FXUS63 KDVN 022018
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
218 PM CST WED DEC 2 2009
.SYNOPSIS...
IMPRESSIVE -3 TO -4 SIGMA UPPER LOW IN THE MID-SOUTH ASSOCIATED WITH
160 METER HEIGHT FALLS AT 500 MB. STRONG LOW PRESSURE IN TN WITH
SURFACE ISSALLABARIC ANALYSIS INDICATING STRONG 3-HR PRESSURE FALLS
OF 8 MB CURRENTLY IN SOUTHERN OH SO MODELS TAKING CYCLONE FROM THE
MID-SOUTH TO NEW ENGLAND LOOKS GOOD. LARGE RAIN SHIELD SPREADING AS
FAR NORTH AS CENTRAL IL AT THIS TIME. HOWEVER 12Z DVN SOUNDING
INDICATED VERY DRY AIR BELOW 550 MB. IN THE MEANTIME...UPPER TROUGH
DIVING SOUTHWARD INTO THE CENTRAL UNITED STATES. MODIFIED ARCTIC AIR
DUMPING INTO THE PLAINS WHERE CURRENT TEMPS ARE ONLY IN THE 20S...
ALONG WITH GUSTY NW WINDS. ..HAASE..
&&
.SHORT TERM...TONIGHT AND THURSDAY...
SOUTHERN STORM SYSTEM PHASING WITH THE NORTHERN STREAM TROUGH
RESULTING IN A DEEPENING BUT RAPIDLY MOVING CYCLONE TO NEW ENGLAND
BY THURSDAY. REALLY NO SURPRISES AS OPERATIONAL MODELS KEEP THE BULK
OF THE PRECIPITATION EAST AND SOUTH OF THE DVN CWA...JUST BARELY
GRAZING OUR FAR EASTERN CWA. THEREFORE WILL CONTINUE WITH SMALL POPS
THIS EVENING IN THAT AREA. AFTER MIDNIGHT WILL KEEP MENTION OF
FLURRIES OVER MUCH OF THE CWA IN THE STRONG COLD AIR ADVECTION
PATTERN.
MODELS ALSO SIMILAR IN COLD POCKET ASSOCIATED WITH THE CENTRAL
UNITED STATES DEEP TROUGH MOVING INTO THE REGION ON THURSDAY.
FORECAST SOUNDINGS CONTINUE TO INDICATE STEEP LOW LEVEL LAPSE RATES
AND DEEP MIXING ON THURSDAY. 850 MB TEMPS OF -13C WITH 500 MB TEMPS
OF -35C. SCATTERED SNOW SHOWERS EXPECTED BUT ACCUMULATIONS MINOR IF
ANY.
TEMPERATURES...AS CYCLONE MOVES INTO OHIO THIS EVENING THE REALLY
COLD AIR WAITING IN THE WINGS TO OUR NORTHWEST WILL RAPIDLY GET
PULLED SOUTHEASTWARD INTO THE DVN CWA. MIN TEMPS TONIGHT SHOULD BE
IN THE 20S WITH MAX TEMPS ON THURSDAY STRUGGLING TO REACH THE
FREEZING MARK AT MOST LOCATIONS.
GOOD NEWS...THE ONLY SNOW COVER IN THE UPPER MIDWEST IS 2 TO 4
INCHES FROM PORTIONS OF ND TO EXTREME NORTHERN MN. LUCKILY THIS
AIRMASS WILL BE MODIFIED AS IT FLOWS ACROSS MOSTLY BARE GROUND.
OTHERWISE IT WOULD BE AT LEAST 10 DEGREES COLDER IF THERE WAS
EXTENSIVE SNOW COVER. THE BAD NEWS...THURSDAY SHOULD BE THE COLDEST
DAY SINCE MARCH 12 2009...A RUN OF NEARLY 9 MONTHS THAT WE ASSUME
WILL COME TO AN END. NICE WHILE IT LASTED.
..HAASE..
.LONG TERM...THURSDAY NIGHT THROUGH NEXT WEDNESDAY...
