Forecast Discussions mentioning "ACARS", "MDCRS", "AIRCRAFT", "TAMDAR", or "AMDAR" received at FSL on 12/25/06

.SYNOPSIS... GUSTY OFFSHORE WINDS THROUGH AND BELOW MOUNTAIN PASSES AND CANYONS WILL DIMINISH TODAY AS A HIGH PRESSURE RIDGE BUILDS ALOFT. THE RIDGE WILL BRING FAIR WEATHER THROUGH MONDAY WITH WARMER DAYS...BUT CONTINUED COOL NIGHTS. THE WEATHER LOOKS EXCEPTIONALLY NICE FOR BOTH CHRISTMAS EVE AND CHRISTMAS DAY. A WEAK TROUGH OF LOW PRESSURE MAY BRING A SOME LIGHT PRECIPITATION TUESDAY NIGHT AND WEDNESDAY... OTHERWISE FAIR AND DRY WEATHER SHOULD CONTINUE THROUGH NEXT WEEK.

&&

.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES...

.SHORT TERM (TODAY THROUGH MONDAY)...

KSOX RADAR DATA IS UNAVAILABLE UNTIL APPROX. THU.

WINDS BEGINNING TO PICK UP THIS MORNING WITH GUSTS FROM 30 TO 40 MPH REPORTED LOCALLY IN THE SANTA ANA MTNS AND INLAND EMPIRE. ACARS SOUNDINGS THIS MORNING INDICATE SOME POTENTIAL CONTINUES WITH MID-LEVEL WINDS CLOSE TO 40 KTS. IF THIS MIXES DOWN LATER THIS MORNING...SOME WIND GUSTS CLOSE TO 50 MPH WILL BE POSSIBLE IN THE WINDIER SPOTS...SO THE WIND ADVISORY/WARNING WILL REMAIN IN EFFECT FOR AWHILE LONGER. IF NO SIGNIFICANT PICK-UP IS OBSERVED OVER THE NEXT HOUR...THE ADVISORY/WARNING MAY BE DROPPED.

FOR SUNDAY AND MONDAY...HIGH PRESSURE WILL HOLD OVER SOUTHERN CALIFORNIA. SUPPORT FOR OFFSHORE WINDS IS NOTICEABLY WEAKER WITH THE SURFACE HIGH CENTERED FARTHER EAST...OVER UTAH AND COLORADO. THIS SHOULD SUPPORT ONLY LOCAL MODERATE OFFSHORE WINDS BELOW PASSES AND CANYONS. EXPECT FAIR AND WARMER DAYS...BUT CONTINUED COOL NIGHTS. THIS SHOULD RESULT IN THE TYPE OF WEATHER SOCAL IS FAMOUS FOR THIS TIME OF YEAR...EXCEPTIONAL!

&&

.LONG TERM (TUESDAY THROUGH FRIDAY)... A FAST MOVING TROUGH OF LOW PRESSURE...IN WEST NORTHWEST FLOW...MAY BRING A PERIOD OF LIGHT PRECIPITATION SOME TIME IN THE LATE TUESDAY THROUGH EARLY WEDNESDAY TIME FRAME. GLOBAL MODELS ARE TRENDING STRONGER WITH THE HIGH PRESSURE TO BUILD BEHIND THIS TROUGH FOR THE LATTER HALF OF NEXT WEEK...SOMEWHAT SIMILAR TO THE SEQUENCE OF EVENTS FOR FRIDAY AND SATURDAY OF THIS WEEK. A PERIOD OF OFFSHORE IS ALSO POSSIBLE THURSDAY INTO FRIDAY BASED ON THE LATEST MODEL TRENDS.

&&

.AVIATION... ONLY AVIATION CONCERN TODAY IS OCCASIONAL SEVERE TURBULENCE/LOW LEVEL WIND SHEAR DUE TO NORTH-NORTHEAST WINDS 35-40 KNOTS FL020-FL100. BY 1300 PST/2100 UTC WIND SPEEDS IN THIS LAYER ARE EXPECTED TO SUBSIDE TO 25 KNOTS AND BY 1600 PST/000O UTC...DROP TO 20 KNOTS OR LESS. WEAK NORTHEAST WIND EXPECTED TO CONTINUE THROUGH CHRISTMAS EVE. DO NOT EXPECT RETURN OF MARINE LAYER UNTIL LATE MONDAY.

&&

.MARINE... LARGE NORTHWEST SWELL SLOWLY SUBSIDING...INFREQUENT SETS AROUND 10 FEET STILL POSSIBLE ALONG SAN DIEGO COUNTY COAST TODAY...MARINERS MAY ALSO ENCOUNTER BREAKING WAVES ACROSS HARBOR AND BAY ENTRANCES THIS AFTERNOON DURING THE LOW TIDE. AM CONSIDERING ADJUSTING END TIME OF HIGH SURF ADVISORY FOR SAN DIEGO COUNTY COAST TO COINCIDE WITH SURF FORECAST ISSUANCE TIME SUNDAY MORNING...0200 PST VERSUS 0700 PST.

&&

.SGX WATCHES/WARNINGS/ADVISORIES... CA...WIND ADVISORY UNTIL 2 PM PST THIS AFTERNOON FOR ORANGE COUNTY COASTAL AREAS-RIVERSIDE COUNTY MOUNTAINS-SAN BERNARDINO COUNTY MOUNTAINS-SAN DIEGO COUNTY MOUNTAINS.

HIGH WIND WARNING UNTIL 2 PM PST THIS AFTERNOON FOR SAN BERNARDINO AND RIVERSIDE COUNTY VALLEYS-THE INLAND EMPIRE- SANTA ANA MOUNTAINS AND FOOTHILLS.

HIGH SURF ADVISORY UNTIL 7 AM PST SUNDAY FOR SAN DIEGO COUNTY COASTAL AREAS.

PT...NONE.

&&

$$

PUBLIC...JAD/MARTIN AVIATION/MARINE...BALFOUR

NWS ON THE WEB AT WEATHER.GOV/SANDIEGO

.SYNOPSIS... SURFACE HIGH PRESSURE OVER NEVADA AND STRONG NORTH WINDS ALOFT WILL BRING MODERATE TO STRONG SANTA ANA WINDS THIS MORNING...DECREASING THIS AFTERNOON. BUILDING HIGH PRESSURE WILL BRING FAIR WEATHER THROUGH MONDAY WITH WARM DAYTIME TEMPERATURES AT LOWER ELEVATIONS AND COOL NIGHTTIME TEMPERATURES. A FAST MOVING TROUGH OF LOW PRESSURE MAY BRING A SLIGHT CHANCE OF LIGHT PRECIPITATION SOME TIME FROM LATE TUESDAY THROUGH EARLY WEDNESDAY. HIGH PRESSURE WILL BRING FAIR AND WARMER WEATHER FOR THE LATTER HALF OF NEXT WEEK.

&&

.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES...

.SHORT TERM (TODAY THROUGH MONDAY)... SURFACE HIGH PRESSURE OVER THE GREAT BASIN AND STRONG NORTH WINDS ALOFT ON THE BACK SIDE OF THE CLOSED UPPER LOW OVER NORTHERN MEXICO WILL BRING MODERATE TO STRONG SANTA ANA WINDS THIS MORNING... DECREASING THIS AFTERNOON. RECENT ACARS SOUNDINGS STILL SHOW THE CRITICAL INGREDIENTS FOR HIGH WIND WARNING THRESHOLD GUSTS IN THE WINDIER LOCATIONS THIS MORNING WITH A STRONG SUBSIDENCE INVERSION NEAR 700 MB...FAVORABLE FOR MOUNTAIN WAVE DEVELOPMENT...AND MAX WINDS IN THE LAYER BELOW THE INVERSION OF AROUND 50 KT. THE NAM CONTINUES TO SHOW MAX SUPPORT FOR OFFSHORE WINDS AROUND 12Z...THEN A SLOW DECREASE THROUGH THE MORNING HOURS. THE STRENGTH AND COVERAGE OF GUSTS HAS DECREASED SOMEWHAT THE PAST FEW HOURS...CONSISTENT WITH SOME DECOUPLING WITH THE NOCTURNAL RADIATIONAL INVERSION. HOWEVER...THERE CONTINUE TO BE OCCASIONAL GUST REPORTS TO AROUND AROUND 50 MPH. STRONGER WINDS SHOULD BEGIN TO SURFACE AFTER SUNRISE AND BECOME MORE WIDESPREAD THROUGH MID MORNING. THEREAFTER...WINDS SHOULD GRADUALLY SUBSIDE THROUGH MID AFTERNOON AS SUPPORT FOR THE OFFSHORE WINDS WEAKENS. TEMPERATURES IN WIND PROTECTED AREAS WILL START OUT QUITE COOL THIS MORNING WITH A WARMER START FOR AREAS WHERE MIXING FROM THE OFFSHORE WINDS HAS OCCURRED. GREATEST WARMING TODAY WILL BE FROM THE COAST INLAND TO THE LOWER COASTAL VALLEYS WHERE GREATEST DOWNSLOPE WARMING OCCURS.

FOR SUNDAY AND MONDAY...HIGH PRESSURE WILL HOLD OVER SOUTHERN CALIFORNIA. SUPPORT FOR OFFSHORE WINDS IS NOTICEABLY WEAKER FOR SUNDAY WITH ONLY LOCAL AND WEAKER OFFSHORE WINDS. LATEST GFS ON SUNDAY NIGHT AND MONDAY HAS STRONGER SURFACE HIGH PRESSURE CENTERED OVER NEVADA. WINDS ALOFT ARE WEAKER THAN TODAY. WITH THE CURRENT GFS SOLUTION...THERE COULD BE SOME LOCAL ADVISORY STRENGTH WINDS BELOW PASSES AND CANYONS MONDAY MORNING. DAYTIME TEMPERATURES SHOULD CLIMB TO ABOVE SEASONAL AVERAGES SUNDAY AND MONDAY WITH EXCEPTIONAL NICE WEATHER FOR BOTH DAYS.

&&

.LONG TERM (TUESDAY THROUGH FRIDAY)... A FAST MOVING TROUGH OF LOW PRESSURE...IN WEST NORTHWEST FLOW...MAY BRING A PERIOD OF LIGHT PRECIPITATION SOME TIME IN THE LATE TUESDAY THROUGH EARLY WEDNESDAY TIME FRAME. GLOBAL MODELS ARE TRENDING STRONGER WITH THE HIGH PRESSURE TO BUILD BEHIND THIS TROUGH FOR THE LATTER HALF OF NEXT WEEK...SOMEWHAT SIMILAR TO THE SEQUENCE OF EVENTS FOR FRIDAY AND SATURDAY OF THIS WEEK. A PERIOD OF OFFSHORE IS ALSO POSSIBLE THURSDAY INTO FRIDAY BASED ON THE LATEST MODEL TRENDS.

&&

.AVIATION... CLEAR SKIES AND UNRESTRICTED VISIBILITIES TODAY AND TONIGHT. STRONG NORTHERLY WINDS ALOFT THIS MORNING...AND LOCALLY STRONG GUSTY NORTH TO NORTHEAST OFFSHORE SURFACE WINDS WILL AFFECT PORTIONS OF THE AREA ESPECIALLY BELOW PASSES AND CANYONS. THESE WINDS WILL CREATE SOME SEVERE TURBULENCE NEAR AND DOWNWIND OF THE MOUNTAINS...ALONG WITH LOW LEVEL WIND SHEAR. WINDS WILL GRADUALLY DECREASE AFTER 18Z THROUGH THIS EVE. WINDS AT 10 KFT NORTH 30-40 KT AT DAYBREAK...DECREASING TO 20-25 KT THIS AFTN.

&&

.MARINE... LARGE NORTHWEST SWELL IN THE COASTAL WATERS PEAKED ON FRI EVE AND WILL GRADUALLY DECREASE THROUGH TONIGHT. EXPECT CONTINUED HIGH SURF ADVISORY CONDITIONS ALONG THE SAN DIEGO COUNTY COAST TODAY BUT WITH STEADY DECREASES THROUGH EARLY SUNDAY.

&&

.SGX WATCHES/WARNINGS/ADVISORIES... CA...WIND ADVISORY UNTIL 2 PM PST THIS AFTERNOON FOR ORANGE COUNTY COASTAL AREAS-RIVERSIDE COUNTY MOUNTAINS-SAN BERNARDINO COUNTY MOUNTAINS-SAN DIEGO COUNTY MOUNTAINS.

HIGH WIND WARNING UNTIL 2 PM PST THIS AFTERNOON FOR SAN BERNARDINO AND RIVERSIDE COUNTY VALLEYS-THE INLAND EMPIRE- SANTA ANA MOUNTAINS AND FOOTHILLS.

HIGH SURF ADVISORY UNTIL 7 AM PST SUNDAY FOR SAN DIEGO COUNTY COASTAL AREAS.

PT...NONE.

&&

$$

PUBLIC...MARTIN AVIATION/MARINE...LAVIS

NWS ON THE WEB AT WEATHER.GOV/SANDIEGO

.UPDATE...UPDATE TO UPGRADE THE WIND ADVISORY FOR THE INLAND EMPIRE AND THE SANTA ANA MOUNTAINS AND FOOTHILLS TO A HIGH WIND WARNING THROUGH EARLY AFTERNOON SATURDAY.

&&

.SYNOPSIS... SURFACE HIGH PRESSURE BUILDING OVER NEVADA COUPLED WITH STRONG NORTHEAST WINDS ALOFT WILL BRING GUSTY SANTA ANA WINDS THROUGH THE PASSES AND CANYONS THROUGH SATURDAY AFTERNOON. LIGHTER WINDS WILL PREVAIL THROUGH THE REST OF THE HOLIDAY WEEKEND ALONG WITH WARM DAYS AND COOL NIGHTS. THE NEXT CHANCE FOR RAIN WILL ARRIVE TUESDAY NIGHT AND WEDNESDAY AS A TROUGH OF LOW PRESSURE APPROACHES FROM THE WEST.

&&

.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES...

UPDATE TO UPGRADE THE WIND ADVISORY FOR THE INLAND EMPIRE AND THE SANTA ANA MOUNTAINS AND FOOTHILLS TO A HIGH WIND WARNING THROUGH EARLY AFTERNOON SATURDAY. RECENT ACARS SOUNDINGS FROM ONTARIO SHOW A VERY IMPRESSIVE SUBSIDENCE INVERSION NEAR 700 MB FAVORABLE FOR MOUNTAIN WAVE DEVELOPMENT AS WELL AS AN OVERALL STRONG WIND FIELD BELOW 700 MB WITH WINDS UP TO 50 KNOTS OR SO. WINDS IN THE WINDIER LOCATIONS...BELOW THE CAJON PASS AND NEAR FREMONT CANYON HAVE GUSTED TO AROUND 60 MPH IN THE PAST HOUR. NAM SHOWS STRONGEST SUPPORT FOR WINDS THROUGH 12Z...THEN GRADUALLY DECREASING SATURDAY MORNING THROUGH EARLY AFTERNOON. CONDITIONS ARE FAVORABLE FOR DAMAGING WINDS IN THE WINDIER LOCATIONS FOR TONIGHT THROUGH MID MORNING SATURDAY. UPDATES WILL BE OUT IN THE NEXT 30 MINUTES

&&

.PREV DISCUSSION... /ISSUED 930 PM PST FRI DEC 22 2006/

THE WIND PROFILE ON THE 00Z NKX SOUNDING WAS UNIQUE THIS EVENING...SHOWING NORTH WINDS EXTENDING FROM THE SURFACE ALL THE WAY TO 300 MB. IT SHOWED JUST HOW POWERFUL THE JET IS ON THE BACKSIDE OF THE DEPARTING UPPER LOW OVER SW AZ WITH 100 KT WINDS AT 500 MB. THE WIND TRAJECTORIES SHIFT EVER SO SLOWLY FROM THE NORTH TO THE NORTHEAST OVERNIGHT...COMBINING FORCES WITH A 1037 MB SURFACE HIGH BUILDING OVER THE GREAT BASIN BY 12Z SAT...AND ADDING TO THE STRENGTH OF THE OFFSHORE WINDS. THE PRESSURE GRADIENTS CONTINUE TO ACCELERATE OFFSHORE THIS EVENING AND WERE 9MB FROM SAN-TPH AT 05Z.

THE LATEST WRF AND NAM MODELS WERE A LITTLE STRONGER THAN PREVIOUS RUNS WITH THIS EVENT AND SHOW THE 850 MB WINDS RAMPING AND PEAKING AT 50 KTS BTWN 06-12Z OVER THE SAN BERNARDINOS. THIS WILL END UP AS A HIGH END WIND ADVISORY...LOW END HIGH WIND WARNING EVENT (GUSTS OF 58 MPH OR MORE)...WHICH COULD BRIEFLY BE EXCEEDED IN THE WIND PRONE AREAS OF THE SANTA ANA MTN AND THROUGH THE CAJON PASS.

THE STRONGEST DOWNWARD FORCING AND CAA OCCURS OVER LA AND SAN BERNARDINO COUNTIES WHICH IS WHERE THE STRONGEST WINDS WILL LIKELY SURFACE. WEAKER FORCING FARTHER SOUTH OVER RIV AND SAN DIEGO COUNTIES WILL BE OFFSET BY 850 MB WINDS THAT PEAK NEAR 40-45 KTS AFT 06Z...SO IT SEEMS LIKELY THAT GUSTY WINDS WILL OCCUR THROUGH THOSE PASSES TONIGHT AND SATURDAY AS WELL. I-8 THROUGH THE SAN DIEGO MTNS WILL BE PARTICULARLY SUSCEPTIBLE AS THE FLOW ALOFT TURNS MORE NORTHEAST SATURDAY MORNING.

SATURDAY AFTERNOON THE UPPER WIND SUPPORT AND THERMAL GRADIENTS WEAKEN AND THE WINDS WILL DIMINISH THROUGH THE EVENING. ON SUNDAY OUR WEATHER WILL BE DOMINATED BY HIGH PRESSURE...BOTH SURFACE AND ALOFT...FOR DRY WEATHER AND SEASONAL TEMPS. HIGH CLOUDS WILL SPILL OVER THE TOP THE WEAKENING RIDGE CHRISTMAS DAY BUT HAVE LITTLE EFFECT ON THE TEMPS WHERE HIGHS WILL BE AT OR ABOVE NORMAL ALL AREAS.

...FROM PREVIOUS DISCUSSION...

