AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
215 PM PST THU DEC 20 2007
.SYNOPSIS...A LOW PRESSURE TROUGH MOVING ACROSS THE WILL BRING
CLOUDS AND SCATTERED SHOWERS THROUGH EARLY FRIDAY MORNING...MAINLY
WEST OF THE MOUNTAINS...AND GUSTY WEST TO NORTHWEST WINDS TO THE
MOUNTAINS AND DESERTS. THE WINDS SHIFT NORTHEAST TONIGHT...WITH
GUSTY OFFSHORE WINDS IN THE MOUNTAIN PASSES THROUGH FRIDAY
AFTERNOON. DRY WEATHER WITH PERIODS OF GUSTY OFFSHORE WINDS WILL
PREVAIL THROUGH THE MIDDLE OF NEXT WEEK. WINTER BEGINS AT 1008 PM
FRIDAY.
&&
.DISCUSSION...FOR SOUTHWEST CALIFORNIA INCLUDING SAN DIEGO...
ORANGE...SOUTHWEST SAN BERNARDINO AND WEST RIVERSIDE COUNTIES.
.SHORT TERM...TONIGHT THROUGH SUNDAY...
FRONT PUSHING ACROSS VENTURA COUNTY AT THIS TIME...MOVING EAST TO
SOUTHEAST NEAR 30 MPH. LIGHT TO BRIEFLY MODERATE RAIN EXPECTED TO
BEGIN ORANGE COUNTY/SW SAN BERNARDINO COUNTY AROUND 400 PM AND
NORTHERN SAN DIEGO/WESTERN RIVERSIDE COUNTIES AROUND 600 PM. COLD
CORE OF AIR MOVING ACROSS THE FORECAST AREA BETWEEN 700 PM AND 200
AM. THIS SHOULD LOWER SNOW LEVEL TO AROUND 4000 FEET AND ALSO
DESTABILIZE AIR MASS FOR SLIGHT CHANCE OF THUNDERSTORMS WITH SMALL
HAIL. HOWEVER AIR MASS RAPIDLY STABILIZES AFTER MIDNIGHT SO BY 400
AM HAVE PRECIPITATION THREAT ENDING. USED A 15 TO 1 SNOW TO WATER
RATIO FOR MOUNTAINS...THIS YIELDS 1 TO 4 INCHES OF SNOW. OTHERWISE
DID NOT CHANGE QPF GRIDS. DO NOT ANTICIPATE SIGNIFICANT QPF CHANGES
BEING MADE IN THE 1600 PST ISSUANCE. RIDGING ON FRIDAY WITH COLD
NORTH TO NORTHEAST FLOW. WIND DIRECTION SHIFTING TO NORTHEAST TO
EAST FRIDAY NIGHT INTO SATURDAY MORNING AS SURFACE HIGH PRESSURE
CENTERED OVER GREAT BASIN SHIFTS EASTWARD IN RESPONSE TO TROUGH
APPROACHING PACIFIC NORTHWEST STATES. THIS TROUGH MOVES QUICKLY
INLAND AND HIGH PRESSURE REBUILDS OVER THE GREAT BASIN ON SUNDAY.
END RESULT IS TEMPORARY LESSENING OF OFFSHORE FLOW SATURDAY
AFTERNOON/NIGHT WITH INCREASING OFFSHORE WINDS SUNDAY AFTERNOON.
.LONG TERM...
A SERIES OF SHORTWAVES WILL TRACK ACROSS THE GREAT BASIN NEXT WEEK
BRING PERIODS OF BLUSTERY OFFSHORE WINDS. THE GFS PROJECTS A
MODERATELY STRONG...COLD OFFSHORE WIND EVENT TUESDAY
MORNING...FOLLOWED BY A SLIGHTLY WEAKER WIND EVENT THURSDAY MORNING.
&&
.AVIATION...
202000Z...MDCRS SOUNDINGS CONTINUE TO SHOW THE MARINE LAYER DEPTH
AROUND 4000 FEET THIS AFTERNOON. EXPECT LITTLE CHANGE IN THE DEPTH
THROUGH THIS EVENING THEN LOWERING LATE TONIGHT BEHIND A WEAK COLD
FRONT THAT IS EXPECTED TO PASS THROUGH THE AREA BETWEEN 04Z AND 07Z.
BROKEN TO OVERCAST LAYERS OF STRATOCU WITH BASES BETWEEN 2500 AND
3500 FEET MSL SHOULD CONTINUE THROUGH THIS EVENING. VISIBILITIES
SHOULD REMAIN UNRESTRICTED EXCEPT FOR AREAS OF MVFR TO LOCAL IFR
VISIBILITIES IN SHOWERS THIS AFTERNOON AND EVENING. SHOWERS MAY ALSO
LOWER CLOUD BASES TO 1000 FEET OR LESS AT TIMES ESPECIALLY DURING
FRONTAL PASSAGE. STRATOCU SHOULD BREAK UP BETWEEN MIDNIGHT AND
SUNRISE AND SHOWERS SHOULD END DURING THIS PERIOD WITH MOSTLY CLEAR
TO SCATTERED CONDITIONS ON FRIDAY. HORTON
&&
.MARINE...HIGHER THAN NORMAL WEST NORTHWEST SWELL WILL MOVE INTO THE
COASTAL WATERS TONIGHT INTO FRIDAY MORNING. THIS IS EXPECTED TO
BRING HIGHER THAN NORMAL SURF TO THE BEACHES OF SAN DIEGO COUNTY
WITH SOME INCREASE IN SURF ALONG THE ORANGE COUNTY BEACHES AS WELL.
THE SWELL WILL SUBSIDE DURING THE EVENING ON FRIDAY. ALSO...MORNING
ASTRONOMICAL HIGH TIDES OF 7 FEET OR HIGHER ARE FORECAST BEGINNING
FRIDAY MORNING AND CONTINUING THROUGH CHRISTMAS DAY. THIS COULD
BRING SOME MINOR TIDAL OVERFLOW TO LOW LYING BEACH AREAS DURING THE
MORNING HIGH TIDES. HORTON
&&
.FIRE WEATHER...A MORE OR LESS CONTINUOUS PERIOD OF OFFSHORE FLOW
AND DRYING FRIDAY THROUGH NEXT WEDNESDAY ADVERTISED BY THE MODELS.
RECENT PRECIPITATION SHOULD OFFSET THIS DRYING TREND...AT LEAST
THROUGH THE WEEKEND BUT BY NEXT WEEK NOT SO CERTAIN. LATE CHRISTMAS
EVE THROUGH CHRISTMAS DAY MODELS CONTINUE TO INDICATE HIGH AMPLITUDE
RIDGE BUILDING ALONG WEST COAST AND A +1035 MB HIGH OVER THE GREAT
BASIN. LOCAL PROGRAMS USING GFS MODEL AS INPUT CONTINUE TO SHOW A 12
HOUR PERIOD OF SUSTAINED WINDS/GUSTS AND RELATIVE HUMIDITY MEETING
THRESHOLDS FOR CRITICAL FIRE WEATHER CONDITIONS ON CHRISTMAS DAY.
WILL FURTHER COORDINATE WITH FWC RIVERSIDE FRIDAY MORNING.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...WIND ADVISORY UNTIL 10 AM PST FRIDAY FOR COACHELLA VALLEY-SAN
DIEGO COUNTY DESERTS.
WIND ADVISORY UNTIL 2 PM PST FRIDAY FOR RIVERSIDE COUNTY
MOUNTAINS-SAN BERNARDINO COUNTY MOUNTAINS-SAN DIEGO COUNTY
MOUNTAINS.
COASTAL FLOOD ADVISORY FROM 8 PM THIS EVENING TO 2 PM PST
TUESDAY FOR ORANGE COUNTY COASTAL AREAS-SAN DIEGO COUNTY
COASTAL AREAS.
WIND ADVISORY FROM 10 PM THIS EVENING TO 2 PM PST FRIDAY FOR
SAN BERNARDINO AND RIVERSIDE COUNTY VALLEYS-THE INLAND
EMPIRE- SANTA ANA MOUNTAINS AND FOOTHILLS.
WIND ADVISORY UNTIL 10 PM PST THIS EVENING FOR APPLE AND
LUCERNE VALLEYS.
PZ...SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 7 AM PST FRIDAY
FOR WATERS FROM SAN MATEO POINT TO THE MEXICAN BORDER
EXTENDING 30 TO 60 NM OUT INCLUDING SAN CLEMENTE ISLAND.
&&
$$
PUBLIC...BALFOUR
AVIATION/MARINE...HORTON
NWS ON THE WEB AT WEATHER.GOV/SANDIEGO
AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
945 AM PST THU DEC 20 2007
.SYNOPSIS...A LOW PRESSURE TROUGH WILL BRING CLOUDS AND INCREASING
CHANCES FOR SHOWERS LATER TODAY AND TONIGHT...MAINLY FROM THE
MOUNTAINS WESTWARD. THIS TROUGH WILL BRING GUSTY WEST WINDS TO THE
HIGH DESERTS AND MOUNTAINS THIS AFTERNOON AND EVENING. THE WINDS
SHIFT NORTHEAST TONIGHT...WITH GUSTY OFFSHORE WINDS IN THE MOUNTAIN
PASSES THROUGH FRIDAY AFTERNOON. DRY WEATHER WITH PERIODS OF GUSTY
OFFSHORE WINDS WILL PREVAIL THROUGH THE MIDDLE OF NEXT WEEK. WINTER
BEGINS AT 1008 PM FRIDAY.
