Forecast Discussions mentioning "ACARS", "MDCRS", or "AIRCRAFT" received at FSL on 02/21/03

AVIATION DISCUSSION FOR 18Z TAFS A LARGE ANTICYCLONE LIES OVER OHIO AND EXTENDS WEST TO KANSAS. THIS WILL PROVIDE SOUTHWEST WINDS AT 15 TO 25 KNOTS THROUGH 0200 UTC. THIS HIGH IS FORECASTEDS TO MOVE EAST VERY SLOWLY THROUGH 18 UTC FRIDAY. SATELLITE AND SURFACE OBSERVATIONS SHOW HIGH CLOUDS. THE ACARS SOUNDING SHOW WINDS FROM THE SOUTHWEST THROUGH 740 MB.

WHW

PUBLIC DISCUSSION FOR 4 AM ZONES/GRIDS

FORECAST CONCERNS FOCUS ON TWO SYSTEMS THIS WEEKEND. HIGH PRESSURE IN CONTROL IN THE SHORTTERM PROVIDING WARMER AND SUNNY THURSDAY. WITH LOWS STARTING IN THE MID 20S...SOUTHERLY WINDS AND LOTS OF SUN SHOULD EASILY SEE MID 40S TODAY. HIGH MOVES EAST TONIGHT. FRIDAY ALSO LOOKING WARM BUT SHOULD SEE INCREASE IN HIGH/MID LEVEL CLOUDS. WINDS BECOME NORTHEASTERLY AFTERNOON/EVENING AND THE SOONER THAT HAPPENS...THE LOWER HIGHS ACROSS EASTERN AREAS.

SFC LOW THAT DEVELOPS OVER THE SOUTHERN PLAINS FRIDAY NOW MOVING A LITTLE FARTHER NORTH AND WEST THAN PREVIOUS RUNS. CANADIAN LEADING THIS TREND BRINGING LOW ACROSS IN/OH BY 00Z SUN. GFS STILL ACROSS TN/KY SATURDAY BUT PRECIP SHIELD AFFECTING SE FA. SLOWER MOVEMENT AND DEVELOPMENT INITIALLY WITH SFC LOW WILL PROBABLY HELP DIGGING UPPER LEVEL TROF TO CATCH UP AND PULL SYSTEM FARTHER NORTHWEST. HOW MUCH FARTHER...STILL UNCERTAIN SO WILL BRING CHANCE POPS ACROSS SE FA FRI NIGHT AND ENTIRE CWA SAT.

NEXT SYSTEM MOVES SOUTHEAST ACROSS SOUTHERN PLAINS THEN TAKES SIMILAR SWING NORTHEAST AS FIRST SYSTEM. STRENGTH AND LOCATION STILL UNCERTAIN BUT WORTHY OF CHANCE OF SNOW SUNDAY ENDING MONDAY. EXTENT OF CLOUDS PRECIP AND NORTHEAST WINDS OFF LAKE MI TO MAKE FOR SOME TOUGH TEMP FORECASTS. TRENDING WARMER PROBABLY A BETTER BET UNTIL MONDAY WHEN SYSTEM PULLS EAST AND HIGH BUILDS ACROSS PLAINS.

.CHI...NONE.

CMS



.SYNOPSIS...A WARM FRONT WILL SPREAD PRECIPITATION INTO WESTERN WASHINGTON TODAY AND MUCH NEEDED SNOW INTO THE MOUNTAINS. ANOTHER WEATHER SYSTEM WILL ARRIVE FRIDAY...MAINTAINING SHOWERS...WITH MORE SNOW IN THE MOUNTAINS. HIGHER PRESSURE ALOFT IS EXPECTED TO DEVELOP SATURDAY AND HOLD INTO EARLY NEXT WEEK FOR A DRYING TREND.

.DISCUSSION...SURFACE OBS SHOW WARM FRONT MOVED THROUGH BUOY 206 OFF VANCOUVER ISLAND AT 15Z. FIRST VISIBLE IMAGES SHOW FRONT EXTENDING BACK TO THE SOUTHWEST. MARINE OBS OVER THE COASTAL WATERS NOT INDICATING FRONTAL PASSAGE. CURRENT TIMING BRINGING FRONT THROUGH THE COAST AROUND 20Z...KSEA 22Z AND INTO THE CASCADES AFTER 00Z. ACARS SOUNDINGS SHOW SW WINDS AT THE LOWER LEVELS WITH THE WINDS BECOMING NORTHWESTERLY AROUND 8000 FEET LEADING TO A WEAK RAINSHADOW EFFECT FOR THE METRO AREA. THIS WILL GRADUALLY FILL IN AS THE FRONT GETS CLOSER. GOOD OROGRAPHICS RIGHT BEHIND THE FRONT BUT MODELS BACKING OFF A BIT ON THE OROGRAPHICS FOR FRIDAY MORNING WITH THE UPPER LEVEL WINDS TAPERING OFF AHEAD OF THE STRONG TROUGH THAT MOVES THROUGH THE AREA FRIDAY AFTERNOON. GOOD CONVERGENCE ZONE PATTERN BEHIND THE TROUGH FOR FRIDAY NIGHT FOR THE POSSIBILITY AGAIN OF SIGNIFICANT SNOWS IN THE CASCADES. UPPER LEVEL RIDGE BUILDING OFFSHORE WITH UPPER LEVEL FLOW SPLITTING BEGINNING SATURDAY. FORECASTS IN GOOD SHAPE NO UPDATE. felton

UIL +89 SEA 976 OLM 977

.KSEW...SMALL CRAFT ADVISORY ALL WATERS. HEAVY SNOW WARNING CASCADES.