.LONG TERM (TUESDAY THROUGH THURSDAY)...THE GFS MODEL SHOWS THE RIDGE FLATTENING WITH ANOTHER WEAK SHORT-WAVE TROUGH FORECAST TO SNEAK BY ON WED MORNING. THE MODEL GENERATES SOME PRECIPITATION... SO IT LOOKS LIKE IN THE TUE NIGHT TO WED TIME FRAME THERE IS A CHANCE OF ANOTHER SHOT OF LIGHT PRECIPITATION. WEAK HIGH PRESSURE IS FORECAST TO BUILD RIGHT BACK IN WITH DRY AND MILD WEATHER INTO THE NEW YEAR.

&&

.AVIATION... CLEAR SKIES EXPECTED THROUGH SAT. SURFACE FLOW GOING OFFSHORE WITH STRONG NORTH WINDS ALOFT. GUSTY NORTH WINDS OVER THE MOUNTAINS WILL CREATE SOME SEVERE TURBULENCE AND LLWS. GUSTY NORTHEAST WINDS ARE EXPECTED LATE TONIGHT THROUGH SAT MORNING BELOW PASSES AND CANYONS INLAND TO THE COAST OF ORANGE COUNTY TO NORTHERN SAN DIEGO COUNTY COAST. WINDS AT 5K FT...NORTH 20-30 KT...BECOMING NORTH 5-15 KT BY SAT AFTERNOON... THEN NORTHWEST 10-20 SAT NIGHT. WINDS AT 10K FT...NORTH 40-50 KT... BECOMING NORTH 15-20 KT SAT AFTERNOON...THEN NORTHWEST 20-35 KT SAT NIGHT.

&&

.MARINE... LARGE NORTHWEST SWELL MAINLY PASSING THROUGH THE OUTER WATERS WILL RAPIDLY DECREASE SATURDAY WITH SOME SMALL OCCASIONAL INCREASES FOR NEXT WEEK.

&&

&&

.SGX WATCHES/WARNINGS/ADVISORIES... CA...WIND ADVISORY UNTIL 2 PM PST SATURDAY FOR ORANGE COUNTY COASTAL AREAS-RIVERSIDE COUNTY MOUNTAINS-SAN BERNARDINO COUNTY MOUNTAINS-SAN DIEGO COUNTY MOUNTAINS.

HIGH WIND WARNING UNTIL 2 PM PST SATURDAY FOR SAN BERNARDINO AND RIVERSIDE COUNTY VALLEYS-THE INLAND EMPIRE-SANTA ANA MOUNTAINS AND FOOTHILLS.

HIGH SURF ADVISORY UNTIL 7 AM PST SUNDAY FOR SAN DIEGO COUNTY COASTAL AREAS.

PT...NONE.

&&

$$

PUBLIC...MOEDE/MARTIN AVIATION/MARINE...WHITLOW

NWS ON THE WEB AT WEATHER.GOV/SANDIEGO

.DISCUSSION FOR EARLY MORNING ZONES/GRIDS... 300 AM CST

LARGE CYCLONE OF PAST 24HRS EXITING INTO ONTARIO THIS MORNING WITH WRAP AROUND CLOUDS PERSISTING AT LEAST FOR A WHILE. ANY PRECIP SHOULD STAY IN WISC THIS MORNING. EXPECT CLEARING FROM W AND SW THIS AFTERNOON. REMAINDER OF WEEKEND EXPECTED TO BE QUIET AND COOL.

RATHER ACTIVE HEMIS PATTERN CONTINUES WITH ANOTHER VIGOROUS TROUGH NOW WORKING ACROSS NRN OLD MEXICO EXPECTED TO MOVE INTO WESTERN GULF ON SUNDAY. VERY STRONG SHORT WAVE COMING ASHORE ON OREGON COAST THIS MORNING FCST TO MOVE ACROSS THE NORTHERN ROCKIES NEXT 24HRS THEN AMPLIFY INTO PLAINS LATER SUNDAY. THIS SETS THE STAGE FOR MAJOR CYCLOGENESIS AS TWO SYSTEMS PHASE ALONG THE MISS RIVER. WHILE OVERALL SCENARIO IS FAIRLY CLEAR THE DETAILS IN THIS PHASING WILL DETERMINING THREAT FOR SNOW IN FCST AREA LATER CHRISTMAS DAY INTO TUE MORNING. OF ALL MODELS GFS IS FURTHEST WEST WITH DEVELOPING LOW..TRACKING CENTER INTO NW OHIO TUE MORNING. GIVEN STRENGTH OF SYSTEM THIS WOULD PUT MOST OF AREA IN SNOW WITH HEAVIEST OVER NW INDIANA AND EASTWARD. GFS ALSO FORMS CLOSED UPPER CIRCULATION OVER WESTERN TENN MON EVENING WHICH ACCOUNTS FOR THE WESTWARD DISPLACEMENT OF SFC LOW...OCCLUSION PROCESS. WRF AND ECMWF MAINTAIN AN OPEN YET DEEP MID LEVEL TROUGH WHICH FORCES THE SURFACE LOW EASTWARD TOWARD THE COAST OR ALONG THE APPALACHIANS. IN EITHER CASE THERE IS ALWAYS THE THREAT OF A COASTAL LOW DEVELOPMENT ALONG THE MID ATLANTIC WHICH WOULD DRAG THE BETTER PRECIP EASTWARD BY EARLY TUESDAY.

THE DETAILS IN HOW THIS PHASING PLAYS OUT WILL DETERMINE ANY THREAT OF SNOW TO FCST AREA LATE MON INTO TUE. CURRENT GOING FCST HAS A CHC OF SNOW AND THAT WILL BE CONTINUED ALTHOUGH POPS WILL BE RAISED A TAD. IN ANY EVENT IT APPEARS THE CYCLONE WILL SWING OFF TO THE EAST DURING THE DAY TUESDAY WITH MORE ZONAL FLOW THE REMAINDER OF THE WEEK ALONG WITH NEAR SEASONAL TEMPS. KL

&&

.AVIATION DISCUSSION FOR 18Z TAFS... 1210 PM CST

MAIN AVIATION CHALLENGE TODAY WILL BE TIMING ENDING OF MVFR/IFR CIGS AT TERMINALS AND WINDS.

SURFACE LOW CONTINUES TO PULL OFF TO THE NORTHEAST ACROSS SOUTHEAST ONTARIO LATE THIS MORNING WITH GUSTY WESTERLY WINDS PERSISTING ACROSS NORTHERN ILLINOIS AND NORTHWEST INDIANA. ACARS SOUNDINGS INDICATING A RATHER SHARP LOW LEVEL INVERSION BASED ABOVE THIS MIXED LAYER AT AROUND 2500-3000 FT. BACK EDGE OF THIS IFR/MVFR LOW CLOUD DECK EXTENDS FROM DBQ TO SQI TO NEAR PIA AT 18Z. CURRENT SATELLITE VISIBLE IMAGERY TRENDS WOULD SUGGEST THAT THESE LOW CLOUDS WILL SHIFT EAST OF ROCKFORD IN THE 21Z-22Z TIME FRAME...AND EXITING EASTERN TERMINALS CLOSER TO 23Z. HOWEVER...MAY NOT BE OUT OF THE WOODS IN TERMS OF LOW CLOUD CIGS BY THIS TIME. OVER PAST FEW HOURS...HAVE SEEN INCREASE IN MVFR/IFR CLOUDS ACROSS SERN MINNESOTA/NERN IOWA. THIS APPEARS TO BE IN CLOSE PROXIMITY TO A WEAK SURFACE BOUNDARY/WEAK LOW LEVEL CONVERGENCE IN ASSOCIATION WITH AN UPPER LEVEL SHORT WAVE WORKING ACROSS THE EASTERN DAKOTAS AT THIS TIME. CONCERN IS THAT LOW CLOUDS WILL CONTINUE TO REFORM THROUGH THE AFTERNOON NEAR THIS BOUNDARY GIVEN TRAPPED LOW LEVEL MOISTURE WITH THE STRONG INVERSION PREVIOUSLY NOTED. THUS...BY 22-23Z WILL TREND TO PREVAILING SCATTERED LOW END MVFR DECK ~ 1K FT WITH MENTION BKN-OVC CONDITIONS POSSIBLY AFFECTING TERMINALS AGAIN THROUGH 03Z. AFTER THIS TIME...SKIES SHOULD CLEAR WITH PERHAPS JUST A FEW CIRRUS OVERNIGHT.

WEST WINDS GUSTING TO 20 TO 25 KNOTS THIS AFTERNOON WILL DIMINISH TOWARD EVENING AS SFC GRADIENT WEAKENS...WITH WINDS BECOMING LIGHT WESTERLY OVERNIGHT...AND THEN SOUTHWEST AT AROUND 10 KNOTS BY THE END OF THE FORECAST PERIOD AS ANOTHER SFC TROUGH MOVES INTO THE UPPER MIDWEST SUNDAY AFTERNOON.

MARSILI

&&

.LOT WATCHES/WARNINGS/ADVISORIES... .IL...NONE. .IN...NONE. .LM...GALE WARNING OPEN WATERS THRU 20Z TODAY. SMALL CRAFT ADVISORY WINTHROP HARBOR TO GARY THROUGH 3 PM CST THIS AFTERNOON. SMALL CRAFT ADVISORY GARY TO MICHIGAN CITY THROUGH 8 PM CST THIS EVENING.

&&

$$

.SHORT TERM /TONIGHT THROUGH SUNDAY/... WATER VAPOR LOOP SHOWS AN UPPER LOW LIFTING THROUGH THE UPPER GREAT LAKES. A DUAL STREAM SYSTEM IS MOVING INTO THE ROCKIES (NORTHERN STREAM WAVE NEAR LAKE WINNIPEG...SOUTHERN STREAM WAVE ACROSS NORTHERN MEXICO). ACARS 400-250MB WIND OBSERVATIONS REVEAL A 120-150KT JET FROM THE CENTRAL GULF STATES NORTHEAST INTO NEW ENGLAND. 12Z SURFACE ANALYSIS PLACED A 997MB OCCLUDED CYCLONE ACROSS THE NORTHERN GREAT LAKES...WITH THE OCCLUDED BOUNDARY EXTENDED SOUTHEAST THROUGH PENNSYLVANIA TOWARD CHARLOTTESVILLE...WHERE IT BECAME A COLD FRONT THROUGH THE CENTRAL GULF OF MEXICO. A WARM FRONT EXTENDED FROM NEAR CHARLOTTESVILLE NORTHEAST TO SOUTH OF BOSTON.

THIS EVENING WILL FEATURE CLEAR SKIES AS WINDS DECOUPLE. THERE MAY BE STRATUS ASSOCIATED WITH THE ARRIVAL OF THE NEXT NORTHERN STREAM WAVE LATE TONIGHT...PARTICULARLY ACROSS THE MOUNTAINS AND ALONG THE PENNSYLVANIA BORDER. THE COLDEST RURAL LOCATIONS MAY GET INTO THE LOWER 30S AS DEWPOINTS CONTINUE TO FALL WITH POST FRONTAL DOWNSLOPE FLOW.

EXPECT SKY TO CLEAR MIDDAY SUNDAY AS CLOUDINESS DIMINISHES WITH THE PASSAGE OF THE WAVE. THIS SHOULD TIGHTEN THE PRESSURE GRADIENT AND SUPPLY SLIGHTLY BREEZIER CONDITION COMPARED TO TODAY. TEMPERATURES WILL BE COOLER (ALBEIT STILL WELL ABOVE NORMAL)...WITH CONTINUED COOL ADVECTION.

&&

.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... VERY COMPLEX WX TO PLAY OUT ACROSS THE MID ATLC THROUGHOUT THE LONG TERM.

SUNDAY NIGHT APPEARS TO BE THE QUIETEST OF THE NEXT SEVERAL. COMPLEX SFC LOW OVER THE NW GULFMEX BY THE BEGINNING OF THE PERIOD WILL BE THE MAIN WX MAKER THROUGH MID WEEK. CLDS ON THE INCREASE TOWARD XMAS MORNING. 06Z AND 12Z GFS INTROCUDE PCPN INTO FAR SW ZONES BY DAYBREAK...BUT PRIND THAT THIS MAY BE TOO EARLY AS THE GFS IS THE FASTEST OF THE UKMET/ECMWF/SREF MEAN. WL KEEP THINGS DRY FOR SUN NIGHT AND INTRODUCE PCPN EARLY IN THE MORNING MONDAY WITH THE MAIN FOCUS OF THE PCPN TO AFFECT THE ENTIRE CWFA DURING THE DAY MON AND MONDAY NIGHT.

WILL RAMP POPS QUICKLY UP TO CATEGORICAL DURING THE DAY MONDAY CONTINUING INTO THE EVENING HOURS. SREFS SUGGEST A VERY HIGH PROBABILITY OF AT LEAST A 1 INCH QPF EVENT MONDAY AND THIS GOES WELL WITH CURRENT THINKING OF A 1 TO MAYBE 1.5 INCH AEREAL QPF EVENT.

PTYPE REMAINS IN QUESTION AT THE ONSET OF PCPN ESPECICALLY OVER THE HIGHER TERRAIN OF THE WESTERN 1/3 OF THE CWFA. HAVE INTRODUCED CHC -FZRA/IP ABOVE 2KFT FOR THE FIRST FEW HRS OF THE EVENT MONDAY AS FCST SOUNDINGS SUGGEST THAT BEFORE THE SIGNIFICANT WARMING IN THE H9-H8 LAYER TAKES PLACE WET BULB PROCESSES COULD LEAD TO A FEW HRS OF FZRA WITH TEMPS IN THE 30-32F RANGE. ALL INDICATIONS SUGGEST THAT THIS WILL NOT CONTINUE FOR A LONG TIME AS STRONG WARMING OCCURS IN THE LAYER.

COMPLEX SFC LOW EVOLUTION OCCURS DURING THE DAY MON AS IT TRAVELS NORTH. GFS AND SREF ENSEMBLE MEMBERS STILL UNDECIDED WHAT...IF ANY SECONDARY CYCLOGENESIS IS LIKELY TO OCCUR NEAR THE MID ATLC AS THE PRIMARY LOW TRAVELS INTO WRN PA. IF THERE HAD BEEN MORE COLD AIR DAMMED UP EAST OF THE MTNS WOULD BE MUCH MORE CONFIDENT IN A STRONGER SECONDARY LOW NEAR THE TRIPLE POINT ON/NEAR THE ATLC SHORELINE. HOWEVER THE LACK OF POLAR AIR SHOULD ALLOW THINGS TO REMAIN ONSHORE AND WEAKER WITHOUT THE BOTTOM FALLING OUT OF THE SECONDARY LOW.

ALL IN ALL...OCCLUDED BOUNDARY LIFTS NORTH AND EAST OF THE AREA LATE MON NIGHT/TUE WITH COLD ADVECTION TAKING OFF. THE NEXT SET OF WX PROBLEMS TO BEGIN TUE AS SFC LOW BOTTOMS OUT OVER NORTHERN NEW ENGLAND.

UPSLOPE SNOW SHOWERS TO BEGIN WITH A VENGANCE IN THE POTOMAC HIGHLANDS LATE MONDAY NIGHT AND CONTINUING AT LEAST UNTIL WED. SREF PLUMES SHOWING AT LEAST 0.75 IN OF QPF FALLING IN THE FORM OF SN. PTYPE NOT AN ISSUE THIS TIME AS COLD AIR WILL QUICKLY CHANGE ANY LEFTOVER RA TO SN BY EARLY TUE. THIS LOOKS TO BE A PROLONGED EVENT IN DURATION WITH RESPECTABLE QPF. STILL TOO EARLY FOR A WINTER STORM WATCH AT THIS POINT BUT WL HAVE TO CONSIDER THIS IN LATER SHIFTS.

THE SYNOPTIC CLIMATOLOGY OF THIS SURFACE LOW STRENGTH AND TRACK SUGGESTS A STRONG/HIGH WIND EVENT IS POSSIBLE ACROSS TEH CWFA DURING THE DAY TUE AND WILL MAINTAIN MENTION OF GALE FORCE WINDS OVER THE WATER. WIND GUSTS TO AROUND 40KT TUE...DEPENDING ON HOW MUCH INSOLATION WE`RE ABLE TO REALIZE. CLOUD COVER WILL BE ROBUST TUES WITH THE STRONG UPR TROF OVERHEAD LIFTING NORTHEAST.

A FEW QUIET DAYS IN STORE FOR THE END OF THE UPCOMING WORK WEEK BEFORE NEXT SYS APCHS BY THE WKND. SIGNIFICANT DISAGREEMENT AS TO HOW THIS NEXT SYSTEM IS PLAYING OUT WITH TIMING AND STRENGTH DIFFERENCES ABOUNDING IN THE MEDIUM RANGE GUIDANCE SUITE. FOLLOWING HPC SOLN WITH MIXED PCPN INTRODUCED FOR FRIDAY NIGHT IN THE SHEN VALLEY AND ALG THE BLUE RIDGE.

&&

.HYDROLOGY... 12Z MPE DATA INCORPORATING PRECIPITATION ESTIMATES FROM REGIONAL DOPPLER RADARS AND RAIN GAGES...VERIFIES CLOSE TO AN INCH OF RAIN FELL ACROSS MANY LOCATIONS. THIS SHOULD CAUSE ONLY A GRADUAL RISE ACROSS CREEKS AND STREAMS...LEADING INTO THE MAIN RIVER STEMS THROUGH THE WEEKEND.

&&

.AVIATION /20Z-18Z/... WIND GUSTS DIMINISH DIURNALLY. COULD SEE SOME STRATUS WITH THE NEXT WAVE LATE TONIGHT INTO EARLY SUNDAY MORNING. WINDS GUST AGAIN WITH MIXING SUNDAY.

&&

.MARINE... A SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR THE TIDAL POTOMAC RIVER NORTH OF INDIAN HEAD...AND THE CHESAPEAKE BAY NORTH OF NORTH BEACH THROUGH 6 PM...FOR WIND GUSTS OF 20-25 KNOTS.

RAISED A SMALL CRAFT ADVISORY ALONG THE TIDAL POTOMAC RIVER AND MARYLAND CHESAPEAKE BAY SUNDAY MORNING INTO THE AFTERNOON. WIND GUSTS OF 20-25 KT SUPPORTED BY PROXIMITY 12Z GFS/NAM BUFKIT FORECAST SOUNDINGS...IN ADDITION TO MARINE BUFKIT SOUNDINGS FROM THE 6KM LWX WRF-NMM AS THE GRADIENT TIGHTENS BEHIND THE PASSAGE OF A MID LEVEL WAVE.

