FXUS63 KDTX 262031
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
331 PM EST SAT DEC 26 2009
.SHORT TERM...TONIGHT
500MB LOW OVER WISCONSIN WILL REMAIN NEARLY STATIONARY WHILE ITS
ASSOCIATED SURFACE LOW TRACKS NORTHEAST ACROSS NORTHERN LOWER. THIS
LOW WILL DRAG A COLD FRONT THROUGH THE AREA AFTER MIDNIGHT. AT THE
SAME TIME A VORT LOBE WILL ROTATE AROUND THE UPPER LOW AND THROUGH
SOUTHEAST MICHIGAN. THESE FEATURES WILL PROVIDE SUBTLE LIFT WITH
MOISTURE RELATIVELY DEEP UP TO 500MB AND SPECIFIC HUMIDITIES AROUND
2 G/KG GENERATING A COUPLE HUNDREDTHS OF QPF. SNOW SHOWERS ARE
LIKELY AND WITH SNOW RATIONS AROUND 20 TO 1, SOME AREAS IN THE
STRONGER SNOW BANDS MAY SEE AROUND AN INCH OF SNOW. LOWS WILL
GENERALLY DROP TO THE LOW TO MID 20S EXCEPT FOR UPPER 20S FAR
SOUTHEAST AND ALONG THE LAKESHORES.
&&
.LONG TERM...SUNDAY THROUGH NEXT SATURDAY
SEASONABLY COLD WEATHER WITH A FEW SNOW SHOWERS CAN BE EXPECTED
DURING MUCH OF THE UPCOMING WEEK.
THE SURFACE AND MID LEVEL LOW PRESSURE SYSTEMS OUT TO THE WEST WILL
PASS THROUGH THE CENTRAL GREAT LAKES ON SUNDAY PROVIDING A CONTINUED
CHANCE FOR SNOW SHOWERS TO THE AREA. WHILE THE SURFACE LOW WILL
TRACK NORTHEAST TOWARDS HUDSON BAY...THE 500 MB LOW WILL PASS
THROUGH SOUTHERN MICHIGAN. THIS ADDED LIFT WILL BRING A DECENT
CHANCE FOR MEASUREABLE SNOW WITH THE DYNAMICS MOVING INTO THE
CENTRAL GREAT LAKES. THE LIMITING FACTOR WILL CONTINUE TO BE
MOISTURE AS 285K MIXING RATIOS ARE ONLY AROUND 1 G/KG. WITH THE
EXPECTED FORCING AND INSTABILITY WILL RAISE PRECIP CHANCES TO LIKELY
WITH SNOWFALL AMOUNTS AROUND ON INCH DURING THE DAY ON SUNDAY.
THE MID LEVEL SUPPORT WILL BE OFF TO THE EAST SUNDAY NIGHT WITH
CONTINUED CHANCY POPS DURING THIS PERIOD. HOWEVER MONDAY WILL GET A
BOOST FROM DAYTIME HEATING PROVIDING INSTABILITY AS WELL AS A
SURFACE TROUGH SINKING SOUTH WITH AN EMBEDDED 500 MB SHORTWAVE. WITH
THE ADDED SUPPORT WILL KEEP HIGHER POPS IN ON MONDAY WITH THE
LIMITING FACTOR AGAIN BEING MOISTURE AND IF THE SCATTERED SNOW
SHOWERS WILL PROVIDE MEASUREABLE SNOWFALL AMOUNTS. THE BEST CHANCE
FOR THIS WILL BE ACROSS THE NORTHERN THUMB AS THE TROUGH TURNS WINDS
NORTHWESTERLY WITH ADDED MOISTURE FROM LAKE HURON. MONDAY WILL ALSO
PROVE TO BE QUITE WINDY AS HIGH PRESSURE SINKS SOUTH ACROSS THE
NORTHERN PLAINS AND INCREASES THE PRESSURE GRADIENT WITH 925 MB
WINDS INCREASING TO 35 KNOTS.
THIS HIGH PRESSURE SYSTEM WILL CONTINUE EAST ACROSS THE WESTERN
GREAT LAKES MONDAY NIGHT AND INTO THE CENTRAL GREAT LAKES ON TUESDAY
WITH THE AREA UNDER THE NORTH BRANCH OF A SPLIT FLOW REGIME DURING
THE MIDDLE PART OF THE WEEK. DESPITE THE HIGH BUILDING IN AND ENDING
THE SNOW ACROSS MUCH OF THE CWA...THE EASTERN THUMB MAY SEE LIGHT
SNOW OR FLURRIES MONDAY NIGHT AND EARLY TUESDAY WITH NORTHWEST FLOW
AND LAKE EFFECT SNOW SHOWERS UNTIL WINDS BECOME WESTERLY TUESDAY.