SHORTWAVE TROUGH TO LIFT NORTHEAST INTO ONTARIO PROVINCE BY 12Z FRI
WITH FUJIWHARA EFFECT ENSUING... AS CYCLONE CENTER ORBITS ABOUT
ANOTHER CYCLONE CENTER ROTATING DOWN FROM HUDSON BAY THROUGH THE
UPPER MIDWEST AND GREAT LAKES FIRST HALF OF THE WEEKEND. SOME
LINGERING FLURRIES POSSIBLE THURS NGT INTO FRI WITH POSSIBILITY OF
ISOLD -SHSN FRI NORTH HALF OR SO WITH COLD POOL... STEEP LAPSE RATES
AND CYCLONIC FLOW. OTHERWISE... CONTINUATION OF CLOUDS WITH SOME
BREAKS AND COLD TEMPS WITH READINGS BELOW NORMAL THROUGH FRI. MINS
FRI NGT ESPECIALLY CHALLENGING AS WEAK RIDGING PASSES THROUGH FIRST
HALF OF NGT FOLLOWED BY RETURN FLOW/WARM ADVECTION COMMENCING ON
BACKSIDE. THUS... LIKELY TO SEE TEMPS CRASH FRI EVE BEFORE HOLDING
STEADY AND/OR RISING A BIT OVRNGT WITH SLY WINDS DEVELOPING. LOCAL
MIN TEMP TECHNIQUE SUPPORTS WIDESPREAD TEENS TO NEAR 20 DEGS ON
LOWS... AND WOULD SUGGEST POTENTIAL TO BE AS COLD AS AROUND 10-12F
IN COLD DRAINAGE AREAS NORTH SHOULD RIDGING SLOW DOWN AND WINDS
SUBSIDE FOR ANY LENGTH. FOR NOW... HAVE GONE WITH BLEND FAVORING
TOWARD WARMER SIDE AS APPEARS MORE CLOUDS AND WINDS TO STAY UP
KEEPING BL MIXED. WARMING TREND CONTINUES SAT WITH TEMPS REBOUNDING
TO NEAR NORMAL. KEPT DRY ON SAT WITH MOISTURE LIMITED AND
SUGGESTIONS OF AREA IN BETWEEN ENERGY CENTERS... WITH MAIN BOUT OF
ENERGY PASSING TO OUR NORTH ACROSS THE UPPER MIDWEST AND THE GREAT
LAKES... WHILE MORE ROBUST TROUGH CONTINUES TO DIG THROUGH THE WEST.
NEXT PCPN CHC IN THE FORM OF SNOW STILL LOOKS TO ARRIVE LATE SUN PM/EVE
LINGERING INTO FIRST HALF OF MON... AS INITIAL PIECE OF ENERGY EJECTS
FROM WESTERN TROUGH AND RIPPLES ALONG BAROCLINIC ZONE. WITH MOISTURE
LIMITED PCPN LOOKS TO FOCUS ALONG AND ESPECIALLY BEHIND INVERTED SFC
TROUGH AS IT SLIDES EASTWARD FROM PLAINS THROUGH THE MID MISSISSIPPI
VALLEY. DESPITE LIMITED MOISTURE... DYNAMICS DECENT WITH AID OF
LEFT EXIT OF JET AND ALSO INTERACTION WITH TIGHT BAROCLINIC ZONE TO
PRODUCE BAND OF SNOW ACCUM OF A FEW INCHES... SOMETHING TO PIN DOWN IN
COMING DAYS.
MON-WED... MEDIUM RANGE SUPPORTS GENERALLY SPLIT/SEMI-ZONAL FLOW TO
PREVAIL DURING PD WITH TEMPS NEAR TO BELOW NORMAL. JET AND BAROCLINIC
ZONE WILL BE NEARBY AND THUS PORTIONS OF AREA WILL REMAIN IN LINE
FOR PCPN CHCS (SNOW)... WHICH ATTIM SEEM TO BE FOCUSED LATE TUE INTO
WED MAINLY ACROSS THE SOUTH. GFS THOUGH FURTHEST NORTH AND MORE
AGGRESSIVE ON PCPN AS IT SUGGESTS MORE PHASING OF STREAMS... WHEREAS
LATEST ECMWF UNPHASED AND WEAKER/FURTHER SOUTH. UKMET MORE OMINOUS
WITH RESPECT TO SLOWER/PHASED AND STRONGER SOLUTION... WHICH WOULD
SUPPORT POTENTIAL OF DECENT SYSTEM EJECTING NEAR TO SOUTH OF AREA MID
WEEK OR SO... WHICH IS PLAUSIBLE GIVEN EXTENT OF ENERGY... JET AND
STRENGTH OF BAROCLINIC ZONE. MAGNITUDE OF SYSTEM TO ALSO HAVE BIG
IMPACT ON TEMPS IMMEDIATELY BEYOND SCOPE OF CURRENT EXTENDED... AS
WEAKER LESS PHASED SOLUTIONS WOULD KEEP SEMI-ZONAL FLOW AND HOLD BRUNT
OF ARCTIC AIR NORTH... WHEREAS A MORE PHASED STRONGER SOLUTION WOULD
CERTAINLY ALLOW FOR CHUNK OF ARCTIC AIR TO SPILL SOUTHWARD. NEEDLESS
TO SAY LOTS OF UNCERTAINTY AND PLENTY TO WATCH FOR IN THE COMING DAYS.
..05..
&&
.AVIATION...
STRONG STORM SYSTEM TRACKING FROM THE MID-SOUTH TO OHIO TONIGHT.
MVFR CIGS ASSOCIATED WITH THIS SYSTEM WILL GRAZE KBRL/KMLI REMAINDER
OF THIS AFTERNOON. EXTENSIVE AREA OF MVFR CIGS FROM MN TO WESTERN IA
WILL RAPIDLY SPREAD SOUTHEAST INTO ALL TAF SITES IN EASTERN IA LATE
THIS AFTERNOON AND OVERNIGHT...CONTINUING ON THURSDAY. FLURRIES
EXPECTED AFTER MIDNIGHT WITH SCATTERED SNOW SHOWERS ON THURSDAY.
NORTHWEST WINDS 10-20 KNOTS WITH GUSTS TO 25 KNOTS THROUGH TONIGHT
...THEN 10-20 KNOTS ON THURSDAY.
..HAASE..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
HAASE/05
