NORTHEAST AND NORTH CENTRAL COLORADO AREA FORECAST DISCUSSION
NWS DENVER COLORADO
AFDDEN 215 PM MST THU JAN 24 2002
SHORT TERM DISCUSSION: CONCERN TONIGHT WILL BE FOR ANOTHER POTENTIAL
WIND EVENT FOR THE FOOTHILLS AND ADJACENT AREAS FOR LATE TNT AND
FRI. UPPER RIDGE ALOFT WILL FLATTEN AND SHIFT OVER THE ROCKY MTN RGN
AS FLOW BACKS AROUND TO WESTERLY BY FRI MORNING. STRONG WAA WILL
CONTINUE IN THE MID LVLS WITH GOOD MTN TOP INVERSION DEVELOPING TNT
AND CONTINUING ON FRI. SURFACE GRADIENT WILL ALSO CONTINUE TO
TIGHTEN AS MESOETA SHOWING ABOUT 15-17 MB DIFFERENCE AT THE SFC
BETWEEN DEN AND GJT DURING FRI AM. THIS LOOKS REASONABLE AS PRESS
FALLS ALREADY TAKING PLACE OVER THE NRN ROCKYS WITH LEE TROF
DEVELOPING OVER ERN CO. X-SECTIONS SHOWING 40-50KT SLIDING DOWN EAST
SLOPES ALONG WITH THE STRONG MTN LVL STABILITY JUST ABV 700MB. STEEP
LAPSE RATES ALOFT ALONG WITH A GOOD SHEAR PROFILE LOOKS LIKE A GOOD
SET UP FOR AN AMPLIFIED MTN WAVE. LOCAL WIND PROGRAMS ALSO SHOWING
HI POTENTIAL FOR STRONG WINDS IN AND NEAR THE FOOTHILLS WITH FCSTS
GUSTS NEAR 80 MPH.
LOOKING AT SOME REAL DATA...ACARS SOUNDINGS ACROSS OREGON THIS
MORNING ALREADY SHOWING THE WINDS BACKING AROUND WESTERLY WITH ABOUT
55KT AT 650 MB AND VERY LITTLE SPEED OR DIRECTIONAL SHEAR UP TO 350
MB. THIS CONICIDES WHAT MODELS ARE SHOWING. CAN'T REALLY FIND ANY
FACTORS WHICH WOULD GO AGAINST A HI WIND EVENT IN THE FOOTHILLS.
THEREFORE WITH CONFIENCE HIGH...WILL GO RIGHT TO A WARNING IN THE
FOOTHILLS FOR TNT/FRI OVER THE FOOTHILLS. THE STRONGEST WINDS WOULD
BE AFTER 06Z TNT...BUT WITH SURFACE GRADIENT ALREADY THIS STRONG
WILL RATHER JUST COVER THE WHOLE TNT PRD. NOT QUITE AS CONFIENT
ABOUT THE HI WNDS OVER THE ADJ FOOTHILLS AREAS OF ZNS 38..39. A
LITTLE CONCERNED ABOUT THE SNOW COVER WITH CURRENT COLD AIR IN PLACE
WHICH WOULD KEEP WINDS ABV SURFACE. BUT FEEL AS FRI PROGRESSES THE
WINDS SHOULD BE ABLE TO MIX TO THE SURFACE. WITH SOME UNCERTAINTY
WITH THESE AREAS WILL GO WITH A HI WIND WATCH AT THIS TIME FOR ZNS
38 AND 39 AS THE ESP TIGHT GRADIENT IN PLACE. THE EVENING AND MID
SHIFTS SHOULD GET A PRETTY GOOD IDEA BEFORE THE WINDS BUST THRU FRI
MORNING IN THESE AREAS. NO HILITES FOR THE HI MOUNTAINS EVEN THOUGH
IT WILL BE WINDY THERE AS WELL...BUT WITH NO EXTREME HIGHER WINDS
EXPECTED THEN THEY ARE USED TO.
MUCH WARMER IN THE TEMP FIELDS FOR LATER TNT AND FRI WITH INCREASING
WNDS AND SOME WAVE CLOUDS MAY START TEMPS RISING LATE IN THE NIGHT.
