Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 12/27/12
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
309 PM EST TUE DEC 25 2012
...SEVERE STORMS INCLUDING A FEW TORNADOES LIKELY LATE TUES
NIGHT/WED MORNING...
.SHORT TERM /TONIGHT THROUGH THURSDAY/...
INGREDIENTS STILL COMING TOGETHER FOR NOCTURNAL SEVERE WEATHER EVENT
AFTER MIDNIGHT TONIGHT. 12Z RUNS HAVE CONTINUED TREND OF MORE
FAVORABLE PARAMETERS. 0-1KM BULK SHEAR OF 45-55KT NOW IN BOTH NAM
AND GFS...THOUGH THESE ARE SOMEWHAT EAST OF BEST MOISTURE/CAPE AXIS.
IN SPITE OF THIS...FCST SIG TOR PARAMETER VALUES ARE NOW 1.5-2.5 IN
GFS AND 4-5 WITH THE NAM. TORNADO THREAT IS QUITE HIGH FOR A COOL
SEASON QLCS EVENT.
TIMING ON GFS AND ECMWF HAS SHIFTED SLIGHTLY BACK TO BETTER MATCH
THE SLOWER NAM. LATEST HRRR NOW SIMILAR TO GFS TIMING. DUE TO
UNCERTAINTY IN MODELS AND WHETHER ANY PREFRONTAL STORM ACTIVITY WILL
DEVELOP...HAVE NOT TWEAKED TIMING BACK TOO MUCH. TOTAL RAINFALL
STILL HARD PRESSED TO EXCEED 2 INCHES. NO SIGNIFICANT FLOODING
PROBLEMS EXPECTED.
AFTER FRONT PASSES...PRECIP SHOULD END QUICKLY. WILL BE ISSUING A
WIND ADVISORY FOR THE ENTIRE AREA BUT STARTING A LITTLE SOONER IN
THE MOUNTAINS AS LOW LEVEL FLOW OF 50KTS COULD MIX DOWN TO HIGHER
ELEVATIONS. ALSO HAVE CONTINUED SLT CHC/CHC RAIN/SNOW SHOWER MIX
OVER PARTS OF FAR NE GA WED NIGHT. SHOULD NOT SEE ANY ACCUMULATION.
REST OF FCST LOOKS GOOD. WE WILL CONTINUE TO MONITOR THE SITUATION.
SNELSON
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
THE LONG TERM PORTION OF THE FORECAST BEGINS WITH WRAP AROUND
MOISTURE FROM THE BACK SIDE OF THE EXITING LOW PRESSURE SYSTEM
ACROSS N GA. COOLER AIR WILL ALSO BE FILTERING INTO THE STATE BUT IT
LOOKS LIKE THE BETTER MOISTURE WILL STAY FAR ENOUGH NORTH THAT IT
SHOULD NOT CAUSE ANY WINTER PRECIP ACROSS THE N GA MOUNTAINS THU
NIGHT/FRIDAY MORNING. HIGH PRESSURE BUILDS IN THURSDAY WITH MOISTURE
BEGINNING TO RETURN TO THE REGION FRIDAY. MOISTURE BEGINS PUSHING IN
AHEAD OF NEXT SYSTEM WHICH WILL BRING ANOTHER ROUND OF PRECIP TO THE
STATE FRIDAY NIGHT/SATURDAY. THIS NEXT SYSTEM DOES NOT LOOK AS
STRONG AS THE ONE THAT WILL MOVE THROUGH TONIGHT...SO WILL CONTINUE
WITH ONLY SHOWERS FOR NOW. THE MODELS SHOW THIS SECOND SYSTEM MOVING
THROUGH THE AREA VERY FAST WITH THE RAIN MOVING INTO W GA AROUND 06Z
SAT AND THE ENTIRE SYSTEM EXITING THE EAST SIDE OF THE STATE BY 18Z
SAT. A STRONG HIGH PRESSURE RIDGE BUILDS IN BEHIND THIS SECOND
SYSTEM AND IT LOOKS TO KEEP NORTH AND CENTRAL GEORGIA DRY SUNDAY AND
MONDAY.
01
&&
.HYDROLOGY...
FLASH FLOOD GUIDANCE REMAINS IN THE 1.5/2.5/3.0 FOR 1H 3H 6H
GUIDANCE RESPECTIVELY. THESE ARE SLIGHTLY REDUCED VALUES WITH RECENT
RAINS BUT LIKELY NOT SUFFICIENT FOR SIGNIFICANT FLOODING CONCERNS
GIVEN INITIAL LIGHT TO MODERATE RAIN AHEAD OF SYSTEM AND THEN
RAPID MOVEMENT OF COLD FRONT ONCE CONVECTIVELY ENHANCED BANDS SET
UP. STILL WILL BE CLOSELY MONITORING THE NEXT 24 HOUR FOR ANY
SHORT FUSE RIVER AND STREAM WARNINGS PRIMARILY.
&&
.AVIATION...
18Z UPDATE...
LIFR CIGS/VSBYS HAVE BEEN SLOW TO IMPROVE TODAY. AREA OF RAIN
SPREADING NORTH THIS AFTERNOON MAY HELP IMPROVE CONDITIONS BUT
NOT MUCH. SCT SHRA LIKELY TONIGHT AFTER INITIAL ROUND OF RAIN
BEFORE MAIN LINE OF SHRA/TSRA MOVES IN FROM THE WEST. HAVE ADDED
PREVAILING TSRA FROM 08-12Z TO TAFS TO PROVIDE CLARITY AND
CONFIDENCE IN FCST. A FEW STORMS COULD BE STRONG. SFC WINDS WILL
SWITCH TO SW THEN W AFTER THE STORMS MOVE THRU AND WILL GUST TO
30KTS IN THE AFTERNOON.
//ATL CONFIDENCE...18Z UPDATE...
MEDIUM CONFIDENCE ON TIMING OF CIGS/VSBYS TODAY AND TSRA TONIGHT.
HIGH CONFIDENCE ON ALL OTHER ELEMENTS.
SNELSON
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 49 52 31 51 / 100 80 0 5
ATLANTA 49 49 30 49 / 100 20 0 5
BLAIRSVILLE 46 48 28 45 / 100 80 20 5
CARTERSVILLE 49 50 31 46 / 100 20 0 5
COLUMBUS 50 51 33 53 / 100 20 0 5
GAINESVILLE 47 50 31 48 / 100 60 0 5
MACON 55 55 33 54 / 100 60 0 5
ROME 48 49 32 47 / 100 20 5 5
PEACHTREE CITY 49 49 31 50 / 100 20 0 5
VIDALIA 59 60 36 56 / 80 80 0 0
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY FROM 10 AM TO 10 PM EST WEDNESDAY FOR THE
FOLLOWING ZONES: BALDWIN...BANKS...BARROW...BARTOW...BIBB...
BLECKLEY...BUTTS...CARROLL...CHATTAHOOCHEE...CHEROKEE...CLARKE...
CLAYTON...COBB...COWETA...CRAWFORD...CRISP...DAWSON...DEKALB...
DODGE...DOOLY...DOUGLAS...EMANUEL...FAYETTE...FLOYD...FORSYTH...
GLASCOCK...GREENE...GWINNETT...HALL...HANCOCK...HARALSON...
HARRIS...HEARD...HENRY...HOUSTON...JACKSON...JASPER...
JEFFERSON...JOHNSON...JONES...LAMAR...LAURENS...MACON...
MADISON...MARION...MERIWETHER...MONROE...MONTGOMERY...MORGAN...
MUSCOGEE...NEWTON...NORTH FULTON...OCONEE...OGLETHORPE...
PAULDING...PEACH...PICKENS...PIKE...POLK...PULASKI...PUTNAM...
ROCKDALE...SCHLEY...SOUTH FULTON...SPALDING...STEWART...SUMTER...
TALBOT...TALIAFERRO...TAYLOR...TELFAIR...TOOMBS...TREUTLEN...
TROUP...TWIGGS...UPSON...WALTON...WARREN...WASHINGTON...
WEBSTER...WHEELER...WILCOX...WILKES...WILKINSON.
WIND ADVISORY FROM 1 AM TO 10 PM EST WEDNESDAY FOR THE FOLLOWING
ZONES: CATOOSA...CHATTOOGA...DADE...FANNIN...GILMER...GORDON...
LUMPKIN...MURRAY...TOWNS...UNION...WALKER...WHITE...WHITFIELD.
&&
$$
SHORT TERM...SNELSON
LONG TERM....01
AVIATION...SNELSON
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
406 PM EST TUE DEC 25 2012
.SHORT TERM...
TONIGHT THROUGH WEDNESDAY NIGHT...
SIGNIFICANT WINTER STORM TO IMPACT MUCH OF THE CWA IN THE SHORT
TERM. WATER VAPOR IMAGERY SHOWING POTENT UPPER LOW DIGGING THROUGH
TEXAS. 12Z RAOB AND LATEST RAP ANALYSIS HAS 100KT+ UPPER JET COMING
INTO THE BASE OF THE TROUGH. ASSOCIATED SFC LOW NEAR TX/LA BORDER AT
18Z AND IS EXPECTED TO LIFT NE INTO THE CENTRAL TN VALLEY BY 12Z
WED. GOOD ISENT ASCENT AHEAD OF THIS SYSTEM ALONG THE 290-295K SFC
IS EXPECTED TO INITIATE PRECIP IN THE FAR SOUTHERN CWA AFTER
MIDNIGHT TONIGHT WITH LARGE SCALE FORCING TO INTENSIFY PRECIP TO
MOD-HVY SNOW AFTER 12Z. DESPITE A TREND TO A MORE SE TRACK...GOOD
DEFORMATION AXIS STILL SETS UP OVER SE CWA ALONG WITH SUBSTANTIAL
HEIGHT FALLS IN A DEEP MOISTURE COLUMN TO SUPPORT A WINDOW OF
OPPORTUNITY FOR WARNING CRITERIA SNOWFALL. STRONG GRADIENT BRINGING
15 TO 25 MPH WINDS WITH GUSTS TO 30 MPH LENDS FURTHER CREDENCE IN
MAINTAINING WINTER STORM WARNING. HAD TRANSITIONED REMAINING
COUNTIES IN THE WATCH OVER TO AN ADVISORY WITH GENERALLY 1-3/2-4
INCH AMOUNTS BUT ALSO ACCOMPANIED BY GUSTY WINDS FOR BLOWING SNOW.
POTENTIAL FOR MOD-HVY SNOW WILL BE SHORT-LIVED HOWEVER AS SYSTEM
WILL QUICKLY EXIT TOWARD THE EAST COAST WEDNESDAY NIGHT.
&&
.LONG TERM...
THURSDAY THROUGH TUESDAY...THE CHALLENGES THIS PERIOD INCLUDE
CHANCES FOR SNOW WITH THE PASSAGE OF A WEAK UPPER TROF LATE THIS
WEEK. ALSO...HIGH AND LOW TEMPERATURES WITH AN EXTENDED PERIOD OF
COLD AIR AND SNOW COVER OVER AT LEAST PART OF THE FORECAST AREA WILL
PROVIDE ADDITIONAL CHALLENGES. FOR THIS PACKAGE...FAVORED THE GFS.
THE GFS HAS AT LEAST AS GOOD OF RUN TO RUN CONSISTENCY AS THE ECMWF
AND APPEARS TO BE HANDLING THIS PATTERN REASONABLY WELL. THE GFS
TIMING OF THE SYSTEM LATE THIS WEEK HAS ALSO BEEN CONSISTENT FOR THE
PAST 8 RUNS AND APPEARS ON TRACK. ALSO...THE OPERATION MOS AND
ENSEMBLE MOS HAS BEEN RELATIVELY STABLE IN ITS OUTPUT FOR SEVERAL
DAYS AND APPEARS IN LINE. HAVE MODIFIED HIGH AND LOW TEMPS GIVEN
SNOW FIELD CONSIDERATIONS.
AT THE START OF THE PERIOD...DOWNWARD MOTION WILL HAVE INCREASED
SIGNIFICANTLY AS EVIDENCE OF NET ISENTROPIC ADIABATIC OMEGA WITH A
DRYING OF THE MID LEVELS. AS A RESULT...HAVE REMOVED LINGERING
FLURRIES THURSDAY OVER NW OHIO. FOR THE REST OF THE PERIOD...TRIED
TO PUT SOME DETAIL IN THE TIMING OF THE UPPER LEVEL TROF THIS
WEEKEND AND SUBSEQUENT LAKE EFFECT SNOW SHOWERS. THERE IS LITTLE
MOISTURE TO WORK WITH AND FORCING IS WEAK...SO ANY SNOW AMOUNTS
SHOULD BE LIGHT. LAKE EFFECT PARAMETERS ARE VERY MARGINAL WITH A
LIMITED FETCH. DELTA T VALUES GENERALLY SHOULD BE 10 TO 14 WITH LOW
INVERSION HEIGHTS. REMOVED THE CHANCE FOR SNOW SUNDAY AND SUNDAY
NIGHT. GFS BUFKIT PROFILE SUPPORTS FREEZING DRIZZLE OVER SNOW GIVEN
THE LACK OF ICE INDUCED IN THE CLOUD LAYER. TEMPERATURES IN A DEEP
LAYER WARM ABOVE -10C. NOT OPTIMISTIC ABOUT SNOW CHANCES MONDAY...
BUT FOR THE SAKE OF CONSISTENCY AND LINGERING UNCERTAINTY ABOUT
EARLY NEXT WEEK...LEFT LAKE EFFECT SNOW SHOWERS IN THE FORECAST
MONDAY.
&&
.AVIATION...
12Z TAFS...DRIER LOW LEVEL AIR HAS WORKED INTO MUCH OF NORTH
CENTRAL INDIANA RESULTING IN SCATTERING OF LOW CLOUDS AT KSBN.
SATELLITE TRENDS SUGGEST THIS CLEARING MAY REACH KFWA OVER NEXT
FEW HOURS BUT CONFIDENCE IN ANY SUSTAINED BREAKS IS LOW AS
NORTHEAST FLOW TRAJECTORIES OFF SOUTHERN LAKE HURON/LAKE ERIE
MAY ACT TO MAINTAIN STRATOCU THROUGH THE DAY. WILL KEEP VFR
CONDITIONS AT KFWA FOR NOW BUT WILL NEED TO MONITOR TRENDS FOR
POSSIBLE MVFR AMENDMENTS. NORTH WINDS WILL BECOME NORTHEAST TODAY
WITH SPEEDS GENERALLY 10 KNOTS OR LESS. NORTHEAST WINDS TO
STRENGTHEN TONIGHT AS SFC LOW PRESSURE DEEPENS TO THE SOUTH IN
ASSOCIATION WITH STORM SYSTEM TO IMPACT THE AREA FOR WEDNESDAY. A
LIGHT SNOW MENTION WAS ADDED TO KFWA TOWARD THE END OF THE
PERIOD...BUT CONDITIONS WILL DETERIORATE RAPIDLY AT KFWA JUST
BEYOND THIS FORECAST PERIOD AS HEAVIER SNOW MOVES IN FROM THE SOUTH.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WINTER STORM WARNING FROM 7 AM WEDNESDAY TO 1 AM EST THURSDAY
FOR INZ009.
WINTER STORM WARNING FROM 4 AM TO 10 PM EST WEDNESDAY FOR INZ018-
025>027-032>034.
WINTER WEATHER ADVISORY FROM 7 AM WEDNESDAY TO 1 AM EST THURSDAY
FOR INZ005>008.
WINTER WEATHER ADVISORY FROM 4 AM TO 10 PM EST WEDNESDAY FOR
INZ015>017-020-022>024.
MI...WINTER WEATHER ADVISORY FROM 7 AM WEDNESDAY TO 1 AM EST THURSDAY
FOR MIZ079>081.
OH...WINTER STORM WARNING FROM 7 AM WEDNESDAY TO 1 AM EST THURSDAY
FOR OHZ001-002-004-005.
WINTER STORM WARNING FROM 4 AM TO 10 PM EST WEDNESDAY FOR OHZ015-
016-024-025.
LM...SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 7 PM EST THURSDAY
FOR LMZ043-046.
&&
$$
SHORT TERM...JAL
LONG TERM...SKIPPER
AVIATION...JAL
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1045 AM MST TUE DEC 25 2012
.UPDATE...
ISSUED AT 821 AM MST TUE DEC 25 2012
AFTER CLOSER EXAMINATION OF LATEST RUC AND NAM DATA...CONCERNED
ABOUT POCKET OF NEGATIVE EPV* VALUES GRADUALLY MOVING INTO THE
AREA FROM THE EAST. THIS AREA OF POTENTIAL INSTABILITY CORRELATES
WELL WITH AREA OF ENHANCED REFLECTIVITY ACROSS THE CENTER OF THE
CWA WHICH HAS HAD SEVERAL LOCATIONS REPORTING 1/2SM IN SNOW. THIS
WILL GRADUALLY SHIFT SOUTH AND DIMINISH AS LARGE SCALE FORCING ENDS.
WHILE I DO NOT EXPECT TO SEE LARGE SNOW AMOUNTS DUE TO THE SHORT
EXPECTED DURATION...WITH POTENTIALLY UNSTABLE CONDITIONS HAVE
CONCERNS THAT THERE WILL BE A FEW POCKETS OF LOCALLY HIGH AMOUNTS
AROUND 4 INCHES. WHILE 4 INCH AMOUNTS ARE NOT EXPECTED TO BE
WIDESPREAD...THINK CURRENT DATA SUPPORTS WINTER WEATHER ADVISORY
FOR THE REST OF THE DAY. WHILE CONDITIONS ARE MARGINAL...THINK
WITH MANY PEOPLE TRAVELING SOMEWHAT RELAXED CRITERIA WARRANTED.
UPDATE ISSUED AT 639 AM MST TUE DEC 25 2012
BASED ON VERY HIGH SNOW TO LIQUID RATIOS OBSERVED AT OFFICE...HAVE
UPPED SNOW AMOUNTS TO BE MORE IN LINE WITH HIGHER RATIOS. STILL
KEEPS FORECAST IN 1 TO 3 INCH RANGE...BUT DID RESULT IN ABOUT AN
INCH HIGHER AMOUNTS FORECAST ACROSS NORTHEAST CWA.
&&
.SHORT TERM...(TODAY THROUGH THURSDAY NIGHT)
ISSUED AT 404 AM MST TUE DEC 25 2012
LIGHT SNOW WILL CONTINUE TO SPREAD ACROSS THE FORECAST AREA THIS
MORNING BEFORE DIMINISHING RAPIDLY BY LATE AFTERNOON AS THE LOW
PRESSURE SYSTEM MOVES THROUGH TEXAS AND COLD SURFACE HIGH
PRESSURE PUSHES FURTHER SOUTH INTO THE CENTRAL AND SOUTHERN HIGH
PLAINS BY LATE TODAY. STILL EXPECT ONE TO THREE INCHES OF
ACCUMULATIONS ACROSS THE FORECAST AREA.
COLD AND DRY CONDITIONS ARE EXPECTED TONIGHT AND WEDNESDAY WITH
THE COLD AREA OF HIGH PRESSURE AT THE SURFACE MOVING FURTHER
EAST...ALLOWING THE WESTERN SECTIONS OF THE FORECAST AREA TO BEGIN
WARMING AS SHORT WAVE RIDGING MOVES OVER THE REGION.
THE INITIAL SHORT WAVE TROUGH AT THE LEADING EDGE OF THE MAIN
UPPER TROUGH DEEPENING OVER THE WESTERN UNITED STATES MOVES EAST
ACROSS THE CENTRAL HIGH PLAINS ON THURSDAY. ANOTHER ROUND OF LIGHT
SNOW IS POSSIBLE WITH THE PRIMARY ACCUMULATIONS OCCURRING MAINLY
OVER THE NORTHERN SECTIONS OF THE FORECAST AREA.
.LONG TERM...(FRIDAY THROUGH TUESDAY)
ISSUED AT 1222 AM MST TUE DEC 25 2012
THE PERIOD BEGINS WITH A TROUGH AXIS ACROSS THE CENTRAL PLAINS ON
FRIDAY. HOWEVER MOISTURE WILL BE LACKING DUE TO DEEP WESTERLY FLOW
AND THE MAIN ENERGY WITH THE SYSTEM WILL BE TO THE SOUTH...SO LEFT
IT DRY. SHORTWAVE RIDGING WILL FOLLOW FOR THE WEEKEND WITH
CONTINUED DRY CONDITIONS. ANOTHER SHORTWAVE TROUGH APPROACHES FOR
EARLY NEXT WEEK...HOWEVER A SPLIT UPPER FLOW SUGGESTS MINIMAL
PRECIPITATION CHANCES WITH IT AS WELL. TEMPERATURES FOR THE PERIOD
WILL HAVE SOME MINOR FLUCTUATIONS...BUT GENERALLY BE AROUND 10
DEGREES BELOW NORMAL.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1040 AM MST TUE DEC 25 2012
CONDITIONS CONTINUE TO VARY BETWEEN HIGH MVFR/VFR TO IFR CONDITIONS
AS PERIODS OF SNOW CONTINUE TO IMPACT BOTH TAF SITES. GIVEN
OVERALL RADAR PATTERN AND EXPECTED CHANGES TO FORCING FOR THE NEXT
FEW HOURS EXPECT THIS TREND TO CONTINUE AT KGLD WHILE CONDITIONS
AS SNOW CONTINUES TO DIMINISH AT MCK. SNOW SHOULD GENERALLY END
AROUND 21Z WITH CIGS RAISING THROUGH THE EARLY EVENING. POINT
SOUNDINGS INDICATE POTENTIAL FOR FOG OVERNIGHT AS WINDS BECOME
LIGHT AND STRONG SUBSIDENCE MAY BRING A PERIOD OF CLEARING. NOT
SURE IF THIS IS JUST MODELS RESPONDING TO CURRENT SNOW FIELD BUT
IF SOUNDINGS VERIFY WE MAY NOT ONLY SEE FOG BUT PERSISTENT
FLURRIES/ICE CRYSTALS THROUGH THE NIGHT.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...WINTER WEATHER ADVISORY UNTIL 5 PM MST /6 PM CST/ THIS AFTERNOON
FOR KSZ001>003-013>015-027>029-041-042.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...JRM
SHORT TERM...LOCKHART
LONG TERM...024
AVIATION...JRM
AREA FORECAST DISCUSSION
NWS GOODLAND KS
838 AM MST TUE DEC 25 2012
.UPDATE...
ISSUED AT 821 AM MST TUE DEC 25 2012
AFTER CLOSER EXAMINATION OF LATEST RUC AND NAM DATA...CONCERNED
ABOUT POCKET OF NEGATIVE EPV* VALUES GRADUALLY MOVING INTO THE
AREA FROM THE EAST. THIS AREA OF POTENTIAL INSTABILITY CORRELATES
WELL WITH AREA OF ENHANCED REFLECTIVITY ACROSS THE CENTER OF THE
CWA WHICH HAS HAD SEVERAL LOCATIONS REPORTING 1/2SM IN SNOW. THIS
WILL GRADUALLY SHIFT SOUTH AND DIMINISH AS LARGE SCALE FORCING ENDS.
WHILE I DO NOT EXPECT TO SEE LARGE SNOW AMOUNTS DUE TO THE SHORT
EXPECTED DURATION...WITH POTENTIALLY UNSTABLE CONDITIONS HAVE
CONCERNS THAT THERE WILL BE A FEW POCKETS OF LOCALLY HIGH AMOUNTS
AROUND 4 INCHES. WHILE 4 INCH AMOUNTS ARE NOT EXPECTED TO BE
WIDESPREAD...THINK CURRENT DATA SUPPORTS WINTER WEATHER ADVISORY
FOR THE REST OF THE DAY. WHILE CONDITIONS ARE MARGINAL...THINK
WITH MANY PEOPLE TRAVELING SOMEWHAT RELAXED CRITERIA WARRANTED.
UPDATE ISSUED AT 639 AM MST TUE DEC 25 2012
BASED ON VERY HIGH SNOW TO LIQUID RATIOS OBSERVED AT OFFICE...HAVE
UPPED SNOW AMOUNTS TO BE MORE IN LINE WITH HIGHER RATIOS. STILL
KEEPS FORECAST IN 1 TO 3 INCH RANGE...BUT DID RESULT IN ABOUT AN
INCH HIGHER AMOUNTS FORECAST ACROSS NORTHEAST CWA.
&&
.SHORT TERM...(TODAY THROUGH THURSDAY NIGHT)
ISSUED AT 404 AM MST TUE DEC 25 2012
LIGHT SNOW WILL CONTINUE TO SPREAD ACROSS THE FORECAST AREA THIS
MORNING BEFORE DIMINISHING RAPIDLY BY LATE AFTERNOON AS THE LOW
PRESSURE SYSTEM MOVES THROUGH TEXAS AND COLD SURFACE HIGH
PRESSURE PUSHES FURTHER SOUTH INTO THE CENTRAL AND SOUTHERN HIGH
PLAINS BY LATE TODAY. STILL EXPECT ONE TO THREE INCHES OF
ACCUMULATIONS ACROSS THE FORECAST AREA.
COLD AND DRY CONDITIONS ARE EXPECTED TONIGHT AND WEDNESDAY WITH
THE COLD AREA OF HIGH PRESSURE AT THE SURFACE MOVING FURTHER
EAST...ALLOWING THE WESTERN SECTIONS OF THE FORECAST AREA TO BEGIN
WARMING AS SHORT WAVE RIDGING MOVES OVER THE REGION.
THE INITIAL SHORT WAVE TROUGH AT THE LEADING EDGE OF THE MAIN
UPPER TROUGH DEEPENING OVER THE WESTERN UNITED STATES MOVES EAST
ACROSS THE CENTRAL HIGH PLAINS ON THURSDAY. ANOTHER ROUND OF LIGHT
SNOW IS POSSIBLE WITH THE PRIMARY ACCUMULATIONS OCCURRING MAINLY
OVER THE NORTHERN SECTIONS OF THE FORECAST AREA.
.LONG TERM...(FRIDAY THROUGH TUESDAY)
ISSUED AT 1222 AM MST TUE DEC 25 2012
THE PERIOD BEGINS WITH A TROUGH AXIS ACROSS THE CENTRAL PLAINS ON
FRIDAY. HOWEVER MOISTURE WILL BE LACKING DUE TO DEEP WESTERLY FLOW
AND THE MAIN ENERGY WITH THE SYSTEM WILL BE TO THE SOUTH...SO LEFT
IT DRY. SHORTWAVE RIDGING WILL FOLLOW FOR THE WEEKEND WITH
CONTINUED DRY CONDITIONS. ANOTHER SHORTWAVE TROUGH APPROACHES FOR
EARLY NEXT WEEK...HOWEVER A SPLIT UPPER FLOW SUGGESTS MINIMAL
PRECIPITATION CHANCES WITH IT AS WELL. TEMPERATURES FOR THE PERIOD
WILL HAVE SOME MINOR FLUCTUATIONS...BUT GENERALLY BE AROUND 10
DEGREES BELOW NORMAL.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 404 AM MST TUE DEC 25 2012
CONDITIONS WILL VARY BETWEEN IFR AND MVFR AT MCK AND GLD THROUGH
THE MORNING AS LIGHT SNOW CONTINUES TO FALL ACROSS THE CENTRAL
HIGH PLAINS REGION. LIGHT SNOW WILL DIMINISH FROM WEST TO EAST
THROUGH THE AFTERNOON. AFTER 21Z...CONDITIONS AT GLD WILL BECOME
MVFR WITH VFR CONDITIONS EXPECTED AFTER 06Z. MCK WILL TRANSITION
TO VFR BETWEEN 21Z AND 00Z WITH A POSSIBLE RETURN OF MVFR
CONDITIONS AFTER 09Z WITH FOG AND LOW CEILINGS.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...WINTER WEATHER ADVISORY UNTIL 5 PM MST /6 PM CST/ THIS AFTERNOON
FOR KSZ001>003-013>015-027>029-041-042.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...JRM
SHORT TERM...LOCKHART
LONG TERM...024
AVIATION...LOCKHART
AREA FORECAST DISCUSSION
NWS PADUCAH KY
319 PM CST TUE DEC 25 2012
.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...
ISSUED AT 318 PM CST TUE DEC 25 2012
IN THE NEAR TERM...AN INTENSIFYING BAND OF MIXED PRECIPITATION IS
LIFTING NORTHWARD FROM NORTHERN ARKANSAS AS OF 20Z. THIS BAND IS
ASSOCIATED WITH STRONG WARM ADVECTION ON EASTERLY FLOW IN THE
850/700 MB LAYER. RUC MODEL BRINGS THE ZONE OF STRONG MID LEVEL
WARM ADVECTION AND ASSOCIATED PRECIP INTO SOUTHEAST MISSOURI BY
00Z. PRECIP TYPE WILL GRADUALLY CHANGE TO SNOW BY MID EVENING IN
SE MISSOURI...ONCE THE WARM ADVECTION DIMINISHES AND FRONTOGENETIC
FORCING TAKES OVER. INTERESTING TO NOTE THAT RUC MODEL THERMAL
PROFILES ARE SOMEWHAT COLDER THAN GFS/NAM PROFILES THIS EVENING.
LATER IN THE EVENING...IN THE 03Z TO 06Z TIME FRAME...RUC
INDICATES THE MAIN FORCING MECHANISM WILL BECOME MID LEVEL
FRONTOGENESIS /850 TO 700 MB LAYER/. THIS WILL RESULT IN LOCALLY
HEAVY PRECIPITATION ACQUIRING MORE OF A BANDED CHARACTER AS IT
OVERSPREADS THE REMAINDER OF THE FORECAST AREA.
LOOKING AT THE 12Z MODEL SUITE...MODELS ARE ALMOST IN LOCKSTEP AS
THE EVENT IS NOW WITHIN THE NEXT 24 HOURS. THE PRIMARY ISSUES ARE
PRECIPITATION TYPE AND LOCATION OF THE DEFORMATION ZONE /HEAVIEST
QPF/.
THE SWATH OF HEAVIEST QPF IS EXPECTED TO OCCUR UNDER THE DEFORMATION
ZONE TO THE NORTHWEST OF THE MID LEVEL LOW. AN INTENSE/COMPACT 500
MB LOW WILL TRACK EAST/NORTHEAST ACROSS TENNESSEE TONIGHT AND
WEDNESDAY. THE ASSOCIATED DEFORMATION ZONE WILL BE ACROSS SE
MISSOURI AND ROUGHLY ALONG AND NORTHWEST OF THE OHIO RIVER. THIS IS
EVIDENT IN THE 12Z GFS...WHICH SHOWS PRONOUNCED MID LEVEL
FRONTOGENETICAL FORCING AND HEAVY QPF COLOCATED WITH EACH OTHER. MOST
OTHER MODEL QPF GUIDANCE INDICATES THE DEFORMATION ZONE LOCATION
IN THE SAME AREA. THEREFORE...EXPECT THE SWATH OF HEAVIEST
SNOWFALL TO OCCUR WITHIN THAT AREA...MAINLY NW OF A KEVV/KPAH LINE.
ONE MAJOR CAVEAT IS PRECIP TYPE. THE MODELS HAVE ACTUALLY WARMED
SOMEWHAT IN THE 800 TO 900 MB LAYER TONIGHT DUE TO PRONOUNCED
EASTERLY FLOW AT 850 MB. ABOVE FREEZING AIR IS FORECAST TO WRAP
WESTWARD AROUND THE TOP OF THE 850 MB LOW...WHICH WILL DELAY THE
CHANGEOVER TO SNOW ALONG AND EAST OF THE KEVV/KPAH CORRIDOR. BASED
ON A BLEND OF SREF/NAM/GFS THERMAL PROFILES...THE CHANGEOVER TO SNOW
FROM KPAH TO KEVV WOULD BE IN THE 07Z TO 11Z TIME FRAME. THIS WOULD
CUT DOWN SIGNIFICANTLY ON FORECAST SNOWFALL AMOUNTS...THOUGH A FEW
HOURS OF HEAVY WET SNOW AND BLIZZARD CONDITIONS ARE STILL EXPECTED.
MODEL BOUNDARY LAYER AND 850 MB TEMPS IN THE FAR SOUTHEAST DO NOT
SUPPORT MUCH SNOW IN THE KHOP AREA...AND THE WINTER STORM WATCH
HAS BEEN DISCONTINUED FOR THAT AREA.
WHERE THE BULK OF THE PRECIPITATION IS ALL SNOW NORTH AND WEST OF
THE KEVV/KPAH CORRIDOR...THERE IS HIGH CONFIDENCE IN A CRIPPLING
BLIZZARD. SNOWFALL AMOUNTS WITHIN THE DEFORMATION ZONE AXIS SHOULD
REACH A FOOT OR SO. LOOKING AT BUFKIT MOMENTUM TRANSFER...BOTH THE
NAM AND GFS INDICATE A HIGH POTENTIAL FOR GUSTS TO AT LEAST 35
KNOTS. THE SREF SHOWS A 50 PERCENT CHANCE OF SUSTAINED WINDS OVER 25
KNOTS IN SE MISSOURI. DESPITE THE HEAVY WET NATURE OF THE
SNOW...DRIFTS WILL BE MEASURED IN FEET IN THE SWATH OF HEAVIEST
SNOW. THE COMBINATION OF HEAVY WET SNOW AND WIND WILL LIKELY CAUSE
SOME POWER OUTAGES.
AS FOR THE TIMING OF THE EVENT...PRECIP WILL SPREAD NORTH ACROSS
THE ENTIRE FORECAST AREA THROUGH 06Z. THE HEAVIEST PRECIP WILL
OCCUR ROUGHLY FROM 03Z TO 12Z. THE DEFORMATION ZONE WILL LIFT OUT
WEDNESDAY MORNING...BUT WINDS WILL NOT BEGIN TO DIMINISH UNTIL AT
LEAST 18Z. THE STRONG WINDS WILL CONTINUE TO RESULT IN EXTENSIVE
BLOWING AND DRIFTING IN THE HEAVY SNOW AREA.
.LONG TERM /THURSDAY THROUGH NEXT TUESDAY NIGHT/...
ISSUED AT 318 PM CST TUE DEC 25 2012
IN THE EXTENDED FORECAST PERIOD...SHORTWAVE RIDGING ALOFT WILL
DOMINATE DURING FROM THURSDAY THROUGH THE EARLY MORNING HOURS ON
FRIDAY. ALTHOUGH THERE WILL BE A LITTLE MORE INSOLATION /SUNSHINE/
AVAILABLE...THERE WILL STILL BE WEAK COLD AIR ADVECTION OVER THE
EXPECTED SNOW FIELD FROM THE TUESDAY NIGHT/WEDNESDAY MORNING WINTER
STORM. WITH THIS IN MIND...LOWERED TEMPERATURES 3 TO 5 DEGREES FROM
LIKELY HIGH TEMPERATURES DUE TO CLOUDS...WINDS AND SNOW COVER. THIS
ADJUSTMENT WAS MAINLY DONE OVER AREAS WHERE TWO OR MORE INCHES WERE
EXPECTED IN THE STORM TOTAL SNOWFALL GRIDDED FORECAST ACROSS THE WFO
PAH FORECAST AREA.
BY FRIDAY AFTERNOON...BOTH 12Z ECMWF AND GFS DETERMINISTIC MODEL
GUIDANCE INDICATE SOME ENHANCEMENT OF THE SHORTWAVE TROUGH MOVING
INTO THE WFO PAH FORECAST AREA IN THE SOUTHWESTERLY FLOW BEHIND THE
AFOREMENTIONED SHORTWAVE RIDGE. THE LIFT ASSOCIATED WITH THIS
FEATURE...COMBINED WITH A RESURGENCE OF CANADIAN POLAR AIR /AS WELL
AS ANY ANTECEDENT SNOW COVER/ SHOULD FORCE THE DEVELOPMENT OF LIGHT
WINTRY MIX LATE FRIDAY NIGHT. WITH THIS IN MIND...ATTEMPTED TO LIMIT
AN MEASURABLE SNOW/SLEET POTENTIAL WHERE THERE WAS NOT A MIX WITH
RAIN. AN INITIAL STAB AT SNOW/SLEET AMOUNTS WOULD LEAD TO AMOUNTS
LESS THAN ONE INCH OVER SOUTHEAST MO...SOUTHERN IL....SOUTHWEST IN
AND WESTERN KY ALONG THE OHIO RIVER. SHOULD THE COLDER AIR FILTER IN
FASTER...MAXIMUM AMOUNTS MAY BE CLOSER TO 1.5 INCHES.
SINCE THIS WEATHER SYSTEM LOOKS FOCUSED WITH MORE ISENTROPIC
LIFT...LEFT THE PRECIPITATION ON THE LIGHTER SIDE IN TERMS OF
INTENSITY AND SHORTER IN OVERALL DURATION OF MEASURABLE
PRECIPITATION.
BEYOND SATURDAY...RIDGING ALOFT WILL BUILD BACK INTO THE AREA WITH
SURFACE HIGH PRESSURE AT THE SURFACE. THIS SCENARIO...WITH ANY
ANTECEDENT SNOW COVER...WILL LEAD TOWARD SLIGHTLY COOLER
TEMPERATURES THAN NORMAL OVER SOUTHERN ILLINOIS AND SOUTHWEST
INDIANA THROUGH NEXT TUESDAY.
THERE IS SOME DIFFERENCE IN TIMING OF THE NEXT SOUTHWEST LOW MOVING
TOWARD THE AREA NEXT TUESDAY/WEDNESDAY...WITH THE ECMWF BEING COOLER
AND FASTER AND THE GFS SLOWER AND WARMER. FOR NOW...WILL KEEP THINGS
DRY THROUGH THE REMAINDER OF THIS FORECAST PACKAGE.
&&
.AVIATION...
ISSUED AT 1200 PM CST TUE DEC 25 2012
OR THE 18Z TAF ISSUANCE...PRIMARILY MOVE FROM VFR/MVFR VISIBILITIES
DUE TO CONTINUED MOISTENING OF BOUNDARY LAYER CANADIAN POLAR AIRMASS
ENGULFING THE TAF SITES. FOR THE PERIOD FROM 00Z TO 06Z...MOVE
QUICKLY TOWARD LOW MVFR TO LOWER IFR CATEGORY CEILINGS AS THE
WEATHER SYSTEM SHARPENS AND DEEPENS NEAR KCGI/KPAH TAF SITES. WITH
THE DEFORMATION ZONE NEARBY KCGI/KPAH...DECIDED TO GO WITH HIGH
SUSTAINED WINDS/WIND GUSTS...AS SURFACE WIND GRADIENT WILL BE
LOCALLY HIGHER. AS A CARRYOVER FROM THE 12Z TAFS...KEPT A TEMPORARY
MENTION OF LIFR/VLIFR CEILINGS AND VISIBILITIES...DURING THE MAXIMUM
STORM INTENSITY OVER THESE SITES. FOR THE KEVV AND KOWB TAF
SITES...GIVEN THE SHARP GRADIENT IN PRECIPITATION TYPE...KEPT THESE
LOCATIONS IN MVFR VISIBILITY RAIN THROUGH AT LEAST 09Z DECEMBER
26TH...THEN RAPIDLY CHANGE TO IFR/LIFR CONDITIONS THROUGH 13Z...WITH
A SLOW IMPROVEMENT TO IFR CONDITIONS THROUGH 18Z TUESDAY.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
KY...BLIZZARD WARNING FROM 6 PM THIS EVENING TO NOON CST WEDNESDAY
FOR KYZ001.
WINTER WEATHER ADVISORY FROM 6 AM TO NOON CST WEDNESDAY FOR
KYZ012-017-021-022.
BLIZZARD WARNING FROM MIDNIGHT TONIGHT TO NOON CST WEDNESDAY FOR
KYZ002>011-013>016-018>020.
MO...BLIZZARD WARNING FROM 6 PM THIS EVENING TO NOON CST WEDNESDAY
FOR MOZ076-086-087-100-107>112-114.
IL...BLIZZARD WARNING FROM 6 PM THIS EVENING TO NOON CST WEDNESDAY
FOR ILZ075>078-080>089-092-093.
BLIZZARD WARNING FROM MIDNIGHT TONIGHT TO NOON CST WEDNESDAY FOR
ILZ090-091-094.
IN...BLIZZARD WARNING FROM MIDNIGHT TONIGHT TO NOON CST WEDNESDAY FOR
INZ081-082-085>088.
&&
$$
SHORT TERM...MY
LONG TERM....SMITH
AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS PADUCAH KY
1205 PM CST TUE DEC 25 2012
.UPDATE...
ISSUED AT 1205 PM CST TUE DEC 25 2012
PRELIMINARY THOUGHTS INCORPORATING 12Z NAM/GFS...
MODELS ARE ALMOST IN LOCKSTEP AS THE EVENT IS NOW WITHIN THE NEXT
24 HOURS. THE PRIMARY ISSUES ARE PRECIPITATION TYPE AND LOCATION
OF THE DEFORMATION ZONE /HEAVIEST QPF/.
THE SWATH OF HEAVIEST QPF IS EXPECTED TO OCCUR UNDER THE DEFORMATION
ZONE TO THE NORTHWEST OF THE MID LEVEL LOW. AN INTENSE/COMPACT 500
MB LOW WILL TRACK EAST/NORTHEAST ACROSS TENNESSEE TONIGHT AND
WEDNESDAY. THE ASSOCIATED DEFORMATION ZONE WILL BE ACROSS SE
MISSOURI AND ROUGHLY ALONG AND NORTHWEST OF THE OHIO RIVER. THIS IS
EVIDENT IN THE 12Z GFS...WHICH SHOWS PRONOUNCED MID LEVEL
FRONTOGENETICAL FORCING AND HEAVY QPF COLOCATED WITH EACH OTHER. MOST
OTHER MODEL QPF GUIDANCE INDICATES THE DEFORMATION ZONE LOCATION
IN THE SAME AREA. THEREFORE...EXPECT THE SWATH OF HEAVIEST
SNOWFALL TO OCCUR WITHIN THAT AREA...MAINLY NW OF A KEVV/KPAH LINE.
ONE MAJOR CAVEAT IS PRECIP TYPE. THE MODELS HAVE ACTUALLY WARMED
SOMEWHAT IN THE 800 TO 900 MB LAYER TONIGHT DUE TO PRONOUNCED
EASTERLY FLOW AT 850 MB. ABOVE FREEZING AIR IS FORECAST TO WRAP
WESTWARD AROUND THE TOP OF THE 850 MB LOW...WHICH WILL DELAY THE
CHANGEOVER TO SNOW ALONG AND EAST OF THE KEVV/KPAH CORRIDOR. BASED
ON A BLEND OF SREF/NAM/GFS THERMAL PROFILES...THE CHANGEOVER TO SNOW
FROM KPAH TO KEVV WOULD BE IN THE 07Z TO 11Z TIME FRAME. THIS WOULD
CUT DOWN SIGNIFICANTLY ON FORECAST SNOWFALL AMOUNTS...THOUGH A FEW
HOURS OF HEAVY WET SNOW AND BLIZZARD CONDITIONS ARE STILL EXPECTED.
MODEL BOUNDARY LAYER TEMPS IN THE FAR SOUTHEAST DO NOT SUPPORT MUCH
IF ANY SNOW IN THE KHOP AREA...AND THE WINTER STORM WATCH WILL BE
DISCONTINUED FOR THAT AREA.
WHERE THE BULK OF THE PRECIPITATION IS ALL SNOW NORTH AND WEST OF
THE KEVV/KPAH CORRIDOR...THERE IS HIGH CONFIDENCE IN A CRIPPLING
BLIZZARD. SNOWFALL AMOUNTS WITHIN THE DEFORMATION ZONE AXIS SHOULD
REACH A FOOT OR SO. LOOKING AT BUFKIT MOMENTUM TRANSFER...BOTH THE
NAM AND GFS INDICATE A HIGH POTENTIAL FOR GUSTS TO AT LEAST 35
KNOTS. THE SREF SHOWS A 50 PERCENT CHANCE OF SUSTAINED WINDS OVER 25
KNOTS IN SE MISSOURI. DESPITE THE HEAVY WET NATURE OF THE
SNOW...DRIFTS WILL BE MEASURED IN FEET IN THE SWATH OF HEAVIEST
SNOW. THE COMBINATION OF HEAVY WET SNOW AND WIND WILL LIKELY CAUSE
SOME POWER OUTAGES.
AS FOR THE TIMING OF THE EVENT...RADAR TRENDS AND HRRR GUIDANCE
INDICATE A LIGHT RAIN/SNOW MIX WILL SPREAD NORTHWARD INTO THE KPOF
AREA FROM 21Z TO 00Z. THE PRECIP WILL SPREAD NORTH ACROSS THE ENTIRE
FORECAST AREA IN THE 00Z TO 06Z TIMEFRAME. THE HEAVIEST PRECIP WILL
OCCUR ROUGHLY FROM 03Z TO 12Z. THE DEFORMATION ZONE WILL LIFT OUT
WEDNESDAY MORNING...BUT WINDS WILL NOT BEGIN TO DIMINISH UNTIL AT
LEAST 18Z. THE STRONG WINDS WILL CONTINUE TO RESULT IN EXTENSIVE
BLOWING AND DRIFTING IN THE HEAVY SNOW AREA.
&&
.SHORT TERM.../THROUGH WEDNESDAY NIGHT/...
ISSUED AT 411 AM CST TUE DEC 25 2012
THE MODELS HAVE SHIFTED FARTHER SOUTH WITH THE PATH OF THE WINTER
STORM SYSTEM CURRENTLY TAKING SHAPE OVER NORTHWEST TEXAS. IT WILL
MOVE TO THE ARKLATEX REGION BY 00Z WEDNESDAY AND SHIFT EAST
NORTHEAST THROUGH MIDDLE TENNESSEE WEDNESDAY MORNING. GIVEN THE SHIFT
TO THE SOUTH...THE ONSET OF PRECIPITATION MAY BE A BIT DELAYED TIL
00Z WED OR A BIT LATER. IN ADDITION...THE 00Z ECMWF AND NAM ARE LEADING
THE WAY IN HOLDING SIGNIFICANT SNOWS ACROSS MUCH OF THE AREA FROM
THE MISSISSIPPI RIVER COUNTIES OF SOUTHEAST MISSOURI EASTWARD
THROUGH THE REMAINDER OF THE AREA INTO WEDNESDAY MORNING. TRIED
TO PUSH THE GRIDS TOWARD THESE TRENDS.
LOW CLOUDS CURRENTLY COVER THE ENTIRE AREA...AND THE LAMP
GUIDANCE INDICATES THAT THEY WILL BE PERSISTENT THROUGH THE DAY
TODAY. THIS WILL LIKELY HOLD TEMPERATURES DOWN A FEW DEGREES FROM
PREVIOUS FORECAST LEVELS. THIS COULD LEAD TO A FREEZING RAIN
THREAT AT THE ONSET OF THE EVENT. BUT...A LOOK AT MODEL SOUNDINGS
INDICATES THAT THE WARM LAYER OVER MUCH OF THE AREA PRIOR TO THE
ONSET OF PRECIPITATION WILL NOT LIKELY SURVIVE THE SATURATION
PROCESS...AND SATURATION AND A CHANGE OVER TO SNOW SHOULD OUTPACE
THE FREEZING LINE EASTWARD ACROSS THE AREA. AREAS TO THE WEST OF
I-57 SHOULD BE ALL SNOW AFTER 00Z...AND THE FAR EASTERN PORTION OF
THE AREA WILL BECOME ALL SNOW AROUND 12Z WEDNESDAY.
USING HPC QPF AND A 12 TO 1 SNOW TO LIQUID RATIO WHEN AND WHERE
THERE IS PURE SNOW...AND A RATIO WELL UNDER 10 TO 1 WHERE THE
TRANSITION IS OCCURRING...NETTED A LARGE AREA OF 4 TO 10 INCH
STORM TOTAL SNOWFALL AMOUNTS. QPF IS LOWER OVER CARTER AND RIPLEY
COUNTIES...AND PORTIONS OF THOSE COUNTIES MAY STRUGGLE TO GET 4
INCHES...BUT IT WILL BE CLOSE ENOUGH. OVER CHRISTIAN...MUHLENBERG
AND TODD COUNTIES IT SPITS OUT ABOUT 4 INCHES...BUT CONFIDENCE IS
NOT AS HIGH IN THE TIMING OF THE CHANGE OVER. SO WARNING LEVEL
SNOWS ARE LIKELY ALL AREAS.
AM NOT OVERLY OPTIMISTIC ABOUT HITTING BLIZZARD WIND LEVELS OF 35
MPH...BUT SOME GUSTS TO THAT LEVEL WILL BE POSSIBLE. MEG AND LZK
HAVE DECIDED TO GO WITH A BLIZZARD WARNING...SO SEE NO REASON NOT
TO JOIN IN ON THAT PARTY. EVEN IF THE WINDS DO NOT QUITE GET
THERE...THE IMPACT WILL BE SUCH THAT THE BLIZZARD WARNING WILL BE
WARRANTED OVER MUCH OF THE AREA. WILL KEEP THE SAME TIMES AS FOR
THE WATCH...BUT IT MAY NEED TO BE EXTENDED INTO THE AFTERNOON
ACROSS THE EVANSVILLE TRI STATE AREA...ESPECIALLY IF BLOWING SNOW
DEVELOPS AS SUSPECTED.
WILL BE ISSUING THE WARNING FOR ALL BUT THE 3 SOUTHEASTERNMOST
COUNTIES. IT MAY BE NEEDED THERE...BUT AM CONCERNED BOTH ABOUT
SNOW AMOUNTS REACHING 4 INCHES...AND WINDS REACHING
CRITERIA WITH THE SURFACE LOW NOT FAR TO THE SOUTHEAST OF THAT
AREA. WILL ISSUE A WINTER STORM WATCH FOR THOSE 3 COUNTIES FROM
06Z-18Z WED...AND LET THE DAY SHIFT RE-CONSIDER IT LATER TODAY.
ANY ISSUES IN THOSE AREAS WILL HOLD OFF UNTIL THE VERY END OF THE
SECOND PERIOD.
DID NOT SEE MUCH EVIDENCE OF INSTABILITY TO SUPPORT THUNDER...SO
REMOVED THE THUNDER MENTION FROM THE FORECAST. HOWEVER...DO SEE
EVIDENCE OF POTENTIAL BANDING WITHIN THE DEFORMATION ZONE. THIS
COULD LEAD TO SOME LOCALLY VERY INTENSE SNOWFALL RATES AND
DEFINITE WHITE OUT CONDITIONS. DEFINITELY A FUN NIGHT IN STORE FOR
THE REGION.
.LONG TERM.../THURSDAY THROUGH MONDAY/...
ISSUED AT 411 AM CST TUE DEC 25 2012
NOT MUCH CHANGE IN THE EXTENDED. CONTINUED TO TREND COOLER WITH
TEMPS A FEW DEGREES BELOW ALLBLEND AND CLOSER TO THE ECMWF OUTPUT.
THIS WILL ALSO BE SUPPORTED BY THE SNOW COVER KEEPING THINGS A
LITTLE COOLER THAN MODELS WOULD INDICATE. SO ANY CHANGES TO TEMPS IN
THE FUTURE WOULD BE TO THE COLDER AND NOT WARMER. SIMILAR WITH DEW
POINTS AS WELL. WE HAVE NORTH THEN EAST WINDS AND INCREASE DEW
POINTS FROM THE MID TEENS TO THE MID 20S AND THATS DIFFICULT TO DO
WITH THE AFOREMENTIONED WIND DIRECTION. WE ARE STILL ON COURSE FOR
ANOTHER SNOW STORM FRIDAY NIGHT THAT LOOKS LIKE ANOTHER INCH
POSSIBLE WITH THIS SYSTEM. HOWEVER SOUTH OF THE OHIO RIVER THERE
COULD BE MIXING WITH RAIN THEN CHANGING OVER TO ALL RAIN SOUTH OF
THE RIVER BEFORE ENDING SATURDAY AFTN. HOWEVER IF THE SNOW FIELDS
COOL US A GOOD DEAL MORE THAN MODELS WOULD INDICATE THIS SECOND
STORM SYSTEM COULD BE ALL SNOW BUT STILL WOULD NOT PRODUCE MORE THAN
A COUPLE INCHES WITH CURRENT LIQUID EQUIVALENT AND RATIOS.
&&
.AVIATION...
ISSUED AT 1200 PM CST TUE DEC 25 2012
OR THE 18Z TAF ISSUANCE...PRIMARILY MOVE FROM VFR/MVFR VISIBILITIES
DUE TO CONTINUED MOISTENING OF BOUNDARY LAYER CANADIAN POLAR AIRMASS
ENGULFING THE TAF SITES. FOR THE PERIOD FROM 00Z TO 06Z...MOVE
QUICKLY TOWARD LOW MVFR TO LOWER IFR CATEGORY CEILINGS AS THE
WEATHER SYSTEM SHARPENS AND DEEPENS NEAR KCGI/KPAH TAF SITES. WITH
THE DEFORMATION ZONE NEARBY KCGI/KPAH...DECIDED TO GO WITH HIGH
SUSTAINED WINDS/WIND GUSTS...AS SURFACE WIND GRADIENT WILL BE
LOCALLY HIGHER. AS A CARRYOVER FROM THE 12Z TAFS...KEPT A TEMPORARY
MENTION OF LIFR/VLIFR CEILINGS AND VISIBILITIES...DURING THE MAXIMUM
STORM INTENSITY OVER THESE SITES. FOR THE KEVV AND KOWB TAF
SITES...GIVEN THE SHARP GRADIENT IN PRECIPITATION TYPE...KEPT THESE
LOCATIONS IN MVFR VISIBILITY RAIN THROUGH AT LEAST 09Z DECEMBER
26TH...THEN RAPIDLY CHANGE TO IFR/LIFR CONDITIONS THROUGH 13Z...WITH
A SLOW IMPROVEMENT TO IFR CONDITIONS THROUGH 18Z TUESDAY.
NOTE...A CORRECTION WAS SENT SHORTLY AFTER THE ROUTINE ISSUANCE TIME
TO REFLECT BLOWING SNOW DURING THE LOWEST CEILINGS AND VISIBILITIES.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
KY...BLIZZARD WARNING FROM 6 PM THIS EVENING TO NOON CST WEDNESDAY
FOR KYZ001>016-018>020.
WINTER STORM WATCH FROM LATE TONIGHT THROUGH WEDNESDAY MORNING
FOR KYZ017-021-022.
MO...BLIZZARD WARNING FROM 6 PM THIS EVENING TO NOON CST WEDNESDAY
FOR MOZ076-086-087-100-107>112-114.
IL...BLIZZARD WARNING FROM 6 PM THIS EVENING TO NOON CST WEDNESDAY
FOR ILZ075>078-080>094.
IN...BLIZZARD WARNING FROM 6 PM THIS EVENING TO NOON CST WEDNESDAY
FOR INZ081-082-085>088.
&&
$$
UPDATE...MY
SHORT TERM...DRS
LONG TERM....KH
AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
847 PM EST WED DEC 26 2012
.SYNOPSIS...
LIGHT SNOW WILL TAPER TO SCATTERED LIGHT SNOW SHOWERS AS LOW
PRESSURE EXITS NORTHEAST THURSDAY. HIGH PRESSURE WILL FOLLOW WITH
DRY CONDITIONS FRIDAY. A PASSING COLD FRONT WILL PROVIDE SHOWERS
OF RAIN AND SNOW THIS WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
FOR NOW WILL MAINTAIN WINTER WEATHER HEADLINES OVERNIGHT AS LIGHT
SNOW CONTINUES TO IMPACT TRAVEL CONDITIONS AND CLEAN UP.
BASED ON TRENDS IN RECENT SURFACE AND RADAR DATA...COUPLED WITH
RECENT RAP AND SREF MODEL OUTPUT...EXPECT LIGHT SNOW TO FURTHER
DECREASE IN INTENSITY OVERNIGHT. WITH RAP AND NAM MODEL PROFILES
SHOWING THE CLOUD TOPS DECREASING...AND SO CLOUD TOPS WARMING
ABOVE -10C...ITS POSSIBLE LIGHT FREEZING DRIZZLE CAN OCCUR LATE
TONIGHT.
SO HAVE FORECASTED MOST AREAS TO GET LESS THAN AN INCH OF
ADDITIONAL SNOW OVERNIGHT...WITH MAYBE 2 INCHES ACROSS THE I-80
CORRIDOR.
TEMPERATURES WILL DROP NO MORE THAN A COUPLE DEGREES OVERNIGHT.
SURFACE WINDS CAN GUST TO MAINLY 20-25 MPH...BUT THE WV-MD
MOUNTAINS CAN HAVE GUSTS AS HIGH AS 35-40 MPH TOWARD DAWN. HAVE
ADDED AREAS OF BLOWING SNOW THERE.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
POST SYSTEM NORTHWEST WINDS WILL MAINTAIN SCATTERED SNOW SHOWERS
ACROSS THE UPPER OHIO VALLEY...AND HIGH ENOUGH WIND GUSTS ACROSS
THE WV-MD MOUNTAINS FOR AREAS OF BLOWING SNOW.
FORECASTED A RESTRICTED TEMPERATURE CLIMB OF A COUPLE DEGREES FOR
HIGHS THURSDAY DUE TO THE CLOUDS AND SNOW COVER LIMITING DAYTIME
WARMING.
HIGH PRESSURE WILL FOLLOW WITH DRY AND SEASONABLY COLD CONDITIONS
THURSDAY NIGHT AND FRIDAY.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
A SHORT WAVE MOVING ACROSS THE OHIO VALLEY SATURDAY WILL BRING A
CHANCE OF SNOW. NORTHWEST FLOW BEHIND THE WAVE WILL BRING A CHANCE
OF LAKE EFFECT SNOW SHOWERS FOR SATURDAY NIGHT INTO SUNDAY. HIGH
PRESSURE WILL BRING DRY WEATHER FOR SUNDAY NIGHT AND MONDAY. ANOTHER
WAVE WILL BRING THE RISK OF SNOW FOR MONDAY NIGHT INTO TUESDAY.
NORTHWEST FLOW BEHIND THE SYSTEM WILL BRING A CHANCE OF SNOW SHOWERS
FOR TUESDAY NIGHT INTO WEDNESDAY.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
SOME TERMINALS HAVE HAD FLIGHT CATEGORIES RISE TO MVFR/VFR WITH DRY
SLOT MOVING THROUGH REGION...BUT EXPECT THAT ALL SITES WILL HAVE
CEILINGS EVENTUALLY DROP BACK DOWN TO IFR. AS INLAND LOW WEAKENS AND
COASTAL LOW BEGINS TO STRENGTHEN...THIS SHOULD ALLOW FOR SNOW TO
DIMINISH OVERNIGHT.
MAIN CONCERN BY MIDNIGHT IS THAT CLOUD TOPS MAY NOT BE COLD
ENOUGH TO SUPPORT ICE CRYSTALS...AND PRECIPITATION TYPE MAY
TRANSITION TO FREEZING DRIZZLE. WITH LOW CONFIDENCE...HAVE NOT PUT
FZDZ IN TAFS AT THIS TIME. CEILINGS WILL STRUGGLE TO REACH MVFR BY
LATE THURSDAY MORNING.
WINDS WILL BACK FROM NORTHEAST THIS EVENING TO NORTHWEST BY EARLY
THURSDAY MORNING. GUSTS WILL PICK UP DURING THE LATE MORNING AND
AFTERNOON HOURS...REACHING 20-25 KTS.
.OUTLOOK.../THURSDAY NIGHT THROUGH MONDAY/...
HIGH PRESSURE BUILDING IN FROM THE WEST SHOULD ALLOW CONDITIONS TO
LIFT TO VFR FOR THURSDAY NIGHT THROUGH FRIDAY. NEXT STORM SYSTEM
MOVING IN FRIDAY NIGHT COULD BRING SNOW SHOWERS AND RESTRICTIONS
THROUGH THE WEEKEND...WITH A RETURN TO VFR ON MONDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...WINTER STORM WARNING UNTIL 6 AM EST THURSDAY FOR MDZ001.
OH...WINTER STORM WARNING UNTIL 6 AM EST THURSDAY FOR OHZ039>041-
048>050-057>059-068.
WINTER WEATHER ADVISORY UNTIL 6 AM EST THURSDAY FOR OHZ069.
PA...WINTER STORM WARNING UNTIL 6 AM EST THURSDAY FOR PAZ007>009-
013>016-020>023-029-073>076.
WINTER WEATHER ADVISORY UNTIL 6 AM EST THURSDAY FOR PAZ031.
WV...WINTER STORM WARNING UNTIL 6 AM EST THURSDAY FOR WVZ001>003-
023-041.
WINTER WEATHER ADVISORY UNTIL 6 AM EST THURSDAY FOR WVZ004-012-
021-022.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
149 AM EST TUE DEC 25 2012
.SYNOPSIS...
LINGERING LIGHT DRIZZLE AND FREEZING DRIZZLE WILL GIVE WAY TO
PATCHY FOG OVERNIGHT AS LOW PRESSURE EXITS NORTHEAST. AFTER A DRY
BREAK CHRISTMAS DAY...A STRONG LOW PRESSURE SYSTEM WILL COME
NORTHEAST FROM TEXAS AND BRING POTENTIALLY HEAVY AMOUNTS OF SNOW
AND ICE TO THE UPPER OHIO VALLEY WEDNESDAY.
&&
.NEAR TERM /THROUGH TODAY/...
PER RECENT SURFACE AND RADAR DATA...HAVE CONTINUED TREND OF
DECREASING COVERAGE OF LIGHT DRIZZLE OVERNIGHT. MAINTAINED MENTION
OF LIGHT FREEZING DRIZZLE NEAR THE MOUNTAINS WHERE TEMPERATURES
HAVE SLIPPED BELOW 32. HAVE ALSO MAINTAINED MENTION OF PATCHY FOG.
WITH RUC AND NAM MODEL PROFILES SHOWING CLOUD TOPS DECREASING AND
HENCE CLOUD TOP TEMPERATURES WARMING TO WARMER THAN -10C...THE
FALLING PRECIPITATION WILL BE LIQUID DRIZZLE. IF BY CHANCE THERE
IS ANY SNOW IT WOULD BE LIKE FINE SNOW GRAINS. EITHER WAY IT WOULD
BE OF LITTLE CONSEQUENCE.
HAVE MAINTAINED THE FREEZING RAIN ADVISORY...BUT EXPECT TO
DISCONTINUE IT BY THE MIDNIGHT HOUR.
FORECASTED TEMPERATURES TO EITHER BE STEADY OVERNIGHT OR DROP BY
NO MORE THAN 2 DEGREES. EXPECT SOME TEMPERATURE CLIMB FOR DAYTIME
CHRISTMAS...BUT RECENT GFS LAMP AND NAM MOS AND SREF MODEL OUTPUT
HAVE TRENDED WITH COOLER HIGHS THAN EARLIER GUIDANCE. STILL THE
DAY SHOULD BE DRY AND DECENT FOR TRAVEL.
&&
.SHORT TERM /TONIGHT THROUGH THURSDAY/...
COMPACT BUT POTENT TROF THAT WILL BE YIELDING SVR WX IN THE DEEP
SOUTH WILL LIFT NEWD TUE NGT. COLD AIR WILL BE DRAWN SWD AS THE
ASSOCIATED WMFNT SHARPENS. WARM ADVCTN AT H8 WILL YIELD WDSPRD
PCPN BY WED MRNG.
FORCING FOR ASCENT WILL INCR DRAMATICALLY DURG THE DAY ON WED AS
DIFFLUENCE ALOFT STRENGTHENS AHEAD OF APRCHG UPR LOW. IT IS VERY
CLR THAT A LOT OF PCPN WILL OCCUR. THE PRIMARY FCST DIFFICULTY IS
IDENTIFYING THE NWD EXTENT OF THE H8 WARM TONGUE.
EXPECTATION IS THAT THERE WILL BE A SHARP GRADIENT FROM RAIN TO
FRZG RAIN TO SNOW ACRS FCST AREA. CONFIDENCE IS HIGH IN SNOW
MEETING WRNG CRITERION /IN EXCESS OF 6 IN PER 12 HR/ IN NRN PA
AND OH ZONES OWING TO VERY STRONG ASCENT IN DENDRITIC SNOW GROWTH
ZONE...SPCLY WED AFTN. DURG THIS TIME...SNOW RATES COULD BE QUITE
SGFNT IN I-80/I-79 CORRIDOR.
CONFIDENCE IS ALSO MDT THAT THERE WILL BE SGFNT ICE ACCUM IN MTN
ZONES...WHERE COLD AIR STAGNATES IN VLYS. ICE ACCUMS IN EXCESS OF
ONE-QUARTER INCH ARE PSBL.
FCST HAS LWR CONFIDENCE IN WHERE THE LINE BTWN RAIN AND FRZG RAIN
WILL ESTABLISH ITSELF. CLIMATOLOGY AND MODELS ALL SUGGEST THIS
LINE WILL BE NEAR AND SW FROM PITTSBURGH. ICE ACCUMS STILL XPCD IN
THESE LOCATIONS...BUT ATTM ARE XPCD TO RMN BLW WRNG THRESHOLD.
WINTER STORM WATCH HAS BEEN ISSUED FOR MUCH OF FCST AREA FROM
26/03Z TO 27/11Z. BY WED NGT...RGN WILL BE ON WRN SIDE OF THE
LOW...AND ANY PCPN WILL BE GENERATED/ENHANCED BY MODEST FLOW FROM
THE GRTLKS. ADDITIONAL ACCUMS PSBL WED NGT...BUT SHOULD BE LWR IN
MAGNITUDE THAN WED AFTN.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
HIPRES AND ASSOCIATED H5 RDG WILL MOVE ACRS FCST AREA ON FRI BUT
WILL BE TRANSIENT OWING TO APRCHG WAVES FROM NRN PLNS AND SRN
CONUS. WAVES ATTEMPT TO PHASE ON SAT/SUN...WITH ASSOCIATED PCPN
XPCD TO BE FOCUSED IN SRN ZONES. COLD AIR WILL BE SOLIDLY IN
PLACE...SO ANY PCPN WILL BE ASSOCIATED WITH SNOW.
ANOTHER WAVE XPCD TO GENERATE COASTAL LOPRES BY NEW YRS EVE.
DIFFERENCES IN AMPLITUDE OF THE UPR WAVE EXIST BTWN ECMWF AND GFS.
ATTM...ONLY LMTD IMPACT XPCD TO FCST AREA FROM THIS SYSTEM.
&&
.AVIATION /07Z TUESDAY THROUGH SATURDAY/...
DRIZZLE COVER HAS CONTINUED TO DECLINE INTO THE EARLY AM
HOURS...WITH NO SITE NOW REPORTING IT. OTERHWISE...LIFR STRATUS
CONTINUES ACROSS THE ENTIRE AREA...THOUGH SOME IMPROVEMENT IN
VISIBILITY HAS BEEN NOTED. STATISTICAL GUIDANCE SUGGESTS
VISIBILITIES SHOULD COME UP A BIT AS DEEPER SURFACE LAYER MOISTURE
STARTS TO EXIT THE AREA. ADDITIONALLY...AFTER SUNRISE...MODEL TIME
HEIGHT SECTIONS INDICATE SOME BREAKUP OF THE STRATUS. MOST SITES
SHOULD TREND TOWARD MVFR BY AFTERNOON WITH RATHER LIGHT WINDS
THROUGHOUT.
.OUTLOOK.../TUESDAY NIGHT THROUGH SATURDAY/...
MVFR RESTRICTIONS ARE EXPECTED TUESDAY NIGHT...WITH IFR RESTRICTIONS
LIKELY BY WEDNESDAY MORNING IN SN/+SN. SOME AREAS SOUTH OF KPIT
MAY MIX WITH OR CHANGE TO ZR/IP...HOWEVER BEHIND THE SNOW
BAND...DZ/FZDZ MAY BE THE PREDOMINANT WEATHER TYPE. DURATION OF
+SN SHOULD BE LONGEST FROM NORTH OF KZZV TO KPHD...KFKL...AND
KDUJ. FRIES
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...WINTER STORM WATCH FROM THIS EVENING THROUGH LATE WEDNESDAY
NIGHT FOR MDZ001.
OH...WINTER STORM WATCH FROM THIS EVENING THROUGH LATE WEDNESDAY
NIGHT FOR OHZ039>041-048>050-057>059.
PA...WINTER STORM WATCH FROM THIS EVENING THROUGH LATE WEDNESDAY
NIGHT FOR PAZ007>009-013>016-020>023-029-073-074-076.
WV...WINTER STORM WATCH FROM THIS EVENING THROUGH LATE WEDNESDAY
NIGHT FOR WVZ001>003-023-041.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
125 PM EST TUE DEC 25 2012
.UPDATE...
ISSUED AT 1100 AM EST TUE DEC 25 2012
INCREASED CLOUD COVER...AS MUCH OF THE CWA REMAINS UNDER A THICK
LAYER OF CLOUDS. THE ONLY SIGNIFICANT POCKETS OF CLEARING ARE OVER S
CENTRAL AND OVER FAR W LAKE SUPERIOR. ALSO INCREASED POPS N CENTRAL
GIVEN THE SLOWER THAN ANTICIPATED CLEARING AND RADAR ESTIMATED
SNOWFALL OF A QUARTER TO HALF AN INCH NEAR SAW OVER THE PAST HOUR.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 509 AM EST TUE DEC 25 2012
LATEST 09Z WV IMAGERY AND RUC ANALYSIS SHOWS A SHORTWAVE TROUGH
EXITING EAST OF THE UPPER GREAT LAKES. THIS SHORTWAVE LIKELY
PROVIDED SOME WEAK ENHANCEMENT TO LES BANDS OVER ALGER COUNTY
EARLIER THIS MORNING. LATEST MQT RADAR LOOP SHOWS AN ILL-DEFINED
DOMINANT LES BAND NEAR SHOT POINT BUT OTHERWISE RETURNS ON RADAR
WOULD JUST SUGGEST LITTLE MORE THAN FLURRIES ACROSS THE REST OF THE
NCNTRL FCST AREA.
LES SHOULD CONTINUE TO BE ON THE WANE THIS CHRISTMAS DAY AS FLOW
BCMS INCREASINGLY ANTICYCLONIC AND INCREASING SUBSIDENCE LOWERS
INVERSION HGTS TO BLO 4KFT. HAVE THIS WELL DEPICTED WITH DECREASING
TREND IN POP GRIDS THRU THE DAY. SNOWFALL INTENSITY/AMOUNTS WILL
REMAIN GREATEST OVER THE EAST WHERE AN ADDITIONAL INCH MAY
ACCUMULATE. MAY ALSO SEE AN ADDITIONAL INCH NEAR TWIN LAKES AREA IN
HOUGHTON COUNTY WHERE FOCUSED LOW-LVL CONVERGENCE COULD PROVIDE
LOCALIZED BOOST IN SNOW AMOUNTS.
LARGE SCALE ANTICYCLONIC FLOW...LOW INVERSION HGTS AOB 4KFT AND
INFLUX OF DRY AIR BLO INVERSION WILL ALL WORK TO KEEP LES AMOUNTS IN
CHECK TONIGHT. AGAIN THERE COULD BE SOME LOCALIZED ONE INCH
ACCUMULATIONS OVER ALGER AND NRN LUCE COUNTIES AND NEAR TWIN LAKES
IN HOUGHTON COUNTY WHERE DEVELOPING LAND BREEZES WILL AID LOW-LVL
CONVERGENCE. TAKING ALL FACTORS INTO CONSIDERATION...ONLY LOW CHC
POPS WILL BE JUSTIFIED.
TONIGHT SHOULD BE ONE OF THE COLDEST IN A WHILE...WITH A FEW
LOCATIONS OVER INTERIOR W PORTIONS OF UPPER MI FALLING BELOW ZERO
THANKS TO SHORTWAVE RDGG AND ASSOC INCREASING SUBSIDENCE/Q-VECT DIV
ALLOWING FOR LOW CLOUDS TO CLEAR OUT OVER INTERIOR LOCATIONS.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 509 AM EST TUE DEC 25 2012
NO BIG STORMS ARE ON THE HORIZON THROUGH THE END OF THE YEAR. WITH
85H TEMPS IN THE -10 TO -12 C RANGE...LIGHT NORTH NORTHEASTERLY
WINDS BETWEEN HIGH PRESSURE OVER ONTARIO AND SURFACE LOW MOVING UP
THE NORTHEAST COAST...AND INVERSION HEIGHTS GENERALLY AROUND
5KFT...EXPECT LIGHT LAKE EFFECT SNOW SHOWERS TO PERSIST NEAR LAKE
SUPERIOR THOUGH THURSDAY.
NORTHERN STREAM SHORTWAVE ENERGY WILL CARVE OUT AN UPPER TROUGH OVER
THE UPPER GREAT LAKES THIS WEEKEND. NET RESULT WILL BE A CHANCE FOR
SOME VERY LIGHT SYNOPTIC SNOW FRIDAY INTO SATURDAY AS SURFACE LOW
MOVES NORTH OF LAKES SUPERIOR. THEN...LOWERING 85H TEMPS WILL BRING
PERSISTENT LIGHT LAKE EFFECT SNOW SHOWERS TO NORTHWESTERLY WIND
FAVORED AREAS THROUGH THE END OF THE YEAR.
DAYTIME TEMPS WILL BE CLOSE TO NORMAL THROUGH THE END OF THE WEEK
BUT WITH PERSISTENT CLOUD COVER...ESPECIALLY NEAR LAKE SUPERIOR...
OVERNIGHT LOWS WILL CONTINUE TO RUN ABOVE NORMAL.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 124 PM EST TUE DEC 25 2012
PLENTY OF MOISTURE AND LIGHT WINDS AOB 5KTS UNDER A STRONG INVERSION
AROUND 4KFT LATE TONIGHT THROUGH WEDNESDAY MORNING COULD RESULT IN
LOWER VIS BR/SHSN CENTERED AROUND DAYBREAK AT CMX. HOWEVER...WILL
NOT JUMP ON THIS FCST QUITE YET...GIVEN THE LOW
PROBABILITY/PREDICTABILITY. MVFR CEILINGS AND OCCASIONAL VIS WILL BE
THE RULE FOR MUCH OF THE PERIOD THANKS TO THE LIKE NW FLOW OFF LAKE
SUPERIOR. SAW MAY BREAK OUT TO SCT BY THIS EVENING AS DRY AIR
CONTINUES TO WORK IN FROM S CENTRAL UPPER MI...WITH MVFR CEILINGS
RETURNING AGAIN BEFORE DAYBREAK. WINDS WILL BECOME LIGHT AND NNE
OVER W LAKE SUPERIOR BY WEDNESDAY MORNING...CUTTING OFF/ENDING MUCH
OF THE SNOW SHOWERS OVER CMX AND IWD...BUT WITH LOWERED CEILINGS/VIS
AND SAW THANKS TO UPSLOPE SNOW SHOWERS AND FLURRIES.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 509 AM EST TUE DEC 25 2012
A HIGH PRESSURE RIDGE CONTINUING TO BUILD IN FROM THE CANADIAN
PRAIRIES WILL PERSIST THROUGH MUCH OF THE WEEK...KEEPING WINDS AT OR
BELOW 25 KNOTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...KF
SHORT TERM...VOSS
LONG TERM...MZ
AVIATION...KF
MARINE...VOSS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1100 AM EST TUE DEC 25 2012
.UPDATE...
ISSUED AT 1100 AM EST TUE DEC 25 2012
INCREASED CLOUD COVER...AS MUCH OF THE CWA REMAINS UNDER A THICK
LAYER OF CLOUDS. THE ONLY SIGNIFICANT POCKETS OF CLEARING ARE OVER S
CENTRAL AND OVER FAR W LAKE SUPERIOR. ALSO INCREASED POPS N CENTRAL
GIVEN THE SLOWER THAN ANTICIPATED CLEARING AND RADAR ESTIMATED
SNOWFALL OF A QUARTER TO HALF AN INCH NEAR SAW OVER THE PAST HOUR.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 509 AM EST TUE DEC 25 2012
LATEST 09Z WV IMAGERY AND RUC ANALYSIS SHOWS A SHORTWAVE TROUGH
EXITING EAST OF THE UPPER GREAT LAKES. THIS SHORTWAVE LIKELY
PROVIDED SOME WEAK ENHANCEMENT TO LES BANDS OVER ALGER COUNTY
EARLIER THIS MORNING. LATEST MQT RADAR LOOP SHOWS AN ILL-DEFINED
DOMINANT LES BAND NEAR SHOT POINT BUT OTHERWISE RETURNS ON RADAR
WOULD JUST SUGGEST LITTLE MORE THAN FLURRIES ACROSS THE REST OF THE
NCNTRL FCST AREA.
LES SHOULD CONTINUE TO BE ON THE WANE THIS CHRISTMAS DAY AS FLOW
BCMS INCREASINGLY ANTICYCLONIC AND INCREASING SUBSIDENCE LOWERS
INVERSION HGTS TO BLO 4KFT. HAVE THIS WELL DEPICTED WITH DECREASING
TREND IN POP GRIDS THRU THE DAY. SNOWFALL INTENSITY/AMOUNTS WILL
REMAIN GREATEST OVER THE EAST WHERE AN ADDITIONAL INCH MAY
ACCUMULATE. MAY ALSO SEE AN ADDITIONAL INCH NEAR TWIN LAKES AREA IN
HOUGHTON COUNTY WHERE FOCUSED LOW-LVL CONVERGENCE COULD PROVIDE
LOCALIZED BOOST IN SNOW AMOUNTS.
LARGE SCALE ANTICYCLONIC FLOW...LOW INVERSION HGTS AOB 4KFT AND
INFLUX OF DRY AIR BLO INVERSION WILL ALL WORK TO KEEP LES AMOUNTS IN
CHECK TONIGHT. AGAIN THERE COULD BE SOME LOCALIZED ONE INCH
ACCUMULATIONS OVER ALGER AND NRN LUCE COUNTIES AND NEAR TWIN LAKES
IN HOUGHTON COUNTY WHERE DEVELOPING LAND BREEZES WILL AID LOW-LVL
CONVERGENCE. TAKING ALL FACTORS INTO CONSIDERATION...ONLY LOW CHC
POPS WILL BE JUSTIFIED.
TONIGHT SHOULD BE ONE OF THE COLDEST IN A WHILE...WITH A FEW
LOCATIONS OVER INTERIOR W PORTIONS OF UPPER MI FALLING BELOW ZERO
THANKS TO SHORTWAVE RDGG AND ASSOC INCREASING SUBSIDENCE/Q-VECT DIV
ALLOWING FOR LOW CLOUDS TO CLEAR OUT OVER INTERIOR LOCATIONS.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 509 AM EST TUE DEC 25 2012
NO BIG STORMS ARE ON THE HORIZON THROUGH THE END OF THE YEAR. WITH
85H TEMPS IN THE -10 TO -12 C RANGE...LIGHT NORTH NORTHEASTERLY
WINDS BETWEEN HIGH PRESSURE OVER ONTARIO AND SURFACE LOW MOVING UP
THE NORTHEAST COAST...AND INVERSION HEIGHTS GENERALLY AROUND
5KFT...EXPECT LIGHT LAKE EFFECT SNOW SHOWERS TO PERSIST NEAR LAKE
SUPERIOR THOUGH THURSDAY.
NORTHERN STREAM SHORTWAVE ENERGY WILL CARVE OUT AN UPPER TROUGH OVER
THE UPPER GREAT LAKES THIS WEEKEND. NET RESULT WILL BE A CHANCE FOR
SOME VERY LIGHT SYNOPTIC SNOW FRIDAY INTO SATURDAY AS SURFACE LOW
MOVES NORTH OF LAKES SUPERIOR. THEN...LOWERING 85H TEMPS WILL BRING
PERSISTENT LIGHT LAKE EFFECT SNOW SHOWERS TO NORTHWESTERLY WIND
FAVORED AREAS THROUGH THE END OF THE YEAR.
DAYTIME TEMPS WILL BE CLOSE TO NORMAL THROUGH THE END OF THE WEEK
BUT WITH PERSISTENT CLOUD COVER...ESPECIALLY NEAR LAKE SUPERIOR...
OVERNIGHT LOWS WILL CONTINUE TO RUN ABOVE NORMAL.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 635 AM EST TUE DEC 25 2012
WRLY FLOW AT KIWD AND KCMX WILL MAINTAIN IFR CIGS/FLURRIES INTO LATE
MORNING AND MVFR CIGS THEREAFTER INTO TONIGHT. NW FLOW SHIFTING TO
WNW LATE THIS AFTERNOON AT KSAW WILL ALLOW MVFR CIGS/FLURRIES TO
DISSIPATE AS VFR CONDITIONS TAKE HOLD UNTIL LATE TONIGHT. AS WINDS
VEER NNW LATE TONIGHT...LOOK FOR MVFR LAKE CLOUDS/FLURRIES TO MOVE
BACK IN AGAIN.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 509 AM EST TUE DEC 25 2012
A HIGH PRESSURE RIDGE CONTINUING TO BUILD IN FROM THE CANADIAN
PRAIRIES WILL PERSIST THROUGH MUCH OF THE WEEK...KEEPING WINDS AT OR
BELOW 25 KNOTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...KF
SHORT TERM...VOSS
LONG TERM...MZ
AVIATION...VOSS
MARINE...VOSS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
636 AM EST TUE DEC 25 2012
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 509 AM EST TUE DEC 25 2012
LATEST 09Z WV IMAGERY AND RUC ANALYSIS SHOWS A SHORTWAVE TROUGH
EXITING EAST OF THE UPPER GREAT LAKES. THIS SHORTWAVE LIKELY
PROVIDED SOME WEAK ENHANCEMENT TO LES BANDS OVER ALGER COUNTY
EARLIER THIS MORNING. LATEST MQT RADAR LOOP SHOWS AN ILL-DEFINED
DOMINANT LES BAND NEAR SHOT POINT BUT OTHERWISE RETURNS ON RADAR
WOULD JUST SUGGEST LITTLE MORE THAN FLURRIES ACROSS THE REST OF THE
NCNTRL FCST AREA.
LES SHOULD CONTINUE TO BE ON THE WANE THIS CHRISTMAS DAY AS FLOW
BCMS INCREASINGLY ANTICYCLONIC AND INCREASING SUBSIDENCE LOWERS
INVERSION HGTS TO BLO 4KFT. HAVE THIS WELL DEPICTED WITH DECREASING
TREND IN POP GRIDS THRU THE DAY. SNOWFALL INTENSITY/AMOUNTS WILL
REMAIN GREATEST OVER THE EAST WHERE AN ADDITIONAL INCH MAY
ACCUMULATE. MAY ALSO SEE AN ADDITIONAL INCH NEAR TWIN LAKES AREA IN
HOUGHTON COUNTY WHERE FOCUSED LOW-LVL CONVERGENCE COULD PROVIDE
LOCALIZED BOOST IN SNOW AMOUNTS.
LARGE SCALE ANTICYCLONIC FLOW...LOW INVERSION HGTS AOB 4KFT AND
INFLUX OF DRY AIR BLO INVERSION WILL ALL WORK TO KEEP LES AMOUNTS IN
CHECK TONIGHT. AGAIN THERE COULD BE SOME LOCALIZED ONE INCH
ACCUMULATIONS OVER ALGER AND NRN LUCE COUNTIES AND NEAR TWIN LAKES
IN HOUGHTON COUNTY WHERE DEVELOPING LAND BREEZES WILL AID LOW-LVL
CONVERGENCE. TAKING ALL FACTORS INTO CONSIDERATION...ONLY LOW CHC
POPS WILL BE JUSTIFIED.
TONIGHT SHOULD BE ONE OF THE COLDEST IN A WHILE...WITH A FEW
LOCATIONS OVER INTERIOR W PORTIONS OF UPPER MI FALLING BELOW ZERO
THANKS TO SHORTWAVE RDGG AND ASSOC INCREASING SUBSIDENCE/Q-VECT DIV
ALLOWING FOR LOW CLOUDS TO CLEAR OUT OVER INTERIOR LOCATIONS.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 509 AM EST TUE DEC 25 2012
NO BIG STORMS ARE ON THE HORIZON THROUGH THE END OF THE YEAR. WITH
85H TEMPS IN THE -10 TO -12 C RANGE...LIGHT NORTH NORTHEASTERLY
WINDS BETWEEN HIGH PRESSURE OVER ONTARIO AND SURFACE LOW MOVING UP
THE NORTHEAST COAST...AND INVERSION HEIGHTS GENERALLY AROUND
5KFT...EXPECT LIGHT LAKE EFFECT SNOW SHOWERS TO PERSIST NEAR LAKE
SUPERIOR THOUGH THURSDAY.
NORTHERN STREAM SHORTWAVE ENERGY WILL CARVE OUT AN UPPER TROUGH OVER
THE UPPER GREAT LAKES THIS WEEKEND. NET RESULT WILL BE A CHANCE FOR
SOME VERY LIGHT SYNOPTIC SNOW FRIDAY INTO SATURDAY AS SURFACE LOW
MOVES NORTH OF LAKES SUPERIOR. THEN...LOWERING 85H TEMPS WILL BRING
PERSISTENT LIGHT LAKE EFFECT SNOW SHOWERS TO NORTHWESTERLY WIND
FAVORED AREAS THROUGH THE END OF THE YEAR.
DAYTIME TEMPS WILL BE CLOSE TO NORMAL THROUGH THE END OF THE WEEK
BUT WITH PERSISTENT CLOUD COVER...ESPECIALLY NEAR LAKE SUPERIOR...
OVERNIGHT LOWS WILL CONTINUE TO RUN ABOVE NORMAL.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 635 AM EST TUE DEC 25 2012
WRLY FLOW AT KIWD AND KCMX WILL MAINTAIN IFR CIGS/FLURRIES INTO LATE
MORNING AND MVFR CIGS THEREAFTER INTO TONIGHT. NW FLOW SHIFTING TO
WNW LATE THIS AFTERNOON AT KSAW WILL ALLOW MVFR CIGS/FLURRIES TO
DISSIPATE AS VFR CONDITIONS TAKE HOLD UNTIL LATE TONIGHT. AS WINDS
VEER NNW LATE TONIGHT...LOOK FOR MVFR LAKE CLOUDS/FLURRIES TO MOVE
BACK IN AGAIN.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 509 AM EST TUE DEC 25 2012
A HIGH PRESSURE RIDGE CONTINUING TO BUILD IN FROM THE CANADIAN
PRAIRIES WILL PERSIST THROUGH MUCH OF THE WEEK...KEEPING WINDS AT OR
BELOW 25 KNOTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...VOSS
LONG TERM...MZ
AVIATION...VOSS
MARINE...VOSS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
510 AM EST TUE DEC 25 2012
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 509 AM EST TUE DEC 25 2012
LATEST 09Z WV IMAGERY AND RUC ANALYSIS SHOWS A SHORTWAVE TROUGH
EXITING EAST OF THE UPPER GREAT LAKES. THIS SHORTWAVE LIKELY
PROVIDED SOME WEAK ENHANCEMENT TO LES BANDS OVER ALGER COUNTY
EARLIER THIS MORNING. LATEST MQT RADAR LOOP SHOWS AN ILL-DEFINED
DOMINANT LES BAND NEAR SHOT POINT BUT OTHERWISE RETURNS ON RADAR
WOULD JUST SUGGEST LITTLE MORE THAN FLURRIES ACROSS THE REST OF THE
NCNTRL FCST AREA.
LES SHOULD CONTINUE TO BE ON THE WANE THIS CHRISTMAS DAY AS FLOW
BCMS INCREASINGLY ANTICYCLONIC AND INCREASING SUBSIDENCE LOWERS
INVERSION HGTS TO BLO 4KFT. HAVE THIS WELL DEPICTED WITH DECREASING
TREND IN POP GRIDS THRU THE DAY. SNOWFALL INTENSITY/AMOUNTS WILL
REMAIN GREATEST OVER THE EAST WHERE AN ADDITIONAL INCH MAY
ACCUMULATE. MAY ALSO SEE AN ADDITIONAL INCH NEAR TWIN LAKES AREA IN
HOUGHTON COUNTY WHERE FOCUSED LOW-LVL CONVERGENCE COULD PROVIDE
LOCALIZED BOOST IN SNOW AMOUNTS.
LARGE SCALE ANTICYCLONIC FLOW...LOW INVERSION HGTS AOB 4KFT AND
INFLUX OF DRY AIR BLO INVERSION WILL ALL WORK TO KEEP LES AMOUNTS IN
CHECK TONIGHT. AGAIN THERE COULD BE SOME LOCALIZED ONE INCH
ACCUMULATIONS OVER ALGER AND NRN LUCE COUNTIES AND NEAR TWIN LAKES
IN HOUGHTON COUNTY WHERE DEVELOPING LAND BREEZES WILL AID LOW-LVL
CONVERGENCE. TAKING ALL FACTORS INTO CONSIDERATION...ONLY LOW CHC
POPS WILL BE JUSTIFIED.
TONIGHT SHOULD BE ONE OF THE COLDEST IN A WHILE...WITH A FEW
LOCATIONS OVER INTERIOR W PORTIONS OF UPPER MI FALLING BELOW ZERO
THANKS TO SHORTWAVE RDGG AND ASSOC INCREASING SUBSIDENCE/Q-VECT DIV
ALLOWING FOR LOW CLOUDS TO CLEAR OUT OVER INTERIOR LOCATIONS.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 509 AM EST TUE DEC 25 2012
NO BIG STORMS ARE ON THE HORIZON THROUGH THE END OF THE YEAR. WITH
85H TEMPS IN THE -10 TO -12 C RANGE...LIGHT NORTH NORTHEASTERLY
WINDS BETWEEN HIGH PRESSURE OVER ONTARIO AND SURFACE LOW MOVING UP
THE NORTHEAST COAST...AND INVERSION HEIGHTS GENERALLY AROUND
5KFT...EXPECT LIGHT LAKE EFFECT SNOW SHOWERS TO PERSIST NEAR LAKE
SUPERIOR THOUGH THURSDAY.
NORTHERN STREAM SHORTWAVE ENERGY WILL CARVE OUT AN UPPER TROUGH OVER
THE UPPER GREAT LAKES THIS WEEKEND. NET RESULT WILL BE A CHANCE FOR
SOME VERY LIGHT SYNOPTIC SNOW FRIDAY INTO SATURDAY AS SURFACE LOW
MOVES NORTH OF LAKES SUPERIOR. THEN...LOWERING 85H TEMPS WILL BRING
PERSISTENT LIGHT LAKE EFFECT SNOW SHOWERS TO NORTHWESTERLY WIND
FAVORED AREAS THROUGH THE END OF THE YEAR.
DAYTIME TEMPS WILL BE CLOSE TO NORMAL THROUGH THE END OF THE WEEK
BUT WITH PERSISTENT CLOUD COVER...ESPECIALLY NEAR LAKE SUPERIOR...
OVERNIGHT LOWS WILL CONTINUE TO RUN ABOVE NORMAL.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1241 AM EST TUE DEC 25 2012
WITH A STRONG INVERSION OVER THE AREA...THE STRATUS CLOUDS WILL
PERSIST THROUGH THE FORECAST PERIOD EXCEPT AT IWD WHERE A DEVELOPING
SW WIND WILL PUSH THE LAKE EFFECT CLOUDS NORTH OF THEM ON TUE
AFTERNOON. OTHERWISE...A NW FLOW WILL BRING SOME OCCASIONAL LIGHT
LAKE EFFECT SNOW TO THE TAF SITES BUT VSBYS SHOULD NOT BE RESTRICTED
BY IT. SO...EXPECT MVFR CIGS AT BOTH KCMX AND KSAW THROUGH THE FCST
PERIOD.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 509 AM EST TUE DEC 25 2012
A HIGH PRESSURE RIDGE CONTINUING TO BUILD IN FROM THE CANADIAN
PRAIRIES WILL PERSIST THROUGH MUCH OF THE WEEK...KEEPING WINDS AT OR
BELOW 25 KNOTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...VOSS
LONG TERM...MZ
AVIATION...07
MARINE...VOSS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1242 AM EST TUE DEC 25 2012
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 434 PM EST MON DEC 24 2012
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL LOW OVER NRN
ONTARIO WITH A TROUGH EXTENDING INTO THE WESTERN GREAT LAKES. A
SHORTWAVE TROUGH WAS LOCATED OVER LOWER MI WHILE UPSTREAM A WEAKER
SHRTWV EXTENDED FROM THE SRN END OF JAMES BAY TO NEAR KINL. ALTHOUGH THE
STRONGEST 700-300 MB QVECTOR CONV REMAINED SOUTHEAST OF UPPER MI
WHILE...SOME WEAK TO MODERATE FORCING LINGERING OVER THE AREA
SUPPORTED AREAS OF LIGHT SNOW WITH VISIBILITIES GENERALLY AT OR
ABOVE 5SM. NW LOW LEVEL WINDS WITH 850 MB TEMPS AROUND -15C ALSO
SUPPORTED SOME LIGHT LES BANDS. A SIGNIFICANT LIMITING FACTOR FOR
LES INTENSITY WAS LOW INVERSION HEIGHTS AROUND 4K FT AND INFLUX OF
DRIER AIR BELOW THE INVERSION.
TONIGHT...INCREASING LOW-LVL CONVERGENCE AIDED BY DEVELOPING LAND
BREEZES SHOULD PROVIDE ADDITIONAL FOCUS FOR LES INTO ERN ALGER/NRN
SCHOOLCRAFT AND PERHAPS OVER THE PORCUPINE MOUNTAINS OVER THE WEST.
THE DRY AIR UPSTREAM AND LOW INVERSION HEIGHTS WILL LIMIT
AMOUNTS...ESPECIALLY OVER THE WEST...TO GENERALLY AN INCH OR LESS.
GREATER POPS WERE INCLUDED OVER THE ERN CWA WHERE THE LONGER FETCH
WILL HELP KEEP INVERSION HEIGHTS IN THE 5K-7K FT RANGE AND CLOUD
SUPPORT SLIGHTLY GREATER SNOWFALL AMOUNTS OF AN INCH OR TWO.
LES WILL CONTINUE INTO CHRISTMAS DAY AS 850 MB TEMPS REMAIN NEAR
-14C BUT SHOULD DIMINISH AS WINDS BACK TO WNW WITH SLOWLY LOWERING
INVERSION HEIGHTS AND MORE ANTICYCLONIC/DIVERGENT LOW LEVEL FLOW.
SNOWFALL INTENSITY/AMOUNTS WILL REMAIN GREATEST OVER THE EAST WHERE
AN ADDITIONAL INCH MAY ACCUMULATE.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 434 PM EST MON DEC 24 2012
NOT A LOT OF EXCITING WEATHER TO GO IN DEPTH ABOUT FOR THE LONG TERM
PERIOD /TUESDAY NIGHT THROUGH NEXT MONDAY/. WE WILL BE DOMINATED BY
NORTHERLY WINDS FOR MUCH OF THE PERIOD WITH SLIGHT TO LOW CHANCE
POPS NEAR LAKE SUPERIOR...AS THE STORM TRACK CONTINUES TO BE WELL TO
OUR S.
TUESDAY NIGHT SHOULD BE ONE OF THE COLDEST IN A WHILE...WITH A FEW
LOCATIONS OVER INTERIOR W PORTIONS OF UPPER MI FALLING BELOW 0
THANKS TO A POCKET OF CLEARING NOTED BY SOME OF THE SMALLER SCALE
MODELS.
DID INCREASE THE FCST MODEL CONSENSUS POPS FOR SATURDAY NIGHT
THROUGH MONDAY...HEDGING THE FCST CLOSER TO THE ECMWF AND SLIGHTLY
HIGHER CONFIDENCE IN COLD AIR ROTATING IN ON MAINLY NW WINDS. THE
OUTLIER WAS THE GFS...PARTICULARLY FROM SUNDAY ON AS IT BROUGHT A
SFC LOW FROM CENTRAL CANADA TO ONTARIO SUNDAY NIGHT. A WEAKENING SFC
TROUGH CONTINUED FOR THE GFS...EXTENDING W FROM THE EXITING LOW OFF
THE COAST OF MAINE. THE ECMWF HAD FAIRLY STEADY 850MB TEMPS OF -15
TO -20C FROM SATURDAY NIGHT THROUGH MONDAY...WITH AT LEAST LIMITED
MOISTURE TO BRING IN A GOOD CHANCE OF SNOW SHOWERS.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1241 AM EST TUE DEC 25 2012
WITH A STRONG INVERSION OVER THE AREA...THE STRATUS CLOUDS WILL
PERSIST THROUGH THE FORECAST PERIOD EXCEPT AT IWD WHERE A DEVELOPING
SW WIND WILL PUSH THE LAKE EFFECT CLOUDS NORTH OF THEM ON TUE
AFTERNOON. OTHERWISE...A NW FLOW WILL BRING SOME OCCASIONAL LIGHT
LAKE EFFECT SNOW TO THE TAF SITES BUT VSBYS SHOULD NOT BE RESTRICTED
BY IT. SO...EXPECT MVFR CIGS AT BOTH KCMX AND KSAW THROUGH THE FCST
PERIOD. &&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 434 PM EST MON DEC 24 2012
A HIGH PRESSURE RIDGE BUILDING IN FROM THE CANADIAN PRAIRIES TODAY
AND TONIGHT WILL LINGER THROUGH MUCH OF THE WEEK...KEEPING WINDS
AT OR BELOW 25 KNOTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...KF
AVIATION...07
MARINE...JLB
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
1143 PM EST MON DEC 24 2012
.AVIATION...
//DISCUSSION...
