Forecast Discussions mentioning "ACARS", "MDCRS", "AIRCRAFT" or "AMDAR" received at FSL on 01/15/04

.AVIATION DISCUSSION FOR 12 UTC TAFS

WILL USE THE GFS MODEL FOR THE MOVEMENT OF THE CYCLONE IN WESTERN WISCONSIN. THE 3 HOUR ISSALOBARS SHOW -8 MB OVER CENTRAL WISCONSIN AND 700 MB PROFILER WIND WAS 50 KNOTS AT 11 UTC. THE WATER VAPOR LOOP SHOWS A STRONG CIRCULATION MOVING FROM NORTHERN MINNESOTA INTO NORTHERN WISCONSIN. THE LOCAL WORKSTATION ETA MODEL SHOWS A LARGE TEMPERATURE GRADIENT MOVING INTO NORTHERN ILLINOIS BY 18 UTC. THE COLD AIR AND PRECIPITATION WILL COINCIDE TO MAKE THE PRECIPITATION TYPE ALL SNOW. WILL FORECAST LIGHT SNOW FOR THE AIRPORTS STARTING AT 18 UTC. THIS IS AN INTENSE CYCLONE. WILL RAISE THE WIND TO NORTHWEST AT 23 KNOTS GUST TO 30 KNOTS. BECAUSE OF THE FAST MOVEMENT EASTWARD OF THE LOW THE WIND WILL DIMINISH QUICKLY TONIGHT. ACARS SOUNDINGS AT ORD ARE VERY DRY ABOVE 900 MB. THE BUFKIT SOUNDING FORCAST SHOWS THE AIR BECOME MORE HUMID WITH NEAR SATURATION UP TO 5000 FT. THAT IS WHEN THE SNOW WILL BE FALLING. WILL END THE SNOW AROUND 21 UTC AS THE LOW MOVES INTO INDIANA AND SINKING AIR MOVES INTO THE REGION. WHW

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.MID MORNING DISCUSSION GRIDS/ZONES:

SURFACE LOW JUST NW OF MKE AT 10AM CONTG TO MOVE SE ABOUT 45-50MPH AND WILL TRACK INTO SW LOWER MICH BY 2PM OR SO. WELL DEFINED FALL/RISE PRESSURE COUPLET WITH THIS SYSTEM AND EXPECT WINDS TO INCREASE ACROSS FA THIS AFTERNOON AS THEY SHIFT TO W THEN NW. TEMPS ABOUT PEAKED IN MID 30S NOW AND WILL HOLD THERE FOR A FEW HRS BEFORE FALLING OFF LATER THIS AFTERNOON. WINDS HAVE GUSTED TO >40MPH OVER FEW SPOTS IN EASTERN IOWA THIS MORNING AND SOME GUSTS TO 35-40 MPH ARE A GOOD BET FROM MID AFTERNOON TO AROUND 9PM THIS EVE. STRONGEST GUSTS MAY SLIP THROUGH SRN FA TOWARD PIA REGION. SUBIDING WINDS DURING THE NIGHT WITH COLDER TEMPS PER GOING FCST. ACTIVE PATTERN BUT NOTHING REALLY SIGNIFICANT SEEN FOR REST OF WEEK. NO CHANGES NEED TO CURRENT FCST ALTHOUGH GRIDS MAY BE TWEEKED A LITTLE. KML &&

.LOT...WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LK MI...SMALL CRFT ADVSRY IL/IND SHORES THIS AFTN. GL WRNG S HALF LK MI LATE THIS AFTN/TNGT.

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.SYNOPSIS...A LOW PRESSURE TROUGH PASSING BY TO THE WEST WILL BRING SOME HIGH CLOUDS AND COOLING TODAY. A COASTAL EDDY WILL BRING A RETURN OF NIGHT AND MORNING COASTAL LOW CLOUDS INTO SATURDAY MORNING. FAIR DRY WEATHER FOR THE WEEKEND UNDER WEAK HIGH PRESSURE. A TROUGH OF LOW PRESSURE WILL DEVELOP OVER THE WEST EARLY NEXT WEEK BRING COOLER AND BREEZY WEATHER WITH A SLIGHT CHANCE OF PRECIPITATION. SURF IS EXPECTED TO BUILD ALONG THE COAST TONIGHT AND FRIDAY WITH ANOTHER ROUND OF HIGHER SURF FOR SUNDAY AND SUNDAY NIGHT.

