Forecast Discussions mentioning "ACARS", "MDCRS", "AIRCRAFT", "TAMDAR", or "AMDAR" received at FSL on 09/18/08

AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
617 AM CDT TUE SEP 16 2008 .DISCUSSION... 237 AM CDT AS NOAH`S ARK SAILS DOWN THE DES PLAINES RIVER INTO THE HORIZON DOWN THE ILLINOIS RIVER...WE ARE LEFT WITH QUITE THE QUIET WEATHER PATTERN WITH THE BIGGEST EXCITEMENT COMING ON WEDNESDAY IN THE FORM OF A WEAK COLD FRONT. MAIN QUESTION IN THE SHORT TERM IS WITH THE FOG DEVELOPMENT THIS MORNING AS SHALLOW GROUND FOG HAS DROPPED VIS TO A QUARTER MILE AT A FEW SITES ACROSS NORTH CENTRAL ILLINOIS. WINDS HAVE GONE CALM WITH CLEAR SKIES AND A DECENT AMOUNT OF LEFTOVER GROUND MOISTURE FROM THIS WEEKEND`S RAIN THAT THIS FOG IS DEVELOPING AT THE SURFACE AND IS GETTING TRAPPED UNDER A RATHER SHALLOW 1KFT LOW LEVEL INVERSION AS NOTED BY AN ACARS SOUNDING OUT OF RFD. CURRENT THINKING IS THAT CONDITIONS WILL LIKELY CONTINUE TO WORSEN OVER THE NEXT FEW HOURS TO THE POINT THAT A DENSE FOG ADVISORY WILL NEED TO BE ISSUED FOR A FEW COUNTIES ACROSS NORTH CENTRAL ILLINOIS. AFTER THE FOG DISSIPATES EARLY IN THE MORNING...A GLORIOUS DAY IS ON TAP WITH BOUNTIFUL SUNSHINE AND HIGH TEMPERATURES CLIMBING BACK UP INTO THE LOW 70S AS 850MB WINDS TURN OUT OF THE WEST AND ADVECT WARMER AIR INTO THE REGION. ONTO WEDNESDAY WITH THE COLD FRONT. 850MB THERMAL RIDGE WILL START POKING INTO THE REGION WHICH WILL HELP TEMPERATURES CLIMB INTO THE UPPER 70S OUT AHEAD OF THE SINKING COLD FRONT THAT IS EXPECTED TO DROP DOWN THE LAKE IN THE AFTERNOON WEDNESDAY. NOT A WHOLE LOT OF FORCE WITH THIS FRONT AS THE PARENT LOW IS WAY UP BY THE HUDSON BAY AND ANY MOISTURE SOURCE IS NON-EXISTENT AS SFC HIGH PRESSURE SETS UP ACROSS MOST OF THE SOUTHERN US...THUS CLOSING OFF THE GULF. FORECAST SOUNDINGS ARE TRYING TO PUMP OUT 250J/KG OF ELEVATED CAPE OUT AHEAD OF THIS FRONT...BUT THINK THAT THE MISSING MOISTURE AND LIFT COMPONENTS WILL KEEP THAT INSTABILITY FROM BEING USED. CLOUD COVER SHOULD INCREASE A BIT AS THE FRONT DROPS DOWN BUT SKIES SHOULD CLEAR OUT RATHER RAPIDLY AFTER WARDS WITH ANOTHER BROAD RIDGE OF HIGH PRESSURE BUILDING DOWN FROM CANADA. UPPER FLOW GOES FAIRLY ZONAL THRU THE REST OF THE WEEK AS AN UPPER LEVEL RIDGE CURRENTLY OVER THE ROCKIES BUILDS EASTWARD THROUGH THE WEEK. TEMPS WILL GRADUALLY WARM THROUGH THE END OF THE WEEK AFTER THE FRONT COMES THROUGH WED EVENING WITH WINDS EVENTUALLY COMING BACK AROUND TO THE SOUTH-SOUTHWEST TOWARD THE WEEKEND. HALBACH && .AVIATION... 1200 UTC TAFS...SHALLOW GROUND FOG HAS DEVELOPED IN OUTLYING AREAS THIS MORNING...WITH VSBY FLUCTUATING BETWEEN VLIFR AND VFR AT RURAL TAF SITES. THE FOG SHOULD RAPIDLY BURN OFF EARLY THIS MORNING WITH UNRESTRICTED CIGS/VSBY LIKELY BY MID/LATE MORNING AND CONTINUING THROUGH THE THE REMAINDER OF THE TAF CYCLE. SOUTHWEST WINDS WILL DEVELOP LATER THIS MORNING AND CONTINUE BETWEEN 7-10KT THROUGH TONIGHT. IZZI && .MARINE... 102 AM CDT LOW PRESSURE WILL MOVE RAPIDLY EAST FROM LAKE WINNIPEG EARLY THIS MORNING EAST NORTHEAST TO JUST EAST OF HUDSON BAY BY THIS EVENING...WHILE DEEPENING ABOUT 12MB IN THE NEXT 24 HOURS. THE RESULT FOR THE LAKE WILL BE A PERIOD OF FAIRLY STRONG SOUTHWEST WINDS...PARTICULARLY OVER NORTHERN PORTIONS OF THE LAKE THIS AFTERNOON AND EARLY EVENING. SHOULD WRF-NMM AND LOCALLY RUN WRF- ARF FORECAST SOUNDINGS VERIFY...THEN LOW LEVEL LAPSE RATES OVER NORTHERN LAKE MICHIGAN WOULD BE STEEP ENOUGH FOR A TIME THIS AFTERNOON FOR GUSTS TO GALE FORCE. NOT SURE HOW SOLD I AM ON GALES THIS AFTERNOON...WILL COORDINATE WITH SURROUNDING OFFICES AND MAKE A LAST MINUTE DECISION. AFTER THAT...COLD FRONT SWEEPS DOWN THE LAKE WITH WINDS SWINGING AROUND TO NORTH WED BEFORE VEERING MORE EASTERLY THEN SOUTHEAST LATER IN THE WEEK. IZZI && .LOT WATCHES/WARNINGS/ADVISORIES... IL...DENSE FOG ADVISORY...ILZ003-ILZ004-ILZ008-ILZ010-ILZ011-ILZ019- ILZ020-ILZ021-ILZ032-ILZ039 UNTIL 10 AM TUESDAY. IN...NONE. LM...GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ563...4 PM TUESDAY TO 9 PM TUESDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
237 AM CDT TUE SEP 16 2008 .DISCUSSION... 237 AM CDT AS NOAH`S ARK SAILS DOWN THE DES PLAINES RIVER INTO THE HORIZON DOWN THE ILLINOIS RIVER...WE ARE LEFT WITH QUITE THE QUIET WEATHER PATTERN WITH THE BIGGEST EXCITEMENT COMING ON WEDNESDAY IN THE FORM OF A WEAK COLD FRONT. MAIN QUESTION IN THE SHORT TERM IS WITH THE FOG DEVELOPMENT THIS MORNING AS SHALLOW GROUND FOG HAS DROPPED VIS TO A QUARTER MILE AT A FEW SITES ACROSS NORTH CENTRAL ILLINOIS. WINDS HAVE GONE CALM WITH CLEAR SKIES AND A DECENT AMOUNT OF LEFTOVER GROUND MOISTURE FROM THIS WEEKEND`S RAIN THAT THIS FOG IS DEVELOPING AT THE SURFACE AND IS GETTING TRAPPED UNDER A RATHER SHALLOW 1KFT LOW LEVEL INVERSION AS NOTED BY AN ACARS SOUNDING OUT OF RFD. CURRENT THINKING IS THAT CONDITIONS WILL LIKELY CONTINUE TO WORSEN OVER THE NEXT FEW HOURS TO THE POINT THAT A DENSE FOG ADVISORY WILL NEED TO BE ISSUED FOR A FEW COUNTIES ACROSS NORTH CENTRAL ILLINOIS. AFTER THE FOG DISSIPATES EARLY IN THE MORNING...A GLORIOUS DAY IS ON TAP WITH BOUNTIFUL SUNSHINE AND HIGH TEMPERATURES CLIMBING BACK UP INTO THE LOW 70S AS 850MB WINDS TURN OUT OF THE WEST AND ADVECT WARMER AIR INTO THE REGION. ONTO WEDNESDAY WITH THE COLD FRONT. 