&&
.DISCUSSION...FOR SOUTHWEST CALIFORNIA INCLUDING SAN DIEGO...
ORANGE...SOUTHWEST SAN BERNARDINO AND WEST RIVERSIDE COUNTIES.
.SHORT TERM...ONLY CHANGE TO CURRENT FORECAST IS TO INCLUDE LOWER
DESERTS IN A WIND ADVISORY BEGINNING THIS AFTERNOON AND AS MENTIONED
IN THE MARINE DISCUSSION BELOW...ADD MINOR TIDAL OVERFLOW TO THE
COASTS. OTHERWISE THE FORECAST LOOKS ON TRACK. THE MARINE LAYER WAS
DEEP ENOUGH COUPLED WITH UPSLOPE FLOW TO GENERATE AREAS OF DRIZZLE
THIS MORNING. ADDITIONAL LIFTING AND MOISTURE ADVECTION THROUGHOUT
THE DAY AND TROUGH ADVANCING TOWARDS THE AREA WILL GENERATE MORE
WIDESPREAD LIGHT RAIN/SNOW LATE THIS AFTERNOON THROUGH TONIGHT FOR
MOST OF SOUTHWEST CALIFORNIA. MIGHT ADD A SLIGHT CHANCE OF
THUNDERSTORMS TONIGHT/EARLY FRIDAY MORNING FOR WHEN THE COLD CORE
COMES ACROSS. AS FOR STORM TOTAL PRECIPITATION CURRENT QPF FORECAST
LOOKS GOOD AND DO NOT ANTICIPATE SIGNIFICANT CHANGES BEING MADE IN
THE 1600 PST ISSUANCE. RIDGING ON FRIDAY WITH COLD NORTH TO
NORTHEAST FLOW. WIND DIRECTION SHIFTING TO NORTHEAST TO EAST FRIDAY
NIGHT INTO SATURDAY MORNING AS SURFACE HIGH PRESSURE CENTERED OVER
GREAT BASIN SHIFTS EASTWARD IN RESPONSE TO TROUGH APPROACHING
PACIFIC NORTHWEST STATES. THIS TROUGH MOVES QUICKLY INLAND AND HIGH
PRESSURE REBUILDS OVER THE GREAT BASIN ON SUNDAY. END RESULT IS
TEMPORARY LESSENING OF OFFSHORE FLOW SATURDAY AFTERNOON/NIGHT WITH
INCREASING OFFSHORE WINDS SUNDAY AFTERNOON.
LONG TERM...FROM PREVIOUS DISCUSSION...
A SERIES OF SHORTWAVES WILL TRACK ACROSS THE GREAT BASIN NEXT WEEK
BRING PERIODS OF BLUSTERY OFFSHORE WINDS. THE GFS PROJECTS A
MODERATELY STRONG...COLD OFFSHORE WIND EVENT TUESDAY
MORNING...FOLLOWED BY A SLIGHTLY WEAKER WIND EVENT THURSDAY MORNING.
&&
.AVIATION...
201545Z...BASED ON MDCRS SOUNDINGS AND MORNING TOP REPORTS...MARINE
LAYER DEPTH WAS AROUND 4000 FEET THIS MORNING. EXPECT LITTLE CHANGE
IN THE DEPTH THROUGH THIS EVENING THEN LOWERING LATE TONIGHT BEHIND
A WEAK COLD FRONT THAT IS EXPECTED TO PASS THROUGH THE AREA BETWEEN
04Z AND 07Z. BROKEN TO OVERCAST STRATOCU WITH BASES BETWEEN 2500 AND
3000 FEET MSL SHOULD CONTINUE THROUGH THIS EVENING. VISIBILITIES
SHOULD REMAIN UNRESTRICTED EXCEPT FOR AREAS OF MVFR TO LOCAL IFR
VISIBILITIES IN SHOWERS THIS AFTERNOON AND EVENING. SHOWERS MAY ALSO
LOWERING CLOUD BASES TO 1000 FEET OR LESS AT TIMES ESPECIALLY DURING
FRONTAL PASSAGE. STRATOCU SHOULD BREAK UP BETWEEN MIDNIGHT AND
SUNRISE AND SHOWERS SHOULD END DURING THIS PERIOD WITH MOSTLY CLEAR
TO SCATTERED CONDITIONS ON FRIDAY. HORTON
&&
.MARINE...HIGHER THAN NORMAL WEST NORTHWEST SWELL WILL MOVE INTO THE
COASTAL WATERS TONIGHT INTO FRIDAY MORNING. THIS IS EXPECTED TO
BRING HIGHER THAN NORMAL SURF TO THE BEACHES OF SAN DIEGO COUNTY
WITH SOME INCREASE IN SURF ALONG THE ORANGE COUNTY BEACHES AS WELL.
THE SWELL WILL SUBSIDE DURING THE EVENING ON FRIDAY. ALSO...MORNING
ASTRONOMICAL HIGH TIDES OF 7 FEET OR HIGHER ARE FORECAST BEGINNING
FRIDAY MORNING AND CONTINUING THROUGH CHRISTMAS DAY. THIS COULD
BRING SOME MINOR TIDAL OVERFLOW TO LOW LYING BEACH AREAS DURING THE
MORNING HIGH TIDES. HORTON
&&
.FIRE WEATHER...PROLONGED PERIOD OF OFFSHORE FLOW FRIDAY THROUGH
NEXT WEDNESDAY. RECENT PRECIPITATION SHOULD OFFSET THE STRONG DRYING
AND WARMING TREND...AT LEAST THROUGH THE WEEKEND. GROWING CONCERN
ABOUT CHRISTMAS DAY WHEN THE OFFSHORE WINDS ARE FORECAST TO
STRENGTHEN AGAIN. MODELS ARE IN PHASE NOW AND BOTH THE ECMWF AND GFS
MODELS HAVE SUSTAINED WINDS/GUSTS AND RELATIVE HUMIDITY MEETING
THRESHOLDS FOR CRITICAL FIRE WEATHER CONDITIONS.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...WIND ADVISORY UNTIL 2 PM PST FRIDAY FOR RIVERSIDE COUNTY
MOUNTAINS-SAN BERNARDINO COUNTY MOUNTAINS-SAN DIEGO COUNTY
MOUNTAINS.
WIND ADVISORY UNTIL 10 PM PST THIS EVENING FOR APPLE AND LUCERNE
VALLEYS.
WIND ADVISORY FROM 2 PM THIS AFTERNOON TO 10 AM PST FRIDAY
FOR COACHELLA VALLEY-SAN DIEGO COUNTY DESERTS.
WIND ADVISORY FROM 10 PM THIS EVENING TO 2 PM PST FRIDAY FOR SAN
BERNARDINO AND RIVERSIDE COUNTY VALLEYS-THE INLAND EMPIRE-
SANTA ANA MOUNTAINS AND FOOTHILLS.
COASTAL FLOOD ADVISORY FROM 8 PM THIS EVENING TO 2 PM PST
TUESDAY FOR ORANGE COUNTY COASTAL AREAS-SAN DIEGO COUNTY
COASTAL AREAS.
PZ...SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 7 AM PST FRIDAY
FOR WATERS FROM SAN MATEO POINT TO THE MEXICAN BORDER
EXTENDING 30 TO 60 NM OUT INCLUDING SAN CLEMENTE ISLAND.
&&
$$
PUBLIC/FIRE WEATHER...BALFOUR
AVIATION/MARINE...HORTON
NWS ON THE WEB AT WEATHER.GOV/SANDIEGO
AREA FORECAST DISCUSSION
NWS CHICAGO IL
843 AM CST WED DEC 19 2007
.DISCUSSION...
843 AM CST
GOES 3.9 MICRON IMAGERY THIS MORNING IS DOING A NICE JOB DEPICTING
AN EXPANDING FOG BANK FROM FAR NORTHWEST IL SOUTHEASTWARD INTO THE
KPNT AREA. KDVN SOUNDING SHOWED A VERY SHARP NOCTURNAL INVERSION IN
PLACE WITH RECENT ACARS FLIGHT OUT OF RFD SHOWING A SIMILAR
PROFILE...WHICH WILL LIKELY RESULT IN ONLY A VERY SLOW LIFTING OF
THE FOG THIS MORNING. LIGHT NORTHWESTERLY LOW LEVEL FLOW IS
ALLOWING THE FOG TO SLOWLY SPREAD EASTWARD AND VSBYS AT VARIOUS
AWOS/ASOS SITES HAVE RESPONDED TANKING TO <1/2SM.
GIVEN THESE TRENDS HAVE GONE AHEAD AND ISSUED A FREEZING FOG
ADVISORY THROUGH LATE MORNING.
IZZI
&&
.PREV DISCUSSION...
