMN DAY. IF MIXING REACHES 850MB...MAX TEMPS IN THE LOW/MID 70S WOULD BE COMMON. MIXING DEPTH MAY NOT GET QUITE THAT HIGH...SO UPPER 60S/LWR 70S LOOK MORE LIKELY AWAY FROM MARINE INFLUENCE. .LONG TERM...(TUESDAY NIGHT THROUGH MONDAY) ISSUED AT 249 PM EDT MON SEP 23 2013 WILL START THE PERIOD AT 00Z WEDNESDAY WITH THE 500MB RIDGE STILL SET UP ACROSS E UPPER MI AND LAKE HURON/E ONTARIO. THE MAIN STORY WILL BE THE CONTINUALLY WEAKENING TROUGH STRETCHING FROM MN THROUGH NW TN. A HIGHLY BROKEN LINE OF SHOWERS MAY BE SET UP ACROSS MN...BUT WITH THE WEAKENING OF THE TROUGH AND SFC HIGH WITH LIGHT NE FLOW AT THE SFC...LITTLE MORE THAN CLOUDS ARE ANTICIPATED ACROSS UPPER MI LATE TUESDAY NIGHT INTO WEDNESDAY MORNING. BEHIND THE 500MB TROUGH...THE S-CENTRAL PLAINS RIDGE WILL QUICKLY BUILD BACK ACROSS THE UPPER GREAT LAKES WEDNESDAY THROUGH THURSDAY. LOOK FOR STRONGER SW FLOW TO TAKE OVER ALOFT AT AT THE SFC THURSDAY NIGHT THROUGH FRIDAY NIGHT...AHEAD OF THE NEARING TROUGH TO OUT W. COOLER AIRMASS IS ON THE WAY FOR THE WEEKEND. WE CAN GET A GLIMPSE OF WHAT IS TO COME BY LOOKING AT THE 00Z SATURDAY 850MB TEMPS ACROSS THE REGION. 850MB TEMPS WILL LIKELY RANGE FROM 14-16Z ACROSS UPPER MI...WHILE A MUCH COOLER 4-6C ACROSS NW ND. ONLY MINIMAL TS POTENTIAL ALONG THE FRONT...GIVEN ITS NOCTURNAL PASSAGE OVER THE W CWA SATURDAY MORNING. THERE ARE ENOUGH SIGNIFICANT DIFFERENCES BETWEEN THE ECMWF AND GFS AT THIS POINT TO GO WITH A CONSENSUS SOLUTION. THE 23/12Z RUN OF THE GFS IS AROUND 6HRS FASTER THAN THE 23/00Z ECMWF WITH THE PASSAGE OF THE SHORTWAVE. STILL...THEY ARE STARTING TO COME TO A BETTER AGREEMENT WHEN COMPARED TO THE MUCH QUICKER 23/06Z RUN OF THE GFS. THE ENTIRE SYSTEM LOOKS TO MODERATE QUITE A BIT...WITH THE COOLEST AIR FILTERING INTO UPPER MI BEING AROUND 5-7C SATURDAY NIGHT THROUGH MONDAY MORNING. AS AN ASIDE...THE 23/12Z RUN OF THE GFS ONLY HAS 850MB TEMPS COOLING TO AROUND 10C. MUCH OF THIS IS DUE TO THE DIFFERENCE IN THE HANDLING OF THE MID-UPPER LEVEL WAVE. THE ECMWF IS PERSISTENT IN HAVING THE TROUGH OVER THE UPPER GREAT LAKES THIS WEEKEND CUT OFF FROM THE MAIN W-E FLOW AND FORM A LOW OVERHEAD...BEFORE DROPPING IT INTO THE MID MS VALLEY THROUGH THE MIDDLE OF NEXT WEEK. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT) ISSUED AT 130 AM EDT TUE SEP 24 2013 VFR CONDITIONS SHOULD PREVAIL AT KIWD/KCMX/KSAW THRU THIS FCST PERIOD UNDER A GENERALLY DRY AIR MASS ASSOCIATED WITH HIGH PRES OVER ONTARIO/WRN QUEBEC. AT THIS POINT...NOT ANTICIPATING LOW CLOUDS TO FORM AT KSAW LATE TONIGHT UNDER SSE UPSLOPE FLOW OFF LAKE MICHIGAN SINCE CURRENT DWPTS OVER NRN LAKE MICHIGAN AREN`T SIGNIFICANTLY HIGHER THAN FORECAST MIN TEMPS OVERNIGHT. COULD SEE AN EASTERLY LAKE BREEZE DEVELOP MID TUE AFTERNOON AT KCMX WITH SFC RDG NOSING IN FROM THE EAST. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 405 PM EDT MON SEP 23 2013 SLOW MOVING WEATHER PATTERN THIS WEEK WILL FEATURE HIGH PRES TO THE E AND LOW PRES TO THE W. EVENTUALLY...A LOW PRES SYSTEM WILL MOVE NE TO HUDSON BAY LATE WEEK WITH ASSOCIATED COLD FRONT PASSING ACROSS LAKE SUPERIOR SAT. THRU THE WEEK...RELATIVELY WEAK PRES GRADIENT WILL RESULT IN WINDS MOSTLY UNDER 20KT. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...ROLFSON LONG TERM...KF AVIATION...VOSS MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS DULUTH MN
640 PM CDT WED SEP 25 2013 .SYNOPSIS... ISSUED AT 328 PM CDT WED SEP 25 2013 LAKE SUPERIOR DOMINATED BY LOW STRATUS/FOG LAYER WHILE INLAND AREAS ARE SUNNY UNDER A DRY AIR MASS AND HIGH PRESSURE. MAJOR UPPER TROF OVER INTERMOUNTAIN WEST IS AMPLIFYING COURTESY OF 140KT UPPER JET ON SWRN FLANK OF CIRCULATION. A SWRLY MID LVL FLOW IS CURRENTLY IN PLACE ACROSS THE CWA. AN AREA OF MID CLOUDS ASSOCIATED WITH A WEAK SHORTWAVE FEATURE ALOFT IS MOVING INTO THE WRN CWA. WARM ADVECTION REGIME CONTINUES TO INCREASE OVER THE CWA AS CYCLOGENESIS IS UNDERWAY OVER WRN HI PLAINS. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 328 PM CDT WED SEP 25 2013 TONIGHT...EXPECT AREA OF CLOUDS/FOG OVER LAKE SUPERIOR TO ADVECT INLAND AS SFC HEATING DECREASES. LATEST HRRR 3KM SHOWS HIGHEST PROB OF LOWEST VIS ALONG NSHORE...TWIN PORTS...AND CHEQUAMEGON BAY.WILL ISSUE A DENSE FOG ADVISORY CONSIDERING THE PRESENCE OF THE DENSE FOG OVER THE LAKE AND ITS LIKELY PENETRATION INLAND. LATEST HI-RES MDLS SUGGEST FOG BANK MAY TRY TO SHIFT FARTHER NORTH AND WEST OVERNIGHT. ELSEWHERE WILL USE PATCHY FOG FOR POTENTIAL OF LIGHT WINDS/SATURATION IN NEAR SFC LAYER. TOMORROW...DENSE FOG EXPECTED TO PERSIST NEAR LAKE SUPERIOR THROUGH EARLY MORNING. MAIN ISSUE TOMORROW WILL BE INCREASE IN GUSTY SE WINDS. LATEST BUFKIT MOMENTUM PROFILES INDICATE GUSTS TO 35 AND POSSIBLY AN ISOLATED 40 MPH ARE POSSIBLE OVER NE MN ZONES BY AFTN. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 328 PM CDT WED SEP 25 2013 ON THURSDAY NIGHT...A SHARP UPPER LEVEL RIDGE WILL EXTEND THROUGH THE CENTRAL PLAINS...INTO THE JAMES BAY AREA NEAR HUDSON BAY. MEANWHILE...A LONGWAVE TROUGH WILL BE LOCATED IN THE FAR SOUTHWESTERN UNITED STATES. IN BETWEEN WE WILL BE IN SW FLOW. THE MODELS ARE HINTING AT A LOW PRESSURE SYSTEM DEVELOPING IN THE HIGH PLAINS THURSDAY NIGHT AND FRIDAY...WITH A FRONT OR SURFACE TROUGH EXTENDING NORTHEASTWARD INTO MINNESOTA. QPF AMOUNTS VARY...BUT THE GENERAL CONSENSUS IS THAT THERE WILL BE SOME LIGHT PRECIPITATION ACROSS THE MN SIDE OF OUR CWA. THE LONGWAVE TROUGH EDGES EASTWARD ON FRIDAY...BRINGING A POTENTIALLY MORE SUBSTANTIAL CHANCE OF PRECIPITATION TO THE CWA. THE BEST CHANCE OF RAIN AND EMBEDDED THUNDERSTORMS WOULD BE IN THE MN SIDE ONCE AGAIN. A SHORTWAVE AND UPPER LEVEL VORT MAX WILL LIFT INTO THE UPPER RED RIVER VALLEY AND WESTERN GREAT LAKES REGION FRIDAY NIGHT AND SATURDAY...BRINGING A WET PERIOD TO THE WESTERN GREAT LAKES FRIDAY NIGHT AND SATURDAY. THE GFS IS FASTEST AT PUSHING THE SYSTEM OUT OF THE AREA ON SATURDAY...WITH THE GEM AND ECMWF BEING SLOWER. WILL USE A BLEND OF THE ABOVE MODELS FOR THE MOST PART. BY SUNDAY...A MORE ZONAL FLOW ESTABLISHES ITSELF ACROSS THE NORTH CENTRAL UNITED STATES. SUNDAY INTO TUESDAY LOOKS LIKE IT WILL BE GENERALLY DRY ACROSS THE REGION...WITH A CHANCE OF SHOWERS IN ONLY A FEW LOCATIONS THROUGH WEDNESDAY AS WELL. TEMPERATURES WILL GENERALLY BE ABOVE NORMAL WITH HIGHS IN THE 60S AND EVEN SOME LOWER TO MIDDLE 70S. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING) ISSUED AT 637 PM CDT WED SEP 25 2013 FOG AND STRATUS WILL BE THE MAIN ISSUES THIS TAF PERIOD. LATEST SATELLITE IMAGERY AND OBSERVATIONS REVEAL STRATUS AND FOG OVER LAKE SUPERIOR...AND RIGHT ALONG THE LAKE SHORE. THE EXCEPTION WAS AT THE HEAD OF THE LAKE WHERE STRONGER EASTERLY WINDS WERE PUSHING THE STRATUS/FOG INTO EASTERN CARLTON COUNTY. WITH LOSS OF HEATING THIS EVENING...WE DO EXPECT THE FOG/STRATUS TO PUSH FURTHER INLAND...ESPECIALLY FROM THE HEAD OF THE LAKE UP THE NORTH SHORE. OVERALL...THE MEAN LOW LEVEL FLOW WILL VEER TO MORE SOUTHEAST OVERNIGHT. THIS MAY KEEP THE FOG/STRATUS FROM PENETRATING TOO FAR INLAND ALONG THE SOUTH SHORE OR CAUSE IT TO RETREAT NORTH LATE. GUSTY SOUTHEASTERLY WINDS ON THURSDAY WILL CAUSE THE FOG/STRATUS TO LIFT FOR MOST AREAS...HOLDING ON ALONG THE NORTH SHORE THE LONGEST. WINDS WILL GUST FROM 25 TO 30 MPH AT TIMES. && .PRELIMINARY POINT TEMPS/POPS... DLH 49 72 56 75 / 0 0 10 10 INL 50 75 57 69 / 0 0 10 70 BRD 53 81 61 72 / 0 0 10 40 HYR 46 74 57 79 / 0 0 0 10 ASX 46 72 57 78 / 0 0 0 10 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...DENSE FOG ADVISORY UNTIL 9 AM CDT THURSDAY FOR MNZ020-021-037. WI...DENSE FOG ADVISORY UNTIL 9 AM CDT THURSDAY FOR WIZ001>004. LS...DENSE FOG ADVISORY UNTIL NOON CDT THURSDAY FOR LSZ121-140>148. && $$ SYNOPSIS...CANNON SHORT TERM...CANNON LONG TERM...DAP AVIATION...MELDE
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
234 PM CDT Tue Sep 24 2013 .SHORT TERM...(This Evening through Wednesday Night) Issued at 231 PM CDT TUE SEP 24 2013 Relatively tranquil weather will prevail through much of the next 36 hours, with the one potential exception this afternoon. As of early this afternoon, a surface low pressure center in the process of occluding was analyzed near Kansas City, moving east-southeastward. The shortwave trough aloft was nearly vertically stacked, with the H85-H5 within 150 miles of the occluding surface low. Visible satellite imagery has shown a gradual increase in low-level cumulus, with clearing persistent ahead of the surface low. A narrow corridor of weak instability has begun to develop within a southeast to northwest arc. Short-term model guidance has shown a forecasted increase in 0-3km CAPE of up to 200-400J/Kg by late afternoon over northeast portions of the EAX forecast area. While the forecasted instability is modest at best, this in combination with strong vertical ascent may promote low-topped convection to develop by mid to late afternoon. The RUC, NAM, GFS, GEM, and HRRR outputs all suggest convection to develop in northeastern sections of the CWA. With an environment characterized by sufficient instability to maintain low-topped convection, concomitant with moderate low-level (sfc-H85) directional wind shear and moderate surface vorticity, the potential exists for a transient funnel cloud or two underneath persistent updraft bases later this afternoon in any mature convection that develops. The probability for this to occur is relatively low, and any chance a vortex would reach the surface is very low. Overall coverage of lightning occurrence should be low as well due to the low-topped nature anticipated with the convection. Much of this forecasted activity is expected to wane shortly after sunset with the loss of diurnal instability. Otherwise, as the shortwave trough shifts east of the area tonight, an upper ridge will build into the central CONUS on Wednesday. A notable increase in high temperatures is expected tomorrow afternoon with highs reaching the upper 70s to lower 80s under mostly clear skies. .LONG TERM...(Thursday through Tuesday) Issued at 231 PM CDT TUE SEP 24 2013 For the later periods of the forecast, lovely late summer/early fall conditions will dominate, though some thunderstorms might put a damper on the beginning of the weekend. As Thursday dawns, an amplified pattern will be in place across the nation, with a large western CONUS trough juxtaposed against building eastern CONUS ridge. This will leave our section of the country under rather benign regime for Thursday and Friday. Models advertise 850mb temperatures in the mid-teens late in the work week, leaving expectations that highs will range in the 80s. These above seasonally average temperatures late in the work week will be occurring ahead of a frontal passage expected to occur Saturday. Over the weekend the western CONUS trough will be filling and lifting through the Plains States. The resulting frontal passage is currently advertised to occur in our section of Kansas and Missouri during the daylight hours of Saturday. Models are in decent agreement on the evolution of the trough and timing of the associated frontal passage, though given the jet streak noted diving under the trough as it lifts out thoughts are that the eventual timing will slow, leaving the frontal passage through our forecast area lingering into the overnight hours of Saturday. Expectations are that convection along the front will start Friday night across areas from central Kansas into eastern Nebraska. These storms will likely spread into eastern Kansas and far western Missouri towards sunrise Saturday morning. Slow progress of the front might keep storms percolating across western Missouri through much of the day, while also slowly spreading east with the front. Have kept fairly expansive likely POPs in place for Saturday night owing to low confidence that the front will have completely cleared the forecast area before nightfall. Otherwise, beyond Saturday`s potential stormy weather, the remainder of the weekend and into next work week (Sunday through Tuesday) looks rather beautiful. Temperatures are currently expected to range between highs in the 70s and lows in the 50s as a quasi-zonal upper level pattern moves into the Plains in the wake of the exiting trough. && .AVIATION...(For the 18Z TAFS through 18Z Wednesday Afternoon) Issued at 1202 PM CDT TUE SEP 24 2013 Tricky ceiling forecast this afternoon/evening for terminals as center of surface low passes nearby. Expect mainly high-end MVFR or low-end VFR ceiling heights through early evening before cloud coverage decreases and heights increase. As for precipitation, expect TAF sites to remain dry. Winds will be somewhat variable as surface flow veers with time. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...NONE. MO...NONE. && $$ SHORT TERM...Blair LONG TERM...Cutter AVIATION...Blair
AREA FORECAST DISCUSSION
NWS GLASGOW MT
827 PM MDT WED SEP 25 2013 .SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH FRIDAY... EVENING UPDATE... FORECAST LOOKS TO BE IN GREAT SHAPE. NO CHANGES ARE ANTICIPATED FOR THIS EVENING. RAIN SHOWERS HAS STRUNG OUT ACROSS THE EASTERN HALF OF THE CWA AND SHOULD CLEAR FROM WEST TO EAST. CLOUD COVER WILL BE OVERCAST TONIGHT WHICH WILL KEEP TEMPERATURES UP AND LOWS A LITTLE WARMER THAN USUAL. GAH PREVIOUS SHORT TERM DISCUSSION... WITH THE RAIN EVENT NOW UNDERWAY ACROSS NORTHEAST MONTANA...SHORT TERM MODEL SOLUTIONS HAVE MORE OR LESS CONGEALED AROUND A FAIRLY GOOD CONSENSUS OVER THE LAST FEW MODEL RUNS. FORECAST CHALLENGES WILL FOCUS MAINLY ON THE TIMING...INTENSITY...AND AMOUNT OF PRECIPITATION RESULTING FROM THIS RAIN STORM. MOST OF THE DAY TODAY...AND LITTLE BIT TONIGHT...THE NARROW LINEAR BAND OF RAIN MOVING THROUGH OUR CENTRAL ZONE FROM SSW TO NNE HAS BEEN AND WILL CONTINUE TO BE THE DOMINANT FEATURE. THIS HAS BEEN WELL REPRESENTED BY THE MODELS WITH THE GFS AND THE HRRR BEING THE MOST ACCURATE. EXPECT MOST OF THE REMAINING CWA TO FILL IN WITH AT LEAST A WETTING RAIN OVER THE NEXT 24 HOURS AS A PINCHED OFF LOBE CENTER FROM THE DEEP UPPER LEVEL TROUGH MOVES RIGHT OVER OUR CWA. EXPECT MOST PRECIPITATION AMOUNTS FOR THE STORM TO BE BETWEEN 0.20 AND 0.60. WINDS FILTERING IN THE BACKSIDE OF THIS SYSTEM FROM THE NORTHWEST WILL BE STRONG ENOUGH TO JUSTIFY A LAKE WIND ADVISORY FROM THURSDAY MORNING THROUGH LATE THURSDAY NIGHT...WHICH HAS BEEN ISSUED. SHOULD BEGIN IN THE 15G25KT RANGE...INCREASE TO NEAR THE 20G30KT RANGE DURING THE AFTERNOON AND DIMINISH AGAIN INTO THE 15G25KT RANGE AFTER SUNSET. BY OVERNIGHT THURSDAY NIGHT TO EARLY FRIDAY MORNING...EMBEDDED WITHIN THE LARGER SCALE TROUGH...A SHORT WAVE RIDGE WILL TEMPORARILY BRING A LULL IN THE RAIN FOR A GOOD PART OF OUR CWA. THEN...AS THE MAIN TROUGH AXIS PASSES OVER EASTERN MONTANA...A BAND OF RAIN WILL LINE UP AND GLANCE OUR SOUTHEASTERN ZONES THROUGHOUT THE REMAINDER OF THE FORECAST PERIOD. TEMPERATURES WILL BE QUITE COOL...BUT NOT COLD ENOUGH TO RESULT IN ANY MIXED PRECIPITATION. BMICKELSON .LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY... GOING FORECAST IN GOOD SHAPE. THE MEDIUM RANGE MODELS WERE IN BETTER AGREEMENT WITH NEXT WEEK BRINGING IN ANOTHER TROUGH FROM THE PACIFIC NORTHWEST. MODELS...IN PARTICULAR THE ECMWF...ARE MORE PROGRESSIVE. A GENERAL DRY PATTERN WITH A COOLER AIRMASS ARRIVAL TUESDAY LOOKS GOOD. NO CHANGES. TFJ PREVIOUS DISCUSSION... SYNOPTIC SET UP... A LARGE RIDGE RUNS FROM THE SOUTHERN PLAINS... THROUGH THE UPPER MISSISSIPPI VALLEY... AND INTO THE HUDSON BAY. AN EQUALLY LARGE TROUGH RUNS FROM THE FOUR CORNERS THROUGH EASTERN MONTANA AND THE NORTHWEST TERRITORIES WITH A STRONG COLD FRONT RIGHT BETWEEN THE TWO LARGE FEATURES. TO THE WEST... A WEAK RIDGE RUNS UP THE US WEST COAST WITH A TROUGH SPINNING OVER THE GULF OF ALASKA AND ARCTIC COLD AIR CHURNING RIGHT BEHIND IT OVER THE BEARING SEA. FRIDAY NIGHT THOUGH SUNDAY NIGHT... THE TROUGH ALOFT AND THEN RIDGE TO THE WEST PASS THROUGH THE AREA. BUT WITH MINIMAL MOISTURE TO PLAY WITH... CONDITIONS WILL REMAIN DRY WITH A SLIGHT WARMING TREND. MONDAY TO TUESDAY... THE GULF OF ALASKA TROUGH WILL PUSH OVER BRITISH COLUMBIA AND BE AIDED BY A JET ROUNDING ITS PERIPHERY WHICH SHOULD BRING A CLIPPER STYLE SHORTWAVE AND COLD FRONT THROUGH THE AREA OVER A 12 HOUR PERIOD IN THIS TIME FRAME. MODELS ARE HAVING SOME TROUBLE ON TIMING BECAUSE IT RELIES ON THE SMALL PERTURBATION OF A JET/WAVE OVER THE BEARING SEA STARTING ALL THE WAY BACK AT FRIDAY NIGHT AND AMPLIFYING AS IT ROUNDS THE BC TROUGH. THE 00Z RUN OF GFS AND EC APPEAR TO LINE UP AROUND LATE MONDAY AFTERNOON. BUT... THIS COULD QUICKLY CHANGE. POPS ARE POSSIBLE DURING THIS PERIOD. BUT... DUE TO THE CLIPPER NATURE WOULD BE VERY SHORT WITH LIGHT QPF. TUESDAY NIGHT THROUGH WEDNESDAY NIGHT... MODELS ARE STRUGGLING HERE. A ZONAL TO WEAK TROUGH PATTERN IS ANTICIPATED AND THIS TYPICALLY MEANS SLIGHTLY BELOW SEASONAL TEMPS. THEREFORE... TRENDED TEMPS DOWN DURING THIS TIME. GAH && .AVIATION... VFR WITH PERIODS OF MVFR. RAIN AND LOW CEILINGS WILL CONTINUE TO MOVE INTO THE AREA THIS EVENING. CONDITIONS ARE EXPECTED TO GRADUALLY IMPROVE LATE THURSDAY. NORTHWEST WINDS WILL INCREASE TONIGHT WITH SPEEDS OF AROUND 15 KTS. SPEEDS ARE EXPECTED TO INCREASE TO 20 KTS THURSDAY WITH GUSTS TO ABOUT 30 KTS. TFJ/PROTON && .GLASGOW WATCHES/WARNINGS/ADVISORIES... LAKE WIND ADVISORY FROM 7 AM THURSDAY TO MIDNIGHT MDT THURSDAY NIGHT FOR FORT PECK LAKE FOR CENTRAL AND SOUTHEAST PHILLIPS... CENTRAL AND SOUTHERN VALLEY...GARFIELD...MCCONE...PETROLEUM. && $$ WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1254 PM CDT TUE SEP 24 2013 .UPDATE... ISSUED AT 904 AM CDT TUE SEP 24 2013 LOW LEVEL STRATUS WILL BE SLOW TO CLEAR ACROSS THE AREA THIS MORNING...WITH A FEW BREAKS ALREADY EVIDENT ACROSS THE WESTERN FRINGES OF THE CWA. EXPECT THIS STRATUS TO CLEAR FROM WEST TO EAST THROUGH THE AFTERNOON...WITH SOME PATCHY DRIZZLE POSSIBLE ACROSS NORTHEASTERN AREAS THROUGH ABOUT NOON. OTHER THAN INCREASING CLOUD COVER AND ADDING SOME PATCHY DRIZZLE PER REPORTS FROM AROUND THE REGION...NO OTHER CHANGES NECESSARY TO THE INHERITED FORECAST AS TEMPERATURES LOOK ON TRACK AND A MOSTLY SUNNY AFTERNOON WILL EVENTUALLY EMERGE ACROSS MOST...IF NOT ALL...OF THE LOCAL FORECAST AREA. UPDATE ISSUED AT 700 AM CDT TUE SEP 24 2013 AS DISCUSSED IN GREATER DETAIL IN THE PRIMARY OVERNIGHT DISCUSSION...LOW STRATUS TRENDS CONTINUE TO BE A HEADACHE. ALTHOUGH A FEW CORRIDORS OF CLEARING REMAIN...MUCH OF THE CWA IS NOW UNDER FAIRLY WIDESPREAD LOW CLOUDS...WITH THE HRRR SUGGESTING THAT GENERALLY THE EASTERN 3/4 OF THE CWA COULD REMAIN FAIRLY SOCKED IN THROUGH MID-DAY. AS A RESULT...YET AGAIN BUMPED UP SKY COVER PERCENTAGES AND SLOWED THE RATE OF WEST-TO-EAST CLEARING...BUT STILL THINKING THAT MOST AREAS SHOULD AVERAGE NO WORSE THAN PARTLY CLOUDY THROUGH THE BALANCE OF THE AFTERNOON. WILL STAY THE COURSE WITH PREVIOUS HIGH TEMPS FOR NOW...AS ANY CLEARING SHOULD RESULT IN A QUICK RISE AND HELP OFFSET ANY POTENTIAL DELAY IN WARMING FROM MORNING CLOUD COVER. ON ONE FINAL NOTE...RADAR TRENDS SUPPORTED KILLING THE SLIGHT POPS THAT ORIGINALLY LINGERED IN A FEW FAR NORTHEAST COUNTIES THROUGH 15Z/10AM...SO NOW THE FORECAST IS OFFICIALLY VOID OF ALL PRECIP MENTION UNTIL THURS NIGHT. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 438 AM CDT TUE SEP 24 2013 ALTHOUGH MOST IF NOT ALL OF THE CWA IS LOOKING AT A DRY AND FAIRLY UNEVENTFUL UPCOMING 24 HOURS...ESPECIALLY THE DAYTIME HOURS HAVE BECOME TRICKIER-THAN-EXPECTED MAINLY REGARDING THE EVOLUTION OF SKY COVER/TEMPERATURES...AS LOW CLOUDS COULD BE STUBBORNLY SLOW TO DEPART MAINLY WITHIN THE EASTERN 1/2 OF THE CWA...BRINGING 5+ DEGREE TEMP BUST POTENTIAL VERY MUCH INTO PLAY. 08Z OBJECTIVE SURFACE ANALYSIS HIGHLIGHTS A SLOWLY-WEAKENING 1004 MILLIBAR LOW PRESSURE CENTER...CENTERED OVER THE CLAY/FILLMORE COUNTY AREA...WHILE IN ITS WAKE THE LEADING EDGES OF HIGH PRESSURE AROUND 1016MB HAS WORKED INTO THE NEB PANHANDLE. WITH THE MAJORITY OF THE CWA POSITIONED BEHIND THE DEPARTING LOW...EARLY MORNING BREEZES ARE MAINLY FROM THE WEST-NORTHWEST...WITH THE STRONGEST SPEEDS WITH GUSTS OF 20+ MPH FOCUSED ACROSS THE SOUTHWESTERN HALF OF THE AREA...WITH LIGHTER SPEEDS STILL HOLDING ON FOR AT LEAST A FEW MORE HOURS WITHIN MUCH OF THE NORTHEAST 1/2. ALOFT...WATER VAPOR IMAGERY AND SHORT TERM MODEL DATA CLEARLY REVEAL A WELL- DEFINED...NOT QUITE VERTICALLY STACKED LOW PRESSURE SYSTEM DEPARTING EASTWARD ACROSS THE EASTERN 1/4 OF NEB...WITH A CLOSED 500MB CIRCULATION CENTERED NEAR NORFOLK. AS A RESULT...THE PRIMARY MID LEVEL CONVERGENCE/DEFORMATION ZONE AT THIS HOUR IS FOCUSING WIDESPREAD MAINLY LIGHT RAIN 50+ MILES NORTHEAST OF THE CWA. CLOUD-WISE...11-3.9 MICRON SATELLITE IMAGERY DEPICTS A FAIRLY COMPLEX AND EVER-CHANGING MIXTURE OF CLEAR SKIES ALONG WITH PASSING BATCHES OF MID CLOUDS AND LOW STRATUS. WHILE MOST OF THESE LOWER CEILINGS WITHIN THE CWA ARE AT/ABOVE 1500 FT...A CORRIDOR OF LOWER CEILINGS BETWEEN 500-1000 FT SEEMS TO BE LURKING JUST NORTHWEST OF THE CWA ALONG A BROKEN BOW-AINSWORTH AXIS...WITH THESE LOW CLOUDS POSSIBLY EVEN SUPPORTING SOME PATCHY LIGHT DRIZZLE. TEMP-WISE...MOST OF THE CWA APPEARS HEADED FOR OVERNIGHT LOWS IN THE MID 50S...WITH ANY LOW 50S/UPPER 40S MOST FAVORED IN FAR WESTERN COUNTIES. AS THE EARLY MORNING/DAYTIME HOURS WEAR ON...THE BIG PICTURE ALOFT INVOLVES THE MID LEVEL SHORTWAVE TROUGH/ASSOCIATED CLOSED LOW CONTINUING ITS STEADY TREK EASTWARD...WITH THE 500MB CIRCULATION CENTER INTO SOUTHWEST IA BY 18Z...AND THEN OVER NORTH CENTRAL MO BY 00Z/7PM. AS THIS LOW DEPARTS...A BROAD AREA OF SHORTWAVE RIDGING AND ASSOCIATED HEIGHT RISES WILL OVERSPREAD THE CENTRAL PLAINS. AT THE SURFACE...THE LOW PRESSURE CENTER CURRENTLY OVER SOUTHEAST NEB WILL CONTINUE TO WEAKEN AS IT SLIDES INTO CENTRAL MO OVER THE COURSE OF THE DAY...ALLOWING A MODEST RIDGE AXIS TO BUILD INTO THE LOCAL AREA WITH TIME AND RELAX THE SURFACE PRESSURE GRADIENT. HOWEVER...BREEZES WILL STILL BE FAIRLY ELEVATED FOR MUCH OF THE DAY TODAY...LARGELY OWING TO MIXING CLIMBING UP TO AROUND 850MB...WHERE AN ENHANCED CORRIDOR OF 30-40KT NORTHERLY WINDS WILL LINGER THROUGH MID-DAY BEFORE STEADILY WEAKENING IN THE AFTERNOON. THE NET RESULT WILL BE SUSTAINED NORTH-NORTHWEST WIND SPEEDS 15-20 MPH WITH GUSTS 25+ MPH THROUGH THIS MORNING...BEFORE DIMINISHING TO MORE SO SUSTAINED 10-15 MPH SPEEDS THIS AFTERNOON...AND ONLY 5-10 MPH CLOSER TO SUNSET. AS FOR PRECIP CHANCES...ALTHOUGH RADAR TRENDS AND SHORT TERM MODEL DATA INCLUDING THE HRRR PRETTY STRONGLY SUGGEST THAN ANY RISK OF MEASURABLE LIGHT RAIN SHOULD BE OVER BY 12Z...WENT AHEAD AND LINGERED A TOKEN 20 POP IN THE EXTREME NORTHEAST NANCE/MERRICK/POLK AREA THROUGH 15Z IN CASE SOMETHING MANAGES TO STILL WRAP AROUND THE BACK SIDE OF THE LOW. THE BIG CHALLENGE TODAY SEEMS TO BE CENTERED AROUND SKY COVER. 24 HOURS AGO...IT WAS ASSUMED THAT MID LEVEL CLOUDS WOULD QUICKLY MOVE OFF EAST OF THE CWA TODAY WITH THE PARENT SYSTEM. HOWEVER...LATEST SATELLITE AND SHORT TERM MODEL DATA INCLUDING THE HRRR LOW CLOUD PRODUCT NOW SUGGEST THAT THE AREAL COVERAGE OF LOW STRATUS MAY IN FACT INCREASE BEFORE SUNRISE FROM THE NORTHWEST...AND THEN POSSIBLY HANG VERY STUBBORNLY MAINLY ACROSS THE CENTRAL/EASTERN CWA EVEN INTO THE AFTERNOON HOURS. ALTHOUGH HAVE NOT BOUGHT FULL-BORE INTO THE VERY PESSIMISTIC RUC/HRRR SOLUTIONS REGARDING LOW CLOUDS TODAY...DID INCREASE SKY COVER PERCENTAGES VERSUS PREVIOUS...AND ALSO DELAYED THE WEST-EAST CLEARING TREND. HOWEVER...PLEASE NOTE THAT ESPECIALLY EASTERN COUNTIES ALONG/NEAR HIGHWAY 81 MAY REALLY STRUGGLE TO SEE MUCH SUN UNTIL MAYBE LATE AFTERNOON...AND DAY SHIFT MAY HAVE TO MAKE SOME PRETTY NOTICEABLE ADJUSTMENTS TO SKY COVER AND RESULTANT HIGH TEMPS. FOR NOW THOUGH...OPTED TO ONLY SHAVE 1-2 DEGREES OFF PREVIOUS HIGHS IN MOST AREAS...RANGING FROM LOW 70S FAR EAST TO UPPER 70S FAR SOUTHWEST...AND AROUND 73 TRI- CITIES. IF CLOUDS ARE SLOW TO DEPART HOWEVER...SOME EASTERN AREAS MAY STRUGGLE TO LEAVE THE 60S. ON ONE FINAL DAYTIME NOTE...ALTHOUGH HAVE DEWPOINTS DROPPING INTO THE LOW-MID 40S ACROSS MUCH OF THE WESTERN CWA DURING THE AFTERNOON...THESE VALUES ARE NOT QUITE AS LOW AS ANTICIPATED 24 HOURS AGO...AND THIS KEEPS ANY AFTERNOON RELATIVE HUMIDITY VALUES AS LOW AS 25-30 PERCENT CONFINED TO MAINLY JUST THE FURNAS COUNTY AREA. FOR THE EVENING/NIGHT 00Z-12Z PERIOD...WILL RUN WITH THE ASSUMPTION THAT EVEN IF LOW STRATUS LINGERS QUITE AWHILE INTO THE AFTERNOON IN SOME AREAS...THAT IT SHOULD BE SAFELY EAST OF THE CWA BY SUNSET...THUS RESULTING IN A CLEAR OVERNIGHT AREA-WIDE WITH ESSENTIALLY ZERO RISK OF PRECIP. ON THE BIG PICTURE...THE HEART OF THE AFOREMENTIONED MID/UPPER LEVEL SHORTWAVE RIDGE AXIS WILL PASS DIRECTLY OVER THE CWA...VERY SIMILAR TO LAST FRIDAY NIGHT. ALSO SIMILAR TO LAST FRIDAY AT THE SURFACE...VERY LIGHT/VARIABLE BREEZES IN THE EVENING WILL GRADUALLY GIVE WAY TO LIGHT SOUTHEAST BREEZES LATER IN THE NIGHT AS THE SURFACE RIDGE AXIS DRIFTS EASTWARD ACROSS THE CWA. HOWEVER...COMPARED TO 24 HOURS AGO IT NOW APPEARS THAT DEWPOINTS WILL NOT DROP OFF QUITE AS FAR...AND THUS GUIDANCE/MODELS HAVE TRENDED A FEW DEGREES MILDER FOR OVERNIGHT LOWS. AS A RESULT...NUDGED UP LOWS 1-2 DEGREES MOST AREAS VERSUS PREVIOUS...AIMING MOST OF THE CWA BETWEEN 50-53...BUT WITH PREDOMINANTLY MID-UPPER 40S IN A FEW OF THE FAR WESTERN NORTHERN/COUNTIES. DESPITE THE LIGHT OVERNIGHT BREEZES...AM NOT EXPECTING IMPACTFUL FOG TO BE AN ISSUE...ALTHOUGH SOME VERY LIGHT FOG/HAZE IS PROBABLY NOT OUT OF THE QUESTION...BUT IS ALSO NOT WORTH ADVERTISING IN THE FORECAST. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 438 AM CDT TUE SEP 24 2013 PATTERN: THE CPC OBSERVED H5 HGT ANOMALY TOOLS SHOW THAT THE LOW FREQUENCY /LGWV/ FLOW OF THE PAST 90 DAYS LARGELY REMAINS IN PLACE OVER THE NRN HEMISPHERE. HOWEVER...WE HAVE RECENTLY SEEN AMPLIFICATION ESPECIALLY WITH THE ERN PAC TROF. OTHER ADJUSTMENTS SHOW THAT THE +HGT ANOMALY WHICH HAS RESIDED OVER WRN N AMERICA HAS SHIFT TO THE E...ALLOWING THE TEMPORARY ESTABLISHMENT OF A WRN N AMERICA TROF. THIS TROF WILL ONLY BE WITH US THIS WEEK AND OFFERS ONE MORE SHOT AT DECENT RAINFALL. THE NAO HAS TURNED SHARPLY NEGATIVE AS THE PERSISTENT -HGT ANOMALY OVER GREENLAND HAS BEEN REPLACED WITH +HGT ANOMALIES. THIS COMBINED WITH THE A PAIR OF STORMS CROSSING THE NRN PAC WILL RETURN RIDGING TO WRN N AMERICA THIS WEEKEND. SO THE BOTTOM LINE IS...EXCEPT FOR A BRIEF WINDOW THU NGT-FRI...DRY WX WILL CONT. TEMPS WILL BE VARIABLE BUT PROBABLY AVERAGE PRETTY CLOSE TO NORMAL OVER THE NEXT 10 DAYS. ALOFT: SW FLOW WILL DEVELOP OVER THE CNTRL PLAINS WED AND CONT THRU FRI...AS THE WRN USA TROF FULLY RELOADS. CYCLOGENESIS WILL OCCUR THU...WITH THE MAIN UPR LOW HEADING N INTO CANADA. THE MAIN UPR TROF WILL BE LEFT BEHIND AND BEGIN LIFTING NE...CROSSING THE CNTRL PLAINS SAT. NW FLOW FOLLOWS SUN-MON BUT THERE IS DISAGREEMENT/UNCERTAINTY IN THE AMPLITUDE OF THE RIDGE MOVING INTO THE W. SFC: A PAC COLD FRONT WILL EXTEND FROM THE NRN ROCKIES TO CNTRL CA WED...WITH A LEE-SIDE TROF IN PLACE. THIS FRONT WILL ADVANCE E AND EMERGE ONTO THE PLAINS BY DAWN THU. HOWEVER...THE SRN PORTION WILL REMAIN STATIONARY DUE TO MINIMAL MOVEMENT OF THE BASE OF THE TROF. THE SLOW EJECTION OF THE TROF MEANS THE FWD PROGRESS OF THE FRONT WILL BE SLOW. WRN USA HIGH PRES BUILDS IN SAT THRU MON. WITH SW FLOW ALOFT ON BOTH SIDES OF THIS FRONT...IT WILL HAVE AN ANABATIC CHARACTER. THE SLOW MOVEMENT OFFERS THE OPPORTUNITY FOR ENTRAINMENT OF GULF MSTR. WE ARE SEEING A NARROW RIBBON OF MSTR FCST TO SURGE NWD FRI...WITH PW NEARING 1.6". HAZARDS: NOTHING SUBSTANTIAL...BUT THERE IS A LATE-WEEK THUNDER THREAT. RISK OF SVR LOOKS VERY LOW. THE DAILY DETAILS... WED: WARM SECTOR. BREEZY AND WARMER BY 7-10F. WED NGT: A STRONG LLJ WILL DEVELOP /55-60 KTS/ WITH LOW-LVL WINDS VEERING TO THE SW. THIS WILL ADVECT AN EML ONTO THE PLAINS... IMPOSING A SUBSTANTIAL CAP. THU: WARM SECTOR. VERY WARM. ADD ANOTHER 3-7F TO WED AND THIS WILL PUT HIGHS 10F ABOVE NORMAL. HIGHS IN THE LWR 90S LOOK LIKE A GOOD BET OVER N-CNTRL KS. THU NGT: SOME ISOLATED HIGH-BASED SHWRS/TSTMS ARE POSSIBLE. THIS REALLY DEPENDS ON WHERE THE LLJ CORE SETS UP. THE EC IS FURTHER N THAN THE GFS AND NAM. IF SHWRS/TSTMS DEVELOP RAINFALL AMTS WILL BE VERY LIGHT. FRI: WARM SECTOR...BUT THE FRONT THREATENS THE NW FRINGE OF THE FCST AREA DURING PEAK HEATING. MOST OF THE FCST AREA SHOULD REMAIN DRY FOR MOST OF THE DAY. PCPN AND CLOUDS WILL BE MOST EXTENSIVE BEHIND THE FRONT WHICH SHOULD RESULT IN A SUBSTANTIAL TEMP CONTRAST ACROSS THE STATE. AHEAD OF THE FRONT EXPECT THE ATMS TO BE CAPPED. SCT TSTMS SHOULD ONLY ERUPT IN THE IMMEDIATE VICINITY OF THE FRONT IN THE LATE AFTN. SEVERE?: PROBABLY NOT BUT IF THERE IS A THREAT IS LOOKS VERY MARGINAL DUE TO WEAK INSTABILITY. HOWEVER...STRENGTH OF THE WIND FIELDS AND THE DRY SUB-CLOUD LAYER COULD SUPPORT SOME DECENT WINDS IF A STRONGER STORM OR TWO CAN DEVELOP. FRI NGT: COLD FRONTAL PASSAGE. THE SETUP LOOKS GOOD FOR SOME DECENT POST-FRONTAL RAINFALL IN SOME LOCATIONS. SAT: MUCH COOLER! PROBABLY 20F COOLER THAN FRI. IN FACT...WITH THE UPR TROF MOVING THRU...BELIEVE FUTURE FCSTS WILL END UP LOWERING HIGHS ANOTHER 5F OR SO. CONSENSUS OF 2M TEMPS CURRENTLY OFFERS 57F AT ORD AND 67F AT BELOIT. NOT MUCH DIFF FROM THE 12Z/18Z CYCLES. SWEATSHIRTS AND JACKETS MAY BE NEEDED FOR OUTDOOR ACTIVITIES. CLOUDY TO START WITH A COUPLE LEFTOVER SHWRS OR SOME PATCHY DRZL. CLEARING PROGRESSES FROM W TO E IN THE AFTN. SUN-MON: BACK TO NICER WX. TEMPS REBOUND AND WITH LOW PRES MOVING THRU THE CANADIAN ROCKIES...A LEE-SIDE TROF WILL DEVELOP AND MAY ACTUALLY PROGRESS THRU THE FCST AREA WITH AN ATTENDANT THERMAL RIDGE. HIGHS SHOULD BE BACK INTO THE LOW-MID 70S SUN AND UPR 70S-80 MON? && .AVIATION...(FOR THE 18Z KGRI TAF THROUGH 18Z WEDNESDAY AFTERNOON) ISSUED AT 1240 PM CDT TUE SEP 24 2013 PREVAILING VFR CONDITIONS ARE EXPECTED AT KGRI FOR THE NEXT 24 HOURS...ALBEIT A BRIEF MVFR CIG WILL REMAIN POSSIBLE THROUGH ABOUT 20Z. THEREAFTER...WINDS WILL BE THE PRIMARY FOCUS AS GENERALLY CLEAR SKIES ARE EXPECTED TO PREVAIL AS A WEAK RIDGE OF HIGH PRESSURE BUILDS ACROSS THE REGION. SOME MODELS ARE HINTING AT LIGHT BR FORMATION TOWARDS DAYBREAK WEDNESDAY DUE TO CLEAR SKIES AND LIGHT WINDS...BUT EXPECT JUST ENOUGH MIXING BASED ON CURRENT WIND FORECAST TO PREVENT ANY SIGNIFICANT VISIBILITY RESTRICTIONS. OTHERWISE...BREEZY NORTHERLY WINDS ARE EXPECTED TO CONTINUE THROUGH ABOUT 25/00Z AS THE DEPARTING SYSTEM EXITS THE REGION...WITH BREEZY SOUTHERLY WINDS EXPECTED TO DEVELOP AROUND DAYBREAK WEDNESDAY AS THE PRESSURE GRADIENT BEGINS TO TIGHTEN AHEAD OF THE NEXT DISTURBANCE EXPECTED LATE IN THE WEEK. && .HYDROLOGY... ISSUED AT 438 AM CDT TUE SEP 24 2013 OVERALL LITTLE CHANGE IN EXPECTATIONS OVERNIGHT REGARDING PLATTE RIVER FLOODING/FLOODING POTENTIAL. WE CONTINUE TO ADVERTISE TWO OFFICIAL FLOOD WARNINGS AT THIS TIME...ONE FOR THE RIVER GAGE NEAR COZAD...WHICH COVERS THE PLATTE RIVER REACH ACROSS DAWSON COUNTY INTO FAR WESTERN BUFFALO...AND A SECOND FOR THE GAGE NEAR KEARNEY...WHICH COVERS THE REACH OF THE RIVER ALONG THE BUFFALO/PHELPS/KEARNEY COUNTY LINE...AND THEN ACROSS THE MAJORITY OF HALL COUNTY. ALTHOUGH THE LATEST MISSOURI BASIN RIVER FORECAST CENTER (MBRFC) FORECAST TAKES THE GRAND ISLAND GAGE A FEW MILES EAST OF TOWN BARELY INTO MINOR FLOOD STAGE WEDNESDAY NIGHT...WE CONTINUE TO HOLD OFF ON A FORMAL FLOOD WARNING FOR THIS EASTERN HALL COUNTY AREA AND POINTS EAST...MAINLY TO GIVE A BIT MORE TIME TO FINE TUNE THE FORECAST BASED ON UPSTREAM BEHAVIOR AT THE COZAD AND KEARNEY GAGES...AND ALSO THE OVERTON GAUGE WHICH IS NOT AN OFFICIAL FORECAST POINT. OVER THE PAST SEVERAL HOURS...THE GAGE ALONG THE NORTH CHANNEL AT COZAD FINALLY REACHED MINOR FLOOD STAGE OF 6.5 FT AT 9 PM MONDAY EVENING...AND HAS CONTINUED A STEADY CLIMB TO JUST OVER 7.2 FT AS OF 330 AM. AS A RESULT...THE CREST WHICH IS EXPECTED TO OCCUR SOMETIME TODAY HAS BEEN NUDGED UPWARD TO 7.3 FT. THIS IS ANTICIPATED TO BE A PROLONGED CREST WITH ONLY A VERY SLOW FALL TO BELOW FLOOD STAGE BY SOMETIME FRIDAY. MEANWHILE...THE LATEST OVERNIGHT TRENDS ON THE OVERTON AND KEARNEY GAGES CONTINUE TO REFLECT VERY SLOW RISES...AND IT IS YET TO BE SEEN WHETHER THE KEARNEY GAGE IN FACT CAN BREACH THE MINOR FLOOD STAGE OF 6.0 FT BY LATE THIS MORNING AS THE LATEST FORECAST SUGGESTS. AT ANY RATE...A CREST OF 7.2 FT CONTINUES TO BE FORECAST FOR KEARNEY ON WEDNESDAY...AND AGAIN THIS WILL BE A PROLONGED CREST WITH A VERY SLOW FALL...POSSIBLY REMAINING IN FLOOD STAGE THROUGH THE END OF THE MONTH. PLEASE NOTE ONLY MINOR FLOOD STAGE...AND NOT MODERATE/MAJOR CATEGORIES...ARE ANTICIPATED ALONG THE AFOREMENTIONED FORECAST POINTS WITHIN THE NWS HASTINGS CWA...AND THUS THE VAST MAJORITY OF IMPACTS SHOULD REMAIN CONFINED TO THE IMMEDIATE LOWLAND AREAS NEAR THE RIVER CHANNEL/S. THESE RIVER FORECASTS ARE UPDATED REGULARLY PER COORDINATION BETWEEN MBRFC AND NWS HASTINGS...AND MINOR TWEAKS IN CREST HEIGHT AND TIMING REMAIN LIKELY OVER THE COMING DAYS. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...SAR SHORT TERM...PFANNKUCH LONG TERM...HALBLAUB AVIATION...SAR HYDROLOGY...PFANNKUCH
AREA FORECAST DISCUSSION
NWS HASTINGS NE
911 AM CDT TUE SEP 24 2013 .UPDATE... ISSUED AT 904 AM CDT TUE SEP 24 2013 LOW LEVEL STRATUS WILL BE SLOW TO CLEAR ACROSS THE AREA THIS MORNING...WITH A FEW BREAKS ALREADY EVIDENT ACROSS THE WESTERN FRINGES OF THE CWA. EXPECT THIS STRATUS TO CLEAR FROM WEST TO EAST THROUGH THE AFTERNOON...WITH SOME PATCHY DRIZZLE POSSIBLE ACROSS NORTHEASTERN AREAS THROUGH ABOUT NOON. OTHER THAN INCREASING CLOUD COVER AND ADDING SOME PATCHY DRIZZLE PER REPORTS FROM AROUND THE REGION...NO OTHER CHANGES NECESSARY TO THE INHERITED FORECAST AS TEMPERATURES LOOK ON TRACK AND A MOSTLY SUNNY AFTERNOON WILL EVENTUALLY EMERGE ACROSS MOST...IF NOT ALL...OF THE LOCAL FORECAST AREA. UPDATE ISSUED AT 700 AM CDT TUE SEP 24 2013 AS DISCUSSED IN GREATER DETAIL IN THE PRIMARY OVERNIGHT DISCUSSION...LOW STRATUS TRENDS CONTINUE TO BE A HEADACHE. ALTHOUGH A FEW CORRIDORS OF CLEARING REMAIN...MUCH OF THE CWA IS NOW UNDER FAIRLY WIDESPREAD LOW CLOUDS...WITH THE HRRR SUGGESTING THAT GENERALLY THE EASTERN 3/4 OF THE CWA COULD REMAIN FAIRLY SOCKED IN THROUGH MID-DAY. AS A RESULT...YET AGAIN BUMPED UP SKY COVER PERCENTAGES AND SLOWED THE RATE OF WEST-TO-EAST CLEARING...BUT STILL THINKING THAT MOST AREAS SHOULD AVERAGE NO WORSE THAN PARTLY CLOUDY THROUGH THE BALANCE OF THE AFTERNOON. WILL STAY THE COURSE WITH PREVIOUS HIGH TEMPS FOR NOW...AS ANY CLEARING SHOULD RESULT IN A QUICK RISE AND HELP OFFSET ANY POTENTIAL DELAY IN WARMING FROM MORNING CLOUD COVER. ON ONE FINAL NOTE...RADAR TRENDS SUPPORTED KILLING THE SLIGHT POPS THAT ORIGINALLY LINGERED IN A FEW FAR NORTHEAST COUNTIES THROUGH 15Z/10AM...SO NOW THE FORECAST IS OFFICIALLY VOID OF ALL PRECIP MENTION UNTIL THURS NIGHT. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 438 AM CDT TUE SEP 24 2013 ALTHOUGH MOST IF NOT ALL OF THE CWA IS LOOKING AT A DRY AND FAIRLY UNEVENTFUL UPCOMING 24 HOURS...ESPECIALLY THE DAYTIME HOURS HAVE BECOME TRICKIER-THAN-EXPECTED MAINLY REGARDING THE EVOLUTION OF SKY COVER/TEMPERATURES...AS LOW CLOUDS COULD BE STUBBORNLY SLOW TO DEPART MAINLY WITHIN THE EASTERN 1/2 OF THE CWA...BRINGING 5+ DEGREE TEMP BUST POTENTIAL VERY MUCH INTO PLAY. 08Z OBJECTIVE SURFACE ANALYSIS HIGHLIGHTS A SLOWLY-WEAKENING 1004 MILLIBAR LOW PRESSURE CENTER...CENTERED OVER THE CLAY/FILLMORE COUNTY AREA...WHILE IN ITS WAKE THE LEADING EDGES OF HIGH PRESSURE AROUND 1016MB HAS WORKED INTO THE NEB PANHANDLE. WITH THE MAJORITY OF THE CWA POSITIONED BEHIND THE DEPARTING LOW...EARLY MORNING BREEZES ARE MAINLY FROM THE WEST-NORTHWEST...WITH THE STRONGEST SPEEDS WITH GUSTS OF 20+ MPH FOCUSED ACROSS THE SOUTHWESTERN HALF OF THE AREA...WITH LIGHTER SPEEDS STILL HOLDING ON FOR AT LEAST A FEW MORE HOURS WITHIN MUCH OF THE NORTHEAST 1/2. ALOFT...WATER VAPOR IMAGERY AND SHORT TERM MODEL DATA CLEARLY REVEAL A WELL- DEFINED...NOT QUITE VERTICALLY STACKED LOW PRESSURE SYSTEM DEPARTING EASTWARD ACROSS THE EASTERN 1/4 OF NEB...WITH A CLOSED 500MB CIRCULATION CENTERED NEAR NORFOLK. AS A RESULT...THE PRIMARY MID LEVEL CONVERGENCE/DEFORMATION ZONE AT THIS HOUR IS FOCUSING WIDESPREAD MAINLY LIGHT RAIN 50+ MILES NORTHEAST OF THE CWA. CLOUD-WISE...11-3.9 MICRON SATELLITE IMAGERY DEPICTS A FAIRLY COMPLEX AND EVER-CHANGING MIXTURE OF CLEAR SKIES ALONG WITH PASSING BATCHES OF MID CLOUDS AND LOW STRATUS. WHILE MOST OF THESE LOWER CEILINGS WITHIN THE CWA ARE AT/ABOVE 1500 FT...A CORRIDOR OF LOWER CEILINGS BETWEEN 500-1000 FT SEEMS TO BE LURKING JUST NORTHWEST OF THE CWA ALONG A BROKEN BOW-AINSWORTH AXIS...WITH THESE LOW CLOUDS POSSIBLY EVEN SUPPORTING SOME PATCHY LIGHT DRIZZLE. TEMP-WISE...MOST OF THE CWA APPEARS HEADED FOR OVERNIGHT LOWS IN THE MID 50S...WITH ANY LOW 50S/UPPER 40S MOST FAVORED IN FAR WESTERN COUNTIES. AS THE EARLY MORNING/DAYTIME HOURS WEAR ON...THE BIG PICTURE ALOFT INVOLVES THE MID LEVEL SHORTWAVE TROUGH/ASSOCIATED CLOSED LOW CONTINUING ITS STEADY TREK EASTWARD...WITH THE 500MB CIRCULATION CENTER INTO SOUTHWEST IA BY 18Z...AND THEN OVER NORTH CENTRAL MO BY 00Z/7PM. AS THIS LOW DEPARTS...A BROAD AREA OF SHORTWAVE RIDGING AND ASSOCIATED HEIGHT RISES WILL OVERSPREAD THE CENTRAL PLAINS. AT THE SURFACE...THE LOW PRESSURE CENTER CURRENTLY OVER SOUTHEAST NEB WILL CONTINUE TO WEAKEN AS IT SLIDES INTO CENTRAL MO OVER THE COURSE OF THE DAY...ALLOWING A MODEST RIDGE AXIS TO BUILD INTO THE LOCAL AREA WITH TIME AND RELAX THE SURFACE PRESSURE GRADIENT. HOWEVER...BREEZES WILL STILL BE FAIRLY ELEVATED FOR MUCH OF THE DAY TODAY...LARGELY OWING TO MIXING CLIMBING UP TO AROUND 850MB...WHERE AN ENHANCED CORRIDOR OF 30-40KT NORTHERLY WINDS WILL LINGER THROUGH MID-DAY BEFORE STEADILY WEAKENING IN THE AFTERNOON. THE NET RESULT WILL BE SUSTAINED NORTH-NORTHWEST WIND SPEEDS 15-20 MPH WITH GUSTS 25+ MPH THROUGH THIS MORNING...BEFORE DIMINISHING TO MORE SO SUSTAINED 10-15 MPH SPEEDS THIS AFTERNOON...AND ONLY 5-10 MPH CLOSER TO SUNSET. AS FOR PRECIP CHANCES...ALTHOUGH RADAR TRENDS AND SHORT TERM MODEL DATA INCLUDING THE HRRR PRETTY STRONGLY SUGGEST THAN ANY RISK OF MEASURABLE LIGHT RAIN SHOULD BE OVER BY 12Z...WENT AHEAD AND LINGERED A TOKEN 20 POP IN THE EXTREME NORTHEAST NANCE/MERRICK/POLK AREA THROUGH 15Z IN CASE SOMETHING MANAGES TO STILL WRAP AROUND THE BACK SIDE OF THE LOW. THE BIG CHALLENGE TODAY SEEMS TO BE CENTERED AROUND SKY COVER. 24 HOURS AGO...IT WAS ASSUMED THAT MID LEVEL CLOUDS WOULD QUICKLY MOVE OFF EAST OF THE CWA TODAY WITH THE PARENT SYSTEM. HOWEVER...LATEST SATELLITE AND SHORT TERM MODEL DATA INCLUDING THE HRRR LOW CLOUD PRODUCT NOW SUGGEST THAT THE AREAL COVERAGE OF LOW STRATUS MAY IN FACT INCREASE BEFORE SUNRISE FROM THE NORTHWEST...AND THEN POSSIBLY HANG VERY STUBBORNLY MAINLY ACROSS THE CENTRAL/EASTERN CWA EVEN INTO THE AFTERNOON HOURS. ALTHOUGH HAVE NOT BOUGHT FULL-BORE INTO THE VERY PESSIMISTIC RUC/HRRR SOLUTIONS REGARDING LOW CLOUDS TODAY...DID INCREASE SKY COVER PERCENTAGES VERSUS PREVIOUS...AND ALSO DELAYED THE WEST-EAST CLEARING TREND. HOWEVER...PLEASE NOTE THAT ESPECIALLY EASTERN COUNTIES ALONG/NEAR HIGHWAY 81 MAY REALLY STRUGGLE TO SEE MUCH SUN UNTIL MAYBE LATE AFTERNOON...AND DAY SHIFT MAY HAVE TO MAKE SOME PRETTY NOTICEABLE ADJUSTMENTS TO SKY COVER AND RESULTANT HIGH TEMPS. FOR NOW THOUGH...OPTED TO ONLY SHAVE 1-2 DEGREES OFF PREVIOUS HIGHS IN MOST AREAS...RANGING FROM LOW 70S FAR EAST TO UPPER 70S FAR SOUTHWEST...AND AROUND 73 TRI- CITIES. IF CLOUDS ARE SLOW TO DEPART HOWEVER...SOME EASTERN AREAS MAY STRUGGLE TO LEAVE THE 60S. ON ONE FINAL DAYTIME NOTE...ALTHOUGH HAVE DEWPOINTS DROPPING INTO THE LOW-MID 40S ACROSS MUCH OF THE WESTERN CWA DURING THE AFTERNOON...THESE VALUES ARE NOT QUITE AS LOW AS ANTICIPATED 24 HOURS AGO...AND THIS KEEPS ANY AFTERNOON RELATIVE HUMIDITY VALUES AS LOW AS 25-30 PERCENT CONFINED TO MAINLY JUST THE FURNAS COUNTY AREA. FOR THE EVENING/NIGHT 00Z-12Z PERIOD...WILL RUN WITH THE ASSUMPTION THAT EVEN IF LOW STRATUS LINGERS QUITE AWHILE INTO THE AFTERNOON IN SOME AREAS...THAT IT SHOULD BE SAFELY EAST OF THE CWA BY SUNSET...THUS RESULTING IN A CLEAR OVERNIGHT AREA-WIDE WITH ESSENTIALLY ZERO RISK OF PRECIP. ON THE BIG PICTURE...THE HEART OF THE AFOREMENTIONED MID/UPPER LEVEL SHORTWAVE RIDGE AXIS WILL PASS DIRECTLY OVER THE CWA...VERY SIMILAR TO LAST FRIDAY NIGHT. ALSO SIMILAR TO LAST FRIDAY AT THE SURFACE...VERY LIGHT/VARIABLE BREEZES IN THE EVENING WILL GRADUALLY GIVE WAY TO LIGHT SOUTHEAST BREEZES LATER IN THE NIGHT AS THE SURFACE RIDGE AXIS DRIFTS EASTWARD ACROSS THE CWA. HOWEVER...COMPARED TO 24 HOURS AGO IT NOW APPEARS THAT DEWPOINTS WILL NOT DROP OFF QUITE AS FAR...AND THUS GUIDANCE/MODELS HAVE TRENDED A FEW DEGREES MILDER FOR OVERNIGHT LOWS. AS A RESULT...NUDGED UP LOWS 1-2 DEGREES MOST AREAS VERSUS PREVIOUS...AIMING MOST OF THE CWA BETWEEN 50-53...BUT WITH PREDOMINANTLY MID-UPPER 40S IN A FEW OF THE FAR WESTERN NORTHERN/COUNTIES. DESPITE THE LIGHT OVERNIGHT BREEZES...AM NOT EXPECTING IMPACTFUL FOG TO BE AN ISSUE...ALTHOUGH SOME VERY LIGHT FOG/HAZE IS PROBABLY NOT OUT OF THE QUESTION...BUT IS ALSO NOT WORTH ADVERTISING IN THE FORECAST. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 438 AM CDT TUE SEP 24 2013 PATTERN: THE CPC OBSERVED H5 HGT ANOMALY TOOLS SHOW THAT THE LOW FREQUENCY /LGWV/ FLOW OF THE PAST 90 DAYS LARGELY REMAINS IN PLACE OVER THE NRN HEMISPHERE. HOWEVER...WE HAVE RECENTLY SEEN AMPLIFICATION ESPECIALLY WITH THE ERN PAC TROF. OTHER ADJUSTMENTS SHOW THAT THE +HGT ANOMALY WHICH HAS RESIDED OVER WRN N AMERICA HAS SHIFT TO THE E...ALLOWING THE TEMPORARY ESTABLISHMENT OF A WRN N AMERICA TROF. THIS TROF WILL ONLY BE WITH US THIS WEEK AND OFFERS ONE MORE SHOT AT DECENT RAINFALL. THE NAO HAS TURNED SHARPLY NEGATIVE AS THE PERSISTENT -HGT ANOMALY OVER GREENLAND HAS BEEN REPLACED WITH +HGT ANOMALIES. THIS COMBINED WITH THE A PAIR OF STORMS CROSSING THE NRN PAC WILL RETURN RIDGING TO WRN N AMERICA THIS WEEKEND. SO THE BOTTOM LINE IS...EXCEPT FOR A BRIEF WINDOW THU NGT-FRI...DRY WX WILL CONT. TEMPS WILL BE VARIABLE BUT PROBABLY AVERAGE PRETTY CLOSE TO NORMAL OVER THE NEXT 10 DAYS. ALOFT: SW FLOW WILL DEVELOP OVER THE CNTRL PLAINS WED AND CONT THRU FRI...AS THE WRN USA TROF FULLY RELOADS. CYCLOGENESIS WILL OCCUR THU...WITH THE MAIN UPR LOW HEADING N INTO CANADA. THE MAIN UPR TROF WILL BE LEFT BEHIND AND BEGIN LIFTING NE...CROSSING THE CNTRL PLAINS SAT. NW FLOW FOLLOWS SUN-MON BUT THERE IS DISAGREEMENT/UNCERTAINTY IN THE AMPLITUDE OF THE RIDGE MOVING INTO THE W. SFC: A PAC COLD FRONT WILL EXTEND FROM THE NRN ROCKIES TO CNTRL CA WED...WITH A LEE-SIDE TROF IN PLACE. THIS FRONT WILL ADVANCE E AND EMERGE ONTO THE PLAINS BY DAWN THU. HOWEVER...THE SRN PORTION WILL REMAIN STATIONARY DUE TO MINIMAL MOVEMENT OF THE BASE OF THE TROF. THE SLOW EJECTION OF THE TROF MEANS THE FWD PROGRESS OF THE FRONT WILL BE SLOW. WRN USA HIGH PRES BUILDS IN SAT THRU MON. WITH SW FLOW ALOFT ON BOTH SIDES OF THIS FRONT...IT WILL HAVE AN ANABATIC CHARACTER. THE SLOW MOVEMENT OFFERS THE OPPORTUNITY FOR ENTRAINMENT OF GULF MSTR. WE ARE SEEING A NARROW RIBBON OF MSTR FCST TO SURGE NWD FRI...WITH PW NEARING 1.6". HAZARDS: NOTHING SUBSTANTIAL...BUT THERE IS A LATE-WEEK THUNDER THREAT. RISK OF SVR LOOKS VERY LOW. THE DAILY DETAILS... WED: WARM SECTOR. BREEZY AND WARMER BY 7-10F. WED NGT: A STRONG LLJ WILL DEVELOP /55-60 KTS/ WITH LOW-LVL WINDS VEERING TO THE SW. THIS WILL ADVECT AN EML ONTO THE PLAINS... IMPOSING A SUBSTANTIAL CAP. THU: WARM SECTOR. VERY WARM. ADD ANOTHER 3-7F TO WED AND THIS WILL PUT HIGHS 10F ABOVE NORMAL. HIGHS IN THE LWR 90S LOOK LIKE A GOOD BET OVER N-CNTRL KS. THU NGT: SOME ISOLATED HIGH-BASED SHWRS/TSTMS ARE POSSIBLE. THIS REALLY DEPENDS ON WHERE THE LLJ CORE SETS UP. THE EC IS FURTHER N THAN THE GFS AND NAM. IF SHWRS/TSTMS DEVELOP RAINFALL AMTS WILL BE VERY LIGHT. FRI: WARM SECTOR...BUT THE FRONT THREATENS THE NW FRINGE OF THE FCST AREA DURING PEAK HEATING. MOST OF THE FCST AREA SHOULD REMAIN DRY FOR MOST OF THE DAY. PCPN AND CLOUDS WILL BE MOST EXTENSIVE BEHIND THE FRONT WHICH SHOULD RESULT IN A SUBSTANTIAL TEMP CONTRAST ACROSS THE STATE. AHEAD OF THE FRONT EXPECT THE ATMS TO BE CAPPED. SCT TSTMS SHOULD ONLY ERUPT IN THE IMMEDIATE VICINITY OF THE FRONT IN THE LATE AFTN. SEVERE?: PROBABLY NOT BUT IF THERE IS A THREAT IS LOOKS VERY MARGINAL DUE TO WEAK INSTABILITY. HOWEVER...STRENGTH OF THE WIND FIELDS AND THE DRY SUB-CLOUD LAYER COULD SUPPORT SOME DECENT WINDS IF A STRONGER STORM OR TWO CAN DEVELOP. FRI NGT: COLD FRONTAL PASSAGE. THE SETUP LOOKS GOOD FOR SOME DECENT POST-FRONTAL RAINFALL IN SOME LOCATIONS. SAT: MUCH COOLER! PROBABLY 20F COOLER THAN FRI. IN FACT...WITH THE UPR TROF MOVING THRU...BELIEVE FUTURE FCSTS WILL END UP LOWERING HIGHS ANOTHER 5F OR SO. CONSENSUS OF 2M TEMPS CURRENTLY OFFERS 57F AT ORD AND 67F AT BELOIT. NOT MUCH DIFF FROM THE 12Z/18Z CYCLES. SWEATSHIRTS AND JACKETS MAY BE NEEDED FOR OUTDOOR ACTIVITIES. CLOUDY TO START WITH A COUPLE LEFTOVER SHWRS OR SOME PATCHY DRZL. CLEARING PROGRESSES FROM W TO E IN THE AFTN. SUN-MON: BACK TO NICER WX. TEMPS REBOUND AND WITH LOW PRES MOVING THRU THE CANADIAN ROCKIES...A LEE-SIDE TROF WILL DEVELOP AND MAY ACTUALLY PROGRESS THRU THE FCST AREA WITH AN ATTENDANT THERMAL RIDGE. HIGHS SHOULD BE BACK INTO THE LOW-MID 70S SUN AND UPR 70S-80 MON? && .AVIATION...(FOR THE 12Z KGRI TAF THROUGH 12Z WEDNESDAY MORNING) ISSUED AT 700 AM CDT TUE SEP 24 2013 ALTHOUGH CONFIDENCE REMAINS HIGH IN VFR VISIBILITY THROUGH THE NEXT 24 HOURS...CEILING TRENDS WILL CONTINUE TO BE A CHALLENGE ESPECIALLY THROUGH THE FIRST 6 HOURS TODAY...AS THE LOCAL AREA IS CURRENTLY A MIXED BAG OF CLEAR SKIES INTERSPERSED WITH PASSING BATCHES OF LOW VFR...MVFR AND EVEN IFR LOW CLOUDS. BASED ON LATEST OBS AND SATELLITE TRENDS...WENT AHEAD AND INTRODUCED PREVAILING HIGHER MVFR CEILING THROUGH THE NEXT 6 HOURS...WITH A TEMPO GROUP FOR LOWER MVFR CEILING FOR THE FIRST 4 HOURS. SOMETIME EARLY-MID AFTERNOON...ANTICIPATE ANY LOW CEILINGS TO SCATTER OUT OR MOVE OFF TO THE EAST....WITH FAIRLY HIGH CONFIDENCE IN NO WORSE THAN CLEAR/MOSTLY CLEAR SKIES DURING AT LEAST THE FINAL 15 HOURS OF THE PERIOD. AS FOR SURFACE WINDS...STEADY NORTHWEST BREEZES WILL PERSIST THROUGH THE NEXT SEVERAL HOURS...WITH GUST POTENTIAL TO AT LEAST 22KT OR HIGHER LASTING THROUGH MID-DAY BEFORE STEADILY DIMINISHING DURING THE AFTERNOON...AND BECOMING LIGHT/VARIABLE TONIGHT. && .HYDROLOGY... ISSUED AT 438 AM CDT TUE SEP 24 2013 OVERALL LITTLE CHANGE IN EXPECTATIONS OVERNIGHT REGARDING PLATTE RIVER FLOODING/FLOODING POTENTIAL. WE CONTINUE TO ADVERTISE TWO OFFICIAL FLOOD WARNINGS AT THIS TIME...ONE FOR THE RIVER GAGE NEAR COZAD...WHICH COVERS THE PLATTE RIVER REACH ACROSS DAWSON COUNTY INTO FAR WESTERN BUFFALO...AND A SECOND FOR THE GAGE NEAR KEARNEY...WHICH COVERS THE REACH OF THE RIVER ALONG THE BUFFALO/PHELPS/KEARNEY COUNTY LINE...AND THEN ACROSS THE MAJORITY OF HALL COUNTY. ALTHOUGH THE LATEST MISSOURI BASIN RIVER FORECAST CENTER (MBRFC) FORECAST TAKES THE GRAND ISLAND GAGE A FEW MILES EAST OF TOWN BARELY INTO MINOR FLOOD STAGE WEDNESDAY NIGHT...WE CONTINUE TO HOLD OFF ON A FORMAL FLOOD WARNING FOR THIS EASTERN HALL COUNTY AREA AND POINTS EAST...MAINLY TO GIVE A BIT MORE TIME TO FINE TUNE THE FORECAST BASED ON UPSTREAM BEHAVIOR AT THE COZAD AND KEARNEY GAGES...AND ALSO THE OVERTON GAUGE WHICH IS NOT AN OFFICIAL FORECAST POINT. OVER THE PAST SEVERAL HOURS...THE GAGE ALONG THE NORTH CHANNEL AT COZAD FINALLY REACHED MINOR FLOOD STAGE OF 6.5 FT AT 9 PM MONDAY EVENING...AND HAS CONTINUED A STEADY CLIMB TO JUST OVER 7.2 FT AS OF 330 AM. AS A RESULT...THE CREST WHICH IS EXPECTED TO OCCUR SOMETIME TODAY HAS BEEN NUDGED UPWARD TO 7.3 FT. THIS IS ANTICIPATED TO BE A PROLONGED CREST WITH ONLY A VERY SLOW FALL TO BELOW FLOOD STAGE BY SOMETIME FRIDAY. MEANWHILE...THE LATEST OVERNIGHT TRENDS ON THE OVERTON AND KEARNEY GAGES CONTINUE TO REFLECT VERY SLOW RISES...AND IT IS YET TO BE SEEN WHETHER THE KEARNEY GAGE IN FACT CAN BREACH THE MINOR FLOOD STAGE OF 6.0 FT BY LATE THIS MORNING AS THE LATEST FORECAST SUGGESTS. AT ANY RATE...A CREST OF 7.2 FT CONTINUES TO BE FORECAST FOR KEARNEY ON WEDNESDAY...AND AGAIN THIS WILL BE A PROLONGED CREST WITH A VERY SLOW FALL...POSSIBLY REMAINING IN FLOOD STAGE THROUGH THE END OF THE MONTH. PLEASE NOTE ONLY MINOR FLOOD STAGE...AND NOT MODERATE/MAJOR CATEGORIES...ARE ANTICIPATED ALONG THE AFOREMENTIONED FORECAST POINTS WITHIN THE NWS HASTINGS CWA...AND THUS THE VAST MAJORITY OF IMPACTS SHOULD REMAIN CONFINED TO THE IMMEDIATE LOWLAND AREAS NEAR THE RIVER CHANNEL/S. THESE RIVER FORECASTS ARE UPDATED REGULARLY PER COORDINATION BETWEEN MBRFC AND NWS HASTINGS...AND MINOR TWEAKS IN CREST HEIGHT AND TIMING REMAIN LIKELY OVER THE COMING DAYS. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...SAR SHORT TERM...PFANNKUCH LONG TERM...HALBLAUB AVIATION...PFANNKUCH HYDROLOGY...PFANNKUCH
AREA FORECAST DISCUSSION
NWS HASTINGS NE