SNOW AND LOW STRATUS HAVE PULLED OUT FOR THE MOST PART OVER THE TAF
SITES. ALTHOUGH THERE IS ADDITIONAL STRATUS UPSTREAM...OBSERVATIONS
DO NOT SHOW THIS STRATUS MAKING A BEELINE FOR THE TAF SITES
OVERNIGHT. AT THIS POINT WILL KEEP CIGS VFR WITH A TEMPO GROUP EARLY
ON FOR LINGERING STRATUS. THERE ARE SOME BREAKS IN THE CLOUDS
UPSTREAM...HOWEVER WITH A CONTINUED FEED OF MOISTURE OFF THE GREAT
LAKES THERE IS NOT ENOUGH CONFIDENCE TO CLEAR THE CLOUDS OUT AT THIS
POINT. A PERIOD OF QUIET WEATHER IS EXPECTED FOR THE REST OF TUESDAY
AS DAYTIME SNOW SHOWERS STAY TO THE EAST OF THE TAF SITES WITH
MOISTURE COMING IN OFF LAKE HURON.
//DTW THRESHOLD THREATS...
* MEDIUM CONFIDENCE IN CEILINGS BELOW 5000 FT THROUGH THE TAF
PERIOD.
&&
.PREV DISCUSSION...ISSUED 947 PM EST MON DEC 24 2012
UPDATE...
SNOW IS QUICKLY COMING TO AN END ACROSS SOUTHEAST MICHIGAN AS THE
LAST OF THE SNOW SHOWERS IS FALLING ACROSS THE EASTERN THUMB AHEAD
OF A SHORTWAVE PUSHING THROUGH SOUTHERN LOWER MICHIGAN. WHILE MANY
LOCATIONS SAW THE ADVERTISED 0.5 TO 1 INCH OF
SNOWFALL...SEVERAL LOCATIONS GOT CLOSER TO 2 INCHES IN A SWATH
FROM LIVINGSTON TO MACOMB COUNTY. THESE AREAS WERE IN AN AREA OF
ENHANCED CONVECTION EMBEDDED IN THE MAIN SNOW BANDS WHICH PROVIDED
A QUICK BURST OF SNOWFALL AND WITH IT SLIGHTLY HIGHER TOTALS IN
THIS CORRIDOR.
THE REST OF THE NIGHT LOOKS TO BE QUIET WITH ONLY A FEW LINGERING
FLURRIES AS THE FORCING TRACKS EAST OF THE AREA. THIS RECENT ROUND
OF SNOW SHOULD OFFICIALLY BRING A WHITE CHRISTMAS TO MOST OF
SOUTHEAST MICHIGAN TOMORROW WITH THE OFFICIAL YARDSTICK FOR THIS
BEING AN INCH OF SNOW ON THE GROUND AT 7 AM.
PREV DISCUSSION...ISSUED 337 PM EST MON DEC 24 2012
SHORT TERM...THIS EVENING AND TONIGHT
UPSTREAM LIGHT SNOW AND VIRGA HAVE BEEN STEADILY PUSHING INTO THE
AREA AHEAD OF THE COMPACT MID-LEVEL SHORTWAVE ROTATING ACROSS THE
LOWER PENINSULA THIS AFTERNOON. FOR SEVERAL HOURS NOW, A PERIOD OF
VIRGA HAS PRECEDED A RATHER BRIEF PERIOD OF LIGHT TO MODERATE
SNOWFALL.
ANALYSIS OF OBSERVATIONS AND SHORT TERM MODEL DATA INDICATE THAT THE
ONGOING SNOWFALL/VIRGA IS STRONGLY TIED TO TWO SEPARATE FEATURES.
THE FIRST, AND PRIMARY TO AFFECT SOUTHEAST MICHIGAN, IS THE BROAD
CORRIDOR OF ASCENT ASSOCIATED WITH DCVA PRECEDING THE WAVE ITSELF.
THE SECOND, MAINLY AFFECTING LOCATIONS SOUTH OF THE BORDER...PERHAPS
AS FAR NORTH AS THE I-94 CORRIDOR...IS A DEEP FRONTOLYTIC
CIRCULATION LEADING THE NOSE OF THE ASSOCIATED 80-KT JET STREAK.
THIS REGION OF FORCED COLD ASCENT HAS ALSO DRAWN UPON A POCKET OF WEAK
MID-LEVEL INSTABILITY TO PRODUCE A STRONGER CONVECTIVE RESPONSE TO
THE SOUTH AND OCCASIONAL ECHOES OF 40DBZ OVER NORTHERN IN.
THE NORTHWARD MIGRATION OF THE ELEVATED FRONTAL ZONE/THETA-E RIDGE
AS WELL AS SUB-850 EASTERLY MOISTURE ADVECTION WILL HELP TO ERODE
THE H85-H7 DRY LAYER APPARENT ON THIS MORNING`S 12Z DTX SOUNDING AND
ALLOW FOR A SUBSEQUENT EXPANSION OF LIGHT SNOW AND DECREASE IN VIRGA
OVER THE NEXT FEW HOURS. RECENT RADAR TRENDS CONFIRM THESE
EXPECTATIONS (AND YESTERDAY`S NMM CORE SOLUTIONS). RUC ANALYSIS
SUGGESTS THAT WHILE A BRIEF PERIOD OF CONVECTIVE PRECIP WILL BE
POSSIBLE ACROSS THE SOUTHERN CWA, THE BULK OF THE EVENT WILL LIKELY
TAKE PLACE ACROSS THE HEART OF THE FORECAST AREA AND WILL BE
CHARACTERIZED BY A FEW HOURS OF LIGHT SNOW WITH EMBEDDED MODERATE
BANDING OWING TO BOTH A VERY WEAKLY STATICALLY STABLE ATMOSPHERE
ABOVE THE LOW-LEVEL FRONT AND MARGINAL MID-LEVEL INSTABILITY. THE
FORECAST HAS THEREFORE BEEN AMENDED TO REFLECT A HIGHER POP SCENARIO
FROM APPROXIMATELY LIVINGSTON TO TO LAPEER COUNTIES WHERE A
WIDESPREAD HALF INCH OR SO IS STILL POSSIBLE. LOCATIONS AFFECTED BY
SAID BANDING WILL SEE A PORTION OF THE SNOW ACCUMULATE MORE QUICKLY
AS VSBYS FALL TO 1-2 MILES PER UPSTREAM OBS...RESULTING IN THE
POTENTIAL FOR A FEW ISOLATED 1" ACCUMS.
LONG TERM...
CHRISTMAS DAY WILL BE ON THE TRANQUIL SIDE OVERALL AROUND SE
MICHIGAN LEADING INTO AN ACTIVE PERIOD OF WINTER WEATHER AFTER THE
HOLIDAY. HIGHER END ADVISORY CRITERIA SNOWFALL AMOUNTS AND RATES ARE
ANTICIPATED FOR SE MICHIGAN WEDNESDAY THROUGH WEDNESDAY NIGHT WITH
THE TIMING ON THE DAY AFTER CHRISTMAS AND POTENTIAL TRAVEL IMPACTS
BEING THE NOTABLE ASPECT OF THE EVENT.
THE WEDNESDAY LOW PRESSURE SYSTEM WILL BE PRECEDED BY SOME LAKE
EFFECT SNOW SHOWERS MAKING INLAND PROGRESS OFF LAKE HURON DURING
CHRISTMAS DAY. INLAND PROGRESS COULD BE AS FAR SOUTH AS I-69 AND
WEST TO I-75 ON A SCATTERED BASIS WITH GREATER COVERAGE IN THE THUMB
CLOSER TO THE LAKE. INSTABILITY WILL BE MODEST WITH LAKE TO 850
DELTA-T RUNNING AROUND 15C BUT WITH INVERSION HEIGHT BOOSTED BY SOME
SEEDING FROM MID LEVEL MOISTURE TRAILING TODAY`S WAVE. THE BROAD
INVERTED SURFACE TROUGH WILL PROVIDE A FAVORABLE LOW LEVEL WIND
FIELD FOR FOCUSING NORTHERLY FLOW INTO THE THUMB FOR A FEW HOURS
BEFORE FILLING AND DRYING TOWARD EVENING.
THE MAIN CONCERN IN THE FORECAST REMAINS THE EVOLUTION OF A LARGE
LOW PRESSURE SYSTEM SET TO IMPACT MUCH OF THE COUNTRY EAST OF THE
MISSISSIPPI WEDNESDAY INTO THURSDAY. THIS SYSTEM IS EXPECTED TO
NEGATIVELY IMPACT POST HOLIDAY TRAVEL ACROSS THE REGION WITH
MODERATE SNOW ACCUMULATION REMAINING THE PRIMARY EXPECTATION IN SE
MICHIGAN. SUBJECT UPPER LEVEL ENERGY WAS MORE FULLY INLAND FROM THE
WEST COAST FOR THE MORNING UPPER AIR ANALYSIS, SO IT IS A GOOD SIGN
THAT THE 12Z MODEL CYCLE HAS NOT SHIFTED MUCH OFF OF EARLIER
SOLUTIONS AS THE SYSTEM DEVELOPS OVER THE WESTERN GULF COAST DURING
CHRISTMAS DAY AND DEEPENS INTO THE TENNESSEE VALLEY BY WEDNESDAY
MORNING. AGREEMENT BETWEEN THE NAM, GFS, ECMWF, AND LOCAL WRF GLOBAL
IS EXCELLENT BY THEN ON THE POSITION AND INTENSITY OF THE LARGE
SCALE FEATURES ASSOCIATED WITH THE SYSTEM. THE CANADIAN REMAINS
FASTER/FARTHER EAST IN THE SOLUTION SPACE PERHAPS REPRESENTING THE
STRONG INFLUENCE ON TRACK AND STRENGTH BY THE SOUTHWARD POSITION OF
THE UPPER JET AXIS FROM SOUTHERN CALIFORNIA TO THE CENTRAL GULF
COAST. THERE IS ALSO CONSIDERABLE LOW LEVEL BAROCLINICITY, GULF
MOISTURE, AND WARM SECTOR INSTABILITY IN ADVANCE OF THE WAVE FROM
THE TENNESSEE VALLEY TO THE MID ATLANTIC STATES. ALL OF THIS, ALONG
WITH A NEW ROUND OF UPPER LEVEL HEIGHT FALLS OVER THE WEST COAST,
FAVORS PROGRESSION AND THE TRANSFER OF CYCLOGENESIS TO THE EAST
COAST DURING WEDNESDAY.
CONFIDENCE IN THE MODEL SOLUTIONS ON THE BULK FEATURES DOES NOT GET
US OUT OF THE WOODS ON A WINTER EVENT OR SIMPLIFY THE FORECAST FOR
OUR AREA DURING WEDNESDAY INTO WEDNESDAY NIGHT AS A CONSIDERABLE
AMOUNT OF MOISTURE REMAINS ADVERTISED FOR THE REGION. WITH AN EASY
CALL ON ALL SNOW AS THE PRECIPITATION TYPE, THE QUESTION OF AMOUNT
REMAINS TIED TO THE CHARACTER AND DURATION OF MAX FORCING AND
MICROPHYSICAL ASPECTS OF THE SNOW OVER SE MICHIGAN DURING THE PEAK
OF THE EVENT WEDNESDAY AFTERNOON THROUGH WEDNESDAY EVENING. THE
TRANSFER OF CYCLOGENESIS TO THE MID ATLANTIC COAST WILL SIPHON AT
LEAST SOME ENERGY AND MOISTURE OUT OF THE GREAT LAKES BUT A WELL
ORGANIZED TROWAL IS SHOWN TO BE IN PLACE OVER OUR AREA WITH A STRONG
HYBRID ATLANTIC/GULF MOISTURE CONVEYOR FEEDING INTO THE NORTH FLANK
OF THE SYSTEM. MODEL FIELDS OF SPECIFIC HUMIDITY INDICATE MORE THAN
ADEQUATE AMOUNTS OF 2-3 G/KG IN THE 850 TO 700 MB LAYER ASSOCIATED
WITH THE TROWAL AXIS. THIS LEAVES DURATION AS THE LIMITING FACTOR AS
FIELDS OF THETA-E INDICATE THE TROWAL SHRINKING EASTWARD QUICKLY BY
MIDNIGHT WEDNESDAY NIGHT. WILDCARDS TO CONSIDER THAT COULD SKEW
AMOUNTS HIGHER INCLUDE THE ACTUAL TIMING OF EAST COAST TRANSFER,
MESOSCALE BANDS WITHIN THE TROWAL, AND LAKE ENHANCEMENT. THE
POTENTIAL FOR LAKE ENHANCEMENT WILL BE THE MOST LIKELY EXTRA
CONTRIBUTOR BUT THAT WILL TEND TO STRETCH THE EVENT WELL INTO
THURSDAY AS SYNOPTIC FORCING WANES. THIS WILL CONTINUE TO BE
EVALUATED BUT THE PREPONDERANCE OF EVIDENCE FOR THIS FORECAST
PACKAGE, ALONG WITH MODEL SOUNDING DERIVED SNOW RATIO AVERAGING
11:1, SUGGESTS STORM TOTALS WILL REMAIN MOSTLY BELOW 6 INCHES DURING
THE 12 TO 18 HOUR EVENT ENDING BY SUNRISE THURSDAY.
AFTER A BREAK DURING THURSDAY AND MOST OF FRIDAY, THE ACTIVE LARGE
SCALE PATTERN WILL CONTINUE WITH THE NEXT PACIFIC SYSTEM REACHING
THE GREAT LAKES TO START THE WEEKEND. EARLY INDICATIONS ARE THIS
SYSTEM WILL BE LESS ORGANIZED AS IT MOVES THROUGH THE GREAT LAKES
BEFORE GAINING STRENGTH ALONG THE EAST COAST TOWARD SUNDAY.
MARINE...
LIGHT NORTHERLY WINDS TONIGHT OF 15 KNOTS OR LESS WILL TURN EASTERLY
AND BEGIN TO INCREASE ON TUESDAY NIGHT AS A STRONG LOW PRESSURE
SYSTEM LIFTS TOWARD THE REGION FROM THE SOUTH. THE PROLONGED PERIOD
OF ONSHORE FLOW WILL FAVOR ELEVATED WAVE CONDITIONS FOR ALL
NEARSHORE ZONES BETWEEN WEDNESDAY AND THURSDAY MORNING IN ADDITION
TO POTENTIAL FUNNELING INTO SAGINAW BAY. SMALL CRAFT ADVISORIES
APPEAR LIKELY AT THIS TIME. BY WEDNESDAY AFTERNOON INTO WEDNESDAY
NIGHT...GUSTS TO NEAR GALES WILL BE POSSIBLE ACROSS AREA WATERS.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
AVIATION.....KURIMSKI
UPDATE.......KURIMSKI
SHORT TERM...JVC
LONG TERM....BT
MARINE.......JVC
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS BILLINGS MT
802 PM MST WED DEC 26 2012
.SHORT TERM...VALID FOR THU AND FRI...
WEAK UPPER LOW TRACKING ACROSS WYOMING IS SPREADING MAINLY LIGHT
SNOW TO MUCH OF THE AREA THIS EVENING...WITH LOWEST VSBYS AND SOME
MINOR ACCUMULATION OCCURRING FROM SHERIDAN ACROSS SOUTHEAST MT.
LATEST RAP ANALYSIS SHOWS SLOW-MOVING 700MB LOW BETWEEN 4BQ AND
GCC...AND THIS POSITION WILL FAVOR OUR EASTERN PARTS FOR PCPN
TONIGHT. THOUGH ASCENT IS RELATIVELY WEAK...MOIST DENDRITIC LAYER
EXTENDING FROM THE SFC TO NEAR 600MB WILL ALLOW FOR SNOW
PRODUCTION TO BE EFFICIENT...SO SNOW WILL SLOWLY ACCUMULATE...
ESPECIALLY IN THE AFOREMENTIONED AREAS. EXPECT DRIER CONDITIONS IN
OUR WEST AND NORTHWEST PARTS PER ONLY SHALLOW UPSLOPE FLOW AND
NEGLIGIBLE FORCING...AND AS LOW TRACKS EAST THE POTENTIAL FOR
PCPN FROM LIVINGSTON TO HARLOWTON AND JUDITH GAP WILL DECREASE
THROUGH THE NIGHT. ANY ACCUMS IN OUR WEST/NORTHWEST SHOULD STAY
UNDER A HALF INCH...WITH AROUND AN INCH FOR OUR BEARTOOTH
ABSAROKA FOOTHILLS PER UPSLOPE FLOW THERE. ACCUMS IN OUR SOUTHEAST
SHOULD RANGE FROM 1 TO 3 INCHES BY TOMORROW...PERHAPS LOCALLY A
BIT HIGHER OVER THE HILLS. IMPACTS WILL INCLUDE REDUCED VISIBILITY
AND SOME SNOW COVERED ROADS ALONG HIGHWAY 212 FROM LAME DEER TO
BROADUS AND ALZADA...AND PARTS OF I-90 NEAR SHERIDAN AND DAYTON.
BASED ON EVOLUTION OF THIS SYSTEM HAVE LOWERED POPS AND SNOW AMTS
IN OUR WEST/NORTHWEST...AND HAVE MAXED OUT POPS AND RAISED SNOW
ACCUMS A BIT IN OUR SOUTHEAST WHERE PCPN IS ALREADY OCCURRING.
FOR THE CITY OF BILLINGS...IT IS SNOWING LIGHTLY NOW AND THIS
SHOULD CONTINUE FOR MUCH OF THE NIGHT THOUGH WITH ACCUMS OF LESS
THAN AN INCH.
JKL
.LONG TERM...VALID FOR SAT...SUN...MON...TUE...WED...
MINIMAL CHANGES TO THE EXTENDED PERIOD ONCE AGAIN THIS
AFTERNOON...AS MODELS REMAIN IN DECENT AGREEMENT AS TO THE
OVERALL PATTERN. HOWEVER...THE DEVIL IS IN THE DETAILS...AS TIMING
AND MATURATION OF WEATHER SYSTEMS CONTINUE TO BE AN ISSUE.
DEVELOPING UPPER LEVEL RIDGE IS STILL ON TRACK TO START THE
PERIOD...SO TEMPERATURES ARE EXPECTED TO CONTINUE TO INCREASE...BUT
THE KLONDIKE NATURE OF THE CHINOOK AND THE EXPECTED CONTINUED SNOW
COVER WILL KEEP HIGH TEMPERATURES REACHING ONLY AROUND FREEZING
ACROSS THE WESTERN ZONES...AND COOLER EAST. TEMPS WILL DROP BACK
TO THE 20S AGAIN SUNDAY...AS A SHORTWAVE TROF PUSHES THROUGH
NORTHWESTERLY FLOW LATE SATURDAY NIGHT INTO SUNDAY. THIS WILL
BRING A COLD FRONT IN FROM THE NORTH AS A CANADIAN HIGH PRESSURE
SYSTEM BUILD INTO THE AREA. THE SHORTWAVE SHOULD BRING WEAK QG
FORCING ACROSS THE AREA SUNDAY. HOWEVER...STRENGTHENING DOWNSLOPE
NORTHWESTERLY FLOW MAY LIMIT SNOW SHOWERS TO MAINLY MOUNTAINS
LOCATIONS...AND POSSIBLY EASTERN ZONES. DID ADD SOME SLIGHT POPS
INTO THE EAST FOR SUNDAY NIGHT...TO COVER ANY LINGERING SHOWER
ACTIVITY. ADDITIONAL CAVEAT IS THAT MODELS SIGNATURES FOR THE
OPERATIONAL GFS AND EC HAVE COMPLETELY FLIP FLOPPED SINCE 24HRS
AGO...SO STILL NEEDS SOME ATTENTION AS THE SYSTEM MATURES.
ANOTHER UPPER LEVEL RIDGE APPEARS TO BE PROGGED INTO THE REGION FOR
MONDAY THROUGH WEDNESDAY. TIMING OF THIS SYSTEM CONTINUES TO BE AN
ISSUE... BUT MODELS DO APPEAR TO BE COMING INTO BETTER
AGREEMENT. THEREFORE DID WARM UP INHERITED NUMBERS SLIGHTLY FOR
TUESDAY AND WEDNESDAY. BACKDOOR COLD FRONTS MAY BE POSSIBLE IN
THIS PATTERN DEPENDING ON HOW THE DETAILS DEVELOP. AAG
&&
.AVIATION...
LIGHT SNOW AND LOW CEILINGS WILL RESULT IN MVFR/IFR CONDITIONS
ACROSS MUCH OF THE REGION OVERNIGHT. MVFR/IFR CONDITIONS WILL GIVE
WAY TO VFR CONDITIONS ACROSS THE WEST LATER TONIGHT...INCLUDING
KLVM...AS DRIER AIR MOVES INTO THAT REGION. SNOW WILL CONTINUE
ACROSS THE SOUTHEAST THROUGH MUCH OF THURSDAY...KEEPING MVFR/IFR
CONDITIONS IN THE FORECAST FOR KSHR AND KBHK INTO THE AFTERNOON
HOURS. STC
&&
.PRELIMINARY POINT TEMP/POPS...
THU FRI SAT SUN MON TUE WED
-----------------------------------------------------------
BIL 007/018 008/026 015/033 015/025 011/031 014/035 013/036
86/S 01/B 01/N 22/S 11/B 10/N 00/N
LVM 008/024 009/025 012/033 015/024 007/027 012/035 013/032
53/S 11/B 11/N 23/S 21/B 11/N 11/N
HDN 007/017 002/026 011/031 011/025 011/030 014/034 011/035
97/S 11/B 01/B 12/S 11/B 10/B 00/B
MLS 003/012 904/018 005/026 008/021 011/027 012/030 011/032
77/S 11/B 01/B 12/S 21/B 11/B 10/B
4BQ 005/014 903/022 007/030 009/023 007/030 011/035 009/033
+9/S 21/B 01/B 12/S 21/B 10/B 00/B
BHK 001/013 907/016 003/024 007/019 009/025 011/028 009/031
99/S 21/E 01/B 12/S 21/B 11/B 10/U
SHR 007/019 006/028 005/031 007/026 008/030 012/032 008/035
+8/S 11/E 01/U 12/S 21/B 10/B 00/B
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS HASTINGS NE
358 AM CST TUE DEC 25 2012
.SHORT TERM...TODAY THROUGH THURSDAY NIGHT. PRIMARY FORECAST
CONCERN LIES WITH PRECIPITATION CHANCES TODAY AND AGAIN
THURSDAY/THURSDAY NIGHT.
UPPER LEVEL SATELLITE IMAGERY SHOWING THE LOW PRESSURE SYSTEM OF
INTEREST STARTING TO EMERGE FROM THE ROCKIES...ENDING UP ROUGHLY
OVER THE PANHANDLES OF TX/OK BY SUNRISE THIS MORNING. INCREASING
LIFT ASSOCIATED WITH THIS SYSTEM IS GRADUALLY BUILDING NORTH INTO
THE CWA...AND WRN LOCATIONS HAVE JUST RECENTLY STARTED REPORTING
SOME -SN. NO SURPRISES WITH THE SURFACE PATTERN...THE MAIN LOW IS
WELL TO THE SOUTH OF THE CWA...WITH HIGHER PRESSURE SET UP OVER
THE DAKOTAS...RESULTING IN AT TIMES GUSTY NORTHERLY WINDS.
THROUGH THE REST OF THE DAYTIME HOURS...REALLY NO SIGNIFICANT
CHANGES MADE. MODELS CONTINUE TO BE IN GOOD AGREEMENT SHOWING THE
MAIN UPPER LEVEL SLIDING ACROSS THE SRN PLAINS...ALONG/JUST SOUTH
OF THE OK/TX BORDER. THE BETTER CHANCES FOR PRECIPITATION
REMAINS GENERALLY ALONG AND WEST OF HIGHWAY 183...BUT DID MAKE
SOME ADJUSTMENTS TO THE AREAL COVERAGE OF THE POPS. LATEST RUNS OF
MANY OF THE MODELS ARE SHOWING A SLIGHT SOUTHWARD SHIFT TO SOME OF
THE HIGHER QPF VALUES...BRINGING INCREASED SNOWFALL POTENTIAL TO
PORTIONS OF OUR NC KS...AND ADJUSTED THE POPS ACCORDINGLY.
OTHERWISE...THE TIMING REMAINS BASICALLY THE SAME WITH THE MAIN
CHANCES COMING DURING THE MORNING HOURS...AND OVERALL AMOUNTS
DIDNT CHANGE MUCH. THIS AFTERNOON...EXPECTING A QUICK DOWNWARD
TREND IN PRECIPITATION...WITH ANY CHANCES CONFINED TO THE WRN
FRINGE OF THE CWA. AS FAR AS ACCUMULATIONS GO...AREAS WEST OF
HIGHWAY 183 STILL LOOKING AT THE POTENTIAL OF GENERALLY ARND 1-1.5
INCHES...A FEW LOCATIONS COULD POSSIBLY CREEP NEAR 2 INCHES.
BETWEEN HIGHWAY 183 AND 281...A COUPLE TENTHS OF AN INCH /EAST/ UP
TO AN INCH /WEST/ ARE POSSIBLE. EAST OF HIGHWAY 281...NOT
EXPECTING MUCH MORE THAN SOME FLURRIES TO PERHAPS A TENTH OF AN
INCH OR SO. HIGHS FOR TODAY STILL LOOKING TO TOP OUT IN THE
LOWER/MID TEENS...AND WIND SPEED WILL RANGE FROM 10-15 MPH IN THE
NORTH TO 15-20 WITH GUSTS NEAR 25MPH IN THE SOUTH CLOSER TO THE
SFC LOW. CURRENT OBS WHERE SNOW IS STARTING TO FALL ARE SHOWING
THE ADDITION OF WIND IS BRINGING VISIBILITIES DOWN NEAR 2 MILES AT
TIMES...AND THAT TREND WILL REMAIN THE CASE THROUGH THE MORNING
ANYWHERE SNOW FALLS. BRIEF PERIODS OF VISIBILITIES CLOSER TO A MILE
OR LESS WILL BE POSSIBLE...JUST WILL BE DEPENDENT ON HOW MUCH SNOW
IS COMING DOWN.
PRECIPITATION TODAY IS EXPECTED TO COME TO AN END BY THIS
EVENING...WITH DRY CONDITIONS THEN THROUGH THE OVERNIGHT HOURS. A
SURFACE RIDGE AXIS WILL GRADUALLY BUILD INTO THE REGION...AND IS
EXPECTED TO SETTLE IN RIGHT OVER THE CWA BY 12Z
WEDNESDAY...BRINGING LIGHT/VARIABLE TO AT TIMES CALM WINDS. THE
MAIN QUESTION FOR TONIGHT LIES WITH HOW COLD TEMPERATURES ARE
GOING TO GET. LITTLE CONCERNED ABOUT SKIES NOT CLEARING AS MUCH AS
THOUGHT EVEN 24 HOURS AGO...WHICH WOULD KEEP TEMPS FROM FALLING AS
MUCH. DID END UP TRENDING OVERNIGHT LOW TEMPERATURES CLOSER TO THE
MET/MAV GUIDANCE...AND STILL REMAINS BELOW RAW MODEL OUTPUT. THIS
WILL BE SOMETHING FOR THE DAY SHIFT TO LOOK INTO WITH THE NEW
MODELS RUNS...PERHAPS SOME ADDITIONAL UPWARD ADJUSTMENTS MAY BE
NEEDED.
INTO WEDNESDAY...THE DRY FORECAST REMAINS IN PLACE...AS UPPER
LEVEL SHORTWAVE RIDGING SLIDES EAST ONTO AND THROUGH THE PLAINS
BETWEEN SYSTEMS. WILL BE SEEING AN INCREASE IN CLOUD COVER THROUGH
THE DAY AS THE NEXT UPPER LEVEL SYSTEM APPROACHES...AND WINDS WILL
START THE DAY LIGHT WITH THAT SFC RIDGE AXIS IN PLACE...BUT WILL
BECOME MORE SOUTHERLY AS IT SLIDES OFF TO THE EAST. UNFORTUNATELY
NOT GOING TO BE SEEING A BREAK FROM THE BELOW AVERAGE
TEMPERATURES...WITH HIGHS ONLY LOOKING TO TOP OUT IN THE MID/UPPER
TEENS.
LOOKING TOWARD WEDNESDAY NIGHT...AND ESPECIALLY THURSDAY AND
THURSDAY NIGHT...ANOTHER CHANCE FOR ACCUMULATING SNOWFALL COMES TO
THE CWA. AS THE UPPER LEVEL LOW PRESSURE SYSTEM AND TROUGH MOVE
EAST THROUGH THE ROCKIES...MORE SOUTHWESTERLY FLOW DEVELOPS OVER
THE CENTRAL PLAINS. AT THIS POINT...MODELS REMAIN IN DECENT
AGREEMENT KEEPING THINGS DRY PRIOR TO 12Z THURSDAY...BUT IT
WOULDNT TAKE MUCH OF A SHIFT TO END UP NEEDING TO ADD POPS LATE
WEDNESDAY NIGHT. THE BETTER CHANCES REMAIN DURING THE DAYTIME
HOURS THURSDAY AND INTO AT LEAST THE FIRST HALF OF THURSDAY NIGHT.
AT 12Z THURSDAY...THERE REMAIN SOME DIFFERENCES BETWEEN
MODELS...BUT THE LOW LOOKS TO BE OVER OR MOVING INTO THE PANHANDLE
OF NEBRASKA REGION. THROUGH THE DAYTIME HOURS...THE LOW TAKES AN
EASTWARD PATH...AND THE MODEL DIFFERENCES CONTINUE...BUT IN
GENERAL THE LOW SHOULD BE CROSSING THE NORTHERN HALF OF NEBRASKA.
THE MAIN CHANGE MADE TO THE FORECAST WAS TO INCREASE POPS ACROSS
THE NORTHERN HALF OF THE CWA...WITH LIKELY POPS I-80 AND NORTH.
THIS IS ANOTHER PROGRESSIVE SYSTEM...BUT SNOWFALL ACCUMULATIONS OF
ARND 2 INCHES LOOKS POSSIBLE...MAINLY NORTH OF HIGHWAY 92.
PRECIPITATION IS EXPECTED TO COME TO AN END BY 12Z FRIDAY.
.LONG TERM...FRIDAY THROUGH MONDAY. TEMPERATURES WILL BE THE MAIN
CHALLENGE THROUGH THIS PERIOD.
SHORTWAVE UPPER LEVEL RIDGING WILL DEVELOP ACROSS THE CENTRAL
PLAINS FRIDAY AND THROUGH WEEKEND. THIS SHOULD GIVE US PLENTY OF
SUNSHINE FOR THE PERIOD AND DRY CONDITIONS. RETURN SOUTHWEST FLOW
BY LATER SATURDAY WILL HELP MODERATE DAYTIME TEMPERATURES INTO THE
20S...STILL BELOW NORMAL BUT A NICE RESPITE FROM THE CURRENT COLD
SPELL. THE RIDGE IS REPLACED BY A WEAK SHORTWAVE WORKING SOUTH
FROM CANADA ON MONDAY. WHILE SOME FLURRIES MAY BE POSSIBLE...TOO
EARLY TO THINK MEASURABLE PRECIPITATION. THE MAIN INFLUENCE WILL
BE ANOTHER REINFORCING SHOT OF AN ARCTIC AIR MASS FOR
MONDAY/TUESDAY. HIGH TEMPERATURES MAY SLIP BACK A BIT...AND THAT
IS THE TREND DEPICTED IN MONDAY/S HIGH TEMPERATURES...SUGGESTING 3
TO 5 DEGREES COOLER THAN SUNDAY.
AFTER A CHILLY START TO NEXT WEEK...SIGNS ARE SHOWING THAT A
WARMING CHINOOK WIND MAY DEVELOP IN CENTRAL CANADA AS UPPER
LEVEL RIDGING PUSHES INTO THAT AREA. THIS COULD SPELL A DEVELOPING
WESTERLY BREEZE WORKING ITS WAY SOUTH FROM THE CANADIAN PROVINCES.
THIS WOULD SETTLE INTO THE AREA NEXT WEDNESDAY/THURSDAY
POTENTIALLY...AND GIVE US OUR BEST SHOT AT SOME MELTING IN THE
NEAR FUTURE. IT APPEARS TEMPERATURES WILL BE NEAR NORMAL IN THE 10
TO 15 DAY PERIOD...TEMPERED SOME BY CURRENT SNOWPACK.
&&
.AVIATION...06Z TAF. THE ENTIRE FORECAST PERIOD WILL HAVE MID
LEVEL CEILINGS RANGING FROM 3500 FEET TO 12K FEET. STARTING TO
SEE EVIDENCE OF SECOND SNOW AREA DEVELOPING ON RADAR TO THE
SOUTHWEST OF KGRI...SIMILAR TO TRENDS ON THE HRRR AND WRF MODELS.
THIS SHOULD EVENTUALLY BE GRAND ISLAND/S SNOW MAKER..ALBEIT VERY
LIGHT. EXPECTING THE SNOW TO DEVELOP PRIOR TO SUNRISE AND LINGER
THROUGH LATE MORNING...WITH POSSIBLY SOME BRIEF PERIODS OF MVFR
VISIBILITIES. ANY SNOW ACCUMULATIONS WILL BE IN THE RANGE OF A
SKIFF OR SO. A STEADY NORTH NORTHEAST WILL DROP OFF AROUND SUNSET
AS CEILINGS SLOWLY LIFT AS WELL.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1115 PM CST MON DEC 24 2012
.AVIATION...06Z TAF. THE ENTIRE FORECAST PERIOD WILL HAVE MID
LEVEL CEILINGS RANGING FROM 3500 FEET TO 12K FEET. STARTING TO
SEE EVIDENCE OF SECOND SNOW AREA DEVELOPING ON RADAR TO THE
SOUTHWEST OF KGRI...SIMILAR TO TRENDS ON THE HRRR AND WRF MODELS.
THIS SHOULD EVENTUALLY BE GRAND ISLAND/S SNOW MAKER..ALBEIT VERY
LIGHT. EXPECTING THE SNOW TO DEVELOP PRIOR TO SUNRISE AND LINGER
THROUGH LATE MORNING...WITH POSSIBLY SOME BRIEF PERIODS OF MVFR
VISIBILITIES. ANY SNOW ACCUMULATIONS WILL BE IN THE RANGE OF A
SKIFF OR SO. A STEADY NORTH NORTHEAST WILL DROP OFF AROUND SUNSET
AS CEILINGS SLOWLY LIFT AS WELL.
&&
.PREV DISCUSSION... /ISSUED 551 PM CST MON DEC 24 2012/
AVIATION...00Z KGRI TAF...CIGS ARE EXPECTED TO LOWER AT THE
TERMINAL OVERNIGHT WITH NORTHEASTERLY WINDS BECOMING MORE
NORTHERLY BY MIDNIGHT. THERE IS A SMALL PROBABILITY FOR SOME MVFR
CIGS/VSBYS IN -SN AFT ABOUT 25/09Z...BUT KEPT IN A PROB30 GROUP
FOR NOW AS BETTER CHANCES FOR SOME LIGHT SNOWFALL APPEARS FURTHER
WEST...WITH MAINLY FLURRIES AND NO VISIBILITY RESTRICTIONS
EXPECTED AT THE TERMINAL FOR THE TIME BEING.
PREV DISCUSSION... /ISSUED 342 PM CST MON DEC 24 2012/
SHORT TERM...CHRISTMAS EVE THROUGH CHRISTMAS DAY
MAIN STORY: CLOUDY THIS CHRISTMAS EVE WITH LIGHT SNOW DEVELOPING
LATE AND CONTINUING INTO CHRISTMAS DAY...MAINLY W OF THE TRI-
CITIES. AN INTENSIFYING STORM TO THE S WILL COMBINE WITH BITTER
COLD TO RESULT IN NASTY WIND CHILLS AND THE COLDEST CHRISTMAS IN
16 YRS!
ZFP/AFM/PFM AND UPDATED HWO HAVE ALL POSTED.
UPPER-LEVELS: SHORT-WAVE TROF AND ASSOCIATED 130 KT TROPOPAUSE JET
IS MOVING THRU THE 4 CORNERS ATTM. THIS WILL INITIATE LEE
CYCLOGENESIS...BUT SFC LOW WILL TRACK FAR TO THE S OVER TX.
HOWEVER...THE TROF/JET WILL INDUCE UPSLOPE AS MID-LEVEL
CIRCULATION CLOSES OFF. THIS WILL RESULT IN SOME -SN LATE TNGT
INTO CHRISTMAS DAY...ENHANCING THE HOLIDAY FEEL BUT THREATENING
SOME SLIPPERY TRAVEL.
REST OF THIS AFTN: M/CLOUDY WITH AREAS S OF HWY 24 OVER N-CNTRL KS
FLIRTING WITH P/CLOUDY. ANOTHER COLD DAY WITH TEMPS NEARLY 20F
BELOW NORMAL.
TONIGHT: BECOMING CLOUDY FOR ANY AREAS NOT COMPLETELY OVC BY SUNSET.
POSSIBLY SOME -SN MOVING IN W OF HWY 283 AFTER MIDNIGHT. NE WINDS
GRADUALLY INCREASE TO 10-20 MPH BY MIDNIGHT AND 15-25 MPH AFTER 3
AM.
LOW TEMPS ARE A 67/33 BLEND OF MAV/MET MOS. THEN NUDGED UP ORD AND
SURROUNDING AREAS 2F. COULD GET BURNED ON THIS IN NE ADVECTION BUT
HARD TO BELIEVE ORD IS COLDER TNGT THAN WHAT THE LOW WAS THIS AM.
CHRISTMAS DAY: CLOUDY AND BITTERLY COLD WITH A BITING NE WIND AS
LOW DEVELOPS WELL S OF THE FCST AREA. PERIODS OF -SN MAINLY ALONG
AND W OF HWY 183. USED 09Z SREF TO ASSIST WITH POPS.
COULD SEE FLURRIES OR A TOUCH OF -SN FROM THE TRI-CITIES E.
SNOW: CURRENT EXPECTATION IS AROUND 1" ALONG AND W OF HWY 283. LESS
THAN 1" BETWEEN HWY 283 AND 183. THEN JUST A DUSTING POSSIBLE AS FAR
E AS ORD-KEARNEY-SMITH CTR KS-OSBORNE KS.
SNOW RATIO: LOW CONFIDENCE. STAYED CLOSE TO CLIMO BUT FEELING IS
THAT IT WILL BE LOWER. LIFT IS MOSTLY ABOVE THE DGZ PER CROSS
SECTIONS...AND VERY WEAK IN THE DENDRITIC GROWTH ZONE /DGZ/. THIS
SUGGESTS PRIMARILY PLATE HABITS OR SMALL DENDRITES. INCREASED FLAKE
DENSITY SUPPORTS A LOWER RATIO.
WHERE CAN THIS FCST BREAK DOWN: HOW FAR E WILL SNOW FALL? AND HOW
FAR E WILL 1" OCCUR? THE 12Z NAM-ARW IS THE FARTHEST E WITH ITS .1
QPF...TO KEARNEY/SMITH CTR. NOT TO SAY IT CAN/T HAPPEN BUT SREF
PROBS FOR AT LEAST .1 ARE GREATEST W OF HWY 283. SO THIS FCST IS
CONSERVATIVE. MAY NOT BE FAR ENOUGH E. HIGHEST SREF PROBS FOR 1" OF
ACCUM IS OVER EXTREME WRN DAWSON COUNTY BUT THIS IS PROBABLY TOO
CONSERVATIVE.
WIND CHILLS: 0 TO -10F TNGT. -7 TO -10F CHRISTMAS DAY.
DRESS VERY WARMLY IF YOU HAVE PLANS TO CAROL OUTSIDE OR TRAVEL TO
HOLIDAY PARTIES. THIS KIND OF COLD WILL BE DANGEROUS!
CLIMATE: FOR THOSE INTERESTED OUR FCST TEMPS FOR TOMORROW ARE AN
INTERESTING COMPARISON WITH PREVIOUS CHRISTMAS EXTREMES. PLEASE SEE
THE EXCELLENT WEB STORY ON CHRISTMAS CLIMO ON OUR TOP NEWS OF THE
DAY FOR THE DETAILS. BOTTOM LINE...THIS WILL BE AMONG THE TOP TEN
COLDEST CHRISTMAS DAYS ON RECORD FOR THE HIGH TEMP AND DAILY AVG
TEMP. THE GRI HIGH TEMP CHRISTMAS 1996 WAS ONLY 11F. WE ARE
CURRENTLY FCSTG 11F. IF THIS FCST IS CORRECT THIS WILL TIE FOR THE
4TH COLDEST CHRISTMAS ON RECORD AT GRI.
LONG TERM...CHRISTMAS DAY NIGHT THROUGH MONDAY/NEW YEARS EVE. AS A
LIGHT SNOW EVENT RAPIDLY WRAPS UP CHRISTMAS DAY...FOCUS IS ON THE
NEXT ROUND OF SNOW MOVING IN ON THURSDAY. STARTING WITH CHRISTMAS
DAY NIGHT...BOTH THE SOUTHERN PLAINS CLOSED SYSTEM AND WEAKER
NORTHERN STREAK TROUGH TREK EASTWARD CHRISTMAS DAY NIGHT. UNDER
MORE INFLUENCE OF THE NORTHERN STREAM TROUGH...THE MID/UPPER TROUGH AXIS
DOES NOT PASS TO OUR EAST UNTIL OVERNIGHT AND WOULD NOT BE SURPRISED
TO SEE A FEW FLURRIES LINGERING BRIEFLY INTO THE EVENING...HOWEVER
AS AXIS SHIFTS EASTWARD INTO DRIER AIR...ANY LINGERING FLURRIES
SHOULD WIND DOWN RATHER QUICKLY.
LITTLE CHANGE IN THE FRIGID ARCTIC AIRMASS ON WEDNESDAY...WITH DRY
CONDITIONS IN SHORTWAVE RIDGING...BUT UNDER THE INFLUENCE OF A
1030MB SURFACE HIGH PRESSURE SYSTEM. TEMPS WILL STRUGGLE WITH JUST
TEENS FORECAST FOR HIGHS...OVERNIGHT WIND CHILLS IN THE TEENS BELOW
ZERO...AND DAYTIME WIND CHILLS IN THE SINGLE DIGITS. WEDNESDAY
NIGHT INTO THURSDAY...THE SURFACE RIDGE SHIFTS EASTWARD WITH SFC LOW
PRESSURE DEEPENING ALONG THE HIGH PLAINS WHILE UPSTREAM UPPER LOW
MOVES FURTHER INTO THE NORTHERN/CENTRAL ROCKIES. A 130KT JET ROUNDS
BASE OF TROUGH AND NOSES NORTH ONTO THE CENTRAL PLAINS WITH
DIVERGENCE ALOFT INCREASING BY THURSDAY MORNING. ISENTROPIC LIFT AS
INDICATED ON THE 290K SURFACE IS ALSO ON THE INCREASE
THURSDAY...ESPECIALLY ACROSS OUR NORTHERN ZONES AHEAD OF THE
APPROACHING CLOSED UPPER LOW SYSTEM. SNOW IS EXPECTED TO DEVELOP
DURING THE DAY ON THURSDAY...AND CONTINUE INTO THURSDAY NIGHT AS THE
SYSTEM TRACKS ACROSS NEBRASKA. BASED ON THE CURRENT TRACK OF THE
SYSTEM...THE BEST SNOW CHCS FAVOR LOCATIONS IN
NEBRASKA...PARTICULARLY NORTH OF INTERSTATE 80. GIVEN THE COLD
AIRMASS...SNOW RATIOS WILL BE RATHER HIGH AND SNOW ACCUMULATIONS
LOOK LIKELY. WILL AIM FOR SNOW AMOUNTS OF AN INCH OR TWO IN OUR FAR
NORTHERN ZONES ON THURSDAY...WITH LESSER AMOUNTS TO THE SOUTH.
THE UPPER LOW EXITS THE CENTRAL PLAINS TO THE UPPER MIDWEST REGION
THURSDAY NIGHT/FRIDAY WITH SNOWFALL ENDING W/E. STILL UNDER
INFLUENCE OF AN UPPER TROUGH FRIDAY AND WITH THE NEW SNOWFALL...COLD
AIRMASS IN PLACE...TEMPS WILL CONTINUE TO STRUGGLE. UPPER TROUGH
FINALLY DEPARTS HEADING INTO THE WEEKEND ALLOWING FOR HEIGHTS TO
RISE WITH UPPER RIDGING PROGGED ACROSS THE CENTRAL PLAINS FOR THE
WEEKEND. THE ARCTIC AIR BEGINS TO DISLODGE AND TEMPS IN THE 20S
LOOK PROBABLE FOR HIGHS. ALTHOUGH JUST BEYOND THE EXTENDED...ECMWF
ADVERTISES ANOTHER SURGE OF ARCTIC AIR TO ARRIVE IN TIME FOR NEW
YEARS DAY WITH A 1037MB SURFACE HIGH SETTLING IN.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1013 PM EST WED DEC 26 2012
.SYNOPSIS...
A STRONG WINTER STORM WILL IMPACT THE AREA TONIGHT LEADING TO
HEAVY SNOW ACCUMULATIONS ACROSS THE ENTIRE FORECAST AREA. WRAP
AROUND MOISTURE WILL THEN RESULT IN CONTINUED SNOWS FOR MUCH OF
CENTRAL NEW YORK ON THURSDAY BEFORE HIGH PRESSURE SLOWLY BUILDS
INTO THE AREA TOWARDS THE CONCLUSION OF THE WEEK.
&&
.NEAR TERM /THROUGH THURSDAY/...
10 PM UPDATE... WELL DEFINED AND NARROW DRY SLOT CONTS ITS NWD
CHARGE ATTM...ALG THE I-81 CORRIDOR. THUS...PCPN HAS AT LEAST
TEMPORARILY TAPERED OFF...AND ALSO MIXED WITH SLEET/-FZRA...FROM
ABT KBGM SWD TWDS W-B/SCRANTON. MEANWHILE...INTERESTINGLY...HVYR
PCPN (MAINLY SNOW) CONTS ACRS THE WRN CATSKILLS AND
POCONOS...LIKELY IN RESPONSE TO INCRD FGEN FORCING...ASSOCD WITH
DVLPG SFC/MID-LVL CYCLONES ACRS THE DELMARVA RGN. ALSO...HVY SNOW
PERSISTS TO OUR W AND N...TIED TO ORIGINAL BAND OF STG ISEN LIFT.
WHAT HAPPENS FROM HERE ON IN?? WELL...THE LATEST RAPID REFRESH
DATA...ALG WITH INCOMING 00Z NAM/GFS OUTPUT...HAS COME INTO LINE
PRETTY WELL...SUGGESTING THAT HVYR PCPN WILL BE MOST SUSTAINED
JUST W OF THE I-81 CORRIDOR IN THE 06-10Z TIME FRAME...AS THE BEST
FORCED LIFT TENDS TO CONSOLIDATE IN THIS RGN. HVYR PCPN NOW ACRS
OUR SERN ZNS...SHOULD HAVE A TENDENCY TO BECOME LGTR AND MORE
SPOTTY AFTER MIDNIGHT...UNDERNEATH EXPANDING DRY SLOT ALOFT.
AS LOW-LVL CAA/VEERING BLYR WINDS START TO KICK IN TWDS
DAYBREAK...AS THE MAIN STORM BCMS MORE VERTICALLY STACKED NEAR
NYC...A GENERAL AND LGTR WRAP-ARND SNOW PATN SHOULD BEGIN TO
BECOME ESTABLISHED.
AGN...BOTTOM LN...NOT MUCH CHG MADE TO OVERNIGHT SNOW ACCUMS/STORM
TOTALS. HVYR AMTS...AS EXPECTED...WILL LIKELY END UP OVER WRN AND NRN
PTNS OF THE FA. SOME 6"+ SNOW TOTALS ALSO SEEN AS FAR SEWD AS SXNS
OF THE TWIN TIERS/CHENANGO/OTSEGO CNTYS...AND SULLIVAN/PIKE/WAYNE
CNTYS IN THE POCONOS/WRN CATSK.
PREV UPDATE... 8 PM UPDATE... RADAR/SAT LOOPS SHOW A WELL DEFINED
DRY SLOT HEADING NWD THROUGH ERN PA ATTM. THE LATEST RAPID REFRESH
MODEL RUNS...AND ALSO THE 18Z NWP GUIDANCE SHOW THIS FEATURE...BUT
HAVE NOT QUITE CAUGHT ON TO ITS QUICK NWD MOVEMENT. THUS...WE`VE
SPED UP THE TRANSITION FROM STEADY HVY SNOW...TO LGTR SNOW...OR A
LGT MIX...GENERALLY OCCURRING FROM 00-03Z...ALG AND JUST E OF THE
I-81 CORRIDOR.
ALSO...THE CHARACTER OF THE RADAR ECHOES...PLUS
PLENTIFUL SPOTTER/PUBLIC REPORTS...SHOW A HODGE-PODGE OF
SNOW...SLEET...FZRA BASICALLY ALG AND S OF ROUTE 6 IN NRN PA ATTM.
THIS AREA OF MIXED PCPN WILL PROBABLY EXTEND TO ABT THE I-88
CORRIDOR IN SRN NY TWDS 03-04Z...BUT WE DON`T EXPECT IT TO MOVE
ANY FARTHER TO THE N OR W.
AT THIS JUNCTURE...WE DON`T SEE A LOT OF EVIDENCE THAT THE ERLY
FLOW/TERRAIN INDUCED PCPN SHADOWING...CONSISTENTLY SHOWN BY MANY
OF OUR HI-RES MODELS FOR THIS EVE...HAS DVLPD...OR WILL DVLP.
WE`LL SEE HOW THE DRY SLOT ADVANCING ACRS PA DVLPS LTR THIS
EVE...IN THIS REGARD.
BOTTOM LN...WE`RE NOT MAKING ANY SUBSTANTIVE CHGS TO OUR SNOW
TOTALS. INITIAL BURST OF VERY HVY SNOW IN OUR FAR SRN ZNS IN THE MID TO
LATE AFTN HRS...HAVE BROUGHT SNOW TOTALS INTO THE 3-6" RANGE ATTM.
GIVEN MIXED PCPN THESE AREAS CURRENTLY...TOTALS WILL LIKELY NOT GO
A GREAT DEAL HIGHER. ACRS THE TWIN TIERS...VERY HVY SNOW THE LAST
SVRL HRS...IS LIKELY TO SLOW DOWN A BIT THROUGH ABT
06Z...ESPECIALLY S AND E OF A TOWANDA TO KBGM TO ONEONTA LN. SNOW
TOTALS HAVE RANGED FROM 4-8" IN MANY LOCALES THROUGHOUT THESE
AREAS SO FAR.
FOR MANY OF OUR NRN AND WRN ZNS...HVY SNOW BANDS WILL CONTINUE TO
ROTATE ACRS THROUGH AT LEAST 06Z...AS MID-LVL FGEN MAXIMIZES...AND
THETA-E LR`S ALOFT DECREASE ON THE LEADING EDGE OF THE DRY SLOT.
ISOLD THUNDER-SNOW NOT OUT OF THE QUESTION...AND IN FACT...SOME
OF THIS HAS ALREADY BEEN REPORTED IN CHENANGO CNTY. STORM TOTALS
OF A FOOT OR MORE WILL BE MOST PROBABLE THESE PTNS OF THE FA.
OVERALL...ONLY MINOR TWEAKS MADE...TO BEST REFLECT THE LATEST
RADAR/TEMP TRENDS. NEAR-TERM SPS`S AND FREQUENT WSW UPDATES WILL
CONTINUE TO BE ISSUED.
EARLIER DISC... CONDITIONS RAPIDLY DETERIORATING ACROSS THE AREA THIS
AFTERNOON AS LONG ADVERTISED WINTER STORM GETS UNDERWAY. REGIONAL
WATER VAPOR IMAGERY SHOWING MAIN MID-LEVEL CIRCULATION SLIDING
ACROSS THE EASTERN TN/KY BORDER THIS AFTERNOON...WITH NOTABLE DRY
SLOT BEGINNING TO WORK NORTH TOWARDS PIT AS SYSTEM CONTINUES THE
OCCLUSION PROCESS. LATEST RUC TROP PRESSURE FIELD SHOWS MAIN WAVE
NOW TAKING ON A NEGATIVE TILT WHICH SUGGEST UPPER FEATURE IS
REACHING MATURITY. MEANWHILE ALONG THE SURFACE...SECONDARY LOW
PRESSURE DEVELOPMENT NOW TAKING SHAPE ACROSS THE NORTH CAROLINA
PIEDMONT REGION...WITH SFC PRESSURE FIELDS REVEALING A NOTABLE
COLD AIR DAMMING SIGNATURE ALONG THE EASTERN SPIN OF THE
APPALACHIANS. IF NOTHING LESS...THE PRESENCE OF THIS SIGNATURE
WILL HELP ENSURE CONDITIONS ARE PRE-CONDITIONED FOR A ROUND OF
HEAVY SNOWFALL ACROSS THE FCST AREA TONIGHT AS WARM AIR ADVECTION
FORCING INCREASES IN ADVANCE OF THE SECONDARY LOW PRESSURE
SYSTEM/S MOVEMENT UP THE EAST COAST.
THE ABOVE SAID...LATEST RADAR TRENDS SHOWING SNOW MAKING STEADY
PROGRESS NORTHWARD THIS AFTERNOON WITH SNOW ALREADY BEING
REPORTED AT BOTH ELM AND AVP. QUICK INSPECTION OF RUC LAYERED
THETA-E LAPSE RATES SUGGEST A FAIR AMOUNT OF CONDITIONAL
INSTABILITY EXISTS ALOFT WHICH WILL LEAD TO SNOWFALL RATES ON THE
ORDER OF 2-3`/HR UNDER THE HEAVIEST ACTIVITY. DESPITE THE FACT THE
STORM IS ALREADY ONGOING ACROSS THE AREA...A FAIR AMOUNT OF MODEL
UNCERTAINTY STILL EXISTS WITH EXPECTED CONDITIONS OVERNIGHT AS THE
SECONDARY LOW PASSES TO OUR SOUTH AND EAST. WHAT DOES APPEAR FOR
CERTAIN IS THAT THE HEAVIEST SNOWFALL WILL OCCUR BETWEEN NOW AND
06Z AS THE MAIN AREA OF FRONTOGENESIS AND WARM AIR ADVECTION
FORCING LIFTS THROUGH THE FCST AREA. UNFORTUNATELY THIS WILL OCCUR
DURING THE AFTERNOON COMMUTE WHICH WILL UNDOUBTEDLY MAKE THINGS
DICEY FOR THOSE HEADING HOME THIS EVENING. MODELS CONTINUE TO
INSIST ON THE PREVIOUSLY MENTIONED DRY SLOT MOVING NORTH INTO OUR
AREA AFTER 06Z WHICH WILL LEAD TO A FAIR AMOUNT OF DRYING WITHIN
THE DENDRITIC SNOW GROWTH REGION. AS A RESULT...WE EXPECT TO SEE
THE HEAVY SNOW ZONE GRADUALLY ROTATE TO THE WEST WITH TIME AS A
POORLY DEFINED DEFORMATION AXIS ATTEMPTS TO FORM AFTER 06Z.
FURTHER TO THE EAST...PRONOUNCED DRY AIR ALOFT WILL LIKELY LEAD TO
A GRADUAL DECREASE IN SNOWFALL INTENSITY FOR THE SUSQUEHANNA
VALLEY REGION OF CENTRAL NY AND POINTS SOUTH TO INCLUDE THE TWIN
TIERS...POCONOS...AND LOWER WYOMING VALLEY. DESPITE THE PRESENCE
OF THE DRY SLOT...FORECAST MODELS CONTINUE TO PRODUCE LIGHT QPF
ACROSS THESE REGIONS WHICH LEADS US TO BELIEVE THAT FREEZING RAIN
AND PERHAPS SOME SLEET WILL BEGIN FOR THESE AREAS TOWARDS THE
EARLY MORNING HRS. IF THIS WERE TO OCCUR AS ADVERTISED...A FAIRLY
HEALTHY ICING EVENT MAY HAPPEN FOR THOSE LOCATIONS. FOR NOW WE
EXPECT THE HEAVIEST ICING TO OCCUR ACROSS THE WYOMING VALLEY AND
SOUTHERN POCONOS WHERE A QUARTER INCH OR MORE OF ICE WILL BE POSSIBLE.
ANOTHER INTRIGUING ASPECT OF THIS STORM IS THAT ALL MODELS TO
INCLUDE THE LOWER RESOLUTION ECMWF SHOW A SHADOWING EFFECT JUST
WEST OF THE CATSKILLS AFTER 06Z THIS EVENING. THIS SEEMS PLAUSIBLE
TO SOME DEGREE AS A STRONG EASTERLY LOW-LEVEL JET OF 70+KTS
IMPINGES ON THE MOUNTAIN RANGE. FOR NOREASTER TYPE EVENTS THIS
SEEMS VERY UNUSUAL HOWEVER WITH ALL SHORT TERM MODEL PROGS
CONTINUING TO INSIST THIS WILL OCCUR...HAVE ELECTED TO LOWER
SNOWFALL TOTALS ACROSS THE WESTERN CATSKILLS JUST A TAD.
SO TO SUM THINGS UP...THE HEAVIEST SNOWS ARE EXPECTED FROM THE
CHEMUNG RVR VLY NORTHEAST TROUGH THE FINGER LAKES AND WESTERN
MOHAWK VALLEY. ACROSS THESE LOCATIONS...ANYWHERE BETWEEN 10-14"
WILL BE POSSIBLE. FURTHER SOUTH AND EAST...8-10" ARE FORECAST
ACROSS THE TWIN TIERS AND WESTERN CATSKILLS...WITH 4-6" EXPECTED
FOR THE SOUTHERN CATSKILLS...POCONOS AND LOWER WYOMING VLY. NO
CHANGES MADE TO INHERITED HAZARDS WITH THE EXCEPTION OF BEEFING UP
THE WORDING FOR POTENTIAL ICE ACCUMULATIONS ACROSS THE SOUTH.
FOR THURSDAY...EXPECT SOME LINGERING WRAP AROUND MOISTURE TO LEAD
TO CONTINUED SNOW ACROSS PORTIONS OF UPSTATE NY. H85 TEMPS LOOK A
TAD TOO WARM TO RESULT IN ANY SIGNIFICANT LAKE ENHANCEMENT. WILL
CONTINUE TO CARRY LIKELY POPS ACROSS THE NORTH WITH SLGT CHC-CHC
TO THE SOUTH.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY/...
STORM MOVES AWAY FROM THE AREA THURSDAY NIGHT. EXPECT SOME LIGHT
LAKE EFFECT SNOW SOUTH-SOUTHEAST OF LAKE ONTARIO WITH A 320 TO 325
DEGREE FLOW AND SOME LINGERING MOISTURE. HOWEVER WITH MARGINAL
TEMPERATURES AROUND -8 TO -10 DEGREES C AT 850 MB AND INVERSION HGTS
GENERALLY BELOW 5000 FEET EXPECT ONLY LIGHT ACCUMULATIONS... MAYBE
AROUND 2 INCHES ACROSS CENTRAL NY DOWN THROUGH AREAS SOUTHEAST OF
THE FINGER LAKES. DRYING MOVES IN WITH A WEAK RIDGE OF HIGH PRESSURE
ON FRIDAY PUTTING AN END TO ANY LINGERING LIGHT SNOW SHOWERS OR
FLURRIES DURING THE DAY.
NEXT SYSTEM APPROACHES THE AREA LATER FRIDAY NIGHT INTO SATURDAY.
MODEL CONSENSUS WITH THIS NEXT SYSTEM INDICATES A WEAK INVERTED
SURFACE TROUGH TRACKING ACROSS THE AREA WITH SOME LIGHT SNOW... BUT
SIGNIFICANT DEVELOPMENT OF THE SURFACE LOW DOES NOT OCCUR UNTIL THE
STORM IS WELL EAST OF THE MID-ATLANTIC COAST. THEREFORE HEAVY SNOW
DOES NOT APPEAR LIKELY AT THIS TIME.
.LONG TERM /SUNDAY THROUGH TUESDAY...
GFS AND ECMWF ARE IN REASONABLY GOOD AGREEMENT WITH THE OVERALL
PATTERN DURING THIS PERIOD INDICATING NORTHWEST FLOW WITH A SERIES
OF WEAKLY ORGANIZED CLIPPER SYSTEMS LIKELY ALONG WITH SOME LAKE EFFECT
SNOW. HOWEVER AT THIS POINT THERE IS NO INDICATION FOR ANY MAJOR
SYNOPTIC SCALE SYSTEMS THAT WOULD TAP GULF MOISTURE. TIMING OF THESE
INDIVIDUAL SYSTEMS WILL BE DIFFICULT BEYOND SUNDAY... BUT RIGHT NOW
THE BEST CHC FOR A WEAKLY ORGANIZED CLIPPER-LIKE SYSTEM COULD BE NEW
YEAR`S EVE INTO NEW YEAR`S DAY... WHICH WOULD BE FOLLOWED BY AN
ENHANCED PERIOD OF LAKE EFFECT SNOW. TEMPERATURES THROUGH THE PERIOD
WILL AVERAGE NEAR TO BELOW NORMAL... WITH HIGHS MAINLY IN THE MID
20S TO LOWER 30S AND LOWS IN THE TEENS. HAVE GONE WITH HPC GUIDANCE
THROUGH THE PERIOD INDICATING BEST CHANCES FOR SNOW WILL BE OVER
CENTRAL NY WITH SMALLER CHANCES TOWARD NORTHEAST PA.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
GFS AND ECMWF ARE IN REASONABLY GOOD AGREEMENT WITH THE OVERALL
PATTERN DURING THIS PERIOD INDICATING NORTHWEST FLOW WITH A SERIES
OF WEAKLY ORGANIZED CLIPPER SYSTEMS LIKELY ALONG WITH SOME LAKE EFFECT
SNOW. HOWEVER AT THIS POINT THERE IS NO INDICATION FOR ANY MAJOR
SYNOPTIC SCALE SYSTEMS THAT WOULD TAP GULF MOISTURE. TIMING OF THESE
INDIVIDUAL SYSTEMS WILL BE DIFFICULT BEYOND SUNDAY... BUT RIGHT NOW
THE BEST CHC FOR A WEAKLY ORGANIZED CLIPPER-LIKE SYSTEM COULD BE NEW
YEAR`S EVE INTO NEW YEAR`S DAY... WHICH WOULD BE FOLLOWED BY AN
ENHANCED PERIOD OF LAKE EFFECT SNOW. TEMPERATURES THROUGH THE PERIOD
WILL AVERAGE NEAR TO BELOW NORMAL... WITH HIGHS MAINLY IN THE MID
20S TO LOWER 30S AND LOWS IN THE TEENS. HAVE GONE WITH HPC GUIDANCE
THROUGH THE PERIOD INDICATING BEST CHANCES FOR SNOW WILL BE OVER
CENTRAL NY WITH SMALLER CHANCES TOWARD NORTHEAST PA.
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
IFR THROUGH 18Z THURSDAY DUE TO STRONG STORM SYSTEM AFFECTING THE AREA.
VSBYS WILL RANGE FROM 1/2 TO 2 MILES THROUGH THE OVERNIGHT PERIOD
OCCASIONALLY DROPPING TO 1/4SM. LIGHT TO MODERATE SNOW WILL
CONTINUE THROUGH NY TERMINALS WITH KAVP BECOMING MIXED
PRECIPITATION IN THE NEXT 1-2 HOURS AND LIGHTENING UP, EVENTUALLY
RISING TO MVFR AFTER 05Z. SNOW WILL BEGIN TO BECOME LIGHTER AFTER
05Z BUT STILL REMAIN AROUND IFR.
SNOW WILL BECOME SHOWERY DURING THE DAY THURSDAY WITH MVFR TO OCNL
IFR CONDITIONS PERSISTING THROUGH THE DAY IN CENTRAL NY. MVFR TO
OCNL VFR CONDITIONS CAN BE EXPECTED AT AVP WITH LIGHT SNOW
SHOWERS DURING THE AFTERNOON.
WINDS WILL BE E-NE AROUND 10-20 KTS TONIGHT THEN SHIFTING TO NW AT 10
TO 20 KTS WITH OCCASIONAL GUSTS TO 25 KTS ON THURSDAY.
OUTLOOK...
THUR NGT...MVFR/IFR IN SNOW SHOWERS ESPECIALLY OVER CENTRAL NY.
FRI...MAINLY VFR...MVFR/IFR POSSIBLE NORTHERN TERMINALS IN LAKE
EFFECT SNOW.
SAT...ANOTHER POSSIBLE WINTER SYSTEM AND THUS POSSIBLE IFR/MVFR.
SUN...MVFR/IFR POSSIBLE AT FOR CNY TERMINALS IN DEVELOPING LAKE
EFFECT SN.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...WINTER STORM WARNING UNTIL 1 PM EST THURSDAY FOR PAZ038>040-
043-044-047-048-072.
NY...WINTER STORM WARNING UNTIL 1 PM EST THURSDAY FOR NYZ009-
015>018-022>025-036-037-044>046-055>057-062.
&&
$$
SYNOPSIS...CMG
NEAR TERM...CMG/MLJ
SHORT TERM...DGM
LONG TERM...PVN
AVIATION...PVN
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
917 PM EST WED DEC 26 2012
.SYNOPSIS...
A POTENT WINTER STORM WILL IMPACT THE ENTIRE REGION TONIGHT
THROUGH THURSDAY NIGHT PRODUCING WIDESPREAD HEAVY SNOWS WITH
AMOUNTS OVER A FOOT. GUSTY WINDS WILL ALSO OCCUR ALONG THE WESTERN
SLOPES OF THE GREEN MOUNTAINS AND IN THE SAINT LAWRENCE VALLEY,
AND THIS MAY CAUSE AREAS OF BLOWING SNOW. SNOW SHOWERS WILL
CONTINUE ACROSS THE NORTHERN MOUNTAINS ON FRIDAY AS THE STORM
MOVES AWAY FROM THE REGION. THE WEEKEND WILL BE SEASONABLY COLD,
WITH A CONTINUED CHANCE OF LIGHT SNOW IN THE MOUNTAINS.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
AS OF 906 PM EST WEDNESDAY...EVERYTHING STILL ON TRACK WITH ONLY
MINOR ADJUSTMENTS MADE ONCE AGAIN. COASTAL LOW HAS NOW TAKEN OVER
AND IS LOCATED NEAR SALISBURY MARYLAND AT 994 MB. GREATEST
PRESSURE FALLS ARE ALONG THE NEW JERSEY COASTLINE...CONTINUING TO
SUGGEST A TRACK TOWARDS LONG ISLAND OVERNIGHT. SNOW HAS NOW MADE
IT AS FAR NORTH AS GLENS FALLS NEW YORK...AND WILL CONTINUE ITS
SLOW PROGRESSION NORTHWARD OVER THE NEXT FEW HOURS. HAVE SEEN
WIDESPREAD 1-2" PER HOUR RATES ACROSS NEW YORK...WESTERN
MASSACHUSETTS...AND CONNECTICUT...WITH EVEN SOME 3-4" PER HOUR
RATES IN THE HEAVIEST BANDS. LATEST HRRR CONTINUES TO SHOW THIS
HEAVY BAND MOVING NORTHWARD...WITH HEAVIEST PRECIP 5-8Z IN
SOUTHERN AREAS...7-10Z IN THE CHAMPLAIN VALLEY AND NORTHERN
VERMONT...AND 7-13Z ACROSS NORTHERN NEW YORK. ALSO OF
NOTE...DOWNSLOPE WINDS JUST GETTING GOING IN SOUTHERN
VERMONT...WITH RECENT GUSTS TO 25 KNOTS AT BENNINGTON AND 23 KNOTS
AT RUTLAND.
PREVIOUS DISCUSSION FROM 642 PM EST...
EVERYTHING REMAINS ON TRACK...AND ONLY MINOR ADJUSTMENTS WERE
MADE. HAD TO DROP TEMPERATURES SLIGHTLY THIS EVENING...WITH
WIDESPREAD TEENS ACROSS THE REGION. LOWS WILL BE REACHED OVER THE
NEXT COUPLE OF HOURS...AND THEN SLOWLY RISE OVERNIGHT.
OTHERWISE...TRIED TO NARROW DOWN THE START TIME FOR SNOW ACROSS
THE AREA. PRIMARY LOW NOW LOCATED OVER WEST VIRGINIA WITH A
SECONDARY LOW DEVELOPING NEAR WAKEFIELD VIRGINIA. SECONDARY LOW
WILL TAKE OVER DURING THE REST OF THE EVENING AND PROGRESS TO NEAR
DELAWARE BY 03Z...NEW YORK CITY BY 09Z....AND THEN LONG ISLAND BY
12Z. JUDGING BY CURRENT OBSERVATIONS...SNOW HAS NOW REACHED AS FAR
NORTH AS THE MID-HUDSON VALLEY...THE CENTRAL MOHAWK VALLEY...AND
THE SHORES OF LAKE ONTARIO IN NEW YORK...WITH A SLOW NORTHWARD
PROGRESSION. SHOULD BE INTO THE ADIRONDACKS AND SOUTHERN VERMONT
AROUND 02Z (9 PM)...THE CHAMPLAIN VALLEY AROUND 04Z (11 PM)...AND
THE NORTHEAST KINGDOM AROUND 05Z (MIDNIGHT). HEAVIEST SNOW WITH
INITIAL BAND OF WARM AIR ADVECTION PRECIPITATION WILL LIKELY OCCUR
BETWEEN 07Z AND 10Z (2 AM AND 5 AM) WHERE RATES OF 1-2 INCHES PER
HOUR ARE POSSIBLE...ESPECIALLY IN THE SOUTHEAST- UPSLOPE FAVORED
LOCATIONS. DOWNSLOPE WINDS WILL ALSO BE INCREASING ACROSS THE
SOUTHERN GREENS WITH GUSTS UP TO 40 MPH POSSIBLE IN EASTERN
ADDISON AND RUTLAND COUNTIES BETWEEN 06Z AND 10Z (1 AM AND 5 AM).
THIS WILL CREATE SOME WARMING AND DRYING IN THOSE AREAS...AND
COMBINED WITH SOME WARMING ALOFT (750-800 MB) AS INDICATED BY
LATEST RAP AND NAM...WILL LIKELY SEE SOME SLEET MIX IN ACROSS
RUTLAND AND WINDSOR COUNTIES AFTER 07Z...AND ESPECIALLY AFTER 10Z.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
AS OF 325 PM EST WEDNESDAY...GONNA BE A BUSY DAY THURSDAY. LOTS OF
SNOW. THE STORM WILL TRACK NORTHEAST AND CUT ACROSS CAPE COD (OR
VERY NEAR IT) BY LATE IN THE AFTERNOON. THIS PUTS THE NORTH
COUNTRY INTO A SWEET SPOT FOR THE HEAVIEST QPF. THE DRY SLOT JUST
WONT GET THIS FAR NORTH, AND AS THE LOW MOVES OFF TO THE EAST,
WE`LL BE IN THE PIVOT ZONE INTO THE AFTERNOON.
EXCELLENT DYNAMICS AND SNOW GROWTH MAXED WITH UPWARD MOTION
SHOULD RESULT IN A PERIOD OF HEAVY SNOW MOST EVERYWHERE. THINKING
THE PRIMARY TIME WILL BE 6AM TO NOON, WITH RATES OF 1-2" PER HOUR.
CAN`T RULE OUT LOCALIZED MESOSCALE BAND WITH EVEN A LITTLE BIT
MORE. LIQUID QPF WILL BE QUITE IMPRESSIVE. SPENT A GOOD DEAL OF
TIME TRYING TO ACCOUNT FOR OROGRAPHIC EFFECTS AS WELL. BY THE TIME
WE GET TO THURSDAY NIGHT, MOST OF US WILL SEE ON THE ORDER OF 1 TO
1.5" OF LIQUID EQUIVALENT. SHADOWING WILL MAKE THE NUMBER A LITTLE
LOWER IN THE NORTHEAST KINGDOM AND WESTERN SLOPES OF THE SOUTHERN
GREENS, BUT THEN THAT ON THE FLIP SIDE, ORGRAPHICS WILL HELP ON
THE EASTERN SIDES OF THE GREENS AND DACKS. HAVE INCREASED THE SNOW
TOTALS A FEW INCHES ACROSS THE BOARD -- THINKING 12 TO 17 INCHES,
WITH THE JACKPOT LOCATIONS SEEING ABOUT 20". EVEN THOSE WHO SEE
THE LEAST WILL GET ABOUT 8", WHICH IS NOT SHABBY.
WINDS WILL CONTINUE TO BE GUSTY THE FIRST HALF OF THURSDAY ALONG
THE WESTERN SLOPES. ALSO HAVE TO WATCH FOR STRONG NORTHEAST WINDS
FUNNELLING DOWN THE ST LAWRENCE VALLEY. DONT THINK THEY`LL HIT
WIND ADVISORY CRITERIA, BUT STILL THEY`LL HAVE SUSTAINED WINDS 15
TO 25 MPH WITH HIGHER GUSTS -- AND THAT WILL CAUSE A CONSIDERABLE
AMOUNT OF DRIFTING/BLOWING SNOW OUT THERE. HAVE ADDED THAT WORDING
TO THE FORECAST.
SNOW WILL BEGIN TO TAPER OFF IN THE EVENING, THOUGH LIGHT SNOWS
WILL CONTINUE ALL NIGHT. AS THE LOW PUSHES EAST OF HERE, WINDS
WILL CLOCK AROUND TO NORTHWEST. MOISTURE WILL BE SLOW TO LEAVE, SO
THE NORTHWEST WINDS AND THAT MOISTURE WILL RESULT IN A GOOD AMOUNT
OF OROGRAPHICS, SO THE HIGHER TERRAIN WILL PICK UP A FEW
ADDITIONAL INCHES OF SNOW (AT LEAST) ON FRIDAY.
FINALLY TAPER POPS DOWN TO CHANCE LEVELS BY FRIDAY NIGHT, THOUGH A
WEAK SYSTEM APPROACHING FROM THE WEST MAY SPARK A LITTLE BIT OF
LIGHT SNOW/FLURRIES.
QUICK NOTE ON TEMPERATURES -- PRIMARILY KEPT TO THE COOLER SIDE OF
GUIDANCE FOR THE ENTIRE TIME.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AS OF 342 PM EST WEDNESDAY...OVERALL LITTLE CHANGE FROM PREVIOUS
COUPLE OF FCSTS...WITH BLW NORMAL TEMPS AND PRECIP EXPECTED FOR
DAYS 4 THRU 7. THE EXTENDED FCST CHALLENGE WL BE TIMING/MAGNITUDE
OF ARCTIC AIRMASS ACRS OUR CWA EARLY NEXT WK. WL CONT TO MENTION
LOW CHC POPS FOR LATE SAT INTO SUNDAY ASSOCIATED WITH MID/UPPER
LVL TROF AND SOME 850 TO 500MB RH. LATEST TRENDS HAVE BEEN FOR
LESS RH AND QPF ACRS OUR CWA...BUT ECMWF IS A BIT CLOSER TO THE
COAST WITH SFC LOW PRES AND ENOUGH MOISTURE MAY MOVE BACK INTO OUR
CWA FOR SOME LIGHT SNOW. OTHERWISE...ECMWF/GEM SHOW MID/UPPER LVL
TROF DEVELOPING ACRS EASTERN CANADA WITH A MAINLY DRY NW FLW
ALOFT. HOWEVER...A WELL DEFINED ARCTIC BOUNDARY WL PUSH ACRS OUR
CWA EARLY NEXT WEEK...ALONG WITH A RIBBON OF ENHANCED MOISTURE.
THIS MOISTURE...ALONG WITH SOME ADDITIONAL MOISTURE FROM THE GREAT
LAKES WL HELP IN PRODUCING SOME SNOW SHOWERS ACRS OUR CWA ON
MONDAY INTO TUES. IN ADDITION...MUCH COLDER TEMPS WL ADVECT BACK
INTO OUR CWA FOR NEXT WK. STILL SOME UNCERTAINTY WITH REGARDS TO
TIMING OF THIS FEATURE...AS GFS IS 6 TO 12 HRS SLOWER AND SHOWS
THE COLDEST TEMPS ACRS OUR CWA ON WEDS. TIMING OF BOUNDARY WL MAKE
A HUGE DIFFERENCE IN TEMPS FROM NEAR 30F AT BTV IF THE GFS IS
RIGHT TO LOWER TEENS IF THE ECMWF/GEM ARE CORRECT ON TUES. GIVEN THE
DEVELOPMENT OF A LARGE SCALE TROF AND DEEP CYCLONIC FLW ACRS THE
NE CONUS...WL TREND TWD THE COLDER ECMWF/GEM FOR NEXT WEEK...AND
MENTION HIGHS ONLY IN THE TEENS/L20S WITH LOWS MAINLY IN THE
SINGLE DIGITS/LOWER TEENS. IF SFC HIGH PRES BUILDS INTO THE
REGION...FASTER THAN PROGGED...THEN WINDS WL DECREASE AND
OVERNIGHT LOWS WL NEED TO BE ADJUSTED DOWN BY 5 TO 10 DEGREES. ITS
ALWAYS DIFFICULT TO DETERMINE AMOUNT OF CAA AND IMPACTS ACRS OUR
CWA IN THE DAY 5 TO 7 RANGE. TODAY IS A GREAT EXAMPLE OF TRYING TO
PREDICT THE COLD AIR...AS TEMPS STRUGGLED MAINLY IN THE TEENS.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
THROUGH 00Z FRIDAY...SNOW TO MOVE IN TO ALL TAF SITES 03-05Z,
LOWERING CONDITIONS TO LIFR TO IFR FOR ALL OF TAF PERIOD. HEAVIER BURSTS
POSSIBLE 09-14Z AT HEIGHT OF STORM. AFTER 14Z WILL BEGIN TO SEE
SLOW IMPROVEMENT...BUT STILL IFR. POTENTIAL FOR LAYER OF NEAR TO
ABOVE FREEZING AIR TO MOVE IN TO SOUTHERN VERMONT 10-15Z...AND
PRODUCE SLEET AT KRUT. TEMPERATURE PROFILE RIGHT ON THE EDGE...AND
COULD EASILY STAY ALL SNOW IF TEMPERATURES REMAIN COOL ENOUGH.
EAST TO SOUTHEAST LOW LEVEL JET TO MOVE INTO AREA OVERNIGHT...WITH
KRUT LIKELY TO EXPERIENCE STRONGEST WIND GUSTS 20-35 KTS. VALLEY
CHANNELING AT KMSS WILL PRODUCE GUSTS TO 20-25 KTS. ELSEWHERE
STRONGER WINDS LESS FAVORABLE... REMAINING SITES STILL TO SEE
15-20 KTS.
OUTLOOK 00Z FRIDAY THROUGH MONDAY...
00Z FRIDAY-00Z SATURDAY...LOW WILL MOVE INTO THE GULF OF
MAINE...SHIFTING SURFACE WINDS TO NORTHWEST. SNOW SHOWERS TO
CONTINUE ESPECIALLY IN FAVORED UPSLOPE AREAS...AND HIGHER
ELEVATION SITES KMPV/KSLK LIKELY WILL SEE CONTINUED MVFR TO IFR
CIG/VIS. MOSTLY VFR ELSEWHERE...ALTHOUGH FRESH SNOW AND GUSTY
WINDS WILL PRODUCE SOME BLOWING/DRIFTING.
00Z SATURDAY THROUGH 00Z SUNDAY...SFC HIGH PRES SLOWLY BUILDS INTO
OUR TAF SITES BY 12Z SATURDAY. SOME LEFTOVER MTN SNOW SHOWERS AT
MPV/SLK WL CREATE OCCASIONAL MVFR CONDITIONS THRU 06Z SAT...BEFORE
DISSIPATING WITH VFR CONDITIONS DEVELOPING AFT 06Z SATURDAY.
00Z SUNDAY THROUGH MONDAY...MAINLY VFR CONDITIONS WITH A CHANCE OF
MVFR SNOW SHOWERS ACROSS CENTRAL AND SOUTHERN AREAS SATURDAY NIGHT
AS LOW PRESSURE MOVES EAST ACROSS THE MID-ATLANTIC STATES.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...WINTER STORM WARNING UNTIL 7 AM EST FRIDAY FOR VTZ001>012-
016>019.
NY...WINTER STORM WARNING UNTIL 7 AM EST FRIDAY FOR NYZ026>031-034-
035-087.
&&
$$
SYNOPSIS...NASH
NEAR TERM...MUCCILLI
SHORT TERM...NASH
LONG TERM...TABER
AVIATION...HANSON
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
830 PM EST WED DEC 26 2012
.SYNOPSIS...
A STRONG WINTER STORM WILL IMPACT THE AREA TONIGHT LEADING TO
HEAVY SNOW ACCUMULATIONS ACROSS THE ENTIRE FORECAST AREA. WRAP
AROUND MOISTURE WILL THEN RESULT IN CONTINUED SNOWS FOR MUCH OF
CENTRAL NEW YORK ON THURSDAY BEFORE HIGH PRESSURE SLOWLY BUILDS
INTO THE AREA TOWARDS THE CONCLUSION OF THE WEEK.
&&
.NEAR TERM /THROUGH THURSDAY/...
8 PM UPDATE... RADAR/SAT LOOPS SHOW A WELL DEFINED DRY SLOT
HEADING NWD THROUGH ERN PA ATTM. THE LATEST RAPID REFRESH
MODEL RUNS...AND ALSO THE 18Z NWP GUIDANCE SHOW THIS FEATURE...BUT
HAVE NOT QUITE CAUGHT ON TO ITS QUICK NWD MOVEMENT. THUS...WE`VE SPED
UP THE TRANSITION FROM STEADY HVY SNOW...TO LGTR SNOW...OR A LGT
MIX...GENERALLY OCCURRING FROM 00-03Z...ALG AND JUST E OF THE I-81
CORRIDOR.
ALSO...THE CHARACTER OF THE RADAR ECHOES...PLUS
PLENTIFUL SPOTTER/PUBLIC REPORTS...SHOW A HODGE-PODGE OF
SNOW...SLEET...FZRA BASICALLY ALG AND S OF ROUTE 6 IN NRN PA ATTM.
THIS AREA OF MIXED PCPN WILL PROBABLY EXTEND TO ABT THE I-88
CORRIDOR IN SRN NY TWDS 03-04Z...BUT WE DON`T EXPECT IT TO MOVE
ANY FARTHER TO THE N OR W.
AT THIS JUNCTURE...WE DON`T SEE A LOT OF EVIDENCE THAT THE ERLY
FLOW/TERRAIN INDUCED PCPN SHADOWING...CONSISTENTLY SHOWN BY MANY
OF OUR HI-RES MODELS FOR THIS EVE...HAS DVLPD...OR WILL DVLP.
WE`LL SEE HOW THE DRY SLOT ADVANCING ACRS PA DVLPS LTR THIS
EVE...IN THIS REGARD.
BOTTOM LN...WE`RE NOT MAKING ANY SUBSTANTIVE CHGS TO OUR SNOW
TOTALS. INITIAL BURST OF VERY HVY SNOW IN OUR FAR SRN ZNS IN THE MID TO
LATE AFTN HRS...HAVE BROUGHT SNOW TOTALS INTO THE 3-6" RANGE ATTM.
GIVEN MIXED PCPN THESE AREAS CURRENTLY...TOTALS WILL LIKELY NOT GO
A GREAT DEAL HIGHER. ACRS THE TWIN TIERS...VERY HVY SNOW THE LAST
SVRL HRS...IS LIKELY TO SLOW DOWN A BIT THROUGH ABT
06Z...ESPECIALLY S AND E OF A TOWANDA TO KBGM TO ONEONTA LN. SNOW
TOTALS HAVE RANGED FROM 4-8" IN MANY LOCALES THROUGHOUT THESE
AREAS SO FAR.
FOR MANY OF OUR NRN AND WRN ZNS...HVY SNOW BANDS WILL CONTINUE TO
ROTATE ACRS THROUGH AT LEAST 06Z...AS MID-LVL FGEN MAXIMIZES...AND
THETA-E LR`S ALOFT DECREASE ON THE LEADING EDGE OF THE DRY SLOT.
ISOLD THUNDER-SNOW NOT OUT OF THE QUESTION...AND IN FACT...SOME
OF THIS HAS ALREADY BEEN REPORTED IN CHENANGO CNTY. STORM TOTALS
OF A FOOT OR MORE WILL BE MOST PROBABLE THESE PTNS OF THE FA.
OVERALL...ONLY MINOR TWEAKS MADE...TO BEST REFLECT THE LATEST
RADAR/TEMP TRENDS. NEAR-TERM SPS`S AND FREQUENT WSW UPDATES WILL
CONTINUE TO BE ISSUED.
PREV DISC... CONDITIONS RAPIDLY DETERIORATING ACROSS THE AREA THIS
AFTERNOON AS LONG ADVERTISED WINTER STORM GETS UNDERWAY. REGIONAL
WATER VAPOR IMAGERY SHOWING MAIN MID-LEVEL CIRCULATION SLIDING
ACROSS THE EASTERN TN/KY BORDER THIS AFTERNOON...WITH NOTABLE DRY
SLOT BEGINNING TO WORK NORTH TOWARDS PIT AS SYSTEM CONTINUES THE
OCCLUSION PROCESS. LATEST RUC TROP PRESSURE FIELD SHOWS MAIN WAVE
NOW TAKING ON A NEGATIVE TILT WHICH SUGGEST UPPER FEATURE IS
REACHING MATURITY. MEANWHILE ALONG THE SURFACE...SECONDARY LOW
PRESSURE DEVELOPMENT NOW TAKING SHAPE ACROSS THE NORTH CAROLINA
PIEDMONT REGION...WITH SFC PRESSURE FIELDS REVEALING A NOTABLE
COLD AIR DAMMING SIGNATURE ALONG THE EASTERN SPIN OF THE
APPALACHIANS. IF NOTHING LESS...THE PRESENCE OF THIS SIGNATURE
WILL HELP ENSURE CONDITIONS ARE PRE-CONDITIONED FOR A ROUND OF
HEAVY SNOWFALL ACROSS THE FCST AREA TONIGHT AS WARM AIR ADVECTION
FORCING INCREASES IN ADVANCE OF THE SECONDARY LOW PRESSURE
SYSTEM/S MOVEMENT UP THE EAST COAST.
THE ABOVE SAID...LATEST RADAR TRENDS SHOWING SNOW MAKING STEADY
PROGRESS NORTHWARD THIS AFTERNOON WITH SNOW ALREADY BEING
REPORTED AT BOTH ELM AND AVP. QUICK INSPECTION OF RUC LAYERED
THETA-E LAPSE RATES SUGGEST A FAIR AMOUNT OF CONDITIONAL
INSTABILITY EXISTS ALOFT WHICH WILL LEAD TO SNOWFALL RATES ON THE
ORDER OF 2-3`/HR UNDER THE HEAVIEST ACTIVITY. DESPITE THE FACT THE
STORM IS ALREADY ONGOING ACROSS THE AREA...A FAIR AMOUNT OF MODEL
UNCERTAINTY STILL EXISTS WITH EXPECTED CONDITIONS OVERNIGHT AS THE
SECONDARY LOW PASSES TO OUR SOUTH AND EAST. WHAT DOES APPEAR FOR
CERTAIN IS THAT THE HEAVIEST SNOWFALL WILL OCCUR BETWEEN NOW AND
06Z AS THE MAIN AREA OF FRONTOGENESIS AND WARM AIR ADVECTION
FORCING LIFTS THROUGH THE FCST AREA. UNFORTUNATELY THIS WILL OCCUR
DURING THE AFTERNOON COMMUTE WHICH WILL UNDOUBTEDLY MAKE THINGS
DICEY FOR THOSE HEADING HOME THIS EVENING. MODELS CONTINUE TO
INSIST ON THE PREVIOUSLY MENTIONED DRY SLOT MOVING NORTH INTO OUR
AREA AFTER 06Z WHICH WILL LEAD TO A FAIR AMOUNT OF DRYING WITHIN
THE DENDRITIC SNOW GROWTH REGION. AS A RESULT...WE EXPECT TO SEE
THE HEAVY SNOW ZONE GRADUALLY ROTATE TO THE WEST WITH TIME AS A
POORLY DEFINED DEFORMATION AXIS ATTEMPTS TO FORM AFTER 06Z.
FURTHER TO THE EAST...PRONOUNCED DRY AIR ALOFT WILL LIKELY LEAD TO
A GRADUAL DECREASE IN SNOWFALL INTENSITY FOR THE SUSQUEHANNA
VALLEY REGION OF CENTRAL NY AND POINTS SOUTH TO INCLUDE THE TWIN
TIERS...POCONOS...AND LOWER WYOMING VALLEY. DESPITE THE PRESENCE
OF THE DRY SLOT...FORECAST MODELS CONTINUE TO PRODUCE LIGHT QPF
ACROSS THESE REGIONS WHICH LEADS US TO BELIEVE THAT FREEZING RAIN
AND PERHAPS SOME SLEET WILL BEGIN FOR THESE AREAS TOWARDS THE
EARLY MORNING HRS. IF THIS WERE TO OCCUR AS ADVERTISED...A FAIRLY
HEALTHY ICING EVENT MAY HAPPEN FOR THOSE LOCATIONS. FOR NOW WE
EXPECT THE HEAVIEST ICING TO OCCUR ACROSS THE WYOMING VALLEY AND
SOUTHERN POCONOS WHERE A QUARTER INCH OR MORE OF ICE WILL BE POSSIBLE.
ANOTHER INTRIGUING ASPECT OF THIS STORM IS THAT ALL MODELS TO
INCLUDE THE LOWER RESOLUTION ECMWF SHOW A SHADOWING EFFECT JUST
WEST OF THE CATSKILLS AFTER 06Z THIS EVENING. THIS SEEMS PLAUSIBLE
TO SOME DEGREE AS A STRONG EASTERLY LOW-LEVEL JET OF 70+KTS
IMPINGES ON THE MOUNTAIN RANGE. FOR NOREASTER TYPE EVENTS THIS
SEEMS VERY UNUSUAL HOWEVER WITH ALL SHORT TERM MODEL PROGS
CONTINUING TO INSIST THIS WILL OCCUR...HAVE ELECTED TO LOWER
SNOWFALL TOTALS ACROSS THE WESTERN CATSKILLS JUST A TAD.
SO TO SUM THINGS UP...THE HEAVIEST SNOWS ARE EXPECTED FROM THE
CHEMUNG RVR VLY NORTHEAST TROUGH THE FINGER LAKES AND WESTERN
MOHAWK VALLEY. ACROSS THESE LOCATIONS...ANYWHERE BETWEEN 10-14"
WILL BE POSSIBLE. FURTHER SOUTH AND EAST...8-10" ARE FORECAST
ACROSS THE TWIN TIERS AND WESTERN CATSKILLS...WITH 4-6" EXPECTED
FOR THE SOUTHERN CATSKILLS...POCONOS AND LOWER WYOMING VLY. NO
CHANGES MADE TO INHERITED HAZARDS WITH THE EXCEPTION OF BEEFING UP
THE WORDING FOR POTENTIAL ICE ACCUMULATIONS ACROSS THE SOUTH.
FOR THURSDAY...EXPECT SOME LINGERING WRAP AROUND MOISTURE TO LEAD
TO CONTINUED SNOW ACROSS PORTIONS OF UPSTATE NY. H85 TEMPS LOOK A
TAD TOO WARM TO RESULT IN ANY SIGNIFICANT LAKE ENHANCEMENT. WILL
CONTINUE TO CARRY LIKELY POPS ACROSS THE NORTH WITH SLGT CHC-CHC
TO THE SOUTH.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY/...
STORM MOVES AWAY FROM THE AREA THURSDAY NIGHT. EXPECT SOME LIGHT
LAKE EFFECT SNOW SOUTH-SOUTHEAST OF LAKE ONTARIO WITH A 320 TO 325
DEGREE FLOW AND SOME LINGERING MOISTURE. HOWEVER WITH MARGINAL
TEMPERATURES AROUND -8 TO -10 DEGREES C AT 850 MB AND INVERSION HGTS
GENERALLY BELOW 5000 FEET EXPECT ONLY LIGHT ACCUMULATIONS... MAYBE
AROUND 2 INCHES ACROSS CENTRAL NY DOWN THROUGH AREAS SOUTHEAST OF
THE FINGER LAKES. DRYING MOVES IN WITH A WEAK RIDGE OF HIGH PRESSURE
ON FRIDAY PUTTING AN END TO ANY LINGERING LIGHT SNOW SHOWERS OR
FLURRIES DURING THE DAY.
NEXT SYSTEM APPROACHES THE AREA LATER FRIDAY NIGHT INTO SATURDAY.
MODEL CONSENSUS WITH THIS NEXT SYSTEM INDICATES A WEAK INVERTED
SURFACE TROUGH TRACKING ACROSS THE AREA WITH SOME LIGHT SNOW... BUT
SIGNIFICANT DEVELOPMENT OF THE SURFACE LOW DOES NOT OCCUR UNTIL THE
STORM IS WELL EAST OF THE MID-ATLANTIC COAST. THEREFORE HEAVY SNOW
DOES NOT APPEAR LIKELY AT THIS TIME.
.LONG TERM /SUNDAY THROUGH TUESDAY...
GFS AND ECMWF ARE IN REASONABLY GOOD AGREEMENT WITH THE OVERALL
PATTERN DURING THIS PERIOD INDICATING NORTHWEST FLOW WITH A SERIES
OF WEAKLY ORGANIZED CLIPPER SYSTEMS LIKELY ALONG WITH SOME LAKE EFFECT
SNOW. HOWEVER AT THIS POINT THERE IS NO INDICATION FOR ANY MAJOR
SYNOPTIC SCALE SYSTEMS THAT WOULD TAP GULF MOISTURE. TIMING OF THESE
INDIVIDUAL SYSTEMS WILL BE DIFFICULT BEYOND SUNDAY... BUT RIGHT NOW
THE BEST CHC FOR A WEAKLY ORGANIZED CLIPPER-LIKE SYSTEM COULD BE NEW
YEAR`S EVE INTO NEW YEAR`S DAY... WHICH WOULD BE FOLLOWED BY AN
ENHANCED PERIOD OF LAKE EFFECT SNOW. TEMPERATURES THROUGH THE PERIOD
WILL AVERAGE NEAR TO BELOW NORMAL... WITH HIGHS MAINLY IN THE MID
20S TO LOWER 30S AND LOWS IN THE TEENS. HAVE GONE WITH HPC GUIDANCE
THROUGH THE PERIOD INDICATING BEST CHANCES FOR SNOW WILL BE OVER
CENTRAL NY WITH SMALLER CHANCES TOWARD NORTHEAST PA.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
GFS AND ECMWF ARE IN REASONABLY GOOD AGREEMENT WITH THE OVERALL
PATTERN DURING THIS PERIOD INDICATING NORTHWEST FLOW WITH A SERIES
OF WEAKLY ORGANIZED CLIPPER SYSTEMS LIKELY ALONG WITH SOME LAKE EFFECT
SNOW. HOWEVER AT THIS POINT THERE IS NO INDICATION FOR ANY MAJOR
SYNOPTIC SCALE SYSTEMS THAT WOULD TAP GULF MOISTURE. TIMING OF THESE
INDIVIDUAL SYSTEMS WILL BE DIFFICULT BEYOND SUNDAY... BUT RIGHT NOW
THE BEST CHC FOR A WEAKLY ORGANIZED CLIPPER-LIKE SYSTEM COULD BE NEW
YEAR`S EVE INTO NEW YEAR`S DAY... WHICH WOULD BE FOLLOWED BY AN
ENHANCED PERIOD OF LAKE EFFECT SNOW. TEMPERATURES THROUGH THE PERIOD
WILL AVERAGE NEAR TO BELOW NORMAL... WITH HIGHS MAINLY IN THE MID
20S TO LOWER 30S AND LOWS IN THE TEENS. HAVE GONE WITH HPC GUIDANCE
THROUGH THE PERIOD INDICATING BEST CHANCES FOR SNOW WILL BE OVER
CENTRAL NY WITH SMALLER CHANCES TOWARD NORTHEAST PA.
&&
.AVIATION /01Z THURSDAY THROUGH MONDAY/...
IFR THROUGH 18Z THURSDAY DUE TO STRONG STORM SYSTEM AFFECTING THE AREA.
VSBYS WILL RANGE FROM 1/2 TO 2 MILES THROUGH THE OVERNIGHT PERIOD
OCCASIONALLY DROPPING TO 1/4SM. LIGHT TO MODERATE SNOW WILL
CONTINUE THROUGH NY TERMINALS WITH KAVP BECOMING MIXED
PRECIPITATION IN THE NEXT 1-2 HOURS AND LIGHTENING UP, EVENTUALLY
RISING TO MVFR AFTER 05Z. SNOW WILL BEGIN TO BECOME LIGHTER AFTER
05Z BUT STILL REMAIN AROUND IFR.
SNOW WILL BECOME SHOWERY DURING THE DAY THURSDAY WITH MVFR TO OCNL
IFR CONDITIONS PERSISTING THROUGH THE DAY IN CENTRAL NY. MVFR TO
OCNL VFR CONDITIONS CAN BE EXPECTED AT AVP WITH LIGHT SNOW
SHOWERS DURING THE AFTERNOON.
WINDS WILL BE E-NE AROUND 10-20 KTS TONIGHT THEN SHIFTING TO NW AT 10
TO 20 KTS WITH OCCASIONAL GUSTS TO 25 KTS ON THURSDAY.
OUTLOOK...
THUR NGT...MVFR/IFR IN SNOW SHOWERS ESPECIALLY OVER CENTRAL NY.
FRI...MAINLY VFR...MVFR/IFR POSSIBLE NORTHERN TERMINALS IN LAKE
EFFECT SNOW.
SAT...ANOTHER POSSIBLE WINTER SYSTEM AND THUS POSSIBLE IFR/MVFR.
