Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 02/21/13
AREA FORECAST DISCUSSION
NWS EUREKA CA
300 PM PST WED FEB 20 2013
.SYNOPSIS...A COLD UPPER TROUGH WILL MAINTAIN COOL TEMPERATURES FOR
THE REMAINDER OF THE WEEK...WITH BOUTS OF LIGHT RAIN OR SNOW
POSSIBLE NEAR THE OR/CA BORDER.
&&
.DISCUSSION...SKIES ARE MOSTLY CLEAR ACROSS THE AREA THIS AFTERNOON
WITH LIGHT WINDS AND DRIER AIR. ANOTHER WEAK FRONT IS CURRENTLY JUST
OFF THE COAST AND WILL GRADUALLY MOVE INTO THE COAST LATE TONIGHT.
PRECIPITATION WITH THIS FEATURE WILL BE CONFINED TO MAINLY LIGHT
RAIN NORTH OF ORICK AND SOME LIGHT SNOW ABOVE 2500 FEET NORTH OF HWY
299. THE NEXT MORE SIGNIFICANT CHANCE OF PRECIP WILL BE FRI NIGHT
WHEN A STRONG FRONT APPROACHES FROM THE WEST. GFS IS STILL SHOWING
NEARLY A HALF INCH OF PRECIP ALONG THE NORTH COAST BUT THE NAM IS MUCH
LIGHTER WITH CLOSER TO ONLY A TENTH. GIVEN THE WIDE DISPARITY WILL
SHOOT FOR SOMEWHERE IN THE MIDDLE THINKING A QUARTER INCH IS LIKELY.
THE FORECAST PERIOD WILL CONTINUE TO BE DOMINATED BY FAIRLY WEAK
FRONTAL SYSTEMS DIVING SE INTO THE AREA BRINGING THE BEST POPS TO N
PORTIONS OF THE FORECAST AREA. NEAR TO ABOVE NORMAL POPS ARE
EXPECTED OVER THE N 1/2 OF THE AREA AND NEAR TO BELOW NORMAL POPS
ARE EXPECTED IN THE S 1/2. SOME UPPER RIDGING IS EXPECTED OVER THE
WEEKEND AHEAD OF ANOTHER SHORTWAVE WHICH WILL MOVE SE INTO THE AREA
EARLY NEXT WEEK.
&&
.AVIATION...VFR CONDITIONS ARE EXPECTED TO PERSIST THROUGH AT LEAST
TOMORROW. VISIBLE SATELLITE AND RUC ANALYSIS CLEARLY SHOW WEAK
TROUGH APPROACHING THE NEARSHORE WATERS OFF OF CRESCENT CITY. MAINLY
LIMITED LOW TO MID-LEVEL MOISTURE WITH VERY WEAK FORCING FOR LIFT
WILL LIMIT CIGS TO BKN/OVC 3-5KFT AT WORST AT KCEC AND PERHAPS AS
FAR SOUTH AS KACV TONIGHT. THESE WILL LIKELY CLEAR BY 12Z GIVING WAY
TO SOME LEFTOVER MID OR HIGH CLOUDS. WINDS WILL BECOME LIGHT AFTER
SUNSET TONIGHT AND PICK UP AGAIN AT THE COAST TOMORROW OUT OF THE
NORTHWEST BUT MOST GUSTS WILL BE UNDER 20KT EVEN IN THE AFTERNOON.
THERE IS A LOW CHC OF A SHOWER AT KCEC BUT NO SIGNIFICANT REDUCTION
TO VISIBILITY IS EXPECTED AT ANY OF THE TAF SITES.
&&
.MARINE...EXTENDED SMALL CRAFT THROUGH SUNDAY MORNING AS A MORE
SIGNIFICANT WAVE TRAIN IS PROJECTED TO ARRIVE SATURDAY MORNING AND
PERSIST THROUGH THAT TIME. GENERALLY LOOKING AT 14-17 FT AT AROUND
15 SECONDS. SOME OF THE FORERUNNERS FRIDAY NIGHT MAY BE 17-19 SECS
BUT UNDER 3 FEET. OTHERWISE CURRENTLY WE HAVE 10-12 FT SEAS AT 11
SECONDS AND THESE WILL PERSIST THROUGH THURSDAY...BEFORE BUILDING TO
12-14 FT AT 15 SECONDS AS ANOTHER WAVE SYSTEM ARRIVES THURSDAY NIGHT
INTO FRIDAY. WINDS WILL GENERALLY PERSIST OUT OF THE NORTH AT 10 TO
20 KT...HIGHER ACROSS THE OUTER WATERS SOUTH OF THE CAPE WITH SOME
GUSTS TO GALE FORCE POSSIBLE THE NEXT FEW AFTERNOONS. ONE TROUGH
PASSING THROUGH TONIGHT AND ANOTHER THURSDAY NIGHT WILL TEMPORARILY
WEAKEN THESE WINDS. THIS WILL ESPECIALLY BE TRUE NORTH OF THE CAPE
WHERE THEY WILL EVEN BACK TO THE WEST OR SOUTHWEST FOR A SHORT TIME
AHEAD OF THESE TROUGHS. ANOTHER MORE SIGNIFICANT LONG PERIOD WAVE
SYSTEM IS POSSIBLE NEXT MONDAY.
&&
.EKA WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...SMALL CRAFT ADVISORY ALL
WATERS.
&&
$$
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AREA FORECAST DISCUSSION
NWS SACRAMENTO CA
947 AM PST TUE FEB 19 2013
.SHORT TERM DISCUSSION...
UPPER IMPULSE THAT WAS OVER 50N/135W YESTERDAY HAS DROPPED SWD TO
JUST NEAR THE SFO BAY AREA AS OF MID MORNING. SURFACE FRONT HAS ALSO
PUSHED INLAND WITH THE UP VALLEY PRESSURE GRADIENTS INCREASING TO
ALMOST 6 MBS FROM RDD TO SAC. WE DID A QUICK MORNING UPDATE TO
INCREASE THE WIND SPEEDS UNTIL FROPA THIS AFTERNOON. THE WINDS IN
THE N END OF THE VALLEY SHOULD DECREASE THIS AFTERNOON WHILE THERE
SHOULD BE WINDS PICKING UP THROUGH THE DELTA AND SRN SAC VLY.
PREFRONTAL PRECIP MAKING ITS WAY ACROSS THE VALLEY AND INTO THE
SIERNEV...DELTA AREA...AND SAC AREA AT PRESS TIME...IS FORECAST BY
THE RUC TO BECOME N-S ORIENTED OVER THE SIERNEV BY LATE AFTERNOON
AND INTO EVENING. SO SNOWFALL IS EXPECTED TO PICK UP OVER THE
SIERNEV...AND CONTINUE INTO EVENING...BEFORE BEGINNING TO DECREASE
AFTER 03Z-04Z OR SO. PRECIP WILL THEN TAPER OFF AND TURN SHOWERY
OVER THE VALLEY AND COASTAL RANGE BEHIND THE PREFRONTAL BAND. GIVEN
THIS TIMING...THE ADVISORY FOR THE SIERNEV LOOKS GOOD...WITH THE
ADVISORY FOR THE SHASTA AND COASTAL RANGE POSSIBLY EXPIRING WITH THE
AFTERNOON PACKAGE. SNOW PROFILERS AND SPOTTER REPORTS INDICATE THE
SNOW LEVEL IS ABOUT 2000 TO 2500 FT...WITH A FEW REPORTS DOWN TO
1500 FEET OVER THE COASTAL RANGE AS THE COLD MID LEVEL IMPULSE DROPS
SWD.
THE UPPER IMPULSE IS PROGGED TO DIG INTO THE BASE OF THE TROF OVER
THE WRN STATES WITH THE COLD POCKET MAINLY TRACKING ACROSS THE
COASTAL RANGE. CAN`T RULE OUT A THUNDERSTORM OR TWO...BUT LOOKING AT
THE BUFKIT FORECAST SOUNDINGS AND RAOB RECONSTRUCTION...WE NEED TO
WARM INTO THE LOW TO MID 50S TO GET SUFFICIENT CAPE OF A FEW HUNDRED
J/KG IN THE VALLEY...AND THE AIR MASS WILL BE COOLING TOO RAPIDLY
BEHIND THE FRONT. DURING THE AFTERNOON...THE SHEAR VALUES ALSO
LOOK TOO LOW FOR SEVERE WX. MANY OF THE SHOWERS THOUGH ARE LIKELY
TO CONTAIN SMALL HAIL/GRAUPEL.
MOISTURE IS LIMITED WITH THIS SYSTEM WITH VERY LOW PWS OF .40 TO .50
INCHES SO THE SHOWERS ARE QUITE SCATTERED UNDER THE IMPULSE AND
SHOULD REMAIN THAT WAY TODAY. BEST CLOUD ENHANCEMENT IS OVER THE
NERN QUARTER OF THE FORECAST AREA IN THE DIFFLUENT UPPER FLOW FROM
THE LOW. THIS IS LIKELY TO SHIFT SWD AND HIT THE 80/50 CORRIDOR AND
AREAS SWD THIS AFTERNOON AND EARLY EVENING. GIVEN THE UPPER
DIFFLUENCE OF THE 500 MBS FLOW AND OROGRAPHICS...ALBEIT FOR A
LIMITED TIME...THE HEAIEST QPF WILL BE OVER THE W SLOPE SIERNEV
WHERE WIDESPREAD QPFS OF .50 INCHES...LOCAL AMOUNTS UP TO AROUND .90
INCHES...AND ISOLATED 1.0 INCHES ARE FORECAST. 6 TO 10 INHCES OF
SNOW STILL LOOKS GOOD FOR THE SIERNEV. JHM
.PREVIOUS DISCUSSION...
SATIMG SHOWS DEEP TROUGH DIGGING SOUTHWARD TOWARD NORCAL EARLY
THIS MORNING WITH LOTS OF COLD-AIR CUMULUS AROUND THE LOW CENTER
OFFSHORE OREGON. BLENDED PW PRODUCT INDICATES LIMITED MOISTURE
WITH THE SYSTEM WITH PW OF ONLY 0.40 TO 0.50 INCHES. SCATTERED
LIGHT SNOW SHOWERS DEVELOPED DURING THE OVERNIGHT HOURS ACROSS THE
NORTHERN SIERRA AS THE UPPER FRONT AND ITS ASSOCIATED MID/UPPER
LEVEL JET PROVIDED ENOUGH LIFT...BUT ELSEWHERE SKIES HAVE BEEN
PARTLY CLOUDY WITH SOUTHERLY BREEZES PICKING UP IN THE SACRAMENTO
VALLEY.
TIMING STILL LOOKS GOOD FOR THE MAIN FRONTAL BAND OF SHOWERS TO
MOVE INLAND ACROSS NORCAL AROUND MIDDAY. RADAR SHOWS THE BAND
MOVING ONSHORE NW CA ATTM. THE STRONG DYNAMICS AND STRONG CAA
WILL LEAD TO SOME DECENT QPF WITH HIGHER THAN NORMAL SNOW-LIQUID
RATIOS. STEEPENING LAPSE RATES WILL LEAD TO CONVECTIVE ENHANCEMENT
OF SNOWFALL OVER THE REGION INTO THIS EVENING. LATEST HI-RES NAM
CROSS-SECTIONS INDICATE SNOWFALL WILL INCREASE ALONG I-80 OVER THE
NORTHERN SIERRA THIS MORNING AND CONTINUE INTO THIS EVENING.
SNOWFALL TOTALS OF 10 TO 12 INCHES WITH LOCALLY HIGHER AMOUNTS
WILL BE POSSIBLE ABOVE ABOUT 4000 FEET WITH LIGHTER ACCUMULATIONS
EXTENDING DOWN INTO THE FOOTHILL ELEVATIONS.
POTENTIAL FOR THUNDERSTORMS IS GOOD WITH THE UPPER LOW MOVING
THROUGH THIS AFTERNOON. 500 MB TEMPS FORECAST TO BE VERY COLD...
-30C TO -35C AS THE LOW MOVES OVERHEAD AROUND 00Z WED. LACK OF
SUSTAINED SURFACE HEATING DUE TO CLOUD COVER AND WEAK SHEAR
PARAMETERS DUE TO THE LIGHTER WINDS NEAR THE UPPER LOW CENTER WILL
LIMIT SEVERE POTENTIAL TODAY. HOWEVER...IT DOES LOOK LIKE LOW-
TOPPED STORMS THAT DEVELOP WILL BE ACCOMPANIED BY COPIOUS AMOUNTS
OF SMALL HAIL.
SYSTEM DROPS QUICKLY SOUTH OF THE REGION TONIGHT WITH SHOWERS
EXPECTED TO TAPER OFF FROM THE NORTH DURING THE EVENING. SHORT-
WAVE RIDGING WEDNESDAY IS EXPECTED TO PROVIDE A MOSTLY DRY DAY FOR
NORCAL THOUGH A FEW SHOWERS WILL BE POSSIBLE ACROSS THE HIGHER
TERRAIN. ANOTHER IMPULSE (WEAKER) IS FORECAST TO DROP SOUTHWARD
ALONG THE COAST WEDNESDAY NIGHT...THOUGH THERE IS MORE UNCERTAINTY
WITH THE TRACK OF THIS FEATURE...BRINGING WITH IT A CHANCE OF
SHOWERS. RIDGING OVER THE AREA THURSDAY AND FRIDAY ARE EXPECTED TO
LEAVE MOST OF THE AREA DRY...THOUGH MOISTURE SPILLING OVER THE
RIDGE MAY BRING SOME SHOWERS TO THE NORTHERN MOUNTAINS.
.EXTENDED DISCUSSION (SATURDAY THROUGH TUESDAY)
EXTENDED MODELS STILL STRUGGLE TO CAPTURE DETAILS OF THE UNSETTLED
WEATHER PATTERN IN THE EXTENDED FORECAST. ANOTHER TROUGH SYSTEM
WILL DROP INTO THE PACIFIC NORTHWEST FRIDAY NIGHT INTO SATURDAY
AND THE BASE OF THE TROUGH WILL IMPACT NORCAL. THE ECMWF MODEL
SUGGESTS A DEEPER TROUGH EXTENDING TOWARDS SOCAL WHILE THE GFS AND
GEM SHOW THE BASE OF THE TROUGH BRUSHING NORCAL THEN DEEPENING
DEEPENING OVER THE GREAT BASIN. DRIER FOR MOST OF OUR CWA BY SUNDAY
AFTERNOON THOUGH LINGERING SHOWERS ARE POSSIBLE ACROSS FAR NORCAL
AND HIGHER TERRAIN. MODELS SUGGEST ANOTHER SYSTEM IMPACTING NORCAL
EITHER ON MONDAY OR TUESDAY. AGAIN MODEL CONSISTENCY HAS BEEN POOR
SO HAVE JUST KEPT SLIGHT CHANCE OF RAIN/SNOW DURING THIS TIME FRAME.
TEMPERATURES IN THE EXTENDED WILL GENERALLY BE NEAR TO SLIGHTLY
BELOW NORMAL FOR DAYTIME HIGHS: MID 50S TO LOW 60S IN THE VALLEY AND
30S TO 40S IN THE MOUNTAINS. MINIMUM TEMPERATURES ARE EXPECTED TO BE
BELOW NORMAL WITH LOWS IN THE MID 30S TO LOW 40S IN THE VALLEY AND
TEENS TO 20S IN THE MOUNTAINS.
&&
.AVIATION...
INCOMING WEATHER SYSTEM IS NOW BRINGING VCSH TO NORCAL VALLEYS AND
SNOW TO THE MOUNTAINS. -RA WITH MVFR CIGS AND BREEZY SOUTHERLY
WINDS GUSTING UP TO 30KTS CURRENTLY IMPACTING KRDD-KRBL VICINITY
WILL SPREAD SOUTHWARD THIS MORNING REACHING THE SAC METRO AREA BY
MID-MORNING AND THE KSCK-KMOD VCNTY AFTER 18Z. VALLEY
THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON AND EVENING WHICH COULD
BRING LOCALIZED STRONG GUSTS, HEAVIER RAIN AND SMALL HAIL.
GENERALLY SOUTH TO SOUTHWEST FLOW TODAY BECOMING NORTHERLY TONIGHT
WITH IMPROVING CIGS AND DRIER WEATHER AFTER THE STORM SYSTEM
PASSES. CURRENT SNOW LEVELS AROUND 2500-3500 FT AND WILL CONTINUE
TO LOWER THROUGH TOMORROW TO AROUND 1500 FT. IFR/LIFR CONDITIONS
EXPECTED TODAY IN THE MOUNTAINS WITH SN AND WIND GUSTS UP TO 30
KTS. -DVC
&&
.STO WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 11 PM PST THIS EVENING ABOVE 2000
FEET FOR THE MOTHERLODE...NORTHEAST FOOTHILLS/SACRAMENTO
VALLEY...WEST SLOPE NORTHERN SIERRA NEVADA...WESTERN PLUMAS
COUNTY/LASSEN PARK.
WINTER WEATHER ADVISORY UNTIL 6 PM PST THIS EVENING ABOVE 2000
FEET FOR THE CLEAR LAKE/SOUTHERN LAKE COUNTY...MOUNTAINS
SOUTHWESTERN SHASTA COUNTY TO NORTHERN LAKE COUNTY...SHASTA LAKE
AREA / NORTHERN SHASTA COUNTY.
&&
$$
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
838 PM MST WED FEB 20 2013
.UPDATE...
ISSUED AT 838 PM MST WED FEB 20 2013
LATEST SATELLITE AND RADAR TRENDS CONTINUE TO SHOW AREA OF
MODERATE TO HEAVY SNOWFALL WORKING SLOWLY WEST ACROSS THE WEST
ELKS AND INTO THE GRAND MESA. SO CURRENT HIGHLIGHTS THROUGH THIS
CORRIDOR REMAIN ON TRACK. TO THE SOUTH AND WEST...ACTIVITY
CONTINUES TO DIMINISH...WITH CLEARING SKIES AND PATCHY FOG
DEVELOPING. ALSO APPEARS THAT THE SOUTHERN LOW WILL NOT BECOME A
MAJOR PLAYER ACROSS OUR SOUTHERN ZONES AS IT SLOWLY PUSHES ACROSS
NEW MEXICO BEFORE LIFTING NORTHEAST INTO THE PLAINS.
THEREFORE...WENT AHEAD AND DROPPED THE HIGHLIGHTS ACROSS EASTERN
UTAH AND THE SOUTHERN VALLEYS AS POTENTIAL FOR SIGNIFICANT
SNOWFALL HAS DIMINISHED.
UPDATE ISSUED AT 546 PM MST WED FEB 20 2013
LATEST SHORT TERM MODEL GUIDANCE INDICATING TIGHT AREA OF
CONVERGENCE WILL BE DEVELOPING ACROSS THE EAST CENTRAL SECTIONS OF
THE FORECAST AREA OVER THE NEXT FEW HOURS. SPOTTER REPORTS
INDICATE AREAS OF HEAVY SNOW NOW FALLING IN THE VICINITY OF
GUNNISON...MONTROSE AND DELTA WITH TWO INCHES ALREADY IN THE
GUNNISON AREA. HAVE HOISTED A WINTER WEATHER ADVISORY FOR COLORADO
ZONE 11...WHICH INCLUDES MONTROSE AND DELTA AND BOOSTED SNOWFALL
AMOUNTS INTO THE 3 TO 6 RANGE BY MIDDAY THURSDAY. HAVE ALSO NUDGE
ACCUMULATIONS UP ACROSS THE WEST ELKS AND CRESTED BUTTE AREA WHICH
SHOULD BENEFIT NICELY AS THIS LOW LEVEL CONVERGENCE SETS UP.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 230 PM MST WED FEB 20 2013
GOOD MODEL AGREEMENT WITH SMALL AND LARGE SCALE FEATURES ADDING TO
FORECAST CONFIDENCE. THE MAIN UPPER LOW TRACKING THROUGH SOUTHERN
ARIZONA THIS AFTERNOON MOVES SOUTHERN NEW MEXICO TONIGHT AND INTO
KANSAS ON THURSDAY. A SECOND CENTER TO THE LOW TRACKS THROUGH
NORTHERN NEW MEXICO THIS EVENING. CURRENTLY SATELLITE SHOWS THREE
ENHANCED W-E ORIENTED BANDS OF ENHANCED CLOUDS OFF THE NE SIDE OF
THE LOW. THE SECOND BAND IS OVER SE UT-SW CO PRODUCING WIDESPREAD
SNOW. THE THIRD BAND IS OVER THE NORTHERN CWA AND APPARENTLY LACKS
SUFFICIENT LOW-MID LEVEL MOISTURE OR FORCING TO PRODUCE SNOW. JET
SUPPORT REMAINS WELL SOUTH OF THE FORECAST AREA AND SYNOPTIC
FORCING SPREADS ACROSS THE REGION THIS AFTERNOON AND EVENING BUT
IS STRONGEST SOUTH.
THIS AFTERNOON BEST SNOW ACCUMULATIONS HAVE OCCURRED IN PAGOSA
TOWARDS WOLF CREEK PASS WHERE THE FORCING...MOISTURE...AND
MARGINAL INSTABILITY ALL BULLS EYE. MAINLY SOUTH OROGRAPHIC
SNOWFALL CONTINUES ELSEWHERE FAVORING THE SOUTH-FACING SLOPES.
THIS EVENING THE 18Z RAP AND NAM INDICATE ENHANCED SNOWFALL UNDER
A MID LEVEL CIRCULATION OVER THE WEST ELK MOUNTAINS SOUTHWARD INTO
THE HIGHWAY 50 CORRIDOR THROUGH THE GUNNISON BASIN. THE LOW LEVEL
CONVERGENCE SHIFTS EAST OF THE FORECAST AREA AFTER MIDNIGHT WITH
SNOW ACCUMULATION SHIFTING TO NW-FACING SLOPES INCLUDING THE SKI
AREAS. THIS WILL FAVOR THE CENTRAL MOUNTAINS INTO THURSDAY.
AREAS OF LESS CERTAINTY INCLUDE THE MOUNTAINS OF EASTERN UTAH
WHERE MODELS STRUGGLE TO PRODUCE ADVISORY LEVEL SNOW ACCUMULATION.
MONTROSE MAY GET UP TO 4 INCHES OF SNOWFALL AS THE FLOW TURNS TO
NW/UPVALLEY. CORTEZ HAS BEEN JUST ABOVE FREEZING THIS AFTERNOON
BUT EXPECT THE FOOTHILLS FROM MANCOS TO DOVE CREEK TO SEE
ACCUMULATIONS CONTINUING THIS EVENING.
IN NW FLOW LIGHT SNOWFALL CONTINUES OVER THE COLORADO SPINE
THROUGH THURSDAY BUT DIMINISHES THURSDAY NIGHT. ALL HIGHLIGHTS END
THURSDAY AFTERNOON AND THIS STILL SEEMS REASONABLE EVEN WITH SNOW
CONTINUING AS ACCUMULATIONS ARE PROGGED TO BE VERY LIGHT.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 230 PM MST WED FEB 20 2013
A RATHER ILL-DEFINED SECONDARY UPPER TROUGH DROPS SOUTHEAST ACROSS
THE FORECAST AREA FRI BUT IS BOLSTERED BY A TRAILING JET MAX THAT
QUICKLY CATCHES IT FRI AFTERNOON. MOISTURE CONTENT DECREASES AND
LAPSE RATES BECOME MORE STABLE...BUT OROGRAPHICS IN THE PERSISTENT
NW FLOW AND WEAK DYNAMICS WITH THE TROUGH SHOULD PROVIDE ENOUGH
LIFT TO KEEP LIGHT SNOW OVER PARTS OF THE NRN MTNS FRIDAY FOR 1-3
INCHES OF NEW SNOW IN PLACES. HAVE BUMPED POPS UP A BIT FRI AS A
RESULT.
TRANSIENT SHORTWAVE RIDGING AND STABLE WARM ADVECTION ALOFT WILL
PROVIDE A LULL IN THE ACTIVITY FRIDAY NIGHT AS THE NEXT PACIFIC
STORM PUSHES INTO WA/OR. THIS STORM LOOKS TO BRING AN ENERGETIC
COLD FRONT INTO NE UT ABOUT MIDDAY SATURDAY AND THEN SOUTHEAST
ACROSS WRN CO SAT AFTERNOON/EVENING. CONFIDENCE IS HIGH AS MODELS
HAVE BEEN CONSISTENT WITH EACH OTHER AND FROM RUN TO RUN. WHILE
MOISTURE CONTENT DECREASES AS THE STORM CROSSES THE INTERIOR
WEST...STRONG FRONTOGENETIC AND DYNAMIC FORCING WITH UNSTABLE
700-500 MB LAPSE RATES COULD STILL LEAD TO A BURST OF MODERATE TO
PERHAPS HEAVY SNOW WITH THE FRONT...WHICH MAY BE COMPOUNDED BY WINDY
CONDITIONS AND BLOWING SNOW OVER THE HIGHER TERRAIN. COLD ADVECTION
IN N TO NW FLOW BEHIND THE FRONT SHOULD KEEP SNOW OVER THE MTNS SAT
NIGHT. WINTER HIGHLIGHTS MAY BE NEEDED FOR THIS STORM. A CHANCE OF
SNOW WILL CONTINUE SUNDAY WITH THE NORTHERN MTNS FAVORED IN NW FLOW.
AFTER ANOTHER LULL ON MONDAY...THE NEXT PACIFIC STORM SHOULD REACH
OUR AREA ABOUT TUE EVENING.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 838 PM MST WED FEB 20 2013
WIDESPREAD SNOW SHOWERS WILL CONTINUE TO HAMPER CENTRAL VALLEY
TERMINALS...INCLUDING KASE...KEGE...KGUC...KMTJ AND KRIL THROUGH
18Z. THIS WILL RESULT IN AREAS OF IFR AND LIFR CONDS WITH CIGS AND
VSBYS GREATLY REDUCED AS SNOW SHOWERS MOVE THROUGH. REMAINING
AREAS WILL CONTINUE TO SEE VFR...WITH OCCASIONAL MVFR CONDS AS
SCATTERED SNOW SHOWERS MOVE THROUGH. CONDITIONS IMPROVE FROM
SOUTHWEST TO NORTHEAST THURSDAY AFTERNOON AND EVENING AS THE STORM
SYSTEM RESPONSIBLE FOR THE SNOW LIFTS OUT INTO THE PLAINS.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...WINTER WEATHER ADVISORY UNTIL 6 PM MST THURSDAY FOR COZ003-
007>010-012-013-017>019.
WINTER WEATHER ADVISORY UNTIL NOON MST THURSDAY FOR COZ011-014.
UT...NONE.
&&
$$
UPDATE...JDC
SHORT TERM...JOE
LONG TERM...JAD
AVIATION...JDC
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
547 PM MST WED FEB 20 2013
.UPDATE...
ISSUED AT 546 PM MST WED FEB 20 2013
LATEST SHORT TERM MODEL GUIDANCE INDICATING TIGHT AREA OF
CONVERGENCE WILL BE DEVELOPING ACROSS THE EAST CENTRAL SECTIONS OF
THE FORECAST AREA OVER THE NEXT FEW HOURS. SPOTTER REPORTS
INDICATE AREAS OF HEAVY SNOW NOW FALLING IN THE VICINITY OF
GUNNISON...MONTROSE AND DELTA WITH TWO INCHES ALREADY IN THE
GUNNISON AREA. HAVE HOISTED A WINTER WEATHER ADVISORY FOR COLORADO
ZONE 11...WHICH INCLUDES MONTROSE AND DELTA AND BOOSTED SNOWFALL
AMOUNTS INTO THE 3 TO 6 RANGE BY MIDDAY THURSDAY. HAVE ALSO NUDGE
ACCUMULATIONS UP ACROSS THE WEST ELKS AND CRESTED BUTTE AREA WHICH
SHOULD BENEFIT NICELY AS THIS LOW LEVEL CONVERGENCE SETS UP.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 230 PM MST WED FEB 20 2013
GOOD MODEL AGREEMENT WITH SMALL AND LARGE SCALE FEATURES ADDING TO
FORECAST CONFIDENCE. THE MAIN UPPER LOW TRACKING THROUGH SOUTHERN
ARIZONA THIS AFTERNOON MOVES SOUTHERN NEW MEXICO TONIGHT AND INTO
KANSAS ON THURSDAY. A SECOND CENTER TO THE LOW TRACKS THROUGH
NORTHERN NEW MEXICO THIS EVENING. CURRENTLY SATELLITE SHOWS THREE
ENHANCED W-E ORIENTED BANDS OF ENHANCED CLOUDS OFF THE NE SIDE OF
THE LOW. THE SECOND BAND IS OVER SE UT-SW CO PRODUCING WIDESPREAD
SNOW. THE THIRD BAND IS OVER THE NORTHERN CWA AND APPARENTLY LACKS
SUFFICIENT LOW-MID LEVEL MOISTURE OR FORCING TO PRODUCE SNOW. JET
SUPPORT REMAINS WELL SOUTH OF THE FORECAST AREA AND SYNOPTIC
FORCING SPREADS ACROSS THE REGION THIS AFTERNOON AND EVENING BUT
IS STRONGEST SOUTH.
THIS AFTERNOON BEST SNOW ACCUMULATIONS HAVE OCCURRED IN PAGOSA
TOWARDS WOLF CREEK PASS WHERE THE FORCING...MOISTURE...AND
MARGINAL INSTABILITY ALL BULLSEYE. MAINLY SOUTH OROGRAPHIC
SNOWFALL CONTINUES ELSEWHERE FAVORING THE SOUTH-FACING SLOPES.
THIS EVENING THE 18Z RAP AND NAM INDICATE ENHANCED SNOWFALL UNDER
A MID LEVEL CIRCULATION OVER THE WEST ELK MOUNTAINS SOUTHWARD INTO
THE HIGHWAY 50 CORRIDOR THROUGH THE GUNNISON BASIN. THE LOW LEVEL
CONVERGENCE SHIFTS EAST OF THE FORECAST AREA AFTER MIDNIGHT WITH
SNOW ACCUMULATION SHIFTING TO NW-FACING SLOPES INCLUDING THE SKI
AREAS. THIS WILL FAVOR THE CENTRAL MOUNTAINS INTO THURSDAY.
AREAS OF LESS CERTAINTY INCLUDE THE MOUNTAINS OF EASTERN UTAH
WHERE MODELS STRUGGLE TO PRODUCE ADVISORY LEVEL SNOW ACCUMULATION.
MONTROSE MAY GET UP TO 4 INCHES OF SNOWFALL AS THE FLOW TURNS TO
NW/UPVALLEY. CORTEZ HAS BEEN JUST ABOVE FREEZING THIS AFTERNOON
BUT EXPECT THE FOOTHILLS FROM MANCOS TO DOVE CREEK TO SEE
ACCUMULATIONS CONTINUING THIS EVENING.
IN NW FLOW LIGHT SNOWFALL CONTINUES OVER THE COLORADO SPINE
THROUGH THURSDAY BUT DIMINISHES THURSDAY NIGHT. ALL HIGHLIGHTS END
THURSDAY AFTERNOON AND THIS STILL SEEMS REASONABLE EVEN WITH SNOW
CONTINUING AS ACCUMULATIONS ARE PROGGED TO BE VERY LIGHT.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 230 PM MST WED FEB 20 2013
A RATHER ILL-DEFINED SECONDARY UPPER TROUGH DROPS SOUTHEAST ACROSS
THE FORECAST AREA FRI BUT IS BOLSTERED BY A TRAILING JET MAX THAT
QUICKLY CATCHES IT FRI AFTERNOON. MOISTURE CONTENT DECREASES AND
LAPSE RATES BECOME MORE STABLE...BUT OROGRAPHICS IN THE PERSISTENT
NW FLOW AND WEAK DYNAMICS WITH THE TROUGH SHOULD PROVIDE ENOUGH
LIFT TO KEEP LIGHT SNOW OVER PARTS OF THE NRN MTNS FRIDAY FOR 1-3
INCHES OF NEW SNOW IN PLACES. HAVE BUMPED POPS UP A BIT FRI AS A
RESULT.
TRANSIENT SHORTWAVE RIDGING AND STABLE WARM ADVECTION ALOFT WILL
PROVIDE A LULL IN THE ACTIVITY FRIDAY NIGHT AS THE NEXT PACIFIC
STORM PUSHES INTO WA/OR. THIS STORM LOOKS TO BRING AN ENERGETIC
COLD FRONT INTO NE UT ABOUT MIDDAY SATURDAY AND THEN SOUTHEAST
ACROSS WRN CO SAT AFTERNOON/EVENING. CONFIDENCE IS HIGH AS MODELS
HAVE BEEN CONSISTENT WITH EACH OTHER AND FROM RUN TO RUN. WHILE
MOISTURE CONTENT DECREASES AS THE STORM CROSSES THE INTERIOR
WEST...STRONG FRONTOGENETIC AND DYNAMIC FORCING WITH UNSTABLE
700-500 MB LAPSE RATES COULD STILL LEAD TO A BURST OF MODERATE TO
PERHAPS HEAVY SNOW WITH THE FRONT...WHICH MAY BE COMPOUNDED BY WINDY
CONDITIONS AND BLOWING SNOW OVER THE HIGHER TERRAIN. COLD ADVECTION
IN N TO NW FLOW BEHIND THE FRONT SHOULD KEEP SNOW OVER THE MTNS SAT
NIGHT. WINTER HIGHLIGHTS MAY BE NEEDED FOR THIS STORM. A CHANCE OF
SNOW WILL CONTINUE SUNDAY WITH THE NORTHERN MTNS FAVORED IN NW FLOW.
AFTER ANOTHER LULL ON MONDAY...THE NEXT PACIFIC STORM SHOULD REACH
OUR AREA ABOUT TUE EVENING.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY AFTERNOON)
ISSUED AT 230 PM MST WED FEB 20 2013
IFR/VIFR CONDITIONS REPORTED OVER KCEZ KDRO KPSO THAT WILL
CONTINUE THROUGH TONIGHT IN WIDESPREAD SNOW SHOWERS. VFR
CONDITIONS IN THE CENTRAL VALLEYS WILL DETERIORATE THIS EVENING AS
SNOW SPREADS NORTHWARD. MOUNTAIN OBSCURATIONS WILL BE WIDESPREAD
ALONG AND SOUTH OF I-70 THROUGH THURSDAY. LOWERED FLIGHT CRITERIA
IN THE MVFR TO IFR RANGE CAN BE EXPECTED AT THE KRIL...KMTJ...KASE
AND KEGE TERMINALS WITH SNOW AND LOW CIGS LIKELY. THE KVEL AND
KGJT TERMINALS WILL BE ON THE EDGE AND OF THE HEAVIER
PRECIPITATION AND VFR CONDITIONS ARE FORECAST TO PREVAIL...THOUGH
SHOWERS IN THE VICINITY OF THESE TERMINALS CAN BE EXPECTED. THE
SOUTHERN AIRPORTS WILL SEE IMPROVING CONDITIONS THROUGH THURSDAY
AFTERNOON.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...WINTER WEATHER ADVISORY UNTIL NOON MST THURSDAY FOR COZ011-014.
WINTER WEATHER ADVISORY UNTIL 6 PM MST THURSDAY FOR COZ003-
007>010-012-013-017>019.
WINTER WEATHER ADVISORY UNTIL 3 AM MST THURSDAY FOR COZ021-022.
WINTER STORM WARNING UNTIL 9 AM MST THURSDAY FOR COZ023.
UT...WINTER WEATHER ADVISORY UNTIL NOON MST THURSDAY FOR UTZ025-028.
&&
$$
UPDATE...JDC
SHORT TERM...JOE
LONG TERM...JAD
AVIATION...JOE
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
923 AM EST TUE FEB 19 2013
.SYNOPSIS...
LOW PRESSURE WILL TRACK FROM THE GREAT LAKES REGION TODAY, THEN
ACROSS SOUTHEASTERN CANADA TO NORTHERN NEW ENGLAND TONIGHT AND
WEDNESDAY. AN ASSOCIATED COLD FRONT WILL SLIDE ACROSS OUR AREA
THIS EVENING. HIGH PRESSURE FROM CENTRAL CANADA WILL THEN BUILD
SOUTH AND EASTWARD THURSDAY. THIS HIGH WILL BE SHIFTING EAST LATE
THURSDAY INTO FRIDAY, AS ANOTHER LOW PRESSURE SYSTEM MOVES INTO THE
GREAT LAKES AND OHIO VALLEY FRIDAY NIGHT INTO SATURDAY. LOW PRESSURE
FARTHER SOUTH ON THE COLD FRONT THEN EXITS THE MID ATLANTIC COAST
SATURDAY NIGHT INTO SUNDAY. HIGH PRESSURE THEN ARRIVES LATE SUNDAY
INTO MONDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
BASED ON LATEST RADAR TRENDS, HAVE SLOWED DOWN THE ONSET OF PRECIP
TODAY AS IT IS HAVING A HARD TIME PROGRESSING EWD THIS MORNING.
THIS LATER ARRIVAL SHOULD FURTHER MITIGATE ANY WINTRY PRECIP CHCS
EXCEPT FOR THE FAR N AND W. LLJ KICKED IN AND HAS ALREADY WARMED
SOME LOCATIONS QUITE NICELY. KRDG WENT FROM 27 DEGREES TO 40
DEGREES IN ONE HOUR, YET OTHER LOCATIONS STILL REMAIN BELOW
FREEZING. SO, FOR THIS UPDATE, HAVE LOWERED POPS FOR THE NEXT FEW
HOURS ACRS THE BOARD, AND TRIED TO CAPTURE PTYPE TRENDS AS BEST AS
PSBL, REALIZING THE LARGE SWINGS IN TEMPS WILL BE DIFFICULT TO
FCST IN SOME LOCATIONS. ALSO TWEAKED BACK WINDS IN SOME AREAS FOR
THE NEXT FEW HOURS BASED ON CURRENT TRENDS.
THE GFS INITIALIZATION LOOKED SLIGHTLY BETTER THAN THE WRF-NMMB AND
THE FORECAST PACKAGE WAS LEANED ABOUT THREE QUARTERS TOWARD ITS
TIMING. WE DID OPT FOR THE WRF-NMMB SFC THERMAL FIELDS OVER THE GFS
IN THE POCONOS.
THE OVERALL FORCING STILL LOOKS SPLIT. THE FCST ISENTROPIC LIFT IS
NOT ROBUST, THE MID LEVEL QVEC CONVERGENCE AND FGEN FORCING WEAKEN
AS IT MOVES ACROSS THE APPALACHIANS. THE LOW LEVEL THETA E RIDGE IS
NOT ANYTHING TO WRITE HOME FOR (PLENTY OF LOW SFC DEW POINTS INTO
GEORGIA). THE BEST "CONVECTIVE" CONTRIBUTION GOES NORTHWEST OF CWA.
WHAT IT STILL DOES HAVE GOING FOR IT IS THE EXIT REGION OF THE 250MB
JET. WE SAW WHAT THAT DID FOR THE SYSTEM LAST FRIDAY NIGHT AND WE
ARE COUNTING ON IT TO SAVE THE QPF DAY.
SENSIBLE WEATHER, WE START BRINGING IN THE POPS AT 14Z, CLOSER TO
THE GFS TIMING. THERE IS PLENTY OF DRY AIR FOR THIS MOISTURE TO
OVERCOME, SO WE BELIEVE IT WILL TAKE A COUPLE OF HOURS FOR PCPN TO
GET GOING (EARLY TO MID AFTERNOON). THIS ALSO COINCIDES BETTER WITH
THE JET. THE THETA E RIDGE GETS OFFSHORE PRETTY FAST AND THE FCST
MID LVL WAA IS WAY EAST BY 00Z, SO POPS WERE DROPPED LATE IN THE
AFTERNOON IN THE WEST.
FOR PTYPE, THE DRY AIR MASS IN PLACE WILL MAKE IT EASY TO EVAPORATE
COOL TO SNOW. THE QUESTION IS HOW DEEP WILL THE THERMAL SOUNDING
HAVE TO BE COOLED FOR SNOW. THE LATEST ACAR SOUNDING FROM PHL
ALREADY HAS THE FREEZING LEVEL ABOVE 6K. SO THE "MENTION" OF SNOW
WAS LIMITED TO THE PHL FAR NWRN SUBURBS, RARITAN BASIN IN NJ AND
POINTS NW. THE LATER ARRIVAL TIME AND LIKELY LIGHT INTENSITY
START HAS PRETTY MUCH REMOVED THE RISK FOR FREEZING RAIN.
THE ONLY LOCALE THAT SHOULD HANG ON TO SNOW ARE THE POCONOS WHERE
THE WRF/HI RES ARW/ AND HRRR ALL DROP SFC TEMPS TO FREEZING AND
LEVEL THEM THERE. LATE IN THE DAY SOME SOUNDINGS SUGGEST WE LOSE THE
ICE AND WITH LESSER INTENSITY AND A CONTINUING SOUTH WIND, THE SNOW
COULD MIX OR CHANGE TO RAIN EVEN THERE. AS MENTIONED ABOVE THE MID
LEVEL FGEN FORCING WEAKENS AND THE BEST FGEN FRCG THAT MAKES IT
ACROSS THE MOUNTAINS REMAINS TOWARD THE 500MB LEVEL, COMES AS NO
SURPRISE THAT THE BEST OMEGA IS FCST TO ABOVE THE SNOW GROWTH AREA.
THIS COMBINED WITH MODEL QPFS OF AROUND A QUARTER OF AN INCH SUGGEST
AN INCH OR TWO OF SNOW AS THE MOST LIKELY OUTCOME FOR THE HIGHER
TERRAIN IN THE POCONOS, SO NO ADVISORY WILL BE ISSUED AT THIS TIME.
OUR BIGGEST UNCERTAINTY REMAINS WITH THE WIND AND TO A CERTAIN
DEGREE ITS TIED TO THE TEMPERATURES. THE FORECAST SOUNDINGS REMAIN
VERY BULLISH ON DEEP MIXING AND ALBEIT TAKING THE HIGHER LEVEL OF
THE TWO BUFKIT MOMENTUM TRANSPORT WINDS GIVE US ADVISORY LEVEL WIND
GUSTS. OF LATE THE SFC GUSTS HAVE BEEN BETTER REPRESENTED BY THE
LOWER TRANSPORT GUST WHICH SUGGEST INTO THE 30S FOR GUSTS. THERE MAY
BE A WINDOW OF OPPORTUNITY FOR MORE ROBUST GUSTS THAN WE ARE
FORECASTING BEFORE THE SHOWERS ARRIVE AND MAKE THE SOUNDING MORE
ISOTHERMAL. THIS WILL DEPEND ON TEMPERATURES JUMPING THIS MORNING
BEFORE THE SHOWERS ARRIVE AND GETTING HIGHER THAN WE ARE CURRENTLY
ANTICIPATING. WHETHER ITS THE CHILLY BAYS OR OCEAN OR SKY COVER, MOS
GUIDANCE REMAINS PRETTY CONSERVATIVE WITH MAX TEMPS (AND WITH THE
WINDS TOO). WE STAYED CLOSE TO THEM NORTHWEST OF I95, BUT WERE MORE
BULLISH THAN BOTH SOUTHEAST.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/...
THE COLD FRONT SHOULD CLEAR OUR CWA EARLY THIS EVENING AND ANOTHER
COLD AIR MASS WILL START WORKING ITS WAY INTO OUR CWA. ANY POPS AWAY
FROM THE HIGHER TERRAIN WERE IN JUST EARLY IN THE EVENING. THERE
ARE MODEL DIFFERENCES AS TO HOW QUICKLY THE LAKE EFFECT MACHINE GETS
GOING. EVEN WITHOUT IT, THERE ARE ENOUGH SHORT WAVES MOVING THROUGH
TO LIKELY TRIGGER SOME SNOW SHOWERS NORTHWEST AND WE KEPT POPS GOING.
LIKE TODAY, WE THINK STAT GUIDANCE MAY BE A BIT TOO WEAK WITH THE
WINDS. GIVEN THE STRONG CAA, WE WENT HIGHER. IN TANDEM WE WERE ALSO
LOWER THAN STAT GUIDANCE WITH THE MIN TEMPS.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
THE SYNOPTIC SETUP IS AN ACTIVE ONE AND IS INITIALLY COMPRISED OF A
STRONG UPPER-LEVEL TROUGH IN THE NORTHEAST WITH ANOTHER ONE DIGGING
ACROSS THE INTERMOUNTAIN WEST. THE FIRST ONE EXITS THROUGH THURSDAY,
THEN THE BROADENING OF THE TROUGH IN THE WEST HAS SOME ENERGY THAT
EJECTS INTO THE PLAINS AND OHIO VALLEY. THIS SYSTEM MAY BECOME
STRETCHED OUT AS IT WEAKENS DUE TO THE MAIN TROUGH DAMPENING OUT
WHILE IT RELOADS ONCE AGAIN IN THE WEST. THE SOUTHERN JET LOOKS TO
REMAIN ACTIVE, THEREFORE ENERGY TRAVERSING THIS CORRIDOR WILL TEND
TO SLIDE OFF THE MID ATLANTIC COAST. WE MAY SEE THE SYSTEM ORGANIZE
MORE AS IT EXITS OFF THE MID ATLANTIC COAST DURING THE WEEKEND AS
SHORT WAVE ENERGY SHARPENS A BIT AND INCREASING BAROCLINIC EFFECTS
OCCUR. YET ANOTHER LARGE STORM LOOKS TO EJECT INTO THE PLAINS EARLY
NEXT WEEK WITH ITS COLD FRONT /OR EVEN OCCLUDED FRONT/ APPROACHING
FROM THE WEST MONDAY NIGHT. WE USED A MODEL BLEND FOR WEDNESDAY INTO
FRIDAY, THEN USED HPC GUIDANCE AND CONTINUITY THEREAFTER.
FOR WEDNESDAY AND THURSDAY...AN UPPER-LEVEL TROUGH IS FORECAST TO
DOMINATE THE NORTHEAST AS LOW PRESSURE TRACKS ACROSS SOUTHEASTERN
CANADA AND NEW ENGLAND, THEN EVENTUALLY TO THE CANADIAN MARITIMES.
THERE IS DECENT 850 MB CAA FORECAST WEDNESDAY BEFORE IT BACKS OFF
WEDNESDAY NIGHT AND THURSDAY. THE COMBINATION OF THE CAA AND A TIGHT
PRESSURE GRADIENT LEADS TO BLUSTERY CONDITIONS. THIS LOOKS SIMILAR
TO THIS PAST SUNDAY, HOWEVER THE MID LEVEL COLD CORE IS FORECAST TO
NOT BE QUITE AS COLD COMPARED TO SUNDAY. DESPITE THIS, VERTICAL
MIXING WILL DEEPEN WEDNESDAY AND THE FORECAST SOUNDINGS SHOW GUSTS
TO NEAR 35 KNOTS ARE CERTAINLY POSSIBLE. THE FLOW AT 925 MB IS
FORECAST TO BE MAINLY IN THE 30-35 KNOT RANGE WITH SOME HIGHER WINDS
AT 850 MB. IF WE ARE ABLE TO MIX EVEN DEEPER, THEN SOME NEAR ADVISORY
LEVEL GUSTS /40 KNOTS/ WILL BE POSSIBLE. WE WOULD LIKE TO SEE
WINDS CLOSER TO 50 KNOTS AT 850 MB FOR ADVISORY LEVEL WINDS,
THEREFORE WE WILL CONTINUE WITH GUSTS UNDER CRITERIA HOWEVER IT
WILL STILL BE A BLUSTERY/WINDY DAY.
THE GUSTY WINDS SHOULD CONTINUE WEDNESDAY NIGHT DESPITE WHEN WE
TYPICALLY SEE THEM DECOUPLE. THE PRESENT OF ENOUGH OF A MIXED LAYER
WILL KEEP AT LEAST SOME WIND GOING THROUGH THE NIGHT. THE AIRMASS
STARTS TO MODIFY DURING THURSDAY HOWEVER THE WESTERN EDGE OF THE MID
LEVEL COLD CORE IS NEARBY AND THIS WILL STILL COMBINE WITH A
LINGERING TIGHTENED PRESSURE GRADIENT TO RESULT IN BRISK CONDITIONS.
THESE WINDS WILL EASE UP AND BECOME NORTHERLY LATER THURSDAY AS HIGH
PRESSURE BUILDS DOWN FROM NEAR THE GREAT LAKES.
THE CAA ALONG WITH A NORTHWEST FLOW WILL PRODUCE LAKE EFFECT SNOW
DOWNWIND OF LAKES ERIE AND ONTARIO. THIS FLOW LOOKS CONDUCIVE TO
CARRY SOME STREAMERS INTO NORTHEASTERN PENNSYLVANIA, THEREFORE WE
WILL CARRY HIGHER CHC POPS INTO THE POCONOS FOR AT LEAST SCATTERED
SNOW SHOWERS. THIS SHOULD EASE UP ESPECIALLY THURSDAY AS THE AIRMASS
STARTS TO MODIFY AND THE FLOW MAY TURN MORE NORTHERLY.
FOR FRIDAY AND SATURDAY...THERE IS GENERALLY LOWER CONFIDENCE DURING
THIS TIME FRAME AS OUR SENSIBLE WEATHER IS FROM ENERGY THAT BECOMES
STRETCHED OUT FROM THE MIDWEST TO THE OHIO VALLEY AND SOUTHWARD.
HIGH PRESSURE CENTERED ACROSS SOUTHEASTERN CANADA LOOKS TO BE WEDGED
DOWN INTO THE MID ATLANTIC FOR A TIME FRIDAY. THIS MAY RESULT IN
SOME COLDER LOW-LEVEL AIR REMAINING WHILE WARMING TAKES PLACE ALOFT.
THE PRECIPITATION SHIELD WITH THIS INCOMING SYSTEM MAY END UP
SPLITTING, WITH THE MORE ORGANIZED AREA TO OUR SOUTH. WHILE WE HAVE
WAA, THE ISENTROPIC UPGLIDE AND ASSOCIATED LARGE SCALE ASCENT LOOKS
WEAKER OVER OUR AREA. THIS COULD JUST RESULT IN SOME LIGHT
PRECIPITATION. THERE LOOKS TO BE ENOUGH DRY AIR IN PLACE AHEAD OF
THIS FEATURE, WHERE THE PRECIPITATION DOES NOT START UNTIL LATER IN
THE DAY FRIDAY.
THERE DOES LOOK TO BE ENOUGH ENERGY IN THE SOUTHWEST FLOW ALOFT TO
ORGANIZE A SURFACE LOW, WHICH THEN TRACKS TO OUR SOUTH SATURDAY.
THIS COULD KEEP MORE OF AN EASTERLY WIND ACROSS OUR AREA ALONG WITH
COOLER TEMPERATURES. AT THIS JUNCTURE, PRECIPITATION LOOKS TO BE ON
THE LIGHT TO MODERATE SIDE UNLESS THE SYSTEM TRACKING OFF THE MID
ATLANTIC COAST CAN STRENGTHEN SOME MORE WHICH RESULTS IN STRONGER
LIFT SPREADING NORTHWARD. THE ECMWF IS INDICATING THIS POTENTIAL BUT
ALSO MAINTAINS THE PROGRESSIVE LOOK AS WELL. GIVEN MORE UNCERTAINTY
IN THE QPF AMOUNTS AND THERMAL FIELDS, WE DID NOT CHANGE MUCH FROM
CONTINUITY. OVERALL, MAINLY SOME RAIN ACROSS THE SOUTHERN AREAS WITH
THE CHC FOR A WINTRY MIX AT TIMES FARTHER NORTH.
FOR SUNDAY...LOW PRESSURE SHOULD BE EXITING THE MID ATLANTIC COAST
DURING THE MORNING AS A SHORT WAVE TROUGH AMPLIFIES SOME. THERE IS
SOME GUIDANCE THAT SUGGESTS THE SYSTEM IS SLOWER/A BIT STRONGER AND
THEREFORE INTRODUCES MORE PRECIPITATION FOR SUNDAY. AS OF NOW, WE
FOLLOWED HPC`S LEAD AND KEPT THE CONSOLIDATED SURFACE LOW EXITING TO
OUR EAST SUNDAY MORNING. THIS WOULD MEAN PERHAPS SOME PRECIPITATION
TO START, THE HIGH PRESSURE BEGINS TO BUILD IN. THE OVERALL
UPPER-LEVEL TROUGH DOES NOT LOOK TO AMPLIFY MUCH OVER OUR AREA
DURING THIS TIME FRAME, THUS THE FLOW BEING PROGRESSIVE. SOME COOLER
AIR LOOKS TO TRY AND SETTLE SOUTHWARD AS THE SURFACE LOW EXITS,
THEREFORE PERHAPS SOME MIXED PRECIPITATION OR SNOW BEFORE IT ENDS
ACROSS THE NORTH ESPECIALLY. WE DID NOT MAKE TO MANY CHANGES DUE TO
LOWER CONFIDENCE IN THE DETAILS.
FOR MONDAY...THE ACTIVE PATTERN CONTINUES AND THIS FEATURES
AN AMPLIFYING UPPER-LEVEL TROUGH MOVING EASTWARD. THIS WILL DRIVE
LOW PRESSURE ACROSS THE PLAINS MONDAY. THIS SYSTEM LOOKS TO
OCCLUDE WITH ANOTHER SURFACE LOW DEVELOPING FARTHER SOUTH ALONG THE
TRIPLE POINT. THERE IS A DECENT RIDGE BUILDING DOWNSTREAM OF THE
TROUGH, AND THIS WOULD HELP TO PULL MORE MOISTURE NORTHWARD AHEAD OF
THE FRONTAL BOUNDARY. THE LARGE SCALE LIFT LOOKS STRONGER WITH THIS
SYSTEM, AND IT COULD BE ENHANCED SOME AS THE SOUTHERN SURFACE LOW
TRACKS NORTHEASTWARD. WE WENT WITH A DRY MONDAY AS MID LEVEL RIDGING
ARRIVES, ALTHOUGH CLOUDS WILL INCREASE MAINLY LATE.
&&
.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
HAVE SLOWED DOWN ONSET OF PRECIP BASED ON CURRENT RADAR TRENDS AND
TWEAKED WINDS DOWN A BIT FOR THE NEXT FEW HOURS, BUT OVERALL FCST
REMAINS ON TRACK.
DURING THE SECOND HALF OF THE MORNING WE ARE FORECASTING SHOWERS
TO SPREAD ACROSS THE REST OF THE TERMINALS AND REACHING ACY BY
18Z. CONDITIONS WHEN SHOWERS FIRST ARRIVE ARE VFR TO OUR WEST. THE
FORECAST SOUNDINGS ARE SHOWING CONSIDERABLE GUSTINESS. WE WENT
WITH THE MORE CONSERVATIVE SUGGESTION. CONFIDENCE IS LOWER THAN
AVERAGE ABOUT THE WIND GUSTS. UNIDIRECTIONAL SOUTH WINDS, SO ONCE
THE GUSTINESS STARTS, THE LLWS SHOULD END.
DURING THE AFTERNOON WE BROUGHT THE TERMINALS DOWN INTO MVFR AS
THE MORE WIDESPREAD AND HEAVIER SHOWERS MOVE ACROSS THE REGION. AS
THE SHOWERS MOVE IN, THE GUSTINESS SHOULD DECREASE. THERE SHOULD BE
A LULL IN THE WIND ONCE PRECIPITATION MOVES OUT LATE IN THE
AFTERNOON. THIS MIGHT BE A PERIOD WHERE AN IFR CIG OR IFR VSBYS
MIGHT OCCUR. WE LOWERED CIGS AND VSBYS DEEPER INTO MVFR LEVELS BUT
WERE NOT CONFIDENT TO GO IFR.
THE COLD FRONT IS FORECAST TO MOVE THROUGH THE AREA FROM WEST TO
EAST APPROXIMATELY 23Z TO 02Z. ONCE IT DOES, VFR CONDITIONS
SHOULD RETURN, BUT ALSO SOME OCCASIONALLY GUSTY WEST WINDS.
OUTLOOK...
WEDNESDAY...VFR. NORTHWEST WINDS 15-20 KNOTS WITH GUSTS TO AROUND
30 KNOTS. SOME SNOW SHOWERS SHOULD BE NORTH AND WEST OF KABE.
THURSDAY...VFR. NORTH-NORTHWEST WINDS 15-20 KNOTS WITH GUSTS TO
AROUND 25 KNOTS, DIMINISHING AT NIGHT.
FRIDAY...CLOUDS INCREASE, THEREFORE VFR TO MVFR. SOME RAIN ARRIVES
MAINLY LATER IN THE DAY WITH IFR POSSIBLE, AND THERE COULD BE A
WINTRY MIX FOR A TIME MAINLY NORTH OF A KTTN TO KABE LINE.
EAST-SOUTHEAST WINDS NEAR 10 KNOTS.
SATURDAY...SUB-VFR WITH PERIODS OF RAIN POSSIBLE, WITH PERHAPS A
WINTRY MIX NORTH AND WEST OF KPHL. EASTERLY WINDS NEAR 10 KNOTS,
PROBABLY TURNING NORTHERLY AT NIGHT.
&&
.MARINE...
THE SMALL CRAFT ADVISORY REMAINS IN EFFECT THROUGH THE SHORT TERM.
WHILE AN APPROXIMATE 50 KT LLJ IS FORECAST TO MOVE OVER THE AREA
WATERS LATER TODAY, THE AIR MASS WILL BE WARMER THAN THE BAY AND
OCEAN TEMPS. SO WE ARE NOT EXPECTING EFFICIENT MIXING. IF WE ARE
WRONG, ITS LIKELY TO BE RIGHT ALONG THE IMMEDIATE COAST. HIGHER
CONFIDENCE ABOUT THE WIND SPEED FORECASTS FARTHER OFFSHORE.
THERE MIGHT BE A LULL IN THE WINDS THIS EVENING AS THE FRONT MOVES
THROUGH, BUT THEN SCA LEVEL WINDS (AS WELL AS SEAS CONTINUING ON THE
OCEAN) SHOULD COME BACK IN FULL SWING AFTER A SMALL TIME GAP.
OUTLOOK...
A COLD NORTHWESTERLY FLOW WILL OCCUR WEDNESDAY AND THURSDAY AS LOW
PRESSURE IS TO OUR NORTHEAST, ALLOWING FOR A TIGHTENED PRESSURE
GRADIENT TO BE IN PLACE. THIS WILL COMBINE WITH CAA, WHICH LOOKS TO
PEAK LATER WEDNESDAY BEFORE SOME MODERATION TAKES PLACE DURING
THURSDAY. THE FORECAST SOUNDINGS SHOW DEEPER MIXING OCCURRING AS WE
GO THROUGH WEDNESDAY, WITH A SOLID SMALL CRAFT ADVISORY EVENT
LOOKING TO OCCUR. THE FORECAST SOUNDINGS ALSO INDICATE THAT SOME
GALE FORCE GUSTS COULD OCCUR, HOWEVER IT LOOKS MARGINAL BASED ON THE
VERTICAL WIND PROFILES. WE THOUGHT ABOUT ISSUING A GALE WATCH FOR
WEDNESDAY NIGHT, HOWEVER WE WOULD LIKE TO SEE HIGHER WINDS WITHIN
THE MIXING LAYER. THEREFORE, WE WILL MAINTAIN THE SMALL CRAFT
ADVISORY BUT EXTEND IT THROUGH 11Z THURSDAY. THIS WILL PROBABLY NEED
TO BE EXTENDED THROUGH THURSDAY AS THE TIGHT PRESSURE GRADIENT HOLDS
FOR A TIME. THE WINDS START DIMINISHING LATER THURSDAY AS HIGH
PRESSURE CENTERED TO OUR NORTH ARRIVES. THE NEXT SYSTEM THOUGH IS
FORECAST TO ARRIVE LATER FRIDAY INTO SATURDAY, WITH WINDS
SHIFTING FROM NORTHERLY TO MORE OF AN EASTERLY DIRECTION.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST THURSDAY FOR ANZ430-431-
450>455.
&&
$$
SYNOPSIS...GORSE
NEAR TERM...GIGI/NIERENBERG
SHORT TERM...GIGI
LONG TERM...GORSE
AVIATION...GIGI/GORSE/NIERENBERG
MARINE...GIGI/GORSE
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
611 AM EST TUE FEB 19 2013
.SYNOPSIS...
LOW PRESSURE WILL TRACK FROM THE GREAT LAKES REGION TODAY, THEN
ACROSS SOUTHEASTERN CANADA TO NORTHERN NEW ENGLAND TONIGHT AND
WEDNESDAY. AN ASSOCIATED COLD FRONT WILL SLIDE ACROSS OUR AREA
THIS EVENING. HIGH PRESSURE FROM CENTRAL CANADA WILL THEN BUILD
SOUTH AND EASTWARD THURSDAY. THIS HIGH WILL BE SHIFTING EAST LATE
THURSDAY INTO FRIDAY, AS ANOTHER LOW PRESSURE SYSTEM MOVES INTO THE
GREAT LAKES AND OHIO VALLEY FRIDAY NIGHT INTO SATURDAY. LOW PRESSURE
FARTHER SOUTH ON THE COLD FRONT THEN EXITS THE MID ATLANTIC COAST
SATURDAY NIGHT INTO SUNDAY. HIGH PRESSURE THEN ARRIVES LATE SUNDAY
INTO MONDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THE ESTF UPDATE SPED THE ARRIVAL OF PCPN SLIGHTLY FASTER. LOOKS
LIKE THE 06Z GFS WILL VERIFY PRETTY CLOSELY AT 12Z. SNOW WAS
FALLING RELATIVELY SOUTH IN SWRN PA, SO WE HAVE EXPANDED THE
MENTION FARTHER TO THE SOUTH. THE GOOD NEWS IS IF PRECIPITATION
ARRIVES FASTER, THIS WILL CUT BACK ON OUR WIND CONCERNS.
THE GFS INITIALIZATION LOOKED SLIGHTLY BETTER THAN THE WRF-NMMB AND
THE FORECAST PACKAGE WAS LEANED ABOUT THREE QUARTERS TOWARD ITS
TIMING. WE DID OPT FOR THE WRF-NMMB SFC THERMAL FIELDS OVER THE GFS
IN THE POCONOS.
THE OVERALL FORCING STILL LOOKS SPLIT. THE FCST ISENTROPIC LIFT IS
NOT ROBUST, THE MID LEVEL QVEC CONVERGENCE AND FGEN FORCING WEAKEN
AS IT MOVES ACROSS THE APPALACHIANS. THE LOW LEVEL THETA E RIDGE IS
NOT ANYTHING TO WRITE HOME FOR (PLENTY OF LOW SFC DEW POINTS INTO
GEORGIA). THE BEST "CONVECTIVE" CONTRIBUTION GOES NORTHWEST OF CWA.
WHAT IT STILL DOES HAVE GOING FOR IT IS THE EXIT REGION OF THE 250MB
JET. WE SAW WHAT THAT DID FOR THE SYSTEM LAST FRIDAY NIGHT AND WE
ARE COUNTING ON IT TO SAVE THE QPF DAY.
SENSIBLE WEATHER, WE START BRINGING IN THE POPS AT 14Z, CLOSER TO
THE GFS TIMING. THERE IS PLENTY OF DRY AIR FOR THIS MOISTURE TO
OVERCOME, SO WE BELIEVE IT WILL TAKE A COUPLE OF HOURS FOR PCPN TO
GET GOING (EARLY TO MID AFTERNOON). THIS ALSO COINCIDES BETTER WITH
THE JET. THE THETA E RIDGE GETS OFFSHORE PRETTY FAST AND THE FCST
MID LVL WAA IS WAY EAST BY 00Z, SO POPS WERE DROPPED LATE IN THE
AFTERNOON IN THE WEST.
FOR PTYPE, THE DRY AIR MASS IN PLACE WILL MAKE IT EASY TO EVAPORATE
COOL TO SNOW. THE QUESTION IS HOW DEEP WILL THE THERMAL SOUNDING
HAVE TO BE COOLED FOR SNOW. THE LATEST ACAR SOUNDING FROM PHL
ALREADY HAS THE FREEZING LEVEL ABOVE 6K. SO THE "MENTION" OF SNOW
WAS LIMITED TO THE PHL FAR NWRN SUBURBS, RARITAN BASIN IN NJ AND
POINTS NW. THE LATER ARRIVAL TIME AND LIKELY LIGHT INTENSITY
START HAS PRETTY MUCH REMOVED THE RISK FOR FREEZING RAIN.
THE ONLY LOCALE THAT SHOULD HANG ON TO SNOW ARE THE POCONOS WHERE
THE WRF/HI RES ARW/ AND HRRR ALL DROP SFC TEMPS TO FREEZING AND
LEVEL THEM THERE. LATE IN THE DAY SOME SOUNDINGS SUGGEST WE LOSE THE
ICE AND WITH LESSER INTENSITY AND A CONTINUING SOUTH WIND, THE SNOW
COULD MIX OR CHANGE TO RAIN EVEN THERE. AS MENTIONED ABOVE THE MID
LEVEL FGEN FORCING WEAKENS AND THE BEST FGEN FRCG THAT MAKES IT
ACROSS THE MOUNTAINS REMAINS TOWARD THE 500MB LEVEL, COMES AS NO
SURPRISE THAT THE BEST OMEGA IS FCST TO ABOVE THE SNOW GROWTH AREA.
THIS COMBINED WITH MODEL QPFS OF AROUND A QUARTER OF AN INCH SUGGEST
AN INCH OR TWO OF SNOW AS THE MOST LIKELY OUTCOME FOR THE HIGHER
TERRAIN IN THE POCONOS, SO NO ADVISORY WILL BE ISSUED AT THIS TIME.
OUR BIGGEST UNCERTAINTY REMAINS WITH THE WIND AND TO A CERTAIN
DEGREE ITS TIED TO THE TEMPERATURES. THE FORECAST SOUNDINGS REMAIN
VERY BULLISH ON DEEP MIXING AND ALBEIT TAKING THE HIGHER LEVEL OF
THE TWO BUFKIT MOMENTUM TRANSPORT WINDS GIVE US ADVISORY LEVEL WIND
GUSTS. OF LATE THE SFC GUSTS HAVE BEEN BETTER REPRESENTED BY THE
LOWER TRANSPORT GUST WHICH SUGGEST INTO THE 30S FOR GUSTS. THERE MAY
BE A WINDOW OF OPPORTUNITY FOR MORE ROBUST GUSTS THAN WE ARE
FORECASTING BEFORE THE SHOWERS ARRIVE AND MAKE THE SOUNDING MORE
ISOTHERMAL. THIS WILL DEPEND ON TEMPERATURES JUMPING THIS MORNING
BEFORE THE SHOWERS ARRIVE AND GETTING HIGHER THAN WE ARE CURRENTLY
ANTICIPATING. WHETHER ITS THE CHILLY BAYS OR OCEAN OR SKY COVER, MOS
GUIDANCE REMAINS PRETTY CONSERVATIVE WITH MAX TEMPS (AND WITH THE
WINDS TOO). WE STAYED CLOSE TO THEM NORTHWEST OF I95, BUT WERE MORE
BULLISH THAN BOTH SOUTHEAST.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/...
THE COLD FRONT SHOULD CLEAR OUR CWA EARLY THIS EVENING AND ANOTHER
COLD AIR MASS WILL START WORKING ITS WAY INTO OUR CWA. ANY POPS AWAY
FROM THE HIGHER TERRAIN WERE IN JUST EARLY IN THE EVENING. THERE
ARE MODEL DIFFERENCES AS TO HOW QUICKLY THE LAKE EFFECT MACHINE GETS
GOING. EVEN WITHOUT IT, THERE ARE ENOUGH SHORT WAVES MOVING THROUGH
TO LIKELY TRIGGER SOME SNOW SHOWERS NORTHWEST AND WE KEPT POPS GOING.
LIKE TODAY, WE THINK STAT GUIDANCE MAY BE A BIT TOO WEAK WITH THE
WINDS. GIVEN THE STRONG CAA, WE WENT HIGHER. IN TANDEM WE WERE ALSO
LOWER THAN STAT GUIDANCE WITH THE MIN TEMPS.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
THE SYNOPTIC SETUP IS AN ACTIVE ONE AND IS INITIALLY COMPRISED OF A
STRONG UPPER-LEVEL TROUGH IN THE NORTHEAST WITH ANOTHER ONE DIGGING
ACROSS THE INTERMOUNTAIN WEST. THE FIRST ONE EXITS THROUGH THURSDAY,
THEN THE BROADENING OF THE TROUGH IN THE WEST HAS SOME ENERGY THAT
EJECTS INTO THE PLAINS AND OHIO VALLEY. THIS SYSTEM MAY BECOME
STRETCHED OUT AS IT WEAKENS DUE TO THE MAIN TROUGH DAMPENING OUT
WHILE IT RELOADS ONCE AGAIN IN THE WEST. THE SOUTHERN JET LOOKS TO
REMAIN ACTIVE, THEREFORE ENERGY TRAVERSING THIS CORRIDOR WILL TEND
TO SLIDE OFF THE MID ATLANTIC COAST. WE MAY SEE THE SYSTEM ORGANIZE
MORE AS IT EXITS OFF THE MID ATLANTIC COAST DURING THE WEEKEND AS
SHORT WAVE ENERGY SHARPENS A BIT AND INCREASING BAROCLINIC EFFECTS
OCCUR. YET ANOTHER LARGE STORM LOOKS TO EJECT INTO THE PLAINS EARLY
NEXT WEEK WITH ITS COLD FRONT /OR EVEN OCCLUDED FRONT/ APPROACHING
FROM THE WEST MONDAY NIGHT. WE USED A MODEL BLEND FOR WEDNESDAY INTO
FRIDAY, THEN USED HPC GUIDANCE AND CONTINUITY THEREAFTER.
FOR WEDNESDAY AND THURSDAY...AN UPPER-LEVEL TROUGH IS FORECAST TO
DOMINATE THE NORTHEAST AS LOW PRESSURE TRACKS ACROSS SOUTHEASTERN
CANADA AND NEW ENGLAND, THEN EVENTUALLY TO THE CANADIAN MARITIMES.
THERE IS DECENT 850 MB CAA FORECAST WEDNESDAY BEFORE IT BACKS OFF
WEDNESDAY NIGHT AND THURSDAY. THE COMBINATION OF THE CAA AND A TIGHT
PRESSURE GRADIENT LEADS TO BLUSTERY CONDITIONS. THIS LOOKS SIMILAR
TO THIS PAST SUNDAY, HOWEVER THE MID LEVEL COLD CORE IS FORECAST TO
NOT BE QUITE AS COLD COMPARED TO SUNDAY. DESPITE THIS, VERTICAL
MIXING WILL DEEPEN WEDNESDAY AND THE FORECAST SOUNDINGS SHOW GUSTS
TO NEAR 35 KNOTS ARE CERTAINLY POSSIBLE. THE FLOW AT 925 MB IS
FORECAST TO BE MAINLY IN THE 30-35 KNOT RANGE WITH SOME HIGHER WINDS
AT 850 MB. IF WE ARE ABLE TO MIX EVEN DEEPER, THEN SOME NEAR ADVISORY
LEVEL GUSTS /40 KNOTS/ WILL BE POSSIBLE. WE WOULD LIKE TO SEE
WINDS CLOSER TO 50 KNOTS AT 850 MB FOR ADVISORY LEVEL WINDS,
THEREFORE WE WILL CONTINUE WITH GUSTS UNDER CRITERIA HOWEVER IT
WILL STILL BE A BLUSTERY/WINDY DAY.
THE GUSTY WINDS SHOULD CONTINUE WEDNESDAY NIGHT DESPITE WHEN WE
TYPICALLY SEE THEM DECOUPLE. THE PRESENT OF ENOUGH OF A MIXED LAYER
WILL KEEP AT LEAST SOME WIND GOING THROUGH THE NIGHT. THE AIRMASS
STARTS TO MODIFY DURING THURSDAY HOWEVER THE WESTERN EDGE OF THE MID
LEVEL COLD CORE IS NEARBY AND THIS WILL STILL COMBINE WITH A
LINGERING TIGHTENED PRESSURE GRADIENT TO RESULT IN BRISK CONDITIONS.
THESE WINDS WILL EASE UP AND BECOME NORTHERLY LATER THURSDAY AS HIGH
PRESSURE BUILDS DOWN FROM NEAR THE GREAT LAKES.
THE CAA ALONG WITH A NORTHWEST FLOW WILL PRODUCE LAKE EFFECT SNOW
DOWNWIND OF LAKES ERIE AND ONTARIO. THIS FLOW LOOKS CONDUCIVE TO
CARRY SOME STREAMERS INTO NORTHEASTERN PENNSYLVANIA, THEREFORE WE
WILL CARRY HIGHER CHC POPS INTO THE POCONOS FOR AT LEAST SCATTERED
SNOW SHOWERS. THIS SHOULD EASE UP ESPECIALLY THURSDAY AS THE AIRMASS
STARTS TO MODIFY AND THE FLOW MAY TURN MORE NORTHERLY.
FOR FRIDAY AND SATURDAY...THERE IS GENERALLY LOWER CONFIDENCE DURING
THIS TIME FRAME AS OUR SENSIBLE WEATHER IS FROM ENERGY THAT BECOMES
STRETCHED OUT FROM THE MIDWEST TO THE OHIO VALLEY AND SOUTHWARD.
HIGH PRESSURE CENTERED ACROSS SOUTHEASTERN CANADA LOOKS TO BE WEDGED
DOWN INTO THE MID ATLANTIC FOR A TIME FRIDAY. THIS MAY RESULT IN
SOME COLDER LOW-LEVEL AIR REMAINING WHILE WARMING TAKES PLACE ALOFT.
THE PRECIPITATION SHIELD WITH THIS INCOMING SYSTEM MAY END UP
SPLITTING, WITH THE MORE ORGANIZED AREA TO OUR SOUTH. WHILE WE HAVE
WAA, THE ISENTROPIC UPGLIDE AND ASSOCIATED LARGE SCALE ASCENT LOOKS
WEAKER OVER OUR AREA. THIS COULD JUST RESULT IN SOME LIGHT
PRECIPITATION. THERE LOOKS TO BE ENOUGH DRY AIR IN PLACE AHEAD OF
THIS FEATURE, WHERE THE PRECIPITATION DOES NOT START UNTIL LATER IN
THE DAY FRIDAY.
THERE DOES LOOK TO BE ENOUGH ENERGY IN THE SOUTHWEST FLOW ALOFT TO
ORGANIZE A SURFACE LOW, WHICH THEN TRACKS TO OUR SOUTH SATURDAY.
THIS COULD KEEP MORE OF AN EASTERLY WIND ACROSS OUR AREA ALONG WITH
COOLER TEMPERATURES. AT THIS JUNCTURE, PRECIPITATION LOOKS TO BE ON
THE LIGHT TO MODERATE SIDE UNLESS THE SYSTEM TRACKING OFF THE MID
ATLANTIC COAST CAN STRENGTHEN SOME MORE WHICH RESULTS IN STRONGER
LIFT SPREADING NORTHWARD. THE ECMWF IS INDICATING THIS POTENTIAL BUT
ALSO MAINTAINS THE PROGRESSIVE LOOK AS WELL. GIVEN MORE UNCERTAINTY
IN THE QPF AMOUNTS AND THERMAL FIELDS, WE DID NOT CHANGE MUCH FROM
CONTINUITY. OVERALL, MAINLY SOME RAIN ACROSS THE SOUTHERN AREAS WITH
THE CHC FOR A WINTRY MIX AT TIMES FARTHER NORTH.
FOR SUNDAY...LOW PRESSURE SHOULD BE EXITING THE MID ATLANTIC COAST
DURING THE MORNING AS A SHORT WAVE TROUGH AMPLIFIES SOME. THERE IS
SOME GUIDANCE THAT SUGGESTS THE SYSTEM IS SLOWER/A BIT STRONGER AND
THEREFORE INTRODUCES MORE PRECIPITATION FOR SUNDAY. AS OF NOW, WE
FOLLOWED HPC`S LEAD AND KEPT THE CONSOLIDATED SURFACE LOW EXITING TO
OUR EAST SUNDAY MORNING. THIS WOULD MEAN PERHAPS SOME PRECIPITATION
TO START, THE HIGH PRESSURE BEGINS TO BUILD IN. THE OVERALL
UPPER-LEVEL TROUGH DOES NOT LOOK TO AMPLIFY MUCH OVER OUR AREA
DURING THIS TIME FRAME, THUS THE FLOW BEING PROGRESSIVE. SOME COOLER
AIR LOOKS TO TRY AND SETTLE SOUTHWARD AS THE SURFACE LOW EXITS,
THEREFORE PERHAPS SOME MIXED PRECIPITATION OR SNOW BEFORE IT ENDS
ACROSS THE NORTH ESPECIALLY. WE DID NOT MAKE TO MANY CHANGES DUE TO
LOWER CONFIDENCE IN THE DETAILS.
FOR MONDAY...THE ACTIVE PATTERN CONTINUES AND THIS FEATURES
AN AMPLIFYING UPPER-LEVEL TROUGH MOVING EASTWARD. THIS WILL DRIVE
LOW PRESSURE ACROSS THE PLAINS MONDAY. THIS SYSTEM LOOKS TO
OCCLUDE WITH ANOTHER SURFACE LOW DEVELOPING FARTHER SOUTH ALONG THE
TRIPLE POINT. THERE IS A DECENT RIDGE BUILDING DOWNSTREAM OF THE
TROUGH, AND THIS WOULD HELP TO PULL MORE MOISTURE NORTHWARD AHEAD OF
THE FRONTAL BOUNDARY. THE LARGE SCALE LIFT LOOKS STRONGER WITH THIS
SYSTEM, AND IT COULD BE ENHANCED SOME AS THE SOUTHERN SURFACE LOW
TRACKS NORTHEASTWARD. WE WENT WITH A DRY MONDAY AS MID LEVEL RIDGING
ARRIVES, ALTHOUGH CLOUDS WILL INCREASE MAINLY LATE.
&&
.AVIATION /11Z TUESDAY THROUGH SATURDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
THE 12Z TAFS WERE AGAIN SLIGHTLY FASTER WITH THE PCPN STARTER BUT
OTHERWISE CONTINUE THE IDEAS OF LLWS AND MORE GUSTINESS ALONG WITH
A DROP INTO MVFR LEVELS ONCE PRECIPITATION STARTS.
FOR THE FIRST PART OF THE MORNING, CLOUDS WILL COME IN FAST. WE
ADDED THE CHANCE OF SOME SNOW AT THE START AT KRDG AND KABE. LLWS
WAS CONTINUED FROM THE START WITH A SW LLJ AVERAGING 40 TO 45 KTS.
DURING THE SECOND HALF OF THE MORNING WE ARE FORECASTING SHOWERS
TO SPREAD ACROSS THE REST OF THE TERMINALS AND REACHING ACY BY
18Z. CONDITIONS WHEN SHOWERS FIRST ARRIVE ARE VFR TO OUR WEST. THE
FORECAST SOUNDINGS ARE SHOWING CONSIDERABLE GUSTINESS. WE WENT
WITH THE MORE CONSERVATIVE SUGGESTION. CONFIDENCE IS LOWER THAN
AVERAGE ABOUT THE WIND GUSTS. UNIDIRECTIONAL SOUTH WINDS, SO ONCE
THE GUSTINESS STARTS, THE LLWS SHOULD END.
DURING THE AFTERNOON WE BROUGHT THE TERMINALS DOWN INTO MVFR AS
THE MORE WIDESPREAD AND HEAVIER SHOWERS MOVE ACROSS THE REGION. AS
THE SHOWERS MOVE IN, THE GUSTINESS SHOULD DECREASE. THERE SHOULD BE
A LULL IN THE WIND ONCE PRECIPITATION MOVES OUT LATE IN THE
AFTERNOON. THIS MIGHT BE A PERIOD WHERE AN IFR CIG OR IFR VSBYS
MIGHT OCCUR. WE LOWERED CIGS AND VSBYS DEEPER INTO MVFR LEVELS BUT
WERE NOT CONFIDENT TO GO IFR.
THE COLD FRONT IS FORECAST TO MOVE THROUGH THE AREA FROM WEST TO
EAST APPROXIMATELY 23Z TO 02Z. ONCE IT DOES, VFR CONDITIONS
SHOULD RETURN, BUT ALSO SOME OCCASIONALLY GUSTY WEST WINDS.
OUTLOOK...
WEDNESDAY...VFR. NORTHWEST WINDS 15-20 KNOTS WITH GUSTS TO AROUND
30 KNOTS. SOME SNOW SHOWERS SHOULD BE NORTH AND WEST OF KABE.
THURSDAY...VFR. NORTH-NORTHWEST WINDS 15-20 KNOTS WITH GUSTS TO
AROUND 25 KNOTS, DIMINISHING AT NIGHT.
FRIDAY...CLOUDS INCREASE, THEREFORE VFR TO MVFR. SOME RAIN ARRIVES
MAINLY LATER IN THE DAY WITH IFR POSSIBLE, AND THERE COULD BE A
WINTRY MIX FOR A TIME MAINLY NORTH OF A KTTN TO KABE LINE.
EAST-SOUTHEAST WINDS NEAR 10 KNOTS.
SATURDAY...SUB-VFR WITH PERIODS OF RAIN POSSIBLE, WITH PERHAPS A
WINTRY MIX NORTH AND WEST OF KPHL. EASTERLY WINDS NEAR 10 KNOTS,
PROBABLY TURNING NORTHERLY AT NIGHT.
&&
.MARINE...
THE SMALL CRAFT ADVISORY REMAINS IN EFFECT THROUGH THE SHORT TERM.
WHILE AN APPROXIMATE 50 KT LLJ IS FORECAST TO MOVE OVER THE AREA
WATERS LATER TODAY, THE AIR MASS WILL BE WARMER THAN THE BAY AND
OCEAN TEMPS. SO WE ARE NOT EXPECTING EFFICIENT MIXING. IF WE ARE
WRONG, ITS LIKELY TO BE RIGHT ALONG THE IMMEDIATE COAST. HIGHER
CONFIDENCE ABOUT THE WIND SPEED FORECASTS FARTHER OFFSHORE.
THERE MIGHT BE A LULL IN THE WINDS THIS EVENING AS THE FRONT MOVES
THROUGH, BUT THEN SCA LEVEL WINDS (AS WELL AS SEAS CONTINUING ON THE
OCEAN) SHOULD COME BACK IN FULL SWING AFTER A SMALL TIME GAP.
OUTLOOK...
A COLD NORTHWESTERLY FLOW WILL OCCUR WEDNESDAY AND THURSDAY AS LOW
PRESSURE IS TO OUR NORTHEAST, ALLOWING FOR A TIGHTENED PRESSURE
GRADIENT TO BE IN PLACE. THIS WILL COMBINE WITH CAA, WHICH LOOKS TO
PEAK LATER WEDNESDAY BEFORE SOME MODERATION TAKES PLACE DURING
THURSDAY. THE FORECAST SOUNDINGS SHOW DEEPER MIXING OCCURRING AS WE
GO THROUGH WEDNESDAY, WITH A SOLID SMALL CRAFT ADVISORY EVENT
LOOKING TO OCCUR. THE FORECAST SOUNDINGS ALSO INDICATE THAT SOME
GALE FORCE GUSTS COULD OCCUR, HOWEVER IT LOOKS MARGINAL BASED ON THE
VERTICAL WIND PROFILES. WE THOUGHT ABOUT ISSUING A GALE WATCH FOR
WEDNESDAY NIGHT, HOWEVER WE WOULD LIKE TO SEE HIGHER WINDS WITHIN
THE MIXING LAYER. THEREFORE, WE WILL MAINTAIN THE SMALL CRAFT
ADVISORY BUT EXTEND IT THROUGH 11Z THURSDAY. THIS WILL PROBABLY NEED
TO BE EXTENDED THROUGH THURSDAY AS THE TIGHT PRESSURE GRADIENT HOLDS
FOR A TIME. THE WINDS START DIMINISHING LATER THURSDAY AS HIGH
PRESSURE CENTERED TO OUR NORTH ARRIVES. THE NEXT SYSTEM THOUGH IS
FORECAST TO ARRIVE LATER FRIDAY INTO SATURDAY, WITH WINDS
SHIFTING FROM NORTHERLY TO MORE OF AN EASTERLY DIRECTION.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO 6 AM EST
THURSDAY FOR ANZ430-431-450>455.
&&
$$
SYNOPSIS...GORSE
NEAR TERM...GIGI
SHORT TERM...GIGI
LONG TERM...GORSE
AVIATION...GIGI/GORSE
MARINE...GIGI/GORSE
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
338 AM EST TUE FEB 19 2013
.SYNOPSIS...
LOW PRESSURE WILL TRACK FROM THE GREAT LAKES REGION TODAY, THEN
ACROSS SOUTHEASTERN CANADA TO NORTHERN NEW ENGLAND TONIGHT AND
WEDNESDAY. AN ASSOCIATED COLD FRONT WILL SLIDE ACROSS OUR AREA
THIS EVENING. HIGH PRESSURE FROM CENTRAL CANADA WILL THEN BUILD
SOUTH AND EASTWARD THURSDAY. THIS HIGH WILL BE SHIFTING EAST LATE
THURSDAY INTO FRIDAY, AS ANOTHER LOW PRESSURE SYSTEM MOVES INTO THE
GREAT LAKES AND OHIO VALLEY FRIDAY NIGHT INTO SATURDAY. LOW PRESSURE
FARTHER SOUTH ON THE COLD FRONT THEN EXITS THE MID ATLANTIC COAST
SATURDAY NIGHT INTO SUNDAY. HIGH PRESSURE THEN ARRIVES LATE SUNDAY
INTO MONDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THE GFS INITIALIZATION LOOKED SLIGHTLY BETTER THAN THE WRF-NMMB AND
THE FORECAST PACKAGE WAS LEANED ABOUT THREE QUARTERS TOWARD ITS
TIMING. WE DID OPT FOR THE WRF-NMMB SFC THERMAL FIELDS OVER THE GFS
IN THE POCONOS.
THE OVERALL FORCING STILL LOOKS SPLIT. THE FCST ISENTROPIC LIFT IS
NOT ROBUST, THE MID LEVEL QVEC CONVERGENCE AND FGEN FORCING WEAKEN
AS IT MOVES ACROSS THE APPALACHIANS. THE LOW LEVEL THETA E RIDGE IS
NOT ANYTHING TO WRITE HOME FOR (PLENTY OF LOW SFC DEW POINTS INTO
GEORGIA). THE BEST "CONVECTIVE" CONTRIBUTION GOES NORTHWEST OF CWA.
WHAT IT STILL DOES HAVE GOING FOR IT IS THE EXIT REGION OF THE 250MB
JET. WE SAW WHAT THAT DID FOR THE SYSTEM LAST FRIDAY NIGHT AND WE
ARE COUNTING ON IT TO SAVE THE QPF DAY.
SENSIBLE WEATHER, WE START BRINGING IN THE POPS AT 14Z, CLOSER TO
THE GFS TIMING. THERE IS PLENTY OF DRY AIR FOR THIS MOISTURE TO
OVERCOME, SO WE BELIEVE IT WILL TAKE A COUPLE OF HOURS FOR PCPN TO
GET GOING (EARLY TO MID AFTERNOON). THIS ALSO COINCIDES BETTER WITH
THE JET. THE THETA E RIDGE GETS OFFSHORE PRETTY FAST AND THE FCST
MID LVL WAA IS WAY EAST BY 00Z, SO POPS WERE DROPPED LATE IN THE
AFTERNOON IN THE WEST.