705 AM CDT TUE SEP 24 2013 .UPDATE... ISSUED AT 700 AM CDT TUE SEP 24 2013 AS DISCUSSED IN GREATER DETAIL IN THE PRIMARY OVERNIGHT DISCUSSION...LOW STRATUS TRENDS CONTINUE TO BE A HEADACHE. ALTHOUGH A FEW CORRIDORS OF CLEARING REMAIN...MUCH OF THE CWA IS NOW UNDER FAIRLY WIDESPREAD LOW CLOUDS...WITH THE HRRR SUGGESTING THAT GENERALLY THE EASTERN 3/4 OF THE CWA COULD REMAIN FAIRLY SOCKED IN THROUGH MID-DAY. AS A RESULT...YET AGAIN BUMPED UP SKY COVER PERCENTAGES AND SLOWED THE RATE OF WEST-TO-EAST CLEARING...BUT STILL THINKING THAT MOST AREAS SHOULD AVERAGE NO WORSE THAN PARTLY CLOUDY THROUGH THE BALANCE OF THE AFTERNOON. WILL STAY THE COURSE WITH PREVIOUS HIGH TEMPS FOR NOW...AS ANY CLEARING SHOULD RESULT IN A QUICK RISE AND HELP OFFSET ANY POTENTIAL DELAY IN WARMING FROM MORNING CLOUD COVER. ON ONE FINAL NOTE...RADAR TRENDS SUPPORTED KILLING THE SLIGHT POPS THAT ORIGINALLY LINGERED IN A FEW FAR NORTHEAST COUNTIES THROUGH 15Z/10AM...SO NOW THE FORECAST IS OFFICIALLY VOID OF ALL PRECIP MENTION UNTIL THURS NIGHT. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 438 AM CDT TUE SEP 24 2013 ALTHOUGH MOST IF NOT ALL OF THE CWA IS LOOKING AT A DRY AND FAIRLY UNEVENTFUL UPCOMING 24 HOURS...ESPECIALLY THE DAYTIME HOURS HAVE BECOME TRICKIER-THAN-EXPECTED MAINLY REGARDING THE EVOLUTION OF SKY COVER/TEMPERATURES...AS LOW CLOUDS COULD BE STUBBORNLY SLOW TO DEPART MAINLY WITHIN THE EASTERN 1/2 OF THE CWA...BRINGING 5+ DEGREE TEMP BUST POTENTIAL VERY MUCH INTO PLAY. 08Z OBJECTIVE SURFACE ANALYSIS HIGHLIGHTS A SLOWLY-WEAKENING 1004 MILLIBAR LOW PRESSURE CENTER...CENTERED OVER THE CLAY/FILLMORE COUNTY AREA...WHILE IN ITS WAKE THE LEADING EDGES OF HIGH PRESSURE AROUND 1016MB HAS WORKED INTO THE NEB PANHANDLE. WITH THE MAJORITY OF THE CWA POSITIONED BEHIND THE DEPARTING LOW...EARLY MORNING BREEZES ARE MAINLY FROM THE WEST-NORTHWEST...WITH THE STRONGEST SPEEDS WITH GUSTS OF 20+ MPH FOCUSED ACROSS THE SOUTHWESTERN HALF OF THE AREA...WITH LIGHTER SPEEDS STILL HOLDING ON FOR AT LEAST A FEW MORE HOURS WITHIN MUCH OF THE NORTHEAST 1/2. ALOFT...WATER VAPOR IMAGERY AND SHORT TERM MODEL DATA CLEARLY REVEAL A WELL- DEFINED...NOT QUITE VERTICALLY STACKED LOW PRESSURE SYSTEM DEPARTING EASTWARD ACROSS THE EASTERN 1/4 OF NEB...WITH A CLOSED 500MB CIRCULATION CENTERED NEAR NORFOLK. AS A RESULT...THE PRIMARY MID LEVEL CONVERGENCE/DEFORMATION ZONE AT THIS HOUR IS FOCUSING WIDESPREAD MAINLY LIGHT RAIN 50+ MILES NORTHEAST OF THE CWA. CLOUD-WISE...11-3.9 MICRON SATELLITE IMAGERY DEPICTS A FAIRLY COMPLEX AND EVER-CHANGING MIXTURE OF CLEAR SKIES ALONG WITH PASSING BATCHES OF MID CLOUDS AND LOW STRATUS. WHILE MOST OF THESE LOWER CEILINGS WITHIN THE CWA ARE AT/ABOVE 1500 FT...A CORRIDOR OF LOWER CEILINGS BETWEEN 500-1000 FT SEEMS TO BE LURKING JUST NORTHWEST OF THE CWA ALONG A BROKEN BOW-AINSWORTH AXIS...WITH THESE LOW CLOUDS POSSIBLY EVEN SUPPORTING SOME PATCHY LIGHT DRIZZLE. TEMP-WISE...MOST OF THE CWA APPEARS HEADED FOR OVERNIGHT LOWS IN THE MID 50S...WITH ANY LOW 50S/UPPER 40S MOST FAVORED IN FAR WESTERN COUNTIES. AS THE EARLY MORNING/DAYTIME HOURS WEAR ON...THE BIG PICTURE ALOFT INVOLVES THE MID LEVEL SHORTWAVE TROUGH/ASSOCIATED CLOSED LOW CONTINUING ITS STEADY TREK EASTWARD...WITH THE 500MB CIRCULATION CENTER INTO SOUTHWEST IA BY 18Z...AND THEN OVER NORTH CENTRAL MO BY 00Z/7PM. AS THIS LOW DEPARTS...A BROAD AREA OF SHORTWAVE RIDGING AND ASSOCIATED HEIGHT RISES WILL OVERSPREAD THE CENTRAL PLAINS. AT THE SURFACE...THE LOW PRESSURE CENTER CURRENTLY OVER SOUTHEAST NEB WILL CONTINUE TO WEAKEN AS IT SLIDES INTO CENTRAL MO OVER THE COURSE OF THE DAY...ALLOWING A MODEST RIDGE AXIS TO BUILD INTO THE LOCAL AREA WITH TIME AND RELAX THE SURFACE PRESSURE GRADIENT. HOWEVER...BREEZES WILL STILL BE FAIRLY ELEVATED FOR MUCH OF THE DAY TODAY...LARGELY OWING TO MIXING CLIMBING UP TO AROUND 850MB...WHERE AN ENHANCED CORRIDOR OF 30-40KT NORTHERLY WINDS WILL LINGER THROUGH MID-DAY BEFORE STEADILY WEAKENING IN THE AFTERNOON. THE NET RESULT WILL BE SUSTAINED NORTH-NORTHWEST WIND SPEEDS 15-20 MPH WITH GUSTS 25+ MPH THROUGH THIS MORNING...BEFORE DIMINISHING TO MORE SO SUSTAINED 10-15 MPH SPEEDS THIS AFTERNOON...AND ONLY 5-10 MPH CLOSER TO SUNSET. AS FOR PRECIP CHANCES...ALTHOUGH RADAR TRENDS AND SHORT TERM MODEL DATA INCLUDING THE HRRR PRETTY STRONGLY SUGGEST THAN ANY RISK OF MEASURABLE LIGHT RAIN SHOULD BE OVER BY 12Z...WENT AHEAD AND LINGERED A TOKEN 20 POP IN THE EXTREME NORTHEAST NANCE/MERRICK/POLK AREA THROUGH 15Z IN CASE SOMETHING MANAGES TO STILL WRAP AROUND THE BACK SIDE OF THE LOW. THE BIG CHALLENGE TODAY SEEMS TO BE CENTERED AROUND SKY COVER. 24 HOURS AGO...IT WAS ASSUMED THAT MID LEVEL CLOUDS WOULD QUICKLY MOVE OFF EAST OF THE CWA TODAY WITH THE PARENT SYSTEM. HOWEVER...LATEST SATELLITE AND SHORT TERM MODEL DATA INCLUDING THE HRRR LOW CLOUD PRODUCT NOW SUGGEST THAT THE AREAL COVERAGE OF LOW STRATUS MAY IN FACT INCREASE BEFORE SUNRISE FROM THE NORTHWEST...AND THEN POSSIBLY HANG VERY STUBBORNLY MAINLY ACROSS THE CENTRAL/EASTERN CWA EVEN INTO THE AFTERNOON HOURS. ALTHOUGH HAVE NOT BOUGHT FULL-BORE INTO THE VERY PESSIMISTIC RUC/HRRR SOLUTIONS REGARDING LOW CLOUDS TODAY...DID INCREASE SKY COVER PERCENTAGES VERSUS PREVIOUS...AND ALSO DELAYED THE WEST-EAST CLEARING TREND. HOWEVER...PLEASE NOTE THAT ESPECIALLY EASTERN COUNTIES ALONG/NEAR HIGHWAY 81 MAY REALLY STRUGGLE TO SEE MUCH SUN UNTIL MAYBE LATE AFTERNOON...AND DAY SHIFT MAY HAVE TO MAKE SOME PRETTY NOTICEABLE ADJUSTMENTS TO SKY COVER AND RESULTANT HIGH TEMPS. FOR NOW THOUGH...OPTED TO ONLY SHAVE 1-2 DEGREES OFF PREVIOUS HIGHS IN MOST AREAS...RANGING FROM LOW 70S FAR EAST TO UPPER 70S FAR SOUTHWEST...AND AROUND 73 TRI- CITIES. IF CLOUDS ARE SLOW TO DEPART HOWEVER...SOME EASTERN AREAS MAY STRUGGLE TO LEAVE THE 60S. ON ONE FINAL DAYTIME NOTE...ALTHOUGH HAVE DEWPOINTS DROPPING INTO THE LOW-MID 40S ACROSS MUCH OF THE WESTERN CWA DURING THE AFTERNOON...THESE VALUES ARE NOT QUITE AS LOW AS ANTICIPATED 24 HOURS AGO...AND THIS KEEPS ANY AFTERNOON RELATIVE HUMIDITY VALUES AS LOW AS 25-30 PERCENT CONFINED TO MAINLY JUST THE FURNAS COUNTY AREA. FOR THE EVENING/NIGHT 00Z-12Z PERIOD...WILL RUN WITH THE ASSUMPTION THAT EVEN IF LOW STRATUS LINGERS QUITE AWHILE INTO THE AFTERNOON IN SOME AREAS...THAT IT SHOULD BE SAFELY EAST OF THE CWA BY SUNSET...THUS RESULTING IN A CLEAR OVERNIGHT AREA-WIDE WITH ESSENTIALLY ZERO RISK OF PRECIP. ON THE BIG PICTURE...THE HEART OF THE AFOREMENTIONED MID/UPPER LEVEL SHORTWAVE RIDGE AXIS WILL PASS DIRECTLY OVER THE CWA...VERY SIMILAR TO LAST FRIDAY NIGHT. ALSO SIMILAR TO LAST FRIDAY AT THE SURFACE...VERY LIGHT/VARIABLE BREEZES IN THE EVENING WILL GRADUALLY GIVE WAY TO LIGHT SOUTHEAST BREEZES LATER IN THE NIGHT AS THE SURFACE RIDGE AXIS DRIFTS EASTWARD ACROSS THE CWA. HOWEVER...COMPARED TO 24 HOURS AGO IT NOW APPEARS THAT DEWPOINTS WILL NOT DROP OFF QUITE AS FAR...AND THUS GUIDANCE/MODELS HAVE TRENDED A FEW DEGREES MILDER FOR OVERNIGHT LOWS. AS A RESULT...NUDGED UP LOWS 1-2 DEGREES MOST AREAS VERSUS PREVIOUS...AIMING MOST OF THE CWA BETWEEN 50-53...BUT WITH PREDOMINANTLY MID-UPPER 40S IN A FEW OF THE FAR WESTERN NORTHERN/COUNTIES. DESPITE THE LIGHT OVERNIGHT BREEZES...AM NOT EXPECTING IMPACTFUL FOG TO BE AN ISSUE...ALTHOUGH SOME VERY LIGHT FOG/HAZE IS PROBABLY NOT OUT OF THE QUESTION...BUT IS ALSO NOT WORTH ADVERTISING IN THE FORECAST. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 438 AM CDT TUE SEP 24 2013 PATTERN: THE CPC OBSERVED H5 HGT ANOMALY TOOLS SHOW THAT THE LOW FREQUENCY /LGWV/ FLOW OF THE PAST 90 DAYS LARGELY REMAINS IN PLACE OVER THE NRN HEMISPHERE. HOWEVER...WE HAVE RECENTLY SEEN AMPLIFICATION ESPECIALLY WITH THE ERN PAC TROF. OTHER ADJUSTMENTS SHOW THAT THE +HGT ANOMALY WHICH HAS RESIDED OVER WRN N AMERICA HAS SHIFT TO THE E...ALLOWING THE TEMPORARY ESTABLISHMENT OF A WRN N AMERICA TROF. THIS TROF WILL ONLY BE WITH US THIS WEEK AND OFFERS ONE MORE SHOT AT DECENT RAINFALL. THE NAO HAS TURNED SHARPLY NEGATIVE AS THE PERSISTENT -HGT ANOMALY OVER GREENLAND HAS BEEN REPLACED WITH +HGT ANOMALIES. THIS COMBINED WITH THE A PAIR OF STORMS CROSSING THE NRN PAC WILL RETURN RIDGING TO WRN N AMERICA THIS WEEKEND. SO THE BOTTOM LINE IS...EXCEPT FOR A BRIEF WINDOW THU NGT-FRI...DRY WX WILL CONT. TEMPS WILL BE VARIABLE BUT PROBABLY AVERAGE PRETTY CLOSE TO NORMAL OVER THE NEXT 10 DAYS. ALOFT: SW FLOW WILL DEVELOP OVER THE CNTRL PLAINS WED AND CONT THRU FRI...AS THE WRN USA TROF FULLY RELOADS. CYCLOGENESIS WILL OCCUR THU...WITH THE MAIN UPR LOW HEADING N INTO CANADA. THE MAIN UPR TROF WILL BE LEFT BEHIND AND BEGIN LIFTING NE...CROSSING THE CNTRL PLAINS SAT. NW FLOW FOLLOWS SUN-MON BUT THERE IS DISAGREEMENT/UNCERTAINTY IN THE AMPLITUDE OF THE RIDGE MOVING INTO THE W. SFC: A PAC COLD FRONT WILL EXTEND FROM THE NRN ROCKIES TO CNTRL CA WED...WITH A LEE-SIDE TROF IN PLACE. THIS FRONT WILL ADVANCE E AND EMERGE ONTO THE PLAINS BY DAWN THU. HOWEVER...THE SRN PORTION WILL REMAIN STATIONARY DUE TO MINIMAL MOVEMENT OF THE BASE OF THE TROF. THE SLOW EJECTION OF THE TROF MEANS THE FWD PROGRESS OF THE FRONT WILL BE SLOW. WRN USA HIGH PRES BUILDS IN SAT THRU MON. WITH SW FLOW ALOFT ON BOTH SIDES OF THIS FRONT...IT WILL HAVE AN ANABATIC CHARACTER. THE SLOW MOVEMENT OFFERS THE OPPORTUNITY FOR ENTRAINMENT OF GULF MSTR. WE ARE SEEING A NARROW RIBBON OF MSTR FCST TO SURGE NWD FRI...WITH PW NEARING 1.6". HAZARDS: NOTHING SUBSTANTIAL...BUT THERE IS A LATE-WEEK THUNDER THREAT. RISK OF SVR LOOKS VERY LOW. THE DAILY DETAILS... WED: WARM SECTOR. BREEZY AND WARMER BY 7-10F. WED NGT: A STRONG LLJ WILL DEVELOP /55-60 KTS/ WITH LOW-LVL WINDS VEERING TO THE SW. THIS WILL ADVECT AN EML ONTO THE PLAINS... IMPOSING A SUBSTANTIAL CAP. THU: WARM SECTOR. VERY WARM. ADD ANOTHER 3-7F TO WED AND THIS WILL PUT HIGHS 10F ABOVE NORMAL. HIGHS IN THE LWR 90S LOOK LIKE A GOOD BET OVER N-CNTRL KS. THU NGT: SOME ISOLATED HIGH-BASED SHWRS/TSTMS ARE POSSIBLE. THIS REALLY DEPENDS ON WHERE THE LLJ CORE SETS UP. THE EC IS FURTHER N THAN THE GFS AND NAM. IF SHWRS/TSTMS DEVELOP RAINFALL AMTS WILL BE VERY LIGHT. FRI: WARM SECTOR...BUT THE FRONT THREATENS THE NW FRINGE OF THE FCST AREA DURING PEAK HEATING. MOST OF THE FCST AREA SHOULD REMAIN DRY FOR MOST OF THE DAY. PCPN AND CLOUDS WILL BE MOST EXTENSIVE BEHIND THE FRONT WHICH SHOULD RESULT IN A SUBSTANTIAL TEMP CONTRAST ACROSS THE STATE. AHEAD OF THE FRONT EXPECT THE ATMS TO BE CAPPED. SCT TSTMS SHOULD ONLY ERUPT IN THE IMMEDIATE VICINITY OF THE FRONT IN THE LATE AFTN. SEVERE?: PROBABLY NOT BUT IF THERE IS A THREAT IS LOOKS VERY MARGINAL DUE TO WEAK INSTABILITY. HOWEVER...STRENGTH OF THE WIND FIELDS AND THE DRY SUB-CLOUD LAYER COULD SUPPORT SOME DECENT WINDS IF A STRONGER STORM OR TWO CAN DEVELOP. FRI NGT: COLD FRONTAL PASSAGE. THE SETUP LOOKS GOOD FOR SOME DECENT POST-FRONTAL RAINFALL IN SOME LOCATIONS. SAT: MUCH COOLER! PROBABLY 20F COOLER THAN FRI. IN FACT...WITH THE UPR TROF MOVING THRU...BELIEVE FUTURE FCSTS WILL END UP LOWERING HIGHS ANOTHER 5F OR SO. CONSENSUS OF 2M TEMPS CURRENTLY OFFERS 57F AT ORD AND 67F AT BELOIT. NOT MUCH DIFF FROM THE 12Z/18Z CYCLES. SWEATSHIRTS AND JACKETS MAY BE NEEDED FOR OUTDOOR ACTIVITIES. CLOUDY TO START WITH A COUPLE LEFTOVER SHWRS OR SOME PATCHY DRZL. CLEARING PROGRESSES FROM W TO E IN THE AFTN. SUN-MON: BACK TO NICER WX. TEMPS REBOUND AND WITH LOW PRES MOVING THRU THE CANADIAN ROCKIES...A LEE-SIDE TROF WILL DEVELOP AND MAY ACTUALLY PROGRESS THRU THE FCST AREA WITH AN ATTENDANT THERMAL RIDGE. HIGHS SHOULD BE BACK INTO THE LOW-MID 70S SUN AND UPR 70S-80 MON? && .AVIATION...(FOR THE 12Z KGRI TAF THROUGH 12Z WEDNESDAY MORNING) ISSUED AT 700 AM CDT TUE SEP 24 2013 ALTHOUGH CONFIDENCE REMAINS HIGH IN VFR VISIBILITY THROUGH THE NEXT 24 HOURS...CEILING TRENDS WILL CONTINUE TO BE A CHALLENGE ESPECIALLY THROUGH THE FIRST 6 HOURS TODAY...AS THE LOCAL AREA IS CURRENTLY A MIXED BAG OF CLEAR SKIES INTERSPERSED WITH PASSING BATCHES OF LOW VFR...MVFR AND EVEN IFR LOW CLOUDS. BASED ON LATEST OBS AND SATELLITE TRENDS...WENT AHEAD AND INTRODUCED PREVAILING HIGHER MVFR CEILING THROUGH THE NEXT 6 HOURS...WITH A TEMPO GROUP FOR LOWER MVFR CEILING FOR THE FIRST 4 HOURS. SOMETIME EARLY-MID AFTERNOON...ANTICIPATE ANY LOW CEILINGS TO SCATTER OUT OR MOVE OFF TO THE EAST....WITH FAIRLY HIGH CONFIDENCE IN NO WORSE THAN CLEAR/MOSTLY CLEAR SKIES DURING AT LEAST THE FINAL 15 HOURS OF THE PERIOD. AS FOR SURFACE WINDS...STEADY NORTHWEST BREEZES WILL PERSIST THROUGH THE NEXT SEVERAL HOURS...WITH GUST POTENTIAL TO AT LEAST 22KT OR HIGHER LASTING THROUGH MID-DAY BEFORE STEADILY DIMINISHING DURING THE AFTERNOON...AND BECOMING LIGHT/VARIABLE TONIGHT. && .HYDROLOGY... ISSUED AT 438 AM CDT TUE SEP 24 2013 OVERALL LITTLE CHANGE IN EXPECTATIONS OVERNIGHT REGARDING PLATTE RIVER FLOODING/FLOODING POTENTIAL. WE CONTINUE TO ADVERTISE TWO OFFICIAL FLOOD WARNINGS AT THIS TIME...ONE FOR THE RIVER GAGE NEAR COZAD...WHICH COVERS THE PLATTE RIVER REACH ACROSS DAWSON COUNTY INTO FAR WESTERN BUFFALO...AND A SECOND FOR THE GAGE NEAR KEARNEY...WHICH COVERS THE REACH OF THE RIVER ALONG THE BUFFALO/PHELPS/KEARNEY COUNTY LINE...AND THEN ACROSS THE MAJORITY OF HALL COUNTY. ALTHOUGH THE LATEST MISSOURI BASIN RIVER FORECAST CENTER (MBRFC) FORECAST TAKES THE GRAND ISLAND GAGE A FEW MILES EAST OF TOWN BARELY INTO MINOR FLOOD STAGE WEDNESDAY NIGHT...WE CONTINUE TO HOLD OFF ON A FORMAL FLOOD WARNING FOR THIS EASTERN HALL COUNTY AREA AND POINTS EAST...MAINLY TO GIVE A BIT MORE TIME TO FINE TUNE THE FORECAST BASED ON UPSTREAM BEHAVIOR AT THE COZAD AND KEARNEY GAGES...AND ALSO THE OVERTON GAUGE WHICH IS NOT AN OFFICIAL FORECAST POINT. OVER THE PAST SEVERAL HOURS...THE GAGE ALONG THE NORTH CHANNEL AT COZAD FINALLY REACHED MINOR FLOOD STAGE OF 6.5 FT AT 9 PM MONDAY EVENING...AND HAS CONTINUED A STEADY CLIMB TO JUST OVER 7.2 FT AS OF 330 AM. AS A RESULT...THE CREST WHICH IS EXPECTED TO OCCUR SOMETIME TODAY HAS BEEN NUDGED UPWARD TO 7.3 FT. THIS IS ANTICIPATED TO BE A PROLONGED CREST WITH ONLY A VERY SLOW FALL TO BELOW FLOOD STAGE BY SOMETIME FRIDAY. MEANWHILE...THE LATEST OVERNIGHT TRENDS ON THE OVERTON AND KEARNEY GAGES CONTINUE TO REFLECT VERY SLOW RISES...AND IT IS YET TO BE SEEN WHETHER THE KEARNEY GAGE IN FACT CAN BREACH THE MINOR FLOOD STAGE OF 6.0 FT BY LATE THIS MORNING AS THE LATEST FORECAST SUGGESTS. AT ANY RATE...A CREST OF 7.2 FT CONTINUES TO BE FORECAST FOR KEARNEY ON WEDNESDAY...AND AGAIN THIS WILL BE A PROLONGED CREST WITH A VERY SLOW FALL...POSSIBLY REMAINING IN FLOOD STAGE THROUGH THE END OF THE MONTH. PLEASE NOTE ONLY MINOR FLOOD STAGE...AND NOT MODERATE/MAJOR CATEGORIES...ARE ANTICIPATED ALONG THE AFOREMENTIONED FORECAST POINTS WITHIN THE NWS HASTINGS CWA...AND THUS THE VAST MAJORITY OF IMPACTS SHOULD REMAIN CONFINED TO THE IMMEDIATE LOWLAND AREAS NEAR THE RIVER CHANNEL/S. THESE RIVER FORECASTS ARE UPDATED REGULARLY PER COORDINATION BETWEEN MBRFC AND NWS HASTINGS...AND MINOR TWEAKS IN CREST HEIGHT AND TIMING REMAIN LIKELY OVER THE COMING DAYS. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...PFANNKUCH SHORT TERM...PFANNKUCH LONG TERM...HALBLAUB AVIATION...PFANNKUCH HYDROLOGY...PFANNKUCH
AREA FORECAST DISCUSSION
NWS HASTINGS NE
439 AM CDT TUE SEP 24 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 438 AM CDT TUE SEP 24 2013 ALTHOUGH MOST IF NOT ALL OF THE CWA IS LOOKING AT A DRY AND FAIRLY UNEVENTFUL UPCOMING 24 HOURS...ESPECIALLY THE DAYTIME HOURS HAVE BECOME TRICKIER-THAN-EXPECTED MAINLY REGARDING THE EVOLUTION OF SKY COVER/TEMPERATURES...AS LOW CLOUDS COULD BE STUBBORNLY SLOW TO DEPART MAINLY WITHIN THE EASTERN 1/2 OF THE CWA...BRINGING 5+ DEGREE TEMP BUST POTENTIAL VERY MUCH INTO PLAY. 08Z OBJECTIVE SURFACE ANALYSIS HIGHLIGHTS A SLOWLY-WEAKENING 1004 MILLIBAR LOW PRESSURE CENTER...CENTERED OVER THE CLAY/FILLMORE COUNTY AREA...WHILE IN ITS WAKE THE LEADING EDGES OF HIGH PRESSURE AROUND 1016MB HAS WORKED INTO THE NEB PANHANDLE. WITH THE MAJORITY OF THE CWA POSITIONED BEHIND THE DEPARTING LOW...EARLY MORNING BREEZES ARE MAINLY FROM THE WEST-NORTHWEST...WITH THE STRONGEST SPEEDS WITH GUSTS OF 20+ MPH FOCUSED ACROSS THE SOUTHWESTERN HALF OF THE AREA...WITH LIGHTER SPEEDS STILL HOLDING ON FOR AT LEAST A FEW MORE HOURS WITHIN MUCH OF THE NORTHEAST 1/2. ALOFT...WATER VAPOR IMAGERY AND SHORT TERM MODEL DATA CLEARLY REVEAL A WELL- DEFINED...NOT QUITE VERTICALLY STACKED LOW PRESSURE SYSTEM DEPARTING EASTWARD ACROSS THE EASTERN 1/4 OF NEB...WITH A CLOSED 500MB CIRCULATION CENTERED NEAR NORFOLK. AS A RESULT...THE PRIMARY MID LEVEL CONVERGENCE/DEFORMATION ZONE AT THIS HOUR IS FOCUSING WIDESPREAD MAINLY LIGHT RAIN 50+ MILES NORTHEAST OF THE CWA. CLOUD-WISE...11-3.9 MICRON SATELLITE IMAGERY DEPICTS A FAIRLY COMPLEX AND EVER-CHANGING MIXTURE OF CLEAR SKIES ALONG WITH PASSING BATCHES OF MID CLOUDS AND LOW STRATUS. WHILE MOST OF THESE LOWER CEILINGS WITHIN THE CWA ARE AT/ABOVE 1500 FT...A CORRIDOR OF LOWER CEILINGS BETWEEN 500-1000 FT SEEMS TO BE LURKING JUST NORTHWEST OF THE CWA ALONG A BROKEN BOW-AINSWORTH AXIS...WITH THESE LOW CLOUDS POSSIBLY EVEN SUPPORTING SOME PATCHY LIGHT DRIZZLE. TEMP-WISE...MOST OF THE CWA APPEARS HEADED FOR OVERNIGHT LOWS IN THE MID 50S...WITH ANY LOW 50S/UPPER 40S MOST FAVORED IN FAR WESTERN COUNTIES. AS THE EARLY MORNING/DAYTIME HOURS WEAR ON...THE BIG PICTURE ALOFT INVOLVES THE MID LEVEL SHORTWAVE TROUGH/ASSOCIATED CLOSED LOW CONTINUING ITS STEADY TREK EASTWARD...WITH THE 500MB CIRCULATION CENTER INTO SOUTHWEST IA BY 18Z...AND THEN OVER NORTH CENTRAL MO BY 00Z/7PM. AS THIS LOW DEPARTS...A BROAD AREA OF SHORTWAVE RIDGING AND ASSOCIATED HEIGHT RISES WILL OVERSPREAD THE CENTRAL PLAINS. AT THE SURFACE...THE LOW PRESSURE CENTER CURRENTLY OVER SOUTHEAST NEB WILL CONTINUE TO WEAKEN AS IT SLIDES INTO CENTRAL MO OVER THE COURSE OF THE DAY...ALLOWING A MODEST RIDGE AXIS TO BUILD INTO THE LOCAL AREA WITH TIME AND RELAX THE SURFACE PRESSURE GRADIENT. HOWEVER...BREEZES WILL STILL BE FAIRLY ELEVATED FOR MUCH OF THE DAY TODAY...LARGELY OWING TO MIXING CLIMBING UP TO AROUND 850MB...WHERE AN ENHANCED CORRIDOR OF 30-40KT NORTHERLY WINDS WILL LINGER THROUGH MID-DAY BEFORE STEADILY WEAKENING IN THE AFTERNOON. THE NET RESULT WILL BE SUSTAINED NORTH-NORTHWEST WIND SPEEDS 15-20 MPH WITH GUSTS 25+ MPH THROUGH THIS MORNING...BEFORE DIMINISHING TO MORE SO SUSTAINED 10-15 MPH SPEEDS THIS AFTERNOON...AND ONLY 5-10 MPH CLOSER TO SUNSET. AS FOR PRECIP CHANCES...ALTHOUGH RADAR TRENDS AND SHORT TERM MODEL DATA INCLUDING THE HRRR PRETTY STRONGLY SUGGEST THAN ANY RISK OF MEASURABLE LIGHT RAIN SHOULD BE OVER BY 12Z...WENT AHEAD AND LINGERED A TOKEN 20 POP IN THE EXTREME NORTHEAST NANCE/MERRICK/POLK AREA THROUGH 15Z IN CASE SOMETHING MANAGES TO STILL WRAP AROUND THE BACK SIDE OF THE LOW. THE BIG CHALLENGE TODAY SEEMS TO BE CENTERED AROUND SKY COVER. 24 HOURS AGO...IT WAS ASSUMED THAT MID LEVEL CLOUDS WOULD QUICKLY MOVE OFF EAST OF THE CWA TODAY WITH THE PARENT SYSTEM. HOWEVER...LATEST SATELLITE AND SHORT TERM MODEL DATA INCLUDING THE HRRR LOW CLOUD PRODUCT NOW SUGGEST THAT THE AREAL COVERAGE OF LOW STRATUS MAY IN FACT INCREASE BEFORE SUNRISE FROM THE NORTHWEST...AND THEN POSSIBLY HANG VERY STUBBORNLY MAINLY ACROSS THE CENTRAL/EASTERN CWA EVEN INTO THE AFTERNOON HOURS. ALTHOUGH HAVE NOT BOUGHT FULL-BORE INTO THE VERY PESSIMISTIC RUC/HRRR SOLUTIONS REGARDING LOW CLOUDS TODAY...DID INCREASE SKY COVER PERCENTAGES VERSUS PREVIOUS...AND ALSO DELAYED THE WEST-EAST CLEARING TREND. HOWEVER...PLEASE NOTE THAT ESPECIALLY EASTERN COUNTIES ALONG/NEAR HIGHWAY 81 MAY REALLY STRUGGLE TO SEE MUCH SUN UNTIL MAYBE LATE AFTERNOON...AND DAY SHIFT MAY HAVE TO MAKE SOME PRETTY NOTICEABLE ADJUSTMENTS TO SKY COVER AND RESULTANT HIGH TEMPS. FOR NOW THOUGH...OPTED TO ONLY SHAVE 1-2 DEGREES OFF PREVIOUS HIGHS IN MOST AREAS...RANGING FROM LOW 70S FAR EAST TO UPPER 70S FAR SOUTHWEST...AND AROUND 73 TRI- CITIES. IF CLOUDS ARE SLOW TO DEPART HOWEVER...SOME EASTERN AREAS MAY STRUGGLE TO LEAVE THE 60S. ON ONE FINAL DAYTIME NOTE...ALTHOUGH HAVE DEWPOINTS DROPPING INTO THE LOW-MID 40S ACROSS MUCH OF THE WESTERN CWA DURING THE AFTERNOON...THESE VALUES ARE NOT QUITE AS LOW AS ANTICIPATED 24 HOURS AGO...AND THIS KEEPS ANY AFTERNOON RELATIVE HUMIDITY VALUES AS LOW AS 25-30 PERCENT CONFINED TO MAINLY JUST THE FURNAS COUNTY AREA. FOR THE EVENING/NIGHT 00Z-12Z PERIOD...WILL RUN WITH THE ASSUMPTION THAT EVEN IF LOW STRATUS LINGERS QUITE AWHILE INTO THE AFTERNOON IN SOME AREAS...THAT IT SHOULD BE SAFELY EAST OF THE CWA BY SUNSET...THUS RESULTING IN A CLEAR OVERNIGHT AREA-WIDE WITH ESSENTIALLY ZERO RISK OF PRECIP. ON THE BIG PICTURE...THE HEART OF THE AFOREMENTIONED MID/UPPER LEVEL SHORTWAVE RIDGE AXIS WILL PASS DIRECTLY OVER THE CWA...VERY SIMILAR TO LAST FRIDAY NIGHT. ALSO SIMILAR TO LAST FRIDAY AT THE SURFACE...VERY LIGHT/VARIABLE BREEZES IN THE EVENING WILL GRADUALLY GIVE WAY TO LIGHT SOUTHEAST BREEZES LATER IN THE NIGHT AS THE SURFACE RIDGE AXIS DRIFTS EASTWARD ACROSS THE CWA. HOWEVER...COMPARED TO 24 HOURS AGO IT NOW APPEARS THAT DEWPOINTS WILL NOT DROP OFF QUITE AS FAR...AND THUS GUIDANCE/MODELS HAVE TRENDED A FEW DEGREES MILDER FOR OVERNIGHT LOWS. AS A RESULT...NUDGED UP LOWS 1-2 DEGREES MOST AREAS VERSUS PREVIOUS...AIMING MOST OF THE CWA BETWEEN 50-53...BUT WITH PREDOMINANTLY MID-UPPER 40S IN A FEW OF THE FAR WESTERN NORTHERN/COUNTIES. DESPITE THE LIGHT OVERNIGHT BREEZES...AM NOT EXPECTING IMPACTFUL FOG TO BE AN ISSUE...ALTHOUGH SOME VERY LIGHT FOG/HAZE IS PROBABLY NOT OUT OF THE QUESTION...BUT IS ALSO NOT WORTH ADVERTISING IN THE FORECAST. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 438 AM CDT TUE SEP 24 2013 PATTERN: THE CPC OBSERVED H5 HGT ANOMALY TOOLS SHOW THAT THE LOW FREQUENCY /LGWV/ FLOW OF THE PAST 90 DAYS LARGELY REMAINS IN PLACE OVER THE NRN HEMISPHERE. HOWEVER...WE HAVE RECENTLY SEEN AMPLIFICATION ESPECIALLY WITH THE ERN PAC TROF. OTHER ADJUSTMENTS SHOW THAT THE +HGT ANOMALY WHICH HAS RESIDED OVER WRN N AMERICA HAS SHIFT TO THE E...ALLOWING THE TEMPORARY ESTABLISHMENT OF A WRN N AMERICA TROF. THIS TROF WILL ONLY BE WITH US THIS WEEK AND OFFERS ONE MORE SHOT AT DECENT RAINFALL. THE NAO HAS TURNED SHARPLY NEGATIVE AS THE PERSISTENT -HGT ANOMALY OVER GREENLAND HAS BEEN REPLACED WITH +HGT ANOMALIES. THIS COMBINED WITH THE A PAIR OF STORMS CROSSING THE NRN PAC WILL RETURN RIDGING TO WRN N AMERICA THIS WEEKEND. SO THE BOTTOM LINE IS...EXCEPT FOR A BRIEF WINDOW THU NGT-FRI...DRY WX WILL CONT. TEMPS WILL BE VARIABLE BUT PROBABLY AVERAGE PRETTY CLOSE TO NORMAL OVER THE NEXT 10 DAYS. ALOFT: SW FLOW WILL DEVELOP OVER THE CNTRL PLAINS WED AND CONT THRU FRI...AS THE WRN USA TROF FULLY RELOADS. CYCLOGENESIS WILL OCCUR THU...WITH THE MAIN UPR LOW HEADING N INTO CANADA. THE MAIN UPR TROF WILL BE LEFT BEHIND AND BEGIN LIFTING NE...CROSSING THE CNTRL PLAINS SAT. NW FLOW FOLLOWS SUN-MON BUT THERE IS DISAGREEMENT/UNCERTAINTY IN THE AMPLITUDE OF THE RIDGE MOVING INTO THE W. SFC: A PAC COLD FRONT WILL EXTEND FROM THE NRN ROCKIES TO CNTRL CA WED...WITH A LEE-SIDE TROF IN PLACE. THIS FRONT WILL ADVANCE E AND EMERGE ONTO THE PLAINS BY DAWN THU. HOWEVER...THE SRN PORTION WILL REMAIN STATIONARY DUE TO MINIMAL MOVEMENT OF THE BASE OF THE TROF. THE SLOW EJECTION OF THE TROF MEANS THE FWD PROGRESS OF THE FRONT WILL BE SLOW. WRN USA HIGH PRES BUILDS IN SAT THRU MON. WITH SW FLOW ALOFT ON BOTH SIDES OF THIS FRONT...IT WILL HAVE AN ANABATIC CHARACTER. THE SLOW MOVEMENT OFFERS THE OPPORTUNITY FOR ENTRAINMENT OF GULF MSTR. WE ARE SEEING A NARROW RIBBON OF MSTR FCST TO SURGE NWD FRI...WITH PW NEARING 1.6". HAZARDS: NOTHING SUBSTANTIAL...BUT THERE IS A LATE-WEEK THUNDER THREAT. RISK OF SVR LOOKS VERY LOW. THE DAILY DETAILS... WED: WARM SECTOR. BREEZY AND WARMER BY 7-10F. WED NGT: A STRONG LLJ WILL DEVELOP /55-60 KTS/ WITH LOW-LVL WINDS VEERING TO THE SW. THIS WILL ADVECT AN EML ONTO THE PLAINS... IMPOSING A SUBSTANTIAL CAP. THU: WARM SECTOR. VERY WARM. ADD ANOTHER 3-7F TO WED AND THIS WILL PUT HIGHS 10F ABOVE NORMAL. HIGHS IN THE LWR 90S LOOK LIKE A GOOD BET OVER N-CNTRL KS. THU NGT: SOME ISOLATED HIGH-BASED SHWRS/TSTMS ARE POSSIBLE. THIS REALLY DEPENDS ON WHERE THE LLJ CORE SETS UP. THE EC IS FURTHER N THAN THE GFS AND NAM. IF SHWRS/TSTMS DEVELOP RAINFALL AMTS WILL BE VERY LIGHT. FRI: WARM SECTOR...BUT THE FRONT THREATENS THE NW FRINGE OF THE FCST AREA DURING PEAK HEATING. MOST OF THE FCST AREA SHOULD REMAIN DRY FOR MOST OF THE DAY. PCPN AND CLOUDS WILL BE MOST EXTENSIVE BEHIND THE FRONT WHICH SHOULD RESULT IN A SUBSTANTIAL TEMP CONTRAST ACROSS THE STATE. AHEAD OF THE FRONT EXPECT THE ATMS TO BE CAPPED. SCT TSTMS SHOULD ONLY ERUPT IN THE IMMEDIATE VICINITY OF THE FRONT IN THE LATE AFTN. SEVERE?: PROBABLY NOT BUT IF THERE IS A THREAT IS LOOKS VERY MARGINAL DUE TO WEAK INSTABILITY. HOWEVER...STRENGTH OF THE WIND FIELDS AND THE DRY SUB-CLOUD LAYER COULD SUPPORT SOME DECENT WINDS IF A STRONGER STORM OR TWO CAN DEVELOP. FRI NGT: COLD FRONTAL PASSAGE. THE SETUP LOOKS GOOD FOR SOME DECENT POST-FRONTAL RAINFALL IN SOME LOCATIONS. SAT: MUCH COOLER! PROBABLY 20F COOLER THAN FRI. IN FACT...WITH THE UPR TROF MOVING THRU...BELIEVE FUTURE FCSTS WILL END UP LOWERING HIGHS ANOTHER 5F OR SO. CONSENSUS OF 2M TEMPS CURRENTLY OFFERS 57F AT ORD AND 67F AT BELOIT. NOT MUCH DIFF FROM THE 12Z/18Z CYCLES. SWEATSHIRTS AND JACKETS MAY BE NEEDED FOR OUTDOOR ACTIVITIES. CLOUDY TO START WITH A COUPLE LEFTOVER SHWRS OR SOME PATCHY DRZL. CLEARING PROGRESSES FROM W TO E IN THE AFTN. SUN-MON: BACK TO NICER WX. TEMPS REBOUND AND WITH LOW PRES MOVING THRU THE CANADIAN ROCKIES...A LEE-SIDE TROF WILL DEVELOP AND MAY ACTUALLY PROGRESS THRU THE FCST AREA WITH AN ATTENDANT THERMAL RIDGE. HIGHS SHOULD BE BACK INTO THE LOW-MID 70S SUN AND UPR 70S-80 MON? && .AVIATION...(FOR THE 06Z KGRI TAF THROUGH 06Z TUESDAY NIGHT) ISSUED AT 1230 AM CDT TUE SEP 24 2013 ALTHOUGH CONFIDENCE REMAINS HIGH IN VFR VISIBILITY THROUGH THE NEXT 24 HOURS...CEILING TRENDS COULD BE A CHALLENGE ESPECIALLY DURING THE NEXT 12 HOURS...AS THE LOCAL AREA IS CURRENTLY A MIXED BAG OF CLEAR SKIES INTERSPERSED WITH PASSING BATCHES OF LOW VFR...MVFR AND POSSIBLY EVEN IFR LOW CLOUDS. STRONGLY CONSIDERED ADDING A PREVAILING MVFR CEILING FOR SEVERAL HOURS CENTERED BETWEEN 12Z-18Z...BUT GIVEN LOW CONFIDENCE IN VARIOUS MODEL SOLUTIONS AND OBSERVATIONAL TRENDS WILL ONLY RUN WITH A TEMPO MVFR MENTION FROM 10Z-14Z FOR NOW...AND FURTHER EVALUATE PREVAILING MVFR POTENTIAL WITH THE NEXT ROUTINE TAF ISSUANCE. IN GENERAL HOWEVER...ANTICIPATE AT LEAST LOW-VFR CEILINGS TO REMAIN FAIRLY PREVALENT THROUGH MID-DAY BEFORE LIFTING AND GRADUALLY SCATTERING OUT DURING THE AFTERNOON HOURS...WITH HIGH CONFIDENCE IN NO WORSE THAN CLEAR/MOSTLY CLEAR SKIES DURING AT LEAST THE FINAL 9 HOURS OF THE PERIOD. AS FOR SURFACE WINDS...A PRONOUNCED SHIFT TO NORTHWEST BREEZES WILL ARRIVE AT KGRI WITHIN THE NEXT FEW HOURS BEHIND A PASSING COLD FRONT...WITH GUST POTENTIAL TO AT LEAST 22KT OR HIGHER LASTING THROUGH MID-DAY BEFORE STEADILY DIMINISHING DURING THE AFTERNOON AND BECOMING LIGHT/VARIABLE FOR TUESDAY EVENING. && .HYDROLOGY... ISSUED AT 438 AM CDT TUE SEP 24 2013 OVERALL LITTLE CHANGE IN EXPECTATIONS OVERNIGHT REGARDING PLATTE RIVER FLOODING/FLOODING POTENTIAL. WE CONTINUE TO ADVERTISE TWO OFFICIAL FLOOD WARNINGS AT THIS TIME...ONE FOR THE RIVER GAGE NEAR COZAD...WHICH COVERS THE PLATTE RIVER REACH ACROSS DAWSON COUNTY INTO FAR WESTERN BUFFALO...AND A SECOND FOR THE GAGE NEAR KEARNEY...WHICH COVERS THE REACH OF THE RIVER ALONG THE BUFFALO/PHELPS/KEARNEY COUNTY LINE...AND THEN ACROSS THE MAJORITY OF HALL COUNTY. ALTHOUGH THE LATEST MISSOURI BASIN RIVER FORECAST CENTER (MBRFC) FORECAST TAKES THE GRAND ISLAND GAGE A FEW MILES EAST OF TOWN BARELY INTO MINOR FLOOD STAGE WEDNESDAY NIGHT...WE CONTINUE TO HOLD OFF ON A FORMAL FLOOD WARNING FOR THIS EASTERN HALL COUNTY AREA AND POINTS EAST...MAINLY TO GIVE A BIT MORE TIME TO FINE TUNE THE FORECAST BASED ON UPSTREAM BEHAVIOR AT THE COZAD AND KEARNEY GAGES...AND ALSO THE OVERTON GAUGE WHICH IS NOT AN OFFICIAL FORECAST POINT. OVER THE PAST SEVERAL HOURS...THE GAGE ALONG THE NORTH CHANNEL AT COZAD FINALLY REACHED MINOR FLOOD STAGE OF 6.5 FT AT 9 PM MONDAY EVENING...AND HAS CONTINUED A STEADY CLIMB TO JUST OVER 7.2 FT AS OF 330 AM. AS A RESULT...THE CREST WHICH IS EXPECTED TO OCCUR SOMETIME TODAY HAS BEEN NUDGED UPWARD TO 7.3 FT. THIS IS ANTICIPATED TO BE A PROLONGED CREST WITH ONLY A VERY SLOW FALL TO BELOW FLOOD STAGE BY SOMETIME FRIDAY. MEANWHILE...THE LATEST OVERNIGHT TRENDS ON THE OVERTON AND KEARNEY GAGES CONTINUE TO REFLECT VERY SLOW RISES...AND IT IS YET TO BE SEEN WHETHER THE KEARNEY GAGE IN FACT CAN BREACH THE MINOR FLOOD STAGE OF 6.0 FT BY LATE THIS MORNING AS THE LATEST FORECAST SUGGESTS. AT ANY RATE...A CREST OF 7.2 FT CONTINUES TO BE FORECAST FOR KEARNEY ON WEDNESDAY...AND AGAIN THIS WILL BE A PROLONGED CREST WITH A VERY SLOW FALL...POSSIBLY REMAINING IN FLOOD STAGE THROUGH THE END OF THE MONTH. PLEASE NOTE ONLY MINOR FLOOD STAGE...AND NOT MODERATE/MAJOR CATEGORIES...ARE ANTICIPATED ALONG THE AFOREMENTIONED FORECAST POINTS WITHIN THE NWS HASTINGS CWA...AND THUS THE VAST MAJORITY OF IMPACTS SHOULD REMAIN CONFINED TO THE IMMEDIATE LOWLAND AREAS NEAR THE RIVER CHANNEL/S. THESE RIVER FORECASTS ARE UPDATED REGULARLY PER COORDINATION BETWEEN MBRFC AND NWS HASTINGS...AND MINOR TWEAKS IN CREST HEIGHT AND TIMING REMAIN LIKELY OVER THE COMING DAYS. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM...PFANNKUCH LONG TERM...HALBLAUB AVIATION...PFANNKUCH HYDROLOGY...PFANNKUCH
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1236 AM CDT TUE SEP 24 2013 .UPDATE... ISSUED AT 1230 AM CDT TUE SEP 24 2013 PRIMARY CHANGE WITH THE LATEST SHORT-TERM UPDATE THROUGH THE REST OF THE OVERNIGHT HOURS WAS TO RELEGATE ANY MENTION OF ISOLATED/SCATTERED SHOWERS TO LOCATIONS GENERALLY NORTH OF A LOUP CITY-CENTRAL CITY-YORK LINE...AND EVEN AT THAT THE MAJORITY OF THAT AREA MAY BE LUCKY TO SEE MORE THAN A NON-MEASURABLE SPRINKLE THROUGH THE REST OF THE NIGHT PER LATEST RADAR TRENDS. OTHERWISE...SKY COVER WILL BE RATHER COMPLEX THROUGH THE NEXT 12 HOURS OR SO...WITH AREAS OF CLEAR SKIES INTERSPERSED WITH MIGRATING BATCHES OF LOW AND MID LEVEL CLOUDS. IT IS STARTING TO APPEAR HOWEVER THAT THE POST-SUNRISE TUESDAY MORNING HOURS COULD START OUT CLOUDIER THAN EARLIER EXPECTED ACROSS PARTS OF THE CENTRAL/EASTERN CWA PER LOW LEVEL RELATIVE HUMIDITY PROGS FROM THE NAM AND ALSO THE HRRR LOW LEVEL CLOUD COVER PRODUCT...AND THESE TRENDS WILL CONTINUE TO BE MONITORED AND DISCUSSED IN MORE DETAIL IN THE PRIMARY MORNING DISCUSSION. && .SHORT TERM...(THIS EVENING THROUGH TUESDAY) ISSUED AT 410 PM CDT MON SEP 23 2013 PRIMARY FORECAST CONCERN LIES WITH PRECIPITATION CHANCES. NOT HARD TO PICK OUT THE FEATURES OF INTEREST THIS AFTERNOON...WITH WV SATELLITE IMAGERY SHOWING A WOUND UP UPPER LEVEL LOW PRESSURE SYSTEM GRADUALLY MAKING ITS WAY THROUGH WRN PORTIONS OF NEB AND FAR NWRN KS. ITS A WELL STACKED SYSTEM...AND THE SFC LOW IS IN THE SAME AREA...WITH SFC OBS SHOWING THE MAIN FRONTAL BOUNDARY EXTENDING NORTH THROUGH CHERRY CNTY NEB. THE NARROW BAND OF SHOWERS/ISO THUNDER DRIVEN BY UPPER LEVEL JET ENERGY IS FINALLY STARTING TO WORK ITS WAY THROUGH/OUT OF ERN PORTIONS OF THE CWA...BUT THE NEXT ROUND OF PRECIPITATION IS GEARING UP...ASSOCIATED WITH INCREASED LIFT WITH THE LOW ITSELF. AT THE SURFACE...WITH THE TIGHTENED PRESSURE GRADIENT SET UP AHEAD OF THE APPROACHING LOW...AND WITH INCREASED MIXING POTENTIAL...IT HAS BEEN A BREEZY AFTERNOON. THIS HAS ESP BEEN THE CASE ACROSS WRN/CENTRAL PORTIONS OF OUR NC KS COUNTIES /MAINLY SMITH CENTER/...WHICH SAT UNDER LESS CLOUD COVER THAN THE REST OF THE CWA...WAS ABLE TO TAP INTO THAT BETTER POTENTIAL FOR STRONGER WINDS...AND AT TIMES BOUNCE AROUND/HIT ADV CRITERIA. WITH THE FRONT APPROACHING AND THE NEXT BATCH OF CLOUDS STARTING TO MOVE INTO THAT AREA...WHICH SHOULD KEEP WINDS DOWN A BIT. THE MAIN FOCUS FOR THE SHORT TERM IS REALLY OVER THE NEXT 6-12 HRS...AS THIS UPPER LEVEL LOW CONTINUES TO DRIFT E/NE THROUGH THE AREA. SPC MESO PAGE SHOWING AN AREA OF INCREASED LOWER LEVEL LAPSE RATES OVER WRN PORTIONS OF THE CWA AND INTO WRN NEB/KS...THOUGH OVERALL INSTABILITY IS PRETTY WEAK. JUST TO THE WEST OF THE CWA...VIS SAT SHOWS A NARROW AREA WHERE THERE HAS BEEN A BIT MORE SUN...AND INSTABILITY/LAPSE RATES VALUES A TOUCH HIGHER THERE. THIS IS LOCATED IN THE SAME AREA AS THE MAIN LOW/SFC BOUNDARY...AND RECENT RADAR TRENDS HAVE SHOWN MORE CONVECTIVE ACTIVITY/LIGHTNING STRIKES THERE...VS THE MORE SHOWER ACTIVITY MOVING INTO THE CWA. THINGS WILL BECOME MORE STABILIZED...BUT CANT COMPLETELY RULE OUT A FEW RUMBLES OF THUNDER WITH THE SYSTEM MOVING RIGHT THROUGH. EVENTUALLY THE MAIN SFC BOUNDARY WILL PUSH THROUGH...WITH MODELS IN DECENT AGREEMENT SHOWING THE FRONT STARTING TO MOVE INTO THE WEST ARND 00Z...AND BY 12Z TOMORROW IS ACROSS FAR ERN PORTIONS OF THE CWA. EXPECTING THAT THE NORTHWESTERLY WINDS BEHIND THE FRONT BUILDING INTO THE CWA WILL BE ON THE GUSTY SIDE...BUT NOT AS GUSTY AS IT MIGHT HAVE BEEN HAD IT OCCURRED DURING THE DAYTIME HOURS. SPEEDS IN THE 15 TO 20 MPH RANGE AND GUSTS CLOSER TO 25 MPH WILL BE POSSIBLE...ESP ACROSS THE WRN THIRD TO HALF OF THE CWA. KEPT LINGERING POPS IN DURING THE 06-12Z PERIOD TONIGHT...AS MODELS HAVE BEEN FAIRLY CONSISTENT LATELY SHOWING THE SLOWER END TO THE PRECIPITATION. NOT EXPECTING ANYTHING THAT IS REMAINING DURING THIS TIME FRAME TO AMOUNT TO MUCH. SHORTWAVE RIDGING BUILDING IN FROM THE WEST WILL BRING DRY CONDITIONS DURING THE DAYTIME HOURS TOMORROW...AND IS LOOKING TO BE A DECENT DAY. WILL SEE WHATEVER CLOUDS MAY STILL BE LINGERING AROUND THE EAST IN THE MORNING FINALLY MOVE OFF...LEAVING MOSTLY CLEAR SKIES BEHIND. NORTHERLY WINDS THROUGH THE DAY MAY STILL BE ON THE GUSTY SIDE FOR AT LEAST PART OF THE DAY...BUT ARE EXPECTED TO START TO DIMINISH DURING THE AFTERNOON. OVERNIGHT LOWS TONIGHT ARE FORECAST TO FALL INTO THE 50S...WITH MID 70S GOING FOR HIGHS TOMORROW. .LONG TERM...(TUESDAY NIGHT THROUGH MONDAY) ISSUED AT 410 PM CDT MON SEP 23 2013 A WEAK RIDGE OF HIGH PRESSURE WILL SLIDE ACROSS THE LOCAL AREA WEDNESDAY AND THURSDAY...AHEAD OF THE NEXT UPPER LEVEL DISTURBANCE EXPECTED TO IMPACT THE CENTRAL PLAINS LATE IN THE WEEK. WHILE THE SURFACE PRESSURE GRADIENT WILL REMAIN FAIRLY RELAXED TUESDAY NIGHT...ALLOWING FOR MINIMAL MIXING AND GOOD RADIATIONAL COOLING...EXPECT WINDS TO ONCE AGAIN INCREASE ACROSS MUCH OF THE LOCAL AREA WEDNESDAY AND THURSDAY...AS THE PRESSURE GRADIENT WILL TIGHTEN AHEAD OF THE DEEPENING LOW ACROSS THE INTERMOUNTAIN WEST. THIS WILL RESULT IN A COUPLE OF BREEZY DAYS ACROSS THE LOCAL AREA BOTH WEDNESDAY AND THURSDAY AFTERNOONS WITH TEMPERATURES SURGING SEVERAL DEGREES ABOVE SEASONAL NORMS FOR LATE SEPTEMBER. THIS SURGE IN TEMPERATURES WILL BE FAIRLY SHORT LIVED...HOWEVER...AS INCREASING CLOUDS AND THE CHANCE FOR SHOWERS AND THUNDERSTORMS RETURN TO THE FORECAST LATE THURSDAY NIGHT...AS A COLD FRONT APPROACHES THE LOCAL AREA. WHILE THE GLOBAL MODELS BEGIN TO DIVERGE SOME WITH THEIR HANDLING OF THE MAIN UPPER LEVEL TROUGH THURSDAY NIGHT...WITH THE GEM/EC BEING A BIT LESS PROGRESSIVE WITH THE UPPER LEVEL LOW...WENT AHEAD AND MAINTAINED A CHANCE FOR SHOWERS AND THUNDERSTORMS ACROSS THE LOCAL AREA THURSDAY NIGHT THROUGH SATURDAY AFTERNOON...AS THE MAIN UPPER TROUGH WILL TAKE A COUPLE OF DAYS TO EXIT THE PLAINS. BEHIND THE MAIN COLD FRONT...WHICH IS EXPECTED LATE FRIDAY AFTERNOON OR NIGHT...EXPECT TEMPERATURES TO DROP OFF SEVERAL DEGREES...WITH HIGH TEMPERATURES STRUGGLING TO CLIMB OUT OF THE 60S IN MANY LOCATIONS... DESPITE THE ANTICIPATED CLEARING SKIES...SATURDAY AFTERNOON. THEREAFTER...DRY NORTHWESTERLY FLOW IS EXPECTED TO FOR THE LAST COUPLE OF DAYS OF THE EXTENDED FORECAST...WITH NO NOTABLE DISTURBANCES EMBEDDED IN THIS FLOW TO WARRANT THE MENTION OF ADDITIONAL CHANCES FOR PRECIPITATION. FOR THE FRIDAY NIGHT/EARLY SATURDAY TIME PERIOD WHEN PRECIP CHANCES LOOK THE GREATEST...INSTABILITY LOOKS MEAGER...AND DECIDED TO KEEP THUNDERSTORM ACTIVITY ISOLATED IN THE FORECAST FOR THE TIME BEING...WITH THE BEST CHANCE FOR ANY STRONG OR MORE WIDESPREAD THUNDERSTORM ACTIVITY EXPECTED TO LIE IN THE VICINITY OR JUST AHEAD OF THE FRONT FRIDAY NIGHT...GENERALLY ACROSS THE SOUTHEASTERN QUADRANT OF THE LOCAL AREA. && .AVIATION...(FOR THE 06Z KGRI TAF THROUGH 06Z TUESDAY NIGHT) ISSUED AT 1230 AM CDT TUE SEP 24 2013 ALTHOUGH CONFIDENCE REMAINS HIGH IN VFR VISIBILITY THROUGH THE NEXT 24 HOURS...CEILING TRENDS COULD BE A CHALLENGE ESPECIALLY DURING THE NEXT 12 HOURS...AS THE LOCAL AREA IS CURRENTLY A MIXED BAG OF CLEAR SKIES INTERSPERSED WITH PASSING BATCHES OF LOW VFR...MVFR AND POSSIBLY EVEN IFR LOW CLOUDS. STRONGLY CONSIDERED ADDING A PREVAILING MVFR CEILING FOR SEVERAL HOURS CENTERED BETWEEN 12Z-18Z...BUT GIVEN LOW CONFIDENCE IN VARIOUS MODEL SOLUTIONS AND OBSERVATIONAL TRENDS WILL ONLY RUN WITH A TEMPO MVFR MENTION FROM 10Z-14Z FOR NOW...AND FURTHER EVALUATE PREVAILING MVFR POTENTIAL WITH THE NEXT ROUTINE TAF ISSUANCE. IN GENERAL HOWEVER...ANTICIPATE AT LEAST LOW-VFR CEILINGS TO REMAIN FAIRLY PREVALENT THROUGH MID-DAY BEFORE LIFTING AND GRADUALLY SCATTERING OUT DURING THE AFTERNOON HOURS...WITH HIGH CONFIDENCE IN NO WORSE THAN CLEAR/MOSTLY CLEAR SKIES DURING AT LEAST THE FINAL 9 HOURS OF THE PERIOD. AS FOR SURFACE WINDS...A PRONOUNCED SHIFT TO NORTHWEST BREEZES WILL ARRIVE AT KGRI WITHIN THE NEXT FEW HOURS BEHIND A PASSING COLD FRONT...WITH GUST POTENTIAL TO AT LEAST 22KT OR HIGHER LASTING THROUGH MID-DAY BEFORE STEADILY DIMINISHING DURING THE AFTERNOON AND BECOMING LIGHT/VARIABLE FOR TUESDAY EVENING. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...PFANNKUCH SHORT TERM...ADO LONG TERM...SAR AVIATION...PFANNKUCH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
713 AM EDT TUE SEP 24 2013 .SYNOPSIS... A RIDGE OF HIGH PRESSURE SITTING OVER THE REGION WILL GRADUALLY WEAKEN TODAY AND TONIGHT. A LOW PRESSURE SYSTEM WILL CROSS THE SOUTHEAST STATES WEDNESDAY AND WEDNESDAY NIGHT... AS AN UPPER LEVEL TROUGH TRACKS ACROSS THE CAROLINAS. HIGH PRESSURE WILL BUILD BACK INTO THE REGION THURSDAY AND FRIDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 225 AM TUESDAY... FOR TODAY: RESIDUAL MOISTURE BENEATH THE SUBSIDENCE INVERSION ALOFT AND MOIST ISENTROPIC UPGLIDE AROUND 295K HAS RESULTED IN AREALLY EXPANDING STRATUS OVER CENTRAL/WRN VA AND WRN NC THIS MORNING... QUICKLY SPREADING INTO THE NRN AND WRN PORTIONS OF THE FORECAST AREA... WHICH WAS NOT DEPICTED WELL AT ALL BY THE NAM/GFS MODELS. TRENDS SUPPORT A CONTINUED EXPANSION THROUGH DAYBREAK IN AREAS OVER AND JUST EAST OF THE HIGHER TERRAIN... SO EXPECT PARTLY TO MOSTLY CLOUDY SKIES FOR MOST AREAS ALONG AND NW OF I-85 IN THE NRN/NW CWA. THE LATEST RUNS OF THE HRRR MODEL SHOW LOWER STRATUS FORMING OVER NEARLY ALL OF CENTRAL NC DURING THE PREDAWN HOURS THIS MORNING... MIXING OUT BY MID MORNING. HAVE EVIDENCE OF THIS DEVELOPMENT AS YET... BUT BASED ON THE LACK OF WIND AND DEW POINTS STILL SITTING IN THE 50-55 DEGREE RANGE... THIS IS CERTAINLY POSSIBLE. AT ANY RATE... EXPECT AT LEAST PARTLY CLOUDY SKIES FOR MUCH OF THE CWA AROUND DAWN. ONCE THESE CLOUDS MIX OUT WITH HEATING... WE SHOULD SEE MOSTLY SUNNY SKIES TODAY WITH SCATTERED FLAT DIURNAL CUMULUS IN THE AFTERNOON. SURFACE HIGH PRESSURE CENTERED OVER SRN ONTARIO/LAKE HURON WILL WEAKEN TODAY BUT CONTINUE TO EXTEND SSE INTO CENTRAL/ERN NC... ANCHORED DIRECTLY BENEATH STATIONARY BUT WEAKENING MID LEVEL RIDGING. DESPITE THE CLOUDS THIS MORNING AND SCATTERED CLOUDS THIS AFTERNOON... VERY DRY/STABLE AIR ALOFT AND NEUTRAL OR SUBSIDING COLUMN WILL MAKE FOR A QUIET AND DRY DAY. LOW LEVEL THICKNESSES ARE EXPECTED TO START THE DAY IN THE 1360-1365 M RANGE (AROUND 20 M BELOW NORMAL)... RISING TO NEAR 1380 M... SUGGESTING HIGHS OF 75-80. FOR TONIGHT: THE VORTEX NOW SPINNING OVER ERN NE/KS WILL CROSS THE MID MISS VALLEY TONIGHT... BRINGING INCREASING (BUT STILL MODEST) MID-UPPER LEVEL DIVERGENT FLOW INTO THE WRN CAROLINAS... WHILE AT THE SURFACE... THE WEAKENING RIDGE STILL NOSES SOUTHWARD INTO THE AREA. THE OCCLUDING SURFACE FRONTAL SYSTEM WILL PUSH THROUGH THE LOWER MISS VALLEY INTO MS/AL LATE TONIGHT WHILE SECONDARY LOW PRESSURE BEGINS TO DEEPEN JUST OFF JAX... ALONG THE EAST-WEST FRONTAL ZONE. THE TIGHTENING MSLP GRADIENT SHOULD HOLD MOSTLY TO OUR SOUTH... LEAVING A PERSISTENT LIGHT/VARIABLE SURFACE FLOW OVER NC. WITH SURFACE DEW POINTS STEADILY RISING... EXPECT ANOTHER ROUND OF PATCHY STRATUS AND FOG DEVELOPMENT OVERNIGHT. THIS ALONG WITH THE INCREASING MID-HIGH CLOUDS SPREADING IN FROM THE WEST WILL RESULT IN A TREND TO PARTLY CLOUDY SKIES... WITH MOSTLY CLOUDY IN THE WRN CWA NEAR THE BETTER POOLING OF LOW LEVEL MOISTURE JUST EAST OF THE HIGHER TERRAIN. WILL STAY WITH A DRY FORECAST GIVEN THE STILL-LOW PW VALUES AND LACK OF FORCING FOR ASCENT. EXPECT LOWS FROM 49 NE TO 57 WEST... A BLEND OF STATISTICAL GUIDANCE. -GIH && .SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/... AS OF 310 AM TUESDAY... THE MID LEVEL VORTEX IS EXPECTED TO UNDERCUT THE ONTARIO-TO- MIDATLANTIC RIDGE ALOFT... MOVING FROM SRN IL ACROSS KY AND OVER VA/NC THROUGH WED NIGHT... BRINGING WEAK MID LEVEL DPVA AND WEAK UPPER DIVERGENCE OVER AREA. MEANWHILE... AT THE SURFACE... THE OCCLUDED FRONTAL SYSTEM OVER THE LOWER MISS VALLEY EXTENDING SOUTH OF LA WED MORNING WEAKENS AND FILLS AS IT SHIFTS SLOWLY EAST... WHILE THE LOW OFF JAX ALONG THE FRONT CONTINUES TO STRENGTHEN AS IT TOO DRIFTS EASTWARD. DURING ALL OF THIS... CENTRAL NC REMAINS INFLUENCED PRIMARILY BY THE LOW LEVEL RIDGE NOSING IN FROM THE NORTH... WITH A WEAK BUT STEADY FEED OF LOW LEVEL DRY AIR VIA THE NORTHEAST FLOW. THE RIDGE AXIS DOES ADJUST WITH THE SURFACE FLOW BACKING TO MORE NORTHERLY AS THE LOW DEEPENS OFF THE SOUTHEAST COAST... BUT FORECAST SOUNDINGS INDICATE CONTINUED FAIRLY DRY AIR THROUGHOUT THE LOWEST 8000 FT OF THE COLUMN. WE ARE LIKELY TO SEE OVERCAST MID LEVEL CLOUDINESS THROUGHOUT THE DAY AND NIGHT... AND THE DPVA ALONG WITH STEEPENING LAPSE RATES ABOVE THE 0C LEVEL MAY RESULT IN CONSIDERABLE VIRGA WED AFTERNOON THROUGH THE NIGHT. BUT APART FROM THE FAR WRN CWA WHERE UP-TERRAIN FLOW MAY ALLOW FOR ENOUGH LOWER LEVEL MOISTENING TO SUPPORT PATCHY LIGHT RAIN... IT LOOKS LIKE THE REMAINDER OF CENTRAL NC WILL HAVE TOO MUCH DRY AIR BELOW 8000 FT TO SUPPORT ANYTHING MORE THAN A FEW SPRINKLES. WILL NUDGE POPS DOWN AREAWIDE... WITH CHANCE POPS CONFINED TO THE FAR WEST AND SW CWA... TRENDING TO SLIGHT OR NO POPS FROM THE TRIANGLE NORTH AND EAST WITH LITTLE TO NO MEASURABLE RAIN EXPECTED. THE CLOUDS WILL LOWER THE DIURNAL TEMP RANGE... AND EXPECT HIGHS IN THE LOW-MID 70S (IN LINE WITH THICKNESSES ABOUT 10 M BELOW NORMAL) AND LOWS 54-60. -GIH && .LONG TERM /THURSDAY THROUGH MONDAY/... AS OF 315 AM TUESDAY... A SHORTWAVE TROUGH AXIS PASSING OVERHEAD EARLY THURSDAY WILL LEAD TO INCREASING SUBSIDENCE AND DRYING DURING THE DAY...WITH LINGERING LIGHT PRECIP MOVING TO THE COAST. LACK OF SIGNIFICANT PRECIP SHOULD LIMIT THE STRENGTHEN OF A COLD AIR DAMMING-LIKE AIRMASS NEAR THE SURFACE...SO THERE SHOULD BE CLEARING FROM THE NORTH THURSDAY AFTERNOON/EVENING...WITH THE BULK OF THE CLOUD COVER ATTRIBUTABLE TO THE UPPER TROUGH. TEMPS ARE A LITTLE TRICKY GIVEN THAT INITIAL CLOUD COVER IS SOMEWHAT DEPENDENT ON PRECIP WEDNESDAY/WEDNESDAY NIGHT AND A NORTHEASTERLY WIND WILL PREVAIL. HOWEVER...WITH CLEARING...GUIDANCE SUGGESTS MID/UPPER 70S ARE POSSIBLE WITH HEATING. WILL KEEP HIGHS A LITTLE BELOW GUIDANCE IN THE 73-77 RANGE. LOWS THURSDAY NIGHT IN THE LOW TO MID 50S. FRIDAY THROUGH MONDAY... MODELS ARE IN GOOD AGREEMENT REGARDING THE LONGWAVE PATTERN THIS WEEKEND...WITH A HIGHLY AMPLIFIED RIDGE WEST OF THE MOUNTAINS AND AN UPPER TROUGH/LOW OFF THE EAST COAST. BETWEEN THESE FEATURES...DEEP NORTH-NORTHEASTERLY FLOW WILL PREVAIL...WITH DEEPER MOISTURE TO STAY OFFSHORE. THE ECMWF HAS TRENDED STRONGER WITH AN UPPER LOW FORECAST TO DEVELOP WITHIN THE TROUGH FRIDAY AND DRIFT NORTH ALONG THE EAST COAST BY SUNDAY/MONDAY. THE ASSOCIATED SURFACE LOW WOULD BRING BETTER MOISTURE WESTWARD INTO THE COASTAL PLAIN MONDAY...WHILE A COLD FRONT OVER THE MIDWEST SLOWLY APPROACHES NC FROM THE WEST. HOWEVER...MODELS STILL KEEP NC DRY BETWEEN THESE FEATURES THROUGH MONDAY. PERSISTENT COLD ADVECTION ASSOCIATED WITH THE NORTHEASTERLY FLOW WILL 850MB TEMPS DOWN TO 7-8C...WITH LOW LEVEL THICKNESSES IN THE 1360-1365M RANGE EACH MORNING. THESE PARAMETERS SUGGEST TEMPS A CATEGORY BELOW NORMAL...WITH LOW TO MID 70S LIKELY SATURDAY AND SUNDAY. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... AS OF 710 AM TUESDAY... VFR THROUGH AT LEAST THIS EVENING. THE WIDESPREAD MORNING STRATUS AFFECTING RWI/RDU/GSO/INT ARE EXPECTED TO MIX OUT AND BECOME SCATTERED BY 15Z WITH THE ONSET OF HEATING. SCATTERED FLAT CUMULUS BASED AROUND 4000 FT AGL IS EXPECTED THIS AFTERNOON... AS THE MID/UPPER LEVELS STAY STABLE AND VERY DRY WHILE A THIN MOIST LAYER PERSISTS BENEATH THE SUBSIDENCE INVERSION ALOFT. THEN AFTER SUNSET... STABILIZING LOW LEVELS (LOWEST 4000 FT) AND VERY LIGHT WINDS WITH INCREASING NEAR-SURFACE MOISTURE WILL BRING A RISK OF MVFR FOG TONIGHT... ALTHOUGH THE BETTER CHANCE OF ADVERSE AVIATION CONDITIONS WILL HOLD OFF UNTIL AFTER 06Z TONIGHT. HIGH CLOUDS BASED ABOVE 15000 FT AGL WILL SPREAD IN FROM THE WEST TONIGHT. WINDS WILL BE VARIABLE IN DIRECTION THROUGH THE PERIOD AT SPEEDS UNDER 7 KTS. LOOKING BEYOND 12Z WEDNESDAY MORNING: PATCHY LOW STRATUS AND FOG ARE POSSIBLE THROUGH MID MORNING... PARTICULARLY NEAR BODIES OF WATER WHERE SHALLOW DENSE GROUND FOG MAY FORM PRIOR TO DAYBREAK. ANY SUCH CLOUDS SHOULD MIX OUT BEFORE 15Z WITH VFR CONDITIONS RETURNING... ALTHOUGH WE WILL SEE AN INCREASE IN STRATOCUMULUS BASED AROUND 3500 FT AGL ALONG WITH THICKENING AND LOWERING MID CLOUDS AS A STORM SYSTEM APPROACHES WEDNESDAY. IN GENERAL... VFR CONDITIONS WILL DOMINATE AS THIS SYSTEM CROSSES THE SOUTHEAST AND CAROLINAS... WITH CLOUD BASES MOSTLY ABOVE 3500 FT WITH LIGHT SHOWERS. THIS SYSTEM WILL EXIT ON THURSDAY WITH NEW HIGH PRESSURE RIDGING BUILDING IN AT THE SURFACE. SHALLOW FOG IS POSSIBLE EARLY FRIDAY MORNING WITH HIGH SURFACE RH AND LIGHT WINDS... BUT OTHERWISE EXPECT VFR CONDITIONS FRIDAY THROUGH SATURDAY BENEATH THE HIGH PRESSURE RIDGE. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...HARTFIELD SHORT TERM...HARTFIELD LONG TERM...22 AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
