Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 12/30/12
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
255 PM MST FRI DEC 28 2012
.SHORT TERM...LATEST WATER VAPOR AND IR LOOPS SUGGESTING A WEAK
SHORTWAVE CURRENTLY MOVING ACROSS AREA AS NOTED BY SOME CLOUD
ENHANCEMENT. HOWEVER...WEB CAMS SHOW THE LIGHT SNOW CONFINED TO
AREAS ALONG THE CONTINENTAL DIVIDE AS WELL AS ACROSS THE PARK
RANGE IN WESTERN JACKSON COUNTY. SOME GUSTY WINDS ACROSS THE
HIGHER MOUNTAINS AND OVER THE NORTHERN FOOTHILLS WITH A FEW GUSTS
AROUND 35 MPH. LATEST MODELS SHOW THE SHORTWAVE MOVING EAST OF THE
AREA DURING THE EVENING WITH THE FLOW ALOFT BECOMING MORE NORTH
NORTHWEST. CROSS SECTIONS INDICATE A DECREASE IN MOISTURE WITH
INCREASING SUBSIDENCE. SHOULD SEE MOUNTAIN SNOW COMING TO AN END
BY MIDNIGHT WITH CLEARING SKIES. WINDS TO REMAIN A BIT GUSTY INTO
THE EVENING...BEFORE DECREASING AROUND MIDNIGHT. CLEARING SKIES...
LIGHT WINDS AND SNOW COVER WILL ALLOW FOR THE DEVELOPMENT OF
INVERSIONS IN THE MOUNTAIN VALLEYS AS WELL AS LOW LYING AREAS
ACROSS THE PLAINS. THUS...SHOULD GET QUITE COLD IN THESE AREAS
OVERNIGHT WITH TEMPERATURES BELOW ZERO ESPECIALLY THE KREMMLING
AREA IN GRAND COUNTY. ON SATURDAY...UPPER LEVEL RIDGE BUILDS OVER
COLORADO WITH FLOW ALOFT BECOMING MORE WESTERLY. 7H TEMPERATURES
WARM ABOUT 6-8 DEGREES CELSIUS FROM TODAY`S READINGS. THUS SHOULD
SEE WARMER TEMPERATURES ACROSS MUCH OF THE AREA WITH MAINLY CLEAR
SKIES. HOWEVER...INVERSIONS WILL LIMIT THE WARMUP...ESPECIALLY IN
THE MOUNTAIN VALLEYS. TEMPERATURES ACROSS THE PLAINS TO BE MAINLY
IN THE 30S...WITH MID TO UPPER 20S IN THE GREELEY AREA. WINDS
ALOFT TO BE FAIRLY LIGHT...WITH SOME GUSTY WINDS POSSIBLE ACROSS
THE HIGHER RIDGES.
.LONG TERM...SOUTHWEST FLOW ALOFT WILL PREVAIL SATURDAY NIGHT AND
SUNDAY AS AN UPPER LEVEL TROUGH MOVES ONTO THE WEST COAST. THE
TROUGH WILL CONTINUE TO DIG SOUTHEAST AND BE CENTERED OVER THE
SOUTHWESTERN STATES SUNDAY NIGHT. EXPECT A COLD NIGHT IN THE
MOUNTAIN VALLEYS SATURDAY NIGHT UNDER MOSTLY CLEAR SKIES. LOWS
SHOULD DROP BELOW ZERO IN THE MOUNTAIN VALLEYS. CLOUDS WILL INCREASE
DURING THE DAY SUNDAY AS MID AND HIGH LEVEL MOISTURE INCREASE WITH
THE APPROACH OF THE UPPER LEVEL TROUGH.
STILL A LOT OF DIFFERENCES AMONG THE MODELS ON THE TRACK OF THE
UPPER LEVEL TROUGH. THE LATEST ECMWF AND NAM ARE STARTING TO NUDGE
THE TRACK MORE NORTHERLY. MEANWHILE THE GFS CONTINUES TO FAVOR A
SOUTHERLY TRACK ACROSS THE SOUTHERN ROCKIES. BECAUSE OF THIS
NORTHERLY SHIFT...WILL INCREASE POPS ACROSS THE AREA FOR SUNDAY
NIGHT AND MONDAY. WILL HAVE LIKELY POPS FOR THE MOUNTAINS NEAR AND
SOUTH OF I-70. EVEN THE SOUTHERLY TRACK OF GFS SHOWS SNOW FOR THE
CENTRAL AND SOUTHERN MOUNTAINS OF COLORADO. WILL HAVE CHANCE TO
SLIGHT CHANCE ELSEWHERE. AS THIS SYSTEM NEARS...LATER SHIFTS CAN
TREND UP OR DOWN AS THE TRACK OF THE TROUGH BECOMES MORE CLEAR.
EXPECT HIGH TEMPERATURES TO BE COOL MONDAY AND TUESDAY UNDERNEATH
THIS SYSTEM.
ONCE THE TROUGH EXITS THE REGION...QUIET WEATHER WILL PREVAIL. EVEN
THOUGH MODELS ARE SHOWING DIFFERENT UPPER LEVEL PATTERN...ALL OF THE
DIFFERENT SOLUTIONS WOULD RESULT IN COOL AND DRY CONDITIONS.
THEREFORE WILL CONTINUE WITH THE COOL AND DRY CONDITIONS CURRENTLY
IN THE FORECAST.
&&
.AVIATION...WINDS HAVE TRENDED TOWARD LIGHT EASTERLY ACROSS THE
AREA AIRPORTS. LATEST RUC AND HRRR INDICATING WINDS TO BECOME
NORTHWEST BY 00Z...THEN SOUTHWESTERLY BY 03Z AS DRAINAGE FLOW
DEVELOPS. THIS TREND SEEMS REASONABLE THOUGH THE DIRECTION WILL BE
MORE WESTERLY AT BJC. ON SATURDAY...MODELS HINT AT A WEAK CYCLONE
DEVELOPING NORTH OF THE DENVER AREA BY 18Z. THUS...LIGHT SOUTHERLY
WINDS SHOULD PREVAIL AT THE AREA AIRPORTS THROUGH THE DAY...
PERHAPS MORE SOUTHEAST AT DEN. VFR TO CONTINUE WITH UNLIMITED
CEILINGS.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....MEIER
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
953 AM MST FRI DEC 28 2012
.UPDATE...
&&
.SHORT TERM...WEB CAMS ACROSS MOUNTAINS SHOWING AREAS OF LIGHT
SNOW ALONG THE CONTINENTAL DIVIDE OF SUMMIT AND GRAND COUNTIES.
SNOW ALSO OCCURRING IN THE STEAMBOAT AREA ON THE UPSLOPE SIDE OF
THE PARK RANGE. LATEST MODELS HINT AT A WEAK DISTURBANCE MOVING
ACROSS THE AREA THIS AFTERNOON AS THERE IS A BIT OF ASCENT NOTED
ON THE QG VERTICAL VELOCITY PROGS. LATEST RAP/RUC KEEPS FAIRLY
DEEP MOISTURE THROUGH THE DAY ALONG WITH FAVORABLE OROGRAPHICS.
AT THIS TIME...IT`S HARD TO FIND ANY TYPE OF DISTURBANCE IN THE
CURRENT SATELLITE LOOPS. WILL CONTINUE WITH THE CHANCE OF SNOW
FOR THE THE MOUNTAINS THIS AFTERNOON DUE TO THE FAVORED
OROGRAHICS. MOISTURE DECREASES THIS EVENING...SHOULD SEE SNOW
ENDING BY MIDNIGHT. ELSEWHERE...DRY CONDITIONS TO PREVAIL. OVERALL
CURRENT FORECASTS LOOKING ON TRACK WITH SOME MINOR ADJUSTMENTS FOR
CURRENT CONDITIONS. WINDS LOOK TO INCREASE ACROSS MOUNTAINS AND
HIGHER FOOTHILLS BY THE EVENING...STAYING BELOW HIGH WIND
CRITERIA.
.AVIATION...CURRENT FORECAST TRENDS LOOK REASONABLE. MAY NEED TO
INCLUDE A BROKEN DECK AROUND 7000 FEET AGL FOR AN HOUR OR SO AS
SATELLITE SHOWING A BATCH OF CLOUDS CURRENTLY MOVING ACROSS THE
DENVER AREA. BY 19Z...THIS BATCH OF CLOUDS SHOULD BE WELL
SOUTHEAST OF THE AREA. LATEST HRRR AND RAP/RUC CONTINUE TO SHOW
WINDS SHIFTING TO THE NORTHWEST BY 20Z...THEN BACK TO SOUTHWEST BY
03Z. THIS TREND STILL LOOKING REASONABLE.
&&
.PREV DISCUSSION... /ISSUED 332 AM MST FRI DEC 28 2012/
SHORT TERM...NW FLOW ALOFT WILL BE OVER THE AREA AS A DISTURBANCE
MOVES ACROSS THE MTNS THIS AFTN. OVERALL MOISTURE DEPTH IN THE
MTNS IS NOT THAT DEEP HOWEVER WITH FAVORABLE OROGRAPHIC FLOW WILL
CONTINUE TO SEE SOME LIGHT SNOW. AT LOWER ELEVATIONS EXPECT DRY
CONDITIONS. HIGHS THIS AFTN WILL BE A FEW DEGREES WARMER ACROSS
NERN CO WITH READINGS IN THE MID 20S OVER THE FAR NERN PLAINS WITH
LOWER TO MID 30S NEAR DENVER. SOME GUSTY WINDS WILL OCCUR IN THE
HIGHER MTNS AND HIGHER FOOTHILLS THIS AFTN INTO THE EVENING HOURS
BUT SPEEDS WILL STAY WELL BLO HIGH WIND CRITERIA. FOR TONIGHT
MOISTURE WILL DECREASE IN THE MTNS WITH LIGHT SNOW ENDING BY
MIDNIGHT.
LONG TERM...MODELS SHOW A FAIRLY HIGH AMPLITUDE SHORT WAVE RIDGE TO
MOVE EASTWARD ACROSS COLORADO ON SATURDAY. BY SATURDAY NIGHT...
PRETTY STRONG WEST-SOUTHWESTERLY FLOW ALOFT IS PROGGED FOR THE
CWA. ON SUNDAY...STRONG SOUTHWESTERLY FLOW ALOFT IS OVER THE CWA.
IN FACT THERE IS A 150-170 KNOT JET MAXIMUM STRETCHED FROM SOUTH
CENTRAL COLORADO TO THE NORTHEAST CORNER OF THE STATE AT 00Z LATE
SUNDAY AFTERNOON. BY 12Z MONDAY MORNING...THE FLOW ALOFT IS
SOUTH- SOUTHWESTERLY AND LIGHTER AS AN UPPER TROUGH AXIS IS JUST
WEST OF THE COLORADO WESTERN BORDER. THE SYNOPTIC SCALE ENERGY IS
DOWNWARD SATURDAY...THEN UPWARD SATURDAY NIGHT THROUGH SUNDAY
NIGHT. AT 12Z MONDAY MORNING...THE MODELS AGREE PRETTY WELL ON A
FAIRLY STRONG UPWARD Q-G ASCENT OVER NORTH CENTRAL NEW MEXICO. THE
UPWARD VERTICAL VELOCITY PROGGED FOR OUR CWA IS FAIRLY WEAK AT
THAT TIME. THE PROGGED BOUNDARY LAYER FLOW FOR THE CWA THROUGH
MUCH OF THE PERIOD IS DOMINATED BY DOWNSLOPING. THERE IS SOME WEAK
UPSLOPE PROGGED SUNDAY NIGHT FOR THE PLAINS AND LOWER FOOTHILLS.
FOR MOISTURE...SATURDAY AND SATURDAY NIGHT LOOK PRETTY DRY...JUST
SOME UPPER LEVEL MOISTURE PROGGED HERE AND THERE. MOISTURE
INCREASES FROM THE WEST ON SUNDAY...ESPECIALLY DURING THE
AFTERNOON. BY SUNDAY NIGHT MOISTURE IS DEEP OVER THE MOUNTAINS AND
FOOTHILLS. THERE IS QUITE A BIT IN THE MID AND UPPER LEVELS OF THE
PLAINS AS WELL. THE QPF FIELDS START TO BRING IN MEASURABLE
PRECIPITATION TO THE MOUNTAINS BY SUNDAY AFTERNOON. THERE ARE
LIMITED AMOUNTS OVER THE MOUNTAINS AND FOOTHILLS SUNDAY NIGHT. FOR
POPS IN THE MOUNTAINS...WILL START SOME MINOR ONES UP BY SUNDAY
AFTERNOON... AND WILL GO WITH "CHANCE"S IN THE HIGH MOUNTAINS
SUNDAY NIGHT. OROGRAPHICS ARE NOT GOOD AND THE SYNOPTIC SCALE
ENERGY IS MEAGER ..BUT THERE IS PLENTY OF MOISTURE. NO POPS FOR
THE PLAINS. FOR TEMPERATURES...SATURDAY`S HIGHS ARE 2-4 C WARMER
THAN TODAY`S. SUNDAY`S HIGHS ARE SIMILAR TO SATURDAY`S. FOR THE
LATER DAYS... MONDAY THROUGH THURSDAY...THE UPPER TROUGH AXIS
MOVES INTO COLORADO ON MONDAY...BUT IT IS SLOW AND WEAKENING AND
SOMEWHAT DEVELOPING BACK INTO A MORE EAST-WEST ORIENTATION. THE
UPPER LEVEL WIND SHIFT DOESN`T GET THROUGH THE CWA UNTIL TUESDAY
NIGHT ON BOTH THE GFS AND ECMWF. BY WEDNESDAY AT 12Z...BOTH OF
THOSE MODELS HAVE AN UPPER CLOSED LOW OVER THE SOUTHERN BORDER OF
ARIZONA AND NEW MEXICO. THIS IS SLOWER THAN YESTERDAY`S 00Z MODEL
RUNS INDICATED. SO THE FLOW ALOFT ON WEDNESDAY IS NORTHERLY FOR
THE CWA. BY THURSDAY...THERE IS UPPER RIDGING OVER THE CWA...BUT
THE LOOK OF IT AND TIMING DIFFERS BETWEEN THE ECMWF AND THE GFS.
MOISTURE IS PRETTY DEEP MONDAY AND MONDAY NIGHT...MORE SO ON THE
ECMWF. THE ECMWF ALSO HAS PRETTY DEEP MOISTURE OVER THE
PLAINS...THE GFS DOES NOT. THE GFS GETS DRY AFTER THAT ALL THE WAY
THROUGH THURSDAY. THE ECMWF IS DRY LATER ON TUESDAY INTO EARLY
THURSDAY...THEN MOISTURE RETURNS...ESPECIALLY FOR THE MOUNTAINS BY
THURSDAY. SO WILL KEEP SOME POPS IN MONDAY AND MONDAY NIGHT...THEN
NOTHING AFTER THAT FOR NOW. TEMPERATURES LOOK TO STAY BELOW
SEASONAL NORMALS ALL FOUR DAYS.
AVIATION...THERE WAS SOME FOG AND LOW CLOUDS OVER WELD COUNTY
EARLY THIS MORNING WITH SOME DENSE FOG REPORTED NR BRIGHTON.
HOWEVER WEB CAMS ALONG E470 NR BRIGHTON DO NOT SHOW ANY FOG. FOR
NOW IF LOW LVL WINDS STAY SSW LOW CLOUDS AND FOG SHOULD STAY TO
THE NORTH OF THE AIRPORT. THUS WILL KEEP CONDITIONS VFR IN THE
TAF. AS FAR AS WINDS LATEST HRRR SHOWS WINDS BECOMING MORE WNW BY
EARLY AFTN AS GUSTY WINDS IN THE FOOTHILLS MIX DOWN TO THE SFC
WITH SPEEDS IN THE 10-15 MPH RANGE. BY EARLY EVENING WINDS MAY GO
MORE WLY AND THEN BACK TO SSW BY 06Z.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....RJK
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
332 AM MST FRI DEC 28 2012
.SHORT TERM...NW FLOW ALOFT WILL BE OVER THE AREA AS A DISTURBANCE
MOVES ACROSS THE MTNS THIS AFTN. OVERALL MOISTURE DEPTH IN THE
MTNS IS NOT THAT DEEP HOWEVER WITH FAVORABLE OROGRAPHIC FLOW WILL
CONTINUE TO SEE SOME LIGHT SNOW. AT LOWER ELEVATIONS EXPECT DRY
CONDITIONS. HIGHS THIS AFTN WILL BE A FEW DEGREES WARMER ACROSS
NERN CO WITH READINGS IN THE MID 20S OVER THE FAR NERN PLAINS WITH
LOWER TO MID 30S NEAR DENVER. SOME GUSTY WINDS WILL OCCUR IN THE
HIGHER MTNS AND HIGHER FOOTHILLS THIS AFTN INTO THE EVENING HOURS
BUT SPEEDS WILL STAY WELL BLO HIGH WIND CRITERIA. FOR TONIGHT
MOISTURE WILL DECREASE IN THE MTNS WITH LIGHT SNOW ENDING BY
MIDNIGHT.
.LONG TERM...MODELS SHOW A FAIRLY HIGH AMPLITUDE SHORT WAVE RIDGE TO
MOVE EASTWARD ACROSS COLORADO ON SATURDAY. BY SATURDAY NIGHT...
PRETTY STRONG WEST-SOUTHWESTERLY FLOW ALOFT IS PROGGED FOR THE
CWA. ON SUNDAY...STRONG SOUTHWESTERLY FLOW ALOFT IS OVER THE CWA.
IN FACT THERE IS A 150-170 KNOT JET MAXIMUM STRETCHED FROM SOUTH
CENTRAL COLORADO TO THE NORTHEAST CORNER OF THE STATE AT 00Z LATE
SUNDAY AFTERNOON. BY 12Z MONDAY MORNING...THE FLOW ALFOT IS SOUTH-
SOUTHWESTERLY AND LIGHTER AS AN UPPER TROUGH AXIS IS JUST WEST OF
THE COLORADO WESTERN BORDER. THE SYNOPTIC SCALE ENERGY IS DOWNWARD
SATURDAY...THEN UPWARD SATURDAY NIGHT THROUGH SUNDAY NIGHT. AT 12Z
MONDAY MORNING...THE MODELS AGREE PRETTY WELL ON A FAIRLY STRONG
UPWARD Q-G ASCENT OVER NORTH CENTRAL NEW MEXICO. THE UPWARD
VERTICAL VELOCITY PROGGED FOR OUR CWA IS FAIRLY WEAK AT THAT TIME.
THE PROGGED BOUNDARY LAYER FLOW FOR THE CWA THROUGH MUCH OF THE
PERIOD IS DOMINATED BY DOWNSLOPING. THERE IS SOME WEAK UPSLOPE
PROGGED SUNDAY NIGHT FOR THE PLAINS AND LOWER FOOTHILLS. FOR
MOISTURE...SATURDAY AND SATURDAY NIGHT LOOK PRETTY DRY...JUST SOME
UPPER LEVEL MOISTURE PROGGED HERE AND THERE. MOISTURE INCREASES
FROM THE WEST ON SUNDAY...ESPECIALLY DURING THE AFTERNOON. BY
SUNDAY NIGHT MOISTURE IS DEEP OVER THE MOUNTAINS AND FOOTHILLS.
THERE IS QUITE A BIT IN THE MID AND UPPER LEVELS OF THE PLAINS AS
WELL. THE QPF FIELDS START TO BRING IN MEASURABLE PRECIPITATION TO
THE MOUNTAINS BY SUNDAY AFTERNOON. THERE ARE LIMITED AMOUNTS OVER
THE MOUNTAINS AND FOOTHILLS SUNDAY NIGHT. FOR POPS IN THE
MOUNTAINS...WILL START SOME MINOR ONES UP BY SUNDAY AFTERNOON...
AND WILL GO WITH "CHANCE"S IN THE HIGH MOUNTAINS SUNDAY NIGHT.
OROGRAPHICS ARE NOT GOOD AND THE SYNOPTIC SCALE ENERGY IS MEAGER
...BUT THERE IS PLENTY OF MOISTURE. NO POPS FOR THE PLAINS. FOR
TEMPERATURES...SATURDAY`S HIGHS ARE 2-4 C WARMER THAN TODAY`S.
SUNDAY`S HIGHS ARE SIMILAR TO SATURDAY`S. FOR THE LATER DAYS...
MONDAY THROUGH THURSDAY...THE UPPER TROUGH AXIS MOVES INTO
COLORADO ON MONDAY...BUT IT IS SLOW AND WEAKENING AND SOMEWHAT
DEVELOPING BACK INTO A MORE EAST-WEST ORIENTATION. THE UPPER LEVEL
WIND SHIFT DOESN`T GET THROUGH THE CWA UNTIL TUESDAY NIGHT ON BOTH
THE GFS AND ECMWF. BY WEDNESDAY AT 12Z...BOTH OF THOSE MODELS HAVE
AN UPPER CLOSED LOW OVER THE SOUTHERN BORDER OF ARIZONA AND NEW
MEXICO. THIS IS SLOWER THAN YESTERDAY`S 00Z MODEL RUNS INDICATED.
SO THE FLOW ALOFT ON WEDNESDAY IS NORTHERLY FOR THE CWA. BY
THURSDAY...THERE IS UPPER RIDGING OVER THE CWA...BUT THE LOOK OF
IT AND TIMING DIFFERS BETWEEN THE ECMWF AND THE GFS. MOISTURE IS
PRETTY DEEP MONDAY AND MONDAY NIGHT...MORE SO ON THE ECMWF. THE
ECMWF ALSO HAS PRETTY DEEP MOISTURE OVER THE PLAINS...THE GFS DOES
NOT. THE GFS GETS DRY AFTER THAT ALL THE WAY THROUGH THURSDAY. THE
ECMWF IS DRY LATER ON TUESDAY INTO EARLY THURSDAY...THEN MOISTURE
RETURNS...ESPECIALLY FOR THE MOUNTAINS BY THURSDAY. SO WILL KEEP
SOME POPS IN MONDAY AND MONDAY NIGHT...THEN NOTHING AFTER THAT FOR
NOW. TEMPERATURES LOOK TO STAY BELOW SEASONAL NORMALS ALL FOUR
DAYS.
&&
.AVIATION...THERE WAS SOME FOG AND LOW CLOUDS OVER WELD COUNTY
EARLY THIS MORNING WITH SOME DENSE FOG REPORTED NR BRIGHTON.
HOWEVER WEB CAMS ALONG E470 NR BRIGHTON DO NOT SHOW ANY FOG. FOR
NOW IF LOW LVL WINDS STAY SSW LOW CLOUDS AND FOG SHOULD STAY TO
THE NORTH OF THE AIRPORT. THUS WILL KEEP CONDITIONS VFR IN THE
TAF. AS FAR AS WINDS LATEST HRRR SHOWS WINDS BECOMING MORE WNW BY
EARLY AFTN AS GUSTY WINDS IN THE FOOTHILLS MIX DOWN TO THE SFC
WITH SPEEDS IN THE 10-15 MPH RANGE. BY EARLY EVENING WINDS MAY GO
MORE WLY AND THEN BACK TO SSW BY 06Z.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...RPK
LONG TERM....RJK
AVIATION...RPK
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1215 AM MST FRI DEC 28 2012
.UPDATE...
ISSUED AT 945 PM MST THU DEC 27 2012
MOSTLY LIGHT SNOW CONTINUES TO FALL OVER THE REGION FOR ONE MORE
NIGHT AND INTO FRIDAY BEFORE THIS STORM CYCLE COMES TO AN END.
CHECKING SNOTEL SITES AT 8 PM THE NORTHERN AND SOUTHERN MTNS HAVE
BOTH RECEIVED GENERALLY 6-8 INCHES WITHIN THE LAST 24 HOURS. THERE
WERE SOME BIG OUTLIERS IN THE NORTHERN MTNS: RIPPLE CREEK IN THE
FLATTOPS 15 INCHES...TOWER SITE NEAR STEAMBOAT MTN 17 INCHES. THE
CENTRAL MTNS HAVE RECEIVED LESS...MORE LIKE 4-6 INCHES. LIGHT
SNOWFALL ALL DAY AT POWDERHORN...OBSERVED BY SKIING FORECASTERS...
DID NOT YIELD MUCH ACCUMULATION.
AT THE RADAR TRANSMITTER ON THE GRAND MESA VAD WINDS SHOW A STRONG
VEERING FROM WEST TO NNW BEGINNING AT 00Z. SATELLITE AND MODELS
INDICATE THIS BOUNDARY IS INTO THE SAN JUANS AT 9 PM AND WILL PUSH
INTO NEW MEXICO BEFORE MIDNIGHT. THIS WILL SHIFT SNOW ACCUMULATION
EMPHASIS TO NORTH-FACING SLOPES.
HIGHLIGHTS FOR NORTHERN VALLEYS AND UTAH MOUNTAINS END AT
MIDNIGHT. THE FLY IN THAT SCENARIO IS A WEAK WAVE WORKING INTO NE
UTAH AROUND MIDNIGHT AND PASSING ACROSS NW COLORADO THROUGH 6 AM.
THE 00Z NAM AND 03Z RAP SHOW ONLY LIGHT ACCUMULATIONS WITH THIS
WAVE AND THE SLC OFFICE CONFIRMS THE WAVE HAS ONLY BEEN PRODUCING
LIGHT SNOWFALL IN SE IDAHO-NORTHERN UTAH. SO WILL LET THOSE
HIGHLIGHTS EXPIRE AT MIDNIGHT BUT KEEP HIGH POPS AND LOW
ACCUMULATIONS ACROSS THE NORTH.
OTHERWISE THE EVENING MODELS ARE PRODUCING ONLY LIGHT
ACCUMULATIONS OF A FEW INCHES ON FRIDAY FOR THE NORTH SLOPES OF
THE COLORADO MTNS. FAVORABLE OROGRAPHICS ARE IN PLACE BUT MOISTURE
IS LACKING IN THIS NEW AIR MASS. COLD AIR BEGINS TO MODIFY ON THE
MTN SLOPES ON SATURDAY AS HIGH PRESSURE BUILDS IN. THE VALLEYS
WILL BE STRONGLY CAPPED.
THE NEXT CHANCE OF SNOW IS STILL TIMED FOR SUNDAY AFTERNOON
THROUGH MONDAY EVENING TO PRODUCE A WHITE NEW YEAR TO MATCH THE
WHITE CHRISTMAS PAST.
&&
UPDATE ISSUED AT 600 PM MST THU DEC 27 2012
SATELLITE INFRARED SHOWING A RIBBON OF COOLING CLOUD TOPS FROM THE
BOOKCLIFFS TO NERN COLORADO. THIS AREA OF COOLING CLOUD TOP MARKS
THE DISORGANIZED TROUGH AXIS THAT IS CURRENTLY MOVING SOUTHEAST
ACROSS THE STATE. A BROAD AREA OF LIGHT SNOW IS FALLING BENEATH
THIS CLOUD MASS AND HAVE UPDATED FORECAST GRIDS TO REFLECT THIS.
BUT AS THE EVENING PROGRESSES...THE WESTERN PART OF THE TROUGH
AXIS BECOMES MORE DISORGANIZED EVEN MORE SO TOWARD MIDNIGHT.
EXPECT THE SNOW TO DIMINISH LATE EVENING AFTER THIS "BURST" OF
EVENING SNOW. SPECIFIC HUMIDITY VALUES ARE LOW AND THEREFORE ANY
ACCUMULATIONS WILL BE ON THE LIGHT SIDE.
&&
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 257 PM MST THU DEC 27 2012
A COLD UPPER TROUGH WAS SLOWLY SWINGING ACROSS THE FORECAST AREA
THIS AFTERNOON. A DEFORMATION/SHEAR AXIS NEAR THE SRN WY BORDER AT
MIDDAY TRAILED AN UPPER LOW EJECTING OUT ACROSS SD/NE. THIS AXIS
WAS WEAKENING PER WARMING CLOUD TOPS AND SHOULD CONTINUE TO DO SO
AS IT ROTATES SOUTHEAST ACROSS WRN CO.
THE DEFORMATION AXIS AND WEAK NW OROGRAPHIC FLOW KEPT LIGHT
SNOW ACROSS THE NORTH THROUGH MIDDAY...WITH THE LIGHT SNOW EXPANDING
ACROSS THE CENTRAL THE SOUTHERN MOUNTAINS THIS AFTERNOON AND TONIGHT
AS THE ENTIRE COLD TROUGH EVENTUALLY ROTATES THROUGH. THE ACTUAL
AMOUNT OF MOISTURE AMOUNT IN THE AIR IS LIMITED...BUT WITH THE AIR
MASS SO MOIST IT SHOULD NOT TAKE MUCH TO SQUEEZE OUT SOME SNOW. SNOW
TO WATER RATIO OF ABOUT 20:1 WAS OBSERVED ACROSS THE NORTH THIS
MORNING. WITH ANOTHER ANOTHER 1-3 INCHES OF ACCUMULATION FORECAST IN
THE MTNS TONIGHT FROM PERIODS OF SNOW...WILL CONTINUE WITH THE
CURRENT WINTER WEATHER ADVISORIES AND LET THE EVENING SHIFT
RE-EVALUATE FOR ANY EARLY CANCELLATIONS. WEST AND NORTH FACING
SLOPES WILL BE THE FAVORED AREAS TONIGHT. OUTSIDE OF THE NW CO PLATEAU...
SCATTERED SNOW SHOWERS WILL PERSIST IN THE VALLEYS BUT WITH LITTLE
ACCUMULATION. WILL INCLUDE A MENTION OF FOG IN MOST VALLEYS
TONIGHT AS WELL.
LIGHT SNOW WILL DIMINISH ACROSS THE CENTRAL AND SOUTHERN MTNS EARLY
FRIDAY MORNING...WHILE NW FLOW AND A FINAL EMBEDDED WAVE MAY KEEP
SOME LIGHT SNOW ACROSS THE NRN MTNS INTO EARLY AFTERNOON.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 257 PM MST THU DEC 27 2012
LOOK FOR A QUIETER WEATHER PATTERN THROUGH THE END OF THE WEEK AS A
SHORTWAVE RIDGE PASSES OVER THE AREA FRI NIGHT INTO SAT. EXPECT VERY
COLD NIGHTTIME LOWS FRI NIGHT AS VALLEY INVERSIONS STRENGTHEN UNDER
MOSTLY CLEAR SKIES. BELOW NORMAL TEMPS WILL FOLLOW ON SAT AS COLD
AIR REMAINS TRAPPED IN THESE VALLEYS. HOWEVER TEMPS WILL APPROACH
NORMAL VALUES IN THE MOUNTAINS...ABOVE THE INVERSIONS.
AS THE SHORTWAVE RIDGE PASSES OVER OUR FORECAST AREA EARLY IN THE
PERIOD...A LONG WAVE TROUGH WILL DEVELOP ALONG THE WEST COAST. THE
MID RANGE MODELS HAVE BEEN IN DISAGREEMENT IN THE HANDLING OF THIS
SPLITTING TROUGH AS IT TRACKS EAST. HOWEVER THE 12Z ECMWF HAS
TRENDED MORE TOWARDS THE GFS SOLUTION. THEREFORE THERE IS A LITTLE
MORE CONFIDENCE THAT THE SOUTHERN BRANCH WILL PHASE WITH ENERGY
DROPPING OUT OF THE NORTHWEST AND INTO THE GREAT BASIN ON SUNDAY.
THIS SOLUTION BRINGS THE TROUGH ACROSS OUR AREA SUN NIGHT-MON...WITH
THE SOUTHERN HALF FAVORED DUE TO THE ENERGETIC SOUTHERN BRANCH. FOR
THIS PACKAGE...HAVE STILL KEPT POPS ON THE LOW SIDE DUE TO CONTINUED
UNCERTAINTY.
BEYOND MON...MODEL AGREEMENT DECREASES. WE DO STAY IN
NORTH-NORTHWEST FLOW AS ADDITIONAL ENERGY DROPS INTO THE MEAN TROUGH
THROUGH LATE TUE. THE ECMWF AND CANADIAN SHOW A LOW SPLITTING TO THE
SOUTHWEST. THE EC PUTS IT OVER THE 4-CORNERS EARLY TUE...WITH THE
CANADIAN OVER THE AZ/UT/NV TRIPLE POINT. BY EARLY WED BOTH SOLUTIONS
SHOW THIS SPLIT-OFF LOW OVER SOUTHERN AZ...WITH OUR FORECAST AREA
BETWEEN THE LOW AND A NORTHERN BRANCH TROUGH. THE GFS SOLUTION IS
MUCH LESS SPLIT...WITH A LESS AMPLIFIED NORTHERN BRANCH AS WELL.
THESE PERIODS WILL GENERALLY BE ON THE DRY SIDE. HOWEVER CONFIDENCE
IS LOW. THIS LACK OF CONFIDENCE FOLLOWS FOR THU AS THE MID RANGE
MODELS CONTINUE TO HAVE PROBLEMS IN A GENERALLY ACTIVE AND
COMPLICATED LARGE SCALE PATTERN.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 945 PM MST THU DEC 27 2012
SNOWFALL WILL CONTINUE TO RESULT IN WIDESPREAD MOUNTAIN OBSCURATIONS
THROUGH TONIGHT. THE EXCEPTION WILL BE OVER THE EASTERN UT MOUNTAINS
WHICH SHOULD BEGIN TO SEE IMPROVING CONDITIONS AFTER 10Z. SNOWFALL
WILL CONTINUE TO PRODUCE AREAS OF MOUNTAIN OBSCURATION IN THE
HIGHER COLORADO MOUNTAINS THROUGH FRI MORNING...WITH CONDITIONS
IMPROVING IN THE AFTERNOON.
IN THE VALLEY AREAS...SNOW WILL CONTINUE TO DIMINISH THIS EVENING.
HOWEVER THE NORTHWEST PLATEAU THROUGH THE STEAMBOAT SPRINGS AREA
WILL HOLD ON TO SNOWFALL THROUGH 12Z. THEREFORE AT TIMES MVFR OR
EVEN ISOLATED IFR CONDITIONS WILL DEVELOP IN SNOW AT THE NORTHWEST
CO AND HIGHER ELEVATION AIRPORTS THROUGH THIS EVENING. THEN
BEGINNING AROUND MIDNIGHT PATCHY FOG WILL FORM IN MOST VALLEYS. ALL
AIRPORTS MAY SEE PERIODS OF MVFR CIGS/VSBYS...WITH BRIEF PERIODS
OF IFR POSSIBLE AS A RESULT.
CONDITIONS WILL BEGIN TO IMPROVE BY MID MORNING ON FRI. HOWEVER
FOG MAY PERSIST IN SOME PRONE LOCATIONS THROUGHOUT THE
MORNING...AND THE EASTERN UINTA BASIN MAY SEE AREAS OF MVFR VSBYS
IN BR THROUGH THE AFTERNOON. OTHERWISE VFR CONDITIONS ARE EXPECTED
AT THE TAF SITES BY NOON. SOME MTN OBSCURATION WILL CONTINUE OVER
THE MTNS FROM KSBS SOUTH TO KEGE INCLUDING RABBIT EARS AND VAIL
PASSES THROUGH 21Z FRIDAY.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...WINTER WEATHER ADVISORY UNTIL 6 AM MST EARLY THIS MORNING FOR
COZ003-004-009-010-012-013-017>019.
UT...NONE.
&&
$$
UPDATE...JOE
SHORT TERM...JAD
LONG TERM...EH
AVIATION...EH+JOE
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1000 PM MST THU DEC 27 2012
.AVIATION...MAIN CONCERN CONTINUES TO BE LOW CIGS AND VIS ASSOCIATED
WITH -SN THIS EVENING AND OVERNIGHT. KCOS REMAINS IFR AND WILL LIKELY
TO REMAIN IFR THROUGH 09-12Z. CIGS MAY BRIEFLY FALL TO LIFR DURING THE
EARLY MORNING HOURS. WILL SEE GRADUAL LIFTING OF CIGS BY SUNRISE
AND SHOULD RETURN TO VFR BY 13-15Z. SOME MVFR CONDITIONS POSSIBLE
AT KPUB BUT PRECIP SHOULD STAY MAINLY AWAY FROM THE TERMINAL SO HAVE
IMPROVED CONDITIONS FOR THE KPUB TAF THIS MORN. KALS ALSO A BIT TRICKY
THIS MORN...WITH THE POTENTIAL FOR PC FG OR BR GIVEN THE MOIST SURFACE
AND LIGHT WINDS. CONDITIONS SOMEWHAT FAVORABLE FOR THIS THROUGH
12-14Z SO WILL RETAIN MENTION OF REDUCED VIS FOR THIS TIME...HOWEVER
THERE IS STILL THE POSSIBILITY THAT KALS COULD REMAIN VFR. CONDITIONS
AT ALL SITES WILL IMPROVE IN THE MORNING...AND WILL SEE GENERALLY CLEAR
CONDITIONS BY AFTERNOON AND EV ON FRI. ROSE
&&
.PREV DISCUSSION... /ISSUED 303 PM MST THU DEC 27 2012/
SHORT TERM...
(TONIGHT AND FRIDAY)
TRAILING TROF ACROSS THE GREAT BASIN/NRN U.S. ROCKIES WILL SHIFT
SOUTHEASTWARD ACROSS CO TONIGHT WITH ANOTHER LOBE OF ENERGY WITHIN THE
TRAILING TROF MOVING ACROSS THE REGION DURING THE EVENING HOURS.
SFC HIGH WILL CONTINUE TO SINK SOUTHWARD ACROSS THE PLAINS WITH
SHALLOW EASTERLY UPSLOPE FLOW DEVELOPING ACROSS EL PASO COUNTY.
ALTHOUGH FORCING ALOFT IS NOT TERRIBLY STRONG...12Z MODEL RUNS
DEEPLY SATURATE THE ATMOS FAIRLY QUICKLY THIS AFTERNOON AS MOISTURE
MOVES IN FROM THE NW AND UPSLOPE HELPS SATURATE THE LOW LEVELS.
GFS...NAM12...RAP13...AND SREF ALL SPREAD LIGHT SNOW EASTWARD ACROSS
NRN SECTIONS OF THE SE MTNS/PLAINS THIS EVENING...NAMELY THE PIKES
PEAK REGION. THERE IS SOME INSTABILITY TO WORK WITH AS WELL
ESPECIALLY THIS AFTERNOON/EARLY EVENING. SO AS WEAK FORCING MOVES IN
AND SHALLOW UPSLOPE DEVELOPS...EXPECT -SHSN BANDS TO BREAK OUT
ACROSS PIKES PEAK AND EL PASO COUNTY DURING THE LATE AFTN/EARLY
EVENING AND STREAK OFF TO THE SOUTHEAST. COULD SEE LOCAL SNOW
ACCUMS OF AN INCH OR TWO FROM SOME OF THESE BANDS...AND RECENT
RUNS OF THE HRRR AND LOCAL 4 KM WRF HAVE STARTED TO TREND TOWARDS
THE OTHER MODELS IN DEPICTING THIS. THUS HAVE INCREASED POPS INTO
THE SCATTERED AND EVEN LOW LIKELY CATEGORY FOR TELLER/NRN EL PASO
COUNTIES THIS EVENING. RUC13 AND LOCAL 4 KM WRF SPREAD PCPN EASTWARD
ACROSS NRN PORTIONS OF THE SE PLAINS OUT TOWARDS KIOWA COUNTY DURING
THE OVERNIGHT HOURS. THUS WILL SPREAD AT LEAST SOME ISOLATED POPS
TO THE SOUTH AND EAST WITH TIME. NOT MUCH ACCUMULATION IS EXPECTED
FARTHER TO THE SOUTH AND EAST.
SYSTEM CLEARS THE AREA BY FRIDAY MORNING WITH DRIER AIR MOVING
IN...THOUGH THERE IS STILL ENOUGH MOISTURE IN NW FLOW TO KEEP SOME
OROGRAPHIC SNOW SHOWERS CONTINUING ALONG THE WESTERN SLOPES OF THE
MOSQUITO AND SAWATCH RANGES THROUGH THE DAY. OTHERWISE...COLD NW
FLOW REMAINS ACROSS THE AREA FOR FRIDAY...TEMPS WILL PROBABLY ONLY
WARM INTO THE 20S ACROSS THE PLAINS...WITH SFC INVERSIONS HOLDING
STRONG IN THE SAN LUIS VALLEY WHERE HIGHS WILL ONLY CLIMB INTO THE
TEENS. -KT
LONG TERM...
(SATURDAY - THURSDAY)
..ANOTHER SYSTEM FOR MONDAY...
SATURDAY INTO SUNDAY...
A SHARP SHORT WAVE RIDGE WILL MOVE ACROSS THE REGION DURING THE
WEEKEND. ANY SNOW SHOWERS OVER THE C MTNS FRIDAY EVENING WILL
QUICKLY END...AND DRY WEATHER WILL BE OVER THE REGION LATER FRIDAY
NIGHT THROUGH SUNDAY DAY. MAX TEMPERATURES SAT AND SUN WILL BE
SEASONABLE WITH TEMPS AROUND 40F PLAINS AND 20S AND 30S MTNS/VALLEYS.
LATE SUNDAY INTO TUESDAY...
ANOTHER PACIFIC NW WX SYSTEM WILL MOVE ACROSS THE REGION THROUGH
THIS PERIOD. THERE IS DISAGREEMENT AMONGST THE LONGER RANGE
GUIDANCE...BUT IT IS LIKELY THAT ANOTHER TROUGH WILL MOVE ACROSS THE
REGION DURING THIS PERIOD. THE EC IS MOST PROMISING FOR OVERALL
PRECIP ACROSS THE AREA...WITH THE GFS SHOWING MOST OF THE PRECIP
MAINLY OVER THE MTNS. COOLER WEATHER WILL ONCE AGAIN MOVE INTO THE
REGION WITH HIGHS LIKELY NOT GETTING ABOVE FREEZING MONDAY AND
TUESDAY. FOR NOW...PAINTED HIGH END SCATTERED AMOUNTS ACROSS THE
CONTDVD...SCATTERED POPS ACROSS THE REST OF THE MTNS AND ISOLD POPS
IN THE VALLEYS. ACROSS THE PLAINS...PAINTED ISOLD POPS MAINLY ACROSS
THE FAR E PLAINS AND THE RATON MESA.
AT THIS TIME...SNOWFALL AMOUNTS SHOULD BE ON THE LIGHTER SIDE...WITH
LOW END ADVISORY AMOUNTS POSSIBLE ALONG THE CONTDVD.
WED AND THU...
IT SHOULD BE DRY ACROSS THE REGION WITH TEMPS RISING INTO THE L40S
ONCE AGAIN ACROSS THE PLAINS AND 20S MTNS/VALLEYS.
AVIATION...
LOWERING CLOUD LAYER WILL AFFECT THE TAF SITES WITH MVFR CIGS
DEVELOPING IN KCOS BY 23Z. CIGS COULD EVEN FALL INTO THE IFR
CATEGORY AFTER 00Z IF -SHSN MOVES ACROSS THE TERMINAL. SNOWFALL
ACCUMULATIONS OF UP TO 1 INCH WILL BE POSSIBLE AT KCOS. KPUB WILL ALSO
SEE LOWERING CIGS IN THE EVENING...WITH MVFR TO POSSIBLY IFR CIGS
DEVELOPING AFTER 06Z WITH SOME PATCHY FOG. MAIN THREAT FOR -SHSN
LOOKS TO STAY TO THE NORTH OF THE TERMINAL...SO WILL NOT INCLUDE IT
INTO THE KPUB TAF JUST YET. ONCE SYSTEM PASSES OFF TO THE
EAST...WINDS WILL SHIFT OUT OF THE NW TO N WITH CIGS/VIS RISING INTO
THE VFR CATEGORY FOR KCOS AND KPUB AROUND/AFTER 09Z.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 11 PM MST THIS EVENING FOR COZ058-
060-066-068.
&&
$$
44/50
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
950 PM MST THU DEC 27 2012
.UPDATE...
ISSUED AT 945 PM MST THU DEC 27 2012
MOSTLY LIGHT SNOW CONTINUES TO FALL OVER THE REGION FOR ONE MORE
NIGHT AND INTO FRIDAY BEFORE THIS STORM CYCLE COMES TO AN END.
CHECKING SNOTEL SITES AT 8 PM THE NORTHERN AND SOUTHERN MTNS HAVE
BOTH RECEIVED GENERALLY 6-8 INCHES WITHIN THE LAST 24 HOURS. THERE
WERE SOME BIG OUTLIERS IN THE NORTHERN MTNS: RIPPLE CREEK IN THE
FLATTOPS 15 INCHES...TOWER SITE NEAR STEAMBOAT MTN 17 INCHES. THE
CENTRAL MTNS HAVE RECEIVED LESS...MORE LIKE 4-6 INCHES. LIGHT
SNOWFALL ALL DAY AT POWDERHORN...OBSERVED BY SKIING FORECASTERS...
DID NOT YIELD MUCH ACCUMULATION.
AT THE RADAR TRANSMITTER ON THE GRAND MESA VAD WINDS SHOW A STRONG
VEERING FROM WEST TO NNW BEGINNING AT 00Z. SATELLITE AND MODELS
INDICATE THIS BOUNDARY IS INTO THE SAN JUANS AT 9 PM AND WILL PUSH
INTO NEW MEXICO BEFORE MIDNIGHT. THIS WILL SHIFT SNOW ACCUMULATION
EMPHASIS TO NORTH-FACING SLOPES.
HIGHLIGHTS FOR NORTHERN VALLEYS AND UTAH MOUNTAINS END AT
MIDNIGHT. THE FLY IN THAT SCENARIO IS A WEAK WAVE WORKING INTO NE
UTAH AROUND MIDNIGHT AND PASSING ACROSS NW COLORADO THROUGH 6 AM.
THE 00Z NAM AND 03Z RAP SHOW ONLY LIGHT ACCUMULATIONS WITH THIS
WAVE AND THE SLC OFFICE CONFIRMS THE WAVE HAS ONLY BEEN PRODUCING
LIGHT SNOWFALL IN SE IDAHO-NORTHERN UTAH. SO WILL LET THOSE
HIGHLIGHTS EXPIRE AT MIDNIGHT BUT KEEP HIGH POPS AND LOW
ACCUMULATIONS ACROSS THE NORTH.
OTHERWISE THE EVENING MODELS ARE PRODUCING ONLY LIGHT
ACCUMULATIONS OF A FEW INCHES ON FRIDAY FOR THE NORTH SLOPES OF
THE COLORADO MTNS. FAVORABLE OROGRAPHICS ARE IN PLACE BUT MOISTURE
IS LACKING IN THIS NEW AIR MASS. COLD AIR BEGINS TO MODIFY ON THE
MTN SLOPES ON SATURDAY AS HIGH PRESSURE BUILDS IN. THE VALLEYS
WILL BE STRONGLY CAPPED.
THE NEXT CHANCE OF SNOW IS STILL TIMED FOR SUNDAY AFTERNOON
THROUGH MONDAY EVENING TO PRODUCE A WHITE NEW YEAR TO MATCH THE
WHITE CHRISTMAS PAST.
&&
UPDATE ISSUED AT 600 PM MST THU DEC 27 2012
SATELLITE INFRARED SHOWING A RIBBON OF COOLING CLOUD TOPS FROM THE
BOOKCLIFFS TO NERN COLORADO. THIS AREA OF COOLING CLOUD TOP MARKS
THE DISORGANIZED TROUGH AXIS THAT IS CURRENTLY MOVING SOUTHEAST
ACROSS THE STATE. A BROAD AREA OF LIGHT SNOW IS FALLING BENEATH
THIS CLOUD MASS AND HAVE UPDATED FORECAST GRIDS TO REFLECT THIS.
BUT AS THE EVENING PROGRESSES...THE WESTERN PART OF THE TROUGH
AXIS BECOMES MORE DISORGANIZED EVEN MORE SO TOWARD MIDNIGHT.
EXPECT THE SNOW TO DIMINISH LATE EVENING AFTER THIS "BURST" OF
EVENING SNOW. SPECIFIC HUMIDITY VALUES ARE LOW AND THEREFORE ANY
ACCUMULATIONS WILL BE ON THE LIGHT SIDE.
&&
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 257 PM MST THU DEC 27 2012
A COLD UPPER TROUGH WAS SLOWLY SWINGING ACROSS THE FORECAST AREA
THIS AFTERNOON. A DEFORMATION/SHEAR AXIS NEAR THE SRN WY BORDER AT
MIDDAY TRAILED AN UPPER LOW EJECTING OUT ACROSS SD/NE. THIS AXIS
WAS WEAKENING PER WARMING CLOUD TOPS AND SHOULD CONTINUE TO DO SO
AS IT ROTATES SOUTHEAST ACROSS WRN CO.
THE DEFORMATION AXIS AND WEAK NW OROGRAPHIC FLOW KEPT LIGHT
SNOW ACROSS THE NORTH THROUGH MIDDAY...WITH THE LIGHT SNOW EXPANDING
ACROSS THE CENTRAL THE SOUTHERN MOUNTAINS THIS AFTERNOON AND TONIGHT
AS THE ENTIRE COLD TROUGH EVENTUALLY ROTATES THROUGH. THE ACTUAL
AMOUNT OF MOISTURE AMOUNT IN THE AIR IS LIMITED...BUT WITH THE AIR
MASS SO MOIST IT SHOULD NOT TAKE MUCH TO SQUEEZE OUT SOME SNOW. SNOW
TO WATER RATIO OF ABOUT 20:1 WAS OBSERVED ACROSS THE NORTH THIS
MORNING. WITH ANOTHER ANOTHER 1-3 INCHES OF ACCUMULATION FORECAST IN
THE MTNS TONIGHT FROM PERIODS OF SNOW...WILL CONTINUE WITH THE
CURRENT WINTER WEATHER ADVISORIES AND LET THE EVENING SHIFT
RE-EVALUATE FOR ANY EARLY CANCELLATIONS. WEST AND NORTH FACING
SLOPES WILL BE THE FAVORED AREAS TONIGHT. OUTSIDE OF THE NW CO PLATEAU...
SCATTERED SNOW SHOWERS WILL PERSIST IN THE VALLEYS BUT WITH LITTLE
ACCUMULATION. WILL INCLUDE A MENTION OF FOG IN MOST VALLEYS
TONIGHT AS WELL.
LIGHT SNOW WILL DIMINISH ACROSS THE CENTRAL AND SOUTHERN MTNS EARLY
FRIDAY MORNING...WHILE NW FLOW AND A FINAL EMBEDDED WAVE MAY KEEP
SOME LIGHT SNOW ACROSS THE NRN MTNS INTO EARLY AFTERNOON.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 257 PM MST THU DEC 27 2012
LOOK FOR A QUIETER WEATHER PATTERN THROUGH THE END OF THE WEEK AS A
SHORTWAVE RIDGE PASSES OVER THE AREA FRI NIGHT INTO SAT. EXPECT VERY
COLD NIGHTTIME LOWS FRI NIGHT AS VALLEY INVERSIONS STRENGTHEN UNDER
MOSTLY CLEAR SKIES. BELOW NORMAL TEMPS WILL FOLLOW ON SAT AS COLD
AIR REMAINS TRAPPED IN THESE VALLEYS. HOWEVER TEMPS WILL APPROACH
NORMAL VALUES IN THE MOUNTAINS...ABOVE THE INVERSIONS.
AS THE SHORTWAVE RIDGE PASSES OVER OUR FORECAST AREA EARLY IN THE
PERIOD...A LONG WAVE TROUGH WILL DEVELOP ALONG THE WEST COAST. THE
MID RANGE MODELS HAVE BEEN IN DISAGREEMENT IN THE HANDLING OF THIS
SPLITTING TROUGH AS IT TRACKS EAST. HOWEVER THE 12Z ECMWF HAS
TRENDED MORE TOWARDS THE GFS SOLUTION. THEREFORE THERE IS A LITTLE
MORE CONFIDENCE THAT THE SOUTHERN BRANCH WILL PHASE WITH ENERGY
DROPPING OUT OF THE NORTHWEST AND INTO THE GREAT BASIN ON SUNDAY.
THIS SOLUTION BRINGS THE TROUGH ACROSS OUR AREA SUN NIGHT-MON...WITH
THE SOUTHERN HALF FAVORED DUE TO THE ENERGETIC SOUTHERN BRANCH. FOR
THIS PACKAGE...HAVE STILL KEPT POPS ON THE LOW SIDE DUE TO CONTINUED
UNCERTAINTY.
BEYOND MON...MODEL AGREEMENT DECREASES. WE DO STAY IN
NORTH-NORTHWEST FLOW AS ADDITIONAL ENERGY DROPS INTO THE MEAN TROUGH
THROUGH LATE TUE. THE ECMWF AND CANADIAN SHOW A LOW SPLITTING TO THE
SOUTHWEST. THE EC PUTS IT OVER THE 4-CORNERS EARLY TUE...WITH THE
CANADIAN OVER THE AZ/UT/NV TRIPLE POINT. BY EARLY WED BOTH SOLUTIONS
SHOW THIS SPLIT-OFF LOW OVER SOUTHERN AZ...WITH OUR FORECAST AREA
BETWEEN THE LOW AND A NORTHERN BRANCH TROUGH. THE GFS SOLUTION IS
MUCH LESS SPLIT...WITH A LESS AMPLIFIED NORTHERN BRANCH AS WELL.
THESE PERIODS WILL GENERALLY BE ON THE DRY SIDE. HOWEVER CONFIDENCE
IS LOW. THIS LACK OF CONFIDENCE FOLLOWS FOR THU AS THE MID RANGE
MODELS CONTINUE TO HAVE PROBLEMS IN A GENERALLY ACTIVE AND
COMPLICATED LARGE SCALE PATTERN.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 945 PM MST THU DEC 27 2012
SNOWFALL WILL CONTINUE TO RESULT IN WIDESPREAD MOUNTAIN OBSCURATIONS
THROUGH TONIGHT. THE EXCEPTION WILL BE OVER THE EASTERN UT MOUNTAINS
WHICH SHOULD BEGIN TO SEE IMPROVING CONDITIONS AFTER 10Z. SNOWFALL
WILL CONTINUE TO PRODUCE AREAS OF MOUNTAIN OBSCURATION IN THE
HIGHER COLORADO MOUNTAINS THROUGH FRI MORNING...WITH CONDITIONS
IMPROVING IN THE AFTERNOON.
IN THE VALLEY AREAS...SNOW WILL CONTINUE TO DIMINISH THIS EVENING.
HOWEVER THE NORTHWEST PLATEAU THROUGH THE STEAMBOAT SPRINGS AREA
WILL HOLD ON TO SNOWFALL THROUGH 12Z. THEREFORE AT TIMES MVFR OR
EVEN ISOLATED IFR CONDITIONS WILL DEVELOP IN SNOW AT THE NORTHWEST
CO AND HIGHER ELEVATION AIRPORTS THROUGH THIS EVENING. THEN
BEGINNING AROUND MIDNIGHT PATCHY FOG WILL FORM IN MOST VALLEYS. ALL
AIRPORTS MAY SEE PERIODS OF MVFR CIGS/VSBYS...WITH BRIEF PERIODS
OF IFR POSSIBLE AS A RESULT.
CONDITIONS WILL BEGIN TO IMPROVE BY MID MORNING ON FRI. HOWEVER
FOG MAY PERSIST IN SOME PRONE LOCATIONS THROUGHOUT THE
MORNING...AND THE EASTERN UINTA BASIN MAY SEE AREAS OF MVFR VSBYS
IN BR THROUGH THE AFTERNOON. OTHERWISE VFR CONDITIONS ARE EXPECTED
AT THE TAF SITES BY NOON. SOME MTN OBSCURATION WILL CONTINUE OVER
THE MTNS FROM KSBS SOUTH TO KEGE INCLUDING RABBIT EARS AND VAIL
PASSES THROUGH 21Z FRIDAY.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...WINTER WEATHER ADVISORY UNTIL MIDNIGHT MST TONIGHT FOR COZ001-
002-005.
WINTER WEATHER ADVISORY UNTIL 6 AM MST FRIDAY FOR COZ003-004-009-
010-012-013-017>019.
UT...WINTER WEATHER ADVISORY UNTIL MIDNIGHT MST TONIGHT FOR UTZ023-
025-028.
&&
$$
UPDATE...JOE
SHORT TERM...JAD
LONG TERM...EH
AVIATION...EH+JOE
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
907 PM MST THU DEC 27 2012
.UPDATE...
THE AREA WHERE A FEW SNOWBANDS WERE ABLE TO FORM MOVING SOUTH OVER
THE URBAN CORRIDOR CONTINUES TO MOVE SOUTH OVER THE AREA WITH
LITTLE ECHOES REMAINING ON RADAR. WILL LIKELY STILL SEE SOME LIGHT
SNOW OVER THE PALMER DIVIDE AND INTO LINCOLN COUNTY FOR THE NEXT
FEW HOURS. WITH CLEARING ON THE BACK OF THE SNOWBAND...NOT
SURPRISED TO SEE SOME PATCHY FOG AS RECENT SNOWFALL MOISTENED UP
THE AIR THEN CLEARING SKIES ALLOWS THE TEMPERATURE TO DROP. NOT
COMPLETELY CONFIDENT ON SOME OF THE OBSERVATIONS COMING IN WITH
FOG HOWEVER AS THE DEWPOINT SPREAD SEEMS TOO LARGE. BUT WILL STILL
ADD SOME PATCHY FOG TO THE FORECAST. MORE CLOUDS UPSTREAM AS WELL
AS WINDS EXPECTED TO BECOME DRAINAGE SHOULD LIMIT THE TIME OF FOG
TO EXIST.
AS THE ENHANCED BAND CONTINUES TO MOVE SOUTH...NOT MUCH MORE SNOW
IS EXPECTED OVER THE MOUNTAINS. THEREFORE WILL CANCEL THE
WINTER WEATHER ADVISORY FOR THE MOUNTAINS TWO HOURS AHEAD OF THE
SCHEDULED EXPIRATION TIME.
&&
.AVIATION...BESIDES SOME LIGHT FLURRIES AT BJC AND APA...SNOW IS
ENDING ACROSS THE AREA NORTH TO SOUTH. WITH SOME CLEARING ON THE
BACKSIDE...A FEW OBSERVATIONS REPORTING AREAS OF FOG. WOULD NOT BE
SURPRISED TO SEE SOME AREAS FLOATING AROUND...HOWEVER WITH
ADDITIONAL CLOUDS UPSTREAM AND EXPECTED DRAINAGE WINDS...FOG WILL
NOT BE LONG LIVED. CEILINGS SHOULD BE IMPROVING AFTER 06Z WITH
WINDS BECOMING DRAINAGE. WINDS TO REMAIN LIGHT SOUTHERLY THROUGH
FRIDAY AS DRY CONDITIONS PREVAIL.
&&
.PREV DISCUSSION... /ISSUED 341 PM MST THU DEC 27 2012/
SHORT TERM...MOUNTAIN WEB CAMS SHOWING ONGOING SNOWFALL...THOUGH
BEGINNING TO SHOW SOME SIGNS OF DECREASING. LATEST RUC KEEPS
AIRMASS FAIRLY MOIST THROUGH THE EVENING WITH FLOW BECOME MORE
NORTHWEST. HOWEVER...LAPSE RATES BEGIN DECREASING ALONG WITH
INCREASING SUBSIDENCE. THUS SHOULD SEE A GRADUAL DECREASE IN
SNOWFALL THROUGH THE EVENING WITH PERHAPS ANOTHER 2 TO 4 INCHES
DUE TO THE OROGRAPHICS. WILL KEEP THE ADVISORIES GOING THROUGH
06Z. ACROSS PLAINS...RADAR SHOWING LIGHT SNOW DEVELOPING ACROSS
PALMER DIVIDE AS WELL AS ACROSS PORTIONS OF EASTERN LARIMER AND
WESTERN WELD COUNTIES. LATEST MODELS SHOW THE SNOW PERSISTING
ACROSS THE PALMER DIVIDE AND SOUTHERN FOOTHILLS THROUGH THE
EVENING...SPREADING NORTH ALONG THE FOOTHILLS AND WESTERN SECTIONS
OF THE URBAN CORRIDOR AND EAST INTO LINCOLN COUNTY BY 05Z. WILL
CONTINUE THIS TREND FOR THE EVENING WITH THE HIGHER POPS IN THIS
AREA AS WELL AS IN EASTERN LARIMER COUNTY. ELSEWHERE ALONG THE
URBAN CORRIDOR...WILL CONTINUE WITH CHANCE POPS AS IT STILL
APPEARS MOST OF SNOW SHOULD OCCUR CLOSER TO THE FOOTHILLS. LOWER
POPS EASTWARD AWAY FROM THE FRONT RANGE. THE EASTERLY UPSLOPE
STILL LOOKING FAIRLY WEAK...STILL THINKING ACCUMULATIONS WILL BE
BELOW AN INCH THOUGH A FEW AREAS ALONG THE PALMER DIVIDE AND NEAR
THE FOOTHILLS COULD SEE A BIT MORE. AS LAPSE RATES DECREASE AFTER
06Z...SHOULD SEE SNOW CHANCES DECREASE AS WELL. WILL KEEP A
SLIGHT CHANCE OF LIGHT SNOW IN AND NEAR THE FOOTHILLS AS WELL AS
ALONG THE PALMER DIVIDE INTO LINCOLN COUNTY. ON FRIDAY...NORTHWEST
FLOW ALOFT TO CONTINUE WITH UPPER TROUGH OVER NORTHERN PLAINS.
MODEL CROSS SECTIONS SHOW FAIRLY DECENT MOISTURE ACROSS THE
MOUNTAINS...GRADUALLY DECREASING DURING THE AFTERNOON. THUS THERE
SHOULD BE AT LEAST A CHANCE OF SNOW DUE TO THE FAVORED
OROGRAPHICS. HOWEVER...QG VERTICAL VELOCITIES SHOW DOWNWARD
MOTION...WHICH WILL LIMIT THE SNOW CHANCES AS WELL AS
ACCUMULATIONS. ACROSS PLAINS...DRY CONDITIONS TO PREVAIL WITH A
DECREASE IN CLOUD COVER BY THE AFTERNOON. TEMPERATURES ONLY
EXPECTED TO WARM A FEW DEGREES FROM TODAY`S READINGS DUE TO SNOW
COVER AND INVERSIONS.
LONG TERM...DRIER AIR WILL BE MOVING OVER COLORADO FRIDAY NIGHT. IF
ANY SNOW SHOWERS LINGER INTO THE EVENING HOURS...THEY WILL BE LIGHT
AND SHORT LIVED. SKIES WILL CLEAR BY MIDNIGHT...IF NOT EARLIER. THE
CLEAR SKIES WILL ALLOW TEMPERATURES IN LOW LYING AREAS TO PLUMMET.
EXPECT THE MOUNTAIN VALLEYS TO DROP BELOW ZERO. COLD LOCATIONS LIKE
KREMMLING WILL DROP TO AROUND -20 BY SATURDAY MORNING. WEAK
DOWNSLOPE WINDS WILL DEVELOP ALONG THE FRONT RANGE. THIS WILL KEEP
THE FOOTHILLS AND AREAS CLOSE TO FOOTHILLS WARMER WITH LOWS IN THE
SINGLE DIGITS TO TEENS.
UPPER LEVEL RIDGE WILL MOVE ACROSS COLORADO SATURDAY. AIRMASS UNDER
IT WILL BE DRY RESULTING IN MOSTLY CLEAR SKIES. HIGHS WILL CLIMB
INTO THE 30S FOR MOST OF NORTHEAST COLORADO. LOW LYING AREAS MAY BE
STUCK UNDER AN INVERSION AND WILL STRUGGLE TO REACH THE 30S.
CLOUDS WILL INCREASE SUNDAY AS AN UPPER LEVEL TROUGH MOVES OVER THE
GREAT BASIN. THE MOISTURE WILL BE AT THE MID AND UPPER LEVELS OF THE
ATMOSPHERE...SO NOT EXPECTING ANY SNOW UNTIL THE TROUGH NEARS WHICH
WILL BE LATE SUNDAY NIGHT. THE UPPER LEVEL TROUGH WILL DIG SOUTHEAST
AND MOVE ACROSS THE SOUTHERN ROCKIES MONDAY. A COLD FRONT ASSOCIATED
WITH THE TROUGH WILL PUSH THROUGH THE AREA MONDAY. APPEARS THE
TROUGH WILL BE TOO FAR SOUTH TO BRING THE AREA MUCH PRECIPITATION.
WILL KEEP LOW POPS...10 TO 30 PERCENT...IN THE FORECAST FOR MONDAY
AND TUESDAY. HIGHEST POPS BEING IN THE MOUNTAINS. COOL AIR WILL MOVE
BACK INTO THE AREA FOR MONDAY AND TUESDAY.
FOR WEDNESDAY AND THURSDAY...APPEARS THERE WILL BE SOME SORT OF
RIDGE OVER THE WESTERN STATES. THIS WILL PRODUCE A DRY BUT COOL
NORTHWEST FLOW ALOFT OVER COLORADO. WILL KEEP THE FORECAST DRY WITH
TEMPERATURES AT OR SLIGHTLY BELOW NORMAL.
AVIATION...LIGHT SNOW DEVELOPING ALONG PALMER DIVIDE AS WELL AS
WESTERN AND SOUTHERN SECTIONS OF THE DENVER AREA. LATEST RUC AND
HRRR KEEPS THE BEST CHANCE FOR SNOW AT APA AND BJC THROUGH 06Z...
WILL CONTINUE THE TEMPO FOR MVFR/IFR CONDITIONS. STILL SOME CHANCE
THAT SNOW COULD SPREAD INTO DIA WITH POSSIBLE MVFR/IFR CONDITIONS.
FOR NOW WILL CONTINUE VCSH AND SEE HOW THINGS DEVELOP. SNOW
CHANCES TO DECREASE AFTER 06Z WITH VFR CONDITIONS AND IMPROVING
CEILINGS. EASTERLY WINDS TO DECREASE AFTER MIDNIGHT AND BECOME
SOUTHERLY AS DRAINAGE PATTERN DEVELOPS. WINDS TO REMAIN LIGHT
SOUTHERLY THROUGH FRIDAY AS DRY CONDITIONS PREVAIL.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....MEIER
UPDATE/AVIATION...KRIEDERMAN
AREA FORECAST DISCUSSION
NWS TAUNTON MA
1027 PM EST SAT DEC 29 2012
.SYNOPSIS...
A RAPIDLY INTENSIFYING COASTAL STORM WILL BRING A SIGNIFICANT
SNOWFALL TO MOST OF THE REGION TONIGHT. AS THE STORM EXITS
SUNDAY...DRY BUT BLUSTERY AND COLD WEATHER FOLLOWS. SEVERAL WEAK
DISTURBANCES WILL RACE ALONG THE CANADIAN BORDER NEXT WEEK. THE
DISTURBANCES COULD BRING A FEW WIDELY SCATTERED SNOW SHOWERS. ONE
ON WEDNESDAY WILL BRING MUCH COLDER THAN NORMAL TEMPERATURES FOR
THE LATTER HALF OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
1015 PM UPDATE...
MADE SIGNIFICANT CHANGES TO SNOW ACCUMULATIONS ALONG THE COASTS AS
WELL AS WITHIN A POTENT BAND FROM NORTHERN CONNECTICUT INTO
PORTIONS OF NORTHERN RHODE ISLAND. COASTAL FRONT PUSHED FARTHER
INLAND FROM PREVIOUS THINKING...PUSHING TEMPERATURES INTO THE
UPPER 30S FOR A SIGNIFICANT PORTION OF THE STORM. THUS LOWER SNOW
ACCUMULATIONS EXPECTED ALONG THE IMMEDIATE COASTS. DROPPED THE
WINTER WEATHER ADVISORIES FOR THE EASTERN AND SOUTHERN PLYMOUTH
COUNTY...AS WELL AS BARNSTABLE COUNTY AND BLOCK ISLAND.
ADJUSTED TEMPERATURES AND DEW POINTS TO REFLECT THE LATEST
OBSERVATIONS.
LATEST RAP LOOKS TO HAVE A VERY GOOD HANDLE ON THE WINDS BECOMING
NORTH AND NORTHWEST. EXPECTING ALL PRECIPITATION TO TRANSITION TO
SNOW OVER THE NEXT COUPLE OF HOURS.
PREVIOUS DISCUSSION FOLLOWS...
***A SHORT DURATION BUT HIGH IMPACT SNOWSTORM THROUGH LATE TONIGHT
AND TRAVEL IS NOT RECOMMENDED***
ALL THE INGREDIENTS ARE COMING TOGETHER FOR A SIGNIFICANT WINTER
STORM ACROSS SOUTHERN NEW ENGLAND. LOW PRESSURE WAS IN THE EARLY
STAGES OF BOMBING OFF THE VIRGINIA COAST AND HAVE NOTED SOME
LIGHTNING STRIKES OVER THE PAST HOUR. IN FACT...THE LOW PRESSURE
SYSTEM WILL UNDERGO BOMBOGENESIS DROPPING NEARLY 25 MB IN 12 HOURS!
THIS IS A CLASSIC SETUP FOR A HEAVY SNOWFALL ACROSS SOUTHERN NEW
ENGLAND. THE WORST CONDITIONS WILL PROBABLY BE FROM AROUND 5 PM
UNTIL MIDNIGHT. SO A SHORT DURATION BUT HIGH IMPACT STORM IS
EXPECTED.
GIVEN ALL THE ABOVE FACTORS...HAVE EXPANDED WINTER STORM WARNINGS
SEVERAL COUNTIES FURTHER NORTHWEST. EVEN THOUGH QPF WILL BE LOWER
ACROSS THE INTERIOR...SNOW RATIOS WILL BE HIGHER AND SHOULD BE
ENOUGH FOR MARGINAL WINTER STORM WARNING CRITERIA. SNOWFALL
ACCUMULATIONS OF 4 TO 8 INCHES ARE ANTICIPATED FROM SOUTHERN
NH/SOUTHWEST AND CENTRAL MA...AS WELL AS NORTHERN CT. THE LATEST
TRENDS OVER THE PAST 24 HOURS HAVE BEEN TO INCREASE QPF AND PLACE IT
FURTHER NORTHWEST WITH THE RAPID INTENSIFYING STORM. FEEL THAT THE
UPGRADE TO A WARNING IS THE BEST MOVE AT THIS TIME. LATEST RADAR
IMAGERY AND MESOSCALE MODELS SUPPORT THESE AMOUNTS.
THE WORST OF THE STORM LOOKS TO HIT INTERIOR RHODE ISLAND/SOUTHEAST
MA. GIVEN THE RAPID INTENSIFICATION OF THE LOW PRESSURE SYSTEM A
VERY STRONG DEFORMATION ZONE SHOULD DEVELOP. SNOW GROWTH IS QUITE
IMPRESSIVE...WITH THE NAM INDICATING 30 TO 50 MB/S OF LIFT ROUGHLY
BETWEEN 5 PM AND MIDNIGHT. THIS IS SUPPORTIVE OF 2 INCH PER HOW
SNOWFALL RATES AND CAN/T EVEN RULE OUT A CLAP OR TWO OF THUNDER. IT
APPEARS THERE SHOULD BE A SWATH OF 6 TO 12 INCHES OF SNOW ACROSS
INTERIOR RHODE ISLAND/INTERIOR SOUTHEAST MA. IT SHOULD BE COLD
ENOUGH FOR MAINLY SNOW IN THIS REGION AND MAY SEE A COASTAL FRONT
SETUP...WHICH WOULD HELP IN THE HIGHER AMOUNTS. ACROSS THE
IMMEDIATE COAST...ENOUGH OF A MARINE LAYER AND MARGINAL 925 MB
TEMPERATURES MAY SUPPORT A MIXTURE FOR A TIME THROUGH EARLY THIS
EVENING CUTTING DOWN ON ACCUMULATIONS A BIT. THE OTHER THING WILL
HAVE TO KEEP AN EYE ON IS FOR A BAND OF WET SNOW IN THIS REGION TO
RESULT IN SOME DOWNED TREE LIMBS/ISOLATED POWER OUTAGES.
