000 FXUS63 KDTX 101158 AFDDTX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 658 AM EST MON JAN 10 2005 .AVIATION... DRIER AIR IS MOVING IN. SOME QUESTION AS TO HOW MUCH SUNSHINE TODAY. DELTA T...LAKE MICHIGAN WATER TEMPERATURE VERSUS 850 MB TEMPERATURE DIFFERENCE...NOT LARGE TODAY...BUT SATELLITE IMAGERY DOES SHOW LAKE EFFECT CLOUDS ACROSS LAKE MICHIGAN BEHIND THE OVERNIGHT COLD FRONT...PLUS MEAN 1000 TO 850 MB WINDS WESTERLY TODAY...SO IN TAFS HAVE GONE NO MORE OPTIMISTIC THAN BROKEN LOW CLOUDS EXCEPT OCCASIONAL MENTION FOR SCATTERED FROM 17Z TO 21Z. NEWEST ETA A LITTLE MORE ROBUST BRINGING LOW MOISTURE BACK INTO SOUTHEAST MI TONIGHT...SO HAVE PUT IN A CHANCE OF VISIBILITY LATE TONIGHT OF 2 MILES IN LIGHT SNOW AND IFR CEILINGS. EXCEPT AS PREVIOUSLY NOTED FOR THE DURATION OF THE TAFS...CEILINGS MVFR AND VISIBILITIES VFR UNTIL OVERALL VISIBILITIES DROP TO 5 MILES ABOUT 07Z WITH MIST/LIGHT FOG. && .PREV DISCUSSION...ISSUED 415 AM EST MONDAY AN ACTIVE AND VERY COMPLICATED PATTERN UNFOLDING ACROSS THE COUNTRY THIS MORNING. NUMERICAL SOLUTIONS HAVE A VARIETY OF SOLUTIONS AS ONE WOULD EXPECT IN THESE FAST ZONAL FLOWS WITH OVERALL SYNOPTIC FORECASTS QUITE DIFFERENT THIS MORNING. OUR MAIN CULPRIT WAS MOVING ASHORE ACROSS SOUTHERN CALIFORNIA...WHERE THEY HAVE HAD ENOUGH RAIN/SNOW...AND EXPECTED TO EJECT INTO THE SOUTHERN PLAINS. HOWEVER, WE ALSO HAVE A STRONG 300MB JET OF 130KTS ACROSS WISCONSIN INTO THE NORTHERN LAKES WHICH MAY ASSIST WITH DIVERGENCE ACROSS THE UPSTREAM I-80 CORRIDOR OF IOWA/NEBRASKA. LATEST SCAN OF THE RADARS SHOW INCREASING REFLECTIVITIES ACROSS THIS REGION BUT NO CONFIRMATION OF PRECIP HITTING THE GROUND AS CEILINGS ARE STILL AROUND 10K FEET AS OF 08Z (IE THE AC DECK). THIS HAS THE LOOK OF INCREASING FGEN FORCING WITH DEPARTING JET TO THE NORTHEAST, APPROACH OF WAVE FROM THE SOUTHWEST AND INCREASING AND VEERING LOW LEVEL JET AS EVIDENT ON THE WIND PROFILERS ACROSS OKLAHOMA/KANSAS. WITH THAT SAID, MODELS CURRENTLY HANDLING THIS SITUATION WELL ARE THE GFS, WRFXX AND TO SOME EXTENT THE CANADIAN. SO WE WILL ATTEMPT TO BLEND THESE MODELS SOMEWHAT WHICH LEADS INTO AN EXTREMELY CHALLENGING FORECAST FOR LATE TONIGHT INTO TUESDAY. FOR TODAY, WE HAVE OUR DEPARTING COLD FRONT WITH NOT MUCH DRIZZLE NOTED ON THE AREA METARS. IN THE WAKE OF THIS FRONT, A DECENT PRESSURE RISE COINCIDING WITH STRONG SUBSIDENCE MOVING ACROSS LAKE MICHIGAN THIS MORNING. IN FACT, LATEST 11U-3.9U IMAGERY SHOWS PLENTY OF BREAKS IN THE STRATUS ACROSS WISCONSIN AND FOLLOWING THE 30AGL CPD/S, THE POTENTIAL EXISTS FOR SOME LIMITED SUNSHINE TODAY SO WE WILL ATTEMPT TO BE OPTIMISTIC WITH SOME SUNSHINE ALTHOUGH 950MB RH DOES REMAIN QUITE SATURATED. OTHERWISE, UPSTREAM HIGH TEMPS ON SUNDAY WERE NOT TOO HIGH (LOW-MID 30S) BUT WE ARE RUNNING A BIT WARMER HERE THIS MORNING AND THEREFORE WOULD HAVE TO FAVOR THE MAV/MET MOS BLEND. TONIGHT IS WHERE IS DOES BECOME INTERESTING. SHORT WAVE ENTERING SOUTHERN CALIFORNIA SHEARS OUT A BIT AS IT APPROACHES THE CENTER OF THE NATION OVERNIGHT. THIS WILL ASSIST WITH INCREASING THE LOW LEVEL JET AND WARM ADVECTION PATTERN UPSTREAM. IN