TUE WIND FORECAST IS DEFINITELY TRICKY. THE EXTENT OF CLOUD COVER IS GOING TO BE THE BIG PLAYER. PLENTY OF MOMENTUM ALOFT TO TRANSPORT DOWN AND GOOD ISOALLOBARIC CONTRIBUTION AS SURFACE LOW RAPIDLY DEEPENS OVER NEW ENGLAND. GALE FORCE WIND GUSTS LOOK TO BE A GOOD BET DURING THE DAY TUES...BUT THIS WILL...TO SOME EXTENT DEPEND ON THE AMOUNT OF CLOUD COVER LEFT OVER WITH THE UPR TROF STILL LINGERING OVERHEAD WITH CYCLONIC FLOW.

&&

.TIDES... WATER LEVELS ARE CURRENTLY A HALF FOOT TO A FOOT ABOVE ASTRONOMIC PREDICTIONS...BUT ARE WELL BELOW THRESHOLD CRITERIA FOR MINOR COASTAL FLOODING. THE LUNAR PHASE IS WAXING FROM A NEW MOON (12% FULL). INCREASING WESTERLY FLOW SHOULD ALLOW TIDES TO CONTINUE TO RETURN TO ASTRONOMIC PREDICTIONS TONIGHT.

WATER LEVELS MAY INCREASE SLIGHTLY ABOVE PREDICTED VALUES LATE MONDAY AND EARLY TUESDAY BEFORE STRONG WEST WINDS TAKE OFF DURING THE DAY TUE. EXPECT WATER LEVELS TO GO BELOW ASTRONOMICAL PREDICTED LEVELS TUE AND TUE NIGHT...ESPECIALLY ALONG THE WESTERN SHORE OF THE CHESAPEAKE BAY AS STRONG WEST WINDS BECOME THE PREDOMINANT FACTOR.

&&

.LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS AFTERNOON FOR ANZ530>532-535.

SMALL CRAFT ADVISORY FROM 8 AM TO 4 PM EST SUNDAY FOR ANZ530>537.

&&

$$

SHORT TERM/HYDROLOGY/AVIATION...ROGOWSKI LONG TERM...MANNING MARINE/TIDES...MANNING/ROGOWSKI

.MARINE UPDATE... ADDED THE TIDAL POTOMAC RIVER TO THE SMALL CRAFT ADVISORY FROM WASHINGTON DC SOUTH TO INDIAN HEAD. WIND GUST OF 21KT WAS RECORDED AT KDCA AT 1652Z...AND EXPECT THIS AREA TO SEE SIMILAR WINDS THROUGH THE AFTERNOON. ALSO REMOVED EARLIER WIND WORDING FROM SEVERAL OTHER GROUPS.

&&

.SHORT TERM... WATER VAPOR LOOP SHOWS AN UPPER LOW LIFTING THROUGH THE UPPER GREAT LAKES. A DUAL STREAM SYSTEM IS MOVING INTO THE ROCKIES (NORTHERN STREAM WAVE NEAR LAKE WINNIPEG...SOUTHERN STREAM WAVE ACROSS NORTHERN MEXICO). ACARS 400-250MB WIND OBSERVATIONS REVEAL A 120-150KT JET FROM THE CENTRAL GULF STATES NORTHEAST INTO NEW ENGLAND. 12Z SURFACE ANALYSIS PLACED A 997MB OCCLUDED CYCLONE ACROSS THE NORTHERN GREAT LAKES...WITH THE OCCLUDED BOUNDARY EXTENDED SOUTHEAST THROUGH PENNSYLVANIA TOWARD CHARLOTTESVILLE...WHERE IT BECAME A COLD FRONT THROUGH THE CENTRAL GULF OF MEXICO. A WARM FRONT EXTENDED FROM NEAR CHARLOTTESVILLE NORTHEAST TO SOUTH OF BOSTON.

FOG WILL CONTINUE TO DISSIPATE DURING THE MID MORNING. VISIBILITIES WERE NEAR ZERO AT MANY LOCATIONS...BUT FOG WOULD HAVE BEEN MORE WIDESPREAD/PERSISTENT IF MID LEVEL CLOUDS WOULD HAVE MOVED OFF TO THE EAST AS FORECAST YESTERDAY. THIS WILL OCCUR THROUGH MIDDAY AS THE SOUTHWESTERLY UPPER LEVEL JET AXIS SHIFTS EAST FROM THE APPALACHIANS TOWARD THE EAST COAST. THE SKY WILL CLEAR FOR SUNNY CONDITIONS THIS AFTERNOON AS A RESULT.

THE PASSAGE OF THE OCCLUDED BOUNDARY THIS MORNING WILL PROMOTE WESTERLY DOWNSLOPE FLOW. IN ADDITION TO AIDING THE SCOURING OUT OF LOW LEVEL MOISTURE...THIS WILL HELP PROMOTE MIXING OF +12C 925MB TEMPERATURES (AS OBSERVED ON 12Z KIAD RAOB AND MORNING ACARS SOUNDINGS) TO THE SURFACE. THUS...WENT ABOVE MOS GUIDANCE CLOSER TO THE MID TO UPPER 60S (ACCOUNTING FOR A COOLING WARM LAYER ABOVE THE SURFACE THROUGH THE AFTERNOON).

&&

.HYDROLOGY... 12Z MPE DATA INCORPORATING PRECIPITATION ESTIMATES FROM REGIONAL DOPPLER RADARS AND RAIN GAGES...VERIFIES CLOSE TO AN INCH OF RAIN FELL ACROSS MANY LOCATIONS. THIS SHOULD CAUSE ONLY A GRADUAL RISE ACROSS CREEKS AND STREAMS...LEADING INTO THE MAIN RIVER STEMS THROUGH THE WEEKEND. A FEW FORECAST POINTS MAY RISE ENOUGH TO BE UNSAFE FOR RECREATIONAL USE LATE THIS WEEKEND.

&&

.AVIATION... AREAS OF FOG WILL CONTINUE TO BURN OFF...AND WITH THE PASSING OF MID LEVEL CLOUDS SKIES WILL BE CLEARING. WESTERLY WINDS WILL STRENGTHEN WITH MIXING POST FRONTAL FLOW.

&&

.MARINE... THE APPROACH OF THE OCCLUDED BOUNDARY HAS CEASED PREFRONTAL SMALL CRAFT WINDS.

RAISED A SMALL CRAFT NORTH OF NORTH BEACH THIS AFTERNOON WITH POST FRONTAL WIND GUSTS OF 20-25 KT SUPPORTED BY PROXIMITY 06Z GFS/NAM BUFKIT FORECAST SOUNDINGS...IN ADDITION TO MARINE BUFKIT SOUNDINGS FROM THE 6KM LWX WRF-NMM.

&&

.TIDES... WATER LEVELS ARE CURRENTLY A FOOT ABOVE ASTRONOMIC PREDICTIONS...BUT ARE WELL BELOW THRESHOLD CRITERIA FOR MINOR COASTAL FLOODING. THE LUNAR PHASE IS WAXING FROM A NEW MOON (10% FULL). INCREASING WESTERLY FLOW THIS AFTERNOON SHOULD ALLOW TIDES TO RETURN TO ASTRONOMIC PREDICTIONS.

&&

.LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS AFTERNOON FOR ANZ530>532-535.

&&

$$

SHORT TERM/HYDROLOGY/AVIATION/MARINE/TIDES...ROGOWSKI

.SHORT TERM... WATER VAPOR LOOP SHOWS AN UPPER LOW LIFTING THROUGH THE UPPER GREAT LAKES. A DUAL STREAM SYSTEM IS MOVING INTO THE ROCKIES (NORTHERN STREAM WAVE NEAR LAKE WINNIPEG...SOUTHERN STREAM WAVE ACROSS NORTHERN MEXICO). ACARS 400-250MB WIND OBSERVATIONS REVEAL A 120-150KT JET FROM THE CENTRAL GULF STATES NORTHEAST INTO NEW ENGLAND. 12Z SURFACE ANALYSIS PLACED A 997MB OCCLUDED CYCLONE ACROSS THE NORTHERN GREAT LAKES...WITH THE OCCLUDED BOUNDARY EXTENDED SOUTHEAST THROUGH PENNSYLVANIA TOWARD CHARLOTTESVILLE...WHERE IT BECAME A COLD FRONT THROUGH THE CENTRAL GULF OF MEXICO. A WARM FRONT EXTENDED FROM NEAR CHARLOTTESVILLE NORTHEAST TO SOUTH OF BOSTON.

FOG WILL CONTINUE TO DISSIPATE DURING THE MID MORNING. VISIBILITIES WERE NEAR ZERO AT MANY LOCATIONS...BUT FOG WOULD HAVE BEEN MORE WIDESPREAD/PERSISTENT IF MID LEVEL CLOUDS WOULD HAVE MOVED OFF TO THE EAST AS FORECAST YESTERDAY. THIS WILL OCCUR THROUGH MIDDAY AS THE SOUTHWESTERLY UPPER LEVEL JET AXIS SHIFTS EAST FROM THE APPALACHIANS TOWARD THE EAST COAST. THE SKY WILL CLEAR FOR SUNNY CONDITIONS THIS AFTERNOON AS A RESULT.

THE PASSAGE OF THE OCCLUDED BOUNDARY THIS MORNING WILL PROMOTE WESTERLY DOWNSLOPE FLOW. IN ADDITION TO AIDING THE SCOURING OUT OF LOW LEVEL MOISTURE...THIS WILL HELP PROMOTE MIXING OF +12C 925MB TEMPERATURES (AS OBSERVED ON 12Z KIAD RAOB AND MORNING ACARS SOUNDINGS) TO THE SURFACE. THUS...WENT ABOVE MOS GUIDANCE CLOSER TO THE MID TO UPPER 60S (ACCOUNTING FOR A COOLING WARM LAYER ABOVE THE SURFACE THROUGH THE AFTERNOON).

&&

.HYDROLOGY... 12Z MPE DATA INCORPORATING PRECIPITATION ESTIMATES FROM REGIONAL DOPPLER RADARS AND RAIN GAGES...VERIFIES CLOSE TO AN INCH OF RAIN FELL ACROSS MANY LOCATIONS. THIS SHOULD CAUSE ONLY A GRADUAL RISE ACROSS CREEKS AND STREAMS...LEADING INTO THE MAIN RIVER STEMS THROUGH THE WEEKEND. A FEW FORECAST POINTS MAY RISE ENOUGH TO BE UNSAFE FOR RECREATIONAL USE LATE THIS WEEKEND.

&&

.AVIATION... AREAS OF FOG WILL CONTINUE TO BURN OFF...AND WITH THE PASSING OF MID LEVEL CLOUDS SKIES WILL BE CLEARING. WESTERLY WINDS WILL STRENGTHEN WITH MIXING POST FRONTAL FLOW.

&&

.MARINE... THE APPROACH OF THE OCCLUDED BOUNDARY HAS CEASED PREFRONTAL SMALL CRAFT WINDS.

RAISED A SMALL CRAFT NORTH OF NORTH BEACH THIS AFTERNOON WITH POST FRONTAL WIND GUSTS OF 20-25 KT SUPPORTED BY PROXIMITY 06Z GFS/NAM BUFKIT FORECAST SOUNDINGS...IN ADDITION TO MARINE BUFKIT SOUNDINGS FROM THE 6KM LWX WRF-NMM.

&&

.TIDES... WATER LEVELS ARE CURRENTLY A FOOT ABOVE ASTRONOMIC PREDICTIONS...BUT ARE WELL BELOW THRESHOLD CRITERIA FOR MINOR COASTAL FLOODING. THE LUNAR PHASE IS WAXING FROM A NEW MOON (10% FULL). INCREASING WESTERLY FLOW THIS AFTERNOON SHOULD ALLOW TIDES TO RETURN TO ASTRONOMIC PREDICTIONS.

&&

.LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY FROM NOON TODAY TO 6 PM EST THIS AFTERNOON FOR ANZ530>532.

&&

$$

SHORT TERM/HYDROLOGY/AVIATION/MARINE/TIDES...ROGOWSKI

.DISCUSSION... 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW OCCLUDED LO THAT DUMPED UP TO A FOOT OF SNOW LAST NGT IN ONTONAGON AND GOGEBIC COUNTIES MOVING STEADILY ENEWD AND GIVING WAY TO SHRTWV RDGING OVER WRN LK SUP. VIGOROUS DNVA/H85-5 QVECTOR DVGC IN THE WAKE OF THIS SYS AS WELL AS VERY DRY AND RELATIVELY WARM LLVLS SHOWN ON THE 12Z INL RAOB/TAMDAR SDNG FM CYQT (H9 INVRN BASE TEMP THERE IS -3C COMPARED TO H86 INVRN BASE TEMP OF -6C AT RHI) HAVE CAUSED LINGERING SHSN OVER THE FA TO BCM SCT AND LGT. HAVE CUT POPS/DROPPED PREVIOUS HEADLINES WITH EXPECTATION STEADY MVMNT OF OCCLUSION TO THE NE AND ARRIVAL OF DRIER...WARMER AIR FM THE W WL CONTINUE TO DIMINISH ANY SHSN. ALSO BUMPED MAX TEMPS UP A COUPLE OF DEGREES ESPECIALLY OVER THE SCNTRL TO ACCOUNT FOR RELATIVELY WARM LLVL AIR AND DOWNSLOPE WARMING OF STRONG NW FLOW BTWN DEPARTING SFC LO AND HI PRES RDG IN THE PLAINS. GOING GALE WRNG ON LK SUP SEEMS ON TRACK WITH WIND GUSTS AT GRANITE ISLAND APRCHG 50 MPH AT TIMES AND 16Z SUSTAINED WIND AT STANNARD ROCK UP TO 38 KTS. CONCERNED STRONG WINDS MIGHT IMPACT THE ERN ZNS...BUT RELATIVELY HIER LLVL STABILITY OVER SHOULD PREVENT THOROUGH MIXING. DID MENTION WIND GUSTS UP TO 45 MPH NEAR THE SHORE E OF MQT IN THE ZFPMQT/GRIDS. PASSAGE OF PRES RISE MAX TO THE E BY EARLY THIS EVNG SHOULD DIMINISH GALES AS CURRENTLY FCST. OTRW...BAND OF MID AND HI CLD OVER MN IN ADVANCE OF ANOTHER SHRTWV MOVING ESE FM THE NRN PLAINS WL IMPACT THE FA LATER THIS AFTN...BUT LLVLS WL BE TOO DRY FOR PCPN.

KC

.PREVIOUS DISCUSSION (ISSUED AT 305 AM)... MAIN FORECAST CONCERN IS THE LINGERING PCPN ACROSS THE AREA...WITH MODERATE TO AT TIMES HEAVY SNOW OVER WESTERN UPPER MICHIGAN AND THE ONGOING TRANSITION FROM RAIN TO SNOW ACROSS THE EAST. LATEST WATER VAPOR IMAGERY AND LOCAL 20KM LAPS ANALYSES SHOW UPPER LOW ROTATING NE ACROSS THE EASTERN CWFA AT THIS TIME...WITH THE DRY SLOT/WARM TONGUE WRAPPED COMPLETELY AROUND THE CIRCULATION...WITH A WARM SECLUSION APPARENT IN THE WATER VAPOR IMAGERY AND SUBSTANTIATED BY THE 850-700MB THETA-E ANALYSES. THE MOST SIGNIFICANT PCPN AT THIS TIME IS ALONG AND NORTH AND WEST OF THIS TROWAL SIGNATURE...ON THE UPWARD SLOPING THETA-E SURFACES. GOOD DEFORMATION CAN BE SEEN IN THE WATER VAPOR IMAGERY AND THIS IS LEADING TO SOME DECENT MID-LEVEL FRONTOGENESIS...PARTICULARLY OVER WESTERN UPPER MICHIGAN...WHERE UPPER LEVEL DIVERGENCE AS SEEN ON THE 2PVU SURFACE FROM THE 00Z GFS IS ALSO HELPING THINGS OUT. THE 00Z MODEL GUIDANCE IS ALL IN GENERAL AGREEMENT THAT THE FORCING WILL CONTINUE TO IMPACT THE CWFA FOR ANOTHER 6 OR SO HOURS...THEN THINGS WILL QUICKLY FADE AS THE UPPER LOW PULLS OFF TO THE NORTHEAST.

SURFACE OBS CONTINUE TO SHOW FAIRLY WARM TEMPERATURES ALONG AND EAST OF THE SURFACE LOW TRACK...WITH RAIN GENERALLY ALONG AND EAST OF A LINE FROM MARQUETTE TO NORWAY. THE 00Z MODEL GUIDANCE VARIES A BIT ON THE LOW LEVEL THERMAL PROFILE OVER THE CWFA...AND BOTH THE NAM AND GFS SEEM A BIT TOO COOL OVER THE EASTERN CWFA WHERE THEY WOULD SUGGEST THAT THINGS SHOULD ALREADY BE TRANSITIONING TO SNOW. THE LOCAL 5KM WRF-ARW 925MB TEMPERATURE PROGS SEEM TO HAVE A DECENT HANDLE ON THE RAIN SNOW LINE...WITH THE 0-1C CONTOURS MATCHING UP WELL WITH WHERE THE CHANGEOVER IS OCCURRING. USING THAT AS A PROXY FOR THE RAIN/SNOW LINE SUGGESTS THAT THINGS WILL CONTINUE TO TRANSITION FROM RAIN TO SNOW FROM WEST TO EAST OVER THE NEXT 6 HOURS OR SO. EXPECT THIS TO OCCUR FROM MARQUETTE TO ESCANABA BY 10Z...FROM MUNISING TO MANISTIQUE AROUND 12Z...AND THROUGH NEWBERRY BY 15Z OR 16Z. OF COURSE...DURING THAT SAME TIME FRAME THE FORCING WILL BE WEAKENING ACROSS THE AREA AS THE MID-UPPER LEVEL DEFORMATION AXIS PULLS NORTHEAST.