850MB THERMAL RIDGE WILL START POKING INTO THE REGION WHICH WILL HELP TEMPERATURES CLIMB INTO THE UPPER 70S OUT AHEAD OF THE SINKING COLD FRONT THAT IS EXPECTED TO DROP DOWN THE LAKE IN THE AFTERNOON WEDNESDAY. NOT A WHOLE LOT OF FORCE WITH THIS FRONT AS THE PARENT LOW IS WAY UP BY THE HUDSON BAY AND ANY MOISTURE SOURCE IS NON-EXISTENT AS SFC HIGH PRESSURE SETS UP ACROSS MOST OF THE SOUTHERN US...THUS CLOSING OFF THE GULF. FORECAST SOUNDINGS ARE TRYING TO PUMP OUT 250J/KG OF ELEVATED CAPE OUT AHEAD OF THIS FRONT...BUT THINK THAT THE MISSING MOISTURE AND LIFT COMPONENTS WILL KEEP THAT INSTABILITY FROM BEING USED. CLOUD COVER SHOULD INCREASE A BIT AS THE FRONT DROPS DOWN BUT SKIES SHOULD CLEAR OUT RATHER RAPIDLY AFTER WARDS WITH ANOTHER BROAD RIDGE OF HIGH PRESSURE BUILDING DOWN FROM CANADA. UPPER FLOW GOES FAIRLY ZONAL THRU THE REST OF THE WEEK AS AN UPPER LEVEL RIDGE CURRENTLY OVER THE ROCKIES BUILDS EASTWARD THROUGH THE WEEK. TEMPS WILL GRADUALLY WARM THROUGH THE END OF THE WEEK AFTER THE FRONT COMES THROUGH WED EVENING WITH WINDS EVENTUALLY COMING BACK AROUND TO THE SOUTH-SOUTHWEST TOWARD THE WEEKEND. HALBACH && .AVIATION... 0600 UTC TAFS...PRIMARY...WELL THE ONLY...AVIATION FORECAST CHALLENGE IS FOG POTENTIAL THIS MORNING. VERY MOIST SURFACE CONDITIONS AND STRONG RADIATIONAL COOLING WOULD CERTAINLY FAVOR FOG DEVELOPMENT...HOWEVER WARM SOILS AND SOME SLIGHTLY DRIER AIR DID ADVECT INTO THE REGION WOULD BE THE CONS. HAVE SEEN SEVERAL RURAL SITES BOTTOM OUT AT 1/4SM ALREADY THIS MORNING...AND SEE NO REASON WHY THIS FOG WON`T EXPAND OVERNIGHT AND HAVE TRENDED DOWNWARD AT RFD/DPA WITH A PERIOD OF PREVAILING IFR CONDITIONS AROUND SUNRISE. POTENTIAL FOR VLIFR VSBY WITH OBSCURED CIGS EXIST FOR BOTH SITES...BUT CONFIDENCE IN THAT SCENARIO ISNT HIGH ENOUGH TO FORECAST THAT YET. TOUGH TO SAY HOW LOW CONDITIONS WILL GET AT ORD/MDW GIVEN THE MORE URBANIZED LANDSCAPING THEY ARE SURROUNDED BY. THERE IS CERTAINLY SOME POTENTIAL FOR IFR OR LOWER CONDITIONS FOR A PERIOD OF TIME LATER THIS MORNING THERE AS WELL...BUT TOOK AN OPTIMISTIC APPROACH FOR NOW. WILL CLOSELY MONITOR T/TD AND VSBY TRENDS OVERNIGHT FOR POSSIBLE AMENDMENTS. ANY FOG WILL QUICKLY BURN OFF BY MID MORNING WITH VFR CONDITIONS BY MID/LATE MORNING. IZZI && .MARINE... 102 AM CDT LOW PRESSURE WILL MOVE RAPIDLY EAST FROM LAKE WINNIPEG EARLY THIS MORNING EAST NORTHEAST TO JUST EAST OF HUDSON BAY BY THIS EVENING...WHILE DEEPENING ABOUT 12MB IN THE NEXT 24 HOURS. THE RESULT FOR THE LAKE WILL BE A PERIOD OF FAIRLY STRONG SOUTHWEST WINDS...PARTICULARLY OVER NORTHERN PORTIONS OF THE LAKE THIS AFTERNOON AND EARLY EVENING. SHOULD WRF-NMM AND LOCALLY RUN WRF- ARF FORECAST SOUNDINGS VERIFY...THEN LOW LEVEL LAPSE RATES OVER NORTHERN LAKE MICHIGAN WOULD BE STEEP ENOUGH FOR A TIME THIS AFTERNOON FOR GUSTS TO GALE FORCE. NOT SURE HOW SOLD I AM ON GALES THIS AFTERNOON...WILL COORDINATE WITH SURROUNDING OFFICES AND MAKE A LAST MINUTE DECISION. AFTER THAT...COLD FRONT SWEEPS DOWN THE LAKE WITH WINDS SWINGING AROUND TO NORTH WED BEFORE VEERING MORE EASTERLY THEN SOUTHEAST LATER IN THE WEEK. IZZI && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$
AREA FORECAST DISCUSSION
NWS GAYLORD MI
720 PM EDT WED SEP 17 2008 .SYNOPSIS.../ISSUED AT 342 PM/ HIGH PRESSURE WILL FLOAT ACROSS THE REGION OVER THE NEXT 24 HOURS... FOLLOWED BY A WARM SOUTH/SOUTHWEST RETURN FLOW SETTING UP FOR THE END OF THE WEEK. MAIN BELT OF WESTERLIES WILL BE NORTH OF THE BORDER...BUT A COLD FRONT WILL TRY TO SNEAK IN FOR THE WEEKEND AND PERHAPS BRING OUR NEXT CHANCE FOR RAINFALL. JPB && .SHORT TERM.../ISSUED AT 342 PM/...TONIGHT HIGH PRESSURE SETTLING INTO THE UPPER GREAT LAKES TONIGHT...WITH THE BIGGEST ISSUE REVOLVING AROUND LOW TEMPERATURES AND FROST POTENTIAL. SOME DIURNAL CLOUDS HANGING AROUND THIS AFTERNOON WON`T BE AN ISSUE...BUT WITH COLDER AIR SINKING ACROSS THE REGION (850MB TEMPERATURES FALLING BELOW 4C). THERE WILL PROBABLY BE SOME NUISANCE CLOUD COVER FOR SOME PART OF THE NIGHT ACROSS EASTERN UPPER GIVEN SATELLITE TRENDS AND OVER WATER INSTABILITY. EVENTUALLY THINK CLOUD FOCUS WILL IMPACT NORTHEAST LOWER DURING THE PRE-DAWN HOURS ONCE LOW LEVEL FLOW VEERS AROUND TO NORTHEAST. AS FOR FROST POTENTIAL...NOT PLANNING ON ANY HEADLINES ACROSS NORTHERN LOWER AT THIS POINT FOR SEVERAL REASONS. DEW POINTS ARE STILL WELL INTO THE 40S/LOWER 50S AT MID AFTERNOON...AND AIRCRAFT SOUNDINGS SUGGESTS WE`VE ABOUT MAXED OUT ON HOW MUCH MOISTURE WILL MIX OUT OF THE BOUNDARY LAYER. WOULD BE MORE CONCERNED IF DEW POINTS WERE ALREADY IN THE 30S. THERE MAY ALSO BE JUST ENOUGH GRADIENT TO KEEP WINDS UP MOST OF THE NIGHT ACROSS NORTHEAST LOWER (THOUGH