250 AM...WEAK COLD FRONT JUST ABOUT EAST OF THE AREA EARLY THIS
MORNING WITH SOME STRATOCU MOVING ACROSS NORTHERN IL. MAIN CONCERN
TODAY IS HOW LONG LOW CLOUDS STICK AROUND AND HIGH TEMPS. SOUNDINGS
AND TIME HEIGHT SECTIONS SUGGEST LOW CLOUDS WILL BE ON THE DECREASE
BY LATE MORNING AND PROBABLY ONLY ACROSS THE NORTH THIRD/HALF OF
THE CWA. SOME LARGE BREAKS CURRENTLY FORMING ACROSS WI SO TODAY MAY
END UP BEING MORE PARTLY CLOUDY NORTH. AS FOR HIGHS...SOME CHILLY
AIR NOT TOO FAR AWAY WITH MID TEENS ACROSS CENTRAL IA...UNDER CLEAR
SKIES AND TEMPS ALREADY DROPPING INTO THE LOWER 20S ACROSS WESTERN
IL. TEMPS LIKELY TO STRUGGLE BACK INTO THE LOW 30S WEST...MID 30S
EAST SO PLAN TO STAY ON THE LOW SIDE OF GUIDANCE TODAY.
SYSTEM FOR THURSDAY AFTERNOON/THURSDAY NIGHT MUCH WEAKER AND APPEARS
TO MAINLY LIGHT WAA PRECIP AS ONE WEAK SHORTWAVE HEADS NORTH OF THE
AREA AND THE STRONGER WAVE WELL SOUTH OF THE AREA. GOING FORECAST
HAS A SLIGHT CHANCE OF RAIN BY AFTERNOON AND HAVE KEPT THIS ONLY IN
THE WESTERN CWA AS MOST OF THE DAYLIGHT HRS APPEAR DRY. BEST CHANCE
IS THURSDAY NIGHT...AND STILL LOW. UNDER CLOUDY SKIES LOWS ONLY DIP
INTO THE UPPER 20S AND LOWER 30S AND A CHANCE OF FREEZING DRIZZLE
ALSO SEEMS POSSIBLE. WILL ALSO ADD SOME PATCHY FOG THURSDAY NIGHT
AND FRIDAY AS WARM AIR LIFTS OVER COLDER SNOWPACK. HIGHS WARM A FEW
DEGREES MORE FRIDAY BUT WITH CLOUDS/DRIZZLE/FOG...WILL ONCE AGAIN
STAY BELOW GUIDANCE FOR HIGHS.
THEN COMES THIS WEEKEND. MODELS APPEAR TO BE GOING THROUGH SOME
CHANGES IN EVOLUTION AND TRACK OF SFC LOW WHICH DEVELOPS OVER THE
SOUTHERN PLAINS FRIDAY NIGHT AND LIFTS NORTHEAST TOWARD THE LAKES
SATURDAY AND SATURDAY NIGHT. THE 06Z GFS TUESDAY MORNING CONTINUED
TO SHOW A SHIFT TO THE EAST WITH THE TRACK OF THE LOW. THE 00Z GFS
RUN THIS MORNING CONTINUES TO SHOW A SFC LOW TRACKING TO THE
SOUTHEAST OF THE CWA...BUT WEAKER. AT 00Z SUNDAY...THE ECMWF HAS
THE SFC LOW IN ALMOST THE SAME SPOT AS THE GFS...OVER SOUTHEAST MO.
THE CANADIAN ALSO HAS SHIFTED THE TRACK OF THE LOW SLIGHTLY FURTHER
EAST...BUT STILL OVER THE WESTERN LAKES WITH THE UKMET THE FARTHEST
WEST. WHILE A FARTHER SOUTHEAST TRACK OF THE LOW IS BY NO MEANS
CERTAIN 4 DAYS OUT...IT DOES APPEAR THE GFS HAS PICKED UP ON A
FURTHER SOUTHEAST TRACK WHICH THE OTHER MODELS ARE NOW TRENDING
TOWARD. ALSO OF NOTE IS THE GFS ENSEMBLES WHICH SHOW A LARGE
VARIATION IN TIMING BUT ARE ALL SOUTHEAST OF THE CWA WITH THE TRACK
OF THE SFC LOW. SYSTEMS LIKE THESE OFTEN TEND TO TAKE LONGER TO
EVOLVE...THUS WOULD EXPECT MODELS TO SLOW THIS SYSTEM DOWN WITH
FUTURE RUNS. USUALLY PREFER NOT TO MAKE SIGNIFICANT CHANGES THIS
FAR OUT BUT WILL INDICATE MORE OF A RAIN/SNOW MIX BY AFTERNOON
ACROSS THE WESTERN CWA AND ALL SNOW ACROSS THE WESTERN CWA SATURDAY
NIGHT AS CONFIDENCE IS INCREASING OF MORE OF A SNOW EVENT ACROSS NW
IL BUT STILL TOO EARLY TO SAY FOR SURE. WILL ALSO LOWER HIGH TEMPS
SUNDAY WITH A GOOD SHOT OF COLD AIR. CMS
&&
.AVIATION...
530 AM CST
FOR THE 12Z TAFS...HAVE BEEN TRACKING TRAJECTORY OF SC WRAPAROUND IN
WI FOR LAST 6 HRS. OBSERVING LARGE OPENING EXPANDING EVEN FURTHER
WITH RING OF SC DIVING SE THRU TERMINALS. THIS SHUD BE THRU
TERMINALS EXCEPT FOR GYY AT 12Z. LARGE HOLE IN WI GETTING BIGGER
WITH MOVEMENT OF CLOUD PATTERN IN WRN WI TAKING MORE OF A SWD TRACK
AROUND TERMINALS. WUD LIKE TO JUST GO SCT AROUND 15 HUNDRED FOR THIS
MORNING AND CLEAR REST OF DAY. WILL COVER SCT WITH A COUPLE HOURS OF
TEMPO BKN IN PRE-NOON HOURS...THEN FORGET ABOUT IT AS WE MOVE INTO A
WEAK ANTICYCLONIC FLOW AS WEAK RIDGING CROSSES THE MS RVR VLY. WINDS
SHUD BACK FROM WNW TO W AND GO L/V THIS EVENING UNDER SAID RIDGING.
WILL LEAVE IT THAT WAY OVERNIGHT WED NGT WITH WAA CI SPREADING OVER
THE MIDWEST OVERNIGHT AHEAD OF NEXT RAIN PRODUCER MOVING THIS WAY.
DEPENDING ON SFC TEMPS...THIS CUD BE A FREEZING RAIN PRODUCER BY
THURSDAY NIGHT.
RLB
&&
.MARINE...
250 AM CST
WINDS HAVE SHIFTED TO THE NW BEHIND A PASSING COLD FRONT WHICH SHUD
CONTINUE AN EASTWARD SWEEP TOWARD NEW ENGLAND. WEAK HIGH PRESSURE
WILL BUILD OVER THE LAKES TODAY...WEAKENING WINDS TONIGHT. WINDS
WILL BE STRENGTHENING AGAIN THURSDAY FROM THE EAST AND SOUTHEAST.
THIS FEED FROM THE SE IS IN ADVANCE OF A DEEPENING STORM SYSTEM
MOVING UP FROM THE PLAINS THRU THE LOWER OH VLY BY THE WEEKEND.
WINDS WILL INTENSIFY TO 25 KTS FRIDAY AND TO 30 KNOTS BY SUNDAY
VEERING TO THE NORTHWEST SAT NGT WITH ANOTHER PASSING FRONTAL
SYSTEM. WINDS CUD APPROACH GALE FORCE SUNDAY BUT WILL HOLD BACK ON
THE HEADLINES FOR NOW.
RLB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...FREEZING FOG ADVISORY UNTIL 11 AM CST THIS MORNING FOR ILZ003-
008-010-011-019-032.
IN...NONE.
LM...NONE.
&&
$$
WFO LOT
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1240 PM EST THU DEC 20 2007
.LATE MORNING UPDATE....
THE CONCERN FOR THIS FORECAST PERIOD WILL CONTINUE TO BE THE TIMING
OF PRECIPITATION INTO THE FORECAST AREA. THE RAIN IS A LITTLE
FURTHER NORTHEAST THAN MODELS WOULD SUGGEST BUT IT HAS BEEN SLOWING.
THE LATEST (15Z) ACARS SOUNDING FROM SDF INDICATES A VERY DRY LOWER
ATMOSPHERE WITH A CONTINUED SOUTHEAST FLOW THROUGH 800MB. THIS WILL
SERVE TO KEEP THE ATMOSPHERE DRY FOR A WHILE LONGER SO WE WILL HOLD
WITH THE CURRENT MODEL TRENDS OF BRINGING PRECIPITATION IN LATE IN
THE DAY WITH THE BEST CHANCE FOR PRECIPITATION TONIGHT. SO WE WILL
MAKE ONLY MINOR CHANGES TO THE CURRENT FORECAST.
PREVIOUS DISCUSSION BELOW...
SHORT TERM (TODAY AND TONIGHT)...
AN UPPER LEVEL DISTURBANCE WILL STRENGTHEN SLIGHTLY AS IT MOVES FROM
THE SOUTHERN PLAINS INTO THE SOUTHEAST UNITED STATES. IN CONJUNCTION
A SURFACE LOW WILL SLIDE FROM OKLAHOMA TO ALABAMA WITH A WARM FRONT
REACHING NORTHEAST INTO KENTUCKY. AN AREA OF MOISTURE REVEALED BY
THUNDERSTORMS OVER SOUTHEAST TEXAS THIS MORNING WILL SWELL
NORTHEASTWARD...REACHING KENTUCKY THIS AFTERNOON AND SPREADING
THROUGHOUT CENTRAL KENTUCKY AND SOUTHERN INDIANA THIS EVENING
BRINGING PATCHY LIGHT RAIN WITH IT. WILL INCREASE POPS QUITE A BIT
OVER THE NORTH TO ACCOUNT FOR AREAL COVERAGE OF LIGHT RAIN BUT
ACTUAL AMOUNT OF RAIN IN THE NORTH WILL BE SMALL...PERHAPS ONE OR
TWO TENTHS OF AN INCH. POPS IN THE SOUTH WILL ONLY BE RAISED A
LITTLE BIT...BUT WITH HIGHER QPF NUMBERS AROUND HALF AN INCH NEAR
THE TENNESSEE BORDER.