FOR PTYPE, THE DRY AIR MASS IN PLACE WILL MAKE IT EASY TO EVAPORATE
COOL TO SNOW. THE QUESTION IS HOW DEEP WILL THE THERMAL SOUNDING
HAVE TO BE COOLED FOR SNOW. THE LATEST ACAR SOUNDING FROM PHL
ALREADY HAS THE FREEZING LEVEL ABOVE 6K. SO THE "MENTION" OF SNOW
WAS LIMITED TO THE PHL FAR NWRN SUBURBS, RARITAN BASIN IN NJ AND
POINTS NW. THE LATER ARRIVAL TIME AND LIKELY LIGHT INTENSITY
START HAS PRETTY MUCH REMOVED THE RISK FOR FREEZING RAIN.
THE ONLY LOCALE THAT SHOULD HANG ON TO SNOW ARE THE POCONOS WHERE
THE WRF/HI RES ARW/ AND HRRR ALL DROP SFC TEMPS TO FREEZING AND
LEVEL THEM THERE. LATE IN THE DAY SOME SOUNDINGS SUGGEST WE LOSE THE
ICE AND WITH LESSER INTENSITY AND A CONTINUING SOUTH WIND, THE SNOW
COULD MIX OR CHANGE TO RAIN EVEN THERE. AS MENTIONED ABOVE THE MID
LEVEL FGEN FORCING WEAKENS AND THE BEST FGEN FRCG THAT MAKES IT
ACROSS THE MOUNTAINS REMAINS TOWARD THE 500MB LEVEL, COMES AS NO
SURPRISE THAT THE BEST OMEGA IS FCST TO ABOVE THE SNOW GROWTH AREA.
THIS COMBINED WITH MODEL QPFS OF AROUND A QUARTER OF AN INCH SUGGEST
AN INCH OR TWO OF SNOW AS THE MOST LIKELY OUTCOME FOR THE HIGHER
TERRAIN IN THE POCONOS, SO NO ADVISORY WILL BE ISSUED AT THIS TIME.
OUR BIGGEST UNCERTAINTY REMAINS WITH THE WIND AND TO A CERTAIN
DEGREE ITS TIED TO THE TEMPERATURES. THE FORECAST SOUNDINGS REMAIN
VERY BULLISH ON DEEP MIXING AND ALBEIT TAKING THE HIGHER LEVEL OF
THE TWO BUFKIT MOMENTUM TRANSPORT WINDS GIVE US ADVISORY LEVEL WIND
GUSTS. OF LATE THE SFC GUSTS HAVE BEEN BETTER REPRESENTED BY THE
LOWER TRANSPORT GUST WHICH SUGGEST INTO THE 30S FOR GUSTS. THERE MAY
BE A WINDOW OF OPPORTUNITY FOR MORE ROBUST GUSTS THAN WE ARE
FORECASTING BEFORE THE SHOWERS ARRIVE AND MAKE THE SOUNDING MORE
ISOTHERMAL. THIS WILL DEPEND ON TEMPERATURES JUMPING THIS MORNING
BEFORE THE SHOWERS ARRIVE AND GETTING HIGHER THAN WE ARE CURRENTLY
ANTICIPATING. WHETHER ITS THE CHILLY BAYS OR OCEAN OR SKY COVER, MOS
GUIDANCE REMAINS PRETTY CONSERVATIVE WITH MAX TEMPS (AND WITH THE
WINDS TOO). WE STAYED CLOSE TO THEM NORTHWEST OF I95, BUT WERE MORE
BULLISH THAN BOTH SOUTHEAST.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/...
THE COLD FRONT SHOULD CLEAR OUR CWA EARLY THIS EVENING AND ANOTHER
COLD AIR MASS WILL START WORKING ITS WAY INTO OUR CWA. ANY POPS AWAY
FROM THE HIGHER TERRAIN WERE IN JUST EARLY IN THE EVENING. THERE
ARE MODEL DIFFERENCES AS TO HOW QUICKLY THE LAKE EFFECT MACHINE GETS
GOING. EVEN WITHOUT IT, THERE ARE ENOUGH SHORT WAVES MOVING THROUGH
TO LIKELY TRIGGER SOME SNOW SHOWERS NORTHWEST AND WE KEPT POPS GOING.
LIKE TODAY, WE THINK STAT GUIDANCE MAY BE A BIT TOO WEAK WITH THE
WINDS. GIVEN THE STRONG CAA, WE WENT HIGHER. IN TANDEM WE WERE ALSO
LOWER THAN STAT GUIDANCE WITH THE MIN TEMPS.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
THE SYNOPTIC SETUP IS AN ACTIVE ONE AND IS INITIALLY COMPRISED OF A
STRONG UPPER-LEVEL TROUGH IN THE NORTHEAST WITH ANOTHER ONE DIGGING
ACROSS THE INTERMOUNTAIN WEST. THE FIRST ONE EXITS THROUGH THURSDAY,
THEN THE BROADENING OF THE TROUGH IN THE WEST HAS SOME ENERGY THAT
EJECTS INTO THE PLAINS AND OHIO VALLEY. THIS SYSTEM MAY BECOME
STRETCHED OUT AS IT WEAKENS DUE TO THE MAIN TROUGH DAMPENING OUT
WHILE IT RELOADS ONCE AGAIN IN THE WEST. THE SOUTHERN JET LOOKS TO
REMAIN ACTIVE, THEREFORE ENERGY TRAVERSING THIS CORRIDOR WILL TEND
TO SLIDE OFF THE MID ATLANTIC COAST. WE MAY SEE THE SYSTEM ORGANIZE
MORE AS IT EXITS OFF THE MID ATLANTIC COAST DURING THE WEEKEND AS
SHORT WAVE ENERGY SHARPENS A BIT AND INCREASING BAROCLINIC EFFECTS
OCCUR. YET ANOTHER LARGE STORM LOOKS TO EJECT INTO THE PLAINS EARLY
NEXT WEEK WITH ITS COLD FRONT /OR EVEN OCCLUDED FRONT/ APPROACHING
FROM THE WEST MONDAY NIGHT. WE USED A MODEL BLEND FOR WEDNESDAY INTO
FRIDAY, THEN USED HPC GUIDANCE AND CONTINUITY THEREAFTER.
FOR WEDNESDAY AND THURSDAY...AN UPPER-LEVEL TROUGH IS FORECAST TO
DOMINATE THE NORTHEAST AS LOW PRESSURE TRACKS ACROSS SOUTHEASTERN
CANADA AND NEW ENGLAND, THEN EVENTUALLY TO THE CANADIAN MARITIMES.
THERE IS DECENT 850 MB CAA FORECAST WEDNESDAY BEFORE IT BACKS OFF
WEDNESDAY NIGHT AND THURSDAY. THE COMBINATION OF THE CAA AND A TIGHT
PRESSURE GRADIENT LEADS TO BLUSTERY CONDITIONS. THIS LOOKS SIMILAR
TO THIS PAST SUNDAY, HOWEVER THE MID LEVEL COLD CORE IS FORECAST TO
NOT BE QUITE AS COLD COMPARED TO SUNDAY. DESPITE THIS, VERTICAL
MIXING WILL DEEPEN WEDNESDAY AND THE FORECAST SOUNDINGS SHOW GUSTS
TO NEAR 35 KNOTS ARE CERTAINLY POSSIBLE. THE FLOW AT 925 MB IS
FORECAST TO BE MAINLY IN THE 30-35 KNOT RANGE WITH SOME HIGHER WINDS
AT 850 MB. IF WE ARE ABLE TO MIX EVEN DEEPER, THEN SOME NEAR ADVISORY
LEVEL GUSTS /40 KNOTS/ WILL BE POSSIBLE. WE WOULD LIKE TO SEE
WINDS CLOSER TO 50 KNOTS AT 850 MB FOR ADVISORY LEVEL WINDS,
THEREFORE WE WILL CONTINUE WITH GUSTS UNDER CRITERIA HOWEVER IT
WILL STILL BE A BLUSTERY/WINDY DAY.
THE GUSTY WINDS SHOULD CONTINUE WEDNESDAY NIGHT DESPITE WHEN WE
TYPICALLY SEE THEM DECOUPLE. THE PRESENT OF ENOUGH OF A MIXED LAYER
WILL KEEP AT LEAST SOME WIND GOING THROUGH THE NIGHT. THE AIRMASS
STARTS TO MODIFY DURING THURSDAY HOWEVER THE WESTERN EDGE OF THE MID
LEVEL COLD CORE IS NEARBY AND THIS WILL STILL COMBINE WITH A
LINGERING TIGHTENED PRESSURE GRADIENT TO RESULT IN BRISK CONDITIONS.
THESE WINDS WILL EASE UP AND BECOME NORTHERLY LATER THURSDAY AS HIGH
PRESSURE BUILDS DOWN FROM NEAR THE GREAT LAKES.
THE CAA ALONG WITH A NORTHWEST FLOW WILL PRODUCE LAKE EFFECT SNOW
DOWNWIND OF LAKES ERIE AND ONTARIO. THIS FLOW LOOKS CONDUCIVE TO
CARRY SOME STREAMERS INTO NORTHEASTERN PENNSYLVANIA, THEREFORE WE
WILL CARRY HIGHER CHC POPS INTO THE POCONOS FOR AT LEAST SCATTERED
SNOW SHOWERS. THIS SHOULD EASE UP ESPECIALLY THURSDAY AS THE AIRMASS
STARTS TO MODIFY AND THE FLOW MAY TURN MORE NORTHERLY.
FOR FRIDAY AND SATURDAY...THERE IS GENERALLY LOWER CONFIDENCE DURING
THIS TIME FRAME AS OUR SENSIBLE WEATHER IS FROM ENERGY THAT BECOMES
STRETCHED OUT FROM THE MIDWEST TO THE OHIO VALLEY AND SOUTHWARD.
HIGH PRESSURE CENTERED ACROSS SOUTHEASTERN CANADA LOOKS TO BE WEDGED
DOWN INTO THE MID ATLANTIC FOR A TIME FRIDAY. THIS MAY RESULT IN
SOME COLDER LOW-LEVEL AIR REMAINING WHILE WARMING TAKES PLACE ALOFT.
THE PRECIPITATION SHIELD WITH THIS INCOMING SYSTEM MAY END UP
SPLITTING, WITH THE MORE ORGANIZED AREA TO OUR SOUTH. WHILE WE HAVE
WAA, THE ISENTROPIC UPGLIDE AND ASSOCIATED LARGE SCALE ASCENT LOOKS
WEAKER OVER OUR AREA. THIS COULD JUST RESULT IN SOME LIGHT
PRECIPITATION. THERE LOOKS TO BE ENOUGH DRY AIR IN PLACE AHEAD OF
THIS FEATURE, WHERE THE PRECIPITATION DOES NOT START UNTIL LATER IN
THE DAY FRIDAY.
THERE DOES LOOK TO BE ENOUGH ENERGY IN THE SOUTHWEST FLOW ALOFT TO
ORGANIZE A SURFACE LOW, WHICH THEN TRACKS TO OUR SOUTH SATURDAY.
THIS COULD KEEP MORE OF AN EASTERLY WIND ACROSS OUR AREA ALONG WITH
COOLER TEMPERATURES. AT THIS JUNCTURE, PRECIPITATION LOOKS TO BE ON
THE LIGHT TO MODERATE SIDE UNLESS THE SYSTEM TRACKING OFF THE MID
ATLANTIC COAST CAN STRENGTHEN SOME MORE WHICH RESULTS IN STRONGER
LIFT SPREADING NORTHWARD. THE ECMWF IS INDICATING THIS POTENTIAL BUT
ALSO MAINTAINS THE PROGRESSIVE LOOK AS WELL. GIVEN MORE UNCERTAINTY
IN THE QPF AMOUNTS AND THERMAL FIELDS, WE DID NOT CHANGE MUCH FROM
CONTINUITY. OVERALL, MAINLY SOME RAIN ACROSS THE SOUTHERN AREAS WITH
THE CHC FOR A WINTRY MIX AT TIMES FARTHER NORTH.
FOR SUNDAY...LOW PRESSURE SHOULD BE EXITING THE MID ATLANTIC COAST
DURING THE MORNING AS A SHORT WAVE TROUGH AMPLIFIES SOME. THERE IS
SOME GUIDANCE THAT SUGGESTS THE SYSTEM IS SLOWER/A BIT STRONGER AND
THEREFORE INTRODUCES MORE PRECIPITATION FOR SUNDAY. AS OF NOW, WE
FOLLOWED HPC`S LEAD AND KEPT THE CONSOLIDATED SURFACE LOW EXITING TO
OUR EAST SUNDAY MORNING. THIS WOULD MEAN PERHAPS SOME PRECIPITATION
TO START, THE HIGH PRESSURE BEGINS TO BUILD IN. THE OVERALL
UPPER-LEVEL TROUGH DOES NOT LOOK TO AMPLIFY MUCH OVER OUR AREA
DURING THIS TIME FRAME, THUS THE FLOW BEING PROGRESSIVE. SOME COOLER
AIR LOOKS TO TRY AND SETTLE SOUTHWARD AS THE SURFACE LOW EXITS,
THEREFORE PERHAPS SOME MIXED PRECIPITATION OR SNOW BEFORE IT ENDS
ACROSS THE NORTH ESPECIALLY. WE DID NOT MAKE TO MANY CHANGES DUE TO
LOWER CONFIDENCE IN THE DETAILS.
FOR MONDAY...THE ACTIVE PATTERN CONTINUES AND THIS FEATURES
AN AMPLIFYING UPPER-LEVEL TROUGH MOVING EASTWARD. THIS WILL DRIVE
LOW PRESSURE ACROSS THE PLAINS MONDAY. THIS SYSTEM LOOKS TO
OCCLUDE WITH ANOTHER SURFACE LOW DEVELOPING FARTHER SOUTH ALONG THE
TRIPLE POINT. THERE IS A DECENT RIDGE BUILDING DOWNSTREAM OF THE
TROUGH, AND THIS WOULD HELP TO PULL MORE MOISTURE NORTHWARD AHEAD OF
THE FRONTAL BOUNDARY. THE LARGE SCALE LIFT LOOKS STRONGER WITH THIS
SYSTEM, AND IT COULD BE ENHANCED SOME AS THE SOUTHERN SURFACE LOW
TRACKS NORTHEASTWARD. WE WENT WITH A DRY MONDAY AS MID LEVEL RIDGING
ARRIVES, ALTHOUGH CLOUDS WILL INCREASE MAINLY LATE.
&&
.AVIATION /09Z TUESDAY THROUGH SATURDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
THE 06Z TAFS WERE SLIGHTLY FASTER WITH THE PCPN STARTER BUT
OTHERWISE CONTINUE THE IDEAS OF LLWS AND MORE GUSTINESS ALONG WITH
A DROP INTO MVFR LEVELS ONCE PRECIPITATION STARTS.
FOR THE REST OF THE NIGHT INTO THE FIRST PART OF THE MORNING VFR
WITH HIGH CIGS AND NO VSBY RESTRICTIONS. ENOUGH WIND TO PREVENT FOG.
LLWS WAS CONTINUED FROM THE START WITH A SW LLJ AVERAGING 40 TO 45
KTS.
DURING THE SECOND HALF OF THE MORNING WE ARE FORECASTING SHOWERS
TO START SPREADING ACROSS THE TERMINALS AND REACHING ACY BY 18Z.
CONDITIONS WHEN SHOWERS FIRST ARRIVE ARE VFR TO OUR WEST. THE FORECAST
SOUNDINGS ARE SHOWING CONSIDERABLE GUSTINESS. WE WENT WITH THE MORE
CONSERVATIVE SUGGESTION. CONFIDENCE IS LOWER THAN AVERAGE ABOUT THE
WIND GUSTS. UNIDIRECTIONAL SOUTH WINDS, SO ONCE THE GUSTINESS
STARTS, THE LLWS SHOULD END.
DURING THE AFTERNOON WE BROUGHT THE TERMINALS DOWN INTO MVFR AS
THE MORE WIDESPREAD AND HEAVIER SHOWERS MOVE ACROSS THE REGION. AS
THE SHOWERS MOVE IN, THE GUSTINESS SHOULD DECREASE. THERE SHOULD BE
A LULL IN THE WIND ONCE PRECIPITATION MOVES OUT LATE IN THE
AFTERNOON. THIS MIGHT BE A PERIOD WHERE AN IFR CIG OR IFR VSBYS
MIGHT OCCUR. WE LOWERED CIGS AND VSBYS DEEPER INTO MVFR LEVELS BUT
WERE NOT CONFIDENT TO GO IFR.
THE COLD FRONT IS FORECAST TO MOVE THROUGH THE AREA FROM WEST TO
EAST APPROXIMATELY 23Z TO 02Z. ONCE IT DOES, VFR CONDITIONS
SHOULD RETURN, BUT ALSO SOME OCCASIONALLY GUSTY WEST WINDS.
OUTLOOK...
WEDNESDAY...VFR. NORTHWEST WINDS 15-20 KNOTS WITH GUSTS TO AROUND
30 KNOTS. SOME SNOW SHOWERS SHOULD BE NORTH AND WEST OF KABE.
THURSDAY...VFR. NORTH-NORTHWEST WINDS 15-20 KNOTS WITH GUSTS TO
AROUND 25 KNOTS, DIMINISHING AT NIGHT.
FRIDAY...CLOUDS INCREASE, THEREFORE VFR TO MVFR. SOME RAIN ARRIVES
MAINLY LATER IN THE DAY WITH IFR POSSIBLE, AND THERE COULD BE A
WINTRY MIX FOR A TIME MAINLY NORTH OF A KTTN TO KABE LINE.
EAST-SOUTHEAST WINDS NEAR 10 KNOTS.
SATURDAY...SUB-VFR WITH PERIODS OF RAIN POSSIBLE, WITH PERHAPS A
WINTRY MIX NORTH AND WEST OF KPHL. EASTERLY WINDS NEAR 10 KNOTS,
PROBABLY TURNING NORTHERLY AT NIGHT.
&&
.MARINE...
THE SMALL CRAFT ADVISORY REMAINS IN EFFECT THROUGH THE SHORT TERM.
WHILE AN APPROXIMATE 50 KT LLJ IS FORECAST TO MOVE OVER THE AREA
WATERS LATER TODAY, THE AIR MASS WILL BE WARMER THAN THE BAY AND
OCEAN TEMPS. SO WE ARE NOT EXPECTING EFFICIENT MIXING. IF WE ARE
WRONG, ITS LIKELY TO BE RIGHT ALONG THE IMMEDIATE COAST. HIGHER
CONFIDENCE ABOUT THE WIND SPEED FORECASTS FARTHER OFFSHORE.
THERE MIGHT BE A LULL IN THE WINDS THIS EVENING AS THE FRONT MOVES
THROUGH, BUT THEN SCA LEVEL WINDS (AS WELL AS SEAS CONTINUING ON THE
OCEAN) SHOULD COME BACK IN FULL SWING AFTER A SMALL TIME GAP.
OUTLOOK...
A COLD NORTHWESTERLY FLOW WILL OCCUR WEDNESDAY AND THURSDAY AS LOW
PRESSURE IS TO OUR NORTHEAST, ALLOWING FOR A TIGHTENED PRESSURE
GRADIENT TO BE IN PLACE. THIS WILL COMBINE WITH CAA, WHICH LOOKS TO
PEAK LATER WEDNESDAY BEFORE SOME MODERATION TAKES PLACE DURING
THURSDAY. THE FORECAST SOUNDINGS SHOW DEEPER MIXING OCCURRING AS WE
GO THROUGH WEDNESDAY, WITH A SOLID SMALL CRAFT ADVISORY EVENT
LOOKING TO OCCUR. THE FORECAST SOUNDINGS ALSO INDICATE THAT SOME
GALE FORCE GUSTS COULD OCCUR, HOWEVER IT LOOKS MARGINAL BASED ON THE
VERTICAL WIND PROFILES. WE THOUGHT ABOUT ISSUING A GALE WATCH FOR
WEDNESDAY NIGHT, HOWEVER WE WOULD LIKE TO SEE HIGHER WINDS WITHIN
THE MIXING LAYER. THEREFORE, WE WILL MAINTAIN THE SMALL CRAFT
ADVISORY BUT EXTEND IT THROUGH 11Z THURSDAY. THIS WILL PROBABLY NEED
TO BE EXTENDED THROUGH THURSDAY AS THE TIGHT PRESSURE GRADIENT HOLDS
FOR A TIME. THE WINDS START DIMINISHING LATER THURSDAY AS HIGH
PRESSURE CENTERED TO OUR NORTH ARRIVES. THE NEXT SYSTEM THOUGH IS
FORECAST TO ARRIVE LATER FRIDAY INTO SATURDAY, WITH WINDS
SHIFTING FROM NORTHERLY TO MORE OF AN EASTERLY DIRECTION.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO 6 AM EST
THURSDAY FOR ANZ430-431-450>455.
&&
$$
SYNOPSIS...GORSE
NEAR TERM...GIGI
SHORT TERM...GIGI
LONG TERM...GORSE
AVIATION...GIGI/GORSE
MARINE...GIGI/GORSE
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
344 AM EST TUE FEB 19 2013
.SYNOPSIS...
A COLD FRONT WILL MOVE THROUGH LATE TODAY...FOLLOWED BY HIGH
PRESSURE WEDNESDAY AND THURSDAY. A FRONTAL SYSTEM WILL MOVE INTO THE
AREA FOR FRIDAY THROUGH AT LEAST SATURDAY...BRINGING A GOOD CHANCE
FOR RAIN LATE IN THE WEEK INTO THE WEEKEND. HIGH PRESSURE SHOULD
BRIEFLY BUILD IN EARLY NEXT WEEK...BEFORE LIKELY GIVING WAY TO
ANOTHER FRONTAL SYSTEM.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
EARLY THIS MORNING...PATCHES OF STRATOCUMULUS CLOUDS IN THE 4 TO 6
KFT RANGE ARE MOVING ACROSS PORTIONS OF THE FORECAST AREA. THESE
CLOUDS...COMBINED WITH LOW LEVEL FLOW FINALLY PICKING UP OUT OF THE
S AND SE HAVE CAUSED TEMPS TO START RISING FROM THEIR EARLIER MINS.
HAVE REMOVED ANY MENTION OF COASTAL SHOWERS AFFECTING THE CHARLESTON
COUNTY BEACHES AS NO SHOWERS HAVE FORMED EVEN OUT TO 40 MILES
OFFSHORE. OTHERWISE...THE COLD FRONT IS STILL WELL TO THE WEST AND
HIGH PRESSURE TO THE EAST.
TODAY...A VIGOROUS CLOSED LOW AND ASSOCIATED MID/UPPER LEVEL TROUGH
WILL MOVE ACROSS THE GREAT LAKES REGION WITH MAINLY JUST SSW FLOW
OVER THE FORECAST AREA. THIS UPPER LEVEL FEATURE WILL DRIVE A SUB
990 MB SURFACE LOW OVER THE GREAT LAKES WITH A TRAILING COLD FRONT
MOVING ACROSS THE TN VALLEY AND THE SOUTHEAST. THIS COLD FRONT WILL
BE THE FORECAST PROBLEM OF THE DAY AND WILL DETERMINE HOW THE
SENSIBLE WEATHER PANS OUT. REGARDING PRECIP CHANCES AND THEIR
TIMING...THE MODELS AGREE IN SHOWING DEEP MOISTURE SPREADING INTO
THE FORECAST AREA WITHIN THE MODERATE DEEP LAYER SW FLOW. PWATS WILL
SURGE TO AROUND 1.10 INCHES IN MOST LOCATIONS WITH SOME VALUES EVEN
APPROACHING 1.25 INCHES IN SE GA. WHILE THIS IS MOIST FOR THIS TIME
OF YEAR...ITS NOT AN ABNORMAL DEGREE OF MOISTURE AND FALLS SOMEWHERE
AROUND THE 75TH PERCENTILE. AS NOTED ABOVE...THE MAIN UPPER LEVEL
ENERGY ASSOCIATED WITH THE TROUGH WILL BE UP ACROSS THE MIDWEST AND
THE GREAT LAKES REGION TODAY. THEREFORE THE UPPER LEVEL SUPPORT IS
SOMEWHAT MUTED THIS FAR SOUTH AND FORCING WILL PRIMARILY BE LIMITED
TO CONVERGENCE ALONG THE APPROACHING COLD FRONT. BASED ON THE LATEST
RUNS OF THE RAP AND OTHER HI-RES MODELS...I HAVE THE BULK OF THE
POPS IN THE FORECAST AREA DURING THE 17-22Z TIME FRAME. THE
CHARACTER OF THE PRECIP IS EXPECTED TO BE SHOWERS. SOUNDINGS DO NOT
YIELD ANY SURFACE BASED INSTABILITY AND LOOKING AT SHOWALTER VALUES
ONLY DEPICTS A SMALL AREA APPROACHING ZERO AROUND SE GA. THUS...THE
FORECAST JUST FEATURES SHOWERS WITH NO THUNDER. TOTAL RAINFALL
AMOUNTS ARE NOT EXPECTED TO BE OVERLY IMPRESSIVE AND SHOULD TOP OUT
AROUND A QUARTER OF AN INCH ACROSS FAR INLAND SE GA. THE FRONT AND
ITS CLOUD COVER WILL MAKE FOR A SOMEWHAT TRICKY MAX TEMP FORECAST.
GIVEN THAT MUCH OF THE CLOUD COVER WITH THE FRONT IS STILL WELL TO
THE WEST...IT STANDS TO REASON THAT MUCH OF THE MORNING WILL SEE AT
LEAST SOME SUNSHINE. WITH LOW LEVEL THICKNESSES SUPPORTING UPPER 60S
TO NEAR 70 WITHIN THE WARM SECTOR...TEMPS SHOULD WARM QUICKLY AFTER
SUNRISE AND THEN SLOW WITH THE ONSET OF THE CLOUD SHIELD. I HAVE
TEMPS RANGING IN THE LOW TO MID 60S...THOUGH SOME LOCATIONS
ESPECIALLY FURTHER EAST...MAY OUTPERFORM THESE VALUES. WITH THESE
TEMPS...WINDS WILL BECOME BREEZY IN THE MORNING...ESPECIALLY ALONG
AND EAST OF I-95.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
TONIGHT...THE FRONT WILL PUSH OFFSHORE QUICKLY WITH COOLER AND DRIER
AIR FILTERING IN. ANY LINGERING SHOWERS SHOULD BE DONE OVER LAND
AREAS BY THE LATE EVENING AND SKIES WILL CLEAR AS WELL. OVERALL THE
AIRMASS BEHIND THE FRONT IS NOT INCREDIBLY COLD. LOWS WILL FALL INTO
THE LOW TO MID 30S INLAND...WITH UPPER 30S TO LOW 40S CLOSER TO THE
BEACHES.
WEDNESDAY...A DEEP CLOSED LOW WILL SHIFT EAST INTO NEW
ENGLAND...WITH A STRONG SHORT WAVE TROUGH FOUND IN THE DESERT SW. IN
BETWEEN A HIGHLY AMPLIFIED RIDGE WILL COVER THE CENTRAL STATES INTO
SOUTH-CENTRAL CANADA. OUR FORECAST ZONES WILL LIE WITHIN A ZONAL
FLOW SOUTH OF THE CYCLONIC FLOW ASSOCIATED WITH THE DEEP LOW MOVING
TOWARD NEW ENGLAND. A SHORT WAVE LOCATED NEAR THE CALIFORNIA BAJA
TODAY WILL BE EMBEDDED WITHIN THE FAST MOVING FLOW ALOFT AND CROSSES
THE REGION LATE IN THE DAY. BUT SINCE THERE IS NO MOISTURE AVAILABLE
FOR IT TO UTILIZE...WITH PWATS NO HIGHER THAN 0.3-0.4
INCHES...RAIN FREE CONDITIONS WILL BE THE RULE. SUNNY SKIES IN THE
MORNING WILL GIVE WAY TO SOME JET STREAK CIRRUS IN THE
AFTERNOON...AS THEY INCREASE AND BECOME A LITTLE MORE OPAQUE LATE.
MODIFIED CANADIAN HIGH PRESSURE WILL BUILD IN AT THE SURFACE FROM
THE NW...ACCOMPANIED BY LOW LEVEL THICKNESSES THAT ARE 15-20 METERS
LOWER THAN TODAY. THIS SUPPORTS AWAY WITHIN A FEW DEGREES EITHER
SIDE OF 60. COASTAL COMMUNITIES THOUGH WILL BE SOME 5-7 DEGREES
COOLER.
THURSDAY...THE CLOSED LOW IN THE MID/UPPER TROPOSPHERE WILL MOVE
INTO THE EASTERN CANADIAN MARITIMES...WITH A NEGATIVELY TILTED
TROUGH SITUATES IN THE CENTRAL PLAINS. IN BETWEEN THESE TWO
FEATURES...THE LOCAL AREA WILL BE UNDERNEATH A HIGHLY AMPLIFIED
RIDGE FROM THE NORTHERN CARIBBEAN SEA TO SOUTH-CENTRAL CANADA.
SURFACE HIGH PRESSURE REMAINS IN CONTROL...BUT BEGINS TO WEAKEN AS
THE SOUTHERN PORTION OF IT SLIDES EAST INTO THE ATLANTIC. AN ONSHORE
RETURN FLOW WITHIN THE COUNTERCLOCKWISE PATTERN AROUND THE HIGH WILL
BRING WITH A SMALL INFLUX OF ATLANTIC MOISTURE...BUT NOT ENOUGH FOR
ANYTHING MORE THAN PATCHY STRATOCUMULUS CLOUDINESS. LOW LEVEL
THICKNESS AND 850 MB TEMPS ARE ON THE RISE...SO A WARMER DAY IS IN
STORE AWAY FROM THE MUCH COOLER COASTLINE...UNLESS JET STREAM CIRRUS
ARE THICKER THAN CURRENTLY ANTICIPATED.
FRIDAY...A SHORT WAVE LIFTING THROUGH THE NORTHERN PLAINS AND UPPER
MS VALLEY...WILL TAKE IT/S SURFACE LOW ALONG WITH IT AS THEY MOVE
NORTH AND NE. EXTENDING SE FROM THE LOW WILL BE A TRIPLE POINT
OCCLUSION IN THE TENNESSEE VALLEY OR IN ALABAMA...A TRAILING COLD
FRONT TO NEAR NEW ORLEANS...AND WARM FRONTOGENESIS OVER OR NEAR THE
LOCAL AREA. NORTH OF THE DEVELOPING WARM FRONT WE WILL BE FORMATION
OF A HIGH PRESSURE WEDGE...WITHIN THE COOL AIR DAMMING EAST OF THE
APPALACHIAN CHAIN. WITH THE GULF AND ATLANTIC OPENED UP WITHIN THE
FIRST 8-10K FEET...CONSIDERABLE MOISTURE WILL SPREAD ACROSS THE SE.
OVER-RUNNING RAINS WILL DEVELOP AS ISENTROPIC UPGLIDE BLOSSOMS AND
PWATS WILL CLIMB TO NEAR 2 STANDARD DEVIATIONS ABOVE NORMAL. RAIN
COVERAGE WILL INCREASE...AND DEPENDING UPON WHERE THE WARM FRONT
ALIGNS ITSELF WE MAY HAVE A SMALL RISK OF THUNDER. RAIN CHANCES WILL
BE HIGHEST OVER THE NW HALF...IN THE RANGE OF 50-60 PERCENT...AND
LOWEST SE PORTION...IN THE RANGE OF 20-30 PERCENT. THE TEMP FORECAST
WILL BE PROBLEMATIC...BUT PRESENT INDICATIONS ARE THAT WITH SOME
SORT OF WEDGE IN PLACE THAT NW SECTIONS WILL STRUGGLE TO GET OUT OF
THE 50S...BUT OUR EXTREME SOUTHERN ZONES MIGHT CLIMB NEAR 70.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
A VERY COMPLEX AND HUGE STORM SYSTEM WILL BE IMPACTING THE EASTERN
HALF OF THE NATION LATE IN THE WEEK...WITH A VERTICALLY STACKED LOW
OVER THE UPPER MIDWEST REGION INTO THE FIRST PART OF THE WEEKEND.
CLOSER TO HOME...AN ELONGATED AND NEARLY STATIONARY FRONT WILL
LINGER OVER OR NEAR THE FORECAST REGION INTO AT LEAST SATURDAY.
VARIOUS SHORT WAVES WITHIN AN ACTIVE SOUTHERN BRANCH OF THE JET
STREAM WILL PERIODICALLY PROGRESS THROUGH THE REGION...CAUSING THE
NEARBY FRONT TO OSCILLATE A LITTLE NORTH AND SOUTH AT TIMES FRIDAY
NIGHT THROUGH SATURDAY NIGHT. WHEN YOU THROW IN A 120-130 KT UPPER
LEVEL JET TO PROVIDE ADDITIONAL FORCING FOR ASCENT...AND PWATS THAT
ARE 2-3 STANDARD DEVIATIONS ABOVE NORMAL...A WET LATE WEEK IS IN
STORE FOR THE ENTIRE FORECAST AREA. RAINFALL TOTALS OF SEVERAL
INCHES MAY OCCUR IN MANY LOCALES...ALTHOUGH DUE TO THE SHOWERY
NATURE OF THE ACTIVITY...ACCUMULATIONS COULD VARY GREATLY FROM ONE
PLACE TO ANOTHER. THE WEDGE SHOWS INDICATIONS OF BREAKING DOWN BY
EARLY SATURDAY...WHICH MAY ALLOW FOR MANY AREAS TO MOVE INTO THE
WARM SECTOR. IF THIS WERE TO OCCUR THEN OUR RISK FOR T-STORMS AND
MAYBE EVEN MARGINALLY SEVERE WEATHER WILL INCREASE. OUR TEMP
FORECAST AGAIN WILL BE A CHALLENGE...SINCE ANY SLIGHT DEVIATION IN
THE FRONTAL POSITION WILL SPELL SIGNIFICANT CHANGES IN OUR LATEST
FORECAST.
AT SOME POINT EARLY NEXT WEEK THERE WILL BE A SOUTHERN STREAM SHORT
WAVE KICKER THAT FINALLY FORCES THE STALLED OUT FRONTAL SYSTEM TO
EXIT THE REGION. AS HIGH PRESSURE BUILDS FROM THE OHIO AND TENNESSEE
VALLEYS WE/LL FINALLY DRY THINGS OUT. THIS MIGHT ONLY BE TEMPORARY
THOUGH...AS THERE MIGHT BE YET ANOTHER RAINMAKER LATE IN THE
FORECAST PERIOD.
&&
.AVIATION /09Z TUESDAY THROUGH SATURDAY/...
CONDITIONS ARE EXPECTED TO REMAIN PRIMARILY VFR THROUGH 06Z
WEDNESDAY. THE MAIN FORECAST PROBLEM FOR THE NEXT 24 HOURS
REVOLVES AROUND THE APPROACHING COLD FRONT. MAY SEE SOME SCATTERED
STRATOCUMULUS THIS MORNING THROUGH SUNRISE FROM OFF THE NEARBY
MARINE AREAS BUT THIS IS EXPECTED TO REMAIN SCATTERED AT WORST. SW
WINDS WILL BEGIN TO GUST IN THE MID MORNING AND WILL GENERALLY TOP
OUT IN THE 22-24 KT RANGE THROUGH THE AFTERNOON. THE COLD FRONT
AND ASSOCIATED PRECIP WILL MOVE IN DURING THE EARLY AFTERNOON AND
I HAVE KEPT THE 19Z TIMING FROM THE PREVIOUS FORECAST AS IT STILL
LOOKS GOOD. THERE MAY BE BRIEF MVFR LEVEL CONDITIONS WITHIN THE
BAND OF SHOWERS ALONG THE FRONT THIS AFTERNOON...BUT THE
LIKELIHOOD OF EXTENDED PERIODS IS LOW ENOUGH TO KEEP OUT OF THE
FORECAST FOR NOW. THE FRONT AND ASSOCIATED PRECIP WILL PUSH
OFFSHORE IN THE EVENING FOLLOWED BY MORE WESTERLY WINDS AND
CLEARING SKIES.
EXTENDED AVIATION OUTLOOK...PERIODIC FLIGHT RESTRICTIONS ARE LIKELY
IN SHRA AND POSSIBLY EVEN ISOLATED TSRA FRIDAY THROUGH SATURDAY...AS
A FRONTAL SYSTEM IMPACTS THE AIRFIELDS. OTHERWISE...VFR CONDITIONS
WILL PREVAIL.
&&
.MARINE...
TODAY AND TONIGHT...A COLD FRONT WILL APPROACH FROM THE WEST
RESULTING IN A SURGE OF SW FLOW ACROSS THE LOCAL WATERS. ONGOING
SMALL CRAFT ADVISORIES LOOK WELL PLACED...THOUGH I DID ADD ONE TO
THE CHARLESTON HARBOR. AROUND MID MORNING WINDS SHOULD PICK UP AND
FREQUENT 25 KT GUSTS WILL OCCUR OVER THE HARBOR AND AROUND THE
ADJACENT SHORELINE. WINDS WILL BE STRONGEST OVER THE WATERS THROUGH
THE AFTERNOON...WITH A BIT OF A LULL EXPECTED IMMEDIATELY BEHIND THE
FRONT. WINDS WILL THEN PICK UP AGAIN LATE IN THE NW FLOW AND COLD
ADVECTION. IT STILL APPEARS THE OUTER GA WATERS WILL SEE ADVISORY
CONDITIONS LINGER THE LONGEST WHILE THE NEARSHORE WATERS DIMINISH
MORE INTO THE 15-20 KT RANGE LATE. SEAS ARE STILL EXPECTED TO BE 4-6
BEYOND 20 NM AND GENERALLY 3-5 FT WITHIN. HOWEVER...SOME 6 FT SEAS
MAY BE EXPERIENCED AROUND 20 NM OFF THE CHARLESTON COUNTY WATERS.
WEDNESDAY...ANY LINGERING SCA CONDITIONS ACROSS THE OUTER GA WATERS
EARLY ON WILL COME DOWN QUICKLY...AS COLD ADVECTION WANES AND THE
PRESSURE GRADIENT RELAXES WITH HIGH PRESSURE BUILDING FROM THE NW.
IN FACT THE PRESSURE PATTERN RELAXES ENOUGH THAT WEAK RESULTANT SEA
BREEZE CIRCULATIONS LOOK TO DEVELOP IN THE AFTERNOON.
THURSDAY...CONTINENTAL HIGH PRESSURE EARLY WILL SLIDE INTO THE
WESTERN ATLANTIC...AND VEERING WINDS WILL COMMENCE. WINDS AND SEAS
WILL BE ON THE RISE...BUT BELOW ANY HEADLINE CONDITIONS.
FRIDAY THROUGH SATURDAY...WARM FRONTOGENESIS WILL TAKE PLACE ACROSS
THE WATERS FRIDAY...AND THE FRONT WILL LINGER IN OR NEAR THE
IMMEDIATE AREA INTO SATURDAY. MOST OF THE WATERS WILL PROBABLY BE ON
THE SOUTH SIDE OF THE FRONT...BUT WITH A HIGH PRESSURE WEDGE TO BE
FOUND INLAND AND THE FRONT PERHAPS GETTING STUCK UP ON THE COOLER
SHELF WATERS...CHANGES MIGHT BE REQUIRED IN SUBSEQUENT COASTAL
WATERS FORECASTS. BUT SCA CONDITIONS ARE CERTAINLY POSSIBLE AT SOME
POINT LATE IN THE WEEK.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR AMZ330.
SMALL CRAFT ADVISORY UNTIL 1 AM EST WEDNESDAY FOR AMZ350-352.
SMALL CRAFT ADVISORY UNTIL 7 AM EST WEDNESDAY FOR AMZ374.
&&
$$
NEAR TERM...BSH
SHORT TERM...33
LONG TERM...33
AVIATION...BSH
MARINE...BSH/33
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1137 PM CST MON FEB 18 2013
...UPDATE TO AVIATION...
.DISCUSSION...
THE 20Z WATER VAPOR IMAGERY SHOWS THE UPPER TROUGH AXIS OVER
EASTERN KS MOVING EAST...WHILE ANOTHER UPPER LOW APPROACHED THE
PACIFIC NORTHWEST. AT THE SURFACE...A COLD FRONT HAS MOVES INTO
EASTERN OK AND WESTERN MO WITH COOLER AND DRIER AIR ADVECTING INTO
THE FORECAST AREA.
FOR TONIGHT...PRECIP SHOULD BE WELL OFF TO THE EAST WITH UPPER LEVEL
SUBSIDENCE INCREASING AS DRY AIR FILLS IN FROM THE NORTHWEST. MODELS
KEEP SOMEWHAT OF A PRESSURE GRADIENT OVER NORTHEAST KS AS SURFACE
RIDGING BUILD SOUTH THROUGH THE NORTHERN PLAINS. THIS SHOULD HELP
KEEP TEMPS FROM BOTTOMING OUT. ANOTHER CONCERN FOR OVERNIGHT LOWS IS
THE RAP PROG OF A STRATUS DECK REMAINING OVER NORTHEAST KS THROUGH
THE NIGHT. NONE OF THE OTHER MODELS SEEM TO AGREE WITH THIS AND
SATELLITE SHOWS A BROKEN STRATOCU FIELD ACROSS EASTERN NEB.
THEREFORE THINK THE RAP IS A BIT OVERDONE WITH THE CLOUDS...WHICH
ARE LIKELY A FUNCTION OF STEEP LOW LEVEL LAPSE RATES AND
INSTABILITY. ONCE THE BOUNDARY LAYER COOLS...THOSE LAPSE RATES
SHOULD RELAX AND THE STRATOCU FIELD DIMINISH. THINK LOWS WILL BE IN
THE UPPER TEENS TO LOWER 20S. SHORTWAVE RIDGING SHOULD DEVELOP FOR
TUESDAY WITH RIDGING AT THE SURFACE BUILDING IN. SO THE FORECAST IS
DRY WITH A COOL AND SUNNY DAY EXPECTED. COLD AIR ADVECTION FROM THE
NORTH SHOULD HOLD TEMPS IN THE 30S.
WOLTERS
CONFIDENCE IN A STRONG WINTER STORM IMPACTING THE AREA FOR THE MID
WEEK REMAINS ON TRACK. THE MODELS CONTINUE TO SHOW VERY LITTLE LARGE
SCALE VARIANCE...WITH THE MAIN NOTABLE ALTERATIONS BEING A SLIGHTLY
SLOWER TREND WITH THE UPPER TROF AND FARTHER SOUTH PLACEMENT OF THE
SURFACE LOW. THE SURFACE LOW IN FACT FILLS RATHER QUICKLY THURSDAY
AND STRONG ZONAL FLOW ALOFT DEVELOPS A SECONDARY LOW IN NORTHEAST
NEW MEXICO ON MANY RUNS. LARGE SCALE LIFT INCREASES FROM WEDNESDAY
AFTERNOON INTO THURSDAY MORNING VIA ISENTROPIC LIFT THEN Q-G
FORCING...WITH THE MAIN DRIVING FORCE FOR THE NEGATIVE TILT TO THE
UPPER TROF AXIS SEEN AS A DEEP POTENTIAL VORTICITY ANOMALY AROUND
50N AND 150W AT 18Z. PRECIPITABLE WATER VALUES DRAWN NORTH REMAIN
NEAR THE TWO STANDARD DEVIATION ABOVE NORMAL MARK WITH CONDITIONAL
SYMMETRIC TO UPRIGHT INSTABILITY IN THE UPPER LEVELS. THE DETAILS
REMAIN THE MAIN ISSUE AND WILL LIKELY CONTINUE TO BE THE MAIN
TROUBLE SPOT UNTIL THE EVENTS ONSET. THESE INCLUDE HOW COOL AND DRY
THE NEAR-SURFACE LAYER WILL BE...HOW FAST THE ISENTROPIC LIFT WILL
SATURATE THE COLUMN...HOW WARM AND FAR NORTH WILL THE WARM NOSE
AROUND 7000 FEET BE....AND HOW AND WHERE WILL LONG WILL ICE CRYSTALS
REMAIN IN THE CLOUD ALOFT. IN TERMS OF TEMPERATURES...THE SLIGHTLY
COOLER IDEA CONTINUES TO BE THE THEME...AND WITH THE FARTHER SOUTH
IDEA ALSO...DID TREND PRECIPITATION TYPES SOUTH A BIT. WIND SPEEDS
WILL BE CONSIDERABLE...BUT THE FILLING LOW SHOULD KEEP SPEEDS IN
CHECK A BIT...AND THE EXPECTED WET NATURE OF THE SNOW WOULD NOT
SUPPORT HIGH-END BLOWING AND DRIFTING. WITH SUCH PERSISTENT AND
CONSISTENT SOLUTIONS SEEN WITH THIS SYSTEM...EVEN AT THIS
RANGE...CONFIDENCE IS HIGH ENOUGH FOR MUCH OF THE AREA TO SEE
MODERATE TO HEAVY ACCUMULATIONS FOR A WATCH TO BE ISSUED AT THIS
RANGE.
MUCH MORE TRANQUIL CONDITIONS ARE EXPECTED FOR THE END OF THE
WEEK...WITH THE NEXT MORE SIGNIFICANT TROF COMING IN THE LATE PERIOD
OF THE FORECAST.
65
&&
.AVIATION...
EXPECT VFR CONDITIONS FOR THE NEXT 24 HOURS.
GARGAN
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY
AFTERNOON FOR KSZ008>012-020>024-026-034>040-054>056-058-059.
&&
$$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
931 PM MST MON FEB 18 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 302 PM MST MON FEB 18 2013
LATEST WV IMAGERY AND RUC H5 ANALYSIS SHOW ACTIVE PATTERN IN PLACE
ACROSS THE US WITH SEVERAL AMPLIFIED TROUGHS AND RIDGES. OVER THE
CENTRAL US A TROUGH CURRENTLY EXTENDS ACROSS THE NORTHERN PLAINS TO
NORTHERN TEXAS WITH A RIDGE UPSTREAM CENTERED OVER THE GREAT BASIN.
NW FLOW IS IN PLACE BETWEEN THESE FEATURES OVER OUR CWA...WITH
SUBSIDENCE CURRENTLY OVERHEAD AND A WEAK VORT MAX/EMBEDDED SHORTWAVE
TROUGH UPSTREAM OVER THE NEBRASKA PANHANDLE. AT THE SURFACE HIGH
PRESSURE IS BEGINNING TO BUILD OVER WESTERN KS WITH SURFACE GRADIENT
WEAKENING FROM THE WEST TO THE EAST...WHICH IS ALLOWING THE
STRONGEST WINDS TO DECREASE WELL BELOW ADVISORY CRITERIA.
THE WEAK TROUGH OVER THE NE PANHANDLE WILL QUICKLY PASS NORTH THIS
AFTERNOON AND EVENING WITH WEAK FORCING AND SOME MID LEVEL MOISTURE
MOVING ACROSS THE NORTHERN PART OF THE CWA. UPSTREAM RADARS ARE
SHOWING LIGHT REFLECTIVITIES...WHICH MATCH WHERE LATEST RUC PLACES
LIGHT QPF THROUGH THE AFTERNOON/EARLY EVENING HOURS. SURFACE TD
DEPRESSIONS ARE VERY LARGE...AND THIS LIKELY EXTENDS TO ABOUT 850MB
OR AROUND 8KFT BASED ON LATEST RUC SOUNDINGS. WITH LOW LEVELS THIS
DRY IT IS HARD FOR ME TO IMAGINE MUCH OF ANYTHING REACHING THE
SURFACE...THOUGH I COULDNT RULE OUT A FEW SPRINKLES OR FLURRIES
THROUGH ABOUT 1Z ACROSS THE NORTH.
H5 RIDGE WILL BUILD BACK OVER THE CWA TONIGHT AND TUESDAY WITH LARGE
SCALE SUBSIDENCE AND A VERY DRY AIRMASS EXPECTED TO BE IN PLACE.
THERE SHOULD BE SOME MODERATION OF THE AIR MASS IN PLACE BY TUESDAY
AFTERNOON WITH WAA AND GUSTY SOUTH WINDS DEVELOPING IN RESPONSE TO
LEE TROUGH DEEPENING OVER EASTERN COLORADO. I AM CURRENTLY EXPECTING
TEMPS IN NEAR 50F IN THE WEST TO MID 40S IN THE EAST...HOWEVER I
WOULDNT BE SURPRISED IF WE ARE A LITTLE WARMER THAN THIS.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 302 PM MST MON FEB 18 2013
WINTER STORM WATCH FROM WEDNESDAY THROUGH THURSDAY.
FORECAST FOCUS IS ON THE WINTER STORM EXPECTED TO IMPACT THE
FORECAST AREA ON WEDNESDAY AND THURSDAY.
CONFIDENCE IS HIGH IN THIS STORM OCCURRING OVER THE
REGION...ALTHOUGH DETAILS REMAIN TO BE SORTED OUT OVER THE NEXT
COUPLE OF DAYS AS THE STORM MOVES INTO THE WEST COAST AND BEGINS
TRACKING ACROSS THE FAR SOUTHWEST UNITED STATES. MAIN CONCERNS
WITH THIS STORM ARE THE EVENTUAL TRACK OF THE LOW CENTER AND THE
RESULTING AMOUNT OF COLD AIR IN PLACE OVER THE FORECAST AREA AND
EVENTUAL CHANGE-OVER TIME TO ALL SNOW. DEPENDING UPON THAT TRACK
AND TIMING...AREAS OF FREEZING PRECIPITATION AND RESULTING
SNOWFALL AMOUNTS COULD VARY GREATLY FROM WHAT IS CURRENTLY IN THE
FORECAST. HOWEVER...EVEN WITH THE POTENTIAL VARIATION IN THOSE
ELEMENTS...CONFIDENCE WAS HIGH ENOUGH IN THIS BEING A SIGNIFICANT
ENOUGH STORM TO WARRANT PUTTING OUT A WINTER STORM WATCH DUE TO
POSSIBLE AREAS OF FREEZING RAIN AND DRIZZLE COMBINED WITH MODERATE
TO HEAVY SNOW AND AREAS OF BLOWING SNOW.
FOLLOWING THIS EVENT...COLDER TEMPERATURES SHOULD REMAIN OVER THE
AREA WHERE HEAVIEST SNOWFALLS HAVE OCCURRED WITH TEMPERATURES
GRADUALLY WARMING THROUGH THE REMAINDER OF THE WEEK AND INTO THE
BEGINNING OF NEXT WEEK.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 930 PM MST MON FEB 18 2013
VFR EXPECTED THROUGH THE PERIOD AT KGLD AND KMCK. VRB06 WINDS
EXPECTED AT BOTH SITES THROUGH 17Z OR SO TUESDAY MORNING. FOR
KGLD WIND GUSTS 25-30KTS WILL BE COMMON AFTER 17Z WHILE AT KMCK
EXPECT WINDS 10-15KTS WITH A FEW HIGHER GUSTS. THESE WINDS WILL
CONTINUE AND MAY INCREASE A BIT AFTER 02Z OR SO AS LOW LEVEL JET
STRENGTHENS AND PRESSURE GRADIENT INCREASES AHEAD OF APPROACHING
UPPER TROUGH. SOME CIRRUS TO MOVE OVER FROM THE SOUTHWEST EARLY
TUESDAY MORNING WITH SOME AFTERNOON CU POSSIBLE AS WELL.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...WINTER STORM WATCH FROM WEDNESDAY MORNING THROUGH THURSDAY
AFTERNOON FOR KSZ001>004-013>016-027>029-041-042.
CO...WINTER STORM WATCH FROM WEDNESDAY MORNING THROUGH THURSDAY
AFTERNOON FOR COZ090>092.
NE...WINTER STORM WATCH FROM WEDNESDAY MORNING THROUGH THURSDAY
AFTERNOON FOR NEZ079>081.
&&
$$
SHORT TERM...DR
LONG TERM...LOCKHART
AVIATION...99
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
652 PM EST WED FEB 20 2013
...Updated Aviation Discussion...
.Short Term (Tonight through Thursday Night)...
Issued at 300 PM EST Wed Feb 20 2013
...A Brief Period of Wintry Weather Coming North of the I-64
Corridor...
What a mess as far as dealing with winter weather, as our next
system will bring it`s winter weather transition zone right across
our forecast area Thursday afternoon to late Thursday night.
Until then, the main forecast issue tonight will be cloud cover.
Shield of mid/high clouds moving in now is not forecast to last all
night. The RAP is advertising additional lower level clouds moving
in from the north, a low stratus, which right now is associated with
the flow coming off Lake Michigan. Will lean toward the rest of the
guidance, which keeps us clearer, overnight, except over the far
north. Then mid clouds should increase again as the system mentioned
above starts to influence our weather.
The atmosphere will saturate from above as an occluded front
approaches from the west. Deep isentropic ascent ahead of this front
will allow precipitation to start west of the I-65 corridor by late
afternoon. With the onset of this precip, expect temperatures to
drop a couple of degrees, which will allow for a mix of sleet/snow
across the north and cold rain down south. By 00Z, warm air aloft
will help to melt the deep freezing layer, allowing for the chance
for freezing rain across the north. As the night goes on, the warm
air will deepen and expect a transition over the just rain areawide
by around 09Z.
Forecast uncertainty remains high enough to keep us from issuing an
advisory. Went under guidance for temperatures at the surface and
aloft. If model forecast temperatures are true, and it should be
noted that our forecast errors for this forecast time period average
2-3 degrees, than much more of the area will be mostly rain. Based
on this uncertainty, have decided to issue just a special weather
statement on the chance for winter weather and hold off on issuing a
third-period advisory.
.Long Term (Friday through Tuesday Night)...
Issued at 326 PM EST Wed Feb 20 2013
The beginning of the long term period will feature a strong
shortwave pushing north through the Northern Plains. In its wake, a
trough will amplify across the central CONUS this weekend which will
work into the Ohio Valley. Another upper ridge will amplify across
the Ohio Valley ahead of the next system set to affect the region
early next week.
A warm front will be lifting north through the region early Friday
morning, with the associated synoptic forcing/isentropic ascent
lifting north into Ohio. Therefore, precipitation will taper off
from southwest to northeast through the day as a dry slot works
into the region. Temperatures on Friday will be rather warm, as the
surface cold front will remain well off to the west, allowing for
southwesterly winds to aid in a quick warmup in the wake of the
morning precipitation.
The associated cold front will finally push through the region late
Friday into early Saturday. Another shortwave will swing through
the mean trough Saturday morning, which will induce secondary
surface low development across TN/GA. As this wave rides along the
departing cold front, it will act to stall its progress. In fact,
the 12Z suite of guidance is suggesting there may be enough moisture
kicked back into the region to produce some additional precipitation
across the Cumberland area as the shortwave and surface low pass
by. If this moisture were to get far enough north into the cooler
air, then some light freezing rain/drizzle could creep into the
northern Bluegrass region Saturday morning. However, this
probability looks rather low at this point and will leave
precipitation as all rain for now and confined to the far
east/southeast portions of the CWA.
A ridge will build across the region late Saturday through Monday,
providing calm and dry weather conditions. Temperatures will warm
each day through the weekend, as temperatures in the lower 40s on
Saturday warm into the middle 50s by Monday.
Another strong upper level wave will eject out into the Central and
Northern Plains on Monday. This system looks very similar to the
Thursday/Friday system, spreading a slug of precipitation north in
association with a wave of isentropic ascent atop the surface warm
front. This time, however, the cooler air will not be in place
ahead of the approaching warm front, so any and all precipitation
will remain rain. The surface cold front will push through late
Monday night into Tuesday morning, dropping temperatures back into
the upper 40s Tuesday afternoon.
The 20/12Z GFS advertises the surface low tracking across Indiana
and Ohio, which would bring some wrap-around precipitation to
portions of southern Indiana and northern Kentucky Tuesday into
early Wednesday. However, with a strong upper ridge in place, this
system will struggle dropping southeast like the GFS suggests.
Therefore, will favor the ECMWF and GFS ensembles, lifting the
surface low and its associated wrap-around precipitation further
north, thus keeping the forecast dry through the remainder of the
long term period.
&&
.Aviation (00Z TAF Issuance)...
Issued at 652 PM EST Wed Feb 20 2013
The interesting weather is just out of the 24 hour window this
period. After some thinning cirrus moving over SDF and LEX now
exits to the northeast, a weak ridge builds over the lower Ohio
Valley between the exit of an upper Low over the eastern Great Lakes
and the northeast advance of another upper Low set to race northeast
out of the southern Rockies across the Plains states tomorrow.
Guidance time cross sections hint at temperatures dipping close
enough to dew points overnight to result in some brief MVFR vsbys,
after 09z but winds should remain up just enough to keep this from
happening so have not introduced a TEMPO group in but will keep an
eye on trends this evening.
For the extended section of the SDF TAF...could see a mixture of
liquid and frozen precip at onset, but this far out will just
mention -SHSN.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
KY...NONE.
$$
Short Term.......RJS
Long Term........KJD
Aviation.........JBS
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
413 PM EST TUE FEB 19 2013
.SYNOPSIS...
SCATTERED SNOW SHOWERS WILL BE POSSIBLE THIS EVENING THROUGH
WEDNESDAY AS AN UPPER LEVEL LOW PASSES NORTH OF THE AREA AND AN
ARCTIC AIR MASS PUSHES INTO THE AREA IN THE WAKE OF A COLD FRONT.
HIGH PRESSURE WILL MOVE ACROSS THE AREA THURSDAY BEFORE THE NEXT
FRONTAL SYSTEM BRINGS THE POTENTIAL FOR A WINTRY MIX THURSDAY NIGHT
INTO FRIDAY.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
THE LATEST RAP MID-LEVEL ANALYSIS INDICATES AN CLOSED LOW CENTERED
OVER NORTHERN MICHIGAN WITH A BROAD CYCLONIC FLOW AROUND THIS
FEATURE EXTENDING INTO THE OHIO VALLEY. A VORT LOBE IS SWINGING
ACROSS WESTERN PA WITH THE TROUGH SOUTH OF THE LOW. IN
ADDITION...A 500MB VORT MAX IS PUSHING INTO NW OHIO. THIS FEATURE
IS PROVIDING FORCING FOR SCATTERED SNOW SHOWERS MOVING INTO THE
UPPER OHIO VALLEY. AT THE SURFACE...A COLD FRONT HAS PUSHED EAST
OF THE FORECAST AREA WITH CAA ONGOING IN A WEST-SOUTHWESTERLY
FLOW.
TONIGHT...GFS/NAM/ECMWF AGREE THAT THE CLOSED LOW WILL MOVE FROM
THE NORTHERN GREAT LAKES INTO UPSTATE NY OVERNIGHT. THE
AFOREMENTIONED VORT MAX WILL SHIFT INTO NRN PA OVERNIGHT WITH A
WESTERLY 1000-500MB MEAN LAYER WIND BECOMING MORE WEST-
NORTHWESTERLY BY 12Z WEDNESDAY. WITH THIS IN MIND...HAVE FORECAST
THE CHANCE OF SNOW SHOWERS ACROSS THE LOWLANDS WITH LIKELY POPS
ACROSS THE RIDGES AND I-80 CORRIDOR. HIRES MODELS (1KM ECM/HRW
WRF-NMM AND NAM NESTED) INDICATE SCATTERED SNOW SHOWERS WITH THE
SPC STORM-SCALE ENSEMBLE OF OPPORTUNITY (SSE) PICKING UP ON
UPSLOPING COMPONENT WITH MORE NUMEROUS SNOW SHOWERS ACROSS THE
RIDGES. WITH THIS IN MIND...SNOWFALL FORECAST TONIGHT CONSISTS OF
1 TO 2 INCHES FOR THE EASTERN RIDGES AND THE I-80 CORRIDOR AND AN
INCH OR LESS ELSEWHERE. FOR TEMPS...A MAV/MET BLEND WAS USED WITH
LOWS RANGING FROM THE MID TO UPPER TEENS ACROSS THE AREA.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/...
A MODEL CONSENSUS INDICATES THAT THE UPPER LEVEL CYCLONE WILL PUSH
FURTHER EAST INTO THE NORTHEAST ON WEDNESDAY. THIS WILL ALLOW FOR THE
LOW-LEVEL FLOW TO VEER SLIGHTLY MORE...WITH A NORTHWESTERLY PREVAILING
WIND ON WEDNESDAY. GFS/NAM/CANADIAN INDICATE ANOTHER VORT MAX
CLIPPING LOCATIONS NORTHEAST OF PITTSBURGH DURING THE DAY...WITH
BETTER CHC FOR SNOW SHOWERS THERE. OTHERWISE...SNOW SHOWERS CHANCES
WILL BE DIMINISHING SOUTH AND WEST OF PITTSBURGH...WITH A DRY
FORECAST IN EASTERN OHIO BY 18Z. THUS...AN ADDITIONAL HALF OF AN
INCH TO AN INCH IS FORECAST NORTHEAST OF KPIT AND ACROSS THE RIDGES.
HIGHS ON WEDNESDAY WILL BE 10 TO 15 DEGREES BELOW NORMAL IN THE CORE
OF THE ARCTIC AIR MASS.
MOISTURE ASSOCIATED WITH THE UPPER LOW WILL FINALLY ADVECT NORTHEAST
OF THE AREA ON WEDNESDAY NIGHT AS A MID-LEVEL RIDGE AND HIGH
PRESSURE WILL BEGIN TO APPROACH FROM THE WEST. THIS WILL ALLOW FOR
ANY LINGERING SNOW SHOWERS TO COME TO AN END. A DRY FORECAST WILL
CONTINUE THROUGH THE DAY ON THURSDAY AS SURFACE HIGH PRESSURE
EXTENDS INTO THE AREA. TEMPS WILL BE AROUND 10 DEGREES BELOW NORMAL.
UNCERTAINTY AND MODEL INCONSISTENCY COMES INTO THE FORECAST FOR
THURSDAY NIGHT INTO FRIDAY. MODELS DO AGREE ON A STRONG UPPER LEVEL
VORTEX MOVING FROM THE CENTRAL PLAINS INTO THE UPPER MIDWEST DURING
THIS PERIOD. HOWEVER...SOLUTIONS DIFFER ON RESOLVING THE THERMAL
PROFILE OF A FRONTAL BOUNDARY PUSHING INTO THE OHIO VALLEY AHEAD OF
THE LOW. FORECAST CONSISTS OF A CANADIAN/ECMWF BLEND...WITH A TENTH
TO QUARTER OF AN INCH OF PRECIP REACHING THE AREA ON FRIDAY.
SOUNDINGS...1000-500MB/1000-850MB CRITICAL THICKNESS VALUES...AND
850MB TEMPS INDICATE THAT ONCE AGAIN THE UPPER OHIO VALLEY WILL BE
RIGHT ALONG THE LINE OF A WINTRY MIX OF PRECIPITATION. AT THIS
TIME...HAVE INCLUDED A WINTRY MIX OF SNOW...SLEET...AND FREEZING
RAIN ACROSS THE AREA WITH LIGHT ICE ACCUMULATION POSSIBLY LEADING
TO AN ADVISORY EVENT.
TEMPS THURSDAY NIGHT AND FRIDAY WILL BE A FEW DEGREES ABOVE
NORMAL...ALTHOUGH DEPENDING ON THE PLACEMENT OF THE BOUNDARY AND
STRENGTH OF WAA...THIS COULD IMPACT TEMP FORECAST FOR THIS
PERIOD.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
A LOW PRESSURE CENTER MOVING SLOWLY THROUGH THE GREAT LAKES WILL
BRING A CHANCE OF RAIN AND SNOW SHOWERS FOR FRIDAY NIGHT INTO
SATURDAY NIGHT. HIGH PRESSURE WILL PROVIDE DRY WEATHER FOR SUNDAY
THROUGH MONDAY WITH TEMPERATURES A BIT ABOVE NORMAL. A COLD FRONT
PUSHING TOWARD THE DISTRICT WILL BRING A CHANCE OF SHOWERS MONDAY
NIGHT INTO TUESDAY.
&&
.AVIATION /21Z TUESDAY THROUGH SUNDAY/...
WIDESPREAD MVFR CEILINGS CAN BE EXPECTED THIS EVENING ALONG WITH A
FEW SNOW FLURRIES. FREQUENT SFC WND GUSTS OF 20 TO 25 KT ARE
ANTICIPATED THIS EVENING...BUT WILL DIMINISH AFTER MIDNIGHT. STRATOCU
CEILINGS WILL PERSIST TONIGHT ALONG WITH OCCASIONAL RESTRICTIONS IN
SNOW SHOWERS.
.OUTLOOK.../WEDNESDAY THROUGH SUNDAY/...
LINGERING RESTRICTIONS ARE ANTICIPATED THROUGH WEDNESDAY IN THE
COLD NORTHWEST FLOW BEHIND THE FRONT. VFR IS ANTICIPATED WITH THU
HIGH PRES. RESTRICTIONS ARE POSSIBLE AGAIN ON FRIDAY AND SATURDAY
WITH THE CROSSING OF ANOTHER TROF. VFR WEATHER CAN BE EXPECTED
SUNDAY WITH HIGH PRESSURE.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
340 PM EST TUE FEB 19 2013
.SYNOPSIS...
A COLD FRONT AND ASSOCIATED PRECIPITATION WILL MOVE OFF THE MIDDLE
ATLANTIC COAST LATER THIS EVENING. GUSTY WINDS WILL FOLLOW WEDNESDAY
INTO WEDNESDAY NIGHT FOLLOWED BY HIGH PRESSURE BRIEFLY SETTLING OVER
THE REGION ON THURSDAY. A WAVE OF LOW PRESSURE WILL BRING A WINTRY
MIX TO THE MIDDLE ATLANTIC ON FRIDAY INTO THE FIRST PART OF THE
WEEKEND.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
MAIN AREA OF LIFT/RAIN WILL PROGRESS EASTWARD THROUGH CENTRAL AND
SOUTHERN MARYLAND THROUGH LATE AFTERNOON. COLD FRONT WAS APPROACHING
THE POTOMAC HIGHLANDS AT 19Z. THERE IS A THIN BAND OF PRECIPITATION
AHEAD OF IT THAT WILL AFFECT THE HIGHLANDS. HRRR AND WRF-ARW SUGGEST
THIS THIN BAND HOLDS TOGETHER EAST TOWARD THE BAY /AS RAIN/ AS THE
FRONT MOVES THROUGH. THUS HAVE CONTINUED POPS UNTIL THE FROPA.
COLD FRONTAL PASSAGE LOOKS TO OCCUR JUST BEFORE 00Z ACROSS THE
INTERSTATE 95 CORRIDOR. WINDS WILL SHIFT FROM SOUTH TO WEST...AND
MAY BECOME GUSTY. CLOUDS WILL HANG TOUGH PRIOR TO THE FROPA...BUT
EXPECT CLEARING TO OCCUR LATER THIS EVENING BEHIND THE FRONT.
UPSLOPE SNOW SHOWERS ARE EXPECTED TONIGHT BEHIND THE FRONT AS
WELL...BUT ACCUMULATIONS ON THE WESTERN SLOPES ARE EXPECTED TO BE ON
THE ORDER OF 1 TO 2 INCHES WHICH IS BELOW WINTER WEATHER ADVISORY
CRITERIA.
ENTIRE CWA WILL BE BLUSTERY OVERNIGHT...WITH THE RIDGES ON THE WINDY
SIDE. COULD GET CLOSE TO WIND ADVISORY CRITERIA ON THE RIDGE TOPS.
WILL CONTINUE HWO MENTION FOR 40 MPH GUSTS.
WEDNESDAY WILL BE A WINDY DAY ACROSS THE CWA...WITH GUSTS OF 35 MPH
AT TIMES AND HIGHER OVER THE RIDGE TOPS. EXPECT THE SUN TO RETURN
BUT DESPITE A DOWNSLOPING FLOW CHILLY AIR ALOFT WILL LIKELY BRING AT
LEAST SOME SCATTERED CLOUDS FOR THE AFTERNOON.
MAXIMA WILL BE COLDER AS WELL...10 OR MORE DEGREES BELOW CLIMO. THIS
IS CAPTURED WELL BY BIAS CORRECTED MAV/MET GUIDANCE.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY/...
WINDS WILL GRADUALLY DIMINISH WEDNESDAY NIGHT AS THE GRADIENT
RELAXES BETWEEN THE DEPARTING LOW AND BUILDING RIDGE. COLD
TEMPERATURES WILL FOLLOW FOR WEDNESDAY NIGHT WITH LOWS IN THE
LOWER TO MIDDLE 20S MOST SECTIONS EXCEPT LOWER TO MIDDLE TEENS
FURTHER NORTH AND WEST. BELOW NORMAL TEMPERATURES ARE EXPECTED
THURSDAY AFTERNOON AS READINGS STRUGGLE TO REACH THE 40 DEGREE
MARK IN MOST LOCALES.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
THE NEXT WEATHER MAKER WILL CROSS THE FOUR CORNERS REGION
WEDNESDAY NIGHT INTO THURSDAY WITH LOW PRESSURE EJECTING NORTHEAST
INTO THE GREAT LAKES BY FRIDAY. PRECIPITATION ASSOCIATED WITH THIS
FEATURE WILL DEVELOP OVER WESTERN SECTIONS EARLY FRIDAY MORNING
AND SPREAD EAST ACROSS THE REMAINDER OF THE FORECAST AREA FRIDAY
AFTERNOON. THE PRECIPITATION ASSOCIATED WITH THIS SYSTEM APPEARS TO
BE LIGHT AND DRIVEN BY WARM AIR ADVECTION PROCESSES ATOP A SHALLOW
COLD AIRMASS. OF CONCERN...MODELS CONTINUE TO SHOW A PERSISTENT
COLD AIR DAMMING WEDGE WITH A 1025-1030MB HIGH TO THE NORTH FOR
THE START OF THE EVENT. INITIALLY...PRECIPITATION WOULD FALL IN
THE FORM OF SNOW WITH SOME SLEET POSSIBLE. IT GETS A BIT
CHALLENGING LATER FRIDAY MORNING AND AFTERNOON AS WARM ADVECTION
CONTINUES AND THE COLD AIR BEGINS TO GET SCOURED TO THE NORTH.
MODELS TYPICALLY DO NOT HANDLE TIMING OF THIS SCENARIO TOO WELL
AND AM CONCERNED THAT MORE FROZEN PRECIPITATION COULD HANG AROUND
LONGER. EVENTUALLY THE WARMER AIR IS EXPECTED TO WIN OUT EAST OF THE
BLUE RIDGE WITH PRECIPITATION CHANGING TO RAIN FOR THE METRO AREAS
BUT COULD REMAIN SLEET/FREEZING RAIN WEST OF THE BLUE RIDGE AND OVER
NORTHERN MARYLAND NEAR THE MASON DIXON LINE. HAVE TRENDED
TEMPERATURES DOWN A COUPLE DEGREES FOR HIGHS. WILL HAVE TO WATCH
THIS SCENARIO CLOSELY.
PRECIPITATION COULD HOLD IN PLACE INTO SATURDAY OVER THE WESTERN
FIVE IN UPSLOPE REGIME AND OVER SOUTHERN AND CENTRAL MARYLAND AS
LOW PRESSURE DEVELOPS OVER THE CAROLINAS AND MOVES NORTHEAST AWAY
FROM THE FORECAST AREA LATER SATURDAY. 12Z ECMWF NOW TRACKS THIS
LOW A BIT FURTHER EAST WHICH PRESENTS LESS OF A THREAT TO OUR AREA.
WILL STILL HOLD ONTO CHANCE POPS FOR RAIN SATURDAY. TRANQUIL WEATHER
IS PROGGED TO RETURN TO THE REGION ON SUNDAY WITH A POSSIBLE
MODERATION IN TEMPERATURES IF LONGER RANGE PROGS BODE WELL FOR EARLY
NEXT WEEK.
&&
.AVIATION /20Z TUESDAY THROUGH SUNDAY/...
MVFR CONDITIONS...MAINLY FROM CIGS WITHIN RAIN...ARE EXPECTED TO
LINGER INTO LATE AFTERNOON ACROSS THE DC-BALT HUBS. CONDITIONS
SHOULD IMPROVE TO VFR THEREAFTER...PARTICULARLY WITH A FRONTAL
PASSAGE AROUND 23Z. THIS WILL INITIATE A WIND SHIFT FROM SOUTH TO
WEST. WINDS MAY BE GUSTY WITH THE FROPA AND BEHIND IT. GUSTY WINDS
EXPECTED TO CONTINUE INTO WEDNESDAY...BEING THE PRIMARY AVIATION
IMPACT.
GUSTY WINDS WILL SUBSIDE WEDNESDAY NIGHT BUT WILL BE BREEZY AGAIN
THURSDAY WITH SPEEDS GENERALLY IN THE 10 TO 15 KT RANGE WITH GUSTS
TO 20 KTS. VFR EXPECTED THURSDAY. WINTRY PRECIPITATION WILL BE
POSSIBLE AT THE TERMINALS FRIDAY INTO FRIDAY NIGHT WITH SUB-VFR
CONDITIONS POSSIBLE. RAIN POSSIBLE SATURDAY INTO SATURDAY NIGHT
BEFORE VFR RETURNS FOR SUNDAY.
&&
.MARINE...
COLD FRONT WILL MOVE ACROSS THE WATERS EARLY THIS EVENING. HAVE BEEN
EXPERIENCING MARGINAL SMALL CRAFT ADVISORY CONDITIONS IN SOUTHERLY
FLOW THIS AFTERNOON. WITH FRONTAL PASSAGE...WINDS WILL SHIFT TO THE
WEST AND BECOME MORE GUSTY /25 KT/. WINDS ON WEDNESDAY ARE THEN
EXPECTED TO TURN TO THE NORTHWEST. MODELS TEND TO UNDERFORECAST
SPEEDS IN NORTHWEST FLOW WITH ADVECTION...THEREFORE HAVE GONE ABOVE
GUIDANCE WHICH PLACES THE BAY/LOWER TIDAL POTOMAC INTO LOW END
GALES.
GUSTY WINDS WILL DIMINISH WEDNESDAY NIGHT BUT SMALL CRAFT
CONDITIONS MAY BE POSSIBLE AGAIN ON THURSDAY. WINTRY PRECIPITATION
COULD DEVELOP OVER THE WATERS REDUCING VISIBILITIES DURING FRIDAY
WITH RAIN EXPECTED FRIDAY NIGHT INTO SATURDAY. SMALL CRAFT CONDITIONS
MAY OCCUR OVER THE WEEKEND AS A COASTAL LOW MOVES BY TO THE
NORTHEAST.
&&
.TIDES/COASTAL FLOODING...
COLD FRONT MOVES THROUGH EARLY THIS EVENING. SOUTHERLY WINDS WILL
SHIFT TO THE WEST TONIGHT...THEN LIKELY TO THE NORTHWEST FOR
WEDNESDAY/WEDNESDAY NIGHT. EXPECT WATER LEVELS TO DRAMATICALLY DROP
TONIGHT...PERHAPS TO 1 TO 2 FEET BELOW ASTRONOMICAL PREDICTIONS FOR
WEDNESDAY.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 2 PM EST WEDNESDAY FOR
ANZ530>534- 537>543.
GALE WARNING FROM 2 PM WEDNESDAY TO MIDNIGHT EST WEDNESDAY
NIGHT FOR ANZ530>534-537>543.
SMALL CRAFT ADVISORY UNTIL MIDNIGHT EST WEDNESDAY NIGHT FOR
ANZ535-536.
&&
$$
SYNOPSIS...KRW
NEAR TERM...BPP
SHORT TERM...KRW
LONG TERM...KRW
AVIATION...BPP/KRW
MARINE...BPP/KRW
TIDES/COASTAL FLOODING...BPP
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
431 PM EST TUE FEB 19 2013
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 430 PM EST TUE FEB 19 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A NEG-TILT MID/UPPER LEVEL
TROUGH FROM HUDSON BAY THROUGH NW ONTARIO INTO WI/LOWER MI BEING
PROPELLED SLOWLY EAST BY A 110-120 KT 300-250 JET MOVG THROUGH THE
OHIO VALLEY TOWARD THE EASTERN LAKES IN THE BASE OF THE TROUGH.
THE BACK EDGE OF A WELL-DEFINED WARM CONVEYOR SHIELD EXTENDS BACK
INTO ERN LAKE SUPERIOR. MODERATE Q-VECT CONV COMBINED WITH NNW FLOW
ACROSS ERN LAKE SUPERIOR SUPPORTING WIND-PARALLEL LES BANDS OF
MODERATE TO HEAVY IN INTENSITY EAST OF MQT. TIGHT PRES GRADIENT ON
BACKSIDE OF 992 MB SFC LOW EAST OF LAKE SUPERIOR STILL MAINTAINING
HIGH GALE TO STORM FORCE WINDS OVER ERN HALF OF LAKE SUPERIOR.
STRONG WINDS AND MODERATE SNOW RESULTING IN BLIZZARD CONDITIONS OVER
THE KEWEENAW PENINSULA AND OVER ALGER COUNTY. STATE POLICE HAS
CLOSED M-28 BETWEEN HARVEY AND WETMORE DUE TO BLIZZARD CONDITIONS
AND IMPASSABLE ROAD CONDITIONS.
THE MODERATE 700-300 QVECTOR CONV AND DEEPER MOISTURE WILL LIFT
SLOWLY EAST WITH THE MOVEMENT OF SFC LOW TONIGHT. AS A RESULT LAKE
ENHANCED SNOW SHOWERS OVER ERN COUNTIES SHOULD SLOWLY
DIMINISH...ESPECIALLY OVERNIGHT INTO WEDNESDAY. DRIER AIR WORKING IN
OVER THE WRN PORTION OF LAKE SUPERIOR AS NOTED ON VIS SATELLITE HAS
GREATLY DIMINISHED LES OVER FAR WRN COUNTIES LATE THIS AFTERNOON.
THUS...HAVE DOWNGRADED WARNINGS TO WINTER WX ADVISORIES THIS EVENING
OVER GOGEBIC...ONTONAGON...BARAGA AND SRN HOUGHTON COUNTIES. WILL
CONTINUE BLIZZARD WARNINGS INTO THIS EVENING OVER THE KEWEENAW
PENINSULA AS WINDS GUSTING AOA 35 MPH WILL STILL CAUSE LOW
VISIBILITY AND TRAVEL DIFFICULTIES THERE. MARQUETTE COUNTY HAS SEEN
SNOW DIMINISH ACROSS MUCH OF THE AREA BUT LIGHT TO MODERATE LES
BANDS AND BLOWING SNOW...ESPECIALLY EAST OF MQT...WILL CONTINUE TO
CAUSE TRAVEL DIFFICULTIES INTO THE EVENING HRS SO KEPT WARNING GOING
FOR MQT COUNTY. CONTINUED DRYING FROM THE WEST SHOULD LEAD TO
IMPROVED CONDITIONS FOR MARQUETTE COUNTY WESTWARD LATE TONIGHT INTO
WEDNESDAY.
MOST PROLONGED HAZARDOUS CONDITIONS WILL BE FOR COUNTIES EAST OF MQT
WHERE WINDS GUSTING OVER 40 MPH AND MODERATE LES BANDS WILL
CONTINUE THE BLIZZARD TO NEAR BLIZZARD CONDITIONS THROUGH TONIGHT
AND POSSIBLY INTO WED MORNING. CONTINUED THE BLIZZARD WARNING FOR
ALGER COUNTY THROUGH MUCH OF WEDNESDAY DUE TO OCCASIONAL MODERATE
SNOW AND EXTREME BLOWING SNOW WITH STRONG NNW WINDS TO 35-40 MPH. AS
NOTED EARLIER...M-28 CLOSED BTWN HARVEY AND WETMORE DUE TO BLIZZARD
CONDITIONS. FAVORABLE SNOW GROWTH WITH DGZ WITHIN AREA OF BEST MODEL
OMEGA WILL ADD TO POOR VISIBILITY AND POTENTIAL FOR GREATER SNOWFALL
AMOUNTS TONIGHT INTO WED MORNING. MODEL AVG QPF ALONG WITH SLR FM
20-25/1 SHOULD YIELD 3-6 INCH SNOW AMOUNTS TONIGHT OVER ALGER AND
NRN SCHOOLCRAFT AND 2-5 INCHES OVER LUCE COUNTY AND SRN SCHOOLCRAFT.
DEEPER MOISTURE LEAVING THE AREA AND WEAKENING CYCLONIC NNW FLOW
WILL ALLOW LES TO GRADUALLY TAPER OFF BY WED AFTERNOON OVER ERN
COUNTIES WITH GENERALLY ADDITIONAL ACCUMS ON WED OF 2-4
INCHES.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 430 PM EST TUE FEB 19 2013
COMPARED TO WHAT WAS OCCURRING OUTSIDE TODAY...THE LONG TERM IS
GENERALLY QUIET THROUGH MUCH OF THE PERIOD.
LAKE EFFECT SNOW WILL BE SLOWLY DIMINISHING ON WEDNESDAY NIGHT AS
1040MB HIGH PRESSURE OVER NORTHERN ONTARIO CONTINUES TO PUSH A
SURFACE RIDGE OVER LAKE SUPERIOR. SUBSIDENCE ALOFT FROM THIS
HIGH WILL SLOWLY DROP THE INVERSION HEIGHTS OVER THE EASTERN
LAKE FROM AROUND 4KFT AT 00Z THURSDAY TO 2KFT AT 12Z. BUT...THERE
LOOKS TO BE ENOUGH MOISTURE SUB 900MB TO LEAD TO SOME LAKE EFFECT
SNOW IN THE NORTHERLY WIND LOCATIONS OF NORTH CENTRAL UPPER
MICHIGAN. NOT OVERLY IMPRESSED WITH THE THICKNESS OF THE CLOUD
LAYER...ONLY ABOUT 1-2KFT THICK...SO THERE MIGHT NOT BE MORE THAN
VERY LIGHT SNOW OR FLURRIES LATE WEDNESDAY NIGHT INTO THURSDAY
MORNING /MORE NORTHEAST WINDS THEN/ BEFORE THE DRIER AIR LOWERS THE
INVERSION AND SHOVES THE LINGERING CLOUDS TOWARDS THE SURFACE. AT
THAT POINT...IT WOULD LIKELY BE EITHER LOW CLOUDS OR MIX OUT FROM
DIURNAL MIXING INLAND.
THIS HIGH WILL REMAIN IN PLACE INTO THURSDAY NIGHT...AS A LOW
PRESSURE SYSTEM BEGINS TO EXIT THE CENTRAL PLAINS. MODELS NOT
SHOWING MUCH IN THE WAY OF STRENGTHENING OR WEAKENING AS THIS LOW
MOVES INTO THE GREAT LAKES ON FRIDAY AND THE UPPER GREAT LAKES ON
SATURDAY DUE TO IT BECOMING DETACHED FROM THE STRONGER SOUTHERN
STREAM JET. WITH IT PRECIPITATING ON IT/S WAY UP INTO THIS
AREA...BEING CUT OFF FROM THE GULF MOISTURE...AND RUNNING INTO DRY
AIR FROM THE CANADIAN HIGH...THE IDEA THE MODELS HAVE SHOWN FOR
SEVERAL DAYS OF THE SNOW DIMINISHING AS IT MOVES INTO THE GREAT
LAKES AREA SEEMS REASONABLE. WOULD EXPECT THE LIGHT SNOW TO MOVE
INTO THE AREA ON FRIDAY MORNING AND CONTINUE INTO THE DAY ON
SATURDAY. TOTAL QPF THROUGH THE 36 HOUR PERIOD LOOKS TO BE AROUND
0.25-0.4 INCH. ESTIMATED SNOW RATIOS AROUND 15 TO 1 AT THIS POINT
WOULD LEAD TO 4-6 INCHES OF SNOW OVER MUCH OF THE AREA DURING THAT
PERIOD. THIS WOULD LIKELY BE BELOW ADVISORY CRITERIA...ALTHOUGH SOME
LOCATIONS COULD NEAR THE 3 INCH IN 12 HOUR MARK DURING THE DAY ON
FRIDAY...ESPECIALLY TOWARDS THE WISCONSIN BORDER.
ONCE THIS SYSTEM DEPARTS TO THE EAST ON SATURDAY NIGHT...HIGH
PRESSURE AND UPPER RIDGING WILL MOVE INTO THE AREA AND LEAD TO A
QUIET AND DRY END TO THE WEEKEND AND LIKELY INTO MONDAY. 850MB TEMPS
SHOULD BE WARMER THAN -10C AND THUS WOULDN/T EXPECT ANY CONCERN FOR
LIGHT LAKE EFFECT ON SUNDAY...ESPECIALLY SINCE WINDS WILL BE BACKING
TO THE SOUTH AND PULLING WARMER AIR OVER THE AREA FOR SUNDAY NIGHT.
ATTENTION THEN TURNS TO THE NEXT WAVE EXITING THE FOUR CORNERS
REGION ON SUNDAY NIGHT AND MOVING TOWARDS THE GREAT LAKES ON MONDAY
INTO TUESDAY. AS IS TRADITIONALLY THE CASE...THE GFS IS ON THE FAST
SIDE WITH THE SYSTEM AND HAVING IT ARRIVE ON MONDAY...WHILE THE
ECMWF IS MORE TOWARDS TUESDAY/WEDNESDAY. THERE ARE ALSO DIFFERENCES
IN THE EXACT TRACK...SO WILL JUST MENTION CHANCE/SLIGHT POPS AT
THIS POINT.
AS FOR TEMPERATURES...EXPECT TO SEE A GRADUAL WARMING TREND FOR THE
SECOND HALF OF THE WORK WEEK...WITH HIGHS THIS WEEKEND AND INTO THE
FIRST PART OF NEXT WEEK AT OR SLIGHTLY ABOVE NORMAL.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY)
ISSUED AT 430 PM EST TUE FEB 19 2013
CMX...EXPECT PREDOMINANT VLIFR CONDITIONS TODAY AS VERY STRONG NNW
WINDS COMBINE WITH LAKE ENHANCED SNOW TO PRODUCE NEAR BLIZZARD
CONDITIONS AT TIMES FOR MUCH OF TODAY. THE WINDS MAY DIMINISH ENOUGH
TOWARD THIS EVENING FOR SOME IMPROVEMENT WITH LIFR/IFR CONDITIONS
AND SHOULD IMPROVE TO MVFR ON WEDNESDAY AS DRIER AIR MOVES IN FM
NORTH OF THE LAKE.
IWD...SN/BLSN WILL ALSO KEEP MAINLY IFR/LIFR CONDITIONS AT IWD.
THERE SHOULD BE IMPROVEMENT TO MVFR BY WEDNESDAY MORNING AS THE
WINDS SLOWLY DIMINISH ONCE THE LO SHIFTS FARTHER TO THE E.