318 AM EDT TUE SEP 24 2013 .SYNOPSIS... A RIDGE OF HIGH PRESSURE SITTING OVER THE REGION WILL GRADUALLY WEAKEN TODAY AND TONIGHT. A LOW PRESSURE SYSTEM WILL CROSS THE SOUTHEAST STATES WEDNESDAY AND WEDNESDAY NIGHT... AS AN UPPER LEVEL TROUGH TRACKS ACROSS THE CAROLINAS. HIGH PRESSURE WILL BUILD BACK INTO THE REGION THURSDAY AND FRIDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 225 AM TUESDAY... FOR TODAY: RESIDUAL MOISTURE BENEATH THE SUBSIDENCE INVERSION ALOFT AND MOIST ISENTROPIC UPGLIDE AROUND 295K HAS RESULTED IN AREALLY EXPANDING STRATUS OVER CENTRAL/WRN VA AND WRN NC THIS MORNING... QUICKLY SPREADING INTO THE NRN AND WRN PORTIONS OF THE FORECAST AREA... WHICH WAS NOT DEPICTED WELL AT ALL BY THE NAM/GFS MODELS. TRENDS SUPPORT A CONTINUED EXPANSION THROUGH DAYBREAK IN AREAS OVER AND JUST EAST OF THE HIGHER TERRAIN... SO EXPECT PARTLY TO MOSTLY CLOUDY SKIES FOR MOST AREAS ALONG AND NW OF I-85 IN THE NRN/NW CWA. THE LATEST RUNS OF THE HRRR MODEL SHOW LOWER STRATUS FORMING OVER NEARLY ALL OF CENTRAL NC DURING THE PREDAWN HOURS THIS MORNING... MIXING OUT BY MID MORNING. HAVE EVIDENCE OF THIS DEVELOPMENT AS YET... BUT BASED ON THE LACK OF WIND AND DEW POINTS STILL SITTING IN THE 50-55 DEGREE RANGE... THIS IS CERTAINLY POSSIBLE. AT ANY RATE... EXPECT AT LEAST PARTLY CLOUDY SKIES FOR MUCH OF THE CWA AROUND DAWN. ONCE THESE CLOUDS MIX OUT WITH HEATING... WE SHOULD SEE MOSTLY SUNNY SKIES TODAY WITH SCATTERED FLAT DIURNAL CUMULUS IN THE AFTERNOON. SURFACE HIGH PRESSURE CENTERED OVER SRN ONTARIO/LAKE HURON WILL WEAKEN TODAY BUT CONTINUE TO EXTEND SSE INTO CENTRAL/ERN NC... ANCHORED DIRECTLY BENEATH STATIONARY BUT WEAKENING MID LEVEL RIDGING. DESPITE THE CLOUDS THIS MORNING AND SCATTERED CLOUDS THIS AFTERNOON... VERY DRY/STABLE AIR ALOFT AND NEUTRAL OR SUBSIDING COLUMN WILL MAKE FOR A QUIET AND DRY DAY. LOW LEVEL THICKNESSES ARE EXPECTED TO START THE DAY IN THE 1360-1365 M RANGE (AROUND 20 M BELOW NORMAL)... RISING TO NEAR 1380 M... SUGGESTING HIGHS OF 75-80. FOR TONIGHT: THE VORTEX NOW SPINNING OVER ERN NE/KS WILL CROSS THE MID MISS VALLEY TONIGHT... BRINGING INCREASING (BUT STILL MODEST) MID-UPPER LEVEL DIVERGENT FLOW INTO THE WRN CAROLINAS... WHILE AT THE SURFACE... THE WEAKENING RIDGE STILL NOSES SOUTHWARD INTO THE AREA. THE OCCLUDING SURFACE FRONTAL SYSTEM WILL PUSH THROUGH THE LOWER MISS VALLEY INTO MS/AL LATE TONIGHT WHILE SECONDARY LOW PRESSURE BEGINS TO DEEPEN JUST OFF JAX... ALONG THE EAST-WEST FRONTAL ZONE. THE TIGHTENING MSLP GRADIENT SHOULD HOLD MOSTLY TO OUR SOUTH... LEAVING A PERSISTENT LIGHT/VARIABLE SURFACE FLOW OVER NC. WITH SURFACE DEW POINTS STEADILY RISING... EXPECT ANOTHER ROUND OF PATCHY STRATUS AND FOG DEVELOPMENT OVERNIGHT. THIS ALONG WITH THE INCREASING MID-HIGH CLOUDS SPREADING IN FROM THE WEST WILL RESULT IN A TREND TO PARTLY CLOUDY SKIES... WITH MOSTLY CLOUDY IN THE WRN CWA NEAR THE BETTER POOLING OF LOW LEVEL MOISTURE JUST EAST OF THE HIGHER TERRAIN. WILL STAY WITH A DRY FORECAST GIVEN THE STILL-LOW PW VALUES AND LACK OF FORCING FOR ASCENT. EXPECT LOWS FROM 49 NE TO 57 WEST... A BLEND OF STATISTICAL GUIDANCE. -GIH && .SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/... AS OF 310 AM TUESDAY... THE MID LEVEL VORTEX IS EXPECTED TO UNDERCUT THE ONTARIO-TO- MIDATLANTIC RIDGE ALOFT... MOVING FROM SRN IL ACROSS KY AND OVER VA/NC THROUGH WED NIGHT... BRINGING WEAK MID LEVEL DPVA AND WEAK UPPER DIVERGENCE OVER AREA. MEANWHILE... AT THE SURFACE... THE OCCLUDED FRONTAL SYSTEM OVER THE LOWER MISS VALLEY EXTENDING SOUTH OF LA WED MORNING WEAKENS AND FILLS AS IT SHIFTS SLOWLY EAST... WHILE THE LOW OFF JAX ALONG THE FRONT CONTINUES TO STRENGTHEN AS IT TOO DRIFTS EASTWARD. DURING ALL OF THIS... CENTRAL NC REMAINS INFLUENCED PRIMARILY BY THE LOW LEVEL RIDGE NOSING IN FROM THE NORTH... WITH A WEAK BUT STEADY FEED OF LOW LEVEL DRY AIR VIA THE NORTHEAST FLOW. THE RIDGE AXIS DOES ADJUST WITH THE SURFACE FLOW BACKING TO MORE NORTHERLY AS THE LOW DEEPENS OFF THE SOUTHEAST COAST... BUT FORECAST SOUNDINGS INDICATE CONTINUED FAIRLY DRY AIR THROUGHOUT THE LOWEST 8000 FT OF THE COLUMN. WE ARE LIKELY TO SEE OVERCAST MID LEVEL CLOUDINESS THROUGHOUT THE DAY AND NIGHT... AND THE DPVA ALONG WITH STEEPENING LAPSE RATES ABOVE THE 0C LEVEL MAY RESULT IN CONSIDERABLE VIRGA WED AFTERNOON THROUGH THE NIGHT. BUT APART FROM THE FAR WRN CWA WHERE UP-TERRAIN FLOW MAY ALLOW FOR ENOUGH LOWER LEVEL MOISTENING TO SUPPORT PATCHY LIGHT RAIN... IT LOOKS LIKE THE REMAINDER OF CENTRAL NC WILL HAVE TOO MUCH DRY AIR BELOW 8000 FT TO SUPPORT ANYTHING MORE THAN A FEW SPRINKLES. WILL NUDGE POPS DOWN AREAWIDE... WITH CHANCE POPS CONFINED TO THE FAR WEST AND SW CWA... TRENDING TO SLIGHT OR NO POPS FROM THE TRIANGLE NORTH AND EAST WITH LITTLE TO NO MEASURABLE RAIN EXPECTED. THE CLOUDS WILL LOWER THE DIURNAL TEMP RANGE... AND EXPECT HIGHS IN THE LOW-MID 70S (IN LINE WITH THICKNESSES ABOUT 10 M BELOW NORMAL) AND LOWS 54-60. -GIH && .LONG TERM /THURSDAY THROUGH MONDAY/... AS OF 315 AM TUESDAY... A SHORTWAVE TROUGH AXIS PASSING OVERHEAD EARLY THURSDAY WILL LEAD TO INCREASING SUBSIDENCE AND DRYING DURING THE DAY...WITH LINGERING LIGHT PRECIP MOVING TO THE COAST. LACK OF SIGNIFICANT PRECIP SHOULD LIMIT THE STRENGTHEN OF A COLD AIR DAMMING-LIKE AIRMASS NEAR THE SURFACE...SO THERE SHOULD BE CLEARING FROM THE NORTH THURSDAY AFTERNOON/EVENING...WITH THE BULK OF THE CLOUD COVER ATTRIBUTABLE TO THE UPPER TROUGH. TEMPS ARE A LITTLE TRICKY GIVEN THAT INITIAL CLOUD COVER IS SOMEWHAT DEPENDENT ON PRECIP WEDNESDAY/WEDNESDAY NIGHT AND A NORTHEASTERLY WIND WILL PREVAIL. HOWEVER...WITH CLEARING...GUIDANCE SUGGESTS MID/UPPER 70S ARE POSSIBLE WITH HEATING. WILL KEEP HIGHS A LITTLE BELOW GUIDANCE IN THE 73-77 RANGE. LOWS THURSDAY NIGHT IN THE LOW TO MID 50S. FRIDAY THROUGH MONDAY... MODELS ARE IN GOOD AGREEMENT REGARDING THE LONGWAVE PATTERN THIS WEEKEND...WITH A HIGHLY AMPLIFIED RIDGE WEST OF THE MOUNTAINS AND AN UPPER TROUGH/LOW OFF THE EAST COAST. BETWEEN THESE FEATURES...DEEP NORTH-NORTHEASTERLY FLOW WILL PREVAIL...WITH DEEPER MOISTURE TO STAY OFFSHORE. THE ECMWF HAS TRENDED STRONGER WITH AN UPPER LOW FORECAST TO DEVELOP WITHIN THE TROUGH FRIDAY AND DRIFT NORTH ALONG THE EAST COAST BY SUNDAY/MONDAY. THE ASSOCIATED SURFACE LOW WOULD BRING BETTER MOISTURE WESTWARD INTO THE COASTAL PLAIN MONDAY...WHILE A COLD FRONT OVER THE MIDWEST SLOWLY APPROACHES NC FROM THE WEST. HOWEVER...MODELS STILL KEEP NC DRY BETWEEN THESE FEATURES THROUGH MONDAY. PERSISTENT COLD ADVECTION ASSOCIATED WITH THE NORTHEASTERLY FLOW WILL 850MB TEMPS DOWN TO 7-8C...WITH LOW LEVEL THICKNESSES IN THE 1360-1365M RANGE EACH MORNING. THESE PARAMETERS SUGGEST TEMPS A CATEGORY BELOW NORMAL...WITH LOW TO MID 70S LIKELY SATURDAY AND SUNDAY. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... AS OF 1250 AM TUESDAY... REST OF TONIGHT: VFR STRATUS CONTINUES TO EXPAND IN AREA OVER CENTRAL VA INTO WRN NC... AND BASED ON THIS TREND APPEARS POISED TO SPREAD INTO INT/GSO AND PERHAPS RDU AS WELL OVERNIGHT. PATCHY VFR CLOUDS AFFECTED FAY EARLIER AND ADDITIONAL CLOUDS REMAIN POSSIBLE THROUGH DAYBREAK. MEANWHILE... BANKS OF SHALLOW DENSE FOG HAVE FORMED NEAR RWI -- PROMPTED BY THE NEARBY RIVER -- AND THIS FOG SHOULD PERSIST OVERNIGHT... WITH VSBYS MOSTLY IFR BUT VARYING BETWEEN LIFR AND MVFR THROUGH DAYBREAK. HRRR MODEL DEPICTS LOW IFR STRATUS SPREADING ACROSS ALL OF CENTRAL NC OVERNIGHT... AND WHILE THIS LOOKS OVERDONE... WE WILL KEEP A CLOSE EYE ON CLOUD TRENDS THROUGH THE REST OF THE NIGHT. AFTER 12Z: VFR THROUGH AT LEAST THIS EVENING. ANY MORNING STRATUS WILL MIX OUT BY 14Z WITH THE ONSET OF HEATING... THEN ANOTHER ROUND OF MOSTLY SCATTERED FLAT CUMULUS BASED AROUND 4000 FT AGL IS EXPECTED THIS AFTERNOON... AS THE MID/UPPER LEVELS STAY STABLE AND VERY DRY WHILE A THIN MOIST LAYER PERSISTS BENEATH THE SUBSIDENCE INVERSION ALOFT. THEN AFTER SUNSET... STABILIZING LOW LEVELS (LOWEST 4000 FT) AND VERY LIGHT WINDS WITH INCREASING NEAR-SURFACE MOISTURE WILL BRING A RISK OF MVFR FOG TONIGHT... ALTHOUGH THE BETTER CHANCE OF ADVERSE AVIATION CONDITIONS WILL HOLD OFF UNTIL AFTER 06Z TONIGHT. HIGH CLOUDS BASED ABOVE 15000 FT AGL WILL SPREAD IN FROM THE WEST TONIGHT. WINDS WILL BE VARIABLE IN DIRECTION THROUGH THE PERIOD AT SPEEDS UNDER 7 KTS. LOOKING BEYOND 06Z EARLY WEDNESDAY MORNING: PATCHY LOW STRATUS AND FOG ARE POSSIBLE THROUGH MID MORNING... PARTICULARLY NEAR BODIES OF WATER WHERE SHALLOW DENSE GROUND FOG MAY FORM PRIOR TO DAYBREAK. ANY SUCH CLOUDS SHOULD MIX OUT BEFORE 15Z WITH VFR CONDITIONS RETURNING... ALTHOUGH WE WILL SEE AN INCREASE IN STRATOCUMULUS BASED AROUND 3500 FT AGL ALONG WITH THICKENING AND LOWERING MID CLOUDS AS A STORM SYSTEM APPROACHES WEDNESDAY. IN GENERAL... VFR CONDITIONS WILL DOMINATE AS THIS SYSTEM CROSSES THE SOUTHEAST AND CAROLINAS... WITH CLOUD BASES MOSTLY ABOVE 3500 FT WITH LIGHT SHOWERS. THIS SYSTEM WILL EXIT ON THURSDAY WITH NEW HIGH PRESSURE RIDGING BUILDING IN AT THE SURFACE. SHALLOW FOG IS POSSIBLE EARLY FRIDAY MORNING WITH HIGH SURFACE RH AND LIGHT WINDS... BUT OTHERWISE EXPECT VFR CONDITIONS FRIDAY THROUGH SATURDAY BENEATH THE HIGH PRESSURE RIDGE. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...HARTFIELD SHORT TERM...HARTFIELD LONG TERM...22 AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
315 AM EDT TUE SEP 24 2013 .SYNOPSIS... A RIDGE OF HIGH PRESSURE SITTING OVER THE REGION WILL GRADUALLY WEAKEN TODAY AND TONIGHT. A LOW PRESSURE SYSTEM WILL CROSS THE SOUTHEAST STATES WEDNESDAY AND WEDNESDAY NIGHT... AS AN UPPER LEVEL TROUGH TRACKS ACROSS THE CAROLINAS. HIGH PRESSURE WILL BUILD BACK INTO THE REGION THURSDAY AND FRIDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 225 AM TUESDAY... FOR TODAY: RESIDUAL MOISTURE BENEATH THE SUBSIDENCE INVERSION ALOFT AND MOIST ISENTROPIC UPGLIDE AROUND 295K HAS RESULTED IN AREALLY EXPANDING STRATUS OVER CENTRAL/WRN VA AND WRN NC THIS MORNING... QUICKLY SPREADING INTO THE NRN AND WRN PORTIONS OF THE FORECAST AREA... WHICH WAS NOT DEPICTED WELL AT ALL BY THE NAM/GFS MODELS. TRENDS SUPPORT A CONTINUED EXPANSION THROUGH DAYBREAK IN AREAS OVER AND JUST EAST OF THE HIGHER TERRAIN... SO EXPECT PARTLY TO MOSTLY CLOUDY SKIES FOR MOST AREAS ALONG AND NW OF I-85 IN THE NRN/NW CWA. THE LATEST RUNS OF THE HRRR MODEL SHOW LOWER STRATUS FORMING OVER NEARLY ALL OF CENTRAL NC DURING THE PREDAWN HOURS THIS MORNING... MIXING OUT BY MID MORNING. HAVE EVIDENCE OF THIS DEVELOPMENT AS YET... BUT BASED ON THE LACK OF WIND AND DEW POINTS STILL SITTING IN THE 50-55 DEGREE RANGE... THIS IS CERTAINLY POSSIBLE. AT ANY RATE... EXPECT AT LEAST PARTLY CLOUDY SKIES FOR MUCH OF THE CWA AROUND DAWN. ONCE THESE CLOUDS MIX OUT WITH HEATING... WE SHOULD SEE MOSTLY SUNNY SKIES TODAY WITH SCATTERED FLAT DIURNAL CUMULUS IN THE AFTERNOON. SURFACE HIGH PRESSURE CENTERED OVER SRN ONTARIO/LAKE HURON WILL WEAKEN TODAY BUT CONTINUE TO EXTEND SSE INTO CENTRAL/ERN NC... ANCHORED DIRECTLY BENEATH STATIONARY BUT WEAKENING MID LEVEL RIDGING. DESPITE THE CLOUDS THIS MORNING AND SCATTERED CLOUDS THIS AFTERNOON... VERY DRY/STABLE AIR ALOFT AND NEUTRAL OR SUBSIDING COLUMN WILL MAKE FOR A QUIET AND DRY DAY. LOW LEVEL THICKNESSES ARE EXPECTED TO START THE DAY IN THE 1360-1365 M RANGE (AROUND 20 M BELOW NORMAL)... RISING TO NEAR 1380 M... SUGGESTING HIGHS OF 75-80. FOR TONIGHT: THE VORTEX NOW SPINNING OVER ERN NE/KS WILL CROSS THE MID MISS VALLEY TONIGHT... BRINGING INCREASING (BUT STILL MODEST) MID-UPPER LEVEL DIVERGENT FLOW INTO THE WRN CAROLINAS... WHILE AT THE SURFACE... THE WEAKENING RIDGE STILL NOSES SOUTHWARD INTO THE AREA. THE OCCLUDING SURFACE FRONTAL SYSTEM WILL PUSH THROUGH THE LOWER MISS VALLEY INTO MS/AL LATE TONIGHT WHILE SECONDARY LOW PRESSURE BEGINS TO DEEPEN JUST OFF JAX... ALONG THE EAST-WEST FRONTAL ZONE. THE TIGHTENING MSLP GRADIENT SHOULD HOLD MOSTLY TO OUR SOUTH... LEAVING A PERSISTENT LIGHT/VARIABLE SURFACE FLOW OVER NC. WITH SURFACE DEW POINTS STEADILY RISING... EXPECT ANOTHER ROUND OF PATCHY STRATUS AND FOG DEVELOPMENT OVERNIGHT. THIS ALONG WITH THE INCREASING MID-HIGH CLOUDS SPREADING IN FROM THE WEST WILL RESULT IN A TREND TO PARTLY CLOUDY SKIES... WITH MOSTLY CLOUDY IN THE WRN CWA NEAR THE BETTER POOLING OF LOW LEVEL MOISTURE JUST EAST OF THE HIGHER TERRAIN. WILL STAY WITH A DRY FORECAST GIVEN THE STILL-LOW PW VALUES AND LACK OF FORCING FOR ASCENT. EXPECT LOWS FROM 49 NE TO 57 WEST... A BLEND OF STATISTICAL GUIDANCE. -GIH && .SHORT TERM / /... AS OF 325 PM MONDAY... TO BE UPDATED SHORTLY. && .LONG TERM /THURSDAY THROUGH MONDAY/... AS OF 315 AM TUESDAY... A SHORTWAVE TROUGH AXIS PASSING OVERHEAD EARLY THURSDAY WILL LEAD TO INCREASING SUBSIDENCE AND DRYING DURING THE DAY...WITH LINGERING LIGHT PRECIP MOVING TO THE COAST. LACK OF SIGNIFICANT PRECIP SHOULD LIMIT THE STRENGTHEN OF A COLD AIR DAMMING-LIKE AIRMASS NEAR THE SURFACE...SO THERE SHOULD BE CLEARING FROM THE NORTH THURSDAY AFTERNOON/EVENING...WITH THE BULK OF THE CLOUD COVER ATTRIBUTABLE TO THE UPPER TROUGH. TEMPS ARE A LITTLE TRICKY GIVEN THAT INITIAL CLOUD COVER IS SOMEWHAT DEPENDENT ON PRECIP WEDNESDAY/WEDNESDAY NIGHT AND A NORTHEASTERLY WIND WILL PREVAIL. HOWEVER...WITH CLEARING...GUIDANCE SUGGESTS MID/UPPER 70S ARE POSSIBLE WITH HEATING. WILL KEEP HIGHS A LITTLE BELOW GUIDANCE IN THE 73-77 RANGE. LOWS THURSDAY NIGHT IN THE LOW TO MID 50S. FRIDAY THROUGH MONDAY... MODELS ARE IN GOOD AGREEMENT REGARDING THE LONGWAVE PATTERN THIS WEEKEND...WITH A HIGHLY AMPLIFIED RIDGE WEST OF THE MOUNTAINS AND AN UPPER TROUGH/LOW OFF THE EAST COAST. BETWEEN THESE FEATURES...DEEP NORTH-NORTHEASTERLY FLOW WILL PREVAIL...WITH DEEPER MOISTURE TO STAY OFFSHORE. THE ECMWF HAS TRENDED STRONGER WITH AN UPPER LOW FORECAST TO DEVELOP WITHIN THE TROUGH FRIDAY AND DRIFT NORTH ALONG THE EAST COAST BY SUNDAY/MONDAY. THE ASSOCIATED SURFACE LOW WOULD BRING BETTER MOISTURE WESTWARD INTO THE COASTAL PLAIN MONDAY...WHILE A COLD FRONT OVER THE MIDWEST SLOWLY APPROACHES NC FROM THE WEST. HOWEVER...MODELS STILL KEEP NC DRY BETWEEN THESE FEATURES THROUGH MONDAY. PERSISTENT COLD ADVECTION ASSOCIATED WITH THE NORTHEASTERLY FLOW WILL 850MB TEMPS DOWN TO 7-8C...WITH LOW LEVEL THICKNESSES IN THE 1360-1365M RANGE EACH MORNING. THESE PARAMETERS SUGGEST TEMPS A CATEGORY BELOW NORMAL...WITH LOW TO MID 70S LIKELY SATURDAY AND SUNDAY. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... AS OF 1250 AM TUESDAY... REST OF TONIGHT: VFR STRATUS CONTINUES TO EXPAND IN AREA OVER CENTRAL VA INTO WRN NC... AND BASED ON THIS TREND APPEARS POISED TO SPREAD INTO INT/GSO AND PERHAPS RDU AS WELL OVERNIGHT. PATCHY VFR CLOUDS AFFECTED FAY EARLIER AND ADDITIONAL CLOUDS REMAIN POSSIBLE THROUGH DAYBREAK. MEANWHILE... BANKS OF SHALLOW DENSE FOG HAVE FORMED NEAR RWI -- PROMPTED BY THE NEARBY RIVER -- AND THIS FOG SHOULD PERSIST OVERNIGHT... WITH VSBYS MOSTLY IFR BUT VARYING BETWEEN LIFR AND MVFR THROUGH DAYBREAK. HRRR MODEL DEPICTS LOW IFR STRATUS SPREADING ACROSS ALL OF CENTRAL NC OVERNIGHT... AND WHILE THIS LOOKS OVERDONE... WE WILL KEEP A CLOSE EYE ON CLOUD TRENDS THROUGH THE REST OF THE NIGHT. AFTER 12Z: VFR THROUGH AT LEAST THIS EVENING. ANY MORNING STRATUS WILL MIX OUT BY 14Z WITH THE ONSET OF HEATING... THEN ANOTHER ROUND OF MOSTLY SCATTERED FLAT CUMULUS BASED AROUND 4000 FT AGL IS EXPECTED THIS AFTERNOON... AS THE MID/UPPER LEVELS STAY STABLE AND VERY DRY WHILE A THIN MOIST LAYER PERSISTS BENEATH THE SUBSIDENCE INVERSION ALOFT. THEN AFTER SUNSET... STABILIZING LOW LEVELS (LOWEST 4000 FT) AND VERY LIGHT WINDS WITH INCREASING NEAR-SURFACE MOISTURE WILL BRING A RISK OF MVFR FOG TONIGHT... ALTHOUGH THE BETTER CHANCE OF ADVERSE AVIATION CONDITIONS WILL HOLD OFF UNTIL AFTER 06Z TONIGHT. HIGH CLOUDS BASED ABOVE 15000 FT AGL WILL SPREAD IN FROM THE WEST TONIGHT. WINDS WILL BE VARIABLE IN DIRECTION THROUGH THE PERIOD AT SPEEDS UNDER 7 KTS. LOOKING BEYOND 06Z EARLY WEDNESDAY MORNING: PATCHY LOW STRATUS AND FOG ARE POSSIBLE THROUGH MID MORNING... PARTICULARLY NEAR BODIES OF WATER WHERE SHALLOW DENSE GROUND FOG MAY FORM PRIOR TO DAYBREAK. ANY SUCH CLOUDS SHOULD MIX OUT BEFORE 15Z WITH VFR CONDITIONS RETURNING... ALTHOUGH WE WILL SEE AN INCREASE IN STRATOCUMULUS BASED AROUND 3500 FT AGL ALONG WITH THICKENING AND LOWERING MID CLOUDS AS A STORM SYSTEM APPROACHES WEDNESDAY. IN GENERAL... VFR CONDITIONS WILL DOMINATE AS THIS SYSTEM CROSSES THE SOUTHEAST AND CAROLINAS... WITH CLOUD BASES MOSTLY ABOVE 3500 FT WITH LIGHT SHOWERS. THIS SYSTEM WILL EXIT ON THURSDAY WITH NEW HIGH PRESSURE RIDGING BUILDING IN AT THE SURFACE. SHALLOW FOG IS POSSIBLE EARLY FRIDAY MORNING WITH HIGH SURFACE RH AND LIGHT WINDS... BUT OTHERWISE EXPECT VFR CONDITIONS FRIDAY THROUGH SATURDAY BENEATH THE HIGH PRESSURE RIDGE. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...HARTFIELD SHORT TERM... LONG TERM...22 AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
228 AM EDT TUE SEP 24 2013 .SYNOPSIS... A RIDGE OF HIGH PRESSURE SITTING OVER THE REGION WILL GRADUALLY WEAKEN TODAY AND TONIGHT. A LOW PRESSURE SYSTEM WILL CROSS THE SOUTHEAST STATES WEDNESDAY AND WEDNESDAY NIGHT... AS AN UPPER LEVEL TROUGH TRACKS ACROSS THE CAROLINAS. HIGH PRESSURE WILL BUILD BACK INTO THE REGION THURSDAY AND FRIDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 225 AM TUESDAY... FOR TODAY: RESIDUAL MOISTURE BENEATH THE SUBSIDENCE INVERSION ALOFT AND MOIST ISENTROPIC UPGLIDE AROUND 295K HAS RESULTED IN AREALLY EXPANDING STRATUS OVER CENTRAL/WRN VA AND WRN NC THIS MORNING... QUICKLY SPREADING INTO THE NRN AND WRN PORTIONS OF THE FORECAST AREA... WHICH WAS NOT DEPICTED WELL AT ALL BY THE NAM/GFS MODELS. TRENDS SUPPORT A CONTINUED EXPANSION THROUGH DAYBREAK IN AREAS OVER AND JUST EAST OF THE HIGHER TERRAIN... SO EXPECT PARTLY TO MOSTLY CLOUDY SKIES FOR MOST AREAS ALONG AND NW OF I-85 IN THE NRN/NW CWA. THE LATEST RUNS OF THE HRRR MODEL SHOW LOWER STRATUS FORMING OVER NEARLY ALL OF CENTRAL NC DURING THE PREDAWN HOURS THIS MORNING... MIXING OUT BY MID MORNING. HAVE EVIDENCE OF THIS DEVELOPMENT AS YET... BUT BASED ON THE LACK OF WIND AND DEW POINTS STILL SITTING IN THE 50-55 DEGREE RANGE... THIS IS CERTAINLY POSSIBLE. AT ANY RATE... EXPECT AT LEAST PARTLY CLOUDY SKIES FOR MUCH OF THE CWA AROUND DAWN. ONCE THESE CLOUDS MIX OUT WITH HEATING... WE SHOULD SEE MOSTLY SUNNY SKIES TODAY WITH SCATTERED FLAT DIURNAL CUMULUS IN THE AFTERNOON. SURFACE HIGH PRESSURE CENTERED OVER SRN ONTARIO/LAKE HURON WILL WEAKEN TODAY BUT CONTINUE TO EXTEND SSE INTO CENTRAL/ERN NC... ANCHORED DIRECTLY BENEATH STATIONARY BUT WEAKENING MID LEVEL RIDGING. DESPITE THE CLOUDS THIS MORNING AND SCATTERED CLOUDS THIS AFTERNOON... VERY DRY/STABLE AIR ALOFT AND NEUTRAL OR SUBSIDING COLUMN WILL MAKE FOR A QUIET AND DRY DAY. LOW LEVEL THICKNESSES ARE EXPECTED TO START THE DAY IN THE 1360-1365 M RANGE (AROUND 20 M BELOW NORMAL)... RISING TO NEAR 1380 M... SUGGESTING HIGHS OF 75-80. FOR TONIGHT: THE VORTEX NOW SPINNING OVER ERN NE/KS WILL CROSS THE MID MISS VALLEY TONIGHT... BRINGING INCREASING (BUT STILL MODEST) MID-UPPER LEVEL DIVERGENT FLOW INTO THE WRN CAROLINAS... WHILE AT THE SURFACE... THE WEAKENING RIDGE STILL NOSES SOUTHWARD INTO THE AREA. THE OCCLUDING SURFACE FRONTAL SYSTEM WILL PUSH THROUGH THE LOWER MISS VALLEY INTO MS/AL LATE TONIGHT WHILE SECONDARY LOW PRESSURE BEGINS TO DEEPEN JUST OFF JAX... ALONG THE EAST-WEST FRONTAL ZONE. THE TIGHTENING MSLP GRADIENT SHOULD HOLD MOSTLY TO OUR SOUTH... LEAVING A PERSISTENT LIGHT/VARIABLE SURFACE FLOW OVER NC. WITH SURFACE DEW POINTS STEADILY RISING... EXPECT ANOTHER ROUND OF PATCHY STRATUS AND FOG DEVELOPMENT OVERNIGHT. THIS ALONG WITH THE INCREASING MID-HIGH CLOUDS SPREADING IN FROM THE WEST WILL RESULT IN A TREND TO PARTLY CLOUDY SKIES... WITH MOSTLY CLOUDY IN THE WRN CWA NEAR THE BETTER POOLING OF LOW LEVEL MOISTURE JUST EAST OF THE HIGHER TERRAIN. WILL STAY WITH A DRY FORECAST GIVEN THE STILL-LOW PW VALUES AND LACK OF FORCING FOR ASCENT. EXPECT LOWS FROM 49 NE TO 57 WEST... A BLEND OF STATISTICAL GUIDANCE. -GIH && .SHORT TERM / /... AS OF 325 PM MONDAY... TO BE UPDATED SHORTLY. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... AS OF 245 PM MONDAY... CONFIDENCE IN AN UNSETTLED PATTERN FOR WEDNESDAY INTO A PORTION OF THURSDAY HAS INCREASED A BIT TODAY. MOST MODELS ARE INDICATING A MID/UPPER TROUGH AMPLIFICATION OVER THE EASTERN STATES... SHIFTING OFFSHORE LATE WEEK. THE IMPORTANT SURFACE WAVE IS STILL SUPPORTED TO DEVELOP/TRACK WELL TO OUR SOUTH AND EAST... FROM THE GULF COAST 12Z WEDNESDAY... EAST ACROSS NORTHERN FLORIDA EARLY THURSDAY... THEN OFF THE SOUTH ATLANTIC COAST FRIDAY. THE EC CONTINUES TO BE THE FAVORED MODEL OF CHOICE CONCERNING OPERATIONAL RUNS DUE TO ITS CONSISTENCY WITH THE EVOLUTION OF THE SYSTEM IN RECENT DAYS THROUGH TODAY. MOST OF THE HEAVY RAIN WITH THIS SYSTEM SHOULD BE CONFINED TO THE DEEP SOUTH AND POSSIBLY INTO SC AS THE MAIN LOW LEVEL BOUNDARY WILL BE HUNG UP THERE. HOWEVER... THERE IS STILL A GOOD CHANCE OF RAIN WITH THE MID/UPPER SUPPORT ALONG WITH ISENTROPIC LIFT WED-WED NIGHT. AFTER THE LOW MOVES OFFSHORE... ANOTHER MID/UPPER LOW MAY AGAIN TARGET THE GREAT LAKES AND MIDWEST SUPPORTED BY TELECONNECTIONS WITH THE NE PAC UPPER TROUGH... AND DOWNSTREAM UPPER RIDGE DEVELOPMENT OVER THE ROCKIES. THIS MAY LEAD TO MORE IN THE WAY OF UNSETTLED CONDITIONS LATER SUNDAY INTO EARLY NEXT WEEK. SENSIBLE WEATHER FOR CENTRAL NC SHOULD CONSIST OF THE HIGHEST CHANCES OF RAIN ON WEDNESDAY INTO WEDNESDAY NIGHT... ASSOCIATED WITH THE MID/UPPER TROUGH. THEN THE HIGHEST POP IN THE EAST ON THURSDAY (MAINLY MORNING) WITH THE SURFACE WAVE TRACKING TO OUR SOUTH AND EAST AND OFFSHORE THEN. IT IS STILL TOO EARLY TO FORECAST A FULL BLOWN COLD AIR DAMMING EVENT THAT WOULD BE OF IN-SITU OR POSSIBLY HYBRID NATURE WED INTO THU... GIVEN THE LACK OF A SUPPORTING PARENT SURFACE HIGH THAT WOULD BE STRONG ENOUGH... AND IN THE PREFERRED LOCATION FOR ANYTHING MORE IN OUR REGION. THE DEVELOPMENT OF AN IN-SITU OR WEAK HYBRID CAD EVENT SHOULD BE HIGHLY DEPENDENT BY THE QPF ON WED... WHICH IS STILL VERY MUCH IN QUESTION... AND IS STILL EXPECTED TO BE LESS THAN 0.25 OF AN INCH IN THE DAMMING REGION. DUE TO THE LACK OF CONFIDENCE ON ANYTHING MORE THAN 0.25 OF AN INCH OF RAIN WED-WED NIGHT AT THE CURRENT TIME... WE WILL MAINTAIN POP IN THE CHANCE TO HIGH CHANCE CATEGORY... QPF OF LESS THAN 0.25 OF AN INCH... AND TEMPERATURES (WHILE COOLER THAN NORMAL)... NOT BY MUCH (2-5 DEGREES OR SO FOR DAYTIME HIGHS). GIVEN THE EXPECTATION OF A WEAK CAD AT BEST... SKIES SHOULD CLEAR MORE QUICKLY LATE THU AND FRI AS THE STORM SHIFTS WELL OFFSHORE. LOWS WILL COOL INTO THE LOWER TO MID 50S FRI... WITH HIGHS IN THE MID 70S WITH MOSTLY SUNNY SKIES FRI. SAT-SUN... SKIES SHOULD CONTINUE MOSTLY CLEAR/MOSTLY SUNNY AS HIGH PRESSURE IS EXPECTED TO EXTEND DOWN THE EASTERN SEABOARD INTO SUNDAY. LOWS IN THE LOWER TO MID 50S AND HIGHS IN THE LOWER TO MID 70S ARE EXPECTED. SUNDAY NIGHT AND MONDAY... EXPECT SOME INCREASE IN CLOUDINESS FOR NOW... POSSIBLY A CHANCE OF RAIN AGAIN - BUT UNCERTAINTY THIS FAR OUT SUPPORTS A SLIGHT CHANCE OF SHOWERS IN THE FORECAST MONDAY. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... AS OF 1250 AM TUESDAY... REST OF TONIGHT: VFR STRATUS CONTINUES TO EXPAND IN AREA OVER CENTRAL VA INTO WRN NC... AND BASED ON THIS TREND APPEARS POISED TO SPREAD INTO INT/GSO AND PERHAPS RDU AS WELL OVERNIGHT. PATCHY VFR CLOUDS AFFECTED FAY EARLIER AND ADDITIONAL CLOUDS REMAIN POSSIBLE THROUGH DAYBREAK. MEANWHILE... BANKS OF SHALLOW DENSE FOG HAVE FORMED NEAR RWI -- PROMPTED BY THE NEARBY RIVER -- AND THIS FOG SHOULD PERSIST OVERNIGHT... WITH VSBYS MOSTLY IFR BUT VARYING BETWEEN LIFR AND MVFR THROUGH DAYBREAK. HRRR MODEL DEPICTS LOW IFR STRATUS SPREADING ACROSS ALL OF CENTRAL NC OVERNIGHT... AND WHILE THIS LOOKS OVERDONE... WE WILL KEEP A CLOSE EYE ON CLOUD TRENDS THROUGH THE REST OF THE NIGHT. AFTER 12Z: VFR THROUGH AT LEAST THIS EVENING. ANY MORNING STRATUS WILL MIX OUT BY 14Z WITH THE ONSET OF HEATING... THEN ANOTHER ROUND OF MOSTLY SCATTERED FLAT CUMULUS BASED AROUND 4000 FT AGL IS EXPECTED THIS AFTERNOON... AS THE MID/UPPER LEVELS STAY STABLE AND VERY DRY WHILE A THIN MOIST LAYER PERSISTS BENEATH THE SUBSIDENCE INVERSION ALOFT. THEN AFTER SUNSET... STABILIZING LOW LEVELS (LOWEST 4000 FT) AND VERY LIGHT WINDS WITH INCREASING NEAR-SURFACE MOISTURE WILL BRING A RISK OF MVFR FOG TONIGHT... ALTHOUGH THE BETTER CHANCE OF ADVERSE AVIATION CONDITIONS WILL HOLD OFF UNTIL AFTER 06Z TONIGHT. HIGH CLOUDS BASED ABOVE 15000 FT AGL WILL SPREAD IN FROM THE WEST TONIGHT. WINDS WILL BE VARIABLE IN DIRECTION THROUGH THE PERIOD AT SPEEDS UNDER 7 KTS. LOOKING BEYOND 06Z EARLY WEDNESDAY MORNING: PATCHY LOW STRATUS AND FOG ARE POSSIBLE THROUGH MID MORNING... PARTICULARLY NEAR BODIES OF WATER WHERE SHALLOW DENSE GROUND FOG MAY FORM PRIOR TO DAYBREAK. ANY SUCH CLOUDS SHOULD MIX OUT BEFORE 15Z WITH VFR CONDITIONS RETURNING... ALTHOUGH WE WILL SEE AN INCREASE IN STRATOCUMULUS BASED AROUND 3500 FT AGL ALONG WITH THICKENING AND LOWERING MID CLOUDS AS A STORM SYSTEM APPROACHES WEDNESDAY. IN GENERAL... VFR CONDITIONS WILL DOMINATE AS THIS SYSTEM CROSSES THE SOUTHEAST AND CAROLINAS... WITH CLOUD BASES MOSTLY ABOVE 3500 FT WITH LIGHT SHOWERS. THIS SYSTEM WILL EXIT ON THURSDAY WITH NEW HIGH PRESSURE RIDGING BUILDING IN AT THE SURFACE. SHALLOW FOG IS POSSIBLE EARLY FRIDAY MORNING WITH HIGH SURFACE RH AND LIGHT WINDS... BUT OTHERWISE EXPECT VFR CONDITIONS FRIDAY THROUGH SATURDAY BENEATH THE HIGH PRESSURE RIDGE. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...HARTFIELD SHORT TERM... LONG TERM...BADGETT AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1252 AM EDT TUE SEP 24 2013 .SYNOPSIS... A RIDGE OF HIGH PRESSURE SITTING OVER THE REGION WILL GRADUALLY WEAKEN TODAY AND TONIGHT. A LOW PRESSURE SYSTEM WILL CROSS THE SOUTHEAST STATES WEDNESDAY AND WEDNESDAY NIGHT... AS AN UPPER LEVEL TROUGH TRACKS ACROSS THE CAROLINAS. HIGH PRESSURE WILL BUILD BACK INTO THE REGION THURSDAY AND FRIDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 930 PM MONDAY... LAYER OF STRATOCU THAT WAS FAIRLY PREVALENT ACROSS CENTRAL NC THIS AFTERNOON DISSIPATED WITH THE LOSS OF HEATING. AN AREA OF HIGH PRESSURE AT THE SURFACE AND ALOFT WILL PERSIST ACROSS THE FORECAST AREA OVERNIGHT INTO TUESDAY MORNING. THIS WEATHER PATTERN USUALLY SIGNALS A SEASONABLY COOL AND DRY FORECAST. THIS SEEMS PLAUSIBLE AS SFC DEWPOINTS THIS AFTERNOON WERE IN THE UPPER 40S TO LOWER 50S. EXPECT COMPARABLE MIN TEMPS TONIGHT WITH MID 40S POSSIBLE IN THE NORMALLY COLDER LOCATIONS (SUCH AS NEW HILL...LOUISBURG... HENDERSON...ETC.) EXCEPTION TO THIS MAY BE THE FAR WESTERN PIEDMONT WHERE MODEL GUIDANCE CONTINUES TO SUGGEST A SHALLOW LAYER OF MOISTURE CENTERED JUST BELOW 850MB. 00Z GSO SOUNDING DEPICTS 2 DEG C DEWPOINT SPREAD AT THAT LEVEL. THIS MOIST LAYER COUPLED WITH LIFT GENERATED BY WEAK LOW LEVEL WAA WHICH MAY RESULT IN A LAYER OF STRATUS OVERNIGHT. IF CLOUDS DO DEVELOP...THIS WILL ACT AS A BLANKET AND REDUCE THE HEAT LOSS AT THE SURFACE RESULTING IN WARMER TEMPS. INHERITED A FORECAST OF MID 50S ALONG YADKIN RIVER VALLEY/NW PIEDMONT. DUE TO LACK OF CLOUDS EARLY THIS EVENING AND WINDS NEAR CALM...POTENTIAL FOR TEMPS TO COOL A BIT LOWER. ADJUSTED MIN TEMPS TO THE LOWER 50S IN THE TRIAD REGION. && .SHORT TERM /TUESDAY AND TUESDAY NIGHT/... AS OF 325 PM MONDAY... THE SHORTWAVE RIDGE PROGRESSING INTO THE REGION TONIGHT WILL GRADUALLY WEAKEN TUE/TUE NIGHT AS THE ROBUST UPPER LEVEL LOW (CENTERED IN WESTERN NE THIS AFTERNOON) TRACKS TO THE CENTRAL MS RIVER VALLEY BY SUNSET TUE AND TO THE DOORSTEP OF THE SOUTHERN APPALACHIANS BY SUNRISE WED. DESPITE HEIGHT FALLS IN ADVANCE OF THE APPROACHING UPPER LEVEL LOW LATE TUE INTO TUE NIGHT...WEAKENING SURFACE HIGH PRESSURE WILL REMAIN ANCHORED IN PLACE ACROSS THE MID-ATLANTIC STATES ON THE WESTERN (SUBSIDENT) SIDE OF A STALLED UPPER LEVEL LOW OVER THE CANADIAN MARITIMES. WITH A DRY AND SUBSIDENT COLUMN PERSISTING OVER CENTRAL NC...EXPECT MOSTLY SUNNY SKIES (ASIDE FROM SCATTERED DIURNAL CU WITH BASES 3500-4500 FT AGL) TO PREVAIL THROUGH TUE EVENING. TOP-DOWN MOISTENING /INCREASING CIRRUS/ CAN BE EXPECTED TUE NIGHT AS THE UPPER LEVEL LOW APPROACHES THE MOUNTAINS FROM THE WEST...THOUGH DRY CONDITIONS WILL PREVAIL GIVEN THAT THE BEST UPPER LEVEL FORCING WILL REMAIN UPSTREAM OVER THE TN VALLEY AND A DRY LOW-LEVEL AIRMASS /LITTLE OR NO WAA/ WILL PERSIST OVER CENTRAL NC. EXPECT HIGHS SIMILAR TO ALBEIT SLIGHTLY WARMER THAN TODAY...IN THE MID 70S...WITH LOWS TUE NIGHT RANGING FROM THE MID 50S (WEST) TO UPPER 40S EAST...ONCE AGAIN DEPENDENT PRIMARILY UPON CLOUD COVER. -VINCENT && .LONG TERM /WEDNESDAY THROUGH MONDAY/... AS OF 245 PM MONDAY... CONFIDENCE IN AN UNSETTLED PATTERN FOR WEDNESDAY INTO A PORTION OF THURSDAY HAS INCREASED A BIT TODAY. MOST MODELS ARE INDICATING A MID/UPPER TROUGH AMPLIFICATION OVER THE EASTERN STATES... SHIFTING OFFSHORE LATE WEEK. THE IMPORTANT SURFACE WAVE IS STILL SUPPORTED TO DEVELOP/TRACK WELL TO OUR SOUTH AND EAST... FROM THE GULF COAST 12Z WEDNESDAY... EAST ACROSS NORTHERN FLORIDA EARLY THURSDAY... THEN OFF THE SOUTH ATLANTIC COAST FRIDAY. THE EC CONTINUES TO BE THE FAVORED MODEL OF CHOICE CONCERNING OPERATIONAL RUNS DUE TO ITS CONSISTENCY WITH THE EVOLUTION OF THE SYSTEM IN RECENT DAYS THROUGH TODAY. MOST OF THE HEAVY RAIN WITH THIS SYSTEM SHOULD BE CONFINED TO THE DEEP SOUTH AND POSSIBLY INTO SC AS THE MAIN LOW LEVEL BOUNDARY WILL BE HUNG UP THERE. HOWEVER... THERE IS STILL A GOOD CHANCE OF RAIN WITH THE MID/UPPER SUPPORT ALONG WITH ISENTROPIC LIFT WED-WED NIGHT. AFTER THE LOW MOVES OFFSHORE... ANOTHER MID/UPPER LOW MAY AGAIN TARGET THE GREAT LAKES AND MIDWEST SUPPORTED BY TELECONNECTIONS WITH THE NE PAC UPPER TROUGH... AND DOWNSTREAM UPPER RIDGE DEVELOPMENT OVER THE ROCKIES. THIS MAY LEAD TO MORE IN THE WAY OF UNSETTLED CONDITIONS LATER SUNDAY INTO EARLY NEXT WEEK. SENSIBLE WEATHER FOR CENTRAL NC SHOULD CONSIST OF THE HIGHEST CHANCES OF RAIN ON WEDNESDAY INTO WEDNESDAY NIGHT... ASSOCIATED WITH THE MID/UPPER TROUGH. THEN THE HIGHEST POP IN THE EAST ON THURSDAY (MAINLY MORNING) WITH THE SURFACE WAVE TRACKING TO OUR SOUTH AND EAST AND OFFSHORE THEN. IT IS STILL TOO EARLY TO FORECAST A FULL BLOWN COLD AIR DAMMING EVENT THAT WOULD BE OF IN-SITU OR POSSIBLY HYBRID NATURE WED INTO THU... GIVEN THE LACK OF A SUPPORTING PARENT SURFACE HIGH THAT WOULD BE STRONG ENOUGH... AND IN THE PREFERRED LOCATION FOR ANYTHING MORE IN OUR REGION. THE DEVELOPMENT OF AN IN-SITU OR WEAK HYBRID CAD EVENT SHOULD BE HIGHLY DEPENDENT BY THE QPF ON WED... WHICH IS STILL VERY MUCH IN QUESTION... AND IS STILL EXPECTED TO BE LESS THAN 0.25 OF AN INCH IN THE DAMMING REGION. DUE TO THE LACK OF CONFIDENCE ON ANYTHING MORE THAN 0.25 OF AN INCH OF RAIN WED-WED NIGHT AT THE CURRENT TIME... WE WILL MAINTAIN POP IN THE CHANCE TO HIGH CHANCE CATEGORY... QPF OF LESS THAN 0.25 OF AN INCH... AND TEMPERATURES (WHILE COOLER THAN NORMAL)... NOT BY MUCH (2-5 DEGREES OR SO FOR DAYTIME HIGHS). GIVEN THE EXPECTATION OF A WEAK CAD AT BEST... SKIES SHOULD CLEAR MORE QUICKLY LATE THU AND FRI AS THE STORM SHIFTS WELL OFFSHORE. LOWS WILL COOL INTO THE LOWER TO MID 50S FRI... WITH HIGHS IN THE MID 70S WITH MOSTLY SUNNY SKIES FRI. SAT-SUN... SKIES SHOULD CONTINUE MOSTLY CLEAR/MOSTLY SUNNY AS HIGH PRESSURE IS EXPECTED TO EXTEND DOWN THE EASTERN SEABOARD INTO SUNDAY. LOWS IN THE LOWER TO MID 50S AND HIGHS IN THE LOWER TO MID 70S ARE EXPECTED. SUNDAY NIGHT AND MONDAY... EXPECT SOME INCREASE IN CLOUDINESS FOR NOW... POSSIBLY A CHANCE OF RAIN AGAIN - BUT UNCERTAINTY THIS FAR OUT SUPPORTS A SLIGHT CHANCE OF SHOWERS IN THE FORECAST MONDAY. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... AS OF 1250 AM TUESDAY... REST OF TONIGHT: VFR STRATUS CONTINUES TO EXPAND IN AREA OVER CENTRAL VA INTO WRN NC... AND BASED ON THIS TREND APPEARS POISED TO SPREAD INTO INT/GSO AND PERHAPS RDU AS WELL OVERNIGHT. PATCHY VFR CLOUDS AFFECTED FAY EARLIER AND ADDITIONAL CLOUDS REMAIN POSSIBLE THROUGH DAYBREAK. MEANWHILE... BANKS OF SHALLOW DENSE FOG HAVE FORMED NEAR RWI -- PROMPTED BY THE NEARBY RIVER -- AND THIS FOG SHOULD PERSIST OVERNIGHT... WITH VSBYS MOSTLY IFR BUT VARYING BETWEEN LIFR AND MVFR THROUGH DAYBREAK. HRRR MODEL DEPICTS LOW IFR STRATUS SPREADING ACROSS ALL OF CENTRAL NC OVERNIGHT... AND WHILE THIS LOOKS OVERDONE... WE WILL KEEP A CLOSE EYE ON CLOUD TRENDS THROUGH THE REST OF THE NIGHT. AFTER 12Z: VFR THROUGH AT LEAST THIS EVENING. ANY MORNING STRATUS WILL MIX OUT BY 14Z WITH THE ONSET OF HEATING... THEN ANOTHER ROUND OF MOSTLY SCATTERED FLAT CUMULUS BASED AROUND 4000 FT AGL IS EXPECTED THIS AFTERNOON... AS THE MID/UPPER LEVELS STAY STABLE AND VERY DRY WHILE A THIN MOIST LAYER PERSISTS BENEATH THE SUBSIDENCE INVERSION ALOFT. THEN AFTER SUNSET... STABILIZING LOW LEVELS (LOWEST 4000 FT) AND VERY LIGHT WINDS WITH INCREASING NEAR-SURFACE MOISTURE WILL BRING A RISK OF MVFR FOG TONIGHT... ALTHOUGH THE BETTER CHANCE OF ADVERSE AVIATION CONDITIONS WILL HOLD OFF UNTIL AFTER 06Z TONIGHT. HIGH CLOUDS BASED ABOVE 15000 FT AGL WILL SPREAD IN FROM THE WEST TONIGHT. WINDS WILL BE VARIABLE IN DIRECTION THROUGH THE PERIOD AT SPEEDS UNDER 7 KTS. LOOKING BEYOND 06Z EARLY WEDNESDAY MORNING: PATCHY LOW STRATUS AND FOG ARE POSSIBLE THROUGH MID MORNING... PARTICULARLY NEAR BODIES OF WATER WHERE SHALLOW DENSE GROUND FOG MAY FORM PRIOR TO DAYBREAK. ANY SUCH CLOUDS SHOULD MIX OUT BEFORE 15Z WITH VFR CONDITIONS RETURNING... ALTHOUGH WE WILL SEE AN INCREASE IN STRATOCUMULUS BASED AROUND 3500 FT AGL ALONG WITH THICKENING AND LOWERING MID CLOUDS AS A STORM SYSTEM APPROACHES WEDNESDAY. IN GENERAL... VFR CONDITIONS WILL DOMINATE AS THIS SYSTEM CROSSES THE SOUTHEAST AND CAROLINAS... WITH CLOUD BASES MOSTLY ABOVE 3500 FT WITH LIGHT SHOWERS. THIS SYSTEM WILL EXIT ON THURSDAY WITH NEW HIGH PRESSURE RIDGING BUILDING IN AT THE SURFACE. SHALLOW FOG IS POSSIBLE EARLY FRIDAY MORNING WITH HIGH SURFACE RH AND LIGHT WINDS... BUT OTHERWISE EXPECT VFR CONDITIONS FRIDAY THROUGH SATURDAY BENEATH THE HIGH PRESSURE RIDGE. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...WSS SHORT TERM...VINCENT LONG TERM...BADGETT AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1252 AM EDT MON SEP 23 2013 .SYNOPSIS... A RIDGE OF HIGH PRESSURE SITTING OVER THE REGION WILL GRADUALLY WEAKEN TODAY AND TONIGHT. A LOW PRESSURE SYSTEM WILL CROSS THE SOUTHEAST STATES WEDNESDAY AND WEDNESDAY NIGHT... AS AN UPPER LEVEL TROUGH TRACKS ACROSS THE CAROLINAS. HIGH PRESSURE WILL BUILD BACK INTO THE REGION THURSDAY AND FRIDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 930 PM MONDAY... LAYER OF STRATOCU THAT WAS FAIRLY PREVALENT ACROSS CENTRAL NC THIS AFTERNOON DISSIPATED WITH THE LOSS OF HEATING. AN AREA OF HIGH PRESSURE AT THE SURFACE AND ALOFT WILL PERSIST ACROSS THE FORECAST AREA OVERNIGHT INTO TUESDAY MORNING. THIS WEATHER PATTERN USUALLY SIGNALS A SEASONABLY COOL AND DRY FORECAST. THIS SEEMS PLAUSIBLE AS SFC DEWPOINTS THIS AFTERNOON WERE IN THE UPPER 40S TO LOWER 50S. EXPECT COMPARABLE MIN TEMPS TONIGHT WITH MID 40S POSSIBLE IN THE NORMALLY COLDER LOCATIONS (SUCH AS NEW HILL...LOUISBURG... HENDERSON...ETC.) EXCEPTION TO THIS MAY BE THE FAR WESTERN PIEDMONT WHERE MODEL GUIDANCE CONTINUES TO SUGGEST A SHALLOW LAYER OF MOISTURE CENTERED JUST BELOW 850MB. 00Z GSO SOUNDING DEPICTS 2 DEG C DEWPOINT SPREAD AT THAT LEVEL. THIS MOIST LAYER COUPLED WITH LIFT GENERATED BY WEAK LOW LEVEL WAA WHICH MAY RESULT IN A LAYER OF STRATUS OVERNIGHT. IF CLOUDS DO DEVELOP...THIS WILL ACT AS A BLANKET AND REDUCE THE HEAT LOSS AT THE SURFACE RESULTING IN WARMER TEMPS. INHERITED A FORECAST OF MID 50S ALONG YADKIN RIVER VALLEY/NW PIEDMONT. DUE TO LACK OF CLOUDS EARLY THIS EVENING AND WINDS NEAR CALM...POTENTIAL FOR TEMPS TO COOL A BIT LOWER. ADJUSTED MIN TEMPS TO THE LOWER 50S IN THE TRIAD REGION. && .SHORT TERM /TUESDAY AND TUESDAY NIGHT/... AS OF 325 PM MONDAY... THE SHORTWAVE RIDGE PROGRESSING INTO THE REGION TONIGHT WILL GRADUALLY WEAKEN TUE/TUE NIGHT AS THE ROBUST UPPER LEVEL LOW (CENTERED IN WESTERN NE THIS AFTERNOON) TRACKS TO THE CENTRAL MS RIVER VALLEY BY SUNSET TUE AND TO THE DOORSTEP OF THE SOUTHERN APPALACHIANS BY SUNRISE WED. DESPITE HEIGHT FALLS IN ADVANCE OF THE APPROACHING UPPER LEVEL LOW LATE TUE INTO TUE NIGHT...WEAKENING SURFACE HIGH PRESSURE WILL REMAIN ANCHORED IN PLACE ACROSS THE MID-ATLANTIC STATES ON THE WESTERN (SUBSIDENT) SIDE OF A STALLED UPPER LEVEL LOW OVER THE CANADIAN MARITIMES. WITH A DRY AND SUBSIDENT COLUMN PERSISTING OVER CENTRAL NC...EXPECT MOSTLY SUNNY SKIES (ASIDE FROM SCATTERED DIURNAL CU WITH BASES 3500-4500 FT AGL) TO PREVAIL THROUGH TUE EVENING. TOP-DOWN MOISTENING /INCREASING CIRRUS/ CAN BE EXPECTED TUE NIGHT AS THE UPPER LEVEL LOW APPROACHES THE MOUNTAINS FROM THE WEST...THOUGH DRY CONDITIONS WILL PREVAIL GIVEN THAT THE BEST UPPER LEVEL FORCING WILL REMAIN UPSTREAM OVER THE TN VALLEY AND A DRY LOW-LEVEL AIRMASS /LITTLE OR NO WAA/ WILL PERSIST OVER CENTRAL NC. EXPECT HIGHS SIMILAR TO ALBEIT SLIGHTLY WARMER THAN TODAY...IN THE MID 70S...WITH LOWS TUE NIGHT RANGING FROM THE MID 50S (WEST) TO UPPER 40S EAST...ONCE AGAIN DEPENDENT PRIMARILY UPON CLOUD COVER. -VINCENT && .LONG TERM /WEDNESDAY THROUGH MONDAY/... AS OF 245 PM MONDAY... CONFIDENCE IN AN UNSETTLED PATTERN FOR WEDNESDAY INTO A PORTION OF THURSDAY HAS INCREASED A BIT TODAY. MOST MODELS ARE INDICATING A MID/UPPER TROUGH AMPLIFICATION OVER THE EASTERN STATES... SHIFTING OFFSHORE LATE WEEK. THE IMPORTANT SURFACE WAVE IS STILL SUPPORTED TO DEVELOP/TRACK WELL TO OUR SOUTH AND EAST... FROM THE GULF COAST 12Z WEDNESDAY... EAST ACROSS NORTHERN FLORIDA EARLY THURSDAY... THEN OFF THE SOUTH ATLANTIC COAST FRIDAY. THE EC CONTINUES TO BE THE FAVORED MODEL OF CHOICE CONCERNING OPERATIONAL RUNS DUE TO ITS CONSISTENCY WITH THE EVOLUTION OF THE SYSTEM IN RECENT DAYS THROUGH TODAY. MOST OF THE HEAVY RAIN WITH THIS SYSTEM SHOULD BE CONFINED TO THE DEEP SOUTH AND POSSIBLY INTO SC AS THE MAIN LOW LEVEL BOUNDARY WILL BE HUNG UP THERE. HOWEVER... THERE IS STILL A GOOD CHANCE OF RAIN WITH THE MID/UPPER SUPPORT ALONG WITH ISENTROPIC LIFT WED-WED NIGHT. AFTER THE LOW MOVES OFFSHORE... ANOTHER MID/UPPER LOW MAY AGAIN TARGET THE GREAT LAKES AND MIDWEST SUPPORTED BY TELECONNECTIONS WITH THE NE PAC UPPER TROUGH... AND DOWNSTREAM UPPER RIDGE DEVELOPMENT OVER THE ROCKIES. THIS MAY LEAD TO MORE IN THE WAY OF UNSETTLED CONDITIONS LATER SUNDAY INTO EARLY NEXT WEEK. SENSIBLE WEATHER FOR CENTRAL NC SHOULD CONSIST OF THE HIGHEST CHANCES OF RAIN ON WEDNESDAY INTO WEDNESDAY NIGHT... ASSOCIATED WITH THE MID/UPPER TROUGH. THEN THE HIGHEST POP IN THE EAST ON THURSDAY (MAINLY MORNING) WITH THE SURFACE WAVE TRACKING TO OUR SOUTH AND EAST AND OFFSHORE THEN. IT IS STILL TOO EARLY TO FORECAST A FULL BLOWN COLD AIR DAMMING EVENT THAT WOULD BE OF IN-SITU OR POSSIBLY HYBRID NATURE WED INTO THU... GIVEN THE LACK OF A SUPPORTING PARENT SURFACE HIGH THAT WOULD BE STRONG ENOUGH... AND IN THE PREFERRED LOCATION FOR ANYTHING MORE IN OUR REGION. THE DEVELOPMENT OF AN IN-SITU OR WEAK HYBRID CAD EVENT SHOULD BE HIGHLY DEPENDENT BY THE QPF ON WED... WHICH IS STILL VERY MUCH IN QUESTION... AND IS STILL EXPECTED TO BE LESS THAN 0.25 OF AN INCH IN THE DAMMING REGION. DUE TO THE LACK OF CONFIDENCE ON ANYTHING MORE THAN 0.25 OF AN INCH OF RAIN WED-WED NIGHT AT THE CURRENT TIME... WE WILL MAINTAIN POP IN THE CHANCE TO HIGH CHANCE CATEGORY... QPF OF LESS THAN 0.25 OF AN INCH... AND TEMPERATURES (WHILE COOLER THAN NORMAL)... NOT BY MUCH (2-5 DEGREES OR SO FOR DAYTIME HIGHS). GIVEN THE EXPECTATION OF A WEAK CAD AT BEST... SKIES SHOULD CLEAR MORE QUICKLY LATE THU AND FRI AS THE STORM SHIFTS WELL OFFSHORE. LOWS WILL COOL INTO THE LOWER TO MID 50S FRI... WITH HIGHS IN THE MID 70S WITH MOSTLY SUNNY SKIES FRI. SAT-SUN... SKIES SHOULD CONTINUE MOSTLY CLEAR/MOSTLY SUNNY AS HIGH PRESSURE IS EXPECTED TO EXTEND DOWN THE EASTERN SEABOARD INTO SUNDAY. LOWS IN THE LOWER TO MID 50S AND HIGHS IN THE LOWER TO MID 70S ARE EXPECTED. SUNDAY NIGHT AND MONDAY... EXPECT SOME INCREASE IN CLOUDINESS FOR NOW... POSSIBLY A CHANCE OF RAIN AGAIN - BUT UNCERTAINTY THIS FAR OUT SUPPORTS A SLIGHT CHANCE OF SHOWERS IN THE FORECAST MONDAY. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... AS OF 1250 AM TUESDAY... REST OF TONIGHT: VFR STRATUS CONTINUES TO EXPAND IN AREA OVER CENTRAL VA INTO WRN NC... AND BASED ON THIS TREND APPEARS POISED TO SPREAD INTO INT/GSO AND PERHAPS RDU AS WELL OVERNIGHT. PATCHY VFR CLOUDS AFFECTED FAY EARLIER AND ADDITIONAL CLOUDS REMAIN POSSIBLE THROUGH DAYBREAK. MEANWHILE... BANKS OF SHALLOW DENSE FOG HAVE FORMED NEAR RWI -- PROMPTED BY THE NEARBY RIVER -- AND THIS FOG SHOULD PERSIST OVERNIGHT... WITH VSBYS MOSTLY IFR BUT VARYING BETWEEN LIFR AND MVFR THROUGH DAYBREAK. HRRR MODEL DEPICTS LOW IFR STRATUS SPREADING ACROSS ALL OF CENTRAL NC OVERNIGHT... AND WHILE THIS LOOKS OVERDONE... WE WILL KEEP A CLOSE EYE ON CLOUD TRENDS THROUGH THE REST OF THE NIGHT. AFTER 12Z: VFR THROUGH AT LEAST THIS EVENING. ANY MORNING STRATUS WILL MIX OUT BY 14Z WITH THE ONSET OF HEATING... THEN ANOTHER ROUND OF MOSTLY SCATTERED FLAT CUMULUS BASED AROUND 4000 FT AGL IS EXPECTED THIS AFTERNOON... AS THE MID/UPPER LEVELS STAY STABLE AND VERY DRY WHILE A THIN MOIST LAYER PERSISTS BENEATH THE SUBSIDENCE INVERSION ALOFT. THEN AFTER SUNSET... STABILIZING LOW LEVELS (LOWEST 4000 FT) AND VERY LIGHT WINDS WITH INCREASING NEAR-SURFACE MOISTURE WILL BRING A RISK OF MVFR FOG TONIGHT... ALTHOUGH THE BETTER CHANCE OF ADVERSE AVIATION CONDITIONS WILL HOLD OFF UNTIL AFTER 06Z TONIGHT. HIGH CLOUDS BASED ABOVE 15000 FT AGL WILL SPREAD IN FROM THE WEST TONIGHT. WINDS WILL BE VARIABLE IN DIRECTION THROUGH THE PERIOD AT SPEEDS UNDER 7 KTS. LOOKING BEYOND 06Z EARLY WEDNESDAY MORNING: PATCHY LOW STRATUS AND FOG ARE POSSIBLE THROUGH MID MORNING... PARTICULARLY NEAR BODIES OF WATER WHERE SHALLOW DENSE GROUND FOG MAY FORM PRIOR TO DAYBREAK. ANY SUCH CLOUDS SHOULD MIX OUT BEFORE 15Z WITH VFR CONDITIONS RETURNING... ALTHOUGH WE WILL SEE AN INCREASE IN STRATOCUMULUS BASED AROUND 3500 FT AGL ALONG WITH THICKENING AND LOWERING MID CLOUDS AS A STORM SYSTEM APPROACHES WEDNESDAY. IN GENERAL... VFR CONDITIONS WILL DOMINATE AS THIS SYSTEM CROSSES THE SOUTHEAST AND CAROLINAS... WITH CLOUD BASES MOSTLY ABOVE 3500 FT WITH LIGHT SHOWERS. THIS SYSTEM WILL EXIT ON THURSDAY WITH NEW HIGH PRESSURE RIDGING BUILDING IN AT THE SURFACE. SHALLOW FOG IS POSSIBLE EARLY FRIDAY MORNING WITH HIGH SURFACE RH AND LIGHT WINDS... BUT OTHERWISE EXPECT VFR CONDITIONS FRIDAY THROUGH SATURDAY BENEATH THE HIGH PRESSURE RIDGE. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...WSS SHORT TERM...VINCENT LONG TERM...BADGETT AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1018 PM CDT WED SEP 25 2013 .UPDATE... ISSUED AT 1013 PM CDT WED SEP 25 2013 LATE EVENING UPDATE MAINLY FOR POPS BASED ON CURRENT RADAR TRENDS. THUNDERSTORMS HAVE OVERSPREAD MUCH OF WESTERN NORTH DAKOTA. THUS FAR...STORMS HAVE REMAINED NON-SEVERE. CANNOT RULE OUT AN ISOLATED SEVERE STORM OVERNIGHT...MAINLY IN THE FORM OF WIND AS POTENTIAL EXISTS FOR STRONG FLOW ALOFT TO BE TRANSPORTED TO THE LOW LEVELS BRIEFLY. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 335 PM CDT WED SEP 25 2013 THE PRIMARY FORECAST CHALLENGE CONTINUES TO BE THE SEVERE WEATHER CHANCES ACROSS WESTERN AND NORTH CENTRAL NORTH DAKOTA TONIGHT. SHORT RANGE MODEL GUIDANCE CONTINUES TO PROG A SHORTWAVE TO LIFT NORTH ACROSS EASTERN MONTANA AND NORTHWESTERN NORTH DAKOTA TONIGHT. ITS ATTENDANT SURFACE TROUGH AXIS WILL TIGHTEN UP ACROSS WESTERN NORTH DAKOTA THIS EVENING AS A RESULT. FURTHERMORE...MODEL MUCAPE VALUES ARE FORECAST TO RANGE BETWEEN 200-400 J/KG WHILE DEEP LAYER SHEAR WILL BE UP TO 50 KNOTS. EVEN THOUGH INSTABILITY IS NOT TERRIBLY IMPRESSIVE...THE COMBINATION OF LOW-LEVEL MOISTURE CONVERGENCE AND HIGH SHEAR ENVIRONMENT WILL LIKELY BE ENOUGH TO GENERATE SEVERE THUNDERSTORMS THIS EVENING. THE LATEST 4KM WRF-NMM AND 3KM HRRR PROG AN MCS TO DEVELOP OVER SOUTHEASTERN MONTANA AROUND 01Z. THIS COMPLEX IS THEN PROGGED TO LIFT NORTH ACROSS WESTERN NORTH DAKOTA THIS EVENING. THE HI-RES MODELS ARE HINTING AT THE MCS MORPHING INTO AN MCV BY THE END OF ITS CYCLE...GENERATING MORE OF A WIND THREAT. HOWEVER...IF UPDRAFTS GET STRONG ENOUGH...LARGE HAIL CANNOT BE RULED OUT. CONTINUED TO INDICATE LARGE HAIL AND DAMAGING WINDS IN THE AFFECTED ZONES FOR TONIGHT. PRECIP CHANCES WILL TAPER OFF FROM SOUTH TO NORTH AS THE PARENT SHORTWAVE LIFTS INTO CANADA THURSDAY MORNING. DRY CONDITIONS ARE THEN EXPECTED OVER MOST OF THE CWA (SANS NORTHWESTERN NORTH DAKOTA) BY THURSDAY AFTERNOON. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 335 PM CDT WED SEP 25 2013 THE HIGHLIGHTS OF THE EXTENDED PERIOD ARE RAIN AND WIND THURSDAY THROUGH FRIDAY NIGHT. WIDESPREAD RAINFALL UP TO ONE INCH IS LIKELY FOR SOME PARTS OF NORTH DAKOTA THURSDAY MORNING THROUGH FRIDAY NIGHT. GUSTY WINDS AROUND 35 MPH ARE LIKELY ACROSS MUCH OF WESTERN AND CENTRAL NORTH DAKOTA THURSDAY AFTERNOON. STRONG FORCING AND AMPLE MOISTURE WILL LIKELY BE IN PLACE ACROSS THE REGION THURSDAY THROUGH FRIDAY THANKS TO A STRONG UPPER LEVEL JET...DEEP LONGWAVE TROUGH...AND ISALLOBARIC FORCING ALONG THE INVERTED TROUGH. SEVERAL UPPER LEVEL SHORTWAVE TROUGHS SHOULD EJECT OUT OF THE MAIN LONGWAVE TROUGH TO THE WEST. IT APPEARS ONE SHOULD ARRIVE ON OUR DOORSTEP WEDNESDAY NIGHT...THURSDAY NIGHT AND FRIDAY NIGHT. THIS WOULD TEND TO FAVOR PRECIPITATION ARRIVING IN WAVES WITH BREAKS IN BETWEEN. THERE IS SOME UNCERTAINTY BETWEEN THE MAJOR MODELS AS TO EXACT LOCATION OF THE HEAVIEST RAIN AND TIMING OF THE MAIN COLD FRONT PUSH OUT OF THE REGION. THE 12 UTC GFS AND 12 UTC ECMWF APPEAR TO BE SLIGHTLY SLOWER WITH THE EXIT OF THE SYSTEM AND THEREFORE PRODUCE MORE PRECIP OVER WESTERN AND CENTRAL NORTH DAKOTA. THE 12 UTC GEM/NAM AND 09Z SREF HAVE THE BULK OF THE RAIN FALLING ACROSS EASTERN NORTH DAKOTA WITH THE FRONT PUSHING THROUGH EARLIER FRIDAY. THEREFORE...FOR THIS FORECAST ISSUANCE WENT WITH A BLEND OF THE MAJOR MODELS WITH A SLIGHT FAVOR TOWARD THE EASTWARD (FASTER) MODELS AS THE GFS HAS SHOWN A SLIGHT EASTWARD TREND OVER THE PAST FEW RUNS. DUE TO UNCERTAINTY DID NOT INCREASE CHANCES OF PRECIPITATION FOR THURSDAY OR FRIDAY. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING) ISSUED AT 627 PM CDT WED SEP 25 2013 MADE SOME MINOR ADJUSTMENTS TO TIMING OF SHOWERS/THUNDERSTORMS FOR THE 00Z TAFS. NOW EXPECTING IMPACTS AT KISN/KDIK BETWEEN 02Z- 03Z...KMOT AROUND 04Z...AND KBIS AROUND 09Z. MVFR CIGS ALSO EXPECTED OVERNIGHT. WINDS WILL BECOME WESTERLY AND GUST AROUND 30 KTS IN THE WAKE OF THE STRONG SURFACE LOW THAT WILL MOVE NORTH OF THE INTERNATIONAL BORDER THURSDAY MORNING. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE/AVIATION...RP KINNEY SHORT TERM...TM LONG TERM...AJ
AREA FORECAST DISCUSSION
NWS BISMARCK ND
646 PM CDT WED SEP 25 2013 .UPDATE... ISSUED AT 627 PM CDT WED SEP 25 2013 EVENING UPDATE MAINLY FOR MINOR CHANGES TO NEAR TERM POPS...OTHERWISE FORECAST IN GOOD SHAPE. THE BULK OF THE SHOWER/THUNDERSTORM COVERAGE TONIGHT IS EXPECTED TO STRETCH FROM THE SOUTHWEST THROUGH NORTH CENTRAL COUNTIES. STILL LOOKING FOR SOME STRONG/POSSIBLY SEVERE STORMS TO DEVELOP...ESPECIALLY FROM 01Z TO 06Z. WITH THE STRONG WINDS ALOFT...STEEP LOW LEVEL LAPSE RATES...AND DRY BOUNDARY LAYER...EXPECTED STRONG STRAIGHT LINE WINDS TO BE THE MAIN THREAT. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 335 PM CDT WED SEP 25 2013 THE PRIMARY FORECAST CHALLENGE CONTINUES TO BE THE SEVERE WEATHER CHANCES ACROSS WESTERN AND NORTH CENTRAL NORTH DAKOTA TONIGHT. SHORT RANGE MODEL GUIDANCE CONTINUES TO PROG A SHORTWAVE TO LIFT NORTH ACROSS EASTERN MONTANA AND NORTHWESTERN NORTH DAKOTA TONIGHT. ITS ATTENDANT SURFACE TROUGH AXIS WILL TIGHTEN UP ACROSS WESTERN NORTH DAKOTA THIS EVENING AS A RESULT. FURTHERMORE...MODEL MUCAPE VALUES ARE FORECAST TO RANGE BETWEEN 200-400 J/KG WHILE DEEP LAYER SHEAR WILL BE UP TO 50 KNOTS. EVEN THOUGH INSTABILITY IS NOT TERRIBLY IMPRESSIVE...THE COMBINATION OF LOW-LEVEL MOISTURE CONVERGENCE AND HIGH SHEAR ENVIRONMENT WILL LIKELY BE ENOUGH TO GENERATE SEVERE THUNDERSTORMS THIS EVENING. THE LATEST 4KM WRF-NMM AND 3KM HRRR PROG AN MCS TO DEVELOP OVER SOUTHEASTERN MONTANA AROUND 01Z. THIS COMPLEX IS THEN PROGGED TO LIFT NORTH ACROSS WESTERN NORTH DAKOTA THIS EVENING. THE HI-RES MODELS ARE HINTING AT THE MCS MORPHING INTO AN MCV BY THE END OF ITS CYCLE...GENERATING MORE OF A WIND THREAT. HOWEVER...IF UPDRAFTS GET STRONG ENOUGH...LARGE HAIL CANNOT BE RULED OUT. CONTINUED TO INDICATE LARGE HAIL AND DAMAGING WINDS IN THE AFFECTED ZONES FOR TONIGHT. PRECIP CHANCES WILL TAPER OFF FROM SOUTH TO NORTH AS THE PARENT SHORTWAVE LIFTS INTO CANADA THURSDAY MORNING. DRY CONDITIONS ARE THEN EXPECTED OVER MOST OF THE CWA (SANS NORTHWESTERN NORTH DAKOTA) BY THURSDAY AFTERNOON. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 335 PM CDT WED SEP 25 2013 THE HIGHLIGHTS OF THE EXTENDED PERIOD ARE RAIN AND WIND THURSDAY THROUGH FRIDAY NIGHT. WIDESPREAD RAINFALL UP TO ONE INCH IS LIKELY FOR SOME PARTS OF NORTH DAKOTA THURSDAY MORNING THROUGH FRIDAY NIGHT. GUSTY WINDS AROUND 35 MPH ARE LIKELY ACROSS MUCH OF WESTERN AND CENTRAL NORTH DAKOTA THURSDAY AFTERNOON. STRONG FORCING AND AMPLE MOISTURE WILL LIKELY BE IN PLACE ACROSS THE REGION THURSDAY THROUGH FRIDAY THANKS TO A STRONG UPPER LEVEL JET...DEEP LONGWAVE TROUGH...AND ISALLOBARIC FORCING ALONG THE INVERTED TROUGH. SEVERAL UPPER LEVEL SHORTWAVE TROUGHS SHOULD EJECT OUT OF THE MAIN LONGWAVE TROUGH TO THE WEST. IT APPEARS ONE SHOULD ARRIVE ON OUR DOORSTEP WEDNESDAY NIGHT...THURSDAY NIGHT AND FRIDAY NIGHT. THIS WOULD TEND TO FAVOR PRECIPITATION ARRIVING IN WAVES WITH BREAKS IN BETWEEN. THERE IS SOME UNCERTAINTY BETWEEN THE MAJOR MODELS AS TO EXACT LOCATION OF THE HEAVIEST RAIN AND TIMING OF THE MAIN COLD FRONT PUSH OUT OF THE REGION. THE 12 UTC GFS AND 12 UTC ECMWF APPEAR TO BE SLIGHTLY SLOWER WITH THE EXIT OF THE SYSTEM AND THEREFORE PRODUCE MORE PRECIP OVER WESTERN AND CENTRAL NORTH DAKOTA. THE 12 UTC GEM/NAM AND 09Z SREF HAVE THE BULK OF THE RAIN FALLING ACROSS EASTERN NORTH DAKOTA WITH THE FRONT PUSHING THROUGH EARLIER FRIDAY. THEREFORE...FOR THIS FORECAST ISSUANCE WENT WITH A BLEND OF THE MAJOR MODELS WITH A SLIGHT FAVOR TOWARD THE EASTWARD (FASTER) MODELS AS THE GFS HAS SHOWN A SLIGHT EASTWARD TREND OVER THE PAST FEW RUNS. DUE TO UNCERTAINTY DID NOT INCREASE CHANCES OF PRECIPITATION FOR THURSDAY OR FRIDAY. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING) ISSUED AT 627 PM CDT WED SEP 25 2013 MADE SOME MINOR ADJUSTMENTS TO TIMING OF SHOWERS/THUNDERSTORMS FOR THE 00Z TAFS. NOW EXPECTING IMPACTS AT KISN/KDIK BETWEEN 02Z- 03Z...KMOT AROUND 04Z...AND KBIS AROUND 09Z. MVFR CIGS ALSO EXPECTED OVERNIGHT. WINDS WILL BECOME WESTERLY AND GUST AROUND 30 KTS IN THE WAKE OF THE STRONG SURFACE LOW THAT WILL MOVE NORTH OF THE INTERNATIONAL BORDER THURSDAY MORNING. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE/AVIATION...RP KINNEY SHORT TERM...TM LONG TERM...AJ
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1245 PM CDT TUE SEP 24 2013 .UPDATE... ISSUED AT 1245 PM CDT TUE SEP 24 2013 NO MAJOR UPDATES WERE REQUIRED TO THE ONGOING FORECAST. ONLY ADJUSTED HOURLY SENSIBLE WEATHER GRIDS BASED ON CURRENT OBS/TRENDS. THE UPDATED PRODUCTS HAVE BEEN SENT. UPDATE ISSUED AT 947 AM CDT TUE SEP 24 2013 FOG HAS DISSIPATED ACROSS WESTERN AND CENTRAL NORTH DAKOTA THIS MORNING. AS A RESULT...REMOVED MORNING FOG WORDING FROM THE TEXT PRODUCTS. OTHERWISE...SUNNY SKIES ARE EXPECTED TODAY WITH HIGHS GENERALLY IN THE LOW 70S. THE UPDATED PRODUCTS HAVE BEEN SENT. UPDATE ISSUED AT 642 AM CDT TUE SEP 24 2013 LATEST SATELLITE IMAGERY AND SURFACE OBSERVATIONS INDICATE AREAS OF FOG ALONG THE MISSOURI RIVER FROM BISMARCK SOUTH TO THE SOUTH DAKOTA BORDER...AND EAST TOWARDS JAMESTOWN. ALSO AN AREA OF LOWER CLOUDS NOTED NEAR THE TURTLE MOUNTAINS. WILL CONTINUE A MENTION OF FOG FOR THESE AREAS THROUGH 15 UTC. OTHERWISE MAINLY CLEAR SKIES ACROSS WESTERN AND CENTRAL NORTH DAKOTA. SHOWERS THAT MOVED THROUGH THE AREA LAST NIGHT HAVE ALL BUT EXITED THE FAR SOUTHEAST CWA. UPDATED FORECAST LOWS WITH LATEST SENSIBLE WEATHER OBSERVATIONS. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 307 AM CDT TUE SEP 24 2013 LATEST WATER VAPOR IMAGERY SHOWS A SHORTWAVE TROUGH WORKING ITS WAY FROM CENTRAL NORTH DAKOTA INTO EASTERN NORTH DAKOTA. LOCAL RADAR AHEAD OF THIS TROUGH CONTINUES TO SHOW SCATTERED LIGHT SHOWERS FROM NEAR JAMESTOWN SOUTH TO ASHLEY AND EAST TO OAKES. THIS AREA WILL WANE THROUGH 12Z AS THE UPPER TROUGH EXITS THE COUNTY WARNING AREA. THE FOG/STRATUS LOOP INDICATES AN AREA OF FOG/LOW CLOUDS IN ADAMS AND HETTINGER COUNTIES. THE HRRR CLOUD CEILING HEIGHT IS ADVERTISING THIS AREA TO EXPAND SLIGHTLY AND SLIDE SOUTHEAST...BARELY CLIPPING BISMARCK THROUGH 15Z. HAVE FOLLOWED IT FOR THE SKY/WEATHER TRENDS EARLY THIS MORNING. OTHERWISE WARM AIR ADVECTION COMMENCES TODAY THROUGH TONIGHT. LARGE SCALE CONVERGENCE ALOFT WILL ALLOW FOR PLENTY OF SUNSHINE TODAY. WITH WARM AIR ADVECTION INCREASING TUESDAY NIGHT...A CHANGE TOWARD DIVERGENCE ALOFT ENSUES...ESPECIALLY OVER THE WEST/NORTHWEST. THE FAR NORTHWEST IS SUSCEPTIBLE TO AN ISOLATED SHOWER/THUNDERSTORM IN AFTER MIDNIGHT...OTHERWISE DRY WEATHER PREVAILS ELSEWHERE THROUGH THE SHORT TERM PERIOD. H85 TEMPS BETWEEN +12C TO +16C WILL YIELD AFTERNOON HIGHS IN THE UPPER 60S NORTH TO LOWER 70S SOUTH AND WEST. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 307 AM CDT TUE SEP 24 2013 THE MAIN FORECAST ISSUES IN THE LONG TERM WILL BE ASSOCIATED WITH A STRONG UPPER LEVEL TROUGH THAT TAKES SHAPE OVER THE NORTHWEST U.S. OVER THE NEXT 24 HOURS...AND TRACKS INTO THE NORTHERN HIGH PLAINS BY THE END OF THE WORK WEEK. CURRENTLY...UPPER LEVEL CIRCULATION CAN BE SEEN OFF THE BRITISH COLUMBIA COAST WITH A STRONG SHORTWAVE TROUGH OVER THE EASTERN PACIFIC...OFF THE NORTHERN CALIFORNIA COAST AND MATCHES WITH DETERMINISTIC MODELS. THE STRONG SHORTWAVE TROUGH WILL BE THE FIRST TO INFLUENCE OUR WEATHER AS IT MOVES ACROSS THE NORTHERN ROCKIES. STRONG SURFACE LOW PRESSURE DEVELOPS OVER EASTERN MONTANA BY TUESDAY NIGHT WITH INCREASING SOUTHERLY WINDS OVER WESTERN AND CENTRAL NORTH DAKOTA. THIS WILL BRING A SMALL CHANCE OF THUNDERSTORMS TO THE FAR WEST AND NORTHWEST DURING THE DAY ON WEDNESDAY. THUNDERSTORM CHANCES WILL INCREASE WEDNESDAY NIGHT INTO THURSDAY AS THE SURFACE LOW SLOWS DOWN AND TRACKS FROM WESTERN INTO CENTRAL NORTH DAKOTA DUE TO A STRONG UPPER LEVEL JET ROUNDING THE BASE OF THE MAIN UPPER LEVEL LOW AS IT MOVES INTO THE NORTHERN ROCKIES. INCREASING UPPER LEVEL JET DYNAMICS ACROSS THE NORTHERN HIGH PLAINS COULD SUPPORT SCATTERED SEVERE STORMS THAT WOULD THEN TRACK INTO THE WESTERN DAKOTAS. THUNDERSTORMS ARE EXPECTED TO BECOME ELEVATED LATE WEDNESDAY NIGHT INTO THURSDAY MORNING WITH A STRONG LOW LEVEL JET LIFTING INTO CENTRAL NORTH DAKOTA. THE GREATEST THREAT FOR THUNDERSTORMS WILL BE ACROSS FAR WESTERN AND NORTH CENTRAL NORTH DAKOTA WEDNESDAY NIGHT THROUGH THURSDAY MORNING...ALTHOUGH WITH SUCH STRONG DYNAMICS...SCATTERED THUNDERSTORMS CANNOT BE RULED OUT OVER CENTRAL NORTH DAKOTA. DETERMINISTIC MODELS ARE ALL DEPICTING A BREAK IN THE ACTION BEHIND THE INITIAL STRONG SHORTWAVE THURSDAY AFTERNOON INTO THURSDAY EVENING...BEFORE THE MAIN UPPER LEVEL LOW LIFTS INTO THE NORTHERN PLAINS. PRECIPITATION CHANCES THEN INCREASE LATE THURSDAY NIGHT THROUGH FRIDAY AS THE UPPER LEVEL TROUGH MOVES INTO THE NORTHERN PLAINS. THERE ARE SOME DIFFERENCES IN QPF BETWEEN THE WETTER ECMWF AND DRIER GFS/GEM ON FRIDAY. BY THIS TIME THE LOW LEVEL FLOW HAS SHIFTED NORTH OVER ALL BUT THE FAR SOUTHEAST CWA AND PRECIPITATION IS EXPECTED TO BE SHOWERS WITH PERHAPS AN ISOLATED THUNDERSTORM. THUNDERSTORM CHANCES WILL REMAIN OVER THE FAR SOUTHEAST FRIDAY NIGHT BEHIND THE SURFACE BOUNDARY AND JUST AHEAD OF THE UPPER LEVEL TROUGH. UPPER LEVEL RIDGING THEN BUILDS OVER THE REGION BRINGING DRY CONDITIONS OVER THE WEEKEND AND INTO EARLY NEXT WEEK. TEMPERATURES MAINLY IN THE 70S AHEAD OF THE MAIN COLD FRONT WEDNESDAY WILL COOL INTO THE 50S AND 60S ACROSS THE AREA BY FRIDAY. THEN A WARM-UP BACK INTO THE 70S IS EXPECTED BY SUNDAY AND MONDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON) ISSUED AT 1245 PM CDT TUE SEP 24 2013 VFR CONDITIONS WILL PREVAIL OVER WESTERN AND CENTRAL NORTH DAKOTA THROUGH THE TAF PERIOD. A SOUTHERLY LOW-LEVEL JET UP TO 50 KNOTS AT 3000 FT WILL SET UP OVER WESTERN NORTH DAKOTA (KDIK-KISN) AFTER 05Z TONIGHT. SINCE SOME OF THIS WIND IS FORECAST TO TRANSFER TO THE SURFACE...DID NOT INCLUDE NON-CONVECTIVE LOW-LEVEL WIND SHEAR IN THE KDIK-KISN TAFS. GUSTY SURFACE WINDS UP TO 25 KNOTS WILL CONTINUE TO SPREAD EAST INTO KMOT-KBIS-KJMS THROUGH WEDNESDAY MORNING. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...TM SHORT TERM...KS LONG TERM...TWH AVIATION...TM