ACTIVITY ACROSS THE AREA AT THIS TIME SHOWS SOME EMBEDDED CONVECTIVE ELEMENTS ON RADAR...AND CROSS SECTIONS ACROSS THE AREA THROUGH THE 00Z NAM AND GFS OUTPUT SHOW SOME NEGATIVE EPV PRESENT ALOFT. A CLOSER LOOK AT THETA-E VALUES SUGGESTS THIS IS MAINLY UPRIGHT INSTABILITY...ALTHOUGH SOME SYMMETRIC INSTABILITY IS ALSO PRESENT ACROSS THE AREA. REGARDLESS OF THE SOURCE...THIS IS HELPING TO BOOST OMEGA VALUES AND IS LEADING TO THE MORE NARROWLY FOCUSED BANDING OBSERVED IN THE PCPN RETURNS AT THIS TIME. THE INSTABILITY SHOULD WANE AS WE HEAD INTO THE MORNING HOURS AS THE MID LEVEL DRY SLOT MOVES AWAY AND THE PORTION LINGERING INTO OUR AREA WITH THE TROWAL MOISTENS UP. SO...WITH FORCING PULLING OFF AND INSTABILITY DECREASING THROUGH THE MORNING...EXPECT A FAIRLY RAPID DECREASE IN THE PCPN DURING THE MID MORNING HOURS. WE MAY HAVE SOME SNOW SHOWERS AND FLURRIES PERSIST INTO THE AFTERNOON WITH SOME DEEP LAYER MOISTURE LINGERING OVER THE AREA...BUT EXPECT THE ACCUMULATING SNOWFALL TO END DURING THE MORNING HOURS. WILL LEAVE THE CURRENT HEADLINE TIMING AS IS ALTHOUGH THE MORNING UPDATE SHIFT SHOULD BE ABLE TO END THE HEADLINES A BIT EARLIER.

THE SHORTWAVE TROUGH CURRENTLY SEEN IN THE WATER VAPOR IMAGERY FROM MANITOBA SOUTH INTO NORTHWEST NORTH DAKOTA WILL PUSH THROUGH THE AREA TONIGHT...BUT THERE SHOULD BE LITTLE IN THE WAY OF LOW LEVEL MOISTURE REMAINING OVER THE AREA BY THAT TIME...AND IT LOOKS LIKE IT WILL MAINLY JUST KEEP SOME MID LEVEL CLOUD COVER OVER THE AREA FOR THE FIRST PART OF THE NIGHT. OVER THE EASTERN COUNTIES WHERE SOME 925-850MB MOISTURE WILL BE LINGERING THIS SHORTWAVE COULD HELP KEEP SOME FLURRIES OR SNOW SHOWERS AROUND FOR PART OF THE NIGHT...SO WILL MAINTAIN SOME ACTIVITY IN THAT AREA FOR TONIGHT. BEHIND THIS FEATURE SUBSIDENCE BUILDS INTO THE AREA WITH A VENGEANCE...AND THE PROFILE DRIES SUBSTANTIALLY THROUGH ITS DEPTH. EXPECT SKIES TO CLEAR FROM WEEEST TO EAST LATER TONIGHT...WITH PLENTY OF SUNSHINE ON TAP FOR SUNDAY.

THE NEXT FEATURE OF INTEREST WILL MOVE TOWARD THE AREA ON MONDAY. THE VIGOROUS SHORTWAVE WHICH CAN CURRENTLY BE SEEN APPROACHING THE BRITISH COLUMBIA COAST WILL SKIRT AROUND THE TOP OF THE WESTERN RIDGE THEN BEGIN TO DIG SOUTHEAST ONCE IT GETS EAST OF THE ROCKIES. THIS FEATURE WILL WORK TO BRING A WEAK SURFACE WAVE AND COLD FRONT FROM SOUTH CENTRAL CANADA INTO OUR AREA ON MONDAY. THERE IS STILL A GOOD DEAL OF UNCERTAINTY REGARDING THIS FEATURE...SINCE THE NAM...GFS...UKMET...LOCAL 40KM WRF-ARW AND OTHER MODELS VARY ON THE DEGREE OF PHASING WITH THIS FEATURE AND THE SOUTHERN STREAM UPPER LOW CURRENTLY MAKING ITS WAY THROUGH FAR NORTHERN MEXICO. ALTHOUGH ALL OF THE SCENARIOS KEEP ANY EVENTUAL CYCLOGENESIS WELL TO OUR SOUTH AND EAST...THE DEGREE OF PHASING AND SUBSEQUENT DEVELOPMENT WILL HAVE AN IMPACT ON HOW LONG THE UPPER TROUGH AND DEEP MOISTURE LINGER OVER OUR AREA...AND HOW MUCH LOW LEVEL CYCLONIC FLOW IF ANY WILL BE PRESENT. SINCE IT APPEARS THAT BOUNDARY LAYER TEMPERATURES SHOULD BE SUFFICIENTLY COLD FOR LES MONDAY NIGHT INTO TUESDAY...THERE IS AT LEAST SOME POTENTIAL FOR DECENT LES IF DEEP MOISTURE AND CYCLONIC FLOW REMAIN OVER THE AREA ALONG WITH NORTHERLY BOUNDARY LAYER WINDS. BUMPED UP POPS A BIT TO ACCOUNT FOR THIS POSSIBILITY...AND THIS IS SOMETHING LATER SHIFTS WILL NEED TO MONITOR.

TRH

&&

.MQT WATCHES/WARNINGS/ADVISORIES...GALE WRNG LK SUP E 1/2. &&

$$

.DISCUSSION...

&&

.PREV DISCUSSION... /ISSUED 247 AM CST SAT DEC 23 2006/

DISCUSSION... UPPER LOW NORTH OF THE UPPER GRTLKS...IS EXPECTED TO LIFT NORTHEAST OVER EASTERN CANADA BY SUNDAY MRNG. THE LATEST NAM80 MODEL RUN...WAS HINTING AT MORE MOISTURE WITH THE NEXT SHORT WAVE TROUGH...FORECAST TO MOVE INTO THE NORTHERN PLAINS AND UPPER MIDWEST BY MONDAY MORNING. CURRENT THINKING IS TO THROW SOME SMALL POPS...STARTING LATE SUNDAY AFTERNOON OVER WEST CENTRAL AND CENTRAL MN.

NEXT SYSTEM TO APPROACH IN NW FLOW ON LATE SUN AFTN AND DURING THE NIGHT. 00Z GFS/UKMET ARE QUICKER WITH THIS SOLUTION AND NOT AS DEEP AND SOUTHWARD PROGRESSIVE AS THE 00Z NAM. LEAN TOWARDS THE GFS/UKMET WHICH OFFER SUFFICIENT HEIGHT FALLS AND OMEGA FOR CONTINUED LIGHT SNOW MENTION ON SUN NIGHT. CHRISTMAS DAY AS UPPER LOW PASSES OVER WILL BE A CHANCE OF SOME LINGERING FLURRIES UNDER LIKELY CLOUDS AND COLD AIR ADVECTION. TEMPS STILL ABOVE NORMAL WITH LACK OF ANY DECENT SNOW COVER.

MEDIUM RANGE...MODELS DIVERGE ON THE SOLUTION FOR THE LOW PRESSURE SYSTEM FORECAST TO LIFT INTO THE EASTERN CONUS ON TUESDAY. AFOREMENTIONED SHORT WAVE TROUGH PHASES WITH SOUTHERN SYSTEM...WHILE HIGH PRESSURE BUILDS OVER THE WESTERN HALF OF THE NATION. WL GO ALONG WITH A DRY FORECAST THROUGH NEXT THURSDAY.

TEMPERATURE-WISE...SMALL DIURNAL TEMPERATURE FLUCTUATIONS TODAY. A SLIGHT WARMUP ON SUNDAY.

&&

.AVIATION...UPDATE FOR 12Z TAF CYCLE PRIMARY AVIATION CONCERN IS TIMING THE DEPARTURE OF IFR/MVFR CIGS ACROSS ERN MN AND WRN WI. AS THE LOW PRESSURE SYSTEM PULLS NORTHEAST FROM THE UPPER LAKES...IT WILL TAKE MOST OF THE LOW LEVEL MOISTURE WITH IT. LATEST TAMDAR SOUNDINGS FROM AIRCRAFT INTO MSP SHOW INVERSION AT 3 TO 4K FT WITH SATURATION BELOW. CLIMATOLOGY OF SIMILAR MORNINGS AT MSP OFFER 75 PERCENT CONFIDENCE OF IFR CIGS REMAINING IN PLACE UNTIL 15Z. SO HAVE FOLLOWED CLOSELY TO THESE LINES FOR MSP TAF AND THINK AFTER THIS TIME LOW LEVEL FLOW WILL INCREASE ENOUGH TO AID IN SCOURING OF CLOUDS. WI TAF SITES SHOULD SEE SIMILAR BREAKING OF 800 TO 1200 FT DECKS FROM 16 TO 18Z. NORTHWEST FLOW BEHIND DEPARTING SYSTEM WILL OFFER WINDS IN EXCESS TO 12KTS AT TIMES THIS AFTN BEFORE QUICKLY DROPPING THIS EVE.

&&

.MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. &&

$$

.UPDATE...

HIGH CLOUDS CONTINUING TO ADVANCE NORTHWARD OVER THE MID SOUTH THIS MORNING AND A HIGH LEVEL OVERCAST DECK WILL COVER THE ENTIRE AREA BY MID-DAY. WITH THIS IN MIND...HAVE UPDATED SKY COVER TO MOSTLY CLOUDY AREAWIDE FOR THE REMAINDER OF TODAY. ALSO LOWERED TEMPS A FEW DEGREES AS MOISTURE INCREASES FROM THE SOUTH AND ATTEMPTS TO SATURATE THE DRY LOWER LAYERS OF THE ATMOSPHERE (AS SEEN FROM 12Z REGIONAL/ACARS SOUNDINGS) AND INDUCES SOME EVAPORATIVE COOLING. OTHERWISE...OTHER GRID ELEMENTS LOOK GOOD.

HAVE UPDATED THE GRIDS ALREADY AND WILL SEND NEW ZONE FORECAST PACKAGE SHORTLY.

&&

.MEG WATCHES/WARNINGS/ADVISORIES... AR...NONE. MO...NONE. MS...NONE. TN...NONE. &&

$$

JLH

.SYNOPSIS...WEAK HIGH PRESSURE ALOFT WILL BRIEFLY RETURN TO THE INLAND NORTHWEST TODAY...BEFORE YET ANOTHER FAST MOVING STORM SYSTEM MOVES OFF THE PACIFIC OCEAN AND INTO THE PACIFIC NORTHWEST THROUGH MONDAY. THIS INCOMING STORM PROMISES TO BRING ANOTHER ROUND OF WINTRY PRECIPITATION TO THE AREA...INCLUDING SNOW FOR MANY AREAS TONIGHT... BEFORE SNOW LEVELS RISE MONDAY AND KEEP THE BEST SNOWS LIMITED TO THE MOUNTAINS. FREEZING RAIN OR SLEET WILL BE POSSIBLE FOR THE NORTHERN HALF OF EASTERN WASHINGTON AND NORTH IDAHO LATE TONIGHT...BEFORE CHANGING TO RAIN.

&&

.DISCUSSION... TODAY THROUGH MON (XMAS)...WITH THE NEXT CYCLONE APPROACHING THE PAC NW COAST TODAY...IMMEDIATE ATTENTION WILL BE GIVEN TO THE LEAD WARM- FRONT THAT ORIENTS ITSELF SW-NE ACROSS ERN WA LATE TODAY AND TONIGHT. STRENGTH OF THE WARM-FRONT AND THE STEEPNESS OF THE SLOPE OF THE ISENTROPIC SFCS N OF A LINE FROM KEAT TO KMWH AND KGEG WILL BE ENHANCED GREATLY BY THE DEEP COOL AIR-MASS DAMMED AGAINST THE E SLOPES OF THE CASCADES AND NW BASIN ZONES ON PRE-FRONTAL SELY FLOW UP TO ABOUT 800 MB. THERMODYNAMIC PROFILES AND QPF SUPPORT THE MENTION OF ACCUMULATING SNOWS AS LOW AS 1500 FT MSL TONIGHT AND MON MORNING FROM THE OKANOGAN VLY AND W INTO THE METHOW AND CHELAN VLYS. GIVEN THE DEPTH OF THE COLDER AIR CRAMMED UP AGAINST THE CASCADES THROUGH MON MORNING...WE`VE ISSUED A SNOW ADVSY FOR THE OKANOGAN VALLEY AS WELL AS THE E SLOPES OF THE CASCADES. AS THE WARM AND COLD- FRONT TRACK E THRU ERN WA AND N ID MON...SNOW LEVELS...BASED ON LOWER WET BULB ZERO HTS AND TEMPS IN THE 850 TO 800 MB LYR WILL BE LOW ENUF TO MENTION ACCUMULATIONS DOWN TO MOST VALLEY TOWNS FOR MY ZONES THAT BORDER THE CANADIAN BORDER MON MORNING. BY LATE MORNING...HOWEVER... SNOW LEVELS SHOULD RISE MARKEDLY FOR THESE ZONES AS THE LOW-LEVEL THERMAL RIDGE DEVELOPS AND SURGES NWD NICELY ON 850MB WINDS OF 40 KT. BIG CHALLENGE...ESPECIALLY WITH NEW SNOW ON THE GROUND...WILL BE LOCATING THE BEST CHANCE FOR FREEZING PCPN OR SLEET ONCE THE TEMPS ALOFT WARM TO ABOVE FREEZING. WILL LEAN ON THE SIDE OF KEEPING SFC TEMPS COOLER LIKE THE GFS GUIDANCE...AS PUT IN A MENTION OF FREEZING RAIN OR SLEET MON MORNING FROM SPOKANE N TO BC. HOLDING ON TO THIS SFC COLD AIR...ESPECIALLY FOR THE DEEPER VALLEYS OF NE WA...THE GREATER THREAT FOR ANY ICING WILL GENERALLY BE N OF A LINE FROM KDEW TO KSZT MON. FOR THIS REASON...WE`VE ISSUED WINTER STORM WATCHES TO TAKE INTO ACCOUNT THIS MIXED PCPN FOR THE VALLEYS...AS WELL AS PSBL HEAVY SNOW ACCUMULATIONS IN THE MOUNTAINS ABOVE 4000 FT MSL MON. BZ

MONDAY NIGHT THROUGH SATURDAY...THE PATTERN REMAINS RATHER ACTIVE ...ESPECIALLY IN THE NEARER TERM OF THE PERIOD. GUIDANCE IS IN GOOD AGREEMENT THROUGH ABOUT WEDNESDAY TO WED NIGHT. THEREAFTER...MODELS BEGIN TO DIVERGE AND CONFIDENCE WANES. MONDAY NIGHT FEATURES A WEAKENING SYSTEM AND SLIGHT S/W RIDGING TOWARD TUESDAY MORNING...AHEAD OF YET ANOTHER LOW DEVELOPING OFF THE PACIFIC COAST. THAT NEXT LOW APPROACHES THE COAST BY 00Z WEDNESDAY (ENSEMBLE GUIDANCE PLACES IT NEAR 45N 135 W BY THAT TIME). THE LOW THEN TRACKS SOUTH...WITH A PRONOUNCED TROWAL FEATURE/OCCLUDED FRONT MOVING OVER THE REGION LATE TUESDAY NIGHT INTO WED AM. THIS BEGINS TO TRACK EAST LATER WED INTO THURSDAY. THIS IS WHERE MODEL CONSISTENCY AND CONFIDENCE WANES...FOR BY THURSDAY A 500MB RIDGE IS DEPICTED AS BUILDING IN...ALONG WITH SFC HIGH PRESSURE CENTERED NORTH IN BC AND THIS WOULD GENERATE A MORE NORTHERLY LOW LEVEL FLOW AND HAVE AN IMPACT (OBVIOUSLY) ON THE TEMPERATURES OVER THE REGION. OVERALL FORECAST FEATURES WANING PRECIP CHANCES INTO TUESDAY. POPS THEN INCREASE AGAIN TUESDAY NIGHT INTO WEDNESDAY...ESPECIALLY LATE TUESDAY NIGHT....WITH THE AFOREMENTIONED OCCLUDED FRONT MOVING THROUGH. THEN PRECIPITATION CHANCES WANE AGAIN INTO THURSDAY. PRECIPITATION CHANCES WERE REDUCED ON THURSDAY FOR THE MORE PRONOUNCED RIDGE ON THE GFS/CANADIAN/ECMWF MODELS...THOUGH THIS IS A MUCH MORE AMPED UP RIDGE THAN HAS BEEN DEPICTED AS OF LATE. BY THE END OF THE PERIOD ANOTHER LOW APPROACHES...TRACKING FURTHER NORTH...DRAWING ANOTHER COLD FRONT AND HIGHER PRECIPITATION CHANCES FRIDAY INTO SATURDAY (AS COMPARED WITH THURSDAY). NOT A LOT OF CHANGES MADE FOR FRIDAY INTO SATURDAY AS IS. OVERALL TEMPERATURES REMAIN NEAR AVERAGE THIS PERIOD. REDUCED HIGHS A BIT ON THURSDAY DUE TO THE MORE NORTHERLY SFC FLOW DEPICTED. /JCOTE

&&

.AVIATION...EXTENSIVE PRECIPITATION SHIELD WEST OF THE CASCADES LATE THIS MORNING SHOULD REACH THE EAST SLOPES BY EARLY AFTERNOON...WITH PRECIPITATION INCREASING IN COVERAGE AND EXPANDING EASTWARD AFTER 22Z WITH WIDESPREAD MVFR CIGS/VSBYS EXPECTED. BULK OF THE PRECIPITATION INCLUDING AREAS OF IFR CONDS EXPECTED BETWEEN 00Z AND 12Z CHRISTMAS DAY. MEANWHILE...AREAS OF FOG AND STRATUS WILL CONTINUE TO PLAGUE THE VALLEYS OF NE WA AND NORTH ID WHERE SURFACE BASED INVERSIONS WILL REMAIN STRONG THROUGH THE AFTERNOON. KJ

&&

.PRELIMINARY POINT TEMPS/POPS... SPOKANE 32 26 35 25 33 26 / 0 100 80 10 10 40 COEUR D`ALENE 33 26 36 26 33 27 / 0 100 90 20 10 40 PULLMAN 35 30 37 27 35 30 / 0 80 90 20 10 40 LEWISTON 39 33 44 30 40 33 / 0 60 70 30 10 40 COLVILLE 32 22 33 24 33 25 / 0 100 90 20 10 50 SANDPOINT 34 22 33 26 34 27 / 0 100 100 20 10 40 KELLOGG 33 24 33 25 35 28 / 0 100 100 40 10 40 MOSES LAKE 34 26 35 24 34 27 / 10 90 40 10 10 50 WENATCHEE 31 25 34 25 33 26 / 40 90 50 10 10 50 OMAK 30 24 32 23 33 24 / 30 100 60 10 10 40

&&

.OTX WATCHES/WARNINGS/ADVISORIES... ID...WINTER STORM WATCH FROM LATE TONIGHT THROUGH MONDAY AFTERNOON FOR CENTRAL PANHANDLE MOUNTAINS...NORTHERN PANHANDLE.