WINDS WILL PROBABLY DECOUPLE IN THE LOW SPOTS). AND THE AFOREMENTIONED CLOUD ISSUE ESPECIALLY EAST OF I-75. SO A PATCHY FROST MENTION INLAND SHOULD SUFFICE FOR NOW. WILL KEEP HEADLINE UP FOR EASTERN UPPER...THOUGH LIKE NORTHERN LOWER WOULD PREFER TO SEE LOWER DEW POINTS THIS AFTERNOON...AND CONCERNED ABOUT POTENTIAL EVENING CLOUD COVER. JPB && .LONG TERM.../ISSUED AT 342 PM/...THURSDAY AND BEYOND THURSDAY...GFS IS ADVERTISING THE MOISTURE OVER LAKE HURON AROUND 12Z AND THEN JUST A WEE BIT AT 18Z. WITH THE GFS OUTDOING THE NAM WITH THE LOW LEVEL CLOUDS OVER LAKE HURON, WILL GO WITH THE GFS IN THIS CASE. THEN A CLEARING TREND THROUGH THE DAY AS THE DRY AIR THAT IS ADVERTISED BY BOTH MODELS MOVING IN. THURSDAY NIGHT... RETURN FLOW WILL KEEP THE TEMPERATURES UP A BIT HIGHER, BUT CLOSE TO OR SLIGHTLY LOWER THAN GUIDANCE TEMPERATURES. WOULD EXPECT THAT THE TEMPERATURES WILL LEVEL OFF OVERNIGHT. CLOUDS WILL INCREASE AS WELL WITH THE APPROACH OF THE STORM SYSTEM. FRIDAY...MOISTURE INCREASES AS THE 700-500 MB LAYER RH INCREASES WITH THE FRONT APPROACHING, THE WARM FRONT LOOKS PRETTY WEAK AND THE DYNAMICS WITH THE SYSTEM IS NORTH, SO NO PRECIPITATION UNTIL FRIDAY EVENING AS THE COLD FRONT GOES THROUGH. THE CHANCE FOR SHOWERS AND THUNDERSTORMS IS MAINLY E UPPER AND THE TIP OF THE MIT OVERNIGHT. SATURDAY...THE COLD FRONT PASSES THROUGH N LOWER THROUGH THE AFTERNOON SO HAVE A CHANCE OF RAIN, HOWEVER, THE MODELS DON`T HAVE ANY QPF FOR THE TIME PERIOD. HOWEVER, WITH THE THERMAL PACKING AND THE WEAK 500 MB TROUGHING OVER THE STATE WOULD EXPECT THAT THERE WILL BE SCATTERED SHOWERS AND THUNDERSTORMS DURING THE AFTERNOON. THE SHOWALTER INDEX GOES TO -3C SO THERE IS A CHANCE FOR ELEVATED CONVECTION. AFTER THAT THE STABILITY INCREASES SO WILL GO WITH SCATTERED SHOWERS TAPERING OFF OVERNIGHT. EXTENDED (SUNDAY THRU WEDNESDAY)...SUNDAY THROUGH TUESDAY, THE SFC HIGH DRIFTS SLOWLY OVER THE GREAT LAKES PROVIDING DRY WEATHER THROUGH TUESDAY. IT LOOKS LIKE THAT MONDAY OR TUESDAY THE RETURN FLOW WOULD BEGIN SO THAT TEMPERATURES WILL BE ON AN UPSWING BY THE MID PART OF THE WEEK. WEDNESDAY, WITH THE 500 MB RIDGE AXIS OVER THE REGION WILL PROBABLY BE THE WARMEST OF THE WEEK. LUTZ && .MARINE.../ISSUED AT 342 PM/ TONIGHT...WILL DROP SMALL CRAFT ADVISORY FOR WHITEFISH BAY...JUST NOT HAPPENING UP THERE TODAY. ON THE LAKE HURON SIDE GREATEST THREAT FOR SMALL CRAFT CONDITIONS LOOKS TO BE SOUTH OF PRESQUE ISLE LIGHT...WITH SOME COASTAL CONVERGENCE AS WINDS BECOME MORE NORTHERLY THIS EVENING. HAVE HAD GUSTS TO 23KTS AT STURGEON POINT LIGHT THIS AFTERNOON. NO OTHER HEADLINES ANTICIPATED IN THE NEAR TERM. JPB && .AVIATION.../ISSUED AT 720 PM/...VALID FOR 00Z TAFS HIGH PRESSURE BUILDS IN TONIGHT. ONLY REAL ISSUES ARE FOG POTENTIAL AT PLN LATE TONIGHT...AND SHALLOW LAKE INDUCED SC INTO APN THURSDAY MORNING AS LOW LEVEL FLOW BECOMES NORTHEASTERLY. JPB/KAS && .APX WATCHES/WARNINGS/ADVISORIES... MI...FROST ADVISORY FROM 3 AM TO 8 AM EDT THURSDAY FOR MIZ008-015. LM...NONE. LH...SMALL CRAFT ADVISORY UNTIL 5 AM EDT THURSDAY FOR LHZ348-349. LS...NONE. && $$
AREA FORECAST DISCUSSION
NWS GAYLORD MI
342 PM EDT WED SEP 17 2008 .SYNOPSIS.../ISSUED AT 342 PM/ HIGH PRESSURE WILL FLOAT ACROSS THE REGION OVER THE NEXT 24 HOURS... FOLLOWED BY A WARM SOUTH/SOUTHWEST RETURN FLOW SETTING UP FOR THE END OF THE WEEK. MAIN BELT OF WESTERLIES WILL BE NORTH OF THE BORDER...BUT A COLD FRONT WILL TRY TO SNEAK IN FOR THE WEEKEND AND PERHAPS BRING OUR NEXT CHANCE FOR RAINFALL. JPB && .SHORT TERM.../ISSUED AT 342 PM/...TONIGHT HIGH PRESSURE SETTLING INTO THE UPPER GREAT LAKES TONIGHT...WITH THE BIGGEST ISSUE REVOLVING AROUND LOW TEMPERATURES AND FROST POTENTIAL. SOME DIURNAL CLOUDS HANGING AROUND THIS AFTERNOON WON`T BE AN ISSUE... BUT WITH COLDER AIR SINKING ACROSS THE REGION (850MB TEMPERATURES FALLING BELOW 4C). THERE WILL PROBABLY BE SOME NUISANCE CLOUD COVER FOR SOME PART OF THE NIGHT ACROSS EASTERN UPPER GIVEN SATELLITE TRENDS AND OVER WATER INSTABILITY. EVENTUALLY THINK CLOUD FOCUS WILL IMPACT NORTHEAST LOWER DURING THE PRE-DAWN HOURS ONCE LOW LEVEL FLOW VEERS AROUND TO NORTHEAST. AS FOR FROST POTENTIAL...NOT PLANNING ON ANY HEADLINES ACROSS NORTHERN LOWER AT THIS POINT FOR SEVERAL REASONS. DEW POINTS ARE STILL WELL INTO THE 40S/LOWER 50S AT MID AFTERNOON...AND AIRCRAFT SOUNDINGS SUGGESTS WE`VE ABOUT MAXED OUT ON HOW MUCH MOISTURE WILL MIX OUT OF THE BOUNDARY LAYER. WOULD BE MORE CONCERNED IF DEW POINTS WERE ALREADY IN THE 30S. THERE MAY ALSO BE JUST ENOUGH GRADIENT TO KEEP WINDS UP MOST OF THE NIGHT ACROSS NORTHEAST LOWER (THOUGH WINDS WILL PROBABLY DECOUPLE IN THE LOW SPOTS). AND THE AFOREMENTIONED CLOUD ISSUE ESPECIALLY EAST OF I-75. SO A PATCHY FROST MENTION INLAND SHOULD SUFFICE FOR NOW. WILL KEEP HEADLINE UP FOR EASTERN UPPER...THOUGH LIKE NORTHERN LOWER WOULD PREFER TO SEE LOWER DEW POINTS THIS AFTERNOON...AND CONCERNED ABOUT POTENTIAL EVENING CLOUD COVER. JPB && .LONG TERM.../ISSUED AT 342 