SUN...MVFR/IFR POSSIBLE AT FOR CNY TERMINALS IN DEVELOPING LAKE
EFFECT SN.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...WINTER STORM WARNING UNTIL 1 PM EST THURSDAY FOR PAZ038>040-
043-044-047-048-072.
NY...WINTER STORM WARNING UNTIL 1 PM EST THURSDAY FOR NYZ009-
015>018-022>025-036-037-044>046-055>057-062.
&&
$$
SYNOPSIS...CMG
NEAR TERM...CMG/MLJ
SHORT TERM...DGM
LONG TERM...PVN
AVIATION...PVN
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
701 PM EST WED DEC 26 2012
.SYNOPSIS...
A STRONG WINTER STORM WILL IMPACT THE AREA TONIGHT LEADING TO
HEAVY SNOW ACCUMULATIONS ACROSS THE ENTIRE FORECAST AREA. WRAP
AROUND MOISTURE WILL THEN RESULT IN CONTINUED SNOWS FOR MUCH OF
CENTRAL NEW YORK ON THURSDAY BEFORE HIGH PRESSURE SLOWLY BUILDS
INTO THE AREA TOWARDS THE CONCLUSION OF THE WEEK.
&&
.NEAR TERM /THROUGH THURSDAY/...
CONDITIONS RAPIDLY DETERIORATING ACROSS THE AREA THIS AFTERNOON AS
LONG ADVERTISED WINTER STORM GETS UNDERWAY. REGIONAL WATER VAPOR
IMAGERY SHOWING MAIN MID-LEVEL CIRCULATION SLIDING ACROSS THE
EASTERN TN/KY BORDER THIS AFTERNOON...WITH NOTABLE DRY SLOT
BEGINNING TO WORK NORTH TOWARDS PIT AS SYSTEM CONTINUES THE
OCCLUSION PROCESS. LATEST RUC TROP PRESSURE FIELD SHOWS MAIN WAVE
NOW TAKING ON A NEGATIVE TILT WHICH SUGGEST UPPER FEATURE IS
REACHING MATURITY. MEANWHILE ALONG THE SURFACE...SECONDARY LOW
PRESSURE DEVELOPMENT NOW TAKING SHAPE ACROSS THE NORTH CAROLINA
PIEDMONT REGION...WITH SFC PRESSURE FIELDS REVEALING A NOTABLE
COLD AIR DAMMING SIGNATURE ALONG THE EASTERN SPIN OF THE
APPALACHIANS. IF NOTHING LESS...THE PRESENCE OF THIS SIGNATURE
WILL HELP ENSURE CONDITIONS ARE PRE-CONDITIONED FOR A ROUND OF
HEAVY SNOWFALL ACROSS THE FCST AREA TONIGHT AS WARM AIR ADVECTION
FORCING INCREASES IN ADVANCE OF THE SECONDARY LOW PRESSURE
SYSTEM/S MOVEMENT UP THE EAST COAST.
THE ABOVE SAID...LATEST RADAR TRENDS SHOWING SNOW MAKING STEADY
PROGRESS NORTHWARD THIS AFTERNOON WITH SNOW ALREADY BEING
REPORTED AT BOTH ELM AND AVP. QUICK INSPECTION OF RUC LAYERED
THETA-E LAPSE RATES SUGGEST A FAIR AMOUNT OF CONDITIONAL
INSTABILITY EXISTS ALOFT WHICH WILL LEAD TO SNOWFALL RATES ON THE
ORDER OF 2-3`/HR UNDER THE HEAVIEST ACTIVITY. DESPITE THE FACT THE
STORM IS ALREADY ONGOING ACROSS THE AREA...A FAIR AMOUNT OF MODEL
UNCERTAINTY STILL EXISTS WITH EXPECTED CONDITIONS OVERNIGHT AS THE
SECONDARY LOW PASSES TO OUR SOUTH AND EAST. WHAT DOES APPEAR FOR
CERTAIN IS THAT THE HEAVIEST SNOWFALL WILL OCCUR BETWEEN NOW AND
06Z AS THE MAIN AREA OF FRONTOGENESIS AND WARM AIR ADVECTION
FORCING LIFTS THROUGH THE FCST AREA. UNFORTUNATELY THIS WILL OCCUR
DURING THE AFTERNOON COMMUTE WHICH WILL UNDOUBTEDLY MAKE THINGS
DICEY FOR THOSE HEADING HOME THIS EVENING. MODELS CONTINUE TO
INSIST ON THE PREVIOUSLY MENTIONED DRY SLOT MOVING NORTH INTO OUR
AREA AFTER 06Z WHICH WILL LEAD TO A FAIR AMOUNT OF DRYING WITHIN
THE DENDRITIC SNOW GROWTH REGION. AS A RESULT...WE EXPECT TO SEE
THE HEAVY SNOW ZONE GRADUALLY ROTATE TO THE WEST WITH TIME AS A
POORLY DEFINED DEFORMATION AXIS ATTEMPTS TO FORM AFTER 06Z.
FURTHER TO THE EAST...PRONOUNCED DRY AIR ALOFT WILL LIKELY LEAD TO
A GRADUAL DECREASE IN SNOWFALL INTENSITY FOR THE SUSQUEHANNA
VALLEY REGION OF CENTRAL NY AND POINTS SOUTH TO INCLUDE THE TWIN
TIERS...POCONOS...AND LOWER WYOMING VALLEY. DESPITE THE PRESENCE
OF THE DRY SLOT...FORECAST MODELS CONTINUE TO PRODUCE LIGHT QPF
ACROSS THESE REGIONS WHICH LEADS US TO BELIEVE THAT FREEZING RAIN
AND PERHAPS SOME SLEET WILL BEGIN FOR THESE AREAS TOWARDS THE
EARLY MORNING HRS. IF THIS WERE TO OCCUR AS ADVERTISED...A FAIRLY
HEALTHY ICING EVENT MAY HAPPEN FOR THOSE LOCATIONS. FOR NOW WE
EXPECT THE HEAVIEST ICING TO OCCUR ACROSS THE WYOMING VALLEY AND
SOUTHERN POCONOS WHERE A QUARTER INCH OR MORE OF ICE WILL BE POSSIBLE.
ANOTHER INTRIGUING ASPECT OF THIS STORM IS THAT ALL MODELS TO
INCLUDE THE LOWER RESOLUTION ECMWF SHOW A SHADOWING EFFECT JUST
WEST OF THE CATSKILLS AFTER 06Z THIS EVENING. THIS SEEMS PLAUSIBLE
TO SOME DEGREE AS A STRONG EASTERLY LOW-LEVEL JET OF 70+KTS
IMPINGES ON THE MOUNTAIN RANGE. FOR NOREASTER TYPE EVENTS THIS
SEEMS VERY UNUSUAL HOWEVER WITH ALL SHORT TERM MODEL PROGS
CONTINUING TO INSIST THIS WILL OCCUR...HAVE ELECTED TO LOWER
SNOWFALL TOTALS ACROSS THE WESTERN CATSKILLS JUST A TAD.
SO TO SUM THINGS UP...THE HEAVIEST SNOWS ARE EXPECTED FROM THE
CHEMUNG RVR VLY NORTHEAST TROUGH THE FINGER LAKES AND WESTERN
MOHAWK VALLEY. ACROSS THESE LOCATIONS...ANYWHERE BETWEEN 10-14"
WILL BE POSSIBLE. FURTHER SOUTH AND EAST...8-10" ARE FORECAST
ACROSS THE TWIN TIERS AND WESTERN CATSKILLS...WITH 4-6" EXPECTED
FOR THE SOUTHERN CATSKILLS...POCONOS AND LOWER WYOMING VLY. NO
CHANGES MADE TO INHERITED HAZARDS WITH THE EXCEPTION OF BEEFING UP
THE WORDING FOR POTENTIAL ICE ACCUMULATIONS ACROSS THE SOUTH.
FOR THURSDAY...EXPECT SOME LINGERING WRAP AROUND MOISTURE TO LEAD
TO CONTINUED SNOW ACROSS PORTIONS OF UPSTATE NY. H85 TEMPS LOOK A
TAD TOO WARM TO RESULT IN ANY SIGNIFICANT LAKE ENHANCEMENT. WILL
CONTINUE TO CARRY LIKELY POPS ACROSS THE NORTH WITH SLGT CHC-CHC
TO THE SOUTH.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY/...
STORM MOVES AWAY FROM THE AREA THURSDAY NIGHT. EXPECT SOME LIGHT
LAKE EFFECT SNOW SOUTH-SOUTHEAST OF LAKE ONTARIO WITH A 320 TO 325
DEGREE FLOW AND SOME LINGERING MOISTURE. HOWEVER WITH MARGINAL
TEMPERATURES AROUND -8 TO -10 DEGREES C AT 850 MB AND INVERSION HGTS
GENERALLY BELOW 5000 FEET EXPECT ONLY LIGHT ACCUMULATIONS... MAYBE
AROUND 2 INCHES ACROSS CENTRAL NY DOWN THROUGH AREAS SOUTHEAST OF
THE FINGER LAKES. DRYING MOVES IN WITH A WEAK RIDGE OF HIGH PRESSURE
ON FRIDAY PUTTING AN END TO ANY LINGERING LIGHT SNOW SHOWERS OR
FLURRIES DURING THE DAY.
NEXT SYSTEM APPROACHES THE AREA LATER FRIDAY NIGHT INTO SATURDAY.
MODEL CONSENSUS WITH THIS NEXT SYSTEM INDICATES A WEAK INVERTED
SURFACE TROUGH TRACKING ACROSS THE AREA WITH SOME LIGHT SNOW... BUT
SIGNIFICANT DEVELOPMENT OF THE SURFACE LOW DOES NOT OCCUR UNTIL THE
STORM IS WELL EAST OF THE MID-ATLANTIC COAST. THEREFORE HEAVY SNOW
DOES NOT APPEAR LIKELY AT THIS TIME.
.LONG TERM /SUNDAY THROUGH TUESDAY...
GFS AND ECMWF ARE IN REASONABLY GOOD AGREEMENT WITH THE OVERALL
PATTERN DURING THIS PERIOD INDICATING NORTHWEST FLOW WITH A SERIES
OF WEAKLY ORGANIZED CLIPPER SYSTEMS LIKELY ALONG WITH SOME LAKE EFFECT
SNOW. HOWEVER AT THIS POINT THERE IS NO INDICATION FOR ANY MAJOR
SYNOPTIC SCALE SYSTEMS THAT WOULD TAP GULF MOISTURE. TIMING OF THESE
INDIVIDUAL SYSTEMS WILL BE DIFFICULT BEYOND SUNDAY... BUT RIGHT NOW
THE BEST CHC FOR A WEAKLY ORGANIZED CLIPPER-LIKE SYSTEM COULD BE NEW
YEAR`S EVE INTO NEW YEAR`S DAY... WHICH WOULD BE FOLLOWED BY AN
ENHANCED PERIOD OF LAKE EFFECT SNOW. TEMPERATURES THROUGH THE PERIOD
WILL AVERAGE NEAR TO BELOW NORMAL... WITH HIGHS MAINLY IN THE MID
20S TO LOWER 30S AND LOWS IN THE TEENS. HAVE GONE WITH HPC GUIDANCE
THROUGH THE PERIOD INDICATING BEST CHANCES FOR SNOW WILL BE OVER
CENTRAL NY WITH SMALLER CHANCES TOWARD NORTHEAST PA.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
GFS AND ECMWF ARE IN REASONABLY GOOD AGREEMENT WITH THE OVERALL
PATTERN DURING THIS PERIOD INDICATING NORTHWEST FLOW WITH A SERIES
OF WEAKLY ORGANIZED CLIPPER SYSTEMS LIKELY ALONG WITH SOME LAKE EFFECT
SNOW. HOWEVER AT THIS POINT THERE IS NO INDICATION FOR ANY MAJOR
SYNOPTIC SCALE SYSTEMS THAT WOULD TAP GULF MOISTURE. TIMING OF THESE
INDIVIDUAL SYSTEMS WILL BE DIFFICULT BEYOND SUNDAY... BUT RIGHT NOW
THE BEST CHC FOR A WEAKLY ORGANIZED CLIPPER-LIKE SYSTEM COULD BE NEW
YEAR`S EVE INTO NEW YEAR`S DAY... WHICH WOULD BE FOLLOWED BY AN
ENHANCED PERIOD OF LAKE EFFECT SNOW. TEMPERATURES THROUGH THE PERIOD
WILL AVERAGE NEAR TO BELOW NORMAL... WITH HIGHS MAINLY IN THE MID
20S TO LOWER 30S AND LOWS IN THE TEENS. HAVE GONE WITH HPC GUIDANCE
THROUGH THE PERIOD INDICATING BEST CHANCES FOR SNOW WILL BE OVER
CENTRAL NY WITH SMALLER CHANCES TOWARD NORTHEAST PA.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
IFR THROUGH 18Z THURSDAY DUE TO STRONG STORM SYSTEM AFFECTING THE AREA.
VSBYS WILL RANGE FROM 1/2 TO 2 MILES THROUGH THE OVERNIGHT PERIOD
OCCASIONALLY DROPPING TO 1/4SM. LIGHT TO MODERATE SNOW WILL
CONTINUE THROUGH NY TERMINALS WITH KAVP BECOMING MIXED
PRECIPITATION IN THE NEXT 1-2 HOURS AND LIGHTENING UP, EVENTUALLY
RISING TO MVFR AFTER 05Z. SNOW WILL BEGIN TO BECOME LIGHTER AFTER
05Z BUT STILL REMAIN AROUND IFR.
SNOW WILL BECOME SHOWERY DURING THE DAY THURSDAY WITH MVFR TO OCNL
IFR CONDITIONS PERSISTING THROUGH THE DAY IN CENTRAL NY. MVFR TO
OCNL VFR CONDITIONS CAN BE EXPECTED AT AVP WITH LIGHT SNOW
SHOWERS DURING THE AFTERNOON.
WINDS WILL BE E-NE AROUND 10-20 KTS TONIGHT THEN SHIFTING TO NW AT 10
TO 20 KTS WITH OCCASIONAL GUSTS TO 25 KTS ON THURSDAY.
OUTLOOK...
THUR NGT...MVFR/IFR IN SNOW SHOWERS ESPECIALLY OVER CENTRAL NY.
FRI...MAINLY VFR...MVFR/IFR POSSIBLE NORTHERN TERMINALS IN LAKE
EFFECT SNOW.
SAT...ANOTHER POSSIBLE WINTER SYSTEM AND THUS POSSIBLE IFR/MVFR.
SUN...MVFR/IFR POSSIBLE AT FOR CNY TERMINALS IN DEVELOPING LAKE
EFFECT SN.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...WINTER STORM WARNING UNTIL 1 PM EST THURSDAY FOR PAZ038>040-
043-044-047-048-072.
NY...WINTER STORM WARNING UNTIL 1 PM EST THURSDAY FOR NYZ009-
015>018-022>025-036-037-044>046-055>057-062.
&&
$$
SYNOPSIS...CMG
NEAR TERM...CMG
SHORT TERM...DGM
LONG TERM...PVN
AVIATION...PVN
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
654 PM EST WED DEC 26 2012
.SYNOPSIS...
A POTENT WINTER STORM WILL IMPACT THE ENTIRE REGION TONIGHT
THROUGH THURSDAY NIGHT PRODUCING WIDESPREAD HEAVY SNOWS WITH
AMOUNTS OVER A FOOT. GUSTY WINDS WILL ALSO OCCUR ALONG THE WESTERN
SLOPES OF THE GREEN MOUNTAINS AND IN THE SAINT LAWRENCE VALLEY,
AND THIS MAY CAUSE AREAS OF BLOWING SNOW. SNOW SHOWERS WILL
CONTINUE ACROSS THE NORTHERN MOUNTAINS ON FRIDAY AS THE STORM
MOVES AWAY FROM THE REGION. THE WEEKEND WILL BE SEASONABLY COLD,
WITH A CONTINUED CHANCE OF LIGHT SNOW IN THE MOUNTAINS.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
AS OF 642 PM EST WEDNESDAY...EVERYTHING REMAINS ON TRACK...AND
ONLY MINOR ADJUSTMENTS WERE MADE. HAD TO DROP TEMPERATURES
SLIGHTLY THIS EVENING...WITH WIDESPREAD TEENS ACROSS THE REGION.
LOWS WILL BE REACHED OVER THE NEXT COUPLE OF HOURS...AND THEN
SLOWLY RISE OVERNIGHT. OTHERWISE...TRIED TO NARROW DOWN THE START
TIME FOR SNOW ACROSS THE AREA. PRIMARY LOW NOW LOCATED OVER WEST
VIRGINIA WITH A SECONDARY LOW DEVELOPING NEAR WAKEFIELD VIRGINIA.
SECONDARY LOW WILL TAKE OVER DURING THE REST OF THE EVENING AND
PROGRESS TO NEAR DELAWARE BY 03Z...NEW YORK CITY BY 09Z....AND
THEN LONG ISLAND BY 12Z. JUDGING BY CURRENT OBSERVATIONS...SNOW HAS
NOW REACHED AS FAR NORTH AS THE MID-HUDSON VALLEY...THE CENTRAL
MOHAWK VALLEY...AND THE SHORES OF LAKE ONTARIO IN NEW YORK...WITH
A SLOW NORTHWARD PROGRESSION. SHOULD BE INTO THE ADIRONDACKS AND
SOUTHERN VERMONT AROUND 02Z (9 PM)...THE CHAMPLAIN VALLEY AROUND
04Z (11 PM)...AND THE NORTHEAST KINGDOM AROUND 05Z (MIDNIGHT).
HEAVIEST SNOW WITH INITIAL BAND OF WARM AIR ADVECTION
PRECIPITATION WILL LIKELY OCCUR BETWEEN 07Z AND 10Z (2 AM AND 5 AM) WHERE
RATES OF 1-2 INCHES PER HOUR ARE POSSIBLE...ESPECIALLY IN THE
SOUTHEAST- UPSLOPE FAVORED LOCATIONS. DOWNSLOPE WINDS WILL ALSO BE
INCREASING ACROSS THE SOUTHERN GREENS WITH GUSTS UP TO 40 MPH
POSSIBLE IN EASTERN ADDISON AND RUTLAND COUNTIES BETWEEN 06Z AND
10Z (1 AM AND 5 AM). THIS WILL CREATE SOME WARMING AND DRYING IN
THOSE AREAS...AND COMBINED WITH SOME WARMING ALOFT (750-800
MB) AS INDICATED BY LATEST RAP AND NAM...WILL LIKELY SEE SOME SLEET
MIX IN ACROSS RUTLAND AND WINDSOR COUNTIES AFTER 07Z...AND
ESPECIALLY AFTER 10Z.
PREVIOUS DISCUSSION FROM 325 PM EST...
CURRENTLY THE QUIET BEFORE THE STORM. HIGH/MID CLOUDS RAPIDLY
COVERING THE SKY AND THIS WILL BE THE LAST WE`LL SEE OF ANY SUN
FOR A GOOD NUMBER OF DAYS.
OVERALL THE FORECAST IS STILL ON TRACK. 12Z GUIDANCE OFFERED NO
BIG CHANGES, EXCEPT TO BOOST CONFIDENCE IN THE TRACK OF THE STORM
AND WHAT IT WILL OFFER TO OUR REGION. AS ANTICIPATED, SECONDARY
DEVELOPMENT IS OCCURRING ACROSS SOUTHEAST VIRGINIA, AND THIS LOW
WILL TAKE OVER AND BECOME THE PRIMARY ONE. IT WILL TRACK NORTHEAST
AND BY DAYBREAK THURSDAY WILL BE SITTING JUST SOUTH OF LONG
ISLAND. THE ATMOSPHERE WILL REMAIN COLD ENOUGH FOR THE P-TYPE TO
BE ALL SNOW. EVEN THE WARMEST MODEL, THE NAM, HAS TRENDED COLDER,
SO NOT ANTICIPATING ANY SIGNIFICANT SLEET MIX.
SNOW IS SPREADING ACROSS THE NY/PA BORDER. KEEP IN MIND THAT THE
LEADING EDGE OF THE RADAR RETURNS ARE VIRGA DUE TO THE DRY AIRMASS
IN PLACE. BEST ESTIMATES OF THE ONSET OF SNOWFALL IS ABOUT 8PM IN
RUTLAND, 10-11PM FOR THE ST LAWRENCE VALLEY AND SOUTHERN CHAMPLAIN
VALLEYS, AND THEN BY 1AM INTO THE NORTHEAST KINGDOM. ONCE THE SNOW
STARTS, IT WILL START TO COME DOWN RATHER HEAVY, SO TRAVEL
CONDITIONS WILL RAPIDLY DETERIORATE.
ON THE WIND ASPECT, AS THE LOW DEVELOPS A LOW/MID LEVEL EASTERLY
JET OF 50-60 KNOTS WILL ALSO DEVELOP, MAINLY AFTER 06Z TONIGHT.
ALTHOUGH WE`LL LIKELY SEE SOME DOWNSLOPING WINDS ALONG THE WESTERN
SLOPE OF THE GREENS (ESPECIALLY RUTLAND SOUTHWARD), THE MAGNITUDE
AND ATMOSPHERIC STABILITY SHOULD PRECLUDE THE STRONGEST OF WINDS
REALLY MIXING DOWN LOW. SO THOUGH WE MAY HAVE SOME LOCAL GUSTS
APPROACH 40 MPH, IT SHOULDN`T BE ENOUGH FOR WIND ADVISORY LEVELS.
THE DOWNSLOPING ALONG THE GREENS, AND TO AN EXTENT OFF THE WHITE
MOUNTAINS INTO THE NORTHEAST KINGDOM, WILL LIMIT THE AMOUNT OF
PRECIPITATION IN THOSE AREAS -- AND THIS WILL CUT THE SNOWFALL
AMOUNTS AS WELL.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
AS OF 325 PM EST WEDNESDAY...GONNA BE A BUSY DAY THURSDAY. LOTS OF
SNOW. THE STORM WILL TRACK NORTHEAST AND CUT ACROSS CAPE COD (OR
VERY NEAR IT) BY LATE IN THE AFTERNOON. THIS PUTS THE NORTH
COUNTRY INTO A SWEET SPOT FOR THE HEAVIEST QPF. THE DRY SLOT JUST
WONT GET THIS FAR NORTH, AND AS THE LOW MOVES OFF TO THE EAST,
WE`LL BE IN THE PIVOT ZONE INTO THE AFTERNOON.
EXCELLENT DYNAMICS AND SNOW GROWTH MAXED WITH UPWARD MOTION
SHOULD RESULT IN A PERIOD OF HEAVY SNOW MOST EVERYWHERE. THINKING
THE PRIMARY TIME WILL BE 6AM TO NOON, WITH RATES OF 1-2" PER HOUR.
CAN`T RULE OUT LOCALIZED MESOSCALE BAND WITH EVEN A LITTLE BIT
MORE. LIQUID QPF WILL BE QUITE IMPRESSIVE. SPENT A GOOD DEAL OF
TIME TRYING TO ACCOUNT FOR OROGRAPHIC EFFECTS AS WELL. BY THE TIME
WE GET TO THURSDAY NIGHT, MOST OF US WILL SEE ON THE ORDER OF 1 TO
1.5" OF LIQUID EQUIVALENT. SHADOWING WILL MAKE THE NUMBER A LITTLE
LOWER IN THE NORTHEAST KINGDOM AND WESTERN SLOPES OF THE SOUTHERN
GREENS, BUT THEN THAT ON THE FLIP SIDE, ORGRAPHICS WILL HELP ON
THE EASTERN SIDES OF THE GREENS AND DACKS. HAVE INCREASED THE SNOW
TOTALS A FEW INCHES ACROSS THE BOARD -- THINKING 12 TO 17 INCHES,
WITH THE JACKPOT LOCATIONS SEEING ABOUT 20". EVEN THOSE WHO SEE
THE LEAST WILL GET ABOUT 8", WHICH IS NOT SHABBY.
WINDS WILL CONTINUE TO BE GUSTY THE FIRST HALF OF THURSDAY ALONG
THE WESTERN SLOPES. ALSO HAVE TO WATCH FOR STRONG NORTHEAST WINDS
FUNNELLING DOWN THE ST LAWRENCE VALLEY. DONT THINK THEY`LL HIT
WIND ADVISORY CRITERIA, BUT STILL THEY`LL HAVE SUSTAINED WINDS 15
TO 25 MPH WITH HIGHER GUSTS -- AND THAT WILL CAUSE A CONSIDERABLE
AMOUNT OF DRIFTING/BLOWING SNOW OUT THERE. HAVE ADDED THAT WORDING
TO THE FORECAST.
SNOW WILL BEGIN TO TAPER OFF IN THE EVENING, THOUGH LIGHT SNOWS
WILL CONTINUE ALL NIGHT. AS THE LOW PUSHES EAST OF HERE, WINDS
WILL CLOCK AROUND TO NORTHWEST. MOISTURE WILL BE SLOW TO LEAVE, SO
THE NORTHWEST WINDS AND THAT MOISTURE WILL RESULT IN A GOOD AMOUNT
OF OROGRAPHICS, SO THE HIGHER TERRAIN WILL PICK UP A FEW
ADDITIONAL INCHES OF SNOW (AT LEAST) ON FRIDAY.
FINALLY TAPER POPS DOWN TO CHANCE LEVELS BY FRIDAY NIGHT, THOUGH A
WEAK SYSTEM APPROACHING FROM THE WEST MAY SPARK A LITTLE BIT OF
LIGHT SNOW/FLURRIES.
QUICK NOTE ON TEMPERATURES -- PRIMARILY KEPT TO THE COOLER SIDE OF
GUIDANCE FOR THE ENTIRE TIME.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AS OF 342 PM EST WEDNESDAY...OVERALL LITTLE CHANGE FROM PREVIOUS
COUPLE OF FCSTS...WITH BLW NORMAL TEMPS AND PRECIP EXPECTED FOR
DAYS 4 THRU 7. THE EXTENDED FCST CHALLENGE WL BE TIMING/MAGNITUDE
OF ARCTIC AIRMASS ACRS OUR CWA EARLY NEXT WK. WL CONT TO MENTION
LOW CHC POPS FOR LATE SAT INTO SUNDAY ASSOCIATED WITH MID/UPPER
LVL TROF AND SOME 850 TO 500MB RH. LATEST TRENDS HAVE BEEN FOR
LESS RH AND QPF ACRS OUR CWA...BUT ECMWF IS A BIT CLOSER TO THE
COAST WITH SFC LOW PRES AND ENOUGH MOISTURE MAY MOVE BACK INTO OUR
CWA FOR SOME LIGHT SNOW. OTHERWISE...ECMWF/GEM SHOW MID/UPPER LVL
TROF DEVELOPING ACRS EASTERN CANADA WITH A MAINLY DRY NW FLW
ALOFT. HOWEVER...A WELL DEFINED ARCTIC BOUNDARY WL PUSH ACRS OUR
CWA EARLY NEXT WEEK...ALONG WITH A RIBBON OF ENHANCED MOISTURE.
THIS MOISTURE...ALONG WITH SOME ADDITIONAL MOISTURE FROM THE GREAT
LAKES WL HELP IN PRODUCING SOME SNOW SHOWERS ACRS OUR CWA ON
MONDAY INTO TUES. IN ADDITION...MUCH COLDER TEMPS WL ADVECT BACK
INTO OUR CWA FOR NEXT WK. STILL SOME UNCERTAINTY WITH REGARDS TO
TIMING OF THIS FEATURE...AS GFS IS 6 TO 12 HRS SLOWER AND SHOWS
THE COLDEST TEMPS ACRS OUR CWA ON WEDS. TIMING OF BOUNDARY WL MAKE
A HUGE DIFFERENCE IN TEMPS FROM NEAR 30F AT BTV IF THE GFS IS
RIGHT TO LOWER TEENS IF THE ECMWF/GEM ARE CORRECT ON TUES. GIVEN THE
DEVELOPMENT OF A LARGE SCALE TROF AND DEEP CYCLONIC FLW ACRS THE
NE CONUS...WL TREND TWD THE COLDER ECMWF/GEM FOR NEXT WEEK...AND
MENTION HIGHS ONLY IN THE TEENS/L20S WITH LOWS MAINLY IN THE
SINGLE DIGITS/LOWER TEENS. IF SFC HIGH PRES BUILDS INTO THE
REGION...FASTER THAN PROGGED...THEN WINDS WL DECREASE AND
OVERNIGHT LOWS WL NEED TO BE ADJUSTED DOWN BY 5 TO 10 DEGREES. ITS
ALWAYS DIFFICULT TO DETERMINE AMOUNT OF CAA AND IMPACTS ACRS OUR
CWA IN THE DAY 5 TO 7 RANGE. TODAY IS A GREAT EXAMPLE OF TRYING TO
PREDICT THE COLD AIR...AS TEMPS STRUGGLED MAINLY IN THE TEENS.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
THROUGH 00Z FRIDAY...SNOW TO MOVE IN TO ALL TAF SITES 03-05Z,
LOWERING CONDITIONS TO LIFR TO IFR FOR ALL OF TAF PERIOD. HEAVIER BURSTS
POSSIBLE 09-14Z AT HEIGHT OF STORM. AFTER 14Z WILL BEGIN TO SEE
SLOW IMPROVEMENT...BUT STILL IFR. POTENTIAL FOR LAYER OF NEAR TO
ABOVE FREEZING AIR TO MOVE IN TO SOUTHERN VERMONT 10-15Z...AND
PRODUCE SLEET AT KRUT. TEMPERATURE PROFILE RIGHT ON THE EDGE...AND
COULD EASILY STAY ALL SNOW IF TEMPERATURES REMAIN COOL ENOUGH.
EAST TO SOUTHEAST LOW LEVEL JET TO MOVE INTO AREA OVERNIGHT...WITH
KRUT LIKELY TO EXPERIENCE STRONGEST WIND GUSTS 20-35 KTS. VALLEY
CHANNELING AT KMSS WILL PRODUCE GUSTS TO 20-25 KTS. ELSEWHERE
STRONGER WINDS LESS FAVORABLE... REMAINING SITES STILL TO SEE
15-20 KTS.
OUTLOOK 00Z FRIDAY THROUGH MONDAY...
00Z FRIDAY-00Z SATURDAY...LOW WILL MOVE INTO THE GULF OF
MAINE...SHIFTING SURFACE WINDS TO NORTHWEST. SNOW SHOWERS TO
CONTINUE ESPECIALLY IN FAVORED UPSLOPE AREAS...AND HIGHER
ELEVATION SITES KMPV/KSLK LIKELY WILL SEE CONTINUED MVFR TO IFR
CIG/VIS. MOSTLY VFR ELSEWHERE...ALTHOUGH FRESH SNOW AND GUSTY
WINDS WILL PRODUCE SOME BLOWING/DRIFTING.
00Z SATURDAY THROUGH 00Z SUNDAY...SFC HIGH PRES SLOWLY BUILDS INTO
OUR TAF SITES BY 12Z SATURDAY. SOME LEFTOVER MTN SNOW SHOWERS AT
MPV/SLK WL CREATE OCCASIONAL MVFR CONDITIONS THRU 06Z SAT...BEFORE
DISSIPATING WITH VFR CONDITIONS DEVELOPING AFT 06Z SATURDAY.
00Z SUNDAY THROUGH MONDAY...MAINLY VFR CONDITIONS WITH A CHANCE OF
MVFR SNOW SHOWERS ACROSS CENTRAL AND SOUTHERN AREAS SATURDAY NIGHT
AS LOW PRESSURE MOVES EAST ACROSS THE MID-ATLANTIC STATES.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...WINTER STORM WARNING UNTIL 7 AM EST FRIDAY FOR VTZ001>012-
016>019.
NY...WINTER STORM WARNING UNTIL 7 AM EST FRIDAY FOR NYZ026>031-034-
035-087.
&&
$$
SYNOPSIS...NASH
NEAR TERM...MUCCILLI/NASH
SHORT TERM...NASH
LONG TERM...TABER
AVIATION...HANSON
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
328 PM EST TUE DEC 25 2012
.SYNOPSIS...
HIGH PRESSURE MOVES INTO THE NORTH COUNTRY WEDNESDAY. A NOREASTER
WILL IMPACT THE REGION WEDNESDAY NIGHT THROUGH THURSDAY NIGHT WITH
THE FIRST SIGNFICANT SNOW STORM OF THE YEAR. MAINLY SNOW FOR
NORTHERN NEW YORK AND NORTHERN VERMONT WITH A POSSIBLE WINTRY MIX AT
TIMES FOR SOUTHERN AND EASTERN VERMONT. SNOW AND SNOW SHOWERS WILL
CONTINUE THROUGH FRIDAY MORNING IN THE NORTHERN MOUNTAINS.
&&
.NEAR TERM /UNTIL 7 AM WEDNESDAY MORNING/...
AS OF 323 PM EST TUESDAY...GRADUAL CLEARING WILL CONT THIS EVENING AND
OVERNIGHT WITH DEWPOINTS IN THE SINGLE NUMBERS AND FRESH SNOW
COVER..MIN T WILL BE MAINLY SINGLE NUMBERS AND MAY HAVE NOT GONE
COLD ENUF FOR ADRNDKS/NE VT...ALL BASED ON CLD COVER.
&&
.SHORT TERM /7 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
AS OF 323 PM EST TUESDAY... RIDGE OF HIGH PRESSURE ACROSS QUEBEC
AND ONTARIO NOSING INTO THE NORTH COUNTRY WILL RETREAT SLIGHTLY
DURING WEDNESDAY.
A STRONG CUT-OFF SHORTWAVE LIFTS NE ACROSS OHIO RIVER VALLEY WED
NGT AND OVER NEW ENGLAND ON THU IN A NEG TILT ORIENTATION. SFC LOW
PRESSURE MOVES FROM TENNESSEE VALLEY WED TO ALG OR JUST OFFSHORE OF
NEW JERSEY THU MRNG AND THEN NEAR OR OVER CAPE COD THU. H7 LOW IN
FAVORABLE TRACK FOR MAJOR SNOWFALL ACRS FA BUT SOMEWHAT
MARGINAL/MILDER TEMPERATURES JUST S/E ALG WITH FLOW OFF THE
ATLANTIC TRIES TO INTRODUCE SOME LOW-MID LVL WARMING FOR SRN/ERN
VT.
NWP MODELS ALL IN GOOD AGREEMENT WITH NAM12 THE MILDER MODEL BUT
EVEN WENT COOLER ON THE 12Z RUN. PRIMARILY A HEAVY SNOWFALL EVENT
WITH SOME MIX OR BRIEF CHANGE TO SLEET FOR SRN HALF OF VT AND ERN
VT AS WELL.
STRONG H8 JET (70KTS) MOVING ACRS FA WITH ITS CORE ACRS SRN AND ERN
VT WILL ALLOW FOR SOME SHADOWING AND UPSLOPE EFFECTS WHICH MAY
ACCOUNT FOR WIDE RANGES IN SNOWFALL AMTS. H925 JET OF 40-45 KTS
MAINLY ACRS SRN VT WILL RAISE SOME CONCERNS OF SOME DOWNSLOPING
WINDS BUT THE INVERSION APPEARS JUST ABOVE MOUNTAIN RIDGES.
ATTM...SCNDRY THREAT THAT CAN BE FOCUSED IN LATER FCSTS BUT WIND
GUSTS 35-40 MPH FOR A BRIEF PERIOD POSSIBLE.
AGAIN...TRIED TO INCORPORATE UPSLOPE/DOWNSLOPE CONSIDERATIONS AND A
BLEND OF NAM12/SREF/GFS/ECMWF. SOME OF THE MDLS ARE PERSISTENT WITH
MUCH HEAVIER QPF IN ST LWRNC VLY (1.5-2 INCHES) BUT HAVE ADJUSTED
DOWN. IN THE END...GENERALLY AROUND AN INCH OF QPF WITH THE
FOLLOWING EXCEPTIONS...LOWER (0.6-0.8) IN SRN WESTERN SLOPES AND NE
VT ALONG WITH SOME DOWNSLOPING IN WRN ADRNDKS WHILE HIGHER QPF
(1-1.25) ALONG ERN SLOPES OF SRN GREENS AND SE ADRNDKS.
I/M HANGING ONTO PCPN FOR NRN MTNS THU NGT AND GRADUALLY ENDING FRI
MRNG. THE MAIN ACCUM PRIOR TO 00Z FRI BUT ADDTNL UPSLOPE FOR WRN
SLOPES OF GREENS AND NE VT WHERE WILL HAVE EXPERIENCED ERLR
SHADOWING.
IN THE END...GENERAL 10-15 INCHES WITH SLIGHT LOWER FOR NE VT...ST
LWRNC VLY AND SRN GREENS WITH THE HIGHER AMTS AS MENTIONED ERLR IN
FAVORED SE UPSLOPE REGIONS.
OF NOTE...IT HAS BEEN 658 DAYS SINCE THE LAST 6+" SNOWSTORM AT BTV
(3/7/11) AND THIS WILL LIKELY BREAK THAT STREAK.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
AS OF 350 PM EST TUESDAY...OVERALL ACTIVE WX PATTERN CONTS WITH
ADDITIONAL CHCS FOR SNOW OVER THE WKND INTO EARLY NEXT WK.
HOWEVER...LATEST TRENDS IN GUIDANCE SHOW LIMITED PHASING FOR
WEEKEND SYSTEM...WHICH WL KEEP BEST DEEP LAYER MOISTURE/LIFT TO
OUR SOUTH AND EAST...ASSOCIATED WITH SFC LOW TRACKING SOUTHEAST OF
THE BENCHMARK. STILL PLENTY OF UNCERTAINTY AS S/W ENERGY EJECTS
FROM WESTERN TROF...AS MODELS TEND TO PERFORM POORLY IN THE
WESTERN MTNS IN THE DAY 4 THRU 6 PERIOD. STILL ANTICIPATING SOME
LIGHT SNOW ASSOCIATED WITH MID/UPPER LVL TROF AND LEFTOVER 850 TO
500MB RH IN TROF AXIS FOR LATE SAT INTO SUN. OTHERWISE...DEEP
CYCLONIC FLW DEVELOPS AS LOW PRES INTENSIFIES ACRS THE CANADIAN
MARITIMES. THIS WL PUSH MUCH COLDER TEMPS ACRS OUR CWA FOR EARLY
NEXT WEEK...ALONG WITH A CHC FOR MAINLY MTN SNOW SHOWERS. BASED ON
EXPECTED FRESH SNOW COVER AND COOL NORTHERLY FLW...WL CUT MACHINE
NUMBERS BY SEVERAL DEGREES THRU THE PERIOD. THINKING MAINLY 20S
FOR THE WEEKEND...BUT HIGHS FALLING BACK INTO THE TEENS AND LOWER
20S NEXT WK...WITH LOWS NEAR NORMAL.
&&
.AVIATION /21Z TUESDAY THROUGH SUNDAY/...
THROUGH 18Z WEDNESDAY...AVIATION CHALLENGE THRU 18Z WEDS WL
POTENTIAL FOR LOW CLOUDS AND IFR CONDITIONS AT BTV/MPV/SLK/RUT.
SFC ANALYSIS SHOWS LIGHT SNOW FROM THIS MORNING...QUICKLY
DISSIPATING WITH SFC HIGH PRES BUILDING INTO OUR NORTHERN TAF
SITES. THIS HAS RESULTED IN CLRING SKIES AND DRIER AIR TO ADVECT
INTO THE REGION WITH SFC DWPTS IN THE SINGLE DIGITS. QUESTION
TONIGHT WL BE AMOUNT OF LLVL MOISTURE IN MODIFIED ARCTIC AIRMASS
AND POTENTIAL FOR CLOUDS. NAM12 AND RAP SOUNDINGS SHOW LLVL RH
DEVELOPING ACRS BTV/SLK/MPV THIS EVENING...WITH POTENTIAL FOR IFR
CIGS. GIVEN SOME CLOUDS UPSTREAM AND SOUNDINGS SHOWING GOOD RH
BTWN SFC AND 800MB...EXPECT SOME LOW CLOUDS WITH A FEW FLURRIES
POSSIBLE AT MPV/SLK/BTV...WL USE TEMPO GROUP TO COVER MVFR TO
POTENTIALLY IFR CONDITIONS OVERNIGHT...ESPECIALLY AT SLK.
OTHERWISE...MSS/RUT/PBG SHOULD STAY VFR THRU 18Z WEDS.
OUTLOOK 18Z WEDNESDAY THROUGH SATURDAY...
SIGNIFICANT STORM WL HAVE MAJOR IMPACTS ON THE AVIATION COMMUNITY
FROM 06Z THURS THRU 12Z FRIDAY WITH LONG DURATIONS OF IFR/LIFR IN
PERIODS OF MODERATE TO HEAVY SNOW AND LOW CIGS. SOME SLEET WL BE
POSSIBLE AT RUT/MPV ON THURSDAY...WITH EASTERLY WIND GUSTS TO 45
MPH POSSIBLE AT RUT. THESE GUSTY WINDS WL CREATE AREAS OF BLOWING
SNOW AND TURBULENCE AT ALL SITES...ESPECIALLY ON THURSDAY ASSOCIATED
WITH A LLVL JET OF 40 TO 60 KNTS. FLYING CONDITIONS WL SLOWLY
IMPROVE ON FRIDAY AFTN...WITH VFR CONDITIONS LIKELY BY FRIDAY
NIGHT AND SATURDAY.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...WINTER STORM WARNING FROM 7 PM WEDNESDAY TO 7 AM EST FRIDAY
FOR VTZ001>012-016>019.
NY...WINTER STORM WARNING FROM 7 PM WEDNESDAY TO 7 AM EST FRIDAY
FOR NYZ026>031-034-035-087.
&&
$$
SYNOPSIS...SLW
NEAR TERM...SLW
SHORT TERM...SLW
LONG TERM...TABER
AVIATION...TABER
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
323 PM EST TUE DEC 25 2012
.SYNOPSIS...
A WEAK UPPER LEVEL DISTURBANCE WILL BRING SOME LIGHT SNOW TO
PORTIONS OF THE NORTH COUNTRY ON THIS CHRISTMAS MORNING. FAIR AND
SEASONABLY COLD CONDITIONS ARE EXPECTED TONIGHT AND WEDNESDAY. A
NOR EASTER WILL AFFECT THE REGION WITH HEAVY SNOW WEDNESDAY NIGHT
AND THURSDAY. THIS WILL RESULT IN SIGNIFICANT TRAVEL IMPACTS WITH
SNOW COVERED ROADS AND LOW VISIBILITY...AND THE POTENTIAL FOR
HEAVY SNOW ACCUMULATION ACROSS THE NORTH COUNTRY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 942 AM EST TUESDAY...VERY SIMILAR TO LAST UPDATE.
FORECAST PRETTY MUCH ON TRACK. WITH LATEST UPDATE...ONLY MINOR
ADJUSTMENTS TO HOURLY PARAMETERS FOR THIS MORNING TO REFLECT
LATEST CONDITIONS AND TRENDS. SOME LIGHT SNOW FALLING ACROSS
PORTIONS OF THE FORECAST AREA ON THIS CHRISTMAS MORNING. RADAR
LOOKS A BIT MORE OMINOUS THAN WHAT IS BEING REPORTED ON OBS...AS
LOW LEVELS QUITE DRY IN ADVANCE OF THE PRECIPITATION. STILL
LOOKING AT ONLY LIGHT ACCUMULATIONS WITH A DUSTING TO 2 INCHES
EXPECTED...MAINLY SOUTH.
PREVIOUS DISCUSSION...
AN UPPER LEVEL DISTURBANCE MOVING EAST FROM THE GREAT LAKES WILL
BRING SOME LIGHT SNOW TO PORTIONS OF THE FORECAST AREA THIS
MORNING. WEAK SURFACE LOW ASSOCIATED WITH THE DISTURBANCE WILL
PASS SOUTH OF NEW ENGLAND THROUGH MIDDAY. BEST CHANCE FOR SEEING
AN INCH OR TWO OF SNOW ACCUMULATION WILL BE OVER SOUTHERN PORTIONS
OF THE AREA...WHILE JUST A DUSTING IS EXPECTED ACROSS THE FAR
NORTHERN TIER OF ZONES. AS BOTH THE UPPER LEVEL SHORTWAVE AND
SURFACE DISTURBANCE MOVE EAST OF THE REGION THIS AFTERNOON...THE
CHANCES FOR LIGHT SNOW WILL DIMINISH...ALTHOUGH SKIES WILL REMAIN
GENERALLY CLOUDY. MAX TEMPS EXPECTED TO BE IN MOSTLY IN THE 20S.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
AS OF 502 AM EST TUESDAY...SHORT-TERM PERIOD BEGINS QUIET...BUT ENDS
WITH THE A SIGNIFICANT NOR`EASTER WHICH IS LIKELY TO BRING A HEAVY
SNOWFALL TO THE REGION BEGINNING WEDNESDAY NIGHT.
A RIDGE OF HIGH PRESSURE BUILDS INTO THE REGION FROM THE NORTHWEST
TONIGHT AND THRU THE DAY WEDNESDAY BRINGING DRY WEATHER AND
SEASONABLY COLD TEMPERATURES TO THE NORTH COUNTRY. AMOUNT OF
CLEARING WE SEE TONIGHT IS IN QUESTION...AS SOME MODEL SOUNDINGS
INDICATING AN ABUNDANCE OF LOW LEVEL MOISTURE OVER THE REGION.
HAVE GONE WITH A FORECAST OF PARTLY CLOUDY...AND RAISED TEMPS A
FEW DEGREES FROM MOS GUIDANCE NUMBERS. EXPECT LOWS IN THE SINGLE
NUMBERS AND TEENS. LOOK FOR A CONTINUATION OF PARTLY CLOUDY SKIES
DURING WEDNESDAY...ALTHOUGH AN INCREASE IN CLOUDS CAN BE EXPECTED
LATER IN THE DAY.
NWP MODELS ALL IN GOOD AGREEMENT WITH LOW PRESSURE OVER THE
TENNESSEE VALLEY WEDNESDAY REDEVELOPING ALONG MID-ATLANTIC COAST
AT 00Z THURSDAY...LIFTING NNEWD ALONG THE NEW JERSEY COAST BY 12Z
THURSDAY. STRONG NEGATIVE TILT 500MB WAVE DRAWS SIGNIFICANT MOISTURE
NORTHWARD INTO THE FORECAST AREA WITH STRONG SYNOPTIC ASCENT
BEGINNING AFTER MIDNIGHT. ONCE SNOW DEVELOPS...IT APPEARS FROM MODEL
SOUNDINGS THAT INTENSITY WILL INCREASE QUICKLY WITH SNOW BECOMING
HEAVY AT TIMES WITH STRONG UVV AND DENDRITE SNOW GROWTH. HAVE
CONTINUED WITH PREVIOUS THINKING OF HEAVY SNOW DEVELOPING LATE
WEDNESDAY NIGHT...WITH SEVERAL INCHES OF SNOW ON THE GROUND BY
DAYBREAK THURSDAY. PERIOD OF HEAVIEST PRECIPITATION CONTINUES
THROUGH ABOUT 18Z THURSDAY...THEN BEGINS TO DIMINISH AS SURFACE LOW
REACHES GULF OF MAINE BY THURSDAY EVENING. BY NIGHTFALL...EXPECT
SNOW ACCUMULATIONS OF 8 TO 13 INCHES ACROSS MUCH OF THE REGION.
HAVE GONE WITH 12:1-14:1 SNOW RATIO...WHICH IS COMMON FOR THESE
TYPES OF SYSTEMS WITH E-SE 850MB FETCH ACROSS THE REGION.
ALTHOUGH MOST MODELS ARE IN GOOD AGREEMENT REGARDING THE STORM
TRACK...IT SHOULD BE NOTED THAT THE NAM HAS CONTINUED WITH A TRACK A
BIT FURTHER WEST...WHICH IF PROVEN CORRECT COULD POSE SOME PROBLEMS.
THE RESULT WOULD BE POTENTIALLY STRONG GUSTY WINDS...ESPECIALLY
ALONG THE WEST WESTERN SLOPES OF THE GREEN MOUNTAINS. IT WOULD
ALSO ALLOW FOR MORE MIXED PRECIPITATION ACROSS MUCH OF VERMONT.
THE MIXTURE COMBINED WITH SHADOWING WOULD LIKELY REDUCE SNOW
AMOUNTS SIGNIFICANTLY FROM THE GOING FORECAST. SO CONFIDENCE NOT
THE GREATEST IN THE FORECAST DETAILS...ESPECIALLY FOR SOUTHERN AND
EASTERN VERMONT. IN ANY EVENT THOUGH...IT WILL BE A SIGNIFICANT
STORM WITH MAJOR IMPACTS TO THE ENTIRE FORECAST AREA.
OF NOTE...IT HAS BEEN 658 DAYS SINCE THE LAST 6+" SNOWSTORM AT BTV
(3/7/11) AND THIS WILL LIKELY BREAK THAT STREAK.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
AS OF 350 PM EST TUESDAY...OVERALL ACTIVE WX PATTERN CONTS WITH
ADDITIONAL CHCS FOR SNOW OVER THE WKND INTO EARLY NEXT WK.
HOWEVER...LATEST TRENDS IN GUIDANCE SHOW LIMITED PHASING FOR
WEEKEND SYSTEM...WHICH WL KEEP BEST DEEP LAYER MOISTURE/LIFT TO
OUR SOUTH AND EAST...ASSOCIATED WITH SFC LOW TRACKING SOUTHEAST OF
THE BENCHMARK. STILL PLENTY OF UNCERTAINTY AS S/W ENERGY EJECTS
FROM WESTERN TROF...AS MODELS TEND TO PERFORM POORLY IN THE
WESTERN MTNS IN THE DAY 4 THRU 6 PERIOD. STILL ANTICIPATING SOME
LIGHT SNOW ASSOCIATED WITH MID/UPPER LVL TROF AND LEFTOVER 850 TO
500MB RH IN TROF AXIS FOR LATE SAT INTO SUN. OTHERWISE...DEEP
CYCLONIC FLW DEVELOPS AS LOW PRES INTENSIFIES ACRS THE CANADIAN
MARITIMES. THIS WL PUSH MUCH COLDER TEMPS ACRS OUR CWA FOR EARLY
NEXT WEEK...ALONG WITH A CHC FOR MAINLY MTN SNOW SHOWERS. BASED ON
EXPECTED FRESH SNOW COVER AND COOL NORTHERLY FLW...WL CUT MACHINE
NUMBERS BY SEVERAL DEGREES THRU THE PERIOD. THINKING MAINLY 20S
FOR THE WEEKEND...BUT HIGHS FALLING BACK INTO THE TEENS AND LOWER
20S NEXT WK...WITH LOWS NEAR NORMAL.
&&
.AVIATION /20Z TUESDAY THROUGH SUNDAY/...
THROUGH 18Z WEDNESDAY...AVIATION CHALLENGE THRU 18Z WEDS WL
POTENTIAL FOR LOW CLOUDS AND IFR CONDITIONS AT BTV/MPV/SLK/RUT.
SFC ANALYSIS SHOWS LIGHT SNOW FROM THIS MORNING...QUICKLY
DISSIPATING WITH SFC HIGH PRES BUILDING INTO OUR NORTHERN TAF
SITES. THIS HAS RESULTED IN CLRING SKIES AND DRIER AIR TO ADVECT
INTO THE REGION WITH SFC DWPTS IN THE SINGLE DIGITS. QUESTION
TONIGHT WL BE AMOUNT OF LLVL MOISTURE IN MODIFIED ARCTIC AIRMASS
AND POTENTIAL FOR CLOUDS. NAM12 AND RAP SOUNDINGS SHOW LLVL RH
DEVELOPING ACRS BTV/SLK/MPV THIS EVENING...WITH POTENTIAL FOR IFR
CIGS. GIVEN SOME CLOUDS UPSTREAM AND SOUNDINGS SHOWING GOOD RH
BTWN SFC AND 800MB...EXPECT SOME LOW CLOUDS WITH A FEW FLURRIES
POSSIBLE AT MPV/SLK/BTV...WL USE TEMPO GROUP TO COVER MVFR TO
POTENTIALLY IFR CONDITIONS OVERNIGHT...ESPECIALLY AT SLK.
OTHERWISE...MSS/RUT/PBG SHOULD STAY VFR THRU 18Z WEDS.
OUTLOOK 18Z WEDNESDAY THROUGH SATURDAY...
SIGNIFICANT STORM WL HAVE MAJOR IMPACTS ON THE AVIATION COMMUNITY
FROM 06Z THURS THRU 12Z FRIDAY WITH LONG DURATIONS OF IFR/LIFR IN
PERIODS OF MODERATE TO HEAVY SNOW AND LOW CIGS. SOME SLEET WL BE
POSSIBLE AT RUT/MPV ON THURSDAY...WITH EASTERLY WIND GUSTS TO 45
MPH POSSIBLE AT RUT. THESE GUSTY WINDS WL CREATE AREAS OF BLOWING
SNOW AND TURBULENCE AT ALL SITES...ESPECIALLY ON THURSDAY ASSOCIATED
WITH A LLVL JET OF 40 TO 60 KNTS. FLYING CONDITIONS WL SLOWLY
IMPROVE ON FRIDAY AFTN...WITH VFR CONDITIONS LIKELY BY FRIDAY
NIGHT AND SATURDAY.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...WINTER STORM WARNING FROM 7 PM WEDNESDAY TO 7 AM EST FRIDAY
FOR VTZ001>012-016>019.
NY...WINTER STORM WARNING FROM 7 PM WEDNESDAY TO 7 AM EST FRIDAY
FOR NYZ026>031-034-035-087.
&&
$$
SYNOPSIS...RJS
NEAR TERM...RJS/SLW
SHORT TERM...RJS
LONG TERM...TABER
AVIATION...TABER
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
1254 PM EST TUE DEC 25 2012
.SYNOPSIS...
A WEAK UPPER LEVEL DISTURBANCE WILL BRING SOME LIGHT SNOW TO
PORTIONS OF THE NORTH COUNTRY ON THIS CHRISTMAS MORNING. FAIR AND
SEASONABLY COLD CONDITIONS ARE EXPECTED TONIGHT AND WEDNESDAY. A
NOR EASTER WILL AFFECT THE REGION WITH HEAVY SNOW WEDNESDAY NIGHT
AND THURSDAY. THIS WILL RESULT IN SIGNIFICANT TRAVEL IMPACTS WITH
SNOW COVERED ROADS AND LOW VISIBILITY...AND THE POTENTIAL FOR
HEAVY SNOW ACCUMULATION ACROSS THE NORTH COUNTRY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 942 AM EST TUESDAY...VERY SIMILAR TO LAST UPDATE.
FORECAST PRETTY MUCH ON TRACK. WITH LATEST UPDATE...ONLY MINOR
ADJUSTMENTS TO HOURLY PARAMETERS FOR THIS MORNING TO REFLECT
LATEST CONDITIONS AND TRENDS. SOME LIGHT SNOW FALLING ACROSS
PORTIONS OF THE FORECAST AREA ON THIS CHRISTMAS MORNING. RADAR
LOOKS A BIT MORE OMINOUS THAN WHAT IS BEING REPORTED ON OBS...AS
LOW LEVELS QUITE DRY IN ADVANCE OF THE PRECIPITATION. STILL
LOOKING AT ONLY LIGHT ACCUMULATIONS WITH A DUSTING TO 2 INCHES
EXPECTED...MAINLY SOUTH.
PREVIOUS DISCUSSION...
AN UPPER LEVEL DISTURBANCE MOVING EAST FROM THE GREAT LAKES WILL
BRING SOME LIGHT SNOW TO PORTIONS OF THE FORECAST AREA THIS
MORNING. WEAK SURFACE LOW ASSOCIATED WITH THE DISTURBANCE WILL
PASS SOUTH OF NEW ENGLAND THROUGH MIDDAY. BEST CHANCE FOR SEEING
AN INCH OR TWO OF SNOW ACCUMULATION WILL BE OVER SOUTHERN PORTIONS
OF THE AREA...WHILE JUST A DUSTING IS EXPECTED ACROSS THE FAR
NORTHERN TIER OF ZONES. AS BOTH THE UPPER LEVEL SHORTWAVE AND
SURFACE DISTURBANCE MOVE EAST OF THE REGION THIS AFTERNOON...THE
CHANCES FOR LIGHT SNOW WILL DIMINISH...ALTHOUGH SKIES WILL REMAIN
GENERALLY CLOUDY. MAX TEMPS EXPECTED TO BE IN MOSTLY IN THE 20S.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/...
AS OF 502 AM EST TUESDAY...SHORT-TERM PERIOD BEGINS QUIET...BUT ENDS
WITH THE A SIGNIFICANT NOR`EASTER WHICH IS LIKELY TO BRING A HEAVY
SNOWFALL TO THE REGION BEGINNING WEDNESDAY NIGHT.
A RIDGE OF HIGH PRESSURE BUILDS INTO THE REGION FROM THE NORTHWEST
TONIGHT AND THRU THE DAY WEDNESDAY BRINGING DRY WEATHER AND
SEASONABLY COLD TEMPERATURES TO THE NORTH COUNTRY. AMOUNT OF
CLEARING WE SEE TONIGHT IS IN QUESTION...AS SOME MODEL SOUNDINGS
INDICATING AN ABUNDANCE OF LOW LEVEL MOISTURE OVER THE REGION.
HAVE GONE WITH A FORECAST OF PARTLY CLOUDY...AND RAISED TEMPS A
FEW DEGREES FROM MOS GUIDANCE NUMBERS. EXPECT LOWS IN THE SINGLE
NUMBERS AND TEENS. LOOK FOR A CONTINUATION OF PARTLY CLOUDY SKIES
DURING WEDNESDAY...ALTHOUGH AN INCREASE IN CLOUDS CAN BE EXPECTED
LATER IN THE DAY.
NWP MODELS ALL IN GOOD AGREEMENT WITH LOW PRESSURE OVER THE
TENNESSEE VALLEY WEDNESDAY REDEVELOPING ALONG MID-ATLANTIC COAST
AT 00Z THURSDAY...LIFTING NNEWD ALONG THE NEW JERSEY COAST BY 12Z
THURSDAY. STRONG NEGATIVE TILT 500MB WAVE DRAWS SIGNIFICANT MOISTURE
NORTHWARD INTO THE FORECAST AREA WITH STRONG SYNOPTIC ASCENT
BEGINNING AFTER MIDNIGHT. ONCE SNOW DEVELOPS...IT APPEARS FROM MODEL
SOUNDINGS THAT INTENSITY WILL INCREASE QUICKLY WITH SNOW BECOMING
HEAVY AT TIMES WITH STRONG UVV AND DENDRITE SNOW GROWTH. HAVE
CONTINUED WITH PREVIOUS THINKING OF HEAVY SNOW DEVELOPING LATE
WEDNESDAY NIGHT...WITH SEVERAL INCHES OF SNOW ON THE GROUND BY
DAYBREAK THURSDAY. PERIOD OF HEAVIEST PRECIPITATION CONTINUES
THROUGH ABOUT 18Z THURSDAY...THEN BEGINS TO DIMINISH AS SURFACE LOW
REACHES GULF OF MAINE BY THURSDAY EVENING. BY NIGHTFALL...EXPECT
SNOW ACCUMULATIONS OF 8 TO 13 INCHES ACROSS MUCH OF THE REGION.
HAVE GONE WITH 12:1-14:1 SNOW RATIO...WHICH IS COMMON FOR THESE
TYPES OF SYSTEMS WITH E-SE 850MB FETCH ACROSS THE REGION.
ALTHOUGH MOST MODELS ARE IN GOOD AGREEMENT REGARDING THE STORM
TRACK...IT SHOULD BE NOTED THAT THE NAM HAS CONTINUED WITH A TRACK A
BIT FURTHER WEST...WHICH IF PROVEN CORRECT COULD POSE SOME PROBLEMS.
THE RESULT WOULD BE POTENTIALLY STRONG GUSTY WINDS...ESPECIALLY
ALONG THE WEST WESTERN SLOPES OF THE GREEN MOUNTAINS. IT WOULD
ALSO ALLOW FOR MORE MIXED PRECIPITATION ACROSS MUCH OF VERMONT.
THE MIXTURE COMBINED WITH SHADOWING WOULD LIKELY REDUCE SNOW
AMOUNTS SIGNIFICANTLY FROM THE GOING FORECAST. SO CONFIDENCE NOT
THE GREATEST IN THE FORECAST DETAILS...ESPECIALLY FOR SOUTHERN AND
EASTERN VERMONT. IN ANY EVENT THOUGH...IT WILL BE A SIGNIFICANT
STORM WITH MAJOR IMPACTS TO THE ENTIRE FORECAST AREA.
OF NOTE...IT HAS BEEN 658 DAYS SINCE THE LAST 6+" SNOWSTORM AT BTV
(3/7/11) AND THIS WILL LIKELY BREAK THAT STREAK.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
AS OF 350 AM EST TUESDAY...SURFACE LOW PRESSURE WILL BE LOCATED
JUST NORTHEAST OF CAPE COD BY 00Z FRIDAY...SHIFTING NORTHEAST
INTO THE GULF OF MAINE THROUGH THE NIGHT. THE COMBINATION OF
ABUNDANT LOW LEVEL MOISTURE AND SURFACE/MID-LEVEL WINDS SHIFTING
TO THE NORTH/NORTHWEST WILL CREATE A FAVORABLE ENVIRONMENT FOR
CONTINUED MODERATE SNOW ACROSS THE REGION...ESPECIALLY ACROSS THE
FAVORED UPSLOPE LOCALES ALONG THE WESTERN SLOPES OF THE NORTHERN
GREEN MOUNTAINS AND NORTHERN ADIRONDACKS. ADDITIONAL SNOWFALL
AMOUNTS OF 2-3" ARE LIKELY THURSDAY NIGHT...WITH STORM TOTALS
ACROSS THE REGION LOOKING TO BE IN THE 10-16" RANGE BY FRIDAY
MORNING WITH LOCALIZED HIGHER AMOUNTS ACROSS THE HIGHER
ELEVATIONS.
12-18Z FRIDAY...SURFACE LOW RACES NORTHEAST TO THE GULF OF SAINT
LAWRENCE AND OVER NEWFOUNDLAND DRAGGING THE BULK OF LOW/MID LEVEL
MOISTURE ALONG WITH IT. THUS...SOME LINGERING SNOW SHOWERS ARE
POSSIBLE ACROSS NORTHEAST PORTIONS OF THE AREA...BUT SHOULD BE
FAIRLY LIGHT AND TAPERING OFF BY THE AFTERNOON AS SURFACE HIGH
PRESSURE BEGINS TO BUILD INTO THE NORTHEAST. THIS SURFACE HIGH
REMAINS OVER THE REGION THROUGH SATURDAY WITH GENERALLY DRY
CONDITIONS EXPECTED. UPPER FLOW REMAINS FAIRLY ZONAL THROUGH THIS
PERIOD WITH SEVERAL WEAK EMBEDDED VORTS MOVING THROUGH THE FLOW SO
WHILE HIGH PRESSURE WILL BE OVER THE REGION AT THE SURFACE...EXPECT
SKIES TO REMAIN PRETTY CLOUDY THROUGH THIS TIME-FRAME.
NEXT SYSTEM IN LINE TO AFFECT THE NORTHEAST COMES SATURDAY NIGHT AS
A POTENT UPPER TROUGH MOVING OUT OF THE MIDWEST DEVELOPS SURFACE LOW
PRESSURE OFF THE CAROLINA COAST. LATEST LONG RANGE MODELS OF THE
ECMWF AND GFS ARE IN GOOD AGREEMENT SHOWING THIS LOW STAYING SOUTH
OF THE FORECAST AREA THOUGH...AND MAINLY AFFECTING THE MID-
ATLANTIC STATES WITH MAYBE SOME LIGHT SNOW ACCUMULATIONS ACROSS
FAR SOUTHERN VERMONT.
BEYOND THE WEEKEND...LARGE SCALE TROUGH REMAINS OVER THE REGION WITH
BELOW NORMAL TEMPERATURES AND A CHANCE FOR SNOW SHOWERS EXPECTED.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
THROUGH 18Z WEDNESDAY...AVIATION CHALLENGE THRU 18Z WEDS WL
POTENTIAL FOR LOW CLOUDS AND IFR CONDITIONS AT BTV/MPV/SLK/RUT.
SFC ANALYSIS SHOWS LIGHT SNOW FROM THIS MORNING...QUICKLY
DISSIPATING WITH SFC HIGH PRES BUILDING INTO OUR NORTHERN TAF
SITES. THIS HAS RESULTED IN CLRING SKIES AND DRIER AIR TO ADVECT
INTO THE REGION WITH SFC DWPTS IN THE SINGLE DIGITS. QUESTION
TONIGHT WL BE AMOUNT OF LLVL MOISTURE IN MODIFIED ARCTIC AIRMASS
AND POTENTIAL FOR CLOUDS. NAM12 AND RAP SOUNDINGS SHOW LLVL RH
DEVELOPING ACRS BTV/SLK/MPV THIS EVENING...WITH POTENTIAL FOR IFR
CIGS. GIVEN SOME CLOUDS UPSTREAM AND SOUNDINGS SHOWING GOOD RH
BTWN SFC AND 800MB...EXPECT SOME LOW CLOUDS WITH A FEW FLURRIES
POSSIBLE AT MPV/SLK/BTV...WL USE TEMPO GROUP TO COVER MVFR TO
POTENTIALLY IFR CONDITIONS OVERNIGHT...ESPECIALLY AT SLK.
OTHERWISE...MSS/RUT/PBG SHOULD STAY VFR THRU 18Z WEDS.
OUTLOOK 18Z WEDNESDAY THROUGH SATURDAY...
SIGNIFICANT STORM WL HAVE MAJOR IMPACTS ON THE AVIATION COMMUNITY
FROM 06Z THURS THRU 12Z FRIDAY WITH LONG DURATIONS OF IFR/LIFR IN
PERIODS OF MODERATE TO HEAVY SNOW AND LOW CIGS. SOME SLEET WL BE
POSSIBLE AT RUT/MPV ON THURSDAY...WITH EASTERLY WIND GUSTS TO 45
MPH POSSIBLE AT RUT. THESE GUSTY WINDS WL CREATE AREAS OF BLOWING
SNOW AND TURBULENCE AT ALL SITES...ESPECIALLY ON THURSDAY ASSOCIATED
WITH A LLVL JET OF 40 TO 60 KNTS. FLYING CONDITIONS WL SLOWLY
IMPROVE ON FRIDAY AFTN...WITH VFR CONDITIONS LIKELY BY FRIDAY
NIGHT AND SATURDAY.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...WINTER STORM WATCH FROM WEDNESDAY EVENING THROUGH FRIDAY
MORNING FOR VTZ001>012-016>019.
NY...WINTER STORM WATCH FROM WEDNESDAY EVENING THROUGH FRIDAY
MORNING FOR NYZ026>031-034-035-087.
&&
$$
SYNOPSIS...RJS
NEAR TERM...RJS/SLW
SHORT TERM...RJS
LONG TERM...LAHIFF
AVIATION...TABER
AREA FORECAST DISCUSSION
NWS RALEIGH NC
300 PM EST TUE DEC 25 2012
.SYNOPSIS...
WEAK HIGH PRESSURE WILL EXTEND ACROSS THE REGION TODAY THEN SHIFT
OFFSHORE BY SUNSET. A WARM FRONT AND A DEEPENING LOW PRESSURE SYSTEM
WILL APPROACH FROM THE SOUTHWEST TONIGHT. THE STRONG STORM SYSTEM
AND ACCOMPANYING COLD FRONT WILL SWEEP ACROSS THE AREA WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 945 AM TUESDAY...
WHILE FOG AND LOW CLOUDS HAVE SCOURED ACROSS MUCH OF THE CENTRAL AND
EASTERN CWA...DENSE FOG IS STILL REPORTED IN THE TRIAD...AND TRAFFIC
CAMERAS IN THE AREA SHOW MURKY CONDITIONS ALONG THE I-40 CORRIDOR.
VISIBILITIES HAVE IMPROVED IN RANDOLPH AND DAVIDSON COUNTIES...AND
THERE IS STILL A COUPLE MORE HOURS FOR THE FOG AND STRATUS TO MIX
OUT BEFORE HIGH CLOUDS BEGIN TO POUR BACK IN AHEAD OF THE STORMS
SYSTEM DEVELOPING OVER THE GULF COAST. RAP FORECAST
SOUNDINGS...WHICH SHOW MORE LOW LEVEL MOISTURE THAN WAS OBSERVED ON
THE MORNING RAOBS....SHOW THE LOW CLOUDS SCOURING IN THE TRIAD BY
AROUND NOON. WILL INCREASE CLOUD COVER IN THE NORTHWEST PIEDMONT
AND TRIM OFF A COUPLE DEGREES ON HIGHS SINCE CIRRUS WILL BE STEADILY
INCREASING EVEN AFTER THE LOW CLOUDS BURN OFF. OTHERWISE..THE
FORECAST APPEARS TO BE IN GOOD SHAPE THROUGH 00Z. HIGHS 52-61
NORTHWEST TO SOUTHEAST. -SMITH
TONIGHT...A WARM FRONT WILL DEVELOP ACROSS SC THIS EVENING IN
RESPONSE TO A POWERFUL LOW PRESSURE SYSTEM LIFTING ACROSS THE LOWER
MS VALLEY. SLY WINDS A FEW THOUSAND FEET ABOVE THE SURFACE WILL
ADVECT WARM MOIST AIR UP AND OVER THE COOL STABLE SURFACE LAYER
RESIDING OVER CENTRAL NC. THIS WILL LEAD TO THE DEVELOPMENT OF LOW
CLOUDS...EXPANDING SW-NE IN THE EVENING. ISENTROPIC LIFT WILL
INCREASE LATE THIS EVENING INTO THE OVERNIGHT CAUSING AN EXPANSIVE
AREA OF MODERATE RAINFALL TO DEVELOP. THE GREATEST RAINFALL AMOUNTS
SHOULD FALL OVER THE WESTERN PIEDMONT WHERE BEST LIFT PROJECTED TO
BE FOCUS. TEMPS WILL INITIALLY FALL WITH ONSET OF THE RAIN DUE TO
EVAPORATIVE COOLING IN THE SUB-CLOUD LAYER AFTERWHICH TEMPS WILL
STABILIZE AND MAY ACTUALLY RISE IN THE PRE-DAWN HOURS ACROSS THE
SOUTH AS THE WARM FRONT APPROACHES FROM THE SOUTH. MIN TEMPS NEAR 40
FAR NORTH TO THE MID 40S SOUTH.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY/...
AS OF 300 PM TUESDAY...
THE STORM WILL BE OFF THE JERSEY COAST THURSDAY MORNING WITH A
STRONG PRESSURE GRADIENT PRODUCING BRISK NORTHWEST BREEZE AT AROUND
15 MPH WITH GUSTS TO PERHAPS 30 MPH. ENSUING DRY AND COLD AIR
ADVECTION WILL LIMIT HIGHS TO THE MID 40S IN THE NORTHWEST TO
PERHAPS SOME LOWER 50S ACROSS THE SOUTH. WEAKENING GRADIENT WITH
SURFACE HIGH PRESSURE BUILDING IN THURSDAY NIGHT...CLEAR SKIES WILL
PRODUCE OPTIMAL RADIATIONAL COOLING WITH MINS MOSTLY IN THE UPPER
20S. THE SURFACE HIGH WILL BE OVERHEAD BRIEFLY ON FRIDAY...ALLOWING
ONLY A MODEST INCREASE IN HIGH TEMPS...MOSTLY LOWER 50S. HIGH
CLOUDINESS WILL BE ON THE INCREASE AS A 130+ KT SOUTHERLY JET
FLATTENS THE UPPER RIDGING AND TAKES AIM INTO THE MID ATLANTIC.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 300 PM TUESDAY...
MOISTURE ADVECTION WILL BE UNDERWAY IN BACKING WINDS AHEAD OF OUR
NEXT APPROACHING SYSTEM ON FRIDAY NIGHT. ISENTROPIC LIFT WILL BE
MAXIMIZED LATE FRIDAY NIGHT...AND WILL SMEAR SLIGHT CHANCE POPS
ACROSS MAINLY THE WEST AND SOUTH BY MORNING. MINS WILL BE TEMPERED
BY INCREASING CLOUDINESS AND WEAK WARM AIR ADVECTION...LOW TO MID
30S.
THE SYSTEM TRANSLATES ACROSS THE AREA QUICKLY ON SATURDAY WITH
STRENTHENING DELAYED UNTIL IT IS WELL CLEAR OF THE MID ATLANTIC
COAST. EXPECT A RAPID MOISTURE ADVECTION CUTOFF AS THE LOW LEVEL
FLOW VEERS WEST ACROSS THE GULF STATES BY EARLY AFTERNOON. WILL
CONTINUE LIKELY POPS ACROSS THE WEST IN THE MORNING AND IN THE EAST
IN THE AFTERNOON...ALTHOUGH RAINFALL AMOUNTS WILL BE ON THE LIGHT
SIDE DUE TO THE SPEED AND LIMITED MOISTURE. THE QUICK SHUTOFF OF
WARM AIR ADVECTION AND EVAPORATIVE COOLING WILL LIMIT HIGHS TO
MOSTLY MID AND UPPER 40S.
UNSEASONABLY COOL HIGH PRESSURE BUILDS IN BEHIND THIS SYSTEM...WITH
TRANQUIL WEATHER FOR THE REMAINDER OF THE FORECAST. HIGHS WILL TOP
OUT IN THE LOW TO MID 40S ON SUNDAY AFTER A COOL MORNING START IN
THE UPPER 20S. HIGH OVERHEAD SUNDAY NIGHT WILL ALLOW STRONG
RADIATIONAL COOLING...MINS IN THE MID...PERHAPS LOWER...20S. NEXT
UPPER TROF DIGGING INTO THE SOUTHERN ROCKIES WILL PRODUCE RISING
HEIGHTS ON MONDAY AND HIGHS 45 TO 50...AND 50 TO 55 TUESDAY.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
AS OF 100 PM TUESDAY...
A POWERFUL STORM SYSTEM OVER THE LOWER MS VALLEY THIS AFTERNOON WILL
LIFT NE INTO THE TENNESSEE VALLEY BY WEDNESDAY MORNING. A WARM FRONT
ASSOCIATED WITH THIS SYSTEM WILL LIFT NORTH WITH WIDESPREAD RAIN AND
LOW CLOUDINESS SPREADING ACROSS CENTRAL NORTH CAROLINA FROM AROUND
MIDNIGHT TONIGHT THROUGH MID DAY WEDNESDAY. IFR CONDITIONS WILL BE
PREVALENT WITH LIGHT TO MODERATE RAIN. COOL AIR IN PLACE OVER THE
AREA WILL PROVIDE A ZONE OF LOW LEVEL WIND SHEAR WITH WINDS ABOVE
1000 FEET STRENGTHENING LATER TONIGHT INTO MID WEDNESDAY MORNING.
EASTERLY SURFACE WINDS WILL INCREASE RAPIDLY TO 35 TO 40 KNOTS AND
SHIFTING MORE SOUTHEASTERLY.
AS THE STORM LIFTS NE INTO THE MID ATLANTIC WEDNESDAY EVENING...A
STRONG COLD FRONT WILL CROSS CENTRAL NC WEDNESDAY AFTERNOON. AHEAD
OF THIS FRONT...SOUTHERLY WINDS WILL POTENTIALLY GUST TO 30 KTS.
SHOWERS AND A FEW STRONG TO EVEN SEVERE THUNDERSTORMS ARE EXPECTED
FROM MID MORNING IN THE WEST INTO THE EARLY AFTERNOON IN THE
EAST...ENDING BY EARLY WEDNESDAY EVENING.
IMPROVING AVIATION CONDITIONS ARE EXPECTED WEDNESDAY NIGHT WITH VFR
CONDITIONS FROM LATE WEDNESDAY NIGHT THROUGH FRIDAY. SURFACE WINDS
WILL BE INITIALLY BRISK IN WAKE OF THE FRONT WEDNESDAY NIGHT INTO
EARLY THURSDAY WITH GUSTS TO AROUND 30KTS. THE NEXT SHOT AT
ADVERSE AVIATION WEATHER CONDITIONS IS EXPECTED LATE FRIDAY NIGHT
INTO SATURDAY. HIGH PRESSURE WILL BUILD IN ON SUNDAY WITH VFR
CONDITIONS EXPECTED.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...WSS
NEAR TERM...WSS/SMITH
SHORT TERM...MLM
LONG TERM...MLM
AVIATION...MLM
AREA FORECAST DISCUSSION
NWS RALEIGH NC
115 PM EST TUE DEC 25 2012
.SYNOPSIS...
WEAK HIGH PRESSURE WILL EXTEND ACROSS THE REGION TODAY THEN SHIFT
OFFSHORE BY SUNSET. A WARM FRONT AND A DEEPENING LOW PRESSURE SYSTEM
WILL APPROACH FROM THE SOUTHWEST TONIGHT. THE STRONG STORM SYSTEM
AND ACCOMPANYING COLD FRONT WILL SWEEP ACROSS THE AREA WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 945 AM TUESDAY...
WHILE FOG AND LOW CLOUDS HAVE SCOURED ACROSS MUCH OF THE CENTRAL AND
EASTERN CWA...DENSE FOG IS STILL REPORTED IN THE TRIAD...AND TRAFFIC
CAMERAS IN THE AREA SHOW MURKY CONDITIONS ALONG THE I-40 CORRIDOR.
VISIBILITIES HAVE IMPROVED IN RANDOLPH AND DAVIDSON COUNTIES...AND
THERE IS STILL A COUPLE MORE HOURS FOR THE FOG AND STRATUS TO MIX
OUT BEFORE HIGH CLOUDS BEGIN TO POUR BACK IN AHEAD OF THE STORMS
SYSTEM DEVELOPING OVER THE GULF COAST. RAP FORECAST
SOUNDINGS...WHICH SHOW MORE LOW LEVEL MOISTURE THAN WAS OBSERVED ON
THE MORNING RAOBS....SHOW THE LOW CLOUDS SCOURING IN THE TRIAD BY
AROUND NOON. WILL INCREASE CLOUD COVER IN THE NORTHWEST PIEDMONT
AND TRIM OFF A COUPLE DEGREES ON HIGHS SINCE CIRRUS WILL BE STEADILY
INCREASING EVEN AFTER THE LOW CLOUDS BURN OFF. OTHERWISE..THE
FORECAST APPEARS TO BE IN GOOD SHAPE THROUGH 00Z. HIGHS 52-61
NORTHWEST TO SOUTHEAST. -SMITH
TONIGHT...A WARM FRONT WILL DEVELOP ACROSS SC THIS EVENING IN
RESPONSE TO A POWERFUL LOW PRESSURE SYSTEM LIFTING ACROSS THE LOWER
MS VALLEY. SLY WINDS A FEW THOUSAND FEET ABOVE THE SURFACE WILL
ADVECT WARM MOIST AIR UP AND OVER THE COOL STABLE SURFACE LAYER
RESIDING OVER CENTRAL NC. THIS WILL LEAD TO THE DEVELOPMENT OF LOW
CLOUDS...EXPANDING SW-NE IN THE EVENING. ISENTROPIC LIFT WILL
INCREASE LATE THIS EVENING INTO THE OVERNIGHT CAUSING AN EXPANSIVE
AREA OF MODERATE RAINFALL TO DEVELOP. THE GREATEST RAINFALL AMOUNTS
SHOULD FALL OVER THE WESTERN PIEDMONT WHERE BEST LIFT PROJECTED TO
BE FOCUS. TEMPS WILL INITIALLY FALL WITH ONSET OF THE RAIN DUE TO
EVAPORATIVE COOLING IN THE SUB-CLOUD LAYER AFTERWHICH TEMPS WILL
STABILIZE AND MAY ACTUALLY RISE IN THE PRE-DAWN HOURS ACROSS THE
SOUTH AS THE WARM FRONT APPROACHES FROM THE SOUTH. MIN TEMPS NEAR 40
FAR NORTH TO THE MID 40S SOUTH.
&&
.SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/...
AS OF 320 AM TUESDAY...
...AN ACTIVE WEATHER DAY SHAPING UP WEDNESDAY FOR CENTRAL NC WITH A
HIGH LIKELIHOOD OF STRONG TO SEVERE THUNDERSTORMS....
THE SC WARM FRONT PROJECTED TO LIFT NWD ACROSS A LARGE PART OF THE
FORECAST AREA WED AM INTO THE AFTERNOON. THE RAINFALL IN THE WEST
LATE TONIGHT MAY ESTABLISH AN INSITU OR HYBRID CAD AIR MASS OVER THE
NW PIEDMONT. THUS BY MID DAY..MAY SEE A DISTINCT AIR MAS ACROSS THE
REGION WITH COOL STABLE AIR (TEMPS INT EH 40S TO NEAR 50) OVER THE
TRIAD REGION WHILE THE REST OF THE REGION...ESPECIALLY THE SANDHILLS
AND A LARGE PART OF THE COASTAL PLAIN...IN A WARM MOIST UNSTABLE AIR
MASS WITH TEMPS IN THE UPPER 50S AND 60S.
THE STRONG LOW PRESSURE SYSTEM WILL LIFT ENE FROM THE TN VALLEY INTO
THE MID ATLANTIC WED. A STRONG SUB-TROPICAL JET ROUNDING THE BASE OF
THE TROUGH WILL CAUSE THE UPPER TROUGH TO ATTAIN A NEGATIVE TILT
WHICH WILL SPREAD COLDER AIR ALOFT OVER THE WARM MOIST AIR IN THE
LOWER LAYERS OF THE ATMOSPHERE. THIS WILL RESULT IN AN UNSTABLE
ATMOSPHERE ACROSS CENTRAL NC WITH MID LEVEL LAPSE RATES UP TO 7.5
DEGREES. IN ADDITION...THE LOW PRESSURE SYSTEM WILL SPAWN A STRONG
LOW LEVEL JET THAT WILL LIFT ACROSS THE REGION IN THE AFTERNOON.
THIS STRONG LLJ INTERACTING WITH SURFACE BOUNDARY/WARM FRONT WILL
GREATLY ENHANCE THE LOW LEVEL HELICITY SUPPORTIVE OF STORMS WITH
ROTATING UPDRAFTS. THUS...WITH A STRONG WIND FIELD IN PLACE
INTERACTING WITH AN INCREASINGLY MOIST AND UNSTABLE (FOR WINTER) AIR
MASS...STRONG TO SEVERE STORMS APPEAR QUITE LIKELY.
AT THIS TIME...IT APPEARS A NEAR SOLID LINE OF STORMS WILL OCCUR
AHEAD OF A STRONG COLD FRONT THAT WILL CROSS THE REGION IN THE
AFTERNOON. OUT AHEAD OF THE LINE...THE AIR MASS WILL BE SUPPORTIVE
OF A FEW SUPERCELL THUNDERSTORMS. WHILE THE PRIMARY SEVERE WEATHER
THREAT WILL BE DAMAGING STRAIGHT-LINE WINDS ASSOCIATED WITH THE LINE
OF CONVECTION...THE ISOLATED THUNDERSTORMS THAT OCCUR AHEAD OF THE
LINE WILL HAVE THE POTENTIAL TO PRODUCE A FEW TORNADOES.
CURRENT INDICATIONS SUGGEST THAT THE SEVERE WEATHER THREAT MAY
START AS EARLY 10-11 AM IN THE SOUTHERN COUNTIES THEN EXPAND N-NE
TO COVER THE REST OF THE REGION DURING THE AFTERNOON HOURS AS A
SURFACE LOW MOVES ALONG THE NWD MOVING WARM FRONT. THE SEVERE
WEATHER THREAT BEGINS TO DECREASE IN THE WEST BY LATE AFTERNOON AND
IN THE EAST SHORTLY AFTER SUNSET.
WEDNESDAY NIGHT...THE SURFACE COLD FRONT WILL EXIT THE REGION EARLY.
W-NW WINDS BEHIND THE FRONT WILL BE QUITE STRONG WITH GUSTS 25-30MPH
PROBABLE. THESE WINDS WILL ALSO USHER MUCH COOLER AND DRIER AIR INTO
THE REGION. THIS DRIER AIR SHOULD QUICKLY DISSIPATE CLOUD COVERAGE
ACROSS THE AREA...LEADING TO CLEAR SKIES BY MIDNIGHT. MUCH COOLER
WITH MIN TEMPS IN THE LOW-MID 30S.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 255 AM TUESDAY...
FOR THURSDAY THROUGH FRIDAY NIGHT: THE DEPARTING STORM IS EXPECTED
TO BE CENTERED JUST OFF NYC THURSDAY MORNING. THE MSLP GRADIENT OVER
NC REMAINS SUFFICIENTLY STRONG FOR CONTINUED BRISK WINDS...
SUSTAINED OVER 15 MPH AND GUSTS UP TO 30-35 MPH THROUGH AT LEAST THE
EARLY PART OF THE AFTERNOON. HIGHLY STABLE AND WARMING MID LEVELS
WITH 120-150 METER HEIGHT RISES SHOULD STAVE OFF MOST CLOUDS...
ALTHOUGH A FEW FLAT STRATOCU ARE LIKELY IN THE AFTERNOON AS THE
REMAINING BOUNDARY LAYER MOISTURE GETS TRAPPED BENEATH THE
SUBSIDENCE INVERSION ALOFT... AND VERY HIGH THIN CLOUDS WILL STREAK
OVER THE AREA AS WELL WITH AN ELONGATED 125+ KT JET CORE PASSING
OVERHEAD. THE SHALLOW MIXED LAYER SUPPORTS HIGHS THURSDAY OF
46-52... VERY CLOSE TO EXISTING FORECAST. GOOD RADIATIONAL COOLING
THURSDAY NIGHT AS SURFACE HIGH PRESSURE DRIFTS OVERHEAD WITH FAIR TO
MOSTLY CLEAR SKIES. LOWS 26-30. THE HIGH SLIPS OFF THE SOUTHEAST
COAST BY LATE FRIDAY... AND HIGH CLOUDS WILL BE INCREASING SLOWLY AS
THE ANTICYCLONIC MID LEVEL FLOW FLATTENS TO SOUTHWESTERLY AND
STRENGTHENS... IN ADVANCE OF OUR NEXT STORM SYSTEM DIGGING OVER THE
SRN PLAINS. WITH LITTLE CHANGE IN AIR MASS OR VERTICAL THERMAL
STRUCTURE... EXPECT HIGHS TO BE MINIMALLY HIGHER FRIDAY... 48-53.
SKIES WILL TREND TO CLOUDY SOUTH TO NORTH AS THE LONGWAVE TROUGH
AXIS SWINGS TOWARD THE MISS VALLEY... RESULTING IN THICKENING AND
LOWERING MID CLOUDS. GFS FORECAST SOUNDINGS SHOW THE SURFACE-BASED
STABLE POOL HOLDING FIRM DESPITE THE INCREASING SOUTHERLY FLOW AND
MOIST UPGLIDE FROM 950 MB UP (PARTICULARLY 285K-290K)... DRAWING LOW
LEVEL ATLANTIC MOISTURE INTO THE SOUTHERN AND EASTERN PORTIONS OF
THE FORECAST AREA... AND THIS FLOW WILL INCREASE TOWARD MORNING AS
SURFACE LOW PRESSURE IS EXPECTED TO STRENGTHEN OVER THE GULF COAST
BETWEEN NEW ORLEANS AND MOBILE. THE LATEST GFS/ECMWF RUNS SUPPORT
DELAYING THE DEEP LAYER LIFT AND THE RESULTING CHANCE OF MEASURABLE
RAIN UNTIL CLOSE TO SUNRISE SATURDAY MORNING... SO WILL SLOW THE
ARRIVAL OF RAIN CHANCES BY A FEW HOURS LATE FRIDAY NIGHT. LOWS
30-38.
FOR SATURDAY/SATURDAY NIGHT: ANOTHER STRONG STORM SYSTEM WILL AFFECT
NC EARLY IN THE WEEKEND. THE LATEST ECMWF INITIALIZED AT 00Z
SUPPORTS AND EXTENDS RECENT MODEL TRENDS TOWARD A MILLER TYPE-A
(SINGLE-LOW) CYCLOGENESIS PATTERN... WITH THE SURFACE LOW MOVING
EASTWARD ACROSS SRN GA BEFORE TRACKING UP THE COAST OF THE
CAROLINAS. MOISTURE SHOULD BE PLENTIFUL WITH FEEDS FROM BOTH THE
ATLANTIC AND GULF... AND FORCING FOR ASCENT IS LIKELY TO BE RAPIDLY
STRENGTHENING SATURDAY. 12-HR PROJECTED MID LEVEL HEIGHT FALLS ARE
150 M TO AS MUCH AS 200 M OVER NC IN CONJUNCTION WITH INCREASING
(BUT NOT OVERLY INTENSE) UPPER DIVERGENCE AND STRENGTHENING LOW
LEVEL MASS CONVERGENCE MAINLY IN OUR SOUTH AND EAST. WILL MAINTAIN
SOME CAUTION BUT DECENT MODEL AGREEMENT WITHIN THIS ACTIVE PATTERN
SUPPORTS AN UPTICK OF RAIN CHANCES ESPECIALLY IN THE SOUTH AND EAST.
HIGHS FROM 45 IN THE COOL STABLE AIR IN THE NORTHWEST CWA RANGING TO
56 SOUTHEAST. RAIN SHOULD TAPER TO SPOTTY DRIZZLE GIVEN THE DRYING
ALOFT SATURDAY EVENING... BEFORE ENDING ENTIRELY AFTER MIDNIGHT.
LOWS 29-35.
FOR SUNDAY/MONDAY: QUIET WEATHER BEHIND THIS SYSTEM WITH SURFACE
HIGH PRESSURE BUILDING OVERHEAD FROM THE WEST. THE AIR MASS SHOULD
BE SOMEWHAT MODIFIED PARTICULARLY WITH HEIGHTS RISING QUICKLY ALOFT
AS NEW LONGWAVE TROUGHING DIGS OVER THE ROCKIES. EXPECT BELOW NORMAL
TEMPS SUNDAY TRENDING UP CLOSER TO NORMAL MONDAY... WITH DRY
WEATHER. -GIH
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
AS OF 100 PM TUESDAY...
A POWERFUL STORM SYSTEM OVER THE LOWER MS VALLEY THIS AFTERNOON WILL
LIFT NE INTO THE TENNESSEE VALLEY BY WEDNESDAY MORNING. A WARM FRONT
ASSOCIATED WITH THIS SYSTEM WILL LIFT NORTH WITH WIDESPREAD RAIN AND
LOW CLOUDINESS SPREADING ACROSS CENTRAL NORTH CAROLINA FROM AROUND
MIDNIGHT TONIGHT THROUGH MID DAY WEDNESDAY. IFR CONDITIONS WILL BE
PREVALENT WITH LIGHT TO MODERATE RAIN. COOL AIR IN PLACE OVER THE
AREA WILL PROVIDE A ZONE OF LOW LEVEL WIND SHEAR WITH WINDS ABOVE
1000 FEET STRENGTHENING LATER TONIGHT INTO MID WEDNESDAY MORNING.
EASTERLY SURFACE WINDS WILL INCREASE RAPIDLY TO 35 TO 40 KNOTS AND
SHIFTING MORE SOUTHEASTERLY.
AS THE STORM LIFTS NE INTO THE MID ATLANTIC WEDNESDAY EVENING...A
STRONG COLD FRONT WILL CROSS CENTRAL NC WEDNESDAY AFTERNOON. AHEAD
OF THIS FRONT...SOUTHERLY WINDS WILL POTENTIALLY GUST TO 30 KTS.
SHOWERS AND A FEW STRONG TO EVEN SEVERE THUNDERSTORMS ARE EXPECTED
FROM MID MORNING IN THE WEST INTO THE EARLY AFTERNOON IN THE
EAST...ENDING BY EARLY WEDNESDAY EVENING.
IMPROVING AVIATION CONDITIONS ARE EXPECTED WEDNESDAY NIGHT WITH VFR
CONDITIONS FROM LATE WEDNESDAY NIGHT THROUGH FRIDAY. SURFACE WINDS
WILL BE INITIALLY BRISK IN WAKE OF THE FRONT WEDNESDAY NIGHT INTO
EARLY THURSDAY WITH GUSTS TO AROUND 30KTS. THE NEXT SHOT AT
ADVERSE AVIATION WEATHER CONDITIONS IS EXPECTED LATE FRIDAY NIGHT
INTO SATURDAY. HIGH PRESSURE WILL BUILD IN ON SUNDAY WITH VFR
CONDITIONS EXPECTED.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...WSS
NEAR TERM...WSS/SMITH
SHORT TERM...WSS
LONG TERM...HARTFIELD
AVIATION...MLM
AREA FORECAST DISCUSSION
NWS RALEIGH NC
945 AM EST TUE DEC 25 2012
.SYNOPSIS...
WEAK HIGH PRESSURE WILL EXTEND ACROSS THE REGION TODAY THEN SHIFT
OFFSHORE BY SUNSET. A WARM FRONT AND A DEEPENING LOW PRESSURE SYSTEM
WILL APPROACH FROM THE SOUTHWEST TONIGHT. THE STRONG STORM SYSTEM
AND ACCOMPANYING COLD FRONT WILL SWEEP ACROSS THE AREA WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 945 AM TUESDAY...
WHILE FOG AND LOW CLOUDS HAVE SCOURED ACROSS MUCH OF THE CENTRAL AND
EASTERN CWA...DENSE FOG IS STILL REPORTED IN THE TRIAD...AND TRAFFIC
CAMERAS IN THE AREA SHOW MURKY CONDITIONS ALONG THE I-40 CORRIDOR.
VISIBILITIES HAVE IMPROVED IN RANDOLPH AND DAVIDSON COUNTIES...AND
THERE IS STILL A COUPLE MORE HOURS FOR THE FOG AND STRATUS TO MIX
OUT BEFORE HIGH CLOUDS BEGIN TO POUR BACK IN AHEAD OF THE STORMS
SYSTEM DEVELOPING OVER THE GULF COAST. RAP FORECAST
SOUNDINGS...WHICH SHOW MORE LOW LEVEL MOISTURE THAN WAS OBSERVED ON
THE MORNING RAOBS....SHOW THE LOW CLOUDS SCOURING IN THE TRIAD BY
AROUND NOON. WILL INCREASE CLOUD COVER IN THE NORTHWEST PIEDMONT
AND TRIM OFF A COUPLE DEGREES ON HIGHS SINCE CIRRUS WILL BE STEADILY
INCREASING EVEN AFTER THE LOW CLOUDS BURN OFF. OTHERWISE..THE
FORECAST APPEARS TO BE IN GOOD SHAPE THROUGH 00Z. HIGHS 52-61
NORTHWEST TO SOUTHEAST. -SMITH
TONIGHT...A WARM FRONT WILL DEVELOP ACROSS SC THIS EVENING IN
RESPONSE TO A POWERFUL LOW PRESSURE SYSTEM LIFTING ACROSS THE LOWER
MS VALLEY. SLY WINDS A FEW THOUSAND FEET ABOVE THE SURFACE WILL
ADVECT WARM MOIST AIR UP AND OVER THE COOL STABLE SURFACE LAYER
RESIDING OVER CENTRAL NC. THIS WILL LEAD TO THE DEVELOPMENT OF LOW
CLOUDS...EXPANDING SW-NE IN THE EVENING. ISENTROPIC LIFT WILL
INCREASE LATE THIS EVENING INTO THE OVERNIGHT CAUSING AN EXPANSIVE
AREA OF MODERATE RAINFALL TO DEVELOP. THE GREATEST RAINFALL AMOUNTS
SHOULD FALL OVER THE WESTERN PIEDMONT WHERE BEST LIFT PROJECTED TO
BE FOCUS. TEMPS WILL INITIALLY FALL WITH ONSET OF THE RAIN DUE TO
EVAPORATIVE COOLING IN THE SUB-CLOUD LAYER AFTERWHICH TEMPS WILL
STABILIZE AND MAY ACTUALLY RISE IN THE PRE-DAWN HOURS ACROSS THE
SOUTH AS THE WARM FRONT APPROACHES FROM THE SOUTH. MIN TEMPS NEAR 40
FAR NORTH TO THE MID 40S SOUTH.
&&
.SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/...
AS OF 320 AM TUESDAY...
...AN ACTIVE WEATHER DAY SHAPING UP WEDNESDAY FOR CENTRAL NC WITH A
HIGH LIKELIHOOD OF STRONG TO SEVERE THUNDERSTORMS....
THE SC WARM FRONT PROJECTED TO LIFT NWD ACROSS A LARGE PART OF THE
FORECAST AREA WED AM INTO THE AFTERNOON. THE RAINFALL IN THE WEST
LATE TONIGHT MAY ESTABLISH AN INSITU OR HYBRID CAD AIR MASS OVER THE
NW PIEDMONT. THUS BY MID DAY..MAY SEE A DISTINCT AIR MAS ACROSS THE
REGION WITH COOL STABLE AIR (TEMPS INT EH 40S TO NEAR 50) OVER THE
TRIAD REGION WHILE THE REST OF THE REGION...ESPECIALLY THE SANDHILLS
AND A LARGE PART OF THE COASTAL PLAIN...IN A WARM MOIST UNSTABLE AIR
MASS WITH TEMPS IN THE UPPER 50S AND 60S.
THE STRONG LOW PRESSURE SYSTEM WILL LIFT ENE FROM THE TN VALLEY INTO
THE MID ATLANTIC WED. A STRONG SUB-TROPICAL JET ROUNDING THE BASE OF
THE TROUGH WILL CAUSE THE UPPER TROUGH TO ATTAIN A NEGATIVE TILT
WHICH WILL SPREAD COLDER AIR ALOFT OVER THE WARM MOIST AIR IN THE
LOWER LAYERS OF THE ATMOSPHERE. THIS WILL RESULT IN AN UNSTABLE
ATMOSPHERE ACROSS CENTRAL NC WITH MID LEVEL LAPSE RATES UP TO 7.5
DEGREES. IN ADDITION...THE LOW PRESSURE SYSTEM WILL SPAWN A STRONG
LOW LEVEL JET THAT WILL LIFT ACROSS THE REGION IN THE AFTERNOON.