SAW...EXPECT PREDOMINANT IFR CONDITIONS THIS AFTERNOON IN SNOW AND
BLOWING SNOW WITH GUSTY NW WINDS. AS THE LOW PULLS OFF TO THE E
TONIGHT...AND WINDS DIE DOWN SOME EXPECT IMPROVEMENT TO MVFR THIS
EVENING WHICH WILL CONTINUE INTO WEDNESDAY.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 430 PM EST TUE FEB 19 2013
STRONG WRAPPED UP SFC LOW EAST OF LAKE SUPERIOR WILL HEAD TOWARD
WESTERN QUEBEC TONIGHT WHILE BEGINNING TO WEAKEN. VERY TIGHT
PRESSURE GRADIENT PRESENT THROUGH THIS EVENING COMBINED WITH COLD
AIR ADVECTION AND STRONG WINDS ALOFT WILL MAINTAIN STRONG GALES WITH
FREQUENT STORM FORCE GUSTS OVER THE EASTERN HALF OF LK SUPERIOR
THROUGH THIS EVENING. EXTENDED STORM WARNINGS FOR LSZ266 THROUGH
THIS EVENING. WINDS WILL BE SLOW TO DIMINISH WITH GALES PERSISTING
OVER CENTRAL AND ERN LK SUPERIOR THROUGH WED. HEAVY FREEZING SPRAY
WILL CONTINUE THROUGH THURSDAY MORNING. HIGH PRESSURE CROSSING ON
THURSDAY WILL ALLOW WINDS TO RELAX AND HEAVY FREEZING SPRAY TO
SUBSIDE. EXPECT EAST WINDS 20-30 KTS ON FRIDAY INTO FRIDAY NIGHT AS
LOW PRESSURE MOVES IN FROM THE CENTRAL PLAINS. WINDS FOR THE
UPCOMING WEEKEND NO MORE THAN 20 KTS AS WEAK PRESSURE GRADIENT
PREVAILS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER WEATHER ADVISORY UNTIL MIDNIGHT EST /11 PM CST/ TONIGHT
FOR MIZ002-004-009-013-084.
WINTER STORM WARNING UNTIL 5 PM EST WEDNESDAY FOR MIZ007-014-085.
BLIZZARD WARNING UNTIL 1 AM EST WEDNESDAY FOR MIZ001-003.
BLIZZARD WARNING UNTIL 5 PM EST WEDNESDAY FOR MIZ006.
WINTER STORM WARNING UNTIL MIDNIGHT EST TONIGHT FOR MIZ005.
LAKE SUPERIOR...
HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST /6 AM CST/ THURSDAY
FOR LSZ162-240>251-263-265-267.
GALE WARNING UNTIL 7 PM EST WEDNESDAY FOR LSZ245>251-265-267.
HEAVY FREEZING SPRAY WARNING UNTIL 1 PM EST THURSDAY FOR LSZ264-
266.
STORM WARNING UNTIL 11 PM EST THIS EVENING FOR LSZ266.
GALE WARNING UNTIL 1 PM EST WEDNESDAY FOR LSZ243-244-264.
GALE WARNING UNTIL 5 AM EST /4 AM CST/ WEDNESDAY FOR LSZ240>242-
263.
LAKE MICHIGAN...
GALE WARNING UNTIL 7 AM EST WEDNESDAY FOR LMZ248-250.
&&
$$
SHORT TERM...VOSS
LONG TERM...SRF
AVIATION...VOSS
MARINE...VOSS
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
1259 PM EST TUE FEB 19 2013
.AVIATION...
//DISCUSSION...
GUSTY WEST WINDS WILL CONTINUE THROUGH THE AFTERNOON AND EARLY
EVENING...WITH GUSTS UP TO 35 KNOTS. GUSTS WILL SUBSIDE OVERNIGHT AS
THE MIXED LAYER DECREASES...BUT SUSTAINED WINDS WILL STILL STAY UP
FROM THE WEST AT AT 14 TO 20 KNOTS...BEFORE TURNING NORTHWEST
TOWARDS SUNRISE. SNOW SHOWERS WILL ALSO CONTINUE TO STREAM OVER THE
AREA AS MOISTURE WRAPS INTO THE AREA ON THE BACKSIDE OF A LOW
PRESSURE SYSTEM THAT PUSHED ACROSS NORTHERN MICHIGAN EARLIER
TODAY...WITH SOME ENHANCEMENT FROM FLOW OVER LAKE MICHIGAN. MVFR
VISIBILITIES/CEILINGS WILL PREVAIL THROUGH THE AFTERNOON...WITH DIPS
INTO IFR LIKELY IN THE HEAVIER BURSTS OF SNOW. THESE CONDITIONS ARE
SIMILAR TO WHAT WE HAVE SEEN ACROSS THE AREA OVER THE PAST SEVERAL
HOURS...ALTHOUGH CEILINGS HAVE RISEN A LITTLE BIT AS MIXING
INCREASES. SHOWERS WILL DECREASE IN COVERAGE AND INTENSITY THIS
EVENING...AND BECOME MORE FOCUSED FROM PTK SOUTHWARD OVERNIGHT AS
FLOW OFF LAKE MICHIGAN TURNS MORE TO THE NORTHWEST.
FOR DTW...MVFR CEILINGS/VISIBILITIES WILL PREVAIL THROUGH THE
AFTERNOON...THOUGH BRIEF PERIODS OF VFR WILL BE POSSIBLE IN BETWEEN
SNOW SHOWERS. SNOW SHOWERS WILL CONTINUE OVERNIGHT...BUT WILL BECOME
LESS WIDESPREAD AS SNOW BECOMES MORE LAKE EFFECT DOMINATED AND FLOW
OFF LAKE MICHIGAN TURNS NORTHWEST.
//DTW THRESHOLD THREATS...
* HIGH CONFIDENCE IN CEILING BELOW 5000 FEET TODAY THROUGH TONIGHT.
* HIGH CONFIDENCE IN SNOW AS PRECIPITATION TYPE TODAY AND TONIGHT.
&&
.PREV DISCUSSION...ISSUED 1134 AM EST TUE FEB 19 2013
UPDATE...
WINDS HAVE BEEN FALLING A LITTLE SHY OF ADVISORY CRITERIA...ASIDE
FROM AN INITIAL BURST WITH 40 MPH GUSTS THAT ACCOMPANIED THE
PASSAGE OF THE COLD FRONT EARLY THIS MORNING. LOOKING AT FORECAST
SOUNDINGS FROM 12Z MODEL DATA...IT STILL APPEARS POSSIBLE FOR GUSTS
TO ATTAIN SPEEDS OF 40 TO 45 MPH AS THE MIXED LAYER DEEPENS THIS
AFTERNOON. WILL THEREFORE KEEP THE WIND ADVISORY INTACT...AT LEAST
INTO THE MID-AFTERNOON BEFORE REASSESSING.
SNOW HAS ALSO BEEN SPREADING INTO THE AREA ON THE BACKSIDE OF THE
SYSTEM...AS MOISTURE DEPTH DEEPENS ONCE AGAIN BEHIND THE MID-LEVEL
DRY SLOT AND AS PVA INCREASES AHEAD OF THE UPPER LOW. LAKE
ENHANCEMENT WILL ALSO CONTRIBUTE BUT STILL EXPECT HEAVIER SNOW TO
STAY TO OUR WEST. ACCUMULATIONS BETWEEN 0.5 AND 2 INCHES STILL
LOOK GOOD FOR THIS SIDE OF THE STATE. BIGGEST CONCERN WILL BE
REDUCED VISIBILITIES IN HEAVIER BURSTS OF SNOW.
PREV DISCUSSION...ISSUED 347 AM EST TUE FEB 19 2013
SHORT TERM... TODAY AND TONIGHT
MILD AND WET CONDITIONS THROUGHOUT SE MICHIGAN DURING THE EARLY
MORNING WILL BE KICKED OUT OF THE AREA BY A STRONG COLD FRONT
PASSING THROUGH AROUND SUNRISE. THE MAIN CONCERN WITH THIS FRONT
WILL BE PEAK WIND GUSTS REACHING 45 MPH ADVISORY CRITERIA IN THE
STRONG WESTERLY FLOW BEHIND IT, BUT THE COMBINATION OF FALLING
TEMPERATURES AND SNOW SHOWERS WILL ALSO ADD A LAYER OF HARSHNESS TO
CONDITIONS THROUGH THE DAY. EXPECT TEMPERATURES TO FALL TOWARD THE
MID AND UPPER 20S BY LATE MORNING, STRUGGLE TO REMAIN IN THE 20S
DURING THE AFTERNOON WITH SINGLE DIGIT WIND CHILL, AND THEN GIVE WAY
TO LOWS WELL DOWN INTO THE TEENS TONIGHT WITH WIND CHILL ABOUT 5
BELOW AFTER MIDNIGHT.
UPSTREAM OBSERVATIONS, ALONG WITH MODEL ISALLOBARIC FIELDS, INDICATE
THE STRONGEST WIND GUSTS OF 40 TO 50 KNOTS OVER CENTRAL INDIANA
OCCURRED WITHIN THE STEEPEST ISALLOBARIC GRADIENT ASSOCIATED WITH A
PEAK 3 HOUR PRESSURE RISE STARTING OFF CLOSE TO 10 MB. THIS PRESSURE
RISE CENTER IS SHOWN TO WEAKEN FROM NEARLY 10 MB TO 3-4 MB IN THE
NAM12 AND HIGH RES RAP MODELS AS THE FRONT MOVES THROUGH WESTERN
LOWER MICHIGAN AND THE REST OF INDIANA AND OHIO. THIS WEAKENING OF
THE ISALLOBARIC COMPONENT OF DYNAMIC FORCING WILL LIKELY RESULT IN A
SHORTER DURATION OF PEAK GUSTS AROUND 45 MPH IN OUR AREA ALONG AND
IMMEDIATELY POST FRONT. AFTER THAT, EXPECT A FEW HOURS OF WIND GUSTS
LESS THAN 40 MPH UNTIL COLD ADVECTION AND SYSTEM RELATIVE ISENTROPIC
DESCENT RAMPS UP LEADING TO STEEPENING LAPSE RATES IN A DEEPENING
BOUNDARY LAYER. DOWNWARD MOMENTUM TRANSPORT WILL THEN BE SUFFICIENT
FOR GUSTS TO REACH 45 MPH AGAIN BY LATE MORNING THROUGH THE
AFTERNOON. GUSTS WILL DIMINISH BY TONIGHT BUT WILL REMAIN IN THE 30
MPH RANGE AS THE BOUNDARY LAYER REMAINS WELL MIXED AFTER SUNSET.
AFTER THE DRY SLOT KEEPS SNOW AT BAY DURING THE MORNING, AN
EXPANSIVE AREA OF MID LEVEL MOISTURE WRAPPING AROUND THE WESTERN
FLANK OF THE LOW WILL DRIVE THE PATTERN OF SNOW DURING THE AFTERNOON
THROUGH TONIGHT. EARLY MORNING RADAR COMPOSITES SHOW THIS COMING
TOGETHER OVER THE UPPER MIDWEST AT PRESS TIME ADDING CONFIDENCE TO
THE EXPECTATION OF A HIGH POP/LOW ACCUMULATION SCENARIO. THIS
MOISTURE WILL SEED ENHANCEMENT FROM LAKE MICHIGAN AS INSTABILITY
INCREASES INTO THE 15-20C RANGE FOR LAKE TO 850 MB DELTA-T. THE MAIN
LIMITING FACTOR WILL BE THE STRONG WIND SPEED AND STEADY VEERING
TREND THAT WILL PREVENT ANY DOMINANT BAND FORMATION. PLAN TO FAVOR
THE TRI CITIES AND THUMB WITH CATEGORICAL POPS DURING THE AFTERNOON
AND LIKELY INTO THE THE EVENING WITH 1 TO 2 INCHES OF ACCUMULATION
BEFORE THE WIND SHIFT TOWARD THE NORTHWEST FAVORS AREAS SOUTH OF
INTERSTATE 69 TOWARD SUNRISE WEDNESDAY.
LONG TERM...
ALTHOUGH THE 500 MB LOW/MID LEVEL COLD POOL WILL BE MOVING INTO NEW
ENGLAND ON WEDNESDAY...A SHALLOW (SFC-925 MB) BACK DOOR COLD FRONT
WILL ATTEMPT TO MAKE INROADS INTO SOUTHERN LOWER MICHIGAN.
925 MB TEMPS OF -16 TO -17 C FORECASTED TO WORK THROUGH THE THUMB
REGION...WITH LOW LEVEL FLOW JUST SLIGHTLY WEST OF DUE NORTH.
SO...REASONABLE EXPECTATION SOME LAKE EFFECT SNOW SHOWER ACTIVITY
WILL BRUSH THE SHORELINE...BUT SHALLOW NATURE OF THE ACTIVITY
(MODERATING 850 MB TEMPS) SHOULD PREVENT ACTIVITY FROM GETTING OUT
OF HAND. 1042 MB HIGH OVER ONTARIO WILL NOSE INTO SOUTHEAST MICHIGAN
ON THURSDAY...AS AMPLIFIED UPPER LEVEL RIDGE MOVES OVER THE WESTERN
GREAT LAKES. POTENT UPPER WAVE JUST OFF THE PACIFIC NORTHWEST COAST
EARLY THIS MORNING STILL PROGGED TO ROTATE THROUGH THE FOUR CORNERS
REGION LATE WEDNESDAY...BUT TRACKING JUST A TOUCH FARTHER
EAST...OVER/NEAR SIOUX FALLS SOUTH DAKOTA THURSDAY NIGHT (PER 00Z
GFS/EURO). DRAMATIC WEST-EAST SHEARING OF THE UPPER LEVEL
CIRCULATION WILL OCCUR...BUT STILL A PERIOD OF LARGE SCALE ASCENT/PV
ADVECTION FRIDAY MORNING TO OCCUR OVER SOUTHEAST MICHIGAN. THE BULK
OF THE LIFT WILL BE USED UP JUST TO SATURATE THE LOW LEVELS...AS THE
PREVIOUSLY MENTIONED HIGH OVER ONTARIO LEADS TO EASTERLY DRY LOW
LEVEL FLOW PERSISTING INTO FRIDAY. 00Z GFS NOT EVEN GIVING US A
TENTH OF AN INCH OF QPF...AS DEEPER MOISTURE SEEN IN THE 850-700
MB/PW FIELDS SKIRTS JUST TO THE SOUTHEAST OF THE CWA. STILL...DECENT
SHOT OF MOISTURE ADVECTION...AND PREFERENCE IS WITH THE STRONGER
CANADIAN/EURO WHICH MAINTAINS THE 500 MB LOW OVER MINNESOTA INTO THE
FIRST HALF OF THE WEEKEND. QPF FROM THOSE MODELS SUPPORTS A SOLID 1
TO TWO INCHES OF SNOW ON FRIDAY...WITH RELATIVELY LOW SNOW TO LIQUID
RATIOS...AS ZERO OR SLIGHTLY BETTER 850 MB TEMPS SEEN REACHING THE
OHIO BORDER.
THE MODEST MID LEVEL COLD POOL OVER MINNESOTA WILL BREAK OFF TO THE
EAST FOR THE WEEKEND...KEEPING TEMPERATURES IN CHECK...AS 850 MB
TEMPS LOOK TO BE HOVERING AROUND -10 C...AND WITH LIMITED
SUNSHINE...MAXES EXPECTED TO REMAIN GENERALLY BELOW 40 DEGREES.
ALTHOUGH...WE WILL HAVE THE DRY SLOT WORKING THROUGH SATURDAY
MORNING...WHICH COULD BE THE DAY WE SNEAK UP TO 40 DEGREES.
MARINE...
DEEP LOW PRESSURE MOVING THROUGH THE STRAITS WILL PULL A STRONG COLD
FRONT THROUGH LAKE HURON AND LOWER MICHIGAN EARLY IN THE MORNING.
WESTERLY GALES WILL DEVELOP AFTER THE FRONTAL PASSAGE AND THEN
PERSIST TONIGHT THROUGH WEDNESDAY WHILE VEERING TO NORTHWEST OVER
THE OPEN WATERS OF LAKE HURON. POLAR AIR SURGING BACK INTO THE
REGION WILL CHANGE RAIN BACK TO SNOW AND ALSO LEAD TO A SUBSTANTIAL
FREEZING SPRAY HAZARD OVER THE OPEN WATERS TONIGHT THROUGH
WEDNESDAY. THE STRONG WINDS AND RESULTING LARGE WAVES WILL COMBINE
WITH NEAR IDEAL WATER TEMPERATURE FOR WIDESPREAD FREEZING SPRAY TO
BECOME HEAVY. MARINE CONDITIONS WILL THEN IMPROVE CONSIDERABLY BY
THURSDAY AS HIGH PRESSURE SETTLES OVER THE REGION.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...WIND ADVISORY...MIZ047-MIZ048-MIZ049-MIZ053-MIZ054-MIZ055-MIZ060-
MIZ061-MIZ062-MIZ063-MIZ068-MIZ069-MIZ070-MIZ075-MIZ076-MIZ082-
MIZ083...UNTIL 7 PM TUESDAY.
LAKE HURON...
GALE WARNING...LHZ361-LHZ362-LHZ363...UNTIL 7 PM WEDNESDAY.
HEAVY FREEZING SPRAY WARNING...LHZ361-LHZ362-LHZ363-LHZ462-LHZ463-
LHZ464...FROM 7 PM TUESDAY TO 7 PM WEDNESDAY.
GALE WARNING...LHZ421-LHZ422-LHZ441-LHZ442-LHZ443-LHZ462-LHZ463-
LHZ464...UNTIL MIDNIGHT WEDNESDAY.
LAKE ST CLAIR...
GALE WARNING...UNTIL MIDNIGHT WEDNESDAY.
MI WATERS OF LAKE ERIE...
GALE WARNING...UNTIL MIDNIGHT WEDNESDAY.
&&
$$
AVIATION.....HLO
UPDATE.......HLO
SHORT TERM...BT
LONG TERM....SF
MARINE.......BT
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
1134 AM EST TUE FEB 19 2013
.UPDATE...
WINDS HAVE BEEN FALLING A LITTLE SHY OF ADVISORY CRITERIA...ASIDE
FROM AN INITIAL BURST WITH 40 MPH GUSTS THAT ACCOMPANIED THE
PASSAGE OF THE COLD FRONT EARLY THIS MORNING. LOOKING AT FORECAST
SOUNDINGS FROM 12Z MODEL DATA...IT STILL APPEARS POSSIBLE FOR GUSTS
TO ATTAIN SPEEDS OF 40 TO 45 MPH AS THE MIXED LAYER DEEPENS THIS
AFTERNOON. WILL THEREFORE KEEP THE WIND ADVISORY INTACT...AT LEAST
INTO THE MID-AFTERNOON BEFORE REASSESSING.
SNOW HAS ALSO BEEN SPREADING INTO THE AREA ON THE BACKSIDE OF THE
SYSTEM...AS MOISTURE DEPTH DEEPENS ONCE AGAIN BEHIND THE MID-LEVEL
DRY SLOT AND AS PVA INCREASES AHEAD OF THE UPPER LOW. LAKE
ENHANCEMENT WILL ALSO CONTRIBUTE BUT STILL EXPECT HEAVIER SNOW TO
STAY TO OUR WEST. ACCUMULATIONS BETWEEN 0.5 AND 2 INCHES STILL
LOOK GOOD FOR THIS SIDE OF THE STATE. BIGGEST CONCERN WILL BE
REDUCED VISIBILITIES IN HEAVIER BURSTS OF SNOW.
&&
.AVIATION...ISSUED 733 AM EST TUE FEB 19 2013
//DISCUSSION...
STRONG SOUTHWEST WIND AND FALLING TEMPERATURE WILL BE THE MAIN
AVIATION CONCERN DURING THE MORNING AS MID LEVEL DRY AIR INITIALLY
KEEPS SNOW SHOWERS AT A MINIMUM. CEILING WILL REMAIN NO BETTER
THAN MVFR, HOWEVER, AND THEN SNOW WILL INCREASE IN COVERAGE AND
INTENSITY DURING THE LATE MORNING AND THROUGH THE AFTERNOON, ALL
WHILE WESTERLY WIND GUSTS INCREASE TO ABOUT 35 KNOTS. IFR
VISIBILITY RESTRICTION IN SNOW AND BLOWING SNOW IS LIKELY AT FNT
AND MBS INTO THE EARLY EVENING BEFORE BOTH THE SNOW AND THE WIND
GUSTS DIMINISH THROUGH TONIGHT. MVFR CEILING AND SOME FLURRIES OFF
THE SOUTH END OF LAKE MICHIGAN WILL BE POSSIBLE IN THE DTW AREA
TOWARD SUNRISE WEDNESDAY.
FOR DTW... A POCKET OF SNOW IN THE CHICAGO AREA AT PRESS TIME WILL
MOVE THROUGH SOUTHERN MICHIGAN DURING THE MORNING AND INTO THE DTW
AREA BY NOON WHILE WESTERLY WIND GUSTS CONTINUE IN THE 30 TO 35 KNOT
RANGE. EXPECT ACCUMULATION TO BE LESS THAN AN INCH DURING THE
AFTERNOON WITH THIS ACTIVITY AS TEMPERATURES FALL IN THE MID AND
UPPER 20S.
//DTW THRESHOLD THREATS...
* HIGH CONFIDENCE IN CEILING BELOW 5000 FEET TODAY THROUGH TONIGHT.
* HIGH CONFIDENCE IN SNOW AS PRECIPITATION TYPE TODAY AND TONIGHT.
&&
.PREV DISCUSSION...ISSUED 347 AM EST TUE FEB 19 2013
SHORT TERM... TODAY AND TONIGHT
MILD AND WET CONDITIONS THROUGHOUT SE MICHIGAN DURING THE EARLY
MORNING WILL BE KICKED OUT OF THE AREA BY A STRONG COLD FRONT
PASSING THROUGH AROUND SUNRISE. THE MAIN CONCERN WITH THIS FRONT
WILL BE PEAK WIND GUSTS REACHING 45 MPH ADVISORY CRITERIA IN THE
STRONG WESTERLY FLOW BEHIND IT, BUT THE COMBINATION OF FALLING
TEMPERATURES AND SNOW SHOWERS WILL ALSO ADD A LAYER OF HARSHNESS TO
CONDITIONS THROUGH THE DAY. EXPECT TEMPERATURES TO FALL TOWARD THE
MID AND UPPER 20S BY LATE MORNING, STRUGGLE TO REMAIN IN THE 20S
DURING THE AFTERNOON WITH SINGLE DIGIT WIND CHILL, AND THEN GIVE WAY
TO LOWS WELL DOWN INTO THE TEENS TONIGHT WITH WIND CHILL ABOUT 5
BELOW AFTER MIDNIGHT.
UPSTREAM OBSERVATIONS, ALONG WITH MODEL ISALLOBARIC FIELDS, INDICATE
THE STRONGEST WIND GUSTS OF 40 TO 50 KNOTS OVER CENTRAL INDIANA
OCCURRED WITHIN THE STEEPEST ISALLOBARIC GRADIENT ASSOCIATED WITH A
PEAK 3 HOUR PRESSURE RISE STARTING OFF CLOSE TO 10 MB. THIS PRESSURE
RISE CENTER IS SHOWN TO WEAKEN FROM NEARLY 10 MB TO 3-4 MB IN THE
NAM12 AND HIGH RES RAP MODELS AS THE FRONT MOVES THROUGH WESTERN
LOWER MICHIGAN AND THE REST OF INDIANA AND OHIO. THIS WEAKENING OF
THE ISALLOBARIC COMPONENT OF DYNAMIC FORCING WILL LIKELY RESULT IN A
SHORTER DURATION OF PEAK GUSTS AROUND 45 MPH IN OUR AREA ALONG AND
IMMEDIATELY POST FRONT. AFTER THAT, EXPECT A FEW HOURS OF WIND GUSTS
LESS THAN 40 MPH UNTIL COLD ADVECTION AND SYSTEM RELATIVE ISENTROPIC
DESCENT RAMPS UP LEADING TO STEEPENING LAPSE RATES IN A DEEPENING
BOUNDARY LAYER. DOWNWARD MOMENTUM TRANSPORT WILL THEN BE SUFFICIENT
FOR GUSTS TO REACH 45 MPH AGAIN BY LATE MORNING THROUGH THE
AFTERNOON. GUSTS WILL DIMINISH BY TONIGHT BUT WILL REMAIN IN THE 30
MPH RANGE AS THE BOUNDARY LAYER REMAINS WELL MIXED AFTER SUNSET.
AFTER THE DRY SLOT KEEPS SNOW AT BAY DURING THE MORNING, AN
EXPANSIVE AREA OF MID LEVEL MOISTURE WRAPPING AROUND THE WESTERN
FLANK OF THE LOW WILL DRIVE THE PATTERN OF SNOW DURING THE AFTERNOON
THROUGH TONIGHT. EARLY MORNING RADAR COMPOSITES SHOW THIS COMING
TOGETHER OVER THE UPPER MIDWEST AT PRESS TIME ADDING CONFIDENCE TO
THE EXPECTATION OF A HIGH POP/LOW ACCUMULATION SCENARIO. THIS
MOISTURE WILL SEED ENHANCEMENT FROM LAKE MICHIGAN AS INSTABILITY
INCREASES INTO THE 15-20C RANGE FOR LAKE TO 850 MB DELTA-T. THE MAIN
LIMITING FACTOR WILL BE THE STRONG WIND SPEED AND STEADY VEERING
TREND THAT WILL PREVENT ANY DOMINANT BAND FORMATION. PLAN TO FAVOR
THE TRI CITIES AND THUMB WITH CATEGORICAL POPS DURING THE AFTERNOON
AND LIKELY INTO THE THE EVENING WITH 1 TO 2 INCHES OF ACCUMULATION
BEFORE THE WIND SHIFT TOWARD THE NORTHWEST FAVORS AREAS SOUTH OF
INTERSTATE 69 TOWARD SUNRISE WEDNESDAY.
LONG TERM...
ALTHOUGH THE 500 MB LOW/MID LEVEL COLD POOL WILL BE MOVING INTO NEW
ENGLAND ON WEDNESDAY...A SHALLOW (SFC-925 MB) BACK DOOR COLD FRONT
WILL ATTEMPT TO MAKE INROADS INTO SOUTHERN LOWER MICHIGAN.
925 MB TEMPS OF -16 TO -17 C FORECASTED TO WORK THROUGH THE THUMB
REGION...WITH LOW LEVEL FLOW JUST SLIGHTLY WEST OF DUE NORTH.
SO...REASONABLE EXPECTATION SOME LAKE EFFECT SNOW SHOWER ACTIVITY
WILL BRUSH THE SHORELINE...BUT SHALLOW NATURE OF THE ACTIVITY
(MODERATING 850 MB TEMPS) SHOULD PREVENT ACTIVITY FROM GETTING OUT
OF HAND. 1042 MB HIGH OVER ONTARIO WILL NOSE INTO SOUTHEAST MICHIGAN
ON THURSDAY...AS AMPLIFIED UPPER LEVEL RIDGE MOVES OVER THE WESTERN
GREAT LAKES. POTENT UPPER WAVE JUST OFF THE PACIFIC NORTHWEST COAST
EARLY THIS MORNING STILL PROGGED TO ROTATE THROUGH THE FOUR CORNERS
REGION LATE WEDNESDAY...BUT TRACKING JUST A TOUCH FARTHER
EAST...OVER/NEAR SIOUX FALLS SOUTH DAKOTA THURSDAY NIGHT (PER 00Z
GFS/EURO). DRAMATIC WEST-EAST SHEARING OF THE UPPER LEVEL
CIRCULATION WILL OCCUR...BUT STILL A PERIOD OF LARGE SCALE ASCENT/PV
ADVECTION FRIDAY MORNING TO OCCUR OVER SOUTHEAST MICHIGAN. THE BULK
OF THE LIFT WILL BE USED UP JUST TO SATURATE THE LOW LEVELS...AS THE
PREVIOUSLY MENTIONED HIGH OVER ONTARIO LEADS TO EASTERLY DRY LOW
LEVEL FLOW PERSISTING INTO FRIDAY. 00Z GFS NOT EVEN GIVING US A
TENTH OF AN INCH OF QPF...AS DEEPER MOISTURE SEEN IN THE 850-700
MB/PW FIELDS SKIRTS JUST TO THE SOUTHEAST OF THE CWA. STILL...DECENT
SHOT OF MOISTURE ADVECTION...AND PREFERENCE IS WITH THE STRONGER
CANADIAN/EURO WHICH MAINTAINS THE 500 MB LOW OVER MINNESOTA INTO THE
FIRST HALF OF THE WEEKEND. QPF FROM THOSE MODELS SUPPORTS A SOLID 1
TO TWO INCHES OF SNOW ON FRIDAY...WITH RELATIVELY LOW SNOW TO LIQUID
RATIOS...AS ZERO OR SLIGHTLY BETTER 850 MB TEMPS SEEN REACHING THE
OHIO BORDER.
THE MODEST MID LEVEL COLD POOL OVER MINNESOTA WILL BREAK OFF TO THE
EAST FOR THE WEEKEND...KEEPING TEMPERATURES IN CHECK...AS 850 MB
TEMPS LOOK TO BE HOVERING AROUND -10 C...AND WITH LIMITED
SUNSHINE...MAXES EXPECTED TO REMAIN GENERALLY BELOW 40 DEGREES.
ALTHOUGH...WE WILL HAVE THE DRY SLOT WORKING THROUGH SATURDAY
MORNING...WHICH COULD BE THE DAY WE SNEAK UP TO 40 DEGREES.
MARINE...
DEEP LOW PRESSURE MOVING THROUGH THE STRAITS WILL PULL A STRONG COLD
FRONT THROUGH LAKE HURON AND LOWER MICHIGAN EARLY IN THE MORNING.
WESTERLY GALES WILL DEVELOP AFTER THE FRONTAL PASSAGE AND THEN
PERSIST TONIGHT THROUGH WEDNESDAY WHILE VEERING TO NORTHWEST OVER
THE OPEN WATERS OF LAKE HURON. POLAR AIR SURGING BACK INTO THE
REGION WILL CHANGE RAIN BACK TO SNOW AND ALSO LEAD TO A SUBSTANTIAL
FREEZING SPRAY HAZARD OVER THE OPEN WATERS TONIGHT THROUGH
WEDNESDAY. THE STRONG WINDS AND RESULTING LARGE WAVES WILL COMBINE
WITH NEAR IDEAL WATER TEMPERATURE FOR WIDESPREAD FREEZING SPRAY TO
BECOME HEAVY. MARINE CONDITIONS WILL THEN IMPROVE CONSIDERABLY BY
THURSDAY AS HIGH PRESSURE SETTLES OVER THE REGION.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...WIND ADVISORY...MIZ047-MIZ048-MIZ049-MIZ053-MIZ054-MIZ055-MIZ060-
MIZ061-MIZ062-MIZ063-MIZ068-MIZ069-MIZ070-MIZ075-MIZ076-MIZ082-
MIZ083...UNTIL 7 PM TUESDAY.
LAKE HURON...
GALE WARNING...LHZ361...UNTIL 7 PM WEDNESDAY.
HEAVY FREEZING SPRAY WARNING...LHZ361-LHZ362-LHZ363-LHZ462-LHZ463-
LHZ464...FROM 7 PM TUESDAY TO 7 PM WEDNESDAY.
GALE WARNING...LHZ362-LHZ363...UNTIL 7 PM WEDNESDAY.
GALE WARNING...LHZ421-LHZ422-LHZ441-LHZ442-LHZ443-LHZ462-LHZ463-
LHZ464...UNTIL MIDNIGHT WEDNESDAY.
LAKE ST CLAIR...
GALE WARNING...UNTIL MIDNIGHT WEDNESDAY.
MI WATERS OF LAKE ERIE...
GALE WARNING...UNTIL MIDNIGHT WEDNESDAY.
&&
$$
UPDATE.......HLO
AVIATION.....BT
SHORT TERM...BT
LONG TERM....SF
MARINE.......BT
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
733 AM EST TUE FEB 19 2013
.AVIATION...
//DISCUSSION...
STRONG SOUTHWEST WIND AND FALLING TEMPERATURE WILL BE THE MAIN
AVIATION CONCERN DURING THE MORNING AS MID LEVEL DRY AIR INITIALLY
KEEPS SNOW SHOWERS AT A MINIMUM. CEILING WILL REMAIN NO BETTER
THAN MVFR, HOWEVER, AND THEN SNOW WILL INCREASE IN COVERAGE AND
INTENSITY DURING THE LATE MORNING AND THROUGH THE AFTERNOON, ALL
WHILE WESTERLY WIND GUSTS INCREASE TO ABOUT 35 KNOTS. IFR
VISIBILITY RESTRICTION IN SNOW AND BLOWING SNOW IS LIKELY AT FNT
AND MBS INTO THE EARLY EVENING BEFORE BOTH THE SNOW AND THE WIND
GUSTS DIMINISH THROUGH TONIGHT. MVFR CEILING AND SOME FLURRIES OFF
THE SOUTH END OF LAKE MICHIGAN WILL BE POSSIBLE IN THE DTW AREA
TOWARD SUNRISE WEDNESDAY.
FOR DTW... A POCKET OF SNOW IN THE CHICAGO AREA AT PRESS TIME WILL
MOVE THROUGH SOUTHERN MICHIGAN DURING THE MORNING AND INTO THE DTW
AREA BY NOON WHILE WESTERLY WIND GUSTS CONTINUE IN THE 30 TO 35 KNOT
RANGE. EXPECT ACCUMULATION TO BE LESS THAN AN INCH DURING THE
AFTERNOON WITH THIS ACTIVITY AS TEMPERATURES FALL IN THE MID AND
UPPER 20S.
//DTW THRESHOLD THREATS...
* HIGH CONFIDENCE IN CEILING BELOW 5000 FEET TODAY THROUGH TONIGHT.
* HIGH CONFIDENCE IN SNOW AS PRECIPITATION TYPE TODAY AND TONIGHT.
&&
.PREV DISCUSSION...ISSUED 347 AM EST TUE FEB 19 2013
SHORT TERM... TODAY AND TONIGHT
MILD AND WET CONDITIONS THROUGHOUT SE MICHIGAN DURING THE EARLY
MORNING WILL BE KICKED OUT OF THE AREA BY A STRONG COLD FRONT
PASSING THROUGH AROUND SUNRISE. THE MAIN CONCERN WITH THIS FRONT
WILL BE PEAK WIND GUSTS REACHING 45 MPH ADVISORY CRITERIA IN THE
STRONG WESTERLY FLOW BEHIND IT, BUT THE COMBINATION OF FALLING
TEMPERATURES AND SNOW SHOWERS WILL ALSO ADD A LAYER OF HARSHNESS TO
CONDITIONS THROUGH THE DAY. EXPECT TEMPERATURES TO FALL TOWARD THE
MID AND UPPER 20S BY LATE MORNING, STRUGGLE TO REMAIN IN THE 20S
DURING THE AFTERNOON WITH SINGLE DIGIT WIND CHILL, AND THEN GIVE WAY
TO LOWS WELL DOWN INTO THE TEENS TONIGHT WITH WIND CHILL ABOUT 5
BELOW AFTER MIDNIGHT.
UPSTREAM OBSERVATIONS, ALONG WITH MODEL ISALLOBARIC FIELDS, INDICATE
THE STRONGEST WIND GUSTS OF 40 TO 50 KNOTS OVER CENTRAL INDIANA
OCCURRED WITHIN THE STEEPEST ISALLOBARIC GRADIENT ASSOCIATED WITH A
PEAK 3 HOUR PRESSURE RISE STARTING OFF CLOSE TO 10 MB. THIS PRESSURE
RISE CENTER IS SHOWN TO WEAKEN FROM NEARLY 10 MB TO 3-4 MB IN THE
NAM12 AND HIGH RES RAP MODELS AS THE FRONT MOVES THROUGH WESTERN
LOWER MICHIGAN AND THE REST OF INDIANA AND OHIO. THIS WEAKENING OF
THE ISALLOBARIC COMPONENT OF DYNAMIC FORCING WILL LIKELY RESULT IN A
SHORTER DURATION OF PEAK GUSTS AROUND 45 MPH IN OUR AREA ALONG AND
IMMEDIATELY POST FRONT. AFTER THAT, EXPECT A FEW HOURS OF WIND GUSTS
LESS THAN 40 MPH UNTIL COLD ADVECTION AND SYSTEM RELATIVE ISENTROPIC
DESCENT RAMPS UP LEADING TO STEEPENING LAPSE RATES IN A DEEPENING
BOUNDARY LAYER. DOWNWARD MOMENTUM TRANSPORT WILL THEN BE SUFFICIENT
FOR GUSTS TO REACH 45 MPH AGAIN BY LATE MORNING THROUGH THE
AFTERNOON. GUSTS WILL DIMINISH BY TONIGHT BUT WILL REMAIN IN THE 30
MPH RANGE AS THE BOUNDARY LAYER REMAINS WELL MIXED AFTER SUNSET.
AFTER THE DRY SLOT KEEPS SNOW AT BAY DURING THE MORNING, AN
EXPANSIVE AREA OF MID LEVEL MOISTURE WRAPPING AROUND THE WESTERN
FLANK OF THE LOW WILL DRIVE THE PATTERN OF SNOW DURING THE AFTERNOON
THROUGH TONIGHT. EARLY MORNING RADAR COMPOSITES SHOW THIS COMING
TOGETHER OVER THE UPPER MIDWEST AT PRESS TIME ADDING CONFIDENCE TO
THE EXPECTATION OF A HIGH POP/LOW ACCUMULATION SCENARIO. THIS
MOISTURE WILL SEED ENHANCEMENT FROM LAKE MICHIGAN AS INSTABILITY
INCREASES INTO THE 15-20C RANGE FOR LAKE TO 850 MB DELTA-T. THE MAIN
LIMITING FACTOR WILL BE THE STRONG WIND SPEED AND STEADY VEERING
TREND THAT WILL PREVENT ANY DOMINANT BAND FORMATION. PLAN TO FAVOR
THE TRI CITIES AND THUMB WITH CATEGORICAL POPS DURING THE AFTERNOON
AND LIKELY INTO THE THE EVENING WITH 1 TO 2 INCHES OF ACCUMULATION
BEFORE THE WIND SHIFT TOWARD THE NORTHWEST FAVORS AREAS SOUTH OF
INTERSTATE 69 TOWARD SUNRISE WEDNESDAY.
LONG TERM...
ALTHOUGH THE 500 MB LOW/MID LEVEL COLD POOL WILL BE MOVING INTO NEW
ENGLAND ON WEDNESDAY...A SHALLOW (SFC-925 MB) BACK DOOR COLD FRONT
WILL ATTEMPT TO MAKE INROADS INTO SOUTHERN LOWER MICHIGAN.
925 MB TEMPS OF -16 TO -17 C FORECASTED TO WORK THROUGH THE THUMB
REGION...WITH LOW LEVEL FLOW JUST SLIGHTLY WEST OF DUE NORTH.
SO...REASONABLE EXPECTATION SOME LAKE EFFECT SNOW SHOWER ACTIVITY
WILL BRUSH THE SHORELINE...BUT SHALLOW NATURE OF THE ACTIVITY
(MODERATING 850 MB TEMPS) SHOULD PREVENT ACTIVITY FROM GETTING OUT
OF HAND. 1042 MB HIGH OVER ONTARIO WILL NOSE INTO SOUTHEAST MICHIGAN
ON THURSDAY...AS AMPLIFIED UPPER LEVEL RIDGE MOVES OVER THE WESTERN
GREAT LAKES. POTENT UPPER WAVE JUST OFF THE PACIFIC NORTHWEST COAST
EARLY THIS MORNING STILL PROGGED TO ROTATE THROUGH THE FOUR CORNERS
REGION LATE WEDNESDAY...BUT TRACKING JUST A TOUCH FARTHER
EAST...OVER/NEAR SIOUX FALLS SOUTH DAKOTA THURSDAY NIGHT (PER 00Z
GFS/EURO). DRAMATIC WEST-EAST SHEARING OF THE UPPER LEVEL
CIRCULATION WILL OCCUR...BUT STILL A PERIOD OF LARGE SCALE ASCENT/PV
ADVECTION FRIDAY MORNING TO OCCUR OVER SOUTHEAST MICHIGAN. THE BULK
OF THE LIFT WILL BE USED UP JUST TO SATURATE THE LOW LEVELS...AS THE
PREVIOUSLY MENTIONED HIGH OVER ONTARIO LEADS TO EASTERLY DRY LOW
LEVEL FLOW PERSISTING INTO FRIDAY. 00Z GFS NOT EVEN GIVING US A
TENTH OF AN INCH OF QPF...AS DEEPER MOISTURE SEEN IN THE 850-700
MB/PW FIELDS SKIRTS JUST TO THE SOUTHEAST OF THE CWA. STILL...DECENT
SHOT OF MOISTURE ADVECTION...AND PREFERENCE IS WITH THE STRONGER
CANADIAN/EURO WHICH MAINTAINS THE 500 MB LOW OVER MINNESOTA INTO THE
FIRST HALF OF THE WEEKEND. QPF FROM THOSE MODELS SUPPORTS A SOLID 1
TO TWO INCHES OF SNOW ON FRIDAY...WITH RELATIVELY LOW SNOW TO LIQUID
RATIOS...AS ZERO OR SLIGHTLY BETTER 850 MB TEMPS SEEN REACHING THE
OHIO BORDER.
THE MODEST MID LEVEL COLD POOL OVER MINNESOTA WILL BREAK OFF TO THE
EAST FOR THE WEEKEND...KEEPING TEMPERATURES IN CHECK...AS 850 MB
TEMPS LOOK TO BE HOVERING AROUND -10 C...AND WITH LIMITED
SUNSHINE...MAXES EXPECTED TO REMAIN GENERALLY BELOW 40 DEGREES.
ALTHOUGH...WE WILL HAVE THE DRY SLOT WORKING THROUGH SATURDAY
MORNING...WHICH COULD BE THE DAY WE SNEAK UP TO 40 DEGREES.
MARINE...
DEEP LOW PRESSURE MOVING THROUGH THE STRAITS WILL PULL A STRONG COLD
FRONT THROUGH LAKE HURON AND LOWER MICHIGAN EARLY IN THE MORNING.
WESTERLY GALES WILL DEVELOP AFTER THE FRONTAL PASSAGE AND THEN
PERSIST TONIGHT THROUGH WEDNESDAY WHILE VEERING TO NORTHWEST OVER
THE OPEN WATERS OF LAKE HURON. POLAR AIR SURGING BACK INTO THE
REGION WILL CHANGE RAIN BACK TO SNOW AND ALSO LEAD TO A SUBSTANTIAL
FREEZING SPRAY HAZARD OVER THE OPEN WATERS TONIGHT THROUGH
WEDNESDAY. THE STRONG WINDS AND RESULTING LARGE WAVES WILL COMBINE
WITH NEAR IDEAL WATER TEMPERATURE FOR WIDESPREAD FREEZING SPRAY TO
BECOME HEAVY. MARINE CONDITIONS WILL THEN IMPROVE CONSIDERABLY BY
THURSDAY AS HIGH PRESSURE SETTLES OVER THE REGION.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...WIND ADVISORY...MIZ047-MIZ048-MIZ049-MIZ053-MIZ054-MIZ055-MIZ060-
MIZ061-MIZ062-MIZ063-MIZ068-MIZ069-MIZ070-MIZ075-MIZ076-MIZ082-
MIZ083...UNTIL 7 PM TUESDAY.
LAKE HURON...
GALE WARNING...LHZ361...FROM NOON TUESDAY TO 7 PM WEDNESDAY.
HEAVY FREEZING SPRAY WARNING...LHZ361-LHZ362-LHZ363-LHZ462-LHZ463-
LHZ464...FROM 7 PM TUESDAY TO 7 PM WEDNESDAY.
GALE WARNING...LHZ362-LHZ363...UNTIL 7 PM WEDNESDAY.
GALE WARNING...LHZ421-LHZ422-LHZ441-LHZ442-LHZ443-LHZ462-LHZ463-
LHZ464...UNTIL MIDNIGHT WEDNESDAY.
LAKE ST CLAIR...
GALE WARNING...UNTIL MIDNIGHT WEDNESDAY.
MI WATERS OF LAKE ERIE...
GALE WARNING...UNTIL MIDNIGHT WEDNESDAY.
&&
$$
AVIATION.....BT
SHORT TERM...BT
LONG TERM....SF
MARINE.......BT
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
722 AM EST TUE FEB 19 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 539 AM EST TUE FEB 19 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL TROUGH FROM
HUDSON BAY THROUGH NW ONTARIO INTO WI/IL WAS BECOMING MORE
NEGATIVELY TILTED AS A 120 KT 300-250 JET MOVES FROM THE OHIO VALLEY
TOWARD THE EASTERN LAKES. THE BACK EDGE OF A WELL-DEFINED WARM
CONVEYOR SHIELD EXTENDED FROM NEAR CMX-DTW. UPPER LEVEL DIV WITH A
COUPLED JET STRUCTURE AND STRONG DEEP LAYER QVECTOR CONV SUPPORTED A
LARGE AREA OF MODERATE SNOW ACROSS LAKE SUPERIOR AND UPPER MI INTO
NRN WI. AT THE SFC...LOW PRES WAS DEEPENING AS IT MOVED THROUGH NRN
LAKE SUPERIOR AND AT 10Z WAS AROUND 987 MB NEAR BEAVER ISLAND. THE
TIGHTENING GRADIENT BETWEEN THE LOW AND A 1040 MB RIDGE OVER
MANITOBA INTO THE NRN PLAINS HAS RESULTED IN VERY GUSTY WINDS WITH
P59 ALREADY RECORDING GUSTS TO 49 MPH. RELATIVELY LOW SLR VALUES
NEAR 10/1 AND THE STRONG WINDS FRACTURING SNOW FLAKES HAVE KEPT SNOW
AMOUNTS GENERALLY IN THE 2 TO 3 INCH RANGE.
THE MODERATE TO STRONG 700-300 QVECTOR CONV AND FAVORABLE 280K-290K
ISENTROPIC LIFT INTO CNTRL AND EAST UPPER MICHIGAN WILL CONTINUE
WITH WIDESPEAD SYNOPTIC SNOW CONTINUING. ADDITIONAL SYNOPTIC QPF
VALUES OF AROUND 0.10 TO 0.20 INTO THE NRN CWA SHOULD PROVIDE
POTENTIAL FOR AN ADDITIONAL 1 TO 3 INCHES. LOW LEVEL CAA WITH 850 MB
TEMPS DROPPING INTO THE -15C TO -17C RANGE WILL BRING ADDITIONAL
LAKE ENHANCED SNOW FOR LOCATIONS FAVORED BY CYCLONIC 340-330 FLOW.
THIS WOULD AFFECT MOST OF NORTHERN UPPER MICHIGAN WITH LOW LEVEL
CONV FOCUSED NEAR THE MARQUETTE COUNTY SHORLINE AND INTO WRN ALGER
COUNTY. ADDITIONAL AMOUNTS FROM LAKE ENHANCED SNOW OF 1 TO 3 INCHES
ARE ALSO EXPECTED.
THE MAIN HAZARD HOWEVER...WILL BE THE VERY STRONG WINDS AS MODEL
MOMENTUMM TRANSFER PROFILES SUGGEST THAT WINDS WILL GUST IN THE
30-40 MPH RANGE...ESPECIALLY THIS MORNING. ALONG THE LAKESHORE EVEN
HIGHER GUSTS WILL BE POSSIBLE...IN THE 40-50 MPH RANGE. THE
COMBINATION OF THE WINDS AND FALLING SNOW WILL PRODUCE VERY LOW
VISIBILITIES WITH NEAR WHITEOUT CONDITIONS AT TIMES IN OPEN/EXPOSED
AREAS. THE BLOWING SNOW/VISIBILITY HAZARD WAS ENOUGH TO JUSTIFY UPGRADE
OF MARQUETTE-BAGARAG WINTER WEATHER ADVISORIES TO WINTER STORM
WARNINGS EVEN WITH RELATIVELY MODEST ADDITIONAL SNOW AMOUNTS.
A TRANSITION FROM LAKE ENHANCED CLOSER TO PURE LAKE EFFECT SNOW IS
EXPECTED FROM THIS AFTERNOON INTO TONIGHT AS THE SYNOPTIC SCALE LIFT
WEAKENS AND DEPARTS TO THE EAST. THE GRADIENT WILL ALSO ONLY
GRADUALLY WEAKEN...KEEPING THE THREAT OF BLSN GOING. ADDITIONAL
AMONTS IN THE 1 TO 4 INCH RANGE NORTH ARE EXPECTED WITH LCLY HIGHER
AMOUNTS IN THE 4 TO 7 INCH RANGE POSSIBLE FROM FAR ERN MARQUETTE
COUNTY INTO ALGER COUNTY.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 539 AM EST TUE FEB 19 2013
LOW PRESSURE OVER LOWER LAKES BEGINS TO UNRAVEL ON WEDNESDAY AS
UPPER TROUGH SURGES EAST WITH MAIN JET ENERGY OUT AHEAD OF TROUGH
VERSUS DIGGING INTO THE BACK SIDE OF THE TROUGH. CYCLONIC FLOW
STEADILY WEAKENS THROUGH THE DAY AND H8-H7 MOISTURE WILL BE ON THE
DOWNWARD TREND. EXPECT VIGOROUS LK ENHANCED SNOW TO BEGIN THE DAY TO
FADE BY LATE AFTN/EARLY WED EVENING. ADDITIONAL SNOW AMOUNTS
WEDNESDAY SHOULD BE IN THE MORE MODERATE RANGE AS NEGATIVE FACTORS
PUT CRIMP IN LK EFFECT INSENSITY THROUGH THE DAY. NNW WINDS GUSTING
OVER 30 MPH RESULT IN MORE BLSN/REDUCED VSBY FOR MAINLY EASTERN AREAS
BUT THIS TOO WILL IMPROVE BY WEDNESDAY EVENING. ORIGINALLY THOUGHT
THE 00Z THU EXPIRATION TIME OF WARNING WAS TOO LONG...BUT DUE TO
ONLY A GRADUAL DECREASING TREND IN SNOW/WIND...IT APPEARS IN GOOD
SHAPE.
1040MB HIGH PRESSURE OVER ONTARIO SLIDES BY INTO WESTERN QUEBEC
THROUGH THURSDAY NIGHT. RESULT IS WEAK NORTH TO NORTHEAST WINDS AT
SFC THROUGH 925MB. INVERSION LESS THAN 3KFT EASILY...BUT STILL ENOUGH
OVER-WATER INSTABILITY IN MOIST LAYER TO KEEP SMALL CHANCES FOR LK
EFFECT GOING OVR NCNTRL UPR MICHIGAN OVERNIGHT WED NIGHT THROUGH THU
MORNING. LOW-LEVEL WINDS BECOMES DIFFLUENT OVR WEST ENOUGH TO BREAK
UP LINGERING CLOUDS EVEN AS 925MB WINDS REMAIN ONSHORE. MIN TEMPS
OVR INTERIOR WEST PROBABLY END UP BLO ZERO. SINGLE DIGITS TO LOWER
TEENS ABOVE ZERO ELSEWHERE.
MODELS INSISTENT ON SHOWING SHARP SOUTHERN STREAM SHORTWAVE TROUGH
LIFTING THROUGH MID MISSISSIPPI AND LOWER MISSOURI RIVER VALLEY ON
THURSDAY AND INTO UPR GREAT LAKES ON FRIDAY. SYSTEM EXPECTED TO LOSE
BIG PART OF ITS PUNCH FROM THE HEAVY SNOW THAT IS FORECAST OVER
CNTRL PLAINS ON THURSDAY BY TIME IT REACHES UPR LAKES. DIMINISHING
TREND MOSTLY DUE TO DECREASING MOISTURE AS H7 MIXING RATIOS OVER
4G/KG ARE SHUNTED MORE INTO TENNESSEE RIVER AND OHIO RIVER VALLEYS
WITH MIXING RATIOS LESS THAN 2.5G/KG MAKING IT INTO UPR MICHIGAN.
SYSTEM IS ALSO RUNNING INTO RIDGING ALOFT. ENOUGH CONFIDENCE IT WILL
SNOW OVER SOUTH CWA TO INCREASE POPS TO LIKELY. COORD WITH DLH/GRB
ON THIS. CHANCE POPS ELSEWHERE WITH INDICATION THERE MAY BE SHARP
CUTOFF TO NORTHERN EDGE OF SNOW. LINGERING SFC-H5 TROUGH SLIDES
ACROSS UPR LAKES THROUGH SATURDAY...SO KEPT SMALL CHANCES IN THE
FORECAST. NO BIG ORGANIZED SNOWS ARE IN STORE THOUGH...JUST PATCHY
SNOW AND/OR SNOW SHOWERS. TEMPS WILL BE WARMING WITH DAYTIME HIGHS
BOTH SATURDAY AND SUNDAY POSSIBLY PUSHING PAST 30 DEGREES.
HIGH PRESSURE BUILDS IN TO CLOSE THE WEEKEND THEN ANOTHER SOUTHERN
STREAM SYSTEM MAY TAKE AIM ON UPR MICHIGAN EARLY NEXT WEEK. RIGHT
NOW THAT SYSTEM LOOKS TO HAVE SIMILAR EVOLUTION AS ONE MOVING
THROUGH ON FRIDAY. WE SHALL SEE. MODEL TIMING ISSUES EVIDENT FOR THE
ARRIVAL OF SNOW SO USED CONSENSUS POPS AT THIS POINT. WITH SOUTHERN
STREAM ORIGIN...TEMPERATURES WILL LIKELY BE AT OR ABOVE NORMAL FOR
NEXT WEEKEND.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 717 AM EST TUE FEB 19 2013
CMX...EXPECT PREDOMINANT VLIFR CONDITIONS AS VERY STRONG NNW WINDS
COMBINE WITH LAKE ENHANCED SNOW TO PRODUCE NEAR BLIZZARD CONDITIONS
AT TIMES FOR MUCH OF TODAY. THE WINDS MAY DIMINISH ENOUGH THIS
EVENING FOR SOME IMPROVEMENT WITH LIFR/IFR CONDITIONS.
SN/BLSN WILL ALSO KEEP MAINLY IFR/LIFR CONDITIONS AT IWD.
HOWEVER...THERE MAY BE SOME IMPROVEMENT LATER TODAY AS THE WINDS
SLOWLY DIMINISH ONCE THE LO SHIFTS FARTHER TO THE E.
SAW...EXPECT PREDOMINANT IFR/LIFR CONDITIONS. AS THE LOW PULLS OFF
TO THE E LATER TONIGHT AND INTENSIFIES...THE COMBINATION OF FALLING
SN/BLSN FROM AN INCREASING NW WIND WILL CAUSE LIFR CONDITIONS THRU THE
MRNG. THERE MAY BE SOME IMPROVEMENT IN THE AFTERNOON ONCE THE DEEPER
MOISTURE EXITS AND THE DOWNSLOPE FLOW HELPS REDUCE THE SNOW
INTENSITY. HOWEVER...GUSTY WINDS/BLSN MAKE IFR CONDITIONS LIKELY
THROUGH THIS EVENING.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 539 AM EST TUE FEB 19 2013
STRONG WRAPPED UP SFC LOW NEARS STRAITS THIS MORNING AND HEADS
TOWARD WESTERN QUEBEC TONIGHT WHILE BEGINNING TO WEAKEN. MSLP AS LOW
AS 986MB THIS MORNING. VERY TIGHT PRESSURE GRADIENT PRESENT THROUGH
THIS EVENING FROM SSM TO DLH...POSSIBLY EXCEEDING AN IMPRESSIVE 25
MB INTO THE AFTN. SUCH A STRONG GRADIENT COMBINED WITH COLD AIR
ADVECTION AND STRONG WINDS ALOFT LEAD TO STRONG GALES WITH FREQUENT
STORM FORCE GUSTS OVER CNTRL LK SUPERIOR. CURRENT STORM AND GALE
WARNINGS IN FINE SHAPE. WINDS WILL BE SLOW TO DIMINISH WITH GALES
PERSISTING OVER LK SUPERIOR THROUGH WED. HEAVY FREEZING SPRAY WILL
CONTINUE THROUGH THURSDAY MORNING. HIGH PRESSURE CROSSING ON
THURSDAY WILL ALLOW WINDS TO RELAX AND HEAVY FREEZING SPRAY TO
SUBSIDE. EXPECT EAST WINDS 20-30 KTS ON FRIDAY INTO FRIDAY NIGHT
AS LOW PRESSURE MOVES IN FROM THE CENTRAL PLAINS. WINDS FOR THE
UPCOMING WEEKEND NO MORE THAN 20 KTS AS WEAK PRESSURE GRADIENT
PREVAILS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER STORM WARNING UNTIL MIDNIGHT EST /11 PM CST/ TONIGHT FOR
MIZ002-004-005-009-084.
WINTER STORM WARNING UNTIL 5 PM EST WEDNESDAY FOR MIZ006-007-014-
085.
WINTER STORM WARNING UNTIL 7 AM EST WEDNESDAY FOR MIZ001-003.
WINTER WEATHER ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR MIZ013.
LAKE SUPERIOR...
HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST /6 AM CST/ THURSDAY
FOR LSZ162-240>251-263>267.
GALE WARNING UNTIL 7 PM EST WEDNESDAY FOR LSZ245>251-265-267.
STORM WARNING UNTIL 7 PM EST THIS EVENING FOR LSZ266.
STORM WARNING UNTIL 1 PM EST THIS AFTERNOON FOR LSZ243-244-264.
GALE WARNING UNTIL 5 AM EST /4 AM CST/ WEDNESDAY FOR LSZ240>242-
263.
GALE WARNING UNTIL 1 PM EST /NOON CST/ THIS AFTERNOON FOR LSZ162.
LAKE MICHIGAN...
GALE WARNING UNTIL 7 AM EST WEDNESDAY FOR LMZ248-250.
&&
$$
SHORT TERM...JLB
LONG TERM...JLA
AVIATION...JLB
MARINE...JLA
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
543 AM EST TUE FEB 19 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 539 AM EST TUE FEB 19 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL TROUGH FROM
HUDSON BAY THROUGH NW ONTARIO INTO WI/IL WAS BECOMING MORE
NEGATIVELY TILTED AS A 120 KT 300-250 JET MOVES FROM THE OHIO VALLEY
TOWARD THE EASTERN LAKES. THE BACK EDGE OF A WELL-DEFINED WARM
CONVEYOR SHIELD EXTENDED FROM NEAR CMX-DTW. UPPER LEVEL DIV WITH A
COUPLED JET STRUCTURE AND STRONG DEEP LAYER QVECTOR CONV SUPPORTED A
LARGE AREA OF MODERATE SNOW ACROSS LAKE SUPERIOR AND UPPER MI INTO
NRN WI. AT THE SFC...LOW PRES WAS DEEPENING AS IT MOVED THROUGH NRN
LAKE SUPERIOR AND AT 10Z WAS AROUND 987 MB NEAR BEAVER ISLAND. THE
TIGHTENING GRADIENT BETWEEN THE LOW AND A 1040 MB RIDGE OVER
MANITOBA INTO THE NRN PLAINS HAS RESULTED IN VERY GUSTY WINDS WITH
P59 ALREADY RECORDING GUSTS TO 49 MPH. RELATIVELY LOW SLR VALUES
NEAR 10/1 AND THE STRONG WINDS FRACTURING SNOW FLAKES HAVE KEPT SNOW
AMOUNTS GENERALLY IN THE 2 TO 3 INCH RANGE.
THE MODERATE TO STRONG 700-300 QVECTOR CONV AND FAVORABLE 280K-290K
ISENTROPIC LIFT INTO CNTRL AND EAST UPPER MICHIGAN WILL CONTINUE
WITH WIDESPEAD SYNOPTIC SNOW CONTINUING. ADDITIONAL SYNOPTIC QPF
VALUES OF AROUND 0.10 TO 0.20 INTO THE NRN CWA SHOULD PROVIDE
POTENTIAL FOR AN ADDITIONAL 1 TO 3 INCHES. LOW LEVEL CAA WITH 850 MB
TEMPS DROPPING INTO THE -15C TO -17C RANGE WILL BRING ADDITIONAL
LAKE ENHANCED SNOW FOR LOCATIONS FAVORED BY CYCLONIC 340-330 FLOW.
THIS WOULD AFFECT MOST OF NORTHERN UPPER MICHIGAN WITH LOW LEVEL
CONV FOCUSED NEAR THE MARQUETTE COUNTY SHORLINE AND INTO WRN ALGER
COUNTY. ADDITIONAL AMOUNTS FROM LAKE ENHANCED SNOW OF 1 TO 3 INCHES
ARE ALSO EXPECTED.
THE MAIN HAZARD HOWEVER...WILL BE THE VERY STRONG WINDS AS MODEL
MOMENTUMM TRANSFER PROFILES SUGGEST THAT WINDS WILL GUST IN THE
30-40 MPH RANGE...ESPECIALLY THIS MORNING. ALONG THE LAKESHORE EVEN
HIGHER GUSTS WILL BE POSSIBLE...IN THE 40-50 MPH RANGE. THE
COMBINATION OF THE WINDS AND FALLING SNOW WILL PRODUCE VERY LOW
VISIBILITIES WITH NEAR WHITEOUT CONDITIONS AT TIMES IN OPEN/EXPOSED
AREAS. THE BLOWING SNOW/VISIBILITY HAZARD WAS ENOUGH TO JUSTIFY UPGRADE
OF MARQUETTE-BAGARAG WINTER WEATHER ADVISORIES TO WINTER STORM
WARNINGS EVEN WITH RELATIVELY MODEST ADDITIONAL SNOW AMOUNTS.
A TRANSITION FROM LAKE ENHANCED CLOSER TO PURE LAKE EFFECT SNOW IS
EXPECTED FROM THIS AFTERNOON INTO TONIGHT AS THE SYNOPTIC SCALE LIFT
WEAKENS AND DEPARTS TO THE EAST. THE GRADIENT WILL ALSO ONLY
GRADUALLY WEAKEN...KEEPING THE THREAT OF BLSN GOING. ADDITIONAL
AMONTS IN THE 1 TO 4 INCH RANGE NORTH ARE EXPECTED WITH LCLY HIGHER
AMOUNTS IN THE 4 TO 7 INCH RANGE POSSIBLE FROM FAR ERN MARQUETTE
COUNTY INTO ALGER COUNTY.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 539 AM EST TUE FEB 19 2013
LOW PRESSURE OVER LOWER LAKES BEGINS TO UNRAVEL ON WEDNESDAY AS
UPPER TROUGH SURGES EAST WITH MAIN JET ENERGY OUT AHEAD OF TROUGH
VERSUS DIGGING INTO THE BACK SIDE OF THE TROUGH. CYCLONIC FLOW
STEADILY WEAKENS THROUGH THE DAY AND H8-H7 MOISTURE WILL BE ON THE
DOWNWARD TREND. EXPECT VIGOROUS LK ENHANCED SNOW TO BEGIN THE DAY TO
FADE BY LATE AFTN/EARLY WED EVENING. ADDITIONAL SNOW AMOUNTS
WEDNESDAY SHOULD BE IN THE MORE MODERATE RANGE AS NEGATIVE FACTORS
PUT CRIMP IN LK EFFECT INSENSITY THROUGH THE DAY. NNW WINDS GUSTING
OVER 30 MPH RESULT IN MORE BLSN/REDUCED VSBY FOR MAINLY EASTERN AREAS
BUT THIS TOO WILL IMPROVE BY WEDNESDAY EVENING. ORIGINALLY THOUGHT
THE 00Z THU EXPIRATION TIME OF WARNING WAS TOO LONG...BUT DUE TO
ONLY A GRADUAL DECREASING TREND IN SNOW/WIND...IT APPEARS IN GOOD
SHAPE.
1040MB HIGH PRESSURE OVER ONTARIO SLIDES BY INTO WESTERN QUEBEC
THROUGH THURSDAY NIGHT. RESULT IS WEAK NORTH TO NORTHEAST WINDS AT
SFC THROUGH 925MB. INVERSION LESS THAN 3KFT EASILY...BUT STILL ENOUGH
OVER-WATER INSTABILITY IN MOIST LAYER TO KEEP SMALL CHANCES FOR LK
EFFECT GOING OVR NCNTRL UPR MICHIGAN OVERNIGHT WED NIGHT THROUGH THU
MORNING. LOW-LEVEL WINDS BECOMES DIFFLUENT OVR WEST ENOUGH TO BREAK
UP LINGERING CLOUDS EVEN AS 925MB WINDS REMAIN ONSHORE. MIN TEMPS
OVR INTERIOR WEST PROBABLY END UP BLO ZERO. SINGLE DIGITS TO LOWER
TEENS ABOVE ZERO ELSEWHERE.
MODELS INSISTENT ON SHOWING SHARP SOUTHERN STREAM SHORTWAVE TROUGH
LIFTING THROUGH MID MISSISSIPPI AND LOWER MISSOURI RIVER VALLEY ON
THURSDAY AND INTO UPR GREAT LAKES ON FRIDAY. SYSTEM EXPECTED TO LOSE
BIG PART OF ITS PUNCH FROM THE HEAVY SNOW THAT IS FORECAST OVER
CNTRL PLAINS ON THURSDAY BY TIME IT REACHES UPR LAKES. DIMINISHING
TREND MOSTLY DUE TO DECREASING MOISTURE AS H7 MIXING RATIOS OVER
4G/KG ARE SHUNTED MORE INTO TENNESSEE RIVER AND OHIO RIVER VALLEYS
WITH MIXING RATIOS LESS THAN 2.5G/KG MAKING IT INTO UPR MICHIGAN.
SYSTEM IS ALSO RUNNING INTO RIDGING ALOFT. ENOUGH CONFIDENCE IT WILL
SNOW OVER SOUTH CWA TO INCREASE POPS TO LIKELY. COORD WITH DLH/GRB
ON THIS. CHANCE POPS ELSEWHERE WITH INDICATION THERE MAY BE SHARP
CUTOFF TO NORTHERN EDGE OF SNOW. LINGERING SFC-H5 TROUGH SLIDES
ACROSS UPR LAKES THROUGH SATURDAY...SO KEPT SMALL CHANCES IN THE
FORECAST. NO BIG ORGANIZED SNOWS ARE IN STORE THOUGH...JUST PATCHY
SNOW AND/OR SNOW SHOWERS. TEMPS WILL BE WARMING WITH DAYTIME HIGHS
BOTH SATURDAY AND SUNDAY POSSIBLY PUSHING PAST 30 DEGREES.
HIGH PRESSURE BUILDS IN TO CLOSE THE WEEKEND THEN ANOTHER SOUTHERN
STREAM SYSTEM MAY TAKE AIM ON UPR MICHIGAN EARLY NEXT WEEK. RIGHT
NOW THAT SYSTEM LOOKS TO HAVE SIMILAR EVOLUTION AS ONE MOVING
THROUGH ON FRIDAY. WE SHALL SEE. MODEL TIMING ISSUES EVIDENT FOR THE
ARRIVAL OF SNOW SO USED CONSENSUS POPS AT THIS POINT. WITH SOUTHERN
STREAM ORIGIN...TEMPERATURES WILL LIKELY BE AT OR ABOVE NORMAL FOR
NEXT WEEKEND.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1255 AM EST TUE FEB 19 2013
IWD/CMX...EXPECT PREDOMINANT IFR CONDITIONS AT TAF ISSUANCE WITH -SN
FALLING TO GIVE WAY TO LIFR/PERHAPS VLIFR WX EARLY THIS MRNG THRU
MUCH OF TODAY AS THE ARRIVAL OF MUCH COLDER AIR ON THE HEELS OF VERY
GUSTY NW WINDS CAUSES LK ENHANCED SN/EXTENSIVE BLSN...WITH NEAR
BLIZZARD CONDITIONS AT TIMES IN THESE LOCATIONS EXPOSED TO NW WIND.
IWD IS LIKELY TO SEE SOME IMPROVEMENT LATER TODAY AS THE WINDS
SLOWLY DIMINISH ONCE THE LO SHIFTS FARTHER TO THE E.
SAW...EXPECT PREDOMINANT IFR/LIFR CONDITIONS EARLY THIS MRNG AS AREA
OF SN ASSOCIATED WITH LO PRES MOVING THRU THE UPR LKS IMPACTS THIS
LOCATION. AS THE LO PULLS OFF TO THE E LATER TNGT AND INTENSIFIES...
THE COMBINATION OF FALLING SN/BLSN FROM AN INCRSG NW WIND WL CAUSE
LIFR CONDITIONS THRU THE MRNG. THERE MAY BE SOME IMPROVEMENT IN THE
AFTN ONCE THE DEEPER MSTR EXITS AND THE DOWNSLOPE FLOW EASES THE
PCPN INTENSITY. BUT GUSTY WINDS/BLSN MAKE IFR CONDITIONS LIKELY THRU
THIS EVNG.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 539 AM EST TUE FEB 19 2013
STRONG WRAPPED UP SFC LOW NEARS STRAITS THIS MORNING AND HEADS
TOWARD WESTERN QUEBEC TONIGHT WHILE BEGINNING TO WEAKEN. MSLP AS LOW
AS 986MB THIS MORNING. VERY TIGHT PRESSURE GRADIENT PRESENT THROUGH
THIS EVENING FROM SSM TO DLH...POSSIBLY EXCEEDING AN IMPRESSIVE 25
MB INTO THE AFTN. SUCH A STRONG GRADIENT COMBINED WITH COLD AIR
ADVECTION AND STRONG WINDS ALOFT LEAD TO STRONG GALES WITH FREQUENT
STORM FORCE GUSTS OVER CNTRL LK SUPERIOR. CURRENT STORM AND GALE
WARNINGS IN FINE SHAPE. WINDS WILL BE SLOW TO DIMINISH WITH GALES
PERSISTING OVER LK SUPERIOR THROUGH WED. HEAVY FREEZING SPRAY WILL
CONTINUE THROUGH THURSDAY MORNING. HIGH PRESSURE CROSSING ON
THURSDAY WILL ALLOW WINDS TO RELAX AND HEAVY FREEZING SPRAY TO
SUBSIDE. EXPECT EAST WINDS 20-30 KTS ON FRIDAY INTO FRIDAY NIGHT
AS LOW PRESSURE MOVES IN FROM THE CENTRAL PLAINS. WINDS FOR THE
UPCOMING WEEKEND NO MORE THAN 20 KTS AS WEAK PRESSURE GRADIENT
PREVAILS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER STORM WARNING UNTIL MIDNIGHT EST /11 PM CST/ TONIGHT FOR
MIZ002-004-005-009-084.
WINTER STORM WARNING UNTIL 5 PM EST WEDNESDAY FOR MIZ006-007-014-
085.
WINTER STORM WARNING UNTIL 7 AM EST WEDNESDAY FOR MIZ001-003.
WINTER WEATHER ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR MIZ013.
LAKE SUPERIOR...
HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST /6 AM CST/ THURSDAY
FOR LSZ162-240>251-263>267.
GALE WARNING UNTIL 7 PM EST WEDNESDAY FOR LSZ245>251-265-267.
STORM WARNING UNTIL 7 PM EST THIS EVENING FOR LSZ266.
STORM WARNING UNTIL 1 PM EST THIS AFTERNOON FOR LSZ243-244-264.
GALE WARNING UNTIL 5 AM EST /4 AM CST/ WEDNESDAY FOR LSZ240>242-
263.
GALE WARNING UNTIL 1 PM EST /NOON CST/ THIS AFTERNOON FOR LSZ162.
LAKE MICHIGAN...
GALE WARNING UNTIL 7 AM EST WEDNESDAY FOR LMZ248-250.
&&
$$
SHORT TERM...JLB
LONG TERM...JLA
AVIATION...KC
MARINE...JLA
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
347 AM EST TUE FEB 19 2013
.SHORT TERM... TODAY AND TONIGHT
MILD AND WET CONDITIONS THROUGHOUT SE MICHIGAN DURING THE EARLY
MORNING WILL BE KICKED OUT OF THE AREA BY A STRONG COLD FRONT
PASSING THROUGH AROUND SUNRISE. THE MAIN CONCERN WITH THIS FRONT
WILL BE PEAK WIND GUSTS REACHING 45 MPH ADVISORY CRITERIA IN THE
STRONG WESTERLY FLOW BEHIND IT, BUT THE COMBINATION OF FALLING
TEMPERATURES AND SNOW SHOWERS WILL ALSO ADD A LAYER OF HARSHNESS TO
CONDITIONS THROUGH THE DAY. EXPECT TEMPERATURES TO FALL TOWARD THE
MID AND UPPER 20S BY LATE MORNING, STRUGGLE TO REMAIN IN THE 20S
DURING THE AFTERNOON WITH SINGLE DIGIT WIND CHILL, AND THEN GIVE WAY
TO LOWS WELL DOWN INTO THE TEENS TONIGHT WITH WIND CHILL ABOUT 5
BELOW AFTER MIDNIGHT.
UPSTREAM OBSERVATIONS, ALONG WITH MODEL ISALLOBARIC FIELDS, INDICATE
THE STRONGEST WIND GUSTS OF 40 TO 50 KNOTS OVER CENTRAL INDIANA
OCCURRED WITHIN THE STEEPEST ISALLOBARIC GRADIENT ASSOCIATED WITH A
PEAK 3 HOUR PRESSURE RISE STARTING OFF CLOSE TO 10 MB. THIS PRESSURE
RISE CENTER IS SHOWN TO WEAKEN FROM NEARLY 10 MB TO 3-4 MB IN THE
NAM12 AND HIGH RES RAP MODELS AS THE FRONT MOVES THROUGH WESTERN
LOWER MICHIGAN AND THE REST OF INDIANA AND OHIO. THIS WEAKENING OF
THE ISALLOBARIC COMPONENT OF DYNAMIC FORCING WILL LIKELY RESULT IN A
SHORTER DURATION OF PEAK GUSTS AROUND 45 MPH IN OUR AREA ALONG AND
IMMEDIATELY POST FRONT. AFTER THAT, EXPECT A FEW HOURS OF WIND GUSTS
LESS THAN 40 MPH UNTIL COLD ADVECTION AND SYSTEM RELATIVE ISENTROPIC
DESCENT RAMPS UP LEADING TO STEEPENING LAPSE RATES IN A DEEPENING
BOUNDARY LAYER. DOWNWARD MOMENTUM TRANSPORT WILL THEN BE SUFFICIENT
FOR GUSTS TO REACH 45 MPH AGAIN BY LATE MORNING THROUGH THE
AFTERNOON. GUSTS WILL DIMINISH BY TONIGHT BUT WILL REMAIN IN THE 30
MPH RANGE AS THE BOUNDARY LAYER REMAINS WELL MIXED AFTER SUNSET.
AFTER THE DRY SLOT KEEPS SNOW AT BAY DURING THE MORNING, AN
EXPANSIVE AREA OF MID LEVEL MOISTURE WRAPPING AROUND THE WESTERN
FLANK OF THE LOW WILL DRIVE THE PATTERN OF SNOW DURING THE AFTERNOON
THROUGH TONIGHT. EARLY MORNING RADAR COMPOSITES SHOW THIS COMING
TOGETHER OVER THE UPPER MIDWEST AT PRESS TIME ADDING CONFIDENCE TO
THE EXPECTATION OF A HIGH POP/LOW ACCUMULATION SCENARIO. THIS
MOISTURE WILL SEED ENHANCEMENT FROM LAKE MICHIGAN AS INSTABILITY
INCREASES INTO THE 15-20C RANGE FOR LAKE TO 850 MB DELTA-T. THE MAIN
LIMITING FACTOR WILL BE THE STRONG WIND SPEED AND STEADY VEERING
TREND THAT WILL PREVENT ANY DOMINANT BAND FORMATION. PLAN TO FAVOR
THE TRI CITIES AND THUMB WITH CATEGORICAL POPS DURING THE AFTERNOON
AND LIKELY INTO THE THE EVENING WITH 1 TO 2 INCHES OF ACCUMULATION
BEFORE THE WIND SHIFT TOWARD THE NORTHWEST FAVORS AREAS SOUTH OF
INTERSTATE 69 TOWARD SUNRISE WEDNESDAY.
&&
.LONG TERM...
ALTHOUGH THE 500 MB LOW/MID LEVEL COLD POOL WILL BE MOVING INTO NEW
ENGLAND ON WEDNESDAY...A SHALLOW (SFC-925 MB) BACK DOOR COLD FRONT
WILL ATTEMPT TO MAKE INROADS INTO SOUTHERN LOWER MICHIGAN.
925 MB TEMPS OF -16 TO -17 C FORECASTED TO WORK THROUGH THE THUMB
REGION...WITH LOW LEVEL FLOW JUST SLIGHTLY WEST OF DUE NORTH.
SO...REASONABLE EXPECTATION SOME LAKE EFFECT SNOW SHOWER ACTIVITY
WILL BRUSH THE SHORELINE...BUT SHALLOW NATURE OF THE ACTIVITY
(MODERATING 850 MB TEMPS) SHOULD PREVENT ACTIVITY FROM GETTING OUT
OF HAND. 1042 MB HIGH OVER ONTARIO WILL NOSE INTO SOUTHEAST MICHIGAN
ON THURSDAY...AS AMPLIFIED UPPER LEVEL RIDGE MOVES OVER THE WESTERN
GREAT LAKES. POTENT UPPER WAVE JUST OFF THE PACIFIC NORTHWEST COAST
EARLY THIS MORNING STILL PROGGED TO ROTATE THROUGH THE FOUR CORNERS
REGION LATE WEDNESDAY...BUT TRACKING JUST A TOUCH FARTHER
EAST...OVER/NEAR SIOUX FALLS SOUTH DAKOTA THURSDAY NIGHT (PER 00Z
GFS/EURO). DRAMATIC WEST-EAST SHEARING OF THE UPPER LEVEL
CIRCULATION WILL OCCUR...BUT STILL A PERIOD OF LARGE SCALE ASCENT/PV
ADVECTION FRIDAY MORNING TO OCCUR OVER SOUTHEAST MICHIGAN. THE BULK
OF THE LIFT WILL BE USED UP JUST TO SATURATE THE LOW LEVELS...AS THE
PREVIOUSLY MENTIONED HIGH OVER ONTARIO LEADS TO EASTERLY DRY LOW
LEVEL FLOW PERSISTING INTO FRIDAY. 00Z GFS NOT EVEN GIVING US A
TENTH OF AN INCH OF QPF...AS DEEPER MOISTURE SEEN IN THE 850-700
MB/PW FIELDS SKIRTS JUST TO THE SOUTHEAST OF THE CWA. STILL...DECENT
SHOT OF MOISTURE ADVECTION...AND PREFERENCE IS WITH THE STRONGER
CANADIAN/EURO WHICH MAINTAINS THE 500 MB LOW OVER MINNESOTA INTO THE
FIRST HALF OF THE WEEKEND. QPF FROM THOSE MODELS SUPPORTS A SOLID 1
TO TWO INCHES OF SNOW ON FRIDAY...WITH RELATIVELY LOW SNOW TO LIQUID
RATIOS...AS ZERO OR SLIGHTLY BETTER 850 MB TEMPS SEEN REACHING THE
OHIO BORDER.
THE MODEST MID LEVEL COLD POOL OVER MINNESOTA WILL BREAK OFF TO THE
EAST FOR THE WEEKEND...KEEPING TEMPERATURES IN CHECK...AS 850 MB
TEMPS LOOK TO BE HOVERING AROUND -10 C...AND WITH LIMITED
SUNSHINE...MAXES EXPECTED TO REMAIN GENERALLY BELOW 40 DEGREES.
ALTHOUGH...WE WILL HAVE THE DRY SLOT WORKING THROUGH SATURDAY
MORNING...WHICH COULD BE THE DAY WE SNEAK UP TO 40 DEGREES.
&&
.MARINE...
DEEP LOW PRESSURE MOVING THROUGH THE STRAITS WILL PULL A STRONG COLD
FRONT THROUGH LAKE HURON AND LOWER MICHIGAN EARLY IN THE MORNING.
WESTERLY GALES WILL DEVELOP AFTER THE FRONTAL PASSAGE AND THEN
PERSIST TONIGHT THROUGH WEDNESDAY WHILE VEERING TO NORTHWEST OVER
THE OPEN WATERS OF LAKE HURON. POLAR AIR SURGING BACK INTO THE
REGION WILL CHANGE RAIN BACK TO SNOW AND ALSO LEAD TO A SUBSTANTIAL
FREEZING SPRAY HAZARD OVER THE OPEN WATERS TONIGHT THROUGH
WEDNESDAY. THE STRONG WINDS AND RESULTING LARGE WAVES WILL COMBINE
WITH NEAR IDEAL WATER TEMPERATURE FOR WIDESPREAD FREEZING SPRAY TO
BECOME HEAVY. MARINE CONDITIONS WILL THEN IMPROVE CONSIDERABLY BY
THURSDAY AS HIGH PRESSURE SETTLES OVER THE REGION.
&&
.AVIATION...ISSUED 1150 PM EST MON FEB 18 2013
//DISCUSSION...
RAIN SHOWERS WILL BECOME MORE NUMEROUS AS THIS FORECAST PERIOD
BEGINS AS MOISTURE CONVERGENCE IN ADVANCE OF APPROACHING COLD FRONT
SHIFT INTO THE AREA. WITH THIS ACTIVITY...CIGS WILL FALL TO MVFR TO
OCCASIONAL IFR...ESPECIALLY RIGHT ALONG THE FRONT...WHICH WILL PASS
THROUGH BETWEEN 10Z-12Z. RAIN SHOWERS WILL CHANGE TO SNOW WITHIN
COLD AIR ADVECTION BEHIND THE FRONT...AND WEST/SOUTHWEST WINDS WILL
BECOME VERY STRONG WITH GUSTS TO 30-35 KNOTS ON TUESDAY.
FOR DTW...CIGS WILL FALL BELOW 5000 FEET AT THE BEGINNING OF THE
FORECAST AND THEN BOTTOM OUT BETWEEN 900-1800 FEET IN ADVANCE OF
COLD FRONT BEFORE LIFTING BACK TO MVFR/LOWER VFR ON TUESDAY AS GUSTY
(25-35 KT) WEST/SOUTHWEST FLOW DEVELOPS. RAIN SHOWERS TONIGHT
WILL CHANGE TO SCATTERED LIGHT SNOW SHOWERS.
//DTW THRESHOLD THREATS...
* HIGH CONFIDENCE IN CEILING BELOW 5000 FEET MUCH OF THE FORECAST.
* HIGH CONFIDENCE IN RAIN AS PRECIPITATION TYPE TONIGHT...CHANGING
TO SNOW SHOWERS AROUND 11Z-12Z TUESDAY.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...WIND ADVISORY...MIZ047-MIZ048-MIZ049-MIZ053-MIZ054-MIZ055-MIZ060-
MIZ061-MIZ062-MIZ063-MIZ068-MIZ069-MIZ070-MIZ075-MIZ076-MIZ082-
MIZ083...UNTIL 7 PM TUESDAY.
LAKE HURON...
GALE WARNING...LHZ361...FROM NOON TUESDAY TO 7 PM WEDNESDAY.
HEAVY FREEZING SPRAY WARNING...LHZ361-LHZ362-LHZ363-LHZ462-LHZ463-
LHZ464...FROM 7 PM TUESDAY TO 7 PM WEDNESDAY.
GALE WARNING...LHZ362-LHZ363...FROM 7 AM TUESDAY TO 7 PM WEDNESDAY.
GALE WARNING...LHZ421-LHZ422-LHZ441-LHZ442-LHZ443-LHZ462-LHZ463-
LHZ464...FROM 7 AM TUESDAY TO MIDNIGHT WEDNESDAY.
LAKE ST CLAIR...
GALE WARNING...FROM 7 AM TUESDAY TO MIDNIGHT WEDNESDAY.
MI WATERS OF LAKE ERIE...
GALE WARNING...FROM 7 AM TUESDAY TO MIDNIGHT WEDNESDAY.
&&
$$
SHORT TERM...BT
LONG TERM....SF
MARINE.......BT
AVIATION.....DG
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS DULUTH MN
1233 PM CST TUE FEB 19 2013
.UPDATE...LET WIND CHILL ADVISORY EXPIRE AT SCHEDULED TIME SINCE
MOST LOCATIONS ACROSS OUR CWA HAVE WARMED ABOVE ADVISORY
THRESHOLD. MADE SOME MINOR ADJUSTMENTS TO POPS AND WX AS WELL FOR
THE LAKE EFFECT SNOW EVENT ALONG THE SOUTHSHORE. OTHERWISE GOING
FCST LOOKS GOOD.
&&
.PREV DISCUSSION... /ISSUED 1127 AM CST TUE FEB 19 2013/
AVIATION...../18Z TAF ISSUANCE/
MAINLY VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD. THE ONLY
EXCEPTION WILL BE HIB WHERE SOME BLOWING SNOW WILL BRING SOME MVFR
VISIBILITIES FOR SEVERAL HOURS THIS AFTERNOON. THE GUSTY NORTH TO
NORTHWESTERLY WINDS WILL DIMINISH THIS EVENING. SKIES WILL BE MOSTLY
CLEAR THROUGHOUT THIS TAF FORECAST PERIOD. EXPECT LIGHT WINDS FROM
THE NORTHEAST BY THE END OF THIS TAF FORECAST PERIOD.
PREV DISCUSSION... /ISSUED 321 AM CST TUE FEB 19 2013/
CURRENT...VERY DEEP MID LVL TROF CONTINUES TO AMPLIFY AS IT CRAWLS
ACROSS CWA EARLY THIS MORNING. SFC LOW OVER ERN WISC IS INTENSIFYING
AS IT MOVES TOWARDS ERN END OF LAKE SUPERIOR. LARGE SHIELD OF DEEP
LAYER MOISTURE ACCOMPANIED BY COLD ADVECTION IS KEEPING LIGHT SNOW
ACROSS REGION. A STANDING WAVE IS INDICATED... ACROSS DOUGLAS COUNTY
AND INTO SE CARLTON COUNTY NEAR HOLYOKE... IN THE ANIMATED 88D
REFL/VEL PRODUCTS AS NW FLOW INCREASES. SFC PRESS GRADIENT NEARLY
20MB ACROSS CWA WITH GUSTY WINDS ACROSS MOST OF MN ZONES. VERY
STRONG GUSTS ALONG NORTH SHORE FROM TWIN PORTS TO GRAND PORTAGE.
LOCAL KATABATIC ENHANCEMENT OCCURING FROM SILVER BAY NORTH TO BORDER
WHERE INLAND TERRAIN IS HIGHER. GUST OVER 50 MPH HAVE OCCURED IN
THIS CORRIDOR WITH HRRR 3KM OUTPUT SUGGESTING GUSTS MAY REACH 60 MPH
THROUGH EARLY MORNING. ARCTIC AIR HAS INFILTRATED THE NORTHWESTERN
CWA WITH SFC TEMPS BELOW ZERO. WINDCHILL ADVISORY MAY NOT VERIFY IN
MANY AREAS UNTIL BETWEEN 12Z-15Z WHEN MIN TEMPS ARE REACHED AND WIND
SPEEDS REMAIN RELATIVELY HIGH. .
TODAY/TONIGHT...SLOW MOVING MID LVL TROF WILL KEEP A CYCLONIC AND
RELATIVELY MOIST CIRCULATION OVER THE REGION. GUSTY WINDS ARE EXPECTD
TO CONTINUE AS SFC PRESS GRADIENT REMAINS QUITE LARGE ACROSS CWA.
BUFKIT MOMENTUM TRANSFER PROFILES SHOW GUSTS MAY LINGER WELL INTO
THE NIGHT AS WELL. NORTH SHORE STILL SUSCEPTIBLE TO KATABATIC
ENHANCEMENT OFF HIGHER PLATEAU WEST OF LAKE SUPERIOR...ESPECIALLY
COOK COUNTY THROUGH MID MORNING. DEEP LAYER DRYING WILL OCCUR FROM
WEST TO EAST TODAY OVER THE MN ZONES. MAIN STORY OVER WISC WILL BE
CONTINUATION OF LES ACROSS SNOW BELTS. LAKE INDUCED CAPE FORECAST
TO INCREASE TO 400/500 J/KG THIS AFTN. INVERSION HEIGHTS ARE
EXPECTED TO LIFT TO ABOUT 4K FT THIS AFTERNOON BEFORE LOWERING TO 2K
FT AFTER MDINIGHT TONIGHT. WILL KEEP CURRENT ADVISORY/WARNING FOR
SOUTH SHORE. WILL NEED ANOTHER WIND CHILL ADVISORY TONIGHT FOR MOST
OF CWA. WILL LET DAY SHIFT ISSUE THIS AFTER CURENT WINDC ADV EXPIRES.