WITH A MARGINALLY FAVORABLE DIRECTION THE SNOW ACCUMULATIONS SHOULD
BE NEGLIGABLE DURING THIS PERIOD.
A WEAK CLIPPER SYSTEM WITH LIMITED MOISTURE WILL AFFECT THE WEATHER
TOWARDS THE END OF THE WEEK AS THE FLOW MERGES ACROSS THE EAST COAST
WITH A DEVELOPING NOREASTER. THE SLOWLY DEPARTING HIGH WILL KEEP THE
LOW AT BAY A BIT LONGER WITH THE BULK OF THE SNOW NOT EXPECTED TO
MAKE IT INTO THE CENTRAL GREAT LAKES UNTIL WEDNESDAY NIGHT AND
THURSDAY. THE GFS AND ECMWF HAVE DONE A ROLE REVERSAL FROM PREVIOUS
RUNS ON FRIDAY AND INTO THE WEEKEND AS THE GFS NOW KEEPS A CUT OFF
LOW ACROSS THE CENTRAL GREAT LAKES WHILE THE ECMWF IS MORE
PROGRESSIVE AND MERGES WITH THE LARGE EAST COAST STORM...ONLY
KEEPING A BROAD TROUGH WITH EMBEDDED SHORTWAVES ACROSS THE AREA.
DESPITE THE DIFFERENT MODEL SOLUTIONS IT LOOKS LIKE A SNOWY END TO
THE WORK WEEK AND START TO THE WEEKEND. WITH THE BEST MOISTURE WELL
TO THE EAST WITH THE STRONG DEVELOPING NOREASTER...VERY LIGHT
SNOWFALL ACCUMULATIONS ARE EXPECTED DURING THIS PERIOD WITH ONLY
CHANCY POPS ACROSS THE REGION.
&&
.MARINE...
GUSTY OFFSHORE WINDS WILL CONTINUE FOR THE REMAINDER OF THE WEEKEND
WITH NUMEROUS LIGHT SNOW SHOWERS AS LOW PRESSURE MOVES THROUGH THE
CENTRAL GREAT LAKES. THE OFFSHORE COMPONENT OF THE WINDS WILL KEEP
WAVES BELOW SMALL CRAFT CRITERIA AS WINDS STAY JUST BELOW SMALL
CRAFT CRITERIA GUSTING TO 20 TO 25 KNOTS.
THE PRESSURE GRADIENT WILL INCREASE SIGNIFICANTLY WITH THE DEPARTING
LOW TO THE EAST AND APPROACHING HIGH PRESSURE SYSTEM FROM THE WEST
MONDAY AND MONDAY NIGHT. NORTHWEST WINDS WILL GUST TO GALE FORCE
ACROSS LAKE HURON...WITH GUSTS TO 30 KNOTS ACROSS LAKE ST CLAIR AND
WESTERN LAKE ERIE DURING THIS PERIOD. GALE WATCHES ARE LIKELY IN THE
NEAR FUTURE ACROSS MUCH OF THE OPEN AND NEARSHORE WATERS OF LAKE
HURON.
&&
.PREV DISCUSSION...ISSUED 1110 AM EST SAT DEC 26 2009
AVIATION...
UPPER LEVEL CLOSED LOW OVER WISCONSIN WILL SLOWLY MOVE EAST TO OVER
SOUTHEAST LOWER MICHIGAN BY 00Z MON. ASSOCIATED SURFACE LOW WILL
TRACK NORTHEAST. MOST LIGHT SNOW SHOWER ACTIVITY WILL STAY TO THE
WEST OF THE TAF SITES THIS AFTERNOON CLOSER TO THE UPPER SUPPORT. A
BAND OF SNOW SHOWERS WITH MVFR CIGS AND VISIBILITIES ASSOCIATED WITH
A SURFACE TROUGH WILL ROLL THROUGH BETWEEN 03Z AND 09Z. ANOTHER
BAND OF SNOW SHOWERS WILL AFFECT DTW AFTER 21Z SUNDAY ASSOCIATED
WITH THE UPPER LOW. THERE IS A CHANCE OF FLURRIES AT ANY TIME AT
ALL TAF SITES BUT JUST MENTION THE BEST CHANCE FOR ANY SIGNIFICANT
SNOW IN TAFS.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
SHORT TERM...DRC
LONG TERM....KURIMSKI
MARINE.......KURIMSKI
AVIATION.....DRC
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