PM/...THURSDAY AND BEYOND THURSDAY...GFS IS ADVERTISING THE MOISTURE OVER LAKE HURON AROUND 12Z AND THEN JUST A WEE BIT AT 18Z. WITH THE GFS OUTDOING THE NAM WITH THE LOW LEVEL CLOUDS OVER LAKE HURON, WILL GO WITH THE GFS IN THIS CASE. THEN A CLEARING TREND THROUGH THE DAY AS THE DRY AIR THAT IS ADVERTISED BY BOTH MODELS MOVING IN. THURSDAY NIGHT... RETURN FLOW WILL KEEP THE TEMPERATURES UP A BIT HIGHER, BUT CLOSE TO OR SLIGHTLY LOWER THAN GUIDANCE TEMPERATURES. WOULD EXPECT THAT THE TEMPERATURES WILL LEVEL OFF OVERNIGHT. CLOUDS WILL INCREASE AS WELL WITH THE APPROACH OF THE STORM SYSTEM. FRIDAY...MOISTURE INCREASES AS THE 700-500 MB LAYER RH INCREASES WITH THE FRONT APPROACHING, THE WARM FRONT LOOKS PRETTY WEAK AND THE DYNAMICS WITH THE SYSTEM IS NORTH, SO NO PRECIPITATION UNTIL FRIDAY EVENING AS THE COLD FRONT GOES THROUGH. THE CHANCE FOR SHOWERS AND THUNDERSTORMS IS MAINLY E UPPER AND THE TIP OF THE MIT OVERNIGHT. SATURDAY...THE COLD FRONT PASSES THROUGH N LOWER THROUGH THE AFTERNOON SO HAVE A CHANCE OF RAIN, HOWEVER, THE MODELS DON`T HAVE ANY QPF FOR THE TIME PERIOD. HOWEVER, WITH THE THERMAL PACKING AND THE WEAK 500 MB TROUGHING OVER THE STATE WOULD EXPECT THAT THERE WILL BE SCATTERED SHOWERS AND THUNDERSTORMS DURING THE AFTERNOON. THE SHOWALTER INDEX GOES TO -3C SO THERE IS A CHANCE FOR ELEVATED CONVECTION. AFTER THAT THE STABILITY INCREASES SO WILL GO WITH SCATTERED SHOWERS TAPERING OFF OVERNIGHT. EXTENDED (SUNDAY THRU WEDNESDAY)...SUNDAY THROUGH TUESDAY, THE SFC HIGH DRIFTS SLOWLY OVER THE GREAT LAKES PROVIDING DRY WEATHER THROUGH TUESDAY. IT LOOKS LIKE THAT MONDAY OR TUESDAY THE RETURN FLOW WOULD BEGIN SO THAT TEMPERATURES WILL BE ON AN UPSWING BY THE MID PART OF THE WEEK. WEDNESDAY, WITH THE 500 MB RIDGE AXIS OVER THE REGION WILL PROBABLY BE THE WARMEST OF THE WEEK. LUTZ && .MARINE.../ISSUED AT 342 PM/ TONIGHT...WILL DROP SMALL CRAFT ADVISORY FOR WHITEFISH BAY...JUST NOT HAPPENING UP THERE TODAY. ON THE LAKE HURON SIDE GREATEST THREAT FOR SMALL CRAFT CONDITIONS LOOKS TO BE SOUTH OF PRESQUE ISLE LIGHT...WITH SOME COASTAL CONVERGENCE AS WINDS BECOME MORE NORTHERLY THIS EVENING. HAVE HAD GUSTS TO 23KTS AT STURGEON POINT LIGHT THIS AFTERNOON. NO OTHER HEADLINES ANTICIPATED IN THE NEAR TERM. JPB && .AVIATION.../ISSUED AT 135 PM/...VALID FOR 18Z TAFS HIGH PRESSURE BUILDS IN TONIGHT...ONLY REAL ISSUES ARE FOG POTENTIAL AT PLN...AND SHALLOW LAKE INDUCED SC INTO APN THURSDAY MORNING AS LOW LEVEL FLOW BECOMES NORTHEASTERLY. && .APX WATCHES/WARNINGS/ADVISORIES... MI...FROST ADVISORY FROM 3 AM TO 8 AM EDT THURSDAY FOR MIZ008-015. LM...NONE. LH...SMALL CRAFT ADVISORY UNTIL 5 AM EDT THURSDAY FOR LHZ348-349. LS...NONE. && $$
AREA FORECAST DISCUSSION...UPDATED
NWS MARQUETTE MI
140 AM EDT TUE SEP 16 2008 UPDATED AVIATION DISCUSSION FOR 06Z TAFS .UPDATE... AN AREA OF MID CLOUDS FROM NE MN INTO WRN UPPER MI...PER IR LOOP...SUPPORTED BY 300K ISENTROPIC LIFT WAS SLOWLY SPREADING INTO CNTRL UPPER MI. HOWEVER...RADARS SHOWED PCPN FROM EARLIER THIS EVENING HAD MAINLY DISSIPATED. ONLY A FEW WEAK RETURNS WERE NOTED W OF KCMX. WITH 01Z KSAW TAMDAR SOUNDING SHOWING A VERY DRY LAYER BTWN 850-650 MB...NO MORE THAN AN TRANSIENT ISOLD SPRINKLE AT MOST IS EXPECTED. SO PCPN MENTION WAS REMOVED OVERNIGHT. && .SYNOPSIS... WATER VAPOR LOOP AND RUC ANALYSIS SHOWS AN AMPLIFIED RIDGE OVER THE WRN CONUS WITH A BROAD TROUGH OVER ERN CANADA...THE GREAT LAKES AND THE NE U.S. NORTHWEST FLOW BETWEEN THESE FEATURES REVEALS AN UPSTREAM SHORTWAVE OVER NRN MN. 800-600 MB FGEN AND 295-300K ISENTROPIC LIFT ASSOC WITH THIS SHORTWAVE AIDING AREA OF ISOLD SHRA/SPRINKLES OVER NRN MN THIS AFTERNOON. VIS SATELLITE STILL INDICATES LINGERING DIURNAL CU ACROSS MUCH OF UPR MI THIS AFTERNOON. && .SHORT TERM (TONIGHT AND TUESDAY)... THE MAIN CONCERN OF THIS FORECAST PACKAGE IS WHETHER SPRINKLES/ISOLD SHRA OVER NRN MN WILL REACH INTO WRN COUNTIES TONIGHT. MODELS SEEM TO INDICATE THAT FGEN FORCING AND ISENTROPIC ASCENT WILL CONTINUE TO MOVE INTO THE WRN FCST AREA LATER THIS EVENING AND OVERNIGHT ALTHOUGH FGEN FORCING APPEARS TO WEAKEN. GIVEN THAT THE RADAR LOOP SHOWS RETURNS STILL HOLDING TOGETHER...WILL INCLUDE LOW CHC POPS FOR SHRA OVER THE WRN U.P. AND WRN LAKE SUPERIOR THIS EVENING INTO THE OVERNIGHT HOURS. ALSO INCREASED CLOUD COVER OVER THESE AREAS AND BUMPED UP TEMPS A DEGREE OR TWO. DECIDED TO TAKE OUT MENTION OF PATCHY FROST OVER WRN INTERIOR WITH THE INCREASE IN CLOUDS EXPECTED. ISENTROPIC ASCENT ASSOC WITH ANOTHER SHORTWAVE MOVING ACROSS SCNTRL CANADA WILL BRING MORE MID-CLOUDS TO NRN TIER COUNTIES ON TUE. FILTERED SUNSHINE SHOULD ALLOW FOR MIXING NEAR 850 MB. WITH 850 MB TEMPS RISING TO AROUND 9-10C...LOOK FOR HIGHS IN THE LOWER 70S OVER THE WESTERN HALF AND THE UPPER 60S OVER THE EAST HALF. SRLY FLOW WILL KEEP TEMPS IN THE LOWER 60S NEAR LAKE MICHIGAN. .LONG TERM (TUE NIGHT THROUGH NEXT MON)... TUE NIGHT AND WED...AT 00Z WED...MULTIPLE SHRTWVS SHOULD BE LOCATED OVER NW ONTARIO AND