HIGHS ON FRI WILL BE APPROACHING 60...BUT WITH WAVE CLOUDS AND
CURRENT SNOW COVER...WILL BE A LITTLE ON THE PESIMISTIC SIDE.
ENTREKIN
LONG TERM DISCUSSION: AXIS OF FLAT UPR RIDGE MOVES JUST EAST OF
COLORADO BY SATURDAY MORNING WITH WINDS ALOFT GOING SWLY. BELOW 500
MBS AIR REMAINS QUITE DRY THRU SATURDAY NIGHT WITH SFC DEWPTS BELOW
15 DEG F ON THE PLAINS. MTN RIDGETOPS AND EAST FACING SLOPES WILL
CONTINUE WINDY SATURDAY AND SATURDAY NIGHT WITH 30-40KT CROSS
BARRIER WINDS. DO NOT SEE STRONG WINDS MIXING DOWN TO LOWER
ELEVATIONS EAST OF MTNS...EXCEPT MAYBE RIGHT UP AGAINST FOOTHILLS
IN BOULDER AND NRN JEFFERSON CTYS WHERE WLY GUSTS TO 30 MPH A
POSSIBILITY. OF NOTEWORTHLY WILL BE THE UNSEASONABLY WARM TEMPS
PROGD FOR SATURDAY. MODELS SHOW 700 MB TEMPS OF 1C TO 2C BY
SATURDAY AFTERNOON...EQUATING TO LOW/MID 60S IN THE FRONT RANGE
URBAN CORRIDOR AND UPR 50S/LWR 60S OUT ON THE PLAINS. BITTER COLD
AIR TRAPPED IN MTN VLYS BY STG MTN TOP INVERSION PAST COUPLE OF DAYS
SHOULD MODIFY QUITE A BIT WITH INVERSION DISAPPEARING. HOWEVER...
MAY NOT SEE TEMPS ON THE PLAINS REACHING MAX POTENTIAL SHOULD HIGH
LVL MOISTURE ROUNDING BOTTOM OF WEST COAST TROUGH PRODUCE WAVE
CLOUDS OVR THE FRONT RANGE SATURDAY AFTERNOON. CROSS SECTIONS SHOW
A WEAK MTN WAVE FORMING ABV 500 MBS AFT 18Z/SAT. SUNDAY CONTINUES
DRY WITH SWLY FLOW ALOFT...ALTHOUGH TEMPS NOT AS WARM WITH DOWNSLOPE
FLOW WEAKENING ALLOWING BNDRY LYR WINDS TO GO S-SELY DURING THE DAY.
ALSO SEE MORE MID AND HIGH LVL MOISTURE/CLOUDS PASSING OVER AREA ON
SUNDAY. STRENGTHENING SWLY FLOW ALOFT SHOULD PRODUCE ANOTHER WINDY
DAY FOR RIDGETOPS AND EAST FACING MTN SLOPES.
LOOKING AHEAD TO NEXT WEEK...MEDIUM RANGE MODELS CONTINUE TO SHOW A
DRAMATIC REVERSAL IN THE CURRENT WEATHER PATTERN. HIGH AMPLITUDE UPR
LVL TROF MOVG OVR THE GREAT BASIN MONDAY IS FCST TO BECOME ANCHORED
OVR THE RCKY MTNS AND GREAT PLAINS BY MID-WEEK. ECMWF...MRF...
CANADIAN GEM AND NOGAPS CONTINUE TO DIFFER ON THE TIMING AND
STRENGTH OF THE TROUGH AND THE SURGES OF ARCTIC AIR DROPPING SOUTH
OUT OF CENTRAL CANADA. OVERALL MODELS SHOW A WEAK PUSH OF ARCTIC
AIR INTO NERN CO MONDAY...ONLY TO RETREAT WITH SMALL WARMUP ON TUE.