MAX TEMPS TODAY WILL STRUGGLE ALL DAY TO GET ABOVE ZERO ACROSS THE
BORDERLAND AND IRON RANGE. SINGLE DIGITS ELSEWHERE. LOWERED PREVIOUS
TEMP FCST OVER INTERIOR WISC IN LINE WITH ECBC VALUES AND LOWER
TEMPS OF SREF PLUMES.
TOMORROW...PROGRESSIVE FLOW ALOFT WILL SEND A MID LVL RIDGE
OVERHEAD. STRONG SFC HIGH CENTERED OVER NRN ONTARIO WILL BUILD SOUTH
INTO CWA. ABUNDANT SUNSHINE TO START THE DAY ALTHOUGH HIGH CLOUDS
MAY INCREASE FROM THE SOUTHWEST IN THE AFTERNOON IN RESPONSE TO
UPPER LEVEL WARM ADVECTION FROM SRN ROCKIES STORM. TEMPS REMAIN
WELL BELOW CLIMO.
LONG TERM...WEDNESDAY NIGHT THROUGH TUESDAY.
FOCUS IN LONG TERM ON ACTIVE PATTERN FOR THE UPPER MIDWEST LATE IN
THE WEEK...AND EARLY NEXT WEEK.
UPPER LEVEL RIDGE WILL AMPLIFY OVER THE WRN GREAT LAKE REGION WED
NIGHT AS A VORT MAX ROUNDS THE BASE OF A LONG WAVE TROUGH IN THE SW
CONUS...DEEPENING INTO A CLOSED LOW AS IT LIFTS ACROSS THE CENTRAL
PLAINS THURSDAY. THE 00Z MODELS ARE SHOWING GOOD AGREEMENT THAT THE
H50 LOW PUSHES INTO THE SRN DAKOTAS/MINN THURSDAY
EVENING...CENTERING OVER MINNESOTA FRIDAY NIGHT. MEANWHILE...THE SFC
LOW REMAINS TO THE SW OF THE H50 LOW...TRACKING ACROSS IOWA THROUGH
THE DAY FRIDAY...REACHING UPPER MICHIGAN/CEN GREAT LAKES FRIDAY
NIGHT. HAVE MADE VERY LITTLE CHANGES TO POPS THURSDAY NIGHT/FRIDAY
AS THE LEADING EDGE OF THE MAIN SWATH OF SNOW IS EXPECTED TO IMPACT
THE SRN DLH ZONES THURSDAY EVENING...LIFTING OVER MUCH OR ALL OF THE
NORTHLAND THROUGH FRIDAY. TEMPERATURE PROFILES CONTINUE TO SUGGEST
PTYPE OF ALL SNOW FOR THE DLH CWA.
ALTHOUGH UNCERTAINTY REMAINS...MODELS HAVE SHOWN DECENT RUN TO RUN
AGREEMENT THAT A BAND OF HEAVY SNOW DEVELOPS ACROSS THE SRN HALF OF
MINNESOTA THURSDAY NIGHT INTO FRIDAY MORNING. LATEST GFS/ECM
CONTINUE TO SHOW VERY DRY AIR ASSOCIATED WITH A RIDGE AXIS EXTENDING
SOUTH FROM ONTARIO WILL BE DIFFICULT TO ERODE THURSDAY NIGHT...SO
HAVE TRENDED A WITH A SLOWER TIMING FOR INTRODUCING POPS. THE LATEST
NAM BUFR SOUNDING AT KBRD/KINL/KHYR DEPICT PWATS INITIALLY THURSDAY OF
ONLY 0.08". HOWEVER...THERE IS MOISTURE ASSOCIATED WITH THE LOW THAT
DOES ADVECT INTO THE REGION AS THE H50 LOW APPROACHES...ALLOWING
PWATS TO INCREASE TO AROUND 0.3" THROUGH FRIDAY NIGHT AT MOST
LOCATIONS.
HAVE INCREASED TO BROADBRUSH LIKELY POPS FOR LIGHT SNOW FRIDAY.
MODELS SUGGEST THE H50 LOW HANGS AROUND THE GREAT LAKES REGION
THROUGH THE WEEKEND...KEEPING CYCLONIC FLOW...CLOUDS AND LIGHT SNOW
CHANCES FOR THE NORTHLAND.
ALTHOUGH THE GFS IS SHOWING A TREND TOWARDS THE ECM SOLUTION FOR THE
SYSTEM THAT WILL IMPACT THE REGION EARLY NEXT WEEK...THERE REMAINS
LARGE DIFFERENCES IN TIMING AND STORM TRACK. THE ECM SOLUTION LIFTS
THE CLOSED LOW OVER THE DAKOTAS TUESDAY...WHILE THE LATEST GFS
SUGGESTS A FASTER AND MORE EASTERLY TRACK WITH THE H50 LOW PASSING
OVER MINN/WIS MONDAY NIGHT.
&&
.POINT TEMPS/POPS...
DLH -12 13 4 21 / 10 0 0 0
INL -24 8 -11 18 / 10 0 0 0
BRD -14 13 -3 21 / 10 0 0 10
HYR -14 15 -8 24 / 10 0 0 0
ASX -8 15 -1 23 / 50 20 0 0
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...WINTER STORM WARNING UNTIL MIDNIGHT CST TONIGHT FOR WIZ004.
WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR WIZ002.
WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR WIZ003.
&&
$$
SHORT TERM...BERDES
AREA FORECAST DISCUSSION
NWS DULUTH MN
1127 AM CST TUE FEB 19 2013
.AVIATION...../18Z TAF ISSUANCE/
MAINLY VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD. THE ONLY
EXCEPTION WILL BE HIB WHERE SOME BLOWING SNOW WILL BRING SOME MVFR
VISIBILITIES FOR SEVERAL HOURS THIS AFTERNOON. THE GUSTY NORTH TO
NORTHWESTERLY WINDS WILL DIMINISH THIS EVENING. SKIES WILL BE MOSTLY
CLEAR THROUGHOUT THIS TAF FORECAST PERIOD. EXPECT LIGHT WINDS FROM
THE NORTHEAST BY THE END OF THIS TAF FORECAST PERIOD.
&&
PREV DISCUSSION... /ISSUED 321 AM CST TUE FEB 19 2013/
CURRENT...VERY DEEP MID LVL TROF CONTINUES TO AMPLIFY AS IT CRAWLS
ACROSS CWA EARLY THIS MORNING. SFC LOW OVER ERN WISC IS INTENSIFYING
AS IT MOVES TOWARDS ERN END OF LAKE SUPERIOR. LARGE SHIELD OF DEEP
LAYER MOISTURE ACCOMPANIED BY COLD ADVECTION IS KEEPING LIGHT SNOW
ACROSS REGION. A STANDING WAVE IS INDICATED... ACROSS DOUGLAS COUNTY
AND INTO SE CARLTON COUNTY NEAR HOLYOKE... IN THE ANIMATED 88D
REFL/VEL PRODUCTS AS NW FLOW INCREASES. SFC PRESS GRADIENT NEARLY
20MB ACROSS CWA WITH GUSTY WINDS ACROSS MOST OF MN ZONES. VERY
STRONG GUSTS ALONG NORTH SHORE FROM TWIN PORTS TO GRAND PORTAGE.
LOCAL KATABATIC ENHANCEMENT OCCURING FROM SILVER BAY NORTH TO BORDER
WHERE INLAND TERRAIN IS HIGHER. GUST OVER 50 MPH HAVE OCCURED IN
THIS CORRIDOR WITH HRRR 3KM OUTPUT SUGGESTING GUSTS MAY REACH 60 MPH
THROUGH EARLY MORNING. ARCTIC AIR HAS INFILTRATED THE NORTHWESTERN
CWA WITH SFC TEMPS BELOW ZERO. WINDCHILL ADVISORY MAY NOT VERIFY IN
MANY AREAS UNTIL BETWEEN 12Z-15Z WHEN MIN TEMPS ARE REACHED AND WIND
SPEEDS REMAIN RELATIVELY HIGH. .
TODAY/TONIGHT...SLOW MOVING MID LVL TROF WILL KEEP A CYCLONIC AND
RELATIVELY MOIST CIRCULATION OVER THE REGION. GUSTY WINDS ARE EXPECTD
TO CONTINUE AS SFC PRESS GRADIENT REMAINS QUITE LARGE ACROSS CWA.
BUFKIT MOMENTUM TRANSFER PROFILES SHOW GUSTS MAY LINGER WELL INTO
THE NIGHT AS WELL. NORTH SHORE STILL SUSCEPTIBLE TO KATABATIC
ENHANCEMENT OFF HIGHER PLATEAU WEST OF LAKE SUPERIOR...ESPECIALLY
COOK COUNTY THROUGH MID MORNING. DEEP LAYER DRYING WILL OCCUR FROM
WEST TO EAST TODAY OVER THE MN ZONES. MAIN STORY OVER WISC WILL BE
CONTINUATION OF LES ACROSS SNOW BELTS. LAKE INDUCED CAPE FORECAST
TO INCREASE TO 400/500 J/KG THIS AFTN. INVERSION HEIGHTS ARE
EXPECTED TO LIFT TO ABOUT 4K FT THIS AFTERNOON BEFORE LOWERING TO 2K
FT AFTER MDINIGHT TONIGHT. WILL KEEP CURRENT ADVISORY/WARNING FOR
SOUTH SHORE. WILL NEED ANOTHER WIND CHILL ADVISORY TONIGHT FOR MOST
OF CWA. WILL LET DAY SHIFT ISSUE THIS AFTER CURENT WINDC ADV EXPIRES.
MAX TEMPS TODAY WILL STRUGGLE ALL DAY TO GET ABOVE ZERO ACROSS THE
BORDERLAND AND IRON RANGE. SINGLE DIGITS ELSEWHERE. LOWERED PREVIOUS
TEMP FCST OVER INTERIOR WISC IN LINE WITH ECBC VALUES AND LOWER
TEMPS OF SREF PLUMES.
TOMORROW...PROGRESSIVE FLOW ALOFT WILL SEND A MID LVL RIDGE
OVERHEAD. STRONG SFC HIGH CENTERED OVER NRN ONTARIO WILL BUILD SOUTH
INTO CWA. ABUNDANT SUNSHINE TO START THE DAY ALTHOUGH HIGH CLOUDS
MAY INCREASE FROM THE SOUTHWEST IN THE AFTERNOON IN RESPONSE TO
UPPER LEVEL WARM ADVECTION FROM SRN ROCKIES STORM. TEMPS REMAIN
WELL BELOW CLIMO.
LONG TERM...WEDNESDAY NIGHT THROUGH TUESDAY.
FOCUS IN LONG TERM ON ACTIVE PATTERN FOR THE UPPER MIDWEST LATE IN
THE WEEK...AND EARLY NEXT WEEK.
UPPER LEVEL RIDGE WILL AMPLIFY OVER THE WRN GREAT LAKE REGION WED
NIGHT AS A VORT MAX ROUNDS THE BASE OF A LONG WAVE TROUGH IN THE SW
CONUS...DEEPENING INTO A CLOSED LOW AS IT LIFTS ACROSS THE CENTRAL
PLAINS THURSDAY. THE 00Z MODELS ARE SHOWING GOOD AGREEMENT THAT THE
H50 LOW PUSHES INTO THE SRN DAKOTAS/MINN THURSDAY
EVENING...CENTERING OVER MINNESOTA FRIDAY NIGHT. MEANWHILE...THE SFC
LOW REMAINS TO THE SW OF THE H50 LOW...TRACKING ACROSS IOWA THROUGH
THE DAY FRIDAY...REACHING UPPER MICHIGAN/CEN GREAT LAKES FRIDAY
NIGHT. HAVE MADE VERY LITTLE CHANGES TO POPS THURSDAY NIGHT/FRIDAY
AS THE LEADING EDGE OF THE MAIN SWATH OF SNOW IS EXPECTED TO IMPACT
THE SRN DLH ZONES THURSDAY EVENING...LIFTING OVER MUCH OR ALL OF THE
NORTHLAND THROUGH FRIDAY. TEMPERATURE PROFILES CONTINUE TO SUGGEST
PTYPE OF ALL SNOW FOR THE DLH CWA.
ALTHOUGH UNCERTAINTY REMAINS...MODELS HAVE SHOWN DECENT RUN TO RUN
AGREEMENT THAT A BAND OF HEAVY SNOW DEVELOPS ACROSS THE SRN HALF OF
MINNESOTA THURSDAY NIGHT INTO FRIDAY MORNING. LATEST GFS/ECM
CONTINUE TO SHOW VERY DRY AIR ASSOCIATED WITH A RIDGE AXIS EXTENDING
SOUTH FROM ONTARIO WILL BE DIFFICULT TO ERODE THURSDAY NIGHT...SO
HAVE TRENDED A WITH A SLOWER TIMING FOR INTRODUCING POPS. THE LATEST
NAM BUFR SOUNDING AT KBRD/KINL/KHYR DEPICT PWATS INITIALLY THURSDAY OF
ONLY 0.08". HOWEVER...THERE IS MOISTURE ASSOCIATED WITH THE LOW THAT
DOES ADVECT INTO THE REGION AS THE H50 LOW APPROACHES...ALLOWING
PWATS TO INCREASE TO AROUND 0.3" THROUGH FRIDAY NIGHT AT MOST
LOCATIONS.
HAVE INCREASED TO BROADBRUSH LIKELY POPS FOR LIGHT SNOW FRIDAY.
MODELS SUGGEST THE H50 LOW HANGS AROUND THE GREAT LAKES REGION
THROUGH THE WEEKEND...KEEPING CYCLONIC FLOW...CLOUDS AND LIGHT SNOW
CHANCES FOR THE NORTHLAND.
ALTHOUGH THE GFS IS SHOWING A TREND TOWARDS THE ECM SOLUTION FOR THE
SYSTEM THAT WILL IMPACT THE REGION EARLY NEXT WEEK...THERE REMAINS
LARGE DIFFERENCES IN TIMING AND STORM TRACK. THE ECM SOLUTION LIFTS
THE CLOSED LOW OVER THE DAKOTAS TUESDAY...WHILE THE LATEST GFS
SUGGESTS A FASTER AND MORE EASTERLY TRACK WITH THE H50 LOW PASSING
OVER MINN/WIS MONDAY NIGHT.
&&
.POINT TEMPS/POPS...
DLH 4 -12 13 4 / 20 10 0 0
INL 0 -24 8 -11 / 10 10 0 0
BRD 5 -14 13 -3 / 10 10 0 0
HYR 7 -14 15 -8 / 30 10 0 0
ASX 9 -8 15 -1 / 60 50 20 0
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...WIND CHILL ADVISORY UNTIL NOON CST TODAY FOR MNZ010>012-018>021-
025-026-033>037.
WI...WINTER STORM WARNING UNTIL MIDNIGHT CST TONIGHT FOR WIZ004.
WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR WIZ002.
WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR WIZ003.
&&
$$
AVIATION...KK
AREA FORECAST DISCUSSION
NWS DULUTH MN
610 AM CST TUE FEB 19 2013
.AVIATION.../12Z TAF ISSUANCE/
MAINLY VFR CIGS...WITH AREAS OF MVFR CEILINGS AROUND 2 KFT WITH 3-5
SM VSBY DUE TO BLSN...WILL PREVAIL THIS MORNING. SKIES WILL CLEAR
FROM THE WEST THROUGH THE AFTERNOON AS MUCH DRIER AIR FILTERS INTO
THE REGION. ALTHOUGH WIND SPEEDS WILL DIMINISH A BIT THIS
MORNING...THE STRONG NORTHWEST WINDS CONTINUE TODAY...RELAXING
DURING THE EVENING HOURS AS HIGH PRESSURE SETTLES INTO THE
NORTHLAND OVERNIGHT.
&&
.PREV DISCUSSION... /ISSUED 321 AM CST TUE FEB 19 2013/
CURRENT...VERY DEEP MID LVL TROF CONTINUES TO AMPLIFY AS IT CRAWLS
ACROSS CWA EARLY THIS MORNING. SFC LOW OVER ERN WISC IS INTENSIFYING
AS IT MOVES TOWARDS ERN END OF LAKE SUPERIOR. LARGE SHIELD OF DEEP
LAYER MOISTURE ACCOMPANIED BY COLD ADVECTION IS KEEPING LIGHT SNOW
ACROSS REGION. A STANDING WAVE IS INDICATED... ACROSS DOUGLAS COUNTY
AND INTO SE CARLTON COUNTY NEAR HOLYOKE... IN THE ANIMATED 88D
REFL/VEL PRODUCTS AS NW FLOW INCREASES. SFC PRESS GRADIENT NEARLY
20MB ACROSS CWA WITH GUSTY WINDS ACROSS MOST OF MN ZONES. VERY
STRONG GUSTS ALONG NORTH SHORE FROM TWIN PORTS TO GRAND PORTAGE.
LOCAL KATABATIC ENHANCEMENT OCCURING FROM SILVER BAY NORTH TO BORDER
WHERE INLAND TERRAIN IS HIGHER. GUST OVER 50 MPH HAVE OCCURED IN
THIS CORRIDOR WITH HRRR 3KM OUTPUT SUGGESTING GUSTS MAY REACH 60 MPH
THROUGH EARLY MORNING. ARCTIC AIR HAS INFILTRATED THE NORTHWESTERN
CWA WITH SFC TEMPS BELOW ZERO. WINDCHILL ADVISORY MAY NOT VERIFY IN
MANY AREAS UNTIL BETWEEN 12Z-15Z WHEN MIN TEMPS ARE REACHED AND WIND
SPEEDS REMAIN RELATIVELY HIGH. .
TODAY/TONIGHT...SLOW MOVING MID LVL TROF WILL KEEP A CYCLONIC AND
RELATIVELY MOIST CIRCULATION OVER THE REGION. GUSTY WINDS ARE EXPECTD
TO CONTINUE AS SFC PRESS GRADIENT REMAINS QUITE LARGE ACROSS CWA.
BUFKIT MOMENTUM TRANSFER PROFILES SHOW GUSTS MAY LINGER WELL INTO
THE NIGHT AS WELL. NORTH SHORE STILL SUSCEPTIBLE TO KATABATIC
ENHANCEMENT OFF HIGHER PLATEAU WEST OF LAKE SUPERIOR...ESPECIALLY
COOK COUNTY THROUGH MID MORNING. DEEP LAYER DRYING WILL OCCUR FROM
WEST TO EAST TODAY OVER THE MN ZONES. MAIN STORY OVER WISC WILL BE
CONTINUATION OF LES ACROSS SNOW BELTS. LAKE INDUCED CAPE FORECAST
TO INCREASE TO 400/500 J/KG THIS AFTN. INVERSION HEIGHTS ARE
EXPECTED TO LIFT TO ABOUT 4K FT THIS AFTERNOON BEFORE LOWERING TO 2K
FT AFTER MDINIGHT TONIGHT. WILL KEEP CURRENT ADVISORY/WARNING FOR
SOUTH SHORE. WILL NEED ANOTHER WIND CHILL ADVISORY TONIGHT FOR MOST
OF CWA. WILL LET DAY SHIFT ISSUE THIS AFTER CURENT WINDC ADV EXPIRES.
MAX TEMPS TODAY WILL STRUGGLE ALL DAY TO GET ABOVE ZERO ACROSS THE
BORDERLAND AND IRON RANGE. SINGLE DIGITS ELSEWHERE. LOWERED PREVIOUS
TEMP FCST OVER INTERIOR WISC IN LINE WITH ECBC VALUES AND LOWER
TEMPS OF SREF PLUMES.
TOMORROW...PROGRESSIVE FLOW ALOFT WILL SEND A MID LVL RIDGE
OVERHEAD. STRONG SFC HIGH CENTERED OVER NRN ONTARIO WILL BUILD SOUTH
INTO CWA. ABUNDANT SUNSHINE TO START THE DAY ALTHOUGH HIGH CLOUDS
MAY INCREASE FROM THE SOUTHWEST IN THE AFTERNOON IN RESPONSE TO
UPPER LEVEL WARM ADVECTION FROM SRN ROCKIES STORM. TEMPS REMAIN
WELL BELOW CLIMO.
LONG TERM...WEDNESDAY NIGHT THROUGH TUESDAY.
FOCUS IN LONG TERM ON ACTIVE PATTERN FOR THE UPPER MIDWEST LATE IN
THE WEEK...AND EARLY NEXT WEEK.
UPPER LEVEL RIDGE WILL AMPLIFY OVER THE WRN GREAT LAKE REGION WED
NIGHT AS A VORT MAX ROUNDS THE BASE OF A LONG WAVE TROUGH IN THE SW
CONUS...DEEPENING INTO A CLOSED LOW AS IT LIFTS ACROSS THE CENTRAL
PLAINS THURSDAY. THE 00Z MODELS ARE SHOWING GOOD AGREEMENT THAT THE
H50 LOW PUSHES INTO THE SRN DAKOTAS/MINN THURSDAY
EVENING...CENTERING OVER MINNESOTA FRIDAY NIGHT. MEANWHILE...THE SFC
LOW REMAINS TO THE SW OF THE H50 LOW...TRACKING ACROSS IOWA THROUGH
THE DAY FRIDAY...REACHING UPPER MICHIGAN/CEN GREAT LAKES FRIDAY
NIGHT. HAVE MADE VERY LITTLE CHANGES TO POPS THURSDAY NIGHT/FRIDAY
AS THE LEADING EDGE OF THE MAIN SWATH OF SNOW IS EXPECTED TO IMPACT
THE SRN DLH ZONES THURSDAY EVENING...LIFTING OVER MUCH OR ALL OF THE
NORTHLAND THROUGH FRIDAY. TEMPERATURE PROFILES CONTINUE TO SUGGEST
PTYPE OF ALL SNOW FOR THE DLH CWA.
ALTHOUGH UNCERTAINTY REMAINS...MODELS HAVE SHOWN DECENT RUN TO RUN
AGREEMENT THAT A BAND OF HEAVY SNOW DEVELOPS ACROSS THE SRN HALF OF
MINNESOTA THURSDAY NIGHT INTO FRIDAY MORNING. LATEST GFS/ECM
CONTINUE TO SHOW VERY DRY AIR ASSOCIATED WITH A RIDGE AXIS EXTENDING
SOUTH FROM ONTARIO WILL BE DIFFICULT TO ERODE THURSDAY NIGHT...SO
HAVE TRENDED A WITH A SLOWER TIMING FOR INTRODUCING POPS. THE LATEST
NAM BUFR SOUNDING AT KBRD/KINL/KHYR DEPICT PWATS INITIALLY THURSDAY OF
ONLY 0.08". HOWEVER...THERE IS MOISTURE ASSOCIATED WITH THE LOW THAT
DOES ADVECT INTO THE REGION AS THE H50 LOW APPROACHES...ALLOWING
PWATS TO INCREASE TO AROUND 0.3" THROUGH FRIDAY NIGHT AT MOST
LOCATIONS.
HAVE INCREASED TO BROADBRUSH LIKELY POPS FOR LIGHT SNOW FRIDAY.
MODELS SUGGEST THE H50 LOW HANGS AROUND THE GREAT LAKES REGION
THROUGH THE WEEKEND...KEEPING CYCLONIC FLOW...CLOUDS AND LIGHT SNOW
CHANCES FOR THE NORTHLAND.
ALTHOUGH THE GFS IS SHOWING A TREND TOWARDS THE ECM SOLUTION FOR THE
SYSTEM THAT WILL IMPACT THE REGION EARLY NEXT WEEK...THERE REMAINS
LARGE DIFFERENCES IN TIMING AND STORM TRACK. THE ECM SOLUTION LIFTS
THE CLOSED LOW OVER THE DAKOTAS TUESDAY...WHILE THE LATEST GFS
SUGGESTS A FASTER AND MORE EASTERLY TRACK WITH THE H50 LOW PASSING
OVER MINN/WIS MONDAY NIGHT.
&&
.POINT TEMPS/POPS...
DLH 4 -12 13 4 / 20 10 0 0
INL 1 -24 8 -11 / 10 10 0 0
BRD 4 -14 13 -3 / 10 10 0 0
HYR 8 -14 15 -8 / 30 10 0 0
ASX 10 -8 15 -1 / 60 40 20 0
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...WIND CHILL ADVISORY UNTIL NOON CST TODAY FOR MNZ010>012-018>021-
025-026-033>037.
WI...WINTER STORM WARNING UNTIL MIDNIGHT CST TONIGHT FOR WIZ004.
WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR WIZ002.
WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR WIZ003.
&&
$$
AVIATION...GRANING
AREA FORECAST DISCUSSION
NWS DULUTH MN
321 AM CST TUE FEB 19 2013
.CURRENT...VERY DEEP MID LVL TROF CONTINUES TO AMPLIFY AS IT CRAWLS
ACROSS CWA EARLY THIS MORNING. SFC LOW OVER ERN WISC IS INTENSIFYING
AS IT MOVES TOWARDS ERN END OF LAKE SUPERIOR. LARGE SHIELD OF DEEP
LAYER MOISTURE ACCOMPANIED BY COLD ADVECTION IS KEEPING LIGHT SNOW
ACROSS REGION. A STANDING WAVE IS INDICATED... ACROSS DOUGLAS COUNTY
AND INTO SE CARLTON COUNTY NEAR HOLYOKE... IN THE ANIMATED 88D
REFL/VEL PRODUCTS AS NW FLOW INCREASES. SFC PRESS GRADIENT NEARLY
20MB ACROSS CWA WITH GUSTY WINDS ACROSS MOST OF MN ZONES. VERY
STRONG GUSTS ALONG NORTH SHORE FROM TWIN PORTS TO GRAND PORTAGE.
LOCAL KATABATIC ENHANCEMENT OCCURING FROM SILVER BAY NORTH TO BORDER
WHERE INLAND TERRAIN IS HIGHER. GUST OVER 50 MPH HAVE OCCURED IN
THIS CORRIDOR WITH HRRR 3KM OUTPUT SUGGESTING GUSTS MAY REACH 60 MPH
THROUGH EARLY MORNING. ARCTIC AIR HAS INFILTRATED THE NORTHWESTERN
CWA WITH SFC TEMPS BELOW ZERO. WINDCHILL ADVISORY MAY NOT VERIFY IN
MANY AREAS UNTIL BETWEEN 12Z-15Z WHEN MIN TEMPS ARE REACHED AND WIND
SPEEDS REMAIN RELATIVELY HIGH. .
TODAY/TONIGHT...SLOW MOVING MID LVL TROF WILL KEEP A CYCLONIC AND
RELATIVELY MOIST CIRCULATION OVER THE REGION. GUSTY WINDS ARE EXPECTD
TO CONTINUE AS SFC PRESS GRADIENT REMAINS QUITE LARGE ACROSS CWA.
BUFKIT MOMENTUM TRANSFER PROFILES SHOW GUSTS MAY LINGER WELL INTO
THE NIGHT AS WELL. NORTH SHORE STILL SUSCEPTIBLE TO KATABATIC
ENHANCEMENT OFF HIGHER PLATEAU WEST OF LAKE SUPERIOR...ESPECIALLY
COOK COUNTY THROUGH MID MORNING. DEEP LAYER DRYING WILL OCCUR FROM
WEST TO EAST TODAY OVER THE MN ZONES. MAIN STORY OVER WISC WILL BE
CONTINUATION OF LES ACROSS SNOW BELTS. LAKE INDUCED CAPE FORECAST
TO INCREASE TO 400/500 J/KG THIS AFTN. INVERSION HEIGHTS ARE
EXPECTED TO LIFT TO ABOUT 4K FT THIS AFTERNOON BEFORE LOWERING TO 2K
FT AFTER MDINIGHT TONIGHT. WILL KEEP CURRENT ADVISORY/WARNING FOR
SOUTH SHORE. WILL NEED ANOTHER WIND CHILL ADVISORY TONIGHT FOR MOST
OF CWA. WILL LET DAY SHIFT ISSUE THIS AFTER CURENT WINDC ADV EXPIRES.
MAX TEMPS TODAY WILL STRUGGLE ALL DAY TO GET ABOVE ZERO ACROSS THE
BORDERLAND AND IRON RANGE. SINGLE DIGITS ELSEWHERE. LOWERED PREVIOUS
TEMP FCST OVER INTERIOR WISC IN LINE WITH ECBC VALUES AND LOWER
TEMPS OF SREF PLUMES.
TOMORROW...PROGRESSIVE FLOW ALOFT WILL SEND A MID LVL RIDGE
OVERHEAD. STRONG SFC HIGH CENTERED OVER NRN ONTARIO WILL BUILD SOUTH
INTO CWA. ABUNDANT SUNSHINE TO START THE DAY ALTHOUGH HIGH CLOUDS
MAY INCREASE FROM THE SOUTHWEST IN THE AFTERNOON IN RESPONSE TO
UPPER LEVEL WARM ADVECTION FROM SRN ROCKIES STORM. TEMPS REMAIN
WELL BELOW CLIMO.
LONG TERM...WEDNESDAY NIGHT THROUGH TUESDAY.
FOCUS IN LONG TERM ON ACTIVE PATTERN FOR THE UPPER MIDWEST LATE IN
THE WEEK...AND EARLY NEXT WEEK.
UPPER LEVEL RIDGE WILL AMPLIFY OVER THE WRN GREAT LAKE REGION WED
NIGHT AS A VORT MAX ROUNDS THE BASE OF A LONG WAVE TROUGH IN THE SW
CONUS...DEEPENING INTO A CLOSED LOW AS IT LIFTS ACROSS THE CENTRAL
PLAINS THURSDAY. THE 00Z MODELS ARE SHOWING GOOD AGREEMENT THAT THE
H50 LOW PUSHES INTO THE SRN DAKOTAS/MINN THURSDAY
EVENING...CENTERING OVER MINNESOTA FRIDAY NIGHT. MEANWHILE...THE SFC
LOW REMAINS TO THE SW OF THE H50 LOW...TRACKING ACROSS IOWA THROUGH
THE DAY FRIDAY...REACHING UPPER MICHIGAN/CEN GREAT LAKES FRIDAY
NIGHT. HAVE MADE VERY LITTLE CHANGES TO POPS THURSDAY NIGHT/FRIDAY
AS THE LEADING EDGE OF THE MAIN SWATH OF SNOW IS EXPECTED TO IMPACT
THE SRN DLH ZONES THURSDAY EVENING...LIFTING OVER MUCH OR ALL OF THE
NORTHLAND THROUGH FRIDAY. TEMPERATURE PROFILES CONTINUE TO SUGGEST
PTYPE OF ALL SNOW FOR THE DLH CWA.
ALTHOUGH UNCERTAINTY REMAINS...MODELS HAVE SHOWN DECENT RUN TO RUN
AGREEMENT THAT A BAND OF HEAVY SNOW DEVELOPS ACROSS THE SRN HALF OF
MINNESOTA THURSDAY NIGHT INTO FRIDAY MORNING. LATEST GFS/ECM
CONTINUE TO SHOW VERY DRY AIR ASSOCIATED WITH A RIDGE AXIS EXTENDING
SOUTH FROM ONTARIO WILL BE DIFFICULT TO ERODE THURSDAY NIGHT...SO
HAVE TRENDED A WITH A SLOWER TIMING FOR INTRODUCING POPS. THE LATEST
NAM BUFR SOUNDING AT KBRD/KINL/KHYR DEPICT PWATS INITIALLY THURSDAY OF
ONLY 0.08". HOWEVER...THERE IS MOISTURE ASSOCIATED WITH THE LOW THAT
DOES ADVECT INTO THE REGION AS THE H50 LOW APPROACHES...ALLOWING
PWATS TO INCREASE TO AROUND 0.3" THROUGH FRIDAY NIGHT AT MOST
LOCATIONS.
HAVE INCREASED TO BROADBRUSH LIKELY POPS FOR LIGHT SNOW FRIDAY.
MODELS SUGGEST THE H50 LOW HANGS AROUND THE GREAT LAKES REGION
THROUGH THE WEEKEND...KEEPING CYCLONIC FLOW...CLOUDS AND LIGHT SNOW
CHANCES FOR THE NORTHLAND.
ALTHOUGH THE GFS IS SHOWING A TREND TOWARDS THE ECM SOLUTION FOR THE
SYSTEM THAT WILL IMPACT THE REGION EARLY NEXT WEEK...THERE REMAINS
LARGE DIFFERENCES IN TIMING AND STORM TRACK. THE ECM SOLUTION LIFTS
THE CLOSED LOW OVER THE DAKOTAS TUESDAY...WHILE THE LATEST GFS
SUGGESTS A FASTER AND MORE EASTERLY TRACK WITH THE H50 LOW PASSING
OVER MINN/WIS MONDAY NIGHT.
.AVIATION...06Z TAFS
MOSTLY MVFR CEILINGS COVERED THE NORTHLAND LATE THIS EVENING...BUT
THERE WERE SOME VFR CEILINGS THAT WERE OCCURRING AS WELL.
FOLLOWING CLOSER TO THE RAP/S 925-950MB CONDENSATION PRESSURE
DEFICITS...WHICH ARE DOING AN OK JOB...KEEPS MOSTLY MVFR CEILINGS
TONIGHT INTO TUESDAY MORNING...BEFORE WE SEE SOME IMPROVEMENT.
THERE MAY CONTINUE TO BE POCKETS OF VFR CONDITIONS OVERNIGHT
THOUGH.
STRONG NORTHWEST WINDS WILL CONTINUE THROUGH MUCH OF THE
PERIOD...STRONGEST AROUND LAKE SUPERIOR.
.POINT TEMPS/POPS...
DLH 4 -12 13 4 / 20 10 0 0
INL 1 -24 8 -11 / 10 10 0 0
BRD 4 -14 13 -3 / 10 10 0 0
HYR 8 -14 15 -8 / 30 10 0 0
ASX 10 -8 15 -1 / 60 40 20 0
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...WIND CHILL ADVISORY UNTIL NOON CST TODAY FOR MNZ010>012-018>021-
025-026-033>037.
WI...WINTER STORM WARNING UNTIL MIDNIGHT CST TONIGHT FOR WIZ004.
WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR WIZ002.
WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR WIZ003.
&&
$$
SHORT TERM...CANNON
LONG TERM....GRANING
AREA FORECAST DISCUSSION
NWS HASTINGS NE
939 PM CST WED FEB 20 2013
.UPDATE...
ISSUED AT 928 PM CST WED FEB 20 2013
NOT A WHOLE LOT OF CHANGES TO THE FORECAST FOR TONIGHT ASIDE FROM
INCREASING SNOWFALL AMOUNTS IN OUR SOUTHWEST ZONES WHERE A 9 INCH
AMOUNT HAS BEEN RECEIVED IN PLAINVILLE KS IN ROOKS COUNTY. FARTHER
EAST...THE DRIER AIR HAS BEEN SLOW TO OVERCOME AND HAVE LOWERED
SNOWFALL AMOUNTS SLIGHTLY FOR OUR EAST/NORTHEAST ZONES. SNOW HAS
BEGUN TO INCREASE IN COVERAGE ACROSS OUR SOUTHWEST CWA AND THE
SNOW WILL SPREAD NORTH OVERNIGHT. OUR EASTERN AREAS COULD STILL
PICK UP AN INCH OR TWO PRIOR TO DAYBREAK...ALTHOUGH THE HIGHER
AMOUNTS WILL STILL BE REALIZED ACROSS SOUTHERN/WESTERN AREAS. THE
00Z RUN OF THE NAM REMAINS CONSISTENT WITH THE UPPER LOW LIFTING
NORTHEAST FM THE TX PANHANDLE THURSDAY MORNING INTO EAST CENTRAL
KS BY 00Z FRIDAY. DEFORMATION SNOWFALL WILL DEVELOP ACROSS KS
EARLY THURSDAY AND SPREAD NORTHWARD AS SYSTEMS LIFTS NORTHEAST
DURING THE DAY. WE ARE STILL LOOKING AT WIDESPREAD HEAVY SNOWFALL
DEVELOPING IN KS THURSDAY MORNING AND SPREADING INTO NEBRASKA BY
THURSDAY AFTN AND CONTINUING INTO THE EVENING. 00Z NAM STORM TOTAL
SNOWFALL REMAINS CONSISTENT WITH PREVIOUS RUNS AND OTHER MODELS
WITH POTENTIAL OF 10 INCHES OR MORE OF SNOW...WITH WELL OVER A
FOOT POSSIBLE ACROSS NC KS INTO SW/SC NEB.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 239 PM CST WED FEB 20 2013
TONIGHT THROUGH EARLY FRIDAY MORNING...FOCUS CONTINUES
TO BE ON THE APPROACHING UPPER LEVEL DISTURBANCE CURRENTLY VISIBLE
IN WATER VAPOR IMAGERY CIRCULATING ACROSS CENTRAL ARIZONA. MOISTURE
AHEAD OF THIS DISTURBANCE HAS BEEN SURGING NORTHWARD FOR MUCH OF THE
DAY TODAY...WITH LIGHT SNOW SLOWLY SPREADING NORTHWARD INTO PORTIONS
OF SOUTH CENTRAL NEBRASKA THE PAST FEW HOURS. EXPECT THIS LIGHT SNOW
TO CONTINUE THROUGH THE EVENING HOURS...AND INTENSIFY SOME
OVERNIGHT. WITH THE OVERALL SLOWER AND MORE SOUTHEASTWARD TRACK OF
THIS SYSTEM...NOW EXPECT THE HEAVIEST SNOWFALL TO DEVELOP IN BANDS
ACROSS NORTH CENTRAL KANSAS DURING THE EARLY MORNING HOURS
THURSDAY...WORKING ITS WAY INTO SOUTH CENTRAL NEBRASKA BY MID
MORNING. THAT SAID...STILL EXPECT SOME SNOWFALL ACCUMULATIONS THIS
AFTERNOON AND EVENING...ESPECIALLY ACROSS THE SOUTHWESTERN SECTIONS
OF THE FORECAST AREA...WITH LIGHT SNOWFALL POSSIBLY NOT WORKING INTO
THE EASTERN FRINGES OF THE LOCAL AREA UNTIL ABOUT MIDNIGHT.
LATEST RAP CONTINUES TO BE THE MAIN OUTLIER HOLDING OFF WIDESPREAD
SNOW UNTIL AROUND DAYBREAK THURSDAY FOR MUCH OF THE EASTERN HALF OF
THE FORECAST AREA...DUE TO ITS DEPICTION OF A MORE SIGNIFICANT DRY
LAYER NEAR THE GROUND IN THE LOW LEVEL EASTERLY FLOW. HOWEVER...WITH
THE NAM/SREF/GFS/EC/WRF ALL DEVELOPING MORE WIDESPREAD PRECIPITATION
BEFORE THEN...MOSTLY DISCOUNTED RAP ANALYSIS...AND KEPT ONSET OF
PRECIPITATION SIMILAR TO THIS MORNINGS FORECAST. OTHERWISE...WHILE
THE OVERALL TIMING OF THE MAIN SYSTEM ACROSS THE DESERT SOUTHWEST
HAS SLOWED DOWN A BIT IN THE 12Z MODELS...IT STILL LOOKS TO BE A
MAJOR WINTER STORM EVENT...AND HAVE ADJUSTED FOR THE SLOWER ANALYSIS
BY EXTENDING THE WINTER STORM WARNING FOR THE NORTH/NORTHEASTERN
HALF OF THE AREA BY 6 HOURS. AND WHILE OVERALL LIQUID EQUIVALENTS
HAVE COME DOWN TO AROUND AN INCH FOR THE TRI CITIES AREA WITH THIS
SYSTEM...RANGING FROM AROUND 0.75 IN THE EC TO AROUND 1.2 IN THE
NAM...INCREASED SNOWFALL RATIOS TO BE SLIGHTLY HIGHER THAN
PREVIOUSLY THOUGHT IN THIS COLD AIRMASS...SO ONLY VERY MINOR TWEAKS
ARE EVIDENT IN THE OVERALL SNOWFALL ACCUMULATIONS.
IN ADDITION TO SNOWFALL...EXPECT BREEZY SOUTHEASTERLY WINDS TO
CONTINUE THROUGH THE EVENING AND OVERNIGHT HOURS...AS THE PRESSURE
GRADIENT BEGINS TO TIGHTEN AHEAD OF THE APPROACHING SURFACE LOW.
WINDS ARE THEN EXPECTED TO EVENTUALLY RELAX AND SHIFT MORE NORTHERLY
ON THE BACKSIDE OF THE SURFACE LOW AS IT CROSSES INTO MISSOURI AND
IOWA BY TOMORROW EVENING. HOWEVER...WITH LOTS OF FAIRLY DRY SNOW AND
BREEZY WINDS...VISIBILITIES ARE EXPECTED TO BE REDUCED IN AREAS OF
BLOWING SNOW THROUGH THE DURATION OF THIS EVENT...NOT IMPROVING TIL
AFTER 00Z...AND KEPT AREAS OF BLOWING SNOW IN THE FORECAST AS A
CONSEQUENCE.
TEMPERATURES THROUGH THIS EVENT ARE EXPECTED TO REMAIN ON THE COLD
SIDE OF CLIMATOLOGY FOR MID FEBRUARY...WITH AFTERNOON HIGHS ON
THURSDAY LIKELY NOT RISING MUCH ABOVE THE MORNING LOWS AS THE CLOUD
COVER AND SNOW WILL PUT A CAP ON HEATING ACROSS THE LOCAL AREA.
TEMPERATURES ARE THEN EXPECTED TO PLUMMET FRIDAY MORNING ON THE
BACKSIDE OF THIS SYSTEM...AS SOME CLEARING ALONG WITH RELAXING WINDS
AND FRESH SNOW COVER SHOULD ALLOW FOR GOOD RADIATIONAL COOLING BY
EARLY FRIDAY MORNING.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 239 PM CST WED FEB 20 2013
PATTERN: THIS IS A STORMY PATTERN AND EXCITING IF YOU/RE A WINTER WX
FAN. WE ARE LIKELY TO SEE WINTERS FURY CONTINUE FULL BORE THRU THE
END OF THE MONTH. THIS MEANS AT LEAST ONE MORE SNOW/WIND STORM AND
COLDER THAN NORMAL DAYTIME TEMPS...WITH SEVERAL DAYS OF MUCH BELOW
NORMAL /ANYTHING 33F OR BELOW/. THE -PNA/-NAO IS DICTATING THE
LONG-WAVE PATTERN WHICH FEATURES A STORMY WRN USA TROF AND
INCREASING DOWNSTREAM BLOCKING OVER ERN N AMERICA.
FOR THOSE NOT EXCITED ABOUT WINTER WX...THE PNA WILL REACH ITS
LOWEST POINT THIS WEEK AND THEN TURN POSITIVE THE 1ST WEEK OF MAR.
THE ANOMALOUS E PAC RIDGE /+2 STANDARD DEVIATION HGTS/ WILL TAKE A
BIG HIT NEXT MON-TUE FROM A DEEPENING GULF OF AK STORM. THIS WILL
INITIATE THE RETROGRESSION AND REPOSITION THE LONG-WAVE TROF FURTHER
W...INDUCING A RIDGE OVER THE WRN USA NEXT WED.
HAZARDS: THERE IS POTENTIAL FOR ANOTHER WINTER STORM SUN NGT-MON
WITH APPRECIABLE AMOUNTS OF SNOW POSSIBLE.
UPCOMING PCPN OPPORTUNITIES: 2/25.
FRI THE STORM CONTINUES TO EXIT. ANOTHER PIECE OF ENERGY MOVES
THRU SAT...ON THE BACKSIDE OF THE TROF. THE NEXT POTENT TROF DIVES
INTO THE INTERMOUNTAIN W IN THE MEANTIME...AND DEEPENS SUN-MON AS
WAVELENGTH DECREASES. ANOTHER VORT MAX FOLLOWS INTO THE DESERT SW
TUE AND THIS ODDS FAVOR THIS STORM BEING SUPPRESSED FAR TO OUR S.
THE DAILY DETAILS...
CONFIDENCE IS BELOW AVERAGE ON OUR DAYTIME HIGHS THRU THE PERIOD
SINCE MODELS STRUGGLE WITH SUBSTANTIAL SNOW-PACK ON THE GROUND. WE
MAY NOT BE COLD ENOUGH.
FRI: CLEAN-UP AND RECOVERY BUT VERY COLD WITH PLENTY OF CLOUDS. ANY
BREAKS THAT DEVELOP WILL FILL BACK IN UNDER THERMAL TROF. CANT
COMPLETELY RULE OUT A STRAY AFTN FLURRY. WINDS NOT BAD.
SAT: QUIET INTERLUDE. CONFIDENCE IS AVERAGE. WOULDNT RULE OUT SOME
FLURRIES...BUT LOW-LEVEL MSTR APPEARS LIMITED.
SAT NGT: MAINTAINED CONTINUITY WITH PREVIOUS FCST FOR A SLGT CHANCE
OF FRZG DRZL...BUT WITH LOW CONFIDENCE. INCREASING LOW-LEVEL MSTR
OVER A COLD SNOW PACK COULD RESULT IN STRATUS. DID REMOVE FLURRIES
FROM THE FCST. LOW-LEVEL THERMAL PROFILES MAY NOT BE COLD ENOUGH
FOR SNOW GRAINS.
SUN: BACKED DOWN POPS TO SLGT CHANCE.
SUN NGT-MON: THIS STORM COULD BE TROUBLE. COORDINATED WITH HPC AT
1530Z. BELIEVE THIS STORM TAKES A VERY SIMILAR TRACK TO THE CURRENT
STORM. THE DIFF IS THIS STORM IS WE/RE GETTING A SIGNAL THAT IT
LINGERS OR STALLS OVER ERN KS DURING THE DAYLIGHT HRS MON...BEFORE
SLOWLY HEADING TOWARD THE GREAT LAKES MON NGT-TUE.
ACCUMULATING/PLOWABLE SNOW REQUIRING WATCHES/WARNINGS/ADVISORIES
APPEARS LIKELY BASED ON TRENDS IN THE LAST 72 HRS. BUT THIS DOES
NOT NECESSARILY MEAN FOR OUR ENTIRE FCST AREA. POPS HAVE BEEN
INCREASED TO 60-70%. THINK WE NEED TO PREPARE FOR THE OPTION OF A
SLOW-MOVING...POSSIBLY LONG-LIVED STORM. THE BLOCKING HIGH
DOWNSTREAM URGES CAUTION.
THIS STORM HAS POTENTIAL TO BE VERY WINDY.
MODELS: 1456Z PMDEPD AND HPC GUIDANCE REVIEWED AND WE ARE IN
AGREEMENT ON A SLOWER SOLUTION PER THE EC/GEM ENSEMBLES. MOST GFS
ENSEMBLE MEMBERS LOOK TOO FAST/PROGRESSIVE AS EARLY AS 12Z/SUN. EVEN
THE HIGHER RES OPERATIONAL GFS RUNS ARE TOWARD THE SLOWER PACK.
TUE: CYCLONIC FLOW GRADUALLY RELEASES BUT STILL EXPECT PLENTY OF
CLOUDS THRU MIDDAY UNDER THERMAL TROF. BEST IMPROVEMENT S AND W OF
TRI-CITIES.
WED: QUIET AND DRY.
NAO/PNA TELECONNECTIONS: THESE REFER TO THE NORTH ATLANTIC
OSCILLATION AND PACIFIC-NORTH AMERICAN OSCILLATION. THESE
OSCILLATIONS DEAL WITH RIDGES/TROFS AND PATTERNS IN THE JET
STREAM. THE VARIOUS CONFIGURATIONS DICTATE WHAT OUR SENSIBLE
WEATHER WILL BE...ABOVE OR BELOW NORMAL TEMPS...AND DRIER OR
WETTER THAN NORMAL.
-PNA: THIS IS A TROF OVER THE WRN USA. COLDER AND STORMIER FOR THE
CNTRL PLAINS.
+PNA: THIS IS A RIDGE OVER THE WRN USA. THIS IS A QUIET AND MILD
PATTERN HERE.
THE NAO IS MOSTLY A PLAYER IN OUR STORM TRACKS HERE ON THE PLAINS.
+NAO: NO BLOCKING IN THE ATMOSPHERE NEAR GREENLAND. AT TIMES...
THIS ALLOWS COLORADO LOWS TO TRACK MORE ACROSS NEB.
-NAO: BLOCKING NEAR GREENLAND. THIS TENDS TO FORCE COLORADO LOWS
TO OUR S...ACROSS KS.
THIS WEBSITE HAS ADDITIONAL INFO...SOME OF WHICH IS TECHNICAL.
CHECK OUT THE MAPS THAT INDICATE INDICATE THE POSITIVE PHASES.
WARM COLORS INDICATE WARMER TEMPS AND DECREASED STORMINESS. COLD
COLORS INDICATE COLDER TEMPS AND INCREASED STORMINESS. FOR THE
NEGATIVE PHASES...JUST REVERSE THE COLORS. THESE TELECONNECTIONS
HAVE THE GREATEST IMPACTS IN THE COOLER MONTHS OF THE YEAR.
WWW.CPC.NCEP.NOAA.GOV/DATA/TELEDOC/TELEINTRO.SHTML (ALL LOWER CASE)
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 502 PM CST WED FEB 20 2013
CONDITIONS WILL CONTINUE TO DETERIORATE THROUGH THE TAF PERIOD.
LIGHT SNOW HAS ALREADY DEVELOPED AT THE TERMINAL THIS
EVENING...AND SNOW WILL BE INTERMITTENT FOR THE FIRST PART OF THE
NIGHT AND WILL INCREASE IN INTENSITY TOWARD THURSDAY MORNING AS A
WINTER STORM SYSTEM EMERGES ONTO THE PLAINS. THE SNOW WILL BE HEAVY AT
TIMES ON THURSDAY WITH CONDITIONS AT LIFR THRU MUCH OF THE DAY.
THE SNOW WILL TAPER OFF THURSDAY NIGHT.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...WINTER STORM WARNING UNTIL MIDNIGHT CST THURSDAY NIGHT FOR
NEZ039>041-046>049-060>064-072>077-085>087.
WINTER STORM WARNING UNTIL 6 PM CST THURSDAY FOR NEZ082>084.
KS...WINTER STORM WARNING UNTIL 6 PM CST THURSDAY FOR KSZ005>007-
017>019.
&&
$$
UPDATE...FAY
SHORT TERM...ROSSI
LONG TERM...HALBLAUB
AVIATION...FAY
AREA FORECAST DISCUSSION
NWS HASTINGS NE
512 PM CST WED FEB 20 2013
.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 239 PM CST WED FEB 20 2013
TONIGHT THROUGH EARLY FRIDAY MORNING...FOCUS CONTINUES
TO BE ON THE APPROACHING UPPER LEVEL DISTURBANCE CURRENTLY VISIBLE
IN WATER VAPOR IMAGERY CIRCULATING ACROSS CENTRAL ARIZONA. MOISTURE
AHEAD OF THIS DISTURBANCE HAS BEEN SURGING NORTHWARD FOR MUCH OF THE
DAY TODAY...WITH LIGHT SNOW SLOWLY SPREADING NORTHWARD INTO PORTIONS
OF SOUTH CENTRAL NEBRASKA THE PAST FEW HOURS. EXPECT THIS LIGHT SNOW
TO CONTINUE THROUGH THE EVENING HOURS...AND INTENSIFY SOME
OVERNIGHT. WITH THE OVERALL SLOWER AND MORE SOUTHEASTWARD TRACK OF
THIS SYSTEM...NOW EXPECT THE HEAVIEST SNOWFALL TO DEVELOP IN BANDS
ACROSS NORTH CENTRAL KANSAS DURING THE EARLY MORNING HOURS
THURSDAY...WORKING ITS WAY INTO SOUTH CENTRAL NEBRASKA BY MID
MORNING. THAT SAID...STILL EXPECT SOME SNOWFALL ACCUMULATIONS THIS
AFTERNOON AND EVENING...ESPECIALLY ACROSS THE SOUTHWESTERN SECTIONS
OF THE FORECAST AREA...WITH LIGHT SNOWFALL POSSIBLY NOT WORKING INTO
THE EASTERN FRINGES OF THE LOCAL AREA UNTIL ABOUT MIDNIGHT.
LATEST RAP CONTINUES TO BE THE MAIN OUTLIER HOLDING OFF WIDESPREAD
SNOW UNTIL AROUND DAYBREAK THURSDAY FOR MUCH OF THE EASTERN HALF OF
THE FORECAST AREA...DUE TO ITS DEPICTION OF A MORE SIGNIFICANT DRY
LAYER NEAR THE GROUND IN THE LOW LEVEL EASTERLY FLOW. HOWEVER...WITH
THE NAM/SREF/GFS/EC/WRF ALL DEVELOPING MORE WIDESPREAD PRECIPITATION
BEFORE THEN...MOSTLY DISCOUNTED RAP ANALYSIS...AND KEPT ONSET OF
PRECIPITATION SIMILAR TO THIS MORNINGS FORECAST. OTHERWISE...WHILE
THE OVERALL TIMING OF THE MAIN SYSTEM ACROSS THE DESERT SOUTHWEST
HAS SLOWED DOWN A BIT IN THE 12Z MODELS...IT STILL LOOKS TO BE A
MAJOR WINTER STORM EVENT...AND HAVE ADJUSTED FOR THE SLOWER ANALYSIS
BY EXTENDING THE WINTER STORM WARNING FOR THE NORTH/NORTHEASTERN
HALF OF THE AREA BY 6 HOURS. AND WHILE OVERALL LIQUID EQUIVALENTS
HAVE COME DOWN TO AROUND AN INCH FOR THE TRI CITIES AREA WITH THIS
SYSTEM...RANGING FROM AROUND 0.75 IN THE EC TO AROUND 1.2 IN THE
NAM...INCREASED SNOWFALL RATIOS TO BE SLIGHTLY HIGHER THAN
PREVIOUSLY THOUGHT IN THIS COLD AIRMASS...SO ONLY VERY MINOR TWEAKS
ARE EVIDENT IN THE OVERALL SNOWFALL ACCUMULATIONS.
IN ADDITION TO SNOWFALL...EXPECT BREEZY SOUTHEASTERLY WINDS TO
CONTINUE THROUGH THE EVENING AND OVERNIGHT HOURS...AS THE PRESSURE
GRADIENT BEGINS TO TIGHTEN AHEAD OF THE APPROACHING SURFACE LOW.
WINDS ARE THEN EXPECTED TO EVENTUALLY RELAX AND SHIFT MORE NORTHERLY
ON THE BACKSIDE OF THE SURFACE LOW AS IT CROSSES INTO MISSOURI AND
IOWA BY TOMORROW EVENING. HOWEVER...WITH LOTS OF FAIRLY DRY SNOW AND
BREEZY WINDS...VISIBILITIES ARE EXPECTED TO BE REDUCED IN AREAS OF
BLOWING SNOW THROUGH THE DURATION OF THIS EVENT...NOT IMPROVING TIL
AFTER 00Z...AND KEPT AREAS OF BLOWING SNOW IN THE FORECAST AS A
CONSEQUENCE.
TEMPERATURES THROUGH THIS EVENT ARE EXPECTED TO REMAIN ON THE COLD
SIDE OF CLIMATOLOGY FOR MID FEBRUARY...WITH AFTERNOON HIGHS ON
THURSDAY LIKELY NOT RISING MUCH ABOVE THE MORNING LOWS AS THE CLOUD
COVER AND SNOW WILL PUT A CAP ON HEATING ACROSS THE LOCAL AREA.
TEMPERATURES ARE THEN EXPECTED TO PLUMMET FRIDAY MORNING ON THE
BACKSIDE OF THIS SYSTEM...AS SOME CLEARING ALONG WITH RELAXING WINDS
AND FRESH SNOW COVER SHOULD ALLOW FOR GOOD RADIATIONAL COOLING BY
EARLY FRIDAY MORNING.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 239 PM CST WED FEB 20 2013
PATTERN: THIS IS A STORMY PATTERN AND EXCITING IF YOU/RE A WINTER WX
FAN. WE ARE LIKELY TO SEE WINTERS FURY CONTINUE FULL BORE THRU THE
END OF THE MONTH. THIS MEANS AT LEAST ONE MORE SNOW/WIND STORM AND
COLDER THAN NORMAL DAYTIME TEMPS...WITH SEVERAL DAYS OF MUCH BELOW
NORMAL /ANYTHING 33F OR BELOW/. THE -PNA/-NAO IS DICTATING THE
LONG-WAVE PATTERN WHICH FEATURES A STORMY WRN USA TROF AND
INCREASING DOWNSTREAM BLOCKING OVER ERN N AMERICA.
FOR THOSE NOT EXCITED ABOUT WINTER WX...THE PNA WILL REACH ITS
LOWEST POINT THIS WEEK AND THEN TURN POSITIVE THE 1ST WEEK OF MAR.
THE ANOMALOUS E PAC RIDGE /+2 STANDARD DEVIATION HGTS/ WILL TAKE A
BIG HIT NEXT MON-TUE FROM A DEEPENING GULF OF AK STORM. THIS WILL
INITIATE THE RETROGRESSION AND REPOSITION THE LONG-WAVE TROF FURTHER
W...INDUCING A RIDGE OVER THE WRN USA NEXT WED.
HAZARDS: THERE IS POTENTIAL FOR ANOTHER WINTER STORM SUN NGT-MON
WITH APPRECIABLE AMOUNTS OF SNOW POSSIBLE.
UPCOMING PCPN OPPORTUNITIES: 2/25.
FRI THE STORM CONTINUES TO EXIT. ANOTHER PIECE OF ENERGY MOVES
THRU SAT...ON THE BACKSIDE OF THE TROF. THE NEXT POTENT TROF DIVES
INTO THE INTERMOUNTAIN W IN THE MEANTIME...AND DEEPENS SUN-MON AS
WAVELENGTH DECREASES. ANOTHER VORT MAX FOLLOWS INTO THE DESERT SW
TUE AND THIS ODDS FAVOR THIS STORM BEING SUPPRESSED FAR TO OUR S.
THE DAILY DETAILS...
CONFIDENCE IS BELOW AVERAGE ON OUR DAYTIME HIGHS THRU THE PERIOD
SINCE MODELS STRUGGLE WITH SUBSTANTIAL SNOW-PACK ON THE GROUND. WE
MAY NOT BE COLD ENOUGH.
FRI: CLEAN-UP AND RECOVERY BUT VERY COLD WITH PLENTY OF CLOUDS. ANY
BREAKS THAT DEVELOP WILL FILL BACK IN UNDER THERMAL TROF. CANT
COMPLETELY RULE OUT A STRAY AFTN FLURRY. WINDS NOT BAD.
SAT: QUIET INTERLUDE. CONFIDENCE IS AVERAGE. WOULDNT RULE OUT SOME
FLURRIES...BUT LOW-LEVEL MSTR APPEARS LIMITED.
SAT NGT: MAINTAINED CONTINUITY WITH PREVIOUS FCST FOR A SLGT CHANCE
OF FRZG DRZL...BUT WITH LOW CONFIDENCE. INCREASING LOW-LEVEL MSTR
OVER A COLD SNOW PACK COULD RESULT IN STRATUS. DID REMOVE FLURRIES
FROM THE FCST. LOW-LEVEL THERMAL PROFILES MAY NOT BE COLD ENOUGH
FOR SNOW GRAINS.
SUN: BACKED DOWN POPS TO SLGT CHANCE.
SUN NGT-MON: THIS STORM COULD BE TROUBLE. COORDINATED WITH HPC AT
1530Z. BELIEVE THIS STORM TAKES A VERY SIMILAR TRACK TO THE CURRENT
STORM. THE DIFF IS THIS STORM IS WE/RE GETTING A SIGNAL THAT IT
LINGERS OR STALLS OVER ERN KS DURING THE DAYLIGHT HRS MON...BEFORE
SLOWLY HEADING TOWARD THE GREAT LAKES MON NGT-TUE.
ACCUMULATING/PLOWABLE SNOW REQUIRING WATCHES/WARNINGS/ADVISORIES
APPEARS LIKELY BASED ON TRENDS IN THE LAST 72 HRS. BUT THIS DOES
NOT NECESSARILY MEAN FOR OUR ENTIRE FCST AREA. POPS HAVE BEEN
INCREASED TO 60-70%. THINK WE NEED TO PREPARE FOR THE OPTION OF A
SLOW-MOVING...POSSIBLY LONG-LIVED STORM. THE BLOCKING HIGH
DOWNSTREAM URGES CAUTION.
THIS STORM HAS POTENTIAL TO BE VERY WINDY.
MODELS: 1456Z PMDEPD AND HPC GUIDANCE REVIEWED AND WE ARE IN
AGREEMENT ON A SLOWER SOLUTION PER THE EC/GEM ENSEMBLES. MOST GFS
ENSEMBLE MEMBERS LOOK TOO FAST/PROGRESSIVE AS EARLY AS 12Z/SUN. EVEN
THE HIGHER RES OPERATIONAL GFS RUNS ARE TOWARD THE SLOWER PACK.
TUE: CYCLONIC FLOW GRADUALLY RELEASES BUT STILL EXPECT PLENTY OF
CLOUDS THRU MIDDAY UNDER THERMAL TROF. BEST IMPROVEMENT S AND W OF
TRI-CITIES.
WED: QUIET AND DRY.
NAO/PNA TELECONNECTIONS: THESE REFER TO THE NORTH ATLANTIC
OSCILLATION AND PACIFIC-NORTH AMERICAN OSCILLATION. THESE
OSCILLATIONS DEAL WITH RIDGES/TROFS AND PATTERNS IN THE JET
STREAM. THE VARIOUS CONFIGURATIONS DICTATE WHAT OUR SENSIBLE
WEATHER WILL BE...ABOVE OR BELOW NORMAL TEMPS...AND DRIER OR
WETTER THAN NORMAL.
-PNA: THIS IS A TROF OVER THE WRN USA. COLDER AND STORMIER FOR THE
CNTRL PLAINS.
+PNA: THIS IS A RIDGE OVER THE WRN USA. THIS IS A QUIET AND MILD
PATTERN HERE.
THE NAO IS MOSTLY A PLAYER IN OUR STORM TRACKS HERE ON THE PLAINS.
+NAO: NO BLOCKING IN THE ATMOSPHERE NEAR GREENLAND. AT TIMES...
THIS ALLOWS COLORADO LOWS TO TRACK MORE ACROSS NEB.
-NAO: BLOCKING NEAR GREENLAND. THIS TENDS TO FORCE COLORADO LOWS
TO OUR S...ACROSS KS.
THIS WEBSITE HAS ADDITIONAL INFO...SOME OF WHICH IS TECHNICAL.
CHECK OUT THE MAPS THAT INDICATE INDICATE THE POSITIVE PHASES.
WARM COLORS INDICATE WARMER TEMPS AND DECREASED STORMINESS. COLD
COLORS INDICATE COLDER TEMPS AND INCREASED STORMINESS. FOR THE
NEGATIVE PHASES...JUST REVERSE THE COLORS. THESE TELECONNECTIONS
HAVE THE GREATEST IMPACTS IN THE COOLER MONTHS OF THE YEAR.
WWW.CPC.NCEP.NOAA.GOV/DATA/TELEDOC/TELEINTRO.SHTML (ALL LOWER CASE)
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 502 PM CST WED FEB 20 2013
CONDITIONS WILL CONTINUE TO DETERIORATE THROUGH THE TAF PERIOD.
LIGHT SNOW HAS ALREADY DEVELOPED AT THE TERMINAL THIS
EVENING...AND SNOW WILL BE INTERMITTENT FOR THE FIRST PART OF THE
NIGHT AND WILL INCREASE IN INTENSITY TOWARD THURSDAY MORNING AS A
WINTER STORM SYSTEM EMERGES ONTO THE PLAINS. THE SNOW WILL BE HEAVY AT
TIMES ON THURSDAY WITH CONDITIONS AT LIFR THRU MUCH OF THE DAY.
THE SNOW WILL TAPER OFF THURSDAY NIGHT.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...WINTER STORM WARNING UNTIL MIDNIGHT CST THURSDAY NIGHT FOR
NEZ039>041-046>049-061>064-074>077-085>087.
WINTER STORM WARNING UNTIL MIDNIGHT CST THURSDAY NIGHT FOR
NEZ060-072-073.
WINTER STORM WARNING UNTIL 6 PM CST THURSDAY FOR NEZ082>084.
KS...WINTER STORM WARNING UNTIL 6 PM CST THURSDAY FOR KSZ005>007-
017>019.
&&
$$
SHORT TERM...ROSSI
LONG TERM...HALBLAUB
AVIATION...FAY
AREA FORECAST DISCUSSION
NWS ALBUQUERQUE NM
321 PM MST TUE FEB 19 2013
.DISCUSSION...
LAST TWO HOURS OF SURFACE OBS AND THE CIRA DERIVED PWAT VALUES SHOW
SOME OF THE STRONGEST MOISTURE ADVECTION THIS FORECASTER HAS SEEN IN
A LONG TIME. DEWPOINT VALUES ACROSS SOUTHERN NM ROSE FROM THE SINGLE
DIGITS INTO THE 30S AND LOW 40S BTWN 15Z AND 21Z. SOUTH TO SOUTHWEST
FLOW USHERING IN THIS MOISTURE WILL SPREAD ACROSS NM TONIGHT...THUS
OVERNIGHT LOWS WILL BE SIGNIFICANTLY WARMER THAN THE PAST SEVERAL.
12Z/18Z BUFKIT PROFILES AND LATEST RUC SOLUTION SHOWING BIG TIME TOP
DOWN MOISTENING THIS EVENING LEADING TO A LOW CLOUD LAYER WITH LIGHT
RAIN SHOWERS AND DRIZZLE ACROSS MUCH OF THE EAST. HAVE RAISED POPS
IN THIS AREA CONSIDERABLY. THIS DEEP SURGE OF LOW LEVEL MOISTURE IS
IN RESPONSE TO A DEEPER 534DM H5 LOW OVER CENTRAL CALIFORNIA DIGGING
CONTINUOUSLY FARTHER SOUTH EACH RUN...THUS BACKING LOW LEVEL WIND
FIELDS MORE EFFICIENTLY.
WITH THIS TRACK AND DEEPER MOISTURE HAVE ESSENTIALLY INCREASED POPS
ALL AREAS. ACCORDINGLY THE 700-500MB LAYER WIND FIELDS HAVE SHIFTED
MORE INTO SOUTHERN NM INCREASING CONFIDENCE THAT HIGH WIND SPEEDS
WILL NOT IMPACT OUR REGION. THE SUITE OF HI RES MODEL SOLUTIONS AND
THE FOCUS FOR DYNAMICS ON THE LATEST MODEL SOLUTIONS HAVE INCREASED
CONFIDENCE ENOUGH TO UPGRADE THE WINTER STORM WATCH TO A WARNING FOR
ALL MT ZONES AND CONVERT TO ADVISORY FOR A FEW OTHERS. ALSO ADDED
THE SANGRE DE CRISTO MTS TO THE WARNING. THE MAIN IMPACT PERIOD FOR
MOIST UPSLOPE COLD ADVECTIVE WESTERLY FLOW WILL BE WEDNESDAY NIGHT
INTO THURSDAY...SO THAT SEGMENT WILL BE VALID FOR SLIGHTLY LONGER.
TEMPS WILL TAKE A NOSE DIVE WEDNESDAY AFTERNOON FROM WEST TO EAST...
WITH A FEW AREAS OUT WEST SEEING HIGHS IN THE MORNING.
WE SHOULD NOT FORGOT THAT MOIST INSTABILITY ALONG THE PACIFIC COLD
FRONTAL BNDRY WILL BE SUFFICIENT TO GENERATE A LINE OF STORMS OVER
THE FAR EASTERN PLAINS LATE WEDNESDAY AFT. BLOWING DUST WILL BE AN
ISSUE BEHIND THIS FRONT FOR THE PECOS AND LOWER RIO GRANDE VALLEY
AREAS. DID REMOVE MOST OF THE BLOWING SNOW WORDING FOR THE NORTH
AND WEST AS AGAIN THE WINDS APPEAR STRONGEST MUCH FARTHER SOUTH.
A SECONDARY WAVE WILL SLIDE OVER THE AREA THURSDAY/FRIDAY WITH WEAK
FORCING AND SLIGHTLY MORE COLD ADVECTION. THIS FEATURE WILL FOCUS
THE ACTION MAINLY ON THE HIGHER TERRAIN WHERE MOISTURE FROM THE
FIRST SYSTEM IS SQUEEZED OUT. A BRIEF BREAK WILL SLIDE OVER LATE
FRIDAY/SATURDAY...BEFORE ANOTHER WIND BAG ARRIVES SUNDAY. MODELS
JUST KEEP IT COMING NEXT WEEK WITH ANOTHER POTENTIAL STORM TUESDAY.
GUYER
&&
.FIRE WEATHER...
A STRING OF WEATHER SYSTEMS WILL CROSS THE FORECAST AREA WEDNESDAY
THROUGH MONDAY. THERE WILL BE SOME FIRE WEATHER CONCERNS EAST OF THE
CENTRAL MOUNTAINS SATURDAY...MONDAY AND ESPECIALLY SUNDAY.
THE FIRST STORM IN THE SERIES WILL PROBABLY PRODUCE THE MOST
PRECIPITATION AND THE STRONGEST WINDS. MODELS KEEP NUDGING THIS
SYSTEM FURTHER SOUTH WITH EACH RUN...AND THE LOW PRESSURE CENTER IS
NOW EXPECTED TO PASS EASTWARD FROM QUEMADO TO TUCUMCARI WEDNESDAY
THROUGH WEDNESDAY NIGHT. THE POTENTIAL EXISTS FOR SEVERAL INCHES OF
SNOW BY THURSDAY MORNING ACROSS THE NORTHERN AND WESTERN
MOUNTAINS...WITH A FEW INCHES TO POSSIBLY A HALF FOOT AT LOWER
ELEVATIONS OF THE WEST CENTRAL AND NORTHWEST PLATEAU AND LIGHTER
AMOUNTS IN THE UPPER RIO GRANDE VALLEY. FARTHER SOUTH AND EAST THE
MAIN WEATHER CONCERN WILL BE WIND. THE POLAR JET STREAM WILL CROSS
SOUTHERN NM ON WEDNESDAY...THEN A STRONG SURFACE LOW IN THE LEE OF
THE SOUTHERN CO ROCKIES WILL KEEP THE PRESSURE GRADIENT TIGHT AND
WINDS STRONG ACROSS EASTERN NM WEDNESDAY NIGHT THROUGH THURSDAY.
GUSTS UP TO 50 MPH ARE EXPECTED FROM AROUND SOCORRO TO AROUND GRAN
QUIVIRA DURING EARLY AFTERNOON WEDNESDAY...THEN THESE STRONG WINDS
SHOULD SPREAD NORTHEASTWARD ALONG THE EAST SLOPES OF THE CENTRAL AND
SOUTHERN SANGRE DE CRISTO MOUNTAINS DURING THE LATE AFTERNOON AND
NIGHT. A COLD FRONT WILL ALSO CROSS FROM THE WEST WEDNESDAY AND
WEDNESDAY NIGHT...WITH MECHANICAL MIXING HELPING TO KEEP WINDS GOING
THROUGH THE NIGHT IN THE EAST.
IN THE WAKE OF THE COLD FRONT...HIGH TEMPERATURES THURSDAY WILL FALL
A FEW TO 8 DEGREES BELOW WEDNESDAYS READINGS. THE SURFACE PRESSURE
GRADIENT WILL REMAIN TIGHT IN THE EAST. WIND GUSTS TO 50 MPH ARE
EXPECTED TO CONTINUE FROM CLINES CORNERS TO SUMNER LAKE UNTIL SUNSET
THURSDAY EVENING. JUST AS THE FIRST UPPER LOW EXITS THURSDAY
MORNING...A TRAILING UPPER TROUGH WILL DIVE SOUTHEASTWARD THROUGH
THE FORECAST AREA THURSDAY AFTERNOON THROUGH FRIDAY. THIS WILL CAUSE
SNOW SHOWERS TO LINGER...BUT THIS SYSTEM WILL BE SIGNIFICANTLY
DRIER. THERE MAY BE A FEW INCHES OF ADDITIONAL SNOW ACCUMULATION IN
THE NORTHERN AND POSSIBLY THE WESTERN MOUNTAINS. HIGH TEMPERATURES
THURSDAY AND FRIDAY WILL VARY FROM 5 TO 20 DEGREES BELOW NORMAL.
THE AREA WILL BE BETWEEN STORM SYSTEMS SATURDAY. WEAK RIDGING WILL
PRODUCE TEMPERATURES 8 TO 15 DEGREES WARMER THAN FRIDAYS READINGS.
WEST WINDS WILL BECOME BREEZY TO WINDY AGAIN IN THE LEE OF THE
CENTRAL MOUNTAINS DUE TO A STRONG SURFACE LEE TROUGH AND
STRENGTHENING WINDS ALOFT AHEAD OF THE NEXT WEATHER SYSTEM. POCKETS
OF MINIMUM HUMIDITIES IN THE LOWER TEENS SHOULD RESULT IN AN HOUR OR
TWO OF CRITICAL FIRE WEATHER CONDITIONS ON THE EAST CENTRAL PLAINS.
A MORE CRITICAL FIRE WEATHER PATTERN MAY DEVELOP FOR NM SUNDAY AS AN
UPPER TROUGH STRENGTHENS INTO A CLOSED UPPER LOW WHILE PASSING
EASTWARD OVER CO AND/OR NORTHERN NM. THIS WILL STEER A STRONG POLAR
JET STREAK OVER THE SOUTHERN ROCKIES WHILE DRIVING A COLD FRONT
SOUTHWARD THROUGH NM. NW WIND GUSTS MAY PEAK AROUND 50 MPH FROM THE
SANDIA AND MANZANO MOUNTAINS EASTWARD ONTO THE EAST CENTRAL PLAINS.
MUCH OF THIS AREA MAY EXPERIENCE SEVERAL HOURS OF CRITICAL FIRE
WEATHER CONDITIONS. MODELS DISAGREE ON HOW FAR SOUTH THE UPPER LOW
WILL CROSS. IF IT DROPS AS FAR SOUTH AS NORTHERN NM...THEN THE
NORTHERN AND WESTERN MOUNTAINS COULD RECEIVE A FEW TO SEVERAL
ADDITIONAL INCHES OF SNOW BY MONDAY MORNING. MONDAY SHOULD SEE HIGH
TEMPERATURES ROUGHLY 6 TO 16 DEGREES BELOW NORMAL. AFTER AN EXTENDED
PERIOD OF GOOD TO EXCELLENT VENTILATION...MAX VENT RATES MONDAY MAY
NOT GET OUT OF THE POOR CATEGORY IN MANY LOWER ELEVATION
LOCATIONS.
44
&&
.AVIATION...
18Z TAF CYCLE
SOUTHERLY FLOW WILL STRENGTHEN OVER NM TODAY AND PERSIST THROUGH
TONIGHT AS AN UPPER LEVEL LOW PRESSURE SYSTEM APPROACHES FROM THE
WEST. LOW LEVEL MOISTURE ADVECTION SHOULD CAUSE LOW CLOUDS TO
OVERSPREAD MUCH OF THE E CENTRAL AND SE PLAINS DURING THE
EVENING...BEFORE PUSHING INTO NE AREAS AFTER MIDNIGHT AND
POSSIBLY OVER KSAF WITH A SE CANYON WIND TOWARD SUNRISE. THERE IS ONLY
ABOUT 50 PERCENT CONFIDENCE THAT LOW CLOUDS WILL REACH KSAF. THE MVFR
AND IFR LOW CLOUDS MAY BE ACCOMPANIED BY LOCALLY DENSE FOG E OF
THE CENTRAL MTN CHAIN TONIGHT...BUT PERSISTENT WINDS SHOULD KEEP
THE FOG AT BAY IN MANY LOCATIONS. ISOLD -SHRA MAY ALSO DEVELOP
ACROSS THE E CENTRAL AND SE PLAINS OVERNIGHT...WHILE ISOLD TO SCT
-SHSN FAVOR LOCATIONS ALONG AND W OF THE CONTDVD. PCPN WILL BECOME
MORE WDSPR OVER W AND N AREAS WEDNESDAY AS A COLD FRONT CROSSES
THE NM/AZ BORDER. AHEAD OF THE FRONT...WINDS WILL SHIFT OUT OF THE
SW AND STRENGTHEN WITH GUSTS 30 TO 45 KT AS THE POLAR JET MOVES
OHD. A FEW TS WILL ALSO BE POSSIBLE ACROSS THE E CENTRAL AND NE
PLAINS WEDNESDAY AFTN.
44
&&
.PRELIMINARY POINT TEMPS/POPS...
FARMINGTON...................... 29 42 26 42 / 10 80 60 20
DULCE........................... 19 38 17 38 / 20 80 70 30
CUBA............................ 25 40 18 39 / 5 60 80 30
GALLUP.......................... 27 40 20 43 / 10 70 60 20
EL MORRO........................ 22 37 15 32 / 10 80 80 30
GRANTS.......................... 23 43 17 42 / 5 40 60 10
QUEMADO......................... 26 38 17 36 / 20 70 60 20
GLENWOOD........................ 26 39 15 40 / 5 60 60 5
CHAMA........................... 22 34 15 32 / 30 80 80 40
LOS ALAMOS...................... 30 41 22 38 / 5 30 70 20
PECOS........................... 29 41 20 35 / 20 20 60 20
CERRO/QUESTA.................... 17 38 16 35 / 5 30 70 20
RED RIVER....................... 20 31 13 30 / 20 60 80 40
ANGEL FIRE...................... 18 36 12 29 / 10 50 70 30
TAOS............................ 25 41 21 38 / 5 30 70 20
MORA............................ 26 40 19 37 / 20 30 60 20
ESPANOLA........................ 30 47 24 45 / 5 10 60 10
SANTA FE........................ 31 42 21 38 / 10 20 70 20
SANTA FE AIRPORT................ 32 46 22 42 / 5 20 60 10
ALBUQUERQUE FOOTHILLS........... 34 46 24 44 / 5 10 50 5
ALBUQUERQUE HEIGHTS............. 36 49 26 46 / 5 10 40 5
ALBUQUERQUE VALLEY.............. 36 51 25 49 / 5 10 40 5
ALBUQUERQUE WEST MESA........... 35 50 25 50 / 5 10 40 5
LOS LUNAS....................... 34 51 24 49 / 5 10 30 5
RIO RANCHO...................... 35 49 25 47 / 5 10 40 5
SOCORRO......................... 33 53 26 54 / 5 5 30 5
SANDIA PARK/CEDAR CREST......... 32 43 22 43 / 20 30 60 20
TIJERAS......................... 33 45 24 46 / 5 20 60 10
MORIARTY/ESTANCIA............... 32 46 21 41 / 20 10 60 10
CLINES CORNERS.................. 31 42 21 39 / 30 20 50 10
GRAN QUIVIRA.................... 33 44 21 42 / 20 10 40 10
CARRIZOZO....................... 33 49 23 45 / 10 10 30 5
RUIDOSO......................... 32 43 21 38 / 30 20 50 10
CAPULIN......................... 28 42 22 31 / 30 40 60 30
RATON........................... 25 46 23 41 / 20 30 50 20
SPRINGER........................ 27 47 24 46 / 20 20 40 20
LAS VEGAS....................... 29 44 20 42 / 30 20 40 10
CLAYTON......................... 32 45 27 39 / 40 30 60 30
ROY............................. 34 47 26 45 / 40 20 40 10
CONCHAS......................... 41 56 32 55 / 40 10 30 5
SANTA ROSA...................... 39 56 29 51 / 30 5 20 5
TUCUMCARI....................... 42 56 32 56 / 50 10 30 5
CLOVIS.......................... 39 55 29 53 / 40 10 20 5
PORTALES........................ 40 57 31 55 / 40 10 20 5
FORT SUMNER..................... 42 62 31 54 / 30 5 20 5
ROSWELL......................... 42 68 33 60 / 40 5 10 5
PICACHO......................... 35 58 27 51 / 30 5 20 5
ELK............................. 34 52 24 46 / 40 10 30 5
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY FROM 11 AM WEDNESDAY TO MIDNIGHT MST WEDNESDAY NIGHT
FOR THE FOLLOWING ZONES...NMZ520-524>526-539-540.
WINTER STORM WARNING FROM 6 AM WEDNESDAY TO 6 AM MST THURSDAY FOR
THE FOLLOWING ZONES...NMZ502>506-508>511.
WINTER STORM WARNING FROM 6 AM WEDNESDAY TO NOON MST THURSDAY FOR
THE FOLLOWING ZONES...NMZ512>514.
WINTER WEATHER ADVISORY FROM 6 AM WEDNESDAY TO 6 AM MST THURSDAY
FOR THE FOLLOWING ZONES...NMZ501-507-516.
&&
$$
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
955 PM EST WED FEB 20 2013
.SYNOPSIS...
A NORTHWEST FLOW OF COLD AIR ACROSS THE FINGER LAKES WILL KEEP
LAKE EFFECT SNOW SHOWERS OVER CENTRAL NEW YORK INTO THURSDAY...
ALTHOUGH THE SNOW SHOWERS WILL WEAKEN AS HIGH PRESSURE BUILDS IN
AND SLOWLY CLEARS OUR SKIES. IT WILL REMAIN MOSTLY DRY ON FRIDAY
BEFORE A COMPLEX STORM SYSTEM OVER THE GREAT LAKES AND MID
ATLANTIC COAST PUSHES MIXED PRECIPITATION INTO THE AREA.
&&
.NEAR TERM /THROUGH THURSDAY/...
950 PM UPDATE...
LAKE BAND IS FINALLY SHOWING SIGNS OF A SOUTHWARD PUSH. WILL
CONTINUE GRID FORECAST UPDATED A FEW YEARS AGO, WITH THE NEXT
TARGET BECOMING NORTHERN ONONDAGA COUNTY. BAND IS STILL FORECAST
TO WEAKEN QUICKLY DUE TO COLLAPSING INVERSION HEIGHTS.
750 PM UPDATE...
STILL NO MOVEMENT SOUTHWARD TO LAKE BAND, WHICH IS SHOWING A
LITTLE MORE ORGANIZATION DEVELOPING. LATEST RAP DROPS THE BAND
INTO ONONDAGA COUNTY AROUND 3Z AND WEAKENS IT THEREAFTER.
AT THIS POINT I HAVE A HEALTHY DOSE OF SKEPITICISM REGARDING THE
NEWEST MESOSCALE MODEL RUNS, AS OTHERS HAVE HANDLED THE SITUATION
POORLY. SFC WIND AND PRESSURE OBSERVATIONS ARE NOT SUGGESTING A
BIG MOVE COMING. COULD ARGUE FOR EXTENDING THE ADVISORY FOR N.
ONEIDA, BUT DO NOT ANTICIPATE MORE THAN AN ADDITIONAL INCH OR TWO
TONIGHT.
610 PM UPDATE...
LAKE EFFECT BAND IS DEFYING THE SHORT TERM MODELS, AND IS
RESISTING THE FORECAST TO DRIFT SOUTHWARD INTO ONONDAGA COUNTY.
THE BAND HAS ALSO WEAKENED CONSIDERABLY IN THE LAST HOUR, THOUGH
WITH NIGHTTIME UPON US AND DAYTIME THEMALS LONG GONE, IT WOULD NOT
BE SURPRISING TO SEE REORGANIZATION.
THE GRIDS HAVE BEEN ADJUSTED TO DELAY THE LES ONSET INTO ONONDAGA-
MADISON BY 1-2 HOURS. WILL CONTINUE TO MONITOR BAND STRENGTH ONCE
IT MAKES ITS MOVE FOR POTENTIAL ADVISORY. SHOULD CURRENT RADAR
TRENDS HOLD, THERE WILL BE NO NEED FOR A FLAG.
3 PM UPDATE...
MESO SCALE MODELS AND FCST SNDGS SHOW THE BAND SLOWLY DRFTG
SOUTH OVRNGT AND WEAKENING. CRNT KTYX 88D IMAGES SHOW A SOMEWHAT
MORE DISORGANIZED BAND NOW IN THE ADVISORY AREA AND INDEED VERY
SLOWLY MVG SOUTH. SOMEWHAT CNRND THAT ANOTHER SPOKE ROTATING ARND
THE UPR LOW COULD DELAY THE SWRD MVMT AND QUICKLY GIVE PART OF THE
FCST AREA NEAR ADVISORY SNOW THIS EVE. AIR STILL PLENTY COLD WITH
-14C AIR CORE OVER THE LAKE. HWVR...SINKING MOTION SHOWN IN THE
SNDGS CONTS TO LWR THE INV PTNLY WEAKENING THE BAND REGARDLESS OF
THE FLOW. ATTM WILL CONT WITH THE ADVISORY FOR NRN ONEIDA AND PUT
ACCUMS JUST BLO CRITERIA IN NRN ONONDAGA AND SRN ONEIDA.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
LE WILL LINGER INTO THU WITH CONTD COLD AIR AND NW FLOW. HIPRES
SFC AND ALOFT FNLY BLDS IN FOR FRI AS THE CLSD LOW DRIFTS EAST IN
RESPONSE TO THE DVLPG COMPLEX OVER THE CNTR OF THE COUNTRY. FRI
LOOKS SUNNY WITH SLGTLY ABV NRML TEMPS.
COMPLEX SCENARIO AND TRICKY FCST UNFOLDING FOR THE END OF THE SHRT
TERM. YET ANOTHER CLSD LOW OVER THE GREAT LAKES TRIES TO PHASE
WITH A SRN STREAM SHRT WV TRAVELING UP THE EAST CST. MODELS
TYPICALLY HAVE TROUBLE WITH DVLPG LOWS AND THIS IS COMPLCATED BY
THE DFCLTY IN PLACING THE MEANDERING CLSD UPR LOW OVER THE WRN
LAKES. CONSENSUS NOW IS TO DVLP THE SRN STREAM IMPULSE ENOUGH TO
PUSH MORE SUBSTANTIAL PCPN BACK INTO THE SERN ZONES...NAMELY THE
PA AND THE WRN CATS. OTR COMPLICATING FACTOR IS PCPN TYPE WITH A
COMPLETE LACK OF COLD AIR...EVEN OVER NRN NEW ENG. SO...IT LOOKS
VERY MUCH LIKE AN EARLY SPRING LIKE SCENARIO WITH MIXED PCPN...OR
LRG VLY/HILL DFRNCS. CNRT WWE FCST GIVE THE SERN ZONES A 4 TO 6
INCH ACCUM...2 TO 4 ELSEWHERE. WILL CONT A MENTION IN THE HWO FOR
NOW AND XPCT CONTG CHGS TO THE FCST AS THE WEEKEND APRCHS.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
1 PM UPDATE...
BLOCKY PATTERN WITH TWO CLOSED LOWS MOVING THROUGH IN THE LONG
TERM. BOTH APPEAR TO BE MINOR FOR THE CWA. THE FIRST WILL BE
FRIDAY TO SUNDAY. THE UPPER LEVEL LOW WILL BE IN THE GREAT LAKES
SAT NGT WITH A NOREASTER FORMING. MOST MODELS HAVE A NEAR MISS.
THE TROF GOES NEGATIVE TILT WHICH SLOWS THE SNOW FROM EXITING
UNTIL SUNDAY. A WEAK LAKE RESPONSE ON THE BACK SIDE OF THE STORM
SUNDAY NIGHT TO MONDAY. LATE MONDAY A LARGE AREA OF HIGH PRESSURE
MOVES IN AT THE SFC AND ALOFT.