NRN MANITOBA. AS THESE SHRTWVS DIVE SOUTHEAST THROUGH THE MEAN TROUGH OVER CENTRAL CANADA INTO THE GREAT LAKES...A COLD FRONT IS PROGGED TO DROP SOUTHEAST ACROSS THE CWA. TIMING OF THE FRONT IS STILL A LITTLE UNCERTAIN...WITH THE NAM AND REGIONAL CANADIAN ABOUT 3 HOURS SLOWER COMPARED TO THE GFS/UKMET/LOCAL WRF-ARW. FOR NOW HAVE TAKEN A COMPROMISE...THOUGH WOULD NOT BE SURPRISED FOR THE FASTER SOLUTION TO OCCUR. THE DIFFERENCE DOES NOT HAVE TOO MANY IMPLICATIONS ON WEATHER...THOUGH...EXCEPT FOR WEDNESDAY MORNING. INDICATIONS ARE FROM THE NAM...GFS AND LOCAL WRF-ARW RUNS OF SOME LOW CLOUDS AND LIKELY SOME LAKE ENHANCEMENT OCCURRING BEHIND THE COLD FRONT (SUGGESTIONS OF 850MB TEMPS LOWERING TO 2C). THE LOCAL WRF-ARW RUN ACTUALLY PRODUCES SOME UPSLOPE PCPN OVER THE NORTH CENTRAL WEDNESDAY MORNING. THE IDEA OF THESE LOW CLOUDS SEEMS REASONABLE...AND HAVE ADJUSTED CLOUD COVER UP. DID NOT INCLUDE ANY POPS...BUT HAVE INSERTED SOME DRIZZLE GIVEN THAT THERE IS UPSLOPE. OTHERWISE...THE REST OF THE PERIOD WILL BE DRY...DUE TO DRY AIR AHEAD OF THE FRONT AND THEN A CANADIAN HIGH BUILDING SE BEHIND THE FRONT OVER NORTHERN LAKE SUPERIOR. ACTUALLY...THIS HIGH COMBINED WITH DAYTIME MIXING SHOULD HELP TO MIX OUT THE CLOUDS WEDNESDAY AFTERNOON. A DECENT BREEZE (SW TO NW) BLOWING TUE NIGHT...COMBINED WITH THE LOW CLOUDS MOVING IN SHOULD KEEP LOW TEMPERATURES UP...AND HAVE RAISED THEM A FEW DEGREES. THESE LOW CLOUDS ALONG WITH AN ONSHORE WIND...AND THE COOL 850MB TEMPS NOTED ABOVE MEANS A COOL DAY ON WEDNESDAY. LOWERED HIGHS...ESPECIALLY ALONG LAKE SUPERIOR...WHERE READINGS SHOULD ONLY BE IN THE MID TO UPPER 50S. MID TO UPPER 60S ARE POSSIBLE OVER THE SOUTHERN U.P. WHERE NORTHERLY WINDS DOWNSLOPE AND MORE SUN OCCURS. WED NIGHT AND THU...UPPER FLOW IS PROGGED TO TURN FROM THE NW TO THE WNW DURING THIS PERIOD DUE TO THE SOUTH CENTRAL CANADA/GREAT LAKES TROUGH LIFTING OUT TO THE NORTHEAST. THIS MOTION ALLOWS THE HIGH THAT WAS BUILDING OVER NORTHERN LAKE SUPERIOR WEDNESDAY AFTN TO SHIFT INTO THE FAR EASTERN U.P. BY 12Z THU...AND THEN TO LAKE ONTARIO BY 00Z FRI. WED NIGHT WILL BE COOL GIVEN THE TRACK OF THE HIGH...A COOL DAY ON WEDNESDAY AND PRECIPITABLE WATER PROGGED TO FALL TO 0.4-0.5 INCHES. THE ONLY THING THAT CAN POSSIBLY STOP TO MUCH OF A FALL IS SOME HIGH CLOUDS MOVING ACROSS. HAVE LOWERED LOWS ABOUT 10 DEGREES FROM THE PREVIOUS FORECAST...GREATEST INLAND. THIS RESULTS IN THE MENTION OF PATCHY FROST ACROSS A LOT OF THE CWA. FURTHER LOWERING MAY BE REQUIRED...ESPECIALLY IF THE HIGH CLOUDS ARE NO LONGER EXPECTED. WOULD NOT BE SURPRISED TO SEE A FEW LOWS IN THE 20S. ON THU...COOL AIR LINGERS IN THE EASTERN CWA CLOSER TO THE HIGH...WITH 850MB TEMPS AT 18Z OF 4C AT ERY. ON THE OTHER HAND...RETURN FLOW IS SETTING UP NICELY OUT WEST ON INCREASING SOUTHERLY WINDS...WITH 850MB TEMPS NEAR 10C AT IWD AT 18Z. PLENTY OF SUN SHOULD OCCUR WITH A DRY AIRMASS IN PLACE...SO DEEP MIXING IS EXPECTED. THEREFORE...HAVE LOWERED HIGHS TO AROUND 60 OUT EAST BUT RAISED THEM TO AROUND 70 OUT WEST. THU NIGHT THROUGH MON...MODEL AGREEMENT THROUGH THE EXTENDED BTWN THE 00Z ECMWF/06Z GFS AND 00Z UKMET IS QUITE GOOD...WITH ALL BASICALLY NEARLY IDENTICAL UNTIL MONDAY WITH A TROUGH COMING INTO THE WEST COAST WHERE THE 00Z ECMWF IS FASTER. ONE INTERESTING ASPECT IS THAT THE 06Z GFS CAME INTO BETTER ALIGNMENT WITH THE 00Z ECMWF COMPARED TO ITS 00Z PREDECESSOR...WHICH SHOWED A LARGE TROUGH FROM CENTRAL CANADA INTO THE NORTHERN ROCKIES/NRN PLAINS AT 00Z TUE. THE 00Z GFS ENSEMBLES ALSO HAD THIS APPEARANCE. GIVEN THE FACT OF GOOD AGREEMENT BTWN THE 00Z ECMWF/06Z GFS/00Z UKMET...TEND TO LEAN TOWARDS THEIR SOLUTIONS...PARTICULARLY BECAUSE THE GFS ENSEMBLES ARE BOTH GENERALLY TOO PROGRESSIVE (DUE TO LOWER RESOLUTION COMPARED TO THE GFS) AND THEY ARE CLUSTERING A BIT AROUND THE 00Z GFS RUN. REGARDING DETAILS...THE UPPER LEVEL FLOW THROUGH THE PERIOD FEATURES A WNW FLOW ACROSS SOUTHERN CANADA AND THE NORTHERN U.S. AT THE START OF THE PERIOD...WHICH THEN BACKS TO NEARLY ZONAL BY 00Z SUN...AND THEN TO WEAK RIDGING BY LATER MONDAY AS THE TROUGH MOVES INTO THE WEST COAST. THIS PATTERN SETUP IS USUALLY DRY FOR UPPER MI...HOWEVER...A SWITCH FROM NEARLY ZONAL TO WEAK RIDGING MEANS WARM ADVECTION AND THAT CAN GENERATE SOME CONVECTION. THE GFS DOES PRODUCE PCPN LATE SAT THROUGH SUN AS A RESULT. THE ECMWF DOES AS WELL...BUT IS JUST TO OUR NORTH. THE REASON FOR THE DIFFERENCE IS THAT THE GFS SHOWS A COLD FRONT DROPPING SOUTH AND STALLING OVER UPPER MI ON SAT...WHEREAS THE ECMWF KEEPS IT TO THE NORTH. GIVEN THE FACT THAT THE COLD FRONT FORECAST FOR TUE NIGHT/WED WAS PROGGED TO GO THROUGH HERE FIRST BY THE GFS AND THEN BY THE ECMWF...HAVE DECIDED TO FOLLOW THE GFS SCENARIO. THIS MEANS THAT SAT WILL ALSO FEATURE COOLER TEMPERATURES NEAR LAKE SUPERIOR DUE TO ONSHORE FLOW BEHIND THE FRONT. OTHERWISE...DRY WEATHER IS FORECAST FOR THU NIGHT THROUGH SAT MORNING...AND SUN AFTN THROUGH MON. TEMPERATURES THROUGH THE PERIOD