.KATX...VCP21/CSR21...OPERATIONAL.

$$



FORECAST CHALLENGES ARE PRECIP CHANCES AND TEMPS NEARLY ALL PERIODS.

00Z UPPER AIR ANALYSIS AGAIN SHOWING MAIN JET ENERGY DIVING SOUTH ALONG THE WEST COAST THEN RETURNING NORTHEAST THROUGH THE OHIO VALLEY. 130KT CORE SAMPLED BY ACARS WAS NEARING THE PACIFIC NORTHWEST COAST. UPPER LOW WAS JUST SOUTH OF ARIZONA WITH SIGNIFICANT FALLS RELEGATED TO SOUTHERN TEXAS. 700MB LEVEL SHOWED SOME MOISTURE MAKING ITS WAY INTO KANSAS FROM THE SOUTHWEST SYSTEM. ARCTIC COLD FRONT HAD SUNK SOUTH THROUGH MUCH OF NORTH DAKOTA WITH OLD FRONTAL BOUNDARY FROM SOUTH TEXAS INTO KENTUCKY. 06Z SURFACE MAP HAD THE ARCTIC FROM JUST SHY OF NORTHEAST NEBRASKA AND SATELLITE IMAGERY INDICATING LOTS OF LOW CLOUDS IN ITS WAKE.

MEXICO SYSTEM WILL MOVE ACROSS SOUTHERN TEXAS TODAY WITH DECENT LIFT STAYING TO THE SOUTH WITH THE OLD BOUNDARY. SOME MID CLOUDS ALONG WITH CIRRUS ARE EXPECTED HOWEVER THERE SHOULD STILL BE ENOUGH SUNSHINE TO GIVE HIGHS IN THE MID 50S. SURFACE LOW WITH THE SOUTHERN SYSTEM MOVES INTO THE OHIO VALLEY TONIGHT HELPING TO BRING THE COLD FRONT FARTHER SOUTH. LOW CLOUDS LIKELY TO FOLLOW BEHIND. WILL CUT GUIDANCE A LITTLE. CYCLOGENESIS BEGINS OVER EASTERN COLORADO SATURDAY AS A SHORTWAVE TROF EVIDENT ON WATER VAPOR LOOP THIS MORNING CROSSES THE ROCKIES. THIS SHOULD HOLD UP THE FRONT OVER KANSAS AND ALLOW SOME BURN OFF OF THE LOW CLOUDS. WILL KEEP HIGHS IN THE LOW TO MID 40S BANKING ON A LITTLE SUNSHINE.

SHORTWAVE INTENSIFIES QUICKLY AS IT ENTERS THE PLAINS SATURDAY NIGHT AS THE SURFACE LOW PUSHES INTO OKLAHOMA. STRONG LAYER Q VECTOR CONVERGENCE AND ISENTROPIC LIFT ABOVE THE FRONT DEVELOP OVERNIGHT WITH MID LEVELS QUICKLY SATURATING. MAY BE A BRIEF WINDOW FOR SOME RAIN IF THE PRECIP DEVELOPS QUICKLY ENOUGH BUT WILL COUNT ON SOME COOLING WITH THE SATURATION TO ALLOW ONLY SNOW TO FALL. MODEL SOLUTIONS CONTINUE TO BE IN MARKEDLY GOOD AGREEMENT WITH THE PLACEMENT OF THE SNOWFALL THROUGH THE EVENT ALTHOUGH THEY ARE A TOUCH SLOWER THAN YESTERDAYS RUNS. SEE LITTLE REASON TO ALTER GOING HIGH POPS MUCH SUNDAY ALTHOUGH WILL TRIM THEM A BIT IN THE FAR NORTHEAST ZONES WHERE THEY ARE FARTHER FROM THE FORCING. ALTHOUGH LOTS OF DYNAMICS SHOULD BE IN PLACE MODEL QPF AMOUNTS SEEM A BIT HIGH. WILL KEEP CURRENT HWO WORDING FAIRLY SIMILAR IN TODAYS ISSUANCE PER HPCS MENTIONING OF LOWER QPF AMOUNTS FROM ENSEMBLE MEMBERS. MORNING HIGH TEMPS ARE LIKELY SUNDAY AS THE COLD AIR SURGES THROUGH.

WILL KEEP SMALL POPS GOING SUNDAY NIGHT GIVEN THE SLIGHT SLOWING TREND. PLAN TO RAISE SUNDAY NIGHT LOWS A LITTLE GIVEN RESIDUAL CLOUD COVER AND DECENT NORTHERLY FLOW. MEDIUM RANGE MODELS HAVE COME INTO MUCH BETTER AGREEMENT OVER THE PAST FEW DAYS AND DAY 5 MODEL SKILL SCORES HAVE RISEN. WESTERN CONUS TROF TO DEVELOP AND BRING MORE OPPORTUNITIES FOR PRECIPITATION. COLD AIR LIKELY TO BE HARD TO GET RID OF UNTIL AT LEAST MID WEEK AND WILL KEEP ALL PRECIP IN FORM OF SNOW FOR NOW.

.TOP...NONE.

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