AREA FORECAST DISCUSSION
NWS BISMARCK ND
947 AM CDT TUE SEP 24 2013 .UPDATE... ISSUED AT 947 AM CDT TUE SEP 24 2013 FOG HAS DISSIPATED ACROSS WESTERN AND CENTRAL NORTH DAKOTA THIS MORNING. AS A RESULT...REMOVED MORNING FOG WORDING FROM THE TEXT PRODUCTS. OTHERWISE...SUNNY SKIES ARE EXPECTED TODAY WITH HIGHS GENERALLY IN THE LOW 70S. THE UPDATED PRODUCTS HAVE BEEN SENT. UPDATE ISSUED AT 642 AM CDT TUE SEP 24 2013 LATEST SATELLITE IMAGERY AND SURFACE OBSERVATIONS INDICATE AREAS OF FOG ALONG THE MISSOURI RIVER FROM BISMARCK SOUTH TO THE SOUTH DAKOTA BORDER...AND EAST TOWARDS JAMESTOWN. ALSO AN AREA OF LOWER CLOUDS NOTED NEAR THE TURTLE MOUNTAINS. WILL CONTINUE A MENTION OF FOG FOR THESE AREAS THROUGH 15 UTC. OTHERWISE MAINLY CLEAR SKIES ACROSS WESTERN AND CENTRAL NORTH DAKOTA. SHOWERS THAT MOVED THROUGH THE AREA LAST NIGHT HAVE ALL BUT EXITED THE FAR SOUTHEAST CWA. UPDATED FORECAST LOWS WITH LATEST SENSIBLE WEATHER OBSERVATIONS. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 307 AM CDT TUE SEP 24 2013 LATEST WATER VAPOR IMAGERY SHOWS A SHORTWAVE TROUGH WORKING ITS WAY FROM CENTRAL NORTH DAKOTA INTO EASTERN NORTH DAKOTA. LOCAL RADAR AHEAD OF THIS TROUGH CONTINUES TO SHOW SCATTERED LIGHT SHOWERS FROM NEAR JAMESTOWN SOUTH TO ASHLEY AND EAST TO OAKES. THIS AREA WILL WANE THROUGH 12Z AS THE UPPER TROUGH EXITS THE COUNTY WARNING AREA. THE FOG/STRATUS LOOP INDICATES AN AREA OF FOG/LOW CLOUDS IN ADAMS AND HETTINGER COUNTIES. THE HRRR CLOUD CEILING HEIGHT IS ADVERTISING THIS AREA TO EXPAND SLIGHTLY AND SLIDE SOUTHEAST...BARELY CLIPPING BISMARCK THROUGH 15Z. HAVE FOLLOWED IT FOR THE SKY/WEATHER TRENDS EARLY THIS MORNING. OTHERWISE WARM AIR ADVECTION COMMENCES TODAY THROUGH TONIGHT. LARGE SCALE CONVERGENCE ALOFT WILL ALLOW FOR PLENTY OF SUNSHINE TODAY. WITH WARM AIR ADVECTION INCREASING TUESDAY NIGHT...A CHANGE TOWARD DIVERGENCE ALOFT ENSUES...ESPECIALLY OVER THE WEST/NORTHWEST. THE FAR NORTHWEST IS SUSCEPTIBLE TO AN ISOLATED SHOWER/THUNDERSTORM IN AFTER MIDNIGHT...OTHERWISE DRY WEATHER PREVAILS ELSEWHERE THROUGH THE SHORT TERM PERIOD. H85 TEMPS BETWEEN +12C TO +16C WILL YIELD AFTERNOON HIGHS IN THE UPPER 60S NORTH TO LOWER 70S SOUTH AND WEST. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 307 AM CDT TUE SEP 24 2013 THE MAIN FORECAST ISSUES IN THE LONG TERM WILL BE ASSOCIATED WITH A STRONG UPPER LEVEL TROUGH THAT TAKES SHAPE OVER THE NORTHWEST U.S. OVER THE NEXT 24 HOURS...AND TRACKS INTO THE NORTHERN HIGH PLAINS BY THE END OF THE WORK WEEK. CURRENTLY...UPPER LEVEL CIRCULATION CAN BE SEEN OFF THE BRITISH COLUMBIA COAST WITH A STRONG SHORTWAVE TROUGH OVER THE EASTERN PACIFIC...OFF THE NORTHERN CALIFORNIA COAST AND MATCHES WITH DETERMINISTIC MODELS. THE STRONG SHORTWAVE TROUGH WILL BE THE FIRST TO INFLUENCE OUR WEATHER AS IT MOVES ACROSS THE NORTHERN ROCKIES. STRONG SURFACE LOW PRESSURE DEVELOPS OVER EASTERN MONTANA BY TUESDAY NIGHT WITH INCREASING SOUTHERLY WINDS OVER WESTERN AND CENTRAL NORTH DAKOTA. THIS WILL BRING A SMALL CHANCE OF THUNDERSTORMS TO THE FAR WEST AND NORTHWEST DURING THE DAY ON WEDNESDAY. THUNDERSTORM CHANCES WILL INCREASE WEDNESDAY NIGHT INTO THURSDAY AS THE SURFACE LOW SLOWS DOWN AND TRACKS FROM WESTERN INTO CENTRAL NORTH DAKOTA DUE TO A STRONG UPPER LEVEL JET ROUNDING THE BASE OF THE MAIN UPPER LEVEL LOW AS IT MOVES INTO THE NORTHERN ROCKIES. INCREASING UPPER LEVEL JET DYNAMICS ACROSS THE NORTHERN HIGH PLAINS COULD SUPPORT SCATTERED SEVERE STORMS THAT WOULD THEN TRACK INTO THE WESTERN DAKOTAS. THUNDERSTORMS ARE EXPECTED TO BECOME ELEVATED LATE WEDNESDAY NIGHT INTO THURSDAY MORNING WITH A STRONG LOW LEVEL JET LIFTING INTO CENTRAL NORTH DAKOTA. THE GREATEST THREAT FOR THUNDERSTORMS WILL BE ACROSS FAR WESTERN AND NORTH CENTRAL NORTH DAKOTA WEDNESDAY NIGHT THROUGH THURSDAY MORNING...ALTHOUGH WITH SUCH STRONG DYNAMICS...SCATTERED THUNDERSTORMS CANNOT BE RULED OUT OVER CENTRAL NORTH DAKOTA. DETERMINISTIC MODELS ARE ALL DEPICTING A BREAK IN THE ACTION BEHIND THE INITIAL STRONG SHORTWAVE THURSDAY AFTERNOON INTO THURSDAY EVENING...BEFORE THE MAIN UPPER LEVEL LOW LIFTS INTO THE NORTHERN PLAINS. PRECIPITATION CHANCES THEN INCREASE LATE THURSDAY NIGHT THROUGH FRIDAY AS THE UPPER LEVEL TROUGH MOVES INTO THE NORTHERN PLAINS. THERE ARE SOME DIFFERENCES IN QPF BETWEEN THE WETTER ECMWF AND DRIER GFS/GEM ON FRIDAY. BY THIS TIME THE LOW LEVEL FLOW HAS SHIFTED NORTH OVER ALL BUT THE FAR SOUTHEAST CWA AND PRECIPITATION IS EXPECTED TO BE SHOWERS WITH PERHAPS AN ISOLATED THUNDERSTORM. THUNDERSTORM CHANCES WILL REMAIN OVER THE FAR SOUTHEAST FRIDAY NIGHT BEHIND THE SURFACE BOUNDARY AND JUST AHEAD OF THE UPPER LEVEL TROUGH. UPPER LEVEL RIDGING THEN BUILDS OVER THE REGION BRINGING DRY CONDITIONS OVER THE WEEKEND AND INTO EARLY NEXT WEEK. TEMPERATURES MAINLY IN THE 70S AHEAD OF THE MAIN COLD FRONT WEDNESDAY WILL COOL INTO THE 50S AND 60S ACROSS THE AREA BY FRIDAY. THEN A WARM-UP BACK INTO THE 70S IS EXPECTED BY SUNDAY AND MONDAY. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING) ISSUED AT 947 AM CDT TUE SEP 24 2013 VFR CIGS/VSBYS EXPECTED AT ALL AERODROMES FOR THE NEXT 24HR. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...TM SHORT TERM...KS LONG TERM...TWH AVIATION...TM
AREA FORECAST DISCUSSION
NWS BISMARCK ND
642 AM CDT TUE SEP 24 2013 .UPDATE... ISSUED AT 642 AM CDT TUE SEP 24 2013 LATEST SATELLITE IMAGERY AND SURFACE OBSERVATIONS INDICATE AREAS OF FOG ALONG THE MISSOURI RIVER FROM BISMARCK SOUTH TO THE SOUTH DAKOTA BORDER...AND EAST TOWARDS JAMESTOWN. ALSO AN AREA OF LOWER CLOUDS NOTED NEAR THE TURTLE MOUNTAINS. WILL CONTINUE A MENTION OF FOG FOR THESE AREAS THROUGH 15 UTC. OTHERWISE MAINLY CLEAR SKIES ACROSS WESTERN AND CENTRAL NORTH DAKOTA. SHOWERS THAT MOVED THROUGH THE AREA LAST NIGHT HAVE ALL BUT EXITED THE FAR SOUTHEAST CWA. UPDATED FORECAST LOWS WITH LATEST SENSIBLE WEATHER OBSERVATIONS. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 307 AM CDT TUE SEP 24 2013 LATEST WATER VAPOR IMAGERY SHOWS A SHORTWAVE TROUGH WORKING ITS WAY FROM CENTRAL NORTH DAKOTA INTO EASTERN NORTH DAKOTA. LOCAL RADAR AHEAD OF THIS TROUGH CONTINUES TO SHOW SCATTERED LIGHT SHOWERS FROM NEAR JAMESTOWN SOUTH TO ASHLEY AND EAST TO OAKES. THIS AREA WILL WANE THROUGH 12Z AS THE UPPER TROUGH EXITS THE COUNTY WARNING AREA. THE FOG/STRATUS LOOP INDICATES AN AREA OF FOG/LOW CLOUDS IN ADAMS AND HETTINGER COUNTIES. THE HRRR CLOUD CEILING HEIGHT IS ADVERTISING THIS AREA TO EXPAND SLIGHTLY AND SLIDE SOUTHEAST...BARELY CLIPPING BISMARCK THROUGH 15Z. HAVE FOLLOWED IT FOR THE SKY/WEATHER TRENDS EARLY THIS MORNING. OTHERWISE WARM AIR ADVECTION COMMENCES TODAY THROUGH TONIGHT. LARGE SCALE CONVERGENCE ALOFT WILL ALLOW FOR PLENTY OF SUNSHINE TODAY. WITH WARM AIR ADVECTION INCREASING TUESDAY NIGHT...A CHANGE TOWARD DIVERGENCE ALOFT ENSUES...ESPECIALLY OVER THE WEST/NORTHWEST. THE FAR NORTHWEST IS SUSCEPTIBLE TO AN ISOLATED SHOWER/THUNDERSTORM IN AFTER MIDNIGHT...OTHERWISE DRY WEATHER PREVAILS ELSEWHERE THROUGH THE SHORT TERM PERIOD. H85 TEMPS BETWEEN +12C TO +16C WILL YIELD AFTERNOON HIGHS IN THE UPPER 60S NORTH TO LOWER 70S SOUTH AND WEST. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 307 AM CDT TUE SEP 24 2013 THE MAIN FORECAST ISSUES IN THE LONG TERM WILL BE ASSOCIATED WITH A STRONG UPPER LEVEL TROUGH THAT TAKES SHAPE OVER THE NORTHWEST U.S. OVER THE NEXT 24 HOURS...AND TRACKS INTO THE NORTHERN HIGH PLAINS BY THE END OF THE WORK WEEK. CURRENTLY...UPPER LEVEL CIRCULATION CAN BE SEEN OFF THE BRITISH COLUMBIA COAST WITH A STRONG SHORTWAVE TROUGH OVER THE EASTERN PACIFIC...OFF THE NORTHERN CALIFORNIA COAST AND MATCHES WITH DETERMINISTIC MODELS. THE STRONG SHORTWAVE TROUGH WILL BE THE FIRST TO INFLUENCE OUR WEATHER AS IT MOVES ACROSS THE NORTHERN ROCKIES. STRONG SURFACE LOW PRESSURE DEVELOPS OVER EASTERN MONTANA BY TUESDAY NIGHT WITH INCREASING SOUTHERLY WINDS OVER WESTERN AND CENTRAL NORTH DAKOTA. THIS WILL BRING A SMALL CHANCE OF THUNDERSTORMS TO THE FAR WEST AND NORTHWEST DURING THE DAY ON WEDNESDAY. THUNDERSTORM CHANCES WILL INCREASE WEDNESDAY NIGHT INTO THURSDAY AS THE SURFACE LOW SLOWS DOWN AND TRACKS FROM WESTERN INTO CENTRAL NORTH DAKOTA DUE TO A STRONG UPPER LEVEL JET ROUNDING THE BASE OF THE MAIN UPPER LEVEL LOW AS IT MOVES INTO THE NORTHERN ROCKIES. INCREASING UPPER LEVEL JET DYNAMICS ACROSS THE NORTHERN HIGH PLAINS COULD SUPPORT SCATTERED SEVERE STORMS THAT WOULD THEN TRACK INTO THE WESTERN DAKOTAS. THUNDERSTORMS ARE EXPECTED TO BECOME ELEVATED LATE WEDNESDAY NIGHT INTO THURSDAY MORNING WITH A STRONG LOW LEVEL JET LIFTING INTO CENTRAL NORTH DAKOTA. THE GREATEST THREAT FOR THUNDERSTORMS WILL BE ACROSS FAR WESTERN AND NORTH CENTRAL NORTH DAKOTA WEDNESDAY NIGHT THROUGH THURSDAY MORNING...ALTHOUGH WITH SUCH STRONG DYNAMICS...SCATTERED THUNDERSTORMS CANNOT BE RULED OUT OVER CENTRAL NORTH DAKOTA. DETERMINISTIC MODELS ARE ALL DEPICTING A BREAK IN THE ACTION BEHIND THE INITIAL STRONG SHORTWAVE THURSDAY AFTERNOON INTO THURSDAY EVENING...BEFORE THE MAIN UPPER LEVEL LOW LIFTS INTO THE NORTHERN PLAINS. PRECIPITATION CHANCES THEN INCREASE LATE THURSDAY NIGHT THROUGH FRIDAY AS THE UPPER LEVEL TROUGH MOVES INTO THE NORTHERN PLAINS. THERE ARE SOME DIFFERENCES IN QPF BETWEEN THE WETTER ECMWF AND DRIER GFS/GEM ON FRIDAY. BY THIS TIME THE LOW LEVEL FLOW HAS SHIFTED NORTH OVER ALL BUT THE FAR SOUTHEAST CWA AND PRECIPITATION IS EXPECTED TO BE SHOWERS WITH PERHAPS AN ISOLATED THUNDERSTORM. THUNDERSTORM CHANCES WILL REMAIN OVER THE FAR SOUTHEAST FRIDAY NIGHT BEHIND THE SURFACE BOUNDARY AND JUST AHEAD OF THE UPPER LEVEL TROUGH. UPPER LEVEL RIDGING THEN BUILDS OVER THE REGION BRINGING DRY CONDITIONS OVER THE WEEKEND AND INTO EARLY NEXT WEEK. TEMPERATURES MAINLY IN THE 70S AHEAD OF THE MAIN COLD FRONT WEDNESDAY WILL COOL INTO THE 50S AND 60S ACROSS THE AREA BY FRIDAY. THEN A WARM-UP BACK INTO THE 70S IS EXPECTED BY SUNDAY AND MONDAY. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING) ISSUED AT 642 AM CDT TUE SEP 24 2013 AREAS OF FOG STRETCH FROM KBIS TO AROUND KJMS. ALTHOUGH VSBYS RANGE BETWEEN LIFR/VLIFR...THE DEPTH OF THE FOG REMAINS SHALLOW. EXPECT A QUICK RETURN TO SKC/P6SM BY 15Z. OTHERWISE VFR CIGS/VSBYS EXPECTED AT ALL AERODROMES FOR THE NEXT 24HR. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...TWH SHORT TERM...KS LONG TERM...TWH AVIATION...KS
AREA FORECAST DISCUSSION
NWS BISMARCK ND
307 AM CDT TUE SEP 24 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 307 AM CDT TUE SEP 24 2013 LATEST WATER VAPOR IMAGERY SHOWS A SHORTWAVE TROUGH WORKING ITS WAY FROM CENTRAL NORTH DAKOTA INTO EASTERN NORTH DAKOTA. LOCAL RADAR AHEAD OF THIS TROUGH CONTINUES TO SHOW SCATTERED LIGHT SHOWERS FROM NEAR JAMESTOWN SOUTH TO ASHLEY AND EAST TO OAKES. THIS AREA WILL WANE THROUGH 12Z AS THE UPPER TROUGH EXITS THE COUNTY WARNING AREA. THE FOG/STRATUS LOOP INDICATES AN AREA OF FOG/LOW CLOUDS IN ADAMS AND HETTINGER COUNTIES. THE HRRR CLOUD CEILING HEIGHT IS ADVERTISING THIS AREA TO EXPAND SLIGHTLY AND SLIDE SOUTHEAST...BARELY CLIPPING BISMARCK THROUGH 15Z. HAVE FOLLOWED IT FOR THE SKY/WEATHER TRENDS EARLY THIS MORNING. OTHERWISE WARM AIR ADVECTION COMMENCES TODAY THROUGH TONIGHT. LARGE SCALE CONVERGENCE ALOFT WILL ALLOW FOR PLENTY OF SUNSHINE TODAY. WITH WARM AIR ADVECTION INCREASING TUESDAY NIGHT...A CHANGE TOWARD DIVERGENCE ALOFT ENSUES...ESPECIALLY OVER THE WEST/NORTHWEST. THE FAR NORTHWEST IS SUSCEPTIBLE TO AN ISOLATED SHOWER/THUNDERSTORM IN AFTER MIDNIGHT...OTHERWISE DRY WEATHER PREVAILS ELSEWHERE THROUGH THE SHORT TERM PERIOD. H85 TEMPS BETWEEN +12C TO +16C WILL YIELD AFTERNOON HIGHS IN THE UPPER 60S NORTH TO LOWER 70S SOUTH AND WEST. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 307 AM CDT TUE SEP 24 2013 THE MAIN FORECAST ISSUES IN THE LONG TERM WILL BE ASSOCIATED WITH A STRONG UPPER LEVEL TROUGH THAT TAKES SHAPE OVER THE NORTHWEST U.S. OVER THE NEXT 24 HOURS...AND TRACKS INTO THE NORTHERN HIGH PLAINS BY THE END OF THE WORK WEEK. CURRENTLY...UPPER LEVEL CIRCULATION CAN BE SEEN OFF THE BRITISH COLUMBIA COAST WITH A STRONG SHORTWAVE TROUGH OVER THE EASTERN PACIFIC...OFF THE NORTHERN CALIFORNIA COAST AND MATCHES WITH DETERMINISTIC MODELS. THE STRONG SHORTWAVE TROUGH WILL BE THE FIRST TO INFLUENCE OUR WEATHER AS IT MOVES ACROSS THE NORTHERN ROCKIES. STRONG SURFACE LOW PRESSURE DEVELOPS OVER EASTERN MONTANA BY TUESDAY NIGHT WITH INCREASING SOUTHERLY WINDS OVER WESTERN AND CENTRAL NORTH DAKOTA. THIS WILL BRING A SMALL CHANCE OF THUNDERSTORMS TO THE FAR WEST AND NORTHWEST DURING THE DAY ON WEDNESDAY. THUNDERSTORM CHANCES WILL INCREASE WEDNESDAY NIGHT INTO THURSDAY AS THE SURFACE LOW SLOWS DOWN AND TRACKS FROM WESTERN INTO CENTRAL NORTH DAKOTA DUE TO A STRONG UPPER LEVEL JET ROUNDING THE BASE OF THE MAIN UPPER LEVEL LOW AS IT MOVES INTO THE NORTHERN ROCKIES. INCREASING UPPER LEVEL JET DYNAMICS ACROSS THE NORTHERN HIGH PLAINS COULD SUPPORT SCATTERED SEVERE STORMS THAT WOULD THEN TRACK INTO THE WESTERN DAKOTAS. THUNDERSTORMS ARE EXPECTED TO BECOME ELEVATED LATE WEDNESDAY NIGHT INTO THURSDAY MORNING WITH A STRONG LOW LEVEL JET LIFTING INTO CENTRAL NORTH DAKOTA. THE GREATEST THREAT FOR THUNDERSTORMS WILL BE ACROSS FAR WESTERN AND NORTH CENTRAL NORTH DAKOTA WEDNESDAY NIGHT THROUGH THURSDAY MORNING...ALTHOUGH WITH SUCH STRONG DYNAMICS...SCATTERED THUNDERSTORMS CANNOT BE RULED OUT OVER CENTRAL NORTH DAKOTA. DETERMINISTIC MODELS ARE ALL DEPICTING A BREAK IN THE ACTION BEHIND THE INITIAL STRONG SHORTWAVE THURSDAY AFTERNOON INTO THURSDAY EVENING...BEFORE THE MAIN UPPER LEVEL LOW LIFTS INTO THE NORTHERN PLAINS. PRECIPITATION CHANCES THEN INCREASE LATE THURSDAY NIGHT THROUGH FRIDAY AS THE UPPER LEVEL TROUGH MOVES INTO THE NORTHERN PLAINS. THERE ARE SOME DIFFERENCES IN QPF BETWEEN THE WETTER ECMWF AND DRIER GFS/GEM ON FRIDAY. BY THIS TIME THE LOW LEVEL FLOW HAS SHIFTED NORTH OVER ALL BUT THE FAR SOUTHEAST CWA AND PRECIPITATION IS EXPECTED TO BE SHOWERS WITH PERHAPS AN ISOLATED THUNDERSTORM. THUNDERSTORM CHANCES WILL REMAIN OVER THE FAR SOUTHEAST FRIDAY NIGHT BEHIND THE SURFACE BOUNDARY AND JUST AHEAD OF THE UPPER LEVEL TROUGH. UPPER LEVEL RIDGING THEN BUILDS OVER THE REGION BRINGING DRY CONDITIONS OVER THE WEEKEND AND INTO EARLY NEXT WEEK. TEMPERATURES MAINLY IN THE 70S AHEAD OF THE MAIN COLD FRONT WEDNESDAY WILL COOL INTO THE 50S AND 60S ACROSS THE AREA BY FRIDAY. THEN A WARM-UP BACK INTO THE 70S IS EXPECTED BY SUNDAY AND MONDAY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT) ISSUED AT 1230 AM CDT TUE SEP 24 2013 VCFG WAS ADDED TO KMOT/KBIS AND KJMS THROUGH 15Z TUESDAY. WILL CONTINUE TO MONITOR BUT INDICATIONS ARE THAT LOW CLOUDS/FOG SHOULD REMAIN JUST SOUTH OF KBIS/KJMS AND NORTH OF KMOT. WILL CONTINUE TO MONITOR THE TRENDS AND ADJUST IF NECESSARY. OTHERWISE VFR CIGS/VSBYS ARE EXPECTED THROUGH THE PERIOD. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...KS LONG TERM...TWH AVIATION...KS
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1230 AM CDT TUE SEP 24 2013 .UPDATE... ISSUED AT 1230 AM CDT TUE SEP 24 2013 LATEST FOG/STRATUS IMAGERY ALONG WITH THE HRRR CLOUD HEIGHT FORECAST FOR THE REST OF THE NIGHT SHOWS AN AREA OF FOG/LOW CLOUDS DEVELOPING OVER FAR WESTERN SOUTH DAKOTA AND INTO ADAMS COUNTY NEAR HETTINGER. HAVE INCREASED CLOUDS AND ADDED IN A MENTION OF FOG THROUGH 15Z FOR PORTIONS OF SOUTH CENTRAL...WHERE THE RAIN HAD FALLEN EARLIER...AND ALSO OVER THE NORTH CENTRAL. ALSO DELAYED THE ENDING OF THE SHOWERS IN THE JAMES RIVER VALLEY AS LIGHT SHOWERS CONTINUE TO PERSIST. EXTENDED SHOWER CHANCES THROUGH 11Z TUESDAY BEFORE ENDING THE MENTION OF PRECIPITATION. UPDATE ISSUED AT 902 PM CDT MON SEP 23 2013 AT 9 PM CDT...BAND OF SHOWERS ACROSS CENTRAL NORTH DAKOTA CONTINUED TO GRADUALLY SHRINK. FOR THIS FORECAST UPDATE...REFINED THE SHOWER AREA. SHOWERS WILL PERSIST UNTIL MIDNIGHT CDT CENTRAL SECTIONS...SHRINKING SLOWLY. CLEARING SKIES ARE ENTERING THE WEST AT THIS TIME. TEMPERATURES AND WINDS LOOK GOOD SO FAR. UPDATE ISSUED AT 635 PM CDT MON SEP 23 2013 RAIN BAND TENDING TO BE AROUND 75 MILES WIDE ACROSS CENTRAL NORTH DAKOTA. THIS BAND IS TRANSLATING EAST AT THE SAME TIME IT IS DIMINISHING SLOWLY IN COVERAGE AND INTENSITY. DO NOT BELIEVE A SIGNIFICANT AMOUNT OF RAIN WILL REACH THE JAMES RIVER VALLEY TONIGHT BUT A CHANCE DOES REMAIN FOR SOME LIGHT RAIN THERE. SEE THE RAIN ENDING ACROSS THE CENTRAL BY 10 PM CDT. TRIED TO REFINE THE RAIN REGION IN THE LIKELY CATEGORY CENTRAL THROUGH THE MID EVENING, THEN QUICKLY DRY THE PRECIP AREA BY MIDNIGHT. OTHERWISE WILL SEE GRADUAL CLEARING. ENOUGH NORTHWEST FLOW BEHIND THE FRONT TO KEEP MIXING UP AND HAVE NOT CONSIDERED FOG LATER TONIGHT...ALTHOUGH WILL CONTINUE TO MONITOR. && .SHORT TERM...(THIS EVENING THROUGH TUESDAY) ISSUED AT 310 PM CDT MON SEP 23 2013 THE MAIN FORECAST CHALLENGE WILL BE THE TIMING OF A BAND OF RAIN SHOWERS MOVING EAST ACROSS WESTERN AND CENTRAL NORTH DAKOTA THIS AFTERNOON AND EVENING. THE LATEST SHORT RANGE MODEL GUIDANCE CONTINUES TO SLOW THE PROGRESSION OF THIS SYSTEM ACROSS THE REGION THIS AFTERNOON AND EVENING. RADAR TRENDS HAVE BEEN SUPPORTING THE LATEST MODEL PROGS SO ADJUSTED THE FORECAST ACCORDINGLY. FURTHERMORE...THE PRIMARY UPPER LEVEL LOW DRIVING THIS SYSTEM IS BEGINNING TO RACE AHEAD OF THIS BAND OF PRECIP...CUTTING OFF MUCH OF THE UPPER LEVEL SUPPORT. GIVEN THE SLOWER PROGRESSION AND SYNOPTIC EVOLUTION OF THE UPPER LOW...DECIDED TO LOWER POPS BY A CATEGORY OVER CENTRAL NORTH DAKOTA AS PRECIP INTENSITY AND COVERAGE IS NOW EXPECTED TO DECREASE AS THE AFTERNOON AND EVENING PROGRESSES. THE SURFACE TROUGH PROVIDING FOCUS FOR THIS PRECIPITATION SHOULD BE IN EASTERN NORTH DAKOTA AFTER MIDNIGHT TONIGHT. DRIER AIR IS PROGGED TO FILTER INTO WESTERN NORTH DAKOTA AFTER MIDNIGHT...WITH RADIATIONAL COOLING CONDITIONS DEVELOPING. THE RELATIVE LOW-LYING AREAS WEST COULD SEE LOWS IN THE UPPER 30S BY EARLY TUESDAY MORNING. DRY CONDITIONS AND SLIGHTLY ABOVE NORMAL TEMPERATURES (HIGHS IN THE LOW 70S) ARE FORECAST TUESDAY AS HIGH PRESSURE BUILDS INTO THE REGION. .LONG TERM...(TUESDAY NIGHT THROUGH MONDAY) ISSUED AT 310 PM CDT MON SEP 23 2013 THE HIGHLIGHT OF THE EXTENDED PERIOD IS THE POSSIBLE RAIN AND WIND WEDNESDAY THROUGH FRIDAY. AN UPPER LEVEL LONGWAVE TROUGH...CURRENTLY ENTERING THE PACIFIC NORTHWEST...SHOULD PUSH EAST INTO WESTERN MONTANA BY WEDNESDAY. AHEAD OF THE TROUGH...QUASI ZONAL FLOW WILL TRANSITION TO SOUTHWEST FLOW. THIS WILL IN TURN PROMOTE SURFACE LEE CYCLOGENESIS ACROSS THE EASTERN ROCKY MOUNTAIN RANGE IN WYOMING AND MONTANA. THIS LEE CYCLOGENESIS IS PROGGED TO DEVELOP INTO A LARGE INVERTED TROUGH CENTERED ACROSS NORTH DAKOTA AND ENCOMPASS MOST OF THE NORTHERN PLAINS. AS A RESULT OF THIS INVERTED TROUGH A STEEP PRESSURE GRADIENT IS PROGGED TO SETUP ACROSS THE DAKOTAS LATE WEDNESDAY INTO THURSDAY. WARM AIR ADVECTION SHOULD FURTHER ENHANCE THE MAGNITUDE OF PRESSURE DIFFERENCES FROM MONTANA TO MINNESOTA. THEREFORE WINDY CONDITIONS...30 MPH GUSTS...ARE POSSIBLE ACROSS MOST OF THE NORTHERN PLAINS WEDNESDAY THROUGH FRIDAY. ADDITIONALLY...STRONG LOW LEVEL WARM MOIST AIR RETURN AHEAD OF THE TROUGH SHOULD PROVIDE AMPLE MOISTURE RETURN TO FUEL WIDESPREAD SHOWERS AND THUNDERSTORMS ALONG THE WESTERN PERIPHERY OF THE INVERTED TROUGH. THE 12 UTC GFS AND ECMWF HAVE THE LONGWAVE TROUGH AND ASSOCIATED 100+ KNOT JET IN A FAVORABLE RAIN PRODUCING POSITION WEST OF NORTH DAKOTA THROUGH LATE FRIDAY. THEREFORE SCATTERED TO WIDESPREAD PRECIP IS POSSIBLE STARTING WEDNESDAY NIGHT AND LASTING THROUGH FRIDAY NIGHT. THE MOST LIKELY AREA FOR PROLONGED PRECIPITATION APPEARS TO BE ON ACROSS NORTHWESTERN AND NORTH CENTRAL NORTH DAKOTA. THIS IS THE AREA WHERE THE 12 UTC GFS/ECMWF/NAM HAVE THE BEST UPPER LEVEL JET DYNAMICS INTERACTING WITH STRONG ISENTROPIC AND ISALLOBARIC FORCING. SOME LOCATIONS ACROSS NORTHWEST AND NORTH CENTRAL NORTH DAKOTA COULD SEE LOCALLY HEAVY RAINFALL WEDNESDAY NIGHT THROUGH FRIDAY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT) ISSUED AT 1230 AM CDT TUE SEP 24 2013 VCFG WAS ADDED TO KMOT/KBIS AND KJMS THROUGH 15Z TUESDAY. WILL CONTINUE TO MONITOR BUT INDICATIONS ARE THAT LOW CLOUDS/FOG SHOULD REMAIN JUST SOUTH OF KBIS/KJMS AND NORTH OF KMOT. WILL CONTINUE TO MONITOR THE TRENDS AND ADJUST IF NECESSARY. OTHERWISE VFR CIGS/VSBYS ARE EXPECTED THROUGH THE PERIOD. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...KS SHORT TERM...TM LONG TERM...AJ AVIATION...KS
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
1142 PM CDT MON SEP 23 2013 .DISCUSSION... SEE 06Z AVIATION DISCUSSION. && .AVIATION... CIGS HAVE SCATTERED OUT THIS EVENING AND GENERALLY VFR CONDS PREVAIL AREAWIDE. SOME SHOWERS OVER THE GULF ARE ROTATING INTO SE TX FROM THE EAST. SHORT TERM MODELS CONTINUE TO SHOW SOME SHOWERS MOVING TOWARD THE COASTAL TAF SITES THROUGH THE MORNING SO ADDED A VCSH FOR KGLS. THE RAP CONTINUES TO SHOW AN EXPANDING AREA OF PRECIP NEAR THE COAST BETWEEN 13-16Z AND THIS SOLN GETS SOME WEAK SUPPORT FROM THE TEXAS TECH 3 KM WRF. THE HRRR AND HI RES NMM DO NOT SHOW THIS AREA OF PRECIP. VFR CONDS EXPECTED ON TUESDAY AFTN WITH CLEAR SKIES DEVELOPING AREA WIDE BY 00Z WEDNESDAY. 43 && .PREV DISCUSSION... /ISSUED 936 PM CDT MON SEP 23 2013/ UPDATE... SEE DISCUSSION FOR EVENING UPDATE. DISCUSSION... PARTLY CLOUDY SKIES ACROSS SOUTHEAST TEXAS THIS EVENING. CLOUDS HAVE STARTED TO BREAK BUT COOLING WILL BE LIMITED TONIGHT AS MOISTURE HAS STARTED TO WORK ITS WAY BACK INTO SOUTHEAST TEXAS. DEEP MOISTURE HAS REMAINED OFF THE COAST THOUGH WHICH THE GFS HAS DONE A PRETTY GOOD JOB FORECASTING. CURRENT PWATS ARE AROUND 2" AT KGLS WHILE AROUND 1.7" IN THE CITY OF HOUSTON. ANOTHER FRONT WILL WORK ITS WAY INTO THE AREA TUESDAY WHICH WILL MOST LIKELY BE A DRY FRONTAL PASSAGE. BETTER MOISTURE LAYS OFF TO THE NORTHEAST SO OUR FAR NORTHEASTERN COUNTIES MIGHT SEE SOME PRECIPITATION. BEHIND THE FRONT MUCH DRIER AIR WILL BE USHERED IN. PWAT VALUES FALL BELOW AN INCH AT KCLL BY 0Z WEDNESDAY IN BOTH GFS AND NAM SOUNDINGS. DUE TO THIS DRIER AIR AND A RELATIVELY WARM START TO THE DAY TOMORROW HIGH TEMPERATURES WILL LIKELY CLIMB INTO THE LOWER TO MID 90S. CURRENT FORECAST HAS THIS COVERED ONLY MADE MINOR TWEAKS TO GRIDS. 23 && PREV DISCUSSION... /ISSUED 319 PM CDT MON SEP 23 2013/ DISCUSSION... SFC ANALYSIS HAS LOW PRESSURE A COUPLE HUNDRED MILES OFF THE COAST SOUTH OF GALVESTON IN THE NW GULF. CONVECTION HAS BEEN A BIT MORE ORGANIZED AROUND AN ELONGATED CIRCULATION SEEN ON VIS SATELLITE IMAGERY. WATER VAPOR IMAGERY CONTINUES TO SHOW QUITE A BIT OF DRY AIR AROUND THE SYSTEM SO DO NOT SEE THERE BEING ANY TROPICAL DEVELOPMENT AT ALL WITH THIS SYSTEM. UPPER AIR ANALYSIS HAS UPPER LOW OVER THE ROCKIES WHICH HAS NOW PULLED INTO THE PLAINS PER WATER VAPOR IMAGERY. SUSPECT THIS ALONG WITH CYCLOGENESIS IN THE PLAINS WILL HELP TO TRY AND DRAW THE GULF CIRCULATION TOWARDS THE COAST TONIGHT INTO TOMORROW. FORECAST WILL KEEP SOME SMALL RAIN CHANCES ALONG THE COAST OVERNIGHT INTO TUE BUT REALLY NOT EXPECTED MUCH PRECIP FOR INLAND AREAS. UPPER LOW IN PLAINS SHOULD SHEAR OUT AND WEAKEN WITH THE NEGATIVE TILT TOMORROW INTO WED. THIS DOES ALLOW FOR A PACIFIC FRONT TO PUSH INTO THE AREA TOMORROW AND TUE NIGHT. THE MAIN EFFECT WILL BE TO PROVIDE SOME DRIER AIR FOR THE AREA SO LOOKS LIKE MAYBE A COUPLE MORE COOL MORNINGS BEFORE MOISTURE RETURN FLOW OFF THE GULF STARTS IN EARNEST BY THE END OF THE WEEK. UPPER LEVEL RIDGE SHOULD DEVELOP OVER THE AREA MID WEEK WITH A BROAD TROUGH DEVELOPING OVER THE GREAT BASIN AND ROCKIES. THE ECMWF/GFS/CANADIAN ARE IN A LITTLE MORE AGREEMENT WITH THIS TROUGHS EVOLUTION AND THIS WILL BE KEY WITH REGARDS TO THIS WEEKEND`S POTENTIAL COLD FRONT. UPPER TROUGH HAS ONE PIECE OF VORTICITY THAT MOVES INTO THE N PLAINS ON THUR WITH THE MAIN TROUGH LAGGING BACK OVER THE SIERRA NEVADAS ON THUR. THE MAIN UPPER LOW LAGS BACK OVER THE 4 CORNERS REGION INTO SAT BEFORE MOVING INTO THE PLAINS SAT NIGHT. THIS IS ABOUT 12-24 HRS SLOWER THAN THE PREVIOUS MODEL RUNS AND SEEMS LIKE ALL MODELS ARE TRENDING SLOWER WITH THE UPPER LOW. SO WITH THAT LOOKS LIKE THE COLD FRONT WILL BE SLOWER TO MOVE INTO THE AREA. WILL STILL KEEP 30 POPS AS THERE WILL BE GOOD MOISTURE AND THINK CONVECTION SHOULD DEVELOP FRI/SAT BUT BEST CHANCES STILL LOOK TO BE MORE ON SUNDAY. COLD FRONT IS SET TO PUSH THROUGH DURING THE DAY SUN PER GFS/ECMWF. MAIN PROBLEM WILL BE TO WATCH AND SEE IF THE FRONT STALLS BEFORE REACHING THE COAST. THIS MAY BE A POSSIBILITY SINCE THERE WILL BE SOME UPPER LEVEL RIDGING AND THE FRONT COULD BECOME MORE ORIENTED PARALLEL TO MEAN UPPER FLOW. THINK THIS MAY BE MORE THE CASE AND EXPECT TO SEE MODELS TREND IN THIS DIRECTION. 39 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 69 94 67 93 67 / 10 10 10 10 10 HOUSTON (IAH) 72 94 68 94 68 / 10 10 10 10 10 GALVESTON (GLS) 78 90 76 90 78 / 20 20 10 10 10 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL 1 AM CDT TUESDAY FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL OUT 20 NM...WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM. SMALL CRAFT ADVISORY UNTIL 1 AM CDT TUESDAY FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL 20 NM TO 60 NM...WATERS FROM HIGH ISLAND TO FREEPORT 20 TO 60 NM. SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL 4 AM CDT TUESDAY FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL 20 NM TO 60 NM...WATERS FROM HIGH ISLAND TO FREEPORT 20 TO 60 NM. && $$ DISCUSSION...23 AVIATION/MARINE...43
AREA FORECAST DISCUSSION
NWS SPOKANE WA
1136 AM PDT Tue Sep 24 2013 .SYNOPSIS... An upper level low will be the dominant weather feature through much of the week. this will result in rain showers and mountain snow showers at times through Thursday. Temperatures are expected to remain well below normal. A warming and drying trend is expected by the weekend. && .DISCUSSION... Morning update sent to fine tune Pops and QPF across the forecast area. Steady stream of showers/rain has setup where expected...generally from Pendleton to Pullman/Lewiston to Mullan. Main updates to these areas was to increase QPF amts with some heavier embedded cells producing 0.05" or more per hour. Satellite and radar indicate showers filling across the Spokane- CDA area and even as far northwest as Grand Coulee. Water Vapor and model data confirm a weak shortwave embedded within the SW flow and latest HRRR is handling the current situation. This would suggest showers will continue to fill in across NE WA and Nrn ID this morning impacting most communities from Republic to Bonners Ferry. This activity is more scattered in nature so not every point is a sure bet for rainfall. These showers are moving at a good rate so most precipitation amts will be less then 0.05". One other item of note via the latest HRRR is how convective showers trend after 20z across the entire region. As the trof settles into the region and 500mb cool...isolated showers will be possible for just about every location and we have increased even the lee of the Cascades to slight chance given the lack of a strong rain shadow. This will need to be monitored closely across the far southeast as any sunshine could deliver a few hundred joules of CAPE and potential for isolated storms producing heavy rainfall. /sb && .AVIATION... 18Z TAFS: Moisture associated with the Low continue to impact the region. The locations of KEAT and KMWH can expect a continue clearing as drier air fills in behind this system. This will keep these locations VFR for the period. A wind shift to the NW is expected around 11Z on Wednesday as this area will enter the backside of the trough. The Eastern portion of Washington and ID Panhandle will be the locations that are greatly impacted by the moisture. These locations will receive intermittent showers and ceilings and visibility varying from IFR to MVFR through the early afternoon hours. As the period progresses, this area will begin to be influence by the drier air moving into the region. /JDC && .PREV DISCUSSION... /ISSUED 435 AM PDT Tue Sep 24 2013/ SYNOPSIS... An upper level low will be the dominant weather feature through much of the week. this will result in rain showers and mountain snow showers at times through Thursday. Temperatures are expected to remain well below normal. A warming and drying trend is expected by the weekend. DISCUSSION... Tuesday and Tuesday night: A deep trof of low pressure will carve into the Pac NW bringing a continuation of below normal temperatures and unsettled weather. The most persistent area of precipitation will focus across far southeastern WA and the lower ID Panhandle however showers will be common across all mountains surrounding the deep Basin and expanding at times into the West Plains. As of 2AM...a line of showers has developed from Mullan to Pullman/Lewiston to Pendleton very close to where model guidance indicated over the last 48 hours. Rainfall rates under this band have generally be around 0.01 to 0.04" per hour. Expect this band to sit in place until late Tuesday afternoon/early evening with rainfall amounts spanning from a quarter to half an inch. Locally higher amounts could be possible over the Camas Prairie; especially if a few sun-breaks on Tuesday aftn add a convective element. Further north into the northeastern mountains of WA...Nrn ID Panhandle...and Spokane-CDA area...a combination of afternoon heating...orographics...and especially a shortwave passage during the afternoon will also bring the threat for widely scattered showers. This should be a bit more widespread and wetter then Tuesday given the potential shortwave dynamics and PoPs may need to be further increased for locations like Spokane...Deer Park... Coeur D Alene...Sandpoint...and Bonners Ferry. Will be taking a look at incoming HRRR runs and 12z guidance before deciding. By this evening and overnight...the upper-level trof will become firmly entrenched over the Pac NW. Cooling 500mb temperatures near -25C will promote steepening midlevel lapse rates. A pressure trof at the surface will begin to weaken and sag south and a cool high pressure cell slipping into BC will create northerly gradients across the CWA. This will draw cooler but drier air southward into the CWA leading to a decreasing shower trend and potential for locally gusty winds through the Okanogan Valley. A few of the northern valleys like Republic...Deer Park...and Priest Lake will be close to the freezing mark while most other lowlands dip into the upper 30`s to mid 40`s. /sb Wednesday and Wednesday Night: A closed low continues to pass to the south of our forecast area but will still present some unsettled conditions. Best chances for precipitation look to be Tomorrow Afternoon in the ID Panhandle pushing back west into the Blue Mtns. Rain showers will be the most likely mode of precipitation...but a couple claps of thunder cannot be ruled out with some weak instability in the Panhandle associated with the trof and closed low. Precip amounts look to be pretty limited with this system...but convective enhanced showers could bring moderate showers for localized areas. By Wednesday Night the trof will be pushing to the east limiting the overall chance for precipitation in our forecast area. Winds will be the main factor during this period with gusty conditions expected Wednesday for the Okanogan Valley. Winds from the north will channel down the valley enhancing the winds with gusts in the range of 25 to 30mph. The gusty conditions will continue down into the western Basin with values more in the 20 to 25mph range. The winds will be something to monitor throughout the day for the north-south oriented valleys in north Washington. Temperatures with the northerly flow will be below normal with upper 50s and low 60s for most locations minus the deep basin and lower valleys. Overnight lows will be in the 30s and low 40s for most of the region. Patchy frost was added for Wednesday Night as cold conditions will continue into the overnight hours. Main focus for frost will be the Republic area along with the Priest Lake and Deer Park areas. Fog will also be present in some valley locations. Any areas with fog will likely not see the frost as the fog will prevent strong radiational cooling. Snow levels will remain lower allowing high elevations in the Cascades and ID Panhandle to see some flurries...but no lasting accumulations are expected. /Fliehman Thursday through Monday...Model agreement is good and consistent Thursday through Saturday. The deep trough over the region will move off to the east on Thursday but some lingering shower activity will continue primarily over the Idaho Panhandle and possibly far eastern Washington. Temperatures will continue to run below normal and locally breezy north winds especially down the Okanogan and Purcell trenches will make for a somewhat raw day. hings are looking up for the end of the week as the trough kicks east into Montana and makes way for a weak but perceptible upper level ridge to build over the region for Friday and Saturday. The polar storm track will remain close by to the north during this period...so while generally dry conditions are expected with warming temperatures (up to about normal by Saturday) at least partly cloudy conditions and a remote threat of some northern mountain showers will prevail. Beyond Saturday models begin to diverge and the moderate to high confidence of the Thursday through Saturday period degrades to low to moderate confidence in the far reaches of the extended forecast. The ECMWF is much more aggressive about building a ridge which implied dry and progressively warmer conditions through the beginning of the next work week...while the GFS maintains a flat and weaker ridge subject to flattening by weak transient disturbances implying significant clouds and a small threat of showers particularly on Sunday night and Monday with continued seasonably normal temperatures. In any event it does appear that models are in agreement that there will be no significant or organized storm systems through early next week...and in this regime it is a safe bet that the basin will remain dry while any threat of showers remains confined to the northern mountains and Cascades. /Fugazzi && .PRELIMINARY POINT TEMPS/POPS... Spokane 59 40 59 42 63 43 / 70 20 20 10 10 10 Coeur d`Alene 56 40 57 41 62 41 / 80 30 30 10 10 10 Pullman 54 39 57 39 62 39 / 100 40 30 20 10 10 Lewiston 59 47 62 48 67 45 / 100 50 40 30 10 10 Colville 62 40 64 40 67 39 / 40 30 20 10 10 10 Sandpoint 53 36 56 36 60 35 / 70 40 30 10 10 10 Kellogg 50 39 54 39 57 39 / 90 50 30 30 20 10 Moses Lake 65 40 67 42 69 43 / 20 20 10 0 0 0 Wenatchee 64 45 66 45 68 47 / 20 20 30 0 0 0 Omak 64 39 67 40 68 42 / 20 20 10 0 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. && $$
AREA FORECAST DISCUSSION
NWS SPOKANE WA
510 AM PDT Tue Sep 24 2013 .SYNOPSIS... An upper level low will be the dominant weather feature through much of the week. this will result in rain showers and mountain snow showers at times through Thursday. Temperatures are expected to remain well below normal. A warming and drying trend is expected by the weekend. && .DISCUSSION... Morning update sent to fine tune Pops and QPF across the forecast area. Steady stream of showers/rain has setup where expected...generally from Pendleton to Pullman/Lewiston to Mullan. Main updates to these areas was to increase QPF amts with some heavier embedded cells producing 0.05" or more per hour. Satellite and radar indicate showers filling across the Spokane- CDA area and even as far northwest as Grand Coulee. Water Vapor and model data confirm a weak shortwave embedded within the SW flow and latest HRRR is handling the current situation. This would suggest showers will continue to fill in across NE WA and Nrn ID this morning impacting most communities from Republic to Bonners Ferry. This activity is more scattered in nature so not every point is a sure bet for rainfall. These showers are moving at a good rate so most precipitation amts will be less then 0.05". One other item of note via the latest HRRR is how convective showers trend after 20z across the entire region. As the trof settles into the region and 500mb cool...isolated showers will be possible for just about every location and we have increased even the lee of the Cascades to slight chance given the lack of a strong rain shadow. This will need to be monitored closely across the far southeast as any sunshine could deliver a few hundred joules of CAPE and potential for isolated storms producing heavy rainfall. /sb && .AVIATION... 12Z TAFS: Wdsprd -shra and -ra will impact southeastern WA and the the ID Panhandle through 00z with the most persistent band of pcpn btwn KPUW and KLWS. MVFR cigs are anticipated under this band. Aft 20z...a cool upper-level trof sags into the region steepening midlevel lapse rates and renewing the threat for showers just about everywhere. A drying trend is expected to commence aft 06z along the immediate Canadian Border and migrate south as drier...northerly winds materialize. /sb && .PREV DISCUSSION... /ISSUED 435 AM PDT Tue Sep 24 2013/ SYNOPSIS... An upper level low will be the dominant weather feature through much of the week. this will result in rain showers and mountain snow showers at times through Thursday. Temperatures are expected to remain well below normal. A warming and drying trend is expected by the weekend. DISCUSSION... Tuesday and Tuesday night: A deep trof of low pressure will carve into the Pac NW bringing a continuation of below normal temperatures and unsettled weather. The most persistent area of precipitation will focus across far southeastern WA and the lower ID Panhandle however showers will be common across all mountains surrounding the deep Basin and expanding at times into the West Plains. As of 2AM...a line of showers has developed from Mullan to Pullman/Lewiston to Pendleton very close to where model guidance indicated over the last 48 hours. Rainfall rates under this band have generally be around 0.01 to 0.04" per hour. Expect this band to sit in place until late Tuesday afternoon/early evening with rainfall amounts spanning from a quarter to half an inch. Locally higher amounts could be possible over the Camas Prairie; especially if a few sun-breaks on Tuesday aftn add a convective element. Further north into the northeastern mountains of WA...Nrn ID Panhandle...and Spokane-CDA area...a combination of afternoon heating...orographics...and especially a shortwave passage during the afternoon will also bring the threat for widely scattered showers. This should be a bit more widespread and wetter then Tuesday given the potential shortwave dynamics and PoPs may need to be further increased for locations like Spokane...Deer Park... Coeur D Alene...Sandpoint...and Bonners Ferry. Will be taking a look at incoming HRRR runs and 12z guidance before deciding. By this evening and overnight...the upper-level trof will become firmly entrenched over the Pac NW. Cooling 500mb temperatures near -25C will promote steepening midlevel lapse rates. A pressure trof at the surface will begin to weaken and sag south and a cool high pressure cell slipping into BC will create northerly gradients across the CWA. This will draw cooler but drier air southward into the CWA leading to a decreasing shower trend and potential for locally gusty winds through the Okanogan Valley. A few of the northern valleys like Republic...Deer Park...and Priest Lake will be close to the freezing mark while most other lowlands dip into the upper 30`s to mid 40`s. /sb Wednesday and Wednesday Night: A closed low continues to pass to the south of our forecast area but will still present some unsettled conditions. Best chances for precipitation look to be Tomorrow Afternoon in the ID Panhandle pushing back west into the Blue Mtns. Rain showers will be the most likely mode of precipitation...but a couple claps of thunder cannot be ruled out with some weak instability in the Panhandle associated with the trof and closed low. Precip amounts look to be pretty limited with this system...but convective enhanced showers could bring moderate showers for localized areas. By Wednesday Night the trof will be pushing to the east limiting the overall chance for precipitation in our forecast area. Winds will be the main factor during this period with gusty conditions expected Wednesday for the Okanogan Valley. Winds from the north will channel down the valley enhancing the winds with gusts in the range of 25 to 30mph. The gusty conditions will continue down into the western Basin with values more in the 20 to 25mph range. The winds will be something to monitor throughout the day for the north-south oriented valleys in north Washington. Temperatures with the northerly flow will be below normal with upper 50s and low 60s for most locations minus the deep basin and lower valleys. Overnight lows will be in the 30s and low 40s for most of the region. Patchy frost was added for Wednesday Night as cold conditions will continue into the overnight hours. Main focus for frost will be the Republic area along with the Priest Lake and Deer Park areas. Fog will also be present in some valley locations. Any areas with fog will likely not see the frost as the fog will prevent strong radiational cooling. Snow levels will remain lower allowing high elevations in the Cascades and ID Panhandle to see some flurries...but no lasting accumulations are expected. /Fliehman Thursday through Monday...Model agreement is good and consistent Thursday through Saturday. The deep trough over the region will move off to the east on Thursday but some lingering shower activity will continue primarily over the Idaho Panhandle and possibly far eastern Washington. Temperatures will continue to run below normal and locally breezy north winds especially down the Okanogan and Purcell trenches will make for a somewhat raw day. hings are looking up for the end of the week as the trough kicks east into Montana and makes way for a weak but perceptible upper level ridge to build over the region for Friday and Saturday. The polar storm track will remain close by to the north during this period...so while generally dry conditions are expected with warming temperatures (up to about normal by Saturday) at least partly cloudy conditions and a remote threat of some northern mountain showers will prevail. Beyond Saturday models begin to diverge and the moderate to high confidence of the Thursday through Saturday period degrades to low to moderate confidence in the far reaches of the extended forecast. The ECMWF is much more aggressive about building a ridge which implied dry and progressively warmer conditions through the beginning of the next work week...while the GFS maintains a flat and weaker ridge subject to flattening by weak transient disturbances implying significant clouds and a small threat of showers particularly on Sunday night and Monday with continued seasonably normal temperatures. In any event it does appear that models are in agreement that there will be no significant or organized storm systems through early next week...and in this regime it is a safe bet that the basin will remain dry while any threat of showers remains confined to the northern mountains and Cascades. /Fugazzi AVIATION... 12Z TAFS: Wdsprd -shra and -ra will impact southeastern WA and the the ID Panhandle through 00z with the most persistent band of pcpn btwn KPUW and KLWS. MVFR cigs are anticipated under this band. Aft 20z...a cool upper-level trof sags into the region steepening midlevel lapse rates and renewing the threat for showers just about everywhere. A drying trend is expected to commence aft 06z along the immediate Canadian Border and migrate south as drier...northerly winds materialize. /sb && .PRELIMINARY POINT TEMPS/POPS... Spokane 59 40 59 42 63 43 / 70 20 20 10 10 10 Coeur d`Alene 56 40 57 41 62 41 / 80 30 30 10 10 10 Pullman 54 39 57 39 62 39 / 100 40 30 20 10 10 Lewiston 59 47 62 48 67 45 / 100 50 40 30 10 10 Colville 62 40 64 40 67 39 / 40 30 20 10 10 10 Sandpoint 53 36 56 36 60 35 / 70 40 30 10 10 10 Kellogg 50 39 54 39 57 39 / 90 50 30 30 20 10 Moses Lake 65 40 67 42 69 43 / 20 20 10 0 0 0 Wenatchee 64 45 66 45 68 47 / 20 20 30 0 0 0 Omak 64 39 67 40 68 42 / 20 20 10 0 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. && $$
AREA FORECAST DISCUSSION
NWS SPOKANE WA