ACROSS THE CAPE AND ISLANDS...IT LOOKS WARM ENOUGH FOR MUCH OF THE
PRECIPITATION TO FALL AS RAIN THROUGH EARLY EVENING. HOWEVER...AS
THE LOW BOMBS OUT THEY WILL LIKELY TURN TO A PERIOD OF SNOW
PARTICULARLY ACROSS THE UPPER CAPE. THAT IS THE BEST CHANCE FOR
SEEING SEVERAL INCHES OF SNOW. CAN/T RULE OUT A SLOPPY INCH OR SO
ACROSS THE OUTER-CAPE/NANTUCKET...BUT THAT WILL DEPEND UPON HOW MUCH
MOISTURE IS LEFT OF THE BACKSIDE.
UNCERTAINTIES... LIKE ANY WINTER STORM THERE ARE A FEW THINGS THAT
WILL NEED TO BE CLOSELY MONITORED.
(1) WE DID UPGRADE TO WINTER STORM WARNINGS ACROSS A GOOD CHUNK OF
THE INTERIOR...BASED ON THE MESOSCALE MODELS AND LATEST RADAR
IMAGERY. HOWEVER...AS THE COASTAL UNDERGOES BOMBOGENESIS IT COULD
BRING AN END TO THE SNOW EARLIER THAN ANTICIPATED ACROSS THE
INTERIOR. IF THIS OCCURS...OUR SNOWFALL AMOUNTS MAY BE OVERDONE IN
THIS AREA.
(2) THE EXACT PLACEMENT OF THE RAIN/SNOW LINE ACROSS THE FAR
SOUTHEAST NEW ENGLAND COAST IS UNCERTAIN. SNOW ACCUMULATIONS MAY
END UP HIGHER OR LOWER THAN FORECAST ALONG THE IMMEDIATE SOUTH
COAST/COASTAL PLYMOUTH COUNTY AND THE UPPER CAPE DEPENDING ON THE
EXACT THERMAL STRUCTURE. SOUNDINGS SHOW CONDITIONS BECOMING
ISOTHERMAL...SO AN HOUR OR TWO DIFFERENCE IN THE CHANGE OVER TO SNOW
WILL MAKE A BIG DIFFERENCE IN ACCUMULATIONS.
(3) EVEN HIGH RESOLUTION MODELS MAY BE OFF WITH THE EXACT PLACEMENT
OF HEAVIEST SNOW. THIS WILL DEPEND ON VERY MESOSCALE FEATURES SUCH
AS EXACT LOCATIONS OF COASTAL FRONT AND HOW FAR WEST THE INTENSE QPF
FIELD MAKES IT. THE HEAVIEST SNOWFALL COULD END UP FURTHER
NORTHWEST/SOUTHEAST THAN WE HAVE DEPICTED IN OUR FORECAST.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
SUNDAY...LEFTOVER SNOW SHOWERS AND FLURRIES SUN MORNING IN THE
MOIST CYCLONIC FLOW BEHIND DEPARTING LOW. HOWEVER INCREASING
SUNSHINE IS EXPECTED IN THE AFTERNOON AS THE COLUMN DRIES. THIS
WILL PROMOTE ADDITIONAL MIXING AS PRESSURE GRADIENT TIGHTENS
FURTHER AND H925 WINDS REACH 50 KTS. CONCERNED THAT SOME OF THESE
STRONGER WINDS WILL MIX DOWN TO THE GROUND TO PROMPT GUSTS OF
40-50 MPH. AS SUCH WILL GO WITH A WIND ADVISORY FOR CENTRAL AND
EASTERN ZONES FOR THE DAYTIME HOURS SUNDAY...THIS WILL INCLUDE AN
EXTENSION OF THE WIND ADVY FOR CAPE AND ISLANDS THAT CONTINUES TO
BE IN EFFECT FOR TONIGHT.
HIGHS ONLY IN THE UPPER 20S AND LOWER 30S EXPECTED...SO NOT A LOT
OF MELTING EXPECTED ON UNTREATED SURFACES ESPECIALLY IN THE SHADE.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
*** COLDER THAN NORMAL TEMPS ESPECIALLY MID TO LATE NEXT WEEK ***
SYNOPSIS...TREND CONTINUES TO LOOK COLDER THAN NORMAL FOR TEMPS
ESPECIALLY MID TO LATE NEXT WEEK AS POLAR VORTEX TRANSITIONS OVER
SOUTHERN QUEBEC. THIS WILL SHIFT THE STORM TRACK SOUTH OF NEW
ENGLAND AND PRECLUDE ANY LARGE QPF EVENTS FOR THE NORTHEAST.
SUNDAY NIGHT...WINDS WILL PROBABLY STILL BE GUSTY TO START BUT WITH
CLEARING SKIES ANTICIPATE DECOUPLING...WITH TEMPERATURES DROPPING
INTO THE TEENS ACROSS MUCH OF THE AREA...EXCEPT SINGLE DIGITS OVER
PORTIONS OF THE FAR INTERIOR.
MON/NEW YEARS EVE/NIGHT...CONDITIONS LOOK TO BE DRY BUT PROBABLY
NOT COMPLETELY CLOUD FREE. HIGH PRESSURE RIDGE APPEARS OVER OUR
AREA TO START BUT THEN SUPPRESSES TO OUR SOUTH. WITHIN SWIFT
MID/UPPER FLOW SHORT WAVE APPEARS TO BRING SOME CLOUDS OUR WAY AS
WELL AS APPROACH OF POLAR COLD FRONT...BUT NOT ENOUGH MOISTURE FOR
PRECIPITATION. WILL KEEP POPS TO SLIGHT CHANCE OR LOWER.
TUE...POLAR FRONT SWEEPS ACROSS THE AREA. LIMITED MOISTURE WITH THIS
BOUNDARY SO OTHER THAN SOME FLURRIES DRY WEATHER SHOULD PREVAIL.
MUCH COLDER BEHIND THE FRONT FOR LATER TUE/TUE NIGHT.
TUESDAY NIGHT-WEDNESDAY... CLIPPER LOW MOVES ACROSS THE GREAT LAKES
AND THEN CROSSES NORTHERN NEW ENGLAND...SWINGING ANOTHER COLD
FRONT ACROSS SOUTHERN NEW ENGLAND DURING WEDNESDAY. THE ECMWF
CONTINUES TO DO THIS ABOUT 6 HOURS FASTER THAN THE GFS...AND WITH
THE NEARBY STRONG UPPER JET /220 KNOTS/ THIS FASTER MOTION SEEMS
REASONABLE. EITHER WAY...EXPECT SOME CLOUDS TO DEVELOP FOR
WEDNESDAY AND POSSIBLY WIDELY SCATTERED SNOW SHOWERS. AFTER THE
COLD FRONT MOVES THROUGH...SUFFICIENT COLD ADVECTION TO PROMOTE
MIXING OF STRONGER WIND GUSTS TO THE SURFACE. WINDS ALOFT OF 25 TO
35 KNOTS ARE WITHIN RANGE FOR MIXING TO THE SURFACE AS GUSTS.
TEMPS ARE A BLEND OF HPC AND GMOS VALUES.
GOOD INSTABILITY EXPECTED OVER THE WATERS WITH 5-7C WATER TEMPS AND
AIR TEMPS -10C OR COLDER MOVING OVER THE WATERS. SMALL WIND
DIRECTION CHANGE WITH HEIGHT BUT LESS THAN 30 DEGREES. POTENTIAL
FOR OCEAN EFFECT CLOUDS/SNOW SHOWERS ESPECIALLY AFTER THE COLD FRONT
PASSES.
THURSDAY-FRIDAY...HIGH PRESSURE BUILDS OVER THE REGION. TEMPS AT
925 MB WILL BE AT -10C TO -14C...SUPPORTING MAX SURFACE TEMPS OF 15-
25F. MEANWHILE DEWPOINTS FALL TO -5F INLAND AND AROUND 10F ALONG THE
COAST...WHILE NORTHWEST WINDS DIMINISH BELOW 10 KNOTS EACH NIGHT.
BETWEEN THE COLD ADVECTION AND CLEAR/LIGHT WIND CONDITIONS...EXPECT
A COUPLE OF CHILLY NIGHTS. WE USED A BLEND OF HPC AND GMOS
VALUES FOR MIN TEMPS...AND LOWERED THEM A COUPLE OF DEGREES.
SATURDAY... ANOTHER SHORTWAVE MOVES THROUGH NORTHERN NEW ENGLAND.
GENERALLY DRY WITH DEVELOPING AFTERNOON CLOUDS ESPECIALLY NORTHERN
MASS/SOUTHERN NH.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
OVERVIEW...HIGH CONFIDENCE IN CONDITIONS TONIGHT BUT LOWER
CONFIDENCE ON EXACT TIMING. MODERATE TO HEAVY SNOWFALL WILL RESULT
IN CONDITIONS LOWERING TO LIFR TO IFR THRESHOLDS ACROSS MOST
LOCATIONS BY EARLY EVENING. THE WORST CONDITIONS WILL BE THROUGH
MIDNIGHT...WITH CONDITIONS IMPROVING THEREAFTER. MAINLY VFR
CONDITIONS ARE ANTICIPATED BY 12Z SUNDAY.
KBOS TAF...HIGH CONFIDENCE IN CONDITIONS BUT LOWER CONFIDENCE IN
EXACT TIMING.
KBDL TAF...HIGH CONFIDENCE IN CONDITIONS BUT LOWER CONFIDENCE IN
EXACT TIMING.
OUTLOOK...SUNDAY THROUGH WEDNESDAY...
FORECAST CONFIDENCE MODERATE TO HIGH FOR THIS PERIOD.
SUNDAY...ANY LEFTOVER IFR/MVFR EARLY WILL TREND TO VFR. GUSTY NNW
WINDS TO 30-40 KT.
MONDAY THROUGH THURSDAY...VFR THROUGH THE PERIOD. NORTHWEST WINDS
WEDNESDAY MAY GUST TO 30 KNOTS ESPECIALLY ALONG THE COAST.
&&
.MARINE...
HIGH CONFIDENCE TONIGHT.
STORM WARNINGS CONTINUE FOR THE EASTERN OUTER-WATERS AS COASTAL LOW
PRESSURE UNDERGOES BOMBOGENESIS. MAINLY GALE FORCE WIND GUSTS
ACROSS MOST OF THE OTHER WATERS. SEAS ARE EXPECTED TO BUILD TO
AROUND 15 FEET ACROSS THE EASTERN OUTER-WATERS LATE AND WNA GUIDANCE
IS LIKELY UNDERDONE.
OUTLOOK...SUNDAY THROUGH WEDNESDAY...
MODERATE TO HIGH CONFIDENCE THIS PERIOD.
SUNDAY INTO SUNDAY NIGHT...STORM CENTER TRACKS INTO THE MARITIMES
WITH NNW GALES ANTICIPATED ACROSS MOST OF THE NEW ENGLAND WATERS.
VSBY IMPROVES WITH PRECIP MOVING OFFSHORE.
MONDAY...DIMINISHING WIND AS STORM CENTER PULLS FURTHER NE OF OUR
AREA...BUT ROUGH SEAS LINGER ON OUTER COASTAL WATERS AND WINDS WILL
LIKELY STAY WELL INTO SCA RANGE.
TUESDAY...COULD SEE A PERIOD OF GALE FORCE GUSTS WITH INCREASING
SEAS WITH THE PASSAGE OF A POLAR FRONT TUESDAY.
TUESDAY NIGHT THROUGH THURSDAY... WINDS DIMINISH TUESDAY NIGHT.
A COLD FRONT MOVES ACROSS THE WATERS WEDNESDAY. NORTHWEST WINDS
INCREASING BEHIND THE FRONT MAY GUST TO 35 TO 40 KNOTS LATE
WEDNESDAY AND WEDNESDAY NIGHT BEFORE DIMINISHING THURSDAY. SEAS
SUBSIDE BELOW 5 FEET DURING TUESDAY NIGHT...THEN BUILD AGAIN LATE
WEDNESDAY AS NORTHWEST WINDS INCREASE BEHIND THE COLD FRONT. SEAS
WILL TOP OUT AT 5 TO 9 FEET ON THE OUTER WATERS WEDNESDAY
NIGHT...THEN SUBSIDE AGAIN ON THURSDAY.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...WIND ADVISORY FROM 7 AM TO 8 PM EST SUNDAY FOR CTZ002>004.
WINTER STORM WARNING UNTIL 7 AM EST SUNDAY FOR CTZ004.
WINTER STORM WARNING UNTIL 6 AM EST SUNDAY FOR CTZ002-003.
MA...WINTER WEATHER ADVISORY UNTIL 7 AM EST SUNDAY FOR MAZ002-003.
WIND ADVISORY FROM 7 AM TO 8 PM EST SUNDAY FOR MAZ004>007-
011>021-023-026.
WINTER STORM WARNING UNTIL 7 AM EST SUNDAY FOR MAZ005>007-
012>018-020.
WINTER STORM WARNING UNTIL 6 AM EST SUNDAY FOR MAZ004-008>011-
026.
WIND ADVISORY UNTIL 8 PM EST SUNDAY FOR MAZ022-024.
NH...WINTER WEATHER ADVISORY UNTIL 7 AM EST SUNDAY FOR NHZ011.
WINTER STORM WARNING UNTIL 6 AM EST SUNDAY FOR NHZ012-015.
RI...WIND ADVISORY FROM 7 AM TO 8 PM EST SUNDAY FOR RIZ001>008.
WINTER STORM WARNING UNTIL 7 AM EST SUNDAY FOR RIZ001>007.
MARINE...GALE WARNING UNTIL 7 PM EST SUNDAY FOR ANZ231>234-251-256.
GALE WARNING FROM 10 AM TO 7 PM EST SUNDAY FOR ANZ230-235>237.
STORM WARNING UNTIL 5 AM EST SUNDAY FOR ANZ250-254-255.
&&
$$
SYNOPSIS...FRANK
NEAR TERM...BELK/FRANK
SHORT TERM...NMB
LONG TERM...WTB/NMB
AVIATION...WTB/FRANK/NMB
MARINE...WTB/FRANK/NMB
AREA FORECAST DISCUSSION...CORRECTED
NWS TAMPA BAY RUSKIN FL
305 AM EST FRI DEC 28 2012
.SYNOPSIS...
08Z WATER VAPOR AND H4 RAP ANALYSIS SHOW AN AMPLIFIED BUT
PROGRESSIVE UPPER LEVEL PATTERN OVER THE CONUS. FROM WEST TO EAST WE
FIND NORTHERN STREAM FLOW RIDGING NORTHWARD ALONG THE PACIFIC COAST
BEFORE DIGGING BACK SOUTH INTO LONGWAVE TROUGHING EJECTING EASTWARD
FROM THE INTERMOUNTAIN WEST. FURTHER DOWNSTREAM THE FLOW THEN FORMS
LONGWAVE RIDGING OVER MUCH OF THE EASTERN STATES IN THE WAKE OF THE
SYSTEM NOW DEPARTING NEW ENGLAND TOWARD THE CANADIAN MARITIMES. THE
FL PENINSULA IS UNDER WEAK UPPER RIDGING FORCED BY THE HEIGHT FALLS
CURRENTLY SPREADING ACROSS THE SOUTHERN PLAINS. 28/00Z KTBW SOUNDING
SHOWED A VERY DRY PROFILE BELOW 500MB...BUT THIS DRY COLUMN WILL BE
SHORT-LIVED AS ALL GUIDANCE MEMBERS SHOWS A QUICK MOISTENING AND
DESCENDING OF MOISTURE WORKING SOUTH TO NORTH TODAY.
AT THE SURFACE...HIGH PRESSURE IS IN CONTROL FOR THE MORNING HOURS.
THE LIGHT WINDS AND DRY COLUMN HAVE ALLOWED FOR GOOD RADIATIONAL
COOLING...ESPECIALLY UP OVER THE NATURE COAST. TEMPERATURES WITHIN
THE FREEZE WARNING HAVE BEEN NEAR OR JUST BELOW FREEZING FOR THE
PAST COUPLE OF HOURS...AND AREAS OF DENSE RADIATIONAL GROUND FOG
HAVE DEVELOPED. THIS FOG IS LIKELY QUITE SHALLOW IN NATURE. NOT
ANTICIPATING MUCH MORE OF A TEMP DROP...AS THE ADVERTISED UPPER
LEVEL MOISTURE IS BEGINNING TO SPREAD OVER THE REGION AND SHOULD
SLOW ANY FURTHER RADIATIONAL COOLING THROUGH DAWN. SEEING THE FIRST
SIGNS OF SURFACE CYCLOGENESIS ALONG THE UPPER TX COAST IN ADVANCE OF
THE UPPER TROUGH. EXTENDING EASTWARD FROM THIS LOW...2 DIFFERENT
WARM FRONTAL FEATURES CAN BE SEEN. ONE IS HUGGING THE NORTHERN GULF
COAST...AND THE OTHER APPEARS TO BE FURTHER SOUTH. BOTH OF THESE
FEATURES WILL BE BUILDING INTO THE EASTERN GULF TODAY AND MAKE FOR A
SOMEWHAT TRICKY FORECAST.
&&
.SHORT TERM (TODAY THROUGH SUNDAY)...
TODAY/TONIGHT...AS MENTIONED ABOVE...COLUMN MOISTURE WILL BE
INCREASING AND DESCENDING WITHIN A DEVELOPING LOW LEVEL UPGLIDE/ WAA
PATTERN ALONG THE 290-305K SURFACES. SKIES WILL TRANSITION TO MOSTLY
CLOUDY FROM SOUTHWEST TO NORTHEAST. UPGLIDE/WAA AND RESULTING
MOISTENING APPEAR SUFFICIENT ENOUGH BY THE LATE AFTERNOON TO FORCE
THE FIRST SHOWER DEVELOPMENT ALONG THE SUNCOAST ZONES. ANY SHOWERS
THROUGH EARLY EVENING SHOULD BE SCATTERED...SHALLOW AND LIGHT...BUT
DON`T BE SURPRISED TO SEE A FEW RAINDROPS ON THE WINDSHIELD FOR THE
EVENING COMMUTE. THE TRICKY PART OF THE FORECAST COMES IN JUST HOW
QUICKLY THE SOUTHERN WARM-FRONTAL FEATURE MOVES NORTHWARD AND JUST
HOW QUICKLY / AGGRESSIVE THE DEVELOPMENT OF SHOWERS WILL BE ALONG
AND NORTH OF THE BOUNDARY THIS EVENING. AS THE WARM FRONT MOVES
NORTHWARD...THE CHANCES FOR SHOWERS TO THE SOUTH OF THE BOUNDARY
WILL DECLINE...MEANING THE PROPER TIMING OF THE ITS MOVEMENT IS
IMPORTANT. BASED ON AN ENSEMBLE APPROACH TO THE GUIDANCE...THE TAMPA
BAY / I-4 CORRIDOR APPEARS TO BE THE TRANSITION POINT THIS EVENING
AND INTO THE OVERNIGHT BETWEEN WIDELY SCT SHOWERS AND POTENTIALLY
MORE WIDESPREAD ACTIVITY. THE POP GRIDS WILL SHOW THIS PHILOSOPHY
ALONG WITH THE BIAS OF NWP MODELS TO BE TOO SLOW IN THE DEVELOPMENT
AND EXIT OF UPGLIDE PRECIP. CURRENTLY HAVE OVERNIGHT RAIN CHANCES
RISING TO CATEGORICAL ACROSS MUCH OF THE NATURE COAST...LIKELY
THROUGH THE TAMPA BAY REGION...AND THEN CHANCE POPS FURTHER SOUTH
ALONG THE SUNCOAST / INTERIOR SOUTHERN ZONES. SHOWALTER INDICES
NORTH OF THE WARM FRONT ARE ALSO AROUND 0 OR SLIGHT NEGATIVE...AND
HAVE CONTINUED ISOLATED THUNDER MENTION. THE BEST CHANCE OF THUNDER
WILL BE UP OVER THE NATURE COAST WHERE THE DEEPER LIFT WILL EXIST.
AS THE WARM FRONT SLOWLY MOVES NORTH TONIGHT...LOW TEMPS ARE LIKELY
TO OCCUR IN THE LATE EVENING/MIDNIGHT TIME FRAME...AND THEN STEADILY
RISE DURING THE PRE-DAWN HOURS.
SATURDAY...LOW PRESSURE WILL QUICKLY TRANSLATE EASTWARD TO OUR NORTH
DURING SATURDAY MORNING WITH THE WARM FRONT LIFTING NORTH OF OUR
AREA EARLY. SURFACE LOW WILL THEN BEGIN RE-DEVELOPMENT / DEEPENING
OFF THE EASTERN SEABOARD DURING THE AFTERNOON. TRAILING COLD FRONT
WILL QUICKLY MOVE NORTHWEST TO SOUTHEAST ACROSS THE REGION DURING
THE DAY. GFS IS THE FASTEST TO PUSH THE BOUNDARY THROUGH OUR
NORTHERN ZONES...AND THE COLD FRONTAL FORCED BAND OF SHOWERS AND
STORMS IS ESSENTIALLY DONE UP TOWARD LEVY /CITRUS COUNTIES BY
EARLY/MID-MORNING. OTHER GUIDANCE MEMBERS INCLUDING THE
NAM/ECMWF/SREF MEAN ARE A FEW HOURS SLOWER. THE GFS MAY VERY WELL BE
CORRECT IN THE FASTER SOLUTION...BUT WILL SLOW THINGS DOWN BY A
COUPLE HOURS OUT OF RESPECT FOR THE OTHER MEMBERS. EITHER WAY...BEST
SHOWER/STORM CHANCES WILL BE THROUGH 18Z FROM THE TAMPA AREA
/SARASOTA AREA NORTHWARD. GOOD AGREEMENT IN A DECLINE IN
SHOWER/STORM ORGANIZATION ALONG THE FRONT DURING THE AFTERNOON AS
THE BAND MOVES THROUGH THE SOUTHERN ZONES. THIS SCENARIO SEEMS
PLAUSIBLE AS THE SURFACE LOW RACES NORTHEASTWARD AND THE WHOLE
SYSTEM DOWN OUR WAY BEGINS TO BECOME STRETCHED / LESS FOCUSED.
SATURDAY NIGHT/SUNDAY...COLD FRONT AND ANY LINGERING SHOWERS EXIT
INTO SOUTH FLORIDA DURING THE EARLY EVENING AS A COOLER AND DRIER
AIRMASS ARRIVES ON NW FLOW IN THE WAKE OF THE FRONT. TEMPERATURES
WILL BE COOL BY DAWN SUNDAY WITH WIDESPREAD 40S...AND EVEN MID/UPPER
30S FOR CITRUS/LEVY COUNTIES. MAV MOS HAS A FEW 30-32 TEMPS UP OVER
THE FAR NORTH LATE SATURDAY NIGHT...HOWEVER...MOS NUMBERS ARE ALMOST
ALWAYS TOO COLD DURING THE FIRST ADVECTION NIGHT BEHIND A FRONT...
AND FOR NOW FEEL SAFE KEEPING LOW TEMPS ABOVE FREEZING. WIND CHILLS
ARE FORECAST TO BE WELL DOWN INTO THE 30S TO THE NORTH OF THE I-4
CORRIDOR THOUGH BY DAWN. STRONG CONTINENTAL HIGH PRESSURE BUILDS TO
OUR NORTH ON SUNDAY AS HEIGHT RISE OVERHEAD. ALL THIS WILL RESULT IN
A FAIR...BREEZY...AND SEASONABLY COOL DAY UNDER ABUNDANT SUNSHINE.
&&
.LONG TERM (SUNDAY NIGHT THROUGH THURSDAY)...
MODELS ARE IN VERY GOOD AGREEMENT THROUGH WEDNESDAY AND DO NOT
DIVERGE QUITE AS MUCH FOR DAY 7 AS THEY HAD 24 HOURS AGO. THIS
ALLOWED ME TO SLOW THE FRONT DOWN BY 18 TO 24 HOURS WHICH BRINGS IT
THROUGH HERE ON THURSDAY INSTEAD OF WEDNESDAY.
HIGH PRESSURE WILL RESIDE NORTH OF THE REGION SUNDAY NIGHT AND SLIDE
INTO THE ATLANTIC ON MONDAY. THIS WILL TURN OUR WINDS SOUTHEASTERLY
BRINGING WARMER AIR AND HIGHER MOISTURE INTO THE AREA. IN FACT...WE
COULD SEE TEMPERATURES APPROACHING 80 DEGREES ON TUESDAY AND
WEDNESDAY ESPECIALLY SOUTH OF TAMPA BAY. SUNDAY NIGHT SHOULD STILL
BE COOL WITH LOWS IN THE MID 30S NORTH TO MID 40S INTERIOR CENTRAL
AND SOUTH.
ONE POTENTIAL RAIN MAKER WILL BE A WEAKENING FRONTAL BOUNDARY THAT
IS FORECAST TO SETTLE INTO NORTH FLORIDA LATE TUESDAY THEN BECOME
STATIONARY DURING WEDNESDAY. I THINK MOST OF THE AREA WILL GET BY
WITHOUT RAIN ON TUESDAY...BUT SOME SHOWERS COULD AFFECT THE AREA
TUESDAY NIGHT AND ESPECIALLY ON WEDNESDAY. THE BEST CHANCE OF RAIN
ON WEDNESDAY WILL BE NORTH OF TAMPA BAY.
LOW PRESSURE WILL BE DEVELOPING IN THE GULF OF MEXICO WEDNESDAY
NIGHT WHICH WILL ENERGIZE THE STATIONARY FRONTAL BOUNDARY OVER
FLORIDA. THE EXACT PLACEMENT OF THE FRONT IS STILL IN QUESTION...BUT
THINK THERE WILL BE PLENTY OF LIFT FOR SHOWERS AND EVEN A FEW
THUNDERSTORMS IN THE WARM AIR AHEAD OF THE LOW CENTER. AFTER THAT...
THE GFS TAKES LOW PRESSURE QUICKLY ACROSS FLORIDA AND INTO THE
ATLANTIC ON THURSDAY WITH THE FRONT TRAVELING QUICKLY SOUTHEAST
ACROSS THE STATE. THE ECMWF IS SLOWER AND STILL HAS WAVES OF LOW
PRESSURE ALONG THE FRONT ACROSS FLORIDA AND INTO THE GULF ON
THURSDAY. HAVE BASICALLY BLENDED GUIDANCE FOR A COMPROMISE WHICH
WILL CONTINUE OUR RAIN CHANCES THROUGH DAY SEVEN.
&&
.AVIATION...
CLOUDS SHOULD GRADUALLY INCREASE LATER THIS MORNING AND THEN LOWER
THIS AFTERNOON AND TONIGHT. EXPECT VFR CEILINGS AROUND 7000 FEET TO
BECOME MVFR THIS EVENING...THEN IFR AND PERHAPS EVEN LIFR OVERNIGHT.
CONFIDENCE IN MVFR AND IFR CEILINGS IS HIGHER THAN AVERAGE.
&&
.MARINE...
WINDS SHIFT TO THE SOUTHEAST AND SOUTH WITH TIME TODAY AHEAD OF AN
APPROACHING COLD FRONT. CAUTIONARY LEVEL WINDS ARE EXPECTED BY
THIS EVENING OVER THE OFFSHORE WATERS AND THEN EXPANDING OVER ALL
THE FORECAST WATERS AFTER MIDNIGHT. A COLD FRONT AND BAND OF SHOWERS
AND STORMS WILL MOVE NORTHWEST TO SOUTHEAST ACROSS THE EASTERN GULF
OF MEXICO DURING SATURDAY WITH WINDS SHIFTING TO THE NORTHWEST BY
SATURDAY NIGHT. WINDS AND SEAS WILL BUILD TO ADVISORY LEVELS BEHIND
THIS FRONT FOR SATURDAY NIGHT AND SUNDAY WHILE SHIFTING TO THE
NORTHEAST. ELEVATED EASTERLY FLOW TO CAUTIONARY LEVELS IS EXPECTED
TO PERSIST SUNDAY NIGHT INTO MONDAY.
&&
.FIRE WEATHER...
HIGH PRESSURE QUICKLY EXITS TO THE EAST OF THE REGION TODAY AS LOW
PRESSURE ORGANIZES ALONG THE NORTHERN GULF COAST AND APPROACHES FROM
THE WEST. LOW LEVEL MOISTURE WILL BE ON THE INCREASE FROM SOUTH TO
NORTH TODAY. INTERIOR NATURE COAST LOCATIONS MAY BRIEFLY APPROACH 35
PERCENT THIS AFTERNOON...HOWEVER IT NOW APPEARS THAT THE MOISTURE
WILL ARRIVE QUICK ENOUGH TO PREVENT ANY CRITICAL FIRE WEATHER
CONDITIONS. SHOWERS OVERSPREAD THE REGION TONIGHT...ESPECIALLY FROM
TAMPA BAY NORTHWARD. THESE SHOWERS AND EMBEDDED THUNDERSTORMS WILL
THEN SHIFT SOUTH AND EAST DURING SATURDAY AHEAD OF A COLD FRONT.
LINGERING SHOWERS AND THE COLD FRONT WILL EXIT SOUTH OF THE FORECAST
AREA BY SATURDAY EVENING WITH A COOLER AND DRIER AIRMASS ARRIVING
ONCE AGAIN FOR THE SECOND HALF OF THE WEEKEND. RELATIVE HUMIDITY
VALUES ARE CURRENTLY FORECAST TO BRIEFLY REACH CRITICAL LEVELS
SUNDAY AFTERNOON AWAY FROM THE COAST.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 71 64 74 45 / 20 70 70 10
FMY 77 66 79 53 / 20 20 50 10
GIF 71 59 76 46 / 10 60 70 10
SRQ 73 64 74 50 / 20 60 70 10
BKV 69 58 73 42 / 10 80 70 10
SPG 69 64 73 51 / 20 70 70 10
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...FREEZE WARNING UNTIL 8 AM EST THIS MORNING FOR CITRUS-
HERNANDO-LEVY.
GULF WATERS...NONE.
&&
$$
SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA
LONG TERM/AVIATION...JILLSON
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
946 PM EST SAT DEC 29 2012
.SYNOPSIS...
A REINFORCING COLD FRONT WILL MOVE THROUGH THIS EVENING FOLLOWED
BY HIGH PRESSURE THROUGH SUNDAY WHICH WILL THEN SHIFT OFFSHORE BY
MONDAY. ANOTHER FRONTAL SYSTEM WILL DROP INTO THE SOUTHEAST UNITED
STATES TUESDAY AND PERSIST IN THE VICINITY THROUGH THURSDAY NIGHT.
HIGH PRESSURE WILL BUILD BACK IN FOR LATE NEXT WEEK INTO THE
WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
THE FORECAST IS ON TRACK AND THE FORECAST PHILOSOPHY HAS NOT
CHANGED FROM THE EARLIER UPDATE. STRONG COLD AIR ADVECTION IS
ONGOING ACROSS THE REGION AS SHORTWAVE ENERGY PASSING JUST TO THE
NORTH. 925-850MB TRAJECTORIES ARE BACKING MORE SOLIDLY DOWNSLOPE
AND SATELLITE SHOWS CLOUDS RAPIDLY THINNING. EXPECT CLEAR SKIES TO
DOMINATE BY MIDNIGHT. MADE VERY MINOR ADJUSTMENTS TO THE SKY
FORECAST FOR THE NEXT FEW HOURS...BUT NO OTHER CHANGES WERE MADE.
LOWS FROM AROUND 30 WELL INLAND TO THE MID 30S AT THE COAST LOOK
REASONABLE. GUSTY NORTHWEST WINDS WILL MAKE TEMPERATURES FEEL
CONSIDERABLY COOLER WITH WIND CHILLS DROPPING WELL INTO THE 20S
EARLY SUNDAY. WIND GUSTS OF 35-40 MPH CAN BE EXPECTED AND GIVEN
HOW WET THE GROUND IS FROM TWO RECENT MODERATE RAINFALLS...A FEW
DOWNED TREES CAN NOT BE COMPLETELY RULED OUT. LOOKS LIKE WINDS
WILL REMAIN JUST BELOW THE GUST CRITERIA FOR A WIND ADVISORY.
ISSUED A SPECIAL WEATHER STATEMENT TO ADDRESS THE MARGINAL WIND
SITUATION.
LAKE WINDS...A LAKE WIND ADVISORY REMAINS IN FORCE UNTIL 5 AM
SUNDAY FOR LAKE MOULTRIE. WINDS WILL CONTINUE TO PICK UP AS A
STRONGER SURGE OF COLD AIR MOVES ACROSS THE RELATIVELY WARMER LAKE
WATERS. WAVES OF 1-2 FT WILL OCCUR... HIGHEST OVER THE CENTRAL AND
SOUTHEAST PORTIONS OF THE LAKE.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
SUNDAY AND SUNDAY NIGHT...LARGE AND PROMINENT RIDGING ALOFT WILL
BUILD IN FROM THE WEST. AT THE SURFACE...A 1030 MB HIGH WILL SHIFT
EASTWARD INTO THE FORECAST AREA AND LINGER THROUGH THE OVERNIGHT.
DEEP DRY AIR AND LARGE SCALE SUBSIDENCE WILL RESULT IN A DRY AND
CLEAR DAY/NIGHT. COLD AIR ADVECTION WILL CONTINUE THROUGH THE DAY
RESULTING IN COOL HIGH TEMPS. LOW LEVEL THICKNESSES SUPPORT HIGHS
STRUGGLING TO REACH THE LOW 50S. WITH EXCELLENT RADIATIONAL COOLING
CONDITIONS SUNDAY NIGHT...LOWS WILL BOTTOM OUT IN THE UPPER 20S AWAY
FROM THE COAST.
MONDAY THROUGH TUESDAY...THE UPPER RIDGE WILL FLATTEN OUT AND THE
FLOW WILL BECOME MORE ZONAL IN RESPONSE TO A POSITIVELY TILTED
TROUGH PUSHING INTO THE OH VALLEY. AS A RESULT A STRENGTHENING 150
KT UPPER LEVEL JET WILL EXTEND WEST TO EAST ACROSS THE UPPER MIDWEST
AND MID ATLANTIC. THIS WILL HELP DRIVE SURFACE LOW AND COLD FRONT
DEVELOPMENT OVER THE LOWER MS VALLEY BY TUESDAY MORNING. THE FRONT
WILL CONTINUE TO DRIFT EASTWARD WITH PRECIP EXPECTED TO BE OUR THE
DOORSTEP OF THE FORECAST AREA BY TUESDAY AFTERNOON. EXPECT MONDAY TO
BE DRY WITH INCREASING HIGH CLOUDS AND TEMPS RIGHT AROUND NORMAL.
TUESDAY CONTINUES TO FEATURE A DRY MORNING AND POPS INCREASING INTO
THE CHANCE RANGE FOR THE AFTERNOON. AS OF RIGHT NOW...MODELS ARE IN
GOOD AGREEMENT KEEPING THE BULK OF THE PRECIP TO OUR WEST THROUGH
THE DAY.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
TUESDAY NIGHT THROUGH THURSDAY NIGHT LOOK FAIRLY ACTIVE DUE TO A
PLETHORA OF UPPER DISTURBANCES RIPPLING THROUGH THE BROAD EASTERN
UNITED STATES TROUGH. A WEAK FRONT SHOULD REMAIN DRAPED ACROSS THE
FORECAST AREA WITH NUMEROUS SURFACE WAVES RIDING ALONG IT. WE KEPT
CHANCE POPS IN THE FORECAST THROUGH THURSDAY...TAPERING OFF THURSDAY
NIGHT. COOL...DRY HIGH PRESSURE WILL BUILD IN FRIDAY THROUGH
SATURDAY.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
CLOUDS WILL QUICKLY SCOUR OUT THIS EVENING YIELDING CLEAR SKIES.
GUSTY WINDS WILL PERSIST FOR MUCH OF THE HIGHEST WITH WINDS
GUSTING 25-30 KT AT TIMES...MAINLY THROUGH 06Z. ALTHOUGH WINDS
ALOFT WILL BE INCREASING...IT APPEARS SURFACE WINDS WILL REMAIN
ELEVATED ENOUGH TO PRECLUDE LOW-LEVEL WIND SHEAR.
EXTENDED AVIATION OUTLOOK...INCREASING CHANCES FOR SUB-VFR
CONDITIONS LATE TUESDAY AND WEDNESDAY AS A COLD FRONT DROPS SOUTH
INTO THE AREA.
&&
.MARINE...
TONIGHT...WINDS WILL INCREASE EVEN MORE TONIGHT AS A SECONDARY
SURGE OF COLD AIR PUSHES OFF THE COAST AND INTERACTS WITH THE
RELATIVE WARMER ATLANTIC WATERS. SMALL CRAFT ADVISORIES LOOKS WELL
PLACED...BUT OPTED TO UPGRADE TO A GALE WARNING FOR THE GEORGIA
OFFSHORE WATERS WHERE SIGNIFICANTLY WARMER WATERS ASSOCIATED WITH
THE WESTERN WALL OF THE GULF STREAM ARE LOCATED. YESTERDAY/S 1KM
MODIS SEA SURFACE TEMPERATURE DATA INDICATED WATER TEMPERATURES
QUICKLY WARM FROM THE LOWER-MID 50S AROUND 20 NM TO THE LOWER 70S
BEYOND 40 NM. RUC AND H3R BOUNDARY LAYER WIND FORECAST SUGGEST
WINDS COULD EASILY REACH SOLID GALES OF 30-35 KT WITH GUSTS TO 40
KT IN THE OUTER HALF OF THE GEORGIA OFFSHORE ZONES WHERE THE
WARMER WATER TEMPERATURES WILL FAVOR MORE INTENSE VERTICAL MIXING.
OBSERVATIONS FROM 41004 WERE ALREADY GUSTING NEAR 35 KT AT 29/22Z
SO THINK A GALE WARNING IS CERTAINLY WARRANTED ATTM AS WINDS
INCREASE FURTHER. WILL WORD THE HIGHEST WINDS BEYOND 40 NM IN
BOTH THE GALE WARNING ITSELF AND THE COASTAL WATERS FORECAST. SEAS
WILL BUILD AS HIGH 9 FT OFFSHORE...BUT WILL ACTUALLY SUBSIDE A
BIT NEAR THE IMMEDIATE COAST AS THE OFFSHORE FLOW INTENSIFIES.
SUNDAY THROUGH THURSDAY...HIGH PRESSURE WILL BUILD INTO THE AREA ON
SUNDAY. THE MORNING WILL CONTINUE TO SEE ELEVATED SEAS AND STRONG NW
WINDS AS THE WATERS ARE CAUGHT IN THE PINCHED GRADIENT BETWEEN THE
APPROACHING HIGH AND DEPARTING LOW. CONDITIONS SHOULD IMPROVE
QUICKLY INTO THE AFTERNOON...ALLOWING FOR ALL SMALL CRAFT ADVISORIES
TO COME DOWN. THINGS WILL THEN BE QUIET THROUGH MONDAY AS THE HIGH
PASSES OVER THE AREA. INCREASING SOUTHWEST FLOW AHEAD OF THE NEXT
FRONT MAY PUSH WINDS AS HIGH AS 15-20 KT WITH SEAS REACHING 5 FT
OVER THE OUTER PORTIONS BY TUESDAY. A STRONGER SURGE WILL OCCUR LATE
NEXT WEEK WHEN COLD HIGH PRESSURE BUILDS OVER THE WATERS.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...LAKE WIND ADVISORY UNTIL 5 AM EST SUNDAY FOR SCZ045.
MARINE...SMALL CRAFT ADVISORY UNTIL 9 AM EST SUNDAY FOR AMZ330-350-352-
354.
GALE WARNING UNTIL 5 AM EST SUNDAY FOR AMZ374.
&&
$$
ST
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
650 PM EST SAT DEC 29 2012
.SYNOPSIS...
COOL DRY HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE REGION
THROUGH SUNDAY...THEN SHIFT TO OUR EAST LATE MONDAY AHEAD OF A
FRONT THAT WILL SLOWLY MOVE THROUGH TUESDAY AND WEDNESDAY...AND
STALL JUST TO OUR SOUTH THURSDAY.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
13 KM RUC MODEL PICKED UP A WEAK SHORT WAVE THAT CAUSED A FEW
SHOWERS IN THE NORTHEAST PART OF THE FORECAST AREA. SO INCLUDED
A 20-30 PERCENT AREA OF SHOWERS UNTIL CLOSE TO MIDNIGHT.
OTHERWISE...LOW LEVEL CLOUDINESS WILL CONTINUE TO GRADUALLY
DECREASE. PRESSURE GRADIENT OVER THE REGION BETWEEN INTENSIFYING
AREA OF LOW PRESSURE TO OUR NE...MOVING TO THE NE...AND HIGH
PRESSURE CENTERED TO OUR WEST RESULTING IN BREEZY CONDITIONS.
WINDS OVER LAND AREAS TO GRADUALLY DIMINISH TONIGHT...BUT MAY STAY
UP LONGER OVER WARMER LAKE WATERS. WILL MAINTAIN LAKE WIND
ADVISORY THROUGH 1 AM.
MODELS SHOW WINDS DROPPING OFF 1-2 AM. LAMP TEMPERATURES ARE
VERIFYING BETTER THIS EVENING THAN OTHER MOS TEMPERATURES. SO
DECIDED TO USE LAMP HOURLY TEMPS AND MIN TEMP SMART TOOL. THIS
GAVE LOW TEMPERATURES A BIT COLDER MAINLY IN THE UPPER 20S BUT
THERE WERE SOME MID 20S.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
UPPER TROUGHINESS WILL REDEVELOP OVER THE WESTERN CONUS...WITH UPPER
HEIGHT RISES OVER THE SE CONUS. SURFACE HIGH CENTER WILL BUILD INTO
OUR REGION THROUGH LATE SUNDAY AND SUNDAY NIGHT...THEN GRADUALLY
WEAKEN AND SHIFT EAST LATE MON/MON NT. GOOD RADIATIONAL COOLING
CONDITIONS POSSIBLE FOR SUN NT/MON MORNING...ALTHOUGH SOME HIGH
LEVEL CLOUDINESS AHEAD OF THE NEXT SYSTEM COULD MOVE IN LATE.
INCREASING LOWER LEVEL CLOUDINESS POSSIBLE LATE MONDAY NIGHT AHEAD
OF AN APPROACHING FRONT.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
MODELS MAINTAIN GENERAL UPPER TROUGHINESS TO OUR WEST WITH A SW
UPPER FLOW OVER OUR REGION. MODELS GENERALLY AGREE ON A SLOW MOVING
FRONT MOVING THROUGH OUR REGION TUE/WED...AND STALLING JUST TO OUR
SOUTH THURSDAY...AS A PAIR OF SURFACE WAVES MOVE ALONG THE FRONT
THROUGH THE PERIOD. SOME MODEL INCONSISTENCIES NOTED WITH STRENGTH
AND TRACK OF WAVE THURSDAY. MODELS INDICATE THE FRONT WILL PUSH
FARTHER SE FRIDAY...AND SUGGEST ANOTHER SYSTEM MAY AFFECT
OUR REGION BY SATURDAY...BUT CONFIDENCE TOO LOW THIS FAR OUT TO
MENTION PRECIP. GENERALLY ACCEPTED BLEND OF LATEST GUIDANCE AND
ONGOING FORECAST.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
SCATTERED TO BROKEN CLOUDS 3-4 KFT ARE EXPECTED TO CLEAR OFF
03-04Z TIME FRAME. GUSTY WEST WINDS 10-20 KNOTS ARE ALSO EXPECTED
TO DROP TO LESS THAN 10 KNOTS BY 04Z. NO OVERNIGHT FOG WITH DRY
AIR IN PLACE. HIGH PRESSURE WILL PROVIDE CLEAR SKIES FOR SUNDAY.
EXTENDED AVIATION OUTLOOK...NO RESTRICTIONS EXPECTED THROUGH
MONDAY. ANOTHER STORM SYSTEM COULD BRING CIG/VSBY RESTRICTIONS
TUESDAY.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...LAKE WIND ADVISORY UNTIL 1 AM EST SUNDAY FOR SCZ015-016-018-
020>022-025>031-035>038-041.
GA...LAKE WIND ADVISORY UNTIL 1 AM EST SUNDAY FOR GAZ040-063>065-
077.
&&
$$
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
621 PM EST SAT DEC 29 2012
...GALE WARNING ISSUED FOR THE GEORGIA OFFSHORE WATERS...
.SYNOPSIS...
A REINFORCING COLD FRONT WILL MOVE THROUGH THIS EVENING FOLLOWED BY HIGH
PRESSURE THROUGH SUNDAY WHICH WILL THEN SHIFT OFFSHORE BY MONDAY. ANOTHER
FRONTAL SYSTEM WILL DROP INTO THE SOUTHEAST UNITED STATES TUESDAY AND
PERSIST IN THE VICINITY THROUGH THURSDAY NIGHT. HIGH PRESSURE WILL BUILD
BACK IN FOR LATE NEXT WEEK INTO THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
A POTENT SHORTWAVE PIVOTING AROUND THE BASE OF THE LONG-WAVE
TROUGH EXTENDING OUT OF HUDSON BAY CANADA WILL PUSH OFFSHORE THIS
EVENING...USHERING IN ANOTHER SURGE OF COLDER AIR OVER SOUTHEAST
SOUTH CAROLINA AND SOUTHEAST GEORGIA. ALREADY SEEING SIGNIFICANT
PRESSURE RISES OCCUR OVER THE NORTH CAROLINA MOUNTAINS...THE SOUTH
CAROLINA UPSTATE AS WELL AS NORTHERN GEORGIA WHERE A SECONDARY
SURGE OF STRONG COLD AIR ADVECTION IS INITIATING IN THE WAKE OF
THE SHORTWAVE. WINDS WILL SHIFT TO A MORE SOLID DOWNSLOPE
TRAJECTORY OVER THE NEXT FEW HOURS AS THE SHORTWAVE PUSHES
OFFSHORE...WHICH WILL IN TURN EXPEDITE THE CLEARING PROCESS. EARLY
EVENING SATELLITE AND SURFACE OBSERVATIONS ALREADY SHOW A RATHER
LARGE CLEARING AREA STEADILY EXPANDING ACROSS THE UPPER SAVANNAH
RIVER AREA AS WELL AS THE SOUTH CAROLINA MIDLANDS. ADJUSTED THE
SKY FORECAST TO MATCH EXPECTED TRENDS OVER THE NEXT FEW HOURS WITH
CLEAR TO MOSTLY CLEAR SKIES EXPECTED TO PREVAIL BY MIDNIGHT. LOWS
FROM AROUND 30 WELL INLAND TO THE MID 30S AT THE COAST LOOK
REASONABLE. GUSTY NORTHWEST WINDS WILL MAKE TEMPERATURES FEEL
CONSIDERABLY COOLER WITH WIND CHILLS DROPPING WELL INTO THE 20S BY
EARLY SUNDAY.
LAKE WINDS...EXTENDED THE LAKE WIND ADVISORY UNTIL 5 AM SUNDAY.
WINDS ON LAKE MOULTRIE WILL INCREASE TO A SOLID 20 KT LATER THIS
EVENING AS A STRONGER SURGE OF COLD AIR MOVES ACROSS THE
RELATIVELY WARMER LAKE WATERS. WAVES OF 1-2 FT WILL OCCUR...
HIGHEST OVER THE CENTRAL AND SOUTHEAST PORTIONS OF THE LAKE.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
SUNDAY AND SUNDAY NIGHT...LARGE AND PROMINENT RIDGING ALOFT WILL
BUILD IN FROM THE WEST. AT THE SURFACE...A 1030 MB HIGH WILL SHIFT
EASTWARD INTO THE FORECAST AREA AND LINGER THROUGH THE OVERNIGHT.
DEEP DRY AIR AND LARGE SCALE SUBSIDENCE WILL RESULT IN A DRY AND
CLEAR DAY/NIGHT. COLD AIR ADVECTION WILL CONTINUE THROUGH THE DAY
RESULTING IN COOL HIGH TEMPS. LOW LEVEL THICKNESSES SUPPORT HIGHS
STRUGGLING TO REACH THE LOW 50S. WITH EXCELLENT RADIATIONAL COOLING
CONDITIONS SUNDAY NIGHT...LOWS WILL BOTTOM OUT IN THE UPPER 20S AWAY
FROM THE COAST.
MONDAY THROUGH TUESDAY...THE UPPER RIDGE WILL FLATTEN OUT AND THE
FLOW WILL BECOME MORE ZONAL IN RESPONSE TO A POSITIVELY TILTED
TROUGH PUSHING INTO THE OH VALLEY. AS A RESULT A STRENGTHENING 150
KT UPPER LEVEL JET WILL EXTEND WEST TO EAST ACROSS THE UPPER MIDWEST
AND MID ATLANTIC. THIS WILL HELP DRIVE SURFACE LOW AND COLD FRONT
DEVELOPMENT OVER THE LOWER MS VALLEY BY TUESDAY MORNING. THE FRONT
WILL CONTINUE TO DRIFT EASTWARD WITH PRECIP EXPECTED TO BE OUR THE
DOORSTEP OF THE FORECAST AREA BY TUESDAY AFTERNOON. EXPECT MONDAY TO
BE DRY WITH INCREASING HIGH CLOUDS AND TEMPS RIGHT AROUND NORMAL.
TUESDAY CONTINUES TO FEATURE A DRY MORNING AND POPS INCREASING INTO
THE CHANCE RANGE FOR THE AFTERNOON. AS OF RIGHT NOW...MODELS ARE IN
GOOD AGREEMENT KEEPING THE BULK OF THE PRECIP TO OUR WEST THROUGH
THE DAY.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
TUESDAY NIGHT THROUGH THURSDAY NIGHT LOOK FAIRLY ACTIVE DUE TO A
PLETHORA OF UPPER DISTURBANCES RIPPLING THROUGH THE BROAD EASTERN
UNITED STATES TROUGH. A WEAK FRONT SHOULD REMAIN DRAPED ACROSS THE
FORECAST AREA WITH NUMEROUS SURFACE WAVES RIDING ALONG IT. WE KEPT
CHANCE POPS IN THE FORECAST THROUGH THURSDAY...TAPERING OFF THURSDAY
NIGHT. COOL...DRY HIGH PRESSURE WILL BUILD IN FRIDAY THROUGH
SATURDAY.
&&
.AVIATION /23Z SATURDAY THROUGH THURSDAY/...
CLOUDS WILL QUICKLY SCOUR OUT THIS EVENING YIELDING CLEAR SKIES.
GUSTY WINDS WILL PERSIST FOR MUCH OF THE HIGHEST WITH WINDS
GUSTING 25-30 KT AT TIMES...MAINLY THROUGH 06Z. ALTHOUGH WINDS
ALOFT WILL BE INCREASING...IT APPEARS SURFACE WINDS WILL REMAIN
ELEVATED ENOUGH TO PRECLUDE LOW-LEVEL WIND SHEAR.
EXTENDED AVIATION OUTLOOK...INCREASING CHANCES FOR SUB-VFR
CONDITIONS LATE TUESDAY AND WEDNESDAY AS A COLD FRONT DROPS SOUTH
INTO THE AREA.
&&
.MARINE...
TONIGHT...WINDS WILL INCREASE EVEN MORE TONIGHT AS A SECONDARY
SURGE OF COLD AIR PUSHES OFF THE COAST AND INTERACTS WITH THE
RELATIVE WARMER ATLANTIC WATERS. SMALL CRAFT ADVISORIES LOOKS WELL
PLACED...BUT OPTED TO UPGRADE TO A GALE WARNING FOR THE GEORGIA
OFFSHORE WATERS WHERE SIGNIFICANTLY WARMER WATERS ASSOCIATED WITH
THE WESTERN WALL OF THE GULF STREAM ARE LOCATED. YESTERDAY/S 1KM
MODIS SEA SURFACE TEMPERATURE DATA INDICATED WATER TEMPERATURES
QUICKLY WARM FROM THE LOWER-MID 50S AROUND 20 NM TO THE LOWER 70S
BEYOND 40 NM. RUC AND H3R BOUNDARY LAYER WIND FORECAST SUGGEST
WINDS COULD EASILY REACH SOLID GALES OF 30-35 KT WITH GUSTS TO 40
KT IN THE OUTER HALF OF THE GEORGIA OFFSHORE ZONES WHERE THE
WARMER WATER TEMPERATURES WILL FAVOR MORE INTENSE VERTICAL MIXING.
OBSERVATIONS FROM 41004 WERE ALREADY GUSTING NEAR 35 KT AT 29/22Z
SO THINK A GALE WARNING IS CERTAINLY WARRANTED ATTM AS WINDS
INCREASE FURTHER. WILL WORD THE HIGHEST WINDS BEYOND 40 NM IN
BOTH THE GALE WARNING ITSELF AND THE COASTAL WATERS FORECAST. SEAS
WILL BUILD AS HIGH 9 FT OFFSHORE...BUT WILL ACTUALLY SUBSIDE A
BIT NEAR THE IMMEDIATE COAST AS THE OFFSHORE FLOW INTENSIFIES.
SUNDAY THROUGH THURSDAY...HIGH PRESSURE WILL BUILD INTO THE AREA ON
SUNDAY. THE MORNING WILL CONTINUE TO SEE ELEVATED SEAS AND STRONG NW
WINDS AS THE WATERS ARE CAUGHT IN THE PINCHED GRADIENT BETWEEN THE
APPROACHING HIGH AND DEPARTING LOW. CONDITIONS SHOULD IMPROVE
QUICKLY INTO THE AFTERNOON...ALLOWING FOR ALL SMALL CRAFT ADVISORIES
TO COME DOWN. THINGS WILL THEN BE QUIET THROUGH MONDAY AS THE HIGH
PASSES OVER THE AREA. INCREASING SOUTHWEST FLOW AHEAD OF THE NEXT
FRONT MAY PUSH WINDS AS HIGH AS 15-20 KT WITH SEAS REACHING 5 FT
OVER THE OUTER PORTIONS BY TUESDAY. A STRONGER SURGE WILL OCCUR LATE
NEXT WEEK WHEN COLD HIGH PRESSURE BUILDS OVER THE WATERS.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...LAKE WIND ADVISORY UNTIL 5 AM EST SUNDAY FOR SCZ045.
MARINE...SMALL CRAFT ADVISORY UNTIL 9 AM EST SUNDAY FOR AMZ330-350-352-
354.
GALE WARNING UNTIL 5 AM EST SUNDAY FOR AMZ374.
&&
$$
SYNOPSIS...
NEAR TERM...ST
SHORT TERM...BSH
LONG TERM...BSH
AVIATION...ST
MARINE...ST
AREA FORECAST DISCUSSION
NWS LINCOLN IL
902 PM CST SAT DEC 29 2012
.DISCUSSION...
ISSUED 859 PM CST SAT DEC 29 2012
CLEARING EVIDENT ON SAT IMAGERY AND RAPID COOLING ALREADY TAKING
PLACE. DROPPED TEMPS A COUPLE OF DEGREES...AND ADDED WORDING FOR
POTENTIAL PATCHY FOG DEVELOPMENT. HAVE NOT LOST LLVL MOISTURE...
PARTICULARLY IN THE SW...AND IN THE NORTH...THE DEWPOINTS ARE A
LITTLE HIGHER...BUT THE TEMPS ARE DROPPING A LITTLE LOWER...AND
QUICKLY. FOR THE MOST PART THOUGH...FORECAST IS LOOKING GOOD.
CHANGED SOME TRENDS HERE AND THERE...FRESHENED THE HRLY TEMPS AND
THE SKY GRIDS. ZONES OUT MOMENTARILY.
HJS
&&
.AVIATION...
ISSUED 605 PM CST SAT DEC 29 2012
LLVL MOISTURE FINALLY GETTING USHERED OUT OF THE CWA...RATHER
QUICKLY IN THE LAST HOUR. WILL LIKELY HAVE TO AMEND FOR A FASTER
RETURN TO VFR FOR MOST LOCATIONS IN THE NEXT COUPLE OF HOURS
SHOULD THE TREND CONTINUE. WESTERLY WINDS BECOMING MORE
SOUTHWESTERLY IN THE OVERNIGHT AND MORNING HOURS...WITH RETURN OF
CIRRUS MIDMORNING. CIRRUS THE MAIN STORY THROUGH MOST OF TOMORROW
EVENING AND INCREASINGLY SOUTHERLY WINDS AS THE REGION IS BETWEEN
TWO SYSTEMS.
HJS
&&
.PREV DISCUSSION...
ISSUED 220 PM CST SAT DEC 29 2012
THE MAIN CONCERN IS THE STORM SYSTEM FOR MONDAY AND NEW YEARS EVE.
MAJOR DIFFERENCES ARE STILL SHOWING UP BETWEEN THE MODELS ON THIS
ONE. THE NAM IS MUCH STRONGER AND FARTHER NORTH WITH THE BAND OF
HEAVY SNOW...INDICATING 4-7 INCHES OF SNOW ACROSS A LARGE PORTION
OF CENTRAL IL...NORTH OF I-70. PART OF THAT HAS TO DO WITH ITS
CONTINUATION OF STEADY SNOWS IN THE NORTH OVERNIGHT NEW YEARS
EVE...WHERE THE OTHER MODELS DROP PRECIP OFF IN THE EVENING. THAT
ADDITIONAL SNOW SEEMS TO BE LINKED TO THE NAM BEING THE ONLY
MODEL TO TAKE A LOW PRESSURE CENTER ACROSS SOUTHERN ILLINOIS NEW
YEARS EVE NIGHT.
THE CANADIAN GEM HAS A SIMILAR PATH FOR THE SNOW BAND AS THE
NAM...BUT HAS LESS ACCUMULATION. THE ECMWF/GFS/UKMET ARE ALL
MUCH FARTHER SOUTH AND WEAKER WITH THE DYNAMICS/PRECIP IN OUR
AREA. THEY DO INDICATE 2-3 INCHES COULD ACCUMULATE SOUTHEAST OF
I-70...WITH THE NORTHERN EDGE OF 1 INCH NEAR I-72. THAT IS THE
PATH THAT HPC HAS GENERALLY FOLLOWED...AND WE WERE PRIMARILY
INDICATING THAT IN OUR GRIDS. HOWEVER...THE NAM AND RAP WERE THE
ONLY MODELS TO SHOW THE AMOUNT OF SNOW WE PICKED UP IN OUR
SOUTHEAST COUNTIES LAST NIGHT...SO THAT LEAVES SOME UNEASY CONCERN
FOR SUCH A BUSY HOLIDAY NIGHT...IF THAT SNOW BAND DOES SHIFT
NORTH.
WE WILL GENERALLY STAY THE COURSE FOR NOW AND ADJUST AMOUNTS
SLIGHTLY TOWARD THE CURRENT SOUTHWARD CONSENSUS.
SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT
AFTER SOME LINGERING LIGHT SNOW SHOWERS/FLURRIES DEPART TO THE
EAST THIS EVENING...CLEARING SKIES APPEAR POISED TO MOVE INTO
CENTRAL ILLINOIS. NIGHT TIME MOISTURE/CLOUD TRENDS CAN BE A BIT
TRICKY WITH ADVANCING HIGH PRESSURE...SINCE THE SUBSIDENCE
INVERSION CAN SOMETIMES TRAP LOW LEVEL MOISTURE THAT THE WEAKER
LOW LEVEL WINDS ARE UNABLE TO PUSH OUT. THAT CAN LEAD TO BACK-
BUILDING LOW CLOUDS/STRATUS AT NIGHT...AFTER A STEADY CLEARING
PROGRESS IS EVIDENT BEFORE SUNSET. PILOT REPORTS CONFIRM THE THIN
LAYER OF MOISTURE OF THIS CLOUD DECK...SO THE CLEARING MAY
CONTINUE TONIGHT AS ADVERTISED IN THE MODELS. WE DID SLOW DOWN THE
PROGRESSION IN THE SKY GRIDS...BUT DO EVENTUALLY CLEAR THINGS OUT
IN THE EAST TOWARD MORNING.
THE TIMING OF THE CLEARING CAN HAVE A BIG IMPACT ON LOW
TEMPERATURES...BUT WITH CLEARING EXPECTED IN MOST AREAS BY
MORNING...WE SHOULD BE SEE LOWS DROP BELOW NORMAL ACROSS THE
BOARD...WITH SOME SINGLE DIGIT LOWS NW OF THE IL RIVER.
HIGH PRESSURE WILL PROVIDE SUNNY SKIES AND QUIET CONDITIONS ON
SUNDAY...BUT THE QUICKLY APPROACHING LOW PRESSURE SYSTEM WILL
BRING INCREASING CLOUDS SUNDAY NIGHT.
MONDAY MORNING...SNOW SHOULD BEGIN TO ADVANCE ACROSS OUR CENTRAL
COUNTIES FROM SW TO NE. LOOKING AT THE CONSENSUS MODELS
(ECMWF/GFS/UKMET) IT APPEARS THAT THE MAIN PERIOD OF STEADIER
SNOWS WILL BE MONDAY AFTERNOON AND EVENING...WHERE MOST OF THE
ACCUMULATION WILL OCCUR. SNOWFALL TOTALS UNDER THAT SCENARIO WOULD
RANGE FROM LESS THAN A HALF INCH TOWARD PEORIA...WITH THE ONE INCH
LINE AS FAR NORTH AS A LINE FROM RUSHVILLE TO LINCOLN TO
CHAMPAIGN...1-2" FROM THAT LINE SOUTH TO I-70...AND 2-3" SOUTH OF
I-70.
SOME SNOW SHOWERS MAY LINGER IN THE SOUTHEAST AFTER MIDNIGHT NEW
YEARS EVE...BUT PRECIP SHOULD COME TO AN END BY SUNRISE ON
TUESDAY. CLEARING SKIES ARE EVEN FORECAST FOR THE AFTERNOON AS
HIGH PRESSURE BUILDS INTO THE AREA FROM THE WEST. A COLD NIGHT
WILL BE ON TAP TUES NIGHT UNDER CLEAR SKIES AND LIGHT
WINDS...ALONG WITH A FRESH SNOW COVER. LOW TEMPS WOULD LIKELY DROP
BELOW GUIDANCE AND INTO THE SINGLE DIGITS IN MANY AREAS.
LONG TERM...WEDNESDAY THROUGH SATURDAY.
THE EXTENDED PERIOD WILL BE DOMINATED BY COLD AND DRY CONDITIONS
UNDER SURFACE HIGH PRESSURE. THE NORTHERN STEAM STORM TRACK LOOKS
TO REMAIN FARTHER NORTH ACROSS THE GREAT LAKES...AND THE SOUTHERN
STREAM REMAINS SOUTH...PUSHING STORM SYSTEMS ACROSS THE GULF
COAST. WE WILL KEEP HIGHS AND LOWS BELOW NORMAL...WITH THE COLDEST
NIGHT LOOKING LIKE THURSDAY NIGHT.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
609 PM CST SAT DEC 29 2012
.DISCUSSION...
ISSUED 220 PM CST SAT DEC 29 2012
THE MAIN CONCERN IS THE STORM SYSTEM FOR MONDAY AND NEW YEARS EVE.
MAJOR DIFFERENCES ARE STILL SHOWING UP BETWEEN THE MODELS ON THIS
ONE. THE NAM IS MUCH STRONGER AND FARTHER NORTH WITH THE BAND OF
HEAVY SNOW...INDICATING 4-7 INCHES OF SNOW ACROSS A LARGE PORTION
OF CENTRAL IL...NORTH OF I-70. PART OF THAT HAS TO DO WITH ITS
CONTINUATION OF STEADY SNOWS IN THE NORTH OVERNIGHT NEW YEARS
EVE...WHERE THE OTHER MODELS DROP PRECIP OFF IN THE EVENING. THAT
ADDITIONAL SNOW SEEMS TO BE LINKED TO THE NAM BEING THE ONLY
MODEL TO TAKE A LOW PRESSURE CENTER ACROSS SOUTHERN ILLINOIS NEW
YEARS EVE NIGHT.
THE CANADIAN GEM HAS A SIMILAR PATH FOR THE SNOW BAND AS THE
NAM...BUT HAS LESS ACCUMULATION. THE ECMWF/GFS/UKMET ARE ALL
MUCH FARTHER SOUTH AND WEAKER WITH THE DYNAMICS/PRECIP IN OUR
AREA. THEY DO INDICATE 2-3 INCHES COULD ACCUMULATE SOUTHEAST OF
I-70...WITH THE NORTHERN EDGE OF 1 INCH NEAR I-72. THAT IS THE
PATH THAT HPC HAS GENERALLY FOLLOWED...AND WE WERE PRIMARILY
INDICATING THAT IN OUR GRIDS. HOWEVER...THE NAM AND RAP WERE THE
ONLY MODELS TO SHOW THE AMOUNT OF SNOW WE PICKED UP IN OUR
SOUTHEAST COUNTIES LAST NIGHT...SO THAT LEAVES SOME UNEASY CONCERN
FOR SUCH A BUSY HOLIDAY NIGHT...IF THAT SNOW BAND DOES SHIFT
NORTH.
WE WILL GENERALLY STAY THE COURSE FOR NOW AND ADJUST AMOUNTS
SLIGHTLY TOWARD THE CURRENT SOUTHWARD CONSENSUS.
SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT
AFTER SOME LINGERING LIGHT SNOW SHOWERS/FLURRIES DEPART TO THE
EAST THIS EVENING...CLEARING SKIES APPEAR POISED TO MOVE INTO
CENTRAL ILLINOIS. NIGHT TIME MOISTURE/CLOUD TRENDS CAN BE A BIT
TRICKY WITH ADVANCING HIGH PRESSURE...SINCE THE SUBSIDENCE
INVERSION CAN SOMETIMES TRAP LOW LEVEL MOISTURE THAT THE WEAKER
LOW LEVEL WINDS ARE UNABLE TO PUSH OUT. THAT CAN LEAD TO BACK-
BUILDING LOW CLOUDS/STRATUS AT NIGHT...AFTER A STEADY CLEARING
PROGRESS IS EVIDENT BEFORE SUNSET. PILOT REPORTS CONFIRM THE THIN
LAYER OF MOISTURE OF THIS CLOUD DECK...SO THE CLEARING MAY
CONTINUE TONIGHT AS ADVERTISED IN THE MODELS. WE DID SLOW DOWN THE
PROGRESSION IN THE SKY GRIDS...BUT DO EVENTUALLY CLEAR THINGS OUT
IN THE EAST TOWARD MORNING.
THE TIMING OF THE CLEARING CAN HAVE A BIG IMPACT ON LOW
TEMPERATURES...BUT WITH CLEARING EXPECTED IN MOST AREAS BY
MORNING...WE SHOULD BE SEE LOWS DROP BELOW NORMAL ACROSS THE
BOARD...WITH SOME SINGLE DIGIT LOWS NW OF THE IL RIVER.
HIGH PRESSURE WILL PROVIDE SUNNY SKIES AND QUIET CONDITIONS ON
SUNDAY...BUT THE QUICKLY APPROACHING LOW PRESSURE SYSTEM WILL
BRING INCREASING CLOUDS SUNDAY NIGHT.
MONDAY MORNING...SNOW SHOULD BEGIN TO ADVANCE ACROSS OUR CENTRAL
COUNTIES FROM SW TO NE. LOOKING AT THE CONSENSUS MODELS
(ECMWF/GFS/UKMET) IT APPEARS THAT THE MAIN PERIOD OF STEADIER
SNOWS WILL BE MONDAY AFTERNOON AND EVENING...WHERE MOST OF THE
ACCUMULATION WILL OCCUR. SNOWFALL TOTALS UNDER THAT SCENARIO WOULD
RANGE FROM LESS THAN A HALF INCH TOWARD PEORIA...WITH THE ONE INCH
LINE AS FAR NORTH AS A LINE FROM RUSHVILLE TO LINCOLN TO
CHAMPAIGN...1-2" FROM THAT LINE SOUTH TO I-70...AND 2-3" SOUTH OF
I-70.
SOME SNOW SHOWERS MAY LINGER IN THE SOUTHEAST AFTER MIDNIGHT NEW
YEARS EVE...BUT PRECIP SHOULD COME TO AN END BY SUNRISE ON
TUESDAY. CLEARING SKIES ARE EVEN FORECAST FOR THE AFTERNOON AS
HIGH PRESSURE BUILDS INTO THE AREA FROM THE WEST. A COLD NIGHT
WILL BE ON TAP TUES NIGHT UNDER CLEAR SKIES AND LIGHT
WINDS...ALONG WITH A FRESH SNOW COVER. LOW TEMPS WOULD LIKELY DROP
BELOW GUIDANCE AND INTO THE SINGLE DIGITS IN MANY AREAS.
LONG TERM...WEDNESDAY THROUGH SATURDAY.
THE EXTENDED PERIOD WILL BE DOMINATED BY COLD AND DRY CONDITIONS
UNDER SURFACE HIGH PRESSURE. THE NORTHERN STEAM STORM TRACK LOOKS
TO REMAIN FARTHER NORTH ACROSS THE GREAT LAKES...AND THE SOUTHERN
STREAM REMAINS SOUTH...PUSHING STORM SYSTEMS ACROSS THE GULF
COAST. WE WILL KEEP HIGHS AND LOWS BELOW NORMAL...WITH THE COLDEST
NIGHT LOOKING LIKE THURSDAY NIGHT.
&&
.AVIATION...
ISSUED 605 PM CST SAT DEC 29 2012
LLVL MOISTURE FINALLY GETTING USHERED OUT OF THE CWA...RATHER
QUICKLY IN THE LAST HOUR. WILL LIKELY HAVE TO AMEND FOR A FASTER
RETURN TO VFR FOR MOST LOCATIONS IN THE NEXT COUPLE OF HOURS
SHOULD THE TREND CONTINUE. WESTERLY WINDS BECOMING MORE
SOUTHWESTERLY IN THE OVERNIGHT AND MORNING HOURS...WITH RETURN OF
CIRRUS MIDMORNING. CIRRUS THE MAIN STORY THROUGH MOST OF TOMORROW
EVENING AND INCREASINGLY SOUTHERLY WINDS AS THE REGION IS BETWEEN
TWO SYSTEMS.
HJS
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1141 AM EST FRI DEC 28 2012
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW
&&
.SYNOPSIS...
ISSUED AT 333 AM EST FRI DEC 28 2012
HIGH PRESSURE OVER CENTRAL INDIANA WILL BE FOLLOWED BY A WEAK COLD
FRONT THIS AFTERNOON INTO TONIGHT. HIGH PRESSURE IS FORECAST TO
RETURN FOR THE WEEKEND. MONDAY ANOTHER COLD FRONT IS EXPECTED TO
CROSS OUR STATE. AFTER THAT...HIGH PRESSURE WILL TAKE CHARGE AGAIN
FOR SEVERAL DAYS. MUCH COLDER AIR WILL ARRIVE OVER THE REGION LATE
NEXT WEEK...WITH LOW TEMPERATURES DROPPING INTO THE SINGLE DIGITS.
&&
.NEAR TERM /TODAY/...
ISSUED AT 1000 AM EST FRI DEC 28 2012
NEITHER RUC NOR HRR BRING IN ANY QPF TIL AFTER 00Z...WHICH LINES
UP WELL WITH MAV AND ECM POPS. WILL DROP POPS BELOW 15 MOST AREAS.
PLAN TO RETAIN THEM SOUTHWEST BUT MAKE THEM LOWER AND INDICATE ANY
PCPN COMING IN QUITE LATE.
TEMPERATURES LOOKING GOOD FOR THE MOST PART. BUT DID MAKE MINOR
TWEAKS BASED ON LATEST OBS.
&&
.SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...
ISSUED AT 333 AM EST FRI DEC 28 2012
FORECAST FOCUS WAS ON SNOW FORECAST FOR TONIGHT PERIOD.
LATEST MODEL RUNS SHOW BETTER MOISTURE AND LIFT ACROSS THE OHIO
VALLEY FROM 00-12Z. THE GFS AND GEM ESPECIALLY ARE DEPICTING MUCH
HIGHER MOISTURE AMOUNTS OF OVER FOUR TENTHS OF AN INCH ACROSS THE
FAR SE COUNTIES...WHILE THE NAM STICKS TO AROUND A TENTH. THE LATEST
EURO APPEARS TO TAKE A BLEND OF THE THE DIFFERING
SOLUTIONS...PLACING AROUND TWO TO THREE TENTHS OF AN INCH OF QPF
ACROSS THE SE COUNTIES...WHICH SEEMS MORE REASONABLE AND IN LINE
WITH HPC GUIDANCE. TRENDED FORECAST WITH HIGHER POPS...ESPECIALLY
ACROSS THE SOUTH AND EAST WHERE THIS FEATURE WILL MOVE CLOSEST TO.