THIS STRONG LLJ INTERACTING WITH SURFACE BOUNDARY/WARM FRONT WILL
GREATLY ENHANCE THE LOW LEVEL HELICITY SUPPORTIVE OF STORMS WITH
ROTATING UPDRAFTS. THUS...WITH A STRONG WIND FIELD IN PLACE
INTERACTING WITH AN INCREASINGLY MOIST AND UNSTABLE (FOR WINTER) AIR
MASS...STRONG TO SEVERE STORMS APPEAR QUITE LIKELY.
AT THIS TIME...IT APPEARS A NEAR SOLID LINE OF STORMS WILL OCCUR
AHEAD OF A STRONG COLD FRONT THAT WILL CROSS THE REGION IN THE
AFTERNOON. OUT AHEAD OF THE LINE...THE AIR MASS WILL BE SUPPORTIVE
OF A FEW SUPERCELL THUNDERSTORMS. WHILE THE PRIMARY SEVERE WEATHER
THREAT WILL BE DAMAGING STRAIGHT-LINE WINDS ASSOCIATED WITH THE LINE
OF CONVECTION...THE ISOLATED THUNDERSTORMS THAT OCCUR AHEAD OF THE
LINE WILL HAVE THE POTENTIAL TO PRODUCE A FEW TORNADOES.
CURRENT INDICATIONS SUGGEST THAT THE SEVERE WEATHER THREAT MAY
START AS EARLY 10-11 AM IN THE SOUTHERN COUNTIES THEN EXPAND N-NE
TO COVER THE REST OF THE REGION DURING THE AFTERNOON HOURS AS A
SURFACE LOW MOVES ALONG THE NWD MOVING WARM FRONT. THE SEVERE
WEATHER THREAT BEGINS TO DECREASE IN THE WEST BY LATE AFTERNOON AND
IN THE EAST SHORTLY AFTER SUNSET.
WEDNESDAY NIGHT...THE SURFACE COLD FRONT WILL EXIT THE REGION EARLY.
W-NW WINDS BEHIND THE FRONT WILL BE QUITE STRONG WITH GUSTS 25-30MPH
PROBABLE. THESE WINDS WILL ALSO USHER MUCH COOLER AND DRIER AIR INTO
THE REGION. THIS DRIER AIR SHOULD QUICKLY DISSIPATE CLOUD COVERAGE
ACROSS THE AREA...LEADING TO CLEAR SKIES BY MIDNIGHT. MUCH COOLER
WITH MIN TEMPS IN THE LOW-MID 30S.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 255 AM TUESDAY...
FOR THURSDAY THROUGH FRIDAY NIGHT: THE DEPARTING STORM IS EXPECTED
TO BE CENTERED JUST OFF NYC THURSDAY MORNING. THE MSLP GRADIENT OVER
NC REMAINS SUFFICIENTLY STRONG FOR CONTINUED BRISK WINDS...
SUSTAINED OVER 15 MPH AND GUSTS UP TO 30-35 MPH THROUGH AT LEAST THE
EARLY PART OF THE AFTERNOON. HIGHLY STABLE AND WARMING MID LEVELS
WITH 120-150 METER HEIGHT RISES SHOULD STAVE OFF MOST CLOUDS...
ALTHOUGH A FEW FLAT STRATOCU ARE LIKELY IN THE AFTERNOON AS THE
REMAINING BOUNDARY LAYER MOISTURE GETS TRAPPED BENEATH THE
SUBSIDENCE INVERSION ALOFT... AND VERY HIGH THIN CLOUDS WILL STREAK
OVER THE AREA AS WELL WITH AN ELONGATED 125+ KT JET CORE PASSING
OVERHEAD. THE SHALLOW MIXED LAYER SUPPORTS HIGHS THURSDAY OF
46-52... VERY CLOSE TO EXISTING FORECAST. GOOD RADIATIONAL COOLING
THURSDAY NIGHT AS SURFACE HIGH PRESSURE DRIFTS OVERHEAD WITH FAIR TO
MOSTLY CLEAR SKIES. LOWS 26-30. THE HIGH SLIPS OFF THE SOUTHEAST
COAST BY LATE FRIDAY... AND HIGH CLOUDS WILL BE INCREASING SLOWLY AS
THE ANTICYCLONIC MID LEVEL FLOW FLATTENS TO SOUTHWESTERLY AND
STRENGTHENS... IN ADVANCE OF OUR NEXT STORM SYSTEM DIGGING OVER THE
SRN PLAINS. WITH LITTLE CHANGE IN AIR MASS OR VERTICAL THERMAL
STRUCTURE... EXPECT HIGHS TO BE MINIMALLY HIGHER FRIDAY... 48-53.
SKIES WILL TREND TO CLOUDY SOUTH TO NORTH AS THE LONGWAVE TROUGH
AXIS SWINGS TOWARD THE MISS VALLEY... RESULTING IN THICKENING AND
LOWERING MID CLOUDS. GFS FORECAST SOUNDINGS SHOW THE SURFACE-BASED
STABLE POOL HOLDING FIRM DESPITE THE INCREASING SOUTHERLY FLOW AND
MOIST UPGLIDE FROM 950 MB UP (PARTICULARLY 285K-290K)... DRAWING LOW
LEVEL ATLANTIC MOISTURE INTO THE SOUTHERN AND EASTERN PORTIONS OF
THE FORECAST AREA... AND THIS FLOW WILL INCREASE TOWARD MORNING AS
SURFACE LOW PRESSURE IS EXPECTED TO STRENGTHEN OVER THE GULF COAST
BETWEEN NEW ORLEANS AND MOBILE. THE LATEST GFS/ECMWF RUNS SUPPORT
DELAYING THE DEEP LAYER LIFT AND THE RESULTING CHANCE OF MEASURABLE
RAIN UNTIL CLOSE TO SUNRISE SATURDAY MORNING... SO WILL SLOW THE
ARRIVAL OF RAIN CHANCES BY A FEW HOURS LATE FRIDAY NIGHT. LOWS
30-38.
FOR SATURDAY/SATURDAY NIGHT: ANOTHER STRONG STORM SYSTEM WILL AFFECT
NC EARLY IN THE WEEKEND. THE LATEST ECMWF INITIALIZED AT 00Z
SUPPORTS AND EXTENDS RECENT MODEL TRENDS TOWARD A MILLER TYPE-A
(SINGLE-LOW) CYCLOGENESIS PATTERN... WITH THE SURFACE LOW MOVING
EASTWARD ACROSS SRN GA BEFORE TRACKING UP THE COAST OF THE
CAROLINAS. MOISTURE SHOULD BE PLENTIFUL WITH FEEDS FROM BOTH THE
ATLANTIC AND GULF... AND FORCING FOR ASCENT IS LIKELY TO BE RAPIDLY
STRENGTHENING SATURDAY. 12-HR PROJECTED MID LEVEL HEIGHT FALLS ARE
150 M TO AS MUCH AS 200 M OVER NC IN CONJUNCTION WITH INCREASING
(BUT NOT OVERLY INTENSE) UPPER DIVERGENCE AND STRENGTHENING LOW
LEVEL MASS CONVERGENCE MAINLY IN OUR SOUTH AND EAST. WILL MAINTAIN
SOME CAUTION BUT DECENT MODEL AGREEMENT WITHIN THIS ACTIVE PATTERN
SUPPORTS AN UPTICK OF RAIN CHANCES ESPECIALLY IN THE SOUTH AND EAST.
HIGHS FROM 45 IN THE COOL STABLE AIR IN THE NORTHWEST CWA RANGING TO
56 SOUTHEAST. RAIN SHOULD TAPER TO SPOTTY DRIZZLE GIVEN THE DRYING
ALOFT SATURDAY EVENING... BEFORE ENDING ENTIRELY AFTER MIDNIGHT.
LOWS 29-35.
FOR SUNDAY/MONDAY: QUIET WEATHER BEHIND THIS SYSTEM WITH SURFACE
HIGH PRESSURE BUILDING OVERHEAD FROM THE WEST. THE AIR MASS SHOULD
BE SOMEWHAT MODIFIED PARTICULARLY WITH HEIGHTS RISING QUICKLY ALOFT
AS NEW LONGWAVE TROUGHING DIGS OVER THE ROCKIES. EXPECT BELOW NORMAL
TEMPS SUNDAY TRENDING UP CLOSER TO NORMAL MONDAY... WITH DRY
WEATHER. -GIH
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
AS OF 645 AM TUESDAY...
MERRY CHRISTMAS!
WIDESPREAD MVFR/IFR CEILINGS WILL GRADUALLY LIFT AND DISSIPATE
THROUGH 10 AM AS DRIER MORE STABLE AIR OVERSPREADS THE REGION FROM
THE NE. LOCALIZED THICK FOG WITH VISIBILITIES AT OR BELOW A HALF
MILE ARE CONFINED TO SECTIONS OF THE WESTERN PIEDMONT AND SANDHILLS.
THE FOG WILL ALSO LIFT AND DISSIPATE PRIOR TO 9 AM.
FOR THE REMINDER OF CHRISTMAS MORNING INTO CHRISTMAS AFTERNOON
EXPECT VFR CONDITIONS AND SURFACE WINDS GRADUALLY VEERING FROM A NNE
DIRECTION IN THE MORNING TO AN ELY COMPONENT BY MID AFTERNOON.
A POWERFUL STORM SYSTEM OVER THE LOWER MS VALLEY LATER TODAY AND
TONIGHT WILL LIFT NE INTO THE TN VALLEY BY WEDNESDAY MORNING. THIS
SYSTEM WILL CAUSE A WARM FRONT TO DEVELOP OVER SC BY WEDNESDAY
MORNING. SLY FLOW ABOVE THIS FEATURE WILL CAUSE WIDESPREAD RAIN AND
LOW CLOUDS TO ENVELOPE CENTRAL NC FROM THE SW LATE TONIGHT INTO
WEDNESDAY MORNING. THIS WILL LEAD TO AN EXTENDED PERIOD OF MVFR/IFR
CONDITIONS. WHILE NEAR SURFACE WINDS EARLY WEDNESDAY MORNING WILL BE
ELY...WINDS AT AND ABOVE 3000FT WILL BE SLY AND INCREASING TO NEAR
35KTS. THIS SLY WINDS WILL GRADUALLY LOWER TO NEAR 1500FT BY
MID-LATE WEDNESDAY MORNING...POSSIBLY CREATING LLWS CONDITIONS UNTIL
EARLY AFTERNOON.
AS THE STORM SYSTEM LIFTS ENE INTO THE MID ATLANTIC BY WEDNESDAY
EVENING...A STRONG COLD FRONT WILL CROSS CENTRAL NC WEDNESDAY
AFTERNOON. AHEAD OF THIS FRONT...EXPECT GUSTY SLY WINDS WITH GUSTS
NEAR 30 KTS POSSIBLE. SHOWERS AND A FEW STRONG-SEVERE STORMS WILL
CROSS THE REGION WEDNESDAY AFTERNOON...ENDING BY EARLY WEDNESDAY
EVENING.
IMPROVING AVIATION CONDITIONS EXPECTED WEDNESDAY NIGHT WITH VFR
CONDITIONS ANTICIPATED LATE WEDNESDAY NIGHT THROUGH FRIDAY. SURFACE
WINDS WILL BE BRISK IN WAKE OF THE FRONT WEDNESDAY NIGHT INTO EARLY
THURSDAY WITH GUSTS AROUND 30KTS LIKELY. THE NEXT SHOT AT ADVERSE
AVIATION WEATHER CONDITIONS IS EXPECTED LATE FRIDAY NIGHT INTO
SATURDAY.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...WSS
NEAR TERM...WSS/SMITH
SHORT TERM...WSS
LONG TERM...HARTFIELD
AVIATION...WSS
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
633 PM EST WED DEC 26 2012
.SYNOPSIS...
POTENT WINTER STORM WILL RELAX ITS INFLUENCE ON THE OHIO VALLEY
THROUGH TONIGHT AND BE REPLACED BY WEAK HIGH PRESSURE ON THURSDAY.
NEXT WEAK TROUGH OF LOW PRESSURE WILL MOVE INTO THE AREA FRIDAY
NIGHT WITH THE NEXT CHANCE OF SNOW...ALBEIT LIGHT...AND FOCUSED ON
AREAS NEAR THE OHIO RIVER. TEMPERATURES OVER THE NEXT FEW DAYS
WILL REMAIN SEASONABLY COLD. IN THE LONGER TERM...NO MAJOR WEATHER
SYSTEMS ARE ON TAP FOR THE AREA.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
HAVE DOWNGRADED ALL WARNINGS TO ADVISORIES FOR MUCH OF THE AREA AS
IMPACTS OF WINTER STORM ARE BEGINNING TO RELAX. HAVE SEEN A
SLOW/STEADY DECREASE IN WINDS THROUGH THE AFTERNOON /THOUGH STILL
20-25KTS ACROSS WRN OH/ERN IND/...AND PRIMARY SNOW BAND THAT HAD
DEPOSITED 6-9 INCHES OF SNOW FROM SERN IND INTO WCNTL OH HAS
LARGELY BROKEN DOWN AND DECREASED IN INTENSITY. LARGER SYNOPTIC
BAND OF SNOW ACROSS MICHIGAN INTO NRN IND MAY WRAP E-NE INTO FAR
NRN FORECAST AREA THIS EVENING BUT LATEST RAP FORCING /FGEN/
DIAGNOSTICS INDICATE THIS WILL BEGIN TO BREAK DOWN AS WELL.
SO OVERALL...EXPECT BROKEN BANDS OF SNOW /MIXED WITH OR JUST PLAIN
RAIN ALONG AND SOUTH OF OHIO RIVER/ TO CONTINUE TO PROGRESS E-NE
ACROSS THE FORECAST AREA AS TRANSFER OF ENERGY TO DEEPER SFC LOW
ALONG THE ERN SEABOARD CONTINUES. STILL SEEING AN OCCASIONAL
REPORT OF FZDZ/FZRA/FZRAPL FROM TIME TO TIME...AND GIVEN CRITICAL
THERMAL STRUCTURE ON RAP FORECAST SOUNDINGS...SEE NO REASON WHY
THIS WON/T CONTINUE NEXT 1-2 HOURS...BEFORE COOLING ALOFT WILL
YIELD MORE OF A WIDESPREAD -SN SCENARIO FOR MOST OF THE ADVISORY
AREA. DON/T EXPECT MUCH MORE THAN AN ADDITIONAL INCH OF SNOW FOR
ANYONE...THOUGH AREAS NORTH/EAST OF COLUMBUS METRO STAND THE
BETTER CHANCES FOR PERHAPS A LITTLE MORE THAN AN INCH. ANY BLOWING
SNOW SHOULD DIMINISH EARLY TO MID EVENING...AND EXPECT TEMPS TO
ONLY FALL BACK INTO THE MID 20S...WHICH SHOULD AID IN ROAD
TREATMENTS/IMPROVEMENTS AS THE NIGHT WEARS ON.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
THURSDAY THROUGH FRIDAY ARE LARGELY A QUIET FORECAST...THOUGH
RESIDUAL/STUBBORN LOW LEVEL MOISTURE MAY CONTINUE TO YIELD
FLURRIES ESPECIALLY IN CNTL OHIO. TEMPERATURES THURSDAY NIGHT A
TRICKY POINT...GIVEN FRESH/DEEP SNOW COVER IN WRN/NRN PARTS OF
FORECAST AREA. APPRECIABLE CLEARING WILL SEND THOSE TEMPS INTO A
NOSEDIVE...AND COULD YIELD A SINGLE DIGIT OR TWO IF CLEARING IS
SUBSTANTIAL. NOT GOING THAT CLEAR ON SKY RIGHT NOW - SO HAVE KEPT
TEMPS NEAR/JUST BELOW STATISTICAL MOS GUIDANCE.
FRIDAY NIGHT A WEAK/POSITIVELY TILTED TROUGH /DISCUSSED BELOW IN
.LONG TERM SECTION/ WILL RACE NORTHEAST FROM THE SRN PLAINS...AND
INDUCE WEAK SFC LOW DEVELOPMENT IN THE SOUTHEAST. INVERTED TROUGH
AND ATTENDANT WEAK FORCING WILL SPREAD NORTHEAST ALONG WITH A
RATHER SUBSTANTIAL PLUME OF MOISTURE TO BRING RAIN/SNOW CHANCE
BACK INTO THE AREA...ESP NEAR/SOUTH OF THE OHIO RIVER. SIDED WITH
26.12Z ECMWF FORCING AND THERMAL CHARACTERISTICS FOR THIS FORECAST
THOUGH ADMITTEDLY 26.12Z GFS NOT TOO FAR OFF. SEE BELOW FOR MORE DETAILS.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
A BROAD TROUGH OVER THE CENTRAL CONUS WILL SLIDE ACROSS THE OHIO
VALLEY ON SATURDAY. THE 26.12Z GFS/EUROPEAN/CANADIAN RUNS HAVE COME
INTO PRETTY GOOD AGREEMENT WITH REGARD TO THE TIMING OF THIS FEATURE
AND ITS ASSOCIATED MID LEVEL ENERGY AS IT PROGRESSES EASTWARD ACROSS
THE AREA. SOME LIGHT SNOW WILL BE POSSIBLE...ESPECIALLY ACROSS THE
SOUTHEASTERN CWA. COOLER AIR WILL SETTLE INTO THE REGION FOR THE
WEEKEND WITH HIGHS SATURDAY IN THE LOWER TO MIDDLE 30S...HIGHS
SUNDAY IN THE MID 20S TO LOWER 30S...AND LOWS BOTH NIGHTS IN THE
TEENS TO LOWER 20S.
CLOUDS WILL BEGIN TO DECREASE A BIT ON SUNDAY AS HIGH PRESSURE OVER
THE LOWER MS VALLEY MOVES NORTHEAST INTO THE REGION. THIS SYSTEM
WILL PROVIDE QUIET WEATHER THROUGH MONDAY MORNING. THE GFS AND ECMWF
THEN BEGIN TO DIVERGE SIGNIFICANTLY FOR THE REMAINDER OF THE
EXTENDED PERIOD...AND GEFS ENSEMBLE CLUSTERS SHOW CONSIDERABLE
SPREAD. A COLD FRONT IS PROGGED TO PUSH THROUGH THE AREA LATE MONDAY
NIGHT INTO TUESDAY...BRINGING THE NEXT CHANCE FOR SOME PRECIP.
FORECAST SOUNDINGS INDICATE THE ONSLAUGHT OF PRECIPITATION MONDAY
EVENING MAY BEGIN AS RAIN...SNOW...OR A MIX SOUTH OF THE OHIO RIVER
BEFORE COLDER TEMPERATURES CHANGE IT TO LIGHT SNOW. ELSEWHERE...
EXPECT JUST CHANCE/SLIGHT CHANCE FOR LIGHT SNOW AT TIMES THROUGH
WEDNESDAY.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
WRAPAROUND LIGHT SNOW ACROSS OUR TERMINALS ASSOCIATED WITH LOW
PRESSURE MOVING NORTHEAST INTO WEST VIRGINIA WILL CONTINUE FOR THE
NEXT SEVERAL HOURS. THE TREND WILL BE FOR THE LIGHT SNOW CURRENTLY
REDUCING VSBYS TO DECREASE IN COVERAGE AND SHIFT
EASTWARD...LEAVING THE TERMINALS WITH MAINLY MVFR OR VFR VSBYS BY
MIDNIGHT. IFR WITH A FEW POCKETS OF MVFR CIGS WILL CONTINUE UNTIL
AFTER SUNRISE. AS THE LOW SHIFTS WELL NORTHEAST OF OUR AREA DURING
THE LATE MORNING...CIGS ARE EXPECTED TO RISE TO MVFR. AFTER
SUNSET THURSDAY...THE REMAINING MVFR CLOUD DECK WILL LIKELY LOWER
BACK TO IFR. SOME FOG/MIST DEVELOPMENT WILL ALSO BECOME POSSIBLE AT
THAT TIME.
OUTLOOK...MVFR/IFR CEILINGS AND VISIBILITIES POSSIBLE SATURDAY
INTO SATURDAY NIGHT.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR OHZ026-
034-035-042>046-051>056-060>065-070>074-077>080.
KY...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR
KYZ089>099.
IN...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR INZ050-
058-059-066-073>075-080.
&&
$$
SYNOPSIS...BINAU
NEAR TERM...BINAU
SHORT TERM...BINAU
LONG TERM...KURZ
AVIATION...LATTO
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
454 AM EST TUE DEC 25 2012
.SYNOPSIS...
LOW PRESSURE WILL TRACK FROM TEXAS TODAY AND SKIM THE SOUTHERN
OHIO VALLEY AS IT MOVES NORTHEAST ON WEDNESDAY. HIGH PRESSURE OVER
THE MIDWEST WILL BUILD FOR THE LATTER PART OF THE WEEK AND SETTLE
OVER THE OHIO VALLEY ON FRIDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
RADAR RETURNS HAVE NOT MATERIALIZED INTO ANY ADDITIONAL FREEZING
DRIZZLE EARLY THIS MORNING OVER THE NORTHWEST PORTIONS OF CWA.
EXPECT CLOUDY SKIES TO SEE SOME BREAKS THIS AFTERNOON AND THEN
HAVE THE SOUTHWESTERN SYSTEM BEGIN TO OVERSPREAD THE REGION LATE
TODAY. TEMPERATURES WILL RISE INTO THE MID AND UPPER 30S FOR MUCH
OF THE REGION. AREAS SOUTH OF THE OHIO COULD TOP OUT IN THE LOW
40S TODAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
PRECIPITATION SHIELD WILL OVERSPREAD THE OHIO VALLEY TONIGHT.
MODELS AND NUMERICAL GUIDANCE WERE ALL 2-3 DEGREES COOLER ON LOW
TEMPERATURES THAN THEIR 3 HOURLY VALUES AND I BLENDED GUIDANCE
WITH CURRENT FORECAST AND THEN BUMPED UP VALUES A DEGREE OR TWO
ACROSS THE BOARD. A 3 DEGREE DEPARTURE FROM STATED 3 HOURLY
TEMPERATURES IS TOO MUCH...ESPECIALLY GIVEN THAT THE 0Z TO 12Z
TIME ONLY HAD A 2 OR 3 DEGREE TEMPERATURE DIFFERENCE FOR ANY SITE
FOR BOTH THE MAV AND MET GUIDANCE.
THIS WARMER START PLAYS INTO THE FORECAST AS THE RAIN WILL BE
OVERSPREADING THE AREA AND COULD BEGIN AS FREEZING RAIN FOR
PRIMARILY COLDER DRAINAGE AREAS. A WARM CORE OF AIR WILL BE FOUND
OVER SOUTHEASTERN CWA AND NOSE INTO THE I-71 CORRIDOR EARLY
WEDNESDAY. SNOW ALONG THE I-71 CORRIDOR MAY MIX WITH RAIN AT TIMES
AND THIS COULD CUT DOWN SIGNIFICANT SNOWFALL TOTALS HERE. A LOT OF
THIS REMAINS TO BE SEEN AND THAT IS WHY THE WATCH OVER
BUTLER/WARREN COUNTIES WAS CONTINUED AND THE OLD WATCH UPGRADED TO
A WARNING WHERE 6" OR BETTER OF SNOWFALL IS EXPECTED. WITH THE
UNCERTAINTY OF THESE TOTALS MIXING WITH RAIN AND THE POTENTIAL OF
FREEZING RAIN HERE...A TIER OF COUNTIES IN OHIO AND A NUMBER OF
COUNTIES OVER INDIANA HAVE BEEN ADDED. IN KY...IT ONLY INCLUDES
THOSE IN THE I-71 CORRIDOR.
THE SYSTEM IS FAIRLY PROGRESSIVE AND ANY RAIN SHOULD BE CHANGING
TO SNOW BY SUNSET WEDNESDAY. THIS TIME WILL ALSO MARK THE END OF
ANY LINGERING HEAVY SNOWFALL AND A TRANSITION TO LIGHT SNOW AND
FLURRIES. THIS LIGHT SNOW WILL LIKELY TURN OFF DURING THE
OVERNIGHT HOURS AS THE UPPER LEVEL DYNAMICS MOVE EAST AND RIDGING
BUILDS IN. THE DOWNWARD MOTION FROM ALOFT WILL NOT PERMIT
LINGERING FLURRIES TO PERSIST MUCH PAST MIDNIGHT OR SO.
COOLER TEMPERATURES WILL PREVAIL BEYOND WEDNESDAY AS NORTH WINDS
PULL COLD AIR TO THE REGION. CLOUD COVER WILL NOT PERMIT RUNAWAY
RADIATIONAL COOLING TO BE A FACTOR THROUGH THIS TIME.
HOWEVER...BEYOND THIS...ANY CLEARING AT NIGHT WILL COMBINE WITH
FRESH SNOW COVER TO LET TEMPERATURES DROP SIGNIFICANTLY.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
DEPARTING WINTER STORM WILL LEAVE DRY CONDITIONS AND SEASONABLE
TEMPERATURES AS SHORTWAVE RIDGING BUILDS IN OVER THE OHIO
VALLEY...DOWNSTREAM INTERMOUNTAIN WEST SHORTWAVE RIDGING. THIS
ENERGY ROTATING THROUGH A VERY BROAD LONGWAVE TROUGH CENTERED OVER
THE CONUS WILL LARGELY EJECT NORTH OF THE AREA INTO SATURDAY.
HOWEVER... THE BASE OF THE TROUGH WILL INTERACT WITH A DEEP MOISTURE
POOL OVER THE WESTERN GULF AND SEND AN ENHANCED STREAM OF MOISTURE
INTO THE OHIO VALLEY...WITH WEAK SFC LOW DEVELOPMENT OVER THE
SOUTHEAST.
HAVE KEPT MUCH OF THURSDAY /RESIDUAL SNOW SHOWER CHANCE MAINLY
EARLY/ DRY AND INTO FRIDAY AS WELL...AND THEN SPREAD SNOW CHANCES
BACK IN FRIDAY NIGHT AND THROUGH THE DAY SATURDAY. TEMP PROFILES
SUGGEST MAJORITY OF THIS HAS A BETTER SNOW CHANCE THAN RAIN
CHANCE...BUT ENSEMBLE PERSPECTIVE SUGGESTS THERE IS ENOUGH CHANCE AT
THIS TIME RANGE TO BRING A THREAT OF EITHER RAIN OR SNOW INTO PARTS
OF THE AREA ON SATURDAY...THOUGH RIGHT NOW IT APPEARS A BETTER SNOW
THREAT...WITH LIGHT ACCUMULATIONS...AND HAVE SET UP GRIDDED FORECAST
THAT WAY FOR NOW.
SYSTEM SHOULD BE TRANSIENT THUS DIMINISHING THREATS OF SNOW ON
SUNDAY AS TEMPERATURES REMAIN NEAR/SLIGHTLY BELOW NORMAL.
&&
.AVIATION /09Z TUESDAY THROUGH SATURDAY/...
NLY FLOW ON THE BACKSIDE OF LOW PRESSURE IS KEEPING IFR/MVFR ST
ACROSS THE TAFS. AS THE LOW CONTINUES TO MOVE E...WEAK HIGH
PRESSURE RIDGE WILL SLOWLY BUILD INTO THE REGION. MODELS DIFFER IN
THEIR HANDLING OF THE LOW LEVEL MOISTURE AND HOW MUCH IT CLEARS.
THE RAP MODEL KEEPS THE LOW LEVEL TRAPPED ACROSS THE REGION THE
ENTIRE DAY. THE NAM SCOURS IT OUT AROUND 12Z. THE GFS IS KIND OF
THE COMPROMISE AND KEEPS SOME MOISTURE ACROSS THE TAFS BUT LIFTS
AND BREAKS ITS UP A LITTLE. THIS LAST SOLUTION SEEMS THE MOST
REASONABLE...SO ALLOWED THE CIGS TO RISE TO AROUND 2500 FT AND GO
BROKEN. CIGS SHOULD RISE TO VFR AS THE LOW LOW LEVEL MOISTURE
WAINS.
THE EFFECTS OF THE MAJOR WINTER STORM START TO AFFECT CVG IN THE
EXTENDED PORTION OF THE 30 HR TAF. BROUGHT THE PCPN IN AS S THERE
AND DROPPED CIGS DOWN TO IFR AFT 06Z.
OUTLOOK...IFR CEILINGS AND VISIBILITIES OVERSPREADING THE REGION
TUESDAY NIGHT...CONTINUING WEDNESDAY INTO WEDNESDAY NIGHT.
CONDITIONS WILL LIFT TO MVFR ON THURSDAY. MVFR/IFR CEILINGS AND
VISIBILITIES POSSIBLE SATURDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...WINTER STORM WARNING FROM 1 AM WEDNESDAY TO 1 AM EST THURSDAY
FOR OHZ026-034-035-042>046-051>056-060>062.
WINTER STORM WATCH FROM LATE TONIGHT THROUGH LATE WEDNESDAY
NIGHT FOR OHZ063>065-070>072-077.
KY...WINTER STORM WATCH FROM LATE TONIGHT THROUGH LATE WEDNESDAY
NIGHT FOR KYZ089>091.
IN...WINTER STORM WARNING FROM 1 AM WEDNESDAY TO 1 AM EST THURSDAY
FOR INZ050-058-059-066.
WINTER STORM WATCH FROM LATE TONIGHT THROUGH LATE WEDNESDAY
NIGHT FOR INZ073>075-080.
&&
$$
SYNOPSIS...FRANKS
NEAR TERM...
SHORT TERM...FRANKS
LONG TERM...BINAU
AVIATION...SITES
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
110 AM EST TUE DEC 25 2012
.SYNOPSIS...
MOSTLY CLOUDY WEATHER IS EXPECTED TONIGHT AS WEAK LOW PRESSURE
MOVES EAST. AFTER A DRY CHRISTMAS DAY DUE TO WEAK HIGH
PRESSURE...A MAJOR WINTER STORM TRACKING FROM THE LOWER
MISSISSIPPI VALLEY TO THE CENTRAL APPALACHIANS WILL IMPACT THE
REGION CHRISTMAS NIGHT THROUGH WEDNESDAY NIGHT. A RIDGE OF HIGH
PRESSURE SHOULD BRING DRY CONDITIONS FOR THURSDAY AND FRIDAY.
ANOTHER LOW WILL PROVIDE MORE WINTRY PRECIPITATION ON SATURDAY.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
LATEST RUN OF THE FORECAST HAD ME INTRODUCE DRIZZLE AND FREEZING
DRIZZLE FOR OUR NORTHWEST 1/4 TO 1/3 OF CWA THROUGH DAYBREAK.
TEMPERATURES RIGHT AT THAT MAGICAL 32 OR ZERO DEPENDING ON YOUR
INCLINATION ARE PRETTY UNIFORM OVER MUCH OF THE REGION AT THIS
MOMENT IN TIME. NORTHWEST WINDS WILL TURN NORTH IN FAIRLY SHORT
ORDER AND HELP CEASE ANY FURTHER EASTWARD PROGRESSION TO ANY
DRIZZLE EARLY THIS MORNING.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH WEDNESDAY NIGHT/...
WEAK RIDGE BETWEEN LOWS WILL KEEP CONDITIONS DRY ON CHRISTMAS DAY.
PARTIAL SUNSHINE WILL ALLOW TEMPERATURES TO RISE CLOSE TO
NORMAL...IN THE UPPER 30S AND LOW 40S.
WEATHER WILL DETERIORATE RAPIDLY TUESDAY NIGHT AS LOW PRESSURE
SPINS UP AND MOVES TO TENNESSEE. THIS LOW WILL LIFT GULF MOISTURE
OVER A COLD AIRMASS IN LOWER LEVELS TO PRODUCE HEAVY WINTRY
PRECIPITATION. WENT CLOSER TO THE ECMWF SOLUTION WHICH HAS BEEN
QUITE CONSISTENT FOR SEVERAL DAYS IN BRINGING TEMPERATURE PROFILES
CONDUCIVE FOR WINTER PRECIP ACROSS MUCH OF THE ILN AREA. BASED ON
THAT LATEST GUIDANCE...HAVE EXPANDED OUR WINTER STORM WATCH
FARTHER SOUTH TO INCLUDE COLUMBUS AND DAYTON. EXPECT HEAVY SNOW OF
AROUND 6 INCHES THE WATCH AREA...WITH PERHAPS 1 TO 3 INCHES AT
LOCATIONS SOUTH OF THE WATCH AREA INCLUDING CINCINNATI...WHERE
WARMER AIR IS FORECAST TO FILTER IN AND ALLOW RAIN TO MIX IN ON
WEDNESDAY. SLEET ALSO MAY MIX IN FOR A TIME ON WEDNESDAY WHEN
MODEL SOUNDINGS INDICATE PARTIAL MELTING AND REFREEZING OF
HYDROMETEORS.
A LARGE PART OF THE IMPACT FROM THIS SYSTEM WILL INVOLVE WINDS
ASSOCIATED WITH THE TIGHT PRESSURE GRADIENT EVIDENT ON THE
NORTHWEST QUADRANT THE LOW CENTER. IN THE WATCH AREA...WINDS FROM
THE NORTHEAST ARE FORECAST TO BE AROUND 20 MPH SUSTAINED WITH
GUSTS AROUND 30 MPH. THOSE WINDS COMBINING WITH A BAND OF MODERATE
SNOW WILL PRODUCE CONSIDERABLE BLOWING AND DRIFTING...WHICH WILL
CAUSE OCCASIONAL WHITEOUTS THAT WILL MAKE POST-CHRISTMAS TRAVEL
ALL THE MORE DIFFICULT.
SNOW WILL TAPER OFF FROM WEST TO EAST ON WEDNESDAY NIGHT AS THE
LOW DEPARTS TO THE EAST COAST.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
DEPARTING WINTER STORM WILL LEAVE DRY CONDITIONS AND SEASONABLE
TEMPERATURES AS SHORTWAVE RIDGING BUILDS IN OVER THE OHIO
VALLEY...DOWNSTREAM INTERMOUNTAIN WEST SHORTWAVE RIDGING. THIS
ENERGY ROTATING THROUGH A VERY BROAD LONGWAVE TROUGH CENTERED OVER
THE CONUS WILL LARGELY EJECT NORTH OF THE AREA INTO SATURDAY.
HOWEVER... THE BASE OF THE TROUGH WILL INTERACT WITH A DEEP MOISTURE
POOL OVER THE WESTERN GULF AND SEND AN ENHANCED STREAM OF MOISTURE
INTO THE OHIO VALLEY...WITH WEAK SFC LOW DEVELOPMENT OVER THE
SOUTHEAST.
HAVE KEPT MUCH OF THURSDAY /RESIDUAL SNOW SHOWER CHANCE MAINLY
EARLY/ DRY AND INTO FRIDAY AS WELL...AND THEN SPREAD SNOW CHANCES
BACK IN FRIDAY NIGHT AND THROUGH THE DAY SATURDAY. TEMP PROFILES
SUGGEST MAJORITY OF THIS HAS A BETTER SNOW CHANCE THAN RAIN
CHANCE...BUT ENSEMBLE PERSPECTIVE SUGGESTS THERE IS ENOUGH CHANCE AT
THIS TIME RANGE TO BRING A THREAT OF EITHER RAIN OR SNOW INTO PARTS
OF THE AREA ON SATURDAY...THOUGH RIGHT NOW IT APPEARS A BETTER SNOW
THREAT...WITH LIGHT ACCUMULATIONS...AND HAVE SET UP GRIDDED FORECAST
THAT WAY FOR NOW.
SYSTEM SHOULD BE TRANSIENT THUS DIMINISHING THREATS OF SNOW ON
SUNDAY AS TEMPERATURES REMAIN NEAR/SLIGHTLY BELOW NORMAL.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
NLY FLOW ON THE BACKSIDE OF LOW PRESSURE IS KEEPING IFR/MVFR ST
ACROSS THE TAFS. AS THE LOW CONTINUES TO MOVE E...WEAK HIGH
PRESSURE RIDGE WILL SLOWLY BUILD INTO THE REGION. MODELS DIFFER IN
THEIR HANDLING OF THE LOW LEVEL MOISTURE AND HOW MUCH IT CLEARS.
THE RAP MODEL KEEPS THE LOW LEVEL TRAPPED ACROSS THE REGION THE
ENTIRE DAY. THE NAM SCOURS IT OUT AROUND 12Z. THE GFS IS KIND OF
THE COMPROMISE AND KEEPS SOME MOISTURE ACROSS THE TAFS BUT LIFTS
AND BREAKS ITS UP A LITTLE. THIS LAST SOLUTION SEEMS THE MOST
REASONABLE...SO ALLOWED THE CIGS TO RISE TO AROUND 2500 FT AND GO
BROKEN. CIGS SHOULD RISE TO VFR AS THE LOW LOW LEVEL MOISTURE
WAINS.
THE EFFECTS OF THE MAJOR WINTER STORM START TO AFFECT CVG IN THE
EXTENDED PORTION OF THE 30 HR TAF. BROUGHT THE PCPN IN AS S THERE
AND DROPPED CIGS DOWN TO IFR AFT 06Z.
OUTLOOK...IFR CEILINGS AND VISIBILITIES OVERSPREADING THE REGION
TUESDAY NIGHT...CONTINUING WEDNESDAY INTO WEDNESDAY NIGHT.
CONDITIONS WILL LIFT TO MVFR ON THURSDAY. MVFR/IFR CEILINGS AND
VISIBILITIES POSSIBLE SATURDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...WINTER STORM WATCH FROM LATE TONIGHT THROUGH LATE WEDNESDAY
NIGHT FOR OHZ026-034-035-042>046-051>056-060>062-070-071.
KY...NONE.
IN...WINTER STORM WATCH FROM LATE TONIGHT THROUGH LATE WEDNESDAY
NIGHT FOR INZ050-058-059-066.
&&
$$
SYNOPSIS...CONIGLIO
NEAR TERM...FRANKS/HICKMAN
SHORT TERM...CONIGLIO
LONG TERM...BINAU
AVIATION...SITES
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
804 PM MST WED DEC 26 2012
.UPDATE...MINOR UPDATES WERE MADE TO INCREASE POPS OVER PARTS OF
NORTHEAST WYOMING AND NORTHWEST SOUTH DAKOTA WHERE PERSISTENT SNOW
BANDS HAVE DEVELOPED THIS EVENING. HRRR GUIDANCE INDICATES THESE
FEATURES WILL CONTINUE INTO THE OVERNIGHT HOURS.
&&
.PREV DISCUSSION... /ISSUED 430 PM MST WED DEC 26 2012/
AVIATION...00Z TAF UPDATE
CONDITIONS ARE EXPECTED TO DETERIORATE ACROSS NORTHEAST WYOMING
AND WESTERN SOUTH DAKOTA DURING THE NEXT SEVERAL HOURS AS AN UPPER
LOW CROSSES THE NORTHERN ROCKIES AND REDEVELOPS OVER NORTHEAST
WYOMING...PRODUCING A BROAD AREA OF LIGHT SNOW. WIDESPREAD IFR
WITH LOCAL LIFR CIGS AND VSBYS ARE FORECAST TO DEVELOP BY AROUND
02Z IN NORTHEAST WYOMING AND SPREAD EASTWARD. LITTLE OR NO
IMPROVEMENT IS EXPECTED THROUGH MOST OF THE DAY THURSDAY AS THE
WRAP AROUND CONVEYOR OF MOIST AIR MOVES LEISURELY ACROSS THE
DAKOTAS.
PREV DISCUSSION... /ISSUED 258 PM MST WED DEC 26 2012/
DISCUSSION...UPPER LEVEL ANALYSIS HAS WEAK RIDGE OVER THE SOUTH
CENTRAL PLAINS WITH LARGE TROF ACROSS THE WESTERN CONUS.
DEVELOPING SHORTWAVE OVER NORTHERN UTAH/SW WYOMING IS LIFTING OUT
OF THE TROF AT THE MOMENT. CLOUD COVER IS ON THE INCREASE ACROSS
THE FORECAST AREA. AT THE SURFACE...ARCTIC HIGH PRESSURE STILL
DOMINATES THE NORTHERN PLAINS. WEAK SURFACE LOW PRESSURE IS
STRENGTHENING ACROSS SOUTH CENTRAL WYOMING...WITH AN INVERTED TROF
EXTENDING INTO NORTHEAST WYOMING. TEMPERATURES ARE MAINLY IN THE
TEENS TO LOWER 20S ACROSS THE AREA...WITH LIGHT SOUTH TO SOUTHEAST
WINDS.
FOR TONIGHT...UPPER TROUGH WILL DIG INTO THE FOUR CORNERS AS WEAK
SHORTWAVE EJECTS INTO THE NORTHERN PLAINS. BEST DYNAMICS WILL SKIRT
JUST TO THE SOUTH OF THE FORECAST AREA...BUT WEAK ENERGY AND FORCING
ASSOCIATED WITH MAIN TROF WILL BRING ANOTHER ROUND OF SNOW TO THE
AREA. SNOW WILL BEGIN THIS EVENING ACROSS NORTHEAST WYOMING AND
FAR WESTERN SOUTH DAKOTA...AND SPREAD EASTWARD LATER TONIGHT. SNOW
ACCUMULATIONS OF AROUND AN INCH WILL BE POSSIBLE ACROSS WESTERN
AREAS OVERNIGHT. TEMPERATURES WILL FALL INTO THE SINGLE DIGITS FOR
MOST LOCATIONS.
ON THURSDAY...UPPER TROF CROSSES THE AREA AS MID LEVEL CLOSED LOW
SLIDES THROUGH NEBRASKA. SURFACE LOW REMAINS WELL SOUTH OF THE
AREA AS ARCTIC HIGH DOMINATES. INVERTED SURFACE TROF SLIDES ACROSS
THE DAKOTAS...SWITCHING WINDS FROM EAST SOUTHEAST TO THE NORTH.
BEST ENERGY/SNOWFALL WILL REMAIN OVER NORTHEAST WYOMING...THE
NORTHERN BLACK HILLS...AND NORTHWEST SOUTH DAKOTA WITH THIS SYSTEM.
LATER IN THE DAY...CLOSED MID LEVEL LOW OVER NEBRASKA WILL
ORGANIZE...AND PRODUCE A MODERATE BAND OF SNOW OVER SOUTH CENTRAL
SOUTH DAKOTA THROUGH THURSDAY NIGHT. SNOWFALL TOTALS SHOULD BE
AROUND 2 TO 3 INCHES FROM NORTHEAST WYOMING...THE NORTHERN
HILLS...INTO NORTHWEST SOUTH DAKOTA BY THURSDAY EVENING. SOUTH
CENTRAL SOUTH DAKOTA SHOULD ALSO SEE ABOUT 2 TO 3 INCHES. IN
BETWEEN...1 TO 2 INCHES WILL BE POSSIBLE. WITH ABUNDANT CLOUDS AND
SNOW...HIGH TEMPERATURES WILL STRUGGLE INTO THE TEENS.
FOR FRIDAY...UPPER LEVEL CYCLONIC FLOW WILL CONTINUE THROUGH
FRIDAY...HOWEVER NO PRECIPITATION IS EXPECTED. PLENTY OF
CLOUDINESS IS EXPECTED FRIDAY MORNING...BUT WITH DRIER AIR MOVING
IN FROM THE WEST...NORTHEAST WYOMING AND SOUTHWESTERN SOUTH DAKOTA
MAY SEE SOME SUNSHINE BEFORE THE END OF THE DAY. HIGHS WILL BE IN
THE UPPER TEENS TO MID 20S.
EXTENDED...LONG WAVE TROF OVER THE GREAT LAKES AND UPPER RIDGE OVER
NORTHERN PLAINS WILL GIVE THE FORECAST AREA WARMER TEMPERATURES FOR
THE WEEKEND...WITH HIGHS NEAR NORMAL. AS RIDGE SHIFTS TO THE
EAST...NEXT TROF DEEPENS ACROSS THE WESTERN US...WITH CUT-OFF LOW
OVER THE SOUTHWESTERN US AND NORTHWEST FLOW OVER NORTHERN PLAINS
THROUGH MIDWEEK. DIFFERENCES IN MODEL TIMING OF SEVERAL SHORT WAVES
RESULTS IN LOW POPS...BUT WOULD EXPECT OCCASIONAL CHANCES OF PRECIP
TO INCREASE IN THE SHORT TERM. ARCTIC AIR PROGGED TO REMAIN NORTH
AND EAST OF THE FORECAST AREA...SO WILL MAINTAIN GRADUAL WARMING
TREND.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&
$$
SHORT TERM...CARPENTER
LONG TERM....WFO UNR
AVIATION...CARPENTER
AREA FORECAST DISCUSSION
NWS MEMPHIS TN
513 PM CST WED DEC 26 2012
.DISCUSSION... /ISSUED 346 PM CST WED DEC 26 2012/
SEVERAL FORECAST CHALLENGES OVER THE NEXT WEEK. WITH THE LATE
CHRISTMAS NIGHT SHOW STORM WELL OFF TO THE EAST...LOW CLOUDS
LINGERED EAST OF THE MS RIVER. NOCTURNAL POST FRONTAL COOL SEASON
STRATUS OFTEN IS MORE PERSISTENT THAN THE MODELS SUGGEST...AND
HAVE DELAYED THE CLEARING BY A FAIR AMOUNT TONIGHT. SKIES WILL
MORE LIKELY REMAIN CLEAR WHERE HEAVY SNOW OCCURRED LAST NIGHT...
LEADING TO PRIME RADIATIONAL COOLING CONDITIONS AND AN OUTSIDE
CHANCE OF FREEZING FOG TOWARD SUNRISE.
THURSDAY WILL SEE MODIFIED ARCTIC SURFACE HIGH PRESSURE OVER THE
MIDSOUTH...UNDER FAST SOUTH/SOUTHWEST FLOW FLOW ALOFT. THE MODELS
ARE CONSISTENT IN BRINGING A LOW AMPLITUDE SOUTHERN BRANCH
SHORTWAVE INTO THE ARKLAMISS REGION FRIDAY EVENING. ELEVATED
SHOWERS WILL DEVELOP IN THE WARM ADVECTION AND ISENTROPIC LIFT
REGION IN ADVANCE OF THE SHORTWAVE EARLY FRIDAY. NAM SOUNDINGS
POINT TO ALL LIQUID PRECIP ACROSS THE MIDSOUTH FRIDAY MORNING...
BUT SUSPECT THE NAM BOUNDARY LAYER TEMPS MAY BE TOO WARM GIVEN THE
RESIDUAL SNOWPACK. THERE IS THUS AN OUTSIDE CHANCE OF LIGHT
FREEZING RAIN NORTH OF I40 AND MAINLY WEST OF THE MS RIVER FRIDAY
MORNING...BEFORE CHANGING TO RAIN TOWARD MIDDAY FRIDAY.
FOLLOWING ANOTHER COLD FRONTAL PASSAGE SATURDAY... SUNDAY SHOULD
SEE LOW AMPLITUDE RIDGING ALOFT AND FAIR WEATHER ACROSS THE MIDSOUTH.
12Z GFS AND ECMWF MODELS CONTINUE TO SHOW SIGNIFICANT DISAGREEMENT
BEYOND MONDAY... MAKING THE EXTENDED FORECAST PERIODS A CHALLENGE.
OF THE ECMWF...GFS AND CMC MODELS...THE ECMWF APPEARS TO BE A
APPROXIMATE COMPROMISE BETWEEN THE PROGRESSIVE GFS AND THE MUCH
SLOWER CMC MODEL. WITH THE ECMWF ALSO EXHIBITING BETTER RUN TO
RUN CONSISTENCY... HAVE BASED THE MONDAY THROUGH WEDNESDAY PERIODS
ALMOST ENTIRELY ON THE ECMWF. THIS WOULD SUGGEST ANY SIGNIFICANT
PRECIPITATION WOULD HOLD OFF UNTIL MID TO LATE NEXT WEEK..UNTIL A
GREAT BASIN REX BLOCK FINALLY BREAKS DOWN...SENDING SOUTHERN
BRANCH UPPER LEVEL ENERGY TOWARD THE LOWER MS RIVER VALLEY.
PWB
&&
.AVIATION...
00Z TAF SET
LOW CLOUDS SEEM TO BE HOLDING TIGHT ACROSS THE MIDSOUTH. CLEARING
LINE HAS MOVED LITTLE OVER THE LAST HOUR. LATEST RUC CLEARS OUT
KMEM FOR A COUPLE OF HOURS BEFORE BRINGING MVFR CIGS BACK IN.
BEGINNING TO WONDER IF KMEM WILL CLEAR AT ALL. WILL MAKE LAST
MINUTE ADJUSTMENT TO TAF BASED ON SATELLITE BUT RIGHT NOW LEANING
TOWARD GOING SCT AT 2000 FT AND THEN INTRODUCING A TEMPO GROUP
BETWEEN 5 AND 9Z FOR BKN MVFR CIGS. KMKL AND KTUP WILL STAY SOCKED
IN THROUGH AT LEAST 12-17Z. KJBR IS CLEAR NOW BUT EITHER FOG...LOW
CLOUDS OR MAYBE BOTH WILL BRING CONDITIONS BACK TO MVFR AFTER 6Z.
WINDS CONTINUE TO DIE DOWN. EXPECT LIGHT WINDS OVER THE NEXT 24
HOURS DUE TO THE HIGH BUILDING INTO THE AREA.
KRM
&&
&&
.PRELIMINARY POINT TEMPS/POPS...
MEM 24 39 32 43 / 0 0 10 70
MKL 20 37 27 44 / 10 0 10 60
JBR 15 33 25 36 / 0 0 10 50
TUP 24 45 31 52 / 0 0 10 90
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
MO...NONE.
MS...NONE.
TN...NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS SAN ANGELO TX
334 AM CST TUE DEC 25 2012
.SHORT TERM...
THE COMBINATION OF STRONG WINDS AND SNOW WILL REDUCE VISIBILITIES
AND MAKE TRAVEL DIFFICULT ACROSS THE NORTHERN BIG COUNTRY AFTER 9
AM. STRONG WINDS AND FREEZING TEMPERATURES WILL ALSO RESULT IN WIND
CHILL VALUES LOWERING INTO THE SINGLE DIGITS BY EARLY EVENING.
WINTER WEATHER ADVISORY IS IN EFFECT FOR THROCKMORTON TODAY FOR 1-3
INCHES OF SNOW...WINTER WEATHER ADVISORY WILL BE ISSUED SHORTLY FOR
HASKELL...JONES...AND SHACKELFORD COUNTIES FOR 1 TO 2 INCHES OF
SNOW. A WIND ADVISORY IS ALSO IN EFFECT FOR STRONG NORTH WINDS.
LATEST RUC MODEL IS SHOWING THE BEST SNOWFALL ACCUMULATIONS ACROSS
THROCKMORTON COUNTY...AND THIS COUNTY WILL BE HAVE TO BE WATCHED
CLOSELY FOR A POSSIBLE UPGRADE TO WINTER STORM WARNING IF SNOWFALL
TOTALS ARE EXPECTED TO EXCEED 4 INCHES.
AS THE UPPER LEVEL LOW DIGS A LITTLE FURTHER SOUTH...IT SHOULD TRACK
SOUTHEAST ACROSS THE NORTHERN BIG COUNTRY TODAY. THE BEST CHANCE
FOR SNOW WILL BE FROM 9AM THROUGH 6PM WHEN TEMPERATURES ARE EXPECTED
TO PLUNGE BELOW FREEZING AND SOUNDINGS PROG THE BEST SNOW
POTENTIAL. THE NORTHERN BIG COUNTRY...MAINLY FROM ROTAN TO ALBANY
AND NORTH IS THE AREA THAT HAS THE BEST CHANCE OF RECEIVING SNOW
TODAY SINCE THIS REGION IS LOCATED TO THE NORTHWEST OF THE SURFACE
LOW THAT WILL TRACK FROM FAR WEST TEXAS...TO CENTRAL TEXAS AND THEN
INTO SOUTHEAST TEXAS TODAY.
COULD SEE LIGHT SNOWFALL ACCUMULATIONS FROM A DUSTING TO LESS THAN
AN INCH ALONG THE I20 CORRIDOR COMMUNITIES OF SWEETWATER...ABILENE
AND BAIRD. A FEW SHOWERS ARE POSSIBLE THIS MORNING ACROSS MOST OF
THE AREA IN THE WARM AIR ADVECTION IN ADVANCE OF THE UPPER LOW. A
FEW THUNDERSTORMS ARE ALSO POSSIBLE ACROSS THE EASTERN COUNTIES.
THE SNOW SHOULD END BY 6PM AS THE UPPER LOW PRESSURE SYSTEM
DEPARTS. AS SKIES CLEAR TONIGHT...LOW TEMPERATURES WILL DROP OFF
QUICKLY ESPECIALLY ACROSS THE SNOW COVERED FIELDS OF THE NORTHERN
BIG COUNTRY.
26
.LONG TERM...
UPPER RIDGE WILL BUILD OVER THE FORECAST AREA IN THE WAKE OF THE
DEPARTING UPPER LOW...THEN QUICKLY BACK TO THE SOUTHWEST BY THURSDAY
IN RESPONSE TO A DEVELOPING UPPER LOW OVER THE SOUTHWEST. COLD
POSTFRONTAL HIGHS ON WEDNESDAY WILL ONLY BE IN THE LOW TO MID 30S
OVER THE BIG COUNTRY WITH UPPER 30S TO MID 40S SOUTH OF INTERSTATE
20. AFTER ANOTHER COLD MORNING ON THURSDAY WITH LOWS IN THE MID
TEENS TO THE LOWER 20S...WILL SEE AFTERNOON HIGHS ON THURSDAY IN THE
LOWER TO UPPER 50S.
BOTH ECMWF AND GFS MOVE THE NEXT UPPER LOW OVER THE CENTRAL PLAINS
BY LATE THURSDAY...PUSHING THE NEXT COLD FRONT THROUGH THE FORECAST
AREA DURING THE DAY ON FRIDAY. A SERIES OF FRONTAL PASSAGES INTO THE
BEGINNING OF THE COMING WEEK WILL KEEP AFTERNOON HIGHS AT OR BELOW
SEASONAL NORMS.
AS WE APPROACH THE NEW YEAR...THINGS GET A LITTLE COMPLICATED. THE
GFS ENSEMBLE IS CHAOTIC WITH THE PREFERRED SOLUTION ELUDING TO A
CLOSED LOW OVER THE BAJA MONDAY THROUGH MID-WEEK. THIS SCENARIO
INTRODUCES RAINFALL OVER THE FORECAST AREA EARLY MONDAY AND KEEPS A
CHANCE OF RAINFALL THROUGH MID-WEEK AS A SOUTHWEST FLOW ALOFT
CONTINUES OVER THE AREA. THE ECMWF OPENS AN UPPER TROUGH OVER THE
BAJA EARLY MONDAY AND THEN CLOSES AN UPPER LOW OVER THE BAJA ON
TUESDAY...WITH THE BEST CHANCE OF RAINFALL OVER OUR AREA LATE
TUESDAY. WILL GO WITH THE GFS WHICH INTRODUCES MOISTURE OVER THE CWA
DURING THE DAY ON MONDAY. WILL KEEP MOISTURE OVER THE AREA THROUGH
THE END OF THE EXTENDED AS BOTH MODELS SHOW PRECIP ON TUESDAY. WITH
KEEP PRECIP TYPE LIGHT RAIN AT THIS TIME BUT AS WILL GET FURTHER
DOWN THE ROAD...THERE MAY BE A CHANCE FOR FROZEN PRECIP ENCROACHING
ON NORTHWESTERN COUNTIES LATER INTO THE WEEK.
15
&&
.PRELIMINARY POINT TEMPS/POPS...
ABILENE 39 15 31 22 53 / 40 5 0 0 0
SAN ANGELO 48 18 41 23 58 / 30 0 0 0 0
JUNCTION 58 22 45 19 59 / 20 0 0 0 0
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY FROM 10 AM THIS MORNING TO 8 PM CST THIS EVENING
FOR THE FOLLOWING ZONES: BROWN...CALLAHAN...COKE...COLEMAN...
CONCHO...CROCKETT...FISHER...HASKELL...IRION...JONES...KIMBLE...
MASON...MCCULLOCH...MENARD...NOLAN...RUNNELS...SAN SABA...
SCHLEICHER...SHACKELFORD...STERLING...SUTTON...TAYLOR...
THROCKMORTON...TOM GREEN.
WINTER WEATHER ADVISORY FROM 10 AM THIS MORNING TO 6 PM CST THIS
EVENING FOR THE FOLLOWING ZONES:
HASKELL...JONES...SHACKELFORD...THROCKMORTON.
&&
$$
15
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1150 PM CST MON DEC 24 2012
.AVIATION...
/06Z TAFS/
CONCERNS...THREAT FOR THUNDER OVERNIGHT AND EARLY TUESDAY
MORNING. CHANGE OVER TO SNOW IN THE DFW METROPLEX TUESDAY
AFTERNOON. STRONG AND GUSTY NORTHWEST WINDS TUESDAY AFTERNOON
THROUGH THE OVERNIGHT HOURS.
WIDESPREAD LIGHT SHOWERS ARE ALREADY DEVELOPING ACROSS THE REGION
AND MVFR STRATUS IS SPREADING NORTH INTO WACO. THE METROPLEX TAF
SITES WILL REMAIN VFR UNTIL THE PRECIPITATION INCREASES BY 08-09Z
BUT WACO WILL CONTINUE IN MVFR THROUGH THE NIGHT. EXPECT SHOWERS
AND SCATTERED THUNDERSTORMS TO OCCUR THROUGH THE OVERNIGHT HOURS
WITH REDUCED VISIBILITIES AND MVFR CIGS. THE POTENTIAL FOR THUNDER
IS HIGHER AT WACO AND SOME SEVERE STORMS ARE POSSIBLE AROUND THE
WACO AREA AS WELL...WITH A THREAT FOR HAIL. LATEST GUIDANCES
SUGGEST THE SHOWER ACTIVITY COULD BECOME HEAVIER CLOSER TO
DAYBREAK AS AN UPPER LEVEL LOW GETS CLOSER TO THE REGION AND LIFT
INCREASES. THIS COULD RESULT IN TEMPORARY IFR CONDITIONS AT ALL
TAF SITES DURING PERIODS OF HEAVY SHOWERS AND/OR THUNDERSTORMS.
THE PRECIPITATION WILL CONTINUE FOR MOST OF THE DAY WITH A
CHANGE OVER TO SNOW IN THE DFW METROPLEX IN THE EARLY TO MID
AFTERNOON HOURS. THERE COULD ALSO BE A BRIEF WINDOW OF SLEET MIXED
IN AS WELL BEFORE THE CHANGE OVER TO ALL SNOW. THE SNOW WILL LAST
FOR A FEW HOURS AND ACCUMULATIONS UP TO AN INCH ARE POSSIBLE. AT
THIS SAME TIME...A STRONG FRONT WILL SWEEP ACROSS THE METROPLEX
RESULTING IN VERY STRONG NORTHWEST WINDS. THE WINDS COULD CAUSE
BLOWING SNOW THAT COULD REDUCE VISIBILITIES. CONDITIONS OVERALL
SHOULD INCREASE IN THE EVENING HOURS AS THE SYSTEM MOVES
EAST...BUT THE STRONG WINDS WILL CONTINUE OVERNIGHT.
AT KACT...THE PRECIPITATION IS EXPECTED TO REMAIN ALL LIQUID...
ENDING DURING THE AFTERNOON HOURS. THE FRONT WILL ARRIVE AROUND
MIDDAY. THERE IS A SMALL CHANCE FOR SOME FLURRIES BUT THE
POTENTIAL IS FAIRLY LOW.
CEILINGS SHOULD IMPROVE AT ALL SITES TUESDAY EVENING BUT THERE IS
A POTENTIAL THAT THE MVFR CIGS BEHIND THIS SYSTEM COULD HOLD IN
LONGER THAN IS IN THE CURRENT TAF FORECAST.
82/JLD
&&
.UPDATE...
WE HAVE ANALYZED THE 00Z UPPER AIR DATA AND HAVE WATCHED THE
SURFACE OBS CLOSELY FOR SIGNS OF ANY DISCREPANCIES BETWEEN THEM
AND THE MODEL DATA. THE BIG THING THAT STANDS OUT ARE THAT THE
SURFACE LOW IN NORTHEAST NEW MEXICO AT 6PM WAS ABOUT 80 MILES
FARTHER SOUTH THAN ALL OF THE MODELS HAD FORECAST 24 HOURS AGO.
WHEN DEALING WITH A SWINGING/DIGGING UPPER LEVEL SYSTEM...THE
SURFACE PRESSURE PATTERN AND PRESSURE TENDENCIES OFFER ENORMOUS
CLUES ON THE FUTURE TRACK OF A POTENTIAL VORTICITY ANOMALY BEFORE
IT CLOSES OFF TO BECOME A FULL FLEDGED UPPER LOW. THE 3PM AND 6PM
SURFACE ANALYSIS SHOWED A LARGE REGION OF PRESSURE FALLS ACROSS
NEW MEXICO AND WEST TEXAS IN ADVANCE OF THE SYSTEM. GIVEN THE
ORIENTATION OF THE PRESSURE FALLS AND LOCATION OF THE SURFACE
LOW...IT CAN BE DETERMINED WITHOUT EVEN LOOKING AT A FORECAST
MODEL THAT THE UPPER LOW HAS NOT FINISHED DIGGING SOUTH. THE BIG
QUESTION IS HOW FAR SOUTH WILL THE UPPER LOW MAKE IT BEFORE IT
BEGINS TO SWING BACK TO THE NORTHEAST. AT THIS HOUR PRESSURE FALLS
CONTINUE IN THE REGION FROM LUBBOCK TO MIDLAND...WITH ANOTHER
PRESSURE FALL AREA DEVELOPING IN SOUTHEAST TEXAS. EXTRAPOLATING
SUGGESTS THE UPPER LOW WILL TRACK JUST SOUTH OF LUBBOCK BY SUNRISE
AND TO NEAR WACO BY SUNSET. AS THE LOW APPROACHES WACO...A WARM
FRONT WILL BE ORGANIZING OUT OF THE WEAK STATIONARY FRONT
CURRENTLY ANALYZED FROM SAN ANTONIO TO HOUSTON. BAROCLINIC QG
THEORY SUGGESTS THAT ONCE LOW LEVEL WARM ADVECTION BEGINS IN
EARNEST ACROSS SOUTHEAST TEXAS BY MORNING...IT WILL INDUCE HEIGHT
RISES TO THE SOUTHEAST OF OUR UPPER LOW WHICH WILL CAUSE THE LOW
TO CLOSE OFF AND FINISH DIGGING SOUTH...AND START ITS GRADUAL
TURN TO THE NORTHEAST. TOMORROW EVENING I WOULD EXPECT THE LOW TO
TRACK FROM NEAR WACO TO NEAR SHREVEPORT. IN SUMMARY THE USUAL
MEDIUM RANGE MODELS APPEAR TO BE A LITTLE TOO FAR NORTH WITH THE
TRACK OF THE UPPER LOW. OUR EXPECTATIONS FOR THE TRACK OF THE LOW
ALIGN WELL WITH THE RAP FORECAST WHICH IS TO THE SOUTH OF ALL
OTHER MODELS...SO WE WILL USE THE RAP HEAVILY.
OUR FORECAST HAS BEEN ON THE SOUTHERLY SIDE AND SNOWIER SIDE OF
THE MODEL GUIDANCE. SO ALTHOUGH WE ARE SEEING AN EVEN MORE
SOUTHERLY TRACK COME TO FRUITION...THIS DOES NOT NECESSARILY
MEAN THE FORECAST SNOW AMOUNTS NEED TO BE AMENDED MUCH. THIS IS IN
PART DUE TO THE DIFFICULTY IN GETTING THE COLDER/SUBFREEZING AIR
FARTHER SOUTH BEFORE THE PRECIPITATION ENDS. THE EXCEPTION IS THE
NORTHWEST ZONES WHERE THE MORE SOUTHERLY TRACK SUGGESTS MORE
PRECIP WILL FALL IN SUBFREEZING AIR. DUE TO THE TERRAIN EFFECTS
HERE...COLD AIR HAS AN EASY TIME GETTING INTO OUR NORTHWEST ZONES
WHEN WE HAVE A NORTH/NORTHEAST SURFACE WIND. HAVE EXPANDED THE
SNOW ADVISORY TO INCLUDE YOUNG/JACK/WISE COUNTIES...AND HAVE
INCREASED SNOW TOTALS TO THE 2-4 INCH RANGE FROM BOWIE TO SHERMAN.
THE NORTHEAST ZONES LIKELY WONT SWITCH TO SNOW UNTIL LATE
AFTERNOON...AS COLD AIR WILL HAVE TROUBLE MOVING IN AT THE SURFACE
DUE TO THE LEE SHADOW WARMING EFFECT OF THE OZARK PLATEAU. MOST OF
THE SNOW THAT OCCURS THERE WILL BE AFTER 6 PM AND WILL BE HIGHLY
DEPENDENT ON WHETHER MESOSCALE BANDING CAN SET UP IN THE WAKE OF
THE UPPER LOW. THE NEW NAM HAS FINALLY FORECAST SOME SIGNIFICANT
BANDING TO OCCUR...THUS WILL LEAVE THE ADVISORY ALONE IN THIS
AREA...BUT CONFIDENCE IS A LITTLE LOWER IN THE NORTHEAST ZONES FOR
2+ INCHES OF SNOW.
FARTHER TO THE SOUTH OF THE ADVISORY...FOR THE I-20 CORRIDOR AND
INCLUDING THE METROPLEX...THERE IS NOW HIGH CONFIDENCE THAT SNOW
WILL OCCUR. HOWEVER ALL INDICATIONS ARE THAT IT WILL STILL BE A
BRIEF 1-3 HOUR EVENT WITH NOT ENOUGH TIME TO GET ACCUMULATIONS
OVER AN INCH. IT MUST BE STRESSED THAT WITH TEMPERATURES FALLING
INTO THE 20S BY SUNSET...ANY APPRECIABLE MOISTURE REMAINING ON
BRIDGES...OVERPASSES AND EVEN SURFACE STREETS WILL LIKELY RE-
FREEZE INTO BLACK ICE. ALTHOUGH WE ARE USING 1+ INCH AS CRITERIA
FOR THE COUNTIES IN THE WINTER WEATHER ADVISORY AREA...WE MAY
EXPAND THE ADVISORY SOUTH INTO THE METROPLEX OVERNIGHT DUE SOLELY
TO TRAVEL IMPACTS.
FINALLY CONCERNING THE SEVERE WEATHER THREAT. WITH A MORE SOUTHERLY
TRACK OF THE UPPER LOW...THIS MEANS THERE IS LESS OF A CHANCE OF THE
WARM FRONT MAKING IT INTO THE SOUTHEAST CWA TONIGHT AS IT WILL
LIKELY STAY SOUTHEAST OF THE AREA. ELEVATED THUNDERSTORMS ARE STILL
EXPECTED TO RAPIDLY INCREASE IN COVERAGE AFTER 3 AM...WITH ELEVATED
INSTABILITY HIGH ENOUGH FOR A FEW SEVERE HAIL STORMS SOUTH OF I-20.
HAVE TONED DOWN THE DAMAGING WIND AND TORNADO THREAT FROM OUR
PRODUCTS...BUT WE WILL CONTINUE TO ADVERTISE HAIL STORMS POSSIBLE
LATE TONIGHT AND EARLY TOMORROW MORNING.
TR.92
&&
.PREV DISCUSSION... /ISSUED 301 PM CST MON DEC 24 2012/
OUR CHRISTMAS DAY/NIGHT WINTER STORM IS TAKING SHAPE OVER THE
INTERIOR WEST THIS AFTERNOON. IT WILL MOVE SOUTHEAST OVERNIGHT AND
SHOULD DEVELOP A CLOSED CIRCULATION AS IT ENTERS THE SOUTHWESTERN
PANHANDLE BY DAYBREAK CHRISTMAS. ALTHOUGH TODAY/S MODEL SOLUTIONS
CONTINUE TO SHOW SLIGHT TIMING AND TRACKING DIFFERENCES...THE
AGREEMENT AND CONSENSUS BETWEEN THE GFS AND THE ECMWF HAVE BEEN
AND CONTINUE TO BE THE PREFERRED SOLUTION FOR THIS STORM. THE
500MB CENTER SHOULD TRACK ALONG I-20 BETWEEN ABILENE AND DFW THEN
JUST SOUTH OF I-30 FROM DFW TO TEXARKANA. IF THE TRACK IS 30 MILES
SOUTH OR NORTH OF OUR FORECAST THEN IMPACTS WILL ALSO SHIFT ACCORDINGLY.
LAST NIGHTS FRONT IS LOCATED FROM NORTH OF HOUSTON TO NEAR SAN ANTONIO
TO AROUND FORT STOCKTON. SURFACE CYCLOGENESIS WILL BEGIN OVERNIGHT
ALONG THIS FRONT AND TRACK EAST ALONG THE FRONT. WE ARE EXPECTING
A WARM FRONT TO LIFT THROUGH THE SOUTHERN AND SOUTHEAST COUNTIES
LATE TONIGHT AND THROUGH THE EAST-CENTRAL COUNTIES EARLY CHRISTMAS
MORNING AS THE SURFACE LOW SLIDES EAST. CONVECTION WILL BEGIN
OVERNIGHT AS THE ELEVATED WARM FRONT PUSHES NORTHWARD. STRONG
UPPER DYNAMICS AND MID LEVEL INSTABILITY WILL LEAD TO SOME STRONG
TO SEVERE THUNDERSTORMS BEFORE AND AFTER DAYBREAK. HAIL WILL BE
THE MAIN THREAT BUT DAMAGING WIND CAN BE EXPECTED ALONG AND SOUTH
OF THE SURFACE BOUNDARY. AS FOR TORNADOES...STORMS MOVING OVER THE
SURFACE BOUNDARY WILL EXPERIENCE AN INCREASE IN STORM-RELATIVE
HELICITY AND BRIEF TORNADOES ARE POSSIBLE. THE SEVERE WEATHER
THREAT SHOULD MOVE INTO EAST TEXAS BY LATE MORNING.
COLD ARCTIC AIR HAS BEEN BUILDING OVER THE NORTHERN AND CENTRAL
PLAINS AND WILL SURGE INTO NORTH TEXAS BEHIND THE EXITING
SURFACE LOW. THIS WILL RESULT IN RAIN TRANSITIONING TO SNOW WEST
TO EAST ALONG AND NORTH OF I-20 FROM LATE MORNING (NW) THROUGH
MID AFTERNOON (NE). WE STILL EXPECT 1-3 INCHES OVER THE NORTHERN
TWO ROWS OF COUNTIES WITH THE HIGHEST AMOUNTS GENERALLY EAST OF A
SHERMAN TO GREENVILLE LINE. WOULD NOT BE SURPRISED IF A BAND OF
HEAVIER SNOW OCCURRED OVER THE NORTHEAST COUNTIES AROUND PARIS
WHERE THE 700MB FRONTOGENESIS IS MORE LIKELY TO ENHANCE THE
WRAP-AROUND BANDING. THE SNOW IS EXPECTED TO END OVER THE
NORTHEAST BY MIDNIGHT. SNOW ACROSS OKLAHOMA AND WESTERN ARKANSAS
COULD TOTAL 4-8 INCHES...AND TRAVEL NORTH OF THE RED RIVER OR INTO
WESTERN ARKANSAS WILL BE TREACHEROUS CHRISTMAS DAY THROUGH
WEDNESDAY.
A WIND ADVISORY WILL BE NEEDED CHRISTMAS AFTERNOON AND NIGHT AS
NORTH WINDS BLOW 20-30 MPH WITH GUSTS TO 40MPH. BLOWING SNOW WILL
BE POSSIBLE IN THE AFTERNOON AND OVERNIGHT HOURS WHERE SNOW HAS
OCCURRED. IT WILL BE BITTERLY COLD ON CHRISTMAS NIGHT WITH WIND
CHILLS IN THE LOWER SINGLE DIGITS AND TEENS. ALSO ANY MOISTURE
REMAINING ON ROADWAYS CHRISTMAS EVENING WILL FREEZE OVERNIGHT SO
WEDNESDAY MORNING COMMUTERS NEED TO BE ALERT FOR ICY SPOTS.
COLD AND DRY FOR WEDNESDAY. TEMPERATURES MODERATE ON THURSDAY AS
WINDS RETURN SOUTH. ANOTHER COLD FRONT WILL MOVE THROUGH THE
REGION FRIDAY WITH A CHANCE OF SHOWERS OVER THE CENTRAL AND
EASTERN COUNTIES. TEMPERATURES BEHIND THIS FRONT WILL NOT BE AS
COLD...BUT WILL KEEP HIGHS/LOWS BELOW NORMAL OVER THE WEEKEND.
75
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 42 46 21 35 21 / 50 70 10 5 5
WACO, TX 43 53 23 42 18 / 60 50 10 5 5
PARIS, TX 40 43 21 31 15 / 50 80 40 10 5
DENTON, TX 38 42 20 31 17 / 50 80 10 5 5
MCKINNEY, TX 41 43 22 31 16 / 50 80 20 10 5
DALLAS, TX 43 46 22 36 23 / 50 70 10 5 5
TERRELL, TX 43 48 24 35 18 / 50 80 20 10 5
CORSICANA, TX 44 52 23 40 21 / 60 70 10 5 5
TEMPLE, TX 47 56 23 43 20 / 70 40 10 5 5
MINERAL WELLS, TX 38 41 17 35 18 / 50 60 10 5 5
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM NOON TO 9 PM CST TUESDAY FOR
TXZ091>095-100>107.
&&
$$
82/92
AREA FORECAST DISCUSSION...UPDATED
NWS LUBBOCK TX
1017 PM CST MON DEC 24 2012
.UPDATE...
THE AFD YOU HAVE WAITED FOR IS READY BEFORE THE STORM
ALTHOUGH THE FORM IS WEIRD AND LANGUAGE NOT THE NORM.
THE STORM THAT IS ARRIVING IS BECOMING MORE CLEAR...
A FEW SCENARIOS ARE POSSIBLE WITH THE EVENT DRAWING NEAR.
WATER VAPOR SATELLITE SHOWS THE STORM STILL COMING OUR WAY...
SOUTHEAST OF THE FOUR CORNERS IT SPINS TO ARRIVE CHRISTMAS DAY.
THE RAP AND NAM ARE BREAKING OUT SNOW ACROSS THE NORTHWEST
AS EARLY AS 08 TO 10Z WHICH IS WHAT THEY HAVE GUESSED.
285K ISENTROPIC LIFT AND MOISTURE INCREASE BY LATE MORNING...
THE RAP AND NAM SHOW SNOW AMOUNTS THAT MAY WARRANT A WARNING.
MOST FAVORED AREA ARE ACROSS NORTHERN COUNTIES INTO THE PLAINS...
SNOW BANDING IS HINTED AS THE MODELS LOOSE THE REINS.
TEMPERATURE PROFILES ARE STILL EXPECTED TO FALL BELOW FREEZING
WHICH CONCERNS OF A MIX OF RAIN AND SNOW STILL ARE EASING.
THE DEPTH OF COLD AIR INCREASES RAPIDLY AFTER SUNRISE...
STRONG NORTH WINDS COMBINED WITH SNOW COULD BE BLINDING WE ADVISE.
THE BANDS EASE EARLY MORNING AND MORE SNOW LOOKS TO FORM...
ISENTROPIC LIFT KICKS IN NEAR CHILDRESS AND EAST OF THE STORM.
THE AMOUNTS BECOME TRICKY AND THERE IS QUITE A RANGE AS THE LIFT
STARTS TO WEAKEN AND MOISTURE LEVELS START TO CHANGE.
WITH SNOW STARTING OUT WEST AND RAPIDLY MOVING TO THE EAST...
THE LOCATION/RATE OF THE SNOW WILL BE IMPORTANT TO SAY THE LEAST.
IF THE MOST OPTIMISTIC MODELS TURN OUT TO BE CORRECT...
SOME LOCATIONS MAY SEE 4 TO 6 INCHES WHICH WE CANNOT NEGLECT.
WILL HOLD OFF WITH UPGRADING THE ADVISORY TO A WARNING
BUT IT MAY BE REQUIRED WHICH MAY HAPPEN EARLY TUESDAY MORNING.
AS IT STANDS RIGHT NOW THE HUB CITY MAY TURN WHITE
WITH ONE OF THE BANDS APPROACHING CHANCES ARE BETTER THAN SLIGHT.
TRAVEL REMAINS HIGHLY DISCOURAGED IF YOU WANT TO GO NORTH...
ONCE THE SNOW STARTS TO FALL AND THE WIND BLOWS THENCEFORTH.
WE WILL HOLD OUR BREATHS AS WE FINALLY HEAD OUT THE DOOR...
AND ANOTHER SHIFT WILL ARRIVE OUT HERE ON THE OPERATIONS FLOOR.
THE POTENTIAL IS THERE FOR THIS STORM TO CHANGE IT/S MIND...
IF THINGS DRASTICALLY CHANGE THEN THE FORECAST IS IN A BIND.
HOWEVER OUR CONFIDENCE IS INCREASING THAT THE SNOW WILL SOON FALL
WATCHING...OBSERVING...AND FORECAST IN CASE OF A CURVE BALL.
STAY TUNED TO YOUR FAVORITE SOURCES OF WEATHER INFORMATION...
THE SITUATION IS FLUID...CHANGING...AND ALWAYS IN TRANSLATION.
THIS FORECAST SHIFT WILL LEAVE IN A BIT LESS THAN TWO HOURS
HOPING TO WAKE UP TO SEE VERIFICATION IN THE FORM OF SNOW SHOWERS.
FROM THIS FORECASTER TO YOU WHO TRUST US FOR YOUR FORECAST...
I HOPE THIS AFD HELPS YOU AND INFORMS YOU...WITHOUT BEING AGHAST.
MY PURPOSE IS SOLELY TO SHOW YOU WE CARE
AND TO BE METEOROLGICALLY SOUND AND DO IT WITH FLAIR.
TOMORROW SOON WILL ARRIVE AND IT COULD POSSIBLY BE WHITE
SO MERRY CHRISTMAS TO YALL AND TO ALL A GOOD NIGHT!
JORDAN/WFO LUBBOCK
&&
.PREV DISCUSSION... /ISSUED 543 PM CST MON DEC 24 2012/
AVIATION...
CURRENT VFR CONDITIONS WILL GRADUALLY DECREASE INTO MVFR RANGE
TOMORROW MORNING AS A STRONG COLD FRONT PUSHES INTO THE REGION. AT
THE SAME TIME...A STORM SYSTEM WILL MOVE OVER THE REGION RESULTING
IN WINTER PRECIPITATION.
FOR KCDS...MAIN IMPACT WILL BE LOW VISIBILITIES IN BLOWING SNOW
THAT WILL LAST MUCH OF THE MORNING THROUGH AFTERNOON HOURS.
VISIBILITIES WILL DROP INTO MVFR TO IFR RANGE WITH CEILINGS IN THE
MVFR RANGE. FRONT WILL ARRIVE BEFORE SUNRISE/11Z AND INCREASE WIND
SPEEDS FROM THE NORTH AT 25 TO 35 KNOTS AND GUSTS APPROACHING 40
KNOTS. STORM SYSTEM WILL HAVE PUSHED EAST BY MID-DAY BUT
PRECIPITATION WILL SLOWLY END AFTER IT PASSES. CONDITIONS WILL
RETURN BACK TO MVFR TO VFR RANGE AROUND SUNSET.
FOR KLBB...HEAVIEST SNOW IS EXPECTED TO REMAIN NORTH OF THE
REGION HOWEVER BRIEF PERIODS OF SNOW WILL BE POSSIBLE. CONFIDENCE
IS LOW AT THIS TIME AND WILL NOT INCLUDE IN THE TAF AT THIS TIME.
STRONG COLD FRONT WILL ARRIVE AROUND 11Z AND INCREASE THE WIND
SPEED ALSO TO THE 20 TO 30 KNOT RANGE WITH GUSTS APPROACHING 40
KNOTS. DRY CONDITIONS AND STRONG WINDS WILL RESULT IN PERIODS OF
BLOWING DUST THAT WILL REDUCE VISIBILITY SOMEWHAT...HOWEVER IT
SHOULD REMAIN IN THE VFR RANGE. CONDITIONS WILL IMPROVE LATE IN
THE DAY AS WIND SPEEDS DECREASE.
JORDAN
PREV DISCUSSION... /ISSUED 310 PM CST MON DEC 24 2012/
SHORT TERM...
HIGH IMPACT WINTER STORM WILL DEVELOP ACROSS THE PANHANDLE OVERNIGHT
AND MOVE EAST-SOUTHEAST INTO OK ON CHRISTMAS DAY. 12Z AND 18Z MODEL
RUNS CONTINUE FAIRLY GOOD CONTINUITY WITH THE MID-LEVEL TROUGH
DIGGING ACROSS UT THIS AFTERNOON CLOSING OFF AND DEEPENING NORTH OF
LUB BY 12Z TUE. THE SYSTEM THEN EJECTS ALONG OR SOUTH OF THE RED
RIVER CHRISTMAS DAY. THE FAST MOVEMENT OF THE SYSTEM SHOULD LIMIT
THE OVERALL AFFECTS OF ACCUMULATING PRECIP YET THERE IS STILL ENOUGH
LIFT AND INITIAL MOISTURE TRANSPORT INTO THE DEEPENING SYSTEM TO
CAUSE SOME CONCERN.
EXPECT PRECIP TO BREAK OUT NEAR THE NM STATE LINE AFTER MIDNIGHT AS
JET ENERGY DIVES TOWARD THE BASE OF THE TROUGH. THE PRECIP SHIELD
SHOULD BROADEN AND MOVE EAST ACROSS THE NORTHERN SOUTH PLAINS AND
PANHANDLE THROUGH THE MORNING TUE. THE TRACK OF THE UPPER LOW WOULD
PLACE THE FAVORED LOCATION FOR THE HEAVIEST PRECIP NORTH OF A LINE
FROM HEREFORD TO CHILDRESS BUT WITH THE TENDENCY FOR A FEW MODELS TO
CONTINUE TO DIG THE SYSTEM FURTHER SOUTH HAVE BROADENED THE AREA OF
ON INCH OR GREATER SNOW TO INCLUDE THE FAR NORTHERN SOUTH PLAINS.
WHILE THE WESTERN PORTION OF THE WINTER WEATHER ADVISORY AREA MAY
SEE LIMITED SNOW TOTALS...STRONG NORTH WINDS IN THE WAKE OF THE
CANADIAN FRONT WILL CREATE AREAS OF BLOWING SNOW WITH NEAR WHITE-OUT
CONDITIONS EXPECTED FOR THE MAJOR ROADS HEADING INTO THE PANHANDLE.
THE NAM IS FORECASTING 3HR PRESSURE RISES NEAR 10MB ACROSS EASTERN
NM BY 12 TUE SO WIND SPEEDS ARE EXPECTED TO BE ON THE UPPER END OF
THE RANGE PERHAPS PUSHING ADVISORY LEVEL AT TIMES IN THE EARLY
AFTERNOON. THE TRANSITION OF PRECIPITATION FROM RAIN TO SNOW SHOULD
BE VERY QUICK GIVEN THE STRONG DYNAMICAL COOLING AND WET-BULBING
FROM A RELATIVE DRY LOW LEVEL AIRMASS. STILL SIGNIFICANT WARM
ADVECTION IN THE LOW LEVELS WILL BE ONGOING AHEAD OF THE SYSTEM AND
THERE WILL BE A WARM NOSE TO OVERCOME. WOULD NOT BE SURPRISED TO SEE
SOME SLEET OR RAIN SHOWERS AHEAD OF THE MAIN PRECIP IN THE ROLLING
PLAINS VERY EARLY IN THE DAY. AS A RESULT HAVE LEFT A BRIEF WINDOW
OF RA/SN OR PL/SN AHEAD OF THE UPPER LOW AS IT TRACKS EAST BETWEEN
12Z AND 15Z TUE. PRECIP WILL TRANSITION TO ALL SNOW THEN COME TO AN
END RATHER QUICKLY TUE AFTERNOON FROM I-27 EASTWARD BUT ANY
REMAINING MESOSCALE SNOW BANDS ON BACK SIDE OF SYSTEM WILL CONTINUE
TO CREATE AREAS OF VERY LOW VISIBILITY. WE HAVE EXTENDED THE WINTER
WEATHER ADVISORY THROUGH 00Z TO ACCOUNT FOR ANY SLOWER MOVEMENT.
A VERY LOW DIURNAL TEMPERATURE RANGE IS EXPECTED CHRISTMAS DAY WITH
SOME LOCATIONS POSSIBLY REMAINING IN THE TEENS FAR NORTHWEST WITH
STEADY OR DROPPING TEMPERATURES ELSEWHERE. WIND CHILL VALUES COULD
BE NEAR OR SLIGHTLY BELOW ZERO IN A FEW LOCATIONS EARLY IN THE
MORNING.
LONG TERM...
UPPER LOW PRODUCING A WIDE RANGE OF INCLEMENT WEATHER ACROSS THE
SOUTHERN CONUS ON CHRISTMAS DAY PROGGED TO BE ALL THE WAY TO THE
ARKLATEX BY 26/00Z. THIS WILL RESULT IN RAPIDLY IMPROVING CONDITIONS
ACROSS THE FORECAST AREA THROUGH THE EARLY CHRISTMAS EVENING HOURS.
ANY LINGERING SNOWFALL OVER THE SOUTHEAST PANHANDLE OR NORTHERN
ROLLING PLAINS WILL END WHILE CLOUDS AND WINDS WILL ALSO BE ON THE
DECREASE AS A SURFACE PRESSURE RIDGE SETTLES SOUTH ACROSS WEST
TEXAS. THIS WILL LEAD TO A VERY COLD NIGHT ACROSS THE REGION WITH
WEDNESDAY MORNING LOWS FALLING INTO THE 5 TO 15 DEGREE RANGE ACROSS
ALL OF THE FORECAST AREA PER MOS GUIDANCE.
GFS/ECMWF DETERMINISTIC RUNS INDICATE A CONTINUATION OF THE
PROGRESSIVE PATTERN THROUGH THE 7 DAY PERIOD. HIGHLIGHTS WILL BE
ANOTHER UPPER LOW TRANSLATING ACROSS THE MIDWEST BY THE END OF THE
WEEK AND ANOTHER RATHER POTENT LOOKING CLOSED LOW SOMEWHERE ACROSS
THE SW CONUS BY EARLY NEXT WEEK. THE MID WEEK SYSTEM WILL PASS
MAINLY NORTH OF THE FORECAST AREA AND PROBABLY ONLY RESULT IN A
TIGHTENING OF LOWER HEIGHT GRADIENTS TO RESULT IN BREEZY CONDITIONS
ACROSS THE EXTREME SOUTHERN PANHANDLE ON THURSDAY. TEMPERATURES WILL
MODERATE SOME BY THURSDAY WITH SURFACE WINDS BACK AROUND TO THE
SOUTH AND WEST BUT ANOTHER COLD FRONT SHOULD KNOCK OFF AROUND 10
DEGREES OR SO FOR FRIDAY. SHORT WAVE RIDGING WILL THEN ENSUE FOR THE
UPCOMING WEEKEND WITH TEMPERATURES WARMING ONCE AGAIN. SHOULD REMAIN
DRY THROUGH THE LONG TERM PERIOD.
THE LATTER UPPER LOW SHOWN BY BOTH GFS/ECMWF WOULD BE INTERESTING
SHOULD ANY SEMBLANCE OF IT ACTUALLY PAN OUT. BOTH MODELS CLOSE OFF A
LOW AND ADVECT IT TOWARD WEST TEXAS AROUND OR SHORTLY AFTER NEW
YEARS DAY AND BOTH LOOK VERY WET FOR A LARGE PART OF THE SOUTHWEST
US. OF COURSE...WE WILL ONLY BE MONITORING THE MODEL SOLUTIONS FOR
NOW TO SEE IF THIS TREND CONTINUES AND WHAT...IF ANY...IMPACTS THIS
LOW MAY EVENTUALLY HOLD FOR THE FORECAST AREA. JW
&&
.PRELIMINARY POINT TEMPS/POPS...
FRIONA 17 20 7 39 18 / 70 80 10 0 0
TULIA 20 22 8 36 16 / 60 80 10 0 0
PLAINVIEW 21 24 8 38 18 / 50 80 10 0 0
LEVELLAND 27 29 13 39 18 / 40 20 0 0 0
LUBBOCK 24 28 10 39 19 / 30 30 10 0 0
DENVER CITY 35 35 15 41 19 / 10 10 0 0 0
BROWNFIELD 30 32 13 40 19 / 10 10 0 0 0
CHILDRESS 28 28 10 28 16 / 30 80 10 0 0
SPUR 27 29 12 37 19 / 10 30 10 0 0
ASPERMONT 30 30 13 35 19 / 10 40 10 0 0
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 6 PM CST TUESDAY FOR THE FOLLOWING
ZONES: TXZ021>032.
&&
$$
AREA FORECAST DISCUSSION
NWS SPOKANE WA
637 PM PST Wed Dec 26 2012
.SYNOPSIS...
Snow showers will linger across the Inland Northwest tonight,
before dissipating as a storm system moves out of the region. Drier,
colder conditions arrive for the end of the work week. While minor
amounts of snow can be expected from time to time, there are no
major storm systems expected for the next week...with seasonably
cool conditions.
&&
.DISCUSSION...
Update: Satellite and radar as of 615 pm indicated an area of
light snow associated with a weak weather disturbance stretching
from Omak to Odessa and moving east very slowly. As this
disturbance moves east light snow will spread into Spokane this
evening with snow persisting at Pullman and Winchester with weak
west-northwest upslope flow. Latest HRRR and 00z NAM suggest light
snow not reaching the North Idaho Panhandle until after 06z so the
isolated snow shower wording for the evening forecast was removed.
While confidence for light snow spreading east is high amounts
will be very light and may barely measure a hundredth of liquid
precipitation so forecast POPs are in the chance and low end
likely category. With the aforementioned wave east of Wenatchee
and Moses Lake the forecast starts off dry this evening. However
in the late evening and overnight another wave over northwest
Washington will drop southeast increasing chances for snow showers
at Leavenworth, Wenatchee, and Moses Lake. Thus the overnight POPs
were increased for these areas. Snow amounts with this next wave
over Central Washington will be very light with a half inch or
less expected. JW
&&
.AVIATION...
00Z TAFS: the low level air mass is decoupled from the field of
motion aloft with an inversion layer around 060 Kft MSL. This is
promoting widespread stratus with low VFR ceilings at most
locations in the Columbia Basin...with lower ceilings likely
banked against the Cascades at KEAT and as far east as KMWH. These
conditions will change little over the next 24 hours...and tonight
ceilings will likely lower to widespread IFR at most TAF sites by
08-12Z Thursday and remain so through 18Z Thursday...before
lifting slightly to the MVFR category. Aloft a cool upper level
trough is creating elevated instability. This trough will track
east across the forecast area tonight and Thursday morning
triggering scattered to numerous snow showers mainly impacting the
eastern TAF sites tonight and Thursday morning. By Thursday
afternoon after 18-19Z...the upper level wave will move east out
of the area...but the moist and stable boundary layer conditions
will remain promoting continued low MVFR ceilings over the
Columbia Basin. /MJF
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 25 32 25 33 23 33 / 50 20 10 10 10 20
Coeur d`Alene 26 34 25 35 24 34 / 50 40 10 10 10 20
Pullman 29 34 28 36 27 33 / 60 60 20 10 10 10
Lewiston 32 41 31 42 30 40 / 60 50 20 10 0 10
Colville 26 33 26 34 24 35 / 50 10 10 10 20 20
Sandpoint 27 30 27 32 25 33 / 40 40 10 10 20 20
Kellogg 26 30 25 31 24 31 / 50 70 30 10 10 20
Moses Lake 25 34 27 35 26 35 / 30 10 0 10 10 10
Wenatchee 25 32 25 32 26 33 / 50 10 0 10 10 10
Omak 21 30 22 29 25 33 / 70 10 0 10 20 20
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
225 PM CST TUE DEC 25 2012
.SHORT TERM...TONIGHT AND WEDNESDAY.
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW ARCTIC HIGH
PRESSURE CENTERED OVER THE NORTHERN GREAT PLAINS AND NOSING ACROSS
THE WESTERN GREAT LAKES. CLOUDS AND FLURRIES HAVE RETREATED NORTH
OF THE UPPER PENINSULA BORDER EARLY THIS AFTERNOON AND ARE NO LONGER
IMPACTING N-C WISCONSIN. MEANWHILE...LIGHT NE LOW LEVEL FLOW HAS
ALREADY STARTED TO DEVELOP OVER NORTHEAST WISCONSIN AND LAKE CLOUDS
ARE ALREADY PUSHING ACROSS THE FOX VALLEY. SNOW FLURRIES ARE
SHOWING UP ON RADAR JUST OFFSHORE THE KEWAUNEE COAST...AND EVEN WHAT
LOOKS LIKE A MID-LAKE BAND HAS BEEN MOVING EAST OVER CENTRAL LAKE
MICHIGAN. AS DEEPER AND STRONGER NE FLOW DEVELOPS LATER TONIGHT AND
WEDNESDAY...LAKE EFFECT SNOW CHANCES AND AMOUNTS ARE THE MAIN
FORECAST CONCERNS.
TONIGHT...SURFACE HIGH PRESSURE RIDGE AXIS WILL BE EXTENDING ACROSS
NORTHERN WISCONSIN AND LAKE MICHIGAN AT THE START OF THE
EVENING...BUT WILL SHIFT NORTHWARD THROUGH THE NIGHT. AS STRONG LOW
PRESSURE MOVES OVER THE SOUTHERN OHIO VALLEY...WIND DIRECTION WILL
BECOME NORTHEASTERLY FROM THE SURFACE UP TO 700MB. 12Z GRB SOUNDING WAS
PRETTY DRY ABOVE 900MB THIS MORNING...BUT ONCE THE NE FLOW BECOMES
ESTABLISHED...OUR AIR WILL BE COMING FROM NORTHERN LAKE MICHIGAN
WHERE THE 12Z APX SOUNDING WAS CONSIDERABLY MORE SATURATED...UP TO
825MB. SINCE AMPLE CLOUD COVER ALREADY EXISTS OVER NORTHERN LAKE
MICHIGAN...AND SHOWING NO SIGNS OF DISSIPATING...SEE NO REASON WHY
THE LAKE CLOUDS COULD NOT CONTINUE TO PUSH ACROSS THE WESTERN FOX
VALLEY AND POSSIBLY EXPAND INTO CENTRAL WISCONSIN. LAKE EFFECT SNOW
POTENTIAL WILL IMPROVE THROUGH THE NIGHT WHEN 1000-850MB FLOW
STRENGTHENS TO 15 KTS. COMBINED WITH LENGTHENING FETCHES AND DELTA
T/S AROUND 16C...LAKE EFFECT SNOW SHOWERS LOOK LIKELY LATE TONIGHT
OVER E-C AND NE WISCONSIN. THINK IT WILL TAKE AWHILE FOR THE
MULTIPLE BANDS TO DEVELOP WITH WINDS LIGHT THIS EVENING. SO WILL
SHOW ACCUMS UP TO AN INCH OVER E-C WISCONSIN...MAINLY AFTER
MIDNIGHT. ELSEWHERE...CIRRUS WILL INCREASE FROM THE SW AFTER
MIDNIGHT AHEAD OF A NORTHERN STREAM SHORTWAVE. LOWS SLIGHTLY BELOW
ZERO OVER N-C WISCONSIN...TO THE UPPER TEENS NEAR LAKE MICHIGAN.
WEDNESDAY...NORTHEAST FLOW WILL CONTINUE UNABATED FOR THE ENTIRE
DAY. WITH A CIRRUS SHIELD OVERHEAD...DELTA T/S WILL REMAIN AROUND
15C WITH GREAT FETCH LENGTHS AND 1000-850MB WINDS BETWEEN 15-20KTS.
IN ADDITION...AN INCOMING SHORTWAVE TROUGH WILL LIFT INVERSION
HEIGHTS TO NEAR 800MB (PROBABLY UNDERESTIMATED DUE TO LAKE MICHIGAN
MODIFICATIONS) AND CREATE LARGE-SCALE ASCENT...WHICH WILL SUBTLY IMPROVE
LES POTENTIAL. WENT A LITTLE MORE BULLISH WILL SNOWFALL POTENTIAL
DUE TO THESE FACTORS...AND WILL SHOW 1-2 INCHES IN THE FORECAST. AM
CONCERNED THAT THE LONG FETCH LENGTHS AND A PERSISTENT WIND
DIRECTION WILL LEAD TO HIGHER AMOUNTS SINCE THIS COULD LEAD TO
ORGANIZED BANDING. ELSEWHERE...PLENTY OF CIRRUS OVERHEAD WILL CREATE
TO PARTLY SUNNY TO MOSTLY CLOUDY CONDITIONS. HIGHS MAINLY IN THE LOW
TO MID 20S.
.LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY.
LAKE EFFECT SNOW SHOWERS WILL BE DIMINISHING EARLY IN THE PERIOD
AS LOW-LEVEL WINDS BACK AND SURFACE HIGH PRESSURE MOVES IN.
PACIFIC ENERGY MOVES ON SHORE WED AND QUICKLY MOVES INTO MIDWEST
BY LATE IN WEEK. ASSOCIATED SHORTWAVE TROF AND SURFACE WAVE MOVE
ACROSS REGION ON FRIDAY. ENOUGH MOISTURE ASSOCIATED WITH SYSTEM
TO PRODUCE LIGHT COATING OF SNOW ACROSS AT LEAST THE SOUTHERN
THIRD OR SO OF FORECAST AREA.
