Forecast Discussions mentioning any of
"HRRR" "RR" "RUC13" "RUC" received at GSD on 12/03/11
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
331 PM MST THU DEC 1 2011
.SHORT TERM /TONIGHT THROUGH SATURDAY/...
LATE THIS AFTERNOON/EVENING...SNOW AND WIND WINDING DOWN ACROSS THE
NORTH AS FOCUS FOR WEATHER SHIFTS TO THE SOUTH.
THE CLOSED LOW WAS STILL NEAR THE CA/AZ BORDER PER WATER VAPOR
SATELLITE IMAGE. CLOUD TOPS COOLING OVER SW CO/SE UT THIS AFTERNOON
AHEAD OF A VORTICITY MAX SHOWN IN THE RUC MODEL TO BE OVER NORTHEAST
NM. THIS HAS PRODUCED A COUPLE INCHES OF NEW SNOW SOUTH OF SILVERTON
PER A REPORT FROM THE COLORADO AVALANCHE CENTER. CALL TO A SPOTTER IN
PARADOX...WHERE RADAR ECHOES HAVE BEEN STRONGEST...REVEALED JUST
CLOUDY SKIES TO LIKELY AT LEAST SOME LIGHT SNOW OVER THE HIGHER
PEAKS OF THE LA SALS AND UNCOMPAHGRE PLATEAU. THIS DISTURBANCE
EXPECTED TO MOVE INTO SW CO LATE TODAY BEFORE PEELING OFF TO THE
NORTHEAST. WILL KEEP SCATTERED SHOW SHOWERS OVER THE SAN JUANS MTNS.
MORE NUMEROUS SHOWERS IN SE UT CLOSER TO A SECOND AND STRONGER
DISTURBANCE ROTATING AROUND THE CLOSED LOW. CLEARING SKIES ACROSS THE
NORTH TONIGHT.
THE SOUTHWEST CLOSED LOW IS EXPECTED TO REMAIN OVER SWRN AZ TONIGHT
BEFORE OPENING UP AND SLOWLY MOVING EAST FRI-FRI NIGHT AS ANOTHER
SPLITTING TROUGH DROPS SOUTH INTO THE GREAT BASIN. THIS EVENTUALLY
EXPECTED TO BRING ANOTHER COLD FRONT DOWN INTO THE FORECAST AREA FRI
NIGHT...AS ANOTHER CLOSED UPPER LOW DEVELOPS OVER AZ BY SAT. SIMILAR
SCENARIO TO THE CURRENT ONE EXCEPT ABSENT THE EXTREME NE WINDS THAT
WERE OBSERVED EARLY THIS MORNING.
SE TO S WINDS 20-30 KTS AT 700 MB WILL BE BRING SEVERAL INCHES OF
SNOW O THE SOUTHERN MTNS FRIDAY BEFORE RELAXING FRI NIGHT AS THE
SOUTHERLY OROGRAPHIC WINDS SUBSIDE. SNOW CHANCES INCREASE ACROSS THE
N FRI NIGHT AS THE SFC FRONT AND DEFORMATION ZONE ALOFT DROP IN FROM
THE NORTH...WITH SNOW FOCUS SHIFTING TO THE SOUTH SAT AFTERNOON AS
THE CLOSED LOW FULLY DEVELOPS OVER AZ. BUT...CONFIDENCE NOT THE
GREATEST GIVEN THE RATHER COMPLEX INTERACTION BETWEEN THE EXITING
FIRST CLOSED LOW AND THE SECOND TROUGH/LOW DROPPING SOUTH. ONE AREA
TO KEEP AN EYE ON IS THE SOUTHERN FOOTHILLS OF THE SAN JUAN MTNS IN
THE SOUTHERLY UPSLOPE FLOW.
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
INITIALLY THE MED RANGE MDLS START OUT IN GOOD AGREEMENT WITH UPPER
LOW OVER AZ MOVING EASTWARD TOWARD NM SATURDAY NIGHT. EC A BIT SLOWER
WITH THIS EASTWARD MOVEMENT BUT EITHER WAY ANY PCPN APPEARS TO BE
FOCUSED OVER THE SAN JUANS WHERE MOISTURE AND FORCING APPEAR BEST.
WILL RAISE POPS TO THE LIKELY CATEGORY THERE BUT LIMIT SNOWFALL TO
AROUND AN INCH OR LESS. OROGRAPHIC COMPONENT GENERALLY LACKING WITH
H7 WINDS GENERALLY 10KTS OR LESS. THE NEXT SIGNIFICANT SHRT WV IN
A HIGH AMPLITUDE NORTHERLY FLOW WILL DROP OUT OF CANADA SUNDAY AND
APPROACH OUR CWA FROM THE NORTHEAST. AT THE SAME TIME SOUTHERN TROF
WILL STILL BE MOVING TOWARD NM. THE SLOWER EC HANGS ON TO A FEW
SHWRS OVER THE SRN MTNS...WHILE THE GFS BEGINS TO SPREAD PCPN ACROSS
THE NRN PART OF THE CWA IN RESPONSE TO APPROACHING STRONG COLD
FRONT. WILL COMPROMISE FOR NOW WITH SCATTERED POPS MOST MTN
LOCATIONS. STRONG COOLING ALOFT IS NOTED IN THE GFS WHICH PUSHES
THE COLD FRONT THROUGH THE ENTIRE CWA BY EARLY MONDAY MORNING. BY
EARLY MONDAY MORNING COLD CORE WILL BE OVER WRN CO WITH THE COLDEST
TEMPS OF THE SEASON SO FAR (H5 TEMP -33C).
THE COLD UPPER TROF WILL BEGIN TO SHIFT EASTWARD MONDAY WHILE RIDGE
TRIES TO BUILD OVER THE GRT BASIN. THE NEXT ARCTIC SHRT WV WILL
FLATTEN THE FLOW TUE/WED BEFORE DROPPING SOUTHWARD INTO THE GRT BASIN
THURSDAY WHICH PROMISES ANOTHER SHOT OF WINTRY WX AND COLD
TEMPERATURES.
&&
.AVIATION /FOR 00Z TAF ISSUANCE/...
MOSTLY VFR CONDITIONS ARE EXPECTED THIS EVENING AT ALL THE TAF
SITES...LASTING THROUGH FRIDAY MORNING. HOWEVER PILOTS FLYING IN
SOUTHWESTERN COLORADO AND SOUTHEAST UTAH WILL EXPERIENCE MTN OBSC
AND MVFR VSBY IN LIGHT SNOW.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
UT...NONE.
&&
$$
SHORT TERM...JAD
LONG TERM....MC
AVIATION.....TGJT
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
820 PM EST Fri Dec 2 2011
.SYNOPSIS...
AT UPPER LEVELS...
The large scale longwave pattern is highlighted by a deep positively
tilted trough over Wrn states with 550dm closed low over AZ...a deep
layer ridge over Cntrl states...SE region and adjacent Wrn Atlc, and
a trough over NE states. RUC shows a deep water vapor return from
the Gulf of Mex along wrn periphery of ridge along Wrn Gulf but
clouds should remain west of local area. All this translates to
continued fair, dry and cool weather over NE Gulf region. This
reflected in area 00Z RAOBS. i.e. TAE with 0.17 inch PWAT with light
ENE flow below and WNW winds above H6.
During the next 24 hrs, AZ low will deamplify as it accelerates newd
thru NM...CNTRL Plains reaching Upper MS Valley/Upper Great Lakes
early Sunday. Parent trough will deepen EWD. This allows for the
building of downstream ridge from Yucatan NEWD thru Gulf of Mex and
into N FL and SE region with rising heights and warming temps.
AT LOWER LEVELS...
High pressure centered over Srn Great Lakes dominates SE region
maintaining a NE flow. Looking upstream, main feature is low over
Cntrl Canada with trailing front swwd over Plains to low over NEB.
By early sat...low shifts newd shift front ewd now extending from
Upper Great Lakes swwd thru MO and W TX by early sat.
A warming trend is forecast for the rest of the weekend as the high
moves into New England overnight and drifts off coast during Sat and
Sun before ridging SSW down Ern seaboard and into SE coastal area
tightening local gradients and veering winds to produce breezy
northeast to east flow. This will also bring some low level moisture
WWD from the Atlc.
&&
.NEAR TERM...(Rest of Tonight into early Saturday)
High pressure remains the dominant feature in the local weather
pattern. The ridge is forecast to shift more NE of the area
overnight, which may allow just enough of a light breeze at times to
keep temperatures from falling as much as last night. As a result,
we are not expecting a widespread freeze, although with inland dew
points in the low to mid 30s and likely light winds and clear skies,
areas of frost are still likely in the typically colder locations
away from urban areas.
&&
.AVIATION...VFR conditions will prevail. Winds will shift to
easterly tomorrow as the high pressure area nears the Mid Atlantic
Coast.
&&
.MARINE...The persistence of the high pressure ridge situated along
the U.S. eastern seaboard will maintain a rather tight pressure
gradient over the coastal waters through Monday. At 8 PM EST
offshore buoys already around 15 knots and should increase to SCEC
levels before midnight. So exercise caution has been headlined for
rest of tonight for all but the Apalachee Bay. Winds will peak
perhaps late Saturday night or early Sunday with marginal advisory
winds (around 20 KT) over portions of our coastal waters. Otherwise,
winds will continue to straddle the exercise caution threshold
through Saturday evening.
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
AL...None.
GA...None.
FL...None.
GM...None.
&&
$$
BLOCK/GODSEY
AREA FORECAST DISCUSSION...UPDATED
NWS TALLAHASSEE FL
645 AM EST Thu Dec 01 2011
UPDATED FOR 12Z TAF ISSUANCE
.SYNOPSIS...
07Z water vapor and H4 RUC analysis shows an active upper level
pattern across the CONUS this morning. Sharp troughing covers the
inter-mountain west with a potent shortwave at its base digging
southward over CA/NV. This energy is progged to close off over the
next several hours and stall. Further downstream the flow leaving
the southwestern states ridges northward across the Central
Plains/Middle and lower MS valley. Finally we find troughing about
to exit off the Atlantic seaboard. The base of this trough contains
a fairly sharp/potent shortwave that is just now exiting east of our
forecast area. Large scale subsidence on the backside of this
impulse is working to continue drying our our atmospheric column,
and will help contribute to abundant sunshine for our Thursday. The
KTLH 00Z sounding profile already showed an impressively low PW
values of 0.31" (only about 33% of climo for early December). With
the ongoing subsidence...would anticipate the 12Z profile to be even
lower. In fact both the GFS and NAM prog PW values down as low as
0.2" by sunrise.
At the surface,
1025mb ridge of high pressure is centered from the TN Valley to the
MS/AL border region. The influence of this ridge extends into our
forecast area with a weak gradient now in place. This weak gradient
has allowed winds to go very light/calm early this morning and
boundary layer decoupling appears to have already occurred at many
locations. Good radiational cooling within the decoupled layer has
allowed many stations to reach the freezing mark or lower this
morning. At this time the freeze warning appears on track and do not
anticipate making any significant changes to the forecast through
sunrise.
&&
.SHORT TERM (TODAY THROUGH SATURDAY)...
Today,
Pleasant day on tap after a cold start. Heights will rise over the
region in the wake of the departing shortwave trough. The rising
heights along with the building surface high building will lead to
stacked ridging dominating our weather by the end of the day. The
weak low level gradient and near solar minimum sun angle will not
lead to efficient mixing today. High temperatures will again end up
below normal despite abundant sunshine. Temperatures will struggle
into the lower 60s by mid-afternoon across a majority of the area,
with a few middle 60s down toward Perry, Mayo, and Cross City.
Tonight,
Clear skies, dry low levels, and the surface ridge axis still in
close proximity will allow for another fairly cold night. It does
not appear likely that we will see the areal coverage of freezing or
sub-freezing temperatures that are occurring this morning, nor does
it appear that we will see the durations of freezing temperatures.
Minimum temperature grids will show widespread lower to middle 30s
away from the immediate coast. These temperatures combined with the
light winds and small dewpoint depressions should still lead to
areas of frost development. The forecast will show this frost
potential for all areas expected to reach 35 degrees or lower.
Normally colder spots are forecast to briefly drop below freezing
(30-32F) around sunrise, however the overall coverage at this time
is not anticipated to warrant another freeze watch/warning event.
Friday Through Saturday,
Stacked ridging will remain in control of our weather providing dry,
seasonable, and slowly warming conditions into the first half of the
upcoming weekend. Temperatures Friday will rebound upward several
degrees from Thursday`s highs. Current grids will show mainly middle
to upper 60s, with lower 70s over the SE Big Bend Zones. Very dry
atmosphere will keep our skies sunny.
Strong high pressure will redevelop and build down the eastern
seaboard later Friday and Friday night. ECMWF/GFS both show surface
pressures with this high reaching 1036-1038mb over the mid-Atlantic
region. The effect for our region will be a significant tightening
of the gradient and resulting easterly flow. This easterly flow will
begin to transport low level Atlantic moisture back into the region.
Due to the tighter gradient and increased moisture, do not
anticipate the potential for freezing temps or likely even any frost
Friday night. It will still be cool, but the coldest inland temps
currently in the grids show mid/upper 30s. Temps warmer still will
be experienced along the coast from Wakulla County westward due to
the easterly/ESE flow.
More of the same for Saturday with perhaps a few-sct afternoon cu
field. More efficient mixing due to the tighter gradient will allow
temps to climb toward the lower 70s across much of the area.
&&
.LONG TERM (SUNDAY THROUGH NEXT THURSDAY)...
The Guidance is in decent agreement through Sunday night before
significant differences begin to arise. Through Sunday night, a
ridge will be in place over the Southeastern states, with dry
conditions and temperatures back near climo. A strong surface high
over New England will keep northeast flow in place across the region
Sunday and prevent temperatures from warming more significantly.
This high shifts well east by Monday, allowing for a more
substantial warm-up.
Significant model differences are evident by Monday through
Wednesday with the deep longwave trough over the central states. The
CMC and GFS are more progressive with the system and bring the
surface front through the region late Monday or early Tuesday. The
ECMWF and UKMET cutoff the tail of the trough leading to a much
slower progression, and a frontal passage Tuesday night or early
Wednesday. With significant uncertainty, have decided to take a
compromise of all the guidance, leading to a frontal passage on
Tuesday. A band of showers is expected with the front. However, the
bulk of the dynamics and lift are expected to pull northeast of the
area, with coverage on the decrease as the front crosses the region.
A much cooler airmass will spill into the region in the wake of the
front.
&&
.MARINE...
A ridge of high pressure will slide to the north of the forecast
waters through Friday. Northerly flow will come around to Northeast
and then east through this time. Cautionary level winds may briefly
decrease below headline criteria later this morning and into the
afternoon, but will increase back to cautionary levels tonight. The
gradient will tighten Friday night into Saturday as a new and
stronger area of high pressure builds down the eastern seaboard.
This tighter gradient will lead to a prolonged period of cautionary
to advisory level easterly flow through the upcoming weekend. The
next cold front will then approach from the west during the early
portion of next week.
&&
.AVIATION (through Friday 12z)...VFR conditions expected to prevail
through the forecast period.
&&
.FIRE WEATHER...
A dry airmass will remain in place over the region through Friday.
Cool temperatures will prevent RH values from dropping to critical
levels today. Slightly warmer temperatures on Friday will allow for
sub-35 percent RH across the Florida zones. However, ERC values are
expected to remain below 35. Therefore, no Fire Weather Watch is
planned at this time.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 63 33 68 39 72 / 0 0 0 0 0
Panama City 62 40 67 47 68 / 0 0 0 0 0
Dothan 61 34 67 39 70 / 0 0 0 0 0
Albany 62 32 67 36 70 / 0 0 0 0 0
Valdosta 63 33 67 39 72 / 0 0 0 0 0
Cross City 67 36 71 41 75 / 0 0 0 0 0
Apalachicola 61 40 65 46 69 / 0 0 0 0 0
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
AL...Freeze Warning until 8 AM CST this morning for Coffee-Dale-
Geneva-Henry-Houston.
GA...Freeze Warning until 9 AM EST this morning for Baker-Ben Hill-
Berrien-Brooks-Calhoun-Clay-Colquitt-Cook-Decatur-Dougherty-
Early-Grady-Irwin-Lanier-Lee-Lowndes-Miller-Mitchell-
Quitman-Randolph-Seminole-Terrell-Thomas-Tift-Turner-Worth.
FL...Freeze Warning until 9 AM EST /8 AM CST/ this morning for
Calhoun-Central Walton-Coastal Bay-Gadsden-Holmes-Inland
Bay-Inland Dixie-Inland Franklin-Inland Gulf-Inland
Jefferson-Inland Taylor-Inland Wakulla-Inland Walton-
Jackson-Lafayette-Leon-Liberty-Madison-South Walton-
Washington.
GM...None.
&&
$$
SYNOPSIS/SHORT TERM/MARINE...MROCZKA
LONG TERM/AVIATION/FIRE WX...CAMP
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
305 AM EST Thu Dec 01 2011
.SYNOPSIS...
07Z water vapor and H4 RUC analysis shows an active upper level
pattern across the CONUS this morning. Sharp troughing covers the
inter-mountain west with a potent shortwave at its base digging
southward over CA/NV. This energy is progged to close off over the
next several hours and stall. Further downstream the flow leaving
the southwestern states ridges northward across the Central
Plains/Middle and lower MS valley. Finally we find troughing about
to exit off the Atlantic seaboard. The base of this trough contains
a fairly sharp/potent shortwave that is just now exiting east of our
forecast area. Large scale subsidence on the backside of this
impulse is working to continue drying our our atmospheric column,
and will help contribute to abundant sunshine for our Thursday. The
KTLH 00Z sounding profile already showed an impressively low PW
values of 0.31" (only about 33% of climo for early December). With
the ongoing subsidence...would anticipate the 12Z profile to be even
lower. In fact both the GFS and NAM prog PW values down as low as
0.2" by sunrise.
At the surface,
1025mb ridge of high pressure is centered from the TN Valley to the
MS/AL border region. The influence of this ridge extends into our
forecast area with a weak gradient now in place. This weak gradient
has allowed winds to go very light/calm early this morning and
boundary layer decoupling appears to have already occurred at many
locations. Good radiational cooling within the decoupled layer has
allowed many stations to reach the freezing mark or lower this
morning. At this time the freeze warning appears on track and do not
anticipate making any significant changes to the forecast through
sunrise.
&&
.SHORT TERM (TODAY THROUGH SATURDAY)...
Today,
Pleasant day on tap after a cold start. Heights will rise over the
region in the wake of the departing shortwave trough. The rising
heights along with the building surface high building will lead to
stacked ridging dominating our weather by the end of the day. The
weak low level gradient and near solar minimum sun angle will not
lead to efficient mixing today. High temperatures will again end up
below normal despite abundant sunshine. Temperatures will struggle
into the lower 60s by mid-afternoon across a majority of the area,
with a few middle 60s down toward Perry, Mayo, and Cross City.
Tonight,
Clear skies, dry low levels, and the surface ridge axis still in
close proximity will allow for another fairly cold night. It does
not appear likely that we will see the areal coverage of freezing or
sub-freezing temperatures that are occurring this morning, nor does
it appear that we will see the durations of freezing temperatures.
Minimum temperature grids will show widespread lower to middle 30s
away from the immediate coast. These temperatures combined with the
light winds and small dewpoint depressions should still lead to
areas of frost development. The forecast will show this frost
potential for all areas expected to reach 35 degrees or lower.
Normally colder spots are forecast to briefly drop below freezing
(30-32F) around sunrise, however the overall coverage at this time
is not anticipated to warrant another freeze watch/warning event.
Friday Through Saturday,
Stacked ridging will remain in control of our weather providing dry,
seasonable, and slowly warming conditions into the first half of the
upcoming weekend. Temperatures Friday will rebound upward several
degrees from Thursday`s highs. Current grids will show mainly middle
to upper 60s, with lower 70s over the SE Big Bend Zones. Very dry
atmosphere will keep our skies sunny.
Strong high pressure will redevelop and build down the eastern
seaboard later Friday and Friday night. ECMWF/GFS both show surface
pressures with this high reaching 1036-1038mb over the mid-Atlantic
region. The effect for our region will be a significant tightening
of the gradient and resulting easterly flow. This easterly flow will
begin to transport low level Atlantic moisture back into the region.
Due to the tighter gradient and increased moisture, do not
anticipate the potential for freezing temps or likely even any frost
Friday night. It will still be cool, but the coldest inland temps
currently in the grids show mid/upper 30s. Temps warmer still will
be experienced along the coast from Wakulla County westward due to
the easterly/ESE flow.
More of the same for Saturday with perhaps a few-sct afternoon cu
field. More efficient mixing due to the tighter gradient will allow
temps to climb toward the lower 70s across much of the area.
&&
.LONG TERM (SUNDAY THROUGH NEXT THURSDAY)...
The Guidance is in decent agreement through Sunday night before
significant differences begin to arise. Through Sunday night, a
ridge will be in place over the Southeastern states, with dry
conditions and temperatures back near climo. A strong surface high
over New England will keep northeast flow in place across the region
Sunday and prevent temperatures from warming more significantly.
This high shifts well east by Monday, allowing for a more
substantial warm-up.
Significant model differences are evident by Monday through
Wednesday with the deep longwave trough over the central states. The
CMC and GFS are more progressive with the system and bring the
surface front through the region late Monday or early Tuesday. The
ECMWF and UKMET cutoff the tail of the trough leading to a much
slower progression, and a frontal passage Tuesday night or early
Wednesday. With significant uncertainty, have decided to take a
compromise of all the guidance, leading to a frontal passage on
Tuesday. A band of showers is expected with the front. However, the
bulk of the dynamics and lift are expected to pull northeast of the
area, with coverage on the decrease as the front crosses the region.
A much cooler airmass will spill into the region in the wake of the
front.
&&
.MARINE...
A ridge of high pressure will slide to the north of the forecast
waters through Friday. Northerly flow will come around to Northeast
and then east through this time. Cautionary level winds may briefly
decrease below headline criteria later this morning and into the
afternoon, but will increase back to cautionary levels tonight. The
gradient will tighten Friday night into Saturday as a new and
stronger area of high pressure builds down the eastern seaboard.
This tighter gradient will lead to a prolonged period of cautionary
to advisory level easterly flow through the upcoming weekend. The
next cold front will then approach from the west during the early
portion of next week.
&&
.AVIATION (through Friday 06z)...With high pressure building into
the region, VFR conditions and light winds are expected to prevail
through the forecast period. May see a brief period of MVFR VSBY at
KDHN this morning, as indicated by some of the numerical guidance.
However, VSBY should stay at or above 5SM.
&&
.FIRE WEATHER...
A dry airmass will remain in place over the region through Friday.
Cool temperatures will prevent RH values from dropping to critical
levels today. Slightly warmer temperatures on Friday will allow for
sub-35 percent RH across the Florida zones. However, ERC values are
expected to remain below 35. Therefore, no Fire Weather Watch is
planned at this time.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 63 33 68 39 72 / 0 0 0 0 0
Panama City 62 40 67 47 68 / 0 0 0 0 0
Dothan 61 34 67 39 70 / 0 0 0 0 0
Albany 62 32 67 36 70 / 0 0 0 0 0
Valdosta 63 33 67 39 72 / 0 0 0 0 0
Cross City 67 36 71 41 75 / 0 0 0 0 0
Apalachicola 61 40 65 46 69 / 0 0 0 0 0
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
AL...Freeze Warning until 8 AM CST this morning for Coffee-Dale-
Geneva-Henry-Houston.
GA...Freeze Warning until 9 AM EST this morning for Baker-Ben Hill-
Berrien-Brooks-Calhoun-Clay-Colquitt-Cook-Decatur-Dougherty-
Early-Grady-Irwin-Lanier-Lee-Lowndes-Miller-Mitchell-
Quitman-Randolph-Seminole-Terrell-Thomas-Tift-Turner-Worth.
FL...Freeze Warning until 9 AM EST /8 AM CST/ this morning for
Calhoun-Central Walton-Coastal Bay-Gadsden-Holmes-Inland
Bay-Inland Dixie-Inland Franklin-Inland Gulf-Inland
Jefferson-Inland Taylor-Inland Wakulla-Inland Walton-
Jackson-Lafayette-Leon-Liberty-Madison-South Walton-
Washington.
GM...None.
&&
$$
SYNOPSIS/SHORT TERM/MARINE...MROCZKA
LONG TERM/AVIATION/FIRE WX...CAMP
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1140 PM CST WED NOV 30 2011
...UPDATE TO AVIATION...
.DISCUSSION...
SHORT RANGE FORECAST (TONIGHT AND THURSDAY)...
20Z WATER VAPOR IMAGERY AND ASSOCIATED 500 MB RUC ANALYSIS SHOWS A
MID/UPPER LEVEL TROUGH OVER THE APPALACHIAN MOUNTAINS...WITH ANOTHER
H5 LOW DIVING SOUTHWARD THROUGH THE NORTHERN ROCKIES. BETWEEN THE
TWO TROUGHS IS A FLATTENED UPPER RIDGE OVER THE CENTRAL PLAINS WHICH
HAS BROUGHT FAIR CONDITIONS TO THE AREA. SOUTHERLY FLOW ALONG THE
EASTERN EDGE OF A DEEPENING SURFACE TROUGH ADVECTED WARM AIR INTO
NORTHEAST KANSAS...ALLOWING TEMPS TO REACH THE MID 50S ACROSS MUCH
OF THE AREA. EXPECT THE SURFACE TROUGH TO PUSH SOUTHEASTWARD AHEAD
OF AN ADVANCING SURFACE RIDGE...WHICH WILL BRING A COLD FRONT
THROUGH THE AREA BY MID DAY ON THURSDAY. EXPECT COOLER/DRYER AIR TO
MOVE IN BEHIND THE COLD FRONT FOR THURSDAY...ESPECIALLY FOR AREAS
ACROSS NORTH CENTRAL KANSAS WHICH WILL SEE THE FRONTAL PASSAGE
BEFORE PEAK HEATING. AREAS OF EASTERN KANSAS MAY SEE ANOTHER MILD
DAY AS SOUTHERLY FLOW SHOULD PERSIST THROUGH MUCH OF THE EARLY
AFTERNOON BEFORE THE FRONTAL PASSAGE IN THE EARLY EVENING. EXPECT
STRATUS TO BUILD IN BEHIND THE FRONT WHICH COULD POSSIBLY BRING SOME
SCATTERED SPRINKLES OR POSSIBLY SOME SNOW FLURRIES TO AREAS OF NORTH
CENTRAL KANSAS ON THURSDAY.
LEIGHTON
LONG TERM...THU NIGHT THROUGH NEXT WEDS.
FCST FOCUS REMAINS ON THE EVOLUTION OF STORM SYSTEM FRI INTO SAT.
RECENT MODEL GUIDANCE AND TRENDS CONTINUE TO SUGGEST A SLOWER
TRACK THAN THAT INDICATED BY THE NAM. GFS/ECMWF ARE THE FAVORED
MODELS FOR THIS FCST.
INITIAL MODIFIED POLAR AIRMASS WILL SETTLE INTO THE AREA THU
NIGHT WITH LIGHT WINDS AND SEASONABLY COLD TEMPS. BY FRI
AM...SOUTHERLY SFC WINDS WILL DEVELOP AS THE WESTERN U.S. LONGWAVE
TROUGH BEGINS TO BECOME PROGRESSIVE. LIFT WILL INCREASE THROUGH
THE DAY WITH SATURATION AND PRECIP DEVELOPMENT EXPECTED BY FRI
NIGHT. THERMAL PROFILES SUGGEST MAINLY RAIN EXCEPT FOR THE
NORTHWEST THIRD OF THE CWA WHERE DEPENDING ON THE WET BULB TEMPS
THERE MAY BE A RISK FOR FREEZING RAIN. GFS RAW MODEL NEAR SFC
TEMPS ARE WARMER THAN THE NUMERICAL MODEL GUIDANCE WHICH SUGGESTS
LOWS IN THE UPPER 20S TO LOWER 30S ACROSS THE NW THIRD SO
CONFIDENCE IN ICE THREAT REMAINS LOW AT THIS TIME. RIGHT NOW AREAS
ROUGHLY FROM ABILENE TO SENECA AND NW COULD SEE FREEZING PRECIP
FRI NIGHT. GFS CONTINUES TO WARM BOUNDARY LAYER TEMPS UP EARLY SAT
SUCH THAT ANY FZRA/ICE RISK SHOULD DECREASE HOWEVER WIDESPREAD
RAIN...SOME HEAVY SHOULD PERSIST ACROSS THE AREA AS THE UPPER
TROUGH MOVES THROUGH THE AREA AND THE SFC LOW TRACKS ACROSS
EASTERN KS. PRECIP SHOULD MIX WITH OR CHANGE TO SLEET OR SNOW FROM
WEST TO EAST BY LATER SAT/SAT NIGHT AS COLDER AIR ARRIVES ON THE
BACK SIDE OF THE SYSTEM. HOWEVER GFS ALSO SHOWS A DRY SLOT LATER
SAT AFTERNOON WHICH COULD BRING A BREAK IN THE PRECIP AND WOULD
ALSO LIMIT THE SNOW THREAT ACROSS NORTH-CENTRAL KS.
ALL IN ALL...LOOK FOR ANOTHER ROUND OF WIDESPREAD HEAVY RAINS OF 1
TO 2.5 INCHES FRI NIGHT INTO SAT WITH WHAT APPEARS TO BE A LOW RISK
FOR FREEZING PRECIP FRI NIGHT ACROSS PARTS OF THE AREA.
THE PATTERN LOOKS QUITE ACTIVE FOR THE REGION INTO NEXT WEEK WITH
ADDITIONAL POLAR COLD FRONTS EXPECTED TO DRIVE SOUTHWARD THROUGH
THE PLAINS. THE ACTUAL LONGWAVE TROUGH AXIS MAY NOT PASS THROUGH
THE REGION UNTIL MID WEEK SO CLOUDS/SOME LOW PRECIP CHCS MAY
LINGER ACROSS SOUTHERN KS BUT IT LOOKS DRY BUT COLD ACROSS NE KS.
CO
&&
.AVIATION...
VFR CONDITIONS TO CONTINUE THROUGH AT LEAST 23Z TODAY...THEN LOWER
STRATUS MAY MAKE A RUN AT THE TERMINAL LOCATIONS. MODELS BRING A
NARROW STRIP OF MVFR CIGS INTO AREA AFTER 23Z AND CONFIDENCE NOT
HIGH ENOUGH AT THIS TIME TO GO WITH A PROLONGED PERIOD OF MVFR
CIGS AFTER 02/00Z. WINDS SHIFT TO THE NORTH IN THE 14Z-16Z PERIOD
TODAY...THEN REMAIN NEAR 10 KTS THROUGH THE REST OF THE PERIOD.
53
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
THE PREVIOUS SHORT TERM FORECAST DISCUSSION FOLLOWS...
/TODAY THROUGH SATURDAY/
EARLY THIS MORNING...UPPER LEVEL AND SFC RIDGING WERE THE DOMINANT
WEATHER FEATURES ACROSS THE REGION. THE UPPER LEVEL RIDGING WAS
CENTERED OVER THE GULF OF MEXICO REGION AND EXTENDED NORTH INTO THE MID
MS AND TN VALLEYS...WITH A DEPARTING TROUGH TO ITS EAST AND A CLOSED
LOW OVER THE SIERRA NEVADA/SOUTHWESTERN US. MEANWHILE...A SHORTWAVE
WAS OVER THE NORTHERN PLAINS AND NORTHERN ROCKIES.
TODAY AND TONIGHT...THE TROUGH OFF THE EASTERN SEABOARD WILL DEPART
FURTHER TO THE EAST WITH THE WESTERN CONUS CLOSED LOW DROPPING INTO
THE DESERT SW AND HEIGHTS INCREASE TO ITS NORTH DUE TO UPPER LEVEL
RIDGING BUILDING EAST FROM THE PACIFIC. MEANWHILE THE SHORTWAVE
NOW MOVING THROUGH THE PLAINS/NORTHERN ROCKIES WILL MOVE EAST RATHER
QUICKLY INTO THE GREAT LAKES BY THIS EVENING AND REACHING THE EASTERN
GREAT LAKES AND LOWER OH VALLEY BY DAWN ON FRIDAY. THIS SYSTEM WILL
CONTINUE PASSING BY TO OUR NORTH ON FRIDAY WITH HEIGHTS BRIEFLY INCREASING
FROM THE TN VALLEY NORTH INTO THE GREAT LAKES FROM FRI INTO FRIDAY
NIGHT IN ITS WAKE. AT THE SAME TIME...A SHORTWAVE WILL ENTER THE
NORTHERN ROCKIES AND PLAINS FROM FRI INTO FRIDAY NIGHT WHILE THE SW
US CLOSED LOW MEANDERS INTO THE FOUR CORNERS REGION. BY DAWN ON
SAT...A RATHER AMPLIFIED RIDGE IS EXPECTED WITH THE AXIS EXTENDING
FROM THE YUCATAN NORTH INTO THE MID ATLANTIC AND NORTHEAST...WITH A
MEAN TROUGH FROM CENTRAL CANADA WSW INTO THE SOUTHWESTERN US AND
SOUTHERN ROCKIES...THOUGH INDIVIDUAL SHORTWAVES ARE NOT EXPECTED TO
PHASED. HEIGHTS ARE PROGGED TO FALL OVER THE MS VALLEY AND LOWER OH
VALLEY LATE IN THE PERIOD AS THE TROUGH BEGINS TO SHIFT EAST.
HOWEVER...A DRY AIRMASS IS EXPECTED BELOW 500 MB FROM THE INFLUENCE
OF THE RIDGING JUST TO OUR EAST.
OTHER THAN SOME PATCHY VALLEY THROUGH AROUND DAWN OVER PORTIONS OF
THE CUMBERLAND...KENTUCKY AND BIG SANDY BASINS...THE RATHER SHOULD BE
RATHER UNEVENTFUL THROUGH THE PERIOD. THE DRY AIRMASS IN PLACE WILL
ONLY LEAD TO OCCASIONAL INCREASES IN HIGH CLOUDS WITH UPPER LEVEL
DISTURBANCES PASSING BY TO OUR NORTH THIS AM THROUGH EARLY AFTERNOON
AND AGAIN ON FRIDAY THROUGH FRIDAY NIGHT. A FEW MID CLOUDS MAY ALSO
PASS OVERHEAD FROM FRI INTO FRI NIGHT. ONLY SOME HIGH CLOUDS ARE
ANTICIPATED ON SAT AND THEY MAY BEGIN TO THICKEN AND LOWER LATE IN
THE PERIOD. OVERALL...THIS IS MAINLY JUST A TEMP...SKY AND DEWPOINT
FORECAST THROUGH THE PERIOD.
RIDGE/VALLEY TEMPS SPLITS SHOULD OCCUR THE NEXT COUPLE OF NIGHTS WITH
GRADUALLY MODERATING DAYTIME HIGHS THROUGH SAT. WITH MIXING TODAY...
VALLEY FOG IS NOT EXPECTED ON THU NIGHT OR FRI NIGHT.
.LONG TERM.../SATURDAY NIGHT THROUGH WEDNESDAY/
THE LATEST ROUND OF MODELS REMAINS IN FAIRLY GOOD AGREEMENT THROUGH
THE FIRST HALF OF THE PERIOD...THEN BEGINS TO DIVERGE WITH THE
DETAILS SURROUNDING A COLD FRONT APPROACHING THE OHIO VALLEY EARLY
NEXT WEEK. OVERALL...THE MEDIUM RANGE GUIDANCE CONTINUES TO SUPPORT
THE IDEA OF SHOWERS ASSOCIATED WITH THE FRONT MOVING INTO THE AREA
ON SUNDAY...KICKING OFF AN EXTENDED PERIOD OF RAIN THAT LOOKS TO
CONTINUE THROUGH AT LEAST TUESDAY AND POSSIBLY INTO TUESDAY NIGHT.
HOWEVER THE QUESTION REMAINS AS TO HOW FAST THE COLDER AIR WILL
BEGIN TO ARRIVE AND AT WHAT POINT WILL THE POTENTIAL FOR SNOW BECOME
AN ISSUE.
THE 01.00Z GEM LIES AT THE FASTER END OF THE SPECTRUM...BRINGING THE
COLDER AIRMASS INTO THE OHIO VALLEY AND ERN KY BY MONDAY NIGHT...BUT
WITH NO SUPPORT FROM THE OTHER MODELS HAVE DISCOUNTED THIS SOLUTION.
MEANWHILE THE 00Z ECMWF CONTINUES TO REPRESENT THE SLOWER END OF THE
SPECTRUM...HOLDING BACK THE ARRIVAL OF THE COLDER AIR ALOFT UNTIL
LATE WEDNESDAY...WHILE THE 00Z GFS REPRESENTS SOMEWHAT OF A MIDDLE
GROUND COMPROMISE...BRINGING THE COLDER AIR INTO THE REGION LATE
MONDAY NIGHT INTO TUESDAY. THE DISPARITY IN TIMING AT THIS POINT
LEADS TO A LOWER CONFIDENCE IN THE P TYPE AFTER MONDAY...AND WILL
CONTINUE TO ADVERTISE A MIXED BAG FROM MONDAY NIGHT ONWARD THROUGH
THE REMAINDER OF THE EVENT.
TEMPERATURES WILL ULTIMATELY BE DEPENDENT ON HOW EVENTS UNFOLD NEXT
WEEK...BUT GENERALLY FOLLOWED THE ALL BLEND CONSENSUS WITH A FEW
ADJUSTMENTS TO HIGHS ON MONDAY AND TUESDAY TO ACCOUNT FOR THE
EXPECTED PRECIPITATION AND TO LINE UP A LITTLE BETTER WITH THE
NEIGHBORS. THIS RESULTED IN HIGHS EARLY IN THE PERIOD RUNNING ABOVE
NORMAL FOR THE BEGINNING OF DECEMBER BEFORE TOPPING OUT IN THE 40S
BEHIND THE FRONT LATER IN THE PERIOD...WITH OVERNIGHT LOWS FOLLOWING
A SIMILAR TREND.
&&
.AVIATION.../18Z TO 18Z/...UPDATED
A SFC RIDGE OF HIGH PRESSURE SETTLING ACROSS THE OH AND TN VALLEY
WILL REMAIN IN PLACE OVER THE REGION DURING THE PERIOD AND BRING
VFR CONDITIONS THROUGH THE ENTIRE PERIOD. NO FOG IS FORECAST FOR THE
TAF STATIONS FOR TOMORROW.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...JP/JJ
LONG TERM....MB
AVIATION...JJ
AREA FORECAST DISCUSSION
NWS GRAY ME
920 PM EST FRI DEC 2 2011
.SYNOPSIS...
A COLD FRONT WILL CROSS THE AREA AND PUSH OFFSHORE TONIGHT FOLLOWED
BY HIGH PRESSURE. HIGH PRESSURE WILL CREST OVER THE REGION ON
SATURDAY AND SHIFT OFFSHORE SATURDAY NIGHT. A COLD FRONT WILL
SHIFT INTO WESTERN NEW ENGLAND ON MONDAY AND WILL STALL. WEAK LOW
PRESSURE MOVING OUT OF THE THE SOUTHEASTERN U.S. WILL TRACK
NORTHEAST ALONG THIS BOUNDARY MONDAY NIGHT AND TUESDAY AS THE
FRONT EDGES INTO SOUTHERN NEW ENGLAND AND COASTAL MAINE. LOW
PRESSURE WILL MOVE NORTHEAST THROUGH SOUTHERN NEW ENGLAND AND THE
GULF OF MAINE ON WEDNESDAY. A WEAK RIDGE OF HIGH PRESSURE WILL
BUILD IN BEHIND THE FRONT WEDNESDAY NIGHT AND THURSDAY. ANOTHER
COLD FRONT WILL CROSS THE AREA THURSDAY NIGHT AND WILL MOVE
OFFSHORE FRIDAY.
&&
.NEAR TERM /THROUGH SATURDAY/...
UPDATE...REMAINING SHSN/RA ARE EXITING THE MIDCOAST...WITH
LINGERING SHSN IN THE MTNS OF NRN NH/ME DUE TO TERRAIN ENHANCEMENT
OF LIFT. FCST PROBLEM IS LINGERING LLVL MOISTURE AND STRATUS DECK
TRAPPED BENEATH DEVELOPING SUBSIDENCE INVERSION. BACK EDGE OF
STRATUS ROUGHLY BISECTING CNTRL NY AND EXTENDING NEWD INTO SRN
QUEBEC. THIS BACK EDGE WILL ADVANCE SEWD WHILE ERODING SLIGHTLY AS
ATMOSPHERE CONTINUES TO DRY OUT. HOWEVER...THIS WILL KEEP MUCH OF
THE CWFA UNDER THE CLOUDS FOR THE NIGHT. SLGT DOWNSLOPE FLOW WILL
PROBABLY SCT OUT THE COASTAL PLAIN BEFORE THE MTNS...WHERE CLOUD
COVER MAY LINGER FOR MUCH OF THE NGT. ATTM...MODELS ARE HANDLING
THE LLVL MOISTURE POORLY...BUT THE RUC HAS AN IDEA...WITH 2D MAPS
AND BUFKIT SOUNDINGS SHOWING A THINNING CLOUD DECK AROUND 09-12Z.
HAVE TRENDED IN THAT DIRECTION...ALONG WITH RAISING MIN TEMPS A
FEW DEGREES.
&&
.SHORT TERM /SATURDAY NIGHT/...
DEEP LAYER RIDGING WILL BE THE MAIN STORY SATURDAY AND SATURDAY
NIGHT. THIS WILL MEAN MOSTLY CLEAR SKIES AND DRY WEATHER. TEMPS
WILL BE RIGHT AROUND NORMAL.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
HIGH PRESSURE MOVING EAST THROUGH THE MARITIMES ON SUNDAY WILL
PROVIDE ONE MORE PARTLY TO MOSTLY SUNNY DAY. THERE WILL BE SOME HIGH
CLOUDINESS AROUND ESPECIALLY IN THE AFTERNOON BUT TEMPERATURES
SHOULD AVERAGE OUT ABOVE NORMAL. EXPECT HIGHS TO RANGE THROUGH THE
40S IN THE NORTH AND UPPER 40S TO LOWER 50S IN THE SOUTH.
INCREASING CLOUDS SUNDAY NIGHT AS THE COLD FRONT APPROACHES FROM THE
WEST. VARIABLE CLOUDINESS SHOULD PREVAIL THROUGH THE NIGHT WHICH
WILL HELP KEEP TEMPS UP SOMEWHAT. EXPECT LOWS FROM THE MID 30S TO
LOWER 40S ACROSS THE REGION.
COLD FRONT WILL SLOW TO A CRAWL AS IT ENTERS WESTERN NEW ENGLAND ON
MONDAY. SKIES WILL BECOME MOSTLY CLOUDY WITH A SLIGHT CHANCE OF
SHOWERS IN THE MOUNTAINS THROUGH LATE AFTERNOON. ELSEWHERE PARTLY
SUNNY SKIES WILL PREVAIL. HIGH TEMPERATURES WILL RANGE FROM THE MID
40S IN THE NORTH TO MID 50S IN THE SOUTH.
BETTER CHANCE FOR RAIN OR SNOW SHOWERS MONDAY NIGHT IN THE NORTH AS
WEAK LOW PRESSURE TRACKS NORTHEAST OUT OF THE SOUTHEASTERN U.S. AND
WEAK OVER-RUNNING SETS UP OVER THE AREA.
EXTENDED PERIOD OF WET WEATHER LOOKING MORE CERTAIN FOR TUESDAY AND
EARLY WEDNESDAY AS THE FRONT SLOWLY EDGES EASTWARD AND SEVERAL AREAS
OF WEAK LOW PRESSURE TRACK NORTHEAST ALONG IT. MODELS STILL NOT IN
AGREEMENT ON HOW FAR EAST THIS BOUNDARY PUSHES AS LOW PRESSURE
PASSES THROUGH THE AREA LATE TUESDAY THROUGH WEDNESDAY. AT THIS
POINT LOOKING LIKE ENOUGH WARM AIR REMAINS OVER THE FORECAST AREA TO
KEEP THE BULK OF PRECIPITATION IN THE FORM OF RAIN ALTHOUGH COLDER
AIR MOVING IN BEHIND THE DEPARTING LOW WILL LIKELY CHANGE PRECIP
OVER TO SNOW SHOWERS IN THE MOUNTAINS AT SOME POINT WEDNESDAY
MORNING.
SHOULD SEE SOME CLEARING WEDNESDAY AFTERNOON DOWNWIND OF THE
MOUNTAINS AS LOW PRESSURE PULLS AWAY AND A WEAK RIDGE OF HIGH
PRESSURE BUILDS IN FROM THE WEST.
SEVERAL WEAK FRONTS WILL MOVE TOWARD THE REGION FROM THE NORTHWEST
WEDNESDAY NIGHT AND THURSDAY...THE FIRST OF WHICH WILL FIZZLE OUT IN
THE MOUNTAINS BRINGING THICKENING CLOUDS AND A CHANCE OF A FLURRY
THURSDAY MORNING. ANOTHER FRONT WILL SHIFT INTO NORTHWEST ZONES THURSDAY
EVENING BRINGING A BETTER CHANCE OF SNOW SHOWERS. FRONT PUSHES
OFFSHORE EARLY FRIDAY AS A WEAK RIDGE OF HIGH PRESSURE SETTLES
INTO THE NORTHEAST.
&&
.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
SHORT TERM...VFR CONDITIONS EXPECTED TONIGHT EXCEPT FOR A BRIEF
PERIOD OF MVFR CIGS THROUGH 01Z OR SO IN SPOTS. OTHERWISE...VFR
CONDITIONS AND LIGHT WINDS ARE EXPECTED FOR SATURDAY AND SATURDAY
NIGHT.
LONG TERM...VFR SUNDAY THROUGH MONDAY. IFR/LIFR CEILINGS/VSBY
DEVELOPING MONDAY NIGHT...PERSISTING THROUGH TUESDAY NIGHT.
BECOMING VFR ON WEDNESDAY.
&&
.MARINE...
SHORT TERM...SCA CONDITIONS /SEAS 5+ FT/ WILL LIKELY RESUME LATE
THIS EVENING OR OVERNIGHT ON THE OCEAN AND CONTINUE THROUGH
SATURDAY.
LONG TERM...WINDS MAY REACH MINIMAL SCA LEVELS SUNDAY.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 5 PM EST
SATURDAY FOR ANZ150-152-154.
&&
$$
LEGRO
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
406 PM EST THU DEC 1 2011
.SYNOPSIS...
HIGH PRESSURE BUILDS INTO THE MID ATLANTIC REGION FROM THE WEST
TONIGHT THROUGH WEEKEND. A WEAK...DRY COLD FRONT WILL CROSS INTO
THE AREA FRIDAY NIGHT...BRINGING SLIGHTLY COOLER TEMPERATURES
SATURDAY. MILDER CONDITIONS RETURN FOR THE LATTER HALF OF THE
WEEKEND INTO EARLY NEXT WEEK AHEAD OF A SLOW MOVING COLD
FRONT...WHICH APPROACHES THE REGION FROM THE WEST BY THE MIDDLE OF
NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
LATEST WX ANALYSIS DEPICTS ~1028MB SURFACE HIGH PRESSURE OVER
E KY/TN. ALOFT...TROUGH-RIDGE-TROUGH PATTERN EVIDENT ON RUC H5
ANALYSIS AS MID LEVEL TROUGHING HAS NOW TRANSITIONED OFF THE EAST
COAST...WITH LOW AMPLITUDE H5 RIDGING TO THE WEST OVER THE GULF
COAST/LOWER MS VALLEY...WITH CLOSED OFF/POSITIVELY TILTED UPPER
LEVEL LOW PRESSURE REMAINS IN PLACE OVER BAJA/SOUTHERN
CALIFORNIA.