TOTAL SNOWFALL AMOUNTS WILL RANGE FROM 0.5-1.0 INCHES NORTHWEST...TO
2 TO 3 INCHES SOUTHEAST. ADVISORY CRITERIA IS 4 INCHES...SO OPTED
NOT TO ISSUE ONE AT THIS TIME AND PLAN ON SENDING OUT AN SPS. PRECIP
TYPE DOES NOT LOOK TO BE AN ISSUE FOR TONIGHT AND SHOULD BE ALL
SNOW.
SYSTEM STILL LOOKS FAIRLY PROGRESSIVE AND SHOULD BE MOVING AWAY FROM
THE FORECAST AREA...HOWEVER A FEW SHOW SHOWERS AND/OR FLURRIES MAY
LINGER ON THE BACK SIDE OF LOW. WIDESPREAD CLEARING DOES NOT BEGIN
UNTIL SATURDAY NIGHT. HIGH PRESSURE AND DRIER WEATHER WILL BE THE
RULE FOR THE REST OF THE PERIOD.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
ISSUED AT 333 AM EST FRI DEC 28 2012
FORECAST FOCUS IS ON CHANCES FOR SNOW MONDAY THROUGH TUESDAY. MODELS
AND ENSEMBLES ARE SHOWING A DECENT AMOUNT OF VARIABILITY BY MONDAY
AND SAW NO REASON TO CHANGE FROM ALLBLEND. A CLIPPER TYPE SYSTEM
WILL MOVE ACROSS ONTARIO INTO QUEBEC AND POSSIBLY BRING A COLD FRONT
THROUGH ON MONDAY WHICH COULD PROMPT CHANCES FOR SNOW. MONDAY NIGHT
A LOW FORMS IN THE SOUTHERN PLAINS AND TRACKS NORTHEAST INTO
TUESDAY. RIGHT NOW OPERATIONAL GFS AND ECMWF FAVOR A TRACK ACROSS
WESTERN TENNESSEE AND THROUGH EASTERN KENTUCKY WHICH WOULD FAVOR
HIGH POPS FOR THE SOUTH AND CENTRAL COUNTIES...BUT THE MAJORITY OF
THE ENSEMBLE MEMBERS TRACK THIS LOW QUITE A BIT FURTHER SOUTH WHICH
WOULD BE MUCH LESS FAVORABLE. THUS THE ALLBLEND CHANCE POPS WITH THE
HIGHEST NUMBERS IN THE SOUTH LOOK GOOD FOR NOW AND A COMPROMISE.
THERMAL PROFILES IN THE SOUTH INDICATE POTENTIAL FOR SOME MIXED
PRECIP AND WILL KEEP THE RAIN SNOW MIX IN THE SOUTH MONDAY AFTERNOON
FROM PREVIOUS FORECAST. WILL HAVE TO CONTINUE TO MONITOR PRECIP TYPE
WITH UPCOMING FORECASTS FOR THIS TIME.
BY TUESDAY NIGHT HIGH PRESSURE BUILDS IN AND SHUTS DOWN SNOW CHANCES
FOR THE REST OF THE EXTENDED. WITH SNOW COVER CONTINUING AND COLD
AIR INTRUSIONS MAKING THEIR WAY FURTHER SOUTH WITH THE FRONTAL
PASSAGE SHOULD SEE BELOW NORMAL TEMPERATURES AFTER MONDAY.
&&
.AVIATION /DISCUSSION FOR THE 281800Z TAF ISSUANCE/...
ISSUED AT 1141 AM EST FRI DEC 28 2012
GENERALLY MVFR CONDITIONS GIVING WAY TO IFR AFTER 00Z.
CEILINGS WILL GENERALLY HANG AROUND BKN015-BKN025 THROUGH
00Z...BUT THERE IS A CHANCE SOME OF THE BREAKS IN THE LOWER CLOUDS
ACROSS SOUTHERN ILLINOIS COULD WORK INTO THE SITES. HOWEVER STUCK
WITH THE PESSIMISTIC FORECAST BASED ON AN INVERSION ALOFT AND
PERSISTANCE.
SNOW WILL OVERSPREAD THE AREA AFTER 00Z FROM SOUTHWEST TO
NORTHEAST RESULTING IN IFR CEILINGS AND VISIBILITIES. LIFR
CONDITIONS ARE POSSIBLE IN SOME HEAVIER BANDS OF SNOW. SNOW WILL
EXIT THE AREA BEF0RE 12Z BUT IFR CEILINGS SHOULD PERSIST THROUGH
AT LEAST 18Z SATURDAY.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...SMF
NEAR TERM...JK
SHORT TERM...SMF
LONG TERM....CP
AVIATION...50
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1000 AM EST FRI DEC 28 2012
.UPDATE...
THE NEAR TERM SECTION HAS BEEN UPDATED BELOW
&&
.SYNOPSIS...
ISSUED AT 333 AM EST FRI DEC 28 2012
HIGH PRESSURE OVER CENTRAL INDIANA WILL BE FOLLOWED BY A WEAK COLD
FRONT THIS AFTERNOON INTO TONIGHT. HIGH PRESSURE IS FORECAST TO
RETURN FOR THE WEEKEND. MONDAY ANOTHER COLD FRONT IS EXPECTED TO
CROSS OUR STATE. AFTER THAT...HIGH PRESSURE WILL TAKE CHARGE AGAIN
FOR SEVERAL DAYS. MUCH COLDER AIR WILL ARRIVE OVER THE REGION LATE
NEXT WEEK...WITH LOW TEMPERATURES DROPPING INTO THE SINGLE DIGITS.
&&
.NEAR TERM /TODAY/...
ISSUED AT 1000 AM EST FRI DEC 28 2012
NEITHER RUC NOR HRR BRING IN ANY QPF TIL AFTER 00Z...WHICH LINES
UP WELL WITH MAV AND ECM POPS. WILL DROP POPS BELOW 15 MOST AREAS.
PLAN TO RETAIN THEM SOUTHWEST BUT MAKE THEM LOWER AND INDICATE ANY
PCPN COMING IN QUITE LATE.
TEMPERATURES LOOKING GOOD FOR THE MOST PART. BUT DID MAKE MINOR
TWEAKS BASED ON LATEST OBS.
&&
.SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...
ISSUED AT 333 AM EST FRI DEC 28 2012
FORECAST FOCUS WAS ON SNOW FORECAST FOR TONIGHT PERIOD.
LATEST MODEL RUNS SHOW BETTER MOISTURE AND LIFT ACROSS THE OHIO
VALLEY FROM 00-12Z. THE GFS AND GEM ESPECIALLY ARE DEPICTING MUCH
HIGHER MOISTURE AMOUNTS OF OVER FOUR TENTHS OF AN INCH ACROSS THE
FAR SE COUNTIES...WHILE THE NAM STICKS TO AROUND A TENTH. THE LATEST
EURO APPEARS TO TAKE A BLEND OF THE THE DIFFERING
SOLUTIONS...PLACING AROUND TWO TO THREE TENTHS OF AN INCH OF QPF
ACROSS THE SE COUNTIES...WHICH SEEMS MORE REASONABLE AND IN LINE
WITH HPC GUIDANCE. TRENDED FORECAST WITH HIGHER POPS...ESPECIALLY
ACROSS THE SOUTH AND EAST WHERE THIS FEATURE WILL MOVE CLOSEST TO.
TOTAL SNOWFALL AMOUNTS WILL RANGE FROM 0.5-1.0 INCHES NORTHWEST...TO
2 TO 3 INCHES SOUTHEAST. ADVISORY CRITERIA IS 4 INCHES...SO OPTED
NOT TO ISSUE ONE AT THIS TIME AND PLAN ON SENDING OUT AN SPS. PRECIP
TYPE DOES NOT LOOK TO BE AN ISSUE FOR TONIGHT AND SHOULD BE ALL
SNOW.
SYSTEM STILL LOOKS FAIRLY PROGRESSIVE AND SHOULD BE MOVING AWAY FROM
THE FORECAST AREA...HOWEVER A FEW SHOW SHOWERS AND/OR FLURRIES MAY
LINGER ON THE BACK SIDE OF LOW. WIDESPREAD CLEARING DOES NOT BEGIN
UNTIL SATURDAY NIGHT. HIGH PRESSURE AND DRIER WEATHER WILL BE THE
RULE FOR THE REST OF THE PERIOD.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
ISSUED AT 333 AM EST FRI DEC 28 2012
FORECAST FOCUS IS ON CHANCES FOR SNOW MONDAY THROUGH TUESDAY. MODELS
AND ENSEMBLES ARE SHOWING A DECENT AMOUNT OF VARIABILITY BY MONDAY
AND SAW NO REASON TO CHANGE FROM ALLBLEND. A CLIPPER TYPE SYSTEM
WILL MOVE ACROSS ONTARIO INTO QUEBEC AND POSSIBLY BRING A COLD FRONT
THROUGH ON MONDAY WHICH COULD PROMPT CHANCES FOR SNOW. MONDAY NIGHT
A LOW FORMS IN THE SOUTHERN PLAINS AND TRACKS NORTHEAST INTO
TUESDAY. RIGHT NOW OPERATIONAL GFS AND ECMWF FAVOR A TRACK ACROSS
WESTERN TENNESSEE AND THROUGH EASTERN KENTUCKY WHICH WOULD FAVOR
HIGH POPS FOR THE SOUTH AND CENTRAL COUNTIES...BUT THE MAJORITY OF
THE ENSEMBLE MEMBERS TRACK THIS LOW QUITE A BIT FURTHER SOUTH WHICH
WOULD BE MUCH LESS FAVORABLE. THUS THE ALLBLEND CHANCE POPS WITH THE
HIGHEST NUMBERS IN THE SOUTH LOOK GOOD FOR NOW AND A COMPROMISE.
THERMAL PROFILES IN THE SOUTH INDICATE POTENTIAL FOR SOME MIXED
PRECIP AND WILL KEEP THE RAIN SNOW MIX IN THE SOUTH MONDAY AFTERNOON
FROM PREVIOUS FORECAST. WILL HAVE TO CONTINUE TO MONITOR PRECIP TYPE
WITH UPCOMING FORECASTS FOR THIS TIME.
BY TUESDAY NIGHT HIGH PRESSURE BUILDS IN AND SHUTS DOWN SNOW CHANCES
FOR THE REST OF THE EXTENDED. WITH SNOW COVER CONTINUING AND COLD
AIR INTRUSIONS MAKING THEIR WAY FURTHER SOUTH WITH THE FRONTAL
PASSAGE SHOULD SEE BELOW NORMAL TEMPERATURES AFTER MONDAY.
&&
.AVIATION /DISCUSSION FOR 281500 TAF UPDATE/...
ISSUED AT 925 AM EST FRI DEC 28 2012
MVFR CONDITIONS WILL CONTINUE. DID LOWER CEILINGS TO BELOW 2000FT
BASED ON CURRENT CONDITIONS AND UPSTREAM OBSERVATIONS. COULD STILL
RISE ABOVE 2000FT FOR A TIME THIS AFTERNOON. SNOW STILL LOOKS TO
HOLD OFF TILL AFTER 00Z.
PREVIOUS DISCUSSION FOLLOWS...
MVFR CEILINGS WILL REMAIN THROUGHOUT THE DAY TODAY BEFORE DROPPING
TO IFR TONIGHT WITH THE ARRIVAL OF SOME SNOW. COULD SEE SOME
FLURRIES BEFOREHAND BUT EXPECT SNOW OF ANY IMPACT TO THE SITES
WON/T COME IN UNTIL AFTER 0Z. KLAF COULD BE NORTH ENOUGH TO AVOID
SNOW ALTOGETHER BUT CONTINUED WITH A FLURRY MENTION THERE. SNOW
SHOULD MOVE OUT OF THE AREA BY SATURDAY MORNING...AND AFTER THE
SNOW GUIDANCE SHOWS MVFR TO IFR VISIBILITIES AND CEILINGS
REMAINING AND AGREE WITH THIS BASED ON LIGHTER WINDS AND A LOW
PRESSURE TO THE SOUTH.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...SMF
NEAR TERM...JK
SHORT TERM...SMF
LONG TERM....CP
AVIATION...CP/50
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
916 PM CST SAT DEC 29 2012
.UPDATE...
LOW CLOUDS EXITING FAR EAST SECTIONS ATTIM... WITH ATTENTION NOW
SHIFTING TO COUPLE OF AREAS OF LOW CLOUDS TO OUR N/NW. THE
LOW CLOUDS OVER MN INTO WI ARE ON BACK SIDE OF DEPARTING TROUGH.
MEANWHILE... SMALL AREA OF LOW CLOUDS OVER NW INTO NCTRL IA APPEARS
ATTENDANT TO ZONE OF LOW LEVEL WARM ADVECTION. MOST MODELS NOT
HANDLING THESE CLOUDS WELL EXCEPT RAP MODEL BUT IT IS OVERDONE WITH
EXTENT. LAST 60 MINS OF 11-3.9 MICRON SATELLITE LOOP SHOW LOW CLOUDS
MOVING NEARLY DUE EAST TO EVEN SLIGHTLY SOUTH OF EAST. THIS IS IN
LINE WITH LOW LEVEL WIND FIELDS WHICH ARE ROUGHLY FROM WNW OR ROUGHLY
280-290 DEGREES. ON THIS TRAJECTORY WOULD EXPECT SOME OF THESE LOW
CLOUDS TO MAKE IT INTO AT LEAST THE FAR NORTHERN CWA LATE EVE AND
OVRNGT. AS RESULT... WILL BE SENDING UPDATE TO INCREASE CLOUD COVER
MAINLY ALONG AND NORTH OF HWY 20. CANT RULE OUT DEVELOPMENT OR
PROPAGATION TO BRING LOW CLOUD DECK FARTHER SOUTH TOWARDS KCID TO
KSQI LINE... BUT WILL HOLD ON INCREASING CLOUDS THAT FAR SOUTH FOR
NOW AND CONTINUE TO MONITOR TRENDS. WITH THE LOW CLOUDS ALSO EXPECTING
SOME FLURRIES AS SEEN IN OBS. AS CLOUD TRENDS GO... SO GO THE TEMPS.
FOR NOW MADE FEW CHGS TO MINS NORTH WITH PROGRESSIVE NATURE OF THE
CLOUDS. ELSEWHERE... HAVE TRIMMED LOWS BY COUPLE DEGS IN MANY AREAS
WITH GENERALLY CLEAR SKIES.
&&
.PREV DISCUSSION... /ISSUED 600 PM CST SAT DEC 29 2012/
AVIATION...
BACK EDGE OF STRATUS WITH LOW MVFR CIGS ARE CLEARING KDBQ AND KMLI
OVER THE NEXT 1-2 HRS. SURFACE RIDGE AXIS TO OUR WEST WILL PASS
THROUGH THE TERMINALS BY LATE TONIGHT. NW WINDS 5-10 KTS WILL BECOME
LIGHT S/SW AT OR BELOW 5 KTS. RECENT OBS AND SATELLITE DATA CONTINUE
TO SHOW AREAS OF LOW CLOUDS WITH IFR TO LIFR CIGS OVER NORTHWEST IA
IN ZONE OF STRONGEST LOW LEVEL WARM ADVECTION. SOME OF THE LATEST
SHORT RANGE MODEL GUIDANCE CONTINUES TO HINT AT THESE CLOUDS MOVING
AND/OR DEVELOPING E/SE ACROSS THE TERMINALS OVERNIGHT. HAVE
CONTINUED MENTION OF FOG WITH MVFR VSBYS AT TERMINALS DUE TO LIGHT
WINDS... AND HAVE HINTED AT LOW CLOUD POTENTIAL AFT 08Z THROUGH 15Z
WITH SCT IFR CLOUDS AND CONTINUE TO MONITOR TRENDS FOR INCLUSION OF
IFR TO LIFR CONDITIONS AT TERMINALS. ANY LOW CLOUDS AND FOG LIKELY TO
DISSIPATE BY LATE MORNING INTO EARLY AFTERNOON SUNDAY WITH
SOUTHERLY WINDS INCREASING TO AROUND 10 KTS.
PREV DISCUSSION... /ISSUED 307 PM CST SAT DEC 29 2012/
SYNOPSIS...
THE MORNING UA ANALYSIS SHOWED AN UPPER TROF OVER THE CENTRAL U.S.
THE MAIN TROF AXIS EXTENDED FROM LAKE MICHIGAN THROUGH THE LOWER
OHIO VALLEY WITH A SECONDARY SHORT WAVE OVER WESTERN IOWA. AT THE
SURFACE THE REGION WAS UNDER CYCLONIC FLOW ASSOCIATED WITH LOW
PRESSURE OFF THE MID ATLANTIC COAST. WIDESPREAD LOW CLOUDS OVER THE
AREA THIS MORNING WERE ACCOMPANIED BY SOME LIGHT SNOW. THE CLOUDS
HAVE BEEN STEADILY CLEARING FROM WEST TO EAST THROUGH EARLY THIS
AFTERNOON.
SHORT TERM...TONIGHT AND SUNDAY...
EXTRAPOLATION OF THE CLEARING LINE HAS THE BACK EDGE OF THE LOW
CLOUDS EAST OF THE CWFA BY 03Z. THIS LOOKS REASONABLE...EXCEPT FOR
NORTHWEST ILLINOIS WHERE MODEL PROGS HOLD HIGHER VALUES OF LOW LEVEL
RH THROUGH MIDNIGHT AS THE LOW LEVEL RIDGE BUILDS INTO THAT AREA
FIRST. HAVE SET THE GRIDS UP FOR A FASTER CLEARING TREND OVER THE
SOUTHWEST HALF OF THE AREA THIS EVENING AND A LITTLE SLOWER TREND IN
THE NORTHEAST. THERE IS ALSO SOME CONCERN FOR STRATUS AND FOG
DEVELOPING JUST EAST OF THE RIDGE AXIS LATE TONIGHT...SIMILAR TO
WHAT HAPPENED IN EASTERN SOUTH DAKOTA THIS MORNING. THE RAP AND NAM
5KM RH PROGS WERE HINTING AT THIS OCCURRING OVER EASTERN IA AFTER
MIDNIGHT. WHILE THIS CANNOT BE RULED OUT...THERE IS NOT ENOUGH
CONFIDENCE IN ITS OCCURRENCE TO INCLUDE IN THE FORECAST JUST YET.
CLEARING SKIES AND LIGHT WINDS TONIGHT SHOULD ALLOW FOR GOOD
RADIATIONAL COOLING WITH LOWS JUST BELOW ZERO NORTHWEST TO AROUND
10 IN THE SOUTHEAST. THE SURFACE RIDGE AXIS WILL BE EAST OF THE
AREA BY 12Z SUNDAY WITH SOUTH WINDS INCREASING DURING THE DAY AS THE
RIDGE CONTINUES TO MOVE EAST AND A COLD FRONT MOVES INTO NORTHWEST
IOWA. HIGH CLOUDS WILL ALSO BE ON THE INCREASE. TEMPERATURES WILL
BE A CHALLENGE TOMORROW WITH MODELS SHOWING A SHALLOW BUT STRONG
INVERSION OVER THE AREA. HIGHS IN THE MID 20S NORTH TO LOW 30S SOUTH
WERE BASED ON THE SHALLOW MIXING. IF WINDS ARE STRONGER THAN
FORECAST THEN...MIXING WILL BE DEEPER AND THE FORECAST HIGHS WILL BE
ON THE COLD SIDE. DLF
LONG TERM...MONDAY THROUGH SATURDAY
TWO MAIN CONCERNS IN THIS TIME FRAME ARE THE WEAK CYCLOGENESIS
EVENT WHICH COULD BRING PRECIP TO THE SOUTH LATE MONDAY AND EARLY
TUESDAY...AND THE MUDDLE AMONGST THE MODELS WITH THE UPPER AIR
PATTERN AND SUBSEQUENT DETAILS MIDWEEK.
REGARDING THE MONDAY EVENT...THE NAM IS MORE VIGOROUS AND FURTHER
NORTH WITH DEVELOPING THE LOW THAN THE GFS AND ECMWF...WHICH ARE
WEAKER AND FURTHER SOUTH. HAVE SHADED POPS TO FAVOR THE GFS/ECMWF
SOLUTIONS AND KEPT QPF/SNOW ON THE LIGHT SIDE.
AT MID WEEK...THE EXTENDED MODELS ARE INCONSISTENT AMONG
THEMSELVES AND FROM RUN TO RUN IN HANDLING THE COMPLEX SPLIT FLOW
PATTERN WHICH INCLUDES A SOUTHWEST U.S. CUTOFF AND AN ACTIVE
NORTHERN STREAM. THE 12Z ECMWF MOVES A CLIPPER SYSTEM TO OUR
NORTHEAST WEDNESDAY-THURSDAY...WHICH IS FURTHER NORTH AND EAST AT
THAN AT 00Z WHEN IT WAS PROGGED OVER OUR AREA. MEANWHILE...THE
12Z GFS PROGS THIS CLIPPER SYSTEM FASTER AND EVEN FURTHER
NORTHEAST...SO IT APPEARS THIS WOULD BE A NONEVENT FOR US.
THE GFS DOES HOLD MORE ENERGY BACK OVER THE NORTHERN ROCKIES WHICH
EVENTUALLY CUTS OFF AND DRIFTS ACROSS THE CENTRAL U.S. THROUGH
THE WEEKEND. HOWEVER...THIS GFS RUN IS AN OUTLIER RELATIVE TO THE 00Z
ENSEMBLE MEAN.
THUS FAITH IN ANY OF THESE SOLUTIONS IS LOW. HOWEVER...THE COMMON
THEME IS THAT TROUGHINESS DEVELOPS AND PROGRESSES THROUGH THE
CENTRAL U.S. LATE NEXT WEEK. THERE APPEARS TO BE NO SIGNIFICANT
PRECIP EVENT IN THIS TIME FRAME...AND INDICATIONS ARE THAT
REENFORCING COLD AIR MIGHT GIVE US OUR COLDEST TEMPS SO FAR THIS
SEASON SOMETIME LATE NEXT WEEK INTO THE WEEKEND. WOLF
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
600 PM CST SAT DEC 29 2012
.AVIATION...
BACK EDGE OF STRATUS WITH LOW MVFR CIGS ARE CLEARING KDBQ AND KMLI
OVER THE NEXT 1-2 HRS. SURFACE RIDGE AXIS TO OUR WEST WILL PASS
THROUGH THE TERMINALS BY LATE TONIGHT. NW WINDS 5-10 KTS WILL BECOME
LIGHT S/SW AT OR BELOW 5 KTS. RECENT OBS AND SATELLITE DATA CONTINUE
TO SHOW AREAS OF LOW CLOUDS WITH IFR TO LIFR CIGS OVER NORTHWEST IA
IN ZONE OF STRONGEST LOW LEVEL WARM ADVECTION. SOME OF THE LATEST
SHORT RANGE MODEL GUIDANCE CONTINUES TO HINT AT THESE CLOUDS MOVING
AND/OR DEVELOPING E/SE ACROSS THE TERMINALS OVERNIGHT. HAVE
CONTINUED MENTION OF FOG WITH MVFR VSBYS AT TERMINALS DUE TO LIGHT
WINDS... AND HAVE HINTED AT LOW CLOUD POTENTIAL AFT 08Z THROUGH 15Z
WITH SCT IFR CLOUDS AND CONTINUE TO MONITOR TRENDS FOR INCLUSION OF
IFR TO LIFR CONDITIONS AT TERMINALS. ANY LOW CLOUDS AND FOG LIKELY TO
DISSIPATE BY LATE MORNING INTO EARLY AFTERNOON SUNDAY WITH
SOUTHERLY WINDS INCREASING TO AROUND 10 KTS.
&&
.PREV DISCUSSION... /ISSUED 307 PM CST SAT DEC 29 2012/
SYNOPSIS...
THE MORNING UA ANALYSIS SHOWED AN UPPER TROF OVER THE CENTRAL U.S.
THE MAIN TROF AXIS EXTENDED FROM LAKE MICHIGAN THROUGH THE LOWER
OHIO VALLEY WITH A SECONDARY SHORT WAVE OVER WESTERN IOWA. AT THE
SURFACE THE REGION WAS UNDER CYCLONIC FLOW ASSOCIATED WITH LOW
PRESSURE OFF THE MID ATLANTIC COAST. WIDESPREAD LOW CLOUDS OVER THE
AREA THIS MORNING WERE ACCOMPANIED BY SOME LIGHT SNOW. THE CLOUDS
HAVE BEEN STEADILY CLEARING FROM WEST TO EAST THROUGH EARLY THIS
AFTERNOON.
SHORT TERM...TONIGHT AND SUNDAY...
EXTRAPOLATION OF THE CLEARING LINE HAS THE BACK EDGE OF THE LOW
CLOUDS EAST OF THE CWFA BY 03Z. THIS LOOKS REASONABLE...EXCEPT FOR
NORTHWEST ILLINOIS WHERE MODEL PROGS HOLD HIGHER VALUES OF LOW LEVEL
RH THROUGH MIDNIGHT AS THE LOW LEVEL RIDGE BUILDS INTO THAT AREA
FIRST. HAVE SET THE GRIDS UP FOR A FASTER CLEARING TREND OVER THE
SOUTHWEST HALF OF THE AREA THIS EVENING AND A LITTLE SLOWER TREND IN
THE NORTHEAST. THERE IS ALSO SOME CONCERN FOR STRATUS AND FOG
DEVELOPING JUST EAST OF THE RIDGE AXIS LATE TONIGHT...SIMILAR TO
WHAT HAPPENED IN EASTERN SOUTH DAKOTA THIS MORNING. THE RAP AND NAM
5KM RH PROGS WERE HINTING AT THIS OCCURRING OVER EASTERN IA AFTER
MIDNIGHT. WHILE THIS CANNOT BE RULED OUT...THERE IS NOT ENOUGH
CONFIDENCE IN ITS OCCURRENCE TO INCLUDE IN THE FORECAST JUST YET.
CLEARING SKIES AND LIGHT WINDS TONIGHT SHOULD ALLOW FOR GOOD
RADIATIONAL COOLING WITH LOWS JUST BELOW ZERO NORTHWEST TO AROUND
10 IN THE SOUTHEAST. THE SURFACE RIDGE AXIS WILL BE EAST OF THE
AREA BY 12Z SUNDAY WITH SOUTH WINDS INCREASING DURING THE DAY AS THE
RIDGE CONTINUES TO MOVE EAST AND A COLD FRONT MOVES INTO NORTHWEST
IOWA. HIGH CLOUDS WILL ALSO BE ON THE INCREASE. TEMPERATURES WILL
BE A CHALLENGE TOMORROW WITH MODELS SHOWING A SHALLOW BUT STRONG
INVERSION OVER THE AREA. HIGHS IN THE MID 20S NORTH TO LOW 30S SOUTH
WERE BASED ON THE SHALLOW MIXING. IF WINDS ARE STRONGER THAN
FORECAST THEN...MIXING WILL BE DEEPER AND THE FORECAST HIGHS WILL BE
ON THE COLD SIDE. DLF
LONG TERM...MONDAY THROUGH SATURDAY
TWO MAIN CONCERNS IN THIS TIME FRAME ARE THE WEAK CYCLOGENESIS
EVENT WHICH COULD BRING PRECIP TO THE SOUTH LATE MONDAY AND EARLY
TUESDAY...AND THE MUDDLE AMONGST THE MODELS WITH THE UPPER AIR
PATTERN AND SUBSEQUENT DETAILS MIDWEEK.
REGARDING THE MONDAY EVENT...THE NAM IS MORE VIGOROUS AND FURTHER
NORTH WITH DEVELOPING THE LOW THAN THE GFS AND ECMWF...WHICH ARE
WEAKER AND FURTHER SOUTH. HAVE SHADED POPS TO FAVOR THE GFS/ECMWF
SOLUTIONS AND KEPT QPF/SNOW ON THE LIGHT SIDE.
AT MID WEEK...THE EXTENDED MODELS ARE INCONSISTENT AMONG
THEMSELVES AND FROM RUN TO RUN IN HANDLING THE COMPLEX SPLIT FLOW
PATTERN WHICH INCLUDES A SOUTHWEST U.S. CUTOFF AND AN ACTIVE
NORTHERN STREAM. THE 12Z ECMWF MOVES A CLIPPER SYSTEM TO OUR
NORTHEAST WEDNESDAY-THURSDAY...WHICH IS FURTHER NORTH AND EAST AT
THAN AT 00Z WHEN IT WAS PROGGED OVER OUR AREA. MEANWHILE...THE
12Z GFS PROGS THIS CLIPPER SYSTEM FASTER AND EVEN FURTHER
NORTHEAST...SO IT APPEARS THIS WOULD BE A NONEVENT FOR US.
THE GFS DOES HOLD MORE ENERGY BACK OVER THE NORTHERN ROCKIES WHICH
EVENTUALLY CUTS OFF AND DRIFTS ACROSS THE CENTRAL U.S. THROUGH
THE WEEKEND. HOWEVER...THIS GFS RUN IS AN OUTLIER RELATIVE TO THE 00Z
ENSEMBLE MEAN.
THUS FAITH IN ANY OF THESE SOLUTIONS IS LOW. HOWEVER...THE COMMON
THEME IS THAT TROUGHINESS DEVELOPS AND PROGRESSES THROUGH THE
CENTRAL U.S. LATE NEXT WEEK. THERE APPEARS TO BE NO SIGNIFICANT
PRECIP EVENT IN THIS TIME FRAME...AND INDICATIONS ARE THAT
REENFORCING COLD AIR MIGHT GIVE US OUR COLDEST TEMPS SO FAR THIS
SEASON SOMETIME LATE NEXT WEEK INTO THE WEEKEND. WOLF
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
554 AM CST FRI DEC 28 2012
.UPDATE...
12Z SOUNDING...CURRENTLY UNDERWAY...SO FAR CONTINUES TO SHOW A
DRY LAYER IN THE 800-850MB LAYER WHICH IS RESULTING IN MORE VIRGA
THAN PRECIPITATION. RADAR RETURNS THE PAST HOUR HAVE LIT UP WITH
RETURNS GENERALLY TO THE NORTH AND WEST OF THE QUAD CITIES. THESE
RETURNS INDICATE THE DRY LAYER IS SATURATING.
RECENT RAP TRENDS SHOW STRONG FORCING OVER THE NORTHERN CWFA. THE
DRY 800-850MB LAYER IS PREVENTING PRECIPITATION THERE BUT SAID
LAYER IS CLOSER TO SATURATION OVER THE WESTERN HALF. THIS FORCING
EXITS THE AREA BY MID MORNING LEAVING WEAK TO NEUTRAL LIFT BUT
MORE OF A SATURATED ATMOSPHERE. THUS THERE MAY BE A BRIEF SHOT OF
VERY LIGHT SNOW ONCE SATURATION IS ACHIEVED BEFORE GOING BACK TO
FLURRIES.
BY MID DAY THE RAP IS SHOWING VERY STRONG FORCING MOVING NORTH OUT
OF MISSOURI ASSOCIATED WITH A VORT MAX. IF CORRECT...THIS FORCING
SHOULD ALLOW LIGHT SNOW TO BREAK OUT ACROSS THE CWFA BEFORE IT
EXITS INTO MN/WI BY MID AFTERNOON. HOWEVER...BY THIS TIME THE
INVERTED TROF IS COMING INTO PLAY SO LIGHT SNOW SHOULD CONTINUE
ACROSS THE CWFA INTO LATE AFTERNOON/EVENING.
AMOUNTS ARE STILL QUESTIONABLE BUT THE INITIAL 0.5 TO 1 INCH
ALONG/NORTH OF HWY 30 STILL LOOKS REASONABLE. THE TRACE TO 0.5
INCH SOUTH OF HWY 30 MAY BE OVERLY GENEROUS BUT THERE SHOULD BE AT
LEAST A DUSTING DOWN TO THE I-80 CORRIDOR.
AN UPDATE REFLECTING THESE TRENDS SHOULD BE AVAILABLE WITHIN 30 TO
60 MINUTES. ..08..
&&
.AVIATION...
A LAYER OF DRY AIR FROM 4.5 TO 6.0 KFT AGL IS HOLDING BACK THE
DEVELOPMENT OF -SN. RADAR RETURNS DO SHOW SATURATION TAKING PLACE
SO MVFR/VFR CONDITIONS SHOULD CONTINUE AT KDBQ/KCID WITH VFR AT
KMLI/KBRL. RAP MODEL TRENDS INDICATE STRONG FORCING MOVING NORTH
OUT OF MISSOURI BY 18Z/28 WHICH SHOULD SATURATE THE ATMOSPHERE AND
ALLOW -SN TO DVLP. THUS EXPECT CONDITIONS TO DETERIOTE TO IFR AND
POSSIBLY LIFR. KCID/KDBQ WILL HAVE THE BETTER CHANCES AT LIFR.
CONDITIONS TO SLOWLY IMPROVE TO MVFR AFT 03Z/29. ..08..
&&
.PREV DISCUSSION... /ISSUED 304 AM CST FRI DEC 28 2012/
SYNOPSIS...
06Z SFC ANALYSIS HAS A WEAK LOW NORTHEAST OF KEMP WITH A DIFFUSE
FRONT RUNNING ACROSS NORTHERN MISSOURI AND INTO SOUTHERN ILLINOIS. A
WEAK TROF RAN FROM NORTHEAST IOWA INTO NORTHERN INDIANA WHILE AN
INVERTED TROF RAN FROM THE KANSAS LOW INTO THE EASTERN DAKOTAS. DEW
POINTS WERE IN THE TEENS AND 20S ACROSS MUCH OF THE MIDWEST WITH 30S
AND 40S IN THE SOUTHERN PLAINS AND DEEP SOUTH.
SHORT TERM...TODAY AND TONIGHT...
BASED ON SFC REPORTS...THE RADAR RETURNS ARE INDICATING MORE VIRGA
THAN WHAT IS ACTUALLY REACHING THE GROUND. THE MECHANISM FOR
GENERATING THE -SN IS NOT OBVIOUS BUT APPEARS TO BE TIED TO THE
NARROW LAYER OF DRY AIR ON THE 00Z SOUNDING.
RAP TRENDS ALONG WITH THE OTHER MODELS INDICATE SATURATION IN THE
800-850MB LAYER WILL OCCUR DURING THE DAY ALLOWING CONDENSATION
PRESSURE DEFICITS IN THIS LAYER TO COLLAPSE. ALTHOUGH THE FORCING IS
NOT GREAT IT WILL BE ENOUGH TO GENERATE LIGHT SNOW.
THE INVERTED TROF COMPLICATES THINGS FURTHER SINCE INVERTED TROFS
ARE NOTORIOUS FOR SURPRISES. BASED ON RAP TRENDS SAID INVERTED TROF
WILL SLOWLY MOVE ACROSS THE CWFA DURING THE DAY. THUS THE BETTER
SNOW SHOULD BE SEEN IN ADVANCE AND IMMEDIATELY AROUND THE INVERTED
TROF WITH PRECIPITATION INTENSITY DECREASING ONCE THE INVERTED TROF
GOES BY.
TONIGHT...LIGHT SNOW WILL CONTINUE INTO THE EVENING HOURS BEFORE
SLOWLY TAPERING OFF. VERY LIGHT SNOW OR FLURRIES IS EXPECTED TO
CONTINUE UNTIL NEARLY SUNRISE.
MOISTURE IS LIMITED AND THE MAIN FORCING FEATURES ARE ALSO QUITE
WEAK. HOWEVER...ADDING THE INVERTED TROF TO EVERYTHING SHOULD RESULT
IN MEASURABLE SNOWFALL ACROSS A MAJORITY OF THE CWFA. AMOUNTS OF 0.5
TO 1 INCH SHOULD BE SEEN FROM ABOUT HWY 30 ON NORTH WITH A TRACE TO
0.5 INCHES OF ACCUMULATION SOUTH OF HWY 30. ..08..
LONG TERM...SATURDAY THROUGH THURSDAY...
THE BULK OF THE LIGHT SNOW SHOULD BE EAST OF THE FORECAST AREA EARLY
SATURDAY MORNING. HOWEVER...MODELS ARE SHOWING A SECOND SHORT WAVE
OVER WESTERN IOWA/MISSOURI EARLY SATURDAY. HAVE HELD ONTO SOME
FLURRIES IN THE EAST WITH THIS MID LEVEL FEATURE MOVING THROUGH BY
18Z SATURDAY. COLD TEMPERATURES WILL OVERSPREAD THE AREA SATURDAY
NIGHT WITH SURFACE AND UPPER RIDGING MOVING THROUGH THE REGION.
MODELS ARE SUGGESTING THAT THE SURFACE RIDGE AXIS WILL BE OVER THE
FORECAST AREA AT 06Z AND EAST OF THE CWFA BY 12Z SO WE SHOULD SEE
SOME LIGHT RETURN FLOW DEVELOPING AFTER MIDNIGHT. WITH SOUTH WINDS
DEVELOPING LATE...KEPT OVERNIGHT LOWS IN THE SINGLE DIGITS ABOVE
ZERO NORTH TO AROUND 15 IN THE FAR SOUTH.
FOR THE BEGINNING OF THE WORK WEEK A SOUTHERN STREAM SYSTEM WILL
MOVE OUT OF THE SOUTHWEST U.S. INTO THE LOWER MISSISSIPPI VALLEY
MONDAY AND MONDAY NIGHT. THE NORTHERN EDGE OF THE PRECIPITATION
SHIELD IS PROGGED TO BRUSH THE SOUTHERN COUNTIES MONDAY AND MONDAY NIGHT.
TEMPERATURES WILL BE COLD ENOUGH FOR THIS PRECIPITATION TO BE ALL
SNOW. HOWEVER...THE SNOW WILL BE LIGHT AND SHOULD NOT AMOUNT TO
MUCH ACCUMULATION BY TUESDAY MORNING.
NORTHWEST FLOW DEVELOPS OVER THE UPPER MIDWEST BY LATE TUESDAY WITH
GOOD AGREEMENT AMONG THE LONG RANGE MODELS ON A SHORT WAVE DROPPING
SOUTHEAST THROUGH REGION WEDNESDAY NIGHT AND THURSDAY. THE SYSTEM
WILL BE ENCOUNTERING A DRY AIRMASS AND SHOULD NOT PRODUCE ANY
PRECIPITATION. HOWEVER IT WILL DRAG A COLD AIRMASS SOUTH INTO THE
MID MISSISSIPPI VALLEY BY THURSDAY. HAVE OPTED FOR THE COLDER
GUIDANCE FOR THURSDAY/S TEMPERATURES.
DLF
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
304 AM CST FRI DEC 28 2012
.SYNOPSIS...
06Z SFC ANALYSIS HAS A WEAK LOW NORTHEAST OF KEMP WITH A DIFFUSE
FRONT RUNNING ACROSS NORTHERN MISSOURI AND INTO SOUTHERN ILLINOIS. A
WEAK TROF RAN FROM NORTHEAST IOWA INTO NORTHERN INDIANA WHILE AN
INVERTED TROF RAN FROM THE KANSAS LOW INTO THE EASTERN DAKOTAS. DEW
POINTS WERE IN THE TEENS AND 20S ACROSS MUCH OF THE MIDWEST WITH 30S
AND 40S IN THE SOUTHERN PLAINS AND DEEP SOUTH.
&&
.SHORT TERM...TODAY AND TONIGHT...
BASED ON SFC REPORTS...THE RADAR RETURNS ARE INDICATING MORE VIRGA
THAN WHAT IS ACTUALLY REACHING THE GROUND. THE MECHANISM FOR
GENERATING THE -SN IS NOT OBVIOUS BUT APPEARS TO BE TIED TO THE
NARROW LAYER OF DRY AIR ON THE 00Z SOUNDING.
RAP TRENDS ALONG WITH THE OTHER MODELS INDICATE SATURATION IN THE
800-850MB LAYER WILL OCCUR DURING THE DAY ALLOWING CONDENSATION
PRESSURE DEFICITS IN THIS LAYER TO COLLAPSE. ALTHOUGH THE FORCING IS
NOT GREAT IT WILL BE ENOUGH TO GENERATE LIGHT SNOW.
THE INVERTED TROF COMPLICATES THINGS FURTHER SINCE INVERTED TROFS
ARE NOTORIOUS FOR SURPRISES. BASED ON RAP TRENDS SAID INVERTED TROF
WILL SLOWLY MOVE ACROSS THE CWFA DURING THE DAY. THUS THE BETTER
SNOW SHOULD BE SEEN IN ADVANCE AND IMMEDIATELY AROUND THE INVERTED
TROF WITH PRECIPITATION INTENSITY DECREASING ONCE THE INVERTED TROF
GOES BY.
TONIGHT...LIGHT SNOW WILL CONTINUE INTO THE EVENING HOURS BEFORE
SLOWLY TAPERING OFF. VERY LIGHT SNOW OR FLURRIES IS EXPECTED TO
CONTINUE UNTIL NEARLY SUNRISE.
MOISTURE IS LIMITED AND THE MAIN FORCING FEATURES ARE ALSO QUITE
WEAK. HOWEVER...ADDING THE INVERTED TROF TO EVERYTHING SHOULD RESULT
IN MEASURABLE SNOWFALL ACROSS A MAJORITY OF THE CWFA. AMOUNTS OF 0.5
TO 1 INCH SHOULD BE SEEN FROM ABOUT HWY 30 ON NORTH WITH A TRACE TO
0.5 INCHES OF ACCUMULATION SOUTH OF HWY 30. ..08..
.LONG TERM...SATURDAY THROUGH THURSDAY...
THE BULK OF THE LIGHT SNOW SHOULD BE EAST OF THE FORECAST AREA EARLY
SATURDAY MORNING. HOWEVER...MODELS ARE SHOWING A SECOND SHORT WAVE
OVER WESTERN IOWA/MISSOURI EARLY SATURDAY. HAVE HELD ONTO SOME
FLURRIES IN THE EAST WITH THIS MID LEVEL FEATURE MOVING THROUGH BY
18Z SATURDAY. COLD TEMPERATURES WILL OVERSPREAD THE AREA SATURDAY
NIGHT WITH SURFACE AND UPPER RIDGING MOVING THROUGH THE REGION.
MODELS ARE SUGGESTING THAT THE SURFACE RIDGE AXIS WILL BE OVER THE
FORECAST AREA AT 06Z AND EAST OF THE CWFA BY 12Z SO WE SHOULD SEE
SOME LIGHT RETURN FLOW DEVELOPING AFTER MIDNIGHT. WITH SOUTH WINDS
DEVELOPING LATE...KEPT OVERNIGHT LOWS IN THE SINGLE DIGITS ABOVE
ZERO NORTH TO AROUND 15 IN THE FAR SOUTH.
FOR THE BEGINNING OF THE WORK WEEK A SOUTHERN STREAM SYSTEM WILL
MOVE OUT OF THE SOUTHWEST U.S. INTO THE LOWER MISSISSIPPI VALLEY
MONDAY AND MONDAY NIGHT. THE NORTHERN EDGE OF THE PRECIPITATION
SHIELD IS PROGGED TO BRUSH THE SOUTHERN COUNTIES MONDAY AND MONDAY NIGHT.
TEMPERATURES WILL BE COLD ENOUGH FOR THIS PRECIPITATION TO BE ALL
SNOW. HOWEVER...THE SNOW WILL BE LIGHT AND SHOULD NOT AMOUNT TO
MUCH ACCUMULATION BY TUESDAY MORNING.
NORTHWEST FLOW DEVELOPS OVER THE UPPER MIDWEST BY LATE TUESDAY WITH
GOOD AGREEMENT AMONG THE LONG RANGE MODELS ON A SHORT WAVE DROPPING
SOUTHEAST THROUGH REGION WEDNESDAY NIGHT AND THURSDAY. THE SYSTEM
WILL BE ENCOUNTERING A DRY AIRMASS AND SHOULD NOT PRODUCE ANY
PRECIPITATION. HOWEVER IT WILL DRAG A COLD AIRMASS SOUTH INTO THE
MID MISSISSIPPI VALLEY BY THURSDAY. HAVE OPTED FOR THE COLDER
GUIDANCE FOR THURSDAY/S TEMPERATURES.
DLF
&&
.AVIATION... /ISSUED 1108 PM CST THU DEC 27 2012/
LIGHT EAST WINDS AND STRATUS AT THE BORDERLINE BETWEEN MVFR/IFR WILL
CONTINUE THROUGH ABOUT 14Z FRIDAY...WITH CIGS OF 900 TO 2000 FT. LIGHT
EAST WINDS WILL CONTINUE TO FRIDAY AFTERNOON. LIGHT SNOW AND FOG SHOULD
MOVE INTO ALL SITES AROUND 10Z-14Z FRIDAY. THOUGH SNOW SHOULD BE
MAINLY LIGHT...MODELS DO SUGGEST A LOWERING OF VISIBILITY THROUGH
FOG TO POSSIBLY UNDER A MILE FOR MUCH OF THE DAY AND EVENING. ALONG WITH
THAT FOG...CIGS SHOULD DROP TO LESS THAN 1000 FT FOR MOST THE DAY
FRIDAY AND FRIDAY EVENING. FOR NOW...WILL GO WITH 1SM VISIBILITY IN FOG
AND LIGHT SNOW...AGAIN RESTRICTED BY FOG MORE THAN SNOW IN
REALITY. WINDS MAY BECOME CALM AFTER 18Z FRIDAY...THROUGH EARLY
FRIDAY EVENING BEFORE A 03Z SWITCH TO NORTHWEST AS THE WEAK LOW
PRESSURE SYSTEM MOVES INTO ILLINOIS.
ERVIN
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS TOPEKA KS
344 AM CST FRI DEC 28 2012
.DISCUSSION...
ROUND OF CLOUDS AND LIGHT FREEZING DRIZZLE OR SNOW COMING TO THE
AREA AS AN UPPER LONGWAVE TROF MOVES EASTWARD OUT OF THE ROCKIES
TODAY. TEMPERATURES HAVE HELD AROUND THE FREEZING MARK ALONG AND SW
OF THE INCOMING LOW...WITH CHILLY SINGLE DIGIT TEMPERATURES NOTED
OUT ON THE HIGH PLAINS.
TODAY/TONIGHT...CAA CONTINUES THROUGHOUT THE DAY TODAY AS UPPER
TROF PASSES OVER THE STATE IN PHASES AND PUSHES COLD AIR SOUTHWARD
AS IT DOES SO. HIGHS TODAY NOT EXPECTED TO BE MORE THAN THE 20S IT
IS NOW AT MANY LOCATIONS ALONG AND SE OF THE INTERSTATE. OVERNIGHT
LOWS TONIGHT INTO SATURDAY EXPECTED TO BE QUITE CHILLY WITH SINGLE
DIGITS COMMON FOR MUCH OF THE FORECAST AREA. RETURN OF THE UPPER
RIDGE TO THE HIGH PLAINS INTO SATURDAY AFTERNOON MAY MAKE FOR A
WARMER WEEKEND WITH HIGHS NEAR THE FREEZING MARK SATURDAY AND EVEN
WARMER ON SUNDAY.
MON-TUES...NEXT UPPER TROFS PROGGED OVER THE NORTHERN PLAINS WITH
THE SOUTHERN PORTION SOUTHWARD OVER THE FOUR CORNERS REGION.
SOUTHERN WAVE ADVECT WARMER TEMPERATURES AND MOISTURE WELL INTO
THE CENTRAL PLAINS FOR MONDAY MORNING...BEFORE IT BECOMES A BATTLE
FOR HOW QUICKLY THE NEXT ROUND OF COLD AIR CAN MOVE SOUTHWARD AS
THE NORTHERN STREAM PASSES ACROSS THE HIGH PLAINS. COLUMN
SATURATES TOP DOWN AND CURRENTLY WOULD EXPECT SNOW FROM THE
PROFILE. PERHAPS MIXED WITH RAIN WHERE HIGHS ARE WARMER. EC TAKES
SOUTHERN PORTION OF THE TROF AND SHEARS IT OUT ACROSS THE HIGH
PLAINS AND WOULD THEREFORE LINGER PRECIPITATION INTO TUESDAY. MAY
SEE A FEW INCHES OF SNOW FROM THIS STORM BUT WILL NEED TO MONITOR
FOR POSSIBLE PRECIP TYPE CHANGES WITH STORM TRACK.
WED/THURS MAY PAN OUT TO BE PRETTY CHILLY DAYS AS NORTH TO
NORTHWEST FLOW SETS UP BYE THE MIDDLE OF NEXT WEEK. 67
&&
.AVIATION...
OBS UPSTREAM HAVE SHOWN CIGS IMPROVING UPSTREAM AND BEHIND THE
SURFACE TROUGH AXIS. HOWEVER RAP AND NAM FORECAST SOUNDINGS CONTINUE
TO SUGGEST MVFR CIGS DEVELOPING BY MID MORNING. WILL BE A LITTLE
MORE OPTIMISTIC WITH THIS FORECAST BASED ON LATEST TRENDS IN OBS
UPSTREAM AND KEEP CIGS BETWEEN 2 AND 3 KFT AND MOVING IN A LITTLE
LATER BETWEEN 09Z AND 12Z. BECAUSE THE UPPER TROUGH AND SURFACE LOW
ARE SLOW TO MOVE EAST...MODELS CONTINUE TO WRAP MOISTURE AROUND INTO
NORTHEAST KS...SO WILL HOLD ONTO THE MVFR CIGS THROUGH 06Z. SEE
DISCUSSION ABOVE FOR FURTHER DETAILS.
WOLTERS
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS WICHITA KS
1138 PM CST THU DEC 27 2012
.AVIATION...06Z TAFS KRSL/KSLN/KHUT/KICT/KCNU
THE MAIN AVIATION CONCERN WILL BE THE LOW MVFR CEILINGS EXPECTED
THROUGH THE EARLY PORTION OF THE FORECAST PERIOD.
DIFFICULT FORECAST OVERNIGHT...WITH MVFR CONDITIONS AT MOST
LOCATIONS EXCEPT KICT/KCNU. WILL CONTINUE THE PESSIMISTIC FORECAST
AT ALL TAF SITES...HAVING MVFR CEILINGS THROUGH MUCH OF THE
FORECAST.
DO NOT SEE AN AREA FOR THE CEILINGS TO IMPROVE MUCH UNTIL DRIER AIR
FILTERS INTO THE LOW LEVELS BEHIND THE NEXT WAVE DURING THE DAY ON
FRIDAY. THIS WILL LEAD TO ALL TAF SITES IMPROVING TO VFR CEILINGS
WITH THE BKN-OVC SKIES CONTINUING.
KETCHAM
&&
.PREV DISCUSSION... /ISSUED 854 PM CST THU DEC 27 2012/
UPDATE...
GONNA SEND OUT A QUICK UPDATE TO CHANGE MENTION OF FREEZING DRIZZLE
POTENTIAL FOR SOUTHEAST KS...TO MORE OF A PATCHY FREEZING DRIZZLE
CHANCE. NOT EXPECTING A WIDESPREAD FREEZING DRIZZLE EVENT...AS
LATEST SHORT TERM MODEL SOUNDINGS NOT SHOWING NEAR ENOUGH SATURATION
IN THE LOWEST 1000 FEET FOR A WIDESPREAD DRIZZLE CHANCE. BUT SOME
SATURATION MAY EXIST IN THE 1000-3000 FOOT LAYER FOR SOME PATCHY
DRIZZLE TO FORM...WHICH WOULD FREEZE ON CONTACT GIVEN THE FORECASTED
BELOW FREEZING SFC TEMPS ACROSS SOUTHEAST KS. LATEST RUC SOUNDINGS
ALSO SUGGEST SOME PATCHY FREEZING FOG JUST AHEAD OF THE SURFACE
TROUGH AS IT PUSHES INTO SE KS BY AROUND 12Z/FRI. SO WILL MENTION
THIS CHANCE AS WELL.
NOT EXPECTING WIDESPREAD TRAVEL ISSUES...WITH MAINLY SOME BRIDGES
AND OVERPASSES AFFECTED...SO WILL NOT ISSUE ANY KIND OF WINTER
WEATHER ADVISORY HEADLINE. BUT WILL HIT IT HARD IN THE HAZARDOUS
WEATHER OUTLOOK OR A SPECIAL WEATHER STATEMENT.
KETCHAM
PREV DISCUSSION... /ISSUED 543 PM CST THU DEC 27 2012/
AVIATION...00Z TAFS KRSL/KSLN/KHUT/KICT/KCNU
THE MAIN AVIATION CONCERN WILL BE THE LOW MVFR/IFR CONDITIONS
EXPECTED THROUGH MUCH OF THE FORECAST PERIOD.
DIFFICULT FORECAST TONIGHT...WITH MVFR CONDITIONS AT MOST LOCATIONS
EXCEPT KCNU. WILL CONTINUE THE PESSIMISTIC FORECAST AT ALL TAF
SITES...HAVING MVFR/IFR THROUGH MUCH OF THE FORECAST. WITH SOME IFR
CEILINGS FOR KSLN AND KCNU AFTER FRI/05Z. NOT ALOT OF CONFIDENCE IN
THIS IFR CLOUD DECK...AND COULD ACTUALLY SEE SOME LIFR CEILINGS
DEVELOP.
DO NOT SEE AN AREA FOR THE CEILINGS TO IMPROVE MUCH UNTIL DRIER AIR
FILTERS INTO THE LOW LEVELS BEHIND THE NEXT WAVE DURING THE DAY ON
FRIDAY. THIS WILL LEAD TO ALL TAF SITES IMPROVING TO VFR CEILINGS
WITH THE BKN-OVC SKIES CONTINUING.
KETCHAM
PREV DISCUSSION... /ISSUED 312 PM CST THU DEC 27 2012/
DISCUSSION...
TONIGHT-FRIDAY:
UPPER TROUGH WILL CONTINUE PUSHING EASTWARD ACROSS THE CENTRAL
PLAINS. THIS WILL ALLOW THE POLAR AIR TO PUSH BACK SOUTHEASTWARD
ACROSS OUR FORECAST AREA. INITIAL PV ANOMALY IS ALREADY WELL NORTH
OF THE AREA OVER NEBRASKA/SOUTH DAKOTA. MEASURABLE SNOW WILL
THEREFORE REMAIN WELL NORTHEAST OF OUR AREA. ANOTHER PV ANOMALY WILL
TRACK IN THE BASE OF THE TROUGH ACROSS THE SOUTHERN PLAINS TONIGHT
INTO FRIDAY. WE DO EXPECT PRESENT AREA OF LOW CLOUDS NEAR AND
NORTHWEST OF SURFACE LOW...TO CONTINUE TO WRAP BACK INTO OUR AREA
OVERNIGHT INTO FRIDAY MORNING BEHIND THE LOW TRACK. THERE COULD BE
PATCHY LIGHT FREEZING DRIZZLE/FOG DEVELOPING IN THE SOUTHEAST
COUNTIES LATE TONIGHT/EARLY FRIDAY WITH SLIGHTLY DEEPER LOW-LEVEL
MOISTURE IN THE SOUNDING DATA AND WEAK ISENTROPIC
UPGLIDE...COINCIDENT WITH WEAK SOUTHERLY FLOW AHEAD OF THE COLD
FRONT. HOWEVER...PROBABILITIES SEEM TO BE MORE OPTIMAL JUST TO OUR
EAST/SOUTHEAST. BREEZY NORTHWESTERLY WINDS SHOULD HELP SCOUR OUT
LOW CLOUDS FRIDAY WITH A CLEAR/COLD NIGHT SLATED FOR FRIDAY NIGHT.
SATURDAY-SUNDAY:
UPPER LOW WILL BE IN THE PROCESS OF DEVELOPING OVER THE
SOUTHWEST...WHILE SURFACE POLAR HIGH SHIFTS EASTWARD OUT OF THE
SOUTHERN PLAINS. RELATIVELY LIGHT WESTERLY COMPONENT SATURDAY WILL
BACK TO SOUTH-SOUTHWESTERLY SATURDAY NIGHT WITH SPEEDS INCREASING TO
BREEZY LEVELS SUNDAY. EXPECTING FULL SUNSHINE SATURDAY WITH PERHAPS
SOME HIGH CLOUDS PUSHING IN FROM THE SOUTHWEST ON SUNDAY.
OTHERWISE...EXPECTING MODERATING TEMPERATURES TO NEAR CLIMATOLOGY.
MONDAY-THURSDAY:
MEDIUM RANGE MODELS HAVE COME INTO AGREEMENT ON AN INITIAL SHORTWAVE/PV
ANOMALY EJECTING OUT OF THE SOUTHWEST UPPER LOW...ACROSS
KANSAS/OKLAHOMA MONDAY INTO MONDAY NIGHT. IN ADDITION...COLDER AIR
ASSOCIATED WITH ENERGY IN THE NORTHERN BRANCH JET STREAM...WILL
INFILTRATE SOUTHWARD THROUGH OUR AREA. A CONSERVATIVE CHANCE OF RAIN
TO SNOW APPEARS REASONABLE AREA-WIDE...WITH RELATIVELY HIGHER
PROBABILITIES IN THE SOUTHEAST COUNTIES. IF LATER MODEL RUNS
CONTINUE TO SHOW THIS SCENARIO...PROBABILITIES OF PRECIPITATION WILL
LIKELY BE INCREASED IN FORTHCOMING FORECASTS ESPECIALLY IN THE
SOUTH. THE MAIN UPPER LOW MAY REMAIN SUPPRESSED OVER THE SOUTHWEST
INTO MIDWEEK BASED ON THE ECMWF/CANADIAN WHILE LOW-LEVEL HIGH
PRESSURE BUILDS INTO KANSAS. SO WILL MAINTAIN DRY FORECAST FOR
TUESDAY-THURSDAY. TEMPERATURES ARE PROJECTED TO BE NEAR TO SLIGHTLY
BELOW CLIMATOLOGY DURING THE PERIOD. FORECAST CONFIDENCE IS ONLY
LOW-MEDIUM GIVEN THE GFS ENSEMBLES SHOW DECENT SPREAD/UNCERTAINTY IN
BOTH THE NORTHERN BRANCH AND SOUTHERN BRANCH JETSTREAMS IN THE SPLIT
UPPER PATTERN.
JMC
&&
.PRELIMINARY POINT TEMPS/POPS...
WICHITA-KICT 17 30 12 40 / 10 10 0 0
HUTCHINSON 14 26 11 37 / 10 10 0 0
NEWTON 17 27 12 37 / 10 10 0 0
ELDORADO 19 29 11 38 / 10 10 0 0
WINFIELD-KWLD 22 32 13 40 / 10 10 0 0
RUSSELL 8 22 5 36 / 10 0 0 0
GREAT BEND 10 23 8 38 / 10 0 0 0
SALINA 14 24 9 35 / 10 10 0 0
MCPHERSON 14 26 10 36 / 10 10 0 0
COFFEYVILLE 25 34 16 39 / 10 10 0 0
CHANUTE 24 32 15 37 / 10 10 0 0
IOLA 24 31 16 36 / 10 10 0 0
PARSONS-KPPF 26 34 15 38 / 10 10 0 0
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1100 PM CST THU DEC 27 2012
.DISCUSSION...
THE LATEST RAP AND NAM MODEL SOUNDINGS CONTINUE TO SUGGEST SOME MVFR
CIGS MOVING IN BEHIND THE INVERTED TROUGH AXIS...ALTHOUGH A LITTLE
BIT SLOWER THAN EARLIER RUNS. BECAUSE OF THIS AND THE OVERCAST SKIES
LIKELY TO PERSIST THROUGH THE MORNING ACROSS THE AREA...HAVE ALREADY
UPDATED THE FORECAST TO WARM MIN TEMPS UP A COUPLE DEGREES. ALSO THE
RAP AND NAM SHOW LITTLE IF ANY VERTICAL MOTION WITHIN THE STRATUS
DECK WITH ISENTROPIC SURFACES SHOWING DOWNGLIDE DEVELOPING BEHIND
THE WIND SHIFT. WITH NO REAL LARGE SCALE OR MESOSCALE FORCING TO
POINT TO...HAVE REMOVED POPS AND ONLY MENTIONED FLURRIES OR A SLIGHT
CHANCE FOR FREEZING DRIZZLE. THIS WOULD LIKELY ONLY OCCUR FOR A
BRIEF PERIOD OF TIME OVER ISOLATED SPOTS.
&&
.AVIATION...
OBS UPSTREAM HAVE SHOWN CIGS IMPROVING UPSTREAM AND BEHIND THE
SURFACE TROUGH AXIS. HOWEVER RAP AND NAM FORECAST SOUNDINGS CONTINUE
TO SUGGEST MVFR CIGS DEVELOPING BY MID MORNING. WILL BE A LITTLE
MORE OPTIMISTIC WITH THIS FORECAST BASED ON LATEST TRENDS IN OBS
UPSTREAM AND KEEP CIGS BETWEEN 2 AND 3 KFT AND MOVING IN A LITTLE
LATER BETWEEN 09Z AND 12Z. BECAUSE THE UPPER TROUGH AND SURFACE LOW
ARE SLOW TO MOVE EAST...MODELS CONTINUE TO WRAP MOISTURE AROUND INTO
NORTHEAST KS...SO WILL HOLD ONTO THE MVFR CIGS THROUGH 06Z. SEE
DISCUSSION ABOVE FOR FURTHER DETAILS.
WOLTERS
&&
.PREV DISCUSSION... /333 PM CST THU DEC 27 2012/
TONIGHT THROUGH FRIDAY...MAIN FOCUS FOR THE SHORT TERM IS ON THE
IMPACTS OF THE PASSING UPPER LEVEL TROUGH TONIGHT THROUGH FRIDAY
MORNING. AS OF 21Z...THE UPPER LEVEL TROUGH WAS SWEEPING ACROSS THE
NORTHERN AND CENTRAL PLAINS WITH THE SURFACE LOW OVER NORTHEAST NEW
MEXICO. THE PRECIPITATION ASSOCIATED WITH THIS SYSTEM HAS GENERALLY
STAYED NORTH OF THE KANSAS/NEBRASKA BORDER...WITH LIGHT SNOW BEING
REPORTED ACROSS MUCH OF NEBRASKA THROUGH THE DAY.
AN UPPER LEVEL RIDGE HAS BEGUN TO MOVE ONTO THE PACIFIC
COASTLINE...WHICH WILL HELP TO PUSH THE TROUGH ALMOST DUE EAST OVER
THE NORTHERN PLAINS THROUGH THE EVENING AND OVERNIGHT HOURS. SOME
LIGHT PRECIPITATION MAY STILL BE ABLE TO SKIM ALONG THE
KANSAS/NEBRASKA BORDER THIS EVENING AND OVERNIGHT WITH THIS EASTWARD
MOVING SYSTEM. THE BIG QUESTION WITH REGARDS TO PRECIPITATION
POTENTIAL WILL BE WITH THE AMOUNT OF AVAILABLE MOISTURE OVER THE
CWA. MODEL SOUNDINGS SHOW THE LOW LEVELS BECOMING FAIRLY SATURATED
UP TO AROUND 850MB OVERNIGHT ACROSS A MAJORITY OF THE CWA. THIS LOW
LEVEL MOISTURE COMBINED WITH SOME WEAK ISENTROPIC LIFT MAY BE ENOUGH
TO PRODUCE SOME PATCHY FREEZING DRIZZLE AND MAYBE A FEW FLURRIES.
MODEL SOUNDINGS SHOW THE LOW LEVEL MOISTURE INCREASING GENERALLY
BETWEEN 06Z-09Z AND REMAINING FAIRLY SATURATED THROUGH AROUND 15Z
BEFORE GRADUALLY DRYING OUT INTO THE EARLY AFTERNOON HOURS AS THE
TROUGH PASSES EAST OF THE AREA. ANY LIGHT SNOW SHOWERS THAT ARE ABLE
TO CLIP EXTREME NORTHERN KANSAS ARE NOT EXPECTED TO PRODUCE MORE
THAN A DUSTING OF ACCUMULATION...AND CURRENTLY DO NOT ANTICIPATE ANY
ICE ACCUMULATIONS WITH THE PATCHY FREEZING DRIZZLE.
WITH THE SURFACE LOW OVER NORTHEAST NEW MEXICO...A BOUNDARY
STRETCHED INTO NORTH CENTRAL KANSAS THIS AFTERNOON AND WILL
GRADUALLY SLIDE SOUTHWARD ACROSS THE CWA THROUGH THE EVENING
HOURS...CAUSING WINDS TO SHIFT FROM SOUTHEAST TO NORTHWEST. THIS
NORTHWESTERLY FLOW WILL LEAD TO CAA AND OVERNIGHT LOWS DROPPING INTO
THE LOW/MID 20S OVER EAST CENTRAL KANSAS AND PLUMMETING INTO THE
LOW/MID TEENS ACROSS NORTH CENTRAL AND CENTRAL KANSAS WHERE THE
BOUNDARY HAS ALREADY MOVED THROUGH. THESE NORTHWESTERLY WINDS WILL
PERSIST THROUGH FRIDAY AND COOL TEMPERATURES DOWN A BIT COMPARED TO
TODAY...WITH AFTERNOON HIGHS RANGING FROM LOW 20S OVER NORTH CENTRAL
KANSAS TO LOW 30S ACROSS EAST CENTRAL KANSAS.
ACH
FRIDAY EVENING THROUGH THURSDAY...UPPER LEVEL RIDGING BUILDS INTO
THE CENTRAL PLAINS FOR THE WEEKEND WITH DRY CONDITIONS EXPECTED. NOT
MUCH CHANGE WAS MADE TO THIS PERIOD AS MODELS ARE STILL IN AGREEMENT
WITH LIGHT WINDS BACKING TO THE WEST AND SOUTHWEST BY SUNDAY AS A
SURFACE TROUGH DEVELOPS OVER WESTERN KANSAS. THE TIGHTENING PRESSURE
GRADIENT WILL INCREASE SOUTHWEST WINDS BOOSTING HIGHS TO THE LOW AND
MID 40S ON SUNDAY.
THE WARMER AIR WILL BE SHORT LIVED HOWEVER AS EXTENDED MODELS ARE
BEGINNING TO PHASE TOGETHER ON MONDAY INTO MONDAY EVENING FOR THE
NEXT TROUGH TO IMPACT THE CWA. AN OPEN H5 WAVE FROM THE SOUTHWEST
LIFTS NORTHEAST INTO NEW MEXICO PHASING WITH A CANADIAN TROUGH
DIGGING SOUTHWARD THROUGH THE NORTHERN PLAINS. A COLD FRONT WILL
SURGE THROUGH THE AREA MONDAY DROPPING HIGHS BACK INTO THE
30S...POSSIBLY EVEN COLDER BUT HELD OFF LOWERING HIGHS TOO MUCH
JUST YET. BOTH THE ECMWF AND GFS CARRY SUFFICIENT GULF MOISTURE
NORTHWARD WITH SCATTERED LIGHT RAIN MIXED WITH SNOW...TRANSITIONING
TO ALL SNOW BY MONDAY EVENING. UNCERTAINTIES IN SNOWFALL AMOUNT
AND THE DISTURBANCE PLACEMENT ITSELF ARE TOO DIFFICULT TO
DETERMINE ATTM...HOWEVER RESIDENTS SHOULD MONITOR THIS SYSTEM OVER
THE UPCOMING DAYS WITH THE TIMING CURRENTLY ON NEW YEARS EVE.
SURFACE HIGH PRESSURE RETURNS THROUGH THE REMAINING PERIOD WITH
POSSIBLY A WEAK COLD FRONT AFFECTING THE AREA BY WEDNESDAY. HIGH
TEMPERATURES REMAIN BELOW NORMAL IN THE LOW 30S THROUGH THURSDAY.
BOWEN
&&
.TOP WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LAKE CHARLES LA
1237 PM CST FRI DEC 28 2012
.DISCUSSION...
FOR THE 18Z TAF PACKAGE.
&&
.AVIATION...
BKN BAND OF CONVCTN WORKING EAST TWD C CENTRAL LA...HAVING CLRD
KBPT-KLCH-KAEX. WILL CARRY TEMPO GROUPS AT KLFT-KARA FOR THIS
ACTIVITY...WITH THE TIMING A BEST ESTIMATE BASED ON LATEST RADAR
TRENDS. CONVECTION HAS RUN AHEAD OF THE ACTUAL COLD FRONT...ESPECIALLY
OVER CENTRAL LOUISIANA. CONSIDERABLE LOW CLOUD COVER EXTENDS WELL
INTO CENTRAL TX IN THE POST FRONTAL AIRMASS. DRY AIR COMING FROM
THE SOUTHWEST ALONG THE TX COAST AND INTO SE TX/SW LA CAUSING CIGS
TO BOUNCE AROUND A BIT...AND MAY PREVENT THE PREVAILING IFR
CURRENTLY AT KAEX. TIMING OF CLOUD COVER AND CIG HTS WERE BASED ON
A BLEND OF SATELLITE TRENDS AND MODEL FCST SOUNDINGS.
13
&&
.PREV DISCUSSION... /ISSUED 1008 AM CST FRI DEC 28 2012/
UPDATE...
LINE OF SHOWERS AND THUNDERSTORMS THAT EXTENDS FROM AVOYELLES
PARISH SOUTHWEST OFF THE SOUTHEAST TEXAS COAST IS A FRONTAL SYSTEM
THAT IS PUSHING THROUGH THE REGION THIS AM. TEMPS OUT AHEAD OF THE
FRONT ARE RUNNING IN THE UPPER 60S WITH TEMPS DROPPING INTO THE
UPPER 50S BEHIND THE FRONT. WINDS WILL SWING AROUND TO THE
NORTHWEST AND BE BRISK THROUGH THE AFTERNOON HOURS.
PREV DISCUSSION... /ISSUED 656 AM CST FRI DEC 28 2012/
AVIATION DISCUSSION...
FRONTAL WAVE LOW FOUND ACROSS THE LAKES REGION OF SOUTHEAST
TEXAS...WITH A WARM FRONT FROM SOUTHEAST THROUGH LAFAYETTE ..AND
A COLD FRONT FROM SOUTH THROUGH BEAUMONT.
THE WAVE LOW WILL TRAVEL EASTWARD...REACHING CENTRAL MISSISSIPPI
AROUND DUSK. ITS ATTENDANT COLD FRONT WILL SWEEP THROUGH THE
WESTERN UPPER GULF COAST STATES THIS AFTERNOON.
PRE-FRONTAL SHOWERS AND A FEW THUNDERSTORMS ARE EXPECTED IN THE
WARM SECTOR WEDGE...ENDING WITH PASSAGE OF COLD FRONT.
PREV DISCUSSION... /ISSUED 449 AM CST FRI DEC 28 2012/
DISCUSSION...SURFACE ANALYSIS SHOWING WARM FRONT GENERALLY JUST
INLAND OF COASTAL TEXAS AND SOUTHWEST LOUISIANA...ARCING JUST
OFFSHORE OF SOUTH CENTRAL LOUISIANA. ALONG AND NORTH OF
BOUNDARY. RADAR DEPICTING SCATTERED LIGHT TO MODERATE SHOWERS OVER
BOTH SOUTH TEXAS AND SOUTHWEST LOUISIANA. HAVE NOTED TEMPERATURES
GENERALLY RUNNING 20 TO 25 DEGREES ABOVE THAT OF 24 HOURS PRIOR.
LATEST VAD SHOWING A 40 KNOT LLJ ALREADY ESTABLISHED ABOVE LCH AT
850 MB TRANSPORTING IN VERY MOIST AND WARM AIR.
TODAY...WIDESPREAD SHOWERS AND A FEW THUNDERSTORMS ANTICIPATED AS
ASCENT IS ENHANCED WITH APPROACH OF PLAINS MID/UPPER LEVEL TROF.
LATEST RUC SUGGESTING SOUTH AND CENTRAL LOUISIANA WILL WARM SECTOR
AS A DEVELOPING TEXAS COAST SURFACE WAVE/WEAK LOW DEVELOPS...ADVANCING
INTO SOUTHWEST LOUISIANA BY LATE MORNING...AND EXITING NORTHEAST
BY LATE AFTERNOON WITH AN ACCOMPANYING COLD FRONT BEING DRUG WEST
TO EAST ACROSS THE AREA.
VERY IMPRESSIVE WIND FIELDS COMING TOGETHER AND GIVES PAUSE WHEN
INVESTIGATING. SOUTHERLY LLJ EXPECTED TO REMAIN OR STRENGTHEN
SLIGHTLY THROUGH THE REMAINDER OF THE MORNING WHILE MID LEVEL FLOW
VEERS TO SOUTHWEST AT 70-80 KTS...ENDING WITH A 120 WESTERLY JET ALOFT.