.LONG TERM (FRIDAY THROUGH WEDNESDAY)...
UPPER FLOW THROUGHOUT THE EXTENDED PERIOD WILL GENERALLY BE
CHARACTERIZED BY A FAST WESTERLY FLOW ACROSS THE CONUS...WITH A
SERIES OF TROUGHS MOVING EASTWARD FROM THE CENTRAL ROCKIES THROUGH
THE MIDWEST.
FRIDAY THROUGH SUNDAY...
RAIN THURSDAY NIGHT WILL END EARLY FRIDAY AS A WEAK TROUGH
ASSOCIATED WITH THE SOUTHERN JET MOVES EASTWARD ACROSS THE GULF
STATES. EVEN THOUGH THE MID LEVELS WILL DRY OUT WITH THE LOSS OF
FORCING...AMPLE RH WILL REMAIN BELOW 6K FEET...AND WILL WORD FRIDAY
AFTERNOON AS MOSTLY CLOUDY.
TEMPERATURES WILL REMAIN QUITE MILD FRIDAY AND FRIDAY NIGHT...WITH
HIGHS FRIDAY AND EARLY MORNING LOWS SATURDAY REMAINING AROUND 10
DEGREES ABOVE SEASONAL NORMS.
A VIGOROUS STORM SYSTEM WILL ENTER THE WESTERN CONUS LATE THURSDAY
AND WILL LEAD TO AN AMPLIFICATION OF A TROUGH OVER THE ROCKIES
FRIDAY. THIS TROUGH WILL QUICKLY MOVE EAST AND MAY ASSUME A NEGATIVE
TILT AS IT MOVES ACROSS THE LOWER OHIO VALLEY LATE SATURDAY OR EARLY
SUNDAY. THE 00Z NAM AND GFS OPERATIONAL MODELS PRESENT A DIFFERENT
EVOLUTION OF THE TROUGH AND THE SURFACE LOW. THE NAM QUICKLY SWINGS
A NEGATIVELY TILTED TROUGH THROUGH KENTUCKY EARLY SUNDAY AS IT
RAPIDLY DEEPENS A SURFACE LOW ACROSS THE WESTERN GREAT LAKES BY
SUNDAY MORNING. THE NAM BRINGS A DEEP CLOSED 500MB CLOSED LOW QUITE
FAR SOUTH ACROSS IOWA BY EARLY SUNDAY. THE SLOWER GFS PRESENTS MORE
OF AN OPEN AMPLIFIED TROUGH...THAT DOESN`T MOVE ACROSS THE REGION
UNTIL LATER IN THE DAY SUNDAY. THE GFS DEEPENS THE SURFACE LOW MORE
SLOWLY AND FARTHER EAST LATE SUNDAY.
IN ANY EVENT...THIS SYSTEM WILL BRING RAIN SHOWERS AND PROBABLY SOME
GUSTY WINDS ACROSS THE AREA LATE SATURDAY OR EARLY SUNDAY. THE
STRONGER GFS DEVELOPS A 45KT 925MB LOW LEVEL JET LATE SATURDAY JUST
AHEAD OF THE SURFACE FRONT. WINDY CONDITIONS MAY DEVELOP IN
ASSOCIATION WITH THIS JET...AND ALSO RIGHT BEHIND THE COLD
FRONT...WHEN MUCH COLDER AIR WILL FLOOD THE AREA. THIS SYSTEM WILL
HAVE STRONG DYNAMICS AND FORCING. THE STRENGTH OF THE JET MAX
ROUNDING THE BASE OF THE TROUGH AND KENTUCKY`S RELATIVE POSITION
UNDER THE NOSE OF THIS JET MAY PROVIDE ENOUGH INSTABILITY FOR
SCATTERED THUNDERSTORMS.
WILL NOT ALTER TOO MUCH OUR CURRENT FORECAST AND WILL CONTINUE
LIKELY POPS SATURDAY NIGHT...DIMINISHING EARLY SUNDAY. VERY MILD
TEMPERATURES NEAR 60 ARE LIKELY SATURDAY...WITH POSSIBLY STEADY OR
FALLING TEMPS SUNDAY. MID LEVEL MOISTURE WILL BE SCOURED OUT SUNDAY
AS DRY SLOT OF THE CYCLONE TO OUR NORTH ROTATES OVERHEAD.
LATE SUNDAY THROUGH WEDNESDAY...
PARTLY CLOUDY SKIES WITH SEASONABLY COOL TEMPERATURES WILL CONTINUE
THROUGH LATE MONDAY AS HIGH PRESSURE SLIDES SOUTHEAST ACROSS THE
LOWER OHIO VALLEY.
THE FORECAST FOR CHRISTMAS DAY LOOKS A BIT TRICKY. THE OPERATIONAL
GFS AND ESPECIALLY THE OPERATIONAL ECMWF BRING A TROUGH ACROSS THE
LOWER MISSISSIPPI VALLEY LATE MONDAY AND OVER THE TENNESSEE VALLEY
TUESDAY. SHOULD THIS OCCUR LIGHT RAIN OR SNOW MAY DEVELOP DURING THE
DAY...WITH KENTUCKY LOCATED ON THE NORTHERN EDGE OF THE
PRECIPITATION SHIELD. HOWEVER...THE 12Z GFS ENSEMBLES SHOW ALMOST NO
HINT OF THIS TROUGH AND HAS NO PRECIPITATION TUESDAY. FOR NOW WILL
NOT ALTER ONGOING MENTION OF MIXED PRECIP ON CHRISTMAS DAY.
AT THIS POINT...WEDNESDAY LOOKS DRY WITH SEASONABLE TEMPERATURES.
&&
.AVIATION (18Z TAFS)...
AN UPPER LEVEL DISTURBANCE MOVING ACROSS THE WESTERN GULF COAST
STATES WILL PUMP MOISTURE INTO SOUTHERN AND CENTRAL KENTUCKY THIS
AFTERNOON AND TONIGHT. SHOWERS JUST SOUTHWEST OF BWG WILL GRADUALLY
SHIFT NORTHEAST THIS AFTERNOON AND TONIGHT. ENOUGH INSTABILITY
EXISTS OVER THE SOUTH TO MENTION A FEW HOURS WITH THUNDER AT BWG.
THE RAIN WILL MOVE ACROSS SDF AROUND 00Z AND LEX BY 03Z. I EXPECT
CIGS TO DROP INTO THE MVFR OR UPPER IFR RANGE WITH VSBYS AT BWG
EXPECTED TO DROP INTO THE IFR RANGE TONIGHT. THE RAIN WILL END BY
10Z FRIDAY BUT CIGS WILL REMAIN LOW.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
SHORT TERM...JA
LONG TERM....JSD
AVIATION.....JA
AREA FORECAST DISCUSSION
NWS GAYLORD MI
1002 PM EST THU DEC 20 2007
.UPDATE...BROAD WARM ADVECTION PATTERN IN PLACE ACROSS THE WESTERN
GREAT LAKES THIS EVENING...WITH VEERING WINDS FROM THE SURFACE
(SOUTHEAST) UP THROUGH 500MB (WEST-SOUTHWEST). RADAR RETURNS HAVE
BEEN DEVELOPING WITHIN THIS PATTERN ACROSS LAKE MICHIGAN/FAR WESTERN
LOWER MI...WEST AND SOUTHWEST INTO WI/NORTHERN IL WITHIN AN AXIS OF
STEEPER MID LEVEL LAPSE RATES. LOW LAYERS ARE DRIER FARTHER NORTH
AND EAST PER 00Z APX/DTX/GRB SOUNDINGS...WITH A DRY WEDGE OF AIR
BELOW 700MB...WHILE AIRCRAFT SOUNDINGS OUT OF WESTERN UPPER/
NORTHWEST WI INDICATING A MORE SATURATED COLUMN. LOW ST DECK
HANGING IN ACROSS FAR EASTERN UPPER AND CLIPPING NORTHEAST LOWER
AROUND PZQ-APN.
LOW LEVEL DRY AIR EXPECTED TO REMAIN GENERALLY INTACT OVERNIGHT
GIVEN UPSTREAM CONDITIONS AND PERSISTENT SOUTHEAST/SOUTH LOW LEVEL
FLOW. SO WILL KEEP THE FORECAST DRY...EXPECTING AS LOW LEVEL
MOISTURE EVIDENT ON MPX/DVN/ILX SOUNDINGS WORKS INTO THE AREA FRIDAY
DRIZZLE OR LIGHT RAIN WILL BE MORE OF AN ISSUE. THUS FAR
TEMPERATURE/DEW POINT SPREADS HAVE REMAINED FAIRLY CONSISTENT
(GENERALLY 4-8 DEGREES)...CLOUDS/WINDS EXPECTED TO REMAIN PERSISTENT
THROUGH THE NIGHT. HIGHER TERRAIN AREAS MOST PROBABLE AREAS TO SEE
SOME FOG DEVELOPMENT OVERNIGHT DUE TO UPSLOPE FLOW.