WILL BE ABOVE NORMAL...EXCLUDING NEAR THE SHORELINE ON SAT...THANKS TO 850MB TEMPS RUNNING GENERALLY AROUND 12C THROUGH THE PERIOD. ONE LAST ITEM TO NOTE IS THAT THE 00Z ECMWF DOES TRY TO BRING SOME PCPN INTO THE CWA THU NIGHT AND FRI...APPARENTLY AS A RESULT OF THE TUE NIGHT/WED COLD FRONT RETREATING NORTHWARD AS A WEAK WARM FRONT DURING THIS PERIOD. THE GFS SOMEWHAT SHOWS THIS AS WELL...THOUGH IT ALLOWS THE FRONT TO FIZZLE OUT. HAVE GONE WITH THE GFS IDEA FOR NOW. NEW 12Z ECMWF THROWS A LITTLE CONFIDENCE AND A WRINKLE INTO THE EXTENDED. IT NOW SHOWS THE COLD FRONT DROPPING SOUTH INTO THE CWA ON SAT AS THE 06Z GFS SHOWED...SO THE PLAN ABOVE LOOKS GOOD. HOWEVER...THE NEW ECMWF ALSO DIVES THE FRONT FARTHER SOUTH BY AMPLIFYING A TROUGH OVER EASTERN CANADA...RESULTING IN A CANADIAN HIGH BUILDING INTO ONTARIO. THIS WOULD RESULT IN COOLER TEMPS ON SUN AND MON...ESPECIALLY NEAR THE LAKE SUPERIOR SHORE. WILL WAIT ANOTHER CYCLE BEFORE CHANGING. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... EXPECT VFR CONDITIONS THROUGH THE FCST PERIOD WITH SOME WAA MID CLOUDS MOVING THROUGH OVERNIGHT INTO THE EARLY MORNING. LOW PRESSURE MOVING THROUGH LAKE SUPERIOR IN THE EVENING WILL DRAG A COLD FRONT THROUGH NW UPPER MI WITH WINDS VEERING FROM WSW TO NW AT KCMX. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... WINDS HAVE DIMINISHED SIGNIFICANTLY ON LAKE SUPERIOR COMPARED TO THIS TIME YESTERDAY...THANKS TO A HIGH PRESSURE RIDGE IN PLACE. WINDS ARE NOW BELOW 20 KT. HOWEVER...A TROUGH APPROACHING FROM WESTERN MN WILL STRENGTHEN SOUTHERLY WINDS ON THE LAKE...UP TO 25 KT BY TUE MORNING. FURTHER STRENGTHENING TO 30 KT IS EXPECTED TUE AFTN INTO TUE EVENING AS A COLD FRONT DROPS SE OUT OF CANADA. BEHIND THE FRONT...NORTHERLY WINDS SHOULD INCREASE TO AT LEAST 25 KT WED MORNING OVER EASTERN LAKE SUPERIOR. WINDS WILL THEN DECREASE TO BELOW 20 KT FOR WED AFTN INTO THU MORNING AS CANADIAN HIGH PRESSURE MOVES ACROSS. AS THIS HIGH SHIFTS INTO THE EASTERN GREAT LAKES THU AFTN AND ANOTHER FRONT DROPS SE OUT OF CANADA...EXPECT SOUTHERLY WINDS TO INCREASE TO 25 KT THU AFTN AND TO 30 KT THU NIGHT THROUGH FRI. COLD FRONT CROSSES LAKE SUPERIOR FRI NIGHT...WITH A WIND SWITCH TO THE NE ON SAT. THE NE WINDS COULD REACH 25 KT...GREATEST ON WESTERN LAKE SUPERIOR. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR...NONE. LAKE MICHIGAN...NONE. && $$ SYNOPSIS/SHORT TERM...VOSS LONG TERM...AJ AVIATION...JLB MARINE...AJ
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
415 AM PDT THU SEP 18 2008 ...UPDATED AVIATION SECTION... .SHORT TERM... OFFSHORE TRENDS AND MUCH ABOVE NORMAL 850 MB HUMIDITIES HAVE DONE A NUMBER ON THE MARINE LAYER WITH ONLY PATCHY LOW CLOUDS AROUND THE L.A. AND CATALINA COASTS. SMALL WORRY WITH THOSE HIGH 850 DEW POINTS INTERACTING WITH A SMALL DEFORMATION ZONE AND BUBBLING UP SOME CONVECTION EARLY THIS MORNING...BUT SATELLITE SHOWS NO ACTIVITY AND KEPT MENTION OUT OF THE FORECAST BUT WILL HAVE TO MONITOR. THIS AFTERNOON THAT SAME MOISTURE WILL CAUSE PARTLY CLOUDY SKIES AND A SLIGHT CHANCE OF TSTMS OVER THE VTA AND LA MTNS AS WELL AS THE ANTELOPE VALLEY. MDLS CONTINUE TO SHOW NO MARINE LAYER TONIGHT AS THEY HAVE BEEN FOR THE PAST FEW DAYS AND GIVEN THE CLEAR SKIES AT THE MOMENT WILL KEEP SKIES CLEAR. TEMPS WILL BE VERY SIMILAR TO TODAYS VALUES BUT SINCE THERE WILL BE NO MID LEVEL MOISTURE THERE WILL BE NO TSTM THREAT. IN THE WAKE OF A WEAK TROF ONSHORE FLOW SHOULD INCREASE ENOUGH TO BRING MARINE CLOUDS BACK TO THE CENTRAL COAST. THERE IS A CHANCE OF LOW CLOUDS SOUTH OF POINT CONCEPTION BUT FOR NOW WILL LEAVE THEM OUT. LOOK FOR A WEAK SUNDOWNER BOTH TONIGHT AND FRIDAY NIGHT WITH A LITTLE NW UPPER PUSH AND A MINUS 3 SMX-SBA GRADIENT. .LONG TERM... MEDIUM RANGE MDLS HAVE FINALLY COME INTO SOME SORT OF AGREEMENT FOR THE EXTENDED FORECAST. THE WEEKEND LOOKS FAIRLY BLAND WITH A FLAT TROF SITTING OVER THE WEST COAST. THIS SHOULD BRING THE MARINE LAYER BACK TO THE COASTAL SECTIONS AND MAYBE SOME PATCHES INTO THE COASTAL VLYS. A LITTLE LOWER HGTS AND STRONGER ONSHORE FLOW WILL DROP TEMPS A FEW MORE DEGREES. THE TROF SHARPENS AND DIVES SOUTH MONDAY AND EXITS EARLY TUESDAY AND THIS SHOULD LIFT THE MARINE LAYER INTO THE VLYS. A HIGH WILL BUILD INTO NEVADA IN THE WAKE OF THIS TROF AND BY WEDNESDAY THE FIRST OFFSHORE EVENT OF THE SEASON COULD SHAPE UP. BUT THE GFS IS A LITTLE OFFSHORE HAPPY AND THIS FORECAST COULD CHANGE BY THEN. && .AVIATION... 18/1100Z. LATEST ACARS SHOWS LITTLE IF ANY MARINE LAYER...BUT SATELLITE SHOWS SOME PATCHY CLOUDS IN THE SANTA MONICA BASIN AND THESE CLOUDS WILL AFFECT KLGB TO KNTD AT TIMES THROUGH MID MORNING. THERE IS A 10 PERCENT CHC OF A TSTM THIS MORNING OVER L.A. COUNTY. THERE WILL BE BUILD UPS OVER THE L.A. MTNS THIS AFTERNOON WITH A 20 PERCENT CHANCE OF TSTMS MID AFTERNOON THROUGH EARLY EVENING. MARINE LAYER CLOUDS RETURN TONIGHT IS QUESTIONABLE...MORE LIKELY ON THE CENTRAL COAST AND TO THE L.A. COAST AFTER 12Z. KLAX...GOOD CONFIDENCE IN 16Z BURN OFF PLUS OR MINUS ONE HOUR. 30 PERCENT CHANCE OF MVFR CLOUDS FORM 08Z TO 12Z TONIGHT. KBUR...HIGH CONFIDENCE IN CAVU TAF. A 20 PERCENT CHANCE OF 5SM IN HZ IN THE EARLY MORNING. && .LOX WATCHES/WARNINGS/ADVISORIES... SMALL CRAFT ADVISORY (SEE LAXMWWLOX). && $$ PUBLIC...RORKE AVIATION...BRUNO WWW.WEATHER.GOV/LOSANGELES