0-6 KM SHEAR VALUES PROGGED AT NEAR 70 KNOTS...WHILE LATEST RUC
COMING IN WITH PRE-FRONTAL HELICITY VALUES ABOVE 400 M2/S2. AT
THIS TIME SPC CARRYING AREA WITHIN A SEE TEXT NOTING A LACK OF
INSTABILITY. WOULD TAKE VERY LITTLE MORE TO SWING THE PENDULUM
TOWARD A SEVERE THREAT.
RAINS TAPER OFF WITH THE FRONTAL PASSAGE THIS AFTERNOON. WILL
MAINTAIN NO MORE THAN LOW END POPS INTO THIS EVENING OVER
ACADIANA.
WEEKEND...1030MB SURFACE HIGHS SETTLES INTO AREA WITH THE PASSAGE
OF THE FRONT WITH A DRY AND COOL WEATHER PATTERN SETTING UP. MAY
SEE OUR COOLEST MORNING THIS SEASON SUNDAY.
REMAINDER OF FORECAST...A SHALLOW COLD FRONT IS EXPECTED TO
ADVANCE INTO THE NORTHWEST GULF AND STALL. PRIMARILY SEEING AN
OVER-RUNNING RAIN EVENT POTENTIALLY SETTING UP ACROSS THE AREA FOR
MID-WEEK AS OUR NEXT TROF/LOW ADVANCES ACROSS THE PLAINS. GFS
CONTINUES TO BE FASTER AND WEAKER WITH THIS FEATURE COMPARED TO
THE ECMWF. HOPEFULLY FINER DETAILS WILL BE SORTED OUT OVER THE
NEXT FEW DAYS.
MARINE...STRONG SOUTHERLY WINDS WILL CONTINUE TODAY ASSOCIATED WITH AN
AN AREA OF LOW PRESSURE OVER THE WESTERN GULF OF MEXICO. THE LOW
WILL PULL A COLD FRONT ACROSS THE COASTAL WATERS BY FRIDAY EVENING
WITH A STRONG NORTHERLY FLOW DEVELOPING IN ITS WAKE.
&&
.PRELIMINARY POINT TEMPS/POPS...
KLCH 69 38 53 30 / 90 10 0 0
KBPT 68 36 51 31 / 40 10 0 0
KAEX 63 35 49 27 / 90 10 0 0
KLFT 72 41 52 30 / 90 20 0 0
&&
.LCH WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
TX...NONE.
GM...SMALL CRAFT ADVISORY UNTIL NOON CST SATURDAY FOR COASTAL WATERS
FROM CAMERON LA TO HIGH ISLAND TX OUT 20 NM-COASTAL WATERS
FROM INTRACOASTAL CITY TO CAMERON LA OUT 20 NM-COASTAL
WATERS FROM LOWER ATCHAFALAYA RIVER TO INTRACOASTAL CITY LA
OUT 20 NM-WATERS FROM INTRACOASTAL CITY TO CAMERON LA FROM
20 TO 60 NM-WATERS FROM CAMERON LA TO HIGH ISLAND TX FROM
20 TO 60 NM-WATERS FROM LOWER ATCHAFALAYA RIVER TO
INTRACOASTAL CITY LA FROM 20 TO 60 NM.
SMALL CRAFT EXERCISE CAUTION UNTIL 6 PM CST THIS EVENING FOR
CALCASIEU LAKE-SABINE LAKE-VERMILION BAY.
&&
$$
AREA FORECAST DISCUSSION
NWS LAKE CHARLES LA
1008 AM CST FRI DEC 28 2012
.UPDATE...
LINE OF SHOWERS AND THUNDERSTORMS THAT EXTENDS FROM AVOYELLES
PARISH SOUTHWEST OFF THE SOUTHEAST TEXAS COAST IS A FRONTAL SYSTEM
THAT IS PUSHING THROUGH THE REGION THIS AM. TEMPS OUT AHEAD OF THE
FRONT ARE RUNNING IN THE UPPER 60S WITH TEMPS DROPPING INTO THE
UPPER 50S BEHIND THE FRONT. WINDS WILL SWING AROUND TO THE
NORTHWEST AND BE BRISK THROUGH THE AFTERNOON HOURS.
&&
.PREV DISCUSSION... /ISSUED 656 AM CST FRI DEC 28 2012/
AVIATION DISCUSSION...
FRONTAL WAVE LOW FOUND ACROSS THE LAKES REGION OF SOUTHEAST
TEXAS...WITH A WARM FRONT FROM SOUTHEAST THROUGH LAFAYETTE ..AND
A COLD FRONT FROM SOUTH THROUGH BEAUMONT.
THE WAVE LOW WILL TRAVEL EASTWARD...REACHING CENTRAL MISSISSIPPI
AROUND DUSK. ITS ATTENDANT COLD FRONT WILL SWEEP THROUGH THE
WESTERN UPPER GULF COAST STATES THIS AFTERNOON.
PRE-FRONTAL SHOWERS AND A FEW THUNDERSTORMS ARE EXPECTED IN THE
WARM SECTOR WEDGE...ENDING WITH PASSAGE OF COLD FRONT.
PREV DISCUSSION... /ISSUED 449 AM CST FRI DEC 28 2012/
DISCUSSION...SURFACE ANALYSIS SHOWING WARM FRONT GENERALLY JUST
INLAND OF COASTAL TEXAS AND SOUTHWEST LOUISIANA...ARCING JUST
OFFSHORE OF SOUTH CENTRAL LOUISIANA. ALONG AND NORTH OF
BOUNDARY. RADAR DEPICTING SCATTERED LIGHT TO MODERATE SHOWERS OVER
BOTH SOUTH TEXAS AND SOUTHWEST LOUISIANA. HAVE NOTED TEMPERATURES
GENERALLY RUNNING 20 TO 25 DEGREES ABOVE THAT OF 24 HOURS PRIOR.
LATEST VAD SHOWING A 40 KNOT LLJ ALREADY ESTABLISHED ABOVE LCH AT
850 MB TRANSPORTING IN VERY MOIST AND WARM AIR.
TODAY...WIDESPREAD SHOWERS AND A FEW THUNDERSTORMS ANTICIPATED AS
ASCENT IS ENHANCED WITH APPROACH OF PLAINS MID/UPPER LEVEL TROF.
LATEST RUC SUGGESTING SOUTH AND CENTRAL LOUISIANA WILL WARM SECTOR
AS A DEVELOPING TEXAS COAST SURFACE WAVE/WEAK LOW DEVELOPS...ADVANCING
INTO SOUTHWEST LOUISIANA BY LATE MORNING...AND EXITING NORTHEAST
BY LATE AFTERNOON WITH AN ACCOMPANYING COLD FRONT BEING DRUG WEST
TO EAST ACROSS THE AREA.
VERY IMPRESSIVE WIND FIELDS COMING TOGETHER AND GIVES PAUSE WHEN
INVESTIGATING. SOUTHERLY LLJ EXPECTED TO REMAIN OR STRENGTHEN
SLIGHTLY THROUGH THE REMAINDER OF THE MORNING WHILE MID LEVEL FLOW
VEERS TO SOUTHWEST AT 70-80 KTS...ENDING WITH A 120 WESTERLY JET ALOFT.
0-6 KM SHEAR VALUES PROGGED AT NEAR 70 KNOTS...WHILE LATEST RUC
COMING IN WITH PRE-FRONTAL HELICITY VALUES ABOVE 400 M2/S2. AT
THIS TIME SPC CARRYING AREA WITHIN A SEE TEXT NOTING A LACK OF
INSTABILITY. WOULD TAKE VERY LITTLE MORE TO SWING THE PENDULUM
TOWARD A SEVERE THREAT.
RAINS TAPER OFF WITH THE FRONTAL PASSAGE THIS AFTERNOON. WILL
MAINTAIN NO MORE THAN LOW END POPS INTO THIS EVENING OVER
ACADIANA.
WEEKEND...1030MB SURFACE HIGHS SETTLES INTO AREA WITH THE PASSAGE
OF THE FRONT WITH A DRY AND COOL WEATHER PATTERN SETTING UP. MAY
SEE OUR COOLEST MORNING THIS SEASON SUNDAY.
REMAINDER OF FORECAST...A SHALLOW COLD FRONT IS EXPECTED TO
ADVANCE INTO THE NORTHWEST GULF AND STALL. PRIMARILY SEEING AN
OVER-RUNNING RAIN EVENT POTENTIALLY SETTING UP ACROSS THE AREA FOR
MID-WEEK AS OUR NEXT TROF/LOW ADVANCES ACROSS THE PLAINS. GFS
CONTINUES TO BE FASTER AND WEAKER WITH THIS FEATURE COMPARED TO
THE ECMWF. HOPEFULLY FINER DETAILS WILL BE SORTED OUT OVER THE
NEXT FEW DAYS.
MARINE...STRONG SOUTHERLY WINDS WILL CONTINUE TODAY ASSOCIATED WITH AN
AN AREA OF LOW PRESSURE OVER THE WESTERN GULF OF MEXICO. THE LOW
WILL PULL A COLD FRONT ACROSS THE COASTAL WATERS BY FRIDAY EVENING
.WITH A STRONG NORTHERLY FLOW DEVELOPING IN ITS WAKE.
&&
.PRELIMINARY POINT TEMPS/POPS...
KLCH 69 38 53 30 55 / 80 10 0 0 0
KBPT 68 36 51 31 54 / 80 10 0 0 0
KAEX 63 35 49 27 53 / 80 10 0 0 0
KLFT 72 41 52 30 55 / 80 20 0 0 0
&&
.LCH WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
TX...NONE.
GM...SMALL CRAFT ADVISORY UNTIL NOON CST SATURDAY FOR THE FOLLOWING
ZONES: COASTAL WATERS FROM CAMERON LA TO HIGH ISLAND TX OUT
20 NM...COASTAL WATERS FROM INTRACOASTAL CITY TO CAMERON LA
OUT 20 NM...COASTAL WATERS FROM LOWER ATCHAFALAYA RIVER TO
INTRACOASTAL CITY LA OUT 20 NM...WATERS FROM INTRACOASTAL
CITY TO CAMERON LA FROM 20 TO 60 NM...WATERS FROM CAMERON
LA TO HIGH ISLAND TX FROM 20 TO 60 NM...WATERS FROM LOWER
ATCHAFALAYA RIVER TO INTRACOASTAL CITY LA FROM 20 TO 60 NM.
SMALL CRAFT EXERCISE CAUTION UNTIL NOON CST TODAY FOR THE
FOLLOWING ZONES: VERMILION BAY.
&&
$$
AREA FORECAST DISCUSSION
NWS LAKE CHARLES LA
656 AM CST FRI DEC 28 2012
.AVIATION DISCUSSION...
FRONTAL WAVE LOW FOUND ACROSS THE LAKES REGION OF SOUTHEAST
TEXAS...WITH A WARM FRONT SPOKING SOUTHEAST THROUGH LAFAYETTE
...AND A COLD FRONT SPOKING SOUTH THROUGH BEAUMONT.
THE WAVE LOW WILL TRAVEL EASTWARD...REACHING CENTRAL MISSISSIPPI
AROUND DUSK. ITS ATTENDANT COLD FRONT WILL SWEEP THROUGH THE
WESTERN UPPER GULF COAST STATES THIS AFTERNOON.
PRE-FRONTAL SHOWERS AND A FEW THUNDERSTORMS ARE EXPECTED IN THE
WARM SECTOR WEDGE...ENDING WITH PASSAGE OF COLD FRONT.
&&
.PREV DISCUSSION... /ISSUED 449 AM CST FRI DEC 28 2012/
DISCUSSION...SURFACE ANALYSIS SHOWING WARM FRONT GENERALLY JUST
INLAND OF COASTAL TEXAS AND SOUTHWEST LOUISIANA...ARCING JUST
OFFSHORE OF SOUTH CENTRAL LOUISIANA. ALONG AND NORTH OF
BOUNDARY. RADAR DEPICTING SCATTERED LIGHT TO MODERATE SHOWERS OVER
BOTH SOUTH TEXAS AND SOUTHWEST LOUISIANA. HAVE NOTED TEMPERATURES
GENERALLY RUNNING 20 TO 25 DEGREES ABOVE THAT OF 24 HOURS PRIOR.
LATEST VAD SHOWING A 40 KNOT LLJ ALREADY ESTABLISHED ABOVE LCH AT
850 MB TRANSPORTING IN VERY MOIST AND WARM AIR.
TODAY...WIDESPREAD SHOWERS AND A FEW THUNDERSTORMS ANTICIPATED AS
ASCENT IS ENHANCED WITH APPROACH OF PLAINS MID/UPPER LEVEL TROF.
LATEST RUC SUGGESTING SOUTH AND CENTRAL LOUISIANA WILL WARM SECTOR
AS A DEVELOPING TEXAS COAST SURFACE WAVE/WEAK LOW DEVELOPS...ADVANCING
INTO SOUTHWEST LOUISIANA BY LATE MORNING...AND EXITING NORTHEAST
BY LATE AFTERNOON WITH AN ACCOMPANYING COLD FRONT BEING DRUG WEST
TO EAST ACROSS THE AREA.
VERY IMPRESSIVE WIND FIELDS COMING TOGETHER AND GIVES PAUSE WHEN
INVESTIGATING. SOUTHERLY LLJ EXPECTED TO REMAIN OR STRENGTHEN
SLIGHTLY THROUGH THE REMAINDER OF THE MORNING WHILE MID LEVEL FLOW
VEERS TO SOUTHWEST AT 70-80 KTS...ENDING WITH A 120 WESTERLY JET ALOFT.
0-6 KM SHEAR VALUES PROGGED AT NEAR 70 KNOTS...WHILE LATEST RUC
COMING IN WITH PRE-FRONTAL HELICITY VALUES ABOVE 400 M2/S2. AT
THIS TIME SPC CARRYING AREA WITHIN A SEE TEXT NOTING A LACK OF
INSTABILITY. WOULD TAKE VERY LITTLE MORE TO SWING THE PENDULUM
TOWARD A SEVERE THREAT.
RAINS TAPER OFF WITH THE FRONTAL PASSAGE THIS AFTERNOON. WILL
MAINTAIN NO MORE THAN LOW END POPS INTO THIS EVENING OVER
ACADIANA.
WEEKEND...1030MB SURFACE HIGHS SETTLES INTO AREA WITH THE PASSAGE
OF THE FRONT WITH A DRY AND COOL WEATHER PATTERN SETTING UP. MAY
SEE OUR COOLEST MORNING THIS SEASON SUNDAY.
REMAINDER OF FORECAST...A SHALLOW COLD FRONT IS EXPECTED TO
ADVANCE INTO THE NORTHWEST GULF AND STALL. PRIMARILY SEEING AN
OVER-RUNNING RAIN EVENT POTENTIALLY SETTING UP ACROSS THE AREA FOR
MID-WEEK AS OUR NEXT TROF/LOW ADVANCES ACROSS THE PLAINS. GFS
CONTINUES TO BE FASTER AND WEAKER WITH THIS FEATURE COMPARED TO
THE ECMWF. HOPEFULLY FINER DETAILS WILL BE SORTED OUT OVER THE
NEXT FEW DAYS.
MARINE...STRONG SOUTHERLY WINDS WILL CONTINUE TODAY ASSOCIATED WITH AN
AN AREA OF LOW PRESSURE OVER THE WESTERN GULF OF MEXICO. THE LOW
WILL PULL A COLD FRONT ACROSS THE COASTAL WATERS BY FRIDAY EVENING
..WITH A STRONG NORTHERLY FLOW DEVELOPING IN ITS WAKE.
&&
.PRELIMINARY POINT TEMPS/POPS...
KLCH 69 38 53 30 55 / 80 10 0 0 0
KBPT 68 36 51 31 54 / 80 10 0 0 0
KAEX 63 35 49 27 53 / 80 10 0 0 0
KLFT 72 41 52 30 55 / 80 20 0 0 0
&&
.LCH WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
TX...NONE.
GM...SMALL CRAFT ADVISORY UNTIL NOON CST SATURDAY FOR THE FOLLOWING
ZONES: COASTAL WATERS FROM CAMERON LA TO HIGH ISLAND TX OUT
20 NM...COASTAL WATERS FROM INTRACOASTAL CITY TO CAMERON LA
OUT 20 NM...COASTAL WATERS FROM LOWER ATCHAFALAYA RIVER TO
INTRACOASTAL CITY LA OUT 20 NM...WATERS FROM INTRACOASTAL
CITY TO CAMERON LA FROM 20 TO 60 NM...WATERS FROM CAMERON
LA TO HIGH ISLAND TX FROM 20 TO 60 NM...WATERS FROM LOWER
ATCHAFALAYA RIVER TO INTRACOASTAL CITY LA FROM 20 TO 60 NM.
SMALL CRAFT EXERCISE CAUTION UNTIL NOON CST TODAY FOR THE
FOLLOWING ZONES: VERMILION BAY.
&&
$$
AREA FORECAST DISCUSSION
NWS LAKE CHARLES LA
449 AM CST FRI DEC 28 2012
.DISCUSSION...SURFACE ANALYSIS SHOWING WARM FRONT GENERALLY JUST
INLAND OF COASTAL TEXAS AND SOUTHWEST LOUISIANA...ARCING JUST
OFFSHORE OF SOUTH CENTRAL LOUISIANA. ALONG AND NORTH OF
BOUNDARY. RADAR DEPICTING SCATTERED LIGHT TO MODERATE SHOWERS OVER
BOTH SOUTH TEXAS AND SOUTHWEST LOUISIANA. HAVE NOTED TEMPERATURES
GENERALLY RUNNING 20 TO 25 DEGREES ABOVE THAT OF 24 HOURS PRIOR.
LATEST VAD SHOWING A 40 KNOT LLJ ALREADY ESTABLISHED ABOVE LCH AT
850 MB TRANSPORTING IN VERY MOIST AND WARM AIR.
TODAY...WIDESPREAD SHOWERS AND A FEW THUNDERSTORMS ANTICIPATED AS
ASCENT IS ENHANCED WITH APPROACH OF PLAINS MID/UPPER LEVEL TROF.
LATEST RUC SUGGESTING SOUTH AND CENTRAL LOUISIANA WILL WARM SECTOR
AS A DEVELOPING TEXAS COAST SURFACE WAVE/WEAK LOW DEVELOPS...ADVANCING
INTO SOUTHWEST LOUISIANA BY LATE MORNING...AND EXITING NORTHEAST
BY LATE AFTERNOON WITH AN ACCOMPANYING COLD FRONT BEING DRUG WEST
TO EAST ACROSS THE AREA.
VERY IMPRESSIVE WIND FIELDS COMING TOGETHER AND GIVES PAUSE WHEN
INVESTIGATING. SOUTHERLY LLJ EXPECTED TO REMAIN OR STRENGTHEN
SLIGHTLY THROUGH THE REMAINDER OF THE MORNING WHILE MID LEVEL FLOW
VEERS TO SOUTHWEST AT 70-80 KTS...ENDING WITH A 120 WESTERLY JET ALOFT.
0-6 KM SHEAR VALUES PROGGED AT NEAR 70 KNOTS...WHILE LATEST RUC
COMING IN WITH PRE-FRONTAL HELICITY VALUES ABOVE 400 M2/S2. AT
THIS TIME SPC CARRYING AREA WITHIN A SEE TEXT NOTING A LACK OF
INSTABILITY. WOULD TAKE VERY LITTLE MORE TO SWING THE PENDULUM
TOWARD A SEVERE THREAT.
RAINS TAPER OFF WITH THE FRONTAL PASSAGE THIS AFTERNOON. WILL
MAINTAIN NO MORE THAN LOW END POPS INTO THIS EVENING OVER
ACADIANA.
WEEKEND...1030MB SURFACE HIGHS SETTLES INTO AREA WITH THE PASSAGE
OF THE FRONT WITH A DRY AND COOL WEATHER PATTERN SETTING UP. MAY
SEE OUR COOLEST MORNING THIS SEASON SUNDAY.
REMAINDER OF FORECAST...A SHALLOW COLD FRONT IS EXPECTED TO
ADVANCE INTO THE NORTHWEST GULF AND STALL. PRIMARILY SEEING AN
OVER-RUNNING RAIN EVENT POTENTIALLY SETTING UP ACROSS THE AREA FOR
MID-WEEK AS OUR NEXT TROF/LOW ADVANCES ACROSS THE PLAINS. GFS
CONTINUES TO BE FASTER AND WEAKER WITH THIS FEATURE COMPARED TO
THE ECMWF. HOPEFULLY FINER DETAILS WILL BE SORTED OUT OVER THE
NEXT FEW DAYS.
&&
.MARINE...STRONG SOUTHERLY WINDS WILL CONTINUE TODAY ASSOCIATED WITH AN
AN AREA OF LOW PRESSURE OVER THE WESTERN GULF OF MEXICO. THE LOW
WILL PULL A COLD FRONT ACROSS THE COASTAL WATERS BY FRIDAY EVENING
...WITH A STRONG NORTHERLY FLOW DEVELOPING IN ITS WAKE.
&&
.PRELIMINARY POINT TEMPS/POPS...
KLCH 69 38 53 30 55 / 80 10 0 0 0
KBPT 68 36 51 31 54 / 80 10 0 0 0
KAEX 63 35 49 27 53 / 80 10 0 0 0
KLFT 72 41 52 30 55 / 80 20 0 0 0
&&
.LCH WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
TX...NONE.
GM...SMALL CRAFT ADVISORY UNTIL NOON CST SATURDAY FOR THE FOLLOWING
ZONES: COASTAL WATERS FROM CAMERON LA TO HIGH ISLAND TX OUT
20 NM...COASTAL WATERS FROM INTRACOASTAL CITY TO CAMERON LA
OUT 20 NM...COASTAL WATERS FROM LOWER ATCHAFALAYA RIVER TO
INTRACOASTAL CITY LA OUT 20 NM...WATERS FROM INTRACOASTAL
CITY TO CAMERON LA FROM 20 TO 60 NM...WATERS FROM CAMERON
LA TO HIGH ISLAND TX FROM 20 TO 60 NM...WATERS FROM LOWER
ATCHAFALAYA RIVER TO INTRACOASTAL CITY LA FROM 20 TO 60 NM.
SMALL CRAFT EXERCISE CAUTION UNTIL NOON CST TODAY FOR THE
FOLLOWING ZONES: VERMILION BAY.
&&
$$
MARCOTTE
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
922 PM EST SAT DEC 29 2012
.UPDATE...
SOME FAIRLY LARGE BREAKS IN THE CLOUDS HAVE DEVELOPED THIS
EVENING...WHICH WILL REQUIRE A SLIGHT DOWNWARD ADJUSTMENT TO THE
OVERNIGHT MIN TEMP FORECAST. THE LOW LEVEL FLOW WILL TURN MORE
WESTERLY OVERNIGHT...WHICH WILL BRING SOME LAKE STRATUS AND
POSSIBLE FLURRIES BACK INTO SE MI. AN UPDATE WILL BE ISSUED TO
REFLECT THESE CHANGES. THE EXETER ONT RADAR SHOWS THAT THE SNOW
SHOWERS WHICH AFFECTED THE THUMB REGION EARLIER THIS EVENING ARE
NOW WELL OVER THE LAKE THANKS TO THE BACKING FLOW.
&&
.AVIATION...ISSUED 607 PM EST SAT DEC 29 2012
//DISCUSSION...
LIGHT SNOW WILL BE EXITING SOUTHEAST OF METRO DETROIT AROUND 00Z AS
SFC TROUGHING SLIDES OFF TO THE EAST AND DRIER AIR FUNNELS INTO THE
AREA FROM THE NORTHWEST. THERE HAVE BEEN SOME BREAKS IN THE LOW
STRATUS DEVELOPING OVER WEST-CENTRAL LOWER MI DUE TO SOME LOW LEVEL
DRYING. SOME OF THIS CLEARING MAY ADVANCE INTO THE SE MI TERMINALS
THIS EVENING. CONSIDERING THE POTENTIAL FOR SOME STRATUS
REDEVELOPMENT UNDER THE INVERSION TONIGHT...THE PROSPECTS FOR ANY
CLEARING CARRIES LOW CONFIDENCE AT THIS POINT. THE LOW LEVEL FLOW
WILL BACK TOWARD THE WEST OVERNIGHT...WHICH SHOULD ADVECT A
HEALTHY STRATUS DECK BACK INTO THE TERMINALS. THESE CLOUDS SHOULD
REMAIN PREVALENT INTO THE AFTERNOON. COLD AIR ADVECTION SHOULD
LIFT INVERSION HEIGHTS BY SUN MORNING...WHICH COULD PLACE CIGS
AROUND THE 3K FT THRESHOLD.
FOR DTW...RESIDUAL LIGHT SNOW/FLURRIES WILL END AROUND 00Z. THERE IS
A LOW CHANCE FOR SOME ADDITIONAL FLURRIES LATE TONIGHT AND SUN
MORNING AS A MORE DIRECT WESTERLY FLOW DEVELOPS OFF LAKE MI.
//DTW THRESHOLD THREATS...
* MEDIUM CONFIDENCE CEILINGS WILL BE BELOW 5000 FT TONIGHT AND
SUNDAY.
&&
.PREV DISCUSSION...ISSUED 406 PM EST SAT DEC 29 2012
SHORT TERM...THIS EVENING AND TONIGHT
SURFACE OBSERVATIONS UPSTREAM OVER NORTHERN LAKE HURON SUPPORT THE
MAIN STRUCTURE OF LAKE HURON AGGREGATE TROUGH HAS BROKEN DOWN. HIGH
RESOLUTION MODEL DATA HAS BEEN DEPICTING A SOLUTION THAT SUPPORTED
TRACKING A MESOVORTEX OR WELL ORGANIZED LOW LEVEL CONVERGENCE BANDING
STRUCTURE INTO PORTIONS OF HURON COUNTY AND THE NORTHERN THUMB AS
THE NORTHWESTERLY FLOW BECAME DOMINANT. WITH NO REDUCTION IN SFC
VISIBILITIES EARLIER THIS AFTERNOON FOR THE UPSTREAM SHORELINE AREAS
OF NORTHERN LOWER THIS IDEA FOR A MESOLOW CAN NOW BE ABANDONED. THIS
IS IMPORTANT BECAUSE THE IDEA OF LONGER DURATION DUE TO PROPAGATION
EFFECTS CAN BE APTLY BE DISCOUNTED AS WELL.
THE LAKE EFFECT EVENT NOW ANTICIPATED WILL BE A BRIEF
ONE...RELEGATED TO DEVELOPED ACTIVITY ADVECTING THROUGH ON THE LEAD
BACKED NORTHEASTERLY PUSH...VERY MUCH OF A SQUALL NATURE. SATELLITE
IMAGERY HAS SHOWN LOW CLOUD STRATOCUMULUS AGGRESSIVELY PUSHING INTO
EASTERN HURON COUNTY/MARKED WITH A GRAVITY STRUCTURE DURING THE PAST
HOUR. KDTX/KAPX BEAMS ARE BOTH OVERSHOOTING THE ACTIVITY WITH THE
AREAS OF INTEREST AT ROUGHLY 90 NM OR APPX 10 KFT AGL ON THE .5
DEGREE. ENVIRONMENT CANADA EXETER RADAR IS IN A BETTER LOCATION AND
IS SHOWING 25-30 DBZ EXTENDING INLAND/EAST OF BAD AXE. PLACED SOME
CALLS TO FIELD REPORTS AND DID MANAGE TO GET A CREDIBLE REPORT OF .5
INCH PER ONE HALF HOUR IN PORT HOPE. HOWEVER...THE SNOW HAD ALREADY
BEEN ON THE WANE SUGGESTING A TENUOUS SETUP. VARIOUS HI RESOLUTION
FLAVORS OF NWP - 3.5KM ARW WRF - 4 KM NMM SPC WRF - 3KM HRRR AND 13
KM RAP NOW AGREE IN SWEEPING THIS LAKE EFFECT THROUGH DURING 19-22Z.
DURATION OF SNOWFALL SHOULD ONLY LAST 1-1.5 HOUR AT MOST BEFORE
PUSHING BACK INTO LAKE HURON. THEREFORE...THE FORECAST WILL CALL FOR
A CONDITIONAL...UP TO 2 INCHES FOR LOCATIONS OF HURON/SANILAC
COUNTIES EAST OF A LINE FROM BAD AXE TO SANDUSKY.
OTHERWISE...LARGE SCALE MIDLEVEL TROUGH IS NOW ADVANCING INTO THE
WESTERN PORTIONS OF LOWER MICHIGAN. THE OLD 850-700MB DEFORMATION
FORCING THAT IS A CARRYOVER FROM LAST NIGHT HAS BEEN EFFICIENT IN
GENERATING AFTERNOON LIGHT SNOW/FLURRIES HERE ACROSS MUCH OF THE
REGION. HIGHEST REFLECTIVITIES HAVE BEEN IN EXCESS OF 20 DBZ BUT IS
LACKING IN ANY BITE/MORE OF A FUNCTION OF A FEW LARGE FLAKES. NOT
EXPECTING MUCH ACCUMULATION WITH THIS BEFORE DISSIPATING.
LOWS TONIGHT ARE VERY TRICKY AND DEPENDENT ON CLOUD COVER. DID STEER
THE FORECASTED LOWS A LITTLE TOWARDS RECENT GUIDANCE...AROUND 20
DEGREES.
LONG TERM...SUNDAY THROUGH SATURDAY
QUIET WEATHER EXPECTED SUNDAY/SUNDAY NIGHT AS HIGH PRESSURE BUILDS
ACROSS THE EASTERN CONUS W/ THE NORTHERN EXTENT OF SURFACE RIDGING
PROVIDING RELATIVELY LIGHT WINDS AND PARTLY CLOUDY SKIES FOR THE
SOUTHERN GREAT LAKES. AS THE RIDGE AXIS PROGRESSES EAST OF THE AREA
ON MONDAY...CLOUDS/WINDS WILL INCREASE WITH THE APPROACH OF THE NEXT
DISTURBANCE. THIS SYSTEM WILL CROSS NORTH OF THE AREA...BUT PUSH A
COLD FRONT THROUGH THE REGION BY MONDAY NIGHT.
THE STORM SYSTEM THAT HAS BASICALLY THE ONLY POTENTIAL TO BRING
NOTEWORTHY SNOW TO THE AREA IS CURRENTLY SPINNING OVER CALIFORNIA.
OF THE 12Z MODEL SUITE...THE NAM12 IS THE ONLY MODEL TRYING TO
MAINTAIN SOME INTEGRITY TO THIS WAVE AS IT EJECTS NORTHEAST OUT OF
THE FOUR CORNERS ALONG THE MEAN CENTRAL CONUS UPPER TROUGH INTO A
LARGELY CONFLUENT UPPER FLOW OVER THE NORTHEAST QUADRANT OF THE
NATION.
IN ADDITION TO SHOWING THE STRONGEST SOLUTION FOR THIS SHORTWAVE
ITSELF...THE OTHER MAIN DIFFERENCE IS THE HANDLING OF SHORTWAVE
ENERGY DIGGING SOUTH/SOUTHEAST INTO POLAR VORTEX NEAR HUDSON BAY AS
THE NAM..THROUGH THIS PROCESS...MAINTAINS A MORE NORTHERN POSITION
TO THIS FEATURE AND ALLOWS ITS "STRONGER" WAVE TO EJECT FURTHER
NORTH INTO THE OHIO VALLEY/SOUTHERN GREAT LAKES AND BRING SEVERAL
INCHES OF SNOW TO PARTS OF LOWER MICHIGAN.
WHILE THE ARCTIC JET ENERGY THAT WILL EVENTUALLY DICTATE THE
EVOLUTION OF THE HUDSON BAY LOW AND THE STEERING OF THE SOUTHERN
STREAM WAVE HAS YET TO BE SAMPLED VERY WELL...IT IS HARD TO IGNORE
SUCH A STRONG MODEL CONSENSUS AGAINST THE NAM...WHICH CALLS FOR
STRONGER AMPLIFICATION OF THE NORTHERN STREAM OVER EASTERN CANADA.
THIS SCENARIO WILL SHUNT THE SOUTHERN SYSTEM ON A TRACK WELL SOUTH
OF THE AREA AND KEEP ANY NOTABLE PRECIPITATION CONFINED TO THE
TENNESSEE VALLEY AND POINTS SOUTH WITH IT WITH JUST SCATTERED SNOW
SHOWERS OVER LOWER MICHIGAN WITHIN THE CYCLONIC NORTHWEST FLOW AS
COLDER AIR SURGES THROUGH THE GREAT LAKES WITH THE EVOLUTION OF THIS
NORTHERN SYSTEM.
WILL MAINTAIN A FORECAST BASED ON THIS IDEA...WITH LITTLE/NO CHANCE
OF SIGNIFICANT SNOW AND ALSO A DECENT COOL DOWN AS THIS STRONG
EASTERN CANADA UPPER LOW/TROUGH ALLOWS FOR A DECENT PENETRATION OF
POLAR/MODIFIED ARCTIC AIR INTO THE REGION. SO...AFTER EDGING BACK TO
HIGH TEMPERATURES IN THE 30S ON MONDAY...20S WILL BE THE RULE MUCH
OF THE UPCOMING WEEK WITH LOWS IN THE SINGLE DIGITS/TEENS MUCH OF
THE TIME.
MARINE...
A MODEST INCREASE TO THE SURFACE PRESSURE GRADIENT COMBINED WITH
WINDS ROTATING TO A MORE ONSHORE DIRECTION WILL MAINTAIN A MODERATE
BREEZE ACROSS CENTRAL AND SOUTHERN LAKE HURON TODAY. WAVE HEIGHTS
ARE ALREADY RAMPING UP INTO THE 4 TO 7 FOOT RANGE THIS AFTERNOON.
SMALL CRAFT ADVISORIES REMAIN IN EFFECT FROM OUTER SAGINAW BAY TO
PORT HURON THROUGH TONIGHT.
A MODERATE SOUTHWEST FLOW WILL DEVELOP SUNDAY NIGHT INTO MONDAY AS
THE SURFACE PRESSURE GRADIENT TIGHTENS OVER AREA WATERS AS LOW
PRESSURE CROSSES NORTH OF THE REGION. GUSTY NORTHWEST WINDS WILL
DEVELOP BY MIDWEEK NEXT WEEK AS COLDER AIR SPREADS INTO THE GREAT
LAKES REGION IN THE WAKE OF THIS SYSTEM.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...
SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT
SANILAC...UNTIL 7 AM SUNDAY.
SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT SANILAC TO PORT
HURON...UNTIL 10 AM SUNDAY.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
UPDATE.......SC
AVIATION.....SC
SHORT TERM...CB
LONG TERM....DG
MARINE.......CB
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
646 PM EST SAT DEC 29 2012
.SYNOPSIS...
ISSUED AT 321 PM EST SAT DEC 29 2012
ANOTHER ROUND OF MOSTLY LIGHT SNOW WILL OCCUR OVERNIGHT. UP TO AN
INCH OR TWO OF ACCUMULATION WILL BE POSSIBLE ALONG THE LAKESHORE
NEAR SOUTH HAVEN. AFTER A RATHER DRY SUNDAY AND SUNDAY NIGHT...THE
COMING WORK WEEK WILL BE COLDER THAN NORMAL WITH SLIGHT CHANCES FOR
SNOW MAINLY NEAR THE LAKE SHORE EACH DAY.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 321 PM EST SAT DEC 29 2012
AS NOTED IN THE PREVIOUS FORECAST UPDATE DISCUSSION...WE EXPECT
A SHOT OF LAKE ENHANCED SNOW EARLY TONIGHT MAINLY SOUTH OF HOLLAND.
THE BEST TIMEFRAME LOOKS BETWEEN 10 PM AND 2 AM. MOST RECENT RUNS
OF THE RAP HAVE BACKED TOTAL ACCUMULATIONS AT SOUTH HAVEN DOWN TO AN
INCH OR LESS COMPARED TO EARLIER AMOUNTS OF 2+ INCHES. HOWEVER...
PREFER TO MATCH UP WITH SLIGHTLY HIGHER AMOUNTS ADVERTISED BY IWX TO
ACCOUNT FOR LAKE MOISTURE THAT MAY NOT BE HANDLED WELL BY THE MODELS.
OTHERWISE...FEW CHANGES WERE MADE TO THE FORECAST. DID RAISE POPS
AND SNOW AMOUNTS MONDAY AND MONDAY NIGHT OVER OUR NRN ZONES TO
ACCOUNT FOR COLD FRONT DROPPING SOUTH THROUGH THE AREA AND TO BETTER
MATCH WITH APX TO OUR NORTH.
.LONG TERM...(TUESDAY THROUGH SATURDAY)
ISSUED AT 321 PM EST SAT DEC 29 2012
THE FOCUS OF THE FORECAST CONTINUES TO BE CENTERED ON THE ARCTIC AIR
MASS THAT IS EXPECTED TO COME DOWN AND THE RESULTING LAKE EFFECT
SNOW SHOWER CHCS.
TUE AND TUE NIGHT LOOK RATHER QUIET. SOME LIGHT LAKE EFFECT WILL BE
POSSIBLE ON TUE AS WE SHOULD SEE A WEAK UPPER TROUGH MOVE BY.
SUFFICIENT INSTABILITY OVER THE LAKE WILL ALSO BE PRESENT WITH H850
TEMPS AROUND -10 TO -12C. THE LAKE EFFECT POTENTIAL WILL DIMINISH
LATE TUE AND MAINLY DRY CONDITIONS ARE EXPECTED TUE NIGHT WITH
RIDGING BUILDING IN.
WE ARE STILL EXPECTING A FAIRLY VIGOROUS UPPER TROUGH TO DROP DOWN
IN THE REGION WED-THU. THIS WILL BRING A THREAT OF SYNOPTIC SNOW
ALONG WITH SOME LAKE ENHANCEMENT/POTENTIAL AS COLDER AIR WILL FOLLOW
IN BEHIND IT. THE MODELS HAVE BEEN STRUGGLING WITH THE EXACT TRACK
WHICH WILL HAVE IMPLICATIONS ON HOW MUCH SNOW FALLS AND WHERE IT
FALLS. THE LATEST MODELS SHOW IT TRACKING NORTH OF THE AREA AND
HAVING MOST OF THE SNOW NORTH OF IT. THE FLOW IS ALSO IMPORTANT DUE
TO LAKE ENHANCEMENT POTENTIAL. FOR NOW WE HAVE A CHC OF SNOW SHOWERS
EVERYWHERE. THIS WILL HAVE TO BE FINE TUNED.
THE NOTEWORTHY CHANGE IN THE MODELS IS A TREND TOWARD A SHORTER STAY
FOR THE ARCTIC AIR. THE MODELS ARE MORE PROGRESSIVE THAN PREVIOUS
RUNS WITH THE UPPER TROUGH AND ARCTIC AIR. THIS IS LIKELY HAVING TO
DO WITH THE SPLIT FLOW THAT DEVELOPS. THE UPPER TROUGH IS EXPECTED
TO BE GONE BY THU NIGHT. THIS WOULD MEAN LESS LAKE EFFECT POTENTIAL.
BY FRI...THE AIR AT H850 IS NOT EVEN COLD ENOUGH FOR LAKE EFFECT. WE
END UP ONCE AGAIN IN NO MANS LAND BETWEEN THE JET STREAMS. THIS
WOULD BRING US SEASONABLE TEMPERATURES WITH LITTLE IF ANY PCPN CHCS.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 646 PM EST SAT DEC 29 2012
VFR CONDITIONS ARE DEVELOPING IN THE WAKE OF SNOW THAT IS MOVING
SOUTH OUT OF THE AREA. THIS WILL BE TEMPORARY THOUGH AS NORTHWEST
FLOW WILL BRING MVFR CEILINGS BACK IN FROM WEST TO EAST THROUGH
THE TAF SITES FROM 01Z TO 06Z OR SO. THE SWITCH IN WIND DIRECTION
WILL ALSO BRING IN SOME SNOW SHOWERS...WITH KMKG AND KAZO THE
SITES MOST LIKELY TO BE AFFECTED. COULD SEE SOME MVFR VSBY/S AS
THE SNOW SHOWERS MOVE THROUGH.
THE SNOW SHOWER ACTIVITY SHOULD COME TO AN END BETWEEN 07Z AND 10Z
ALTHOUGH THE MVFR CEILINGS WILL REMAIN INTO SUNDAY MORNING. IT
WON/T BE UNTIL ABOUT 18Z OR SO WHEN THE CEILINGS LIFT INTO A VFR
DECK OR SCATTER OUT. IMPROVING CONDITIONS WILL BE THE BOTTOM LINE
FOR SUNDAY AFTER SOME SNOW SHOWER ACTIVITY AND MVFR CEILINGS TONIGHT.
&&
.MARINE...
ISSUED AT 351 PM EST SAT DEC 29 2012
NO CHANGES WERE MADE TO THE INHERITED FORECAST. LATEST LOCAL RUN
OF THE GLERL KEEPS WAVES BELOW SMALL CRAFT CRITERIA UNTIL WELL
AFTER MIDNIGHT. THIS IS A FEW HOURS AFTER THE 10 PM OFFICIAL START
OF THE SMALL CRAFT ADVISORY. THERE MAY BE A BRIEF PERIOD OF SUB-
ADVISORY WAVES SUNDAY AFTERNOON. HOWEVER THIS WILL BE SHORT-LIVED
AS WINDS NEAR OR AT GALE FORCE ARE EXPECTED BOTH SUNDAY NIGHT AND
MONDAY.
&&
.HYDROLOGY...
ISSUED AT 321 PM EST SAT DEC 29 2012
NO HYDRO CONCERNS DUE TO VERY LITTLE QPF. RIVER ICE WILL BE LIKELY
TO DEVELOP BY THE END OF THE COMING WORK WEEK.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 1 PM EST SUNDAY
FOR LMZ844>849.
&&
$$
SYNOPSIS...TJT
SHORT TERM...TJT
LONG TERM...NJJ
AVIATION...DUKE
HYDROLOGY...TJT
MARINE...TJT
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
607 PM EST SAT DEC 29 2012
.AVIATION...
//DISCUSSION...
LIGHT SNOW WILL BE EXITING SOUTHEAST OF METRO DETROIT AROUND 00Z AS
SFC TROUGHING SLIDES OFF TO THE EAST AND DRIER AIR FUNNELS INTO THE
AREA FROM THE NORTHWEST. THERE HAVE BEEN SOME BREAKS IN THE LOW
STRATUS DEVELOPING OVER WEST-CENTRAL LOWER MI DUE TO SOME LOW LEVEL
DRYING. SOME OF THIS CLEARING MAY ADVANCE INTO THE SE MI TERMINALS
THIS EVENING. CONSIDERING THE POTENTIAL FOR SOME STRATUS
REDEVELOPMENT UNDER THE INVERSION TONIGHT...THE PROSPECTS FOR ANY
CLEARING CARRIES LOW CONFIDENCE AT THIS POINT. THE LOW LEVEL FLOW
WILL BACK TOWARD THE WEST OVERNIGHT...WHICH SHOULD ADVECT A
HEALTHY STRATUS DECK BACK INTO THE TERMINALS. THESE CLOUDS SHOULD
REMAIN PREVALENT INTO THE AFTERNOON. COLD AIR ADVECTION SHOULD
LIFT INVERSION HEIGHTS BY SUN MORNING...WHICH COULD PLACE CIGS
AROUND THE 3K FT THRESHOLD.
FOR DTW...RESIDUAL LIGHT SNOW/FLURRIES WILL END AROUND 00Z. THERE IS
A LOW CHANCE FOR SOME ADDITIONAL FLURRIES LATE TONIGHT AND SUN
MORNING AS A MORE DIRECT WESTERLY FLOW DEVELOPS OFF LAKE MI.
//DTW THRESHOLD THREATS...
* MEDIUM CONFIDENCE CEILINGS WILL BE BELOW 5000 FT TONIGHT AND
SUNDAY.
&&
.PREV DISCUSSION...ISSUED 406 PM EST SAT DEC 29 2012
SHORT TERM...THIS EVENING AND TONIGHT
SURFACE OBSERVATIONS UPSTREAM OVER NORTHERN LAKE HURON SUPPORT THE
MAIN STRUCTURE OF LAKE HURON AGGREGATE TROUGH HAS BROKEN DOWN. HIGH
RESOLUTION MODEL DATA HAS BEEN DEPICTING A SOLUTION THAT SUPPORTED
TRACKING A MESOVORTEX OR WELL ORGANIZED LOW LEVEL CONVERGENCE BANDING
STRUCTURE INTO PORTIONS OF HURON COUNTY AND THE NORTHERN THUMB AS
THE NORTHWESTERLY FLOW BECAME DOMINANT. WITH NO REDUCTION IN SFC
VISIBILITIES EARLIER THIS AFTERNOON FOR THE UPSTREAM SHORELINE AREAS
OF NORTHERN LOWER THIS IDEA FOR A MESOLOW CAN NOW BE ABANDONED. THIS
IS IMPORTANT BECAUSE THE IDEA OF LONGER DURATION DUE TO PROPAGATION
EFFECTS CAN BE APTLY BE DISCOUNTED AS WELL.
THE LAKE EFFECT EVENT NOW ANTICIPATED WILL BE A BRIEF
ONE...RELEGATED TO DEVELOPED ACTIVITY ADVECTING THROUGH ON THE LEAD
BACKED NORTHEASTERLY PUSH...VERY MUCH OF A SQUALL NATURE. SATELLITE
IMAGERY HAS SHOWN LOW CLOUD STRATOCUMULUS AGGRESSIVELY PUSHING INTO
EASTERN HURON COUNTY/MARKED WITH A GRAVITY STRUCTURE DURING THE PAST
HOUR. KDTX/KAPX BEAMS ARE BOTH OVERSHOOTING THE ACTIVITY WITH THE
AREAS OF INTEREST AT ROUGHLY 90 NM OR APPX 10 KFT AGL ON THE .5
DEGREE. ENVIRONMENT CANADA EXETER RADAR IS IN A BETTER LOCATION AND
IS SHOWING 25-30 DBZ EXTENDING INLAND/EAST OF BAD AXE. PLACED SOME
CALLS TO FIELD REPORTS AND DID MANAGE TO GET A CREDIBLE REPORT OF .5
INCH PER ONE HALF HOUR IN PORT HOPE. HOWEVER...THE SNOW HAD ALREADY
BEEN ON THE WANE SUGGESTING A TENUOUS SETUP. VARIOUS HI RESOLUTION
FLAVORS OF NWP - 3.5KM ARW WRF - 4 KM NMM SPC WRF - 3KM HRRR AND 13
KM RAP NOW AGREE IN SWEEPING THIS LAKE EFFECT THROUGH DURING 19-22Z.
DURATION OF SNOWFALL SHOULD ONLY LAST 1-1.5 HOUR AT MOST BEFORE
PUSHING BACK INTO LAKE HURON. THEREFORE...THE FORECAST WILL CALL FOR
A CONDITIONAL...UP TO 2 INCHES FOR LOCATIONS OF HURON/SANILAC
COUNTIES EAST OF A LINE FROM BAD AXE TO SANDUSKY.
OTHERWISE...LARGE SCALE MIDLEVEL TROUGH IS NOW ADVANCING INTO THE
WESTERN PORTIONS OF LOWER MICHIGAN. THE OLD 850-700MB DEFORMATION
FORCING THAT IS A CARRYOVER FROM LAST NIGHT HAS BEEN EFFICIENT IN
GENERATING AFTERNOON LIGHT SNOW/FLURRIES HERE ACROSS MUCH OF THE
REGION. HIGHEST REFLECTIVITIES HAVE BEEN IN EXCESS OF 20 DBZ BUT IS
LACKING IN ANY BITE/MORE OF A FUNCTION OF A FEW LARGE FLAKES. NOT
EXPECTING MUCH ACCUMULATION WITH THIS BEFORE DISSIPATING.
LOWS TONIGHT ARE VERY TRICKY AND DEPENDENT ON CLOUD COVER. DID STEER
THE FORECASTED LOWS A LITTLE TOWARDS RECENT GUIDANCE...AROUND 20
DEGREES.
LONG TERM...SUNDAY THROUGH SATURDAY
QUIET WEATHER EXPECTED SUNDAY/SUNDAY NIGHT AS HIGH PRESSURE BUILDS
ACROSS THE EASTERN CONUS W/ THE NORTHERN EXTENT OF SURFACE RIDGING
PROVIDING RELATIVELY LIGHT WINDS AND PARTLY CLOUDY SKIES FOR THE
SOUTHERN GREAT LAKES. AS THE RIDGE AXIS PROGRESSES EAST OF THE AREA
ON MONDAY...CLOUDS/WINDS WILL INCREASE WITH THE APPROACH OF THE NEXT
DISTURBANCE. THIS SYSTEM WILL CROSS NORTH OF THE AREA...BUT PUSH A
COLD FRONT THROUGH THE REGION BY MONDAY NIGHT.
THE STORM SYSTEM THAT HAS BASICALLY THE ONLY POTENTIAL TO BRING
NOTEWORTHY SNOW TO THE AREA IS CURRENTLY SPINNING OVER CALIFORNIA.
OF THE 12Z MODEL SUITE...THE NAM12 IS THE ONLY MODEL TRYING TO
MAINTAIN SOME INTEGRITY TO THIS WAVE AS IT EJECTS NORTHEAST OUT OF
THE FOUR CORNERS ALONG THE MEAN CENTRAL CONUS UPPER TROUGH INTO A
LARGELY CONFLUENT UPPER FLOW OVER THE NORTHEAST QUADRANT OF THE
NATION.
IN ADDITION TO SHOWING THE STRONGEST SOLUTION FOR THIS SHORTWAVE
ITSELF...THE OTHER MAIN DIFFERENCE IS THE HANDLING OF SHORTWAVE
ENERGY DIGGING SOUTH/SOUTHEAST INTO POLAR VORTEX NEAR HUDSON BAY AS
THE NAM..THROUGH THIS PROCESS...MAINTAINS A MORE NORTHERN POSITION
TO THIS FEATURE AND ALLOWS ITS "STRONGER" WAVE TO EJECT FURTHER
NORTH INTO THE OHIO VALLEY/SOUTHERN GREAT LAKES AND BRING SEVERAL
INCHES OF SNOW TO PARTS OF LOWER MICHIGAN.
WHILE THE ARCTIC JET ENERGY THAT WILL EVENTUALLY DICTATE THE
EVOLUTION OF THE HUDSON BAY LOW AND THE STEERING OF THE SOUTHERN
STREAM WAVE HAS YET TO BE SAMPLED VERY WELL...IT IS HARD TO IGNORE
SUCH A STRONG MODEL CONSENSUS AGAINST THE NAM...WHICH CALLS FOR
STRONGER AMPLIFICATION OF THE NORTHERN STREAM OVER EASTERN CANADA.
THIS SCENARIO WILL SHUNT THE SOUTHERN SYSTEM ON A TRACK WELL SOUTH
OF THE AREA AND KEEP ANY NOTABLE PRECIPITATION CONFINED TO THE
TENNESSEE VALLEY AND POINTS SOUTH WITH IT WITH JUST SCATTERED SNOW
SHOWERS OVER LOWER MICHIGAN WITHIN THE CYCLONIC NORTHWEST FLOW AS
COLDER AIR SURGES THROUGH THE GREAT LAKES WITH THE EVOLUTION OF THIS
NORTHERN SYSTEM.
WILL MAINTAIN A FORECAST BASED ON THIS IDEA...WITH LITTLE/NO CHANCE
OF SIGNIFICANT SNOW AND ALSO A DECENT COOL DOWN AS THIS STRONG
EASTERN CANADA UPPER LOW/TROUGH ALLOWS FOR A DECENT PENETRATION OF
POLAR/MODIFIED ARCTIC AIR INTO THE REGION. SO...AFTER EDGING BACK TO
HIGH TEMPERATURES IN THE 30S ON MONDAY...20S WILL BE THE RULE MUCH
OF THE UPCOMING WEEK WITH LOWS IN THE SINGLE DIGITS/TEENS MUCH OF
THE TIME.
MARINE...
A MODEST INCREASE TO THE SURFACE PRESSURE GRADIENT COMBINED WITH
WINDS ROTATING TO A MORE ONSHORE DIRECTION WILL MAINTAIN A MODERATE
BREEZE ACROSS CENTRAL AND SOUTHERN LAKE HURON TODAY. WAVE HEIGHTS
ARE ALREADY RAMPING UP INTO THE 4 TO 7 FOOT RANGE THIS AFTERNOON.
SMALL CRAFT ADVISORIES REMAIN IN EFFECT FROM OUTER SAGINAW BAY TO
PORT HURON THROUGH TONIGHT.
A MODERATE SOUTHWEST FLOW WILL DEVELOP SUNDAY NIGHT INTO MONDAY AS
THE SURFACE PRESSURE GRADIENT TIGHTENS OVER AREA WATERS AS LOW
PRESSURE CROSSES NORTH OF THE REGION. GUSTY NORTHWEST WINDS WILL
DEVELOP BY MIDWEEK NEXT WEEK AS COLDER AIR SPREADS INTO THE GREAT
LAKES REGION IN THE WAKE OF THIS SYSTEM.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...
SMALL CRAFT ADVISORY...OUTER SAGINAW BAY...UNTIL 1 AM SUNDAY.
SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT
SANILAC...UNTIL 7 AM SUNDAY.
SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT SANILAC TO PORT
HURON...FROM 10 PM SATURDAY TO 10 AM SUNDAY.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
AVIATION.....SC
SHORT TERM...CB
LONG TERM....DG
MARINE.......CB
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
612 PM CST SAT DEC 29 2012
.UPDATE...
UPDATED FOR AVIATION DISCUSSION BELOW.
&&
.DISCUSSION...
/ISSUED 406 PM CST SAT DEC 29 2012/
OVERVIEW...MOSTLY CLEAR AND COLD TONIGHT WITH CONTINUING COLD
TEMPERATURES THROUGH THE NEW YEAR. THE NEXT CHANCE FOR LIGHT
PRECIP ARRIVES SUNDAY NIGHT INTO MONDAY MORNING WITH A SMALL
CHANCE FOR LIGHT FREEZING DRIZZLE IN SOUTHEAST MN AND PORTIONS OF
WESTERN WI. THE NEXT CHANCE FOR LIGHT SNOW WILL BE WEDNESDAY INTO
THURSDAY. ALTHOUGH...THERE IS STILL A LOT OF UNCERTAINTY WITH THIS
SYSTEM AND IT DOESN`T LOOK PARTICULARLY STRONG AT THIS TIME. NEW
YEARS EVE LOOKS LIKE THE COLDEST NIGHT OF THE WINTER SEASON SO FAR
IN MANY LOCATIONS.
FLOW BECOMES ANTICYCLONIC TONIGHT AS TROUGH SUPPLYING ALL THE SNOW
TO THE EAST COAST CONTINUES ITS EASTWARD TRACK. TROUGH DROPPING
SOUTH OUT OF THE INTERIOR OF CANADA MOVES ACROSS LAKE WINNIPEG BY
THIS TIME TOMORROW. LIGHT SNOW LOOKS POSSIBLE IN FAR NORTHERN
MN TOMORROW...BUT EVEN WITH A COUPLE MORE SUBTLE SHORTWAVES
TRAILING THIS FEATURE AND A SLIGHT SURFACE REFLECTION/COLD
FRONT...MOST OF MN/WI WILL REMAIN DRY. THERE ISN`T MUCH
FORCING/FGEN...BUT THERE IS LOW LEVEL WARM AIR ADVECTION AND A
MODEST AMOUNT OF MOISTURE TRANSPORT TOMORROW NIGHT. WE WARM TEMPS
TOMORROW TO REFLECT OUR THINKING OF MOSTLY CLEAR SKIES AND
SOUTHWEST FLOW. THE GFS/NAM SUGGEST SATURATION FROM ABOUT 900-925
MB TO THE SFC. CHECKING OUT THE ISENTROPIC SURFACES...A DECENT
AMOUNT OF UPGLIDE ON THE 270-280 ISENTROPIC SURFACES...WHICH WOULD
BE IN THE SATURATION. SOUNDINGS STAY MOSTLY ABOVE -10 C...KEEPING
ICE OUT OF THE CLOUD...AND MAKING FREEZING DRIZZLE THE MORE
PROBABLE PREIP TYPE. WE ADDED PATCHY FREEZING DRIZZLE TO THE
FORECAST...BUT LEFT POPS BELOW 15% AT THIS TIME. BETTER SATURATION
LOOKS TO OCCUR IN SOUTHEAST MN AND PORTIONS OF SOUTHWEST/WEST
CENTRAL WI.
AFTER SUNDAY NIGHT...MUCH OF THE COUNTRY WILL SEE A STEADY SUPPLY
OF DRY CONTINENTAL AIR...WITH TRUE ARCTIC AIR INTRUDING INTO THE
NORTHERN PLAINS AND UPPER MISSISSIPPI RIVER VALLEY EARLY THIS
WEEK. THE MODEL GUIDANCE IS STILL QUITE VARIED IN FORECAST LOWS
NEW YEARS EVE. THE GEM/EC/NAM SUGGEST QUITE A FEW LOCATIONS WILL BE
-10 TO -20 BELOW BY TUESDAY MORNING. THE EARLY MORNING FORECAST
/PREVIOUSLY ISSUED/ DID A GOOD JOB DRIVING TEMPS DOWN BEHIND THE
ARCTIC BOUNDARY. SO...REALLY DIDN`T CHANGE TEMPS A WHOLE LOT FROM
WHAT WAS PREVIOUSLY FORECASTED.
ALL BUT THE GEM NOW FORECAST MOST OF THE LIGHT SNOW ACROSS
CENTRAL/NORTHERN MN AND NORTHERN WI WEDNESDAY NIGHT AND
THURSDAY...OR NOT AT ALL /GFS/. THE 29.12Z EC HAS TRENDED TOWARD A
DEEPER SURFACE LOW BUT ALSO SHIFTED ABOUT A HALF STATE TO THE NORTH.
THIS IS A CLIPPER SYSTEM WITH LIGHT QPF AND HIGH SNOW RATIOS...BUT
THERE IS STILL TOO MUCH UNCERTAINTY TO INCLUDE MUCH HIGHER THAN
SLIGHT CHANCE POPS AT THIS POINT.
&&
.AVIATION.../00Z TAF ISSUANCE/
LAST BATCH OF MVFR CEILINGS NOW MOVING EASTWARD THROUGH EASTERN MN
AND WISC...AND WAS JUST CLEARING KMSP AT 00Z. LATEST RAP AND
SATELLITE TRENDS SUGGEST IT SHOULD EXIT KEAU AROUND 03Z. BELIEVE
SKY SHOULD BE MOSTLY CLEAR WITH VSBY ABOVE 5SM THROUGH THE NIGHT. TEMP
DEWPOINT DEPRESSIONS ARE SEVERAL DEGREES AT 23Z AND THINK THE
DEPRESSION WILL REMAIN A DEGREE OR TWO OVERNIGHT BUT CONFIDENCE
IS ONLY AVERAGE. LAST NIGHTS FOG IN ERN SD WAS IN THE RIDGE AXIS
WHICH IS SHIFTING EAST TONIGHT. WESTERN WISC IS THE AREA TO WATCH
FOR MORE FOG/STRATUS WHERE AXIS MAY STILL BE OVER THERE AT 09Z.
SUNDAY SHOULD BE QUIET. INCOMING FRONT LOOKS TO REACH KAXN LATE
SUNDAY AFTERNOON WITH MVFR STRATUS...THEN PROGRESS SOUTHEAST AFTER
00Z MONDAY.
KMSP...SMALL POTENTIAL FOR MVFR CEILING/VSBY TO REDEVELOP AFTER
06Z SUNDAY. IF THAT HAPPENS...CEILINGS WOULD PROBABLY BE AROUND
1200-1500 FT AGL ALONG WITH VSBY AROUND 5SM. NOT ENOUGH POTENTIAL
TO HAVE IT IN THE TAFS AT THIS POINT. SUNDAY WILL FEATURE LIGHT
SOUTHERLY WINDS WITH NEXT ARCTIC FRONT ARRIVING AROUND 03Z MONDAY
WITH SOME MVFR CEILINGS AROUND 2000 FT AGL.
/OUTLOOK FOR KMSP/
MON...VFR. WINDS NW 10-15 KTS.
TUE...VFR. WINDS SW 5-10 KTS.
WED...VFR. SLIGHT CHANCE OF MVFR AND LIGHT SNOW. WINDS NW 5-10
KTS.
&&
MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
CLF/TDK
AREA FORECAST DISCUSSION...UPDATED
NWS ST LOUIS MO
1206 PM CST FRI DEC 28 2012
.UPDATE...
ISSUED AT 1205 PM CST FRI DEC 28 2012
LATEST DATA INDICATE SHORTWAVE LIFTING NE OUT OF ARKANSAS WILL
BRING A BIT MORE PRECIP IN THE FORM OF SNOW TO SE PARTS OF THE
CWA THAN EARLIER EXPECTED...AND REGIONAL RADAR TRENDS SEEM TO BE
SUPPORTING THIS NWD SHIFT IN THE N EDGE OF THE PRECIP SHIELD. ALL
12Z GUIANCE SUGGESTS MEASUREABLE SNOW IN OUR FAR SE COUNTIES WITH
SNOWFALLS IN THE 1-3 INCH RANGE. MODELS ARE A BIT LESS CERTAIN WRT
N EDGE OF THE SNOWFALL...AND ATTM HAVE USED THE HRRR TO DELINEATE
THE N EDGE OF THE SNOWFALL...ESSENTIALLY...AND ONCE AGAIN...OVER S
SECTIONS OF THE ST LOUIS METRO AREA. HAVE POSTED A WINTER WEATHER
ADVISORY FOR THIS AFTERNOON AND EVENING FOR OUR EXTREME SOUTHEAST
COUNTIES...AND WILL MONITOR TRENDS DURING THE AFTERNOON TO SEE IF
THIS NEEDS TO BE EXPANDED N FOR THE EVENING RUSH HOUR.
TRUETT
&&
.SHORT TERM...
ISSUED AT 353 AM CST FRI DEC 28 2012
.SYNOPSIS...
TWO WEATHER SYSTEMS WILL IMPACT THE REGION OVER THE NEXT WEEK. ONE
TODAY AND THE OTHER EARLY NEXT WEEK. THE AREA IS UNDER THE INFLUENCE
OF SW FLOW ALOFT THIS MORNING ON THE FRONT SIDE OF A LONGWAVE
TROUGH AND A COUPLE OF SHORT WAVES. WATER VAPOR IMAGERY SHOWS A
TIGHT CIRCULATION ACROSS SE ND AND NE NEB THIS MORNING. THIS FEATURE
WAS RESPONSIBLE FOR A 2-6 INCH SWATH OF SNOW ACROSS THAT AREA OVER
THE PAST 24 HRS. AT THE SURFACE...WEAK LOW PRESSURE ALONG THE KS/MO
BORDER IS AT THE TOP OF AN INVERTED TROF EXTENDING FROM A STRONGER
AREA OF LOW PRESSURE ALONG THE SE COAST OF TX.
.SHORT TERM (TODAY THRU SUNDAY NIGHT)...
THE WX SCENARIO OVER THE NEXT 24 HRS HAS PROVIDED A TRICKY
FCST...ESP WRT TO P-TYPE. ALOFT...THE H500 LOW OVER THE PLAINS WILL
BECOME ABSORBED INTO THE LEAD SHORT WAVE TODAY. A BAND OF LIGHT SNOW
WILL CONTINUE TO BE ASSOC WITH THIS FEATURE WELL TO THE OF THE CWA.
THE WEAK SFC LOW ALONG THE KS/MO BORDER WILL PROGRESS TO CNTRL IL BY
THIS EVENING WHILE THE STRONGER LOW MOVES TO STHRN/CNTRL MS BY 00Z.
THE INVERTED TROF STRUCTURE REMAINS INTACT THRU THE PERIOD. THERE
ARE SEVERAL QUESTIONS WRT TO PRECIP AMOUNT AND TYPE ACROSS THE CWA
TODAY.
FIRST...WHAT ARE THE CHANCES FOR FZDZ TODAY? THE AREA REMAINS UNDER
WEAK FORCING THRU THE PERIOD. UPPER FORCING WAINS THRU THE MORNING
AS MID/HIGH LEVEL MOISTURE MOVES EAST AS WELL. WHAT REMAINS IS A
SHALLOW SATURATED LAYER NEAR THE SFC THAT IS MAINLY ABOVE -10C THRU
THE LAYER. THIS PRECLUDES ICE CRYSTALS SO WE ARE LEFT WITH DRIZZLE
OR FREEZING DRIZZLE DEPENDING ON SFC TEMPS. THE AMOUNT OF PRECIP IS
ALSO ANOTHER CONCERN AS IT OBVIOUSLY DOESN/T TAKE MUCH -FZDZ TO
CAUSE ISSUES. AFTER THE UPPER LEVEL FORCING MOVES EAST THIS
MORNING...WEAK LOW LEVEL FORCING REMAINS IN ASSOC WITH THE
APPROACHING SHORT WAVE. THE CONCERN IS IF THIS WILL BE ENOUGH LIFT
TO GENERATE MEASURABLE PRECIP. DUE TO THE WEAK NATURE OF THE LIFT I
HAVE DOUBTS THAT THIS WILL BE THE CASE. SO...I DROPPED MENTIONABLE
POPS ACROSS THE CWA AND WENT WITH A TRACE EVENT WITH AREAS OF
FZDZ/DZ. NON-MEASURABLE DOESN/T NECESSARILY MEAN NOT IMPORTANT AS
WE HAVE SEEN IN THE PAST...IT DOESN/T TAKE MUCH FZDZ TO CAUSE
PROBLEMS ON THE ROADS. GROUND TEMPS ARE AT OR JUST ABOVE FREEZING SO
I THINK THE BIGGEST THREAT FROM FZDZ WILL BE ELEVATED SFCS INCLUDING
BRIDGES AND OVERPASSES. WITH ANY LUCK...THE MAJORITY OF THE DRIZZLE
WILL HOLD OFF UNTIL AFTER THE MORNING RUSH AND TEMPS GET ABOVE
FREEZING.
THE NEXT CONCERN IS PRECIP CHANCES ACROSS THE SE CWA. 00Z
MODELS RUNS HAVE THE QPF GRADIENT ALONG THE CWA WITH PAH. MODELS
CONSENSUS IS THAT OUR SERN COUNTIES WILL SEE MEASURABLE PRECIP
STARTING LATER THIS AFTN AND CONTINUING INTO THIS EVENING. MODEL
GUIDANCE INDICATES DECENT LIFT FROM OMEGA AND FRONTOGENETICAL
CIRCULATIONS ALONG THE BORDER AS WELL. THIS WILL BE A CLOSE CALL AS
THE QPF GRADIENT WILL LIKELY BE FAIRLY TIGHT. IT/S CERTAINLY
POSSIBLE THAT ALL/MOST OF THE PRECIP COULD REMAIN IN PAH/S CWA AND
OUR AREA RECEIVES LITTLE TO NO PRECIP. ON THE OTHER HAND...A SLIGHT
SHIFT NORTH AND OUR AREA COULD RECEIVE AT LEAST A TENTH OF AN INCH.
THIS IN ITSELF IS NOT A BIG DEAL UNTIL TEMP PROFILES ARE EXAMINED.
SOME MODELS INDICATE MOST IF NOT ALL OF THIS MAY FALL IN THE FORM OF
SNOW. THE NAM IS A WARM OUTLIER AND WAS NOT USED IN THE TEMPS FCST
TODAY OR TONIGHT. THE HEAVILY NAM INFLUENCED SREF WAS ALSO WARM.
SURPRISINGLY THE LOCAL WRF WAS SIGNIFICANTLY COOLER THAN THE NAM.
THE LOCAL WRF...GFS...ECMWF AND GEM ALL HAD SFC WET BULB AND TEMPS
IN THE 30-35 DEGREE RANGE WITH CRITICAL THICKNESSES VERY CLOSE AS
WELL. THE EVENT SHOULD START AS RAIN OR A RAIN/SNOW MIX AND THEN
TRANSITION TO ALL SNOW AS THE EVENING PROGRESSES WITH SFC TEMPS
COOLING AND COLDER AIR ALOFT CONTINUING TO FILTER IN. HAVE BUMPED
POPS UP ACROSS THE SERN ZONES AND ADDED IN LESS THAN AN INCH OF
SNOW. THIS WILL HAVE TO BE FINE TUNED THRU THE DAY.
LASTLY...THERE IS A SMALL CHANCE AT MEASURABLE SNOW ACROSS NE MO AND
W CNTRL MO LATE THIS AFTN INTO THIS EVENING IN ASSOC WITH WHAT/S
LEFT OF THE H500 LOW CURRENTLY ACROSS NE NEB AND SE SD. THIS SEEMS A
LOW PROB EVENT SO CHOSE TO COVER IT WITH FLURRIES.
THE FIRST SHORT WAVE CLEARS THE AREA LATE FRIDAY EVENING/FRIDAY
NIGHT WITH THE SECOND SHORT WAVE CLOSE ON ITS HEALS PASSING THRU
SATURDAY. LOW LEVEL MOISTURE REMAINS IN PLACE UNTIL THE PASSAGE OF
THE SECOND SHORT WAVE HAVE LEFT A CHANCE OF FLURRIES THRU THE NIGHT
AND INTO SATURDAY MORNING FOR AREAS EAST OF THE MS RIVER.
THINGS QUIET DOWN FOR THE WEEKEND WITH A 500MB RIDGE BUILDING IN AND
A 1030+MB SFC HIGH PASSING THRU. RETURN FLOW BEGINS BY SUNDAY AFTN.
THE PATTERN BECOMES ACTIVE AGAIN BY SUNDAY NIGHT WITH THE APPROACH
OF THE STHRN STREAM ENERGY.
THE MET GUIDANCE LOOKS TOO WARM FOR TODAY. LOCAL CLIMO INDICATES A
DIURNAL RISE OF 6 OR 7 DEGREES WHICH FITS THE MAV MOS BETTER. WITH
CLOUDS AND POTENTIAL LIGHT PRECIP...WENT ON THE COOLER SIDE OF
GUIDANCE TODAY AND WARMER TONIGHT. USED A BLEND FROM SATURDAY AND
BEYOND.
MILLER
&&
.LONG TERM...
ISSUED AT 353 AM CST FRI DEC 28 2012
.LONG TERM (MONDAY THRU THURSDAY)...
ENERGY DIVES DOWN THE WEST COAST OVER THE WEKND AND EJECTS OUT ON
MONDAY. MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT THAT PRECIP WILL
OVERSPREAD THE CWA MONDAY MORNING. THE GFS IS FURTHER NORTH WITH THE
PRECIP AND CONSEQUENTLY WARMER. IT ALSO LINGERS THE PRECIP LONGER AT
THE END OF THE EVENT. TEMPS WILL BE CRITICAL WITH THIS EVENT. THE
ECMWF AND GEM HAVE 850 TEMPS BELOW ZERO FOR THE ENTIRE EVENT WHILE
THE GFS HAS THE ZERO DEGREE 850MB LINE ALMOST UP TO THE MO RIVER.
SFC TEMPS WILL ULTIMATELY DETERMINE P-TYPE. MOST OF THE PRECIP SHOULD
OCCUR DURING THE DAY. WOULD HAVE A BETTER CHANCE FOR MORE SNOW IF
THE SYSTEM SLOWED AND THE BULK OF THE PRECIP OCCURRED AT NIGHT. THIS
EVENT CERTAINLY BEARS WATCHING AS THERE COULD BE ACCUMULATING SNOW
SOMEWHERE IN OUR CWA.
ANOTHER VORT MAX DROPS INTO THE DESERT SW EARLY NEXT WEEK AND
BECOMES CUT OFF BY THE MIDDLE OF THE WEEK. THE MODELS ARE HAVING A
TOUGH TIME DECIDING HOW TO HANDLE THIS SCENARIO. THE NTHRN STREAM
TRANSITIONS TO NW FLOW...SO LOOK FOR BELOW NORMAL TEMPS FOR THE
LATTER PART OF THE WORK WEEK. NOT CLEAR IF OR WHEN UPPER LEVEL FLOW
WILL PHASE AGAIN...SO THE FCST REMAINS DRY BEYOND TUESDAY.
MILLER
&&
.AVIATION...