A SECOND STRONGER AND MUCH COLDER SURGE IS PROGD TO ARRIVE TUESDAY
NIGHT POSSIBLY PRODUCING LIGHT UPSLOPE SNOWFALL EAST OF MTNS. AS UPR
TROUGH SHIFTS EAST MRF SHOWS STG NWLY FLOW BRINGING DOWN ANOTHER
BATCH OF BITTER COLD AIR LATE WED INTO THU. BASED ON 850 MB TEMPS
OFF MRF THURSDAY TEMPS ON THE PLAINS SHOULD NOT GET OUT OF THE
SINGLE DIGITS ABOVE ZERO. CLIMATOLOGICALLY SPEAKING...SUCH TEMPS
NOT UNREASONABLE FOR THIS TIME OF YEAR. WILL TREND TEMPS DOWNWARD
THRU MID-WEEK...ALTHOUGH NOT SURE MODELS HAVE A HANDLE ON THE REALLY
COLD BOUNDARY LAYER AIR AND THE ENSEMBLES CONTINUE TO OFFER A WIDE
RANGE OF SOLUTIONS. BAKER
.DEN...HI WIND WARNING...ZNS 35..36. FOR TNT AND FRI.
...HI WIND WATCH.....ZNS 38..39. FOR LATE TNT AND FRI.
AREA FORECAST DISCUSSION
NWS CHICAGO IL
AFDCHI 900 PM CST THU JAN 24 2002
THE SURFACE ANALYSIS AT 0200 UTC SHOWS WARM TO NEUTRAL TEMPERATURE
ADVECTION INTO THE FORECAST AREA OF NORTHEAST ILLINOIS AND NORTHWEST
INDIANA. THE DEWPOINTS SHOW DRIER AIR ADVECTING INTO THE FORECAST
AREA. LOW LEVEL WINDS 500 M AGL AND 925 MB SHOW WEST USING PROFILER
DATA AT 0200 UTC. STILL NORTHWEST WINDS AT 850 MB. ACARS SOUNDING AT
ORD AT 0203 UTC SHOW WEAK INVERSION AND WEST LOW LEVEL WINDS. WILL
ADJUST WIND FORECAST FOR NORTHWEST INDIANA AND ADJUST TEMPERATURES
BASED ON MOISTURE AND TEMPERATURE ADVECTION.
.CHI...NONE
WHW
SOUTHEAST MICHIGAN AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
AFDDTX 305 PM EST THU JAN 24 2002
FORECAST PROBLEM FOR THE NEXT 24 HOURS APPEARS TO BE CLOUD COVER.
BOTH ETA AND NGM SHOWING MOISTURE DECREASING IN THE LOWER LAYERS
TONIGHT SO THAT THE SOUTHERN COUNTIES SHOULD BE PARTLY CLOUDY BY
00Z... WITH THE NORTHERN COUNTIES BECOMING PARTLY CLOUDY OVERNIGHT.
AVN NOT AS OPTIMISTIC AND KEEPS THE LOWER LEVEL MOISTURE IN THROUGH
FRIDAY. PRESENT TREND ON THE SATELLITE WOULD POINT TO KEEPING THE
CLOUDS IN ACROSS ALL OF SOUTHEAST MICHIGAN THIS EVENING AND THEN GO
WITH DECREASING CLOUDINESS. COOL... SHALLOW... AIRMASS WILL BE OVER
SOUTHEAST MICHIGAN TONIGHT WITH A PRETTY GOOD INVERSION IN PLACE.
ACARS DATA SHOWS THE INVERSION TO BE A LITTLE STRONGER THAN
INDICATED BY MODEL SOUNDINGS AND THIS WOULD ALSO POINT TO KEEPING
MOSTLY CLOUDY FOR THE THE EVENING HOURS. ALSO HAVE TO WORRY ABOUT
SOME FREEZING DRIZZLE OR FLURRIES THIS EVENING WITH THE LOWER LAYERS
KEEPING NEAR SATURATION.
WARM ADVECTION MID LEVEL CLOUDINESS WILL SPREAD INTO THE NORTH HALF
OF THE FORECAST AREA FRIDAY AND THEN MOVE OFF TO THE EAST FRIDAY
EVENING. PARTLY SUNNY IN THE NORTH AND MOSTLY SUNNY IN THE SOUTH
SHOULD COVER THIS.