435 AM PDT Tue Sep 24 2013 .SYNOPSIS... An upper level low will be the dominant weather feature through much of the week. this will result in rain showers and mountain snow showers at times through Thursday. Temperatures are expected to remain well below normal. A warming and drying trend is expected by the weekend. && .DISCUSSION... Tuesday and Tuesday night: A deep trof of low pressure will carve into the Pac NW bringing a continuation of below normal temperatures and unsettled weather. The most persistent area of precipitation will focus across far southeastern WA and the lower ID Panhandle however showers will be common across all mountains surrounding the deep Basin and expanding at times into the West Plains. As of 2AM...a line of showers has developed from Mullan to Pullman/Lewiston to Pendleton very close to where model guidance indicated over the last 48 hours. Rainfall rates under this band have generally be around 0.01 to 0.04" per hour. Expect this band to sit in place until late Tuesday afternoon/early evening with rainfall amounts spanning from a quarter to half an inch. Locally higher amounts could be possible over the Camas Prairie; especially if a few sun-breaks on Tuesday aftn add a convective element. Further north into the northeastern mountains of WA...Nrn ID Panhandle...and Spokane-CDA area...a combination of afternoon heating...orographics...and especially a shortwave passage during the afternoon will also bring the threat for widely scattered showers. This should be a bit more widespread and wetter then Tuesday given the potential shortwave dynamics and PoPs may need to be further increased for locations like Spokane...Deer Park... Coeur D Alene...Sandpoint...and Bonners Ferry. Will be taking a look at incoming HRRR runs and 12z guidance before deciding. By this evening and overnight...the upper-level trof will become firmly entrenched over the Pac NW. Cooling 500mb temperatures near -25C will promote steepening midlevel lapse rates. A pressure trof at the surface will begin to weaken and sag south and a cool high pressure cell slipping into BC will create northerly gradients across the CWA. This will draw cooler but drier air southward into the CWA leading to a decreasing shower trend and potential for locally gusty winds through the Okanogan Valley. A few of the northern valleys like Republic...Deer Park...and Priest Lake will be close to the freezing mark while most other lowlands dip into the upper 30`s to mid 40`s. /sb Wednesday and Wednesday Night: A closed low continues to pass to the south of our forecast area but will still present some unsettled conditions. Best chances for precipitation look to be Tomorrow Afternoon in the ID Panhandle pushing back west into the Blue Mtns. Rain showers will be the most likely mode of precipitation...but a couple claps of thunder cannot be ruled out with some weak instability in the Panhandle associated with the trof and closed low. Precip amounts look to be pretty limited with this system...but convective enhanced showers could bring moderate showers for localized areas. By Wednesday Night the trof will be pushing to the east limiting the overall chance for precipitation in our forecast area. Winds will be the main factor during this period with gusty conditions expected Wednesday for the Okanogan Valley. Winds from the north will channel down the valley enhancing the winds with gusts in the range of 25 to 30mph. The gusty conditions will continue down into the western Basin with values more in the 20 to 25mph range. The winds will be something to monitor throughout the day for the north-south oriented valleys in north Washington. Temperatures with the northerly flow will be below normal with upper 50s and low 60s for most locations minus the deep basin and lower valleys. Overnight lows will be in the 30s and low 40s for most of the region. Patchy frost was added for Wednesday Night as cold conditions will continue into the overnight hours. Main focus for frost will be the Republic area along with the Priest Lake and Deer Park areas. Fog will also be present in some valley locations. Any areas with fog will likely not see the frost as the fog will prevent strong radiational cooling. Snow levels will remain lower allowing high elevations in the Cascades and ID Panhandle to see some flurries...but no lasting accumulations are expected. /Fliehman Thursday through Monday...Model agreement is good and consistent Thursday through Saturday. The deep trough over the region will move off to the east on Thursday but some lingering shower activity will continue primarily over the Idaho Panhandle and possibly far eastern Washington. Temperatures will continue to run below normal and locally breezy north winds especially down the Okanogan and Purcell trenches will make for a somewhat raw day. hings are looking up for the end of the week as the trough kicks east into Montana and makes way for a weak but perceptible upper level ridge to build over the region for Friday and Saturday. The polar storm track will remain close by to the north during this period...so while generally dry conditions are expected with warming temperatures (up to about normal by Saturday) at least partly cloudy conditions and a remote threat of some northern mountain showers will prevail. Beyond Saturday models begin to diverge and the moderate to high confidence of the Thursday through Saturday period degrades to low to moderate confidence in the far reaches of the extended forecast. The ECMWF is much more aggressive about building a ridge which implied dry and progressively warmer conditions through the beginning of the next work week...while the GFS maintains a flat and weaker ridge subject to flattening by weak transient disturbances implying significant clouds and a small threat of showers particularly on Sunday night and Monday with continued seasonably normal temperatures. In any event it does appear that models are in agreement that there will be no significant or organized storm systems through early next week...and in this regime it is a safe bet that the basin will remain dry while any threat of showers remains confined to the northern mountains and Cascades. /Fugazzi && .AVIATION... 12Z TAFS: Wdsprd -shra and -ra will impact southeastern WA and the the ID Panhandle through 00z with the most persistent band of pcpn btwn KPUW and KLWS. MVFR cigs are anticipated under this band. Aft 20z...a cool upper-level trof sags into the region steepening midlevel lapse rates and renewing the threat for showers just about everywhere. A drying trend is expected to commence aft 06z along the immediate Canadian Border and migrate south as drier...northerly winds materialize. /sb && .PRELIMINARY POINT TEMPS/POPS... Spokane 59 40 59 42 63 43 / 20 20 20 10 10 10 Coeur d`Alene 56 40 57 41 62 41 / 30 30 30 10 10 10 Pullman 54 39 57 39 62 39 / 70 40 30 20 10 10 Lewiston 59 47 62 48 67 45 / 90 50 40 30 10 10 Colville 62 40 64 40 67 39 / 20 30 20 10 10 10 Sandpoint 53 36 56 36 60 35 / 40 40 30 10 10 10 Kellogg 50 39 54 39 57 39 / 80 50 30 30 20 10 Moses Lake 65 40 67 42 69 43 / 10 20 10 0 0 0 Wenatchee 64 45 66 45 68 47 / 10 20 30 0 0 0 Omak 64 39 67 40 68 42 / 10 20 10 0 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. && $$
AREA FORECAST DISCUSSION
NWS SPOKANE WA
228 AM PDT Tue Sep 24 2013 .SYNOPSIS... An upper level low will be the dominant weather feature through much of the week. this will result in rain showers and mountain snow showers at times through Thursday. Temperatures are expected to remain well below normal. A warming and drying trend is expected by the weekend. && .DISCUSSION... Tuesday and Tuesday night: A deep trof of low pressure will carve into the Pac NW bringing a continuation of below normal temperatures and unsettled weather. The most persistent area of precipitation will focus across far southeastern WA and the lower ID Panhandle however showers will be common across all mountains surrounding the deep Basin and expanding at times into the West Plains. As of 2AM...a line of showers has developed from Mullan to Pullman/Lewiston to Pendleton very close to where model guidance indicated over the last 48 hours. Rainfall rates under this band have generally be around 0.01 to 0.04" per hour. Expect this band to sit in place until late Tuesday afternoon/early evening with rainfall amounts spanning from a quarter to half an inch. Locally higher amounts could be possible over the Camas Prairie; especially if a few sun-breaks on Tuesday aftn add a convective element. Further north into the northeastern mountains of WA...Nrn ID Panhandle...and Spokane-CDA area...a combination of afternoon heating...orographics...and especially a shortwave passage during the afternoon will also bring the threat for widely scattered showers. This should be a bit more widespread and wetter then Tuesday given the potential shortwave dynamics and PoPs may need to be further increased for locations like Spokane...Deer Park... Coeur D Alene...Sandpoint...and Bonners Ferry. Will be taking a look at incoming HRRR runs and 12z guidance before deciding. By this evening and overnight...the upper-level trof will become firmly entrenched over the Pac NW. Cooling 500mb temperatures near -25C will promote steepening midlevel lapse rates. A pressure trof at the surface will begin to weaken and sag south and a cool high pressure cell slipping into BC will create northerly gradients across the CWA. This will draw cooler but drier air southward into the CWA leading to a decreasing shower trend and potential for locally gusty winds through the Okanogan Valley. A few of the northern valleys like Republic...Deer Park...and Priest Lake will be close to the freezing mark while most other lowlands dip into the upper 30`s to mid 40`s. /sb Wednesday and Wednesday Night: A closed low continues to pass to the south of our forecast area but will still present some unsettled conditions. Best chances for precipitation look to be Tomorrow Afternoon in the ID Panhandle pushing back west into the Blue Mtns. Rain showers will be the most likely mode of precipitation...but a couple claps of thunder cannot be ruled out with some weak instability in the Panhandle associated with the trof and closed low. Precip amounts look to be pretty limited with this system...but convective enhanced showers could bring moderate showers for localized areas. By Wednesday Night the trof will be pushing to the east limiting the overall chance for precipitation in our forecast area. Winds will be the main factor during this period with gusty conditions expected Wednesday for the Okanogan Valley. Winds from the north will channel down the valley enhancing the winds with gusts in the range of 25 to 30mph. The gusty conditions will continue down into the western Basin with values more in the 20 to 25mph range. The winds will be something to monitor throughout the day for the north-south oriented valleys in north Washington. Temperatures with the northerly flow will be below normal with upper 50s and low 60s for most locations minus the deep basin and lower valleys. Overnight lows will be in the 30s and low 40s for most of the region. Patchy frost was added for Wednesday Night as cold conditions will continue into the overnight hours. Main focus for frost will be the Republic area along with the Priest Lake and Deer Park areas. Fog will also be present in some valley locations. Any areas with fog will likely not see the frost as the fog will prevent strong radiational cooling. Snow levels will remain lower allowing high elevations in the Cascades and ID Panhandle to see some flurries...but no lasting accumulations are expected. /Fliehman Thursday through Monday...Model agreement is good and consistent Thursday through Saturday. The deep trough over the region will move off to the east on Thursday but some lingering shower activity will continue primarily over the Idaho Panhandle and possibly far eastern Washington. Temperatures will continue to run below normal and locally breezy north winds especially down the Okanogan and Purcell trenches will make for a somewhat raw day. hings are looking up for the end of the week as the trough kicks east into Montana and makes way for a weak but perceptible upper level ridge to build over the region for Friday and Saturday. The polar storm track will remain close by to the north during this period...so while generally dry conditions are expected with warming temperatures (up to about normal by Saturday) at least partly cloudy conditions and a remote threat of some northern mountain showers will prevail. Beyond Saturday models begin to diverge and the moderate to high confidence of the Thursday through Saturday period degrades to low to moderate confidence in the far reaches of the extended forecast. The ECMWF is much more aggressive about building a ridge which implied dry and progressively warmer conditions through the beginning of the next work week...while the GFS maintains a flat and weaker ridge subject to flattening by weak transient disturbances implying significant clouds and a small threat of showers particularly on Sunday night and Monday with continued seasonably normal temperatures. In any event it does appear that models are in agreement that there will be no significant or organized storm systems through early next week...and in this regime it is a safe bet that the basin will remain dry while any threat of showers remains confined to the northern mountains and Cascades. /Fugazzi && .AVIATION... 06Z TAFS: VFR through this evening for most locations as spotty shower activity subsides, however to the southeast a frontal zone forms and intensifies near Blue Mountains and over KLWS and KPUW and up to Shoshone County in North Idaho. This frontal zone will straighten enough and move little with time so as to keep rain and associated ceilings down to MVFR in that same area after 12Z and on through 00Z Wednesday until it moves away to the east near 06Z Wednesday. /Pelatti && .PRELIMINARY POINT TEMPS/POPS... Spokane 59 40 59 42 63 43 / 20 20 20 10 10 10 Coeur d`Alene 56 40 57 41 62 41 / 30 30 30 10 10 10 Pullman 54 39 57 39 62 39 / 70 40 30 20 10 10 Lewiston 59 47 62 48 67 45 / 90 50 40 30 10 10 Colville 62 40 64 40 67 39 / 20 30 20 10 10 10 Sandpoint 53 36 56 36 60 35 / 40 40 30 10 10 10 Kellogg 50 39 54 39 57 39 / 80 50 30 30 20 10 Moses Lake 65 40 67 42 69 43 / 10 20 10 0 0 0 Wenatchee 64 45 66 45 68 47 / 10 20 30 0 0 0 Omak 64 39 67 40 68 42 / 10 20 10 0 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. && $$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
959 PM CDT WED SEP 25 2013 UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE .UPDATE... ISSUED AT 911 PM CDT WED SEP 25 2013 AFTER DISCUSSING THE SITN WITH ADJACENT OFFICES...WL HOLD OFF ON THE DENSE FOG ADVISORY. 00Z NAM FCSTG BOUNDARY LAYER WINDS TO INCR A LITTLE DURING THE NGT. HOPEFULLY THAT WL PREVENT THE DENSE FG FROM BECOMING AS WIDESPREAD AS THE LAST COUPLE NGTS. UPDATE ISSUED AT 841 PM CDT WED SEP 25 2013 ANOTHER NIGHT OF TRYING TO FIGURE OUT HOW MUCH FOG WILL FORM. LOOKS LIKE THE SFC PRESSURE GRADIENT WL TIGHTEN JUST A LITTLE OVERNIGHT...AND BOUNDARY LAYER WINDS MAY PICK OF A TOUCH ALSO. BUT SIMILAR CONDITIONS 2 NIGHTS AGO DIDN/T PREVENT THE FOG FROM FORMING. WL AWAIT THE 02Z OBS AND MAKE A FINAL DECISION ON WHETHER OR NOT TO POST A DENSE FOG ADVISORY. THOUGHT RIGHT NOW IS THAT IF ONE IS NEEDED...ITS GOING TO BE FOR N-C WI. THE DENSE FOG PROBABLY WON/T BE WIDESPREAD ENOUGH TO JUSTIFY ONE ELSEWHERE. && .SHORT TERM...TONIGHT AND THURSDAY ISSUED AT 249 PM CDT WED SEP 25 2013 LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW SURFACE HIGH PRESSURE STRETCHING FROM THE WESTERN GULF OF MEXICO TO THE WESTERN GREAT LAKES AND THEN ONTO QUEBEC. MOST OF THE FOG BURNED OFF BETWEEN 15-16Z THIS MORNING...AND THEN TRANSFORMED INTO A BKN CU FIELD OVER CENTRAL AND NORTHEAST WISCONSIN. TEMPERATURES ARE LAGGING BEHIND A LITTLE BIT AND RESIDE IN THE MIDDLE TO UPPER 60S. WITH SYNOPTIC CONDITIONS CHANGING LITTLE OVER THE NEXT 24 HOURS...FOG POTENTIAL WILL REMAIN THE MAIN FORECAST CONCERN IN THE SHORT TERM. TONIGHT...MID-LEVEL RIDGE AXIS WILL BUILD NORTHEAST ACROSS THE WESTERN GREAT LAKES WHILE HIGH PRESSURE REMAINS CENTERED OVER EASTERN ONTARIO AND WESTERN QUEBEC. THE AIRMASS WILL REMAIN VIRTUALLY UNCHANGED FROM LAST NIGHT...WITH PWATS AROUND 0.40 INCHES...AND A LIGHT EASTERLY COMPONENT IN THE LOW LEVELS WHICH WILL KEEP A STEADY SUPPLY OF MOISTURE. THE PRESSURE GRADIENT WILL BECOME TIGHTER OVER WESTERN AND CENTRAL WISCONSIN...AND BL WINDS ARE MORE MARGINAL IN THESE LOCATIONS FOR WIDESPREAD DENSE FOG. BUT DO NOT THINK THE GRADIENT WILL BE TIGHT ENOUGH TO PREVENT DENSE FOG FROM FORMING OVER THE HIGHER TERRAIN OF N-C WISCONSIN. OVER NORTHEAST AND EAST-CENTRAL WISCONSIN...SURFACE WINDS SHOULD BE CALM FOR MUCH OF THE NIGHT...AND EXPECT A REPEAT PERFORMANCE OF FOG AND LOW STRATUS. FOG HEADLINES LOOK POSSIBLE ONCE AGAIN AND WILL GO WITH AREAS OF FOG/LOCALLY DENSE WORDING. LOWS A COUPLE DEGREES WARMER THAN LAST NIGHT...IN THE UPPER 30S TO MID 40S. THURSDAY...AREAS OF FOG...LOCALLY DENSE...WILL CONTINUE TO BE PRESENT THROUGH 14-15Z. THEREAFTER...SHOULD SEE THE FOG TURN INTO A CU FIELD...WHICH WILL BURN OFF MID TO LATE AFTERNOON. HIGHS WILL BE SEVERAL DEGREES WARMER THAN TODAY AND WILL GO WITH LOW TO MID 70S. .LONG TERM...THURSDAY NIGHT THROUGH WEDNESDAY ISSUED AT 249 PM CDT WED SEP 25 2013 FORECAST CONCERNS THIS PERIOD ON PCPN CHANCES THIS WEEKEND AS HIGH PRESSURE GIVES WAY TO A COLD FRONT AND UPPER TROUGH THIS WEEKEND. CHALLENGE LAST FEW DAYS HAS BEEN WITH TIMING. AS WITH LAST NIGHT...MODELS TENDING TO SPEED THINGS UP WITH BOTH NCEP MODELS BRINGING FRONT INTO EASTERN WI LATE SAT AFTERNOON. GEM/ECMWF ARE STILL SLOWER. STILL EXPECT SOME TIMING GYRATIONS, AS PIECE OF ENERGY THAT WILL ORCHESTRATE THE LIFTING OUT OF THE UPPER TROF INTO THE NORTHERN PLAINS, JUST ROUNDING THE BACK SIDE OF UPPER LOW OVER PAC NW. MODELS CONSISTENT WITH MAIN DYNAMICS WITH TROF TO PASS NORTH AND WEST OF CWA...THOUGH GOOD AVAILABLE MOISTURE /PWS AROUND 1.5/ AND CONVERGENCE ALONG COLD FRONT ENOUGH TO BRING/KEEP POPS INTO LIKELY CATEGORY. FLOW TO BECOME MORE ZONAL SUN ONWARD WITH MILD PACIFIC PATTERN EXPECTED AS WESTERLIES LIE ALONG NORTHERN TIER OF U.S. EXTENDED PERIODS DOTTED WITH SMALL POPS DUE TO TIMING ISSUES WITH FASTER ZONAL FLOW. && .AVIATION...FOR 06Z TAF ISSUANCE ISSUED AT 957 PM CDT WED SEP 25 2013 FOG WL BE AN ISSUE AGAIN TNGT. BASIC WX PATTERN VERY SIMILAR TO LAST NGT...THOUGH PERHAPS BOUNDARY LAYER WINDS WL BE A LITTLE STRONGER AND KEEP THINGS STIRRED UP A LITTLE MORE. WL CONT TO LEAN TOWARD PERSISTENCE FOR THE TIMING/EXTENT OF THE FG IN THE TAFS. && .MARINE... ISSUED AT 249 PM CDT WED SEP 25 2013 EXTENDED PERIOD OF SOUTHERLY WINDS FRI NIGHT AND SAT TO BUILD WAVES OVER LAKE MICHIGAN WITH SMALL CRAFT CONDITIONS EXPECTED. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE.........SKOWRONSKI SHORT TERM.....MPC LONG TERM......TE AVIATION.......SKOWRONSKI MARINE.........TE
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
931 PM CDT WED SEP 25 2013 .UPDATE... VISIBILITIES ARE BEGINNING TO DROP AT FAVORED LOCATIONS IN THE NORTHERN KETTLE MORAINE AND EXPECT AREAS OF FOG AGAIN OVERNIGHT INTO EARLY THURSDAY MORNING. FULLY EXPECT THERE WILL BE A FOG ADVISORY IN PLACE BEFORE THE MORNING COMMUTE...BUT THE QUESTION REMAINS EXACTLY WHERE AND TO WHAT AREAL EXTENT. LATEST NAM VSBY FORECAST PUTS MOST OF SOUTHEAST WISCONSIN UNDER 1/4 MILE AFTER 09Z...SIMILAR TO HRRR AND SIMILAR TO WHAT BOTH DID LAST NIGHT. BUT SREF PROBABILITIES OF VSBY LESS THAN 1 MILE ONLY RISE TO AROUND 40 PCT IN TWO POCKETS OVER MARQUETTE COUNTY AND JEFFERSON COUNTY. WILL EXPAND AREAS OF FOG WITH PATCHY DENSE FARTHER SOUTH TO COVER ALL OF THE SOUTHEAST EXCEPT NEAR THE LAKE. SOUTHWEST SECTIONS OF THE CWA LOOK TO REMAIN SOMEWHAT MIXED WITH A BIT MORE GRADIENT WIND OVERNIGHT...EXCEPT FOR THE WI RIVER VALLEY...SO WILL LEAVE PATCHY WORDING THERE FOR NOW. WILL KEEP A CLOSE EYE ON TRENDS FOR ADVISORY ISSUANCE ON THIS SHIFT. && .AVIATION/06Z TAFS/... EXPECT MVFR FOG AT ALL TAF SITES BY 06Z EXCEPT KMKE...WITH IFR AT KMSN AND KENW OVERNIGHT INTO THE EARLY MORNING. VSBYS SHOULD BE AT VFR LEVELS BY 15Z...WITH VFR THROUGH THE REMAINDER OF THE DAYTIME HOURS. EXPECT BETTER SURFACE PRESSURE GRADIENT SHOULD KEEP WINDS UP ENOUGH UNTIL 06Z FRIDAY TO PREVENT ANY FOG DEVELOPMENT THURSDAY EVENING. && .PREV DISCUSSION... /ISSUED 320 PM CDT WED SEP 25 2013/ VERY SHORT TERM...TONIGHT AND THURSDAY. SHORT TERM MODELS IN GOOD AGREEMENT WITH HIGH PRESSURE REMAINING NORTHEAST OF THE REGION DURING THIS TIME. THIS WILL CONTINUE THE QUIET WEATHER ACROSS THE AREA. PERSISTENCE TYPE OF FORECAST SEEMS REASONABLE ONCE AGAIN. THUS...SOME DIURNAL CUMULUS CLOUDS ARE POSSIBLE IN THE EAST LATE THURSDAY MORNING INTO THE AFTERNOON. TEMPERATURES TONIGHT WILL DROP INTO THE LOWER TO MID 40S INLAND...WITH MILDER VALUES NEAR THE LAKE PER 925MB TEMPERATURE FIELDS. HIGHS THURSDAY SHOULD TOP OUT IN THE MID TO UPPER 70S WELL INLAND...SOMEWHAT COOLER WITH ONSHORE WINDS NEAR THE LAKE. MAIN ISSUE IN THIS PERIOD WILL BE HOW MUCH FOG FORMS AGAIN LATER TONIGHT INTO EARLY THURSDAY MORNING. WINDS WILL DECOUPLE AGAIN DURING THIS TIME...THOUGH BOUNDARY LAYER WINDS SHOULD BE A BIT STRONGER THAN LAST NIGHT. STILL...FAIRLY SIMILAR SETUP TO LAST NIGHT. THUS...ADDED AREAS OF FOG WITH PATCHY DENSE FOG TO NORTH HALF OF AREA...PLUS AREAS IN THE SOUTH THAT HAD THE DENSE FOG EARLIER THIS MORNING. LATER SHIFTS WILL AGAIN NEED TO MONITOR FOR A DENSE FOG ADVISORY LATER TONIGHT INTO EARLY THURSDAY MORNING. SHORT TERM...THURSDAY NIGHT THROUGH SATURDAY. DRY SOUTHEASTERLY FLOW AND SUBSIDENCE ASSOCIATED WITH HIGH PRESSURE WILL CONTINUE TO BRING QUIET AND COMFORTABLE WEATHER THROUGH FRIDAY NIGHT. A BIT MORE BOUNDARY LAYER MIXING THURSDAY NIGHT AND FRIDAY NIGHT SHOULD PREVENT SIGNIFICANT DENSE FOG. LATEST SHORT TERM GUIDANCE INCLUDING ECMWF SHOWING MORE PROGRESSIVE WESTERLY FLOW IN THE MID-LEVELS ON SATURDAY DUE TO LESS UPSTREAM RIDGING OVER THE NORTHERN PLAINS. HENCE SFC COLD FRONT EXPECTED TO MOVE EWD A LITTLE FASTER ON SATURDAY AND SATURDAY NIGHT. COLUMN PWAT VALUES INCREASE RAPIDLY TO OVER ONE INCH ON SATURDAY ALONG AND AHEAD OF THE APPROACHING COLD FRONT. AXIS OF Q-VECTOR CONVERGENCE AND MID-LEVEL FRONTOGENETICAL FORCING SWEEP ACROSS WESTERN CWA LATER ON SATURDAY...AND WEAKEN AS THE FORCING PROGRESSES EWD SATURDAY EVENING. BUMPED UP POPS TO LIKELY OVER WESTERN CWA SATURDAY AFTN...AND LEFT LIKELY IN THE EVENING IN THE EAST. TRIMMED POPS BACK LATER IN THE NIGHT...AND CONSIDERING SPEED OF THIS BOUNDARY...FUTURE SHIFTS MAY NEED TO FURTHER TRIM POPS BACK FOR THE LATE NIGHT. LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY. WILL CARRY HIGHEST POPS FOR THE PERIOD SATURDAY NIGHT IN THE EAST AS SFC CDFNT MOVES THROUGH SRN WI. WL CONTINUE SCENARIO OF DRY WEATHER RETURNING ON SUNDAY AS CDFNT SHOULD BE FAR ENOUGH EAST OF AREA. FAST WESTERLIES WILL CARRY WEAK SURFACE OCCLUSION ASSOCIATED WITH STRONG LOW PRESSURE MOVING THROUGH SOUTHERN/CENTRAL CANADA ACROSS WESTERN GTLAKES TUE NIGHT/WED. SOME DIFFERENCES IN TIMING OF PASSING BOUNDARY BETWEEN ECMWF AND GFS. FOR NOW WL CONTINUE SMALL POPS DURING THIS PERIOD. TEMPERATURES WILL REMAIN NEAR OR ABV SEASONAL NORMAL THROUGH THE PERIOD...WITH LITTLE THREAT OF FREEZING TEMPS AND FROST. PORTIONS OF SOUTHERN WI NOW REACHING THE AVERAGE DATE OF FIRST OCCURRENCE OF 32F OR LOWER. AVIATION /00Z TAFS/... HIGH PRESSURE WILL REMAIN NORTHEAST OF THE REGION THROUGH THURSDAY. MVFR/VFR DIURNAL CUMULUS CLOUDS ARE EXPECTED TO GRADUALLY DIMINISH BY SUNSET. LIGHT EAST WINDS ARE EXPECTED AS WELL. LIGHT/CALM WINDS ARE EXPECTED TONIGHT INTO EARLY THURSDAY MORNING. ANOTHER ROUND OF MVFR/IFR FOG IS EXPECTED AT TAF SITES EXCEPT MILWAUKEE DURING THIS TIME. MAIN PERIOD WILL BE BETWEEN 05Z AND 13Z THURSDAY. VISIBILITIES DOWN TO AND BELOW ALTERNATE MINIMUMS ARE EXPECTED. MAY SEE PATCHY DENSE FOG AS WELL...BUT NOT WIDESPREAD ENOUGH TO MENTION IN TAFS FOR NOW. LIGHT TO MODERATE SOUTHEAST WINDS ARE EXPECTED LATER THURSDAY MORNING AND AFTERNOON...WITH MORE MVFR/VFR DIURNAL CUMULUS POSSIBLE AT THE EASTERN SITES. MARINE...WINDS AND WAVES MAY REACH SMALL CRAFT ADVISORY LEVELS MAINLY ON SATURDAY ACROSS THE NEARSHORE WATERS OF LAKE MICHIGAN. A TIGHT PRESSURE GRADIENT AHEAD OF A COLD FRONT SHOULD BRING GUSTY SOUTH/SOUTHEAST WINDS UP TO 25 KNOTS DURING THIS TIME. THESE WINDS SHOULD GENERATE HIGH WAVES OF 3 TO 6 FEET. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...NONE. && $$ UPDATE...REM TONIGHT/THURSDAY AND AVIATION/MARINE...WOOD THURSDAY NIGHT THROUGH WEDNESDAY...MBK
AREA FORECAST DISCUSSION...UPDATED
NWS GREEN BAY WI
915 PM CDT WED SEP 25 2013 NEW INFORMATION ADDED TO UPDATE SECTION .UPDATE... ISSUED AT 911 PM CDT WED SEP 25 2013 AFTER DISCUSSING THE SITN WITH ADJACENT OFFICES...WL HOLD OFF ON THE DENSE FOG ADVISORY. 00Z NAM FCSTG BOUNDARY LAYER WINDS TO INCR A LITTLE DURING THE NGT. HOPEFULLY THAT WL PREVENT THE DENSE FG FROM BECOMING AS WIDESPREAD AS THE LAST COUPLE NGTS. UPDATE ISSUED AT 841 PM CDT WED SEP 25 2013 ANOTHER NIGHT OF TRYING TO FIGURE OUT HOW MUCH FOG WILL FORM. LOOKS LIKE THE SFC PRESSURE GRADIENT WL TIGHTEN JUST A LITTLE OVERNIGHT...AND BOUNDARY LAYER WINDS MAY PICK OF A TOUCH ALSO. BUT SIMILAR CONDITIONS 2 NIGHTS AGO DIDN/T PREVENT THE FOG FROM FORMING. WL AWAIT THE 02Z OBS AND MAKE A FINAL DECISION ON WHETHER OR NOT TO POST A DENSE FOG ADVISORY. THOUGHT RIGHT NOW IS THAT IF ONE IS NEEDED...ITS GOING TO BE FOR N-C WI. THE DENSE FOG PROBABLY WON/T BE WIDESPREAD ENOUGH TO JUSTIFY ONE ELSEWHERE. && .SHORT TERM...TONIGHT AND THURSDAY ISSUED AT 249 PM CDT WED SEP 25 2013 LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW SURFACE HIGH PRESSURE STRETCHING FROM THE WESTERN GULF OF MEXICO TO THE WESTERN GREAT LAKES AND THEN ONTO QUEBEC. MOST OF THE FOG BURNED OFF BETWEEN 15-16Z THIS MORNING...AND THEN TRANSFORMED INTO A BKN CU FIELD OVER CENTRAL AND NORTHEAST WISCONSIN. TEMPERATURES ARE LAGGING BEHIND A LITTLE BIT AND RESIDE IN THE MIDDLE TO UPPER 60S. WITH SYNOPTIC CONDITIONS CHANGING LITTLE OVER THE NEXT 24 HOURS...FOG POTENTIAL WILL REMAIN THE MAIN FORECAST CONCERN IN THE SHORT TERM. TONIGHT...MID-LEVEL RIDGE AXIS WILL BUILD NORTHEAST ACROSS THE WESTERN GREAT LAKES WHILE HIGH PRESSURE REMAINS CENTERED OVER EASTERN ONTARIO AND WESTERN QUEBEC. THE AIRMASS WILL REMAIN VIRTUALLY UNCHANGED FROM LAST NIGHT...WITH PWATS AROUND 0.40 INCHES...AND A LIGHT EASTERLY COMPONENT IN THE LOW LEVELS WHICH WILL KEEP A STEADY SUPPLY OF MOISTURE. THE PRESSURE GRADIENT WILL BECOME TIGHTER OVER WESTERN AND CENTRAL WISCONSIN...AND BL WINDS ARE MORE MARGINAL IN THESE LOCATIONS FOR WIDESPREAD DENSE FOG. BUT DO NOT THINK THE GRADIENT WILL BE TIGHT ENOUGH TO PREVENT DENSE FOG FROM FORMING OVER THE HIGHER TERRAIN OF N-C WISCONSIN. OVER NORTHEAST AND EAST-CENTRAL WISCONSIN...SURFACE WINDS SHOULD BE CALM FOR MUCH OF THE NIGHT...AND EXPECT A REPEAT PERFORMANCE OF FOG AND LOW STRATUS. FOG HEADLINES LOOK POSSIBLE ONCE AGAIN AND WILL GO WITH AREAS OF FOG/LOCALLY DENSE WORDING. LOWS A COUPLE DEGREES WARMER THAN LAST NIGHT...IN THE UPPER 30S TO MID 40S. THURSDAY...AREAS OF FOG...LOCALLY DENSE...WILL CONTINUE TO BE PRESENT THROUGH 14-15Z. THEREAFTER...SHOULD SEE THE FOG TURN INTO A CU FIELD...WHICH WILL BURN OFF MID TO LATE AFTERNOON. HIGHS WILL BE SEVERAL DEGREES WARMER THAN TODAY AND WILL GO WITH LOW TO MID 70S. .LONG TERM...THURSDAY NIGHT THROUGH WEDNESDAY ISSUED AT 249 PM CDT WED SEP 25 2013 FORECAST CONCERNS THIS PERIOD ON PCPN CHANCES THIS WEEKEND AS HIGH PRESSURE GIVES WAY TO A COLD FRONT AND UPPER TROUGH THIS WEEKEND. CHALLENGE LAST FEW DAYS HAS BEEN WITH TIMING. AS WITH LAST NIGHT...MODELS TENDING TO SPEED THINGS UP WITH BOTH NCEP MODELS BRINGING FRONT INTO EASTERN WI LATE SAT AFTERNOON. GEM/ECMWF ARE STILL SLOWER. STILL EXPECT SOME TIMING GYRATIONS, AS PIECE OF ENERGY THAT WILL ORCHESTRATE THE LIFTING OUT OF THE UPPER TROF INTO THE NORTHERN PLAINS, JUST ROUNDING THE BACK SIDE OF UPPER LOW OVER PAC NW. MODELS CONSISTENT WITH MAIN DYNAMICS WITH TROF TO PASS NORTH AND WEST OF CWA...THOUGH GOOD AVAILABLE MOISTURE /PWS AROUND 1.5/ AND CONVERGENCE ALONG COLD FRONT ENOUGH TO BRING/KEEP POPS INTO LIKELY CATEGORY. FLOW TO BECOME MORE ZONAL SUN ONWARD WITH MILD PACIFIC PATTERN EXPECTED AS WESTERLIES LIE ALONG NORTHERN TIER OF U.S. EXTENDED PERIODS DOTTED WITH SMALL POPS DUE TO TIMING ISSUES WITH FASTER ZONAL FLOW. && .AVIATION...FOR 00Z TAF ISSUANCE ISSUED AT 523 PM CDT WED SEP 25 2013 FOG WL BE AN ISSUE AGAIN TNGT. BASIC WX PATTERN VERY SIMILAR TO LAST NGT...SO WL RELY HEAVILY ON PERSISTENCE FOR THE TIMING/EXTENT OF THE FG IN THE TAFS. ONE SIG DIFF IS GRB/S DWPT IS SEVERAL DEGREES HIGHER THAN YDA AT THIS TIME...PROBABLY DUE TO LGT NELY FLOW DOWN THE BAY. THAT MAY ALLOW FOG TO GET GOING HERE A LITTLE EARLIER. && .MARINE... ISSUED AT 249 PM CDT WED SEP 25 2013 EXTENDED PERIOD OF SOUTHERLY WINDS FRI NIGHT AND SAT TO BUILD WAVES OVER LAKE MICHIGAN WITH SMALL CRAFT CONDITIONS EXPECTED. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE.........SKOWRONSKI SHORT TERM.....MPC LONG TERM......TE AVIATION.......SKOWRONSKI MARINE.........TE
AREA FORECAST DISCUSSION...UPDATED
NWS GREEN BAY WI
846 PM CDT WED SEP 25 2013 NEW INFORMATION ADDED TO UPDATE SECTION .UPDATE... ISSUED AT 841 PM CDT WED SEP 25 2013 ANOTHER NIGHT OF TRYING TO FIGURE OUT HOW MUCH FOG WILL FORM. LOOKS LIKE THE SFC PRESSURE GRADIENT WL TIGHTEN JUST A LITTLE OVERNIGHT...AND BOUNDARY LAYER WINDS MAY PICK OF A TOUCH ALSO. BUT SIMILAR CONDITIONS 2 NIGHTS AGO DIDN/T PREVENT THE FOG FROM FORMING. WL AWAIT THE 02Z OBS AND MAKE A FINAL DECISION ON WHETHER OR NOT TO POST A DENSE FOG ADVISORY. THOUGHT RIGHT NOW IS THAT IF ONE IS NEEDED...ITS GOING TO BE FOR N-C WI. THE DENSE FOG PROBABLY WON/T BE WIDESPREAD ENOUGH TO JUSTIFY ONE ELSEWHERE. && .SHORT TERM...TONIGHT AND THURSDAY ISSUED AT 249 PM CDT WED SEP 25 2013 LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW SURFACE HIGH PRESSURE STRETCHING FROM THE WESTERN GULF OF MEXICO TO THE WESTERN GREAT LAKES AND THEN ONTO QUEBEC. MOST OF THE FOG BURNED OFF BETWEEN 15-16Z THIS MORNING...AND THEN TRANSFORMED INTO A BKN CU FIELD OVER CENTRAL AND NORTHEAST WISCONSIN. TEMPERATURES ARE LAGGING BEHIND A LITTLE BIT AND RESIDE IN THE MIDDLE TO UPPER 60S. WITH SYNOPTIC CONDITIONS CHANGING LITTLE OVER THE NEXT 24 HOURS...FOG POTENTIAL WILL REMAIN THE MAIN FORECAST CONCERN IN THE SHORT TERM. TONIGHT...MID-LEVEL RIDGE AXIS WILL BUILD NORTHEAST ACROSS THE WESTERN GREAT LAKES WHILE HIGH PRESSURE REMAINS CENTERED OVER EASTERN ONTARIO AND WESTERN QUEBEC. THE AIRMASS WILL REMAIN VIRTUALLY UNCHANGED FROM LAST NIGHT...WITH PWATS AROUND 0.40 INCHES...AND A LIGHT EASTERLY COMPONENT IN THE LOW LEVELS WHICH WILL KEEP A STEADY SUPPLY OF MOISTURE. THE PRESSURE GRADIENT WILL BECOME TIGHTER OVER WESTERN AND CENTRAL WISCONSIN...AND BL WINDS ARE MORE MARGINAL IN THESE LOCATIONS FOR WIDESPREAD DENSE FOG. BUT DO NOT THINK THE GRADIENT WILL BE TIGHT ENOUGH TO PREVENT DENSE FOG FROM FORMING OVER THE HIGHER TERRAIN OF N-C WISCONSIN. OVER NORTHEAST AND EAST-CENTRAL WISCONSIN...SURFACE WINDS SHOULD BE CALM FOR MUCH OF THE NIGHT...AND EXPECT A REPEAT PERFORMANCE OF FOG AND LOW STRATUS. FOG HEADLINES LOOK POSSIBLE ONCE AGAIN AND WILL GO WITH AREAS OF FOG/LOCALLY DENSE WORDING. LOWS A COUPLE DEGREES WARMER THAN LAST NIGHT...IN THE UPPER 30S TO MID 40S. THURSDAY...AREAS OF FOG...LOCALLY DENSE...WILL CONTINUE TO BE PRESENT THROUGH 14-15Z. THEREAFTER...SHOULD SEE THE FOG TURN INTO A CU FIELD...WHICH WILL BURN OFF MID TO LATE AFTERNOON. HIGHS WILL BE SEVERAL DEGREES WARMER THAN TODAY AND WILL GO WITH LOW TO MID 70S. .LONG TERM...THURSDAY NIGHT THROUGH WEDNESDAY ISSUED AT 249 PM CDT WED SEP 25 2013 FORECAST CONCERNS THIS PERIOD ON PCPN CHANCES THIS WEEKEND AS HIGH PRESSURE GIVES WAY TO A COLD FRONT AND UPPER TROUGH THIS WEEKEND. CHALLENGE LAST FEW DAYS HAS BEEN WITH TIMING. AS WITH LAST NIGHT...MODELS TENDING TO SPEED THINGS UP WITH BOTH NCEP MODELS BRINGING FRONT INTO EASTERN WI LATE SAT AFTERNOON. GEM/ECMWF ARE STILL SLOWER. STILL EXPECT SOME TIMING GYRATIONS, AS PIECE OF ENERGY THAT WILL ORCHESTRATE THE LIFTING OUT OF THE UPPER TROF INTO THE NORTHERN PLAINS, JUST ROUNDING THE BACK SIDE OF UPPER LOW OVER PAC NW. MODELS CONSISTENT WITH MAIN DYNAMICS WITH TROF TO PASS NORTH AND WEST OF CWA...THOUGH GOOD AVAILABLE MOISTURE /PWS AROUND 1.5/ AND CONVERGENCE ALONG COLD FRONT ENOUGH TO BRING/KEEP POPS INTO LIKELY CATEGORY. FLOW TO BECOME MORE ZONAL SUN ONWARD WITH MILD PACIFIC PATTERN EXPECTED AS WESTERLIES LIE ALONG NORTHERN TIER OF U.S. EXTENDED PERIODS DOTTED WITH SMALL POPS DUE TO TIMING ISSUES WITH FASTER ZONAL FLOW. && .AVIATION...FOR 00Z TAF ISSUANCE ISSUED AT 523 PM CDT WED SEP 25 2013 FOG WL BE AN ISSUE AGAIN TNGT. BASIC WX PATTERN VERY SIMILAR TO LAST NGT...SO WL RELY HEAVILY ON PERSISTENCE FOR THE TIMING/EXTENT OF THE FG IN THE TAFS. ONE SIG DIFF IS GRB/S DWPT IS SEVERAL DEGREES HIGHER THAN YDA AT THIS TIME...PROBABLY DUE TO LGT NELY FLOW DOWN THE BAY. THAT MAY ALLOW FOG TO GET GOING HERE A LITTLE EARLIER. && .MARINE... ISSUED AT 249 PM CDT WED SEP 25 2013 EXTENDED PERIOD OF SOUTHERLY WINDS FRI NIGHT AND SAT TO BUILD WAVES OVER LAKE MICHIGAN WITH SMALL CRAFT CONDITIONS EXPECTED. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE.........SKOWRONSKI SHORT TERM.....MPC LONG TERM......TE AVIATION.......SKOWRONSKI MARINE.........TE
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
256 PM CDT TUE SEP 24 2013 .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 256 CDT TUE SEP 24 2013 MINIMAL WEATHER IMPACTS FOR THE AREA UNTIL THE PASSAGE OF COLD FRONT THIS WEEKEND. FOR THIS AFTERNOON...WATER VAPOR IMAGERY OVERLAID WITH RAP 500 MB HEIGHTS CONTINUES TO SHOW DECAYING UPPER LEVEL SHORTWAVE TROUGH ACROSS IOWA...WHICH HAS SPREAD MID/HIGH LEVEL CLOUDS ACROSS NORTHEAST IOWA INTO SOUTHEAST MINNESOTA. A DOWNSTREAM UPPER LEVEL RIDGE IS HOLDING STRONG...HELPING TO KEEP THE DRY AIR MASS IN PLACE...AS SEEN BY THE 24.12Z MPX/GRB SOUNDINGS. FOR TONIGHT...THE SURFACE HIGH PRESSURE REMAINS TO OUR EAST AND OVERALL THE SURFACE PRESSURE FIELDS ARE VERY BAGGY. FORECAST SOUNDINGS INDICATE THAT THROUGH AROUND 400 MB THE WIND FIELD IS LESS THAN 10 KTS. AS WAS THE CASE THIS MORNING...EXPECTING PATCHY DENSE FOG TO DEVELOP ACROSS LOW LYING AREAS OF CENTRAL WISCONSIN...AND POSSIBLY IN THE MS AND WISCONSIN RIVER VALLEYS. THE MORE FAVORABLE SET UP EXISTS ACROSS CENTRAL WISCONSIN BUT COULD NOT RULE PATCHY FOG ACROSS SOUTHEAST MINNESOTA AND NORTHEAST IOWA DURING THE EARLY MORNING HOURS. OVERALL..THE MAIN LIMITING FACTOR FOR A MORE WIDESPREAD DENSE EVENT LOOKS TO BE THE LACK OF SATURATION IN THE BOUNDARY LAYER. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 256 CDT TUE SEP 24 2013 SOUTHWESTERLY FLOW SETS UP WEDNESDAY THROUGH THE END OF THE WORK WEEK AS THE UPPER LEVEL PATTERN BECOMES AMPLIFIED...PROVIDING A FEW PLEASANT AND TRANQUIL EARLY AUTUMN DAYS. A WESTERN SHORTWAVE TROUGH BEGINS TO DIG AND MOVE EASTWARD WHILE THE DOWNSTREAM RIDGE BUILDS ACROSS MUCH OF THE EASTERN CONUS. MOSTLY SUNNY TO SUNNY SKIES SHOULD PREVAIL EACH DAY...WITH A GRADUAL WARMING IN HIGH TEMPERATURES. HIGHS RANGING FROM THE LOW TO MID 70S WEDNESDAY WILL WARM TO THE UPPER 70S TO LOWER 80S BY FRIDAY. THE 24.12Z MODEL GUIDANCE MORE OR LESS DID NOT CHANGE THE SPEED AND PROGRESSION OF THE WEEKEND WEATHER SYSTEM...MAYBE A TOUCH FASTER COMPARED TO THE 00Z AND 06Z RUNS. HOWEVER...THERE IS BETTER AGREEMENT BETWEEN THE VARIOUS DETERMINISTIC MODELS THAN PREVIOUS MODEL CYCLES. IT APPEARS THAT THROUGH 15Z SATURDAY THE FORECAST AREA SHOULD BE DRY WITH INCREASING MID TO HIGH LEVEL CLOUDS. INITIAL PRECIPITATION BAND LOOKS TO SPREAD IN FROM THE WEST DURING THE LATE MORNING HOURS...MOVING INTO WESTERN WISCONSIN DURING THE EARLY/MID AFTERNOON. THE 24.12Z GFS REMAINS A BIT FASTER THAN THE 24.12Z GEM...WHILE THE 24.12Z CONTINUES TO BE SLOWER SOLUTION. THE 24.12Z ECMWF ATTEMPTS TO TURN THE UPPER LEVEL WAVE MORE NEGATIVELY TILTED SATURDAY AFTERNOON...HELPING TO PUSH THE WHOLE SYSTEM EAST OF THE AREA BY EARLY SUNDAY...IN LINE WITH ITS FASTER COUNTERPARTS. THIS SUGGESTS GOOD CONSISTENCY FOR A DRY SUNDAY...SO HAVE REMOVED CHANCES ALONG AND WEST OF THE MISSISSIPPI RIVER. IN THE WAKE OF THIS SYSTEM...ZONAL UPPER LEVEL FLOW WILL PROVIDE A COUPLE OF DAYS OF NEAR NORMAL TEMPERATURES AND TRANQUIL WEATHER. INDICATIONS IN THE 24.12Z ECMWF OF AN ACTIVE PACIFIC NORTHWEST JET SUGGESTS PIECES OF FAST MOVING ENERGY THROUGH THE FLOW...WITH A COLD FRONTAL PASSAGE TUESDAY NEXT WEEK FOLLOWED BY A REINFORCING SHOT OF COOLER AIR. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON) ISSUED AT 1220 PM CDT TUE SEP 24 2013 GENERALLY GOOD VFR CONDITIONS EXPECTED THRU MUCH OF THE NEXT 24-48 HRS. THE ONE CONCERN IS THE RADIATIONAL FOG POTENTIAL CENTERED ON 12Z WED. LIGHT WINDS WILL EXTEND FROM THE SURFACE ON UP THROUGH THE LOW LEVELS OF THE ATMOSPHERE...WHICH WHEN COMBINED WITH CLEAR SKIES SHOULD LEAD TO SOME RADIATIONAL FOG DEVELOPMENT LATE TONIGHT. SFC GRADIENT WINDS LOOK TO BE EAST-SOUTHEAST IN THE 3-5KT RANGE AROUND 12Z WED WITH THE CENTER OF THE SFC HIGH MORE OVER MICHIGAN. THESE WINDS EXPECTED TO KEEP ANY BR/FG IN ROUGHLY THE 09-14Z TIME-FRAME MOSTLY MVFR...AND ONLY CARRIED 4-5SM BR AT KLSE/KRST FOR NOW. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...ZT LONG TERM....ZT AVIATION.....RRS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1107 PM CDT MON SEP 23 2013 .SHORT TERM...(THIS EVENING THROUGH TUESDAY) ISSUED AT 258 PM CDT MON SEP 23 2013 AFTERNOON WATER VAPOR IMAGERY OVERLAID WITH RAP 500 MB ANALYSIS SHOWS RATHER DEEP NEGATIVELY TITLED UPPER LEVEL SHORTWAVE TROUGH EJECTING OUT INTO THE CENTRAL PLAINS. AT THE SURFACE...A 997 MB LOW RESIDES IN NW KANSAS WITH A NICE CURL SEEN IN VISIBLE SATELLITE IMAGERY. IT IS THIS SYSTEM THAT WILL BE LIFTING TOWARD THE UPPER MIDWEST TONIGHT INTO TUESDAY. 23.12Z GUIDANCE REMAINS SUPPORTIVE OF A DRY FORECAST WITH THIS SYSTEM AS A COMBINATION OF WEAKENING DYNAMICS AND LIMITED MOISTURE TRANSPORT LEAVES A LOT TO BE DESIRED. ACROSS THE BOARD...500-300 MB PV ADVECTION...300-310K ISENTROPIC LIFT...AND 850 MB MOISTURE TRANSPORT ALL WEAKEN OR BECOME NON-EXISTENT BETWEEN 06Z AND 15Z TUESDAY. OUTSIDE OF MID TO HIGH LEVEL CLOUDS SPREADING IN FROM THE WEST INITIALLY WITH THE WARM AIR ADVECTION WING...LITTLE TO NO IMPACT EXPECTED WITH THIS SYSTEM. PLAN ON ANOTHER PLEASANT AUTUMN DAY WITH MOSTLY TO PARTLY SUNNY SKIES AND HIGHS A COUPLE DEGREES ON EITHER SIDE OF 70F. .LONG TERM...(TUESDAY NIGHT THROUGH MONDAY) ISSUED AT 258 PM CDT MON SEP 23 2013 DRY/QUIET WEATHER TUESDAY NIGHT THROUGH FRIDAY AS RIDGE OF HIGH PRESSURE INFLUENCES THE SENSIBLE WEATHER ACROSS THE UPPER MIDWEST. BY WEDNESDAY...THE AFOREMENTIONED SYSTEM DECAYS AND SLOWS ACROSS THE MID ATLANTIC MEANWHILE A WESTERN CONUS SHORTWAVE TROUGH DIGS DOWN NEAR THE FOUR CORNERS REGION. THIS PUTS THE CENTRAL PLAINS UNDER DRY...WARMING SOUTHWESTERLY FLOW. 925 MB TEMPERATURES ARE EXPECTED TO CLIMB EACH DAY...FROM NEAR SEASONAL LEVELS WEDNESDAY TO SLIGHTLY ABOVE NORMAL BY THURSDAY...AND TO NEAR 80 IN SOME SPOTS BY FRIDAY. WEDNESDAY MORNING CONDITIONS LOOK SOMEWHAT FAVORABLE FOR RIVER VALLEY FOG AS HIGH PRESSURE CENTERS ITSELF ACROSS CENTRAL WISCONSIN. FORECAST SOUNDINGS SHOW A VERY DEEP LAYER OF LIGHT WINDS LESS THAN 10 KTS UP TO 600 MB...THOUGH THERE IS A LACK OF LOW LEVEL SATURATION...BUT COULD BE ENOUGH TO PATCHY RIVER VALLEY FOG. THE OTHER COMPETING FACTOR IS THE POSSIBILITY OF A NORTH/SOUTH ORIENTED MID LEVEL STRATUS DECK SETTING UP ALONG OR JUST WEST OF THE MS RIVER. THIS IS SEEN IN THE GFS/NAM RH FIELDS AT 850 AND 700 MB. FOR NOW...HAVE ADDED PATCHY VALLEY FOG TO MS AND WISCONSIN RIVER VALLEYS. FOCUS TURNS TO LATE FRIDAY NIGHT INTO THE UPCOMING WEEKEND SYSTEM AS THE WESTERN SHORTWAVE TROUGH MOVES INTO THE NORTHERN AND CENTRAL PLAINS. AS PIECES OF ENERGY ROUND THE SHORTWAVE TROUGH...A COUPLE OF SURFACE LOWS ARE EXPECTED TO FORM...AND EVENTUALLY DRAG A COLD FRONT THROUGH THE AREA. MOISTURE AHEAD OF THE FRONT INCREASES...AND BROAD BUT PERSISTENT ISENTROPIC LIFT ON THE 305-315K SURFACES IS SEEN. THERE IS WEAK INSTABILITY ASSOCIATED WITH THE SYSTEM...BUT MOST OF THE PRECIPITATION LOOKS TO BE POST- FRONTAL. THE POSITIVE TILTED NATURE OF THE SHORTWAVE TROUGH MAKES TIMING DETAILS A BIT UNCERTAIN AND DIFFICULT...AS THERE REMAINS SOME DISAGREEMENT BETWEEN THE 23.12Z GUIDANCE. HOWEVER...ALL GUIDANCE DID TREND MUCH SLOWER THAN PREVIOUS RUNS...THOUGH WITH VARYING DEGREES. THE GEM/ECMWF SUGGESTS MOST OF SATURDAY WOULD REMAIN DRY...HOLDING PRECIPITATION BACK UNTIL SATURDAY NIGHT OR SUNDAY. THE GFS IS A TOUCH FASTER BUT STILL SLOWER THAN ITS PREVIOUS RUN. AS A RESULT...HAVE PUSHED BACK PRECIPITATION TIMING...ESPECIALLY EAST OF THE MISSISSIPPI RIVER. STILL PLENTY OF TIME TO IRON OUT THE SPECIFICS. IN THE WAKE OF THIS SYSTEM...A RETURN TO SEASONABLY COOL AND DRY WEATHER THANKS TO CANADIAN HIGH PRESSURE BUILDING INTO THE UPPER MIDWEST. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT) ISSUED AT 1107 PM CDT MON SEP 23 2013 VFR CONDITIONS LOOK TO CONTINUE EVEN AS SLOW MOVING UPPER LOW APPROACHES FROM THE CENTRAL PLAINS. AIRMASS REMAINS VERY DRY AND WITH SYSTEM WEAKENING AS IT APPROACHES...NOT ENOUGH LIFT EXPECTED TO GENERATE MORE THAN MID LEVEL CLOUD DECK. TIMING THAT IN MAY TAKE AWHILE AS RIDGE HOLDS TOUGH TO THE EAST BUT INTRODUCED VFR CEILINGS ADVECTING IN FROM WEST TO EAST THROUGH THE DAY TUESDAY. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...ZT LONG TERM....ZT AVIATION.....SHEA
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
407 AM EDT THU SEP 26 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 406 AM EDT THU SEP 26 2013 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW A STAGNANT UPR FLOW OVER THE CONUS WITH UPR RDG OVER THE GREAT LKS SANDWICHED BTWN SLOW MOVING CLOSED LO OFF THE CANADIAN MARITIMES AND A DEEPENING TROF OVER THE WRN STATES. SFC HI PRES REMAINS ANCHORED IN QUEBEC... WITH RDG AXIS EXTENDING SWWD INTO THE UPR LKS. ALTHOUGH ABUNDANT MID LVL DRY AIR ABOVE SHARP SUBSIDENCE INVRN NEAR H9 SHOWN ON THE 00Z GRB/APX RAOBS IS BRINGING DRY WX...EFFICIENT NOCTURNAL COOLING HAS ALLOWED FOG TO FORM OVER MAINLY THE SCENTRAL COUNTIES AND THE KEWEENAW WHERE LGT E-SE FLOW ARND SFC HI PRES IS UPSLOPING OFF THE LKS. BUT IN CONTRAST TO LAST NGT...ADVECTION OF VERY DRY NEAR SFC AIRMASS SHOWN ON THE 00Z APX RAOB /PWAT 0.30 INCH/ IS TENDING TO LIMIT THE COVERAGE OF THE THICKER FOG. MAIN FCST CONCERNS IN THE SHORT TERM ARE FOG TRENDS AND TEMPS AS WELL AS THE POTENTIAL FOR MORE FOG FORMATION TNGT. EARLY THIS MRNG/TDAY...MAIN LIMITATION TO WDSPRD DENSE FOG EARLY THIS MRNG WL BE THE ADVECTION OF THE DRIER LLVL AIR SHOWN ON THE 00Z APX RAOB. SHORT TERM MODEL FCSTS SHOW THIS DRIER H95-9 AIR BLO THE SUBSIDENCE INVRN OVERSRREADING UPR MI EARLY THIS MRNG...COUNTERING TO SOME EXTENT THE IMPACT OF NOCTURNAL COOLING UNDER THE MID LVL DRY AIR. WL MAINTAIN A MENTION OF AREAS OF FOG UNTIL 13Z OVER THE SCENTRAL WITH FVRBL UPSLOPE WIND COMPONENT. AWAY FM THIS AREA...EXPECT NOTHING MORE THAN PATCHY FOG. DOWNSLOPE NATURE OF THE LLVL FLOW WL LIKELY KEEP MUCH FOG FM DVLPG NEAR LK SUP AND OVER THE FAR W ARND IWD. ISSUED SPS FOR THE SCENTRAL COUNTIES TO COVER LOCALLY DENSE FOG IN THIS AREA THRU SUNRISE...BUT AN ADVY WL NOT BE NECESSARY. ONCE ANY FOG BURNS OFF SOON AFTER SUNRISE...EXPECT MOSUNNY SKIES. WITH H85 TEMPS FCST UP TO 17C OVER THE W...MAX TEMPS THERE SHOULD TOP OUT IN THE 70S AWAY FM SOME MODERATION ON MAINLY THE E SIDE OF THE KEWEENAW IN LLVL SE FLOW. THIS SE FLOW WL TEND TO LIMIT THE DIURNAL TEMP RISE OVER THE SE COUNTIES. TNGT...THE UPR RDG AXIS IS FCST TO DRIFT ONLY SLOWLY TO THE E...WITH SFC HI OVER QUEBEC DRIFTING S INTO NEW ENGLAND. WITH FALLING MSLP IN THE PLAINS ASSOCIATED WITH SHRTWV LIFTING OUT OF THE WRN TROF...THE PRES GRADIENT/SLY FLOW IS PROGGED TO SHARPEN OVER MAINLY WRN UPR MI. THIS INCRSG S WIND IN CONCERT WITH FCST INCRSG PWAT WL RESTRICT THE DIURNAL TEMP FALL IN THIS AREA...SO TENDED TOWARD THE WARM SIDE OF GUIDANCE FOR MIN TEMPS OVER THE FAR W FM IWD INTO THE KEWEENAW. A FLATTER PRES GRADIENT/PWAT FCST AOB 0.50 INCH CLOSER TO THE SFC HI TO THE E WL SUPPORT LOWER TEMPS OVER THE INTERIOR E HALF...AND FCST LO TEMPS CLOSER TO THE LO END OF GUIDANCE IN THIS AREA. BUT SOMEWHAT STRONGER H925 WINDS UP TO 20KTS FCST IN THIS AREA WL LIKELY KEEP THE LOWS A BIT HIER THAN OBSVD THIS MRNG. WITH THE S WIND OFF LK MI... EXPECT MORE FOG TO FORM IN THIS AREA. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 406 AM EDT THU SEP 26 2013 FRIDAY WILL BE THE LAST COMPLETELY DRY DAY ACROSS THE CWA AS THE HIGH PRESSURE RIDGE THAT HAS BEEN INFLUENCING OUR WEATHER SLIDES SOUTHEAST INTO THE ATLANTIC STATES. AT THE SAME TIME...THE UPPER TROUGH CURRENTLY OVER THE WESTERN CONUS WILL EJECT OUT OF THE ROCKIES AND INTO THE CENTRAL AND NORTHERN PLAINS. A SHORTWAVE EXITING THIS UPPER TROUGH WILL MOVE NORTHEAST THROUGH THE CANADIAN PRAIRIES WITH AN ASSOCIATED SURFACE LOW THAT LEAVE AN ELONGATED SURFACE TROUGH STRETCHING SOUTH THROUGH MINNESOTA AND INTO THE CENTRAL PLAINS. SINCE THAT WILL BE THE MAIN FOCUS OF THE PRECIPITATION ON FRIDAY AND THE AREA STILL UNDER THE DRY AIR OF THE HIGH...SHOULD SEE ANOTHER MOSTLY SUNNY DAY ACROSS THE CWA. LATE IN THE AFTERNOON...COULD SEE SOME MID-HIGH CLOUDS AFFECTING WESTERN UPPER MICHIGAN. WITH THE SUNSHINE...SHOULD SEE ANOTHER DAY OF ABOVE NORMAL HIGHS WITH TEMPERATURES IN THE UPPER 60S TO MIDDLE 70S. IT SHOULD BE A LITTLE BREEZY ON FRIDAY DUE TO THE INCREASING PRESSURE GRADIENT BETWEEN THE HIGH AND THE APPROACHING TROUGH...ESPECIALLY OVER THE WEST WHERE THERE COULD BE GUSTS TO 25-30MPH. EXPECT BREEZY CONDITIONS TO CONTINUE AT TIMES FRIDAY NIGHT INTO SATURDAY UNTIL THE FRONT MOVES THROUGH. THIS DRY AIR WILL REMAIN THROUGH FRIDAY NIGHT AND INTO SATURDAY MORNING...WITH ONLY A FEW SHOWERS BRUSHING FAR WESTERN LAKE SUPERIOR DURING THAT TIME. THEN...AS THE UPPER TROUGH EJECTS OUT OF THE FOUR CORNERS REGION FRIDAY NIGHT...IT PULLS THE ENTIRE UPPER TROUGH WITH IT AND THROUGH THE UPPER GREAT LAKES REGION THROUGH SUNDAY. IN ADDITION...A SECONDARY LOW WILL DEVELOP ALONG THE TROUGH NEAR WESTERN LAKE SUPERIOR AND THE MN ARROWHEAD AS THE RIGHT REAR OF THE UPPER JET SLIDES NORTHEAST THROUGH THE AREA. THIS WILL ALLOW A LINE OF SHOWERS ORIENTATED NORTH-SOUTH ALONG AND BEHIND THE TROUGH TO MOVE EAST-NORTHEAST ACROSS UPPER MICHIGAN. AS HAS BEEN THE CASE OVER THE LAST SEVERAL NIGHT...THE GFS REMAINS THE FASTEST WITH THE ARRIVAL OF THE TROUGH/SHOWERS...WHILE THE GEM/ECMWF ARE MORE CONSISTENT WITH THE SLOWER ARRIVAL. THE NAM ALSO FOLLOWS ALONG WITH THE FASTER ARRIVAL SHOWN IN THE GFS. SINCE THERE IS AN EVEN SPLIT IN ARRIVAL TIMES AND ONLY 50-75MI SPREAD...WILL SPLIT THE DIFFERENCE AT THIS POINT AND HAVE THE WESTERN THIRD/HALF OF UPPER MICHIGAN SEEING RAIN BY SUNSET AND THEN IT SPREADING ACROSS THE REST OF THE CWA SATURDAY EVENING. WITH THE DIFFERENCES IN SPEED...ALSO FOLLOWED THE SIMILAR IDEA FOR THE BACK SIDE OF THE RAIN OVERNIGHT SATURDAY. STILL APPEARS LIKE A DECENT OPPORTUNITY FOR A QUARTER INCH OF RAIN OVER MUCH OF THE CWA...ALTHOUGH IT WILL LIKELY FALL IN A 2-3HR PERIOD. FINALLY...THUNDER POTENTIAL STILL LOOKS TO BE VERY LIMITED...ESPECIALLY WITH MUCH OF THE RAIN EXPECTED TO BE POST-FRONTAL. THERE ARE A COUPLE SMALL POCKETS OF 700-500MB LAPSE RATES APPROACHING 6.5C/KM AHEAD OF THE FRONT AND SIMILAR POCKETS OF MUCAPE NEAR 250 J/KG. IF A RUMBLE OF THUNDER OCCURS...BELIEVE IT WOULD BE IN THE WESTERN U.P. IN THE AFTERNOON. BUT...SINCE COVERAGE SHOULD BE VERY ISOLATED...OPTED TO REMOVE THE SLIGHT CHANCE OF THUNDER. WEAK UPPER RIDGE WILL QUICKLY BUILD IN ON SUNDAY AFTERNOON AND REMAIN INTO MONDAY. THIS WILL LEAD TO ANOTHER DRY PERIOD OF WEATHER. THERE MAY BE A SOME POST-FRONTAL CLOUDS SUNDAY AFTERNOON AS A POCKET OF COOLER TEMPERATURES ALOFT MOVE THROUGH. ECMWF/GEM SEEM TO LIKE THAT IDEA...WHILE GFS KEEPS THINGS CLEAR. SINCE THAT MOISTURE AND COOLER AIR WILL BE QUICKLY PULLING OUT ON SUNDAY...WITH FOLLOW THE GENERAL IDEA OF DECREASING CLOUDS ON SUNDAY. HIGHS WILL BE COOLER ON SUNDAY WITH THAT COLD POCKET OF AIR...BUT STILL THINK THEY WILL END UP IN THE LOWER-MID 60S IN MOST LOCATIONS (WHICH IS NORMAL FOR THIS TIME OF YEAR). TEMPERATURES SHOULD WARM BACK ABOVE NORMAL ON MONDAY WITH HIGHS IN THE UPPER 60S AND LOWER 70S...AS 850MB TEMPERATURES PUSH BACK INTO THE LOWER TEENS. CONUS LOOKS TO COME UNDER ZONAL FLOW FOR TUESDAY AND PART OF WEDNESDAY...AS THE UPPER JET RUNS WEST-EAST ACROSS THE NORTHERN ROCKIES. THIS SHOULD KEEP THE MAIN SYNOPTIC FEATURES LOCKED IN CANADA AND POSSIBLY JUST BRUSHING THE AREA AT TIMES MONDAY NIGHT THROUGH TUESDAY NIGHT. THIS WILL ALSO KEEP THE AREA UNDER ABOVE NORMAL TEMPERATURES. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 131 AM EDT THU SEP 26 2013 MAIN FOCUS FOR THE PERIOD IS THE POTENTIAL FOR ANOTHER ROUND OF NOCTURNAL FOG EARLY THIS MRNG. THE MAIN LIMITING FACTOR AGAINST SGNFT FOG FORMATION IS THE VERY DRY LLVL AIR SHOWN ON THE 00Z APX RAOB. MODELS IN GOOD AGREEMENT SHOWING SE FLOW ARND SFC HI PRES OVER CANADA ADVECTING THIS DRIER AIR INTO UPR MI. SO ALTHOUGH THERE MAY BE SOME SHALLOW FOG AT MAINLY SAW WITH AN UPSLOPE WIND COMPONENT... IFR CONDITIONS EVEN THERE LOOK TO BE TRANSIENT. DOWNSLOPE NATURE OF THE LLVL FLOW IN TANDEM WITH THE NEAR SFC DRY ADVECTION WL PROBABLY KEEP FOG FM FORMING AT IWD AND RESTRICT INTENSITY AS WELL AT CMX. ANY FOG WL ERODE QUICKLY AFTER SUNRISE AND GIVE WAY TO VFR WX WITH THE HI PRES DOMINATING. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 406 AM EDT THU SEP 26 2013 HIGH PRESSURE OVER WESTERN QUEBEC WILL CONTINUE TO DOMINATE THE WEATHER FOR TODAY...ALTHOUGH IT WILL BEGIN TO SLIDE SOUTHEAST TONIGHT. BEFORE THIS OCCURS...THERE IS AN AREA OF FOG (LOCALLY DENSE) OVER THE WESTERN LAKE EARLY THIS MORNING AND EXPECT THAT TO DIMINISH THIS MORNING AS DRIER AIR SLIDES IN FROM THE SOUTHEAST. MEANWHILE...A LOW PRESSURE SYSTEM MOVING NORTHEAST OUT OF THE NORTHERN PLAINS TODAY WILL LINGER A TROUGH EASTERN DAKOTAS TONIGHT AND THEN SLOWLY MOVE EAST ACROSS MINNESOTA ON FRIDAY. AS THIS OCCURS...THE PRESSURE GRADIENT AND THUS SOUTHERLY WINDS WILL INCREASE OVER LAKE SUPERIOR ON FRIDAY. THESE STRONGER WINDS...TO 25KTS...WILL CONTINUE FRIDAY NIGHT AND SATURDAY UNTIL THE TROUGH MOVES THROUGH LATE SATURDAY AFTERNOON AND EVENING. BEHIND THE TROUGH...THERE COULD BE A BRIEF PERIOD OF STRONGER WESTERLY WINDS TO 25KTS OVER NORTH CENTRAL LAKE SUPERIOR OVERNIGHT SATURDAY NIGHT INTO EARLY SUNDAY MORNING. WEAK HIGH PRESSURE WILL BUILD IN TO THE UPPER GREAT LAKES ON SUNDAY NIGHT AND MONDAY AND LOWER WINDS BELOW 20KTS. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...KC LONG TERM...SRF AVIATION...KC MARINE...SRF
AREA FORECAST DISCUSSION
NWS DULUTH MN