WA...SNOW ADVISORY FROM 4 PM THIS AFTERNOON TO 10 AM PST MONDAY FOR EAST SLOPES NORTHERN CASCADES.

WINTER STORM WATCH FROM THIS EVENING THROUGH MONDAY MORNING FOR OKANOGAN HIGHLANDS.

SNOW ADVISORY FROM 10 PM THIS EVENING TO 10 AM PST MONDAY FOR OKANOGAN VALLEY.

WINTER STORM WATCH FROM THIS EVENING THROUGH MONDAY AFTERNOON FOR NORTHEAST MOUNTAINS.

&&

$$

AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SEATTLE WA 900 AM PST SUN DEC 24 2006

.SYNOPSIS...RAIN WILL REACH THE COAST THIS MORNING AND SPREAD ACROSS WESTERN WASHINGTON THIS AFTERNOON...WITH A VIGOROUS FRONT MOVING THROUGH THIS EVENING. MOSTLY CLOUDY CONDITIONS WILL FOLLOW THE FRONT CHRISTMAS DAY WITH A CHANCE OF SHOWERS. A WEAKER FRONT WILL AFFECT THE AREA TUESDAY NIGHT...WITH ANOTHER FRONT PROBABLY ARRIVING BY THE END OF THE WEEK.

&&

.SHORT TERM...WIND ADVISORY SEEMS TO BE WORKING OUT SO FAR. SNOQUALMIE RIVER BRIDGE WIND SENSOR EAST OF NORTH BEND SHOWING SUSTAINED WIND IN THE MID 20S AND GUSTS IN THE MID 40S. GOLD BAR HAS HAD A GUST TO 38 MPH. WILL KEEP THAT GOING INTO THIS EVENING...AND WATCH OBS CAREFULLY IN CASE WIND INCREASES. NOTE THAT CROSS CASCADES GRADIENT IS NOW 12 MB OR MORE.

RAIN HAS ALREADY DEVELOPED ON THE COAST AND SEEMS SURE TO SPREAD INLAND EARLY THIS AFTERNOON. SATELLITE IMAGERY SHOWS FRONT MOVING SWIFTLY TOWARD COAST. SHOULD BE A WET NIGHT...WITH SHOWERS ON CHRISTMAS DAY. SHOWERS TAPER ON TUE THEN A WARM FRONTAL FEATURE MOVES FROM SOUTH TO NORTH ON TUE NIGHT. BURKE

&&

.LONG TERM...PREVIOUS DISCUSSION...CONFIDENCE IN THE LONGER RANGE IS LOW. WITH THE MOST RECENT RUNS THE LONGER RANGE MODELS CAME INTO FAIRLY GOOD AGREEMENT. HOWEVER THEY DIFFER DRAMATICALLY FROM PREVIOUS RUNS. THE GFS...WHICH PREVIOUSLY SHOWED A FAIRLY VIGOROUS FRONT REACHING THE AREA AROUND THU...NOW SHOWS AN UPPER RIDGE AT THAT TIME. IN COORDINATION WITH SURROUNDING OFFICES I AM LEANING SLIGHTLY TOWARD THE NEWER SOLUTIONS -- AND CLIMATOLOGY -- BUT NOT MAKING WHOLESALE CHANGES TO THE EXTENDED. MCDONNAL

&&

.AVIATION...STRONG COLD FRONT APPROACHING THE COAST...FROPA COAST AROUND 01Z AND PUGET SOUND AROUND 04Z. EXPECT CIGS TO DROP TO MVFR AROUND 21Z WHEN PRECIP AHEAD OF THE FRONT REACHES THE AREA. CIGS WILL LOWER BEHIND THE FRONT WHEN ONSHORE FLOW TAKES OVER. EASTERLY FLOW-CASCADE GAP WINDS WILL AFFECT SOME AIRPORTS EAST OF PUGET SOUND UNTIL A LITTLE BEFORE FROPA.

KSEA...TAF IS ON TRACK...THOUGH 18Z MAY BE AN HOUR OR TWO EARLY FOR PRECIP TO BEGIN AT THE SURFACE...VIRGA ALOFT THOUGH. ACARS SHOWS LOW LEVEL WINDS HAVEN`T RAMPED UP YET...BUT SAND POINT-LAKE WA PROFILER SHOWS SE 35KT AT FL020. NAM STILL SHOWS S45-50KT AT FL025 ABOVE KSEA BETWEEN 18Z-03Z. WILL TAKE CIGS DOWN TO AROUND BKN025 AFT 21Z. KAM

&&

.SEW WATCHES/WARNINGS/ADVISORIES... .WIND ADVISORY EAST PUGET SOUND LOWLANDS...ADMIRALTY INLET AREA... STRAIT OF JUAN DE FUCA 8 AM THROUGH 6 PM TODAY. .WINTER WEATHER ADVISORY CASCADES NOON TODAY THROUGH MIDNIGHT TONIGHT. .GALE WARNING COAST...ENTRANCES TO THE STRAIT...ADMIRALTY INLET AND NORTH INLAND WATERS FROM CAMANO ISLAND TO POINT ROBERTS. .SMALL CRAFT ADVISORY GRAYS HARBOR BAR FOR ROUGH BAR CONDITIONS UNTIL FURTHER NOTICE.

$$

WEATHER.GOV/SEATTLE

.SYNOPSIS...HOLIDAY TRAVELERS SHOULD PREPARE FOR SNOWY DRIVING CONDITIONS THIS WEEKEND. A STORM SYSTEM WILL BRING LIGHT TO MODERATE SNOW ACCUMULATIONS TO MUCH OF THE INLAND NORTHWEST TODAY AND TONIGHT. ANOTHER STORM SYSTEM WILL SPREAD PRECIPITATION ACROSS THE REGION SUNDAY NIGHT AND CHRISTMAS DAY.

&&

.DISCUSSION... TODAY AND TONIGHT...IMMEDIATE ATTENTION WILL BE GIVEN TO THE LEAD WARM-FRONT THAT IS ORIENTING ITSELF ROUGHLY E-W ACROSS THE COLUMBIA BASIN ATTM. STRENGTH OF THE WARM-FRONT AND THE STEEPNESS OF THE SLOPE OF THE ISENTROPIC SFCS WILL BE ENHANCED GREATLY BY THE DEEP COOL AIR- MASS DAMMED AGAINST THE E SLOPES OF THE CASCADES AND NW BASIN ZONES ON PRE-FRONTAL SELY FLOW SO FAR THIS MORNING. THERMODYNAMIC PROFILES AND QPF SUPPORT THE MENTION OF ACCUMULATING SNOWS DOWN TO ALL VLY FLOORS THIS MORNING...WHICH WILL COINCIDE WITH THE HEAVIEST PCPN OF THE FAST-MOVING, AND WEAKENING, CYCLONE AS IT MOVES THRU THE PAC NW TODAY. SNOW AMNTS APPEAR TO BE A BIT OVERDONE ON GUIDANCE...BASED ON THE RATHER HIGH CEILINGS ON SFC OBS AND THE DRY LYR BELOW THE CANOPY OF STRATIFORM PCPN NOW MOVING ACROSS THE CASCADES. FOR THE COLUMBIA BASIN...WE`LL HAVE TO MONITOR CLOSELY TO SEE IF THE CURRENT SHEARING AND WEAKENING OF THE UPPER TROF SHOWN ON SATELLITE IS ENUF TO DISCONTINUE THE ADVSY FOR THE BASIN ZONES. WILL ALSO WATCH FOR MIXED PCPN FOR THE EXTREME SRN BASIN REGION WITH WARMING TEMPS JUST ABOVE THE SFC NOW NOSING INTO THE REGION ON DEVELOPING LOW-LEVEL THERMAL RIDGE. FOLLOWING FROPA THIS MORNING...POST-FRONTAL WLY FLOW WILL SHUT OFF THE PCPN THREAT FOR THE BASIN ZONES BUT...GIVEN THE INCREASING INSTABILITY LATER TODAY AND ESPECIALLY TONIGHT...SHOULD ACT TO CONTINUE THE SNOW ACCUMULATION THREAT FOR THE N ID MTNS ZONES. BZ

SUNDAY THROUGH TUESDAY...MODEL INITIALIZATIONS LOOKED TO HAVE DIFFICULTY WITH SEVERAL FEATURES THAT WILL IMPACT THE CWA THROUGH THE PERIOD. PV ANOMALIES NEAR 45N/140W...55N/140W...45N/155W WERE ALL VERY POORLY DEPICTED BY THE NAM...GFS...AND UKMET. THE GENERAL IDEA OF TROUGHING FOR EACH OF THESE FEATURES WAS AT LEAST INDICATED BY MOST GUIDANCE. IN WORKING INTO THE FORECAST PERIOD A BIT AT 500 MB...IT SEEMS MOST GLOBAL GUIDANCE FALLS PRETTY CLOSELY INTO STEP BY AND THROUGH 60 HOURS...THAT IS EXCEPT THE NAM. IT FOLLOWS INTO ITS NORMAL BIAS OF OVERDEVELOPING A 500 MB LOW OFF THE PACIFIC COAST AND SAGGING THE SAID LOW TOO FAR TO THE SOUTH SUCH THAT IT IS OUTSIDE THE ENVELOPE OF ALL GFS ENSEMBLE MEMBERS AND QUITE A BIT SLOWER THAN ANY OTHER PIECE OF GLOBAL GUIDANCE. IT HAS THEREFORE BEEN SUMMARILY DISMISSED AND RENDERED RELATIVELY USELESS FOR THE FORECAST PERIOD.

NOW FOR THE SHORT WAVE DETAILS OF THE PERIOD...WITH GOOD AGREEMENT AMONGST THE GFS...CANADIAN...UKMET...AND ECMWF...A STRONG PACIFIC CLOSED LOW SHOULD BE APPROACHING THE COAST BY 00Z MONDAY. WITH GOOD DIFFLUENCE ON ALL MODELS APPROACHING THE CWA BY 00Z MONDAY...AND THE GFS SHOWING SIGNS OF MOISTURE TRANSPORT AND ISENTROPIC ASCENT ENCROACHING ON THE CASCADES IN THE 290-300K LAYER SHORTLY AFTER 00Z...BEGAN TO INDICATE POPS FROM WEST TO EAST STARTING ABOUT 06Z. SEVERAL COMPLICATING FACTORS WITH THIS SYSTEM MAKE ITS EVOLUTION...P-TYPE...AND VERTICAL THERMAL PROFILE STILL VERY DIFFICULT TO PIN DOWN AT THIS JUNCTURE. AS LIFT ENTERS AREA...SIGNIFICANT DRY AIR WILL HAVE TO BE OVERCOME BETWEEN 850 AND 600 MB. THE GFS IS VERY AGGRESSIVE IN OVERCOMING DEWPOINT DEPRESSIONS IT INDICATES IN THIS LAYER OF UP TO 50C. WHILE THIS VALUE IS PROBABLY RIDICULOUSLY OVERDONE...THE GENERAL IDEA OF OVERCOMING A SIGNIFICANT DRY LAYER IN THE SOUNDING INITIALLY LEADS ONE TO BELIEVE THAT A WET BULB EFFECT SHOULD ENSURE SNOWFALL FOR THE MAJORITY OF THE CWA FOR CHRISTMAS DAY. HOWEVER...WITH A DECENT TAP OF PACIFIC AIR AND STRONG FLOW THROUGH THE COLUMBIA GORGE AND GOOD WARM ADVECTION AT 850 MB...THIS IS NOT AS STRAIGHTFORWARD AS IT MAY SEEM. WITH SOUNDINGS QUICKLY MOISTENING UP AS FLOW JUST OFF THE DECK GOES SOUTHWESTERLY...DO NOT BELIEVE WET BULB EFFECTS WILL BE APPRECIABLE FOR MOST AREAS...ESPECIALLY NOT IN THE BOUNDARY LAYER...SO BELIEVE P-TYPE WILL LARGELY BE DICTATED BY HOW WARM THE BOUNDARY LAYER IS AT THE ONSET OF THE EVENT AND HOW MUCH LOW-LEVEL WARM AIR CREEPS INTO THE LOWER BASIN. AT THE MOMENT...IT SEEMS FROM THE PALOUSE SOUTHWARD AN INITIAL SHOT OF SNOW WILL PROBABLY MIX WITH RAIN AND CHANGE TO RAIN IN THE LOWER ELEVATIONS BEFORE QUICKLY ENDING IN THE AFTERNOON ON CHRISTMAS. FOR THE AREAS AROUND SPOKANE AND NORTH...WITH LIFT COMING THROUGH PRIMARILY IN THE MORNING...P-TYPE SHOULD BEGIN AS SNOW. BY 18Z HOWEVER...DRY SLOT IN THE 700-500 MB LAYER BEGINS TO MOVE INTO THE AREA. WITH POOR NUCLEATION AND WEAK SEEDER-FEEDER MECHANISM...ICE CRYSTAL FORMATION WILL BE HARD TO ACCOMPLISH GIVEN INSUFFICIENT SATURATION WITH RESPECT TO ICE IN THE MAIN CLOUD LAYER. HOWEVER...WITH STILL STRONG MOISTURE IN PLACE BELOW AS BEST LIFT PULLS OUT TO THE NORTHEAST...POTENTIAL FOR DRIZZLE OR FREEZING DRIZZLE STILL EXISTS AS DRY SLOT ENDS SNOW CHANCES. THIS WILL NEED TO BE MONITORED AS TEMPERATURES LOOK TO BE RIGHT AROUND OR JUST ABOVE THE CRITICAL FREEZING MARK DURING THE AFTERNOON ON CHRISTMAS DAY. FOR AREAS FARTHER EAST INTO IDAHO...WITH SUFFICIENT LIFT AND THE LATER ARRIVAL OF THE DRY SLOT...SNOW CHANCES SHOULD CONTINUE FOR ALL HIGHER ELEVATIONS...WITH RAIN PROBABLY TOWARD THE L.C. VALLEY.

AS THE SYSTEM PULLS EAST MONDAY NIGHT...DESCENT GENERALLY DEPICTED BY MOST GUIDANCE BY TUESDAY WITH ONLY MEAGER ISENTROPIC ASCENT WITH LITTLE MOISTURE TRANSPORT OVER THE CASCADES AND NORTHEASTERN CWA MOUNTAINOUS AREAS. REALLY DO NOT EXPECT MUCH MORE THAN A SNOW SHOWER OR TWO OUT OF THIS PATTERN AS SYNOPTIC LIFT HAS REALLY DEPARTED CWA BY THIS POINT.

FOR TEMPERATURES THROUGH THE PERIOD THERE WERE SIGNIFICANT DISCREPANCIES BETWEEN MOS GUIDANCE NUMBERS. THE MET WAS SIGNIFICANTLY WARMER FOR MONDAY THAN THE MAV AND MEX. GIVEN THE MAV AND MEX MOVEMENT TOWARD SIGNIFICANTLY COLDER NUMBERS THAN THE LAST SEVERAL DAYS FOR MONDAY...HEDGED ABOVE THE MAV. OTHERWISE...TEMPERATURES FOR THE PERIOD SHOULD BE WITHIN A COUPLE DEGREES OF THE MAV AS THE GFS TENDED TO HAVE A DECENT HANDLE ON THE SYNOPTIC EVOLUTIONS THROUGH THE PERIOD.

BEYOND TUESDAY...MODEL SOLUTIONS BEGIN TO DIVERGE SIGNIFICANTLY WITH LITTLE CONFIDENCE IN ANY TIMING OF SHORT WAVE PROGRESSION. GIVEN UNCERTAINTY AND LITTLE CONFIDENCE IN ANY CHANGES...LEFT GOING EXTENDED FORECAST INTACT. /FRIES

&&

.AVIATION... FORECAST DOMINATED BY INCOMING WINTER OCCLUDED FRONT WHICH WILL IMPACT THE ENTIRE REGION THROUGH 18Z TODAY...WITH WIDESPREAD IFR CEILINGS AND VIS IN SNOW...WITH MODERATE IMPROVEMENT TO MVFR CIG/VIS SCATTERED SNOW SHOWERS AFTER 18Z THROUGH 06Z SUNDAY. IDAHO PANHANDLE WILL REMAIN MOSTLY IFR CIG/VIS IN NUMEROUS SNOW SHOWERS WITH EXTENSIVE MOUNTAIN OBSCURATIONS THROUGH 06Z SUNDAY.

&& .PRELIMINARY POINT TEMPS/POPS... SPOKANE 31 23 31 26 34 25 / 100 20 0 70 60 10 COEUR D`ALENE 32 25 32 26 35 26 / 100 30 0 70 60 20 PULLMAN 35 26 34 30 36 27 / 100 40 0 70 60 20 LEWISTON 40 30 37 33 43 30 / 90 40 0 60 60 30 COLVILLE 30 22 31 22 32 24 / 100 10 0 80 50 20 SANDPOINT 29 25 32 22 32 26 / 100 40 0 60 70 20 KELLOGG 29 25 31 24 32 25 / 100 70 0 60 70 40 MOSES LAKE 32 23 31 26 34 24 / 90 10 0 60 40 10 WENATCHEE 29 24 29 25 33 25 / 90 10 0 60 40 10 OMAK 29 20 28 24 31 23 / 100 20 0 60 40 10

&&

.OTX WATCHES/WARNINGS/ADVISORIES... ID...SNOW ADVISORY UNTIL 3 PM PST THIS AFTERNOON FOR COEUR D`ALENE AREA...IDAHO PALOUSE.

SNOW ADVISORY UNTIL 10 PM PST THIS EVENING FOR CENTRAL PANHANDLE MOUNTAINS...NORTHERN PANHANDLE.

WA...SNOW ADVISORY UNTIL NOON PST TODAY FOR OKANOGAN HIGHLANDS.