RATHER BENIGN WEATHER FOR SATURDAY AND SUNDAY WITH LOTS OF SUNSHINE
EXPECTED. TEMPERATURES WILL CONTINUE THEIR WARMING TREND AND STAY
ABOVE NORMAL.
EXTENDED...
OVERALL MODELS NOT TOO DIFFERENT THROUGH THE MID PORTION OF NEXT
WEEK AS UPPER AIR PATTERN SHIFTS FROM NEARLY ZONAL FLOW TO A MORE
AMPLIFIED PATTERN. BY THE FIRST PART OF NEXT WEEK AN UPPER LEVEL
RIDGE DEVELOPS ALONG THE WEST COAST AND A BROAD LONG WAVE TROF MOVES
INTO THE PLAINS STATES. THE TROF EXTENDS ITSELF TO THE LAKES REGION
BY MID WEEK WITH A STORM SYSTEM MOVING THROUGH THE REGION ON
TUESDAY. BOTH MRF AND CANADIAN MODELS TAKE THE LOW WEST OF
MICHIGAN... WHILE THE ETA-XX BRINGS A LOW ACROSS SOUTHEAST MICHIGAN
LATE TUESDAY. THE ETA-XX TRACK WOULD ALLOW THE COLD AIR TO GET INTO
SOUTHEAST MICHIGAN MUCH FASTER THAN THE OTHER 2 MODELS AND WOULD
POINT TO SNOW IN PORTION OF SOUTHEAST MICHIGAN TUESDAY AFTERNOON.
AT THIS POINT WILL HAVE THE FORECAST LEANING TOWARDS THE MRF AND
CANADIAN SOLUTIONS AND KEEP ALL THE PRECIPITATION IN SOUTHEAST
MICHIGAN ON TUESDAY LIQUID.
THERE IS QUITE A BIT OF COLD AIR BEHIND THIS SYSTEM AS THE UPPER
RIDGE WILL ALLOW A STRONG HIGH TO BUILD SOUTHWARD OUT CANADA.
QUESTION BECOMES HOW FAR SOUTH THE COLD AIR WILL BE ABLE TO
PENETRATE INTO THE LAKES REGION. MODELS TYPICALLY DO NOT HANDLE
THESE SHALLOW... COLD... AIRMASSES THAT WELL... AND THE COLD AIR
GOES FURTHER SOUTH THAN INDICATED. HOWEVER... THERE IS NOT A LOT OF
SNOW COVER IN THE NATION AND THIS SHOULD RETARD THE SOUTHWARD
MOVEMENT SOMEWHAT. AT THIS POINT WILL HAVE TEMPERATURES RETURNING TO
NEAR NORMAL VALUES FOR WEDNESDAY AND THURSDAY. MRF IS SHOWING
ANOTHER LOW MOVING OUT OF THE PLAINS FOR THE LATE WEDNESDAY INTO
THURSDAY TIME FRAME. SURPRISINGLY IT MOVES THE LOW WEST OF THE
FORECAST AREA AGAIN. GIVEN THAT WE ARE TALKING ABOUT DAY 7 HERE WILL
ONLY MENTION A CHANCE OF SNOW FOR THURSDAY.
THE TEMPERATURE FORECAST PRESENTS A PROBLEM. CURRENT INDICATIONS ARE
THAT READINGS WILL RISE TO AROUND 50 FOR BOTH SUNDAY AND MONDAY.
RECORD HIGH FOR DETROIT ON SUNDAY IS 61 SET IN 1916 WHILE THE RECORD
HIGH FOR FLINT IS 52 SET IN 1944. THE 52 IS REACHABLE AT FLINT...
WHILE THE 61 AT DTW SHOULD BE SAFE. ON MONDAY THE RECORD AT DETROIT
IS 51 SET IN 1914 AND FOR FLINT IT IS ALSO 51 SET IN 1989. BOTH OF
THESE VALUES COULD BE REACHED ON MONDAY. HATE FORECASTING RECORD
HIGHS 4 DAYS IN ADVANCE... BUT THAT IS WHAT WILL BE IN THE FORECAST.
.DTX...NONE.
KEYES