317 AM CDT THU SEP 26 2013 .SHORT TERM...(TODAY THROUGH FRIDAY AFTERNOON) ISSUED AT 315 AM CDT THU SEP 26 2013 MAIN CHALLENGES IN THE SHORT TERM ARE CENTERED AROUND THE DENSE FOG AROUND LAKE SUPERIOR THIS MORNING...THE GUSTY SE WINDS EXPECTED THIS AFTERNOON...AND COOLER AFTERNOON TEMPERATURES AROUND THE LAKE. THE FOCUS LATE TONIGHT AND THROUGH THE DAY FRIDAY THEN SHIFTS TO PRECIP CHANCES MOVING IN WITH THE NEXT LOW PRESSURE SYSTEM APPROACHING FROM THE SW. UPPER LEVEL RIDGE AMPLIFYING OVER THE WRN GREAT LAKES THIS MORNING AS WEAK HIGH PRESSURE AT THE SFC TO THE EAST SLOWLY ADVANCES OUT OF THE AREA. A DEEPENING LONGWAVE TROUGH OVER THE INTER-MOUNTAIN WEST IS EJECTING A FEW SHRT WVS INTO THE NRN PLAINS THIS MORNING AND TRIGGERING A FEW SHOWERS AND STORMS ALONG A N-S ORIENTED FRONTAL ZONE EXTENDING FROM FAR SERN SASKATCHEWAN INTO THE WRN DAKOTAS AND WRN NEB. A FEW HIGH CLOUDS ARE STREAMING IN ACROSS THE FAR WRN COUNTIES OF THE CWA...BUT THE MAIN CONCERN THIS MORNING IS THE AREAS OF FOG...DENSE IN SOME LOCATIONS...AROUND LAKE SUPERIOR. A DENSE FOG ADVISORY WAS ISSUED YESTERDAY FOR THE PERIPHERY OF THE LAKE...HOWEVER ENOUGH DRY AIR ENTRAINMENT AND MIXING THROUGH THE OVERNIGHT HAS ALLOWED A GOOD PORTION OF THE FOG TO ADVECT AWAY FROM THE SOUTH SHORE...AND LEAVE THE MAIN AREA OF DENSE FOG CONFINED TO THE NORTH SHORE. SO...DECIDED TO CANCEL THE ADVISORY FOR THE SOUTH SHORE AND LET IT RIDE FROM DULUTH TO GRAND PORTAGE UNTIL 9 AM. THERE IS ALSO AN AREA OF FOG DEVELOPING IN N-CNTRL WI WITHIN THE LAST HOUR...WILL NEED TO WATCH THIS AS THE MORNING PROGRESSES. AN INITIAL BATCH OF HIGH CLOUDS ASSOCIATED WITH A PASSING S/W THROUGH THE NRN PLAINS WILL LIFT NWD TODAY AND LEAVE MUCH OF THE AREA UNDER MOSTLY SUNNY SKIES. A FEW LOW CLOUDS COULD LINGER ALONG THE NORTH SHORE UNDER THE INFLUENCE OF SE WINDS OFF THE LAKE. STRONG MIXING THIS AFTERNOON...ESPECIALLY ACROSS NE MN WILL ALLOW WINDS TO INCREASE OUT OF THE S/SE. SHOULD SEE SUSTAINED WINDS AROUND 15 TO 20 MPH...AND GUSTS UP TO 25 MPH. THE STRONGEST WINDS WILL BE AROUND THE BRAINERD LAKES AREA...WITH LIGHTER WINDS ELSEWHERE. STRONG WAA WILL ALSO ALLOW TEMPERATURES TO WARM WELL INTO THE 70S. THE EXCEPTION WILL BE ALONG THE NORTH SHORE WHERE A LAKE BREEZE WILL KEEP TEMPS IN THE UPPER 50S AND LOWER 60S. ADDITIONAL CLOUD COVER WILL MOVE IN TONIGHT AS THE UPPER TROUGH MOVES THROUGH THE SRN ROCKIES AND A SFC LOW DEVELOPS OVER THE SRN PLAINS AND LIFTS NEWD INTO THE UPPER MIDWEST. THIS SFC FEATURE WILL MOVE NEWD INTO THE NORTHLAND AS AN ELONGATED SFC TROUGH AND PRODUCE SHOWERS AND THUNDERSTORMS THROUGH THE DAY FRIDAY. THE BEST CHANCE FOR STORMS WILL BE IN THE AFTERNOON WHEN THE SFC FRONT INTERACTS WITH ENOUGH BL INSTABILITY TO PRODUCE MODERATE CONVECTION. TEMPERATURES WILL WARM INTO THE 70S AND LOWER 80S ON FRIDAY...AS LOW LEVEL MOISTURE INCREASES AND LAPSE RATES STEEPEN OVER CENTRAL AND NRN MN. SECTIONS OF NE MN ARE HIGHLIGHTED IN THE SPC DAY 2 CONVECTIVE OUTLOOK. .LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 315 AM CDT THU SEP 26 2013 NAM/GFS ARE THE QUICKEST WITH THE SFC LOW/COLD FRONT THAT WILL AFFECT THE FA FRIDAY NIGHT THROUGH SATURDAY NIGHT. ECMWF/GEM ARE SLOWER AND PREFERRED WITH THE HANDLING OF THIS SYSTEM. RAIN SHOULD REACH THE WESTERN THIRD OF THE FA FRIDAY EVENING AND FALL MAINLY WEST OF HIGHWAY 53 THROUGH THE REST OF FRIDAY NIGHT. WILL STILL CARRY A MENTION OF ISOLD THUNDER WITH WEAK INSTABILITY. ON SATURDAY...RAIN WILL PROGRESS ACROSS THE ENTIRE FA...BUT NOT REACHING THE TIP OF THE ARROWHEAD AND EASTERN PORTION OF WI COUNTIES UNTIL AFTERNOON. WHAT INSTABILITY WAS AVAILABLE HAS NOW DIMINISHED AND WILL CARRY A MENTION OF ALL RAIN. THE COLD FRONT WILL MOVE QUICKLY THROUGH THE AREA SATURDAY EVENING AND EXIT BY 12Z SUNDAY. HAVE LINGERED SOME POPS SATURDAY EVENING OVER THE NORTH AND EAST IN THE VCNTY OF THE FRONT AND SFC LOW AND REMOVED FROM THE OVERNIGHT. A DRY PERIOD IS IN STORE SUNDAY THROUGH MONDAY NIGHT. MODEL DIFFERENCES SHOW UP WITH A COLD FRONT MOVING ACROSS THE WESTERN GREAT LAKES ON TUESDAY AND ASSOCIATED RAIN. HAVE GONE WITH A COMPROMISE FOR POPS. DRY CONDITIONS RETURN TUESDAY NIGHT AND WEDNESDAY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1150 PM CDT WED SEP 25 2013 STRATUS AND FOG AROUND LAKE SUPERIOR CONTINUED TO EXPAND WEST AND NORTH LATE THIS EVENING...WITH THE STRATUS DIMINISHING IN COVERAGE FROM THE EAST. THE MEAN LOW LEVEL FLOW IS FORECAST TO VEER TO MORE SOUTHERLY TONIGHT AND INCREASE. THIS SHOULD HELP PUSH THE FOG AND LOWER CEILINGS NORTH...AND WILL CAUSE THEM TO DIMINISH ALONG THE SOUTH SHORE...PERHAPS INTO KDLH AS WELL LATE. THE HRRR IS PICKING UP ON THIS TREND LATER TONIGHT. AT THIS TIME...WE KEPT LIFR CONDITIONS IN THE KDLH TAF AS CONFIDENCE ON WHEN/IF CONDITIONS IMPROVE IS LOW. MUCH OF THE FOG/STRATUS WILL LIFT BY 15Z...LINGERING LONGER ALONG THE NORTH SHORE. GUSTY SOUTHEAST/SOUTH WINDS WILL DEVELOP DURING THE DAY THURSDAY WITH VFR CONDITIONS. KBRD SOUNDING SHOWS 34KT AT THE TOP OF THE MIXED LAYER AROUND 870MB. && .PRELIMINARY POINT TEMPS/POPS... DLH 68 57 75 59 / 0 0 30 20 INL 76 59 71 53 / 0 10 70 80 BRD 79 63 73 57 / 0 20 60 80 HYR 74 54 77 61 / 0 0 10 10 ASX 72 55 78 61 / 0 0 10 10 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR MNZ020-021- 037. WI...NONE. LS...NONE. && $$ SHORT TERM...BJT LONG TERM...GSF AVIATION...MELDE
AREA FORECAST DISCUSSION
NWS DULUTH MN
1152 PM CDT WED SEP 25 2013 .UPDATE... ISSUED AT 1150 PM CDT WED SEP 25 2013 FOG AND STRATUS CONTINUED LATE THIS EVENING AROUND LAKE SUPERIOR...ESPECIALLY FROM ABOUT ASHLAND TO THE TWIN PORTS TO GRAND RAPIDS AND NORTHEAST ALONG THE NORTH SHORE. THE CLOUDS/FOG WAS EXPANDING ACROSS THE RANGE AS WELL. THE LOW LEVEL FLOW IS FORECAST TO VEER TO MORE SOUTH/SOUTHEAST OVERNIGHT AND INCREASE. THIS WILL CAUSE THE STRATUS/FOG TO RETREAT/DISSIPATE ACROSS PORTIONS OF THE SOUTH SHORE LATER TONIGHT. THIS MAY ALSO MAKE IT INTO THE TWIN PORTS LATE. AT THIS TIME...WE`LL LEAVE THE DENSE FOG ADVISORY AS IS...BUT LATER SHIFTS MAY BE ABLE TO CUT BACK THE SOUTHERN PORTION. && .SYNOPSIS... ISSUED AT 328 PM CDT WED SEP 25 2013 LAKE SUPERIOR DOMINATED BY LOW STRATUS/FOG LAYER WHILE INLAND AREAS ARE SUNNY UNDER A DRY AIR MASS AND HIGH PRESSURE. MAJOR UPPER TROF OVER INTERMOUNTAIN WEST IS AMPLIFYING COURTESY OF 140KT UPPER JET ON SWRN FLANK OF CIRCULATION. A SWRLY MID LVL FLOW IS CURRENTLY IN PLACE ACROSS THE CWA. AN AREA OF MID CLOUDS ASSOCIATED WITH A WEAK SHORTWAVE FEATURE ALOFT IS MOVING INTO THE WRN CWA. WARM ADVECTION REGIME CONTINUES TO INCREASE OVER THE CWA AS CYCLOGENESIS IS UNDERWAY OVER WRN HI PLAINS. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 328 PM CDT WED SEP 25 2013 TONIGHT...EXPECT AREA OF CLOUDS/FOG OVER LAKE SUPERIOR TO ADVECT INLAND AS SFC HEATING DECREASES. LATEST HRRR 3KM SHOWS HIGHEST PROB OF LOWEST VIS ALONG NSHORE...TWIN PORTS...AND CHEQUAMEGON BAY.WILL ISSUE A DENSE FOG ADVISORY CONSIDERING THE PRESENCE OF THE DENSE FOG OVER THE LAKE AND ITS LIKELY PENETRATION INLAND. LATEST HI-RES MDLS SUGGEST FOG BANK MAY TRY TO SHIFT FARTHER NORTH AND WEST OVERNIGHT. ELSEWHERE WILL USE PATCHY FOG FOR POTENTIAL OF LIGHT WINDS/SATURATION IN NEAR SFC LAYER. TOMORROW...DENSE FOG EXPECTED TO PERSIST NEAR LAKE SUPERIOR THROUGH EARLY MORNING. MAIN ISSUE TOMORROW WILL BE INCREASE IN GUSTY SE WINDS. LATEST BUFKIT MOMENTUM PROFILES INDICATE GUSTS TO 35 AND POSSIBLY AN ISOLATED 40 MPH ARE POSSIBLE OVER NE MN ZONES BY AFTN. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 328 PM CDT WED SEP 25 2013 ON THURSDAY NIGHT...A SHARP UPPER LEVEL RIDGE WILL EXTEND THROUGH THE CENTRAL PLAINS...INTO THE JAMES BAY AREA NEAR HUDSON BAY. MEANWHILE...A LONGWAVE TROUGH WILL BE LOCATED IN THE FAR SOUTHWESTERN UNITED STATES. IN BETWEEN WE WILL BE IN SW FLOW. THE MODELS ARE HINTING AT A LOW PRESSURE SYSTEM DEVELOPING IN THE HIGH PLAINS THURSDAY NIGHT AND FRIDAY...WITH A FRONT OR SURFACE TROUGH EXTENDING NORTHEASTWARD INTO MINNESOTA. QPF AMOUNTS VARY...BUT THE GENERAL CONSENSUS IS THAT THERE WILL BE SOME LIGHT PRECIPITATION ACROSS THE MN SIDE OF OUR CWA. THE LONGWAVE TROUGH EDGES EASTWARD ON FRIDAY...BRINGING A POTENTIALLY MORE SUBSTANTIAL CHANCE OF PRECIPITATION TO THE CWA. THE BEST CHANCE OF RAIN AND EMBEDDED THUNDERSTORMS WOULD BE IN THE MN SIDE ONCE AGAIN. A SHORTWAVE AND UPPER LEVEL VORT MAX WILL LIFT INTO THE UPPER RED RIVER VALLEY AND WESTERN GREAT LAKES REGION FRIDAY NIGHT AND SATURDAY...BRINGING A WET PERIOD TO THE WESTERN GREAT LAKES FRIDAY NIGHT AND SATURDAY. THE GFS IS FASTEST AT PUSHING THE SYSTEM OUT OF THE AREA ON SATURDAY...WITH THE GEM AND ECMWF BEING SLOWER. WILL USE A BLEND OF THE ABOVE MODELS FOR THE MOST PART. BY SUNDAY...A MORE ZONAL FLOW ESTABLISHES ITSELF ACROSS THE NORTH CENTRAL UNITED STATES. SUNDAY INTO TUESDAY LOOKS LIKE IT WILL BE GENERALLY DRY ACROSS THE REGION...WITH A CHANCE OF SHOWERS IN ONLY A FEW LOCATIONS THROUGH WEDNESDAY AS WELL. TEMPERATURES WILL GENERALLY BE ABOVE NORMAL WITH HIGHS IN THE 60S AND EVEN SOME LOWER TO MIDDLE 70S. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1150 PM CDT WED SEP 25 2013 STRATUS AND FOG AROUND LAKE SUPERIOR CONTINUED TO EXPAND WEST AND NORTH LATE THIS EVENING...WITH THE STRATUS DIMINISHING IN COVERAGE FROM THE EAST. THE MEAN LOW LEVEL FLOW IS FORECAST TO VEER TO MORE SOUTHERLY TONIGHT AND INCREASE. THIS SHOULD HELP PUSH THE FOG AND LOWER CEILINGS NORTH...AND WILL CAUSE THEM TO DIMINISH ALONG THE SOUTH SHORE...PERHAPS INTO KDLH AS WELL LATE. THE HRRR IS PICKING UP ON THIS TREND LATER TONIGHT. AT THIS TIME...WE KEPT LIFR CONDITIONS IN THE KDLH TAF AS CONFIDENCE ON WHEN/IF CONDITIONS IMPROVE IS LOW. MUCH OF THE FOG/STRATUS WILL LIFT BY 15Z...LINGERING LONGER ALONG THE NORTH SHORE. GUSTY SOUTHEAST/SOUTH WINDS WILL DEVELOP DURING THE DAY THURSDAY WITH VFR CONDITIONS. KBRD SOUNDING SHOWS 34KT AT THE TOP OF THE MIXED LAYER AROUND 870MB. && .PRELIMINARY POINT TEMPS/POPS... DLH 49 72 56 75 / 0 0 10 10 INL 50 75 57 69 / 0 0 10 70 BRD 53 81 61 72 / 0 0 10 40 HYR 43 74 57 79 / 0 0 0 10 ASX 46 72 57 78 / 0 0 0 10 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...DENSE FOG ADVISORY UNTIL 9 AM CDT THURSDAY FOR MNZ020-021-037. WI...DENSE FOG ADVISORY UNTIL 9 AM CDT THURSDAY FOR WIZ001>004. LS...DENSE FOG ADVISORY UNTIL NOON CDT THURSDAY FOR LSZ121-140>148. && $$ UPDATE...MELDE SYNOPSIS...CANNON SHORT TERM...CANNON LONG TERM...DAP AVIATION...MELDE
AREA FORECAST DISCUSSION
NWS BISMARCK ND
249 AM CDT THU SEP 26 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 249 AM CDT THU SEP 26 2013 MAIN CONCERN TODAY WILL BE THUNDERSTORMS EARLY THIS MORNING FOLLOWED BY A WIND ADVISORY SOUTHWEST THROUGH NORTH CENTRAL. HAVE UTILIZED A BLEND OF ALL MODELS...BUT SPECIFICALLY THE HRRR FOR AREAL COVERAGE OF PRECIPITATION THIS MORNING AND NAM/GFS FOR THE WIND ADVISORY. THE LATEST WATER VAPOR IMAGERY ALONG WITH SPC MESOSCALE ANALYSIS CONTINUES TO SHOW THE H3 JET STREAK WORKING ITS WAY THROUGH WYOMING AND INTO SOUTH DAKOTA. UPPER DIVERGENCE FIELD ASSOCIATED WITH THE LEFT EXIT REGION CENTERED OVER CENTRAL/NORTHERN NORTH DAKOTA AS ISOLATED THUNDERSTORMS CONTINUE TO ESCALATE UPWARDS. SURFACE LOW PRESSURE IN SOUTHERN SOUTH DAKOTA WILL BEGIN TO MOVE NORTH ALONG A COLD FRONT WHICH IS NOW LOCATED FROM NEAR OXBOW SASKATCHEWAN...SOUTH TO MINOT AND INTO LEMMON SOUTH DAKOTA. AS THE JET STREAK AND UPPER DIVERGENCE FIELD SHIFT FURTHER NORTH THROUGH THE MORNING...THE SURFACE LOW WILL DEEPEN AS IT ENTERS SOUTHERN SASKATCHEWAN THIS AFTERNOON. A TIGHT PRESSURE GRADIENT WILL ENSUE...RESULTING IN A MARGINAL WIND ADVISORY EVENT. WITH SUSTAINED WINDS VERY NEAR 30 MPH AND GUSTS TO 40 MPH OVER A FAIRLY LARGE AREA...DECIDED TO ISSUE A WIND ADVISORY FOR THE SOUTHWEST AND NORTH CENTRAL ZONES. WINDS WILL INCREASE FIRST ACROSS THE SOUTHWEST LATE THURSDAY MORNING...THEN TRANSLATE INTO NORTH CENTRAL BEGINNING IN THE EARLY AFTERNOON. WINDS WILL THEN DIMINISH FROM SOUTH TO NORTH THURSDAY EVENING. AS FAR AS SHOWERS AND THUNDERSTORMS...THERE WILL BE A DIMINISHING EFFECT AS THE SURFACE LOW MOVES FROM SOUTH TO NORTH TODAY. MAIN INSTABILITY WASHES OUT BY 18Z IN THE NORTH AND HAVE ENDED THE THUNDERSTORM THREAT IN THE GRIDDED FORECAST AT THAT TIME. DRY WEATHER COMMENCES CENTRAL AND SOUTH TODAY INTO EARLY TONIGHT. THE NEXT ROUND OF SHOWERS BEGINS IN THE SOUTHWEST EARLY TONIGHT AND GRADUALLY EXPANDS NORTHEAST OVERNIGHT. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 249 AM CDT THU SEP 26 2013 THE MAIN FORECAST ISSUE IN THE LONG TERM PERIOD WILL BE PRECIPITATION CHANCES AND PLACEMENT FRIDAY THROUGH SATURDAY MORNING. THERE IS STILL SOME DISAGREEMENT AMONG THE DETERMINISTIC MODELS WITH PRECIPITATION ACROSS NORTH DAKOTA ON FRIDAY. HOWEVER...THERE IS MUCH BETTER AGREEMENT FRIDAY NIGHT INTO SATURDAY MORNING. WE BEGIN THE LONG TERM PERIOD ON FRIDAY WITH AN UPPER LEVEL TROUGH OVER THE NORTHERN AND CENTRAL ROCKIES. SHEARED VORTICITY ALONG THE LEADING EDGE OF THE TROUGH EXTENDS ACROSS EASTERN MONTANA AND WESTERN NORTH DAKOTA. THE ECMWF IS SHOWING A BROAD AREA OF LIGHT TO MODERATE RAIN LIFTING SOUTHWEST TO NORTHEAST ACROSS THE FORECAST AREA...WHILE THE GFS/GEM CONTINUE TO INDICATE TWO SEPARATE AREAS OF PRECIPITATION...ONE OVER THE WESTERN DAKOTAS ASSOCIATED WITH THE UPPER LEVEL TROUGH...AND ANOTHER OVER EASTERN NORTH DAKOTA ASSOCIATED WITH THE SURFACE SYSTEM...AND A DRY SLOT OVER CENTRAL NORTH DAKOTA. DUE TO CONTINUED DIFFERENCES...WILL SETTLE ON A BROAD BRUSH OF CHANCE TO HIGH CHANCE POPS UNTIL THERE IS BETTER MODEL AGREEMENT. EITHER WAY IT WILL BE QUITE COOL AND CLOUDY WITH SCATTERED LIGHT RAIN AND HIGHS MAINLY IN THE 50S. THERE IS BETTER MODEL AGREEMENT AS THE KICKER SHORTWAVE ROUNDS THE BASE OF THE UPPER TROUGH AND LIFTS INTO THE CENTRAL PLAINS FRIDAY NIGHT. STRONG 2D FRONTOGENESIS SETS UP OVER THE EASTERN DAKOTAS FRIDAY NIGHT AS THE SURFACE LOW TRACKS FROM THE CENTRAL PLAINS INTO NORTHERN MINNESOTA BY SATURDAY MORNING. THIS RESULTS IN AN ENHANCED BAND OF DEFORMATION RAIN OVER FAR SOUTH CENTRAL NORTH DAKOTA THROUGH THE JAMES RIVER VALLEY AND INTO EASTERN NORTH DAKOTA. THE RAIN WILL EXIT THE JAMES RIVER VALLEY SATURDAY MORNING WITH CLEARING SKIES OVER WESTERN NORTH DAKOTA. WE WILL NEED TO MONITOR FOR POSSIBLE FROST HIGHLIGHTS ACROSS THE WEST ON SATURDAY MORNING WITH LOWS POSSIBLY FALLING INTO THE MID TO UPPER 30S IF SKIES CLEAR AND WINDS SUBSIDE. UPPER LEVEL RIDGING BUILDS OVER THE AREA THROUGH THE REMAINDER OF THE WEEKEND WITH TEMPERATURES WARMING INTO THE 70S BY SUNDAY AND MONDAY. A QUASI-ZONAL FLOW THEN TAKES SHAPE THROUGH MID WEEK WITH THE STORM TRACK SITUATED NORTH OF THE BORDER. THUS MAINLY DRY CONDITIONS ARE EXPECTED EARLY NEXT WEEK. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1206 AM CDT THU SEP 26 2013 SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE OVERNIGHT FOR ALL AERODROMES EXCEPT KJMS. A COLD FRONT JUST WEST OF KMOT AND KBIS WILL SLOWLY MOVE EAST THURSDAY. A PERIOD OF MVFR CIGS TOWARD 10Z AND 12Z THURSDAY ARE FORECAST TO DEVELOP...WITH KJMS BARELY REMAINING IN THE LOW VFR RANGE. GUSTY SOUTHWEST TO WESTERLY WINDS ARE FORECAST THURSDAY...BETWEEN 20KT AND 32KT. && .BIS WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY FROM NOON CDT /11 AM MDT/ TODAY TO 7 PM CDT /6 PM MDT/ THIS EVENING FOR NDZ018-019-021-031>033-040-041-043-044. WIND ADVISORY FROM 2 PM THIS AFTERNOON TO 9 PM CDT THIS EVENING FOR NDZ002>004-010>012. && $$ SHORT TERM...KS LONG TERM...TWH AVIATION...KS
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1206 AM CDT THU SEP 26 2013 .UPDATE... ISSUED AT 1206 AM CDT THU SEP 26 2013 THE LATEST WATER VAPOR LOOP AND SPC MESOANALYSIS SHOW A H3 120KT JET PUNCHING INTO CENTRAL AND EASTERN WYOMING WITH A DIVERGENCE ALOFT FIELD CENTERED OVER WESTERN NORTH DAKOTA ASSOCIATED WITH THE LEFT EXIT REGION. SURFACE COLD FRONT SLICING NORTH TO SOUTH...FROM NEAR KENMARE SOUTH TO HAZEN AND INTO LEMMON SOUTH DAKOTA. LOW PRESSURE WAS ANALYZED OVER SOUTHWESTERN SOUTH DAKOTA WITH 3HR PRESSURE FALLS NON-EXISTENT ACROSS NORTH DAKOTA SUGGESTING CONVECTION CURRENTLY IN THE WEST IS ELEVATED ABOVE THE SURFACE. THUS FAR THE THUNDERSTORMS HAVE REMAINED BELOW SEVERE LIMITS. PEAK WINDS HAVE BEEN 34 MPH NEAR RAY. MARGINAL MID LEVEL LAPSE RATES WITH THE STRONGEST DOWNDRAFT CAPE DISPLACED FROM THE MAIN AREA OF CONVECTION AS THE AXIS IS IN CENTRAL NORTH DAKOTA. WILL MAINTAIN A MENTION OF SEVERE OVERNIGHT AS THE SURFACE LOW CONTINUES TO LIFT NORTH AND SOME HIGHER REFLECTIVITY`S NOW EMERGING OVER WESTERN SOUTH DAKOTA. EXPANDED POPS FURTHER NORTH AND EAST PER LATEST HRRR. UPDATE ISSUED AT 1013 PM CDT WED SEP 25 2013 LATE EVENING UPDATE MAINLY FOR POPS BASED ON CURRENT RADAR TRENDS. THUNDERSTORMS HAVE OVERSPREAD MUCH OF WESTERN NORTH DAKOTA. THUS FAR...STORMS HAVE REMAINED NON-SEVERE. CANNOT RULE OUT AN ISOLATED SEVERE STORM OVERNIGHT...MAINLY IN THE FORM OF WIND AS POTENTIAL EXISTS FOR STRONG FLOW ALOFT TO BE TRANSPORTED TO THE LOW LEVELS BRIEFLY. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 335 PM CDT WED SEP 25 2013 THE PRIMARY FORECAST CHALLENGE CONTINUES TO BE THE SEVERE WEATHER CHANCES ACROSS WESTERN AND NORTH CENTRAL NORTH DAKOTA TONIGHT. SHORT RANGE MODEL GUIDANCE CONTINUES TO PROG A SHORTWAVE TO LIFT NORTH ACROSS EASTERN MONTANA AND NORTHWESTERN NORTH DAKOTA TONIGHT. ITS ATTENDANT SURFACE TROUGH AXIS WILL TIGHTEN UP ACROSS WESTERN NORTH DAKOTA THIS EVENING AS A RESULT. FURTHERMORE...MODEL MUCAPE VALUES ARE FORECAST TO RANGE BETWEEN 200-400 J/KG WHILE DEEP LAYER SHEAR WILL BE UP TO 50 KNOTS. EVEN THOUGH INSTABILITY IS NOT TERRIBLY IMPRESSIVE...THE COMBINATION OF LOW-LEVEL MOISTURE CONVERGENCE AND HIGH SHEAR ENVIRONMENT WILL LIKELY BE ENOUGH TO GENERATE SEVERE THUNDERSTORMS THIS EVENING. THE LATEST 4KM WRF-NMM AND 3KM HRRR PROG AN MCS TO DEVELOP OVER SOUTHEASTERN MONTANA AROUND 01Z. THIS COMPLEX IS THEN PROGGED TO LIFT NORTH ACROSS WESTERN NORTH DAKOTA THIS EVENING. THE HI-RES MODELS ARE HINTING AT THE MCS MORPHING INTO AN MCV BY THE END OF ITS CYCLE...GENERATING MORE OF A WIND THREAT. HOWEVER...IF UPDRAFTS GET STRONG ENOUGH...LARGE HAIL CANNOT BE RULED OUT. CONTINUED TO INDICATE LARGE HAIL AND DAMAGING WINDS IN THE AFFECTED ZONES FOR TONIGHT. PRECIP CHANCES WILL TAPER OFF FROM SOUTH TO NORTH AS THE PARENT SHORTWAVE LIFTS INTO CANADA THURSDAY MORNING. DRY CONDITIONS ARE THEN EXPECTED OVER MOST OF THE CWA (SANS NORTHWESTERN NORTH DAKOTA) BY THURSDAY AFTERNOON. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 335 PM CDT WED SEP 25 2013 THE HIGHLIGHTS OF THE EXTENDED PERIOD ARE RAIN AND WIND THURSDAY THROUGH FRIDAY NIGHT. WIDESPREAD RAINFALL UP TO ONE INCH IS LIKELY FOR SOME PARTS OF NORTH DAKOTA THURSDAY MORNING THROUGH FRIDAY NIGHT. GUSTY WINDS AROUND 35 MPH ARE LIKELY ACROSS MUCH OF WESTERN AND CENTRAL NORTH DAKOTA THURSDAY AFTERNOON. STRONG FORCING AND AMPLE MOISTURE WILL LIKELY BE IN PLACE ACROSS THE REGION THURSDAY THROUGH FRIDAY THANKS TO A STRONG UPPER LEVEL JET...DEEP LONGWAVE TROUGH...AND ISALLOBARIC FORCING ALONG THE INVERTED TROUGH. SEVERAL UPPER LEVEL SHORTWAVE TROUGHS SHOULD EJECT OUT OF THE MAIN LONGWAVE TROUGH TO THE WEST. IT APPEARS ONE SHOULD ARRIVE ON OUR DOORSTEP WEDNESDAY NIGHT...THURSDAY NIGHT AND FRIDAY NIGHT. THIS WOULD TEND TO FAVOR PRECIPITATION ARRIVING IN WAVES WITH BREAKS IN BETWEEN. THERE IS SOME UNCERTAINTY BETWEEN THE MAJOR MODELS AS TO EXACT LOCATION OF THE HEAVIEST RAIN AND TIMING OF THE MAIN COLD FRONT PUSH OUT OF THE REGION. THE 12 UTC GFS AND 12 UTC ECMWF APPEAR TO BE SLIGHTLY SLOWER WITH THE EXIT OF THE SYSTEM AND THEREFORE PRODUCE MORE PRECIP OVER WESTERN AND CENTRAL NORTH DAKOTA. THE 12 UTC GEM/NAM AND 09Z SREF HAVE THE BULK OF THE RAIN FALLING ACROSS EASTERN NORTH DAKOTA WITH THE FRONT PUSHING THROUGH EARLIER FRIDAY. THEREFORE...FOR THIS FORECAST ISSUANCE WENT WITH A BLEND OF THE MAJOR MODELS WITH A SLIGHT FAVOR TOWARD THE EASTWARD (FASTER) MODELS AS THE GFS HAS SHOWN A SLIGHT EASTWARD TREND OVER THE PAST FEW RUNS. DUE TO UNCERTAINTY DID NOT INCREASE CHANCES OF PRECIPITATION FOR THURSDAY OR FRIDAY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1206 AM CDT THU SEP 26 2013 SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE OVERNIGHT FOR ALL AERODROMES EXCEPT KJMS. A COLD FRONT JUST WEST OF KMOT AND KBIS WILL SLOWLY MOVE EAST THURSDAY. A PERIOD OF MVFR CIGS TOWARD 10Z AND 12Z THURSDAY ARE FORECAST TO DEVELOP...WITH KJMS BARELY REMAINING IN THE LOW VFR RANGE. GUSTY SOUTHWEST TO WESTERLY WINDS ARE FORECAST THURSDAY...BETWEEN 20KT AND 32KT. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...KS SHORT TERM...TM LONG TERM...AJ AVIATION...KS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
321 AM CDT THU SEP 26 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 321 AM CDT THU SEP 26 2013 AT 3 AM...A 1020 MB HIGH WAS CENTERED NORTH OF LAKE HURON. EASTERLY WINDS ON THE SOUTHERN PERIPHERY OF THIS HIGH CONTINUES TO BRING LOWER AND MID 40 DEW POINTS INTO CENTRAL AND NORTH-CENTRAL WISCONSIN. THE COMBINATION OF THESE DEW POINTS ALONG WITH CLEAR SKIES AND LIGHT WINDS HAS ALLOWED TEMPERATURES THESE AREAS TO COOL INTO THE LOWER AND MID 40S. WITH THESE TEMPERATURES COOLER THAN THE WATER TEMPERATURES...STEAM FOG HAS DEVELOPED IN THIS AREA. THERE ARE EVEN A FEW REPORTS OF DENSE FOG AT VOLK FIELD AND WAUTOMA. WITH BUFKIT RAP SOUNDINGS CONTINUING TO SHOW THAT THE WINDS BELOW 900 MB WILL BE INCREASING TO AROUND 10 KNOTS BY SUNRISE...NOT EXPECTING THIS FOG TO BECOME AS WIDESPREAD AS WEDNESDAY MORNING. HOWEVER WITH THIS SAID...WE ARE STILL CONSIDERING A DENSE FOG ADVISORY IN ADAMS AND JUNEAU COUNTIES IN CENTRAL WISCONSIN. SHERIFF DEPARTMENTS IN BOTH OF THESE COUNTIES ARE REPORTING PATCHY DENSE FOG. THE RAP WOULD SUGGEST THAT THE LOW LEVEL MOISTURE WILL INCREASE THROUGH THE REMAINDER OF THIS MORNING. MEANWHILE NAM/WRF SHOWS THAT THIS LOW LEVEL MOISTURE MIXES OUT BY 26.14Z. FOR TODAY...HIGH PRESSURE WILL PROVIDE ANOTHER SUNNY DAY ACROSS THE UPPER MISSISSIPPI RIVER VALLEY. AS DIURNAL HEATING MIXES OUT THE NOCTURNAL INVERSION THIS MORNING...EXPECT WIND GUSTS TO CLIMB INTO THE 15 TO 30 MPH BETWEEN 10 AM AND NOON...AND THEN CONTINUE THROUGH THE AFTERNOON. LIKE YESTERDAY...IT LOOKS LIKE THE AREA WILL MIX TO AROUND 875 MB. THIS WILL YIELD TEMPERATURES IN THE LOWER TO MID 70S NORTH OF INTERSTATE 94...AND FROM THE MID 70S TO AROUND 80 ACROSS THE REMAINDER OF THE AREA. FOR TONIGHT...THE CENTER OF SURFACE HIGH WILL DRIFT EAST INTO QUEBEC. THIS WILL ALLOW THE COLD FRONT...CURRENTLY LOCATED OVER THE CENTRAL DAKOTAS...TO MOVE EAST INTO WESTERN AND NORTHERN MINNESOTA. AS THIS OCCURS...SOME MOISTURE BETWEEN 600 AND 700 MB WILL MOVE EAST INTO THE FORECAST AFTER AFTER 27.08Z. THE NOCTURNAL INVERSION WILL QUICKLY THIS EVENING WITH THE LOSS OF DIURNAL HEATING. AS THIS OCCURS...THE WIND GUSTS WILL DIMINISH. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 321 AM CDT THU SEP 26 2013 FROM FRIDAY AFTERNOON INTO FRIDAY NIGHT...THE 26.00Z MODELS ARE IN VERY GOOD AGREEMENT THAT THE COLD FRONT WILL MOVE EAST INTO WESTERN MINNESOTA DURING THE AFTERNOON AND EVENING...AND THEN IT STALLS ITS EASTWARD PROGRESS ON FRIDAY NIGHT AS A SURFACE LOW MOVES NORTH ALONG IT. WITH SOUNDINGS CONTINUING TO SHOW CAPPING BETWEEN 800 AND 650 MBS AND DRY AIR AHEAD OF THIS FRONT...NOT EXPECTING ANY PRECIPITATION TO OCCUR AHEAD OF IT....THUS KEPT THE FORECAST DRY. FROM SATURDAY INTO SATURDAY EVENING...THE MODELS CONTINUE TO SHOW THAT THE SURFACE COLD FRONT AND SHORT WAVE TROUGH WILL MOVE QUICKLY EAST ACROSS THE AREA. LIKE THE PAST DAYS...THE 0-6 KM SHEAR REMAINS ABOVE 40 KNOTS ALONG AND IN THE WAKE OF THE FRONT. HOWEVER THE ML CAPES REMAIN GENERALLY LESS THAN 100 J/KG...SO STILL NOT CONCERNED THAT THE AREA WILL EXPERIENCE ANY SEVERE WEATHER. JUST TOO LITTLE INSTABILITY FOR THE AMOUNT SHEAR. OVERALL...ACTUALLY THINK THAT OUR BEST CHANCE OF THUNDER WILL ACTUALLY COME FROM MORE SLANTWISE THAN UPRIGHT CONVECTION. DUE TO THE CONSISTENCY OF THE TIMING WITH THE FRONTOGENESIS...RAISED THE PRECIPITATION CHANCES INTO THE 75 TO 84 PERCENT RANGE. THINKING WITH THE SPEED OF THE SHORT WAVE TROUGH AND FRONT THAT THE PRECIPITATION WILL LIKELY ONLY LAST 2 TO 4 HOURS IN ANY LOCATION. FROM TUESDAY INTO WEDNESDAY...THE MODELS ARE NOW SHOWING THAT THE SHORT WAVE WILL PASS WELL NORTH OF THE AREA. DUE TO THIS...THE PRECIPITATION CHANCES WERE REMOVED FROM THE FORECAST. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1100 PM CDT WED SEP 25 2013 THE 500 MB RIDGE AXIS HANGS ACROSS THE REGION OVERNIGHT...WHILE THE SFC HIGH HOVERS OVER THE GREAT LAKES. WINDS HAVEN/T DECOUPLED IN THE VALLEY AT KLSE...ALTHOUGH STILL ANTICIPATE THEY WILL LIGHTEN UP BY A FEW MORE KTS. THAT SAID...KRST REMAINS IN THE 8-10 KT RANGE WHILE WINDS INCREASE SEVERAL KNOTS MORE BY 200 FT. THIS NEAR SFC STIRRING WILL MAKE IT DIFFICULT FOR RIVER VALLEY FOG TO SPREAD ACROSS KLSE...IF IT WOULD DEVELOP. KLSE T/TD SPREAD AT 03Z WAS 8 F WITH 7 KT WINDS...NOT FAVORABLE FOR SUB 1/2SM. IF WINDS KEEP UP...MVFR BR IS ALSO UNLIKELY. FOG DID NOT FORM IN THE PRESSURE GRADIENT THIS MORNING...AND WITH THAT GRADIENT SHIFTED OVER KRST/KLSE...WILL STAY WITH THE NON-FOG FORECAST FOR EARLY THU MORNING. THE HIGH WILL CONTINUE TO EASE EAST THURSDAY...WITH A TIGHTENING PRESSURE GRADIENT ACROSS THE REGION. WINDS WILL BE ON THE INCREASE FROM THE SOUTH/SOUTHEAST AS A RESULT...GUSTY FOR THE LATE MORNING/AFTERNOON HOURS. ASIDE FROM ANY POTENTIAL FOR FOG OVERNIGHT...VFR CONDITIONS WILL PERSIST. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...BOYNE LONG TERM...BOYNE AVIATION.....RIECK
AREA FORECAST DISCUSSION
NWS MIAMI FL
852 AM EDT THU SEP 26 2013 .UPDATE... SATELLITE AND OBSERVATIONS FROM THIS MORNING SHOWED A BOUNDARY ACROSS NORTH FLORIDA. SCATTERED SHOWERS AND A COUPLE THUNDERSTORMS WERE DEVELOPING ACROSS THE LOCAL GULF WATERS AND MOVING ACROSS COLLIER...HENDRY...AND GLADES COUNTIES IN THE WESTERLY FLOW. THE 12Z SOUNDING SHOWED SOME DRIER AIR ALOFT...WITH PRECIPITABLE WATER VALUES DOWN TO AROUND 1.8 INCHES. WATER VAPOR SHOWED MUCH DRIER MID LEVEL AIR MOVING SOUTHWARD ACROSS THE SOUTHEAST AND INTO NORTH FLORIDA. MODIFYING THE SOUNDING INDICATED THAT THERE WAS A POSSIBILITY OF STRONG TO EVEN ISOLATED SEVERE STORMS THIS AFTERNOON WITH THE MAIN THREAT BEING STRONG/ISOLATED SEVERE DOWNBURST WINDS. THE LATEST HRRR SHOWS A LINE OF SHOWERS AND STORMS DEVELOPING ACROSS THE NORTHERN PORTION OF THE REGION BY MID AFTERNOON AND SLOWLY SLIDING SOUTHEAST. SO STRETCHED THE HIGHER POPS THAT WERE ACROSS THE EAST BACK TO THE WESTERN PORTIONS OF THE REGION AS WELL. DRIER AIR WILL FILTER INTO THE REGION FROM THE NORTH BY THIS EVENING AS A SHORTWAVE DIVES SOUTH AND LOW PRESSURE DEVELOPS OVER THE WESTERN ATLANTIC. THIS WILL DRIVE THE DRIER AIR INTO THE REGION OVERNIGHT TONIGHT INTO THE DAY ON FRIDAY. && .PREV DISCUSSION... /ISSUED 639 AM EDT THU SEP 26 2013/ AVIATION... VFR CONDITIONS THIS MORNING WITH SOME ISOLATED TO SCATTERED SHOWERS MOVING ACROSS THE AREA. LATER TODAY, A SURFACE COLD FRONT, WHICH WILL BE MORE OF JUST A DRY LINE TYPE OF FRONT, WILL BEGIN TO PUSH INTO SOUTH FLORIDA. THIS WILL ALLOW SHOWERS AND THUNDERSTORMS TO DEVELOP THIS AFTERNOON. THE FRONTAL PASSAGE IS A LITTLE TRICKY TO TIME AS IT HAS NOT BEGUN TO MOVE YET. CURRENTLY THINK IT WILL BE LATER IN THE DAY, AFTER 22Z. BEHIND THE FRONT, CONDITIONS QUIET DOWN AND SKIES SHOULD CLEAR. THE ONLY EXCEPTION TO VFR TODAY WILL BE IN ASSOCIATION WITH ANY SHOWERS AND/OR THUNDERSTORMS THAT AFFECT THE TAF SITES, BRINGING CONDITIONS TO MVFR, AND MAYBE EVEN BRIEF IFR. WINDS ARE LIGHT AND VARIABLE THIS MORNING. THEY WILL PICK UP OUT OF THE WEST AROUND 10 KTS. THERE WILL BE A WIND SHIFT WITH THE FRONTAL PASSAGE TO NW BETWEEN 5 AND 10 KTS. THEY SHOULD GO LIGHT AND VARIABLE ONCE AGAIN LATE TONIGHT. PREV DISCUSSION... /ISSUED 417 AM EDT THU SEP 26 2013/ DISCUSSION... QUASI-STATIONARY FRONTAL BOUNDARY CONTINUES TO BE DRAPED ACROSS NORTHERN FLORIDA EARLY THIS MORNING. THIS FRONT IS STILL EXPECTED TO PUSH TO THE SOUTH THROUGH THE DAY AND INTO THE LAKE OKEECHOBEE REGION BY THE LATE AFTERNOON TO EARLY EVENING HOURS...AND FURTHER SOUTH INTO THE MID TO LATE EVENING HOURS. MODEL SOUNDINGS STILL SHOW PRECIPITABLE WATER AMOUNTS AROUND 2 INCHES ACROSS SOUTH FLORIDA PRECEDING THE FRONT. AS A RESULT...SCATTERED SHOWERS AND A FEW THUNDERSTORMS ARE EXPECTED TO DEVELOP ACROSS THE AREA BEGINNING DURING THE LATE MORNING HOURS AND COULD BE ENHANCED BY THE FRONTAL PASSAGE THIS EVENING. CURRENTLY BELIEVE THE BEST COVERAGE OF SHOWERS AND THUNDERSTORMS ASSOCIATED WITH THE FRONT SHOULD BE ALONG THE EASTERN HALF OF THE CWA INCLUDING THE ATLANTIC WATERS WITH SLIGHTLY BETTER CONVERGENCE. THIS IS ALSO DEPICTED FAIRLY WELL BY MODEL REFLECTIVITY. THIS FRONT WILL EXIT THE AREA BY FRIDAY MORNING USHERING IN MUCH DRIER AIR INTO SOUTH FLORIDA UNDER NORTH TO NORTHEAST FLOW. THIS WILL YIELD DEW POINTS IN THE UPPER 60S TO NEAR 70 ACROSS VIRTUALLY THE ENTIRE AREA. BY LATE SATURDAY...CHANCES FOR A FEW DIURNAL SHOWERS AND THUNDERSTORMS WILL RETURN AS MOISTURE WRAPS AROUND A PERSISTENT AREA OF LOW PRESSURE ACROSS THE WESTERN ATLANTIC AND INTO SOUTH FLORIDA. DRIER WEATHER RETURNS SUNDAY PERSISTING INTO NEXT WEEK AS THE AREA OF LOW PRESSURE GETS ABSORBED INTO A BROAD H5 SHORTWAVE AND RETREATS TO THE NORTHEAST. UPPER RIDGING THEN BUILDS IN WITH A RETURN TO A MORE EASTERLY FLOW PATTERN. MARINE... MODERATE WESTERLY WINDS WILL PREVAIL THROUGH THE DAY BEFORE TURNING MORE NORTHERLY AS A COLD FRONT CROSSES THROUGH THE REGION DURING THE LATE AFTERNOON/EARLY EVENING HOURS. SCATTERED SHOWERS AND THUNDERSTORMS WILL ACCOMPANY THE FRONT ACROSS THE REGIONAL WATERS. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 88 77 87 75 / 50 30 20 20 FORT LAUDERDALE 87 79 87 75 / 50 30 20 20 MIAMI 88 78 88 75 / 50 20 20 20 NAPLES 87 77 88 73 / 50 20 20 10 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ DISCUSSION/MARINE/FIRE...84/AK AVIATION/RADAR...55/CWC
AREA FORECAST DISCUSSION...UPDATED
NWS MARQUETTE MI
944 AM EDT THU SEP 26 2013 .UPDATE... ISSUED AT 937 AM EDT THU SEP 26 2013 CHANGES THIS HOUR: WILL EXTEND FOG ANOTHER HOUR GIVEN EARLY MORNING VISIBLE SATELLITE TRENDS WHICH SHOW A /VERY/ SLOW BURNING OFF PROCESS BEGINNING. OTHERWISE...HAVE LOWERED AFTERNOON DEWPOINTS A TAD BASED ON DRY AIRMASS CENTERING ITSELF OVERHEAD THIS AFTERNOON...WITH NO OTHER SIGNIFICANT CHANGES NECESSARY. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 406 AM EDT THU SEP 26 2013 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW A STAGNANT UPR FLOW OVER THE CONUS WITH UPR RDG OVER THE GREAT LKS SANDWICHED BTWN SLOW MOVING CLOSED LO OFF THE CANADIAN MARITIMES AND A DEEPENING TROF OVER THE WRN STATES. SFC HI PRES REMAINS ANCHORED IN QUEBEC... WITH RDG AXIS EXTENDING SWWD INTO THE UPR LKS. ALTHOUGH ABUNDANT MID LVL DRY AIR ABOVE SHARP SUBSIDENCE INVRN NEAR H9 SHOWN ON THE 00Z GRB/APX RAOBS IS BRINGING DRY WX...EFFICIENT NOCTURNAL COOLING HAS ALLOWED FOG TO FORM OVER MAINLY THE SCENTRAL COUNTIES AND THE KEWEENAW WHERE LGT E-SE FLOW ARND SFC HI PRES IS UPSLOPING OFF THE LKS. BUT IN CONTRAST TO LAST NGT...ADVECTION OF VERY DRY NEAR SFC AIRMASS SHOWN ON THE 00Z APX RAOB /PWAT 0.30 INCH/ IS TENDING TO LIMIT THE COVERAGE OF THE THICKER FOG. MAIN FCST CONCERNS IN THE SHORT TERM ARE FOG TRENDS AND TEMPS AS WELL AS THE POTENTIAL FOR MORE FOG FORMATION TNGT. EARLY THIS MRNG/TDAY...MAIN LIMITATION TO WDSPRD DENSE FOG EARLY THIS MRNG WL BE THE ADVECTION OF THE DRIER LLVL AIR SHOWN ON THE 00Z APX RAOB. SHORT TERM MODEL FCSTS SHOW THIS DRIER H95-9 AIR BLO THE SUBSIDENCE INVRN OVERSRREADING UPR MI EARLY THIS MRNG...COUNTERING TO SOME EXTENT THE IMPACT OF NOCTURNAL COOLING UNDER THE MID LVL DRY AIR. WL MAINTAIN A MENTION OF AREAS OF FOG UNTIL 13Z OVER THE SCENTRAL WITH FVRBL UPSLOPE WIND COMPONENT. AWAY FM THIS AREA...EXPECT NOTHING MORE THAN PATCHY FOG. DOWNSLOPE NATURE OF THE LLVL FLOW WL LIKELY KEEP MUCH FOG FM DVLPG NEAR LK SUP AND OVER THE FAR W ARND IWD. ISSUED SPS FOR THE SCENTRAL COUNTIES TO COVER LOCALLY DENSE FOG IN THIS AREA THRU SUNRISE...BUT AN ADVY WL NOT BE NECESSARY. ONCE ANY FOG BURNS OFF SOON AFTER SUNRISE...EXPECT MOSUNNY SKIES. WITH H85 TEMPS FCST UP TO 17C OVER THE W...MAX TEMPS THERE SHOULD TOP OUT IN THE 70S AWAY FM SOME MODERATION ON MAINLY THE E SIDE OF THE KEWEENAW IN LLVL SE FLOW. THIS SE FLOW WL TEND TO LIMIT THE DIURNAL TEMP RISE OVER THE SE COUNTIES. TNGT...THE UPR RDG AXIS IS FCST TO DRIFT ONLY SLOWLY TO THE E...WITH SFC HI OVER QUEBEC DRIFTING S INTO NEW ENGLAND. WITH FALLING MSLP IN THE PLAINS ASSOCIATED WITH SHRTWV LIFTING OUT OF THE WRN TROF...THE PRES GRADIENT/SLY FLOW IS PROGGED TO SHARPEN OVER MAINLY WRN UPR MI. THIS INCRSG S WIND IN CONCERT WITH FCST INCRSG PWAT WL RESTRICT THE DIURNAL TEMP FALL IN THIS AREA...SO TENDED TOWARD THE WARM SIDE OF GUIDANCE FOR MIN TEMPS OVER THE FAR W FM IWD INTO THE KEWEENAW. A FLATTER PRES GRADIENT/PWAT FCST AOB 0.50 INCH CLOSER TO THE SFC HI TO THE E WL SUPPORT LOWER TEMPS OVER THE INTERIOR E HALF...AND FCST LO TEMPS CLOSER TO THE LO END OF GUIDANCE IN THIS AREA. BUT SOMEWHAT STRONGER H925 WINDS UP TO 20KTS FCST IN THIS AREA WL LIKELY KEEP THE LOWS A BIT HIER THAN OBSVD THIS MRNG. WITH THE S WIND OFF LK MI... EXPECT MORE FOG TO FORM IN THIS AREA. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 406 AM EDT THU SEP 26 2013 FRIDAY WILL BE THE LAST COMPLETELY DRY DAY ACROSS THE CWA AS THE HIGH PRESSURE RIDGE THAT HAS BEEN INFLUENCING OUR WEATHER SLIDES SOUTHEAST INTO THE ATLANTIC STATES. AT THE SAME TIME...THE UPPER TROUGH CURRENTLY OVER THE WESTERN CONUS WILL EJECT OUT OF THE ROCKIES AND INTO THE CENTRAL AND NORTHERN PLAINS. A SHORTWAVE EXITING THIS UPPER TROUGH WILL MOVE NORTHEAST THROUGH THE CANADIAN PRAIRIES WITH AN ASSOCIATED SURFACE LOW THAT LEAVE AN ELONGATED SURFACE TROUGH STRETCHING SOUTH THROUGH MINNESOTA AND INTO THE CENTRAL PLAINS. SINCE THAT WILL BE THE MAIN FOCUS OF THE PRECIPITATION ON FRIDAY AND THE AREA STILL UNDER THE DRY AIR OF THE HIGH...SHOULD SEE ANOTHER MOSTLY SUNNY DAY ACROSS THE CWA. LATE IN THE AFTERNOON...COULD SEE SOME MID-HIGH CLOUDS AFFECTING WESTERN UPPER MICHIGAN. WITH THE SUNSHINE...SHOULD SEE ANOTHER DAY OF ABOVE NORMAL HIGHS WITH TEMPERATURES IN THE UPPER 60S TO MIDDLE 70S. IT SHOULD BE A LITTLE BREEZY ON FRIDAY DUE TO THE INCREASING PRESSURE GRADIENT BETWEEN THE HIGH AND THE APPROACHING TROUGH...ESPECIALLY OVER THE WEST WHERE THERE COULD BE GUSTS TO 25-30MPH. EXPECT BREEZY CONDITIONS TO CONTINUE AT TIMES FRIDAY NIGHT INTO SATURDAY UNTIL THE FRONT MOVES THROUGH. THIS DRY AIR WILL REMAIN THROUGH FRIDAY NIGHT AND INTO SATURDAY MORNING...WITH ONLY A FEW SHOWERS BRUSHING FAR WESTERN LAKE SUPERIOR DURING THAT TIME. THEN...AS THE UPPER TROUGH EJECTS OUT OF THE FOUR CORNERS REGION FRIDAY NIGHT...IT PULLS THE ENTIRE UPPER TROUGH WITH IT AND THROUGH THE UPPER GREAT LAKES REGION THROUGH SUNDAY. IN ADDITION...A SECONDARY LOW WILL DEVELOP ALONG THE TROUGH NEAR WESTERN LAKE SUPERIOR AND THE MN ARROWHEAD AS THE RIGHT REAR OF THE UPPER JET SLIDES NORTHEAST THROUGH THE AREA. THIS WILL ALLOW A LINE OF SHOWERS ORIENTATED NORTH-SOUTH ALONG AND BEHIND THE TROUGH TO MOVE EAST-NORTHEAST ACROSS UPPER MICHIGAN. AS HAS BEEN THE CASE OVER THE LAST SEVERAL NIGHT...THE GFS REMAINS THE FASTEST WITH THE ARRIVAL OF THE TROUGH/SHOWERS...WHILE THE GEM/ECMWF ARE MORE CONSISTENT WITH THE SLOWER ARRIVAL. THE NAM ALSO FOLLOWS ALONG WITH THE FASTER ARRIVAL SHOWN IN THE GFS. SINCE THERE IS AN EVEN SPLIT IN ARRIVAL TIMES AND ONLY 50-75MI SPREAD...WILL SPLIT THE DIFFERENCE AT THIS POINT AND HAVE THE WESTERN THIRD/HALF OF UPPER MICHIGAN SEEING RAIN BY SUNSET AND THEN IT SPREADING ACROSS THE REST OF THE CWA SATURDAY EVENING. WITH THE DIFFERENCES IN SPEED...ALSO FOLLOWED THE SIMILAR IDEA FOR THE BACK SIDE OF THE RAIN OVERNIGHT SATURDAY. STILL APPEARS LIKE A DECENT OPPORTUNITY FOR A QUARTER INCH OF RAIN OVER MUCH OF THE CWA...ALTHOUGH IT WILL LIKELY FALL IN A 2-3HR PERIOD. FINALLY...THUNDER POTENTIAL STILL LOOKS TO BE VERY LIMITED...ESPECIALLY WITH MUCH OF THE RAIN EXPECTED TO BE POST-FRONTAL. THERE ARE A COUPLE SMALL POCKETS OF 700-500MB LAPSE RATES APPROACHING 6.5C/KM AHEAD OF THE FRONT AND SIMILAR POCKETS OF MUCAPE NEAR 250 J/KG. IF A RUMBLE OF THUNDER OCCURS...BELIEVE IT WOULD BE IN THE WESTERN U.P. IN THE AFTERNOON. BUT...SINCE COVERAGE SHOULD BE VERY ISOLATED...OPTED TO REMOVE THE SLIGHT CHANCE OF THUNDER. WEAK UPPER RIDGE WILL QUICKLY BUILD IN ON SUNDAY AFTERNOON AND REMAIN INTO MONDAY. THIS WILL LEAD TO ANOTHER DRY PERIOD OF WEATHER. THERE MAY BE A SOME POST-FRONTAL CLOUDS SUNDAY AFTERNOON AS A POCKET OF COOLER TEMPERATURES ALOFT MOVE THROUGH. ECMWF/GEM SEEM TO LIKE THAT IDEA...WHILE GFS KEEPS THINGS CLEAR. SINCE THAT MOISTURE AND COOLER AIR WILL BE QUICKLY PULLING OUT ON SUNDAY...WITH FOLLOW THE GENERAL IDEA OF DECREASING CLOUDS ON SUNDAY. HIGHS WILL BE COOLER ON SUNDAY WITH THAT COLD POCKET OF AIR...BUT STILL THINK THEY WILL END UP IN THE LOWER-MID 60S IN MOST LOCATIONS (WHICH IS NORMAL FOR THIS TIME OF YEAR). TEMPERATURES SHOULD WARM BACK ABOVE NORMAL ON MONDAY WITH HIGHS IN THE UPPER 60S AND LOWER 70S...AS 850MB TEMPERATURES PUSH BACK INTO THE LOWER TEENS. CONUS LOOKS TO COME UNDER ZONAL FLOW FOR TUESDAY AND PART OF WEDNESDAY...AS THE UPPER JET RUNS WEST-EAST ACROSS THE NORTHERN ROCKIES. THIS SHOULD KEEP THE MAIN SYNOPTIC FEATURES LOCKED IN CANADA AND POSSIBLY JUST BRUSHING THE AREA AT TIMES MONDAY NIGHT THROUGH TUESDAY NIGHT. THIS WILL ALSO KEEP THE AREA UNDER ABOVE && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 725 AM EDT THU SEP 26 2013 LINGERING FOG/IFR TO VLIFR CONDITIONS WL GIVE WAY TO VFR CONDITIONS BY MID MRNG WITH THE ONSET OF DAYTIME HEATING THAT MIXES OUT THE FOG. THEN VFR WX WL PREVAIL AT ALL 3 TAF SITES THRU AT LEAST 06Z TNGT. A STRONGER S WIND ABOVE RADIATION INVRN TNGT THAT WL CAUSE LLWS AT IWD SHOULD PREVENT MORE FOG FORMATION AT IWD AND CMX. BUT AT SAW...UPSLOPE NATURE OF THE S WIND OFF LK MI AND SOMEWHAT WEAKER FLOW THAT WL ALLOW MORE EFFICIENT RADIATIONAL COOLING WL BE SUFFICIENT FOR A BETTER CHC OF RADIATION FOG AT THAT LOCATION. IF THE WINDS ARE LIGHTER THAN EXPECTED AT SAW...IFR CONDITIONS MIGHT BE && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 406 AM EDT THU SEP 26 2013 HIGH PRESSURE OVER WESTERN QUEBEC WILL CONTINUE TO DOMINATE THE WEATHER FOR TODAY...ALTHOUGH IT WILL BEGIN TO SLIDE SOUTHEAST TONIGHT. BEFORE THIS OCCURS...THERE IS AN AREA OF FOG (LOCALLY DENSE) OVER THE WESTERN LAKE EARLY THIS MORNING AND EXPECT THAT TO DIMINISH THIS MORNING AS DRIER AIR SLIDES IN FROM THE SOUTHEAST. MEANWHILE...A LOW PRESSURE SYSTEM MOVING NORTHEAST OUT OF THE NORTHERN PLAINS TODAY WILL LINGER A TROUGH EASTERN DAKOTAS TONIGHT AND THEN SLOWLY MOVE EAST ACROSS MINNESOTA ON FRIDAY. AS THIS OCCURS...THE PRESSURE GRADIENT AND THUS SOUTHERLY WINDS WILL INCREASE OVER LAKE SUPERIOR ON FRIDAY. THESE STRONGER WINDS...TO 25KTS...WILL CONTINUE FRIDAY NIGHT AND SATURDAY UNTIL THE TROUGH MOVES THROUGH LATE SATURDAY AFTERNOON AND EVENING. BEHIND THE TROUGH...THERE COULD BE A BRIEF PERIOD OF STRONGER WESTERLY WINDS TO 25KTS OVER NORTH CENTRAL LAKE SUPERIOR OVERNIGHT SATURDAY NIGHT INTO EARLY SUNDAY MORNING. WEAK HIGH PRESSURE WILL BUILD IN TO THE UPPER && .MQT WATCHES/WARNINGS/ADVISORIES... MI...NONE. LS...NONE. LM...NONE. && $$ UPDATE...ARNOTT SHORT TERM...KC LONG TERM...SRF AVIATION...KC MARINE...SRF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
725 AM EDT THU SEP 26 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 406 AM EDT THU SEP 26 2013 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW A STAGNANT UPR FLOW OVER THE CONUS WITH UPR RDG OVER THE GREAT LKS SANDWICHED BTWN SLOW MOVING CLOSED LO OFF THE CANADIAN MARITIMES AND A DEEPENING TROF OVER THE WRN STATES. SFC HI PRES REMAINS ANCHORED IN QUEBEC... WITH RDG AXIS EXTENDING SWWD INTO THE UPR LKS. ALTHOUGH ABUNDANT MID LVL DRY AIR ABOVE SHARP SUBSIDENCE INVRN NEAR H9 SHOWN ON THE 00Z GRB/APX RAOBS IS BRINGING DRY WX...EFFICIENT NOCTURNAL COOLING HAS ALLOWED FOG TO FORM OVER MAINLY THE SCENTRAL COUNTIES AND THE KEWEENAW WHERE LGT E-SE FLOW ARND SFC HI PRES IS UPSLOPING OFF THE LKS. BUT IN CONTRAST TO LAST NGT...ADVECTION OF VERY DRY NEAR SFC AIRMASS SHOWN ON THE 00Z APX RAOB /PWAT 0.30 INCH/ IS TENDING TO LIMIT THE COVERAGE OF THE THICKER FOG. MAIN FCST CONCERNS IN THE SHORT TERM ARE FOG TRENDS AND TEMPS AS WELL AS THE POTENTIAL FOR MORE FOG FORMATION TNGT. EARLY THIS MRNG/TDAY...MAIN LIMITATION TO WDSPRD DENSE FOG EARLY THIS MRNG WL BE THE ADVECTION OF THE DRIER LLVL AIR SHOWN ON THE 00Z APX RAOB. SHORT TERM MODEL FCSTS SHOW THIS DRIER H95-9 AIR BLO THE SUBSIDENCE INVRN OVERSRREADING UPR MI EARLY THIS MRNG...COUNTERING TO SOME EXTENT THE IMPACT OF NOCTURNAL COOLING UNDER THE MID LVL DRY AIR. WL MAINTAIN A MENTION OF AREAS OF FOG UNTIL 13Z OVER THE SCENTRAL WITH FVRBL UPSLOPE WIND COMPONENT. AWAY FM THIS AREA...EXPECT NOTHING MORE THAN PATCHY FOG. DOWNSLOPE NATURE OF THE LLVL FLOW WL LIKELY KEEP MUCH FOG FM DVLPG NEAR LK SUP AND OVER THE FAR W ARND IWD. ISSUED SPS FOR THE SCENTRAL COUNTIES TO COVER LOCALLY DENSE FOG IN THIS AREA THRU SUNRISE...BUT AN ADVY WL NOT BE NECESSARY. ONCE ANY FOG BURNS OFF SOON AFTER SUNRISE...EXPECT MOSUNNY SKIES. WITH H85 TEMPS FCST UP TO 17C OVER THE W...MAX TEMPS THERE SHOULD TOP OUT IN THE 70S AWAY FM SOME MODERATION ON MAINLY THE E SIDE OF THE KEWEENAW IN LLVL SE FLOW. THIS SE FLOW WL TEND TO LIMIT THE DIURNAL TEMP RISE OVER THE SE COUNTIES. TNGT...THE UPR RDG AXIS IS FCST TO DRIFT ONLY SLOWLY TO THE E...WITH SFC HI OVER QUEBEC DRIFTING S INTO NEW ENGLAND. WITH FALLING MSLP IN THE PLAINS ASSOCIATED WITH SHRTWV LIFTING OUT OF THE WRN TROF...THE PRES GRADIENT/SLY FLOW IS PROGGED TO SHARPEN OVER MAINLY WRN UPR MI. THIS INCRSG S WIND IN CONCERT WITH FCST INCRSG PWAT WL RESTRICT THE DIURNAL TEMP FALL IN THIS AREA...SO TENDED TOWARD THE WARM SIDE OF GUIDANCE FOR MIN TEMPS OVER THE FAR W FM IWD INTO THE KEWEENAW. A FLATTER PRES GRADIENT/PWAT FCST AOB 0.50 INCH CLOSER TO THE SFC HI TO THE E WL SUPPORT LOWER TEMPS OVER THE INTERIOR E HALF...AND FCST LO TEMPS CLOSER TO THE LO END OF GUIDANCE IN THIS AREA. BUT SOMEWHAT STRONGER H925 WINDS UP TO 20KTS FCST IN THIS AREA WL LIKELY KEEP THE LOWS A BIT HIER THAN OBSVD THIS MRNG. WITH THE S WIND OFF LK MI... EXPECT MORE FOG TO FORM IN THIS AREA. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 406 AM EDT THU SEP 26 2013 FRIDAY WILL BE THE LAST COMPLETELY DRY DAY ACROSS THE CWA AS THE HIGH PRESSURE RIDGE THAT HAS BEEN INFLUENCING OUR WEATHER SLIDES SOUTHEAST INTO THE ATLANTIC STATES. AT THE SAME TIME...THE UPPER TROUGH CURRENTLY OVER THE WESTERN CONUS WILL EJECT OUT OF THE ROCKIES AND INTO THE CENTRAL AND NORTHERN PLAINS. A SHORTWAVE EXITING THIS UPPER TROUGH WILL MOVE NORTHEAST THROUGH THE CANADIAN PRAIRIES WITH AN ASSOCIATED SURFACE LOW THAT LEAVE AN ELONGATED SURFACE TROUGH STRETCHING SOUTH THROUGH MINNESOTA AND INTO THE CENTRAL PLAINS. SINCE THAT WILL BE THE MAIN FOCUS OF THE PRECIPITATION ON FRIDAY AND THE AREA STILL UNDER THE DRY AIR OF THE HIGH...SHOULD SEE ANOTHER MOSTLY SUNNY DAY ACROSS THE CWA. LATE IN THE AFTERNOON...COULD SEE SOME MID-HIGH CLOUDS AFFECTING WESTERN UPPER MICHIGAN. WITH THE SUNSHINE...SHOULD SEE ANOTHER DAY OF ABOVE NORMAL HIGHS WITH TEMPERATURES IN THE UPPER 60S TO MIDDLE 70S. IT SHOULD BE A LITTLE BREEZY ON FRIDAY DUE TO THE INCREASING PRESSURE GRADIENT BETWEEN THE HIGH AND THE APPROACHING TROUGH...ESPECIALLY OVER THE WEST WHERE THERE COULD BE GUSTS TO 25-30MPH. EXPECT BREEZY CONDITIONS TO CONTINUE AT TIMES FRIDAY NIGHT INTO SATURDAY UNTIL THE FRONT MOVES THROUGH. THIS DRY AIR WILL REMAIN THROUGH FRIDAY NIGHT AND INTO SATURDAY MORNING...WITH ONLY A FEW SHOWERS BRUSHING FAR WESTERN LAKE SUPERIOR DURING THAT TIME. THEN...AS THE UPPER TROUGH EJECTS OUT OF THE FOUR CORNERS REGION FRIDAY NIGHT...IT PULLS THE ENTIRE UPPER TROUGH WITH IT AND THROUGH THE UPPER GREAT LAKES REGION THROUGH SUNDAY. IN ADDITION...A SECONDARY LOW WILL DEVELOP ALONG THE TROUGH NEAR WESTERN LAKE SUPERIOR AND THE MN ARROWHEAD AS THE RIGHT REAR OF THE UPPER JET SLIDES NORTHEAST THROUGH THE AREA. THIS WILL ALLOW A LINE OF SHOWERS ORIENTATED NORTH-SOUTH ALONG AND BEHIND THE TROUGH TO MOVE EAST-NORTHEAST ACROSS UPPER MICHIGAN. AS HAS BEEN THE CASE OVER THE LAST SEVERAL NIGHT...THE GFS REMAINS THE FASTEST WITH THE ARRIVAL OF THE TROUGH/SHOWERS...WHILE THE GEM/ECMWF ARE MORE CONSISTENT WITH THE SLOWER ARRIVAL. THE NAM ALSO FOLLOWS ALONG WITH THE FASTER ARRIVAL SHOWN IN THE GFS. SINCE THERE IS AN EVEN SPLIT IN ARRIVAL TIMES AND ONLY 50-75MI SPREAD...WILL SPLIT THE DIFFERENCE AT THIS POINT AND HAVE THE WESTERN THIRD/HALF OF UPPER MICHIGAN SEEING RAIN BY SUNSET AND THEN IT SPREADING ACROSS THE REST OF THE CWA SATURDAY EVENING. WITH THE DIFFERENCES IN SPEED...ALSO FOLLOWED THE SIMILAR IDEA FOR THE BACK SIDE OF THE RAIN OVERNIGHT SATURDAY. STILL APPEARS LIKE A DECENT OPPORTUNITY FOR A QUARTER INCH OF RAIN OVER MUCH OF THE CWA...ALTHOUGH IT WILL LIKELY FALL IN A 2-3HR PERIOD. FINALLY...THUNDER POTENTIAL STILL LOOKS TO BE VERY LIMITED...ESPECIALLY WITH MUCH OF THE RAIN EXPECTED TO BE POST-FRONTAL. THERE ARE A COUPLE SMALL POCKETS OF 700-500MB LAPSE RATES APPROACHING 6.5C/KM AHEAD OF THE FRONT AND SIMILAR POCKETS OF MUCAPE NEAR 250 J/KG. IF A RUMBLE OF THUNDER OCCURS...BELIEVE IT WOULD BE IN THE WESTERN U.P. IN THE AFTERNOON. BUT...SINCE COVERAGE SHOULD BE VERY ISOLATED...OPTED TO REMOVE THE SLIGHT CHANCE OF THUNDER. WEAK UPPER RIDGE WILL QUICKLY BUILD IN ON SUNDAY AFTERNOON AND REMAIN INTO MONDAY. THIS WILL LEAD TO ANOTHER DRY PERIOD OF WEATHER. THERE MAY BE A SOME POST-FRONTAL CLOUDS SUNDAY AFTERNOON AS A POCKET OF COOLER TEMPERATURES ALOFT MOVE THROUGH. ECMWF/GEM SEEM TO LIKE THAT IDEA...WHILE GFS KEEPS THINGS CLEAR. SINCE THAT MOISTURE AND COOLER AIR WILL BE QUICKLY PULLING OUT ON SUNDAY...WITH FOLLOW THE GENERAL IDEA OF DECREASING CLOUDS ON SUNDAY. HIGHS WILL BE COOLER ON SUNDAY WITH THAT COLD POCKET OF AIR...BUT STILL THINK THEY WILL END UP IN THE LOWER-MID 60S IN MOST LOCATIONS (WHICH IS NORMAL FOR THIS TIME OF YEAR). TEMPERATURES SHOULD WARM BACK ABOVE NORMAL ON MONDAY WITH HIGHS IN THE UPPER 60S AND LOWER 70S...AS 850MB TEMPERATURES PUSH BACK INTO THE LOWER TEENS. CONUS LOOKS TO COME UNDER ZONAL FLOW FOR TUESDAY AND PART OF WEDNESDAY...AS THE UPPER JET RUNS WEST-EAST ACROSS THE NORTHERN ROCKIES. THIS SHOULD KEEP THE MAIN SYNOPTIC FEATURES LOCKED IN CANADA AND POSSIBLY JUST BRUSHING THE AREA AT TIMES MONDAY NIGHT THROUGH TUESDAY NIGHT. THIS WILL ALSO KEEP THE AREA UNDER ABOVE NORMAL TEMPERATURES. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 725 AM EDT THU SEP 26 2013 LINGERING FOG/IFR TO VLIFR CONDITIONS WL GIVE WAY TO VFR CONDITIONS BY MID MRNG WITH THE ONSET OF DAYTIME HEATING THAT MIXES OUT THE FOG. THEN VFR WX WL PREVAIL AT ALL 3 TAF SITES THRU AT LEAST 06Z TNGT. A STRONGER S WIND ABOVE RADIATION INVRN TNGT THAT WL CAUSE LLWS AT IWD SHOULD PREVENT MORE FOG FORMATION AT IWD AND CMX. BUT AT SAW...UPSLOPE NATURE OF THE S WIND OFF LK MI AND SOMEWHAT WEAKER FLOW THAT WL ALLOW MORE EFFICIENT RADIATIONAL COOLING WL BE SUFFICIENT FOR A BETTER CHC OF RADIATION FOG AT THAT LOCATION. IF THE WINDS ARE LIGHTER THAN EXPECTED AT SAW...IFR CONDITIONS MIGHT BE PSBL FOR AT LEAST A PORTION OF THE TIME THERE AFT 06Z. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 406 AM EDT THU SEP 26 2013 HIGH PRESSURE OVER WESTERN QUEBEC WILL CONTINUE TO DOMINATE THE WEATHER FOR TODAY...ALTHOUGH IT WILL BEGIN TO SLIDE SOUTHEAST TONIGHT. BEFORE THIS OCCURS...THERE IS AN AREA OF FOG (LOCALLY DENSE) OVER THE WESTERN LAKE EARLY THIS MORNING AND EXPECT THAT TO DIMINISH THIS MORNING AS DRIER AIR SLIDES IN FROM THE SOUTHEAST. MEANWHILE...A LOW PRESSURE SYSTEM MOVING NORTHEAST OUT OF THE NORTHERN PLAINS TODAY WILL LINGER A TROUGH EASTERN DAKOTAS TONIGHT AND THEN SLOWLY MOVE EAST ACROSS MINNESOTA ON FRIDAY. AS THIS OCCURS...THE PRESSURE GRADIENT AND THUS SOUTHERLY WINDS WILL INCREASE OVER LAKE SUPERIOR ON FRIDAY. THESE STRONGER WINDS...TO 25KTS...WILL CONTINUE FRIDAY NIGHT AND SATURDAY UNTIL THE TROUGH MOVES THROUGH LATE SATURDAY AFTERNOON AND EVENING. BEHIND THE TROUGH...THERE COULD BE A BRIEF PERIOD OF STRONGER WESTERLY WINDS TO 25KTS OVER NORTH CENTRAL LAKE SUPERIOR OVERNIGHT SATURDAY NIGHT INTO EARLY SUNDAY MORNING. WEAK HIGH PRESSURE WILL BUILD IN TO THE UPPER GREAT LAKES ON SUNDAY NIGHT AND MONDAY AND LOWER WINDS BELOW 20KTS. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...KC LONG TERM...SRF AVIATION...KC MARINE...SRF