BREEZY CONDITIONS STILL IN PLACE OVER MAINLY COASTAL ZONES THIS
AFTERNOON AS A RESULT OF PRESSURE GRADIENT BETWEEN DEPARTING MID
LEVEL TROUGH...AND HIGH PRESSURE TO THE WEST. COASTAL AREAS
SHOULD CONTINUE TO BE BREEZY (GUSTS TO 15-17 KT) FOR A FEW MORE
HOURS BEFORE DECOUPLING/RELAXING PRESSURE GRADIENT ALLOWS FOR
WINDS TO DROP OFF EARLY THIS EVENING. OTHERWISE...A MOSTLY CLEAR
AND PLEASANT LATE FALL AFTERNOON ACROSS THE CWA...MAXIMA WL AVERAGE
OUT INTO THE MID 50S INLAND...LOW TO MID 50S OVER COASTAL ZONES.
CLEAR SKIES/LIGHT WINDS PORTEND TO GOOD RADIATING CONDITIONS
TONIGHT. LOOKING FOR TEMPERATURES BE CLOSE TO/JUST BELOW LAST
NIGHTS/THIS MORNING`S LOWS. LOOK FOR LOWS INTO THE M-U 20S
INLAND...LOW TO MID 30S OVER COASTAL ZONES.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY/...
LATE WEEK/WEEKEND TIME FRAME CHARACTERIZED BY SLOWLY BUILDING UPPER
LEVEL RIDGING WITH TIME OVER THE EASTERN CONUS...RESULTING IN
CONTINUED DRY WEATHER THROUGH THE PERIOD.
FRIDAY...
HIGH PRESSURE BECOMES ENTRENCHED OVER THE MID ATLANTIC
STATES THROUGH THE WEEKEND. AS A CUTOFF LOW DEVELOPS OVER THE
SOUTHWESTERN US...A WEAK UPPER LEVEL TROUGH WILL BECOME SEPARATED
FROM IT AND DRIFT ACROSS THE NORTHERN PLAINS/UPPER GREAT
LAKES...BEFORE SLOWLY PUSHING ACROSS NEW ENGLAND BY FRIDAY NIGHT.
THIS FEATURE WILL EVENTUALLY PUSH WEAK/DRY FRONTAL BOUNDARY TO OUR
NORTH THROUGH THE REGION LATE TOMORROW INTO SATURDAY WITH LITTLE
MORE THAN A FEW MID-HIGH CLOUDS PUSHING ACROSS THE AREA. MAXIMA
SLIGHTLY WARMER THAN TODAY`S VALUES...GENERALLY INTO THE M/U 50S
AREA WIDE...NEAR 60 WELL INLAND. SO WHILE WE CAN EXPECT A SLIGHTLY
MILDER EVENING FRIDAY NIGHT...HAVE SIDED CLOSER TO COOLER ENVELOPE
OF MAV GUIDANCE IN EXPECTATION OF LIGHT WINDS OVER LAND AND STILL
RELATIVELY SCANT MID LEVEL CLOUD COVER AS HIGH PRESSURE SLIDES
OVERHEAD. EARLY MORNING LOWS FRI NIGHT/SAT MORNING GENERALLY INTO
THE L-M30S TO NEAR 40 ALONG COASTAL ZONES.
SATURDAY...
THE SURFACE HIGH BECOMES POSITIVELY TILTED ON SATURDAY AS THE
RIDGE AXIS BEGINS TO SHIFT OFFSHORE. DESPITE AFOREMENTIONED
WARMING WITH TIME ALOFT AS SUBTROPICAL RIDGE BEGINS TO BUILD ACROSS
THE SOUTHEASTERN CONUS...TEMPERATURES WILL BE MODESTLY COOLER
SATURDAY DUE TO THE INFLUENCE OF MODIFYING ~1036MB SFC HIGH
PRESSURE PUSHING IN FROM THE WEST. AS WE`VE SEEN SEVERAL TIMES
ALREADY THIS FALL...LIMITED MIXING NOTED ON FORECAST SOUNDINGS FOR
SATURDAY (GENERALLY TO ~950-925MB) WILL KEEP TEMPERATURES A BIT
LOWER THAN LOCAL THICKNESS TOOLS AND WARMER MAV GUIDANCE DEPICT.
AS SUCH...HAVE GONE CLOSER TO COOLER MET VALUES FOR MAXIMA ON
SATURDAY WHICH YIELD SEASONABLE...ALBEIT SLIGHTLY COOLER...MAXIMA
INTO THE LOW TO MID 50S.
SATURDAY NIGHT/SUNDAY...
SURFACE HIGH PIVOTS TO THE MID-ATLANTIC/SE COAST AND THEN
OFFSHORE SAT NIGHT THROUGH SUNDAY...WITH DEVELOPING RETURN (SOUTH-
SOUTHEAST) FLOW AND CONTINUED BUILDING OF RIDGING ALOFT INITIATING
MODERATING TEMPERATURE TREND FOR SATURDAY NIGHT THROUGH THE EARLY
PORTION OF NEXT WEEK. LOOK FOR EARLY MORNING LOWS CONTINUED DRY
AND MILDER CONDITIONS SUNDAY WITH MAXIMA INTO THE L-M 60S.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
OVERALL PATTERN IN THE EXTENDED FAVORS A DOMINANT MID/UPPER LEVEL
RIDGE CENTERED FROM THE GULF OF MEXICO ENE ACRS FLORIDA AND TOWARDS
BERMUDA. MEANWHILE...A DEEP TROUGH OVER CENTRAL CANADA WILL
GRADUALLY PUSH SOUTH AND TAKE ON A POSITIVE TILT (OR EVEN BECOME
CUTOFF) OVER THE CENTRAL CONUS. THIS SETUP WILL BE VERY SLOW TO
CHANGE THROUGH THE MIDDLE OF NEXT WEEK...AND WILL KEEP BULK OF
PRECIPITATION OFF TO OUR WEST UNTIL WED. FOR THE MID ATLC AND SE
STATES...THIS WILL ALSO TRANSLATE INTO WELL ABOVE AVG TEMPERATURES
MON-TUE...AND POSSIBLY WED BEFORE COOLING DOWN TO AROUND AVG ON THU.
GIVEN THE CONTINUED MODEL DISCREPANCIES (LATEST ECMWF REMAINING
ABOUT 12-18 HRS SLOWER THAN THE GFS/GLOBAL GEM
ENSEMBLES....CONFIDENCE IN TUE-THU FCST IS LOWER THAN AVG.
AS WITH PREVIOUS FCST...HAVE GENLY BROAD-BRUSHED A LOW CHANCE POP
ACRS THE NW ZONES...TO DRY OR SLIGHT CHANCE ELSEWHERE FROM LATE MON
THROUGH TUE. WILL FOCUS HIGHEST POPS DURING THE DAY WED/WED EVENING
AS A BLEND OF MODEL TIMING PUSHES THE SFC COLD FRONT THROUGH.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
HIGH PRES CENTERED OVER THE OH VALLEY WILL KEEP SKIES CLEAR
THROUGH THE TAF PERIOD AND INTO LATE FRI. A MOSTLY DRY COLD FRONT
WILL APPROACH LATE FRI INTO SAT. VFR CONDITIONS ARE EXPECTED
THROUGH THE WEEKEND.
&&
.MARINE...
SCA HEADLINES ARE IN THE PROCESS OF BEING TRIMMED BACK W/ AFTN
PACKAGE...GENLY KEEPING SCA HEADLINES IN EFFECT OVER SOUTHERN AREAS
INTO THE EVENING...WHILE WINDS ARE A BIT LIGHTER TO THE NORTH WHERE
THE HEADLINES ARE ENDING. FOR SOUTHERN COASTAL WATERS THE SCA
HEADLINES MAY NEED TO BE EXTENDED BEYOND THE EVENING IF SEAS ARE
SLOWER TO DROP THAN FCST.
QUIET CONDITIONS FRI...FOLLOWED BY ANOTHER BOUNDARY/COOL SURGE FRI
NIGHT...WITH MARGINAL SCA EVENT LIKELY ONCE AGAIN OVER THE
BAY....AND POSSIBLE ON THE COASTAL WATERS. AS THIS IS LATER 3RD
PERIOD...HAVE DECIDED TO WAIT UNTIL CURRENT HEADLINES END BEFORE
RAISING ANOTHER SET (ALTHOUGH FCST DOES INCLUDE SCA CONDITIONS).
THIS SURGE IS FAIRLY BRIEF...AND SHOULD END BY LATE SAT MORNING
ASIDE FROM LINGERING 5 FT SEAS OVER SOUTHERN COASTAL WATERS.
OTHERWISE...BENIGN SAT EVENING THROUGH MON AS HIGH PRESSURE SETTLES
OVER THE REGION AHEAD OF THE NEXT COLD FRONT. WINDS GRADUALLY TURN
SOUTHERLY SUN-TUE BUT WIND SPEEDS LOOK TO AVG 10-15 KT OR LESS.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR
ANZ633. SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR
ANZ656- 658.
&&
$$
SYNOPSIS...MAM
NEAR TERM...MAM
SHORT TERM...MAM/BMD
LONG TERM...LKB
AVIATION...JEF
MARINE...LKB
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
759 AM EST THU DEC 1 2011
.SYNOPSIS...
EXCEPT FOR A PASSING SHOWER NORTH OF INTERSTATE 80 FRIDAY
AFTERNOON...EXPECT DRY AND SEASONABLE WEATHER UNTIL A COLD FRONT
APPROACHES THE REGION SUNDAY NIGHT.
&&
.NEAR TERM /THROUGH TONIGHT/...
A QUICK MORNING UPDATE HAS BEEN ISSUED THIS MORNING TO ACCOUNT FOR
THE LATEST TRENDS WITH PATCHES OF STRATOCUMULUS LINGERING ACROSS
EASTERN OHIO AND THE EASTERN RIDGES.
LOWER CLOUDS SHOULD QUICKLY DIMINISH AFTER SUNRISE AS DAYTIME
HEATING MIXES DRIER AIR TO THE SURFACE. WITH HIGH PRESSURE IN
CONTROL...EXPECT LIGHT WINDS AND MOSTLY SUNNY SKIES TODAY. SOME
CLOUD COVER WILL MOVE IN LATE TONIGHT AS A WEAK FRONT APPROACHES
FROM THE WEST.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY/...
A WEAK FRONT WILL MOVE ACROSS THE REGION FRIDAY. STILL APPEARS THAT
THE PRIMARY IMPACTS WILL BE INCREASED CLOUD COVER AND A WIND SHIFT.
MODELS INDICATE THAT AN ISOLATED SHOWER COULD OCCUR NORTH OF
INTERSTATE 80...BUT MODELS HAVE BEEN CONSISTENT OVER THE LAST FEW
DAYS SHOWING NO THREAT OF PRECIP SOUTH OF THE INTERSTATE.
THE INFLUENCE OF HIGH PRESSURE WILL RETURN FRIDAY NIGHT...
CLEARING SKIES OUT. SOUTHERLY WINDS ON SATURDAY WILL PROMOTE A
SLIGHT WARMUP AND BRING HIGHS A FEW DEGREES ABOVE NORMAL.
CLOUDS WILL INCREASE ONCE AGAIN SATURDAY NIGHT AS A MORE POTENT
FRONT MOVES ACROSS THE PLAINS. WILL INCREASE POPS TO HIGH CHANCE
ACROSS OHIO BY SUNDAY AFTERNOON.
&&
.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
NEXT SYSTEM PROGGED TO APPROACH THE REGION LATE SUNDAY. CURRENTLY
MODELS INDICATE A SERIES OF SHORTWAVES DEEPENING THE POSITIVELY
TILTED UPPER LEVEL TROUGH AND ALLOWING FOR VERY COLD H850
TEMPERATURES OVER CANADA TO SINK SOUTHWARD TO AS FAR AS
MISSISSIPPI VALLEY BY TUESDAY.
HAVE BUMPED POPS UP TO LIKELY FOR SUNDAY NIGHT INTO MONDAY WITH
GOOD CONSENSUS BETWEEN 01/00Z GFS/ECMWF/NAEFS...AND WILL CONTINUE
CHANCE POPS FOR MONDAY NIGHT INTO TUESDAY.
WITH THE H850 TEMPERATURES REACHING -12C AND NORTHWEST
FLOW...HIGH TEMPERATURES COULD BE 10 DEGREES BELOW NORMAL TUESDAY
AND WEDNESDAY.
&&
.AVIATION /13Z THURSDAY THROUGH MONDAY/...
RECENT SURFACE AND IR SATELLITE DATA CONTINUE TO SHOW PATCHES OF
MVFR STRATUS ACROSS EASTERN OHIO, SOUTHWESTERN PENNSYLVANIA, AND
ACROSS THE APPALACHIAN MOUNTAINS. THE STRATUS FORMED OVERNIGHT DUE
TO NOCTURNAL COOLING OF MOISTURE TRAPPED BENEATH A STRENGTHENING
SUBSIDENCE INVERSION. THE CLOUDS HAVE BEEN MOVING TOWARD THE
NORTHEAST. HOWEVER, EXPECT ALL THE STRATUS TO DISSIPATE BY 15Z
AS SUPPORTED BY RECENT HRRR MODEL OUTPUT. EXPECT VFR CLEAR TO
CONTINUE THROUGH TONIGHT.
OUTLOOK...FRIDAY THROUGH MONDAY...
PREVALENT VFR THROUGH SATURDAY, EXCEPT NEAR I-80 LATE FRIDAY DUE TO
POSSIBLE RESTRICTIONS WITH SCATTERED COLD FRONTAL SHOWERS. MORE
WIDESPREAD RESTRICTIONS STARTING LATE SUNDAY WITH INCOMING MIDWEST
COLD FRONTAL BAND OF SHOWERS.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
651 AM EST THU DEC 1 2011
.SYNOPSIS...
EXCEPT FOR A PASSING SHOWER NORTH OF INTERSTATE 80 FRIDAY
AFTERNOON...EXPECT DRY AND SEASONABLE WEATHER UNTIL A COLD FRONT
APPROACHES THE REGION SUNDAY NIGHT.
&&
.NEAR TERM /THROUGH TONIGHT/...
LOWER CLOUDS SHOULD QUICKLY DIMINISH AFTER SUNRISE AS DAYTIME
HEATING MIXES DRIER AIR TO THE SURFACE. WITH HIGH PRESSURE IN
CONTROL...EXPECT LIGHT WINDS AND MOSTLY SUNNY SKIES TODAY. SOME
CLOUD COVER WILL MOVE IN LATE TONIGHT AS A WEAK FRONT APPROACHES
FROM THE WEST.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY/...
A WEAK FRONT WILL MOVE ACROSS THE REGION FRIDAY. STILL APPEARS THAT
THE PRIMARY IMPACTS WILL BE INCREASED CLOUD COVER AND A WIND SHIFT.
MODELS INDICATE THAT AN ISOLATED SHOWER COULD OCCUR NORTH OF
INTERSTATE 80...BUT MODELS HAVE BEEN CONSISTENT OVER THE LAST FEW
DAYS SHOWING NO THREAT OF PRECIP SOUTH OF THE INTERSTATE.
THE INFLUENCE OF HIGH PRESSURE WILL RETURN FRIDAY NIGHT...
CLEARING SKIES OUT. SOUTHERLY WINDS ON SATURDAY WILL PROMOTE A
SLIGHT WARMUP AND BRING HIGHS A FEW DEGREES ABOVE NORMAL.
CLOUDS WILL INCREASE ONCE AGAIN SATURDAY NIGHT AS A MORE POTENT
FRONT MOVES ACROSS THE PLAINS. WILL INCREASE POPS TO HIGH CHANCE
ACROSS OHIO BY SUNDAY AFTERNOON.
&&
.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
NEXT SYSTEM PROGGED TO APPROACH THE REGION LATE SUNDAY. CURRENTLY
MODELS INDICATE A SERIES OF SHORTWAVES DEEPENING THE POSITIVELY
TILTED UPPER LEVEL TROUGH AND ALLOWING FOR VERY COLD H850
TEMPERATURES OVER CANADA TO SINK SOUTHWARD TO AS FAR AS
MISSISSIPPI VALLEY BY TUESDAY.
HAVE BUMPED POPS UP TO LIKELY FOR SUNDAY NIGHT INTO MONDAY WITH
GOOD CONSENSUS BETWEEN 01/00Z GFS/ECMWF/NAEFS...AND WILL CONTINUE
CHANCE POPS FOR MONDAY NIGHT INTO TUESDAY.
WITH THE H850 TEMPERATURES REACHING -12C AND NORTHWEST
FLOW...HIGH TEMPERATURES COULD BE 10 DEGREES BELOW NORMAL TUESDAY
AND WEDNESDAY.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
RECENT SURFACE AND IR SATELLITE DATA CONTINUE TO SHOW PATCHES OF
MVFR STRATUS ACROSS EASTERN OHIO, SOUTHWESTERN PENNSYLVANIA, AND
ACROSS THE APPALACHIAN MOUNTAINS. THE STRATUS FORMED OVERNIGHT DUE
TO NOCTURNAL COOLING OF MOISTURE TRAPPED BENEATH A STRENGTHENING
SUBSIDENCE INVERSION. THE CLOUDS HAVE BEEN MOVING TOWARD THE
NORTHEAST. HOWEVER, EXPECT ALL THE STRATUS TO DISSIPATE BY 15Z
AS SUPPORTED BY RECENT HRRR MODEL OUTPUT. EXPECT VFR CLEAR TO
CONTINUE THROUGH TONIGHT.
OUTLOOK...FRIDAY THROUGH MONDAY...
PREVALENT VFR THROUGH SATURDAY, EXCEPT NEAR I-80 LATE FRIDAY DUE TO
POSSIBLE RESTRICTIONS WITH SCATTERED COLD FRONTAL SHOWERS. MORE
WIDESPREAD RESTRICTIONS STARTING LATE SUNDAY WITH INCOMING MIDWEST
COLD FRONTAL BAND OF SHOWERS.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
326 AM EST THU DEC 1 2011
.SYNOPSIS...
EXCEPT FOR A PASSING SHOWER NORTH OF INTERSTATE 80 FRIDAY
AFTERNOON...EXPECT DRY AND SEASONABLE WEATHER UNTIL A COLD FRONT
APPROACHES THE REGION SUNDAY NIGHT.
&&
.NEAR TERM /THROUGH TONIGHT/...
LOWER CLOUDS HAVE STUBBORNLY PERSISTED ALONG THE PA/WV/MD RIDGES AND
ACROSS PORTIONS OF CENTRAL OH. THESE CLOUDS SHOULD QUICKLY DIMINISH
AFTER SUNRISE AS DAYTIME HEATING MIXES DRIER AIR TO THE SURFACE.
WITH HIGH PRESSURE IN CONTROL...EXPECT LIGHT WINDS AND MOSTLY SUNNY
SKIES TODAY. SOME CLOUD COVER WILL MOVE IN LATE TONIGHT AS A WEAK
FRONT APPROACHES FROM THE WEST.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY/...
A WEAK FRONT WILL MOVE ACROSS THE REGION FRIDAY. STILL APPEARS THAT
THE PRIMARY IMPACTS WILL BE INCREASED CLOUD COVER AND A WIND SHIFT.
MODELS INDICATE THAT AN ISOLATED SHOWER COULD OCCUR NORTH OF
INTERSTATE 80...BUT MODELS HAVE BEEN CONSISTENT OVER THE LAST FEW
DAYS SHOWING NO THREAT OF PRECIP SOUTH OF THE INTERSTATE. THE
INFLUENCE OF HIGH PRESSURE WILL RETURN FRIDAY NIGHT...CLEARING SKIES
OUT. SOUTHERLY WINDS ON SATURDAY WILL ALLOW FOR A SLIGHT
WARMUP...BRING HIGHS A FEW DEGREES ABOVE NORMAL. CLOUDS WILL
INCREASE ONCE AGAIN SATURDAY NIGHT AS A MORE POTENT FRONT MOVES
ACROSS THE PLAINS. WILL INCREASE POPS TO HIGH CHANCE ACROSS OHIO BY
SUNDAY AFTERNOON.
&&
.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
NEXT SYSTEM PROGGED TO APPROACH THE REGION LATE SUNDAY. CURRENTLY
MODELS INDICATE A SERIES OF SHORTWAVES DEEPENING THE POSITIVELY
TILTED UPPER LEVEL TROUGH AND ALLOWING FOR VERY COLD H850
TEMPERATURES OVER CANADA TO SINK SOUTHWARD TO AS FAR AS
MISSISSIPPI VALLEY BY TUESDAY. HAVE BUMPED POPS UP TO LIKELY FOR
SUNDAY NIGHT INTO MONDAY WITH GOOD CONSENSUS BETWEEN 01/00Z
GFS/ECMWF/NAEFS...AND WILL CONTINUE CHANCE POPS FOR MONDAY NIGHT
INTO TUESDAY. WITH THE H850 TEMPERATURES REACHING -12C AND
NORTHWEST FLOW...HIGH TEMPERATURES COULD BE 10 DEGREES BELOW
NORMAL TUESDAY AND WEDNESDAY.
&&
.AVIATION /08Z THURSDAY THROUGH MONDAY/...
PER RECENT SURFACE AND IR SATELLITE DATA, THE TWO DISTINCT BANDS OF
MVFR STRATUS ACROSS THE UPPER OHIO VALLEY, HAVE EXPANDED IN COVERAGE
SINCE MIDNIGHT. THE FIRST BAND WAS NEAR THE MOUNTAINS AND LIKELY
CAUSED BY A CHANNELING OF UPSLOPE FLOW. THE SECOND BAND, POSSIBLY
CAUSED BY NOCTURNAL COOLING OF TRAPPED MOISTURE BENEATH A
STRENGTHENING LOWLEVEL SUBSIDENCE INVERSION, EXTENDED FROM KMFD
SOUTHEASTWARD TO KMGW. MOST OF THE RECENT EXPANSION HAS OCCURRED
OVER OHIO AND NEAR THE INTERSECTIONS OF THE TWO BANDS OVER NORTHERN
WEST VIRGINIA.
PER RECENT HRRR MODEL OUTPUT, EXPECT MVFR STRATUS TO PERSIST INTO
14Z, WHERE IT HAS BEEN OCCURRING. NEARBY TAF SITES, LIKE KHLG AND
KZZV, MAY EXPERIENCE AN INCREASE IN STRATUS BEFORE THEN ALSO. OTHER
SITES LIKE KZZV OR KDUJ MAY SEE MVFR FOG DEVELOPMENT ALSO.
SOME FOG CAN ALSO DEVELOP IN THE RIVER VALLEYS, AS THE AIR
TEMPERATURES ARE ALMOST 20 DEGREES COLDER THAN NEARBY WATER
TEMPERATURES IN THE MID 40S. SURFACE WINDS OVER 3 KTS MAY PRECLUDE
THE FOG FROM EXPANDING TO AFFECT NEARBY TAF SITES.
BY 15Z, EXPECT VFR CLEAR FOR ALL SITES, TO BE MAINTAINED THROUGH
TONIGHT.
OUTLOOK...FRIDAY THROUGH MONDAY...
PREVALENT VFR THROUGH SATURDAY, EXCEPT NEAR I-80 LATE FRIDAY DUE TO
POSSIBLE RESTRICTIONS WITH SCATTERED COLD FRONTAL SHOWERS. MORE
WIDESPREAD RESTRICTIONS STARTING LATE SUNDAY WITH INCOMING MIDWEST
COLD FRONTAL BAND OF SHOWERS.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
104 AM EST THU DEC 1 2011
.SYNOPSIS...
AS LOW PRESSURE EXITS TO THE NORTHEAST... SKIES WILL GENERALLY
CLEAR OVERNIGHT. HIGH PRESSURE WILL KEEP THE REGION COOL AND DRY
INTO THE WEEKEND.
&&
.NEAR TERM /THROUGH TODAY/...
06Z UPDATE PRIMARILY FOR CLOUD COVER. A RING OF LOW CLOUDS HAS
DEVELOPED FROM BRADFORD SOUTH TO OAKLAND...AND BACK WEST TO
ZANESVILLE. SOME MOISTURE FROM YESTERDAYS RAINFALL MAY STILL BE
TRAPPED IN LOWEST LEVELS IN THESE LOCATIONS. CURRENT FORECAST HAS
THESE CLOUDS SLOWLY DISSIPATE...BUT CANNOT RULE OUT THE
POSSIBILITY THAT THE CLOUDS WILL PERSIST UNTIL AFTER SUNRISE AND
LOW LEVELS MIX OUT. THURSDAY WILL BE QUIET AS THE HIGH PRESSURE
STRENGTHENS OVER MUCH OF THE EASTERN U.S. KEPT TEMPERATURES CLOSE
TO NORMAL.
&&
.SHORT TERM /TONIGHT THROUGH SATURDAY/...
HIGH PRESSURE WILL MAINTAIN IT`S POSITION KEEPING MOST OF THE AREA
DRY THROUGHOUT THE PERIOD. A WEAK FRONT WILL DROP ACROSS THE
REGION LATE FRIDAY BUT AS MODELS HAVE INDICATED OVER THE LAST
COUPLE OF DAYS...THERE IS LIMITED MOISTURE TO SUPPORT MUCH IN THE
WAY OF PRECIPITATION. KEPT THE PREVIOUS FORECAST OF SLIGHT CHANCE
POPS NORTH OF THE I-80 AND LEFT IT DRY ELSEWHERE. LITTLE CHANGE
EXPECTED IN WEATHER FOR SATURDAY. TEMPERATURES SHOULD REMAIN NEAR
NORMAL FOR THIS TIME OF YEAR...GRADUALLY INCREASING TO ABOVE
NORMAL ON SATURDAY AS THE HIGH SLIDES OFF THE EAST COAST.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
NEXT SYSTEM PROGGED TO APPROACH THE REGION LATE SUNDAY. CURRENTLY
MODELS INDICATE A SERIES OF SHORTWAVES DEEPENING THE POSITIVELY
TILTED UPPER LEVEL TROUGH AND ALLOWING FOR VERY COLD H850
TEMPERATURES OVER CANADA TO SINK SOUTHWARD TO AS FAR AS
MISSISSIPPI VALLEY BY TUESDAY. THIS COULD ALLOW FOR WIDESPREAD
SNOW SHOWERS OVERNIGHT MONDAY INTO TUESDAY BUT GENERALLY KEPT POPS
IN THE CHANCE CATEGORY THROUGH THE PERIOD AT THIS TIME DUE TO
UNCERTAINTY. WITH THE H850 TEMPERATURES REACHING -12C AND
NORTHWEST FLOW...HIGH TEMPERATURES COULD BE 10 DEGREES BELOW
NORMAL TUESDAY AND WEDNESDAY.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
PER RECENT SURFACE AND IR SATELLITE DATA, TWO NARROW BANDS OF MVFR
STRATUS LIE ACROSS THE UPPER OHIO VALLEY. THE BAND NEAR THE
MOUNTAINS IS LIKELY BEING CAUSED BY UPSLOPE FLOW. NOT SO SURE ABOUT
WHAT IS CAUSING THE SECOND BAND THAT EXTENDS FROM KMFD TO KMGW. PER
RECENT NAM AND RUC MODEL PROFILES, THE BAND COULD BE RELATED TO
TRAPPED MOISTURE BENEATH A GROWING LOWLEVEL SUBSIDENCE INVERSION, AS
INDICATED BY A STRONG H8 TEMPERATURE GRADIENT ABOVE THE STRATUS.
SO USING A BLEND OF PERSISTENCE AND DIURNAL CLIMATOLOGY, HAVE
MAINTAINED MVFR STRATUS WHERE IT NOW OCCURRING, AND HAVE SPREAD
BROKEN MVFR STRATUS TO SOME NEARBY TAF SITES SUCH AS KHLG AND KFKL.
BY 14Z, EXPECT VFR CLEAR FOR ALL SITES, TO BE MAINTAINED THROUGH
TONIGHT.
OUTLOOK...FRIDAY THROUGH MONDAY...
PREVALENT VFR THROUGH SATURDAY, EXCEPT NEAR I-80 LATE FRIDAY DUE TO
POSSIBLE RESTRICTIONS WITH SCATTERED COLD FRONTAL SHOWERS. MORE
WIDESPREAD RESTRICTIONS STARTING LATE SUNDAY WITH INCOMING MIDWEST
COLD FRONTAL BAND OF SHOWERS.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GAYLORD MI
347 PM EST THU DEC 1 2011
.SYNOPSIS.../ISSUED AT 346 PM/
THE LESS THAN IMPRESSIVE COLD FRONT THAT BROUGHT THE CLOUDS AND
PRECIPITATION TODAY...WILL SLIDE SOUTHEASTERLY TONIGHT. THIS WILL
OPEN A SHORT WINDOW OF OPPORTUNITY TONIGHT FOR SOME LAKE EFFECT
FLURRIES INTO THE EARLY MORNING HOURS OF FRIDAY...BUT ANY LINGERING
PRECIPITATION WILL BE GONE BY MID DAY. THAT WILL LEAVE SETTLED
CONDITIONS IN PLACE FOR THE BALANCE OF FRIDAY. HOWEVER...THE QUIET
WEATHER WILL BE SHORT LIVED AS THE NEXT DISTURBANCE MOVES IN ON
SATURDAY AND WILL KEEP RAIN AND SNOW PROBABLE THROUGH THE WEEKEND.
BERGER
&&
.SHORT TERM.../ISSUED AT 346 PM/...TONIGHT
MAIN FCST CHALLENGE HEADING INTO THE NIGHT REVOLVES AROUND LINGERING
LIGHT PRECIP CHANCES ACROSS SOUTHERN COUNTIES...AND POTENTIAL FOR
SOME WEAK LAKE EFFECT OVERNIGHT. EARLY AFTN ANALYSIS PLACES A COLD
FRONT AT THE SURFACE DRAPED ACRS NORTHWEST LOWER...TIED TO WEAK
SURFACE LOW CROSSING MANITOULIN ISLAND AS OF 19Z. REGIONAL RADAR
MOSAIC CONTINUES TO SHOW AN ELONGATED AXIS OF MAINLY LIGHT PRECIP
BISECTING MAINLY NORTHERN LOWER...DRIVEN BY COMBO OF FAIRLY DEEP
FRONTOGENETICAL FORCING AND UPPER JET DIVERGENCE IMMEDIATELY IN THE
WAKE OF THE SURFACE BOUNDARY. PRECIP TYPE THUS FAR THIS AFTN HAS
BEEN MAINLY LIQUID OUTSIDE OF THE HIGHER TERRAIN...THANKS TO
GENEROUSLY WARM BOUNDARY LAYER...WITH SFC-BASED MELTING LAYERS
PUSHING 1.5KFT PER LATEST RUC FCST RAOBS. LATEST RADAR IMAGES HAVE
SHOWN SOME INTENSIFICATION OF THE PRECIP RETURNS...LIKELY THE
CONSEQUENCE OF STRENGTHENING FGEN AS COLD ADVECTION INCREASES...AND
SOME UPTICK IN MID LEVEL QG UPWARD FORCING WITH APPROACH OF
SHARPENING UPPER TROUGH FROM THE UPPER MIDWEST.
FORESEE THIS BAND OF FGEN-DRIVEN PRECIP GRADUALLY PROGRESSING
SOUTHWARD INTO THE AFTN AND EVENING HOURS...AND WILL RATHER RAPIDLY
FLIP THE PRECIP TYPE OVER TO ALL SNOW AS THE SUN SETS AND SHALLOW
MELTING LAYER IS ERASED VIA QUICK PUSH OF STRONGER COLD ADVECTION.
THEREAFTER...FOCUS IS ON WHETHER LAKE EFFECT PRECIP WILL DEVELOP OR
NOT. INCOMING AIR MASS IS CERTAINLY COLD ENOUGH (900MB TEMPS RUNNING
AROUND -10C TO -13C)...BUT IS VERY DRY...WITH UPSTREAM PWATS BELOW
0.1 INCHES! (SEE SFC DEW POINTS INTO THE SINGLE DIGITS). AS
SUCH...BELIEVE THAT WE WILL LIKELY SEE SOME LIMITED LAKE
RESPONSE...BUT HAVE A HARD TIME SEEING MUCH MORE THAN JUST SOME
FLURRIES FALLING ACROSS NORTHERN LOWER...WHILE DEEPER PUSH OF COLD
ADVECTION MAY ALLOW FOR SOME SCATTERED SNOW SHOWERS INTO THE EASTERN
U.P. IN FACT...ALREADY SEEING SOME STREAMERS UP THAT WAY...SO WILL
ADD IN A SMALL POP FOR MEASURABLE SNOW. OVERNIGHT LOWS CHILLY...DOWN
INTO THE UPPER TEENS TO MIDDLE 20S.
LAWRENCE
&&
.LONG TERM.../ISSUED AT 346 PM/...FRIDAY AND BEYOND
SHORT RANGE (FRIDAY)...LOOKING LIKE A RATHER NICE EARLY DECEMBER DAY
ON TAP WITH BONE DRY AIR MASS FILTERING INTO THE REGION AS LOW
LEVEL RIDGING TRAVERSES THE SOUTHERN LAKES. COULD PERHAPS SEE SOME
LINGERING LAKE CLOUDS FOR A BRIEF TIME INTO THE MORNING...BUT
THOSE SHOULDN`T LAST WITH BACKING SOUTHWEST FLOW AND QUICK PUSH OF
WARM ADVECTION REALLY LIMITING LAKE INSTABILITY AFTER 15Z. IT WILL
STILL BE SEASONABLY CHILLY DESPITE THE EXPECTATION OF NEARLY FULL
SUNSHINE...WITH HIGHS ONLY INTO THE LOWER OR MIDDLE 30S.
LAWRENCE
OUTLOOK RANGE (FRIDAY NIGHT THROUGH THURSDAY)...LONG WAVE TROUGH
EXTENDS FROM BAFFIN ISLAND SOUTH INTO THE NATION`S HEARTLAND...WITH
BUILDING HEIGHTS OVER THE EASTERN PACIFIC. TROUGHING BECOMES MORE
AMPLIFIED OVER THE NEXT SEVERAL DAYS AS A SHORT WAVE COMING OVER THE
TOP OF THE PACIFIC RIDGE THIS AFTERNOON SPLITS INTO TWO PIECES...
WITH ONE PIECE DROPPING INTO THE SOUTHWESTERN STATES (AND KICKING
UPPER LOW CURRENTLY THERE TO THE NORTHEAST THIS WEEKEND...WHICH WILL
HAVE AN IMPACT ON GREAT LAKES WEATHER). THIS WILL ALSO SERVE TO
STRENGTHEN RIDGING OVER THE SOUTHEASTERN U.S. AND BRING HIGHER
HEIGHTS AND SOUTHWEST FLOW ALOFT INTO MICHIGAN TO END THE WEEK.
QUIETEST FORECAST PERIOD THROUGH SUNDAY WILL BE FRIDAY NIGHT AS
SHORT WAVE RIDGE AXIS CROSSES THE UPPER LAKES...CLOUDS WILL BE ON
THE INCREASE OVERNIGHT INTO SATURDAY MORNING WITHIN ISENTROPIC
ASCENT PATTERN...WITH MOIST LAYER DEEPENING DURING THE DAY AND
ALLOWING FOR WIDESPREAD MOSTLY LIGHT PRECIPITATION TO DEVELOP.
PRECIPITATION TYPE WILL MOSTLY LIKELY START OUT AS SNOW OR A MIX
(CLOSER TO LAKES MICHIGAN/HURON) ACROSS EASTERN UPPER...AND A MIX
ACROSS THE TIP OF THE MITT AND HIGHER ELEVATIONS ACROSS THE INTERIOR
(MAYBE A BRIEF EARLY FREEZING RAIN THREAT). PRECIPITATION SHOULD
TREND TOWARD ALL LIQUID DURING THE DAY WITHIN WARM ADVECTION
PATTERN.
GUIDANCE HAS BEEN PRETTY CONSISTENT WITH A SIGNAL TOWARD DRYING
THINGS OUT IN THE LOW LAYERS SATURDAY EVENING AT LEAST ACROSS
NORTHERN LOWER...WHICH WOULD CUT PRECIP OVER TO JUST SOME DRIZZLE
FOR A TIME DURING THE EVENING BEFORE DEEP (AND BETTER FROM AN
ABSOLUTE STANDPOINT) MOISTURE SURGES BACK IN OVERNIGHT AS A WEAK
SURFACE WAVE LIFTS NORTHEAST INTO ILLINOIS/WISCONSIN AND LOW LEVEL
JET FOCUSES TOWARD THE UPPER LAKES. PRECIPITATION MAY TEND TO BE
MORE PERSISTENT ACROSS THE UPPER PENINSULA SATURDAY NIGHT...AND
APPROACH OF SURFACE LOW AND FRONTAL BOUNDARY THAT EXTENDS TO ITS
NORTHEAST ALSO MEANS THAT COLDER AIR COULD BE FLIRTING WITH EASTERN
UPPER MICHIGAN OVERNIGHT. WHETHER EASTERN UPPER GOES BACK OVER TO
ALL SNOW WILL BE VERY SENSITIVE TO SURFACE LOW POSITION/TRACK...SO
NO NEED TO GET OVERLY CUTE HERE AND WILL KEEP FORECAST WORDING MORE
"MIXY" NORTH OF THE BRIDGE. THIS SAME DILEMMA CONTINUES INTO SUNDAY
AND WHETHER WE STAY ON THE WARM OR COLD SIDE OF THE SURFACE LOW
TRACK AS IT LIFTS NORTHEAST INTO LOWER MICHIGAN. IN ADDITION...
LOOKS LIKE SOME DRY SLOTTING MAY GET INVOLVED IN TERMS OF RATCHETING
DOWN PRECIP INTENSITY BY AFTERNOON. SO AGAIN...PRETTY GENERIC
FORECAST WORDING WILL HAVE TO SUFFICE.
STARTING OUT THE EXTENDED PERIODS MONDAY...SPLIT FLOW POSITIVE TILT
LONG WAVE TROUGH WILL EXTEND FROM HUDSON BAY INTO THE SOUTHWEST
U.S....WITH SOME DIFFERENCES IN THE GUIDANCE WITH RESPECT TO THE
"DEGREE" OF THIS SPLIT AND OVERALL TROUGH EVOLUTION. OPERATIONAL
GFS HAS BEEN RETICENT TO LEAVE ENERGY BEHIND OVER THE SOUTHWESTERN
U.S....WHILE THE GGEM HAS MORE "BEEF" TO ITS NORTHERN BRANCH FLOW.
WHILE THE LATTER IS A BIT OF AN OUTLIER...DON`T WANT TO TOTALLY
DISCOUNT THE GGEM AS IT MAY BE ONTO THE RIGHT OVERALL THEME. AT THE
VERY LEAST IT WILL BE TURNING COLDER FOR THE FIRST PART OF THE WEEK
AS UPPER TROUGH AXIS SWINGS THROUGH IN THE MONDAY/TUESDAY TIME FRAME
AND DRAGS A LOBE OF COLD AIR INTO THE UPPER LAKES. THE MAIN IMPACT
IF THE GGEM IDEA IS CORRECT IS A COLDER SOLUTION AND A BETTER THREAT
FOR LAKE ENHANCED SNOW LATER MONDAY AND LAKE EFFECT SNOW EVENT FOR
THE SNOWBELTS TUESDAY. WILL MAKE SOME ATTEMPT TO TREND THE FORECAST
IN THAT DIRECTION...AT LEAST WITHIN THE CONFINES OF WHAT CAN BE DONE
WITHIN THE EXTENDED FORECAST PROCESS. BEYOND THAT HOWEVER...
UNCERTAINTIES MAKE GRAPPLING WITH FORECAST DETAILS IN THE MIDWEEK
PERIOD A VERY LOW CONFIDENCE AFFAIR...INITIAL THOUGHTS ARE THAT COLD
SHOT WILL BE TRANSIENT WITH A MODERATING AIR MASS INTO WEDNESDAY/
THURSDAY. IF THIS IS THE CASE WOULD PROBABLY ALSO HAVE TO DEAL WITH
WARM ADVECTION PRECIPITATION AT SOME POINT.
JPB
&&
.MARINE.../ISSUED AT 346 PM/
SHORT RANGE (TONIGHT/FRIDAY)...BRIEF TIGHTENING OF THE PRESSURE
GRADIENT IN THE WAKE OF A DEPARTING COLD FRONT OVERNIGHT WILL
BRIEFLY KICK UP THE WINDS ON ALL NEARSHORE WATERS...WITH A FEW GUSTS
TO NEAR SMALL CRAFT ADVISORY LEVEL POSSIBLE. WINDS WILL LOWER AND
GRADUALLY BACK TO THE SOUTHWEST INTO FRIDAY...BUT REMAIN 15 KNOTS OR
LESS.
LAWRENCE
OUTLOOK (FRIDAY NIGHT AND BEYOND)...AS SURFACE HIGH PRESSURE PULLS
AWAY TO THE EAST...SOUTHERLY GRADIENT PICKS UP FRIDAY NIGHT AND
CONTINUES INTO SATURDAY. SMALL CRAFT ADVISORIES WILL LIKELY BE
REQUIRED...WITH SOME LOW END GALE FORCE GUSTS POSSIBLE IN LAKE
MICHIGAN NEARSHORE ZONES. WINDS WILL SLACKEN SATURDAY NIGHT/EARLY
SUNDAY AS LOW PRESSURE LIFTS ACROSS LOWER MICHIGAN...WITH WINDS
SWITCHING AROUND TO NORTH/NORTHWEST IN ITS WAKE LATER SUNDAY.
JPB
&&
.AVIATION.../ISSUED AT 1235 PM/...VALID FOR 18Z TAFS
A COLD FRONT WILL CONTINUE CROSSING THE TERMINAL SITES INTO THE
EVENING...BRINGING PERIODS OF MAINLY LIGHT RAIN AND
SPRINKLES...BUT PERHAPS A BRIEF PERIOD OF SOME LIGHT SNOW EARLY
THIS EVENING. MUCH COLDER AIR FILTERING INTO THE AREA LATER
TONIGHT WILL LIKELY BRING AT LEAST SOME SCATTERED LAKE EFFECT
CLOUDS...BUT VERY DRY AIR DOWN LOW SHOULD PREVENT ANYTHING IN THE
WAY OF SNOW SHOWER ACTIVITY. SKIES ARE EXPECTED TO CLEAR
COMPLETELY HEADING INTO FRIDAY MORNING WITH HIGH PRESSURE IN
CONTROL.
LAWRENCE
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1238 PM EST THU DEC 1 2011
UPDATED AVIATION DISCUSSION FOR 18Z TAFS
.SYNOPSIS...
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW WNW FLOW OVER THE
UPR GRT LKS BTWN TROFFING CENTERED OVER HUDSON BAY AND UPR RDG IN
THE SRN PLAINS. POSITIVELY TILTED SHRTWV IN THE NRN PLAINS MOVING
THRU THIS FLOW AND ASSOCIATED SFC LO PRES/COLD FNT STRETCHING FM
NCNTRL WI SWWD INTO THE CENTRAL PLAINS AT 04Z IS BRINGING AN AREA OF
SN TO THE UPR GRT LKS. MAIN FORCING MECHANISMS APPEAR TO BE UPR DVGC
IN EXIT REGION OF SUPPORTING 100KT H3 JET MAX AND BAND OF H85-7 FGEN
ASSOCIATED WITH FRONTAL ZN...BUT DRYNESS OF LLVLS PER NEARBY 00Z
RAOBS/LACK OF SGNFT ISENTROPIC ASCENT/MODEST DEEP LYR QVECTOR CNVGC
IS GENERALLY LIMITING THE OVERALL SN INTENSITY. TO THE NW...
SPRAWLING SFC HI PRES CENTERED JUST W OF LK WINNIPEG IS PUSHING
COLDER AND EVEN DRIER LLVL AIR SWD...WITH H85 DWPT DOWN TO -21C/-27C
AT INL/YPL AT 00Z. H85 TEMPS WERE -6C AT INL BUT -18C AT THE PAS
MANITOBA JUST NW OF LK WINNIPEG. THE ARRIVAL OF THIS DRIER AIR IS
TENDING TO END THE PCPN OVER NRN MN EARLY THIS MRNG.
&&
.DISCUSSION...
MAIN FCST CONCERNS IN THE SHORT TERM ARE SN TRENDS/AMOUNTS AND
POTENTIAL FOR LES INTO TNGT. FOCUS IN THE LONGER TERM SHIFTS TO
POTENTIAL FOR MORE SN THIS COMING WEEKEND.
TDAY...EXPECT PERIODS OF -SN TO BE ONGOING AT FCST ISSUANCE MAINLY
OVER THE SE HALF OF THE CWA NEAR AXIS OF H85-7 FGEN AND BAND OF HIER
H85 DWPT CLOSER TO THE H85 FNT. ALTHOUGH THE ARRIVAL OF COLDER AIR
FM THE N...WITH H85 TEMPS FALLING TOWARD -9C AT 12Z OVER THE
KEWEENAW...WL BE SUFFICIENT TO GENERATE SOME LES...FAIRLY PROFOUND
DRYING IN THE H925-85 LYR AND GENERAL ACYC NATURE OF LLVL FLOW WL
TEND TO LIMIT THE DURATION AND INTENSITY OF THE SHSN. BEST CHC FOR
HIER LES ACCUMS LOOKS TO BE IN AN AREA FM MQT-MUNISING FAVORED BY
EXPECTED N WIND AND WHERE DEEPER MSTR IS PROGGED TO LINGER UNTIL
ABOUT NOON. LINGERING LES SHOULD DIMINISH FAIRLY STEADILY THIS AFTN
EVEN THOUGH QUITE A BIT OF SC SHOULD PERSIST WITH MOISTENING OFF LK
SUP. OTRW...EXPECT STEADY OR SLOWLY FALLING TEMPS THRU THE DAY WITH
THESE CLDS AND FALLING H85 TEMPS TO ARND -13C OVER THE NW LATER.
TNGT...WITH ARRIVAL OF SFC RDG AXIS/MORE ACYC BACKING FLOW...EXPECT
SKIES TO CLR OVER MOST OF THE CWA. THE LK CLDS WL BE MORE RESILIENT
OVER THE KEWEENAW AND E OF MUNISING IN AREAS EXPERIENCING OVERWATER
FETCH. ALSO KEPT LINGERING POPS FOR LES IN THESE AREAS...ESPECIALLY
OVER THE E WITH LONGER FETCH/MOISTENING TO OVERCOME DRY LLVLS. BUT
GENERAL DRYNESS/LARGER SCALE ACYC FLOW AS WELL AS GENERALLY POOR SN
GROWTH PARAMETER WITH DGZ ABV THE RELATIVELY SHALLOW MIXED LYR SUG
SN ACCUMS WL BE ON THE LGT SIDE. EXPECT THE LOWEST MIN TEMPS OVER
THE INTERIOR W HALF...WHERE THE LK MODERATION WL BE LEAST.
FRI...AS THE SFC HI PRES RDG SHIFTS TO THE E AND THE FLOW BACKS
SW... ANY LINGERING LES WL END IN THE MRNG AND GIVE WAY TO A GOOD
AMOUNT OF AFTN SUNSHINE. EVEN WITH THE GREATER INSOLATION...STABLE
NATURE OF FCST SDNGS WITHIN LLVL COLD AIR IN THE ARCTIC AIRMASS
INDICATES TEMPS WL NOT RISE ABV 32 AT MOST PLACES.
FRI NGT...STRONG SW FLOW BTWN HI PRES MOVING TOWARD NEW ENGLAND AND
APRCHG COLD FNT ATTENDANT TO SHRTWV/SFC LO TRACKING INTO HUDSON BAY
IS FCST TO DRAW MORE SGNFT MSTR TO THE N...WITH PWAT 150 TO 200 PCT
OF NORMAL BY 12Z. CONSIDERING THE STRONG SW FLOW /NAM SHOWS H85
WINDS UP TO 50 KTS/ AND MSTR RETURN...EXPECT MIN TEMPS TO BE HIER
THAN TNGT.