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

SHORTWAVE WL PASS BY TO THE WEST TODAY ON ITS WAY TO CNTRL AND SRN BAJA TONIGHT. SATELLITE IMAGERY SHOWS THE ASSOCD MID AND HIGH CLOUDS OVR THE SRN CA BIGHT SPREADING INLAND ACROSS SW CA. WK CSTL EDDY IS DEVELOPING...BUT STRATUS IS MINIMAL SO FAR. SOME PATCHY STRATUS MAY DEVELOP ALG THE CST AROUND DAY BREAK NR THE COAST. RECENT ACARS SOUNDINGS FM ONT STILL SHOW A RELATIVELY STRONG AND SHALLOW MARINE INVERSION WITH WK NELY WINDS ABV THE INVERSION. EVEN THOUGH HEIGHTS WL LOWER TODAY IN RESPONSE TO THE SHORTWAVE GOING BY TO THE WEST... TEMPERATURES IN INLAND AREAS W OF THE MTNS SHOULD BE ABLE TO RISE TO AT LEAST THE MID 70S.

MESOETA MAINTAINS A COASTAL EDDY TONIGHT WITH STRATUS TO SPREAD WELL INTO THE LWR COASTAL VLYS LATE TONIGHT INTO FRI MORNING. MESOETA SHOWS A WKR EDDY FOR FRI NIGHT INTO SAT MORNING. HAVE INTRODUCED LOW CLOUDS FM THE COAST INTO THE LWR COASTAL VLYS FOR FRI NIGHT INTO SAT MORNING...BUT COVERAGE COULD END UP BEING QUITE A BIT LESS THAN FOR TONIGHT INTO FRI MORNING. WEAK HIGH PRESSURE WL HOLD FOR THE WEEKEND WITH FAIR DRY WEATHER AND SOME WARMING.

GFS/ECMWF ARE TRENDING IN A SIMLAR DIRECTION FOR EARLY NEXT WEEK... BUT DIFFER IN THE DETAILS. SOME CHANCE FOR PRECIPITATION FOR SW CA CNTRD AROUND MON AND MONDAY NIGHT. 06Z GFS IS TRENDING AWAY FM THE 00Z GFS AND CLOSER TO THE MORE "INSIDE" TRACK OF THE ECMWF WITH SHORTWAVES FOR MONDAY INTO TUESDAY. THIS WOULD DECR THE PRECIPITATION POSSIBILITIES SOMEWHAT FOR SW CA MON/TUE. THIS WOULD...HOWEVER...STILL BRING SOME COOLING AS WELL AS GUSTY WINDS FOR THE MTNS AND DESERTS.

FOR THE COASTAL WTRS...SURGES OF LARGE LONG PERIOD WEST SWELL WL CONTINUE TO ARRIVE EVERY FEW DAYS. THE NEXT IS EXPECTED TO PEAK TONIGHT AND FRI. ADDITIONAL ROUNDS ARE POSSIBLE SUNDAY AND SUNDAY NIGHT...AND AGAIN WEDNESDAY. REFER TO LAXMWSSGX FOR DETAILS.

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.SGX WATCHES/WARNINGS/ADVISORIES...MARINE WEATHER STATEMENT...SEE LAXMWSSGX.

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.AVIATION... WK CONVERGENCE ALONG EASTERN LAKE MICHIGAN SHORE WITH NW FLOW ALOFT SHOULD CONTINUE SNOW SHOWERS AT SBN MUCH OF THE DAY, BUT GIVEN RECENT ACARS OVER SRN LAKE MICHIGAN SHOWING INVERSION AROUND 3K FEET WITH COLDEST TEMP OF -15C AT 880MB, DOUBT IF THERE WILL ANY SGFNT INTENSIFICATION OF THE LAKE EFFECT. THUS, CONTINUED WITH STATUS QUO FOR TODAY WITH GENERALLY VFR CIGS AND VSBYS AT SBN. STRATO CU DECK OFF LAKE MICHIGAN HAS BEEN MOVG SE TOWARD FWA AND SHOULD MOVE IN BY 14Z AND WITH LOW LEVEL FLOW WKNG SHOULD BE SLOW TO MOVE OUT. AS RIDGE MOVES TO THE EAST TONIGHT AND A WK WARM FRONT LIFTS INTO THE MID MS VALLEY, SOME OVERRUNING SNOW POSSIBLE OVER NRN INDIANA. POPS ONLY IN CHC CATEGORY AS FORCING FAIRLY WK AND LOW LEVELS DRY, SO NO MENTION IN TAFS ATTM, BUT DID LOWER CIGS SOME LATE. && .SHORT TERM TODAY AND TONIGHT...NORTHERLY FLOW RESULTING IN SHORE PARALLEL BAND OF LAKE EFFECT SNOW AFFECTING NWRN COUNTIES ATTM. CALLS TO THE AREA INDICATE ONLY MINOR ACCUMULATION THUS FAR. DESPITE SINGLE BAND STRUCTURE INVERSION IS FAIRLY LOW...ARND 4K FT, AND INSTABILITY NOT THAT GREAT WITH DELTA T'S IN THE UPPER TEENS. CLOUD LEVEL FLOW EXPECTED TO BACK TO NW THIS MORNING CAUSING SINGLE BAND TO MOVE ONSHORE WITH MULTIPLE BANDS THEN DVLPG. MESO ETA AND RUC INDICATING SFC MESO LOW WILL FORM OVER SERN LAKE MICHIGAN THIS MORNING AS FLOW BECOMES LIGHT. THIS SHOULD INTENSIFY LAKE EFFECT A BIT, BUT, BANDS SHOULD BE MOVING AROUND SO EXPECT 1-2 INCHES OF ACCUM IN BERRIEN WITH AROUND AN INCH FOR COUNTIES FARTHER SOUTH AND EAST. MUCH OF THE REST OF THE CWA HAS CLEARED THIS MORNING. WITH FLOW GOING NW, CLOUDS OFF LAKE MICHIGAN SHOULD OVERSPREAD THE AREA THIS MORNING SO CONTINUED WITH MOSTLY CLOUDY FCST. WK LOW LEVEL WAA COMBINED WITH FAIRLY STRONG H7 THTE ADVECTION AND H7 MIXING RATIO INCRSG TO AROUND 3G/KG SUGGESTS KEEPING A CHC OF SNOW IN FCST ACROSS THE CWA TONIGHT. DRY LOW LEVELS WILL NEED TO BE MOISTENED UP BEFORE SNOW CAN REACH THE GROUND. EXPECT WILL BE A NARROW SNOW BAND WILL DEVELOP IN THE WK WAA REGIME BUT LOCATION DIFFICULT TO PINPOINT SO LEFT POPS IN CHC CATEGORY. &&