SNOW ADVISORY UNTIL 3 PM PST THIS AFTERNOON FOR SPOKANE AREA... WASHINGTON PALOUSE.

WINTER WEATHER ADVISORY UNTIL NOON PST TODAY FOR MOSES LAKE AREA...UPPER COLUMBIA BASIN.

SNOW ADVISORY UNTIL 10 PM PST THIS EVENING FOR NORTHEAST MOUNTAINS.

SNOW ADVISORY UNTIL 10 AM PST THIS MORNING FOR OKANOGAN VALLEY...WATERVILLE PLATEAU...WENATCHEE AREA.

SNOW ADVISORY UNTIL 4 PM PST THIS AFTERNOON FOR EAST SLOPES NORTHERN CASCADES.

&&

$$

AREA FORECAST DISCUSSION...CORRECTED NATIONAL WEATHER SERVICE SEATTLE WA 300 AM PST SAT DEC 23 2006

.SYNOPSIS...A FRONTAL SYSTEM OVER WESTERN WASHINGTON WILL MAKE ITS WAY EAST OF THE CASCADES TODAY...WITH RAIN GIVING WAY TO SCATTERED SHOWERS. TONIGHT AND SUNDAY WILL BE MOSTLY DRY ...BUT WINDY CONDITIONS WILL DEVELOP OVER THE EAST PUGET SOUND LOWLANDS. ANOTHER FRONT WILL BRING MORE RAIN SUNDAY NIGHT...WITH A CHANCE SHOWERS ON CHRISTMAS. ANOTHER FRONT WILL ARRIVE DURING THE MIDDLE OF THE WEEK.

&&

.SHORT TERM...A FRONTAL BAND...ASSOCIATED WITH A MATURE LOW CENTERED IN THE GULF OF ALASKA...EXTENDS FROM NORTHERN BRITISH COLUMBIA ACROSS VANCOUVER ISLAND AND THROUGH THE COASTAL WATERS OF THE PACIFIC NORTHWEST. THE SURFACE FRONT WILL MOVE QUICKLY INLAND THIS MORNING AND INTO THE CASCADES BY NOON TODAY. ONE SHORT TERM PROBLEM IS THAT THE SNOW LEVEL HAS LOWERED TO THE SURFACE IN THE HOOD CANAL AREA THIS MORNING. SHELTON HAS REPORTING SNOW FOR THE PAST COUPLE HOURS AND THE TEMP HAS FALLEN TO 32 DEGREES...AND A SPOTTER IN UNION CALLED IN WITH THREE AND A HALF INCHES. I WILL ISSUE A HEAVY SNOW WARNING FOR THE EARLY MORNING.

A SMALL WAVE THAT DEVELOPED ON THE FRONTAL BAND FRI EVENING IS MAKING ITS WAY INTO EXTREME NORTHWEST OREGON. THE MODELS DON`T HAVE A GREAT HANDLE ON THIS FEATURE AND THEIR PLACEMENT OF THE SURFACE DEPRESSION ALONG THE FRONT MAY BE OFF SOMEWHAT. AT ANY RATE THE GALES ALONG THE COAST AND NORTHERN INLAND WATERS WILL GAVE WAY TO LIGHTER WINDS THIS MORNING AS THE FRONT MOVES INLAND.

THE MODELS HAVE BEEN CONSISTENT IN DRYING THINGS OUT FAIRLY QUICKLY BEHIND THE FRONT LATER TODAY...AND I WILL STAY WITH THE FORECAST IDEA THAT SHOWERS WILL TAPER OFF THIS AFTERNOON AND EVENING. THE UPPER RIDGE AHEAD OF THE NEXT DEEP SYSTEM UPSTREAM WILL MOVE INTO WRN WA LATE TONIGHT AND EAST OF THE CASCADES SUN MORNING.

THE APPROACH OF THE NEXT FRONTAL SYSTEM WILL CREATE A STRONG EASTERLY GRADIENT ACROSS THE STATE SUN...AS PREVIOUS DISCUSSIONS HAVE MENTIONED. NOT ONLY WILL THIS PRODUCE ANOTHER ROUND OF SOLID GALES OVER MUCH OF THE MARINE WATERS...THERE IS A POSSIBILITY OF LOCALIZED HIGH EAST WINDS ALONG THE FOOTHILLS OF THE CASCADES. THE 4 KM MM5 SOLUTION SHOWS AREAS OF 35 KT WIND DEVELOPING SUN AFTERNOON ...AND MOUNTAIN WAVE ACTIVITY CAN`T BE RULED OUT EITHER. I WILL REPLACE THE SPECIAL WEATHER STATEMENT ABOUT THIS WITH A HIGH WIND WATCH FOR THE EASTERN PUGET SOUND LOWLAND ZONE.

THE FRONT WILL MOVE INLAND SUN NIGHT...AND RAIN WILL GIVE WAY TO SHOWERS ON CHRISTMAS DAY. MCDONNAL

&&

.LONG TERM...AGREEMENT BETWEEN MODELS IN THE LONGER RANGE IS NOT VERY GOOD. HOWEVER THE GFS HAS BEEN REASONABLY CONSISTENT WITH THE IDEA THAT THE NEXT FRONT WILL ARRIVE AROUND WED...WITH FRONTAL WAVES KEEPING RAIN OVER THE AREA INTO THU. THE CURRENT FORECAST FOR TUE THROUGH FRI LOOKS GOOD GIVEN THE MARGINAL LEVEL OF CONFIDENCE AT THIS TIME. MCDONNAL

&&

.AVIATION....A STRONG FRONT ASSOCIATED WITH A 1006 MB LOW MOVING N THRU THE COASTAL WATERS WILL SWEEP THROUGH THE AREA EARLY THIS MORNING...BETWEEN 12Z AND 15Z. WHILE THE SURFACE LOW APPEARS TO BE TRACKING N ALONG THE COAST...UPPER LEVEL ENERGY IS SWEEPING INLAND ACROSS NRN OREGON AND CUTTING OFF THE STRONG SLY FLOW ALOFT. THIS IS CONFIRMED BY ACARS SOUNDINGS OUT OF KSEA SHORTLY AFTER MIDNIGHT. HENCE WILL REMOVE LLWS FROM THE W WA TERMINALS EARLY THIS MORNING. PRECIPITATION IS OVERWHELMING THE STRONG ELY FLOW ACROSS THE CASCADES SO WILL STAY WITH CURRENT OVC025-030 CONDITIONS BEFORE FROPA...THEN GO WITH NEAR BKN010 OVC025 CONDITIONS IN POST FRONTAL ONSHORE FLOW THRU ABOUT 20Z. CONDITIONS WILL RAPIDLY IMPROVE AFT 20Z AS HIGH PRES AT THE SURFACE AND ALOFT BUILDS OVER THE AREA AND THE AIR MASS DRIES.

IT APPEARS THAT THE AIR MASS WILL BE DRY ENOUGH TONIGHT WITH INCREASING OFFSHORE PRES GRADIENTS TO KEEP FG OR LOW STRATUS OUT OF MOST TERMINALS...EXCEPT OF COURSE KOLM.

WIND AT KSEA WILL VARY FROM SLY TO ELY UNTIL FROPA 12Z-15Z TIME FRAME THEN 20012G20KT BEHIND THE FRONT THIS MORNING BEFORE SETTLING DOWN TO 19007KT THIS AFTERNOON BACKING TO 09005KT BY LATE TONIGHT. ALBRECHT

&&

.MARINE...WILL MAINTAIN GALES EARLY THIS MORNING FOR THE COAST...ENTRANCES...ADMIRALTY INLET...AND N INLAND WATERS UNTIL THE OFFSHORE WAVE LIFTS NE OF THE AREA. A BRIEF PERIOD OF POST FRONTAL ONSHORE SCA CONDITIONS IN STORE FOR THE STRAIT AND PUGET SOUND MARINE ZONES THIS MORNING BEFORE PRES GRADIENTS SETTLE DOWN. WHILE WINDS WILL COME DOWN ON THE COAST LATER TODAY...HAZARDOUS SEAS WILL CONTINUE THRU TONIGHT FOLLOWED BY INCREASING OFFSHORE GRADIENTS FOR SCA WINDS AGAIN COAST TOWARD SUN MORNING. WIDESPREAD GALES COAST...ENTRANCES AND ADMIRALTY INLET ARE IN STORE BY SUN AFTERNOON AS THE NEXT N-S ORIENTED FRONTAL SYSTEM ARRIVES FROM THE W. ALBRECHT

&&

.SEW WATCHES/WARNINGS/ADVISORIES... .HEAVY SNOW WARNING FOR THE HOOD CANAL AREA UNTIL 6 AM THIS MORNING. .HIGH WIND WATCH FOR THE EAST PUGET SOUND LOWLANDS 10 AM SUNDAY THROUGH 8 PM SUNDAY. .GALE WARNING COAST..ENTRANCES TO THE STRAIT OF JUAN DE FUCA... NORTH INLAND WATERS FROM CAMANO ISLAND TO POINT ROBERTS...AND ADMIRALTY INLET THROUGH 7 AM. .SMALL CRAFT ADVISORY 7 AM TO 10 AM COAST...ENTRANCES TO THE STRAIT...AND NORTHERN INLAND WATERS. .SMALL CRAFT ADVISORY THROUGH 10 AM PUGET SOUND AND HOOD CANAL AND FOR THE CENTRAL STRAIT. .SMALL CRAFT ADVISORY COAST FOR HAZARDOUS SEAS 10 AM THROUGH TONIGHT. .SMALL CRAFT ADVISORY GRAYS HARBOR BAR FOR ROUGH BAR CONDITIONS UNTIL FURTHER NOTICE.

$$

.SYNOPSIS...A SERIES OF PACIFIC STORM SYSTEMS WILL KEEP THE WEATHER PATTERN UNSETTLED THROUGH NEXT WEEK.

&&

.SHORT TERM...LATEST SATELLITE IMAGERY SHOWS THE UPPER FLOW LIFTING NWD AHEAD OF A WAVE NOW APPROACHING 130W. THE NEW 00Z NAM-12 APPEARS TO HAVE INITIALIZED THE WAVE WITH POSSIBLE WEAK SFC LOW DEVELOPMENT BETTER THAN THE GFS GIVEN SATELLITE TRENDS. STRONGER DEVELOPMENT OFFSHORE MAY RESULT IN A DELAY OF PRECIP OVER THE INTERIOR AS ELY FLOW WILL CONTINUE TO DRY LOW LOW LEVELS. MAY SEE SOME VIRGA OR SPRINKLES UP TO 12Z BUT THE MAIN PRECIP EVENT WILL LIKELY BE WITH THE FRONT ITSELF 12-16Z. WINDS WILL ALSO PICK UP...ESPECIALLY ALONG THE FOOTHILLS AS ELY GAP FLOW DEVELOPS. CROSS CASCADE GRADIENT ARE UP NEAR -9MB SEA-EAT. HOWEVER...ACARS SOUNDINGS SHOW MOSTLY MOD S/SW FLOW ABOVE 900MB. THIS IS NOT CONDUCIVE FOR MOUNTAIN WAVE CONDS BUT BREEZY ELY GAP WINDS ARE POSSIBLE. DO NOT BELIEVE THIS WILL BE STRONG ENOUGH TO WARRANT A WIND ADVISORY BUT WILL NEED TO MONITOR.

WINDS WILL BECOME A LARGER PROBLEM WITH THE NEXT SYSTEM SLATED FOR SUN AFTERNOON AND SUN NIGHT. THE LATEST NAM-12 GIVES NEARLY -12MB SEA-EAT BY 00Z SUN AFTERNOON WITH SELY 850MB WINDS AROUND 30KT. THIS IS CONDUCIVE FOR SOME FAIRLY WINDY CONDITIONS ALONG THE FOOTHILLS AND AREAS EAST OF BELLEVUE. HIGH WIND POTENTIAL CONTINUES BUT WILL ALLOW THE NEXT SHIFT TO DECIDE ON A WATCH.

.LONG TERM...PREVIOUS DISCUSSION FOLLOWS...AFTER A RELATIVELY DRY DAY ON TUESDAY...WEATHER SYSTEMS REACH WASHINGTON IN QUICK SUCCESSION. CURRENTLY LOOKS LIKE WEDNESDAY...THURSDAY...AND FRIDAY NIGHT WILL EACH HAVE SEPARATE STORMS. THIS IS CLIMATOLOGICALLY THE MOST ACTIVE TIME OF YEAR AND DO NOT EXPECT ANY RELIEF FOR AWHILE. BURKE

&&

.AVIATION...STRONG COLD FRONT OFFSHORE WILL REACH THE COAST LATE TONIGHT AROUND 12Z...THEN MOVE THROUGH PUGET SOUND AROUND 15Z. SATELLITE IMAGERY SHOWS THAT THE NAM APPEARS TO SHOW THE STRUCTURE OF A WAVE CENTERED NEAR 43N/132W BETTER THAN THE GFS...AND THIS WAVE APPEARS TO BE DESTINED TO MOVE NE TOWARD THE NORTHERN OLYMPIC PENINSULA. THIS IS LIKELY TO GIVE A LITTLE MORE WIND TO THE AREA...ESPECIALLY AREAS THAT ARE SUSCEPTIBLE TO S/SELY WIND...DURING THE 12Z-15Z TIME FRAME AND MAY PROVIDE SOME LLWS TO KSEA DURING THE 09Z-15Z TIME FRAME AS SFC FLOW REMAINS E/SE AND WIND AT 020 RISES TO 18040KT.

CIGS ARE QUITE HIGH AT THIS TIME WITH LOW LEVEL PRES GRADIENTS STRONGLY OFFSHORE. WILL DELAY CIGS DECREASING UNTIL ABOUT 11Z-12Z TIME FRAME IMMEDIATELY AHEAD OF THE FRONT...AND WILL RAISE CIGS WITH FROPA TO AROUND 010 AT KSEA. CIGS WILL IMPROVE MIDDAY SAT AS POST FRONTAL ONSHORE FLOW RELAXES. AFTER ELY WIND TONIGHT AND LLWS LATE...WIND AT KSEA WILL TURN 22015G25KT AFTER THE FRONT MOVES THRU AROUND 15Z AND WILL THEN TAPER OFF DURING THE AFTERNOON HOURS. ALBRECHT.

&&

.MARINE...A WAVE DEVELOPING ON THE OFFSHORE FRONT AT 43N/132W WILL MOVE NE TO THE NORTHERN OLYMPIC PENINSULA. GIVEN THE IMPROVED STRUCTURE SEEN ON THE SATELLITE IMAGERY WITH THIS FRONT AND ASSOCIATED WAVE...WILL BOOST WIND OVER THE MARINE ZONES 5 KT LATER TONIGHT THRU SAT MORNING. THIS WILL REQUIRE THE ISSUANCE OF A GALE WARNING TO ADMIRALTY INLET AND SMALL CRAFT ADVISORY FOR PUGET SOUND AND HOOD CANAL WITH STRONGEST WIND WITH THE FRONT. ALBRECHT

&&

.SEW WATCHES/WARNINGS/ADVISORIES... .GALE WARNING COAST..ENTRANCES TO THE STRAIT OF JUAN DE FUCA... NORTH INLAND WATERS FROM CAMANO ISLAND TO POINT ROBERTS...AND ADMIRALTY INLET. .SMALL CRAFT ADVISORY LATE TONIGHT THROUGH SAT MORNING FOR PUGET SOUND AND HOOD CANAL. .SMALL CRAFT ADVISORY GRAYS HARBOR BAR FOR ROUGH BAR CONDITIONS.

$$

WEATHER.GOV/SEATTLE

.SHORT TERM UPDATE(THIS AFTERNOON)... RAIN BEGINNING TO MOVE INTO THE SOUTHERN PORTION OF FORECAST AREA. THE RAIN WILL CONTINUE TO MOVE NORTHEAST..AND WAS RUNNING INTO SOME DRIER AIR...HOWEVER THE DRY AIR WILL GIVE WAY TO INCREASING MOIST AIR THRU THE AFTERNOON. MORNING TAMDAR DATA INDICATED MOISTURE WAS WAS AROUND 10,000 TO 11,000 FEET. THE FREEZING LVL AROUND 9,000 FEET. SO PRECIPITATION WILL BE RAIN FOR THE AFTERNOON. THE ONLY CHANGES TO THE FORECAST WILL BE SOME WORDING. HIGHS RANGING FROM THE LOW TO MID 40S.

&&

.AVIATION(12Z-12Z)... RA ON TRACK IN KY EARLY THIS MORN TO SPREAD NNE ACRS NRN OH AND NW PA MNLY THIS AFTN...HWVR A FEW SPRINKLES FM MID CLDS MAY PRECEDE MAIN PRECIP SHIELD THIS MORN FM CLE TO CAK AND POINTS W. RA SHUD DCRS SOME THIS EVE THEN BGN TO CHG TO SN FM W TO E TNGT INTO TUE MORN. PRECIP INTENSITY SHUD BE LGT ENUF FOR MOST AREAS LATER TNGT WHEN CHGOVR TO SN TAKES PLACE SO THAT CIGS AND VSBY`S SHUD NOT DROP MUCH MORE...PROB STAYING HI RANGE IFR OR LOW END MVFR.