THIS WEEKEND...THE 00Z GFS/ECMWF AND 21Z SREF ARE IN GOOD AGREEMENT
ON INTERACTION BTWN ARCTIC BRANCH TROF IN CENTRAL CANADA AND
DISTURBANCE/MSTR WITHIN SRN BRANCH SW FLOW IN THE CONUS ON NW FLANK
OF UPR RDG OFF THE SE COAST. SO USED A BLEND OF THIS GUIDANCE TO
POPULATE GRIDS. THESE MODELS SHOW A LO PRES WAVE DVLPG ON FNT
PUSHING ACRS THE CWA SAT NGT...WITH CENTER OF LO PRES MOVING ACRS
NRN LK MI AND INTO SE ONTARIO ON SUN. TENDED TOWARD THE HIER LIKELY
POPS OVER THE SE HALF OF THE CWA...WHERE THE MODELS INDICATE AS MUCH
AS 3 TO 6 INCHES OF SN MAY ACCUMULATE ON SAT/SAT NGT UNDER UPR DVGC/
H85-7 FGEN IN RRQ OF JET MAX OVER ONTARIO IN CONFLUENCE ZN BTWN THE
2 BRANCES ON THE COLD SIDE OF SFC FRONTAL BNDRY...EVEN IF SOME RA
MIXES WITH THE PCPN NEAR LK MI. TENDED TO MAINTAIN HIER POPS ON SUN
OVER THE NCNTRL THAN INDICATED BY ALL BLEND GUIDANCE CONSIDERING THE
POTENTIAL FOR LINGERING LK ENHANCEMENT WITH SHARPER CYC NNW FLOW
SHOWN BY THE MOST CONSISTENT 00Z ECMWF.
&&
.AVIATION /FOR 18Z TAF ISSUANCE/
EXPECT THE CLOUDS TO LINGER THROUGH THE REMAINDER OF THIS AFTERNOON
AND INTO THE EARLY EVENING AS WINDS ARE NORTH TO NORTHWESTERLY OFF
THE LAKE. DRY AIR SEEN ON SATELLITE IS TRYING TO MAKE ITS WAY INTO
THE WESTERN TAF SITES...WITH A DISTINCT CLOUD EDGE MAINLY ALONG THE
WESTERN SHORES OF UPPER MICHIGAN. SOME LAKE EFFECT CLOUD COVER AND
POTENTIALLY SNOW SHOWERS WILL IMPACT KIWD THROUGH THE EARLY
AFTERNOON...THOUGH DO NOT EXPECT ANY SIGNIFICANT REDUCTION IN
VISIBILITIES. THIS IS PRIMARILY ASSOCIATED WITH A SHORTWAVE OVER THE
LAKE...AND LIMITED MOISTURE. ONCE THIS FEATURE PASSES LATE THIS
AFTERNOON AND DRY AIR MAKES ITS WAY INTO THE SITE...EXPECT CEILINGS
TO CLEAR OUT. KCMX WILL SEE A SIMILAR TREND...MINUS THE SNOW
SHOWERS. CONDITIONS SHOULD BE MVFR TO VFR TONIGHT AND THROUGH
TOMORROW AT THESE SITES. AS FOR KSAW...CONDITIONS WILL REMAIN RATHER
SOUPY UNTIL WINDS SWITCH AROUND TO THE NORTHWEST AFTER 00Z. UNTIL
THEN...THE SITE WILL HAVE TO DEAL WITH LIFR/IFR
VISIBILITIES/CEILINGS AND LAKE EFFECT SNOW SHOWERS. EXPECT THE CLOUD
COVER TO DIMINISH A LITTLE SLOWER THAN THE WESTERN SITES...HOWEVER
CONDITIONS SHOULD IMPROVE TO VFR FOR THE OVERNIGHT TIME PERIOD.
&&
.MARINE /FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE/...
AN ELONGATED LOW PRESSURE TROUGH FROM THE CENTRAL PLAINS TO FAR
EASTERN LAKE SUPERIOR WILL MOVE EAST TODAY. IN ITS WAKE...HIGH
PRESSURE OVER THE NORTHERN PLAINS WILL EXTEND A RIDGE OVER LAKE
SUPERIOR THROUGH FRIDAY MORNING...SINKING SOUTHEASTWARD TO THE
CENTRAL PLAINS. ON FRIDAY THE HIGH WILL MAKE ITS WAY TO THE
NORTHEASTERN STATES. MEANWHILE...LOW PRESSURE SYSTEM OVER HUDSON BAY
WILL DRAG A TROUGH ACROSS LAKE SUPERIOR SATURDAY AFTERNOON THROUGH
SATURDAY NIGHT. AHEAD OF THE TROUGH...EXPECT SOME SOUTHWEST GALE
FORCE GUSTS TO 35 KNOTS FRIDAY AFTERNOON INTO EARLY SATURDAY. HELD
OFF ON ISSUING ANY GALE HEADLINES SINCE GUSTS WILL ONLY MARGINALLY
MEET GALE CRITERIA. A LOW PRESSURE SYSTEM WILL TAKE SHAPE OVER THE
PLAINS SATURDAY NIGHT AND MERGE WITH THE TROUGH ON SUNDAY MORNING AS
IT REACHES LAKE MICHIGAN. THIS LOW WILL MOVE JUST EAST OF LAKE
SUPERIOR ON SUNDAY AFTERNOON AND REACH QUEBEC BY SUNDAY NIGHT.
ANOTHER LOW WILL DROP FROM ALBERTA INTO MINNESOTA SUNDAY
NIGHT...BEFORE MERGING WITH THE LINGERING TROUGH EAST OF LAKE
SUPERIOR BY MONDAY EVENING. THERE IS INCREASED UNCERTAINTY WITH
RESPECT TO WIND DIRECTIONS AND SPEEDS...AND THEREFOR WAVE HEIGHTS
STARTING SUNDAY EVENING. THE UNCERTAINTY IS DUE TO VARIABILITY
BETWEEN FORECAST MODELS ON THE TRACK AND STRENGTH OF THE LOW
PRESSURE SYSTEM COMING IN FROM THE WEST.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SYNOPSIS...KC
DISCUSSION...KC
AVIATION...MCB
MARINE...TITUS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
627 AM EST THU DEC 1 2011
UPDATED AVIATION DISCUSSION FOR 12Z TAFS
.SYNOPSIS...
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW WNW FLOW OVER THE
UPR GRT LKS BTWN TROFFING CENTERED OVER HUDSON BAY AND UPR RDG IN
THE SRN PLAINS. POSITIVELY TILTED SHRTWV IN THE NRN PLAINS MOVING
THRU THIS FLOW AND ASSOCIATED SFC LO PRES/COLD FNT STRETCHING FM
NCNTRL WI SWWD INTO THE CENTRAL PLAINS AT 04Z IS BRINGING AN AREA OF
SN TO THE UPR GRT LKS. MAIN FORCING MECHANISMS APPEAR TO BE UPR DVGC
IN EXIT REGION OF SUPPORTING 100KT H3 JET MAX AND BAND OF H85-7 FGEN
ASSOCIATED WITH FRONTAL ZN...BUT DRYNESS OF LLVLS PER NEARBY 00Z
RAOBS/LACK OF SGNFT ISENTROPIC ASCENT/MODEST DEEP LYR QVECTOR CNVGC
IS GENERALLY LIMITING THE OVERALL SN INTENSITY. TO THE NW...
SPRAWLING SFC HI PRES CENTERED JUST W OF LK WINNIPEG IS PUSHING
COLDER AND EVEN DRIER LLVL AIR SWD...WITH H85 DWPT DOWN TO -21C/-27C
AT INL/YPL AT 00Z. H85 TEMPS WERE -6C AT INL BUT -18C AT THE PAS
MANITOBA JUST NW OF LK WINNIPEG. THE ARRIVAL OF THIS DRIER AIR IS
TENDING TO END THE PCPN OVER NRN MN EARLY THIS MRNG.
&&
.DISCUSSION...
MAIN FCST CONCERNS IN THE SHORT TERM ARE SN TRENDS/AMOUNTS AND
POTENTIAL FOR LES INTO TNGT. FOCUS IN THE LONGER TERM SHIFTS TO
POTENTIAL FOR MORE SN THIS COMING WEEKEND.
TDAY...EXPECT PERIODS OF -SN TO BE ONGOING AT FCST ISSUANCE MAINLY
OVER THE SE HALF OF THE CWA NEAR AXIS OF H85-7 FGEN AND BAND OF HIER
H85 DWPT CLOSER TO THE H85 FNT. ALTHOUGH THE ARRIVAL OF COLDER AIR
FM THE N...WITH H85 TEMPS FALLING TOWARD -9C AT 12Z OVER THE
KEWEENAW...WL BE SUFFICIENT TO GENERATE SOME LES...FAIRLY PROFOUND
DRYING IN THE H925-85 LYR AND GENERAL ACYC NATURE OF LLVL FLOW WL
TEND TO LIMIT THE DURATION AND INTENSITY OF THE SHSN. BEST CHC FOR
HIER LES ACCUMS LOOKS TO BE IN AN AREA FM MQT-MUNISING FAVORED BY
EXPECTED N WIND AND WHERE DEEPER MSTR IS PROGGED TO LINGER UNTIL
ABOUT NOON. LINGERING LES SHOULD DIMINISH FAIRLY STEADILY THIS AFTN
EVEN THOUGH QUITE A BIT OF SC SHOULD PERSIST WITH MOISTENING OFF LK
SUP. OTRW...EXPECT STEADY OR SLOWLY FALLING TEMPS THRU THE DAY WITH
THESE CLDS AND FALLING H85 TEMPS TO ARND -13C OVER THE NW LATER.
TNGT...WITH ARRIVAL OF SFC RDG AXIS/MORE ACYC BACKING FLOW...EXPECT
SKIES TO CLR OVER MOST OF THE CWA. THE LK CLDS WL BE MORE RESILIENT
OVER THE KEWEENAW AND E OF MUNISING IN AREAS EXPERIENCING OVERWATER
FETCH. ALSO KEPT LINGERING POPS FOR LES IN THESE AREAS...ESPECIALLY
OVER THE E WITH LONGER FETCH/MOISTENING TO OVERCOME DRY LLVLS. BUT
GENERAL DRYNESS/LARGER SCALE ACYC FLOW AS WELL AS GENERALLY POOR SN
GROWTH PARAMETER WITH DGZ ABV THE RELATIVELY SHALLOW MIXED LYR SUG
SN ACCUMS WL BE ON THE LGT SIDE. EXPECT THE LOWEST MIN TEMPS OVER
THE INTERIOR W HALF...WHERE THE LK MODERATION WL BE LEAST.
FRI...AS THE SFC HI PRES RDG SHIFTS TO THE E AND THE FLOW BACKS
SW... ANY LINGERING LES WL END IN THE MRNG AND GIVE WAY TO A GOOD
AMOUNT OF AFTN SUNSHINE. EVEN WITH THE GREATER INSOLATION...STABLE
NATURE OF FCST SDNGS WITHIN LLVL COLD AIR IN THE ARCTIC AIRMASS
INDICATES TEMPS WL NOT RISE ABV 32 AT MOST PLACES.
FRI NGT...STRONG SW FLOW BTWN HI PRES MOVING TOWARD NEW ENGLAND AND
APRCHG COLD FNT ATTENDANT TO SHRTWV/SFC LO TRACKING INTO HUDSON BAY
IS FCST TO DRAW MORE SGNFT MSTR TO THE N...WITH PWAT 150 TO 200 PCT
OF NORMAL BY 12Z. CONSIDERING THE STRONG SW FLOW /NAM SHOWS H85
WINDS UP TO 50 KTS/ AND MSTR RETURN...EXPECT MIN TEMPS TO BE HIER
THAN TNGT.
THIS WEEKEND...THE 00Z GFS/ECMWF AND 21Z SREF ARE IN GOOD AGREEMENT
ON INTERACTION BTWN ARCTIC BRANCH TROF IN CENTRAL CANADA AND
DISTURBANCE/MSTR WITHIN SRN BRANCH SW FLOW IN THE CONUS ON NW FLANK
OF UPR RDG OFF THE SE COAST. SO USED A BLEND OF THIS GUIDANCE TO
POPULATE GRIDS. THESE MODELS SHOW A LO PRES WAVE DVLPG ON FNT
PUSHING ACRS THE CWA SAT NGT...WITH CENTER OF LO PRES MOVING ACRS
NRN LK MI AND INTO SE ONTARIO ON SUN. TENDED TOWARD THE HIER LIKELY
POPS OVER THE SE HALF OF THE CWA...WHERE THE MODELS INDICATE AS MUCH
AS 3 TO 6 INCHES OF SN MAY ACCUMULATE ON SAT/SAT NGT UNDER UPR DVGC/
H85-7 FGEN IN RRQ OF JET MAX OVER ONTARIO IN CONFLUENCE ZN BTWN THE
2 BRANCES ON THE COLD SIDE OF SFC FRONTAL BNDRY...EVEN IF SOME RA
MIXES WITH THE PCPN NEAR LK MI. TENDED TO MAINTAIN HIER POPS ON SUN
OVER THE NCNTRL THAN INDICATED BY ALL BLEND GUIDANCE CONSIDERING THE
POTENTIAL FOR LINGERING LK ENHANCEMENT WITH SHARPER CYC NNW FLOW
SHOWN BY THE MOST CONSISTENT 00Z ECMWF.
&&
.AVIATION /FOR 12Z TAF ISSUANCE/
EXPECT CLEARING CONDITIONS THROUGH THE TAF PERIOD AS DRY HIGH
PRESSURE WORKS INTO THE AREA FROM THE WEST. UNCERTAINTY REMAINS AS
TO EXACTLY WHEN LOW CLOUDS AND SNOW WILL END AT EACH OF THE
SITES...SO SOME ADJUSTMENTS OF THE END TIMES IN THE TAFS WILL LIKELY
BE NEEDED. HOWEVER...CONFIDENCE IS HIGH THAT ALL SITES WILL BE AT
LEAST MID AFTERNOON AT IWD AND CMX...AND BY THIS EVENING AT SAW.
&&
.MARINE /FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE/...
AN ELONGATED LOW PRESSURE TROUGH FROM THE CENTRAL PLAINS TO FAR
EASTERN LAKE SUPERIOR WILL MOVE EAST TODAY. IN ITS WAKE...HIGH
PRESSURE OVER THE NORTHERN PLAINS WILL EXTEND A RIDGE OVER LAKE
SUPERIOR THROUGH FRIDAY MORNING...SINKING SOUTHEASTWARD TO THE
CENTRAL PLAINS. ON FRIDAY THE HIGH WILL MAKE ITS WAY TO THE
NORTHEASTERN STATES. MEANWHILE...LOW PRESSURE SYSTEM OVER HUDSON BAY
WILL DRAG A TROUGH ACROSS LAKE SUPERIOR SATURDAY AFTERNOON THROUGH
SATURDAY NIGHT. AHEAD OF THE TROUGH...EXPECT SOME SOUTHWEST GALE
FORCE GUSTS TO 35 KNOTS FRIDAY AFTERNOON INTO EARLY SATURDAY. HELD
OFF ON ISSUING ANY GALE HEADLINES SINCE GUSTS WILL ONLY MARGINALLY
MEET GALE CRITERIA. A LOW PRESSURE SYSTEM WILL TAKE SHAPE OVER THE
PLAINS SATURDAY NIGHT AND MERGE WITH THE TROUGH ON SUNDAY MORNING AS
IT REACHES LAKE MICHIGAN. THIS LOW WILL MOVE JUST EAST OF LAKE
SUPERIOR ON SUNDAY AFTERNOON AND REACH QUEBEC BY SUNDAY NIGHT.
ANOTHER LOW WILL DROP FROM ALBERTA INTO MINNESOTA SUNDAY
NIGHT...BEFORE MERGING WITH THE LINGERING TROUGH EAST OF LAKE
SUPERIOR BY MONDAY EVENING. THERE IS INCREASED UNCERTAINTY WITH
RESPECT TO WIND DIRECTIONS AND SPEEDS...AND THEREFOR WAVE HEIGHTS
STARTING SUNDAY EVENING. THE UNCERTAINTY IS DUE TO VARIABILITY
BETWEEN FORECAST MODELS ON THE TRACK AND STRENGTH OF THE LOW
PRESSURE SYSTEM COMING IN FROM THE WEST.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SYNOPSIS...KC
DISCUSSION...KC
AVIATION...TITUS
MARINE...TITUS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
421 AM EST THU DEC 1 2011
.SYNOPSIS...
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW WNW FLOW OVER THE
UPR GRT LKS BTWN TROFFING CENTERED OVER HUDSON BAY AND UPR RDG IN
THE SRN PLAINS. POSITIVELY TILTED SHRTWV IN THE NRN PLAINS MOVING
THRU THIS FLOW AND ASSOCIATED SFC LO PRES/COLD FNT STRETCHING FM
NCNTRL WI SWWD INTO THE CENTRAL PLAINS AT 04Z IS BRINGING AN AREA OF
SN TO THE UPR GRT LKS. MAIN FORCING MECHANISMS APPEAR TO BE UPR DVGC
IN EXIT REGION OF SUPPORTING 100KT H3 JET MAX AND BAND OF H85-7 FGEN
ASSOCIATED WITH FRONTAL ZN...BUT DRYNESS OF LLVLS PER NEARBY 00Z
RAOBS/LACK OF SGNFT ISENTROPIC ASCENT/MODEST DEEP LYR QVECTOR CNVGC
IS GENERALLY LIMITING THE OVERALL SN INTENSITY. TO THE NW...
SPRAWLING SFC HI PRES CENTERED JUST W OF LK WINNIPEG IS PUSHING
COLDER AND EVEN DRIER LLVL AIR SWD...WITH H85 DWPT DOWN TO -21C/-27C
AT INL/YPL AT 00Z. H85 TEMPS WERE -6C AT INL BUT -18C AT THE PAS
MANITOBA JUST NW OF LK WINNIPEG. THE ARRIVAL OF THIS DRIER AIR IS
TENDING TO END THE PCPN OVER NRN MN EARLY THIS MRNG.
&&
.DISCUSSION...
MAIN FCST CONCERNS IN THE SHORT TERM ARE SN TRENDS/AMOUNTS AND
POTENTIAL FOR LES INTO TNGT. FOCUS IN THE LONGER TERM SHIFTS TO
POTENTIAL FOR MORE SN THIS COMING WEEKEND.
TDAY...EXPECT PERIODS OF -SN TO BE ONGOING AT FCST ISSUANCE MAINLY
OVER THE SE HALF OF THE CWA NEAR AXIS OF H85-7 FGEN AND BAND OF HIER
H85 DWPT CLOSER TO THE H85 FNT. ALTHOUGH THE ARRIVAL OF COLDER AIR
FM THE N...WITH H85 TEMPS FALLING TOWARD -9C AT 12Z OVER THE
KEWEENAW...WL BE SUFFICIENT TO GENERATE SOME LES...FAIRLY PROFOUND
DRYING IN THE H925-85 LYR AND GENERAL ACYC NATURE OF LLVL FLOW WL
TEND TO LIMIT THE DURATION AND INTENSITY OF THE SHSN. BEST CHC FOR
HIER LES ACCUMS LOOKS TO BE IN AN AREA FM MQT-MUNISING FAVORED BY
EXPECTED N WIND AND WHERE DEEPER MSTR IS PROGGED TO LINGER UNTIL
ABOUT NOON. LINGERING LES SHOULD DIMINISH FAIRLY STEADILY THIS AFTN
EVEN THOUGH QUITE A BIT OF SC SHOULD PERSIST WITH MOISTENING OFF LK
SUP. OTRW...EXPECT STEADY OR SLOWLY FALLING TEMPS THRU THE DAY WITH
THESE CLDS AND FALLING H85 TEMPS TO ARND -13C OVER THE NW LATER.
TNGT...WITH ARRIVAL OF SFC RDG AXIS/MORE ACYC BACKING FLOW...EXPECT
SKIES TO CLR OVER MOST OF THE CWA. THE LK CLDS WL BE MORE RESILIENT
OVER THE KEWEENAW AND E OF MUNISING IN AREAS EXPERIENCING OVERWATER
FETCH. ALSO KEPT LINGERING POPS FOR LES IN THESE AREAS...ESPECIALLY
OVER THE E WITH LONGER FETCH/MOISTENING TO OVERCOME DRY LLVLS. BUT
GENERAL DRYNESS/LARGER SCALE ACYC FLOW AS WELL AS GENERALLY POOR SN
GROWTH PARAMETER WITH DGZ ABV THE RELATIVELY SHALLOW MIXED LYR SUG
SN ACCUMS WL BE ON THE LGT SIDE. EXPECT THE LOWEST MIN TEMPS OVER
THE INTERIOR W HALF...WHERE THE LK MODERATION WL BE LEAST.
FRI...AS THE SFC HI PRES RDG SHIFTS TO THE E AND THE FLOW BACKS
SW... ANY LINGERING LES WL END IN THE MRNG AND GIVE WAY TO A GOOD
AMOUNT OF AFTN SUNSHINE. EVEN WITH THE GREATER INSOLATION...STABLE
NATURE OF FCST SDNGS WITHIN LLVL COLD AIR IN THE ARCTIC AIRMASS
INDICATES TEMPS WL NOT RISE ABV 32 AT MOST PLACES.
FRI NGT...STRONG SW FLOW BTWN HI PRES MOVING TOWARD NEW ENGLAND AND
APRCHG COLD FNT ATTENDANT TO SHRTWV/SFC LO TRACKING INTO HUDSON BAY
IS FCST TO DRAW MORE SGNFT MSTR TO THE N...WITH PWAT 150 TO 200 PCT
OF NORMAL BY 12Z. CONSIDERING THE STRONG SW FLOW /NAM SHOWS H85
WINDS UP TO 50 KTS/ AND MSTR RETURN...EXPECT MIN TEMPS TO BE HIER
THAN TNGT.
THIS WEEKEND...THE 00Z GFS/ECMWF AND 21Z SREF ARE IN GOOD AGREEMENT
ON INTERACTION BTWN ARCTIC BRANCH TROF IN CENTRAL CANADA AND
DISTURBANCE/MSTR WITHIN SRN BRANCH SW FLOW IN THE CONUS ON NW FLANK
OF UPR RDG OFF THE SE COAST. SO USED A BLEND OF THIS GUIDANCE TO
POPULATE GRIDS. THESE MODELS SHOW A LO PRES WAVE DVLPG ON FNT
PUSHING ACRS THE CWA SAT NGT...WITH CENTER OF LO PRES MOVING ACRS
NRN LK MI AND INTO SE ONTARIO ON SUN. TENDED TOWARD THE HIER LIKELY
POPS OVER THE SE HALF OF THE CWA...WHERE THE MODELS INDICATE AS MUCH
AS 3 TO 6 INCHES OF SN MAY ACCUMULATE ON SAT/SAT NGT UNDER UPR DVGC/
H85-7 FGEN IN RRQ OF JET MAX OVER ONTARIO IN CONFLUENCE ZN BTWN THE
2 BRANCES ON THE COLD SIDE OF SFC FRONTAL BNDRY...EVEN IF SOME RA
MIXES WITH THE PCPN NEAR LK MI. TENDED TO MAINTAIN HIER POPS ON SUN
OVER THE NCNTRL THAN INDICATED BY ALL BLEND GUIDANCE CONSIDERING THE
POTENTIAL FOR LINGERING LK ENHANCEMENT WITH SHARPER CYC NNW FLOW
SHOWN BY THE MOST CONSISTENT 00Z ECMWF.
&&
.AVIATION /FOR 06Z TAF ISSUANCE/
NORTHERLY WINDS TO INCREASE OVERNIGHT AS HIGH PRESSURE BUILDS INTO
THE REGION BEHIND EXITING LOW PRESSURE TROUGH. AT FORECAST
ISSUANCE...TRANSITION FROM SYNOPTIC SNOWFALL TO LES OCCURRING AS
WINDS BECOME NORTHERLY. AT KIWD...CIGS TO HOLD IN MVFR THROUGH 12Z
WHILE KSAW AND KCMX TO SEE CIGS TO BOUNCE BETWEEN MVFR AND VFR WITH
DEVELOPING LES. OCCASIONAL IFR VSBYS EXPECTED AT BOTH KIWD AND KCMX
WITH LES DEVELOPMENT. INTRUSION OF DRIER AIR AND LOWERING OF
INVERSION HEIGHTS AS COLD AIR ADVECTION INCREASES SHOULD BRING AN
END TO THE -SHSN BY 12Z OUT WEST AND SHORTLY THEREAFTER AT KSAW.
AFTER 12Z...VFR CONDITIONS TO PREVAIL AT ALL SITES THROUGH THE END
OF THE FORECAST.
&&
.MARINE /FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE/...
AN ELONGATED LOW PRESSURE TROUGH FROM THE CENTRAL PLAINS TO FAR
EASTERN LAKE SUPERIOR WILL MOVE EAST TODAY. IN ITS WAKE...HIGH
PRESSURE OVER THE NORTHERN PLAINS WILL EXTEND A RIDGE OVER LAKE
SUPERIOR THROUGH FRIDAY MORNING...SINKING SOUTHEASTWARD TO THE
CENTRAL PLAINS. ON FRIDAY THE HIGH WILL MAKE ITS WAY TO THE
NORTHEASTERN STATES. MEANWHILE...LOW PRESSURE SYSTEM OVER HUDSON BAY
WILL DRAG A TROUGH ACROSS LAKE SUPERIOR SATURDAY AFTERNOON THROUGH
SATURDAY NIGHT. AHEAD OF THE TROUGH...EXPECT SOME SOUTHWEST GALE
FORCE GUSTS TO 35 KNOTS FRIDAY AFTERNOON INTO EARLY SATURDAY. HELD
OFF ON ISSUING ANY GALE HEADLINES SINCE GUSTS WILL ONLY MARGINALLY
MEET GALE CRITERIA. A LOW PRESSURE SYSTEM WILL TAKE SHAPE OVER THE
PLAINS SATURDAY NIGHT AND MERGE WITH THE TROUGH ON SUNDAY MORNING AS
IT REACHES LAKE MICHIGAN. THIS LOW WILL MOVE JUST EAST OF LAKE
SUPERIOR ON SUNDAY AFTERNOON AND REACH QUEBEC BY SUNDAY NIGHT.
ANOTHER LOW WILL DROP FROM ALBERTA INTO MINNESOTA SUNDAY
NIGHT...BEFORE MERGING WITH THE LINGERING TROUGH EAST OF LAKE
SUPERIOR BY MONDAY EVENING. THERE IS INCREASED UNCERTAINTY WITH
RESPECT TO WIND DIRECTIONS AND SPEEDS...AND THEREFOR WAVE HEIGHTS
STARTING SUNDAY EVENING. THE UNCERTAINTY IS DUE TO VARIABILITY
BETWEEN FORECAST MODELS ON THE TRACK AND STRENGTH OF THE LOW
PRESSURE SYSTEM COMING IN FROM THE WEST.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SYNOPSIS...KC
DISCUSSION...KC
AVIATION...RJT
MARINE...TITUS
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1149 PM CST WED NOV 30 2011
.AVIATION... /06Z TAF ISSUANCE/
SNOW IS SINKING SOUTHEAST IN THE WAKE OF THE COLD FRONT A LITTLE
FASTER THAN PREVIOUSLY FORECAST. HAVE SPED UP THE LOW MVFR
CEILINGS AND VISIBILITIES INTO KRWF-KMSP-KEAU AS A RESULT. THE
BAND OF SNOW WILL SHIFT SOUTH OF THE TWIN CITIES BY 12Z BUT
CONTINUE ACROSS KEAU THROUGH 15Z. MVFR CEILINGS WILL BREAKUP FROM
NORTHWEST TO SOUTHEAST FROM LATE MORNING THROUGH THE EARLY
AFTERNOON AS STRONG LOW LEVEL RIDGING BUILDS IN. NORTH TO
NORTHWEST WINDS THURSDAY MORNING AROUND 12 KNOTS WITH GUSTS TO 18
KNOTS. LIGHT WEST WINDS AND SKC FOR THURSDAY NIGHT.
KMSP...BEST FORCING WILL BE MOVING ACROSS THE AIRFIELD THROUGH
09Z. LOW MVFR CEILINGS LIKELY ALONG WITH 2SM -SN BR. SOME THREAT
FOR CEILINGS TO INTERMITTENTLY DROP BELOW 010 THROUGH DAYBREAK.
CONDITIONS IMPROVING FROM MID MORNING ONWARD AS RIDGING BUILDS
IN. WINDS WILL BE THE STRONGEST DURING THE MORNING WITH NORTH AT
15 KNOTS COMMON. SKC WITH LIGHT WNW WINDS THURSDAY NIGHT.
&&
.DISCUSSION... /ISSUED 312 PM CST WED NOV 30 2011/
TONIGHT THROUGH THURSDAY...AT THE SFC A WEAK COLD FRONT WILL
SLOWLY GLIDE S ACRS SRN MN/SW WI THROUGH THE OVERNIGHT HOURS INTO
THU MRNG. AS IT DROPS S...A RELATIVELY WEAK AREA OF LOW PRESSURE
IS EXPECTED TO DEVELOP ALONG IN INVOF MN/IA BORDER. FAIRLY DEEP
MOISTURE...AS SHOWN BY AN EXTENSIVE CLOUD SHIELD ON VIS SAT
IMAGERY AND RATHER MOIST RUC SOUNDINGS...IS AVAILABLE FOR A DECENT
MIDLVL SHORTWAVE TROUGH AXIS TO PRODUCE PRECIP MAINLY AFTER
MIDNIGHT AND THROUGH SUNRISE. TAKING THE FORM OF ALL SNOW... WILL
LOOK FOR ENOUGH QPF TO PRODUCE ONE HALF TO ONE AND A HALF INCHES
OF SNOW WITH THE HEAVIEST OF THE SNOW OCCURRING DURING THE MORNING
COMMUTE HOURS. THE GREATER OF THE SNOW ACCUMULATIONS WILL EAST AND
SOUTH OF THE TWIN CITIES METRO. ALTHOUGH CONVECTIVE SNOWS ARE NOT
APPARENT ON EVEN SHORT-TERM MODELS PARTICULARLY WITH SFC
CONVERGENCE AND LIFT RATHER WEAK...THE UPPER LEVEL SUPPORT
AVAILABLE DOES NOT RULE OUT AN ISOLATED BURST OF HEAVIER SNOW THAT
COULD PRODUCE UP TO 2 INCHES IN A SHORT AMOUNT OF TIME...MAINLY
OVER WRN WI WHERE JET DYNAMICS LOOK TO POTENTIALLY ENHANCE PRECIP
THURSDAY MORNING. THE PRECIP WILL GRADUALLY TAPER OFF DURING THE
LATE MORNING THROUGH AFTERNOON HOURS TOMORROW WITH VERY LITTLE
LEFT BY LATE AFTERNOON. AS FOR TEMPERATURES...THE POTENT COLD
FRONT WILL EFFICIENTLY LEAD THE WAY FOR H85 TEMPS IN THE -7 TO -10
DEG C RANGE TO DROP THROUGH THE REGION DURING THE DAY TOMORROW...
MAKING FOR A VERY SMALL DIURNAL RANGE FROM LOW TEMPS TONIGHT TO
HIGHS TMRW. LOWS TONIGHT WILL RANGE FROM THE LWR 20S NW TO AROUND
30 SE AND IN THE METRO...FOLLOWED BY HIGHS THU FROM THE MID 20S NW
TO THE LWR 30S SE.
THURSDAY NIGHT THROUGH SUNDAY...SKIES WILL SLOWLY CLEAR OUT THU
NIGHT INTO FRI THE UPPER LEVEL TROUGH DROPS S OF THE REGION AND A
BUBBLE HIGH PRES RIDGE MOVES ACROSS THE NRN PLAINS INTO THE GREAT
LAKES. AT THE SFC...A SPOKE OF HIGH PRES EXTENDING NE FROM THE
CENTRAL PLAINS WILL ROTATE THROUGH...ALLOWING FOR DECENT
RADIATIONAL COOLING CONDITIONS THU NIGHT AS WINDS DROP TO BELOW 7
MPH. LOWS WILL FALL TO THE UPPER SINGLE DIGITS TO THE MID TEENS.
EVEN WITH THE CLEAR SKIES CONTINUING ON FRI AND SFC FLOW TURNING
MORE SLY...NW TO W UPPER FLOW AND H85 TEMPS ARND -5 DEG C WILL
KEEP HIGHS ON FRI JUST BELOW FREEZING. THE WEATHER STORY BECOMES
VERY INTERESTING FRI NIGHT THROUGH SAT NIGHT AS AS UPPER LEVEL LOW
CHURNING IN THE SOUTHWEST BECOMES CAUGHT UP IN A NORTHERN STREAM
LONGWAVE TROUGH AXIS PUSHING THRU WRN CANADA AND THE NRN PLAINS
STATES. BOTH UPPER SYSTEMS INTERACT BUT IN PIECES...AND A FEW
PIECES OF ENERGY WILL SHIFT NE FROM THE SOUTHWEST TWD THE GREAT
LAKES SAT AS CYCLOGENESIS OCCURS OVER THE TX PANHANDLE. THIS
NEWLY-GENERATED SFC LOW WILL RACE NE LATE SATURDAY THROUGH SAT
NIGHT BUT THE BIGGER PROBLEM IS HOW CLOSE AN UPPER SHORTWAVE
TROUGH AXIS COMES TO INTERACT WITH IT. MOISTURE TRANSPORT AHEAD OF
THIS NEW SFC LOW INCREASES AND THE INCOMING UPPER TROUGH WILL
ENHANCE LIFT. GIVEN THE COLD TEMPERATURES IN PLACE...P-TYPE ISSUES
WILL NOT BE PRESENT FOR THE WFO MPX CWFA AS PRECIP WOULD BE ALL
SNOW. THERE IS STILL MUCH MODEL DISAGREEMENT IN THE PLACEMENT OF
THE MAIN PLAYERS INVOLVED...AND THIS IS RELAYED VIA MODEL SNOWFALL
ACCUMS WHICH COULD BE UP TO A COUPLE OF INCHES TO OVER 6 INCHES
WITH THE HIGHEST AMOUNTS FOR SOUTHERN AND EASTERN PORTIONS OF THE
COVERAGE AREA. HAVE NUDGED POPS INTO THE LIKELY CATEGORY FOR THOSE
AREAS...TRENDING DOWN GOING WEST AND NORTH...AND HAVE KEPT
SNOWFALL AMOUNTS CAPPED AT 4 INCHES FOR FAR SRN AND ERN FRINGES
WITH NO SNOW EXPECTED FOR THE NWRN TIERS. THIS SYSTEM QUICKLY
EJECTS TO THE E SAT NIGHT INTO SUN...ALLOWING FOR AT LEAST PARTIAL
CLEARING DURING THE DAY SUNDAY BEFORE ANOTHER AREA OF LOW PRESSURE
DROPS IN FROM MANITOBA LATE SUN INTO SUN NIGHT. THERE IS POTENTIAL
FOR VERY LIGHT ACCUMS OVER NRN TIERS OF THE COVERAGE AREA BUT WITH
SO MUCH UNCERTAINTY WITH THIS SATURDAY SYSTEM...IT IS DIFFICULT TO
PINPOINT THINGS WITH THE LATE SUNDAY SYSTEM SO HAVE KEPT POPS IN
THE SLGT CHC CATEGORY. TEMPERATURES WILL RUN NEAR TO SLIGHTLY
ABOVE NORMAL THRU FRI...THEN DROP TO SLIGHTLY BELOW NORMAL OVER
THE WEEKEND.
MONDAY THROUGH WEDNESDAY...THE AFOREMENTIONED LOW ON SUNDAY WILL
MOVE INTO THE GREAT LAKES MONDAY...FOLLOWED BY RIDGING BOTH AT THE
SFC AND ALOFT FOR THE START OF NEXT WEEK. COLDER PUNCHES OF AIR
DROPPING S FROM NRN-CENTRAL CANADA WILL KEEP TEMPS BELOW NORMAL
FOR THE FIRST HALF OF NEXT WEEK. HAVE KEPT A PREDOMINANTLY DRY
FORECAST GOING DUE TO THE LACK OF BONA FIDE SYSTEMS PROGGED FOR
THIS PERIOD.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
RAH/TRH
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
1030 PM EST FRI DEC 2 2011
.SYNOPSIS...
A WEAK DRY COLD FRONT MOVE THROUGH THE AREA THEN DISSIPATE TONIGHT.
HIGH PRESSURE IN THE OHIO VALLEY WILL MOVE INTO THE MID-ATLANTIC
SATURDAY THEN OFF THE COAST SATURDAY NIGHT. A COLD FRONT WILL MOVE
THROUGH FROM THE WEST WEDNESDAY NIGHT.
&&
.NEAR TERM /THROUGH SATURDAY/...
AS OF 10 PM FRI...UPDATED WIND AND TEMP GRIDS TO REFLECT CURRENT
CONDITIONS. USED A SHARP DIURNAL DROP OFF FOR THE TEMPS THROUGH
LATE EVENING...LEVELING OFF AFTER AROUND MIDNIGHT. TEMPS HAVE
REACHED THEIR MINS IN MANY LOCALES...AS T-TD SPREADS ARE NEAR 0. WINDS
ALONG COASTAL AREAS INC OBX HAVE BECOME CALM...ALLOWING FOR TEMPS
TO RADIATE OUT THERE AS WELL. STILL EXPECTING MIN T`S TO DROP
SEVERAL DEGREES BELOW GUIDANCE WITH LOW 30S INLAND TO NEAR 40
IMMEDIATE COASTAL AREAS.
SFC HIGH PRESSURE WILL CONTINUE TO MOVE E TONIGHT...MOVING INTO
THE MID-ATLANTIC. ANOTHER COOL NIGHT ON TAP FOR EASTERN NC WITH
CLEAR SKIES AND LIGHT WINDS...THOUGH NOT AS COLD AS LAST NIGHT.
OVERNIGHT LOWS LIKELY IN THE LOWER TO MIDDLE 30S INLAND...AND
UPPER 30S TO MID 40S ALONG THE COAST AND OBX.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH 6 PM SATURDAY/...
AS OF 2 PM FRI...SFC HIGH PRESSURE WILL MOVE OVER THE MID-ATLANTIC
AND EXTEND INTO THE SE US SAT. LOW LEVEL THICKNESS VALUES...MOSTLY
SUNNY SKIES...AND LOW LEVEL N/NE FLOW SUPPORT HIGH TEMPS IN THE
UPPER 50S TO LOWER 60S...VERY SIMILAR TO FRI.
&&
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
AS OF 130 PM FRIDAY...MID/UPR RDG WILL BUILD JUST OFF THE COAST
THROUGH EARLY NEXT WEEK AS SFC HIGH TO THE N WEAKENS AND SHIFTS E.
THIS WILL LEAD TO MOSTLY DRY WX WITH WARMING TREND THROUGH TUE.
HIGHS SUNDAY WILL REACH MID 60S THEN AROUND 70 INLAND MON AND TUE.
AS LOW LVL FLOW BECOMES MORE SE LATER MON AND TUE CANT RULE OUT
SOME VERY SHALLOW SHRA PER MOIST LOW LVLS BUT LIMITED FORCING AND
SHALLOW NATURE OF MOISTURE SHLD PRECLUDE MUCH IF ANY PRECIP.
BETTER RAIN CHCS WED INTO WED NIGHT AS COLD FRONT APPROACHES AND
CROSSES. MDLS DIFFER AS USUAL WITH GFS FASTER...BASED ON HPC WILL
LEAN MORE TWRD ECMWF WITH SLOWER FROPA AND CONT CHC POPS INTO WED
NIGHT AND EARLY THU CST. WITH SLOWER FROPA EXPECT WED TO REMAIN
MILD WITH HIGHS WELL INTO THE 60S. ONCE FRONT CLEARS CST EXPECT
DRY AND NEAR TO SLIGHTLY BELOW NORMAL TEMPS FRI.
&&
.AVIATION /04Z SATURDAY THROUGH WEDNESDAY/...
SHORT TERM /THROUGH SATURDAY/...
AS OF 7 PM FRI...MAINLY VFR CONDS THROUGH THE TAF PD. NOT AS
CONFIDENT ON FOG FORMATION OVERNIGHT AS COMPARED TO LAST NIGHT...AS
LOW LEVEL WINDS EXPECTED TO PICK UP A BIT AFT 06Z AS SFC COLD
FRONT DROPS IN FROM THE NORTH. THAT SAID...WILL HAVE TO MONITOR
VWP OVERNIGHT TO DETERMINE STRENGTH OF THE NOCTURNAL INVERSION AND
POTENTIAL FOR FOG. OTHERWISE...EXPECTING NORTH WINDS UP TO 10 KT
ON SAT WITH JUST SOME HIGH CLOUDS STREAMING THROUGH FROM THE WEST.
LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 130 PM FRIDAY...OUTSIDE OF TYPICAL PATCHY LATE NIGHT
FOG/STRATUS THREAT EXPECT VFR THROUGH SUN NIGHT. AS LOW LVL FLOW
BECOMES MORE ONSHORE MON AND TUE WILL LIKELY SE MORE CLOUDS WITH
CIGS OCNLY BELOW VFR ESPCLY LATE NIGHT/EARLY MORN. PRECIP CHC WILL
INCREASE WED AHEAD OF FRONT WITH SCT REDUCED CIGS/VSBYS.
&&
.MARINE...
SHORT TERM /THROUGH SATURDAY/...
AS OF 10 PM FRI...DELAYED ONSET OF NORTHERLY SURGE OF WINDS AS
MOST LOCALES THROUGH LATE EVENING HAVE BEEN LIGHT AND VAR. NEAR
TERM GUIDANCE FROM HRRR AND RUC DO SHOW THE NORTHERLY SURGE OF 15+
KT WINDS ARRIVING AFTER 06Z WITH WINDS INC TO UP TO 20 KT FROM
NORTH TO SOUTH ALONG THE NC COASTAL WATERS. OCNL GUSTS TO 25 KT
EXPECTED FOR THE COASTAL WATERS WITH 20-25 KT FOR EASTERN PORTIONS
OF THE SOUNDS. SEAS BUILDING TOWARDS SCA FOR THE NORTHERN WATERS.
WILL LEAVE SCA HEADLINES AS IS.
LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 130 PM FRIDAY...WINDS WILL BE DIMINISHING SAT NIGHT AS
STRONG HIGH TO THE N WEAKENS AND DRIFTS E...SPEEDS SHLD BE 10 KT
OR LESS BY SUNDAY MORN. LIGHT E TO NE WINDS WILL CONT SUNDAY AND
SUNDAY NIGHT WITH THE HIGH TO THE NE. WIND DIR WILL BECOME MORE SE
MON AND MON NIGHT THEN S TUE AS COLD FRONT APPROACHES FROM THE W.
SPEEDS WILL REMAIN LESS THAN 15 KTS THROUGH TUE. S/SW WINDS WILL
INCREASE TO 15 OR 15 TO 20 KTS WED AHEAD OF COLD FRONT. SCA SEAS
WILL CONT MOST WTRS SAT EVENING THEN SHLD SUBSIDE BELOW 6 FT ALL
BUT CNTRL WTRS AND EXPECT THESE WTRS TO DROP BELOW 6 FT SUNDAY.
WILL KEEP SEAS CAPPED AT 5 FT SUN NIGHT THRU TUE NIGHT WITH LIGHT
WINDS...WAVEWATCH DOES SHOW NICE E SWELL AND SEAS THAT WILL FLIRT
WITH 6 FT FAR OUTER CNTRL WTRS...BUT SINCE SO MARGINAL FEEL BEST
NOT TO EXTENDED SCA OUT PAST SUNDAY. AS S/SW WINDS INCREASE WED
SEAS COULD AGAIN REACH SCA LVLS.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 1 PM EST SUNDAY FOR AMZ152-154.
SMALL CRAFT ADVISORY FROM 9 AM SATURDAY TO 5 AM EST SUNDAY FOR
AMZ158.
SMALL CRAFT ADVISORY FROM 5 AM SATURDAY TO 5 AM EST SUNDAY FOR
AMZ156.
SMALL CRAFT ADVISORY FROM 2 AM SATURDAY TO 5 AM EST SUNDAY FOR
AMZ150.
&&
$$
SYNOPSIS...CQD
NEAR TERM...TL/CQD
SHORT TERM...CQD
LONG TERM...RF
AVIATION...TL/RF
MARINE...TL/RF
AREA FORECAST DISCUSSION...UPDATED
NWS GRAND FORKS ND
1044 AM CST THU DEC 1 2011
.DISCUSSION...
THE MAIN ISSUE IS AREA OF CLOUDS IN CNTRL-WRN ND AND HOW FAR THEY
WILL ADVANCE EAST. AREA OF 2500-3500 FT AGL CLOUDS CONTINUES TO
SPREAD EAST-SOUTHEAST THRU SE SASK INT MANITOBA AND EXTENDS INTO
THE CNTRL PARTS OF ND. MOVEMENT IS EAST AND CLOUDS WOULD SPREAD
INTO THE NRN VALLEY MIDDAY-EARLY AFTN. SRN EDGE OF THE CLOUD AREA
IS MUCH MORE SPOTTY THAN THE NORTH END. LATEST VSBL PIX AND
WEBCAMS SHOWS CLOUDS ARE NOT COMPLETELY SOLID WITH SOME HOLES
FORMING. ALL IN ALL...CONFIDENCE IN THESE CLOUDS...HOW FAR THEY
WILL ADVANCE AND OVERALL EVOLUTION IS LOWER THAN NORMAL. CANT FIND
A REAL MECHANISM WHY THEY ARE THERE. RUC AND 11Z HRRR DO FINALLY
PICK UP ON SOME 925-850 MB MOISTURE ON THE NOSE OF 925-850 MB WARM
ADVECTION. THIS DOES SPREAD IN THE VALLEY..ESP NRN VALLEY...THIS
AFTN. WILL UPDATE GRIDDS FOR THIS IDEA...BUT TRY TO BREAK IT UP SOME.
WILL NOT ALTER TEMPS RIGHT NOW AS WITHOUT SNOWCOVER TEMPS HAVE
BEEN FORECASTING TOO COLD OF LATE.
&&
AVIATION...
WILL NEED TO WATCH HIGH END MVFR-LOW END VFR CLOUDS IN CNTRL ND
THIS AFTN. THEY MOVED INTO DVL AND SHOULD REMAIN AT LEAST IN A
SCT-BKN PHASE TODAY AND POSSIBLY MOVE INTO GFK TOWARD 18-19Z.
&&
.PREV DISCUSSION... /ISSUED 330 AM CST THU DEC 1 2011/
SHORT TERM...
TEMPERATURES AND WINDS ON FRIDAY WILL BE THE PRIMARY FORECAST
ISSUES.
NORTHERLY WINDS ON THE FRONT SIDE OF THE SFC HIGH OVER THE
NORTHERN ROCKIES AND PLAINS WILL CONTINUE TO BRING DRY AIR AT LOW
LEVELS INTO THE CWA THIS MORNING. CLOUDS HAVE BEEN
DECREASING...ALTHOUGH THERE HAS BEEN AN AREA OF STRATUS MOVING
INTO NORTHWESTERN ND FROM CANADA. THE SFC HIGH WILL MOVE SOUTH
THROUGH TODAY AS THE NORTHERN BRANCH SHORTWAVE TROUGH PUSHES
FURTHER EAST. EVEN WITH THE DECREASING CLOUDS...850MB TEMPS IN THE
-10 TO -13 C RANGE WILL KEEP US COOL...PARTICULARLY IN THE
NORTHEASTERN CWA. THE WESTERN COUNTIES MAY BE A BIT WARMER...IN
THE MID TO UPPER 20S...AS WINDS SHIFT TO THE WEST BY AFTERNOON AND
START TO BRING IN SOME WARMER AIR.