TUESDAY TO WEDNESDAY DO IT ALL OVER AGAIN WITH ANOTHER STACKED
LOW. THE EURO HANDLES THIS STORM SLOWER WITH THE LOW IN ILLINOIS
TUES MORN MOVG TO SSM WED. WARM AIR COMES NORTH WITH THE OCCLUDED
FRONT SO PRECIP WILL BE MIXED. THE GFS BRINGS THE STACKED LOW ENE
OVER NY/PA SO A BETTER CHC OF SNOW.
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
A COLD NORTHWEST FLOW WILL PERSIST THROUGH THIS TAF PERIOD
BRINGING A CONTINUATION OF SNOW SHOWERS AND FLURRIES. AN ORGANIZED
AND WELL DEFINED LAKE EFFECT SNOW BAND OFF LAKE ONTARIO WILL
GRADUALLY DROP SOUTH THIS EVENING WHILE WEAKENING.
AT KRME...GENERALLY IFR SNOW SHOWERS WILL CONTINUE THROUGH 04Z
THEN DROP SOUTH OF THE TERMINAL WITH MVFR SNOW SHOWERS EXPECTED
TIL 09Z THEN VFR WITH CIGS AROUND 3,500 FT.
AT KSYR...IFR WITH OCCASIONAL BELOW ALT MIN CONDITIONS THROUGH
04Z. AFTER 08Z CONDITIONS SHOULD IMPROVE TO MVFR SNOW SHOWERS AND
FLURRIES.
AT KITH/KBGM...GENERALLY MVFR CONDITIONS DUE TO CIGS WITH
OCCASIONAL MVFR VSBY RESTRICTIONS IN SNOW SHOWERS LATE TONIGHT
THROUGH THURSDAY.
AT KELM/KAVP...GENERALLY VFR WITH CIGS AROUND 4K FT AND SNOW FLURRIES.
WEST WINDS 10-15 KNOTS WITH GUSTS AROUND 25 KNOTS DURING THE
DAYLIGHT HOURS ON THURSDAY.
.OUTLOOK...
THU NGT/FRI MORN...VFR.
FRI AFTN TO SAT NGT...MVFR/IFR IN MIXED PCPN.
SUN...VFR...MAYBE MVFR IN NY WITH LAKE ENHANCED SNOW SHOWERS.
MON...VFR.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...DGM
NEAR TERM...DGM/DJP
SHORT TERM...DGM
LONG TERM...TAC
AVIATION...RRM
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
752 PM EST WED FEB 20 2013
.SYNOPSIS...
A NORTHWEST FLOW OF COLD AIR ACROSS THE FINGER LAKES WILL KEEP
LAKE EFFECT SNOW SHOWERS OVER CENTRAL NEW YORK INTO THURSDAY...
ALTHOUGH THE SNOW SHOWERS WILL WEAKEN AS HIGH PRESSURE BUILDS IN
AND SLOWLY CLEARS OUR SKIES. IT WILL REMAIN MOSTLY DRY ON FRIDAY
BEFORE A COMPLEX STORM SYSTEM OVER THE GREAT LAKES AND MID
ATLANTIC COAST PUSHES MIXED PRECIPITATION INTO THE AREA.
&&
.NEAR TERM /THROUGH THURSDAY/...
750 PM UPDATE...
STILL NO MOVEMENT SOUTHWARD TO LAKE BAND, WHICH IS SHOWING A
LITTLE MORE ORGANIZATION DEVELOPING. LATEST RAP DROPS THE BAND
INTO ONONDAGA COUNTY AROUND 3Z AND WEAKENS IT THEREAFTER.
AT THIS POINT I HAVE A HEALTHY DOSE OF SKEPITICISM REGARDING THE
NEWEST MESOSCALE MODEL RUNS, AS OTHERS HAVE HANDLED THE SITUATION
POORLY. SFC WIND AND PRESSURE OBSERVATIONS ARE NOT SUGGESTING A
BIG MOVE COMING. COULD ARGUE FOR EXTENDING THE ADVISORY FOR N.
ONEIDA, BUT DO NOT ANTICIPATE MORE THAN AN ADDITIONAL INCH OR TWO
TONIGHT.
610 PM UPDATE...
LAKE EFFECT BAND IS DEFYING THE SHORT TERM MODELS, AND IS
RESISTING THE FORECAST TO DRIFT SOUTHWARD INTO ONONDAGA COUNTY.
THE BAND HAS ALSO WEAKENED CONSIDERABLY IN THE LAST HOUR, THOUGH
WITH NIGHTTIME UPON US AND DAYTIME THEMALS LONG GONE, IT WOULD NOT
BE SURPRISING TO SEE REORGANIZATION.
THE GRIDS HAVE BEEN ADJUSTED TO DELAY THE LES ONSET INTO ONONDAGA-
MADISON BY 1-2 HOURS. WILL CONTINUE TO MONITOR BAND STRENGTH ONCE
IT MAKES ITS MOVE FOR POTENTIAL ADVISORY. SHOULD CURRENT RADAR
TRENDS HOLD, THERE WILL BE NO NEED FOR A FLAG.
3 PM UPDATE...
MESO SCALE MODELS AND FCST SNDGS SHOW THE BAND SLOWLY DRFTG
SOUTH OVRNGT AND WEAKENING. CRNT KTYX 88D IMAGES SHOW A SOMEWHAT
MORE DISORGANIZED BAND NOW IN THE ADVISORY AREA AND INDEED VERY
SLOWLY MVG SOUTH. SOMEWHAT CNRND THAT ANOTHER SPOKE ROTATING ARND
THE UPR LOW COULD DELAY THE SWRD MVMT AND QUICKLY GIVE PART OF THE
FCST AREA NEAR ADVISORY SNOW THIS EVE. AIR STILL PLENTY COLD WITH
-14C AIR CORE OVER THE LAKE. HWVR...SINKING MOTION SHOWN IN THE
SNDGS CONTS TO LWR THE INV PTNLY WEAKENING THE BAND REGARDLESS OF
THE FLOW. ATTM WILL CONT WITH THE ADVISORY FOR NRN ONEIDA AND PUT
ACCUMS JUST BLO CRITERIA IN NRN ONONDAGA AND SRN ONEIDA.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
LE WILL LINGER INTO THU WITH CONTD COLD AIR AND NW FLOW. HIPRES
SFC AND ALOFT FNLY BLDS IN FOR FRI AS THE CLSD LOW DRIFTS EAST IN
RESPONSE TO THE DVLPG COMPLEX OVER THE CNTR OF THE COUNTRY. FRI
LOOKS SUNNY WITH SLGTLY ABV NRML TEMPS.
COMPLEX SCENARIO AND TRICKY FCST UNFOLDING FOR THE END OF THE SHRT
TERM. YET ANOTHER CLSD LOW OVER THE GREAT LAKES TRIES TO PHASE
WITH A SRN STREAM SHRT WV TRAVELING UP THE EAST CST. MODELS
TYPICALLY HAVE TROUBLE WITH DVLPG LOWS AND THIS IS COMPLCATED BY
THE DFCLTY IN PLACING THE MEANDERING CLSD UPR LOW OVER THE WRN
LAKES. CONSENSUS NOW IS TO DVLP THE SRN STREAM IMPULSE ENOUGH TO
PUSH MORE SUBSTANTIAL PCPN BACK INTO THE SERN ZONES...NAMELY THE
PA AND THE WRN CATS. OTR COMPLICATING FACTOR IS PCPN TYPE WITH A
COMPLETE LACK OF COLD AIR...EVEN OVER NRN NEW ENG. SO...IT LOOKS
VERY MUCH LIKE AN EARLY SPRING LIKE SCENARIO WITH MIXED PCPN...OR
LRG VLY/HILL DFRNCS. CNRT WWE FCST GIVE THE SERN ZONES A 4 TO 6
INCH ACCUM...2 TO 4 ELSEWHERE. WILL CONT A MENTION IN THE HWO FOR
NOW AND XPCT CONTG CHGS TO THE FCST AS THE WEEKEND APRCHS.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
1 PM UPDATE...
BLOCKY PATTERN WITH TWO CLOSED LOWS MOVING THROUGH IN THE LONG
TERM. BOTH APPEAR TO BE MINOR FOR THE CWA. THE FIRST WILL BE
FRIDAY TO SUNDAY. THE UPPER LEVEL LOW WILL BE IN THE GREAT LAKES
SAT NGT WITH A NOREASTER FORMING. MOST MODELS HAVE A NEAR MISS.
THE TROF GOES NEGATIVE TILT WHICH SLOWS THE SNOW FROM EXITING
UNTIL SUNDAY. A WEAK LAKE RESPONSE ON THE BACK SIDE OF THE STORM
SUNDAY NIGHT TO MONDAY. LATE MONDAY A LARGE AREA OF HIGH PRESSURE
MOVES IN AT THE SFC AND ALOFT.
TUESDAY TO WEDNESDAY DO IT ALL OVER AGAIN WITH ANOTHER STACKED
LOW. THE EURO HANDLES THIS STORM SLOWER WITH THE LOW IN ILLINOIS
TUES MORN MOVG TO SSM WED. WARM AIR COMES NORTH WITH THE OCCLUDED
FRONT SO PRECIP WILL BE MIXED. THE GFS BRINGS THE STACKED LOW ENE
OVER NY/PA SO A BETTER CHC OF SNOW.
&&
.AVIATION /01Z THURSDAY THROUGH MONDAY/...
A COLD NORTHWEST FLOW WILL PERSIST THROUGH THIS TAF PERIOD
BRINGING A CONTINUATION OF SNOW SHOWERS AND FLURRIES. AN ORGANIZED
AND WELL DEFINED LAKE EFFECT SNOW BAND OFF LAKE ONTARIO WILL
GRADUALLY DROP SOUTH THIS EVENING WHILE WEAKENING.
AT KRME...GENERALLY IFR SNOW SHOWERS WILL CONTINUE THROUGH 04Z
THEN DROP SOUTH OF THE TERMINAL WITH MVFR SNOW SHOWERS EXPECTED
TIL 09Z THEN VFR WITH CIGS AROUND 3,500 FT.
AT KSYR...IFR WITH OCCASIONAL BELOW ALT MIN CONDITIONS THROUGH
04Z. AFTER 08Z CONDITIONS SHOULD IMPROVE TO MVFR SNOW SHOWERS AND
FLURRIES.
AT KITH/KBGM...GENERALLY MVFR CONDITIONS DUE TO CIGS WITH
OCCASIONAL MVFR VSBY RESTRICTIONS IN SNOW SHOWERS LATE TONIGHT
THROUGH THURSDAY.
AT KELM/KAVP...GENERALLY VFR WITH CIGS AROUND 4K FT AND SNOW FLURRIES.
WEST WINDS 10-15 KNOTS WITH GUSTS AROUND 25 KNOTS DURING THE
DAYLIGHT HOURS ON THURSDAY.
.OUTLOOK...
THU NGT/FRI MORN...VFR.
FRI AFTN TO SAT NGT...MVFR/IFR IN MIXED PCPN.
SUN...VFR...MAYBE MVFR IN NY WITH LAKE ENHANCED SNOW SHOWERS.
MON...VFR.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...DGM
NEAR TERM...DGM/DJP
SHORT TERM...DGM
LONG TERM...TAC
AVIATION...RRM
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
310 PM EST TUE FEB 19 2013
.SYNOPSIS...
A COLD FRONT WILL SWING THROUGH THE REGION THIS EVENING ALONG WITH
WIDESREAD...ALBEIT LIGHT RAIN AND SNOW. TEMPERATURES TREND COOLER
BY TOMORROW INTO LATE WEEK AS LOW PRESSURE DRIFTS SLOWLY ACROSS THE
AREA. THIS WILL ALSO BRING PLENTY OF CLOUDS AND SCATTERED TO
NUMEROUS SNOW SHOWERS TO OUR AREA...ESPECIALLY ACROSS THE NORTHERN
MOUNTAINS. THE UNSETTLED PATTERN WITH CHANCES OF RAIN AND SNOW
SHOWERS CONTINUES INTO NEXT WEEKEND AS TEMPERATURES TREND MILDER.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
AS OF 310 PM EST TUESDAY...FORECAST REMAINS ON TRACK FOR THIS
EVENING INTO TONIGHT AS SURFACE COLD FRONT CURRENTLY ACROSS
WESTERN NEW YORK PROGRESSES STEADILY EAST ALONG WITH A PERIOD OF
LIGHT RAIN AND/OR SNOW. LOW TO MID LEVEL AIRMASS CONTINUES TO RUN
QUITE DRY AHEAD OF THE PRIMARY FRONTAL ZONE AND ASSOCIATED
PRECIPITATION SUCH THAT ONCE PRECIPITATION ARRIVES WET BULB
COOLING PROCESSES SHOULD ALLOW MANY AREAS TO TRANSITION TO A LIGHT
RAIN/SNOW MIX OR ALL SNOW. THAT SAID PLENTY OF AREAS IN THE
CHAMPLAIN VALLEY LIKELY TO HOLD AROUND THE 40F UNTIL PCPN ARRIVES
SO AN HOUR OR TWO OF PLAIN RAIN CERTAINLY POSSIBLE. MAIN IDEA IS
THAT PCPN WILL BE LIGHT WITH MODEL BLENDED QPF PROGS IN GOOD
AGREEMENT SHOWING ANYWHERE FROM A TENTH TO A QUARTER INCH ACROSS
OUR AREA WITH PERHAPS EVEN LESS IN THE NORTHERN CHAMPLAIN VALLEY
DUE TO SHADOWING EFFECTS. THUS ANY SNOW ACCUMULATIONS WILL BE
LIGHT AS WELL AND GENERALLY BELOW 3 INCHES. AS FRONTAL ZONE CLEARS
EAST LATER THIS EVENING LOWER TO MID LEVEL FLOW WILL TREND WEST TO
SOUTHWESTERLY UNDER MODEST COLD THERMAL ADVECTION AND A GRADUAL
COOLING OF SURFACE TEMPERATURES. SNOW SHOWER COVERAGE WILL ALSO
WANE OVERNIGHT. DID OPT TO STAY ON THE MILD SIDE OF MOS/RAW
MACHINE NUMBERS GIVEN AMPLE CLOUD COVER AND A MIXED NOCTURNAL
BOUNDARY LAYER OFFERING VALUES MAINLY IN THE 20S.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
AS OF 310 PM EST TUESDAY...BY WEDNESDAY PARENT OCCLUSION CURRENTLY
ACROSS THE NORTHERN GREAT LAKES WILL DRIFT SLOWLY INTO THE SLV AND
SOUTHERN QUEBEC KEEPING PLENTY OF CLOUDS ACROSS OUR AREA ALONG
WITH SCATTERED SNOW SHOWERS...MAINLY CENTRAL AND NORTH. WITH LOW
TO MID LEVEL FLOW REMAINING WESTERLY HIGHEST COVERAGE SHOULD BE
CONFINED TO THE HIGHER TERRAIN OF THE GREENS AND PORTIONS OF THE
SOUTHWESTERN ADIRONDACKS WHERE CONDITIONS WILL BE MARGINALLY
CONDUCIVE FOR SOME ENHANCED LAKE SNOWS. HIGHS NEAR LATE WINTER
SEASONAL LEVELS FROM 25 TO 32.
BY WEDNESDAY NIGHT INTO THE FIRST HALF OF THURSDAY OVERALL COVERAGE
OF SNOW SHOWERS SHOULD INCREASE ACROSS OUR CENTRAL AND NORTHERN
COUNTIES AS OCCLUSION TRUDGES SLOWLY EAST AND INCREASINGLY
MOIST/CYCLONIC FLOW DEVELOPS ACROSS THE AREA. A DISTINCT SURFACE
TROUGH PASSAGE WILL OCCUR DURING THIS PERIOD ALONG WITH DEVELOPING
BLOCKED FLOW AND WARM THERMAL ADVECTION ALOFT. THIS ALL SPELLS A
DECENT 12-18 HR PERIOD OF LIGHT TO MODERATE SNOWFALL IN OUR FAVORED
UPSLOPE AREAS WHERE SOME MODEST ACCUMULATIONS WILL CERTAINLY BE
POSSIBLE ABOVE 2000 FEET AND AT OUR NRN RESORTS. LOW LEVEL FLOW IS
WEST-NORTHWESTERLY ENOUGH HOWEVER THAT ACCUMULATIONS IN THE NRN
VALLEYS WILL BE CONSIDERABLY LESS. FURTHER SOUTH ONLY FLURRIES
EXPECTED. ONCE AGAIN KEPT OVERNIGHT LOWS ON THE MILD SIDE OF
GUIDANCE GIVEN AMPLE CLOUD COVER...MAINLY 10 TO 20. HIGHS BY
THURSDAY A TAD COOLER THAN WEDNESDAY...MAINLY 20S.
ON THURSDAY NIGHT SNOW SHOWER COVERAGE WANES AND COMES TO AN END
OVERNIGHT AS UPPER LOW PULLS EAST AND FAIRLY AMPLIFIED LOW TO MID
LEVEL RIDGING BUILDS EASTWARD. THUS SKIES SHOULD TREND CLEAR TO
PTLY CLOUDY AS LOWS BOTTOM OUT IN THE UPPER SINGLE DIGITS INTO THE
TEENS.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
AS OF 300 PM EST TUESDAY...LARGE SCALE PATTERN WL CONT TO BE
PROGRESSIVE ACRS THE CONUS WITH SEVERAL SYSTEMS IMPACTING OUR CWA.
FIRST SYSTEM ARRIVES ON SATURDAY...WITH GFS/ECMWF AND GEM SHOWING
NO PHASING WITH NORTHERN/SOUTHERN STREAMS AND LIMITED IMPACT ACRS
OUR FA. NORTHERN STREAM ENERGY/MOISTURE WL TRACK ACRS THE CENTRAL
GREAT LAKES...WHILE SOUTHERN STREAM S/W ENERGY WL SLIDE TO OUR
SOUTH ACRS THE MID ATLANTIC STATES. THIS PLACES OUR CWA IN REGION
OF MID LVL DEFORMATION...ALONG WITH AN INVERTED TROF LIKE
FEATURE AT THE SFC. THIS COMBINED WITH SOME 850 TO 500MB RH WL
PRODUCE CHCS FOR LIGHT PRECIP SAT/SUN. LATEST THERMAL PROFILES SUGGEST
RAIN/SNOW VALLEYS AND MAINLY SNOW IN THE MTNS. BETTER S/W ENERGY
ROTATES THRU OUR CWA ON SUNDAY...WITH POTENTIAL FOR SOME ENHANCED
PRECIP. OVERALL...QPF BTWN THE TWO SYSTEMS WL BE LIGHT AND
SNOWFALL MINOR. PROGGED 85H TEMPS BTWN -4C AND -6C SUPPORT HIGHS
MAINLY IN THE 30S. OVERNIGHT LOWS WL BE MUCH ABOVE NORMAL WITH
EXPECTED CLOUDS...THINKING MAINLY IN THE 20S TO NEAR 30F CPV. HIGH
PRES AND DRY WEATHER RETURNS FOR MONDAY BEFORE NEXT SYSTEM ARRIVES
BY MIDWEEK. THIS LOOKS SIMILAR TO OUR EVENT TODAY/TONIGHT...WITH
CLOSED 5H/7H CIRCULATION TRACKING TO OUR NORTH WITH AN OCCLUDED
SFC TROF MOVING ACRS OUR REGION. STILL SOME UNCERTAINTY WITH
TIMING/IMPACT...BUT TEMPS LOOK TO BE ABOVE NORMAL GOING INTO NEXT
WEEK...WITH HIGHS M30S MTNS TO L40S VALLEYS.
&&
.AVIATION /20Z TUESDAY THROUGH SUNDAY/...
THROUGH 18Z WEDNESDAY...CNRT RADAR SHOWS A BAND OF MIXED PRECIP
MOVING TWD NORTHERN NY ATTM. DWPTS AHEAD OF THIS PRECIP ARE VERY
DRY...SO LEADING EDGE IS VIRGA AND NOT REACHING THE GROUND. IN
ADDITION...EXPECT THIS PRECIP TO COOL THE COLUMN ENOUGH TO SUPPORT
A RAIN CHANGING TO SNOW MIXTURE...ESPECIALLY AT SLK/MPV WITH
OCCASIONAL IFR LIKELY. BASED ON HRRR AND LATEST RADAR
TRENDS...THINKING IFR CONDITIONS WL ARRIVE IN SLK/MSS BY
19Z...WITH MVFR AT PBG/BTV/RUT BTWN 20-21Z...AND AFT 21Z AT MPV.
UPSTREAM OBS SHOW SOME IP/RA INITIALLY...BUT THIS QUICKLY CHANGES
TO -SN WITH VIS RANGING BTWN 1-3SM...WHICH IS SIMILAR TO WHAT WL
HAPPEN ACRS OUR TAF SITES. OTHERWISE...BAND OF DEEPEST MOISTURE
AND BEST LIFT WL BE NORTHEAST OF OUR TAF SITES BY 00Z
TONIGHT...WITH MAINLY SCATTERED SNOW SHOWERS ANTICIPATED...AND
OCCASIONAL MVFR CONDITIONS POSSIBLE. SOUTHERLY WINDS WL CONT TO BE
GUSTY BTWN 15 AND 25 KNTS...BEFORE PRECIP ARRIVES. SFC COLD FRNT
NEAR KBUF WL CAUSE A WIND SHIFT TO THE SOUTHWEST/WEST THIS
EVENING...WITH SOME POTENTIAL HIGHER GUSTS OVERNIGHT. MVFR WITH
OCCASIONAL IFR CONDITIONS IN -SHSN ACTIVITY WL BE POSSIBLE
OVERNIGHT AT SLK...ELSEWHERE MVFR/VFR CONDITIONS ARE EXPECTED.
OUTLOOK 18Z WEDNESDAY THROUGH FRIDAY...
A VERTICALLY STACKED AREA OF LOW PRES AND THE ASSOCIATED CYCLONIC
UPSLOPE FLW WL RESULT IN OCCASIONAL SNOW SHOWER ACTIVITY FROM 18Z
WEDS THRU 06Z FRIDAY. THIS COMBINED WITH SEVERAL EMBEDDED S/W`S
WL PRODUCE PERIODS OF SNOW SHOWERS WITH OCCASIONAL IFR LIKELY AT
SLK/MPV AND MVFR CONDITIONS POSSIBLE AT BTV/MSS/RUT/PBG. THE
GREATEST CHC FOR IFR CONDITIONS AT BTV/RUT/PBG WL BE ON THURSDAY.
OTHERWISE...SFC RIDGE AND IMPROVING CONDITIONS ARE ANTICIPATED ON FRIDAY.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...NONE.
NY...NONE.
&&
$$
SYNOPSIS...JMG
NEAR TERM...JMG
SHORT TERM...JMG
LONG TERM...TABER
AVIATION...TABER
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
303 PM EST TUE FEB 19 2013
.SYNOPSIS...
A LARGE UPPER LEVEL TROUGH OF LOW PRESSURE WILL MOVE EAST FROM THE GREAT
LAKES REGION TODAY AND BE SLOW TO CLEAR OUR AREA OVER THE NEXT COUPLE
OF DAYS. AS A RESULT...EXPECT UNSETTLED WEATHER WITH LIGHT RAIN OR SNOW
DEVELOPING THIS AFTERNOON AND CONTINUING AS SNOW SHOWERS LATER TONIGHT.
SOME MINOR SNOW ACCUMULATIONS ARE EXPECTED. MORE SNOW SHOWERS ARE EXPECTED
WEDNESDAY THROUGH THURSDAY...ESPECIALLY OVER THE MOUNTAINS...WHERE SOME
SNOW ACCUMULATIONS ARE EXPECTED.
&&
.NEAR TERM /UNTIL 7 PM THIS EVENING/...
AS OF 1223 PM EST TUESDAY...VERY MINOR UPDATES TO HOURLY
TEMPERATURES AND SFC DEWPOINTS INTO EARLY EVENING PER LATEST
OBSERVATIONAL DATA. READINGS ALL OVER THE PLACE DEPENDING ON
LOCALE AND/OR DEGREE OF MIXING...RANGING FROM THE UPPER 20S TO THE
MID 40S. STILL LOOKING AT LIGHT RAIN/SNOW DEVELOPING ACROSS OUR
NRN NY COUNTIES THIS AFTERNOON...AND INTO VERMONT LATE OR BY EARLY
EVENING AS COLD FRONT ACROSS WESTERN NY STATE MAKES ITS WAY EAST.
REST OF FCST REMAINS IN GOOD SHAPE. ENJOY YOUR AFTERNOON.
&&
.SHORT TERM /7 PM THIS EVENING THROUGH THURSDAY/...
AS OF 333 AM EST TUESDAY...DRY SLOT ASSOCIATED WITH THE UPPER LOW
WILL MOVE INTO THE AREA TONIGHT AND THIS WILL HELP BRING AN END TO
MOST OF THE PRECIPITATION AFTER MIDNIGHT. SOME LINGERING SNOW
SHOWERS ARE EXPECTED OVER THE MOUNTAINS AND PARTS OF THE SOUTHERN
SAINT LAWRENCE VALLEY WHERE SOME LAKE EFFECT SNOW MAY DEVELOP OFF
OF LAKE ONTARIO AND MOVE INTO THE AREA. MOST LOCATIONS SHOULD SEE
A DUSTING TO 2 INCHES OF SNOW TONIGHT WITH SLIGHTLY HIGHER AMOUNTS
IN THE MOUNTAINS. THE UPPER LOW MOVES ACROSS THE AREA ON WEDNESDAY
AND REACHES NOVA SCOTIA BY THURSDAY. FAVORABLE NORTHWEST FLOW
ALOFT DEVELOPS WITH THIS SCENARIO. THUS LOOKING AT ISOLATED TO
SCATTERED SNOW SHOWERS IN THE LARGER VALLEYS WEDNESDAY THROUGH
THURSDAY AND NUMEROUS SNOW SHOWERS FOR THE MOUNTAINS. COULD SEE
ANYWHERE FROM 1 TO 4 INCHES OF NEW SNOW IN THE MOUNTAINS BY LATE
IN THE DAY ON THURSDAY. LOOK FOR A COOLING TREND THROUGH MUCH OF
THE PERIOD. HIGH TEMPERATURES WILL STILL BE AROUND NORMAL ON
WEDNESDAY...BUT WILL BE SEVERAL DEGREES BELOW NORMAL BY THURSDAY.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
AS OF 300 PM EST TUESDAY...LARGE SCALE PATTERN WL CONT TO BE
PROGRESSIVE ACRS THE CONUS WITH SEVERAL SYSTEMS IMPACTING OUR CWA.
FIRST SYSTEM ARRIVES ON SATURDAY...WITH GFS/ECMWF AND GEM SHOWING
NO PHASING WITH NORTHERN/SOUTHERN STREAMS AND LIMITED IMPACT ACRS
OUR FA. NORTHERN STREAM ENERGY/MOISTURE WL TRACK ACRS THE CENTRAL
GREAT LAKES...WHILE SOUTHERN STREAM S/W ENERGY WL SLIDE TO OUR
SOUTH ACRS THE MID ATLANTIC STATES. THIS PLACES OUR CWA IN REGION
OF MID LVL DEFORMATION...ALONG WITH AN INVERTED TROF LIKE
FEATURE AT THE SFC. THIS COMBINED WITH SOME 850 TO 500MB RH WL
PRODUCE CHCS FOR LIGHT PRECIP SAT/SUN. LATEST THERMAL PROFILES SUGGEST
RAIN/SNOW VALLEYS AND MAINLY SNOW IN THE MTNS. BETTER S/W ENERGY
ROTATES THRU OUR CWA ON SUNDAY...WITH POTENTIAL FOR SOME ENHANCED
PRECIP. OVERALL...QPF BTWN THE TWO SYSTEMS WL BE LIGHT AND
SNOWFALL MINOR. PROGGED 85H TEMPS BTWN -4C AND -6C SUPPORT HIGHS
MAINLY IN THE 30S. OVERNIGHT LOWS WL BE MUCH ABOVE NORMAL WITH
EXPECTED CLOUDS...THINKING MAINLY IN THE 20S TO NEAR 30F CPV. HIGH
PRES AND DRY WEATHER RETURNS FOR MONDAY BEFORE NEXT SYSTEM ARRIVES
BY MIDWEEK. THIS LOOKS SIMILAR TO OUR EVENT TODAY/TONIGHT...WITH
CLOSED 5H/7H CIRCULATION TRACKING TO OUR NORTH WITH AN OCCLUDED
SFC TROF MOVING ACRS OUR REGION. STILL SOME UNCERTAINTY WITH
TIMING/IMPACT...BUT TEMPS LOOK TO BE ABOVE NORMAL GOING INTO NEXT
WEEK...WITH HIGHS M30S MTNS TO L40S VALLEYS.
&&
.AVIATION /20Z TUESDAY THROUGH SUNDAY/...
THROUGH 18Z WEDNESDAY...CNRT RADAR SHOWS A BAND OF MIXED PRECIP
MOVING TWD NORTHERN NY ATTM. DWPTS AHEAD OF THIS PRECIP ARE VERY
DRY...SO LEADING EDGE IS VIRGA AND NOT REACHING THE GROUND. IN
ADDITION...EXPECT THIS PRECIP TO COOL THE COLUMN ENOUGH TO SUPPORT
A RAIN CHANGING TO SNOW MIXTURE...ESPECIALLY AT SLK/MPV WITH
OCCASIONAL IFR LIKELY. BASED ON HRRR AND LATEST RADAR
TRENDS...THINKING IFR CONDITIONS WL ARRIVE IN SLK/MSS BY
19Z...WITH MVFR AT PBG/BTV/RUT BTWN 20-21Z...AND AFT 21Z AT MPV.
UPSTREAM OBS SHOW SOME IP/RA INITIALLY...BUT THIS QUICKLY CHANGES
TO -SN WITH VIS RANGING BTWN 1-3SM...WHICH IS SIMILAR TO WHAT WL
HAPPEN ACRS OUR TAF SITES. OTHERWISE...BAND OF DEEPEST MOISTURE
AND BEST LIFT WL BE NORTHEAST OF OUR TAF SITES BY 00Z
TONIGHT...WITH MAINLY SCATTERED SNOW SHOWERS ANTICIPATED...AND
OCCASIONAL MVFR CONDITIONS POSSIBLE. SOUTHERLY WINDS WL CONT TO BE
GUSTY BTWN 15 AND 25 KNTS...BEFORE PRECIP ARRIVES. SFC COLD FRNT
NEAR KBUF WL CAUSE A WIND SHIFT TO THE SOUTHWEST/WEST THIS
EVENING...WITH SOME POTENTIAL HIGHER GUSTS OVERNIGHT. MVFR WITH
OCCASIONAL IFR CONDITIONS IN -SHSN ACTIVITY WL BE POSSIBLE
OVERNIGHT AT SLK...ELSEWHERE MVFR/VFR CONDITIONS ARE EXPECTED.
OUTLOOK 18Z WEDNESDAY THROUGH FRIDAY...
A VERTICALLY STACKED AREA OF LOW PRES AND THE ASSOCIATED CYCLONIC
UPSLOPE FLW WL RESULT IN OCCASIONAL SNOW SHOWER ACTIVITY FROM 18Z
WEDS THRU 06Z FRIDAY. THIS COMBINED WITH SEVERAL EMBEDDED S/W`S
WL PRODUCE PERIODS OF SNOW SHOWERS WITH OCCASIONAL IFR LIKELY AT
SLK/MPV AND MVFR CONDITIONS POSSIBLE AT BTV/MSS/RUT/PBG. THE
GREATEST CHC FOR IFR CONDITIONS AT BTV/RUT/PBG WL BE ON THURSDAY.
OTHERWISE...SFC RIDGE AND IMPROVING CONDITIONS ARE ANTICIPATED ON FRIDAY.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...NONE.
NY...NONE.
&&
$$
SYNOPSIS...EVENSON
NEAR TERM...JMG
SHORT TERM...EVENSON
LONG TERM...TABER
AVIATION...TABER
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
1256 PM EST TUE FEB 19 2013
.SYNOPSIS...
A LARGE UPPER LEVEL TROUGH OF LOW PRESSURE WILL MOVE EAST FROM THE GREAT
LAKES REGION TODAY AND BE SLOW TO CLEAR OUR AREA OVER THE NEXT COUPLE
OF DAYS. AS A RESULT...EXPECT UNSETTLED WEATHER WITH LIGHT RAIN OR SNOW
DEVELOPING THIS AFTERNOON AND CONTINUING AS SNOW SHOWERS LATER TONIGHT.
SOME MINOR SNOW ACCUMULATIONS ARE EXPECTED. MORE SNOW SHOWERS ARE EXPECTED
WEDNESDAY THROUGH THURSDAY...ESPECIALLY OVER THE MOUNTAINS...WHERE SOME
SNOW ACCUMULATIONS ARE EXPECTED.
&&
.NEAR TERM /UNTIL 7 PM THIS EVENING/...
AS OF 1223 PM EST TUESDAY...VERY MINOR UPDATES TO HOURLY
TEMPERATURES AND SFC DEWPOINTS INTO EARLY EVENING PER LATEST
OBSERVATIONAL DATA. READINGS ALL OVER THE PLACE DEPENDING ON
LOCALE AND/OR DEGREE OF MIXING...RANGING FROM THE UPPER 20S TO THE
MID 40S. STILL LOOKING AT LIGHT RAIN/SNOW DEVELOPING ACROSS OUR
NRN NY COUNTIES THIS AFTERNOON...AND INTO VERMONT LATE OR BY EARLY
EVENING AS COLD FRONT ACROSS WESTERN NY STATE MAKES ITS WAY EAST.
REST OF FCST REMAINS IN GOOD SHAPE. ENJOY YOUR AFTERNOON.
&&
.SHORT TERM /7 PM THIS EVENING THROUGH THURSDAY/...
AS OF 333 AM EST TUESDAY...DRY SLOT ASSOCIATED WITH THE UPPER LOW
WILL MOVE INTO THE AREA TONIGHT AND THIS WILL HELP BRING AN END TO
MOST OF THE PRECIPITATION AFTER MIDNIGHT. SOME LINGERING SNOW
SHOWERS ARE EXPECTED OVER THE MOUNTAINS AND PARTS OF THE SOUTHERN
SAINT LAWRENCE VALLEY WHERE SOME LAKE EFFECT SNOW MAY DEVELOP OFF
OF LAKE ONTARIO AND MOVE INTO THE AREA. MOST LOCATIONS SHOULD SEE
A DUSTING TO 2 INCHES OF SNOW TONIGHT WITH SLIGHTLY HIGHER AMOUNTS
IN THE MOUNTAINS. THE UPPER LOW MOVES ACROSS THE AREA ON WEDNESDAY
AND REACHES NOVA SCOTIA BY THURSDAY. FAVORABLE NORTHWEST FLOW
ALOFT DEVELOPS WITH THIS SCENARIO. THUS LOOKING AT ISOLATED TO
SCATTERED SNOW SHOWERS IN THE LARGER VALLEYS WEDNESDAY THROUGH
THURSDAY AND NUMEROUS SNOW SHOWERS FOR THE MOUNTAINS. COULD SEE
ANYWHERE FROM 1 TO 4 INCHES OF NEW SNOW IN THE MOUNTAINS BY LATE
IN THE DAY ON THURSDAY. LOOK FOR A COOLING TREND THROUGH MUCH OF
THE PERIOD. HIGH TEMPERATURES WILL STILL BE AROUND NORMAL ON
WEDNESDAY...BUT WILL BE SEVERAL DEGREES BELOW NORMAL BY THURSDAY.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
AS OF 333 AM EST TUESDAY...UPSLOPE SNOW SHOWERS ONGOING AT THE BEGINNING
OF THURSDAY NIGHT...BUT WINDING DOWN TOWARDS FRIDAY MORNING. FRIDAY
AND THE FIRST PART OF FRIDAY NIGHT WILL FEATURE QUIET WEATHER WITH
SURFACE HIGH PRESSURE IN CONTROL AND UPPER LEVEL RIDGE OVER THE REGION
AS WELL. A PAIR OF LOW PRESSURE SYSTEMS WILL THEN IMPACT THE NORTH COUNTRY
WITH THE WEAKER LOW PASSING NORTH OF OUR FORECAST AREA...AND THE STRONGER
LOW WELL OFF THE COAST. ECMWF BRINGS NORTHERN STREAM LOW ACROSS OUR
FORECAST AREA...MERGING WITH THE SOUTHERN STREAM LOW. GFS KEEPS THE
LOWS SEPARATE. HARD TO SAY AT THIS POINT HOW MUCH OUR REGION WILL BE
IMPACTED...IF AT ALL. AT THIS POINT HAVE MENTIONED CHANCE FOR SOME RAIN
AND SNOW SHOWERS...MAINLY SATURDAY NIGHT. SURFACE HIGH PRESSURE RIDGES
BACK INTO THE NORTH COUNTRY FOR MONDAY. THEN ANOTHER LOW PRESSURE SYSTEM
APPROACHES THE AREA FOR THE MID WEEK TIME FRAME. FAIRLY ACTIVE PERIOD...THOUGH
NO SIGNIFICANT PRECIPITATION EVENTS TO TALK ABOUT. TEMPERATURES WILL
RUN ABOVE NORMAL THROUGH THE ENTIRE EXTENDED FORECAST PERIOD.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
THROUGH 18Z WEDNESDAY...CNRT RADAR SHOWS A BAND OF MIXED PRECIP
MOVING TWD NORTHERN NY ATTM. DWPTS AHEAD OF THIS PRECIP ARE VERY
DRY...SO LEADING EDGE IS VIRGA AND NOT REACHING THE GROUND. IN
ADDITION...EXPECT THIS PRECIP TO COOL THE COLUMN ENOUGH TO SUPPORT
A RAIN CHANGING TO SNOW MIXTURE...ESPECIALLY AT SLK/MPV WITH
OCCASIONAL IFR LIKELY. BASED ON HRRR AND LATEST RADAR
TRENDS...THINKING IFR CONDITIONS WL ARRIVE IN SLK/MSS BY
19Z...WITH MVFR AT PBG/BTV/RUT BTWN 20-21Z...AND AFT 21Z AT MPV.
UPSTREAM OBS SHOW SOME IP/RA INITIALLY...BUT THIS QUICKLY CHANGES
TO -SN WITH VIS RANGING BTWN 1-3SM...WHICH IS SIMILAR TO WHAT WL
HAPPEN ACRS OUR TAF SITES. OTHERWISE...BAND OF DEEPEST MOISTURE
AND BEST LIFT WL BE NORTHEAST OF OUR TAF SITES BY 00Z
TONIGHT...WITH MAINLY SCATTERED SNOW SHOWERS ANTICIPATED...AND
OCCASIONAL MVFR CONDITIONS POSSIBLE. SOUTHERLY WINDS WL CONT TO BE
GUSTY BTWN 15 AND 25 KNTS...BEFORE PRECIP ARRIVES. SFC COLD FRNT
NEAR KBUF WL CAUSE A WIND SHIFT TO THE SOUTHWEST/WEST THIS
EVENING...WITH SOME POTENTIAL HIGHER GUSTS OVERNIGHT. MVFR WITH
OCCASIONAL IFR CONDITIONS IN -SHSN ACTIVITY WL BE POSSIBLE
OVERNIGHT AT SLK...ELSEWHERE MVFR/VFR CONDITIONS ARE EXPECTED.
OUTLOOK 18Z WEDNESDAY THROUGH FRIDAY...
A VERTICALLY STACKED AREA OF LOW PRES AND THE ASSOCIATED CYCLONIC
UPSLOPE FLW WL RESULT IN OCCASIONAL SNOW SHOWER ACTIVITY FROM 18Z
WEDS THRU 06Z FRIDAY. THIS COMBINED WITH SEVERAL EMBEDDED S/W`S
WL PRODUCE PERIODS OF SNOW SHOWERS WITH OCCASIONAL IFR LIKELY AT
SLK/MPV AND MVFR CONDITIONS POSSIBLE AT BTV/MSS/RUT/PBG. THE
GREATEST CHC FOR IFR CONDITIONS AT BTV/RUT/PBG WL BE ON THURSDAY.
OTHERWISE...SFC RIDGE AND IMPROVING CONDITIONS ARE ANTICIPATED ON FRIDAY.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...NONE.
NY...NONE.
&&
$$
SYNOPSIS...EVENSON
NEAR TERM...JMG
SHORT TERM...EVENSON
LONG TERM...NEILES
AVIATION...TABER
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
1255 PM EST TUE FEB 19 2013
.SYNOPSIS...
COLDER AIR WILL MOVE INTO THE REGION TODAY. HIGH PRESSURE WILL
BUILD ACROSS THE AREA TONIGHT THROUGH THURSDAY. AN ELEVATED WARM
FRONT WILL APPROACH THE AREA THURSDAY NIGHT...BRINGING WITH IT A
WINTRY MIX OF PRECIPITATION.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
SYNOPTIC SCALE PCPN HAS PUSHED EAST OF THE REGION THIS MORNING. WE
WILL FIND OURSELVES IN POST FRONTAL CAA FOR THE REMAINDER OF THE
DAY. LOW LEVEL MOISTURE LOCATED WITHIN THE DENDRITIC GROWTH ZONE
COMBINED WITH STEEPENING LOW LEVEL LAPSE RATES WILL BRING A CHANCE
OF SNOW SHOWERS TO THE REGION...WITH THE GREATEST CHANCE ACROSS THE
NRN ZONES. SNOW AMOUNTS WILL BE LIGHT. THERE HAS BEEN A CONCERN
ABOUT WIND AND WIND GUSTS AS A TIGHT PRESSURE GRADIENT REMAINS.
LATEST MOMENTUM TRANSFER TECHNIQUES SUGGEST WIND GUSTS SHOULD STAY
IN THE 30 TO 35 KNOT RANGE ACROSS THE NORTH AND 25 TO 30 ACROSS
THE SOUTH...SO WILL CONTINUE TO HIGHLIGHT THIS IN THE HWO AND
PERHAPS A SPS PRODUCT. HAVE SLOWED DOWN THE CLEARING ACRS THE SW
INTO THIS EVENING AS LOW LEVEL MOISTURE IS EXPECTED TO LINGER
LONGER.
AS FOR TEMPERATURES...HAVE SIDED MORE WITH THE LATEST RAP WHICH
HAS TEMPERATURES SLOWLY FALLING THROUGHOUT THE DAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
COLD ADVECTION WITH GUSTY WINDS WILL CONTINUE INTO THE
EVENING...WITH A GRADUAL DECREASE IN WIND SPEEDS. ANY LINGERING
SNOW SHOWERS...MAINLY ACROSS THE NORTH...WILL BEGIN TO DIMINISH
DURING THE EVENING AS THE MOISTURE FEED FROM THE GREAT LAKES CUTS
OFF FROM OUR AREA AND HIGH PRESSURE NOSES ITS WAY EASTWARD.
SKIES WILL BEGIN TO CLEAR FROM SOUTHWEST TO NORTHEAST LATE
TONIGHT. THE COLDER AIRMASS MOVING INTO PLACE WILL ALLOW
TEMPERATURES TO DROP INTO THE TEENS ACROSS MOST OF OUR ZONES
TONIGHT.
THE RIDGE AXIS WILL FINALLY BE CENTERED FROM NORTH TO SOUTH ACROSS
THE OHIO VALLEY WEDNESDAY THROUGH THURSDAY. WITH THE EXCEPTION OF
ONGOING MOIST FLOW ACROSS THE LAKES BRINGING CLOUDS TO THE
NORTHEASTERN ZONES ON WEDNESDAY...SKIES WILL BE PARTLY CLOUDY DURING
THIS TIME PERIOD. TEMPERATURES WILL REMAIN SEASONABLY COOL UNDER
THIS RIDGE...WITH MEAN DAYTIME/NIGHTTIME TEMPERATURES RUNNING
ABOUT 10 DEGREES BELOW NORMAL.
THE ATTENTION THEN TURNS TO A STORM SYSTEM LIFTING NORTHWARD
ACROSS THE PLAINS THURSDAY NIGHT. MID LEVEL RIDGING WILL AMPLIFY
DOWNSTREAM OF THIS STORM THURSDAY NIGHT...BRINGING A DEVELOPING
ELEVATED WARM FRONT ACROSS THE REGION. PRECIPITATION WILL SPREAD
ACROSS THE REGION LATE THURSDAY EVENING AND OVERNIGHT THURSDAY
NIGHT...CONTINUING INTO FRIDAY MORNING. MODELS HAVE COME INTO
BETTER AGREEMENT ON THIS TIMING OVER THE PAST COUPLE OF RUNS.
WITH SURFACE HIGH PRESSURE PROVIDING COLD EASTERLY FLOW INTO OUR
AREA AS THE ELEVATED WARM FRONT LIFTS TOWARD THE OHIO
VALLEY...THERE WILL BE THE OPPORTUNITY FOR A PERIOD OF WINTRY
PRECIPITATION TO OCCUR. CURRENT INDICATIONS ARE THAT A SUFFICIENTLY
DEEP WARM LAYER WILL BE PRESENT ACROSS PARTS OF THE FORECAST AREA
TO ALLOW FOR EITHER SLEET OR FREEZING RAIN TO OCCUR AT THE SURFACE
DURING THE OVERNIGHT HOURS THURSDAY NIGHT. THERE WILL BE A
TRANSITION ZONE BETWEEN THE SHALLOWER WARM LAYER ACROSS THE
NORTH...WHERE MOSTLY SLEET WILL BE POSSIBLE...TO THE CENTRAL
ZONES...WHERE MOSTLY FREEZING RAIN WILL BE POSSIBLE...AND THE
SOUTH WHERE SURFACE TEMPERATURES WILL BE ABOVE FREEZING...YIELDING
RAIN. THIS FORECAST IS BASED ON CURRENT MODEL TRENDS AT 60 HOURS
OUT...THEREFORE MORE ADJUSTMENTS WILL BE ON THE WAY AS THE TIME
DRAWS NEARER FOR THIS STORM SYSTEM...AND SUBSEQUENT MODEL RUNS
COME IN. WILL CONTINUE TO HIGHLIGHT THIS SYSTEM IN THE HWO FOR THE
TIME BEING.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
BEST LIFT AND QPF ARE STILL FORECAST TO LIFT N OF THE REGION ON
FRIDAY...AS A WRMFNT GRADUALLY BRINGS IN WARMER AIR ON FRI.
AS MENTIONED YESTERDAY...SECONDARY SYSTEM THAT WAS LIFTING ACROSS
THE SE U.S. OVER THE WEEKEND HAS TRENDED NWD FOR FRI NGT INTO SAT...
SO INTRODUCED CHC POPS FOR THE SE COUNTIES. RIGHT NOW THE PCPN TYPE
LOOKS LIKE RAIN. HIGH PRESSURE LOOKS LIKE IT WILL FINALLY BUILD IN
FOR SUNDAY. ANOTHER CDFNT IS FORECAST TO SWING INTO THE OH VALLEY
MONDAY...BUT THE GFS AND ECMWF ARE SHOWING DIFFERENCES...SO RIGHT
NOW JUST HAVE A MENTION OF CHANCE POPS FOR MONDAY.
THE COOL SE FLOW ON THU WILL KEEP HIGHS IN THE 30S. LOWS THU NGT IN
THE STORM SHOULD RANGE FROM THE MID 20S IN THE N TO LOWER 30S IN NRN
KY. HIGHS FRIDAY SHOULD MAKE THE 40S AS THE REGION GETS WARM
SECTORED. SOME LOCATIONS IN THE NRN KY MIGHT SEE 50S. EXPECT 40S
OVER THE WEEKEND FOR HIGHS WITH LOWS IN THE UPPER 20S TO LOWER 30S
SATURDAY MORNING AND 25 TO 30 SUNDAY MORNING. HIGHS SHOULD BEGIN TO
WARM FOR SUNDAY AND MONDAY REACHING THE MID 40S TO MID 50S BY MONDAY.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
COLD UPPER LEVEL LOW ACROSS THE GREAT LAKES WILL MOVE SLOWLY OFF
TO THE EAST THROUGH THE TAF PERIOD. LOW LEVEL MOIST CYCLONIC FLOW
WILL GRADUALLY BECOME DRIER AND ANTICYCLONIC BY THE END OF THE TAF
PERIOD.
LOW LEVEL MOISTURE COMBINED WITH AN EMBEDDED DISTURBANCE WILL
RESULT IN FLURRIES AND A FEW SNOW SHOWERS THROUGH 00Z.
THEREAFTER...WE SHOULD SEE A DECREASE IN COVERAGE AS THE DISTURBANCE
MOVES EAST AND SHALLOW INSTABILITY DECREASES. CEILINGS FOR THE
MOST PART WILL BE MVFR WITH SOME MVFR VSBYS IN THE SNOW SHOWERS.
MODELS ARE GIVING MIXED SIGNALS AS TO HOW FAST SKIES WILL CLEAR
AND/OR PARTIALLY CLEAR FROM THE SW TO THE NE OVERNIGHT AND WHETHER
ANOTHER BATCH OF STRATOCUMULUS WILL FORM ACRS THE NORTH AND SETTLE
IN TOWARD MORNING. EITHER WAY...STILL WOULD THINK CEILINGS WOULD
REMAIN MVFR AND ABOVE 2000 FEET.
OUTLOOK...A WINTRY MIX IS LIKELY TO OCCUR THURSDAY NIGHT INTO
FRIDAY MORNING WITH SOME SLEET AND ICE ACCUMULATION POSSIBLE. IN
ADDITION MVFR CEILINGS AND VISIBILITIES WILL BE LIKELY WITH A
PERIOD OF IFR CONDITIONS POSSIBLE. MVFR CEILINGS MAY CONTINUE
THROUGH FRIDAY NIGHT AND INTO SATURDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...LATTO
NEAR TERM...HICKMAN
SHORT TERM...LATTO
LONG TERM...HICKMAN
AVIATION...JGL
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
949 AM EST TUE FEB 19 2013
.SYNOPSIS...
COLDER AIR WILL MOVE INTO THE REGION TODAY. HIGH PRESSURE WILL
BUILD ACROSS THE AREA TONIGHT THROUGH THURSDAY. AN ELEVATED WARM
FRONT WILL APPROACH THE AREA THURSDAY NIGHT...BRINGING WITH IT A
WINTRY MIX OF PRECIPITATION.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
SYNOPTIC SCALE PCPN HAS PUSHED EAST OF THE REGION THIS MORNING. WE
WILL FIND OURSELVES IN POST FRONTAL CAA FOR THE REMAINDER OF THE
DAY. LOW LEVEL MOISTURE LOCATED WITHIN THE DENDRITIC GROWTH ZONE
COMBINED WITH STEEPENING LOW LEVEL LAPSE RATES WILL BRING A CHANCE
OF SNOW SHOWERS TO THE REGION...WITH THE GREATEST CHANCE ACROSS THE
NRN ZONES. SNOW AMOUNTS WILL BE LIGHT. THERE HAS BEEN A CONCERN
ABOUT WIND AND WIND GUSTS AS A TIGHT PRESSURE GRADIENT REMAINS.
LATEST MOMENTUM TRANSFER TECHNIQUES SUGGEST WIND GUSTS SHOULD STAY
IN THE 30 TO 35 KNOT RANGE ACROSS THE NORTH AND 25 TO 30 ACROSS
THE SOUTH...SO WILL CONTINUE TO HIGHLIGHT THIS IN THE HWO AND
PERHAPS A SPS PRODUCT. HAVE SLOWED DOWN THE CLEARING ACRS THE SW
INTO THIS EVENING AS LOW LEVEL MOISTURE IS EXPECTED TO LINGER
LONGER.
AS FOR TEMPERATURES...HAVE SIDED MORE WITH THE LATEST RAP WHICH
HAS TEMPERATURES SLOWLY FALLING THROUGHOUT THE DAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
COLD ADVECTION WITH GUSTY WINDS WILL CONTINUE INTO THE
EVENING...WITH A GRADUAL DECREASE IN WIND SPEEDS. ANY LINGERING
SNOW SHOWERS...MAINLY ACROSS THE NORTH...WILL BEGIN TO DIMINISH
DURING THE EVENING AS THE MOISTURE FEED FROM THE GREAT LAKES CUTS
OFF FROM OUR AREA AND HIGH PRESSURE NOSES ITS WAY EASTWARD.
SKIES WILL BEGIN TO CLEAR FROM SOUTHWEST TO NORTHEAST LATE
TONIGHT. THE COLDER AIRMASS MOVING INTO PLACE WILL ALLOW
TEMPERATURES TO DROP INTO THE TEENS ACROSS MOST OF OUR ZONES
TONIGHT.
THE RIDGE AXIS WILL FINALLY BE CENTERED FROM NORTH TO SOUTH ACROSS
THE OHIO VALLEY WEDNESDAY THROUGH THURSDAY. WITH THE EXCEPTION OF
ONGOING MOIST FLOW ACROSS THE LAKES BRINGING CLOUDS TO THE
NORTHEASTERN ZONES ON WEDNESDAY...SKIES WILL BE PARTLY CLOUDY DURING
THIS TIME PERIOD. TEMPERATURES WILL REMAIN SEASONABLY COOL UNDER
THIS RIDGE...WITH MEAN DAYTIME/NIGHTTIME TEMPERATURES RUNNING
ABOUT 10 DEGREES BELOW NORMAL.
THE ATTENTION THEN TURNS TO A STORM SYSTEM LIFTING NORTHWARD
ACROSS THE PLAINS THURSDAY NIGHT. MID LEVEL RIDGING WILL AMPLIFY
DOWNSTREAM OF THIS STORM THURSDAY NIGHT...BRINGING A DEVELOPING
ELEVATED WARM FRONT ACROSS THE REGION. PRECIPITATION WILL SPREAD
ACROSS THE REGION LATE THURSDAY EVENING AND OVERNIGHT THURSDAY
NIGHT...CONTINUING INTO FRIDAY MORNING. MODELS HAVE COME INTO
BETTER AGREEMENT ON THIS TIMING OVER THE PAST COUPLE OF RUNS.
WITH SURFACE HIGH PRESSURE PROVIDING COLD EASTERLY FLOW INTO OUR
AREA AS THE ELEVATED WARM FRONT LIFTS TOWARD THE OHIO
VALLEY...THERE WILL BE THE OPPORTUNITY FOR A PERIOD OF WINTRY
PRECIPITATION TO OCCUR. CURRENT INDICATIONS ARE THAT A SUFFICIENTLY
DEEP WARM LAYER WILL BE PRESENT ACROSS PARTS OF THE FORECAST AREA
TO ALLOW FOR EITHER SLEET OR FREEZING RAIN TO OCCUR AT THE SURFACE
DURING THE OVERNIGHT HOURS THURSDAY NIGHT. THERE WILL BE A
TRANSITION ZONE BETWEEN THE SHALLOWER WARM LAYER ACROSS THE
NORTH...WHERE MOSTLY SLEET WILL BE POSSIBLE...TO THE CENTRAL
ZONES...WHERE MOSTLY FREEZING RAIN WILL BE POSSIBLE...AND THE
SOUTH WHERE SURFACE TEMPERATURES WILL BE ABOVE FREEZING...YIELDING
RAIN. THIS FORECAST IS BASED ON CURRENT MODEL TRENDS AT 60 HOURS
OUT...THEREFORE MORE ADJUSTMENTS WILL BE ON THE WAY AS THE TIME
DRAWS NEARER FOR THIS STORM SYSTEM...AND SUBSEQUENT MODEL RUNS
COME IN. WILL CONTINUE TO HIGHLIGHT THIS SYSTEM IN THE HWO FOR THE
TIME BEING.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
BEST LIFT AND QPF ARE STILL FORECAST TO LIFT N OF THE REGION ON
FRIDAY...AS A WRMFNT GRADUALLY BRINGS IN WARMER AIR ON FRI.
AS MENTIONED YESTERDAY...SECONDARY SYSTEM THAT WAS LIFTING ACROSS
THE SE U.S. OVER THE WEEKEND HAS TRENDED NWD FOR FRI NGT INTO SAT...
SO INTRODUCED CHC POPS FOR THE SE COUNTIES. RIGHT NOW THE PCPN TYPE
LOOKS LIKE RAIN. HIGH PRESSURE LOOKS LIKE IT WILL FINALLY BUILD IN
FOR SUNDAY. ANOTHER CDFNT IS FORECAST TO SWING INTO THE OH VALLEY
MONDAY...BUT THE GFS AND ECMWF ARE SHOWING DIFFERENCES...SO RIGHT
NOW JUST HAVE A MENTION OF CHANCE POPS FOR MONDAY.
THE COOL SE FLOW ON THU WILL KEEP HIGHS IN THE 30S. LOWS THU NGT IN
THE STORM SHOULD RANGE FROM THE MID 20S IN THE N TO LOWER 30S IN NRN
KY. HIGHS FRIDAY SHOULD MAKE THE 40S AS THE REGION GETS WARM
SECTORED. SOME LOCATIONS IN THE NRN KY MIGHT SEE 50S. EXPECT 40S
OVER THE WEEKEND FOR HIGHS WITH LOWS IN THE UPPER 20S TO LOWER 30S
SATURDAY MORNING AND 25 TO 30 SUNDAY MORNING. HIGHS SHOULD BEGIN TO
WARM FOR SUNDAY AND MONDAY REACHING THE MID 40S TO MID 50S BY MONDAY.
&&
.AVIATION /15Z TUESDAY THROUGH SATURDAY/...
THE COLD FRONT IS CURRENTLY PUSHING INTO CENTRAL OHIO AND WILL BE
EAST OF ALL OF THE TAF SITES BY 12Z. COLD AIR MOVING QUICKLY IN
BEHIND THE FRONT IS CHANGING PCPN OVER TO SNOW FOR A HALF HOUR OR
SO BEFORE TAPERING OFF. THIS COULD AFFECT KCMH/KLCK BRIEFLY AT THE
START OF THE TAF PERIOD WITH SOME IFR CIGS/VSBYS POSSIBLE.
OTHERWISE...EXPECT MVFR CIGS TO HANG IN THROUGH THE DAY WITH A FEW
SNOW SHOWERS OR FLURRIES POSSIBLE...PRIMARILY AT THE NORTHERN TAF
SITES. THE LOW LEVELS WILL BEGIN TO DRY OUT FROM THE SOUTHWEST
OVERNIGHT. THIS SHOULD ALLOW FOR AT LEAST SOME PARTIAL CLEARING TO
DEVELOP THROUGH THE OVERNIGHT HOURS FROM SOUTHWEST TO NORTHEAST
ACROSS THE AREA. CAA PATTERN TODAY WILL ALLOW FOR GUSTY WEST
WINDS TO PERSIST THROUGH THIS AFTERNOON...BEFORE GRADUALLY
DECREASING OVERNIGHT.
OUTLOOK...A WINTRY MIX IS LIKELY TO OCCUR THURSDAY NIGHT INTO
FRIDAY MORNING WITH SOME SNOW AND ICE ACCUMULATION POSSIBLE. IN
ADDITION MVFR CEILINGS AND VISIBILITIES WILL BE LIKELY WITH A
PERIOD OF IFR CONDITIONS POSSIBLE. MVFR CEILINGS MAY CONTINUE
THROUGH FRIDAY NIGHT AND INTO SATURDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...LATTO
NEAR TERM...HICKMAN
SHORT TERM...LATTO
LONG TERM...SITES
AVIATION...JGL
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
1247 AM EST TUE FEB 19 2013
.SYNOPSIS...
A STRONG COLD FRONT WILL CROSS THE OHIO VALLEY TONIGHT. HIGH
PRESSURE WILL SETTLE OVER THE MIDWEST WEDNESDAY AND THE RIDGE WILL
WORK INTO THE OHIO VALLEY WEDNESDAY NIGHT. AN ELEVATED WARM FRONT
WILL MOVE NORTH THROUGH THE AREA INTO THE GREAT LAKES REGION ON
THURSDAY NIGHT AND FRIDAY.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
A COLD FRONT WAS MOVING ACROSS ILLINOIS LATE THIS EVENING. THIS
BOUNDARY WILL TRACK ACROSS THE REGION OVERNIGHT AND BE NEAR THE
EASTERN EDGE OF THE FORECAST AREA BY DAYBREAK. SHOWERS AHEAD OF
THE FRONT WERE MOVING INTO THE WESTERN COUNTIES AND WILL CONTINUE
EAST. HRRR AND RAP GUIDANCE HAVE BEEN SUGGESTING THAT SHOWERS WILL
COME IN A COUPLE OF WAVES. INITIALLY ACTIVITY WILL BE WIDESPREAD
BUT THEN DIMINISH IN COVERAGE LATER TONIGHT. APPEARS THAT A NARROW
LINE COULD THEN COME THROUGH WITH THE ACTUAL BOUNDARY. SOUTH WINDS
WILL REMAIN GUSTY THROUGH THE NIGHT. BUT STRONGER GUSTS HAVE BEEN
OCCURRING IMMEDIATELY AHEAD OF THE PRECIPITATION WHERE LIGHTER MID
LEVEL ECHOES HAVE BEEN FALLING INTO DRIER AIR. TEMPERATURES SHOULD
REMAIN QUITE MILD THROUGH MOST OF THE NIGHT WITH ONLY A SLIGHT
DROP UNTIL THE FRONT MOVES THROUGH AND THEN READINGS WILL START
TO FALL QUICKLY.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH WEDNESDAY NIGHT/...
COLD AIR BEHIND THE FRONTAL PASSAGE IN THE MORNING WILL RESULT IN
FALLING TEMPERATURES DURING THE DAY. NOT TOO MUCH MOISTURE WILL BE
AROUND BUT SOME SCATTERED SNOW SHOWERS WILL OCCUR OVER THE
NORTHERN HALF OF THE CWA TUESDAY AFTERNOON IN THE CYCLONIC FLOW
CAPTURING SOME MOISTURE OFF OF LAKE MICHIGAN AND INTERACTING WITH
THE THERMAL DIFFERENCES AND COLD AIR ALOFT.
SKIES SHOULD CLEAR OVERNIGHT AS NORTHWEST WINDS CONTINUE TO PUSH
COLDER AIR INTO THE REGION.
FAIR WEATHER CU WILL POP UP ON WEDNESDAY AND AS THE RIDGE OF HIGH
PRESSURE SETTLES OVER THE OHIO VALLEY IT WILL SET UP A TYPICAL
PATTERN FOR RADIATIONAL COOLING. TEMPERATURES TUESDAY NIGHT AND
WEDNESDAY NIGHT WILL BE IN THE TEENS ON BOTH NIGHTS BUT OCCUR FOR
DIFFERENT REASONS...ADVECTION ON WED MORNING AND RADIATION THURS
MORNING.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
FIRST PART OF THE FORECAST PERIOD WILL BE BUSY AS A STORM SYSTEM
LIFTS OUT OF THE PLAINS. AREA OF HIGH PRESSURE WILL BE CENTERED
ACROSS THE REGION THURSDAY MORNING. 12Z MODEL RUNS ARE SHOWING THE
HIGH WILL BE SLOWER IN RETREATING THURSDAY...WHICH WILL DELAY THE
ONSET OF THE PRECIPITATION THU AFTN. SO HAVE BACKED OFF TO JUST SLGT
CHC POPS SW OF CVG FOR THU. WITH THE HIGH HOLDING STRONGER...THU IS
LOOKING COOLER AND THEREFORE THE OVERALL MODEL PROFILES LOOK COLDER.
THIS IS INDICATING MORE SNOW AND POSSIBLY FREEZING RAIN AND A SLOWER
CHANGE OVER TO LIQUID RAIN LATE THU NGT INTO FRI.
BEST LIFT AND QPF ARE STILL FORECAST TO LIFT N OF THE REGION ON
FRIDAY...AS A WRMFNT GRADUALLY BRINGS IN WARMER AIR ON FRI.
AS MENTIONED YESTERDAY...SECONDARY SYSTEM THAT WAS LIFTING ACROSS
THE SE U.S. OVER THE WEEKEND HAS TRENDED NWD FOR FRI NGT INTO SAT...
SO INTRODUCED CHC POPS FOR THE SE COUNTIES. RIGHT NOW THE PCPN TYPE
LOOKS LIKE RAIN. HIGH PRESSURE LOOKS LIKE IT WILL FINALLY BUILD IN
FOR SUNDAY. ANOTHER CDFNT IS FORECAST TO SWING INTO THE OH VALLEY
MONDAY...BUT THE GFS AND ECMWF ARE SHOWING DIFFERENCES...SO RIGHT
NOW JUST HAVE A MENTION OF CHANCE POPS FOR MONDAY.
THE COOL SE FLOW ON THU WILL KEEP HIGHS IN THE 30S. LOWS THU NGT IN
THE STORM SHOULD RANGE FROM THE MID 20S IN THE N TO LOWER 30S IN NRN
KY. HIGHS FRIDAY SHOULD MAKE THE 40S AS THE REGION GETS WARM
SECTORED. SOME LOCATIONS IN THE NRN KY MIGHT SEE 50S. EXPECT 40S
OVER THE WEEKEND FOR HIGHS WITH LOWS IN THE UPPER 20S TO LOWER 30S
SATURDAY MORNING AND 25 TO 30 SUNDAY MORNING. HIGHS SHOULD BEGIN TO
WARM FOR SUNDAY AND MONDAY REACHING THE MID 40S TO MID 50S BY MONDAY.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
COLD FRONT IS EVIDENT ON RADAR PUSHING ACROSS WESTERN INDIANA
ATTM. CURRENT TIMING HAS IT TO THE WESTERN TAF SITES BETWEEN 09Z
AND 10Z AND THE EASTERN TAF SITES AROUND 11Z TO 1130Z. WIDESPREAD
PCPN WILL CONTINUE OUT AHEAD OF THE FRONT WITH VFR CIGS DROPPING
TO MVFR A COUPLE OF HOURS AHEAD OF FROPA. WE HAD SOME ENHANCED
HIGHER GUSTS ALONG THE LEADING EDGE OF THE PCPN DUE IN PART TO
THE DRY LOW LEVELS. NOW THAT WE HAVE MOISTENED UP...EXPECT GUSTS
GENERALLY IN THE 25 TO 30 KNOT RANGE AHEAD OF THE FRONT. A NARROW
LINE OF STRONGER SHOWERS RIGHT WITH THE FRONT COULD BRIEFLY DROP
VSBYS TO IFR BUT RAIN SHOULD THEN END QUICKLY AS DRIER AIR MOVES
IN BEHIND THE FRONT. WINDS WILL SWING AROUND TO THE WEST AND
REMAIN GUSTY THROUGH THE REST OF THE DAY WITH CIGS GENERALLY
REMAINING MVFR.
OUTLOOK...A WINTRY MIX IS LIKELY TO OCCUR THURSDAY NIGHT INTO
FRIDAY MORNING WITH SOME SNOW AND ICE ACCUMULATION POSSIBLE. IN
ADDITION MVFR CEILINGS AND VISIBILITIES WILL BE LIKELY WITH A
PERIOD OF IFR CONDITIONS POSSIBLE. MVFR CEILINGS MAY CONTINUE
THROUGH FRIDAY NIGHT AND INTO SATURDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...WIND ADVISORY UNTIL 2 AM EST EARLY THIS MORNING FOR OHZ026-034-
035-042>046-051>056-060>065-070>074-077>082-088.
KY...WIND ADVISORY UNTIL 2 AM EST EARLY THIS MORNING FOR KYZ092-093-
096>100.
IN...NONE.
&&
$$
SYNOPSIS...FRANKS
NEAR TERM...
SHORT TERM...FRANKS
LONG TERM...SITES
AVIATION...JGL
AREA FORECAST DISCUSSION
NWS MEDFORD OR
922 AM PST TUE FEB 19 2013
.DISCUSSION...THERE ARE TWO MAIN ITEMS OF FOCUS WITH THE FORECAST.
THE FIRST IS THE AMOUNT AND LOCATION OF SNOW SHOWERS THAT WILL
OCCUR DURING THE REMAINDER OF TODAY INTO THE EARLY EVENING. THE
SECOND IS THE STRENGTH AND TIMING OF A COLD FRONT AND POST-FRONTAL
SHOWERS FROM LATE FRIDAY INTO EARLY SATURDAY. WINTER WEATHER
ADVISORIES ARE IN EFFECT FOR MUCH OF THE AREA THROUGH 4 PM. THE
MAJORITY OF PRECIPITATION WILL OCCUR THROUGH NOON THEN SNOW
SHOWERS WILL GRADUALLY TAPER OFF INTO AROUND 7 PM. THE SNOW LEVEL
IS NEAR 1500 FEET THIS MORNING AND WILL RISE TO 2000 TO 2500 FEET
WITH THE DAY-TIME HEATING. THE RECENTLY ARRIVED 12Z NAM AND 12Z
GFS ARE IN LINE WITH THE CURRENT FORECAST.
THERE WILL ALSO BE A WEAK FRONTAL SYSTEM WEDNESDAY NIGHT INTO
EARLY THURSDAY MORNING WHICH WILL LIKELY PRODUCE LESS THAN AN INCH
OF SNOW.
THE FOLLOWING SYSTEM LATE FRIDAY INTO SATURDAY COULD BE THE
STRONGEST OF THE WEEK. BUT THE 12Z GFS SOLUTION BEARS SOME
SIMILARITY TO WHAT HAS OCCURRED THIS MORNING. THIS INCLUDES A
TROUGH TRACKING SOUTHEAST WITH A FOCUS FOR THE PRECIPITATION ON
THE WEST SIDE OF THE CASCADES.
THE CURRENT LONGWAVE PATTERN LOOKS TO PERSIST THROUGH DAY 7 WITH
AN ADDITIONAL WEAK FRONTAL SYSTEM SUNDAY NIGHT INTO MONDAY.
&&
.AVIATION...A MIX OF MVFR/VFR CEILINGS ACROSS THE AREA THIS
MORNING WITH LOCAL IFR/MOUNTAIN OBSCURATIONS IN HEAVIER SHRA/SHSN.
ISOLATED THUNDERSTORMS ARE POSSIBLE JUST ABOUT ANYWHERE WEST OF
THE CASCADES THROUGH THIS AFTERNOON, BUT THE BETTER CHANCE WILL BE
ALONG THE COAST. SHOWERS WILL DIMINISH ACROSS THE AREA LATER THIS
AFTERNOON AND EVENING AS LOW PRESSURE MOVES SOUTHWARD INTO
CALIFORNIA. EXPECT MIXED MVFR/VFR CEILINGS TO PREVAIL OVERNIGHT.
SPILDE
&&
.PREV DISCUSSION... /ISSUED 237 AM PST TUE FEB 19 2013/
DISCUSSION...COOLING CLOUD TOPS AT THE LEADING EDGE OF THE UPPER
COLD POOL ARE MOVING ONSHORE NOW AS A VIGOROUS UPPER LOW SPINS ITS
WAY INTO OUR AREA. SHOWERS WILL INCREASE IN COVERAGE AND INTENSITY
OVER THE COAST AND INTO INTERIOR WEST SIDE SECTIONS THROUGH DAWN.
SURFACE TEMPERATURES ARE CURRENTLY PERILOUSLY CLOSE TO COLD ENOUGH
FOR SNOW IN MANY LOCATIONS, BUT BOTH THE NAM AND RAP FORECAST
SOUNDINGS MAINTAIN A LAYER OF ABOVE FREEZING TEMPERATURES THROUGH
THE MORNING. WILL BE FORCING A RAIN/SNOW MIX INTO THE WEATHER
GRIDS THIS MORNING OVER ELEVATIONS ABOVE 1000 FEET, BUT AM NOT
EXPECTING ANY ACCUMULATION, IN FACT, IT MAY BE ALL RAIN.
THE GOING WINTER WEATHER HEADLINES LOOK OK TO CONTINUE, ESPECIALLY
OVER THE KALMIOPSIS AND WESTERN SISKIYOU COUNTY AS THE MODELS
BRING A SLUG OF MOISTURE INTO THE MOUNTAINS THERE TODAY. ON THE
EAST SIDE, IT`S A BIT MORE TENUOUS. UPSLOPE SNOW WILL CONTINUE IN
THE WARNERS, BUT SNOW OVER THE VALLEYS WILL BE MUCH LIGHTER WITH
MINIMAL IMPACTS. THE ADVISORIES ARE MOSTLY CONFINED TO THE
MOUNTAINS ANYWAY, SO WILL LET THEM RIDE. THE OTHER ASPECT OF
TODAY`S SYSTEM IS THE INSTABILITY, WHICH LOOKS TO BE PRETTY GOOD,
ESPECIALLY OVER THE WATERS. THE CENTER OF THE UPPER COLD POOL (500
MB TEMPS OF -36C) MOVES OVER THE RELATIVELY WARMER WATERS THIS
MORNING AND THEN INTO NW CALIFORNIA THIS AFTERNOON. AS A RESULT,
WE COULD SEE SOME LIGHTNING OVER THE WATERS AND IMMEDIATE COAST.
SIMILAR INSTABILITY WILL ALSO BE PRESENT INLAND, AND WHILE THE LOW
LEVELS WILL PROBABLY BE TOO COOL TO PRODUCE THE SORT OF UPDRAFT
NEEDED FOR LIGHTNING TODAY, I DECIDED IT WAS WORTH MENTIONING OVER
THE CASCADES AND WEST SIDE.
THIS SYSTEM MOVES INLAND TONIGHT WITH SHOWERS DECREASING QUICKLY.
WE STAY IN COOL NW FLOW THROUGH WEDNESDAY THEN ANOTHER SYSTEM
BRINGS PRECIPITATION AND LOW SNOW LEVELS WEDNESDAY NIGHT INTO
THURSDAY. THIS SYSTEM IS WEAKER AND MUCH LESS WET, SO I DOUBT
HEADLINES WILL BE NECESSARY.
THE BIGGER EVENT LOOKS TO BE ON TAP FOR FRIDAY NIGHT INTO
SATURDAY. AS OF NOW, THIS SYSTEM LOOKS TO BE THE WETTEST, COLDEST
AND WINDIEST WE`VE SEEN IN SOME TIME. THE MOUNTAINS AND EAST SIDE
WILL ALMOST CERTAINLY GET SIGNIFICANT SNOW WITH THIS ONE. IT WILL
BE COLD ENOUGH FOR SNOW DOWN INTO THE LOWER VALLEYS ON THE BACK
SIDE, BUT AS ALWAYS IT WILL COME DOWN TO WHETHER THERE IS ENOUGH
PRECIPITATION LEFT WHEN THE COLD AIR ARRIVES. IT`S TOO EARLY TO
SAY FOR SURE, BUT EVERYONE SHOULD JUST BE AWARE THAT LOW ELEVATION
SNOW IS POSSIBLE FRIDAY NIGHT INTO SATURDAY. I WOULD EXPECT WINTER
AND POSSIBLY WIND HEADLINES WITH THIS SYSTEM.
YET ANOTHER SYSTEM IS SLATED FOR SUNDAY NIGHT INTO MONDAY AS THE
PROGRESSIVE NORTHWEST FLOW PATTERN CONTINUES. -WRIGHT
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...WINTER WEATHER ADVISORY UNTIL 4 PM PST THIS AFTERNOON FOR
ORZ031.
WINTER WEATHER ADVISORY UNTIL 4 PM PST THIS AFTERNOON ABOVE 2500
FEET FOR FOR ORZ024.
CA...WINTER WEATHER ADVISORY UNTIL 4 PM PST THIS AFTERNOON FOR
CAZ085.
WINTER WEATHER ADVISORY UNTIL 4 PM PST THIS AFTERNOON ABOVE 2500
FEET FOR FOR CAZ082-083.
WINTER WEATHER ADVISORY UNTIL 4 PM PST THIS AFTERNOON ABOVE 2500
FEET FOR FOR CAZ080.
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL
2 AM PST FRIDAY FOR PZZ350-356-370-376.
SMALL CRAFT ADVISORY FOR WINDS UNTIL 10 AM PST THIS MORNING FOR
PZZ370.
SMALL CRAFT ADVISORY FOR WINDS UNTIL 1 PM PST THIS AFTERNOON FOR
PZZ376.
$$
DW/NSK
AREA FORECAST DISCUSSION
NWS MEDFORD OR
237 AM PST TUE FEB 19 2013
.DISCUSSION...COOLING CLOUD TOPS AT THE LEADING EDGE OF THE UPPER
COLD POOL ARE MOVING ONSHORE NOW AS A VIGOROUS UPPER LOW SPINS ITS
WAY INTO OUR AREA. SHOWERS WILL INCREASE IN COVERAGE AND INTENSITY
OVER THE COAST AND INTO INTERIOR WEST SIDE SECTIONS THROUGH DAWN.
SURFACE TEMPERATURES ARE CURRENTLY PERILOUSLY CLOSE TO COLD ENOUGH
FOR SNOW IN MANY LOCATIONS, BUT BOTH THE NAM AND RAP FORECAST
SOUNDINGS MAINTAIN A LAYER OF ABOVE FREEZING TEMPERATURES THROUGH
THE MORNING. WILL BE FORCING A RAIN/SNOW MIX INTO THE WEATHER
GRIDS THIS MORNING OVER ELEVATIONS ABOVE 1000 FEET, BUT AM NOT
EXPECTING ANY ACCUMULATION, IN FACT, IT MAY BE ALL RAIN.
THE GOING WINTER WEATHER HEADLINES LOOK OK TO CONTINUE, ESPECIALLY
OVER THE KALMIOPSIS AND WESTERN SISKIYOU COUNTY AS THE MODELS
BRING A SLUG OF MOISTURE INTO THE MOUNTAINS THERE TODAY. ON THE
EAST SIDE, IT`S A BIT MORE TENUOUS. UPSLOPE SNOW WILL CONTINUE IN
THE WARNERS, BUT SNOW OVER THE VALLEYS WILL BE MUCH LIGHTER WITH
MINIMAL IMPACTS. THE ADVISORIES ARE MOSTLY CONFINED TO THE
MOUNTAINS ANYWAY, SO WILL LET THEM RIDE. THE OTHER ASPECT OF
TODAY`S SYSTEM IS THE INSTABILITY, WHICH LOOKS TO BE PRETTY GOOD,
ESPECIALLY OVER THE WATERS. THE CENTER OF THE UPPER COLD POOL (500
MB TEMPS OF -36C) MOVES OVER THE RELATIVELY WARMER WATERS THIS
MORNING AND THEN INTO NW CALIFORNIA THIS AFTERNOON. AS A RESULT,
WE COULD SEE SOME LIGHTNING OVER THE WATERS AND IMMEDIATE COAST.
SIMILAR INSTABILITY WILL ALSO BE PRESENT INLAND, AND WHILE THE LOW
LEVELS WILL PROBABLY BE TOO COOL TO PRODUCE THE SORT OF UPDRAFT
NEEDED FOR LIGHTNING TODAY, I DECIDED IT WAS WORTH MENTIONING OVER
THE CASCADES AND WEST SIDE.
THIS SYSTEM MOVES INLAND TONIGHT WITH SHOWERS DECREASING QUICKLY.
WE STAY IN COOL NW FLOW THROUGH WEDNESDAY THEN ANOTHER SYSTEM
BRINGS PRECIPITATION AND LOW SNOW LEVELS WEDNESDAY NIGHT INTO
THURSDAY. THIS SYSTEM IS WEAKER AND MUCH LESS WET, SO I DOUBT
HEADLINES WILL BE NECESSARY.
THE BIGGER EVENT LOOKS TO BE ON TAP FOR FRIDAY NIGHT INTO
SATURDAY. AS OF NOW, THIS SYSTEM LOOKS TO BE THE WETTEST, COLDEST
AND WINDIEST WE`VE SEEN IN SOME TIME. THE MOUNTAINS AND EAST SIDE
WILL ALMOST CERTAINLY GET SIGNIFICANT SNOW WITH THIS ONE. IT WILL
BE COLD ENOUGH FOR SNOW DOWN INTO THE LOWER VALLEYS ON THE BACK
SIDE, BUT AS ALWAYS IT WILL COME DOWN TO WHETHER THERE IS ENOUGH
PRECIPITATION LEFT WHEN THE COLD AIR ARRIVES. IT`S TOO EARLY TO
SAY FOR SURE, BUT EVERYONE SHOULD JUST BE AWARE THAT LOW ELEVATION
SNOW IS POSSIBLE FRIDAY NIGHT INTO SATURDAY. I WOULD EXPECT WINTER
AND POSSIBLY WIND HEADLINES WITH THIS SYSTEM.
YET ANOTHER SYSTEM IS SLATED FOR SUNDAY NIGHT INTO MONDAY AS THE
PROGRESSIVE NORTHWEST FLOW PATTERN CONTINUES. -WRIGHT
&&
.AVIATION...LOW PRESSURE SPINNING OFF OF THE PACIFIC NORTHWEST
COASTLINE IS SENDING COLDER AIR AND BANDS OF SHOWERS ACROSS THE
AREA. LATE TONIGHT THROUGH TUESDAY MORNING THE COLD CORE OF THIS
LOW WILL MOVE SOUTHEASTWARD THROUGH THE FORECAST AREA, MOVING
INLAND NEAR CAPE BLANCO AND THEN SOUTH-SOUTHEASTWARD INTO NORTHERN
CALIFORNIA.
A MIX OF MVFR AND VFR CEILINGS ALONG THE COAST IN SHOWERS AND
ACROSS THE EAST SIDE IN SNOW SHOWERS WILL LIKELY TURN TO MVFR ACROSS
THE WEST SIDE INLAND TO ABOUT ROSEBURG AND GRANTS PASS. MOUNTAINS
WILL BECOME OBSCURED IN CLOUDS AND SNOWFALL ACROSS MOST OF THE AREA,
THOUGH PRECIPITATION WILL BE SHOWERY, SO OBSCURATIONS WILL NOT BE
TOTAL. EXPECT MVFR TO LOCAL IFR TO DEVELOP OVER THE AREA FROM ABOUT
12Z TO 18Z TUESDAY AS THE CORE OF THE LOW PRESSURE SYSTEM MOVES
THROUGH AND SNOW LEVELS LOWER TO 2000 TO 3000 FEET, BUT LOCALLY
LOWER IN HEAVIER SHOWERS. ISOLATED THUNDERSTORMS ARE POSSIBLE
THROUGH TUESDAY DAY PRIMARILY ALONG AND NEAR THE COAST. AS THE LOW
MOVES SOUTHWARD TUESDAY AFTERNOON AND EVENING, SHOWERS WILL
PRIMARILY LINGER IN NORTHWEST UPSLOPE AREAS OF THE CASCADES AND
SISKIYOUS WITH MVFR CONDITIONS IN THE VALLEYS AND OBSCURATIONS IN
THOSE FAVORED UPSLOPE MOUNTAINOUS AREAS. OTHER AREAS WILL IMPROVE TO
VFR WITH AT LEAST PARTIAL CLEARING UNDER A LIGHT TO MODERATE NORTH
FLOW. BTL
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...WINTER WEATHER ADVISORY UNTIL 4 PM PST THIS AFTERNOON FOR
ORZ031.
WINTER WEATHER ADVISORY UNTIL 4 PM PST THIS AFTERNOON ABOVE 2500
FEET FOR FOR ORZ024.
CA...WINTER WEATHER ADVISORY UNTIL 4 PM PST THIS AFTERNOON FOR
CAZ085.
WINTER WEATHER ADVISORY UNTIL 4 PM PST THIS AFTERNOON ABOVE 2500
FEET FOR FOR CAZ080.
WINTER WEATHER ADVISORY UNTIL 4 PM PST THIS AFTERNOON ABOVE 2500
FEET FOR FOR CAZ082-083.
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL
2 AM PST FRIDAY FOR PZZ350-356-370-376.
SMALL CRAFT ADVISORY FOR WINDS UNTIL 1 PM PST THIS AFTERNOON FOR
PZZ376.
SMALL CRAFT ADVISORY FOR WINDS UNTIL 10 AM PST THIS MORNING FOR
PZZ370.
$$
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
937 PM CST WED FEB 20 2013
.UPDATE...
RADAR AND REPORTS INDICATE SOME LIGHT SLEET CONTINUES TO MOVE
ACROSS FAR SOUTHWESTERN ZONES INTO NORTHERN ALABAMA. MOSAIC RADAR
IMAGERY INDICATES ADDITIONAL SLEET SHOWERS DEVELOPING OVER
NORTHERN MISSISSIPPI INTO WESTERN TENNESSEE...AND SOME OF THESE
MAY ATTEMPT TO MOVE INTO SOUTHWESTERN ZONES OVERNIGHT. WILL LEAVE
IN THE MENTION OF A SLIGHT CHANCE OF SLEET TONIGHT...BUT AS
MENTIONED PREVIOUSLY NO ACCUMULATION IS ANTICIPATED.
FURTHER TO THE NORTH...SKIES HAVE CLEARED ACROSS THE NORTHEAST
HALF OF THE CWA ALLOWING TEMPERATURES TO DROP QUICKLY AS
DEWPOINTS ARE ONLY IN THE LOW TO MID TEENS. HAVE LOWERED MIN TEMPS
IN THIS AREA A DEGREE OR TWO ACCORDINGLY...BUT INCOMING CLOUD
COVER SHOULD NOT ALLOW FOR MUCH MORE OF A DROP THAN THAT. RAIN
STILL ON TRACK TO MOVE INTO THE MID STATE DURING THE AFTERNOON
HOURS ON THURSDAY PER 00Z NAM AND 18Z GFS. ALTHOUGH TEMPERATURES
ARE EXPECTED TO BE ABOVE FREEZING AREAWIDE BY AFTERNOON...LOW
DEWPOINTS/SURFACE WET BULB TEMPERATURES COULD ALLOW PRECIP TO
START OUT BRIEFLY AS LIGHT SLEET ON THE LEADING EDGE.
HOWEVER...ANY SLEET WOULD QUICKLY TRANSITION TO RAIN AS WAA
INTENSIFIES RAPIDLY TOMORROW AFTERNOON.
REST OF FORECAST IS ON TRACK WITH NO OTHER CHANGES MADE.
&&
.PREV DISCUSSION... /ISSUED 638 PM CST WED FEB 20 2013/
UPDATE...
SURFACE OBS REMAIN QUITE CHILLY ACROSS THE MID STATE AT THIS HOUR
WITH TEMPS IN THE UPPER 20S TO MID 30S AND DEWPOINTS WAY DOWN INTO
THE TEENS...WHICH RESULTS IN WET BULB TEMPERATURES GENERALLY IN
THE MID 20S. RADAR IMAGERY CONTINUES TO SHOW A PERSISTENT BAND OF
PRECIP FROM MEM TO MSL...WHICH HAS BEEN PREDOMINATELY SLEET BASED
ON REPORTS WITH EVEN SOME LIGHT SLEET ACCUMULATIONS. AIRMASS
FURTHER TO THE EAST IN THE MID STATE IS MUCH DRIER WITH A PWAT OF
ONLY 0.28 INCHES ON THE OHX 21/00Z SOUNDING...ALTHOUGH THERE HAS
BEEN CONSIDERABLE MOISTENING IN THE 650-450MB LAYER SINCE 12Z.
REMAINS UNLIKELY ANY MEASURABLE PRECIP CAN REACH THE GROUND IN OUR
CWA DUE TO THE VERY DRY LOW LEVELS...BUT LATEST HRRR AND WRF RUNS
DO INDICATE AT LEAST A SLIGHT POTENTIAL FOR SOME SLEET IN OUR
SOUTHWEST ZONES TONIGHT. WILL GO AHEAD AND UPDATE TO ADD LOW
PROBABILITY MENTION OF LIGHT SLEET IN THE SOUTHWEST...BUT NO
IMPACT OR ACCUMULATIONS ARE ANTICIPATED. NO OTHER CHANGES TO
FORECAST ATTM.