&&

.SHORT TERM(TODAY THROUGH TUESDAY NIGHT)... WELL...AFTER SHOWING SIG DIFFS THE PAST COUPLE OF DAY...THE GFS AND NAM HAVE FINALLY IN AGREEMENT WITH HANDLING OF MAIN FEATURES THIS PERIOD. UNFORTUNATELY STILL SOME QUESTIONS AS TO TIMING OF PRECIP TRANSITION FROM RAIN TO SNOW. FIRST THINGS FIRST HOWEVER...REGIONAL 88D LOOP CONTS TO SHOW PRECIP SPREADING N QUICKLY AHEAD OF SFC LOW. BOTH NAM AND GFS APPEAR A LITTLE SLOW WITH MOVEMENT OF THIS PRECIP SHIELD AND HAVE ADJUSTED FORECAST TO ALLOW PRECIP TO ARRIVE AN HOUR OR TWO EARLIER THAN PREVIOUS FORECAST PACKAGE. SFC LOW TO MOV TO NEAR KBNA BY 00Z AND TO NEAR KPIT BY 12Z TUE. PRECIP WILL CONT UNABATED WHILE THIS HAPPENS. NOT MUCH COLD AIR TO THE N OF AREA TO BE ADVECTED IN SO TRANSITION TO SNOW WILL BE SLOW. IN FACT...BOTH GFS AND NAM KEEP 1000 TO 850MB THICKNESS ABOVE 1300M TILL AROUND 12Z TUE. AT THE SAME TIME SURFACE WET BULB TEMPS FORECAST TO REMAIN CLOSE TO 35 DEG F SO FREEZING PRECIP UNLIKELY. BOTH MODELS SHOWING AREA OF SIG UVV LATE TONIGHT BUT NOT SURE IF COLUMN WILL COOL FAST ENUF FOR CHANGE TO SNOW. BUFKIT SOUNDINGS REALLY ONLY SHOWING A COUPLE HOUR PERIOD OF STRONG UVV IN THE FAVORED SNOW GROWTH REGION. IF TEMPS AT SFC AREN/T COLD ENUF DURING THE PERIOD FOR SNOW...STORM TOTAL ACCUMS WILL BE GREATLY REDUCED. GIVEN UNCERTAINITY WILL KEEP FORECAST SIMILAR TO PREVIOUS PACKAGE WITH TRANSITION OCCURING LATE TONIGHT WHICH SEEM REASONABLE GIVEN NEW GUIDANCE. ACCUMS THRU DAYBREAK TUE WILL BE SLIGHT. 850 MB TEMPS FINALLY DIP TO NEG 4 TO NEG 5 TUE AM AND THIS WILL FINALLY GET RID OF ANY REMAINING LIQUID PRECIP. ERN AREAS COULD GET A FEW INCHES OF SNOW TUE BUT WOULD BE SURPRISED TO SEE MUCH MORE THAN AN INCH TOTAL WRN AREAS. LOW WILL QUICKLY RACE OFF TO THE NE ON TUE AND DRY AIR WILL COME IN QUICK BEHIND. WILL KEEP CHC WORDING MOST OF AREA TUE WITH LIKELY IN THE SNOWBELT AS 850 MB TEMPS DIP TO AROUND NEG 850. WILL AGAIN USE A BLEND OF GUID TEMPS.

HAPPY HOLIDAYS FROM THE STAFF HERE AT WFO CLE.

&&

.LONG TERM(WEDNESDAY THROUGH SUNDAY)... ACTIVE WEATHER PATTERN SETTING UP FOR THE END OF THE YEAR AND FROM THE LOOKS OF IT...2006 IS NOT GIVING UP WITHOUT A FIGHT.

DELTA LOW THAT TRACKS UP TO THE NORTHEAST OVER THE AREA IS FORECAST TO CONTINUE MOVING NORTHEAST TO THE CANADIAN MARITIMES BY TUESDAY NIGHT. LOW PRESSURE SYSTEM WILL GRADUALLY PULL PRECIPITATION OUT OF THE AREA BY WEDNESDAY AS HIGH PRESSURE QUICKLY BUILDS NORTHEAST INTO THE AREA BY WEDNESDAY NIGHT. FAIR WEATHER WILL CONTINUE THROUGH THURSDAY MORNING AND THEN GIVE WAY TO A WARM FRONT THAT WILL MOVE INTO THE AREA DURING THE DAY THURSDAY. I WILL BRING IN A CHANCE FOR SOME SHOWERS THURSDAY AFTERNOON IN THE WESTERN THIRD OF THE FORECAST AREA WITH THE WARM FRONT. THEN...THURSDAY NIGHT I WILL LIFT THE FRONT NORTHEAST ACROSS THE AREA WITH A CONTINUE CHANCE OF SNOW SHOWERS OVER ALL AREAS EXCEPT NORTHWEST PENNSYLVANIA. THE PRECIPITATION WILL TAPER OFF FROM THE SOUTHWEST IN THE WAKE OF THE FRONT BUT WILL LIFT INTO NORTHEAST OHIO AND NORTHWEST PENNSYLVANIA BY FRIDAY MORNING.

UPPER LEVEL LOW PRESSURE SYSTEM PROGGED TO TRACK SLOWLY EAST ACROSS THE SOUTHERN TIER STATES THURSDAY INTO SATURDAY WILL FORCE A SURFACE LOW TO DEVELOP OVER THE TEXAS GULF COAST AND THEN ROTATE NORTHEAST ON THE EAST SIDE OF THE UPPER LEVEL LOW PRESSURE SYSTEM TOWARD THE FORECAST AREA. THIS SCENARIO COULD SET UP THE AREA FOR ANOTHER POTENTIAL SNOW STORM FOR THE END OF THE YEAR. THIS SITUATION SEEMS REASONABLE AS IDEAL PLACEMENT OF COLD HIGH PRESSURE IS PROGGED TO BE SITUATED OVER SOUTHERN QUEBEC PUMPING COLD AIR INTO THE REGION. THIS IS ONE OF THOSE SITUATIONS WHERE THE PRECIPITATION SLASH NO PRECIPITATION LINE COULD BISECT THE FORECAST AREA. BUT FOR NOW WILL KEEP ENTIRE AREA IN A CHANCE FOR SNOW SHOWERS SATURDAY NIGHT AND THEN BEGIN TO PULL THE PRECIPITATION OUT OF THE WEST ON SUNDAY.

ENSEMBLE AND GFS TEMPERATURES RELATIVELY CLOSE THROUGH THIS PERIOD SO STAYED PRETTY CLOSE TO THEM FOR NOW. &&

.CLE WATCHES/WARNINGS/ADVISORIES... OH...NONE. PA...NONE.

&&

$$

SHORT TERM...KUBINA LONG TERM...LOMBARDY AVIATION...ADAMS

.SHORT TERM...TODAY AND TONIGHT

WATER VAPOR IMAGERY SHOWS THE UPPER LEVEL CLOSED LOW THAT WAS IN PLACE OVER SOUTHERN ARKANSAS BEING SHEARED APART AS A 120 KNOT JET MOVES UP THE EAST SIDE OF THE TROUGH INTO THE OHIO VALLEY. A SHORTWAVE CAN ALSO BE SEEN OVER NORTHWEST WISCONSIN... APPROACHING THE GREAT LAKES REGION. A 1000MB SURFACE LOW IS LOCATED OVER SOUTH CENTRAL TENNESSEE AND WILL SLOWLY DEEPEN AS IT TRACKS ACROSS SOUTHEAST OHIO TONIGHT TOWARDS WESTERN PENNSYLVANIA. AS THIS FEATURE PASSES TO OUR SOUTHEAST TONIGHT...THE MAIN FORECAST CONCERNS REVOLVE ABOUT TIMING A TRANSITION TO SNOW AND IF SNOW WILL BE ABLE TO ACCUMULATE GIVEN THE WARM AIR THAT HAS BEEN IN PLACE FOR LATE DECEMBER.

NAM AND GFS ARE IN GOOD AGREEMENT WITH THE LARGE SCALE FEATURES WITH A SLIGHT TREND(50-80MILES) TOWARDS THE WEST SINCE THE 00Z/25 RUN. CONFIDENCE IN THIS TRACK IS FAIRLY GOOD BUT WILL NEED TO MONITOR FOR A CONTINUED TREND TOWARDS THE WEST OVERNIGHT. RAIN WILL INCREASE THIS EVENING AS MID LEVEL DEFORMATION LIFTS NORTH INTO THE AREA. FRONTOGENETICAL FORCING IS ALSO PROGGED TO INCREASE WITH A GOOD BAND FOCUSED IN THE 650-700MB LAYER ACROSS WESTERN LAKE ERIE AND NORTHWEST OHIO. THIS IS WHERE THE STRONGEST PRECIPITATION WILL BE LOCATED OVERNIGHT WITH AROUND A HALF INCH OF QPF POSSIBLE. AT THIS TIME...MODELS INDICATE THIS FEATURE WILL REMAIN JUST EAST OF OUR COUNTIES...BUT ANY FURTHER WESTWARD TREND OF THE MODELS WOULD BE A CONCERN. PRECIPITATION OVER SOUTHEAST MICHIGAN WILL BE DRIVEN MORE BY MID LEVEL DEFORMATION WITH SOME LARGER SCALE SUPPORT FROM A COUPLED JET AND GOOD UPPER LEVEL DIVERGENCE.

MODELS DID NOT INITIALIZE LOW LEVEL TEMPERATURES OR MOISTURE WELL ACROSS OHIO/PENNSYLVANIA AND SOUTHERN LOWER MICHIGAN. 12Z RAOBS SHOWED A LAYER OF WARM AIR OF 6-7C FROM 925-850MB AND MODELS WERE GENERALLY 3-4C TOO COOL. WITHIN THIS LAYER...MODELS WERE ALSO NOT DRY ENOUGH WITH RAOBS SHOWING DEWPOINT DEPRESSIONS OF 20-30C. 1605Z FSLACARS SOUNDING OUT OF DTW SHOWED THIS WARM LAYER WELL WITH TEMPS AT 900MB OF 7C. AS PRECIPITATION BEGINS...WE SHOULD SEE THE COLUMN COOL FIRST AT THE ONSET OF PRECIPITATION...THEN DUE TO MELTING AS PRECIPITATION RATES INCREASE. TIMING THE TRANSITION TO SNOW IS DIFFICULT GIVEN THE INITIALIZATION ERRORS IN CAPTURING THE WARM LAYER AND UNCERTAINTY AS TO HOW WELL WEAK COLD AIR ADVECTION WILL BE ABLE TO OVERCOME THAT LAYER THIS EVENING. LOW LEVEL COLD AIR ADVECTION WILL BE FAIRLY WEAK AS THE SHORTWAVE OVER WISCONSIN GENERALLY PASSES TO OUR NORTH WITH THE STRONGER LOW LEVEL FRONTAL PUSH ORIENTED TOWARDS THE EASTERN GREAT LAKES ON TUESDAY. WILL LEAN TOWARDS A TRANSITION TO SNOW DURING THE LATE EVENING HOURS AS THIS COLDER AIR TRICKLES INTO THE AREA. SURFACE TEMPS ARE GENERALLY NEAR 40 DEGREES RIGHT NOW WITH DEWPOINTS IN THE MID 30S SO IT WILL TAKE A WHILE FOR ANY SNOW TO BE ABLE TO ACCUMULATE. THE EXCEPTION TO THIS WOULD BE IN AREAS THAT SEE HIGHER PRECIP RATES WHERE PRECIPITATION COULD CHANGE OVER TO SNOW TEMPORAIRILY ...THEN BACK TO RAIN. IF PRECIPITATION TRANSITIONS TO SNOW SOONER THEN ACCUMULATIONS MAY NEED TO BE ADJUSTED/INCREASED.

TAKING INTO ACCOUNT WARM GROUND TEMPERATURES AND A WET SNOW TONIGHT...WILL GENERALLY EXPECT TO SEE 1-2 INCHES OF SNOW SOUTH OF I-69 WITH SOME MINOR ACCUMULATIONS TO THE NORTH. SOME LOCALLY HIGHER AMOUNTS WILL BE POSSIBLE...ESPECIALLY ACROSS THE IRISH HILLS WHERE SNOW MAY BE ABLE TO ACCUMULATE BETTER. SOME AREAS...ESPECIALLY WITHIN THE DETROIT HEAT ISLAND...MAY JUST SEE SNOW ON GRASSY AND ELEVATED SURFACES WITH WARM GROUND TEMPERATURES. WILL CONTINUE TO MONITOR THE DEVELOPMENT OF THE GOOD FRONTAL CIRCULATION THAT IS FORECAST TO SET UP JUST SOUTHEAST OF THE AREA AND WILL UPDATE THE FORECAST IF IT LOOKS LIKE THIS FEATURE WILL AFFECT OUR SOUTHEASTERN COUNTIES.

WILL CONTINUE THE SNOW INTO TUESDAY MORNING WITH JUST SOME MINOR ACCUMULATIONS POSSIBLE BEFORE SNOW DIMINISHES FROM THE NORTHWEST.

&&

.LONG TERM...TUESDAY NIGHT THROUGH NEW YEARS DAY

AS THE DEEP UPPER TROUGH MOVES OFF THE EAST COAST ON WEDNESDAY...THE FLOW ACROSS NORTH AMERICA IS AGAIN FORECAST TO TRANSITION TO A SPLIT FLOW REGIME...WITH ANOTHER DEEP UPPER LOW FORECAST TO DEVELOP IN THE SOUTHERN STREAM BY THE END OF THE WEEK. A WEAK NORTHERN STREAM WAVE FORECAST TO MOVE ACROSS THE NORTHERN GREAT LAKES ON WEDNESDAY WILL REINFORCE THE LOW LEVEL COLD AIR ACROSS NORTHERN MICHIGAN. THE AMPLIFYING TROUGH ACROSS THE SOUTHWESTERN US WILL THEN AMPLIFY DOWNSTREAM RIDGING ACROSS THE EASTERN US THURS INTO FRIDAY. A LARGE AREA OF HIGH PRESSURE IS FORECAST TO BUILD ACROSS THE GREAT LAKES THURS INTO FRIDAY. GFS MODEL SOUNDINGS INDICATE QUITE A BIT OF LOW LEVEL DRY AIR. SO DESPITE A GRADUAL MODERATION IN TEMPERATURES THROUGH FRIDAY...NIGHTTIME LOWS MAY DROP WELL INTO THE 20S DEPENDING ON THE EXTENT OF MID AND HIGH LEVEL WARM AIR ADVECTION CLOUDS.

THE 12Z MODEL SUITE ARE ALL IN AGREEMENT IN A DEEP YET PROGRESSIVE UPPER LOW DEVELOPING OVER THE SOUTHERN ROCKIES BY THURSDAY. TIMING OF THIS SYSTEM INTO THE CENTRAL AND EASTERN US WILL BE THE MAIN FORECAST CONCERN IN THE LONG RANGE. THE WAVE THAT IS FORECAST TO AMPLIFY OVER THE WESTERN US IS STILL WELL OUT IN THE PACIFIC. WATER VAPOR IMAGERY SUGGEST A STRONGER SHORT WAVE THAN THE 12Z MODEL INITIALIZATIONS INDICATED...WHICH MAY SIGNAL A STRONGER AND SLOWER SYSTEM. THERE IS STILL SOME LARGE SPREAD IN SOLUTIONS THIS WEEKEND...BUT MAJORITY OF ENSEMBLE MEMBERS BRING THE UPPER LOW INTO THE GREAT LAKES REGION DURING THE WEEKEND. AMPLE WARM AIR AND MOISTURE ADVECTION IN ADVANCE OF THIS SYSTEM WILL BRING ANOTHER ROUND OF RAINFALL TO THE AREA. AS WITH THIS CURRENT SYSTEM...THE MAIN CONCERN WILL BE HOW MUCH COLD AIR ADVECTS INTO THE REGION ON THE BACK SIDE OF THE UPPER LOW.

THE 12Z OPERATIONAL GFS SUPPORTS THE CURRENT FORECAST BY BRINGING ENOUGH COLD AIR IN BEHIND THIS SYSTEM TO ALLOW A MIX OR CHANGE OVER TO SNOW ON SUNDAY. IN ADDITION TO THE UNCERTAINTY WITH RESPECT TO THE SOUTHERN STREAM UPPER LOW...ENSEMBLE MEMBERS SHOW A LOT OF SPREAD WITH A NORTHERN STREAM WAVE. A FEW GFS ENSEMBLE MEMBERS AND THE 00Z ECMWF INDICATE A STRONGER NORTHERN STREAM WAVE WITH SOME PHASING OCCURRING WITH THE SOUTHERN STREAM UPPER LOW AS IT LIFTS INTO THE GREAT LAKES. THE NORTHERN STREAM WAVE WILL HAVE TO BE MONITORED AS THERE IS EXPECTED TO BE A MUCH COLDER AIRMASS RESIDING JUST TO THE NORTH OF THE GREAT LAKES THAN IN THE PAST COUPLE OF WEEKS. IF THIS SYSTEM IS ABLE TO BE AS DEEP AND AS PROGRESSIVE AS MODELS INDICATE...QUITE A BIT OF GULF MOISTURE WILL BE DRAWN INTO THE SYSTEM. OVERALL THE CURRENT FORECAST HAS THIS SCENARIO COVERED WELL GIVEN THE LEVEL OF UNCERTAINTY. THUS THE ONLY MAJOR ADJUSTMENT TO THE FORECAST WILL BE TO BACK OFF ON THE RAIN ON FRIDAY IN ANTICIPATION OF A SLOWER SYSTEM. IN LIGHT OF THE 12Z MODEL SUITE...HAVE ALSO RAISED POPS A BIT THIS WEEKEND.

&&

.PREVIOUS DISCUSSION...ISSUED 105 PM EST MON DEC 25 2006

AVIATION...

LOW PRESSURE OVER NORTHEAST MISSISSIPPI WILL TRACK TO WESTERN PENNSYLVANIA BY TUESDAY MORNING. AS IT DOES SO...PRECIPITATION WILL SPREAD NORTH INTO SOUTHEAST MICHIGAN BY LATE THIS AFTERNOON/EARLY THIS EVENING. MEANWHILE A SHORTWAVE APPROACHING FROM THE NORTHWEST WILL HELP TO ADVECT COLDER AIR OVER THE STATE. RAIN IS EXPECTED TO TRANSITION TO SNOW BY LATE EVENING WITH SOME MODERATE SNOW SHOWERS EXPECTED AT THE DETROIT AREA AIRPORTS. SNOW SHOWERS WILL CONTINUE THROUGH THE NIGHT...THEN TRANSITION TO DRIZZLE OR FLURRIES ON TUESDAY MORNING. WITH GOOD LOW LEVEL MOISTURE ADVECTION...CEILINGS WILL DROP DOWN INTO THE IFR RANGE OVERNIGHT. NORTHERLY WINDS WILL INCREASE AS THE SURFACE LOW TRACKS ACROSS SOUTHEAST OHIO AND WILL REMAIN BREEZY THROUGH THE DAY ON FRIDAY.

&&

&&

.DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT HURON...MIDNIGHT TUESDAY TO 7 AM WEDNESDAY.

SMALL CRAFT ADVISORY...LHZ421...MIDNIGHT TUESDAY TO 1 PM TUESDAY.

SMALL CRAFT ADVISORY...LHZ422...6 AM TUESDAY TO 11 AM TUESDAY.

LAKE ST CLAIR...SMALL CRAFT ADVISORY...LCZ460...6 AM TUESDAY TO 1 PM TUESDAY.