TONIGHT...SFC LOW PRESSURE WITH STRENGTHEN OVER SASKATCHEWAN AND
MANITOBA. WINDS WILL INCREASE AGAIN OUT OF THE SOUTHWEST AND
SHOULD KEEP THE BOUNDARY LAYER MIXED IN THE WEST...WHILE GREATER
DECOUPLING IN THE EAST WILL ALLOW TEMPS TO DROP BELOW 10 F IN SOME
PLACES. THE SFC TROUGH WILL CONTINUE INTO FRIDAY...WITH STRONG
SOUTHWESTERLY WINDS. THIS WILL HELP TEMPS GET BACK INTO THE 30S.
NAM AND GFS BOTH HAVE 925MB WINDS GETTING UP ABOVE 40 KTS IN THE
NORTHERN RED RIVER VALLEY BY FRIDAY AFTERNOON. WILL HAVE TO WATCH
THE AREA FOR WINDS APPROACHING ADVISORY CRITERIA.
ANOTHER SHORTWAVE TROUGH WILL MOVE THROUGH THE NORTHERN PLAINS ON
FRIDAY NIGHT...PUSHING THE SFC LOW EAST AND BRINGING A COLD FRONT
THROUGH THE CWA. THE 00Z AND TO A LESSER EXTENT THE 06Z NAM
BREAK OUT PRECIP AHEAD OF THE FRONT FRIDAY NIGHT. THE GLOBAL
MODELS ARE MUCH MORE DRY. WILL KEEP POPS SILENT FOR NOW FRIDAY
NIGHT BUT WILL MONITOR FOR FURTHER DEVELOPMENTS. THERE ARE MORE
INDICATIONS OF SOME LIGHT PRECIP IN THE LAKE OF THE WOODS REGION
SATURDAY AFTERNOON AS THE SYSTEM MOVES OFF THROUGH CANADA...SO
WILL KEEP THE LOW POPS WE HAD GOING IN THAT AREA. THE NEXT SYSTEM
WILL START DIGGING INTO THE MT/ND BORDER SATURDAY NIGHT...WITH THE
SFC LOW DROPPING DOWN INTO WESTERN ND.
LONG TERM...
THE SFC LOW WILL MOVE INTO THE AREA ON SUNDAY...SO CONTINUED WITH
CHANCE POPS FOR SNOW OVER MUCH OF THE CWA. AFTER A BRIEF BREAK
DURING THE EARLY PART OF THE WORK WEEK...ANOTHER FRONTAL BOUNDARY
MOVING THROUGH WILL BRING A CHANCE FOR PRECIP TO THE SOUTHERN
COUNTIES WEDNESDAY NIGHT SO INCLUDED SOME LOW POPS.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
RIDDLE/JR
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
814 PM CST FRI DEC 2 2011
.UPDATE...
MIN TEMPS IN THE EASTERN ZONES WERE A BIT TOO LOW BASED ON CURRENT
TRENDS AND RAISED THEM ABOUT 5 DEGREES. CURRENT TEMPERATURES WEST
OF I-35 ARE MOST LIKELY GOING TO BE NEAR THE LOWS FOR THE NIGHT
DUE TO WARMER TEMPERATURES EXPECTED AS THE FRONTAL BOUNDARY
CONTINUES TO LIFT NORTHWEST/WASH OUT AND THE HOURLY GRIDS NOW
REFLECT THIS.
VISIBILITIES HAVE IMPROVED ALONG THE INTERSTATE 35 CORRIDOR DUE TO
THE FRONT SHIFTING NORTHWEST AND HAVE CANCELED THE DENSE FOG
ADVISORY FOR THIS LOCATION. ADDITIONAL IMPROVEMENT IS EXPECTED
FROM EAST TO WEST THIS EVENING ACROSS THE REST OF THE ADVISORY
AREA. UPDATED THE WORDING OF THE ZONES AND THE HAZARD GRIDS TO
REFLECT THE LATEST CHANGES.
85/NH
&&
.AVIATION...
WARM FRONT SLOWLY MOVING NORTHWEST IS CURRENTLY ALONG A LINE FROM
DFW TO GKY TO JUST SOUTH OF ACT...WITH DENSE FOG AND VLIFR
CONDITIONS OCCURRING ON THE WEST/COOL SIDE. CONDITIONS ON THE WARM
SIDE ARE MVFR/VFR. RUC KEEPS FRONT/COLD AIR WEDGED INTO THE REGION
THROUGH 3Z WITH RAPID MOVEMENT TO THE NORTHWEST OCCURRING SHORTLY
THEREAFTER AS UPPER SYSTEM APPROACHES FROM THE WEST. WILL KEEP
AFW/FTW/ACT AT VLIFR/LIFR THROUGH MID EVENING AND THEN SHOW QUICKLY
IMPROVING CONDITIONS TO MVFR AFTER 3Z OR SO. IT IS POSSIBLE
CIGS/VSBY WILL LIFT TO VFR BEHIND THE WARM FRONT AROUND MIDNIGHT
WITH SOUTHEAST WINDS INCREASING TO 10-15KT. ANY VFR PERIOD SHOULD
NOT LAST MORE THAN A FEW HOURS AND DO EXPECT NOCTURNAL STRATUS TO
MOVE BACK INTO THE AREA FROM THE SOUTHEAST LATER TONIGHT. MVFR
STRATUS LIKELY TO PERSIST INTO THE MORNING AND AFTERNOON HOURS.
FOR PRECIP WILL NOT MENTION ANY IN THE TAF AS ANY SHOWERS SHOULD
BE SPOTTY AND LIGHT THROUGH SATURDAY AFTERNOON. THEREAFTER SOME
MORE SIGNIFICANT RAIN IS POSSIBLE AS FRONT ARRIVES FROM THE WEST
SATURDAY EVENING.
TR.92
&&
.PREV UPDATE...
.UPDATE...
VISIBILITIES CONTINUE TO DROP ALONG THE FRONTAL BOUNDARY WHICH IS
LOCATED NEAR THE INTERSTATE 35 CORRIDOR AND A DENSE FOG ADVISORY
IS NEEDED. CONDITIONS SHOULD IMPROVE FROM EAST TO WEST AS THE WARM
FRONT LIFTS AND WILL ONLY HAVE THE ADVISORY IN EFFECT UNTIL
MIDNIGHT.
85/NH
&&
.PREV DISCUSSION... /ISSUED 334 PM CST FRI DEC 2 2011/
SEVERAL FORECAST CHALLENGES EXIST THIS WEEKEND AND INTO EARLY NEXT
WEEK. THE EARLY CHALLENGES ARE TIMING OF DISTURBANCES EXITING
VIGOROUS UPPER LOW OVER THE SOUTHERN GREAT BASIN AND BAJA MEXICO
AND ASSOCIATED RAIN CHANCES. AS EXPECTED...BEST ISENTROPIC ASCENT
IS SHIFTING ACROSS WESTERN NORTH TEXAS WITH THE FRONT CONTINUING TO
SLOWLY MOVE WEST ACROSS THE I-35 CORRIDOR AND DFW METRO. AREAS OF
FOG WILL CONTINUE ALONG AND WEST OF THE FRONT AS IT RETROGRADES
SLOWLY THROUGH WESTERN NORTH TEXAS. INCREASING ISENTROPIC ASCENT
ALREADY BEING SEEN ON REGIONAL RADARS AHEAD OF NEXT SHORTWAVE
EJECTING OUT OF NORTHERN MEXICO AND WILL CONTINUE HIGHEST RAIN
CHANCES ACROSS THE WESTERN THIRD OF NORTH TEXAS. AS THE FRONT
SHIFTS WEST...TEMPERATURES OVERNIGHT WILL WARM SLOWLY OR REMAIN
STEADY AS CLOUDS AND ISENTROPIC LIFT KEEP CLOUDS/PATCHY LIGHT RAIN
AND SOME FOG AROUND...BUT FOG SHOULD NOT BE AS THICK AS IT WILL BE
IN THE COLDER AIR TO THE WEST.
BEST LIGHT RAIN CHANCES WILL REMAIN ACROSS FAR WESTERN NORTH TEXAS
OVERNIGHT AND SATURDAY MORNING WITH THE FRONT NEARBY AND BEST
ISENTROPIC LIFT FROM THE SHORTWAVE DISTURBANCE MOVING THROUGH.
MID LEVEL LAPSE RATES WILL INCREASE BY SATURDAY AFTERNOON AHEAD OF
A SECOND...STRONGER COLD FRONT HEADING SOUTHEAST TOWARD NORTH
TEXAS. HAVE INSERTED A MENTION OF ISOLATED THUNDERSTORMS THROUGH
SATURDAY NIGHT...THEN SUNDAY MORNING SOUTH AS THE STRONG COLD
FRONT SURGES THROUGH THE REGION. THE COMBINATION OF FORCING FROM
BOTH THE COLD FRONT AND YET ANOTHER SHORTWAVE DISTURBANCE WILL
RESULT IN LIKELY RAIN CHANCES FOR ALL SATURDAY NIGHT...WITH BEST
CHANCES ALONG THE FRONT AND ACROSS CENTRAL/EAST TEXAS ON SUNDAY
WITH BLUSTERY NORTH WINDS. A CHILLY AND RAW DAY IS EXPECTED SUNDAY
WITH LOCALIZED HEAVIER RAIN AMOUNTS IN EXCESS OF AN INCH POSSIBLE.
THE COLD AIR WILL DEEPEN SUNDAY NIGHT AS THE COLD FRONT SURGES OFF
THE TEXAS COAST AND INTO THE GULF OF MEXICO. UPPER LEVEL ENERGY
WILL CONTINUE TO PUSH ACROSS THROUGH MONDAY WITH CONTINUING COLD
AND BRISK CONDITIONS THROUGH MONDAY. THIS IS WHERE THE UNCERTAINTY
INCREASES REGARDING ANY TRANSITION TO WINTRY PRECIP. THE INITIAL THREAT
WILL OCCUR ACROSS THE NORTHWEST COUNTIES BY MONDAY MORNING...THEN
FOR THE REMAINDER OF NORTH TEXAS LATER MONDAY AFTERNOON INTO
MONDAY NIGHT. MODELS ARE DIFFERING ON THE TIMING AND SOUTHEAST
EXTENT OF THE COLD AIRMASS. ANALYSIS OF THE COLUMN ON FORECAST
SOUNDINGS INDICATE THE NAM BEING MORE SHALLOW...WHILE THE
GFS/CANADIAN ARE MORE ROBUST OF BRINGING IN THE DEEPER COLD AIR
AND TRANSITION IN MORE QUICKLY. WITH CONFIDENCE WAVERING THIS FAR
OUT...HAVE TAKEN A BLEND AND GONE WITH A VARYING MIXTURE OF
RAIN...FREEZING RAIN... AND SLEET ACROSS THE NORTHWEST HALF OF
NORTH TEXAS MONDAY MORNING. AS THE COLD AIR DEEPENS LATE MONDAY
INTO MONDAY NIGHT...WILL TRANSITION TO MORE OF A SNOW/SLEET MIX
FOR THE NORTHWEST HALF INCLUDING THE DFW METRO. FOR THE SOUTHEAST
HALF OF NORTH TEXAS ALONG AND SOUTH OF A WACO TO PARIS LINE...HAVE
DELAYED INSERTING CHANCES FOR WINTER PRECIPITATION UNTIL MONDAY
NIGHT DUE TO AFOREMENTIONED UNCERTAINTIES WITH THE UPPER ENERGY
LIFTING ACROSS.
FORECASTS WILL BE FINE TUNED THROUGH THE WEEKEND AS MODELS
HOPEFULLY COME INTO BETTER AGREEMENT ON THE DEPTH OF COLD AIR AND
TIMING ACROSS THE AREA ON MONDAY. NO WINTER WEATHER OUTLOOK
ISSUED AT THIS TIME...HOWEVER A WINTER WEATHER OUTLOOK OR ADVISORIES
COULD BE ISSUED IN THE NEXT DAY OR SO IF AGREEMENT IS ACHIEVED AND
CHANCES INCREASE TO A HIGHER CATEGORY.
THE UPPER LOW WILL FINALLY OPEN AND LIFT AWAY FROM NORTH TEXAS BY
TUESDAY MORNING...LEAVING A DEEP DRY AND COLD AIRMASS IN ITS WAKE
THROUGH MID WEEK. A SLOW WARM UP IS EXPECTED LATE WEEK...BUT HAVE
SLOWED DOWN TRENDS AND HAVE LOWERED HIGH TEMPERATURES CONSIDERING
THE SHEAR DEPTH OF THE COLD AIR DOME NOTED ON MODEL SOUNDINGS.
05/
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 48 68 41 44 36 / 30 50 70 70 60
WACO, TX 51 69 43 46 35 / 20 30 80 70 70
PARIS, TX 47 64 42 46 38 / 20 30 80 80 60
DENTON, TX 45 65 35 42 31 / 40 60 70 70 60
MCKINNEY, TX 44 65 38 44 34 / 30 40 80 70 60
DALLAS, TX 49 68 42 45 37 / 30 40 70 70 60
TERRELL, TX 48 67 43 45 38 / 20 30 70 80 60
CORSICANA, TX 48 69 47 48 40 / 20 20 80 80 70
TEMPLE, TX 52 70 42 48 35 / 30 30 80 70 70
MINERAL WELLS, TX 43 65 35 41 30 / 60 70 60 60 60
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR TXZ091-100>102-
115>117-129>132-141>144-156-157.
&&
$$
85/85
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
545 PM CST FRI DEC 2 2011
.AVIATION...
WARM FRONT SLOWLY MOVING NORTHWEST IS CURRENTLY ALONG A LINE FROM
DFW TO GKY TO JUST SOUTH OF ACT...WITH DENSE FOG AND VLIFR
CONDITIONS OCCURRING ON THE WEST/COOL SIDE. CONDITIONS ON THE WARM
SIDE ARE MVFR/VFR. RUC KEEPS FRONT/COLD AIR WEDGED INTO THE REGION
THROUGH 3Z WITH RAPID MOVEMENT TO THE NORTHWEST OCCURRING SHORTLY
THEREAFTER AS UPPER SYSTEM APPROACHES FROM THE WEST. WILL KEEP
AFW/FTW/ACT AT VLIFR/LIFR THROUGH MID EVENING AND THEN SHOW QUICKLY
IMPROVING CONDITIONS TO MVFR AFTER 3Z OR SO. IT IS POSSIBLE
CIGS/VSBY WILL LIFT TO VFR BEHIND THE WARM FRONT AROUND MIDNIGHT
WITH SOUTHEAST WINDS INCREASING TO 10-15KT. ANY VFR PERIOD SHOULD
NOT LAST MORE THAN A FEW HOURS AND DO EXPECT NOCTURNAL STRATUS TO
MOVE BACK INTO THE AREA FROM THE SOUTHEAST LATER TONIGHT. MVFR
STRATUS LIKELY TO PERSIST INTO THE MORNING AND AFTERNOON HOURS.
FOR PRECIP WILL NOT MENTION ANY IN THE TAF AS ANY SHOWERS SHOULD
BE SPOTTY AND LIGHT THROUGH SATURDAY AFTERNOON. THEREAFTER SOME
MORE SIGNIFICANT RAIN IS POSSIBLE AS FRONT ARRIVES FROM THE WEST
SATURDAY EVENING.
TR.92
&&
.UPDATE...
VISIBILITIES CONTINUE TO DROP ALONG THE FRONTAL BOUNDARY WHICH IS
LOCATED NEAR THE INTERSTATE 35 CORRIDOR AND A DENSE FOG ADVISORY
IS NEEDED. CONDITIONS SHOULD IMPROVE FROM EAST TO WEST AS THE WARM
FRONT LIFTS AND WILL ONLY HAVE THE ADVISORY IN EFFECT UNTIL
MIDNIGHT.
85/NH
&&
.PREV DISCUSSION... /ISSUED 334 PM CST FRI DEC 2 2011/
SEVERAL FORECAST CHALLENGES EXIST THIS WEEKEND AND INTO EARLY NEXT
WEEK. THE EARLY CHALLENGES ARE TIMING OF DISTURBANCES EXITING
VIGOROUS UPPER LOW OVER THE SOUTHERN GREAT BASIN AND BAJA MEXICO
AND ASSOCIATED RAIN CHANCES. AS EXPECTED...BEST ISENTROPIC ASCENT
IS SHIFTING ACROSS WESTERN NORTH TEXAS WITH THE FRONT CONTINUING TO
SLOWLY MOVE WEST ACROSS THE I-35 CORRIDOR AND DFW METRO. AREAS OF
FOG WILL CONTINUE ALONG AND WEST OF THE FRONT AS IT RETROGRADES
SLOWLY THROUGH WESTERN NORTH TEXAS. INCREASING ISENTROPIC ASCENT
ALREADY BEING SEEN ON REGIONAL RADARS AHEAD OF NEXT SHORTWAVE
EJECTING OUT OF NORTHERN MEXICO AND WILL CONTINUE HIGHEST RAIN
CHANCES ACROSS THE WESTERN THIRD OF NORTH TEXAS. AS THE FRONT
SHIFTS WEST...TEMPERATURES OVERNIGHT WILL WARM SLOWLY OR REMAIN
STEADY AS CLOUDS AND ISENTROPIC LIFT KEEP CLOUDS/PATCHY LIGHT RAIN
AND SOME FOG AROUND...BUT FOG SHOULD NOT BE AS THICK AS IT WILL BE
IN THE COLDER AIR TO THE WEST.
BEST LIGHT RAIN CHANCES WILL REMAIN ACROSS FAR WESTERN NORTH TEXAS
OVERNIGHT AND SATURDAY MORNING WITH THE FRONT NEARBY AND BEST
ISENTROPIC LIFT FROM THE SHORTWAVE DISTURBANCE MOVING THROUGH.
MID LEVEL LAPSE RATES WILL INCREASE BY SATURDAY AFTERNOON AHEAD OF
A SECOND...STRONGER COLD FRONT HEADING SOUTHEAST TOWARD NORTH
TEXAS. HAVE INSERTED A MENTION OF ISOLATED THUNDERSTORMS THROUGH
SATURDAY NIGHT...THEN SUNDAY MORNING SOUTH AS THE STRONG COLD
FRONT SURGES THROUGH THE REGION. THE COMBINATION OF FORCING FROM
BOTH THE COLD FRONT AND YET ANOTHER SHORTWAVE DISTURBANCE WILL
RESULT IN LIKELY RAIN CHANCES FOR ALL SATURDAY NIGHT...WITH BEST
CHANCES ALONG THE FRONT AND ACROSS CENTRAL/EAST TEXAS ON SUNDAY
WITH BLUSTERY NORTH WINDS. A CHILLY AND RAW DAY IS EXPECTED SUNDAY
WITH LOCALIZED HEAVIER RAIN AMOUNTS IN EXCESS OF AN INCH POSSIBLE.
THE COLD AIR WILL DEEPEN SUNDAY NIGHT AS THE COLD FRONT SURGES OFF
THE TEXAS COAST AND INTO THE GULF OF MEXICO. UPPER LEVEL ENERGY
WILL CONTINUE TO PUSH ACROSS THROUGH MONDAY WITH CONTINUING COLD
AND BRISK CONDITIONS THROUGH MONDAY. THIS IS WHERE THE UNCERTAINTY
INCREASES REGARDING ANY TRANSITION TO WINTRY PRECIP. THE INITIAL THREAT
WILL OCCUR ACROSS THE NORTHWEST COUNTIES BY MONDAY MORNING...THEN
FOR THE REMAINDER OF NORTH TEXAS LATER MONDAY AFTERNOON INTO
MONDAY NIGHT. MODELS ARE DIFFERING ON THE TIMING AND SOUTHEAST
EXTENT OF THE COLD AIRMASS. ANALYSIS OF THE COLUMN ON FORECAST
SOUNDINGS INDICATE THE NAM BEING MORE SHALLOW...WHILE THE
GFS/CANADIAN ARE MORE ROBUST OF BRINGING IN THE DEEPER COLD AIR
AND TRANSITION IN MORE QUICKLY. WITH CONFIDENCE WAVERING THIS FAR
OUT...HAVE TAKEN A BLEND AND GONE WITH A VARYING MIXTURE OF
RAIN...FREEZING RAIN... AND SLEET ACROSS THE NORTHWEST HALF OF
NORTH TEXAS MONDAY MORNING. AS THE COLD AIR DEEPENS LATE MONDAY
INTO MONDAY NIGHT...WILL TRANSITION TO MORE OF A SNOW/SLEET MIX
FOR THE NORTHWEST HALF INCLUDING THE DFW METRO. FOR THE SOUTHEAST
HALF OF NORTH TEXAS ALONG AND SOUTH OF A WACO TO PARIS LINE...HAVE
DELAYED INSERTING CHANCES FOR WINTER PRECIPITATION UNTIL MONDAY
NIGHT DUE TO AFOREMENTIONED UNCERTAINTIES WITH THE UPPER ENERGY
LIFTING ACROSS.
FORECASTS WILL BE FINE TUNED THROUGH THE WEEKEND AS MODELS
HOPEFULLY COME INTO BETTER AGREEMENT ON THE DEPTH OF COLD AIR AND
TIMING ACROSS THE AREA ON MONDAY. NO WINTER WEATHER OUTLOOK
ISSUED AT THIS TIME...HOWEVER A WINTER WEATHER OUTLOOK OR ADVISORIES
COULD BE ISSUED IN THE NEXT DAY OR SO IF AGREEMENT IS ACHIEVED AND
CHANCES INCREASE TO A HIGHER CATEGORY.
THE UPPER LOW WILL FINALLY OPEN AND LIFT AWAY FROM NORTH TEXAS BY
TUESDAY MORNING...LEAVING A DEEP DRY AND COLD AIRMASS IN ITS WAKE
THROUGH MID WEEK. A SLOW WARM UP IS EXPECTED LATE WEEK...BUT HAVE
SLOWED DOWN TRENDS AND HAVE LOWERED HIGH TEMPERATURES CONSIDERING
THE SHEAR DEPTH OF THE COLD AIR DOME NOTED ON MODEL SOUNDINGS.
05/
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 48 68 41 44 36 / 30 50 70 70 60
WACO, TX 52 69 43 46 35 / 20 30 80 70 70
PARIS, TX 42 64 42 46 38 / 20 30 80 80 60
DENTON, TX 45 65 35 42 31 / 40 60 70 70 60
MCKINNEY, TX 43 65 38 44 34 / 30 40 80 70 60
DALLAS, TX 49 68 42 45 37 / 30 40 70 70 60
TERRELL, TX 45 67 43 45 38 / 20 30 70 80 60
CORSICANA, TX 49 69 47 48 40 / 20 20 80 80 70
TEMPLE, TX 52 70 42 48 35 / 30 30 80 70 70
MINERAL WELLS, TX 45 65 35 41 30 / 60 70 60 60 60
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR TXZ091-092-
100>103-115>118-129>133-141>145-156>159.
&&
$$
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
1035 AM CST THU DEC 1 2011
.UPDATE...
LOW CLOUDS CONTINUE TO STREAM NORTHWARD WEST OF INTERSTATE 35
AHEAD OF OUR APPROACHING SYSTEM. THE COLD FRONT IS CURRENTLY
LOCATED AS FAR SOUTH AS CHILDRESS AND IS ORIENTED ALMOST STRAIGHT
NORTHWARD. WE SHOULD SEE MORE OF AN EASTWARD PROGRESSION THIS
AFTERNOON AS IT MOVES SLOWLY SOUTH. THE FRONT SHOULD STALL NEAR A
LINE FROM SHERMAN TO FORT WORTH TO COMANCHE AFTER DAYBREAK BEFORE
RETURNING TO THE NORTH AHEAD OF AN APPROACHING UPPER TROUGH.
ISENTROPIC LIFT IS FORECASTED TO BE STRONG AND DEEP BEHIND THE
FRONTAL BOUNDARY OVERNIGHT. MOISTURE AND INSTABILITY LOOK TO BE
BEST ACROSS THE NORTHWEST ZONES AND HAVE UPPED THE POPS TO LIKELY
FOR THESE LOCATIONS. SEVERAL OF THE SHORT-TERM MODELS AND THE GFS
SHOW ENOUGH LIFT ALONG THE BOUNDARY FOR SOME PRECIP AND HAVE
INCLUDED A 20 POP FOR POINTS FROM BONHAM SOUTHWESTWARD INTO THE
METROPLEX. WILL CONTINUE TO ASSESS HOW FAR EAST THE RAIN IS LIKELY
TO BE AND MAY NEED TO RAISE POPS FOR TONIGHT WITH THE AFTERNOON
PACKAGE.
85/NH
&&
.AVIATION...
15Z UPDATE/CONCERNS...
STRONG WARM ADVECTION ON 30KT+ WINDS IN THE 1.5-3 KFT LAYER IS
INDUCING RAPID MVFR STRATUS GROWTH ALONG/WEST OF I-35 CORRIDOR.
CIGS INITIALLY WILL BE EITHER OF 2 KFT. RUC SOUNDINGS SHOW THAT
WARMING TODAY WILL RESULT IN CIGS RAPIDLY RISING TO VFR UNDER 4
KFT BY 17Z...THEN QUICKLY RISING ABOVE 4 KFT BY 18Z AND AFTER.
OTHERWISE...COLD FRONT WILL REMAIN WELL NORTHWEST OF NORTH TX
TERMINALS TODAY. SOUTHEAST WINDS AROUND 10 MPH WILL BACK TO THE
EAST AT/BELOW 10 KTS BY 00Z FRIDAY.
05/
&&
.PREV DISCUSSION... /ISSUED 346 AM CST THU DEC 1 2011/
NO MAJOR CHANGES TO THIS PACKAGE. RAIN IS STILL EXPECTED TO BEGIN
IN WESTERN COUNTIES ON FRIDAY...WITH RAIN LIKELY OVER ALMOST ALL
OF NORTH TEXAS BEGINNING SATURDAY MORNING AND SPREADING EAST
THROUGH SUNDAY MORNING. PRECIP SHOULD SHUT OFF BY SUNDAY NIGHT IN
ALL BUT SOUTHEASTERN COUNTIES WHERE SOME OVER RUNNING PRECIP IS
INDICATED FOR MONDAY. HAVE REMOVED MENTION OF THUNDER IN SOUTHERN
COUNTIES DUE TO VERY MARGINAL CAPE VALUES. THERE MAY BE A
LIGHTNING STRIKE OR TWO SOMEWHERE IN THE SOUTH...BUT REAL
INSTABILITY APPEARS TO REMAIN SOUTH OF THE NORTH TEXAS CWA.
COLD FRONT REACHES NORTHWEST COUNTIES SATURDAY NIGHT AND PUSHES
SOUTHEAST OF SOUTHERN COUNTIES SUNDAY MORNING. AT THIS
TIME...TEMPERATURES APPEAR WARM ENOUGH THAT NO WINTER PRECIP IS
EXPECTED IN NORTH TEXAS. SHOULD THE COLD FRONT ARRIVE EARLIER AND
STRONGER...NORTHWEST COUNTIES MAY SEE SOME FREEZING RAIN SUNDAY
MORNING. WILL CONTINUE TO MONITOR MODEL TRENDS ON
TEMPERATURES/FROPA TIMING.
REST OF THE WEEK LOOKS COOL AND DRY. WITH LIGHT WINDS...CLEAR
SKIES...AND COOL DRY AIR MASS...WEDNESDAY MORNING LIKELY TO BE
BELOW FREEZING OVER THE ENTIRE NORTH TEXAS AREA. ECMWF/GFS PROG
MOISTURE RETURN ON DAY 8 FRIDAY...BEYOND SCOPE OF THIS FORECAST.
84
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 64 50 60 54 65 / 5 20 40 40 70
WACO, TX 67 53 64 56 68 / 5 10 40 40 60
PARIS, TX 62 45 59 46 62 / 5 10 20 30 70
DENTON, TX 63 46 57 54 64 / 5 20 40 50 70
MCKINNEY, TX 63 46 58 51 64 / 5 20 30 40 70
DALLAS, TX 64 51 61 53 65 / 5 20 30 40 70
TERRELL, TX 64 47 61 51 64 / 5 10 30 30 60
CORSICANA, TX 67 50 66 54 68 / 5 10 30 30 60
TEMPLE, TX 67 53 64 56 68 / 5 10 40 50 60
MINERAL WELLS, TX 63 46 56 56 63 / 10 50 50 60 70
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
85/85
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
916 AM CST THU DEC 1 2011
.AVIATION...
15Z UPDATE/CONCERNS...
STRONG WARM ADVECTION ON 30KT+ WINDS IN THE 1.5-3 KFT LAYER IS
INDUCING RAPID MVFR STRATUS GROWTH ALONG/WEST OF I-35 CORRIDOR.
CIGS INITIALLY WILL BE EITHER OF 2 KFT. RUC SOUNDINGS SHOW THAT
WARMING TODAY WILL RESULT IN CIGS RAPIDLY RISING TO VFR UNDER 4
KFT BY 17Z...THEN QUICKLY RISING ABOVE 4 KFT BY 18Z AND AFTER.
OTHERWISE...COLD FRONT WILL REMAIN WELL NORTHWEST OF NORTH TX
TERMINALS TODAY. SOUTHEAST WINDS AROUND 10 MPH WILL BACK TO THE
EAST AT/BELOW 10 KTS BY 00Z FRIDAY.
05/
&&
.PREV DISCUSSION... /ISSUED 346 AM CST THU DEC 1 2011/
NO MAJOR CHANGES TO THIS PACKAGE. RAIN IS STILL EXPECTED TO BEGIN
IN WESTERN COUNTIES ON FRIDAY...WITH RAIN LIKELY OVER ALMOST ALL
OF NORTH TEXAS BEGINNING SATURDAY MORNING AND SPREADING EAST
THROUGH SUNDAY MORNING. PRECIP SHOULD SHUT OFF BY SUNDAY NIGHT IN
ALL BUT SOUTHEASTERN COUNTIES WHERE SOME OVER RUNNING PRECIP IS
INDICATED FOR MONDAY. HAVE REMOVED MENTION OF THUNDER IN SOUTHERN
COUNTIES DUE TO VERY MARGINAL CAPE VALUES. THERE MAY BE A
LIGHTNING STRIKE OR TWO SOMEWHERE IN THE SOUTH...BUT REAL
INSTABILITY APPEARS TO REMAIN SOUTH OF THE NORTH TEXAS CWA.
COLD FRONT REACHES NORTHWEST COUNTIES SATURDAY NIGHT AND PUSHES
SOUTHEAST OF SOUTHERN COUNTIES SUNDAY MORNING. AT THIS
TIME...TEMPERATURES APPEAR WARM ENOUGH THAT NO WINTER PRECIP IS
EXPECTED IN NORTH TEXAS. SHOULD THE COLD FRONT ARRIVE EARLIER AND
STRONGER...NORTHWEST COUNTIES MAY SEE SOME FREEZING RAIN SUNDAY
MORNING. WILL CONTINUE TO MONITOR MODEL TRENDS ON
TEMPERATURES/FROPA TIMING.
REST OF THE WEEK LOOKS COOL AND DRY. WITH LIGHT WINDS...CLEAR
SKIES...AND COOL DRY AIR MASS...WEDNESDAY MORNING LIKELY TO BE
BELOW FREEZING OVER THE ENTIRE NORTH TEXAS AREA. ECMWF/GFS PROG
MOISTURE RETURN ON DAY 8 FRIDAY...BEYOND SCOPE OF THIS FORECAST.
84
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 64 50 60 54 65 / 5 10 40 40 70
WACO, TX 67 53 64 56 68 / 5 10 40 40 60
PARIS, TX 62 45 59 46 62 / 5 10 20 30 70
DENTON, TX 63 46 57 54 64 / 5 10 40 50 70
MCKINNEY, TX 63 46 58 51 64 / 5 10 30 40 70
DALLAS, TX 64 51 61 53 65 / 5 10 30 40 70
TERRELL, TX 64 47 61 51 64 / 5 10 30 30 60
CORSICANA, TX 67 50 66 54 68 / 5 10 30 30 60
TEMPLE, TX 67 53 64 56 68 / 5 10 40 50 60
MINERAL WELLS, TX 61 46 56 56 63 / 10 40 50 60 70
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
05/84
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1038 PM MST WED NOV 30 2011
.AVIATION...06Z TAFS
SNOW HAS BECOME MORE WIDESPREAD THE PAST FEW RADAR IMAGES ACROSS
SOUTHERN WYOMING. STRONG THREE HOUR PRESSURE TENDENCIES OBSERVED
OVER NORTHERN AND NORTHWESTERN WYOMING AT 03Z STILL AN INDICATION
THAT STRONG WINDS ARE GOING TO MATERIALIZE. MEDICINE BOW PROFILER
HAS SHOWN AN INCREASE IN NORTHEASTERLY WINDS TO 25KTS AT 05Z.
FLIGHT CONDITIONS HAVE GONE DOWN IN AREAS WHERE SNOW HAS
DEVELOPED. WITH THE SNOW AREA CONTINUING TO EXPAND...DO EXPECT
IFR/LIFR CONDITIONS TO CONTINUE. THE EXCEPTION MAY BE LARAMIE
WHERE WINDS ARE BECOMING MORE DOWNSLOPING OFF THE WESTERN LARAMIE
SLOPES. WILL NEED TO CONTINUE MONITORING. GENERALLY FOLLOWED
LATEST HRRR GUIDANCE ON TIMING OF LOWERING CONDITIONS OVERNIGHT.
CONDITIONS EXPECTED TO IMPROVE LATE MORNING INTO THE AFTERNOON HOURS.
CLAYCOMB
&&
.PREV DISCUSSION... /ISSUED 816 PM MST WED NOV 30 2011/
UPDATE...
WINTER STORM STILL APPEARS TO BE ON TRACK ACROSS MUCH OF SOUTHEAST
WYOMING AND THE WESTERN NEBRASKA PANHANDLE IN THE WAKE OF A STRONG
COLD FRONT MOVING RAPIDLY SOUTHEASTWARD ACROSS THE REGION. THIS
FRONT HAS ALREADY CLEARED OUR FORECAST AREA...WITH 3-HOUR PRESSURE
RISES RANGING FROM 3 TO 5 MILLIBARS OVERSPREADING A LARGE PORTION
OF CENTRAL AND EASTERN WYOMING. NORTH TO NORTHEAST WINDS HAVE
INCREASED TO BETWEEN 20 AND 30 MPH ACROSS MOST AREAS...WITH GUSTS
AS HIGH AS 35 MPH. THESE WINDS SHOULD PERSIST...AND PERHAPS
INCREASE OVERNIGHT AS H7-H75 WINDS INCREASE TO BETWEEN 35 AND 40
KTS...ESPECIALLY OVER OUR MOUNTAIN ZONES.
RECENT TRENDS IN RADAR AND INFRARED SATELLITE IMAGERY/COOLING
CLOUD TOPS INDICATE SNOW IS BEGINNING TO INCREASE IN COVERAGE AND
INTENSITY ACROSS MUCH OF SOUTHEAST WYOMING. THE INHERITED WINTER
STORM WARNING LOOKS GOOD WITH THE POTENTIAL FOR SIGNIFICANT
BLOWING AND DRIFTING SNOW DESPITE SNOW AMOUNTS LIKELY STRUGGLING
TO REACH WARNING CRITERIA. HIGH SNOW RATIOS IN EXCESS OF 15 TO 1
ARE ALSO LIKELY AS H7 TEMPERATURES PLUNGE TO BETWEEN -10C AND
-15C...SO FRESH SNOW SHOULD BE EASY TO BLOW AROUND. THE LATEST
CONCERN IS THE NORTHERN LARAMIE RANGE...WITH NORTH-FACING SLOPES
BEING ESPECIALLY PRONE TO UPSLOPE ENHANCEMENT LATER TONIGHT. THIS
AREA IS BEING HIT HARD BY THE NAM AND ECMWF...WHICH SEEMS QUITE
REALISTIC GIVEN THE LOW-LEVEL FLOW REGIME. WITH 5 TO 10 INCHES OF
SNOW AND WIND GUSTS IN EXCESS OF 40 MPH...WE HAVE OPTED TO ADD OUR
FAR NORTHWEST MOUNTAIN ZONES TO THE CURRENT WINTER STORM WARNING. THE
SNOW AND BLOWING SNOW ADVISORY HAS ALSO BEEN EXPANDED TO INCLUDE
THE REMAINDER OF THE WESTERN NEBRASKA PANHANDLE...AND CONVERSE AND
NIOBRARA COUNTIES IN EAST CENTRAL WYOMING. WIND WILL BE THE
BIGGEST CONCERN ACROSS THESE AREAS AS VERY STRONG PRESSURE RISES
OVERSPREAD THE REGION BY DAYBREAK THURSDAY. MODEST SNOW
ACCUMULATIONS AND WINDS IN EXCESS OF 30 MPH SHOULD BE MORE THAN
SUFFICIENT FOR HAZARDOUS TRAVEL.
&&
PREV DISCUSSION... /ISSUED 202 PM MST WED NOV 30 2011/
SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT.
TONIGHT...THE FINAL DAY OF NOVEMBER WILL GO OUT LIKE A LAMB WITH
HIGH TEMPERATURES IN THE 40S AND 50S...WITH THE FIRST DAY OF
DECEMBER COMING IN LIKE A LION AS A STRONG COLD FRONT QUICKLY ROARS
THROUGH OUR COUNTIES BY EARLY EVENING. 3 HOURLY PRESSURE RISES OF 2
TO 7 MB OCCURRING ACROSS NORTHERN MONTANA WILL KEEP THE FRONT
BARRELING SOUTH.
CURRENT WINTER STORM WARNING AND WINTER WEATHER ADVISORY AREAS AND
TIMING LOOK GOOD BASED ON EXPECTED SNOWFALL AMOUNTS...AND ESPECIALLY
WITH THE COMBINATION OF BLOWING SNOW...REDUCED VISIBILITIES AND COLD
TEMPERATURES.
WIDESPREAD SNOW WILL DEVELOP THIS EVENING ACROSS SOUTHEAST WYOMING
AND SPREAD ACROSS WESTERN NEBRASKA LATE TONIGHT...LAGGING THE COLD
FRONT BY A FEW HOURS. STRONG SURFACE THROUGH 700 MB GRADIENTS WILL
PRODUCE BRISK NORTH WINDS DUE TO STRONG THICKNESS PACKING.
COMBINATION OF FALLING SNOW AND WINDS WILL PRODUCE AREAS OF BLOWING
SNOW AND VISIBILITIES NEAR ZERO.
THURSDAY...WIDESPREAD SNOW AND BLOWING SNOW CONTINUE IN THE MORNING
SOUTH OF A RAWLINS TO SCOTTSBLUFF LINE WITH SNOW TAPERING OFF TO THE
NORTH. IN THE AFTERNOON...SNOW WILL END IN THE NORTH WITH SNOW
DECREASING IN AREAL COVERAGE AND INTENSITY ACROSS OUR SOUTHERN
COUNTIES. MUCH COLDER WITH HIGHS IN THE TEENS AND 20S.
TOTAL MOUNTAIN SNOWFALL AMOUNTS WILL RANGE FROM 10 TO 14 INCHES...
WITH 4 TO 7 INCHES WEST OF A DOUGLAS TO CHEYENNE LINE AND 1 TO 4
INCHES ELSEWHERE.
THURSDAY NIGHT...VERY COLD WITH CLOUDS DECREASING AND FRESH SNOW
COVER. LOWS IN THE SINGLE DIGITS ABOVE AND BELOW ZERO.
FRIDAY...SLIGHT WARMING TREND IN ADVANCE OF THE NEXT REINFORCING
SHOT OF COLD AIR...THOUGH LIMITED BY RESIDUAL SNOW COVER.
FRIDAY NIGHT...NEXT SHORTWAVE TROUGH ALOFT AND COLD FRONT WILL BRING
SNOW AGAIN SOUTH OF A DOUGLAS TO SIDNEY LINE...THOUGH SNOWFALL
AMOUNTS WILL BE MORE LIMITED WITH LESS MOISTURE AVAILABILITY AND
LESS LIFT.
LONG TERM...SATURDAY THROUGH WEDNESDAY...THE 12Z MEDIUM RANGE MODELS
ALL DEPICT A HIGHLY AMPLIFIED UPPER LEVEL PATTERN ACROSS THE LOWER
48. A POSITIVELY-TILTED MEAN TROUGH WILL EXTEND FROM HUDSON BAY IN
CANADA TO THE FOUR CORNERS REGION...WITH A MEAN UPPER RIDGE OVER
THE NORTHEASTERN PACIFIC. A SERIES OF SHORT WAVES WILL TOP THE RIDGE
AND DROP SOUTH/SOUTHEAST THROUGH CENTRAL AND SOUTHERN CANADA INTO
THE NORTH CENTRAL STATES DURING THE PERIOD...REINFORCING THE MEAN
TROUGH. THIS PATTERN WILL MAINTAIN BELOW NORMAL TEMPERATURES WITH
A FEW CANADIAN COLD FRONTAL PASSAGES. THE UPPER LEVEL SYSTEM
RESPONSIBLE FOR THE LIGHT SNOW ON SATURDAY WILL MOVE EAST INTO
THE PLAINS SATURDAY NIGHT. IT WILL BE COLDER ON SATURDAY IN THE
WAKE OF A COLD FRONT WITH BRISK NORTHERLY WINDS. SATURDAY NIGHT
WILL BE COLD BUT DRY. THE NEXT COLD FRONT AND UPPER LEVEL
DISTURBANCE DROPS QUICKLY SOUTH THROUGH THE HIGH PLAINS SUNDAY AND
SUNDAY NIGHT WITH CHANCES FOR LIGHT SNOW MAINLY ALONG AND WEST OF
THE LARAMIE RANGE. POST-FRONTAL AIRMASS IS MODIFIED SO TEMPERATURES
WILL NOT BE AS CHILLY AS THE PREVIOUS SYSTEM. THE UPPER FLOW
BACKS FROM NORTHERLY TO WESTERLY ON TUESDAY IN ADVANCE OF THE
NEXT POTENT SHORT WAVE ENTERING THE NORTHWEST TIER OF THE NATION.
DOWNSLOPING EAST OF THE LARAMIE RANGE WILL RESULT IN WARMER...MORE
SEASONAL TEMPERATURES. THE NEXT COLD FRONT MOVES SOUTHEAST ACROSS
CENTRAL AND EASTERN WYOMING WEDNESDAY WITH CHANCES FOR RAIN/SNOW
ALONG WITH COOLER TEMPERATURES FOR NORTHERN AND WESTERN PORTIONS
OF THE CWA.
FIRE WEATHER...NO FIRE WEATHER CONCERNS.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING UNTIL 3 PM THURSDAY FOR WYZ103-WYZ104-
WYZ105-WYZ109-WYZ110-WYZ111-WYZ112-WYZ113-WYZ114.
WINTER STORM WARNING UNTIL 3 PM THURSDAY FOR WYZ115-WYZ116-
WYZ117-WYZ118-WYZ119.
WINTER WEATHER ADVISORY UNTIL 3 PM THURSDAY FOR WYZ101-WYZ102-
WYZ106-WYZ107-WYZ108.
NE...WINTER WEATHER ADVISORY UNTIL 3 PM THURSDAY FOR NEZ002-NEZ003-
NEZ019-NEZ020-NEZ021-NEZ054-NEZ055-NEZ095-NEZ096.
&&
$$
SHORT TERM...RUBIN
LONG TERM/AVIATION...JAMSKI
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
923 PM MST FRI DEC 2 2011
.UPDATE...COMPLEX WEATHER PATTERN EVOLVING ACROSS THE REGION AS
THE NRN ROCKIES TROUGH FORCES THE COLD FRONT TO REACH SOUTHWEST
COLORADO SATURDAY MORNING. THE STRONG TROUGH OVER ARIZONA PIVOTS
NORTHEAST WITH THE STRONGEST DYNAMICAL LIFT OVER WRN COLORADO AT
12Z (5 AM) SATURDAY. THE STRONGEST LIFT IN THE UPPER ATMOSPHERE
COINCIDES WITH THE SURFACE FRONT FROM THE NORTH...AND EXPECT THIS
TIME PERIOD TO BRING THE BEST SNOWFALL RATES TO THE FORECAST AREA.
MOISTURE IS SOMEWHAT LACKING BUT NOT NECESSARILY SPARSE WITH
700 MB SPECIFIC HUMIDITY BETWEEN 2.5 TO 3.0 G/KG. THIS IS GOOD
ENOUGH FOR SIGNIFICANT SNOW ACCUMULATIONS IF THE CRYSTAL GROWTH
TEMPERATURE REGION GETS SATURATED. THE EVENING SOUNDING SHOWS THE
HIGHEST HUMIDITY IN THIS LAYER. WITH UPWARDS MOTION INCREASING
DURING THE NIGHT...EXPECT THIS LAYER TO BECOME SATURATED. IN
ADDITION TO THE DYNAMICAL REASONING FOR THE ACCUMULATING
SNOWFALL...MODELS ALSO SHOW A WEAK TROWAL SIGNATURE THAT WILL ADD
TO THE SNOW POTENTIAL.
THE GFS/NAM DO NOT INDICATE SNOWFALL REACHING ADVISORY OR WARNING
CRITERIA FOR MUCH OF THE REGION (WITH THE EXCEPTION OF THE SWRN
SAN JUANS.) BUT THAT IS NOT NECESSARILY THE CASE WITH THE HIGHER
RESOLUTION MODELS SUCH AS THE 4KM WRF AND 3KM HRRR WHICH INDICATES
SIGNIFICANT ACCUMULATIONS FOCUSED OVER THE SAN JUAN
MOUNTAINS...GRAND MESA...AND POSSIBLY OVER THE SERN UTAH
MOUNTAINS. INCLUDED WINTER WEATHER ADVISORIES FOR THE GRAND AND
UNCOMPAHGRE VALLEY AS THIS APPEARS TO BE THE FIRST SNOW EVENT OF
THIS WINTER SEASON.
FOR NORTHEAST UTAH...NORTHEAST WINDS WILL INCREASE ONCE AGAIN AND
WILL BE A FACTOR (BUT NOT AS STRONG AS THE EVENT THAT OCCURRED
YESTERDAY MORNING.) A SPOTTER REPORT NORTH OF THE COLORADO BORDER
(12 MILES NORTH OF BAGGS) REPORTED SIGNIFICANT DRIFTING SNOW FROM
THE WIND. THIS WIND HAS NOT BEEN OBSERVED IN NW COLORADO BUT THE
TREND IS FOR GUSTY NORTHEAST WINDS AFTER MIDNIGHT. ISSUED WINTER
WEATHER ADVISORY ACROSS THIS REGION FOR THE ACCUMULATING SNOW AND
GUSTY WINDS THAT WILL ACCOMPANY THE FRONT.
&&
.AVIATION /FOR THE 06Z TAF ISSUANCE/...
DETERIORATING CONDITIONS WITH MVFR/IFR CONDITIONS BECOMING WIDESPREAD
AFTER 06Z THIS EVENING WITH CIGS BLO BKN010 AND VIS BLO 3SM -SN BR
FREQUENT AT ALL TAF SITES AND MANY AIRFIELDS. IMPROVEMENT AT THE
LOWER VALLEY TAF SITES (KGJT...KMTJ...KRIL AND KEGE) IS EXPECTED
AFTER 18Z SATURDAY AS CIGS IMPROVE AND SNOW DIMINISHES. MOUNTAIN
OBSCURATIONS WILL BE WIDESPREAD THROUGH SATURDAY.
&&
.PREV DISCUSSION... /ISSUED 308 AM MST FRI DEC 2 2011/
SHORT TERM /TONIGHT THROUGH SUNDAY/...