ADDITION, WE WILL BE IN A FAVORABLE ENTRANCE REGION OF DEPARTING 120KT JET WHICH WILL ENHANCE LIFT AND TIGHTEN UP THE THERMAL PROFILES ACROSS THE PLAINS EXTENDING INTO THE SOUTHERN LAKES REGION. WHERE THIS BAROCLINICITY SETS UP WILL DICTATE OUR PRECIP CHANCES OVERNIGHT. THE LATEST WRFXX SUGGESTS THE BEST 850-700MB 2D-FGEN WILL MOVE ACROSS THE SOUTHERN HALF OF THE STATE OVERNIGHT WITH PRECIP DEVELOPING TOWARD MIDNIGHT AND ONWARD. SOUNDINGS HOWEVER CONTINUE TO ADVERTISE SOME DRYING INITIALLY ACROSS THE NORTH BUT CROSS SECTIONS REVEAL A GOOD ENOUGH FGEN CIRCULATION TO WARRANT THE CHANCE OF PRECIP. NOW PRECIP TYPE WILL BE A CHALLENGE AS WELL (ESPECIALLY ON TUESDAY). MOST OF THE CWA WILL LIKELY BE COLD ENOUGH FOR JUST SNOW BUT TOWARD SUNRISE, ENOUGH WARM AIR IN THE 850-900 LAYER SNEAKS INTO LENAWEE AND MONROE COUNTIES FOR THE CHANCE OF SOME FREEZING RAIN. TEMPERATURES OVERNIGHT WILL BE IN THE 20S CWA-WIDE. TUESDAY WILL NEED FURTHER ADJUSTMENTS AS THIS HAS THE POTENTIAL TO BECOME MESSY IN A HURRY...OR JUST A GLANCING SHOT OF PRECIP. INITIAL SHOT OF FGEN FORCING IS EXPECTED TO WEAKEN THROUGH THE MORNING WITH MAIN SURFACE LOW TRACKING ALONG THE OHIO RIVER VALLEY. PREVALENT LOW LEVEL JET AXIS WILL BE POISED UPSTREAM ASSISTING WITH MOISTURE TRANSPORT INTO THE LOWER LAKE REGION. THE GFS SUGGESTS THAT THIS WILL CONTINUE AND BRING PRECIP ALL DAY TO THE REGION. BUT INSTABILITY WILL BE INCREASING WELL TO OUR SOUTH AND IF THIS TAKES OFF, MOISTURE AVAILABILITY WILL BECOME LIMITED LEAVING US WITH A DRIER AFTERNOON. QUICK GLANCE OF THE 06Z ETA IS NOW SUGGESTING THIS IDEA WHICH LEADS TOWARD A LOW CONFIDENCE FORECAST. PRECIP TYPE IS ALSO AN ISSUE WITH OUR CHOICE OF SNOW, SLEET, FREEZING RAIN AND RAIN (NORTH TO SOUTH). WITH THE TREND TOWARD COOLER COLUMN...WE WILL SHADE IN THAT DIRECTION WITH MORE WINTRY MESS. THIS SHOULD HOLD DOWN ACCUMULATIONS BUT STILL CAUSE SOME TRAVEL PROBLEMS ON TUESDAY. THEN AS ANOTHER WAVE COMES ASHORE ACROSS CALIFORNIA TUESDAY NIGHT INTO WEDNESDAY...ALONG WITH APPROACHING WAVE DIVING SOUTH FROM THE NORTHWEST TERRITORIES. THIS WILL ENHANCE THE WARM ADVECTION/LOW LEVEL JET ACROSS THE CENTER OF THE NATION AND EXTEND INTO THE GREAT LAKES REGION THROUGH THE MIDDLE OF THIS WEEK. THIS WILL GRADUALLY CHANGE ANY PRECIP OVER TO ALL RAIN AND CONTINUE THROUGH THURSDAY. WITH 850MB JET IN EXCESS OF 50KTS AND PWATS CLIMBING OVER 1, WE COULD SEE SOME HEAVY RAINFALL WITH ANY CONVECTION. SWI/S AT OR BELOW 0C AND PARCELS LIFTED FROM 900MB SHOW CAPES AROUND 100 J/KG AND FREEZING LEVELS BELOW 10K FEET...WE MIGHT HAVE A SITUATION WITH A SQUALL LINE MOVING ACROSS THE STATE. WE ARE STILL ON TAP FOR A STRONG ARCTIC OUTBREAK THIS WEEKEND WITH STILL THE GFS ADVERTISING 850MB TEMPS OF -40C APPROACHING INTERNATIONAL FALLS BY SATURDAY (THE ECMWF IS SLIGHTLY WARMER) && .DTX WATCHES/WARNINGS/ADVISORIES... .MI...NONE. .LAKE HURON... GALE WARNING...NORTH HALF...THIS MORNING. SMALL CRAFT ADVISORY...SAGINAW BAY AND LAKE HURON NEARSHORE...THIS MORNING. .LAKE ST CLAIR...NONE. .MI WATERS OF LAKE ERIE...NONE. && $$ DWD/BGM HTTP://WWW.CRH.NOAA.GOV/DTX (ALL LOWER CASE)