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1007 AM EDT THU SEP 26 2013 .SYNOPSIS... AN UPPER LEVEL WILL MOVE OFF THE CAROLINA COAST THIS AFTERNOON. HIGH PRESSURE WILL BUILD IN FROM THE NORTH ON FRIDAY INTO SUNDAY. && .NEAR TERM /TODAY THROUGH TONIGHT/... AS OF 1000 AM THURSDAY... AN UPPER LEVEL LOW CONTINUES TO ROTATE OVER THE CAROLINAS THIS MORNING AND THE CURRENT RUN OF THE RAP MODELS SHOWS SOME STRONGER POCKETS OF VORTICITY COMING OUT OF SOUTHERN VA AND APPROACHING OUR NORTHERN LOCALES. FURTHER INSPECTION OF SATELLITE AND RADAR DATA SHOWS SOME LIGHT SHOWERS TRYING TO GAIN SOME COVERAGE AS THEY APPROACH ROXBORO OVER THE NEXT COUPLE OF HOURS. RAP MODEL SHOWS THE VORTICITY FIELD WEAKENING SO IT IS UNCLEAR WEATHER OR NOT THESE SHOWERS WILL HOLD TOGETHER BUT AT LEAST SOME SPRINKLES COULD BE POSSIBLE THROUGH EARLY AFTERNOON IN OUR NORTHERN COUNTIES. OTHERWISE THE REST OF THE CWA WILL REMAIN DRY AS DRIER AIR WORKS IN FROM THE SOUTHWEST AND THE LOW GRADUALLY MOVES OFF THE COAST. SOME MID LEVEL CLOUDS CAN BE EXPECTED ACROSS THE AREA THROUGH AT LEAST EARLY AFTERNOON WHICH MAY HELP TO KEEP TEMPERATURES DOWN A BIT. CURRENT OBS SHOW TEMPERATURES IN THE MID 60S TO NEAR 70 AND MAX TEMPS ARE EXPECTED TO TOP OUT IN THE MID 70S TO NEAR 80 IN THE SOUTHWEST WHERE CLEARING WILL OCCUR A LITTLE QUICKER. -ELLIS FOR TONIGHT: ON THE BACK SIDE OF THE DEPARTING MID LEVEL LOW... FLOW ALOFT BECOMES NORTHERLY... WHILE LOWER LEVEL FLOW STAYS A BIT STOUT FROM THE NORTHEAST AS THE MSLP GRADIENT TIGHTENS BETWEEN THE SURFACE LOW OFF THE FL/GA COAST AND THE INCOMING NARROW SURFACE HIGH PRESSURE RIDGE OVER THE EASTERN STATES. THIS FLOW WILL DRAW COOLER CANADIAN AIR INTO CENTRAL NC... WITH THICKNESSES BOTTOMING OUT AROUND 1365 M TOWARD MORNING. FORECAST SOUNDINGS SHOW A LOT OF DRYING THROUGH THE COLUMN AND DEEPLY STABLE AIR... SO EXPECT MOSTLY CLEAR SKIES... WITH A LIGHT NE WIND AS LOW LEVELS DECOUPLE. LOWS 52-56. -GIH && .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... AS OF 315 AM THURSDAY... THE AMPLIFIED MID LEVEL RIDGING FROM LA UP THROUGH MI AND TROUGHING OVER THE NW ATLANTIC WILL KEEP NC BENEATH A MODERATE NORTHERLY FLOW ALOFT... WHILE NEAR THE SURFACE... THE CANADIAN HIGH CENTERED OVER THE ST LAWRENCE VALLEY WILL CONTINUE TO NOSE NARROWLY SSW THROUGH CENTRAL/WRN NC. AS SURFACE PRESSURES REMAIN LOW OFF THE SOUTHEAST COAST... THE SOMEWHAT TIGHT MSLP GRADIENT WILL KEEP A STEADY NORTHEAST FLOW INTO NC... STRONGER OVER THE COASTAL PLAIN TRENDING WEAKER OVER THE TRIAD... MOST NOTABLE FROM LATE MORNING THROUGH AFTERNOON WITH A FEW GUSTS POSSIBLE. THE COLUMN STAYS FAIRLY DRY AND NEUTRAL TO SUBSIDING... HOWEVER MODELS SHOW A WAVE IN THE NORTHERLY STEERING FLOW DROPPING TO THE SOUTH FROM NEW ENGLAND LATE TONIGHT THROUGH THE NORTHEAST AND MIDATLANTIC STATES THROUGH FRIDAY INTO THE EVENING. THIS SHOULD SERVE TO REINFORCE THE COLD AIR ADVECTION AND BRING JUST ENOUGH 925-800 MB MOISTURE INTO THE AREA FOR PARTLY CLOUDY SKIES IN THE AFTERNOON AND POTENTIALLY INTO THE NIGHT TOO... AS THIS MOISTURE REMAINS TRAPPED BENEATH THE SUBSIDENCE INVERSION ALOFT. THICKNESSES ABOUT 15 M BELOW NORMAL WITH SOME SUNSHINE SUPPORTS HIGHS OF 73-78. LOWS 51-56 WITH FAIR SKIES. -GIH && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... AS OF 300 AM THURSDAY... SATURDAY AND SUNDAY: ALL INDICATORS SUGGEST THAT THE CLOSED UPPER LEVEL LOW OFF THE MID-ATLANTIC COAST WILL REMAIN OFFSHORE AND PROVE OF LITTLE CONSEQUENCE(AT LEAST OUTSIDE OF MARINE IMPACTS)...HELD AT BAY BY A HIGH-AMPLITUDE-LOW WAVELENGTH UPPER RIDGE AXIS BUILDING EASTWARD INTO THE CENTRAL/SOUTHERN APPALACHIANS. BETWEEN THESE TWO FEATURES...A COOL NORTHEASTERLY WIND WILL PREVAIL THROUGH THE WEEKEND...ANCHORED IN THE LOW-LEVELS BY A ~1025MB SURFACE HIGH EXTENDING DOWN THE MID-ATLANTIC SEABOARD. DRY AND SEASONABLY COOL WITH LOW-LEVEL THICKNESSES A GOOD 15-20M BELOW NORMAL SATURDAY AND SUNDAY MORNING. HIGHS 73 TO 78...WITH SUNDAY BEFORE THE WARMEST DAY OF THE TWO. LOWS IN THE LOWER TO MID 50S. MID/UPPER LEVEL SHORTWAVE TROUGH OVER THE ROCKIES WILL LIFT NORTHEASTWARD INTO THE UPPER GREAT LAKES AND SOUTHEAST CANADA THROUGH THE WEEKEND. AS THE BETTER SUPPORT ALOFT HEADS NORTH OF THE BORDER...AN ALREADY SCARCE PRECIP SHIELD ACCOMPANYING THE DISSIPATING COLD FRONT WILL LIKELY DRY OUT COMPLETELY ACROSS THE MID-ATLANTIC STATES ON MONDAY...WITH SERIOUS DOUBTS IF THE FRONT WILL EVER MAKE THIS FAR SOUTH. WILL LEAVE FORECAST DRY FOR NOW... BUT SOME SMALL/ISOLATED CHANCES MAY NEED TO BE ADDED AT A LATER TIME AS MODELS INDICATE THE POTENTIAL FOR SOME WEAK SOUTHERN STREAM ENERGY TO MOVE THROUGH THE SOUTHEAST US TUESDAY AND INTO WEDNESDAY. MEANWHILE...TEMPERATURES WILL STEADILY MODERATE THROUGH THE WEEK WITH LOW-LEVEL THICKNESSES CLIMBING A GOOD 20 TO 25 METERS ABOVE NORMAL BY MID-WEEK. HIGHS IN THE UPPER 70S TO MID LOWER 80S. LOWS IN THE MID 50S TO LOWER 60S. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... AS OF 655 AM THURSDAY... VSBYS HAVE VARIED BETWEEN MVFR AND VFR FOR MUCH OF THE NIGHT ACROSS CENTRAL NC TAF SITES... HOWEVER BRIEF PERIODS OF IFR TO LIFR CONDITIONS OCCURRED AT RWI AND GSO... WHERE SKIES BRIEFLY BECAME MOSTLY CLEAR... ALLOWING DENSE FOG TO FORM QUICKLY IN THE DAMP AND LIGHT WIND ENVIRONMENT. WITH THE ONSET OF HEATING AS THE SUN IS RISING... THE ISOLATED PATCHES OF FOG SHOULD START TO MIX OUT... BUT THE RISK OF SUB-VFR VSBYS WILL REMAIN POSSIBLE THROUGH ABOUT 13Z. OTHERWISE... WE`LL CONTINUE TO SEE CONSIDERABLE MID CLOUDS AS A MID LEVEL LOW PRESSURE AREA MOVES OVER THE REGION... ALTHOUGH MOST BASES WILL BE ABOVE 7000 FT AGL. AREAS OF LIGHT RAIN MAY PASS NEAR RWI THROUGH 15Z. ONCE THE STORM SYSTEM ALOFT SHIFTS EASTWARD OFF THE CAROLINA COAST TODAY... EXPECT INCREASING SUNSHINE THROUGH THE DAY AS MID LEVEL CLOUDS SLOWLY BREAK UP AND EXIT THE REGION... WHILE SURFACE HIGH PRESSURE BEGINS TO NOSE IN FROM THE NORTH. VFR CONDITIONS WILL HOLD WITH MOSTLY CLEAR SKIES AFTER 21Z... ALTHOUGH SHALLOW BANKS OF FOG MAY START TO FORM AT RWI 06Z-08Z. SURFACE WINDS WILL BE FROM THE NNE OR NORTHEAST AT SPEEDS OF 5-10 KTS DROPPING TO UNDER 6 KTS BY SUNSET. LOOKING BEYOND 12Z FRIDAY MORNING... SHALLOW FOG BANKS MAY BRING BRIEF IFR CONDITIONS AT RWI THROUGH SUNRISE. OTHERWISE... HIGH CONFIDENCE IN VFR CONDITIONS DOMINATING THROUGH MONDAY AS A RIDGE OF HIGH PRESSURE HOLDS OVER NC. BRIEF SHALLOW SUB-VFR GROUND FOG MAY OCCUR 08Z-12Z EACH MORNING... PRIMARILY AT RWI. WINDS FROM THE NORTHEAST ARE EXPECTED EACH AFTERNOON FRIDAY THROUGH SUNDAY... NEAR 10 KTS AT INT/GSO AND A LITTLE STRONGER -- NEAR 15 KTS -- AT RDU/RWI/FAY... WITH A TIGHT GRADIENT BETWEEN THE HIGH PRESSURE RIDGE AND OFFSHORE LOW PRESSURE. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...ELLIS/HARTFIELD SHORT TERM...HARTFIELD LONG TERM...CBL AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS BISMARCK ND
949 AM CDT THU SEP 26 2013 .UPDATE... ISSUED AT 949 AM CDT THU SEP 26 2013 SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WILL CONTINUE TO LIFT NORTH OUT OF NORTH CENTRAL NORTH DAKOTA THIS MORNING. NONE OF THIS ACTIVITY SHOULD BE SEVERE. ALL THUNDERSTORM ACTIVITY WILL BE OUT OF THE CWA BY THIS AFTERNOON. HIGH PRESSURE BUILDING INTO WESTERN NORTH DAKOTA AND LOW PRESSURE LIFTING INTO MANITOBA WILL GENERATE WINDY CONDITIONS ACROSS WESTERN AND NORTH CENTRAL NORTH DAKOTA THIS AFTERNOON. THE LATEST MODEL PROGS HAVE BACKED OFF ON THE SUSTAINED WIND SPEED FORECAST THIS AFTERNOON. HOWEVER...STILL THINK MARGINAL WIND ADVISORY CONDITIONS WILL BE ACHIEVED IN SOME SPOTS. THEREFORE...MAINTAINED THE CURRENT TEMPORAL AND AREAL RESOLUTION OF THE WIND ADVISORY THIS AFTERNOON. THE REMAINING FORECAST ELEMENTS ARE ON TRACK. THE UPDATED PRODUCTS HAVE BEEN SENT. UPDATE ISSUED AT 651 AM CDT THU SEP 26 2013 LOW PRESSURE SITUATED OVER CENTRAL NORTH DAKOTA WITH SCATTERED SHOWERS AND THUNDERSTORMS LIFTING FROM EAST CENTRAL INTO NORTHEAST NORTH DAKOTA...AND SHOWERS EXTENDING BACK INTO CENTRAL NORTH DAKOTA JUST AHEAD OF THE LOW. COLD NORTHERLY FLOW HAS MOVED INTO WESTERN NORTH DAKOTA WITH IFR CLOUDINESS SPREADING EAST ACROSS WESTERN NORTH DAKOTA. UPDATED WEATHER POPS TO MATCH WITH LATEST RADAR IMAGERY...AND EXTRAPOLATING NORTHEAST THROUGH THE MORNING. LIMITED MENTION OF THUNDER TO THE EAST CENTRAL AND FAR NORTH CENTRAL. INCREASED SKY COVER OVER THE WEST THROUGH THE MORNING TO ACCOUNT FOR THE LOW STRATUS. EXPECT THIS TO DISSIPATE BY LATE MORNING AND AFTERNOON WITH STRONG SUBSIDENCE MOVING INTO WESTERN NORTH DAKOTA. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 249 AM CDT THU SEP 26 2013 MAIN CONCERN TODAY WILL BE THUNDERSTORMS EARLY THIS MORNING FOLLOWED BY A WIND ADVISORY SOUTHWEST THROUGH NORTH CENTRAL. HAVE UTILIZED A BLEND OF ALL MODELS...BUT SPECIFICALLY THE HRRR FOR AREAL COVERAGE OF PRECIPITATION THIS MORNING AND NAM/GFS FOR THE WIND ADVISORY. THE LATEST WATER VAPOR IMAGERY ALONG WITH SPC MESOSCALE ANALYSIS CONTINUES TO SHOW THE H3 JET STREAK WORKING ITS WAY THROUGH WYOMING AND INTO SOUTH DAKOTA. UPPER DIVERGENCE FIELD ASSOCIATED WITH THE LEFT EXIT REGION CENTERED OVER CENTRAL/NORTHERN NORTH DAKOTA AS ISOLATED THUNDERSTORMS CONTINUE TO ESCALATE UPWARDS. SURFACE LOW PRESSURE IN SOUTHERN SOUTH DAKOTA WILL BEGIN TO MOVE NORTH ALONG A COLD FRONT WHICH IS NOW LOCATED FROM NEAR OXBOW SASKATCHEWAN...SOUTH TO MINOT AND INTO LEMMON SOUTH DAKOTA. AS THE JET STREAK AND UPPER DIVERGENCE FIELD SHIFT FURTHER NORTH THROUGH THE MORNING...THE SURFACE LOW WILL DEEPEN AS IT ENTERS SOUTHERN SASKATCHEWAN THIS AFTERNOON. A TIGHT PRESSURE GRADIENT WILL ENSUE...RESULTING IN A MARGINAL WIND ADVISORY EVENT. WITH SUSTAINED WINDS VERY NEAR 30 MPH AND GUSTS TO 40 MPH OVER A FAIRLY LARGE AREA...DECIDED TO ISSUE A WIND ADVISORY FOR THE SOUTHWEST AND NORTH CENTRAL ZONES. WINDS WILL INCREASE FIRST ACROSS THE SOUTHWEST LATE THURSDAY MORNING...THEN TRANSLATE INTO NORTH CENTRAL BEGINNING IN THE EARLY AFTERNOON. WINDS WILL THEN DIMINISH FROM SOUTH TO NORTH THURSDAY EVENING. AS FAR AS SHOWERS AND THUNDERSTORMS...THERE WILL BE A DIMINISHING EFFECT AS THE SURFACE LOW MOVES FROM SOUTH TO NORTH TODAY. MAIN INSTABILITY WASHES OUT BY 18Z IN THE NORTH AND HAVE ENDED THE THUNDERSTORM THREAT IN THE GRIDDED FORECAST AT THAT TIME. DRY WEATHER COMMENCES CENTRAL AND SOUTH TODAY INTO EARLY TONIGHT. THE NEXT ROUND OF SHOWERS BEGINS IN THE SOUTHWEST EARLY TONIGHT AND GRADUALLY EXPANDS NORTHEAST OVERNIGHT. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 249 AM CDT THU SEP 26 2013 THE MAIN FORECAST ISSUE IN THE LONG TERM PERIOD WILL BE PRECIPITATION CHANCES AND PLACEMENT FRIDAY THROUGH SATURDAY MORNING. THERE IS STILL SOME DISAGREEMENT AMONG THE DETERMINISTIC MODELS WITH PRECIPITATION ACROSS NORTH DAKOTA ON FRIDAY. HOWEVER...THERE IS MUCH BETTER AGREEMENT FRIDAY NIGHT INTO SATURDAY MORNING. WE BEGIN THE LONG TERM PERIOD ON FRIDAY WITH AN UPPER LEVEL TROUGH OVER THE NORTHERN AND CENTRAL ROCKIES. SHEARED VORTICITY ALONG THE LEADING EDGE OF THE TROUGH EXTENDS ACROSS EASTERN MONTANA AND WESTERN NORTH DAKOTA. THE ECMWF IS SHOWING A BROAD AREA OF LIGHT TO MODERATE RAIN LIFTING SOUTHWEST TO NORTHEAST ACROSS THE FORECAST AREA...WHILE THE GFS/GEM CONTINUE TO INDICATE TWO SEPARATE AREAS OF PRECIPITATION...ONE OVER THE WESTERN DAKOTAS ASSOCIATED WITH THE UPPER LEVEL TROUGH...AND ANOTHER OVER EASTERN NORTH DAKOTA ASSOCIATED WITH THE SURFACE SYSTEM...AND A DRY SLOT OVER CENTRAL NORTH DAKOTA. DUE TO CONTINUED DIFFERENCES...WILL SETTLE ON A BROAD BRUSH OF CHANCE TO HIGH CHANCE POPS UNTIL THERE IS BETTER MODEL AGREEMENT. EITHER WAY IT WILL BE QUITE COOL AND CLOUDY WITH SCATTERED LIGHT RAIN AND HIGHS MAINLY IN THE 50S. THERE IS BETTER MODEL AGREEMENT AS THE KICKER SHORTWAVE ROUNDS THE BASE OF THE UPPER TROUGH AND LIFTS INTO THE CENTRAL PLAINS FRIDAY NIGHT. STRONG 2D FRONTOGENESIS SETS UP OVER THE EASTERN DAKOTAS FRIDAY NIGHT AS THE SURFACE LOW TRACKS FROM THE CENTRAL PLAINS INTO NORTHERN MINNESOTA BY SATURDAY MORNING. THIS RESULTS IN AN ENHANCED BAND OF DEFORMATION RAIN OVER FAR SOUTH CENTRAL NORTH DAKOTA THROUGH THE JAMES RIVER VALLEY AND INTO EASTERN NORTH DAKOTA. THE RAIN WILL EXIT THE JAMES RIVER VALLEY SATURDAY MORNING WITH CLEARING SKIES OVER WESTERN NORTH DAKOTA. WE WILL NEED TO MONITOR FOR POSSIBLE FROST HIGHLIGHTS ACROSS THE WEST ON SATURDAY MORNING WITH LOWS POSSIBLY FALLING INTO THE MID TO UPPER 30S IF SKIES CLEAR AND WINDS SUBSIDE. UPPER LEVEL RIDGING BUILDS OVER THE AREA THROUGH THE REMAINDER OF THE WEEKEND WITH TEMPERATURES WARMING INTO THE 70S BY SUNDAY AND MONDAY. A QUASI-ZONAL FLOW THEN TAKES SHAPE THROUGH MID WEEK WITH THE STORM TRACK SITUATED NORTH OF THE BORDER. THUS MAINLY DRY CONDITIONS ARE EXPECTED EARLY NEXT WEEK. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 651 AM CDT THU SEP 26 2013 SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS REMAIN IN THE FORECAST FOR KMOT WITH A VCSH AT KISN/KDIK/KBIS. KJMS WILL HAVE A VCTS THROUGH 16Z TODAY. EXPECT IFR TO MVFR CIGS THROUGH 18Z WITH CIGS LIFTING TO LOW VFR. GUSTY WESTERLY TO SOUTHWESTERLY WINDS WILL DEVELOP BY LATE MORNING AT KDIK AND EARLY AFTERNOON AT KMOT. CIGS WILL AGAIN DETERIORATE THURSDAY NIGHT AS SHOWERS DEVELOP IN THE SOUTHWEST AND SPREAD NORTHEAST THROUGH 12Z FRIDAY. && .BIS WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY UNTIL 7 PM CDT /6 PM MDT/ THIS EVENING FOR NDZ018- 019-021-031>033-040-041-043-044. WIND ADVISORY FROM 2 PM THIS AFTERNOON TO 9 PM CDT THIS EVENING FOR NDZ002>004-010>012. && $$ UPDATE...TM SHORT TERM...KS LONG TERM...TWH AVIATION...KS
AREA FORECAST DISCUSSION
NWS BISMARCK ND
651 AM CDT THU SEP 26 2013 .UPDATE... ISSUED AT 651 AM CDT THU SEP 26 2013 LOW PRESSURE SITUATED OVER CENTRAL NORTH DAKOTA WITH SCATTERED SHOWERS AND THUNDERSTORMS LIFTING FROM EAST CENTRAL INTO NORTHEAST NORTH DAKOTA...AND SHOWERS EXTENDING BACK INTO CENTRAL NORTH DAKOTA JUST AHEAD OF THE LOW. COLD NORTHERLY FLOW HAS MOVED INTO WESTERN NORTH DAKOTA WITH IFR CLOUDINESS SPREADING EAST ACROSS WESTERN NORTH DAKOTA. UPDATED WEATHER POPS TO MATCH WITH LATEST RADAR IMAGERY...AND EXTRAPOLATING NORTHEAST THROUGH THE MORNING. LIMITED MENTION OF THUNDER TO THE EAST CENTRAL AND FAR NORTH CENTRAL. INCREASED SKY COVER OVER THE WEST THROUGH THE MORNING TO ACCOUNT FOR THE LOW STRATUS. EXPECT THIS TO DISSIPATE BY LATE MORNING AND AFTERNOON WITH STRONG SUBSIDENCE MOVING INTO WESTERN NORTH DAKOTA. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 249 AM CDT THU SEP 26 2013 MAIN CONCERN TODAY WILL BE THUNDERSTORMS EARLY THIS MORNING FOLLOWED BY A WIND ADVISORY SOUTHWEST THROUGH NORTH CENTRAL. HAVE UTILIZED A BLEND OF ALL MODELS...BUT SPECIFICALLY THE HRRR FOR AREAL COVERAGE OF PRECIPITATION THIS MORNING AND NAM/GFS FOR THE WIND ADVISORY. THE LATEST WATER VAPOR IMAGERY ALONG WITH SPC MESOSCALE ANALYSIS CONTINUES TO SHOW THE H3 JET STREAK WORKING ITS WAY THROUGH WYOMING AND INTO SOUTH DAKOTA. UPPER DIVERGENCE FIELD ASSOCIATED WITH THE LEFT EXIT REGION CENTERED OVER CENTRAL/NORTHERN NORTH DAKOTA AS ISOLATED THUNDERSTORMS CONTINUE TO ESCALATE UPWARDS. SURFACE LOW PRESSURE IN SOUTHERN SOUTH DAKOTA WILL BEGIN TO MOVE NORTH ALONG A COLD FRONT WHICH IS NOW LOCATED FROM NEAR OXBOW SASKATCHEWAN...SOUTH TO MINOT AND INTO LEMMON SOUTH DAKOTA. AS THE JET STREAK AND UPPER DIVERGENCE FIELD SHIFT FURTHER NORTH THROUGH THE MORNING...THE SURFACE LOW WILL DEEPEN AS IT ENTERS SOUTHERN SASKATCHEWAN THIS AFTERNOON. A TIGHT PRESSURE GRADIENT WILL ENSUE...RESULTING IN A MARGINAL WIND ADVISORY EVENT. WITH SUSTAINED WINDS VERY NEAR 30 MPH AND GUSTS TO 40 MPH OVER A FAIRLY LARGE AREA...DECIDED TO ISSUE A WIND ADVISORY FOR THE SOUTHWEST AND NORTH CENTRAL ZONES. WINDS WILL INCREASE FIRST ACROSS THE SOUTHWEST LATE THURSDAY MORNING...THEN TRANSLATE INTO NORTH CENTRAL BEGINNING IN THE EARLY AFTERNOON. WINDS WILL THEN DIMINISH FROM SOUTH TO NORTH THURSDAY EVENING. AS FAR AS SHOWERS AND THUNDERSTORMS...THERE WILL BE A DIMINISHING EFFECT AS THE SURFACE LOW MOVES FROM SOUTH TO NORTH TODAY. MAIN INSTABILITY WASHES OUT BY 18Z IN THE NORTH AND HAVE ENDED THE THUNDERSTORM THREAT IN THE GRIDDED FORECAST AT THAT TIME. DRY WEATHER COMMENCES CENTRAL AND SOUTH TODAY INTO EARLY TONIGHT. THE NEXT ROUND OF SHOWERS BEGINS IN THE SOUTHWEST EARLY TONIGHT AND GRADUALLY EXPANDS NORTHEAST OVERNIGHT. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 249 AM CDT THU SEP 26 2013 THE MAIN FORECAST ISSUE IN THE LONG TERM PERIOD WILL BE PRECIPITATION CHANCES AND PLACEMENT FRIDAY THROUGH SATURDAY MORNING. THERE IS STILL SOME DISAGREEMENT AMONG THE DETERMINISTIC MODELS WITH PRECIPITATION ACROSS NORTH DAKOTA ON FRIDAY. HOWEVER...THERE IS MUCH BETTER AGREEMENT FRIDAY NIGHT INTO SATURDAY MORNING. WE BEGIN THE LONG TERM PERIOD ON FRIDAY WITH AN UPPER LEVEL TROUGH OVER THE NORTHERN AND CENTRAL ROCKIES. SHEARED VORTICITY ALONG THE LEADING EDGE OF THE TROUGH EXTENDS ACROSS EASTERN MONTANA AND WESTERN NORTH DAKOTA. THE ECMWF IS SHOWING A BROAD AREA OF LIGHT TO MODERATE RAIN LIFTING SOUTHWEST TO NORTHEAST ACROSS THE FORECAST AREA...WHILE THE GFS/GEM CONTINUE TO INDICATE TWO SEPARATE AREAS OF PRECIPITATION...ONE OVER THE WESTERN DAKOTAS ASSOCIATED WITH THE UPPER LEVEL TROUGH...AND ANOTHER OVER EASTERN NORTH DAKOTA ASSOCIATED WITH THE SURFACE SYSTEM...AND A DRY SLOT OVER CENTRAL NORTH DAKOTA. DUE TO CONTINUED DIFFERENCES...WILL SETTLE ON A BROAD BRUSH OF CHANCE TO HIGH CHANCE POPS UNTIL THERE IS BETTER MODEL AGREEMENT. EITHER WAY IT WILL BE QUITE COOL AND CLOUDY WITH SCATTERED LIGHT RAIN AND HIGHS MAINLY IN THE 50S. THERE IS BETTER MODEL AGREEMENT AS THE KICKER SHORTWAVE ROUNDS THE BASE OF THE UPPER TROUGH AND LIFTS INTO THE CENTRAL PLAINS FRIDAY NIGHT. STRONG 2D FRONTOGENESIS SETS UP OVER THE EASTERN DAKOTAS FRIDAY NIGHT AS THE SURFACE LOW TRACKS FROM THE CENTRAL PLAINS INTO NORTHERN MINNESOTA BY SATURDAY MORNING. THIS RESULTS IN AN ENHANCED BAND OF DEFORMATION RAIN OVER FAR SOUTH CENTRAL NORTH DAKOTA THROUGH THE JAMES RIVER VALLEY AND INTO EASTERN NORTH DAKOTA. THE RAIN WILL EXIT THE JAMES RIVER VALLEY SATURDAY MORNING WITH CLEARING SKIES OVER WESTERN NORTH DAKOTA. WE WILL NEED TO MONITOR FOR POSSIBLE FROST HIGHLIGHTS ACROSS THE WEST ON SATURDAY MORNING WITH LOWS POSSIBLY FALLING INTO THE MID TO UPPER 30S IF SKIES CLEAR AND WINDS SUBSIDE. UPPER LEVEL RIDGING BUILDS OVER THE AREA THROUGH THE REMAINDER OF THE WEEKEND WITH TEMPERATURES WARMING INTO THE 70S BY SUNDAY AND MONDAY. A QUASI-ZONAL FLOW THEN TAKES SHAPE THROUGH MID WEEK WITH THE STORM TRACK SITUATED NORTH OF THE BORDER. THUS MAINLY DRY CONDITIONS ARE EXPECTED EARLY NEXT WEEK. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 651 AM CDT THU SEP 26 2013 SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS REMAIN IN THE FORECAST FOR KMOT WITH A VCSH AT KISN/KDIK/KBIS. KJMS WILL HAVE A VCTS THROUGH 16Z TODAY. EXPECT IFR TO MVFR CIGS THROUGH 18Z WITH CIGS LIFTING TO LOW VFR. GUSTY WESTERLY TO SOUTHWESTERLY WINDS WILL DEVELOP BY LATE MORNING AT KDIK AND EARLY AFTERNOON AT KMOT. CIGS WILL AGAIN DETERIORATE THURSDAY NIGHT AS SHOWERS DEVELOP IN THE SOUTHWEST AND SPREAD NORTHEAST THROUGH 12Z FRIDAY. && .BIS WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY FROM NOON CDT /11 AM MDT/ TODAY TO 7 PM CDT /6 PM MDT/ THIS EVENING FOR NDZ018-019-021-031>033-040-041-043-044. WIND ADVISORY FROM 2 PM THIS AFTERNOON TO 9 PM CDT THIS EVENING FOR NDZ002>004-010>012. && $$ UPDATE...TWH SHORT TERM...KS LONG TERM...TWH AVIATION...KS
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
ISSUED BY NATIONAL WEATHER SERVICE PITTSBURGH PA 942 AM EDT THU SEP 26 2013 .SYNOPSIS... HIGH PRESSURE BUILDS IN TODAY...REMAINING THROUGH MUCH OF THE WEEKEND. A WEAK COLD FRONT CROSSES EARLY NEXT WEEK THEN A RETURN TO DRY WEATHER. && .NEAR TERM /THROUGH TONIGHT/... H5 CYCLONE BECOMES AN OPEN WAVE TODAY AND MOVES EAST OF THE BLUE RIDGE. MORNING FOG E OF THE OHIO RIVER ACROSS THE MTN STATE OF WV INTO THE SWRN VA COAL FIELDS WILL DISSIPATE BY 15Z. THIS COINCIDES WIT THE LATEST HRRR TOTAL CLOUD COVER OUTPUT. WILL BE WATCHING POSSIBLE ADVECTION OF STRATUS ACROSS EASTERN POCAHONTAS COUNTY DURING THE PREDAWN HOURS BASED ON LATEST H9-H8 RH TRENDS WITH ERLY FLOW. OTHERWISE BUILDING MID LVL HEIGHTS OWE TO A WARMER AFTN. && .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/... MODELS IN GENERAL AGREEMENT WITH UPPER RIDGE SLOWLY MOVING EASTWARD THROUGH THE PERIOD. AS IT DOES A WEAK COOL FRONT WILL APPROACH THE CWA FROM THE WEST AND ARRIVE LATE SUNDAY. WE WILL HAVE MOSTLY SUNNY WARM DAYS AND RELATIVELY COOL EVENINGS WITH FOG DEVELOPING AT LEAST FRIDAY MORNING AND TO A LESSER EXTENT AGAIN ON SATURDAY MORNING. THE MAIN EFFECT FROM THE FRONT WILL BE AN INCREASE IN CLOUDS SATURDAY NIGHT AS MOISTURE INCREASES FROM THE SOUTH. ON SUNDAY LOOK FOR CLOUDS TO CONTINUE TO INCREASE AND THE CHANCE OF SHOWERS TO INCREASE AS WELL FROM THE WEST. TEMPERATURES ARE A BLEND OF CONSENSUS GUIDANCE AND CURRENT GRID TEMPS. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... THIS PERIOD WILL BE DOMINATED BY A WEAKENING COOL FRONT THAT WILL MOVE EASTWARD ACROSS THE AREA SUNDAY NIGHT AND MONDAY MORNING. SUPPORTING UPPER TROUGH FLATTENS OUT AS IT APPROACHES...WITH MUCH OF THE ENERGY GOING INTO FLATTENING THE UPPER RIDGE. STILL...ENOUGH MOISTURE RETURN AND UPPER SUPPORT TO SUPPORT SCATTERED SHOWERS WITH THE FRONT. OTHERWISE...WITH A PROGRESSIVE WEST TO NORTHWEST UPPER FLOW...FRONT MOVES OUT BY MONDAY EVENING WITH HIGH PRESSURE TAKING CHARGE INTO THE MIDDLE OF NEXT WEEK. ONLY SLIGHT COOLING BEHIND THE FRONT WITH LOTS OF SUNSHINE TUESDAY AND WEDNESDAY HELPING TO BOOST TEMPERATURES BACK INTO THE 70S. HOWEVER...MONDAY NIGHT THROUGH WEDNESDAY NIGHT WILL COOL BE DUE TO CLEAR SKIES AND DRY AIR. && .AVIATION /14Z THURSDAY THROUGH MONDAY/... UPPER LEVEL SYSTEM WILL MOVE EASTWARD EARLY THIS MORNING. DENSE FOG WILL BE SLOW TO LIFT. A CUMULUS DECK WILL THEN FORM OVER SOUTHERN AND EASTERN PORTIONS OF THE AREA TODAY...POSSIBLY BEGINNING AS MVFR. DENSE RIVER VALLEY FOG CAN BE EXPECTED TONIGHT. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z FRIDAY... FORECAST CONFIDENCE: MEDIUM THIS MORNING...HIGH THIS AFTERNOON AND TONIGHT. ALTERNATE SCENARIOS: TIMING OF FOG LIFTING THIS MORNING AND FORMING TONIGHT COULD VARY. 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. AFTER 12Z FRIDAY... DENSE RIVER VALLEY FOG FRIDAY MORNING. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...29 NEAR TERM...29
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
623 AM CDT THU SEP 26 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 321 AM CDT THU SEP 26 2013 AT 3 AM...A 1020 MB HIGH WAS CENTERED NORTH OF LAKE HURON. EASTERLY WINDS ON THE SOUTHERN PERIPHERY OF THIS HIGH CONTINUES TO BRING LOWER AND MID 40 DEW POINTS INTO CENTRAL AND NORTH-CENTRAL WISCONSIN. THE COMBINATION OF THESE DEW POINTS ALONG WITH CLEAR SKIES AND LIGHT WINDS HAS ALLOWED TEMPERATURES THESE AREAS TO COOL INTO THE LOWER AND MID 40S. WITH THESE TEMPERATURES COOLER THAN THE WATER TEMPERATURES...STEAM FOG HAS DEVELOPED IN THIS AREA. THERE ARE EVEN A FEW REPORTS OF DENSE FOG AT VOLK FIELD AND WAUTOMA. WITH BUFKIT RAP SOUNDINGS CONTINUING TO SHOW THAT THE WINDS BELOW 900 MB WILL BE INCREASING TO AROUND 10 KNOTS BY SUNRISE...NOT EXPECTING THIS FOG TO BECOME AS WIDESPREAD AS WEDNESDAY MORNING. HOWEVER WITH THIS SAID...WE ARE STILL CONSIDERING A DENSE FOG ADVISORY IN ADAMS AND JUNEAU COUNTIES IN CENTRAL WISCONSIN. SHERIFF DEPARTMENTS IN BOTH OF THESE COUNTIES ARE REPORTING PATCHY DENSE FOG. THE RAP WOULD SUGGEST THAT THE LOW LEVEL MOISTURE WILL INCREASE THROUGH THE REMAINDER OF THIS MORNING. MEANWHILE NAM/WRF SHOWS THAT THIS LOW LEVEL MOISTURE MIXES OUT BY 26.14Z. FOR TODAY...HIGH PRESSURE WILL PROVIDE ANOTHER SUNNY DAY ACROSS THE UPPER MISSISSIPPI RIVER VALLEY. AS DIURNAL HEATING MIXES OUT THE NOCTURNAL INVERSION THIS MORNING...EXPECT WIND GUSTS TO CLIMB INTO THE 15 TO 30 MPH BETWEEN 10 AM AND NOON...AND THEN CONTINUE THROUGH THE AFTERNOON. LIKE YESTERDAY...IT LOOKS LIKE THE AREA WILL MIX TO AROUND 875 MB. THIS WILL YIELD TEMPERATURES IN THE LOWER TO MID 70S NORTH OF INTERSTATE 94...AND FROM THE MID 70S TO AROUND 80 ACROSS THE REMAINDER OF THE AREA. FOR TONIGHT...THE CENTER OF SURFACE HIGH WILL DRIFT EAST INTO QUEBEC. THIS WILL ALLOW THE COLD FRONT...CURRENTLY LOCATED OVER THE CENTRAL DAKOTAS...TO MOVE EAST INTO WESTERN AND NORTHERN MINNESOTA. AS THIS OCCURS...SOME MOISTURE BETWEEN 600 AND 700 MB WILL MOVE EAST INTO THE FORECAST AFTER AFTER 27.08Z. THE NOCTURNAL INVERSION WILL QUICKLY THIS EVENING WITH THE LOSS OF DIURNAL HEATING. AS THIS OCCURS...THE WIND GUSTS WILL DIMINISH. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 321 AM CDT THU SEP 26 2013 FROM FRIDAY AFTERNOON INTO FRIDAY NIGHT...THE 26.00Z MODELS ARE IN VERY GOOD AGREEMENT THAT THE COLD FRONT WILL MOVE EAST INTO WESTERN MINNESOTA DURING THE AFTERNOON AND EVENING...AND THEN IT STALLS ITS EASTWARD PROGRESS ON FRIDAY NIGHT AS A SURFACE LOW MOVES NORTH ALONG IT. WITH SOUNDINGS CONTINUING TO SHOW CAPPING BETWEEN 800 AND 650 MBS AND DRY AIR AHEAD OF THIS FRONT...NOT EXPECTING ANY PRECIPITATION TO OCCUR AHEAD OF IT....THUS KEPT THE FORECAST DRY. FROM SATURDAY INTO SATURDAY EVENING...THE MODELS CONTINUE TO SHOW THAT THE SURFACE COLD FRONT AND SHORT WAVE TROUGH WILL MOVE QUICKLY EAST ACROSS THE AREA. LIKE THE PAST DAYS...THE 0-6 KM SHEAR REMAINS ABOVE 40 KNOTS ALONG AND IN THE WAKE OF THE FRONT. HOWEVER THE ML CAPES REMAIN GENERALLY LESS THAN 100 J/KG...SO STILL NOT CONCERNED THAT THE AREA WILL EXPERIENCE ANY SEVERE WEATHER. JUST TOO LITTLE INSTABILITY FOR THE AMOUNT SHEAR. OVERALL...ACTUALLY THINK THAT OUR BEST CHANCE OF THUNDER WILL ACTUALLY COME FROM MORE SLANTWISE THAN UPRIGHT CONVECTION. DUE TO THE CONSISTENCY OF THE TIMING WITH THE FRONTOGENESIS...RAISED THE PRECIPITATION CHANCES INTO THE 75 TO 84 PERCENT RANGE. THINKING WITH THE SPEED OF THE SHORT WAVE TROUGH AND FRONT THAT THE PRECIPITATION WILL LIKELY ONLY LAST 2 TO 4 HOURS IN ANY LOCATION. FROM TUESDAY INTO WEDNESDAY...THE MODELS ARE NOW SHOWING THAT THE SHORT WAVE WILL PASS WELL NORTH OF THE AREA. DUE TO THIS...THE PRECIPITATION CHANCES WERE REMOVED FROM THE FORECAST. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 623 AM CDT THU SEP 26 2013 THE MAIN FOCUS IS ON THE POTENTIAL FOR FOG THIS MORNING FOLLOWED BY HOW WINDY IT WILL BE THIS AFTERNOON. DENSE FOG HAS FORMED ACROSS THE EASTERN HALF OF WISCONSIN AND IS TRYING TO SPREAD WEST WARD TOWARD LSE. LOW LEVEL WINDS APPEAR TO BE STRONGEST THERE AND SHOULD KEEP CONDITIONS VFR OR MVFR AT THE WORST. WITH THIS TIGHTENING PRESSURE GRADIENT EXPECTED TODAY ACROSS THE REGION...WINDS WILL QUICKLY INCREASE LATER THIS MORNING ON INTO THE AFTERNOON. SUSTAINED SOUTHEAST WINDS OF 12-18KTS WITH GUSTS UP TO 26KTS ARE FORECAST THROUGH THE AFTERNOON BEFORE DIMINISHING THIS EVENING. SKIES WILL MAINLY BE CLEAR THOUGH SOME SCT-BKN 4KFT STRATOCUMULUS COMING OUT OF IOWA MAY LINGER FOR MUCH OF THE DAY. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR WIZ034- 042>044. MN...NONE. IA...NONE. && $$ SHORT TERM...BOYNE LONG TERM...BOYNE AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1153 AM MDT THU SEP 26 2013 .UPDATE... ISSUED AT 1002 AM MDT THU SEP 26 2013 THE 12Z NAM12 CONTINUES TO SHOW SIGNIFICANT SNOWFALL OVER THE HIGHER TERRAIN OF THE EASTERN UINTA MOUNTAINS IN NORTHEAST UT. CURRENT FORECAST OF 4-8 INCHES ABOVE 9000 FT REMAINS REASONABLE WITH SOME LOCALLY HIGHER AMTS POSSIBLE. SINCE THIS LOOKS LIKE THE FIRST GOOD EARLY-SEASON SNOW EVENT FOR THIS AREA...DECIDED TO HEIGHTEN AWARENESS EVEN MORE BY UPGRADING THE CURRENT WINTER WEATHER ADVISORY FOR THE EASTERN UINTA MTNS (UT ZONE 23) TO A WINTER STORM WARNING. ANTICIPATE THE BEST SNOW ACCUMULATIONS TO OCCUR BETWEEN MIDNIGHT AND NOON FRI. FOR WESTERN COLORADO...EARLY LOOK AT THE MODELS INDICATE THAT SNOW LEVELS REMAIN HIGH UNTIL LATE TONIGHT AND FRIDAY MORNING. USING WET-BULB ZERO AS AN INDICATOR...SNOW LEVELS STAY ABOVE 10K ALONG THE DIVIDE DOWN ACROSS THE SAN JUANS UNTIL AFTER 12Z FRI...WHILE DROPPING TO AROUND 9K OVER GRAND MESA BY 12Z FRI. ONCE THE FRONT PASSES...SNOW LEVELS SHOULD DROP QUICKLY. IN OTHER NEWS...WILL CONTINUE WITH THE CURRENT WIND ADVISORY FOR THE VALLEYS OF SE UT AND PORTIONS OF SW CO TODAY. LATEST HIGH- RESOLUTION HRRR MODEL INDICATES STRONG WIND GUSTS EXPANDING INTO NW CO (CO ZONES 1 AND 2) THIS AFTERNOON AS THE COLD FRONT TEMPORARILY RETREATS. WILL CONTINUE TO EVALUATE AND WATCH IN CASE THE WIND ADVISORY NEEDS EXPANSION INTO THIS AREA. UPDATE ISSUED AT 813 AM MDT THU SEP 26 2013 UDOT WEBCAMS REVEALED SOME LIGHT SNOW AT 8000 FT HAD OCCURRED ACROSS THE ERN UINTA MTNS LAST NIGHT AND THIS MORNING BEHIND THE COLD FRONT. DID A QUICK UPDATE TO THE GRIDDED AND WORDED FORECASTS FOR UT ZONE 23 TO TAKE THIS INTO ACCOUNT. EXPECT MUCH OF THIS SNOW WILL MELT TODAY AS THE FRONT WAVERS BACK NORTHWEST AND TEMPS RISE INTO THE 40S. && .SHORT TERM...(TODAY THROUGH FRIDAY) ISSUED AT 338 AM MDT THU SEP 26 2013 THE COLD FRONT ASSOCIATED WITH THE BROAD UPPER-LEVEL TROUGH ENCOMPASSING MUCH OF THE NORTHERN INTERMOUNTAIN WEST LAY ALONG A KBCE-35N KGJT-KEEO-K3MW LINE EARLY THIS MORNING. SOME VIRGA WAS EVIDENT IN KGJX RADAR IMAGERY RESULTING FROM OVERRUNNING OF THE FRONT. LITTLE MOISTURE ENTRAINED IN THE SOUTHWEST FLOW WHICH EXPLAINS WHY MOISTURE WASN/T REACHING THE GROUND. THE TROUGH IS EXPECTED TO DIG SOUTHWARD IN RESPONSE TO A 125KT JET PLUNGING SOUTHWARD ON ITS BACK SIDE. THIS WILL CAUSE THE AXIS OF THE TROUGH TO LOSE SOME OF ITS POSITIVE TILT WHICH...IN TURN...WILL RESULT IN THE FRONT LIFTING BACK TO THE NORTHWEST AS A WARM FRONT. BECAUSE SYSTEM DRAWING FROM DRYER AIRMASS TO THE SOUTH CUT POPS ACROSS ALL BUT THE EASTERN UINTA MOUNTAINS TODAY. IN THIS REGION INSTABILITY SUPPORTS THE FORMATION OF A FEW EMBEDDED THUNDERSTORMS. PRE-FRONTAL SOUTHWEST WINDS WILL CONTINUE TO BE RATHER STRONG ACROSS THE AREA AGAIN THIS AFTERNOON. A CORE OF 45 KNOT WINDS AT THE 7H LEVEL OVER SOUTHEAST UTAH AND SOUTHWEST COLORADO APPEARS DURING THE AFTERNOON AS THE MID-LEVEL AND SURFACE GRADIENTS TIGHTEN WITH THE APPROACH OF THE TROUGH. GIVEN YESTERDAY/S WINDS...NO REASON TO BELIEVE WIND ADVISORY FOR LOWER ELEVATIONS OF SOUTHEAST UTAH AND SOUTHWEST COLORADO WON/T VERIFY. THEREFORE...WILL CONTINUE THE WIND ADVISORY FROM NOON TO 7 PM. SINCE MODELS WERE IN GOOD AGREEMENT WITH PLACEMENT OF THE 7H WIND MAX OVER THE ADVISED AREA AND WERE CONSISTENT WITH PREVIOUS RUNS HAVE NO PLANS TO EXPAND WIND HILITES. THOUGH MUCH OF THE FORECAST AREA WILL BE IN THE WARM SECTOR AGAIN TODAY...COOLING AT 7H LEVELS WILL RESULT IN A FEW DEGREES OF COOLING THIS AFTERNOON. MET GUIDANCE SEEMED TO BE PICKING UP ON THIS TREND BETTER THAN THE MAV GUIDANCE DESPITE THE FACT THAT THE GFS SHOWED SIMILAR 7H COOLING. TONIGHT AND FRIDAY...120+KT JET IS DROPPING DOWN THE CALIFORNIA COAST THIS MORNING AND WILL HELP CARVE OUT THE WESTERN TROF TODAY AS IT REFORMS ON THE DOWNSTREAM SIDE OVER THE ROCKIES THIS EVENING. THIS WILL BEGIN TO PUSH THE TROF EASTWARD SUPPLYING A STRONG AREA OF ASCENT AND INSTABILITY TO NORTHERN UTAH...WITH THE TROP FOLD LOWERING TO NEAR 450MB. MODELS STILL WANT TO PUSH MOISTURE UP THE 315K SURFACE THROUGH TODAY...BRINGING PWATS UP TO NEAR NORMAL FOR LATE SEPTEMBER. THIS IS LESS THAN WHAT HAS BEEN IN PLACE LATELY BUT THE DYNAMICS WITH THIS STORM LOOK SUFFICIENT TO BRING A PERIOD OF MODERATE SNOWFALL TO THE NORTHWEST CWA OVERNIGHT. A COLD FRONT MOVING THROUGH NORTHEAST UTAH THIS EVENING APPEARED TO LINK UP WITH THE UPPER ASCENT BY MID LEVEL FRONTOGENESIS...WITH THE NAM EVEN HINTING AT A COUPLED JET OVER THIS REGION. MODELS ALSO HINT AT THE DRY CONVEYOR BELT LIFTING ACROSS THIS REGION WITH PV LOBE PROVIDING INSTABILITY AND HAVE PUT ISOLATED THUNDERSTORMS IN THE FORECAST. THE INSTABILITY...MOISTURE AND LIFT ALL POINT TO A FEW HOURS OF MODERATE TO HEAVY SNOWFALL. IT SHOULD BE NOTED THAT SNOW WAS SEEN TODAY AT 8000 FEET IN THE EASTERN UINTAS THOUGH DYNAMICS WHERE WEAKER. GIVEN THE ABOVE...FELT ADVZY LEVEL SNOWS MOST LIKELY TO IMPACT TRAVEL ROUTES WITH HIGHER AMOUNTS OVER 10000 FEET. MODELS KEEP THE DENDRITIC LAYER SATURATED UP NORTH SO POPS REMAIN THE HIGHEST HERE. A MOIST SOUTHWEST FLOW AND INSTABILITY WILL BRING SOME CHANCE OF SNOWFALL TO THE HIGHER MOUNTAINS IN THE CENTRAL AND SOUTH OVERNIGHT. THERMO PROFILES AND DRIER ICE LAYER INDICATES HOWEVER THIS WILL BE FAIRLY LIGHT AND MAINLY ABOVE THE 10000 FT LEVEL. THE FRONT WILL CONTINUE TO PROGRESS ACROSS THE CWA ON FRIDAY...DRIVEN BY THE PROGRESSIVE TROF ALOFT. MOISTURE LOOKS TO BE ON THE WAY OUT BUT INSTABILITY RE- ENFORCED BY COLD AIR ALOFT. THE NORTHERLY FLOW WILL CONTINUE TO FAVOR THE EASTERN UINTAS THROUGH THE DAY AS COLD AIR FILTERS IN. SCATTERED SHOWERS ALSO CONTINUE ALONG THE FRONT AND THE HIGHER TERRAIN OF WESTERN COLORADO. PROFILES OVER MANY VALLEY AREAS WERE QUITE DRY IN THE LOWER LEVELS SO BACKED OFF ON POPS IN SEVERAL PLACES. FRIDAY HIGHS WILL FALL BY SOME 10 TO 15 DEGREES BEHIND THE FRONT. .LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 338 AM MDT THU SEP 26 2013 FRIDAY NIGHT INTO SATURDAY...CLEARING SKIES IN THE DRIER AIRMASS WILL SPELL A COLD NIGHT ACROSS MUCH OF THE REGION AND FREEZING TEMPERATURES WILL BE MORE COMMON ACROSS SOME OF THE LOWER ELEVATIONS. LOOKS LIKE SOUTHERN FOOTHILLS OF THE SAN JUANS... NORTHERN PLATEAUS...UINTA BASIN AND UPPER COLORADO MAY ALL BE IN THREAT OF A SEASON ENDING FREEZE. RIDGING BUILDS IN FOR SATURDAY AND TEMPERATURES WILL BEGIN A TREND BACK UPWARDS. THE COLD START AND STRONGER INVERSION WILL KEEP TEMPERATURES ON THE COOL SIDE OF NORMAL...BUT A DECENT START TO THE WEEKEND SHOULD COMMENCE. SATURDAY NIGHT TO WEDNESDAY...FLAT ZONAL FLOW PREDOMINATES THROUGH THE REMAINDER OF THE WEEK AND INTO THE MIDDLE OF THE COMING WEEK. AS A RESULT...EXPECT DRY AND MILD CONDITIONS THROUGH WEDNESDAY. TEMPERATURES WILL WARM A BIT RISING TO NEAR NORMAL BY MONDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1152 AM MDT THU SEP 26 2013 A COLD FRONT FROM THE UTAH BOOK CLIFFS TO THE FLATTOPS WILL PUSH TO THE NORTHWEST THIS AFTERNOON. THE FRONT WILL EXTEND FROM NEAR KBCE TO KRWL LINE THIS AFTERNOON WHEN WINDS REACH THEIR PEAK. THE STRONGEST WINDS ARE EXPECTED OVER SOUTHEAST UTAH AND PORTIONS OF SOUTHWEST COLORADO WHERE SUSTAINED WINDS FROM 20 TO 30 MPH WITH GUSTS TO NEAR 50 MPH ARE ANTICIPATED. EXPECT ANOTHER DAY OF INCREASED MECHANICAL TURBULENCE OVER RIDGETOPS. ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS ARE POSSIBLE OVER NORTHEAST UT AND EXTREME NORTHWEST CO THIS AFTERNOON INTO EARLY EVENING. CIGS LOWER TO MOUNTAIN TOP LEVEL TONIGHT WITH THE COLD FRONT RETURNING THROUGH NORTHEAST UT BY 06Z...AND ACROSS WESTERN COLORADO BY 18Z FRI. VALLEY RAIN AND MOUNTAIN RAIN/SNOW WILL INCREASE IN COVERAGE AFTER 06Z MAINLY NORTH OF INTERSTATE 70. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...WIND ADVISORY UNTIL 7 PM MDT THIS EVENING FOR COZ020-021. FREEZE WATCH FROM LATE FRIDAY NIGHT THROUGH SATURDAY MORNING FOR COZ002-008-021>023. UT...WIND ADVISORY UNTIL 7 PM MDT THIS EVENING FOR UTZ022-027-029. WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 PM MDT FRIDAY FOR UTZ023. && $$ UPDATE...JAD SHORT TERM...NL/15 LONG TERM...15/NL AVIATION...JAD
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1002 AM MDT THU SEP 26 2013 .UPDATE... ISSUED AT 1002 AM MDT THU SEP 26 2013 THE 12Z NAM12 CONTINUES TO SHOW SIGNIFICANT SNOWFALL OVER THE HIGHER TERRAIN OF THE EASTERN UINTA MOUNTAINS IN NORTHEAST UT. CURRENT FORECAST OF 4-8 INCHES ABOVE 9000 FT REMAINS REASONABLE WITH SOME LOCALLY HIGHER AMTS POSSIBLE. SINCE THIS LOOKS LIKE THE FIRST GOOD EARLY-SEASON SNOW EVENT FOR THIS AREA...DECIDED TO HEIGHTEN AWARENESS EVEN MORE BY UPGRADING THE CURRENT WINTER WEATHER ADVISORY FOR THE EASTERN UINTA MTNS (UT ZONE 23) TO A WINTER STORM WARNING. ANTICIPATE THE BEST SNOW ACCUMULATIONS TO OCCUR BETWEEN MIDNIGHT AND NOON FRI. FOR WESTERN COLORADO...EARLY LOOK AT THE MODELS INDICATE THAT SNOW LEVELS REMAIN HIGH UNTIL LATE TONIGHT AND FRIDAY MORNING. USING WET-BULB ZERO AS AN INDICATOR...SNOW LEVELS STAY ABOVE 10K ALONG THE DIVIDE DOWN ACROSS THE SAN JUANS UNTIL AFTER 12Z FRI...WHILE DROPPING TO AROUND 9K OVER GRAND MESA BY 12Z FRI. ONCE THE FRONT PASSES...SNOW LEVELS SHOULD DROP QUICKLY. IN OTHER NEWS...WILL CONTINUE WITH THE CURRENT WIND ADVISORY FOR THE VALLEYS OF SE UT AND PORTIONS OF SW CO TODAY. LATEST HIGH- RESOLUTION HRRR MODEL INDICATES STRONG WIND GUSTS EXPANDING INTO NW CO (CO ZONES 1 AND 2) THIS AFTERNOON AS THE COLD FRONT TEMPORARILY RETREATS. WILL CONTINUE TO EVALUATE AND WATCH IN CASE THE WIND ADVISORY NEEDS EXPANSION INTO THIS AREA. UPDATE ISSUED AT 813 AM MDT THU SEP 26 2013 UDOT WEBCAMS REVEALED SOME LIGHT SNOW AT 8000 FT HAD OCCURRED ACROSS THE ERN UINTA MTNS LAST NIGHT AND THIS MORNING BEHIND THE COLD FRONT. DID A QUICK UPDATE TO THE GRIDDED AND WORDED FORECASTS FOR UT ZONE 23 TO TAKE THIS INTO ACCOUNT. EXPECT MUCH OF THIS SNOW WILL MELT TODAY AS THE FRONT WAVERS BACK NORTHWEST AND TEMPS RISE INTO THE 40S. && .SHORT TERM...(TODAY THROUGH FRIDAY) ISSUED AT 338 AM MDT THU SEP 26 2013 THE COLD FRONT ASSOCIATED WITH THE BROAD UPPER-LEVEL TROUGH ENCOMPASSING MUCH OF THE NORTHERN INTERMOUNTAIN WEST LAY ALONG A KBCE-35N KGJT-KEEO-K3MW LINE EARLY THIS MORNING. SOME VIRGA WAS EVIDENT IN KGJX RADAR IMAGERY RESULTING FROM OVERRUNNING OF THE FRONT. LITTLE MOISTURE ENTRAINED IN THE SOUTHWEST FLOW WHICH EXPLAINS WHY MOISTURE WASN/T REACHING THE GROUND. THE TROUGH IS EXPECTED TO DIG SOUTHWARD IN RESPONSE TO A 125KT JET PLUNGING SOUTHWARD ON ITS BACK SIDE. THIS WILL CAUSE THE AXIS OF THE TROUGH TO LOSE SOME OF ITS POSITIVE TILT WHICH...IN TURN...WILL RESULT IN THE FRONT LIFTING BACK TO THE NORTHWEST AS A WARM FRONT. BECAUSE SYSTEM DRAWING FROM DRYER AIRMASS TO THE SOUTH CUT POPS ACROSS ALL BUT THE EASTERN UINTA MOUNTAINS TODAY. IN THIS REGION INSTABILITY SUPPORTS THE FORMATION OF A FEW EMBEDDED THUNDERSTORMS. PRE-FRONTAL SOUTHWEST WINDS WILL CONTINUE TO BE RATHER STRONG ACROSS THE AREA AGAIN THIS AFTERNOON. A CORE OF 45 KNOT WINDS AT THE 7H LEVEL OVER SOUTHEAST UTAH AND SOUTHWEST COLORADO APPEARS DURING THE AFTERNOON AS THE MID-LEVEL AND SURFACE GRADIENTS TIGHTEN WITH THE APPROACH OF THE TROUGH. GIVEN YESTERDAY/S WINDS...NO REASON TO BELIEVE WIND ADVISORY FOR LOWER ELEVATIONS OF SOUTHEAST UTAH AND SOUTHWEST COLORADO WON/T VERIFY. THEREFORE...WILL CONTINUE THE WIND ADVISORY FROM NOON TO 7 PM. SINCE MODELS WERE IN GOOD AGREEMENT WITH PLACEMENT OF THE 7H WIND MAX OVER THE ADVISED AREA AND WERE CONSISTENT WITH PREVIOUS RUNS HAVE NO PLANS TO EXPAND WIND HILITES. THOUGH MUCH OF THE FORECAST AREA WILL BE IN THE WARM SECTOR AGAIN TODAY...COOLING AT 7H LEVELS WILL RESULT IN A FEW DEGREES OF COOLING THIS AFTERNOON. MET GUIDANCE SEEMED TO BE PICKING UP ON THIS TREND BETTER THAN THE MAV GUIDANCE DESPITE THE FACT THAT THE GFS SHOWED SIMILAR 7H COOLING. TONIGHT AND FRIDAY...120+KT JET IS DROPPING DOWN THE CALIFORNIA COAST THIS MORNING AND WILL HELP CARVE OUT THE WESTERN TROF TODAY AS IT REFORMS ON THE DOWNSTREAM SIDE OVER THE ROCKIES THIS EVENING. THIS WILL BEGIN TO PUSH THE TROF EASTWARD SUPPLYING A STRONG AREA OF ASCENT AND INSTABILITY TO NORTHERN UTAH...WITH THE TROP FOLD LOWERING TO NEAR 450MB. MODELS STILL WANT TO PUSH MOISTURE UP THE 315K SURFACE THROUGH TODAY...BRINGING PWATS UP TO NEAR NORMAL FOR LATE SEPTEMBER. THIS IS LESS THAN WHAT HAS BEEN IN PLACE LATELY BUT THE DYNAMICS WITH THIS STORM LOOK SUFFICIENT TO BRING A PERIOD OF MODERATE SNOWFALL TO THE NORTHWEST CWA OVERNIGHT. A COLD FRONT MOVING THROUGH NORTHEAST UTAH THIS EVENING APPEARED TO LINK UP WITH THE UPPER ASCENT BY MID LEVEL FRONTOGENESIS...WITH THE NAM EVEN HINTING AT A COUPLED JET OVER THIS REGION. MODELS ALSO HINT AT THE DRY CONVEYOR BELT LIFTING ACROSS THIS REGION WITH PV LOBE PROVIDING INSTABILITY AND HAVE PUT ISOLATED THUNDERSTORMS IN THE FORECAST. THE INSTABILITY...MOISTURE AND LIFT ALL POINT TO A FEW HOURS OF MODERATE TO HEAVY SNOWFALL. IT SHOULD BE NOTED THAT SNOW WAS SEEN TODAY AT 8000 FEET IN THE EASTERN UINTAS THOUGH DYNAMICS WHERE WEAKER. GIVEN THE ABOVE...FELT ADVZY LEVEL SNOWS MOST LIKELY TO IMPACT TRAVEL ROUTES WITH HIGHER AMOUNTS OVER 10000 FEET. MODELS KEEP THE DENDRITIC LAYER SATURATED UP NORTH SO POPS REMAIN THE HIGHEST HERE. A MOIST SOUTHWEST FLOW AND INSTABILITY WILL BRING SOME CHANCE OF SNOWFALL TO THE HIGHER MOUNTAINS IN THE CENTRAL AND SOUTH OVERNIGHT. THERMO PROFILES AND DRIER ICE LAYER INDICATES HOWEVER THIS WILL BE FAIRLY LIGHT AND MAINLY ABOVE THE 10000 FT LEVEL. THE FRONT WILL CONTINUE TO PROGRESS ACROSS THE CWA ON FRIDAY...DRIVEN BY THE PROGRESSIVE TROF ALOFT. MOISTURE LOOKS TO BE ON THE WAY OUT BUT INSTABILITY RE- ENFORCED BY COLD AIR ALOFT. THE NORTHERLY FLOW WILL CONTINUE TO FAVOR THE EASTERN UINTAS THROUGH THE DAY AS COLD AIR FILTERS IN. SCATTERED SHOWERS ALSO CONTINUE ALONG THE FRONT AND THE HIGHER TERRAIN OF WESTERN COLORADO. PROFILES OVER MANY VALLEY AREAS WERE QUITE DRY IN THE LOWER LEVELS SO BACKED OFF ON POPS IN SEVERAL PLACES. FRIDAY HIGHS WILL FALL BY SOME 10 TO 15 DEGREES BEHIND THE FRONT. .LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 338 AM MDT THU SEP 26 2013 FRIDAY NIGHT INTO SATURDAY...CLEARING SKIES IN THE DRIER AIRMASS WILL SPELL A COLD NIGHT ACROSS MUCH OF THE REGION AND FREEZING TEMPERATURES WILL BE MORE COMMON ACROSS SOME OF THE LOWER ELEVATIONS. LOOKS LIKE SOUTHERN FOOTHILLS OF THE SAN JUANS... NORTHERN PLATEAUS...UINTA BASIN AND UPPER COLORADO MAY ALL BE IN THREAT OF A SEASON ENDING FREEZE. RIDGING BUILDS IN FOR SATURDAY AND TEMPERATURES WILL BEGIN A TREND BACK UPWARDS. THE COLD START AND STRONGER INVERSION WILL KEEP TEMPERATURES ON THE COOL SIDE OF NORMAL...BUT A DECENT START TO THE WEEKEND SHOULD COMMENCE. SATURDAY NIGHT TO WEDNESDAY...FLAT ZONAL FLOW PREDOMINATES THROUGH THE REMAINDER OF THE WEEK AND INTO THE MIDDLE OF THE COMING WEEK. AS A RESULT...EXPECT DRY AND MILD CONDITIONS THROUGH WEDNESDAY. TEMPERATURES WILL WARM A BIT RISING TO NEAR NORMAL BY MONDAY. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 338 AM MDT THU SEP 26 2013 EXPECT STRONG SOUTHWEST WINDS TO GENERATE SIGNIFICANT MECHANICAL TURBULENCE AHEAD OF A COLD FRONT ASSOCIATED WITH AN EARLY FALL STORM CENTERED OVER SOUTH-CENTRAL IDAHO. THE FRONT WILL EXTEND FROM NEAR KBCE TO KRWL LINE THIS AFTERNOON WHEN WINDS REACH THEIR PEAK. THE STRONGEST WINDS ARE EXPECTED OVER SOUTHEAST UTAH AND PORTIONS OF SOUTHWEST COLORADO WHERE SUSTAINED WINDS FROM 20 TO 30 MPH WITH GUSTS TO NEAR 50 MPH ARE ANTICIPATED. IN ADDITION TO WINDS...SCATTERED LIGHT SHOWERS ARE EXPECTED TO CONTINUE OVER THE EASTERN UINTA MOUNTAINS THROUGH MUCH OF THE DAY RESULTING IN AREAS OF MOUNTAIN OBSCURATION. PRECIPITATION IS UNLIKELY TO AFFECT AIRPORTS WITHIN THE FORECAST AREA UNTIL AFTER 00Z/FRIDAY. AS THE SYSTEM FINALLY BEGINS TO PUSH ACROSS THE AREA TONIGHT SHOWERS WILL INCREASE IN COVERAGE WITH A FEW EMBEDDED THUNDERSTORMS ACROSS NORTHEAST UTAH AND NORTHWEST COLORADO THROUGH 06Z. AS A RESULT...THERE IS A GOOD CHANCE AIRPORTS NORTH OF THE I-70 CORRIDOR WILL EXPERIENCE MVFR CIGS AND/OR VSBY IN SHOWERS THROUGH 12Z. CHANCES DECREASE SOUTH OF I-70 WITH ONLY A SLIGHT CHANCE FOR THE SOUTHERNMOST AIRPORTS TONIGHT. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...WIND ADVISORY UNTIL 7 PM MDT THIS EVENING FOR COZ020-021. FREEZE WATCH FROM LATE FRIDAY NIGHT THROUGH SATURDAY MORNING FOR COZ002-008-021>023. UT...WIND ADVISORY UNTIL 7 PM MDT THIS EVENING FOR UTZ022-027-029. WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 PM MDT FRIDAY FOR UTZ023. && $$ UPDATE...JAD SHORT TERM...NL/15 LONG TERM...15/NL AVIATION...NL
AREA FORECAST DISCUSSION
NWS CARIBOU ME
631 PM EDT THU SEP 26 2013 .SYNOPSIS... LOW PRESSURE SOUTHEAST OF NOVA SCOTIA WILL SLOWLY MOVE EAST THIS EVENING AND ALLOW A LARGE RIDGE OF HIGH PRESSURE TO BUILD INTO OUR REGION THROUGH THE WEEKEND. && .NEAR TERM /THROUGH FRIDAY/... 631 PM UPDATE... THERE ARE A COUPLE OF BREAKS IN THE CLOUDS IN PARTS OF AROOSTOOK AND PISCATAQUIS COUNTIES. OTHERWISE...MOST AREAS ARE STILL OVC035. THE TIME HEIGHT FROM BOTH THE NAM AND GFS INDICATE A LOT OF MOISTURE BELOW 750 MILLIBARS TONIGHT...AND IT MAY BE VERY TOUGH TO GET RID OF THE CLOUDS UNTIL VERY LATE TONIGHT OR EARLY FRIDAY MORNING. THE HRRR APPEARS WAY TOO QUICK TO ERODE THE CLOUDS THIS EVENING. THE MAIN UPDATE WAS TO SLOW THE CLEARING BY A FEW HOURS THIS EVENING ACROSS THE NORTHERN HALF OF THE CWA. PREVIOUS DISCUSSION... HIGH PRESSURE BUILDS OVERNIGHT WITH CLEARING SKIES ADVECTING FROM THE CROWN OF MAINE SOUTHWARD TOWARDS BANGOR BY LATE NIGHT. LOWS WILL RANGE FROM NEAR 40F IN THE SJV TO THE UPPER 40S FOR DOWN EAST AND BANGOR WHERE CLOUDS WILL LINGER. THE LAST OF THE CLOUDS WILL MOVE SOUTHWARD OUT OF THE FORECAST AREA FRIDAY MORNING. THIS WILL PRODUCE A SUNNY DAY WITH SOME FAIR WEATHER CUMULUS AND HIGHS REACHING THE UPPER 60S TO LOW 70S. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/... DRY WEATHER PATTERN AND MILDER RIGHT THROUGH THIS TERM. A LARGE RIDGE OF HIGH PRES WILL MOVE INTO THE CWA OVER THE WEEKEND PROVIDING A WELL NEEDED STRETCH OF DRY WEATHER AND ABOVE NORMAL TEMPERATURES. DECIDED ON A BLEND OF THE EMCWFMOS/BCMOS FOR MIN TEMPERATURES FRIDAY NIGHT AND AGAIN SATURDAY NIGHT. FRIDAY NIGHT WILL BE THE COOLEST OF THE 2 W/OVERNIGHT LOWS EXPECTED IN THE UPPER 30S TO LOWER 40S. DAYTIME HIGHS WILL BE ABOVE NORMAL FOR LATE SEPTEMBER. DECIDED ON A BLEND OF THE BCMOS AND GMOS SHOWING READINGS EXPECTED TO HIT THE 70S FOR JUST ABOUT THE ENTIRE CWA. THE COAST COULD BE A FEW DEGREES COOLER GIVEN THE POTENTIAL FOR A SEA BREEZE AND WEAK ON SHORE WIND. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... THE FCST LOOKS TO CONTINUE ON THE DRY SIDE W/THE ONLY DISRUPTION BEING A SUB-TROPICAL LOW MOVING UP FROM THE BERMUDA AREA GIVING A GLANCING BLOW MAINLY TO THE IMMEDIATE COAST/OUTER ISLAND. THE TIME FRAME FOR THIS WOULD BE MONDAY NIGHT INTO TUESDAY. THE 12Z ECWMF RUN MATCHED UP W/ITS 00Z RUN OF BRINGING THE SUB-TROPICAL SYSTEM MME AND PASSING THE EAST OF NOVA SCOTIA. IF SCENARIO WERE TO TAKE PLACE, THE OUTER BANDS OF PRECIPITATION WOULD SKIRT THE IMMEDIATE COAST AND THE OUTER ISLANDS. THE 12Z RUN OF THE GFS AND GEM GLOBAL KEEP THE LOW FURTHER SOUTH AND EAST W/THE NEW ENGLAND REGION STAYING ON THE DRY SIDE. ATTM, DECIDED TO USE A BLEND OF ALL 3 AS SOME THE GFS ENSEMBLE MEMBERS SHOW A TRACK SIMILAR TO THE ECMWF. THEREFORE, KEPT THE MAJORITY OF THE CWA DRY INTO TUESDAY AND HUNG ON TO A 20-30% CHC FOR RAIN ALONG THE IMMEDIATE COAST AND THE OUTER ISLANDS MONDAY NIGHT INTO TUESDAY. WEDNESDAY AND THURSDAY APPEAR TO BE DRY AS HIGH PRES RE-ESTABLISHES ITSELF OVER THE NORTHEASTERN US. DAYTIME TEMPERATURES WILL CONTINUE TO BE AOA NORMAL. DECIDED TO BLEND THE BCMOS INCLUDING THE ECMWF FOR THE OVERNIGHT LOWS AS THE GMOS TEMPERATURES LOOK TO BE TOO COLD GIVEN THE ESTABLISHED PATTERN IN PLACE. && .AVIATION /22Z THURSDAY THROUGH TUESDAY/... NEAR TERM: MOSTLY OVC035 AT THE TAF SITES THIS EVENING. THE NORTHERN TAF SITES SHOULD REMAIN VFR WITH THE CLOUDS BECOMING SCT OVERNIGHT. KBGR AND KBHB MAY GO BACK DOWN TO MVFR FOR A TIME LATER THIS EVENING BEFORE LIFTING TO VFR EARLY MONDAY MORNING. SHORT TERM: VFR RUNNING RIGHT INTO MONDAY. && .MARINE... NEAR TERM: LIGHT WINDS UNDER 15 KTS AND SEAS MOSTLY AROUND 2 FT ON THE COASTAL WATERS AND 1 FOOT ON THE INTRA-COASTAL WATERS THROUGH THE PERIOD. SHORT TERM: NO HEADLINES EXPECTED. AS WINDS ADD SEAS ARE FCST TO REMAIN BELOW SCA THRESHOLDS. WE AREA TALKING WINDS OF 10 KTS RIGHT INTO MONDAY. THERE IS THE POTENTIAL FOR A SWELL TO BE GENERATED BY MONDAY FROM THE LOW APCHG FROM THE S. ADJUSTED THE WAVE HEIGHTS TO ACCOUNT FOR THIS POSSIBILITY. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...NONE. MARINE...NONE. && $$ NEAR TERM...CB/MCW SHORT TERM...FITZSIMMONS LONG TERM...FITZSIMMONS AVIATION...CB/MCW/FITZSIMMONS MARINE...CB/MCW/FITZSIMMONS
AREA FORECAST DISCUSSION...UPDATED
NWS MARQUETTE MI