THE CLOSED LOW OVER AZ FINALLY BEGINNING TO OPEN UP AND IS EXPECTED
TO EJECT THROUGH NM AND THE 4 CORNERS TONIGHT AS THE NEXT TROUGH
DIVES DOWN TO REPLACE IT. MOISTURE HAS SPREAD ACROSS MUCH SE UT AND
WRN CO TODAY AND NICELY CAPTURED ON THE 300K POTENTIAL TEMP
SURFACE...WITH LIGHT SNOW REPORTED OVER HIGHER TERRAIN FROM MOUNT
WERNER ABOVE STEAMBOAT SPGS TO GRAND MESA TO THE SAN JUAN MTNS. SNOW
ALSO ALONG THE SRN BASE OF THE SAN JUANS FROM CORTEZ TO PAGOSA IN THE
UPSLOPE FLOW. RUC MODELS SHOWS A COUPLE WAVES OF ENERGY MOVING UP
FROM THE LOW...SO EXPECT SNOW INTENSITY TO VARY THROUGH THE NIGHT
IN SW CO. CURRENT WINTER HIGHLIGHTS FOR THE SAN JUAN/ABAJO/LA SAL
MTNS AND THE DURANGO-PAGOSA AREA LOOK ON TRACK.
THE SECOND SPLITTING TROUGH WAS DROPPING ACROSS ID AND DRIVEN BY A
120 KT UPPER JET OVER THE PAC NW. THIS TROUGH EXPECTED TO PUSH A COLD
FRONT INTO NE UT/NW CO TONIGHT AND THEN INTO SE UT/SW CO SAT AS IT
FORMS A SECOND CLOSED OVER AZ. RATHER NARROW BAND OF MOISTURE
ASSOCIATED WITH THE TROUGH MOVING INTO NW UT...BUT EXPECT SNOW
COVERAGE TO INCREASE OVER NE UT/NW CO TONIGHT AS THE FRONT
INTERACTS WITH THE MOISTURE IN PLACE AHEAD OF THE AZ LOW. THE FRONT
EXPECTED TO SLOW ACROSS THE N LATE TONIGHT...AND A PERIOD DECENT
NORTHEAST OROGRAPHIC WINDS COMBINED WITH COLD ADVECTION SHOULD BRING
3-6 INCHES OF SNOW TO THE ERN UINTA MTNS...ESPECIALLY THEIR NORTH
SLOPES. BUT...NORTHEAST WINDS NOT AS STRONG OR AS LONG IN DURATION
AS THE STORM WED NIGHT...SO REFRAINED FROM ANY HIGHLIGHT FOR THE ERN
UINTAS AT THIS TIME. A PERIOD OF GUSTY NE WINDS LIKELY ACROSS NW CO
SAT MORNING AS WELL...BUT AGAIN NOT NEARLY AS STRONG AS WHAT OCCURRED
THU MORNING.
BOTH NAM AND GFS INDICATE A WEAK 700 MB LOW FORMS OVER WRN CO
TONIGHT/SAT MORNING. BANKING ON ENHANCED LOW LEVEL CONVERGENCE
AND EVENTUAL FRONTAL PASSAGE TO ENHANCE SNOWFALL FROM GRAND MESA TO
THE WEST ELKS. WEST ELKS SHOULD ALSO BENEFIT FROM SOME MOIST
SOUTHERLY OROGRAPHIC FLOW TONIGHT...WHILE TRAILING NORTHERLY FLOW MAY
KEEP SOME LIGHT SNOW OVER GRAND MESA INTO SAT EVENING. AS SUCH...
ELECTED TO INCLUDE THE GRAND MESA AND WEST ELKS /ZONES 9 AND 12/ IN A
LOW-END ADVISORY TONIGHT INTO SAT EVENING FOR 4 TO 9 INCHES OF
SNOW. THE 700 MB LOW SHOULD ALSO BRING SNOW TO MANY CENTRAL VALLEYS
BUT WITH LITTLE ACCUMS EXPECTED.
SNOW DIMINISHES SAT NIGHT WITH CLEARING FROM THE NW. ERN UT/WRN CO
SHOULD BE IN BETWEEN SYSTEMS SUNDAY AS MODELS SHOW YET A THIRD
SPLITTING TROUGH APPROACHING FROM THE N LATE IN THE WEEKEND. WILL
TREND THE CHANCE OF PRECIP UP AGAIN ACROSS THE NORTHERN MTNS SUNDAY
AFTERNOON AS A RESULT.
LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
THE EARLY PART OF THE LONG TERM IS A CONTINUATION OF A REPEATING
PATTERN THAT HAS BEEN IN CONTROL SINCE THIS MIDWEEK. THE LAST OF A
SERIES OF SHORTWAVES WILL DROP SOUTHWARD INTO ARIZONA AND AGAIN FORM
A LOW TO OUR SOUTHWEST SUNDAY NIGHT INTO MONDAY. TODAY`S RUNS ARE
FARTHER WEST THAN YESTERDAY`S...WHICH DOES NOT ALLOW THE BEST
MOISTURE/DYNAMICS/OROGRAPHICS TO MOVE OVER OUR FORECAST AREA. THAT
SAID...THIS DISTURBANCE WILL BE IN CLOSE ENOUGH PROXIMITY FOR ANOTHER
ROUND OF MOUNTAIN SNOWFALL...WITH A CHANCE OF SNOW IN MANY VALLEYS.
THE FAVORED AREA WILL SWITCH FROM THE NORTH TO THE SOUTH LATE SUNDAY
NIGHT...WITH CLEARING OVER THE NORTH DURING THE DAY ON MONDAY. WINDS
DO NOT SEEM TO BE AS STRONG AS YESTERDAY`S SYSTEM...SO DO NOT
ANTICIPATE NEARLY AS MUCH BLOWING SNOW.
WE CONTINUE TO SEE SOME DISCREPANCIES IN RUN-TO-RUN AND BETWEEN-MODEL
SOLUTIONS FOR THE UPCOMING LONG TERM PERIOD. TODAY`S RUNS KEEP THE
AREA DRY THROUGH THE REMAINDER OF THE PERIOD. WE SIT UNDER A DRY AND
COLD NORTHWEST FLOW AS HIGH PRESSURE DOMINATES THE WEST COAST THROUGH
THE GREAT BASIN. THIS PATTERN IS NOW PROGGED TO PERSIST THROUGH THE
WORK WEEK. MODELS INDICATE THAT THERE MAY BE A COUPLE WEAK WAVES THAT
BRUSH THE NORTHERN EDGE...BUT THE TIMING AND TRACK IS BOUND TO CHANGE
WITH FUTURE MODEL RUNS.
TEMPERATURES WILL BE BELOW NORMAL IN THE DRY AIR MASS...ESPECIALLY AT
NIGHT. SOME MODIFICATION IS EXPECTED TOWARDS THE END OF THE PERIOD.
ANY WAVES THAT BRUSH THE AREA WILL ACT TO MODIFY TEMPS...AGAIN MAINLY
AT NIGHT.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...WINTER WEATHER ADVISORY UNTIL NOON MST SATURDAY FOR ZONES
001>003-006-011-013-020.
WINTER STORM WARNING UNTIL 11 PM MST SATURDAY FOR ZONES 009-018-
019.
WINTER WEATHER ADVISORY UNTIL 11 PM MST SATURDAY FOR ZONES 012-
017.
WINTER STORM WARNING UNTIL 3 PM MST SATURDAY FOR ZONES 021>023.
UT...WINTER WEATHER ADVISORY UNTIL NOON MST SATURDAY FOR ZONES 023-
025.
WINTER STORM WARNING UNTIL 11 PM MST SATURDAY FOR ZONE 028.
&&
$$
UPDATE.......PF
SHORT TERM...JAD
LONG TERM....EH
AVIATION.....PF
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
331 AM CST SAT DEC 3 2011
.SYNOPSIS...
06Z SFC ANALYSIS HAD A COLD FRONT FROM THE EASTERN DAKOTAS INTO
CENTRAL NEBRASKA. A LOW WAS IN EASTERN COLORADO WITH A FRONT INTO
SOUTHERN NEBRASKA. RADAR TRENDS SHOW A LARGE SHIELD OF WAA
ASSOCIATED WITH A WAVE FROM WISCONSIN BACK INTO WESTERN MISSOURI.
DEW POINTS WERE IN THE 30S AND 40S ACROSS MUCH OF THE MIDWEST WITH
20S OVER THE UPPER MIDWEST AND GREAT LAKES.
&&
.SHORT TERM...TODAY AND TONIGHT...
WAA HAS ALLOWED TEMPERATURES TO RISE AND PUSH WBZ SFC TEMPERATURES
TO ABOVE 34 FOR AREAS SOUTH OF HWY 20. ANY THREAT FOR FZRA OR FZDZ
WILL END BY SUNRISE AS WBZ TEMPERATURES CONTINUE TO RISE.
THE INITIAL WAA PRECIP SHIELD WILL MOVE ACROSS THE AREA DURING THE
MORNING HOURS. BASED ON RADAR AND RUC TRENDS THE OVERALL INTENSITY
OF THE PRECIP SHOULD DECREASE DURING THE MID TO LATE MORNING HOURS.
THE QUESTION THEN TURNS TO PRECIP CHANCES FOR THE AFTERNOON.
ALL MODELS SHOW CONDENSATION PRESSURE DEFICITS INCREASING DURING THE
AFTERNOON HOURS. FORCING WEAKENS AND CONVERGENCE IN THE LOWER LEVELS
EITHER WEAKENS OR IS NOT PRESENT. THUS PRECIP CHANCES WILL BE
GREATLY LOWER FOR MOST AREAS GENERALLY EAST OF A KEOK TO KFEP LINE
FOR MUCH OF THE AFTERNOON. THE POTENTIAL DOES EXIST THAT EASTERN
PARTS OF THE CWFA COULD GO COMPLETELY DRY DURING THE AFTERNOON
HOURS. THIS SCENARIO WILL HAVE TO BE RE-EVALUATED.
TONIGHT...THE MAIN SFC LOW ARRIVES AND BRINGS ANOTHER ROUND OF
PRECIPITATION TO THE AREA. WBZ TEMPERATURES ARE ABOVE 34 DEGREES SO
ALL PRECIPITATION WILL BE IN THE FORM OF RAIN DURING THE EVENING
HOURS. AFTER MIDNIGHT...THE RACE BEGINS WITH THE CAA TO SEE IF THE
PRECIP CAN MIX WITH AND CHANGE OVER TO SNOW PRIOR TO SUNRISE. THE
FAR NORTHWEST PART OF THE CWFA WOULD HAVE THE BEST CHANCE. MORE
INTERESTING IS THE DRY SLOT BEING DEPICTED BY THE MODELS. FORCING ON
THETA SURFACES 290-300K SHOW ALL FORCING ENDING VERY LATE TONIGHT
WHICH IS COINCIDENT WITH THE ARRIVAL OF THE DRY SLOT. THUS THE
POTENTIAL DOES EXIST THAT PRECIP MAY END PRIOR TO THE COLD AIR
ARRIVING. IF THIS WOULD OCCUR...THE POTENTIAL FOR A MIX OR A CHANGE
OVER IN THE NORTHWEST CWFA WOULD BE LOW.
IF THE PRECIPITATION DOES END...THE QUESTION THEN BECOMES WHETHER OR
NOT ANY FZDZ COULD DEVELOP. RIGHT NOW THE FCST SOUNDINGS DO NOT
SUGGEST THIS. THUS THE CURRENT THINKING IS THAT A MIX WILL DEVELOP
IN THE NORTHWEST WITH A QUICK CHANGE OVER BEFORE THE PRECIP ENDS.
AMOUNTS NOW LOOK TO BE UNDER AN INCH. ..08..
.LONG TERM...SUNDAY THROUGH FRIDAY...
SUNDAY IS THE TAIL END OF THE SHORT TERM STORM SYSTEM...WITH THE
LAST OF THE DEFORMATION ZONE PRECIPITATION EXITING OFF TO THE
NORTHEAST EARLY IN THE DAY. HAVE SOME SLIGHT CHANCE POPS FOR THE
MORNING HOURS WITH RAIN IN THE EAST...WITH MIXED RAIN SNOW ACROSS
THE NORTH.
ON MONDAY ANOTHER SHORTWAVE EJECTS OUT OF THE UPPER LEVEL TROUGH
AXIS AND MOVES NORTHEAST ALONG THE BAROCLINIC ZONE LEFT BEHIND THE
CURRENT STORM SYSTEM. THIS WAVE IS CURRENTLY FORECAST BY MOST OF
THE MODELS TO STAY SOUTHEAST OF THE FORECAST AREA...BUT THE NAM AND
THE 00Z ECMWF BRING IT FAR ENOUGH NORTH TO BRUSH OUR SOUTHEAST WITH
SOME LIGHT PRECIPITATION. HAVE DECIDED TO GO WITH THE DRIER
SOLUTION FOR NOW...BUT WILL HAVE TO RE-EVAULATE LATER AS NEEDED.
TUESDAY...WEDNESDAY AND EARLY THURSDAY APPEAR QUIET FOR NOW...WITH THE
LONGWAVE TROUGH SHIFTING EAST OF THE AREA AND WEAK RIDGING SETTLING
IN. TEMPERATURES WILL REMAIN COLD WITH HIGHS ONLY IN THE MID 20S TO
MID 30S.
THURSDAY NIGHT AND FRIDAY THE LONGWAVE TROUGH DEEPENS ACROSS THE
CONUS AGAIN AND WE HAVE A COLD FRONT DROP THROUGH THE AREA THURSDAY
NIGHT...FOLLOWED BY SOME SNOW. THIS IS A RELATIVELY NEW FEATURE IN
THE MODELS...BUT BOTH THE GFS AND ECMWF ARE SHOWING IT...SO HAVE
RAISED POPS SLIGHTLY ON THURSDAY NIGHT AND FRIDAY WITH SNOW
PRECIPITATION TYPE. TEMPERATURES STILL BELOW NORMAL WITH HIGHS IN
THE 20S AND LOWER 30S. ..LE..
&&
.AVIATION...
CIGS OF 2-3KFT AGL WILL CONTINUE TO LOWER THROUGH 18Z/03 WITH 1-2KFT
AGL COMMON WITH AREAS BLO 1KFT. GENERAL VSBYS OF 3-5SM ARE EXPECTED
WITH BRIEF PERIODS OF 1-2SM POSSIBLE. A LULL IN PRECIP IS EXPECTED
18Z/03-00Z/04 FOR KMLI/KBRL WHICH MAY RESULT IN CIGS/VSBYS BECOMING
VFR. KCID/KDBQ SHOULD REMAIN MVFR WITH 1-2KFT CIGS AND 3-5SM. AFT
00Z/04 CIGS FOR ALL SITES WILL LOWER TO ARND 1KFT WITH 3-5SM WITH
POTENTIAL FOR 1-2SM AND BLO 1KFT. KCID/KDBQ MAY SEE A RASN MIX OR
ALL SN AFT 08Z/04 BEFORE PRECIPITATION ENDS.
..08..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
08/LE
AREA FORECAST DISCUSSION
NWS GRAY ME
326 AM EST SAT DEC 3 2011
.SYNOPSIS...
HIGH PRESSURE WILL DOMINATE THE WEATHER PATTERN TODAY AND WILL
GRADUALLY SHIFT OFFSHORE BY TOMORROW. SOUTHWEST FLOW BRINGS WARMER
TEMPERATURES FOR SUNDAY AND MONDAY. A WEAK COLD FRONT MOVES INTO
NORTHERN PARTS OF THE AREA ON MONDAY BEFORE STALLING. LOW PRESSURE
TRACKS ALONG THE FRONT ON TUESDAY SPREADING RAIN ACROSS THE
REGION. A COLD FRONT WILL PUSH THROUGH THE AREA ON WEDNESDAY
BRINGING COLDER TEMPERATURES BACK TO THE AREA WITH RAIN CHANGING
TO SNOW BEFORE ENDING.
&&
.NEAR TERM /THROUGH TODAY/...
STRATUS DECK ASSOCIATED WITH SUBSIDENCE INVERSION HAS BEGUN TO
DIMINISH SLIGHTLY AS LOW LEVEL MOISTURE DECREASES. RUC FORECAST
SOUNDINGS CAPTURE THIS WELL AND SHOW MOISTURE SCATTERING OUT IN THE
NEXT FEW HOURS. CLOUDS WILL LIKELY REMAIN THROUGH DAYBREAK ACROSS
NORTHERN NH AND NORTH CENTRAL MAINE WITH SOME FOG MIXED IN.
ONCE CLOUDS DISAPPEAR TEMPERATURES WILL WARM QUICKLY IN THE DRY
ENVIRONMENT. READINGS WILL TOP OUT NEAR NORMAL VALUES WITH MID TO
UPPER 30S NORTH TO LOWER TO MID 40S SOUTH. IT SHOULD BE A PLEASANT
DAY WITH SUNNY SKIES AND LIGHT WINDS AS HIGH PRESSURE SLOWLY MOVES
OVER THE REGION.
&&
.SHORT TERM /TONIGHT THROUGH 6 PM SUNDAY/...
SURFACE HIGH PRESSURE WILL SHIFT OFFSHORE TONIGHT AS UPPER LEVEL
RIDGING BEGINS TO BREAK DOWN. SOUTHERLY FLOW WILL RESULT IN SLIGHTLY
HIGHER TEMPERATURES THAN SATURDAY WITH HIGHS IN THE LOWER 40S NORTH
TO LOWER 50S SOUTH. HIGH CLOUDS WILL BEGIN TO STREAM IN DURING THE
DAY AS THE UPPER LEVEL JET AND MAIN STORM TRACK NEAR...BUT MOST OF
THE DAY SHOULD BE SUNNY TO PARTLY CLOUDY. PRECIPITATION CHANCES WILL
HOLD OFF AS A FRONTAL BOUNDARY STALLS WELL TO OUR NORTHWEST.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
BROAD... PERSISTENT TROUGH STRETCHING FROM HUDSON BAY TO THE
SOUTHWEST DESERTS WILL BE THE DRIVING FORCE FOR WEATHER FEATURES
ACROSS THE CONTINENT THROUGH NEXT WEEK.
MINOR SHORTWAVE TROUGH CROSSES THROUGH QUEBEC ON SUNDAY NIGHT...
WITH A WEAK SURFACE LOW AND COLD FRONT ACCOMPANYING IT. THIS FRONT
MAY MAKE IT DOWN INTO THE NORTHERN PART OF MAINE AND NEW
HAMPSHIRE... BUT MOST OF THE ENERGY WILL BE TO THE NORTH. RAIN
CHANCES WILL BE LIMITED TO THE MOUNTAINS. SOUTHWEST FLOW AROUND
THE TROUGH AND AROUND THE BACK SIDE OF THE DEPARTING SURFACE HIGH
WILL ADVECT WARMER AIR INTO NORTHERN NEW ENGLAND. EXPECT HIGHS IN
THE 50S WIDESPREAD ESPECIALLY MONDAY AND TUESDAY.
ANOTHER WEAK WAVE CROSSES THROUGH THE SOUTHWESTERLY JET AND OVER
NORTHERN NEW ENGLAND ON TUESDAY WITH MORE WIDESPREAD LIGHT RAIN
EXPECTED. ONSHORE SOUTHERLY FLOW WILL AID IN MOISTURE TRANSPORT
AND ADD OROGRAPHIC LIFT TO INCREASE PRECIPITATION CHANCES.
MODELS DIVERGE ON HOW TO HANDLE THE FINAL PIECE OF THE LARGE SCALE
TROUGH THAT DIGS THROUGH THE SOUTHERN PLAINS ON TUESDAY. GFS IS
MORE PROGRESSIVE... WITH THE ENTIRE TROUGH AXIS SHIFTING EASTWARD
ON WEDNESDAY AND A SURFACE LOW STRENGTHENING RAPIDLY OVER NEW
ENGLAND. UNDER THIS SCENARIO... COLD AIR WILL REMAIN TO THE
NORTHWEST AND PRECIPITATION WILL BE MOSTLY RAIN BEFORE THE TROUGH
AXIS AND SURFACE FRONT PUSH THROUGH ON WEDNESDAY... CHANGING RAIN
TO SNOW BEFORE ENDING. HOWEVER... THE ECMWF ONLY EJECTS A PIECE OF
THE ENERGY FROM THE MAIN TROUGH AXIS ON WEDNESDAY... RESULTING IN
LESS EXTREME SURFACE FEATURES OVER OUR REGION... AND A MORE
QUICKLY ADVANCING COLD FRONT. THE MAIN TROUGH FINALLY CROSSES OUR
AREA ON THURSDAY WITH A SURFACE LOW WELL OFFSHORE AND SNOW MAINLY
OVER SOUTHERN AND CENTRAL NEW ENGLAND. HAVE GONE MAINLY WITH THE
GFS SOLUTION WITH THIS FORECAST AS IT IS MORE CONSISTENT WITH
PRIOR RUNS... BUT THERE IS SOME MERIT TO THE ECMWF SCENARIO AS
TROUGHS WHICH DIG THAT FAR SOUTH TEND TO SLOW DOWN AND TAKE LONGER
TO FINALLY GET PUSHED EASTWARD IN THE FLOW.
&&
.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
SHORT TERM...BRIEF MVFR CONDITIONS POSSIBLE UNTIL SUNRISE...
OTHERWISE VFR CONDITIONS AND LIGHT WINDS WILL PREVAIL THROUGH
TONIGHT.
LONG TERM...VFR THROUGH MONDAY. MAY SEE IFR CEILINGS AND RAIN
DEVELOPING TUESDAY.
&&
.MARINE...
SHORT TERM...SCA FOR SEAS OF 5 FT OR HIGHER WILL CONTINUE THROUGH
5 PM.
LONG TERM...SOUTHWEST FLOW PERSISTS AROUND DEPARTING HIGH
PRESSURE. FLOW WILL STRENGTHEN AS FRONT AND UPPER TROUGH APPROACH
FOR WEDNESDAY. SEAS GENERALLY HOVERING RIGHT AROUND THE 5 FT
THRESHOLD TUESDAY ONWARD.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 5 PM EST THIS
AFTERNOON FOR ANZ150-152-154.
&&
$$
HANES/KIMBLE
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
344 AM CST SAT DEC 3 2011
.SHORT TERM...TODAY THROUGH MONDAY NIGHT
343 AM CST SAT DEC 3 2011
MAIN FORECAST CONCERN IS ON MIXED PRECIPITATION THROUGH
TONIGHT...ALONG WITH SNOWFALL AMOUNTS.
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND 500MB HEIGHT ANALYSIS
SHOWED RIDGING OVER THE EAST PACIFIC...SPLIT TROUGHING FROM
MANITOBA SOUTHWEST INTO ARIZONA...AND BUILDING RIDGING FROM THE
SOUTHEASTERN U.S. INTO THE GREAT LAKES REGION. WITHIN THE SPLIT
TROUGHING...A POTENT SHORTWAVE WAS NOTED OVER SOUTHWEST NEW MEXICO
WITH A NICE BAROCLINIC LEAF ON WATER VAPOR NORTHEAST OF IT. 850MB
WINDS FAIRLY STRONG AHEAD OF THE SPLIT TROUGHING...RANGING FROM
40-60 KNOTS OUT OF THE SOUTH-SOUTHWEST FROM TEXAS INTO KANSAS AND
NORTHEAST INTO THE FORECAST AREA. THESE WINDS HAVE BEEN RAPIDLY
ADVECTING WARMER AIR AND MOISTURE NORTHWARD...CAUSING RAIN TO
BREAK OUT ACROSS IOWA...FAR SOUTHEASTERN MINNESOTA AND MUCH OF
WISCONSIN EXCLUDING THE NORTHWEST PART. 08Z PRECIPITABLE WATER
ANALYSIS FROM THE RUC SHOWS VALUES OF 0.75 TO 0.9 INCHES IN THE
SOUTHERN PORTION OF THE FORECAST AREA...OR ABOUT 200 PERCENT ABOVE
NORMAL. 2 METER AIR TEMPERATURES HAVE CLIMBED TO AT OR ABOVE 32F
AT MOST LOCATIONS AND DEWPOINTS ARE ALMOST THE SAME NOW. THIS
SHOULD BE REDUCING THE FREEZING OF THE RAIN AT THE SURFACE.
TODAY AND TONIGHT...SHORTWAVE OVER NEW MEXICO IS FORECAST TO
GRADUALLY ACCELERATE TO THE NORTHEAST DURING THIS PERIOD AS
A POTENT SHORTWAVE DROPS DOWN INTO MONTANA. INITIAL ISENTROPIC
LIFTING TAKING PLACE TO PRODUCE CURRENT PRECIPITATION SHOULD HOLD
FAIRLY STEADY THROUGH THE MORNING. WITH WARM ADVECTION OCCURRING...
ANY FREEZING OF THE PRECIPITATION SHOULD BE LIMITED TO BEFORE
13Z...THEN RAIN/DRIZZLE IS ANTICIPATED. DURING THE AFTERNOON...LOW
TO MID-LEVEL FRONTOGENESIS WILL INTENSIFY OVER THE SOUTHWEST
PORTION OF THE FORECAST AREA...SPREADING NORTHEAST DURING THE
EVENING. THIS FRONTOGENESIS IS CAUSED BY A COMBINATION FROM THE
DPVA PRODUCED AHEAD OF THE APPROACHING NEW MEXICO SHORTWAVE...AS
WELL AS A NEAR COUPLED UPPER JET STRUCTURE DEVELOPING. IN
ADDITION...CROSS-SECTIONS INDICATE THE PRESENCE OF SOME NEGATIVE
EPV ON TOP OF THE FRONTOGENESIS ZONE...ALLOWING FOR POTENTIAL FOR
A FEW CONVECTIVE ELEMENTS. WITH PRECIPITABLE WATER VALUES HOLDING
FAIRLY STEADY INTO THE EVENING...NEEDLESS TO SAY THE LATE
AFTERNOON INTO THE EVENING PERIOD IS OF MOST CONCERN FOR HEAVIEST
PRECIPITATION. GIVEN THE HIGHER PRECIPITATION RATES ALLOWING FOR
DIABATIC COOLING AND THE SURFACE FLOW TURNING NORTHERLY TO ALLOW FOR
COLD ADVECTION...THE AFTERNOON AND EVENING PRECIPITATION SHOULD
GRADUALLY CHANGE OVER TO SNOW...QUICKEST OVER THE NORTHWEST HALF
OF THE FORECAST AREA. 03.00Z MODEL QPF SPREADS ARE SOMEWHAT
HIGH...RANGING FROM 0.20-0.60 INCHES FOR 18-06Z. STILL...WITH SNOW
TO WATER RATIOS LIKELY TO STAY AROUND A 10 TO 1 AVERAGE GIVEN DEEP
AGGREGATION LAYER NOTED ON SOUNDINGS...LIKELY TO END UP WITH
SNOWFALL AMOUNTS IN THIS TIME WINDOW AT MOST UP TO 5 INCHES. SINCE
THIS IS AN INCH BELOW WARNING CRITERIA...AND MODELS TOO COLD
RIGHT NOW WITH HOURLY TEMPERATURES SUGGESTING PRECIPITATION COULD
END UP BEING EVEN MORE RAIN FOR THE AFTERNOON...AN ADVISORY SEEMS
TO BE THE BETTER REPLACEMENT FOR THE WATCH RIGHT NOW. DURING THE
OVERNIGHT HOURS...THE PRECIPITATION SHOULD SLOWLY START LIFTING TO
THE NORTHEAST WITH THE SHORTWAVE. HOWEVER...PLENTY OF LOW LEVEL
STILL EXISTS. THIS BRINGS UP A CONCERN...AS ONCE THE SHORTWAVE
MOVES IN THE ICE MAY SCOUR OUT...RESULTING IN RAIN/FREEZING RAIN.
THE BEST CHANCE FOR THIS TO OCCUR IS EAST OF A LINE FROM CHARLES
CITY IOWA TO LA CROSSE AND WISCONSIN RAPIDS. DID PUT IN A FEW
HUNDREDTHS OF ICE ACCUMULATION NEAR THIS LINE. WITH THE ICE
ACCUMULATION AND TO ADD A BUFFER IN CASE THE PRECIPITATION CHANGES
TO SNOW QUICKER TONIGHT...ADDED ANOTHER ROW OF COUNTIES JUST EAST
OF THE PREVIOUS WATCH FOR AN ADVISORY. REGARDING TEMPERATURES...
INCREASED THEM BOTH TODAY AND TONIGHT GIVEN CURRENT WARMER TRENDS.
SUNDAY THROUGH MONDAY NIGHT...MUCH QUIETER TIME PERIOD. SHORTWAVE
TROUGHING DIGGING INTO MONTANA TONIGHT IS FORECAST BY ALL MODELS
TO MARCH SLOWLY EAST...REACHING THE WESTERN END OF THE FORECAST
AREA AROUND 12Z TUESDAY. ALTHOUGH THE FORECAST AREA RESIDES IN
SOUTHWEST FLOW ALOFT...ALL OF THE SHORTWAVES IN THAT SOUTHWEST
FLOW TO HELP PRODUCE PRECIPITATION LOOK TO STAY TO THE SOUTHEAST
OF HERE. IN ADDITION...THE SHORTWAVE MOVING THROUGH TONIGHT HELPS
TO SCOUR OUT MUCH OF THE MOISTURE...NOTED BY PRECIPITABLE WATER
VALUES FALLING TO 0.25 INCH OR LESS BY 21Z SUNDAY. DID MAINTAIN
SOME LOW 20-30 PERCENT CHANCES FOR THE EASTERN TWO THIRDS OF THE
FORECAST AREA ON SUNDAY...DUE TO LINGERING LOW LEVEL LIFT.
AGAIN...THE PRESENCE OF ICE IS QUESTIONABLE...ESPECIALLY OVER
NORTHEAST IOWA AND SOUTHWEST WISCONSIN. AS A RESULT...HAVE
MENTIONED A SNOW/FREEZING DRIZZLE MIX. AFTER THAT...DRY WEATHER
WILL BE THE RULE...WITH ONLY SOME INCREASE OF MID/HIGH CLOUDS AS
THE MONTANA SHORTWAVE TROUGHING APPROACHES. BIGGER IMPACT
TEMPERATURES. 850MB TEMPS AT 12Z SUNDAY SHOULD RANGE FROM -4C EAST
TO -8C WEST. THESE COOL THROUGH THE DAY SUNDAY...SO HIGHS SHOULD
END UP CLOSE TO THE MORNING LOWS. FURTHER COOLING OF 850MB TEMPS
IS PROGGED FOR MONDAY...DROPPING TO -10 TO -14C. THEREFORE...
HIGHS IN MOST LOCATIONS LOOK TO ONLY TOP OUT IN THE 20S. MORE
TEENS AND SINGLE DIGIT READINGS ABOVE ZERO EXPECTED AT NIGHT WITH
NOCTURNAL COOLING.
.LONG TERM...TUESDAY THROUGH FRIDAY NIGHT
343 AM CST SAT DEC 3 2011
03.00Z ECMWF/GFS/CANADIAN AND GFS ENSEMBLES CONTINUE TO PAINT A
COLDER THAN NORMAL PATTERN FOR THE FORECAST AREA AS A POLAR VORTEX
SETS UP OVER HUDSON BAY BY LATE IN THE WEEK. SHORTWAVE TROUGH WILL
MOVE EAST TO WEST ACROSS THE AREA ON TUESDAY...NOT REALLY BRINGING
ANY PRECIPITATION WITH IT DUE TO LACK OF MOISTURE. HOWEVER...850MB
TEMPS FALL FURTHER...DOWN TO -11 TO -15C. BRIEF WARMING SHOULD OCCUR
TUESDAY NIGHT AS A WEAK UPPER RIDGE CROSSES IN THE WAKE OF TUESDAYS
SHORTWAVE TROUGH. THEN THIS GETS REPLACE BY A ZONAL FLOW FOR
WEDNESDAY INTO THURSDAY IN RESPONSE TO A SERIES OF SHORTWAVES
CROSSING SOUTHERN CANADA. THIS FLOW SETUP SHOULD ALLOW FOR DRY BUT
COOL CONDITIONS TO CONTINUE. ALL MODELS THEN INDICATE A DEEP
TROUGH DROPPING SOUTH THROUGH THE NORTHERN PLAINS THURSDAY NIGHT.
AHEAD OF THIS TROUGH...SOME PRECIP COULD OCCUR DUE TO DPVA AND
ISENTROPIC LIFT...THOUGH MOISTURE AGAIN IS QUESTIONABLE. INCLUDED
A 20 PERCENT CHANCE OF SNOW ACROSS THE SOUTHERN PORTIONS OF THE
FORECAST AREA...IN-LINE WITH THE 03.00Z GFS/ECMWF. THE UPPER
TROUGHING MOVES INTO THE AREA ON FRIDAY...BRINGING AIR MORE OF
ARCTIC ORIGIN ACROSS WITH 850MB TEMPS TANKING TO AROUND -20C. FOR
NOW FOLLOWED A CONSENSUS OF GUIDANCE FOR HIGHS AND LOWS THROUGHOUT
THE LONG TERM FORECAST...BUT MAY NEED TO LOWER HIGHS/LOWS FOR
FRIDAY AND FRIDAY NIGHT IF THIS -20C AT 850MB AIRMASS FORECAST
PERSISTS.
&&
.AVIATION...
1130 PM CST FRI DEC 2 2011
LOW STRATUS HAS MANIFESTED ACROSS IA IN THE PRESENCE OF LOW LEVEL
SATURATION/WARMING AND SOME MOISTURE TRANSPORT...AND HAS ADVECTED
OVER KRST/KLSE. KRST IS ON THE EDGE OF THE MVFR CEILINGS...BUT
RUC13/NAM12 SUGGESTS THAT IT SHOULD HOLD ACROSS KRST THROUGH
SATURDAY. VFR JUST TO THE WEST THOUGH...AND SEE SOME POTENTIAL FOR
AN IMPROVEMENT IN CEILINGS AT BOTH LOCATIONS FOR LATE MORNING/EARLY
AFTERNOON AS INITIAL SURGE OF MOISTURE/WARM AIR ADVECTION MOVES OFF
TO THE NORTHEAST. WILL KEEP MVFR FOR NOW...BUT IT WILL HAVE TO BE
MONITORED. MVFR/IFR THEN RETURNS TONIGHT AS THE MAIN PORTION OF THE
STORM SYSTEM MOVES IN.
FOR PCPN...TEMPS ARE WARMING MORE THAN MODELS PREVIOUSLY
SUGGESTED...AND LOOK A BIT WARMER FOR MUCH OF THE DAY SAT. SMALL
CHANGES BUT BIG IMPACTS ON PCPN TYPE. WILL ADJUST FOR ANY CHANGE
OVER TO ALL -SN TO LATER IN THE DAY AS A RESULT. IN ADDITION...NAM12
AND SOME OTHER SHORT TERM MODELS POINT TO A RELATIVE DRY PERIOD IN
THE MIDDLE PART OF THE DAY. BELIEVE THIS IS REASONABLE AND WILL TRIM
THE TAFS THIS WAY. IF SOMETHING WOULD FALL...IT SHOULD BE LIGHT. THE
HEAVY PCPN AND CHANGE OVER TO ALL SNOW WILL OCCUR LATE THIS
AFTERNOON/EARLY EVENING. VSBYS 1-2SM IN THE -SN CAN BE
EXPECTED...WITH SEVERAL INCHES OF ACCUMULATION BY SUN MORNING.
HIGHER AMOUNTS AT KRST. WINDS WILL SWING FROM THE SOUTH TO NORTHWEST
NEAR 00Z...AND COULD INCREASE OVERNIGHT. SNOW SHOULD BE WET
THOUGH...PREVENTING MUCH OF THE BLOWING/DRIFTING POTENTIAL.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
343 AM CST SAT DEC 3 2011
WI...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 AM CST
SUNDAY FOR WIZ041>044-053.
FREEZING RAIN ADVISORY UNTIL 7 AM CST THIS MORNING FOR WIZ029-
032>034-041>044-053>055-061.
WINTER WEATHER ADVISORY FROM NOON TODAY TO 6 AM CST SUNDAY FOR
WIZ017-029-032>034.
MN...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 AM CST
SUNDAY FOR MNZ096.
FREEZING RAIN ADVISORY UNTIL 7 AM CST THIS MORNING FOR MNZ079-
086>088-094>096.
WINTER WEATHER ADVISORY FROM NOON TODAY TO 6 AM CST SUNDAY FOR
MNZ079-086>088-094-095.
IA...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 AM CST
SUNDAY FOR IAZ010-011-019-029.
FREEZING RAIN ADVISORY UNTIL 7 AM CST THIS MORNING FOR
IAZ008>011-018-019-029-030.
WINTER WEATHER ADVISORY FROM NOON TODAY TO 6 AM CST SUNDAY FOR
IAZ008-009-018.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION..... RIECK
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
1047 PM CST FRI DEC 2 2011
.UPDATE...
THINGS ARE LOOKING ON SCHEDULE. PRECIP IS BREAKING OUT QUICKLY
ACROSS IOWA AND WILL BE CROSSING THE RIVER BY OR SHORTLY AFTER
MIDNIGHT...THEN RACING THROUGH THE REMAINDER OF THE CWA OVERNIGHT.
TEMPS DROPPED TO THEIR MINS EARLY THIS EVENING AS CLEAR SKIES AND
LOW DEWPOINTS DID THEIR JOB. BUT THICKENING CIRRUS CANOPY AND
ADVANCING LOW CLOUDS HAVE REVERSED THE TREND WITH TEMPS RISING
NOW. TEMPS SHOULD BE ABOVE FREEZING BY THE TIME THE PRECIP
ARRIVES. SOME ROAD SURFACE TEMPS MAY LINGER BELOW FREEZING
INITIALLY AND CAUSE SOME ICING FOR A BRIEF TIME. OTHERWISE...THIS
IS A RAIN EVENT. OTHER THAN INCREASING POPS LATER TONIGHT...NO
MAJOR CHANGES WERE MADE TO THE FORECAST TONIGHT.
&&
.AVIATION/06Z TAFS/...
A MIX OF MVFR/IFR CIGS ARE ADVANCING QUICKLY INTO SOUTHWEST
WISCONSIN LATE THIS EVENING AND THESE SHOULD CONTINUE RIGHT ACROSS
THE FORECAST AREA OVERNIGHT. I THINK WE/LL KEEP THE CIGS JUST
ABOVE THE IFR THRESHOLD FOR NOW...RIGHT AROUND 1200FT...BUT WE
COULD SEE SOME PERIODS OF IFR CIGS IN THE RAIN. AS STATED IN THE
EARLIER AVIATION DISCUSSION...THERE WILL BE A PERIOD OF MORNING
RAIN...FOLLOWED BY A LULL IN THE ACTIVITY DURING THE LATE MORNING
AND AFTERNOON...ESPECIALLY EAST OF KMSN. NOT CONFIDENT WE WILL SEE
CIGS IMPROVE A WHOLE LOT...BUT IT/S POSSIBLE THEY COULD LIFT TO
VFR LEVELS FOR A SHORT TIME. THEN DROP BACK DOWN AS THE COLD FRONT
SWEEPS THROUGH IN THE EVENING.
&&
.PREV DISCUSSION... /ISSUED 329 PM CST FRI DEC 2 2011/
SHORT TERM...
TONIGHT AND SATURDAY...FORECAST CONFIDENCE MEDIUM TO HIGH
SHORTWAVE ENERGY EJECTING OUT OF A TROUGH IN THE SOUTHWEST U.S. WILL
BRING A PLUME OF MOISTURE INTO WISCONSIN TONIGHT THROUGH SUNDAY
MORNING. THIS PLUME IS APPARENT IN THE LATEST WATER VAPOR IMAGERY.
THIS TROUGH/SHORTWAVE WILL PHASE WITH A NORTHERN STREAM TROUGH OVER
THE WEEKEND...CREATING A PROLONGED PRECIP EVENT ACROSS WISCONSIN.
MODELS ARE IN FAIR AGREEMENT ABOUT WAITING UNTIL AFTER MIDNIGHT FOR
THE WALL OF WATER...OR DEEP MOISTURE...TO REACH SOUTH CENTRAL WI.
WHILE THERE MAY BE SOME PRECIP IN THE FORECAST AREA BEFORE 3
AM...THE MAIN SURGE WILL HIT MOST OF THE AREA BETWEEN 3 AND 6 AM.
THE PRECIP MAY HOLD OFF IN KENOSHA AND MILWAUKEE UNTIL RIGHT AROUND
6 AM/12Z. UPPER LEVEL DIVERGENCE INCREASES TONIGHT ALONG WITH
MODERATE 700MB UPWARD MOTION. ISENTROPIC LIFT SEEN ON THE 290K
ISENTROPIC LEVEL WITH CONDENSATION PRESSURE DEFICITS BELOW 5 MB ON
THE NAM BY SUNRISE SATURDAY.
PRECIP WILL MAINLY BE IN THE FORM OF RAIN IN THE ENTIRE FORECAST
AREA. THE ONLY EXCEPTION WILL BE AROUND THE DELLS AND GREEN
LAKE/MARQUETTE COUNTIES WHERE THE EVENT COULD BEGIN AS SNOW AND
SWITCH TO RAIN. WITH THE STRONG WARM AIR ADVECTION...SFC TEMPS ARE
EXPECTED TO WARM TO JUST ABOVE FREEZING WITH THE ONSET OF
PRECIPITATION...THUS LIMITING THE FREEZING RAIN OR SNOW POTENTIAL.
THE CENTER OF THE SURFACE LOW PRESSURE WILL TRACK RIGHT ACROSS SOUTH
CENTRAL WI LATE SAT AFTERNOON INTO SUNDAY MORNING...SO A LULL IN THE
PRECIPITATION IS EXPECTED IN SOUTHEAST WI...EAST OF MADISON. THE
LULL SHOULD BE FROM AROUND 2 PM SAT THROUGH SAT EVENING IN
MILWAUKEE. CLOUD COVER DURING THIS TIME IS UNCERTAIN...AS MODELS
SUGGEST CLEARING AND EXPERIENCE SUGGESTS STRATUS CLOUDS AND POSSIBLY
LIGHT FOG.
SATURDAY NIGHT THROUGH MONDAY...FORECAST CONFIDENCE MEDIUM TO HIGH
THE SHORTWAVE TROUGH LIFTING NEWD THROUGH THE GREAT PLAINS WILL
REACH NRN WI BY 12Z SUN AND WILL AID IN MINOR DEEPENING OF THE SFC
LOW AS IT TRACKS FROM ERN KS TO SE WI. A DRY SLOT WILL INITIALLY
BE OVER ERN WI SAT EVENING BUT WILL SHIFT EWD WITH A 60 KT LOW
LEVEL JET STREAM TO BRING A NEW SURGE OF WARM AND MOIST ADVECTION
AND SFC-850 MB FRONTOGENESIS. PWS TO INCREASE TO 0.80-0.90 INCHES WITH
WIDESPREAD MDT RAIN EXPECTED. THE CONSENSUS OF THE THERMAL FIELDS
WILL BRING A MIXTURE OF LGT RAIN AND LGT SNOW TO THE FAR WRN CWA
BETWEEN 09-12Z. PCPN TO QUICKLY DIMINISH SUN AM AS THE LOW LEVEL
JET STREAM SHIFTS INTO LOWER MI. LIKELY POPS EXPECTED EARLY IN
THE DAY FOR THE NE CWA WITH CHANCES ELSEWHERE. LGT RAIN WILL
CHANGE TO OR MIX WITH LGT SNOW BUT SNOW ACCUMULATIONS WILL LIKELY
REMAIN UNDER ONE HALF INCH IN THE NRN AND WRN CWA WITH TRACE
AMOUNTS AT BEST IN SE WI.
COLD AND DRY ADVECTION AND SUBSIDENCE SHOULD BE ENOUGH FOR CLOUD
COVER TO BECOME FEW-SCATTERED FOR SUN NT INTO MONDAY. A WEAKENING
LOW PRESSURE AREA AND SHORTWAVE TROUGH WILL THEN MOVE FROM THE NRN
PLAINS INTO THE GREAT LAKES FOR MONDAY. THE ONLY RESULT WILL BE A
DRY COLD FRONT WITH THE UPSTREAM POLAR HIGH OVER THE NRN AND
CENTRAL GREAT PLAINS.
LONG TERM...
TUESDAY THROUGH FRIDAY...FORECAST CONFIDENCE MEDIUM
A HIGH PRESSURE RIDGE ASSOCIATED WITH THE POLAR HIGH OVER THE
CENTRAL PLAINS WILL MOVE ACROSS WI FOR TUE/TUE NT WHILE A LONG
WAVE UPPER TROUGH AND SFC TROUGH BRINGS PCPN TO SRN AND ERN UNITED
STATES. FOR THE REMAINDER OF THE WEEK A STRONG AND VERY LARGE
CYCLONE WILL MOVE ACROSS NRN CANADA AND OCCLUDE OVER AND NORTH OF
THE HUDSON BAY AREA LATER IN THE WEEK. THE NRN USA WILL BE ON THE
SRN FRINGES OF THIS CYCLONE WITH DRY WNWLY WINDS AND GRADUAL COLD
ADVECTION. DURING THIS TIME A 1040 MB ARCTIC HIGH WILL SLIDE SWD
ALONG THE LEE OF THE CANADIAN ROCKIES AND EVENTUALLY INTO THE MID
MO RIVER VALLEY ON FRI. SLIGHTLY BELOW NORMAL TEMPS ARE EXPECTED
LATER NEXT WEEK WITH THE LACK OF SNOW COVER INHIBITING GREATER
COOLING.
AVIATION/00Z TAFS/...
CLEAR SKIES THROUGH THE EVENING UNDER THE HIGH PRESSURE. HOWEVER
SOUTH WINDS DEVELOPING AHEAD OF LOW PRESSURE FROM WESTERN OKLAHOMA
TO MINNESOTA WILL BRING INCREASING/THICKENING AND LOWERING HIGH/MID
LEVEL CLOUDS THIS EVENING...FOLLOWED BY MVFR/IFR CIGS AND VSBYS...
ESPECIALLY IN SOUTH CENTRAL WISCONSIN DURING THE EARLY MORNING HOURS
SATURDAY. SOME FREEZING RAIN POTENTIAL MAINLY NORTH AND WEST OF
MADISON TO NEAR FOND DU LAC.
THERE WILL BE A LULL IN THE PRECIP SAT AFTERNOON. NOT SURE IF
CEILINGS WILL TANK WITHIN THE LULL AS THE SFC LOW MOVES OVERHEAD
DURING THIS TIME. LOW CIGS EXPECTED EARLY SAT EVENING...WHICH SHOULD
COME UP A BIT WHEN THE NEXT ROUND OF PRECIP HITS. PRECIP TYPE SHOULD
BE ALL RAIN FROM TONIGHT THROUGH SATURDAY NIGHT AT ALL TAF SITES.
LOW LEVEL WIND SHEAR EXPECTED TONIGHT INTO SATURDAY MORNING AS LOW
LEVEL JET MOVES OVERHEAD. NAM IS STRONGER WITH THE WINDS THAN THE
GFS...AND RUC IS IN BETWEEN. LLWS WILL BE POSSIBLE ONCE AGAIN SAT
NIGHT AS A NEW SURGE OF WARM AIR ADVECTION MOVES INTO SOUTHEAST WI.
MARINE...
SOUTH WINDS WILL INCREASE TONIGHT AND WINDS AND WAVES ARE EXPECTED
TO REACH LOWER-END SMALL CRAFT ADVISORY CONDITIONS LATE TONIGHT INTO
SATURDAY. WINDS AND WAVES WILL BE HIGH THROUGH SATURDAY
MORNING...THEN THERE WILL BE A LULL IN THE WINDS SATURDAY AFTERNOON
AS THE SURFACE LOW CROSSES SOUTHEAST WISCONSIN. WEST WINDS WILL
INCREASE BEHIND THE LOW ONCE AGAIN SAT NIGHT THROUGH AT LEAST MIDDAY
SUNDAY. A SMALL CRAFT ADVISORY IS IN EFFECT FROM 06Z TONIGHT THROUGH
18Z SUNDAY.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL NOON CST SUNDAY FOR LMZ643>646.