ISSUED AT 1205 PM CST FRI DEC 28 2012
SC WILL CONTINUE TO DOMINATE ALL TAF SITES...WITH SNOWFALL
MENTIONED IN SHORT TERM AFD PERHAPS AFFECTING CPS LATE THIS
AFTERNOON/EARLY THIS EVENING. CIGS ARE GENERALLY RUNNING IN THE
3-4KFT RANGE ATTM...BUT STILL EXPECT THEM TO LOWER INTO MVFR CAT
LATER THIS AFTERNOON AND EVENING...ESPECIALLY AFTER PASSAGE OF
SURFACE TROF.
SPECIFICS FOR KSTL...HAVE HELD CIGS IN THE 3-4KFT RANGE FOR MUCH
OF THE AFTERNOON...WITH CIGS DIPPING INTO MVFR RANGE HEADING INTO
THE EARLY EVENING HOURS. ATTM BELIEVE MOST OF THE SNOWFALL OVER S
SECTIONS OF OUR CWA WILL REMAIN S OF THE STL AREA....BUT WILL
CAREFULLY MONITOR THIS DURING THE AFTERNOON.
TRUETT
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER WEATHER ADVISORY UNTIL 9 PM CST THIS EVENING FOR IRON MO-
MADISON MO-REYNOLDS MO-ST. FRANCOIS MO-STE. GENEVIEVE MO.
IL...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO MIDNIGHT CST
TONIGHT FOR CLINTON IL-MARION IL-RANDOLPH IL-WASHINGTON IL.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
149 AM CST FRI DEC 28 2012
.UPDATE...
.DISCUSSION...
SATELLITE WATER VAPOR AND THE RAP MODEL SHOW/SUGGEST SOME DRY AIR
IS FILTERING INTO NORTHWEST NEBRASKA. KIEN DROPPED 8 DEGREES IN ONE
HOUR. THE DRY AIR WILL ENHANCE RADIATIONAL COOLING ALLOWING TEMPS
TO FALL WELL BELOW ZERO. A NEW FORECAST IS OUT FOR TEMPERATURES
ACROSS NORTHWEST NEBRASKA. ALSO ADDED SCATTERED FLURRIES FOR THE
SHORT WAVE MOVING THROUGH THE FCST AREA OVERNIGHT.
&&
.PREV DISCUSSION... /ISSUED 1155 PM CST THU DEC 27 2012/
AVIATION...
LOW PRESSURE SYSTEM CONTINUES TO PUSH ACROSS S DAKOTA...WITH WRAP
AROUND MVFR CIGS AND LIGHT SNOW IMPACTING MUCH OF NORTHERN NEB
OVERNIGHT. EXPECT BKN025 TO BKN050 TO CONTINUE TO IMPACT MUCH OF
THE AREA EARLY TONIGHT...THEN LINGER OVER N CENTRAL TERMINALS
INTO THE MORNING HOURS. HAVE INCLUDING MVFR CIGS FOR KVTN
TERMINAL...HOWEVER CONFIDENCE IS MARGINAL. LIGHT SNOW OR FLURRIES
TO ALSO IMPACT AREAS WITH THE LOWEST CIGS...ALTHOUGH VSBY SHOULD
REMAIN VFR OR POSSIBLY BRIEFLY TO 4SM OR 5SM. IMPROVING CONDITIONS
TO VFR FROM SOUTHWEST TO NORTHEAST DURING MORNING HOURS TOMORROW.
LEADING TO WIDESPREAD VFR FOR THE AFTERNOON AND EVENING
HOURS...ALTHOUGH WILL STILL BE SOME VFR HIGH CLOUDS IN THE AREA.
PREV DISCUSSION... /ISSUED 309 PM CST THU DEC 27 2012/
SYNOPSIS...
H5 TROUGH OVER WESTERN CONUS WITH CLOSED LOW OVER SOUTHEAST SOUTH
DAKOTA AND ANOTHER OVER THE NORTHEAST US. STRONG RIDGE INTO THE
PACIFIC NORTHWEST.
DISCUSSION...
UPPER LOW CONTINUES TO SPIN OVER SOUTHERN SOUTH DAKOTA WITH
DEFORMATION ZONE BACK THROUGH NORTHERN NEBRASKA. AREAS OF LIGHT
SNOW OR FLURRIES DIMINISHING. LOOKING AT THE BUFR SOUNDINGS DEEP
SATURATED LAYER IN DENDRITIC ZONE AND WILL NOT TAKE MUCH LIFT TO
GET FLURRIES OR LIGHT SNOW LATE THIS AFTERNOON AND EVENING. SOME
SUN TRYING TO BREAK THROUGH THIS AFTERNOON. CURRENT OBSERVATIONS
HAVE LIGHT SNOW EAST OF A LINE FROM ALLIANCE TO LEXINGTON. HAVE
KEPT MENTION OF LIGHT SNOW IN THE FORECAST OVER NORTHERN NEBRASKA
THROUGH MIDNIGHT AND THEN OVER NORTH CENTRAL THROUGH FRIDAY
MORNING. HAVE CUT BACK ON POPS A LITTLE BUT LOOKS TO BE A HIGH POP
LOW PRECIP FORECAST SITUATION. 20 AND 25 TO ONE RATIOS HAVE BEEN
COMMON TODAY. SKY FORECAST TRICKY. SOME BREAKS AS MENTIONED OVER
SOUTHERN NEBRASKA. IF SKIES CLEAR 850MB TEMPERATURES BOTTOM OUT
AROUND -14C AND SOME BELOW ZERO TEMPERATURES ALONG THE PLATTE
RIVER VALLEY AND OVER THE NORTHWEST. SKIES TO BECOME PARTLY CLOUDY
ON FRIDAY AND WITH WEST TO NORTHWEST DOWNSLOPE WINDS AND SOME SUN
EXPECT TEMPERATURES TO ROCKET INTO THE LOW 20S TO THE WEST AND
TEENS EAST. WILL NOT BE ABLE TO GO MUCH HIGHER THAN THIS DUE TO
-12 850MB TEMPERATURES OVER HEAD. NORTHWEST WINDS AT 5 TO 15 MPH
OVER NORTH CENTRAL NEBRASKA TOMORROW MAY CAUSE SOME DRIFTING ON
EAST WEST SECONDARY ROADS. DO NOT BELIEVE THAT THERE SHOULD BE ANY
RESTRICTIONS TO VISIBILITY. ANOTHER SECONDARY WAVE MOVES ACROSS
THE NORTHEAST FRIDAY NIGHT WITH THE RIDGE AND WARMER AIR ALOFT
BUILDING TO THE EAST THROUGH THE DAY SATURDAY AND SUNDAY.
TEMPERATURES RISE TO THE 30S SATURDAY AND SUNDAY. HAVE KEPT THEM
ON COOLER SIDE OF GUIDANCE WITH SNOW COVER AND POSSIBILITY OF FOG
FREEZING FOG DEVELOPING OVER THE AREA WITH SNOW MELT. WILL ADDRESS
THE POSSIBILITY DAY TO DAY. COOLER AIR TO BE DRAWN INTO FORECAST
AREA MONDAY AS A PROGRESSIVE POSITIVELY TILTED TROUGH BRINGS
ENERGY OUT OF THE FOUR CORNERS ONTO THE CENTRAL PLAINS. THE NEW
ECMWF HAS BROUGHT THIS ENERGY FURTHER NORTH WITH THE LATEST RUN
MORE IN LINE WITH THE GFS SOLUTION. HAVE LEFT DRY FOR NOW BUT WILL
HAVE TO BE WATCHED. STRONG SOUTHERN STREAM JET 140KT+ WILL MOVE
THIS SYSTEM ALONG. ECMWF STILL FORMING A CUTOFF LOW TUESDAY OVER
SOUTHWEST CONUS AND MOVING IT ACROSS THE SOUTHERN PLAINS. THIS
WOULD LEAVE THE FORECAST AREA DRY WITH TEMPERATURES NEAR NORMAL
FOR THE SEASON 36.
HYDROLOGY...
ICE JAMMING ALONG THE NORTH PLATTE RIVER WILL LEAD TO MINOR FLOODING
OF THE RIVER UPSTREAM OF LAKE MCCONAUGHY AND NEAR THE CITY OF NORTH
PLATTE. DUE TO THE DYNAMIC NATURE OF ICE JAMMING...SUDDEN
FLUCTUATIONS MAY OCCUR...ESPECIALLY SINCE AIR TEMPERATURES ARE
FORECAST TO REMAIN COLD THROUGH SUNDAY MORNING. THE FLOOD WARNING
CONTINUES FOR THE NORTH PLATTE RIVER NEAR LEWELLEN AND NORTH PLATTE.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM/EXTENDED...BROOKS
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1129 PM CST THU DEC 27 2012
.AVIATION...06Z KGRI TAF. MVFR CONDITIONS EXPECTED THROUGH
16Z...WITH VFR CONDITIONS FORECAST 16Z ONWARD. STRATUS CONTINUES
ACROSS THE AREA WITH CEILINGS GENERALLY IN THE 3000FT AGL TO
4000FT AGL RANGE. THERE IS A CHANCE CEILINGS COULD DROP BELOW
3000FT AGL AT KGRI...BUT GUIDANCE SUGGESTS CEILINGS WILL REMAIN
ABOVE 3000FT AGL AND PLAY CLOSE TO THIS GUIDANCE IN THE TAF.
VISIBILITY RESTRICTION TO AROUND 3SM IN LIGHT SNOW AND PERHAPS BR
WILL ALSO PERSIST AT THE TERMINAL HEADING INTO FRIDAY
MORNING...WITH UNRESTRICTED VISIBILITY CURRENTLY FORECAST 16Z
ONWARD. THE SURFACE WIND WILL REMAIN LIGHT AND VARIABLE
TONIGHT...BECOMING MORE ESTABLISHED FROM THE NORTHWEST AT AROUND
11KTS DURING THE DAY FRIDAY.
&&
.PREV DISCUSSION... /ISSUED 707 PM CST THU DEC 27 2012/
UPDATE...MODEL INITIALIZATION FROM THE RAP AS OF 23Z INDICATES A
WEAK LONGWAVE TROUGH OVER THE WESTERN HALF OF THE CONUS WITH
MODEST RIDGING OVER THE EAST. MID AND UPPER LEVEL JET ENERGY
EXTENDS FROM WEST TEXAS...EAST/NORTHEAST INTO THE LOWER
MISSISSIPPI VALLEY AND SOUTHEASTERN CONUS. TROPOSPHERIC FLOW OVER
THE CENTRAL PLAINS REMAINS FAIRLY WEAK AS A RESULT...MAXING OUT AT
~70KTS NEAR 300MB PER 23Z RAP ANALYSIS SOUNDING DATA FOR KGRI.
WATER VAPOR IMAGERY INDICATES A MID LEVEL LOW OVER NORTHERN
NEBRASKA AND SOUTHERN SOUTH DAKOTA...MOVING EAST/NORTHEAST.
INCREASED VALUES OF MID LEVEL MOISTURE ARE ALSO NOTED OVER
SOUTHERN PORTIONS OF THE CONUS...EXTENDING ALONG THE LEVEL JET
AXIS. MID LEVEL MOISTURE FARTHER NORTHWEST HOWEVER...ACROSS OUR
REGION...REMAINS FAIRLY MEAGER. AT THE SURFACE A STATIONARY
BOUNDARY IS NOTED EXTENDING ACROSS PORTIONS OF CENTRAL AND EASTERN
KANSAS AND AS OF 00Z WAS NOTED FROM NEAR KMHK...TO NEAR KHUT AND
NEAR KICT. THE LOW LEVEL WIND FIELD ACROSS OUR AREA REMAINS FROM
THE EAST/NORTHEAST AS A RESULT...WITH THE SOUTHEASTERLY LOW LEVEL
WIND FIELD RELEGATED TO THE SOUTHEAST OF OUR AREA...SOUTHEAST OF
THE LOW LEVEL BAROCLINIC ZONE.
RAP DATA SUGGESTS THE PRIMARY AXIS OF MID LEVEL THERMAL ADVECTION
AND DPVA HAVE DEPARTED OUR AREA TO THE NORTHEAST AND WITH AN
OVERALL LACK IN OMEGA...SUBSTANTIAL SNOWFALL SHOULD BE HARD TO
COME BY ACROSS OUR AREA THROUGH THE REST OF TONIGHT. THAT BEING
SAID...THERMAL ADVECTION ACROSS THE AFOREMENTIONED LOW LEVEL
BAROCLINIC ZONE IS PROMOTING ISENTROPIC UPGLIDE AND
SATURATION...PRIMARILY BETWEEN THE 275 AND 285K SURFACES. STRATUS
HAS RESULTED ACROSS MUCH OF OUR AREA...WITH CEILINGS GENERALLY
BETWEEN 1000 AND 3000FT AGL NOTED AS OF 00Z. SOUNDINGS FROM ACROSS
THE CWA PER RAP ANALYSIS DATA SUGGESTS THIS STRATUS EXTENDS
VERTICALLY TO NEAR 800MB...WITH THE TEMPERATURE NEAR 850MB JUST
BARELY BREAKING INTO THE DENDRITIC ZONE AT AROUND -12 OR -13 C.
PERIODIC SNOW FLURRIES HAVE BEEN NOTED ACROSS MUCH OF THE CWA THIS
EVENING AS A RESULT. GIVEN THAT THE PRIMARY AXIS OF OMEGA HAS
SHIFTED WELL NORTHEAST OF OUR AREA...OPTED TO REMOVE POPS FROM
ACROSS THE CWA THROUGH THE REST OF TONIGHT...BUT ALSO EXTENDED
ISOLATED FLURRIES ACROSS THE ENTIRE CWA TO ACCOUNT FOR THE CURRENT
ACTIVITY. NOTHING MORE THAN TRACE AMOUNTS OF SNOWFALL ARE
ANTICIPATED ACROSS THE CWA THROUGH TONIGHT.
THERE ARE SOME INDICATIONS...IN PARTICULAR FROM THE NAM AND
RAP...THAT LOWER TROPOSPHERIC RH VALUES COULD BE HIGH ENOUGH FOR
THE DEVELOPMENT OF PATCHY FOG LATER TONIGHT...ESPECIALLY AS
TEMPERATURES NEAR 850MB WARM SLIGHTLY...AS SUGGESTED BY THE NAM
AND RAP...THUS MOVING THE CURRENT STRATUS LAYER OUT OF THE
DENDRITIC ZONE. IT APPEARS THE MOST LIKELY AREA TO OBSERVE SUCH
DEVELOPMENT WOULD BE ACROSS OUR SOUTHEASTERN CWA WHICH IS WHERE
THE HIGHEST LOWER TROPOSPHERIC MOISTURE WILL RESIDE. CONTEMPLATED
ADDING LIGHT FREEZING DRIZZLE TO THE GRIDS FOR TONIGHT AS IT
APPEARS AS THOUGH 0-0.5KM RH VALUES WILL ALSO BE VERY HIGH...NOT
JUST AT THE SURFACE. THAT BEING SAID...THE RAP AND NAM BOTH
SUGGEST LOW LEVEL TURBULENT MIXING WILL REMAIN VERY WEAK WITH
0-0.5KM BULK SHEAR UNDER 10KTS THROUGH MUCH OF THE NIGHT...THUS
MAKING FOG PRODUCTION THE MORE LIKELY SCENARIO. GIVEN ALL
THIS...WENT AHEAD AND INSERTED PATCHY FREEZING FOG TO THE GRIDS
FOR OUR SOUTHEASTER CWA FOR TONIGHT. THE VISIBILITY AT LOCATIONS
SUCH AS KK61 AND KCNK HAVE DROPPED TO AROUND 5SM AT TIMES THIS
EVENING AND THIS IS A TREND WHICH WILL NEED TO BE MONITORED.
PREV DISCUSSION... /ISSUED 343 PM CST THU DEC 27 2012/
SHORT TERM...TONIGHT THROUGH FRIDAY.
MAIN CHALLENGE WILL BE DETERMINING CHANCES OF SNOW TONIGHT. TROUGH
AXIS HAS YET TO CROSS TO THE EAST...BUT MOST OF THE ENERGY
RESPONSIBLE FOR ACCUMULATING SNOW HAS SHIFTED NORTH. THEREFORE CUT
BACK CHANCES OF PRECIPITATION CONSIDERABLY...YET KEPT WIDESPREAD
FLURRIES FOR MOST OF THE CWA THIS EVENING...WITH LINGERING SCATTERED
FLURRIES OVERNIGHT AS THE TROUGH AXIS FINALLY MAKES ITS WAY TO THE
EAST OF THE CWA OVERNIGHT. SURFACE HIGH BUILDS IN FOR FRIDAY...BUT
STRATUS IS FORECAST TO BE STUBBORN TO LEAVE. STILL A LOT OF COLD AIR
AROUND WITH SNOW ON THE GROUND AND CLOUDY SKY...THIS WILL ADD UP TO
A COLDER THAN NORMAL DAY. YANKED FREEZING DRIZZLE FROM THE
SOUTHEASTERN CWA AS TEMPERATURES SHOULD BE A LITTLE TOO COLD AT THE
TOP OF THE LOW-LEVEL SATURATION LAYER TO ALLOW SUPERCOOLED WATER TO
REMAIN...WITH PERHAPS SNOWGRAIN TYPE PRECIPITATION IF ANYTHING THIS
EVENING. ALL IN ALL...MOST OF ANY APPRECIABLY ACCUMULATING SNOW HAS
ENDED FOR THE CWA.
LONG TERM...FRIDAY NIGHT THROUGH THURSDAY. BEGINNING FRIDAY
NIGHT...AN UPPER TROUGH AXIS EXITS THE NORTHERN AND CENTRAL PLAINS.
MODELS INDICATE POTENTIAL FOR LOW CLOUDS/STRATUS LINGERING ACROSS
OUR EASTERN ZONES FOR A FEW HOURS DURING THE EVENING...THEN CLOUDS
LOOK TO DEPART BY MIDNIGHT WITH DEPARTING TROUGH AND HEIGHTS RISES
WHILE DOWNSLOPE LLVL FLOW DEVELOPS. THE COLD AIRMASS BEGINS TO
DISLODGE ON SATURDAY AS AN INTERMOUNTAIN RIDGE EXPANDS EASTWARD ONTO
THE PLAINS WITH WARMING AIDED BY A WESTERLY DOWNSLOPE WIND
COMPONENT. THE SHORTWAVE RIDGE AXIS BREAKS DOWN HEADING INTO SUNDAY
AS AN UPSTREAM TROUGH CROSSES THE NORTHERN PLAINS. THE ASSOCIATED
COLD FRONTAL PASSAGE ASSOCIATED WITH THIS NEXT TROUGH HOLDS OFF
UNTIL SUNDAY AFTN/EVE SO SUNDAY IS STILL LOOKING LIKE THE WARMEST
DAY OF THE NEXT SEVERAL DAYS AHEAD OF THIS NEXT COLD FRONT. WILL
AIM FOR HIGHS RIGHT AROUND 30 DEGREES WITH SOME MID/UPPER 30S IN NC
KANSAS WHERE SNOW PACK/DEPTH IS NOT AS MUCH OF AN ISSUE. WILL NEED
TO MONITOR FOR POTENTIAL FOG DEVELOPMENT IF WE CAN GET SOME DECENT
MELTING OF THE SNOW.
A 1030MB TO 1035MB SFC HIGH...WITH THE STRENGTH DEPENDENT UPON THE
MODEL...BUILDS SOUTH BEHIND THE FRONT SUNDAY NIGHT INTO MONDAY AND
SETTLES IN UNTIL AROUND THE TUESDAY TIME FRAME WITH A GENERAL COLD
WINTER AIRMASS IN PLACE. A FEW DAYS AGO MODELS WERE INDICATING MUCH
COLDER ARCTIC AIR THAN WHAT IS SUGGESTED AT THIS TIME NOW. EXTENDED
MODELS DIVERGE EARLY TO MID WEEK OF NEXT WEEK WITH HANDLING OF
SOUTHWEST CONUS SYSTEM WITH ECMWF STRONGER THAN THE MORE PROGRESSIVE
GFS...AND CLOSES OFF THE SYSTEM VS GFS OPEN WAVE. CONFIDENCE LOWERS
BY MID WEEK OF NEXT WEEK DUE TO MODEL DIFFERENCES AND WILL MAINTAIN
STATUS QUO FOR TEMPS AND NOT SWING WARMER/COOLER OR WETTER UNTIL
MODELS COME INTO BETTER AGREEMENT.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE/AVIATION...BRYANT
SHORT TERM...HEINLEIN
LONG TERM...FAY
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
712 PM EST SAT DEC 29 2012
.SYNOPSIS...
A WINTER STORM WILL TRACK FROM OFF THE NEW JERSEY COAST TO OFF
THE NEW ENGLAND COAST TONIGHT. THIS STORM WILL BRING A WIDESPREAD
4 TO 8 INCHES OF SNOW TO CENTRAL NEW YORK AND NORTHEAST
PENNSYLVANIA. A COLD NORTHWEST FLOW BEHIND THIS WINTER STORM WILL
GENERATE LAKE EFFECT SNOW SHOWERS FOR UPSTATE NEW YORK AND FAR
NORTHEASTERN PENNSYLVANIA TONIGHT THROUGH SUNDAY NIGHT. A COLD AND
UNSETTLED WEATHER PATTERN WILL REMAIN THROUGH NEXT WEEK WITH MORE
SNOW SHOWERS AND MUCH COLDER AIR INVADING THE REGION.
&&
.NEAR TERM /THROUGH SUNDAY/...
6 PM UPDATE... WE JUST TWEAKED WX/POP GRIDS SLIGHTLY...TO FOLLOW
THE BACK-EDGE OF THE STEADY SYNOPTIC-SCALE SNOW EWD AND OUT OF THE
FA IN THE NEXT 2-3 HRS. THIS BACK EDGE LINES UP NICELY WITH THE
END LN OF UPR-LVL PV ADVECTION ON THE RUC MODEL...ASSOCD WITH THE
PASSING VIGOROUS SHRT WV.
LTR TNT...AS THE LOW AND MID-LVL WINDS VEER TO NWLY AND PICK
UP...WE`RE STILL EXPECTING SOME LAKE-ENHANCED SNOW BANDS TO
FORM ACRS CNY...GIVEN STILL DEEP SYNOPTIC MOISTURE. OUR GOING FCST
HANDLES THIS SCENARIO WELL...AND WE`VE GONE WITH THE PSBLTY OF
ANOTHER 1-2" FROM 06-12Z NEAR THE I-81 CORRIDOR...AND N OF KBGM.
AFTER 12Z...THE DEEPER MOISTURE SHOULD GET SWEPT EWD...WITH A
CORRESPONDING DECREASE IN SNOWFALL INTENSITY/COVERAGE.
PREV DISC... DECIDED TO UPGRADE TO A WINTER STORM WARNING FOR
COUNTIES IN THE MIDDLE OF OUR FORECAST AREA FROM BRADFORD COUNTY
PA NORTHEAST TO DELAWARE/OTSEGO CO/S BASED ON SPOTTER REPORTS AND
RADAR SNOW ALGORITHM ACCUMULATIONS WHICH INDICATE A SWATH OF 4-5
INCHES. KCCX RADAR SHOWING BANDS OF HEAVIER SNOW STILL LIFTING
NORTHWARD ASSOCIATED MORE WITH THE DEVELOPING COASTAL SYSTEM THAT
WAS INITIALLY PROGGED TO STAY EAST OF THE REGION. FEEL ENOUGH
MODERATE TO HEAVY SNOW STILL TO COME FOR AT LEAST 3-4 MORE HOURS
IN THE ABV AREAS WHICH IS GOOD FOR ANOTHER 2-3 INCHES. THIS WILL
GET US TO LOW END WARNING CRITERIA. WENT 4-6 INCHES IN THE REST OF
NE PA/SULLIVAN CO FOR NOW. BUT AM NOW CONCERNED THAT MORE OF THIS
PRECIPITATION SHIELD WITH THE COASTAL STORM MAY IMPACT
SULLIVAN/PIKE AND SRN WAYNE CO/S AND POSSIBLY EVEN
LACKAWANNA/LUZERNE COUNTIES. MAY HAVE TO UPGRADE LATER...WILL BE
WATCHING SPOTTER REPORTS CLOSELY. FOR NRN ZONES...LESS SNOW HAS
FALLEN AND BELIEVE HEAVIEST WILL REMAIN TO THE SOUTH...SO WENT 4-7
INCHES THERE WHICH IS HIGH END ADVY.
MAIN UPPER LEVEL WAVE WILL MOVE ACROSS THE FORECAST AREA BY EARLY
THIS EVENING AS COASTAL LOW AND ITS ASSOCIATED PRECIPITATION
SHIELD SPINS UP RAPIDLY. SNOW WILL TAPER DOWN THIS EVENING BUT
FLOW WILL REMAIN MOIST AND TURN TO THE NW THRU THE DEPTH OF THE
TROPOSPHERE WHICH MEANS LAKE EFFECT/ENHANCED SNOW SHOWERS FOR A
LARGE PART OF C NY AND PORTIONS OF NE PA. BELIEVE ANOTHER COUPLE
INCHES OR SO POSSIBLE LATER TONIGHT AFTER MAIN SYNOPTIC SCALE
SNOW SHIELD MOVES EAST BY 3Z.
MODEL SOUNDINGS CONT TO SHOW A NW FLOW WITH THE TOP OF THE
INVERSION LAYER ARND -12C WITH MODERATE LAKE TEMP T0 850 MB TEMP
DIFFERENCES THRU SUN. THIS WILL KEEP LES SNOW SHOWERS GOING DOWNWIND
OF LAKE ONTARIO OVER A LARGE PART OF CENTRAL NY AND FAR NE PA THRU
SUNDAY. THE LES WILL WIND DOWN SUN NGT AS THE FLOW STARTS TO BACK
TO THE W IN ADVANCE OF THE NEXT WAVE.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
3 PM UPDATE...
ON MONDAY A RIDGE OF HIGH PRESSURE OVER THE ENTIRE EAST COAST WITH
RIDGING ALOFT WILL SHUT OFF THE LAKE EFFECT. MAX TEMPS CLOSE TO
FREEZING POINT WILL BE THE WARMEST OF THE WEEK.
THE FLOW WILL SHIFT TO SW AT LOW LEVELS AHEAD OF THE NEXT SYSTEM.
A STRONG COLD FRONT WITH LIMITED MOISTURE MOVES THROUGH LATE
MONDAY NIGHT AND EARLY TUESDAY WITH SNOW SHOWERS. BEHIND THE FRONT
THE DEEP FLOW TURNS BACK TO NW SO LAKE EFFECT WITH THE CAA. THIS
EVENT MAY NEED AN ADVISORY FOR CENTRAL NY WITH SEVERAL INCHES WITH
THE FRONT FOLLOWED BY SEVERAL MORE OF LAKE EFFECT. DECENT LIFT
THROUGH THE THICK DENDRITE ZONE. NAM HAS MUCH MORE MOISTURE THAN
SREF AND GFS. 15K FT COMPARED WITH LESS THAN 10K. BELIEVE NAM WILL
BE CLOSER TO THE TRUTH.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
3 PM UPDATE...
FOLLOWED HPC GUIDANCE. WITH A GOOD SNOW PACK NOW HERE AND ACROSS
CANADA AND THE NRN TIER OF THE CONUS COLD AIR WILL ONLY STRENGTHEN
WITH EACH CLIPPER. STILL ONLY 5 TO 10 DEGREES BELOW NORMAL. FOR
THE MOST PART NUISANCE SNOW WITH NO BIG SYNOPTIC STORMS TAPPING
INTO THE ATLANTIC. A COLD FRONT FROM THE NW WITH LITTLE MOISTURE
BUT -16C AT 850MB WILL GET SOME LAKE EFFECT GOING. A MODERATE
EVENT BUT DOES NOT LAST LONG WITH WEAK HIGH PRESSURE BUILDING IN
WED NGT AND THU. A SFC LOW AND SHORT WAVE WILL DROP SE FRI NGT AND
SAT WITH SNOW SHOWERS. ANOTHER SHOT OF COLD AIR AND LAKE
ENHANCEMENT. WITH THE FRONT THEN LAKE EFFECT.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
WITH THE BULK OF SYNOPTIC SNOW GRADUALLY SHIFTING OFF TO THE
EAST...ATTENTION NOW SHIFTING TO DEVELOPING LAKE ENHANCED SNOW
SHWRS SOUTH OF LAKE ONTARIO AND THE FINGER LAKES THIS EVENING.
LATEST RADAR TRENDS NOW SHOWING THE TRAILING EDGE OF SYNOPTIC
SNOWS GRADUALLY STRETCHED OUT ALONG THE I-81 CORRIDOR AND WORKING
EAST. AS WE GO THROUGH THE NIGHT...EXPECT IMPROVING CONDITIONS AT
AVP...ELM...RME AS LAKE EFFECT ACTIVITY MAKES MINIMAL IMPACT. AT THE
REMAINING SITES OF SYR...ITH...BGM...EXPECT CONTINUED IFR
CONDITIONS AS LAKE EFFECT MOISTURE RESULTS IN DEVELOPING SNOW
SHWRS.
AFTER 12Z...CONDITIONS WILL BEGIN TO IMPROVE AT ALL SITES AS LOW-
LEVEL MOISTURE GETS SCOURED OUT. DESPITE THIS HOWEVER...BROAD
NORTHWEST FLOW WILL LEAD TO CONTINUED MVFR CIGS AT ALL SITES WITH
THE EXCEPTION OF AVP AND POTENTIALLY ELM THROUGH THE AFTERNOON
HRS. ADDITIONALLY...A TIGHTENING PRESSURE GRADIENT THROUGH THE
MORNING AND AFTERNOON WILL RESULT IN GUSTY NORTHWEST WINDS WITH
GUSTS AS HIGH AS 25 KTS POSSIBLE AT ALL LOCATIONS.
MON...VFR.
MON NGT TO WED NGT...MVFR/IFR ESPECIALLY FOR CNY TERMINALS IN LAKE
EFFECT SNOW SHWRS.
THU...MAINLY VFR.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...WINTER STORM WARNING UNTIL 9 PM EST THIS EVENING FOR
PAZ038>040.
WINTER WEATHER ADVISORY UNTIL 9 PM EST THIS EVENING FOR PAZ043-
044-047-048-072.
NY...WINTER STORM WARNING UNTIL 9 PM EST THIS EVENING FOR NYZ045-
046-055>057.
WINTER WEATHER ADVISORY UNTIL 9 PM EST THIS EVENING FOR NYZ009-
015>018-022>025-036-037-044-062.
&&
$$
SYNOPSIS...DJP
NEAR TERM...DJN/MLJ
SHORT TERM...TAC
LONG TERM...TAC
AVIATION...CMG
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
609 PM EST SAT DEC 29 2012
.SYNOPSIS...
A WINTER STORM WILL TRACK FROM OFF THE NEW JERSEY COAST TO OFF
THE NEW ENGLAND COAST TONIGHT. THIS STORM WILL BRING A WIDESPREAD
4 TO 8 INCHES OF SNOW TO CENTRAL NEW YORK AND NORTHEAST
PENNSYLVANIA. A COLD NORTHWEST FLOW BEHIND THIS WINTER STORM WILL
GENERATE LAKE EFFECT SNOW SHOWERS FOR UPSTATE NEW YORK AND FAR
NORTHEASTERN PENNSYLVANIA TONIGHT THROUGH SUNDAY NIGHT. A COLD AND
UNSETTLED WEATHER PATTERN WILL REMAIN THROUGH NEXT WEEK WITH MORE
SNOW SHOWERS AND MUCH COLDER AIR INVADING THE REGION.
&&
.NEAR TERM /THROUGH SUNDAY/...
6 PM UPDATE... WE JUST TWEAKED WX/POP GRIDS SLIGHTLY...TO FOLLOW
THE BACK-EDGE OF THE STEADY SYNOPTIC-SCALE SNOW EWD AND OUT OF THE
FA IN THE NEXT 2-3 HRS. THIS BACK EDGE LINES UP NICELY WITH THE
END LN OF UPR-LVL PV ADVECTION ON THE RUC MODEL...ASSOCD WITH THE
PASSING VIGOROUS SHRT WV.
LTR TNT...AS THE LOW AND MID-LVL WINDS VEER TO NWLY AND PICK
UP...WE`RE STILL EXPECTING SOME LAKE-ENHANCED SNOW BANDS TO
FORM ACRS CNY...GIVEN STILL DEEP SYNOPTIC MOISTURE. OUR GOING FCST
HANDLES THIS SCENARIO WELL...AND WE`VE GONE WITH THE PSBLTY OF
ANOTHER 1-2" FROM 06-12Z NEAR THE I-81 CORRIDOR...AND N OF KBGM.
AFTER 12Z...THE DEEPER MOISTURE SHOULD GET SWEPT EWD...WITH A
CORRESPONDING DECREASE IN SNOWFALL INTENSITY/COVERAGE.
PREV DISC... DECIDED TO UPGRADE TO A WINTER STORM WARNING FOR
COUNTIES IN THE MIDDLE OF OUR FORECAST AREA FROM BRADFORD COUNTY
PA NORTHEAST TO DELAWARE/OTSEGO CO/S BASED ON SPOTTER REPORTS AND
RADAR SNOW ALGORITHM ACCUMULATIONS WHICH INDICATE A SWATH OF 4-5
INCHES. KCCX RADAR SHOWING BANDS OF HEAVIER SNOW STILL LIFTING
NORTHWARD ASSOCIATED MORE WITH THE DEVELOPING COASTAL SYSTEM THAT
WAS INITIALLY PROGGED TO STAY EAST OF THE REGION. FEEL ENOUGH
MODERATE TO HEAVY SNOW STILL TO COME FOR AT LEAST 3-4 MORE HOURS
IN THE ABV AREAS WHICH IS GOOD FOR ANOTHER 2-3 INCHES. THIS WILL
GET US TO LOW END WARNING CRITERIA. WENT 4-6 INCHES IN THE REST OF
NE PA/SULLIVAN CO FOR NOW. BUT AM NOW CONCERNED THAT MORE OF THIS
PRECIPITATION SHIELD WITH THE COASTAL STORM MAY IMPACT
SULLIVAN/PIKE AND SRN WAYNE CO/S AND POSSIBLY EVEN
LACKAWANNA/LUZERNE COUNTIES. MAY HAVE TO UPGRADE LATER...WILL BE
WATCHING SPOTTER REPORTS CLOSELY. FOR NRN ZONES...LESS SNOW HAS
FALLEN AND BELIEVE HEAVIEST WILL REMAIN TO THE SOUTH...SO WENT 4-7
INCHES THERE WHICH IS HIGH END ADVY.
MAIN UPPER LEVEL WAVE WILL MOVE ACROSS THE FORECAST AREA BY EARLY
THIS EVENING AS COASTAL LOW AND ITS ASSOCIATED PRECIPITATION
SHIELD SPINS UP RAPIDLY. SNOW WILL TAPER DOWN THIS EVENING BUT
FLOW WILL REMAIN MOIST AND TURN TO THE NW THRU THE DEPTH OF THE
TROPOSPHERE WHICH MEANS LAKE EFFECT/ENHANCED SNOW SHOWERS FOR A
LARGE PART OF C NY AND PORTIONS OF NE PA. BELIEVE ANOTHER COUPLE
INCHES OR SO POSSIBLE LATER TONIGHT AFTER MAIN SYNOPTIC SCALE
SNOW SHIELD MOVES EAST BY 3Z.
MODEL SOUNDINGS CONT TO SHOW A NW FLOW WITH THE TOP OF THE
INVERSION LAYER ARND -12C WITH MODERATE LAKE TEMP T0 850 MB TEMP
DIFFERENCES THRU SUN. THIS WILL KEEP LES SNOW SHOWERS GOING DOWNWIND
OF LAKE ONTARIO OVER A LARGE PART OF CENTRAL NY AND FAR NE PA THRU
SUNDAY. THE LES WILL WIND DOWN SUN NGT AS THE FLOW STARTS TO BACK
TO THE W IN ADVANCE OF THE NEXT WAVE.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
3 PM UPDATE...
ON MONDAY A RIDGE OF HIGH PRESSURE OVER THE ENTIRE EAST COAST WITH
RIDGING ALOFT WILL SHUT OFF THE LAKE EFFECT. MAX TEMPS CLOSE TO
FREEZING POINT WILL BE THE WARMEST OF THE WEEK.
THE FLOW WILL SHIFT TO SW AT LOW LEVELS AHEAD OF THE NEXT SYSTEM.
A STRONG COLD FRONT WITH LIMITED MOISTURE MOVES THROUGH LATE
MONDAY NIGHT AND EARLY TUESDAY WITH SNOW SHOWERS. BEHIND THE FRONT
THE DEEP FLOW TURNS BACK TO NW SO LAKE EFFECT WITH THE CAA. THIS
EVENT MAY NEED AN ADVISORY FOR CENTRAL NY WITH SEVERAL INCHES WITH
THE FRONT FOLLOWED BY SEVERAL MORE OF LAKE EFFECT. DECENT LIFT
THROUGH THE THICK DENDRITE ZONE. NAM HAS MUCH MORE MOISTURE THAN
SREF AND GFS. 15K FT COMPARED WITH LESS THAN 10K. BELIEVE NAM WILL
BE CLOSER TO THE TRUTH.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
3 PM UPDATE...
FOLLOWED HPC GUIDANCE. WITH A GOOD SNOW PACK NOW HERE AND ACROSS
CANADA AND THE NRN TIER OF THE CONUS COLD AIR WILL ONLY STRENGTHEN
WITH EACH CLIPPER. STILL ONLY 5 TO 10 DEGREES BELOW NORMAL. FOR
THE MOST PART NUISANCE SNOW WITH NO BIG SYNOPTIC STORMS TAPPING
INTO THE ATLANTIC. A COLD FRONT FROM THE NW WITH LITTLE MOISTURE
BUT -16C AT 850MB WILL GET SOME LAKE EFFECT GOING. A MODERATE
EVENT BUT DOES NOT LAST LONG WITH WEAK HIGH PRESSURE BUILDING IN
WED NGT AND THU. A SFC LOW AND SHORT WAVE WILL DROP SE FRI NGT AND
SAT WITH SNOW SHOWERS. ANOTHER SHOT OF COLD AIR AND LAKE
ENHANCEMENT. WITH THE FRONT THEN LAKE EFFECT.
&&
.AVIATION /23Z SATURDAY THROUGH THURSDAY/...
1230 PM UPDATE...
IFR VSBYS MAJORITY OF THE DAY WITH SNOW HEAVY AT TIMES. IFR CIGS
TOO MOSTLY AT THE HIGHER ELEV SITES OF BGM AND ITH. SOME VSBYS
UNDER A QUARTER MILE IN HEAVY SNOW THIS AFTN WILL DROP CONDITIONS
BELOW FLIGHT MINIMUMS. IFR TO CONTINUE THROUGH THE EVENING BEFORE THE
SNOW TAPERS OFF LATE TONIGHT. LOW LEVEL FLOW SHIFTS TO NW THIS
EVENING PROVIDING LAKE EFFECT ENHANCEMENT TO THE LINGERING SNOW.
FOR SUNDAY MVFR CONDITIONS IN NY WITH LAKE EFFECT SNOW SHOWERS AND
VFR AT KAVP.
E WINDS AT 5 TO 10 KTS SHIFTING TO NW LATE THIS AFTN...THEN
CONTINUING TONIGHT. SUNDAY NW WINDS AT 10 TO 15 KTS.
OUTLOOK...
SUN AFTN AND NGT...MVFR/IFR POSSIBLE FOR CNY TERMINALS...IN LAKE
EFFECT SN ACTIVITY.
MON...VFR.
MON NGT TO WED NGT...MVFR/IFR ESPECIALLY FOR CNY TERMINALS.
THU...VFR.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...WINTER STORM WARNING UNTIL 9 PM EST THIS EVENING FOR
PAZ038>040.
WINTER WEATHER ADVISORY UNTIL 9 PM EST THIS EVENING FOR PAZ043-
044-047-048-072.
NY...WINTER STORM WARNING UNTIL 9 PM EST THIS EVENING FOR NYZ045-
046-055>057.
WINTER WEATHER ADVISORY UNTIL 9 PM EST THIS EVENING FOR NYZ009-
015>018-022>025-036-037-044-062.
&&
$$
SYNOPSIS...DJP
NEAR TERM...DJN/MLJ
SHORT TERM...TAC
LONG TERM...TAC
AVIATION...TAC
AREA FORECAST DISCUSSION
NWS BISMARCK ND
904 PM CST SAT DEC 29 2012
.DISCUSSION...LATEST SUITE OF SATELLITE IMAGERY CONTINUES TO SHOW
SCT MID/HIGH CLOUDS IN THE WEST...BKN HIGH CLOUDS IN THE
NORTHWEST WITH CLEAR SKIES EAST CENTRAL. WARM FRONT LOCATED FROM
AROUND MINOT SOUTH TO BISMARCK WITH A LARGE WEST/EAST TEMPERATURE
GRADIENT...WITH UPPER TEENS WEST TO AROUND ZERO EAST CENTRAL.
TEMPERATURES WILL ONLY FALL SLOWLY OVERNIGHT IN THE WEST AND SHOW
SIGNS OF RISING A BIT IN THE NORTHWEST AND NORTH CENTRAL AS THE
COLD FRONT NEARS. THE RUC13 SEEMED TO HANDLE THE CURRENT/HOURLY
TEMPERATURE SCENARIO WELL AND HAVE FOLLOWED. LATEST 00Z NAM
FOLLOWS THE 18Z MODEL RUN WITH NEAR ZERO MEASURABLE PRECIPITATION
SUNDAY FOR JUST ABOUT ALL OF WESTERN AND CENTRAL NORTH DAKOTA.
WILL AWAIT THE GFS/ECMWF/SREF BEFORE GOING FINAL WITH A REDUCTION
OF POPS. WOULD STILL EXPECT FLURRIES WITH THE LOWER CLOUDS SUNDAY
WHICH WILL INFILTRATE THE NORTHWEST AND NORTH CENTRAL BY 12Z
SUNDAY AND THEN SAG SOUTH DURING THE DAY. 00Z NAM/BUFR SOUNDINGS
STILL INDICATE NORTHWEST WINDS BEHIND THE FRONT AT AROUND 15 MPH
WITH GUSTS TO 20 MPH...THUS DRIFTING SNOW OFF CURRENT SNOWCOVER
WILL LIKELY OCCUR...BUT ANY SIGNIFICANT REDUCTION TO VISIBILITY DUE
TO BLOWING SNOW SHOULD REMAIN ISOLATED. HAVE ADJUSTED HOURLY
TEMPERATURES UP SLIGHTLY OVERNIGHT IN THE WEST AND NORTH CENTRAL
AND SLOWED DOWN THE ADVANCEMENT OF OVERCAST CONDITIONS THROUGH
SUNDAY MORNING.
&&
.AVIATION...LATEST SATELLITE IMAGERY SHOWS BKN VFR CIGS INTO
SOUTHWEST SASKATCHEWAN...WITH MVFR CIGS NOW WORKING SOUTHEAST FROM
SOUTH CENTRAL SASKATCHEWAN. AT THIS RATE...EXPECT SCT/BKN VFR
CIGS TO CONTINUE ACROSS THE AERODROMES THROUGH 12Z SUNDAY.
THEREAFTER...MVFR CIGS WILL GRADUALLY DESCEND FROM NORTH TO SOUTH
FOLLOWING THE PASSAGE OF A COLD FRONT. THUS EXPECT MVFR CIGS
INITIALLY AT KISN AND KMOT BETWEEN 12Z AND 15Z...THEN INTO
KDIK/KBIS BETWEEN 18Z AND 00Z MON...THEN INTO KJMS AFTER 00Z
MONDAY. WINDS WILL SHIFT TO THE NORTHWEST AROUND 15KT.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
DISCUSSION/AVIATION...KS
AREA FORECAST DISCUSSION
NWS BISMARCK ND
552 PM CST SAT DEC 29 2012
.DISCUSSION...LATEST WATER VAPOR IMAGERY SHOWS UPPER RIDGING
ACROSS WESTERN AND CENTRAL NORTH DAKOTA WITH WARM AIR ADVECTION
EVIDENT AS SCT MID/HIGH CLOUDS APPROACH WESTERN AND PORTIONS OF
CENTRAL NORTH DAKOTA. AT THE SURFACE...A WARM FRONT WAS LOCATED
FROM NEAR MINOT TO BISMARCK AND SOUTHEAST BETWEEN LINTON AND
OAKES. A BAND OF LOW CLOUDS FROM ROLLA STRETCHES SOUTHEAST INTO
JAMESTOWN...BUT THIS AREA STEADILY MOVING EAST. THE RUC13 925-850MB
RH FIELD HAS THIS ACCURATELY DEPICTED AND WILL FOLLOW FOR THE
OVERNIGHT PERIOD. A COLD FRONT OVER SOUTH CENTRAL CANADA WILL
CONTINUE TO SINK SOUTH...CROSSING THE NORTHWEST ZONES BETWEEN 09Z-
12Z SUNDAY AND THROUGH THE CENTRAL AND SOUTHERN ZONES DURING THE
LATE MORNING AND AFTERNOON. PRECIPITATION/POP TRENDS BASED ON THE
12Z/18Z MODELS APPEAR MUCH DRIER/LOWER...BUT WILL AWAIT THE FULL
00Z MODEL SUITE BEFORE MAKING ANY CHANGES. LOW CLOUDS/OVERCAST
CONDITIONS WILL FOLLOW THE FRONT SUNDAY FROM NORTHWEST TO SOUTHEAST
DURING THE DAY.
&&
.AVIATION...FOR THE 00Z TAF ISSUANCE...VFR CIGS ACROSS THE
AERODROMES EXPECTED THROUGH 12Z SUNDAY. THEREAFTER...MVFR CIGS
WILL GRADUALLY DESCEND FROM NORTH TO SOUTH FOLLOWING THE PASSAGE
OF A COLD FRONT. THUS EXPECT MVFR CIGS INITIALLY AT KISN AND KMOT
BETWEEN 12Z AND 15Z...THEN INTO KDIK/KBIS BETWEEN 18Z AND 00Z
MON...THEN INTO KJMS AFTER 00Z MONDAY. WINDS WILL SHIFT TO THE
NORTHWEST AT AROUND 15KT.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION/AVIATION...KS
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1025 AM CST FRI DEC 28 2012
.DISCUSSION...
MAIN CHALLENGES WILL BE TEMPS AND LINGERING CLOUD COVER. MOSTLY
CLOUDY CONDITIONS OVER THE AREA ATTM KEEPING TEMPS PROPPED
UP...WITH THE EXCEPTION BEING AROUND COOPERSTOWN WHERE THE TEMPS
ARE COOLER. OTHERWISE...EXPECT TEMPS TO FOLLOW THE CURVE FOR NOW
AND ONLY MINOR ADJUSTMENTS MADE. REST OF FORECAST LOOKS ON TARGET.
AVIATION...
BAND OF THICKER MID CLOUDS FROM CENTRAL INTO SOUTHWESTERN MANITOBA
THEN INTO CNTRL ND WILL SPREAD EAST TODAY WITH LATEST RAP MODEL
INDICATING CLEARING OF THIS BAND EASTWARD TONIGHT. EAST OF THIS
THICKER CLOUD BAND...SKY COVER IS MUCH MORE VARIABLE WITH POCKETS OF
THIN MVFR STRATOCU AND A GENERALLY CLEAR SKY. EXPECT THIS AREA OF
MORE THINNER CLOUDS TO HOLD INTO THE AFTERNOON AND WILL MAKE FOR
SOME VARIABLE CEILING AREAS WITH MIXED MVFR/VFR.
&&
.PREV DISCUSSION... /ISSUED 407 AM CST FRI DEC 28 2012/
DISCUSSION...FORECAST CHALLENGE CONCERNS LINGERING -SN CHANCES AND
TEMPERATURES. MODELS OVERALL IN GOOD AGREEMENT WITH NO REAL
PREFERENCE.
MID LEVEL TROUGH FROM N CENTRAL TO SW US TO PROPAGATE GRADUALLY EAST
TODAY. A WEAK NORTHERN STREAM IMPULSE WILL CROSS FA TODAY. KMVX-88D
CONTINUES TO SHOW WEAK RETURNS ACROSS NORTHERN VALLEY REGION WITH A
VERY GRADUAL WEAKENING TREND. SURFACE METARS INDICATING VSBY ACROSS
THE REGION IN THE 3-5 MILE RANGE SO ACCUMULATING/MEASURABLE SNOWFALL
LIKELY TO BE ISOLATED. WITH TROUGH SLOWLY PROGRESSING EASTWARD AND
MOIST COLUMN WILL PROBABLY SEE SOME AREAS OF -SN/FLURRIES BUT A TOSS
UP ON WHETHER TO GO FLURRIES OR LOW POPS. ONLY MADE SOME MINOR POP
ADJUSTMENTS HOWEVER MAINTAIN MENTION OF FLURRIES OR ISOLATED SHSN.
WITH NEUTRAL THERMAL ADVECTION AND ANTICIPATED CLOUD COVER MAXIMUM
TEMPERATURES TODAY SHOULD BE PRETTY CLOSE TO WHAT HAPPENED
YESTERDAY.
HIGH PRESSURE BUILDS INTO FA TONIGHT AND THROUGH SATURDAY.
TEMPERATURES WILL HINGE GREATLY ON CLOUD TRENDS. THERE IS SOME
CLEARING WORKING ACROSS SASK AT THIS TIME AND MODELS DO INDICATE
SOME DRYING THROUGH THE COLUMN SO COULD SEE SOME CLEAR AREAS
ALLOWING TEMPERATURES TO DROP. CURRENT FORECAST REFLECTS THIS SO
WILL HOLD WITH COLDER TEMPERATURES TONIGHT. COLUMN DOES WARM
SATURDAY HOWEVER MIXING VERY LIGHT AND WITH COLDER START VALUES WILL
BE LOWER THAN PAST COUPLE DAYS.
SOME BRIEF MODERATION IN TEMPERATURES ANTICIPATED SUNDAY AS THERMAL
RIDGE SHIFTS OVER FA AHEAD OF APPROACHING COLD FRONT. ALL MODELS
INDICATING BAND OF -SN ALONG COLD FRONT SO WILL KEEP POPS ACROSS FAR
NORTH AS BOUNDARY REACHES FA BY LATE MORNING. HIGH PRESSURE QUICKLY
BUILDS IN SUNDAY NIGHT AND IF CLOUDS CLEAR OUT MINIMUMS FORECAST
COULD BE 5-10 DEGREES COLDER.
LONG TERM...MONDAY THROUGH THURSDAY.
LONG WAVE UPPER LEVEL RIDGE REMAINS OVER THE WESTERN CANADA AND LONG
WAVE TROUGH WAS OVER EASTERN CANADA/GREAT LAKES. PATTERN WILL SHIFT
SLIGHTLY EAST DURING THIS PERIOD. ECMWF UPPER AIR REMAINS THE
FASTER SOLUTION THAN THE GFS. HOWEVER THE LOW LEVEL THERMAL FIELD
THE ECMWF WAS A SLOWER SOLUTION. WILL PREFER THE SLOWER ECMWF.
HIGH TEMPS WERE LOWERED A DEGREE OR TWO FOR MON AND TUE. LOWERED
TEMPS STRONGER FOR WED AND THU BY 5 TO 10 DEGREES.
ADDED CHANCE FOR LIGHT SNOW IN THE NORTHEAST ZONES TUE NIGHT.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
HOPKINS
AREA FORECAST DISCUSSION
NWS TULSA OK
1133 AM CST FRI DEC 28 2012
.AVIATION...
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM.
BAND OF LIGHT SNOW MOVING FROM CENTRAL OK INTO EASTERN OK. THIS IS
IN RESPONSE TO AN UPPER LEVEL TROUGH MOVING RAPIDLY THROUGH THE
SOUTHERN PLAINS. EXPECT THIS SNOW TO MOVE EAST ABOUT 20-25KT AND
GRADUALLY WEAKEN AND THE UPPER LEVEL SHIFTS INTO AR BY ABOUT 00Z.
IFR CONDITIONS PROBABLE WHERE SNOW IS OCCURRING. RAPID CLEARING
EXPECTED BEHIND THE TROUGH...WHICH IS EVIDENT IN VISIBLE SATELLITE
IMAGES OVER WESTERN OK AT THIS TIME. /SA
&&
.PREV DISCUSSION... /ISSUED 907 AM CST FRI DEC 28 2012/
DISCUSSION...
THE BULK OF THE WARM CONVEYOR PRECIP IN ADVANCE OF AN APPROACHING
UPPER TROUGH HAS SHIFTED EAST OF THE FORECAST AREA INTO ARKANSAS.
A WELL DEFINED PV MAX WAS EVIDENT ON WV IMAGERY OVER WESTERN
OK...AND A BAND OF SNOW HAS DEVELOPED OVER CENTRAL OK MOVING
EAST. I HAVE INSERTED SOME AFTERNOON POPS INTO THE FORECAST FOR
SNOW AND WILL ADJUST THE FORECAST AS NEEDED LATER TO SEE HOW
THINGS EVOLVE. THE LATEST HRRR HAS ANOTHER BAND DEVELOPING OVER
FAR EASTERN OK OR FAR WESTERN AR THIS AFTERNOON AS WELL.
LACY
.PRELIMINARY POINT TEMPS/POPS...
TUL 34 16 40 21 / 70 0 0 0
FSM 39 23 38 21 / 20 0 0 0
MLC 37 18 39 19 / 50 0 0 10
BVO 34 14 41 13 / 30 0 0 0
FYV 36 17 35 15 / 20 0 0 0
BYV 35 19 35 20 / 20 0 0 0
MKO 36 16 38 19 / 70 0 0 10
MIO 35 16 36 18 / 60 0 0 0
F10 36 17 39 20 / 60 0 0 10
HHW 37 21 40 22 / 10 0 0 10
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...WINTER WEATHER ADVISORY UNTIL 6 PM FRIDAY FOR OKZ054-OKZ055-
OKZ056-OKZ057-OKZ058-OKZ059-OKZ060-OKZ061-OKZ062-OKZ063-
OKZ064-OKZ065-OKZ066-OKZ067-OKZ068-OKZ069-OKZ070-OKZ071-
OKZ072-OKZ073-OKZ074-OKZ075.
AR...NONE.
&&
$$
SHORT TERM...30
LONG TERM....10
AVIATION...02
AREA FORECAST DISCUSSION
NWS TULSA OK
907 AM CST FRI DEC 28 2012
.DISCUSSION...
THE BULK OF THE WARM CONVEYOR PRECIP IN ADVANCE OF AN APPROACHING
UPPER TROUGH HAS SHIFTED EAST OF THE FORECAST AREA INTO ARKANSAS.
A WELL DEFINED PV MAX WAS EVIDENT ON WV IMAGERY OVER WESTERN
OK...AND A BAND OF SNOW HAS DEVELOPED OVER CENTRAL OK MOVING
EAST. I HAVE INSERTED SOME AFTERNOON POPS INTO THE FORECAST FOR
SNOW AND WILL ADJUST THE FORECAST AS NEEDED LATER TO SEE HOW
THINGS EVOLVE. THE LATEST HRRR HAS ANOTHER BAND DEVELOPING OVER
FAR EASTERN OK OR FAR WESTERN AR THIS AFTERNOON AS WELL.
LACY
&&
.PREV DISCUSSION... /ISSUED 530 AM CST FRI DEC 28 2012/
AVIATION...
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM.
IFR TO LIFR CONDITIONS IN DRIZZLE AND FOG WILL AFFECT SOUTHEAST
OKLAHOMA AND NORTHWEST ARKANSAS SITES THIS MORNING...WITH MAINLY
MVFR CEILINGS AT THE NORTHEAST OKLAHOMA SITES. CONDITIONS WILL
IMPROVE BY AFTERNOON...WITH VFR RETURNING TO THE NORTHEAST
OKLAHOMA SITES AT THAT TIME...TO KMLC BY THIS EVENING...AND TO THE
NORTHWEST ARKANSAS SITES BY LATE TONIGHT.
PREV DISCUSSION... /ISSUED 407 AM CST FRI DEC 28 2012/
DISCUSSION...
WEAK UPPER LEVEL SYSTEM CURRENTLY OVER TX/OK PANHANDLE REGION
CONTINUES TO PROVIDE JUST ENOUGH LIFT FROM SE OKLAHOMA INTO WEST
CENTRAL ARKANSAS FOR SCATTERED VERY LIGHT RAIN MAINLY SOUTH OF
I-40 THIS MORNING. SFC TEMPS MOSTLY AT OR SLIGHTLY ABOVE FREEZING
BUT HAVE SEEN A FEW REPORTS OF FREEZING DRIZZLE AND EXPECT THAT
MAINLY ELEVATED ROADWAYS WILL CONTINUE TO BE IMPACTED THROUGH THE
MORNING. WILL LEAVE THE FREEZING RAIN ADVISORY IN TACT THROUGH 8
AM...REST OF AREA COULD SEE A LITTLE FREEZING DRIZZLE OR FREEZING
FOR THIS MORNING...AND A FEW FLURRIES NOT EVEN OUT OF THE QUESTION
AS THE SYSTEM MOVES OVER THE AREA LATER TODAY. ASSOCIATED COLD
FRONT WILL PUSH THROUGH AND WILL BRING DRIER LOW LEVEL AIR IN AND
HELP SHUT OFF DRIZZLE THIS AFTERNOON.
CLEARING SKIES AND COLDER TONIGHT WITH A SLOW WARM UP THROUGH THE
WEEKEND AHEAD OF THE NEXT APPROACHING SYSTEM...DUE TO BRING
PRIMARILY A RAIN EVENT FOR SUNDAY NIGHT AND NEW YEARS EVE. A
LITTLE CONCERNED THAT SHALLOW COLD AIR MAY REMAIN ENTRENCHED IN
SOME NW ARKANSAS VALLEYS JUST ENOUGH FOR POCKETS OF LIGHT FREEZING
RAIN INTO EARLY MON MORNING. COOLER AIR MOVING IN BEHIND THE
SYSTEM MAY ALLOW FOR A CHANGEOVER TO SLEET OR SNOW IN NORTHERN
AREAS NEW YEARS DAY...ALTHOUGH MOST MODELS SUGGEST THAT MAIN UPPER
ENERGY WILL BE NORTH BY THAT TIME.
&&
.PRELIMINARY POINT TEMPS/POPS...
TUL 37 17 41 23 / 20 0 0 0
FSM 40 24 40 23 / 30 0 0 0
MLC 37 18 40 19 / 20 0 0 10
BVO 36 14 42 13 / 10 0 0 0
FYV 35 17 37 15 / 30 0 0 0
BYV 35 20 35 21 / 30 0 0 0
MKO 37 17 38 19 / 20 0 0 10
MIO 35 18 37 19 / 20 0 0 0
F10 36 17 40 20 / 20 0 0 10
HHW 40 21 41 22 / 20 0 0 10
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...FREEZING RAIN ADVISORY UNTIL 10 AM FRIDAY FOR OKZ072-OKZ074-
OKZ075-OKZ076.
AR...FREEZING RAIN ADVISORY UNTIL 10 AM FRIDAY FOR ARZ019-ARZ020-
ARZ029.
&&
$$
LONG TERM....30
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
1148 AM CST FRI DEC 28 2012
.UPDATE...ADDED AVIATION SECTION FOR 18Z TAF`S.
&&
.AVIATION...BNA/CKV/CSV...MORNING RA/IP HAS FOR THE MOST PART
DISSIPATED, LEAVING MIDDLE TN WITH VFR CIGS AND GRADUALLY
INCREASING WINDS. MUCH LARGER AREA OF LIGHT TO MODERATE RAIN IS
MOVING INTO THE MID STATE AND WILL AFFECT US MUCH OF THE
AFTERNOON. EXPECTING COLD FROPA DURING THE LATE EVENING AS THE
SURFACE LOW TRACK BISECTS MIDDLE TENNESSEE. PROBABLY WON`T SEE ANY
FROZEN PRECIP UNTIL AFTER FROPA, BUT BY THEN THE MOISTURE WILL
HAVE THINNED OUT AND WE`LL BE LEFT WITH LIGHT RA/SN DURING THE
OVERNIGHT PERIOD. LOOK FOR WINDS TO PICK UP TOWARD MORNING AS THE
SURFACE PRESSURE GRADIENT INCREASES. THERE SHOULD BE ENOUGH LOW-
LEVEL MOISTURE PRESENT AFTER 12Z TO KEEP LOW CLOUDS IN AND SQUEEZE
OUT SOME COLD ADVECTION FLURRIES, BUT NOT EXPECTING ANY
ACCUMULATION.
&&
.PREV DISCUSSION... /ISSUED 747 AM CST FRI DEC 28 2012/
DISCUSSION...
LATEST RADAR IMAGERY AND NUMEROUS REPORTS INDICATE A WIDESPREAD
RAIN/SLEET MIX HAS OVERSPREAD THE SOUTHWESTERN PORTIONS OF MIDDLE
TENNESSEE. SO FAR NO SIGNIFICANT ACCUMULATION HAS BEEN
REPORTED...AND SURFACE OBSERVATIONS INDICATE TEMPERATURES ARE NOW
AT OR ABOVE FREEZING FOR NEARLY ALL LOCATIONS. THUS A CHANGEOVER
TO ALL RAIN IS STILL EXPECTED IN THE NEXT COUPLE OF HOURS AS
TEMPERATURES/DEWPOINTS CONTINUE TO WARM. HAVE UPDATED FORECAST FOR
THIS MORNING TO REMOVE MENTION OF FZRA AS PRECIP SHOULD BE
PREDOMINATELY RAIN/SLEET. IN ADDITION...06Z GUIDANCE CONTINUES
TREND FROM 00Z MODELS WITH LIGHT SNOW ACCUMULATIONS OVER NORTHWEST
ZONES LATE FRIDAY EVENING INTO FRIDAY NIGHT AS CAA INCREASES AND
TEMPERATURES FALL BACK TO NEAR FREEZING. ADJUSTED POPS/WX GRIDS
ACCORDINGLY AND RAISED TOTAL SNOW ACCUMS IN THIS AREA INTO THE
0.5-1.0 INCH RANGE. WILL LET DAY SHIFT ANALYZE THE 12Z GUIDANCE TO
SEE IF A WINTER WX ADVISORY WILL BE NECESSARY FOR THE NORTHWEST
ZONES FRIDAY NIGHT. REST OF FORECAST REMAINS UNCHANGED.
PREV DISCUSSION... /ISSUED 428 AM CST FRI DEC 28 2012/
UPDATE...FOR 12Z TAFS
AVIATION...12Z TAFS
RADAR DEPICTS LIGHT RETURNS BEGINNING TO OVERSPREAD WEST TN. THE
PRECIP IS INITIALLY FALLING OUT OF A MID LVL CLOUD DECK AND IS
FALLING THROUGH VERY DRY AIR. THIS MEANS CEILINGS WILL BE SLOW TO
DROP AND WE WILL NOT SEE MUCH OF A VSBY RESTRICTION FOR AWHILE
AFTER THE RAIN STARTS LATER THIS MORNING. THE AFOREMENTIONED DRY
LAYER WILL ALSO ALLOW SOME SLEET TO FORM AND WE ARE FORECASTING A
MIX OF RAIN AND SLEET AT ALL THE TAF SITES AT THE ONSET.
CIGS AND VSBY WILL GRADUAL DECREASE LATER TODAY BECOMING MAINLY
IFR BY THIS EVENING. COLDER AIR WRAPPING IN AFTER 06Z WILL ALLOW
THE RAIN TO TURN TO SNOW WITH THE BEST CHC FOR SIGNIFICANT VSBY
RESTRICTION AT CKV.
PREV DISCUSSION... /ISSUED 331 AM CST FRI DEC 28 2012/
SHORT TERM...
SOMEWHAT DIFFICULT FORECAST FOR TODAY AND TOMORROW WITH LIKELY
WINTER PRECIPITATION AND ANY ACCUMULATIONS THAT MAY OCCUR. LATEST
RADAR IMAGERY SHOWS EXTENSIVE AREA OF RAIN HAS DEVELOPED OVER THE
LOWER MISSISSIPPI VALLEY AND HAS SPREAD NORTHEAST INTO WEST
TENNESSEE. LATEST HRRR RUNS INDICATE THIS PRECIPITATION WILL ENTER
THE FORECAST AREA BETWEEN 11-12Z. SURFACE OBSERVATIONS SHOW
TEMPERATURES ARE CURRENTLY IN THE UPPER 20S TO LOWER 30S WITH
DEWPOINTS IN THE 20S...AND THERMODYNAMIC PROFILES INDICATE PRECIP
WILL BEGIN AS A MIX OF RAIN WITH LIGHT SLEET AND POSSIBLY LIGHT
FREEZING RAIN DUE TO THE VERY DRY LOWER TROPOSPHERE. NO SLEET OR
ICE ACCUMULATION IS CURRENTLY ANTICIPATED DUE TO THE BRIEF PERIOD
OF MIXED PRECIPITATION AND EXPECTED STRENGTHENING WAA...BUT WILL
CONTINUE TO CLOSELY MONITOR...PARTICULARLY SOUTHWEST ZONES WHERE
SKIES CLEARED EARLIER AND TEMPERATURES ARE NOW BELOW FREEZING. BY
LATE MORNING ALL PRECIP WILL BECOME RAIN AS WAA CONTINUES TO
INCREASE AND ADVECTS WARMER TEMPS AT THE SURFACE AND ALOFT INTO
THE AREA. HAVE RAISED POPS TO CATEGORICAL AREAWIDE BASED ON LATEST
MOS GUIDANCE AND RADAR TRENDS...AND KEPT TEMPS NEAR MOS AS WELL.
WINTER PRECIP AGAIN BECOMES AN ISSUE LATE THIS EVENING AND
TONIGHT AS CAA BEGINS OVER NORTHWEST ZONES ON BACKSIDE OF SYSTEM.
BUFKIT FORECAST SOUNDINGS INDICATE PROFILES BECOME FAVORABLE FOR
SNOW TO MIX WITH THE RAIN LATE THIS EVENING FOR FAR NORTHWEST
ZONES WITH A CHANGEOVER TO ALL SNOW BY SATURDAY MORNING PRIOR TO
BULK OF PRECIP COMING TO AN END. ALL GUIDANCE AND HPC
PROBABILITIES INDICATE SOME LIGHT SNOW ACCUMULATIONS GENERALLY
ALONG AND NORTH OF A LINE FROM BENTON TO CLARKSVILLE...AND HAVE
MENTIONED UP TO A HALF INCH OF SNOW ACCUMS POSSIBLE IN THIS AREA
FOR FRIDAY NIGHT. SHOULD SNOW ACCUMS OCCUR...THERE WOULD MAINLY
BE ON ELEVATED SURFACES AND GRASSY AREAS DUE TO THE WET NATURE OF
THE SNOW...AND NEED FOR AN ADVISORY IS NOT CURRENTLY ANTICIPATED.
AS CAA CONTINUES ON SATURDAY...THERMO PROFILES BECOME FAVORABLE
FOR LIGHT SNOW AND FLURRIES ACROSS THE ENTIRE CWA. CANNOT RULE OUT
A DUSTING OF SNOW IN SOME AREAS...MAINLY HIGHER ELEVATIONS AND
ESPECIALLY THE PLATEAU WHERE UPSLOPE WILL BE FAVORABLE.
LONG TERM...
AFTER ONE DRY DAY EXPECTED FOR SUNDAY...NEXT STORM SYSTEM ENTERS
THE PICTURE ON MONDAY. GLOBAL MODELS DIFFER SOMEWHAT ON TIMING
AND DETAILS WITH THIS EVENT...BUT GENERALLY INDICATE PRECIP WILL
ONCE AGAIN SPREAD INTO THE CWA FROM THE SOUTHWEST AND FALL INTO
INITIALLY COLD AND DRY LOWER LEVELS. FORECAST SOUNDINGS SUGGEST A
LIGHT WINTRY MIX IS POSSIBLE MONDAY MORNING BEFORE A CHANGEOVER
TO ALL RAIN...WITH RAIN CONTINUING INTO NEW YEARS DAY. AS WITH THE
PREVIOUS SYSTEM...CAA ON BACKSIDE MAY ALLOW FOR A CHANGEOVER TO A
RAIN/SNOW MIX PRIOR TO PRECIP ENDING TUESDAY NIGHT. DOES NOT
CURRENTLY APPEAR ANY SIGNIFICANT ACCUMULATIONS OF WINTRY
PRECIPITATION WILL OCCUR IN OUR FORECAST AREA WITH THIS SYSTEM
DUE TO COLDER AIR LOCATED FURTHER NORTH. HAVE KEPT REST OF LONG
TERM FORECAST COLD AND DRY AS WE MOVE THROUGH THE FIRST WEEK OF
2013...BUT ACTIVE SOUTHERN JET STREAM INDICATED ON GLOBAL MODELS
SUGGEST FREQUENT STORM SYSTEMS WILL AFFECT THE MID STATE OVER THE
FIRST PART OF JANUARY.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
ROSE
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
747 AM CST FRI DEC 28 2012
.DISCUSSION...
LATEST RADAR IMAGERY AND NUMEROUS REPORTS INDICATE A WIDESPREAD
RAIN/SLEET MIX HAS OVERSPREAD THE SOUTHWESTERN PORTIONS OF MIDDLE
TENNESSEE. SO FAR NO SIGNIFICANT ACCUMULATION HAS BEEN
REPORTED...AND SURFACE OBSERVATIONS INDICATE TEMPERATURES ARE NOW
AT OR ABOVE FREEZING FOR NEARLY ALL LOCATIONS. THUS A CHANGEOVER
TO ALL RAIN IS STILL EXPECTED IN THE NEXT COUPLE OF HOURS AS
TEMPERATURES/DEWPOINTS CONTINUE TO WARM. HAVE UPDATED FORECAST FOR
THIS MORNING TO REMOVE MENTION OF FZRA AS PRECIP SHOULD BE
PREDOMINATELY RAIN/SLEET. IN ADDITION...06Z GUIDANCE CONTINUES
TREND FROM 00Z MODELS WITH LIGHT SNOW ACCUMULATIONS OVER NORTHWEST
ZONES LATE FRIDAY EVENING INTO FRIDAY NIGHT AS CAA INCREASES AND
TEMPERATURES FALL BACK TO NEAR FREEZING. ADJUSTED POPS/WX GRIDS
ACCORDINGLY AND RAISED TOTAL SNOW ACCUMS IN THIS AREA INTO THE
0.5-1.0 INCH RANGE. WILL LET DAY SHIFT ANALYZE THE 12Z GUIDANCE TO
SEE IF A WINTER WX ADVISORY WILL BE NECESSARY FOR THE NORTHWEST
ZONES FRIDAY NIGHT. REST OF FORECAST REMAINS UNCHANGED.
&&
.PREV DISCUSSION... /ISSUED 428 AM CST FRI DEC 28 2012/
UPDATE...FOR 12Z TAFS
AVIATION...12Z TAFS
RADAR DEPICTS LIGHT RETURNS BEGINNING TO OVERSPREAD WEST TN. THE
PRECIP IS INITIALLY FALLING OUT OF A MID LVL CLOUD DECK AND IS
FALLING THROUGH VERY DRY AIR. THIS MEANS CEILINGS WILL BE SLOW TO
DROP AND WE WILL NOT SEE MUCH OF A VSBY RESTRICTION FOR AWHILE
AFTER THE RAIN STARTS LATER THIS MORNING. THE AFOREMENTIONED DRY
LAYER WILL ALSO ALLOW SOME SLEET TO FORM AND WE ARE FORECASTING A
MIX OF RAIN AND SLEET AT ALL THE TAF SITES AT THE ONSET.
CIGS AND VSBY WILL GRADUAL DECREASE LATER TODAY BECOMING MAINLY
IFR BY THIS EVENING. COLDER AIR WRAPPING IN AFTER 06Z WILL ALLOW
THE RAIN TO TURN TO SNOW WITH THE BEST CHC FOR SIGNIFICANT VSBY
RESTRICTION AT CKV.
PREV DISCUSSION... /ISSUED 331 AM CST FRI DEC 28 2012/
SHORT TERM...