JPB
&&
.PREV DISCUSSION... /ISSUED 409 PM EST THU DEC 20 2007/
RATHER FLAT SHORTWAVE RIDGE ACROSS THE GREAT LAKES TONIGHT WITH
SURFACE HIGH PRESSURE SLIDING EAST OF AREA. A WEAK SHORTWAVE TROF
OVER WISCONSIN WILL MOVE TOWARD THE WESTERN LAKES TONIGHT...BUT
WITH NO UPPER SUPPORT AND LIMITED MOISTURE...WILL LIKELY ONLY
PRODUCE MID/HIGH CLOUDS. ONE EXCEPTION WILL BE OVER NORTHERN
CHIPPEWA COUNTY...WHERE A FEW FLURRIES WILL BE POSSIBLE CLOSER TO
THE VORTICITY CENTER.
DIFFICULT CALL ON FOG/STRATUS OVERNIGHT. FORECAST SOUNDINGS WOULD
SAY LITTLE IF ANY FOG/STRATUS OVERNIGHT WITH JUST SOME VERY SHALLOW
MOISTURE BELOW 950MB. SURFACE GRADIENT WILL BE SOMEWHAT STRONGER
THAN LAST NIGHT BUT WITH RIDGING ALOFT AND BOUNDARY LAYER MOISTURE
FROM MELTED SNOW...WE STILL COULD SEE SOME RE-DEVELOPMENT
OVERNIGHT. LIGHT S/SE LOW LEVEL FLOW WILL ADVECT SLIGHTLY HIGHER
DEW POINT AIR FROM LAKE HURON...AND IT APPEARS BEST CHANCE OF STRATUS
WOULD BE ACROSS THE HIGHER TERRAIN OF NORTHERN LOWER MICHIGAN
EASTWARD TOWARD LAKE HURON. EVEN WITHOUT THE STRATUS...PLENTY OF
MID/HIGH CLOUDS OVERNIGHT ASSOCIATED WITH WEAK SHORTWAVE ENERGY
SLIDING IN FROM THE WEST. ALL OF THE CLOUDS WILL KEEP TEMPERATURES
IN THE 20S FOR ALL AREAS.
JK
FRIDAY AND FRIDAY NIGHT...A COUPLE OF ITEMS OF CONCERN IN THIS
PERIOD. FOR THE MORNING...SHALLOW MOISTURE BELOW 950MB...SLIGHTLY
DEEPER DOWNWIND OF LAKE HURON WILL LEAD TO SOME LOW CLOUDS AND FOG
ACROSS THE REGION. THE DEEPER MOISTURE DOWNWIND OF LAKE HURON
WOULD CALL FOR STRATUS...WHILE OTHER AREAS WOULD TREND MORE TOWARD
FOG. FORECAST SOUNDINGS DO NOT SHOW AS MUCH DRY AIR ALOFT TO HELP
PROMOTE COOLING OF THE VERY SHALLOW MOISTURE...AND TEMPS THURSDAY
DID NOT REALLY CLIMB AS HIGH FOR ADDITIONAL SNOW MELT AND ADDED
MOISTURE TO THE BOUNDARY LAYER. WOULD STILL EXPECT PATCHY FOG TO
DEVELOP...AND WILL GO WITH THAT IDEA FOR THE MORNING. IN THE
AFTERNOON...A BAND OF DEEPER LOW LEVEL MOISTURE AHEAD OF WEAK WARM
FRONTAL SIGNATURE WILL BRING AN AXIS OF HIGHER H8 TD`S NORTHWARD
INTO NRN MICHIGAN IN THE LATE AFTERNOON. FORECAST SOUNDINGS ARE
SHOWING THIS MOISTURE ADVECTION...TO BECOME AS DEEP AS 800MB AND
WARMER THAN -5C. AREAS OF DRIZZLE STILL LOOKING GOOD...AND SEE NO
REASON TO SWAY FROM CURRENT FORECAST. PERIODS OF DRIZZLE LOOK TO
CONTINUE INTO FRIDAY NIGHT...UNDER PERSISTENT WARN ADVECTION.
TEMPERATURES TO REACH THE LOW TO MID 30S AGAIN FRIDAY...BUT AS
WARM ADVECTION/WARM FRONTAL SIGNATURE SURGES NORTH...LITTLE
NOCTURNAL DROP IN TEMPS ARE EXPECTED. SLIGHT DROP IN THE EVENING
POSSIBLE...THEN JUST INCHING UPWARD BY DAYBREAK.
SATURDAY AND SATURDAY NIGHT...SORT OF A DIFFICULT TIME FRAME FOR
THE ACTUAL WEATHER THAT WILL OCCUR...BUT IMPACTS ARE BECOMING MORE
LIKELY TO BE MINIMAL. SECONDARY SURGE OF MOISTURE ADVECTION SEEN
AT H8 MOVING INTO NRN MICHIGAN SATURDAY...WITH INITIAL FORCING
FROM UPSTREAM NRN AND SRN STREAM SHORTWAVES ARRIVING IN THE
AFTERNOON. ACTUAL MEASURABLE RAINFALL MORE LIKELY...AND WILL KEEP
70 PERCENT CHANCES. HOWEVER...IT SHOULD BE LIGHT...AND WILL JUST
CARRY PERIODS OF LIGHT RAIN...DRIZZLE AND FOG. SFC TD`S WILL BE
REACHING THE 33-35F RANGE...WHICH ARE MUCH MORE LIKELY TO RESULT
IN FOG DEVELOPMENT...ESPECIALLY OVER SNOW PACK. THE SNOW COVER
WILL TEMPER POTENTIAL WARM SFC TEMP READINGS...AND AM EXPECTING A
RATHER DREARY...DAMP AND COOL DAY WITH HIGHS IN THE 36-41 RANGE.
THIS WEATHER WILL CONTINUE THROUGH MUCH OF THE NIGHT...AS FEEL
RATHER CONFIDENT THAT TEMPS WILL STAY WARM THROUGH THE MIDNIGHT
HOUR. OVERNIGHT SATURDAY NIGHT...THE NRN AND SRN STREAM NOW
SERIOUSLY LOOK TO PHASE WITH ONE ANOTHER...AS NEARLY EVERY MODEL
SUGGESTING THIS VERY THING. ALWAYS HAVE RESERVATIONS WITH SUCH A
SCENARIO...PARTICULARLY SURROUNDING THE LOCATION OF LOW PRESSURE
DEVELOPMENT. HOWEVER...THE CONSENSUS IS FOR LOW PRESSURE TO
RAPIDLY DEVELOP/DEEPEN FROM SRN LAKE MICHIGAN UP THROUGH THE
CENTRAL AND EASTERN UPPER MICHIGAN REGION. STRONG COLD ADVECTION
BEGINS TO WRAP INTO NRN MICHIGAN FROM THE SOUTHWEST...AND ANY
DRIZZLE/LIGHT RAIN WILL CHANGE OVER TO SNOW. ALTHOUGH WOULD NOT
GET TOO CUTE WITH THIS IN THE FORECAST...WOULD SEE THE ONSET OF
THIS WITH ARRIVAL OF MID LEVEL DRY SLOT/BAND OF SNOW TRACKING
NORTHEAST ACROSS THE CWA. THAT EVOLUTION REMAINS TO BE SEEN. WILL
BRING AN ALL SNOW CHANCE TO THE SW CWA 09-12Z.
SUNDAY AND SUNDAY NIGHT...UPPER TROUGH BECOMES NEGATIVELY TILTED
AND THE SFC LOW DEEPENS AS LOW AS 986MB OR SO AS IT SHIFTS ACROSS
SE ONTARIO. WITHOUT GREAT ENOUGH CONFIDENCE IN THE EXACT TRACK OF
THE SFC LOW...DEEP WRAP AROUND MOISTURE IN DEFORMATION ZONE ON NW
FLANK OF THE SFC LOW OBVIOUSLY IN QUESTION TOO. AS IT STANDS
NOW...BEST CHANCE FOR ACCUMULATING SNOWFALL WILL RESIDE ACROSS
CENTRAL UPPER MICHIGAN AND WISCONSIN. SEVERAL INCHES OF SNOWFALL
ARE POSSIBLE THERE. ACROSS NRN MICHIGAN...THE UPPER LEVEL COLD
CORE ARRIVES...AND WE LOOK TO HAVE MORE CELLULAR/CONVECTIVE TYPE
SNOW SHOWERS WITH LAKE ENHANCEMENT. WINDS DO SHIFT DECENTLY
THROUGH THIS TIME...BUT AT LEAST A PERIOD OF RATHER VIGOROUS
SNOWFALL IS EXPECTED MOST AREAS. CONVECTIVE SNOW SHOWERS ALONE CAN
RESULT IN POOR VISIBILITY...AND WHEN COMBINED WITH STRONG AND
GUSTY WSW WINDS...CAN CERTAINLY SEE THE NEED FOR WINTER WEATHER
HEADLINES. TOMORROW MAY ANSWER THE QUESTION...AS TO WHICH HEADLINE
WE`LL NEED. ACCUMULATIONS WILL HOPEFULLY BECOME A LITTLE CLEARER
TOO. EXPECT HAZARDOUS WEATHER/DRIVING CONDITIONS ON SUNDAY...FOR
HOLIDAY TRAVELERS.