&&
$$
UPDATE...DAVIS
TONIGHT/SATURDAY AND AVIATION/MARINE...MRC
SATURDAY NIGHT THROUGH FRIDAY...GEHRING
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1015 PM MST FRI DEC 2 2011
.AVIATION...06Z TAFS
IFR/LIFR CONDITIONS TO CONTINUE OVERNIGHT WITH LIGHT SNOW. SNOW
WILL COME TO AN END BY MID MORNING. LATEST HRRR GUIDANCE KEEPS IFR
GOING FOR OUR WYOMING AIRPORTS THROUGH 15Z OR SO WITH THE NORTHERN
PANHANDLE STAYING VFR.
CLAYCOMB
&&
.PREV DISCUSSION... /ISSUED 834 PM MST FRI DEC 2 2011/
UPDATE...
GETTING NEW SNOW REPORTS OUT OF RAWLINS WITH 3 INCHES OF NEW SNOW ALREADY
THIS EVENING. LATEST SATELLITE IMAGERY CONTINUES TO SHOW COOLING
AND EXPANDING COLD CLOUD TOPS OVER CARBON COUNTY. LATEST NAM
SHOWING SOME BANDING OF SNOW WITH ADDITION 3-5 INCHES OF SNOW
POSSIBLE OUT THAT WAY. WENT AHEAD WITH AN UPGRADE TO THE SNOW
ADVISORIES TO A WINTER STORM WARNING FOR THE I80 CORRIDOR FROM
LARAMIE TO RAWLINS. LATEST WRF.NAM ALSO SHOWING HIGHER SNOW
AMOUNTS OVER LARAMIE COUNTY OVERNIGHT...SO WENT AHEAD AND EXPANDED
THE SNOW ADVISORY FURTHER EAST TO COVER LARAMIE AND PLATTE
COUNTIES. UPDATES HAVE BEEN SENT.
CLAYCOMB
&&
PREV DISCUSSION... /ISSUED 315 PM MST FRI DEC 02 2011/
SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT.
TONIGHT...NEXT SHORTWAVE TROUGH MOVES ACROSS OVERNIGHT AFTER ANOTHER
COLD FRONTAL SURGE. LOOKS LIKE ENOUGH DYNAMICAL LIFT COMBINED WITH
UPSLOPE TO PRODUCE WIDESPREAD LIGHT TO MODERATE SNOW WEST OF A
DOUGLAS TO KIMBALL LINE. WITH PROGGED QPFS ON THE NAM AND GFS AS
WELL AS EXPECTED SNOWFALL RATIOS OF 15 TO 1 IN THE COLD AIRMASS...AS
WELL AS THE HPC SNOWFALL GUIDANCE...WE ANTICIPATE LOW END WINTER
WEATHER ADVISORIES ROUGHLY WEST OF A DOUGLAS TO CHEYENNE LINE WITH
THE SNOWFALL EVENT ENDING BY EARLY SATURDAY AFTERNOON. FORTUNATELY...
WINDS WILL BE RELATIVELY LIGHT...THUS MINIMAL BLOWING AND DRIFTING
OF THE SNOW.
SATURDAY...SNOW WILL GRADUALLY END AND DISSIPATE FROM NORTH TO SOUTH
AS THE SHORTWAVE TROUGH ALOFT MOVES OVER COLORADO AND MOISTURE AND
LIFT WANE. COLDER DAY IN THE WAKE OF THE COLD FRONT WITH HIGH
TEMPERATURES IN THE TEENS AND 20S WITH 700 MB TEMPERATURES NEAR -14
CELSIUS.
SATURDAY NIGHT...ALBERTA CLIPPER SHORTWAVE TROUGH ALOFT MOVES
SOUTHEAST ACROSS MONTANA AND NORTH DAKOTA...INDUCING SURFACE LOW
PRESSURE ACROSS WESTERN NORTH DAKOTA. DECENT SURFACE THROUGH 700 MB
GRADIENTS DEVELOP THUS WILL SEE SOME AREAS OF BLOWING SNOW CAUSED BY
WINDS PICKING UP ALONG AND WEST OF INTERSTATE 25 IN TYPICALLY WIND
PRONE AREAS.
SUNDAY...ANOTHER REINFORCING SHOT OF COLD AIR MOVES ACROSS OUR
COUNTIES IN THE WAKE OF A COLD FRONT. NEXT SHORTWAVE TROUGH ALOFT
AND ADEQUATE LOW AND MID LEVEL MOISTURE WILL PRODUCE LIGHT TO
MODERATE SNOW ACROSS OUR WYOMING COUNTIES...ESPECIALLY WEST OF
INTERSTATE 25. EXPECT SNOWFALL AMOUNTS OF 1 TO 2 INCHES AT LOWER
ELEVATIONS WITH 3 TO 5 INCHES OVER THE SNOWY AND SIERRA MADRE RANGES.
SUNDAY NIGHT...SNOW SHOWERS WILL DECREASE IN AREAL COVERAGE AS THE
UPPER TROUGH MOVES ACROSS COLORADO AND LIFT DECREASES. COLD NIGHT
WITH THE MOTHERLODE 700 MB TEMPERATURES NEAR -22 CELSIUS OVERHEAD
THOUGH LOOKS LIKE ENOUGH CLOUD COVER WILL ACT AS A BLANKET TO LIMIT
POTENTIAL LOW TEMPERATURES.
LONG TERM...MONDAY THROUGH FRIDAY...
EXTENDED FORECAST PERIOD TO START OUT ON THE QUIET SIDE. EXPANSIVE
UPPER RIDGE WILL BUILD ACROSS THE NORTHWEST UNITED STATES STARTING
EARLY NEXT WEEK. FOLLOWING A COLD WEEKEND...WARM AIR WILL SPREAD
INTO THE AREA AS THE RIDGE BUILDS. SNOW COVER OVER THE AREA WILL
KEEP TEMPERATURES FROM REACHING THEIR FULL POTENTIAL BUT SHOULD
EASILY SEE HIGH TEMPERATURES BACK INTO THE 30S TUESDAY EAST OF THE
LARAMIE RANGE...AND POSSIBLY SOME 40S SHOULD WESTERLY DOWNSLOPE IN
PLACE. WEDNESDAY SHOULD BE THE WARMEST DAY OF THE WEEK WITH 40S
EAST. INCREASED TEMPERATURES OVER THE CONSENSUS GUIDANCE WEDNESDAY
BUT EVEN THIS MAY NOT BE WARM ENOUGH UNDER WESTERLY FLOW AND 700 MB
TEMPERATURES APPROACHING ZERO DEGREES CELSIUS. DRY MONDAY THROUGH
WEDNESDAY BUT SMALL CHANCES FOR SNOW RETURN THE LAST PORTIONS OF THE
WEEK. UPPER TROUGH TO DIG INTO THE NORTHERN PLAINS LATE NEXT WEEK.
THE QUESTION IS HOW FAR SOUTH AND WEST THIS FEATURE WILL MAKE IT.
LATEST GFS AND EC BOTH KEEP THE BUILD OF THE SHORTWAVE ENERGY MOVING
THROUGH THE UPPER TROUGH NORTH OF THE FORECAST AREA...SO MAY STAY DRY
ALL NEXT WEEK.
FIRE WEATHER...NO FIRE WEATHER CONCERNS. SNOW TO SPREAD ACROSS MOST
OF THE FIRE WEATHER FORECAST AREA TONIGHT.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING UNTIL 5 AM SATURDAY FOR WYZ109-WYZ110-
WYZ113-WYZ114-WYZ115.
WINTER WEATHER ADVISORY UNTIL 2 PM SATURDAY FOR WYZ103-WYZ104-
WYZ105-WYZ106-WYZ107-WYZ111-WYZ112-WYZ116-WYZ117-WYZ118.
NE...NONE.
&&
$$
SHORT TERM...RUBIN
LONG TERM/AVIATION...LIEBL
AREA FORECAST DISCUSSION
NWS DENVER CO
358 AM MST SAT DEC 3 2011
.UPDATE...AFTER FURTHER REVIEW I DECIDED TO INCLUDED ZNES 39 AND
40 IN THE WINTER WEATHER ADVISORY THROUGH 11 AM. ALTHOUGH THE SNOW
AMOUNTS WILL BE ON THE LOW SIDE OF THE ADVISY CRITERIA...BUT WIND
MAY COMPOUND THE PROBLEM FOR A TIME. HEAVIEST BAND OF SNOW APPEARS
TO BE FORMING JUST TO THE EAST OF D.I.A. AT THIS TIME. HRRR STILL
SHOWS THE HEAVIEST PCPN EVENTUALLY SHIFTING TO THE PALMER DIVIDE
AREA AFTER 15Z.
&&
.SHORT TERM...
.PREV DISCUSSION... /ISSUED 310 AM MST SAT DEC 3 2011/
SHORT TERM...STORM SYSTEM MOVING OVER THE REGION THIS MORNING.
SOME BANDED SNOWFALL HAD OCCURRED OVERNIGHT BUT NOT MUCH BANDED
ENHANCEMENT EVIDENT AT THIS TIME. MDLS INDICATE THE WEAK TO MDT QG
ASCENT AT THE SFC AND ALOFT WILL OCCUR PRIOR TO 18Z. WL CONTINUE
WITH THE CURRENT HIGHLIGHTS. SFC WINDS THIS MORNING HAVE BEEN NORTH
TO NORTHWESTERLY PRIMARILY. WITH THIS IN MIND...BEST AREAS FOR
SNOWFALL THIS MORNING WILL BE ALONG THE PALMER DIVIDE. AREAS OF
BLOWING SNOW MAY ALSO BE AN ISSUE OVER THE NORTHEAST PLAINS. IF
GUSTY WINDS OCCUR ALONG THE URBAN CORRIDOR IT WILL LIKELY BE ALONG
THE CHEYENNE RIDGE AND EAST OF INTERSTATE 25 FOR THE MOST PART. A
DRIER NORTHWESTERLY FLOW ALOFT WILL BE OVER THE CWFA TONIGHT.
CLEARING SKIES WILL ALLOW FOR OVERNIGHT LOWS TO DROP TO THE SINGLE
DIGITS.
LONG TERM...ANOTHER SHORT WAVE AND COLD FRONT WILL DROP SOUTH
ACROSS THE ROCKIES ON SUNDAY. THE WAVE WILL ENTER MONTANA SUNDAY
MORNING AND THEN DIVE SOUTH AND CLOSE OFF OVER THE FOUR CORNERS
SUNDAY NIGHT. THE COLD FRONT WILL MOVE THROUGH NORTHEAST COLORADO
AROUND MID DAY SUNDAY. BEST LIFT ASSOCIATED WITH THIS SYSTEM WILL BE
OVER WESTERN AND CENTRAL COLORADO. THERE WILL BE SOME WEAK UPSLOPE
BEHIND THE FRONT. THE HEAVIEST SNOW WILL FALL OVER THE MOUNTAINS AND
FOOTHILLS WITH JUST LIGHT AMOUNTS ALONG THE FRONT RANGE. THE EASTERN
PLAINS MAY EVEN MISS OUT.
AIRMASS BEHIND THE FRONT WILL BE COLD. TEMPERATURES AT 700MB BOTTOM
OUT AT -20C MONDAY MORNING. STRONG SURFACE HIGH...ABOUT 1040MB...
WILL SETTLE OVER THE AREA MONDAY. THIS WILL BRING CLEAR AND COLD
CONDITIONS MONDAY. MOST LOCATIONS WILL REMAIN IN THE TEENS DURING
THE DAY. MONDAY NIGHT WILL BE COLD WITH SOME LOCATIONS FALLING BELOW
ZERO FOR THE FIRST TIME THIS YEAR. DOWNSLOPE WINDS IN AND NEAR THE
FOOTHILLS WILL DEVELOP MONDAY NIGHT LEADING TO WARMING TEMPERATURES
DURING THE NIGHT.
TUESDAY AND WEDNESDAY WILL BE DRY AND COOL AS A WEAK RIDGE MOVES
ACROSS THE REGION. TEMPERATURES WILL WARM BUT REMAIN BELOW NORMAL
WITH HIGHS IN THE 30S TO MID 40S OVER NORTHEAST COLORADO. ANOTHER
TROUGH AND COLD FRONT WILL DROP SOUTH ACROSS THE STATE THURSDAY.
THIS WILL BRINGING COOLER AIR AND A CHANCE OF SNOW FOR THURSDAY AND
FRIDAY. THIS WILL BE MORE OF A GLANCING BELOW THAN THE PREVIOUS
SYSTEM. SO IT SHOULD NOT BE AS COLD AND IF IT SNOWS...SNOW AMOUNTS
WILL BE ON THE LOW SIDE.
&&
.AVIATION...NOT MUCH ADJUSTMENTS PLANNED TO THE ONGOING FORECASTS.
SFC VSBYS WILL GENERALLY HOVER BETWEEN 1-2 MILES THIS MORNING...WITH
THE CIGS LESS THAN 2K FT AGL...AND OCCASIONAL VSBYS LESS THAN 1 MILE
AND CIGS LESS THAN 1K FT. GUSTY NORTH TO NORTHWEST WINDS ARE STILL
POSSIBLE BETWEEN 12-18Z. CONDITIONS SHOULD GRADUALLY IMPROVE FM THE
NORTH AND WEST AFTER 18Z. LOWER VSBYS/CIGS WILL LINGER LONGEST OVER
CENTENNIEL AIRPORT WITH GRADUAL IMPROVEMENT THERE AFTER 21Z..
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 2 PM MST THIS AFTERNOON FOR COZ041-
045-046-049.
WINTER WEATHER ADVISORY UNTIL 11 AM MST THIS MORNING FOR COZ035-
036-038>040.
&&
$$
SHORT TERM...COOPER
LONG TERM....MEIER
AVIATION.....COOPER
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
806 AM CST SAT DEC 3 2011
.UPDATE...
DATA THROUGH 12Z SHOWS ALL MODELS ARE VERIFYING HORRIBLY COMPARED
TO REAL DATA. THERE IS A 1009 AND LIKELY A 1008MB LOW IN EXTREME
SOUTHEAST COLORADO. ALL MODELS SHOW AN ERROR DELTA OF 6-7MB IN
THEIR SFC FIELDS AT 12Z. ONLY THE RUC IS CLOSE BUT HAS THE LOW
SLIGHTLY IN ERROR ON POSITION. THUS WILL USE IT AS A TREND FOR THE
REMAINDER OF THE DAY.
CURRENT PRECIPITATION VERIFIES NICELY WITH THE 300K THETA SFC FROM
THE RUC IN TERMS OF FORCING AND CONDENSATION PRESSURE DEFICITS.
USING THIS AS A GUIDE...CATEGORICAL POPS WILL BE SEEN EVERYWHERE
THIS MORNING. THE CURRENT PRECIP IS BEING AIDED BY SOME FAIRLY
SUBSTANTIAL VORT MAXES IN NORTHERN MISSOURI ALONG WITH THE
ISENTROPIC LIFT.
RUC TRENDS INCLUDING THE CURRENT 12Z RUC SHOW THE FORCING
WEAKENING AND CONDENSATION PRESSURE DEFICITS RISING SIGNIFICANTLY
ROUGHLY EAST OF A KEOSAUQUA TO FREEPORT LINE DURING THE AFTERNOON
HOURS. THUS IT IS POSSIBLE THAT THE RAIN MAY END OVER ROUGHLY THE
EASTERN HALF OF THE CWFA DURING THE AFTERNOON HOURS. BY LATE
AFTERNOON THE RUC DOES SHOW CONDENSATION PRESSURE DEFICITS
COLLAPSING ALONG WITH FORCING INCREASING. THIS IS IN ASSOCIATION
WITH THE APPROACH OF THE SFC WAVE.
EXTRAPOLATION OF THE 12 HR RUC FCST SUGGESTS THAT THE SFC LOW WILL
TRACK FROM JUST WEST OF KMCI TO BETWEEN KALO AND KCID DURING THE
EVENING HOURS. IF THIS FURTHER WESTERN TRACK PLAYS OUT...THE
POTENTIAL FOR RAIN MIXING WITH AND CHANGING TO SNOW IN THE WESTERN
CWFA MAY NEED TO BE RE-VISITED WITH THE AFTERNOON FCST PACKAGE.
AN UPDATE TO THE CURRENT FCST HAS BEEN SENT.
..08..
&&
.PREV DISCUSSION... /ISSUED 553 AM CST SAT DEC 3 2011/
AVIATION...
CIGS WILL RANGE FROM IFR TO LOW END MVFR AT KCID/KDBQ WITH VSBYS
1-2SM THROUGH 18Z. VFR CIGS WITH PERHAPS BRIEF 2KFT CIGS WITH
3-5SM CAN BE EXPECTED AT KMLI/KBRL. A DECREASE IN RA INTENSITY IS
EXPECTED 18Z/03-00Z/04 WHICH WILL ALLOW VFR CONDITIONS AT
KMLI/KBRL. KCID/KDBQ WL KEEP 3-5SM WITH CIGS AOB 1KFT AGL. AFT
00Z/04 THE NEXT ROUND OF RA WILL ARRIVE AND DROP VSBYS TO 1-2SM WITH
CIGS AOB 1KFT. KCID/KDBQ MAY SEE A RASN MIX WITH A CHANGE TO ALL
SN AFT 06Z/04.
.08..
PREV DISCUSSION... /ISSUED 331 AM CST SAT DEC 3 2011/
SYNOPSIS...
06Z SFC ANALYSIS HAD A COLD FRONT FROM THE EASTERN DAKOTAS INTO
CENTRAL NEBRASKA. A LOW WAS IN EASTERN COLORADO WITH A FRONT INTO
SOUTHERN NEBRASKA. RADAR TRENDS SHOW A LARGE SHIELD OF WAA
ASSOCIATED WITH A WAVE FROM WISCONSIN BACK INTO WESTERN MISSOURI.
DEW POINTS WERE IN THE 30S AND 40S ACROSS MUCH OF THE MIDWEST WITH
20S OVER THE UPPER MIDWEST AND GREAT LAKES.
SHORT TERM...TODAY AND TONIGHT...
WAA HAS ALLOWED TEMPERATURES TO RISE AND PUSH WBZ SFC TEMPERATURES
TO ABOVE 34 FOR AREAS SOUTH OF HWY 20. ANY THREAT FOR FZRA OR FZDZ
WILL END BY SUNRISE AS WBZ TEMPERATURES CONTINUE TO RISE.
THE INITIAL WAA PRECIP SHIELD WILL MOVE ACROSS THE AREA DURING THE
MORNING HOURS. BASED ON RADAR AND RUC TRENDS THE OVERALL INTENSITY
OF THE PRECIP SHOULD DECREASE DURING THE MID TO LATE MORNING HOURS.
THE QUESTION THEN TURNS TO PRECIP CHANCES FOR THE AFTERNOON.
ALL MODELS SHOW CONDENSATION PRESSURE DEFICITS INCREASING DURING THE
AFTERNOON HOURS. FORCING WEAKENS AND CONVERGENCE IN THE LOWER LEVELS
EITHER WEAKENS OR IS NOT PRESENT. THUS PRECIP CHANCES WILL BE
GREATLY LOWER FOR MOST AREAS GENERALLY EAST OF A KEOK TO KFEP LINE
FOR MUCH OF THE AFTERNOON. THE POTENTIAL DOES EXIST THAT EASTERN
PARTS OF THE CWFA COULD GO COMPLETELY DRY DURING THE AFTERNOON
HOURS. THIS SCENARIO WILL HAVE TO BE RE-EVALUATED.
TONIGHT...THE MAIN SFC LOW ARRIVES AND BRINGS ANOTHER ROUND OF
PRECIPITATION TO THE AREA. WBZ TEMPERATURES ARE ABOVE 34 DEGREES SO
ALL PRECIPITATION WILL BE IN THE FORM OF RAIN DURING THE EVENING
HOURS. AFTER MIDNIGHT...THE RACE BEGINS WITH THE CAA TO SEE IF THE
PRECIP CAN MIX WITH AND CHANGE OVER TO SNOW PRIOR TO SUNRISE. THE
FAR NORTHWEST PART OF THE CWFA WOULD HAVE THE BEST CHANCE. MORE
INTERESTING IS THE DRY SLOT BEING DEPICTED BY THE MODELS. FORCING ON
THETA SURFACES 290-300K SHOW ALL FORCING ENDING VERY LATE TONIGHT
WHICH IS COINCIDENT WITH THE ARRIVAL OF THE DRY SLOT. THUS THE
POTENTIAL DOES EXIST THAT PRECIP MAY END PRIOR TO THE COLD AIR
ARRIVING. IF THIS WOULD OCCUR...THE POTENTIAL FOR A MIX OR A CHANGE
OVER IN THE NORTHWEST CWFA WOULD BE LOW.
IF THE PRECIPITATION DOES END...THE QUESTION THEN BECOMES WHETHER OR
NOT ANY FZDZ COULD DEVELOP. RIGHT NOW THE FCST SOUNDINGS DO NOT
SUGGEST THIS. THUS THE CURRENT THINKING IS THAT A MIX WILL DEVELOP
IN THE NORTHWEST WITH A QUICK CHANGE OVER BEFORE THE PRECIP ENDS.
AMOUNTS NOW LOOK TO BE UNDER AN INCH. ..08..
LONG TERM...SUNDAY THROUGH FRIDAY...
SUNDAY IS THE TAIL END OF THE SHORT TERM STORM SYSTEM...WITH THE
LAST OF THE DEFORMATION ZONE PRECIPITATION EXITING OFF TO THE
NORTHEAST EARLY IN THE DAY. HAVE SOME SLIGHT CHANCE POPS FOR THE
MORNING HOURS WITH RAIN IN THE EAST...WITH MIXED RAIN SNOW ACROSS
THE NORTH.
ON MONDAY ANOTHER SHORTWAVE EJECTS OUT OF THE UPPER LEVEL TROUGH
AXIS AND MOVES NORTHEAST ALONG THE BAROCLINIC ZONE LEFT BEHIND THE
CURRENT STORM SYSTEM. THIS WAVE IS CURRENTLY FORECAST BY MOST OF
THE MODELS TO STAY SOUTHEAST OF THE FORECAST AREA...BUT THE NAM AND
THE 00Z ECMWF BRING IT FAR ENOUGH NORTH TO BRUSH OUR SOUTHEAST WITH
SOME LIGHT PRECIPITATION. HAVE DECIDED TO GO WITH THE DRIER
SOLUTION FOR NOW...BUT WILL HAVE TO RE-EVALUATE LATER AS NEEDED.
TUESDAY...WEDNESDAY AND EARLY THURSDAY APPEAR QUIET FOR NOW...WITH THE
LONGWAVE TROUGH SHIFTING EAST OF THE AREA AND WEAK RIDGING SETTLING
IN. TEMPERATURES WILL REMAIN COLD WITH HIGHS ONLY IN THE MID 20S TO
MID 30S.
THURSDAY NIGHT AND FRIDAY THE LONGWAVE TROUGH DEEPENS ACROSS THE
CONUS AGAIN AND WE HAVE A COLD FRONT DROP THROUGH THE AREA THURSDAY
NIGHT...FOLLOWED BY SOME SNOW. THIS IS A RELATIVELY NEW FEATURE IN
THE MODELS...BUT BOTH THE GFS AND ECMWF ARE SHOWING IT...SO HAVE
RAISED POPS SLIGHTLY ON THURSDAY NIGHT AND FRIDAY WITH SNOW
PRECIPITATION TYPE. TEMPERATURES STILL BELOW NORMAL WITH HIGHS IN
THE 20S AND LOWER 30S. ..LE..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
553 AM CST SAT DEC 3 2011
.AVIATION...
CIGS WILL RANGE FROM IFR TO LOW END MVFR AT KCID/KDBQ WITH VSBYS
1-2SM THROUGH 18Z. VFR CIGS WITH PERHAPS BRIEF 2KFT CIGS WITH
3-5SM CAN BE EXPECTED AT KMLI/KBRL. A DECREASE IN RA INTENSITY IS
EXPECTED 18Z/03-00Z/04 WHICH WILL ALLOW VFR CONDITIONS AT
KMLI/KBRL. KCID/KDBQ WL KEEP 3-5SM WITH CIGS AOB 1KFT AGL. AFT
00Z/04 THE NEXT ROUND OF RA WILL ARRIVE AND DROP VSBYS TO 1-2SM WITH
CIGS AOB 1KFT. KCID/KDBQ MAY SEE A RASN MIX WITH A CHANGE TO ALL
SN AFT 06Z/04.
..08..
&&
.PREV DISCUSSION... /ISSUED 331 AM CST SAT DEC 3 2011/
SYNOPSIS...
06Z SFC ANALYSIS HAD A COLD FRONT FROM THE EASTERN DAKOTAS INTO
CENTRAL NEBRASKA. A LOW WAS IN EASTERN COLORADO WITH A FRONT INTO
SOUTHERN NEBRASKA. RADAR TRENDS SHOW A LARGE SHIELD OF WAA
ASSOCIATED WITH A WAVE FROM WISCONSIN BACK INTO WESTERN MISSOURI.
DEW POINTS WERE IN THE 30S AND 40S ACROSS MUCH OF THE MIDWEST WITH
20S OVER THE UPPER MIDWEST AND GREAT LAKES.
SHORT TERM...TODAY AND TONIGHT...
WAA HAS ALLOWED TEMPERATURES TO RISE AND PUSH WBZ SFC TEMPERATURES
TO ABOVE 34 FOR AREAS SOUTH OF HWY 20. ANY THREAT FOR FZRA OR FZDZ
WILL END BY SUNRISE AS WBZ TEMPERATURES CONTINUE TO RISE.
THE INITIAL WAA PRECIP SHIELD WILL MOVE ACROSS THE AREA DURING THE
MORNING HOURS. BASED ON RADAR AND RUC TRENDS THE OVERALL INTENSITY
OF THE PRECIP SHOULD DECREASE DURING THE MID TO LATE MORNING HOURS.
THE QUESTION THEN TURNS TO PRECIP CHANCES FOR THE AFTERNOON.
ALL MODELS SHOW CONDENSATION PRESSURE DEFICITS INCREASING DURING THE
AFTERNOON HOURS. FORCING WEAKENS AND CONVERGENCE IN THE LOWER LEVELS
EITHER WEAKENS OR IS NOT PRESENT. THUS PRECIP CHANCES WILL BE
GREATLY LOWER FOR MOST AREAS GENERALLY EAST OF A KEOK TO KFEP LINE
FOR MUCH OF THE AFTERNOON. THE POTENTIAL DOES EXIST THAT EASTERN
PARTS OF THE CWFA COULD GO COMPLETELY DRY DURING THE AFTERNOON
HOURS. THIS SCENARIO WILL HAVE TO BE RE-EVALUATED.
TONIGHT...THE MAIN SFC LOW ARRIVES AND BRINGS ANOTHER ROUND OF
PRECIPITATION TO THE AREA. WBZ TEMPERATURES ARE ABOVE 34 DEGREES SO
ALL PRECIPITATION WILL BE IN THE FORM OF RAIN DURING THE EVENING
HOURS. AFTER MIDNIGHT...THE RACE BEGINS WITH THE CAA TO SEE IF THE
PRECIP CAN MIX WITH AND CHANGE OVER TO SNOW PRIOR TO SUNRISE. THE
FAR NORTHWEST PART OF THE CWFA WOULD HAVE THE BEST CHANCE. MORE
INTERESTING IS THE DRY SLOT BEING DEPICTED BY THE MODELS. FORCING ON
THETA SURFACES 290-300K SHOW ALL FORCING ENDING VERY LATE TONIGHT
WHICH IS COINCIDENT WITH THE ARRIVAL OF THE DRY SLOT. THUS THE
POTENTIAL DOES EXIST THAT PRECIP MAY END PRIOR TO THE COLD AIR
ARRIVING. IF THIS WOULD OCCUR...THE POTENTIAL FOR A MIX OR A CHANGE
OVER IN THE NORTHWEST CWFA WOULD BE LOW.
IF THE PRECIPITATION DOES END...THE QUESTION THEN BECOMES WHETHER OR
NOT ANY FZDZ COULD DEVELOP. RIGHT NOW THE FCST SOUNDINGS DO NOT
SUGGEST THIS. THUS THE CURRENT THINKING IS THAT A MIX WILL DEVELOP
IN THE NORTHWEST WITH A QUICK CHANGE OVER BEFORE THE PRECIP ENDS.
AMOUNTS NOW LOOK TO BE UNDER AN INCH. ..08..
LONG TERM...SUNDAY THROUGH FRIDAY...
SUNDAY IS THE TAIL END OF THE SHORT TERM STORM SYSTEM...WITH THE
LAST OF THE DEFORMATION ZONE PRECIPITATION EXITING OFF TO THE
NORTHEAST EARLY IN THE DAY. HAVE SOME SLIGHT CHANCE POPS FOR THE
MORNING HOURS WITH RAIN IN THE EAST...WITH MIXED RAIN SNOW ACROSS
THE NORTH.
ON MONDAY ANOTHER SHORTWAVE EJECTS OUT OF THE UPPER LEVEL TROUGH
AXIS AND MOVES NORTHEAST ALONG THE BAROCLINIC ZONE LEFT BEHIND THE
CURRENT STORM SYSTEM. THIS WAVE IS CURRENTLY FORECAST BY MOST OF
THE MODELS TO STAY SOUTHEAST OF THE FORECAST AREA...BUT THE NAM AND
THE 00Z ECMWF BRING IT FAR ENOUGH NORTH TO BRUSH OUR SOUTHEAST WITH
SOME LIGHT PRECIPITATION. HAVE DECIDED TO GO WITH THE DRIER
SOLUTION FOR NOW...BUT WILL HAVE TO RE-EVALUATE LATER AS NEEDED.
TUESDAY...WEDNESDAY AND EARLY THURSDAY APPEAR QUIET FOR NOW...WITH THE
LONGWAVE TROUGH SHIFTING EAST OF THE AREA AND WEAK RIDGING SETTLING
IN. TEMPERATURES WILL REMAIN COLD WITH HIGHS ONLY IN THE MID 20S TO
MID 30S.
THURSDAY NIGHT AND FRIDAY THE LONGWAVE TROUGH DEEPENS ACROSS THE
CONUS AGAIN AND WE HAVE A COLD FRONT DROP THROUGH THE AREA THURSDAY
NIGHT...FOLLOWED BY SOME SNOW. THIS IS A RELATIVELY NEW FEATURE IN
THE MODELS...BUT BOTH THE GFS AND ECMWF ARE SHOWING IT...SO HAVE
RAISED POPS SLIGHTLY ON THURSDAY NIGHT AND FRIDAY WITH SNOW
PRECIPITATION TYPE. TEMPERATURES STILL BELOW NORMAL WITH HIGHS IN
THE 20S AND LOWER 30S. ..LE..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS GRAY ME
656 AM EST SAT DEC 3 2011
.SYNOPSIS...
HIGH PRESSURE WILL DOMINATE THE WEATHER PATTERN TODAY AND WILL
GRADUALLY SHIFT OFFSHORE BY TOMORROW. SOUTHWEST FLOW BRINGS WARMER
TEMPERATURES FOR SUNDAY AND MONDAY. A WEAK COLD FRONT MOVES INTO
NORTHERN PARTS OF THE AREA ON MONDAY BEFORE STALLING. LOW PRESSURE
TRACKS ALONG THE FRONT ON TUESDAY SPREADING RAIN ACROSS THE
REGION. A COLD FRONT WILL PUSH THROUGH THE AREA ON WEDNESDAY
BRINGING COLDER TEMPERATURES BACK TO THE AREA WITH RAIN CHANGING
TO SNOW BEFORE ENDING.
&&
.NEAR TERM /THROUGH TONIGHT/...
.UPDATE...
CLOUDS HAVE ERODED QUITE A BIT ACROSS THE INTERIOR AND PORTIONS OF
SOUTHERN NH. ADJUSTED CLOUD COVER FOR THIS UPDATE AS WELL AS DEW
POINTS...WITH SOME OF THE HIGHER TERRAIN EXHIBITING SOME VERY DRY
READINGS WHICH THE MODELS DID NOT CAPTURE.
&&
.PREVIOUS DISCUSSION...
STRATUS DECK ASSOCIATED WITH SUBSIDENCE INVERSION HAS BEGUN TO
DIMINISH SLIGHTLY AS LOW LEVEL MOISTURE DECREASES. RUC FORECAST
SOUNDINGS CAPTURE THIS WELL AND SHOW MOISTURE SCATTERING OUT IN THE
NEXT FEW HOURS. CLOUDS WILL LIKELY REMAIN THROUGH DAYBREAK ACROSS
NORTHERN NH AND NORTH CENTRAL MAINE WITH SOME FOG MIXED IN.
ONCE CLOUDS DISAPPEAR TEMPERATURES WILL WARM QUICKLY IN THE DRY
ENVIRONMENT. READINGS WILL TOP OUT NEAR NORMAL VALUES WITH MID TO
UPPER 30S NORTH TO LOWER TO MID 40S SOUTH. IT SHOULD BE A PLEASANT
DAY WITH SUNNY SKIES AND LIGHT WINDS AS HIGH PRESSURE SLOWLY MOVES
OVER THE REGION.
&&
.SHORT TERM /SUNDAY/...
SURFACE HIGH PRESSURE WILL SHIFT OFFSHORE TONIGHT AS UPPER LEVEL
RIDGING BEGINS TO BREAK DOWN. SOUTHERLY FLOW WILL RESULT IN SLIGHTLY
HIGHER TEMPERATURES THAN SATURDAY WITH HIGHS IN THE LOWER 40S NORTH
TO LOWER 50S SOUTH. HIGH CLOUDS WILL BEGIN TO STREAM IN DURING THE
DAY AS THE UPPER LEVEL JET AND MAIN STORM TRACK NEAR...BUT MOST OF
THE DAY SHOULD BE SUNNY TO PARTLY CLOUDY. PRECIPITATION CHANCES WILL
HOLD OFF AS A FRONTAL BOUNDARY STALLS WELL TO OUR NORTHWEST.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
BROAD... PERSISTENT TROUGH STRETCHING FROM HUDSON BAY TO THE
SOUTHWEST DESERTS WILL BE THE DRIVING FORCE FOR WEATHER FEATURES
ACROSS THE CONTINENT THROUGH NEXT WEEK.
MINOR SHORTWAVE TROUGH CROSSES THROUGH QUEBEC ON SUNDAY NIGHT...
WITH A WEAK SURFACE LOW AND COLD FRONT ACCOMPANYING IT. THIS FRONT
MAY MAKE IT DOWN INTO THE NORTHERN PART OF MAINE AND NEW
HAMPSHIRE... BUT MOST OF THE ENERGY WILL BE TO THE NORTH. RAIN
CHANCES WILL BE LIMITED TO THE MOUNTAINS. SOUTHWEST FLOW AROUND
THE TROUGH AND AROUND THE BACK SIDE OF THE DEPARTING SURFACE HIGH
WILL ADVECT WARMER AIR INTO NORTHERN NEW ENGLAND. EXPECT HIGHS IN
THE 50S WIDESPREAD ESPECIALLY MONDAY AND TUESDAY.
ANOTHER WEAK WAVE CROSSES THROUGH THE SOUTHWESTERLY JET AND OVER
NORTHERN NEW ENGLAND ON TUESDAY WITH MORE WIDESPREAD LIGHT RAIN
EXPECTED. ONSHORE SOUTHERLY FLOW WILL AID IN MOISTURE TRANSPORT
AND ADD OROGRAPHIC LIFT TO INCREASE PRECIPITATION CHANCES.
MODELS DIVERGE ON HOW TO HANDLE THE FINAL PIECE OF THE LARGE SCALE
TROUGH THAT DIGS THROUGH THE SOUTHERN PLAINS ON TUESDAY. GFS IS
MORE PROGRESSIVE... WITH THE ENTIRE TROUGH AXIS SHIFTING EASTWARD
ON WEDNESDAY AND A SURFACE LOW STRENGTHENING RAPIDLY OVER NEW
ENGLAND. UNDER THIS SCENARIO... COLD AIR WILL REMAIN TO THE
NORTHWEST AND PRECIPITATION WILL BE MOSTLY RAIN BEFORE THE TROUGH
AXIS AND SURFACE FRONT PUSH THROUGH ON WEDNESDAY... CHANGING RAIN
TO SNOW BEFORE ENDING. HOWEVER... THE ECMWF ONLY EJECTS A PIECE OF
THE ENERGY FROM THE MAIN TROUGH AXIS ON WEDNESDAY... RESULTING IN
LESS EXTREME SURFACE FEATURES OVER OUR REGION... AND A MORE
QUICKLY ADVANCING COLD FRONT. THE MAIN TROUGH FINALLY CROSSES OUR
AREA ON THURSDAY WITH A SURFACE LOW WELL OFFSHORE AND SNOW MAINLY
OVER SOUTHERN AND CENTRAL NEW ENGLAND. HAVE GONE MAINLY WITH THE
GFS SOLUTION WITH THIS FORECAST AS IT IS MORE CONSISTENT WITH
PRIOR RUNS... BUT THERE IS SOME MERIT TO THE ECMWF SCENARIO AS
TROUGHS WHICH DIG THAT FAR SOUTH TEND TO SLOW DOWN AND TAKE LONGER
TO FINALLY GET PUSHED EASTWARD IN THE FLOW.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
SHORT TERM...BRIEF MVFR CONDITIONS POSSIBLE UNTIL SUNRISE...
OTHERWISE VFR CONDITIONS AND LIGHT WINDS WILL PREVAIL THROUGH
TONIGHT.
LONG TERM...VFR THROUGH MONDAY. MAY SEE IFR CEILINGS AND RAIN
DEVELOPING TUESDAY.
&&
.MARINE...
SHORT TERM...SCA FOR SEAS OF 5 FT OR HIGHER WILL CONTINUE THROUGH
5 PM.
LONG TERM...SOUTHWEST FLOW PERSISTS AROUND DEPARTING HIGH
PRESSURE. FLOW WILL STRENGTHEN AS FRONT AND UPPER TROUGH APPROACH
FOR WEDNESDAY. SEAS GENERALLY HOVERING RIGHT AROUND THE 5 FT
THRESHOLD TUESDAY ONWARD.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 5 PM EST THIS
AFTERNOON FOR ANZ150-152-154.
&&
$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...
MARINE...
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
547 AM CST SAT DEC 3 2011
.SHORT TERM...TODAY THROUGH MONDAY NIGHT
343 AM CST SAT DEC 3 2011
MAIN FORECAST CONCERN IS ON MIXED PRECIPITATION THROUGH
TONIGHT...ALONG WITH SNOWFALL AMOUNTS.
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND 500MB HEIGHT ANALYSIS
SHOWED RIDGING OVER THE EAST PACIFIC...SPLIT TROUGHING FROM
MANITOBA SOUTHWEST INTO ARIZONA...AND BUILDING RIDGING FROM THE
SOUTHEASTERN U.S. INTO THE GREAT LAKES REGION. WITHIN THE SPLIT
TROUGHING...A POTENT SHORTWAVE WAS NOTED OVER SOUTHWEST NEW MEXICO
WITH A NICE BAROCLINIC LEAF ON WATER VAPOR NORTHEAST OF IT. 850MB
WINDS FAIRLY STRONG AHEAD OF THE SPLIT TROUGHING...RANGING FROM
40-60 KNOTS OUT OF THE SOUTH-SOUTHWEST FROM TEXAS INTO KANSAS AND
NORTHEAST INTO THE FORECAST AREA. THESE WINDS HAVE BEEN RAPIDLY
ADVECTING WARMER AIR AND MOISTURE NORTHWARD...CAUSING RAIN TO
BREAK OUT ACROSS IOWA...FAR SOUTHEASTERN MINNESOTA AND MUCH OF
WISCONSIN EXCLUDING THE NORTHWEST PART. 08Z PRECIPITABLE WATER
ANALYSIS FROM THE RUC SHOWS VALUES OF 0.75 TO 0.9 INCHES IN THE
SOUTHERN PORTION OF THE FORECAST AREA...OR ABOUT 200 PERCENT ABOVE
NORMAL. 2 METER AIR TEMPERATURES HAVE CLIMBED TO AT OR ABOVE 32F
AT MOST LOCATIONS AND DEWPOINTS ARE ALMOST THE SAME NOW. THIS
SHOULD BE REDUCING THE FREEZING OF THE RAIN AT THE SURFACE.
TODAY AND TONIGHT...SHORTWAVE OVER NEW MEXICO IS FORECAST TO
GRADUALLY ACCELERATE TO THE NORTHEAST DURING THIS PERIOD AS
A POTENT SHORTWAVE DROPS DOWN INTO MONTANA. INITIAL ISENTROPIC
LIFTING TAKING PLACE TO PRODUCE CURRENT PRECIPITATION SHOULD HOLD
FAIRLY STEADY THROUGH THE MORNING. WITH WARM ADVECTION OCCURRING...
ANY FREEZING OF THE PRECIPITATION SHOULD BE LIMITED TO BEFORE
13Z...THEN RAIN/DRIZZLE IS ANTICIPATED. DURING THE AFTERNOON...LOW
TO MID-LEVEL FRONTOGENESIS WILL INTENSIFY OVER THE SOUTHWEST
PORTION OF THE FORECAST AREA...SPREADING NORTHEAST DURING THE
EVENING. THIS FRONTOGENESIS IS CAUSED BY A COMBINATION FROM THE
DPVA PRODUCED AHEAD OF THE APPROACHING NEW MEXICO SHORTWAVE...AS
WELL AS A NEAR COUPLED UPPER JET STRUCTURE DEVELOPING. IN
ADDITION...CROSS-SECTIONS INDICATE THE PRESENCE OF SOME NEGATIVE
EPV ON TOP OF THE FRONTOGENESIS ZONE...ALLOWING FOR POTENTIAL FOR
A FEW CONVECTIVE ELEMENTS. WITH PRECIPITABLE WATER VALUES HOLDING
FAIRLY STEADY INTO THE EVENING...NEEDLESS TO SAY THE LATE
AFTERNOON INTO THE EVENING PERIOD IS OF MOST CONCERN FOR HEAVIEST
PRECIPITATION. GIVEN THE HIGHER PRECIPITATION RATES ALLOWING FOR
DIABATIC COOLING AND THE SURFACE FLOW TURNING NORTHERLY TO ALLOW FOR
COLD ADVECTION...THE AFTERNOON AND EVENING PRECIPITATION SHOULD
GRADUALLY CHANGE OVER TO SNOW...QUICKEST OVER THE NORTHWEST HALF
OF THE FORECAST AREA. 03.00Z MODEL QPF SPREADS ARE SOMEWHAT
HIGH...RANGING FROM 0.20-0.60 INCHES FOR 18-06Z. STILL...WITH SNOW
TO WATER RATIOS LIKELY TO STAY AROUND A 10 TO 1 AVERAGE GIVEN DEEP
AGGREGATION LAYER NOTED ON SOUNDINGS...LIKELY TO END UP WITH
SNOWFALL AMOUNTS IN THIS TIME WINDOW AT MOST UP TO 5 INCHES. SINCE
THIS IS AN INCH BELOW WARNING CRITERIA...AND MODELS TOO COLD
RIGHT NOW WITH HOURLY TEMPERATURES SUGGESTING PRECIPITATION COULD
END UP BEING EVEN MORE RAIN FOR THE AFTERNOON...AN ADVISORY SEEMS
TO BE THE BETTER REPLACEMENT FOR THE WATCH RIGHT NOW. DURING THE
OVERNIGHT HOURS...THE PRECIPITATION SHOULD SLOWLY START LIFTING TO
THE NORTHEAST WITH THE SHORTWAVE. HOWEVER...PLENTY OF LOW LEVEL
STILL EXISTS. THIS BRINGS UP A CONCERN...AS ONCE THE SHORTWAVE
MOVES IN THE ICE MAY SCOUR OUT...RESULTING IN RAIN/FREEZING RAIN.
THE BEST CHANCE FOR THIS TO OCCUR IS EAST OF A LINE FROM CHARLES
CITY IOWA TO LA CROSSE AND WISCONSIN RAPIDS. DID PUT IN A FEW
HUNDREDTHS OF ICE ACCUMULATION NEAR THIS LINE. WITH THE ICE
ACCUMULATION AND TO ADD A BUFFER IN CASE THE PRECIPITATION CHANGES
TO SNOW QUICKER TONIGHT...ADDED ANOTHER ROW OF COUNTIES JUST EAST
OF THE PREVIOUS WATCH FOR AN ADVISORY. REGARDING TEMPERATURES...
INCREASED THEM BOTH TODAY AND TONIGHT GIVEN CURRENT WARMER TRENDS.
SUNDAY THROUGH MONDAY NIGHT...MUCH QUIETER TIME PERIOD. SHORTWAVE
TROUGHING DIGGING INTO MONTANA TONIGHT IS FORECAST BY ALL MODELS
TO MARCH SLOWLY EAST...REACHING THE WESTERN END OF THE FORECAST
AREA AROUND 12Z TUESDAY. ALTHOUGH THE FORECAST AREA RESIDES IN
SOUTHWEST FLOW ALOFT...ALL OF THE SHORTWAVES IN THAT SOUTHWEST
FLOW TO HELP PRODUCE PRECIPITATION LOOK TO STAY TO THE SOUTHEAST
OF HERE. IN ADDITION...THE SHORTWAVE MOVING THROUGH TONIGHT HELPS
TO SCOUR OUT MUCH OF THE MOISTURE...NOTED BY PRECIPITABLE WATER
VALUES FALLING TO 0.25 INCH OR LESS BY 21Z SUNDAY. DID MAINTAIN
SOME LOW 20-30 PERCENT CHANCES FOR THE EASTERN TWO THIRDS OF THE
FORECAST AREA ON SUNDAY...DUE TO LINGERING LOW LEVEL LIFT.
AGAIN...THE PRESENCE OF ICE IS QUESTIONABLE...ESPECIALLY OVER
NORTHEAST IOWA AND SOUTHWEST WISCONSIN. AS A RESULT...HAVE
MENTIONED A SNOW/FREEZING DRIZZLE MIX. AFTER THAT...DRY WEATHER
WILL BE THE RULE...WITH ONLY SOME INCREASE OF MID/HIGH CLOUDS AS
THE MONTANA SHORTWAVE TROUGHING APPROACHES. BIGGER IMPACT
TEMPERATURES. 850MB TEMPS AT 12Z SUNDAY SHOULD RANGE FROM -4C EAST
TO -8C WEST. THESE COOL THROUGH THE DAY SUNDAY...SO HIGHS SHOULD
END UP CLOSE TO THE MORNING LOWS. FURTHER COOLING OF 850MB TEMPS
IS PROGGED FOR MONDAY...DROPPING TO -10 TO -14C. THEREFORE...
HIGHS IN MOST LOCATIONS LOOK TO ONLY TOP OUT IN THE 20S. MORE
TEENS AND SINGLE DIGIT READINGS ABOVE ZERO EXPECTED AT NIGHT WITH
NOCTURNAL COOLING.
.LONG TERM...TUESDAY THROUGH FRIDAY NIGHT
343 AM CST SAT DEC 3 2011
03.00Z ECMWF/GFS/CANADIAN AND GFS ENSEMBLES CONTINUE TO PAINT A
COLDER THAN NORMAL PATTERN FOR THE FORECAST AREA AS A POLAR VORTEX
SETS UP OVER HUDSON BAY BY LATE IN THE WEEK. SHORTWAVE TROUGH WILL
MOVE EAST TO WEST ACROSS THE AREA ON TUESDAY...NOT REALLY BRINGING
ANY PRECIPITATION WITH IT DUE TO LACK OF MOISTURE. HOWEVER...850MB
TEMPS FALL FURTHER...DOWN TO -11 TO -15C. BRIEF WARMING SHOULD OCCUR
TUESDAY NIGHT AS A WEAK UPPER RIDGE CROSSES IN THE WAKE OF TUESDAYS
SHORTWAVE TROUGH. THEN THIS GETS REPLACE BY A ZONAL FLOW FOR
WEDNESDAY INTO THURSDAY IN RESPONSE TO A SERIES OF SHORTWAVES
CROSSING SOUTHERN CANADA. THIS FLOW SETUP SHOULD ALLOW FOR DRY BUT
COOL CONDITIONS TO CONTINUE. ALL MODELS THEN INDICATE A DEEP
TROUGH DROPPING SOUTH THROUGH THE NORTHERN PLAINS THURSDAY NIGHT.