SEASONAL TEMPS DURING PERIOD AS ARCTIC AIR...FOR THE MOST PART...
REMAINS BOTTLE UP IN CANADA...NORTH AND NORTHEAST OF WI.
&&
.AVIATION...GOOD FLYING CONDITIONS ACROSS MOST OF THE REGION THROUGH
THE REST OF THE AFTERNOON. MVFR CIGS/VSBYS IN LIGHT SNOW OVER N-C
WISCONSIN WILL RETREAT TO THE UPPER PENINSULA BY MID-AFTERNOON.
MVFR STRATUS OVER THE LAKE MICHIGAN SHORELINE IS NOT AS CLEAR CUT.
DESPITE INCOMING HIGH PRESSURE...LIGHT WINDS AND AMPLE INSTABILITY
SEEM TO BE ENOUGH TO SUSTAIN BKN CONDITIONS. AS LIGHT WINDS TURN NE
THIS EVENING...EXPECT THE BKN CIGS TO SURGE ACROSS ALL OF NE
WISCONSIN INCLUDING THE FOX VALLEY. LIGHT FLURRIES WILL LIKELY
GRADUALLY PICK UP IN INTENSITY LATE TONIGHT THROUGH WEDNESDAY
MORNING. SOME MINOR ACCUMULATIONS ARE POSSIBLE BY THE END OF THE
TAF PERIOD...BUT THE SNOW WILL BE LIGHT AND FLUFFY AND EASILY BLOWN
OFF THE RUNWAYS AND AIRCRAFT.
MPC
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MPC/JKL
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1019 PM CST MON DEC 24 2012
UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE
.SHORT TERM...TONIGHT AND TUESDAY.
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A SHORTWAVE
TROUGH EXTENDING FROM NE WISCONSIN TO SOUTHERN LOWER MICHIGAN EARLY
THIS AFTERNOON. COMMA HEAD PRECIP WITH A LITTLE HELP FROM A LIGHT
LAKE EFFECT COMPONENT PRODUCED AREAS OF LIGHT SNOW THAT LINGERED
ACROSS NORTHEAST AND EAST-CENTRAL WISCONSIN THROUGH MID-AFTERNOON
BUT IS CURRENTLY EXITING TO THE EAST. WILL SHOW MOST OF THE PRECIP
ENDING BY 00Z THIS EVENING. IMPROVING CONDITIONS ARE OCCURRING OVER
CENTRAL AND NORTH-CENTRAL WISCONSIN WHERE BREAKS IN THE OVERCAST ARE
GROWING LARGER. HIGH PRESSURE IS BUILDING SOUTHWARD ACROSS THE
NORTHERN PLAINS WHERE SKIES ARE MOSTLY CLEAR AND COLD. THE MAIN
FORECAST CONCERNS INCLUDE THE TIMING OF THE END OF THE PRECIP AND
CLEARING TRENDS TONIGHT.
TONIGHT...THE SHORTWAVE TROUGH WILL BE WELL EAST OF THE REGION OVER
LOWER MICHIGAN AT THE START OF THE PERIOD. RESIDUAL MOISTURE WILL
TAKE AWHILE TO PUSH OUT OF THE REGION...SO WILL START THE EVENING
WITH MOSTLY CLOUDY CONDITIONS WITH A CHANCE OF FLURRIES OVER NE
WISCONSIN. BUT STRONG DRY AIR ADVECTION OVER NORTHWEST WISCONSIN
WILL SLOWLY MOVE SOUTHEAST THROUGH THE NIGHT AND GRADUALLY CLEAR OUT
THE SKIES ACROSS THE MAJORITY OF THE REGION. THE LONE EXCEPTION
WILL BE OVER N-C WISCONSIN WHERE LIGHT NW FLOW WILL CONTINUE TO
GENERATE LAKE EFFECT CLOUDS AND LIGHT SNOW SHOWERS. TEMPS WILL FALL
TO NEAR ZERO OVER THE COLD SPOTS OF LINCOLN COUNTY WHERE SKIES WILL
CLEAR FIRST TO THE MIDDLE TEENS NEAR LAKE MICHIGAN WHERE CLOUDS WILL
CLEAR LAST.
TUESDAY...CANADIAN HIGH PRESSURE WILL BUILD SOUTHEAST ACROSS THE
NORTHERN PLAINS AND NOSE ITS WAY ACROSS THE WESTERN GREAT LAKES.
LIGHT NORTHWEST FLOW WILL CONTINUE OFF LAKE SUPERIOR INTO N-C
WISCONSIN THROUGH THE MORNING...WHICH WILL KEEP SCT FLURRIES...AND
PARTLY TO MOSTLY CLOUDY CONDITIONS THERE. ELSEWHERE...MOSTLY SUNNY
CONDITIONS SHOULD PREVAIL. HIGHS RANGING FROM THE MID TEENS WEST TO
THE MID 20S EAST.
.LONG TERM...TUESDAY NIGHT THRU NEXT SUNDAY.
OVERALL...NO SIGNIFICANT CHANGES TO THE LONG TERM FORECAST. MAIN
FOCUS WAS TO TRY ADD A BIT MORE DETAIL REGARDING LES POTENTIAL
FOR LAKE MICHIGAN COUNTIES FOR WEDNESDAY.
MODELS CONTINUE TO BE IN FAIRLY GOOD AGREEMENT ON OVERALL TRACK OF
SOUTHERN STORM SYSTEM FORECAST TO TRACK TO THE OHIO VALLEY ON
WEDNESDAY. AS PREVIOUSLY FORECAST...THE NORTHERN FRINGE OF STRATIFORM
PRECIPITATION SHIELD WILL JUST CLIP EXTREME SOUTHEAST WISCONSIN
AND THE SOUTHERN PORTION OF LAKE MICHIGAN LATE WEDNESDAY. OTHER
THAN MIDDLE TO HIGH-LEVEL CLOUDS...THE MAIN IMPACT OF THIS SYSTEM
WILL BE TO CREATE A DEEP NORTHEASTERLY WIND FLOW EXTENDING FROM
THE SURFACE UP TO NEAR 700 MB. MAXIMUM OVERWATER BOUNDARY LAYER
FETCH ALSO IN PLACE BY 12Z WEDNESDAY. EXAMINATION OF MODIFIED
FORECAST GFS/NAM SOUNDINGS OVER LAKESHORE COUNTIES INDICATE A
FAIRLY DEEP MOIST AND UNSTABLE LAYER...WITH INVERSION HEIGHTS
APPROACHING 7000 FT AGL OVER WESTERN LAKE MICHIGAN. NAM/GFS ALSO
SUGGEST THAT MOIST LAYER MAY GROW DEEP ENOUGH TO PENETRATE INTO
FAVORABLE DENDRITIC GROWTH ZONE. WATER SURFACE TO 850 DELTA T
VALUES ON THE ORDER OF -16C TO -18C BY 12Z WEDNESDAY OVER THE
NORTHERN HALF OF LAKE MICHIGAN. GFS HAS BEEN FAIRLY CONSISTENT
LAST FEW RUNS...SPITTING OUT AREA OF QPF OVER NORTHERN LAKE
MICHIGAN AFTER 06Z WEDNESDAY AND BRINGING IT ONSHORE BY 12Z
WEDNESDAY. GIVEN OVERALL SYNOPTIC SETUP...NO REASON TO DISCOUNT
SIGNAL FROM GFS. BOTTOM LINE IS FAIRLY DECENT SET-UP FOR LAKE
EFFECT OVER MANITOWOC AND KEWAUNEE COUNTIES STARTING AROUND
DAYBREAK WEDNESDAY AND PERHAPS CONTINUING FOR MUCH OF THE DAY.
GIVEN BOUNDARY LAYER WINDS SPEEDS...WOULD EXPECT MULTIPLE AND SOMEWHAT
LES ORGANIZED LES BANDS RATHER THAN A SINGLE BAND. GIVEN THE
MESOSCALE NATURE OF LES PRECIPITATION WILL LET LATER SHIFTS TRY TO
REFINE THE DETAILS. FELT CONFIDENT ENOUGH AT THIS POINT TO AT
LEAST ADJUST POPS UPWARD INTO THE CHANCE CATEGORY ON WEDNESDAY.
FINALLY...GIVEN DEEP AND PERSISTENT NORHEASTERLY FLOW...ANY LES
BANDS THAT DEVELOP MAY BE ABLE TO PENETRATE AS FAR WEST AS THE FOX
RIVER VALLEY BEFORE WEAKNING. AS OHIO VALLEY STORM SYSTEM
CONTINUES TO MOVE NORTHEAST TO THE EASTERN SEABOARD...BOUNDARY
LAYER WINDS WILL BACK TO OFFSHORE WEDNESDAY NIGHT PUSHING ANY LES
BAND SOUTHWARD. FAIRLY TRANQUIL DAY ON THURSDAY AS WEAK HIGH
PRESSURE RIDGE MOVES ACROSS THE FORTECAST AREA.
THEN BY FRIDAY...SOUTHERN AND NORTHERN STREAM ENERGY BEGIN TO
APPROACH THE CENTRAL PLAINS AND UPPER MISSISSIPPI VALLEY.
UNCERTAINTY REMAINS AS TO HOW THESE FEATURES WILL INTERACT...WITH
CONCENSUS OF GUIDANCE SUGGESTING PERHAPS SOME PHASING OVER THE
OHIO VALLEY FRIDAY NIGHT. REGARDLESS...COMBINATION OF THESE
FEATURES SHOULD BE ABLE TO CREATE WAA ADVECTION REGIME AND DRAW
ADEQUATE MOISTURE NORTHWARD TOWARD THE FORECAST AREA TO GENERATE
BROAD AND GENERALLY LIGHT AREA OF QPF LIKELY TO SPREAD INTO THE
FORECAST AREA LATE ON FRIDAY INTO SATURDAY. LEANING MORE TOWARD
SOMEWHAT LESS ORGANIZED INVERTED TROUGH LOOK OF THE ECMWF AND
OPERATIONAL GFS FOR FRIDAY SYSTEM. INVERTED TROUGH AND CYCLONIC
FLOW MAY HANG BACK ACROSS THE WESTERN GREAT LAKES INTO
SATURDAY...THUS CONTINUE CHANCE POPS UNTIL THEN AS PER PREVIOUS
FORECAST.
DAYTIME TEMPERATURES SHOULD GRADUALLY MODERATE BY THE END OF THE
WEEK TO NEAR OF PERHAPS SLIGHTLY ABOVE NORMAL.
&&
.AVIATION...EVENING GRB RAOB SHOWS PLENTY OF MOISTURE IN THE LOWER
LEVELS TONIGHT. SUPPORTS EVENING TREND OF LINGERING MVFR CIGS
ACROSS MUCH OF THE STATE TONIGHT AND EVEN INTO TUESDAY. HAVE
ALREADY TRENDED MORE PESSIMISTIC WITH THE CLOUDS TONIGHT.
TDH
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
259 AM MST THU DEC 27 2012
.SHORT TERM...A BROAD CIRCULATION CENTER WAS LOCATED FM ERN WY
INTO WRN NE EARLY THIS MORNING AND WILL MOVE SLOWLY EASTWARD THRU
TONIGHT. OVERALL THE FLOW ALOFT IN THE MTNS WILL BE WNW WITH
FAVORABLE OROGRAPHICS THRU TONIGHT. LAPSE RATES WILL AVERAGE
AROUND 7 C/KM WITH MOISTURE DEPTH AROUND 300 MB SO SHOULD SEE
PERIODS OF SNOW WITH ACCUMULATIONS MEETING ADVISORY CRITERIA. OVER
NERN CO IT APPEARS ANY PCPN THRU LATE AFTN WILL BE CONFINED TO
THE FAR NERN CORNER MAINLY THIS MORNING. HOWEVER BY THIS EVENING A
DISTURBANCE WILL MOVE SSE ACROSS THE AREA WITH WEAK UPSLOPE FLOW
DEVELOPING ALONG THE FRONT RANGE. THUS COULD SEE A BREIF PERIOD OF
LIGHT SNOW IN AND NR THE FOOTHILLS AND OVER THE PALMER DIVIDE IN
THE 00Z-06Z TIMEFRAME. HAVE INCREASED POPS TO CHC CATEGORY HOWEVER
CONFIDENCE IS NOT HIGH ENOUGH AT THIS POINT TO GO LIKELY. AS FAR
AS HIGHS THIS AFTN READINGS ACROSS NERN CO WILL BE MAINLY IN THE
20S. AROUND DENVER COULD SEE A 10 DEGREE SPREAD IN HIGHS AS
INVERSION MAY BREAK OVER THE SRN SUBURBS ALLOWING FOR HIGHS IN
THE LOWER TO MID 30S WHILE OTHER AREAS AROUND DENVER STAY IN THE
MID TO UPPER 20S.
.LONG TERM...ZONAL FLOW IS PROGGED OVER THE CWA FRIDAY...THEN
NORTHWESTERLY FLOW ALOFT IS PROGGED FOR FRIDAY NIGHT. AN UPPER
RIDGE IS PROGGED TO MOVE ACROSS COLORADO SATURDAY. THE FLOW ALOFT
IS ZONAL ON SATURDAY...THEN SOUTHWESTERLY SATURDAY NIGHT. THE QG
VERTICAL VELOCITY FIELDS HAVE DOWNWARD SYNOPTIC SCALE ENERGY OVER
THE CWA FRIDAY INTO SATURDAY MORNING. THE REST OF SATURDAY AND
SATURDAY NIGHT HAS WEAK UPWARD MOTION PROGGED. THE BOUNDARY LAYER
FLOW LOOKS TO BE DOMINATED BY DOWNSLOPING FRIDAY INTO SATURDAY
MORNING...THEN MORE NORMAL DUIRNAL PATTERNS ARE PROGGED FOR THE
REST OF SATURDAY AND SATURDAY NIGHT. FOR MOISTURE...THERE IS SOME
AROUND ON FRIDAY...ACTUALLY PRETTY DEEP OVER THE MOUNTAINS IN THE
MORNING. DRYING KICKS IN BY AFTERNOON...CONTINUING FRIDAY
EVENING. THE REST OF FRIDAY NIGHT AND SATURDAY LOOK PRETTY DRY FOR
ALL AREAS...MAYBE SOME HIGH CLOUDS. MOISTURE INCREASES SATURDAY
NIGHT...MOSTLY THE UPPER LEVEL TYPE. THE QPF FIELDS SHOW SMALL
AMOUNTS OF MEASURABLE PRECIPITATION ON FRIDAY IN THE MOUNTAINS
ONLY. FRIDAY NIGHT THROUGH SATURDAY NIGHT ARE DRY. SO FOR POPS
...WILL GO WITH 30-60%S IN THE MOUNTAINS ON FRIDAY. THERE IS
FAIRLY DECENT MOISTURE AND SOME HELP FROM OROGRAPHICS. JUST MINOR
POPS IN THE MOUNTAINS FRIDAY EVENING. NO POPS ELSEWHERE THROUGH
THE PERIODS. FOR TEMPERATURES...FRIDAY`S HIGHS ARE A TAD WARMER
THAN TODAY`S. SATURDAY`S WARM UP 2-4 C FROM FIRDAY`S HIGHS. FOR
THE LATER DAYS...SUNDAY THROUGH WEDNESDAY...SOUTHWESTERLY FLOW
ALOFT IS PROGGED SUNDAY INTO MONDAY. MODELS SHOW AN UPPER TROUGH
TO MOVE ACROSS THE FORECAST AREA LATE MONDAY INTO TUESDAY MORNING.
THE ECMWF AND GFS SHOW THE TROUGH IN PRETTY FAIR AGREEMENT.
HOWEVER...THE ECMWF HAS A CLOSED CIRCULATION AT IT`S BASE...THE
GFS DOES NOT HAVE THIS. SO BY TUESDAY...THE GFS HAS THE TROUGH
THROUGH THE CWA...WHILE THE ECMWF HAS A CLOSED CIRCULATION SOUTH
OF COLORADO. THIS UPPER LOW IS CENTERED NEAR EL PASO TEXAS LATE
WEDNESDAY. MOISTURE IS WAY DIFFERENT ON THE TWO MODELS....THE GFS
SHOWS QUITE A BIT OF MOISTURE FOR SUNDAY NIGHT AND MONDAY. THE
ECMWF DOWSN`T GET MOISTURE INTO THE CWA UNTIL MONDAY NIGHT AND
TUESDAY. POOR AGREEMENT HERE. LATER TUESDAY THROUGH WEDNESDAY LOOK
DRY ON BOTH MODELS. WILL KEEP POPS SOMEWHAT AT BAY DUE TO THE
UNCERTAINTIES.
&&
.AVIATION...STRATUS HAS REMAINED JUST TO THE NORTH OF THE AIRPORT OVER
SRN WELD COUNTY THE ENTIRE NIGHT AND SO FAR HAS SHOWN NO SIGNS OF
SPREADING SOUTH AT THIS POINT. BOTH THE RAP AND THE HRRR KEEP SHOW
SFC WINDS BECOMING MORE SLY BY SUNRISE SO IF THAT OCCURS THEN
STRATUS MAY NOT AFFECT THE AIRPORT. COULD SEE SOME PATCHY FOG
HOWEVER VISBILITIES LOOK TO BE AOA 5 MILES AT THIS POINT. BY
MIDDAY SFC WINDS WILL BECOME MORE ELY AND STAY THAT WAY THRU EARLY
EVENING. AS TALKED ABOUT ABV THERE COULD BE SOME LIGHT SNOW FOR A
FEW HOURS BETWEEN 00Z AND 06Z AS DISTURBANCE MOVES SSE ACROSS THE
AREA. AT THIS POINT ANY ACCUMULATION SHOULD BE LESS THAN AN INCH
IF SNOW DEVELOPS.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 11 PM MST THIS EVENING FOR COZ031-
033-034.
&&
$$
SHORT TERM...RPK
LONG TERM....RJK
AVIATION...RPK
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
439 AM EST Thu Dec 27 2012
.NEAR TERM [Through Tonight]...
Quiet weather is shaping up for today as cool high pressure builds
into the area. Morning cloud cover should gradually erode during
the day with skies expected to be mostly clear areawide by
tonight. The cool airmass is expected to keep high temperatures
below average this afternoon.
Heading into tonight, as the surface ridge moves closer to the
area, decent radiational cooling conditions are expected. Lows are
expected to bottom out near freezing over a large portion of the
area away from the coast with the coldest readings over the
southeast big bend. Areas of frost look likely away from the coast
and are mentioned in the forecast.
&&
.SHORT TERM [Friday Through Saturday]...
The pattern is expected to remain progressive through the short
term with the next shortwave arriving late Friday into Saturday
morning. An area of low pressure is expected to develop near the
Gulf coast and move eastward through the area. Model agreement is
fairly good on the timing of this system, so PoPs were bumped up
to 70-80 percent on Friday night. A warm front is expected to
straddle the coast with the greatest surface based instability
remaining just offshore. However, there appears to be enough
elevated instability to keep some chances of thunder over most of
the area. In fact, if the 00z NAM instability forecast verifies,
then there could be some stronger storms over the coastal waters
with favorable shear for organized convection. It is worth keeping
an eye on this to make sure there doesn`t end up being a low end
threat for a stronger storm along the coastline, but right now the
threat seems limited.
&&
.LONG TERM [Saturday Night through next Thursday]...
The period will begin with another Sfc Low exiting our region
quickly to the NE with a strong and cold Ridge of High Pressure
building in from the NW. This Ridge is expected to strengthen to
between 1030 and 1035mb and will be situated right over the CWA on
Sunday and Monday. This will set the stage for a possible short
duration light freeze on Sunday morning, with a likely long
duration light freeze (with a poss. Hard Freeze in some colder
locations) for Monday morning. Daytime highs on Sun. and Mon. will
also be held down several degrees below climo. For the remainder
of the period, however, an extended period of unsettled conditions
appears likely, as a series of weak waves of low pressure ride
E-NE along an elongated boundary. This boundary will be fairly
close to stationary over our CWA Mon. Night through Wed. Night, as
it will be essentially trapped between a strong Upper Ridge over
the SE Gulf of Mexico, and a weak Upper Trof swinging in from the
NW. At this time, this setup would favor periods of beneficial
rain over our area, with any Tstms appearing unlikely. It should
be noted, however, that the GFS and CMC are in good agreement with
this scenario (which we are fcsting), while the past 2 runs of the
ECMWF are much slower with moisture advection, holding off the
next batch of rain until Wed. Night and Thurs.
&&
.AVIATION...
[Through 06Z Friday] A rather large area of MVFR level Cigs have
overtaken all of the terminals except ECP early this morning, but it
will only a matter of time before these low clouds envelop ECP as
well. This setup is shown very well on the NARRE and HRRR Hi-Res
Models, while the numerical guidance from the large scale models is
way off base once again. These Cigs should begin to break and
scatter out by 14Z this morning, with VFR conditions and light winds
expected to prevail at all of the Taf Sites for the remainder of the
period.
&&
MARINE...
Winds and seas will continue diminishing today as high pressure
builds south toward the marine area. The next storm system will
begin to develop across the Gulf on Friday evening with winds and
seas expected to reach advisory levels this weekend.
&&
.FIRE WEATHER...
Although afternoon relative humidities will be noticeably lower
today and Friday, they are not expected to be low enough (and ERCs
will not be high enough) to cause any concerns. With another
wetting rainfall expected on Friday night and Saturday, no Red
Flag concerns are expected for the next several days.
&&
.HYDROLOGY...
Area rivers are expected to remain below flood stage for the next
several days. A general half inch to one inch of rain is expected on
Friday night into Saturday with the highest amounts expected to be
near the coast.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 56 32 62 53 67 / 0 0 10 80 40
Panama City 55 41 62 56 65 / 0 0 20 80 30
Dothan 52 35 60 50 61 / 0 0 10 70 30
Albany 54 32 60 46 64 / 0 0 10 70 40
Valdosta 55 32 62 51 64 / 0 0 10 80 60
Cross City 58 31 63 53 70 / 0 0 0 80 60
Apalachicola 54 40 61 57 68 / 0 0 20 80 40
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...FREEZE WATCH from late tonight through Friday morning for
Inland Dixie-Inland Taylor-Lafayette-Madison.
GA...None.
AL...None.
GM...None.
&&
$$
Near Term/Short Term/Marine/Hydrology...DVD
Long Term/Aviation/Fire Wx...Gould
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
415 AM EST THU DEC 27 2012
...MODERATE RISK OF RIP CURRENTS THROUGH THIS AFTERNOON FOR SUNCOAST
BEACHES...
...FREEZE WATCH LATE TONIGHT THROUGH EARLY FRIDAY MORNING FOR LEVY
AND CITRUS COUNTIES...
.SYNOPSIS...
08Z WATER VAPOR AND H4 RAP ANALYSIS SHOWING AN ACTIVE UPPER LEVEL
PATTERN IN PLACE ACROSS THE CONUS EARLY THIS MORNING. FROM WEST TO
EAST...NORTHERN STREAM FLOW CARVES OUT LONGWAVE TROUGHING FROM THE
PACIFIC COAST THROUGH THE INTERMOUNTAIN WEST BEFORE RIDGING BACK TO
THE NORTH OVER THE CENTRAL PLAINS/UPPER MIDWEST. THE FLOW THEN
SHARPLY TURNS BACK TO THE SOUTH INTO A NEGATIVELY TILTED LONGWAVE
TROUGH PIVOTING UP THE EASTERN SEABOARD. THIS IMPRESSIVE ENERGY IS
SUPPORTING AN ORGANIZED SURFACE LOW NEAR THE SOUTHERN NEW ENGLAND
COAST AND A WIDE SWATH OF COASTAL RAIN/INLAND SNOW. CLOSER TO
HOME...EASTERN U.S. TROUGH HAS EXITED OUR REGION WITH A ZONAL FLOW
NOW IN PLACE OVER THE GULF / FL PENINSULA. THIS ZONAL FLOW WILL HOLD
FOR THE NEXT 24/36 HOURS...AND EVEN RIDGE UP SLIGHTLY IN RESPONSE TO
HEIGHT FALLS EXPANDING ACROSS THE SOUTHERN PLAINS TOWARD THE LOWER
MS VALLEY.
AT THE SURFACE...WEDNESDAYS COLD FRONT IS NOW WELL TO THE EAST AND
SOUTH OF THE FORECAST AREA...AND A DRIER AND COOLER AIRMASS HAS
ARRIVED IN ITS WAKE. TIGHT GRADIENT THAT HAS BEEN IN PLACE SINCE THE
FRONTAL PASSAGE IS BEGINNING TO WEAKEN AS CONTINENTAL HIGH PRESSURE
CURRENTLY CENTERED OVER THE LOWER MS VALLEY BEGINS TO RIDGE IN FROM
THE NORTHWEST. SEASONABLY COOL TEMPERATURES OUT THERE THIS
MORNING...BUT NOT COLD...AS THE TIGHTER GRADIENT HAS HELPED KEEP
READINGS UP. ONLY EXCEPTION IS UP TOWARD CITRUS/LEVY/SUMTER WHERE
WINDS HAVE ALREADY SLACKENED AND COLDER LOCATIONS ARE IN THE 30S.
&&
.SHORT TERM (TODAY THROUGH SATURDAY)...
TODAY/TONIGHT...FAIR AND GENERALLY COOL CONDITIONS EXPECTED. A DRY
LOW/MID LEVEL COLUMN AND LACK OF ANY SYNOPTIC FORCING WILL KEEP RAIN
CHANCES NEAR ZERO INTO FRIDAY MORNING. SEEING AN INTERESTING THERMAL
STRUCTURE IN THE WAKE OF WEDNESDAYS COLD FRONT. MOST IMPRESSIVE CAA
HAS OCCURRED IN THE LOWER LEVELS AND IN FACT THE 850MB TEMPS WILL BE
WARMER FOR MOST OF US TODAY THAN THE READINGS AT 925-950MB. THIS IS
A THERMAL PROFILE WHICH IS MORE REPRESENTATIVE OF THE AIRMASS BEHIND
AN ARCTIC FRONT...EVEN THOUGH THIS ONE CERTAINLY WAS NOT. LESS
EFFICIENT MIXING AS THE RIDGE BUILDS IN AND THE COOLER TEMPS JUST
ABOVE THE SURFACE WILL KEEP OUR TEMPS BELOW NORMAL. AFTERNOON HIGHS
WILL STRUGGLE TO REACH THE LOWER 60S ALONG AND NORTH OF THE I-4
CORRIDOR AND MID 60S TO PERHAPS 70 FURTHER SOUTH. RIDGE AXIS WILL BE
ALIGNED DOWN THE PENINSULA TONIGHT SETTING UP DECENT RADIATIONAL
COOLING CONDITIONS. TEMPERATURES SHOULD DROP QUICKLY THIS
EVENING...SO BUNDLE UP IF HEADED OUT. BY MORNING...UPPER 30S TO
LOWER 40S WILL BE COMMON AWAY FROM THE COAST...AND EVEN SOME
SUB-FREEZING TEMPS FOR NORMALLY COLDER LOCATIONS FROM BROOKSVILLE
NORTHWARD. WILL BE WATCHING A SLOW INCREASE IN HIGH LEVEL MOISTURE
AFTER MIDNIGHT. AT THIS POINT...THIS MOISTURE IS NOT ANTICIPATED TO
HAVE MUCH IMPACT ON THE TEMP DROP...BUT WILL NEED TO BE WATCHED
CLOSELY IN CASE IT ARRIVES SOONER THAN CURRENTLY THOUGHT. HAVE
ISSUED A FREEZE WATCH FOR LEVY AND CITRUS COUNTIES FOR LATE
TONIGHT...AS THESE ZONES STAND THE BEST CHANCES AT ANY DURATION OF
SUB-FREEZING TEMPS. ELSEWHERE...WITH SMALL DEWPOINT DEPRESSION AND
LIGHT WINDS...HAVE ADDED PATCHY/AREAS OF FROST TO THE GRIDS FOR
LOCATIONS FORECAST TO REACH 36 DEGREES OR LOWER.
FRIDAY/FRIDAY NIGHT...FAIR AND DRY CONDITIONS EXPECTED FOR THE
DAYLIGHT HOURS. NOT QUITE AS MUCH SUNSHINE THOUGH AS HIGH LEVEL
CLOUDS WILL BE ON THE INCREASE. UPPER LEVEL TROUGH TO OUR WEST WILL
BE APPROACHING THE NORTHERN GULF COAST WITH WEAK CYCLOGENESIS
COMMENCING ALONG THE UPPER TX/LA COAST. A WARM FRONTAL FEATURE WILL
BE DEVELOPING EASTWARD FROM THIS SURFACE REFLECTION TO THE NE GULF.
LATE IN THE DAY / EVENING HOURS...LOW LEVEL UPGLIDE ALONG THE
290-300K SURFACES ASSOCIATED WITH THIS FRONT WILL QUICKLY MOISTEN
THE LOWER LEVELS. THIS UPGLIDE / WAA (WARM AIR ADVECTION) PATTERN
SHOULD BEGIN TO DEVELOP SHOWERS ACROSS THE COASTAL WATERS EARLY IN
THE EVENING...AND THEN TOWARD LAND LATE EVENING. NUMERICAL GUIDANCE
IS OFTEN TOO SLOW TO MOISTEN AND DEVELOP QPF DURING UPGLIDE EVENTS
AND HAVE BROUGHT IN SHOWER CHANCES A BIT EARLIER WITH THIS FORECAST
PACKAGE. BEST COVERAGE OF SHOWERS FRIDAY NIGHT IS LIKELY TO BE OVER
THE NORTHERN HALF OF THE AREA WHERE WAA WILL BE MAXIMIZED. SHOWALTER
INDICES OFF THE GFS/ECMWF ARE AROUND ZERO FRIDAY NIGHT...SUGGESTING
SOME THUNDER POTENTIAL. LOW TEMPERATURES FRIDAY NIGHT WILL LIKELY BE
IN THE LATE EVENING...AND THEN RISE AFTER MIDNIGHT IN RESPONSE TO
THE NORTHWARD TRANSLATION OF THE WARM FRONT.
SATURDAY...SURFACE LOW PRESSURE TRACKS FROM THE FL PANHANDLE TO OFF
THE GA/SC COASTLINE DURING THE DAY. TRAILING COLD FRONT WILL SWING
ACROSS THE FORECAST AREA DURING THE DAYLIGHT HOURS. BROAD SWATH OF
WEAK SYNOPTIC SUPPORT AHEAD OF THE UPPER TROUGH AND LOW LEVEL FOCUS
ALONG THE FRONT SHOULD SUPPORT A BAND OF SHOWERS AND STORMS TO
ACCOMPANY THE FRONT. BAND OF CONVECTION SHOULD BE MOST ORGANIZED
FROM THE TAMPA BAY / SARASOTA REGION NORTHWARD WHERE SYNOPTIC
FORCING WILL BE GREATEST. ALTHOUGH STILL EXPECT SHOWERS AND STORMS
FURTHER SOUTH AND EAST...THE BAND SHOULD BE THINNING OUT WITH LESS
FORCING AND AVAILABLE MOISTURE. A STRONGER THUNDERSTORM CAN NOT BE
RULED OUT ON SATURDAY...HOWEVER INSTABILITY AND WIND FIELDS SUGGEST
THE THREAT OF ORGANIZED SEVERE WEATHER IS LOW.
&&
.LONG TERM (SATURDAY NIGHT THROUGH NEXT WEDNESDAY)...
MODELS ARE IN GOOD AGREEMENT THROUGH TUESDAY SO FORECAST CONFIDENCE
THROUGH THEN IS HIGHER THAN NORMAL. AFTER THAT...THE GFS AND ECMWF
PART WAYS IN THE HANDLING OF A CUTOFF LOW OVER THE SOUTHWESTERN
STATES. THE GFS IS LESS CUTOFF AND THEREFORE MORE PROGRESSIVE...
BRINGING A POTENT UPPER-LEVEL TROUGH AND ASSOCIATED FRONTAL BOUNDARY
INTO THE REGION ON WEDNESDAY. THE ECMWF HAS MORE OF A SPLIT
FLOW...LEAVING THE CUTOFF LOW TO MEANDER UNTIL LATE NEXT WEEK.
EITHER SOLUTION IS POSSIBLE SINCE THE TROUGH THAT WILL BE PARENTING
THE CUT-OFF LOW WILL ONLY BE REACHING THE WEST COAST OF THE U.S. ON
FRIDAY. SINCE WE HAVE BEEN IN A FAIRLY PROGRESSIVE PATTERN FOR A
WHILE NOW...WILL INITIALLY SIDE WITH THE FASTER GFS. I WOULD NOT BE
SURPRISED IF WE NEED TO SLOW THE FRONT DOWN IN LATER FORECASTS.
AS FAR AS THE DETAILS GO...THE WEEKEND COLD FRONT WILL BE THROUGH
THE AREA SUNDAY NIGHT WITH COOLER AND DRIER AIR MOVING IN BEHIND IT.
EXPERIMENTAL ECMWF MOS GUIDANCE AND THE MEX HAVE POPS BELOW 15
PERCENT FOR OUR AREA SATURDAY NIGHT...SO REMOVED THE LINGERING
SHOWERS IN OUR SOUTHERN ZONES. AFTER THAT...IT STAYS DRY THROUGH
TUESDAY WITH JUST A SLIGHT CHANCE OF SHOWERS ENTERING OUR NORTHERN
ZONES ON WEDNESDAY.
WE WILL START OFF A BIT ON THE CHILLY SIDE BEHIND THE COLD FRONT ON
SUNDAY WITH HIGHS ONLY NEAR 60 NORTH...MID 60S AROUND TAMPA BAY AND
UPPER 60S SOUTH. THIS WILL BE FOLLOWED BY A COOL NIGHT WITH SOME 30S
OVER THE NATURE COAST SUNDAY NIGHT INTO EARLY MONDAY MORNING.
OTHERWISE WE ARE LOOKING FOR FAIRLY TYPICAL TEMPERATURES FOR LATE
DECEMBER AND EARLY JANUARY WITH HIGHS IN THE 60S AND 70S AND LOWS IN
THE 40S AND 50S.
&&
.AVIATION...
SOME STRATOCUMULUS CLOUDS WITH BASES BETWEEN 2000 AND 3000 FEET
CONTINUES RIGHT ALONG THE COAST. THIS COULD BRING OCCASIONAL MVFR
CEILINGS MAINLY TO PIE THROUGH THE MORNING HOURS TODAY.
OTHERWISE...VFR CONDITIONS EXPECTED.
&&
.MARINE...
LINGERING ADVISORY LEVEL CONDITIONS EARLY THIS MORNING WILL
GRADUALLY DIMINISH THROUGH THE DAY AS HIGH PRESSURE RIDGES DOWN INTO
THE EASTERN GULF OF MEXICO. WINDS AND SEAS WILL BUILD AGAIN LATER
FRIDAY INTO FRIDAY NIGHT AHEAD OF OUR NEXT COLD FRONT. THIS FRONT
WILL CROSS THE EASTERN GULF OF MEXICO DURING SATURDAY. WINDS WILL
SHIFT TO THE NORTHWEST AND NORTH BEHIND THIS FRONT AND ONCE AGAIN
INCREASE TO ADVISORY LEVELS FOR THE SECOND HALF OF THE UPCOMING
WEEKEND.
&&
.FIRE WEATHER...
SURFACE HIGH PRESSURE WILL KEEP CONDITIONS DRY THROUGH FRIDAY.
RELATIVE HUMIDITY VALUES WILL DROP INTO THE LOWER/MID 30S AWAY FROM
THE COAST THIS AFTERNOON. A FIRE DANGER STATEMENT HAS BEEN ISSUED
FOR POLK AND LEE COUNTIES WHERE THE COMBINATION OF LOW RELATIVE
HUMIDITY AND ERC VALUES ABOVE 30 ARE MET. A SLOW MOISTENING OF THE
LOW LEVELS WILL BEGIN FRIDAY...ALTHOUGH INLAND AREAS OF THE NATURE
COAST ZONES MAY STILL RELATIVE HUMIDITY DROP TOWARD 35 PERCENT.
SATURDAY WILL SEE RELATIVE HUMIDITY WELL ABOVE CRITICAL LEVELS ALONG
WITH A GOOD CHANCE FOR SHOWERS AND STORMS AHEAD OF A COLD FRONT.
DRIER AND COOLER WEATHER WILL RETURN TO THE REGION BY SUNDAY BEHIND
THIS FRONT.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 62 44 70 63 / 0 0 10 50
FMY 68 47 76 65 / 0 0 10 20
GIF 64 39 73 58 / 0 0 0 40
SRQ 63 44 71 63 / 0 0 10 40
BKV 61 34 70 57 / 0 0 10 60
SPG 61 50 68 64 / 0 0 10 50
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...BEACH HAZARDS STATEMENT THROUGH THIS EVENING FOR CHARLOTTE-
HILLSBOROUGH-LEE-MANATEE-PINELLAS-SARASOTA.
HIGH SURF ADVISORY UNTIL 7 AM EST THIS MORNING FOR
CHARLOTTE-HILLSBOROUGH-LEE-MANATEE-PINELLAS-SARASOTA.
FREEZE WATCH FROM LATE TONIGHT THROUGH FRIDAY MORNING FOR
CITRUS-LEVY.
GULF WATERS...SMALL CRAFT ADVISORY UNTIL 11 AM EST THIS MORNING FOR
BONITA BEACH TO ENGLEWOOD OUT 20 TO 60 NM-ENGLEWOOD
TO TARPON SPRINGS OUT 20 TO 60 NM.
SMALL CRAFT ADVISORY UNTIL 7 AM EST THIS MORNING FOR
BONITA BEACH TO ENGLEWOOD OUT 20 NM-ENGLEWOOD TO
TARPON SPRINGS OUT 20 NM-TARPON SPRINGS TO SUWANNEE
RIVER OUT 20 TO 60 NM.
&&
$$
SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA
LONG TERM/AVIATION...JILLSON
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
354 AM CST THU DEC 27 2012
.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
FORECAST CONCERNS THROUGH THIS PERIOD ARE SNOWFALL CHANCES AND
AMOUNTS FOR TODAY AND TONIGHT...THEN TEMPERATURES INTO THE
WEEKEND.
AT 08Z...WATER VAPOR IMAGERY SHOWED THE STRONG LOW PRESSURE SYSTEM
IMPACTING THE EAST COAST CENTERED OVER EASTERN VIRGINIA. RIDGING
WAS SITUATED OVER THE MISSISSIPPI RIVER VALLEY AS A FAIRLY LARGE
TROUGH COVERING THE WESTERN HALF OF THE CONUS. COMING OUT OF THE
TROUGH WAS AN UPPER LOW OVER EASTERN WYOMING...WHILE A PV ANOMALY
WAS SEEN OVER EASTERN COLORADO MOVING TOWARDS WESTERN NEBRASKA.
LOCALLY...RADAR ECHOES SPANNED ACROSS THE EASTERN PANHANDLE INTO
NORTHWEST NEBRASKA...WITH MORE CONVECTIVE LOOKING ECHOES OVER
CENTRAL NEBRASKA. NO PRECIPITATION WAS BEING REPORTED WITH THE
EASTERN ACTIVITY WHILE KAIA AND KSNY IN THE PANHANDLE HAD REPORTED
LIGHT SNOW BEING JUST OUTSIDE OF THE MAIN SNOW BAND. MODELS WOULD
INDICATE THE 700MB LOW OVER THE WESTERN PANHANDLE. THERE WAS A
GOOD MOISTURE FEED JUST TO THE EAST OF THE LOW WHICH HAD ITS
PRIMARY FOCUS INTO NORTHWEST NEBRASKA. THE RAP MODEL ALSO WAS
INDICATING SOME FRONTOGENETICAL FORCING AT 700 TO 600MB IN THIS SAME
AREA...WHICH WOULD FIT WITH WHAT IS ONGOING.
AS THE MORNING PROGRESSES...THE UPPER LOW OVER WYOMING WILL SHIFT
EAST INTO NORTH CENTRAL NEBRASKA AROUND MID-DAY THEN CONTINUE EAST
ALONG THE SOUTH DAKOTA/NEBRASKA BORDER INTO TONIGHT. ISENTROPIC
SURFACES FROM ROUGHLY 275K TO 290K ALL SHOWING DECENT LIFT AS WELL
AS MOISTURE TRANSPORT THROUGH THE MORNING /MAINLY OVER NORTHERN
NEBRASKA/...WHICH THEN SHIFTS EAST THIS AFTERNOON. HAVE ADJUSTED
PRECIPITATION CHANCES IN THIS FORECAST TO INCLUDE THE HIGHEST
CHANCES OVER THE PANHANDLE AND NORTHWEST NEBRASKA THIS
MORNING...THEN INTO NORTH CENTRAL NEBRASKA THIS AFTERNOON AS THE
WHOLE SYSTEM MOVES EAST. CONTINUED THE CHANCES OVER SOUTHWEST
NEBRASKA TODAY...BUT CONFIDENCE IS MUCH LESS IN THESE AREAS AND
DID BACK OFF ON CHANCES A BIT. REASONING FOR THIS IS THAT THIS
AREA WILL BE IN A FAVORABLE LOCATION FOR DRY AIR TO COME INTO THE
SYSTEM AROUND THE UPPER LOW...ALSO THE PV ANOMALY OVER COLORADO
HAS GOOD DARKENING IN THE WATER VAPOR IMAGERY INDICATING GOOD DRY
AIR ASSOCIATED WITH IT. AS THIS MOVES INTO SOUTHWEST NEBRASKA...IT
SHOULD LIMIT THE SNOWFALL. WILL PROBABLY SEE SOME SNOW IN THESE
AREAS THROUGH THE DAY...BUT BELIEVE IT WILL BE QUITE LIGHT AND
WILL NOT LAST LONG SO VERY LITTLE IF ANY ACCUMULATION IS EXPECTED.
IF IN FACT THIS OCCURS...THE FORECAST WILL LIKELY NEED TO BE
UPDATED TO REFLECT THE LOWER CHANCES FOR MEASURABLE SNOWFALL IN
THESE AREAS.
THE SYSTEM WILL NOT BE REAL FAST MOVING OUT OF THE LOCAL
AREA...WHICH WILL KEEP SNOW FALLING ACROSS NORTH CENTRAL NEBRASKA
TONIGHT BEFORE EXITING COMPLETELY ON FRIDAY. THERE HAS BEEN GOOD
MODEL AGREEMENT WITH KEEPING THE HIGHER SNOWFALL AMOUNTS JUST EAST
OF THE FORECAST AREA...MAINLY ALONG AND EAST OF HIGHWAY 14.
SOUNDINGS CONTINUE TO SHOW THE ENTIRE SATURATED LAYER /SURFACE
THROUGH 600MB/ IN THE DENTRITIC GROWTH ZONE...SO USED HIGH SNOW
RATIOS VARYING FROM 18:1 TO 23:1. EVEN WITH THIS...STORM TOTAL
SNOW AMOUNTS ACROSS HOLT AND BOYD COUNTIES ONLY SHOWING 2 TO 3
INCHES WITH A FEW LOCALIZED AREAS ABOVE 3 INCHES. GOING EAST OF
THE AREA AMOUNTS IN EXCESS OF 3 INCHES ARE LIKELY. WINDS SHOULD BE
FAIRLY LIGHT TODAY UNDER 15 MPH SO EVEN WITH THE HIGH SNOW
RATIOS GIVING HIGHER SNOW AMOUNTS DON/T FEEL THE IMPACTS WILL BE
HIGH SO WILL NOT PUT OUT AN ADVISORY FOR TODAY AND TONIGHT.
COLD AIR WILL REMAIN IN PLACE OVER THE FORECAST AREA TODAY...AND
WITH THE CLOUD COVER DON/T EXPECT HIGHS TO GET OUT OF THE TEENS.
TONIGHT AND FRIDAY...THE PRIMARY TROUGH WILL EXTEND FROM THE NORTHERN
PLANS THROUGH THE FOUR CORNERS. MEANWHILE...SEVERAL WEAK IMPULSES
OF SHORTWAVE ENERGY WILL QUICKLY PUSH SOUTH OUT OF CANADA INTO THE
CENTRAL PLAINS. THIS SHOULD KEEP AT LEAST SOME HIGH CLOUDS...BUT
MAY NOT BE TOO THICK. DID DROP LOWS ACROSS THE WESTERN PARTS OF
THE FORECAST AREA NEAR ZERO OR SLIGHTLY BELOW ZERO. IF CLOUDS
CLEAR...COULD CERTAINLY BE TOO WARM.
THE TROUGH DOES MOVE EAST INTO THE MISSISSIPPI RIVER VALLEY FRIDAY
NIGHT AND SATURDAY ALLOWING RIDGING TO START TO BUILD IN FOR THE
WEEKEND. THIS WILL BE THE START TO A SLOW WARMING TREND INTO NEXT
WEEK. NOT LOOKING FOR TEMPERATURES TO WARM DRAMATICALLY AS
SATURDAY HAS HIGHS NEAR THE FREEZING POINT. AREAS WITH SNOW COVER
WILL SEE A GREATER IMPACT IN TEMPERATURES SO IT IS LIKELY THAT
THERE WILL BE ADJUSTMENTS AFTER THE SNOW FIELD IS SAMPLED AFTER
TONIGHT.
.LONG TERM...SUNDAY THROUGH WEDNESDAY
THIS PERIOD BEGINS WITH RIDGING ACROSS THE PLAINS...HOWEVER THERE
IS GOOD CONSENSUS FROM THE MODEL OUTPUT BRINGING THE NEXT STRONG
TROUGH INTO THE WEST COAST ON SUNDAY. ALSO...SEVERAL STRONG
SHORTWAVE TROUGHS ARE BEING SHOWN IN THE NORTHERN STREAM WHICH
COULD COME SOUTH FAR ENOUGH TO KEEP THE RIDGE FROM BUILDING TOO
FAR NORTH. THIS WILL KEEP TEMPERATURES FROM MODERATING TOO MUCH
THROUGH THE FIRST PART OF NEXT WEEK. THE FIRST OF THESE SYSTEMS
COMES THROUGH SUNDAY NIGHT...WHICH SHOULDN/T HAVE ANY OTHER IMPACT
BUT TO BRING SOME COOLER AIR SOUTH INTO NEBRASKA. FOR MONDAY AND
BEYOND...THE MODELS BEGIN TO DIVERGE WITH THE EASTERN MOVEMENT OF
THE WEST COAST TROUGH. THE ECMWF IS SLOWER...WHICH THEN ALLOWS A
STRONG NORTHERN STREAM SYSTEM TO PENETRATE INTO NEBRASKA TUESDAY
NIGHT. THE GFS IS QUICKER AND KEEPS THIS SYSTEM UP OVER MINNESOTA
AND THE GREAT LAKES. EITHER WAY...MOISTURE LOOKS TO BE HELD TO THE
THE MAIN UPPER LOW WHICH STAYS WELL SOUTH SO NO FURTHER
PRECIPITATION CHANCES ARE IN THE FORECAST BEYOND FRIDAY MORNING.
&&
.AVIATION...
LIGHT SNOW IS EXPECTED TO CONTINUE NORTH AND WEST OF AN
ANW-TIF-MHN-OGA LINE THROUGH 21Z WITH THE HEAVIEST FROM 10-12Z.
CEILINGS BELOW 3000 FEET AGL ARE LIKELY WITH A FAIRLY STRONG
PROBABILITY OF 1000-2000 FEET AGL. IN ADDITION...WIDESPREAD
VISIBILITY BELOW 3SM IS LIKELY IN LIGHT SNOW UNTIL ABOUT 12Z WITH
LESS THAN 1SM POSSIBLE. LOW CEILING AND VISIBILITY MAY CONTINUE
UNTIL AT LEAST THIS EVENING 03Z...ESPECIALLY IN NORTH CENTRAL AND
NORTHWEST NEBRASKA.
&&
.HYDROLOGY...
ICE JAMS ARE LIKELY TO CONTINUE AT VARIOUS LOCATIONS IN CENTRAL
AND WESTERN NEBRASKA. EXCEPT FOR STRETCHES ALONG THE NORTH PLATTE
RIVER...THERE ARE NO INDICATIONS OF FLOODING. BE AWARE THAT THE
FORMATION AND BREAK-UP OF ICE JAMS ARE NOTORIOUSLY DIFFICULT TO
FORECAST...SO RIVERS AND STREAMS IN THE AREA MAY RISE AND FALL
ERRATICALLY. WE DO HAVE FAIRLY HIGH CONFIDENCE THAT...WITH
TEMPERATURES MODERATING SOME...THE LEVELS ARE NOT LIKELY TO HAVE
NEW SHARP RISES ABOVE CURRENT LEVELS.
THE NORTH PLATTE RIVER AT LEWELLEN CONTINUES TO FALL
SLOWLY...POSSIBLY BECAUSE THE RIVER HAS BECOME COMPLETELY FROZEN
AND THE ICE IS NO LONGER BEING CARRIED TOWARD THE INLET OF LAKE
MCCONAUGHY. AT THE NORTH PLATTE GAGE...THE LEVEL CONTINUES ABOVE
FLOOD STAGE AND IS LIKELY TO CONTINUE FOR AT LEAST THIS WEEKEND.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT/LONG TERM...BROOKS
AVIATION/HYDROLOGY...SPRINGER
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
302 AM CST THU DEC 27 2012
.DISCUSSION...
...SNOW AMOUNTS AND CHANCES FOR FREEZING DRIZZLE THE MAIN
CONCERNS...
FOR THIS FORECAST THE MAIN FEATURE OF INTEREST WILL BE THE POTENT
SHORTWAVE THAT IS CURRENTLY SPINNING ALONG THE WYOMING-COLORADO
BORDER PER WATER VAPOR LOOP AND THE PRECIPITATION IT WILL PRODUCE
TODAY AND FRIDAY. THE MORE THIS SYSTEM DEVELOPS THE MORE
IMPRESSIVE IT APPEARS TO BE...ESPECIALLY FOR NORTHEAST NEBRASKA.
500 MB HEIGHT FALLS ON THE 00Z RAOBS WERE 100-120 METERS IN THE
BASE OF THE TROF...WITH DENVER SHOWING A 130 METER FALL AT 300 MB.
150 KNOT JET STREAK WAS NOTED AT 25O MB OVER ARIZONA. REGIONAL
RADAR MOSAIC SHOWS SNOW RAPIDLY DEVELOPING/EXPANDING FROM WESTERN
KANSAS INTO WESTERN AND CENTRAL NEBRASKA IN RESPONSE TO THE
SYSTEMS VERTICAL MOTION AND MOISTURE AROUND 850 MB AS SEEN ON
DODGE CITY AND NORTH PLATTE SOUNDINGS. 08Z SURFACE ANALYSIS SHOWED
EARLY STAGES OF INVERTED TROF TAKING SHAPE WITH 1003MB PRESSURES
OBSERVED IN SOUTHEAST COLORADO.
THE DODGE CITY AND NORTH PLATTE SOUNDINGS DID HAVE A FEW DRY
LAYERS AS WELL...AND THESE DRY LAYERS DO COMPLICATE THE
PRECIPITATION FORECAST. GENERALLY THE NAM/GFS/RAP ARE IN DECENT
AGREEMENT ON THE PRECIPITATION FORECAST AND THE MOIST AND DRY
LAYERS. HOWEVER THERE IS CONCERN FOR A LIGHT FREEZING DRIZZLE
SCENARIO MAINLY IN THE SOUTHERN HALF OF THE FORECAST AREA DUE TO A
LOW LEVEL SATURATED LAYER THAT IS WARMER THAN -10C AND THEREFORE
WOULD PRIMARILY CONTAIN SUPERCOOLED DRIZZLE AS OPPOSED TO
SNOWFLAKES. THE MODELS SHOW LITTLE OR NO QPF OVER SOUTHEAST
NEBRASKA THROUGH 12Z FRIDAY...HOWEVER THE MODELS OFTEN POORLY HANDLE
THESE VERY LIGHT ICING EVENTS BECAUSE THE QPF IS QUITE LIGHT BUT
ALSO BECAUSE THE LAYERS ARE SHALLOW. THE FORECAST SOUNDINGS FROM
THE NAM AND ESPECIALLY THE RAP SUPPORT AT LEAST SOME LIGHT
FREEZING DRIZZLE MAINLY ALONG AND SOUTH OF INTERSTATE 80 AT
VARIOUS TIMES FROM LATE THIS AFTERNOON INTO TONIGHT...THEREFORE
WE HAVE ADDED PATCHY FREEZING DRIZZLE...OR AREAS OF FREEZING
DRIZZLE...TO THE SNOW CHANCES IN THOSE LOCATIONS. CONFIDENCE IN
THIS LIGHT ICING SCENARIO IS NOT HIGH ENOUGH TO ISSUE A WINTER
WEATHER ADVISORY FOR THE ABOVE MENTIONED AREAS. HOWEVER IF NEW
OBSERVATIONS AND MODEL RUNS SUGGEST A HIGHER LIKELIHOOD OF
FREEZING DRIZZLE AN ADVISORY MAY BE CONSIDERED LATER TODAY.
OTHERWISE THE TRACK OF THE LOW FAVORS THE HEAVIER SNOWS TO FALL IN
NORTHEAST NEBRASKA WHERE THE GOING WINTER WEATHER ADVISORY IS AT.
WE DID ADD ONE MORE TIER OF COUNTIES TO THE ADVISORY INCLUDING
ALBION AND NORFOLK. THIS SYSTEM IS UNIQUE IN THAT IT HAS A VERY
DEEP SATURATED LAYER THAT IS IN THE DENDRITIC GROWTH ZONE...AROUND
250 MB OR ABOUT 10000 FEET DEEP...YIELDING SNOW-LIQUID RATIOS AS
HIGH AS 20-1. BECAUSE OF THIS WE ALSO INCREASED SNOW AMOUNTS IN
NORTHEAST NEBRASKA ABOUT 1 MORE INCH. FORTUNATELY THERE WILL NOT
BE A LOT OF WIND WITH THIS SYSTEM SO LITTLE BLOWING AND DRIFTING
IS EXPECTED. SOME LOCATIONS IN THE ADVISORY AREA SHOULD SEE 4-5
INCHES OF DRY/FLUFFY SNOW STARTING TODAY AND ENDING FRIDAY
MORNING.
CONFIDENCE IN THE EXACT SNOW AMOUNTS IS MUCH LOWER TO THE SOUTH
OF THE ADVISORY AREA...MAINLY FROM THE LINCOLN TO OMAHA METRO
AREAS. HOWEVER...THERE IS LITTLE SUPPORT FOR MORE THAN 2 INCHES
GIVEN THE DRY LAYERS THAT WILL NEED TO BE SATURATED AND THE
WEAKER FORCING JUST SOUTH OF THE 700 MB LOW TRACK. CURRENTLY WE
ARE KEEPING THE 1-2 INCH AMOUNTS FOR LINCOLN-OMAHA AND THIS LOOKS
REASONABLE BY NOON FRIDAY WHEN ANY LIGHT SNOW ON THE BACK SIDE OF
THE LOW FINALLY ENDS. STARTED THE CHANCES FOR SNOW A BIT LATER
EAST OF A LINE FROM LINCOLN TO FREMONT...MAINLY CLOSER TO 18Z
TODAY...PRIMARILY DUE TO THE TIME IT WILL TAKE TO SATURATE THE
DRY LOW LEVELS IN THAT AREA.
TEMPERATURE AND WIND FORECASTS WERE ONLY SLIGHTLY ADJUSTED AS THE
PATTERN REMAINS FAIRLY COLD BUT DRY AFTER FRIDAY.
NIETFELD
&&
.AVIATION...
06Z TAFS FOR KOMA...KLNK AND KOFK.
DETERIORATING CONDITIONS ARE EXPECTED THROUGH THE 24 HOUR PERIOD
AT ALL TAF SITES. VFR CONDITIONS AT ALL TAF SITES INITIALLY WITH
LIGHT EAST SOUTHEAST WINDS. MID CLOUDS WILL INCREASE IN COVERAGE
AS A STORM SYSTEM BEGINS TO MOVE OFF THE HIGH PLAINS...BY 08-09Z
AT KOFK AND KLNK...AND KOMA BY 11Z. LIGHT SNOW AND MVFR CONDITIONS
WILL DEVELOP AT KOFK BY 13Z BECOMING PREVAILING BY 15Z WITH IFR
CONDITIONS DEVELOPING THEREAFTER. ONCE THE SNOW MOVES INTO THE
KOFK AREA...IT WILL LIKELY REMAIN THROUGH THE REST OF THE FORECAST
PERIOD WITH 2 TO 3 INCHES POSSIBLE THROUGH EARLY FRIDAY. AT
KOMA/KLNK...DRY AIR IN THE LOWER TO MID LEVELS SHOULD LIMIT
DEVELOPMENT EARLY IN THE TAF PERIOD...AND POSSIBLY DELAY ANY
FLURRY ACTIVITY UNTIL LATE AFTERNOON...OR MORE LIKELY UNTIL TOWARD
THE END OF THE PERIOD BY 28/02-06Z. COLD SEE MVFR FOG DEVELOP AT
KLNK/KOMA BY 15-19Z AS WELL.
DEWALD
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...WINTER WEATHER ADVISORY FROM NOON TODAY TO 6 AM CST FRIDAY FOR
NEZ011-012-015>018.
IA...WINTER WEATHER ADVISORY FROM NOON TODAY TO 6 AM CST FRIDAY FOR
IAZ043.
&&
$$
NIETFELD
AREA FORECAST DISCUSSION
NWS HASTINGS NE
243 AM CST THU DEC 27 2012
.SHORT TERM...THE MAIN ISSUE TO DEAL WITH IS TODAY/S LIGHT SNOW
EVENT.
WATER VAPOR AND INFRARED SATELLITE IMAGERY SUGGEST THE UPPER LEVEL
CIRCULATION SET TO IMPACT OUR AREA IS CENTERED IN THE TRI-STATE
CONFLUENCE OF WY/CO/NE. SPOKE OF ENERGY ALONG WITH WARM ADVECTION
PUSHING THROUGH THE FORECAST AT THIS TIME. RETURNS FROM NEARBY
RADARS SUGGEST PRECIPITATION IS DEVELOPING ALOFT IN THIS WARM
ADVECTION. NOTHING HAS REPORTEDLY MADE IT TO THE GROUND WITH DRY
AIR IN LOWER LEVELS OF THE ATMOSPHERE. THAT ALL SHOULD CHANGE
EARLY THIS MORNING...SAY AROUND DAWN...WITH LIGHT SNOWFALL STARTING
TO REACH THE SURFACE. SHORT TERM MODEL DATA /HRRR AND WRF/ POINT
TOWARD A BAND OF SNOW DEVELOPING IN THE VICINITY OF HIGHWAY 281
NAM QUICKLY LIFTING NORTH/NORTHEAST. THESE FINER DETAILS FIT WITH
THE NAM/GFS/SREF OUTPUT...WHICH EVENTUALLY PUT THE GREATEST
PRECIPITATION IN NORTHEAST NEBRASKA OF ABOUT 0.30". MEANWHILE...
THE NORTH/EAST FORECAST AREA MAY PICK UP A TENTH OR TWO OF LIQUID
EQUIVALENT MOISTURE...EQUATING INTO 1 TO 2 INCHES...MAYBE LOCALLY
3 INCHES OF SNOW. THE AREA AT MOST RISK FOR 3 INCHES...AND IT MAY
NOT BE THAT MUCH RISK...WOULD BE NORTHERN NANCE COUNTY...OR NORTHEAST
GREELEY COUNTY. THE VAST MAJORITY OF OUR NEBRASKA FORECAST IS IN
THE 1 TO 2 INCH RANGE...WITH LESS THAN 1 INCH IN NORTHERN KANSAS.
AT THIS TIME...WITH LIMITED WIND INFLUENCES...AND ONLY A SMALL PART
OF THE FORECAST AREA IN LINE FOR MARGINAL ADVISORY LEVEL SNOW
AMOUNTS...WILL NOT ISSUE ANY HEADLINES. IN FACT...IF YOU BUY INTO
THE 05Z HRRR OUTPUT...ONLY THE FAR NORTHEAST FORECAST AREA WOULD
CATCH 1 TO 2 INCHES OF SNOW...AND THE REST OF THE AREA AN INCH OR
LESS. AT THIS POINT...THERE SEEMS TO BE ENOUGH REASON NOT TO ISSUE
ANY ADVISORIES FOR THIS EVENT.
SHOULD MENTION...NAM SOUNDINGS IN THE SOUTHEAST PART OF THE FORECAST
AREA...ALONG WITH FUZZY NATURE OF PRECIPITATION OUTLOOK...SUGGEST A
BIT OF FREEZING DRIZZLE COULD DEVELOP DURING THE EVENING HOURS. LIFT
IS THE QUESTION...MEANING IS THERE ENOUGH? THINK THERE COULD BE A
COUPLE OF HOURS OF FREEZING DRIZZLE TYPE PRECIPITATION IN THIS AREA
AND HAVE ADDED THAT TO THE FORECAST GRIDS. NOT A HUGE DEAL...AND MAY
NOT MATERIALIZE...BUT WOULDN/T BE SHOCKED IF IT DID PAN OUT.
ON FRIDAY...THE MEANDERING NATURE OF THE UPPER LEVEL LOW TO THE
SOUTHEAST WILL KEEP CLOUDS AROUND FOR A GOOD PART OF THE DAY. FAR
EASTERN FORECAST AREA MAY EVEN SEE A LINGERING FLURRY EARLY IN THE
MORNING. ASIDE FROM THAT...NORTHWEST WINDS WILL DEVELOP...AND MAY
EVEN TURN SNEAKY BREEZY IF CLEARING DEVELOPS MORE RAPIDLY. FRIDAY
IS STILL A PART OF THE CURRENT COLD SPELL WITH HIGHS STRUGGLING FOR
ABOUT 20 MOST AREAS. THAT ALL STARTS TO CHANGE FRIDAY NIGHT...AS
DOWN-SLOPING WESTERLY WINDS SET UP AND LASTS INTO THE DAY SATURDAY.
THIS WILL RESULT IN SATURDAY BEING MUCH WARMER...RELATIVE TO RECENT
DAYS...WITH HIGHS IN THE UPPER 20S AND LOWER 30S AND PLENTY OF
SUNSHINE. THAT WON/T NECESSARILY MELT A WHOLE LOT...AND ITS STILL
BELOW NORMAL SOME 5 TO 7 DEGREES...BUT ITS AT LEAST A START.
.LONG TERM...STARTING SUNDAY MORNING...SUNDAY IS SHAPING UP TO BE
THE WARMEST DAY IN JUST OVER A WEEK AS THE COMBINATION OF WARMER AIR
SURGING NORTHWARD AHEAD OF AN APPROACHING LOW LEVEL TROUGH/FRONT AND
MOSTLY SUNNY SKIES UNDER THE INFLUENCE OF A BUILDING UPPER LEVEL
RIDGE...WILL RESULT IN A RETURN TO NEAR SEASONAL TEMPERATURES FOR
THE END OF DECEMBER. AS A RESULT...EXPECT TO SEE AFTERNOON
TEMPERATURES ACROSS SOUTH CENTRAL NEBRASKA APPROACH THE FREEZING
MARK...WITH UPPER 30S TO NEAR 40 DEGREES CURRENTLY FORECAST FOR
PORTIONS OF NORTH CENTRAL KANSAS. WHILE THIS LIKELY WILL NOT BE WARM
ENOUGH TO RESULT IN ANY SIGNIFICANT MELTING OF SNOW/ICE ON THE
GROUND...IT WILL LIKELY BE THE FIRST DAY SINCE DECEMBER 22ND THAT
TEMPERATURES WILL CLIMB ABOVE THE FREEZING MARK ACROSS THE MAJORITY
OF THE FORECAST AREA. THIS BRIEF WARM UP...HOWEVER...IS EXPECTED TO
BE FAIRLY SHORT LIVED...AS GLOBAL MODELS ARE INDICATING COOLER AIR
BEHIND THE APPROACHING TROUGH/FRONT...WHICH WILL BEGIN TO FILTER IN
ACROSS THE LOCAL AREA TO START THE NEW WORK WEEK. AS A
RESULT...EXPECT A RETURN TO SUBFREEZING AFTERNOON TEMPERATURES
MONDAY AFTERNOON WITH LITTLE EVIDENCE FOR ENOUGH LOW LEVEL MOISTURE
OR FORCING TO JUSTIFY ANYTHING OTHER THAN AN INCREASE IN CLOUDS
ACROSS THE LOCAL AREA MONDAY.
THEREAFTER...THE GLOBAL MODELS BEGIN TO DIVERGE SOME WITH THEIR
HANDLING OF AN UPPER LEVEL LOW ACROSS THE DESERT SOUTHWEST...WITH
THE GFS MAINTAINING A MUCH MORE PROGRESSIVE FLOW PATTERN THAN THE
EC...WHICH HAS BEEN TRYING TO CUT OFF THE UPPER LEVEL LOW ACROSS
NORTHERN MEXICO. HOWEVER...IN BOTH SCENARIOS...THE NORTHERN JET IS
FORECAST TO STEER AN UPPER LEVEL DISTURBANCE ACROSS NEBRASKA TUESDAY
NIGHT/WEDNESDAY...WHICH ONCE AGAIN IS EXPECTED TO HAVE A LACK IN
APPRECIABLE LOW LEVEL MOISTURE...WITH LITTLE MORE THAN A FEW HIGH
CLOUDS AND A CONTINUATION OF SUB FREEZING TEMPERATURES EXPECTED TO
PERSIST AS A RESULT. JUST BEYOND THE CURRENT SCOPE OF THE
FORECAST...THERE ARE SOME INDICATIONS THAT ANOTHER UPPER LEVEL RIDGE
OF HIGH PRESSURE WILL BUILD ACROSS THE CENTRAL PLAINS IN CONCERT
WITH A MORE SIGNIFICANT DOWN-SLOPING LOW LEVEL FLOW...WHICH MAY
RESULT IN TEMPERATURES WARMING ABOVE CLIMO TOWARDS THE END OF NEXT
WEEK.
&&
.PREV DISCUSSION... /ISSUED 1050 PM CST WED DEC 26 2012/
AVIATION...06Z KGRI TAF. VFR CONDITIONS EXPECTED THROUGH
11Z...WITH DETERIORATING CONDITIONS THEREAFTER. THE APPROACH OF A
STORM SYSTEM WILL BRING LOWERING CEILINGS AND SNOW TO THE AREA
DURING THE DAY THURSDAY. MVFR CONDITIONS ARE CURRENTLY EXPECTED
11-14Z...WITH IFR CONDITIONS 14-22Z. MVFR CONDITIONS ARE THEN
FORECAST 22Z ONWARD. THE SURFACE WIND WILL REMAIN FROM THE
EAST/SOUTHEAST AT AROUND 11KTS THROUGH MUCH OF THE TAF PERIOD.
VISIBILITY RESTRICTIONS WILL ALSO BE POSSIBLE IN -SN DURING THE
TAF PERIOD.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
AVIATION...SAR
SHORT TERM...NOAA/NWS/MORITZ
LONG TERM...SAR
$$
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
318 AM EST THU DEC 27 2012
.SYNOPSIS...
A POTENT WINTER STORM WILL IMPACT THE ENTIRE REGION TONIGHT
THROUGH THURSDAY NIGHT PRODUCING WIDESPREAD HEAVY SNOWS WITH
AMOUNTS OVER A FOOT. GUSTY WINDS WILL ALSO OCCUR ALONG THE WESTERN
SLOPES OF THE GREEN MOUNTAINS AND IN THE SAINT LAWRENCE VALLEY,
AND THIS MAY CAUSE AREAS OF BLOWING SNOW. SNOW SHOWERS WILL
CONTINUE ACROSS THE NORTHERN MOUNTAINS ON FRIDAY AS THE STORM
MOVES AWAY FROM THE REGION. THE WEEKEND WILL BE SEASONABLY COLD,
WITH A CONTINUED CHANCE OF LIGHT SNOW IN THE MOUNTAINS.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
AS OF 1227 AM EST THURSDAY...EVERYTHING STILL ON TRACK WITH ONLY
MINOR ADJUSTMENTS MADE TO GOING FORECAST. LOW PRESSURE IS LOCATED
NEAR TIP OF SOUTHERN NEW JERSEY AT 992 MB. GREATEST PRESSURE FALLS
ARE ALONG THE NEW JERSEY COASTLINE...CONTINUING TO SUGGEST A TRACK
TOWARDS LONG ISLAND OVERNIGHT. SNOW HAS MADE IT AS FAR NORTH AS
BURLINGTON AND MASSENA AND WILL OVERSPREAD REST OF NORTHERN
VERMONT OVER NEXT COUPLE OF HOURS. INTENSITY OF SNOW INCREASES
QUICKLY AFTER ONSET. HAVE SEEN WIDESPREAD 1-2" PER HOUR RATES
ACROSS NEW YORK AND SOUTHERN VERMONT AS WELL AS POINTS FURTHER
SOUTH. LATEST HRRR CONTINUES TO SHOW THIS HEAVY BAND MOVING
NORTHWARD...WITH HEAVIEST PRECIP THROUGH 8Z IN SOUTHERN
AREAS...5-10Z IN THE CHAMPLAIN VALLEY AND NORTHERN VERMONT...AND
7-13Z ACROSS NORTHERN NEW YORK. ALSO OF NOTE...DOWNSLOPE WINDS
GUSTING INTO THE 20S ACROSS SOUTHWEST VERMONT.
EARLIER DISCUSSION FROM 642 PM EST...
EVERYTHING REMAINS ON TRACK...AND ONLY MINOR ADJUSTMENTS WERE
MADE. HAD TO DROP TEMPERATURES SLIGHTLY THIS EVENING...WITH
WIDESPREAD TEENS ACROSS THE REGION. LOWS WILL BE REACHED OVER THE
NEXT COUPLE OF HOURS...AND THEN SLOWLY RISE OVERNIGHT.
OTHERWISE...TRIED TO NARROW DOWN THE START TIME FOR SNOW ACROSS
THE AREA. PRIMARY LOW NOW LOCATED OVER WEST VIRGINIA WITH A
SECONDARY LOW DEVELOPING NEAR WAKEFIELD VIRGINIA. SECONDARY LOW
WILL TAKE OVER DURING THE REST OF THE EVENING AND PROGRESS TO NEAR
DELAWARE BY 03Z...NEW YORK CITY BY 09Z....AND THEN LONG ISLAND BY
12Z. JUDGING BY CURRENT OBSERVATIONS...SNOW HAS NOW REACHED AS FAR
NORTH AS THE MID-HUDSON VALLEY...THE CENTRAL MOHAWK VALLEY...AND
THE SHORES OF LAKE ONTARIO IN NEW YORK...WITH A SLOW NORTHWARD
PROGRESSION. SHOULD BE INTO THE ADIRONDACKS AND SOUTHERN VERMONT
AROUND 02Z (9 PM)...THE CHAMPLAIN VALLEY AROUND 04Z (11 PM)...AND
THE NORTHEAST KINGDOM AROUND 05Z (MIDNIGHT). HEAVIEST SNOW WITH
INITIAL BAND OF WARM AIR ADVECTION PRECIPITATION WILL LIKELY OCCUR
BETWEEN 07Z AND 10Z (2 AM AND 5 AM) WHERE RATES OF 1-2 INCHES PER
HOUR ARE POSSIBLE...ESPECIALLY IN THE SOUTHEAST- UPSLOPE FAVORED
LOCATIONS. DOWNSLOPE WINDS WILL ALSO BE INCREASING ACROSS THE
SOUTHERN GREENS WITH GUSTS UP TO 40 MPH POSSIBLE IN EASTERN
ADDISON AND RUTLAND COUNTIES BETWEEN 06Z AND 10Z (1 AM AND 5 AM).
THIS WILL CREATE SOME WARMING AND DRYING IN THOSE AREAS...AND
COMBINED WITH SOME WARMING ALOFT (750-800 MB) AS INDICATED BY
LATEST RAP AND NAM...WILL LIKELY SEE SOME SLEET MIX IN ACROSS
RUTLAND AND WINDSOR COUNTIES AFTER 07Z...AND ESPECIALLY AFTER 10Z.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH SATURDAY/...
AS OF 325 PM EST WEDNESDAY...GONNA BE A BUSY DAY THURSDAY. LOTS OF
SNOW. THE STORM WILL TRACK NORTHEAST AND CUT ACROSS CAPE COD (OR
VERY NEAR IT) BY LATE IN THE AFTERNOON. THIS PUTS THE NORTH
COUNTRY INTO A SWEET SPOT FOR THE HEAVIEST QPF. THE DRY SLOT JUST
WONT GET THIS FAR NORTH, AND AS THE LOW MOVES OFF TO THE EAST,
WE`LL BE IN THE PIVOT ZONE INTO THE AFTERNOON.
EXCELLENT DYNAMICS AND SNOW GROWTH MAXED WITH UPWARD MOTION
SHOULD RESULT IN A PERIOD OF HEAVY SNOW MOST EVERYWHERE. THINKING
THE PRIMARY TIME WILL BE 6AM TO NOON, WITH RATES OF 1-2" PER HOUR.
CAN`T RULE OUT LOCALIZED MESOSCALE BAND WITH EVEN A LITTLE BIT
MORE. LIQUID QPF WILL BE QUITE IMPRESSIVE. SPENT A GOOD DEAL OF
TIME TRYING TO ACCOUNT FOR OROGRAPHIC EFFECTS AS WELL. BY THE TIME
WE GET TO THURSDAY NIGHT, MOST OF US WILL SEE ON THE ORDER OF 1 TO
1.5" OF LIQUID EQUIVALENT. SHADOWING WILL MAKE THE NUMBER A LITTLE
LOWER IN THE NORTHEAST KINGDOM AND WESTERN SLOPES OF THE SOUTHERN
GREENS, BUT THEN THAT ON THE FLIP SIDE, OROGRAPHICS WILL HELP ON
THE EASTERN SIDES OF THE GREENS AND DACKS. HAVE INCREASED THE SNOW
TOTALS A FEW INCHES ACROSS THE BOARD -- THINKING 12 TO 17 INCHES,
WITH THE JACKPOT LOCATIONS SEEING ABOUT 20". EVEN THOSE WHO SEE
THE LEAST WILL GET ABOUT 8", WHICH IS NOT SHABBY.
WINDS WILL CONTINUE TO BE GUSTY THE FIRST HALF OF THURSDAY ALONG
THE WESTERN SLOPES. ALSO HAVE TO WATCH FOR STRONG NORTHEAST WINDS
FUNNELING DOWN THE ST LAWRENCE VALLEY. DONT THINK THEY`LL HIT
WIND ADVISORY CRITERIA, BUT STILL THEY`LL HAVE SUSTAINED WINDS 15
TO 25 MPH WITH HIGHER GUSTS -- AND THAT WILL CAUSE A CONSIDERABLE
AMOUNT OF DRIFTING/BLOWING SNOW OUT THERE. HAVE ADDED THAT WORDING
TO THE FORECAST.
SNOW WILL BEGIN TO TAPER OFF IN THE EVENING, THOUGH LIGHT SNOWS
WILL CONTINUE ALL NIGHT. AS THE LOW PUSHES EAST OF HERE, WINDS
WILL CLOCK AROUND TO NORTHWEST. MOISTURE WILL BE SLOW TO LEAVE, SO
THE NORTHWEST WINDS AND THAT MOISTURE WILL RESULT IN A GOOD AMOUNT
OF OROGRAPHICS, SO THE HIGHER TERRAIN WILL PICK UP A FEW
ADDITIONAL INCHES OF SNOW (AT LEAST) ON FRIDAY.
FINALLY TAPER POPS DOWN TO CHANCE LEVELS BY FRIDAY NIGHT, THOUGH A
WEAK SYSTEM APPROACHING FROM THE WEST MAY SPARK A LITTLE BIT OF
LIGHT SNOW/FLURRIES.
QUICK NOTE ON TEMPERATURES -- PRIMARILY KEPT TO THE COOLER SIDE OF
GUIDANCE FOR THE ENTIRE TIME.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 317 AM EST THURSDAY...LITTLE OVERALL CHANGE IN PREVIOUS DAYS
FORECAST THINKING FOR THE LONG TERM FORECAST AS MEDIUM RANGE
MODELS REMAIN CONSISTENT WITH THEIR RESPECTIVE SOLUTIONS...ALBEIT
WITH A FEW MINOR DIFFERENCES.
LOW PRESSURE DEVELOPING OFF THE CAROLINA/VIRGINIA COASTLINE LATE
SATURDAY AFTERNOON STILL ON TRACK TO MOVE NORTHEAST JUST OUTSIDE THE
BENCHMARK SATURDAY NIGHT INTO SUNDAY MORNING. LATEST TRENDS OF THE
GFS/ECMWF HAVE THE LOW TRACK EVER SO SLIGHTLY WEST COMPARED TO
PREVIOUS RUNS...WHICH BRINGS A LITTLE MORE LIGHT SNOW TO THE NORTH
COUNTRY...THOUGH REALLY NOTHING TO GET TOO WORKED UP ABOUT. WILL
CONTINUE TO PLAY SOME MIDDLE OF THE ROAD POPS (30-50%) ACROSS MAINLY
CENTRAL AND SOUTHERN PORTIONS OF THE AREA SATURDAY NIGHT AND SUNDAY
MORNING...WITH THE POSSIBILITY OF A COUPLE OF INCHES OF SNOW.
BRIEF RIDGE OF HIGH PRESSURE BUILDS IN FOR LATE SUNDAY NIGHT INTO
MONDAY WITH GENERALLY DRY CONDITIONS EXPECTED...ALBEIT CLOUDY AS
UPPER FLOW REMAINS FAIRLY ZONAL. MONDAY NIGHT INTO TUESDAY MORNING A
WEAK CLIPPER WILL BRING THE POSSIBILITY OF A FEW LIGHT SNOW SHOWERS
TO MAINLY NORTHERN SECTIONS OF THE CWA...FOLLOWED BY A WELL DEFINED
ARCTIC AIRMASS/BOUNDARY WHICH LOOKS TO AFFECT THE REGION THROUGH THE
REMAINDER OF THE FORECAST PERIOD. SOME DIFFERENCES STILL EXIST
BETWEEN THE GFS AND ECMWF IN REGARDS TO THE STRENGTH OF THIS
AIRMASS...WITH THE ECMWF ON THE COLDER SIDE OF NWP GUIDANCE. AS I
DID YESTERDAY...HAVE GONE WITH A BLEND FOR NOW WITH THE MAIN
HIGHLIGHTS FOR THE MIDDLE OF NEXT WEEK BEING BELOW NORMAL TEMPS AND
LOW CHANCES FOR A FEW LIGHT SNOW SHOWERS.
&&
.AVIATION /08Z THURSDAY THROUGH MONDAY/...
THROUGH 06Z FRIDAY...IFR TO VLIFR CONDITIONS IN HEAVY SNOW WILL
CONTINUE THROUGH THE MAJORITY OF THE TAF PERIOD AT ALL SITES. MAY
SEE A BRIEF PERIOD OF SLEET AT KRUT IN THE PRE-DAWN HOURS DUE TO
DOWNSLOPING WINDS AND WARMING ALOFT. IN ADDITION TO LOW FLIGHT
CATEGORIES...WINDS WILL BE AN ISSUE AT VARYING TIMES THROUGH THE
PERIOD. EAST TO SOUTHEAST LOW LEVEL JET MOVES ACROSS THE REGION
OVERNIGHT...WITH KRUT LIKELY TO EXPERIENCE STRONGEST WIND GUSTS
20-35 KTS THROUGH 12Z. ALSO...VALLEY CHANNELING AT KMSS WILL
PRODUCE GUSTS TO 20-25 KTS THROUGH THE PERIOD. ELSEWHERE STRONG
WINDS ARE LESS FAVORABLE...BUT SHOULD STILL TO SEE GUSTS TO 15-20
KTS MAINLY AFTER 12Z. THIS WILL CREATE AREAS OF BLOWING SNOW AND
NEAR WHITE-OUT CONDITIONS.
OUTLOOK 06Z FRIDAY THROUGH MONDAY...
06Z FRIDAY THROUGH 00Z SATURDAY...MVFR/IFR CONDITIONS TRENDING TO
VFR IN THE VALLEYS AS LOW PRESSURE MOVES INTO THE GULF OF MAINE.
IN ADDITION...FRESH SNOW AND GUSTY WINDS WILL PRODUCE SOME AREAS
OF BLOWING/DRIFTING SNOW.
00Z SATURDAY THROUGH 00Z SUNDAY...MAINLY VFR CONDITIONS AS HIGH
PRESSURE BUILDS INTO THE REGION. LINGERING MVFR SNOW SHOWERS
POSSIBLE AT MPV/SLK THRU 06Z SATURDAY.
00Z SUNDAY THROUGH MONDAY...MAINLY VFR CONDITIONS WITH A CHANCE OF
MVFR SNOW SHOWERS ACROSS CENTRAL AND SOUTHERN AREAS SATURDAY NIGHT
AS LOW PRESSURE PASSES SOUTH AND EAST OF THE REGION.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...WINTER STORM WARNING UNTIL 7 AM EST FRIDAY FOR VTZ001>012-
016>019.
NY...WINTER STORM WARNING UNTIL 7 AM EST FRIDAY FOR NYZ026>031-034-
035-087.
&&
$$
SYNOPSIS...NASH
NEAR TERM...RJS/MUCCILLI
SHORT TERM...NASH
LONG TERM...LAHIFF
AVIATION...LAHIFF
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
1254 AM EST THU DEC 27 2012
.SYNOPSIS...
A POTENT WINTER STORM WILL IMPACT THE ENTIRE REGION TONIGHT
THROUGH THURSDAY NIGHT PRODUCING WIDESPREAD HEAVY SNOWS WITH
AMOUNTS OVER A FOOT. GUSTY WINDS WILL ALSO OCCUR ALONG THE WESTERN
SLOPES OF THE GREEN MOUNTAINS AND IN THE SAINT LAWRENCE VALLEY,
AND THIS MAY CAUSE AREAS OF BLOWING SNOW. SNOW SHOWERS WILL
CONTINUE ACROSS THE NORTHERN MOUNTAINS ON FRIDAY AS THE STORM
MOVES AWAY FROM THE REGION. THE WEEKEND WILL BE SEASONABLY COLD,
WITH A CONTINUED CHANCE OF LIGHT SNOW IN THE MOUNTAINS.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
AS OF 1227 AM EST THURSDAY...EVERYTHING STILL ON TRACK WITH ONLY
MINOR ADJUSTMENTS MADE TO GOING FORECAST. LOW PRESSURE IS LOCATED
NEAR TIP OF SOUTHERN NEW JERSEY AT 992 MB. GREATEST PRESSURE FALLS
ARE ALONG THE NEW JERSEY COASTLINE...CONTINUING TO SUGGEST A TRACK
TOWARDS LONG ISLAND OVERNIGHT. SNOW HAS MADE IT AS FAR NORTH AS
BURLINGTON AND MASSENA AND WILL OVERSPREAD REST OF NORTHERN
VERMONT OVER NEXT COUPLE OF HOURS. INTENSITY OF SNOW INCREASES
QUICKLY AFTER ONSET. HAVE SEEN WIDESPREAD 1-2" PER HOUR RATES
ACROSS NEW YORK AND SOUTHERN VERMONT AS WELL AS POINTS FURTHER
SOUTH. LATEST HRRR CONTINUES TO SHOW THIS HEAVY BAND MOVING
NORTHWARD...WITH HEAVIEST PRECIP THROUGH 8Z IN SOUTHERN
AREAS...5-10Z IN THE CHAMPLAIN VALLEY AND NORTHERN VERMONT...AND
7-13Z ACROSS NORTHERN NEW YORK. ALSO OF NOTE...DOWNSLOPE WINDS
GUSTING INTO THE 20S ACROSS SOUTHWEST VERMONT.
EARLIER DISCUSSION FROM 642 PM EST...
EVERYTHING REMAINS ON TRACK...AND ONLY MINOR ADJUSTMENTS WERE
MADE. HAD TO DROP TEMPERATURES SLIGHTLY THIS EVENING...WITH
WIDESPREAD TEENS ACROSS THE REGION. LOWS WILL BE REACHED OVER THE
NEXT COUPLE OF HOURS...AND THEN SLOWLY RISE OVERNIGHT.
OTHERWISE...TRIED TO NARROW DOWN THE START TIME FOR SNOW ACROSS
THE AREA. PRIMARY LOW NOW LOCATED OVER WEST VIRGINIA WITH A
SECONDARY LOW DEVELOPING NEAR WAKEFIELD VIRGINIA. SECONDARY LOW
WILL TAKE OVER DURING THE REST OF THE EVENING AND PROGRESS TO NEAR
DELAWARE BY 03Z...NEW YORK CITY BY 09Z....AND THEN LONG ISLAND BY
12Z. JUDGING BY CURRENT OBSERVATIONS...SNOW HAS NOW REACHED AS FAR
NORTH AS THE MID-HUDSON VALLEY...THE CENTRAL MOHAWK VALLEY...AND
THE SHORES OF LAKE ONTARIO IN NEW YORK...WITH A SLOW NORTHWARD
PROGRESSION. SHOULD BE INTO THE ADIRONDACKS AND SOUTHERN VERMONT
AROUND 02Z (9 PM)...THE CHAMPLAIN VALLEY AROUND 04Z (11 PM)...AND
THE NORTHEAST KINGDOM AROUND 05Z (MIDNIGHT). HEAVIEST SNOW WITH
INITIAL BAND OF WARM AIR ADVECTION PRECIPITATION WILL LIKELY OCCUR
BETWEEN 07Z AND 10Z (2 AM AND 5 AM) WHERE RATES OF 1-2 INCHES PER
HOUR ARE POSSIBLE...ESPECIALLY IN THE SOUTHEAST- UPSLOPE FAVORED
LOCATIONS. DOWNSLOPE WINDS WILL ALSO BE INCREASING ACROSS THE
SOUTHERN GREENS WITH GUSTS UP TO 40 MPH POSSIBLE IN EASTERN
ADDISON AND RUTLAND COUNTIES BETWEEN 06Z AND 10Z (1 AM AND 5 AM).
THIS WILL CREATE SOME WARMING AND DRYING IN THOSE AREAS...AND
COMBINED WITH SOME WARMING ALOFT (750-800 MB) AS INDICATED BY
LATEST RAP AND NAM...WILL LIKELY SEE SOME SLEET MIX IN ACROSS
RUTLAND AND WINDSOR COUNTIES AFTER 07Z...AND ESPECIALLY AFTER 10Z.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH FRIDAY NIGHT/...
AS OF 325 PM EST WEDNESDAY...GONNA BE A BUSY DAY THURSDAY. LOTS OF
SNOW. THE STORM WILL TRACK NORTHEAST AND CUT ACROSS CAPE COD (OR
VERY NEAR IT) BY LATE IN THE AFTERNOON. THIS PUTS THE NORTH
COUNTRY INTO A SWEET SPOT FOR THE HEAVIEST QPF. THE DRY SLOT JUST
WONT GET THIS FAR NORTH, AND AS THE LOW MOVES OFF TO THE EAST,
WE`LL BE IN THE PIVOT ZONE INTO THE AFTERNOON.
EXCELLENT DYNAMICS AND SNOW GROWTH MAXED WITH UPWARD MOTION
SHOULD RESULT IN A PERIOD OF HEAVY SNOW MOST EVERYWHERE. THINKING
THE PRIMARY TIME WILL BE 6AM TO NOON, WITH RATES OF 1-2" PER HOUR.
CAN`T RULE OUT LOCALIZED MESOSCALE BAND WITH EVEN A LITTLE BIT
MORE. LIQUID QPF WILL BE QUITE IMPRESSIVE. SPENT A GOOD DEAL OF
TIME TRYING TO ACCOUNT FOR OROGRAPHIC EFFECTS AS WELL. BY THE TIME
WE GET TO THURSDAY NIGHT, MOST OF US WILL SEE ON THE ORDER OF 1 TO
1.5" OF LIQUID EQUIVALENT. SHADOWING WILL MAKE THE NUMBER A LITTLE
LOWER IN THE NORTHEAST KINGDOM AND WESTERN SLOPES OF THE SOUTHERN
GREENS, BUT THEN THAT ON THE FLIP SIDE, OROGRAPHICS WILL HELP ON
THE EASTERN SIDES OF THE GREENS AND DACKS. HAVE INCREASED THE SNOW
TOTALS A FEW INCHES ACROSS THE BOARD -- THINKING 12 TO 17 INCHES,
WITH THE JACKPOT LOCATIONS SEEING ABOUT 20". EVEN THOSE WHO SEE
THE LEAST WILL GET ABOUT 8", WHICH IS NOT SHABBY.
WINDS WILL CONTINUE TO BE GUSTY THE FIRST HALF OF THURSDAY ALONG
THE WESTERN SLOPES. ALSO HAVE TO WATCH FOR STRONG NORTHEAST WINDS
FUNNELING DOWN THE ST LAWRENCE VALLEY. DONT THINK THEY`LL HIT
WIND ADVISORY CRITERIA, BUT STILL THEY`LL HAVE SUSTAINED WINDS 15
TO 25 MPH WITH HIGHER GUSTS -- AND THAT WILL CAUSE A CONSIDERABLE
AMOUNT OF DRIFTING/BLOWING SNOW OUT THERE. HAVE ADDED THAT WORDING
TO THE FORECAST.
SNOW WILL BEGIN TO TAPER OFF IN THE EVENING, THOUGH LIGHT SNOWS
WILL CONTINUE ALL NIGHT. AS THE LOW PUSHES EAST OF HERE, WINDS
WILL CLOCK AROUND TO NORTHWEST. MOISTURE WILL BE SLOW TO LEAVE, SO
THE NORTHWEST WINDS AND THAT MOISTURE WILL RESULT IN A GOOD AMOUNT
OF OROGRAPHICS, SO THE HIGHER TERRAIN WILL PICK UP A FEW
ADDITIONAL INCHES OF SNOW (AT LEAST) ON FRIDAY.
FINALLY TAPER POPS DOWN TO CHANCE LEVELS BY FRIDAY NIGHT, THOUGH A
WEAK SYSTEM APPROACHING FROM THE WEST MAY SPARK A LITTLE BIT OF
LIGHT SNOW/FLURRIES.
QUICK NOTE ON TEMPERATURES -- PRIMARILY KEPT TO THE COOLER SIDE OF
GUIDANCE FOR THE ENTIRE TIME.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AS OF 342 PM EST WEDNESDAY...OVERALL LITTLE CHANGE FROM PREVIOUS
COUPLE OF FCSTS...WITH BLW NORMAL TEMPS AND PRECIP EXPECTED FOR
DAYS 4 THRU 7. THE EXTENDED FCST CHALLENGE WL BE TIMING/MAGNITUDE
OF ARCTIC AIRMASS ACRS OUR CWA EARLY NEXT WK. WL CONT TO MENTION
LOW CHC POPS FOR LATE SAT INTO SUNDAY ASSOCIATED WITH MID/UPPER
LVL TROF AND SOME 850 TO 500MB RH. LATEST TRENDS HAVE BEEN FOR
LESS RH AND QPF ACRS OUR CWA...BUT ECMWF IS A BIT CLOSER TO THE
COAST WITH SFC LOW PRES AND ENOUGH MOISTURE MAY MOVE BACK INTO OUR
CWA FOR SOME LIGHT SNOW. OTHERWISE...ECMWF/GEM SHOW MID/UPPER LVL
TROF DEVELOPING ACRS EASTERN CANADA WITH A MAINLY DRY NW FLW
ALOFT. HOWEVER...A WELL DEFINED ARCTIC BOUNDARY WL PUSH ACRS OUR
CWA EARLY NEXT WEEK...ALONG WITH A RIBBON OF ENHANCED MOISTURE.
THIS MOISTURE...ALONG WITH SOME ADDITIONAL MOISTURE FROM THE GREAT
LAKES WL HELP IN PRODUCING SOME SNOW SHOWERS ACRS OUR CWA ON
MONDAY INTO TUES. IN ADDITION...MUCH COLDER TEMPS WL ADVECT BACK
INTO OUR CWA FOR NEXT WK. STILL SOME UNCERTAINTY WITH REGARDS TO
TIMING OF THIS FEATURE...AS GFS IS 6 TO 12 HRS SLOWER AND SHOWS
THE COLDEST TEMPS ACRS OUR CWA ON WEDS. TIMING OF BOUNDARY WL MAKE
A HUGE DIFFERENCE IN TEMPS FROM NEAR 30F AT BTV IF THE GFS IS
RIGHT TO LOWER TEENS IF THE ECMWF/GEM ARE CORRECT ON TUES. GIVEN THE
DEVELOPMENT OF A LARGE SCALE TROF AND DEEP CYCLONIC FLW ACRS THE
NE CONUS...WL TREND TWD THE COLDER ECMWF/GEM FOR NEXT WEEK...AND
MENTION HIGHS ONLY IN THE TEENS/L20S WITH LOWS MAINLY IN THE
SINGLE DIGITS/LOWER TEENS. IF SFC HIGH PRES BUILDS INTO THE
REGION...FASTER THAN PROGGED...THEN WINDS WL DECREASE AND
OVERNIGHT LOWS WL NEED TO BE ADJUSTED DOWN BY 5 TO 10 DEGREES. ITS
ALWAYS DIFFICULT TO DETERMINE AMOUNT OF CAA AND IMPACTS ACRS OUR
CWA IN THE DAY 5 TO 7 RANGE. TODAY IS A GREAT EXAMPLE OF TRYING TO
PREDICT THE COLD AIR...AS TEMPS STRUGGLED MAINLY IN THE TEENS.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
THROUGH 06Z FRIDAY...IFR TO VLIFR CONDITIONS IN HEAVY SNOW WILL
CONTINUE THROUGH THE MAJORITY OF THE TAF PERIOD AT ALL SITES. MAY
SEE A BRIEF PERIOD OF SLEET AT KRUT IN THE PRE-DAWN HOURS DUE TO
DOWNSLOPING WINDS AND WARMING ALOFT. IN ADDITION TO LOW FLIGHT
CATEGORIES...WINDS WILL BE AN ISSUE AT VARYING TIMES THROUGH THE
PERIOD. EAST TO SOUTHEAST LOW LEVEL JET MOVES ACROSS THE REGION
OVERNIGHT...WITH KRUT LIKELY TO EXPERIENCE STRONGEST WIND GUSTS
20-35 KTS THROUGH 12Z. ALSO...VALLEY CHANNELING AT KMSS WILL
PRODUCE GUSTS TO 20-25 KTS THROUGH THE PERIOD. ELSEWHERE STRONG
WINDS ARE LESS FAVORABLE...BUT SHOULD STILL TO SEE GUSTS TO 15-20
KTS MAINLY AFTER 12Z. THIS WILL CREATE AREAS OF BLOWING SNOW AND
NEAR WHITE-OUT CONDITIONS.
OUTLOOK 06Z FRIDAY THROUGH MONDAY...
06Z FRIDAY THROUGH 00Z SATURDAY...MVFR/IFR CONDITIONS TRENDING TO
VFR IN THE VALLEYS AS LOW PRESSURE MOVES INTO THE GULF OF MAINE.
IN ADDITION...FRESH SNOW AND GUSTY WINDS WILL PRODUCE SOME AREAS
OF BLOWING/DRIFTING SNOW.
00Z SATURDAY THROUGH 00Z SUNDAY...MAINLY VFR CONDITIONS AS HIGH
PRESSURE BUILDS INTO THE REGION. LINGERING MVFR SNOW SHOWERS
POSSIBLE AT MPV/SLK THRU 06Z SATURDAY.
00Z SUNDAY THROUGH MONDAY...MAINLY VFR CONDITIONS WITH A CHANCE OF
MVFR SNOW SHOWERS ACROSS CENTRAL AND SOUTHERN AREAS SATURDAY NIGHT
AS LOW PRESSURE PASSES SOUTH AND EAST OF THE REGION.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...WINTER STORM WARNING UNTIL 7 AM EST FRIDAY FOR VTZ001>012-
016>019.
NY...WINTER STORM WARNING UNTIL 7 AM EST FRIDAY FOR NYZ026>031-034-
035-087.
&&
$$
SYNOPSIS...NASH
NEAR TERM...RJS/MUCCILLI
SHORT TERM...NASH
LONG TERM...TABER
AVIATION...LAHIFF
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1252 AM EST THU DEC 27 2012
.SYNOPSIS...
A STRONG WINTER STORM WILL IMPACT THE AREA TONIGHT LEADING TO
HEAVY SNOW ACCUMULATIONS ACROSS THE ENTIRE FORECAST AREA. WRAP
AROUND MOISTURE WILL THEN RESULT IN CONTINUED SNOWS FOR MUCH OF
CENTRAL NEW YORK ON THURSDAY BEFORE HIGH PRESSURE SLOWLY BUILDS
INTO THE AREA TOWARDS THE CONCLUSION OF THE WEEK.
&&
.NEAR TERM /THROUGH TODAY/...
10 PM UPDATE... WELL DEFINED AND NARROW DRY SLOT CONTS ITS NWD
CHARGE ATTM...ALG THE I-81 CORRIDOR. THUS...PCPN HAS AT LEAST
TEMPORARILY TAPERED OFF...AND ALSO MIXED WITH SLEET/-FZRA...FROM
ABT KBGM SWD TWDS W-B/SCRANTON. MEANWHILE...INTERESTINGLY...HVYR
PCPN (MAINLY SNOW) CONTS ACRS THE WRN CATSKILLS AND
POCONOS...LIKELY IN RESPONSE TO INCRD FGEN FORCING...ASSOCD WITH
DVLPG SFC/MID-LVL CYCLONES ACRS THE DELMARVA RGN. ALSO...HVY SNOW
PERSISTS TO OUR W AND N...TIED TO ORIGINAL BAND OF STG ISEN LIFT.