LATER PERIODS...A PERIOD OF LAKE EFFECT SNOW SHOWERS WITH NICE
CYCLONIC CONVERGENCE STILL EXPECTED ON BACKSIDE OF THIS STORM
WHICH MAY CONTINUE THROUGH MONDAY. DRY AIR FEEDS INTO THE REGION
BY MONDAY NIGHT...LIMITING SNOWFALL/ACCUMULATION POTENTIAL. MODEL
ARE ALL OVER THE PLACE HEADING INTO LATER TIME PERIODS. ONE THING
MAY BE TAKEN FROM THE PATTERN...THERE DOES NOT APPEAR TO BE ANY
MAJOR WEATHER SYSTEMS TUESDAY THROUGH THURSDAY...AT LEAST FOR
NOW.
MARINE...LOW END MARINE ISSUES TO CONTEND WITH...AS 950MB WINDS
CLIMBING TO 25 KNOTS OR SO...BUT THIS GUSTS POTENTIAL WILL BE
TEMPERED BY INCREASING STABILITY OVER THE LAKES. WENT AHEAD AND
ISSUED A SMALL CRAFT ADVISORY THROUGH FRIDAY...ALTHOUGH EXTENSIONS
MAY BE NEEDED AS 950MB WINDS CONTINUE TO INCREASE THROUGH THE
WEEKEND. STRONGER MARINE HEADLINES CERTAINLY TO BE NEEDED BY
SUNDAY AS THE COLD AIR PLOWS INTO THE REGION. SMD
AVIATION... /ISSUED 644 PM EST THU DEC 20 2007/
MID/HIGH CLOUDS ACROSS NORTHERN MI OVERNIGHT...SOME ST OVER LAKE
HURON MAY IMPACT APN THIS EVENING. CLOUD COVER AND PERSISTENT
SOUTHEAST FLOW MAY IMPACT FOG POTENTIAL AT TERMINAL SITES
OVERNIGHT. CEILINGS WILL LOWER DURING THE DAY FRIDAY... PREVAILING
MVFR CONDITIONS EXPECTED. SOME DRIZZLE OR LIGHT RAIN POSSIBLE
DURING THE AFTERNOON.
JPB
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY FROM 5 AM TO 6 PM EST FRIDAY FOR LMZ341.
LH...SMALL CRAFT ADVISORY FROM 5 AM TO 6 PM EST FRIDAY FOR LHZ346.
LS...SMALL CRAFT ADVISORY FROM 1 AM TO 6 PM EST FRIDAY FOR LSZ321.
&&
$$
AREA FORECAST DISCUSSION
NWS GAYLORD MI
1030 AM EST WED DEC 19 2007
.UPDATE....12Z SURFACE/RAOB/RUC ANALYSIS AND IR/WV/RADAR IMAGERY
SHOW A SHORTWAVE AND ASSOCIATED SURFACE LOW MOVING ACROSS NE
LOWER...A COLD FRONT EXTENDING FROM THIS LOW SOUTH TOWARDS
LANSING...AND A SURFACE TROUGH EXTENDED NW TOWARDS MQT. LIGHT
RADAR RETURNS CONTINUE TO MOVE SE ON THE WESTERN FLANK OF THE
SURFACE LOW...ENHANCED A BIT BY THE AFOREMENTIONED SURFACE TROUGH.
NUMEROUS LOCATIONS ARE STILL REPORTING LIGHT FREEZING
DRIZZLE...MIXED WITH FLURRIES OR LIGHT SNOW AT TIMES ACROSS
NORTHERN LOWER...AND THE 12Z APX SOUNDING SUGGESTS WHY WITH THE
MOISTURE DEPTH ONLY REACHING UP TO -11C. ACARS SOUNDING OUT OF
KINROSS SHOWS DEEPER MOISTURE UP TO -15C WHICH EXPLAINS ALL SNOW
BEING REPORTED ACROSS EASTERN UPPER. NW WINDS BEHIND THE LOW ARE
FUNNELING IN SLIGHTLY COOLER 850MB TEMPS THAN THE MODELS
PORTRAY...GIVING RISE TO POTENTIAL LAKE EFFECT PRECIP HEADING INTO
THE AFTERNOON. BUT FIRST...HAVE TO DEAL WITH TIMING OF NUISANT
-FZDZ COMING TO AN END.
MAIN AREA OF -FZDZ MIXED WITH LIGHT SNOW WILL CONTINUE SOUTH ACROSS
THE CWA THROUGH EARLY AFTERNOON. EXIT TIMING BASED ON RADAR AND
SATELLITE LOOPS IS AROUND 18Z ACROSS THE FAR SE CWA...BUT THERE MAY
BE SOME LINGERING FZDZ BASED ON LOWER VSBYS ACROSS THE TIP OF THE
MITT SO HAVE EXTENDED WINTER WEATHER ADVISORY THROUGH 19Z. ALTHOUGH
THE PRIMARY ROADS ARE PROBABLY OK BY NOW...UNTREATED SECONDARY ROADS
MAY STILL BE A LITTLE ICY. THEREAFTER...NW FLOW BECOMES
ESTABLISHED (ALREADY TAKING SHAPE ACROSS LAKE SUPERIOR) WITH
MARGINAL DELTA T/S AROUND 13-14C AND EXPECT A TRANSITION TO LIGHT NW
FLOW LAKE EFFECT FROM MID-AFTERNOON ONWARD. INSTABILITY IS ONLY
MARGINAL...SO ACCUMULATIONS SHOULD BE A HALF INCH OR LESS...WHICH
THE CURRENT FORECAST DISPLAYS WELL. CLOUD COVER WILL REMAIN
CLOUDY ALL DAY...AND TEMPERATURES THEREFORE WILL NOT INCREASE TOO
MUCH. SO HIGHS IN THE LOW-MID 30S LOOKS GOOD.
MPC
&&
.AVIATION... /ISSUED 632 AM EST WED DEC 19 2007/
ABUNDANT LOW LEVEL MOISTURE ASSOCIATED WITH WEAK SURFACE
LOW PRESSURE MOVING ACROSS FAR NORTHERN LOWER MICHIGAN EARLY THIS
MORNING IS RESULTING IN LOW END MVFR CIGS AND VISIBILITIES IN BR AND
LIGHT FREEZING DRIZZLE AT TVC AND APN AND FREEZING DRIZZLE AND SNOW
AT PLN. EXPECT THESE CONDITIONS TO PERSIST THROUGH MUCH OF THIS
MORNING UNTIL SLIGHTLY DRIER AIR FILTERING INTO THE REGION HELPS PUT
AN END TO THE FREEZING DRIZZLE. HOWEVER...LIGHT LAKE EFFECT SNOW
SHOWERS ARE EXPECTED TO DEVELOP THIS AFTERNOON...BUT MUCH OF THIS
ACTIVITY WILL FALL BETWEEN TAF SITES. WINDS WILL PICK UP OUT OF THE
NORTHWEST LATER THIS MORNING INTO THIS AFTERNOON BUT DIMINISH THIS
EVENING.
AJS
&&
DISCUSSION...ISSUED 510 AM
ON THE LATEST SURFACE WEATHER MAP...1009 MB LOW PRESSURE WAS
CENTERED ACROSS NORTHERN LAKE MICHIGAN. SATELLITE LOOPS AND SURFACE
OBSERVATIONS INDICATED THAT A STRATOCU DECK HAD OVERSPREAD THE
REGION. APX RADAR CONTINUED TO SHOW 16-20 DBZ RETURNS FROM THE TIP
OF THE MITT INTO EASTERN UPPER OF THE LAST FEW HOURS. MEANWHILE...A
BROAD AREA OF 4-8 DBZ RETURNS DEVELOPED ACROSS SOUTHWEST AND SOUTH
CENTRAL COUNTIES A COUPLE OF HOURS AGO WITH A SLOW PROGRESSION TO
THE EAST. THE MAIN FORECAST CONCERNS REVOLVE AROUND EXTENT OF
FREEZING DRIZZLE AND POSSIBLE HEADLINES THIS MORNING...POPS THURSDAY
NIGHT AND HOW MUCH TO TWEAK THE DETAILS OF THE POTENTIAL MAJOR STORM
SYSTEM THIS WEEKEND.
CLIPPER AND ASSOCIATED AREA OF DIVQ WILL CONTINUE TO MOVE ACROSS FAR
NORTHERN ZONES THIS MORNING. SO FAR ONLY LIGHT SNOW (NO FREEZING
DRIZZLE) HAS BEEN REPORTED ACROSS THE TIP OF THE MITT AND EASTERN
UPPER. MEANWHILE TO THE SOUTH LIGHT RETURNS CORRESPOND TO RECENT
REPORTS OF FREEZING DRIZZLE AND DEVELOPING ICY CONDITIONS. MODEL
SOUNDINGS/CROSS SECTIONS MOISTEN UP THE COLUMN THROUGH BETWEEN -12
AND -14 C THIS MORNING WHICH WOULD MEAN THAT ANY PRECIPITATION THAT
FALLS WOULD BE IN THE FORM OF SNOW. HOWEVER...WITH THE TRACK OF THE
CLIPPER (ACROSS THE FAR NORTH) ITS HARD TO BELIEVE THAT IT WOULD
MOISTEN UP THIS MUCH SOUTH OF THE SURFACE LOW TRACK. THIS IS BORNE
OUT WITH THE INCREASING NUMBER OF FREEZING DRIZZLE REPORTS.