AHEAD OF THIS TROUGH...SOME PRECIP COULD OCCUR DUE TO DPVA AND
ISENTROPIC LIFT...THOUGH MOISTURE AGAIN IS QUESTIONABLE. INCLUDED
A 20 PERCENT CHANCE OF SNOW ACROSS THE SOUTHERN PORTIONS OF THE
FORECAST AREA...IN-LINE WITH THE 03.00Z GFS/ECMWF. THE UPPER
TROUGHING MOVES INTO THE AREA ON FRIDAY...BRINGING AIR MORE OF
ARCTIC ORIGIN ACROSS WITH 850MB TEMPS TANKING TO AROUND -20C. FOR
NOW FOLLOWED A CONSENSUS OF GUIDANCE FOR HIGHS AND LOWS THROUGHOUT
THE LONG TERM FORECAST...BUT MAY NEED TO LOWER HIGHS/LOWS FOR
FRIDAY AND FRIDAY NIGHT IF THIS -20C AT 850MB AIRMASS FORECAST
PERSISTS.
&&
.AVIATION...TODAY AND TONIGHT
547 AM CST SAT DEC 3 2011
A SIGNIFICANT WINTER STORM WILL IMPACT THE TAF SITES WITH MVFR/IFR
CIGS/VSBYS MUCH OF TODAY/TONIGHT...WITH CONDITIONS IMPROVING TO
MVFR/VFR ON SUNDAY. THE TAF SITES WILL SEE A BREAK FROM MUCH OF THE
PRECIP THIS MORNING HOWEVER IFR/MVFR CIGS AND SOME MVFR VSBYS IN BR
WILL REMAIN ACROSS THE AREA. AS THE LOW LIFTS TOWARD THE UPPER
MIDWEST THIS AFTERNOON...PRECIP WILL INCREASE/SPREAD ACROSS THE TAF
SITES... MAINLY -RA AT KLSE AND A -RA/-SN MIX AT KRST. COLDER AIR
WILL SPREAD IN DURING THE AFTERNOON AND EARLY EVENING...CHANGING THE
MIX TO ALL SNOW AT KRST DURING THE MID AFTERNOON AND AROUND 00Z AT
KLSE. THE STRONGEST OF THE FORCING/LIFT WITH THE STORM SYSTEM WILL
MOVE ACROSS THE TAF SITES THIS EVENING...WITH A 4 TO 6 HR PERIOD OF
IFR TO LIFR CIGS/VSBYS IN SNOW EXPECTED. SNOWFALL IS EXPECTED TO
IMPACT AIRPORT OPS AT BOTH KRST/KLSE WITH 3 TO 6 INCHES AT KRST AND
1 TO 3 INCHES AT KLSE. AS THE LOW MOVES EAST OF THE AREA LATER
TONIGHT AND THE LIFT GRADUALLY WEAKENS CIGS/VSBYS EXPECTED TO
IMPROVE AS THE -SN TAPERS OFF/ENDS AND DRIER AIR STARTS TO MOVE IN
FROM THE NORTHWEST. WITH LOSS OF ICE IN THE CLOUDS LATER TONIGHT...
KLSE MAY SEE SOME FZDZ BEFORE THE PRECIP ENDS LATE TONIGHT. LEFT
THIS OUT OF THE KLSE TAF FOR NOW GIVEN LESSER CONFIDENCE IN THE
DETAILS FOR LATE TONIGHT.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
343 AM CST SAT DEC 3 2011
WI...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 AM CST
SUNDAY FOR WIZ041>044-053.
FREEZING RAIN ADVISORY UNTIL 7 AM CST THIS MORNING FOR WIZ029-
032>034-041>044-053>055-061.
WINTER WEATHER ADVISORY FROM NOON TODAY TO 6 AM CST SUNDAY FOR
WIZ017-029-032>034.
MN...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 AM CST
SUNDAY FOR MNZ096.
FREEZING RAIN ADVISORY UNTIL 7 AM CST THIS MORNING FOR MNZ079-
086>088-094>096.
WINTER WEATHER ADVISORY FROM NOON TODAY TO 6 AM CST SUNDAY FOR
MNZ079-086>088-094-095.
IA...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 AM CST
SUNDAY FOR IAZ010-011-019-029.
FREEZING RAIN ADVISORY UNTIL 7 AM CST THIS MORNING FOR
IAZ008>011-018-019-029-030.
WINTER WEATHER ADVISORY FROM NOON TODAY TO 6 AM CST SUNDAY FOR
IAZ008-009-018.
&&
$$
SHORT TERM...AJ
LONG TERM....AJ
AVIATION.....RRS
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
316 AM MST SAT DEC 3 2011
.SHORT TERM...TODAY THROUGH MONDAY...RELATIVELY ACTIVE IN THE
SHORT TERM THIS WEEKEND AND INTO EARLY NEXT WEEK WITH SEVERAL
IMPACTS ACROSS SOUTHEAST WYOMING AND PORTIONS OF WESTERN NEBRASKA.
SNOW EARLY THIS MORNING IS STARTING TO TAPER OFF TO LIGHT FLURRIES
WEST OF THE LARAMIE RANGE WITH VISIBILITIES AT RAWLINS AND
ARLINGTON INCREASING AT 2 AM. MOST OF THE LARAMIE VALLEY STRUGGLED
WITH PERSISTENT SNOWFALL LAST NIGHT...DUE TO A SNOW SHADOW EFFECT
OFF THE LARAMIE RANGE AND AN EASTERLY WIND. THEREFORE...CANCELLED
THE WINTER STORM WARNING FOR I-80 BETWEEN LARAMIE AND RAWLINS
INCLUDING THE SNOWY RANGE AND REPLACED IT WITH A WINTER WEATHER
ADVISORY UNTIL 6 AM. SNOTEL OBSERVATIONS SHOW MAINLY BETWEEN 4 TO 8
INCHES OF SNOWFALL IN THE SOUTHERN LARAMIE RANGE AND SNOWY RANGE
WITH SNOWFALL RATES BECOMING MUCH LIGHTER EARLY THIS MORNING.
GUSTY WINDS WERE ALSO NOT MUCH OF A FACTOR WITH A FEW LOCALIZED
AREAS REPORTING GUSTS UP TO 25 MPH AT TIMES. IF CURRENT TRENDS
CONTINUE...MAY NEED TO CANCEL MOST OF THE WINTER WEATHER ADVISORY
BY SUNRISE WITH KCYS RADAR LOOP SHOWING A GRADUAL LOWERING OF
REFLECTIVITY. IT APPEARS THE CHEYENNE AREA DID BETTER THAN
PREVIOUSLY EXPECTED WITH REPORTS OF 4 INCHES OF SNOW AROUND THE
AREA AT 2 AM. IR SATELLITE LOOP CONTINUES TO SHOW COOLER CLOUD
TOPS ACROSS EXTREME SOUTHEAST WYOMING AND SOUTHWEST NEBRASKA...SO
EXPECT PERIODS OF LIGHT SNOW TO CONTINUE EAST OF THE SOUTHERN
LARAMIE RANGE. SNOW WILL CONTINUE TO TAPER OFF ELSEWHERE THIS
MORNING WITH LITTLE ADDITIONAL ACCUMULATION. TEMPERATURES TODAY
WILL BE MUCH COLDER COMPARED TO YESTERDAY...WITH HIGHS STRUGGLING
TO REACH THE LOW TO MIDDLE 20S. EVEN COLDER TEMPERATURES ARE
EXPECTED BY SUNDAY AND MONDAY.
MODELS SHOW THE NEXT COLD FRONT WITH MODIFIED ARCTIC AIR PUSHING
SOUTHWARD INTO THE FORECAST AREA ON SUNDAY. LOW TEMPERATURES
SUNDAY MORNING WITH BE QUITE COLD AND IN THE SINGLE DIGITS OVER
THE HIGH PLAINS AND ZERO TO 10 BELOW ZERO WEST OF THE LARAMIE
RANGE. WINDS WILL INCREASE SLIGHTLY AHEAD OF THIS NEXT COLD
FRONT...WITH BITTERLY COLD WIND CHILL TEMPERATURES POSSIBLE ACROSS
SOUTHEAST WYOMING AS SOME AREAS DROP TO -20. THIS FRONT WILL
QUICKLY MOVE SOUTHWARD ACROSS THE AREA AND INTO COLORADO THROUGH
THE DAY ON SUNDAY...WITH ANOTHER CHANCE OF LIGHT SNOW AND
TEMPERATURES LIKELY LOWERING INTO THE SINGLE DIGITS IN THE
AFTERNOON AFTER MORNING HIGHS IN THE TEENS AND 20S. ANOTHER ONE TO
THREE INCHES OF SNOW IS POSSIBLE MAINLY ACROSS SOUTHEAST
WYOMING...BUT DO NOT EXPECT MODERATE OR SIGNIFICANT ACCUMULATIONS
SINCE THE AIR WILL BE VERY COLD AND WILL NOT CONTAIN MUCH
MOISTURE. TEMPERATURES SUNDAY NIGHT AND MONDAY WILL BE VERY
COLD...WITH LOWS LIKELY BELOW ZERO ACROSS THE MAJORITY OF THE
FORECAST AREA FROM RAWLINS EASTWARD TO THE PANHANDLE OF NEBRASKA.
HIGH TEMPERATURES ON MONDAY WILL STRUGGLE TO REACH THE MIDDLE
TEENS WITH 700MB TEMPERATURES BELOW -20C THROUGH THE DAY. ONE
POSSIBLE CONCERN IS SUNDAY NIGHT WITH MODELS SHOWING A BRISK
NORTHERLY WIND BETWEEN 10 TO 20 MPH. THIS MAY RESULT IN WIND
CHILLS VALUES AROUND -30 WHICH MEET WIND CHILL WARNING CRITERIA.
MONDAY WILL BE DRIER...SO LOWERED POP BELOW 10 PERCENT DURING THE
DAY.
.LONG TERM...MONDAY NIGHT THROUGH SATURDAY...00Z ECMWF/00Z GFS/GEFS
CONSENSUS MAINTAINS A HIGHLY AMPLIFIED MID/UPPER LEVEL PATTERN OVER
NORTH AMERICA THROUGH THE PERIOD. THE MAIN FEATURES WILL BE RIDGES
ANCHORED OVER THE NORTH ATLANTIC AND NORTHEAST PACIFIC...WITH A MEAN
LONG WAVE TROUGH ENCOMPASSING MOST OF THE LOWER 48 STATES. ONE
SHORT WAVE TROUGH WILL BE MOVING EAST THROUGH THE PLAINS AND MIDWEST
ON TUESDAY...REPLACED BY A NORTHEAST-SOUTHWEST SHORT WAVE RIDGE AXIS
PASSING SOUTHEAST ACROSS THE CWA TUESDAY NIGHT. A RATHER DEEP VORTEX
THEN TAKES RESIDENCE NEAR HUDSON BAY CANADA WITH A TROUGH AXIS
EXTENDING THROUGH THE CENTRAL AND SOUTHERN ROCKIES THURSDAY...AND
PLAINS ON FRIDAY. AFTER A VERY COLD MONDAY NIGHT/TUESDAY MORNING
WITH LOWS FROM 5 ABOVE TO 15 BELOW...SURFACE HIGH PRESSURE WILL
BECOME CENTERED WEST OF THE CONTINENTAL DIVIDE...WITH A LEE TROUGH
DEVELOPING ALONG THE FRONT RANGE TUESDAY. THIS TROUGH WILL MOVE
EAST INTO THE CENTRAL HIGH PLAINS ON WEDNESDAY...WITH A CANADIAN
COLD FRONT APPROACHING FROM THE NORTH. IT WILL BE MILDER AND BREEZY
BOTH DAYS DUE TO DOWNSLOPING FLOW OFF THE LARAMIE RANGE. HIGHS IN
THE 20S AND 30S TUESDAY WILL RISE INTO THE 30S AND 40S ON WEDNESDAY.
THE COLD FRONT WILL SINK SOUTH THROUGH THE CWA ON THURSDAY WITH
SOME LIGHT SNOW DEVELOPING. THE AIRMASS BEHIND THIS FRONT WILL BE
MODIFIED CONTINENTAL ARCTIC...SO TEMPERATURES WILL NOT BE AS COLD.
THE SNOW WILL END BY FRIDAY MORNING AS HIGH PRESSURE BUILDS SOUTH
INTO THE NORTH CENTRAL ROCKIES AND HIGH PLAINS. BELOW NORMAL
TEMPERATURES FRIDAY WILL MODERATE TO NEAR NORMAL SATURDAY AS LEE
TROUGHING DEVELOPS EAST OF THE LARAMIE RANGE WITH BREEZY DOWNSLOPING
WINDS.
&&
.AVIATION...06Z TAF ISSUANCE...IFR/LIFR CONDITIONS TO CONTINUE
OVERNIGHT WITH LIGHT SNOW. SNOW WILL COME TO AN END BY MID MORNING.
LATEST HRRR GUIDANCE KEEPS IFR GOING FOR OUR WYOMING AIRPORTS
THROUGH 15Z OR SO WITH THE NORTHERN PANHANDLE STAYING VFR.
&&
.FIRE WEATHER...NO FIRE WEATHER CONCERNS THIS WEEKEND AND EARLY
NEXT WEEK. SEVERAL STRONG COLD FRONTS WILL PUSH ACROSS THE AREA
RESULTING IN PERIODS OF LIGHT SNOW AND VERY COLD TEMPERATURES.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER WEATHER ADVISORY UNTIL 6 AM SATURDAY FOR WYZ103-WYZ104-
WYZ105-WYZ106-WYZ107-WYZ109-WYZ111-WYZ112-WYZ113.
WINTER WEATHER ADVISORY UNTIL 2 PM SATURDAY FOR WYZ110-WYZ114-
WYZ115-WYZ116-WYZ117-WYZ118.
NE...NONE.
&&
$$
SHORT TERM/FIRE WEATHER...TJT
LONG TERM/AVIATION...MAJ
AREA FORECAST DISCUSSION
NWS DENVER CO
1005 AM MST SAT DEC 3 2011
.UPDATE...RADAR...WEB CAMS AND REPORTS FROM NORTHERN PLAINS
INDICATING SNOW IS DECREASING...OR ENDED IN SPOTS...FROM NORTH TO
SOUTH. STILL SOME AREAS OF MODERATE SNOW INDICATED ON RADAR...AND
THESE AREAS HAVE SHOWN SIGNS OF DECREASING. OVERALL...CURRENT
FORECAST OF DECREASING SNOW ALONG URBAN CORRIDOR AND FOOTHILLS
STILL ON TRACK. WILL BE LETTING THE ADVISORY FOR THOSE AREAS
EXPIRING AT 18Z AND LEAVING THE OTHER ADVISORY GOING TO 21Z. JUST
SOME MINOR TWEAKS WITH REST OF THE GRIDS THIS AFTERNOON.
&&
.AVIATION...CURRENT TAF TRENDS OF GRADUALLY IMPROVING CONDITIONS
FOR THIS AFTERNOON LOOKING ON TRACK. NORTHERLY WINDS TO BE
DIMINISHING BY 21Z...COULD SEE SOME BLOWING SNOW UNTIL THEN AND
WILL LEAVE IN THE TEMPO GROUP.
&&
.PREV DISCUSSION... /ISSUED 358 AM MST SAT DEC 3 2011/
UPDATE...AFTER FURTHER REVIEW I DECIDED TO INCLUDED ZNES 39 AND
40 IN THE WINTER WEATHER ADVISORY THROUGH 11 AM. ALTHOUGH THE SNOW
AMOUNTS WILL BE ON THE LOW SIDE OF THE ADVISY CRITERIA...BUT WIND
MAY COMPOUND THE PROBLEM FOR A TIME. HEAVIEST BAND OF SNOW APPEARS
TO BE FORMING JUST TO THE EAST OF D.I.A. AT THIS TIME. HRRR STILL
SHOWS THE HEAVIEST PCPN EVENTUALLY SHIFTING TO THE PALMER DIVIDE
AREA AFTER 15Z.
SHORT TERM...
PREV DISCUSSION... /ISSUED 310 AM MST SAT DEC 3 2011/
SHORT TERM...STORM SYSTEM MOVING OVER THE REGION THIS MORNING.
SOME BANDED SNOWFALL HAD OCCURRED OVERNIGHT BUT NOT MUCH BANDED
ENHANCEMENT EVIDENT AT THIS TIME. MDLS INDICATE THE WEAK TO MDT QG
ASCENT AT THE SFC AND ALOFT WILL OCCUR PRIOR TO 18Z. WL CONTINUE
WITH THE CURRENT HIGHLIGHTS. SFC WINDS THIS MORNING HAVE BEEN NORTH
TO NORTHWESTERLY PRIMARILY. WITH THIS IN MIND...BEST AREAS FOR
SNOWFALL THIS MORNING WILL BE ALONG THE PALMER DIVIDE. AREAS OF
BLOWING SNOW MAY ALSO BE AN ISSUE OVER THE NORTHEAST PLAINS. IF
GUSTY WINDS OCCUR ALONG THE URBAN CORRIDOR IT WILL LIKELY BE ALONG
THE CHEYENNE RIDGE AND EAST OF INTERSTATE 25 FOR THE MOST PART. A
DRIER NORTHWESTERLY FLOW ALOFT WILL BE OVER THE CWFA TONIGHT.
CLEARING SKIES WILL ALLOW FOR OVERNIGHT LOWS TO DROP TO THE SINGLE
DIGITS.
LONG TERM...ANOTHER SHORT WAVE AND COLD FRONT WILL DROP SOUTH
ACROSS THE ROCKIES ON SUNDAY. THE WAVE WILL ENTER MONTANA SUNDAY
MORNING AND THEN DIVE SOUTH AND CLOSE OFF OVER THE FOUR CORNERS
SUNDAY NIGHT. THE COLD FRONT WILL MOVE THROUGH NORTHEAST COLORADO
AROUND MID DAY SUNDAY. BEST LIFT ASSOCIATED WITH THIS SYSTEM WILL BE
OVER WESTERN AND CENTRAL COLORADO. THERE WILL BE SOME WEAK UPSLOPE
BEHIND THE FRONT. THE HEAVIEST SNOW WILL FALL OVER THE MOUNTAINS AND
FOOTHILLS WITH JUST LIGHT AMOUNTS ALONG THE FRONT RANGE. THE EASTERN
PLAINS MAY EVEN MISS OUT.
AIRMASS BEHIND THE FRONT WILL BE COLD. TEMPERATURES AT 700MB BOTTOM
OUT AT -20C MONDAY MORNING. STRONG SURFACE HIGH...ABOUT 1040MB...
WILL SETTLE OVER THE AREA MONDAY. THIS WILL BRING CLEAR AND COLD
CONDITIONS MONDAY. MOST LOCATIONS WILL REMAIN IN THE TEENS DURING
THE DAY. MONDAY NIGHT WILL BE COLD WITH SOME LOCATIONS FALLING BELOW
ZERO FOR THE FIRST TIME THIS YEAR. DOWNSLOPE WINDS IN AND NEAR THE
FOOTHILLS WILL DEVELOP MONDAY NIGHT LEADING TO WARMING TEMPERATURES
DURING THE NIGHT.
TUESDAY AND WEDNESDAY WILL BE DRY AND COOL AS A WEAK RIDGE MOVES
ACROSS THE REGION. TEMPERATURES WILL WARM BUT REMAIN BELOW NORMAL
WITH HIGHS IN THE 30S TO MID 40S OVER NORTHEAST COLORADO. ANOTHER
TROUGH AND COLD FRONT WILL DROP SOUTH ACROSS THE STATE THURSDAY.
THIS WILL BRINGING COOLER AIR AND A CHANCE OF SNOW FOR THURSDAY AND
FRIDAY. THIS WILL BE MORE OF A GLANCING BELOW THAN THE PREVIOUS
SYSTEM. SO IT SHOULD NOT BE AS COLD AND IF IT SNOWS...SNOW AMOUNTS
WILL BE ON THE LOW SIDE.
AVIATION...NOT MUCH ADJUSTMENTS PLANNED TO THE ONGOING FORECASTS.
SFC VSBYS WILL GENERALLY HOVER BETWEEN 1-2 MILES THIS MORNING...WITH
THE CIGS LESS THAN 2K FT AGL...AND OCCASIONAL VSBYS LESS THAN 1 MILE
AND CIGS LESS THAN 1K FT. GUSTY NORTH TO NORTHWEST WINDS ARE STILL
POSSIBLE BETWEEN 12-18Z. CONDITIONS SHOULD GRADUALLY IMPROVE FM THE
NORTH AND WEST AFTER 18Z. LOWER VSBYS/CIGS WILL LINGER LONGEST OVER
CENTENNIEL AIRPORT WITH GRADUAL IMPROVEMENT THERE AFTER 21Z..
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 2 PM MST THIS AFTERNOON FOR COZ041-
045-046-049.
WINTER WEATHER ADVISORY UNTIL 11 AM MST THIS MORNING FOR COZ035-
036-038>040.
&&
$$
SHORT TERM...D-L
LONG TERM....MEIER
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
308 PM CST SAT DEC 3 2011
.SYNOPSIS...
MAIN FEATURE OF INTEREST IS THE UPPER LEVEL LOW OVER LAS VEGAS WITH
A LEAD WAVE EJECTING OVER WESTERN KANSAS AT 18Z. MEANWHILE...
SURFACE LOW IS LOCATED IN SOUTH-CENTRAL KANSAS WITH THE COLD FRONT
EXTENDING NORTH TO FORT DODGE /KFOD/ AND THE UPPER PENINSULA. TEMPS
BEHIND THE FRONT DIVE FROM THE MID AND SOME UPPER 40S INTO THE LOWER
30S. LARGE AREA OF RAIN IN THE WARM SECTOR LIFTED NORTH TODAY WITH
PRECIP AMOUNTS TYPICALLY IN THE ONE HALF TO ONE INCH RANGE. NEXT
ROUND OF PRECIP ASSOCIATED WITH THE MAIN COLD FRONT NOW SPANNING
CENTRAL IOWA AND MUCH OF MISSOURI.
&&
.SHORT TERM...TONIGHT AND SUNDAY...
MAIN FORECAST CONCERN TONIGHT IS THE BEHAVIOR OF THE NEXT ROUND OF
PRECIP. RUC BRINGS THE SURFACE LOW OVER VINTON /KVTI/ BY 03Z THIS
EVENING. THIS IS SLIGHTLY FASTER AND FARTHER NORTHWEST THAN MODEL
FORECASTS HAD BEEN BUT IS IN LINE WITH THE OVERALL TREND TO A WARMER
FORECAST. IN TERMS OF PRECIP...THIS MORE WESTERN TRACK...AS SEEN IN
THE RUC AND CURRENT RADAR TRENDS...SUGGESTS RAIN THROUGH THE EVENING
WITH ONLY A BRIEF CHANGE TO SNOW IN THE FAR NORTHERN COUNTIES BEFORE
PRECIP ENDS LATE TONIGHT/EARLY SUNDAY MORNING. MUCH OF THE AREA TO
BE DRY-SLOTTED OVERNIGHT WITH ONLY THE NORTHERN AND WESTERN SECTIONS
EXPECTED TO SEE WRAP-AROUND PRECIP AS THE LOW RACES OFF TO THE
NORTHEAST. EVEN SO...BUFKIT SOUNDINGS FOR KCID AND KDBQ LIMIT ANY
FROZEN PRECIP TO ONLY AN HOUR OR TWO BEFORE ENDING ALTOGETHER. THUS
HAVE REDUCED SNOW AMOUNTS AND ENDED PRECIP A FEW HOURS EARLIER THAN
PREVIOUS FORECAST. ..DMD..
.LONG TERM...SUNDAY NIGHT THROUGH NEXT SATURDAY
HIGH PRESSURE AT THE SURFACE MIGRATING THROUGH THE NORTHERN PLAINS
INTO THE UPPER MS VALLEY TO BRING NEAR TO SLIGHTLY BELOW NORMAL
TEMPERATURES FROM SUNDAY NIGHT THROUGH WEDNESDAY. THROUGH THIS
PERIOD...MODELS IN GENERAL AGREEMENT FEATURING AN UPPER LEVEL
POSITIVE TILT LONG WAVE TROUGH TRANSITIONING EAST THROUGH THE CENTRAL
U.S....SUPPRESSING THE MAIN BAROCLINIC AXIS AND STORM TRACK WELL TO
THE SOUTHEAST. A WAVE OF LOW PRESSURE TRACKING ALONG THE OHIO RIVER
MONDAY WILL SPREAD SNOW INTO PORTIONS OF MO AND IL...AND WILL KEEP
ONLY SLIGHT CHANCE POPS CONFINED TO THE FAR EAST AND SOUTH MONDAY
NIGHT ON THE EXTREME NW EDGE OF THIS SYSTEM. OTHERWISE...NO
PRECIPITATION IS EXPECTED...BUT HIGH LEVEL LIFT AND MOISTURE ALOFT
AHEAD OF THE UPPER TROUGH AXIS WILL FAVOR MOSTLY CLOUDY SKIES FOR
MUCH OF MON THROUGH WED.
THU TROUGH SAT...MODEL CONSENSUS INDICATES A COLD FRONT DROPPING
SOUTH THROUGH THE REGION LATE THURSDAY...FOLLOWED BY MUCH COLDER
TEMPERATURES FRIDAY AND SATURDAY FOLLOWING A FRESH INFLUX OF COLD
AIR AT 850 MB THAT HAS BEEN BUILDING WELL TO THE NORTH. THERE
CONTINUES TO BE CONSIDERABLE DIFFERENCES WITH THE TIMING AND
PLACEMENT OF CRITICAL UPPER LEVEL TROUGHS AND SURFACE FEATURES IN
THIS TIME FRAME...THUS THE POTENTIAL FOR PRECIPITATION REMAINS LOW
CONFIDENCE. THE CURRENT SUITE OF MODELS USED IN THE EXTENDED
SUPPORTS OUR SLIGHT TO LOW END CHANCES FOR LIGHT SNOW FOR THU NIGHT
FOLLOWING THE PASSAGE OF THE COLD FRONT. AHEAD OF THIS FRONT...HIGHS
THURSDAY SHOULD REACH INTO THE 30S IN MOST AREAS. THIS IS FOLLOWED
BY 20S FRIDAY AND SATURDAY WITH OVERNIGHT LOWS IN THE SINGLE DIGITS
AND TEENS. ..SHEETS..
&&
.AVIATION...
IFR CIGS AND VSBYS WILL RETURN TO AREA TAF SITES THIS EVENING AS A
LARGE AREA OF RAIN MOVES ACROSS THE REGION IN ASSOCIATION WITH A
COLD FRONT. RAIN WILL END BETWEEN 04/10Z AND 04/13Z...AND IS
EXPECTED TO CHANGE TO SNOW BRIEFLY BEFORE ENDING AT KCID AND KDBQ.
VFR CONDITIONS ARE EXPECTED TO RETURN TO AREA TAF SITES BY SUNDAY
04/18Z. ALSO OF NOTE...WITH THE PASSAGE OF THE FRONT GUSTY WINDS
WILL SHIFT FROM SOUTHEAST TO NORTH. ..DMD..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
DMD/SHEETS/DMD
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
207 PM CST SAT DEC 3 2011
.DISCUSSION...
SNOW HAS BEGUN TO SRPEAD INTO S MN AND WILL CONTINUE TO EXPAND NE
RAPIDLY DURING THE REMAINDER OF THE AFTERNOON. A BIT OF SATURATION
LEFT TO DO IN LOWER LEVELS BUT CIGS ARE BEGINNING TO LOWER ACROSS
S MN. IR SATELLITE SHOWS ELONGATED VORT FROM W KS INTO SC NEB
LIFTING NE. GFS/NAM SIMILAR ON TIMING BRINGING MAIN VORT INTO SC MN
BY 00Z AND THEN LIFTING INTO CENTRAL WI BY 06Z. GFS HAS INCREASED
QPF VALUES A BIT MORE TOWARD THE NAM SOLUTION. INCREASED SNOW
AMOUNTS A BIT ACROSS AREAS FROM MKT TO SE METRO BASED LARGELY ON
TRACK OF SURFACE/850 MB LOW CENTERS. HEAVY SNOW OFTEN SETS UP 70
TO 90 MILES N OF 850 MB LOW TRACK..AND 850 MB LOW TRACKS FROM SW
IA TO JUST S OF LSE BY 06Z THEN INTO E UPR MICHIGAN BY 12Z. KEPT
SNOW AMOUNTS IN THE 3 TO 6 INCH ADVISORY. FAVORABLE ISENTROPIC
LIFT COMES THRU RATHER QUICKLY WITH 3-3.5G/KG SO HESITATE TO GO
ANY HIGHER. WILL BE A PERIOD FROM AROUND 22Z TO 05Z WHERE ADVISORY
AREA WILL BE UNDER STRONG UPPER DIVERENGE FROM COUPLED UPPER JET...
FAVORABLE DENDRITIC TEMPERATURES AND STRONG 600 MB FULL WIND
FRONTOGENSIS WHICH COULD BRING A PERIOD OF A FEW HOURS OF
VISIBILITY INTO THE 1/2 SM RANGE AS FAR N AS MSP. LIKE THE TIMING
OF THE RUC BUFKIT SNOW ACCUMS IN THAT WINDOW. DECREASED SNOW
AMOUNTS SLIGHTLY IN W SIDE OF ADVY AREA AROUND SPRINGFIELD AND
GAYLORD. ADVISORY WILL LIKELY BE ABLE TO BE EXPIRED BY 06Z ACROSS
MUCH OF THE MN CWA WITH NO SIGNIFICANT WIND EXPECTED IN WAKE OF
SNOW.
COOLER FOR SUNDAY...BUT TROF DROPPING OUT OF CANADA WILL BACK
WINDS ENUF TO KEEP MAIN PUSH OF COLD AIR NORTH OF AREA. AS THIS
SYSTEM MOVES THRU COLD AIR WILL MOVE IN FOR MONDAY WITH HIGHS ONLY
IN THE TEEN TO MID 20S. SLIGHT MODERATION FOR WEDNESDAY AS WEAK
TROF MOVES ACROSS AREAK. AFTER THAT AREA REMAINS IN COLD AND DRY
NW FLOW AT LEAST UNTIL NEXT WEEKEND.
WITH SNOW COVER EXPECTED TONIGHT ACROSS S MN INTO WC WI WILL BE SOME
SOME MORNINGS WHERE WE SHOULD GET MIN TEMPS DOWN NEAR
ZERO...TUESDAY AND PROBABLY AGAIN FRIDAY/SATURDAY.
.AVIATION... /18Z TAF ISSUANCE/
STRONG LIFT NOW MOVING NORTHEAST ACROSS IOWA. SATURATION DEVELOPING
OVER FAR SOUTHERN MN WITH MVFR/IFR CONDITIONS OVER THE SOUTHEAST
CORNER OF THE STATE AND NOW LIFTING TO THE NORTH ACROSS WEST CENTRAL
WISCONSIN. EXPECT SNOW LINE TO REMAIN EAST OF KSTC TO NEAR KRWF
DURING THE EVENT. LOWEST CEILINGS LIFR/IFR TO REMAIN IN SNOW AREA
OVER THE EASTERN AREAS. COULD STILL SEE SOME 1/2SM SN REPORTS OVER
SOUTHEAST MN/WEST CENTRAL WISCONSIN INTO THE EVENING AS THIS SYSTEM
LIFTS NORTHEAST. MVFR CIGS EXPECTED INTO KAXN WITH CAA PATTERN
BEHIND SURFACE FRONT. THIS MAY LINGER LONGER INTO THE NIGHT AS
WELL...BEFORE SIGNIFICANT DRYING OCCURS. OTHERWISE...SNOW EXITING
THE EASTERN PORTION OF THE AREA 06Z-12Z SUNDAY PERIOD WITH
INCREASING CEILING HEIGHTS TO MVFR. SHOULD MAINTAIN MVFR CIGS
THROUGH THE MORNING. WITH BOUNDARY IN THE VCNTY EXPECT NORTHWEST
WINDS 10 KNOTS OR LESS OVER THE WESTERN AREAS AND LIGHT
SOUTH/SOUTHEAST BECOMING NORTH OVER THE EASTERN AREAS.
KMSP...MOISTURE/LIFT MOVING NORTH QUICKLY THIS AFTERNOON WITH
RAPIDLY CHANGING CONDITIONS DEVELOPING AFTER 21Z WITH SNOW AND
IFR/LIFR DEVELOPING THROUGH 00Z. APPEARS HEAVIEST ACCUMULATIONS
STILL OCCURRING IN THE 23Z-05Z PERIOD. ACCUMULATION AT THE AIRPORT
SHOULD RANGE FROM 2-3 INCHES. IMPROVING CONDITIONS AFTER 05Z WITH
LOWER CLOUDS REMAINING THROUGH MUCH OF SUNDAY MORNING...THOUGH VFR
POSSIBLE AFTER 14Z SUNDAY. LIGHT SOUTH WINDS EXPECTED TO BECOME MORE
NORTHWEST DURING THE PERIOD...BUT SHOULD REMAIN 10 KNOTS OR LESS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...WINTER WEATHER ADVISORY UNTIL 6 AM CST SUNDAY FOR ANOKA-BLUE
EARTH-BROWN-CARVER-CHISAGO-DAKOTA-FARIBAULT-FREEBORN-
GOODHUE-HENNEPIN-LE SUEUR-MARTIN-NICOLLET-RAMSEY-RICE-SCOTT-
SIBLEY-STEELE-WASECA-WASHINGTON-WATONWAN.
WI...WINTER WEATHER ADVISORY UNTIL 6 AM CST SUNDAY FOR BARRON-
CHIPPEWA-DUNN-EAU CLAIRE-PEPIN-PIERCE-POLK-RUSK-ST. CROIX.
&&
$$
BAP/DWE
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1205 PM CST SAT DEC 3 2011
.UPDATE...
OLD STATIONARY FRONT THAT WAS OFF OUR NORTHWEST CWA EDGE...HAS
SEEPED BACK SOUTHEAST TO A CISCO...POSSUM KINGDOM LAKE...JACKSBORO
LINE WITH THE HELP OF ONGOING RAINFALL. TEMPERATURES CURRENTLY IN
THE 45-50 DEGREE RANGE BEHIND THE FRONT AT BRECKENRIDGE AND
GRAHAM AND SHOULD REMAIN COOL/WET THE REMAINDER OF THE AFTERNOON.
ELSEWHERE...SHOWERS WILL CONTINUE TO SPREAD SLOWLY EAST WITH MILD
CONDITIONS IN THE 60S TO EVEN LOWER 70S ACROSS OUR SOUTHEAST
COUNTIES WITH GUSTY SOUTHEAST WINDS 15-20 MPH.
05
&&
.AVIATION...
FOR THE 18Z TAFS...CONCERNS ARE CLOUD TRENDS AND TIMING OF
RAIN OVERNIGHT.
WARM AIR ADVECTION AHEAD OF A COLD FRONT CONTINUES ACROSS NORTH
TEXAS TODAY. THIS IS RESULTING IN WIDESPREAD RAIN AND IFR/MVFR
CONDITIONS ACROSS THE REGION. THERE IS ALSO A LARGE AREA OF LIGHT
TO MODERATE RAIN AND SHOWERS APPROACHING THE METROPLEX TAF SITES
AT THIS HOURS. EXPECT ON-AND-OFF RAIN AND SHOWERS TO CONTINUE AT
ALL TAF SITES FOR THE REMAINDER OF THE DAY.
MOST OF THE IFR CEILINGS HAVE BEEN ACROSS PARTS OF TARRANT COUNTY
AND POINTS WEST OF THERE...MOSTLY AFFECTING KFTW AND SOMETIMES
KAFW. THINK LOW END MVFR WILL CONTINUE TO AFFECT THE METROPLEX TAF
SITES WITH OCCASIONAL IFR CONDITIONS BETWEEN 800-900 FEET THROUGH
THE MID AFTERNOON HOURS. CEILINGS WILL LIKELY REMAIN BETWEEN
1000-1500 FEET FOR THE MOST PART THIS AFTERNOON. AFTER THIS BAND
OF RAIN EVENTUALLY MOVES THROUGH THIS EVENING...CEILINGS MAY
ACTUALLY IMPROVE TO VFR FOR A FEW HOURS. IT IS POSSIBLE THAT LIGHT
RAIN MAY CONTINUE INTO THE OVERNIGHT HOURS. AT KACT...MVFR
CONDITIONS WILL PREVAIL THIS AFTERNOON.
A COLD FRONT WILL ARRIVE OVERNIGHT BRINGING RAIN AND
MVFR...POSSIBLY IFR...CONDITIONS BACK TO THE REGION. BREEZY NORTH
WINDS WILL OCCUR BEHIND THE FRONT AND THE RAIN WILL CONTINUE
THROUGH THE DAY ON SUNDAY.
ONE LAST NOTE...THE MODELS ARE SLOWING DOWN THE TIMING OF FROZEN
PRECIPITATION FROM MONDAY TO MONDAY NIGHT AND CONFIDENCE REMAINS
LOW THAT WINTER PRECIP WILL AFFECT THE AIRPORTS THAT NIGHT.
FORECASTED TEMPERATURES ARE NOW WARMER THAN PREVIOUS MODEL RUNS
BUT SOME FREEZING DRIZZLE MAY AFFECT THE AIRPORTS.
82/JLD
&&
.PREV UPDATE...
.UPDATE...
ISSUING A MINOR UPDATE TO RAIN TRENDS TODAY PER CURRENT REGIONAL
RADARS AND 3KM/4KM WRF AND HRRR TRENDS. STREAMER SHOWERS IN WARM
ADVECTION REGIME LITTLE MORE NUMEROUS THAN EXPECTED ACROSS THE
EASTERN COUNTIES...WHILE MORE LINEAR BAND OF SHOWERS WITH ISOLATED
EMBEDDED THUNDER NOW ARRIVING INTO NORTHWEST COUNTIES ASSOCIATED
WITH LARGE SCALE LIFT ASSOCIATED WITH A SHORTWAVE MOVING UP INTO
OKLAHOMA.
HAVE BASICALLY TRENDED LIKELY TO CATEGORICAL POPS ACROSS THE NORTH
WITH LOWER CHANCES ACROSS THE SOUTH WHERE FORCING WILL BE WEAKER
AND RAIN MORE SCATTERED IN NATURE. RAINFALL AMOUNTS TO BE LIGHT
OVERALL WITH LESS THAN A TENTH OF AN INCH EXPECTED...HOWEVER
ISOLATED HEAVIER AMOUNTS TO BETWEEN BETWEEN A QUARTER AND HALF
INCH MAY BE POSSIBLE WITH ANY EMBEDDED THUNDERSTORMS NEAR THE RED
RIVER.
REGARDING POSSIBLE WINTER WEATHER LATE SUNDAY NIGHT THROUGH MONDAY...
12Z MODEL RUNS ARE NOW ARRIVING THIS MORNING AND A MAJORITY OF
THEM...INCLUDING THE SREF ENSEMBLE ARE SHOWING A SLOWER TREND ON
THE ARRIVAL OF THE DEEPER COLD AIR AND ANY TRANSITION TO A WINTRY
MIXTURE ON MONDAY. IT APPEARS THAT OUTSIDE OF THE NORTHWEST COUNTIES...
MANY AREAS MAY NOT SEE ANY MIXTURE OR TRANSITION UNTIL LATE IN DAY
MONDAY OR POSSIBLY EVEN MONDAY EVENING. WE WILL CONTINUE TO
ANALYZE THE NEW DATA AND MAKE ANY NECESSARY ADJUSTMENTS TO THE
FORECAST ON THE AFTERNOON PACKAGE.
05/
&&
.PREV DISCUSSION... /ISSUED 413 AM CST SAT DEC 3 2011/
LOW LEVEL WARM AIR ADVECTION WILL PREVAIL ACROSS NORTH TEXAS
TODAY AS A WARM FRONT CONTINUES TO LIFT NORTH OF THE REGION. LARGE
SCALE LIFT WILL ALSO BE ON THE INCREASE FROM WEST TO EAST TODAY AS
PIECES OF ENERGY ASSOCIATED WITH A DEEP UPPER LOW OVER THE
SOUTHWESTERN UNITED STATES EJECT NORTHEAST ACROSS THE REGION. THE
BEST RAIN CHANCES TODAY WILL BE ACROSS THE NORTHWEST SECTIONS OF
NORTH TEXAS WHERE LIFT WILL BE MAXIMIZED. SOME ISOLATED THUNDER IS
ALSO POSSIBLE TODAY DUE TO INCREASING ELEVATED INSTABILITY.
A COLD FRONT WILL MOVE SOUTHEAST ACROSS NORTH TEXAS TONIGHT AND
PROVIDE ADDITIONAL LIFT FOR RAIN AND ISOLATED THUNDERSTORMS. THE
COLD FRONT WILL BRING MUCH COOLER AIR TO THE REGION WITH LOWS
SUNDAY MORNING COOLING INTO THE 30S ACROSS THE NORTHWEST ZONES.
FOR NOW IT APPEARS THAT ALL TEMPERATURES WILL REMAIN ABOVE
FREEZING SUNDAY MORNING.
AN INTERESTING PATTERN WILL EVOLVE LATE SUNDAY INTO MONDAY WITH
COLD AIR IN PLACE AT THE SURFACE AND UPPER LEVEL LOW PRESSURE STILL
TO THE WEST/SOUTHWEST OF THE REGION. THIS WILL RESULT IN MOISTURE
RIDING UP AND OVER THE WEDGE OF COLD AIR AT THE SURFACE...THUS
PROVIDING LIFT FOR AREAS OF RAIN SUNDAY AND SUNDAY NIGHT. THE
FORECAST GETS COMPLICATED IN THE PREDAWN HOURS MONDAY MORNING AS
SURFACE TEMPERATURES COOL TO NEAR FREEZING IN SOME LOCATIONS. PREVIOUS
MODEL SOLUTIONS WERE INDICATING SUBFREEZING TEMPERATURES ACROSS
THE NORTHWEST ZONES JUST BEFORE SUNRISE MONDAY. HOWEVER...THE
LATEST MODEL SOLUTIONS ALL KEEP SURFACE TEMPERATURES ABOVE
FREEZING THROUGH MONDAY EVENING. THIS SEEMS VERY PLAUSIBLE BASED ON
CURRENT SURFACE ANALYSIS OF TEMPERATURES OVER THE CENTRAL AND HIGH
PLAINS. THEREFORE...HAVE DECIDED TO KEEP ALL TEMPERATURES ABOVE
FREEZING THROUGH MONDAY EVENING WHICH WILL ELIMINATE THE POTENTIAL
FOR FREEZING RAIN. THE GFS AND ECMWF FORECAST SOUNDINGS DO
INDICATE THAT TEMPERATURES WILL FALL BELOW FREEZING JUST ABOVE
THE SURFACE AND THAT ONLY A WEAK WARM NOSE WILL EXIST.
THEREFORE...THE POTENTIAL FOR ACCUMULATING SLEET WILL BE LOW. THE
GFS DOES INDICATE SATURATION OF THE DENDRITIC GROWTH ZONE ON
MONDAY ACROSS ABOUT THE NORTHWEST HALF OF THE REGION WHILE THE
ECMWF AND THE NAM SHOW DRYING IN THAT LAYER. IF THE GFS SOLUTION
VERIFIES THE NORTHWEST HALF OF THE REGION COULD SEE A MIX OF LIGHT
RAIN AND LIGHT SNOW CHANGE OVER TO ALL LIGHT SNOW THROUGH THE DAY.
THERE WILL BE A LOW POTENTIAL FOR VERY LIGHT ACCUMULATIONS ACROSS
THE NORTHWEST ZONES AND ALMOST NO ACCUMULATIONS FARTHER SOUTH AND
SOUTHEAST. IF THE ECMWF SOLUTION VERIFIES ONLY COLD LIGHT RAIN OR
MAYBE MIX OF LIGHT RAIN AND LIGHT SLEET OR LIGHT SNOW WILL FALL.
BOTH SOLUTION KEEP INSTABILITY ON THE LOW SIDE SO THE POTENTIAL
FOR CONVECTIVE BANDING OF PRECIP IS ALSO LOW. FOR NOW WILL SIDE A
BIT CLOSER TO THE COLDER GFS SOLUTION SINCE THE MODELS MAY HAVE
OVERDONE THE WARM UP SLIGHTLY. WE WILL HAVE TO KEEP A CLOSE EYE ON
TEMPERATURE AND MOISTURE PROFILES OVER THE NEXT 24 TO 48 HOURS AS
EVEN SLIGHT CHANGES COULD CHANGE THE FORECAST DRASTICALLY.
PRECIPITATION CHANCES SHOULD COME TO AN END MONDAY EVENING AS
ISENTROPIC DOWNGLIDE INCREASES. THE WESTERN U.S. TROUGH WILL
FINALLY MOVE ACROSS THE REGION TUESDAY AND DRY NORTHWEST TO
WESTERLY FLOW WILL SET UP ACROSS NORTH TEXAS THROUGH THE WEEKEND
AS AN UPPER TROUGH DEVELOPS OVER THE NORTHERN AND CENTRAL PLAINS.
AFTER A COLD START TO THE WEEK...TEMPERATURES WILL START TO
REBOUND BY THE MIDDLE OF THE WEEK AS LOW LEVEL MOISTURE RETURNS.
HOWEVER...A COLD FRONT WILL MOVE ACROSS THE REGION LATE THURSDAY
THROUGH FRIDAY AND COOL TEMPERATURES WELL BELOW SEASONAL NORMALS AGAIN.
THE COLD FRONT SHOULD COME THROUGH NORTH TEXAS DRY DUE TO INSUFFICIENT
MOISTURE AND LACK OF UPPER LEVEL DYNAMICS. 79
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 67 42 48 37 44 / 70 70 70 80 60
WACO, TX 69 46 47 39 44 / 40 80 70 80 60
PARIS, TX 63 45 48 37 44 / 60 80 80 80 60
DENTON, TX 64 38 45 36 39 / 80 70 70 80 60
MCKINNEY, TX 67 41 48 36 41 / 70 80 70 80 60
DALLAS, TX 68 42 44 36 42 / 70 70 70 80 60
TERRELL, TX 69 44 49 38 43 / 60 70 80 80 60
CORSICANA, TX 71 47 49 39 43 / 40 80 80 80 60
TEMPLE, TX 71 48 48 39 46 / 30 80 70 70 60
MINERAL WELLS, TX 61 37 41 33 36 / 70 60 60 70 60
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
82/05
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1135 AM CST SAT DEC 3 2011
.AVIATION...
FOR THE 18Z TAFS...CONCERNS ARE CLOUD TRENDS AND TIMING OF
RAIN OVERNIGHT.
WARM AIR ADVECTION AHEAD OF A COLD FRONT CONTINUES ACROSS NORTH
TEXAS TODAY. THIS IS RESULTING IN WIDESPREAD RAIN AND IFR/MVFR
CONDITIONS ACROSS THE REGION. THERE IS ALSO A LARGE AREA OF LIGHT
TO MODERATE RAIN AND SHOWERS APPROACHING THE METROPLEX TAF SITES
AT THIS HOURS. EXPECT ON-AND-OFF RAIN AND SHOWERS TO CONTINUE AT
ALL TAF SITES FOR THE REMAINDER OF THE DAY.