WHAT HAPPENS FROM HERE ON IN?? WELL...THE LATEST RAPID REFRESH
DATA...ALG WITH INCOMING 00Z NAM/GFS OUTPUT...HAS COME INTO LINE
PRETTY WELL...SUGGESTING THAT HVYR PCPN WILL BE MOST SUSTAINED
JUST W OF THE I-81 CORRIDOR IN THE 06-10Z TIME FRAME...AS THE BEST
FORCED LIFT TENDS TO CONSOLIDATE IN THIS RGN. HVYR PCPN NOW ACRS
OUR SERN ZNS...SHOULD HAVE A TENDENCY TO BECOME LGTR AND MORE
SPOTTY AFTER MIDNIGHT...UNDERNEATH EXPANDING DRY SLOT ALOFT.
AS LOW-LVL CAA/VEERING BLYR WINDS START TO KICK IN TWDS
DAYBREAK...AS THE MAIN STORM BCMS MORE VERTICALLY STACKED NEAR
NYC...A GENERAL AND LGTR WRAP-ARND SNOW PATN SHOULD BEGIN TO
BECOME ESTABLISHED.
AGN...BOTTOM LN...NOT MUCH CHG MADE TO OVERNIGHT SNOW ACCUMS/STORM
TOTALS. HVYR AMTS...AS EXPECTED...WILL LIKELY END UP OVER WRN AND NRN
PTNS OF THE FA. SOME 6"+ SNOW TOTALS ALSO SEEN AS FAR SEWD AS SXNS
OF THE TWIN TIERS/CHENANGO/OTSEGO CNTYS...AND SULLIVAN/PIKE/WAYNE
CNTYS IN THE POCONOS/WRN CATSK.
PREV UPDATE... 8 PM UPDATE... RADAR/SAT LOOPS SHOW A WELL DEFINED
DRY SLOT HEADING NWD THROUGH ERN PA ATTM. THE LATEST RAPID REFRESH
MODEL RUNS...AND ALSO THE 18Z NWP GUIDANCE SHOW THIS FEATURE...BUT
HAVE NOT QUITE CAUGHT ON TO ITS QUICK NWD MOVEMENT. THUS...WE`VE
SPED UP THE TRANSITION FROM STEADY HVY SNOW...TO LGTR SNOW...OR A
LGT MIX...GENERALLY OCCURRING FROM 00-03Z...ALG AND JUST E OF THE
I-81 CORRIDOR.
ALSO...THE CHARACTER OF THE RADAR ECHOES...PLUS
PLENTIFUL SPOTTER/PUBLIC REPORTS...SHOW A HODGE-PODGE OF
SNOW...SLEET...FZRA BASICALLY ALG AND S OF ROUTE 6 IN NRN PA ATTM.
THIS AREA OF MIXED PCPN WILL PROBABLY EXTEND TO ABT THE I-88
CORRIDOR IN SRN NY TWDS 03-04Z...BUT WE DON`T EXPECT IT TO MOVE
ANY FARTHER TO THE N OR W.
AT THIS JUNCTURE...WE DON`T SEE A LOT OF EVIDENCE THAT THE ERLY
FLOW/TERRAIN INDUCED PCPN SHADOWING...CONSISTENTLY SHOWN BY MANY
OF OUR HI-RES MODELS FOR THIS EVE...HAS DVLPD...OR WILL DVLP.
WE`LL SEE HOW THE DRY SLOT ADVANCING ACRS PA DVLPS LTR THIS
EVE...IN THIS REGARD.
BOTTOM LN...WE`RE NOT MAKING ANY SUBSTANTIVE CHGS TO OUR SNOW
TOTALS. INITIAL BURST OF VERY HVY SNOW IN OUR FAR SRN ZNS IN THE MID TO
LATE AFTN HRS...HAVE BROUGHT SNOW TOTALS INTO THE 3-6" RANGE ATTM.
GIVEN MIXED PCPN THESE AREAS CURRENTLY...TOTALS WILL LIKELY NOT GO
A GREAT DEAL HIGHER. ACRS THE TWIN TIERS...VERY HVY SNOW THE LAST
SVRL HRS...IS LIKELY TO SLOW DOWN A BIT THROUGH ABT
06Z...ESPECIALLY S AND E OF A TOWANDA TO KBGM TO ONEONTA LN. SNOW
TOTALS HAVE RANGED FROM 4-8" IN MANY LOCALES THROUGHOUT THESE
AREAS SO FAR.
FOR MANY OF OUR NRN AND WRN ZNS...HVY SNOW BANDS WILL CONTINUE TO
ROTATE ACRS THROUGH AT LEAST 06Z...AS MID-LVL FGEN MAXIMIZES...AND
THETA-E LR`S ALOFT DECREASE ON THE LEADING EDGE OF THE DRY SLOT.
ISOLD THUNDER-SNOW NOT OUT OF THE QUESTION...AND IN FACT...SOME
OF THIS HAS ALREADY BEEN REPORTED IN CHENANGO CNTY. STORM TOTALS
OF A FOOT OR MORE WILL BE MOST PROBABLE THESE PTNS OF THE FA.
OVERALL...ONLY MINOR TWEAKS MADE...TO BEST REFLECT THE LATEST
RADAR/TEMP TRENDS. NEAR-TERM SPS`S AND FREQUENT WSW UPDATES WILL
CONTINUE TO BE ISSUED.
EARLIER DISC... CONDITIONS RAPIDLY DETERIORATING ACROSS THE AREA THIS
AFTERNOON AS LONG ADVERTISED WINTER STORM GETS UNDERWAY. REGIONAL
WATER VAPOR IMAGERY SHOWING MAIN MID-LEVEL CIRCULATION SLIDING
ACROSS THE EASTERN TN/KY BORDER THIS AFTERNOON...WITH NOTABLE DRY
SLOT BEGINNING TO WORK NORTH TOWARDS PIT AS SYSTEM CONTINUES THE
OCCLUSION PROCESS. LATEST RUC TROP PRESSURE FIELD SHOWS MAIN WAVE
NOW TAKING ON A NEGATIVE TILT WHICH SUGGEST UPPER FEATURE IS
REACHING MATURITY. MEANWHILE ALONG THE SURFACE...SECONDARY LOW
PRESSURE DEVELOPMENT NOW TAKING SHAPE ACROSS THE NORTH CAROLINA
PIEDMONT REGION...WITH SFC PRESSURE FIELDS REVEALING A NOTABLE
COLD AIR DAMMING SIGNATURE ALONG THE EASTERN SPIN OF THE
APPALACHIANS. IF NOTHING LESS...THE PRESENCE OF THIS SIGNATURE
WILL HELP ENSURE CONDITIONS ARE PRE-CONDITIONED FOR A ROUND OF
HEAVY SNOWFALL ACROSS THE FCST AREA TONIGHT AS WARM AIR ADVECTION
FORCING INCREASES IN ADVANCE OF THE SECONDARY LOW PRESSURE
SYSTEM/S MOVEMENT UP THE EAST COAST.
THE ABOVE SAID...LATEST RADAR TRENDS SHOWING SNOW MAKING STEADY
PROGRESS NORTHWARD THIS AFTERNOON WITH SNOW ALREADY BEING
REPORTED AT BOTH ELM AND AVP. QUICK INSPECTION OF RUC LAYERED
THETA-E LAPSE RATES SUGGEST A FAIR AMOUNT OF CONDITIONAL
INSTABILITY EXISTS ALOFT WHICH WILL LEAD TO SNOWFALL RATES ON THE
ORDER OF 2-3`/HR UNDER THE HEAVIEST ACTIVITY. DESPITE THE FACT THE
STORM IS ALREADY ONGOING ACROSS THE AREA...A FAIR AMOUNT OF MODEL
UNCERTAINTY STILL EXISTS WITH EXPECTED CONDITIONS OVERNIGHT AS THE
SECONDARY LOW PASSES TO OUR SOUTH AND EAST. WHAT DOES APPEAR FOR
CERTAIN IS THAT THE HEAVIEST SNOWFALL WILL OCCUR BETWEEN NOW AND
06Z AS THE MAIN AREA OF FRONTOGENESIS AND WARM AIR ADVECTION
FORCING LIFTS THROUGH THE FCST AREA. UNFORTUNATELY THIS WILL OCCUR
DURING THE AFTERNOON COMMUTE WHICH WILL UNDOUBTEDLY MAKE THINGS
DICEY FOR THOSE HEADING HOME THIS EVENING. MODELS CONTINUE TO
INSIST ON THE PREVIOUSLY MENTIONED DRY SLOT MOVING NORTH INTO OUR
AREA AFTER 06Z WHICH WILL LEAD TO A FAIR AMOUNT OF DRYING WITHIN
THE DENDRITIC SNOW GROWTH REGION. AS A RESULT...WE EXPECT TO SEE
THE HEAVY SNOW ZONE GRADUALLY ROTATE TO THE WEST WITH TIME AS A
POORLY DEFINED DEFORMATION AXIS ATTEMPTS TO FORM AFTER 06Z.
FURTHER TO THE EAST...PRONOUNCED DRY AIR ALOFT WILL LIKELY LEAD TO
A GRADUAL DECREASE IN SNOWFALL INTENSITY FOR THE SUSQUEHANNA
VALLEY REGION OF CENTRAL NY AND POINTS SOUTH TO INCLUDE THE TWIN
TIERS...POCONOS...AND LOWER WYOMING VALLEY. DESPITE THE PRESENCE
OF THE DRY SLOT...FORECAST MODELS CONTINUE TO PRODUCE LIGHT QPF
ACROSS THESE REGIONS WHICH LEADS US TO BELIEVE THAT FREEZING RAIN
AND PERHAPS SOME SLEET WILL BEGIN FOR THESE AREAS TOWARDS THE
EARLY MORNING HRS. IF THIS WERE TO OCCUR AS ADVERTISED...A FAIRLY
HEALTHY ICING EVENT MAY HAPPEN FOR THOSE LOCATIONS. FOR NOW WE
EXPECT THE HEAVIEST ICING TO OCCUR ACROSS THE WYOMING VALLEY AND
SOUTHERN POCONOS WHERE A QUARTER INCH OR MORE OF ICE WILL BE POSSIBLE.
ANOTHER INTRIGUING ASPECT OF THIS STORM IS THAT ALL MODELS TO
INCLUDE THE LOWER RESOLUTION ECMWF SHOW A SHADOWING EFFECT JUST
WEST OF THE CATSKILLS AFTER 06Z THIS EVENING. THIS SEEMS PLAUSIBLE
TO SOME DEGREE AS A STRONG EASTERLY LOW-LEVEL JET OF 70+KTS
IMPINGES ON THE MOUNTAIN RANGE. FOR NOREASTER TYPE EVENTS THIS
SEEMS VERY UNUSUAL HOWEVER WITH ALL SHORT TERM MODEL PROGS
CONTINUING TO INSIST THIS WILL OCCUR...HAVE ELECTED TO LOWER
SNOWFALL TOTALS ACROSS THE WESTERN CATSKILLS JUST A TAD.
SO TO SUM THINGS UP...THE HEAVIEST SNOWS ARE EXPECTED FROM THE
CHEMUNG RVR VLY NORTHEAST TROUGH THE FINGER LAKES AND WESTERN
MOHAWK VALLEY. ACROSS THESE LOCATIONS...ANYWHERE BETWEEN 10-14"
WILL BE POSSIBLE. FURTHER SOUTH AND EAST...8-10" ARE FORECAST
ACROSS THE TWIN TIERS AND WESTERN CATSKILLS...WITH 4-6" EXPECTED
FOR THE SOUTHERN CATSKILLS...POCONOS AND LOWER WYOMING VLY. NO
CHANGES MADE TO INHERITED HAZARDS WITH THE EXCEPTION OF BEEFING UP
THE WORDING FOR POTENTIAL ICE ACCUMULATIONS ACROSS THE SOUTH.
FOR THURSDAY...EXPECT SOME LINGERING WRAP AROUND MOISTURE TO LEAD
TO CONTINUED SNOW ACROSS PORTIONS OF UPSTATE NY. H85 TEMPS LOOK A
TAD TOO WARM TO RESULT IN ANY SIGNIFICANT LAKE ENHANCEMENT. WILL
CONTINUE TO CARRY LIKELY POPS ACROSS THE NORTH WITH SLGT CHC-CHC
TO THE SOUTH.
&&
.SHORT TERM /TONIGHT THROUGH 6 PM FRIDAY/...
STORM MOVES AWAY FROM THE AREA THURSDAY NIGHT. EXPECT SOME LIGHT
LAKE EFFECT SNOW SOUTH-SOUTHEAST OF LAKE ONTARIO WITH A 320 TO 325
DEGREE FLOW AND SOME LINGERING MOISTURE. HOWEVER WITH MARGINAL
TEMPERATURES AROUND -8 TO -10 DEGREES C AT 850 MB AND INVERSION HGTS
GENERALLY BELOW 5000 FEET EXPECT ONLY LIGHT ACCUMULATIONS... MAYBE
AROUND 2 INCHES ACROSS CENTRAL NY DOWN THROUGH AREAS SOUTHEAST OF
THE FINGER LAKES. DRYING MOVES IN WITH A WEAK RIDGE OF HIGH PRESSURE
ON FRIDAY PUTTING AN END TO ANY LINGERING LIGHT SNOW SHOWERS OR
FLURRIES DURING THE DAY.
NEXT SYSTEM APPROACHES THE AREA LATER FRIDAY NIGHT INTO SATURDAY.
MODEL CONSENSUS WITH THIS NEXT SYSTEM INDICATES A WEAK INVERTED
SURFACE TROUGH TRACKING ACROSS THE AREA WITH SOME LIGHT SNOW... BUT
SIGNIFICANT DEVELOPMENT OF THE SURFACE LOW DOES NOT OCCUR UNTIL THE
STORM IS WELL EAST OF THE MID-ATLANTIC COAST. THEREFORE HEAVY SNOW
DOES NOT APPEAR LIKELY AT THIS TIME.
.LONG TERM /SUNDAY THROUGH TUESDAY...
GFS AND ECMWF ARE IN REASONABLY GOOD AGREEMENT WITH THE OVERALL
PATTERN DURING THIS PERIOD INDICATING NORTHWEST FLOW WITH A SERIES
OF WEAKLY ORGANIZED CLIPPER SYSTEMS LIKELY ALONG WITH SOME LAKE EFFECT
SNOW. HOWEVER AT THIS POINT THERE IS NO INDICATION FOR ANY MAJOR
SYNOPTIC SCALE SYSTEMS THAT WOULD TAP GULF MOISTURE. TIMING OF THESE
INDIVIDUAL SYSTEMS WILL BE DIFFICULT BEYOND SUNDAY... BUT RIGHT NOW
THE BEST CHC FOR A WEAKLY ORGANIZED CLIPPER-LIKE SYSTEM COULD BE NEW
YEAR`S EVE INTO NEW YEAR`S DAY... WHICH WOULD BE FOLLOWED BY AN
ENHANCED PERIOD OF LAKE EFFECT SNOW. TEMPERATURES THROUGH THE PERIOD
WILL AVERAGE NEAR TO BELOW NORMAL... WITH HIGHS MAINLY IN THE MID
20S TO LOWER 30S AND LOWS IN THE TEENS. HAVE GONE WITH HPC GUIDANCE
THROUGH THE PERIOD INDICATING BEST CHANCES FOR SNOW WILL BE OVER
CENTRAL NY WITH SMALLER CHANCES TOWARD NORTHEAST PA.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
GFS AND ECMWF ARE IN REASONABLY GOOD AGREEMENT WITH THE OVERALL
PATTERN DURING THIS PERIOD INDICATING NORTHWEST FLOW WITH A SERIES
OF WEAKLY ORGANIZED CLIPPER SYSTEMS LIKELY ALONG WITH SOME LAKE EFFECT
SNOW. HOWEVER AT THIS POINT THERE IS NO INDICATION FOR ANY MAJOR
SYNOPTIC SCALE SYSTEMS THAT WOULD TAP GULF MOISTURE. TIMING OF THESE
INDIVIDUAL SYSTEMS WILL BE DIFFICULT BEYOND SUNDAY... BUT RIGHT NOW
THE BEST CHC FOR A WEAKLY ORGANIZED CLIPPER-LIKE SYSTEM COULD BE NEW
YEAR`S EVE INTO NEW YEAR`S DAY... WHICH WOULD BE FOLLOWED BY AN
ENHANCED PERIOD OF LAKE EFFECT SNOW. TEMPERATURES THROUGH THE PERIOD
WILL AVERAGE NEAR TO BELOW NORMAL... WITH HIGHS MAINLY IN THE MID
20S TO LOWER 30S AND LOWS IN THE TEENS. HAVE GONE WITH HPC GUIDANCE
THROUGH THE PERIOD INDICATING BEST CHANCES FOR SNOW WILL BE OVER
CENTRAL NY WITH SMALLER CHANCES TOWARD NORTHEAST PA.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
LRG STORM STILL DEEPENING AS IT MVES UP THE NJ CST. THIS WILL KEEP
SNOW OVER THE AREA...AND SOME MIXED PCPN AT AVP...THRU AT LEAST
12Z. CIGS AND VSBYS WILLVARY WIDELY AS BANDS OF HEAVIER PCPN MVE
THRU...BUT WILL BE IFR ON BALANCE...WITH OCNL PDS OF BOTH LIFR AND
MVFR. CONDS WILL IMPROVE A BIT AFT 12Z AS THE UPR LOW AXIS MVES BY
AND THE AREA IS ON THE BACKSIDE OF THE STORM. HWVR...PERSISTENT
LGT SNOW WILL KEEP CIGS AND VSBY AT LEAST IN THE MVFR CAT THRU THE
END OF THE PD.
OUTLOOK...
THUR NGT...MVFR/IFR IN SNOW SHOWERS ESPECIALLY OVER CENTRAL NY.
FRI...MAINLY VFR...MVFR/IFR POSSIBLE NORTHERN TERMINALS IN LAKE
EFFECT SNOW.
SAT...ANOTHER POSSIBLE WINTER SYSTEM AND THUS POSSIBLE IFR/MVFR.
SUN/MON...MVFR/IFR POSSIBLE AT FOR CNY TERMINALS IN DEVELOPING LAKE
EFFECT SN.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...WINTER STORM WARNING UNTIL 1 PM EST THIS AFTERNOON FOR
PAZ038>040-043-044-047-048-072.
NY...WINTER STORM WARNING UNTIL 1 PM EST THIS AFTERNOON FOR NYZ009-
015>018-022>025-036-037-044>046-055>057-062.
&&
$$
SYNOPSIS...CMG
NEAR TERM...CMG/MLJ
SHORT TERM...DGM
LONG TERM...PVN
AVIATION...DGM
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
1236 AM EST THU DEC 27 2012
.SYNOPSIS...
A POTENT WINTER STORM WILL IMPACT THE ENTIRE REGION TONIGHT
THROUGH THURSDAY NIGHT PRODUCING WIDESPREAD HEAVY SNOWS WITH
AMOUNTS OVER A FOOT. GUSTY WINDS WILL ALSO OCCUR ALONG THE WESTERN
SLOPES OF THE GREEN MOUNTAINS AND IN THE SAINT LAWRENCE VALLEY,
AND THIS MAY CAUSE AREAS OF BLOWING SNOW. SNOW SHOWERS WILL
CONTINUE ACROSS THE NORTHERN MOUNTAINS ON FRIDAY AS THE STORM
MOVES AWAY FROM THE REGION. THE WEEKEND WILL BE SEASONABLY COLD,
WITH A CONTINUED CHANCE OF LIGHT SNOW IN THE MOUNTAINS.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
AS OF 1227 AM EST THURSDAY...EVERYTHING STILL ON TRACK WITH ONLY
MINOR ADJUSTMENTS MADE TO GOING FORECAST. LOW PRESSURE IS LOCATED
NEAR TIP OF SOUTHERN NEW JERSEY AT 992 MB. GREATEST PRESSURE FALLS
ARE ALONG THE NEW JERSEY COASTLINE...CONTINUING TO SUGGEST A TRACK
TOWARDS LONG ISLAND OVERNIGHT. SNOW HAS MADE IT AS FAR NORTH AS
BURLINGTON AND MASSENA AND WILL OVERSPREAD REST OF NORTHERN
VERMONT OVER NEXT COUPLE OF HOURS. INTENSITY OF SNOW INCREASES
QUICKLY AFTER ONSET. HAVE SEEN WIDESPREAD 1-2" PER HOUR RATES
ACROSS NEW YORK AND SOUTHERN VERMONT AS WELL AS POINTS FURTHER
SOUTH. LATEST HRRR CONTINUES TO SHOW THIS HEAVY BAND MOVING
NORTHWARD...WITH HEAVIEST PRECIP THROUGH 8Z IN SOUTHERN
AREAS...5-10Z IN THE CHAMPLAIN VALLEY AND NORTHERN VERMONT...AND
7-13Z ACROSS NORTHERN NEW YORK. ALSO OF NOTE...DOWNSLOPE WINDS
GUSTING INTO THE 20S ACROSS SOUTHWEST VERMONT.
EARLIER DISCUSSION FROM 642 PM EST...
EVERYTHING REMAINS ON TRACK...AND ONLY MINOR ADJUSTMENTS WERE
MADE. HAD TO DROP TEMPERATURES SLIGHTLY THIS EVENING...WITH
WIDESPREAD TEENS ACROSS THE REGION. LOWS WILL BE REACHED OVER THE
NEXT COUPLE OF HOURS...AND THEN SLOWLY RISE OVERNIGHT.
OTHERWISE...TRIED TO NARROW DOWN THE START TIME FOR SNOW ACROSS
THE AREA. PRIMARY LOW NOW LOCATED OVER WEST VIRGINIA WITH A
SECONDARY LOW DEVELOPING NEAR WAKEFIELD VIRGINIA. SECONDARY LOW
WILL TAKE OVER DURING THE REST OF THE EVENING AND PROGRESS TO NEAR
DELAWARE BY 03Z...NEW YORK CITY BY 09Z....AND THEN LONG ISLAND BY
12Z. JUDGING BY CURRENT OBSERVATIONS...SNOW HAS NOW REACHED AS FAR
NORTH AS THE MID-HUDSON VALLEY...THE CENTRAL MOHAWK VALLEY...AND
THE SHORES OF LAKE ONTARIO IN NEW YORK...WITH A SLOW NORTHWARD
PROGRESSION. SHOULD BE INTO THE ADIRONDACKS AND SOUTHERN VERMONT
AROUND 02Z (9 PM)...THE CHAMPLAIN VALLEY AROUND 04Z (11 PM)...AND
THE NORTHEAST KINGDOM AROUND 05Z (MIDNIGHT). HEAVIEST SNOW WITH
INITIAL BAND OF WARM AIR ADVECTION PRECIPITATION WILL LIKELY OCCUR
BETWEEN 07Z AND 10Z (2 AM AND 5 AM) WHERE RATES OF 1-2 INCHES PER
HOUR ARE POSSIBLE...ESPECIALLY IN THE SOUTHEAST- UPSLOPE FAVORED
LOCATIONS. DOWNSLOPE WINDS WILL ALSO BE INCREASING ACROSS THE
SOUTHERN GREENS WITH GUSTS UP TO 40 MPH POSSIBLE IN EASTERN
ADDISON AND RUTLAND COUNTIES BETWEEN 06Z AND 10Z (1 AM AND 5 AM).
THIS WILL CREATE SOME WARMING AND DRYING IN THOSE AREAS...AND
COMBINED WITH SOME WARMING ALOFT (750-800 MB) AS INDICATED BY
LATEST RAP AND NAM...WILL LIKELY SEE SOME SLEET MIX IN ACROSS
RUTLAND AND WINDSOR COUNTIES AFTER 07Z...AND ESPECIALLY AFTER 10Z.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH FRIDAY NIGHT/...
AS OF 325 PM EST WEDNESDAY...GONNA BE A BUSY DAY THURSDAY. LOTS OF
SNOW. THE STORM WILL TRACK NORTHEAST AND CUT ACROSS CAPE COD (OR
VERY NEAR IT) BY LATE IN THE AFTERNOON. THIS PUTS THE NORTH
COUNTRY INTO A SWEET SPOT FOR THE HEAVIEST QPF. THE DRY SLOT JUST
WONT GET THIS FAR NORTH, AND AS THE LOW MOVES OFF TO THE EAST,
WE`LL BE IN THE PIVOT ZONE INTO THE AFTERNOON.
EXCELLENT DYNAMICS AND SNOW GROWTH MAXED WITH UPWARD MOTION
SHOULD RESULT IN A PERIOD OF HEAVY SNOW MOST EVERYWHERE. THINKING
THE PRIMARY TIME WILL BE 6AM TO NOON, WITH RATES OF 1-2" PER HOUR.
CAN`T RULE OUT LOCALIZED MESOSCALE BAND WITH EVEN A LITTLE BIT
MORE. LIQUID QPF WILL BE QUITE IMPRESSIVE. SPENT A GOOD DEAL OF
TIME TRYING TO ACCOUNT FOR OROGRAPHIC EFFECTS AS WELL. BY THE TIME
WE GET TO THURSDAY NIGHT, MOST OF US WILL SEE ON THE ORDER OF 1 TO
1.5" OF LIQUID EQUIVALENT. SHADOWING WILL MAKE THE NUMBER A LITTLE
LOWER IN THE NORTHEAST KINGDOM AND WESTERN SLOPES OF THE SOUTHERN
GREENS, BUT THEN THAT ON THE FLIP SIDE, ORGRAPHICS WILL HELP ON
THE EASTERN SIDES OF THE GREENS AND DACKS. HAVE INCREASED THE SNOW
TOTALS A FEW INCHES ACROSS THE BOARD -- THINKING 12 TO 17 INCHES,
WITH THE JACKPOT LOCATIONS SEEING ABOUT 20". EVEN THOSE WHO SEE
THE LEAST WILL GET ABOUT 8", WHICH IS NOT SHABBY.
WINDS WILL CONTINUE TO BE GUSTY THE FIRST HALF OF THURSDAY ALONG
THE WESTERN SLOPES. ALSO HAVE TO WATCH FOR STRONG NORTHEAST WINDS
FUNNELLING DOWN THE ST LAWRENCE VALLEY. DONT THINK THEY`LL HIT
WIND ADVISORY CRITERIA, BUT STILL THEY`LL HAVE SUSTAINED WINDS 15
TO 25 MPH WITH HIGHER GUSTS -- AND THAT WILL CAUSE A CONSIDERABLE
AMOUNT OF DRIFTING/BLOWING SNOW OUT THERE. HAVE ADDED THAT WORDING
TO THE FORECAST.
SNOW WILL BEGIN TO TAPER OFF IN THE EVENING, THOUGH LIGHT SNOWS
WILL CONTINUE ALL NIGHT. AS THE LOW PUSHES EAST OF HERE, WINDS
WILL CLOCK AROUND TO NORTHWEST. MOISTURE WILL BE SLOW TO LEAVE, SO
THE NORTHWEST WINDS AND THAT MOISTURE WILL RESULT IN A GOOD AMOUNT
OF OROGRAPHICS, SO THE HIGHER TERRAIN WILL PICK UP A FEW
ADDITIONAL INCHES OF SNOW (AT LEAST) ON FRIDAY.
FINALLY TAPER POPS DOWN TO CHANCE LEVELS BY FRIDAY NIGHT, THOUGH A
WEAK SYSTEM APPROACHING FROM THE WEST MAY SPARK A LITTLE BIT OF
LIGHT SNOW/FLURRIES.
QUICK NOTE ON TEMPERATURES -- PRIMARILY KEPT TO THE COOLER SIDE OF
GUIDANCE FOR THE ENTIRE TIME.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AS OF 342 PM EST WEDNESDAY...OVERALL LITTLE CHANGE FROM PREVIOUS
COUPLE OF FCSTS...WITH BLW NORMAL TEMPS AND PRECIP EXPECTED FOR
DAYS 4 THRU 7. THE EXTENDED FCST CHALLENGE WL BE TIMING/MAGNITUDE
OF ARCTIC AIRMASS ACRS OUR CWA EARLY NEXT WK. WL CONT TO MENTION
LOW CHC POPS FOR LATE SAT INTO SUNDAY ASSOCIATED WITH MID/UPPER
LVL TROF AND SOME 850 TO 500MB RH. LATEST TRENDS HAVE BEEN FOR
LESS RH AND QPF ACRS OUR CWA...BUT ECMWF IS A BIT CLOSER TO THE
COAST WITH SFC LOW PRES AND ENOUGH MOISTURE MAY MOVE BACK INTO OUR
CWA FOR SOME LIGHT SNOW. OTHERWISE...ECMWF/GEM SHOW MID/UPPER LVL
TROF DEVELOPING ACRS EASTERN CANADA WITH A MAINLY DRY NW FLW
ALOFT. HOWEVER...A WELL DEFINED ARCTIC BOUNDARY WL PUSH ACRS OUR
CWA EARLY NEXT WEEK...ALONG WITH A RIBBON OF ENHANCED MOISTURE.
THIS MOISTURE...ALONG WITH SOME ADDITIONAL MOISTURE FROM THE GREAT
LAKES WL HELP IN PRODUCING SOME SNOW SHOWERS ACRS OUR CWA ON
MONDAY INTO TUES. IN ADDITION...MUCH COLDER TEMPS WL ADVECT BACK
INTO OUR CWA FOR NEXT WK. STILL SOME UNCERTAINTY WITH REGARDS TO
TIMING OF THIS FEATURE...AS GFS IS 6 TO 12 HRS SLOWER AND SHOWS
THE COLDEST TEMPS ACRS OUR CWA ON WEDS. TIMING OF BOUNDARY WL MAKE
A HUGE DIFFERENCE IN TEMPS FROM NEAR 30F AT BTV IF THE GFS IS
RIGHT TO LOWER TEENS IF THE ECMWF/GEM ARE CORRECT ON TUES. GIVEN THE
DEVELOPMENT OF A LARGE SCALE TROF AND DEEP CYCLONIC FLW ACRS THE
NE CONUS...WL TREND TWD THE COLDER ECMWF/GEM FOR NEXT WEEK...AND
MENTION HIGHS ONLY IN THE TEENS/L20S WITH LOWS MAINLY IN THE
SINGLE DIGITS/LOWER TEENS. IF SFC HIGH PRES BUILDS INTO THE
REGION...FASTER THAN PROGGED...THEN WINDS WL DECREASE AND
OVERNIGHT LOWS WL NEED TO BE ADJUSTED DOWN BY 5 TO 10 DEGREES. ITS
ALWAYS DIFFICULT TO DETERMINE AMOUNT OF CAA AND IMPACTS ACRS OUR
CWA IN THE DAY 5 TO 7 RANGE. TODAY IS A GREAT EXAMPLE OF TRYING TO
PREDICT THE COLD AIR...AS TEMPS STRUGGLED MAINLY IN THE TEENS.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
THROUGH 00Z FRIDAY...SNOW TO MOVE IN TO ALL TAF SITES 03-05Z,
LOWERING CONDITIONS TO LIFR TO IFR FOR ALL OF TAF PERIOD. HEAVIER BURSTS
POSSIBLE 09-14Z AT HEIGHT OF STORM. AFTER 14Z WILL BEGIN TO SEE
SLOW IMPROVEMENT...BUT STILL IFR. POTENTIAL FOR LAYER OF NEAR TO
ABOVE FREEZING AIR TO MOVE IN TO SOUTHERN VERMONT 10-15Z...AND
PRODUCE SLEET AT KRUT. TEMPERATURE PROFILE RIGHT ON THE EDGE...AND
COULD EASILY STAY ALL SNOW IF TEMPERATURES REMAIN COOL ENOUGH.
EAST TO SOUTHEAST LOW LEVEL JET TO MOVE INTO AREA OVERNIGHT...WITH
KRUT LIKELY TO EXPERIENCE STRONGEST WIND GUSTS 20-35 KTS. VALLEY
CHANNELING AT KMSS WILL PRODUCE GUSTS TO 20-25 KTS. ELSEWHERE
STRONGER WINDS LESS FAVORABLE... REMAINING SITES STILL TO SEE
15-20 KTS.
OUTLOOK 00Z FRIDAY THROUGH MONDAY...
00Z FRIDAY-00Z SATURDAY...LOW WILL MOVE INTO THE GULF OF
MAINE...SHIFTING SURFACE WINDS TO NORTHWEST. SNOW SHOWERS TO
CONTINUE ESPECIALLY IN FAVORED UPSLOPE AREAS...AND HIGHER
ELEVATION SITES KMPV/KSLK LIKELY WILL SEE CONTINUED MVFR TO IFR
CIG/VIS. MOSTLY VFR ELSEWHERE...ALTHOUGH FRESH SNOW AND GUSTY
WINDS WILL PRODUCE SOME BLOWING/DRIFTING.
00Z SATURDAY THROUGH 00Z SUNDAY...SFC HIGH PRES SLOWLY BUILDS INTO
OUR TAF SITES BY 12Z SATURDAY. SOME LEFTOVER MTN SNOW SHOWERS AT
MPV/SLK WL CREATE OCCASIONAL MVFR CONDITIONS THRU 06Z SAT...BEFORE
DISSIPATING WITH VFR CONDITIONS DEVELOPING AFT 06Z SATURDAY.
00Z SUNDAY THROUGH MONDAY...MAINLY VFR CONDITIONS WITH A CHANCE OF
MVFR SNOW SHOWERS ACROSS CENTRAL AND SOUTHERN AREAS SATURDAY NIGHT
AS LOW PRESSURE MOVES EAST ACROSS THE MID-ATLANTIC STATES.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...WINTER STORM WARNING UNTIL 7 AM EST FRIDAY FOR VTZ001>012-
016>019.
NY...WINTER STORM WARNING UNTIL 7 AM EST FRIDAY FOR NYZ026>031-034-
035-087.
&&
$$
SYNOPSIS...NASH
NEAR TERM...RJS/MUCCILLI
SHORT TERM...NASH
LONG TERM...TABER
AVIATION...HANSON
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
436 AM EST THU DEC 27 2012
.SYNOPSIS...
LOW PRESSURE SYSTEM EXITS EAST TODAY. ANOTHER LOW PRESSURE SYSTEM
FRIDAY NIGHT AND SATURDAY...WITH MORE MIXED PRECIPITATION...CHANGING
TO SNOW OVERNIGHT SATURDAY AND SUNDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
RADAR AND MODELS SHOWING LIGHT SNOW OR FREEZING DRIZZLE MOVING INTO
THE EASTERN MOUNTAINS WHILE DIMINISHING ACROSS THE WESTERN HALF OF
THE AREA THIS MORNING. LOW CLOUDS WILL PERSIST OVER A SHALLOW
SATURATED LAYER TODAY...LIFTING TONIGHT. HOWEVER...HIGH LEVEL
CLOUDS ASSOCIATED WITH A FAR AWAY SYSTEM WILL COVER PORTIONS OF OUR
SKIES THROUGH THIS EVENING.
VERY COLD AIR CONTINUES TO FILTER IN UNDER WEST NORTHWEST FLOW WITH
H850 TEMPS WARMING FROM MINUS 9C TO MINUS 5C BY 18Z THIS AFTERNOON
AND TONIGHT. THEREFORE...WITH CLOUDS EXPECTED AND VERY COLD AIR MASS
IN PLACE...TODAYS TEMPERATURES WILL REMAIN AT OR BELOW
FREEZING...EXCEPT FOR POCKETS JUST ABOVE OVER THE LOWLANDS. THESE
LOW TEMPERATURES WILL KEEP ANY WET SURFACE FROZEN...TO PRODUCE BLACK
ICE WHERE WATER USUALLY DRAINS FROM SLOPES...AND ON EXPOSED BRIDGES
AND OVERPASSES. DRIVERS SHOULD EXERCISE CAUTION WHEN TRAVELING
TODAY.
FOR TONIGHT...DRIER CONDITIONS WITH LESS CLOUDS. LOWS GENERALLY IN
THE MID 20S LOWLANDS...RANGING TO THE TEENS HIGHER ELEVATIONS.
HOWEVER...WINDS WILL DIMINISH TONIGHT...KEEPING SIMILAR WINDCHILL AS
TODAY.
GUSTY WINDS WILL PRODUCE WINDCHILL IN THE 20S LOWLANDS...RANGING
INTO NEAR ZERO AT THE HIGHEST PEAKS NORTHEAST MOUNTAINS.
A WIND WIND ADVISORY REMAINS IN EFFECT FOR POCAHONTAS COUNTY THROUGH
AT LEAST 1 PM THIS AFTERNOON.
WENT WITH A BLEND OF THE GMOS AND RUC MODELS FOR TEMPERATURES
THROUGH THE PERIOD.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
FRIDAY A SHORT BREAK IN THE ACTIVE WEATHER PATTERN TAKES PLACE WITH
S/W RIDGE OVERHEAD AT 12Z QUICKLY MOVING EAST WITH UPPER FLOW
TURNING SOUTHWESTERLY IN ADVANCE OF THE NEXT RAPIDLY-APPROACHING
UPPER LEVEL TROUGH MOVING ACROSS THE CENTRAL MISS VALLEY AREA. SFC
HIGH PRESSURE SLIDES OFF TO THE EAST WITH RETURN SOUTHERLY FLOW.
OVERALL A PARTLY CLOUDY DAY GENERALLY SPEAKING WITH MORE CLOUDS TO
START THE DAY AND CLOUDS INCREASING ACROSS THE WEST BY END OF DAY.
LOOKS LIKE A DECENT TEMPERATURE GRADIENT FORMS ACROSS THE AREA AS A
WARM FRONTAL FEATURE SETS UP ROUGHLY FROM POCAHONTAS COUNTY WSW-WARD
TOWARDS HTS BY FRI MID-AFTERNOON. FAR NW ZONES WHERE RESIDUAL SNOW
COVER REMAINS WILL ONLY REACH THE MID/UPPER 30S WHEREAS FAR SOUTHERN
ZONES...WHERE 925MB TEMPS ARE PROGGED TO REACH AROUND 5.5C TO
6C...WILL PUSH 50 DEGREES AND POTENTIALLY INTO THE LOWER 50S. FRIDAY
NIGHT...LARGE SCALE ASCENT OVERSPREADS THE FORECAST AREA FROM WEST
TO EAST AS AFOREMENTIONED TROUGH CONTINUES TOWARD THE AREA WITH AXIS
ENTERING THE CWA AROUND 12Z SAT WITH SFC COLD FRONT MOVING INTO CWA
WITH IT. BEST DEEP LAYER MOISTURE WILL BE ALONG AND AHEAD OF SFC
FRONT SO WILL HAVE BEST OVERALL POPS DURING THE OVERNIGHT PERIOD.
MEANWHILE OVERNIGHT THE WARM FRONT QUICKLY LIFTS NORTHWARD WITH
DEVELOPING SFC LOW ACROSS NORTH OF LAKE ERIE IN SW ONTARIO. RAISED
MINS A BIT TO ACCOUNT FOR LLVL WARM ADVECTION AT 850MB...ALBEIT IT
IS RELATIVELY WEAK. AS A RESULT...WILL KEEP THE RAIN/SNOW MIX LINE
NORTH OF THE INTERSTATE 64 CORRIDOR FRI NIGHT/SAT MORNING AND ALL
SNOW ALONG AND NORTH OF A LINE ROUGHLY FROM PKB TO CKB AND ACROSS
THE HIGHER ELEVATIONS. SATURDAY AS THE INITIAL TROUGH AND COLD FRONT
CONTINUE EASTWARD...DEEP LAYER MOISTURE WANES AS DO THE HIGHER POPS.
A SOLID 3-5KFT LLVL OF SATURATION WILL REMAIN...AND AS SUCH SATURDAY
STAYS CLOUDY. MEANWHILE THE UPPER TROUGH DIGS TO THE WEST AGAIN AS
COLD ADVECTION CONTINUES BEHIND FRONT. LONG STORY SHORT...CHANCES
FOR PRECIP DWINDLE SOMEWHAT DURING THE DAY BUT RAMP BACK UP ONCE
AGAIN PARTICULARLY AFTER 21Z SAT AS SECONDARY UPPER TROUGH AXIS
APPROACHES FROM THE WEST AND MEAGER LLVL MOISTURE DEEPENS A BIT.
AIDING IN PRECIP PRODUCTION WILL BE THE STEEPENING LLVL LAPSE RATES
WITH THE UPPER TROUGH APPROACH WHICH MAY ADD A LEVEL OF CONVECTIVE
ENHANCEMENT. BY SATURDAY EVENING AND SATURDAY NIGHT A SECONDARY PUSH
OF COLD ADVECTION INTO THE AREA SHOULD RESULT IN A CHANGEOVER TO ALL
SNOW FOR THE ENTIRE AREA BY 03Z-06Z SUN. SNOW ACCUMULATIONS ARE
EXPECTED TO REMAIN LIGHT HOWEVER...WITH A DUSTING TO PERHAPS AROUND
A HALF INCH FOR MOST LOWLAND LOCATIONS AND ONE TO TWO INCHES FOR
ELEVATIONS ABOVE ABOUT 2.5KFT.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
MODELS SHOWING AN UPSLOPE EVENT DEVELOPING SATURDAY NIGHT AND
CONTINUING ON SUNDAY BEHIND A LOW PRESSURE SYSTEM. HIGH PRESSURE
THEN BUILDS IN SUNDAY NIGHT. MODELS THEN DIVERGE CONSIDERABLY ON
SOLUTIONS FOR MONDAY THROUGH WEDNESDAY. USED A BLEND OF THE GEFS AND
ECMWF ENSEMBLE MEANS DURING THIS PERIOD...WITH SLIGHTLY MORE
EMPHASIS ON THE ECMWF ENSEMBLE MEAN.
&&
.AVIATION /10Z THURSDAY THROUGH MONDAY/...
RADAR IMAGES SHOW ROTATING ECHOS JUST EAST OF PA AND NORTHERN OH.
SHALLOW MOISTURE LAYER STILL PRODUCING LIGHT FREEZING DRIZZLE OR
LIGHT SNOW UNDER STRONG GUSTY WINDS PEAKING JUST BELOW 30 KNOTS AT
HIGHER ELEVATIONS. THEREFORE...EXPECT MVFR/IFR CONDITIONS IN LOW
STRATUS OR LIGHT PCPN OVERNIGHT. CONDITIONS IMPROVING AFTER SUNSET
FROM WEST TO EAST...WITH EKN AND BKW THE LATEST TO IMPROVE AROUND
18-21Z FRIDAY.
POSSIBLE PATCHY FREEZING DRIZZLE INTO TOMORROW HIGHER ELEVATIONS.
WIND DIRECTION WILL SHIFT AROUND TO THE NORTHWEST TONIGHT INTO
TOMORROW.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z FRIDAY...
FORECAST CONFIDENCE: MEDIUM.
ALTERNATE SCENARIOS: TIMING OF PRECIPITATION TYPE TRANSITION COULD
VARY. DURATION AND EXTENT OF POSSIBLE ICE COULD VARY. DURATION AND
EXTENT OF LOWER CIGS AND VSBYS IN PRECIPITATION COULD ALSO VARY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE THU 12/27/12
UTC 1HRLY 08 09 10 11 12 13 14 15 16 17 18 19
EST 1HRLY 03 04 05 06 07 08 09 10 11 12 13 14
CRW CONSISTENCY L L L L L L L L L L L H
HTS CONSISTENCY L L L L L L L L L L H H
BKW CONSISTENCY H H H M M M L L L L L L
EKN CONSISTENCY M M M M M M L L L L L L
PKB CONSISTENCY L L L L L L L L L L L L
CKB CONSISTENCY M M H H M L L L L L L L
AFTER 12Z FRIDAY...
IFR POSSIBLE IN SNOW SATURDAY INTO SUNDAY...ESPECIALLY IN THE
MOUNTAINS.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...WIND ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR WVZ046.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...ARJ/50
NEAR TERM...ARJ
SHORT TERM...50
LONG TERM...RPY
AVIATION...ARJ
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
1046 PM MST WED DEC 26 2012
.AVIATION...06Z TAF UPDATE
CONDITIONS CONTINUE TO DETERIORATE ACROSS NORTHEAST WYOMING AND
WESTERN SOUTH DAKOTA THIS EVENING. AN UPPER LOW IS CROSSING THE
NORTHERN ROCKIES AND REDEVELOPING OVER NORTHEAST WYOMING...
PRODUCING A BROAD AREA OF LIGHT SNOW. WIDESPREAD IFR WITH LOCAL
LIFR CIGS AND VSBYS ARE FORECAST TO CONTINUE SPREADING EASTWARD. LITTLE
OR NO IMPROVEMENT IS EXPECTED UNTIL AT LEAST MIDDAY THURSDAY AS
THE WRAP AROUND CONVEYOR OF MOIST AIR MOVES LEISURELY ACROSS THE
AREA.
&&
.PREV DISCUSSION... /ISSUED 804 PM MST WED DEC 26 2012/
UPDATE...MINOR UPDATES WERE MADE TO INCREASE POPS OVER PARTS OF
NORTHEAST WYOMING AND NORTHWEST SOUTH DAKOTA WHERE PERSISTENT SNOW
BANDS HAVE DEVELOPED THIS EVENING. HRRR GUIDANCE INDICATES THESE
FEATURES WILL CONTINUE INTO THE OVERNIGHT HOURS.
&&
PREV DISCUSSION... /ISSUED 258 PM MST WED DEC 26 2012/
DISCUSSION...UPPER LEVEL ANALYSIS HAS WEAK RIDGE OVER THE SOUTH
CENTRAL PLAINS WITH LARGE TROF ACROSS THE WESTERN CONUS.
DEVELOPING SHORTWAVE OVER NORTHERN UTAH/SW WYOMING IS LIFTING OUT
OF THE TROF AT THE MOMENT. CLOUD COVER IS ON THE INCREASE ACROSS
THE FORECAST AREA. AT THE SURFACE...ARCTIC HIGH PRESSURE STILL
DOMINATES THE NORTHERN PLAINS. WEAK SURFACE LOW PRESSURE IS
STRENGTHENING ACROSS SOUTH CENTRAL WYOMING...WITH AN INVERTED TROF
EXTENDING INTO NORTHEAST WYOMING. TEMPERATURES ARE MAINLY IN THE
TEENS TO LOWER 20S ACROSS THE AREA...WITH LIGHT SOUTH TO SOUTHEAST
WINDS.
FOR TONIGHT...UPPER TROUGH WILL DIG INTO THE FOUR CORNERS AS WEAK
SHORTWAVE EJECTS INTO THE NORTHERN PLAINS. BEST DYNAMICS WILL SKIRT
JUST TO THE SOUTH OF THE FORECAST AREA...BUT WEAK ENERGY AND FORCING
ASSOCIATED WITH MAIN TROF WILL BRING ANOTHER ROUND OF SNOW TO THE
AREA. SNOW WILL BEGIN THIS EVENING ACROSS NORTHEAST WYOMING AND
FAR WESTERN SOUTH DAKOTA...AND SPREAD EASTWARD LATER TONIGHT. SNOW
ACCUMULATIONS OF AROUND AN INCH WILL BE POSSIBLE ACROSS WESTERN
AREAS OVERNIGHT. TEMPERATURES WILL FALL INTO THE SINGLE DIGITS FOR
MOST LOCATIONS.
ON THURSDAY...UPPER TROF CROSSES THE AREA AS MID LEVEL CLOSED LOW
SLIDES THROUGH NEBRASKA. SURFACE LOW REMAINS WELL SOUTH OF THE
AREA AS ARCTIC HIGH DOMINATES. INVERTED SURFACE TROF SLIDES ACROSS
THE DAKOTAS...SWITCHING WINDS FROM EAST SOUTHEAST TO THE NORTH.
BEST ENERGY/SNOWFALL WILL REMAIN OVER NORTHEAST WYOMING...THE
NORTHERN BLACK HILLS...AND NORTHWEST SOUTH DAKOTA WITH THIS SYSTEM.
LATER IN THE DAY...CLOSED MID LEVEL LOW OVER NEBRASKA WILL
ORGANIZE...AND PRODUCE A MODERATE BAND OF SNOW OVER SOUTH CENTRAL
SOUTH DAKOTA THROUGH THURSDAY NIGHT. SNOWFALL TOTALS SHOULD BE
AROUND 2 TO 3 INCHES FROM NORTHEAST WYOMING...THE NORTHERN
HILLS...INTO NORTHWEST SOUTH DAKOTA BY THURSDAY EVENING. SOUTH
CENTRAL SOUTH DAKOTA SHOULD ALSO SEE ABOUT 2 TO 3 INCHES. IN
BETWEEN...1 TO 2 INCHES WILL BE POSSIBLE. WITH ABUNDANT CLOUDS AND
SNOW...HIGH TEMPERATURES WILL STRUGGLE INTO THE TEENS.
FOR FRIDAY...UPPER LEVEL CYCLONIC FLOW WILL CONTINUE THROUGH
FRIDAY...HOWEVER NO PRECIPITATION IS EXPECTED. PLENTY OF
CLOUDINESS IS EXPECTED FRIDAY MORNING...BUT WITH DRIER AIR MOVING
IN FROM THE WEST...NORTHEAST WYOMING AND SOUTHWESTERN SOUTH DAKOTA
MAY SEE SOME SUNSHINE BEFORE THE END OF THE DAY. HIGHS WILL BE IN
THE UPPER TEENS TO MID 20S.
EXTENDED...LONG WAVE TROF OVER THE GREAT LAKES AND UPPER RIDGE OVER
NORTHERN PLAINS WILL GIVE THE FORECAST AREA WARMER TEMPERATURES FOR
THE WEEKEND...WITH HIGHS NEAR NORMAL. AS RIDGE SHIFTS TO THE
EAST...NEXT TROF DEEPENS ACROSS THE WESTERN US...WITH CUT-OFF LOW
OVER THE SOUTHWESTERN US AND NORTHWEST FLOW OVER NORTHERN PLAINS
THROUGH MIDWEEK. DIFFERENCES IN MODEL TIMING OF SEVERAL SHORT WAVES
RESULTS IN LOW POPS...BUT WOULD EXPECT OCCASIONAL CHANCES OF PRECIP
TO INCREASE IN THE SHORT TERM. ARCTIC AIR PROGGED TO REMAIN NORTH
AND EAST OF THE FORECAST AREA...SO WILL MAINTAIN GRADUAL WARMING
TREND.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&
$$
SHORT TERM...WFO UNR
LONG TERM....WFO UNR
AVIATION...CARPENTER
AREA FORECAST DISCUSSION
NWS MEMPHIS TN
1003 PM CST WED DEC 26 2012
.UPDATE...EVENING UPDATE.
&&
.DISCUSSION...
VERY COLD TONIGHT WITH SOME FREEZING FOG POSSIBLE.CLEAR SKIES
ACROSS PORTIONS OF EAST ARKANSAS ARE ALLOWING TEMPERATURES TO
PLUMMET WITH LESS DRAMATIC COOLING ACROSS WEST TENNESSEE...THE
MISSOURI BOOTHEEL AND NORTH MISSISSIPPI. TEMPERATURES IN NORTHEAST
ARKANSAS ARE ALREADY IN THE LOW TO MIDDLE TEENS. DEW POINTS ARE
GENERALLY IN THE UPPER TEENS TO LOWER 20S. SOME FREEZING FOG HAS
ALREADY BEEN OBSERVED AT JBR. WILL HAVE TO MONITOR FOG CLOSELY TO
DETERMINE IF AN ADVISORY IS NEEDED. OTHERWISE THE FORECAST LOOKS
GOOD. MORNING LOWS WILL RANGE FROM THE MIDDLE TEENS TO MIDDLE 20S.
&&
.PREV DISCUSSION... /ISSUED 513 PM CST WED DEC 26 2012/
DISCUSSION... /ISSUED 346 PM CST WED DEC 26 2012/
SEVERAL FORECAST CHALLENGES OVER THE NEXT WEEK. WITH THE LATE
CHRISTMAS NIGHT SHOW STORM WELL OFF TO THE EAST...LOW CLOUDS
LINGERED EAST OF THE MS RIVER. NOCTURNAL POST FRONTAL COOL SEASON
STRATUS OFTEN IS MORE PERSISTENT THAN THE MODELS SUGGEST...AND
HAVE DELAYED THE CLEARING BY A FAIR AMOUNT TONIGHT. SKIES WILL
MORE LIKELY REMAIN CLEAR WHERE HEAVY SNOW OCCURRED LAST NIGHT...
LEADING TO PRIME RADIATIONAL COOLING CONDITIONS AND AN OUTSIDE
CHANCE OF FREEZING FOG TOWARD SUNRISE.
THURSDAY WILL SEE MODIFIED ARCTIC SURFACE HIGH PRESSURE OVER THE
MIDSOUTH...UNDER FAST SOUTH/SOUTHWEST FLOW FLOW ALOFT. THE MODELS
ARE CONSISTENT IN BRINGING A LOW AMPLITUDE SOUTHERN BRANCH
SHORTWAVE INTO THE ARKLAMISS REGION FRIDAY EVENING. ELEVATED
SHOWERS WILL DEVELOP IN THE WARM ADVECTION AND ISENTROPIC LIFT
REGION IN ADVANCE OF THE SHORTWAVE EARLY FRIDAY. NAM SOUNDINGS
POINT TO ALL LIQUID PRECIP ACROSS THE MIDSOUTH FRIDAY MORNING...
BUT SUSPECT THE NAM BOUNDARY LAYER TEMPS MAY BE TOO WARM GIVEN THE
RESIDUAL SNOWPACK. THERE IS THUS AN OUTSIDE CHANCE OF LIGHT
FREEZING RAIN NORTH OF I40 AND MAINLY WEST OF THE MS RIVER FRIDAY
MORNING...BEFORE CHANGING TO RAIN TOWARD MIDDAY FRIDAY.
FOLLOWING ANOTHER COLD FRONTAL PASSAGE SATURDAY... SUNDAY SHOULD
SEE LOW AMPLITUDE RIDGING ALOFT AND FAIR WEATHER ACROSS THE MIDSOUTH.
12Z GFS AND ECMWF MODELS CONTINUE TO SHOW SIGNIFICANT DISAGREEMENT
BEYOND MONDAY... MAKING THE EXTENDED FORECAST PERIODS A CHALLENGE.
OF THE ECMWF...GFS AND CMC MODELS...THE ECMWF APPEARS TO BE A
APPROXIMATE COMPROMISE BETWEEN THE PROGRESSIVE GFS AND THE MUCH
SLOWER CMC MODEL. WITH THE ECMWF ALSO EXHIBITING BETTER RUN TO
RUN CONSISTENCY... HAVE BASED THE MONDAY THROUGH WEDNESDAY PERIODS
ALMOST ENTIRELY ON THE ECMWF. THIS WOULD SUGGEST ANY SIGNIFICANT
PRECIPITATION WOULD HOLD OFF UNTIL MID TO LATE NEXT WEEK..UNTIL A
GREAT BASIN REX BLOCK FINALLY BREAKS DOWN...SENDING SOUTHERN
BRANCH UPPER LEVEL ENERGY TOWARD THE LOWER MS RIVER VALLEY.
PWB
AVIATION...
00Z TAF SET
LOW CLOUDS SEEM TO BE HOLDING TIGHT ACROSS THE MIDSOUTH. CLEARING
LINE HAS MOVED LITTLE OVER THE LAST HOUR. LATEST RUC CLEARS OUT
KMEM FOR A COUPLE OF HOURS BEFORE BRINGING MVFR CIGS BACK IN.
BEGINNING TO WONDER IF KMEM WILL CLEAR AT ALL. WILL MAKE LAST
MINUTE ADJUSTMENT TO TAF BASED ON SATELLITE BUT RIGHT NOW LEANING
TOWARD GOING SCT AT 2000 FT AND THEN INTRODUCING A TEMPO GROUP
BETWEEN 5 AND 9Z FOR BKN MVFR CIGS. KMKL AND KTUP WILL STAY SOCKED
IN THROUGH AT LEAST 12-17Z. KJBR IS CLEAR NOW BUT EITHER FOG...LOW
CLOUDS OR MAYBE BOTH WILL BRING CONDITIONS BACK TO MVFR AFTER 6Z.
WINDS CONTINUE TO DIE DOWN. EXPECT LIGHT WINDS OVER THE NEXT 24
HOURS DUE TO THE HIGH BUILDING INTO THE AREA.
KRM
&&
.AVIATION...
&&
.PRELIMINARY POINT TEMPS/POPS...
MEM 24 39 32 43 / 0 0 10 70
MKL 19 37 27 44 / 10 0 10 60
JBR 15 33 25 36 / 0 0 10 50
TUP 24 45 31 52 / 0 0 10 90
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
MO...NONE.
MS...NONE.
TN...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
400 AM CST THU DEC 27 2012
.SHORT TERM...
TODAY-FORECAST CONFIDENCE HIGH
SECONDARY LOW OFF SOUTHERN NEW ENGLAND TAKING OVER ON EAST COAST
STORM AND FLOW OVER LAKE MICHIGAN TURNING MORE NORTHERLY WITH TIME.
WEAK LAKE EFFECT BAND RIGHT ALONG THE RACINE/KENOSHA SHORE HAS YET
TO TRIGGER A FLURRY AT THE KRAC OBSERVATION...AND SEEMS TO BE
SHIFTING OFFSHORE. 4KM MODELS SEEM TO HAVE A BIT OF A STRONG BIAS
ON THIS FEATURE AND HAVE IT TOO FAR WEST.
LATEST LOCAL WSWRF AND HRRR ARE NOT TOO IMPRESSIVE WITH THIS FEATURE
AND KEEP IT MOSTLY OFFSHORE. IT SHOULD BE NOTED THAT THE MODELS
TURN THE FLOW IN THE LOWEST 1-2KM MORE AND MORE NORTHERLY AND
ACTUALLY INCREASE 850 MB TEMPS A BIT THIS MORNING...DECREASING THE
LAKE INSTABILITY AND DELTA TS A BIT FROM ROUGHLY 15 TO ABOUT 13.
THE LAKE EFFECT STRUGGLED THROUGHOUT THE EVENT DUE TO RELATIVELY DRY
AIR IN 850 TO 700 MB LAYER AND A LOW INVERSION HEIGHT THAT WAS OFTEN
DOWN TO 4000 FEET. WILL KEEP SOME LOW POPS NEAR THE KENOSHA/RACINE
LAKE SHORE BUT DONT EXPECT MUCH TO HAPPEN.
OTHERWISE EXPECT THE GRADIENT TO WEAKEN TODAY WITH WEAK SURFACE
RIDGE MOVING OVER WISCONSIN. STRATUS STATUS APPEARS TO BE PRIMARY
MESSAGE...AS FOG PRODUCT SHOWS A WESTWARD TREND IN LOW CLOUDS. THIS
IS OPPOSED TO THE TREND THAT I FORECAST LAST NIGHT...WHICH SHOULD
NOT BE SURPRISING FOR THOSE WHO KNOW ME.
PER COORDINATION WITH SURROUNDING OFFICES...WENT WITH MUCH CLOUDIER
FORECAST TODAY AS TIME SECTIONS INDICATE LOW CLOUDS WILL BE TOUGH TO
SCOUR OUT TODAY WITH WEAK FORCING AND DECREASING GRADIENT.
TONIGHT-FORECAST CONFIDENCE HIGH
SATELLITE SHOWS IMPRESSIVE VORTICITY MAXIMUM EMERGING ON THE HIGH
PLAINS IN WESTERN NEBRASKA CURRENTLY. MODELS IN GOOD AGREEMENT IN
MOVING 500 MB CLOSED LOW TO NORTH CENTRAL NEBRASKA THIS AFTERNOON
AND THEN CLOSE TO THE SD/IA/NE BORDER AREA NEAR SIOUX CITY TONIGHT.
WEAK BUT DEEP WARM ADVECTION EXPECTED AHEAD OF THIS FEATURE AND
SHOULD SPREAD ACROSS IOWA TOWARD WISCONSIN LATE TONIGHT. DESPITE
FAIRLY WEAK LIFT THERE IS A RATHER DEEP AND NEARLY SATURATED LAYER
IN THE DENDRITE GROWTH ZONE (-12 TO -18C) WITH THIS SYSTEM WHICH
WOULD ENHANCE SNOW POTENTIAL AND ESPECIALLY SNOW TO LIQUID RATIOS.
THEREFORE WENT WAY ABOVE GUIDANCE IN THE WEST LATE TONIGHT...WHICH
IS SURPRISINGLY LOW GIVEN CONSISTENT HANDLING OF THIS FEATURE BY
GUIDANCE. APPEARS THAT MOS IS LEANING TOWARD THE TENDENCY FOR ASOS
TO STRUGGLE TO MEASURE LIGHT SNOWFALL IN EVENTS LIKE THIS.
FRIDAY AND FRIDAY NIGHT...FORECAST CONFIDENCE HIGH.
SNOW WILL OVERSPREAD ALL OF SOUTHERN WI FRI MORNING AND TAPER OFF
FROM WEST TO EAST FRIDAY EVENING. STORM TOTAL SNOW AMOUNTS FROM LATE
THU NIGHT THROUGH FRIDAY EVENING SHOULD BE IN THE 2 TO 4 INCH
RANGE...POSSIBLY HIGHER FROM THE DELLS TO MADISON TO RACINE AND THE
OTHER LAKESHORE COUNTIES IF LAKE ENHANCEMENT OCCURS. MAJORITY OF THE
SNOW SHOULD FALL IN AN 8-HOUR PERIOD ON FRIDAY...AFFECTING THE
MORNING RUSH IN MADISON AND THE EVENING RUSH IN BOTH MADISON AND
MILWAUKEE. A LOW-END WINTER WEATHER ADVISORY WILL NEED TO BE
CONSIDERED...BUT WILL HIGHLIGHT THE RUSH HOUR HEADACHE WITH A
SPECIAL WEATHER STATEMENT FOR NOW.
OVERALL THE SYSTEM DYNAMICS ARE NOT OVERLY IMPRESSIVE...BUT THE
SLOW-MOVING NATURE OF THE UPPER TROUGH AND THE SUBTLE AND PERSISTENT
FORCING WILL BE ENOUGH TO PRODUCE SEVERAL INCHES OF FLUFFY SNOW OVER
ROUGHLY AN 18-HR PERIOD. WINDS WILL BE LIGHT OUT OF THE EAST ON
FRIDAY. THE STRONGEST FORCING WILL BE ASSOCIATED WITH A VORT MAX
ROLLING ACROSS IOWA AND SOUTHERN WI FRI. BEST OMEGA VALUES WILL
GENERALLY BE JUST BELOW THE DENDRITIC GROWTH ZONE /DGZ/ FOR MOST OF
THE PERIOD. HOWEVER... THE DGZ WILL BE FAIRLY DEEP AT AROUND 5K TO
7K FT. THERE SHOULD BE AT LEAST A FEW-HOUR PERIOD OF TIME WHERE
THERE IS DECENT OMEGA WITHIN THE DEEP DGZ LEADING TO EFFICIENT SNOW
ACCUMULATION. THE NAM SHOWS THIS OCCURRING AROUND 18Z AT MSN AND 20Z
AT MKE.
SEVERAL OF THE MESOSCALE MODELS ARE SHOWING A MID-LAKE LAKE EFFECT
BAND MOVE ONSHORE WITH THE EASTERLY WINDS...WITH A FEW OF THEM
DEVELOPING A MESO-LOW OVER SOUTHERN LAKE MICHIGAN. AS A
RESULT...THESE MODELS SEEM TO BE OVER-DOING THE QPF AND SNOW AMOUNTS
NEAR THE LAKESHORE. BUT IT NEEDS TO BE NOTED THAT SOME SUBTLE LAKE
ENHANCEMENT WILL BE POSSIBLE WITH THE 13C-18C DELTA T FOR THE
LAKESHORE COUNTIES.
SATURDAY...FORECAST CONFIDENCE MEDIUM.
THE UPPER TROUGH WILL STILL BE OVER THE GREAT LAKES REGION AND THE
LOW LEVEL MOISTURE WILL LINGER SO KEPT MENTION OF FLURRIES THROUGH
THE DAY AND CLOUDS THROUGH THE DAY AND NIGHT. WEAK COLD AIR
ADVECTION DURING THIS TIME...BUT CLOUD COVER WILL KEEP TEMPS
MODERATED...WITH HIGHS IN THE UPPER 20S.
.LONG TERM...
SUNDAY THROUGH THURSDAY...FORECAST CONFIDENCE...MEDIUM.
SOME SUNSHINE IS EXPECTED ON SUNDAY. LOW PRESSURE WILL TRACK ACROSS
LAKE SUPERIOR SUN NIGHT AND THE ASSOCIATED COLD FRONT WILL CROSS
SOUTHERN WI MON MORNING...USHERING COLDER AIR INTO THE AREA. A
PERIOD OF CLOUDS WILL BE LIKELY WITH THIS FRONTAL PASSAGE.
ANOTHER WEAK WAVE WILL MOVE THROUGH THE UPPER GREAT LAKES AREA WED
MORNING WHICH MAY PRODUCE SOME LIGHT SNOW OR FLURRIES. THE ECMWF IS
DRY AND THE GFS SHOWS VERY LIGHT QPF.
&&
.AVIATION/12Z TAFS/...
TIME HEIGHT SECTIONS FROM BOTH GFS AND NAM NOW SHOW STRATUS
REMAINING IN PLACE IN SOUTHEAST THROUGH TONIGHT. SHOULD BE NO WORSE
THAN MVFR AND LIKELY TO IMPROVE A TAD TO LOWER END VFR CEILINGS
LATER TODAY INTO TONIGHT. MOST UNCERTAINTY IS KMSN...WHERE THE
GUIDANCE SHOWS THE STRATUS DECK VANISHING WITHIN THE NEXT FEW
HOURS.
FOG PRODUCT TRENDS AND SURFACE OBSERVATIONS DO NOT SUPPORT THIS
TREND. THUS...WILL EXTEND THE VFR CEILING A BIT LONGER INTO THE
MIDDAY HOURS BEFORE GOING WITH SCATTERED LOWER DECK.
REGARDLESS OF WHAT HAPPENS TO LOWER DECK EXPECT MID LEVEL CLOUDS TO
MOVE IN QUICKLY AROUND 00Z AND GRADUALLY LOWER WITH A GOOD THREAT
FOR VIRGA/SNOW ALOFT IN THE 06Z TO 12Z PERIOD...ESPECIALLY IN KMSN.
SNOW SHOULD START AROUND 12Z IN KMASN AND THEN SPREAD TO SOUTHEAST
WI STAFFS AROUND 18Z. PROLONGED IFR CONDITIONS LIKELY WITH THE
LIGHT SNOW.
&&
.MARINE...
NORTH TO NORTHWEST WINDS ARE NEAR SMALL CRAFT LEVELS NOW BUT SHOULD
GRADUALLY DIMINISH TODAY. WITH OFFSHORE FLOW THE WAVES ARE ALREADY
DIMINISHING BUT SHOULD REMAIN ABOVE 4 FEET UNTIL LATE AFTERNOON.
PER COORDINATION WITH GRB AND LOT WILL END SMALL CRAFT ADVISORY
ABOUT 9 HOURS EARLIER THAN PREVIOUS FORECASTS...AT 00Z TODAY.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 6 PM CST THIS EVENING FOR LMZ643>646.
&&
$$
TODAY/TONIGHT AND AVIATION/MARINE...MRC
FRIDAY THROUGH WEDNESDAY...CRAVEN
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
209 AM CST THU DEC 27 2012
.SHORT TERM...
209 AM CST THU DEC 27 2012
FORECAST FOCUS PRIMARILY ON SNOW AMOUNTS TONIGHT INTO FRIDAY
AND THE NEED FOR AN ADVISORY.
07Z SURFACE ANALYSIS SHOWS THE HIGH PRESSURE RIDGE RUNNING FROM
WESTERN ONTARIO DOWN THROUGH MN/IA/MO. AIR MASS IS RATHER `DIRTY`
UNDER THE RIDGE...WITH VARIOUS PATCHES OF LOW/MID/HIGH CLOUD.
SATELLITE WATER VAPOR IMAGERY SHOWS THE NEXT CLOSED CIRCULATION
AND LONG WAVE TROUGH MOVING ALONG THE WY/CO BORDER TOWARD THE
NE PANHANDLE. THE CIRCULATION IS ALSO EVIDENT ON THE FOG
ENHANCEMENT IMAGERY NEAR CHEYENNE. LOW CLOUDS WERE ALREADY
DEVELOPING AHEAD OF THIS NEXT SYSTEM AND HAVE REACHED AS FAR
EAST AS NORTHWEST IA. OTHER ITEM OF NOTE IS ALL OF THE STRATUS
ACROSS WI/IL BEHIND THE WINTER STORM MOVING THROUGH THE NORTHEAST.
THE WESTERN EDGE OF THE CLOUD SHIELD HAD BEEN MAKING GOOD WESTWARD
PROGRESS TONIGHT...BUT HAS SLOWED THE LAST FEW HOURS AS IT NEARED
THE RIDGE AXIS.
MODEL SOLUTIONS ARE IN GOOD AGREEMENT IN TRACKING THE DISTURBANCE
ACROSS NE TODAY AND THROUGH NORTHERN IA LATE TONIGHT AND FRIDAY.
AIR MASS IN PLACE OVER OUR REGION IS VERY COLD...AND THIS WILL HELP
THE SYSTEM TO MAKE GOOD USE OF WHATEVER MOISTURE IT HAS. ALSO...
THE SLOW MOVEMENT AND STORM TRACK WILL KEEP THE FORECAST AREA IN
THE BEST POSITION FOR A LONGER DURATION OF SNOWFALL STARTING LATE
TODAY AND PERSISTING WELL INTO THE DAYLIGHT HOURS ON FRIDAY. MODEL
SOUNDINGS INDICATE THERE WILL BE SOME DRY AIR TO OVERCOME AS THE
SNOW BEGINS...BUT FEEL THIS IS OVERDONE. MODELS HAVE BEEN HAVING A
TERRIBLE TIME WITH THE LOW CLOUDS/MOISTURE OF LATE...AND DO NOT
FEEL IT WILL SLOW DOWN THE SNOW TOO MUCH. SO...EXPECTING A
PROTRACTED 18-24 HOUR PERIOD OF LIGHT SNOW...AND WITH THE COOL
TEMPS PROVIDING RATIOS AROUND 15:1 OR PERHAPS AS HIGH AS
18:1...EXPECT A GENERAL 1-3 INCHES OF SNOW...WITH A FEW SPOTS
PERHAPS SEEING 4 INCHES. WITH THESE AMOUNTS WAS CONSIDERING THE
NEED FOR A WINTER WEATHER ADVISORY FOR LOCATIONS MAINLY ALONG AND
SOUTH OF INTERSTATE 90. BUT THE FACT THAT THE SNOW DOES NOT APPEAR
TO BE FALLING AT A HIGH RATE FOR ANY LENGTH OF TIME LEADS ME TO
HOLD OFF ON THE ADVISORY AT THIS POINT. WILL OPT INSTEAD TO
ENHANCE THE WORDING IN THE HAZARDOUS OUTLOOK AND ISSUE A SPECIAL
WEATHER STATEMENT.
THE DISTURBANCE EXITS THE AREA LATE FRIDAY...BUT A FEW WEAKER
SHORT WAVE TROUGHS LOOK TO DROP INTO THE BACK SIDE OF THE MAIN
UPPER LONG WAVE TROUGH...AND THESE WILL CROSS OUR AREA ON
SATURDAY. THIS COULD RESULT IN SOME SCATTERED FLURRIES...SO WILL
LEAVE MENTION IN THE FORECAST PER YESTERDAY.
.LONG TERM...
209 AM CST THU DEC 27 2012
THE LATEST MEDIUM RANGE MODELS CONTINUE TO POINT TO A PROGRESSIVE
WEATHER PATTERN INTO EARLY NEXT WEEK. BEHIND OUR DEPARTING
TROUGH A BRIEF PERIOD OF RIDGING WILL PREVAIL ON SUNDAY...ONLY TO
BE REPLACED BY ANOTHER TROUGH MOVING FROM SASKATCHEWAN DOWN
INTO LAKE SUPERIOR BY MONDAY. THE MAIN FORCING AND MOISTURE FROM
THIS SYSTEM LOOK TO REMAIN TOO FAR NORTH FOR ANY SNOW IN OUR AREA.
MEANWHILE A LARGER LONG WAVE TROUGH SETS UP ALONG THE WEST COAST.
THE MODELS CONTINUE TO STRUGGLE WITH HOW TO EVOLVE THIS FEATURE...
ALTHOUGH THEY ARE BEGINNING TO CONVERGE SOMEWHAT. ONE CAMP OF
MODEL SOLUTIONS LED BY THE ECMWF KEEP A SLOW-MOVING CLOSED
CIRCULATION OVER AZ/NM TUE INTO WED...WHILE ANOTHER GROUP OF
SOLUTIONS KEEP THE TROUGH OPEN AND MOVE IT EAST THROUGH THE
SOUTHERN PLAINS BY MID-WEEK. EITHER WAY...THE BULK OF THAT FEATURE
LOOKS TO REMAIN WELL SOUTH OF THE FORECAST AREA. OUR WEATHER WILL
COME FROM THE NORTHWEST FLOW REGIME OVER THE UPPER MIDWEST AND
GREAT LAKES REGION. THE NEXT DISTURBANCE LOOKS TO ARRIVE LATE
TUESDAY INTO WEDNESDAY. BUT ONCE AGAIN...THE BULK OF THE MOISTURE
AND SUPPORT LOOK TO PASS TO THE NORTH. THE OVERALL EVOLUTION OF
THE SOUTHERN STREAM MAY ALTER THIS SLIGHTLY...SO WILL NEED TO
MONITOR. BUT MEANWHILE...ANTICIPATE COOL AND MAINLY SNOW FREE
CONDITIONS TO PREVAIL.
&&
.AVIATION...THROUGH 06Z FRIDAY
1119 PM CST WED DEC 26 2012
LARGE AREA OF MVFR STRATUS CLOUDS OVER EASTERN WISCONSIN HAS BEEN
WORKING STEADILY WEST THIS EVENING. NONE OF THE MODELS HAVE A REAL
GOOD HANDLE ON THIS CLOUD FIELD BUT THE 27.03Z RAP AT LEAST HAS AN
IDEA IT IS THERE. GIVEN THE CURRENT MOVEMENT OF THE CLOUD
FIELD...THE RAP LOOKS TO BE TOO SLOW MOVING THE CLOUDS WEST...BUT
IT DOES INDICATE THAT THE CLOUDS SHOULD MAKE IT INTO BOTH TAF
SITES. HAVE ALREADY UPDATED THE KLSE TAF TO BRING THESE CLOUDS IN
AND WILL SHOW THEM ARRIVING IN KRST BEFORE 12Z. THE RAP WOULD
SUGGEST THAT ONCE THE CLOUDS ARE IN PLACE THEY SHOULD REMAIN
THROUGH THURSDAY AND WILL SHOW THIS TREND. THE FORCING FROM THE
SHORT WAVE TROUGH MOVING OUT OF THE CENTRAL ROCKIES WILL START TO
MOVE IN EARLY THURSDAY EVENING. THE MVFR CLOUD DECK WILL HELP TO
AID IN THE LOW LEVEL SATURATION SO EXPECT THIS WAVE TO BE ABLE TO
START PRODUCING LIGHT SNOW FAIRLY QUICKLY. WILL SHOW THE LIGHT
SNOW AT KRST STARTING AT 28.00Z WITH THE VISIBILITY GOING DOWN TO
IFR IN THE SNOW BY THE MIDDLE OF THE EVENING. WILL BRING THE LIGHT
SNOW IN KLSE BY THE MIDDLE OF THE EVENING AND WILL HOLD ONTO A VFR
VISIBILITY BUT COULD SEE THIS GO DOWN TO MVFR OR IFR BEFORE 28.06Z.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
209 AM CST THU DEC 27 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...MW
LONG TERM...MW
AVIATION...04
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1119 PM CST WED DEC 26 2012
.SHORT TERM...TODAY THROUGH SATURDAY
315 PM CST WED DEC 26 2012
MAIN FORECAST CONCERNS ARE ON SNOW ACCUMULATIONS THURSDAY NIGHT
THROUGH FRIDAY.
LATEST WATER VAPOR IMAGERY SHOWED A VIGOROUS UPPER LOW LIFTING
NORTHEAST THROUGH THE MID APPALACHIANS. A SHORTWAVE WAS MOVING
ACROSS CENTRAL CALIFORNIA HEADING EAST TOWARDS THE CENTRAL ROCKIES.
SURFACE OBSERVATIONS SHOWED HIGH PRESSURE CENTERED OVER SOUTHEAST
MANITOBA WITH THE RIDGE AXIS EXTENDING SOUTH THROUGH THE UPPER
MISSISSIPPI RIVE VALLEY. THE PRESSURE GRADIENT WAS TIGHTENING ACROSS
SOUTHEAST WISCONSIN AS THE VIGOROUS LOW MOVES THROUGH THE
APPALACHIANS.
THE HIGH WILL REMAIN IN CONTROL TONIGHT THROUGH THURSDAY MORNING
PROVIDING QUIET WEATHER. LOW TEMPERATURES TONIGHT WILL BE A LITTLE
TRICKY WITH THE CLOUDS STREAMING IN FROM THE SOUTHEAST. LOW
TEMPERATURES TONIGHT ARE EXPECTED TO FALL INTO THE SINGLE
DIGITS...WITH FAVORED COLD SPOTS SUCH AS BLACK RIVER
FALLS...SPARTA...AND DIAMOND LAKE FALLING INTO THE SINGLE DIGITS
BELOW ZERO. IF CLOUDS HOLD ON ACROSS CENTRAL INTO FAR SOUTHWEST
WISCONSIN HIGHS COULD POSSIBLY END UP A FEW DEGREES WARMER THAN
FORECAST. CLOUDS WILL BE ON THE INCREASE ACROSS THE AREA ON
THURSDAY AS THE SHORTWAVE EJECTS OUT OF THE CENTRAL ROCKIES AND
MOVES ACROSS SOUTH DAKOTA AND NEBRASKA. PLAN ON HIGHS ON THURSDAY
RANGING FROM LOWER 20S OVER NORTH CENTRAL WISCONSIN TO THE MID 20S
OVER FAR SOUTHWEST WISCONSIN INTO NORTHEAST IOWA.
THE SHORTWAVE IS EXPECTED TO TRACK ACROSS SOUTHERN
MINNESOTA/NORTHERN IOWA THURSDAY NIGHT AND EAST INTO SOUTHERN
WISCONSIN/NORTHERN ILLINOIS EARLY FRIDAY MORNING INTO FRIDAY
AFTERNOON. ISENTROPIC LIFT INCREASES ACROSS THE FORECAST AREA LATE
THURSDAY AFTERNOON INTO THURSDAY EVENING...ON THE 280-305 K
SURFACES. ALSO...MODEST FRONTOGENESIS...ON THE 700-500MB LAYER
INCREASES ACROSS NORTHEAST IOWA AND FAR SOUTHEAST WISCONSIN THURSDAY
EVENING INTO FRIDAY MORNING. NAM/GFS/ARW ARE ALL SHOWING AN ENHANCED
SNOW BAND ACROSS NORTHEAST IOWA INTO FAR SOUTHWEST WISCONSIN. OMEGA
IN THE DENDRITIC GROWTH ZONE INCREASES INTO THE -4 TO -6.9 UBAR/S
RANGE THURSDAY EVENING THEN CONTINUES OVERNIGHT. IT ALSO APPEARS
THAT THE DENDRITIC GROWTH ZONE WILL BE AROUND 100 TO 150 MB DEEP.
THINKING SNOW RATIOS WILL BE RATHER HIGH...RANGING FROM 15:1 TO
20:1. SNOW WILL DEVELOP ACROSS LOCATIONS WEST OF THE MISSISSIPPI
RIVER EARLY THURSDAY EVENING AND WILL THEN SPREAD EAST OF THE
MISSISSIPPI LATE THURSDAY EVENING INTO THE OVERNIGHT HOURS. AT THIS
TIME 1 TO 3 INCHES LOOKS LIKELY ALONG AND SOUTH OF THE INTERSTATE 90
CORRIDOR BY LATE FRIDAY MORNING. LOCALLY HIGHER AMOUNTS UP TO 4
INCHES ARE POSSIBLE ACROSS NORTHEAST IOWA INTO FAR SOUTHWEST
WISCONSIN WHERE THE STRONGER FRONTOGENESIS BAND WILL BE IN PLACE.
LOCATIONS NORTH OF INTERSTATE 90 CORRIDOR TO AROUND WISCONSIN
HIGHWAY 10 WILL SEE ACCUMULATIONS OF 1 TO 2 INCHES. NORTH OF HIGHWAY
10 PLAN ON SNOWFALL AMOUNTS OF AROUND AN INCH. A WINTER WEATHER
ADVISORY WILL LIKELY BE NEEDED FOR LOCATIONS ALONG AND SOUTH OF THE
INTERSTATE 90 CORRIDOR THURSDAY NIGHT THROUGH EARLY FRIDAY
AFTERNOON.
THE SHORTWAVE WILL PUSH INTO EASTERN WISCONSIN FRIDAY NIGHT BUT LOW
LEVEL MOISTURE WILL LINGER OVER THE FORECAST AREA. A SECONDARY WAVE
WILL IS EXPECTED TO MOVE ACROSS THE REGION SATURDAY NIGHT PRODUCING
FLURRIES OVER MUCH OF THE AREA. THE FLURRIES WILL PERSIST THROUGH
SATURDAY MAINLY EAST OF THE MISSISSIPPI RIVER. PLAN ON LOWS FALLING
INTO THE TEENS FRIDAY NIGHT. LOOK FOR HIGHS ON SATURDAY TO RANGE
FROM THE LOWER 20S OVER SOUTHEAST MINNESOTA TO THE MID TO UPPER 20S
ACROSS CENTRAL WISCONSIN.
.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY
315 PM CST WED DEC 26 2012
26.12 MEDIUM RANGE MODELS ARE IN AGREEMENT SATURDAY NIGHT THROUGH
SUNDAY SHOWING HIGH PRESSURE BUILDING ACROSS THE UPPER MISSISSIPPI
RIVER WITH DRY AND QUIET CONDITIONS EXPECTED. MEANWHILE A TROUGH
WILL DIG INTO THE DESERT SOUTHWEST. A NORTHERN STREAM TROUGH LOOKS TO
DROP SOUTH OUT OF SOUTHERN MANITOBA SASKATCHEWAN SUNDAY NIGHT. THE
TROUGH IS EXPECTED TO MOVE ACROSS LAKE SUPERIOR AND NORTHERN
WISCONSIN ON MONDAY. THE ECMWF AND GFS START TO DIVERGE MONDAY INTO
WEDNESDAY. THE ECMWF CUTS THE LOW OFF OVER THE DESERT SOUTHWEST
WHILE THE GFS IS PROGRESSIVE AND TAKES THE LOW EAST THROUGH THE
SOUTHERN PLAINS. WILL LEAN TOWARD A MODEL CONSENSUS BLEND MONDAY
THROUGH WEDNESDAY. KEEPING A CLOSE WATCH ON THE WAVE MOVING THROUGH
THE AREA ON MONDAY OTHERWISE PLAN ON QUIET CONDITIONS WITH HIGHS IN
THE 20S AND LOWS IN THE SINGLE DIGITS.
&&
.AVIATION...THROUGH 06Z FRIDAY
1119 PM CST WED DEC 26 2012
LARGE AREA OF MVFR STRATUS CLOUDS OVER EASTERN WISCONSIN HAS BEEN
WORKING STEADILY WEST THIS EVENING. NONE OF THE MODELS HAVE A REAL
GOOD HANDLE ON THIS CLOUD FIELD BUT THE 27.03Z RAP AT LEAST HAS AN
IDEA IT IS THERE. GIVEN THE CURRENT MOVEMENT OF THE CLOUD
FIELD...THE RAP LOOKS TO BE TOO SLOW MOVING THE CLOUDS WEST...BUT
IT DOES INDICATE THAT THE CLOUDS SHOULD MAKE IT INTO BOTH TAF
SITES. HAVE ALREADY UPDATED THE KLSE TAF TO BRING THESE CLOUDS IN
AND WILL SHOW THEM ARRIVING IN KRST BEFORE 12Z. THE RAP WOULD
SUGGEST THAT ONCE THE CLOUDS ARE IN PLACE THEY SHOULD REMAIN
THROUGH THURSDAY AND WILL SHOW THIS TREND. THE FORCING FROM THE
SHORT WAVE TROUGH MOVING OUT OF THE CENTRAL ROCKIES WILL START TO
MOVE IN EARLY THURSDAY EVENING. THE MVFR CLOUD DECK WILL HELP TO
AID IN THE LOW LEVEL SATURATION SO EXPECT THIS WAVE TO BE ABLE TO
START PRODUCING LIGHT SNOW FAIRLY QUICKLY. WILL SHOW THE LIGHT
SNOW AT KRST STARTING AT 28.00Z WITH THE VISIBILITY GOING DOWN TO
IFR IN THE SNOW BY THE MIDDLE OF THE EVENING. WILL BRING THE LIGHT
SNOW IN KLSE BY THE MIDDLE OF THE EVENING AND WILL HOLD ONTO A VFR
VISIBILITY BUT COULD SEE THIS GO DOWN TO MVFR OR IFR BEFORE 28.06Z.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
315 PM CST WED DEC 26 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION...04
AREA FORECAST DISCUSSION
NWS ALBANY NY
804 AM EST THU DEC 27 2012
.SYNOPSIS...
A WINTER STORM WILL PASS SOUTH OF LONG ISLAND TODAY AND INTO THE
GULF OF MAINE TONIGHT. WEAK HIGH PRESSURE WILL BUILD INTO THE
REGION FOR FRIDAY. SATURDAY ANOTHER LOW WILL ORGANIZE ALONG THE
CAROLINA COAST...AND MOVE NORTHEAST INTO THE ATLANTIC. IT WILL
BRING THE THREAT OF SOME LIGHT SNOW. COLDER AIR WILL SURGE INTO
THE REGION TO END THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 8 AM...
MESOSCALE BANDING FEATURES ARE BECOMING MORE APPARENT PER THE
LATEST SCANS OF THE RADAR AND THE RUC13 LOW LEVEL CONVERGENCE
FIELDS SHOW AN INCREASING ACROSS THE HUDSON RIVER VALLEY. THIS
WILL ENHANCE THE SNOWFALL RATES THIS MORNING. FURTHERMORE...PER
CSTAR RESEARCH...MOHAWK VALLEY CONVERGENCE MAY ALSO CONTRIBUTE TO
ENHANCED LIFT WITHIN THE CAPITAL REGION. 989MB SURFACE LOW WAS
JUST SOUTH OF LONG ISLAND AS THIS IS A FAVORED TRACK FOR MODERATE
TO HEAVY PRECIPITATION WITH ENHANCED CONVERGENCE ACROSS THE HUDSON
RIVER VALLEY. WE WILL CONTINUE TO MONITOR CLOSELY.
PER DUAL POL RADAR DATA...THERE APPEARS TO BE A MIX
DEVELOPING/ONGOING ACROSS THE BERKSHIRES AND LITCHFIELD COUNTY.
THIS WILL HAVE AN IMPACT ON SNOW ACCUMULATIONS AS WELL...
PREV DISC..
...MAJOR WINTER STORM CONTINUES TO IMPACT EASTERN NEW YORK AND
WESTERN NEW ENGLAND...
AS OF 630 AM EST...SNOWFALL HAS BECOME QUITE PATCHY...WITH LARGE
AREAS WITHIN THE IMMEDIATE HUDSON VALLEY AND TACONICS EXPERIENCING
VERY LIGHT PRECIPITATION. ANOTHER MORE ORGANIZED BAND OF MODERATE
TO LOCALLY HEAVY PRECIPITATION IS NOW PIVOTING NORTHWEST FROM THE
MID HUDSON VALLEY...NW CT AND SOUTHERN BERKSHIRE CO. THIS BAND
WILL LIKELY CONTINUE SLOWLY ADVANCING NORTHWEST...AND MAY TAKE ON
A MORE NORTH-SOUTH ORIENTATION SHORTLY AFTER SUNRISE THROUGH MID
MORNING. WE WILL HAVE TO WATCH FOR THIS IN CASE IT STALLS...AND
PRODUCES LOCALLY HEAVY SNOWFALL ONCE AGAIN WITHIN THE HUDSON RIVER
VALLEY. WE DO EXPECT ANOTHER 3-6 INCHES IN MOST AREAS FROM THE
CAPITAL REGION NORTH AND WEST...AS WELL AS INTO THE BERKSHIRES AND
SOUTHERN GREENS...AND EASTERN CATSKILLS/HELDERBERGS...WITH LOCALLY
HIGHER AMTS POSSIBLE...ESP ACROSS HIGHER ELEVATIONS. FURTHER SOUTH
AND EAST...ACROSS THE SOUTHERN BERKSHIRES...TACONICS...NW CT...AND
MID HUDSON VALLEY REGION...A FEW MORE BURSTS OF MIXED
PRECIPITATION...SOME SNOW...SLEET AND FREEZING RAIN...WILL OCCUR
OVER THE NEXT 3 HOURS...BEFORE GRADUALLY TAPERING OFF. IN THESE
AREAS...AN ADDITIONAL COATING TO ONE TENTH OF AN INCH OF ICE
ACCRETION...ALONG WITH UP TO AN INCH OF SNOWFALL IS POSSIBLE.
NOON THROUGH SUNSET...THE DEFORMATION AREA SHOULD CONTINUE
TRANSLATING EASTWARD INTO NEW ENGLAND. HOWEVER...THERE IS A
POSSIBILITY THAT HUDSON-MOHAWK CONVERGENCE...WHICH IS LOW LEVEL
CONVERGENCE THAT OCCURS IN THE WAKE OF DEPARTING COASTAL LOWS FROM
THE COMBINATION OF A DEVELOPING WEST/NORTHWEST WIND DOWN THE
MOHAWK VALLEY...AND A LINGERING N/NE FLOW DOWN THE HUDSON RIVER
VALLEY...MAY LEAD TO ANOTHER 1-2 INCHES OF SNOWFALL IN THE
IMMEDIATE CAPITAL REGION.
OTHERWISE...FOR TEMPS...HAVE GONE COOLER THAN BOTH THE MAV AND MET
MOS...WITH MAXES ONLY REACHING 30-35 IN VALLEY REGIONS...WITH 20S
ACROSS HIGHER ELEVATIONS. IT WILL BE WARMER INITIALLY ACROSS S/E
AREAS THIS MORNING...FROM PORTIONS OF WESTERN MA INTO NW CT AND
THE MID HUDSON VALLEY...WITH TEMPS POSSIBLY FALLING THEREAFTER.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
DEPARTING STORM IS VERTICALLY STACKED AND LIFTING ENE INTO GULF
OF MAINE TNGT. BRISK N GRADIENT WILL GRADUALLY DIMINISH OVRNT.
RESIDUAL LLVL MOISTURE WILL KEEP -SHSN GOING MAINLY N...BUT WITH
LITTLE ADDITIONAL ACCUMULATION.
FRIDAY 500HPA RIDGE BUILDS ACROSS RGN ALONG WITH WK SFC HIGH. WITH
WK FLOW CONSIDERABLE LLVL MOISTURE AND LOW SUN ANGLE AND INVERSION
DEGREE OF SUN WILL BE IN QUESTION. MET IS MC AND MAV PS. IN ANY
CASE FRI WILL BE A SHORT REPRIEVE WITH NR NORMAL TEMPS.
FRIDAY NIGHT THE RIDGE AT 500HPA AND SFC SLIDES OFFSHORE AND 500HPA
TROF MOVES EAST INTO MIDWEST AND GRTLKS. IN RESPONSE SFC LOW PRESSURE
ORGANIZES ALONG THE CAROLINA COAST. THERE REMAINS SOME SPREAD IN
HOW THE MODELS DEVELOP THIS TROF. THE NAM IS FLAT...THE GEM THE
SHARPEST THE GFS BTWN THEM. THE ECMWF IS SIMILAR TO GFS...BUT HAS
SFC LOW BOMBING CLOSER TO THE COAST. THE END RESULT IS DIFFERENCES
IN THE EVOLVING WX SYSTEMS. THE NAM RESULTS IN A RATHER NON
DISCRIPT SOLUTION WITH BULK OF IMPACTS OF THE TROF PASSING SOUTH
OF RGN AS IT NEVER REALLY ORGANIZES. THE GEM/GFS/ECMWF DVLP A COASTAL
LOW THAT ALONG WITH THE 500 HPA TROF DEVELOP A WIDESPREAD AREA OF
OVERRUNNING LT SNOW DURING THE DAY SAT. WITH HALF THE GFS ENSEMBLE
MEMBERS SUPPORTING THE COUPLE OF TENTHS OF QPF AND LT SNOW...WILL
POPULATE WITH PERIOD WITH GMOS. THIS EVENT HAS BEEN SUBJECT TO
CONSIDERABLE SPREAD OVER THE PAST FEW DAYS...AND THIS CONTINUES.
THE MAIN CHANGE IS THE SIGNAL THAT SOMETHING WILL HAPPEN IS
STRONGER.
THIS SFC LOW PASSES WELL SOUTH OF RGN SO PTYPE IS NOT A CONCERN IT
WILL BE SNOW WHERE IT PRECIPITATES. AMOUNTS WILL BE GREATER
SOUTH...BUT AT THIS TIME THIS EVENT WILL BE A FEW INCHES OF SNOW AT
MOST AND SUB FLAG LEVEL. SAT NT THE SFC LOW WILL DEPART...BUT THE
500 HPA TROF WILL LINGER ALONG THE SEABOARD. THE COMBINATION WILL
ALLOW COLDER AIR OVER ONTARIO AND QUEBEC TO BE DRAWN S INTO FCA AS
SFC GRADIENT STRENGTHEN IN WAKE OF DEPARTING STORM.
CAA...RESIDUAL LLVL MOISTURE...TRRN AND AND SOME FORCING FROM TROF
ALOFT WILL KEEP THREAT OF -SHSN MAINLY N & W OF ALB SAT NT. SFC
FLOW FM N WILL MINIMIZE IMPACT OF LKS IN THIS. WHILE MAIN SFC HIGH
WILL BE OVER THE MISS/OHIO VLYS SUNDAY A SECONDARY COLDER CORE SFC
HIGH WILL BE OVER ONT WITH WK CDFNT DRAPED INTO RGN SUNDAY. SUNDAY
WILL BE A COLD DAY WITH BLO NORMAL TEMPS LOWS SINGLE DIGITS TO
TEENS HIGHS 20S. WITH MILDER AIR MASS OVER SE USA AND COLD AIR
MASS OVER S TIER OF CANADA...A 170KT 250HPA JET WILL DEVELOP FM
GRTKLS INTO MID ATLC STATES.
&&
.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
THERE CONTINUES TO BE SPREAD AS TO HOW COLD THIS PERIOD WILL BE
THE PAST FEW RUNS. THE GFS IS MILDER THAN THE REST OF THE GUID
SUITE. HWVR THE SOLUTIONS ARE CONVERGING FM PAST FEW DAYS.
COASTAL LOW DEPARTS SUNDAY NIGHT WITH ANOTHER WEAK SFC HIGH
PRESSURE AREA CRESTING OVR RGN MON. MON NT AND EARLY TUES YET
ANOTHER 500HPA TROF PUSHES ACROSS THE RGN DRAGGING AN ARCTIC CDFNT
THROUGH FCA. PASSAGE EITHER MON NT AND TUES....FOLLOWED BY ANOTHER
BURST OF CAA. AGAIN THIS PERIOD FEATURES MAINLY N-NNW WINDS...SO
SCT -SHSN WILL BE RESULT OF 500HPA TROF...LLVL MOISTURE AND
FOCUSED ALONG CDFNT. LKS WILL AGAIN NOT BE MUCH IN THE PICTURE
FOR OUR FCA. DETAILS GET KINDA MUDDIED BYND MONDAY...BUT IT WILL
BE A COLD...VRBL CLOUDS WITH SCT-BKN -SHSN. TEMPS WILL BE BLO
NORMAL MON AND FALLING OFF THE CLIFF THRU THE PERIOD TO 10-15 DEG
BLO NORMALS. WILL POPULATE WITH HPC MIDNIGHT GRIDS. THE GFS
CONTINUES TO BE THE MILDER OF THE MODELS FOR THIS PERIOD BUT WITH
BOTH THE ECMWF/GEM AND HPC FAVORING A COLDER SOLUTION WILL ELAN
TWRD THAT AND MAINTAIN CONSISTENCY WITH CURRENT FCST.
&&
.AVIATION /13Z THURSDAY THROUGH MONDAY/...
DESPITE THE RELATIVE STRENGTH OF THE SURFACE LOW MOVING OFF THE MID
ATLANTIC COAST...THE PCPN SHIELD ASSOCIATED WITH THIS LOW HAS NOT
BEEN VERY UNIFORM WITH CONDITIONS RANGING FROM AREAS OF HEAVY SNOW
TO LITTLE OR NO PCPN FALLING DURING THE NIGHT. THIS PATTERN PERSISTS
THIS MORNING...MAKING AVIATION FORECASTING DIFFICULT. WILL FORECAST
MVFR TO OCCASIONALLY IFR CONDITIONS AT THE KGFL/KALB/KPOU/KPSF TAF
SITES THROUGH EARLY OR MID AFTERNOON. BUT CONDITIONS COULD ALSO
BRIEFLY BE VFR AT ANY OF THE TAF SITES DUE TO HOLES IN THE PCPN
SHIELD. PCPN WILL BE FORECAST AS JUST SNOW AT THE KALB/KGFL TAF
SITES...ALTHOUGH SOME SLEET COULD MIX IN AT KALB. AT KPOU MAINLY
RAIN IS FORECAST WITH OCCASIONAL PERIOD OF FREEZING RAIN/SLEET/SNOW.