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
1021 AM EDT THU SEP 18 2008 .SYNOPSIS... COLD CANADIAN HIGH PRESSURE RETURNS TODAY AND THRU THE BEGINNING OF THE WEEKEND. A KILLING FREEZE AND FROST IS EXPECTED EARLY FRIDAY MORNING. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 1020 AM EDT THURSDAY...FORECAST SO FAR PRETTY MUCH ON TRACK AS LAST NITES FRONT HAS PUSHED OFFSHORE ALLOWING HIGH PRESSURE TO BUILD IN. CAA STILL ONGOING AND THIS IS HELPING TO ALLOW SOME SMALL CU TO BUBBLE UP. AIRCRAFT SOUNDING OUT OF BTV JUST BEFORE 12Z SHOWED 850MB TEMPS ALREADY DOWN TO 0.9C HERE...WITH 12Z MANIWAKI SOUNDING SHOWING -3C 850 TEMPS THERE. SFC TEMPS RUNNING IN THE L-M50S AREAWIDE AND SHOULD EEK UP A FEW MORE DEGREES AS SURFACE HEATING BATTLES THE CAA. WE MAY BE A TAD HIGH ON AFTN HIGHS...BUT DONT FEEL ITS NEEDING ANY UPDATE AT THIS TIME. MAIN ISSUE WILL WORK ON TODAY WILL BE OVERNIGHT LOWS. CERTAINLY WILL BE THE COLDEST NITE SO FAR IN THE YOUNG FALL SEASON WITH WIDESPREAD FROST...ESP AWAY FROM WARMING INFLUENCES OF THE LARGER LAKES...AND AREAS THAT GO SUB-FREEZING. CURRENTLY FCSTING NEAR RECORD LOWS AT A NUMBER OF LOCATIONS...AND WILL NEED TO EVALUATE 12Z GUIDANCE TO SEE IF WE WILL NEED TO MODIFY ASPECTS OF THAT FORECAST. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/... AS OF 430 AM EDT THURSDAY...AS STRONG COLD HIGH PRESSURE CRESTS ACROSS THE REGION TONIGHT...WITH A DRY AIR MASS IN PLACE IDEAL RADIATIONAL COOLING CONDITIONS SET UP REGION WIDE. CLEAR SKIES...AND LIGHT TO CALM WINDS WILL ALLOW TEMPERATURES TO DROP BELOW FREEZING ACROSS MOST OF THE FORECAST AREA. ONLY EXCEPTION WILL BE GRAND ISLE COUNTY IN VERMONT...AND AREAS BORDERING LAKE CHAMPLAIN. THE LAKE WILL HELP TO KEEP THESE AREAS INSULATED FROM THE 66 DEGREE LAKE...MIN TEMPERATURES SHOULD HOLD TO THE MID TO UPPER 30S IN THIS AREA. FREEZE WARNING HAS BEEN ISSUED FOR ALL AREAS MINUS GRAND ISLE COUNTY. COLDEST SPOT IN OUR CWA WILL BE ACROSS THE NORTHERN ADIRONDACKS AND COLDER VALLEYS OF THE NORTHEAST KINGDOM...WHERE LOWS WILL BE IN THE 20S. SURFACE HIGH WILL SLIDE EAST OF THE CWA ON FRIDAY...BUT RIDGE AXIS WILL EXTEND BACK INTO THE OHIO VALLEY AND MID ATLANTIC REGION. 850 TEMPS WILL BE ON THE INCREASE THROUGH THE END OF THE SHORT TERM FORECAST. SLIGHT GRADIENT AND SCATTERED CLOUDS WILL KEEP TEMPERATURES FROM PLUNGING AGAIN ON FRIDAY NIGHT. SATURDAY WILL BE ANOTHER DAY WITH HIGH PRESSURE DOMINATING THE WEATHER ALTHOUGH 850 TEMPS WILL NOW BE IN THE DOUBLE DIGITS...SO NOT AS COOL. ALSO...AS HIGH PRESSURE SLIDES AWAY FROM THE AREA THE REGION WILL BE UNDER SW FLOW AND TEMPS WILL BE WARMER. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... AS OF 445 AM EDT THURSDAY...FAIRLY QUIET EXTENDED PERIOD AS WELL WITH JUST A FRONTAL PASSAGE SATURDAY NIGHT INTO SUNDAY MORNING...FOLLOWED BY MORE HIGH PRESSURE. COLD FRONT DROPS SOUTH FROM CANADA ON SATURDAY NIGHT...BUT WITH LIMITED MOISTURE HAVE GONE WITH JUST SLIGHT CHANCE TO LOW CHANCE POPS...MAINLY ACROSS OUR NORTHERN ZONES. HIGH PRESSURE WILL AGAIN BUILD INTO THE AREA AND THE REST OF THE FORECAST WILL BE QUIET AND DRY WITH SEASONABLE TEMPERATURES. WITH MOSTLY CLEAR SKIES AND LIGHT WINDS...GOOD RADIATIONAL COOLING SHOULD SET UP EACH NIGHT. THE COLDEST READINGS OF THE EXTENDED WILL COME MONDAY NIGHT AS MOST LOCATIONS DIP INTO THE LOWER TO MID 30S. && .AVIATION /14Z THURSDAY THROUGH MONDAY/... THROUGH 12Z FRIDAY...A COLD FRONT SWEEPING BISECTING THE FORECAST AREA FROM ENE-WSW AT 06Z IS ASSOCIATED WITH A BAND OF RAIN SHOWERS AND NARROW ZONE OF IFR CONDITIONS OVER NRN VT/NERN NY ATTM. GUSTY NLY WINDS UP TO 25 KTS ARE ALSO PREVALENT NORTH OF THE FRONTAL BOUNDARY. EXPECT THESE CONDITIONS TO AFFECT MPV AND RUT THROUGH 08-09Z...FOLLOWED BY DIMINISHING WIND AND A GRADUAL IMPROVEMENT TO CIGS/VSBY ACROSS THE NORTH COUNTRY TOWARD DAYBREAK. THE PRESSURE GRADIENT WILL GRADUALLY WEAKEN DURING THE DAYLIGHT HRS AS A STRONG SFC ANTICYCLONE BUILDS SEWD ACROSS SERN ONTARIO AND THE EASTERN GREAT LAKES. DESPITE THIS...LOW-LEVEL COLD ADVECTION AND CLEARING SKIES WILL CONTRIBUTE TO WELL-MIXED CONDITIONS AND SOME GUSTS 15-20 KTS DURING THE DAYLIGHT HRS. CLOUDS WILL BE LIMITED TO FEW- SCT035-040. CLOUDS WILL DISSIPATE QUICKLY 22-23Z AND WINDS WILL BECOME LIGHT AND VARIABLE AROUND 23-00Z. CALM WINDS AND CLEAR SKIES WILL BE THE RULE 00-12Z FRIDAY. DENSE VLY FOG WILL DEVELOP IN A FEW SPOTS AFTER MIDNIGHT...ESPECIALLY AT MPV AND ALONG THE CT RIVER VALLEY. 12Z FRIDAY THROUGH MONDAY...THE ONLY WEATHER CONCERN THROUGH THE EXTENDED AVIATION PERIOD WILL BE ANOTHER COLD FRONT SATURDAY NIGHT THROUGH SUNDAY. THIS FRONT WILL ALSO HAVE LIMITED MOISTURE...SO EXPECT CONDITIONS TO REMAIN MVFR AT MOST SITES WITH SCATTERED IFR POSSIBLE. OTHERWISE...THE REST OF THE PERIOD WILL BE VFR WITH FOG DEVELOPING AT THE FAVORED SITES EACH MORNING. IFR/VLIFR CAN BE EXPECTED IN ANY FOG THAT FORMS. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...FREEZE WARNING FROM MIDNIGHT TONIGHT TO 8 AM EDT FRIDAY FOR VTZ002>012-016>019. FROST ADVISORY FROM MIDNIGHT TONIGHT TO 8 AM EDT FRIDAY FOR VTZ001. NY...FREEZE WARNING FROM MIDNIGHT TONIGHT TO 8 AM EDT FRIDAY FOR NYZ026>031-034-035-087. && $$ SYNOPSIS...NEILES NEAR TERM...NASH SHORT TERM...NEILES LONG TERM...NEILES AVIATION...BANACOS