.LONG TERM... FRIDAY THROUGH WEDNESDAY...SHORTWAVE SHOULD LIFT NE OUT OF THE SOUTHERN PLAINS THIS WEEKEND ACCORDING TO NCEP MODEL CONSENSUS. THE GFS HAS BEEN TRENDING THE SFC LOW NORTH AND DEEPER WHILE THE ETA WAS SHOWING AN EXTREME CHANGE FROM THE 18Z RUN WITH THE NEW 00Z RUN MUCH WEAKER AND MUCH FARTHER SOUTH WITH THE SFC LOW. THE SUBSEQUENT DRAMATIC RUN TO RUN LOW LEVEL THERMAL CHANGES OF THE ETA LED TO A GFS CHOICE. PREFER COLDER GFS TO WARMER ETA...SO HAVE DISCOUNTED ETA SLEET ON BUFKIT AS FAR NORTH AS SBN ON SATURDAY. HAVE INCLUDED A SMALL AREA OF MIXED PRECIPITATION ON SATURDAY IN THE FAR SOUTH AFTER COORDINATION WITH NEIGHBORING OFFICES. THIS AREA SELECTED EXTENDS FROM WHITE COUNTY TO JAY COUNTY. FOR THE FIRST HALF OF NEXT WEEK...THE GFS HAS NOW WITH THE 00Z RUN INDICATED COLDER WEATHER...AND HAS COME IN LINE WITH THE ECMWF THAT HAS BEEN INDICATING ARCTIC AIR OVER THE GREAT LAKES SINCE AT LEAST THE 13/12Z RUN. THE CANADIAN HAS ALSO BEEN TRENDING COLDER AND THE CANADIAN ENSEMBLES HAVE BEEN SHOWN VERY GOOD AGREEMENT AMONG MEMBERS INTO WEDNESDAY EVENING WITH AN UPPER LEVEL TROF OVER THE MIDWEST. THE 15/00Z MEX WAS ALSO SHOWING MUCH COLDER TEMPS WEDNESDAY THAN PREVIOUSLY ADVERTISED...SO FELT THERE WAS ENOUGH CONFIDENCE TO LOWER TEMPS SIGNIFICANTLY EARLY NEXT WEEK. BASIC PATTERN OF CLIPPER TYPE SYSTEMS SHOULD CONTINUE...BUT THE TIMING OF THESE SMALLER SYSTEMS WAS MORE UNCERTAIN BY THE MIDDLE OF NEXT WEEK...SO HAVE KEPT PRECIPITATION IN WEDNESDAY...BUT HAVE INDICATED SNOW WITH THE COLDER AIR. OTHER THAN THE CHANCE FOR SNOW WEDNESDAY...HAVE KEPT CONDITIONS DRY...BUT COULD EASILY BE SOME LAKE EFFECT SNOW SHOWERS AS FCST DELTA T'S RANGE FROM 15 TO 22. &&

.IWX...WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. &&

$$ DJT/MAS