SNOW OR SLEET IS FORECAST AT KPSF.
BY MID OR LATE AFTN EXPECT PCPN TO BE SCT TO NUMEROUS SNOW SHOWERS
WITH MAINLY MVFR CONDITIONS. MVFR/VFR CIGS AT THE TAF SITES AFTER
28/00Z WITH LITTLE OR NO ADDITIONAL PCPN EXPECTED...AND AFTER 06Z
VFR CONDITIONS EXPECTED AT ALL THE TAF SITES THROUGH THE END OF THE
TAF PERIOD (28/12Z).
SURFACE WINDS WILL BE NORTHERLY AT KGFL/KALB/KPOU THROUGH THIS
SUNDAY MORNING AT 10 TO 12 KTS WITH GUSTS UP TO 20 KTS. AT KPSF
WINDS WILL BE NORTHEAST AT 10 TO 15 KTS WITH GUSTS UP TO AROUND 25
KTS POSSIBLE. DURING THE DAY WINDS WILL GRADUALLY SHIFT TO NORTHWEST
AT 10 TO 15 KTS WITH GUSTS TO 20 TO 25 KTS AT ALL THE TAF
SITES...AND CONTINUE THAT WAY INTO SUNDAY EVENING...GRADUALLY
DIMINISHING SOMEWHAT OVERNIGHT.
OUTLOOK...
FRI-FRI NT...VFR. NO SIG WX.
SAT-MON...VFR/MVFR. CHC -SHSN.
&&
.HYDROLOGY...
A MAJOR WINTER STORM IMPACTING THE REGION INTO TODAY WITH MAINLY
MODERATE TO HEAVY SNOW. SLEET...FREEZING RAIN...AND RAIN ARE
EXPECTED MAINLY SOUTH AND EAST OF ALBANY...WHERE PRECIPITATION
TYPE WILL BE MOST VARIED. WITH THE BULK OF PRECIPITATION IN THE
HYDRO SERVICE AREA /HSA/ SNOW...OR FROZEN...THERE SHOULD BE
MINIMAL HYDROLOGIC RESPONSE...EXCEPT SOME MODEST WITHIN BANK RISES
IN SOUTHEASTERN NEW YORK AND LITCHFIELD COUNTY CONNECTICUT.
WE WILL HAVE TO MONITOR THE FLOOD STAGE AT POUN6..AS IT IS FORECAST
TO NICK IT WITH THE E/SE WINDS LATE THIS MORNING. IT MAY FALL
SHORT.
THURSDAY NIGHT INTO SATURDAY WILL HAVE SOME SCATTERED SNOW
SHOWERS MAINLY NORTH AND WEST OF THE CAPITAL REGION. SOME LIGHT
SNOW IS POSSIBLE LATE SATURDAY INTO SUNDAY. THE NEW WEEK WILL BE
MUCH COLDER...AND ICE MAY BEGIN TO FORM ON RIVERS AND LAKES OVER
THE HSA.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR CTZ001-
013.
NY...WINTER STORM WARNING UNTIL 7 PM EST THIS EVENING FOR NYZ032-
033-038>043-047>054-058>061-063-082>084.
WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR
NYZ064>066.
MA...WINTER STORM WARNING UNTIL 7 PM EST THIS EVENING FOR MAZ001-
025.
VT...WINTER STORM WARNING UNTIL 7 PM EST THIS EVENING FOR
VTZ013>015.
&&
$$
SYNOPSIS...SNYDER
NEAR TERM...KL/BGM/WASULA
SHORT TERM...SNYDER
LONG TERM...SNYDER
AVIATION...GJM
HYDROLOGY...SNYDER
AREA FORECAST DISCUSSION
NWS HASTINGS NE
547 AM CST THU DEC 27 2012
.AVIATION...12Z KGRI TAF...DETERIORATING CONDS EXPECTED AT KGRI
OVER THE NEXT FEW HOURS AS AN APPROACHING WINTER STORM SPREADS
SOME -SN AND REDUCED CIGS/VSBYS ACROSS THE AREA. WHILE PREVAILING
VFR CONDS ARE EXPECTED THROUGH ABOUT 27/14Z...WITH A SMALL CHANCE
OF A MVFR CIG/VSBY IN A PASSING BAND OF -SN...EXPECT PREVAILING
MVFR CIGS TO DEVELOP BY 27/14Z...WITH TEMPO IFR CIG/VSBY AS THE
BRUNT OF THE DISTURBANCE MOVES ACROSS SOUTH CENTRAL NEBRASKA
BETWEEN 27/14Z-27/18Z. THEREAFTER...CIGS WILL LIFT AND BECOME
MVFR...BUT PERSIST THROUGH THE END OF THE TAF PERIOD. OTHERWISE...
SOUTHEASTERLY WINDS THIS MORNING WILL REMAIN AROUND 10KTS THROUGH
27/23Z...BEFORE WINDS SLACKEN AND BECOME MORE VARIABLE THIS
EVENING.
&&
.PREV DISCUSSION... /ISSUED 243 AM CST THU DEC 27 2012/
SHORT TERM...THE MAIN ISSUE TO DEAL WITH IS TODAY/S LIGHT SNOW
EVENT.
WATER VAPOR AND INFRARED SATELLITE IMAGERY SUGGEST THE UPPER LEVEL
CIRCULATION SET TO IMPACT OUR AREA IS CENTERED IN THE TRI-STATE
CONFLUENCE OF WY/CO/NE. SPOKE OF ENERGY ALONG WITH WARM ADVECTION
PUSHING THROUGH THE FORECAST AT THIS TIME. RETURNS FROM NEARBY
RADARS SUGGEST PRECIPITATION IS DEVELOPING ALOFT IN THIS WARM
ADVECTION. NOTHING HAS REPORTEDLY MADE IT TO THE GROUND WITH DRY
AIR IN LOWER LEVELS OF THE ATMOSPHERE. THAT ALL SHOULD CHANGE
EARLY THIS MORNING...SAY AROUND DAWN...WITH LIGHT SNOWFALL STARTING
TO REACH THE SURFACE. SHORT TERM MODEL DATA /HRRR AND WRF/ POINT
TOWARD A BAND OF SNOW DEVELOPING IN THE VICINITY OF HIGHWAY 281
NAM QUICKLY LIFTING NORTH/NORTHEAST. THESE FINER DETAILS FIT WITH
THE NAM/GFS/SREF OUTPUT...WHICH EVENTUALLY PUT THE GREATEST
PRECIPITATION IN NORTHEAST NEBRASKA OF ABOUT 0.30". MEANWHILE...
THE NORTH/EAST FORECAST AREA MAY PICK UP A TENTH OR TWO OF LIQUID
EQUIVALENT MOISTURE...EQUATING INTO 1 TO 2 INCHES...MAYBE LOCALLY
3 INCHES OF SNOW. THE AREA AT MOST RISK FOR 3 INCHES...AND IT MAY
NOT BE THAT MUCH RISK...WOULD BE NORTHERN NANCE COUNTY...OR NORTHEAST
GREELEY COUNTY. THE VAST MAJORITY OF OUR NEBRASKA FORECAST IS IN
THE 1 TO 2 INCH RANGE...WITH LESS THAN 1 INCH IN NORTHERN KANSAS.
AT THIS TIME...WITH LIMITED WIND INFLUENCES...AND ONLY A SMALL PART
OF THE FORECAST AREA IN LINE FOR MARGINAL ADVISORY LEVEL SNOW
AMOUNTS...WILL NOT ISSUE ANY HEADLINES. IN FACT...IF YOU BUY INTO
THE 05Z HRRR OUTPUT...ONLY THE FAR NORTHEAST FORECAST AREA WOULD
CATCH 1 TO 2 INCHES OF SNOW...AND THE REST OF THE AREA AN INCH OR
LESS. AT THIS POINT...THERE SEEMS TO BE ENOUGH REASON NOT TO ISSUE
ANY ADVISORIES FOR THIS EVENT.
SHOULD MENTION...NAM SOUNDINGS IN THE SOUTHEAST PART OF THE FORECAST
AREA...ALONG WITH FUZZY NATURE OF PRECIPITATION OUTLOOK...SUGGEST A
BIT OF FREEZING DRIZZLE COULD DEVELOP DURING THE EVENING HOURS. LIFT
IS THE QUESTION...MEANING IS THERE ENOUGH? THINK THERE COULD BE A
COUPLE OF HOURS OF FREEZING DRIZZLE TYPE PRECIPITATION IN THIS AREA
AND HAVE ADDED THAT TO THE FORECAST GRIDS. NOT A HUGE DEAL...AND MAY
NOT MATERIALIZE...BUT WOULDN/T BE SHOCKED IF IT DID PAN OUT.
ON FRIDAY...THE MEANDERING NATURE OF THE UPPER LEVEL LOW TO THE
SOUTHEAST WILL KEEP CLOUDS AROUND FOR A GOOD PART OF THE DAY. FAR
EASTERN FORECAST AREA MAY EVEN SEE A LINGERING FLURRY EARLY IN THE
MORNING. ASIDE FROM THAT...NORTHWEST WINDS WILL DEVELOP...AND MAY
EVEN TURN SNEAKY BREEZY IF CLEARING DEVELOPS MORE RAPIDLY. FRIDAY
IS STILL A PART OF THE CURRENT COLD SPELL WITH HIGHS STRUGGLING FOR
ABOUT 20 MOST AREAS. THAT ALL STARTS TO CHANGE FRIDAY NIGHT...AS
DOWN-SLOPING WESTERLY WINDS SET UP AND LASTS INTO THE DAY SATURDAY.
THIS WILL RESULT IN SATURDAY BEING MUCH WARMER...RELATIVE TO RECENT
DAYS...WITH HIGHS IN THE UPPER 20S AND LOWER 30S AND PLENTY OF
SUNSHINE. THAT WON/T NECESSARILY MELT A WHOLE LOT...AND ITS STILL
BELOW NORMAL SOME 5 TO 7 DEGREES...BUT ITS AT LEAST A START.
LONG TERM...STARTING SUNDAY MORNING...SUNDAY IS SHAPING UP TO BE
THE WARMEST DAY IN JUST OVER A WEEK AS THE COMBINATION OF WARMER AIR
SURGING NORTHWARD AHEAD OF AN APPROACHING LOW LEVEL TROUGH/FRONT AND
MOSTLY SUNNY SKIES UNDER THE INFLUENCE OF A BUILDING UPPER LEVEL
RIDGE...WILL RESULT IN A RETURN TO NEAR SEASONAL TEMPERATURES FOR
THE END OF DECEMBER. AS A RESULT...EXPECT TO SEE AFTERNOON
TEMPERATURES ACROSS SOUTH CENTRAL NEBRASKA APPROACH THE FREEZING
MARK...WITH UPPER 30S TO NEAR 40 DEGREES CURRENTLY FORECAST FOR
PORTIONS OF NORTH CENTRAL KANSAS. WHILE THIS LIKELY WILL NOT BE WARM
ENOUGH TO RESULT IN ANY SIGNIFICANT MELTING OF SNOW/ICE ON THE
GROUND...IT WILL LIKELY BE THE FIRST DAY SINCE DECEMBER 22ND THAT
TEMPERATURES WILL CLIMB ABOVE THE FREEZING MARK ACROSS THE MAJORITY
OF THE FORECAST AREA. THIS BRIEF WARM UP...HOWEVER...IS EXPECTED TO
BE FAIRLY SHORT LIVED...AS GLOBAL MODELS ARE INDICATING COOLER AIR
BEHIND THE APPROACHING TROUGH/FRONT...WHICH WILL BEGIN TO FILTER IN
ACROSS THE LOCAL AREA TO START THE NEW WORK WEEK. AS A
RESULT...EXPECT A RETURN TO SUBFREEZING AFTERNOON TEMPERATURES
MONDAY AFTERNOON WITH LITTLE EVIDENCE FOR ENOUGH LOW LEVEL MOISTURE
OR FORCING TO JUSTIFY ANYTHING OTHER THAN AN INCREASE IN CLOUDS
ACROSS THE LOCAL AREA MONDAY.
THEREAFTER...THE GLOBAL MODELS BEGIN TO DIVERGE SOME WITH THEIR
HANDLING OF AN UPPER LEVEL LOW ACROSS THE DESERT SOUTHWEST...WITH
THE GFS MAINTAINING A MUCH MORE PROGRESSIVE FLOW PATTERN THAN THE
EC...WHICH HAS BEEN TRYING TO CUT OFF THE UPPER LEVEL LOW ACROSS
NORTHERN MEXICO. HOWEVER...IN BOTH SCENARIOS...THE NORTHERN JET IS
FORECAST TO STEER AN UPPER LEVEL DISTURBANCE ACROSS NEBRASKA TUESDAY
NIGHT/WEDNESDAY...WHICH ONCE AGAIN IS EXPECTED TO HAVE A LACK IN
APPRECIABLE LOW LEVEL MOISTURE...WITH LITTLE MORE THAN A FEW HIGH
CLOUDS AND A CONTINUATION OF SUB FREEZING TEMPERATURES EXPECTED TO
PERSIST AS A RESULT. JUST BEYOND THE CURRENT SCOPE OF THE
FORECAST...THERE ARE SOME INDICATIONS THAT ANOTHER UPPER LEVEL RIDGE
OF HIGH PRESSURE WILL BUILD ACROSS THE CENTRAL PLAINS IN CONCERT
WITH A MORE SIGNIFICANT DOWN-SLOPING LOW LEVEL FLOW...WHICH MAY
RESULT IN TEMPERATURES WARMING ABOVE CLIMO TOWARDS THE END OF NEXT
WEEK.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
542 AM CST THU DEC 27 2012
.AVIATION...
LIGHT SNOW IS EXPECTED TO CONTINUE NORTH AND WEST OF AN
ANW-TIF-MHN-OGA LINE THROUGH 21Z WITH THE HEAVIEST FROM 14-18Z.
CEILINGS BELOW 3000 FEET AGL ARE LIKELY WITH A FAIRLY STRONG
PROBABILITY OF 1000-2000 FEET AGL. IN ADDITION...WIDESPREAD
VISIBILITY BELOW 3SM CAN BE EXPECTED IN THE HEAVIER SNOW WITH LESS
THAN 1SM POSSIBLE. LOW CEILING AND VISIBILITY MAY CONTINUE UNTIL AT
LEAST THIS EVENING 03Z...ESPECIALLY IN NORTH CENTRAL NEBRASKA.
&&
.PREV DISCUSSION... /ISSUED 354 AM CST THU DEC 27 2012/
SHORT TERM...TODAY THROUGH SATURDAY NIGHT
FORECAST CONCERNS THROUGH THIS PERIOD ARE SNOWFALL CHANCES AND
AMOUNTS FOR TODAY AND TONIGHT...THEN TEMPERATURES INTO THE
WEEKEND.
AT 08Z...WATER VAPOR IMAGERY SHOWED THE STRONG LOW PRESSURE SYSTEM
IMPACTING THE EAST COAST CENTERED OVER EASTERN VIRGINIA. RIDGING
WAS SITUATED OVER THE MISSISSIPPI RIVER VALLEY AS A FAIRLY LARGE
TROUGH COVERING THE WESTERN HALF OF THE CONUS. COMING OUT OF THE
TROUGH WAS AN UPPER LOW OVER EASTERN WYOMING...WHILE A PV ANOMALY
WAS SEEN OVER EASTERN COLORADO MOVING TOWARDS WESTERN NEBRASKA.
LOCALLY...RADAR ECHOES SPANNED ACROSS THE EASTERN PANHANDLE INTO
NORTHWEST NEBRASKA...WITH MORE CONVECTIVE LOOKING ECHOES OVER
CENTRAL NEBRASKA. NO PRECIPITATION WAS BEING REPORTED WITH THE
EASTERN ACTIVITY WHILE KAIA AND KSNY IN THE PANHANDLE HAD REPORTED
LIGHT SNOW BEING JUST OUTSIDE OF THE MAIN SNOW BAND. MODELS WOULD
INDICATE THE 700MB LOW OVER THE WESTERN PANHANDLE. THERE WAS A
GOOD MOISTURE FEED JUST TO THE EAST OF THE LOW WHICH HAD ITS
PRIMARY FOCUS INTO NORTHWEST NEBRASKA. THE RAP MODEL ALSO WAS
INDICATING SOME FRONTOGENETICAL FORCING AT 700 TO 600MB IN THIS SAME
AREA...WHICH WOULD FIT WITH WHAT IS ONGOING.
AS THE MORNING PROGRESSES...THE UPPER LOW OVER WYOMING WILL SHIFT
EAST INTO NORTH CENTRAL NEBRASKA AROUND MID-DAY THEN CONTINUE EAST
ALONG THE SOUTH DAKOTA/NEBRASKA BORDER INTO TONIGHT. ISENTROPIC
SURFACES FROM ROUGHLY 275K TO 290K ALL SHOWING DECENT LIFT AS WELL
AS MOISTURE TRANSPORT THROUGH THE MORNING /MAINLY OVER NORTHERN
NEBRASKA/...WHICH THEN SHIFTS EAST THIS AFTERNOON. HAVE ADJUSTED
PRECIPITATION CHANCES IN THIS FORECAST TO INCLUDE THE HIGHEST
CHANCES OVER THE PANHANDLE AND NORTHWEST NEBRASKA THIS
MORNING...THEN INTO NORTH CENTRAL NEBRASKA THIS AFTERNOON AS THE
WHOLE SYSTEM MOVES EAST. CONTINUED THE CHANCES OVER SOUTHWEST
NEBRASKA TODAY...BUT CONFIDENCE IS MUCH LESS IN THESE AREAS AND
DID BACK OFF ON CHANCES A BIT. REASONING FOR THIS IS THAT THIS
AREA WILL BE IN A FAVORABLE LOCATION FOR DRY AIR TO COME INTO THE
SYSTEM AROUND THE UPPER LOW...ALSO THE PV ANOMALY OVER COLORADO
HAS GOOD DARKENING IN THE WATER VAPOR IMAGERY INDICATING GOOD DRY
AIR ASSOCIATED WITH IT. AS THIS MOVES INTO SOUTHWEST NEBRASKA...IT
SHOULD LIMIT THE SNOWFALL. WILL PROBABLY SEE SOME SNOW IN THESE
AREAS THROUGH THE DAY...BUT BELIEVE IT WILL BE QUITE LIGHT AND
WILL NOT LAST LONG SO VERY LITTLE IF ANY ACCUMULATION IS EXPECTED.
IF IN FACT THIS OCCURS...THE FORECAST WILL LIKELY NEED TO BE
UPDATED TO REFLECT THE LOWER CHANCES FOR MEASURABLE SNOWFALL IN
THESE AREAS.
THE SYSTEM WILL NOT BE REAL FAST MOVING OUT OF THE LOCAL
AREA...WHICH WILL KEEP SNOW FALLING ACROSS NORTH CENTRAL NEBRASKA
TONIGHT BEFORE EXITING COMPLETELY ON FRIDAY. THERE HAS BEEN GOOD
MODEL AGREEMENT WITH KEEPING THE HIGHER SNOWFALL AMOUNTS JUST EAST
OF THE FORECAST AREA...MAINLY ALONG AND EAST OF HIGHWAY 14.
SOUNDINGS CONTINUE TO SHOW THE ENTIRE SATURATED LAYER /SURFACE
THROUGH 600MB/ IN THE DENTRITIC GROWTH ZONE...SO USED HIGH SNOW
RATIOS VARYING FROM 18:1 TO 23:1. EVEN WITH THIS...STORM TOTAL
SNOW AMOUNTS ACROSS HOLT AND BOYD COUNTIES ONLY SHOWING 2 TO 3
INCHES WITH A FEW LOCALIZED AREAS ABOVE 3 INCHES. GOING EAST OF
THE AREA AMOUNTS IN EXCESS OF 3 INCHES ARE LIKELY. WINDS SHOULD BE
FAIRLY LIGHT TODAY UNDER 15 MPH SO EVEN WITH THE HIGH SNOW
RATIOS GIVING HIGHER SNOW AMOUNTS DON/T FEEL THE IMPACTS WILL BE
HIGH SO WILL NOT PUT OUT AN ADVISORY FOR TODAY AND TONIGHT.
COLD AIR WILL REMAIN IN PLACE OVER THE FORECAST AREA TODAY...AND
WITH THE CLOUD COVER DON/T EXPECT HIGHS TO GET OUT OF THE TEENS.
TONIGHT AND FRIDAY...THE PRIMARY TROUGH WILL EXTEND FROM THE NORTHERN
PLANS THROUGH THE FOUR CORNERS. MEANWHILE...SEVERAL WEAK IMPULSES
OF SHORTWAVE ENERGY WILL QUICKLY PUSH SOUTH OUT OF CANADA INTO THE
CENTRAL PLAINS. THIS SHOULD KEEP AT LEAST SOME HIGH CLOUDS...BUT
MAY NOT BE TOO THICK. DID DROP LOWS ACROSS THE WESTERN PARTS OF
THE FORECAST AREA NEAR ZERO OR SLIGHTLY BELOW ZERO. IF CLOUDS
CLEAR...COULD CERTAINLY BE TOO WARM.
THE TROUGH DOES MOVE EAST INTO THE MISSISSIPPI RIVER VALLEY FRIDAY
NIGHT AND SATURDAY ALLOWING RIDGING TO START TO BUILD IN FOR THE
WEEKEND. THIS WILL BE THE START TO A SLOW WARMING TREND INTO NEXT
WEEK. NOT LOOKING FOR TEMPERATURES TO WARM DRAMATICALLY AS
SATURDAY HAS HIGHS NEAR THE FREEZING POINT. AREAS WITH SNOW COVER
WILL SEE A GREATER IMPACT IN TEMPERATURES SO IT IS LIKELY THAT
THERE WILL BE ADJUSTMENTS AFTER THE SNOW FIELD IS SAMPLED AFTER
TONIGHT.
LONG TERM...SUNDAY THROUGH WEDNESDAY
THIS PERIOD BEGINS WITH RIDGING ACROSS THE PLAINS...HOWEVER THERE
IS GOOD CONSENSUS FROM THE MODEL OUTPUT BRINGING THE NEXT STRONG
TROUGH INTO THE WEST COAST ON SUNDAY. ALSO...SEVERAL STRONG
SHORTWAVE TROUGHS ARE BEING SHOWN IN THE NORTHERN STREAM WHICH
COULD COME SOUTH FAR ENOUGH TO KEEP THE RIDGE FROM BUILDING TOO
FAR NORTH. THIS WILL KEEP TEMPERATURES FROM MODERATING TOO MUCH
THROUGH THE FIRST PART OF NEXT WEEK. THE FIRST OF THESE SYSTEMS
COMES THROUGH SUNDAY NIGHT...WHICH SHOULDN/T HAVE ANY OTHER IMPACT
BUT TO BRING SOME COOLER AIR SOUTH INTO NEBRASKA. FOR MONDAY AND
BEYOND...THE MODELS BEGIN TO DIVERGE WITH THE EASTERN MOVEMENT OF
THE WEST COAST TROUGH. THE ECMWF IS SLOWER...WHICH THEN ALLOWS A
STRONG NORTHERN STREAM SYSTEM TO PENETRATE INTO NEBRASKA TUESDAY
NIGHT. THE GFS IS QUICKER AND KEEPS THIS SYSTEM UP OVER MINNESOTA
AND THE GREAT LAKES. EITHER WAY...MOISTURE LOOKS TO BE HELD TO THE
THE MAIN UPPER LOW WHICH STAYS WELL SOUTH SO NO FURTHER
PRECIPITATION CHANCES ARE IN THE FORECAST BEYOND FRIDAY MORNING.
HYDROLOGY...
ICE JAMS ARE LIKELY TO CONTINUE AT VARIOUS LOCATIONS IN CENTRAL
AND WESTERN NEBRASKA. EXCEPT FOR STRETCHES ALONG THE NORTH PLATTE
RIVER...THERE ARE NO INDICATIONS OF FLOODING. BE AWARE THAT THE
FORMATION AND BREAK-UP OF ICE JAMS ARE NOTORIOUSLY DIFFICULT TO
FORECAST...SO RIVERS AND STREAMS IN THE AREA MAY RISE AND FALL
ERRATICALLY. WE DO HAVE FAIRLY HIGH CONFIDENCE THAT...WITH
TEMPERATURES MODERATING SOME...THE LEVELS ARE NOT LIKELY TO HAVE
NEW SHARP RISES ABOVE CURRENT LEVELS.
THE NORTH PLATTE RIVER AT LEWELLEN CONTINUES TO FALL
SLOWLY...POSSIBLY BECAUSE THE RIVER HAS BECOME COMPLETELY FROZEN
AND THE ICE IS NO LONGER BEING CARRIED TOWARD THE INLET OF LAKE
MCCONAUGHY. AT THE NORTH PLATTE GAGE...THE LEVEL CONTINUES ABOVE
FLOOD STAGE AND IS LIKELY TO CONTINUE FOR AT LEAST THIS WEEKEND.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM/EXTENDED...BROOKS
AVIATION/HYDROLOGY...SPRINGER
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
525 AM CST THU DEC 27 2012
.AVIATION...
12Z TAFS FOR KOFK...KOMA AND KLNK.
ONE BAND OF SNOW MOVING ACROSS EASTERN NEBRASKA THIS MORNING WILL
BRING LOWERING CIGS AND SNOW CHANCES TO TAF SITES. KOFK SHOULD BE
ESPECIALLY IMPACTED BY THIS FIRST ROUND AND TEMPO IFR CONDITIONS
WERE FORECAST THERE. A LULL IS THEN EXPECTED LATER THIS MORNING
INTO THIS AFTERNOON AT KOMA/KLNK...ALTHOUGH SNOW SHOULD PERSIST
AT KOFK. A PERIOD OF FREEZING DRIZZLE WAS MENTIONED AT KOMA/KLNK
LATE THIS AFTERNOON OR EARLY THIS EVENING AS LOW LEVELS SATURATE
BUT LIFT/MOISTURE NOT ESPECIALLY SUPPORTIVE FOR SNOW. CONFIDENCE
IN VSBY/PRECIP EVOLUTION...HOWEVER...NOT VERY HIGH AND ADJUSTMENTS
IN FORECAST LIKELY.
CHERMOK
&&
.PREV DISCUSSION... /ISSUED 302 AM CST THU DEC 27 2012/
DISCUSSION...
..SNOW AMOUNTS AND CHANCES FOR FREEZING DRIZZLE THE MAIN
CONCERNS...
FOR THIS FORECAST THE MAIN FEATURE OF INTEREST WILL BE THE POTENT
SHORTWAVE THAT IS CURRENTLY SPINNING ALONG THE WYOMING-COLORADO
BORDER PER WATER VAPOR LOOP AND THE PRECIPITATION IT WILL PRODUCE
TODAY AND FRIDAY. THE MORE THIS SYSTEM DEVELOPS THE MORE
IMPRESSIVE IT APPEARS TO BE...ESPECIALLY FOR NORTHEAST NEBRASKA.
500 MB HEIGHT FALLS ON THE 00Z RAOBS WERE 100-120 METERS IN THE
BASE OF THE TROF...WITH DENVER SHOWING A 130 METER FALL AT 300 MB.
150 KNOT JET STREAK WAS NOTED AT 25O MB OVER ARIZONA. REGIONAL
RADAR MOSAIC SHOWS SNOW RAPIDLY DEVELOPING/EXPANDING FROM WESTERN
KANSAS INTO WESTERN AND CENTRAL NEBRASKA IN RESPONSE TO THE
SYSTEMS VERTICAL MOTION AND MOISTURE AROUND 850 MB AS SEEN ON
DODGE CITY AND NORTH PLATTE SOUNDINGS. 08Z SURFACE ANALYSIS SHOWED
EARLY STAGES OF INVERTED TROF TAKING SHAPE WITH 1003MB PRESSURES
OBSERVED IN SOUTHEAST COLORADO.
THE DODGE CITY AND NORTH PLATTE SOUNDINGS DID HAVE A FEW DRY
LAYERS AS WELL...AND THESE DRY LAYERS DO COMPLICATE THE
PRECIPITATION FORECAST. GENERALLY THE NAM/GFS/RAP ARE IN DECENT
AGREEMENT ON THE PRECIPITATION FORECAST AND THE MOIST AND DRY
LAYERS. HOWEVER THERE IS CONCERN FOR A LIGHT FREEZING DRIZZLE
SCENARIO MAINLY IN THE SOUTHERN HALF OF THE FORECAST AREA DUE TO A
LOW LEVEL SATURATED LAYER THAT IS WARMER THAN -10C AND THEREFORE
WOULD PRIMARILY CONTAIN SUPERCOOLED DRIZZLE AS OPPOSED TO
SNOWFLAKES. THE MODELS SHOW LITTLE OR NO QPF OVER SOUTHEAST
NEBRASKA THROUGH 12Z FRIDAY...HOWEVER THE MODELS OFTEN POORLY HANDLE
THESE VERY LIGHT ICING EVENTS BECAUSE THE QPF IS QUITE LIGHT BUT
ALSO BECAUSE THE LAYERS ARE SHALLOW. THE FORECAST SOUNDINGS FROM
THE NAM AND ESPECIALLY THE RAP SUPPORT AT LEAST SOME LIGHT
FREEZING DRIZZLE MAINLY ALONG AND SOUTH OF INTERSTATE 80 AT
VARIOUS TIMES FROM LATE THIS AFTERNOON INTO TONIGHT...THEREFORE
WE HAVE ADDED PATCHY FREEZING DRIZZLE...OR AREAS OF FREEZING
DRIZZLE...TO THE SNOW CHANCES IN THOSE LOCATIONS. CONFIDENCE IN
THIS LIGHT ICING SCENARIO IS NOT HIGH ENOUGH TO ISSUE A WINTER
WEATHER ADVISORY FOR THE ABOVE MENTIONED AREAS. HOWEVER IF NEW
OBSERVATIONS AND MODEL RUNS SUGGEST A HIGHER LIKELIHOOD OF
FREEZING DRIZZLE AN ADVISORY MAY BE CONSIDERED LATER TODAY.
OTHERWISE THE TRACK OF THE LOW FAVORS THE HEAVIER SNOWS TO FALL IN
NORTHEAST NEBRASKA WHERE THE GOING WINTER WEATHER ADVISORY IS AT.
WE DID ADD ONE MORE TIER OF COUNTIES TO THE ADVISORY INCLUDING
ALBION AND NORFOLK. THIS SYSTEM IS UNIQUE IN THAT IT HAS A VERY
DEEP SATURATED LAYER THAT IS IN THE DENDRITIC GROWTH ZONE...AROUND
250 MB OR ABOUT 10000 FEET DEEP...YIELDING SNOW-LIQUID RATIOS AS
HIGH AS 20-1. BECAUSE OF THIS WE ALSO INCREASED SNOW AMOUNTS IN
NORTHEAST NEBRASKA ABOUT 1 MORE INCH. FORTUNATELY THERE WILL NOT
BE A LOT OF WIND WITH THIS SYSTEM SO LITTLE BLOWING AND DRIFTING
IS EXPECTED. SOME LOCATIONS IN THE ADVISORY AREA SHOULD SEE 4-5
INCHES OF DRY/FLUFFY SNOW STARTING TODAY AND ENDING FRIDAY
MORNING.
CONFIDENCE IN THE EXACT SNOW AMOUNTS IS MUCH LOWER TO THE SOUTH
OF THE ADVISORY AREA...MAINLY FROM THE LINCOLN TO OMAHA METRO
AREAS. HOWEVER...THERE IS LITTLE SUPPORT FOR MORE THAN 2 INCHES
GIVEN THE DRY LAYERS THAT WILL NEED TO BE SATURATED AND THE
WEAKER FORCING JUST SOUTH OF THE 700 MB LOW TRACK. CURRENTLY WE
ARE KEEPING THE 1-2 INCH AMOUNTS FOR LINCOLN-OMAHA AND THIS LOOKS
REASONABLE BY NOON FRIDAY WHEN ANY LIGHT SNOW ON THE BACK SIDE OF
THE LOW FINALLY ENDS. STARTED THE CHANCES FOR SNOW A BIT LATER
EAST OF A LINE FROM LINCOLN TO FREMONT...MAINLY CLOSER TO 18Z
TODAY...PRIMARILY DUE TO THE TIME IT WILL TAKE TO SATURATE THE
DRY LOW LEVELS IN THAT AREA.
TEMPERATURE AND WIND FORECASTS WERE ONLY SLIGHTLY ADJUSTED AS THE
PATTERN REMAINS FAIRLY COLD BUT DRY AFTER FRIDAY.
NIETFELD
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...WINTER WEATHER ADVISORY FROM NOON TODAY TO 6 AM CST FRIDAY FOR
NEZ011-012-015>018-030>033.
IA...WINTER WEATHER ADVISORY FROM NOON TODAY TO 6 AM CST FRIDAY FOR
IAZ043.
&&
$$
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
540 AM EST THU DEC 27 2012
.SYNOPSIS...
LOW PRESSURE SYSTEM EXITS EAST TODAY. ANOTHER LOW PRESSURE SYSTEM
FRIDAY NIGHT AND SATURDAY...WITH MORE MIXED PRECIPITATION...CHANGING
TO SNOW OVERNIGHT SATURDAY AND SUNDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
RADAR AND MODELS SHOWING LIGHT SNOW OR FREEZING DRIZZLE MOVING INTO
THE EASTERN MOUNTAINS WHILE DIMINISHING ACROSS THE WESTERN HALF OF
THE AREA THIS MORNING. LOW CLOUDS WILL PERSIST OVER A SHALLOW
SATURATED LAYER TODAY...LIFTING TONIGHT. HOWEVER...HIGH LEVEL
CLOUDS ASSOCIATED WITH A FAR AWAY SYSTEM WILL COVER PORTIONS OF OUR
SKIES THROUGH THIS EVENING.
VERY COLD AIR CONTINUES TO FILTER IN UNDER WEST NORTHWEST FLOW WITH
H850 TEMPS WARMING FROM MINUS 9C TO MINUS 5C BY 18Z THIS AFTERNOON
AND TONIGHT. THEREFORE...WITH CLOUDS EXPECTED AND VERY COLD AIR MASS
IN PLACE...TODAYS TEMPERATURES WILL REMAIN AT OR BELOW
FREEZING...EXCEPT FOR POCKETS JUST ABOVE OVER THE LOWLANDS. THESE
LOW TEMPERATURES WILL KEEP ANY WET SURFACE FROZEN...TO PRODUCE BLACK
ICE WHERE WATER USUALLY DRAINS FROM SLOPES...AND ON EXPOSED BRIDGES
AND OVERPASSES. DRIVERS SHOULD EXERCISE CAUTION WHEN TRAVELING
TODAY.
FOR TONIGHT...DRIER CONDITIONS WITH LESS CLOUDS. LOWS GENERALLY IN
THE MID 20S LOWLANDS...RANGING TO THE TEENS HIGHER ELEVATIONS.
HOWEVER...WINDS WILL DIMINISH TONIGHT...KEEPING SIMILAR WINDCHILL AS
TODAY.
GUSTY WINDS WILL PRODUCE WINDCHILL IN THE 20S LOWLANDS...RANGING
INTO NEAR ZERO AT THE HIGHEST PEAKS NORTHEAST MOUNTAINS.
A WIND WIND ADVISORY REMAINS IN EFFECT FOR POCAHONTAS COUNTY THROUGH
AT LEAST 1 PM THIS AFTERNOON.
WENT WITH A BLEND OF THE GMOS AND RUC MODELS FOR TEMPERATURES
THROUGH THE PERIOD.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
FRIDAY A SHORT BREAK IN THE ACTIVE WEATHER PATTERN TAKES PLACE WITH
S/W RIDGE OVERHEAD AT 12Z QUICKLY MOVING EAST WITH UPPER FLOW
TURNING SOUTHWESTERLY IN ADVANCE OF THE NEXT RAPIDLY-APPROACHING
UPPER LEVEL TROUGH MOVING ACROSS THE CENTRAL MISS VALLEY AREA. SFC
HIGH PRESSURE SLIDES OFF TO THE EAST WITH RETURN SOUTHERLY FLOW.
OVERALL A PARTLY CLOUDY DAY GENERALLY SPEAKING WITH MORE CLOUDS TO
START THE DAY AND CLOUDS INCREASING ACROSS THE WEST BY END OF DAY.
LOOKS LIKE A DECENT TEMPERATURE GRADIENT FORMS ACROSS THE AREA AS A
WARM FRONTAL FEATURE SETS UP ROUGHLY FROM POCAHONTAS COUNTY WSW-WARD
TOWARDS HTS BY FRI MID-AFTERNOON. FAR NW ZONES WHERE RESIDUAL SNOW
COVER REMAINS WILL ONLY REACH THE MID/UPPER 30S WHEREAS FAR SOUTHERN
ZONES...WHERE 925MB TEMPS ARE PROGGED TO REACH AROUND 5.5C TO
6C...WILL PUSH 50 DEGREES AND POTENTIALLY INTO THE LOWER 50S. FRIDAY
NIGHT...LARGE SCALE ASCENT OVERSPREADS THE FORECAST AREA FROM WEST
TO EAST AS AFOREMENTIONED TROUGH CONTINUES TOWARD THE AREA WITH AXIS
ENTERING THE CWA AROUND 12Z SAT WITH SFC COLD FRONT MOVING INTO CWA
WITH IT. BEST DEEP LAYER MOISTURE WILL BE ALONG AND AHEAD OF SFC
FRONT SO WILL HAVE BEST OVERALL POPS DURING THE OVERNIGHT PERIOD.
MEANWHILE OVERNIGHT THE WARM FRONT QUICKLY LIFTS NORTHWARD WITH
DEVELOPING SFC LOW ACROSS NORTH OF LAKE ERIE IN SW ONTARIO. RAISED
MINS A BIT TO ACCOUNT FOR LLVL WARM ADVECTION AT 850MB...ALBEIT IT
IS RELATIVELY WEAK. AS A RESULT...WILL KEEP THE RAIN/SNOW MIX LINE
NORTH OF THE INTERSTATE 64 CORRIDOR FRI NIGHT/SAT MORNING AND ALL
SNOW ALONG AND NORTH OF A LINE ROUGHLY FROM PKB TO CKB AND ACROSS
THE HIGHER ELEVATIONS. SATURDAY AS THE INITIAL TROUGH AND COLD FRONT
CONTINUE EASTWARD...DEEP LAYER MOISTURE WANES AS DO THE HIGHER POPS.
A SOLID 3-5KFT LLVL OF SATURATION WILL REMAIN...AND AS SUCH SATURDAY
STAYS CLOUDY. MEANWHILE THE UPPER TROUGH DIGS TO THE WEST AGAIN AS
COLD ADVECTION CONTINUES BEHIND FRONT. LONG STORY SHORT...CHANCES
FOR PRECIP DWINDLE SOMEWHAT DURING THE DAY BUT RAMP BACK UP ONCE
AGAIN PARTICULARLY AFTER 21Z SAT AS SECONDARY UPPER TROUGH AXIS
APPROACHES FROM THE WEST AND MEAGER LLVL MOISTURE DEEPENS A BIT.
AIDING IN PRECIP PRODUCTION WILL BE THE STEEPENING LLVL LAPSE RATES
WITH THE UPPER TROUGH APPROACH WHICH MAY ADD A LEVEL OF CONVECTIVE
ENHANCEMENT. BY SATURDAY EVENING AND SATURDAY NIGHT A SECONDARY PUSH
OF COLD ADVECTION INTO THE AREA SHOULD RESULT IN A CHANGEOVER TO ALL
SNOW FOR THE ENTIRE AREA BY 03Z-06Z SUN. SNOW ACCUMULATIONS ARE
EXPECTED TO REMAIN LIGHT HOWEVER...WITH A DUSTING TO PERHAPS AROUND
A HALF INCH FOR MOST LOWLAND LOCATIONS AND ONE TO TWO INCHES FOR
ELEVATIONS ABOVE ABOUT 2.5KFT.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
MODELS SHOWING AN UPSLOPE EVENT DEVELOPING SATURDAY NIGHT AND
CONTINUING ON SUNDAY BEHIND A LOW PRESSURE SYSTEM. HIGH PRESSURE
THEN BUILDS IN SUNDAY NIGHT. MODELS THEN DIVERGE CONSIDERABLY ON
SOLUTIONS FOR MONDAY THROUGH WEDNESDAY. USED A BLEND OF THE GEFS AND
ECMWF ENSEMBLE MEANS DURING THIS PERIOD...WITH SLIGHTLY MORE
EMPHASIS ON THE ECMWF ENSEMBLE MEAN.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
RADAR IMAGES SHOW ROTATING ECHOS JUST EAST OF PA AND NORTHERN OH.
SHALLOW MOISTURE LAYER STILL PRODUCING LIGHT FREEZING DRIZZLE UNDER
STRONG GUSTY WINDS PEAKING JUST BELOW 40 KNOTS AT HIGHER
ELEVATIONS. THEREFORE...EXPECT MVFR/IFR CONDITIONS IN LOW STRATUS
OR LIGHT PCPN THIS MORNING. CONDITIONS IMPROVING BY NOON TIME FROM
WEST TO EAST...WITH EKN AND BKW THE LATEST TO IMPROVE AROUND
18-21Z THIS AFTERNOON.
NORTHWEST FLOW PREVAILS THROUGH TONIGHT...DECREASING LATER
OVERNIGHT.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z FRIDAY...
FORECAST CONFIDENCE: MEDIUM.
ALTERNATE SCENARIOS: DURATION AND EXTENT OF LOWER CIGS AND VSBYS
IN PRECIPITATION COULD VARY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 11 12 13 14 15 16 17 18 19 20 21 22
EST 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17
CRW CONSISTENCY L L L L L L L L L L L L
HTS CONSISTENCY H H H L L L L H H H M H
BKW CONSISTENCY H M M L L L L L L L L L
EKN CONSISTENCY M M M L L L L L L L L L
PKB CONSISTENCY L L L L L L L H H H M L
CKB CONSISTENCY M M L L L L L L L L L L
AFTER 12Z FRIDAY...
IFR POSSIBLE IN SNOW SATURDAY INTO SUNDAY...ESPECIALLY IN THE
MOUNTAINS.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...WIND ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR WVZ046.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...ARJ/50
NEAR TERM...ARJ
SHORT TERM...50
LONG TERM...RPY
AVIATION...ARJ
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
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 COUND 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.
&&
.PREV DISCUSSION... /ISSUED 1007 AM MST THU DEC 27 2012/
UPDATE...
SHORT TERM...MOUNTAIN WEB CAMS SHOWING SNOW ACROSS MUCH OF THE
REGION. WITH MOIST WEST NORTHWEST FLOW ALONG TO PERSIST THROUGH
MUCH OF THE DAY ALONG WITH LAPSE RATES AROUND 6 C/KM WEAK MID
LEVEL QG ASCENT...SNOW SHOULD CONTINUE INTO THE EVENING WITH
ANOTHER 3-6 INCHES. CURRENT ADVISORIES TO CONTINUE. SOME DECREASE
IN THE SNOW STILL EXPECTED OVERNIGHT AS ASCENT WEAKENS AND
SUBSIDENCE PREVAILS. ACROSS PLAINS...THE LIGHT SNOW OVER THE
NORTHEAST CORNER HAS ENDED WITH MOSTLY CLOUDY CONDITIONS
PREVAILING. LATEST MODELS CONTINUE TO SHOW WEAK DISTURBANCE MOVING
ACROSS THE CENTRAL PLAINS WITH WEAK UPSLOPE LOW DEVELOPING ALONG
THE FRONT RANGE. RAP/RUC SHOW SOME LIGHT PRECIP/QPF DEVELOPING
ACROSS THE NORTHERN FRONT RANGE AND PALMER DIVIDE AREA DURING THE
AFTERNOON WITH THE NORTHERN BATCH GRADUALLY SPREADING SOUTHWARD
BY EVENING. THERE STILL IS THE POTENTIAL FOR SOME LIGHT SNOW IN
AND NEAR THE FRONT RANGE. LATEST MODELS SEEM TO FAVOR THE NORTHERN
PORTIONS OF THE FRONT RANGE AS WELL AS NEAR THE FOOTHILLS AND
PALMER DIVIDE FOR THE MAIN AREA OF PRECIP. CONFIDENCE HAS IMPROVED
ENOUGH TO GO WITH LIKELY POPS ACROSS PORTIONS OF ZONE 38 AND
41...INCLUDING FOOTHILL LOCATIONS BETWEEN 21Z AND 03Z.
ACCUMULATIONS STILL LOOK TO BE LESS THAN AN INCH. REST OF
FORECASTS SEEM ON TRACK FOR NOW.
AVIATION...STILL SOME STRATUS ALONG LOW LYING AREAS OF SOUTHERN
WELD COUNTY...SHOULD REMAIN IN THAT AREA AND NOT AFFECT THE
AIRPORTS. WINDS SHOWING MORE OF A SOUTHEAST COMPONENT. STILL SOME
CHANCE OF LIGHT SNOW BETWEEN 23Z AND 06Z. HOWEVER HAVE A LOW
CONFIDENCE IN A TEMPO GROUP AT THIS TIME AND WILL KEEP THE VCSH
WITH PERHAPS A PROB030 AFTER 03Z. WILL CONTINUE THE TREND OF THE
CURRENT TAFS AT THIS POINT. IF SNOW DOES AFFECT THE AREA
AIRPORTS...ACCUMULATIONS SHOULD BE LESS THAN AN INCH.
PREV DISCUSSION... /ISSUED 259 AM MST THU DEC 27 2012/
SHORT TERM...A BROAD CIRCULATION CENTER WAS LOCATED FM ERN WY
INTO WRN NE EARLY THIS MORNING AND WILL MOVE SLOWLY EASTWARD THRU
TONIGHT. OVERALL THE FLOW ALOFT IN THE MTNS WILL BE WNW WITH
FAVORABLE OROGRAPHICS THRU TONIGHT. LAPSE RATES WILL AVERAGE
AROUND 7 C/KM WITH MOISTURE DEPTH AROUND 300 MB SO SHOULD SEE
PERIODS OF SNOW WITH ACCUMULATIONS MEETING ADVISORY CRITERIA. OVER
NERN CO IT APPEARS ANY PCPN THRU LATE AFTN WILL BE CONFINED TO
THE FAR NERN CORNER MAINLY THIS MORNING. HOWEVER BY THIS EVENING A
DISTURBANCE WILL MOVE SSE ACROSS THE AREA WITH WEAK UPSLOPE FLOW
DEVELOPING ALONG THE FRONT RANGE. THUS COULD SEE A BREIF PERIOD OF
LIGHT SNOW IN AND NR THE FOOTHILLS AND OVER THE PALMER DIVIDE IN
THE 00Z-06Z TIMEFRAME. HAVE INCREASED POPS TO CHC CATEGORY HOWEVER
CONFIDENCE IS NOT HIGH ENOUGH AT THIS POINT TO GO LIKELY. AS FAR
AS HIGHS THIS AFTN READINGS ACROSS NERN CO WILL BE MAINLY IN THE
20S. AROUND DENVER COULD SEE A 10 DEGREE SPREAD IN HIGHS AS
INVERSION MAY BREAK OVER THE SRN SUBURBS ALLOWING FOR HIGHS IN
THE LOWER TO MID 30S WHILE OTHER AREAS AROUND DENVER STAY IN THE
MID TO UPPER 20S.
LONG TERM...ZONAL FLOW IS PROGGED OVER THE CWA FRIDAY...THEN
NORTHWESTERLY FLOW ALOFT IS PROGGED FOR FRIDAY NIGHT. AN UPPER
RIDGE IS PROGGED TO MOVE ACROSS COLORADO SATURDAY. THE FLOW ALOFT
IS ZONAL ON SATURDAY...THEN SOUTHWESTERLY SATURDAY NIGHT. THE QG
VERTICAL VELOCITY FIELDS HAVE DOWNWARD SYNOPTIC SCALE ENERGY OVER
THE CWA FRIDAY INTO SATURDAY MORNING. THE REST OF SATURDAY AND
SATURDAY NIGHT HAS WEAK UPWARD MOTION PROGGED. THE BOUNDARY LAYER
FLOW LOOKS TO BE DOMINATED BY DOWNSLOPING FRIDAY INTO SATURDAY
MORNING...THEN MORE NORMAL DUIRNAL PATTERNS ARE PROGGED FOR THE
REST OF SATURDAY AND SATURDAY NIGHT. FOR MOISTURE...THERE IS SOME
AROUND ON FRIDAY...ACTUALLY PRETTY DEEP OVER THE MOUNTAINS IN THE
MORNING. DRYING KICKS IN BY AFTERNOON...CONTINUING FRIDAY
EVENING. THE REST OF FRIDAY NIGHT AND SATURDAY LOOK PRETTY DRY FOR
ALL AREAS...MAYBE SOME HIGH CLOUDS. MOISTURE INCREASES SATURDAY
NIGHT...MOSTLY THE UPPER LEVEL TYPE. THE QPF FIELDS SHOW SMALL
AMOUNTS OF MEASURABLE PRECIPITATION ON FRIDAY IN THE MOUNTAINS
ONLY. FRIDAY NIGHT THROUGH SATURDAY NIGHT ARE DRY. SO FOR POPS
.WILL GO WITH 30-60%S IN THE MOUNTAINS ON FRIDAY. THERE IS
FAIRLY DECENT MOISTURE AND SOME HELP FROM OROGRAPHICS. JUST MINOR
POPS IN THE MOUNTAINS FRIDAY EVENING. NO POPS ELSEWHERE THROUGH
THE PERIODS. FOR TEMPERATURES...FRIDAY`S HIGHS ARE A TAD WARMER
THAN TODAY`S. SATURDAY`S WARM UP 2-4 C FROM FIRDAY`S HIGHS. FOR
THE LATER DAYS...SUNDAY THROUGH WEDNESDAY...SOUTHWESTERLY FLOW
ALOFT IS PROGGED SUNDAY INTO MONDAY. MODELS SHOW AN UPPER TROUGH
TO MOVE ACROSS THE FORECAST AREA LATE MONDAY INTO TUESDAY MORNING.
THE ECMWF AND GFS SHOW THE TROUGH IN PRETTY FAIR AGREEMENT.
HOWEVER...THE ECMWF HAS A CLOSED CIRCULATION AT IT`S BASE...THE
GFS DOES NOT HAVE THIS. SO BY TUESDAY...THE GFS HAS THE TROUGH
THROUGH THE CWA...WHILE THE ECMWF HAS A CLOSED CIRCULATION SOUTH
OF COLORADO. THIS UPPER LOW IS CENTERED NEAR EL PASO TEXAS LATE
WEDNESDAY. MOISTURE IS WAY DIFFERENT ON THE TWO MODELS....THE GFS
SHOWS QUITE A BIT OF MOISTURE FOR SUNDAY NIGHT AND MONDAY. THE
ECMWF DOWSN`T GET MOISTURE INTO THE CWA UNTIL MONDAY NIGHT AND
TUESDAY. POOR AGREEMENT HERE. LATER TUESDAY THROUGH WEDNESDAY LOOK
DRY ON BOTH MODELS. WILL KEEP POPS SOMEWHAT AT BAY DUE TO THE
UNCERTAINTIES.
AVIATION...STRATUS HAS REMAINED JUST TO THE NORTH OF THE AIRPORT OVER
SRN WELD COUNTY THE ENTIRE NIGHT AND SO FAR HAS SHOWN NO SIGNS OF
SPREADING SOUTH AT THIS POINT. BOTH THE RAP AND THE HRRR KEEP SHOW
SFC WINDS BECOMING MORE SLY BY SUNRISE SO IF THAT OCCURS THEN
STRATUS MAY NOT AFFECT THE AIRPORT. COULD SEE SOME PATCHY FOG
HOWEVER VISBILITIES LOOK TO BE AOA 5 MILES AT THIS POINT. BY
MIDDAY SFC WINDS WILL BECOME MORE ELY AND STAY THAT WAY THRU EARLY
EVENING. AS TALKED ABOUT ABV THERE COULD BE SOME LIGHT SNOW FOR A
FEW HOURS BETWEEN 00Z AND 06Z AS DISTURBANCE MOVES SSE ACROSS THE
AREA. AT THIS POINT ANY ACCUMULATION SHOULD BE LESS THAN AN INCH
IF SNOW DEVELOPS.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 11 PM MST THIS EVENING FOR COZ031-
033-034.
&&
$$
SHORT TERM...D-L
LONG TERM....MEIER
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS PUEBLO CO
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.
&&
$$
31/34
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1208 PM MST THU DEC 27 2012
.UPDATE...
ISSUED AT 1208 PM MST THU DEC 27 2012
DEFORMATION AXIS ALONG THE SRN WY BORDER WAS EVIDIENT ON INFRARED
SATELLITE THIS MORNING...BUT WARMING CLOUD TOPS INDICATIVE OF THIS
FEATURE BEGINNING TO WEAKEN. RAP40 MODEL SHOWS THIS WEAKENING
TREND FOR THE AFTERNOON AS THE AXIS DRIFTS SLOWLY SOUTH. STILL EXPECT
IT PLUS WEAK OROGRAPHIC FORCING AS FLOW BECOMES MORE NORTHWEST TO
KEEP OCCASIONAL SNOW ACROSS NW CO THROUGH THIS EVENING.
MID-MORNING SPOTTER AND SNOTEL REPORTS INDICATED ROUGHLY 4-8 INCHES
OF NEW SNOW ACROSS THE ELKHEAD/PARK/GORE RANGES AND FLATTOPS.
LOCATIONS SUCH AS TOWER SNOTEL AND STEAMBOAT SKI REPORTED 15-17
INCHES...BUT THESE APPEAR TO BE THE EXCEPTIONS RATHER THAN THE NORM.
THUS...WILL NOT UPGRADE THE CURRENT ADVISORIES FOR THE NRN CO MTNS
BUT WILL INCREASE TOTAL ACCUMS TO 7-14 INCHES WITH LOCALLY HIGHER
AMOUNTS IN A MIDDAY UPDATE TO THE ADVISORY STATEMENT.
MID-MORNING SPOTTER REPORTS INDICATED ROUGHLY 2-4 INCHES ACROSS THE
NW CO PLATEAU WITH LOCALLY HIGHER AMOUNTS AROUND 6 INCHES IN THE
MEEKER AND RANGELY AREAS. ABOUT 8 INCHES REPORTED FOR STEAMBOAT
TOWN. WILL CONTINUE WITH THE CURRENT ADVISORIES FOR THESE AREAS.
SNOW AND CLOUDS ARE EXPECTED TO SPREAD BACK ACROSS THE CENTRALA ND
SOUTHWESTERN CO MTNS THIS AFTERNOON AS THE COLD AND MOIST AIRMASS
SLOWLY ROTATES THROUGH THE TROUGH AND AROUND AN UPPER LOW OVER
NE/SD. SOME MORNING SUNSHINE LIKLEY ADDED SOME LOW LEVEL INSTABILITY.
UPDATE ISSUED AT 904 AM MST THU DEC 27 2012
ALLOWED THE WINTER WEATHER ADVISORIES FOR THE ERN UINTA BASIN AS
WELL AS THE CENTRAL AND SOUTHERN VALLEYS TO EXPIRE NORMALLY AT 9
AM THIS MORNING. COLD AND MOIST AIRMASS REMAINING OVER THE AREA
UNDER A BROAD TROUGH OVERHEAD AND WILL STILL KEEP SOME LIGHT SNOW
OR SNOW SHOWERS IN THE VALLEYS...BUT DO NOT EXPECT MUCH MORE
ACCUMULATION...ALTHOUGH MAY STILL SEE SOME LOCALIZED ACCUMS IN THE
ERN UINTA BASIN WHICH APPEARS TO BE UNDER A WEAK DEFORMATION AXIS
THAT EXTENDS ACROSS NW CO TO AN UPPER LOW OVER WRN NEBRASKA.
OCCASIONAL SNOW WILL CONTINUE OVER THE MOUNTAINS AND THE NW CO
PLATEAU AS FLOW SHIFTS FROM WEST THIS MORNING TO NORTHWEST THIS
AFTERNOON...AND WILL KEEP THOSE ADVISORIES IN FORCE. WEBCAMS
SHOWED BREAKS IN THE CLOUDS ACROSS THE SAN JUANS AND THE SOUTH
THIS MORNING...BUT HI-RESOLUTION HRRR MODEL INDICATES THIS TO FILL
BACK IN THIS AFTERNOON AS THE NEXT DISTURBANCE ROTATES THROUGH.
HAVE UPDATED THE WORDED AND FORECAST GRIDS TO REFLECT THIS
THINKING.
&&
.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 346 AM MST THU DEC 27 2012
A MESSY DISORGANIZED COLD WINTER STORM CONTINUES TO PRODUCE
WIDESPREAD BUT LIGHT SNOWFALL ACROSS THE FORECAST AREA. KEY TO THE
SNOW PRODUCTION IS A MOIST DENDRITIC GROWTH LAYER AT 700 TO 600MB
OR THE MTN TOP LAYER. DEVELOPING MID LEVEL CYCLONIC FLOW AND A
SHOT OF COLD ADVECTION TODAY WILL ALSO KEEP SNOW PRODUCTION
WIDESPREAD.
THE MAIN SYNOPTIC FEATURE IS THE CLOSED LOW OVER EASTERN WYOMING
THAT IS ROTATING SPOKES OF ENERGY MAINLY ACROSS THE NORTHERN
ZONES. THIS LOW WILL SHIFT EAST THIS MORNING WITH THE LAST
TRAILING DISTURBANCE AND SHOT OF COLD AIR ROTATING OVER THE
NORTHERN COLORADO MTNS. IN ADDITION THE 500-300MB SHEAR AXIS
REMAINS OVER THE SW SAN JUAN REGION THROUGH THE MORNING HOURS.
SANDWICHED BETWEEN THESE TWO LARGER SCALE FEATURES...THE CENTRAL
ZONES ARE ACCUMULATING THE LEAST SNOW AMOUNTS. IT WILL BE
DIFFICULT FOR GRAND JUNCTION AND MONTROSE TO ACCUMULATE 3 INCHES
OF SNOW...BUT WITH SNOWFALL CONTINUING WILL KEEP THE ADVISORIES
ACTIVE. OTHERWISE THE VEERING WINDS ALOFT FROM WEST TO NORTH WILL
PRODUCE SNOWFALL MAINLY ON NORTH FACING SLOPES WHERE SKI SLOPES
ARE LOCATED. THE CENTRAL VALLEYS COULD ALSO SEE A QUICK FEW INCHES
OF SNOWFALL IN THE LATE AFTERNOON INTO THE EARLY EVENING.
TONIGHT...NORTH FLOW CONTINUES WITH WEAK TRANSIENT RIDGING
BUILDING AFTER MIDNIGHT. IN SPITE OF THIS...LIGHT OROGRAPHIC
SNOWFALL IS EXPECTED FAVORING THE NORTHERN MTNS. FRIDAY...A DRIER
AIR MASS WORKS IN FROM WEST TO EAST WITH LIGHT SNOWFALL CONTINUING
ONLY IN THE EASTERN MTNS. WARM ADVECTION ALOFT BEGINS IN THE
AFTERNOON STRONGLY CAPPING THE COLD AIR IN THE VALLEYS.
.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 346 AM MST THU DEC 27 2012
SNOW COMES TO AN END OVER THE ENTIRE FORECAST AREA FRIDAY NIGHT AS
SHRTWV RIDGE WORKS EAST. THIS WILL BRING DRY CONDITIONS THROUGH
EARLY SUNDAY...BEFORE NEXT LONG WAVE TROUGH WORKS INTO THE WESTERN
U.S. MEDIUM RANGE MODELS STILL ON DIFFERENT PATHS IN REGARDS TO
THIS SPLITTING SYSTEM WITH THE ECMWF CONTINUING TO DRIVE THE
SOUTHERN EXTENT OF THE TROUGH SOUTH INTO THE BAJA REGION BY
SUNDAY...WITH SPLITTING NORTHERN ENERGY SLOWLY DROPPING SOUTHWEST
ACROSS THE WESTERN GREAT BASIN AND EVENTUALLY PHASING WITH THE
SOUTHERN STREAM...THEN EJECTING OUT BY MIDWEEK. THIS KEEPS PRECIP
OUT OF OUR REGION UNTIL LATER MONDAY WITH MAIN IMPACT ACROSS THE
SOUTHERN ZONES.
THE GFS ON THE OTHER HAND SPLITS THE TROUGH AS WELL...BUT FOCUS IS
ON THE NORTHERN STREAM WHICH DRIVES THROUGH THE FORECAST AREA AS A
POSITIVELY TILTED TROUGH SUNDAY NIGHT AND MONDAY...WHICH WOULD
BRING A GOOD CHANCE OF SNOW TO MUCH OF THE FORECAST AREA.
WITH THESE TWO OUT OF PHASE...DECIDED TO TAKE A CLOSER LOOK AT THE
CANADIAN AND OTHER ENSEMBLES AVAILABLE WHICH OFFERING MORE OF A
COMPROMISE BETWEEN THE TWO. SO WILL KEEP LOW POPS IN THE FORECAST
BEGINNING AS EARLY AS SUNDAY AFTERNOON AND PEAKING ON MONDAY. THE
GFS HAS MAINTAINED SOME CONSISTENCY OVER THE PAST FEW RUNS...SO
SOME INCREASE IN CONFIDENCE TOWARD THAT SOLUTION...BUT NOT ENOUGH
TO DRIVE POPS INTO THE LIKELY THRESHOLD.
BEYOND THIS EVENT...THE FORECAST REMAINS RATHER UNSETTLED WITH
ANOTHER FAST MOVING SYSTEM RUNNING THROUGH TUESDAY
AFTERNOON...FOLLOWED BY TRANSITORY RIDGING AT MIDWEEK WITH YET
ANOTHER SYSTEM POSSIBLE BY THE END OF THE WEEK.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 955 AM MST THU DEC 27 2012
SNOWFALL WILL RESULT IN MOUNTAIN OBSCURATIONS...AND MVFR CIGS AND
VSBY FOR THE NORTHERN AIRPORTS. IFR VSBY WILL BE POSSIBLE AT TIMES
IN HEAVIER SNOW. ALONG AND SOUTH OF I-70 SNOWFALL WILL GENERALLY
BE LIGHTER AND MORE SPORADIC. EXPECT PERIODS OF MVFR/ISOLD IFR
CONDITIONS THROUGH TODAY. WHILE CLOUD DECKS AT KEGE AND KRIL HAVE
OPENED UP THIS MORNING...CLOUDS WILL AGAIN INCREASE AND THICKEN
THIS AFTERNOON WITH SNOW SHOWERS DEVELOPING. THE FLOW TURNS TO
COLD NW THIS AFTERNOON AND EVENING WITH WIDESPREAD SNOWFALL ALONG
NORTH AND NORTHWEST FACING SLOPES THROUGH TONIGHT. OTHERWISE
IMPROVING CONDITIONS ARE EXPECTED. THESE OROGRAPHIC SNOW SHOWERS
WILL DIMINISH EARLY FRIDAY. AREAS OF FOG MAY RESULT IN MVFR OR IFR
CONDITIONS AT AREA AIRPORTS LATE TONIGHT AND FRIDAY MORNING.
&&
.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...JAD
SHORT TERM...JOE
LONG TERM...JDC
AVIATION...EH
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1007 AM MST THU DEC 27 2012
.UPDATE...
&&
.SHORT TERM...MOUNTAIN WEB CAMS SHOWING SNOW ACROSS MUCH OF THE
REGION. WITH MOIST WEST NORTHWEST FLOW ALONG TO PERSIST THROUGH
MUCH OF THE DAY ALONG WITH LAPSE RATES AROUND 6 C/KM WEAK MID
LEVEL QG ASCENT...SNOW SHOULD CONTINUE INTO THE EVENING WITH
ANOTHER 3-6 INCHES. CURRENT ADVISORIES TO CONTINUE. SOME DECREASE
IN THE SNOW STILL EXPECTED OVERNIGHT AS ASCENT WEAKENS AND
SUBSIDENCE PREVAILS. ACROSS PLAINS...THE LIGHT SNOW OVER THE
NORTHEAST CORNER HAS ENDED WITH MOSTLY CLOUDY CONDITIONS
PREVAILING. LATEST MODELS CONTINUE TO SHOW WEAK DISTURBANCE MOVING
ACROSS THE CENTRAL PLAINS WITH WEAK UPSLOPE LOW DEVELOPING ALONG
THE FRONT RANGE. RAP/RUC SHOW SOME LIGHT PRECIP/QPF DEVELOPING
ACROSS THE NORTHERN FRONT RANGE AND PALMER DIVIDE AREA DURING THE
AFTERNOON WITH THE NORTHERN BATCH GRADUALLY SPREADING SOUTHWARD
BY EVENING. THERE STILL IS THE POTENTIAL FOR SOME LIGHT SNOW IN
AND NEAR THE FRONT RANGE. LATEST MODELS SEEM TO FAVOR THE NORTHERN
PORTIONS OF THE FRONT RANGE AS WELL AS NEAR THE FOOTHILLS AND
PALMER DIVIDE FOR THE MAIN AREA OF PRECIP. CONFIDENCE HAS IMPROVED
ENOUGH TO GO WITH LIKELY POPS ACROSS PORTIONS OF ZONE 38 AND
41...INCLUDING FOOTHILL LOCATIONS BETWEEN 21Z AND 03Z.
ACCUMULATIONS STILL LOOK TO BE LESS THAN AN INCH. REST OF
FORECASTS SEEM ON TRACK FOR NOW.
.AVIATION...STILL SOME STRATUS ALONG LOW LYING AREAS OF SOUTHERN
WELD COUNTY...SHOULD REMAIN IN THAT AREA AND NOT AFFECT THE
AIRPORTS. WINDS SHOWING MORE OF A SOUTHEAST COMPONENT. STILL SOME
CHANCE OF LIGHT SNOW BETWEEN 23Z AND 06Z. HOWEVER HAVE A LOW
CONFIDENCE IN A TEMPO GROUP AT THIS TIME AND WILL KEEP THE VCSH
WITH PERHAPS A PROB030 AFTER 03Z. WILL CONTINUE THE TREND OF THE
CURRENT TAFS AT THIS POINT. IF SNOW DOES AFFECT THE AREA
AIRPORTS...ACCUMULATIONS SHOULD BE LESS THAN AN INCH.
&&
.PREV DISCUSSION... /ISSUED 259 AM MST THU DEC 27 2012/
SHORT TERM...A BROAD CIRCULATION CENTER WAS LOCATED FM ERN WY
INTO WRN NE EARLY THIS MORNING AND WILL MOVE SLOWLY EASTWARD THRU
TONIGHT. OVERALL THE FLOW ALOFT IN THE MTNS WILL BE WNW WITH
FAVORABLE OROGRAPHICS THRU TONIGHT. LAPSE RATES WILL AVERAGE
AROUND 7 C/KM WITH MOISTURE DEPTH AROUND 300 MB SO SHOULD SEE
PERIODS OF SNOW WITH ACCUMULATIONS MEETING ADVISORY CRITERIA. OVER
NERN CO IT APPEARS ANY PCPN THRU LATE AFTN WILL BE CONFINED TO
THE FAR NERN CORNER MAINLY THIS MORNING. HOWEVER BY THIS EVENING A
DISTURBANCE WILL MOVE SSE ACROSS THE AREA WITH WEAK UPSLOPE FLOW
DEVELOPING ALONG THE FRONT RANGE. THUS COULD SEE A BREIF PERIOD OF
LIGHT SNOW IN AND NR THE FOOTHILLS AND OVER THE PALMER DIVIDE IN
THE 00Z-06Z TIMEFRAME. HAVE INCREASED POPS TO CHC CATEGORY HOWEVER
CONFIDENCE IS NOT HIGH ENOUGH AT THIS POINT TO GO LIKELY. AS FAR
AS HIGHS THIS AFTN READINGS ACROSS NERN CO WILL BE MAINLY IN THE
20S. AROUND DENVER COULD SEE A 10 DEGREE SPREAD IN HIGHS AS
INVERSION MAY BREAK OVER THE SRN SUBURBS ALLOWING FOR HIGHS IN
THE LOWER TO MID 30S WHILE OTHER AREAS AROUND DENVER STAY IN THE
MID TO UPPER 20S.
LONG TERM...ZONAL FLOW IS PROGGED OVER THE CWA FRIDAY...THEN
NORTHWESTERLY FLOW ALOFT IS PROGGED FOR FRIDAY NIGHT. AN UPPER
RIDGE IS PROGGED TO MOVE ACROSS COLORADO SATURDAY. THE FLOW ALOFT
IS ZONAL ON SATURDAY...THEN SOUTHWESTERLY SATURDAY NIGHT. THE QG
VERTICAL VELOCITY FIELDS HAVE DOWNWARD SYNOPTIC SCALE ENERGY OVER
THE CWA FRIDAY INTO SATURDAY MORNING. THE REST OF SATURDAY AND
SATURDAY NIGHT HAS WEAK UPWARD MOTION PROGGED. THE BOUNDARY LAYER
FLOW LOOKS TO BE DOMINATED BY DOWNSLOPING FRIDAY INTO SATURDAY
MORNING...THEN MORE NORMAL DUIRNAL PATTERNS ARE PROGGED FOR THE
REST OF SATURDAY AND SATURDAY NIGHT. FOR MOISTURE...THERE IS SOME
AROUND ON FRIDAY...ACTUALLY PRETTY DEEP OVER THE MOUNTAINS IN THE
MORNING. DRYING KICKS IN BY AFTERNOON...CONTINUING FRIDAY
EVENING. THE REST OF FRIDAY NIGHT AND SATURDAY LOOK PRETTY DRY FOR
ALL AREAS...MAYBE SOME HIGH CLOUDS. MOISTURE INCREASES SATURDAY
NIGHT...MOSTLY THE UPPER LEVEL TYPE. THE QPF FIELDS SHOW SMALL
AMOUNTS OF MEASURABLE PRECIPITATION ON FRIDAY IN THE MOUNTAINS
ONLY. FRIDAY NIGHT THROUGH SATURDAY NIGHT ARE DRY. SO FOR POPS
..WILL GO WITH 30-60%S IN THE MOUNTAINS ON FRIDAY. THERE IS
FAIRLY DECENT MOISTURE AND SOME HELP FROM OROGRAPHICS. JUST MINOR
POPS IN THE MOUNTAINS FRIDAY EVENING. NO POPS ELSEWHERE THROUGH
THE PERIODS. FOR TEMPERATURES...FRIDAY`S HIGHS ARE A TAD WARMER
THAN TODAY`S. SATURDAY`S WARM UP 2-4 C FROM FIRDAY`S HIGHS. FOR
THE LATER DAYS...SUNDAY THROUGH WEDNESDAY...SOUTHWESTERLY FLOW
ALOFT IS PROGGED SUNDAY INTO MONDAY. MODELS SHOW AN UPPER TROUGH
TO MOVE ACROSS THE FORECAST AREA LATE MONDAY INTO TUESDAY MORNING.
THE ECMWF AND GFS SHOW THE TROUGH IN PRETTY FAIR AGREEMENT.
HOWEVER...THE ECMWF HAS A CLOSED CIRCULATION AT IT`S BASE...THE
GFS DOES NOT HAVE THIS. SO BY TUESDAY...THE GFS HAS THE TROUGH
THROUGH THE CWA...WHILE THE ECMWF HAS A CLOSED CIRCULATION SOUTH
OF COLORADO. THIS UPPER LOW IS CENTERED NEAR EL PASO TEXAS LATE
WEDNESDAY. MOISTURE IS WAY DIFFERENT ON THE TWO MODELS....THE GFS
SHOWS QUITE A BIT OF MOISTURE FOR SUNDAY NIGHT AND MONDAY. THE
ECMWF DOWSN`T GET MOISTURE INTO THE CWA UNTIL MONDAY NIGHT AND
TUESDAY. POOR AGREEMENT HERE. LATER TUESDAY THROUGH WEDNESDAY LOOK
DRY ON BOTH MODELS. WILL KEEP POPS SOMEWHAT AT BAY DUE TO THE
UNCERTAINTIES.
AVIATION...STRATUS HAS REMAINED JUST TO THE NORTH OF THE AIRPORT OVER
SRN WELD COUNTY THE ENTIRE NIGHT AND SO FAR HAS SHOWN NO SIGNS OF
SPREADING SOUTH AT THIS POINT. BOTH THE RAP AND THE HRRR KEEP SHOW
SFC WINDS BECOMING MORE SLY BY SUNRISE SO IF THAT OCCURS THEN
STRATUS MAY NOT AFFECT THE AIRPORT. COULD SEE SOME PATCHY FOG
HOWEVER VISBILITIES LOOK TO BE AOA 5 MILES AT THIS POINT. BY
MIDDAY SFC WINDS WILL BECOME MORE ELY AND STAY THAT WAY THRU EARLY
EVENING. AS TALKED ABOUT ABV THERE COULD BE SOME LIGHT SNOW FOR A
FEW HOURS BETWEEN 00Z AND 06Z AS DISTURBANCE MOVES SSE ACROSS THE
AREA. AT THIS POINT ANY ACCUMULATION SHOULD BE LESS THAN AN INCH
IF SNOW DEVELOPS.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 11 PM MST THIS EVENING FOR COZ031-
033-034.
&&
$$
SHORT TERM...D-L
LONG TERM....RJK
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
955 AM MST THU DEC 27 2012
.UPDATE...
ISSUED AT 904 AM MST THU DEC 27 2012
ALLOWED THE WINTER WEATHER ADVISORIES FOR THE ERN UINTA BASIN AS
WELL AS THE CENTRAL AND SOUTHERN VALLEYS TO EXPIRE NORMALLY AT 9
AM THIS MORNING. COLD AND MOIST AIRMASS REMAINING OVER THE AREA
UNDER A BROAD TROUGH OVERHEAD AND WILL STILL KEEP SOME LIGHT SNOW
OR SNOW SHOWERS IN THE VALLEYS...BUT DO NOT EXPECT MUCH MORE
ACCUMULATION...ALTHOUGH MAY STILL SEE SOME LOCALIZED ACCUMS IN THE
ERN UINTA BASIN WHICH APPEARS TO BE UNDER A WEAK DEFORMATION AXIS
THAT EXTENDS ACROSS NW CO TO AN UPPER LOW OVER WRN NEBRASKA.
OCCASIONAL SNOW WILL CONTINUE OVER THE MOUNTAINS AND THE NW CO
PLATEAU AS FLOW SHIFTS FROM WEST THIS MORNING TO NORTHWEST THIS
AFTERNOON...AND WILL KEEP THOSE ADVISORIES IN FORCE. WEBCAMS
SHOWED BREAKS IN THE CLOUDS ACROSS THE SAN JUANS AND THE SOUTH
THIS MORNING...BUT HI-RESOLUTION HRRR MODEL INDICATES THIS TO FILL
BACK IN THIS AFTERNOON AS THE NEXT DISTURBANCE ROTATES THROUGH.
HAVE UPDATED THE WORDED AND FORECAST GRIDS TO REFLECT THIS
THINKING.
&&
.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 346 AM MST THU DEC 27 2012
A MESSY DISORGANIZED COLD WINTER STORM CONTINUES TO PRODUCE
WIDESPREAD BUT LIGHT SNOWFALL ACROSS THE FORECAST AREA. KEY TO THE
SNOW PRODUCTION IS A MOIST DENDRITIC GROWTH LAYER AT 700 TO 600MB
OR THE MTN TOP LAYER. DEVELOPING MID LEVEL CYCLONIC FLOW AND A
SHOT OF COLD ADVECTION TODAY WILL ALSO KEEP SNOW PRODUCTION
WIDESPREAD.
THE MAIN SYNOPTIC FEATURE IS THE CLOSED LOW OVER EASTERN WYOMING
THAT IS ROTATING SPOKES OF ENERGY MAINLY ACROSS THE NORTHERN
ZONES. THIS LOW WILL SHIFT EAST THIS MORNING WITH THE LAST
TRAILING DISTURBANCE AND SHOT OF COLD AIR ROTATING OVER THE
NORTHERN COLORADO MTNS. IN ADDITION THE 500-300MB SHEAR AXIS
REMAINS OVER THE SW SAN JUAN REGION THROUGH THE MORNING HOURS.
SANDWICHED BETWEEN THESE TWO LARGER SCALE FEATURES...THE CENTRAL
ZONES ARE ACCUMULATING THE LEAST SNOW AMOUNTS. IT WILL BE
DIFFICULT FOR GRAND JUNCTION AND MONTROSE TO ACCUMULATE 3 INCHES
OF SNOW...BUT WITH SNOWFALL CONTINUING WILL KEEP THE ADVISORIES
ACTIVE. OTHERWISE THE VEERING WINDS ALOFT FROM WEST TO NORTH WILL
PRODUCE SNOWFALL MAINLY ON NORTH FACING SLOPES WHERE SKI SLOPES
ARE LOCATED. THE CENTRAL VALLEYS COULD ALSO SEE A QUICK FEW INCHES
OF SNOWFALL IN THE LATE AFTERNOON INTO THE EARLY EVENING.
TONIGHT...NORTH FLOW CONTINUES WITH WEAK TRANSIENT RIDGING
BUILDING AFTER MIDNIGHT. IN SPITE OF THIS...LIGHT OROGRAPHIC
SNOWFALL IS EXPECTED FAVORING THE NORTHERN MTNS. FRIDAY...A DRIER
AIR MASS WORKS IN FROM WEST TO EAST WITH LIGHT SNOWFALL CONTINUING
ONLY IN THE EASTERN MTNS. WARM ADVECTION ALOFT BEGINS IN THE
AFTERNOON STRONGLY CAPPING THE COLD AIR IN THE VALLEYS.
.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 346 AM MST THU DEC 27 2012
SNOW COMES TO AN END OVER THE ENTIRE FORECAST AREA FRIDAY NIGHT AS
SHRTWV RIDGE WORKS EAST. THIS WILL BRING DRY CONDITIONS THROUGH
EARLY SUNDAY...BEFORE NEXT LONG WAVE TROUGH WORKS INTO THE WESTERN
U.S. MEDIUM RANGE MODELS STILL ON DIFFERENT PATHS IN REGARDS TO
THIS SPLITTING SYSTEM WITH THE ECMWF CONTINUING TO DRIVE THE
SOUTHERN EXTENT OF THE TROUGH SOUTH INTO THE BAJA REGION BY
SUNDAY...WITH SPLITTING NORTHERN ENERGY SLOWLY DROPPING SOUTHWEST
ACROSS THE WESTERN GREAT BASIN AND EVENTUALLY PHASING WITH THE
SOUTHERN STREAM...THEN EJECTING OUT BY MIDWEEK. THIS KEEPS PRECIP
OUT OF OUR REGION UNTIL LATER MONDAY WITH MAIN IMPACT ACROSS THE
SOUTHERN ZONES.
THE GFS ON THE OTHER HAND SPLITS THE TROUGH AS WELL...BUT FOCUS IS
ON THE NORTHERN STREAM WHICH DRIVES THROUGH THE FORECAST AREA AS A
POSITIVELY TILTED TROUGH SUNDAY NIGHT AND MONDAY...WHICH WOULD
BRING A GOOD CHANCE OF SNOW TO MUCH OF THE FORECAST AREA.
WITH THESE TWO OUT OF PHASE...DECIDED TO TAKE A CLOSER LOOK AT THE
CANADIAN AND OTHER ENSEMBLES AVAILABLE WHICH OFFERING MORE OF A
COMPROMISE BETWEEN THE TWO. SO WILL KEEP LOW POPS IN THE FORECAST
BEGINNING AS EARLY AS SUNDAY AFTERNOON AND PEAKING ON MONDAY. THE
GFS HAS MAINTAINED SOME CONSISTENCY OVER THE PAST FEW RUNS...SO
SOME INCREASE IN CONFIDENCE TOWARD THAT SOLUTION...BUT NOT ENOUGH
TO DRIVE POPS INTO THE LIKELY THRESHOLD.
BEYOND THIS EVENT...THE FORECAST REMAINS RATHER UNSETTLED WITH
ANOTHER FAST MOVING SYSTEM RUNNING THROUGH TUESDAY
AFTERNOON...FOLLOWED BY TRANSITORY RIDGING AT MIDWEEK WITH YET
ANOTHER SYSTEM POSSIBLE BY THE END OF THE WEEK.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 955 AM MST THU DEC 27 2012
SNOWFALL WILL RESULT IN MOUNTAIN OBSCURATIONS...AND MVFR CIGS AND
VSBY FOR THE NORTHERN AIRPORTS. IFR VSBY WILL BE POSSIBLE AT TIMES
IN HEAVIER SNOW. ALONG AND SOUTH OF I-70 SNOWFALL WILL GENERALLY
BE LIGHTER AND MORE SPORADIC. EXPECT PERIODS OF MVFR/ISOLD IFR
CONDITIONS THROUGH TODAY. WHILE CLOUD DECKS AT KEGE AND KRIL HAVE
OPENED UP THIS MORNING...CLOUDS WILL AGAIN INCREASE AND THICKEN
THIS AFTERNOON WITH SNOW SHOWERS DEVELOPING. THE FLOW TURNS TO
COLD NW THIS AFTERNOON AND EVENING WITH WIDESPREAD SNOWFALL ALONG
NORTH AND NORTHWEST FACING SLOPES THROUGH TONIGHT. OTHERWISE
IMPROVING CONDITIONS ARE EXPECTED. THESE OROGRAPHIC SNOW SHOWERS
WILL DIMINISH EARLY FRIDAY. AREAS OF FOG MAY RESULT IN MVFR OR IFR
CONDITIONS AT AREA AIRPORTS LATE TONIGHT AND FRIDAY MORNING.
&&
.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...JAD
SHORT TERM...JOE
LONG TERM...JDC
AVIATION...EH
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
906 AM MST THU DEC 27 2012
.UPDATE...
ISSUED AT 904 AM MST THU DEC 27 2012
ALLOWED THE WINTER WEATHER ADVISORIES FOR THE ERN UINTA BASIN AS WELL
AS THE CENTRAL AND SOUTHERN VALLEYS TO EXPIRE NORMALLY AT 9 AM
THIS MORNING. COLD AND MOIST AIRMASS REMAINING OVER THE AREA UNDER
A BROAD TROUGH OVERHEAD AND WILL STILL KEEP SOME LIGHT SNOW OR
SNOW SHOWERS IN THE VALLEYS...BUT DO NOT EXPECT MUCH MORE
ACCUMULATION...ALTHOUGH MAY STILL SEE SOME LOCALIZED ACCUMS IN
THE ERN UINTA BASIN WHICH APPEARS TO BE UNDER A WEAK DEFORMATION
AXIS THAT EXTENDS ACROSS NW CO TO AN UPPER LOW OVER WRN NEBRASKA.
OCCASIONAL SNOW WILL CONTINUE OVER THE MOUNTAINS AND THE NW CO
PLATEAU AS FLOW SHIFTS FROM WEST THIS MORNING TO NORTHWEST THIS
AFTERNOON...AND WILL KEEP THOSE ADVISORIES IN FORCE. WEBCAMS
SHOWED BREAKS IN THE CLOUDS ACROSS THE SAN JUANS AND THE SOUTH
THIS MORNING...BUT HI-RESOLUTION HRRR MODEL INDICATES THIS TO
FILL BACK IN THIS AFTERNOON AS THE NEXT DISTURBANCE ROTATES
THROUGH. HAVE UPDATED THE WORDED AND FORECAST GRIDS TO REFLECT
THIS THINKING.
&&
.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 346 AM MST THU DEC 27 2012
A MESSY DISORGANIZED COLD WINTER STORM CONTINUES TO PRODUCE
WIDESPREAD BUT LIGHT SNOWFALL ACROSS THE FORECAST AREA. KEY TO THE
SNOW PRODUCTION IS A MOIST DENDRITIC GROWTH LAYER AT 700 TO 600MB
OR THE MTN TOP LAYER. DEVELOPING MID LEVEL CYCLONIC FLOW AND A
SHOT OF COLD ADVECTION TODAY WILL ALSO KEEP SNOW PRODUCTION
WIDESPREAD.
THE MAIN SYNOPTIC FEATURE IS THE CLOSED LOW OVER EASTERN WYOMING
THAT IS ROTATING SPOKES OF ENERGY MAINLY ACROSS THE NORTHERN
ZONES. THIS LOW WILL SHIFT EAST THIS MORNING WITH THE LAST
TRAILING DISTURBANCE AND SHOT OF COLD AIR ROTATING OVER THE NORTHERN
COLORADO MTNS. IN ADDITION THE 500-300MB SHEAR AXIS REMAINS OVER
THE SW SAN JUAN REGION THROUGH THE MORNING HOURS. SANDWICHED
BETWEEN THESE TWO LARGER SCALE FEATURES...THE CENTRAL ZONES ARE
ACCUMULATING THE LEAST SNOW AMOUNTS. IT WILL BE DIFFICULT FOR
GRAND JUNCTION AND MONTROSE TO ACCUMULATE 3 INCHES OF SNOW...BUT
WITH SNOWFALL CONTINUING WILL KEEP THE ADVISORIES ACTIVE.
OTHERWISE THE VEERING WINDS ALOFT FROM WEST TO NORTH WILL PRODUCE
SNOWFALL MAINLY ON NORTH FACING SLOPES WHERE SKI SLOPES ARE
LOCATED. THE CENTRAL VALLEYS COULD ALSO SEE A QUICK FEW INCHES OF
SNOWFALL IN THE LATE AFTERNOON INTO THE EARLY EVENING.
TONIGHT...NORTH FLOW CONTINUES WITH WEAK TRANSIENT RIDGING
BUILDING AFTER MIDNIGHT. IN SPITE OF THIS...LIGHT OROGRAPHIC
SNOWFALL IS EXPECTED FAVORING THE NORTHERN MTNS. FRIDAY...A DRIER
AIR MASS WORKS IN FROM WEST TO EAST WITH LIGHT SNOWFALL CONTINUING
ONLY IN THE EASTERN MTNS. WARM ADVECTION ALOFT BEGINS IN THE
AFTERNOON STRONGLY CAPPING THE COLD AIR IN THE VALLEYS.
.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 346 AM MST THU DEC 27 2012
SNOW COMES TO AN END OVER THE ENTIRE FORECAST AREA FRIDAY NIGHT AS
SHRTWV RIDGE WORKS EAST. THIS WILL BRING DRY CONDITIONS THROUGH
EARLY SUNDAY...BEFORE NEXT LONG WAVE TROUGH WORKS INTO THE WESTERN
U.S. MEDIUM RANGE MODELS STILL ON DIFFERENT PATHS IN REGARDS TO
THIS SPLITTING SYSTEM WITH THE ECMWF CONTINUING TO DRIVE THE
SOUTHERN EXTENT OF THE TROUGH SOUTH INTO THE BAJA REGION BY
SUNDAY...WITH SPLITTING NORTHERN ENERGY SLOWLY DROPPING SOUTHWEST
ACROSS THE WESTERN GREAT BASIN AND EVENTUALLY PHASING WITH THE
SOUTHERN STREAM...THEN EJECTING OUT BY MIDWEEK. THIS KEEPS PRECIP
OUT OF OUR REGION UNTIL LATER MONDAY WITH MAIN IMPACT ACROSS THE
SOUTHERN ZONES.
THE GFS ON THE OTHER HAND SPLITS THE TROUGH AS WELL...BUT FOCUS IS
ON THE NORTHERN STREAM WHICH DRIVES THROUGH THE FORECAST AREA AS A
POSITIVELY TILTED TROUGH SUNDAY NIGHT AND MONDAY...WHICH WOULD
BRING A GOOD CHANCE OF SNOW TO MUCH OF THE FORECAST
AREA.
WITH THESE TWO OUT OF PHASE...DECIDED TO TAKE A CLOSER LOOK AT THE
CANADIAN AND OTHER ENSEMBLES AVAILABLE WHICH OFFERING MORE OF A
COMPROMISE BETWEEN THE TWO. SO WILL KEEP LOW POPS IN THE FORECAST
BEGINNING AS EARLY AS SUNDAY AFTERNOON AND PEAKING ON MONDAY. THE
GFS HAS MAINTAINED SOME CONSISTENCY OVER THE PAST FEW RUNS...SO
SOME INCREASE IN CONFIDENCE TOWARD THAT SOLUTION...BUT NOT ENOUGH
TO DRIVE POPS INTO THE LIKELY THRESHOLD.
BEYOND THIS EVENT...THE FORECAST REMAINS RATHER UNSETTLED WITH
ANOTHER FAST MOVING SYSTEM RUNNING THROUGH TUESDAY
AFTERNOON...FOLLOWED BY TRANSITORY RIDGING AT MIDWEEK WITH YET
ANOTHER SYSTEM POSSIBLE BY THE END OF THE WEEK.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 346 AM MST THU DEC 27 2012
PERIODS OF MODERATE SNOWFALL WILL CONTINUE NORTH OF THE I-70
CORRIDOR THROUGH 18Z THEN DIMINISH IN COVERAGE. SNOWFALL WILL
RESULT IN MOUNTAIN OBSCURATIONS AND MVFR CIGS AND VSBY FOR KVEL
KCAG KSBS. SOUTH OF I-70 SNOWFALL WILL GENERALLY BE LIGHTER AND
MORE SPORADIC. EXPECT PERIODS OF MVFR/ISOLD IFR CONDITIONS THROUGH
TODAY. THE FLOW TURNS TO COLD NW THIS AFTERNOON AND EVENING
WITH WIDESPREAD SNOWFALL ALONG NORTH AND NORTHWEST FACING SLOPES.
&&
.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...JAD
SHORT TERM...JOE
LONG TERM...JDC
AVIATION...JOE+EH
AREA FORECAST DISCUSSION...UPDATED
NWS DULUTH MN
1113 AM CST THU DEC 27 2012
.UPDATE...
GOING FORECAST WAS PRETTY GOOD WITH NAILING THE SNOW BANDS STREAMING
ONTO THE NORTH SHORE. WITH REPORT OF 4.5 INCHES OF SNOW AT WOLF
RIDGE ENVIRONMENTAL LEARNING CENTER SINCE LAST NIGHT DECIDED TO
ISSUE ADVISORY. ESPECIALY SINCE THE SNOW WILL FALL OFF AND ON
THROUGH THIS AFTERNOON AND TONIGHT. THE LATEST 15Z RAP MODEL SHOWS
A BIT OF A SLOWDOWN THIS AFTERNOON THEN MORE SNOW TONIGHT...IN THE
SAME AREAS...FROM TWO HARBORS THORUGH LITTLE MARAIS. GREATEST
AMUNTS WILL BE IN THE HIGHER TERRAIN INLAND FROM THE LAKE.
&&
.PREV DISCUSSION... /ISSUED 521 AM CST THU DEC 27 2012/
AVIATION.../12Z TAF ISSUANCE/
VFR CONDITIONS ARE MOST LIKELY ACROSS NE MINNESOTA AND NW
WISCONSIN THIS MORNING. HOWEVER...MVFR CIGS WILL BRIEFLY AFFECT
KHYR THIS MORNING...AND COULD ALSO AFFECT KDLH. EXPECT THE BKN/OVC
HIGH CLOUDS MOVING INTO THE REGION FROM THE W AND SW TO LOWER INTO
THIS AFTERNOON AND EVENING. THIS WILL BEGIN TO RESULT IN MVFR
CIGS FOR THE REGION LATE THIS AFTERNOON AND TONIGHT. THERE COULD
BE LIGHT SNOW TONIGHT THAT COULD RESULT IN REDUCED VISIBILITY. IFR
VSBYS ARE NOT OUT OF THE QUESTION WITH THE SNOW...BUT VSBY WILL
PROBABLY NOT GET MUCH LOWER THAN MVFR. THE WINDS WILL BE LIGHT AND
VARIABLE THROUGH TONIGHT.
PREV DISCUSSION... /ISSUED 403 AM CST THU DEC 27 2012/
SHORT TERM...TODAY THROUGH FRIDAY.
MAIN FOCUS IN SHORT RANGE ON PERIODIC MESO-LOW
DEVELOPMENT...PRODUCING LOCALIZED SNOWFALL...THAT WILL TRACK OVER
THE WATERS OF WRN LAKE SUPERIOR...OCCASIONALLY MAKING LANDFALL.
GENERALLY HAVE BROADBRUSH CHC/LIKELY POPS FOR AREAS ADJACENT TO
LAKE SUPERIOR THROUGH FRIDAY TO ACCOUNT FOR THESE FEATURES.
CURRENT RADAR IMAGERY AND MARINE OBSERVATIONS ARE SHOWING A WELL
DEFINED LOW CURRENTLY SITUATED BETWEEN SILVER BAY AND THE WESTERN
APOSTLE ISLANDS. THE LATEST HIGH- RES DLHWRF/HRRR/RAW ARE
INITIALIZING WELL WITH THE PLACEMENT OF THIS MESO-LOW...ALTHOUGH
THESE VERY SMALL SCALE PHENOMENON ARE EXTREMELY DIFFICULT FOR
EVEN HIGH RES MODELS TO CAPTURE. MODELS ARE SUGGESTING THE MESO-
LOW TRANSLATES EAST THROUGH THE REMAINDER OF THE NIGHT...CENTERING
OVER THE APOSTLE ISLANDS/BAYFIELD PENINSULA BY DAY BREAK. HAVE
INCREASED POPS/SNOW AMOUNTS ACROSS THIS AREA REGION WITH
HIGHER CONFIDENCE IN VERY NEAR TERM. THERE IS ALSO AGREEMENT THAT
VERY LOCALIZED SNOW ACCUMULATIONS OF UP TO 3 INCHES WILL BE FOUND
UNDER THE SNOW BANDS NEAR THE LOW TODAY. AT THIS TIME...THE
GREATEST CHANCE TO SEE A FEW INCHES OF ACCUMULATING SNOW TODAY
WILL BE FROM DEVILS ISLAND...TO SAND BAY...TO PORT WING.
HOWEVER...THIS IS HIGHLY DEPENDENT ON THE SPEED AND TRACK OF THE
MESO-LOW. THERE IS REASONABLE MODEL AGREEMENT THAT THE LOW EXITS
THE APOSTLE ISLANDS AREA BY MID-DAY...THEN ROTATES
ANTI-CYCLONICALLY BACK AROUND TO THE NORTH SHORE...MAKING LANDFALL
IN THE VIN CITY OF TWO HARBORS TO SILVER BAY. IF THIS TRACK IS
CORRECT THEN AN INCH OR TWO OF VERY LOCALIZED SNOWFALL WILL BE
POSSIBLE IN THIS REGION THIS AFTERNOON AS WELL.
ELSEWHERE...A SHORT WAVE TRANSLATING EAST OVER SOUTH DAKOTA TODAY
WILL DROP SE ACROSS IOWA TONIGHT. THIS WAVE WILL SPREAD CLOUDS
OVER THE REGION...AS WELL AS BRING A CHANCE FOR LIGHT SNOW
ACCUMULATION OVERNIGHT THROUGH FRIDAY. AMOUNTS OF GENERALLY A HALF
INCH OR LESS ARE ANTICIPATED ATTM...WITH THE EXCEPTION OF AREAS
ADJACENT TO LAKE SUPERIOR WHERE HIGHER AMOUNTS MAY BE FOUND.
LONG TERM [FRIDAY NIGHT - THURSDAY]...
A MID/UPPER LEVEL TROUGH WILL MOVE THROUGH THE NORTHLAND EARLY THIS
WEEKEND AND PROVIDE LOW CHANCES OF LIGHT SNOW FOR MUCH OF THE FA
INTO SATURDAY. THE WNW FLOW THAT WILL DEVELOP IN THE WAKE OF THE
TROUGH COULD DEVELOP SOME LAKE EFFECT SNOW SHOWERS LATE SATURDAY AND
INTO EARLY SUNDAY IN IRON COUNTY IN NW WISCONSIN. THE MODELS ARE IN
REASONABLE AGREEMENT THAT A CLIPPER LIKE SYSTEM WILL PASS NEAR OR
NORTH OF THE MINNESOTA/CANADA BORDER SUNDAY AND EARLY NEXT WORK
WEEK...WHICH WILL PROVIDE MORE LOW CHANCES OF LIGHT SNOW. AN
ASSOCIATED COLD FRONT WILL PASS THROUGH THE NORTHLAND SUNDAY NIGHT.
THE NNW TO NW WINDS IN THE WAKE OF THE COLD FRONT COULD RESULT IN
LAKE EFFECT SNOW SHOWERS NEAR THE GOGEBIC RANGE IN NW WISCONSIN
MONDAY AND MONDAY NIGHT. TEMPERATURES THROUGH THE PERIOD SHOULD BE
NEAR NORMAL.
PREV DISCUSSION... /ISSUED 1146 PM CST WED DEC 26 2012/
AVIATION.../06Z TAF ISSUANCE/
CLOUD FORECASTS WILL BE A BIT TRICKY OVER THE DURATION OF THIS TAF
PERIOD. IT LOOKS LIKE THE LOWEST CIGS WILL BE NEAR LAKE
SUPERIOR...AS BANDS OF SNOW SHOWERS MOVE OFF THE LAKE INTO COASTAL
AREAS. INLAND...VFR CONDITIONS SHOULD BE MORE COMMON...WITH CLOUD
BASES GRADUALLY LOWERING DURING THE DAY AND INTO THURSDAY EVENING.
LOW PRESSURE WILL GRADUALLY MOVE EASTWARD INTO THE
REGION...BRINGING SOME LIGHT SNOW DURING THE DAY AND EVENING.
&&
.POINT TEMPS/POPS...