SOMEWHAT DIFFICULT FORECAST FOR TODAY AND TOMORROW WITH LIKELY
WINTER PRECIPITATION AND ANY ACCUMULATIONS THAT MAY OCCUR. LATEST
RADAR IMAGERY SHOWS EXTENSIVE AREA OF RAIN HAS DEVELOPED OVER THE
LOWER MISSISSIPPI VALLEY AND HAS SPREAD NORTHEAST INTO WEST
TENNESSEE. LATEST HRRR RUNS INDICATE THIS PRECIPITATION WILL ENTER
THE FORECAST AREA BETWEEN 11-12Z. SURFACE OBSERVATIONS SHOW
TEMPERATURES ARE CURRENTLY IN THE UPPER 20S TO LOWER 30S WITH
DEWPOINTS IN THE 20S...AND THERMODYNAMIC PROFILES INDICATE PRECIP
WILL BEGIN AS A MIX OF RAIN WITH LIGHT SLEET AND POSSIBLY LIGHT
FREEZING RAIN DUE TO THE VERY DRY LOWER TROPOSPHERE. NO SLEET OR
ICE ACCUMULATION IS CURRENTLY ANTICIPATED DUE TO THE BRIEF PERIOD
OF MIXED PRECIPITATION AND EXPECTED STRENGTHENING WAA...BUT WILL
CONTINUE TO CLOSELY MONITOR...PARTICULARLY SOUTHWEST ZONES WHERE
SKIES CLEARED EARLIER AND TEMPERATURES ARE NOW BELOW FREEZING. BY
LATE MORNING ALL PRECIP WILL BECOME RAIN AS WAA CONTINUES TO
INCREASE AND ADVECTS WARMER TEMPS AT THE SURFACE AND ALOFT INTO
THE AREA. HAVE RAISED POPS TO CATEGORICAL AREAWIDE BASED ON LATEST
MOS GUIDANCE AND RADAR TRENDS...AND KEPT TEMPS NEAR MOS AS WELL.
WINTER PRECIP AGAIN BECOMES AN ISSUE LATE THIS EVENING AND
TONIGHT AS CAA BEGINS OVER NORTHWEST ZONES ON BACKSIDE OF SYSTEM.
BUFKIT FORECAST SOUNDINGS INDICATE PROFILES BECOME FAVORABLE FOR
SNOW TO MIX WITH THE RAIN LATE THIS EVENING FOR FAR NORTHWEST
ZONES WITH A CHANGEOVER TO ALL SNOW BY SATURDAY MORNING PRIOR TO
BULK OF PRECIP COMING TO AN END. ALL GUIDANCE AND HPC
PROBABILITIES INDICATE SOME LIGHT SNOW ACCUMULATIONS GENERALLY
ALONG AND NORTH OF A LINE FROM BENTON TO CLARKSVILLE...AND HAVE
MENTIONED UP TO A HALF INCH OF SNOW ACCUMS POSSIBLE IN THIS AREA
FOR FRIDAY NIGHT. SHOULD SNOW ACCUMS OCCUR...THERE WOULD MAINLY
BE ON ELEVATED SURFACES AND GRASSY AREAS DUE TO THE WET NATURE OF
THE SNOW...AND NEED FOR AN ADVISORY IS NOT CURRENTLY ANTICIPATED.
AS CAA CONTINUES ON SATURDAY...THERMO PROFILES BECOME FAVORABLE
FOR LIGHT SNOW AND FLURRIES ACROSS THE ENTIRE CWA. CANNOT RULE OUT
A DUSTING OF SNOW IN SOME AREAS...MAINLY HIGHER ELEVATIONS AND
ESPECIALLY THE PLATEAU WHERE UPSLOPE WILL BE FAVORABLE.
LONG TERM...
AFTER ONE DRY DAY EXPECTED FOR SUNDAY...NEXT STORM SYSTEM ENTERS
THE PICTURE ON MONDAY. GLOBAL MODELS DIFFER SOMEWHAT ON TIMING
AND DETAILS WITH THIS EVENT...BUT GENERALLY INDICATE PRECIP WILL
ONCE AGAIN SPREAD INTO THE CWA FROM THE SOUTHWEST AND FALL INTO
INITIALLY COLD AND DRY LOWER LEVELS. FORECAST SOUNDINGS SUGGEST A
LIGHT WINTRY MIX IS POSSIBLE MONDAY MORNING BEFORE A CHANGEOVER
TO ALL RAIN...WITH RAIN CONTINUING INTO NEW YEARS DAY. AS WITH THE
PREVIOUS SYSTEM...CAA ON BACKSIDE MAY ALLOW FOR A CHANGEOVER TO A
RAIN/SNOW MIX PRIOR TO PRECIP ENDING TUESDAY NIGHT. DOES NOT
CURRENTLY APPEAR ANY SIGNIFICANT ACCUMULATIONS OF WINTRY
PRECIPITATION WILL OCCUR IN OUR FORECAST AREA WITH THIS SYSTEM
DUE TO COLDER AIR LOCATED FURTHER NORTH. HAVE KEPT REST OF LONG
TERM FORECAST COLD AND DRY AS WE MOVE THROUGH THE FIRST WEEK OF
2013...BUT ACTIVE SOUTHERN JET STREAM INDICATED ON GLOBAL MODELS
SUGGEST FREQUENT STORM SYSTEMS WILL AFFECT THE MID STATE OVER THE
FIRST PART OF JANUARY.
&&
.PRELIMINARY POINT TEMPS/POPS...
NASHVILLE 42 33 35 24 / 90 100 30 05
CLARKSVILLE 39 30 34 22 / 90 100 20 05
CROSSVILLE 45 34 34 22 / 70 100 30 20
COLUMBIA 43 33 36 24 / 100 90 20 05
LAWRENCEBURG 44 33 36 24 / 100 90 20 05
WAVERLY 39 30 34 22 / 100 90 20 05
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHAMBURGER
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
428 AM CST FRI DEC 28 2012
.UPDATE...FOR 12Z TAFS
&&
.AVIATION...12Z TAFS
RADAR DEPICTS LIGHT RETURNS BEGINNING TO OVERSPREAD WEST TN. THE
PRECIP IS INITIALLY FALLING OUT OF A MID LVL CLOUD DECK AND IS
FALLING THROUGH VERY DRY AIR. THIS MEANS CEILINGS WILL BE SLOW TO
DROP AND WE WILL NOT SEE MUCH OF A VSBY RESTRICTION FOR AWHILE
AFTER THE RAIN STARTS LATER THIS MORNING. THE AFOREMENTIONED DRY
LAYER WILL ALSO ALLOW SOME SLEET TO FORM AND WE ARE FORECASTING A
MIX OF RAIN AND SLEET AT ALL THE TAF SITES AT THE ONSET.
CIGS AND VSBY WILL GRADUAL DECREASE LATER TODAY BECOMING MAINLY
IFR BY THIS EVENING. COLDER AIR WRAPPING IN AFTER 06Z WILL ALLOW
THE RAIN TO TURN TO SNOW WITH THE BEST CHC FOR SIGNIFICANT VSBY
RESTRICTION AT CKV.
&&
.PREV DISCUSSION... /ISSUED 331 AM CST FRI DEC 28 2012/
SHORT TERM...
SOMEWHAT DIFFICULT FORECAST FOR TODAY AND TOMORROW WITH LIKELY
WINTER PRECIPITATION AND ANY ACCUMULATIONS THAT MAY OCCUR. LATEST
RADAR IMAGERY SHOWS EXTENSIVE AREA OF RAIN HAS DEVELOPED OVER THE
LOWER MISSISSIPPI VALLEY AND HAS SPREAD NORTHEAST INTO WEST
TENNESSEE. LATEST HRRR RUNS INDICATE THIS PRECIPITATION WILL ENTER
THE FORECAST AREA BETWEEN 11-12Z. SURFACE OBSERVATIONS SHOW
TEMPERATURES ARE CURRENTLY IN THE UPPER 20S TO LOWER 30S WITH
DEWPOINTS IN THE 20S...AND THERMODYNAMIC PROFILES INDICATE PRECIP
WILL BEGIN AS A MIX OF RAIN WITH LIGHT SLEET AND POSSIBLY LIGHT
FREEZING RAIN DUE TO THE VERY DRY LOWER TROPOSPHERE. NO SLEET OR
ICE ACCUMULATION IS CURRENTLY ANTICIPATED DUE TO THE BRIEF PERIOD
OF MIXED PRECIPITATION AND EXPECTED STRENGTHENING WAA...BUT WILL
CONTINUE TO CLOSELY MONITOR...PARTICULARLY SOUTHWEST ZONES WHERE
SKIES CLEARED EARLIER AND TEMPERATURES ARE NOW BELOW FREEZING. BY
LATE MORNING ALL PRECIP WILL BECOME RAIN AS WAA CONTINUES TO
INCREASE AND ADVECTS WARMER TEMPS AT THE SURFACE AND ALOFT INTO
THE AREA. HAVE RAISED POPS TO CATEGORICAL AREAWIDE BASED ON LATEST
MOS GUIDANCE AND RADAR TRENDS...AND KEPT TEMPS NEAR MOS AS WELL.
WINTER PRECIP AGAIN BECOMES AN ISSUE LATE THIS EVENING AND
TONIGHT AS CAA BEGINS OVER NORTHWEST ZONES ON BACKSIDE OF SYSTEM.
BUFKIT FORECAST SOUNDINGS INDICATE PROFILES BECOME FAVORABLE FOR
SNOW TO MIX WITH THE RAIN LATE THIS EVENING FOR FAR NORTHWEST
ZONES WITH A CHANGEOVER TO ALL SNOW BY SATURDAY MORNING PRIOR TO
BULK OF PRECIP COMING TO AN END. ALL GUIDANCE AND HPC
PROBABILITIES INDICATE SOME LIGHT SNOW ACCUMULATIONS GENERALLY
ALONG AND NORTH OF A LINE FROM BENTON TO CLARKSVILLE...AND HAVE
MENTIONED UP TO A HALF INCH OF SNOW ACCUMS POSSIBLE IN THIS AREA
FOR FRIDAY NIGHT. SHOULD SNOW ACCUMS OCCUR...THERE WOULD MAINLY
BE ON ELEVATED SURFACES AND GRASSY AREAS DUE TO THE WET NATURE OF
THE SNOW...AND NEED FOR AN ADVISORY IS NOT CURRENTLY ANTICIPATED.
AS CAA CONTINUES ON SATURDAY...THERMO PROFILES BECOME FAVORABLE
FOR LIGHT SNOW AND FLURRIES ACROSS THE ENTIRE CWA. CANNOT RULE OUT
A DUSTING OF SNOW IN SOME AREAS...MAINLY HIGHER ELEVATIONS AND
ESPECIALLY THE PLATEAU WHERE UPSLOPE WILL BE FAVORABLE.
LONG TERM...
AFTER ONE DRY DAY EXPECTED FOR SUNDAY...NEXT STORM SYSTEM ENTERS
THE PICTURE ON MONDAY. GLOBAL MODELS DIFFER SOMEWHAT ON TIMING
AND DETAILS WITH THIS EVENT...BUT GENERALLY INDICATE PRECIP WILL
ONCE AGAIN SPREAD INTO THE CWA FROM THE SOUTHWEST AND FALL INTO
INITIALLY COLD AND DRY LOWER LEVELS. FORECAST SOUNDINGS SUGGEST A
LIGHT WINTRY MIX IS POSSIBLE MONDAY MORNING BEFORE A CHANGEOVER
TO ALL RAIN...WITH RAIN CONTINUING INTO NEW YEARS DAY. AS WITH THE
PREVIOUS SYSTEM...CAA ON BACKSIDE MAY ALLOW FOR A CHANGEOVER TO A
RAIN/SNOW MIX PRIOR TO PRECIP ENDING TUESDAY NIGHT. DOES NOT
CURRENTLY APPEAR ANY SIGNIFICANT ACCUMULATIONS OF WINTRY
PRECIPITATION WILL OCCUR IN OUR FORECAST AREA WITH THIS SYSTEM
DUE TO COLDER AIR LOCATED FURTHER NORTH. HAVE KEPT REST OF LONG
TERM FORECAST COLD AND DRY AS WE MOVE THROUGH THE FIRST WEEK OF
2013...BUT ACTIVE SOUTHERN JET STREAM INDICATED ON GLOBAL MODELS
SUGGEST FREQUENT STORM SYSTEMS WILL AFFECT THE MID STATE OVER THE
FIRST PART OF JANUARY.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
99
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
331 AM CST FRI DEC 28 2012
.SHORT TERM...
SOMEWHAT DIFFICULT FORECAST FOR TODAY AND TOMORROW WITH LIKELY
WINTER PRECIPITATION AND ANY ACCUMULATIONS THAT MAY OCCUR. LATEST
RADAR IMAGERY SHOWS EXTENSIVE AREA OF RAIN HAS DEVELOPED OVER THE
LOWER MISSISSIPPI VALLEY AND HAS SPREAD NORTHEAST INTO WEST
TENNESSEE. LATEST HRRR RUNS INDICATE THIS PRECIPITATION WILL ENTER
THE FORECAST AREA BETWEEN 11-12Z. SURFACE OBSERVATIONS SHOW
TEMPERATURES ARE CURRENTLY IN THE UPPER 20S TO LOWER 30S WITH
DEWPOINTS IN THE 20S...AND THERMODYNAMIC PROFILES INDICATE PRECIP
WILL BEGIN AS A MIX OF RAIN WITH LIGHT SLEET AND POSSIBLY LIGHT
FREEZING RAIN DUE TO THE VERY DRY LOWER TROPOSPHERE. NO SLEET OR
ICE ACCUMULATION IS CURRENTLY ANTICIPATED DUE TO THE BRIEF PERIOD
OF MIXED PRECIPITATION AND EXPECTED STRENGTHENING WAA...BUT WILL
CONTINUE TO CLOSELY MONITOR...PARTICULARLY SOUTHWEST ZONES WHERE
SKIES CLEARED EARLIER AND TEMPERATURES ARE NOW BELOW FREEZING. BY
LATE MORNING ALL PRECIP WILL BECOME RAIN AS WAA CONTINUES TO
INCREASE AND ADVECTS WARMER TEMPS AT THE SURFACE AND ALOFT INTO
THE AREA. HAVE RAISED POPS TO CATEGORICAL AREAWIDE BASED ON LATEST
MOS GUIDANCE AND RADAR TRENDS...AND KEPT TEMPS NEAR MOS AS WELL.
WINTER PRECIP AGAIN BECOMES AN ISSUE LATE THIS EVENING AND
TONIGHT AS CAA BEGINS OVER NORTHWEST ZONES ON BACKSIDE OF SYSTEM.
BUFKIT FORECAST SOUNDINGS INDICATE PROFILES BECOME FAVORABLE FOR
SNOW TO MIX WITH THE RAIN LATE THIS EVENING FOR FAR NORTHWEST
ZONES WITH A CHANGEOVER TO ALL SNOW BY SATURDAY MORNING PRIOR TO
BULK OF PRECIP COMING TO AN END. ALL GUIDANCE AND HPC
PROBABILITIES INDICATE SOME LIGHT SNOW ACCUMULATIONS GENERALLY
ALONG AND NORTH OF A LINE FROM BENTON TO CLARKSVILLE...AND HAVE
MENTIONED UP TO A HALF INCH OF SNOW ACCUMS POSSIBLE IN THIS AREA
FOR FRIDAY NIGHT. SHOULD SNOW ACCUMS OCCUR...THERE WOULD MAINLY
BE ON ELEVATED SURFACES AND GRASSY AREAS DUE TO THE WET NATURE OF
THE SNOW...AND NEED FOR AN ADVISORY IS NOT CURRENTLY ANTICIPATED.
AS CAA CONTINUES ON SATURDAY...THERMO PROFILES BECOME FAVORABLE
FOR LIGHT SNOW AND FLURRIES ACROSS THE ENTIRE CWA. CANNOT RULE OUT
A DUSTING OF SNOW IN SOME AREAS...MAINLY HIGHER ELEVATIONS AND
ESPECIALLY THE PLATEAU WHERE UPSLOPE WILL BE FAVORABLE.
.LONG TERM...
AFTER ONE DRY DAY EXPECTED FOR SUNDAY...NEXT STORM SYSTEM ENTERS
THE PICTURE ON MONDAY. GLOBAL MODELS DIFFER SOMEWHAT ON TIMING
AND DETAILS WITH THIS EVENT...BUT GENERALLY INDICATE PRECIP WILL
ONCE AGAIN SPREAD INTO THE CWA FROM THE SOUTHWEST AND FALL INTO
INITIALLY COLD AND DRY LOWER LEVELS. FORECAST SOUNDINGS SUGGEST A
LIGHT WINTRY MIX IS POSSIBLE MONDAY MORNING BEFORE A CHANGEOVER
TO ALL RAIN...WITH RAIN CONTINUING INTO NEW YEARS DAY. AS WITH THE
PREVIOUS SYSTEM...CAA ON BACKSIDE MAY ALLOW FOR A CHANGEOVER TO A
RAIN/SNOW MIX PRIOR TO PRECIP ENDING TUESDAY NIGHT. DOES NOT
CURRENTLY APPEAR ANY SIGNIFICANT ACCUMULATIONS OF WINTRY
PRECIPITATION WILL OCCUR IN OUR FORECAST AREA WITH THIS SYSTEM
DUE TO COLDER AIR LOCATED FURTHER NORTH. HAVE KEPT REST OF LONG
TERM FORECAST COLD AND DRY AS WE MOVE THROUGH THE FIRST WEEK OF
2013...BUT ACTIVE SOUTHERN JET STREAM INDICATED ON GLOBAL MODELS
SUGGEST FREQUENT STORM SYSTEMS WILL AFFECT THE MID STATE OVER THE
FIRST PART OF JANUARY.
&&
.PRELIMINARY POINT TEMPS/POPS...
NASHVILLE 42 33 35 24 / 90 100 30 05
CLARKSVILLE 39 30 34 22 / 90 100 20 05
CROSSVILLE 45 34 34 22 / 70 100 30 20
COLUMBIA 43 33 36 24 / 100 90 20 05
LAWRENCEBURG 44 33 36 24 / 100 90 20 05
WAVERLY 39 30 34 22 / 100 90 20 05
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHAMBURGER
AREA FORECAST DISCUSSION
NWS AUSTIN/SAN ANTONIO TX
1132 AM CST FRI DEC 28 2012
.AVIATION...
DRY SURFACE RIDGE OF HIGH PRESSURE BUILDING INTO S CENTRAL TX THIS
AFTERNOON AND PREVAILING TONIGHT AND SATURDAY. VFR CONDITIONS
PREVAILING FOR THE NEXT 24 HOURS...EXCEPT BKN-OVC MVFR CIGS WILL
SKIRT THE NERN PARTS OF S CENTRAL TX...NE OF A LINE FROM
KAGO(LLANO) TO KAUS(AUSTIN) TO K3T5(LA GRANGE) UNTIL ABOUT 00Z.
OTHERWISE NW-NLY WINDS OF 10-15 KNOTS WITH GUSTS TO 25 KNOTS THIS
AFTERNOON....BECOMING NEAR 10 KNOTS AFTER 00Z AND 5-10 KNOTS
SATURDAY.
&&
.PREV DISCUSSION... /ISSUED 1047 AM CST FRI DEC 28 2012/
UPDATE...
ADJUSTED TEMPS/DEWPOINTS/WEATHER AND SKY GRIDS ACCORDINGLY FOR REST OF
TODAY BASED ON LATEST SATELLITE PHOTOS/RADAR PROFILERS DATASETS AND
SURFACE OBSERVATIONS AS WELL AS RUC13 AND HIRES (NMM/ARW) MODELING
SOLUTIONS. NEW ZONES OUT SHORTLY.
DISCUSSION...
DRY AND STABLE CONDITIONS ARE IN STORE FOR SOUTH CENTRAL TEXAS
LATE THIS MORNING INTO THE UPCOMING WEEKEND IN THE WAKE OF A COLD
FRONT THAT MOVED THROUGH THE AREA EARLIER THIS MORNING. EXPECT
BREEZY NORTHWEST TO NORTH WINDS AT 15 TO 20 MPH WITH GUSTS UP TO
30 MPH THIS AFTERNOON...ESPECIALLY ACROSS THE WESTERN HALF OF
SOUTH CENTRAL TEXAS. AS A FRIENDLY REMINDER...A RED FLAG WARNING
IS IN EFFECT FROM NOON UNTIL 7 PM CST THIS EVENING ACROSS THE
WESTERN HALF OF OUR AREA DUE TO THIS CONDITIONS AND HUMIDITY
VALUES FALLING TO THE TEENS AND 20 PERCENT RANGE.
PREV DISCUSSION... /ISSUED 646 AM CST FRI DEC 28 2012/
UPDATE...
WITH WEAK COOL AIR ADVECTION BREAKING UP MOST OF THE FOG...THIS
UPDATE ALSO LOWERS HIGH TEMPERATURES UP TO 3 DEGREES OVER CENTRAL
COUNTIES. WARMER TEMPERATURES UP TO THE LOW 70S REMAINS EXPECTED
OVER FAR SW COUNTIES ONCE THE MID LEVEL WESTERLIES MIX DOWN WITH
THE BASE OF THE UPPER TROUGH PASSING TO THE NORTH.
PREV DISCUSSION... /ISSUED 550 AM CST FRI DEC 28 2012/
AVIATION...
/12Z TAFS/
COLD FRONT WILL PROGRESS RAPIDLY EASTWARD THIS MORNING AS DRY AIR
MIXES DOWN IN WEST NORTHWEST FLOW ALOFT. KDRT TERMINAL VFR CONDITIONS
WITH A GRADUAL INCREASE IN NORTHWEST WINDS FROM 5 TO 10 KTS EARLY
THIS MORNING TO NORTHWEST TO NORTH 15 TO 25 KTS BY NOON. NORTH
WINDS LOWERING TO 5 TO 10 KTS AFTER DARK. KAUS TERMINAL GRADUAL
LIFTING TO IFR CIGS VSBYS LIFTING TO MVFR IN FOG AND PATCHY
DRIZZLE. BY LATE MORNING CONDITIONS BECOMING VFR. NORTHWEST WINDS
5 TO 10 KTS INCREASING TO NORTHWEST TO NORTH AT 10 TO 15 KTS BY
LATE MORNING. KSAT TERMINAL MVFR CIGS AND VSBYS IN FOG EARLY THIS
MORNING BECOMING VFR BY LATE MORNING. NORTHWEST WINDS 5 TO 10 KTS
BECOMING NORTH 15 TO 25 KTS BY MIDDAY AND LOWERING TO NORTH AROUND
10 KTS AFTER DARK.
PREV DISCUSSION... /ISSUED 406 AM CST FRI DEC 28 2012/
DISCUSSION...
DENSE FOG EVENT CONTINUES ACROSS NEARLY ALL COUNTIES. AS A COLD FRONT
DRAWS CLOSER TO THE AREA...SOME ADJUSTMENT MAY BE NEEDED TO THE
HAZARD AREA THAT CONTINUES AFTER DAYBREAK. BY NOON MODELS SHOW ALL
THE FOG CLEARED OF THE AREA...ALONG WITH ANY PRECIPITATION. COLD
AIR OVER THE CENTRAL PLAINS ENHANCED BY SNOWFALL SHOULD REINFORCE
FREEZING NIGHTTIME TEMPERATURES OVER ALL AREAS FOR SATURDAY
MORNING. WILL AVOID FORECASTING THE COLDER GUIDANCE NUMBERS...AS
WINDS WILL NOT HAVE A CHANCE TO DECOUPLE BY DAYBREAK SATURDAY.
FILTERED SUNSHINE FROM THIN HIGH CLOUDS AND THE COLD ADVECTION
SHOULD KEEP AFTERNOON HIGHS ABOUT 10 DEGREES BELOW NORMAL...WITH
ANOTHER FREEZE TO FOLLOW FOR MOST AREAS SUNDAY. AREAS TO THE
SOUTHWEST MAY NOT HIT FREEZING SUNDAY DUE TO INCREASING CLOUDS AND
RETURN FLOW ABOUT THE SURFACE RIDGE.
LATE SUNDAY THROUGH MONDAY NIGHT...GOOD RAIN CHANCES DEVELOP OVER
TX AS AN UPPER TROUGH DIGS OVER NW MEXICO. THE RUN-TO-RUN GFS
MODEL TRENDS FAVOR DECREASING TROUGH DEPTH WHICH IS A COMMON GFS
TRAIT TO OVERFORECAST RAIN FOR THE AREA IN THE MEDIUM RANGE. WILL
CONTINUE TO SCALE BACK POPS OFF THE MEX GUIDANCE BY ABOUT 20-30
PERCENT MONDAY. THE GENERAL PATTERN OF THE GFS IS FAVORED OVER THE
ECMWF WHICH OFFERS A MORE PROLONGED OPPORTUNITY FOR RAIN FROM A
SECONDARY UPPER LOW TO MOVE THROUGH WEDNESDAY.
NEW YEARS EVE PROJECTIONS THUS FAVOR A DAMP EVENING FOR MOST
AREAS...WITH DRYING AND A REINFORCING COLD FRONT OVERNIGHT ON THE
1ST. FURTHER NORTHWARD ADJUSTMENTS OF THE UPPER TROUGH COULD MEAN
A MORE FIRE WEATHER SENSITIVE FORECAST FOR NEW YEARS EVE. THE
SECONDARY UPPER LOW COULD ALSO PRESENT SOME WINTER WEATHER
POSSIBILITIES FOR WEDNESDAY...BUT WITH THE MEDIUM RANGE FORECSTS
IN LOW CONFIDENCE...WILL STEER CLEAR OF PROJECTING ANY WINTER
WEATHER FOR NOW.
FIRE WEATHER...
A LOW END CRITICAL FIRE WEATHER EVENT FOR TODAY MAY NEED TO BE
CONSIDERED FOR AT LEAST THE WESTERN 1/3. RH VALUES WILL LIKELY
REACH CRITERIA OVER THE RIO GRANDE PLAINS...BUT THE WIND SPEEDS
WILL BE MARGINAL GIVEN THE EXPECTED MIXING OF DIRECTIONAL SHEAR IN
THE WINDS ALOFT TO POSSIBLY LOWER SURFACE WINDS BEHIND THE FRONT.
&&
.PRELIMINARY POINT TEMPS/POPS...
AUSTIN CAMP MABRY 60 26 52 29 55 / 10 0 0 0 10
AUSTIN BERGSTROM INTL AIRPORT 61 26 51 21 55 / 10 0 0 0 10
NEW BRAUNFELS MUNI AIRPORT 64 28 54 26 57 / 10 0 0 0 10
BURNET MUNI AIRPORT 55 24 49 26 51 / 10 0 0 0 10
DEL RIO INTL AIRPORT 66 31 55 34 54 / 0 0 0 - 20
GEORGETOWN MUNI AIRPORT 59 23 51 25 54 / 10 0 0 0 10
HONDO MUNI AIRPORT 65 26 55 28 55 / 10 0 0 - 10
SAN MARCOS MUNI AIRPORT 62 28 53 24 56 / 10 0 0 0 10
LA GRANGE - FAYETTE REGIONAL 63 30 52 30 57 / 30 0 0 0 10
SAN ANTONIO INTL AIRPORT 65 29 54 29 56 / 10 0 0 0 10
STINSON MUNI AIRPORT 67 29 55 30 57 / 10 0 0 0 10
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING UNTIL 7 PM CST THIS EVENING FOR THE FOLLOWING
COUNTIES: ATASCOSA...BANDERA...BEXAR...DIMMIT...EDWARDS...FRIO...
GILLESPIE...KENDALL...KERR...KINNEY...MAVERICK...MEDINA...REAL...
UVALDE...VAL VERDE...ZAVALA.
&&
$$
MESOSCALE/AVIATION...01
SYNOPTIC/GRIDS...17
PUBLIC SERVICE/DATA COLLECTION...30
AREA FORECAST DISCUSSION...UPDATED
NWS AUSTIN/SAN ANTONIO TX
1047 AM CST FRI DEC 28 2012
.UPDATE...
ADJUSTED TEMPS/DEWPOINTS/WEATHER AND SKY GRIDS ACCORDINGLY FOR REST OF
TODAY BASED ON LATEST SATELLITE PHOTOS/RADAR PROFILERS DATASETS AND
SURFACE OBSERVATIONS AS WELL AS RUC13 AND HIRES (NMM/ARW) MODELING
SOLUTIONS. NEW ZONES OUT SHORTLY.
&&
.DISCUSSION...
DRY AND STABLE CONDITIONS ARE IN STORE FOR SOUTH CENTRAL TEXAS
LATE THIS MORNING INTO THE UPCOMING WEEKEND IN THE WAKE OF A COLD
FRONT THAT MOVED THROUGH THE AREA EARLIER THIS MORNING. EXPECT
BREEZY NORTHWEST TO NORTH WINDS AT 15 TO 20 MPH WITH GUSTS UP TO
30 MPH THIS AFTERNOON...ESPECIALLY ACROSS THE WESTERN HALF OF
SOUTH CENTRAL TEXAS. AS A FRIENDLY REMINDER...A RED FLAG WARNING
IS IN EFFECT FROM NOON UNTIL 7 PM CST THIS EVENING ACROSS THE
WESTERN HALF OF OUR AREA DUE TO THIS CONDITIONS AND HUMIDITY
VALUES FALLING TO THE TEENS AND 20 PERCENT RANGE.
&&
.PREV DISCUSSION... /ISSUED 646 AM CST FRI DEC 28 2012/
UPDATE...
WITH WEAK COOL AIR ADVECTION BREAKING UP MOST OF THE FOG...THIS
UPDATE ALSO LOWERS HIGH TEMPERATURES UP TO 3 DEGREES OVER CENTRAL
COUNTIES. WARMER TEMPERATURES UP TO THE LOW 70S REMAINS EXPECTED
OVER FAR SW COUNTIES ONCE THE MID LEVEL WESTERLIES MIX DOWN WITH
THE BASE OF THE UPPER TROUGH PASSING TO THE NORTH.
PREV DISCUSSION... /ISSUED 550 AM CST FRI DEC 28 2012/
AVIATION...
/12Z TAFS/
COLD FRONT WILL PROGRESS RAPIDLY EASTWARD THIS MORNING AS DRY AIR
MIXES DOWN IN WEST NORTHWEST FLOW ALOFT. KDRT TERMINAL VFR CONDITIONS
WITH A GRADUAL INCREASE IN NORTHWEST WINDS FROM 5 TO 10 KTS EARLY
THIS MORNING TO NORTHWEST TO NORTH 15 TO 25 KTS BY NOON. NORTH
WINDS LOWERING TO 5 TO 10 KTS AFTER DARK. KAUS TERMINAL GRADUAL
LIFTING TO IFR CIGS VSBYS LIFTING TO MVFR IN FOG AND PATCHY
DRIZZLE. BY LATE MORNING CONDITIONS BECOMING VFR. NORTHWEST WINDS
5 TO 10 KTS INCREASING TO NORTHWEST TO NORTH AT 10 TO 15 KTS BY
LATE MORNING. KSAT TERMINAL MVFR CIGS AND VSBYS IN FOG EARLY THIS
MORNING BECOMING VFR BY LATE MORNING. NORTHWEST WINDS 5 TO 10 KTS
BECOMING NORTH 15 TO 25 KTS BY MIDDAY AND LOWERING TO NORTH AROUND
10 KTS AFTER DARK.
PREV DISCUSSION... /ISSUED 406 AM CST FRI DEC 28 2012/
DISCUSSION...
DENSE FOG EVENT CONTINUES ACROSS NEARLY ALL COUNTIES. AS A COLD FRONT
DRAWS CLOSER TO THE AREA...SOME ADJUSTMENT MAY BE NEEDED TO THE
HAZARD AREA THAT CONTINUES AFTER DAYBREAK. BY NOON MODELS SHOW ALL
THE FOG CLEARED OF THE AREA...ALONG WITH ANY PRECIPITATION. COLD
AIR OVER THE CENTRAL PLAINS ENHANCED BY SNOWFALL SHOULD REINFORCE
FREEZING NIGHTTIME TEMPERATURES OVER ALL AREAS FOR SATURDAY
MORNING. WILL AVOID FORECASTING THE COLDER GUIDANCE NUMBERS...AS
WINDS WILL NOT HAVE A CHANCE TO DECOUPLE BY DAYBREAK SATURDAY.
FILTERED SUNSHINE FROM THIN HIGH CLOUDS AND THE COLD ADVECTION
SHOULD KEEP AFTERNOON HIGHS ABOUT 10 DEGREES BELOW NORMAL...WITH
ANOTHER FREEZE TO FOLLOW FOR MOST AREAS SUNDAY. AREAS TO THE
SOUTHWEST MAY NOT HIT FREEZING SUNDAY DUE TO INCREASING CLOUDS AND
RETURN FLOW ABOUT THE SURFACE RIDGE.
LATE SUNDAY THROUGH MONDAY NIGHT...GOOD RAIN CHANCES DEVELOP OVER
TX AS AN UPPER TROUGH DIGS OVER NW MEXICO. THE RUN-TO-RUN GFS
MODEL TRENDS FAVOR DECREASING TROUGH DEPTH WHICH IS A COMMON GFS
TRAIT TO OVERFORECAST RAIN FOR THE AREA IN THE MEDIUM RANGE. WILL
CONTINUE TO SCALE BACK POPS OFF THE MEX GUIDANCE BY ABOUT 20-30
PERCENT MONDAY. THE GENERAL PATTERN OF THE GFS IS FAVORED OVER THE
ECMWF WHICH OFFERS A MORE PROLONGED OPPORTUNITY FOR RAIN FROM A
SECONDARY UPPER LOW TO MOVE THROUGH WEDNESDAY.
NEW YEARS EVE PROJECTIONS THUS FAVOR A DAMP EVENING FOR MOST
AREAS...WITH DRYING AND A REINFORCING COLD FRONT OVERNIGHT ON THE
1ST. FURTHER NORTHWARD ADJUSTMENTS OF THE UPPER TROUGH COULD MEAN
A MORE FIRE WEATHER SENSITIVE FORECAST FOR NEW YEARS EVE. THE
SECONDARY UPPER LOW COULD ALSO PRESENT SOME WINTER WEATHER
POSSIBILITIES FOR WEDNESDAY...BUT WITH THE MEDIUM RANGE FORECSTS
IN LOW CONFIDENCE...WILL STEER CLEAR OF PROJECTING ANY WINTER
WEATHER FOR NOW.
FIRE WEATHER...
A LOW END CRITICAL FIRE WEATHER EVENT FOR TODAY MAY NEED TO BE
CONSIDERED FOR AT LEAST THE WESTERN 1/3. RH VALUES WILL LIKELY
REACH CRITERIA OVER THE RIO GRANDE PLAINS...BUT THE WIND SPEEDS
WILL BE MARGINAL GIVEN THE EXPECTED MIXING OF DIRECTIONAL SHEAR IN
THE WINDS ALOFT TO POSSIBLY LOWER SURFACE WINDS BEHIND THE FRONT.
&&
.PRELIMINARY POINT TEMPS/POPS...
AUSTIN CAMP MABRY 26 52 29 55 46 / 0 0 0 10 30
AUSTIN BERGSTROM INTL AIRPORT 26 51 21 55 42 / 0 0 0 10 30
NEW BRAUNFELS MUNI AIRPORT 28 54 26 57 45 / 0 0 0 10 30
BURNET MUNI AIRPORT 24 49 26 51 43 / 0 0 0 10 40
DEL RIO INTL AIRPORT 31 55 34 54 44 / 0 0 - 20 20
GEORGETOWN MUNI AIRPORT 23 51 25 54 42 / 0 0 0 10 30
HONDO MUNI AIRPORT 26 55 28 55 46 / 0 0 - 10 30
SAN MARCOS MUNI AIRPORT 28 53 24 56 44 / 0 0 0 10 30
LA GRANGE - FAYETTE REGIONAL 30 52 30 57 47 / 0 0 0 10 30
SAN ANTONIO INTL AIRPORT 29 54 29 56 47 / 0 0 0 10 30
STINSON MUNI AIRPORT 29 55 30 57 47 / 0 0 0 10 30
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING UNTIL 7 PM CST THIS EVENING FOR THE FOLLOWING
COUNTIES: ATASCOSA...BANDERA...BEXAR...DIMMIT...EDWARDS...FRIO...
GILLESPIE...KENDALL...KERR...KINNEY...MAVERICK...MEDINA...REAL...
UVALDE...VAL VERDE...ZAVALA.
&&
$$
MESOSCALE/AVIATION...01
SYNOPTIC/GRIDS...17
PUBLIC SERVICE/DATA COLLECTION...30
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
702 AM CST FRI DEC 28 2012
.UPDATE...
SNOW HAS STRUGGLED TO DEVELOP ACROSS THE SOUTH BUT HAS FINALLY
STARTED AT KDBQ KMRJ AND KLNR THIS HOUR. DRY LAYER AROUND 850 MB
HAS STRUGGLED TO MOISTEN AND THAT HAS DELAYED START OF SNOW IN THE
SOUTH. GIVEN LOW LEVEL ASCENT AND LACK OF ICE CRYSTALS HAVE HAD A
PERIOD OF FREEZING DRIZZLE HERE IN THE WAUKESHA/JEFFERSON COUNTY
AREA SO ADDED FREEZING DRIZZLE IN SOUTHEAST 1/4 OF CWA FOR THE
MORNING.
MEANWHILE SNOW FILLING IN NICELY ACROS NORTHERN HALF GENERALLY
ALONG AND NORTH OF SURFACE TROUGH/REMNANTS OF LAKE BAND. EASTERLY
LOW LEVEL FLOW OFF LAKE APPEARS TO BE HELPING THE SEEDING AND
MOISTENING PROCESS AND WE SHOULD ALSO SEE LAKE ENHANCEMENT IN THAT
AREA SO ADVISORY STILL LOOKS GOOD.
GIVEN DRY AIR AND SLIGHTLY DRIER LOOK TO 06Z NAM/GFS AND MOST
RECENT RAP MODELS IN THE SOUTH...ADJUSTED DOWN THE QPF AND SNOW
AMOUNTS ABOUT AN INCH MOST AREAS BUT ESPECIALLY TOWARD ILLINOIS
BORDER IN SOUTHEAST. WILL NOT BE SURPRISED TO SEE LESS THAN AN
INCH IN THAT AREA.
RECENT RAP RUNS CONTINUE TO SHOW DECENT LIFT IN THE DENDRITE
GROWTH ZONE (-12 TO -18C) OVER THE NORTHERN PART OF CWA. THAT
COUPLED WITH LAKE ENHANCEMENT SHOULD ALLOW HIGHER SNOW TOTALS TO
VERIFY.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...WINTER WEATHER ADVISORY UNTIL 3 AM CST SATURDAY FOR WIZ046-047-
051-052-058>060.
LM...NONE.
&&
$$
UPDATE...CRAVEN
TODAY/TONIGHT AND AVIATION/MARINE...CRAVEN
SATURDAY THROUGH THURSDAY...KAPELA
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
1248 AM EST SUN DEC 30 2012
.SYNOPSIS...
A REINFORCING COLD FRONT WILL MOVE THROUGH THIS EVENING FOLLOWED
BY HIGH PRESSURE THROUGH SUNDAY WHICH WILL THEN SHIFT OFFSHORE BY
MONDAY. ANOTHER FRONTAL SYSTEM WILL DROP INTO THE SOUTHEAST UNITED
STATES TUESDAY AND PERSIST IN THE VICINITY THROUGH THURSDAY NIGHT.
HIGH PRESSURE WILL BUILD BACK IN FOR LATE NEXT WEEK INTO THE
WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
MAINLY CLEAR SKIES AND COLDER TEMPS OVERNIGHT. VERY FEW/MINOR
CHANGES ON THE MIDNIGHT PACKAGE. SURFACE WINDS HAVE BEEN QUITE
GUSTY OVER LAND AREAS FOR THIS TIME OF NIGHT DUE TO COLD AIR
ADVECTION. AS HIGH PRES BUILDS LATER TONIGHT...GUSTS WILL SUBSIDE
AND SPEEDS SHOULD DIMINISH TO 10 MPH OR LESS NEARING DAWN.
LAKE WINDS...A LAKE WIND ADVISORY REMAINS IN FORCE UNTIL 5 AM
SUNDAY FOR LAKE MOULTRIE. GUSTY WINDS WILL CONTINUE AS A STRONGER
SURGE OF COLD AIR MOVES ACROSS THE RELATIVELY WARMER LAKE WATERS.
WAVES OF 1-2 FT WILL OCCUR...HIGHEST OVER THE CENTRAL AND
SOUTHEAST PORTIONS OF THE LAKE.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY/...
SUNDAY AND SUNDAY NIGHT...LARGE AND PROMINENT RIDGING ALOFT WILL
BUILD IN FROM THE WEST. AT THE SURFACE...A 1030 MB HIGH WILL SHIFT
EASTWARD INTO THE FORECAST AREA AND LINGER THROUGH THE OVERNIGHT.
DEEP DRY AIR AND LARGE SCALE SUBSIDENCE WILL RESULT IN A DRY AND
CLEAR DAY/NIGHT. COLD AIR ADVECTION WILL CONTINUE THROUGH THE DAY
RESULTING IN COOL HIGH TEMPS. LOW LEVEL THICKNESSES SUPPORT HIGHS
STRUGGLING TO REACH THE LOW 50S. WITH EXCELLENT RADIATIONAL COOLING
CONDITIONS SUNDAY NIGHT...LOWS WILL BOTTOM OUT IN THE UPPER 20S AWAY
FROM THE COAST.
MONDAY THROUGH TUESDAY...THE UPPER RIDGE WILL FLATTEN OUT AND THE
FLOW WILL BECOME MORE ZONAL IN RESPONSE TO A POSITIVELY TILTED
TROUGH PUSHING INTO THE OH VALLEY. AS A RESULT A STRENGTHENING 150
KT UPPER LEVEL JET WILL EXTEND WEST TO EAST ACROSS THE UPPER MIDWEST
AND MID ATLANTIC. THIS WILL HELP DRIVE SURFACE LOW AND COLD FRONT
DEVELOPMENT OVER THE LOWER MS VALLEY BY TUESDAY MORNING. THE FRONT
WILL CONTINUE TO DRIFT EASTWARD WITH PRECIP EXPECTED TO BE OUR THE
DOORSTEP OF THE FORECAST AREA BY TUESDAY AFTERNOON. EXPECT MONDAY TO
BE DRY WITH INCREASING HIGH CLOUDS AND TEMPS RIGHT AROUND NORMAL.
TUESDAY CONTINUES TO FEATURE A DRY MORNING AND POPS INCREASING INTO
THE CHANCE RANGE FOR THE AFTERNOON. AS OF RIGHT NOW...MODELS ARE IN
GOOD AGREEMENT KEEPING THE BULK OF THE PRECIP TO OUR WEST THROUGH
THE DAY.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
TUESDAY NIGHT THROUGH THURSDAY NIGHT LOOK FAIRLY ACTIVE DUE TO A
PLETHORA OF UPPER DISTURBANCES RIPPLING THROUGH THE BROAD EASTERN
UNITED STATES TROUGH. A WEAK FRONT SHOULD REMAIN DRAPED ACROSS THE
FORECAST AREA WITH NUMEROUS SURFACE WAVES RIDING ALONG IT. WE KEPT
CHANCE POPS IN THE FORECAST THROUGH THURSDAY...TAPERING OFF THURSDAY
NIGHT. COOL...DRY HIGH PRESSURE WILL BUILD IN FRIDAY THROUGH
SATURDAY.
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
VFR AT KSAV/CHS THROUGH 06Z/31. ENHANCED SURFACE WIND GUSTS WILL
SLOWLY DROP OFF OVERNIGHT.
EXTENDED AVIATION OUTLOOK...INCREASING CHANCES FOR SUB-VFR
CONDITIONS LATE TUESDAY AND WEDNESDAY AS A COLD FRONT DROPS SOUTH
INTO THE AREA.
&&
.MARINE...
TONIGHT...WINDS WILL INCREASE EVEN MORE TONIGHT AS A SECONDARY
SURGE OF COLD AIR PUSHES OFF THE COAST AND INTERACTS WITH THE
RELATIVE WARMER ATLANTIC WATERS. SMALL CRAFT ADVISORIES LOOKS WELL
PLACED...BUT OPTED TO UPGRADE TO A GALE WARNING FOR THE GEORGIA
OFFSHORE WATERS WHERE SIGNIFICANTLY WARMER WATERS ASSOCIATED WITH
THE WESTERN WALL OF THE GULF STREAM ARE LOCATED. YESTERDAY/S 1KM
MODIS SEA SURFACE TEMPERATURE DATA INDICATED WATER TEMPERATURES
QUICKLY WARM FROM THE LOWER-MID 50S AROUND 20 NM TO THE LOWER 70S
BEYOND 40 NM. RUC AND H3R BOUNDARY LAYER WIND FORECAST SUGGEST
WINDS COULD EASILY REACH SOLID GALES OF 30-35 KT WITH GUSTS TO 40
KT IN THE OUTER HALF OF THE GEORGIA OFFSHORE ZONES WHERE THE
WARMER WATER TEMPERATURES WILL FAVOR MORE INTENSE VERTICAL MIXING.
OBSERVATIONS FROM 41004 WERE ALREADY GUSTING NEAR 35 KT AT 29/22Z
SO THINK A GALE WARNING IS CERTAINLY WARRANTED ATTM AS WINDS
INCREASE FURTHER. WILL WORD THE HIGHEST WINDS BEYOND 40 NM IN
BOTH THE GALE WARNING ITSELF AND THE COASTAL WATERS FORECAST. SEAS
WILL BUILD AS HIGH 9 FT OFFSHORE...BUT WILL ACTUALLY SUBSIDE A
BIT NEAR THE IMMEDIATE COAST AS THE OFFSHORE FLOW INTENSIFIES.
SUNDAY THROUGH THURSDAY...HIGH PRESSURE WILL BUILD INTO THE AREA ON
SUNDAY. THE MORNING WILL CONTINUE TO SEE ELEVATED SEAS AND STRONG NW
WINDS AS THE WATERS ARE CAUGHT IN THE PINCHED GRADIENT BETWEEN THE
APPROACHING HIGH AND DEPARTING LOW. CONDITIONS SHOULD IMPROVE
QUICKLY INTO THE AFTERNOON...ALLOWING FOR ALL SMALL CRAFT ADVISORIES
TO COME DOWN. THINGS WILL THEN BE QUIET THROUGH MONDAY AS THE HIGH
PASSES OVER THE AREA. INCREASING SOUTHWEST FLOW AHEAD OF THE NEXT
FRONT MAY PUSH WINDS AS HIGH AS 15-20 KT WITH SEAS REACHING 5 FT
OVER THE OUTER PORTIONS BY TUESDAY. A STRONGER SURGE WILL OCCUR LATE
NEXT WEEK WHEN COLD HIGH PRESSURE BUILDS OVER THE WATERS.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...LAKE WIND ADVISORY UNTIL 5 AM EST EARLY THIS MORNING FOR
SCZ045.
MARINE...SMALL CRAFT ADVISORY UNTIL 9 AM EST THIS MORNING FOR AMZ330-
350-352-354.
GALE WARNING UNTIL 5 AM EST EARLY THIS MORNING FOR AMZ374.
&&
$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...BSH
LONG TERM...BSH
AVIATION...
MARINE...ST
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1157 PM CST SAT DEC 29 2012
.DISCUSSION...
ISSUED 859 PM CST SAT DEC 29 2012
CLEARING EVIDENT ON SAT IMAGERY AND RAPID COOLING ALREADY TAKING
PLACE. DROPPED TEMPS A COUPLE OF DEGREES...AND ADDED WORDING FOR
POTENTIAL PATCHY FOG DEVELOPMENT. HAVE NOT LOST LLVL MOISTURE...
PARTICULARLY IN THE SW...AND IN THE NORTH...THE DEWPOINTS ARE A
LITTLE HIGHER...BUT THE TEMPS ARE DROPPING A LITTLE LOWER...AND
QUICKLY. FOR THE MOST PART THOUGH...FORECAST IS LOOKING GOOD.
CHANGED SOME TRENDS HERE AND THERE...FRESHENED THE HRLY TEMPS AND
THE SKY GRIDS. ZONES OUT MOMENTARILY.
&&
.AVIATION...
ISSUED 1152 PM CST SAT DEC 29 2012
CLEAR SKIES OVERNIGHT MAY END UP WITH PATCHY REDUCTIONS IN VIS
OVERNIGHT...BUT SPARSE ENOUGH NOT WILLING TO PUT IN ANY OF THE TAF
SITES JUST YET. TIMING OF CIRRUS RETURN IN MODELS A BIT DIFFERENT
FROM GFS TO NAM...AND THIS TIME TOMORROW NIGHT SHOULD ALSO SEE
SOME MID LEVEL CLOUDS MOVING INTO THE REGION. UNTIL THEN...VFR
AND CLOUDS BECOMING INCREASINGLY SOUTHERLY BY MIDDAY TOMORROW.
HJS
&&
.PREV DISCUSSION...
ISSUED 220 PM CST SAT DEC 29 2012
THE MAIN CONCERN IS THE STORM SYSTEM FOR MONDAY AND NEW YEARS EVE.
MAJOR DIFFERENCES ARE STILL SHOWING UP BETWEEN THE MODELS ON THIS
ONE. THE NAM IS MUCH STRONGER AND FARTHER NORTH WITH THE BAND OF
HEAVY SNOW...INDICATING 4-7 INCHES OF SNOW ACROSS A LARGE PORTION
OF CENTRAL IL...NORTH OF I-70. PART OF THAT HAS TO DO WITH ITS
CONTINUATION OF STEADY SNOWS IN THE NORTH OVERNIGHT NEW YEARS
EVE...WHERE THE OTHER MODELS DROP PRECIP OFF IN THE EVENING. THAT
ADDITIONAL SNOW SEEMS TO BE LINKED TO THE NAM BEING THE ONLY
MODEL TO TAKE A LOW PRESSURE CENTER ACROSS SOUTHERN ILLINOIS NEW
YEARS EVE NIGHT.
THE CANADIAN GEM HAS A SIMILAR PATH FOR THE SNOW BAND AS THE
NAM...BUT HAS LESS ACCUMULATION. THE ECMWF/GFS/UKMET ARE ALL
MUCH FARTHER SOUTH AND WEAKER WITH THE DYNAMICS/PRECIP IN OUR
AREA. THEY DO INDICATE 2-3 INCHES COULD ACCUMULATE SOUTHEAST OF
I-70...WITH THE NORTHERN EDGE OF 1 INCH NEAR I-72. THAT IS THE
PATH THAT HPC HAS GENERALLY FOLLOWED...AND WE WERE PRIMARILY
INDICATING THAT IN OUR GRIDS. HOWEVER...THE NAM AND RAP WERE THE
ONLY MODELS TO SHOW THE AMOUNT OF SNOW WE PICKED UP IN OUR
SOUTHEAST COUNTIES LAST NIGHT...SO THAT LEAVES SOME UNEASY CONCERN
FOR SUCH A BUSY HOLIDAY NIGHT...IF THAT SNOW BAND DOES SHIFT
NORTH.
WE WILL GENERALLY STAY THE COURSE FOR NOW AND ADJUST AMOUNTS
SLIGHTLY TOWARD THE CURRENT SOUTHWARD CONSENSUS.
SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT
AFTER SOME LINGERING LIGHT SNOW SHOWERS/FLURRIES DEPART TO THE
EAST THIS EVENING...CLEARING SKIES APPEAR POISED TO MOVE INTO
CENTRAL ILLINOIS. NIGHT TIME MOISTURE/CLOUD TRENDS CAN BE A BIT
TRICKY WITH ADVANCING HIGH PRESSURE...SINCE THE SUBSIDENCE
INVERSION CAN SOMETIMES TRAP LOW LEVEL MOISTURE THAT THE WEAKER
LOW LEVEL WINDS ARE UNABLE TO PUSH OUT. THAT CAN LEAD TO BACK-
BUILDING LOW CLOUDS/STRATUS AT NIGHT...AFTER A STEADY CLEARING
PROGRESS IS EVIDENT BEFORE SUNSET. PILOT REPORTS CONFIRM THE THIN
LAYER OF MOISTURE OF THIS CLOUD DECK...SO THE CLEARING MAY
CONTINUE TONIGHT AS ADVERTISED IN THE MODELS. WE DID SLOW DOWN THE
PROGRESSION IN THE SKY GRIDS...BUT DO EVENTUALLY CLEAR THINGS OUT
IN THE EAST TOWARD MORNING.
THE TIMING OF THE CLEARING CAN HAVE A BIG IMPACT ON LOW
TEMPERATURES...BUT WITH CLEARING EXPECTED IN MOST AREAS BY
MORNING...WE SHOULD BE SEE LOWS DROP BELOW NORMAL ACROSS THE
BOARD...WITH SOME SINGLE DIGIT LOWS NW OF THE IL RIVER.
HIGH PRESSURE WILL PROVIDE SUNNY SKIES AND QUIET CONDITIONS ON
SUNDAY...BUT THE QUICKLY APPROACHING LOW PRESSURE SYSTEM WILL
BRING INCREASING CLOUDS SUNDAY NIGHT.
MONDAY MORNING...SNOW SHOULD BEGIN TO ADVANCE ACROSS OUR CENTRAL
COUNTIES FROM SW TO NE. LOOKING AT THE CONSENSUS MODELS
(ECMWF/GFS/UKMET) IT APPEARS THAT THE MAIN PERIOD OF STEADIER
SNOWS WILL BE MONDAY AFTERNOON AND EVENING...WHERE MOST OF THE
ACCUMULATION WILL OCCUR. SNOWFALL TOTALS UNDER THAT SCENARIO WOULD
RANGE FROM LESS THAN A HALF INCH TOWARD PEORIA...WITH THE ONE INCH
LINE AS FAR NORTH AS A LINE FROM RUSHVILLE TO LINCOLN TO
CHAMPAIGN...1-2" FROM THAT LINE SOUTH TO I-70...AND 2-3" SOUTH OF
I-70.
SOME SNOW SHOWERS MAY LINGER IN THE SOUTHEAST AFTER MIDNIGHT NEW
YEARS EVE...BUT PRECIP SHOULD COME TO AN END BY SUNRISE ON
TUESDAY. CLEARING SKIES ARE EVEN FORECAST FOR THE AFTERNOON AS
HIGH PRESSURE BUILDS INTO THE AREA FROM THE WEST. A COLD NIGHT
WILL BE ON TAP TUES NIGHT UNDER CLEAR SKIES AND LIGHT
WINDS...ALONG WITH A FRESH SNOW COVER. LOW TEMPS WOULD LIKELY DROP
BELOW GUIDANCE AND INTO THE SINGLE DIGITS IN MANY AREAS.
LONG TERM...WEDNESDAY THROUGH SATURDAY.
THE EXTENDED PERIOD WILL BE DOMINATED BY COLD AND DRY CONDITIONS
UNDER SURFACE HIGH PRESSURE. THE NORTHERN STEAM STORM TRACK LOOKS
TO REMAIN FARTHER NORTH ACROSS THE GREAT LAKES...AND THE SOUTHERN
STREAM REMAINS SOUTH...PUSHING STORM SYSTEMS ACROSS THE GULF
COAST. WE WILL KEEP HIGHS AND LOWS BELOW NORMAL...WITH THE COLDEST
NIGHT LOOKING LIKE THURSDAY NIGHT.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1144 PM CST SAT DEC 29 2012
.AVIATION...
STRATUS WITH LIFR TO IFR CIGS OVER NORTH CENTRAL INTO NORTHEAST
IOWA NOT BEING WELL HANDLED BY MODELS EXCEPT FOR THE RAP MODEL
WHICH HAS IDEA OF THE CLOUDS BUT WAY OVERDONE ON EXTENT. RECENT
SATELLITE LOOPS SHOWS THE CLOUDS MOVING E/ESE... WHICH PUTS THEM
ON TRAJECTORY TO IMPACT AT LEAST KDBQ OVERNIGHT INTO SUNDAY
MORNING WITH PERIOD OF IFR TO LIFR CIGS ALONG WITH FOG. CANT RULE
OUT EVEN A PERIOD OF DENSE FOG AT KDBQ TOWARD DAYBREAK AS WELL
BUT LOW CONFIDENCE TO INCLUDE ATTIM. SOME CONCERN THAT IFR TO
LIFR CIGS MAY PROPAGATE AND/OR DEVELOP FURTHER SOUTH TO KCID AND
KMLI TERMINALS LATE TONIGHT INTO SUNDAY MORNING BASED ON THE LOW
LEVEL WIND FIELDS FROM W/NW. HOWEVER... LOW CONFIDENCE PRECLUDES
ANY INCLUSION OF LOW CIGS AT KCID AND KMLI ATTIM AND PASS TO NEXT
SHIFT TO MONITOR. HAVE KEPT MENTION OF BR WITH VSBYS 2-5SM AT
KCID...KMLI AND KBRL THROUGH DAYBREAK. ANY LOW CLOUDS AND FOG
LIKELY TO DISSIPATE WITH VFR CONDITIONS AT ALL SITES BY LATE
MORNING INTO EARLY AFTERNOON WITH SOUTHERLY WINDS INCREASING TO
AROUND 10 KTS. OCCASIONAL GUSTS OF 15-18 KTS POSSIBLE AT TIMES
IN THE AFTERNOON. COLD FRONT TO APPROACH SUNDAY EVENING WITH WINDS
SHIFTING TO THE SOUTHWEST AROUND 10 KTS.
&&
.PREV DISCUSSION... /ISSUED 916 PM CST SAT DEC 29 2012/
UPDATE...
LOW CLOUDS EXITING FAR EAST SECTIONS ATTIM... WITH ATTENTION NOW
SHIFTING TO COUPLE OF AREAS OF LOW CLOUDS TO OUR N/NW. THE
LOW CLOUDS OVER MN INTO WI ARE ON BACK SIDE OF DEPARTING TROUGH.
MEANWHILE... SMALL AREA OF LOW CLOUDS OVER NW INTO NCTRL IA APPEARS
ATTENDANT TO ZONE OF LOW LEVEL WARM ADVECTION. MOST MODELS NOT
HANDLING THESE CLOUDS WELL EXCEPT RAP MODEL BUT IT IS OVERDONE WITH
EXTENT. LAST 60 MINS OF 11-3.9 MICRON SATELLITE LOOP SHOW LOW CLOUDS
MOVING NEARLY DUE EAST TO EVEN SLIGHTLY SOUTH OF EAST. THIS IS IN
LINE WITH LOW LEVEL WIND FIELDS WHICH ARE ROUGHLY FROM WNW OR ROUGHLY
280-290 DEGREES. ON THIS TRAJECTORY WOULD EXPECT SOME OF THESE LOW
CLOUDS TO MAKE IT INTO AT LEAST THE FAR NORTHERN CWA LATE EVE AND
OVRNGT. AS RESULT... WILL BE SENDING UPDATE TO INCREASE CLOUD COVER
MAINLY ALONG AND NORTH OF HWY 20. CANT RULE OUT DEVELOPMENT OR
PROPAGATION TO BRING LOW CLOUD DECK FARTHER SOUTH TOWARDS KCID TO
KSQI LINE... BUT WILL HOLD ON INCREASING CLOUDS THAT FAR SOUTH FOR
NOW AND CONTINUE TO MONITOR TRENDS. WITH THE LOW CLOUDS ALSO EXPECTING
SOME FLURRIES AS SEEN IN OBS. AS CLOUD TRENDS GO... SO GO THE TEMPS.
FOR NOW MADE FEW CHGS TO MINS NORTH WITH PROGRESSIVE NATURE OF THE
CLOUDS. ELSEWHERE... HAVE TRIMMED LOWS BY COUPLE DEGS IN MANY AREAS
WITH GENERALLY CLEAR SKIES.
PREV DISCUSSION... /ISSUED 307 PM CST SAT DEC 29 2012/
SYNOPSIS...
THE MORNING UA ANALYSIS SHOWED AN UPPER TROF OVER THE CENTRAL U.S.
THE MAIN TROF AXIS EXTENDED FROM LAKE MICHIGAN THROUGH THE LOWER
OHIO VALLEY WITH A SECONDARY SHORT WAVE OVER WESTERN IOWA. AT THE
SURFACE THE REGION WAS UNDER CYCLONIC FLOW ASSOCIATED WITH LOW
PRESSURE OFF THE MID ATLANTIC COAST. WIDESPREAD LOW CLOUDS OVER THE
AREA THIS MORNING WERE ACCOMPANIED BY SOME LIGHT SNOW. THE CLOUDS
HAVE BEEN STEADILY CLEARING FROM WEST TO EAST THROUGH EARLY THIS
AFTERNOON.
SHORT TERM...TONIGHT AND SUNDAY...
EXTRAPOLATION OF THE CLEARING LINE HAS THE BACK EDGE OF THE LOW
CLOUDS EAST OF THE CWFA BY 03Z. THIS LOOKS REASONABLE...EXCEPT FOR
NORTHWEST ILLINOIS WHERE MODEL PROGS HOLD HIGHER VALUES OF LOW LEVEL
RH THROUGH MIDNIGHT AS THE LOW LEVEL RIDGE BUILDS INTO THAT AREA
FIRST. HAVE SET THE GRIDS UP FOR A FASTER CLEARING TREND OVER THE
SOUTHWEST HALF OF THE AREA THIS EVENING AND A LITTLE SLOWER TREND IN
THE NORTHEAST. THERE IS ALSO SOME CONCERN FOR STRATUS AND FOG
DEVELOPING JUST EAST OF THE RIDGE AXIS LATE TONIGHT...SIMILAR TO
WHAT HAPPENED IN EASTERN SOUTH DAKOTA THIS MORNING. THE RAP AND NAM
5KM RH PROGS WERE HINTING AT THIS OCCURRING OVER EASTERN IA AFTER
MIDNIGHT. WHILE THIS CANNOT BE RULED OUT...THERE IS NOT ENOUGH
CONFIDENCE IN ITS OCCURRENCE TO INCLUDE IN THE FORECAST JUST YET.
CLEARING SKIES AND LIGHT WINDS TONIGHT SHOULD ALLOW FOR GOOD
RADIATIONAL COOLING WITH LOWS JUST BELOW ZERO NORTHWEST TO AROUND
10 IN THE SOUTHEAST. THE SURFACE RIDGE AXIS WILL BE EAST OF THE
AREA BY 12Z SUNDAY WITH SOUTH WINDS INCREASING DURING THE DAY AS THE
RIDGE CONTINUES TO MOVE EAST AND A COLD FRONT MOVES INTO NORTHWEST
IOWA. HIGH CLOUDS WILL ALSO BE ON THE INCREASE. TEMPERATURES WILL
BE A CHALLENGE TOMORROW WITH MODELS SHOWING A SHALLOW BUT STRONG
INVERSION OVER THE AREA. HIGHS IN THE MID 20S NORTH TO LOW 30S SOUTH
WERE BASED ON THE SHALLOW MIXING. IF WINDS ARE STRONGER THAN
FORECAST THEN...MIXING WILL BE DEEPER AND THE FORECAST HIGHS WILL BE
ON THE COLD SIDE. DLF
LONG TERM...MONDAY THROUGH SATURDAY
TWO MAIN CONCERNS IN THIS TIME FRAME ARE THE WEAK CYCLOGENESIS
EVENT WHICH COULD BRING PRECIP TO THE SOUTH LATE MONDAY AND EARLY
TUESDAY...AND THE MUDDLE AMONGST THE MODELS WITH THE UPPER AIR
PATTERN AND SUBSEQUENT DETAILS MIDWEEK.
REGARDING THE MONDAY EVENT...THE NAM IS MORE VIGOROUS AND FURTHER
NORTH WITH DEVELOPING THE LOW THAN THE GFS AND ECMWF...WHICH ARE
WEAKER AND FURTHER SOUTH. HAVE SHADED POPS TO FAVOR THE GFS/ECMWF
SOLUTIONS AND KEPT QPF/SNOW ON THE LIGHT SIDE.
AT MID WEEK...THE EXTENDED MODELS ARE INCONSISTENT AMONG
THEMSELVES AND FROM RUN TO RUN IN HANDLING THE COMPLEX SPLIT FLOW
PATTERN WHICH INCLUDES A SOUTHWEST U.S. CUTOFF AND AN ACTIVE
NORTHERN STREAM. THE 12Z ECMWF MOVES A CLIPPER SYSTEM TO OUR
NORTHEAST WEDNESDAY-THURSDAY...WHICH IS FURTHER NORTH AND EAST AT
THAN AT 00Z WHEN IT WAS PROGGED OVER OUR AREA. MEANWHILE...THE
12Z GFS PROGS THIS CLIPPER SYSTEM FASTER AND EVEN FURTHER
NORTHEAST...SO IT APPEARS THIS WOULD BE A NONEVENT FOR US.
THE GFS DOES HOLD MORE ENERGY BACK OVER THE NORTHERN ROCKIES WHICH
EVENTUALLY CUTS OFF AND DRIFTS ACROSS THE CENTRAL U.S. THROUGH
THE WEEKEND. HOWEVER...THIS GFS RUN IS AN OUTLIER RELATIVE TO THE 00Z
ENSEMBLE MEAN.
THUS FAITH IN ANY OF THESE SOLUTIONS IS LOW. HOWEVER...THE COMMON
THEME IS THAT TROUGHINESS DEVELOPS AND PROGRESSES THROUGH THE
CENTRAL U.S. LATE NEXT WEEK. THERE APPEARS TO BE NO SIGNIFICANT
PRECIP EVENT IN THIS TIME FRAME...AND INDICATIONS ARE THAT
REENFORCING COLD AIR MIGHT GIVE US OUR COLDEST TEMPS SO FAR THIS
SEASON SOMETIME LATE NEXT WEEK INTO THE WEEKEND. WOLF
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
245 AM EST SUN DEC 30 2012
.SYNOPSIS...
A CROSSING UPPER LEVEL DISTURBANCE WILL SPREAD LIGHT SNOW ACROSS
THE UPPER OHIO VALLEY REGION EARLY THIS MORNING. SIGNIFICANT SNOW
ACCUMULATION WILL BE CONFINED TO THE RIDGES.
&&
.NEAR TERM /THROUGH TODAY/...
NO CHANGES NEEDED FOR THE PREDAWN UPDATE OTHER THAN TO DIMINISH
POPS OVR WRN ZONES AS MID/UPR TROF HAS PROGRESSED FAR ENOUGH EWD
TO END SN SPPRT.
OTHERWISE...SHRTWV TROF WL CONT TO SPREAD LGT SNOW ACRS THE
REGION THIS MRNG. SIGNIFICANT ACCUMULATION WL DEPEND ON UPSLOPE
ENHANCEMENT...HENCE IS CONFINED TO THE RIDGES WHERE THE WINTER
WEATHER ADVISORY FOR FAYETTE AND WESTMO...AND WINTER STORM WARNING
FOR GARRETT...PRESTON...AND TUCKER COUNTIES WILL BE MAINTAINED.
SNOW SHOWER ACTIVITY WILL GRADUALLY DIMINISH...AND CEASE
ALTOGETHER BY MIDDAY AS SBSDNC INCRS...INVERSION LEVELS DROP/MID
LVL COLD POOL WITH THE DISTURBANCE SLIDES EWD.
NEAR TERM TEMPS WERE FORECAST USING A BLEND OF SREF MEANS AND THE
LATEST LAMP GUIDANCE.
&&
.SHORT TERM /TONIGHT THROUGH WEDNESDAY/...
BUILDING HIGH PRESSURE IS THEN FORECAST TO DRY THE WEATHER INTO
MONDAY...ALTHOUGH TEMPERATURES WILL REMAIN UNDER THE SEASONAL
AVERAGES.
MOISTURE STREAM VIA SW FLOW ALOFT WL INTERACT WITH AN ADVNG
TROF/FRONTAL SYSTEM LATER ON MONDAY AND INTO TUESDAY FOR THE NEXT
CHC OF PCPN. ALTHOUGH MDL DEPICTIONS DIFFER...HAVE UPPED PRECIP
PROBABILITIES TO THE LIKELY CATEGORY FOR THIS SCENARIO IN
COLLABORATION WITH THE NEIGHBORING OFFICES. CURRENTLY...THE
ACCUMULATION POTENTIAL DOES NOT LOOK SIGNIFICANT AND FORECAST SNOW
AMOUNTS WL BE IN THE SUB-ADVISORY RANGE.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
BUILDING HIGH PRES IS PROJECTED TO PRVD A DRY THURSDAY...BUT
MOIST SHRTWVS MOVING THRU SW FLOW ON THE ERN FLANK OF A CNTRL
CONUS SHOULD GENERATE PERIODIC SHSN CHCS FOR WEEKS END.
LONG TERM TEMPS WERE FORECAST AT...OR BELOW THE SEASONAL NORMS
USING TWEAKED HPC GUIDANCE.
&&
.AVIATION /08Z SUNDAY THROUGH THURSDAY/...
BLEND OF RECENT SURFACE RADAR AND SATELLITE DATA SHOW POST SYSTEM COLD
POOL MVFR STRATOCUMULUS LINGERING ACROSS THE UPPER OHIO VALLEY.
INTERMITTENT IFR LIGHT SNOW CONTINUES DUE TO PASSAGE OF AN UPPER
LEVEL TROUGH.
BLEND OF RECENT RAP NAM AND SREF MODEL OUTPUT PLUS GFS LAMP
GUIDANCE SHOW SUBSIDENCE INCREASING ALOFT DUE TO EASTBOUND HIGH
PRESSURE...WHICH WILL VERTICALLY SHRINK THE COLD LAYER UNDERNEATH.
DESPITE THIS SUBSIDENCE...THE COLD POOL MVFR STRATOCUMULUS CAN
LINGER INTO THE AFTERNOON...AND PERHAPS EARLY TONIGHT ACROSS THE
I-80 CORRIDOR. HOWEVER THE INTERMITTENT IFR LIGHT SNOW SHOULD END
BY ABOUT 15Z.
HIGH PRESSURE SUBSIDENCE SHOULD PROMOTE WIDESPREAD VFR TONIGHT.
SURFACE WINDS TODAY WILL BE FROM THE WEST AT 12 KTS WITH GUSTS UP
TO 22 KTS. WINDS TONIGHT WILL BE FROM THE SOUTHWEST AT 7 KTS.
.OUTLOOK.../MONDAY THROUGH THURSDAY/...
EXPECT VFR THROUGH MONDAY MIDDAY...THEN AN EASTBOUND COLD FRONT
WILL PROVIDE LIGHT SNOW AND IFR RESTRICTIONS LATE MONDAY AND
TUESDAY. POST SYSTEM COLD POOL MAY CAUSE LINGERING MVFR
STRATOCUMULUS WEDNESDAY AND THURSDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...WINTER STORM WARNING UNTIL 1 PM EST THIS AFTERNOON FOR MDZ001.
OH...NONE.
PA...WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR
PAZ074-076.
WV...WINTER STORM WARNING UNTIL 1 PM EST THIS AFTERNOON FOR WVZ023-
041.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1254 AM EST SUN DEC 30 2012
.SYNOPSIS...
A CROSSING UPPER LEVEL DISTURBANCE WILL SPREAD LIGHT SNOW ACROSS
THE UPPER OHIO VALLEY REGION EARLY THIS MORNING. SIGNIFICANT SNOW
ACCUMULATION WILL BE CONFINED TO THE RIDGES.
&&
.NEAR TERM /THROUGH TODAY/...
SHRTWV TROF WL CONT TO SPREAD LGT SNOW ACRS THE REGION THIS MRNG. SIGNIFICANT
ACCUMULATION WL DEPEND ON UPSLOPE ENHANCEMENT...HENCE IS CONFINED TO
THE RIDGES WHERE A WINTER WEATHER ADVISORY FOR FAYETTE AND WESTMO...AND
WINTER STORM WARNING FOR GARRETT...PRESTON...AND TUCKER COUNTIES
WILL BE MAINTAINED.
SNOW SHOWER ACTIVITY WILL GRADUALLY DIMINISH...AND CEASE
ALTOGETHER BY MIDDAY AS SBSDNC INCRS...INVERSION LEVELS DROP/MID
LVL COLD POOL WITH THE DISTURBANCE SLIDES EWD.
NEAR TERM TEMPS WERE FORECAST USING A BLEND OF SREF MEANS AND THE
LATEST LAMP GUIDANCE.
&&
.SHORT TERM /TONIGHT THROUGH WEDNESDAY/...
BUILDING HIGH PRESSURE IS THEN FORECAST TO DRY THE WEATHER INTO
MONDAY...ALTHOUGH TEMPERATURES WILL REMAIN UNDER THE SEASONAL
AVERAGES.