MI WATERS OF LAKE ERIE...SMALL CRAFT ADVISORY...LEZ444...6 AM TUESDAY TO 1 PM TUESDAY.

&&

$$

SHORT TERM...KAHL LONG TERM....CONSIDINE AVIATION...KAHL

YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).

.UPDATE... GOING FORECAST IN GOOD SHAPE. HAVE ADJUSTED SKY GRIDS TO READ MOSTLY SUNNY FOR MOST OF THE CWA. STRATUS DECK IS NOW CLEARING THE SOUTHEAST CORNER OF THE WISCONSIN CWA. WILL HAVE TO WATCH FOR REDEVELOPMENT OF SC BACK INTO FAR EAST /KRPD-KLUN LINE/ ALONG THE WESTERN EDGE OF EXITING CLOUD DECK OVER THE NEXT COUPLE HOURS. PROFILE FROM AIRCRAFT DESCENT INTO EAU SHOWS DECREASING RESIDUAL MOIST LAYER AROUND 2 KFT WHICH MAY HOLD ON LONG ENOUGH TO REDEVELOP A FEW ADDITIONAL CLOUDS...BUT EXPECT THAT DRYING WILL CONTINUE TO OCCUR. ..MDB..

&&

.PREV DISCUSSION... /ISSUED 540 AM CST MON DEC 25 2006/

DISCUSSION...

PREV DISCUSSION... /ISSUED 402 AM CST MON DEC 25 2006/ THE LATEST SATELLITE IMAGERY OFF THE 11-3.9 MICRON SHOWED A LEANING EDGE OF LOW CLOUDS OVER OUR FAR NORTHERN PORTION OF THE FORECAST AREA. CLOUDS APPEAR TO MORE EXTENSIVE OVER NORTHERN MN. THE CLOUDS ARE EXPECTED TO ROTATE SOUTHEAST ACROSS THE NORTHEAST HALF OF THE CWA TODAY...THEN LIFT NORTHEAST OVR THE GREAT LAKES THIS EVENING. TEMPERATURES AGAIN ARE STARTING OFF RATHER MILD FOR LATE DECEMBER. TEMP DURG THE BALANCE OF THE TODAY ARE EXPECTED TO HOLD NEARLY STEADY OR RISE A FEW DEGREES FROM THE MORNING LOWS.

IN THE MEDIUM RANGE...UPPER RIDGE TRANSLATE OVER THE UPPER MIDWEST OVER THE NEXT FEW DAYS. IT SHOULD BE A DRY AND MILD PERIOD THRU THURSDAY MRNG. THE MAIN CHALLENGE THIS PERIOD...ARE TEMPERATURES... WITH THE LACK OF APPRECIABLE SNOW COVER OVER NORTH AMERICA...GUIDANCE TEMPS HAVE BEEN LEANING TOWARD CLIMO ...SO HAVE OPTED TO RAISE TEMPS A BIT...STILL MAY NOT HAVE TEMP WARM ENOUGH. LONG TERM MODELS ARE FOCUSING ON A SYSTEM DEVELOPING OVER THE SOUTHERN PLAINS LATE IN THE WEEK. ALOT OF DIFFERENCES IN THE MODELS. PREFER THE EUROPEAN MODEL. NORTHERN SHORT WAVE TROUGH MOVING OVER THE WESTERN GREAT LAKES...SHOULD HELP PRODUCE SOME LIGHT PRECIPITATION THURSDAY AND FRIDAY. NOT MUCH CONFIDENCE IN THE MODELS.

AVIATION...UPDATE FOR 12Z TAF CYCLE CONCERN FOR TAFS ARE MVFR CIGS WITH STRATUS/STRATOCU MOVING AND EVOLVING SOUTHEAST OVER EASTERN MN AND WESTERN WI. LOW CLOUDS ARE EMBEDDED IN CYCLONIC FLOW AROUND LOW PRESSURE OVER EASTERN LAKE SUPERIOR. LOW LEVEL LAPSE RATES AND LOWER MOISTURE PROFILES FAVOR CLOUDS TO BECOME MORE ROBUST THROUGH 16Z ESPECIALLY ALONG SECONDARY LOW LEVEL COLD AIR ADVECTION MAXIMUM CURRENTLY MOVING OVER ARROWHEAD. BUT AS HIGH PRESSURE BUILDS IN FROM THE WEST CLOUD PROSPECT WILL DIMINISH FROM WEST TO EAST THROUGH AFTERNOON. SO AT STC AND MSP MVFR POTENTIAL EXISTS THROUGH THE MORNING AND IN WESTERN WI INTO LATE AFTERNOON. SURFACE GRADIENT AND STACKING OF NORTHWEST FLOW IN THE LOWER TROP PROFILE DOES OFFER POTENTIAL OF GUSTS TO OVER 15KTS THROUGH MID AFTERNOON AT THESE EASTERN TAF SITES AS WELL. DIRECTION SHOULD REMAIN SOLID FROM THE NORTHWEST. RIDGE INFRINGEMENT ON SOUTHERN MN WILL LEAD TO RAPIDLY WEAKENING FLOW DURING THE EVE.

MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE.

&&

.MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. &&

$$

.AVIATION(18Z-18Z)... RAIN SPREADING ACROSS MUCH OF NORTHERN OHIO ALREADY. THERE COULD BE A BREAK IN THE STEADY RAIN AS EAST DOWNSLOPE WIND AND DRY SLOT PUSH NORTHWARD WITH SURFACE LOW LATE THIS AFTERNOON AND THIS EVENING BUT ADDITIONAL RAIN WILL RETURN FROM THE SOUTH THIS EVENING AND TONIGHT AND AS THE WIND COMES AROUND FROM THE NNE CEILINGS AND VSBY WILL ALMOST CERTAINLY DROP TO IFR. THUNDER NOT OUT OF THE QUESTION AT CAK OR YNG AS SFC LOW PASSES NEARBY TNGT BUT WILL NOT INCLUDE IN THE TAF FOR NOW. COLDER AIR WILL FILTER IN FROM THE NNW AND THE RAIN WILL CHANGE TO SNOW FIRST AT TOL AND FDY LATE TNGT AND THEN SPREADING EAST BUT NOT UNTIL TUE MORN AT YNG. BACK EDGE OF DECENT PCPN WILL BEING TO PULL OUT MON MORNING AND SNOW WILL TAPER OFF AT TOL AND FDY.

&&

.SHORT TERM UPDATE(THIS AFTERNOON)... RAIN BEGINNING TO MOVE INTO THE SOUTHERN PORTION OF FORECAST AREA. THE RAIN WILL CONTINUE TO MOVE NORTHEAST..AND WAS RUNNING INTO SOME DRIER AIR...HOWEVER THE DRY AIR WILL GIVE WAY TO INCREASING MOIST AIR THRU THE AFTERNOON. MORNING TAMDAR DATA INDICATED MOISTURE WAS WAS AROUND 10,000 TO 11,000 FEET. THE FREEZING LVL AROUND 9,000 FEET. SO PRECIPITATION WILL BE RAIN FOR THE AFTERNOON. THE ONLY CHANGES TO THE FORECAST WILL BE SOME WORDING. HIGHS RANGING FROM THE LOW TO MID 40S.

&&

.SHORT TERM(TODAY THROUGH TUESDAY NIGHT)... WELL...AFTER SHOWING SIG DIFFS THE PAST COUPLE OF DAY...THE GFS AND NAM HAVE FINALLY IN AGREEMENT WITH HANDLING OF MAIN FEATURES THIS PERIOD. UNFORTUNATELY STILL SOME QUESTIONS AS TO TIMING OF PRECIP TRANSITION FROM RAIN TO SNOW. FIRST THINGS FIRST HOWEVER...REGIONAL 88D LOOP CONTS TO SHOW PRECIP SPREADING N QUICKLY AHEAD OF SFC LOW. BOTH NAM AND GFS APPEAR A LITTLE SLOW WITH MOVEMENT OF THIS PRECIP SHIELD AND HAVE ADJUSTED FORECAST TO ALLOW PRECIP TO ARRIVE AN HOUR OR TWO EARLIER THAN PREVIOUS FORECAST PACKAGE. SFC LOW TO MOV TO NEAR KBNA BY 00Z AND TO NEAR KPIT BY 12Z TUE. PRECIP WILL CONT UNABATED WHILE THIS HAPPENS. NOT MUCH COLD AIR TO THE N OF AREA TO BE ADVECTED IN SO TRANSITION TO SNOW WILL BE SLOW. IN FACT...BOTH GFS AND NAM KEEP 1000 TO 850MB THICKNESS ABOVE 1300M TILL AROUND 12Z TUE. AT THE SAME TIME SURFACE WET BULB TEMPS FORECAST TO REMAIN CLOSE TO 35 DEG F SO FREEZING PRECIP UNLIKELY. BOTH MODELS SHOWING AREA OF SIG UVV LATE TONIGHT BUT NOT SURE IF COLUMN WILL COOL FAST ENUF FOR CHANGE TO SNOW. BUFKIT SOUNDINGS REALLY ONLY SHOWING A COUPLE HOUR PERIOD OF STRONG UVV IN THE FAVORED SNOW GROWTH REGION. IF TEMPS AT SFC AREN/T COLD ENUF DURING THE PERIOD FOR SNOW...STORM TOTAL ACCUMS WILL BE GREATLY REDUCED. GIVEN UNCERTAINITY WILL KEEP FORECAST SIMILAR TO PREVIOUS PACKAGE WITH TRANSITION OCCURING LATE TONIGHT WHICH SEEM REASONABLE GIVEN NEW GUIDANCE. ACCUMS THRU DAYBREAK TUE WILL BE SLIGHT. 850 MB TEMPS FINALLY DIP TO NEG 4 TO NEG 5 TUE AM AND THIS WILL FINALLY GET RID OF ANY REMAINING LIQUID PRECIP. ERN AREAS COULD GET A FEW INCHES OF SNOW TUE BUT WOULD BE SURPRISED TO SEE MUCH MORE THAN AN INCH TOTAL WRN AREAS. LOW WILL QUICKLY RACE OFF TO THE NE ON TUE AND DRY AIR WILL COME IN QUICK BEHIND. WILL KEEP CHC WORDING MOST OF AREA TUE WITH LIKELY IN THE SNOWBELT AS 850 MB TEMPS DIP TO AROUND NEG 850. WILL AGAIN USE A BLEND OF GUID TEMPS.

HAPPY HOLIDAYS FROM THE STAFF HERE AT WFO CLE.

&&

.LONG TERM(WEDNESDAY THROUGH SUNDAY)... ACTIVE WEATHER PATTERN SETTING UP FOR THE END OF THE YEAR AND FROM THE LOOKS OF IT...2006 IS NOT GIVING UP WITHOUT A FIGHT.

DELTA LOW THAT TRACKS UP TO THE NORTHEAST OVER THE AREA IS FORECAST TO CONTINUE MOVING NORTHEAST TO THE CANADIAN MARITIMES BY TUESDAY NIGHT. LOW PRESSURE SYSTEM WILL GRADUALLY PULL PRECIPITATION OUT OF THE AREA BY WEDNESDAY AS HIGH PRESSURE QUICKLY BUILDS NORTHEAST INTO THE AREA BY WEDNESDAY NIGHT. FAIR WEATHER WILL CONTINUE THROUGH THURSDAY MORNING AND THEN GIVE WAY TO A WARM FRONT THAT WILL MOVE INTO THE AREA DURING THE DAY THURSDAY. I WILL BRING IN A CHANCE FOR SOME SHOWERS THURSDAY AFTERNOON IN THE WESTERN THIRD OF THE FORECAST AREA WITH THE WARM FRONT. THEN...THURSDAY NIGHT I WILL LIFT THE FRONT NORTHEAST ACROSS THE AREA WITH A CONTINUE CHANCE OF SNOW SHOWERS OVER ALL AREAS EXCEPT NORTHWEST PENNSYLVANIA. THE PRECIPITATION WILL TAPER OFF FROM THE SOUTHWEST IN THE WAKE OF THE FRONT BUT WILL LIFT INTO NORTHEAST OHIO AND NORTHWEST PENNSYLVANIA BY FRIDAY MORNING.

UPPER LEVEL LOW PRESSURE SYSTEM PROGGED TO TRACK SLOWLY EAST ACROSS THE SOUTHERN TIER STATES THURSDAY INTO SATURDAY WILL FORCE A SURFACE LOW TO DEVELOP OVER THE TEXAS GULF COAST AND THEN ROTATE NORTHEAST ON THE EAST SIDE OF THE UPPER LEVEL LOW PRESSURE SYSTEM TOWARD THE FORECAST AREA. THIS SCENARIO COULD SET UP THE AREA FOR ANOTHER POTENTIAL SNOW STORM FOR THE END OF THE YEAR. THIS SITUATION SEEMS REASONABLE AS IDEAL PLACEMENT OF COLD HIGH PRESSURE IS PROGGED TO BE SITUATED OVER SOUTHERN QUEBEC PUMPING COLD AIR INTO THE REGION. THIS IS ONE OF THOSE SITUATIONS WHERE THE PRECIPITATION SLASH NO PRECIPITATION LINE COULD BISECT THE FORECAST AREA. BUT FOR NOW WILL KEEP ENTIRE AREA IN A CHANCE FOR SNOW SHOWERS SATURDAY NIGHT AND THEN BEGIN TO PULL THE PRECIPITATION OUT OF THE WEST ON SUNDAY.

ENSEMBLE AND GFS TEMPERATURES RELATIVELY CLOSE THROUGH THIS PERIOD SO STAYED PRETTY CLOSE TO THEM FOR NOW. &&

.CLE WATCHES/WARNINGS/ADVISORIES... OH...NONE. PA...NONE.

&&

$$

SHORT TERM...KUBINA LONG TERM...LOMBARDY AVIATION...KOSARIK

.SHORT TERM...TONIGHT THROUGH TUESDAY...QUIET PERIOD CONTINUES AS UPPER TROF OVER STATE SHIFTS EAST AND RIDGE BUILDS IN. SURFACE LOW OVER TENNESSEE WILL LIFT OUT TO THE NORTHEAST...WITH A SLOW DECREASE IN CLOUDS EXPECTED INTO TUE MORNING. LOW CLOUDS OVER AREA TO BE ENHANCED OFF LAKE WITH NORTHERLY FLOW...SO HAVE HELD ON TO MVFR CIGS IN RHI AND GRB LONGER TONIGHT. SAT IMAGERY BEGINNING TO SHOW SOME LAKE CLOUDS ORGANIZING OVER LAKE SUPERIOR. WILL CONTINUE TO CARRY SMALL CHANCE POPS OVER FAR NORTH CENTRAL...THOUGH BACKED OFF SOME ESPECIALLY FOR TUESDAY AS MODEL SOUNDINGS/SUPPORTED BY AFTERNOON TAMDAR SOUNDINGS/SHOW INVERSION DROPPING...BELOW 3K AFTER MIDNIGHT TONIGHT WITH SURFACE HIGH BUILDING IN. WITH MORE CLOUDS AND GRADIENT FOR MOST OF NIGHT WILL TREND TOWARDS WARMER MOS FOR LOWS TONIGHT. MID AND HIGH CLOUDS OVER DAKOTAS PUSHING EAST THIS AFTERNOON...ASSOCIATED WITH NEXT WAVE SHIFTING EAST ALONG U.S./CANADIAN BORDER...SO PARTLY TO MOSTLY CLOUDY SKIES EXPECTED FOR TUESDAY.

.LONG TERM...TUESDAY NIGHT THROUGH NEXT SUNDAY.

WEAK HI PRESSURE WILL DRIFT EAST ACROSS THE FORECAST AREA TUESDAY NIGHT AND WEDNESDAY WITH CONTINUED QUIET WEATHER WITH ABOVE NORMAL TEMPERATURES.

AS ADVERTISED PREVIOUSLY...MAIN FOCUS FOR LATE IN THE WEEK AND INTO THE UPCOMING WEEKEND WILL BE RATHER IMPRESSIVE STORM SYSTEM DEVELOPING OVER THE SOUTHERN ROCKIES THAT WILL EVENTUALLY EJECT INTO THE PLAINS. MODELS GENERALLY SIMILAR WITH UPPER LOW PLACEMENT IN THE VICINITY OF SE COLORADO BY 00Z FRIDAY...WITH STRENGTHENING SURFACE LOW PRESSURE OVER MISSOURI BY SATURDAY MORNING. AS LOW TO MID-LEVEL SOUTHERLY FLOW INTENSIFIES AHEAD OF THE SYSTEM...WAA WILL INCREASE RAPIDLY OVER THE UPPER MIDWEST ON THURSDAY. MODELS STILL HINTING AT INITIAL LIGHT PRECIPITATION BAND TO PUSH NORTH ACROSS THE FORECAST AREA AS EARLY AS THURSDAY AFTERNOON. COULD BE SOME LIGHT MIXED PRECIP WITH THIS INITIAL MOISTURE SURGE...BUT OPTED TO CONTIHUE DRY FORECAST FOR NOW.

ALTHOUGH STILL MUCH UNCERTAINTY AS TO THE DETAILS SYSTEM EVOLUTION... MAIN SURGE OF PRECIPITATION LOOKS TO BEGIN LATE ON FRIDAY AS SURFACE LOW DEEPENS OVER THE CENTRAL MISSISSIPPI VALLEY. GFS CURRENTLY THE STRONGEST AND SLOWEST WITH THIS SYSTEM OVER THE WEEKEND AND SUGGESTS A MORE PROLONGED PRECIPITATION EVENT. AS PER PREVIOUS FORECAST...WILL CONTINUE MENTION OF MIXED BAG OF SNOW...SLEET...FREEZING RAIN...AND RAIN FOR NOW...BUT CERTAINLY POTENTIAL FOR BAND OF HEAVY SNOW ESPECIALLY WEST OF THE FOX VALLEY. BASED PRIMARILY ON THE GFS...DECIDED TO NUDGE SOMEWHAT HIGHER POPS FURTHER INTO THE UPCOMING WEEKEND. CERTAINLY POTENTIAL FOR SIGNIFICANT SYSTEM TO AFFECT THE AREA OVER THE UPCOMING HOLIDAY WEEKEND. SUBSEQUENT SHIFTS WILL PROVIDE MORE DETAILS AS THEY BECOME MORE CLEAR. &&

.GRB WATCHES/WARNINGS/ADVISORIES... NONE. &&

$$ TE/EB WEATHER.GOV/GREENBAY