THEREFORE WILL ISSUE A WINTER WEATHER ADVISORY FOR THIS MORNING
ACROSS ALL ZONES IN NORTHERN LOWER WITH THE EXCEPTION OF THE COUNTIES
IN THE TIPP OF THE MITT WHERE MAINLY LIGHT SNOW IS EXPECTED. AS FAR
AS SNOW AMOUNTS ACROSS THE FAR NORTH...ONLY EXPECTING LESS THAN AN
INCH OF ACCUMULATION. WINDS VEER INTO THE NORTHWEST THIS
AFTERNOON AND OVER LAKE INSTABILITY APPEARS TO BE MARGINALLY
SUFFICIENT TO SUPPORT LIGHT LAKE EFFECT SNOW SHOWERS (LAKE-850 MB
DELTA TS INCREASE TO BETWEEN 13 TO 14) WITH 900-700 MB RH STILL 60
TO 80 PERCENT AND. SO WILL ADD IN NUMEROUS LIGHT SNOW SHOWERS WITH
AN INCH OR LESS OF ACCUMULATION INTO FAVORED NW FLOW AREAS. CLOUDS ARE
EXPECTED TO HANG IN ALL DAY WITH MODEST COLD AIR ADVECTION.
TEMPERATURES SHOULD REMAIN NEARLY STEADY OR FALL BY A COUPLE OF
DEGREES (GENERALLY AROUND 30 TO THE LOWER 30S).
TONIGHT...NAM LINGERS OVER LAKE INSTABILITY/MOISTURE WELL INTO THIS
EVENING WHILE THE GFS HAS PRONOUNCED DRYING (MEAN 900-700 MB RH <40
PERCENT) AND WARMING (850 TEMPS INCREASE BY A FEW DEGREES). AT THIS
POINT WILL GO WITH A COMPROMISE SOLUTION WITH ONLY A CHANCE OF
LIGHT LAKE EFFECT SNOW SHOWERS IN NORTHWEST FLOW AREAS THROUGH
MIDNIGHT AS MEAN SURFACE-850 MB WINDS BARELY SUPPORT ORGANIZED LAKE
EFFECT (10 KNOTS OR SO). INCREASING RIDGING/SUFFICIENT
WARMING/DRYING OVERNIGHT SHOULD PUT THE KABOSH ON ANY LINGERING
ACTIVITY. LOWS TONIGHT IN THE MIDDLE TEENS TO LOWER 20S.
THURSDAY...RIDGING AT THE SURFACE AND ALOFT FOR MUCH OF THE DAY. GFS
IS FASTER THAN THE NAM WITH MOISTURE RETURN WITH DEVELOPING SOUTHERLY
FLOW BUT THIS APPEARS TO BE A BIT QUICK. FOR NOW WILL CONTINUE WITH
PARTLY CLOUDY AND MILD CONDITIONS WITH INCREASING CLOUDINESS LATE IN
THE DAY. HIGHS IN THE MILD LOWER AND MIDDLE 30S.
THURSDAY NIGHT...WARM ADVECTION SHOULD INCREASE PER NAM/GFS LEADING
TO THICKENING CLOUD DECK. MOISTURE DEPTH IS QUESTIONABLE FOR
PRECIPITATION PRODUCTION BUT WILL ADD IN A CHANCE OF FLURRIES
OVERNIGHT. THERE EVEN COULD BE SOME FREEZING DRIZZLE ONCE AGAIN BUT
WILL LET THE DAYSHIFT TAKE A BETTER LOOK AT THAT SCENARIO DUE TO
LIMITED TIME CONSTRAINT`S AT THE MOMENT. LOWS IN THE LOWER AND MIDDLE
20S.
FRIDAY...CONTINUED SOUTHERLY FLOW WITH DRY MID LEVELS SO A MOSTLY
CLOUDY DAY IS EXPECTED WITH HIGHS GENERALLY IN THE MIDDLE 30S.
FRIDAY NIGHT THROUGH SUNDAY...COMPLEX WEATHER SITUATION SHAPING UP
WITH ENERGY IN THE SOUTHERN JET STREAM MOVING NORTHEAST OUT OF THE
DESERT SOUTHWEST WHILE ENERGY IN THE NORTHERN JET STREAM DROPS DOWN
OUT OF CENTRAL CANADA. EXTENDED MODELS THIS RUN ARE IN BETTER
AGREEMENT THAT THE SOUTHERN ENERGY IMPACTS THE AREA FIRST WITH LOW
PRESSURE MOVING BY TO OUR WEST WHICH WOULD LEAD TO MAINLY RAIN FOR
SATURDAY. THE NORTHERN STREAM ENERGY IS SHOWN TO BE VERY IMPRESSIVE
AND IT MERGES WITH THE SOUTHERN STREAM ENERGY SATURDAY NIGHT INTO
SUNDAY WHICH WOULD LEAD TO FALLING TEMPERATURES...INCREASING WINDS
AND RAIN CHANGING TO SNOW SATURDAY NIGHT AND CONTINUING INTO SUNDAY.
MODELS HAVE BEEN WAVERING OVER THE DETAILS OVER THE LAST COUPLE OF
DAYS BUT WILL MAKE A FEW ADJUSTMENTS TO CURRENT FORECAST WHICH LINE
UP WITH SURROUNDING OFFICES...LIKE INCREASING POPS AND GOING WITH A
CHANGEOVER TO ALL SNOW SATURDAY NIGHT INTO SUNDAY.
SULLIVAN
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...WINTER WEATHER ADVISORY UNTIL 2 PM EST THIS AFTERNOON FOR
MIZ019>036-041-042.
LM...NONE.
LH...NONE.
LS...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
816 PM CST THU DEC 20 2007
.UPDATE...ISSUED ZR ADVISORY. RADAR INDICATING HEAVIER RETURNS
MOVING INTO AREA WITH TEMPS BELOW FREEZING. ISW REPORTED .04 RAIN SO
FAR. STILL SOME DRY AIR TO OVERCOME ON EVENING SOUNDING...SO
EXPECT AMOUNTS WILL BE LIGHTER TO THE EAST. MARATHON COUNTY
REPORTED CARS IN DITCH WITH ICE FORMING ON CARS.
TE
&&
.PREV DISCUSSION...ISSUED AT 344 PM CST THU DEC 20 2007...
SHORT TERM...TONIGHT THROUGH FRIDAY. JET ENERGY MOVING THROUGH
THE SOUTHWEST UPPER FLOW WILL PRODUCE SOME LIGHT PRECIPITATION
TONIGHT AND FRIDAY. PRECIPITATION TYPE WILL BE TRICKY TONIGHT IN
THE EASTERN PART OF THE FORECAST AREA WHERE TEMPERATURES WERE IN
THE MIDDLE TO UPPER 30S LATE THIS AFTERNOON AND DEWPOINTS WERE
JUST BELOW FREEZING. TIME OF YEAR WOULD ARGUE THAT TEMPERATURES
WILL FALL BELOW FREEZING...DESPITE WIND OFF LAKE AND A WELL MIXED
BOUNDARY LAYER. THINKING THAT THERE WILL BE FREEZING DRIZZLE AND
PERHAPS SOME LIGHT FREEZING RAIN ARRIVING LATE THIS EVENING AND
CONTINUING OFF AND ON THROUGH PART OF FRIDAY. EVEN IF AIR
TEMPERATURES ARE A DEGREE OR TWO ABOVE FREEZING THE GROUND IS
SUBFREEZING FROM THE RECENT COLD WEATHER AND WE MAY GET ICE ON
ROADS AND SIDEWALKS ANYWAY. TEMPERATURES SHOULD GET ABOVE FREEZING
EVERYWHERE BY FRIDAY AFTERNOON. WILL NOT ISSUE ANY ADVISORIES FOR
THE FREEZING DRIZZLE RIGHT NOW...BUT WILL HIGHLIGHT IN HAZARDOUS
WEATHER OUTLOOK AND INFORM EVENING SHIFT ABOUT ICING POTENTIAL.
LONG TERM...FRIDAY NIGHT THROUGH NEXT THURSDAY
MAIN FOCUS ON THIS PERIOD WILL BE WINTER STORM THAT WILL AFFECT
THE AREA SATURDAY AFTERNOON INTO SUNDAY. MODELS IN FAIR AGREEMENT
WITH BRINGING SURFACE WAVE FROM SOUTHEAST MISSOURI AT 12Z SATURDAY
MORNING INTO THE WESTERN GREAT LAKES REGION BY SUNDAY MORNING.
THE DIFFERENCE ARISE IN THE DETAILS AND STRENGTH OF THE SYSTEM.
FOR FRIDAY NIGHT...THINK THERE WILL BE PATCHY FREEZING DRIZZLE
OR LIGHT SNOW OVER THE FAR NORTH WITH A PATCHY DRIZZLE OR LIGHT
RAIN OVER THE SOUTHEAST. MINIMUM TEMPERATURES WILL ONLY DROP A
FEW DEGREES FROM HIGHS FRIDAY AFTERNOON. ON SATURDAY...SURFACE
LOW MOVES TOWARDS THE GREAT LAKES REGION. PERSISTENT 850MB
WARM ADVECTION AND LACK OF MID LEVEL MOISTURE WILL ALLOW FOR
PRECIPITATION TO START IN THE FORM OF DRIZZLE OR LIGHT FREEZING
DRIZZLE OVER THE NORTH AND DRIZZLE OVER THE SOUTH. THE DRIZZLE
SHOULD TURN OVER TO LIGHT SNOW OR LIGHT RAIN DURING THE AFTERNOON
AS MID LEVEL MOISTURE SPREADS EASTWARD ACROSS THE AREA.