THANKS MEG FOR THE COORDINATION.
PREV DISCUSSION... /ISSUED 527 PM CST WED FEB 20 2013/
AVIATION...
EXPECT VFR CONDITIONS AT ALL THREE TAF SITES FOR MOST OF THE TAF
PERIOD. AFTER 12Z CIGS WILL BEGIN TO LOWER SLIGHTLY AND
PRECIPITATION IS EXPECTED TO DEVELOP AFTER 18Z...MAINLY AT CKV AND
BNA. VIS SHOULD DROP TO MVFR INITIALLY...WITH FURTHER DEGRADATION
TO CIGS AND VIS AFTER 00Z FRI.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHAMBURGER
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
638 PM CST WED FEB 20 2013
.UPDATE...
SURFACE OBS REMAIN QUITE CHILLY ACROSS THE MID STATE AT THIS HOUR
WITH TEMPS IN THE UPPER 20S TO MID 30S AND DEWPOINTS WAY DOWN INTO
THE TEENS...WHICH RESULTS IN WET BULB TEMPERATURES GENERALLY IN
THE MID 20S. RADAR IMAGERY CONTINUES TO SHOW A PERSISTENT BAND OF
PRECIP FROM MEM TO MSL...WHICH HAS BEEN PREDOMINATELY SLEET BASED
ON REPORTS WITH EVEN SOME LIGHT SLEET ACCUMULATIONS. AIRMASS
FURTHER TO THE EAST IN THE MID STATE IS MUCH DRIER WITH A PWAT OF
ONLY 0.28 INCHES ON THE OHX 21/00Z SOUNDING...ALTHOUGH THERE HAS
BEEN CONSIDERABLE MOISTENING IN THE 650-450MB LAYER SINCE 12Z.
REMAINS UNLIKELY ANY MEASURABLE PRECIP CAN REACH THE GROUND IN OUR
CWA DUE TO THE VERY DRY LOW LEVELS...BUT LATEST HRRR AND WRF RUNS
DO INDICATE AT LEAST A SLIGHT POTENTIAL FOR SOME SLEET IN OUR
SOUTHWEST ZONES TONIGHT. WILL GO AHEAD AND UPDATE TO ADD LOW
PROBABILITY MENTION OF LIGHT SLEET IN THE SOUTHWEST...BUT NO
IMPACT OR ACCUMULATIONS ARE ANTICIPATED. NO OTHER CHANGES TO
FORECAST ATTM.
THANKS MEG FOR THE COORDINATION.
&&
.PREV DISCUSSION... /ISSUED 527 PM CST WED FEB 20 2013/
AVIATION...
EXPECT VFR CONDITIONS AT ALL THREE TAF SITES FOR MOST OF THE TAF
PERIOD. AFTER 12Z CIGS WILL BEGIN TO LOWER SLIGHTLY AND
PRECIPITATION IS EXPECTED TO DEVELOP AFTER 18Z...MAINLY AT CKV AND
BNA. VIS SHOULD DROP TO MVFR INITIALLY...WITH FURTHER DEGRADATION
TO CIGS AND VIS AFTER 00Z FRI.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHAMBURGER
AREA FORECAST DISCUSSION...UPDATED
NWS CORPUS CHRISTI TX
941 PM CST WED FEB 20 2013
.DISCUSSION...LOWERED POPS A BIT OVER THE SOUTHERN AND WESTERN
AREAS...BUT KEPT THEM PRETTY MUCH THE SAME NORTHEAST AS
CONVERGENCE SHOWERS/STREAMERS STILL SEEM REASONABLE. ADJUSTED
CLOUDS A BIT FOR THIS EVENING. OTHERWISE SAW NO NEED TO MAKE ANY
CHANGES AT THIS TIME. TEMPERATURES ARE LOOKING GOOD AT THIS
TIME...EVEN THE HOURLY TEMPERATURES.
&&
.MARINE...DECIDED TO GO WITH A SCA FOR THE NORTHERN BAYS. IT WILL
BE CLOSE...BUT WILL FIT BETTER WITH SURROUNDING OFFICES. RUC13 AND
NAM12 ARE SHOWING WINDS GOING UP TO 20 KNOTS OR MORE OVER THAT
AREA SO WILL BITE ON THAT.
&&
.PREV DISCUSSION... /ISSUED 550 PM CST WED FEB 20 2013/
DISCUSSION...SEE AVIATION DISCUSSION BELOW FOR THE 00Z TAF`S.
AVIATION...DRIER MID/UPPER LEVELS WILL FILTER ACROSS S TX THROUGH
TONIGHT...HOWEVER LOW LEVEL MOISTURE WILL REMAIN IN PLACE THROUGH
MUCH OF THE NIGHT AHD OF A COLD FRONT. A SLY LOW LEVEL JET WILL
INCREASE TO 45-50KTS WHICH WILL LEAD TO A STRATUS DECK FLUCTUATING
BETWEEN 800-1500FT. PATCHY FOG IS ALSO POSSIBLE BRIEFLY AHD OF
THE FRONTAL BDRY TOWARD SUNRISE. ALI TO VCT MAY SEE THE VSBY DROP
TO AROUND 1SM AT TIMES. MOD TO STRONG S WINDS WILL CLOCK AROUND TO
THE SW AND W THROUGH EARLY TO MID MORNING BECOMING NW TO N BY LATE
MORNING INTO EARLY AFTERNOON AS THE BDRY MOVS ESE ACROSS THE AREA
ON THU. WINDS ARE EXPECTED TO DECREASE THROUGH THE AFTERNOON.
PREV DISCUSSION... /ISSUED 412 PM CST WED FEB 20 2013/
SHORT TERM (TONIGHT THROUGH THURSDAY NIGHT)...UPPER LEVEL
SHORT WAVE TROUGH WILL DEEPEN AND DEVELOP INTO CLOSED LOW AS IT
DIGS FROM SOUTHERN CA AND ACROSS THE TX PANHANDLE THROUGH THE
PERIOD. AS LOW PRESSURE DEEPENS OVER SOUTHWEST TEXAS...SOUTHEAST
WINDS WILL CONTINUE TO INCREASE ACROSS THE REGION TONIGHT.
ADDITIONALLY...A STRONG LLJ OF 40 TO 50KTS WILL DEVELOP OVER THE
EASTERN TWO THIRDS OF THE REGION THIS EVENING AND MOVE EASTWARD
ACROSS THE COASTAL WATERS TONIGHT. EXPECTING WINDS TO MIX TO THE
SURFACE...AND MODERATE TO STRONG ONSHORE FLOW TO DEVELOP ACROSS
THE WATERS. DUE TO THE ELEVATED WINDS AND WIDESPREAD CLOUD
COVER...KEPT MINIMUM TEMPERATURES ON THE WARMER SIDE TONIGHT.
THURSDAY A FRONTAL BOUNDARY WILL APPROACH FROM THE
NORTHWEST...ENTERING THE REGION BY NOON...AND STALL OFFSHORE
THURSDAY EVENING. DRY AIR WILL MOVE IN BEHIND THE FRONT AND
LOW TEMPERATURES WILL BE MUCH COOLER THAN THE NIGHT BEFORE. AS FOR
POPS...MODELS ARE NOW SHOWING MOST OF THE PRECIPITATION OCCURRING
TO THE NORTHEAST OF THE REGION. DID KEEP CHANCE POPS AROUND THE
VICTORIA CROSSROADS AND SLIGHT CHANCE ACROSS MUCH OF THE
REGION...BUT NOT EXPECTING TO GET MUCH OF ANYTHING WIDESPREAD.
LONG TERM (FRIDAY THROUGH WEDNESDAY)...THE EXTENDED FORECAST HAS
CHANGED LITTLE WITH THE 12Z MODEL RUNS. FRIDAY WILL BEGIN WITH HIGH
PRESSURE SURGING INTO THE REGION WITH DRIER AIR ADVECTING INTO SOUTH
TEXAS. WILL KEEP SLIGHT CHANCE TO LOW END CHANCE OF SHOWERS OVER THE
COASTAL WATERS FRIDAY MORNING WHERE LEFT OVER MOISTURE OVERRUN THE
STALLED FRONTAL BOUNDARY. TEMPERATURES WILL BE WARM DURING THE
AFTERNOON ON FRIDAY WITH THE LACK OF COLD AIR ADVECTION ASSOCIATED
WITH THE SURFACE HIGH PRESSURE. FRIDAY NIGHT INTO SATURDAY MORNING
WILL BE COOL...GENERALLY IN THE 40S AND 50S WITH WINDS BECOMING
LIGHT. THE SURFACE RIDGE IS PULLED EASTWARD AND MOVES AWAY FROM
SOUTH TEXAS WITH A WEAK RETURN FLOW DEVELOPING THROUGH THE WEEKEND.
THERE MAY BE ENOUGH MOISTURE RETURN ACROSS THE REGION FOR ISOLATED
SHOWERS AHEAD OF OUR NEXT BOUNDARY ON SUNDAY. A MID/UPPER LEVEL
TROUGH WILL SWEEP THROUGH THE CENTRAL PLAINS AND DRIVE THE FRONT
THROUGH SOUTH TEXAS MONDAY MORNING. THIS WILL ONCE AGAIN BRING
NORTHERLY WINDS AND DRIER CONDITIONS BACK ACROSS SOUTH TEXAS.
AGAIN...JUST A SLIGHT DROP IN AFTERNOON TEMPERATURES BEHIND THIS
BOUNDARY...WITH COOLER OVERNIGHT LOWS INTO TUESDAY MORNING. ONSHORE
FLOW RESUMES AGAIN TUESDAY INTO WEDNESDAY OF NEXT WEEK. OUR THIRD
FRONTAL BOUNDARY IN LINE WILL BE POSSIBLE IN THE MIDDLE OF THE NEXT
WEEK.
FIRE WEATHER...
A FRONTAL BOUNDARY APPROACHING FROM THE NORTHWEST TOMORROW WILL
BRING STRONG WINDS AND LOW RELATIVE HUMIDITIES TO THE RIO GRANDE
PLAINS AND BRUSH COUNTRY. NORTHWEST WINDS WILL RANGE FROM 15 TO
25 MPH WITH GUSTS UP TO 30 MPH AND MINIMUM RELATIVE HUMIDITY
VALUES WILL FALL BETWEEN 15 TO 20 PERCENT DURING THE AFTERNOON. THIS WILL
CREATE POSSIBLE CRITICAL FIRE WEATHER CONDITIONS FOR THE
AREA...AND A RED FLAG WARNING HAS BEEN ISSUED FOR THURSDAY FROM
9AM TO 3PM.
&&
.PRELIMINARY POINT TEMPS/POPS...
CORPUS CHRISTI 68 83 57 78 49 / 20 10 10 10 10
VICTORIA 64 79 50 71 43 / 40 40 10 10 10
LAREDO 65 84 51 79 52 / 10 10 10 0 0
ALICE 67 85 54 78 48 / 10 10 10 10 10
ROCKPORT 68 78 58 72 50 / 30 20 10 20 10
COTULLA 61 79 47 77 46 / 10 10 10 10 0
KINGSVILLE 66 85 53 78 47 / 10 10 10 10 10
NAVY CORPUS 68 81 60 75 54 / 20 10 20 10 10
&&
.CRP WATCHES/WARNINGS/ADVISORIES...
TX...RED FLAG WARNING FROM 9 AM TO 3 PM CST THURSDAY FOR THE
FOLLOWING ZONES: DUVAL...LA SALLE...MCMULLEN...WEBB.
GM...SMALL CRAFT ADVISORY UNTIL 3 PM CST THURSDAY FOR THE FOLLOWING
ZONES: COASTAL WATERS FROM BAFFIN BAY TO PORT ARANSAS OUT
20 NM...COASTAL WATERS FROM PORT ARANSAS TO MATAGORDA SHIP
CHANNEL OUT 20 NM...WATERS FROM BAFFIN BAY TO PORT ARANSAS
FROM 20 TO 60 NM...WATERS FROM PORT ARANSAS TO MATAGORDA
SHIP CHANNEL FROM 20 TO 60 NM.
SMALL CRAFT ADVISORY UNTIL 3 AM CST THURSDAY FOR THE FOLLOWING
ZONES: BAYS AND WATERWAYS FROM BAFFIN BAY TO PORT ARANSAS...
BAYS AND WATERWAYS FROM PORT ARANSAS TO PORT O`CONNOR.
&&
$$
GW/86...SHORT TERM
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
929 PM CST WED FEB 20 2013
.UPDATE...
A MINOR UPDATE TO LOWER RAIN CHANCES THROUGH LATE EVENING INTO THE
FIRST FEW HOURS OF THURSDAY MORNING...AS NORTH TEXAS IS IN A LULL
BETWEEN DISTURBANCES. THE FIRST DISTURBANCE THAT GAVE THE RAIN AND
A LITTLE BIT OF SLEET TO PARTS OF NORTH TEXAS EARLIER TODAY IS
HEADING AWAY FROM THE AREA AND CAUSING WINTER WEATHER PROBLEMS
ACROSS PARTS OF OKLAHOMA INTO ARKANSAS/MISSOURI.
THE MAIN SYSTEM THAT WILL AFFECT NORTH TEXAS BY DAYBREAK THURSDAY
MORNING IS JUST STARTING TO ROTATE OUT OF ARIZONA AND INTO WESTERN
NEW MEXICO AT 9 PM. LINEAR FORCING WAS HELPING TO DEVELOP A LINE
OF STORMS ACROSS FAR SOUTHEAST NEW MEXICO AND TO THE TEXAS STATE
LINE. NOT ALL MODELS ARE IN SUCH AS THE 00Z GFS...HOWEVER THE 00Z
NAM...TEXAS TECH WRF AND HRRR MODELS ARE SHOWING IT WILL BE AFTER
3 AM BEFORE THINGS BEGIN TO GET ACTIVE ACROSS THE WESTERN HALF OF
THE AREA. ONE THING TO NOTE OF THE WRF AND 00Z NAM MODELS HOWEVER
WAS THEY WERE TOO FAR EAST FROM LUBBOCK TO MIDLAND WITH THE
DEVELOPING SQUALL LINE AT MID EVENING.
THE SURFACE WARM FRONT WHICH IS NOW OVER SOUTH-CENTRAL TEXAS WILL
ONLY CREEP NORTH WITH THE BEST NORTHWARD SURGE OCCURRING WEST/SOUTHWEST
OF OUR AREA CLOSER TO THE BETTER HEIGHT FALLS AND SURFACE LOW
CURRENTLY OVER ALPINE AND FAR WEST TEXAS. STRONG 850MB WAA WILL SLIDE
EAST ACROSS WESTERN NORTH TEXAS BETWEEN 3-6 AM...AND THIS WILL BE
THE TIME STORMS AND A FEW SUPERCELLS WILL DEVELOP. BEST CHANCE FOR
SURFACE-BASED SEVERE STORMS WITH DAMAGING WINDS AND TORNADOES WILL
BE IN A LIMITED TIME WINDOW FROM 5AM-9AM AND GENERALLY SOUTH OF A
HAMILTON-WACO-ATHENS OR PALESTINE LINE. WITH 0-6KM SOUTHWESTERLY
SHEAR ON THE ORDER OF 70-90 KTS AND SOMEWHAT VEERED 0-1KM ON THE
ORDER OF 40-50 KTS...SUPERCELLS ARE HIGHLY LIKELY. ELEVATED
SUPERCELLS WILL OCCUR NORTH OF THE WARM FRONT WITH VERY LARGE
HAIL...FREQUENT LIGHTNING...AND HEAVY DOWNPOURS THE MAIN THREATS.
WE WILL CONTINUE TO MONITOR THIS SYSTEM DURING THE OVERNIGHT AND
URGE EVERYONE TO KEEP ON EYE THINGS AS THEY WAKE UP AND BEFORE
HEADING OUT FOR THE MORNING COMMUTE THURSDAY MORNING. SPOTTER AND
HAMS COULD EASILY BE ACTIVATED ACROSS THE WESTERN HALF OF THE CWA
BEFORE SUNRISE.
05/
&&
.AVIATION...
CONDITIONS WILL DETERIORATE TO IFR LATER IN THE EVENING AND REMAIN
SO UNTIL AFTER THE COLD FRONT AND LINE OF CONVECTION PASSES
THROUGH THE TAF SITES.
WE/RE EXPECTING MVFR CONDITIONS TO SPREAD OVER THE METROPLEX SITES
WITHIN THE HOUR...THEN BECOME IFR 05-06Z. KACT WILL BECOME IFR BY
04Z. THERE WILL BE SOME SCTD SHRA AND MAYBE ISOLD TSRA BETWEEN
04-12Z TONIGHT BEFORE THE MAIN LINE OF CONVECTION ARRIVES LATER TONIGHT.
A LINE OF STRONG TO SEVERE THUNDERSTORMS...WITH A POTENTIAL FOR
HAIL UP TO GOLF BALLS AND WINDS UP TO 55 KTS...WILL MOVE ACROSS
OUR TAF SITES...AROUND 12-14Z ACROSS THE METROPLEX AND 14Z AT
KACT. EXPECTING VFR SKIES TO RETURN ABOUT 1 OR 2 HOURS BEHIND THE
COLD FRONT.
A STRONG LOW LEVEL JET WILL SETUP TONIGHT WITH SPEEDS WITHIN THE 2-5
KFT LAYER GENERALLY 40-55 KTS. THUS WE/VE ADDED LLWS TO THE LATE
NIGHT TIME PERIOD FOR ALL SITES.
WINDS WILL BE EASTERLY OVERNIGHT THEN VEERING SOUTHEASTERLY AS THE
COLD FRONT NEARS. EXPECTING SOUTHWESTERLY WINDS BEHIND THE FRONT
ON THURSDAY MORNING AND CONTINUING THROUGH THE AFTERNOON. KDFW
WILL SEE WINDS GO NORTHWESTERLY THURSDAY EVENING. SPEEDS WILL BE
GENERALLY 10-18 KTS EXCEPT DURING TSRA WHEN STRONG AND GUSTY WINDS
MAY DEVELOP. 75
&&
.PREV DISCUSSION... /ISSUED 330 PM CST WED FEB 20 2013/
CLOUDY AND COOL CONDITIONS PERSIST ACROSS THE REGION THIS
AFTERNOON WITH JUST A FEW SCATTERED AREAS OF LIGHT RAIN/SHOWERS
ACROSS THE REGION. THE UPPER LEVEL SYSTEM THAT WE HAVE BEEN
MONITORING TO BRING US STORMS AND A THREAT FOR SEVERE WEATHER
TONIGHT/THURSDAY IS NOW MOVING INTO SOUTHERN ARIZONA. THE
ASSOCIATED PACIFIC FRONT IS ALSO MOVING INTO ARIZONA...AND THIS
ENTIRE SYSTEM HAS QUITE A WAYS TO TRAVEL BEFORE ARRIVING IN NORTH
AND CENTRAL TEXAS.
FOR THE REST OF TODAY AND EARLY TONIGHT...RAIN ACTIVITY WILL BE
ISOLATED TO SCATTERED IN NATURE BUT OVERALL IT WILL BE A QUIET
EVENING. THEREFORE LOWERED POPS FOR THE EVENING HOURS AND ALSO
REMOVED THE MENTION OF THUNDER. THE RAIN ACTIVITY THROUGH THE
NIGHT WILL MAINLY COME FROM INCREASING ISENTROPIC LIFT ASSOCIATED
WITH WARM AIR ADVECTION OVER THE COOL SURFACE BOUNDARY LAYER. MUCH
LATER TONIGHT...LIFT FROM THE APPROACHING UPPER LEVEL LOW WILL
BEGIN TO SPREAD OVER THE REGION AND WILL LIKELY SEE AN INCREASE IN
CONVECTIVE/THUNDERSTORM ACTIVITY DURING THE OVERNIGHT HOURS.
AS THE UPPER LEVEL LOW APPROACHES THE TEXAS PANHANDLE
OVERNIGHT...A LINE OF STORMS IS EXPECTED TO DEVELOP ALONG THE
PACIFIC FRONT AND SWEEP EAST ACROSS THE REGION. THE LATEST HI-RES
AND SHORT TERM GUIDANCE IS NOW SLOWER WITH THE DEVELOPMENT AND
MOVEMENT OF THIS LINE OF STORMS...THUS MADE MINOR ADJUSTMENTS TO
POPS TOMORROW BASED ON THIS SLOWER TIMING. MOST SHORT-TERM
GUIDANCE HAS THE FRONT/LINE OF STORMS ALONG OUR WESTERN BORDER
AROUND 11Z/5 AM CST...GIVE OR TAKE AN HOUR. THIS WOULD PUT THE
LINE OF STORMS ALONG THE I-35 CORRIDOR AROUND MID MORNING AND THEN
MOVING OUT OF OUR EASTERN COUNTIES AROUND MIDDAY. WITH GOOD
AGREEMENT AMONG MANY OF THE MODELS ON THIS SLOWER
TIMING...CONFIDENCE IS FAIRLY HIGH THAT THE SYSTEM WILL TAKE
SLIGHTLY LONGER TO ARRIVE THAN PREVIOUSLY THOUGHT...ESPECIALLY
WITH THE UPPER LEVEL LOW STILL OUT IN ARIZONA.
WITH LARGE SCALE LIFT SPREADING OVER THE AREA OVERNIGHT AND WARM
AIR ADVECTION INCREASING...ALSO EXPECT SCATTERED SHOWER AND
THUNDERSTORM ACTIVITY TO DEVELOP AHEAD OF THE LINE OF STORMS. LIKE
THE STORMS ALONG THE FRONT...THE STORMS AHEAD OF THE FRONT WILL
ALSO BE ELEVATED ABOVE THE COOLER SURFACE BOUNDARY LAYER.
HOWEVER...IT IS POSSIBLE THAT SOME OF THESE EARLY STORMS COULD
ALSO REACH SEVERE LIMITS...IN PARTICULAR SOUTH OF INTERSTATE 20
WHERE MUCAPE WILL BE HIGHER AND LAPSE RATES STEEPER.
HOWEVER...OVERALL THE INSTABILITY OVERNIGHT IT NOT THAT GREAT AND
THE ENVIRONMENT WILL LIKELY REMAIN CAPPED THROUGH MUCH OF THE
NIGHT.
THE GREATER SEVERE THREAT EXISTS WITH THE LINE OF STORMS DUE TO
SUFFICIENT INSTABILITY /MUCAPE VALUES OVER 500 J/KG /...STRONG WIND
SHEAR...AND BETTER LAPSE RATES. IN THIS PARTICULAR
ENVIRONMENT...LARGE HAIL WILL BE THE MAIN THREAT BUT DAMAGING
WINDS WILL ALSO BE POSSIBLE. CLOSER TO DAYBREAK...OR AROUND 6-7
AM...SOME OF THE MODELS DEVELOP SURFACE BASED CAPE UP TO 1000 J/KG
IN OUR SOUTHWESTERN AND SOUTHERN COUNTIES AS THE WARM FRONT LIFTS
INTO THAT AREA AND DEWPOINTS INCREASE INTO THE LOWER 60S. THE NAM
IS MOST AGGRESSIVE WITH THE SURFACE BASED CAPE BUT THE SITUATION
BEARS A CLOSE WATCH AS SURFACE BASED STORMS WILL POSE A TORNADO
THREAT IN THIS STRONGLY SHEARED ENVIRONMENT. WILL HIGHLIGHT A LOW
TORNADO THREAT THURSDAY MORNING ALONG AND SOUTH OF A LINE FROM
HAMILTON TO FAIRFIELD.
STRONG WEST WINDS WILL OCCUR BEHIND THE FRONT TOMORROW AFTERNOON
WHICH WILL RESULT IN TEMPERATURES RECOVERING INTO THE 60S AND
POSSIBLY LOWER 70S. A COLD FRONT WILL MOVE THROUGH THE REGION
THURSDAY NIGHT/EARLY FRIDAY MORNING. THIS WILL RESULT IN COOLER
TEMPS ON FRIDAY AND FREEZING TEMPS ACROSS MUCH OF THE REGION
FRIDAY NIGHT. ANOTHER SHORTWAVE AND UPPER LEVEL TROUGH WILL SWING
ACROSS THE REGION FRIDAY AND SATURDAY BUT THE MOISTURE WILL BE TOO
SCOURED OUT FOR ANY ADDITIONAL RAIN WITH THIS FEATURE. WE WILL
BRIEFLY WARM UP OVER THE WEEKEND BEFORE ANOTHER UPPER LEVEL SYSTEM
MOVES INTO THE PLAINS AND DRIVES A FRONT THROUGH THE REGION ON
MONDAY. SOUTHERLY RETURN FLOW AHEAD OF THIS SYSTEM MAY RESULT IN
SOME SHOWERS AND STORMS SUNDAY AND SUNDAY NIGHT.
82/JLD
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 42 65 33 54 32 / 70 100 5 5 0
WACO, TX 48 67 35 58 31 / 70 90 5 0 0
PARIS, TX 36 59 32 52 27 / 60 90 10 5 0
DENTON, TX 39 64 29 51 25 / 70 100 5 5 0
MCKINNEY, TX 38 64 30 52 28 / 70 100 5 5 0
DALLAS, TX 43 66 34 54 33 / 70 100 5 5 0
TERRELL, TX 41 64 34 55 30 / 60 100 5 5 0
CORSICANA, TX 46 67 37 59 32 / 60 90 10 5 0
TEMPLE, TX 48 69 36 62 33 / 80 90 5 0 0
MINERAL WELLS, TX 43 66 29 55 28 / 80 70 5 5 0
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
75/05
AREA FORECAST DISCUSSION
NWS MIDLAND/ODESSA TX
323 PM CST TUE FEB 19 2013
.DISCUSSION...
WV IMAGERY SHOWS THE UPPER TROUGH ALONG THE WEST COAST NEAR THE
OR/CA BORDER...TRANSITIONING FLOW ALOFT OVER WEST TEXAS/SE NM FROM
ZONAL TO SW AS IT PUSHES THE RIDGE EAST. W/IN THIS FLOW ALOFT IS A
THICK PLUME OF STR MSTR...PUTTING THE KIBOSH ON AFTERNOON HIGHS AND
WINDS OUT WEST. BUFFER AND LATEST RUC SOUNDINGS AT KGDP INDICATE
MUCH LESS MIXING AND HEAVIER CLOUD COVER...SO WE/LL CANCEL THE
CURRENT WIND WARNINGS/ADVISORIES THERE FOR THE AFTERNOON PACKAGE.
IN ITS PLACE...WE/LL INCREASE POPS OVER MUCH OF THE AREA. SHORT
RANGE MODELS ARE ALL CONSISTENT IN BRINGING A SHORTWAVE THRU THE
NORTHERN HALF OVER THE CWA OVERNIGHT...MAINLY NORTH OF I-10/20 UNDER
A NAM-ADVERTISED LFQ OF A H2 125+KT JET. AREA RADARS ALREADY SHOW
SHRA HAS DEVELOPED S OF KELP. FORECAST SOUNDINGS STILL SHOW FAIRLY
DRY SUBCLOUD LAYERS...SO QPF WILL BE LIGHT.
WEDNESDAY...LATEST MODELS HAVE SLOWED THE UPPER TROUGH FROM 24 HRS
AGO...AND BRING IT TO CENTRAL AZ BY 00Z THURSDAY. H7 PRESSURE
GRADIENT INCREASES TO 60M/150NM OVER THE GUADALUPES BY 18Z
WEDNESDAY...W/SFC GRADIENTS INCREASING AFTER 00Z THURSDAY AS A SFC
TROUGH MOVES SOUTH OF THE AREA...AND A LEESIDE SFC TROUGH SINKS INTO
THE SOUTH PLAINS THURSDAY AFTERNOON. AS THE UPPER TROUGH EJECTS
NE. HIGH WINDS WILL BE POSSIBLE THRU THE GUADALUPES FROM WED
AFTERNOON THRU THURSDAY...AND WE/LL ISSUE A WARNING TO COVER THIS
THRU THEN. ELSEWHERE...ADVISORIES WILL BE ISSUED FOR THE ADJACENT
PLAINS...AND FOR THE MTNS SOUTH. BLDU WILL STILL BE
POSSIBLE...DESPITE ANY QPF. W/THIS INCREASED SW FLOW...AND DESPITE
CLOUD COVER/COOLER TEMPS...RH/S OUT WEST SHOULD STILL REACH CRITICAL
LEVELS BY THE AFTERNOON. EAST OF THIS...INSTABILITY WILL BEGIN
INCREASING IN BETTER MOISTURE OVER THE EASTERN ZONES. FORECAST
SOUNDINGS SHOW A CAP...BUT A SHORTWAVE/LIFT AHEAD OF THE TROUGH MAY
BE SUFFICIENT ENOUGH TO KICK OFF A THUNDERSTORM OR TWO DURING THE
LATE MORNING/AFTERNOON. BY 00Z THURSDAY...MODELS SHARPEN UP A
DRYLINE MID-CWA...W/A WARM FRONT AND EVEN THE HINT OF A TRIPLE POINT
EAST. FORECAST SOUNDINGS LOSE THE CAP WEDNESDAY EVENING...FOR
THUNDERSTORM DEVELOPMENT ALONG AND EAST OF THE DRYLINE...W/BEST
CHANCES OVER THE UPPER CONCHO VALLEY. STILL NOT READY TO PULL THE
TRIGGER ON MENTIONING SEVERE STORMS YET...AND WOULD LIKE TO SEE
BETTER MID-LVL LRS. FORECAST SOUNDINGS CONTINUE TO INDICATE 0-6KM
BULK SHEAR OF 70KTS ALONG THE DRYLINE...AND ANY STORMS THAT DO
DEVELOP SHOULD MOVE EAST OUT OF THE AREA AT 40+KTS. THURSDAY INTO
THE EXTENDED CONTINUES TO LOOK DRY AND WINDY. W/THE EJECTION OF THE
UPPER TROUGH...THE ECMWF/CMC BRING IN THE NEXT TROUGH FLAT/FAST
FRIDAY...WHILE THE SLOWER...DEEPER GFS ARRIVES SATURDAY. ALL THREE
MODELS FINISH OUT THE EXTENDED WITH A SERIES OF UPPER LEVEL SYSTEMS
BRUSHING NORTH OF THE AREA...SUGGESTING WIND AND FIRE WX WILL BE
CANDIDATES FOR CONCERN THRU MIDWEEK NEXT WEEK.
&&
.PRELIMINARY POINT TEMPS/POPS...
ANDREWS TX 47 65 36 64 / 70 10 20 0
BIG SPRING TX 44 63 39 62 / 60 20 50 0
CARLSBAD NM 40 70 34 67 / 40 0 0 0
DRYDEN TX 48 67 45 67 / 10 0 0 0
FORT STOCKTON TX 48 76 40 63 / 10 0 0 0
GUADALUPE PASS TX 38 62 27 52 / 40 0 0 0
HOBBS NM 42 65 32 64 / 70 0 20 0
MARFA TX 30 68 25 52 / 10 0 0 0
MIDLAND INTL AIRPORT TX 46 64 38 61 / 50 10 20 0
ODESSA TX 48 67 37 63 / 50 10 20 0
WINK TX 46 74 37 65 / 50 0 10 0
&&
.MAF WATCHES/WARNINGS/ADVISORIES...
NM...FIRE WEATHER WATCH THURSDAY AFTERNOON FOR THE FOLLOWING ZONES...
GUADALUPE MOUNTAINS NP/LINCOLN NF/LNZ...SOUTHEAST
PLAINS/BLM ROSWELL/LNZ.
HIGH WIND WARNING FROM 11 AM WEDNESDAY TO 5 PM MST THURSDAY FOR
THE FOLLOWING ZONES... GUADALUPE MOUNTAINS OF EDDY COUNTY.
RED FLAG WARNING FROM NOON TO 6 PM MST WEDNESDAY FOR THE
FOLLOWING ZONES... GUADALUPE MOUNTAINS NP/LINCOLN NF/LNZ...
SOUTHEAST PLAINS/BLM ROSWELL/LNZ.
WIND ADVISORY FROM 11 AM TO 5 PM MST WEDNESDAY FOR THE FOLLOWING
ZONES... EDDY COUNTY PLAINS.
TX...FIRE WEATHER WATCH FROM THURSDAY AFTERNOON THROUGH THURSDAY
EVENING FOR THE FOLLOWING ZONES... ANDREWS...BORDEN...
CRANE...DAWSON...ECTOR...GAINES...GLASSCOCK...GUADALUPE
MOUNTAINS...HOWARD...LOVING...MARTIN...MIDLAND...PECOS...
REAGAN...REEVES COUNTY AND UPPER TRANS PECOS...UPTON...VAN
HORN AND HIGHWAY 54 CORRIDOR...WARD...WINKLER.
WIND ADVISORY FROM NOON WEDNESDAY TO 6 AM CST THURSDAY FOR THE
FOLLOWING ZONES... BIG BEND AREA...DAVIS/APACHE MOUNTAINS
AREA...MARFA PLATEAU.
HIGH WIND WARNING FROM 11 AM WEDNESDAY TO 5 PM MST THURSDAY FOR
THE FOLLOWING ZONES... GUADALUPE MOUNTAINS.
RED FLAG WARNING FROM 1 PM CST /NOON MST/ TO 7 PM CST /6 PM MST/
WEDNESDAY FOR THE FOLLOWING ZONES... DAVIS/APACHE MOUNTAINS
AREA...GUADALUPE MOUNTAINS...LOVING...MARFA PLATEAU...
PRESIDIO VALLEY...REEVES COUNTY AND UPPER TRANS PECOS...VAN
HORN AND HIGHWAY 54 CORRIDOR.
&&
$$
12/44
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
1148 PM EST MON FEB 18 2013
.SYNOPSIS...
A COLD FRONT IS GOING TO MOVE FROM THE MISSISSIPPI VALLEY TONIGHT
INTO THE CENTRAL APPALACHIANS BY LATE TUESDAY MORNING...AND
THROUGH OUR AREA BY TUESDAY EVENING.
HIGH PRESSURE WILL WORK IN FROM THE UPPER MIDWEST WEDNESDAY
SLIDING EAST OVER THE AREA BY THURSDAY MORNING.
&&
.NEAR TERM /THROUGH TUESDAY/...
AS OF 810 PM EST MONDAY...
CONVECTIVE BAND NOW EAST OF THE MISS RIVER REMAINS THE MAIN
CONCERN LATER TONIGHT AS IT ZIPS EAST AND ENCOUNTERS RESIDUAL
COLD/DRY AIR STILL LOCKED IN ACROSS THE REGION. TIMING/QPF THE
MAIN ASPECTS ACROSS THE WESTERN THIRD BY MORNING...AND EAST OF THE
BLUE RIDGE EARLY TUESDAY. LATEST NAM AND RAP REMAIN A BIT SLOW
WITH INIT ON CURRENT AXIS OF PRECIP TO THE WEST...SO PLANNING TO
STAY FASTER WITH ARRIVAL ESPCLY GIVEN SUCH A STRONG 3H JETLET
PASSING THRU THE BOTTOM OF THE UPPER TROF JUST WEST OF THE
MOUNTAINS BY DAYBREAK. LATEST FORECAST SOUNDINGS SUGGEST QUICK WET
BULBING DOWN TO AN ISOTHERMAL LAYER AROUND FREEZING WESTERN HALF
LATE WITH VERY LITTLE WARM NOSE SUPPORTIVE OF MORE SLEET/SNOW
EXCEPT PERHAPS THE FAR SW WHERE THE BOUNDARY LAYER MAY BE A BIT
WARM FOR LITTLE MORE THAN RAIN/SLEET. LATEST LOCAL RNK WRK ALSO
SHOWING HEAVIER BANDS OF PRECIP FAR WEST AT THE ONSET SO MAIN
CHANGE WAS TO UP QPF ALONG/WEST OF THE I-77 CORRIDOR BY 12Z...AND
BOOST POPS/SNOWFALL FOR THE NW NC RIDGES INTO GRAYSON WHERE 1-2+
INCHES LOOK POSSIBLE BEFORE PRECIP TAPERS OR GOES TO -DZ TUESDAY.
ELSW STILL THINKING A MIXED BAG...BUT LIKELY MORE SNOW IN THE
TYPICAL DEEPER WEDGE AREAS...WITH SOME FREEZING RAIN POSSIBLE
VALLEYS EARLY TUESDAY AFTER SURFACE TEMPS HAVE BEEN BRIEFLY COOLED
BELOW FREEZING.
TIMING EAST OF THE ADVISORY CRITICAL IN WHETHER OR NOT ANYTHING
FROZEN OCCURS OR IS MOSTLY A RAIN EVENT WITH SOME SLEET AT THE
ONSET ESPCLY IF ARRIVAL IS AN HOUR OR TWO AFTER DAYBREAK. COULD
POSSIBLY SEE LOCATIONS ON THE VIRGINIA SIDE...OUT EAST OF THE
HIGHER RIDGES TO HIGHWAY 29...GET A QUICK SLEET/SNOW COATING BUT
ONLY IF PRECIP IS FASTER. OTRW MOSTLY LIGHT QPF AND LIQUID AT
THIS POINT.
SOUTH WINDS JUST AHEAD OF THE FRONT STILL LOOK CLOSE TO WARNING
CRITERIA TAZEWELL/BLF REGION PER LATEST MODEL CROSS SECTIONS.
HOWEVER LIKELY ONLY A QUICK BURST RIGHT AHEAD OF THE PRECIP
LATE GIVEN THE FLOW TURNING MORE SW...AND THEN PERHAPS STRONGER
LATER TUESDAY BEHIND THE FRONT WHEN MOMENTUM TRANSFER IS BETTER
OUTSIDE OF THE RAIN/SNOW. THUS WILL KEEP GUSTS TO HIGH END
ADVISORY WITHIN THE WINTER WEATHER PRODUCT FOR THE OVERNIGHT AT
THIS POINT.
TEMPS SLOW TO FALL THIS EVENING OUTSIDE THE VALLEYS WITH A DECENT
SOUTH WIND KICKING IN WELL AHEAD OF THE FRONT. THEREFORE ADJUSTING
THE TEMP CURVE A BIT TO REFLECT COLDER VALUES MORE WITH PRECIP
LATER THAN EARLY RAD COOLING. HOWEVER DEWPOINTS REMAIN DRY ENOUGH
TO WET BULB DOWN TO THE LOW/MID 30S UNLESS THE WARM ADVECTION IS
JUST TOO STRONG...AND THE INIT PRECIP LIGHT...ALLOWING A QUICK
RISE IN DEWPOINT DEPRESSIONS LATE THUS CUTTING INTO WET BULB
COOLING SOMEWHAT.
PREVIOUS DISCUSSION...
EXPECTING A NUISANCE TYPE WINTER WEATHER EVENT LATE TONIGHT INTO
LATE TUESDAY MORNING...WHICH ALTHOUGH AMOUNTS OF WINTRY WEATHER
WILL NOT BE REACHING OUR ADVISORY LEVELS PER SE...THE MORNING
COMMUTE WILL BE WHEN MOST OF THIS WILL BE OCCURRING...HENCE THE
ADVISORY. NOT TOO IMPRESSED WITH FREEZING RAIN CHANCES...DESPITE
THE STRONG LOW LVL JET ARRIVING LATE TONIGHT. ATTM...MODEL
SOUNDINGS FORECAST ENOUGH DRY AIR AND SUB-FREEZING WET BULBS THAT
WHEN PRECIPITATION ARRIVES ACROSS MOST OF THE AREA IT SHOULD START
AS SNOW. EXCEPTION WILL BE ACROSS THE FAR WRN ZONES WHERE MORE OF
SW WIND WILL HELP KEEP THE LOW LVLS WARMER WITH RAIN MIXING IN.
MADE NO CHANGES TO THE ADVISORY...EXCEPT ADDING THE MENTION OF
HIGHER WIND GUSTS OVER THE TYPICAL AREAS FROM BLF-MOUNT ROGERS.
THE 8H JET OF 60 KNOTS AND SFC WINDS OUT OF THE SSE ARE USUALLY
ENOUGH TO GIVE THE CLINCH RIVER VALLEY/BURKES GARDEN AND OTHER
AREAS AROUND THE MOUNTAIN EMPIRE STRONG WIND GUSTS. ATTM...DO NOT
SEE A HIGH WIND WARNING ALTHOUGH WOULD NOT BE SURPRISED IF PLACES
LIKE MOUNT ROGERS OR BURKES GARDEN EXPERIENCE GUSTS OVER 58 MPH.
SOME SMALL TREES AND LIMBS WILL BE FALLING...WITH ISOLATED POWER
OUTAGES POSSIBLE.
GOING TOWARD THE MODEL MEAN OF THE NAM/GFS SHOWS THE FRONT PUSHING
ACROSS THE BLUE RIDGE BY EARLY AFTERNOON. HAVE PRECIP CHANGING TO
MORE RAIN BEFORE THEN WITH SNOW LINGERING OVER THE HIGHER
ELEVATIONS...BECOMING MORE SHOWERY AFTER FRONTAL PASSAGE. THINGS
DRY OUT BY THE AFTERNOON IN THE SOUTHWEST WITH A QUICK DRYING
ARRIVING ELSEWHERE BY THE END OF THE DAY. WINDS ARE GOING TO SHIFT
WEST AND GUST OVER 40 MPH AT TIMES...BUT NOT GOING WITH WIND
ADVISORY AS 8H WINDS ARE NOT AS STRONG...PER NAM/GFS.
TEMPS WILL BE FALLING QUICK THIS EVENING BEFORE CLOUDS
ARRIVE...THEN STEADY OR RISE AFTER MIDNIGHT BEFORE FALLING AGAIN
WHEN PRECIP ARRIVES IN THE WEST BY DAWN. THIS WILL BE PROBLEMATIC
WITH SFC TEMPS AND THE WINTRY PRECIP.
DESPITE THIS WINTRY EVENT...TEMPS TUESDAY WILL BE SEASOANAL WITH
40S WEST AND LOWER 50S EAST.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
AS OF 300 PM MONDAY...
STRONG COLD FRONT WILL BE WELL EAST OF THE CWA TUE NIGHT WITH STRONG
COLD AIR ADVECTION IN ITS WAKE. A FEW LINGERING MOUNTAIN SNOW
SHOWERS POSSIBLE IN MOST FAVORED UPSLOPE AREAS BUT OTHERWISE WINDY
AND COLD WITH CLEARING SKIES OVERNIGHT. H85 TEMPS FALL BACK TO -10C
TO -15C RANGE BY 12Z WED...WITH LOW TEMPS LIKELY TO BE UPPER TEENS
NW TO MID-20S EAST. 12Z NAM ALSO SHOWS NW WINDS AT H85 IN THE 50-60
KT RANGE EARLY WED MORNING WHICH MAY WARRANT A WIND
ADVISORY...ESPECIALLY ALONG EXPOSED RIDGETOPS. EITHER WAY WILL BE A
VERY CHILLY START TO THE DAY. WITH GRADIENT BETWEEN DEPARTING
SURFACE LOW OVER THE MARITIMES AND 1040 MB RIDGE OF HIGH PRESSURE
BUILDING SOUTHEAST FROM THE UPPER PLAINS WED LOOKS TO REMAINS
BREEZY...ALBEIT WINDS SLOWLY DIMINISHING. TEMPS RANGE FROM UPPER 20S
NW TO LOW 40S SE..ROUGHLY 10-12F BELOW MID TO LATE FEB. CLIMATOLOGY.
STRONG SURFACE RIDGE IS MAINTAINED ACROSS THE MID-ATLANTIC REGION
MOST OF THURSDAY AS A NEW STORM SYSTEM BECOMES ORGANIZED IN THE LEE
OF THE ROCKIES AND BEGINS TO LIFT OUT ACROSS THE MIDWEST AS A MAJOR
WINTER STORM WITH POSSIBLE SEVERE WX ACRS PARTS OF TEXAS. COLD AIR
DAMMING WILL BEGIN TO DEVELOP THURSDAY EVENING.NIGHT ALONG THE EAST
COAST FROM THE SAME SURFACE HIGH SLIDING EASTWARD. MEANWHILE FAST
WSW FLOW ALOFT BRINGS MOISTURE RAPIDLY NORTHEASTWARD AND LIKELY
OVERRUNNING THE COOL WEDGE WITH LIKELY P-TYPE FORCAST ISSUES AS
EARLY AS THURSDAY NIGHT.
.LONG TERM /FRIDAY THROUGH SUNDAY/...
AS OF 328 PM EST SUNDAY...
SURFACE HIGH PRESSURE WILL KEEP THE AREA DRY THURSDAY. OVERRUNNING
MOISTURE FROM THE SOUTH WILL BRING A CHANCE FOR A WINTRY MIX TO THE
AREA THURSDAY NIGHT INTO FRIDAY MORNING. INITIAL PRECIPITATION WILL
FALL INTO DRY AIR AND COULD BEGIN AS A BRIEF PERIOD OF SNOW AND/OR
SLEET. FOR THE MOST PART...RAIN IS EXPECTED THURSDAY NIGHT.
EVAPORATIVE COOLING COULD BRING FREEZING RAIN TO THE BLUE RIDGE AND
TO LOCATIONS NORTH OF HIGHWAY 460 EARLY FRIDAY MORNING. FORECAST
SOUNDINGS CONTINUE TO CARRY A PROFILE FOR FREEZING RAIN...BUT THEY
ARE SLIGHTLY WARMER TODAY AND TIMING WINDOW IS SHORTER. AMOUNTS OF
RAIN/FREEZING RAIN ARE ALSO TRENDING LIGHTER AS GULF COAST
REFLECTION AND CONVECTION MAY ROB OUR MOISTURE. IN KEEPING THE
FORECAST SIMPLE...THURSDAY-FRIDAY FORECAST MAY SOUND WORSE THAN THE
EVENT ITSELF. BUT THEN AGAIN...ANY ICE...NO MATTER HOW LIGHT IS
STILL DANGEROUS.
ASIDE FROM THE P-TYPE ISSUE...MODELS ARE IN GOOD AGREEMENT WITH
PRECIPITATION COMING INTO THE REGION THURSDAY NIGHT AND FRIDAY. RAIN
FALLING INTO THE SURFACE RIDGE WILL ENHANCE IT TO BECOME AN INSITU
WEDGE FRIDAY AND FRIDAY NIGHT. WITH BULK OF THE RAIN TO OUR
SOUTH...FRIDAY COULD JUST BE A LIGHT RAIN/DRIZZLE...GRAY DAY WITH
TEMPERATURES STUCK IN THE 30S. OUTSIDE THE WEDGE...TOWARD
BLUEFIELD...TEMPERATURES COULD JUMP INTO THE LOWER 50S FRIDAY
AFTERNOON.
MEANWHILE...WHILE WE ARE WEDGED IN FRIDAY...A SURFACE REFLECTION
ACROSS THE GULF STATES WILL TRACK EAST OVER THE SOUTHEAST USA FRIDAY
NIGHT AND OFF THE CAROLINA COAST SATURDAY MORNING. THIS WAVE WILL
PUSH WARMER AIR INTO THE REGION AND WITH IT MORE RAIN. WITH THE
TRACK OF THIS REFLECTION ACROSS THE SOUTHEAST...THE BETTER CHANCE
FOR RAIN FRIDAY NIGHT AND SATURDAY MORNING WILL BE ALONG AND EAST OF
THE BLUE RIDGE AND INTO THE PIEDMONT. ONCE THIS WAVE MOVES EAST OF
THE REGION...HIGH PRESSURE IS EXPECTED TO MOVE OVER THE MID
ATLANTIC. THE ECMWF BRINGS ANOTHER WAVE ACROSS THE SOUTHEAST
SATURDAY NIGHT FOR ANOTHER CHANCE OF RAIN. SINCE THE 12Z ECMWF IS
TRENDING TOWARD THE GFS...WILL ONLY HAVE A SLIGHT CHANCE FOR RAIN
SATURDAY AFTERNOON/NIGHT.
FRIDAY LOOKS TO BE THE COLDEST DAY WITH MOST OF THE AREA STUCK IN AN
INSITU WEDGE. ONCE THIS WEDGE BREAKS...TEMPERATURES WILL WARM ABOVE
NORMAL NEXT WEEKEND.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 321 PM EST MONDAY...
THE 12Z ECMWF REMAINS CONSISTENT WITH PREVIOUS RUNS WITH OVERRUNNING
MOISTURE THURSDAY NIGHT...INSITU WEDGE FRIDAY INTO SATURDAY
AND...HIGH PRESSURE SUNDAY AND MONDAY. THE 12Z GFS IS CONSISTENT
THURSDAY NIGHT INTO FRIDAY NIGHT. SATURDAY AND SATURDAY NIGHT...THE
GFS CREATES A VERY COMPLICATED WEATHER PATTERN THAT WOULD BRING
MORE RAIN TO THE AREA. SINCE THIS IS A NEW SCENARIO...I HAVE LOW
POPS IN FOR SATURDAY BUT PRIMARILY WENT WITH THE ECMWF SOLUTION FOR
THIS FORECAST PACKAGE.
SURFACE HIGH PRESSURE WILL BE OVERRUN WITH WARM MOIST AIR THURSDAY
NIGHT INTO FRIDAY. RAIN FALLING OVERNIGHT WILL ENHANCE AN INSITU
WEDGE...KEEPING MOST OF THE AREA DAMP AND CHILLY INTO FRIDAY
POSSIBLY SATURDAY. THIS RAIN WILL ALSO BE FALLING INTO A VERY DRY
AIR MASS. EVAPORATIVE COOLING ALONG EASTERN SLOPES OF THE BLUE RIDGE
AND IN SOME MOUNTAIN VALLEYS SUCH AS THE GREENBRIER...NEW RIVER AND
SOUTHERN SHENANDOAH...COULD HAVE ICE FROM FREEZING RAIN EARLY FRIDAY
MORNING. FORECAST SOUNDINGS CONTINUE TO PROFILE FREEZING RAIN BUT
LIKE YESTERDAY...ARE A LITTLE WARMER AND THE DURATION IS LIMITED TO
4AM-10AM FRIDAY. CONVECTION ACROSS THE SOUTHEASTERN USA MAY ROB SOME
OF OUR MOISTURE...LIMITING ICE ACCRETIONS TO UNDER A TENTH OF AN
INCH ALONG THE BLUE RIDGE AND A GLAZING IN MOUNTAIN VALLEYS.
FRIDAY NIGHT INTO SATURDAY...THE GULF LOW SHOULD TRACK ALONG THE
SOUTHEAST USA...THEN OFF THE CAROLINA COAST. COOL DAMP CONDITIONS
COULD LINGER INTO SATURDAY BUT WARM ENOUGH TO KEEP PRECIPITATION AS
RAIN. THIS LOW MOVES OFF THE COAST SATURDAY NIGHT....BREAKING THE
WEDGE...IF IT IS STILL IN THE REGION. HIGH PRESSURE WILL THEN KEEP
THE REGION DRY UNTIL MONDAY NIGHT WHEN THE NEXT SYSTEM TRACKS TO THE
EAST COAST.
AREAS WITHIN THE WEDGE WILL HAVE A VERY SMALL DIURNAL CURVE IN
TEMPERATURES THURSDAY NIGHT INTO SATURDAY. TEMPERATURES COULD BE
STUCK IN THE 30S IN THE WEDGE WHILE MID 40S TO LOWER 50S ARE
POSSIBLE OUTSIDE THE WEDGE. TEMPERATURES ARE EXPECTED TO WARM ABOVE
NORMAL SUNDAY AND MONDAY.
&&
.AVIATION /04Z TUESDAY THROUGH SATURDAY/...
AS OF 1130 PM EST MONDAY...
VFR CONDITIONS WILL START TO DETERIORATE OVER THE WEST AFTER
MIDNIGHT WITH LOWERING CIGS SPREADING EAST TO THE BLUE RIDGE
DURING THE EARLY MORNING HOURS AND OUT EAST BY DAYBREAK. WINDS
ALOFT WILL ALSO BE ON THE INCREASE PROMPTING LLWS JUST OFF THE
DECK AT ALL LOCATIONS EXCEPT KBLF WHERE MIXING TO THE SURFACE WILL
PRECLUDE MENTION...BUT ALLOW FOR GUSTY SURFACE WINDS TO 30-35 KTS
AND PERHAPS EVEN STRONGER IMMEDIATELY AHEAD OF THE APPROACHING
PRECIP LATE. DEEPER MOISTURE SHOULD INCREASE QUICKLY AS THE FRONT
APPROACHES AND WILL SEE SOME PRECIP DEVELOP IN THE EARLY MORNING
HOURS FROM WEST TO EAST. PTYPE WILL BE A BIT PROBLEMATIC AS MODEL
SOUNDINGS INDICATE MOSTLY SNOW AT THE ONSET FOR KLWB... RAIN FOR
KDAN...AND A WINTRY MIX FOR SITES IN BETWEEN. APPEARS CIGS MAY
STAY VFR UNTIL ABOUT AN HOUR OR TWO BEFORE THE FAST MOVING AXIS OF
PRECIP ARRIVES...THEN QUICKLY LOWER INTO MVFR/OCNL IFR LEVELS WEST
OF THE BLUE RIDGE BEFORE DAWN...AND OUT EAST AROUND 12Z/7AM. LOOKS
LIKE MOST SPOTS WILL WARM ENOUGH TO CAUSE A CHANGE TO JUST -RA BY
MID MORNING EXCEPT VALLEYS WHERE TRAPPED COLD AIR COULD MAKE FOR
SOME LINGERING LIGHT MIX A WHILE LONGER. THIS BASED ON A SCENARIO
WHERE THE PRECIP IS AS MUCH AS 2 TO 3 HOURS FASTER THAN THE
FASTEST MODEL SOLUTION GIVEN TENDENCY OF THESE EVENTS TO ROCKET
EAST MUCH FASTER THAN PROGGED UNDER THE NOSE OF THE JET ALOFT.
VERY STRONG SOUTH/SW JET WILL REMAIN IN PLACE TUESDAY MORNING BUT
WILL BE LIMITED IN MIXING DOWN WITHIN PRECIP AS WILL SEE QUITE A
GRADIENT WITHIN THE LOWEST FEW THOUSAND FEET AS THE 85H 50-60 KT
JET SHIFTS EAST. THUS WILL KEEP LLWS MENTION IN AT MOST LOCATIONS
OUTSIDE OF KBLF UNTIL THINGS START TO MIX OUT BY LATE MORNING AND
ESPCLY DURING THE AFTERNOON WHEN TRAJECTORIES TURN MORE WESTERLY
AND STRONGER GUSTS OF 25-30+ KTS REACH THE SURFACE. OTRW THINK SIG
PRECIP WILL END BY 20Z/3PM MOST SPOTS WITH ONLY SOME LINGERING -RA
OR SHOWERS ACROSS THE NW INTO EARLY TUESDAY EVENING.
.EXTENDED AVIATION DISCUSSION...
GUSTY WINDS WILL CONTINUE BEHIND THE FRONT TUESDAY NIGHT INTO
WEDNESDAY...WITH ENOUGH SYNOPTIC MOISTURE LINGERING TO KEEP
CLOUDS AROUND FOR KLWB AND LIKELY KBLF AS WELL. HIGH PRESSURE WILL
THEN BUILD IN THURSDAY ALLOWING FOR VFR WEATHER. ANOTHER FRONTAL
SYSTEM WITH THE NEXT ROUND OF PRECIP WILL ARRIVE THURSDAY NIGHT
AND FRIDAY WITH MORE MVFR/IFR CONDITIONS POSSIBLE. THIS MAY BE
FOLLOWED BY ANOTHER IMPULSE HEADING NE FROM THE GULF COAST AREA
ALONG THE RESIDUAL FRONT ON SATURDAY WHICH MAY LINGER LOW FLYING
CONDITIONS INTO SATURDAY NIGHT.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...WINTER WEATHER ADVISORY FROM 3 AM TO 10 AM EST TUESDAY FOR
VAZ007-009>020-022>024.
NC...WINTER WEATHER ADVISORY FROM 3 AM TO 10 AM EST TUESDAY FOR
NCZ001-002-018.
WV...WINTER WEATHER ADVISORY FROM 3 AM TO 10 AM EST TUESDAY FOR
WVZ042>045.
&&
$$
SYNOPSIS...WP
NEAR TERM...JH/WP
SHORT TERM...PC
LONG TERM...RCS
AVIATION...JH/MBS/RAB
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
526 PM CST WED FEB 20 2013
.SHORT TERM...TONIGHT THROUGH SATURDAY
232 PM CST WED FEB 20 2013
FORECAST CONCERNS ARE ON WINTER STORM IMPACTING THE AREA THURSDAY
NIGHT INTO FRIDAY.
LATEST WATER VAPOR IMAGERY AND 500 MB RAP ANALYSIS SHOWED A COMPLEX
PATTERN ACROSS THE CONUS TODAY. AN UPPER LOW WAS LOCATED OVER NEW
ENGLAND WHILE ANOTHER WAS MOVING INTO SOUTHERN CALIFORNIA. AN UPPER
RIDGE EXTENDED FROM THE MID MISSISSIPPI RIVER VALLEY NORTH THROUGH
THE UPPER MIDWEST.
THE UPPER LOW OVER SOUTHERN CALIFORNIA WILL BE THE MAIN FEATURE TO
WATCH CLOSELY TONIGHT AS IT MOVES THROUGH ARIZONA AND NEW MEXICO
OVERNIGHT...EJECTING INTO THE CENTRAL PLAINS ON THURSDAY. THE LOW
WILL LIFT NORTHEAST THROUGH SOUTHEAST NEBRASKA EARLY FRIDAY EVENING.
AHEAD OF THE APPROACHING LOW...STRONG ISENTROPIC LIFT WILL MOVE
MOVE INTO THE FORECAST AREA ON THE 280-310 K SURFACES DURING THE
EVENING HOURS ON THURSDAY LEADING TO THE DEVELOPMENT OF SNOW.
IMPRESSIVE LIFT NOTED IN THE DENDRITIC GROWTH ZONE THURSDAY
EVENING INTO LATE THURSDAY NIGHT...WITH LIFT OF -20 UBAR/S NOTED
AT -15C. THE ONLY NEGATIVE WITH THIS SYSTEM IS THAT THE
INGREDIENTS FOR HEAVY SNOW FALL ADVECT NORTHEAST THROUGH THE
FORECAST AREA VERY QUICKLY DURING THE OVERNIGHT HOURS.
HOWEVER...MOST ARES WILL SEE A PERIOD OF HEAVY SNOWFALL WITH
ACCUMULATION RATES OF 1 TO 1.5 INCHES PER HOUR. SNOW ACCUMULATIONS
BY 12Z FRIDAY ARE EXPECTED TO RANGE FROM 5 TO 7 INCHES ACROSS MUCH
OF NORTHEAST IOWA. LOCATIONS OVER SOUTHEAST MINNESOTA AND
SOUTHWEST THROUGH CENTRAL WISCONSIN ARE EXPECTED TO SEE SNOW
ACCUMULATIONS OF 3 TO 6 INCHES. THE BULK OF THE SNOW WILL FALL
DURING THE OVERNIGHT HOURS THROUGH THE FRIDAY MORNING
COMMUTE...LEADING TO TRAVEL IMPACTS. HAVE ISSUED A WINTER STORM
WARNING FOR MOST OF NORTHEAST IOWA...EXCLUDING ALLAMAKEE
COUNTY...AND HAVE ISSUED A WINTER WEATHER ADVISORY FOR THE REST OF
THE FORECAST AREA. SEE WATCH/WARNING/ADVISORIES SECTIONS BELOW FOR
SPECIFIC TIMING. SNOWFALL AMOUNTS HAVE TRENDED SLIGHTLY LESS IN
THE 12Z GUIDANCE AND THIS MAKES SENSE GIVEN THE PROGRESSIVE NATURE
OF THE HEAVY SNOWFALL INGREDIENTS. THE LOW WILL LIFT NORTHEAST
DURING THE DAY ON FRIDAY AND IS EXPECTED TO BE LOCATED OVER SOUTH
CENTRAL MINNESOTA BY MIDDAY FRIDAY. LIGHT SNOW LOOKS TO PERSIST
INTO FRIDAY AFTERNOON WITH ADDITIONAL ACCUMULATIONS OF 1 TO 2
INCHES POSSIBLE. THE SNOW WILL TAPER OFF SOUTH AND WEST OF
INTERSTATE 94 THROUGH THE AFTERNOON HOURS AND PERSIST NORTH OF
I-94 INTO FRIDAY EVENING. WILL HAVE TO KEEP A CLOSE EYE ON
FREEZING DRIZZLE POTENTIAL OVER SOUTHWEST INTO CENTRAL WISCONSIN
AS ICE IS LOST ALOFT LATE FRIDAY MORNING INTO EARLY FRIDAY
AFTERNOON. OTHERWISE...HIGH PRESSURE WILL BE IN CONTROL TONIGHT
INTO THURSDAY MORNING PROVIDING COOL AND QUIET CONDITIONS. HIGH
CLOUDS WILL BE ON THE INCREASE FROM THE SOUTHWEST AHEAD OF THE
APPROACHING SYSTEM. LOOK FOR LOWS TONIGHT TO RANGE FROM THE SINGLE
DIGITS BELOW ZERO ACROSS NORTH CENTRAL WISCONSIN TO THE SINGLE
DIGITS ABOVE ZERO OVER NORTHEAST IOWA.
THE LOW WILL LIFT INTO UPPER MICHIGAN EARLY ON SATURDAY AS WEAK HIGH
PRESSURE BUILDS INTO THE FORECAST AREA. MOSTLY CLOUDY SKIES ARE
EXPECTED ACROSS THE FORECAST AREA ON SATURDAY UNDER THE INFLUENCE OF
WEAK CYCLONIC FLOW IN THE WAKE OF THE DEPARTING LOW. LIGHT SNOW
COULD LINGER ACROSS NORTH CENTRAL WISCONSIN DURING THE DAY. HIGHS ON
SATURDAY WILL RANGE FROM THE MID 20S OVER CENTRAL WISCONSIN TO THE
LOWER 20S OVER SOUTHEAST MINNESOTA. A VIGOROUS TROUGH WILL MOVE
THROUGH THE PACIFIC NORTHWEST ON SATURDAY...DIVING INTO THE CENTRAL
ROCKIES SATURDAY NIGHT. THIS SYSTEM IS THE NEXT FEATURE TO KEEP A
CLOSE EYE ON.
.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY
232 PM CST WED FEB 20 2013
20.12 MEDIUM RANGE MODELS ARE IN REASONABLE SATURDAY NIGHT THROUGH
SUNDAY SHOWING THE TROUGH PUSHING INTO THE CENTRAL ROCKIES BY SUNDAY
AFTERNOON. MEANWHILE...RIDGING WILL BUILD OVER THE UPPER MISSISSIPPI
RIVER VALLEY PROVIDING PARTLY SUNNY SKIES ON SUNDAY. HIGHS ON SUNDAY
ARE EXPECTED TO RANGE FROM THE LOWER 30S OVER CENTRAL WISCONSIN TO
THE UPPER 20S OVER NORTHEAST IOWA. THE TROUGH IS EXPECTED TO MOVE
EAST OUT OF THE ROCKIES AND INTO THE CENTRAL PLAINS AND DEEPENING
INTO A STRONG UPPER LOW. MODEL SOLUTIONS START TO DIVERGE SLIGHTLY
MONDAY INTO TUESDAY. THE 20.00 ECMWF TAKES THE LOW ACROSS EASTERN
KANSAS THROUGH NORTHERN MISSOURI MONDAY NIGHT AND INTO NORTHERN
ILLINOIS BY EARLY TUESDAY MORNING. THE GFS HAS A SLIGHTLY MORE
NORTHERLY TRACK. THIS SYSTEM WILL BRING WARMER AIR WITH IT AND THE
POTENTIAL FOR A RAIN AND SNOW MIX. THIS SYSTEM HAS THE POTENTIAL
TO BRING SIGNIFICANT SNOWFALL TO THE REGION BUT THE EXACT TRACK IS
UNCERTAIN AND WILL BE PINNED DOWN OVER THE NEXT FEW MODEL RUNS.
THE 20.00 ECMWF LIFTS THE LOW NORTH INTO EASTERN UPPER MICHIGAN BY
WEDNESDAY MORNING WHILE THE GFS TAKES IT TO THE EAST INTO THE OHIO
RIVER VALLEY. LIGHT SNOW CHANCES WILL CONTINUE TUESDAY INTO
WEDNESDAY...DEPENDING ON THE LOW TRACK.
&&
.AVIATION...TONIGHT AND THURSDAY
526 PM CST WED FEB 20 2013
VFR CONDITIONS EXPECTED THROUGH THIS TAF PERIOD WITH SCATTERED
HIGH CLOUDS OVERNIGHT AND THICKENING AFTER 18Z THURSDAY. EXPECT
WINDS TO BE LIGHT AND LESS THAN 10 KNOTS WITH A GRADUAL SWITCH TO
A MORE NORTHEASTERLY DIRECTION TONIGHT AND THEN EASTERLY THURSDAY AFTERNOON.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
232 PM CST WED FEB 20 2013
WI...WINTER WEATHER ADVISORY FROM 6 PM THURSDAY TO 6 PM CST FRIDAY
FOR WIZ041-053>055-061.
WINTER WEATHER ADVISORY FROM MIDNIGHT THURSDAY NIGHT TO 6 PM CST
FRIDAY FOR WIZ017-029-032>034-042>044.
MN...WINTER WEATHER ADVISORY FROM 6 PM THURSDAY TO 6 PM CST FRIDAY
FOR MNZ079-086>088-094>096.
IA...WINTER STORM WARNING FROM 6 PM THURSDAY TO 6 PM CST FRIDAY FOR
IAZ008>010-018-019-029-030.
WINTER WEATHER ADVISORY FROM 6 PM THURSDAY TO 6 PM CST FRIDAY
FOR IAZ011.
&&
$$
SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION...RABERDING
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1126 PM CST MON FEB 18 2013
.SHORT TERM...TONIGHT
635 PM CST MON FEB 18 2013
A FEW ISSUES TO DEAL WITH AS DESCRIBED BELOW.
1. TEMPERATURES HAVE BEEN FALLING A LITTLE QUICKER THAN PREVIOUSLY
EXPECTED...WITH THE STRONG NORTHWEST WINDS DRIVING IN ARCTIC AIR
FASTER FROM THE DAKOTAS. ADJUSTED THE HOURLY TEMPERATURE TREND A
FEW TIMES TO ACCOUNT FOR THIS. SO FAR...LOW TEMPERATURES STILL
SEEM ON TRACK.
2. COMBINATION OF THE RECENT SNOW MELTING ON WARM ROADWAYS...ALONG
WITH THE ARCTIC AIR FLOWING IN AND SUN GOING DOWN ALLOWING ROADWAY
TEMPERATURES TO FALL BELOW FREEZING...HAS CAUSED ICY SPOTS TO
FORM. HAVE BEEN HANDLING THIS WITH SPECIAL WEATHER STATEMENTS.
3. RAP DERIVED WIND GUSTS SHOW VALUES OF 35-39 KTS BETWEEN 05-15Z
ACROSS MUCH OF THE FORECAST AREA...ABOUT 5 KNOTS STRONGER THAN
WHAT MOMENTUM TRANSFER WOULD SUGGEST ON RAP FORECAST SOUNDINGS. IF
THE DERIVED VALUES WERE CORRECT...WE NEED A WIND ADVISORY.
THE IDEA OF GUSTS INCREASING SEEM REASONABLE...AS DURING THE
AFOREMENTIONED TIME PERIOD WE ARE EXPERIENCING THE TROPOPAUSE DROP
OVER 100 MB...DUE TO THE UPPER TROUGH AXIS OVER WESTERN MINNESOTA
MOVING IN. IN ADDITION...DURING THIS TIME PERIOD IS WHEN THE REAL
ARCTIC AIR SURGE TAKES PLACE WITH 925MB TEMPS DROPPING NEARLY 10C.
HOWEVER...IN THE PAST THE RAP DERIVED WIND GUSTS HAVE HAD A LITTLE
HIGH BIAS. THUS...HAVE TAKEN A COMPROMISE APPROACH AND BROUGHT
WIND GUSTS UP A COUPLE KNOTS...STILL BELOW A WIND ADVISORY.
4. LATEST HRRR MODEL RUNS OF COMPOSITE REFLECTIVITY HAS SHOWN AN
ENHANCEMENT OF RETURNS DURING THE 06-12Z PERIOD ACROSS MUCH OF
WISCONSIN. RAP FORECAST SOUNDINGS DURING THE SAME TIME SHOW THAT
THE DEPTH OF THE CLOUD GROWS FROM ABOUT 4000 FT TO 8000 FT...AND
NEARLY ALL THE CLOUD IS IN THE DENDRITIC GROWTH ZONE. NOW THE LIFT
IS NOT ALL THAT IMPRESSIVE...BUT THERE IS WEAK LIFT THROUGHOUT
MUCH OF THE CLOUD DEPTH. IT APPEARS THE LIFT OCCURS WITH THE
TROPOPAUSE DROP ACCOMPANYING THE UPPER TROUGH AXIS...ALONG WITH
THE ASSOCIATED 500-300MB PV ADVECTION. GIVEN THE STEEP LOW LEVEL
LAPSE RATES IN PLACE AS WELL WITH THE COLD ADVECTION...FIGURE IT
WARRANTS RAISING PRECIPITATION CHANCES TO AT LEAST 60 ACROSS MUCH
OF WISCONSIN BETWEEN 06-12Z. STILL...THERE MAY ONLY BE A FEW
TENTHS OF HARD TO MEASURE SNOW DUE TO ALL THE WIND.
.LONG TERM...THURSDAY NIGHT THROUGH MONDAY
314 PM CST MON FEB 18 2013
THE MAIN SNOW BAND WILL LIFT NORTH THROUGH THE REGION ON THURSDAY
NIGHT AS THE MAIN MID LEVEL TROUGH SWINGS NORTHWARD. THIS WILL
YIELD A BRIEF PERIOD OF MODERATE SNOW THAT WILL LIKELY BE
WEAKENING AS IT TRACKS TO THE NORTHEAST. QPF AMOUNTS APPEAR TO
RANGE FROM AROUND 0.35 INCHES IN NORTHEAST IOWA TO AROUND 0.15
INCHES IN NORTH CENTRAL WISCONSIN BY THE TIME THE SYSTEM ENDS ON
FRIDAY. WITH SNOW RATIOS EXPECTED TO BE IN THE 10/15:1 RANGE...IT
LOOKS LIKE THE HIGHEST SNOW ACCUMULATIONS SHOULD BE ACROSS
NORTHEAST IOWA AND PORTIONS OF SOUTHEAST MINNESOTA AND FAR
SOUTHWEST WISCONSIN WHERE 3-5 INCHES COULD FALL. SNOW AMOUNTS ARE
EXPECTED TO DECREASE TO THE NORTHEAST WITH A 2-4 INCH RANGE
EXPECTED INTO NORTH CENTRAL WISCONSIN.
LIGHT SNOW WILL COME TO AN END FROM SOUTH TO NORTH FRIDAY NIGHT
INTO SATURDAY WITH A BRIEF RIDGE OF HIGH PRESSURE EXPECTED TO MOVE
ACROSS THE REGION NEXT WEEKEND. ANOTHER SYSTEM IS THEN FORECAST TO
OCCUR SOMETIME BETWEEN SUNDAY AND TUESDAY WITH THE 19.12Z
GFS/ECMWF/FIM MODELS ARE SHOWING DIFFERENT TIMING IN REGARD TO
WHEN THE LOW PASSES THROUGH. THE 19.12Z GFS IS THE FASTEST WITH
HAVING THE LOW COME THROUGH ON SUNDAY WHILE THE 19.12Z ECMWF IS
THE SLOWEST WITH HAVING IT COME THROUGH ON MONDAY. THE 19.12Z FIM
SEEMS TO BE A BLEND IN BETWEEN THE TWO AND MAY BE A GOOD
COMPROMISE. THE TRACK THOUGH SEEMS TO BE SIMILAR WITH TAKING THE
CENTER OF THIS LOW OFF TO THE WEST OF THE REGION...WHICH PROBABLY
LEAVES US MORE INTO A MIXED P-TYPE.
&&
.AVIATION...THROUGH 06Z WEDNESDAY
1126 PM CST MON FEB 18 2013
CYCLONIC FLOW OF MOISTURE AROUND DEEPENING LOW PRESSURE LIFTING
FROM LAKE MICHIGAN INTO EASTERN ONTARIO WILL MAINTAIN AN MVFR
STRATUS DECK AT BOTH TAF SITES THROUGH 06Z WEDNESDAY. AS WE
APPROACH 06Z...THOUGH...DRIER AIR COMING OUT OF ARCTIC HIGH
PRESSURE DROPPING DOWN INTO MINNESOTA MAY BEGIN TO CLEAR THE
CLOUDS OUT. THE COMBINATION OF THE MVFR STRATUS DECK SITUATED
MOSTLY IN THE DENDRITIC GROWTH ZONE...ALONG WITH SERIES OF TROUGHS
MOVING THROUGH DURING THE MORNING HOURS TO PROVIDE LIFT...WILL
RESULT IN PERIODS OF IFR TO VFR SNOW/SNOW SHOWERS. THE LOWEST
VISIBILITIES ARE EXPECTED PRIOR TO 12Z WHEN THE STRONGEST TROUGH
MOVES THROUGH...WHICH HAS ALREADY PRODUCED IFR VISIBILITIES AT
KRST. LOOK FOR THE FLURRIES TO COME TO END FOR THE AFTERNOON AS
THE DEPTH OF THE CLOUD DECREASES.
ALONG WITH THE SNOW AND STRATUS...WINDS ARE GOING TO BE AN ISSUE
TOO. NORTHWEST WINDS AT BOTH TAF SITES SHOULD HOLD STEADY BETWEEN
15 AND 20 KT WITH GUSTS OF 25 AND 30 KT THROUGH THE DAY
TODAY...AIDED BY COLD AIR FLOWING IN...A TIGHT PRESSURE GRADIENT
AND DAYTIME MIXING. EXPECT THE GUSTS TO DIMINISH AND WINDS TO
DECREASE SLIGHTLY BY LATE TUESDAY EVENING WITH THE PRESSURE
GRADIENT BEGINNING TO RELAX.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
314 PM CST MON FEB 18 2013
WI...NONE.
MN...WIND CHILL ADVISORY FROM 3 AM TO NOON CST TUESDAY FOR MNZ086-087-
094-095.
IA...WIND CHILL ADVISORY FROM 3 AM TO NOON CST TUESDAY FOR IAZ008-009-
018-019.
&&
$$
SHORT TERM...AJ
LONG TERM...HALBACH
AVIATION...AJ
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
1016 PM CST MON FEB 18 2013
.UPDATE...CYCLOGENESIS EXPECTED TO INTENSIFY FROM NOW THROUGH 12Z
TUE WITH A 987 MB LOW EXPECTED OVER FAR ERN UPPER MI AT THAT TIME.
DRY SLOT IS ENDING THE SNOW FROM WEST TO EAST WITH SOME
DISSIPATION FROM THE SOUTH AS WELL. THIS WILL LIMIT SNOW ACCUMS
OVER FAR SE WI. HOWEVER...UPPER TROUGH TO THE EAST WILL AMPLIFY
VIA CYCLOGENESIS AND BECOME A CLOSED UPPER LOW OVER WI LATER TNT.
THUS SNOW WILL REDEVELOP FROM THE NORTH AND WEST AS SHOWN BY RADAR
TRENDS FROM SRN MN INTO CENTRAL WI. EXPECT SOME ADDITIONAL...MINOR
SNOW ACCUM LATER TNT INTO TUE AM. FALLING TEMPS AND WINDY
CONDITIONS LOOK ON TRACK FOR THE OVERNIGHT AND TUE AM WITH VERY
COLD TEMPS AND WIND CHILLS EXPECTED. WINDS WILL APPROACH WIND
ADVISORY CRITERIA FOR TUE ESPECIALLY OVER EAST CENTRAL WI.
&&
.AVIATION/06Z TAFS/...PERIODS OF LIGHT SNOW WILL CONTINUE THROUGH
TUE AM AND DIMINISH BY TUE AFTERNOON. VSBYS WILL RANGE FROM 1-3
MILES IN SE WI THROUGH 07Z AND THEN RANGE FROM 3-6 MILES THE
REMAINDER OF THE NIGHT AND THROUGH TUE AM OVER ALL OF SRN WI. IFR
CIGS WILL TRANSITION TO MVFR CIGS THROUGHOUT TUE AM AS MUCH
COLDER AIR ON BRISK WEST TO NORTHWEST WINDS ARRIVES. MVFR CIGS
WILL BECOME SCT CLOUD COVER TUE EVENING AS DRY ARCTIC AIR
CONTINUES TO MOVE INTO THE REGION.
&&
.PREV DISCUSSION... /ISSUED 237 PM CST MON FEB 18 2013/
SHORT TERM...
TONIGHT - CONFIDENCE...MEDIUM
STRONG COLD FRONT EXITS TO THE EAST OF WI THIS EVENING. HRRR MODEL
HAS GOOD HANDLE ON PRECIP TRENDS AND FOLLOWED ON POP GRIDS.
WEST/EAST TREND IN CHANGEOVER OF PRECIP TYPE AS COLDER TEMPS DRIVE
IN. UPPER TROUGH AXIS SHIFTS EAST FROM THE PLAINS. QUICK HITTING DEF
ZONE BAND OF PRECIP HAS SOME PUNCH TO IT BACK IN CNTRL/ERN IA. DECENT
UPPER JET DIVERGENCE WITH THE NEWD MOVG UPPER WAVE FROM SRN IA WILL
KEEP PRECIP GOING WELL INTO THE EVENING WITH POTENTIAL FOR LIGHT
SNOW ACCUMS...MOSTLY 0.5 - 1.0...THOUGH BULK OF PRECIP EXPECTED WHEN
LIQUID SUPPORTING PROFILE IN PLACE. SEEING SOME MINUS TEENS AT 925
IN WESTERN CWA LATER TONIGHT WITH GUSTY NW WINDS AFTER FROPA.
TUESDAY - CONFIDENCE...MEDIUM
CONTINUED COLD AIR ADVECTION IN WAKE OF THE LOW. GUSTY NW WINDS
COMBINED WITH THE MUCH COLDER AIRMASS WILL MAKE FOR SOME RATHER
CHILLY WIND CHILLS...ESPECIALLY EARLY. 925 TEMPS -15 TO -19C ALL
DAY. HIGHS WILL NOT MAKE IT OUT OF THE TEENS. WILL GET GUSTS INTO
THE 30-40 MPH RANGE GIVEN DECENT GRADIENT/MIXED ENVIRONMENT TAPPING
INTO SOME OF THE STRONGER WINDS AT 900-925 MILLIBARS. WILL KEEP SOME
CHANCE POPS IN THE EASTERN CWA AS CYCLONIC FLOW KEEPS SHSN POTENTIAL
IN PLACE. WENT WITH A BLEND OF ECMWF/NAM QPF AS GFS LOOKS TOO
GENEROUS WITH QPF.
TUESDAY NIGHT AND WEDNESDAY...FORECAST CONFIDENCE...HIGH
THE MID/UPPER LEVEL TROUGH OVER THE EASTERN GREAT LAKES AND
SOUTHEAST CANADA MOVES OFF AS AN UPPER LEVEL RIDGE MOVES INTO THE
UPPER MISSISSIPPI VALLEY WEDNESDAY. STILL A COLD CYCLONIC FLOW AT
700 MB TUESDAY NIGHT AND WEDNESDAY. THE BRISK NORTHWEST WINDS
TUESDAY NIGHT DIMINISH AS SURFACE HIGH PRESSURE REACHES WISCONSIN
WEDNESDAY AFTERNOON.
THURSDAY AND FRIDAY...FORECAST CONFIDENCE...MEDIUM
THE STRONG SHORTWAVE EXITS THE SOUTHERN ROCKIES AND REACHES THE
WESTERN KANSAS REGION THURSDAY MORNING. THE 12Z GFS/GEM/NAM TAKE
THE UPPER LOW INTO EASTERN NEBRASKA/WESTERN IOWA AREA EARLY THURSDAY
EVENING...AS IT SLOWLY FILLS/WEAKENS. THE UPPER LOW REMAINS IN THE
DAKOTA/WESTERN MINNESOTA BORDER AREA LATE THURSDAY NIGHT AND FRIDAY...
ALONG WITH THE SLOW WEAKENING TREND.
THE NAM SHOWS UPPER LEVEL DIVERGENCE SPREADING ACROSS SOUTHERN
WISCONSIN THURSDAY. THE RATHER STRONG 700 UPWARD MOTION OVER IOWA
REACHES NORTHERN ILLINOIS...EASTERN IOWA AND SOUTHEAST MINNESOTA
THURSDAY AFTERNOON...BUT REMAINS WEAK OVER SOUTH CENTRAL AND
SOUTHEAST WISCONSIN INTO THE EARLY EVENING. THE HIGH 700 MB RH
ENTERS AREAS SOUTHWEST OF MADISON BY 6 PM. THE NAM FORECAST
SOUNDINGS SHOW VERY DRY AIR BELOW 10 THSD FT. HOWEVER THE RATHER
STRONG UPWARD MOTION TOWARDS DUBUQUE DOES SATURATE THE AIR MASS IN
THE FAR SOUTHWEST TOWARD EVENING. THE 12Z GFS IS SOMEWHAT FASTER
BRINGING 700 MB SATURATION FROM NEAR LONE ROCK TO
JANESVILLE...ALTHOUGH THE 850 MB SATURATION IS STILL OVER FAR
SOUTHWEST WISCONSIN. THEREFORE MUCH OF THE FORECAST AREA MAY
REMAIN DRY.
NEXT PROBLEM IS THAT THE STRONGEST 700 MB UPWARD MOTION IS IN A
FAIRLY NARROW BAND THAT PUSHES QUICKLY NORTHEAST THURSDAY NIGHT AS
THE 850 LOW LEVEL JET WEAKENS.
THE 12Z GFS GIVES 24 HOUR PRECIPITATION VALUES ONLY AROUND 0.20 INCH.
THE 00Z ECMWF IS SIMILAR WHILE THE 12Z GEM IS A JUST A LITTLE
HIGHER. SNOW RATIOS AVERAGE BETWEEN 10 AND 15 TO 1. THIS WOULD
INDICATE AROUND A 2 TO POSSIBLY 3 INCH SNOW TOTAL. EVENT CONSENSUS
PRECIPITATION IS AROUND 0.30.
LONG TERM...
+
SATURDAY...FORECAST CONFIDENCE...MEDIUM TO HIGH
THE MID LEVEL TROUGH CONTINUES TO SHEAR OUT FROM WEST TO EAST AND
LIFT TOWARD THE UPPER GREAT LAKES AS THE MID LEVEL AND SURFACE
TROUGH LIFTS INTO NORTHERN WISCONSIN BY EARLY SATURDAY MORNING.
THEREFORE MAINLY LIGHT SNOW OR FLURRIES ARE EXPECTED ACROSS THE
SOUTH FRIDAY NIGHT.
SUNDAY AND MONDAY...FORECAST CONFIDENCE...LOW TO MEDIUM
THE MODELS BEGIN A SOUTHWEST MID/UPPER FLOW AHEAD OF ANOTHER
TROUGH OVER THE SOUTHERN/CENTRAL ROCKIES ON THE 00Z ECMWF BUT
FARTHER NORTH ON THE 12Z GFS. THIS SHORTWAVE REACHES THE NORTHERN
AND CENTRAL PLAINS SUNDAY ON THE GFS...BUT REMAINS OVER THE
ROCKIES AS IT DIGS SOUTH ON THE 00Z ECMWF.
BY MONDAY THIS SHORTWAVE PUSHES THROUGH WISCONSIN ON THE 12Z GFS
BUT ONLY REACHES THE EASTERN KANSAS/WESTERN MISSOURI AREA MONDAY.
A WEAK SURFACE LOW REACHES THE WESTERN LAKE SUPERIOR AREA MONDAY
MORNING...WHILE A STRONG LOW REMAINS OVER OKLAHOMA ON THE 00Z
ECMWF. GIVEN THE LARGE DISCREPANCY CONFIDENCE IS LOW...BUT WOULD
TREND TOWARD THE 00Z ECMWF BASED ON BOTH MODELS PRIOR MODEL RUNS.
AVIATION/00Z TAFS/...
MID/HIGH LEVEL CLOUDS TO GIVE WAY TO MORE
WIDESPREAD MVFR CEILINGS AS MOISTURE INCREASES AND CEILINGS LOWER
WITH ARRIVAL OF PRECIP. EXPECTING PRECIP TO OVERSPREAD THE AREA
BETWEEN 21-00Z TIME FRAME AS RAIN. WINDOW OF IFR CEILINGS THIS
EVENING IN THE STEADY PRECIP AREAS. AS COLD FRONT MOVES IN LATER
THIS AFTERNOON/EVENING...THE TRANSITION TO LIGHT SNOW WILL SPREAD
WEST TO EAST. QUITE BLUSTERY TUESDAY WITH GUSTY NW WINDS AND SHSN
POTENTIAL INTO AT LEAST MIDDAY. MVFR CEILINGS WILL PERSIST IN THE
CYCLONIC FLOW.
MARINE...
A SMALL CRAFT ADVISORY IS IN EFFECT THROUGH 6 AM TUESDAY
WITH A GALE WARNING GOING INTO EFFECT FROM 6AM TUE THROUGH 6 PM
TUESDAY. A SMALL CRAFT ADVISORY WILL THEN BE NEEDED AT THAT POINT
THROUGH WEDNESDAY MORNING. THESE CONDITIONS ARE DUE TO THE
APPROACH...THEN PASSAGE OF A STRONG LOW PRESSURE SYSTEM AND COLD
FRONT TODAY AND THIS EVENING. STRONG SOUTH WINDS WILL PRECEDE THE
LOW...FOLLOWED BY WINDS VEERING TO THE WEST BEHIND THE FRONT AND
INCREASING TO GALE FORCE BY TUESDAY MORNING.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR LMZ643>646.
GALE WARNING UNTIL 6 PM CST TUESDAY FOR LMZ643>646.
&&
$$
UPDATE...GEHRING
TONIGHT/TUESDAY AND AVIATION/MARINE...COLLAR
TUESDAY NIGHT THROUGH MONDAY...HENTZ
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1232 AM EST THU FEB 21 2013
...Updated Aviation Discussion...
.Short Term (Tonight through Thursday Night)...
Issued at 300 PM EST Wed Feb 20 2013
...A Brief Period of Wintry Weather Coming North of the I-64
Corridor...
What a mess as far as dealing with winter weather, as our next
system will bring it`s winter weather transition zone right across
our forecast area Thursday afternoon to late Thursday night.
Until then, the main forecast issue tonight will be cloud cover.
Shield of mid/high clouds moving in now is not forecast to last all
night. The RAP is advertising additional lower level clouds moving
in from the north, a low stratus, which right now is associated with
the flow coming off Lake Michigan. Will lean toward the rest of the
guidance, which keeps us clearer, overnight, except over the far
north. Then mid clouds should increase again as the system mentioned
above starts to influence our weather.
The atmosphere will saturate from above as an occluded front
approaches from the west. Deep isentropic ascent ahead of this front
will allow precipitation to start west of the I-65 corridor by late
afternoon. With the onset of this precip, expect temperatures to
drop a couple of degrees, which will allow for a mix of sleet/snow
across the north and cold rain down south. By 00Z, warm air aloft
will help to melt the deep freezing layer, allowing for the chance
for freezing rain across the north. As the night goes on, the warm
air will deepen and expect a transition over the just rain areawide
by around 09Z.