DLH 22 13 24 9 / 20 50 50 20
INL 10 4 20 4 / 10 20 20 30
BRD 19 11 22 7 / 10 50 30 20
HYR 23 11 26 10 / 10 40 40 20
ASX 25 13 26 15 / 20 40 40 30
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...WINTER WEATHER ADVISORY UNTIL NOON CST FRIDAY FOR MNZ020.
WI...NONE.
LS...NONE.
&&
$$
SHORT TERM...CLC
LONG TERM....KK
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1234 PM CST THU DEC 27 2012
.AVIATION...
FOR THE 18Z TAF...-SN ASSOCIATED WITH AN UPPER LEVEL LOW CONTINUES
TO FALL ACROSS MUCH OF WESTERN AND NORTH CENTRAL NEBRASKA EARLY THIS
AFTERNOON...WITH VISIBILITIES LOWERING TO 1 1/2 UNDER THE HEAVIEST
OF BANDS. EXPECT PERIODS OF IFR AND MVFR TO CONTINUE ACROSS NORTH
CENTRAL NEBRASKA TERMINALS...SUCH AS KANW AND KONL THROUGH LATE
AFTERNOON AS THE UPPER LOW EJECTS ACROSS NORTHEASTERN NEBRASKA. FOR
SOUTHWEST AREA TERMINALS...STEADILY IMPROVING FLIGHT CONDITIONS WILL
BE EXPECTED THROUGH THE AFTERNOON...WITH THE POSSIBILITY OF VFR
RETURNING AT KIML AND KOGA BEFORE 20Z. OTHERWISE...SHORT TERM
GUIDANCE INDICATES CLEARING FROM SOUTHWEST TO NORTHEAST THROUGH THE
OVERNIGHT...GUIDANCE IS SPLIT ON WHETHER KLBF COMPLETELY CLEARS
OVERNIGHT TO VFR...WITH HALF OF THE SOLUTIONS INDICATING A RETURN TO
MVFR CEILINGS. THE GENERAL TREND OF THE FORECAST AT KLBF IS TO
GRADUALLY IMPROVE CEILINGS THROUGH THE OVERNIGHT...BUT SHORT-FUSED
UPDATES MAY BE NEEDED TO INCLUDE MVFR BACK INTO THE FORECAST. AT
KVTN...CONFIDENCE IS HIGHER IN MVFR CEILINGS HANGING ON THROUGH
SUNRISE...BUT GRADUALLY BREAKING FROM 12-18Z...WILL TREND THE
FORECAST IN THAT DIRECTION.
&&
.PREV DISCUSSION... /ISSUED 1037 AM CST THU DEC 27 2012/
UPDATE...
WIDESPREAD SNOW CONTINUES ACROSS MUCH OF THE FORECAST AREA...WITH
KLNX WSR-88D SHOWING THE HEAVIEST BAND NOW ACROSS NORTH CENTRAL
NEBRASKA. THIS BAND...ASSOCIATED WITH THE MAIN PV ANOMALY/UPPER
LOW WILL CONTINUE EAST...SPREADING THE HEAVIEST SNOW INTO
NORTHEASTERN PORTIONS OF THE CWA EARLY THIS AFTERNOON. FORECAST IS
ON TRACK...WITH ONLY MINOR REVISIONS IMPLEMENTED. PROXIMITY
SOUNDINGS ACROSS NORTH CENTRAL REVEAL A DEEP DENDRITIC LAYER CO-
LOCATED WITHIN A LAYER OF OMEGA. QPF AMOUNTS THUS FAR HAVE BEEN
LIGHT...GENERALLY 0.01 INCH OR LESS PER HR...WHICH THE SOUNDINGS
HAVE PICKED UP ON. HOWEVER DRY SNOW PRODUCTION HAS BEEN
EFFICIENT...WITH ACCUMULATIONS AMOUNTING TO OVER AN INCH OF DRY
FLUFFY SNOW AT KLBF OVER THE PAST 6 HOURS. TRENDED THE OVERALL QPF
AMOUNTS ACROSS THE CWA DOWNWARD...BUT INCREASED SNOW TO LIQUID
WATER RATIOS TO 25:1 AS OBSERVATIONS ARE SUGGESTING. THESE SMALL
REVISIONS DID LITTLE TO THE OVERALL EXPECTED STORM TOTAL SNOW
ACCUMULATIONS...WITH GENERALLY 2-4 INCHES OF FLUFFY SNOW EXPECTED
ACROSS NORTH CENTRAL NEBRASKA...1-2 INCHES ELSEWHERE.
PREV DISCUSSION... /ISSUED 354 AM CST THU DEC 27 2012/
SHORT TERM...TODAY THROUGH SATURDAY NIGHT
FORECAST CONCERNS THROUGH THIS PERIOD ARE SNOWFALL CHANCES AND
AMOUNTS FOR TODAY AND TONIGHT...THEN TEMPERATURES INTO THE
WEEKEND.
AT 08Z...WATER VAPOR IMAGERY SHOWED THE STRONG LOW PRESSURE SYSTEM
IMPACTING THE EAST COAST CENTERED OVER EASTERN VIRGINIA. RIDGING
WAS SITUATED OVER THE MISSISSIPPI RIVER VALLEY AS A FAIRLY LARGE
TROUGH COVERING THE WESTERN HALF OF THE CONUS. COMING OUT OF THE
TROUGH WAS AN UPPER LOW OVER EASTERN WYOMING...WHILE A PV ANOMALY
WAS SEEN OVER EASTERN COLORADO MOVING TOWARDS WESTERN NEBRASKA.
LOCALLY...RADAR ECHOES SPANNED ACROSS THE EASTERN PANHANDLE INTO
NORTHWEST NEBRASKA...WITH MORE CONVECTIVE LOOKING ECHOES OVER
CENTRAL NEBRASKA. NO PRECIPITATION WAS BEING REPORTED WITH THE
EASTERN ACTIVITY WHILE KAIA AND KSNY IN THE PANHANDLE HAD REPORTED
LIGHT SNOW BEING JUST OUTSIDE OF THE MAIN SNOW BAND. MODELS WOULD
INDICATE THE 700MB LOW OVER THE WESTERN PANHANDLE. THERE WAS A
GOOD MOISTURE FEED JUST TO THE EAST OF THE LOW WHICH HAD ITS
PRIMARY FOCUS INTO NORTHWEST NEBRASKA. THE RAP MODEL ALSO WAS
INDICATING SOME FRONTOGENETICAL FORCING AT 700 TO 600MB IN THIS SAME
AREA...WHICH WOULD FIT WITH WHAT IS ONGOING.
AS THE MORNING PROGRESSES...THE UPPER LOW OVER WYOMING WILL SHIFT
EAST INTO NORTH CENTRAL NEBRASKA AROUND MID-DAY THEN CONTINUE EAST
ALONG THE SOUTH DAKOTA/NEBRASKA BORDER INTO TONIGHT. ISENTROPIC
SURFACES FROM ROUGHLY 275K TO 290K ALL SHOWING DECENT LIFT AS WELL
AS MOISTURE TRANSPORT THROUGH THE MORNING /MAINLY OVER NORTHERN
NEBRASKA/...WHICH THEN SHIFTS EAST THIS AFTERNOON. HAVE ADJUSTED
PRECIPITATION CHANCES IN THIS FORECAST TO INCLUDE THE HIGHEST
CHANCES OVER THE PANHANDLE AND NORTHWEST NEBRASKA THIS
MORNING...THEN INTO NORTH CENTRAL NEBRASKA THIS AFTERNOON AS THE
WHOLE SYSTEM MOVES EAST. CONTINUED THE CHANCES OVER SOUTHWEST
NEBRASKA TODAY...BUT CONFIDENCE IS MUCH LESS IN THESE AREAS AND
DID BACK OFF ON CHANCES A BIT. REASONING FOR THIS IS THAT THIS
AREA WILL BE IN A FAVORABLE LOCATION FOR DRY AIR TO COME INTO THE
SYSTEM AROUND THE UPPER LOW...ALSO THE PV ANOMALY OVER COLORADO
HAS GOOD DARKENING IN THE WATER VAPOR IMAGERY INDICATING GOOD DRY
AIR ASSOCIATED WITH IT. AS THIS MOVES INTO SOUTHWEST NEBRASKA...IT
SHOULD LIMIT THE SNOWFALL. WILL PROBABLY SEE SOME SNOW IN THESE
AREAS THROUGH THE DAY...BUT BELIEVE IT WILL BE QUITE LIGHT AND
WILL NOT LAST LONG SO VERY LITTLE IF ANY ACCUMULATION IS EXPECTED.
IF IN FACT THIS OCCURS...THE FORECAST WILL LIKELY NEED TO BE
UPDATED TO REFLECT THE LOWER CHANCES FOR MEASURABLE SNOWFALL IN
THESE AREAS.
THE SYSTEM WILL NOT BE REAL FAST MOVING OUT OF THE LOCAL
AREA...WHICH WILL KEEP SNOW FALLING ACROSS NORTH CENTRAL NEBRASKA
TONIGHT BEFORE EXITING COMPLETELY ON FRIDAY. THERE HAS BEEN GOOD
MODEL AGREEMENT WITH KEEPING THE HIGHER SNOWFALL AMOUNTS JUST EAST
OF THE FORECAST AREA...MAINLY ALONG AND EAST OF HIGHWAY 14.
SOUNDINGS CONTINUE TO SHOW THE ENTIRE SATURATED LAYER /SURFACE
THROUGH 600MB/ IN THE DENTRITIC GROWTH ZONE...SO USED HIGH SNOW
RATIOS VARYING FROM 18:1 TO 23:1. EVEN WITH THIS...STORM TOTAL
SNOW AMOUNTS ACROSS HOLT AND BOYD COUNTIES ONLY SHOWING 2 TO 3
INCHES WITH A FEW LOCALIZED AREAS ABOVE 3 INCHES. GOING EAST OF
THE AREA AMOUNTS IN EXCESS OF 3 INCHES ARE LIKELY. WINDS SHOULD BE
FAIRLY LIGHT TODAY UNDER 15 MPH SO EVEN WITH THE HIGH SNOW
RATIOS GIVING HIGHER SNOW AMOUNTS DON/T FEEL THE IMPACTS WILL BE
HIGH SO WILL NOT PUT OUT AN ADVISORY FOR TODAY AND TONIGHT.
COLD AIR WILL REMAIN IN PLACE OVER THE FORECAST AREA TODAY...AND
WITH THE CLOUD COVER DON/T EXPECT HIGHS TO GET OUT OF THE TEENS.
TONIGHT AND FRIDAY...THE PRIMARY TROUGH WILL EXTEND FROM THE NORTHERN
PLANS THROUGH THE FOUR CORNERS. MEANWHILE...SEVERAL WEAK IMPULSES
OF SHORTWAVE ENERGY WILL QUICKLY PUSH SOUTH OUT OF CANADA INTO THE
CENTRAL PLAINS. THIS SHOULD KEEP AT LEAST SOME HIGH CLOUDS...BUT
MAY NOT BE TOO THICK. DID DROP LOWS ACROSS THE WESTERN PARTS OF
THE FORECAST AREA NEAR ZERO OR SLIGHTLY BELOW ZERO. IF CLOUDS
CLEAR...COULD CERTAINLY BE TOO WARM.
THE TROUGH DOES MOVE EAST INTO THE MISSISSIPPI RIVER VALLEY FRIDAY
NIGHT AND SATURDAY ALLOWING RIDGING TO START TO BUILD IN FOR THE
WEEKEND. THIS WILL BE THE START TO A SLOW WARMING TREND INTO NEXT
WEEK. NOT LOOKING FOR TEMPERATURES TO WARM DRAMATICALLY AS
SATURDAY HAS HIGHS NEAR THE FREEZING POINT. AREAS WITH SNOW COVER
WILL SEE A GREATER IMPACT IN TEMPERATURES SO IT IS LIKELY THAT
THERE WILL BE ADJUSTMENTS AFTER THE SNOW FIELD IS SAMPLED AFTER
TONIGHT.
LONG TERM...SUNDAY THROUGH WEDNESDAY
THIS PERIOD BEGINS WITH RIDGING ACROSS THE PLAINS...HOWEVER THERE
IS GOOD CONSENSUS FROM THE MODEL OUTPUT BRINGING THE NEXT STRONG
TROUGH INTO THE WEST COAST ON SUNDAY. ALSO...SEVERAL STRONG
SHORTWAVE TROUGHS ARE BEING SHOWN IN THE NORTHERN STREAM WHICH
COULD COME SOUTH FAR ENOUGH TO KEEP THE RIDGE FROM BUILDING TOO
FAR NORTH. THIS WILL KEEP TEMPERATURES FROM MODERATING TOO MUCH
THROUGH THE FIRST PART OF NEXT WEEK. THE FIRST OF THESE SYSTEMS
COMES THROUGH SUNDAY NIGHT...WHICH SHOULDN/T HAVE ANY OTHER IMPACT
BUT TO BRING SOME COOLER AIR SOUTH INTO NEBRASKA. FOR MONDAY AND
BEYOND...THE MODELS BEGIN TO DIVERGE WITH THE EASTERN MOVEMENT OF
THE WEST COAST TROUGH. THE ECMWF IS SLOWER...WHICH THEN ALLOWS A
STRONG NORTHERN STREAM SYSTEM TO PENETRATE INTO NEBRASKA TUESDAY
NIGHT. THE GFS IS QUICKER AND KEEPS THIS SYSTEM UP OVER MINNESOTA
AND THE GREAT LAKES. EITHER WAY...MOISTURE LOOKS TO BE HELD TO THE
THE MAIN UPPER LOW WHICH STAYS WELL SOUTH SO NO FURTHER
PRECIPITATION CHANCES ARE IN THE FORECAST BEYOND FRIDAY MORNING.
HYDROLOGY...
ICE JAMS ARE LIKELY TO CONTINUE AT VARIOUS LOCATIONS IN CENTRAL
AND WESTERN NEBRASKA. EXCEPT FOR STRETCHES ALONG THE NORTH PLATTE
RIVER...THERE ARE NO INDICATIONS OF FLOODING. BE AWARE THAT THE
FORMATION AND BREAK-UP OF ICE JAMS ARE NOTORIOUSLY DIFFICULT TO
FORECAST...SO RIVERS AND STREAMS IN THE AREA MAY RISE AND FALL
ERRATICALLY. WE DO HAVE FAIRLY HIGH CONFIDENCE THAT...WITH
TEMPERATURES MODERATING SOME...THE LEVELS ARE NOT LIKELY TO HAVE
NEW SHARP RISES ABOVE CURRENT LEVELS.
THE NORTH PLATTE RIVER AT LEWELLEN CONTINUES TO FALL
SLOWLY...POSSIBLY BECAUSE THE RIVER HAS BECOME COMPLETELY FROZEN
AND THE ICE IS NO LONGER BEING CARRIED TOWARD THE INLET OF LAKE
MCCONAUGHY. AT THE NORTH PLATTE GAGE...THE LEVEL CONTINUES ABOVE
FLOOD STAGE AND IS LIKELY TO CONTINUE FOR AT LEAST THIS WEEKEND.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM/EXTENDED...BROOKS
AVIATION/UPDATE...JACOBS
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1207 PM CST THU DEC 27 2012
.AVIATION...
18Z TAFS FOR KOFK...KOMA AND KLNK.
MID LEVEL SPEED MAX EXTENDING INTO NORTHWEST MISSOURI
THIS MORNING HAS HELPED TO ENHANCE SNOWFALL OVER NORTHEAST
NEBRASKA AND WEST CENTRAL IOWA. AS MAX SHIFTS EAST EXPECT SNOWFALL
RATES TO DIMINISH THIS AFTERNOON. UPPER LOW TRACKS SLOWLY EAST
ACROSS THE AREA THROUGH THE PERIOD WITH MVFR CIGS AND/OR VSBY
EXPECTED AT KOMA AND KLNK THROUGH 00Z THEN IFR CIGS AND MVFR VSBY
DEVELOPING THROUGH 06Z. SOME POTENTIAL FOR FZDZ AT KLNK YET. KOFK
LIKELY TO KEEP IFR OR LIFR CONDITIONS THROUGH MUCH OF THE PERIOD
BUT VSBY IMPROVING AS BETTER FORCING MOVES EAST AND SNOWFALL
BECOMES LIGHTER.
&&
.PREV DISCUSSION... /ISSUED 302 AM CST THU DEC 27 2012/
DISCUSSION...
.SNOW AMOUNTS AND CHANCES FOR FREEZING DRIZZLE THE MAIN
CONCERNS...
FOR THIS FORECAST THE MAIN FEATURE OF INTEREST WILL BE THE POTENT
SHORTWAVE THAT IS CURRENTLY SPINNING ALONG THE WYOMING-COLORADO
BORDER PER WATER VAPOR LOOP AND THE PRECIPITATION IT WILL PRODUCE
TODAY AND FRIDAY. THE MORE THIS SYSTEM DEVELOPS THE MORE
IMPRESSIVE IT APPEARS TO BE...ESPECIALLY FOR NORTHEAST NEBRASKA.
500 MB HEIGHT FALLS ON THE 00Z RAOBS WERE 100-120 METERS IN THE
BASE OF THE TROF...WITH DENVER SHOWING A 130 METER FALL AT 300 MB.
150 KNOT JET STREAK WAS NOTED AT 25O MB OVER ARIZONA. REGIONAL
RADAR MOSAIC SHOWS SNOW RAPIDLY DEVELOPING/EXPANDING FROM WESTERN
KANSAS INTO WESTERN AND CENTRAL NEBRASKA IN RESPONSE TO THE
SYSTEMS VERTICAL MOTION AND MOISTURE AROUND 850 MB AS SEEN ON
DODGE CITY AND NORTH PLATTE SOUNDINGS. 08Z SURFACE ANALYSIS SHOWED
EARLY STAGES OF INVERTED TROF TAKING SHAPE WITH 1003MB PRESSURES
OBSERVED IN SOUTHEAST COLORADO.
THE DODGE CITY AND NORTH PLATTE SOUNDINGS DID HAVE A FEW DRY
LAYERS AS WELL...AND THESE DRY LAYERS DO COMPLICATE THE
PRECIPITATION FORECAST. GENERALLY THE NAM/GFS/RAP ARE IN DECENT
AGREEMENT ON THE PRECIPITATION FORECAST AND THE MOIST AND DRY
LAYERS. HOWEVER THERE IS CONCERN FOR A LIGHT FREEZING DRIZZLE
SCENARIO MAINLY IN THE SOUTHERN HALF OF THE FORECAST AREA DUE TO A
LOW LEVEL SATURATED LAYER THAT IS WARMER THAN -10C AND THEREFORE
WOULD PRIMARILY CONTAIN SUPERCOOLED DRIZZLE AS OPPOSED TO
SNOWFLAKES. THE MODELS SHOW LITTLE OR NO QPF OVER SOUTHEAST
NEBRASKA THROUGH 12Z FRIDAY...HOWEVER THE MODELS OFTEN POORLY HANDLE
THESE VERY LIGHT ICING EVENTS BECAUSE THE QPF IS QUITE LIGHT BUT
ALSO BECAUSE THE LAYERS ARE SHALLOW. THE FORECAST SOUNDINGS FROM
THE NAM AND ESPECIALLY THE RAP SUPPORT AT LEAST SOME LIGHT
FREEZING DRIZZLE MAINLY ALONG AND SOUTH OF INTERSTATE 80 AT
VARIOUS TIMES FROM LATE THIS AFTERNOON INTO TONIGHT...THEREFORE
WE HAVE ADDED PATCHY FREEZING DRIZZLE...OR AREAS OF FREEZING
DRIZZLE...TO THE SNOW CHANCES IN THOSE LOCATIONS. CONFIDENCE IN
THIS LIGHT ICING SCENARIO IS NOT HIGH ENOUGH TO ISSUE A WINTER
WEATHER ADVISORY FOR THE ABOVE MENTIONED AREAS. HOWEVER IF NEW
OBSERVATIONS AND MODEL RUNS SUGGEST A HIGHER LIKELIHOOD OF
FREEZING DRIZZLE AN ADVISORY MAY BE CONSIDERED LATER TODAY.
OTHERWISE THE TRACK OF THE LOW FAVORS THE HEAVIER SNOWS TO FALL IN
NORTHEAST NEBRASKA WHERE THE GOING WINTER WEATHER ADVISORY IS AT.
WE DID ADD ONE MORE TIER OF COUNTIES TO THE ADVISORY INCLUDING
ALBION AND NORFOLK. THIS SYSTEM IS UNIQUE IN THAT IT HAS A VERY
DEEP SATURATED LAYER THAT IS IN THE DENDRITIC GROWTH ZONE...AROUND
250 MB OR ABOUT 10000 FEET DEEP...YIELDING SNOW-LIQUID RATIOS AS
HIGH AS 20-1. BECAUSE OF THIS WE ALSO INCREASED SNOW AMOUNTS IN
NORTHEAST NEBRASKA ABOUT 1 MORE INCH. FORTUNATELY THERE WILL NOT
BE A LOT OF WIND WITH THIS SYSTEM SO LITTLE BLOWING AND DRIFTING
IS EXPECTED. SOME LOCATIONS IN THE ADVISORY AREA SHOULD SEE 4-5
INCHES OF DRY/FLUFFY SNOW STARTING TODAY AND ENDING FRIDAY
MORNING.
CONFIDENCE IN THE EXACT SNOW AMOUNTS IS MUCH LOWER TO THE SOUTH
OF THE ADVISORY AREA...MAINLY FROM THE LINCOLN TO OMAHA METRO
AREAS. HOWEVER...THERE IS LITTLE SUPPORT FOR MORE THAN 2 INCHES
GIVEN THE DRY LAYERS THAT WILL NEED TO BE SATURATED AND THE
WEAKER FORCING JUST SOUTH OF THE 700 MB LOW TRACK. CURRENTLY WE
ARE KEEPING THE 1-2 INCH AMOUNTS FOR LINCOLN-OMAHA AND THIS LOOKS
REASONABLE BY NOON FRIDAY WHEN ANY LIGHT SNOW ON THE BACK SIDE OF
THE LOW FINALLY ENDS. STARTED THE CHANCES FOR SNOW A BIT LATER
EAST OF A LINE FROM LINCOLN TO FREMONT...MAINLY CLOSER TO 18Z
TODAY...PRIMARILY DUE TO THE TIME IT WILL TAKE TO SATURATE THE
DRY LOW LEVELS IN THAT AREA.
TEMPERATURE AND WIND FORECASTS WERE ONLY SLIGHTLY ADJUSTED AS THE
PATTERN REMAINS FAIRLY COLD BUT DRY AFTER FRIDAY.
NIETFELD
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...WINTER WEATHER ADVISORY UNTIL 6 AM CST FRIDAY FOR NEZ011-012-
015>018-030>034.
IA...WINTER WEATHER ADVISORY UNTIL 6 AM CST FRIDAY FOR IAZ043-055.
&&
$$
FOBERT
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1155 AM CST THU DEC 27 2012
.AVIATION...18Z KGRI TAF. MAIN ISSUES WILL BE WITH VISIBILITY
RESTRICTIONS WITH SNOW...AND STRATUS. VISIBILITY SHOULD IMPROVE
WITH TIME AS SNOW EVENTUALLY TAPERS AND MOVES OUT THIS
EVENING...BUT STRATUS WILL PROBABLY LOWER AS THE NIGHT WEARS ON
INTO THE EARLY MORNING ON FRIDAY...BEFORE RAISING AGAIN LATE
FRIDAY MORNING. WIND COULD GET A BIT MORE OF A GUST BY LATE
MORNING FRIDAY.
&&
PREV DISCUSSION... /ISSUED 243 AM CST THU DEC 27 2012/
SHORT TERM...THE MAIN ISSUE TO DEAL WITH IS TODAY/S LIGHT SNOW
EVENT.
WATER VAPOR AND INFRARED SATELLITE IMAGERY SUGGEST THE UPPER LEVEL
CIRCULATION SET TO IMPACT OUR AREA IS CENTERED IN THE TRI-STATE
CONFLUENCE OF WY/CO/NE. SPOKE OF ENERGY ALONG WITH WARM ADVECTION
PUSHING THROUGH THE FORECAST AT THIS TIME. RETURNS FROM NEARBY
RADARS SUGGEST PRECIPITATION IS DEVELOPING ALOFT IN THIS WARM
ADVECTION. NOTHING HAS REPORTEDLY MADE IT TO THE GROUND WITH DRY
AIR IN LOWER LEVELS OF THE ATMOSPHERE. THAT ALL SHOULD CHANGE
EARLY THIS MORNING...SAY AROUND DAWN...WITH LIGHT SNOWFALL STARTING
TO REACH THE SURFACE. SHORT TERM MODEL DATA /HRRR AND WRF/ POINT
TOWARD A BAND OF SNOW DEVELOPING IN THE VICINITY OF HIGHWAY 281
NAM QUICKLY LIFTING NORTH/NORTHEAST. THESE FINER DETAILS FIT WITH
THE NAM/GFS/SREF OUTPUT...WHICH EVENTUALLY PUT THE GREATEST
PRECIPITATION IN NORTHEAST NEBRASKA OF ABOUT 0.30". MEANWHILE...
THE NORTH/EAST FORECAST AREA MAY PICK UP A TENTH OR TWO OF LIQUID
EQUIVALENT MOISTURE...EQUATING INTO 1 TO 2 INCHES...MAYBE LOCALLY
3 INCHES OF SNOW. THE AREA AT MOST RISK FOR 3 INCHES...AND IT MAY
NOT BE THAT MUCH RISK...WOULD BE NORTHERN NANCE COUNTY...OR NORTHEAST
GREELEY COUNTY. THE VAST MAJORITY OF OUR NEBRASKA FORECAST IS IN
THE 1 TO 2 INCH RANGE...WITH LESS THAN 1 INCH IN NORTHERN KANSAS.
AT THIS TIME...WITH LIMITED WIND INFLUENCES...AND ONLY A SMALL PART
OF THE FORECAST AREA IN LINE FOR MARGINAL ADVISORY LEVEL SNOW
AMOUNTS...WILL NOT ISSUE ANY HEADLINES. IN FACT...IF YOU BUY INTO
THE 05Z HRRR OUTPUT...ONLY THE FAR NORTHEAST FORECAST AREA WOULD
CATCH 1 TO 2 INCHES OF SNOW...AND THE REST OF THE AREA AN INCH OR
LESS. AT THIS POINT...THERE SEEMS TO BE ENOUGH REASON NOT TO ISSUE
ANY ADVISORIES FOR THIS EVENT.
SHOULD MENTION...NAM SOUNDINGS IN THE SOUTHEAST PART OF THE FORECAST
AREA...ALONG WITH FUZZY NATURE OF PRECIPITATION OUTLOOK...SUGGEST A
BIT OF FREEZING DRIZZLE COULD DEVELOP DURING THE EVENING HOURS. LIFT
IS THE QUESTION...MEANING IS THERE ENOUGH? THINK THERE COULD BE A
COUPLE OF HOURS OF FREEZING DRIZZLE TYPE PRECIPITATION IN THIS AREA
AND HAVE ADDED THAT TO THE FORECAST GRIDS. NOT A HUGE DEAL...AND MAY
NOT MATERIALIZE...BUT WOULDN/T BE SHOCKED IF IT DID PAN OUT.
ON FRIDAY...THE MEANDERING NATURE OF THE UPPER LEVEL LOW TO THE
SOUTHEAST WILL KEEP CLOUDS AROUND FOR A GOOD PART OF THE DAY. FAR
EASTERN FORECAST AREA MAY EVEN SEE A LINGERING FLURRY EARLY IN THE
MORNING. ASIDE FROM THAT...NORTHWEST WINDS WILL DEVELOP...AND MAY
EVEN TURN SNEAKY BREEZY IF CLEARING DEVELOPS MORE RAPIDLY. FRIDAY
IS STILL A PART OF THE CURRENT COLD SPELL WITH HIGHS STRUGGLING FOR
ABOUT 20 MOST AREAS. THAT ALL STARTS TO CHANGE FRIDAY NIGHT...AS
DOWN-SLOPING WESTERLY WINDS SET UP AND LASTS INTO THE DAY SATURDAY.
THIS WILL RESULT IN SATURDAY BEING MUCH WARMER...RELATIVE TO RECENT
DAYS...WITH HIGHS IN THE UPPER 20S AND LOWER 30S AND PLENTY OF
SUNSHINE. THAT WON/T NECESSARILY MELT A WHOLE LOT...AND ITS STILL
BELOW NORMAL SOME 5 TO 7 DEGREES...BUT ITS AT LEAST A START.
LONG TERM...STARTING SUNDAY MORNING...SUNDAY IS SHAPING UP TO BE
THE WARMEST DAY IN JUST OVER A WEEK AS THE COMBINATION OF WARMER AIR
SURGING NORTHWARD AHEAD OF AN APPROACHING LOW LEVEL TROUGH/FRONT AND
MOSTLY SUNNY SKIES UNDER THE INFLUENCE OF A BUILDING UPPER LEVEL
RIDGE...WILL RESULT IN A RETURN TO NEAR SEASONAL TEMPERATURES FOR
THE END OF DECEMBER. AS A RESULT...EXPECT TO SEE AFTERNOON
TEMPERATURES ACROSS SOUTH CENTRAL NEBRASKA APPROACH THE FREEZING
MARK...WITH UPPER 30S TO NEAR 40 DEGREES CURRENTLY FORECAST FOR
PORTIONS OF NORTH CENTRAL KANSAS. WHILE THIS LIKELY WILL NOT BE WARM
ENOUGH TO RESULT IN ANY SIGNIFICANT MELTING OF SNOW/ICE ON THE
GROUND...IT WILL LIKELY BE THE FIRST DAY SINCE DECEMBER 22ND THAT
TEMPERATURES WILL CLIMB ABOVE THE FREEZING MARK ACROSS THE MAJORITY
OF THE FORECAST AREA. THIS BRIEF WARM UP...HOWEVER...IS EXPECTED TO
BE FAIRLY SHORT LIVED...AS GLOBAL MODELS ARE INDICATING COOLER AIR
BEHIND THE APPROACHING TROUGH/FRONT...WHICH WILL BEGIN TO FILTER IN
ACROSS THE LOCAL AREA TO START THE NEW WORK WEEK. AS A
RESULT...EXPECT A RETURN TO SUBFREEZING AFTERNOON TEMPERATURES
MONDAY AFTERNOON WITH LITTLE EVIDENCE FOR ENOUGH LOW LEVEL MOISTURE
OR FORCING TO JUSTIFY ANYTHING OTHER THAN AN INCREASE IN CLOUDS
ACROSS THE LOCAL AREA MONDAY.
THEREAFTER...THE GLOBAL MODELS BEGIN TO DIVERGE SOME WITH THEIR
HANDLING OF AN UPPER LEVEL LOW ACROSS THE DESERT SOUTHWEST...WITH
THE GFS MAINTAINING A MUCH MORE PROGRESSIVE FLOW PATTERN THAN THE
EC...WHICH HAS BEEN TRYING TO CUT OFF THE UPPER LEVEL LOW ACROSS
NORTHERN MEXICO. HOWEVER...IN BOTH SCENARIOS...THE NORTHERN JET IS
FORECAST TO STEER AN UPPER LEVEL DISTURBANCE ACROSS NEBRASKA TUESDAY
NIGHT/WEDNESDAY...WHICH ONCE AGAIN IS EXPECTED TO HAVE A LACK IN
APPRECIABLE LOW LEVEL MOISTURE...WITH LITTLE MORE THAN A FEW HIGH
CLOUDS AND A CONTINUATION OF SUB FREEZING TEMPERATURES EXPECTED TO
PERSIST AS A RESULT. JUST BEYOND THE CURRENT SCOPE OF THE
FORECAST...THERE ARE SOME INDICATIONS THAT ANOTHER UPPER LEVEL RIDGE
OF HIGH PRESSURE WILL BUILD ACROSS THE CENTRAL PLAINS IN CONCERT
WITH A MORE SIGNIFICANT DOWN-SLOPING LOW LEVEL FLOW...WHICH MAY
RESULT IN TEMPERATURES WARMING ABOVE CLIMO TOWARDS THE END OF NEXT
WEEK.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
AVIATION...HEINLEIN
SHORT TERM...NOAA/NWS/MORITZ
LONG TERM...SAR
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1037 AM CST THU DEC 27 2012
.UPDATE...
WIDESPREAD SNOW CONTINUES ACROSS MUCH OF THE FORECAST AREA...WITH
KLNX WSR-88D SHOWING THE HEAVIEST BAND NOW ACROSS NORTH CENTRAL
NEBRASKA. THIS BAND...ASSOCIATED WITH THE MAIN PV ANOMALY/UPPER
LOW WILL CONTINUE EAST...SPREADING THE HEAVIEST SNOW INTO
NORTHEASTERN PORTIONS OF THE CWA EARLY THIS AFTERNOON. FORECAST IS
ON TRACK...WITH ONLY MINOR REVISIONS IMPLEMENTED. PROXIMITY
SOUNDINGS ACROSS NORTH CENTRAL REVEAL A DEEP DENDRITIC LAYER CO-
LOCATED WITHIN A LAYER OF OMEGA. QPF AMOUNTS THUS FAR HAVE BEEN
LIGHT...GENERALLY 0.01 INCH OR LESS PER HR...WHICH THE SOUNDINGS
HAVE PICKED UP ON. HOWEVER DRY SNOW PRODUCTION HAS BEEN
EFFICIENT...WITH ACCUMULATIONS AMOUNTING TO OVER AN INCH OF DRY
FLUFFY SNOW AT KLBF OVER THE PAST 6 HOURS. TRENDED THE OVERALL QPF
AMOUNTS ACROSS THE CWA DOWNWARD...BUT INCREASED SNOW TO LIQUID
WATER RATIOS TO 25:1 AS OBSERVATIONS ARE SUGGESTING. THESE SMALL
REVISIONS DID LITTLE TO THE OVERALL EXPECTED STORM TOTAL SNOW
ACCUMULATIONS...WITH GENERALLY 2-4 INCHES OF FLUFFY SNOW EXPECTED
ACROSS NORTH CENTRAL NEBRASKA...1-2 INCHES ELSEWHERE.
&&
.PREV DISCUSSION... /ISSUED 542 AM CST THU DEC 27 2012/
AVIATION...
LIGHT SNOW IS EXPECTED TO CONTINUE NORTH AND WEST OF AN
ANW-TIF-MHN-OGA LINE THROUGH 21Z WITH THE HEAVIEST FROM 14-18Z.
CEILINGS BELOW 3000 FEET AGL ARE LIKELY WITH A FAIRLY STRONG
PROBABILITY OF 1000-2000 FEET AGL. IN ADDITION...WIDESPREAD
VISIBILITY BELOW 3SM CAN BE EXPECTED IN THE HEAVIER SNOW WITH LESS
THAN 1SM POSSIBLE. LOW CEILING AND VISIBILITY MAY CONTINUE UNTIL AT
LEAST THIS EVENING 03Z...ESPECIALLY IN NORTH CENTRAL NEBRASKA.
PREV DISCUSSION... /ISSUED 354 AM CST THU DEC 27 2012/
SHORT TERM...TODAY THROUGH SATURDAY NIGHT
FORECAST CONCERNS THROUGH THIS PERIOD ARE SNOWFALL CHANCES AND
AMOUNTS FOR TODAY AND TONIGHT...THEN TEMPERATURES INTO THE
WEEKEND.
AT 08Z...WATER VAPOR IMAGERY SHOWED THE STRONG LOW PRESSURE SYSTEM
IMPACTING THE EAST COAST CENTERED OVER EASTERN VIRGINIA. RIDGING
WAS SITUATED OVER THE MISSISSIPPI RIVER VALLEY AS A FAIRLY LARGE
TROUGH COVERING THE WESTERN HALF OF THE CONUS. COMING OUT OF THE
TROUGH WAS AN UPPER LOW OVER EASTERN WYOMING...WHILE A PV ANOMALY
WAS SEEN OVER EASTERN COLORADO MOVING TOWARDS WESTERN NEBRASKA.
LOCALLY...RADAR ECHOES SPANNED ACROSS THE EASTERN PANHANDLE INTO
NORTHWEST NEBRASKA...WITH MORE CONVECTIVE LOOKING ECHOES OVER
CENTRAL NEBRASKA. NO PRECIPITATION WAS BEING REPORTED WITH THE
EASTERN ACTIVITY WHILE KAIA AND KSNY IN THE PANHANDLE HAD REPORTED
LIGHT SNOW BEING JUST OUTSIDE OF THE MAIN SNOW BAND. MODELS WOULD
INDICATE THE 700MB LOW OVER THE WESTERN PANHANDLE. THERE WAS A
GOOD MOISTURE FEED JUST TO THE EAST OF THE LOW WHICH HAD ITS
PRIMARY FOCUS INTO NORTHWEST NEBRASKA. THE RAP MODEL ALSO WAS
INDICATING SOME FRONTOGENETICAL FORCING AT 700 TO 600MB IN THIS SAME
AREA...WHICH WOULD FIT WITH WHAT IS ONGOING.
AS THE MORNING PROGRESSES...THE UPPER LOW OVER WYOMING WILL SHIFT
EAST INTO NORTH CENTRAL NEBRASKA AROUND MID-DAY THEN CONTINUE EAST
ALONG THE SOUTH DAKOTA/NEBRASKA BORDER INTO TONIGHT. ISENTROPIC
SURFACES FROM ROUGHLY 275K TO 290K ALL SHOWING DECENT LIFT AS WELL
AS MOISTURE TRANSPORT THROUGH THE MORNING /MAINLY OVER NORTHERN
NEBRASKA/...WHICH THEN SHIFTS EAST THIS AFTERNOON. HAVE ADJUSTED
PRECIPITATION CHANCES IN THIS FORECAST TO INCLUDE THE HIGHEST
CHANCES OVER THE PANHANDLE AND NORTHWEST NEBRASKA THIS
MORNING...THEN INTO NORTH CENTRAL NEBRASKA THIS AFTERNOON AS THE
WHOLE SYSTEM MOVES EAST. CONTINUED THE CHANCES OVER SOUTHWEST
NEBRASKA TODAY...BUT CONFIDENCE IS MUCH LESS IN THESE AREAS AND
DID BACK OFF ON CHANCES A BIT. REASONING FOR THIS IS THAT THIS
AREA WILL BE IN A FAVORABLE LOCATION FOR DRY AIR TO COME INTO THE
SYSTEM AROUND THE UPPER LOW...ALSO THE PV ANOMALY OVER COLORADO
HAS GOOD DARKENING IN THE WATER VAPOR IMAGERY INDICATING GOOD DRY
AIR ASSOCIATED WITH IT. AS THIS MOVES INTO SOUTHWEST NEBRASKA...IT
SHOULD LIMIT THE SNOWFALL. WILL PROBABLY SEE SOME SNOW IN THESE
AREAS THROUGH THE DAY...BUT BELIEVE IT WILL BE QUITE LIGHT AND
WILL NOT LAST LONG SO VERY LITTLE IF ANY ACCUMULATION IS EXPECTED.
IF IN FACT THIS OCCURS...THE FORECAST WILL LIKELY NEED TO BE
UPDATED TO REFLECT THE LOWER CHANCES FOR MEASURABLE SNOWFALL IN
THESE AREAS.
THE SYSTEM WILL NOT BE REAL FAST MOVING OUT OF THE LOCAL
AREA...WHICH WILL KEEP SNOW FALLING ACROSS NORTH CENTRAL NEBRASKA
TONIGHT BEFORE EXITING COMPLETELY ON FRIDAY. THERE HAS BEEN GOOD
MODEL AGREEMENT WITH KEEPING THE HIGHER SNOWFALL AMOUNTS JUST EAST
OF THE FORECAST AREA...MAINLY ALONG AND EAST OF HIGHWAY 14.
SOUNDINGS CONTINUE TO SHOW THE ENTIRE SATURATED LAYER /SURFACE
THROUGH 600MB/ IN THE DENTRITIC GROWTH ZONE...SO USED HIGH SNOW
RATIOS VARYING FROM 18:1 TO 23:1. EVEN WITH THIS...STORM TOTAL
SNOW AMOUNTS ACROSS HOLT AND BOYD COUNTIES ONLY SHOWING 2 TO 3
INCHES WITH A FEW LOCALIZED AREAS ABOVE 3 INCHES. GOING EAST OF
THE AREA AMOUNTS IN EXCESS OF 3 INCHES ARE LIKELY. WINDS SHOULD BE
FAIRLY LIGHT TODAY UNDER 15 MPH SO EVEN WITH THE HIGH SNOW
RATIOS GIVING HIGHER SNOW AMOUNTS DON/T FEEL THE IMPACTS WILL BE
HIGH SO WILL NOT PUT OUT AN ADVISORY FOR TODAY AND TONIGHT.
COLD AIR WILL REMAIN IN PLACE OVER THE FORECAST AREA TODAY...AND
WITH THE CLOUD COVER DON/T EXPECT HIGHS TO GET OUT OF THE TEENS.
TONIGHT AND FRIDAY...THE PRIMARY TROUGH WILL EXTEND FROM THE NORTHERN
PLANS THROUGH THE FOUR CORNERS. MEANWHILE...SEVERAL WEAK IMPULSES
OF SHORTWAVE ENERGY WILL QUICKLY PUSH SOUTH OUT OF CANADA INTO THE
CENTRAL PLAINS. THIS SHOULD KEEP AT LEAST SOME HIGH CLOUDS...BUT
MAY NOT BE TOO THICK. DID DROP LOWS ACROSS THE WESTERN PARTS OF
THE FORECAST AREA NEAR ZERO OR SLIGHTLY BELOW ZERO. IF CLOUDS
CLEAR...COULD CERTAINLY BE TOO WARM.
THE TROUGH DOES MOVE EAST INTO THE MISSISSIPPI RIVER VALLEY FRIDAY
NIGHT AND SATURDAY ALLOWING RIDGING TO START TO BUILD IN FOR THE
WEEKEND. THIS WILL BE THE START TO A SLOW WARMING TREND INTO NEXT
WEEK. NOT LOOKING FOR TEMPERATURES TO WARM DRAMATICALLY AS
SATURDAY HAS HIGHS NEAR THE FREEZING POINT. AREAS WITH SNOW COVER
WILL SEE A GREATER IMPACT IN TEMPERATURES SO IT IS LIKELY THAT
THERE WILL BE ADJUSTMENTS AFTER THE SNOW FIELD IS SAMPLED AFTER
TONIGHT.
LONG TERM...SUNDAY THROUGH WEDNESDAY
THIS PERIOD BEGINS WITH RIDGING ACROSS THE PLAINS...HOWEVER THERE
IS GOOD CONSENSUS FROM THE MODEL OUTPUT BRINGING THE NEXT STRONG
TROUGH INTO THE WEST COAST ON SUNDAY. ALSO...SEVERAL STRONG
SHORTWAVE TROUGHS ARE BEING SHOWN IN THE NORTHERN STREAM WHICH
COULD COME SOUTH FAR ENOUGH TO KEEP THE RIDGE FROM BUILDING TOO
FAR NORTH. THIS WILL KEEP TEMPERATURES FROM MODERATING TOO MUCH
THROUGH THE FIRST PART OF NEXT WEEK. THE FIRST OF THESE SYSTEMS
COMES THROUGH SUNDAY NIGHT...WHICH SHOULDN/T HAVE ANY OTHER IMPACT
BUT TO BRING SOME COOLER AIR SOUTH INTO NEBRASKA. FOR MONDAY AND
BEYOND...THE MODELS BEGIN TO DIVERGE WITH THE EASTERN MOVEMENT OF
THE WEST COAST TROUGH. THE ECMWF IS SLOWER...WHICH THEN ALLOWS A
STRONG NORTHERN STREAM SYSTEM TO PENETRATE INTO NEBRASKA TUESDAY
NIGHT. THE GFS IS QUICKER AND KEEPS THIS SYSTEM UP OVER MINNESOTA
AND THE GREAT LAKES. EITHER WAY...MOISTURE LOOKS TO BE HELD TO THE
THE MAIN UPPER LOW WHICH STAYS WELL SOUTH SO NO FURTHER
PRECIPITATION CHANCES ARE IN THE FORECAST BEYOND FRIDAY MORNING.
HYDROLOGY...
ICE JAMS ARE LIKELY TO CONTINUE AT VARIOUS LOCATIONS IN CENTRAL
AND WESTERN NEBRASKA. EXCEPT FOR STRETCHES ALONG THE NORTH PLATTE
RIVER...THERE ARE NO INDICATIONS OF FLOODING. BE AWARE THAT THE
FORMATION AND BREAK-UP OF ICE JAMS ARE NOTORIOUSLY DIFFICULT TO
FORECAST...SO RIVERS AND STREAMS IN THE AREA MAY RISE AND FALL
ERRATICALLY. WE DO HAVE FAIRLY HIGH CONFIDENCE THAT...WITH
TEMPERATURES MODERATING SOME...THE LEVELS ARE NOT LIKELY TO HAVE
NEW SHARP RISES ABOVE CURRENT LEVELS.
THE NORTH PLATTE RIVER AT LEWELLEN CONTINUES TO FALL
SLOWLY...POSSIBLY BECAUSE THE RIVER HAS BECOME COMPLETELY FROZEN
AND THE ICE IS NO LONGER BEING CARRIED TOWARD THE INLET OF LAKE
MCCONAUGHY. AT THE NORTH PLATTE GAGE...THE LEVEL CONTINUES ABOVE
FLOOD STAGE AND IS LIKELY TO CONTINUE FOR AT LEAST THIS WEEKEND.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM/EXTENDED...BROOKS
UPDATE/AVIATION...JACOBS
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
509 PM EST THU DEC 27 2012
.SYNOPSIS...
A WEAK AREA OF HIGH PRESSURE WILL SLOWLY PUSH TO THE EAST
OVERNIGHT. AN UPPER LEVEL DISTURBANCE AND ITS ASSOCIATED SURFACE
BOUNDARIES WILL BRING A MIX OF PRECIPITATION TO THE REGION FRIDAY
NIGHT AND EARLY SATURDAY.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
SATELLITE SHOWING THAT INCREASING CLOUD BREAKS NOW BEGINNING TO
FILL BACK IN. CURRENT THINKING IS THAT THE RETURN FLOW BEHIND THE
DEPARTING SURFACE HIGH WILL ALLOW ADDITIONAL MOISTURE AHEAD OF THE
NEXT SYSTEM APPROACHING FROM THE SOUTHERN PLAINS AND THAT BREAKS
WILL CONTINUE TO FILL IN. CURRENTLY HAVE A TIGHT GRADIENT OF
OVERNIGHT LOWS FROM THE MID 20S SOUTH TO THE UPPER TEENS NEAR
WAPAKONETA. WILL HAVE TO MONITOR THE CLOUDS IN THE NORTH...AS IF
BREAKS WORK IN...TEMPS WILL PLUMMET WITH CLOUD COVER AND VERY
LIGHT WINDS. GENERALLY WENT ON THE LOWER END OF MOS GUIDANCE
SOLUTIONS.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
WHILE A FAIR AMOUNT OF MID AND HIGH CLOUDS THROUGH THE DAY ON
FRIDAY...WARMER AIR BEGINST TO WORK ESPECIALLY INTO THE SOUTHERN
FCST AREA...WHICH WILL ALLOW LOW 40S IN THE SOUTH...BUT HIGHS
STILL BELOW OR JUST AT FREEZING IN THE NORTH.
THE NEXT WEATHER MAKER WILL COME ON FRIDAY NIGHT...AS A DEVELOPING
UPR LEVEL TROUGH WILL ADVANCE FROM THE MS VALLEY AND PIVOT ENE
THROUGH THE UPPR OH VALLEY. GFS IS FURTHER NORTH AND A LITTLE
SLOWER AND DEEPER WITH THE LOW THAN THE 12Z ECMWF...WTH THE NAM
THE OUTLIER IN POSITIONING AND TIMING. SOLUTION IS A BLEND BETWEEN
THE GFS/ECMWF...SLIGHTLY FAVORING THE 12Z ECMWF. GFS QPF HAS SOME HEAVIER
PRECIP AMOUNTS TO THE NW OF THE SFC LOW...WHEREAS THE ECMWF HAS
THE HEAVIEST PRECIPITATION IN THE WARMER AIR NEAR AND SOUTH OF THE
LOW. HAVE ALSO SIDED CLOSER TO ECMWF FOR QPF. THE TRICKY PART IS
THE TIMING OF THE PRECIP WITH SOME WAA EXPECTED NEAR THE OHIO
RIVER AND A WARM NOSE PUSHING INTO THE PORTSMOUTH AREA...WHERE THE
HEAVIEST QPF IS EXPECTED TO BE. THE HEAVIEST PRECIP APPEARS TO BE
JUST ON EITHER SIDE OF THE 06Z TIMEFRAME...SO IF LOW LEVELS AND
SFC ARE COLD ENOUGH...ADVISORY CRITERIA FOR SNOW MAY BE MET
ESPECIALLY NEAR THE I-71 CORRIDOR AND POSSIBLY TO THE SOUTHEAST.
NEED MORE CONFIDENCE FOR SUCH ISSUANCE...SO NO PRODUCT ISSUANCES
AT THIS TIME.
SYSTEM FAIRLY QUICK TO PUSH EAST OF FCST AREA...WITH SFC BOUNDARY
AND COLDER AIR TO WORK IN DURING THE DAY ON SATURDAY WITH
LINGERING SNOW SHOWERS.
SKIES WILL BE SLOW TO CLEAR FOR SAT NIGHT...SO WHILE CAA WORKING
IN...WON`T BE COMBINED WITH RADIATIONAL COOLING OVER ANY NEW SNOW
COVER. GENERALLY NER 20 TO LOW 20S FOR LOWS.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
SURFACE HIGH PRESSURE WILL BEGIN TO BUILD INTO THE OHIO VALLEY
SUNDAY MORNING BEHIND A DEPARTING UPPER LEVEL TROUGH. CLOUDS WILL
SLOWLY DIMINISH FROM WEST TO EAST THROUGH THE DAY GIVING WAY FOR A
BRIEF PERIOD OF SOME SUNSHINE. WITH A COLDER AIRMASS OVER THE
REGION...TEMPERATURES WILL REMAIN BELOW NORMAL WITH HIGHS IN THE
UPPER 20S TO LOWER 30S AND LOWS SUNDAY NIGHT IN THE TEENS TO LOWER
20S. RETURN FLOW AROUND THE BACKSIDE OF THE HIGH WILL ALLOW FOR A
RETURN TO MORE SEASONAL TEMPERATURES BY MONDAY.
LAST FEW MODEL RUNS HAVE SLIGHTLY SPED UP THE APPROACH OF A COLD
FRONT FOR MONDAY EVENING/OVERNIGHT. SOUTHWESTERLY FLOW WILL DRAW
INCREASING MOISTURE IN FROM THE SOUTH DURING THE DAY. MODELS HAVE
BEEN TRENDING FURTHER NORTH AND EAST WITH PRECIPITATION OUT AHEAD OF
THE FRONT...SO INTRODUCED POPS FOR OUR CWA EARLIER IN THE DAY.
CHANCE POPS WILL CONTINUE MONDAY NIGHT INTO TUESDAY AS THE FRONT
MOVES THROUGH THE AREA AND AN UPPER TROUGH APPROACHES. EXPECT
MAINLY LIGHT SNOW FROM THIS SYSTEM BUT THERE MAY BE SOME LIGHT RAIN
MIXED IN MONDAY AFTERNOON IN THE SOUTH.
HIGH PRESSURE AND ANOTHER COLD AIRMASS WILL SETTLE INTO THE REGION
BY THE MIDDLE OF THE WEEK. WEAK SYSTEM OVER THE GREAT LAKES COULD
PRODUCE SOME SNOW SHOWERS LATE IN THE PERIOD...SO WENT WITH SLIGHT
POPS LATE WED NIGHT INTO THURSDAY.
&&
.AVIATION /22Z THURSDAY THROUGH TUESDAY/...
MVFR CLOUDS ARE PERSISTING ACROSS OUR AREA THIS AFTERNOON ALTHOUGH
SOME PARTIAL CLEARING AND SOME VFR CIGS ARE JUST OFF TO THE WEST.
SOME OF THIS PARTIAL CLEARING COULD AFFECT THE WESTERN TAF SITES
THROUGH THIS AFTERNOON...BUT GIVEN THE NORTHERLY LOW LEVEL
FLOW...WILL HANG ON TO THE MVFR CIGS THROUGH THE DAY. BETTER
CLEARING PUSHING DOWN INTO NORTHWEST OHIO IS BEING PICKED UP
FAIRLY WELL BY THE 12Z NAM...AND THIS IS FORECAST TO WORK ITS WAY
DOWN TOWARD CENTRAL OHIO THROUGH LATE AFTERNOON AND EARLY EVENING.
HOWEVER...BY THEN THE LOW LEVEL FLOW BEGINS TO SWING AROUND TO THE
SOUTHEAST AND THEN SOUTH OVERNIGHT SO NOT SURE EXACTLY HOW FAR
THE CLEARING WILL MAKE IT. ON THE OTHER HAND...AS THE LOW LEVEL
FLOW DOES BECOME MORE SOUTHERLY...WE COULD ALSO SEE SOME EROSION
OF THE LOW LEVEL CLOUDS ACROSS THE AREA. ALL OF THIS MAKES FOR A
FAIRLY LOW CONFIDENCE CLOUD FORECAST TONIGHT. WITH BOTH THE NAM
AND LATEST RAP HANGING ON TO SOME LOW LEVEL MOISTURE THROUGH MUCH
OF THE NIGHT...HAVE OPTED TO KEEP THINGS PESSIMISTIC AND HOLD ON
TO SOME MVFR CIGS THROUGH THE NIGHT. ON THE FLIP OF THAT...IF WE
DO GET SOME CLEARING...WE COULD SEE SOME MVFR BR DEVELOP LATER
TONIGHT GIVEN THE LIGHT WINDS.
OUTLOOK...MVFR/IFR CEILINGS AND VISIBILITIES POSSIBLE FRIDAY
NIGHT INTO SATURDAY NIGHT AND THEN AGAIN MONDAY AFTERNOON INTO
TUESDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...JDR
NEAR TERM...JDR
SHORT TERM...JDR
LONG TERM...KURZ
AVIATION...JGL
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
154 PM EST THU DEC 27 2012
.SYNOPSIS...
LOW PRESSURE SYSTEM EXITS EAST TODAY. ANOTHER LOW PRESSURE SYSTEM
FRIDAY NIGHT AND SATURDAY...WITH MORE MIXED PRECIPITATION...CHANGING
TO SNOW OVERNIGHT SATURDAY AND SUNDAY.
&&
.NEAR TERM /THROUGH FRIDAY/...
UPDATE...
NO CHANGES THIS AFTERNOON TO PREVIOUS GRIDS.
PREVIOUS DISCUSSION...
RADAR AND MODELS SHOWING LIGHT SNOW OR FREEZING DRIZZLE MOVING INTO
THE EASTERN MOUNTAINS WHILE DIMINISHING ACROSS THE WESTERN HALF OF
THE AREA THIS MORNING. LOW CLOUDS WILL PERSIST OVER A SHALLOW
SATURATED LAYER TODAY...LIFTING TONIGHT. HOWEVER...HIGH LEVEL
CLOUDS ASSOCIATED WITH A FAR AWAY SYSTEM WILL COVER PORTIONS OF OUR
SKIES THROUGH THIS EVENING.
VERY COLD AIR CONTINUES TO FILTER IN UNDER WEST NORTHWEST FLOW WITH
H850 TEMPS WARMING FROM MINUS 9C TO MINUS 5C BY 18Z THIS AFTERNOON
AND TONIGHT. THEREFORE...WITH CLOUDS EXPECTED AND VERY COLD AIR MASS
IN PLACE...TODAYS TEMPERATURES WILL REMAIN AT OR BELOW
FREEZING...EXCEPT FOR POCKETS JUST ABOVE OVER THE LOWLANDS. THESE
LOW TEMPERATURES WILL KEEP ANY WET SURFACE FROZEN...TO PRODUCE BLACK
ICE WHERE WATER USUALLY DRAINS FROM SLOPES...AND ON EXPOSED BRIDGES
AND OVERPASSES. DRIVERS SHOULD EXERCISE CAUTION WHEN TRAVELING
TODAY.
FOR TONIGHT...DRIER CONDITIONS WITH LESS CLOUDS. LOWS GENERALLY IN
THE MID 20S LOWLANDS...RANGING TO THE TEENS HIGHER ELEVATIONS.
HOWEVER...WINDS WILL DIMINISH TONIGHT...KEEPING SIMILAR WINDCHILL AS
TODAY.
GUSTY WINDS WILL PRODUCE WINDCHILL IN THE 20S LOWLANDS...RANGING
INTO NEAR ZERO AT THE HIGHEST PEAKS NORTHEAST MOUNTAINS.
A WIND WIND ADVISORY REMAINS IN EFFECT FOR POCAHONTAS COUNTY THROUGH
AT LEAST 1 PM THIS AFTERNOON.
WENT WITH A BLEND OF THE GMOS AND RUC MODELS FOR TEMPERATURES
THROUGH THE PERIOD.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
AN UPPER LEVEL TROUGH WILL USHER IN THE NEXT SNOW PRODUCING SYSTEM
EARLY ON SATURDAY MORNING. PRECIPITATION WILL START OUT AS RAIN IN
THE SOUTH AND PERHAPS SNOW IN THE NORTH SATURDAY MORNING BUT
TEMPERATURES WILL REBOUND ABOVE FREEZING DURING THE DAY SATURDAY
AS SNOW IN THE NORTH CHANGES OVER TO RAIN BEFORE SWITCHING BACK TO
ALL SNOW AGAIN SATURDAY NIGHT. A COLD AIR MASS WILL THEN SETTLE
OVER THE AREA WITH UPSLOPE WINDS HELPING TO ENHANCE ACCUMULATIONS
OVERNIGHT SATURDAY. ALL SAID AND DONE...WE MAY SEE 1 TO 3 INCHES
IN MOST LOCATIONS MAYBE A TAD MORE OR LESS WHILE THE MOUNTAINS
WILL SEE 2 TO 4 INCHES. AS ALWAYS...FOR ACCUMULATING SNOW...WE
WILL HAVE TO WATCH THE BOUNDARY LAYER THERMODYNAMICS TO SEE IF
ENOUGH COLD AIR MAKES IT IN EARLY ENOUGH TO COINCIDE WITH THE
HEAVIER PRECIPITATION.
BY SUNDAY...MOST OF THE MOISTURE EXITS THE FORECAST AREA AND
SKIES WILL BEGIN TO CLEAR SETTING THE STAGE FOR A COLD NIGHT WHERE
TEMPERATURES WILL DIP INTO THE TEENS IN MANY LOCATIONS AND LOWER
TEENS IN THE MOUNTAINS.
&&
.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
MODELS SHOWING AN UPSLOPE EVENT DEVELOPING SATURDAY NIGHT AND
CONTINUING ON SUNDAY BEHIND A LOW PRESSURE SYSTEM. HIGH PRESSURE
THEN BUILDS IN SUNDAY NIGHT. MODELS THEN DIVERGE CONSIDERABLY ON
SOLUTIONS FOR MONDAY THROUGH WEDNESDAY. USED A BLEND OF THE GEFS AND
ECMWF ENSEMBLE MEANS DURING THIS PERIOD...WITH SLIGHTLY MORE
EMPHASIS ON THE ECMWF ENSEMBLE MEAN.
&&
.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
MVFR CEILINGS WILL BE SLOW TO DISSOLVE AS THE WEAK NORTHWEST FLOW
EVENT WINDS DOWN INTO TONIGHT. CKB AND EKN WILL LIKELY BE THE LAST
TERMINALS TO EMERGE INTO VFR CEILINGS. CARRYING BRIEF IFR IN THE
NORTHEAST MOUNTAINS...WHICH WILL IMPROVE ACCORDINGLY WITH
DECREASING POPS.
NORTHWEST WINDS ALSO SUBSIDE INTO THIS EVENING...AND WILL GET ALL
SITES BELOW 12KTS BY LATER THIS EVENING. LOWLAND AREAS TO GO CALM
BEFORE DAWN.
VFR EXPECTED THURSDAY AS HIGH PRESSURE SETTLES IN. CLOUD COVER
WILL VARY. SURFACE FLOW WILL BE LIGHT AND VARIABLE DUE TO THE HIGH
PRESSURE SYSTEM PASSING THROUGH THE AREA.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z FRIDAY...
FORECAST CONFIDENCE: MEDIUM.
ALTERNATE SCENARIOS: DURATION OF MVFR CEILINGS MAY VARY BY A
COUPLE OF HOURS EITHER WAY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 18 19 20 21 22 23 00 01 02 03 04 05
EST 1HRLY 13 14 15 16 17 18 19 20 21 22 23 00
CRW CONSISTENCY L L L L L L L L L L L M
HTS CONSISTENCY H H H M M M H H H H H H
BKW CONSISTENCY L L L L L L L L L L M M
EKN CONSISTENCY L L L L L L M L L M L L
PKB CONSISTENCY H H H M L L L L L L L L
CKB CONSISTENCY L L L L L L L L L L L L
AFTER 18Z FRIDAY...
IFR POSSIBLE IN SNOW SATURDAY INTO SUNDAY...ESPECIALLY IN THE
MOUNTAINS.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...WIND ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR WVZ046.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...ARJ/50
NEAR TERM...ARJ/26
SHORT TERM...JW
LONG TERM...RPY
AVIATION...26
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
1256 PM EST THU DEC 27 2012
.SYNOPSIS...
LOW PRESSURE SYSTEM EXITS EAST TODAY. ANOTHER LOW PRESSURE SYSTEM
FRIDAY NIGHT AND SATURDAY...WITH MORE MIXED PRECIPITATION...CHANGING
TO SNOW OVERNIGHT SATURDAY AND SUNDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
UPDATE...
NO CHANGES THIS AFTERNOON TO PREVIOUS GRIDS.
PREVIOUS DISCUSSION...
RADAR AND MODELS SHOWING LIGHT SNOW OR FREEZING DRIZZLE MOVING INTO
THE EASTERN MOUNTAINS WHILE DIMINISHING ACROSS THE WESTERN HALF OF
THE AREA THIS MORNING. LOW CLOUDS WILL PERSIST OVER A SHALLOW
SATURATED LAYER TODAY...LIFTING TONIGHT. HOWEVER...HIGH LEVEL
CLOUDS ASSOCIATED WITH A FAR AWAY SYSTEM WILL COVER PORTIONS OF OUR
SKIES THROUGH THIS EVENING.
VERY COLD AIR CONTINUES TO FILTER IN UNDER WEST NORTHWEST FLOW WITH
H850 TEMPS WARMING FROM MINUS 9C TO MINUS 5C BY 18Z THIS AFTERNOON
AND TONIGHT. THEREFORE...WITH CLOUDS EXPECTED AND VERY COLD AIR MASS
IN PLACE...TODAYS TEMPERATURES WILL REMAIN AT OR BELOW
FREEZING...EXCEPT FOR POCKETS JUST ABOVE OVER THE LOWLANDS. THESE
LOW TEMPERATURES WILL KEEP ANY WET SURFACE FROZEN...TO PRODUCE BLACK
ICE WHERE WATER USUALLY DRAINS FROM SLOPES...AND ON EXPOSED BRIDGES
AND OVERPASSES. DRIVERS SHOULD EXERCISE CAUTION WHEN TRAVELING
TODAY.
FOR TONIGHT...DRIER CONDITIONS WITH LESS CLOUDS. LOWS GENERALLY IN
THE MID 20S LOWLANDS...RANGING TO THE TEENS HIGHER ELEVATIONS.
HOWEVER...WINDS WILL DIMINISH TONIGHT...KEEPING SIMILAR WINDCHILL AS
TODAY.
GUSTY WINDS WILL PRODUCE WINDCHILL IN THE 20S LOWLANDS...RANGING
INTO NEAR ZERO AT THE HIGHEST PEAKS NORTHEAST MOUNTAINS.
A WIND WIND ADVISORY REMAINS IN EFFECT FOR POCAHONTAS COUNTY THROUGH
AT LEAST 1 PM THIS AFTERNOON.
WENT WITH A BLEND OF THE GMOS AND RUC MODELS FOR TEMPERATURES
THROUGH THE PERIOD.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
FRIDAY A SHORT BREAK IN THE ACTIVE WEATHER PATTERN TAKES PLACE WITH
S/W RIDGE OVERHEAD AT 12Z QUICKLY MOVING EAST WITH UPPER FLOW
TURNING SOUTHWESTERLY IN ADVANCE OF THE NEXT RAPIDLY-APPROACHING
UPPER LEVEL TROUGH MOVING ACROSS THE CENTRAL MISS VALLEY AREA. SFC
HIGH PRESSURE SLIDES OFF TO THE EAST WITH RETURN SOUTHERLY FLOW.
OVERALL A PARTLY CLOUDY DAY GENERALLY SPEAKING WITH MORE CLOUDS TO
START THE DAY AND CLOUDS INCREASING ACROSS THE WEST BY END OF DAY.
LOOKS LIKE A DECENT TEMPERATURE GRADIENT FORMS ACROSS THE AREA AS A
WARM FRONTAL FEATURE SETS UP ROUGHLY FROM POCAHONTAS COUNTY WSW-WARD
TOWARDS HTS BY FRI MID-AFTERNOON. FAR NW ZONES WHERE RESIDUAL SNOW
COVER REMAINS WILL ONLY REACH THE MID/UPPER 30S WHEREAS FAR SOUTHERN
ZONES...WHERE 925MB TEMPS ARE PROGGED TO REACH AROUND 5.5C TO
6C...WILL PUSH 50 DEGREES AND POTENTIALLY INTO THE LOWER 50S. FRIDAY
NIGHT...LARGE SCALE ASCENT OVERSPREADS THE FORECAST AREA FROM WEST
TO EAST AS AFOREMENTIONED TROUGH CONTINUES TOWARD THE AREA WITH AXIS
ENTERING THE CWA AROUND 12Z SAT WITH SFC COLD FRONT MOVING INTO CWA
WITH IT. BEST DEEP LAYER MOISTURE WILL BE ALONG AND AHEAD OF SFC
FRONT SO WILL HAVE BEST OVERALL POPS DURING THE OVERNIGHT PERIOD.
MEANWHILE OVERNIGHT THE WARM FRONT QUICKLY LIFTS NORTHWARD WITH
DEVELOPING SFC LOW ACROSS NORTH OF LAKE ERIE IN SW ONTARIO. RAISED
MINS A BIT TO ACCOUNT FOR LLVL WARM ADVECTION AT 850MB...ALBEIT IT
IS RELATIVELY WEAK. AS A RESULT...WILL KEEP THE RAIN/SNOW MIX LINE
NORTH OF THE INTERSTATE 64 CORRIDOR FRI NIGHT/SAT MORNING AND ALL
SNOW ALONG AND NORTH OF A LINE ROUGHLY FROM PKB TO CKB AND ACROSS
THE HIGHER ELEVATIONS. SATURDAY AS THE INITIAL TROUGH AND COLD FRONT
CONTINUE EASTWARD...DEEP LAYER MOISTURE WANES AS DO THE HIGHER POPS.
A SOLID 3-5KFT LLVL OF SATURATION WILL REMAIN...AND AS SUCH SATURDAY
STAYS CLOUDY. MEANWHILE THE UPPER TROUGH DIGS TO THE WEST AGAIN AS
COLD ADVECTION CONTINUES BEHIND FRONT. LONG STORY SHORT...CHANCES
FOR PRECIP DWINDLE SOMEWHAT DURING THE DAY BUT RAMP BACK UP ONCE
AGAIN PARTICULARLY AFTER 21Z SAT AS SECONDARY UPPER TROUGH AXIS
APPROACHES FROM THE WEST AND MEAGER LLVL MOISTURE DEEPENS A BIT.
AIDING IN PRECIP PRODUCTION WILL BE THE STEEPENING LLVL LAPSE RATES
WITH THE UPPER TROUGH APPROACH WHICH MAY ADD A LEVEL OF CONVECTIVE
ENHANCEMENT. BY SATURDAY EVENING AND SATURDAY NIGHT A SECONDARY PUSH
OF COLD ADVECTION INTO THE AREA SHOULD RESULT IN A CHANGEOVER TO ALL
SNOW FOR THE ENTIRE AREA BY 03Z-06Z SUN. SNOW ACCUMULATIONS ARE
EXPECTED TO REMAIN LIGHT HOWEVER...WITH A DUSTING TO PERHAPS AROUND
A HALF INCH FOR MOST LOWLAND LOCATIONS AND ONE TO TWO INCHES FOR
ELEVATIONS ABOVE ABOUT 2.5KFT.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
MODELS SHOWING AN UPSLOPE EVENT DEVELOPING SATURDAY NIGHT AND
CONTINUING ON SUNDAY BEHIND A LOW PRESSURE SYSTEM. HIGH PRESSURE
THEN BUILDS IN SUNDAY NIGHT. MODELS THEN DIVERGE CONSIDERABLY ON
SOLUTIONS FOR MONDAY THROUGH WEDNESDAY. USED A BLEND OF THE GEFS AND
ECMWF ENSEMBLE MEANS DURING THIS PERIOD...WITH SLIGHTLY MORE
EMPHASIS ON THE ECMWF ENSEMBLE MEAN.
&&
.AVIATION /17Z THURSDAY THROUGH MONDAY/...
MVFR CEILINGS WILL BE SLOW TO DISSOLVE AS THE WEAK NORTHWEST FLOW
EVENT WINDS DOWN INTO TONIGHT. CKB AND EKN WILL LIKELY BE THE LAST
TERMINALS TO EMERGE INTO VFR CEILINGS. CARRYING BRIEF IFR IN THE
NORTHEAST MOUNTAINS...WHICH WILL IMPROVE ACCORDINGLY WITH
DECREASING POPS.
NORTHWEST WINDS ALSO SUBSIDE INTO THIS EVENING...AND WILL GET ALL
SITES BELOW 12KTS BY LATER THIS EVENING. LOWLAND AREAS TO GO CALM
BEFORE DAWN.
VFR EXPECTED THURSDAY AS HIGH PRESSURE SETTLES IN. CLOUD COVER
WILL VARY. SURFACE FLOW WILL BE LIGHT AND VARIABLE DUE TO THE HIGH
PRESSURE SYSTEM PASSING THROUGH THE AREA.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z FRIDAY...
FORECAST CONFIDENCE: MEDIUM.
ALTERNATE SCENARIOS: DURATION OF MVFR CEILINGS MAY VARY BY A
COUPLE OF HOURS EITHER WAY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 18 19 20 21 22 23 00 01 02 03 04 05
EST 1HRLY 13 14 15 16 17 18 19 20 21 22 23 00
CRW CONSISTENCY L L L L L L L L L L L M
HTS CONSISTENCY H H H M M M H H H H H H
BKW CONSISTENCY L L L L L L L L L L M M
EKN CONSISTENCY L L L L L L M L L M L L
PKB CONSISTENCY H H H M L L L L L L L L
CKB CONSISTENCY L L L L L L L L L L L L
AFTER 18Z FRIDAY...
IFR POSSIBLE IN SNOW SATURDAY INTO SUNDAY...ESPECIALLY IN THE
MOUNTAINS.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...WIND ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR WVZ046.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...ARJ/50
NEAR TERM...ARJ/26
SHORT TERM...50
LONG TERM...RPY
AVIATION...26
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
1251 PM EST THU DEC 27 2012
.SYNOPSIS...
WEAK HIGH PRESSURE WILL BUILD INTO THE OHIO VALLEY FROM THE GREAT
LAKES TODAY. AHEAD OF AN UPPER LEVEL TROUGH...LOW PRESSURE WILL
NOSE INTO THE OHIO VALLEY FRIDAY NIGHT FROM THE LOWER MISSISSIPPI
VALLEY. THE LOW WILL EXIT ON SATURDAY BUT LINGERING FLURRIES
UNDERNEATH A LARGE UPPER LEVEL TROUGH WILL PERSIST INTO THE
WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
SATELLITE IMAGES SHOWING A FEW THIN SPOTS OR POSSIBLE BREAKS
ACROSS PARTS OF EASTERN INDIANA/FAR WESTERN OHIO...BUT IN GENERAL
CLOUDS REMAIN WIDESPREAD ACROSS THE REGION. THE 12Z ILN SOUNDING IS
INDICATING A FAIRLY DEEP MOIST LAYER IN THE LOW LEVELS AND WITH
CONTINUED CYCLONIC LOW LEVEL FLOW THROUGH AT LEAST MID
AFTERNOON...WOULD EXPECT A FAIR AMOUNT OF CLOUDS TO HANG IN
THROUGH THE DAY. DESPITE THE NORTHERLY LOW LEVEL FLOW...TEMPERATURE
ADVECTION REMAINS MOSTLY NEUTRAL TODAY BUT WITH THE CLOUDS AND
SOME SNOW PACK...DO NOT EXPECT MUCH TEMPERATURE RECOVERY TODAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/...
CLOUD COVER WILL SEE SOME BREAKS TONIGHT AS HIGH PRESSURE SETTLES
OVER SOUTHWEST OHIO. COMBINED WITH THE FRESH SNOW PACK AND THE
LIGHTER WINDS FROM AFOREMENTIONED HIGH...TEMPERATURES TONIGHT WILL
BOTTOM OUT IN THE TEENS FOR MUCH OF THE REGION. IF SKIES WERE TO
CLEAR OUT ENTIRELY...TEMPERATURES WILL NEED TO BE ADJUSTED
DOWNWARDS.
LOW PRESSURE FROM THE GULF WILL SKIM SOUTHEAST OF THE REGION AGAIN
ON FRIDAY NIGHT AND EARLY SATURDAY. ENOUGH WARM AIR MAY BE PULLED
IN WITH IT TO HAVE A RAIN/SNOW MIX AT THE ONSET OVER PORTIONS OF
KENTUCKY. OTHERWISE THE PREDOMINANT WEATHER TYPE FOR THIS SYSTEM
WILL BE SNOW. THE SYSTEM WILL BE WELL AHEAD OF THE UPPER LEVEL
TROUGH AND NOT NEARLY AS ENERGETIC AS LAST NIGHTS SYSTEM. ANY
BRIEF SHOT OF SNOW EARLY ON SATURDAY WILL TAPER TO FLURRIES BY THE
AFTERNOON. THESE FLURRIES AND LIGHT SNOW SHOWERS WILL REMAIN
POSSIBLE FOR THE REMAINDER OF THE WEEKEND AS A LARGE UPPER LEVEL
TROUGH PROVIDES SUFFICIENT LIFT WITH AMPLE CLOUD COVER ALREADY IN
PLACE.
TEMPERATURES WILL TRY TO MAKE A REBOUND BUT BE HAMPERED BY CLOUDS
AND SNOW PACK. OVERNIGHT LOWS WILL BE HARD PRESSED TO SEE RUNAWAY
COLD TEMPERATURES DUE TO EXPECTED CLOUD COVER.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
CLOUDS WILL BEGIN TO DECREASE A BIT ON SUNDAY AS HIGH PRESSURE
OVER THE LOWER MS VALLEY MOVES NORTHEAST INTO THE REGION. THIS
SYSTEM WILL PROVIDE QUIET WEATHER THROUGH MONDAY MORNING. THE GFS
AND ECMWF THEN BEGIN TO DIVERGE SIGNIFICANTLY FOR THE REMAINDER OF
THE EXTENDED PERIOD...AND GEFS ENSEMBLE CLUSTERS SHOW CONSIDERABLE
SPREAD. A COLD FRONT IS PROGGED TO PUSH THROUGH THE AREA LATE
MONDAY NIGHT INTO TUESDAY...BRINGING THE NEXT CHANCE FOR SOME
PRECIP. FORECAST SOUNDINGS INDICATE THE ONSLAUGHT OF PRECIPITATION
MONDAY EVENING MAY BEGIN AS RAIN...SNOW...OR A MIX SOUTH OF THE
OHIO RIVER BEFORE COLDER TEMPERATURES CHANGE IT TO LIGHT SNOW.
ELSEWHERE... EXPECT JUST CHANCE/SLIGHT CHANCE FOR LIGHT SNOW AT
TIMES THROUGH WEDNESDAY.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
MVFR CLOUDS ARE PERSISTING ACROSS OUR AREA THIS AFTERNOON ALTHOUGH
SOME PARTIAL CLEARING AND SOME VFR CIGS ARE JUST OFF TO THE WEST.
SOME OF THIS PARTIAL CLEARING COULD AFFECT THE WESTERN TAF SITES
THROUGH THIS AFTERNOON...BUT GIVEN THE NORTHERLY LOW LEVEL
FLOW...WILL HANG ON TO THE MVFR CIGS THROUGH THE DAY. BETTER
CLEARING PUSHING DOWN INTO NORTHWEST OHIO IS BEING PICKED UP
FAIRLY WELL BY THE 12Z NAM...AND THIS IS FORECAST TO WORK ITS WAY
DOWN TOWARD CENTRAL OHIO THROUGH LATE AFTERNOON AND EARLY EVENING.
HOWEVER...BY THEN THE LOW LEVEL FLOW BEGINS TO SWING AROUND TO THE
SOUTHEAST AND THEN SOUTH OVERNIGHT SO NOT SURE EXACTLY HOW FAR
THE CLEARING WILL MAKE IT. ON THE OTHER HAND...AS THE LOW LEVEL
FLOW DOES BECOME MORE SOUTHERLY...WE COULD ALSO SEE SOME EROSION
OF THE LOW LEVEL CLOUDS ACROSS THE AREA. ALL OF THIS MAKES FOR A
FAIRLY LOW CONFIDENCE CLOUD FORECAST TONIGHT. WITH BOTH THE NAM
AND LATEST RAP HANGING ON TO SOME LOW LEVEL MOISTURE THROUGH MUCH
OF THE NIGHT...HAVE OPTED TO KEEP THINGS PESSIMISTIC AND HOLD ON
TO SOME MVFR CIGS THROUGH THE NIGHT. ON THE FLIP OF THAT...IF WE
DO GET SOME CLEARING...WE COULD SEE SOME MVFR BR DEVELOP LATER
TONIGHT GIVEN THE LIGHT WINDS.
OUTLOOK...MVFR/IFR CEILINGS AND VISIBILITIES POSSIBLE FRIDAY
NIGHT INTO SATURDAY NIGHT AND THEN AGAIN MONDAY AFTERNOON INTO
TUESDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...FRANKS
NEAR TERM...JGL
SHORT TERM...FRANKS
LONG TERM...KURZ
AVIATION...JGL
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
1051 AM MST THU DEC 27 2012
.DISCUSSION...UPPER LEVEL ANALYSIS HAS LARGE TROF OVER THE WESTERN
AND CENTRAL CONUS WITH CLOSED UPPER LOW IN NORTHERN NEBRASKA.
REGIONAL RADARS HAVE WIDESPREAD AREA OF SNOW ACROSS SOUTH DAKOTA
AND NEBRASKA ASSOCIATED WITH THIS LOW. SNOWFALL RATES HAVE BEEN
LIGHT...WITH GENERALLY 1 TO 2 INCHES OF SNOW ACCUMULATION SO FAR.
CURRENT SURFACE ANALYSIS HAS ARCTIC HIGH OVER THE GREAT LAKES AREA
WITH LOW PRESSURE OVER THE CENTRAL ROCKIES. WEAK INVERTED TROF
EXTENDS FROM THE COLORADO ROCKIES INTO NORTHEAST WYOMING. TEMPS
ARE MAINLY IN THE SINGLE DIGITS TO LOW TEENS. EAST TO SOUTHEAST
WINDS HAVE SWITCHED TO NORTH FROM FAR WESTERN SOUTH DAKOTA INTO
NORTHEAST WYOMING.
ACCUMULATING SNOWS HAVE ENDED ACROSS NORTHEAST WYOMING AND FAR
WESTERN SOUTH DAKOTA...WITH LIGHT SNOW CONTINUING FURTHER EAST.
UPPER LOW IS STARTING TO TAKE A JOG TO THE NORTHEAST...WHICH THE
LATEST RAP GUIDANCE IS NOW SHOWING. NOT MUCH CHANGE TO GOING
FORECAST THOUGH...AS DRIER AIR IS INVADING WESTERN PORTIONS OF THE
FORECAST AREA PRETTY QUICKLY. RADAR ECHOES HAVE SHOWN A MARKED
DECREASE OVER THE LAST COUPLE HOURS IN FAR WESTERN SOUTH DAKOTA.
STILL EXPECT ANOTHER INCH OR TWO OF SNOW ACROSS FAR SOUTH CENTRAL
SOUTH DAKOTA THIS AFTERNOON AND EVENING BEFORE SYSTEM FINALLY
SHIFTS EAST. UPDATES HAVE BEEN SENT.
&&
.AVIATION...18Z TAFS
-SN OVER WESTERN SD WILL SLOWLY MOVE EAST AND WANE THROUGH EARLY
THIS EVENING...BUT EXPECT IFR/MVFR CIGS/VSBYS WITH THE -SN. VFR
CONDITIONS WILL SLOWLY WORK ACROSS THE AREA FROM WEST TO EAST
TONIGHT...BUT POCKETS OF MVFR CIGS WILL LINGER OVER MUCH OF THE AREA
DUE TO BOUNDARY LAYER MOISTURE.
&&
.PREV DISCUSSION... /ISSUED 230 AM MST THU DEC 27 2012/
DISCUSSION...WATER VAPOR IMAGERY SHOWS BROAD CYCLONIC FLOW ACROSS
THE WESTERN HALF OF THE CONUS...WITH AN UPPER LOW CROSSING EASTERN
WYOMING INTO THE NEBRASKA PANHANDLE. SURFACE ANALYSIS SHOWS LOW
PRESSURE OVER THE COLORADO PLAINS WITH THE STRONG TEMP GRADIENT OF A
DRIFTING FRONT BOUNDARY STRETCHING FROM THE COLORADO LOW THROUGH
EASTERN WYOMING INTO CENTRAL MONTANA. KUDX RADAR SHOWS SNOW PUSHING
ACROSS THE AREA WITH THE STRONGEST RETURNS OVER THE BLACK HILLS AREA
THROUGH BUTTE COUNTY.
SNOW WILL CONTINUE TODAY AS THE SYSTEM PUSHES THROUGH. THE NEBRASKA
UPPER LOW WILL MOVE TO NEAR THE SOUTH CENTRAL SD BORDER EARLY THIS
MORNING...WITH A HEAVIER BAND OF SNOW CROSSING THE AREA AND THEN
EAST OF THE CWA TOWARD LATE MORNING. IT STILL LOOKS LIKE THE
FORECAST AREA WILL GENERALLY SEE ONE TO THREE INCHES OF
ACCUMULATION. SOME OF THE LOCATIONS NEAR THE SOUTHERN BLACK HILLS
MAY SEE ACCUMULATIONS CLOSER TO THE ONE INCH RANGE.
QUIETER WEATHER IS EXPECTED FRIDAY AND SATURDAY AS UPPER RIDGING
BUILDS ACROSS THE AREA. CLOUDY SKIES WILL PERSIST INTO FRIDAY...BUT
GRADUALLY DECREASING THROUGH THE DAY AS DRIER AIR PUSHES IN FROM THE
WEST. WARM AIR ADVECTION WILL BEGIN LATE FRIDAY...WITH HIGHS IN THE
UPPER TEENS TO MID 20S. CLOUDS WILL CLEAR OUT BY SUNRISE SATURDAY
MORNING...WITH PLENTY OF SUNSHINE IN STORE FOR THE DAY. WARM AIR
ADVECTION WILL STRENGTHEN WITH HIGHS REACHING THE MID 20S TO MID 30S.
EXTENDED...MODELS IN DECENT AGREEMENT WITH LONG WAVE TROF OVER THE
GREAT LAKES AND UPPER RIDGE OVER NORTHERN PLAINS WILL RESULT IN A
WARMING TREND ACROSS THE NORTHERN PLAINS. A FEW GEFS MEMBERS STILL
SHOW SHALLOW ARCTIC INTRUSION INTO WESTERN SOUTH DAKOTA EARLY NEXT
WEEK...BUT A MAJORITY OF THE MEMBERS HAVE BEEN TRENDING WARMER WITH
EACH MODEL RUN. WILL MAINTAIN DRY FORECAST WITH TEMPERATURES WARMING
TO NEAR AVERAGE.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&
$$
SHORT TERM...15
LONG TERM....WFO UNR
AVIATION...HELGESON
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1144 AM CST THU DEC 27 2012
.UPDATE...ADDED SCATTERED FLURRIES FOR THE LAKESHORE COUNTIES
THROUGH THIS EVENING...GIVEN VERY LIGHT REFLECTIVITY RETURNS ON
RADARS. NORTHEAST FETCH AND DELTA T VALUES REMAIN FAVORABLE AS
THEY HAVE BEEN THE PAST FEW DAYS. HOWEVER...THE ISSUE ONCE AGAIN
IS THE LACK OF MOISTURE IN THE DENDRITE GROWTH ZONE.
MESOSCALE MODELS DO SHOW A CONVERGENCE ZONE WITH BROKEN LIGHT QPF
EXTENDING FROM DOWNTOWN CHICAGO NORTHWARD AND OFF SHORE OF THE
LAKESHORE COUNTIES...AND THEN NORTHEAST FROM THERE. THIS AREA
REMAINS OVER THE WATER THROUGH THE REST OF TODAY...WITH SOME
INDICATIONS OF IT COMING ONSHORE IN THE FAR SOUTHEAST COUNTIES
THIS EVENING.
THUS...NOTHING MORE THAN FLURRIES ARE EXPECTED. CLOUDY SKIES WILL
REMAIN THROUGH THE DAY AND EVENING...WITH TEMPERATURES REMAINING
IN THE MID 20S TO AROUND 30.
&&
.AVIATION/18Z TAFS/...EXPECT MVFR/VFR CEILINGS TO REMAIN ACROSS
TAF SITES THIS AFTERNOON AND TONIGHT. WINDS WILL CONTINUE TO
GRADUALLY WEAKEN AS WELL.
LIGHT SNOW WITH MVFR VISIBILITIES/CEILINGS WILL MOVE WEST TO EAST
INTO KMSN BY 11Z FRIDAY...AND THE EASTERN SITES BY 15Z
FRIDAY. MORE STEADY SNOW/VISIBILITIES BELOW ALTERNATE MINIMUMS
WILL REACH KMSN BY 13Z FRIDAY...AND THE EASTERN SITES BY 17Z
FRIDAY. CEILINGS WILL BE IFR CATEGORY.
EXPECT A GENERAL 2 TO 3 INCH ACCUMULATION BY LATE FRIDAY...WITH A
TOTAL OF 3 TO 4 INCHES BY LATER FRIDAY NIGHT.
&&
.MARINE...SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL 00Z FRIDAY
ACROSS THE NEARSHORE WATERS. PRESSURE GRADIENT AND SUBSEQUENT
WINDS CONTINUE TO WEAKEN...AS THE STRONG LOW MOVES INTO COASTAL
NEW ENGLAND. WAVES WILL SUBSIDE AS WELL...FALLING BELOW SMALL
CRAFT ADVISORY LEVELS BY 00Z FRIDAY.
&&
.PREV DISCUSSION... /ISSUED 400 AM CST THU DEC 27 2012/
SHORT TERM...
TODAY-FORECAST CONFIDENCE HIGH
SECONDARY LOW OFF SOUTHERN NEW ENGLAND TAKING OVER ON EAST COAST
STORM AND FLOW OVER LAKE MICHIGAN TURNING MORE NORTHERLY WITH TIME.
WEAK LAKE EFFECT BAND RIGHT ALONG THE RACINE/KENOSHA SHORE HAS YET
TO TRIGGER A FLURRY AT THE KRAC OBSERVATION...AND SEEMS TO BE
SHIFTING OFFSHORE. 4KM MODELS SEEM TO HAVE A BIT OF A STRONG BIAS
ON THIS FEATURE AND HAVE IT TOO FAR WEST.
LATEST LOCAL WSWRF AND HRRR ARE NOT TOO IMPRESSIVE WITH THIS FEATURE
AND KEEP IT MOSTLY OFFSHORE. IT SHOULD BE NOTED THAT THE MODELS
TURN THE FLOW IN THE LOWEST 1-2KM MORE AND MORE NORTHERLY AND
ACTUALLY INCREASE 850 MB TEMPS A BIT THIS MORNING...DECREASING THE
LAKE INSTABILITY AND DELTA TS A BIT FROM ROUGHLY 15 TO ABOUT 13.
THE LAKE EFFECT STRUGGLED THROUGHOUT THE EVENT DUE TO RELATIVELY DRY
AIR IN 850 TO 700 MB LAYER AND A LOW INVERSION HEIGHT THAT WAS OFTEN
DOWN TO 4000 FEET. WILL KEEP SOME LOW POPS NEAR THE KENOSHA/RACINE
LAKE SHORE BUT DO NOT EXPECT MUCH TO HAPPEN.
OTHERWISE EXPECT THE GRADIENT TO WEAKEN TODAY WITH WEAK SURFACE
RIDGE MOVING OVER WISCONSIN. STRATUS STATUS APPEARS TO BE PRIMARY
MESSAGE...AS FOG PRODUCT SHOWS A WESTWARD TREND IN LOW CLOUDS. THIS
IS OPPOSED TO THE TREND THAT I FORECAST LAST NIGHT...WHICH SHOULD
NOT BE SURPRISING FOR THOSE WHO KNOW ME.
PER COORDINATION WITH SURROUNDING OFFICES...WENT WITH MUCH CLOUDIER
FORECAST TODAY AS TIME SECTIONS INDICATE LOW CLOUDS WILL BE TOUGH TO
SCOUR OUT TODAY WITH WEAK FORCING AND DECREASING GRADIENT.
TONIGHT-FORECAST CONFIDENCE HIGH
SATELLITE SHOWS IMPRESSIVE VORTICITY MAXIMUM EMERGING ON THE HIGH
PLAINS IN WESTERN NEBRASKA CURRENTLY. MODELS IN GOOD AGREEMENT IN
MOVING 500 MB CLOSED LOW TO NORTH CENTRAL NEBRASKA THIS AFTERNOON
AND THEN CLOSE TO THE SD/IA/NE BORDER AREA NEAR SIOUX CITY TONIGHT.
WEAK BUT DEEP WARM ADVECTION EXPECTED AHEAD OF THIS FEATURE AND
SHOULD SPREAD ACROSS IOWA TOWARD WISCONSIN LATE TONIGHT. DESPITE
FAIRLY WEAK LIFT THERE IS A RATHER DEEP AND NEARLY SATURATED LAYER
IN THE DENDRITE GROWTH ZONE (-12 TO -18C) WITH THIS SYSTEM WHICH
WOULD ENHANCE SNOW POTENTIAL AND ESPECIALLY SNOW TO LIQUID RATIOS.
THEREFORE WENT WAY ABOVE GUIDANCE IN THE WEST LATE TONIGHT...WHICH
IS SURPRISINGLY LOW GIVEN CONSISTENT HANDLING OF THIS FEATURE BY
GUIDANCE. APPEARS THAT MOS IS LEANING TOWARD THE TENDENCY FOR ASOS
TO STRUGGLE TO MEASURE LIGHT SNOWFALL IN EVENTS LIKE THIS.
FRIDAY AND FRIDAY NIGHT...FORECAST CONFIDENCE HIGH.
SNOW WILL OVERSPREAD ALL OF SOUTHERN WI FRI MORNING AND TAPER OFF
FROM WEST TO EAST FRIDAY EVENING. STORM TOTAL SNOW AMOUNTS FROM LATE
THU NIGHT THROUGH FRIDAY EVENING SHOULD BE IN THE 2 TO 4 INCH
RANGE...POSSIBLY HIGHER FROM THE DELLS TO MADISON TO RACINE AND THE
OTHER LAKESHORE COUNTIES IF LAKE ENHANCEMENT OCCURS. MAJORITY OF THE
SNOW SHOULD FALL IN AN 8-HOUR PERIOD ON FRIDAY...AFFECTING THE
MORNING RUSH IN MADISON AND THE EVENING RUSH IN BOTH MADISON AND
MILWAUKEE. A LOW-END WINTER WEATHER ADVISORY WILL NEED TO BE
CONSIDERED...BUT WILL HIGHLIGHT THE RUSH HOUR HEADACHE WITH A
SPECIAL WEATHER STATEMENT FOR NOW.
OVERALL THE SYSTEM DYNAMICS ARE NOT OVERLY IMPRESSIVE...BUT THE
SLOW-MOVING NATURE OF THE UPPER TROUGH AND THE SUBTLE AND PERSISTENT
FORCING WILL BE ENOUGH TO PRODUCE SEVERAL INCHES OF FLUFFY SNOW OVER
ROUGHLY AN 18-HR PERIOD. WINDS WILL BE LIGHT OUT OF THE EAST ON
FRIDAY. THE STRONGEST FORCING WILL BE ASSOCIATED WITH A VORT MAX
ROLLING ACROSS IOWA AND SOUTHERN WI FRI. BEST OMEGA VALUES WILL
GENERALLY BE JUST BELOW THE DENDRITIC GROWTH ZONE /DGZ/ FOR MOST OF
THE PERIOD. HOWEVER... THE DGZ WILL BE FAIRLY DEEP AT AROUND 5K TO
7K FT. THERE SHOULD BE AT LEAST A FEW-HOUR PERIOD OF TIME WHERE
THERE IS DECENT OMEGA WITHIN THE DEEP DGZ LEADING TO EFFICIENT SNOW
ACCUMULATION. THE NAM SHOWS THIS OCCURRING AROUND 18Z AT MSN AND 20Z
AT MKE.
SEVERAL OF THE MESOSCALE MODELS ARE SHOWING A MID-LAKE LAKE EFFECT
BAND MOVE ONSHORE WITH THE EASTERLY WINDS...WITH A FEW OF THEM
DEVELOPING A MESO-LOW OVER SOUTHERN LAKE MICHIGAN. AS A
RESULT...THESE MODELS SEEM TO BE OVER-DOING THE QPF AND SNOW AMOUNTS
NEAR THE LAKESHORE. BUT IT NEEDS TO BE NOTED THAT SOME SUBTLE LAKE
ENHANCEMENT WILL BE POSSIBLE WITH THE 13C-18C DELTA T FOR THE
LAKESHORE COUNTIES.
SATURDAY...FORECAST CONFIDENCE MEDIUM.
THE UPPER TROUGH WILL STILL BE OVER THE GREAT LAKES REGION AND THE
LOW LEVEL MOISTURE WILL LINGER SO KEPT MENTION OF FLURRIES THROUGH
THE DAY AND CLOUDS THROUGH THE DAY AND NIGHT. WEAK COLD AIR
ADVECTION DURING THIS TIME...BUT CLOUD COVER WILL KEEP TEMPS
MODERATED...WITH HIGHS IN THE UPPER 20S.
LONG TERM...
SUNDAY THROUGH THURSDAY...FORECAST CONFIDENCE...MEDIUM.
SOME SUNSHINE IS EXPECTED ON SUNDAY. LOW PRESSURE WILL TRACK ACROSS
LAKE SUPERIOR SUN NIGHT AND THE ASSOCIATED COLD FRONT WILL CROSS
SOUTHERN WI MON MORNING...USHERING COLDER AIR INTO THE AREA. A
PERIOD OF CLOUDS WILL BE LIKELY WITH THIS FRONTAL PASSAGE.
ANOTHER WEAK WAVE WILL MOVE THROUGH THE UPPER GREAT LAKES AREA WED
MORNING WHICH MAY PRODUCE SOME LIGHT SNOW OR FLURRIES. THE ECMWF IS
DRY AND THE GFS SHOWS VERY LIGHT QPF.
AVIATION/12Z TAFS/...
TIME HEIGHT SECTIONS FROM BOTH GFS AND NAM NOW SHOW STRATUS
REMAINING IN PLACE IN SOUTHEAST THROUGH TONIGHT. SHOULD BE NO WORSE
THAN MVFR AND LIKELY TO IMPROVE A TAD TO LOWER END VFR CEILINGS
LATER TODAY INTO TONIGHT. MOST UNCERTAINTY IS KMSN...WHERE THE
GUIDANCE SHOWS THE STRATUS DECK VANISHING WITHIN THE NEXT FEW
HOURS.
FOG PRODUCT TRENDS AND SURFACE OBSERVATIONS DO NOT SUPPORT THIS
TREND. THUS...WILL EXTEND THE VFR CEILING A BIT LONGER INTO THE
MIDDAY HOURS BEFORE GOING WITH SCATTERED LOWER DECK.
REGARDLESS OF WHAT HAPPENS TO LOWER DECK EXPECT MID LEVEL CLOUDS TO
MOVE IN QUICKLY AROUND 00Z AND GRADUALLY LOWER WITH A GOOD THREAT
FOR VIRGA/SNOW ALOFT IN THE 06Z TO 12Z PERIOD...ESPECIALLY IN KMSN.
SNOW SHOULD START AROUND 12Z IN KMSN AND THEN SPREAD TO SOUTHEAST
WI STAFFS AROUND 18Z. PROLONGED IFR CONDITIONS LIKELY WITH THE
LIGHT SNOW.
MARINE...
NORTH TO NORTHWEST WINDS ARE NEAR SMALL CRAFT LEVELS NOW BUT SHOULD
GRADUALLY DIMINISH TODAY. WITH OFFSHORE FLOW THE WAVES ARE ALREADY
DIMINISHING BUT SHOULD REMAIN ABOVE 4 FEET UNTIL LATE AFTERNOON.
PER COORDINATION WITH GRB AND LOT WILL END SMALL CRAFT ADVISORY
ABOUT 9 HOURS EARLIER THAN PREVIOUS FORECASTS...AT 00Z TODAY.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 6 PM CST THIS EVENING FOR LMZ643>646.
&&
$$
UPDATE...WOOD
TODAY/TONIGHT AND AVIATION/MARINE...CRAVEN
FRIDAY THROUGH WEDNESDAY...MRC