138 PM EDT THU SEP 26 2013 .UPDATE... ISSUED AT 1249 PM EDT THU SEP 26 2013 CHANGES THIS HOUR: FOG HAS FINALLY GIVEN WAY DOWN TOWARDS KMNM THIS HOUR...WITH JUST A FEW CIRRUS FILTERING THE SUNSHINE. WILL EXTEND FOG MENTION OVER NORTHERN GREEN BAY...BUT OTHERWISE LITTLE CHANGES ARE NEEDED TO THE AFTERNOON FORECAST. TEMPERATURES RUNNING A LITTLE BEHIND PREVIOUS FORECAST GIVEN THIS LATE CLEAR OUT...BUT DO EXPECT THEM TO REBOUND NICELY WITH NEARLY FULL SUN THIS AFTERNOON. UPDATE ISSUED AT 937 AM EDT THU SEP 26 2013 CHANGES THIS HOUR: WILL EXTEND FOG ANOTHER HOUR GIVEN EARLY MORNING VISIBLE SATELLITE TRENDS WHICH SHOW A /VERY/ SLOW BURNING OFF PROCESS BEGINNING. OTHERWISE...HAVE LOWERED AFTERNOON DEWPOINTS A TAD BASED ON DRY AIRMASS CENTERING ITSELF OVERHEAD THIS AFTERNOON...WITH NO OTHER SIGNIFICANT CHANGES NECESSARY. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 406 AM EDT THU SEP 26 2013 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW A STAGNANT UPR FLOW OVER THE CONUS WITH UPR RDG OVER THE GREAT LKS SANDWICHED BTWN SLOW MOVING CLOSED LO OFF THE CANADIAN MARITIMES AND A DEEPENING TROF OVER THE WRN STATES. SFC HI PRES REMAINS ANCHORED IN QUEBEC... WITH RDG AXIS EXTENDING SWWD INTO THE UPR LKS. ALTHOUGH ABUNDANT MID LVL DRY AIR ABOVE SHARP SUBSIDENCE INVRN NEAR H9 SHOWN ON THE 00Z GRB/APX RAOBS IS BRINGING DRY WX...EFFICIENT NOCTURNAL COOLING HAS ALLOWED FOG TO FORM OVER MAINLY THE SCENTRAL COUNTIES AND THE KEWEENAW WHERE LGT E-SE FLOW ARND SFC HI PRES IS UPSLOPING OFF THE LKS. BUT IN CONTRAST TO LAST NGT...ADVECTION OF VERY DRY NEAR SFC AIRMASS SHOWN ON THE 00Z APX RAOB /PWAT 0.30 INCH/ IS TENDING TO LIMIT THE COVERAGE OF THE THICKER FOG. MAIN FCST CONCERNS IN THE SHORT TERM ARE FOG TRENDS AND TEMPS AS WELL AS THE POTENTIAL FOR MORE FOG FORMATION TNGT. EARLY THIS MRNG/TDAY...MAIN LIMITATION TO WDSPRD DENSE FOG EARLY THIS MRNG WL BE THE ADVECTION OF THE DRIER LLVL AIR SHOWN ON THE 00Z APX RAOB. SHORT TERM MODEL FCSTS SHOW THIS DRIER H95-9 AIR BLO THE SUBSIDENCE INVRN OVERSRREADING UPR MI EARLY THIS MRNG...COUNTERING TO SOME EXTENT THE IMPACT OF NOCTURNAL COOLING UNDER THE MID LVL DRY AIR. WL MAINTAIN A MENTION OF AREAS OF FOG UNTIL 13Z OVER THE SCENTRAL WITH FVRBL UPSLOPE WIND COMPONENT. AWAY FM THIS AREA...EXPECT NOTHING MORE THAN PATCHY FOG. DOWNSLOPE NATURE OF THE LLVL FLOW WL LIKELY KEEP MUCH FOG FM DVLPG NEAR LK SUP AND OVER THE FAR W ARND IWD. ISSUED SPS FOR THE SCENTRAL COUNTIES TO COVER LOCALLY DENSE FOG IN THIS AREA THRU SUNRISE...BUT AN ADVY WL NOT BE NECESSARY. ONCE ANY FOG BURNS OFF SOON AFTER SUNRISE...EXPECT MOSUNNY SKIES. WITH H85 TEMPS FCST UP TO 17C OVER THE W...MAX TEMPS THERE SHOULD TOP OUT IN THE 70S AWAY FM SOME MODERATION ON MAINLY THE E SIDE OF THE KEWEENAW IN LLVL SE FLOW. THIS SE FLOW WL TEND TO LIMIT THE DIURNAL TEMP RISE OVER THE SE COUNTIES. TNGT...THE UPR RDG AXIS IS FCST TO DRIFT ONLY SLOWLY TO THE E...WITH SFC HI OVER QUEBEC DRIFTING S INTO NEW ENGLAND. WITH FALLING MSLP IN THE PLAINS ASSOCIATED WITH SHRTWV LIFTING OUT OF THE WRN TROF...THE PRES GRADIENT/SLY FLOW IS PROGGED TO SHARPEN OVER MAINLY WRN UPR MI. THIS INCRSG S WIND IN CONCERT WITH FCST INCRSG PWAT WL RESTRICT THE DIURNAL TEMP FALL IN THIS AREA...SO TENDED TOWARD THE WARM SIDE OF GUIDANCE FOR MIN TEMPS OVER THE FAR W FM IWD INTO THE KEWEENAW. A FLATTER PRES GRADIENT/PWAT FCST AOB 0.50 INCH CLOSER TO THE SFC HI TO THE E WL SUPPORT LOWER TEMPS OVER THE INTERIOR E HALF...AND FCST LO TEMPS CLOSER TO THE LO END OF GUIDANCE IN THIS AREA. BUT SOMEWHAT STRONGER H925 WINDS UP TO 20KTS FCST IN THIS AREA WL LIKELY KEEP THE LOWS A BIT HIER THAN OBSVD THIS MRNG. WITH THE S WIND OFF LK MI... EXPECT MORE FOG TO FORM IN THIS AREA. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 406 AM EDT THU SEP 26 2013 FRIDAY WILL BE THE LAST COMPLETELY DRY DAY ACROSS THE CWA AS THE HIGH PRESSURE RIDGE THAT HAS BEEN INFLUENCING OUR WEATHER SLIDES SOUTHEAST INTO THE ATLANTIC STATES. AT THE SAME TIME...THE UPPER TROUGH CURRENTLY OVER THE WESTERN CONUS WILL EJECT OUT OF THE ROCKIES AND INTO THE CENTRAL AND NORTHERN PLAINS. A SHORTWAVE EXITING THIS UPPER TROUGH WILL MOVE NORTHEAST THROUGH THE CANADIAN PRAIRIES WITH AN ASSOCIATED SURFACE LOW THAT LEAVE AN ELONGATED SURFACE TROUGH STRETCHING SOUTH THROUGH MINNESOTA AND INTO THE CENTRAL PLAINS. SINCE THAT WILL BE THE MAIN FOCUS OF THE PRECIPITATION ON FRIDAY AND THE AREA STILL UNDER THE DRY AIR OF THE HIGH...SHOULD SEE ANOTHER MOSTLY SUNNY DAY ACROSS THE CWA. LATE IN THE AFTERNOON...COULD SEE SOME MID-HIGH CLOUDS AFFECTING WESTERN UPPER MICHIGAN. WITH THE SUNSHINE...SHOULD SEE ANOTHER DAY OF ABOVE NORMAL HIGHS WITH TEMPERATURES IN THE UPPER 60S TO MIDDLE 70S. IT SHOULD BE A LITTLE BREEZY ON FRIDAY DUE TO THE INCREASING PRESSURE GRADIENT BETWEEN THE HIGH AND THE APPROACHING TROUGH...ESPECIALLY OVER THE WEST WHERE THERE COULD BE GUSTS TO 25-30MPH. EXPECT BREEZY CONDITIONS TO CONTINUE AT TIMES FRIDAY NIGHT INTO SATURDAY UNTIL THE FRONT MOVES THROUGH. THIS DRY AIR WILL REMAIN THROUGH FRIDAY NIGHT AND INTO SATURDAY MORNING...WITH ONLY A FEW SHOWERS BRUSHING FAR WESTERN LAKE SUPERIOR DURING THAT TIME. THEN...AS THE UPPER TROUGH EJECTS OUT OF THE FOUR CORNERS REGION FRIDAY NIGHT...IT PULLS THE ENTIRE UPPER TROUGH WITH IT AND THROUGH THE UPPER GREAT LAKES REGION THROUGH SUNDAY. IN ADDITION...A SECONDARY LOW WILL DEVELOP ALONG THE TROUGH NEAR WESTERN LAKE SUPERIOR AND THE MN ARROWHEAD AS THE RIGHT REAR OF THE UPPER JET SLIDES NORTHEAST THROUGH THE AREA. THIS WILL ALLOW A LINE OF SHOWERS ORIENTATED NORTH-SOUTH ALONG AND BEHIND THE TROUGH TO MOVE EAST-NORTHEAST ACROSS UPPER MICHIGAN. AS HAS BEEN THE CASE OVER THE LAST SEVERAL NIGHT...THE GFS REMAINS THE FASTEST WITH THE ARRIVAL OF THE TROUGH/SHOWERS...WHILE THE GEM/ECMWF ARE MORE CONSISTENT WITH THE SLOWER ARRIVAL. THE NAM ALSO FOLLOWS ALONG WITH THE FASTER ARRIVAL SHOWN IN THE GFS. SINCE THERE IS AN EVEN SPLIT IN ARRIVAL TIMES AND ONLY 50-75MI SPREAD...WILL SPLIT THE DIFFERENCE AT THIS POINT AND HAVE THE WESTERN THIRD/HALF OF UPPER MICHIGAN SEEING RAIN BY SUNSET AND THEN IT SPREADING ACROSS THE REST OF THE CWA SATURDAY EVENING. WITH THE DIFFERENCES IN SPEED...ALSO FOLLOWED THE SIMILAR IDEA FOR THE BACK SIDE OF THE RAIN OVERNIGHT SATURDAY. STILL APPEARS LIKE A DECENT OPPORTUNITY FOR A QUARTER INCH OF RAIN OVER MUCH OF THE CWA...ALTHOUGH IT WILL LIKELY FALL IN A 2-3HR PERIOD. FINALLY...THUNDER POTENTIAL STILL LOOKS TO BE VERY LIMITED...ESPECIALLY WITH MUCH OF THE RAIN EXPECTED TO BE POST-FRONTAL. THERE ARE A COUPLE SMALL POCKETS OF 700-500MB LAPSE RATES APPROACHING 6.5C/KM AHEAD OF THE FRONT AND SIMILAR POCKETS OF MUCAPE NEAR 250 J/KG. IF A RUMBLE OF THUNDER OCCURS...BELIEVE IT WOULD BE IN THE WESTERN U.P. IN THE AFTERNOON. BUT...SINCE COVERAGE SHOULD BE VERY ISOLATED...OPTED TO REMOVE THE SLIGHT CHANCE OF THUNDER. WEAK UPPER RIDGE WILL QUICKLY BUILD IN ON SUNDAY AFTERNOON AND REMAIN INTO MONDAY. THIS WILL LEAD TO ANOTHER DRY PERIOD OF WEATHER. THERE MAY BE A SOME POST-FRONTAL CLOUDS SUNDAY AFTERNOON AS A POCKET OF COOLER TEMPERATURES ALOFT MOVE THROUGH. ECMWF/GEM SEEM TO LIKE THAT IDEA...WHILE GFS KEEPS THINGS CLEAR. SINCE THAT MOISTURE AND COOLER AIR WILL BE QUICKLY PULLING OUT ON SUNDAY...WITH FOLLOW THE GENERAL IDEA OF DECREASING CLOUDS ON SUNDAY. HIGHS WILL BE COOLER ON SUNDAY WITH THAT COLD POCKET OF AIR...BUT STILL THINK THEY WILL END UP IN THE LOWER-MID 60S IN MOST LOCATIONS (WHICH IS NORMAL FOR THIS TIME OF YEAR). TEMPERATURES SHOULD WARM BACK ABOVE NORMAL ON MONDAY WITH HIGHS IN THE UPPER 60S AND LOWER 70S...AS 850MB TEMPERATURES PUSH BACK INTO THE LOWER TEENS. CONUS LOOKS TO COME UNDER ZONAL FLOW FOR TUESDAY AND PART OF WEDNESDAY...AS THE UPPER JET RUNS WEST-EAST ACROSS THE NORTHERN ROCKIES. THIS SHOULD KEEP THE MAIN SYNOPTIC FEATURES LOCKED IN CANADA AND POSSIBLY JUST BRUSHING THE AREA AT TIMES MONDAY NIGHT THROUGH TUESDAY NIGHT. THIS WILL ALSO KEEP THE AREA UNDER ABOVE && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 132 PM EDT THU SEP 26 2013 SUMMARY: HIGH PRESSURE OVER QUEBEC WILL GRADUALLY SETTLE SOUTH THROUGH THE COMING TAF PERIOD...ALLOWING SOUTHERLY WINDS TO INCREASE. OTHERWISE...WEATHER CONDITIONS ARE EXPECTED TO REMAIN QUIET THROUGH FRIDAY AFTERNOON. RESTRICTIONS: GENERALLY VFR THROUGH THE FORECAST PERIOD. ONLY THREAT OF RESTRICTIONS WILL COME IN THE FORM OF FOG POTENTIAL TONIGHT. INHERITED IDEA OF SOME LIGHT FOG SAW LOOKS GOOD...WITH TOO MUCH MIXING TO THE WEST TO ALLOW A REDEVELOPMENT OF FOG. GUT FEELING IS THAT IF FOG/STRATUS DOES REDEVELOP...IT WILL BE THINNDER AND OCCUR FURTHER EAST THAN LAST NIGHT...AND THUS IS NOT EXPECTED TO HAVE AS LARGE OF AN IMPACT AS IT DID THIS MORNING. WINDS: SOUTHERLY WINDS 5-10KTS WILL DIMINISH TO AROUND 5KTS FOR THE OVERNIGHT HOURS BEFORE STRENGTHENING TO 10G18KTS FOR THE DAY ON FRIDAY. LLWS: GIVEN THE STRENGTHENING GRADIENT THIS EVENING...EXPECT SOUTHERLY WINDS JUST ABOVE THE SURFACE TO INCREASE TO 25-30KTS... PRODUCING A PERIOD OF LLWS GIVEN EXPECTED STABLE PROFIILES IN THE LOW LEVELS. THIS WILL MIX OUT FRIDAY MORNING. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 406 AM EDT THU SEP 26 2013 HIGH PRESSURE OVER WESTERN QUEBEC WILL CONTINUE TO DOMINATE THE WEATHER FOR TODAY...ALTHOUGH IT WILL BEGIN TO SLIDE SOUTHEAST TONIGHT. BEFORE THIS OCCURS...THERE IS AN AREA OF FOG (LOCALLY DENSE) OVER THE WESTERN LAKE EARLY THIS MORNING AND EXPECT THAT TO DIMINISH THIS MORNING AS DRIER AIR SLIDES IN FROM THE SOUTHEAST. MEANWHILE...A LOW PRESSURE SYSTEM MOVING NORTHEAST OUT OF THE NORTHERN PLAINS TODAY WILL LINGER A TROUGH EASTERN DAKOTAS TONIGHT AND THEN SLOWLY MOVE EAST ACROSS MINNESOTA ON FRIDAY. AS THIS OCCURS...THE PRESSURE GRADIENT AND THUS SOUTHERLY WINDS WILL INCREASE OVER LAKE SUPERIOR ON FRIDAY. THESE STRONGER WINDS...TO 25KTS...WILL CONTINUE FRIDAY NIGHT AND SATURDAY UNTIL THE TROUGH MOVES THROUGH LATE SATURDAY AFTERNOON AND EVENING. BEHIND THE TROUGH...THERE COULD BE A BRIEF PERIOD OF STRONGER WESTERLY WINDS TO 25KTS OVER NORTH CENTRAL LAKE SUPERIOR OVERNIGHT SATURDAY NIGHT INTO EARLY SUNDAY MORNING. WEAK HIGH PRESSURE WILL BUILD IN TO THE UPPER && .MQT WATCHES/WARNINGS/ADVISORIES... MI...NONE. LS...NONE. LM...NONE. && $$ UPDATE...ARNOTT SHORT TERM...KC LONG TERM...SRF AVIATION...ARNOTT MARINE...SRF
AREA FORECAST DISCUSSION...UPDATED
NWS MARQUETTE MI
1256 PM EDT THU SEP 26 2013 .UPDATE... ISSUED AT 1249 PM EDT THU SEP 26 2013 CHANGES THIS HOUR: FOG HAS FINALLY GIVEN WAY DOWN TOWARDS KMNM THIS HOUR...WITH JUST A FEW CIRRUS FILTERING THE SUNSHINE. WILL EXTEND FOG MENTION OVER NORTHERN GREEN BAY...BUT OTHERWISE LITTLE CHANGES ARE NEEDED TO THE AFTERNOON FORECAST. TEMPERATURES RUNNING A LITTLE BEHIND PREVIOUS FORECAST GIVEN THIS LATE CLEAR OUT...BUT DO EXPECT THEM TO REBOUND NICELY WITH NEARLY FULL SUN THIS AFTERNOON. UPDATE ISSUED AT 937 AM EDT THU SEP 26 2013 CHANGES THIS HOUR: WILL EXTEND FOG ANOTHER HOUR GIVEN EARLY MORNING VISIBLE SATELLITE TRENDS WHICH SHOW A /VERY/ SLOW BURNING OFF PROCESS BEGINNING. OTHERWISE...HAVE LOWERED AFTERNOON DEWPOINTS A TAD BASED ON DRY AIRMASS CENTERING ITSELF OVERHEAD THIS AFTERNOON...WITH NO OTHER SIGNIFICANT CHANGES NECESSARY. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 406 AM EDT THU SEP 26 2013 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW A STAGNANT UPR FLOW OVER THE CONUS WITH UPR RDG OVER THE GREAT LKS SANDWICHED BTWN SLOW MOVING CLOSED LO OFF THE CANADIAN MARITIMES AND A DEEPENING TROF OVER THE WRN STATES. SFC HI PRES REMAINS ANCHORED IN QUEBEC... WITH RDG AXIS EXTENDING SWWD INTO THE UPR LKS. ALTHOUGH ABUNDANT MID LVL DRY AIR ABOVE SHARP SUBSIDENCE INVRN NEAR H9 SHOWN ON THE 00Z GRB/APX RAOBS IS BRINGING DRY WX...EFFICIENT NOCTURNAL COOLING HAS ALLOWED FOG TO FORM OVER MAINLY THE SCENTRAL COUNTIES AND THE KEWEENAW WHERE LGT E-SE FLOW ARND SFC HI PRES IS UPSLOPING OFF THE LKS. BUT IN CONTRAST TO LAST NGT...ADVECTION OF VERY DRY NEAR SFC AIRMASS SHOWN ON THE 00Z APX RAOB /PWAT 0.30 INCH/ IS TENDING TO LIMIT THE COVERAGE OF THE THICKER FOG. MAIN FCST CONCERNS IN THE SHORT TERM ARE FOG TRENDS AND TEMPS AS WELL AS THE POTENTIAL FOR MORE FOG FORMATION TNGT. EARLY THIS MRNG/TDAY...MAIN LIMITATION TO WDSPRD DENSE FOG EARLY THIS MRNG WL BE THE ADVECTION OF THE DRIER LLVL AIR SHOWN ON THE 00Z APX RAOB. SHORT TERM MODEL FCSTS SHOW THIS DRIER H95-9 AIR BLO THE SUBSIDENCE INVRN OVERSRREADING UPR MI EARLY THIS MRNG...COUNTERING TO SOME EXTENT THE IMPACT OF NOCTURNAL COOLING UNDER THE MID LVL DRY AIR. WL MAINTAIN A MENTION OF AREAS OF FOG UNTIL 13Z OVER THE SCENTRAL WITH FVRBL UPSLOPE WIND COMPONENT. AWAY FM THIS AREA...EXPECT NOTHING MORE THAN PATCHY FOG. DOWNSLOPE NATURE OF THE LLVL FLOW WL LIKELY KEEP MUCH FOG FM DVLPG NEAR LK SUP AND OVER THE FAR W ARND IWD. ISSUED SPS FOR THE SCENTRAL COUNTIES TO COVER LOCALLY DENSE FOG IN THIS AREA THRU SUNRISE...BUT AN ADVY WL NOT BE NECESSARY. ONCE ANY FOG BURNS OFF SOON AFTER SUNRISE...EXPECT MOSUNNY SKIES. WITH H85 TEMPS FCST UP TO 17C OVER THE W...MAX TEMPS THERE SHOULD TOP OUT IN THE 70S AWAY FM SOME MODERATION ON MAINLY THE E SIDE OF THE KEWEENAW IN LLVL SE FLOW. THIS SE FLOW WL TEND TO LIMIT THE DIURNAL TEMP RISE OVER THE SE COUNTIES. TNGT...THE UPR RDG AXIS IS FCST TO DRIFT ONLY SLOWLY TO THE E...WITH SFC HI OVER QUEBEC DRIFTING S INTO NEW ENGLAND. WITH FALLING MSLP IN THE PLAINS ASSOCIATED WITH SHRTWV LIFTING OUT OF THE WRN TROF...THE PRES GRADIENT/SLY FLOW IS PROGGED TO SHARPEN OVER MAINLY WRN UPR MI. THIS INCRSG S WIND IN CONCERT WITH FCST INCRSG PWAT WL RESTRICT THE DIURNAL TEMP FALL IN THIS AREA...SO TENDED TOWARD THE WARM SIDE OF GUIDANCE FOR MIN TEMPS OVER THE FAR W FM IWD INTO THE KEWEENAW. A FLATTER PRES GRADIENT/PWAT FCST AOB 0.50 INCH CLOSER TO THE SFC HI TO THE E WL SUPPORT LOWER TEMPS OVER THE INTERIOR E HALF...AND FCST LO TEMPS CLOSER TO THE LO END OF GUIDANCE IN THIS AREA. BUT SOMEWHAT STRONGER H925 WINDS UP TO 20KTS FCST IN THIS AREA WL LIKELY KEEP THE LOWS A BIT HIER THAN OBSVD THIS MRNG. WITH THE S WIND OFF LK MI... EXPECT MORE FOG TO FORM IN THIS AREA. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 406 AM EDT THU SEP 26 2013 FRIDAY WILL BE THE LAST COMPLETELY DRY DAY ACROSS THE CWA AS THE HIGH PRESSURE RIDGE THAT HAS BEEN INFLUENCING OUR WEATHER SLIDES SOUTHEAST INTO THE ATLANTIC STATES. AT THE SAME TIME...THE UPPER TROUGH CURRENTLY OVER THE WESTERN CONUS WILL EJECT OUT OF THE ROCKIES AND INTO THE CENTRAL AND NORTHERN PLAINS. A SHORTWAVE EXITING THIS UPPER TROUGH WILL MOVE NORTHEAST THROUGH THE CANADIAN PRAIRIES WITH AN ASSOCIATED SURFACE LOW THAT LEAVE AN ELONGATED SURFACE TROUGH STRETCHING SOUTH THROUGH MINNESOTA AND INTO THE CENTRAL PLAINS. SINCE THAT WILL BE THE MAIN FOCUS OF THE PRECIPITATION ON FRIDAY AND THE AREA STILL UNDER THE DRY AIR OF THE HIGH...SHOULD SEE ANOTHER MOSTLY SUNNY DAY ACROSS THE CWA. LATE IN THE AFTERNOON...COULD SEE SOME MID-HIGH CLOUDS AFFECTING WESTERN UPPER MICHIGAN. WITH THE SUNSHINE...SHOULD SEE ANOTHER DAY OF ABOVE NORMAL HIGHS WITH TEMPERATURES IN THE UPPER 60S TO MIDDLE 70S. IT SHOULD BE A LITTLE BREEZY ON FRIDAY DUE TO THE INCREASING PRESSURE GRADIENT BETWEEN THE HIGH AND THE APPROACHING TROUGH...ESPECIALLY OVER THE WEST WHERE THERE COULD BE GUSTS TO 25-30MPH. EXPECT BREEZY CONDITIONS TO CONTINUE AT TIMES FRIDAY NIGHT INTO SATURDAY UNTIL THE FRONT MOVES THROUGH. THIS DRY AIR WILL REMAIN THROUGH FRIDAY NIGHT AND INTO SATURDAY MORNING...WITH ONLY A FEW SHOWERS BRUSHING FAR WESTERN LAKE SUPERIOR DURING THAT TIME. THEN...AS THE UPPER TROUGH EJECTS OUT OF THE FOUR CORNERS REGION FRIDAY NIGHT...IT PULLS THE ENTIRE UPPER TROUGH WITH IT AND THROUGH THE UPPER GREAT LAKES REGION THROUGH SUNDAY. IN ADDITION...A SECONDARY LOW WILL DEVELOP ALONG THE TROUGH NEAR WESTERN LAKE SUPERIOR AND THE MN ARROWHEAD AS THE RIGHT REAR OF THE UPPER JET SLIDES NORTHEAST THROUGH THE AREA. THIS WILL ALLOW A LINE OF SHOWERS ORIENTATED NORTH-SOUTH ALONG AND BEHIND THE TROUGH TO MOVE EAST-NORTHEAST ACROSS UPPER MICHIGAN. AS HAS BEEN THE CASE OVER THE LAST SEVERAL NIGHT...THE GFS REMAINS THE FASTEST WITH THE ARRIVAL OF THE TROUGH/SHOWERS...WHILE THE GEM/ECMWF ARE MORE CONSISTENT WITH THE SLOWER ARRIVAL. THE NAM ALSO FOLLOWS ALONG WITH THE FASTER ARRIVAL SHOWN IN THE GFS. SINCE THERE IS AN EVEN SPLIT IN ARRIVAL TIMES AND ONLY 50-75MI SPREAD...WILL SPLIT THE DIFFERENCE AT THIS POINT AND HAVE THE WESTERN THIRD/HALF OF UPPER MICHIGAN SEEING RAIN BY SUNSET AND THEN IT SPREADING ACROSS THE REST OF THE CWA SATURDAY EVENING. WITH THE DIFFERENCES IN SPEED...ALSO FOLLOWED THE SIMILAR IDEA FOR THE BACK SIDE OF THE RAIN OVERNIGHT SATURDAY. STILL APPEARS LIKE A DECENT OPPORTUNITY FOR A QUARTER INCH OF RAIN OVER MUCH OF THE CWA...ALTHOUGH IT WILL LIKELY FALL IN A 2-3HR PERIOD. FINALLY...THUNDER POTENTIAL STILL LOOKS TO BE VERY LIMITED...ESPECIALLY WITH MUCH OF THE RAIN EXPECTED TO BE POST-FRONTAL. THERE ARE A COUPLE SMALL POCKETS OF 700-500MB LAPSE RATES APPROACHING 6.5C/KM AHEAD OF THE FRONT AND SIMILAR POCKETS OF MUCAPE NEAR 250 J/KG. IF A RUMBLE OF THUNDER OCCURS...BELIEVE IT WOULD BE IN THE WESTERN U.P. IN THE AFTERNOON. BUT...SINCE COVERAGE SHOULD BE VERY ISOLATED...OPTED TO REMOVE THE SLIGHT CHANCE OF THUNDER. WEAK UPPER RIDGE WILL QUICKLY BUILD IN ON SUNDAY AFTERNOON AND REMAIN INTO MONDAY. THIS WILL LEAD TO ANOTHER DRY PERIOD OF WEATHER. THERE MAY BE A SOME POST-FRONTAL CLOUDS SUNDAY AFTERNOON AS A POCKET OF COOLER TEMPERATURES ALOFT MOVE THROUGH. ECMWF/GEM SEEM TO LIKE THAT IDEA...WHILE GFS KEEPS THINGS CLEAR. SINCE THAT MOISTURE AND COOLER AIR WILL BE QUICKLY PULLING OUT ON SUNDAY...WITH FOLLOW THE GENERAL IDEA OF DECREASING CLOUDS ON SUNDAY. HIGHS WILL BE COOLER ON SUNDAY WITH THAT COLD POCKET OF AIR...BUT STILL THINK THEY WILL END UP IN THE LOWER-MID 60S IN MOST LOCATIONS (WHICH IS NORMAL FOR THIS TIME OF YEAR). TEMPERATURES SHOULD WARM BACK ABOVE NORMAL ON MONDAY WITH HIGHS IN THE UPPER 60S AND LOWER 70S...AS 850MB TEMPERATURES PUSH BACK INTO THE LOWER TEENS. CONUS LOOKS TO COME UNDER ZONAL FLOW FOR TUESDAY AND PART OF WEDNESDAY...AS THE UPPER JET RUNS WEST-EAST ACROSS THE NORTHERN ROCKIES. THIS SHOULD KEEP THE MAIN SYNOPTIC FEATURES LOCKED IN CANADA AND POSSIBLY JUST BRUSHING THE AREA AT TIMES MONDAY NIGHT THROUGH TUESDAY NIGHT. THIS WILL ALSO KEEP THE AREA UNDER ABOVE && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 725 AM EDT THU SEP 26 2013 LINGERING FOG/IFR TO VLIFR CONDITIONS WL GIVE WAY TO VFR CONDITIONS BY MID MRNG WITH THE ONSET OF DAYTIME HEATING THAT MIXES OUT THE FOG. THEN VFR WX WL PREVAIL AT ALL 3 TAF SITES THRU AT LEAST 06Z TNGT. A STRONGER S WIND ABOVE RADIATION INVRN TNGT THAT WL CAUSE LLWS AT IWD SHOULD PREVENT MORE FOG FORMATION AT IWD AND CMX. BUT AT SAW...UPSLOPE NATURE OF THE S WIND OFF LK MI AND SOMEWHAT WEAKER FLOW THAT WL ALLOW MORE EFFICIENT RADIATIONAL COOLING WL BE SUFFICIENT FOR A BETTER CHC OF RADIATION FOG AT THAT LOCATION. IF THE WINDS ARE LIGHTER THAN EXPECTED AT SAW...IFR CONDITIONS MIGHT BE && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 406 AM EDT THU SEP 26 2013 HIGH PRESSURE OVER WESTERN QUEBEC WILL CONTINUE TO DOMINATE THE WEATHER FOR TODAY...ALTHOUGH IT WILL BEGIN TO SLIDE SOUTHEAST TONIGHT. BEFORE THIS OCCURS...THERE IS AN AREA OF FOG (LOCALLY DENSE) OVER THE WESTERN LAKE EARLY THIS MORNING AND EXPECT THAT TO DIMINISH THIS MORNING AS DRIER AIR SLIDES IN FROM THE SOUTHEAST. MEANWHILE...A LOW PRESSURE SYSTEM MOVING NORTHEAST OUT OF THE NORTHERN PLAINS TODAY WILL LINGER A TROUGH EASTERN DAKOTAS TONIGHT AND THEN SLOWLY MOVE EAST ACROSS MINNESOTA ON FRIDAY. AS THIS OCCURS...THE PRESSURE GRADIENT AND THUS SOUTHERLY WINDS WILL INCREASE OVER LAKE SUPERIOR ON FRIDAY. THESE STRONGER WINDS...TO 25KTS...WILL CONTINUE FRIDAY NIGHT AND SATURDAY UNTIL THE TROUGH MOVES THROUGH LATE SATURDAY AFTERNOON AND EVENING. BEHIND THE TROUGH...THERE COULD BE A BRIEF PERIOD OF STRONGER WESTERLY WINDS TO 25KTS OVER NORTH CENTRAL LAKE SUPERIOR OVERNIGHT SATURDAY NIGHT INTO EARLY SUNDAY MORNING. WEAK HIGH PRESSURE WILL BUILD IN TO THE UPPER && .MQT WATCHES/WARNINGS/ADVISORIES... MI...NONE. LS...NONE. LM...NONE. && $$ UPDATE...ARNOTT SHORT TERM...KC LONG TERM...SRF AVIATION...KC MARINE...SRF
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1258 PM EDT THU SEP 26 2013 .SYNOPSIS... AN UPPER LEVEL WILL MOVE OFF THE CAROLINA COAST THIS AFTERNOON. HIGH PRESSURE WILL BUILD IN FROM THE NORTH ON FRIDAY INTO SUNDAY. && .NEAR TERM /TODAY THROUGH TONIGHT/... AS OF 1000 AM THURSDAY... AN UPPER LEVEL LOW CONTINUES TO ROTATE OVER THE CAROLINAS THIS MORNING AND THE CURRENT RUN OF THE RAP MODELS SHOWS SOME STRONGER POCKETS OF VORTICITY COMING OUT OF SOUTHERN VA AND APPROACHING OUR NORTHERN LOCALES. FURTHER INSPECTION OF SATELLITE AND RADAR DATA SHOWS SOME LIGHT SHOWERS TRYING TO GAIN SOME COVERAGE AS THEY APPROACH ROXBORO OVER THE NEXT COUPLE OF HOURS. RAP MODEL SHOWS THE VORTICITY FIELD WEAKENING SO IT IS UNCLEAR WEATHER OR NOT THESE SHOWERS WILL HOLD TOGETHER BUT AT LEAST SOME SPRINKLES COULD BE POSSIBLE THROUGH EARLY AFTERNOON IN OUR NORTHERN COUNTIES. OTHERWISE THE REST OF THE CWA WILL REMAIN DRY AS DRIER AIR WORKS IN FROM THE SOUTHWEST AND THE LOW GRADUALLY MOVES OFF THE COAST. SOME MID LEVEL CLOUDS CAN BE EXPECTED ACROSS THE AREA THROUGH AT LEAST EARLY AFTERNOON WHICH MAY HELP TO KEEP TEMPERATURES DOWN A BIT. CURRENT OBS SHOW TEMPERATURES IN THE MID 60S TO NEAR 70 AND MAX TEMPS ARE EXPECTED TO TOP OUT IN THE MID 70S TO NEAR 80 IN THE SOUTHWEST WHERE CLEARING WILL OCCUR A LITTLE QUICKER. -ELLIS FOR TONIGHT: ON THE BACK SIDE OF THE DEPARTING MID LEVEL LOW... FLOW ALOFT BECOMES NORTHERLY... WHILE LOWER LEVEL FLOW STAYS A BIT STOUT FROM THE NORTHEAST AS THE MSLP GRADIENT TIGHTENS BETWEEN THE SURFACE LOW OFF THE FL/GA COAST AND THE INCOMING NARROW SURFACE HIGH PRESSURE RIDGE OVER THE EASTERN STATES. THIS FLOW WILL DRAW COOLER CANADIAN AIR INTO CENTRAL NC... WITH THICKNESSES BOTTOMING OUT AROUND 1365 M TOWARD MORNING. FORECAST SOUNDINGS SHOW A LOT OF DRYING THROUGH THE COLUMN AND DEEPLY STABLE AIR... SO EXPECT MOSTLY CLEAR SKIES... WITH A LIGHT NE WIND AS LOW LEVELS DECOUPLE. LOWS 52-56. -GIH && .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... AS OF 315 AM THURSDAY... THE AMPLIFIED MID LEVEL RIDGING FROM LA UP THROUGH MI AND TROUGHING OVER THE NW ATLANTIC WILL KEEP NC BENEATH A MODERATE NORTHERLY FLOW ALOFT... WHILE NEAR THE SURFACE... THE CANADIAN HIGH CENTERED OVER THE ST LAWRENCE VALLEY WILL CONTINUE TO NOSE NARROWLY SSW THROUGH CENTRAL/WRN NC. AS SURFACE PRESSURES REMAIN LOW OFF THE SOUTHEAST COAST... THE SOMEWHAT TIGHT MSLP GRADIENT WILL KEEP A STEADY NORTHEAST FLOW INTO NC... STRONGER OVER THE COASTAL PLAIN TRENDING WEAKER OVER THE TRIAD... MOST NOTABLE FROM LATE MORNING THROUGH AFTERNOON WITH A FEW GUSTS POSSIBLE. THE COLUMN STAYS FAIRLY DRY AND NEUTRAL TO SUBSIDING... HOWEVER MODELS SHOW A WAVE IN THE NORTHERLY STEERING FLOW DROPPING TO THE SOUTH FROM NEW ENGLAND LATE TONIGHT THROUGH THE NORTHEAST AND MIDATLANTIC STATES THROUGH FRIDAY INTO THE EVENING. THIS SHOULD SERVE TO REINFORCE THE COLD AIR ADVECTION AND BRING JUST ENOUGH 925-800 MB MOISTURE INTO THE AREA FOR PARTLY CLOUDY SKIES IN THE AFTERNOON AND POTENTIALLY INTO THE NIGHT TOO... AS THIS MOISTURE REMAINS TRAPPED BENEATH THE SUBSIDENCE INVERSION ALOFT. THICKNESSES ABOUT 15 M BELOW NORMAL WITH SOME SUNSHINE SUPPORTS HIGHS OF 73-78. LOWS 51-56 WITH FAIR SKIES. -GIH && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... AS OF 300 AM THURSDAY... SATURDAY AND SUNDAY: ALL INDICATORS SUGGEST THAT THE CLOSED UPPER LEVEL LOW OFF THE MID-ATLANTIC COAST WILL REMAIN OFFSHORE AND PROVE OF LITTLE CONSEQUENCE(AT LEAST OUTSIDE OF MARINE IMPACTS)...HELD AT BAY BY A HIGH-AMPLITUDE-LOW WAVELENGTH UPPER RIDGE AXIS BUILDING EASTWARD INTO THE CENTRAL/SOUTHERN APPALACHIANS. BETWEEN THESE TWO FEATURES...A COOL NORTHEASTERLY WIND WILL PREVAIL THROUGH THE WEEKEND...ANCHORED IN THE LOW-LEVELS BY A ~1025MB SURFACE HIGH EXTENDING DOWN THE MID-ATLANTIC SEABOARD. DRY AND SEASONABLY COOL WITH LOW-LEVEL THICKNESSES A GOOD 15-20M BELOW NORMAL SATURDAY AND SUNDAY MORNING. HIGHS 73 TO 78...WITH SUNDAY BEFORE THE WARMEST DAY OF THE TWO. LOWS IN THE LOWER TO MID 50S. MID/UPPER LEVEL SHORTWAVE TROUGH OVER THE ROCKIES WILL LIFT NORTHEASTWARD INTO THE UPPER GREAT LAKES AND SOUTHEAST CANADA THROUGH THE WEEKEND. AS THE BETTER SUPPORT ALOFT HEADS NORTH OF THE BORDER...AN ALREADY SCARCE PRECIP SHIELD ACCOMPANYING THE DISSIPATING COLD FRONT WILL LIKELY DRY OUT COMPLETELY ACROSS THE MID-ATLANTIC STATES ON MONDAY...WITH SERIOUS DOUBTS IF THE FRONT WILL EVER MAKE THIS FAR SOUTH. WILL LEAVE FORECAST DRY FOR NOW... BUT SOME SMALL/ISOLATED CHANCES MAY NEED TO BE ADDED AT A LATER TIME AS MODELS INDICATE THE POTENTIAL FOR SOME WEAK SOUTHERN STREAM ENERGY TO MOVE THROUGH THE SOUTHEAST US TUESDAY AND INTO WEDNESDAY. MEANWHILE...TEMPERATURES WILL STEADILY MODERATE THROUGH THE WEEK WITH LOW-LEVEL THICKNESSES CLIMBING A GOOD 20 TO 25 METERS ABOVE NORMAL BY MID-WEEK. HIGHS IN THE UPPER 70S TO MID LOWER 80S. LOWS IN THE MID 50S TO LOWER 60S. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... AS OF 100 PM THURSDAY... 24 HOUR TAF PERIOD: MODERATELY HIGH CONFIDENCE OF VFR CONDITIONS THROUGHOUT THE TAF PERIOD WITH THE EXCEPTION BEING SOME BRIEF SUB-VFR FOG OR LOW STRATUS...PREDOMINATELY IN THE EAST JUST BEFORE 12Z. WILL COVER THIS WITH A TEMPO IN THE TAFS AT RDU...FAY...AND KRWI. RH CROSS SECTIONS SHOW KRWI THE MOST LIKELY TO ENCOUNTER FOG/LOW STRATUS OVERNIGHT. OTHERWISE A PRETTY DRY FORECAST OUTSIDE OF A FEW ROGUE SPRINKLES IN THE TRIAD AND POSSIBLY RDU A BIT LATER THIS AFTERNOON AS A SHORTWAVE IMPULSE MOVES THROUGH THE NORTHERN TIER OF THE AREA. WINDS ARE EXPECTED TO BE GUSTY THIS AFTERNOON AND A FEW OBSERVATION SIGHTS ALREADY CONFIRMING THIS WITH 15-20 KNOTS THE MAXIMUM GUST. WITH SURFACE HIGH OVER THE MID-ATLANTIC AND NEW ENGLAND...WINDS WILL REMAIN NORTHEASTERLY THROUGH THE TAF PERIOD. LONG TERM: VERY DRY FORECAST FOR THE LONG TERM WITH VERY HIGH CONFIDENCE OF VFR CONDITIONS WITH THE EXCEPTION OF SOME BRIEF FOG IN THE LATE NIGHT/EARLY MORNING HOURS THROUGH THE WEEKEND. WINDS WILL REMAIN NORTHEASTERLY AND FAIRLY GUSTY IN THE AFTERNOON THROUGH SATURDAY. SUSTAINED WIND SPEEDS OF 10 KNOTS GUSTING 15 TO 20 KNOTS CAN BE EXPECTED BEFORE RELAXING ON SUNDAY AND BEYOND. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...ELLIS/HARTFIELD SHORT TERM...HARTFIELD LONG TERM...CBL AVIATION...ELLIS
AREA FORECAST DISCUSSION
NWS BISMARCK ND
101 PM CDT THU SEP 26 2013 .UPDATE... ISSUED AT 101 PM CDT THU SEP 26 2013 GRADIENT FLOW HAS NOT RESPONDED AS PREVIOUSLY EXPECTED. THE SURFACE LOW CONTINUES TO LIFT FARTHER NORTH INTO CANADA THAN HIGH PRESSURE CAN BUILD INTO WESTERN NORTH DAKOTA. THEREFORE...SUSTAINED SURFACE WINDS HAVE ONLY INCREASED TO AROUND 20 KNOTS EARLY THIS AFTERNOON. IN ADDITION...THE LATEST MODEL GUIDANCE CONTINUES TO BACK OFF ON WIND SPEEDS THIS AFTERNOON AS GRADIENT FLOW IS WEAKER THAN PREVIOUSLY EXPECTED. SUSTAINED WIND SPEEDS ARE EXPECTED TO BE UP TO 25 MPH THIS AFTERNOON WITH 35 MPH GUSTS...WHICH IS BELOW WIND ADVISORY CRITERIA. AS A RESULT...DECIDED TO CANCEL THE WIND ADVISORY FOR SOUTHWESTERN INTO NORTH CENTRAL NORTH DAKOTA THIS AFTERNOON. ALSO REMOVED AFTERNOON CONVECTION BASED ON CURRENT RADAR OBS/TRENDS. THE UPDATED PRODUCTS HAVE BEEN SENT. UPDATE ISSUED AT 949 AM CDT THU SEP 26 2013 SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WILL CONTINUE TO LIFT NORTH OUT OF NORTH CENTRAL NORTH DAKOTA THIS MORNING. NONE OF THIS ACTIVITY SHOULD BE SEVERE. ALL THUNDERSTORM ACTIVITY WILL BE OUT OF THE CWA BY THIS AFTERNOON. HIGH PRESSURE BUILDING INTO WESTERN NORTH DAKOTA AND LOW PRESSURE LIFTING INTO MANITOBA WILL GENERATE WINDY CONDITIONS ACROSS WESTERN AND NORTH CENTRAL NORTH DAKOTA THIS AFTERNOON. THE LATEST MODEL PROGS HAVE BACKED OFF ON THE SUSTAINED WIND SPEED FORECAST THIS AFTERNOON. HOWEVER...STILL THINK MARGINAL WIND ADVISORY CONDITIONS WILL BE ACHIEVED IN SOME SPOTS. THEREFORE...MAINTAINED THE CURRENT TEMPORAL AND AREAL RESOLUTION OF THE WIND ADVISORY THIS AFTERNOON. THE REMAINING FORECAST ELEMENTS ARE ON TRACK. THE UPDATED PRODUCTS HAVE BEEN SENT. UPDATE ISSUED AT 651 AM CDT THU SEP 26 2013 LOW PRESSURE SITUATED OVER CENTRAL NORTH DAKOTA WITH SCATTERED SHOWERS AND THUNDERSTORMS LIFTING FROM EAST CENTRAL INTO NORTHEAST NORTH DAKOTA...AND SHOWERS EXTENDING BACK INTO CENTRAL NORTH DAKOTA JUST AHEAD OF THE LOW. COLD NORTHERLY FLOW HAS MOVED INTO WESTERN NORTH DAKOTA WITH IFR CLOUDINESS SPREADING EAST ACROSS WESTERN NORTH DAKOTA. UPDATED WEATHER POPS TO MATCH WITH LATEST RADAR IMAGERY...AND EXTRAPOLATING NORTHEAST THROUGH THE MORNING. LIMITED MENTION OF THUNDER TO THE EAST CENTRAL AND FAR NORTH CENTRAL. INCREASED SKY COVER OVER THE WEST THROUGH THE MORNING TO ACCOUNT FOR THE LOW STRATUS. EXPECT THIS TO DISSIPATE BY LATE MORNING AND AFTERNOON WITH STRONG SUBSIDENCE MOVING INTO WESTERN NORTH DAKOTA. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 249 AM CDT THU SEP 26 2013 MAIN CONCERN TODAY WILL BE THUNDERSTORMS EARLY THIS MORNING FOLLOWED BY A WIND ADVISORY SOUTHWEST THROUGH NORTH CENTRAL. HAVE UTILIZED A BLEND OF ALL MODELS...BUT SPECIFICALLY THE HRRR FOR AREAL COVERAGE OF PRECIPITATION THIS MORNING AND NAM/GFS FOR THE WIND ADVISORY. THE LATEST WATER VAPOR IMAGERY ALONG WITH SPC MESOSCALE ANALYSIS CONTINUES TO SHOW THE H3 JET STREAK WORKING ITS WAY THROUGH WYOMING AND INTO SOUTH DAKOTA. UPPER DIVERGENCE FIELD ASSOCIATED WITH THE LEFT EXIT REGION CENTERED OVER CENTRAL/NORTHERN NORTH DAKOTA AS ISOLATED THUNDERSTORMS CONTINUE TO ESCALATE UPWARDS. SURFACE LOW PRESSURE IN SOUTHERN SOUTH DAKOTA WILL BEGIN TO MOVE NORTH ALONG A COLD FRONT WHICH IS NOW LOCATED FROM NEAR OXBOW SASKATCHEWAN...SOUTH TO MINOT AND INTO LEMMON SOUTH DAKOTA. AS THE JET STREAK AND UPPER DIVERGENCE FIELD SHIFT FURTHER NORTH THROUGH THE MORNING...THE SURFACE LOW WILL DEEPEN AS IT ENTERS SOUTHERN SASKATCHEWAN THIS AFTERNOON. A TIGHT PRESSURE GRADIENT WILL ENSUE...RESULTING IN A MARGINAL WIND ADVISORY EVENT. WITH SUSTAINED WINDS VERY NEAR 30 MPH AND GUSTS TO 40 MPH OVER A FAIRLY LARGE AREA...DECIDED TO ISSUE A WIND ADVISORY FOR THE SOUTHWEST AND NORTH CENTRAL ZONES. WINDS WILL INCREASE FIRST ACROSS THE SOUTHWEST LATE THURSDAY MORNING...THEN TRANSLATE INTO NORTH CENTRAL BEGINNING IN THE EARLY AFTERNOON. WINDS WILL THEN DIMINISH FROM SOUTH TO NORTH THURSDAY EVENING. AS FAR AS SHOWERS AND THUNDERSTORMS...THERE WILL BE A DIMINISHING EFFECT AS THE SURFACE LOW MOVES FROM SOUTH TO NORTH TODAY. MAIN INSTABILITY WASHES OUT BY 18Z IN THE NORTH AND HAVE ENDED THE THUNDERSTORM THREAT IN THE GRIDDED FORECAST AT THAT TIME. DRY WEATHER COMMENCES CENTRAL AND SOUTH TODAY INTO EARLY TONIGHT. THE NEXT ROUND OF SHOWERS BEGINS IN THE SOUTHWEST EARLY TONIGHT AND GRADUALLY EXPANDS NORTHEAST OVERNIGHT. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 249 AM CDT THU SEP 26 2013 THE MAIN FORECAST ISSUE IN THE LONG TERM PERIOD WILL BE PRECIPITATION CHANCES AND PLACEMENT FRIDAY THROUGH SATURDAY MORNING. THERE IS STILL SOME DISAGREEMENT AMONG THE DETERMINISTIC MODELS WITH PRECIPITATION ACROSS NORTH DAKOTA ON FRIDAY. HOWEVER...THERE IS MUCH BETTER AGREEMENT FRIDAY NIGHT INTO SATURDAY MORNING. WE BEGIN THE LONG TERM PERIOD ON FRIDAY WITH AN UPPER LEVEL TROUGH OVER THE NORTHERN AND CENTRAL ROCKIES. SHEARED VORTICITY ALONG THE LEADING EDGE OF THE TROUGH EXTENDS ACROSS EASTERN MONTANA AND WESTERN NORTH DAKOTA. THE ECMWF IS SHOWING A BROAD AREA OF LIGHT TO MODERATE RAIN LIFTING SOUTHWEST TO NORTHEAST ACROSS THE FORECAST AREA...WHILE THE GFS/GEM CONTINUE TO INDICATE TWO SEPARATE AREAS OF PRECIPITATION...ONE OVER THE WESTERN DAKOTAS ASSOCIATED WITH THE UPPER LEVEL TROUGH...AND ANOTHER OVER EASTERN NORTH DAKOTA ASSOCIATED WITH THE SURFACE SYSTEM...AND A DRY SLOT OVER CENTRAL NORTH DAKOTA. DUE TO CONTINUED DIFFERENCES...WILL SETTLE ON A BROAD BRUSH OF CHANCE TO HIGH CHANCE POPS UNTIL THERE IS BETTER MODEL AGREEMENT. EITHER WAY IT WILL BE QUITE COOL AND CLOUDY WITH SCATTERED LIGHT RAIN AND HIGHS MAINLY IN THE 50S. THERE IS BETTER MODEL AGREEMENT AS THE KICKER SHORTWAVE ROUNDS THE BASE OF THE UPPER TROUGH AND LIFTS INTO THE CENTRAL PLAINS FRIDAY NIGHT. STRONG 2D FRONTOGENESIS SETS UP OVER THE EASTERN DAKOTAS FRIDAY NIGHT AS THE SURFACE LOW TRACKS FROM THE CENTRAL PLAINS INTO NORTHERN MINNESOTA BY SATURDAY MORNING. THIS RESULTS IN AN ENHANCED BAND OF DEFORMATION RAIN OVER FAR SOUTH CENTRAL NORTH DAKOTA THROUGH THE JAMES RIVER VALLEY AND INTO EASTERN NORTH DAKOTA. THE RAIN WILL EXIT THE JAMES RIVER VALLEY SATURDAY MORNING WITH CLEARING SKIES OVER WESTERN NORTH DAKOTA. WE WILL NEED TO MONITOR FOR POSSIBLE FROST HIGHLIGHTS ACROSS THE WEST ON SATURDAY MORNING WITH LOWS POSSIBLY FALLING INTO THE MID TO UPPER 30S IF SKIES CLEAR AND WINDS SUBSIDE. UPPER LEVEL RIDGING BUILDS OVER THE AREA THROUGH THE REMAINDER OF THE WEEKEND WITH TEMPERATURES WARMING INTO THE 70S BY SUNDAY AND MONDAY. A QUASI-ZONAL FLOW THEN TAKES SHAPE THROUGH MID WEEK WITH THE STORM TRACK SITUATED NORTH OF THE BORDER. THUS MAINLY DRY CONDITIONS ARE EXPECTED EARLY NEXT WEEK. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 101 PM CDT THU SEP 26 2013 MVFR CIGS WILL GRADUALLY IMPROVE TO VFR FROM SOUTH TO NORTH THIS AFTERNOON. VFR CONDITIONS ARE EXPECTED TO CONTINUE OVER WESTERN AND CENTRAL NORTH DAKOTA TONIGHT. MVFR CONDITIONS WILL SPREAD FROM SOUTHWEST TO NORTHEAST FRIDAY MORNING AS SHOWERS DEVELOP. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...TM SHORT TERM...KS LONG TERM...TWH AVIATION...TM
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1235 PM CDT THU SEP 26 2013 .UPDATE... ISSUED AT 1235 PM CDT THU SEP 26 2013 EXPANDED THE MOSTLY CLOUDY SKY INTO THE VALLEY THROUGH MUCH OF THE AFTERNOON HOURS. 15Z RAP INDICATES CLEARING POSSIBLE THIS EVENING...SO KEPT THAT IDEA. CURRENT TEMPERATURES APPEAR TO BE ON TRACK WITH THE FORECASTED HIGHS. WINDS AND PRECIP ARE BEHAVING AS EXPECTED. && .SHORT TERM...(TODAY THROUGH FRIDAY) ISSUED AT 330 AM CDT THU SEP 26 2013 THE MAIN CHALLENGE WILL BE PRECIP CHANCES FRIDAY INTO SATURDAY. MODELS HAVE COME INTO BETTER AGREEMENT WITH NEXT SYSTEM...AND THE POTENTIAL FOR A FAIRLY LARGE AREA TO RECEIVE AN INCH OR MORE OF RAIN. THE GFS/ECMWF APPEARS TO BE A GOOD COMPROMISE WITH MINIMAL DIFFERENCES WITH THE ECMWF STILL A BIT SLOWER AND SLIGHTLY FURTHER WEST. FOR TODAY...IT WILL BE WINDY WITH ABOUT 30KT TO MIX FROM THE SOUTH...SHIFTING SW BY LATE AFTERNOON. THERE COULD BE A FEW HOURS THAT ARE BORDERLINE WIND ADVISORY IN THE VALLEY...BUT FEEL WE SHOULD REMAIN BELOW THE 30 MPH SUSTAINED THRESHOLD...BUT SOMETHING THE DAY CREW WILL MONITOR. OTHERWISE...IT WILL BE A VERY WARM DAY WITH SOME AREAS REACHING 80 IN THE SOUTH IN THE WARM SECTOR. THERE COULD ALSO BE A FEW SHOWERS/STORMS THIS MORNING IN THE DEVILS LAKE BASIN INTO THE NORTHERN VALLEY NEAR MID LEVEL WARM ADVECTION AND SOME WEAK INSTABILITY. FOR TONIGHT...EXPECT A DRY START WITH THE CHANCES FOR SHOWERS AND A FEW STORMS INCREASING AFTER 06Z IN THE SOUTH AND EAST. THERE WILL BE INCREASING DEEP LAYERED MOISTURE AND SLIGHTLY NEGATIVE SHOWALTERS ALONG A SFC BOUNDARY...WITH A FEW STRONG STORMS IN THE SOUTH NOT OUT OF THE QUESTION. FOR FRIDAY...EXPECT PLENTY OF CLOUDS WITH INCREASING LIFT AS A SHORTWAVE APPROACHES IN SW FLOW ALOFT. THERE SHOULD BE SHOWERS AND STORMS IN THE SOUTH WITH JUST SHOWERS IN THE NORTH. TEMPS WILL BE MUCH COOLER THAN RECENT DAYS WITH CLOUDS AND PRECIP AROUND. .LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 330 AM CDT THU SEP 26 2013 FOR FRIDAY NIGHT INTO SATURDAY...EXPECT A STRONG SHORTWAVE TO MOVE OVER THE SFC BOUNDARY WITH PWATS AROUND 1.5 INCHES IN THE SOUTH. EXPECT A FAIRLY WIDESPREAD DEFORMATION RAIN BAND TO THE NORTH OF THE SFC FRONT...WITH SOME SHOWERS AND STORMS MAINLY IN THE FAR EASTERN AREAS. RAINFALL COULD BE HEAVY AT TIMES LATER FRIDAY NIGHT INTO SAT MORNING AND STRONG MID LEVEL OMEGA...AND A COUPLED UPPER LEVEL JET ENHANCE DIVERGENCE ALOFT OVER MUCH OF THE REGION. EXPECT AREAS IN THE DEFORMATION RAIN BAND TO GET 1 TO 1.25 INCHES OF RAINFALL WITH LOCALLY HIGHER AMOUNTS POSSIBLE. ON SATURDAY...LIGHT RAIN SHOULD LINGER ALL DAY IN THE FAR EAST WITH A SLOW CLEARING TREND ALONG AND WEST OF THE VALLEY BY AFTERNOON. FOR SUNDAY TO WEDNESDAY NIGHT...NO PCPN IN THE FORECAST FOR THIS PERIOD AS ZONAL FLOW KEEPS MOISTURE SOUTH OF THE AREA. WEAK SHORT WAVES EMBEDDED IN THE MEAN WESTERLY FLOW WILL TRACK NORTH OF THE AREA KEEPING THE BEST PCPN CHANCES IN CANADA MONDAY AND TUESDAY. TEMPS TO BE AT OR ABOVE NORMAL FOR THE FIRST HALF OF THE WEEK WITH 70S SUN TO TUE AND 60S EXPECTED ON WED...STILL NO WIDESPREAD FROST OR KILLING FREEZE ANTICIPATED. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1235 PM CDT THU SEP 26 2013 AVIATION FORECAST CHALLENGE WILL BE CIG HEIGHTS BEHIND APPROACHING COLD FRONT. ARE SEEING MVFR JUST AHEAD OF WIND SHIFT BOUNDARY...WHICH SHOULD REACH DVL IN THE NEXT COUPLE OF HOURS. MOST OF CENTRAL AND WESTERN ND ARE REPORTING MVFR CIGS BEHIND THE FRONT...SO WILL LOWER CIGS FOR GFK/DVL FOR LATE EVENING AND OVERNIGHT. NOT AS CONFIDENT FAR WILL GO MVFR BECAUSE BEST LOW LEVEL MOISTURE IS FURTHER NORTH. WINDS WILL SHIFT FROM S TO NW AT ALL SITES EXCEPT BJI BY FRI MORNING. EXPECT MVFR CIGS TO GRADUALLY FILL IN REMAINDER OF THE AREA ON FRIDAY. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ UPDATE...TG SHORT TERM...DK LONG TERM...JK/DK AVIATION...SPEICHER
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
545 PM CDT THU SEP 26 2013 UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE .SHORT TERM...TONIGHT AND FRIDAY ISSUED AT 231 PM CDT THU SEP 26 2013 LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW HIGH PRESSURE STRETCHING FROM NORTHERN QUEBEC TO THE WESTERN GREAT LAKES EARLY THIS AFTERNOON. MEANWHILE...A LOW PRESSURE AND COLD FRONT ARE SLOWLY MOVING EAST OVER THE NORTHERN PLAINS. MOST OF THE FOG BURNED OFF BY 16Z...LEAVING SUNNY SKIES ACROSS THE REGION. WITH PLENTY OF CLEAR SKIES ALL THE WAY TO THE COLD FRONT...FOG AGAIN IS THE MAIN FORECAST CONCERN TONIGHT...FOLLOWED BY TEMPERATURES ON FRIDAY. TONIGHT...THE MID-LEVEL RIDGE WILL REMAIN IN CLOSE PROXIMITY TO THE REGION...WHILE SURFACE HIGH PRESSURE DRIFTS A LITTLE EASTWARD. AS A COLD FRONT MOVES TOWARDS THE NORTHERN MISSISSIPPI VALLEY...THE LOW LEVEL PRESSURE GRADIENT WILL BE TIGHTENING WHICH WILL RESULT IN 1000-850MB WINDS OF 15-20 KTS. THOUGH THE BL WILL BE MORE MIXY...THE NAM IS STILL DEPICTING CALM WINDS OVER NORTHEAST WISCONSIN LATE TONIGHT. SO UNFORTUNATELY...FOG WILL REMAIN A CONCERN...JUST NOT AS MUCH AS YESTERDAY. WILL STILL SHOW AREAS OF FOG NORTH OF THE FOX VALLEY AND WOULD NOT BE SURPRISED TO SEE SOME PATCHY DENSE FOG SHOW UP. WILL LEAVE A PATCHY FOG MENTION OVER CENTRAL AND EAST-CENTRAL WISCONSIN. LOWS WILL CONTINUE THEIR WARMING TREND...AND WILL GO WITH MID 40S NORTH TO LOW 50S SOUTH AND WEST. FRIDAY...ONCE ANY FOG BURNS OFF EARLY...WILL SEE ANOTHER SUNNY DAY AS THE FRONT WILL REMAIN OVER THE NORTHERN MISSISSIPPI VALLEY. WARMER AIR WILL INVADE THE REGION...WHICH WILL PUSH HIGHS INTO THE MID 70S TO LOW 80S. SOUTHEAST WINDS WILL ALSO BECOME GUSTY. .LONG TERM...FRIDAY NIGHT THROUGH THURSDAY ISSUED AT 231 PM CDT THU SEP 26 2013 MAIN ISSUE THIS PERIOD...PCPN SAT. TIMING DIFFERENCES CONTINUE TO BE SEEN WITH COLD FRONT/UPPER SHORT WAVE EXPECTED TO CROSS STATE SAT/SAT NIGHT. LITTLE CHANGE IN PREVIOUS THOUGHTS WITH PCPN TIED TO FRONT...GOOD MOISTURE CONVERGENCE AND SOME UPPER DIVERGENCE WITH JET LIFTING NORTH INTO CANADA. MAIN DYNAMICS WITH SHORT WAVE LIFT NORTH AND WEST OF CWA...HAVE CARRIED HIGHEST POPS SAT AFTN OVER FAR NORTH. INSTABILITY WEAK AND DIMINISHES FURTHER AS MOVES INTO WI. HAVE LIMITED THUNDER TO JUST SAT AFTERNOON. MODELS CONTINUE TO SHOW THE RAIN MOVING THROUGH THE AREA RATHER QUICKLY. HAVE CONFINED POPS TO BETWEEN NOON AND MIDNIGHT SAT. A MORE ZONAL UPPER LEVEL FLOW PATTERN EXPECTED THROUGH MID WEEK. ISSUES WITH HOW MODELS HANDLING PACIFIC ENERGY LATER IN THE PERIOD. PCPN CHANCES THROUGH WED LOW...THUS HAVE REMOVED SMALL POPS KEEPING CHANCE ON THU AS FLOW BECOMES A BIT MORE AMPLIFIED. MUCH ABOVE NORMAL TEMPERATURES AHEAD OF THE APPROACHING COLD FRONT WITH GUSTY SOUTH WINDS ON SAT...WILL GIVE WAY TO COOLER...BUT STILL ABOVE NORMAL DAYTIME HIGHS. && .AVIATION...FOR 00Z TAF ISSUANCE ISSUED AT 544 PM CDT THU SEP 26 2013 SLIGHTLY DIFFERENT WX PATTERN TNGT...BUT STILL EXPECTING ISSUES WITH FOG. SFC HIGH HAS EDGED A BIT FARTHER E...WITH FRONTAL SYSTEM NOW BEGINNING TO SLOWLY ADVANCE E FM THE NRN PLAINS. THOSE CHGS WL RESULT IN A LITTLE STRONGER SFC PRESSURE GRADIENT ACRS THE AREA TNGT...ESP ACRS THE WRN 1/2 OF THE FCST AREA. WINDS ATOP THE BOUNDARY LAYER WL ALSO BE A BIT STRONGER. THOSE FACTORS WOULD SEEM SUFFICIENT TO PREVENT SIG FOG FORMATION. HOWEVER...BASED ON WHAT/S HAPPENED THE PAST FEW NIGHTS...DON/T THINK THEY WL BE ABLE TO HOLD THE FOG OFF...ESP IN THE E. WL HIT FOG MUCH HARDER IN THE ERN TAF SITES. WL TREND SOMEWHAT MORE PESSIMISTIC ACRS THE W ALSO...THOUGH CONDITIONS THERE SHOULD NOT BE AS BAD AS THE PAST FEW MORNINGS. && .MARINE... ISSUED AT 231 PM CDT THU SEP 26 2013 AN EXTENDED PERIOD OF SOUTHERLY WINDS FRIDAY NIGHT AND SATURDAY WILL BUILD WAVES OVER LAKE MICHIGAN WITH SMALL CRAFT CONDITIONS EXPECTED. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......TE AVIATION.......SKOWRONSKI MARINE.........TE
FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE

.SHORT TERM...TONIGHT AND FRIDAY ISSUED AT 231 PM CDT THU SEP 26 2013 LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW HIGH PRESSURE STRETCHING FROM NORTHERN QUEBEC TO THE WESTERN GREAT LAKES EARLY THIS AFTERNOON. MEANWHILE...A LOW PRESSURE AND COLD FRONT ARE SLOWLY MOVING EAST OVER THE NORTHERN PLAINS. MOST OF THE FOG BURNED OFF BY 16Z...LEAVING SUNNY SKIES ACROSS THE REGION. WITH PLENTY OF CLEAR SKIES ALL THE WAY TO THE COLD FRONT...FOG AGAIN IS THE MAIN FORECAST CONCERN TONIGHT...FOLLOWED BY TEMPERATURES ON FRIDAY. TONIGHT...THE MID-LEVEL RIDGE WILL REMAIN IN CLOSE PROXIMITY TO THE REGION...WHILE SURFACE HIGH PRESSURE DRIFTS A LITTLE EASTWARD. AS A COLD FRONT MOVES TOWARDS THE NORTHERN MISSISSIPPI VALLEY...THE LOW LEVEL PRESSURE GRADIENT WILL BE TIGHTENING WHICH WILL RESULT IN 1000-850MB WINDS OF 15-20 KTS. THOUGH THE BL WILL BE MORE MIXY...THE NAM IS STILL DEPICTING CALM WINDS OVER NORTHEAST WISCONSIN LATE TONIGHT. SO UNFORTUNATELY...FOG WILL REMAIN A CONCERN...JUST NOT AS MUCH AS YESTERDAY. WILL STILL SHOW AREAS OF FOG NORTH OF THE FOX VALLEY AND WOULD NOT BE SURPRISED TO SEE SOME PATCHY DENSE FOG SHOW UP. WILL LEAVE A PATCHY FOG MENTION OVER CENTRAL AND EAST-CENTRAL WISCONSIN. LOWS WILL CONTINUE THEIR WARMING TREND...AND WILL GO WITH MID 40S NORTH TO LOW 50S SOUTH AND WEST. FRIDAY...ONCE ANY FOG BURNS OFF EARLY...WILL SEE ANOTHER SUNNY DAY AS THE FRONT WILL REMAIN OVER THE NORTHERN MISSISSIPPI VALLEY. WARMER AIR WILL INVADE THE REGION...WHICH WILL PUSH HIGHS INTO THE MID 70S TO LOW 80S. SOUTHEAST WINDS WILL ALSO BECOME GUSTY. .LONG TERM...FRIDAY NIGHT THROUGH THURSDAY ISSUED AT 231 PM CDT THU SEP 26 2013 MAIN ISSUE THIS PERIOD...PCPN SAT. TIMING DIFFERENCES CONTINUE TO BE SEEN WITH COLD FRONT/UPPER SHORT WAVE EXPECTED TO CROSS STATE SAT/SAT NIGHT. LITTLE CHANGE IN PREVIOUS THOUGHTS WITH PCPN TIED TO FRONT...GOOD MOISTURE CONVERGENCE AND SOME UPPER DIVERGENCE WITH JET LIFTING NORTH INTO CANADA. MAIN DYNAMICS WITH SHORT WAVE LIFT NORTH AND WEST OF CWA...HAVE CARRIED HIGHEST POPS SAT AFTN OVER FAR NORTH. INSTABILITY WEAK AND DIMINISHES FURTHER AS MOVES INTO WI. HAVE LIMITED THUNDER TO JUST SAT AFTERNOON. MODELS CONTINUE TO SHOW THE RAIN MOVING THROUGH THE AREA RATHER QUICKLY. HAVE CONFINED POPS TO BETWEEN NOON AND MIDNIGHT SAT. A MORE ZONAL UPPER LEVEL FLOW PATTERN EXPECTED THROUGH MID WEEK. ISSUES WITH HOW MODELS HANDLING PACIFIC ENERGY LATER IN THE PERIOD. PCPN CHANCES THROUGH WED LOW...THUS HAVE REMOVED SMALL POPS KEEPING CHANCE ON THU AS FLOW BECOMES A BIT MORE AMPLIFIED. MUCH ABOVE NORMAL TEMPERATURES AHEAD OF THE APPROACHING COLD FRONT WITH GUSTY SOUTH WINDS ON SAT...WILL GIVE WAY TO COOLER...BUT STILL ABOVE NORMAL DAYTIME HIGHS. && .AVIATION...FOR 18Z TAF ISSUANCE ISSUED AT 1239 PM CDT THU SEP 26 2013 HIGH PRESSURE WILL DEPART TO THE EAST AS A COLD FRONT MOVES ACROSS THE NORTHERN PLAINS OVER THE PERIOD. BETWEEN THE TWO SYSTEMS...WINDS WILL BE GRADUALLY INCREASING FROM THE SOUTH-SOUTHEAST. THE WINDS WILL ALLEVIATE FOG CONCERNS TONIGHT...BUT STILL DROPPED VSBYS AT THE TAF SITES INTO THE IFR/MVFR RANGE LATE. PATCHY DENSE FOG MAY STILL BE POSSIBLE NORTH OF THE FOX VALLEY. ONCE ANY FOG LIFTS FRIDAY MORNING...SOUTH WINDS WILL TURN GUSTY BUT OTHERWISE...GOOD FLYING WEATHER WILL BE PRESENT. && .MARINE... ISSUED AT 231 PM CDT THU SEP 26 2013 AN EXTENDED PERIOD OF SOUTHERLY WINDS FRIDAY NIGHT AND SATURDAY WILL BUILD WAVES OVER LAKE MICHIGAN WITH SMALL CRAFT CONDITIONS EXPECTED. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......TE AVIATION.......MPC MARINE.........TE
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
103 PM CDT THU SEP 26 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 321 AM CDT THU SEP 26 2013 AT 3 AM...A 1020 MB HIGH WAS CENTERED NORTH OF LAKE HURON. EASTERLY WINDS ON THE SOUTHERN PERIPHERY OF THIS HIGH CONTINUES TO BRING LOWER AND MID 40 DEW POINTS INTO CENTRAL AND NORTH-CENTRAL WISCONSIN. THE COMBINATION OF THESE DEW POINTS ALONG WITH CLEAR SKIES AND LIGHT WINDS HAS ALLOWED TEMPERATURES THESE AREAS TO COOL INTO THE LOWER AND MID 40S. WITH THESE TEMPERATURES COOLER THAN THE WATER TEMPERATURES...STEAM FOG HAS DEVELOPED IN THIS AREA. THERE ARE EVEN A FEW REPORTS OF DENSE FOG AT VOLK FIELD AND WAUTOMA. WITH BUFKIT RAP SOUNDINGS CONTINUING TO SHOW THAT THE WINDS BELOW 900 MB WILL BE INCREASING TO AROUND 10 KNOTS BY SUNRISE...NOT EXPECTING THIS FOG TO BECOME AS WIDESPREAD AS WEDNESDAY MORNING. HOWEVER WITH THIS SAID...WE ARE STILL CONSIDERING A DENSE FOG ADVISORY IN ADAMS AND JUNEAU COUNTIES IN CENTRAL WISCONSIN. SHERIFF DEPARTMENTS IN BOTH OF THESE COUNTIES ARE REPORTING PATCHY DENSE FOG. THE RAP WOULD SUGGEST THAT THE LOW LEVEL MOISTURE WILL INCREASE THROUGH THE REMAINDER OF THIS MORNING. MEANWHILE NAM/WRF SHOWS THAT THIS LOW LEVEL MOISTURE MIXES OUT BY 26.14Z. FOR TODAY...HIGH PRESSURE WILL PROVIDE ANOTHER SUNNY DAY ACROSS THE UPPER MISSISSIPPI RIVER VALLEY. AS DIURNAL HEATING MIXES OUT THE NOCTURNAL INVERSION THIS MORNING...EXPECT WIND GUSTS TO CLIMB INTO THE 15 TO 30 MPH BETWEEN 10 AM AND NOON...AND THEN CONTINUE THROUGH THE AFTERNOON. LIKE YESTERDAY...IT LOOKS LIKE THE AREA WILL MIX TO AROUND 875 MB. THIS WILL YIELD TEMPERATURES IN THE LOWER TO MID 70S NORTH OF INTERSTATE 94...AND FROM THE MID 70S TO AROUND 80 ACROSS THE REMAINDER OF THE AREA. FOR TONIGHT...THE CENTER OF SURFACE HIGH WILL DRIFT EAST INTO QUEBEC. THIS WILL ALLOW THE COLD FRONT...CURRENTLY LOCATED OVER THE CENTRAL DAKOTAS...TO MOVE EAST INTO WESTERN AND NORTHERN MINNESOTA. AS THIS OCCURS...SOME MOISTURE BETWEEN 600 AND 700 MB WILL MOVE EAST INTO THE FORECAST AFTER AFTER 27.08Z. THE NOCTURNAL INVERSION WILL QUICKLY THIS EVENING WITH THE LOSS OF DIURNAL HEATING. AS THIS OCCURS...THE WIND GUSTS WILL DIMINISH. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 321 AM CDT THU SEP 26 2013 FROM FRIDAY AFTERNOON INTO FRIDAY NIGHT...THE 26.00Z MODELS ARE IN VERY GOOD AGREEMENT THAT THE COLD FRONT WILL MOVE EAST INTO WESTERN MINNESOTA DURING THE AFTERNOON AND EVENING...AND THEN IT STALLS ITS EASTWARD PROGRESS ON FRIDAY NIGHT AS A SURFACE LOW MOVES NORTH ALONG IT. WITH SOUNDINGS CONTINUING TO SHOW CAPPING BETWEEN 800 AND 650 MBS AND DRY AIR AHEAD OF THIS FRONT...NOT EXPECTING ANY PRECIPITATION TO OCCUR AHEAD OF IT....THUS KEPT THE FORECAST DRY. FROM SATURDAY INTO SATURDAY EVENING...THE MODELS CONTINUE TO SHOW THAT THE SURFACE COLD FRONT AND SHORT WAVE TROUGH WILL MOVE QUICKLY EAST ACROSS THE AREA. LIKE THE PAST DAYS...THE 0-6 KM SHEAR REMAINS ABOVE 40 KNOTS ALONG AND IN THE WAKE OF THE FRONT. HOWEVER THE ML CAPES REMAIN GENERALLY LESS THAN 100 J/KG...SO STILL NOT CONCERNED THAT THE AREA WILL EXPERIENCE ANY SEVERE WEATHER. JUST TOO LITTLE INSTABILITY FOR THE AMOUNT SHEAR. OVERALL...ACTUALLY THINK THAT OUR BEST CHANCE OF THUNDER WILL ACTUALLY COME FROM MORE SLANTWISE THAN UPRIGHT CONVECTION. DUE TO THE CONSISTENCY OF THE TIMING WITH THE FRONTOGENESIS...RAISED THE PRECIPITATION CHANCES INTO THE 75 TO 84 PERCENT RANGE. THINKING WITH THE SPEED OF THE SHORT WAVE TROUGH AND FRONT THAT THE PRECIPITATION WILL LIKELY ONLY LAST 2 TO 4 HOURS IN ANY LOCATION. FROM TUESDAY INTO WEDNESDAY...THE MODELS ARE NOW SHOWING THAT THE SHORT WAVE WILL PASS WELL NORTH OF THE AREA. DUE TO THIS...THE PRECIPITATION CHANCES WERE REMOVED FROM THE FORECAST. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 103 PM CDT THU SEP 26 2013 VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD. HIGH PRESSURE WILL BE IN PLACE OVER THE EASTERN GREAT LAKES AS TROUGH OF LOW PRESSURE DEEPENS OVER THE NORTHERN AND CENTRAL PLAINS...PLACING THE UPPER MISSISSIPPI RIVE VALLEY IN A TIGHT PRESSURE GRADIENT. PLAN ON BREEZY SOUTH/SOUTHEAST WINDS AT 15 TO 17 KTS. KLSE WILL DECOUPLE LATE THIS EVENING...LEADING TO LOW LEVEL WIND SHEAR. WINDS INCREASE TO AROUND 40 KTS AT 1KFT. HAVE INCLUDED LLWS IN THE TAF AT KLSE FROM 05Z THROUGH 14Z. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...BOYNE LONG TERM...BOYNE AVIATION...WETENKAMP
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1135 AM CDT THU SEP 26 2013 .UPDATE...CLEAR SKIES ARE EXPECTED FOR MOST OF THE AREA TODAY. HOWEVER...SOME CU HAS DEVELOPED IN THE EAST...ESPECIALLY NEAR SHEBOYGAN...WHERE DEW POINTS ARE HIGHER AND SOUTHEAST WINDS OFF THE LAKE ARE PROVIDING CONVERGENCE. THE CLOUDS ARE EXPECTED TO DISSIPATE...AS MIXING OCCURS AND RAP FORECAST SOUNDINGS SHOW ABUNDANT DRY AIR AND SUBSIDENCE AROUND 850 MB BY EARLY AFTERNOON. TEMPERATURES MAY GET A FEW DEGREES WARMER THIS AFTERNOON THAN PLANNED. 925 MB TEMPS RANGE FROM 17 TO 20 C...WHICH WOULD GIVE US HIGHS IN THE MID TO UPPER 70S. WHILE TEMPERATURES ALONG THE LAKE ARE RISING QUICKLY...THEY ARE EXPECTED TO MODERATE THIS AFTERNOON THANKS TO THE ONSHORE WIND. HIGH TEMPERATURES ARE NOW EXPECTED TO RANGE FROM THE LOWER 70S IN THE EAST...TO THE UPPER 70S IN THE WEST. MEB && .AVIATION/18Z TAFS/...HIGH PRESSURE WILL REMAIN WELL EAST OF THE REGION THROUGH FRIDAY. LIGHT SOUTHEAST WINDS ARE EXPECTED UNTIL SUNSET...WITH A FEW DIURNAL CUMULUS CLOUDS AT THE EASTERN SITES. LIGHT SOUTHEAST WINDS SHOULD LINGER THROUGH TONIGHT AND EARLY FRIDAY MORNING...THOUGH COULD SEE LIGHT/VARIABLE OR CALM WINDS AT TIMES. PATCHY FOG WITH MVFR VISIBILITIES ARE EXPECTED AT SITES EXCEPT MILWAUKEE BETWEEN 08Z AND 13Z FRIDAY. LIGHT TO MODERATE SOUTHEAST WINDS ARE EXPECTED FOR THE REST OF FRIDAY...WITH GUSTS TO 17 KNOTS AT TIMES. SCATTERED DIURNAL CUMULUS ARE POSSIBLE DURING THE LATE MORNING AND EARLY AFTERNOON...ESPECIALLY AT THE EASTERN SITES. WOOD && .MARINE...WINDS AND WAVES MAY REACH SMALL CRAFT ADVISORY LEVELS MAINLY ON SATURDAY ACROSS THE NEARSHORE WATERS OF LAKE MICHIGAN. A TIGHT PRESSURE GRADIENT AHEAD OF A COLD FRONT SHOULD BRING GUSTY SOUTH/SOUTHEAST WINDS UP TO 25 KNOTS DURING THIS TIME. THESE WINDS SHOULD GENERATE HIGH WAVES OF 3 TO 6 FEET. WOOD && .PREV DISCUSSION... /ISSUED 318 AM CDT THU SEP 26 2013/ TODAY AND TONIGHT...FORECAST CONFIDENCE...MEDIUM TO HIGH 500/250 MB RIDGE WILL BUILDS ACROSS EASTERN WISCONSIN AND THEN OVER THE WESTERN GREAT LAKES LATE TONIGHT WITH DEVELOPING SOUTHWEST FLOW OVER THE UPPER MISSISSIPPI VALLEY. THE 850/700/500 MB LAYERS REMAIN DRY ALTHOUGH 850 MB RH INCREASES TOWARD THE MISSISSIPPI VALLEY BY TONIGHT AS A STRONG SOUTH LOW LEVEL EXTENDS FROM WESTERN KANSAS TO MINNESOTA. HOWEVER THE RIDGE WILL REMAIN IN PLACE OVER THE GREAT LAKES. ONLY A SLIGHT INCREASE IN 850/700 MB TEMPERATURES LATER TODAY. THE SURFACE RIDGE WILL REMAIN OVER THE GREAT LAKES BUT THE LIGHT EAST WINDS WILL BECOME MORE SOUTHEAST TONIGHT AND INCREASE SLIGHTLY OVER SOUTH CENTRAL WISCONSIN. MAIN ISSUE WILL BE THE VERY SHORT TERM WITH GOOD LONG WAVE RADIATIONAL CONDITIONS DURING THE EARLY MORNING HOURS. VERY LIGHT EAST FLOW SHOULD RESULT IN AREAS OF DENSE FOG. HOWEVER BOUNDARY LAYER WINDS A BIT STRONGER THAN LAST NIGHT. STILL...FAIRLY SIMILAR SETUP TO LAST NIGHT WHICH HAD DENSE FOG VISIBILITIES BOUNCING UP AND DOWN IN MANY LOCATIONS. RADIATIONAL CONDITIONS NOT QUITE AS GOOD LATE TONIGHT BUT AREAS OF FOG STILL EXPECTED ESPECIALLY EAST. FRIDAY - CONFIDENCE...HIGH WARM DAY WITH SOUTHERLY FLOW AHEAD OF THE APPROACHING PLAINS COLD FRONT. MODELS AGREE ON 925 TEMPS 18-20C FROM EAST TO WEST ACROSS THE CWA. DYNAMICS AND FRONTAL FORCING REMAIN ACROSS MN AND IA. SATURDAY AND SATURDAY NIGHT - CONFIDENCE...MEDIUM LOW LEVEL THERMAL RIDGE ORIENTED ACROSS THE STATE AT 18Z. FRONT THEN SWEEPS THROUGH DURING THE AFTERNOON EXITING THE SOUTHEAST AROUND 00Z. CWASP INTO THE 60S BUT BUFKIT IS REALLY SHOWING LITTLE IN THE WAY OF INSTABILITY. WAS TEMPTED TO REMOVE THUNDER ALL TOGETHER BUT LEFT THE TOKEN ISOLATED IN THE GRIDS. FIRST AND MORE SIGNIFICANT SHORTWAVE ALIGNED WITH LOW LEVEL FORCING FEATURES WHISKS EAST THOUGH LAGS SPEED OF SURFACE/850 FORCING. 12Z AND 00Z ECMWF NOT ADDING GREAT CONFIDENCE TO GOING DRY AFTER 6Z SATURDAY NIGHT SO LINGERED A HIGHER CHANCES IN THE EAST AND TO MESH BETTER WITH SURROUNDING OFFICES. OTHER MODELS MORE PROGRESSIVE AND IMPLY THINGS DRY OUT AFTER 6Z. SO ADDITIONAL REFINEMENT OF THE TIMING LIKELY AS MODELS COME INTO BETTER AGREEMENT. SUNDAY THROUGH WEDNESDAY - CONFIDENCE...MEDIUM OVERALL A WARM PERIOD. QUICK HITTING THERMAL TROUGH IN THE WAKE OF THE FRONTAL BOUNDARY. HIGH SHIFTS EAST MONDAY AND RETURN FLOW SETS UP WITH MODIFYING 925 TEMPS. GFS MORE AGGRESSIVE WITH WEDNESDAY PRECIP THOUGH MAIN SUPPORT FOR PRECIP LOOKS TO BE WELL NORTH WITH THE STRONGER WESTERLIES. SO PER COLLAB WITH SURROUNDING OFFICES...WILL KEEP FORECAST DRY GIVEN THE NOD TO THE DRY LOOK OF THE ECMWF. AVIATION/12Z TAFS/...MVFR/IFR FOG EARLY THIS MORNING WITH SOME LIFR FOG ESPECIALLY IN LOW AREAS AND RIVER VALLEYS. FOG WILL DISSIPATE DURING THE MID TO LATE MORNING. LESS MOISTURE MOISTURE BELOW THE INVERSION AROUND 3 TO 4 THSD FT TO GENERATE FEW FAIR WEATHER CUMULUS WITH VFR CONDITIONS BY AFTERNOON. SURFACE RIDGE WILL REMAIN OVER THE GREAT LAKES. VFR CONDITIONS DURING THE EVENING. THEN PATCHY IFR VSBYS AGAIN LATE TONIGHT WITH FOG...ESPECIALLY EAST IN LOW AREAS AND RIVER VALLEYS. MARINE...WINDS AND WAVES MAY REACH SMALL CRAFT ADVISORY LEVELS MAINLY ON SATURDAY ACROSS THE NEARSHORE WATERS OF LAKE MICHIGAN. A TIGHT PRESSURE GRADIENT AHEAD OF A COLD FRONT SHOULD BRING GUSTY SOUTH/SOUTHEAST WINDS UP TO 25 KNOTS DURING THIS TIME. THESE WINDS SHOULD GENERATE HIGH WAVES OF 3 TO 6 FEET. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...NONE. && $$ UPDATE...MEB/WOOD TODAY/TONIGHT AND AVIATION/MARINE...HENTZ FRIDAY THROUGH WEDNESDAY...COLLAR