MOISTURE STREAM VIA SW FLOW ALOFT WL INTERACT WITH AN ADVNG
TROF/FRONTAL SYSTEM LATER ON MONDAY AND INTO TUESDAY FOR THE NEXT
CHC OF PCPN. ALTHOUGH MDL DEPICTIONS DIFFER...HAVE UPPED PRECIP
PROBABILITIES TO THE LIKELY CATEGORY FOR THIS SCENARIO IN
COLLABORATION WITH THE NEIGHBORING OFFICES. CURRENTLY...THE
ACCUMULATION POTENTIAL DOES NOT LOOK SIGNIFICANT AND FORECAST SNOW
AMOUNTS WL BE IN THE SUB-ADVISORY RANGE.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
BUILDING HIGH PRES IS PROJECTED TO PRVD A DRY THURSDAY...BUT
MOIST SHRTWVS MOVING THRU SW FLOW ON THE ERN FLANK OF A CNTRL
CONUS SHOULD GENERATE PERIODIC SHSN CHCS FOR WEEKS END.
LONG TERM TEMPS WERE FORECAST AT...OR BELOW THE SEASONAL NORMS
USING TWEAKED HPC GUIDANCE.
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
BLEND OF RECENT SURFACE RADAR AND SATELLITE DATA SHOW POST SYSTEM COLD
POOL MVFR STRATOCUMULUS LINGERING ACROSS THE UPPER OHIO VALLEY.
INTERMITTENT IFR LIGHT SNOW CONTINUES DUE TO PASSAGE OF AN UPPER
LEVEL TROUGH.
BLEND OF RECENT RAP NAM AND SREF MODEL OUTPUT PLUS GFS LAMP
GUIDANCE SHOW SUBSIDENCE INCREASING ALOFT DUE TO EASTBOUND HIGH
PRESSURE...WHICH WILL VERTICALLY SHRINK THE COLD LAYER UNDERNEATH.
DESPITE THIS SUBSIDENCE...THE COLD POOL MVFR STRATOCUMULUS CAN
LINGER INTO THE AFTERNOON...AND PERHAPS EARLY TONIGHT ACROSS THE
I-80 CORRIDOR. HOWEVER THE INTERMITTENT IFR LIGHT SNOW SHOULD END
BY ABOUT 15Z.
HIGH PRESSURE SUBSIDENCE SHOULD PROMOTE WIDESPREAD VFR TONIGHT.
SURFACE WINDS TODAY WILL BE FROM THE WEST AT 12 KTS WITH GUSTS UP
TO 22 KTS. WINDS TONIGHT WILL BE FROM THE SOUTHWEST AT 7 KTS.
.OUTLOOK.../MONDAY THROUGH THURSDAY/...
EXPECT VFR THROUGH MONDAY MIDDAY...THEN AN EASTBOUND COLD FRONT
WILL PROVIDE LIGHT SNOW AND IFR RESTRICTIONS LATE MONDAY AND
TUESDAY. POST SYSTEM COLD POOL MAY CAUSE LINGERING MVFR
STRATOCUMULUS WEDNESDAY AND THURSDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...WINTER STORM WARNING UNTIL 1 PM EST THIS AFTERNOON FOR MDZ001.
OH...NONE.
PA...WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR
PAZ074-076.
WV...WINTER STORM WARNING UNTIL 1 PM EST THIS AFTERNOON FOR WVZ023-
041.
&&
$$
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1212 AM EST SUN DEC 30 2012
.SYNOPSIS...
ISSUED AT 321 PM EST SAT DEC 29 2012
ANOTHER ROUND OF MOSTLY LIGHT SNOW WILL OCCUR OVERNIGHT. UP TO AN
INCH OR TWO OF ACCUMULATION WILL BE POSSIBLE ALONG THE LAKESHORE
NEAR SOUTH HAVEN. AFTER A RATHER DRY SUNDAY AND SUNDAY NIGHT...THE
COMING WORK WEEK WILL BE COLDER THAN NORMAL WITH SLIGHT CHANCES FOR
SNOW MAINLY NEAR THE LAKE SHORE EACH DAY.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 321 PM EST SAT DEC 29 2012
AS NOTED IN THE PREVIOUS FORECAST UPDATE DISCUSSION...WE EXPECT
A SHOT OF LAKE ENHANCED SNOW EARLY TONIGHT MAINLY SOUTH OF HOLLAND.
THE BEST TIMEFRAME LOOKS BETWEEN 10 PM AND 2 AM. MOST RECENT RUNS
OF THE RAP HAVE BACKED TOTAL ACCUMULATIONS AT SOUTH HAVEN DOWN TO AN
INCH OR LESS COMPARED TO EARLIER AMOUNTS OF 2+ INCHES. HOWEVER...
PREFER TO MATCH UP WITH SLIGHTLY HIGHER AMOUNTS ADVERTISED BY IWX TO
ACCOUNT FOR LAKE MOISTURE THAT MAY NOT BE HANDLED WELL BY THE MODELS.
OTHERWISE...FEW CHANGES WERE MADE TO THE FORECAST. DID RAISE POPS
AND SNOW AMOUNTS MONDAY AND MONDAY NIGHT OVER OUR NRN ZONES TO
ACCOUNT FOR COLD FRONT DROPPING SOUTH THROUGH THE AREA AND TO BETTER
MATCH WITH APX TO OUR NORTH.
.LONG TERM...(TUESDAY THROUGH SATURDAY)
ISSUED AT 321 PM EST SAT DEC 29 2012
THE FOCUS OF THE FORECAST CONTINUES TO BE CENTERED ON THE ARCTIC AIR
MASS THAT IS EXPECTED TO COME DOWN AND THE RESULTING LAKE EFFECT
SNOW SHOWER CHCS.
TUE AND TUE NIGHT LOOK RATHER QUIET. SOME LIGHT LAKE EFFECT WILL BE
POSSIBLE ON TUE AS WE SHOULD SEE A WEAK UPPER TROUGH MOVE BY.
SUFFICIENT INSTABILITY OVER THE LAKE WILL ALSO BE PRESENT WITH H850
TEMPS AROUND -10 TO -12C. THE LAKE EFFECT POTENTIAL WILL DIMINISH
LATE TUE AND MAINLY DRY CONDITIONS ARE EXPECTED TUE NIGHT WITH
RIDGING BUILDING IN.
WE ARE STILL EXPECTING A FAIRLY VIGOROUS UPPER TROUGH TO DROP DOWN
IN THE REGION WED-THU. THIS WILL BRING A THREAT OF SYNOPTIC SNOW
ALONG WITH SOME LAKE ENHANCEMENT/POTENTIAL AS COLDER AIR WILL FOLLOW
IN BEHIND IT. THE MODELS HAVE BEEN STRUGGLING WITH THE EXACT TRACK
WHICH WILL HAVE IMPLICATIONS ON HOW MUCH SNOW FALLS AND WHERE IT
FALLS. THE LATEST MODELS SHOW IT TRACKING NORTH OF THE AREA AND
HAVING MOST OF THE SNOW NORTH OF IT. THE FLOW IS ALSO IMPORTANT DUE
TO LAKE ENHANCEMENT POTENTIAL. FOR NOW WE HAVE A CHC OF SNOW SHOWERS
EVERYWHERE. THIS WILL HAVE TO BE FINE TUNED.
THE NOTEWORTHY CHANGE IN THE MODELS IS A TREND TOWARD A SHORTER STAY
FOR THE ARCTIC AIR. THE MODELS ARE MORE PROGRESSIVE THAN PREVIOUS
RUNS WITH THE UPPER TROUGH AND ARCTIC AIR. THIS IS LIKELY HAVING TO
DO WITH THE SPLIT FLOW THAT DEVELOPS. THE UPPER TROUGH IS EXPECTED
TO BE GONE BY THU NIGHT. THIS WOULD MEAN LESS LAKE EFFECT POTENTIAL.
BY FRI...THE AIR AT H850 IS NOT EVEN COLD ENOUGH FOR LAKE EFFECT. WE
END UP ONCE AGAIN IN NO MANS LAND BETWEEN THE JET STREAMS. THIS
WOULD BRING US SEASONABLE TEMPERATURES WITH LITTLE IF ANY PCPN CHCS.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1212 AM EST SUN DEC 30 2012
VARIABLE CONDITIONS CONTINUE ACROSS THE AREA TONIGHT WITH A BAND
OF LAKE EFFECT SNOW SHOWERS MOVING INLAND. THE SNOW SHOWERS ARE
EXPECTED TO PRODUCE MAINLY MVFR VSBY/S THE NEXT FEW HOURS...WITH
THE POTENTIAL FOR IFR VSBY/S AT AZO. THE BULK OF THE NIGHT WILL
FEATURE MVFR CEILINGS OVERSPREADING THE AREA FROM THE WEST AND
IMPROVING VSBY/S AS THE SNOW SHOWERS MOVE INLAND AND DISSIPATE.
THE MVFR CEILINGS MAY TRY TO HANG ON MUCH OF THE DAY ON SUNDAY
WITH NO RESTRICTION TO VSBY. THE CEILINGS WILL BE LAKE GENERATED.
AN IMPROVEMENT TOWARD VFR SHOULD OCCUR EITHER DURING THE
AFTERNOON OR MORE LIKELY TOWARD EVENING.
&&
.MARINE...
ISSUED AT 351 PM EST SAT DEC 29 2012
NO CHANGES WERE MADE TO THE INHERITED FORECAST. LATEST LOCAL RUN
OF THE GLERL KEEPS WAVES BELOW SMALL CRAFT CRITERIA UNTIL WELL
AFTER MIDNIGHT. THIS IS A FEW HOURS AFTER THE 10 PM OFFICIAL START
OF THE SMALL CRAFT ADVISORY. THERE MAY BE A BRIEF PERIOD OF SUB-
ADVISORY WAVES SUNDAY AFTERNOON. HOWEVER THIS WILL BE SHORT-LIVED
AS WINDS NEAR OR AT GALE FORCE ARE EXPECTED BOTH SUNDAY NIGHT AND
MONDAY.
&&
.HYDROLOGY...
ISSUED AT 321 PM EST SAT DEC 29 2012
NO HYDRO CONCERNS DUE TO VERY LITTLE QPF. RIVER ICE WILL BE LIKELY
TO DEVELOP BY THE END OF THE COMING WORK WEEK.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR
LMZ844>849.
&&
$$
SYNOPSIS...TJT
SHORT TERM...TJT
LONG TERM...NJJ
AVIATION...DUKE
HYDROLOGY...TJT
MARINE...TJT
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
1146 PM EST SAT DEC 29 2012
.AVIATION...
//DISCUSSION...
DRY AIR ADVECTION HAS ALLOWED A SIGNIFICANT CLEARING OVER THE SE MI
TERMINALS. THE LOW LEVEL FLOW WILL HOWEVER BACK TO THE
WEST-SOUTHWEST THIS MORNING. THIS WILL BRING THE LAKE STRATO CU NOW
OVER SW LOWER MI BACK INTO THE AREA. UPSTREAM OBS SUGGEST CEILINGS
WILL BE QUITE VARIABLE WITHIN THESE CLOUDS AND EXPECT THEY WILL
FLUCTUATE BETWEEN MVFR AND VFR THROUGH THE MORNING. THE FLOW WILL
BACK TOWARD THE SOUTHWEST SUN AFTERNOON. THIS ALONG WITH ANOTHER
PUSH OF DRY AIR SHOULD CLEAR THE LOW CLOUDS OUT DURING THE
AFTERNOON.
FOR DTW...THERE IS CHANCE FOR SOME ADDITIONAL FLURRIES LATE TONIGHT
AND SUN MORNING AS A MORE DIRECT WESTERLY FLOW DEVELOPS OFF LAKE MI.
//DTW THRESHOLD THREATS...
* MEDIUM CONFIDENCE CEILINGS WILL BE BELOW 5000 FT THIS MORNING.
&&
.PREV DISCUSSION...ISSUED 922 PM EST SAT DEC 29 2012
UPDATE...
SOME FAIRLY LARGE BREAKS IN THE CLOUDS HAVE DEVELOPED THIS
EVENING...WHICH WILL REQUIRE A SLIGHT DOWNWARD ADJUSTMENT TO THE
OVERNIGHT MIN TEMP FORECAST. THE LOW LEVEL FLOW WILL TURN MORE
WESTERLY OVERNIGHT...WHICH WILL BRING SOME LAKE STRATUS AND
POSSIBLE FLURRIES BACK INTO SE MI. AN UPDATE WILL BE ISSUED TO
REFLECT THESE CHANGES. THE EXETER ONT RADAR SHOWS THAT THE SNOW
SHOWERS WHICH AFFECTED THE THUMB REGION EARLIER THIS EVENING ARE
NOW WELL OVER THE LAKE THANKS TO THE BACKING FLOW.
PREV DISCUSSION...ISSUED 406 PM EST SAT DEC 29 2012
SHORT TERM...THIS EVENING AND TONIGHT
SURFACE OBSERVATIONS UPSTREAM OVER NORTHERN LAKE HURON SUPPORT THE
MAIN STRUCTURE OF LAKE HURON AGGREGATE TROUGH HAS BROKEN DOWN. HIGH
RESOLUTION MODEL DATA HAS BEEN DEPICTING A SOLUTION THAT SUPPORTED
TRACKING A MESOVORTEX OR WELL ORGANIZED LOW LEVEL CONVERGENCE BANDING
STRUCTURE INTO PORTIONS OF HURON COUNTY AND THE NORTHERN THUMB AS
THE NORTHWESTERLY FLOW BECAME DOMINANT. WITH NO REDUCTION IN SFC
VISIBILITIES EARLIER THIS AFTERNOON FOR THE UPSTREAM SHORELINE AREAS
OF NORTHERN LOWER THIS IDEA FOR A MESOLOW CAN NOW BE ABANDONED. THIS
IS IMPORTANT BECAUSE THE IDEA OF LONGER DURATION DUE TO PROPAGATION
EFFECTS CAN BE APTLY BE DISCOUNTED AS WELL.
THE LAKE EFFECT EVENT NOW ANTICIPATED WILL BE A BRIEF
ONE...RELEGATED TO DEVELOPED ACTIVITY ADVECTING THROUGH ON THE LEAD
BACKED NORTHEASTERLY PUSH...VERY MUCH OF A SQUALL NATURE. SATELLITE
IMAGERY HAS SHOWN LOW CLOUD STRATOCUMULUS AGGRESSIVELY PUSHING INTO
EASTERN HURON COUNTY/MARKED WITH A GRAVITY STRUCTURE DURING THE PAST
HOUR. KDTX/KAPX BEAMS ARE BOTH OVERSHOOTING THE ACTIVITY WITH THE
AREAS OF INTEREST AT ROUGHLY 90 NM OR APPX 10 KFT AGL ON THE .5
DEGREE. ENVIRONMENT CANADA EXETER RADAR IS IN A BETTER LOCATION AND
IS SHOWING 25-30 DBZ EXTENDING INLAND/EAST OF BAD AXE. PLACED SOME
CALLS TO FIELD REPORTS AND DID MANAGE TO GET A CREDIBLE REPORT OF .5
INCH PER ONE HALF HOUR IN PORT HOPE. HOWEVER...THE SNOW HAD ALREADY
BEEN ON THE WANE SUGGESTING A TENUOUS SETUP. VARIOUS HI RESOLUTION
FLAVORS OF NWP - 3.5KM ARW WRF - 4 KM NMM SPC WRF - 3KM HRRR AND 13
KM RAP NOW AGREE IN SWEEPING THIS LAKE EFFECT THROUGH DURING 19-22Z.
DURATION OF SNOWFALL SHOULD ONLY LAST 1-1.5 HOUR AT MOST BEFORE
PUSHING BACK INTO LAKE HURON. THEREFORE...THE FORECAST WILL CALL FOR
A CONDITIONAL...UP TO 2 INCHES FOR LOCATIONS OF HURON/SANILAC
COUNTIES EAST OF A LINE FROM BAD AXE TO SANDUSKY.
OTHERWISE...LARGE SCALE MIDLEVEL TROUGH IS NOW ADVANCING INTO THE
WESTERN PORTIONS OF LOWER MICHIGAN. THE OLD 850-700MB DEFORMATION
FORCING THAT IS A CARRYOVER FROM LAST NIGHT HAS BEEN EFFICIENT IN
GENERATING AFTERNOON LIGHT SNOW/FLURRIES HERE ACROSS MUCH OF THE
REGION. HIGHEST REFLECTIVITIES HAVE BEEN IN EXCESS OF 20 DBZ BUT IS
LACKING IN ANY BITE/MORE OF A FUNCTION OF A FEW LARGE FLAKES. NOT
EXPECTING MUCH ACCUMULATION WITH THIS BEFORE DISSIPATING.
LOWS TONIGHT ARE VERY TRICKY AND DEPENDENT ON CLOUD COVER. DID STEER
THE FORECASTED LOWS A LITTLE TOWARDS RECENT GUIDANCE...AROUND 20
DEGREES.
LONG TERM...SUNDAY THROUGH SATURDAY
QUIET WEATHER EXPECTED SUNDAY/SUNDAY NIGHT AS HIGH PRESSURE BUILDS
ACROSS THE EASTERN CONUS W/ THE NORTHERN EXTENT OF SURFACE RIDGING
PROVIDING RELATIVELY LIGHT WINDS AND PARTLY CLOUDY SKIES FOR THE
SOUTHERN GREAT LAKES. AS THE RIDGE AXIS PROGRESSES EAST OF THE AREA
ON MONDAY...CLOUDS/WINDS WILL INCREASE WITH THE APPROACH OF THE NEXT
DISTURBANCE. THIS SYSTEM WILL CROSS NORTH OF THE AREA...BUT PUSH A
COLD FRONT THROUGH THE REGION BY MONDAY NIGHT.
THE STORM SYSTEM THAT HAS BASICALLY THE ONLY POTENTIAL TO BRING
NOTEWORTHY SNOW TO THE AREA IS CURRENTLY SPINNING OVER CALIFORNIA.
OF THE 12Z MODEL SUITE...THE NAM12 IS THE ONLY MODEL TRYING TO
MAINTAIN SOME INTEGRITY TO THIS WAVE AS IT EJECTS NORTHEAST OUT OF
THE FOUR CORNERS ALONG THE MEAN CENTRAL CONUS UPPER TROUGH INTO A
LARGELY CONFLUENT UPPER FLOW OVER THE NORTHEAST QUADRANT OF THE
NATION.
IN ADDITION TO SHOWING THE STRONGEST SOLUTION FOR THIS SHORTWAVE
ITSELF...THE OTHER MAIN DIFFERENCE IS THE HANDLING OF SHORTWAVE
ENERGY DIGGING SOUTH/SOUTHEAST INTO POLAR VORTEX NEAR HUDSON BAY AS
THE NAM..THROUGH THIS PROCESS...MAINTAINS A MORE NORTHERN POSITION
TO THIS FEATURE AND ALLOWS ITS "STRONGER" WAVE TO EJECT FURTHER
NORTH INTO THE OHIO VALLEY/SOUTHERN GREAT LAKES AND BRING SEVERAL
INCHES OF SNOW TO PARTS OF LOWER MICHIGAN.
WHILE THE ARCTIC JET ENERGY THAT WILL EVENTUALLY DICTATE THE
EVOLUTION OF THE HUDSON BAY LOW AND THE STEERING OF THE SOUTHERN
STREAM WAVE HAS YET TO BE SAMPLED VERY WELL...IT IS HARD TO IGNORE
SUCH A STRONG MODEL CONSENSUS AGAINST THE NAM...WHICH CALLS FOR
STRONGER AMPLIFICATION OF THE NORTHERN STREAM OVER EASTERN CANADA.
THIS SCENARIO WILL SHUNT THE SOUTHERN SYSTEM ON A TRACK WELL SOUTH
OF THE AREA AND KEEP ANY NOTABLE PRECIPITATION CONFINED TO THE
TENNESSEE VALLEY AND POINTS SOUTH WITH IT WITH JUST SCATTERED SNOW
SHOWERS OVER LOWER MICHIGAN WITHIN THE CYCLONIC NORTHWEST FLOW AS
COLDER AIR SURGES THROUGH THE GREAT LAKES WITH THE EVOLUTION OF THIS
NORTHERN SYSTEM.
WILL MAINTAIN A FORECAST BASED ON THIS IDEA...WITH LITTLE/NO CHANCE
OF SIGNIFICANT SNOW AND ALSO A DECENT COOL DOWN AS THIS STRONG
EASTERN CANADA UPPER LOW/TROUGH ALLOWS FOR A DECENT PENETRATION OF
POLAR/MODIFIED ARCTIC AIR INTO THE REGION. SO...AFTER EDGING BACK TO
HIGH TEMPERATURES IN THE 30S ON MONDAY...20S WILL BE THE RULE MUCH
OF THE UPCOMING WEEK WITH LOWS IN THE SINGLE DIGITS/TEENS MUCH OF
THE TIME.
MARINE...
A MODEST INCREASE TO THE SURFACE PRESSURE GRADIENT COMBINED WITH
WINDS ROTATING TO A MORE ONSHORE DIRECTION WILL MAINTAIN A MODERATE
BREEZE ACROSS CENTRAL AND SOUTHERN LAKE HURON TODAY. WAVE HEIGHTS
ARE ALREADY RAMPING UP INTO THE 4 TO 7 FOOT RANGE THIS AFTERNOON.
SMALL CRAFT ADVISORIES REMAIN IN EFFECT FROM OUTER SAGINAW BAY TO
PORT HURON THROUGH TONIGHT.
A MODERATE SOUTHWEST FLOW WILL DEVELOP SUNDAY NIGHT INTO MONDAY AS
THE SURFACE PRESSURE GRADIENT TIGHTENS OVER AREA WATERS AS LOW
PRESSURE CROSSES NORTH OF THE REGION. GUSTY NORTHWEST WINDS WILL
DEVELOP BY MIDWEEK NEXT WEEK AS COLDER AIR SPREADS INTO THE GREAT
LAKES REGION IN THE WAKE OF THIS SYSTEM.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...
SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT
SANILAC...UNTIL 7 AM SUNDAY.
SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT SANILAC TO PORT
HURON...UNTIL 10 AM SUNDAY.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
AVIATION.....SC
UPDATE.......SC
SHORT TERM...CB
LONG TERM....DG
MARINE.......CB
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
323 AM CST SUN DEC 30 2012
.DISCUSSION...
FOREMOST WEATHER CONCERNS OVER THE NEXT SEVEN DAYS ARE
PRECIPITATION CHANCES TONIGHT AND WEDNESDAY...AND LOW TEMPERATURES
AND WIND CHILL VALUES FOR NEW YEARS EVE/DAY.
EARLY MORNING SURFACE ANALYSIS AND SATELLITE IMAGERY SHOW A
SURFACE RIDGE IN PLACE OVER THE FORECAST AREA. STRATUS CLOUDS ON
THE NORTHERN PERIPHERY OF THE RIDGE HAVE AFFECTED THE FAR WEST
CENTRAL WI COUNTIES OVERNIGHT...ALTHOUGH THE MAJORITY OF THE AREA
HAS EXPERIENCED MOSTLY CLEAR SKIES AND LIGHT WINDS. LIGHT FOG HAS
FORMED IN A FEW LOCATIONS...ALTHOUGH DRY AIR /SUB-ZERO DEWPOINTS/
OVER MUCH OF CWA HAS LIMITED DEVELOPMENT.
THE AFOREMENTIONED RIDGE SHIFTS EAST OF THE AREA TODAY...AND IS
REPLACED BY INCREASING SOUTHERLY LOW LEVEL FLOW AHEAD OF A MID
LEVEL TROUGH PASSING ACROSS ONTARIO. THE SURFACE FRONT ASSOCIATED
WITH SAID TROUGH PASSES ACROSS THE AREA TONIGHT INTO MONDAY. WHILE
ANY EVIDENCE OF MOISTURE/LIFT WITH THIS FEATURE IS SCANT...THERE
CONTINUES TO BE A WEAK LIFT SIGNATURE ON THE 275K ISENTROPIC
SURFACE PROGGED FROM SOUTH CENTRAL MN NORTHEAST ACROSS WEST
CENTRAL WI AS VERY MODEST MOISTURE ADVECTION ENSUES. HAVE RETAINED
A MENTION OF FREEZING DRIZZLE ROUGHLY FROM ALBERT LEA TO RED WING
TO LADYSMITH WI FOR LATE TONIGHT INTO MONDAY MORNING...WITH MODEL
SOUNDINGS CONTINUING TO DEPICT AN UNSATURATED DENDRITIC ZONE.
NEARLY STEADY TO FALLING TEMPS APPEAR TO BE THE MOST LIKELY TREND
ON MONDAY GIVEN THE TIMING OF THE FRONTAL PASSAGE.
ARCTIC AIR THEN INVADES THE UPPER MIDWEST IN THE WAKE OF THE
FRONT...WITH PREVIOUSLY FORECAST NEW YEAR/S MORNING/S LOWS OF -10
TO -20 APPEARING ON TARGET. DEPENDING ON HOW MUCH WINDS DROP OFF
WITH THE ARRIVAL OF THE RIDGE...MAY EVENTUALLY NEED A WIND CHILL
ADVISORY FOR MONDAY NIGHT INTO TUESDAY MORNING.
THE NEXT CHANCE FOR SNOWFALL ARRIVES ON WEDNESDAY INTO
THURSDAY...AS A TROUGH DROPS OUT OF SASKATCHEWAN/MANITOBA AND
CLIPS THE AREA. MODELS HAVE BEEN FAIRLY CONSISTENT WITH THIS
FEATURE...SO HAVE INTRODUCED LOW CHANCE POPS. WILL LIKELY NEED TO
INCREASE POPS MORE AS CONFIDENCE INCREASES...BUT SNOWFALL AMOUNTS
WOULD LIKELY BE RELATIVELY LOW /INCH OR LESS/ IN THIS TYPE OF
PATTERN.
TEMPERATURES GRADUALLY MODERATE INTO THE WEEKEND WITH HIGHS IN THE
LOW/MID 20S.
&&
.AVIATION.../06Z TAF ISSUANCE/
LARGE AREA OF MVFR CEILINGS MOVING SLOWLY EAST THROUGH WESTERN
WISCONSIN. LATEST RAP AND SATELLITE TRENDS SUGGEST IT SHOULD EXIT
KEAU AROUND 08Z. BELIEVE SKY SHOULD BE MOSTLY CLEAR WITH VSBY
ABOVE 5SM THROUGH THE NIGHT...WITH ANY FOG BEING RATHER LOCALIZED.
SURFACE RIDGE OVER MN AT THIS TIME...BUT IT SHOULD BE OVER WESTERN
WISC BY 12Z. THIS WILL ALLOW SOUTH WINDS TO PICK UP ACROSS WESTERN
AND CENTRAL MN. LARGE SWATH OF MID/HIGH CLOUDS ALSO MOVING IN FROM
THE DAKOTAS. SO BETWEEN THE STEADY WIND AND THE CLOUD...THINK FOG
WILL NOT BE WIDESPREAD. WESTERN WISC IS THE AREA TO WATCH FOR
MORE FOG/STRATUS WITH RIDGE AXIS. HAVE ADDED SOME 4-5SM VSBY IN
FOG AT KEAU AND KRNH. INCOMING FRONT LOOKS TO REACH KAXN LATE
SUNDAY AFTERNOON WITH MVFR STRATUS...THEN PROGRESS SOUTHEAST WITH
MVFR STRATUS SPREADING OVER THE REGION.
KMSP...SMALL POTENTIAL FOR MVFR CEILING/VSBY TO REDEVELOP AFTER
06Z. IF THAT HAPPENS...CEILINGS WOULD PROBABLY BE AROUND
1200 FT AGL ALONG WITH VSBY AROUND 5SM. BUT THIS SEEMS UNLIKELY AS
HIGH CLOUDS APPROACH. SUNDAY WILL FEATURE LIGHT SOUTHERLY WINDS
WITH NEXT ARCTIC FRONT ARRIVING AROUND 03Z MONDAY WITH SOME MVFR
CEILINGS AROUND 2000 FT AGL.
/OUTLOOK FOR KMSP/
MON...VFR. WINDS NW 10-15 KTS.
TUE...VFR. WINDS SW 5-10 KTS.
WED...VFR. SLIGHT CHANCE OF MVFR AND LIGHT SNOW. WINDS NW 5-10
KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
LS/TDK
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1035 PM CST SAT DEC 29 2012
.UPDATE...
UPDATED FOR AVIATION DISCUSSION BELOW.
&&
.DISCUSSION...
/ISSUED 406 PM CST SAT DEC 29 2012/
OVERVIEW...MOSTLY CLEAR AND COLD TONIGHT WITH CONTINUING COLD
TEMPERATURES THROUGH THE NEW YEAR. THE NEXT CHANCE FOR LIGHT
PRECIP ARRIVES SUNDAY NIGHT INTO MONDAY MORNING WITH A SMALL
CHANCE FOR LIGHT FREEZING DRIZZLE IN SOUTHEAST MN AND PORTIONS OF
WESTERN WI. THE NEXT CHANCE FOR LIGHT SNOW WILL BE WEDNESDAY INTO
THURSDAY. ALTHOUGH...THERE IS STILL A LOT OF UNCERTAINTY WITH THIS
SYSTEM AND IT DOESN`T LOOK PARTICULARLY STRONG AT THIS TIME. NEW
YEARS EVE LOOKS LIKE THE COLDEST NIGHT OF THE WINTER SEASON SO FAR
IN MANY LOCATIONS.
FLOW BECOMES ANTICYCLONIC TONIGHT AS TROUGH SUPPLYING ALL THE SNOW
TO THE EAST COAST CONTINUES ITS EASTWARD TRACK. TROUGH DROPPING
SOUTH OUT OF THE INTERIOR OF CANADA MOVES ACROSS LAKE WINNIPEG BY
THIS TIME TOMORROW. LIGHT SNOW LOOKS POSSIBLE IN FAR NORTHERN
MN TOMORROW...BUT EVEN WITH A COUPLE MORE SUBTLE SHORTWAVES
TRAILING THIS FEATURE AND A SLIGHT SURFACE REFLECTION/COLD
FRONT...MOST OF MN/WI WILL REMAIN DRY. THERE ISN`T MUCH
FORCING/FGEN...BUT THERE IS LOW LEVEL WARM AIR ADVECTION AND A
MODEST AMOUNT OF MOISTURE TRANSPORT TOMORROW NIGHT. WE WARM TEMPS
TOMORROW TO REFLECT OUR THINKING OF MOSTLY CLEAR SKIES AND
SOUTHWEST FLOW. THE GFS/NAM SUGGEST SATURATION FROM ABOUT 900-925
MB TO THE SFC. CHECKING OUT THE ISENTROPIC SURFACES...A DECENT
AMOUNT OF UPGLIDE ON THE 270-280 ISENTROPIC SURFACES...WHICH WOULD
BE IN THE SATURATION. SOUNDINGS STAY MOSTLY ABOVE -10 C...KEEPING
ICE OUT OF THE CLOUD...AND MAKING FREEZING DRIZZLE THE MORE
PROBABLE PREIP TYPE. WE ADDED PATCHY FREEZING DRIZZLE TO THE
FORECAST...BUT LEFT POPS BELOW 15% AT THIS TIME. BETTER SATURATION
LOOKS TO OCCUR IN SOUTHEAST MN AND PORTIONS OF SOUTHWEST/WEST
CENTRAL WI.
AFTER SUNDAY NIGHT...MUCH OF THE COUNTRY WILL SEE A STEADY SUPPLY
OF DRY CONTINENTAL AIR...WITH TRUE ARCTIC AIR INTRUDING INTO THE
NORTHERN PLAINS AND UPPER MISSISSIPPI RIVER VALLEY EARLY THIS
WEEK. THE MODEL GUIDANCE IS STILL QUITE VARIED IN FORECAST LOWS
NEW YEARS EVE. THE GEM/EC/NAM SUGGEST QUITE A FEW LOCATIONS WILL BE
-10 TO -20 BELOW BY TUESDAY MORNING. THE EARLY MORNING FORECAST
/PREVIOUSLY ISSUED/ DID A GOOD JOB DRIVING TEMPS DOWN BEHIND THE
ARCTIC BOUNDARY. SO...REALLY DIDN`T CHANGE TEMPS A WHOLE LOT FROM
WHAT WAS PREVIOUSLY FORECASTED.
ALL BUT THE GEM NOW FORECAST MOST OF THE LIGHT SNOW ACROSS
CENTRAL/NORTHERN MN AND NORTHERN WI WEDNESDAY NIGHT AND
THURSDAY...OR NOT AT ALL /GFS/. THE 29.12Z EC HAS TRENDED TOWARD A
DEEPER SURFACE LOW BUT ALSO SHIFTED ABOUT A HALF STATE TO THE NORTH.
THIS IS A CLIPPER SYSTEM WITH LIGHT QPF AND HIGH SNOW RATIOS...BUT
THERE IS STILL TOO MUCH UNCERTAINTY TO INCLUDE MUCH HIGHER THAN
SLIGHT CHANCE POPS AT THIS POINT.
&&
.AVIATION.../06Z TAF ISSUANCE/
LARGE AREA OF MVFR CEILINGS MOVING SLOWLY EAST THROUGH WESTERN
WISCONSIN. LATEST RAP AND SATELLITE TRENDS SUGGEST IT SHOULD EXIT
KEAU AROUND 08Z. BELIEVE SKY SHOULD BE MOSTLY CLEAR WITH VSBY
ABOVE 5SM THROUGH THE NIGHT...WITH ANY FOG BEING RATHER LOCALIZED.
SURFACE RIDGE OVER MN AT THIS TIME...BUT IT SHOULD BE OVER WESTERN
WISC BY 12Z. THIS WILL ALLOW SOUTH WINDS TO PICK UP ACROSS WESTERN
AND CENTRAL MN. LARGE SWATH OF MID/HIGH CLOUDS ALSO MOVING IN FROM
THE DAKOTAS. SO BETWEEN THE STEADY WIND AND THE CLOUD...THINK FOG
WILL NOT BE WIDESPREAD. WESTERN WISC IS THE AREA TO WATCH FOR
MORE FOG/STRATUS WITH RIDGE AXIS. HAVE ADDED SOME 4-5SM VSBY IN
FOG AT KEAU AND KRNH. INCOMING FRONT LOOKS TO REACH KAXN LATE
SUNDAY AFTERNOON WITH MVFR STRATUS...THEN PROGRESS SOUTHEAST WITH
MVFR STRATUS SPREADING OVER THE REGION.
KMSP...SMALL POTENTIAL FOR MVFR CEILING/VSBY TO REDEVELOP AFTER
06Z. IF THAT HAPPENS...CEILINGS WOULD PROBABLY BE AROUND
1200 FT AGL ALONG WITH VSBY AROUND 5SM. BUT THIS SEEMS UNLIKELY AS
HIGH CLOUDS APPROACH. SUNDAY WILL FEATURE LIGHT SOUTHERLY WINDS
WITH NEXT ARCTIC FRONT ARRIVING AROUND 03Z MONDAY WITH SOME MVFR
CEILINGS AROUND 2000 FT AGL.
/OUTLOOK FOR KMSP/
MON...VFR. WINDS NW 10-15 KTS.
TUE...VFR. WINDS SW 5-10 KTS.
WED...VFR. SLIGHT CHANCE OF MVFR AND LIGHT SNOW. WINDS NW 5-10
KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
CLF/TDK
AREA FORECAST DISCUSSION
NWS PORTLAND OR
823 PM PST SAT DEC 29 2012
.SYNOPSIS...A WEAK DISTURBANCE IS MOVING SOUTH THROUGH THE FORECAST
AREA THIS EVENING. DRIER WEATHER IS EXPECTED LATE TONIGHT AND SUNDAY
AS AN UPPER LEVEL RIDGE BUILDS IN. A SPLITTING TROUGH WILL APPROACH
MONDAY FOLLOWED BY ANOTHER UPPER RIDGE TUESDAY. OFFSHORE GRADIENTS
WILL GRADUALLY INTENSIFY NEXT WEEK RESULTING IN AN EXTENDED PERIOD OF
EAST WIND THROUGH THE COLUMBIA RIVER GORGE.
&&
.SHORT TERM...SATELLITE IMAGERY SHOWS A WEAK DISTURBANCE ENHANCING
THE CLOUDS OVER SOUTHWEST WASHINGTON/NORTHWEST OREGON THIS EVENING.
THIS FEATURE IS MOVING SOUTHWARD THROUGH THE AREA THIS EVENING.
DOPPLER RADAR AND SURFACE OBSERVATIONS SHOWS VERY LIGHT SHOWERS OVER
THE NORTHERN HALF OF THE AREA. BY 12Z SUN HIGH PRESSURE CENTERED AT
130W STRENGTHENS IN RESPONSE TO THE DEEP LOW OUT AROUND 150W. EXPECT
CLOUDS TO DIMINISH FROM THE NORTH OVERNIGHT.
SUNDAY WILL BE DRY AS THE UPPER LEVEL RIDGE AXIS GETS CLOSER TO THE
COAST. EXPECT WEAK OFFSHORE SURFACE FLOW TO CONTINUE SUNDAY. GRADIENT
SHOULD INCREASE A LITTLE MORE SUN NIGHT WITH WIDESPREAD FREEZING
TEMPS. SUN NIGHT SHOULD BE THE COLDEST NIGHT OF THE SEASON SO FAR IN
MANY AREAS. MODELS GOING WITH UPPER TEENS IN SPOTS LIKE KHIO AND 20
AT KEUG. CLEAR SKIES AND COLD TEMPERATURES SHOULD PRODUCE PATCHY
FREEZING FOG IN THE INTERIOR VALLEYS SUN NIGHT. HOWEVER...AIR MASS
MAY BE COLD AND DRY ENOUGH TO INHIBIT MUCH FOG FORMATION.
ANOTHER SPLITTING TROUGH APPROACHES THE COAST MON
MORNING...STRETCHING APART JUST OFFSHORE MON...WITH THE MAIN ENERGY
DIVING SOUTH ALONG THE NRN CA COAST. PRECIP SEEMS LIMITED TO THE
COASTAL WATERS AND COASTAL STRIP. HIGH PRESSURE ALOFT STRENGTHENS
AGAIN MON NIGHT AS DOES THE OFFSHORE SURFACE GRADIENT. EXPECT ANOTHER
COLD NIGHT WITH SOME VALLEY LOCATIONS GETTING CLOSE TO 20 DEGREES.
LIKENS
.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...UPPER LEVEL
RIDGE IN PLACE TUESDAY AND WEDNESDAY WILL PROVIDE DRY
WEATHER...THOUGH FAVORABLE CONDITIONS FOR VALLEY FOG BOTH MORNINGS.
THE EXCEPTION WILL BE ON THE WEST SIDE OF THE GORGE WHERE EASTERLY
WINDS SHOULD STAY HIGH ENOUGH TO PREVENT ANY FOG FORMATION. BY LATE
WEDNESDAY MODEL AGREEMENT DEGRADES AS A CUT OFF LOW PRESSURE SYSTEM
MOVES TOWARD THE PAC NW...AND THE MODELS STRUGGLE WITH WHERE THIS
FEATURE WILL ULTIMATELY GO. CURRENTLY THEY ARE IN GOOD AGREEMENT ON
TIMING...AND DEPICT THE LOW MOVING ONSHORE LATE THURSDAY.
HOWEVER...THE MODELS BRING IT INLAND ANYWHERE FROM NORTHERN
CALIFORNIA TO NORTHERN WASHINGTON. DUE TO THIS UNCERTAINTY...DID NOT
MAKE MAJOR CHANGES TO THE PREVIOUS FORECAST...BUT DID TREND TOWARD
THE ECMWF MODEL PER NATIONAL AND INTERSITE COORDINATION/MODEL
PREFERENCE. THE ECMWF SOLUTION IS THE MORE SOUTHERLY TRACK...BRINGING
THE LOW ONSHORE IN NORTHERN CALIFORNIA AND KEEPING THE PAC NW FAIRLY
DRY THROUGH THE EXTENDED PERIOD. TEMPERATURES LOOK TO BE NEAR NORMAL
FROM THURSDAY ONWARD. BURGESS
&&
.AVIATION....SHORT WAVE DROPPING SOUTH OUT OF WESTERN WA BRINGING
SHOWERS MAINLY OVER THE NORTHERN INLAND AREAS THIS EVENING.
RADAR LOOP SHOWS TAIL END OF SHOWERS JUST ABOUT TO MOVE OUT OF SW
WA INTO OREGON. SATELLITE SHOW A SIMILAR TREND WITH COLDER CLOUD
TOPS MOVING OUT OF SW WA TO REVEAL LOWER CLOUDS BELOW. SFC OBS
INDICATING LOW MVFR TO IFR CONDITIONS WITH A FEW SHOWERS STILL COMING
FROM THE LOWER CLOUD LAYER. TAKING A LOOKS AT NAM BUFR SOUNDINGS IT
WILL TAKE A WHILE FOR CONDITIONS TO IMPROVE...ESPECIALLY INLAND.
THE 00Z NAM BUFR SOUNDINGS KEEP IFR TO LOW MVFR CIGS AT INLAND TAF
SITES THROUGH ABOUT 14Z-18Z SUN. THE 00Z RUC SOUNDINGS SUGGEST MORE
OF A LOW MVFR THROUGH THAT SAME TIME PERIOD AND WILL LIKELY TREND
FCST TOWARD THE RUC SOLN. AIR MASS DRYING AS OFFSHORE FLOW
STRENGTHENS FOR MAINLY VFR CONDITIONS LATER SUN MORNING AND
AFTERNOON.
KPDX AND APPROACHES...MVFR CIGS PREVAILING TONIGHT WITH IFR CIGS
POSSIBLE THROUGH ABOUT 14Z. CONFIDENCE NOT HIGH ENOUGH TO INCLUDE
IFR IN THE 06Z TAF PACKAGE BUT WILL INCLUDE A SCATTERED LAYER FOR
THE OVERNIGHT HOURS.
&&
.MARINE...LONG-PERIOD SWELL TRAIN OVER THE COASTAL WATERS IS
BEGINNING TO DIMINISH AND WILL DROP BELOW 10 FT AFTER MIDNIGHT.
WEAK HIGH PRES BUILDS OFFSHORE THROUGH EARLY SUNDAY...BUT THAT IS
SHORT LIVED AS ANOTHER WEAKENING FRONT APPROACHES THE WATERS SUN
NIGHT INTO MONDAY. HIGH PRES RETURNS AGAIN TUES BEFORE ANOTHER
SPLITTING SYSTEM ARRIVES LATE WED. NO REAL WIND CONCERNS WITH
THESE FRONTS...THOUGH BEHIND EACH SUBSEQUENT FRONT SWELL PICKS
BACK UP INTO THE TEENS. TODD
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 3 AM PST
SUNDAY FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE
OR OUT 60 NM.
SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL
8 AM PST SUNDAY.
&&
$$
MORE WEATHER INFORMATION ONLINE AT...HTTP://WEATHER.GOV/PORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
802 AM EST SUN DEC 30 2012
.SYNOPSIS...
BRISK WESTERLY WINDS WILL PROVIDE COLD TEMPERATURES
ACROSS THE UPPER OHIO VALLEY WITH SCATTERED SNOW SHOWERS ENDING BY
AFTERNOON EXCEPT PERHAPS NEAR THE MOUNTAINS. PASSING HIGH PRESSURE
WILL PROMOTE DRY CONDITIONS TONIGHT AND MONDAY MORNING. THEN AN
EASTBOUND COLD FRONT WILL BRING IN SNOW SHOWERS FOR THE NEW YEAR.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
REGIONAL RADAR MOSAIC ILLUSTRATES SHSN DROPPING SE FROM LAKE ERIE.
VSBYS ARE MAINLY ABOVE 2SM IN THE HEAVIEST SNOW SHOWERS...SO ACCUMULATING
SNOW IS OVER WITH SAVE FOR THE RIDGES THAT ARE UNDER A
WARNING...WHERE ANOTHER INCH OR TWO OF DAYTIME ACCUMULATION MAY
OCCUR.
LATEST RAP ANALYSIS HAS H8 THERMAL TROUGH LIFTING BY 21Z ALLOWING
FOR WINDS TO BECOME SOUTHWEST SHUTTING OFF THE LAKE EFFECT AND
TERRAIN INDUCED SNOWFALL. STILL ANTICIPATE TO SEE SUNSHINE LATER
THIS AFTERNOON FOR AREAS WEST OF I-79 AS THE COLUMN DRIES OUT AND
WAA ENSUES.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
BUILDING HIGH PRESSURE IS THEN FORECAST TO DRY THE WEATHER INTO
MONDAY...ALTHOUGH TEMPERATURES WILL REMAIN COLDER THAN SEASONAL
AVERAGES.
MOISTURE STREAM VIA SW FLOW ALOFT WL INTERACT WITH AN ADVNG
TROF/FRONTAL SYSTEM LATER ON MONDAY AND INTO TUESDAY FOR THE NEXT
CHC OF PCPN. ALTHOUGH MDL DEPICTIONS DIFFER...HAVE UPPED PRECIP
PROBABILITIES TO THE LIKELY CATEGORY FOR THIS SCENARIO IN
COLLABORATION WITH THE NEIGHBORING OFFICES. CURRENTLY...THE
ACCUMULATION POTENTIAL DOES NOT LOOK SIGNIFICANT AND FORECAST SNOW
AMOUNTS WL BE IN THE SUB-ADVISORY RANGE.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
BUILDING HIGH PRES IS PROJECTED TO PRVD A DRY THURSDAY...BUT
MOIST SHRTWVS MOVING THRU SW FLOW ON THE ERN FLANK OF A CNTRL
CONUS SHOULD GENERATE PERIODIC SHSN CHCS FOR WEEKS END.
LONG TERM TEMPS WERE FORECAST AT...OR BELOW THE SEASONAL NORMS
USING TWEAKED HPC GUIDANCE.
&&
.AVIATION /13Z SUNDAY THROUGH THURSDAY/...
WIDESPREAD MVFR CIGS WITH VFR VSBYS ARE THE DOMINANT THEME THRU
EARLY AFTN. VIS COULD DROP TO MVFR IN A SHSN ESP AT FKL/DUJ...BUT
THERE IS AN IMPROVING TREND AS WINDS SHIFT SW ENDING LAKE EFFECT
SNOW SHOWERS. LOW LEVEL MOISTURE EXITS FROM W TO E AFT 20Z ALLOWING
VFR TO RETURN TO ALL TERMINALS BY 0Z.
.OUTLOOK.../MONDAY THROUGH THURSDAY/...
IFR RESTRICTIONS ARE LIKELY MONDAY NIGHT INTO TUESDAY. CONDITIONS
IMPROVE TO MVFR WED AND THURSDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...WINTER STORM WARNING UNTIL 1 PM EST THIS AFTERNOON FOR MDZ001.
OH...NONE.
PA...WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR
PAZ074-076.
WV...WINTER STORM WARNING UNTIL 1 PM EST THIS AFTERNOON FOR WVZ023-
041.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
635 AM EST SUN DEC 30 2012
.SYNOPSIS...
BRISK WESTERLY WINDS WILL PROVIDE COLD TEMPERATURES
ACROSS THE UPPER OHIO VALLEY WITH SCATTERED SNOW SHOWERS ENDING BY
AFTERNOON EXCEPT PERHAPS NEAR THE MOUNTAINS. PASSING HIGH PRESSURE
WILL PROMOTE DRY CONDITIONS TONIGHT AND MONDAY MORNING. THEN AN
EASTBOUND COLD FRONT WILL BRING IN SNOW SHOWERS FOR THE NEW YEAR.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
RECENT SATELLITE DATA SHOW CLOUD TOPS WARMING WEST TO EAST ACROSS
THE UPPER OHIO VALLEY AS THE UPPER LEVEL TROUGH EXITS EAST.
CORRESPONDINGLY RADAR DATA SHOWS SNOW SHOWERS ENDING WEST TO EAST
ALTHOUGH STEADY SNOW SHOWERS APPEAR TO BE CONTINUING NEAR THE
WV-MD MOUNTAINS AND PA LAUREL HIGHLANDS...AS BRISK WESTERLY WINDS
ARE PROVIDING OROGRAPHIC LIFT. SO HAVE MAINTAINED WINTER WEATHER
HEADLINES FOR THESE MOUNTAINOUS AREAS.
SURFACE DATA AND RECENT NAM MODEL PROFILES SHOW WINDS CAN GUST TO
30 TO 40 MPH INTO AFTERNOON NEAR THE MOUNTAINS. ELSEWHERE GUSTS
WILL BE UP TO 25 MPH.
FORECASTED THE TEMPERATURE CLIMB TODAY TO BE NO MORE THAN A COUPLE
DEGREES...WHICH IS SUPPORTED BY RECENT GFS LAMP...NAM AND GFS
MOS...AND RAP MODEL OUTPUT.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
BUILDING HIGH PRESSURE IS THEN FORECAST TO DRY THE WEATHER INTO
MONDAY...ALTHOUGH TEMPERATURES WILL REMAIN COLDER THAN SEASONAL
AVERAGES.
MOISTURE STREAM VIA SW FLOW ALOFT WL INTERACT WITH AN ADVNG
TROF/FRONTAL SYSTEM LATER ON MONDAY AND INTO TUESDAY FOR THE NEXT
CHC OF PCPN. ALTHOUGH MDL DEPICTIONS DIFFER...HAVE UPPED PRECIP
PROBABILITIES TO THE LIKELY CATEGORY FOR THIS SCENARIO IN
COLLABORATION WITH THE NEIGHBORING OFFICES. CURRENTLY...THE
ACCUMULATION POTENTIAL DOES NOT LOOK SIGNIFICANT AND FORECAST SNOW
AMOUNTS WL BE IN THE SUB-ADVISORY RANGE.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
BUILDING HIGH PRES IS PROJECTED TO PRVD A DRY THURSDAY...BUT
MOIST SHRTWVS MOVING THRU SW FLOW ON THE ERN FLANK OF A CNTRL
CONUS SHOULD GENERATE PERIODIC SHSN CHCS FOR WEEKS END.
LONG TERM TEMPS WERE FORECAST AT...OR BELOW THE SEASONAL NORMS
USING TWEAKED HPC GUIDANCE.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
WIDESPREAD MVFR CIGS WITH VFR VSBYS ARE THE DOMINANT THEME THRU
EARLY AFTN. VIS COULD DROP TO MVFR IN A SHSN ESP AT FKL/DUJ...BUT
THERE IS AN IMPROVING TREND AS WINDS SHIFT SW ENDING LAKE EFFECT
SNOW SHOWERS. LOW LEVEL MOISTURE EXITS FROM W TO E AFT 20Z ALLOWING
VFR TO RETURN TO ALL TERMINALS BY 0Z.
.OUTLOOK.../MONDAY THROUGH THURSDAY/...
IFR RESTRICTIONS ARE LIKELY MONDAY NIGHT INTO TUESDAY. CONDITIONS
IMPROVE TO MVFR WED AND THURSDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...WINTER STORM WARNING UNTIL 1 PM EST THIS AFTERNOON FOR MDZ001.
OH...NONE.
PA...WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR
PAZ074-076.
WV...WINTER STORM WARNING UNTIL 1 PM EST THIS AFTERNOON FOR WVZ023-
041.
&&
$$
AVIATION...98
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
516 AM EST SUN DEC 30 2012
.SYNOPSIS...BRISK WESTERLY WINDS WILL PROVIDE COLD TEMPERATURES
ACROSS THE UPPER OHIO VALLEY WITH SCATTERED SNOW SHOWERS ENDING BY
AFTERNOON EXCEPT PERHAPS NEAR THE MOUNTAINS. PASSING HIGH PRESSURE
WILL PROMOTE DRY CONDITIONS TONIGHT AND MONDAY MORNING. THEN AN
EASTBOUND COLD FRONT WILL BRING IN SNOW SHOWERS FOR THE NEW YEAR.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
RECENT SATELLITE DATA SHOW CLOUD TOPS WARMING WEST TO EAST ACROSS
THE UPPER OHIO VALLEY AS THE UPPER LEVEL TROUGH EXITS EAST.
CORRESPONDINGLY RADAR DATA SHOWS SNOW SHOWERS ENDING WEST TO EAST
ALTHOUGH STEADY SNOW SHOWERS APPEAR TO BE CONTINUING NEAR THE
WV-MD MOUNTAINS AND PA LAUREL HIGHLANDS...AS BRISK WESTERLY WINDS
ARE PROVIDING OROGRAPHIC LIFT. SO HAVE MAINTAINED WINTER WEATHER
HEADLINES FOR THESE MOUNTAINOUS AREAS.
SURFACE DATA AND RECENT NAM MODEL PROFILES SHOW WINDS CAN GUST TO
30 TO 40 MPH INTO AFTERNOON NEAR THE MOUNTAINS. ELSEWHERE GUSTS
WILL BE UP TO 25 MPH.
FORECASTED THE TEMPERATURE CLIMB TODAY TO BE NO MORE THAN A COUPLE
DEGREES...WHICH IS SUPPORTED BY RECENT GFS LAMP...NAM AND GFS
MOS...AND RAP MODEL OUTPUT.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
BUILDING HIGH PRESSURE IS THEN FORECAST TO DRY THE WEATHER INTO
MONDAY...ALTHOUGH TEMPERATURES WILL REMAIN COLDER THAN SEASONAL
AVERAGES.
MOISTURE STREAM VIA SW FLOW ALOFT WL INTERACT WITH AN ADVNG
TROF/FRONTAL SYSTEM LATER ON MONDAY AND INTO TUESDAY FOR THE NEXT
CHC OF PCPN. ALTHOUGH MDL DEPICTIONS DIFFER...HAVE UPPED PRECIP
PROBABILITIES TO THE LIKELY CATEGORY FOR THIS SCENARIO IN
COLLABORATION WITH THE NEIGHBORING OFFICES. CURRENTLY...THE
ACCUMULATION POTENTIAL DOES NOT LOOK SIGNIFICANT AND FORECAST SNOW
AMOUNTS WL BE IN THE SUB-ADVISORY RANGE.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
BUILDING HIGH PRES IS PROJECTED TO PRVD A DRY THURSDAY...BUT
MOIST SHRTWVS MOVING THRU SW FLOW ON THE ERN FLANK OF A CNTRL
CONUS SHOULD GENERATE PERIODIC SHSN CHCS FOR WEEKS END.
LONG TERM TEMPS WERE FORECAST AT...OR BELOW THE SEASONAL NORMS
USING TWEAKED HPC GUIDANCE.
&&
.AVIATION /10Z SUNDAY THROUGH THURSDAY/...
BLEND OF RECENT SURFACE RADAR AND SATELLITE DATA...COUPLED WITH RECENT
RAP NAM AND SREF MODEL OUTPUT PLUS GFS LAMP GUIDANCE...SHOW POST
SYSTEM COLD POOL MVFR STRATOCUMULUS LINGERING ACROSS THE UPPER
OHIO VALLEY INTO AFTERNOON...AND PERHAPS EARLY TONIGHT ACROSS THE
I-80 CORRIDOR.
HOWEVER MOST OF THE INTERMITTENT IFR LIGHT SNOW...ASSOCIATED WITH
AN EASTBOUND UPPER LEVEL TROUGH HAS ENDED. THE IFR LIGHT SNOW
NORTH AND NEAR THE MOUNTAINS SHOULD LIKEWISE END BEFORE 17Z.
HIGH PRESSURE SUBSIDENCE SHOULD PROMOTE WIDESPREAD VFR TONIGHT.
SURFACE WINDS TODAY WILL BE FROM THE WEST AT 12 KTS WITH GUSTS UP
TO 22 KTS. WINDS TONIGHT WILL BE FROM THE SOUTHWEST AT 7 KTS.
.OUTLOOK.../MONDAY THROUGH THURSDAY/...
EXPECT VFR THROUGH MONDAY MIDDAY...THEN AN EASTBOUND COLD FRONT
WILL PROVIDE LIGHT SNOW AND IFR RESTRICTIONS LATE MONDAY AND
TUESDAY. POST SYSTEM COLD POOL MAY CAUSE LINGERING MVFR
STRATOCUMULUS WEDNESDAY AND THURSDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...WINTER STORM WARNING UNTIL 1 PM EST THIS AFTERNOON FOR MDZ001.
OH...NONE.
PA...WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR
PAZ074-076.
WV...WINTER STORM WARNING UNTIL 1 PM EST THIS AFTERNOON FOR WVZ023-
041.
&&
$$
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1032 AM EST SUN DEC 30 2012
.SYNOPSIS...
NORTHWEST FLOW WILL DOMINATE THE WEATHER PATTERN FOR THE NEXT
WEEK. THIS WILL CREATE A PROLONGED PERIOD OF COLDER THAN NORMAL
TEMPERATURES...BUT ALSO KEEP SIGNIFICANT STORMINESS CONFINED TO
SOUTH OF THE REGION.
&&
.NEAR TERM /UNTIL 7 PM THIS EVENING/...
SNOW SHOWERS CONTINUE OVER CENTRAL PENNSYLVANIA. EAST OF THE
HIGHER TERRAIN THEY MAINLY PRODUCE A BRIEF DUSTING OF SNOW. THERE
HAS BEEN A PERSISTENT NW TO SE BAND THAT HAS EXTENDED THROUGH
STATE COLLEGE AT TIMES...BUT RECENTLY THE HIGHER ECHOES HAVE
DRIFTED NORTH. THIS FEATURE HAS PRODUCED LIGHT SNOW SHOWERS.
THERE IS STILL SOME ON GOING SNOW IN THE SW MOUNTAINS AND WILL LET
THE ADVISORY FOR 3-5 INCHES OF SNOW EXPIRE AT 18Z AS SNOW
DIMINISHES DURING THE DAY AND ACCUMULATIONS DIMINISH TOO.
STRONG WINDS AT 850 HPA...OVER 50 KTS AND A FAIRLY GOOD PRESSURE
RISE-FALL COUPLET IN 6 HOUR NAM12 AND RUC13 HAVE FAVORED A WIND
ADVISORY. IN WESTERN PA WINDS OVER 40 KTS SHOULD BE CONFINED TO
ABOUT ABOVE ABOUT 1800 FT. SOME STRONGER WINDS WITH DOWN-SLOPE
EFFECT IN SOUTHERN PA POSSIBLE TOO. GUST ALREADY IN MID-30KT RANGE
IN LOWER SUSQUEHANNA VALLEY. PUT ADVISORY ACROSS ALL OF SOUTHERN
TIER TO INCLUDE YORK-HARRISBURG AND LANCASTER AREAS. SHOULD BE
OVER LATE AFTERNOON WITH INCREASING STABILITY.
&&
.SHORT TERM /7 PM THIS EVENING THROUGH TUESDAY/...
SNOW SUBSIDES IN WEST AND WINDS SLOWLY ABATE SUNDAY NIGHT. THERE
ARE HINTS OF SOME LIGHT SNOW MOVING INTO THE WESTERN AREAS LATE IN
THE AFTERNOON OR EVENING NEW YEARS EVE. AS STATE IN PREVIOUS
SHIFTS DISCUSSION...
PREVIOUS DISCUSSION....WARM ADVECTION TONIGHT WILL TRY TO CLEAR OUT THE
SKIES...BUT MESO MDLS STILL PRODUCE MEAGER QPF IN THE FAR NW.
THUS...SCT/ISOLD SHSN MAY CONTINUE FOR THE FIRST HALF OF THE
NIGHT. CLOUDS WILL BE TOUGH TO CLEAR OVER THE NRN HALF OF THE
AREA...AND HIGH CLOUDS WILL START TO ARRIVE FROM THE WEST BY
MONDAY MORNING. JET STREAM BRIEFLY RIDGES N OF THE AREA TONIGHT
AND MONDAY...BUT AN INCREASE IN SPEED WILL OCCUR MONDAY OVER THE
OHIO VALLEY AND SPREAD ACROSS THE STATE MON NIGHT. THIS WILL
TRANSPORT A LITTLE MOISTURE UP OVER THE SFC/UPPER RIDGE...BUT NOT
MUCH AT ALL. WESTERLY/UPSLOPE FLOW WILL HELP ADD LOW-LEVEL LIFT.
THE QPF GENERATED BY ALL THE MODELS AND IN THE SREF PLUMES IS LESS
THAN A TENTH - EVEN IN THOSE UPSLOPE AREAS. SO...WHILE VERY LIGHT
SNOW IS LIKELY IN THE WEST NEW YEARS EVE/NIGHT DUE TO THE
PERSISTENT CONSENSUS AMONG THE MDLS...THE ACCUMS WILL BE ALMOST
NIL. DRYING ON THE NWRLY WINDS AND BEHIND THE STRENGTHENING JET
STREAK WILL DECREASE THE POPS ON TUES...BUT -14C AIR CROSSING THE
LAKES WILL GENERATE SOME LAKE EFFECT SHSN DOWNWIND.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
LATEST MED RANGE GUID BACKS OFF ON THE MAGNITUDE/COLDNESS OF THE
AIR MASS MOVING INTO THE NERN U.S. THIS WEEK. THUS...HAVE BUMPED
UP THE TEMPS SLIGHTLY FOR THE LONG TERM. BUT THE NW FLOW
CONTINUES...AND NOTHING ELSE WAS CHANGED WITH THE OVERNIGHT PKG.
PREV DISC FOLLOWS...
LAKE ENHANCED BANDS SHOULD CONTINUE THROUGH WEDNESDAY
MORNING...AND PERHAPS WEDNESDAY AFTERNOON. A FEW NORTHERN STREAM
FEATURES WILL CROSS THE LOWER GREAT LAKES AROUND MID-WEEK AND MAKE
LAKE EFFECT SHOWERS. AN ARCTIC AIR MASS BEGINS TO MOVE THROUGH
SOUTHERN CANADA AND DECREASING 850MB TEMPERATURES WILL CONTINUE
THROUGH THE LATTER HALF OF THE WEEK. CURRENT RUNS HAVE PA UNDER
M16C TEMPERATURES AT 850MB THURSDAY MORNING. THE GFS AND EC
PROPAGATE ANOTHER TROUGH THROUGH PENNSYLVANIA FRIDAY. THE EC
SPEEDS UP THIS TROUGH AS THE GFS SLOWS THE SYSTEM DOWN. THE
MOVEMENT OF THE LARGE UPPER LEVEL LOW DRIVING THIS SUCCESSIVE
SHORT WAVE TROUGHS VARIES BETWEEN THE MODELS. THE EC MOVES IT
QUICKER THROUGH NOVA SCOTIA AND THEN EXITING TO THE NORTHEAST. THE
GFS SLOWS IT DOWN ON A MORE EASTERLY TRACK. EITHER WAY...EXPECT
HIGH TEMPERATURES THIS WEEK TO BE AT OR BELOW FREEZING...MONDAY
AND TUESDAY BEING THE WARMEST DAYS. HIGHS AFTER THE TROUGH PASSAGE
INTO TUESDAY WILL HAVE HIGHS IN THE UPPER TEENS BY THE END OF THE
UP COMING WEEK. COUPLE THE LOW TEMPS WITH THE GUSTY FLOW...AND
WIND CHILLS COULD BE AN ISSUE DURING THIS TIME FRAME. LOWS THROUGH
THE LATER HALF OF THE WEEK SHOULD BE IN THE LOW TEENS.
&&
.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
NW UPSLOPE FLOW WILL KEEP IFR/MVFR CIGS AND SCT SNOW SHOWERS ACROSS
THE NW MTNS AND LAUREL HIGHLANDS THROUGH MUCH OF THE DAY. VFR TO
OCCASIONALLY MVFR IN -SNSH ACROSS THE CENTRAL MTN TERMINALS /AOO
AND UNV/. FARTHER EAST...CONDS HAVE RETURNED TO VFR...WITH EVEN
SOME BREAKS IN THE OVC.
WINDS ARE A PROBLEM ACROSS THE REGION...WITH BLUSTERY NW WINDS
OCCASIONALLY GUSTING OVER 30 MPH.
-SHSN ACTIVITY SHOULD TAPER OFF OVER NIGHT...ALTHOUGH CLOUDS MAY
LINGER ACROSS THE WEST.
OUTLOOK...
MON...VFR EAST...BECOMING VFR WEST.
MON NIGHT-TUES...SOME MVFR POSS...WITH LIGHT SNOW DEVELOPING.
WED-THU...GENERALLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR
PAZ024-033.
WIND ADVISORY UNTIL 3 PM EST THIS AFTERNOON FOR PAZ024>026-
033>036-056-057-059-063>066.
&&
$$
SYNOPSIS...DANGELO
NEAR TERM...GRUMM/DANGELO
SHORT TERM...GRUMM/DANGELO
LONG TERM...DANGELO/CERU
AVIATION...EVANEGO
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
959 AM EST SUN DEC 30 2012
.SYNOPSIS...
NORTHWEST FLOW WILL DOMINATE THE WEATHER PATTERN FOR THE NEXT
WEEK. THIS WILL CREATE A PROLONGED PERIOD OF COLDER THAN NORMAL
TEMPERATURES...BUT ALSO KEEP SIGNIFICANT STORMINESS CONFINED TO
SOUTH OF THE REGION.
&&
.NEAR TERM /UNTIL 7 PM THIS EVENING/...
SNOW SHOWERS CONTINUE OVER CENTRAL PENNSYLVANIA. EAST OF THE
HIGHER TERRAIN THEY MAINLY PRODUCE A BRIEF DUSTING OF SNOW. THERE
HAS BEEN A PERSISTENT NW TO SE BAND THAT HAS EXTENDED THROUGH
STATE COLLEGE AT TIMES...BUT RECENTLY THE HIGHER ECHOES HAVE
DRIFTED NORTH. THIS FEATURE HAS PRODUCED LIGHT SNOW SHOWERS.
THERE IS STILL SOME ON GOING SNOW IN THE SW MOUNTAINS AND WILL LET
THE ADVISORY FOR 3-5 INCHES OF SNOW EXPIRE AT 18Z AS SNOW
DIMINISHES DURING THE DAY AND ACCUMULATIONS DIMINISH TOO.
STRONG WINDS AT 850 HPA...OVER 50 KTS AND A FAIRLY GOOD PRESSURE
RISE-FALL COUPLET IN 6 HOUR NAM12 AND RUC13 HAVE FAVORED A WIND
ADVISORY. IN WESTERN PA WINDS OVER 40 KTS SHOULD BE CONFINED TO
ABOUT ABOVE ABOUT 1800 FT. SOME STRONGER WINDS WITH DOWN-SLOPE
EFFECT IN SOUTHERN PA POSSIBLE TOO. GUST ALREADY IN MID-30KT RANGE
IN LOWER SUSQUEHANNA VALLEY. PUT ADVISORY ACROSS ALL OF SOUTHERN
TIER TO INCLUDE YORK-HARRISBURG AND LANCASTER AREAS. SHOULD BE
OVER LATE AFTERNOON WITH INCREASING STABILITY.
&&
.SHORT TERM /7 PM THIS EVENING THROUGH TUESDAY/...
SNOW SUBSIDES IN WEST AND WINDS SLOWLY ABATE SUNDAY NIGHT. THERE
ARE HINTS OF SOME LIGHT SNOW MOVING INTO THE WESTERN AREAS LATE IN
THE AFTERNOON OR EVENING NEW YEARS EVE. AS STATE IN PREVIOUS
SHIFTS DISCUSSION...
PREVIOUS DISCUSSION....WARM ADVECTION TONIGHT WILL TRY TO CLEAR OUT THE
SKIES...BUT MESO MDLS STILL PRODUCE MEAGER QPF IN THE FAR NW.
THUS...SCT/ISOLD SHSN MAY CONTINUE FOR THE FIRST HALF OF THE
NIGHT. CLOUDS WILL BE TOUGH TO CLEAR OVER THE NRN HALF OF THE
AREA...AND HIGH CLOUDS WILL START TO ARRIVE FROM THE WEST BY
MONDAY MORNING. JET STREAM BRIEFLY RIDGES N OF THE AREA TONIGHT
AND MONDAY...BUT AN INCREASE IN SPEED WILL OCCUR MONDAY OVER THE
OHIO VALLEY AND SPREAD ACROSS THE STATE MON NIGHT. THIS WILL
TRANSPORT A LITTLE MOISTURE UP OVER THE SFC/UPPER RIDGE...BUT NOT
MUCH AT ALL. WESTERLY/UPSLOPE FLOW WILL HELP ADD LOW-LEVEL LIFT.
THE QPF GENERATED BY ALL THE MODELS AND IN THE SREF PLUMES IS LESS
THAN A TENTH - EVEN IN THOSE UPSLOPE AREAS. SO...WHILE VERY LIGHT
SNOW IS LIKELY IN THE WEST NEW YEARS EVE/NIGHT DUE TO THE
PERSISTENT CONSENSUS AMONG THE MDLS...THE ACCUMS WILL BE ALMOST
NIL. DRYING ON THE NWRLY WINDS AND BEHIND THE STRENGTHENING JET
STREAK WILL DECREASE THE POPS ON TUES...BUT -14C AIR CROSSING THE
LAKES WILL GENERATE SOME LAKE EFFECT SHSN DOWNWIND.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
LATEST MED RANGE GUID BACKS OFF ON THE MAGNITUDE/COLDNESS OF THE
AIR MASS MOVING INTO THE NERN U.S. THIS WEEK. THUS...HAVE BUMPED
UP THE TEMPS SLIGHTLY FOR THE LONG TERM. BUT THE NW FLOW
CONTINUES...AND NOTHING ELSE WAS CHANGED WITH THE OVERNIGHT PKG.
PREV DISC FOLLOWS...
LAKE ENHANCED BANDS SHOULD CONTINUE THROUGH WEDNESDAY
MORNING...AND PERHAPS WEDNESDAY AFTERNOON. A FEW NORTHERN STREAM
FEATURES WILL CROSS THE LOWER GREAT LAKES AROUND MID-WEEK AND MAKE
LAKE EFFECT SHOWERS. AN ARCTIC AIR MASS BEGINS TO MOVE THROUGH
SOUTHERN CANADA AND DECREASING 850MB TEMPERATURES WILL CONTINUE
THROUGH THE LATTER HALF OF THE WEEK. CURRENT RUNS HAVE PA UNDER
M16C TEMPERATURES AT 850MB THURSDAY MORNING. THE GFS AND EC
PROPAGATE ANOTHER TROUGH THROUGH PENNSYLVANIA FRIDAY. THE EC
SPEEDS UP THIS TROUGH AS THE GFS SLOWS THE SYSTEM DOWN. THE
MOVEMENT OF THE LARGE UPPER LEVEL LOW DRIVING THIS SUCCESSIVE
SHORT WAVE TROUGHS VARIES BETWEEN THE MODELS. THE EC MOVES IT
QUICKER THROUGH NOVA SCOTIA AND THEN EXITING TO THE NORTHEAST. THE
GFS SLOWS IT DOWN ON A MORE EASTERLY TRACK. EITHER WAY...EXPECT
HIGH TEMPERATURES THIS WEEK TO BE AT OR BELOW FREEZING...MONDAY
AND TUESDAY BEING THE WARMEST DAYS. HIGHS AFTER THE TROUGH PASSAGE
INTO TUESDAY WILL HAVE HIGHS IN THE UPPER TEENS BY THE END OF THE
UP COMING WEEK. COUPLE THE LOW TEMPS WITH THE GUSTY FLOW...AND
WIND CHILLS COULD BE AN ISSUE DURING THIS TIME FRAME. LOWS THROUGH
THE LATER HALF OF THE WEEK SHOULD BE IN THE LOW TEENS.
&&
.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
NW UPSLOPE FLOW WILL KEEP IFR/MVFR CIGS AND SCT SNOW SHOWERS ACROSS
THE NW MTNS AND LAUREL HIGHLANDS FOR A FEW HOURS PAST SUNRISE.
ELSEWHERE..CONDS HAVE RETURNED TO VFR...WITH EVEN SOME BREAKS IN THE
OVC OVER THE SE. MOST SIG BAND OF SNOW SHOWERS STRETCHES SE FROM
KAOO TO KTHV. THIS SHOULD MAKE FOR SOME REDUCED CIGS AND VSYBS BUT
REMAIN CLEAR OF ANY CENTRAL PA AIRFIELDS.
SNOW SHOULD DIMINISH AS DAY WEARS ON.
WINDS ARE PROBLEM ACROSS THE REGION WITH STRONG GUSTY NW WINDS AND
SIGNIFICANT GUST SPREADS AT TIMES THROUGH 20-21Z.