CURRENT MODEL SOUNDINGS AND 850MB TEMPERATURES SUGGEST LIGHT
SNOW OVER THE NORTH...A MIX OF RAIN AND SNOW WEST OF GREEN BAY
AND THE FOX VALLEY...AND RAIN EAST OF THERE.
MODELS DIVERGE RAPIDLY WITH INTENSITY OF THE SYSTEM AND WHEN THIS
WILL OCCUR SATURDAY NIGHT AS THE LOW IS EXPECTED TO MOVE INTO
CANADA ON SUNDAY. WRF/ECMWF/CANADIAN WOULD ALSO SUGGEST THAT
THE SURFACE LOW WOULD BE A LITTLE FURTHER WEST WITH PATH OF
SYSTEM WHICH WILL ALSO AFFECT TIMING OF PRECIPITATION CHANGING
TO ALL SNOW. HPC GUIDANCE TOOK A MIDDLE OF THE ROAD APPROACH
FOR NOW...BUT ECMWF/WRF WOULD SUGGEST THAT SNOWFALL TOTALS AND
QPF TOTALS WILL NEED TO BE RAISED IN THE NEXT FEW MODEL RUNS.
WOULD NOT BE SURPRISED IF WINTER STORM WATCHES WILL BE NEEDED
SOMEWHERE ACROSS OUR AREA LATER THIS WEEKEND. BEING THE 5TH PERIOD
AND A GREAT DEAL OF UNCERTAINTY ON HOW THIS SYSTEM WILL DEVELOP
WILL LEAD TO NO WATCHES ISSUED WITH THIS PACKAGE. WILL BEEF UP
SYSTEM IN THE HAZARDOUS WEATHER OUTLOOK.
SNOW SHOWERS WILL LINGER INTO SUNDAY AS UPPER TROUGH SWINGS
THROUGH THE AREA. HAVE INCREASED SNOW CHANCES BY 10 TO 20 PERCENT
FOR SNOW SHOWER ACTIVITY. WILL ALSO NEED TO WATCH WINDS ACROSS
DOOR COUNTY SUNDAY AFTERNOON INTO SUNDAY NIGHT...WHERE GUSTS
MAY EXCEED 40 MPH AT TIMES. HIGH PRESSURE BUILDS INTO THE
REGION LATER SUNDAY NIGHT INTO MONDAY. THE REST OF THE PERIOD
WILL BE QUIET WITH A CHANCE OF LIGHT SNOW LATER IN THE WEEK.
AVIATION...CEILINGS AND VISIBILITIES WILL LOWER TONIGHT AS LOW
LEVEL MOISTURE ARRIVES FROM THE SOUTH. IN ADDITION...FREEZING
DRIZZLE MAY PRODUCE HAZARDS TO AIRCRAFT WITHOUT DEICING EQUIPMENT.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
FREEZING RAIN ADVISORY UNTIL 6 AM CST FRIDAY FOR WIZ005-010>013-
018>021-030-031.
&&
$$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
344 PM CST THU DEC 20 2007
.SHORT TERM...TONIGHT THROUGH FRIDAY. JET ENERGY MOVING THROUGH
THE SOUTHWEST UPPER FLOW WILL PRODUCE SOME LIGHT PRECIPITATION
TONIGHT AND FRIDAY. PRECIPITATION TYPE WILL BE TRICKY TONIGHT IN
THE EASTERN PART OF THE FORECAST AREA WHERE TEMPERATURES WERE IN
THE MIDDLE TO UPPER 30S LATE THIS AFTERNOON AND DEWPOINTS WERE
JUST BELOW FREEZING. TIME OF YEAR WOULD ARGUE THAT TEMPERATURES
WILL FALL BELOW FREEZING...DESPITE WIND OFF LAKE AND A WELL MIXED
BOUNDARY LAYER. THINKING THAT THERE WILL BE FREEZING DRIZZLE AND
PERHAPS SOME LIGHT FREEZING RAIN ARRIVING LATE THIS EVENING AND
CONTINUING OFF AND ON THROUGH PART OF FRIDAY. EVEN IF AIR
TEMPERATURES ARE A DEGREE OR TWO ABOVE FREEZING THE GROUND IS
SUBFREEZING FROM THE RECENT COLD WEATHER AND WE MAY GET ICE ON
ROADS AND SIDEWALKS ANYWAY. TEMPERATURES SHOULD GET ABOVE FREEZING
EVERYWHERE BY FRIDAY AFTERNOON. WILL NOT ISSUE ANY ADVISORIES FOR
THE FREEZING DRIZZLE RIGHT NOW...BUT WILL HIGHLIGHT IN HAZARDOUS
WEATHER OUTLOOK AND INFORM EVENING SHIFT ABOUT ICING POTENTIAL.
.LONG TERM...FRIDAY NIGHT THROUGH NEXT THURSDAY
MAIN FOCUS ON THIS PERIOD WILL BE WINTER STORM THAT WILL AFFECT
THE AREA SATURDAY AFTERNOON INTO SUNDAY. MODELS IN FAIR AGREEMENT
WITH BRINGING SURFACE WAVE FROM SOUTHEAST MISSOURI AT 12Z SATURDAY
MORNING INTO THE WESTERN GREAT LAKES REGION BY SUNDAY MORNING.
THE DIFFERENCE ARISE IN THE DETAILS AND STRENGTH OF THE SYSTEM.
FOR FRIDAY NIGHT...THINK THERE WILL BE PATCHY FREEZING DRIZZLE
OR LIGHT SNOW OVER THE FAR NORTH WITH A PATCHY DRIZZLE OR LIGHT
RAIN OVER THE SOUTHEAST. MINIMUM TEMPERATURES WILL ONLY DROP A
FEW DEGREES FROM HIGHS FRIDAY AFTERNOON. ON SATURDAY...SURFACE
LOW MOVES TOWARDS THE GREAT LAKES REGION. PERSISTENT 850MB
WARM ADVECTION AND LACK OF MID LEVEL MOISTURE WILL ALLOW FOR
PRECIPITATION TO START IN THE FORM OF DRIZZLE OR LIGHT FREEZING
DRIZZLE OVER THE NORTH AND DRIZZLE OVER THE SOUTH. THE DRIZZLE
SHOULD TURN OVER TO LIGHT SNOW OR LIGHT RAIN DURING THE AFTERNOON
AS MID LEVEL MOISTURE SPREADS EASTWARD ACROSS THE AREA.
CURRENT MODEL SOUNDINGS AND 850MB TEMPERATURES SUGGEST LIGHT
SNOW OVER THE NORTH...A MIX OF RAIN AND SNOW WEST OF GREEN BAY
AND THE FOX VALLEY...AND RAIN EAST OF THERE.
MODELS DIVERGE RAPIDLY WITH INTENSITY OF THE SYSTEM AND WHEN THIS
WILL OCCUR SATURDAY NIGHT AS THE LOW IS EXPECTED TO MOVE INTO
CANADA ON SUNDAY. WRF/ECMWF/CANADIAN WOULD ALSO SUGGEST THAT
THE SURFACE LOW WOULD BE A LITTLE FURTHER WEST WITH PATH OF
SYSTEM WHICH WILL ALSO AFFECT TIMING OF PRECIPITATION CHANGING
TO ALL SNOW. HPC GUIDANCE TOOK A MIDDLE OF THE ROAD APPROACH
FOR NOW...BUT ECMWF/WRF WOULD SUGGEST THAT SNOWFALL TOTALS AND
QPF TOTALS WILL NEED TO BE RAISED IN THE NEXT FEW MODEL RUNS.
WOULD NOT BE SURPRISED IF WINTER STORM WATCHES WILL BE NEEDED
SOMEWHERE ACROSS OUR AREA LATER THIS WEEKEND. BEING THE 5TH PERIOD
AND A GREAT DEAL OF UNCERTAINTY ON HOW THIS SYSTEM WILL DEVELOP
WILL LEAD TO NO WATCHES ISSUED WITH THIS PACKAGE. WILL BEEF UP
SYSTEM IN THE HAZARDOUS WEATHER OUTLOOK.
SNOW SHOWERS WILL LINGER INTO SUNDAY AS UPPER TROUGH SWINGS
THROUGH THE AREA. HAVE INCREASED SNOW CHANCES BY 10 TO 20 PERCENT
FOR SNOW SHOWER ACTIVITY. WILL ALSO NEED TO WATCH WINDS ACROSS
DOOR COUNTY SUNDAY AFTERNOON INTO SUNDAY NIGHT...WHERE GUSTS
MAY EXCEED 40 MPH AT TIMES. HIGH PRESSURE BUILDS INTO THE
REGION LATER SUNDAY NIGHT INTO MONDAY. THE REST OF THE PERIOD
WILL BE QUIET WITH A CHANCE OF LIGHT SNOW LATER IN THE WEEK.
&&
.AVIATION...CEILINGS AND VISIBILITIES WILL LOWER TONIGHT AS LOW
LEVEL MOISTURE ARRIVES FROM THE SOUTH. IN ADDITION...FREEZING
DRIZZLE MAY PRODUCE HAZARDS TO AIRCRAFT WITHOUT DEICING EQUIPMENT.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
RDM/ECKBERG
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