AREA FORECAST DISCUSSION
NWS SEATTLE WA
830 AM PDT THU SEP 18 2008 .SYNOPSIS...LOW LEVEL ONSHORE FLOW BROUGHT MARINE STRATUS INTO WESTERN WASHINGTON EARLY THIS MORNING. THE CLOUDS WILL BURN BACK TOWARD THE COAST THIS AFTERNOON THEN MOVE INLAND AGAIN OVERNIGHT THROUGH FRIDAY MORNING. A WEAK UPPER TROUGH WILL MOVE THROUGH THE AREA FRIDAY NIGHT AND SATURDAY. AN UNSETTLED WEATHER PATTERN MAY PERSIST INTO NEXT WEEK. && .SHORT TERM...STRATUS COVERS MOST OF WESTERN WASHINGTON AND EXTENDS UP THE CASCADE VALLEYS. HOWEVER THE CASCADE MOUNTAINS ARE BASICALLY IN THE CLEAR. OLYMPICS WOULD BE CLEAR TOO EXCEPT THERE IS A FAIR BIT OF CIRRUS OVERHEAD. PRESSURE GRADIENTS HAVE TURNED SLIGHTLY OFFSHORE SO THE STRATUS HAS PROBABLY PENETRATED AS FAR AS IT WILL GO TODAY. EXPECT CLEARING LATE THIS AFTERNOON...EARLY THIS EVENING FOR SOME WESTERN AREAS. TEMPS WILL BE DOWN ABOUT 5 DEGREES FROM YESTERDAY. PATTERN WILL BE SIMILAR FRIDAY WITH MORNING CLOUDS AND AFTERNOON SUN. THE WEEKEND WILL NOT ONLY HAVE MARINE STRATUS...BUT ALSO SOME HIGHER CLOUDS ASSOCIATED WITH AN UPPER LEVEL TROUGH SWINGING THROUGH THE AREA. HIGH TEMPS WILL BE IN THE 60S. BOTH THE GFS AND NAM HAVE CHANCE POPS FRIDAY NIGHT THROUGH SUNDAY. THIS IS NOT A BIG STORM BY ANY MEANS BUT SCATTERED LIGHT SHOWERS ARE DEFINITELY A POSSIBILITY AND THEY ARE IN THE FORECAST. BURKE .LONG TERM...PREVIOUS DISCUSSION...NO CHANGE TO EXTENDED FORECAST THIS SHIFT AND FORECAST IS CLOSE TO CLIMO WHICH IS OKAY AT THIS TIME RANGE. IF THE MODELS HOLD TO THE 00Z SOLUTION HOWEVER THEN HIGHER POPS MIGHT BE COMING FOR SUNDAY AND AGAIN BY WED. GFS HAS UPPER TROF SUN WITH SHOWERS...AGAIN THE WRF EXTENSION LOOKS WET W/ A HALF AN INCH OR MORE IN THE CASCADES AND FOOTHILLS AND NORTH INTERIOR. THE GFS HAS ANOTHER TROF HANGING BACK IN THE NE PAC WHILE THE ECMWF SHOWS A MORE CONSOLIDATED UPPER TROF MOVING THRU THE REGION ON MONDAY. THEN BOTH MODELS SHOW A DIRTY RIDGE JUST OFFSHORE W/ 500MB IN 570S. THE 00Z GFS HAS A SOAKING RAIN EVENT IN THE MOUNTAINS BY WED. WRF EXTENSION SHOWS 1-2.5" IN THE MTNS IN 24HRS BUT LESS THAN A QUARTER INCH LOWLANDS. FORECAST MAY HAVE SOME CATCHING UP TO DO IF THE GFS PERSISTS WITH THIS IDEA. THE ECMWF IS SLOWER AND TAKES MORE OF THE MOISTURE INTO B.C. BEFORE BRINGING RAIN INTO WRN WA THU. THAT ADDRESSES THE WETTER POSSIBILITY. BUT IT IS ALSO A GOOD GUESS AT THIS TIME RANGE THAT THE MODELS WILL NOW AMPLIFY THE FLOW A BIT MORE AND THAT COULD KEEP SYSTEMS GOING TO THE NORTH OF WA. AS I SAID FOR NOW FORECAST LOOKS FINE WITH SOME CLOUDS AND TEMPS IN THE 60S. 19 && .AVIATION...LOWLANDS REMAINED SOCKED IN THIS MORNING AS MARINE LAYER MOVED IN OVERNIGHT. STRONG LOW LEVEL INVERSION KEEPING CIGS QUITE LOW WITH IFR TO LIFR CONDITIONS REPORTED ACROSS THE INTERIOR. ESTIMATED THICKNESS OF THE STRATUS LAYER IS 3000FT OVR PUGET SOUND ...BASED ON RECENT PILOT REPORTS AND ACARS SOUNDINGS. CEILING OVER THE INTERIOR WILL GRADUALLY LIFT WITH BKN020-030 SKIES THIS AFTERNOON 20-22Z...THEN SCT CLOUDS DURING THE LATE AFTERNOON AND EARLY EVENING. THE COAST HOWEVER SHOULD REMAIN CLOUDY AND MVFR. LOW CLOUDS WILL FILL BACK IN OVERNIGHT AS ONSHORE FLOW INCREASES. 33 KSEA...IFR CONDITIONS WILL CONTINUE THROUGH THE MORNING WITH LOWER VIS AT TIMES IN BR. CIGS WILL GRADUALLY LIFT TODAY WITH A BREAKOUT EXPECTED LATE AFTERNOON AND EARLY EVENING. STRATUS WILL FILL BACK IN OVERNIGHT HOWEVER CIGS WILL BE HIGHER...BUT STILL IN THE MVFR RANGE. WINDS TODAY EXPECTED TO REMAIN SOUTHERLY. 33 && .MARINE...ONSHORE FLOW ACROSS W WA WILL CONTINUE TODAY WITH HI PRES ALONG THE COAST AND LOWER PRES E OF THE CASCADES. STRONGEST WINDS WILL BE FOUND THROUGH THE STRAIT OF JUAN DE FUCA WITH WLY WINDS RISING TO 15 TO 25 KT THIS AFTERNOON. ONSHORE FLOW PATTERN WILL PERSIST OVER THE NEXT SEVERAL DAYS. 33 && .FIRE WEATHER...THE COOL...HUMID AND STABLE INFLUENCE OF THE MARINE LAYER EXTENDS UP TO ABOUT 3500 TO 4000 FEET THIS MORNING. CONDITIONS ARE STILL DRY ABOVE THAT...BUT THE KUIL AND KSLE SOUNDINGS FROM 12Z BOTH SHOWED MID-LEVEL HAINES INDEX OF 4. EVEN ABOVE THE MARINE LAYER...THE AIR MASS SHOULD CONTINUE TO SLOWLY STABILIZE TODAY. AS A RESULT...THE RED FLAG WARNING WAS CANCELLED AROUND 730 AM THIS MORNING. HANER && .SEW WATCHES/WARNINGS/ADVISORIES... SMALL CRAFT ADVISORY CENTRAL AND EAST STRAIT OF JUAN DE FUCA. && $$ WEATHER.GOV/SEATTLE