OUTLOOK...
FRI...MVFR/IFR OVER MOUNTAINS OF THE WEST WITH SNOW
SHOWERS...MVFR/VFR CENTRAL AND EASTERN TERMINALS WITH OCCASIONAL
SNOW SHOWERS/FLURRIES.
FRI NIGHT...IFR/LIFR OVER WESTERN MOUNTAINS IN SNOW SQUALLS...MVFR
TO VFR ELSEWHERE.
SAT...BREEZY. LAKE EFFECT SNOWS CONTINUE IN N AND WEST MTNS WITH
IFR/MVFR CONDITIONS. MVFR IN SNOW SHOWERS CENTRAL. VFR SE.
SUN...MVFR NW. VFR ELSEWHERE.
MON...GENERALLY VFR.
TUES...SOME MVFR POSS...WITH LIGHT RAIN/SNOW DEVELOPING.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR
PAZ024-033.
WIND ADVISORY UNTIL 3 PM EST THIS AFTERNOON FOR PAZ024>026-
033>036-056-057-059-063>066.
&&
$$
SYNOPSIS...DANGELO
NEAR TERM...GRUMM/DANGELO
SHORT TERM...GRUMM/DANGELO
LONG TERM...DANGELO/CERU
AVIATION...GRUMM/GARTNER
AREA FORECAST DISCUSSION
NWS TUCSON AZ
210 PM MST SUN DEC 30 2012
.SYNOPSIS...THERE IS A GOOD CHANCE OF VALLEY RAIN AND MOUNTAIN SNOW
THIS EVENING INTO MONDAY WITH SNOW ACCUMULATIONS AS LOW AS 3500
FEET. DRY CONDITIONS WILL THEN PREVAIL NEW YEARS DAY THROUGH
SATURDAY WITH A GRADUAL WARMING TREND.
&&
.DISCUSSION...UPPER TROUGH CONTINUES TO DEEPEN OVER THE SWRN CONUS
THIS AFTERNOON. UPPER LOW IS PROGGED TO MOVE EWD ACROSS NRN ARIZONA
TONIGHT...THEN SYSTEM WILL FILL AND MOVE RAPIDLY EWD INTO THE
CENTRAL CONUS PLAINS BY MON EVENING. 30/12Z UNIV OF ARIZONA WRF-NAM
AND WRF-GFS AS WELL AS THE 30/15Z RUC HRRR WERE VERY SIMILAR WITH
DEPICTING TWO PERIODS OF PRECIP ACROSS SE AZ TONIGHT. THE FIRST
PERIOD OF PRECIP IS FORECAST TO OCCUR BASICALLY FROM 6-10 PM MST OR
SO. MORE SHOWERS ARE PROGGED TO MOVE INTO WRN/CENTRAL PIMA COUNTY
AROUND MIDNIGHT...THEN WIDESPREAD VALLEY RAIN/MOUNTAIN SNOW TO OCCUR
LATE TONIGHT INTO MID-MORNING MON.
BASED ON THESE SOLUTIONS AS WELL AS THE 30/12Z NAM/GFS/ECMWF...HAVE
MAINTAINED THE INHERITED WINTER WEATHER ADVISORY FOR AZZ503-506>509
FROM MIDNIGHT TONIGHT TO 9 AM MST MONDAY ABOVE 3500 FEET. STILL
APPEARS THAT SNOW LEVELS LATE TONIGHT INTO MON MORNING WILL RANGE
FROM 3500-4000 FEET. PRECIP MON AFTERNOON TO BE CONFINED MOSTLY TO
GREENLEE...GRAHAM...AND COCHISE COUNTIES EAST OF TUCSON. DRY
CONDITIONS TO OCCUR MON NIGHT EXCEPT FOR A SLIGHT CHANCE OF SNOW
SHOWERS ACROSS THE WHITE MOUNTAINS.
STORM TOTAL LIQUID AMOUNTS ARE EXPECTED TO RANGE FROM ABOUT ONE
TENTH OF AN INCH TO NEARLY ONE THIRD OF AN INCH. STORM TOTAL SNOW
ACCUMULATIONS ABOVE 5000 FEET ARE FORECAST TO RANGE FROM 2-5
INCHES...OR JUST BELOW SNOW ADVISORY CRITERIA. HOWEVER...SNOW
ACCUMULATIONS OF 1 TO 2 INCHES BETWEEN 3500-5000 FEET JUSTIFY THE
WINTER WEATHER ADVISORY FOR THE LOWER ELEVATIONS OF GRAHAM/SRN
GREENLEE/COCHISE/ERN SANTA CRUZ/ERN PINAL COUNTIES.
DRIER NWLY/WLY FLOW ALOFT TUE...THEN GFS/ECMWF WERE SIMILAR WITH
MOVING THE NEXT UPPER LOW SEWD ACROSS NRN BAJA CALIFORNIA TUE NIGHT
AND EARLY WED. AT THIS TIME APPEARS THAT DRY CONDITIONS WILL OCCUR
TUE NIGHT-WED AS BULK OF MOISTURE WILL BE ABOVE 500 MB. UPPER RIDGE
TO THEN PREVAIL OVER THE WRN CONUS THUR-SAT. REMAINING DRY NEXT SUN
AS THE NEXT UPPER LOW IS PROGGED TO BE WELL WEST OF THE AREA.
MARKEDLY COLDER MON WITH HIGH TEMPS TO BE NEARLY 15 DEGS F OR SO
BELOW NORMAL. ALTHOUGH FAIRLY WIDESPREAD FREEZING TEMPS ARE FORECAST
TO OCCUR MON NIGHT...A HARD FREEZE APPEARS TO BE UNLIKELY. A VERY
GRADUAL WARMING TREND IS ON TAP TUE-SAT ALTHOUGH DAYTIME TEMPS ARE
EXPECTED TO REMAIN BELOW NORMAL.
&&
.AVIATION...CLOUD LOWERING TO GENERALLY 4-7K FT AGL THIS EVENING AND
CONTINUING THRU MONDAY MORNING. WIDESPREAD -SHRA AND HIGHER TERRAIN
-SHSN THIS EVENING THRU MONDAY MORNING. AREAS OF MVFR CIGS TONIGHT
WITH HIGHER TERRAIN OBSCURATIONS. SCT -SHRA/MTN -SHSN MAINLY EAST OF
KTUS MONDAY AFTERNOON. CLOUDS DECREASING WEST OF KTUS MONDAY
AFTERNOON WITH BKN-OVC CLOUDS MOSTLY AROUND 4-7K FT AGL EAST OF
KTUS. AREAS OF S-SW SURFACE WIND THIS EVENING 10-20 KTS WITH GUSTS
TO 30 KTS EAST AND SOUTH OF KTUS. SURFACE WIND AFTER 31/06Z EASING
TO LESS THAN 10 KTS THRU MONDAY AFTERNOON. AVIATION DISCUSSION NOT
UPDATED FOR TAF AMENDMENTS.
&&
.FIRE WEATHER...RAIN AND MOUNTAIN SNOW SHOWERS WILL MOVE ACROSS THE
AREA THIS EVENING THROUGH EARLY MONDAY WITH A FEW SCATTERED SHOWERS
MONDAY AFTERNOON. THE SOUTH TO SOUTHWEST BREEZE ACROSS PORTIONS OF
THE AREA WILL EASE OVERNIGHT. THEN DRY CONDITIONS WILL PREVAIL FROM
TUESDAY THROUGH NEXT WEEKEND WITH A VERY GRADUAL WARMING TREND.
WINDS WILL BE LIGHT THROUGH THE PERIOD AND PREDOMINATELY FROM AN
EASTERLY DIRECTION.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 9 AM MST MONDAY
FOR AZZ503-506>509 BETWEEN 3500 AND 5000 FEET.
&&
$$
VISIT US ON FACEBOOK...TWITTER...YOUTUBE...AND AT WEATHER.GOV/TUCSON
DISCUSSION...BF
AVIATION/FIRE WEATHER...CERNIGLIA
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
328 PM EST SUN DEC 30 2012
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW
&&
.SYNOPSIS...
ISSUED AT 242 PM EST SUN DEC 30 2012
A COLD FRONT AND UPPER TROUGH WILL MOVE INTO THE AREA ON MONDAY
BEFORE EXITING ON TUESDAY. THIS WILL BRING ANOTHER ROUND OF LIGHT
SNOW TO CENTRAL INDIANA. FOR WEDNESDAY INTO NEXT WEEKEND...COLD
AND DRY WEATHER WILL BE THE RULE.
&&
.NEAR TERM /TONIGHT/...
ISSUED AT 242 PM EST SUN DEC 30 2012
TEMPERATURES WILL BE TRICKY TONIGHT. MAINLY SOME HIGH CLOUDS EARLY
THIS EVENING...WITH SOUTHWEST WINDS. TEMPERATURES MAY FALL FOR A
WHILE THIS EVENING BEFORE LEVELING OUT OR RISING OVERNIGHT AS WARM
ADVECTION KICKS IN.
QUESTION BECOMES HOW FAR WILL TEMPERATURES FALL BEFORE LEVELING
OFF. FEEL THAT WITH THE SOUTHWEST WINDS STAYING UP TEMPERATURES
WILL NOT PLUMMET. DID ALLOW READINGS TO REACH 20-25...WHICH IS
COOLER THAN THE MET BUT CLOSE TO THE MAV.
CLOUDS WILL INCREASE AS ISENTROPIC LIFT CONTINUES IN THE WARM
ADVECTION TONIGHT.
&&
.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
ISSUED AT 242 PM EST SUN DEC 30 2012
FOCUS IS ON PRECIPITATION EVENT MONDAY INTO TUESDAY. MODELS ARE
ACTUALLY NOT THAT FAR FROM EACH OTHER...SO USED A BLEND FOR THE
MOST PART.
FORCING WILL INCREASE DURING THE DAY ON MONDAY AS COLD FRONT
APPROACHES. FIRST ROUND WITH ISENTROPIC LIFT WILL MAINLY IMPACT
THE AREA AFTER 18Z. GRADUALLY INCREASED POPS DURING THE
MORNING...FINALLY REACHING LIKELY CATEGORY DURING THE AFTERNOON
ALL AREAS. SOUNDINGS SHOW THAT ENTIRE ATMOSPHERE SHOULD REMAIN
BELOW FREEZING...WITH TEMPERATURES NEAR THE SURFACE AROUND
FREEZING. THUS PRECIPITATION SHOULD REMAIN AS SNOW.
BEST FORCING MONDAY AFTERNOON LOOKS TO BE IN THE NORTHERN FORECAST
AREA...SO WENT WITH AROUND AN INCH THERE. WENT LESS THAN AN INCH
SOUTH.
ANOTHER ROUND OF FORCING MOVES THROUGH MONDAY NIGHT...MAINLY
IMPACTING THE SOUTHERN FORECAST AREA. THUS WENT LIKELY POPS ACROSS
THE SOUTH HALF AND CHANCE POPS ACROSS THE NORTH. LOOKS LIKE AN
INCH POSSIBLE SOUTH WITH LESSER AMOUNTS NORTH.
GIVEN THE ABOVE ENDED UP WITH A STORM TOTAL OF 1-2 INCHES ACROSS
THE ENTIRE FORECAST AREA. WILL HAVE TO KEEP AN EYE ON HOW THIS
DEVELOPS THOUGH AS MODELS ARE HINTING AND SOME AREAS OF
FRONTOGENETICAL FORCING AND DECENT LIFT IN THE SNOW GROWTH LAYER
BOTH IN THE AFTERNOON AND AGAIN IN THE EVENING. THIS COULD LEAD TO
BANDS OF HIGHER AMOUNTS...PERHAPS REACHING INTO ADVISORY CRITERIA.
WILL CONTINUE TO MONITOR. WILL ISSUE A SPS TO HIGHLIGHT THE UPCOMING
SNOW.
KEPT LOW POPS TUESDAY MORNING AS THE FRONT EXITS...BUT TUESDAY
AFTERNOON NOW LOOKS DRY. HIGH PRESSURE WILL MOVE IN AND PROVIDE
DRY AND COLD WEATHER FOR TUESDAY NIGHT AND WEDNESDAY.
FOR TEMPERATURES...TRENDED TOWARD THE COOLER OF THE GUIDANCE WITH
SNOW ON THE GROUND.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
ISSUED AT 242 PM EST SUN DEC 30 2012
RATHER UNEVENTFUL LONG TERM PORTION WITH COLD HIGH PRESSURE
DOMINATING OUR WEATHER MOST OF THE PERIOD. MODELS INDICATE AN UPPER
TROUGH WILL BE MOVING BY AROUND THURSDAY NIGHT AND THERE MAY BE VERY
LOW CHANCES OF A FEW SNOW SHOWERS OR FLURRIES NORTH. ANOTHER WEAK
SYSTEM WILL BE MOVING THROUGH LATE DAY 6 AND DAY 7. AGAIN WE ARE
TALKING NO MORE THAN A FEW FLURRIES IF ANYTHING. HPC...ALL BLEND
AND CONSALL POPS ARE DRY. SEE NO REASON AT THIS TIME FROM DEVIATING
FROM THOSE NUMBERS THAT FAR OUT. THUS WILL KEEP LONG TERM PERIOD
DRY FOR NOW.
WENT A FEW DEGREES COLDER SOME PERIODS AS THERE SHOULD BE SOME SNOW
COVER THROUGHOUT THE EXTENDED. OTHERWISE...ONLY MINOR CHANGES MADE
TO ALL BLEND TEMPERATURES.
&&
.AVIATION /DISCUSSION FOR THE 30/21Z IND TAF UPDATE/...
ISSUED AT 328 PM EST SUN DEC 30 2012
ONLY MADE MINOR TWEAK TO INCREASE CIRRUS.
PREVIOUS DISCUSSION FOLLOWS...
VFR THROUGH THE NEXT 24 HOURS...THEN MVFR OR IFR SNOW POSSIBLE LATE
MONDAY AFTERNOON.
HIGH PRESSURE WILL MOVE EAST ACROSS THE OHIO VALLEY THIS AFTERNOON.
MODEL SOUNDINGS INDICATE MAINLY INCREASING HIGH CLOUDS BY THIS
EVENING FOLLOWED BY MID CLOUDS LATE TONIGHT AND MONDAY MORNING.
EARLIER SOME MODELS INDICATED COULD BE A FEW POCKETS OF STRATUS
DEVELOPING DUE TO SNOW MELT. SO FAR NO SITES HAVE THIS HAPPENING
AND RUC MODEL HAS TRENDED DRIER IN LOWER LAYERS...SO WILL DROP
MENTION OF SCT015 WHICH WAS IN PREVIOUS TAF.
A COLD FRONT WILL MOVE INTO NORTHERN INDIANA BY MIDDAY MONDAY AND
BOTH GFS AND NAM MODEL INDICATE LIGHT SNOW POSSIBLE BY LATE MONDAY.
THUS WILL ADD A GROUP IN KIND 30 HOUR TAF TO ACCOMMODATE THIS. THIS
IS BEYOND THE TIME OF OTHER CENTRAL INDIANA TAFS.
WINDS WILL BE SOUTHWEST AROUND 8 KNOTS OR LESS THIS AFTERNOON AND
TONIGHT AND SOUTHWEST UP TO 10 KNOTS ON MONDAY.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...50
NEAR TERM...50
SHORT TERM...50
LONG TERM....JH
AVIATION...JH/MK
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
242 PM EST SUN DEC 30 2012
.UPDATE...
THE SYNOPSIS...NEAR TERM...SHORT TERM AND LONG TERM SECTIONS HAVE
BEEN UPDATED BELOW
&&
.SYNOPSIS...
ISSUED AT 242 PM EST SUN DEC 30 2012
A COLD FRONT AND UPPER TROUGH WILL MOVE INTO THE AREA ON MONDAY
BEFORE EXITING ON TUESDAY. THIS WILL BRING ANOTHER ROUND OF LIGHT
SNOW TO CENTRAL INDIANA. FOR WEDNESDAY INTO NEXT WEEKEND...COLD
AND DRY WEATHER WILL BE THE RULE.
&&
.NEAR TERM /TONIGHT/...
ISSUED AT 242 PM EST SUN DEC 30 2012
TEMPERATURES WILL BE TRICKY TONIGHT. MAINLY SOME HIGH CLOUDS EARLY
THIS EVENING...WITH SOUTHWEST WINDS. TEMPERATURES MAY FALL FOR A
WHILE THIS EVENING BEFORE LEVELING OUT OR RISING OVERNIGHT AS WARM
ADVECTION KICKS IN.
QUESTION BECOMES HOW FAR WILL TEMPERATURES FALL BEFORE LEVELING
OFF. FEEL THAT WITH THE SOUTHWEST WINDS STAYING UP TEMPERATURES
WILL NOT PLUMMET. DID ALLOW READINGS TO REACH 20-25...WHICH IS
COOLER THAN THE MET BUT CLOSE TO THE MAV.
CLOUDS WILL INCREASE AS ISENTROPIC LIFT CONTINUES IN THE WARM
ADVECTION TONIGHT.
&&
.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
ISSUED AT 242 PM EST SUN DEC 30 2012
FOCUS IS ON PRECIPITATION EVENT MONDAY INTO TUESDAY. MODELS ARE
ACTUALLY NOT THAT FAR FROM EACH OTHER...SO USED A BLEND FOR THE
MOST PART.
FORCING WILL INCREASE DURING THE DAY ON MONDAY AS COLD FRONT
APPROACHES. FIRST ROUND WITH ISENTROPIC LIFT WILL MAINLY IMPACT
THE AREA AFTER 18Z. GRADUALLY INCREASED POPS DURING THE
MORNING...FINALLY REACHING LIKELY CATEGORY DURING THE AFTERNOON
ALL AREAS. SOUNDINGS SHOW THAT ENTIRE ATMOSPHERE SHOULD REMAIN
BELOW FREEZING...WITH TEMPERATURES NEAR THE SURFACE AROUND
FREEZING. THUS PRECIPITATION SHOULD REMAIN AS SNOW.
BEST FORCING MONDAY AFTERNOON LOOKS TO BE IN THE NORTHERN FORECAST
AREA...SO WENT WITH AROUND AN INCH THERE. WENT LESS THAN AN INCH
SOUTH.
ANOTHER ROUND OF FORCING MOVES THROUGH MONDAY NIGHT...MAINLY
IMPACTING THE SOUTHERN FORECAST AREA. THUS WENT LIKELY POPS ACROSS
THE SOUTH HALF AND CHANCE POPS ACROSS THE NORTH. LOOKS LIKE AN
INCH POSSIBLE SOUTH WITH LESSER AMOUNTS NORTH.
GIVEN THE ABOVE ENDED UP WITH A STORM TOTAL OF 1-2 INCHES ACROSS
THE ENTIRE FORECAST AREA. WILL HAVE TO KEEP AN EYE ON HOW THIS
DEVELOPS THOUGH AS MODELS ARE HINTING AND SOME AREAS OF
FRONTOGENETICAL FORCING AND DECENT LIFT IN THE SNOW GROWTH LAYER
BOTH IN THE AFTERNOON AND AGAIN IN THE EVENING. THIS COULD LEAD TO
BANDS OF HIGHER AMOUNTS...PERHAPS REACHING INTO ADVISORY CRITERIA.
WILL CONTINUE TO MONITOR. WILL ISSUE A SPS TO HIGHLIGHT THE UPCOMING
SNOW.
KEPT LOW POPS TUESDAY MORNING AS THE FRONT EXITS...BUT TUESDAY
AFTERNOON NOW LOOKS DRY. HIGH PRESSURE WILL MOVE IN AND PROVIDE
DRY AND COLD WEATHER FOR TUESDAY NIGHT AND WEDNESDAY.
FOR TEMPERATURES...TRENDED TOWARD THE COOLER OF THE GUIDANCE WITH
SNOW ON THE GROUND.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
ISSUED AT 242 PM EST SUN DEC 30 2012
RATHER UNEVENTFUL LONG TERM PORTION WITH COLD HIGH PRESSURE
DOMINATING OUR WEATHER MOST OF THE PERIOD. MODELS INDICATE AN UPPER
TROUGH WILL BE MOVING BY AROUND THURSDAY NIGHT AND THERE MAY BE VERY
LOW CHANCES OF A FEW SNOW SHOWERS OR FLURRIES NORTH. ANOTHER WEAK
SYSTEM WILL BE MOVING THROUGH LATE DAY 6 AND DAY 7. AGAIN WE ARE
TALKING NO MORE THAN A FEW FLURRIES IF ANYTHING. HPC...ALL BLEND
AND CONSALL POPS ARE DRY. SEE NO REASON AT THIS TIME FROM DEVIATING
FROM THOSE NUMBERS THAT FAR OUT. THUS WILL KEEP LONG TERM PERIOD
DRY FOR NOW.
WENT A FEW DEGREES COLDER SOME PERIODS AS THERE SHOULD BE SOME SNOW
COVER THROUGHOUT THE EXTENDED. OTHERWISE...ONLY MINOR CHANGES MADE
TO ALL BLEND TEMPERATURES.
&&
.AVIATION /DISCUSSION FOR THE 30/18Z TAF ISSUANCE/...
ISSUED AT 1208 PM EST SUN DEC 30 2012
VFR THROUGH THE NEXT 24 HOURS...THEN MVFR OR IFR SNOW POSSIBLE LATE
MONDAY AFTERNOON.
HIGH PRESSURE WILL MOVE EAST ACROSS THE OHIO VALLEY THIS AFTERNOON.
MODEL SOUNDINGS INDICATE MAINLY INCREASING HIGH CLOUDS BY THIS
EVENING FOLLOWED BY MID CLOUDS LATE TONIGHT AND MONDAY MORNING.
EARLIER SOME MODELS INDICATED COULD BE A FEW POCKETS OF STRATUS
DEVELOPING DUE TO SNOW MELT. SO FAR NO SITES HAVE THIS HAPPENING
AND RUC MODEL HAS TRENDED DRIER IN LOWER LAYERS...SO WILL DROP
MENTION OF SCT015 WHICH WAS IN PREVIOUS TAF.
A COLD FRONT WILL MOVE INTO NORTHERN INDIANA BY MIDDAY MONDAY AND
BOTH GFS AND NAM MODEL INDICATE LIGHT SNOW POSSIBLE BY LATE MONDAY.
THUS WILL ADD A GROUP IN KIND 30 HOUR TAF TO ACCOMMODATE THIS. THIS
IS BEYOND THE TIME OF OTHER CENTRAL INDIANA TAFS.
WINDS WILL BE SOUTHWEST AROUND 8 KNOTS OR LESS THIS AFTERNOON AND
TONIGHT AND SOUTHWEST UP TO 10 KNOTS ON MONDAY.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...50
NEAR TERM...50
SHORT TERM...50
LONG TERM....JH
AVIATION...JH
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1208 PM EST SUN DEC 30 2012
.UPDATE...
AVIATION SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 319 AM EST SUN DEC 30 2012
HIGH PRESSURE WILL BUILD IN TODAY...BUT ANOTHER COLD FRONT WILL
BRING SNOW CHANCES BACK INTO THE FORECAST FOR MONDAY INTO TUESDAY.
COLD AND DRY WEATHER WILL END THE WORK WEEK.
&&
.NEAR TERM /REST OF TODAY/...
ISSUED AT 1007 AM EST SUN DEC 30 2012
ADJUSTED HOURLY GRIDS TO REFLECT CURRENT TRENDS. FREEZING FOG SHOULD
LIFT SOON ACROSS THE FAR SOUTHERN FORECAST AREA DUE TO THE SUN
BURNING IT OFF. THERE AND OTHER AREAS WHERE IT CLEARED OVERNIGHT
SHOULD SEE TEMPERATURES REBOUND RELATIVELY QUICKLY WITH THE SUN.
DID LOWER MAX TEMPERATURES A BIT IN THE SOUTH WHERE THEY STARTED OUT
VERY COLD. OTHERWISE LEFT HIGHS ALONE WITH THE SUNSHINE EXPECTED
TODAY.
&&
.SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/...
ISSUED AT 319 AM EST SUN DEC 30 2012
FORECAST FOCUS IS ON PRECIPITATION CHANCES MONDAY INTO TUESDAY.
CLOUDS WILL INCREASE TONIGHT AS ISENTROPIC LIFT BEGINS AHEAD OF
THE FRONT. WENT SLIGHTLY ABOVE MOS TO ACCOUNT FOR INCREASING
CLOUDINESS.
FRONT MOVES IN ON MONDAY AND MONDAY NIGHT WITH ASSOCIATED UPPER
TROUGH AND CHANCES FOR PRECIPITATION WILL INCREASE. TRENDS CONTINUE
TO DEPICT BEST MOISTURE AND FORCING ACROSS THE SOUTHERN FORECAST
AREA AND THIS IS WHERE THE HIGHEST POPS (LIKELY) EXIST.
PRECIPITATION TYPE DOES NOT LOOK TO BE AN ISSUE THIS FAR NORTH AND
IS EXPECTED TO FALL IN ONLY THE FORM OF SNOW.
AS WITH THE EVENT ON FRIDAY NIGHT...AM A LITTLE CONCERNED AT THE
STRONG FRONTOGENIC FORCING AT 500H WHICH COULD PUSH SNOWFALL AMOUNTS
HIGHER THAN THE 1 TO 2 INCHES THE MODELS ARE PREDICTING. BUMPED UP
SNOWFALL AMOUNTS ACROSS THE ENTIRE CWA...FOR 2 TO 4 ACROSS THE FAR
SOUTH...1-3 ACROSS THE CENTER AND 1 TO 2 FOR THE NORTHERN
COUNTIES. THE SOUTHERN COUNTIES (THOSE SOUTH OF THE I-70 CORRIDOR)
ARE COMING CLOSE TO ADVISORY CRITERIA. PER COORDINATION WITH
SURROUNDING OFFICES WILL HOLD OFF ON ISSUING ONE NOW AND ISSUE AN
SPS.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
ISSUED AT 241 AM EST SUN DEC 30 2012
RATHER UNEVENTFUL LONG TERM PORTION OF THE FORECAST WITH COLD
SURFACE HIGH PRESSURE IN CONTROL FOR MOST OF THE PERIOD. MODELS DO
INDICATE A WEAKENING UPPER LEVEL DISTURBANCE LATE IN THE WEEK THAT
MAY BE ABLE TO PRODUCE FLURRIES...BUT NO POINT IN MESSING WITH A
TRACE EVENT 5-6 DAYS OUT.
TEMPERATURES WILL REMAIN BELOW NORMAL THROUGHOUT...AS MUCH AS
10-12 DEGREES BELOW NORMAL AT TIMES. ALLBLEND HANDLED THIS WELL
WITH FEW TWEAKS REQUIRED.
&&
.AVIATION /DISCUSSION FOR THE 30/18Z TAF ISSUANCE/...
ISSUED AT 1208 PM EST SUN DEC 30 2012
VFR THROUGH THE NEXT 24 HOURS...THEN MVFR OR IFR SNOW POSSIBLE LATE
MONDAY AFTERNOON.
HIGH PRESSURE WILL MOVE EAST ACROSS THE OHIO VALLEY THIS AFTERNOON.
MODEL SOUNDINGS INDICATE MAINLY INCREASING HIGH CLOUDS BY THIS
EVENING FOLLOWED BY MID CLOUDS LATE TONIGHT AND MONDAY MORNING.
EARLIER SOME MODELS INDICATED COULD BE A FEW POCKETS OF STRATUS
DEVELOPING DUE TO SNOW MELT. SO FAR NO SITES HAVE THIS HAPPENING
AND RUC MODEL HAS TRENDED DRIER IN LOWER LAYERS...SO WILL DROP
MENTION OF SCT015 WHICH WAS IN PREVIOUS TAF.
A COLD FRONT WILL MOVE INTO NORTHERN INDIANA BY MIDDAY MONDAY AND
BOTH GFS AND NAM MODEL INDICATE LIGHT SNOW POSSIBLE BY LATE MONDAY.
THUS WILL ADD A GROUP IN KIND 30 HOUR TAF TO ACCOMMODATE THIS. THIS
IS BEYOND THE TIME OF OTHER CENTRAL INDIANA TAFS.
WINDS WILL BE SOUTHWEST AROUND 8 KNOTS OR LESS THIS AFTERNOON AND
TONIGHT AND SOUTHWEST UP TO 10 KNOTS ON MONDAY.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...SMF
NEAR TERM...50
SHORT TERM...SMF
LONG TERM....NIELD
AVIATION...JH
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
316 PM EST SUN DEC 30 2012
.SYNOPSIS...
A TROUGH IS FORECAST TO PERSIST OVER THE EASTERN UNITED STATES FOR
THE NEXT WEEK. THIS WILL KEEP THE MAIN STORM TRACK SUPPRESSED TO
OUR SOUTH. A SURGE OF ARCTIC AIR AND A WEAK WAVE COULD BRING SNOW
SHOWERS TO WESTERN AREAS NEW YEARS EVE. BEHIND THIS SYSTEM THE
ARCTIC FRONT COULD PUSH INTO PENNSYLVANIA ON NEW YEARS DAY AND
INTO WEDNESDAY. GENERALLY COLD PATTERN WITH NO BIG STORMS FORECAST.
&&
.NEAR TERM /UNTIL 8 PM THIS EVENING/...
UPDATED GRIDS HAD TO PAINT IN THE BIG SNOW BAND THAT FORMED...SO
MUCH FOR THINGS DISSIPATING. BIG SNOW BAND WITH SOME STEADY SNOW
AND ACCUMULATING SNOW EXTENDS ACROSS PORTIONS OF
ELK...CLEARFIELD...CENTRE AND HUNTINGDON COUNTIES. MAY CLIP
NORTHERN BLAIR TOO. A FEW LOCATIONS COULD GET OVER AN INCH OF SNOW
FROM THIS. FOLLOWING THIS BETTER WITH SPECIAL WEATHER STATEMENTS.
AFFECTING PARTS OF I-80 AND I-99.
WE LET THE ADVISORY FOR THE SNOW IN THE SOUTHWEST EXPIRE. THOUGHT
THING WOULD WIND DOWN. BUT CLEARLY WE HAVE LINGERING STRONGER SNOW
SQUALL ISSUES THAN PREVIOUSLY THOUGHT OR INDICATED BY GUIDANCE.
EXTENDED SNOW PROBS WITH THIS BAND AND ANY OTHERS THROUGH 8 PM.
THERE IS ANOTHER NOTABLE BAND OVER LYCOMING AND CLINTON
COUNTIES...MUCH WEAKER BUT THAT COULD BE A FUNCTION OF REALITY AND
DISTANCE FROM THE RADAR. WE COULD BE OVERSHOOTING SOME OF IT. SO
AFTER 22-00Z EXPECT THINGS TO BE IMPROVING...S L O W L Y.
THE WINDS STILL STRONG BUT SHOULD BEGIN TO SLIDE BELOW POTENTIAL
TO REACH ADVISORY CATEGORY LEVELS. WE HAD TWO LOCATIONS REACH
MINIMAL VALUES FOR WINDS OR WIND GUSTS EARLIER TODAY.
&&
.SHORT TERM /8 PM THIS EVENING THROUGH TUESDAY/...
GUIDANCE SHOWS SNOW SHOWER ACTIVITY REALLY DROPPING OFF FAST. THE
NORTHWEST WINDS SLOWLY BECOME MORE WNW OVERNIGHT. THIS CAUSES THE
13KM RAP TO PRODUCE MORE ALONG LAKE ERIE BANDS WHICH SHOULD REDUCE
SNOW SHOWERS IN SOUTHWESTERN MOUNTAINS AND GRADUALLY OVER WARREN
AND MCKEAN COUNTY. MOST SNOW SHOULD CEASE. THERE IS A SIMILAR
TREND IN THE 4KM NAM IMPLIED SNOW-BANDS. THERE IS VIRTUALLY NOW
ACCUMULATING QPF IN PA IN THESE MODELS MUCH AFTER 21Z...SO THIS
PERIOD SHOULD BE RELATIVELY DRY TO START.
WINDS CONTINUE TO DIMINISH OVERNIGHT. A SLOW PROCESS AND THE
CLOUDS ARE SLOW TO DISSIPATE.
ON NEW YEARS DAY A NORTHERN STREAM WAVE AND ITS COLD FRONT WILL
ALLOW A SURGE OF WEAK WARM ADVECTION OVER THE RIDGE AND AHEAD OF
THE FRONT. THE MODELS AND ENSEMBLES IMPLY A POTENTIAL SURGE OF
LIGHT SNOW AHEAD OF THE SYSTEM LATE NEW YEARS EVE INTO EARLY NEW
YEARS. SNOW WOULD BE VERY LIGHT AND AT THIS TIME CONFINED TO
WESTERN AREAS. SHOWED SOME POPS LATER AFTERNOON AND EVENING AS
SNOW IN WESTERNMOST AREAS. THIS LOOKS VERY WEAK AND VERY LIGHT.
THE COLD AIR BEHIND THIS SYSTEM PUSHES SOME -20 TO -24C AIR INTO
THE NORTHEASTERN US..ARCTIC AIR...WITH THE -12 TO -15C CONTOURS
GETTING INTO PA DURING THE AFTERNOON TUESDAY. SOME VERY COLD AIR
WILL CLIP OUR AREA FOR A CHILLING START TO THE NEW YEAR.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
LATEST MED RANGE GUIDANCE CONTINUES TO BACK OFF ON THE
MAGNITUDE/COLDNESS OF THE AIR MASS MOVING INTO THE NERN U.S. THIS
WEEK. THUS...HAVE BUMPED UP THE TEMPS SLIGHTLY FOR THE LONG TERM.
BUT THE NW FLOW CONTINUES...AND NOTHING ELSE WAS CHANGED WITH THE
OVERNIGHT PKG. PREV DISC FOLLOWS...
LAKE ENHANCED BANDS SHOULD CONTINUE THROUGH WEDNESDAY
MORNING...AND PERHAPS WEDNESDAY AFTERNOON. A FEW NORTHERN STREAM
FEATURES WILL CROSS THE LOWER GREAT LAKES AROUND MID-WEEK AND MAKE
LAKE EFFECT SHOWERS. AN ARCTIC AIR MASS BEGINS TO MOVE THROUGH
SOUTHERN CANADA AND DECREASING 850MB TEMPERATURES WILL CONTINUE
THROUGH THE LATTER HALF OF THE WEEK. CURRENT RUNS HAVE PA UNDER
M16C TEMPERATURES AT 850MB THURSDAY MORNING. THE GFS AND EC
PROPAGATE ANOTHER TROUGH THROUGH PENNSYLVANIA FRIDAY. THE EC
SPEEDS UP THIS TROUGH AS THE GFS SLOWS THE SYSTEM DOWN. THE
MOVEMENT OF THE LARGE UPPER LEVEL LOW DRIVING THIS SUCCESSIVE
SHORT WAVE TROUGHS VARIES BETWEEN THE MODELS. THE EC MOVES IT
QUICKER THROUGH NOVA SCOTIA AND THEN EXITING TO THE NORTHEAST. THE
GFS SLOWS IT DOWN ON A MORE EASTERLY TRACK. EITHER WAY...EXPECT
HIGH TEMPERATURES THIS WEEK TO BE AT OR BELOW FREEZING...MONDAY
AND TUESDAY BEING THE WARMEST DAYS. HIGHS AFTER THE TROUGH PASSAGE
INTO TUESDAY WILL HAVE HIGHS IN THE UPPER TEENS BY THE END OF THE
UP COMING WEEK. COUPLE THE LOW TEMPS WITH THE GUSTY FLOW...AND
WIND CHILLS COULD BE AN ISSUE DURING THIS TIME FRAME. LOWS THROUGH
THE LATER HALF OF THE WEEK SHOULD BE IN THE LOW TEENS.
&&
.AVIATION /20Z SUNDAY THROUGH FRIDAY/...
NWRLY UPSLOPE FLOW WILL KEEP IFR/MVFR CONDS AND SCTD SHSN ACROSS
THE NW MTNS AND LAUREL HIGHLANDS INTO THIS EVENING. VFR TO
OCCASIONALLY MVFR IN -SHSN AT THE CENTRAL MTN TERMINALS /AOO AND
UNV/. FARTHER EAST...CONDS HAVE RETURNED TO VFR...WITH EVEN SOME
BREAKS IN THE OVC.
BLUSTERY NW WINDS WILL GRADUALLY BEGIN TO DIMINISH THIS EVE.
HOWEVER...OCCASIONAL GUSTS OVER 30 MPH REMAIN POSSIBLE UNTIL
THEN.
LINGERING SHSN ACTIVITY SHOULD TAPER OFF OVERNIGHT...ALTHOUGH
SOME LOW CLOUDS MAY LINGER ACROSS THE WEST.
CONDS IMPROVE ON AREA-WIDE MONDAY...AS HIGH PRESSURE BRIEFLY
BUILDS INTO THE REGION.
OUTLOOK...
MON...VFR EAST...BECOMING VFR WEST.
MON NIGHT-TUES...SOME MVFR POSS...WITH -SHSN POSS.
WED-THU...GENERALLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...GRUMM/DANGELO
NEAR TERM...GRUMM
SHORT TERM...GRUMM
LONG TERM...DANGELO/CERU
AVIATION...EVANEGO
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
250 PM EST SUN DEC 30 2012
.SYNOPSIS...
A TROUGH IS FORECAST TO PERSIST OVER THE EASTERN UNITED STATES FOR
THE NEXT WEEK. THIS WILL KEEP THE MAIN STORM TRACK SUPPRESSED TO
OUR SOUTH. A SURGE OF ARCTIC AIR AND A WEAK WAVE COULD BRING SNOW
SHOWERS TO WESTERN AREAS NEW YEARS EVE. BEHIND THIS SYSTEM THE
ARCTIC FRONT COULD PUSH INTO PENNSYLVANIA ON NEW YEARS DAY AND
INTO WEDNESDAY. GENERALLY COLD PATTERN WITH NO BIG STORMS FORECAST.
&&
.NEAR TERM /UNTIL 8 PM THIS EVENING/...
UPDATED GRIDS HAD TO PAINT IN THE BIG SNOW BAND THAT FORMED...SO
MUCH FOR THINGS DISSIPATING. BIG SNOW BAND WITH SOME STEADY SNOW
AND ACCUMULATING SNOW EXTENDS ACROSS PORTIONS OF
ELK...CLEARFIELD...CENTRE AND HUNTINGDON COUNTIES. MAY CLIP
NORTHERN BLAIR TOO. A FEW LOCATIONS COULD GET OVER AN INCH OF SNOW
FROM THIS. FOLLOWING THIS BETTER WITH SPECIAL WEATHER STATEMENTS.
AFFECTING PARTS OF I-80 AND I-99.
WE LET THE ADVISORY FOR THE SNOW IN THE SOUTHWEST EXPIRE. THOUGHT
THING WOULD WIND DOWN. BUT CLEARLY WE HAVE LINGERING STRONGER SNOW
SQUALL ISSUES THAN PREVIOUSLY THOUGHT OR INDICATED BY GUIDANCE.
EXTENDED SNOW PROBS WITH THIS BAND AND ANY OTHERS THROUGH 8 PM.
THERE IS ANOTHER NOTABLE BAND OVER LYCOMING AND CLINTON
COUNTIES...MUCH WEAKER BUT THAT COULD BE A FUNCTION OF REALITY AND
DISTANCE FROM THE RADAR. WE COULD BE OVERSHOOTING SOME OF IT. SO
AFTER 22-00Z EXPECT THINGS TO BE IMPROVING...S L O W L Y.
THE WINDS STILL STRONG BUT SHOULD BEGIN TO SLIDE BELOW POTENTIAL
TO REACH ADVISORY CATEGORY LEVELS. WE HAD TWO LOCATIONS REACH
MINIMAL VALUES FOR WINDS OR WIND GUSTS EARLIER TODAY.
&&
.SHORT TERM /8 PM THIS EVENING THROUGH TUESDAY/...
GUIDANCE SHOWS SNOW SHOWER ACTIVITY REALLY DROPPING OFF FAST. THE
NORTHWEST WINDS SLOWLY BECOME MORE WNW OVERNIGHT. THIS CAUSES THE
13KM RAP TO PRODUCE MORE ALONG LAKE ERIE BANDS WHICH SHOULD REDUCE
SNOW SHOWERS IN SOUTHWESTERN MOUNTAINS AND GRADUALLY OVER WARREN
AND MCKEAN COUNTY. MOST SNOW SHOULD CEASE. THERE IS A SIMILAR
TREND IN THE 4KM NAM IMPLIED SNOW-BANDS. THERE IS VIRTUALLY NOW
ACCUMULATING QPF IN PA IN THESE MODELS MUCH AFTER 21Z...SO THIS
PERIOD SHOULD BE RELATIVELY DRY TO START.
WINDS CONTINUE TO DIMINISH OVERNIGHT. A SLOW PROCESS AND THE
CLOUDS ARE SLOW TO DISSIPATE.
ON NEW YEARS DAY A NORTHERN STREAM WAVE AND ITS COLD FRONT WILL
ALLOW A SURGE OF WEAK WARM ADVECTION OVER THE RIDGE AND AHEAD OF
THE FRONT. THE MODELS AND ENSEMBLES IMPLY A POTENTIAL SURGE OF
LIGHT SNOW AHEAD OF THE SYSTEM LATE NEW YEARS EVE INTO EARLY NEW
YEARS. SNOW WOULD BE VERY LIGHT AND AT THIS TIME CONFINED TO
WESTERN AREAS. SHOWED SOME POPS LATER AFTERNOON AND EVENING AS
SNOW IN WESTERNMOST AREAS. THIS LOOKS VERY WEAK AND VERY LIGHT.
THE COLD AIR BEHIND THIS SYSTEM PUSHES SOME -20 TO -24C AIR INTO
THE NORTHEASTERN US..ARCTIC AIR...WITH THE -12 TO -15C CONTOURS
GETTING INTO PA DURING THE AFTERNOON TUESDAY. SOME VERY COLD AIR
WILL CLIP OUR AREA FOR A CHILLING START TO THE NEW YEAR.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
LATEST MED RANGE GUID BACKS OFF ON THE MAGNITUDE/COLDNESS OF THE
AIR MASS MOVING INTO THE NERN U.S. THIS WEEK. THUS...HAVE BUMPED
UP THE TEMPS SLIGHTLY FOR THE LONG TERM. BUT THE NW FLOW
CONTINUES...AND NOTHING ELSE WAS CHANGED WITH THE OVERNIGHT PKG.
PREV DISC FOLLOWS...
LAKE ENHANCED BANDS SHOULD CONTINUE THROUGH WEDNESDAY
MORNING...AND PERHAPS WEDNESDAY AFTERNOON. A FEW NORTHERN STREAM
FEATURES WILL CROSS THE LOWER GREAT LAKES AROUND MID-WEEK AND MAKE
LAKE EFFECT SHOWERS. AN ARCTIC AIR MASS BEGINS TO MOVE THROUGH
SOUTHERN CANADA AND DECREASING 850MB TEMPERATURES WILL CONTINUE
THROUGH THE LATTER HALF OF THE WEEK. CURRENT RUNS HAVE PA UNDER
M16C TEMPERATURES AT 850MB THURSDAY MORNING. THE GFS AND EC
PROPAGATE ANOTHER TROUGH THROUGH PENNSYLVANIA FRIDAY. THE EC
SPEEDS UP THIS TROUGH AS THE GFS SLOWS THE SYSTEM DOWN. THE
MOVEMENT OF THE LARGE UPPER LEVEL LOW DRIVING THIS SUCCESSIVE
SHORT WAVE TROUGHS VARIES BETWEEN THE MODELS. THE EC MOVES IT
QUICKER THROUGH NOVA SCOTIA AND THEN EXITING TO THE NORTHEAST. THE
GFS SLOWS IT DOWN ON A MORE EASTERLY TRACK. EITHER WAY...EXPECT
HIGH TEMPERATURES THIS WEEK TO BE AT OR BELOW FREEZING...MONDAY
AND TUESDAY BEING THE WARMEST DAYS. HIGHS AFTER THE TROUGH PASSAGE
INTO TUESDAY WILL HAVE HIGHS IN THE UPPER TEENS BY THE END OF THE
UP COMING WEEK. COUPLE THE LOW TEMPS WITH THE GUSTY FLOW...AND
WIND CHILLS COULD BE AN ISSUE DURING THIS TIME FRAME. LOWS THROUGH
THE LATER HALF OF THE WEEK SHOULD BE IN THE LOW TEENS.
&&
.AVIATION /20Z SUNDAY THROUGH FRIDAY/...
NWRLY UPSLOPE FLOW WILL KEEP IFR/MVFR CONDS AND SCTD SHSN ACROSS
THE NW MTNS AND LAUREL HIGHLANDS INTO THIS EVENING. VFR TO
OCCASIONALLY MVFR IN -SHSN AT THE CENTRAL MTN TERMINALS /AOO AND
UNV/. FARTHER EAST...CONDS HAVE RETURNED TO VFR...WITH EVEN SOME
BREAKS IN THE OVC.
BLUSTERY NW WINDS WILL GRADUALLY BEGIN TO DIMINISH THIS EVE.
HOWEVER...OCCASIONAL GUSTS OVER 30 MPH REMAIN POSSIBLE UNTIL
THEN.
LINGERING SHSN ACTIVITY SHOULD TAPER OFF OVERNIGHT...ALTHOUGH
SOME LOW CLOUDS MAY LINGER ACROSS THE WEST.
CONDS IMPROVE ON AREA-WIDE MONDAY...AS HIGH PRESSURE BRIEFLY
BUILDS INTO THE REGION.
OUTLOOK...
MON...VFR EAST...BECOMING VFR WEST.
MON NIGHT-TUES...SOME MVFR POSS...WITH -SHSN POSS.
WED-THU...GENERALLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY UNTIL 3 PM EST THIS AFTERNOON FOR PAZ024>026-
033>036-056-057-059-063>066.
&&
$$
SYNOPSIS...GRUMM/DANGELO
NEAR TERM...GRUMM
SHORT TERM...GRUMM
LONG TERM...DANGELO/CERU
AVIATION...EVANEGO
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
108 PM EST SUN DEC 30 2012
.SYNOPSIS...
A TROUGH IS FORECAST TO PERSIST OVER THE EASTERN UNITED STATES FOR
THE NEXT WEEK. THIS WILL KEEP THE MAIN STORM TRACK SUPPRESSED TO
OUR SOUTH. A SURGE OF ARCTIC AIR AND A WEAK WAVE COULD BRING SNOW
SHOWERS TO WESTERN AREAS NEW YEARS EVE. BEHIND THIS SYSTEM THE
ARCTIC FRONT COULD PUSH INTO PENNSYLVANIA ON NEW YEARS DAY AND
INTO WEDNESDAY. GENERALLY COLD PATTERN WITH NO BIG STORMS FORECAST.
&&
.NEAR TERM /UNTIL 8 PM THIS EVENING/...
LETTING THE ADVISORY FOR THE SNOW IN THE SOUTHWEST GRACEFULLY
EXPIRE. SNOW SHOWERS CONTINUE OVER THE REGION THIS AFTERNOON. BUT
MODELS SUGGEST THE ORIENTATION OF THE BANDS WILL CHANGE AS THE
WINDS BEGIN TO BECOME MORE WESTERLY ALOFT. MODEL SOUNDINGS ALSO
SHOW A GENERAL TREND TO MORE STABLE CONDITIONS. AN INVERSION IS
NOW PRESENT AND SHOULD LOWER OVER THE NEXT 3-6 HOURS HELPING
DECREASE THE ACTIVITY. EXPECT MOST SNOW SHOWERS TO END AROUND 20Z
BUT LINGER LONGER IN THE SW MOUNTAINS AND WARREN COUNTY AREA.
MOST AREAS WILL SEE SOME LIGHT FLURRIES WITH LIMITED ACCUMULATING
SNOW. SOUTHEAST AREAS AT BEST MIGHT SEE A FLURRY OR TOO. BUT
CHANCES ARE DIMINISHING. CLOUDS WILL HANG TOUGH WITH BEST PEAKS OF
SUN OVER SOUTHEAST. YORK COUNTY CURRENTLY LOOKS BEST FOR SOME SUN
AT TIMES BUT MOST OF SOUTHEAST IS IMPROVING...S L O W L Y.
THE WINDS TOO SHOULD SLOW DIMINISH AND WILL LET THE ADVISORY
GRACEFULLY EXPIRE IN ABOUT 2 HOURS. WE HAD AT LEAST ONE REPORT OF
SUSTAINED WINDS OF OR OVER 27KTS (KMDT) EARLIER TODAY. WINDS
SHOULD BE ON THE DOWN TICK IN OVER THE NEXT 2-4 HOURS. STILL SOME
GUSTS EARLY TONIGHT BUT ALL SHOULD BE SUB-ADVISORY.
&&
.SHORT TERM /8 PM THIS EVENING THROUGH TUESDAY/...
GUIDANCE SHOWS SNOW SHOWER ACTIVITY REALLY DROPPING OFF FAST. THE
NORTHWEST WINDS SLOWLY BECOME MORE WNW OVERNIGHT. THIS CAUSES THE
13KM RAP TO PRODUCE MORE ALONG LAKE ERIE BANDS WHICH SHOULD REDUCE
SNOW SHOWERS IN SOUTHWESTERN MOUNTAINS AND GRADUALLY OVER WARREN
AND MCKEAN COUNTY. MOST SNOW SHOULD CEASE. THERE IS A SIMILAR
TREND IN THE 4KM NAM IMPLIED SNOW-BANDS. THERE IS VIRTUALLY NOW
ACCUMULATING QPF IN PA IN THESE MODELS MUCH AFTER 21Z...SO THIS
PERIOD SHOULD BE RELATIVELY DRY TO START.
WINDS CONTINUE TO DIMINISH OVERNIGHT. A SLOW PROCESS AND THE
CLOUDS ARE SLOW TO DISSIPATE.
ON NEW YEARS DAY A NORTHERN STREAM WAVE AND ITS COLD FRONT WILL
ALLOW A SURGE OF WEAK WARM ADVECTION OVER THE RIDGE AND AHEAD OF
THE FRONT. THE MODELS AND ENSEMBLES IMPLY A POTENTIAL SURGE OF
LIGHT SNOW AHEAD OF THE SYSTEM LATE NEW YEARS EVE INTO EARLY NEW
YEARS. SNOW WOULD BE VERY LIGHT AND AT THIS TIME CONFINED TO
WESTERN AREAS. SHOWED SOME POPS LATER AFTERNOON AND EVENING AS
SNOW IN WESTERNMOST AREAS. THIS LOOKS VERY WEAK AND VERY LIGHT.
THE COLD AIR BEHIND THIS SYSTEM PUSHES SOME -20 TO -24C AIR INTO
THE NORTHEASTERN US..ARCTIC AIR...WITH THE -12 TO -15C CONTOURS
GETTING INTO PA DURING THE AFTERNOON TUESDAY. SOME VERY COLD AIR
WILL CLIP OUR AREA FOR A CHILLING START TO THE NEW YEAR.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
LATEST MED RANGE GUID BACKS OFF ON THE MAGNITUDE/COLDNESS OF THE
AIR MASS MOVING INTO THE NERN U.S. THIS WEEK. THUS...HAVE BUMPED
UP THE TEMPS SLIGHTLY FOR THE LONG TERM. BUT THE NW FLOW
CONTINUES...AND NOTHING ELSE WAS CHANGED WITH THE OVERNIGHT PKG.
PREV DISC FOLLOWS...
LAKE ENHANCED BANDS SHOULD CONTINUE THROUGH WEDNESDAY
MORNING...AND PERHAPS WEDNESDAY AFTERNOON. A FEW NORTHERN STREAM
FEATURES WILL CROSS THE LOWER GREAT LAKES AROUND MID-WEEK AND MAKE
LAKE EFFECT SHOWERS. AN ARCTIC AIR MASS BEGINS TO MOVE THROUGH
SOUTHERN CANADA AND DECREASING 850MB TEMPERATURES WILL CONTINUE
THROUGH THE LATTER HALF OF THE WEEK. CURRENT RUNS HAVE PA UNDER
M16C TEMPERATURES AT 850MB THURSDAY MORNING. THE GFS AND EC
PROPAGATE ANOTHER TROUGH THROUGH PENNSYLVANIA FRIDAY. THE EC
SPEEDS UP THIS TROUGH AS THE GFS SLOWS THE SYSTEM DOWN. THE
MOVEMENT OF THE LARGE UPPER LEVEL LOW DRIVING THIS SUCCESSIVE
SHORT WAVE TROUGHS VARIES BETWEEN THE MODELS. THE EC MOVES IT
QUICKER THROUGH NOVA SCOTIA AND THEN EXITING TO THE NORTHEAST. THE
GFS SLOWS IT DOWN ON A MORE EASTERLY TRACK. EITHER WAY...EXPECT
HIGH TEMPERATURES THIS WEEK TO BE AT OR BELOW FREEZING...MONDAY
AND TUESDAY BEING THE WARMEST DAYS. HIGHS AFTER THE TROUGH PASSAGE
INTO TUESDAY WILL HAVE HIGHS IN THE UPPER TEENS BY THE END OF THE
UP COMING WEEK. COUPLE THE LOW TEMPS WITH THE GUSTY FLOW...AND
WIND CHILLS COULD BE AN ISSUE DURING THIS TIME FRAME. LOWS THROUGH
THE LATER HALF OF THE WEEK SHOULD BE IN THE LOW TEENS.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
NWRLY UPSLOPE FLOW WILL KEEP IFR/MVFR CONDS AND SCTD SHSN ACROSS
THE NW MTNS AND LAUREL HIGHLANDS INTO THIS EVENING. VFR TO
OCCASIONALLY MVFR IN -SHSN AT THE CENTRAL MTN TERMINALS /AOO AND
UNV/. FARTHER EAST...CONDS HAVE RETURNED TO VFR...WITH EVEN SOME
BREAKS IN THE OVC.
BLUSTERY NW WINDS WILL GRADUALLY BEGIN TO DIMINISH THIS EVE.
HOWEVER...OCCASIONAL GUSTS OVER 30 MPH REMAIN POSSIBLE UNTIL
THEN.
LINGERING SHSN ACTIVITY SHOULD TAPER OFF OVERNIGHT...ALTHOUGH
SOME LOW CLOUDS MAY LINGER ACROSS THE WEST.
CONDS IMPROVE ON AREA-WIDE MONDAY...AS HIGH PRESSURE BRIEFLY
BUILDS INTO THE REGION.
OUTLOOK...
MON...VFR EAST...BECOMING VFR WEST.
MON NIGHT-TUES...SOME MVFR POSS...WITH -SHSN POSS.
WED-THU...GENERALLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR
PAZ024-033.
WIND ADVISORY UNTIL 3 PM EST THIS AFTERNOON FOR PAZ024>026-
033>036-056-057-059-063>066.
&&
$$
SYNOPSIS...GRUMM/DANGELO
NEAR TERM...GRUMM
SHORT TERM...GRUMM
LONG TERM...DANGELO/CERU
AVIATION...EVANEGO
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1229 PM EST SUN DEC 30 2012
.SYNOPSIS...
A TROUGH IS FORECAST TO PERSIST OVER THE EASTERN UNITED STATES FOR
THE NEXT WEEK. THIS WILL KEEP THE MAIN STORM TRACK SUPPRESSED TO
OUR SOUTH. A SURGE OF ARCTIC AIR AND A WEAK WAVE COULD BRING SNOW
SHOWERS TO WESTERN AREAS NEW YEARS EVE. BEHIND THIS SYSTEM THE
ARCTIC FRONT COULD PUSH INTO PENNSYLVANIA ON NEW YEARS DAY AND
INTO WEDNESDAY. GENERALLY COLD PATTERN WITH NO BIG STORMS FORECAST.
&&
.NEAR TERM /UNTIL 7 PM THIS EVENING/...
SNOW SHOWERS CONTINUE OVER CENTRAL PENNSYLVANIA. EAST OF THE
HIGHER TERRAIN THEY MAINLY PRODUCE A BRIEF DUSTING OF SNOW. THERE
HAS BEEN A PERSISTENT NW TO SE BAND THAT HAS EXTENDED THROUGH
STATE COLLEGE AT TIMES...BUT RECENTLY THE HIGHER ECHOES HAVE
DRIFTED NORTH. THIS FEATURE HAS PRODUCED LIGHT SNOW SHOWERS.
THERE IS STILL SOME ON GOING SNOW IN THE SW MOUNTAINS AND WILL LET
THE ADVISORY FOR 3-5 INCHES OF SNOW EXPIRE AT 18Z AS SNOW
DIMINISHES DURING THE DAY AND ACCUMULATIONS DIMINISH TOO.
STRONG WINDS AT 850 HPA...OVER 50 KTS AND A FAIRLY GOOD PRESSURE
RISE-FALL COUPLET IN 6 HOUR NAM12 AND RUC13 HAVE FAVORED A WIND
ADVISORY. IN WESTERN PA WINDS OVER 40 KTS SHOULD BE CONFINED TO
ABOUT ABOVE ABOUT 1800 FT. SOME STRONGER WINDS WITH DOWN-SLOPE
EFFECT IN SOUTHERN PA POSSIBLE TOO. GUST ALREADY IN MID-30KT RANGE
IN LOWER SUSQUEHANNA VALLEY. PUT ADVISORY ACROSS ALL OF SOUTHERN
TIER TO INCLUDE YORK-HARRISBURG AND LANCASTER AREAS. SHOULD BE
OVER LATE AFTERNOON WITH INCREASING STABILITY.
&&
.SHORT TERM /7 PM THIS EVENING THROUGH TUESDAY/...
SNOW SUBSIDES IN WEST AND WINDS SLOWLY ABATE SUNDAY NIGHT. THERE
ARE HINTS OF SOME LIGHT SNOW MOVING INTO THE WESTERN AREAS LATE IN
THE AFTERNOON OR EVENING NEW YEARS EVE. AS STATE IN PREVIOUS
SHIFTS DISCUSSION...
PREVIOUS DISCUSSION....WARM ADVECTION TONIGHT WILL TRY TO CLEAR OUT THE
SKIES...BUT MESO MDLS STILL PRODUCE MEAGER QPF IN THE FAR NW.
THUS...SCT/ISOLD SHSN MAY CONTINUE FOR THE FIRST HALF OF THE
NIGHT. CLOUDS WILL BE TOUGH TO CLEAR OVER THE NRN HALF OF THE
AREA...AND HIGH CLOUDS WILL START TO ARRIVE FROM THE WEST BY
MONDAY MORNING. JET STREAM BRIEFLY RIDGES N OF THE AREA TONIGHT
AND MONDAY...BUT AN INCREASE IN SPEED WILL OCCUR MONDAY OVER THE
OHIO VALLEY AND SPREAD ACROSS THE STATE MON NIGHT. THIS WILL
TRANSPORT A LITTLE MOISTURE UP OVER THE SFC/UPPER RIDGE...BUT NOT
MUCH AT ALL. WESTERLY/UPSLOPE FLOW WILL HELP ADD LOW-LEVEL LIFT.
THE QPF GENERATED BY ALL THE MODELS AND IN THE SREF PLUMES IS LESS
THAN A TENTH - EVEN IN THOSE UPSLOPE AREAS. SO...WHILE VERY LIGHT
SNOW IS LIKELY IN THE WEST NEW YEARS EVE/NIGHT DUE TO THE
PERSISTENT CONSENSUS AMONG THE MDLS...THE ACCUMS WILL BE ALMOST
NIL. DRYING ON THE NWRLY WINDS AND BEHIND THE STRENGTHENING JET
STREAK WILL DECREASE THE POPS ON TUES...BUT -14C AIR CROSSING THE
LAKES WILL GENERATE SOME LAKE EFFECT SHSN DOWNWIND.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
LATEST MED RANGE GUID BACKS OFF ON THE MAGNITUDE/COLDNESS OF THE
AIR MASS MOVING INTO THE NERN U.S. THIS WEEK. THUS...HAVE BUMPED
UP THE TEMPS SLIGHTLY FOR THE LONG TERM. BUT THE NW FLOW
CONTINUES...AND NOTHING ELSE WAS CHANGED WITH THE OVERNIGHT PKG.
PREV DISC FOLLOWS...
LAKE ENHANCED BANDS SHOULD CONTINUE THROUGH WEDNESDAY
MORNING...AND PERHAPS WEDNESDAY AFTERNOON. A FEW NORTHERN STREAM
FEATURES WILL CROSS THE LOWER GREAT LAKES AROUND MID-WEEK AND MAKE
LAKE EFFECT SHOWERS. AN ARCTIC AIR MASS BEGINS TO MOVE THROUGH
SOUTHERN CANADA AND DECREASING 850MB TEMPERATURES WILL CONTINUE
THROUGH THE LATTER HALF OF THE WEEK. CURRENT RUNS HAVE PA UNDER
M16C TEMPERATURES AT 850MB THURSDAY MORNING. THE GFS AND EC
PROPAGATE ANOTHER TROUGH THROUGH PENNSYLVANIA FRIDAY. THE EC
SPEEDS UP THIS TROUGH AS THE GFS SLOWS THE SYSTEM DOWN. THE
MOVEMENT OF THE LARGE UPPER LEVEL LOW DRIVING THIS SUCCESSIVE
SHORT WAVE TROUGHS VARIES BETWEEN THE MODELS. THE EC MOVES IT
QUICKER THROUGH NOVA SCOTIA AND THEN EXITING TO THE NORTHEAST. THE
GFS SLOWS IT DOWN ON A MORE EASTERLY TRACK. EITHER WAY...EXPECT
HIGH TEMPERATURES THIS WEEK TO BE AT OR BELOW FREEZING...MONDAY
AND TUESDAY BEING THE WARMEST DAYS. HIGHS AFTER THE TROUGH PASSAGE
INTO TUESDAY WILL HAVE HIGHS IN THE UPPER TEENS BY THE END OF THE
UP COMING WEEK. COUPLE THE LOW TEMPS WITH THE GUSTY FLOW...AND
WIND CHILLS COULD BE AN ISSUE DURING THIS TIME FRAME. LOWS THROUGH
THE LATER HALF OF THE WEEK SHOULD BE IN THE LOW TEENS.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
NWRLY UPSLOPE FLOW WILL KEEP IFR/MVFR CONDS AND SCTD SHSN ACROSS
THE NW MTNS AND LAUREL HIGHLANDS INTO THIS EVENING. VFR TO
OCCASIONALLY MVFR IN -SHSN AT THE CENTRAL MTN TERMINALS /AOO AND
UNV/. FARTHER EAST...CONDS HAVE RETURNED TO VFR...WITH EVEN SOME
BREAKS IN THE OVC.
BLUSTERY NW WINDS WILL GRADUALLY BEGIN TO DIMINISH THIS EVE.
HOWEVER...OCCASIONAL GUSTS OVER 30 MPH REMAIN POSSIBLE UNTIL
THEN.
LINGERING SHSN ACTIVITY SHOULD TAPER OFF OVERNIGHT...ALTHOUGH
SOME LOW CLOUDS MAY LINGER ACROSS THE WEST.
CONDS IMPROVE ON AREA-WIDE MONDAY...AS HIGH PRESSURE BRIEFLY
BUILDS INTO THE REGION.
OUTLOOK...
MON...VFR EAST...BECOMING VFR WEST.
MON NIGHT-TUES...SOME MVFR POSS...WITH -SHSN POSS.
WED-THU...GENERALLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR
PAZ024-033.
WIND ADVISORY UNTIL 3 PM EST THIS AFTERNOON FOR PAZ024>026-
033>036-056-057-059-063>066.
&&
$$
SYNOPSIS...GRUMM/DANGELO
NEAR TERM...GRUMM/DANGELO
SHORT TERM...GRUMM/DANGELO
LONG TERM...DANGELO/CERU
AVIATION...EVANEGO
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1215 PM EST SUN DEC 30 2012
.SYNOPSIS...
A TROUGH IS FORECAST TO PERSIST OVER THE EASTERN UNITED STATES FOR
THE NEXT WEEK. THIS WILL KEEP THE MAIN STORM TRACK SUPPRESSED TO
OUR SOUTH. A SURGE OF ARCTIC AIR AND A WEAK WAVE COULD BRING SNOW
SHOWERS TO WESTERN AREAS NEW YEARS EVE. BEHIND THIS SYSTEM THE
ARCTIC FRONT COULD PUSH INTO PENNSYLVANIA ON NEW YEARS DAY AND
INTO WEDNESDAY. GENERALLY COLD PATTERN WITH NO BIG STORMS FORECAST.
&&
.NEAR TERM /UNTIL 7 PM THIS EVENING/...
SNOW SHOWERS CONTINUE OVER CENTRAL PENNSYLVANIA. EAST OF THE
HIGHER TERRAIN THEY MAINLY PRODUCE A BRIEF DUSTING OF SNOW. THERE
HAS BEEN A PERSISTENT NW TO SE BAND THAT HAS EXTENDED THROUGH
STATE COLLEGE AT TIMES...BUT RECENTLY THE HIGHER ECHOES HAVE
DRIFTED NORTH. THIS FEATURE HAS PRODUCED LIGHT SNOW SHOWERS.
THERE IS STILL SOME ON GOING SNOW IN THE SW MOUNTAINS AND WILL LET
THE ADVISORY FOR 3-5 INCHES OF SNOW EXPIRE AT 18Z AS SNOW
DIMINISHES DURING THE DAY AND ACCUMULATIONS DIMINISH TOO.
STRONG WINDS AT 850 HPA...OVER 50 KTS AND A FAIRLY GOOD PRESSURE
RISE-FALL COUPLET IN 6 HOUR NAM12 AND RUC13 HAVE FAVORED A WIND
ADVISORY. IN WESTERN PA WINDS OVER 40 KTS SHOULD BE CONFINED TO
ABOUT ABOVE ABOUT 1800 FT. SOME STRONGER WINDS WITH DOWN-SLOPE
EFFECT IN SOUTHERN PA POSSIBLE TOO. GUST ALREADY IN MID-30KT RANGE
IN LOWER SUSQUEHANNA VALLEY. PUT ADVISORY ACROSS ALL OF SOUTHERN
TIER TO INCLUDE YORK-HARRISBURG AND LANCASTER AREAS. SHOULD BE
OVER LATE AFTERNOON WITH INCREASING STABILITY.
&&
.SHORT TERM /7 PM THIS EVENING THROUGH TUESDAY/...
SNOW SUBSIDES IN WEST AND WINDS SLOWLY ABATE SUNDAY NIGHT. THERE
ARE HINTS OF SOME LIGHT SNOW MOVING INTO THE WESTERN AREAS LATE IN
THE AFTERNOON OR EVENING NEW YEARS EVE. AS STATE IN PREVIOUS
SHIFTS DISCUSSION...
PREVIOUS DISCUSSION....WARM ADVECTION TONIGHT WILL TRY TO CLEAR OUT THE
SKIES...BUT MESO MDLS STILL PRODUCE MEAGER QPF IN THE FAR NW.
THUS...SCT/ISOLD SHSN MAY CONTINUE FOR THE FIRST HALF OF THE
NIGHT. CLOUDS WILL BE TOUGH TO CLEAR OVER THE NRN HALF OF THE
AREA...AND HIGH CLOUDS WILL START TO ARRIVE FROM THE WEST BY
MONDAY MORNING. JET STREAM BRIEFLY RIDGES N OF THE AREA TONIGHT
AND MONDAY...BUT AN INCREASE IN SPEED WILL OCCUR MONDAY OVER THE
OHIO VALLEY AND SPREAD ACROSS THE STATE MON NIGHT. THIS WILL
TRANSPORT A LITTLE MOISTURE UP OVER THE SFC/UPPER RIDGE...BUT NOT
MUCH AT ALL. WESTERLY/UPSLOPE FLOW WILL HELP ADD LOW-LEVEL LIFT.
THE QPF GENERATED BY ALL THE MODELS AND IN THE SREF PLUMES IS LESS
THAN A TENTH - EVEN IN THOSE UPSLOPE AREAS. SO...WHILE VERY LIGHT
SNOW IS LIKELY IN THE WEST NEW YEARS EVE/NIGHT DUE TO THE
PERSISTENT CONSENSUS AMONG THE MDLS...THE ACCUMS WILL BE ALMOST
NIL. DRYING ON THE NWRLY WINDS AND BEHIND THE STRENGTHENING JET
STREAK WILL DECREASE THE POPS ON TUES...BUT -14C AIR CROSSING THE
LAKES WILL GENERATE SOME LAKE EFFECT SHSN DOWNWIND.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
LATEST MED RANGE GUID BACKS OFF ON THE MAGNITUDE/COLDNESS OF THE
AIR MASS MOVING INTO THE NERN U.S. THIS WEEK. THUS...HAVE BUMPED
UP THE TEMPS SLIGHTLY FOR THE LONG TERM. BUT THE NW FLOW
CONTINUES...AND NOTHING ELSE WAS CHANGED WITH THE OVERNIGHT PKG.
PREV DISC FOLLOWS...
LAKE ENHANCED BANDS SHOULD CONTINUE THROUGH WEDNESDAY
MORNING...AND PERHAPS WEDNESDAY AFTERNOON. A FEW NORTHERN STREAM
FEATURES WILL CROSS THE LOWER GREAT LAKES AROUND MID-WEEK AND MAKE
LAKE EFFECT SHOWERS. AN ARCTIC AIR MASS BEGINS TO MOVE THROUGH
SOUTHERN CANADA AND DECREASING 850MB TEMPERATURES WILL CONTINUE
THROUGH THE LATTER HALF OF THE WEEK. CURRENT RUNS HAVE PA UNDER
M16C TEMPERATURES AT 850MB THURSDAY MORNING. THE GFS AND EC
PROPAGATE ANOTHER TROUGH THROUGH PENNSYLVANIA FRIDAY. THE EC
SPEEDS UP THIS TROUGH AS THE GFS SLOWS THE SYSTEM DOWN. THE
MOVEMENT OF THE LARGE UPPER LEVEL LOW DRIVING THIS SUCCESSIVE
SHORT WAVE TROUGHS VARIES BETWEEN THE MODELS. THE EC MOVES IT
QUICKER THROUGH NOVA SCOTIA AND THEN EXITING TO THE NORTHEAST. THE
GFS SLOWS IT DOWN ON A MORE EASTERLY TRACK. EITHER WAY...EXPECT
HIGH TEMPERATURES THIS WEEK TO BE AT OR BELOW FREEZING...MONDAY
AND TUESDAY BEING THE WARMEST DAYS. HIGHS AFTER THE TROUGH PASSAGE
INTO TUESDAY WILL HAVE HIGHS IN THE UPPER TEENS BY THE END OF THE
UP COMING WEEK. COUPLE THE LOW TEMPS WITH THE GUSTY FLOW...AND
WIND CHILLS COULD BE AN ISSUE DURING THIS TIME FRAME. LOWS THROUGH
THE LATER HALF OF THE WEEK SHOULD BE IN THE LOW TEENS.
&&
.AVIATION /17Z SUNDAY THROUGH THURSDAY/...
NW UPSLOPE FLOW WILL KEEP IFR/MVFR CIGS AND SCT SNOW SHOWERS ACROSS
THE NW MTNS AND LAUREL HIGHLANDS THROUGH MUCH OF THE DAY. VFR TO
OCCASIONALLY MVFR IN -SNSH ACROSS THE CENTRAL MTN TERMINALS /AOO
AND UNV/. FARTHER EAST...CONDS HAVE RETURNED TO VFR...WITH EVEN
SOME BREAKS IN THE OVC.
WINDS ARE A PROBLEM ACROSS THE REGION...WITH BLUSTERY NW WINDS
OCCASIONALLY GUSTING OVER 30 MPH.
-SHSN ACTIVITY SHOULD TAPER OFF OVER NIGHT...ALTHOUGH CLOUDS MAY
LINGER ACROSS THE WEST.
OUTLOOK...
MON...VFR EAST...BECOMING VFR WEST.
MON NIGHT-TUES...SOME MVFR POSS...WITH LIGHT SNOW DEVELOPING.
WED-THU...GENERALLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR
PAZ024-033.
WIND ADVISORY UNTIL 3 PM EST THIS AFTERNOON FOR PAZ024>026-
033>036-056-057-059-063>066.
&&
$$
SYNOPSIS...GRUMM/DANGELO
NEAR TERM...GRUMM/DANGELO
SHORT TERM...GRUMM/DANGELO
LONG TERM...DANGELO/CERU
AVIATION...GRUMM/EVANEGO