MOST OF THE IFR CEILINGS HAVE BEEN ACROSS PARTS OF TARRANT COUNTY
AND POINTS WEST OF THERE...MOSTLY AFFECTING KFTW AND SOMETIMES
KAFW. THINK LOW END MVFR WILL CONTINUE TO AFFECT THE METROPLEX TAF
SITES WITH OCCASIONAL IFR CONDITIONS BETWEEN 800-900 FEET THROUGH
THE MID AFTERNOON HOURS. CEILINGS WILL LIKELY REMAIN BETWEEN
1000-1500 FEET FOR THE MOST PART THIS AFTERNOON. AFTER THIS BAND
OF RAIN EVENTUALLY MOVES THROUGH THIS EVENING...CEILINGS MAY
ACTUALLY IMPROVE TO VFR FOR A FEW HOURS. IT IS POSSIBLE THAT LIGHT
RAIN MAY CONTINUE INTO THE OVERNIGHT HOURS. AT KACT...MVFR
CONDITIONS WILL PREVAIL THIS AFTERNOON.
A COLD FRONT WILL ARRIVE OVERNIGHT BRINGING RAIN AND
MVFR...POSSIBLY IFR...CONDITIONS BACK TO THE REGION. BREEZY NORTH
WINDS WILL OCCUR BEHIND THE FRONT AND THE RAIN WILL CONTINUE
THROUGH THE DAY ON SUNDAY.
ONE LAST NOTE...THE MODELS ARE SLOWING DOWN THE TIMING OF FROZEN
PRECIPITATION FROM MONDAY TO MONDAY NIGHT AND CONFIDENCE REMAINS
LOW THAT WINTER PRECIP WILL AFFECT THE AIRPORTS THAT NIGHT.
FORECASTED TEMPERATURES ARE NOW WARMER THAN PREVIOUS MODEL RUNS
BUT SOME FREEZING DRIZZLE MAY AFFECT THE AIRPORTS.
82/JLD
&&
.UPDATE...
ISSUING A MINOR UPDATE TO RAIN TRENDS TODAY PER CURRENT REGIONAL
RADARS AND 3KM/4KM WRF AND HRRR TRENDS. STREAMER SHOWERS IN WARM
ADVECTION REGIME LITTLE MORE NUMEROUS THAN EXPECTED ACROSS THE
EASTERN COUNTIES...WHILE MORE LINEAR BAND OF SHOWERS WITH ISOLATED
EMBEDDED THUNDER NOW ARRIVING INTO NORTHWEST COUNTIES ASSOCIATED
WITH LARGE SCALE LIFT ASSOCIATED WITH A SHORTWAVE MOVING UP INTO
OKLAHOMA.
HAVE BASICALLY TRENDED LIKELY TO CATEGORICAL POPS ACROSS THE NORTH
WITH LOWER CHANCES ACROSS THE SOUTH WHERE FORCING WILL BE WEAKER
AND RAIN MORE SCATTERED IN NATURE. RAINFALL AMOUNTS TO BE LIGHT
OVERALL WITH LESS THAN A TENTH OF AN INCH EXPECTED...HOWEVER
ISOLATED HEAVIER AMOUNTS TO BETWEEN BETWEEN A QUARTER AND HALF
INCH MAY BE POSSIBLE WITH ANY EMBEDDED THUNDERSTORMS NEAR THE RED
RIVER.
REGARDING POSSIBLE WINTER WEATHER LATE SUNDAY NIGHT THROUGH MONDAY...
12Z MODEL RUNS ARE NOW ARRIVING THIS MORNING AND A MAJORITY OF
THEM...INCLUDING THE SREF ENSEMBLE ARE SHOWING A SLOWER TREND ON
THE ARRIVAL OF THE DEEPER COLD AIR AND ANY TRANSITION TO A WINTRY
MIXTURE ON MONDAY. IT APPEARS THAT OUTSIDE OF THE NORTHWEST COUNTIES...
MANY AREAS MAY NOT SEE ANY MIXTURE OR TRANSITION UNTIL LATE IN DAY
MONDAY OR POSSIBLY EVEN MONDAY EVENING. WE WILL CONTINUE TO
ANALYZE THE NEW DATA AND MAKE ANY NECESSARY ADJUSTMENTS TO THE
FORECAST ON THE AFTERNOON PACKAGE.
05/
&&
.PREV DISCUSSION... /ISSUED 413 AM CST SAT DEC 3 2011/
LOW LEVEL WARM AIR ADVECTION WILL PREVAIL ACROSS NORTH TEXAS
TODAY AS A WARM FRONT CONTINUES TO LIFT NORTH OF THE REGION. LARGE
SCALE LIFT WILL ALSO BE ON THE INCREASE FROM WEST TO EAST TODAY AS
PIECES OF ENERGY ASSOCIATED WITH A DEEP UPPER LOW OVER THE
SOUTHWESTERN UNITED STATES EJECT NORTHEAST ACROSS THE REGION. THE
BEST RAIN CHANCES TODAY WILL BE ACROSS THE NORTHWEST SECTIONS OF
NORTH TEXAS WHERE LIFT WILL BE MAXIMIZED. SOME ISOLATED THUNDER IS
ALSO POSSIBLE TODAY DUE TO INCREASING ELEVATED INSTABILITY.
A COLD FRONT WILL MOVE SOUTHEAST ACROSS NORTH TEXAS TONIGHT AND
PROVIDE ADDITIONAL LIFT FOR RAIN AND ISOLATED THUNDERSTORMS. THE
COLD FRONT WILL BRING MUCH COOLER AIR TO THE REGION WITH LOWS
SUNDAY MORNING COOLING INTO THE 30S ACROSS THE NORTHWEST ZONES.
FOR NOW IT APPEARS THAT ALL TEMPERATURES WILL REMAIN ABOVE
FREEZING SUNDAY MORNING.
AN INTERESTING PATTERN WILL EVOLVE LATE SUNDAY INTO MONDAY WITH
COLD AIR IN PLACE AT THE SURFACE AND UPPER LEVEL LOW PRESSURE STILL
TO THE WEST/SOUTHWEST OF THE REGION. THIS WILL RESULT IN MOISTURE
RIDING UP AND OVER THE WEDGE OF COLD AIR AT THE SURFACE...THUS
PROVIDING LIFT FOR AREAS OF RAIN SUNDAY AND SUNDAY NIGHT. THE
FORECAST GETS COMPLICATED IN THE PREDAWN HOURS MONDAY MORNING AS
SURFACE TEMPERATURES COOL TO NEAR FREEZING IN SOME LOCATIONS. PREVIOUS
MODEL SOLUTIONS WERE INDICATING SUBFREEZING TEMPERATURES ACROSS
THE NORTHWEST ZONES JUST BEFORE SUNRISE MONDAY. HOWEVER...THE
LATEST MODEL SOLUTIONS ALL KEEP SURFACE TEMPERATURES ABOVE
FREEZING THROUGH MONDAY EVENING. THIS SEEMS VERY PLAUSIBLE BASED ON
CURRENT SURFACE ANALYSIS OF TEMPERATURES OVER THE CENTRAL AND HIGH
PLAINS. THEREFORE...HAVE DECIDED TO KEEP ALL TEMPERATURES ABOVE
FREEZING THROUGH MONDAY EVENING WHICH WILL ELIMINATE THE POTENTIAL
FOR FREEZING RAIN. THE GFS AND ECMWF FORECAST SOUNDINGS DO
INDICATE THAT TEMPERATURES WILL FALL BELOW FREEZING JUST ABOVE
THE SURFACE AND THAT ONLY A WEAK WARM NOSE WILL EXIST.
THEREFORE...THE POTENTIAL FOR ACCUMULATING SLEET WILL BE LOW. THE
GFS DOES INDICATE SATURATION OF THE DENDRITIC GROWTH ZONE ON
MONDAY ACROSS ABOUT THE NORTHWEST HALF OF THE REGION WHILE THE
ECMWF AND THE NAM SHOW DRYING IN THAT LAYER. IF THE GFS SOLUTION
VERIFIES THE NORTHWEST HALF OF THE REGION COULD SEE A MIX OF LIGHT
RAIN AND LIGHT SNOW CHANGE OVER TO ALL LIGHT SNOW THROUGH THE DAY.
THERE WILL BE A LOW POTENTIAL FOR VERY LIGHT ACCUMULATIONS ACROSS
THE NORTHWEST ZONES AND ALMOST NO ACCUMULATIONS FARTHER SOUTH AND
SOUTHEAST. IF THE ECMWF SOLUTION VERIFIES ONLY COLD LIGHT RAIN OR
MAYBE MIX OF LIGHT RAIN AND LIGHT SLEET OR LIGHT SNOW WILL FALL.
BOTH SOLUTION KEEP INSTABILITY ON THE LOW SIDE SO THE POTENTIAL
FOR CONVECTIVE BANDING OF PRECIP IS ALSO LOW. FOR NOW WILL SIDE A
BIT CLOSER TO THE COLDER GFS SOLUTION SINCE THE MODELS MAY HAVE
OVERDONE THE WARM UP SLIGHTLY. WE WILL HAVE TO KEEP A CLOSE EYE ON
TEMPERATURE AND MOISTURE PROFILES OVER THE NEXT 24 TO 48 HOURS AS
EVEN SLIGHT CHANGES COULD CHANGE THE FORECAST DRASTICALLY.
PRECIPITATION CHANCES SHOULD COME TO AN END MONDAY EVENING AS
ISENTROPIC DOWNGLIDE INCREASES. THE WESTERN U.S. TROUGH WILL
FINALLY MOVE ACROSS THE REGION TUESDAY AND DRY NORTHWEST TO
WESTERLY FLOW WILL SET UP ACROSS NORTH TEXAS THROUGH THE WEEKEND
AS AN UPPER TROUGH DEVELOPS OVER THE NORTHERN AND CENTRAL PLAINS.
AFTER A COLD START TO THE WEEK...TEMPERATURES WILL START TO
REBOUND BY THE MIDDLE OF THE WEEK AS LOW LEVEL MOISTURE RETURNS.
HOWEVER...A COLD FRONT WILL MOVE ACROSS THE REGION LATE THURSDAY
THROUGH FRIDAY AND COOL TEMPERATURES WELL BELOW SEASONAL NORMALS AGAIN.
THE COLD FRONT SHOULD COME THROUGH NORTH TEXAS DRY DUE TO INSUFFICIENT
MOISTURE AND LACK OF UPPER LEVEL DYNAMICS. 79
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 68 42 48 37 44 / 70 70 70 70 60
WACO, TX 69 46 47 39 44 / 40 80 70 70 60
PARIS, TX 66 45 48 37 44 / 60 80 80 70 60
DENTON, TX 65 38 45 36 39 / 80 70 70 70 60
MCKINNEY, TX 65 41 48 36 41 / 70 80 70 70 60
DALLAS, TX 66 42 44 36 42 / 70 70 70 70 60
TERRELL, TX 67 44 49 38 43 / 60 70 80 70 60
CORSICANA, TX 70 47 49 39 43 / 40 80 80 70 60
TEMPLE, TX 71 48 48 39 46 / 30 80 70 70 60
MINERAL WELLS, TX 65 37 41 33 36 / 70 60 60 70 60
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
82/05
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1020 AM CST SAT DEC 3 2011
.UPDATE...
ISSUING A MINOR UPDATE TO RAIN TRENDS TODAY PER CURRENT REGIONAL
RADARS AND 3KM/4KM WRF AND HRRR TRENDS. STREAMER SHOWERS IN WARM
ADVECTION REGIME LITTLE MORE NUMEROUS THAN EXPECTED ACROSS THE
EASTERN COUNTIES...WHILE MORE LINEAR BAND OF SHOWERS WITH ISOLATED
EMBEDDED THUNDER NOW ARRIVING INTO NORTHWEST COUNTIES ASSOCIATED
WITH LARGE SCALE LIFT ASSOCIATED WITH A SHORTWAVE MOVING UP INTO
OKLAHOMA.
HAVE BASICALLY TRENDED LIKELY TO CATEGORICAL POPS ACROSS THE NORTH
WITH LOWER CHANCES ACROSS THE SOUTH WHERE FORCING WILL BE WEAKER
AND RAIN MORE SCATTERED IN NATURE. RAINFALL AMOUNTS TO BE LIGHT
OVERALL WITH LESS THAN A TENTH OF AN INCH EXPECTED...HOWEVER
ISOLATED HEAVIER AMOUNTS TO BETWEEN BETWEEN A QUARTER AND HALF
INCH MAY BE POSSIBLE WITH ANY EMBEDDED THUNDERSTORMS NEAR THE RED
RIVER.
REGARDING POSSIBLE WINTER WEATHER LATE SUNDAY NIGHT THROUGH MONDAY...
12Z MODEL RUNS ARE NOW ARRIVING THIS MORNING AND A MAJORITY OF
THEM...INCLUDING THE SREF ENSEMBLE ARE SHOWING A SLOWER TREND ON
THE ARRIVAL OF THE DEEPER COLD AIR AND ANY TRANSITION TO A WINTRY
MIXTURE ON MONDAY. IT APPEARS THAT OUTSIDE OF THE NORTHWEST COUNTIES...
MANY AREAS MAY NOT SEE ANY MIXTURE OR TRANSITION UNTIL LATE IN DAY
MONDAY OR POSSIBLY EVEN MONDAY EVENING. WE WILL CONTINUE TO
ANALYZE THE NEW DATA AND MAKE ANY NECESSARY ADJUSTMENTS TO THE
FORECAST ON THE AFTERNOON PACKAGE.
05/
&&
.AVIATION UPDATE...
MOST OF THE RAIN THIS MORNING HAS NOW MOVED EAST OF THE TAF
TERMINALS BUT SOME DRIZZLE OR LIGHT RAIN WILL CONTINUE THROUGH AT
LEAST THE MORNING HOURS. IFR CEILINGS ARE BEGINNING TO SPREAD
ACROSS TARRANT COUNTY...ALREADY AFFECTING KFTW...AND LIKELY MOVING
INTO THE REMAINING METROPLEX TAF SITES IN THE NEXT HOUR.
HOWEVER...THE CEILINGS ARE VARYING FROM 800-1300 FT. WILL PREVAIL
OVC010 AND TEMPO FOR LOWER CEILINGS EXPECTING THAT THE CEILINGS
WILL VARY AT TIMES. THE SAME TRENDS ARE EXPECTED AT KACT WITH
SITES TO THE WEST OF THE AIRPORT ALREADY REPORTING IFR CONDITIONS.
82/JLD
.../PREVIOUS AVIATION DISCUSSION/...
LOCAL 88D RADAR SHOWING ISENTROPIC PROCESS IS UNDERWAY FOR THE MORNING
WITH SCATTERED SHOWERS DEVELOPING AND SPREADING NORTHEAST RAPIDLY
ACROSS NORTH TEXAS. THIS PROCESS SHOULD CONTINUE THROUGH MIDDAY
WITH A POTENTIAL FOR ISOLATED THUNDER LATER THIS AFTERNOON. THERE
SHOULD BE A LULL IN THE PRECIPITATION THIS EVENING AS LIFT EXITS
THE REGION. A STRONG COLD FRONT WILL MOVE THROUGH THE TAF SITES
LATER TONIGHT WITH RAIN GEARING UP AGAIN DUE TO A COMBINATION OF
FRONTAL AND SYNOPTIC LIFT.
WILL KEEP CIGS MVFR THROUGH MOST OF THE DAY WITH VFR CIGS ABOVE
5 KFT BETWEEN 03Z AND 09Z WHILE UPPER SUPPORT MOVES NORTHEAST. THE
NEXT BATCH OF PRECIPITATION IS EXPECTED TO DEVELOP LATE TONIGHT AND
CONTINUE THROUGH MIDDAY MONDAY.
A TRANSITION TO A LIGHT RAIN LIGHT SNOW MIX IS EXPECTED ACROSS
THE METROPLEX MONDAY FROM MID-MORNING ON...BUT ONLY A LIGHT
ACCUMULATION SNOW IS EXPECTED ON ELEVATED SURFACES. CONFIDENCE IN
THE CURRENT LIGHT SNOW FORECAST IS MODERATE. 75
82
&&
.PREV DISCUSSION... /ISSUED 413 AM CST SAT DEC 3 2011/
LOW LEVEL WARM AIR ADVECTION WILL PREVAIL ACROSS NORTH TEXAS
TODAY AS A WARM FRONT CONTINUES TO LIFT NORTH OF THE REGION. LARGE
SCALE LIFT WILL ALSO BE ON THE INCREASE FROM WEST TO EAST TODAY AS
PIECES OF ENERGY ASSOCIATED WITH A DEEP UPPER LOW OVER THE
SOUTHWESTERN UNITED STATES EJECT NORTHEAST ACROSS THE REGION. THE
BEST RAIN CHANCES TODAY WILL BE ACROSS THE NORTHWEST SECTIONS OF
NORTH TEXAS WHERE LIFT WILL BE MAXIMIZED. SOME ISOLATED THUNDER IS
ALSO POSSIBLE TODAY DUE TO INCREASING ELEVATED INSTABILITY.
A COLD FRONT WILL MOVE SOUTHEAST ACROSS NORTH TEXAS TONIGHT AND
PROVIDE ADDITIONAL LIFT FOR RAIN AND ISOLATED THUNDERSTORMS. THE
COLD FRONT WILL BRING MUCH COOLER AIR TO THE REGION WITH LOWS
SUNDAY MORNING COOLING INTO THE 30S ACROSS THE NORTHWEST ZONES.
FOR NOW IT APPEARS THAT ALL TEMPERATURES WILL REMAIN ABOVE
FREEZING SUNDAY MORNING.
AN INTERESTING PATTERN WILL EVOLVE LATE SUNDAY INTO MONDAY WITH
COLD AIR IN PLACE AT THE SURFACE AND UPPER LEVEL LOW PRESSURE STILL
TO THE WEST/SOUTHWEST OF THE REGION. THIS WILL RESULT IN MOISTURE
RIDING UP AND OVER THE WEDGE OF COLD AIR AT THE SURFACE...THUS
PROVIDING LIFT FOR AREAS OF RAIN SUNDAY AND SUNDAY NIGHT. THE
FORECAST GETS COMPLICATED IN THE PREDAWN HOURS MONDAY MORNING AS
SURFACE TEMPERATURES COOL TO NEAR FREEZING IN SOME LOCATIONS. PREVIOUS
MODEL SOLUTIONS WERE INDICATING SUBFREEZING TEMPERATURES ACROSS
THE NORTHWEST ZONES JUST BEFORE SUNRISE MONDAY. HOWEVER...THE
LATEST MODEL SOLUTIONS ALL KEEP SURFACE TEMPERATURES ABOVE
FREEZING THROUGH MONDAY EVENING. THIS SEEMS VERY PLAUSIBLE BASED ON
CURRENT SURFACE ANALYSIS OF TEMPERATURES OVER THE CENTRAL AND HIGH
PLAINS. THEREFORE...HAVE DECIDED TO KEEP ALL TEMPERATURES ABOVE
FREEZING THROUGH MONDAY EVENING WHICH WILL ELIMINATE THE POTENTIAL
FOR FREEZING RAIN. THE GFS AND ECMWF FORECAST SOUNDINGS DO
INDICATE THAT TEMPERATURES WILL FALL BELOW FREEZING JUST ABOVE
THE SURFACE AND THAT ONLY A WEAK WARM NOSE WILL EXIST.
THEREFORE...THE POTENTIAL FOR ACCUMULATING SLEET WILL BE LOW. THE
GFS DOES INDICATE SATURATION OF THE DENDRITIC GROWTH ZONE ON
MONDAY ACROSS ABOUT THE NORTHWEST HALF OF THE REGION WHILE THE
ECMWF AND THE NAM SHOW DRYING IN THAT LAYER. IF THE GFS SOLUTION
VERIFIES THE NORTHWEST HALF OF THE REGION COULD SEE A MIX OF LIGHT
RAIN AND LIGHT SNOW CHANGE OVER TO ALL LIGHT SNOW THROUGH THE DAY.
THERE WILL BE A LOW POTENTIAL FOR VERY LIGHT ACCUMULATIONS ACROSS
THE NORTHWEST ZONES AND ALMOST NO ACCUMULATIONS FARTHER SOUTH AND
SOUTHEAST. IF THE ECMWF SOLUTION VERIFIES ONLY COLD LIGHT RAIN OR
MAYBE MIX OF LIGHT RAIN AND LIGHT SLEET OR LIGHT SNOW WILL FALL.
BOTH SOLUTION KEEP INSTABILITY ON THE LOW SIDE SO THE POTENTIAL
FOR CONVECTIVE BANDING OF PRECIP IS ALSO LOW. FOR NOW WILL SIDE A
BIT CLOSER TO THE COLDER GFS SOLUTION SINCE THE MODELS MAY HAVE
OVERDONE THE WARM UP SLIGHTLY. WE WILL HAVE TO KEEP A CLOSE EYE ON
TEMPERATURE AND MOISTURE PROFILES OVER THE NEXT 24 TO 48 HOURS AS
EVEN SLIGHT CHANGES COULD CHANGE THE FORECAST DRASTICALLY.
PRECIPITATION CHANCES SHOULD COME TO AN END MONDAY EVENING AS
ISENTROPIC DOWNGLIDE INCREASES. THE WESTERN U.S. TROUGH WILL
FINALLY MOVE ACROSS THE REGION TUESDAY AND DRY NORTHWEST TO
WESTERLY FLOW WILL SET UP ACROSS NORTH TEXAS THROUGH THE WEEKEND
AS AN UPPER TROUGH DEVELOPS OVER THE NORTHERN AND CENTRAL PLAINS.
AFTER A COLD START TO THE WEEK...TEMPERATURES WILL START TO
REBOUND BY THE MIDDLE OF THE WEEK AS LOW LEVEL MOISTURE RETURNS.
HOWEVER...A COLD FRONT WILL MOVE ACROSS THE REGION LATE THURSDAY
THROUGH FRIDAY AND COOL TEMPERATURES WELL BELOW SEASONAL NORMALS AGAIN.
THE COLD FRONT SHOULD COME THROUGH NORTH TEXAS DRY DUE TO INSUFFICIENT
MOISTURE AND LACK OF UPPER LEVEL DYNAMICS. 79
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 68 42 48 37 44 / 70 70 70 70 60
WACO, TX 69 46 47 39 44 / 40 80 70 70 60
PARIS, TX 66 45 48 37 44 / 60 80 80 70 60
DENTON, TX 65 38 45 36 39 / 80 70 70 70 60
MCKINNEY, TX 65 41 48 36 41 / 70 80 70 70 60
DALLAS, TX 66 42 44 36 42 / 70 70 70 70 60
TERRELL, TX 67 44 49 38 43 / 60 70 80 70 60
CORSICANA, TX 70 47 49 39 43 / 40 80 80 70 60
TEMPLE, TX 71 48 48 39 46 / 30 80 70 70 60
MINERAL WELLS, TX 65 37 41 33 36 / 70 60 60 70 60
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
82/05
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
220 PM CST SAT DEC 3 2011
.SHORT TERM...TONIGHT AND SUNDAY.
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A DEVELOPING
LOW PRESSURE SYSTEM MOVING NORTHEAST OVER SOUTH-CENTRAL KANSAS JUST
AHEAD OF A SHORTWAVE TROUGH. ATTACHED TO THE SURFACE LOW TO THE
NORTHEAST RUNS A COLD FRONT OVER CENTRAL IOWA INTO NORTHWEST
WISCONSIN. FIRST BATCH OF PRECIP IS RIDING ALONG THE 850MB
BAROCLINIC ZONE OVER THE SOUTHEASTERN HALF OF WISCONSIN THOUGH SOME
BREAKS ARE SPREADING OVER EASTERN IOWA AND NORTHERN ILLINOIS...THAT
MAY SPELL A BREAK IN THE PRECIP FOR A BRIEF PERIOD LATE THIS
AFTERNOON OVER E-C WISCONSIN. THE MAIN AXIS OF PRECIP...HOWEVER...
EXISTS JUST TO THE EAST OF THE SURFACE LOW ON THE NOSE OF A 60 KT
LLJ AND UPPER DIVERGENT AREA WITHIN THE COUPLED JET. SOME HIGHER
REFLECTIVITIES ARE ALSO DEVELOPING OVER WESTERN WISCONSIN WITHIN A
STRENGTHENING FGEN ZONE...SO WILL JUST START THE WINTER HEADLINES
WITH THE AFTERNOON PACKAGE. AS THE LOW TRACKS NORTHEAST OVER THE
NEXT 24 HOURS...THE OBVIOUS CONCERNS ARE SNOW AMOUNTS AND
HEADLINES.
TONIGHT...FOLLOWED A SREF/GFS BLEND TONIGHT...WHICH SPLITS THE
DIFFERENCE BETWEEN THE STRONGER NAM AND WEAKER ECMWF WHILE KEEPING
THE CONSENSUS TRACK. LOW PRESSURE OVER THE CENTRAL PLAINS WILL
RAPIDLY MOVE NE TOWARDS THE MID-MISSISSIPPI VALLEY THIS
EVENING...AND NORTHERN LAKE MICHIGAN BY 12Z SUNDAY. AHEAD OF THE
LOW...A BEEFY LLJ WILL SHIFT INTO SOUTHERN WISCONSIN THIS
EVENING...THEREBY INCREASING CONVERGENCE ALONG THE STALLED
BAROCLINIC ZONE STRETCHING ACROSS THE STATE...AND 850-700MB FGEN IN
THE PROCESS. COMBINED WITH STRONG QG FORCING FROM SHORTWAVE ENERGY
AND A WIDE OPEN GULF (PWATS 150-200 PCT OF NORMAL)...THE BEEFY SLUG
OF PRECIP OVER THE PLAINS WILL HAVE NO TROUBLE SPREADING ACROSS THE
STATE THIS EVENING. PTYPE REMAINS PROBLEMATIC AS THE 12Z MODEL RUNS
HAVE TRENDED SLIGHTLY WARMER WITH THE THERMAL PROFILE AS THE LOW
PUSHES WARMER AIR ALOFT SLIGHTLY FARTHER NORTH THAN PREVIOUS RUNS.
THIS WILL PLACE THE RAIN-SNOW MIX AREA FROM WOOD COUNTY TO NORTHERN
OCONTO AND MARINETTE. NORTH OF THE RAIN-SNOW LINE SHOULD RESIDE THE
AXIS OF HEAVIEST SNOWFALL...WHICH LINES UP WITH THE EXTRAPOLATED
SOUTHERN EDGE OF THE COMMA HEAD FROM APPROX MERRILL TO CRANDON.
WITH SLIGHTLY COLDER AIR IN PLACE COMPARED TO THE FIRST SNOW STORM IN
NOVEMBER...SNOW RATIOS WILL RUN BETWEEN 10-14:1 OVER THIS AREA
ACCORDING TO THE COBB SNOWFALL ALGORITHM. WITH QPFS AROUND 0.4 TO
0.5 INCHES...THIS AMOUNTS TO A GOOD 4-6 INCH SWATH OF SNOW TONIGHT
(5 TO 7 INCHES OVERALL)...THOUGH THE BULK OF THE PRECIP WILL LIKELY FALL
THIS EVENING. THE FOX VALLEY AND LAKESHORE WILL RESIDE WITHIN THE
WARM SECTOR OF THE STORM...WHICH MEANS MOSTLY RAIN TONIGHT...THOUGH
SOME SNOW MAY MIX IN LATE. ENTERTAINED SOME THOUGHTS OF UPGRADING TO
A WARNING GIVEN THE HEAVY SNOW OBS UPSTREAM...BUT GIVEN THE
RELATIVELY LOW IMPACT OF THE SNOW (DURING THE NIGHT ON A
WEEKEND)...WILL STICK WITH ADVISORY HEADLINES. ALSO THOUGHT ABOUT
TRIMMING THE ADVISORY TO THE NW BY A ROW OF COUNTIES...BUT
COORDINATION WITH SURROUNDING OFFICES YIELDED A RELUCTANCE...DUE TO
THE SLOPPINESS OF THE MIX AND POTENTIAL FOR FREEZING DRIZZLE. AS A
RESULT...WILL KEEP CURRENT HEADLINES AS THEY CURRENTLY STAND BUT
STRESS THE HEAVY SNOWFALL RATES ARRIVING THIS EVENING.
SUNDAY...THE LOW PRESSURE WILL QUICKLY EXIT TO SOUTHEAST ONTARIO BY
18Z SUNDAY BUT WILL HAVE THE BACK EDGE OF THE COMMA HEAD SHIFTING NE
OVER N-C AND FAR NORTHEAST WISCONSIN. SOME MID-LEVEL FGEN WILL
LINGER WHICH WILL RESULT IN ANOTHER HALF INCH TO AN INCH OVER N-C
WISCONSIN EARLY IN THE MORNING. BUT OTHERWISE...SNOW WILL BE
TAPERING DOWN TO JUST FLURRIES IN THE MORNING...WHILE COLDER AIR
FILTERS ACROSS THE REGION. LOW LEVEL TROUGHINESS AND CYCLONIC FLOW
WILL HANG AROUND FOR MUCH OF THE DAY...SO NOT ANTICIPATING MUCH
CLEARING TOMORROW. HIGHS MAINLY IN THE LOW TO MIDDLE 30S.
.LONG TERM...SUNDAY NIGHT THROUGH NEXT SATURDAY...THE MAIN FCST
CONCERNS WILL BE MINOR LAKE EFFECT SNOW POTENTIAL OVER NORTHERN
WI EARLY IN THE PERIOD...THEN THE POTENTIAL FOR SNOW AND MUCH
COLDER TEMPERATURES WITH AN ARCTIC FRONTAL PASSAGE LATE NEXT
WEEK.
A STRONG...HIGH AMPLITUDE RIDGE WILL COVER THE EASTERN PACIFIC...
WESTERN CANADA AND THE WEST COAST OF THE U.S. EARLY IN THE PERIOD...
WITH A POSITIVELY-TILTED UPPER TROF EXTENDING FROM CENTRAL CANADA
INTO THE SOUTHWEST UNITED STATES. THIS UPPER TROF WILL MOVE THROUGH
WISCONSIN ON TUESDAY...WITH LITTLE IMPACT ON OUR WEATHER. SHORT-WAVE
ENERGY WILL TOP THE WESTERN RIDGE EARLY NEXT WEEK...THEN EVENTUALLY
HELP TO CARVE A BROAD TROF OVER THE CENTRAL U.S. BY THU/FRI. A
SURGE OF ARCTIC AIR IS EXPECTED TO ARRIVE IN WI LATE IN THE WEEK...
WITH H8 TEMPS PLUMMETING TO AROUND -20 C. THIS WILL LEAD TO OUR
COLDEST TEMPERATURES SO FAR THIS SEASON.
A LARGE RIDGE OF HIGH PRESSURE WILL BE CENTERED OVER THE NORTHERN
ROCKIES AND NORTHERN PLAINS SUN NGT INTO MON...WITH COLD NORTH
FLOW RESULTING IN SCT LAKE-EFFECT SNOW SHOWERS OVER MAINLY NC WI.
THE SNOW SHOWERS MAY LINGER INTO MONDAY NIGHT...BUT SHOULD COME TO
AN END ON TUESDAY AS THE RIDGE AXIS PUSHES ACROSS WI.
A WEAK COLD FRONT IS EXPECTED TO MOVE THROUGH THE REGION ON
WEDNESDAY...WITH A STRONGER ARCTIC FRONT ARRIVING SOMETIME DURING
THE THU/FRI TIME FRAME. DURING THIS PERIOD...LLVL FLOW IS EXPECTED
TO BE TOO WESTERLY FOR LK-EFFECT. THE ECMWF AND A FEW OF THE GFS
ENSEMBLE MEMBERS SUGGEST THAT A SFC WAVE WILL DEVELOP ALONG THE
ARCTIC BOUNDARY LATE IN THE WEEK...AS THE RRQ OF A STRONG UPPER
LEVEL JET PULLS THROUGH THE REGION. IF THIS PLAYS OUT...WE COULD
BRING SEE SEVERAL INCHES OF POWDERY SNOW SOMETIME DURING THE
THURSDAY NIGHT TO SATURDAY PERIOD. FOR NOW...WILL FOLLOW THE
CONCENSUS OF AREA OFFICES...AND JUST MENTION SMALL POPS ACROSS OUR
SOUTHERN AND EASTERN COUNTIES ON THU NGT/FRI. THERE IS A HIGHER
DEGREE OF CONFIDENCE IN A TREND TOWARD MUCH COLDER TEMPERATURES
LATE IN THE WEEK...ALTHOUGH THE NEW ECMWF IS SLOWER WITH THE
TIMING OF THE ARCTIC BOUNDARY. SUBSEQUENT FCSTS SHOULD BE BETTER
ABLE TO PINPOINT THE FRONTAL TIMING AND SNOWFALL POTENTIAL LATE
NEXT WEEK.
&&
.AVIATION...MVFR TO IFR CIGS/VSBYS PRIMARILY ACROSS THE
REGION...THOUGH 1/4SM VSBYS ARE HANGING TOUGH AT AUW/CWA. THE VERY
LOW VSBYS OVER THE CENTRAL WISCONSIN TAF SITES SHOULD IMPROVE ONCE
PRECIP ARRIVES EARLY THIS AFTERNOON. LOW PRESSURE WILL TRACK ACROSS
THE REGION TONIGHT. MODEL THERMAL PROFILES ARE VERY CLOSE TO THE
FREEZING MARK IN THE LOW LEVELS...SO INCLUDED A RAIN-SNOW MIX
THROUGH THIS EVENING AT CWA/AUW. WILL SEE MOSTLY RAIN OVER THE FOX
VALLEY IN THE WARM SECTOR UNTIL LATE TONIGHT WHEN RAIN SWITCHES OVER
TO SNOW. WILL SEE A PERIOD OF A FEW HOURS OF HEAVY SNOW AT RHI
THIS EVENING WHEN SHOULD SEE SEVERAL INCHES. THE PRECIP WILL BE
EXITING THE AREA LATE TONIGHT INTO TOMORROW MORNING FROM SW TO NE.
VSBYS AND CIGS WILL BE GRADUALLY IMPROVING AS THE SNOW DIMINISHES.
MPC
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 6 AM CST SUNDAY FOR WIZ005-010>013-
018-019-021-030-035.
&&
$$
MPC/TSK
AREA FORECAST DISCUSSION...UPDATED
NWS LA CROSSE WI
140 PM CST SAT DEC 3 2011
.SHORT TERM...TODAY THROUGH MONDAY NIGHT
343 AM CST SAT DEC 3 2011
MAIN FORECAST CONCERN IS ON MIXED PRECIPITATION THROUGH
TONIGHT...ALONG WITH SNOWFALL AMOUNTS.
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND 500MB HEIGHT ANALYSIS
SHOWED RIDGING OVER THE EAST PACIFIC...SPLIT TROUGHING FROM
MANITOBA SOUTHWEST INTO ARIZONA...AND BUILDING RIDGING FROM THE
SOUTHEASTERN U.S. INTO THE GREAT LAKES REGION. WITHIN THE SPLIT
TROUGHING...A POTENT SHORTWAVE WAS NOTED OVER SOUTHWEST NEW MEXICO
WITH A NICE BAROCLINIC LEAF ON WATER VAPOR NORTHEAST OF IT. 850MB
WINDS FAIRLY STRONG AHEAD OF THE SPLIT TROUGHING...RANGING FROM
40-60 KNOTS OUT OF THE SOUTH-SOUTHWEST FROM TEXAS INTO KANSAS AND
NORTHEAST INTO THE FORECAST AREA. THESE WINDS HAVE BEEN RAPIDLY
ADVECTING WARMER AIR AND MOISTURE NORTHWARD...CAUSING RAIN TO
BREAK OUT ACROSS IOWA...FAR SOUTHEASTERN MINNESOTA AND MUCH OF
WISCONSIN EXCLUDING THE NORTHWEST PART. 08Z PRECIPITABLE WATER
ANALYSIS FROM THE RUC SHOWS VALUES OF 0.75 TO 0.9 INCHES IN THE
SOUTHERN PORTION OF THE FORECAST AREA...OR ABOUT 200 PERCENT ABOVE
NORMAL. 2 METER AIR TEMPERATURES HAVE CLIMBED TO AT OR ABOVE 32F
AT MOST LOCATIONS AND DEWPOINTS ARE ALMOST THE SAME NOW. THIS
SHOULD BE REDUCING THE FREEZING OF THE RAIN AT THE SURFACE.
TODAY AND TONIGHT...SHORTWAVE OVER NEW MEXICO IS FORECAST TO
GRADUALLY ACCELERATE TO THE NORTHEAST DURING THIS PERIOD AS
A POTENT SHORTWAVE DROPS DOWN INTO MONTANA. INITIAL ISENTROPIC
LIFTING TAKING PLACE TO PRODUCE CURRENT PRECIPITATION SHOULD HOLD
FAIRLY STEADY THROUGH THE MORNING. WITH WARM ADVECTION OCCURRING...
ANY FREEZING OF THE PRECIPITATION SHOULD BE LIMITED TO BEFORE
13Z...THEN RAIN/DRIZZLE IS ANTICIPATED. DURING THE AFTERNOON...LOW
TO MID-LEVEL FRONTOGENESIS WILL INTENSIFY OVER THE SOUTHWEST
PORTION OF THE FORECAST AREA...SPREADING NORTHEAST DURING THE
EVENING. THIS FRONTOGENESIS IS CAUSED BY A COMBINATION FROM THE
DPVA PRODUCED AHEAD OF THE APPROACHING NEW MEXICO SHORTWAVE...AS
WELL AS A NEAR COUPLED UPPER JET STRUCTURE DEVELOPING. IN
ADDITION...CROSS-SECTIONS INDICATE THE PRESENCE OF SOME NEGATIVE
EPV ON TOP OF THE FRONTOGENESIS ZONE...ALLOWING FOR POTENTIAL FOR
A FEW CONVECTIVE ELEMENTS. WITH PRECIPITABLE WATER VALUES HOLDING
FAIRLY STEADY INTO THE EVENING...NEEDLESS TO SAY THE LATE
AFTERNOON INTO THE EVENING PERIOD IS OF MOST CONCERN FOR HEAVIEST
PRECIPITATION. GIVEN THE HIGHER PRECIPITATION RATES ALLOWING FOR
DIABATIC COOLING AND THE SURFACE FLOW TURNING NORTHERLY TO ALLOW FOR
COLD ADVECTION...THE AFTERNOON AND EVENING PRECIPITATION SHOULD
GRADUALLY CHANGE OVER TO SNOW...QUICKEST OVER THE NORTHWEST HALF
OF THE FORECAST AREA. 03.00Z MODEL QPF SPREADS ARE SOMEWHAT
HIGH...RANGING FROM 0.20-0.60 INCHES FOR 18-06Z. STILL...WITH SNOW
TO WATER RATIOS LIKELY TO STAY AROUND A 10 TO 1 AVERAGE GIVEN DEEP
AGGREGATION LAYER NOTED ON SOUNDINGS...LIKELY TO END UP WITH
SNOWFALL AMOUNTS IN THIS TIME WINDOW AT MOST UP TO 5 INCHES. SINCE
THIS IS AN INCH BELOW WARNING CRITERIA...AND MODELS TOO COLD
RIGHT NOW WITH HOURLY TEMPERATURES SUGGESTING PRECIPITATION COULD
END UP BEING EVEN MORE RAIN FOR THE AFTERNOON...AN ADVISORY SEEMS
TO BE THE BETTER REPLACEMENT FOR THE WATCH RIGHT NOW. DURING THE
OVERNIGHT HOURS...THE PRECIPITATION SHOULD SLOWLY START LIFTING TO
THE NORTHEAST WITH THE SHORTWAVE. HOWEVER...PLENTY OF LOW LEVEL
STILL EXISTS. THIS BRINGS UP A CONCERN...AS ONCE THE SHORTWAVE
MOVES IN THE ICE MAY SCOUR OUT...RESULTING IN RAIN/FREEZING RAIN.
THE BEST CHANCE FOR THIS TO OCCUR IS EAST OF A LINE FROM CHARLES
CITY IOWA TO LA CROSSE AND WISCONSIN RAPIDS. DID PUT IN A FEW
HUNDREDTHS OF ICE ACCUMULATION NEAR THIS LINE. WITH THE ICE
ACCUMULATION AND TO ADD A BUFFER IN CASE THE PRECIPITATION CHANGES
TO SNOW QUICKER TONIGHT...ADDED ANOTHER ROW OF COUNTIES JUST EAST
OF THE PREVIOUS WATCH FOR AN ADVISORY. REGARDING TEMPERATURES...
INCREASED THEM BOTH TODAY AND TONIGHT GIVEN CURRENT WARMER TRENDS.
SUNDAY THROUGH MONDAY NIGHT...MUCH QUIETER TIME PERIOD. SHORTWAVE
TROUGHING DIGGING INTO MONTANA TONIGHT IS FORECAST BY ALL MODELS
TO MARCH SLOWLY EAST...REACHING THE WESTERN END OF THE FORECAST
AREA AROUND 12Z TUESDAY. ALTHOUGH THE FORECAST AREA RESIDES IN
SOUTHWEST FLOW ALOFT...ALL OF THE SHORTWAVES IN THAT SOUTHWEST
FLOW TO HELP PRODUCE PRECIPITATION LOOK TO STAY TO THE SOUTHEAST
OF HERE. IN ADDITION...THE SHORTWAVE MOVING THROUGH TONIGHT HELPS
TO SCOUR OUT MUCH OF THE MOISTURE...NOTED BY PRECIPITABLE WATER
VALUES FALLING TO 0.25 INCH OR LESS BY 21Z SUNDAY. DID MAINTAIN
SOME LOW 20-30 PERCENT CHANCES FOR THE EASTERN TWO THIRDS OF THE
FORECAST AREA ON SUNDAY...DUE TO LINGERING LOW LEVEL LIFT.
AGAIN...THE PRESENCE OF ICE IS QUESTIONABLE...ESPECIALLY OVER
NORTHEAST IOWA AND SOUTHWEST WISCONSIN. AS A RESULT...HAVE
MENTIONED A SNOW/FREEZING DRIZZLE MIX. AFTER THAT...DRY WEATHER
WILL BE THE RULE...WITH ONLY SOME INCREASE OF MID/HIGH CLOUDS AS
THE MONTANA SHORTWAVE TROUGHING APPROACHES. BIGGER IMPACT
TEMPERATURES. 850MB TEMPS AT 12Z SUNDAY SHOULD RANGE FROM -4C EAST
TO -8C WEST. THESE COOL THROUGH THE DAY SUNDAY...SO HIGHS SHOULD
END UP CLOSE TO THE MORNING LOWS. FURTHER COOLING OF 850MB TEMPS
IS PROGGED FOR MONDAY...DROPPING TO -10 TO -14C. THEREFORE...
HIGHS IN MOST LOCATIONS LOOK TO ONLY TOP OUT IN THE 20S. MORE
TEENS AND SINGLE DIGIT READINGS ABOVE ZERO EXPECTED AT NIGHT WITH
NOCTURNAL COOLING.
.LONG TERM...TUESDAY THROUGH FRIDAY NIGHT
343 AM CST SAT DEC 3 2011
03.00Z ECMWF/GFS/CANADIAN AND GFS ENSEMBLES CONTINUE TO PAINT A
COLDER THAN NORMAL PATTERN FOR THE FORECAST AREA AS A POLAR VORTEX
SETS UP OVER HUDSON BAY BY LATE IN THE WEEK. SHORTWAVE TROUGH WILL
MOVE EAST TO WEST ACROSS THE AREA ON TUESDAY...NOT REALLY BRINGING
ANY PRECIPITATION WITH IT DUE TO LACK OF MOISTURE. HOWEVER...850MB
TEMPS FALL FURTHER...DOWN TO -11 TO -15C. BRIEF WARMING SHOULD OCCUR
TUESDAY NIGHT AS A WEAK UPPER RIDGE CROSSES IN THE WAKE OF TUESDAYS
SHORTWAVE TROUGH. THEN THIS GETS REPLACE BY A ZONAL FLOW FOR
WEDNESDAY INTO THURSDAY IN RESPONSE TO A SERIES OF SHORTWAVES
CROSSING SOUTHERN CANADA. THIS FLOW SETUP SHOULD ALLOW FOR DRY BUT
COOL CONDITIONS TO CONTINUE. ALL MODELS THEN INDICATE A DEEP
TROUGH DROPPING SOUTH THROUGH THE NORTHERN PLAINS THURSDAY NIGHT.
AHEAD OF THIS TROUGH...SOME PRECIP COULD OCCUR DUE TO DPVA AND
ISENTROPIC LIFT...THOUGH MOISTURE AGAIN IS QUESTIONABLE. INCLUDED
A 20 PERCENT CHANCE OF SNOW ACROSS THE SOUTHERN PORTIONS OF THE
FORECAST AREA...IN-LINE WITH THE 03.00Z GFS/ECMWF. THE UPPER
TROUGHING MOVES INTO THE AREA ON FRIDAY...BRINGING AIR MORE OF
ARCTIC ORIGIN ACROSS WITH 850MB TEMPS TANKING TO AROUND -20C. FOR
NOW FOLLOWED A CONSENSUS OF GUIDANCE FOR HIGHS AND LOWS THROUGHOUT
THE LONG TERM FORECAST...BUT MAY NEED TO LOWER HIGHS/LOWS FOR
FRIDAY AND FRIDAY NIGHT IF THIS -20C AT 850MB AIRMASS FORECAST
PERSISTS.
&&
.AVIATION...THROUGH 18Z SUNDAY
1135 AM CST SAT DEC 3 2011
PERIODS OF IFR CONDITIONS IN SNOW CAN BE EXPECTED AT TAF SITES
THROUGH LATE THIS EVENING. PLAN ON A RAIN/SNOW MIX EARLY THIS
AFTERNOON...SWITCHING OVER TO ALL SNOW BY MID AFTERNOON AT KRST
AND BY LATE AFTERNOON AT KLSE. VISIBILITIES WILL BE REDUCED TO
LESS THAN ONE MILE AT TIMES IN THE HEAVIER SNOWS. LOOK FOR
CEILINGS TO FALL INTO THE LIFR CATEGORY AT KRST DURING THE
HEAVIEST SNOW LATE THIS AFTERNOON INTO EARLY THIS EVENING...WITH
CEILINGS FALLING TO AROUND 200 FT. VLIFR CONDITIONS MAY DEVELOP IN
THE HEAVIEST SNOWS WITH VISIBILITIES POSSIBLY FALLING TO AROUND
ONE QUARTER OF A MILE A TIMES. THE SNOW WILL TAPER BY 09Z TONIGHT
AT KRST. PRECIPITATION IS EXPECTED TO SWITCH OVER FREEZING DRIZZLE
BY 08Z AT KLSE...WITH FREEZING DRIZZLE ENDING AROUND 11Z. LOOK
FOR CEILINGS TO GRADUALLY IMPROVE EARLY SUNDAY MORNING...WITH
CEILINGS IN THE 800 TO 1000 FT RANGE AROUND DAY BREAK. LOOK FOR
IFR/MVFR STRATUS TO PERSIST AT THE TAF SITES THROUGH THE LATE
MORNING HOURS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
139 PM CST SAT DEC 3 2011
WI...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 AM CST
SUNDAY FOR WIZ041>043-053.
WINTER WEATHER ADVISORY UNTIL 6 AM CST SUNDAY FOR WIZ017-029-
032>034.
MN...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 AM CST
SUNDAY FOR MNZ096.
WINTER WEATHER ADVISORY UNTIL 6 AM CST SUNDAY FOR MNZ079-086>088-
094-095.
IA...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 AM CST
SUNDAY FOR IAZ010-011-019.
WINTER WEATHER ADVISORY UNTIL 6 AM CST SUNDAY FOR IAZ008-009-018.
&&
$$
SHORT TERM...AJ
LONG TERM....AJ
AVIATION.....WETENKAMP