Forecast uncertainty remains high enough to keep us from issuing an
advisory. Went under guidance for temperatures at the surface and
aloft. If model forecast temperatures are true, and it should be
noted that our forecast errors for this forecast time period average
2-3 degrees, than much more of the area will be mostly rain. Based
on this uncertainty, have decided to issue just a special weather
statement on the chance for winter weather and hold off on issuing a
third-period advisory.
.Long Term (Friday through Tuesday Night)...
Issued at 326 PM EST Wed Feb 20 2013
The beginning of the long term period will feature a strong
shortwave pushing north through the Northern Plains. In its wake, a
trough will amplify across the central CONUS this weekend which will
work into the Ohio Valley. Another upper ridge will amplify across
the Ohio Valley ahead of the next system set to affect the region
early next week.
A warm front will be lifting north through the region early Friday
morning, with the associated synoptic forcing/isentropic ascent
lifting north into Ohio. Therefore, precipitation will taper off
from southwest to northeast through the day as a dry slot works
into the region. Temperatures on Friday will be rather warm, as the
surface cold front will remain well off to the west, allowing for
southwesterly winds to aid in a quick warmup in the wake of the
morning precipitation.
The associated cold front will finally push through the region late
Friday into early Saturday. Another shortwave will swing through
the mean trough Saturday morning, which will induce secondary
surface low development across TN/GA. As this wave rides along the
departing cold front, it will act to stall its progress. In fact,
the 12Z suite of guidance is suggesting there may be enough moisture
kicked back into the region to produce some additional precipitation
across the Cumberland area as the shortwave and surface low pass
by. If this moisture were to get far enough north into the cooler
air, then some light freezing rain/drizzle could creep into the
northern Bluegrass region Saturday morning. However, this
probability looks rather low at this point and will leave
precipitation as all rain for now and confined to the far
east/southeast portions of the CWA.
A ridge will build across the region late Saturday through Monday,
providing calm and dry weather conditions. Temperatures will warm
each day through the weekend, as temperatures in the lower 40s on
Saturday warm into the middle 50s by Monday.
Another strong upper level wave will eject out into the Central and
Northern Plains on Monday. This system looks very similar to the
Thursday/Friday system, spreading a slug of precipitation north in
association with a wave of isentropic ascent atop the surface warm
front. This time, however, the cooler air will not be in place
ahead of the approaching warm front, so any and all precipitation
will remain rain. The surface cold front will push through late
Monday night into Tuesday morning, dropping temperatures back into
the upper 40s Tuesday afternoon.
The 20/12Z GFS advertises the surface low tracking across Indiana
and Ohio, which would bring some wrap-around precipitation to
portions of southern Indiana and northern Kentucky Tuesday into
early Wednesday. However, with a strong upper ridge in place, this
system will struggle dropping southeast like the GFS suggests.
Therefore, will favor the ECMWF and GFS ensembles, lifting the
surface low and its associated wrap-around precipitation further
north, thus keeping the forecast dry through the remainder of the
long term period.
&&
.Aviation (06Z TAF Issuance)...
Issued at 1232 AM EST Thu Feb 21 2013
Front half of the upcoming TAF period is fairly quiet as VFR
conditions will hold across the region with a very light
northeasterly surface flow. Clouds will increase throughout the
daytime hours as moisture streams in from the west. Initially dry
atmosphere will take some time to moisten up during the day but
precipitation looks to break out across the TAF sites towards 22/00Z.
Latest guidance continues to show the column moistening up during
the late afternoon hours. As column saturates to near the surface
by the evening hours, the evaporative cooling associated with the
moistening will allow surface temperatures to drop to near or just
below freezing at KSDF and KLEX. Warm air advection aloft will
result in a gradual warming above the sub-freezing layer at the
surface resulting in a profile for freezing rain and sleet to
develop. A mix of freezing rain and sleet looks increasingly likely
at KSDF between 22/02 and 22/06Z before low-level warm air advection
pushes surface temperatures up above freezing resulting in a change
back over to plain rain.
Over at KLEX, models prog stronger surface cooling resulting in a
period of freezing rain likely from 22/00Z through the end of the
TAF period. Depending on the amount of warm air aloft, some sleet is
possible, but it looks like the warm layer aloft will be
sufficiently deep enough to have precip generally in the form of
freezing rain. So for now, will just carry FZRA in the TAF from
22/00Z through the end of the period.
Further south at KBWG, low-level thermal profiles show plenty of
warm air to keep the precipitation as all rain Thursday night.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
KY...NONE.
$$
Short Term.......RJS
Long Term........KJD
Aviation.........MJ
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
353 AM CST Thu Feb 21 2013
.DISCUSSION...
Intense winter storm is taking direct aim on the forecast area this
morning. Overnight model runs...including the near-term RAP and
HRRR models...now indicate a broad swath of 1"+ liquid-equivalent
precipitation totals overspreading most of the forecast area with the
heaviest axis centered very close to Kansas City. How these precip
totals translate into snow and sleet amounts is still somewhat of a
question mark given the presence of warm air in the 800-700 hPa layer
and a shallow depth of the max dendritic growth region. Seems most
methods are giving snow to liquid ratios on the order of 8:1 to 10:1
near I-70...and around 10:1 to 12:1 north of Highway 36. Applying
these ratios to expected precip totals now results in a broad swath
of 8 to 12 inch snows forecast for most of the forecast
area...generally along and north of a Paola...Marshall...Moberly
line. These areas are unlikely to see much if any sleet
contamination and could see some totals approach or exceed February
records (see climate section below). Still expect sleet to fall across
areas south of this line, and there could be a good deal of it.
Exactly how much sleet falls across these areas will have huge
impacts on snow amounts, which could be as low as 3 or 4 inches if
sleet lasts several hours...to as much as 8 to 10 inches if sleet is
only brief. Freezing rain still appears a possibility for the
Clinton/Sedalia/Boonville areas but any icing should be limited to a
tenth of an inch or less.
Looking upstream, synoptic and mesoscale ascent has become quite
strong and is coupled throughout a large depth of the atmosphere.
Combine this with strong moisture advection from the south, the
result has been an expanding area of heavy precipitation over
northern OK and southern KS with several bands of convection feeding
into it. In fact, lightning profilers have lit up vividly down there,
even in the stratiform precipitation over KS, suggestive of quite a
bit of slantwise and even upright instability. This instability will
spread into ern KS/wrn MO through the morning and could easily
result in occasional thunder and snowfall rates of 2" to 3" per hour.
Heaviest precipitation band will spread into northern MO through the
afternoon and taper off across the KC area by 21Z or so. However,
broad synoptic scale and weak deformation forcing will continue well
into the evening and overnight as the upper low moves overhead. This
could result in an extra 2" to 5" of snow from late afternoon into
the early morning hours particularly north of the Missouri River.
Hawblitzel
Friday and Saturday...
As the system departs, a few lingering snow showers may be possible
across far northeast Missouri, but little to no additional snow
accumulation is expected. Temperatures will have difficulty rising
much on Friday with widespread snow cover and colder air advecting
into the region, so have kept high temperatures only a few degrees
warmer than Thursday night lows. Frigid temperatures are possible
Friday night as surface high pressure drifts over western Missouri,
combining the residual snow cover with light winds and clear skies.
Warmer air will begin to build into the region on Saturday as the
upper low departs, but reaching highs much above freezing will be
difficult, especially without strong return flow at low levels.
Sunday and Monday...
Another deep trough axis will swing through the four corners region
on Sunday, bringing a deepening surface low into the southern High
Plains by early Monday. This system is currently projected to lift
northeast into the region on Monday afternoon, taking a somewhat
similar track to the current system; however, there is still a good
deal of uncertainty in this forecast. Moisture may be a bit more
limited with a smaller window of time to draw from the Gulf, and
this more southern track is a very recent trend with the 00z models,
so for now have kept probabilities relatively low and maintained a
rain or snow precipitation type to cover several possible scenarios.
Tuesday through Thursday...
Quieter conditions should prevail for the remainder of next week as
a more persistent ridge builds over the west. A few snow showers may
be possible Tuesday night into early Wednesday as a weak clipper
dives in behind the departing upper low, but any snowfall that does
occur should be fairly light, and the probability of measurable snow
is low. Temperatures will remain below normal as a result of cold
air wrapping behind the upper low and additional cold air dropping
southeast with the clipper, but should eventually recover when the
ridge over the Rockies begins to shift east.
Laflin
&&
.CLIMATE...
The last time Kansas City officially measured 12" of snow was
January 18-19 in 1962 (14.0"). The most snowfall greater than 10" was
February 24-25 in 1993 (11.1").
Top 10 snowfalls for Kansas City
1. 24.2"...Mar 22-24 1912
2. 15.8"...Feb 11-12 1894
3. 14.6"...Jan 20-21 1958
4. 14.0"...Jan 18-19 1962
5. 13.8"...Mar 14-15 1960
6. 13.7"...Jan 8-9 1930
7. 13.0"...Feb 27-28 1900
8. 12.3"...Mar 29-31 1926
9. 12.2"...Dec 23-24 1918
10. 11.9"...Mar 3-5 1915
Top 5 daily February snowfalls for Kansas City
1. 11.8"...27th 1900
2. 10.5"...4th 1915
3. 8.7"...23rd 1990
4. 8.6"...2nd 1960
5. 8.0"...15th 1960
&&
.AVIATION...
For the 06Z TAFs...Thinks look to be on track for the winter storm
system that will affect the terminals beginning this morning.
Overnight conditions will remain VFR with a cloud deck between
6-7kft. Light returns showing up on radar will remain as virga as
the air in the lower 6kft will be very dry. By 14Z-15Z this dry air
will be overcome and cigs will quick drop into the MVFR category
with vsbys dropping 5SM with the onset of light snow. There will be
a period of moderate to occasionally heavy snow at the terminals
between 17Z-21Z at which point snow rates could be as high 2-3"
inches per hour thus making it difficult for snow removal on
runways. The heavy snow will also be accompanied by IFR and
occasional VLIFR cigs/vis with even the potential for thundersnow
which may be added to the TAF forecast as we get closer to the
event. Moderate snow is then expected to continue with IFR cigs/vis
through 23Z. Snow should begin to taper off becoming light by 23Z
however IFR cigs with vsbys improving to 1SM will continue through
the end of the TAF period. Winds overnight will be between 10-15kts
but will pick up tomorrow morning as the pressure gradient tightens
across the area. Winds tomorrow will be between 15-20kts with gusts
to 25-30kts however blowing snow is not expected to be a concern due
to the heavy nature of the snow. Winds will weaken somewhat by
tomorrow evening but still remain between 10-15kts with gusts to
25kts while backing to the east-northeast.
73
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER STORM WARNING until Midnight CST tonight FOR MOZ039-040-
045-046.
WINTER STORM WARNING until Midnight CST tonight FOR MOZ028>030-
037-038-043-044-053-054.
WINTER STORM WARNING until 6 AM CST Friday FOR MOZ001>004-
011>013-020-021.
WINTER STORM WARNING until 6 AM CST Friday FOR MOZ005>008-
014>017-022>025-031>033.
KS...WINTER STORM WARNING until Midnight CST tonight FOR KSZ057-060-
103>105.
WINTER STORM WARNING until 6 AM CST Friday FOR KSZ025-102.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1011 PM CST WED FEB 20 2013
.UPDATE...
ISSUED AT 928 PM CST WED FEB 20 2013
NOT A WHOLE LOT OF CHANGES TO THE FORECAST FOR TONIGHT ASIDE FROM
INCREASING SNOWFALL AMOUNTS IN OUR SOUTHWEST ZONES WHERE A 9 INCH
AMOUNT HAS BEEN RECEIVED IN PLAINVILLE KS IN ROOKS COUNTY. FARTHER
EAST...THE DRIER AIR HAS BEEN SLOW TO OVERCOME AND HAVE LOWERED
SNOWFALL AMOUNTS SLIGHTLY FOR OUR EAST/NORTHEAST ZONES. SNOW HAS
BEGUN TO INCREASE IN COVERAGE ACROSS OUR SOUTHWEST CWA AND THE
SNOW WILL SPREAD NORTH OVERNIGHT. OUR EASTERN AREAS COULD STILL
PICK UP AN INCH OR TWO PRIOR TO DAYBREAK...ALTHOUGH THE HIGHER
AMOUNTS WILL STILL BE REALIZED ACROSS SOUTHERN/WESTERN AREAS. THE
00Z RUN OF THE NAM REMAINS CONSISTENT WITH THE UPPER LOW LIFTING
NORTHEAST FM THE TX PANHANDLE THURSDAY MORNING INTO EAST CENTRAL
KS BY 00Z FRIDAY. DEFORMATION SNOWFALL WILL DEVELOP ACROSS KS
EARLY THURSDAY AND SPREAD NORTHWARD AS SYSTEMS LIFTS NORTHEAST
DURING THE DAY. WE ARE STILL LOOKING AT WIDESPREAD HEAVY SNOWFALL
DEVELOPING IN KS THURSDAY MORNING AND SPREADING INTO NEBRASKA BY
THURSDAY AFTN AND CONTINUING INTO THE EVENING. 00Z NAM STORM TOTAL
SNOWFALL REMAINS CONSISTENT WITH PREVIOUS RUNS AND OTHER MODELS
WITH POTENTIAL OF 10 INCHES OR MORE OF SNOW...WITH WELL OVER A
FOOT POSSIBLE ACROSS NC KS INTO SW/SC NEB.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 239 PM CST WED FEB 20 2013
TONIGHT THROUGH EARLY FRIDAY MORNING...FOCUS CONTINUES
TO BE ON THE APPROACHING UPPER LEVEL DISTURBANCE CURRENTLY VISIBLE
IN WATER VAPOR IMAGERY CIRCULATING ACROSS CENTRAL ARIZONA. MOISTURE
AHEAD OF THIS DISTURBANCE HAS BEEN SURGING NORTHWARD FOR MUCH OF THE
DAY TODAY...WITH LIGHT SNOW SLOWLY SPREADING NORTHWARD INTO PORTIONS
OF SOUTH CENTRAL NEBRASKA THE PAST FEW HOURS. EXPECT THIS LIGHT SNOW
TO CONTINUE THROUGH THE EVENING HOURS...AND INTENSIFY SOME
OVERNIGHT. WITH THE OVERALL SLOWER AND MORE SOUTHEASTWARD TRACK OF
THIS SYSTEM...NOW EXPECT THE HEAVIEST SNOWFALL TO DEVELOP IN BANDS
ACROSS NORTH CENTRAL KANSAS DURING THE EARLY MORNING HOURS
THURSDAY...WORKING ITS WAY INTO SOUTH CENTRAL NEBRASKA BY MID
MORNING. THAT SAID...STILL EXPECT SOME SNOWFALL ACCUMULATIONS THIS
AFTERNOON AND EVENING...ESPECIALLY ACROSS THE SOUTHWESTERN SECTIONS
OF THE FORECAST AREA...WITH LIGHT SNOWFALL POSSIBLY NOT WORKING INTO
THE EASTERN FRINGES OF THE LOCAL AREA UNTIL ABOUT MIDNIGHT.
LATEST RAP CONTINUES TO BE THE MAIN OUTLIER HOLDING OFF WIDESPREAD
SNOW UNTIL AROUND DAYBREAK THURSDAY FOR MUCH OF THE EASTERN HALF OF
THE FORECAST AREA...DUE TO ITS DEPICTION OF A MORE SIGNIFICANT DRY
LAYER NEAR THE GROUND IN THE LOW LEVEL EASTERLY FLOW. HOWEVER...WITH
THE NAM/SREF/GFS/EC/WRF ALL DEVELOPING MORE WIDESPREAD PRECIPITATION
BEFORE THEN...MOSTLY DISCOUNTED RAP ANALYSIS...AND KEPT ONSET OF
PRECIPITATION SIMILAR TO THIS MORNINGS FORECAST. OTHERWISE...WHILE
THE OVERALL TIMING OF THE MAIN SYSTEM ACROSS THE DESERT SOUTHWEST
HAS SLOWED DOWN A BIT IN THE 12Z MODELS...IT STILL LOOKS TO BE A
MAJOR WINTER STORM EVENT...AND HAVE ADJUSTED FOR THE SLOWER ANALYSIS
BY EXTENDING THE WINTER STORM WARNING FOR THE NORTH/NORTHEASTERN
HALF OF THE AREA BY 6 HOURS. AND WHILE OVERALL LIQUID EQUIVALENTS
HAVE COME DOWN TO AROUND AN INCH FOR THE TRI CITIES AREA WITH THIS
SYSTEM...RANGING FROM AROUND 0.75 IN THE EC TO AROUND 1.2 IN THE
NAM...INCREASED SNOWFALL RATIOS TO BE SLIGHTLY HIGHER THAN
PREVIOUSLY THOUGHT IN THIS COLD AIRMASS...SO ONLY VERY MINOR TWEAKS
ARE EVIDENT IN THE OVERALL SNOWFALL ACCUMULATIONS.
IN ADDITION TO SNOWFALL...EXPECT BREEZY SOUTHEASTERLY WINDS TO
CONTINUE THROUGH THE EVENING AND OVERNIGHT HOURS...AS THE PRESSURE
GRADIENT BEGINS TO TIGHTEN AHEAD OF THE APPROACHING SURFACE LOW.
WINDS ARE THEN EXPECTED TO EVENTUALLY RELAX AND SHIFT MORE NORTHERLY
ON THE BACKSIDE OF THE SURFACE LOW AS IT CROSSES INTO MISSOURI AND
IOWA BY TOMORROW EVENING. HOWEVER...WITH LOTS OF FAIRLY DRY SNOW AND
BREEZY WINDS...VISIBILITIES ARE EXPECTED TO BE REDUCED IN AREAS OF
BLOWING SNOW THROUGH THE DURATION OF THIS EVENT...NOT IMPROVING TIL
AFTER 00Z...AND KEPT AREAS OF BLOWING SNOW IN THE FORECAST AS A
CONSEQUENCE.
TEMPERATURES THROUGH THIS EVENT ARE EXPECTED TO REMAIN ON THE COLD
SIDE OF CLIMATOLOGY FOR MID FEBRUARY...WITH AFTERNOON HIGHS ON
THURSDAY LIKELY NOT RISING MUCH ABOVE THE MORNING LOWS AS THE CLOUD
COVER AND SNOW WILL PUT A CAP ON HEATING ACROSS THE LOCAL AREA.
TEMPERATURES ARE THEN EXPECTED TO PLUMMET FRIDAY MORNING ON THE
BACKSIDE OF THIS SYSTEM...AS SOME CLEARING ALONG WITH RELAXING WINDS
AND FRESH SNOW COVER SHOULD ALLOW FOR GOOD RADIATIONAL COOLING BY
EARLY FRIDAY MORNING.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 239 PM CST WED FEB 20 2013
PATTERN: THIS IS A STORMY PATTERN AND EXCITING IF YOU/RE A WINTER WX
FAN. WE ARE LIKELY TO SEE WINTERS FURY CONTINUE FULL BORE THRU THE
END OF THE MONTH. THIS MEANS AT LEAST ONE MORE SNOW/WIND STORM AND
COLDER THAN NORMAL DAYTIME TEMPS...WITH SEVERAL DAYS OF MUCH BELOW
NORMAL /ANYTHING 33F OR BELOW/. THE -PNA/-NAO IS DICTATING THE
LONG-WAVE PATTERN WHICH FEATURES A STORMY WRN USA TROF AND
INCREASING DOWNSTREAM BLOCKING OVER ERN N AMERICA.
FOR THOSE NOT EXCITED ABOUT WINTER WX...THE PNA WILL REACH ITS
LOWEST POINT THIS WEEK AND THEN TURN POSITIVE THE 1ST WEEK OF MAR.
THE ANOMALOUS E PAC RIDGE /+2 STANDARD DEVIATION HGTS/ WILL TAKE A
BIG HIT NEXT MON-TUE FROM A DEEPENING GULF OF AK STORM. THIS WILL
INITIATE THE RETROGRESSION AND REPOSITION THE LONG-WAVE TROF FURTHER
W...INDUCING A RIDGE OVER THE WRN USA NEXT WED.
HAZARDS: THERE IS POTENTIAL FOR ANOTHER WINTER STORM SUN NGT-MON
WITH APPRECIABLE AMOUNTS OF SNOW POSSIBLE.
UPCOMING PCPN OPPORTUNITIES: 2/25.
FRI THE STORM CONTINUES TO EXIT. ANOTHER PIECE OF ENERGY MOVES
THRU SAT...ON THE BACKSIDE OF THE TROF. THE NEXT POTENT TROF DIVES
INTO THE INTERMOUNTAIN W IN THE MEANTIME...AND DEEPENS SUN-MON AS
WAVELENGTH DECREASES. ANOTHER VORT MAX FOLLOWS INTO THE DESERT SW
TUE AND THIS ODDS FAVOR THIS STORM BEING SUPPRESSED FAR TO OUR S.
THE DAILY DETAILS...
CONFIDENCE IS BELOW AVERAGE ON OUR DAYTIME HIGHS THRU THE PERIOD
SINCE MODELS STRUGGLE WITH SUBSTANTIAL SNOW-PACK ON THE GROUND. WE
MAY NOT BE COLD ENOUGH.
FRI: CLEAN-UP AND RECOVERY BUT VERY COLD WITH PLENTY OF CLOUDS. ANY
BREAKS THAT DEVELOP WILL FILL BACK IN UNDER THERMAL TROF. CANT
COMPLETELY RULE OUT A STRAY AFTN FLURRY. WINDS NOT BAD.
SAT: QUIET INTERLUDE. CONFIDENCE IS AVERAGE. WOULDNT RULE OUT SOME
FLURRIES...BUT LOW-LEVEL MSTR APPEARS LIMITED.
SAT NGT: MAINTAINED CONTINUITY WITH PREVIOUS FCST FOR A SLGT CHANCE
OF FRZG DRZL...BUT WITH LOW CONFIDENCE. INCREASING LOW-LEVEL MSTR
OVER A COLD SNOW PACK COULD RESULT IN STRATUS. DID REMOVE FLURRIES
FROM THE FCST. LOW-LEVEL THERMAL PROFILES MAY NOT BE COLD ENOUGH
FOR SNOW GRAINS.
SUN: BACKED DOWN POPS TO SLGT CHANCE.
SUN NGT-MON: THIS STORM COULD BE TROUBLE. COORDINATED WITH HPC AT
1530Z. BELIEVE THIS STORM TAKES A VERY SIMILAR TRACK TO THE CURRENT
STORM. THE DIFF IS THIS STORM IS WE/RE GETTING A SIGNAL THAT IT
LINGERS OR STALLS OVER ERN KS DURING THE DAYLIGHT HRS MON...BEFORE
SLOWLY HEADING TOWARD THE GREAT LAKES MON NGT-TUE.
ACCUMULATING/PLOWABLE SNOW REQUIRING WATCHES/WARNINGS/ADVISORIES
APPEARS LIKELY BASED ON TRENDS IN THE LAST 72 HRS. BUT THIS DOES
NOT NECESSARILY MEAN FOR OUR ENTIRE FCST AREA. POPS HAVE BEEN
INCREASED TO 60-70%. THINK WE NEED TO PREPARE FOR THE OPTION OF A
SLOW-MOVING...POSSIBLY LONG-LIVED STORM. THE BLOCKING HIGH
DOWNSTREAM URGES CAUTION.
THIS STORM HAS POTENTIAL TO BE VERY WINDY.
MODELS: 1456Z PMDEPD AND HPC GUIDANCE REVIEWED AND WE ARE IN
AGREEMENT ON A SLOWER SOLUTION PER THE EC/GEM ENSEMBLES. MOST GFS
ENSEMBLE MEMBERS LOOK TOO FAST/PROGRESSIVE AS EARLY AS 12Z/SUN. EVEN
THE HIGHER RES OPERATIONAL GFS RUNS ARE TOWARD THE SLOWER PACK.
TUE: CYCLONIC FLOW GRADUALLY RELEASES BUT STILL EXPECT PLENTY OF
CLOUDS THRU MIDDAY UNDER THERMAL TROF. BEST IMPROVEMENT S AND W OF
TRI-CITIES.
WED: QUIET AND DRY.
NAO/PNA TELECONNECTIONS: THESE REFER TO THE NORTH ATLANTIC
OSCILLATION AND PACIFIC-NORTH AMERICAN OSCILLATION. THESE
OSCILLATIONS DEAL WITH RIDGES/TROFS AND PATTERNS IN THE JET
STREAM. THE VARIOUS CONFIGURATIONS DICTATE WHAT OUR SENSIBLE
WEATHER WILL BE...ABOVE OR BELOW NORMAL TEMPS...AND DRIER OR
WETTER THAN NORMAL.
-PNA: THIS IS A TROF OVER THE WRN USA. COLDER AND STORMIER FOR THE
CNTRL PLAINS.
+PNA: THIS IS A RIDGE OVER THE WRN USA. THIS IS A QUIET AND MILD
PATTERN HERE.
THE NAO IS MOSTLY A PLAYER IN OUR STORM TRACKS HERE ON THE PLAINS.
+NAO: NO BLOCKING IN THE ATMOSPHERE NEAR GREENLAND. AT TIMES...
THIS ALLOWS COLORADO LOWS TO TRACK MORE ACROSS NEB.
-NAO: BLOCKING NEAR GREENLAND. THIS TENDS TO FORCE COLORADO LOWS
TO OUR S...ACROSS KS.
THIS WEBSITE HAS ADDITIONAL INFO...SOME OF WHICH IS TECHNICAL.
CHECK OUT THE MAPS THAT INDICATE INDICATE THE POSITIVE PHASES.
WARM COLORS INDICATE WARMER TEMPS AND DECREASED STORMINESS. COLD
COLORS INDICATE COLDER TEMPS AND INCREASED STORMINESS. FOR THE
NEGATIVE PHASES...JUST REVERSE THE COLORS. THESE TELECONNECTIONS
HAVE THE GREATEST IMPACTS IN THE COOLER MONTHS OF THE YEAR.
WWW.CPC.NCEP.NOAA.GOV/DATA/TELEDOC/TELEINTRO.SHTML (ALL LOWER CASE)
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1005 PM CST WED FEB 20 2013
SNOW WILL CONTINUE TO FALL INTERMITTENTLY THROUGH THE NIGHT WITH
THE HEAVIEST SNOWFALL EXPECTED FROM MIDDAY THURSDAY THROUGH THE
AFTERNOON AND EVENING AS A POTENT WINTER STORM SYSTEM CROSSES THE
CENTRAL PLAINS. STEADY EASTERLY WINDS OVERNIGHT WILL TRANSITION
NORTHEAST AND NORTHERLY THURS AFTN AND EVENING. CIGS AND VSBYS
WILL BE DEPENDENT ON TIMING OF SNOW BANDS WITH LIFR CONDITONS
LIKELY THURS AFTN/EVE.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...WINTER STORM WARNING UNTIL MIDNIGHT CST THURSDAY NIGHT FOR
NEZ039>041-046>049-060>064-072>077-085>087.
WINTER STORM WARNING UNTIL 6 PM CST THURSDAY FOR NEZ082>084.
KS...WINTER STORM WARNING UNTIL 6 PM CST THURSDAY FOR KSZ005>007-
017>019.
&&
$$
UPDATE...FAY
SHORT TERM...ROSSI
LONG TERM...HALBLAUB
AVIATION...FAY
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
223 AM EST THU FEB 21 2013
.SYNOPSIS...
A NORTHWEST FLOW OF COLD AIR ACROSS THE FINGER LAKES WILL KEEP
LAKE EFFECT SNOW SHOWERS OVER CENTRAL NEW YORK INTO THURSDAY...
ALTHOUGH THE SNOW SHOWERS WILL WEAKEN AS HIGH PRESSURE BUILDS IN
AND SLOWLY CLEARS OUR SKIES. IT WILL REMAIN MOSTLY DRY ON FRIDAY
BEFORE A COMPLEX STORM SYSTEM OVER THE GREAT LAKES AND MID
ATLANTIC COAST PUSHES MIXED PRECIPITATION INTO THE AREA.
&&
.NEAR TERM /THROUGH TODAY/...
950 PM UPDATE...
LAKE BAND IS FINALLY SHOWING SIGNS OF A SOUTHWARD PUSH. WILL
CONTINUE GRID FORECAST UPDATED A FEW YEARS AGO, WITH THE NEXT
TARGET BECOMING NORTHERN ONONDAGA COUNTY. BAND IS STILL FORECAST
TO WEAKEN QUICKLY DUE TO COLLAPSING INVERSION HEIGHTS.
750 PM UPDATE...
STILL NO MOVEMENT SOUTHWARD TO LAKE BAND, WHICH IS SHOWING A
LITTLE MORE ORGANIZATION DEVELOPING. LATEST RAP DROPS THE BAND
INTO ONONDAGA COUNTY AROUND 3Z AND WEAKENS IT THEREAFTER.
AT THIS POINT I HAVE A HEALTHY DOSE OF SKEPTICISM REGARDING THE
NEWEST MESOSCALE MODEL RUNS, AS OTHERS HAVE HANDLED THE SITUATION
POORLY. SFC WIND AND PRESSURE OBSERVATIONS ARE NOT SUGGESTING A
BIG MOVE COMING. COULD ARGUE FOR EXTENDING THE ADVISORY FOR N.
ONEIDA, BUT DO NOT ANTICIPATE MORE THAN AN ADDITIONAL INCH OR TWO
TONIGHT.
610 PM UPDATE...
LAKE EFFECT BAND IS DEFYING THE SHORT TERM MODELS, AND IS
RESISTING THE FORECAST TO DRIFT SOUTHWARD INTO ONONDAGA COUNTY.
THE BAND HAS ALSO WEAKENED CONSIDERABLY IN THE LAST HOUR, THOUGH
WITH NIGHTTIME UPON US AND DAYTIME THERMALS LONG GONE, IT WOULD NOT
BE SURPRISING TO SEE REORGANIZATION.
THE GRIDS HAVE BEEN ADJUSTED TO DELAY THE LES ONSET INTO ONONDAGA-
MADISON BY 1-2 HOURS. WILL CONTINUE TO MONITOR BAND STRENGTH ONCE
IT MAKES ITS MOVE FOR POTENTIAL ADVISORY. SHOULD CURRENT RADAR
TRENDS HOLD, THERE WILL BE NO NEED FOR A FLAG.
3 PM UPDATE...
MESO SCALE MODELS AND FCST SNDGS SHOW THE BAND SLOWLY DRFTG
SOUTH OVRNGT AND WEAKENING. CRNT KTYX 88D IMAGES SHOW A SOMEWHAT
MORE DISORGANIZED BAND NOW IN THE ADVISORY AREA AND INDEED VERY
SLOWLY MVG SOUTH. SOMEWHAT CNRND THAT ANOTHER SPOKE ROTATING ARND
THE UPR LOW COULD DELAY THE SWRD MVMT AND QUICKLY GIVE PART OF THE
FCST AREA NEAR ADVISORY SNOW THIS EVE. AIR STILL PLENTY COLD WITH
-14C AIR CORE OVER THE LAKE. HWVR...SINKING MOTION SHOWN IN THE
SNDGS CONTS TO LWR THE INV PTNLY WEAKENING THE BAND REGARDLESS OF
THE FLOW. ATTM WILL CONT WITH THE ADVISORY FOR NRN ONEIDA AND PUT
ACCUMS JUST BLO CRITERIA IN NRN ONONDAGA AND SRN ONEIDA.
&&
.SHORT TERM /TONIGHT THROUGH SATURDAY/...
LE WILL LINGER INTO THU WITH CONTD COLD AIR AND NW FLOW. HIPRES
SFC AND ALOFT FNLY BLDS IN FOR FRI AS THE CLSD LOW DRIFTS EAST IN
RESPONSE TO THE DVLPG COMPLEX OVER THE CNTR OF THE COUNTRY. FRI
LOOKS SUNNY WITH SLGTLY ABV NRML TEMPS.
COMPLEX SCENARIO AND TRICKY FCST UNFOLDING FOR THE END OF THE SHRT
TERM. YET ANOTHER CLSD LOW OVER THE GREAT LAKES TRIES TO PHASE
WITH A SRN STREAM SHRT WV TRAVELING UP THE EAST CST. MODELS
TYPICALLY HAVE TROUBLE WITH DVLPG LOWS AND THIS IS COMPLICATED BY
THE DFCLTY IN PLACING THE MEANDERING CLSD UPR LOW OVER THE WRN
LAKES. CONSENSUS NOW IS TO DVLP THE SRN STREAM IMPULSE ENOUGH TO
PUSH MORE SUBSTANTIAL PCPN BACK INTO THE SERN ZONES...NAMELY THE
PA AND THE WRN CATS. OTR COMPLICATING FACTOR IS PCPN TYPE WITH A
COMPLETE LACK OF COLD AIR...EVEN OVER NRN NEW ENG. SO...IT LOOKS
VERY MUCH LIKE AN EARLY SPRING LIKE SCENARIO WITH MIXED PCPN...OR
LRG VLY/HILL DFRNCS. CNRT WWE FCST GIVE THE SERN ZONES A 4 TO 6
INCH ACCUM...2 TO 4 ELSEWHERE. WILL CONT A MENTION IN THE HWO FOR
NOW AND XPCT CONTG CHGS TO THE FCST AS THE WEEKEND APRCHS.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
1 PM UPDATE...
BLOCKY PATTERN WITH TWO CLOSED LOWS MOVING THROUGH IN THE LONG
TERM. BOTH APPEAR TO BE MINOR FOR THE CWA. THE FIRST WILL BE
FRIDAY TO SUNDAY. THE UPPER LEVEL LOW WILL BE IN THE GREAT LAKES
SAT NGT WITH A NOREASTER FORMING. MOST MODELS HAVE A NEAR MISS.
THE TROF GOES NEGATIVE TILT WHICH SLOWS THE SNOW FROM EXITING
UNTIL SUNDAY. A WEAK LAKE RESPONSE ON THE BACK SIDE OF THE STORM
SUNDAY NIGHT TO MONDAY. LATE MONDAY A LARGE AREA OF HIGH PRESSURE
MOVES IN AT THE SFC AND ALOFT.
TUESDAY TO WEDNESDAY DO IT ALL OVER AGAIN WITH ANOTHER STACKED
LOW. THE EURO HANDLES THIS STORM SLOWER WITH THE LOW IN ILLINOIS
TUES MORN MOVG TO SSM WED. WARM AIR COMES NORTH WITH THE OCCLUDED
FRONT SO PRECIP WILL BE MIXED. THE GFS BRINGS THE STACKED LOW ENE
OVER NY/PA SO A BETTER CHC OF SNOW.
&&
.AVIATION /07Z THURSDAY THROUGH MONDAY/...
06Z UPDATE...
A COLD NORTHWEST FLOW WILL PERSIST THROUGH THIS TAF PERIOD
BRINGING A CONTINUATION OF SNOW SHOWERS AND FLURRIES. THE BEST
CHANCE FOR MORE ORGANIZED LAKE SNOWS WILL BE THROUGH 12Z
ESPECIALLY AT KSYR AND KRME...WITH A GRADUAL TRANSITION TO LIGHTER
SNOW FLURRIES AND SHOWERS FOR THE REMAINDER OF THURSDAY.
AT KRME...GENERALLY IFR WILL CONTINUE THROUGH 09Z IN STEADYER SNOW
SQUALLS. AFTER 09Z THE HEAVIER BAND WILL THEN DROP SOUTH OF THE
TERMINAL WITH MVFR SNOW SHOWERS EXPECTED THROUGH DAYBREAK WITH A
GRADUAL RETURN TO VFR WITH CIGS AROUND 3,500 FT AFTER THAT TIME.
AT KSYR...IFR WITH OCCASIONAL BELOW ALT MIN CONDITIONS THROUGH
09Z. AFTER 09Z SOME IMPROVEMENT POSSIBLE BUT CONFIDENCE NOT HIGH
ENOUGH AND ELECTED TO KEEP THE POSSIBILITY OF IFR VSBYS IN THROUGH
12Z. AFTER THAT TIME WE SHOULD IMPROVE TO MVFR IN SNOW SHOWERS AND
FLURRIES THROUGH AFTERNOON.
AT KITH/KBGM...GENERALLY MVFR CONDITIONS DUE TO CIGS WITH
OCCASIONAL MVFR VSBY RESTRICTIONS IN SNOW SHOWERS THROUGH
DAYBREAK. FLURRIES AND BRIEF HEAVIER SQUALLS LIKELY TO PERSIST THROUGH
THURSDAY AFTN AT KITH.
AT KELM/KAVP...GENERALLY VFR WITH CIGS AROUND 4K FT AND SNOW FLURRIES.
WEST WINDS 10-15 KNOTS WITH GUSTS AROUND 25 KNOTS DURING THE
DAYLIGHT HOURS ON THURSDAY.
.OUTLOOK...
THU NGT/FRI MORN...VFR.
FRI AFTN TO SAT NGT...MVFR/IFR IN MIXED PCPN.
SUN...VFR...MAYBE MVFR IN NY WITH LAKE ENHANCED SNOW SHOWERS.
MON...VFR.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...DGM
NEAR TERM...DGM/DJP
SHORT TERM...DGM
LONG TERM...TAC
AVIATION...HEDEN/RRM
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
311 AM CST THU FEB 21 2013
.SHORT TERM...(TODAY THROUGH SATURDAY NIGHT)
CHALLENGE WILL BE TEMPERATURES AND LIGHT SNOW CHANCES. 00Z MODELS
IN AGREEMENT AND WILL USE A BLEND FOR THE FORECAST. NO BIG CHANGES
REQUIRED TO THE FORECAST.
COULD BE SOME FLURRIES OR VERY LIGHT SNOW ACROSS THE DEVILS LAKE
BASIN THIS MORNING...BUT MODELS ALL INDICATE RIDGING AND LOW LEVEL
EASTERLY DRY FLOW WILL KEEP ACCUMULATING SNOWFALL TO THE WEST.
HAVE REMOVED POPS/WX FOR TODAY INTO THE EVENING HOURS. AFTER
MIDNIGHT...UPPER LOW WILL TRACK INTO IOWA AND CONTINUE SLOWLY INTO
NORTHERN WISCONSIN BY FRIDAY EVENING. THE SOUTHEAST FA WILL BE
NEAR THE NORTHERN END OF SNOW SHIELD...AND MODELS ALL AGREE AROUND
AN INCH OF SNOW POSSIBLE ON BY FRIDAY AFTERNOON. KEPT THE IDEA OF
HIGH POP/LOW QPF. RIDGING THEN DOMINATES ON SATURDAY.
TEMPERATURES WILL BE CHALLENGING AND HIGHLY DEPENDENT ON CLOUD
COVER...ESPECIALLY AT NIGHT. FOR TODAY...WITH SOLAR EXPECTED
ACROSS THE EASTERN FA...THINKING THE FORESTED AREAS WILL BE ABLE
TO WARM INTO THE MID/UPPER 20S. WITH A WARMER START COMPARED TO
YESTERDAY...THE REMAINDER OF THE FA SHOULD BE ABLE TO WARM INTO
THE TEENS. MID-UPPER CLOUDS EXPECTED TO OVERTAKE THE REGION
TONIGHT...WHICH WILL LIMIT TEMPERATURE FALL. THE MAIN QUESTION
WILL BE AREAS THAT ARE CLEAR THIS EVENING...AND HOW FAR THEY WILL
FALL BEFORE CLOUDS ARRIVE. ON FRIDAY...EXPECT MOSTLY CLOUDY SKIES
WHICH WILL LIMIT MAX TEMPS ACROSS THE REGION TO AROUND 20F. WEAK
FLOW AND SIMILAR AIRMASS TEMPERATURES REMAIN INTO SATURDAY. IF
THERE IS SOLAR ON SATURDAY EXPECT THE FORESTED AREAS TO BE
WARMER...AND IF/WHERE SKIES ARE CLEAR AT NIGHT EXPECT VALUES JUST
BELOW ZERO. DID LOWER MIN TEMPS A BIT...BUT NOT TOO CRAZY.
.LONG TERM...(SUNDAY THROUGH WEDNESDAY)
MEDIUM-RANGE MODELS AGREE THAT THE NORTHERN PLAINS WILL BE IN A
SPLIT FLOW PATTERN WITH THE MAJORITY OF SYNOPTIC ENERGY ACROSS THE
SOUTHERN CONUS. ANOTHER FOUR CORNERS LOW AND ITS SNOW MAY CLIP THE
SOUTHEASTERN FORECAST AREA EARLY NEXT WEEK...BUT OVERALL MODEL
TRENDS CONTINUE TO KEEP THE MAJORITY OF PRECIPITATION SOUTH AND EAST
INTO MN/WI/IA. SEVERAL WEAK WAVES COULD IMPACT THE REGION THROUGH
THE PERIOD...BUT MODEL TIMING AND PLACEMENT AGREEMENT IS POOR. AS A
RESULT...WILL KEEP LOW-END (20-30 PERCENT) ALL BLEND POPS. WITH NO
MAJOR CHANGES IN AIR MASS...EXPECT LITTLE DAY TO DAY TEMPERATURE
VARIATION. AFTERNOON HIGHS WILL BE IN THE 20S AND NIGHTTIME LOWS
WILL BE IN THE TEENS.
&&
.AVIATION...
EXPECT VFR CONDITIONS WITH SOME LOWER VFR CIGS NEAR KDVL FOR
TODAY. WILL NEED TO MONITOR THE POTENTIAL FOR LOWER CIGS ADVECTING
INTO THE REGION FROM THE EAST THIS EVENING. 06Z RAP INDICATES
LOWER CIGS ACROSS NORTHERN WISCONSIN WILL EXPAND. CONFIDENCE IS
LOW THAT THIS WILL ACTUALLY OCCUR...BUT SOMETHING TO MONITOR.
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
TG/ROGERS
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1133 PM CST WED FEB 20 2013
.AVIATION...
WILL MAINTAIN CONTINUITY OF PREVIOUS FORECASTS CONCERNING TIMING
OF SQUALL LINE AND COLD FRONT. HOWEVER...WE DID MODIFY THE TIMING
OF LOWERING CLOUD BASES AND ARRIVAL OF IFR CIGS ACROSS THE
METROPLEX AND KACT.
SHRA ACTIVITY WILL INCREASE FOR KACT AFTER 07Z AS THE SFC-850 FRONT
LIFTS NORTHWARD AND FORCING FOR LIFT INCREASES. AS FOR THE
METROPLEX...WE/RE LOOKING FOR THIS PROCESS TO GEAR UP 08-10Z. THE
TIMING OF THE SQUALL LINE STILL LOOKS GOOD...13-16Z FOR THE
METROPLEX AND 14-16Z FOR KACT.
LOW-LEVEL WIND SHEAR WILL REMAIN A PROBLEM TONIGHT AS LOCAL 88D RADAR
VAD PROFILES SHOW 50+ KNOTS AROUND 2-3 KFT AND GENERALLY 25-30
KNOTS AT 1 KFT AGL. HAVE INCLUDE THIS CAUTION IN ALL TAFS. 75
&&
.UPDATE...
A MINOR UPDATE TO LOWER RAIN CHANCES THROUGH LATE EVENING INTO THE
FIRST FEW HOURS OF THURSDAY MORNING...AS NORTH TEXAS IS IN A LULL
BETWEEN DISTURBANCES. THE FIRST DISTURBANCE THAT GAVE THE RAIN AND
A LITTLE BIT OF SLEET TO PARTS OF NORTH TEXAS EARLIER TODAY IS
HEADING AWAY FROM THE AREA AND CAUSING WINTER WEATHER PROBLEMS
ACROSS PARTS OF OKLAHOMA INTO ARKANSAS/MISSOURI.
THE MAIN SYSTEM THAT WILL AFFECT NORTH TEXAS BY DAYBREAK THURSDAY
MORNING IS JUST STARTING TO ROTATE OUT OF ARIZONA AND INTO WESTERN
NEW MEXICO AT 9 PM. LINEAR FORCING WAS HELPING TO DEVELOP A LINE
OF STORMS ACROSS FAR SOUTHEAST NEW MEXICO AND TO THE TEXAS STATE
LINE. NOT ALL MODELS ARE IN SUCH AS THE 00Z GFS...HOWEVER THE 00Z
NAM...TEXAS TECH WRF AND HRRR MODELS ARE SHOWING IT WILL BE AFTER
3 AM BEFORE THINGS BEGIN TO GET ACTIVE ACROSS THE WESTERN HALF OF
THE AREA. ONE THING TO NOTE OF THE WRF AND 00Z NAM MODELS HOWEVER
WAS THEY WERE TOO FAR EAST FROM LUBBOCK TO MIDLAND WITH THE
DEVELOPING SQUALL LINE AT MID EVENING.
THE SURFACE WARM FRONT WHICH IS NOW OVER SOUTH-CENTRAL TEXAS WILL
ONLY CREEP NORTH WITH THE BEST NORTHWARD SURGE OCCURRING WEST/SOUTHWEST
OF OUR AREA CLOSER TO THE BETTER HEIGHT FALLS AND SURFACE LOW
CURRENTLY OVER ALPINE AND FAR WEST TEXAS. STRONG 850MB WAA WILL SLIDE
EAST ACROSS WESTERN NORTH TEXAS BETWEEN 3-6 AM...AND THIS WILL BE
THE TIME STORMS AND A FEW SUPERCELLS WILL DEVELOP. BEST CHANCE FOR
SURFACE-BASED SEVERE STORMS WITH DAMAGING WINDS AND TORNADOES WILL
BE IN A LIMITED TIME WINDOW FROM 5AM-9AM AND GENERALLY SOUTH OF A
HAMILTON-WACO-ATHENS OR PALESTINE LINE. WITH 0-6KM SOUTHWESTERLY
SHEAR ON THE ORDER OF 70-90 KTS AND SOMEWHAT VEERED 0-1KM ON THE
ORDER OF 40-50 KTS...SUPERCELLS ARE HIGHLY LIKELY. ELEVATED
SUPERCELLS WILL OCCUR NORTH OF THE WARM FRONT WITH VERY LARGE
HAIL...FREQUENT LIGHTNING...AND HEAVY DOWNPOURS THE MAIN THREATS.
WE WILL CONTINUE TO MONITOR THIS SYSTEM DURING THE OVERNIGHT AND
URGE EVERYONE TO KEEP ON EYE THINGS AS THEY WAKE UP AND BEFORE
HEADING OUT FOR THE MORNING COMMUTE THURSDAY MORNING. SPOTTER AND
HAMS COULD EASILY BE ACTIVATED ACROSS THE WESTERN HALF OF THE CWA
BEFORE SUNRISE.
05/
&&
.PREV DISCUSSION... /ISSUED 330 PM CST WED FEB 20 2013/
CLOUDY AND COOL CONDITIONS PERSIST ACROSS THE REGION THIS
AFTERNOON WITH JUST A FEW SCATTERED AREAS OF LIGHT RAIN/SHOWERS
ACROSS THE REGION. THE UPPER LEVEL SYSTEM THAT WE HAVE BEEN
MONITORING TO BRING US STORMS AND A THREAT FOR SEVERE WEATHER
TONIGHT/THURSDAY IS NOW MOVING INTO SOUTHERN ARIZONA. THE
ASSOCIATED PACIFIC FRONT IS ALSO MOVING INTO ARIZONA...AND THIS
ENTIRE SYSTEM HAS QUITE A WAYS TO TRAVEL BEFORE ARRIVING IN NORTH
AND CENTRAL TEXAS.
FOR THE REST OF TODAY AND EARLY TONIGHT...RAIN ACTIVITY WILL BE
ISOLATED TO SCATTERED IN NATURE BUT OVERALL IT WILL BE A QUIET
EVENING. THEREFORE LOWERED POPS FOR THE EVENING HOURS AND ALSO
REMOVED THE MENTION OF THUNDER. THE RAIN ACTIVITY THROUGH THE
NIGHT WILL MAINLY COME FROM INCREASING ISENTROPIC LIFT ASSOCIATED
WITH WARM AIR ADVECTION OVER THE COOL SURFACE BOUNDARY LAYER. MUCH
LATER TONIGHT...LIFT FROM THE APPROACHING UPPER LEVEL LOW WILL
BEGIN TO SPREAD OVER THE REGION AND WILL LIKELY SEE AN INCREASE IN
CONVECTIVE/THUNDERSTORM ACTIVITY DURING THE OVERNIGHT HOURS.
AS THE UPPER LEVEL LOW APPROACHES THE TEXAS PANHANDLE
OVERNIGHT...A LINE OF STORMS IS EXPECTED TO DEVELOP ALONG THE
PACIFIC FRONT AND SWEEP EAST ACROSS THE REGION. THE LATEST HI-RES
AND SHORT TERM GUIDANCE IS NOW SLOWER WITH THE DEVELOPMENT AND
MOVEMENT OF THIS LINE OF STORMS...THUS MADE MINOR ADJUSTMENTS TO
POPS TOMORROW BASED ON THIS SLOWER TIMING. MOST SHORT-TERM
GUIDANCE HAS THE FRONT/LINE OF STORMS ALONG OUR WESTERN BORDER
AROUND 11Z/5 AM CST...GIVE OR TAKE AN HOUR. THIS WOULD PUT THE
LINE OF STORMS ALONG THE I-35 CORRIDOR AROUND MID MORNING AND THEN
MOVING OUT OF OUR EASTERN COUNTIES AROUND MIDDAY. WITH GOOD
AGREEMENT AMONG MANY OF THE MODELS ON THIS SLOWER
TIMING...CONFIDENCE IS FAIRLY HIGH THAT THE SYSTEM WILL TAKE
SLIGHTLY LONGER TO ARRIVE THAN PREVIOUSLY THOUGHT...ESPECIALLY
WITH THE UPPER LEVEL LOW STILL OUT IN ARIZONA.
WITH LARGE SCALE LIFT SPREADING OVER THE AREA OVERNIGHT AND WARM
AIR ADVECTION INCREASING...ALSO EXPECT SCATTERED SHOWER AND
THUNDERSTORM ACTIVITY TO DEVELOP AHEAD OF THE LINE OF STORMS. LIKE
THE STORMS ALONG THE FRONT...THE STORMS AHEAD OF THE FRONT WILL
ALSO BE ELEVATED ABOVE THE COOLER SURFACE BOUNDARY LAYER.
HOWEVER...IT IS POSSIBLE THAT SOME OF THESE EARLY STORMS COULD
ALSO REACH SEVERE LIMITS...IN PARTICULAR SOUTH OF INTERSTATE 20
WHERE MUCAPE WILL BE HIGHER AND LAPSE RATES STEEPER.
HOWEVER...OVERALL THE INSTABILITY OVERNIGHT IT NOT THAT GREAT AND
THE ENVIRONMENT WILL LIKELY REMAIN CAPPED THROUGH MUCH OF THE
NIGHT.
THE GREATER SEVERE THREAT EXISTS WITH THE LINE OF STORMS DUE TO
SUFFICIENT INSTABILITY /MUCAPE VALUES OVER 500 J/KG /...STRONG WIND
SHEAR...AND BETTER LAPSE RATES. IN THIS PARTICULAR
ENVIRONMENT...LARGE HAIL WILL BE THE MAIN THREAT BUT DAMAGING
WINDS WILL ALSO BE POSSIBLE. CLOSER TO DAYBREAK...OR AROUND 6-7
AM...SOME OF THE MODELS DEVELOP SURFACE BASED CAPE UP TO 1000 J/KG
IN OUR SOUTHWESTERN AND SOUTHERN COUNTIES AS THE WARM FRONT LIFTS
INTO THAT AREA AND DEWPOINTS INCREASE INTO THE LOWER 60S. THE NAM
IS MOST AGGRESSIVE WITH THE SURFACE BASED CAPE BUT THE SITUATION
BEARS A CLOSE WATCH AS SURFACE BASED STORMS WILL POSE A TORNADO
THREAT IN THIS STRONGLY SHEARED ENVIRONMENT. WILL HIGHLIGHT A LOW
TORNADO THREAT THURSDAY MORNING ALONG AND SOUTH OF A LINE FROM
HAMILTON TO FAIRFIELD.
STRONG WEST WINDS WILL OCCUR BEHIND THE FRONT TOMORROW AFTERNOON
WHICH WILL RESULT IN TEMPERATURES RECOVERING INTO THE 60S AND
POSSIBLY LOWER 70S. A COLD FRONT WILL MOVE THROUGH THE REGION
THURSDAY NIGHT/EARLY FRIDAY MORNING. THIS WILL RESULT IN COOLER
TEMPS ON FRIDAY AND FREEZING TEMPS ACROSS MUCH OF THE REGION
FRIDAY NIGHT. ANOTHER SHORTWAVE AND UPPER LEVEL TROUGH WILL SWING
ACROSS THE REGION FRIDAY AND SATURDAY BUT THE MOISTURE WILL BE TOO
SCOURED OUT FOR ANY ADDITIONAL RAIN WITH THIS FEATURE. WE WILL
BRIEFLY WARM UP OVER THE WEEKEND BEFORE ANOTHER UPPER LEVEL SYSTEM
MOVES INTO THE PLAINS AND DRIVES A FRONT THROUGH THE REGION ON
MONDAY. SOUTHERLY RETURN FLOW AHEAD OF THIS SYSTEM MAY RESULT IN
SOME SHOWERS AND STORMS SUNDAY AND SUNDAY NIGHT.
82/JLD
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 42 65 33 54 32 / 70 100 5 5 0
WACO, TX 48 67 35 58 31 / 70 90 5 0 0
PARIS, TX 36 59 32 52 27 / 60 90 10 5 0
DENTON, TX 39 64 29 51 25 / 70 100 5 5 0
MCKINNEY, TX 38 64 30 52 28 / 70 100 5 5 0
DALLAS, TX 43 66 34 54 33 / 70 100 5 5 0
TERRELL, TX 41 64 34 55 30 / 60 100 5 5 0
CORSICANA, TX 46 67 37 59 32 / 60 90 10 5 0
TEMPLE, TX 48 69 36 62 33 / 80 90 5 0 0
MINERAL WELLS, TX 43 66 29 55 28 / 80 70 5 5 0
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
75/
AREA FORECAST DISCUSSION
NWS CORPUS CHRISTI TX
1042 PM CST WED FEB 20 2013
.DISCUSSION...SEE AVIATION DISCUSSION BELOW FOR THE 06Z TAF`S.
&&
.AVIATION...OVERALL THINKING REMAINS THE SAME WITH DRIER MID/UPPER
LEVELS MVG ACROSS THE AREA WHILE SHALLOW LOW LEVEL MOISTURE
REMAINS IN PLACE OVERNIGHT. THIS WILL LEAD TO PREVAILING MVFR
CIGS/VSBY`S AND IFR CIGS/VSBY`S BRIEFLY AT TIMES TOWARD EARLY THU
MORNING. VFR CONDITIONS ARE EXPECTED TO RESUME BY MID MORNING. A
FRONTAL BDRY IS STILL EXPECTED TO MOVE THROUGH S TX FROM THE NW TO
SE ON THU...LEADING TO MOD SLY WINDS TONIGHT SHIFTING TO THE SW
EARLY MORNING TO N BY EARLY AFTERNOON. LLWS IS EXPECTED OVERNIGHT
AS THE LLJ INCREASES TO 45-50KTS AND SFC WINDS DECREASE SLIGHTLY. WIND
SPEEDS ARE EXPECTED TO GRADUALLY DIMINISH THROUGH THU AFTERNOON.
&&
.PREV DISCUSSION... /ISSUED 941 PM CST WED FEB 20 2013/
DISCUSSION...LOWERED POPS A BIT OVER THE SOUTHERN AND WESTERN
AREAS...BUT KEPT THEM PRETTY MUCH THE SAME NORTHEAST AS
CONVERGENCE SHOWERS/STREAMERS STILL SEEM REASONABLE. ADJUSTED
CLOUDS A BIT FOR THIS EVENING. OTHERWISE SAW NO NEED TO MAKE ANY
CHANGES AT THIS TIME. TEMPERATURES ARE LOOKING GOOD AT THIS
TIME...EVEN THE HOURLY TEMPERATURES.
MARINE...DECIDED TO GO WITH A SCA FOR THE NORTHERN BAYS. IT WILL
BE CLOSE...BUT WILL FIT BETTER WITH SURROUNDING OFFICES. RUC13 AND
NAM12 ARE SHOWING WINDS GOING UP TO 20 KNOTS OR MORE OVER THAT
AREA SO WILL BITE ON THAT.
PREV DISCUSSION... /ISSUED 550 PM CST WED FEB 20 2013/
DISCUSSION...SEE AVIATION DISCUSSION BELOW FOR THE 00Z TAF`S.
AVIATION...DRIER MID/UPPER LEVELS WILL FILTER ACROSS S TX THROUGH
TONIGHT...HOWEVER LOW LEVEL MOISTURE WILL REMAIN IN PLACE THROUGH
MUCH OF THE NIGHT AHD OF A COLD FRONT. A SLY LOW LEVEL JET WILL
INCREASE TO 45-50KTS WHICH WILL LEAD TO A STRATUS DECK FLUCTUATING
BETWEEN 800-1500FT. PATCHY FOG IS ALSO POSSIBLE BRIEFLY AHD OF
THE FRONTAL BDRY TOWARD SUNRISE. ALI TO VCT MAY SEE THE VSBY DROP
TO AROUND 1SM AT TIMES. MOD TO STRONG S WINDS WILL CLOCK AROUND TO
THE SW AND W THROUGH EARLY TO MID MORNING BECOMING NW TO N BY LATE
MORNING INTO EARLY AFTERNOON AS THE BDRY MOVS ESE ACROSS THE AREA
ON THU. WINDS ARE EXPECTED TO DECREASE THROUGH THE AFTERNOON.
PREV DISCUSSION... /ISSUED 412 PM CST WED FEB 20 2013/
SHORT TERM (TONIGHT THROUGH THURSDAY NIGHT)...UPPER LEVEL
SHORT WAVE TROUGH WILL DEEPEN AND DEVELOP INTO CLOSED LOW AS IT
DIGS FROM SOUTHERN CA AND ACROSS THE TX PANHANDLE THROUGH THE
PERIOD. AS LOW PRESSURE DEEPENS OVER SOUTHWEST TEXAS...SOUTHEAST
WINDS WILL CONTINUE TO INCREASE ACROSS THE REGION TONIGHT.
ADDITIONALLY...A STRONG LLJ OF 40 TO 50KTS WILL DEVELOP OVER THE
EASTERN TWO THIRDS OF THE REGION THIS EVENING AND MOVE EASTWARD
ACROSS THE COASTAL WATERS TONIGHT. EXPECTING WINDS TO MIX TO THE
SURFACE...AND MODERATE TO STRONG ONSHORE FLOW TO DEVELOP ACROSS
THE WATERS. DUE TO THE ELEVATED WINDS AND WIDESPREAD CLOUD
COVER...KEPT MINIMUM TEMPERATURES ON THE WARMER SIDE TONIGHT.
THURSDAY A FRONTAL BOUNDARY WILL APPROACH FROM THE
NORTHWEST...ENTERING THE REGION BY NOON...AND STALL OFFSHORE
THURSDAY EVENING. DRY AIR WILL MOVE IN BEHIND THE FRONT AND
LOW TEMPERATURES WILL BE MUCH COOLER THAN THE NIGHT BEFORE. AS FOR
POPS...MODELS ARE NOW SHOWING MOST OF THE PRECIPITATION OCCURRING
TO THE NORTHEAST OF THE REGION. DID KEEP CHANCE POPS AROUND THE
VICTORIA CROSSROADS AND SLIGHT CHANCE ACROSS MUCH OF THE
REGION...BUT NOT EXPECTING TO GET MUCH OF ANYTHING WIDESPREAD.
LONG TERM (FRIDAY THROUGH WEDNESDAY)...THE EXTENDED FORECAST HAS
CHANGED LITTLE WITH THE 12Z MODEL RUNS. FRIDAY WILL BEGIN WITH HIGH
PRESSURE SURGING INTO THE REGION WITH DRIER AIR ADVECTING INTO SOUTH
TEXAS. WILL KEEP SLIGHT CHANCE TO LOW END CHANCE OF SHOWERS OVER THE
COASTAL WATERS FRIDAY MORNING WHERE LEFT OVER MOISTURE OVERRUN THE
STALLED FRONTAL BOUNDARY. TEMPERATURES WILL BE WARM DURING THE
AFTERNOON ON FRIDAY WITH THE LACK OF COLD AIR ADVECTION ASSOCIATED
WITH THE SURFACE HIGH PRESSURE. FRIDAY NIGHT INTO SATURDAY MORNING
WILL BE COOL...GENERALLY IN THE 40S AND 50S WITH WINDS BECOMING
LIGHT. THE SURFACE RIDGE IS PULLED EASTWARD AND MOVES AWAY FROM
SOUTH TEXAS WITH A WEAK RETURN FLOW DEVELOPING THROUGH THE WEEKEND.
THERE MAY BE ENOUGH MOISTURE RETURN ACROSS THE REGION FOR ISOLATED
SHOWERS AHEAD OF OUR NEXT BOUNDARY ON SUNDAY. A MID/UPPER LEVEL
TROUGH WILL SWEEP THROUGH THE CENTRAL PLAINS AND DRIVE THE FRONT
THROUGH SOUTH TEXAS MONDAY MORNING. THIS WILL ONCE AGAIN BRING
NORTHERLY WINDS AND DRIER CONDITIONS BACK ACROSS SOUTH TEXAS.
AGAIN...JUST A SLIGHT DROP IN AFTERNOON TEMPERATURES BEHIND THIS
BOUNDARY...WITH COOLER OVERNIGHT LOWS INTO TUESDAY MORNING. ONSHORE
FLOW RESUMES AGAIN TUESDAY INTO WEDNESDAY OF NEXT WEEK. OUR THIRD
FRONTAL BOUNDARY IN LINE WILL BE POSSIBLE IN THE MIDDLE OF THE NEXT
WEEK.
FIRE WEATHER...
A FRONTAL BOUNDARY APPROACHING FROM THE NORTHWEST TOMORROW WILL
BRING STRONG WINDS AND LOW RELATIVE HUMIDITIES TO THE RIO GRANDE
PLAINS AND BRUSH COUNTRY. NORTHWEST WINDS WILL RANGE FROM 15 TO
25 MPH WITH GUSTS UP TO 30 MPH AND MINIMUM RELATIVE HUMIDITY
VALUES WILL FALL BETWEEN 15 TO 20 PERCENT DURING THE AFTERNOON. THIS WILL
CREATE POSSIBLE CRITICAL FIRE WEATHER CONDITIONS FOR THE
AREA...AND A RED FLAG WARNING HAS BEEN ISSUED FOR THURSDAY FROM
9AM TO 3PM.
&&
.PRELIMINARY POINT TEMPS/POPS...
CORPUS CHRISTI 68 83 57 78 49 / 20 10 10 10 10
VICTORIA 64 79 50 71 43 / 40 40 10 10 10
LAREDO 65 84 51 79 52 / 10 10 10 0 0
ALICE 67 85 54 78 48 / 10 10 10 10 10
ROCKPORT 68 78 58 72 50 / 30 20 10 20 10
COTULLA 61 79 47 77 46 / 10 10 10 10 0
KINGSVILLE 66 85 53 78 47 / 10 10 10 10 10
NAVY CORPUS 68 81 60 75 54 / 20 10 20 10 10
&&
.CRP WATCHES/WARNINGS/ADVISORIES...
TX...RED FLAG WARNING FROM 9 AM TO 3 PM CST THURSDAY FOR THE
FOLLOWING ZONES: DUVAL...LA SALLE...MCMULLEN...WEBB.
GM...SMALL CRAFT ADVISORY UNTIL 3 PM CST THURSDAY FOR THE FOLLOWING
ZONES: COASTAL WATERS FROM BAFFIN BAY TO PORT ARANSAS OUT
20 NM...COASTAL WATERS FROM PORT ARANSAS TO MATAGORDA SHIP
CHANNEL OUT 20 NM...WATERS FROM BAFFIN BAY TO PORT ARANSAS
FROM 20 TO 60 NM...WATERS FROM PORT ARANSAS TO MATAGORDA
SHIP CHANNEL FROM 20 TO 60 NM.
SMALL CRAFT ADVISORY UNTIL 3 AM CST THURSDAY FOR THE FOLLOWING
ZONES: BAYS AND WATERWAYS FROM BAFFIN BAY TO PORT ARANSAS...
BAYS AND WATERWAYS FROM PORT ARANSAS TO PORT O`CONNOR.
&&
$$
TE/81...AVIATION
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1132 PM CST WED FEB 20 2013
.SHORT TERM...TONIGHT THROUGH SATURDAY
232 PM CST WED FEB 20 2013
FORECAST CONCERNS ARE ON WINTER STORM IMPACTING THE AREA THURSDAY
NIGHT INTO FRIDAY.
LATEST WATER VAPOR IMAGERY AND 500 MB RAP ANALYSIS SHOWED A COMPLEX
PATTERN ACROSS THE CONUS TODAY. AN UPPER LOW WAS LOCATED OVER NEW
ENGLAND WHILE ANOTHER WAS MOVING INTO SOUTHERN CALIFORNIA. AN UPPER
RIDGE EXTENDED FROM THE MID MISSISSIPPI RIVER VALLEY NORTH THROUGH
THE UPPER MIDWEST.
THE UPPER LOW OVER SOUTHERN CALIFORNIA WILL BE THE MAIN FEATURE TO
WATCH CLOSELY TONIGHT AS IT MOVES THROUGH ARIZONA AND NEW MEXICO
OVERNIGHT...EJECTING INTO THE CENTRAL PLAINS ON THURSDAY. THE LOW
WILL LIFT NORTHEAST THROUGH SOUTHEAST NEBRASKA EARLY FRIDAY EVENING.
AHEAD OF THE APPROACHING LOW...STRONG ISENTROPIC LIFT WILL MOVE
MOVE INTO THE FORECAST AREA ON THE 280-310 K SURFACES DURING THE
EVENING HOURS ON THURSDAY LEADING TO THE DEVELOPMENT OF SNOW.
IMPRESSIVE LIFT NOTED IN THE DENDRITIC GROWTH ZONE THURSDAY
EVENING INTO LATE THURSDAY NIGHT...WITH LIFT OF -20 UBAR/S NOTED
AT -15C. THE ONLY NEGATIVE WITH THIS SYSTEM IS THAT THE
INGREDIENTS FOR HEAVY SNOW FALL ADVECT NORTHEAST THROUGH THE
FORECAST AREA VERY QUICKLY DURING THE OVERNIGHT HOURS.
HOWEVER...MOST ARES WILL SEE A PERIOD OF HEAVY SNOWFALL WITH
ACCUMULATION RATES OF 1 TO 1.5 INCHES PER HOUR. SNOW ACCUMULATIONS
BY 12Z FRIDAY ARE EXPECTED TO RANGE FROM 5 TO 7 INCHES ACROSS MUCH
OF NORTHEAST IOWA. LOCATIONS OVER SOUTHEAST MINNESOTA AND
SOUTHWEST THROUGH CENTRAL WISCONSIN ARE EXPECTED TO SEE SNOW
ACCUMULATIONS OF 3 TO 6 INCHES. THE BULK OF THE SNOW WILL FALL
DURING THE OVERNIGHT HOURS THROUGH THE FRIDAY MORNING
COMMUTE...LEADING TO TRAVEL IMPACTS. HAVE ISSUED A WINTER STORM
WARNING FOR MOST OF NORTHEAST IOWA...EXCLUDING ALLAMAKEE
COUNTY...AND HAVE ISSUED A WINTER WEATHER ADVISORY FOR THE REST OF
THE FORECAST AREA. SEE WATCH/WARNING/ADVISORIES SECTIONS BELOW FOR
SPECIFIC TIMING. SNOWFALL AMOUNTS HAVE TRENDED SLIGHTLY LESS IN
THE 12Z GUIDANCE AND THIS MAKES SENSE GIVEN THE PROGRESSIVE NATURE
OF THE HEAVY SNOWFALL INGREDIENTS. THE LOW WILL LIFT NORTHEAST
DURING THE DAY ON FRIDAY AND IS EXPECTED TO BE LOCATED OVER SOUTH
CENTRAL MINNESOTA BY MIDDAY FRIDAY. LIGHT SNOW LOOKS TO PERSIST
INTO FRIDAY AFTERNOON WITH ADDITIONAL ACCUMULATIONS OF 1 TO 2
INCHES POSSIBLE. THE SNOW WILL TAPER OFF SOUTH AND WEST OF
INTERSTATE 94 THROUGH THE AFTERNOON HOURS AND PERSIST NORTH OF
I-94 INTO FRIDAY EVENING. WILL HAVE TO KEEP A CLOSE EYE ON
FREEZING DRIZZLE POTENTIAL OVER SOUTHWEST INTO CENTRAL WISCONSIN
AS ICE IS LOST ALOFT LATE FRIDAY MORNING INTO EARLY FRIDAY
AFTERNOON. OTHERWISE...HIGH PRESSURE WILL BE IN CONTROL TONIGHT
INTO THURSDAY MORNING PROVIDING COOL AND QUIET CONDITIONS. HIGH
CLOUDS WILL BE ON THE INCREASE FROM THE SOUTHWEST AHEAD OF THE
APPROACHING SYSTEM. LOOK FOR LOWS TONIGHT TO RANGE FROM THE SINGLE
DIGITS BELOW ZERO ACROSS NORTH CENTRAL WISCONSIN TO THE SINGLE
DIGITS ABOVE ZERO OVER NORTHEAST IOWA.
THE LOW WILL LIFT INTO UPPER MICHIGAN EARLY ON SATURDAY AS WEAK HIGH
PRESSURE BUILDS INTO THE FORECAST AREA. MOSTLY CLOUDY SKIES ARE
EXPECTED ACROSS THE FORECAST AREA ON SATURDAY UNDER THE INFLUENCE OF
WEAK CYCLONIC FLOW IN THE WAKE OF THE DEPARTING LOW. LIGHT SNOW
COULD LINGER ACROSS NORTH CENTRAL WISCONSIN DURING THE DAY. HIGHS ON
SATURDAY WILL RANGE FROM THE MID 20S OVER CENTRAL WISCONSIN TO THE
LOWER 20S OVER SOUTHEAST MINNESOTA. A VIGOROUS TROUGH WILL MOVE
THROUGH THE PACIFIC NORTHWEST ON SATURDAY...DIVING INTO THE CENTRAL
ROCKIES SATURDAY NIGHT. THIS SYSTEM IS THE NEXT FEATURE TO KEEP A
CLOSE EYE ON.
.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY
232 PM CST WED FEB 20 2013
20.12 MEDIUM RANGE MODELS ARE IN REASONABLE SATURDAY NIGHT THROUGH
SUNDAY SHOWING THE TROUGH PUSHING INTO THE CENTRAL ROCKIES BY SUNDAY
AFTERNOON. MEANWHILE...RIDGING WILL BUILD OVER THE UPPER MISSISSIPPI
RIVER VALLEY PROVIDING PARTLY SUNNY SKIES ON SUNDAY. HIGHS ON SUNDAY
ARE EXPECTED TO RANGE FROM THE LOWER 30S OVER CENTRAL WISCONSIN TO
THE UPPER 20S OVER NORTHEAST IOWA. THE TROUGH IS EXPECTED TO MOVE
EAST OUT OF THE ROCKIES AND INTO THE CENTRAL PLAINS AND DEEPENING
INTO A STRONG UPPER LOW. MODEL SOLUTIONS START TO DIVERGE SLIGHTLY
MONDAY INTO TUESDAY. THE 20.00 ECMWF TAKES THE LOW ACROSS EASTERN
KANSAS THROUGH NORTHERN MISSOURI MONDAY NIGHT AND INTO NORTHERN
ILLINOIS BY EARLY TUESDAY MORNING. THE GFS HAS A SLIGHTLY MORE
NORTHERLY TRACK. THIS SYSTEM WILL BRING WARMER AIR WITH IT AND THE
POTENTIAL FOR A RAIN AND SNOW MIX. THIS SYSTEM HAS THE POTENTIAL
TO BRING SIGNIFICANT SNOWFALL TO THE REGION BUT THE EXACT TRACK IS
UNCERTAIN AND WILL BE PINNED DOWN OVER THE NEXT FEW MODEL RUNS.
THE 20.00 ECMWF LIFTS THE LOW NORTH INTO EASTERN UPPER MICHIGAN BY
WEDNESDAY MORNING WHILE THE GFS TAKES IT TO THE EAST INTO THE OHIO
RIVER VALLEY. LIGHT SNOW CHANCES WILL CONTINUE TUESDAY INTO
WEDNESDAY...DEPENDING ON THE LOW TRACK.
&&
.AVIATION...THROUGH 06Z FRIDAY
1132 PM CST WED FEB 20 2013
VFR CONDITIONS WITH HIGH CLOUDS EXPECTED THROUGH 00Z FRIDAY WITH
WINDS GRADUALLY COMING AROUND TO THE EAST BUT REMAINING UNDER 10
KNOTS. BETWEEN 00Z-06Z SURFACE LOW BEGINS TO PUSH NORTHWARD OUT
OF THE CENTRAL PLAINS. QUESTION WILL BE ONSET OF SNOW AS SOUNDINGS
SHOW QUITE A BIT OF MID AND LOW LEVEL DRY AIR TO OVERCOME. MODELS
CONSISTENT IN SHOWING SNOW TO BREAK OUT BETWEEN 02Z-04Z AT BOTH
TAF SITES. ONCE THE SNOW BEGINS VISIBILITIES WILL QUICKLY LOWER
INTO THE IFR CATEGORY WITH CEILINGS LOWERING INTO THE IFR TO LOWER
MVFR CATEGORY.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
232 PM CST WED FEB 20 2013
WI...WINTER WEATHER ADVISORY FROM 6 PM THURSDAY TO 6 PM CST FRIDAY
FOR WIZ041-053>055-061.
WINTER WEATHER ADVISORY FROM MIDNIGHT THURSDAY NIGHT TO 6 PM CST
FRIDAY FOR WIZ017-029-032>034-042>044.
MN...WINTER WEATHER ADVISORY FROM 6 PM THURSDAY TO 6 PM CST FRIDAY
FOR MNZ079-086>088-094>096.
IA...WINTER STORM WARNING FROM 6 PM THURSDAY TO 6 PM CST FRIDAY FOR
IAZ008>010-018-019-029-030.
WINTER WEATHER ADVISORY FROM 6 PM THURSDAY TO 6 PM CST FRIDAY
FOR IAZ011.
&&
$$
SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION...RABERDING
AREA FORECAST DISCUSSION...UPDATE
NWS SAN DIEGO CA
525 AM PST THU FEB 21 2013
.SYNOPSIS...
A COOL NORTHERLY FLOW WILL CONTINUE ACROSS THE REGION INTO THE
WEEKEND. A WEAK DISTURBANCE MAY PRODUCE A FEW LIGHT SHOWERS TODAY
AND TONIGHT...OTHERWISE IT WILL BE PARTLY CLOUDY AND SLIGHTLY
WARMER. QUITE COOL AGAIN TONIGHT WITH PATCHY FROST POSSIBLE AGAIN IN
THE VALLEYS. GUSTY ONSHORE WIND SATURDAY WILL TURN OFFSHORE AND
BECOME GUSTY THROUGH AND BELOW PASSES AND CANYONS LATE SATURDAY
NIGHT AND SUNDAY AS ANOTHER UPPER-LEVEL TROUGH SLIDES SOUTHEAST
THROUGH THE GREAT BASIN. SEASONAL TEMPS AND DRY NEXT WEEK UNDER
NORTHWEST FLOW ALOFT.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
A FEW LOW CLOUDS WERE DEVELOPING EARLY THIS MORNING OVER COASTAL
AREAS...OTHERWISE SKIES WERE MOSTLY CLEAR. WINDS WERE MOSTLY
LIGHT...EXCEPT IN SOME MOUNTAIN AND DESERT AREAS WHERE THEY WERE
LOCALLY 15 TO 25 MPH.
AN UPPER-LEVEL HIGH WAS CENTERED OVER THE PACIFIC NEAR 160W...WHILE
A BROAD TROUGH COVERED THE WESTERN U.S. A SHORT-WAVE TROUGH WILL
DIVE SOUTH ACROSS CA TODAY...INCREASING CLOUDS AND BRINGING A CHANCE
FOR MORE LIGHT SNOW AND RAIN SHOWERS. BEST CHANCE FOR ACCUMULATIONS
WILL BE IN THE MOUNTAINS. THE WAVE IS WELL DEVELOPED ON WATER
VAPOR IMAGERY EARLY THIS MORNING NEAR THE NORTHERN CA BORDER. THIS
DISTURBANCE WILL EXIT THE REGION THIS EVENING...ALLOWING SKIES TO
CLEAR...SETTING US UP FOR ANOTHER CHILLY NIGHT.
ANOTHER...STRONGER WAVE WILL DIG SOUTH OVER THE WEEKEND. THIS ONE IS
WELL DEVELOPED ON SATELLITE IMAGERY NEAR THE BRITISH COLOMBIA COAST.
GLOBAL MODELS ALL DIG THE WAVE...BUT IT IS MOST AMPLIFIED ON THE 00Z
ECMWF/GEM MODELS. DEPENDING ON HOW STRONGLY IT DIGS...ONSHORE FLOW
MAY BECOME STRONG AND GUSTY OVER THE MTNS/DESERTS AGAIN ON SAT...
BEFORE TURNING BACK OFFSHORE AND BECOMING GUSTY THROUGH WND BELOW
THE OFFSHORE WIND PRONE PASSES AND CANYONS LATE SAT NIGHT AND SUN.
A DRY NW FLOW ALOFT AND MODERATING SURFACE FLOW SET THE STAGE FOR
FAIR AND SEASONAL WEATHER NEXT WEEK.
MAIN CONCERNS FOR THE NEXT FEW DAYS WILL BE THE CHANCE FOR SHOWERS
TODAY AND THIS EVENING...POSSIBLE FROST AGAIN TONIGHT...AND THE
UPCOMING ONSHORE...THEN OFFSHORE WINDS.
AT THIS TIME...WE WILL KEEP A CHANCE FOR SNOW/RAIN SHOWERS...MAINLY
SAN DIEGO COUNTY. 00Z ECMWF AND 06Z NAM BOTH SHOW SOME LIGHT
PRECIP...ALONG WITH THE LATEST HRRR MODEL...MAINLY IN SAN DIEGO
COUNTY TODAY.
IN TERMS OF FROST...HEIGHTS/THICKNESS DO INCREASE A BIT AND THERE IS
SOME WIND IN THE WAKE OF THE SHORT-WAVE. THE 4-KM NAM SHOWS SOME SFC
WARMING AS WELL...SO WOULD EXPECT FROST TO REMAIN PATCHY...AND IN
THE WIND-SHELTERED SPOTS.
BASED ON A BLEND OF GUIDANCE...EXPECT BOTH THE ONSHORE AND THE
OFFSHORE WINDS WILL BE AT OR BELOW ADVISORY STRENGTH IN THE WIND
PRONE FOOTHILL/MTN/DESERT AREAS...BUT WILL MONITOR. IF THE LATEST
RUNS OF THE ECMWF MODEL WERE TO VERIFY...THEY WOULD BE STRONGER.
BUT GIVEN THE ECMWF PERFORMANCE THIS SEASON WITH THESE SHORT-WAVES
IN NW FLOW...COULD WELL SEE SUBSEQUENT RUNS EASE OFF ON THIS MORE
WESTWARD TRACK.
&&
.AVIATION...
211000Z...A WEAK COASTAL EDDY WILL CONTINUE SCT-BKN LOW CLOUDS ALONG
THE COAST THROUGH THIS MORNING...WITH BASES AROUND 3000 FT MSL AND
TOPS TO 5000 FT MSL. PATCHY STRATUS WILL PENETRATE 25 TO 30 SM
INLAND BY MID THIS MORNING. SKC AND P6SM VIS ARE FORECAST THIS AFTN
THROUGH THE REMAINDER OF THE TAF PERIOD. ISOLATED SHOWERS POSSIBLE
THROUGH THIS EVENING BUT LITTLE AVIATION IMPACT EXPECTED.
&&
.MARINE...
THE SMALL CRAFT ADVISORY FOR THE OUTER COASTAL WATERS HAS BEEN
EXTENDED THROUGH 8 AM PST THIS MORNING DUE TO COMBINED SEAS
REMAINING ABOVE 10 FEET. SEAS WILL LOWER THROUGH THE MORNING AS THE
WIND CONTINUES TO DIMINISH.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 8 AM PST THURSDAY FOR THE OUTER
WATERS AND INCLUDING SAN CLEMENTE ISLAND.
&&
$$
PUBLIC...JAD
AVIATION/MARINE...JJT
AREA FORECAST DISCUSSION
NWS LINCOLN IL
532 AM CST THU FEB 21 2013
.DISCUSSION...
ISSUED 340 AM CST THU FEB 21 2013
WILL CONTINUE THE WINTER WEATHER ADVISORY ACROSS CENTRAL AND
SOUTHEAST IL BUT START IT AT NOON IN AREAS FROM SPRINGFIELD SW
AND START AT 3 PM REST OF CWA. WINTER WX ADVISORY GOES THROUGH 6
AM FRIDAY EXCEPT THROUGH NOON FRIDAY FROM LINCOLN NORTH. INCREASED
ICE ACCUMULATIONS OVER SE IL TO BETWEEN A TENTH AND A QUARTER INCH
AND ALSO ADDED ISOLATED THUNDERSTORMS TO SW AREAS LATE TODAY.
BRUNT OF SNOW STILL EXPECTED TO DEVELOP FROM SW TO NE DURING THE
AFTERNOON AND CONTINUE THIS EVENING BEFORE DIMINISHING OVERNIGHT.
SNOWFALL AMOUNTS TO RANGE FROM LESS THAN 1 INCH FROM I-70 SE TO
3-5 INCHES FROM I-55 NW WITH HIGHEST AMOUNTS NW OF THE IL RIVER.
BETWEEN 1 AND 3 INCHES OF SNOW OVER EAST CENTRAL IL WITH ICE
ACCUMULATIONS UP TO A TENTH INCH AS FAR NORTH AS I-72.
SHORT TERM...TODAY THROUGH SUNDAY
STRONG 541 DM 500 MB LOW NEAR THE SOUTHERN AZ/NM BORDER THAT
BROUGHT SNOW AS FAR SOUTH AS TUCSON IN SOUTHERN AZ THIS PAST NIGHT
HAS 996 MB LOW PRESSURE OVER NE NM. 1042 DM 500 MB ARCTIC HIGH
PRESSURE OVER NW ONTARIO AND RIDGING SOUTHWARD INTO IL AND TN VALLEY
BRINGING ANOTHER COLD NIGHT WITH TEMPS IN THE MID TO UPPER TEENS
CENTRAL IL AND LOWER 20S IN SE IL.
MODELS EJECT UPPER LEVEL LOW NE INTO THE CENTRAL PLAINS BY THIS
EVENING AND INTO WI FRI EVENING. STRONG SURFACE LOW IN NE NM TO
WEAKEN AS IT EJECTS NE INTO SE KS BY THIS EVENING AND INTO NW IL
BY MIDDAY FRI. MODELS HAVE TRENDED FURTHER SE WITH LOW PRESSURE
TRACK AND ALSO WITH COLDER AIR. MODELS IN GOOD AGREEMENT THAT MOST
OF CENTRAL/SE IL WILL STAY DRY THIS MORNING WITH SNOW SPREADING NE
ACROSS AREA DURING THE AFTERNOON THOUGH NOT TO AREAS NE OF I-74
UNTIL CLOSER TO 6 PM. SLEET MIXED IN WITH SNOW FROM I-72 SOUTH
WITH FREEZING RAIN POSSIBLE TOO IN SE IL ESPECIALLY LATER THIS
AFTERNOON. SPC HAS CHANCE OF THUNDERSTORMS FROM I-72 SOUTH THIS
AFTERNOON AND ADDED ISOLATED THUNDERSTORMS LATER THIS AFTERNOON TO
SW AREAS. THIS COULD ENHANCE SNOWFALL RATES OF 1-2 INCHES PER
HOURS IN A FEW CONVECTIVE BANDS THIS LATER THIS AFTERNOON AND
EARLY EVENING. USED A 10-12:1 SNOW RATIO FOR THIS EVENT PER BUFKIT.
MIXED PRECIPITATION TO GRADUALLY SPREAD NORTHWARD DURING TONIGHT
WITH AND DIMINISH TO FREEZING DRIZZLE DURING OVERNIGHT AS WE LOSE
MID LEVEL MOISTURE. AS STATED ABOVE...ICE ACCUMULATIONS UP TO A
TENTH INCH AS FAR NORTH AS I-72 WITH LESS THAN A TENTH INCH NORTH
OF I-72. BETWEEN A TENTH AND A QUARTER INCH OF ICE IN SOUTHEAST IL
FROM I-70 SOUTH WITH HIGHEST AMOUNTS FROM EFFINGHAM AND CLAY
COUNTY SW. SNOWFALL AMOUNTS LESS THAN 1 INCH FROM I-70 SE WHILE 3-5
INCHES FROM I-55 NW WITH HIGHEST AMOUNTS OF 4-6 INCHES NW BY KNOX...
FULTON AND SCHUYLER COUNTIES. SOME BLOWING SNOW POSSIBLE ESPECIALLY
NW AREAS WITH EAST WINDS INCREASING TO 15-20 MPH WITH GUSTS TO
AROUND 30 MPH THIS AFTERNOON AND EVENING.
LINGERING FREEZING DRIZZLE AND LIGHT SNOW FRIDAY NORTHERN AREAS
AND CONTINUE THE WINTER WX ADVISORY THROUGH NOON FRIDAY NORTH OF I-72.
SHOULD RISE ABOVE FREEZING FOR CENTRAL AND SE COUNTIES TO CHANGE
ANY LINGERING PRECIPITATION TO PATCHY DRIZZLE. WEAKENING UPPER
LEVEL LOW MOVES INTO MI SAT/SAT NIGHT WITH PRECIPITATION ENDING OVER
CENTRAL IL AND LOW CLOUDS DECREASING. TEMPS COOLING WITH HIGHS
AROUND 30F NORTH AND UPPER 30S IN SE IL SAT. DRY WEATHER CONTINUES
SUNDAY WITH TEMPS MODIFYING AS UPPER LEVEL RIDGE PUSHES EAST INTO
THE MS VALLEY AS WEAK SURFACE HIGH SETTLES OVER IL BY MIDDAY SUNDAY.
LONG TERM...SUNDAY NIGHT THROUGH WEDNESDAY
EXTENDED MODELS HAVE TRENDED A BIT COLDER WITH NEXT CUTOFF UPPER
LEVEL LOW EJECTING NE FROM THE SOUTHERN ROCKIES INTO IL BY TUE
MORNING. GFS APPEARS TOO FAST WITH THIS CUTOFF UPPER LEVEL LOW AND
TRENDED FORECASTER TOWARD SLOWER ECMWF. BEST CHANCES OF
PRECIPITATION LATER MONDAY INTO TUESDAY. MAINLY RAIN OVER SE IL
WHILE MIX OF RAIN/SNOW OVER CENTRAL IL. UPPER LEVEL LOW TO LINGER
OVER THE GREAT LAKES REGION MIDDLE OF NEXT WEEK AND COULD KEEP
CLOUDS AROUND LONGER ALONG WITH LOW CHANCES OF LIGHT PRECIPITATION
ESPECIALLY NE AREAS. STUCK CLOSE TO ALLBLEND TEMPS DURING THIS
TIME WHICH IS CLOSE TO NORMAL FOR LATE FEBRUARY.
07
&&
.AVIATION...
ISSUED 532 AM CST THU FEB 21 2013
LARGE STRATOCUMULUS DECK AROUND 2000 FEET IS ADVECTING IN FROM THE
NORTHEAST...WITH AWIPS TIMING TOOLS INDICATING ARRIVAL FROM KBMI-
KCMI BY AROUND 13Z. RAP MODEL HUMIDITY PLOT AT 2500 FEET LINES UP
WELL...AND SUGGESTS IT SHOULD CONTINUE TOWARD KPIA AND KDEC TOWARD
16-17Z. WILL KEEP THESE MVFR CEILINGS OUT OF KSPI FOR NOW...BUT
CONDITIONS THERE WILL RAPIDLY DETERIORATE EARLY THIS AFTERNOON
WITH SNOW MOVING IN FROM THE SOUTHWEST TOWARD 21Z. THIS
PRECIPITATION WILL OVERSPREAD THE REMAINING TAF SITES BY ABOUT
23Z...WITH IFR OR LIFR CONDITIONS BECOMING WIDESPREAD. FORECAST
SOUNDINGS SHOWING SOME FREEZING RAIN POTENTIAL AT KSPI/KDEC EARLY
THIS EVENING AS WELL. HEAVIEST PRECIPITATION EXPECTED THROUGH
ABOUT 04-05Z...WITH A GRADUAL TREND TOWARD FREEZING DRIZZLE AT ALL
TAF SITES AFTER 06Z.
GEELHART
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 6 AM CST
FRIDAY FOR ILZ043>046-053>057-061>063-066>068-071>073.
WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO NOON CST
FRIDAY FOR ILZ027>031-036>038-041-042.
WINTER WEATHER ADVISORY FROM NOON TODAY TO 6 AM CST FRIDAY FOR
ILZ040-047>052.
&&
$$
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
548 AM CST THU FEB 21 2013
.UPDATE...FOR 12Z AVIATION DISCUSSION BELOW
&&
.DISCUSSION.../ISSUED 404 AM CST THU FEB 21 2013/
TWO WEATHER CONCERNS COMING UP IN THE NEXT WEEK. FIRST WILL BE
SNOW FROM THURSDAY NIGHT THROUGH FRIDAY NIGHT...WITH ANOTHER
POTENTIAL SNOW MAKER FOR NEXT WEEK. MODEL AGREEMENT REMAINS HIGH
WITH THE FIRST SYSTEM...BUT THERE REMAINS QUITE A BIT OF SPREAD
WITH SYSTEM TWO...ESPECIALLY IN TERMS OF TIMING.
OUR FIRST WAVE IS EASILY IDENTIFIABLE THIS MORNING ON WATER VAPOR
IMAGERY THIS NEAR ALBUQUERQUE...WITH AN IMPRESSIVE CLUSTER OF
THUNDERSTORMS MOVING NORTH OUT OF OK THAT IS ON THE NOSE OF 90 KT
MID LEVEL JET ROUNDING THE BASE OF THE TROUGH. UP HERE...THE MPX
AREA REMAINS UNDER THE INFLUENCE OF A 1040 MB ARCTIC HIGH CENTERED
OVER NW ONTARIO...WITH A RIDGE AXIS DOWN THE ST. CROIX/MIS RIVER
VALLEYS. THIS HIGH IS THE SOURCE FOR OUR LOW LEVEL AIR...WITH
DEWPS HOVERING AROUND ZERO AS A RESULT. TEMPERATURES ARE ALSO A
FEW DEGREES ON EITHER SIDE OF ZERO AND HAVE BEEN HELD IN CHECK BY
A THIN BLANKET OF CIRRUS. FOR TODAY...THE HIGH WILL KEEP ANY
PRECIP SOUTH OF THE MPX CWA...WITH THICKENING HIGH CLOUDS HELPING
TO KEEP TEMPERATURES A LITTLE BIT MORE UNIFORM THAN WHAT WAS SEEN
YESTERDAY.
FOR US...THE HEAVY SHIELD OF PRECIP MOVING ACROSS SRN KANSAS WILL
BE WHAT BRINGS THIS REGION MOST OF ITS SNOW. AT 3AM...THIS PRECIP
WAS STILL ALL SOUTH OF I-70...SO IT WILL BE A WHILE BEFORE
REACHING THE I-90 CORRIDOR. MODELS HAVE MAINTAINED GOOD AGREEMENT
WITH THEIR HANDLING OF THE SYSTEM...WITH THE ONE OUTLIER
CONTINUING TO BE THE NAM...WHICH IS STILL RUNNING A BIT HIGHER
WITH QPF ACROSS MN/WRN WI...THOUGH IT HAS COME DOWN MORE IN LINE
WITH THE ECMWF/GFS/SREF/GEM. FOR TIMING PRECIP WITH THIS SYSTEM...
FAVORED THE SREF TIMING AS IT IS BASICALLY IN LINE WITH EVERYTHING
ELSE AND DOES ACCOUNT FOR SOME MINIMAL SPREAD. FOR QPF...A BLEND
OF THE ECMWF/GFS/SREF WAS USED...ALONG WITH SNOW RATIOS OF
15-16:1.
SO WHAT CHANGED? FIRST...SLOWED EVEN FURTHER HOW QUICKLY THINGS
MOVE NORTH TONIGHT...WITH NO CATEGORICAL POPS IN THE SOUTH UNTIL
AFTER 3Z AND DELAYING THE START OF SNOW ACROSS THE FAR NRN CWA
UNTIL AFTER 9Z. QPF/SNOWFALL WITH THIS FORECAST HAD ONLY A SLIGHT
NUDGE DOWN IN BOTH. CURRENT GRIDS HAVE 4-5 INCHES ALONG AND SOUTH
OF A ST. JAMES...TO MANKATO...TO RICE LAKE LINE. 3 TO 4 INCHES ARE
CURRENTLY INDICATED NORTHWEST TO A REDWOOD FALLS...TO
MONTICELLO...TO CAMBRIDGE LINE...WHICH IS BASICALLY AS FAR NW AS
CURRENT ADVISORY GOES...SO NO AREAL EXPANSIONS WERE NEEDED WITH IT
TONIGHT. PART OF THE REASON TOTALS ARE AS HIGH AS THEY ARE IS THAT
AS THIS SYSTEM SLOWLY FILLS FRIDAY INTO SATURDAY...LIGHT SNOW WILL
PERSIST ACROSS MUCH OF THE AREA RIGHT THROUGH FRIDAY
NIGHT...HELPING BOOST SNOW TOTALS SOME...ESPECIALLY ACROSS WRN WI.
LEFT STARTING/END TIMES UNCHANGED WITH ADVY...BUT WITH SNOW LIKELY
TO PERSIST THROUGH FRIDAY NIGHT...EXTENDING THE ADVISORY INTO
SATURDAY MORNING ACROSS ERN AREAS WILL BE SOMETHING FUTURE SHIFTS
WILL NEED TO THINK ABOUT.
MODELS SHOW SNOW FINALLY CUTTING OFF DURING THE DAY SATURDAY AS
UPPER LOW BEGINS TO EJECT EAST ACROSS THE GREAT LAKES...ALLOWING
SFC RIDGE TO MOVE IN. GOOD NEWS THOUGH IS WE WILL NOT SEE A GOOD
PUNCH OF ARCTIC AIR BEHIND THIS SYSTEM...SO WILL MAINTAIN HIGHS IN
THE 20S/30S INTO THE WEEKEND.
NEXT SYSTEM TO POTENTIALLY IMPACT THE AREA DURING THE FIRST HALF
OF NEXT WEEK CAN BE FOUND OUT IN THE FAR WEST END OF THE ALEUTIAN
ISLAND CHAIN AT THE MOMENT. STILL SEE A DECENT AMOUNT OF SPREAD
WITH THIS SYSTEM...WITH THE GFS PUSHING SNOW IN BY SUNDAY
NIGHT...WHILE THE ECMWF/GEM DO NOT REALLY BRING ANYTHING IN UNTIL
TUESDAY. THE GEFS MEAN LOOKS SIMILAR TO THE GFS...WITH THE FIM
HAVING TIMING MORE IN LINE WITH THE GEM/ECMWF...BUT TAKES THE
SYSTEM WELL SOUTHEAST OF MN/WRN WI. GIVEN ALL THE SPREAD IN
TIMING...MODEL BLEND USED IN THE EXTENDED PORTION OF THIS
FORECAST WOUND UP PLASTERING CHANCE POPS FROM SUNDAY NIGHT THROUGH
TUESDAY. THIS SECOND SYSTEM DOES LOOK SOMEWHAT SIMILAR TO WHAT THE
FIRST STORM WILL BE LIKE...WITH AN OCCLUDED AND FILLING IN LOW
MOVING NORTH OUT OF THE SOUTHERN PLAINS...RESULTING IN HIGHEST
PRECIP AMOUNTS SOUTH OF THE AREA. ONE DIFFERENCE THOUGH BETWEEN
NEXT WEEKS SYSTEM AND THIS WEEKS IS THAT TEMPS WILL BE RUNNING 5
TO 10 DEGREES WARMER NEXT WEEK...THOUGH SHOULD STILL BE JUST COLD
ENOUGH IN THE EAST TO KEEP THINGS AS ALL SNOW.
&&
.AVIATION.../12Z TAF ISSUANCE/
SQUEEZE PLAY FOR THE LOW CLOUDS TODAY...WITH MVFR/IFR CLOUDS
LIFTING NORTHEAST FROM KS/NE...AND STRATUS OOZING SOUTHWEST FROM
LAKE SUPERIOR AND THE UP OF MI. EXPECT THE SOUTHERN BATCH TO
SPREAD FROM SOUTHERN MN TO REACH KRWF-KAXN-KSTC BETWEEN 03Z AND 09Z
FRIDAY...WITH EASTERN SITES /KEAU-KRNH-KMSP/ LIKELY SEEING LOW
CLOUDS ARRIVE EARLIER THIS AFTERNOON. BASED UPON CURRENT SATELLITE
IMAGERY AND HRRR/RAP MODELS...HAVE INTRODUCED A SCT-BKN MVFR CLOUD
LEVEL BETWEEN 17Z AND 20Z AT KEAU-KRNH-KMSP...BECOMING OVERCAST
BETWEEN 21Z THURSDAY AND 00Z FRIDAY. SNOW IS EXPECTED TO BLOSSOM
OVER THE AREA AFTER 05Z FRIDAY...WITH IFR VSBYS AND MVFR CIGS BECOMING
COMMON THROUGH FRIDAY MORNING. WINDS FROM 050-090 DEGREES WILL
PREVAIL...MAINLY FROM 5 TO 10 KTS.
KMSP...
SCT CLOUDS AROUND 2500 FT MAY MOVE INTO THE AIRPORT FROM THE
NORTHEAST THIS AFTERNOON. PER HRRR AND RAP SOLUTIONS...INTRODUCED
A 21Z SCT MVFR CLOUD GROUP...WITH OVC CIGS ARRIVING AROUND 00Z.
STILL EXPECT SNOW TO HOLD OFF UNTIL AFTER 05Z...AS WE/LL STILL BE
WAITING ON THE FORCING/DYNAMICS TO ARRIVE FROM THE SOUTHWEST.
THE TIME FRAME FOR THE WORST CONDITIONS STILL LOOKS TO BE BETWEEN 08Z
AND 12Z...WHEN VSBYS BETWEEN 1/2SM AND 1 SM ARE EXPECTED. WINDS
BETWEEN 080-090 WILL PREVAIL TODAY...WITH 050-070 FOR TONIGHT.
SPEEDS BETWEEN 6 KTS AND 10 KTS ARE EXPECTED THROUGH THE PERIOD.
/OUTLOOK FOR KMSP/
FRI NIGHT...IFR CIGS AND VSBY EXPECTED...WITH
-SN LIKELY. NE WIND 5-15 KT...BECOMING NW LATE.
SAT...MVFR CIGS WITH -SN IN THE MORNING. W WIND 5 KT.
SUN...VFR CIGS EARLY...MVFR CIGS LATE. CHANCE -SN LATE. SE WINDS
BECOMING NE 5 KT.
MON...MVFR CIGS WITH CHANCE -SN. NE WINDS 5 TO 10 KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST
FRIDAY FOR BLUE EARTH-BROWN-CARVER-DAKOTA-FARIBAULT-
FREEBORN-GOODHUE-HENNEPIN-LE SUEUR-MARTIN-MCLEOD-NICOLLET-
REDWOOD-RENVILLE-RICE-SCOTT-SIBLEY-STEELE-WASECA-WATONWAN-
WRIGHT.
WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM CST FRIDAY
FOR ANOKA-CHISAGO-RAMSEY-WASHINGTON.
WI...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM CST FRIDAY
FOR BARRON-CHIPPEWA-DUNN-EAU CLAIRE-PEPIN-PIERCE-POLK-RUSK-
ST. CROIX.
&&
$$
MPG/LS
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
530 AM CST Thu Feb 21 2013
...UPDATED AVIATION DISCUSSION...
.DISCUSSION...
Intense winter storm is taking direct aim on the forecast area this
morning. Overnight model runs...including the near-term RAP and
HRRR models...now indicate a broad swath of 1"+ liquid-equivalent
precipitation totals overspreading most of the forecast area with the
heaviest axis centered very close to Kansas City. How these precip
totals translate into snow and sleet amounts is still somewhat of a
question mark given the presence of warm air in the 800-700 hPa layer
and a shallow depth of the max dendritic growth region. Seems most
methods are giving snow to liquid ratios on the order of 8:1 to 10:1
near I-70...and around 10:1 to 12:1 north of Highway 36. Applying
these ratios to expected precip totals now results in a broad swath
of 8 to 12 inch snows forecast for most of the forecast
area...generally along and north of a Paola...Marshall...Moberly
line. These areas are unlikely to see much if any sleet
contamination and could see some totals approach or exceed February
records (see climate section below). Still expect sleet to fall across
areas south of this line, and there could be a good deal of it.
Exactly how much sleet falls across these areas will have huge
impacts on snow amounts, which could be as low as 3 or 4 inches if
sleet lasts several hours...to as much as 8 to 10 inches if sleet is
only brief. Freezing rain still appears a possibility for the
Clinton/Sedalia/Boonville areas but any icing should be limited to a
tenth of an inch or less.
Looking upstream, synoptic and mesoscale ascent has become quite
strong and is coupled throughout a large depth of the atmosphere.
Combine this with strong moisture advection from the south, the
result has been an expanding area of heavy precipitation over
northern OK and southern KS with several bands of convection feeding
into it. In fact, lightning profilers have lit up vividly down there,
even in the stratiform precipitation over KS, suggestive of quite a
bit of slantwise and even upright instability. This instability will
spread into ern KS/wrn MO through the morning and could easily
result in occasional thunder and snowfall rates of 2" to 3" per hour.
Heaviest precipitation band will spread into northern MO through the
afternoon and taper off across the KC area by 21Z or so. However,
broad synoptic scale and weak deformation forcing will continue well
into the evening and overnight as the upper low moves overhead. This
could result in an extra 2" to 5" of snow from late afternoon into
the early morning hours particularly north of the Missouri River.
Hawblitzel
Friday and Saturday...
As the system departs, a few lingering snow showers may be possible
across far northeast Missouri, but little to no additional snow
accumulation is expected. Temperatures will have difficulty rising
much on Friday with widespread snow cover and colder air advecting
into the region, so have kept high temperatures only a few degrees
warmer than Thursday night lows. Frigid temperatures are possible
Friday night as surface high pressure drifts over western Missouri,
combining the residual snow cover with light winds and clear skies.
Warmer air will begin to build into the region on Saturday as the
upper low departs, but reaching highs much above freezing will be
difficult, especially without strong return flow at low levels.
Sunday and Monday...
Another deep trough axis will swing through the four corners region
on Sunday, bringing a deepening surface low into the southern High
Plains by early Monday. This system is currently projected to lift
northeast into the region on Monday afternoon, taking a somewhat
similar track to the current system; however, there is still a good
deal of uncertainty in this forecast. Moisture may be a bit more
limited with a smaller window of time to draw from the Gulf, and
this more southern track is a very recent trend with the 00z models,
so for now have kept probabilities relatively low and maintained a
rain or snow precipitation type to cover several possible scenarios.
Tuesday through Thursday...
Quieter conditions should prevail for the remainder of next week as
a more persistent ridge builds over the west. A few snow showers may
be possible Tuesday night into early Wednesday as a weak clipper
dives in behind the departing upper low, but any snowfall that does
occur should be fairly light, and the probability of measurable snow
is low. Temperatures will remain below normal as a result of cold
air wrapping behind the upper low and additional cold air dropping
southeast with the clipper, but should eventually recover when the
ridge over the Rockies begins to shift east.
Laflin
&&
.CLIMATE...
The last time Kansas City officially measured 12" of snow was
January 18-19 in 1962 (14.0"). The most recent snowfall greater than
10" was February 24-25 in 1993 (11.1").
Top 10 snowfalls for Kansas City
1. 24.2"...Mar 22-24 1912
2. 15.8"...Feb 11-12 1894
3. 14.6"...Jan 20-21 1958
4. 14.0"...Jan 18-19 1962
5. 13.8"...Mar 14-15 1960
6. 13.7"...Jan 8-9 1930
7. 13.0"...Feb 27-28 1900
8. 12.3"...Mar 29-31 1926
9. 12.2"...Dec 23-24 1918
10. 11.9"...Mar 3-5 1915
Top 5 daily February snowfalls for Kansas City
1. 11.8"...27th 1900
2. 10.5"...4th 1915
3. 8.7"...23rd 1990
4. 8.6"...2nd 1960
5. 8.0"...15th 1960
&&
.AVIATION...
For the 12Z TAFs...major winter storm will impact all terminals for
much of the day with very heavy snow rates of 1 to 2 inches per hour,
possibly more. Occasional lightning is also possible. This activity
is right on the doorstep, so will go ahead and introduce heavy snow
to the KC and STJ terminals right at the onset of the TAF period. The
heavy nature of the snow is likely to bring every airport below
operational minimums at times. Heaviest snow will gradually taper
off across KC/STJ by mid afternoon, and across central and northeast
MO late afternoon. However, additional light snow through the evening
could produce additional light accumulations and prolonged IFR
conditions through the night.
Hawblitzel
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER STORM WARNING until Midnight CST tonight FOR MOZ039-040-
045-046.
WINTER STORM WARNING until Midnight CST tonight FOR MOZ028>030-
037-038-043-044-053-054.
WINTER STORM WARNING until 6 AM CST Friday FOR MOZ001>004-
011>013-020-021.
WINTER STORM WARNING until 6 AM CST Friday FOR MOZ005>008-
014>017-022>025-031>033.
KS...WINTER STORM WARNING until Midnight CST tonight FOR KSZ057-060-
103>105.
WINTER STORM WARNING until 6 AM CST Friday FOR KSZ025-102.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
950 AM CST THU FEB 21 2013
.DISCUSSION...
FORECAST CHALLENGE FOR UPDATE CONCERNS CLOUD TRENDS AND
TEMPERATURES. SEVERAL CLOUD AREAS TO POTENTIALLY AFFECT FA TODAY.
VFR CIGS CONTINUE TO LIFT NORTH THROUGH FAR WESTERN FA. ALSO SOME
WEAK RETURNS FROM KMVX-88D OVER DVL BASIN HOWEVER METARS SO FAR
REPORTING NO PCPN AND RETURNS LIKELY PICKING UP ON CIGS. WITH
NEAREST MEASURABLE SNOW FROM BIS-MOT WILL JUST MENTION FLURRIES
REMAINDER OF AM. CI SHIELD FROM CENTRAL PLAINS STORM LIFTING N
AROUND 35KTS AND CURRENT TRENDS WOULD HAVE MOST OF FA AFFECTED BY CI
BY EARLY AFTERNOON. STILL NOT MUCH CONFIDENCE ON DEGREE OF WESTWARD
ADVANCE OF STRATUS COMING OFF OF LAKE SUPERIOR AND WILL CONTINUE TO
MONITOR FOR AVIATION PURPOSES. WITH FILTERED SOLAR AFFECTING MOST
AREAS FEEL CURRENT TEMPERATURES IN LINE SO WILL BE MAKING MINIMAL
CHANGES. WILL MAKE THE POP AND CLOUD TREND ADJUSTMENTS WITH THE
REMAINDER OF THE FORECAST OK.
&&
.AVIATION...
EXPECT VFR CONDITIONS WITH SOME LOWER VFR CIGS NEAR KDVL FOR TODAY.
WILL NEED TO MONITOR THE POTENTIAL FOR LOWER CIGS ADVECTING INTO THE
REGION FROM THE EAST THIS AFTERNOON. 12Z RAP INDICATES LOWER CIGS
ACROSS NORTHEAST MINNESOTA WILL EXPAND WESTWARD...AND OBSERVATIONS
HAVE SHOWN SOME WESTWARD MOVEMENT OF THE LOWER CIGS. WILL AT LEAST
HINT AT A LOWER CLOUD DECK FOR KBJI THIS AFTERNOON IN THE TAF.
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
VOELKER/JAM
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
921 AM CST THU FEB 21 2013
.SHORT TERM...TODAY
921 AM CST THU FEB 21 2013
QUICK UPDATE TO THE FORECAST TO ACCOUNT FOR STRATUS DECK THAT HAS
FORMED ACROSS CENTRAL AND EASTERN WISCONSIN THIS MORNING. THIS
HAS NOW PUSHED WEST INTO THE FORECAST AREA...AND 21.12Z NAM AND
21.13Z RAP CAPTURE THE LOW LEVEL SATURATION VERY WELL...BRINGING
IT AROUND THE MISSISSIPPI RIVER IN THE LATE MORNING...THEN ACROSS
MOST OF THE AREA BY EARLY AFTERNOON. THE SATURATION IS OCCURRING
IN THE DENDRITIC GROWTH ZONE GIVEN THE COLD TEMPERATURES THIS
MORNING SO LIGHT SNOW / FLURRIES ARE BEING REPORTED AS WELL. THIS
WILL PERSIST FOR MUCH OF THE LATE MORNING AND AFTERNOON HOURS.
VISIBILITY REDUCTIONS HAVE BEEN AS LOW AS 2 MILES...BUT MAINLY IN
THE 4 TO 6 MILE RANGE.
.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY
303 AM CST THU FEB 21 2013
21.00Z GFS/ECMWF SHOW A RIDGE OF HIGH PRESSURE DRIFTING ACROSS THE
REGION SATURDAY NIGHT THROUGH SUNDAY FOR A BRIEF DRY/QUIET PERIOD.
LOWS SATURDAY NIGHT ARE EXPECTED TO DROP INTO THE SINGLE
DIGITS/LOWER TEENS ABOVE ZERO WITH HIGHS ON SUNDAY RIGHT AROUND
NORMAL IN THE MIDDLE 20S TO LOWER 30S. ATTENTION THEN TURNS TO THE
NEXT STORM SYSTEM TO AFFECT THE AREA SUNDAY NIGHT THROUGH
WEDNESDAY. THIS SYSTEM LOOKS LIKE IT WILL GIVE THE AREA ANOTHER
SHOT OF LONG DURATION ACCUMULATING SNOW WITH PERHAPS A MIX OF
RAIN/SNOW IN THE SOUTH DURING THE DAY MON/TUE AS SURFACE
TEMPERATURES WARM A DEGREE OR TWO ABOVE THE FREEZING MARK. MODELS
PRETTY CLOSE...BUT STILL A BIT AT ODDS WITH THE EXACT TRACK OF THE
LOW. THIS WILL OF COURSE DETERMINE THE EXACT OUTCOME OF ACCUMULATING
SNOW AMOUNTS...DEFINITELY SOMETHING TO KEEP AN EYE ON.
&&
.AVIATION...TODAY AND TONIGHT
515 AM CST THU FEB 21 2013
VFR CONDITIONS WILL PREVAIL THROUGH THE LATE AFTERNOON AS HIGH
PRESSURE SLOWLY DRIFTS AWAY FROM THE REGION. A WINTER STORM
ADVANCING NORTHEAST OUT OF THE SOUTHERN PLAINS STATES WILL BRING A
ROUND OF SNOW TO THE AREA TONIGHT. PLENTY OF FORCING WITH THIS
SYSTEM WITH THE 21.06Z NAM SHOWING UP TO 30 PVU/S OF VORTICITY
ADVECTION IN THE 500-300 MB LAYER AND A COUPLE BANDS OF WEAK TO
MODERATE FRONTOGENESIS IN THE 850-500 MB LAYER. THE HIGH PRESSURE
WILL LEAVE PLENTY OF DRY AIR IN PLACE WITH CONDENSATION PRESSURE
DEFICITS OF 200+ MB ON THE 280K ISENTROPIC SURFACE. THE INITIAL UP
GLIDE OF 2 TO 5 UBAR/S WILL GO INTO SATURATING THIS DRY LAYER WITH
TOTAL SATURATION EXPECTED TO OCCUR AT THE TAF SITES BETWEEN 22.03Z
AND 22.06Z. INTERESTING TO NOTE THAT THE NAM BUFKIT SOUNDINGS FOR
BOTH SITES SHOWS A MVFR DECK DEVELOPING EARLY IN THE EVENING AS
THE DRY AIR BECOMES CONFINED TO THE 900-700 MB LAYER. LOOKING DOWN
STREAM INTO KANSAS...THERE IS A MVFR DECK WELL OUT AHEAD OF THE
MAIN PRECIPITATION SHIELD SO HAVE INCLUDED THIS. EXPECTING LIGHT
SNOW WITH MVFR VISIBILITIES TO DEVELOP DURING THE MID EVENING AND
ONCE THE COLUMN TOTALLY SATURATES UP...THE VISIBILITY AND CEILINGS
WILL GO DOWN TO IFR AND THEN STAY THERE OVERNIGHT.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
303 AM CST THU FEB 21 2013
WI...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST
FRIDAY FOR WIZ041-053>055-061.
WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM CST
FRIDAY FOR WIZ017-029-032>034-042>044.
MN...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST
FRIDAY FOR MNZ079-086>088-094>096.
IA...WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 PM CST FRIDAY
FOR IAZ008>010-018-019-029-030.
WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST FRIDAY
FOR IAZ011.
&&
$$
SHORT TERM...ZT
LONG TERM...DAS
AVIATION...04
AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
930 AM PST THU FEB 21 2013
.SYNOPSIS...
NORTHERLY FLOW ALOFT WILL CONTINUE ACROSS THE REGION THROUGH
SATURDAY AND RESULT IN ONLY A SLIGHT WARMING TREND. A WEAK
DISTURBANCE WILL PRODUCE SCATTERED LIGHT SHOWERS TODAY INTO THIS
EVENING...WITH SHOWERS MOST COMMON IN THE MOUNTAINS. PATCHY FROST IS
EXPECTED IN THE VALLEYS TONIGHT. GUSTY WESTERLY WINDS ARE EXPECTED
IN THE MOUNTAINS AND DESERTS SATURDAY...THEN STRONGER NORTHEAST
WINDS WILL DEVELOP THROUGH AND BELOW PASSES AND CANYONS LATE
SATURDAY NIGHT AND SUNDAY AS ANOTHER UPPER-LEVEL TROUGH OF LOW
PRESSURE SLIDES SOUTHEAST THROUGH THE GREAT BASIN. MOSTLY SEASONAL
TEMPERATURES ARE EXPECTED EARLY NEXT WEEK UNDER NORTHWEST FLOW.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
A FEW SHOWERS WERE OCCURRING THIS MORNING AHEAD OF A SHORTWAVE
MOVING SOUTHEAST THROUGH CENTRAL CALIFORNIA. SOME DENSE FOG WAS
OCCURRING OVER THE MOUNTAINS WHERE THE CLOUDS WERE INTERSECTING THE
TERRAIN...MOSTLY ABOVE 4000 FEET ABOVE SEA LEVEL. EXPECT SOME MORE
SHOWERS TODAY AS HIGH-RES MODELS SUCH AS THE HRRR AND LOCAL WRF ARE
SHOWING SCATTERED LIGHT PRECIP AND MODERATELY HIGH RH MOSTLY BELOW
700 MB. SNOW LEVELS WILL BE RISING TO ABOUT 5000 FEET DURING THE
AFTERNOON. PRECIP SHOULD END NORTH TO SOUTH LATE TODAY/EARLY THIS
EVENING...AND MOST AREAS SHOULD CLEAR BY LATE TONIGHT. WHILE LOCALLY
GUSTY WINDS ARE PROGGED THROUGH/BELOW N-S/NE-SW ORIENTED
PASSES/CANYONS SUCH AS CAJON PASS AND IN THE SANTA ANA MTNS
TONIGHT/EARLY FRI...GUST POTENTIAL IS AROUND 40 MPH AT 12Z/4
AM...AND MOSTLY AT HIGHER ELEVATIONS...SO NO WIND ADVISORY WILL BE
ISSUED. A FROST ADVISORY MIGHT BE NEEDED IN THE VALLEYS TONIGHT AS
MOST VALLEY FLOORS WILL HAVE LITTLE/NO WIND AND CLEAR SKIES UNDER
THE COLD AIR MASS WITH 850 MB TEMPS STILL AROUND 3-4 DEG C. WILL
EVALUATE FOR THE AFTERNOON PACKAGE.
N/NW FLOW ALOFT WILL CONTINUE THROUGH SATURDAY AND RESULT IN ONLY A
SLOW WARMING TREND...WITH TEMPS REMAINING BELOW NORMAL. A GULF OF
ALASKA TROUGH WILL MOVE THROUGH THE PAC NW FRI NIGHT AND THROUGH
UTAH SAT NIGHT. TEMP GRADIENTS WILL INCREASE IN THE 850-700 MB
LAYER...AND 12Z NAM SHOWS 40-KNOT WINDS AT 850 MB...DOWN A BIT FROM
THE PREVIOUS RUN...AND ABOUT A 16-MB SURFACE PRESSURE GRADIENT FROM
NE NEVADA TO SAN DIEGO. HENCE...LOOKS LIKE SOME DECENT NE WINDS
THROUGH/BELOW PASSES AND CANYONS...WITH POSSIBLE GUSTS OVER 55
MPH...MAINLY INLAND EMPIRE/SANTA ANA MTNS/SAN DIEGO COUNTY MTNS. THE
OFFSHORE FLOW SHOULD FINALLY BRING SOME WARMING W OF THE MTNS. THE
NEXT INSIDE-SLIDER TROUGH FOR TUESDAY LOOKS MUCH WEAKER AND FURTHER
NE THAN MODEL SOLUTIONS FROM YESTERDAY...INCLUDING IN MOST OF THE
ENSEMBLE RUNS. HENCE...GENERALLY FAIR WEATHER WITH SEASONAL TEMPS
THEN.
&&
.AVIATION...
211600Z...A WEAK COASTAL EDDY WILL CONTINUE SCT-BKN LOW CLOUDS ALONG
THE COAST AND IN THE INLAND VALLEYS THROUGH THIS MORNING...WITH BASES
BETWEEN 2500 AND 3500 FT MSL AND TOPS TO 5000 TO FT MSL. A WEAK
WEATHER DISTURBANCE MOVING OVER THE AREA THIS AFTERNOON WILL BRING
ISOLATED LIGHT SHOWERS OVER AND WEST OF THE MOUNTAINS...MOSTLY
CONFINED TO SAN DIEGO COUNTY. HOWEVER...HAVE OPTED TO KEEP KSAN TAF
FEW/SCT040 WITH CONFIDENCE TOO LOW TO INCLUDE ANY PRECIPITATION.
CLOUD COVER WILL BE DECREASING OVERNIGHT OVER ALL AREAS.
&&
.MARINE...
THE SMALL CRAFT ADVISORY FOR THE OUTER COASTAL WATERS HAS BEEN
ALLOWED TO EXPIRE. HOWEVER...COMBINED SEAS OF 7 TO 9 FEET ARE
EXPECTED THROUGH LATE THIS MORNING...AS WINDS CONTINUE TO DIMINISH.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
PUBLIC...MAXWELL
AVIATION/MARINE...JT
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1041 AM CST THU FEB 21 2013
.DISCUSSION...
ISSUED 1024 AM CST THU FEB 21 2013
WINTER WEATHER STORM SPINNING UP OVER MISSOURI AND ON TRACK FOR
ILX THIS AFTERNOON. SOME MINOR MIX OF PRECIPITATION ON THE LEADING
EDGE...BUT MAINLY SNOW EXPECTED WEST AND NORTHWEST OF THE I-55
CORRIDOR. FREEZING RAIN STILL ANTICIPATED ON THE BACK EDGE OF THE
SYSTEM...AND IN THE SOUTHEAST...PARTICULARLY ALONG AND SOUTH OF A
LINE ROUGHLY FROM PARIS TO TAYLORVILLE. GOING FORECAST IS ACTUALLY
ON TRACK...AND CONSIDERING THE WINTRY MIX AND CURRENT
VARIABLES...NO REASON TO ALTER THE FORECAST BEYOND WHAT IS
CURRENTLY IN THE GRIDS SIGNIFICANTLY. HAVE ALTERED HOURLY TEMPS
AND SKY COVER...BUT PRECIP TRENDS ON TRACK. MAJOR CONCERN FOR
AFFECTING THE SNOW TOTAL AMOUNTS ARE TWO FOLD...ONE...THE SYSTEM
WILL LIKELY BE QUICK IN PASSING AND TOTALS WILL HAVE TO
ACCUMULATE QUICKLY TO MAKE AN IMPACT BEFORE THE AREA IS OVERTAKEN
BY THE DRY SLOT. TWO...THOUGH THUNDER ACTIVITY IS EXPECTED TO
REDUCE AS THE SYSTEM PULLS THROUGH CENTRAL IL...SOME ISOLATED
THUNDER IS STILL QUITE POSSIBLE. AREAS AFFECTED BY A CONVECTIVELY
ENHANCED STORM HAVE THE POTENTIAL TO SEE LOCALIZED HIGHER TOTALS.
WINTER WEATHER ADVISORIES AND TIMING REMAIN UNCHANGED.
HJS
&&
.AVIATION...
ISSUED 532 AM CST THU FEB 21 2013
LARGE STRATOCUMULUS DECK AROUND 2000 FEET IS ADVECTING IN FROM THE
NORTHEAST...WITH AWIPS TIMING TOOLS INDICATING ARRIVAL FROM KBMI-
KCMI BY AROUND 13Z. RAP MODEL HUMIDITY PLOT AT 2500 FEET LINES UP
WELL...AND SUGGESTS IT SHOULD CONTINUE TOWARD KPIA AND KDEC TOWARD
16-17Z. WILL KEEP THESE MVFR CEILINGS OUT OF KSPI FOR NOW...BUT
CONDITIONS THERE WILL RAPIDLY DETERIORATE EARLY THIS AFTERNOON
WITH SNOW MOVING IN FROM THE SOUTHWEST TOWARD 21Z. THIS
PRECIPITATION WILL OVERSPREAD THE REMAINING TAF SITES BY ABOUT
23Z...WITH IFR OR LIFR CONDITIONS BECOMING WIDESPREAD. FORECAST
SOUNDINGS SHOWING SOME FREEZING RAIN POTENTIAL AT KSPI/KDEC EARLY
THIS EVENING AS WELL. HEAVIEST PRECIPITATION EXPECTED THROUGH
ABOUT 04-05Z...WITH A GRADUAL TREND TOWARD FREEZING DRIZZLE AT ALL
TAF SITES AFTER 06Z.
GEELHART
&&
.PREV DISCUSSION...
ISSUED 340 AM CST THU FEB 21 2013
WILL CONTINUE THE WINTER WEATHER ADVISORY ACROSS CENTRAL AND
SOUTHEAST IL BUT START IT AT NOON IN AREAS FROM SPRINGFIELD SW
AND START AT 3 PM REST OF CWA. WINTER WX ADVISORY GOES THROUGH 6
AM FRIDAY EXCEPT THROUGH NOON FRIDAY FROM LINCOLN NORTH. INCREASED
ICE ACCUMULATIONS OVER SE IL TO BETWEEN A TENTH AND A QUARTER INCH
AND ALSO ADDED ISOLATED THUNDERSTORMS TO SW AREAS LATE TODAY.
BRUNT OF SNOW STILL EXPECTED TO DEVELOP FROM SW TO NE DURING THE
AFTERNOON AND CONTINUE THIS EVENING BEFORE DIMINISHING OVERNIGHT.
SNOWFALL AMOUNTS TO RANGE FROM LESS THAN 1 INCH FROM I-70 SE TO
3-5 INCHES FROM I-55 NW WITH HIGHEST AMOUNTS NW OF THE IL RIVER.
BETWEEN 1 AND 3 INCHES OF SNOW OVER EAST CENTRAL IL WITH ICE
ACCUMULATIONS UP TO A TENTH INCH AS FAR NORTH AS I-72.
SHORT TERM...TODAY THROUGH SUNDAY
STRONG 541 DM 500 MB LOW NEAR THE SOUTHERN AZ/NM BORDER THAT
BROUGHT SNOW AS FAR SOUTH AS TUCSON IN SOUTHERN AZ THIS PAST NIGHT
HAS 996 MB LOW PRESSURE OVER NE NM. 1042 DM 500 MB ARCTIC HIGH
PRESSURE OVER NW ONTARIO AND RIDGING SOUTHWARD INTO IL AND TN VALLEY
BRINGING ANOTHER COLD NIGHT WITH TEMPS IN THE MID TO UPPER TEENS
CENTRAL IL AND LOWER 20S IN SE IL.
MODELS EJECT UPPER LEVEL LOW NE INTO THE CENTRAL PLAINS BY THIS
EVENING AND INTO WI FRI EVENING. STRONG SURFACE LOW IN NE NM TO
WEAKEN AS IT EJECTS NE INTO SE KS BY THIS EVENING AND INTO NW IL
BY MIDDAY FRI. MODELS HAVE TRENDED FURTHER SE WITH LOW PRESSURE
TRACK AND ALSO WITH COLDER AIR. MODELS IN GOOD AGREEMENT THAT MOST
OF CENTRAL/SE IL WILL STAY DRY THIS MORNING WITH SNOW SPREADING NE
ACROSS AREA DURING THE AFTERNOON THOUGH NOT TO AREAS NE OF I-74
UNTIL CLOSER TO 6 PM. SLEET MIXED IN WITH SNOW FROM I-72 SOUTH
WITH FREEZING RAIN POSSIBLE TOO IN SE IL ESPECIALLY LATER THIS
AFTERNOON. SPC HAS CHANCE OF THUNDERSTORMS FROM I-72 SOUTH THIS
AFTERNOON AND ADDED ISOLATED THUNDERSTORMS LATER THIS AFTERNOON TO
SW AREAS. THIS COULD ENHANCE SNOWFALL RATES OF 1-2 INCHES PER
HOURS IN A FEW CONVECTIVE BANDS THIS LATER THIS AFTERNOON AND
EARLY EVENING. USED A 10-12:1 SNOW RATIO FOR THIS EVENT PER BUFKIT.
MIXED PRECIPITATION TO GRADUALLY SPREAD NORTHWARD DURING TONIGHT
WITH AND DIMINISH TO FREEZING DRIZZLE DURING OVERNIGHT AS WE LOSE
MID LEVEL MOISTURE. AS STATED ABOVE...ICE ACCUMULATIONS UP TO A
TENTH INCH AS FAR NORTH AS I-72 WITH LESS THAN A TENTH INCH NORTH
OF I-72. BETWEEN A TENTH AND A QUARTER INCH OF ICE IN SOUTHEAST IL
FROM I-70 SOUTH WITH HIGHEST AMOUNTS FROM EFFINGHAM AND CLAY
COUNTY SW. SNOWFALL AMOUNTS LESS THAN 1 INCH FROM I-70 SE WHILE 3-5
INCHES FROM I-55 NW WITH HIGHEST AMOUNTS OF 4-6 INCHES NW BY KNOX...
FULTON AND SCHUYLER COUNTIES. SOME BLOWING SNOW POSSIBLE ESPECIALLY
NW AREAS WITH EAST WINDS INCREASING TO 15-20 MPH WITH GUSTS TO
AROUND 30 MPH THIS AFTERNOON AND EVENING.
LINGERING FREEZING DRIZZLE AND LIGHT SNOW FRIDAY NORTHERN AREAS
AND CONTINUE THE WINTER WX ADVISORY THROUGH NOON FRIDAY NORTH OF I-72.
SHOULD RISE ABOVE FREEZING FOR CENTRAL AND SE COUNTIES TO CHANGE
ANY LINGERING PRECIPITATION TO PATCHY DRIZZLE. WEAKENING UPPER
LEVEL LOW MOVES INTO MI SAT/SAT NIGHT WITH PRECIPITATION ENDING OVER
CENTRAL IL AND LOW CLOUDS DECREASING. TEMPS COOLING WITH HIGHS
AROUND 30F NORTH AND UPPER 30S IN SE IL SAT. DRY WEATHER CONTINUES
SUNDAY WITH TEMPS MODIFYING AS UPPER LEVEL RIDGE PUSHES EAST INTO
THE MS VALLEY AS WEAK SURFACE HIGH SETTLES OVER IL BY MIDDAY SUNDAY.
LONG TERM...SUNDAY NIGHT THROUGH WEDNESDAY
EXTENDED MODELS HAVE TRENDED A BIT COLDER WITH NEXT CUTOFF UPPER
LEVEL LOW EJECTING NE FROM THE SOUTHERN ROCKIES INTO IL BY TUE
MORNING. GFS APPEARS TOO FAST WITH THIS CUTOFF UPPER LEVEL LOW AND
TRENDED FORECASTER TOWARD SLOWER ECMWF. BEST CHANCES OF
PRECIPITATION LATER MONDAY INTO TUESDAY. MAINLY RAIN OVER SE IL
WHILE MIX OF RAIN/SNOW OVER CENTRAL IL. UPPER LEVEL LOW TO LINGER
OVER THE GREAT LAKES REGION MIDDLE OF NEXT WEEK AND COULD KEEP
CLOUDS AROUND LONGER ALONG WITH LOW CHANCES OF LIGHT PRECIPITATION
ESPECIALLY NE AREAS. STUCK CLOSE TO ALLBLEND TEMPS DURING THIS
TIME WHICH IS CLOSE TO NORMAL FOR LATE FEBRUARY.
07
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 6 AM CST
FRIDAY FOR ILZ043>046-053>057-061>063-066>068-071>073.
WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO NOON CST
FRIDAY FOR ILZ027>031-036>038-041-042.
WINTER WEATHER ADVISORY UNTIL 6 AM CST FRIDAY FOR ILZ040-047>052.
&&
$$
AREA FORECAST DISCUSSION
NWS DES MOINES IA
358 PM CST THU FEB 21 2013
.SHORT TERM /TONIGHT/...
SNOW BAND ADVECTING NORTHWARD ACROSS MUCH OF THE FORECAST AREA THIS
AFTERNOON INTO THE EVENING CAUSING RAPIDLY DETERIORATING CONDITIONS.
MODELS REMAIN IN GREAT AGREEMENT WITH TIMING AND PLACEMENT OF
HEAVIEST BAND TONIGHT AND WITH THE UPPER LOW TRACK DURING THE
OVERNIGHT HOURS. LEANED TOWARD THE TIMING OF NAM12/HRRR/HIRES
ARW-WRF FOR BAND DURING THE EVENING HOURS AND SREF/NAM OVERNIGHT.
IMPRESSIVE ISENTROPIC LIFT AHEAD OF THE UPPER LOW...GENERALLY ALONG
THE 285K TO 305K ISENTROPIC SURFACES...COMBINED WITH GOOD MOISTURE
TRANSPORT WILL CONTINUE TO PUSH THE CURRENT SNOW BAND FURTHER NORTH
LATE THIS AFTERNOON AND EVENING. THE ISENTROPIC LIFT DIMINISHES IN
STRENGTH AS THE UPPER LOW APPROACHES FROM KANSAS LATER TONIGHT INTO
THE OVERNIGHT HOURS BUT ENOUGH DEEP FORCING ASSOCIATED WITH IT AS IT
PASSES THROUGH THE STATE TO KEEP HIGH POPS GOING OVERNIGHT.
ALSO...EXPECTING THE SNOW TO CONTINUE TO FILL IN ACROSS SOUTHWEST
IOWA AND REMAIN FAIRLY PERSISTENT ACROSS THE FORECAST AREA FOR
SEVERAL HOURS TONIGHT. RAP CONFIRMS THIS AS IT HAS MAX OMEGA WITHIN
THE DENDRITIC LAYER PERSISTING THROUGH 02Z AT DSM...AND THROUGH 06Z
ACROSS NORTH CENTRAL IOWA. EVEN WITH SNOW INTENSITIES
DIMINISHING...STILL EXPECTING LIGHTER SNOWFALL ACCUMULATIONS B/T 06Z
AND 12Z FRIDAY WITH PASSAGE OF THE UPPER LOW. LEANED TOWARD A BLEND
OF THE GFS/NAM FOR QPF AMOUNTS AND STILL ON TRACK FOR GOOD SWATH OF
6 TO 9 INCHES GENERALLY SOUTH OF HIGHWAY 20. SLIGHTLY LESS FURTHER
NORTH AS THE BEST FORCING SKIRTS TO ITS SOUTHEAST.
SHARP PRESSURE GRADIENT ACROSS THE STATE KEEPS EAST TO NORTHEAST
WINDS GUSTS THROUGH 03-06Z TONIGHT BEFORE DIMINISHING. 925MB WINDS
AT 03Z STILL GUSTING AT 30KTS OVER CENTRAL PORTION OF THE FORECAST
AREA. VISIBILITY RAPIDLY DIMINISHING WITH THE ONSET OF THE SNOW AND
WILL PERSIST BEFORE THE WINDS WEAKEN LATER THIS EVENING.
.LONG TERM /FRIDAY THROUGH THURSDAY/...
UPPER LOW WILL BE DEPARTING TO THE NORTHEAST ON FRIDAY WITH FORCING
SUBSIDING THROUGH THE DAY. HAVE CONTINUED CATEGORICAL WORDING IN
THE FAR NORTHEAST DURING THE MORNING WITH A DECENT GRADIENT TO
ESSENTIALLY NO PCPN IN FAR SOUTHWEST. SUBSIDENCE WILL CONTINUE TO
OVERSPREAD THE AREA DURING THE DAY AND HAVE CUT THE POPS OFF ACROSS
THE SOUTH BY AFTERNOON AND LEFT SCATTERED SNOW SHOWERS AND FLURRIES
IN THE NORTH UNDER THE UPPER LOW WHERE SOME WEAK LIFT WILL CONTINUE
TO RESIDE. THE THREAT OF ANY PCPN WILL END BY SATURDAY NIGHT IN THE
NORTH AS THE SYSTEM PULLS AWAY. THE 850MB THERMAL TROF IS NEARLY
ASSOCIATED WITH THE UPPER LOW SO WARM ADVECTION WILL COMMENCE
IMMEDIATELY ON FRIDAY NIGHT INTO SATURDAY ON BACKSIDE OF THE SYSTEM.
THIS WILL KEEP TEMPERATURES FROM DROPPING AS MUCH AS WOULD BE
EXPECTED WITH FRESH SNOW COVER WITH HIGHS ON SUNDAY APPROACHING OR
SLIGHTLY ABOVE FREEZING.
FOCUS WILL THEN SHIFT ON SHORTWAVE DROPPING INTO THE ROCKIES DURING
THE WEEKEND. GFS IS FARTHER NORTH AND FASTER WITH THE EVOLUTION OF
THIS SYSTEM AND APPEARS TO BE THE ODD MODEL OUT. THE EURO AND GEM
HAVE BEEN MORE CONSISTENT DIGGING THE SYSTEM THROUGH THE
INTERMOUNTAIN WEST THEN MOVING THE STORM EASTWARD THROUGH THE MID
MISSISSIPPI RIVER VALLEY. THE IMPLICATIONS OF THIS WOULD BE TO KEEP
THE BULK OF FORCING AND MOISTURE TO OUR SOUTH WITH MISSOURI SEEING
THE WORST CONDITIONS. HOWEVER...SOME WEAKER FORCING WILL BLEED INTO
THE STATE AS THE UPPER TROF IS ELONGATED FROM THE CENTRAL INTO THE
NORTHERN PLAINS. THEREFORE...SOME SNOWFALL IS STILL EXPECTED ACROSS
THE STATE FROM LATE SUNDAY NIGHT INTO TUESDAY MORNING...PRIMARILY
IMPACTING THE SOUTHERN HALF OF IOWA. SOME LIGHT TO MODERATE
ACCUMULATIONS ARE EXPECTED WITH THIS STORM AND WILL CONTINUE TO
MONITOR THE TRACK SINCE ANY NORTHWARD SHIFT WOULD BEGIN TO BRING
SIGNIFICANTLY HIGHER AMOUNTS INTO THE STATE. AFTER THIS SYSTEM
PULLS AWAY...DRIER CONDITIONS ARE EXPECTED WITH TEMPERATURES BELOW
NORMAL WITH COOL NORTHERLY FLOW BEHIND THE SYSTEM.
&&
.AVIATION...21/18Z
SNOW DEVELOPING OVER SOUTHERN IOWA WILL CONTINUE TO PUSH NORTH AND
AFFECT DSM/OTM OVER THE NEXT 2-3 HOURS. HAVE MVFR CONDITIONS QUICKLY
DIMINISHING TO LIFR CONDITIONS AT DSM/OTM AFTER 21Z AND WILL PERSIST
THROUGH THE EARLY EVENING HOURS. TIMING FOR ALO/MCW/FOD IS LATER
THIS AFTERNOON/EARLY EVENING. CONFIDENCE IS HIGH WITH RAPIDLY
DETERIORATING CONDITIONS. EXPECTING A GOOD 4-6 HOUR PERIOD OF BLSN
AND LIFR VIS BEFORE SNOW BECOMES LIGHTER LATER THIS EVENING. HAVE
IFR/MVFR VIS/CIGS THROUGH FRIDAY MORNING.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL NOON CST FRIDAY FOR
ADAIR-ADAMS-APPANOOSE-AUDUBON-BOONE-CALHOUN-CARROLL-CASS-CLARKE-
CRAWFORD-DALLAS-DAVIS-DECATUR-GREENE-GUTHRIE-JASPER-LUCAS-MADISON-
MAHASKA-MARION-MONROE-POLK-POWESHIEK-RINGGOLD-SAC-STORY-TAYLOR-UNION-
WAPELLO-WARREN-WAYNE-BLACK HAWK-BREMER-BUTLER-CERRO GORDO-EMMET-
FRANKLIN-GRUNDY-HAMILTON-HANCOCK-HARDIN-HUMBOLDT-KOSSUTH-MARSHALL-
PALO ALTO-POCAHONTAS-TAMA-WEBSTER-WINNEBAGO-WORTH-WRIGHT.
&&
$$
AVIATION/SHORT TERM...KLP
LONG TERM...COGIL
AREA FORECAST DISCUSSION
NWS TOPEKA KS
342 PM CST THU FEB 21 2013
.DISCUSSION...
TONIGHT THROUGH FRIDAY...
THE UPPER LEVEL LOW WAS LOCATED ACROSS THE NORTHEAST TEXAS PANHANDLE
THIS AFTERNOON. ONE 1.5PV ANOMALY WAS LIFTING NORTHWARD ACROSS WEST
CENTRAL KS...WITH A SECOND 1.5PV ANOMALY OVER WESTERN OK. THE
SHORT-TERM MODELS...HRRR AND RAP SHOW THE 1.5PV ANOMALY
LIFTING NORTHEAST ACROSS EASTERN KS. AHEAD OF THE 1.5PV ANOMALY THE
FRONTOGENETICAL FORCING SHOULD INCREASE TO PROVIDE A PERIOD OF LIGHT
SNOW. THE MODELS SHOW AN INCREASE IN THE NEGATIVE SATURATED
EPV...CSI...WHICH COULD CAUSE SOME SLIGHTLY HEAVIER SNOW
BANDS...THUS THE WESTERN AND CENTRAL COUNTIES OF THE CWA COULD SEE
SOME LOCALLY HIGHER SNOW AMOUNTS.
UNTIL THE DENDRITIC GROWTH ZONE SATURATES LATER THIS AFTERNOON
THERE MAY BE PERIODS OF FREEZING DRIZZLE ACROSS THE EASTERN HALF OF
THE CWA. THE PATCHY FREEZING DRIZZLE MAY REFORM LATER THIS EVENING
ONCE THE STRONGER ASCENT SHIFTS NORTHEAST OF THE CWA. ISENTROPIC
DOWNGLIDE SHOULD BRING AN END THE THE FREEZING DRIZZLE CHANCE AFTER
MIDNIGHT.
THE STORM TOTAL SNOWFALL WILL RANGE FROM 6 TO 15 INCHES WITH SOME
LOCALLY HIGHER AMOUNTS.
I WILL KEEP THE WINTER STORM WARNING IN EFFECT UNTIL 00Z FOR THE
WESTERN HALF OF THE CWA AND UNTIL MIDNIGHT FOR THE EASTERN HALF OF
THE CWA.
FRIDAY...THE SKIES SHOULD BEGIN TO CLEAR FROM WEST TO EAST ACROSS
THE CWA THROUGH THE MID AND LATE MORNING HOURS. HIGHS WILL CONTINUE
TO BE COLD WITH MID 20S...GIVEN SEVERAL INCHES OF SNOW COVER.
GARGAN
FRIDAY NIGHT THROUGH THURSDAY...
DRY CONDITIONS ARE EXPECTED FOR THE START OF THE WEEKEND AS THE
UPPER LEVEL TROUGH THAT IMPACTED THE REGION WITH WINTER WEATHER
TODAY SLIDES NORTH TOWARD THE GREAT LAKES REGION. SURFACE HIGH
PRESSURE BRIEFLY WILL SETTLE INTO THE REGION BEHIND THE EXITING
STORM SYSTEM BEFORE THE NEXT UPPER LEVEL TROUGH BEGINS TO DIG
SOUTHWARD ACROSS THE NORTHERN AND CENTRAL PLAINS DURING THE LATTER
PART OF THE WEEKEND. THERE IS STILL UNCERTAINTY AMONGST THE MODELS
REGARDING JUST HOW FAR SOUTH THIS TROUGH WILL DIG ALONG AND EAST OF
THE ROCKY MOUNTAINS AND HOW QUICKLY THE UPPER LOW EJECTS
NORTHEASTWARD ACROSS THE FORECAST AREA AND FURTHER EAST OF THE AREA.
THESE MODEL DISCREPANCIES LEAD TO DIFFICULTIES IN PINNING DOWN THE
TIMING OF ANY PRECIPITATION FROM THIS SYSTEM. MODELS SEEM TO BE A
BIT SLOWER IN BRINGING THE SYSTEM INTO THE AREA...SO HAVE DECREASED
POPS FOR SUNDAY WITH CHANCE POPS FOR THE SUNDAY NIGHT THROUGH MONDAY
NIGHT TIMEFRAME. THESE POPS BEST REFLECT A BLEND OF THE ECMWF/GEM.
THE GFS CURRENTLY IS AN OUTLIER IN KEEPING THE UPPER TROUGH FURTHER
NORTH AND ONLY HAVING PRECIPITATION SKIMMING ACROSS THE NORTHERN
PORTION OF THE FORECAST AREA. DEPENDING UPON THE TIMING OF
PRECIPITATION...THE REGION COULD SEE A COMBINATION OF RAIN AND SNOW
SHOWERS WITH THIS SYSTEM. AT THIS TIME...THE SYSTEM LOOKS TO EXIT
EAST OF THE AREA BY TUESDAY. A WEAK RIDGE WILL MOVE INTO THE REGION
BEHIND THIS TROUGH WITH DRY CONDITIONS EXPECTED FOR MID-WEEK. BY THE
END OF THE PERIOD MODEL DISCREPANCIES EXIST WITH REGARDS TO THE NEXT
SHORTWAVE THAT EJECTS INTO THE CENTRAL PLAINS. KEPT ANY MENTION OF
PRECIPITATION OUT OF THE FORECAST AT THIS TIME.
TEMPERATURE FORECASTS FOR THE PERIOD HAVE BEEN COMPLICATED BY THE
SEVERAL INCHES OF SNOW RECEIVED ACROSS THE FORECAST AREA FROM
TODAY`S STORM. WITH THIS IN MIND...HAVE TRENDED WITH TEMPERATURES
STAYING BELOW THE SEASONAL NORMALS THROUGH THE EXTENDED FORECAST
PERIOD...WITH HIGHS GENERALLY IN THE 30S. THE COLDEST NIGHT LOOKS TO
BE FRIDAY NIGHT/EARLY SATURDAY MORNING AS LOW TEMPERATURES PLUMMET
INTO THE SINGLE DIGITS...WITH WIND CHILL VALUES ANYWHERE FROM ZERO
TO 8 BELOW ZERO. OTHERWISE...LOWS GENERALLY LOOK TO BE IN THE TEENS
AND 20S. TEMPERATURE FORECASTS WILL NEED TO BE ADJUSTED DEPENDING
UPON ANY MELTING OF SNOW THAT OCCURS IN THE UPCOMING DAYS.
ACH
&&
.AVIATION...
THE HEAVIER SNOW HAS MOVED NORTH OF THE KTOP AND KFOE TAF SITES.
LIGHT TO AT TIMES MODERATE SNOW WILL REDEVELOP LATER THIS
AFTERNOON INTO THE EVENING HOURS...WHICH WILL MAY REDUCE
VISIBILITIES BELOW 1SM. KMHK MAY KEEP LIGHT SNOW WITH POTENTIALLY
SOME HEAVIER SNOW DROPPING VISIBILITIES TO 1/4 MILES AT TIMES. THE
SNOW SHOULD END AT ALL TAF SITES AFTER 4Z. CEILINGS WILL VARY FROM
IFR TO MVFR DEPENDING ON SNOWFALL RATES. IFR CEILINGS WILL MOVE IN
THIS EVENING ON THE NORTHWEST SIDE OF THE SURFACE LOW. THE IFR
CEILINGS MAY GRADUALLY RISE TO MVFR CEILINGS LATE TONIGHT.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL MIDNIGHT CST TONIGHT FOR KSZ010>012-
022>024-026-036>040-054>056-058-059.
WINTER STORM WARNING UNTIL 6 PM CST THIS EVENING FOR KSZ008-009-
020-021-034-035.
&&
$$
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
359 PM EST THU FEB 21 2013
.SYNOPSIS...
ISSUED AT 330 PM EST THU FEB 21 2013
SNOW WILL SPREAD NORTHEAST ACROSS THE AREA OVERNIGHT INTO FRIDAY
MORNING. A QUICK 1 TO 2 INCHES OF SNOW MAY AFFECT THE FRIDAY MORNING
COMMUTE. THIS WILL BE FOLLOWED BY A TRANSITION TO FREEZING DRIZZLE
LATER IN THE DAY. A CHANCE OF WINTRY PRECIPITATION WILL PERSIST
THROUGH SATURDAY NIGHT. THE NEXT CHANCES FOR PRECIPITATION WILL BE
MONDAY NIGHT AND TUESDAY...WHEN A MIX OF RAIN AND SNOW IS EXPECTED.
TEMPERATURES WILL MODERATE NEXT WEEK WITH HIGHS REACHING THE UPPER
30S.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 330 PM EST THU FEB 21 2013
WILL BE ISSUING A WINTER WEATHER ADVISORY FOR OUR SOUTHERN CWFA TO
ACCOUNT FOR POSSIBLE BRIEF INTENSE SNOWFALL DURING THE FRIDAY
MORNING COMMUTE. CALIBRATED SREF GUIDANCE SHOWS GREATER THAN 1 INCH
PER HOUR SNOWFALL PROBABILITIES ACROSS OUR SOUTHERN COUNTY WARNING
AREA IN THE 12-15Z TIMEFRAME FRIDAY. ALSO LATEST GRR SNOWTOOL
GUIDANCE FROM THE RAP SUGGESTS THAT 1"/HR RATES WILL BE POSSIBLE
AFTER 10Z. ADVISORY WILL BE COMING OUT SHORTLY.
AFTER THIS INITIAL BURST OF SNOWFALL...AGREE WITH THE PREVIOUS
DISCUSSION THAT IMPACTS SHOULD BE MINOR. THE RESPONSIBLE SYSTEM
CURRENTLY IN THE PLAINS WILL FILL AS IT SHEARS NORTHEAST. BEHIND THE
NARROW BUT POTENTIALLY INTENSE BAND OF WARM ADVECTION SNOW...ALL BUT
THE EXTREME NORTHERN PART OF THE FORECAST AREA DESATURATES IN THE
DGZ DURING THE LATE MORNING...MEANING A TRANSITION TO FREEZING
DRIZZLE AND THEN POSSIBLY DRIZZLE AS SURFACE TEMPERATURES WARM. ICE
ACCUMULATION IS EXPECTED TO BE MINIMAL... ESPECIALLY WITH THE
MITIGATING EFFECTS OF SNOW COVER...RESIDUAL SALT...AND DAYTIME
INSOLATION ALL DISCUSSED IN THE PREVIOUS AFD.
.LONG TERM...(SUNDAY THROUGH THURSDAY)
ISSUED AT 330 PM EST THU FEB 21 2013
A HIGH PRESSURE RIDGE WILL PRODUCE DRY WX WITH SEASONABLY COOL
TEMPERATURES SUNDAY THROUGH SUNDAY NIGHT. LOW PRESSURE TRACKING NE
INTO OUR REGION WILL BRING A SLIGHT CHANCE FOR A MIX OF LIGHT RAIN
AND LIGHT SNOW AS EARLY AS MONDAY BASED ON 12Z GFS GUIDANCE.
HOWEVER THE MUCH BETTER CHANCE FOR MIXED PCPN SHOULD HOLD OFF UNTIL
LATE MONDAY NIGHT AND TUESDAY AS SUGGESTED BY THE SLOWER AND
PREFERRED ECMWF 12Z GUIDANCE SOLUTION (WHICH IS CONSISTENT WITH PCPN
TIMING FROM THE 00Z RUN).
TEMPS WILL UNDERGO A GRADUAL MODERATING TREND DURING THE EARLY TO
MIDDLE PORTION OF NEXT WEEK WITH MAX TEMPS EXPECTED TO REACH THE
UPPER 30S TO LOWER 40S BY TUESDAY AND WEDNESDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY)
ISSUED AT 1225 PM EST THU FEB 21 2013
MVFR CONDITIONS WILL CONTINUE AT ALL THE TERMINALS THIS AFTERNOON
AND EVENING DUE TO LOW CLOUDS WITH CLOUD BASES OF 1.5 TO 2 KFT AGL.
CONDITIONS WILL DETERIORATE FROM MVFR TO IFR DURING THE EARLY
MORNING HOURS FRIDAY AS A BAND OF SNOW MOVES IN FROM SW TO NE.
IFR/LIFR CONDITIONS WILL CONTINUE FRIDAY MORNING THROUGH EARLY
FRIDAY AFTERNOON AS CIGS LOWER AND SNOW CONTINUES.
THERE IS ALSO SOME POTENTIAL FOR FREEZING DRIZZLE FROM MID MORNING
FRIDAY THROUGH 18Z FRIDAY MAINLY FOR THE TERMINALS ALONG THE I-94
CORRIROR. NOT ENOUGH POTENTIAL IN THIS TO WARRANT INCLUSION IN THE
TERMINAL FCSTS JUST YET... BUT WE WILL CONTINUE TO MONITOR FOR
THIS POTENTIAL.
&&
.MARINE...
ISSUED AT 359 PM EST THU FEB 21 2013
AFTER FURTHER CONSIDERATION...ISSUED A NEW SMALL CRAFT ADVISORY BEGINNING
TONIGHT TO ACCOUNT FOR STRENGTHENING EAST WINDS TOWARDS MORNING. ALTHOUGH
WAVE GROWTH WILL BE LIMITED SOMEWHAT BY POOR FETCH...SUSTAINED WINDS
WELL IN EXCESS OF 20 KTS TOWARDS SUNRISE WILL GREATLY INCREASE THE
HAZARD.
&&
.HYDROLOGY...
ISSUED AT 330 PM EST THU FEB 21 2013
WITH ADDITIONAL QPF EXPECTED TO STAY WELL UNDER HALF AN INCH...THERE
ARE NO CONCERNS AT THIS TIME.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...WINTER WEATHER ADVISORY FROM 4 AM TO 1 PM EST FRIDAY FOR MIZ050-
056>059-064>067-071>074.
LM...SMALL CRAFT ADVISORY FROM 1 AM FRIDAY TO 5 PM EST SATURDAY FOR
LMZ844>849.
&&
$$
SYNOPSIS...TJT
SHORT TERM...TJT
LONG TERM...LAURENS
AVIATION...LAURENS
HYDROLOGY...TJT
MARINE...TJT
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
330 PM EST THU FEB 21 2013
.SYNOPSIS...
ISSUED AT 330 PM EST THU FEB 21 2013
SNOW WILL SPREAD NORTHEAST ACROSS THE AREA OVERNIGHT INTO FRIDAY
MORNING. A QUICK 1 TO 2 INCHES OF SNOW MAY AFFECT THE FRIDAY MORNING
COMMUTE. THIS WILL BE FOLLOWED BY A TRANSITION TO FREEZING DRIZZLE
LATER IN THE DAY. A CHANCE OF WINTRY PRECIPITATION WILL PERSIST
THROUGH SATURDAY NIGHT. THE NEXT CHANCES FOR PRECIPITATION WILL BE
MONDAY NIGHT AND TUESDAY...WHEN A MIX OF RAIN AND SNOW IS EXPECTED.
TEMPERATURES WILL MODERATE NEXT WEEK WITH HIGHS REACHING THE UPPER
30S.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 330 PM EST THU FEB 21 2013
WILL BE ISSUING A WINTER WEATHER ADVISORY FOR OUR SOUTHERN CWFA TO
ACCOUNT FOR POSSIBLE BRIEF INTENSE SNOWFALL DURING THE FRIDAY
MORNING COMMUTE. CALIBRATED SREF GUIDANCE SHOWS GREATER THAN 1 INCH
PER HOUR SNOWFALL PROBABILITIES ACROSS OUR SOUTHERN COUNTY WARNING
AREA IN THE 12-15Z TIMEFRAME FRIDAY. ALSO LATEST GRR SNOWTOOL
GUIDANCE FROM THE RAP SUGGESTS THAT 1"/HR RATES WILL BE POSSIBLE
AFTER 10Z. ADVISORY WILL BE COMING OUT SHORTLY.
AFTER THIS INITIAL BURST OF SNOWFALL...AGREE WITH THE PREVIOUS
DISCUSSION THAT IMPACTS SHOULD BE MINOR. THE RESPONSIBLE SYSTEM
CURRENTLY IN THE PLAINS WILL FILL AS IT SHEARS NORTHEAST. BEHIND THE
NARROW BUT POTENTIALLY INTENSE BAND OF WARM ADVECTION SNOW...ALL BUT
THE EXTREME NORTHERN PART OF THE FORECAST AREA DESATURATES IN THE
DGZ DURING THE LATE MORNING...MEANING A TRANSITION TO FREEZING
DRIZZLE AND THEN POSSIBLY DRIZZLE AS SURFACE TEMPERATURES WARM. ICE
ACCUMULATION IS EXPECTED TO BE MINIMAL... ESPECIALLY WITH THE
MITIGATING EFFECTS OF SNOW COVER...RESIDUAL SALT...AND DAYTIME
INSOLATION ALL DISCUSSED IN THE PREVIOUS AFD.
.LONG TERM...(SUNDAY THROUGH THURSDAY)
ISSUED AT 330 PM EST THU FEB 21 2013
A HIGH PRESSURE RIDGE WILL PRODUCE DRY WX WITH SEASONABLY COOL
TEMPERATURES SUNDAY THROUGH SUNDAY NIGHT. LOW PRESSURE TRACKING NE
INTO OUR REGION WILL BRING A SLIGHT CHANCE FOR A MIX OF LIGHT RAIN
AND LIGHT SNOW AS EARLY AS MONDAY BASED ON 12Z GFS GUIDANCE.
HOWEVER THE MUCH BETTER CHANCE FOR MIXED PCPN SHOULD HOLD OFF UNTIL
LATE MONDAY NIGHT AND TUESDAY AS SUGGESTED BY THE SLOWER AND
PREFERRED ECMWF 12Z GUIDANCE SOLUTION (WHICH IS CONSISTENT WITH PCPN
TIMING FROM THE 00Z RUN).
TEMPS WILL UNDERGO A GRADUAL MODERATING TREND DURING THE EARLY TO
MIDDLE PORTION OF NEXT WEEK WITH MAX TEMPS EXPECTED TO REACH THE
UPPER 30S TO LOWER 40S BY TUESDAY AND WEDNESDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY)
ISSUED AT 1225 PM EST THU FEB 21 2013
MVFR CONDITIONS WILL CONTINUE AT ALL THE TERMINALS THIS AFTERNOON
AND EVENING DUE TO LOW CLOUDS WITH CLOUD BASES OF 1.5 TO 2 KFT AGL.
CONDITIONS WILL DETERIORATE FROM MVFR TO IFR DURING THE EARLY
MORNING HOURS FRIDAY AS A BAND OF SNOW MOVES IN FROM SW TO NE.
IFR/LIFR CONDITIONS WILL CONTINUE FRIDAY MORNING THROUGH EARLY
FRIDAY AFTERNOON AS CIGS LOWER AND SNOW CONTINUES.
THERE IS ALSO SOME POTENTIAL FOR FREEZING DRIZZLE FROM MID MORNING
FRIDAY THROUGH 18Z FRIDAY MAINLY FOR THE TERMINALS ALONG THE I-94
CORRIROR. NOT ENOUGH POTENTIAL IN THIS TO WARRANT INCLUSION IN THE
TERMINAL FCSTS JUST YET... BUT WE WILL CONTINUE TO MONITOR FOR
THIS POTENTIAL.
&&
.MARINE...
ISSUED AT 330 PM EST THU FEB 21 2013
BASED ON WEBCAMS AND LATEST LOCAL RUN OF THE GLERL...CANCELLED THE
SMALL CRAFT ADVISORY.
&&
.HYDROLOGY...
ISSUED AT 330 PM EST THU FEB 21 2013
WITH ADDITIONAL QPF EXPECTED TO STAY WELL UNDER HALF AN INCH...THERE
ARE NO CONCERNS AT THIS TIME.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&
$$
SYNOPSIS...TJT
SHORT TERM...TJT
LONG TERM...LAURENS
AVIATION...LAURENS
HYDROLOGY...TJT
MARINE...TJT
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1131 AM CST Thu Feb 21 2013
...UPDATED AVIATION DISCUSSION...
.DISCUSSION...
Intense winter storm is taking direct aim on the forecast area this
morning. Overnight model runs...including the near-term RAP and
HRRR models...now indicate a broad swath of 1"+ liquid-equivalent
precipitation totals overspreading most of the forecast area with the
heaviest axis centered very close to Kansas City. How these precip
totals translate into snow and sleet amounts is still somewhat of a
question mark given the presence of warm air in the 800-700 hPa layer
and a shallow depth of the max dendritic growth region. Seems most
methods are giving snow to liquid ratios on the order of 8:1 to 10:1
near I-70...and around 10:1 to 12:1 north of Highway 36. Applying
these ratios to expected precip totals now results in a broad swath
of 8 to 12 inch snows forecast for most of the forecast
area...generally along and north of a Paola...Marshall...Moberly
line. These areas are unlikely to see much if any sleet
contamination and could see some totals approach or exceed February
records (see climate section below). Still expect sleet to fall across
areas south of this line, and there could be a good deal of it.
Exactly how much sleet falls across these areas will have huge
impacts on snow amounts, which could be as low as 3 or 4 inches if
sleet lasts several hours...to as much as 8 to 10 inches if sleet is
only brief. Freezing rain still appears a possibility for the
Clinton/Sedalia/Boonville areas but any icing should be limited to a
tenth of an inch or less.
Looking upstream, synoptic and mesoscale ascent has become quite
strong and is coupled throughout a large depth of the atmosphere.
Combine this with strong moisture advection from the south, the
result has been an expanding area of heavy precipitation over
northern OK and southern KS with several bands of convection feeding
into it. In fact, lightning profilers have lit up vividly down there,
even in the stratiform precipitation over KS, suggestive of quite a
bit of slantwise and even upright instability. This instability will
spread into ern KS/wrn MO through the morning and could easily
result in occasional thunder and snowfall rates of 2" to 3" per hour.
Heaviest precipitation band will spread into northern MO through the
afternoon and taper off across the KC area by 21Z or so. However,
broad synoptic scale and weak deformation forcing will continue well
into the evening and overnight as the upper low moves overhead. This
could result in an extra 2" to 5" of snow from late afternoon into
the early morning hours particularly north of the Missouri River.
Hawblitzel
Friday and Saturday...
As the system departs, a few lingering snow showers may be possible
across far northeast Missouri, but little to no additional snow
accumulation is expected. Temperatures will have difficulty rising
much on Friday with widespread snow cover and colder air advecting
into the region, so have kept high temperatures only a few degrees
warmer than Thursday night lows. Frigid temperatures are possible
Friday night as surface high pressure drifts over western Missouri,
combining the residual snow cover with light winds and clear skies.
Warmer air will begin to build into the region on Saturday as the
upper low departs, but reaching highs much above freezing will be
difficult, especially without strong return flow at low levels.
Sunday and Monday...
Another deep trough axis will swing through the four corners region
on Sunday, bringing a deepening surface low into the southern High
Plains by early Monday. This system is currently projected to lift
northeast into the region on Monday afternoon, taking a somewhat
similar track to the current system; however, there is still a good
deal of uncertainty in this forecast. Moisture may be a bit more
limited with a smaller window of time to draw from the Gulf, and
this more southern track is a very recent trend with the 00z models,
so for now have kept probabilities relatively low and maintained a
rain or snow precipitation type to cover several possible scenarios.
Tuesday through Thursday...
Quieter conditions should prevail for the remainder of next week as
a more persistent ridge builds over the west. A few snow showers may
be possible Tuesday night into early Wednesday as a weak clipper
dives in behind the departing upper low, but any snowfall that does
occur should be fairly light, and the probability of measurable snow
is low. Temperatures will remain below normal as a result of cold
air wrapping behind the upper low and additional cold air dropping
southeast with the clipper, but should eventually recover when the
ridge over the Rockies begins to shift east.
Laflin
&&
.CLIMATE...
The last time Kansas City officially measured 12" of snow was
January 18-19 in 1962 (14.0"). The most recent snowfall greater than
10" was February 24-25 in 1993 (11.1").
Top 10 snowfalls for Kansas City
1. 24.2"...Mar 22-24 1912
2. 15.8"...Feb 11-12 1894
3. 14.6"...Jan 20-21 1958
4. 14.0"...Jan 18-19 1962
5. 13.8"...Mar 14-15 1960
6. 13.7"...Jan 8-9 1930
7. 13.0"...Feb 27-28 1900
8. 12.3"...Mar 29-31 1926
9. 12.2"...Dec 23-24 1918
10. 11.9"...Mar 3-5 1915
Top 5 daily February snowfalls for Kansas City
1. 11.8"...27th 1900
2. 10.5"...4th 1915
3. 8.7"...23rd 1990
4. 8.6"...2nd 1960
5. 8.0"...15th 1960
&&
.AVIATION...
For the 18Z TAFs...Heavy snow will tapper off to light snow this
afternoon as dry air aloft works across the terminals from southwest
to northeast. This may result in a brief period of improved
conditions, going from LIFR to MVFR, but conditions will come back
down into the IFR quickly so have left this out of the TAF.
Otherwise, precipitation type might convert to, or mix with, freezing
drizzle. Light snow is expected to persist through the afternoon and
evening hours with additional accumulations.
Cutter
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER STORM WARNING until Midnight CST tonight FOR MOZ028>030-
037>040-043>046-053-054.
WINTER STORM WARNING until 6 AM CST Friday FOR MOZ001>008-
011>017-020>025-031>033.
KS...WINTER STORM WARNING until Midnight CST tonight FOR KSZ057-060-
103>105.
WINTER STORM WARNING until 6 AM CST Friday FOR KSZ025-102.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1037 AM CST Thu Feb 21 2013
.UPDATE...
/1036 AM CST Thu Feb 21 2013/
...Shifting heaviest snow band a bit farther south...
Morning upper air sounding from Springfield showed a unstable
sounding, and sure enough that instability worked north feeding
moisture across the southern reaches of the forecast area. This helped
fuel thunder-snow that has reached as far north as North Kansas City
this morning. Radar trends and satellite imagery are pointing at the
heaviest snow band setting up across the southern half of the
forecast area this morning, shifting to the northeast through the
afternoon hours. Deformation zone snow is developing from northwest
Missouri back into south central Kansas, and will likely be what
brings significant snow accumulations to far northwest Missouri --this
afternoon and this evening--. South of a St Joseph to Kirksville
line...snowfall totals have been bumped up with the heaviest snow
expected to persist through the early to mid afternoon hours. Totals
of greater than 12 inches will be possible as far south as Highway
50. Dry slot is just shy of nosing into the southwest corner of the
forecast area, with reports of precipitation type beginning to
transit from snow and sleet to freezing drizzle. The Threat of
freezing rain continue to look very minimal, but will persist across
areas from east central Kansas into central Missouri through the mid-
afternoon hours.
Cutter
&&
.DISCUSSION...
Intense winter storm is taking direct aim on the forecast area this
morning. Overnight model runs...including the near-term RAP and
HRRR models...now indicate a broad swath of 1"+ liquid-equivalent
precipitation totals overspreading most of the forecast area with the
heaviest axis centered very close to Kansas City. How these precip
totals translate into snow and sleet amounts is still somewhat of a
question mark given the presence of warm air in the 800-700 hPa layer
and a shallow depth of the max dendritic growth region. Seems most
methods are giving snow to liquid ratios on the order of 8:1 to 10:1
near I-70...and around 10:1 to 12:1 north of Highway 36. Applying
these ratios to expected precip totals now results in a broad swath
of 8 to 12 inch snows forecast for most of the forecast
area...generally along and north of a Paola...Marshall...Moberly
line. These areas are unlikely to see much if any sleet
contamination and could see some totals approach or exceed February
records (see climate section below). Still expect sleet to fall across
areas south of this line, and there could be a good deal of it.
Exactly how much sleet falls across these areas will have huge
impacts on snow amounts, which could be as low as 3 or 4 inches if
sleet lasts several hours...to as much as 8 to 10 inches if sleet is
only brief. Freezing rain still appears a possibility for the
Clinton/Sedalia/Boonville areas but any icing should be limited to a
tenth of an inch or less.
Looking upstream, synoptic and mesoscale ascent has become quite
strong and is coupled throughout a large depth of the atmosphere.
Combine this with strong moisture advection from the south, the
result has been an expanding area of heavy precipitation over
northern OK and southern KS with several bands of convection feeding
into it. In fact, lightning profilers have lit up vividly down there,
even in the stratiform precipitation over KS, suggestive of quite a
bit of slantwise and even upright instability. This instability will
spread into ern KS/wrn MO through the morning and could easily
result in occasional thunder and snowfall rates of 2" to 3" per hour.
Heaviest precipitation band will spread into northern MO through the
afternoon and taper off across the KC area by 21Z or so. However,
broad synoptic scale and weak deformation forcing will continue well
into the evening and overnight as the upper low moves overhead. This
could result in an extra 2" to 5" of snow from late afternoon into
the early morning hours particularly north of the Missouri River.
Hawblitzel
Friday and Saturday...
As the system departs, a few lingering snow showers may be possible
across far northeast Missouri, but little to no additional snow
accumulation is expected. Temperatures will have difficulty rising
much on Friday with widespread snow cover and colder air advecting
into the region, so have kept high temperatures only a few degrees
warmer than Thursday night lows. Frigid temperatures are possible
Friday night as surface high pressure drifts over western Missouri,
combining the residual snow cover with light winds and clear skies.
Warmer air will begin to build into the region on Saturday as the
upper low departs, but reaching highs much above freezing will be
difficult, especially without strong return flow at low levels.
Sunday and Monday...
Another deep trough axis will swing through the four corners region
on Sunday, bringing a deepening surface low into the southern High
Plains by early Monday. This system is currently projected to lift
northeast into the region on Monday afternoon, taking a somewhat
similar track to the current system; however, there is still a good
deal of uncertainty in this forecast. Moisture may be a bit more
limited with a smaller window of time to draw from the Gulf, and
this more southern track is a very recent trend with the 00z models,
so for now have kept probabilities relatively low and maintained a
rain or snow precipitation type to cover several possible scenarios.
Tuesday through Thursday...
Quieter conditions should prevail for the remainder of next week as
a more persistent ridge builds over the west. A few snow showers may
be possible Tuesday night into early Wednesday as a weak clipper
dives in behind the departing upper low, but any snowfall that does
occur should be fairly light, and the probability of measurable snow
is low. Temperatures will remain below normal as a result of cold
air wrapping behind the upper low and additional cold air dropping
southeast with the clipper, but should eventually recover when the
ridge over the Rockies begins to shift east.
Laflin
&&
.CLIMATE...
The last time Kansas City officially measured 12" of snow was
January 18-19 in 1962 (14.0"). The most recent snowfall greater than
10" was February 24-25 in 1993 (11.1").
Top 10 snowfalls for Kansas City
1. 24.2"...Mar 22-24 1912
2. 15.8"...Feb 11-12 1894
3. 14.6"...Jan 20-21 1958
4. 14.0"...Jan 18-19 1962
5. 13.8"...Mar 14-15 1960
6. 13.7"...Jan 8-9 1930
7. 13.0"...Feb 27-28 1900
8. 12.3"...Mar 29-31 1926
9. 12.2"...Dec 23-24 1918
10. 11.9"...Mar 3-5 1915
Top 5 daily February snowfalls for Kansas City
1. 11.8"...27th 1900
2. 10.5"...4th 1915
3. 8.7"...23rd 1990
4. 8.6"...2nd 1960
5. 8.0"...15th 1960
&&
.AVIATION...
For the 12Z TAFs...major winter storm will impact all terminals for
much of the day with very heavy snow rates of 1 to 2 inches per hour,
possibly more. Occasional lightning is also possible. This activity
is right on the doorstep, so will go ahead and introduce heavy snow
to the KC and STJ terminals right at the onset of the TAF period. The
heavy nature of the snow is likely to bring every airport below
operational minimums at times. Heaviest snow will gradually taper
off across KC/STJ by mid afternoon, and across central and northeast
MO late afternoon. However, additional light snow through the evening
could produce additional light accumulations and prolonged IFR
conditions through the night.
Hawblitzel
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER STORM WARNING until Midnight CST tonight FOR MOZ028>030-
037>040-043>046-053-054.
WINTER STORM WARNING until 6 AM CST Friday FOR MOZ001>008-
011>017-020>025-031>033.
KS...WINTER STORM WARNING until Midnight CST tonight FOR KSZ057-060-
103>105.
WINTER STORM WARNING until 6 AM CST Friday FOR KSZ025-102.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1144 AM CST THU FEB 21 2013
.SHORT TERM...TODAY
921 AM CST THU FEB 21 2013
QUICK UPDATE TO THE FORECAST TO ACCOUNT FOR STRATUS DECK THAT HAS
FORMED ACROSS CENTRAL AND EASTERN WISCONSIN THIS MORNING. THIS
HAS NOW PUSHED WEST INTO THE FORECAST AREA...AND 21.12Z NAM AND
21.13Z RAP CAPTURE THE LOW LEVEL SATURATION VERY WELL...BRINGING
IT AROUND THE MISSISSIPPI RIVER IN THE LATE MORNING...THEN ACROSS
MOST OF THE AREA BY EARLY AFTERNOON. THE SATURATION IS OCCURRING
IN THE DENDRITIC GROWTH ZONE GIVEN THE COLD TEMPERATURES THIS
MORNING SO LIGHT SNOW / FLURRIES ARE BEING REPORTED AS WELL. THIS
WILL PERSIST FOR MUCH OF THE LATE MORNING AND AFTERNOON HOURS.
VISIBILITY REDUCTIONS HAVE BEEN AS LOW AS 2 MILES...BUT MAINLY IN
THE 4 TO 6 MILE RANGE.
.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY
303 AM CST THU FEB 21 2013
21.00Z GFS/ECMWF SHOW A RIDGE OF HIGH PRESSURE DRIFTING ACROSS THE
REGION SATURDAY NIGHT THROUGH SUNDAY FOR A BRIEF DRY/QUIET PERIOD.
LOWS SATURDAY NIGHT ARE EXPECTED TO DROP INTO THE SINGLE
DIGITS/LOWER TEENS ABOVE ZERO WITH HIGHS ON SUNDAY RIGHT AROUND
NORMAL IN THE MIDDLE 20S TO LOWER 30S. ATTENTION THEN TURNS TO THE
NEXT STORM SYSTEM TO AFFECT THE AREA SUNDAY NIGHT THROUGH
WEDNESDAY. THIS SYSTEM LOOKS LIKE IT WILL GIVE THE AREA ANOTHER
SHOT OF LONG DURATION ACCUMULATING SNOW WITH PERHAPS A MIX OF
RAIN/SNOW IN THE SOUTH DURING THE DAY MON/TUE AS SURFACE
TEMPERATURES WARM A DEGREE OR TWO ABOVE THE FREEZING MARK. MODELS
PRETTY CLOSE...BUT STILL A BIT AT ODDS WITH THE EXACT TRACK OF THE
LOW. THIS WILL OF COURSE DETERMINE THE EXACT OUTCOME OF ACCUMULATING
SNOW AMOUNTS...DEFINITELY SOMETHING TO KEEP AN EYE ON.
&&
.AVIATION...THROUGH 18Z FRIDAY
1144 AM CST THU FEB 21 2013
CONDITIONS TO DETERIORATE AT KRST/KLSE TONIGHT AS A WINTER STORM
LIFTS TO THE REGION. THERE WILL BE SOME INITIAL DRY AIR AND
SATURATION ISSUES TO OVERCOME...BUT BY 04Z A BAND OF MODERATE
SNOW WILL IMPACT THE TAF SITES. SNOW RATES WITH THIS BAND LOOK TO
BE BETWEEN 1/2 AND 1 INCH PER HOUR. VISIBILITY AND CEILINGS WILL
RAPIDLY DROP TO LIFR...WITH THE WORST CONDITIONS EXPECTED BETWEEN
06Z AND 13Z FRIDAY. BY FRIDAY MORNING...3 TO 5 INCHES WILL HAVE
ACCUMULATED...HOWEVER SNOW WILL LINGER FOR MUCH OF THE DAY.
ADDITIONAL DAYTIME ACCUMULATIONS OF 2 TO 3 INCHES ARE EXPECTED AND
FLIGHT CONDITIONS WILL REMAIN IN LIFR THROUGH AT LEAST 18Z.
EASTERLY WINDS AROUND 10 KTS WILL PERSIST FOR THE ENTIRE PERIOD.
THE SNOW WILL DIMINISH LATE FRIDAY AFTERNOON LEADING TO SLOWLY
IMPROVING CONDITIONS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
303 AM CST THU FEB 21 2013
WI...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST
FRIDAY FOR WIZ041-053>055-061.
WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM CST
FRIDAY FOR WIZ017-029-032>034-042>044.
MN...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST
FRIDAY FOR MNZ079-086>088-094>096.
IA...WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 PM CST FRIDAY
FOR IAZ008>010-018-019-029-030.
WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST FRIDAY
FOR IAZ011.
&&
$$
SHORT TERM...ZT
LONG TERM...DAS
AVIATION...ZT